JPH04227977A - Coating composition - Google Patents

Abstract

PURPOSE:To obtain a coating composition excellent in weathering resistance, scratch resistance, polishability, flexibility and impact strength at low temperatures, and staining resistance by using a specified vinyl copolymer. CONSTITUTION:This composition contains a vinyl copolymer comprising 5-50wt.% vinyl polymer units having a 6-12C cycloaliphatic structure (e.g. cyclohexyl methacrylate, dodecyl methacrylate or n-butyl methacrylate copolymer units) and 5-50wt.% polymer units of the formula (wherein R1 and R2 are each H or CH3; and (n) is 1-5) and having a glass transition temperature of -10 to 30 deg.C.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a coating composition containing a specific vinyl copolymer, and more particularly, to a coating composition containing a specific vinyl copolymer, and more specifically, to improve flexibility, impact resistance, and scratch resistance at low temperatures without impairing weather resistance. The present invention relates to a coating composition that provides a coating film with good stain resistance, polishability (high gloss retention of the coating film after polishing with sandpaper and compound used for repairing the coating film), etc.

0002

BACKGROUND OF THE INVENTION Vinyl resins, particularly acrylic resins, have traditionally been used in applications requiring weather resistance, such as top coatings for automobiles. In recent years, quality requirements for paint films have become even more sophisticated, with automotive exterior paints requiring improved scratch resistance and polishability in addition to weather resistance, and automotive parts made from plastic materials requiring improvements in addition to weather resistance. To,
Improvements in flexibility, impact resistance, scratch resistance, stain resistance, polishability, etc. at low temperatures are desired.

[0003] Conventional techniques for improving scratch resistance include increasing the hardness of the coating by using acrylic resins with a high glass transition temperature or by extremely increasing the crosslinking density such as silicone hard coats. method is adopted. In addition, paints for automobile parts made of plastic materials have a soft composition to improve flexibility and impact resistance at low temperatures, but as this reduces stain resistance and polishability, more than a certain amount of styrene is used. It is customary for the composition to be soft.

0004

[Problems to be Solved by the Invention] However, a coating film with improved scratch resistance by increasing coating hardness has problems such as poor impact resistance because it is hard and brittle, and poor polishability because it is too hard. be.

[0005] Furthermore, paints with increased styrene content and improved stain resistance and polishability as paint resin components used in paints for automobile plastic parts have the problem of reduced weather resistance.

[0006] Accordingly, an object of the present invention is to provide a coating composition that provides a coating film having excellent scratch resistance, polishability, flexibility at low temperatures, impact resistance, and stain resistance without impairing weather resistance. It's about doing.

[0007]

[Means for Solving the Problems] According to the present invention, a vinyl polymer unit having an aliphatic cyclic structure having 6 to 12 carbon atoms (
(hereinafter referred to as polymerized unit A) 5 to 50% by weight, and a polymerized unit represented by the following general formula 2 (wherein R1 and R2 represent a hydrogen atom or a methyl group, and n represents a natural number from 1 to 5) (hereinafter referred to as polymerized unit B) in an amount of 5 to 50% by weight, and a vinyl copolymer having a glass transition temperature of -10 to 30°C.

[0008]

[Case 2]

The present invention will be explained in more detail below.

[0010] The coating composition of the present invention has as a resin component:
It is characterized by containing a specific vinyl copolymer.

The vinyl copolymer used in the present invention has as essential constituent units a vinyl polymer unit having an aliphatic cyclic structure having 6 to 12 carbon atoms, that is, the polymer unit A, and the above general formula 2. It contains the following polymerized unit B. Examples of the vinyl monomer constituting the polymerized unit A include tetracyclododecane acrylate, tetracyclododecane methacrylate, isobornyl acrylate,
Preferred examples include isobornyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, t-butylcyclohexyl acrylate, t-butylcyclohexyl methacrylate, and 2-acryloyloxyethylhexahydrophthalic acid. Examples of vinyl monomers constituting the polymerized unit B include reaction products of caprolactone with 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, etc. " (manufactured by Daicel Chemical Industries, Ltd.) and the like can be preferably mentioned.

In the present invention, the proportion of each polymerized unit contained in the entire vinyl copolymer is such that the polymerized unit A is 5 to 50% by weight, and the polymerized unit B is 5 to 50% by weight.
-50% by weight. At this time, the polymerization unit A is 5
If styrene is less than % by weight, unless a large amount of styrene is used, flexibility and impact resistance at low temperatures, scratch resistance, stain resistance, and polishability will not be satisfied, and weather resistance will deteriorate. Moreover, when it exceeds 50% by weight, flexibility decreases and flexibility at low temperatures decreases. Furthermore, when the polymerized unit B is less than 5% by weight,
The soft portion introduced by the polymerized units B decreases, making the material hard and brittle, resulting in insufficient scratch resistance, low-temperature flexibility, and impact resistance. Moreover, if it exceeds 50% by weight, it becomes too soft and cannot provide scratch resistance, stain resistance, and polishability, so it is necessary to adjust the content to the above-mentioned content ratios. That is, in the coating composition of the present invention, since the polymerized unit A and the polymerized unit B are used as the polymerized units constituting the vinyl copolymer contained as the resin component, even if the styrene content is reduced, the vinyl copolymer Flexibility can be imparted to the system polymer, thus improving photostability, and improving the weather resistance, flexibility and impact resistance at low temperatures, scratch resistance, stain resistance, and polishability of coating compositions. can be done.

The vinyl copolymer used in the present invention is
In addition to the polymerization unit A and the polymerization unit B, other vinyl polymerization units may be included. Examples of monomers constituting the other vinyl polymer units include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, octyl acrylate, octyl methacrylate, dodecyl acrylate, dodecyl methacrylate, octadecyl acrylate, and octadecyl methacrylate. Acrylic monomers with no functional group other than unsaturated double bonds such as; Acrylic monomers with carboxyl groups such as acrylic acid and methacrylic acid; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, Acrylic monomers containing hydroxyl groups such as hydroxypropyl acrylate and hydroxypropyl methacrylate; Acrylic monomers containing epoxy groups such as glycidyl acrylate and glycidyl methacrylate; Esters of maleic acid and monohydric alcohol; Styrene, α- Other vinyl monomers such as methylstyrene, vinyl acetate, vinyl chloride, etc. can be preferably used.

The vinyl copolymer used in the present invention has the above-mentioned essential polymerization units, and further has a glass transition temperature of -10 to
It is necessary to keep the temperature within the range of 30°C. The glass transition temperature is -
If the temperature is less than 10°C, the polishability will be poor, and if it exceeds 30°C, the flexibility and impact resistance at low temperatures will be poor, which is not preferable.

The vinyl copolymer used in the present invention can be produced by a solution polymerization method by dissolving each of the above-mentioned vinyl monomers in an organic solvent and heating the solution in the presence of a radical polymerization initiator to cause a polymerization reaction. can. Examples of organic solvents include toluene, xylene, and the trade name "Solvesso #1".
Aromatic hydrocarbon solvents such as "00" (manufactured by Exxon Chemical Co., Ltd.); ester solvents such as ethyl acetate, butyl acetate, ethylene glycol monoethyl acetate, propylene glycol monomethyl ether acetate; methyl isobutyl ketone, methyl amyl ketone Ketone solvents such as;
Alcohol solvents such as butyl alcohol and amyl alcohol; ether alcohol solvents such as ethylene glycol monobutyl ether can be used; and as radical polymerization initiators, benzoyl peroxide, lauroyl peroxide, t-butyl peroxybenzoate, azobisisobutyl Ronitrile etc. can be used.

The vinyl copolymer contained in the coating composition of the present invention preferably has a number average molecular weight of 1,000 to 50,000. If the number average molecular weight is less than 1,000, the weather resistance, water resistance, flexibility and impact resistance at low temperatures, scratch resistance, stain resistance, etc. of the coating film will be poor, and if it exceeds 50,000, the coating will be poor. This is not preferable because it impairs workability.

In the coating composition of the present invention, a crosslinking agent may be added in an amount of 5 to 70 parts by weight, preferably 20 to 50 parts by weight, based on 100 parts by weight of the vinyl copolymer. If the amount of the crosslinking agent exceeds 70 parts by weight, the weather resistance and water resistance of the coating film will deteriorate, which is not preferable. As the crosslinking agent used in the present invention, for example, polyisocyanate, amino resin, etc. can be suitably used. Specifically, as the polyisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,
4-(or 2,6-) diisocyanate, 4,4-methylenebis(cyclohexyl isocyanate), and adducts of these diisocyanates with polyhydric alcohols such as ethylene glycol and trimethylolpropane;
Alternatively, examples thereof include a buret body added with water, a polymer of these diisocyanates, and further a blocked isocyanate compound obtained by blocking each of the above polyisocyanate compounds with a lower monohydric alcohol, ε-caprolactam, or the like. Further, examples of the amino resin include those obtained by adding formaldehyde to melamine, benzoguanamine, etc., and then etherifying it with a monohydric alcohol having 1 to 4 carbon atoms. These amino resins may be used as a mixture of two or more.

[0018] Solvents, pigments and additives can be added to the coating composition of the present invention, if necessary. Further, other resins such as acrylic resins having compatibility may be added within a range that does not adversely affect the effects of the present invention.

The coating composition of the present invention can be applied to metals, synthetic resins,
Can be painted on various materials such as wood, glass, concrete, etc.
It can be used for a variety of purposes, including automobiles, home appliances, building materials, and pre-coating metals.

[0020]

Effects of the Invention The coating composition of the present invention has excellent flexibility and impact resistance at low temperatures without impairing its weather resistance.
It has scratch resistance, stain resistance, and polishability, and can be used for a variety of painting applications.

[0021]

[Example] Next, according to synthesis examples, working examples, and comparative examples,
The present invention will be specifically explained. All parts and percentages hereinafter are based on weight unless otherwise specified.

[0022]

[Synthesis Example 1] A flask equipped with a stirrer, a reflux condenser, and a thermometer was charged with 80.0 parts of xylene based on the formulation of Synthesis Example 1 in Table 1, and the temperature was raised to 140°C. Next, based on the formulation shown in Table 1, monomers and polymerization initiators were added dropwise at 140°C over 3 hours. Then, 0.5 part of t-butyl peroxybenzoate was added, and 140 parts of t-butyl peroxybenzoate was added.
The reaction was continued at ℃ for 2 hours, and the heating residue shown in Table 1 was 56.3%.
, a resin solution having a number average molecular weight of 6,900 was obtained.

[0023]

[Synthesis Examples 2 to 13] The reaction was carried out using the same reaction apparatus as in Synthesis Example 1 and following the same reaction procedure as in Synthesis Example 1, except for using the solvent, monomer and polymerization initiator shown in the blending ratios in Tables 1 and 2. I let it happen. The properties of the obtained varnish are shown in Tables 1 and 2.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Examples 1 to 9, Comparative Examples 1 to 4] Using the resin solutions obtained in each of the above synthesis examples, paints were obtained using the compounding ratios shown in Table 3 according to a conventional coating method. The obtained paint was applied to a commercially available polypropylene plate coated with the product name "Primac No. 1500 Primer" (manufactured by Nippon Oil & Fats Co., Ltd.) to a dry film thickness of approximately 30 μm.
It was coated to a thickness of .mu.m and baked at 80.degree. C. for 30 minutes. Next, a performance test was conducted for each item shown in the same table. The results are summarized in Table 3.

[0027]

[Table 3]

[0028]

[Examples 10 to 18, Comparative Examples 5 to 8] Using the resin solutions obtained in each of the above synthesis examples, paints were obtained using the blending ratios shown in Table 4 according to a conventional coating method. Next, zinc phosphate treatment (trade name: “Bonderite #3004”)
”, manufactured by Nippon Parkerizing Co., Ltd.) on a copper plate coated with cationic electrodeposition paint (trade name: “Aqua #4100”).
Nippon Oil & Fats Co., Ltd.) was applied to a dry film thickness of 20 μm and baked at 175°C for 30 minutes. Co., Ltd.) to a dry film thickness of 30 μm and baked at 140° C. for 30 minutes to prepare a test plate. The obtained test plate was spray-coated with the previously prepared paint to a dry film thickness of about 30 μm, and baked at 140° C. for 30 minutes to prepare a test piece. Next, a performance test was conducted on the obtained test piece. However, for the weather resistance test, test pieces using the trade name "Hi Epico No 1 White" as the intermediate coating were used, and for other tests, test pieces using the trade name "Hi Epico No 1 Black" as the intermediate coating were used. . The results are shown in Table 4.

[0029]

[Table 4]

[0030] Each test was conducted by the method shown below. 1) Glossiness JIS K 5400, 6.7 60
By specular gloss meter. 2) Stain resistance test piece is sanded with #1500 abrasive paper and then rubbed with carbon black. Next, the condition after wiping off the dirt with white gasoline was evaluated. ○ No stains remain. × Black stains remain. 3) Weather resistance JIS D 0205, 7.6 accelerated weather resistance test method Sunshine Weather Meter, 1
Judgment was made based on the color difference (ΔE) after 000 hours. ○
△E is less than 2.0 x △E is 2.0 or more 4) Polishability After sanding the test piece with #1500 abrasive paper, a compound (FMC831P, trade name
Waxing was performed using Ishihara Pharmaceutical Co., Ltd.) and the degree of gloss recovery was evaluated. ○ The gloss recovery rate of the coating film is 90% or more × The gloss recovery rate of the coating film is less than 90% 5) Flexibility and impact test at low temperature After leaving the specimen in a refrigerator at 20 ° C for 2 hours or more, the back side Bend the specimen by applying it to a 1 inch diameter mandrel. The state of the coating film at that time was evaluated as follows. ○ No abnormalities × Cracks occur in the paint film. Under the same conditions as above, JIS K
5400, 6.13.3B method (impact deformation test),
A test piece is sandwiched upward between a shooting die with a radius of 6.35 mm and a cradle, and a weight having a mass of 500 g is dropped from a specified height to evaluate damage to the paint film. ○ No damage to the paint film × Damage to the paint film 6) Spot 1 ml of gasoline-resistant gasoline (trade name, "Nisseki Silver Gasoline", manufactured by Nippon Oil Co., Ltd.) on the test piece. After drying for 20 seconds, spot again. After repeating this 10 times, the surface condition of the test piece was evaluated. ○ Abnormalities such as stains and blisters are not observed × Stains and blisters are observed 7) Fix the scratch resistance test piece to the roof of a passenger car and check the condition of the paint film after running it through a car wash 20 times. evaluated. ○ There are no scratches at all, or there are a few scratches, but they are not noticeable. ×
Scratches are noticeable. As is clear from the results in Table 3, when applied to plastic materials, the coating compositions of the present invention (Examples 1 to 9) have excellent gloss, stain resistance, weather resistance,
Shows polishability, flexibility at low temperatures, and impact resistance. However, in Comparative Example 1, the vinyl polymer contained more than 50% by weight and 60% by weight of polymerized unit B (Plaxel FM2 (trade name, manufactured by Daicel Chemical Industries, Ltd.)), which is a soft component. The coating film becomes too soft, resulting in poor stain resistance and polishability. In Comparative Example 2, the vinyl copolymer does not have the polymerized unit A and a large amount of styrene is used, resulting in poor weather resistance. In Comparative Example 3, the vinyl copolymer does not have the polymerized unit A and contains a large amount of methyl methacrylate, which is a chain hard component, and therefore has poor flexibility and impact resistance at low temperatures. In Comparative Example 4, since the vinyl copolymer does not contain polymerized unit B, which is a soft component, the coating film becomes too hard and has poor flexibility and impact resistance at low temperatures.

Furthermore, as is clear from the results shown in Table 4, when the coating composition of the present invention (Examples 10 to 10) was applied to a copper plate,
No. 18) exhibits excellent gloss, gasoline resistance, weather resistance, polishing property, and scratch resistance. However, in Comparative Example 5, since the vinyl polymer contained more than 50% by weight of the polymerized unit B, which is a soft component, and 60% by weight, the coating film became too soft, resulting in poor gasoline resistance and polishing properties. inferior in sex. In Comparative Example 6, the vinyl copolymer does not have polymerized unit A and a large amount of styrene is used, resulting in poor weather resistance. Comparative Example 7 does not contain polymerized unit A, and therefore has poor polishability and scratch resistance. In Comparative Example 8, the vinyl copolymer did not contain the polymerized unit B, which is a soft component, so the coating film was too hard and had poor scratch resistance.

Claims (2)

[Claims] Claim 1: 5 to 50% by weight of vinyl polymer units having an aliphatic cyclic structure having 6 to 12 carbon atoms, and the following general formula 1 (wherein R1 and R2 represent a hydrogen atom or a methyl group, n represents a natural number from 1 to 5)
50% by weight of a vinyl copolymer having a glass transition temperature of -10 to 30°C. [Chemical formula 1] 2. The coating composition according to claim 1, which contains 5 to 70 parts by weight of a crosslinking agent based on 100 parts by weight of the vinyl copolymer.