JPS6052184B2 - paint composition - Google Patents

Description

Detailed Description of the Invention The present invention improves wear resistance, surface smoothness, flexibility, heat resistance, solvent resistance, and
The present invention relates to a coating composition capable of forming a crosslinked cured film with excellent durability and adhesion to a substrate.

Polymethyl methacrylate resin, polycarbonate resin, polyallyl diglycol carbonate resin, polystyrene resin, styrene-acrylonitrile copolymer resin (A
S resin), polyvinyl chloride resin, acetate resin, acrylonitrile-butadiene-styrene copolymer resin (AB
Compared to glass products, synthetic resin molded products made from S resin), polyester resin, etc. are not only lighter and have better impact resistance, but also have various advantages such as being cheaper and easier to mold. It is used in many fields such as organic plate glass, lighting equipment covers, optical lenses, eyeglass lenses, reflectors, mirrors, and other optical applications; signboards, displays, and other decorative applications; name plates, dust cover cases, and automobile parts. Development of its use is progressing.

However, these synthetic resin molded products lack surface wear resistance, so they are susceptible to contact with other objects, impact, and pulling during transport, when installing parts, or during use. This may damage the surface and reduce product yield.
The aesthetic appearance may be damaged.

In particular, molded products are used for cameras, optical lenses such as magnifying glasses, eyeglass lenses such as fashion glasses, sunglasses, corrective lenses, window glasses, decorative cases,
In the case of covers, watch lenses, reflectors, mirrors, etc., damage to the surface can significantly reduce its commercial value or render it unusable in a short period of time, so it is necessary to improve the abrasion resistance of the surface. is strongly required. Various methods have been studied to improve these drawbacks of synthetic resin molded products. For example, polyfunctional acrylates or methacrylates having two or more polymerizable ethylenically unsaturated groups in one molecule have been studied. There is a method in which a monomer is applied as a crosslinked cured paint to the surface of a synthetic resin molded article, and active energy rays are irradiated to form a crosslinked cured film on the surface of the synthetic resin molded article by radical polymerization.

Conventionally, such polyfunctional (meth)acrylate (acrylate or methacrylate, hereinafter the same) monomer has excellent polymerization activity when irradiated with active energy rays, so it has been used as a quick-drying ink material in the US Patent No. 36616
No. 14, No. 3551311, No. 3551246, or British Patent No. 11982, and these polyfunctional (meth)acrylate monomers are used for surface modification of synthetic resin molded articles. Regarding its application as a material, see US Pat. No. 3,552,986 and US Pat.
No. 3 or the specification of No. 3,770,490.

On the other hand, the present applicant and others have also discovered that polyfunctional (meth)acrylate monomers have excellent crosslinking and curing polymerizability upon irradiation with active energy rays, and that crosslinking can improve the abrasion resistance of the surface of synthetic resin molded products. He discovered that it was effective as a material for forming a cured film and made many proposals.
No. 2211, No. 49-12886, No. 49-2295
No. 1, No. 49-14859, No. 49-2295? Public bulletin).

The method of applying these polyfunctional (meth)acrylate monomers as a crosslinked curable paint to the surface of a synthetic resin molded product and irradiating it with active energy rays to form a crosslinked cured film on the surface of the synthetic resin molded product is as follows: Compared to the method of using a thermosetting paint to form a crosslinked cured film through heat treatment, the paint has better storage stability, and since it is polymerized and crosslinked by irradiation with active energy rays, it takes only minutes or seconds at room temperature. It is possible to form a cross-linked cured film in a short period of time, and it is excellent in terms of productivity.It also has excellent wear resistance in terms of performance, and there is no change in the cured film over time, and it has excellent water resistance, weather resistance, and base material. It has many advantages, including excellent initial adhesion to materials.

However, on the other hand, it has also been found that there are the following problems.

The first point is that after applying paint to the surface of a synthetic resin molded product, when irradiating it with active energy rays to form a crosslinked cured film, it is done in an inert gas atmosphere such as nitrogen gas or carbon dioxide gas. Otherwise, the crosslinking and curing reaction will be inhibited by oxygen in the air, and a crosslinked and cured film with sufficient wear resistance will not be formed. This is an extremely important problem in practical terms; it not only complicates the process, but also makes it difficult to keep the oxygen concentration in the atmosphere constant and low, leading to variations in performance and lower product yields. It may also cause an increase in costs. The second point is that many polyfunctional (meth)acrylate monomers have high viscosity at room temperature, and moreover, the more effective they are for improving wear resistance, the higher the viscosity becomes, resulting in poor coating workability and difficult coating methods. Not only are there limitations, but there are also operational problems such as insufficient surface smoothing of the cross-linked cured film, difficulty in controlling the film thickness, and other problems such as adhesion to the substrate, abrasion resistance, and surface smoothness. However, it is extremely difficult to form a thin crosslinked cured film with excellent film thickness uniformity. As mentioned above, synthetic resin molded products with a crosslinked cured film on the surface obtained by applying a polyfunctional (meth)acrylic monomer as a paint to the surface of a synthetic resin molded product and irradiating it with active energy rays have been improved. Currently, there are many problems that need to be addressed, and despite the useful advantages, it has not yet been put into practical use.

In view of these circumstances, the inventors of the present invention have conducted extensive research, and have found that they use a coating composition containing specific ingredients in specific proportions, apply this to the surface of a synthetic resin molded product, and obtain specific results. We have completed the present invention by discovering that the above-mentioned drawbacks can be solved all at once by irradiating active energy rays under these conditions to form a crosslinked cured film having a specific thickness range.

That is, the present invention is based on the following general formula (where n is O or 1-
4 integers, at least 3 of X are CH2=CR-C
(1) One group and the remaining are -0H groups.

R represents hydrogen or a methyl group. ) 35 to 95 parts by weight of a polyfunctional monomer (a) of mono- or polypentaerythritol poly(meth)acrylate having three or more (meth)acryloyloxy groups in one molecule and the following general formula In the formula, R1 is hydrogen or a methyl group, n is 0 or an integer from 1 to 5, and Y is an alkylene group having 6 or less carbon atoms, or an alkylene group in which one hydrogen atom is replaced with a hydroxyl group. It is. These Y are when n is 2 or more,
Take the same or different things. ) has 0 to 60 parts by weight of bifunctional monomer (b) and two or less (meth)acryloyloxy groups in one molecule, and has a boiling point of 15 at normal pressure.
0°C or higher, the viscosity at 20°C is 20 centipoise or lower, and there is a hydroxyl group and/or a cyclic ether bond and/or a chain ether bond between the side chain or two (meth)acryloyloxy groups in the molecule. Monomer (c) having 5 to 65
5 to 9 parts by weight of a monomer mixture (A) (total 100 parts by weight) consisting of parts by weight, and at least one organic solvent that is mixed with the monomer mixture (4) to form a homogeneous solution. (B)
95 to 1 part by weight and 0 to 10 parts by weight of the photomultiplier (C) (based on a total of 10 parts by weight of the monomer mixture (4) and the organic solvent (B)), and air. Among these, the present invention relates to a coating composition that can form a crosslinked cured film with excellent wear resistance and surface smoothness upon irradiation with active energy rays. The greatest feature of the coating composition of the present invention is that a specific trifunctional or higher functional (meta)
Acrylate monomers, specific bifunctional (meth)acrylate monomers, and specific bifunctional or less (meth)acrylate monomers are blended with an organic solvent in a specific ratio, and active energy rays are released under an air atmosphere. By irradiation, it is possible to form a transparent crosslinked cured film with excellent abrasion resistance, surface smoothness, flexibility, water resistance, heat resistance, chemical resistance, and adhesion to substrates.

General formula used in the present invention (where n is O or an integer of 1 to 4, at least three of X are CH2=CR-COO, and the rest are -0H groups).

R represents hydrogen or a methyl group. The polyfunctional monomer (a) of mono- or polypentaerythritol poly(meth)acrylate shown in It forms a highly cross-linked cured polymer that exhibits wear resistance. In the present invention, the polyfunctional monomer (a) represented by the above general formula (1) is used. In particular, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta. Particularly preferred are (meth)acrylate, dipentaerythritol hexa(meth)acrylate, etc. in terms of polymerization activity when irradiated with active energy rays in air and ease of handling based on low viscosity. The polyfunctional monomer (a) represented by the general formula (1) may be used alone or in combination of two or more. The proportion of polyfunctional monomer (a) used is 35 to 95 parts per 10 parts of monomer mixture (4).
Parts by weight are preferably 35 to 94 parts by weight. When the amount of the polyfunctional monomer (a) in the monomer mixture (4) is less than 35 parts by weight, a cured film with sufficient wear resistance cannot be obtained,
Moreover, if the amount exceeds 95 parts by weight, the smoothness of the coating will be poor, which is not preferable. Furthermore, in the present invention, even if a polyfunctional monomer has three or more (meth)acryloyloxy groups in one molecule, a polyfunctional monomer that does not satisfy the general formula (1), such as a Polyfunctional (meth)acrylates such as methylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, and pentaglycerol tri(meth)acrylate have poor polymerization activity when irradiated with active energy rays in air, resulting in a coating film. It is not used because sufficient crosslinking and curing cannot be achieved.

In addition, the bifunctional monomer (b) used in combination with the polyfunctional monomer (a) imparts flexibility to the crosslinked cured film without reducing its abrasion resistance, and improves its adhesion to the substrate. When irradiated with high activation energy, the monomer that imparts air curability is a bifunctional (meth)acrylate monomer represented by the following general formula.

(In the formula, R1 is hydrogen or a methyl group, and n is 0 or 1
It is an integer of ~5, and Y is an alkylene group having 6 or less carbon atoms, or an alkylene group in which one hydrogen atom is replaced with a hydroxyl group.

These Ys may be the same or different when n is 2 or more). In the compound represented by this general formula, if the number of carbon atoms in Y is 7 or more, or if the number of n is 6 or more, the wear resistance of the crosslinked cured coating may be poor, or the adhesion to the substrate may be poor. This is not desirable as it may cause a decrease in the value.

More preferred monomers include those in which Y has 3 or less carbon atoms and n has 3 or less carbon atoms. Specific examples of the bifunctional monomer (b) represented by the above general formula include, for example, 2
,2bis(4-acryloxyphenyl)propane,2,
2bis(4-methacryloxyphenyl)propane, 2,
2bis(4-acryloxyethoxyphenyl)propane, 2,2bis(4-methacryloxyethoxyphenyl)
Propane, 2,2bis(4-acryloxydiethoxyphenyl)propane, 2,2bis(4-methacryloxydiethoxyphenyl)propane, 2,2bis(4-acryloxypropoxyphenyl)propane, 2 , 2 screws (4
-methacryloxypropoxyphenyl)propane, 2,
2bis [4-acryloxy (2-hydroxypropoxy)
Phenyl]propane, 2,2bis[4-methacryloxy(2-hydroxypropoxy)phenyl]propane, 2
, 2bis[4-acryloxy(2-hydroxypropoxyethoxy)phenyl]propane, 2,2bis[4-methacryloxy(2-hydroxypropoxyethoxy)phenyl]propane, and the like. These monomers may be used alone or in combination of two or more within the composition range.

The usage ratio of these bifunctional monomers (b) represented by the general formula () is 0 to 6 parts by weight per 100 parts by weight of the monomer mixture (A).

If the amount of the bifunctional monomer (a) exceeds 6 parts by weight in the monomer mixture (4), the abrasion resistance of the crosslinked cured coating will decrease, which is not preferred.

In addition, it has two or less (meth)acryloyloxy groups in one molecule used in combination with a polyfunctional monomer, has a boiling point of 150°C or higher at normal pressure, and has a viscosity of 20 centipoise or lower at 20°C. Monomer (C) which has a hydroxyl group and/or a cyclic ether bond and/or a chain ether bond between side chains or two (meth)acryloyloxys in the molecule.
Monomer (C) [hereinafter simply referred to as monomer (C)] gives the formed coated surface a very smooth surface called a mirror surface after coating the molded product with the coating composition, and also gives the cured film flexibility and flexibility. Necessary to provide adhesion to the base material.

That is, in order to form an extremely smooth coating film after applying the coating composition of the present invention to a molded article,
It is desirable that the viscosity of the monomer mixture (4) is 1,000 centipoise or less, and in order to impart similar smoothness to the cured film after curing, flexibility, and adhesion to the substrate. It is necessary to use a monomer (C) that satisfies the above conditions. Specific examples of this monomer (C) include diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol dimethacrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl (
meth)acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 1,
4-Butylene glycol mono(meth)acrylate, ethoxyethyl(meth)acrylate, ethyl carbitol(meth)acrylate, 2-hydroxy-3-chloropropyl(meth)acrylate, dipropylene glycol di(meth)acrylate, butoxyethyl(meth)acrylate ) Acrylate, 1,4-butylene glycol mono(meth)
Examples include acrylate and dipropylene glycol di(meth)acrylate. These monomers (C) are particularly preferred because they have excellent polymerization activity in air.One type of these monomers (C) can be used alone, or two or more types can be mixed within the composition range. May be used.
The usage ratio of monomer (C) is monomer mixture CA) 100
It is 5 to 65 parts by weight. If the amount of monomer (C) in the monomer mixture (4) is less than 5 parts by weight, the viscosity of the coating composition cannot be sufficiently lowered, and a molded article with a smooth surface cannot be obtained. do not have. On the other hand, monomer (C) is 65
If the amount exceeds 1 part by weight, it is not preferable because a crosslinked cured coating having sufficient abrasion resistance cannot be obtained. Furthermore, if the boiling point of monomer (C) is lower than 150°C at normal pressure, when applying the coating composition to the surface of the molded product and curing it,
If the viscosity of the monomer (C) exceeds 20 centipoise at 20°C, the viscosity of the monomer mixture (4) cannot be effectively lowered. So I don't like it. The above is the monomer mixture (4) constituting one component of the coating composition used in the present invention.
), but if necessary, within the range where these constituent conditions are met, it may be used for the purpose of imparting antistatic properties, antifogging properties, or other functions to the crosslinked cured film formed. At least one other monofunctional vinyl monomer that is copolymerizable with these monomer mixtures and has polymerization activity with active energy rays may be used in combination.

The organic solvent (B) used in combination with the monomer mixture (4) constituting the coating composition of the present invention improves coating workability and uniform coating when coating the coating composition on the surface of a synthetic resin molded article. It is used to impart extremely favorable effects on film formation properties or storage stability, and to dramatically increase the adhesion of crosslinked cured films to substrates.

In the present invention, the organic solvent used is a monopolyfunctional (meth)acrylate monomer mixture. to form a homogeneous solution.

2 The boiling point at normal pressure is 50°C or higher and 200°C or lower.

3.The viscosity at room temperature is 10 centipoise or less. 4
Polyfunctional (meth)acrylate monomer mixture (A) 5-
It is used at a ratio of 95 to 10 parts by weight (total 10 parts by weight) to 90 parts by weight.

It is necessary to satisfy the following conditions.

First, a polyfunctional (meth)acrylate monomer mixture (4)
The first condition is to form a uniform solution. For example, saturated hydrocarbon organic solvents such as n-hexane, n-heptane, and cyclohexane cannot be used because they do not form a uniform solution. 2nd boiling point at normal pressure of 50'C or higher 20
The condition of 0° C. or lower is an important and necessary requirement for forming a crosslinked cured film with excellent uniform film-forming properties or surface smoothness when applied to the surface of a synthetic resin molded article.
If the boiling point at normal pressure is less than 50°C, after the coating composition is applied, the substrate surface is cooled by the latent heat of the organic solvent that evaporates from the coating film, and moisture in the air condenses there, causing the coating film to deteriorate. In addition, if the temperature exceeds 200°C, the organic solvent evaporates from the coating film very slowly, resulting in workability problems, and residual organic solvents may be removed during the active energy ray irradiation process. The uniformity and surface smoothness of the cross-linked cured film may be lost due to an imbalance between the volatilization and escape of the compound and the formation of a cross-linked cured film through polymerization, or the organic solvent may remain in the cross-linked cured film, resulting in whitening of the film. So I don't like it. Therefore, the boiling point of the organic solvent used is 50°C or more at normal pressure.
It must be 0°C or lower, more preferably 60°C.
~150°C. In addition, the viscosity of the organic solvent used must also be 10 centipoise or less; if it exceeds 10 centipoise, the viscosity of the coating composition will increase and the coating properties and cross-linked cured film performance will deteriorate, so it is preferable. do not have.

The amount of organic solvent to be used is preferably in the range of 95 to 1 part by weight (total 100 parts by weight) per 5 to 9 parts by weight of the monomer mixture (A), and if it is less than 1 part by weight, Due to the high viscosity of the coating composition, coating workability is poor, making it difficult to control the thickness of the applied film, and reducing the ability to form a uniform film.
Furthermore, the adhesion of the crosslinked cured coating to the substrate also decreases under severe conditions.

On the other hand, if it exceeds 95 parts by weight, it is difficult to control the thickness of the crosslinked cured film, resulting in loss of surface smoothness and poor abrasion resistance, which is not preferred. Depending on the article on which a cross-linked cured film is formed, the cross-linked cured film is required to have extremely high surface smoothness, flexibility, and thinness of the film.

To this end, it is extremely important in practice to adjust the viscosity of the coating composition to improve coating workability and uniformity of the coated film, and to facilitate control of film thickness. In such cases, the viscosity of the coating composition should be controlled by adjusting the blending ratio of each component monomer in the monomer mixture and the amount of organic solvent used, and the method of forming the coating film should be adjusted according to the purpose. You need to choose. The type of organic solvent used must satisfy the conditions mentioned above, specifically alcohols such as ethanol, isopropanol, normal propanol, isobutyl alcohol, normal butyl alcohol, and aromatic substances such as benzene, toluene, xylene, and ethylbenzene. Examples include group hydrocarbons, ketones such as acetone and methyl ethyl ketone, ethers such as dioxane, and acid esters such as ethyl acetate, n-butyl acetate, and ethyl propionate.

These organic solvents may be used alone or in combination of two or more as long as the boiling point and component ratio of the mixture meet the above requirements. . Depending on the type of synthetic resin used as the base material, these organic solvents may
It may cause the haze value of materials used for transparent purposes, cause discoloration by dissolving dyes and pigments from colored base materials, or cause cracks to occur in the base material itself.
The type of organic solvent to be used is desirably selected as appropriate depending on the type or purpose of the substrate on which the crosslinked cured film is to be formed.

Applying the coating composition of the present invention to the surface of a synthetic resin molded article,
In order to form a crosslinked cured film, it is necessary to irradiate active energy rays such as ultraviolet rays, electron beams, or radiation.

Among these, the method using ultraviolet irradiation is the most preferred crosslinking and curing method from a practical standpoint. When ultraviolet rays are used as energy rays for crosslinking and curing coatings, it is necessary to add to the coating composition a photosensitizer that can initiate a polymerization reaction upon irradiation with ultraviolet rays.

Specific examples of such photomultipliers include carbonyl compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, acetoin, butyroin, toluoin, benzyl, benzophenone, p-chlorobenzophenone, and p-methoxybenzophenone. compounds, sulfur compounds such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide, azo compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile,
Examples include peroxide compounds such as benzoyl peroxide and ditertiary butyl peroxide. These photosensitizers may be used alone or in combination of two or more. The amount of these photosensitizers added to the coating composition is 0 to 1 part by weight, preferably 0.0 to 1 part by weight, based on a total of 10 parts by weight of the monomer mixture (4) and the organic solvent (B).
It is in the range of 01 to 1 part.

Addition of too large a quantity is not preferable since it may cause coloring of the crosslinked cured film or a decrease in weather resistance. Furthermore, additives such as antistatic agents, surfactants, ultraviolet absorbers, and storage stabilizers may be appropriately added to the coating composition of the present invention as required.

Next, a wear-resistant synthetic resin molded article is manufactured using the above-mentioned coating composition by applying the coating composition to the surface of the synthetic resin molding and then irradiating it with active energy rays. .

The synthetic resin molded products used to produce wear-resistant synthetic resin molded products using the coating composition of the present invention include various synthetic resin molded products including thermoplastic resins and thermosetting resins;
For example, sheets made from polymethyl methacrylate resin, polycarbonate resin, polyallyl diglycol carbonate resin, polystyrene resin, acrylonitrile-styrene copolymer resin (AS resin), polyvinyl chloride resin, acetate resin, ABS resin, polyester resin, etc. Specific examples include molded products, film-shaped molded products, rod-shaped molded products, and various injection molded products.

Among these molded products, molded products manufactured from polymethyl methacrylate resin, polycarbonate resin, polyallyl diglycol carbonate resin, etc. are used to take advantage of their properties such as optical properties, heat resistance, and impact resistance. In many cases, there is a strong demand for improved wear resistance.
These molded articles are particularly preferred as synthetic resin molded articles used in the present invention. The various molded products described above can be used as they are, but if necessary, they can be cleaned, etched, corona discharged, irradiated with active energy rays, etc.
Materials that have undergone pretreatment such as dyeing or printing can also be used. Furthermore, methods such as brush coating, flow coating, spray coating, spin coating, or dip coating are employed as methods for applying the above-mentioned coating composition to the synthetic resin molded article.

Each method has its advantages and disadvantages, and the application method must be selected appropriately depending on the required performance of the synthetic resin molded article or its intended use. For example, if you want to impart wear resistance to only a part of the desired synthetic resin molded product, brush coating or flow coating is suitable, whereas if the surface shape of the molded product is complex, spray coating or molded product is suitable. Spin coating is suitable for flat and symmetrical shapes, and dip coating is suitable for molded products in the form of rods or sheets. The amount of the coating composition to be applied to the surface of the synthetic resin molded article varies depending on the amount of monomer mixture (4) contained in the coating composition and the purpose, but the amount of coating composition applied to the surface of the synthetic resin molded article varies depending on the amount of monomer mixture (4) contained in the coating composition and the purpose. The film thickness of the cross-linked cured film is 1~
It is necessary to apply the coating to a range of 30μ.

The corresponding coating amount of the coating composition is approximately 1.5 to 3
The coating film may be made to have a coating thickness of 00 μm. If the thickness of the cross-linked cured film formed on the surface of a synthetic resin molded product is less than 1 μm, the wear resistance will be poor, and if it exceeds 30 μm, the hardened film will have poor flexibility and cracks will easily occur. This is not preferable because it may cause a decrease in the strength of the molded product itself.

As mentioned above, there are various methods for applying the coating composition, but among them, the dip coating method is limited to some extent depending on the shape of the synthetic resin molded product, but the coating process is The process is simple, there is little loss of the coating composition, and there are advantages such as excellent workability and productivity as well as excellent reproducibility.

However, in order for dip coating to be possible and to take advantage of its advantages, the paint used must meet the following conditions. is necessary. In other words, the viscosity of the paint is low and the coating film can be formed easily by dipping, the thickness of the coating film can be controlled, and the reproducibility is excellent.
The viscosity of the paint does not change over time and has excellent storage stability! It is required to do the following.

The coating composition used in the present invention satisfies these requirements when its viscosity at 20°C is 15 centipoise or less, and has good abrasion resistance, surface smoothness, film thickness uniformity, flexibility, durability, A transparent crosslinked cured film with excellent water resistance, heat resistance, solvent resistance, and adhesion to substrates is formed, and has excellent adaptability to dip coating. Depending on the use of synthetic resin molded products with a cross-linked cured coating formed on the surface, after the cured coating has been formed, the product may be subjected to bending under appropriate heating, or may be subjected to machining such as cutting and drilling. It is also required to withstand severe conditions such as large deformation and strain being applied during parts installation or use.

In such cases, it is naturally necessary that the crosslinked cured coating itself has excellent properties such as flexibility and adhesion to the base resin, but the second factor is the thickness of the cured coating. . In other words, the thinner the film is, the better it is, but on the other hand, if it becomes extremely thin, the abrasion resistance will decrease, so in such a case, the cross-linked cured film should have a thickness of 1 to 9 μm. Preferably within this range. At the technical level of using conventional polyfunctional (meth)acrylate monomers or mixtures thereof as cross-linked cured film forming materials, they have excellent wear resistance, surface smoothness, film thickness uniformity, transparency, and film formation. It has been impossible to form such a thin cross-linked cured film with excellent appearance on the surface of a synthetic resin molded product.

However, in the coating composition used in the present invention, 20
A coating composition prepared to have a viscosity of 15 centipoise or less at °C is applied to the surface of a synthetic resin molded article by dip coating, and crosslinked and cured to improve wear resistance,
It has become possible to form a transparent crosslinked cured film with a thickness of 1 to 9 μm and excellent in surface smoothness, film thickness uniformity, film appearance, and adhesion to the substrate.

This is one of the most important points of the invention. In the step of irradiating active energy rays, the coating applied to the surface of the synthetic resin molded product is cured by irradiating the coating with activation energy rays, but preferably under specific conditions before crosslinking and curing with active energy rays. The organic solvent (B) contained in the paint coating applied to the surface of the synthetic resin molded product was
It is better to irradiate active energy rays after volatilizing more than % of the slag.

If active energy rays are applied to a coated film containing 5% or more of organic solvent, the surface smoothness of the cross-linked cured film may be impaired, bubbles may appear in the film, or cross-linked hardening may occur depending on the type of organic solvent. If organic solvent remains in the coating,
This is undesirable as it causes phenomena such as whitening of the film.
In order to crosslink and cure the applied film, ultraviolet rays emitted from a light source such as a xenon lamp, low pressure mercury lamp, high pressure mercury lamp, or ultra-high pressure mercury lamp, or electron beams, α rays, β rays, usually extracted from an electron beam accelerator of 20 to 2000 K, γ
must be irradiated with active energy rays such as rays.
From the point of view of practicality or workability, ultraviolet light is the most preferred radiation source. The atmosphere for irradiating active energy rays may be an inert gas atmosphere such as nitrogen gas or carbon dioxide gas, or an atmosphere with a reduced oxygen concentration, but the coating composition according to the present invention can be
It is possible to form a crosslinked cured film with excellent wear resistance and other properties even in an air atmosphere.

The temperature of the irradiation atmosphere may be room temperature, or may be an atmosphere heated to such an extent that no harmful deformation occurs to the base synthetic resin molded article. J The coating composition of the present invention and the synthetic resin molded product having a crosslinked cured film on the surface produced using the same have excellent surface smoothness and aesthetic appearance, and extremely excellent surface hardness, abrasion resistance, and scratch resistance. It is something that Furthermore, the cross-linked cured film formed on the surface is a transparent, flexible, and uniform film that has extremely good adhesion to the base material, causing peeling and cracking of the film even under harsh conditions and environments. Without organic window glass,
It is extremely useful for uses such as lighting equipment covers, reflectors, mirrors, eyeglass lenses, sunglass lenses, and optical lenses. The contents of the present invention will be explained in more detail below with reference to Examples.

In addition, the measurement evaluation in the examples was performed by the following method.
(1) Abrasion resistance a Surface hardness... Pencil hardness b according to JIS K565l-1966 Scratch test... Scratch test with #000 steel wool 0...
...Even if you rub it lightly, there will be almost no scratches on the surface.Δ...If you rub it lightly, the surface will be slightly scratched.
Damaged: Even if rubbed lightly, the surface will be seriously scratched (same level as the base resin) (2) Cross-cut cellotape peel test on adhesive crosslinked cured film.

In other words, the film cutting line that reaches the base material at 1wn intervals is made by 11 people vertically and horizontally to make 10 grids of 1i, and zero tape is pasted on it and peeled off rapidly. Repeat this zero tape operation three times at the same location. 0
...No peeling of the cross-linked cured film even after repeating 3 times Δ...Number of peeling after repeating 3 times 1
~ 5 proboscis ×...Number of peeling lines after repeating 3 times 51 ~ 10 (3) Flexibility (maximum bending angle) Cross-linking on the surface of sheet-like molded products of 2 to 3 thicknesses After forming a hardened film, cut out a strip-shaped test piece with a width of 6 m and a length of 5 d, and apply force from both ends of this strip to give it bending deformation strain. Find the angle.

This is the "maximum bending angle", and the larger this angle, the better the flexibility of the coating. (4) Thermal and cycle test A molded product with a cross-linked cured film formed on its surface is immersed in hot water at 65°C for 1 hour, then immediately immersed in ice water at 0°C for 10 minutes, and then dried with hot air at 80°C for 1 hour. .

After repeating this several times, perform each type of test. (5) Surface smoothness measurement: 0...The surface smoothness of the coating was very good and mirror
It can be said to be a face.

Δ...The surface smoothness of the coating is good but slightly
There is a strange disturbance and it cannot be called a mirror surface.

×...The surface is disordered and the smoothing is poor.

Example 1 A curing solution as shown in Table 1 was prepared, and 2
? A methacrylic resin plate (manufactured by Mitsubishi Rayon, trade name: Acrylite) was immersed, and the plate was pulled up at a speed of 0.5 cm/Sec to form a film. After being left as is, the board coated with the coating composition was irradiated with ultraviolet rays from a high-pressure mercury lamp (2KWH01L2L manufactured by Iwasaki Electric Co., Ltd.) for a duration of 20 seconds on each side of the board in the atmosphere listed in Table 1 from a distance of 20CWL. The results obtained are shown in Table 1. As shown in Experiment No. 1 in Table 1, the coating composition of the present invention exhibits crosslinking curability comparable to that in an inert atmosphere of nitrogen gas. Furthermore, it can be seen that when trifunctional (meth)acrylates other than those of the present invention are used as in Experiment No. 4, crosslinking and curing in air does not occur.

Example 2 A methacrylic resin plate of 2 T$t was immersed in a coating composition as shown in the table, and the plate was pulled up at a speed of 0.5 cm/Sec to form a coating.

After leaving it as it was for 1 minute, it was irradiated with ultraviolet rays from a high-pressure mercury lamp (Iwasaki Electric 2KWH0 upper model 21) in an air atmosphere for 158' from a distance of 20 cm on each side of the board. The results obtained are also shown in the table. As is clear from the table, coating compositions that do not meet the conditions of the present invention (Experiment Nos. 2, 3 and 4)
The surface of the cured paint film was poor in smoothness, and a mirror surface could not be obtained.

Example 3 70 parts by weight of dipentaerythritol pentaacrylate, 1 part of 2,2bis(4-acryloxyphenyl)propane
A part by weight of saliva, 2 parts by weight of tetrahydrofurfuryl acrylate, 2 parts by weight of isopropyl alcohol, and 4 parts by weight of benzoin isobutyl ether were stirred and mixed, and the resulting coating composition was applied to a 2 mm thick methacrylic resin cast plate using a percoater. It was applied evenly using

After being allowed to stand for 5 minutes, ultraviolet rays from a 2KW high-pressure mercury lamp were irradiated in the air for 1 circle and 2 hours from both sides at a distance of 20CTn from the coated surface.

As is clear from the table, it is clear from the table that the flexibility of the cross-linked cured film is poor when the film thickness is as thick as 35 μm. Example 4 1 part by weight of pentaerythritol tetraacrylate, 18 parts by weight of pentaerythritol triacrylate, 2,
A coating composition consisting of 5 parts by weight of 2-bis(4-acryloxydiethoxyphenyl)propane, 7 parts by weight of 2-hydroxypropyl acrylate, 60 parts by weight of t-butyl alcohol and 2 parts by weight of benzoin ethyl ether was added as shown in the table. Immerse various synthetic resin molded plates at 0.6 cm/Sec.
The plate was pulled up at a speed of 100 to form a coating.

After leaving to stand for 5 minutes, one gill was irradiated on both sides from a distance of 20 cm using a 2 KW high pressure mercury lamp in the air.

The appearance of the various molded plates on which the crosslinked cured coating was formed was good, and the other properties of the coating were also good as shown in the table.

Example 5 15 parts by weight of dipentaerythritol hexaacrylate, 45 parts by weight of dipentaerythritol pentaacrylate, 1 part by weight of dipentaerythritol tetraacrylate, 5 parts by weight of 2,2bis(4-acryloxydiethoxyphenyl)propane, Solution A is a mixture of 25 parts by weight of tetrahydrofurfuryl acrylate and 4 parts by weight of benzoinpropyl ether, and Solution B is a mixture of 80 parts by weight of isopropyl alcohol and 2 parts by weight of toluene.
Make it into a liquid.

Liquids A and B were mixed in the proportions shown in Table V to obtain a uniform coating composition.

A cast molded plate made of methacrylic resin having a thickness of 37 m was immersed in these compositions, and then slowly pulled up at a speed of 0.5 cm/Sec to form a coating film of the composition on the surface of the molded plate.

After one molding, these were irradiated with ultraviolet rays from a 2KW high-pressure mercury lamp in air for one forge from a distance of 20C71 cm on both sides to form a crosslinked hardened film on the surface of the molded plate.

Various performances of the obtained molded products were measured and the evaluation results are shown in the table. As is clear from these results, the dip coating method allows relatively easy adjustment of the thickness of the crosslinked cured film by adjusting the viscosity of the coating composition, and has excellent surface smoothness and uniformity.

In particular, when the viscosity of the coating composition at 20° C. is 15 centipoise or less, the film thickness is thin and the film has excellent smoothness and flexibility.

However, when the thickness of the crosslinked cured film is extremely thin as in Experiment No. 1, the film has excellent flexibility and adhesion, but its abrasion resistance decreases. Example 6 7 parts by weight of dipentaerythritol hexaacrylate,
2 parts of dipentaerythritol pentaacrylate,
Pentaerythritol triacrylate 5 parts by weight, 2-
5 parts of the organic solvent shown in the table was added to a mixture of monomer and sensitizer, 8 parts by weight of hydroxyethyl acrylate and 2 parts by weight of benzoin ethyl ether.
A homogeneous coating composition was prepared by adding and mixing by weight.

Thickness 2w in these compositions! A methacrylic resin cast plate of No. n was immersed and slowly pulled up to form a coating film on the surface of the molded plate. These were cured in air in the same manner as in Example 5 to form a crosslinked cured film on the surface of the molded article. Various performances of the obtained molded product were measured and the evaluation results are shown in the table.

As is clear from the results in the table, the use of organic solvents other than those used in the present invention is undesirable, as the coating film forming properties and the appearance of the cured film may deteriorate.

Example 7 A coating composition as shown in the table was prepared and applied to a thickness of 3w1.
The outer surface of a conical methacrylic resin injection molded product with a radius of n1 of 607T0111 and a height of 5'' was spray coated to form a coating having an average thickness of approximately 20μ.

Leave this in an air atmosphere for 3 minutes, and then
A cross-linked cured film having an average thickness of about 11 μm was formed on the outer surface of the molded product by irradiating it with ultraviolet rays from a 2 KW high-pressure mercury lamp from a distance of 100 m. Abrasion resistance of the outer surface of the molded product obtained,
Both adhesion and film smoothness were good.

Example 8 24 parts by weight of dipentaerythritol pentaacrylate, 2,2 bis(4-acryloxypropoxyphenyl)
Obtained by stirring and mixing 4 parts by weight of propane, 5 parts by weight of tetrahydrofurfuryl acrylate, 2 parts by weight of 2-hydroxypropyl acrylate, 65 parts by weight of isopropyl alcohol, 0.8 parts by weight of benzophenone and 1.2 parts by weight of benzoin isobutyl ether. 3T in paint composition
0.6CT by dipping a polycarbonate extrusion plate of En thickness
The plate was pulled up at a pulling rate of n/Sec to form a coating.

After 10 minutes, apply ultraviolet rays from a 2KW high-pressure mercury lamp to both sides.
It was cross-linked and cured by irradiation for 9 seconds from a distance of 50 mm.

The appearance of the obtained film was very good, the film thickness was 3.5μ, the abrasion resistance was as high as the pencil hardness, and no scratches were observed in the steel wool abrasion test.

Regarding adhesion, no peeling occurred before and after the thermal cycle test. Example 9 5 parts by weight of dipentaerythritol hexaacrylate,
1 part of dipentaerythritol pentaacrylate,
6 parts by weight of pentaerythritol triacrylate, 7 parts by weight of ethoxyethyl acrylate, 5 parts by weight of ethyl alcohol
A polyallyl diglycol carbonate lens was immersed in a coating composition prepared by stirring and mixing 20 parts by weight of xylene, 1 part by weight of benzophenone, and 1 part by weight of benzoin ethyl ether for 5 minutes to produce a coating composition of 0.45 cm/Sec. I slowly pulled it up.

After one shot, this lens was irradiated with a 6KW high-pressure mercury lamp from a distance of 20 cm on both sides.

The thickness of the cross-linked cured film of the obtained lens is 3.4μ, and what is its abrasion resistance? It showed no scratches in the steel wool abrasion test. As for the adhesion of the coating, there was no peeling in the cross-cut zero tape test, and the coating had a mirror-like smoothness and was completely usable as an optical product. Example 10 2 parts by weight of pentapentaerythritol dodeca acrylate, 9 parts by weight of dipentaerythritol hexaacrylate, 1 part by weight of dipentaerythritol pentaacrylate, 9 parts by weight of dipentaerythritol tetraacrylate, 1 part by weight of tetrahydrofurfuryl acrylate, isopropyl A methacrylic resin plate with a smooth surface was immersed in a composition consisting of 4 parts by weight of acrylate, 2 (2) parts by weight of toluene, and 2 parts by weight of benzyl dimethyl ketal, and then pulled up at a rate of 0.5/Sec.

Claims (1)

[Claims] 1% Formula % (I) (wherein n is 0 or an integer of 1 to 4, at least 3 of X are CH_2=CR-COO- groups and the rest are -OH groups. R represents hydrogen or a methyl group.) Polyfunctional monomer (a) 35 of mono- or polypentaerythritol poly(meth)acrylate having three or more (meth)acryloyloxy groups in one molecule ~95 parts by weight and the following general formula % formula % (II) (wherein R_1 is hydrogen or a methyl group, n is 0 or an integer from 1 to 5, and Y is an alkylene group having 6 or less carbon atoms. or one hydrogen atom of the alkylene group is substituted with a hydroxyl group.When n is 2 or more, these Y are the same or different.) Bifunctional monomer (b) 0 ~60 parts by weight and two or less (meth)acryloyloxy groups in one molecule, a boiling point at normal pressure of 150°C or more, a viscosity at 20°C of 20 centipoise or less, and A monomer mixture (A) consisting of 5 to 65 parts by weight of a monomer (c) having a hydroxyl group and/or a cyclic ether bond and/or a chain ether bond between side chains or two (meth)acryloyloxy groups. ) (100 parts by weight in total), 95 to 10 parts by weight of at least one organic solvent (B) which is mixed with the monomer mixture (A) to form a homogeneous solution, and photosensitization. Agent (C) 0 to 10 parts by weight (the monomer mixture (
(based on a total of 100 parts by weight of A) and organic solvent (B))
A coating composition that can form a crosslinked cured film with excellent wear resistance and surface smoothness by irradiation with active energy rays in air. 2 The polyfunctional monomer is pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tri(
meth)acrylate, dipentaerythritol tetra(
meth) acrylate, dipentaerythritol penta(
meth)acrylate, dipentaerythritol hexa(
The coating composition according to claim 1, which is a meth)acrylate. 3. The coating composition according to claim 1, wherein the monomer mixture has a viscosity of 1,000 centipoise or less at 20°C. 4. The coating composition according to claim 1, wherein the organic solvent has a boiling point at normal pressure of 50°C or more and 200°C or less, and a viscosity at 20°C of 10 centipoise or less. 5. The coating composition according to claim 1, wherein the coating composition has a viscosity of 15 centipoise or less at 20°C. 6 The amount of photosensitizer used is 0.01 to 10 parts by weight,
2. The coating composition according to claim 1, wherein the active energy ray is an ultraviolet ray.