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| United States Patent |
6,005,668
|
|
Held, III
, et al.
|
December 21, 1999
|
Detecting defects in plastic and similar surfaces
Abstract
A "highlighter" liquid for detecting cosmetic defects in non-metallic
surfaces, particularly those intended for high quality automotive finishes
comprises organic substances each molecule of which contains at least one
continuosly chemically bonded chain or ring of atoms in which there are at
least two carbon atoms and at least two oxygen, nitrogen, sulfur, and
phosphorus heteroatoms, the carbon atoms and heteroatoms being arranged in
such an order along the chain or ring that (i) each heteroatom is bonded
to at least one carbon atom and (ii) the chain does not include more than
three consecutive continuosly chemically bonded carbon atoms. Particularly
suitable materials include glycerin, propylene glycol, low molecular
weight glycol condensation polymers, and monoethers of these glycol
condensation polymers. Water is also usually present in the highlighter
liquid, which has a long open time and does not damage the substrate even
if left in place for a day or more.
| Inventors:
|
Held, III; Theodore D. (Grosse Pointe Farms, MI);
Cormier; Gerald J. (Oxford, MI)
|
| Assignee:
|
Henkel Corporation (Gulph Mills, PA)
|
| Appl. No.:
|
112389 |
| Filed:
|
July 9, 1998 |
| Current U.S. Class: |
356/600; 356/613; 436/5 |
| Intern'l Class: |
G01N 021/55 |
| Field of Search: |
356/371,376,239.8,237.3
436/5
|
References Cited [Referenced By]
U.S. Patent Documents
| 4514045 | Apr., 1985 | Huffman et al. | 356/351.
|
| 4629319 | Dec., 1986 | Clarke et al. | 356/237.
|
| 5745238 | Apr., 1998 | Long et al. | 356/376.
|
Primary Examiner: Font; Frank G.
Assistant Examiner: Nguyen; Tu
Attorney, Agent or Firm: Szoke; Ernest G., Jaeschke; Wayne C., Wisdom, Jr.; Norvell E.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
Priority for this application is claimed under 35 U.S.C. .sctn. 119(e) from
U.S. Provisional Application Ser. No. 60/052,471 filed Jul. 14, 1997, and
60/057,528, filed Sep. 4, 1997.
Claims
The invention claimed is:
1. A process for determining whether a non-metallic surface having a matte
finish includes any geometrical irregularities that are not readily
visually detectable while the surface remains unreflective, said process
comprising steps of:
(I) covering all parts of the non-metallic surface on which a determination
of presence or absence of said geometrical irregularities is to be made
with a glossy and specularly reflective liquid film that comprises:
(A) a concentration of a dissolved component consisting of one or more
organic substances each molecule of which contains at least one
continuously chemically bonded chain or ring of atoms in which there are
at least two carbon atoms and at least two heteroatoms selected from the
group consisting of oxygen, nitrogen, sulfur, and phosphorus atoms, said
carbon atoms and said heteroatoms being arranged in such an order along
said continuously chemically bonded chain or ring that (i) each heteroatom
is bonded to at least one carbon atom and (ii) the chain does not include
more than three consecutive continuously chemically bonded carbon atoms;
and
(II) visually examining reflectivity of light from all parts of the glossy
and specularly reflective liquid film formed over the non-metallic surface
in step (I), and determining whether the reflectivity of light is visually
uniform over all parts of the glossy and specularly reflective liquid
film.
2. A process according to claim 1, wherein said glossy and specularly
reflective film, when it is first applied as a covering over the
non-metallic surface, comprises water and at least about 5.0% of component
(A) as defined in claim 1 and has a pH value within the range from about
5.5 to about 11.0.
3. A process according to claim 2, wherein said glossy and specularly
reflective film, when it is first applied as a covering over the
non-metallic surface, has a pH value within the range from about 6.3 to
about 10.2 and comprises at least about 0.50% of surfactants belonging to
component (A) and at least about 4.5% of molecules selected from the group
consisting of (i) homopolymers of ethylene glycol; (ii) monoethers of
homopolymers of ethylene glycol, monoethers of homopolymers of propylene
glycol, and monoethers of copolymers of ethylene and propylene glycols;
and (iii) glycerin and propylene glycol.
4. A process according to claim 3, wherein said glossy and specularly
reflective film, when it is first applied as a covering over the
non-metallic surface, has a pH value within the range from about 7.6 to
about 9.9 and comprises at least about 0.70% of surfactant molecules each
of which contains an alkyl imidazoline moiety and at least about 6.0% of a
total of glycerin and propylene glycol.
5. A process according to claim 4, wherein said glossy and specularly
reflective film, when it is first applied as a covering over the
non-metallic surface, has a pH value within the range from about 8.5 to
about 9.9 and comprises: (i) from about 1.0 to about 6% of surfactant
molecules each of which contains an alkyl imidazoline moiety that
comprises, chemically bonded to a nitrogen atom in the imidazoline moiety,
at least one substituent moiety selected from the group consisting of
hydroxyalkyl moieties, carboxyalkyl moieties, and carbonate moieties; (ii)
from about 12.0 to about 31% of a total of glycerin and propylene glycol;
(iii) at least 0.012% of surfactant selected from the group consisting of
fluorinated esters of phosphoric and phosphinic acids; (iv) from about
0.035 to about 0.060% of acrylic acid thickening agent; (v) a
preservative-effective amount of a preservative component selected from
the group consisting of molecules each of which includes at least one
isothiazolin-3-one moiety; and not more than about 1.0% of a total of
glycol polymers and glycol polymer ethers.
6. A process according to claim 5, wherein said non-metallic surface is a
surface of thermoplastic polyolefin.
7. A process according to claim 1, wherein said non-metallic surface is a
surface of thermoplastic polyolefin.
8. A process according to claim 3, wherein said glossy and specularly
reflective film, when it is first applied as a covering over the
non-metallic surface, has a pH value within the range from about 7.6 to
about 9.9 and comprises: (i) at least about 0.70% of surfactant molecules
each of which contains an alkyl imidazoline moiety; (ii) at least about
12% of molecules selected from the group consisting of (ii.1) homopolymers
of ethylene glycol and (ii.2) monoethers of polymers of (ii.2.1) ethylene
glycol, (ii.2.2) propylene glycol, and (ii.2.3) both ethylene and
propylene glycols; and (iii) not more than 6.0% of a total of glycerin and
propylene glycol.
9. A process according to claim 8, wherein said glossy and specularly
reflective film, when it is first applied as a covering over the
non-metallic surface, has a pH value within the range from about 8.8 to
about 9.3 and comprises: (i) from about 1.0 to about 6% of surfactant
molecules each of which contains an alkyl imidazoline moiety that
comprises, chemically bonded to a nitrogen atom in the imidazoline moiety,
at least one substituent moiety selected from the group consisting of
hydroxyalkyl moieties, carboxyalkyl moieties, and carbonate moieties; (ii)
from about 17 to about 25% of a total of molecules selected from the group
consisting of (ii.1) homopolymers of ethylene glycol and (ii.2) monoethers
of polymers of (ii.2.1) ethylene glycol, (ii.2.2) propylene glycol, and
(ii.2.3) both ethylene and propylene glycols; (iii) at least 0.012% of
surfactant selected from the group consisting of fluorinated esters of
phosphoric and phosphinic acids; (iv) from about 0.035 to about 0.060% of
acrylic acid thickening agent; (v) a preservative-effective amount of a
preservative component selected from the group consisting of molecules
each of which includes at least one isothiazolin-3-one moiety; and (vi)
not more than 1.0% of a total of glycerin and propylene glycol.
10. A process according to claim 9, wherein said non-metallic surface is a
surface of thermoplastic polyolefin.
11. A process according to claim 9, wherein said glossy and specularly
reflective film, when it is first applied as a covering over the
non-metallic surface, has a pH value within the range from about 7.6 to
about 9.9 and has been made by mixing into the liquid constituting said
glossy and specularly reflective film: (i) at least about 0.70% of
surfactant molecules each of which contains an alkyl imidazoline moiety;
(ii) at least about 12% of molecules selected from the group consisting of
(ii.1) homopolymers of ethylene glycol and (ii.2) monoethers of polymers
of (ii.2.1) ethylene glycol, (ii.2.2) propylene glycol, and (ii.2.3) both
ethylene and propylene glycols; and (iii) not more than 6.0% of a total of
glycerin and propylene glycol.
12. A process according to claim 11, wherein said glossy and specularly
reflective film has a pH value within the range from about 8.8 to about
9.3 and has been made by mixing into the liquid constituting said glossy
and specularly reflective film: (i) from about 1.0 to about 6% of
surfactant molecules each of which contains an alkyl imidazoline moiety
that comprises, chemically bonded to a nitrogen atom in the imidazoline
moiety, at least one substituent moiety selected from the group consisting
of hydroxyalkyl moieties, carboxyalkyl moieties, and carbonate moieties;
(ii) from about 17 to about 25% of a total of molecules selected from the
group consisting of (ii.1) homopolymers of ethylene glycol and (ii.2)
monoethers of polymers of (ii.2.1) ethylene glycol, (ii.2.2) propylene
glycol, and (ii.2.3) both ethylene and propylene glycols; (iii) at least
0.012% of surfactant selected from the group consisting of fluorinated
esters of phosphoric and phosphinic acids; (iv) from about 0.035 to about
0.060% of acrylic acid thickening agent; (v) a preservative-effective
amount of a preservative component selected from the group consisting of
molecules each of which includes at least one isothiazolin-3-one moiety;
and, (vi) not more than 1.0% of a total of glycerin and propylene glycol.
13. A process according to claim 12, wherein said non-metallic surface is a
surface of thermoplastic polyolefin.
14. A process for determining whether a non-metallic surface having a matte
finish includes any geometrical irregularities that are not readily
visually detectable while the surface remains unreflective, said process
comprising steps of:
(I) covering all parts of the non-metallic surface on which a determination
of presence or absence of said geometrical irregularities is to be made
with a glossy and specularly reflective liquid film that has been made by
mixing with one another:
(A) a concentration of a water soluble component consisting of one or more
organic substances each molecule of which contains at least one
continuously chemically bonded chain or ring of atoms in which there are
at least two carbon atoms and at least two heteroatoms selected from the
group consisting of oxygen, nitrogen, sulfur, and phosphorus atoms, said
carbon atoms and said heteroatoms being arranged in such an order along
said continuously chemically bonded chain or ring that (i) each heteroatom
is bonded to at least one carbon atom and (ii) the chain does not include
more than three consecutive continuously chemically bonded carbon atoms;
and
(B) water; and
(II) visually examining reflectivity of light from all parts of the glossy
and specularly reflective liquid film formed over the non-metallic surface
in step (I), and determining whether the reflectivity of light is visually
uniform over all parts of the glossy and specularly reflective liquid
film.
15. A process according to claim 14, wherein said glossy and specularly
reflective film, when it is first applied as a covering over the
non-metallic surface, has a pH value within the range from about 5.5 to
about 11.0 and has been made by mixing water and an amount of component
(A) as defined in claim 1 that constitutes at least about 5.0% of the
total glossy and specularly reflective film.
16. A process according to claim 15, wherein said glossy and specularly
reflective film, when it is first applied as a covering over the
non-metallic surface, has a pH value within the range from about 6.3 to
about 10.2 and has been made by mixing into the liquid constituting said
glossy and specularly reflective film at least about 0.50% of surfactants
belonging to component (A) and at least about 4.5% of molecules selected
from the group consisting of (i) homopolymers of ethylene glycol; (ii)
monoethers of homopolymers of ethylene glycol, monoethers of homopolymers
of propylene glycol, and monoethers of copolymers of ethylene and
propylene glycols; and (iii) glycerin and propylene glycol.
17. A process according to claim 16, wherein said glossy and specularly
reflective film, when it is first applied as a covering over the
non-metallic surface, has a pH value within the range from about 7.6 to
about 9.9 and has been made by mixing into the liquid constituting said
glossy and specularly reflective film at least about 0.70% of surfactant
molecules each of which contains an alkyl imidazoline moiety and at least
about 6.0% of a total of glycerin and propylene glycol.
18. A process according to claim 17, wherein said glossy and specularly
reflective film, when it is first applied as a covering over the
non-metallic surface, has a pH value within the range from about 8.5 to
about 9.9 and has been made by mixing into the liquid constituting said
glossy and specularly reflective film: (i) from about 1.0 to about 6% of
surfactant molecules each of which contains an alkyl imidazoline moiety
that comprises, chemically bonded to a nitrogen atom in the imidazoline
moiety, at least one substituent moiety selected from the group consisting
of hydroxyalkyl moieties, carboxyalkyl moieties, and carbonate moieties;
(ii) from about 12.0 to about 31% of a total of glycerin and propylene
glycol; (iii) at least 0.012% of surfactant selected from the group
consisting of fluorinated esters of phosphoric and phosphinic acids; (iv)
from about 0.035 to about 0.060% of acrylic acid thickening agent; (v) a
preservative-effective amount of a preservative component selected from
the group consisting of molecules each of which includes at least one
isothiazolin-3-one moiety; and not more than about 1.0% of a total of
glycol polymers and glycol polymer ethers.
19. A process according to claim 18, wherein said non-metallic surface is a
surface of thermoplastic polyolefin.
20. A process according to claim 14, wherein said non-metallic surface is a
surface of thermoplastic polyolefin.
Description
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
BACKGROUND OF THE INVENTION
This invention relates to compositions and processes for detecting
geometric irregularities in shaped non-metallic surfaces over at least
part of which pure liquid water will not spontaneously spread. The
invention more particularly relates to detecting such irregularities in
surfaces of articles of manufacture made of plastics, including
thermoplastics, more particularly articles constituted predominantly of
"engineering" plastics used as parts of automobile bodies. (For
convenience and brevity, the remainder of the description below will
generally refer only to plastic surfaces. However, it should be understood
that the invention may be applied, mutatis mutandis, to any other
non-metallic surface over which pure water does not spontaneously spread.
One common example of such a surface would be a conventionally primer
coated metal surface, when the primer is not glossy, but a final surface
finish over the primer will make the finished surface glossy. A surface
formed by any other non-glossy and non-metallic intermediate coating,
e.g., a primed surface of plastic sheet molding compound that is intended
to have a final glossy surface, can also advantageously be treated
according to the present invention.) Such articles are usually shaped by
molding and usually emerge from molding with a surface smooth to the touch
but often not smooth enough to be reflective or glossy. This type of
surface finish with low specular gloss will usually be described
hereinafter as "matte". Visual examination of a matte surfaced molded
plastic part only rarely reveals any visually perceptible non-uniformities
in the surface. Particularly difficult to detect are shallow but larger
scale non-uniformities often described as "waviness" or some similar term.
If such a molded plastic surface is intended for use on the exterior of an
automobile body, the surface is often coated with the same materials and
processes as are used for the exterior finish for metallic parts of
automobile bodies. After such coating has been completed, it has been
fairly often observed that the coated plastic surface appears blemished by
visually perceptible non-uniformity in one or more of gloss, color, or
surface texture in some parts of, usually in small spots or streaks on,
the coated surface, and that these defects can be determined to be due to
corresponding irregularities in the underlying surface rather than to
flaws in the coating itself. Such surface blemishes, often called in the
art and referred to later herein as "cosmetic" blemishes, defects, flaws,
or a like term, are generally unacceptable to buyers of new automobiles.
The cost of exterior automotive finishes, which often require at least
three separate coating compositions and processes to complete, is quite
high, and finished parts found to have a defective surface usually must be
scrapped. If the defects can be discovered before finishing begins, at
least the cost of the finishing of a defective part will be avoided, and
sometimes the defective part can economically be reworked to a
satisfactory surface quality and eventually used. As a result, methods,
simpler and less costly than completion of the normal finishing process,
of detecting surface defects on plastic articles of manufacture are highly
desirable.
Accordingly, one object of this invention is to provide a process, and any
composition(s) needed therein, for making readily visually detectable any
surface irregularities in plastic surfaces, particularly those having a
matte finish, that are not readily detectable while the surface remains
unreflective but will become readily visually apparent when these plastic
surfaces are given a coating with a conventional autobody exterior finish.
In order to be practically useful, any such process according to the
invention must be less costly than a process of forming a conventional
exterior autobody finish on the plastic surface. Preferably, a process
according to the invention also achieves at least one, and most preferably
all, of the following objectives: Any material, other than a component of
the desired final coating for the article as it is to be used by an
ultimate consumer, that is coated onto the surface to be tested is easily
removable from the surface, most preferably by a simple water rinse; no
deterioration in physical strength of the article having the plastic
surface being tested for irregularity results from the detection process;
no reduction in adhesion of any desired final coating occurs as a result
of the detection process; little or no corrosion of equipment used in the
process occurs; and the period of time during which the detection may be
completed, hereinafter usually denoted as the "open time", is at least,
with increasing preference in the order given, 1.0, 2.0, 3.0, 4.0, 5.0,
7.0, 10, or 15 minutes (hereinafter usually abbreviated as "min"); or 1,
3, 6, 12, 24, 48 or 72 hours. The conditions most favoring visual
perceptibility of cosmetic blemishes generally require the surface being
evaluated to be vertical or nearly vertical, so that these preferred
minimal limits on open time are to be understood as measured on a vertical
surface; any other angle of orientation of the surface should normally
result in a longer open time. Other concurrent and/or alternative objects
will be apparent from the description below.
Except in the claims and the operating examples, or where otherwise
expressly indicated, all numerical quantities in this description
indicating amounts of material or conditions of reaction and/or use are to
be understood as modified by the word "about" in describing the broadest
scope of the invention. Practice within the numerical limits stated is
generally preferred, however. Also, throughout the description, unless
expressly stated to the contrary: percent, "parts of", and ratio values
are by weight or mass; the term "polymer" includes "oligomer",
"copolymer", "terpolymer" and the like; the description of a group or
class of materials as suitable or preferred for a given purpose in
connection with the invention implies that mixtures of any two or more of
the members of the group or class are equally suitable or preferred;
description of constituents in chemical terms refers to the constituents
at the time of addition to any combination specified in the description or
of generation in situ within the composition by chemical reaction(s) noted
in the specification between one or more newly added constituents and one
or more constituents already present in the composition when the other
constituents are added, and does not necessarily preclude unspecified
chemical interactions among the constituents of a mixture once mixed;
specification of constituents in ionic form additionally implies the
presence of sufficient counterions to produce electrical neutrality for
the composition as a whole and for any substance added to the composition;
any counterions thus implicitly specified preferably are selected from
among other constituents explicitly specified in ionic form, to the extent
possible; otherwise such counterions may be freely selected, except for
avoiding counterons that act adversely to an object of the invention; the
word "mole" means "gram mole", and the word itself and all of its
grammatical variations may by used for any chemical species defined by all
of the types and numbers of atoms present in it, irrespective of whether
the species is ionic, neutral, unstable, hypothetical, or in fact a stable
neutral substance with well defined molecules; and the terms "solution",
"soluble", "homogeneous", and the like are to be understood as including
not only true equilibrium solutions or homogeneity but also dispersions
that show no visually detectable tendency toward phase separation over a
period of observation of at least 100, or preferably at least 1000, hours
during which the material is mechanically undisturbed and the temperature
of the material is maintained within the range of 18-25.degree. C.
BRIEF SUMMARY OF THE INVENTION
It has been found that at least the minimum object, and in preferred
embodiments two or more objects, of the invention as stated above can be
achieved by applying over a surface to be tested for susceptibility to
cosmetic blemishing a suitably selected liquid composition that forms a
glossy and specularly reflective liquid film over all of the surface to be
tested, this film persisting in place over the surface for a sufficient
time to enable an inspector to examine the exterior surface of the liquid
film, under the same lighting conditions as are used to examine
conventionally finished metal substrate exterior body parts for
automobiles, for any inconsistencies in reflectivity that highlight
surface irregularities in the solid surface most nearly underlying the
part of the liquid coating exhibiting a reflectivity that is inconsistent
with that of the bulk of the liquid coating. If no such inconsistencies
are observed, the plastic surface so tested can be reliably expected to
have a cosmetically flawless surface when properly finished with a
conventional autobody exterior finish system.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
Not applicable.
DETAILED DESCRIPTION OF THE INVENTION
An important part of preferred embodiments of this invention is the
selection of a suitable liquid composition for forming and constituting
the glossy and specularly reflective liquid film required by the
invention. For economy and avoidance of flammability hazards, a
water-based liquid is preferred. However, when many water-based liquids
are applied as a coating on the plastic materials of greatest current
commercial interest, a phenomenon, which has been named
"Swiss-cheese-dewetting", has been observed: An initially formed film of
these liquids is glossy and specularly reflective as required, but for
liquids susceptible to Swiss-cheese-dewetting, as the water in the liquid
film drains and evaporates, small "holes" in the film, the term "holes"
being understood to include areas of visually obvious non-uniform thinning
of the initially applied composition as well as complete disappearance or
drying of this initially applied composition, rapidly develop
spontaneously as water is lost from the initially applied composition. At
this point the liquid surface coating looks geometrically like a thin
slice of Swiss cheese, because it has apparently randomly placed mutually
distinct holes of various sizes within a continuous connected sheet. These
initially formed holes grow in size as the liquid around their perimeters
moves predominantly away from rather than toward the initial perforation
site. In severe cases, this phenomenon eventually results in the
collection of all the remaining liquid from the initially applied
composition into discrete drops on the surface. The development of one or
more holes that individually or collectively impair the overall specular
reflectivity of the liquid coating surface to an extent that is readily
perceptible visually by an inspector marks the end of the open time for a
film, because even one defect will cause the surface to be rated as
unacceptable.
Preferred compositions for use according to the invention comprise,
preferably consist essentially of, or more preferably consist of:
(A) a concentration of a dissolved component selected from a group
consisting of organic substances each molecule of which contains at least
one continuously chemically bonded chain or ring of atoms in which there
are at least two, or preferably at least three, carbon atoms and at least
two atoms selected from a group of heteroatoms, said group of heteroatoms
consisting of oxygen, nitrogen, sulfur, and phosphorus, preferably oxygen
and nitrogen, said carbon atoms and heteroatoms being arranged in such an
order along said continuously chemically bonded chain or ring that (i)
each heteroatom is bonded to at least one carbon atom and (ii) the chain
does not include more than three consecutive continuously chemically
bonded carbon atoms; this condition does not exclude bonding of either a
carbon atom or a heteroatom within said continuously chemically bonded
chain or ring to other carbon atoms not part of said continuously
chemically bonded chain or ring, and the bonding required within said
chain or ring may include double or triple as well as single bonds; and,
optionally, one or more of the following components:
(B) a concentration of a component of one or more surfactants that consists
of molecules that are not part of component (A);
(C) water;
(D) a component of pH adjusting agent that is not part of any of components
(A), (B), and (C);
(E) a component of preservative material that is not part of any of
components (A), (B), (C), and (D);
(F) a component of viscosity adjusting agent that is not part of any of
components (A), (B), (C), (D), and (E); and
(G) a component of humectant material that is not part of any one of
components (A), (B), (C), (D), (E), and (F).
Component (A) as described above is normally the predominant constituent,
with the possible exception of water, in a liquid composition used
according to the invention to form a glossy and specularly reflective
liquid film. The combination of hydrophilic and hydrophobic portions in
molecules constituting component (A) is believed to make them particularly
suitable for forming the bulk of the glossy and specularly reflective
liquid film required in a process according to the invention.
Additionally, molecules of this type with sufficiently high molecular
weights to give them low volatility at normal ambient human comfort
temperatures, i.e., 18-25.degree. C., to favor long open times, are
readily available commercially.
Because of their low cost and ready availability, particularly preferred
groups of materials for component (A) are (i) those materials, denoted
herein as "glycols" and "glycol polymers", the molecules of which conform
to the chemical formula HO--(C.sub.n H.sub.(2n+1-m) O.sub.m).sub.p --H,
where n is an integer from 2 to 6, preferably from 2 to 4, more preferably
2 or 3, most preferably 2; m, for each molecule, is an integer with a
value not greater than the value of n for the same molecule, preferably
not greater than 2 and more preferably, unless p=1, exactly 1; and p, for
each molecule, is an integer with a value of 1 for glycols and a value of
at least 2 for glycol polymers (for glycol polymers, any one or more of n,
m, and p may have an average non-integral value for component (A) as a
whole); and (ii) the mono- and di-ethers of such glycols and glycol
polymers, said ethers having terminal alkyl moieties with from 1 to 6,
preferably from 1 to 4, more preferably from 1 to 3, carbon atoms. If p is
two or more, the values of n and m may be the same or different from one
to another of the p instances of the moiety --C.sub.n H.sub.(2n+1-m)
O.sub.m -- in each molecule, and if n is greater than 2, all except two of
the carbon atoms in each --C.sub.n H.sub.(2n+1-m) O.sub.m -- moiety may be
out of the continuously chemically bonded chain that is necessarily
present in a moiety --C.sub.n H.sub.(2n+1-m O.sub.m --C.sub.n'
H.sub.(2n'+1-m') O.sub.m' -- which is present in each molecule of a glycol
polymer. (If n is always four or greater, some of the carbon atoms present
in each --C.sub.n H.sub.(2n+1-m) O.sub.m -- moiety must be out of the
continuously chemically bonded chain in at least one --C.sub.n
H.sub.(2n+1-m O.sub.m --C.sub.n' H.sub.(2n'+1-m') O.sub.m' -- moiety in
each molecule, in order for the molecule to satisfy the conditions for
belonging to component (A).) Polymers of ethylene and/or propylene
glycol(s) in which there are at least two glycol units are, along with
glycerin and propylene glycol itself, particularly preferred constituents
for component (A).
In order to achieve an optimum balance between volatility and tendency of
an initially formed glossy and specularly reflective liquid film to
solidify and/or develop haziness during drying, the weight average
molecular weight of any glycol polymers portion of component (A) in the
film, which glycol polymers portion may or may not constitute all of
component (A), preferably is at least, with increasing preference in the
order given, 100, 150, 200, 250, 300, 325, 350, 375, or 395 and
independently preferably is not more than, with increasing preference in
the order given, 4000, 3000, 2000, 1750, 1500, 1250, 1000, 750, or 500.
(Haziness in the film is disadvantageous because it may, and if severe
enough will, make the desired defect detection impossible as long as it
persists. In some instances, it has been observed that an initially
transparent liquid coating becomes hazy during drying and then becomes
transparent again after further drying. Compositions with this property
are often acceptable for use according to the invention, but are generally
not preferred, because any period of haziness subtracts from the effective
open time available with the particular liquid composition. Substantial
fractions of glycol polymers with molecular weights above 1000, which,
especially if they are homopolymers of ethylene glycol, are likely to be
solid rather than liquid at normal ambient temperature, have been observed
to favor development of haziness for at least a brief interval during
drying of the glossy and specularly reflective liquid films used as part
of a process according to the invention.)
Another type of generally highly satisfactory and commercially available
materials for component (A) as described above are ethers, particularly
monoethers, of glycol polymers. Non-limiting examples of these materials
include diethylene glycol monobutyl ether, tripropylene glycol monomethyl
ether, and dipropylene glycol mono-n-propyl ether. For these materials, a
somewhat lower average molecular weight than for the glycol polymers
themselves is preferred. Specifically, the weight average molecular weight
of any ethers of glycol polymers present in component (A) of a composition
to be used according to the invention to form a glossy and specularly
reflective liquid film preferably is at least, with increasing preference
in the order given, 80, 100, 120, 140, 150, 160, 170, 180, or 185 and
independently preferably is not greater than, with increasing preference
in the order given, 500, 400, 350, 300, 280, 260, 250, 240, 230, or 225.
Among the monomeric glycols as defined above that may be constituents of
component (A) according to the invention, glycerin is most preferred,
propylene glycol is nearly as preferred as glycerin, and ethylene glycol
is distinctly less preferred, although suitable.
A normally preferred at least partial constituent of component (A) as
described above is material with stronger surfactant properties than most
of the glycols, glycol polymers and their ethers. One especially preferred
type of such materials is constituted of molecules that, in addition to
having in each molecule at least one continuously chemically bonded chain
or ring of atoms in which there are at least two carbon atoms and at least
two heteroatoms, as required to be part of component (A), also have at
least one hydrophobe moiety that satisfies all of the following
conditions: (i) it has not more than two open valences; (ii) it has a
number of carbon atoms that is at least, with increasing preference in the
order given, 8, 10, 12, 14, or 16; (iii) it contains no atoms other than
carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur, and halogens and
preferably, primarily for reasons of economy, contains no halogen atoms or
more preferably no halogen, phosphorus, or sulfur atoms; (iv) if it
contains any atoms of nitrogen, oxygen, phosphorus, or sulfur, it contains
such atoms in a number having a ratio to the number of carbon atoms in the
same moiety that is not more than, with increasing preference in the order
given, 0.34:1.0, 0.30:1.0, 0.25:1.0, 0.20:1.0, 0.15:1.0, 0.10:1.0, or
0.05:1.0. (It should be noted that block copolymers of propylene oxide and
ethylene oxide, if the blocks of polypropylene oxide are long enough, can
satisfy this definition if they have surfactant properties, i.e., if they
cause a reduction in the surface tension of water when dissolved therein.)
A particular type of surfactant constituent of component (A) that is
preferred in certain instances is one in each molecule of which there is a
substituted imidazoline moiety (which itself satisfies the structural
formula conditions for being a part of component (A)), with a hydrophobic
moiety attached to the carbon atom in the imidazoline moiety that is
directly bonded to both nitrogen atoms in the imidazoline moiety, and
preferably also at least one, or more preferably two, substituent moieties
bonded to nitrogen atom(s) in the imidazoline moiety, these substituent
moieties being selected from the group consisting of (i) hydroxyalkyl
moieties, preferably hydroxymethyl and hydroxyethyl moieties, more
preferably the latter; (ii) carboxyalkyl moieties (i.e., moieties derived
from carboxylic acids by removing from each molecule thereof one hydrogen
atom that is not the one that is part of the characteristic --COOH moiety
of a carboxylic acid), preferably those derived from propanoic or 2-methyl
propanoic acid, more preferably the former; and (iii) carbonate moieties.
2-Alkylimidazoline moiety containing surfactants of this type often impart
two useful properties to compositions for forming glossy and specularly
reflective liquid film in a process according to the invention: good
wetting of most engineering plastic surfaces and freedom from haziness at
any stage of drying. However, these surfactants are considerably more
expensive than most other suitable surfactants that can constitute part of
component (A) as defined above, and therefore, at least for reasons of
economy, preferably are used, if at all, only when and to the extent that
these advantages are needed. The carboxyalkyl moiety may be free acid or a
salt, preferably a salt with an alkali metal cation. One particularly
preferred embodiment of this type of surfactant is one available
commercially from Mona Industries as MONATERIC.TM. Cy Na 50 and reported
by its supplier to be a 50% solution in water of the sodium salt of
3-[1-(2-hydroxyethyl)-2-capryl-3-imidazolinyl] propanoic acid. Another
particularly preferred embodiment of this type of surfactant is one
available commercially from Lonza, Inc. as AMPHOTERGE.TM. KJ-2 and
reported by its supplier to be a 40% solution in water of substituted
imidazoline dicarbonate molecules.
Component (A) in total preferably constitutes at least, with increasing
preference in the order given, 5.0, 7.0, 8.0, 9.0, 10.0, or 11.0, and
unless substantially all of component (A) has surfactant properties, still
more preferably constitutes, with increasing preference in the order
given, at least 12.0, 12.3, 12.6, 12.9, 13.2, 13.5, 13.7, or 13.9% of a
total composition to be used for forming a glossy and specularly
reflective liquid film in a process according to the invention.
Independently, surfactants belonging to component (A) preferably
constitute at least, with increasing preference in the order given, 0.15,
0.30, 0.50, 0.70, 0.80, 0.90, 1.0, or 1.1% of a total composition to be
used for forming a glossy and specularly reflective liquid film in a
process according to the invention, and, if the surfactant portion of
component (A) does not include alkyl imidazoline moiety containing
surfactants in an amount of at least, with increasing preference in the
order given, 0.50, 0.60, 0.70, 0.80, 0.90, or 1.0% of the total
composition, more preferably constitutes at least, with increasing
preference in the order given, 2.0, 3.0, 3.5, 4.0, 4.5, 5.0, or 5.5% of
the total composition. Also and independently, molecules selected from a
group consisting of (i) homopolymers of ethylene glycol, (ii) monoethers
of homopolymers of ethylene glycol, monoethers of homopolymers of
propylene glycol, and monoethers of copolymers of both ethylene and
propylene glycols, and (iii) glycerin and propylene glycol preferably
constitute at least, with increasing preference in the order given, 3.0,
4.5, 6.0, 7.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, or 12.5% of a total
composition to be used for as forming a glossy and specularly reflective
liquid film in a process according to the invention, and, unless at least,
with increasing preference in the order given, 0.5, 1.0, 1.5, 2.0, 2.5,
3.0, 4.5, 6.0, 7.5, 9.0, 9.5, or 10.0% of the total composition consists
of glycerin, propylene glycol, and mixtures thereof, molecules selected
from a group consisting of (i) homopolymers of ethylene glycol and (ii)
monoethers of polymers of ethylene and propylene glycols preferably
constitute at least, with increasing preference in the order given, 12,
15, 17, 19.0, or 20.0% of the total composition. Independently of one
another and of any other stated preferences: molecules selected from the
group consisting of (i) homopolymers of ethylene glycol and (ii)
monoethers of polymers of ethylene and propylene glycols preferably
constitute not more than, with increasing preference in the order given,
50, 40, 35, 30, or 25% of the total composition; molecules selected from
the group consisting of glycerin and propylene glycol preferably
constitute not more than, with increasing preference in the order given,
40, 30, 25, 22, 19, 17, or 15 percent of the total composition;
surfactants belonging to component (A) preferably constitute not more
than, with increasing preference in the order given, 40, 30, 20, 15, 12,
10, 8, or 6% of the total composition; and component (A) in total
constitutes not more than, with increasing preference in the order given,
90, 80, 70, 60, 50, 40, or 31% of the total composition, all of the
preferences stated in this sentence being primarily for reasons of
economy.
Ordinarily it is preferable if all of the surfactant in a composition to be
used for forming a glossy and specularly reflective liquid film in a
process according to the invention is part of component (A). In this
instance, component (B) as described above is not needed and therefore
preferably is not used. However, an antifoam agent that does not satisfy
the conditions for belonging to component (A) may be needed in certain
instances, as may other conventional surfactants, in order to achieve
adequate and rapid wetting of the surface to be examined for defects.
Highly fluorinated surfactants, for example, may be needed for plastics
that have very low surface energies and are therefore difficult for most
water-based compositions to wet. When fluorinated surfactants are needed
for good wetting, they are preferably selected from the group consisting
of fluorinated, preferably perfluorinated, alkyl substituted phosphonic,
phosphinic, sulfonic, and sulfinic acids, more preferably phosphonic and
phosphinic acids, and salts of these acids. When fluorinated surfactants
are used, their total concentration in the liquid used to form a glossy
and specularly reflective film in a process according to the invention
preferably is at least, with increasing preference in the order given,
0.0020, 0.0040, 0.0060, 0.0080. 0.010, 0.012, 0.014, 0.016, or 0.018% and
independently, primarily for reasons of economy, preferably is not more
than, with increasing preference in the order given, 0.5, 0.3, 0.20, 0.10,
0.080, 0.060, 0.040, or 0.030%.
Care should be taken to avoid utilizing any surfactants that, in the
concentrations of them used, are likely to penetrate into the interior of
the substrate having a surface being tested and thereby physically weaken
the substrate and/or weaken the adhesion of subsequently desired finishes
to the surface. Preferably a composition according to the invention does
not substantially swell or dissolve the organic solid to be tested. This
property can conveniently be checked by placing a few drops of the
composition on a sample of the surface to be tested, allowing the drops to
remain in place on the surface for at least eight hours, and then rinsing
off the composition and examining the surface for visible damage. Most
preferably, no change in the surface to be tested is observable with the
unaided eye after this test. In some cases, however, a faint haziness is
observable in the tested surface after such an extended test, without any
significant harm to the performance of the composition that causes the
haze in practical use. Compositions that leave the surface visibly
swollen, blistered, and/or tacky are preferably avoided.
Individual components can be tested in the same way as described above for
the compositions, if the individual components are liquid, or in
concentrated solutions if the components are solids at the intended
temperature of use. Most surfactants tested in highly concentrated form
have been found to promote swelling of some surfaces that might be tested
in a process according to the invention, but alkyl polyglucosides are
exceptional among strongly effective surfactants in lacking any such
detrimental tendency. If a surfactant that is not part of component (A) as
described above is needed or preferred in a composition for forming a
substantially uniform and specularly reflective liquid film in a process
according to the invention, therefore, this class of surfactants is
preferred if the tendency for damage to the surface being tested needs to
be minimized. However, as noted in the examples below, some surfactants,
such as MONATERIC.RTM. Cy Na 50, that can safely be used at moderate
concentrations cause damage when tested at a high concentration on at
least some substrates that might be tested according to this invention.
Ordinarily water is a preferred component of a composition to be used for
forming a glossy and specularly reflective liquid film in a process
according to the invention, if for no other reason than reducing the cost
of the composition. Thus, normally water preferably constitutes the
balance of any amount of a composition to be used for forming a glossy and
specularly reflective liquid film in a process according to the invention
that is not specified to be some other substance. However, if a
particularly long open time is needed for any reason, water may be
omitted.
A composition to be used for forming a glossy and specularly reflective
liquid film in a process according to the invention preferably has a pH
value in a very mildly acidic to mildly alkaline range. More particularly,
the pH preferably is at least, with increasing preference in the order
given, 5.5, 6.0, 6.3, 6.6, 6.9, 7.1, 7.3, 7.6, 7.9, or 8.2 and, if the
composition does not contain more than, with increasing preference in the
order given, 5.0, 4.0, 3.0, 2.0, or 1.0% of glycol polymers and/or glycol
polymer ethers, more preferably is at least, with increasing preference in
the order given, 8.5, 8.8, 9.1, or 9.4; independently the pH preferably is
not more than, with increasing preference in the order given, 11.0, 10.5,
10.2, 9.9, or 9.6, and, if the composition contains at least, with
increasing preference in the order given, 6, 8, 10, 12, 14, or 16% of
glycol polymers or glycol polymer ethers more preferably is not more than
9.3, or still more preferably not more than 9.0. In order to achieve a
preferred pH, an alkalinizing pH adjusting component (D), in addition to
any materials in components (A) through (C) as defined above, is generally
needed. Aqueous ammonia or an amine is generally preferred for this
purpose. If the pH is within its most preferred range, ammonia may
normally be used without danger of a serious odor nuisance, but if more
alkaline pH values are desired, a relatively non-volatile amine,
preferably an amine with at least two and preferably three substituent
moieties selected from the group consisting of hydroxymethyl,
hydroxyethyl, and hydroxypropyl moieties, most preferably hydroxyethyl,
are preferably used instead to avoid a malodorous composition. If an
acidizing pH adjusting agent should be needed, numerous ones are known to
those skilled in the art.
Normally, the presence of a preservative, component (E) as described above,
in a composition to be used for forming a glossy and specularly reflective
liquid film in a process according to the invention is highly preferred if
the composition is to be stored in an open container during use as it
usually is, because some commonly air-borne microorganisms with malodorous
and/or otherwise disagreeable, e.g., surface-blemishing, metabolic
products are readily attracted to and nourished by most of the
constituents normally used for component (A). Any preservative with
sufficient protective value against ambient micro-organisms may be used,
provided that it does not adversely affect the wetting and/or specularly
reflective properties of the liquid films formed in a process according to
the invention. Preservatives containing isothiazolin-3-one moieties have
been found particularly suitable, more particularly a mixture of the
commercial products KATHON.TM. 886 MW and 893 MW preservatives from Rohm
and Haas Co. of Philadelphia, Pa. KATHON.TM. 886 MW is reported by its
supplier to contain 10-12% of 5-chloro-2-methyl-isothiazolin-3-one and
3-5% of 2-methyl-isothiazolin-3-one as its preservative active ingredients
along with 14-18% of magnesium nitrate and 8-10% of magnesium chloride,
all in water solution with water as the balance, and to be particularly
effective against bacteria. KATHON.TM. 893 MW is reported by its supplier
to contain 45-48% of 2-n-octyl-4-isothiazolin-3-one and 52-55% of
propylene glycol. Accordingly, a composition to be used to form a glossy
and specularly reflective liquid film in a process according to the
invention preferably contains, independently for each material noted, at
least, with increasing preference in the order given: 0.50, 0.75, 0.90,
1.00, 1.10, 1.20, 1.30, or 1.37 parts per million by weight of the total
composition, hereinafter usually abbreviated as "ppm", of
5chloro-2-methyl-isothiazolin-3-one; 0.10, 0.20, 0.25, 0.30, 0.35, 0.40,
0.45, or 0.48 ppm of 2-methyl-isothiazolin-3-one; and 0.75, 1.00, 1.50,
2.00, 2.25, 2.45, 2.60, 2.75, or 2.90 ppm of 2-n-octyl-isothiazolin-3-one.
Also, independently of other preferences and independently for each
material noted, a composition to be used to form a glossy and specularly
reflective liquid film jn a process according to the invention preferably
contains not more than, with increasing preference in the order given: 10,
8, 6, 4.0, 3.0, 2.5, 2.0 or 1.5 ppm of
5-chloro-2-methyl-isothiazolin-3-one; 5, 3, 2.0, 1.5, 1.0, 0.8, 0.6, or
0.54 ppm of 2-methyl-isothiazolin-3-one; and 25, 15, 10, 8, 6, 5.0, 4.0,
3.7, 3.4, 3.2, or 3.0 ppm of 2-n-octyl-isothiazolin-3-one, all of the
preferences stated in this sentence being primarily for reasons of
economy.
The rheological properties of a composition to be used for forming a glossy
and specularly reflective liquid film in a process according to the
invention should be such as are needed to keep the film formed from
draining from the surface during the open time needed for examination.
Ordinarily, a satisfactory rheology can be achieved by proper selection of
the materials constituting component (A) as described above when
substantial amounts of polyethylene glycols are included among the
materials constituting component (A). If needed, however, any other
rheology modifying agent may be added to such a composition to be used for
forming a glossy and specularly reflective liquid film in a process
according to the invention without departing from the spirit of the
invention, provided that the rheology modifying agent used does not
adversely affect the specular reflection properties of the film formed.
Acrylic acid polymers, natural gums, synthetic carbohydrate polymers, and
other water soluble materials of this kind are normally preferred when
needed. When most of component (A) is selected from glycerin and propylene
glycol, as is preferred in one embodiment of the invention, a rheology
modifying agent is preferably used as well. Particularly preferred is a
polyacrylic acid thickening agent; such materials are readily available as
aqueous solutions, dispersions, or both dispersions and solutions. When
this type of thickening agent is used, its amount (as active polymer only)
preferably is at least, with increasing preference in the order given,
0.004, 0.008, 0.016, 0.025, 0.030, 0.035, 0.040, 0.042, 0.044, or 0.046%
of the total glossy and specularly reflective liquid film and
independently preferably is not more than, with increasing preference in
the order given, 0.30, 0.20, 0.10, 0.08, 0.060, 0.055, or 0.050% of the
total glossy and specularly reflective liquid film.
Humectant component (G) is not normally needed or advantageous in a
composition to be used for forming a glossy and specularly reflective
liquid film in a process according to the invention, particularly if
monomeric glycols as described above, most of which have humectant
properties, are included as part of component (A). However, other
humectants, such as calcium chloride, may also be added to the
compositions if desired, particularly to achieve very long open times.
For a variety of reasons, almost always including at least the economic
reason of avoiding an unnecessary component, it is preferred that
compositions to be used for forming a glossy and specularly reflective
liquid film in a process according to the invention should be
substantially free from many ingredients, including some used in the prior
art in compositions for detecting defects on metal surfaces. Specifically,
independently for each preferably minimized component listed below,
compositions to be used for forming a glossy and specularly reflective
liquid film in a process according to the invention preferably contain,
with increasing preference in the order given, no more than 1.0, 0.35,
0.10, 0.08, 0.04, 0.02, 0.01, 0.001, or 0.0002% of each of the following
constituents, except for and to the extent that these constituents may be
part of optional components explicitly described hereinabove: hexavalent
chromium, cyanide ions, nitrite ions, coordinate complexing agents for
divalent or higher valent metal cations; dispersed or emulsified chemical
substances that are not soluble in water to an extent of at least, with
increasing preference in the order given, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0,
7.0, 8.0, or 9.0%; inorganic compounds of any of the halogen elements; and
any compounds containing any one of the elements boron, beryllium, and all
elements, except for alkali metals and halogens, that have an atomic
number greater than or equal to 19.
Substrate surfaces that can be effectively inspected according to this
invention include, but are not limited to, polyester sheet molding
compound (hereinafter usually abbreviated as "SMC"), both primed and
unprimed, the latter also often being called "raw"; poly{vinyl chloride}
(hereinafter usually abbreviated as "PVC") homopolymers and copolymers;
polyurethane and polyurea plastic surfaces such as those of objects made
commercially by injection molding from these plastics; terpolymers of
acrylonitrile, butadiene, and styrene (hereinafter usually abbreviated as
"ABS"); poly{phenylene oxide} (hereinafter usually abbreviated as "PPO")
and copolymers of "phenylene oxide" with other materials such as
polyamides; polycarbonate (hereinafter usually abbreviated as "PCO")
polymers and copolymers; and thermoplastic polyolefins (hereinafter
usually abbreviated as "TPO"). The invention is especially advantageously
applicable to primed and unprimed SMC and TPO surfaces, most preferably to
TPO.
Application of the defect detecting composition to the surface to be tested
may be made by any method that forms a satisfactory film. Spraying, roll
coating, brushing, wiping with a saturated absorbent material such as
cloth, and squeegeeing are all suitable methods. However, some methods,
such as the use of perforated saturated cloth, introduce small air bubbles
into the coating formed. These are generally undesirable, as they may
interfere with observation of the consistent gloss that characterizes a
defect free surface. However, highly satisfactory applications can be made
with cloth or non-woven webs that do not have openings larger than, with
increasing preference in the order given, 4.0, 3.0, 2.0, 1.0, 0.7, 0.4, or
0.2 millimeter in their largest dimension. If a highly absorbent web of
this type is completely saturated, it is likely to apply a wastefully
large amount of the defect detecting composition. Therefore, it is
preferred that an absorbent material used as a carrier for the defect
detecting composition in a process according to this invention, at the
time when contacted with a substrate to be tested, contains a mass of the
defect detecting composition that is not more than, with increasing
preference in the order given, 5.0, 3.0, 2.0, 1.7, 1.5, 1.35, 1.25, 1.15,
1.10, 1.05, or 1.00 times the mass of the absorbent material itself.
Practice of this invention may be further appreciated from consideration of
the working and comparison examples described below.
COMPARISON EXAMPLE GROUP A
Kerosine, a hydrocarbon solvent with an initial boiling point of about
175.degree. C. that has been used on metal surfaces for purposes analogous
to those of this invention on non-metal surfaces, does not spread
satisfactorily over TPO and SMC plastics to form a suitably glossy and
speculary reflective film, and/or does not stay in place as much as five
minutes when a sample coated with it is suspended with the coated surface
vertical.
Similarly, a mixture of naphtha and mineral spirits has been used for metal
surfaces, but it is entirely unsatisfactory for many plastic surfaces,
because it can be absorbed by the plastic surfaces and be very difficult
to remove from them, as is necessary for satisfactory further processing
of the plastic objects having surfaces contaminated with these volatile
compounds. In addition, this material has a flash point below 38.degree.
C. and therefore is a substantial fire hazard.
GROUP 1--WITH COMPOSITIONS GENERALLY INCLUDING GLYCOL POLYMERS AND/OR
GLYCOL POLYMER ETHERS
Compositions for this group are given in Table 1 below. The performance of
the compositions shown in Table 1 on various plastic substrates, in most
instances including TPO, which is generally considered one of the most
difficult of the engineering plastics to wet consistently, is as follows:
Composition 1.1 wets some plastics well and others such as TPO, on which it
is susceptible to Swiss-cheese-dewetting, less well. It becomes non-glossy
within 15 rain after application on any substrate tried. It washes off
easily with water, even after losing its gloss, and has no visible effect
on the washed plastic surface.
Composition 1.2, which is considerably more concentrated in glycol polymers
and in some of the surfactants but has the same ingredients as Composition
1, behaves essentially as does Composition 1.1.
Composition 1.3 is one of the best and most economical of this group, with
an open time of at least 3-4 minutes on any substrate tried, including TPO
and bare and primed SMC, on the latter of which it dries without ever
collecting into drops.
Composition 1.4 has the same ingredients as Composition 1.3, except that
the glycol polymers are omitted. It provides excellent initial properties
but has no more than 2 minutes of open time, demonstrating an advantage of
the glycol polymers.
Composition 1.5 has the same ingredients as Composition 1.3, but with
considerably higher concentrations of the glycol polymers. It is
considerably more viscous than and forms a thicker coating than
Composition 1.3, but the open time is not significantly improved over
Composition 1.3, demonstrating the lack of additional benefit from greater
concentrations of glycol polymers.
Compositions 1.6 and 1.7 are the most troublefree of this group but are
more expensive than Composition 1.3, which often gives quite adequate
results. Compositions 1.6 and 1.7 both achieve very high quality coatings
which do not show Swiss-cheese-dewetting
TABLE 1
__________________________________________________________________________
LIQUID COMPOSITIONS FOR POSSIBLE USE IN DETECTING DEFECTS IN PLASTIC
SURFACES
Concentration of Ingredient in Composition Number:
Ingredient and Concentration Unit
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
__________________________________________________________________________
Polyethylene glycol, 1000 Mo Wg, %
5.7
12 9.7 25 10
Polyethylene glycol, 400 Mo Wg, %
1.1
12 9.7 25 17 10
96% Glycerin, % 15
Dipropylene glycol, mono-n-propyl ether, %
10
MONATERIC .TM. Cy Na 50 surfactant sol., %
3.1 2.5 2.0
PLURONIC .TM. L-64 surfactant, %
3.5
2.6
4.0
7.0
4.0 1.7
ANTAROX .TM. LF-344 surfactant, %
0.5
0.4 0.3
ANTAROX .TM. LF-224 surfactant, %
1.7
1.7
1.7
TRITON .TM. N-57 surfactant, %
0.3
0.3
0.3
PLURAFAC .TM. RA-40 surfactant, % 30
PLURAFAC .TM. RA-30 surfactant, % 2.2
PLURAFAC .TM. RA-20 surfactant, % 0.9
TRITON .TM. DF-12 surfactant, % 0.4
Dee Fo .TM. 97-3 antifoam agent, % 0.04
FLUOWET .TM. PL80 surfactant, % 0.09
28% Ammonia in water, ppt
0.5
0.5
0.5
0.5
0.5 0.5
Triethanol amine, % 0.7
1.1
KATHON .TM. 886 MW, ppm
13 13 13 13 13 13 13 13
KATHON .TM. 893 MW, ppm
6.4
6.4
6.4
6.4
6.4
6.4
6.4
6.4
ACUSOL .TM. 810 thickening agent 0.6
__________________________________________________________________________
Abbreviations and Other Notes for Table 1
"Mo Wg" means "weight average molecular weight"; "sol." means "solution i
water"; "ppt" means "parts per thousand". A blank space in a cell of the
upper part of this and any subsequent table indicates that none of the
material named in the row containing the cell was added to the
composition.
Water constituted the unspecified balance of the compositions shown in
this table.
PLURONIC .TM. L64 and PLURAFAC .TM. RA40, 30, and 20 surfactants were
obtained commercially from BASF Corp. and were reported by their supplier
to be block copolymers of propylene and ethylene oxide for the first
listed and modified oxyethylated straight chain alcohols for the
remainder. ANTAROX .TM. LF344 and LF 224 were obtained commercially from
RhonePoulenc and were reported by their supplier to be modified linear
aliphatic polyether and alkoxylated alcohol # respectively.
TRITON .TM. N57 and DF12 surfactants were obtained commercially from Unio
Carbide and are reported by their supplier to be
nonylphenoxypolyethoxyethanol and modified polyethoxylated straight chain
alcohol respectively. FLUOWET .TM. PL80 surfactant was obtained
commercially from Minnesota Mining and Manufacturing Co. and was reported
by its supplier to be perfluorinated alkyl phosphonic and phosphinic
acids.
ACUSOL .TM. 810 thickening agent was obtained commercially from Rohm &
Haas and was reported by its supplier to be a 15-19% solution in water of
polyacrylic acid. Dee Fo .TM. 973 was obtained commercially from Ultra
Additives, Inc., Paterson, New Jersey (no chemical information about it
was given, except that it contained 4% petroleum solvent.).
on any of the substrates TPO and bare and primed SMC, have at least 5
minutes of open time, remain glossy even after drying, and can readily be
removed by water rinsing.
Composition 1.8 is susceptible to such severe Swiss-cheese-dewetting that
it has no more than 90 seconds of effective open time.
GROUP 2--WITH COMPOSITIONS INCLUDING MONOMERIC GLYCOLS AS PREDOMINANT
CONSTITUENTS OF COMPONENT (A)
Compositions for this group are shown in Table 2 below.
TABLE 2
__________________________________________________________________________
MORE LIQUID COMPOSITIONS FOR POSSIBLE USE IN DETECTING DEFECTS IN
PLASTIC SURFACES
Parts by Weight of Ingredient in Composition Number:
Ingredient 2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
__________________________________________________________________________
Deionized Water 120
120
138
126
135
135
135
156
AMPHOTERGE .TM. KJ-2 surfactant
7.5
7.5
1.5
1.5
4.5
4.5
4.5
4.5
96% Glycerin 21.5
21.5
21.5 21.5
21.5
21.5
Ethylene glycol 21.5
FLUOWET .TM. PL80 surfactant, %
0.10
0.01
0.03
0.03
0.03
0.03 0.03
ACUSOL .TM. 810 thickening agent
0.9
0.9
0.9
0.9
0.45
Other Characteristics of Composition:
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
Concentration of KATHON .TM. 886 MW, ppm:
13 13 13 13 13 13 13 13
Concentration of KATHON .TM. 893 MW, ppm:
6.4
6.4
6.4
6.4
6.4
6.4
6.4
6.4
pH of the Composition:
9.4
9.4
7.9
n.m.
9.4
n.m.
n.m.
n.m.
__________________________________________________________________________
Abbreviation for Table 2
"n.m." means "not measured".
Characteristics in use of the compositions shown in Table 2 are as follows:
Compositions 2.1 and 2.2 flow out well on both SMC and TPO substrates,
producing a glossy film that persists for at least several hours. On SMC,
a hydrophilic slick area is produced after the initially formed film,
having been in place for several hours, is rinsed away with water. No such
hydrophilic slick forms on TPO substrate.
Both of Compositions 2.3 and 2.4 flow out readily onto both SMC and TPO and
have open times of at least 30 minutes. However, after storage of the
coated part for 16 hours, with exposure to the ambient atmosphere,
Composition 2.4 has a dry look, while Composition 2.3 still looks glossy.
Most residues from both Compositions are easily removed from the
substrates after this 16 hour period of exposure, but, as with
Compositions 2.1 and 2.2, a hydrophilic slick remains on the SMC substrate
only after rinsing, while the rinsed substrates are still wet. If the
rinsed substrates are dried in an oven, no visible evidence of the
hydrophilic slick remains, but the substrates do not wet easily with
solvent-based paint in areas exposed to composition 2.4; little or no such
lyophobicity is observed for the substrates exposed to Composition 2.3,
indicating that glycerin causes less difficulty in this respect than does
ethylene glycol.
Composition 2.5 on a TPO substrate, whether applied with a cotton swab or
by flowing on, forms a suitable glossy film without any visually
perceptible dewetting and with an open time of at least an hour.
Composition 2.8 acts in the same way as 2.5, except that the film from
Composition 2.8 is dull rather than glossy after a few minutes exposure to
the ambient atmosphere. Composition 2.7 dewets rapidly by "rolling up" of
liquid from the edges of the coated area toward its center, after
application by either method. Composition 2.6 is susceptible to rolling up
when applied with a cotton swab but not when flowed on, a method that
forms a thicker coating layer. After washing and drying, all of the
surfaces treated with one of these four Compositions were free from
visible residue and otherwise undamaged by the Compositions.
GROUP 3--TESTING COMPONENTS FOR ADVERSE EFFECTS ON SUBSTRATES
In a first subgroup, various candidate components were tested for possible
damage to substrates. A few drops of each component were placed on the
surface of test substrates as described further below and allowed to stand
for 8 hours in air at 49.degree. C. and 25% RH; then the residue of the
liquid was rinsed away with 60 seconds of water spraying. The substrates
tested and their identifying numbers are:
1. U04AD045 gray primer from BASF Corporation
2. Premix gray SMC primer from Siebert-Oxidermo Corporation
3. XENOY.TM. polycarbonate/polyester blend plastic from General Electric of
Schenectady, N.Y.
4. Red Spot Paint Company type 206LE 2K Polyurethane Topcoat, white
5. "80.degree. Gloss" RIM primer from PPG Corporation of Pittsburgh, Penn.
The components tested and their identifying abbreviations (in parentheses)
are: APG.RTM. 225 (Apg2) and APG.RTM. 325 (Apg3) from Henkel Corp. of
Plymouth Meeting, Pennsylvania; Triton.RTM. DF-16 (DF-16); MAKON.RTM.
NF-12 (NF-12); MONATERIC.RTM. Cy Na 50 (MON) and PLURONIC.RTM. L63 (PLU).
The results are shown in Table 3. Only glycerin and the APG.RTM.
surfactants were generally free from any evidence of damage when applied
in full strength as in this test, but many of the other components listed
can be used in the amounts preferred for compositions to be used to form a
substantially uniform and specularly reflective liquid film in a process
according to this invention, without causing any unacceptable damage to
the surfaces tested.
In a second subgroup, the following components and component mixtures were
tested in exposure for about 16 hours on raw SMC: (1) glycerin alone, (2)
AMPHOTERGE.TM. KJ-2 surfactant alone, (3) ACCUSOL.TM. 810 rheology
modifying agent alone, (4) FLUOWET.TM. PL-80 surfactant alone, (5)
glycerin and the rheology modifying agent mixture, (6) glycerin and KJ-2
surfactant mixture, and (7) glycerin and PL-80 surfactant mixture. After
rinsing with warm tap water, (1), (2), and (6) had no visible effect on
the substrate; (3) and (5) hydrophilicized the SMC surface arid (5)
slightly darkened it; and (4) and (7) both hydrophilicized the SMC surface
and changed its color, (7) even leaving a whitish residue on the surface.
TABLE 3
______________________________________
RESULTS OF TESTS OF SURFACTANTS FOR DAMAGE TO
SUBSTRATES
Com-
pon- Evidence of Damage on Substrate No.:
ent 1 2 3 4 5
______________________________________
Apg2 trace none none none none
Apg3 none none none none none
DF 16 slick shiny raised
haze whitish raised
bump
area damage bump
MON trace trace haze slight raised
raised area
damage area
NF 12 glossy glossy, haze raised area
raised area
raised slightly damage
slick raised
PLU glossy glossy, raised area
raised area
raised area
raised slightly
slick raised
______________________________________
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