JPS5927966A - Coating composition having chipping resistance - Google Patents

Abstract

PURPOSE:To provide the titled coating compsn. capable of yielding good appearance even when highly dense films are formed by single coating and baking, by incorporating a polyhydroxy resin and an amino resin or blocked isocyanate, with a particular amt. of terpene contained. CONSTITUTION:A polyhydroxy resin and an amino resin or blocked isocyanate are incorporated, in which 1-30wt%, based on solids of the polyhydroxy resin, terpene or its derivatives are contained. Polybasic acids, polyols and, if necessary, polyhydroxy carboxylic acids, fatty acids, or fats or oils are used as the polyhydroxy resins, and the use of polyesters and alkyds yielded by condensation at 150-250 deg.C with an equivalent excess of hydroxyl groups over carboxyl groups is particularly pref. As blocked isocyanates, those which are formed by reacting polyisocyanates with blocking agents and eliminating isocyanate groups active at ordinary temp. are used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a chipping-resistant paint composition for automobiles and the like.

More specifically, the present invention relates to a coating composition that is capable of forming a coating film that exhibits excellent chipping resistance without causing wrinkles even when a high film thickness is formed in a single application and baking process.

In recent years, in order to prevent corrosion of automobile bodies, it has been desired to improve the surface 1 chipping properties of coating films.

That is, it has been pointed out that while the car is running, pebbles and the like are thrown around and damage the paint film, causing the underlying metal to rust from the damaged areas, accelerating the corrosion of the car body.

Therefore, as one of the coating functions, it is desired to develop a chipping-resistant paint that is resistant to damage even by collisions with pebbles, etc., can prevent corrosion of metal car bodies, and does not have paint film defects such as underarms as an automotive paint. It is rare.

However, in the past, one-time application and baking for the purpose of improving chipping resistance caused wrinkles and significantly damaged the appearance, so in order to maintain a good appearance, it was necessary to apply a relatively thin film of about 50 μm. The actual situation was that a film had to be formed and sufficient chipping resistance could not be achieved.

In order to prevent damage to the paint film caused by collisions with pebbles, etc., it is advantageous to absorb the impact energy with a thick paint film, and anti-depping paints that can form a thick paint film are highly effective. It is expected to have excellent chipping resistance. Note that the term "high film thickness" as used herein means a film thickness of approximately 60 to 500 microns.

The purpose of the present invention is to form a coating film with a high thickness by one application and firing, which will not cause wrinkles, have a good appearance, and exhibit sufficient chipping resistance for practical use. An object of the present invention is to provide a paint composition for use in paints.

That is, the present invention comprises a polyhydroxy resin and an amino resin or a blocked isocyanate, and terpene or a derivative thereof is added in an amount of 1 to 1 to 100% based on the solid content of the polyhydroxy resin.
The object of the present invention is to provide a chipping-resistant coating composition characterized in that it contains 30% by weight.

Examples of the polyhydroxy resin in the present invention include hydroxyl group-containing polyester, polyether, epoxy resin, acrylic resin, and alkyd resin. In the present invention, using a polybasic acid and a polyhydric alcohol, and optionally a hydroxycarphonic acid, a fatty acid, and an oil or fat, the hydroxyl group is equivalently excess to the carboxyl group at a ratio of 150'C; It is particularly preferable to use polyester resins and alkyd resins obtained by dehydration condensation reaction at a temperature of 250°C.

The amine resin referred to in the present invention is a resin synthesized from formaldehyde and at least one of melamine, urea, benzoguanamine, glycoluril, etc., and is a resin synthesized from formaldehyde and methanol, ethanol, furopanol, impropatol, butanonovaisobutanol, etc. One in which part or all of the methylol group is alkyl etherified with a lower alcohol is used.

In addition, the blocked isocyanate referred to in the present invention is obtained by reacting a polyvalent incyanate such as a polyvalent incyanate, a polymer of a polyvalent isocyanate, an adduct of a polyvalent isocyanate and a polyhydric alcohol with a blocking agent described below, and The one obtained by eliminating the active isocyanate group is used.

Examples of the polyvalent isocyanate include aromatic compounds such as tolylene diisocyanate, metaphenylene diisocyanate, naphthylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, dicyclohexylmethane diisocyanate, and trimethylpentane diisocyanate. , aliphatic group or alicyclic polyvalent isocyanates.

Examples of blocking agents include lactams such as ε-caprolactam and pyrrolidone, secondary or tertiary monoalcohols, oximes such as methyl ethyl ketoxime, and keto alcohols such as acetylacetone.

The amino resin and blocked isocyanate used in the present invention are both curing agent components that undergo a crosslinking reaction with the hydroxyl groups in the polyhydroxy resin during baking of the paint to form a coating film.

In the present invention, the solid content weight ratio of the polyhydroxy resin and the amino resin in the coating composition is preferably 10 to 50 parts by weight of the latter to 100 parts by weight of the former. If this proportion is less than 10 parts by weight, the crosslinking density of the cured coating film will not be sufficient, resulting in insufficient chipping resistance.

Moreover, if it exceeds 50 parts by weight, the cured coating film becomes very hard, and the interlayer adhesion with the top coating film or intermediate coating film is poor (unsuitable for practical use).

In addition, the blending ratio of the polyhydroxy resin and the blocked isocyanate in the coating composition is such that the hydroxyl groups contained in the polyhydroxy resin and the incyanate groups masked by the blocking agent in the blocked isocyanate are equivalent to 1 equivalent of the former. , the latter is preferably 0.5 to 2.0 equivalents. At this equivalent ratio, the block isocyanate is 0.
．． If the amount is less than 5 equivalents, the crosslinking density of the cured coating film will not be sufficient, resulting in insufficient chipping resistance, and if the amount is more than 2.0 equivalents, the cured coating film will become very hard and may be difficult to bond with the top coat or intermediate coat. It has poor interlayer adhesion and cannot be put to practical use.

Next, the terpene or its derivative referred to in the present invention is as follows:
Monocyclic terpenes and dimers thereof such as menthane, limonene, dipentene, tervirune, silvestone, and ferasodrene, bicyclic terpenes such as carane, carene, pinene, camphene, diene, and zabinene, or derivatives having an alcohol or ketone group in the terpene. are exemplified, and one or more of these can be used. It is also possible to use mixtures containing terpenes as a main component, such as turpentine oil and A'H+7 oil.

Terpene or a derivative thereof is an essential component to be blended in order to form a thick coating film by applying and baking the coating composition of the present invention without causing wrinkles. The terpene or its derivative is present in the coating composition of the present invention.
The amount should preferably be 2 to 25%. If the weight ratio is less than 1 weight ratio, forming a coating film with a high film thickness will cause noticeable wrinkles, while if the weight ratio is 30 weight ratio or more, the hardness of the coating film will be insufficient and the chipping resistance will deteriorate.

The anti-chip coating composition of the present invention contains, in addition to a polyhydroxy resin, an amine resin, a blocked isocyanate, a terpene, or a derivative thereof, various materials commonly used in coatings, such as coloring materials such as titanium oxide,
Carbon black, red iron oxide, etc., and extender pigments such as clay, calcium carbonate, barium sulfate, talc, alumina, silica, silica powder, etc. can be mixed and used.

In addition, cellulose derivatives, petroleum resins, phenolic resins, ketone resins, synthetic rubbers, unsaturated polyester resins, natural resins such as rosin, or synthetic resins, leveling agents, anti-sagging agents, antifoaming agents, surfactants, curing accelerators, etc. It is also possible to use various auxiliary agents such as agents.

The chipping-resistant coating composition of the present invention can be prepared by a method known per se. For example, each of the components listed in - is mixed with an organic solvent using a steel mill, a pebble mill, an attriter, a Zandominope blade old high-speed stirrer, etc. It can be adjusted by charging it into a mixing and dispersing machine such as the above and uniformly mixing and dispersing it. Examples of organic solvents used in this case include hydrocarbons such as xylene and solvent naphtha;
Methyl alcohol, 11-butyl alcohol, isobutyl alcohol natonoalcohols, methyl isobutyl ketone, ketones such as cyclohexanone, ethyl acetate, phthyl acetate, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, etc. An example is one in which ordinary paints X1 such as esters and ethers are used as acids. The thus prepared chipping-resistant coating composition is used by applying it to insect bodies such as automobiles.

The coating composition for rigid chipping of the present invention can be applied using an air spray coating machine, an airless spray coating machine, a hot airless spray coating machine, or the like. In addition, after painting and setting the above paint composition,
It is also possible to form a paint film by baking with 'C for 15 to 30 minutes, and it is also possible to apply a normal intermediate coat, top coat, etc. on top of this and bake to form a paint film. - After applying and setting the above coating composition, it is also possible to further apply a conventional intermediate coat and top coat and bake to form a coating film.

According to the present invention, the coating film thickness of the chipping coating composition is usually 70 to 500 μm. If the film thickness is less than 70 μm, the chipping resistance is insufficient and it is not practical, whereas if it exceeds 500 μm, the chipping resistance effect corresponding to an increase in film thickness cannot be expected and is economically disadvantageous. Become.

Therefore, it is practical from the viewpoint of chipping resistance and economy.
A film thickness of ~300μ is preferred.

The chipping-resistant coating composition of the present invention has a good appearance without forming wrinkles even when a high-thickness coating is formed in one application and baking, and has sufficient chipping resistance for practical use. It is something that expresses.

Next, the present invention will be specifically explained with reference to Examples.

In addition, "part" in the examples and comparative examples is a heavy part, and "
% by weight.

Example 1 332 parts of isophthalic acid and 292 parts of adipic acid were placed in a fourth flask equipped with a stirrer, thermometer, nitrogen gas introduction tube, and dehydration tube.
1 part, 45 parts of trimethylolpropane, and 416 parts of neopentyl glycol were placed in a flask and heated to dissolve.
While stirring at a temperature of 0'C to 220C and removing generated water, when the acid value reaches 10, the reaction is terminated and the mixture is cooled. After cooling, 330 parts of butyl cellosolve, 330 parts of Kijiroru
1 part to obtain polyhydroxy resin-A. The hydroxyl group content in the polyhydrogine resin is 10
0.8 per 00 parts, the acid value is 6 and the solid content is 6.
It was 0φ.

Using this resin, apply the following coating for rigid chipping.
A composition was produced.

Polyhydroxy resin-8 (solid content 60%) 70 parts Silica white 100 parts Calcium carbonate 20 parts Dipentene
5th part Gishiroru
Part 30 H A cationic electrodeposition paint was electrodeposited on a copper plate which had been chemically treated with the chipping-resistant paint composition, and then cured by baking.
Coating was carried out so that the thickness varied continuously from μ to 500μ. After setting for 5 minutes at room temperature, an intermediate paint made of melamine alkyd resin was applied with air spray to a dry film thickness of 30 μm, and baked at 140° C. for 20 minutes. Next, a white top coat made of melamine alkyd resin was applied by air spray so that the dried coating film had a thickness of 30 μm, and the sides were baked at 140° C. for 20 minutes to obtain a test plate. The 5.r value of the coating film was tested on the test plate prepared in (1) above, and the results are shown in Table 1.

Example 2 A chipping-resistant coating composition was obtained in the same manner as in Example 1, except that 10 parts of limonene dimer was used instead of 5 parts of dipentene, and a coating film was prepared in the same manner as in Example 1. A test plate was obtained, and the coating film was evaluated.

Example 3 A chipping-resistant coating composition was obtained in the same manner as in Example 1, except that 1 part of gum turpentine was used instead of 5 parts of dipentene, and a coating film was formed using this in the same manner as in Example 1, and tested. A plate was obtained and the coating film was evaluated.

Example 4 Polypropylene glycol 1 with a molecular weight of 1050 was placed in four 1-J flasks equipped with a stirrer, a thermometer, and a nitrogen gas inlet tube.
050 parts of 2.4-tolylene diisocyanate and 348 parts of 2.4-tolylene diisocyanate were reacted for 3 hours at 80°G in a nitrogen stream, then 99 parts of ε-caprolactam was added to block the remaining in/anate groups, and 1497 parts of toluene was added. was added, and blocked isocyanate A was added. This had a solid content of 50 parts and a blocked isocyanate group of 2.8 parts at the end.

A chipping-resistant paint was obtained in the same manner as in Example 1, except that 70 parts of blocked isocyanate A was used instead of 16 parts of amine resin Kneepan 208E-60=q. Using this, a coating film was formed in the same manner as in Example 1. A test plate was obtained, and the coating film was evaluated.

Comparative Example 1 Same as Example 1 except that 5 parts of dipentene was not used,
A chipping-resistant coating composition was obtained and used in Example 1.
A coating film was formed in the same manner as above, a test plate was obtained, and a coating film evaluation (11
I did n.

Comparative Example 2 A chipping-resistant coating composition was obtained in the same manner as in Example 1 except that 15 parts of dipentene was used instead of 5 parts of dipentene.
Using this, a coating film was formed in the same manner as in Example 1 to obtain a test plate, and the coating film was evaluated.

Table 1 [Note] In the table, the content of X1o terpenes is expressed as the ratio of the weight of the terpenes to the weight of the solid content of the polyhydroxy resin.

, *2. ．． The chipping test and adhesion test were conducted at a location where the dry film thickness of the chipping-resistant coating composition was 200 μm.

However, each test method was performed as follows.

Chipping resistance: 10 kg of crushed sand with an average particle size of 3 mm
m and dropped onto each test plate to determine whether the scratches in the coating film reached the metal surface and exposed the metal surface.

Adhesion test: 10 cuts were made vertically and horizontally at intervals of 2 mm until they reached the metal surface using a knife, and cellophane tape was applied to the cut portions and then peeled off to check for 1ζlj separation of the coating film.

Waki test: The maximum film thickness without wrinkling was visually determined within the range of dry film thickness of the chipping-resistant paint composition from 30 μm to 500 tt.

Patent applicant Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] 1. A chipping-resistant coating composition comprising a polyhydroxy resin and an amino resin or a blocked isocyanate, and containing a terpene or a derivative thereof in an amount of 1 to 30% by weight based on the solid content of the polyhydroxy resin.