JPS6216147B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to improving the surface properties of acrylic urethane resin paint coatings, such as increasing the surface hardness and preventing scratches. Acrylic modified urethane resin paints have good adhesion to various substrates and relatively high film hardness, and also have excellent weather resistance, water resistance, and chemical resistance, and are suitable for use on plastic molded products, metals, glass, ceramics, etc. Widely used for ceramics, wood, etc. However, although the surface hardness and chemical resistance of acrylic urethane resin paint films can be improved to some extent by increasing the crosslinking density or by combining them with epoxy resins, etc., they are inherently susceptible to scratches with a pencil hardness of HB to F and can last a long time. During use for a period of time, if dust or hard substances come into contact with the paint, or if these adhere to it and rub it with cloth or paper, the paint film will be damaged and the purpose of painting to enhance its beauty will be lost. In particular, acrylic urethane resin paints used for painting plastic molded products must be made to follow the deformation and distortion of the base material, otherwise the paint film will crack and have poor adhesion, so it is necessary to slightly lower the hardness and increase the flexibility. Because of this, it is even more vulnerable. Methods used to increase the hardness of acrylic urethane resin paint films include increasing the baking temperature and using acrylic polyols with a high glass transition point Tg or high acid value, but the hardness is at most pencil hard. It is about 2H, which is not practically satisfactory, and
It is not preferable because it tends to cause cracks and pinholes in the coating film and has poor weather resistance. The purpose of the present invention is to further improve the hardness, weather resistance, water resistance, and chemical resistance of the painted surface of the current acrylic urethane resin paint, and to further improve the adhesion, appearance, color, etc. of the painted surface of the acrylic urethane resin paint. figure,
The purpose is to provide a method for protecting painted surfaces. Therefore, the object of the present invention can only be achieved by specifying and combining an undercoat (acrylic urethane resin paint) and a top coat. It does not get damaged easily even when rubbed with something, and can maintain its original adhesion, gloss, and beauty even when left outdoors for long periods of time under harsh conditions. That is, the present invention is directed to resins mainly composed of methyl methacrylate, polycarbonate resins, ABS
Contains less than 50% by weight of methyl methacrylate, has a hydroxyl value of 10 to 200, and has an acid value of 1.
~12 acrylic polyols and a non-yellowing polyisocyanate with an OH/NCO equivalent ratio of 0.6 to 1.2
This is a surface protection method for a painted surface, which is characterized in that after applying an acrylic urethane resin paint as an undercoat, a topcoat mainly consisting of hydrolysis with a tetraalkoxysilane and an alkyltrialkoxysilane is applied. The present invention will be explained in more detail below. In the present invention, the acrylic urethane resin paint refers to a paint consisting of an acrylic polyol and a non-yellowing polyisocyanate as main components. Acrylic polyol has a hydroxyl value (OH value) of 10~
200, and preferably has an acid value of 1 to 12. Within this range, a coating film with good adhesion to metals, plastics, etc. and excellent weather resistance can be obtained. If the OH value is less than 10, the solvent resistance of the coating film will be poor, while if the OH number is greater than 200, cracks will easily occur in the coating film. If the acid value is less than 1, adhesion will be poor and yellowing will occur easily due to heat, while if the acid value is more than 12, the coating will tend to crack and the weather resistance will be poor, which is not preferred. Acrylic polyol components include unsaturated carboxylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; (meth)acrylic acid, crotonic acid, itaconic acid, and fumaric acid. Carboxylic acids with 〓C=C〓 bonds such as acids; 〓C=C〓 bonds such as glycidyl (meth)acrylate and

[Formula] Compound having a bond; (meth)acrylamide, etc.
Compound with C=C〓 bond and -CONH ₂ ; unsaturated polyester having hydroxyl groups at both ends of the molecule, at least one other such as styrene, methylstyrene, vinyltoluene, 2-hydroxyethyl (meth)acrylate, 2- Copolymers with (meth)acrylates having hydroxyl groups such as hydroxypropyl (meth)acrylate, ethylene glycol mono(meth)acrylate, and trimethylolpropane triacrylate can be typically used. The proportion of methyl methacrylate in the polymer component of the acrylic urethane resin paint is preferably less than 50% by weight; if it exceeds 50% by weight, the coating film becomes highly flexible and easily cracks, resulting in poor weather resistance and durability. It has poor heat cycle properties and is not preferred. Further, as the non-yellowing polyisocyanate component, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, xylene diisocyanate, etc. can be typically used. The equivalent ratio of OH groups in acrylic polyol to NCO groups in polyisocyanate (OH/NCO) is
0.6 to 1.2 is appropriate. Crosslinking progresses within this range,
A coating film with excellent adhesion, weather resistance, moisture resistance, water resistance, etc. can be obtained. The acrylic urethane resin paint used in the present invention also consists of solvent components such as xylol and butyl acetate, and various additives, and if necessary, cellulose derivatives, epoxy resins, polyester resins, amino resins, etc. are mixed as modifiers. I can do that. Acrylic urethane resin paint is adjusted to the appropriate viscosity with thinner and applied by normal brush painting, spray painting, dip painting, curtain flow coater roll painting, etc., and is heated at room temperature or about 50 to 80 degrees Celsius.
Can be force-dried. Although the dry film thickness is not particularly limited, it is usually about 1 to 50 microns. It has been found that even if such an abnormality in appearance is not observed, there is a disadvantage that chemical resistance and abrasion resistance tend to be poor. The present inventors placed more emphasis on the hot water resistance, heat cycle resistance, and weather resistance of the coating film, and in order to improve these properties, we developed a partial hydrolyzate of tetraalkoxy silicon in the silicon component and a partial hydrolyzate of an organosilicon compound. As a result of various studies regarding the ratio of decomposed products, the present invention, which will be described in detail below, was arrived at. That is, the present invention is based on (A) the general formula R _o Si (OR') _4-o (where n is an integer of 1 to 3, R is a hydrocarbon group having 1 to 6 carbon atoms, and R' is a group having 1 to 6 carbon atoms). R _o SiO〓〓〓 (in the formula, n
Tetraalkoxysilicon partial hydrolyzate calculated as SiO ₂ based on 100 parts by weight of the partial hydrolyzate of the above general formula R _o Si (OR') _4-o , and R as defined above) A silicon compound partial hydrolyzate containing 5 to 100 parts by weight of decomposition product, and R in (B) and (A)
General formula calculated as _o SiO〓〓〓 _o Si(OR′) _4-o
For 100 parts by weight of a partial hydrolyzate of the compound represented by (hereinafter abbreviated as acrylic copolymer) and 0 to 150 parts by weight of etherified methylolmelamine are dissolved in a solvent. This is a coating composition obtained by That is, in the composition of the present invention, as a silicon component, the ratio of a partial hydrolyzate of an organosilicon compound to a partial hydrolyzate of tetraalkoxy silicon is increased to improve the hot water resistance, heat cycle resistance, and weather resistance of the coating film. On the other hand, the ratio is set within a range that provides the practical abrasion resistance of the coating film, and therefore the flexibility, which is insufficient with just the silicon component, is improved by adding an acrylic copolymer and etherified methylolmelamine. be. Furthermore, since the composition of the present invention uses an acrylic copolymer, it has particularly good adhesion to acrylic substrates, and has good adhesion to molded articles made of methyl methacrylate homopolymer or copolymer. A coating film with good adhesion can be obtained without any pretreatment. Furthermore, the addition of etherified methylolmelamine is often particularly effective in providing the coating with both hardness and flexibility. The tetraalkoxy silicon used in the present invention is one in which the alkoxy group is methoxy, ethoxy, propoxy, butoxy, or the like. Also, the general formula R _o Si
(OR′) In the organosilicon compound represented by _4-o ,
Specifically, the hydrocarbon group R having 1 to 6 carbon atoms is an organic group such as methyl, ethyl, propyl, butyl, pentyl, hexyl, vinyl, allyl, phenyl, etc., and the alkyl group R′ having 1 to 4 carbon atoms. means methyl group, ethyl group, propyl group, butyl group, etc. Partially hydrolyzed products of these silicon compounds are prepared by combining tetraalkoxy silicon and the organosilicon compound of the general formula R _o Si (OR') _4-o, separately or in combination, in a mixed solvent such as water and alcohol, for example, with an acid. obtained by hydrolysis in the presence of In some cases, these partial hydrolysates of silicon compounds can also be obtained by directly hydrolyzing silicon chlorides such as SiCl ₄ and R _o SiCl _4-o .
Generally, it is often better to mix these silicon compounds and co-hydrolyze them simultaneously than to hydrolyze them separately. In particular, the general formula R _o Si
In the case of a compound in which n=2 or n=3 in (OR') _4-o , it is preferable to perform cohydrolysis after mixing with tetraalkoxy silicon. The ratio of the tetraalkoxysilicon partial hydrolyzate thus obtained to the partial hydrolyzate of the organosilicon compound of R _o Si (OR') _4-o is calculated as _{R o} SiO〓〓 (OR') It is preferable that at least one partial hydrolyzate of the _4-o organosilicon compound is 5 to 100 parts by weight of a tetraalkoxysilicon partial hydrolyzate calculated as SiO ₂ per 100 parts by weight. . If the content of the tetraalkoxy silicon partial hydrolyzate is less than 5 parts by weight, the hardness of the coating film will decrease and practical abrasion resistance will be lost; if it is more than 100 parts by weight, the coating film will have poor hot water resistance and heat cycle resistance. , weather resistance tends to deteriorate. Acrylic copolymers used with silicon components include alkyl (meth)acrylates, hydroxyalkyl (meth)acrylates, azobisisobutyronitrile, benzoyl peroxide, di-
It can be obtained by bulk polymerization, emulsion polymerization, suspension polymerization or solution polymerization in the presence of a radical polymerization initiator such as tert-butyl peroxide. As the alkyl (meth)acrylate, (meth)acrylic acid esters of alcohols having 1 to 18 carbon atoms can be selected. Particularly useful are ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and the like. Examples of hydroxyalkyl (meth)acrylates include 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate,
Glycerol mono(meth)acrylate and the like can be used. Alkyl (meth) in acrylic copolymers
There is no particular limit to the composition ratio of acrylate and hydroxyalkyl (meth)acrylate, but the weight ratio is 1/10 or more, considering the adhesion between the final coating film and the base material, the flexibility of the coating film, etc. It is preferably within the range of 10/1. The amount ratio of the acrylic copolymer in the composition of the present invention is calculated as R _o Si O 〓 _〓
(OR′) Partial hydrolyzate of compound represented by _4-o 100
It is desirable that the amount of the acrylic copolymer be in the range of 5 to 200 parts by weight. If the amount of the acrylic copolymer is less than 5 parts by weight, the final coating film will have poor heat cycle resistance and will have a strong tendency to crack. If the amount of the acrylic copolymer exceeds 200 parts by weight, the hardness of the coating film will be impaired and the coating film will tend to whiten when immersed in hot water. The production method of the etherified methylolmelamine used in the composition of the present invention has already been described in many documents, and there are also many commercially available products. Preferred are hexa(alkoxymethyl)melamines, such as hexa(methoxymethyl)melamine, hexa(ethoxymethyl)
Melamine, hexa(propoxymethyl) melamine, hexa(isopropoxymethyl) melamine,
Examples include hexa(butoxymethyl)melamine and hexa(cyclohexyloxymethyl)melamine. The amount ratio of etherified methylolmelamine in the composition of the present invention is calculated as _{R o} SiO 〓 _{〓 〓} 〓 The amount of methylolmelamine chloride is preferably in the range of 0 to 150 parts by weight; if it exceeds this range, the adhesion of the coating film, especially the adhesion in hot water, will be adversely affected. Solvents used in the production of coating compositions include alcohols, ketones, esters, ethers, cellosolves, halides,
Carboxylic acids, aromatic compounds, etc. can be used, but their selection will depend on factors such as the polymer material base used and evaporation rate, and may be mixed in a wide range of proportions with the components of the coating composition. used. In particular, lower alkyl carboxylic acids such as formic acid and acetic acid are effective in increasing the adhesion between the substrate and the coating film. Lower alcohols (e.g. methanol, ethanol, propanol, butanol),
lower alkyl carboxylic acids (e.g. formic acid, acetic acid,
propionic acid), aromatic compounds (e.g. benzene, toluene, xylene) and cellosolves (e.g. methyl cellosolve, butyl cellosolve)
It is particularly useful to use them in combination. The amount of solvent used can be appropriately selected depending on the required thickness of the coating film, coating method, etc. The above composition of the present invention is heated at 70°C after coating on the base material.
A cured coating film can be obtained by baking at a temperature above, but in order to further lower the curing temperature and shorten the curing time, it is necessary to use acids such as hydrochloric acid, toluenesulfonic acid, organic amines, organic carbon It is useful to use curing accelerating catalysts such as acid metal salts, thiocyanate metal salts, nitrite metal salts, organotin compounds, and the like. In addition, when a particularly thick coating is required, yuzu skin,
In order to prevent surface defects such as creases and to prevent paint film from repelling, it is also possible to add a surfactant to the composition of the present invention. Addition of small amounts of polymer produces good coatings. The amount of these curing accelerating catalysts and surfactants added, and in the present invention, the top coat mainly composed of a hydrolyzate of organosiloxane is composed of a tetraalkoxysilane represented by the general formula Si(OR) ₄ and a general formula R'Si.
(OR) It is a hydrolyzate of a mixture consisting of at least one type of alkyltrialkoxysilane represented by ₃ , or a mixture of each hydrolyzate. Here, R and R' are hydrocarbon groups; for example, in tetraalkoxysilane, the alkoxy group is methoxy, ethoxy, propoxy, putoxy, etc., and in alkyltrialkoxysilane, the alkyl group is methyl ,ethyl,
Examples include (iso)propyl, (iso)butyl, pentyl, hexyl, and phenyl, and there are also those with alkoxy groups such as methoxy, ethoxy, propoxy, and butoxy. The composition ratio of tetraalkoxysilane and alkyltrialkoxysilane is preferably in the range of 50 to 400 parts of the latter to 100 parts of the former. For hydrolysis of the silane compound, a solvent such as water, alcohol, acetone, diacetone alcohol, dioxane, etc., and a small amount of acid, if necessary, are used. Furthermore, a small amount of curing accelerator,
Additives such as surface smoothing agents, antistatic agents, wetting agents, ultraviolet absorbers, colorants, etc. can also be added.
In addition, organic polymers such as alkyl (meth)acrylate, /hydroxyalkyl (meth)acrylate copolymers, and etherified methylolmelamine may be added for the purpose of improving the physical properties of the topcoat coating, especially heat cycle resistance. You can also do it.
Further, other organic solvents may be added as long as they do not attack the undercoat or the object to be coated and do not cause clouding or precipitation. Such organic solvents include:
Alcohols, ketones, esters, cellosolves, halides, carboxylic acids, aromatic compounds, etc. can be used. In particular, the use of lower alkyl carboxylic acids such as formic acid and acetic acid improves the adhesion with the undercoat paint and the hot water resistance of the paint film, and is also effective in preventing increases in the viscosity of the liquid after preparing the topcoat paint and preventing gelation. There is. The top coat can be applied in the same way as the base coat, and the drying and curing conditions are usually the same.
It takes 10 minutes to 10 hours at 50 to 140℃, and it depends on the heat resistance of the object to be coated, but generally it takes 1 to 10 minutes at 70 to 100℃.
Conditions of ~2 hours are appropriate. The dry film thickness is not particularly limited, but is preferably 1 to 10 microns. Furthermore, the method of the present invention can be applied to any object to be coated as long as the acrylic urethane resin paint has good adhesion, but in particular, resins mainly containing methyl methacrylate, polycarbonate resins, acrylonitrile-styrene-butadiene copolymers, Acrylonitrile-styrene copolymer, methyl methacrylate-styrene copolymer, and directly on their surfaces, or urethane resin paint, acrylic resin paint, polyester-modified acrylic resin paint, epoxy-modified acrylic resin paint, UV-curable acrylic resin paint Suitable for plastic molded products where a thin metal film is applied as an undercoat, such as metal from, metal aluminum, nickel-chromium alloy, stainless steel, etc., on the surface layer by vacuum evaporation, sputtering, chemical plating, hot stamping, etc. There is. The present invention will be explained below with reference to Examples. still,
"Part" means part by weight. Production example of acrylic polyol Production example 1 50 parts of xylene and 17 parts of butyl acetate were placed in a 300ml four-necked flask equipped with a thermometer, stirrer, condenser, and dropping funnel, and after replacing the inside of the flask with nitrogen, Keep the contents below 30℃ and add 2.5 parts of azobisisobutyronitrile, 65 parts of 2-ethylhexyl acrylate, and 25 parts of hydroxyethyl acrylate.
A monomer mixture consisting of 10 parts of methyl methacrylate and 10 parts of methyl methacrylate was placed in a dropping funnel, and the contents of the flask were
Keep at 112°C and drip for 3 hours. After completion of the dropwise addition, the temperature was kept at this temperature for 1 hour, and then 0.5 parts of azoisobutylvaleronitrile and 10 parts of butyl acetate were added dropwise and the mixture was reacted at 112°C for about 3 hours. After the reaction is complete, cool to 80℃ and remove the solid content with xylene.
70% to obtain an acrylic copolymer solution with a polymerization rate of 100%, a hydroxyl value of 120, and a glass transition point of -43°C. Production Examples 2 to 7 Production Example-1 was prepared using the monomer formulation shown in Table-1.
A solution of an acrylic copolymer was prepared in the same manner as described above.

【table】

[Table] Production example of topcoat paint (organosiloxane hydrolyzate) Production example 8 (1) Preparation of solution of co-partial hydrolyzate of tetraethoxy silicon and methyltriethoxy silicon (components) Hydrolysis vessel equipped with a reflux condenser 68 g of isopropyl alcohol, 38 g of tetraethoxy silicon, and 72 g of methyltriethoxy silicon were mixed and dissolved, and 36 g of a 0.05N aqueous hydrochloric acid solution was added, and the solution was heated under reflux for 5 hours with stirring to perform cohydrolysis. After the reaction, the mixture was cooled to room temperature to obtain a cohydrolyzate. The resulting solution contained 5.1% _of tetraethoxy silicon partial hydrolyzate, calculated as _SiO2 , and _12.6 % of methyltriethoxy silicon partial hydrolyzate, calculated as _CH3SiO1.5 . (2) Synthesis of acrylic copolymer (components) 40 g of butyl acrylate, 10 g of 2-hydroxyethyl methacrylate, and 0.5 g of azobisisobutyronitrile were dissolved in 300 g of ethyl alcohol, and the mixture was heated at 70°C under a nitrogen atmosphere for 50 minutes. Polymerization was carried out by heating and stirring for hours. After the reaction was completed, the contents were poured into petroleum ether to remove unreacted monomers to obtain a copolymer. (3) Preparation of topcoat paint Mix 100 parts of the above ingredients with 10 parts of other ingredients, add 60 parts of n-butanol, 40 parts of acetic acid, and 20 parts of xylene.
0.4 part of sodium acetate and 0.2 part of surfactant NUCY-7006 manufactured by Nippon Unicar Co., Ltd. were added and dissolved to prepare a paint. Examples 1 to 6 and Comparative Example 1 The acrylic copolymer solutions obtained in Production Examples 1 to 7 and polyisocyanate were mixed and dissolved in the formulations shown in Table 2 to obtain acrylic urethane resin paints. The obtained acrylic urethane resin paint for undercoat was mixed with polymethyl methacrylate resin (trade name
Sumipetux B MHO, manufactured by Sumitomo Chemical Co., Ltd.)
150mm×200mm× obtained by injection molding using
Paint a 3mm rectangular molded product to a film thickness of 35 to 45 microns, leave it indoors for about 15 minutes, and then heat it to 80℃.
The sample was force-dried for 1 hour to obtain a test piece. The top coat obtained in Production Example 8 was applied to the obtained test piece by a dipping method so that the coating film thickness after drying was 5 μm, and dried at 80° C. for 2 hours. The obtained coated product was tested according to the test method shown below, and the results are shown in Table 2. a Adhesion...Use a steel knife to make 100 cuts reaching 1 mm square on the paint film, stick cellophane tape (manufactured by Sekisui Chemical) on top of the cuts, and then pull the cellophane tape strongly upward in a 90° direction. Evaluation was made based on the number of squares remaining when peeled off. b. Abrasion resistance...Rubbed with #000 steel wool to examine scratch resistance. The judgment was as follows. A: No scratches B: Some scratches C: Many scratches The polymethyl methacrylate board that was not painted at all was grade C. c Hot water resistance test: The state of the coating film was examined after immersing it in hot water at 80°C and leaving it for 2 hours. d. Heat cycle test: The sample was placed in a hot air dryer at 80°C for 2 hours and then in ice salt water at -20°C for 2 hours. After repeating this process 10 times, the state of the coating film was examined. e Weather resistance... Measure the sample with a sunshine weather meter (WE-SUN-HCA- manufactured by Suga Test Instruments Co., Ltd.)
The state of the coating film was observed after 500 hours of irradiation with Type 1). f Pencil hardness...Tested based on JIS K5400. Comparative Examples 2 to 10 Same as Examples 1 to 7 for test pieces obtained by drying polymethyl methacrylate resin plates coated with acrylic urethane resin paints obtained in the same manner as Examples 1 to 7 under the drying conditions shown in Table 3. Performance tests were conducted. The results are shown in Table 3.

【table】

【table】

[Table] Example 7 An iron plate with a thickness of 0.8 mm that was degreased in the same manner as in Example 5, a polycarbonate resin plate (Polycarbonate, manufactured by Tsutsunaka Plastic Industries Co., Ltd.), an ABS resin molded product (Clarastick MH, manufactured by Sumitomo Naugatatsu Co., Ltd.), An acrylic urethane resin paint was applied to a transparent polystyrene resin molded product (S-Brite #8, manufactured by Sumitomo Chemical Industries, Ltd.), and after forced drying under the drying conditions shown in Table 4, the top coat obtained in Production Example 8 was obtained. Apply and dry. Table 4 shows the performance of the coated products.

[Composition of acrylic urethane resin paint]

Solution of acrylic polyol 100 parts MMA in solid content 60% Hydroxyl value 50 Acid value 3.0 Glass transition point 80°C Nonvolatile content 50wt% Dismodule N-75 15 parts Biuret compound of hexamethylene diisocyanate manufactured by Bayer AG Xylene 50 parts Butyl acetate 40 parts Cellosolve Acetate 10 parts Comparative Example 11 Table 5 also shows the results of a performance test on an ABS vacuum-deposited product similar to Example 8 coated with an acrylic urethane resin paint.

【table】

Claims (1)

[Scope of Claims] 1. An overcoat mainly composed of an organosiloxane hydrolyzate on a surface coated with a paint mainly composed of an acrylic urethane resin containing less than 50% by weight of methyl methacrylate in the resin solid content. A surface protection method for painted surfaces characterized by applying paint. 2. The paint is mainly made of acrylic urethane resin, which is mainly made of acrylic polyol with a hydroxyl value of 10 to 200, acid value of 1 to 12, and non-yellowing polyisocyanate, and has an OH/NCO equivalent ratio of 0.6 to 1.2. A surface protection method for a painted surface according to claim 1, characterized in that: 3. The surface protection method for a painted surface according to claim 1, wherein the top coating is a coating mainly composed of a hydrolyzate of tetraalkoxysilane and alkyltrialkoxysilane. 4 As a top coat (A) General formula R _o Si (OR') _4-o (where n is an integer of 1 to 3, R is a hydrocarbon group having 1 to 6 carbon atoms, R' is a hydrocarbon group having 1 to 6 carbon atoms) R _o SiO〓〓〓 (in the formula, n and R are 5 to 100 parts of a tetraalkoxy silicon partial hydrolyzate calculated as SiO ₂ based on 100 parts by weight of the partial hydrolyzate of the above general formula R _o Si (OR') _4-o calculated as (as defined above) A partial hydrolyzate of a silicon compound containing parts by weight and a partial hydrolyzate of a compound represented by the general formula R _o Si (OR') _4-o calculated as R _o SiO in (B) and (A) Obtained by dissolving 5 to 200 parts by weight of a copolymer of alkyl acrylate or/and alkyl methacrylate and hydroxyalkyl acrylate or/and hydroxyalkyl methacrylate and 0 to 150 parts by weight of etherified methylolmelamine in a solvent based on 100 parts by weight. 4. A method for protecting a painted surface according to claim 3, which comprises using a paint that is coated with a paint. 5. Claim 1, characterized in that the object to be coated is a resin mainly composed of methyl methacrylate.
Surface protection method for painted surfaces as described in section. 6. The surface protection method for a painted surface according to claim 1, wherein the object to be painted is made of polycarbonate resin. 7 The object to be painted is acrylonitrile-butadiene-
The method for protecting the surface of a painted surface according to claim 1, characterized in that styrene resin is used. 8. A surface protection method for a painted surface according to claim 1, wherein the object to be painted is a plastic molded product having a metal thin film.