JPS6367809B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a synthetic resin molded article with improved wear resistance. Polymethyl methacrylate resin, polycarbonate resin, polyallyl diglycol carbonate resin, polystyrene resin, styrene-acrylonitrile copolymer resin (AS resin), polyvinyl chloride resin, acetate resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), Synthetic resin molded products made from polyester resin etc. are not only lighter and have better impact resistance than glass products, but also have various advantages such as being inexpensive and easy to mold. Its applications include optical applications such as plate glass, lighting equipment covers, optical lenses, eyeglass lenses, reflectors, and mirrors, decorative applications such as signboards and display displays, and many other fields such as name plates, dust cover cases, and automobile parts. Development is underway. However, these synthetic resin molded products lack surface wear resistance, so they are susceptible to contact with other objects, collisions, and scratches during transport, when installing parts, or during use. As a result, the surface is damaged, reducing product yield and deteriorating the aesthetic appearance. In particular, molded products are used for cameras, optical lenses such as magnifying glasses, optical lenses such as fashion glasses, sunglasses, corrective lenses, or window glass, decorative cases and covers, watch lenses, reflectors, and mirrors. In such cases, the damage that occurs to the surface may significantly reduce its commercial value, or
Since it becomes unusable in a short period of time, there is a strong need to improve the wear resistance of the surface. Various methods have been studied to improve these drawbacks of synthetic resin molded products. For example, one method is to apply a silicone-based paint or melamine-based paint to the surface of a synthetic resin molded product and heat-cure it. There is a method of forming a so-called thermosetting crosslinked cured film on the surface of a synthetic resin molded product. However, since these methods are thermosetting, the storage stability of the paint is not good, and it is necessary to heat the paint at high temperature for a long time to form a crosslinked cured film, which reduces workability and productivity. Unfortunately, even after cross-linking and curing treatment, the curing reaction proceeds gradually, resulting in cracks in the cross-linked cured film after it is commercialized, or cracks at the interface with the substrate, resulting in poor adhesion to the substrate. There are performance disadvantages such as decreased properties and water resistance and weather resistance. Another method is to apply a polyfunctional acrylate or methacrylate monomer having two or more polymerizable ethylenically unsaturated groups in one molecule to the surface of a synthetic resin molded product as a crosslinked and cured coating.
There is a method in which a crosslinked cured film is formed by radical polymerization on the surface of a synthetic resin molded article by irradiating it with active energy rays. Conventionally, such polyfunctional acrylate or methacrylate monomers have excellent polymerization activity when irradiated with active energy rays, so they have been used as quick-drying ink materials as described in U.S. Pat. Nos. 3,661,614 and 3,551,311.
No. 3551246 or British Patent No. 1198259
Regarding the application of these polyfunctional acrylate or methacrylate monomers as surface modification materials for synthetic resin molded products, U.S. Pat. No. 3,552,986, U.S. Pat. This is proposed in Specification No. 3770490, etc. On the other hand, the present applicants have also discovered that polyfunctional acrylate or methacrylate monomers have excellent crosslinking and curing polymerizability upon irradiation with active energy rays, and that this crosslinking and curing can improve the surface abrasion resistance of synthetic resin molded articles. He discovered that it was effective as a film-forming material and made many proposals.
No. 49-12886, No. 49-22951, No. 49-
14859, Publication No. 49-22952). The method of applying these polyfunctional acrylate or methacrylate 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 described above. Compared to the method of forming a crosslinked cured film by heat treatment using a thermosetting paint, the storage stability of the paint is better, and since it is polymerized and crosslinked by irradiation with active energy rays, it can be cured in minutes or at room temperature. It is possible to form a cross-linked cured film in a short time on the order of seconds, 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 It has many advantages such as excellent initial adhesion to the base material. 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 can also cause an increase in costs. The second point is that many polyfunctional acrylate or methacrylate monomers have high viscosity at room temperature, and the more effective they are for improving wear resistance, the higher the viscosity becomes, resulting in poor coating workability and limited coating methods. In addition, there are operational problems such as the surface smoothness of the cross-linked cured film being insufficient, poor uniformity of film thickness, and difficulty in controlling the film thickness, and other problems such as poor adhesion to the substrate. It is extremely difficult to form a thin crosslinked cured film with excellent properties such as hardness, abrasion resistance, surface smoothness, and film thickness uniformity. As mentioned above, it is possible to improve synthetic resin molded products having a cross-linked cured coating on the surface obtained by applying a polyfunctional acrylate or methacrylate monomer as a paint to the surface of a synthetic resin molded product and irradiating it with active energy rays. Currently, there are many problems that need to be addressed, and although there are 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. The present invention has been completed by discovering that the above-mentioned problems can be solved at once by irradiating active energy rays under the following conditions to form a crosslinked cured film having a specific thickness range. That is, the present invention provides pentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, dipentaerythritol triacrylate, dipentaerythritol trimethacrylate, dipentaerythritol tetraacrylate, dipentaerythritol tetramethacrylate, dipentaerys little pentaacrylate,
dipentaerythritol pentamethacrylate,
30 to 98% by weight of at least one polyfunctional monomer selected from the group consisting of dipentaerythritol hexaacrylate and dipentaerythritol hexamethacrylate and the following general formula (In the formula, R ₁ is hydrogen or a methyl group, n is 0 or an integer of 1 to 5, and X is an alkylene group having 6 or less carbon atoms or 1 hydrogen atom of the alkylene group.
are substituted with hydroxyl groups, and these are n
may be the same or different when is 2 or more. 100 parts by weight of a monomer mixture [A] consisting of 70 to 2% by weight of a bifunctional monomer represented by ) and 0 to 10 parts by weight of a photosensitizer. A coating composition capable of forming a crosslinked cured film with excellent abrasion resistance is applied to the surface of a synthetic resin molded product,
The present invention relates to a method for producing a synthetic resin molded article with improved abrasion resistance, characterized in that a crosslinked cured coating with a thickness of 1 to 30 microns is formed by irradiating the article with active energy rays. The greatest feature of the present invention is the use of a composition containing a specific polyfunctional (meth)acrylate monomer, a specific bifunctional (meth)acrylate, and a photosensitizer in a specific ratio as a paint. As a result, for the first time, the objects of the present invention can be achieved, including abrasion resistance, surface smoothness, flexibility, water resistance, heat resistance, chemical resistance, and substrate resistance even when irradiated with active energy rays in an air atmosphere. A synthetic resin molded product having a transparent crosslinked cured film with excellent adhesion can be obtained, and it is possible to obtain a synthetic resin molded article having a transparent crosslinked cured film with excellent adhesion, and it is possible to use polyfunctional monomers or bifunctional monomers other than those according to the present invention, or to use a blended composition thereof. If the ratios are different, the crosslinking and curing reaction in an air atmosphere may be inhibited, the abrasion resistance and flexibility of the crosslinked cured film may be poor, or the adhesion to the substrate may be reduced, resulting in the above-mentioned problems. A synthetic resin molded article with well-balanced various performances cannot be obtained, and the object of the present invention cannot be achieved. The above-mentioned polyfunctional monomer is a monomer that has air curability and at the same time imparts a high degree of abrasion resistance to the crosslinked cured film formed when irradiated with active energy rays. Examples include pentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, dipentaerythritol triacrylate, dipentaerythritol trimethacrylate, dipentaerythritol tetraacrylate, dipentaerythritol tetramethacrylate, Examples include pentaerythritol pentaacrylate, dipentaerythritol pentamethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol hexamethacrylate, and the like. These can be used alone or in a mixture of two or more. Even if they are the same polyfunctional acrylate monomers, polyfunctional ones such as trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, trimethylolethane triacrylate, trimethylolethane trimethacrylate, pentaglycerol triacrylate, pentaglycerol trimethacrylate, etc. Monomers are not preferred because they have poor air curability with active energy rays, and therefore it is difficult to form a crosslinked cured film with excellent abrasion resistance in an air atmosphere. The proportion of polyfunctional monomer used in the paint composition is 30~
It needs to be in the range of 98% by weight, preferably 40-96% by weight. If the usage rate is less than 30% by weight, a crosslinked cured coating with sufficient wear resistance will not be formed, and if it exceeds 98% by weight, there will be no problem in terms of wear resistance, but the crosslinked cured coating will not be formed. Since the flexibility and adhesion of the synthetic resin base material are reduced, undesirable phenomena such as cracking and film peeling occur. In addition, the bifunctional monomer used in combination with the polyfunctional (meth)acrylate monomer imparts flexibility to the crosslinked cured coating without reducing its abrasion resistance.
When irradiating active energy while increasing adhesion to a substrate, a bifunctional acrylate or methacrylate monomer is a monomer that imparts air curability and is represented by the following general formula. (In the formula, R ₁ is hydrogen or a methyl group, n is 0 or an integer from 1 to 5, and X is an alkylene group having 6 or less carbon atoms, or one hydrogen atom of the alkylene group is substituted with a hydroxyl group. (These may be the same or different when n is 2 or more.) In the compound represented by this general formula, when the number of carbon atoms in X is 7 or more, or the number of n is 6 or more, This is undesirable because the abrasion resistance of the crosslinked cured coating may be poor or the adhesion to the substrate may be reduced. More preferred monomers include those in which X has 3 or less carbon atoms and n has 3 or less carbon atoms. Specific examples of the bifunctional monomer represented by the above general formula include 2,2bis(4acryloxyphenyl)propane, 2,2bis(4methacryloxyphenyl)propane, and 2,2bis(4methacryloxyphenyl)propane. 4 acryloxyethoxyphenyl)propane, 2,2bis(4methacryloxyethoxyphenyl)propane,
2,2bis(4acryloxydiethoxyphenyl)propane, 2,2bis(4methacryloxydiethoxyphenyl)propane, 2,2bis(4acryloxypentaethoxyphenyl)propane,
2,2bis(4methacryloxypentaethoxyphenyl)propane, 2,2bis(4acryloxypropoxyphenyl)propane, 2,2bis(4methacryloxypentaethoxyphenyl)propane
methacryloxypropoxyphenyl) propane,
2,2bis[4acryloxy(2hydroxypropoxy)phenyl]propane, 2,2bis[4methacryloxy(2hydroxypropoxy)phenyl]propane, 2,2bis[4acryloxy(2hydroxypropoxy)phenyl]propane
Examples include hydroxypropoxyethoxy)phenyl]propane, 2,2bis[4methacryloxy(2hydroxypropoxyethoxy)phenyl]propane, and the like. These monomers can be used alone or in combination of two or more within the composition range. The proportion of these bifunctional acrylate or methacrylate monomers represented by the general formula in the coating composition must be in the range of 70 to 2% by weight, more preferably in the range of 60 to 4% by weight. .
If the usage ratio exceeds 70% by weight, the abrasion resistance of the cross-linked cured film decreases, and conversely, if the usage ratio is less than 2% by weight, the flexibility of the cross-linked cured film becomes poor and deformation strain is applied to the base material. This is undesirable because cracks sometimes occur in the cured coating and the adhesion to the substrate decreases. In the present invention, the surface of the synthetic resin molded product may be added to the coating composition, if necessary, within a range that satisfies these constitutional conditions and does not significantly reduce the air curability when irradiated with active energy rays in the air. The cross-linked cured film formed on the film has antistatic properties,
Other monomers may be used in combination for the purpose of imparting antifogging properties or other functions. The coating composition used in the present invention can be mixed with an organic solvent having specific properties depending on the necessity. When used in combination, organic solvents not only have extremely favorable effects on coating workability, uniform coating formation, and storage stability when coating a coating composition on the surface of a synthetic resin molded article. It also has the effect of increasing the adhesion of the crosslinked cured coating to the substrate. For example, a synthetic resin molded product with improved surface abrasion resistance by forming a crosslinked cured coating is subjected to a severe repeated test consisting of hot water immersion, cold water immersion, and high temperature drying. It has a great effect on changes in adhesion over time and durability.
This is surprising, and the reason for this is not clear, but due to the delicate interaction of the organic solvent with the base material and the polyfunctional monomer, a crosslinked cured film was formed that was uniform and had extremely excellent surface smoothness. It is presumed that one of the reasons for this is the synergistic effect between these two factors. In the conventional method of applying a polyfunctional acrylate or methacrylate monomer to the surface of a synthetic resin molded article or other object and irradiating it with active energy rays to form a crosslinked cured film, the crosslinking and curing reaction by polymerization is extremely fast. Therefore, using an organic solvent together with a polyfunctional acrylate or methacrylate monomer may cause the organic solvent to remain in the crosslinked cured film,
Since there is a strong possibility that the surface smoothness of the cured film will be impaired, studies have been progressing only in the direction of not using organic solvents. The inventors of the present invention have conducted detailed studies on this point in order to effectively take advantage of the advantages of coating workability when combined with organic solvents, and as a result, it has become possible to use organic solvents only when they satisfy the following requirements. In addition, it has been found that the above-mentioned crosslinked cured coating has an unexpected effect on the adhesion and durability. In other words, in the present invention, the organic solvent that can be used in combination with the coating composition has two properties: 1. It must be mixed with the coating composition to form a homogeneous solution. 2. It must have a boiling point of 50°C or more and 200°C or less at normal pressure. conditions must be met. First, it is natural and the most important condition to mix with the first coating composition to form a uniform solution. cannot be used because it does not form a homogeneous solution. Second boiling point at normal pressure
The conditions of 50°C or more and 200°C or less are necessary for forming a crosslinked cured film with excellent uniform film formation properties or surface smoothness when applied to the surface of a synthetic resin molded product. If the boiling point at normal pressure is less than 50°C, after the coating composition is applied, the surface of the substrate is cooled by the latent heat of the organic solvent that evaporates from the coating, and moisture in the air condenses there, causing the coating to form. In addition, if the temperature exceeds 200°C, the organic solvent evaporates from the coating film very slowly, resulting in workability problems, and the residual organic solvent may be removed during the active energy ray irradiation process. This is undesirable because the uniformity and surface smoothness of the cross-linked cured film may be lost due to the imbalance between the volatilization 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. . Therefore, the boiling point of the organic solvent used must be between 50°C and 200°C at normal pressure.
More preferably, it has a boiling point range of 60 to 150°C. The amount of the organic solvent to be mixed varies depending on the purpose of use, but is preferably in the range of 95 to 10 parts by weight (total 100 parts by weight) based on 5 to 90 parts by weight of the monomer mixture [A]. If it is less than 10 parts by weight, the effect will be small, and if it exceeds 95 parts by weight, it will be difficult to control the thickness of the crosslinked cured film and the abrasion resistance will be poor, which is not preferable. Organic solvents that can be used must satisfy the above conditions, and specifically include alcohols such as ethanol, isopropanol, normal propanol, isobutyl alcohol, and normal butyl alcohol, benzene, toluene, xylene,
Examples include aromatic hydrocarbons such as ethylbenzene, ketones such as acetone and methyl ethyl ketone, ethers such as dioxane, and acid esters such as ethyl acetate, n-propyl acetate, n-butyl acetate, and ethyl propionate. One of these organic solvents may be used alone, or a mixed solvent of two or more may be used as long as the boiling point and component ratio of the mixture meet the above requirements. . In addition, polymerizable monomers such as methyl acrylate, ethyl acrylate, methyl methacrylate, and styrene can be used as a type of organic solvent if they have a specific purpose, meet the same conditions, and have the same effects as organic solvents. It is also possible to do so. Depending on the type of synthetic resin that is used as the base material, these organic solvents may cause haze in those used for transparent purposes, may discolor the dyes and pigments in the colored base material, or may cause discoloration on the base material itself. Since cracks may easily occur, the type of organic solvent to be used must be appropriately selected depending on the type of substrate on which a crosslinked cured film is to be formed or the purpose. In the present invention, in order to apply the coating composition or the coating composition mixed with an organic solvent to the surface of the intended synthetic resin molded product and form a crosslinked cured film, it is necessary to apply active irradiation such as ultraviolet rays, electron beams, or radiation. It is necessary to irradiate it with energy rays. 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 photosensitizers include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether, acetoin, butyroin, toluoin, benzyl, benzophenone, p-chlorobenzophenone, p- - Carbonyl compounds such as methoxybenzophenone, sulfur compounds such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide, azo compounds such as azobisisobutyronitrile and 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 10 parts by weight per 100 parts by weight of the monomer compound [A] or monomer mixture [A] and organic solvent [B].
parts by weight, preferably in the range from 0.01 to 10 parts by weight. 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, and storage stabilizers may be appropriately added to the coating composition used in the present invention, if necessary. As the synthetic resin molded product used in the present invention, various synthetic resin molded products are used regardless of whether it is a thermoplastic resin or a thermosetting resin. Specific examples include polymethyl methacrylate resin, polycarbonate resin, and polyallyl diglycol carbonate. resin,
Examples include sheet-shaped molded products, film-shaped molded products, rod-shaped molded products, and various injection molded products manufactured from polystyrene resin, acrylonitrile-styrene copolymer resin, polyvinyl chloride resin, acetate resin, ABS resin, polyester resin, etc. It will be done. 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 optical properties, heat resistance, impact resistance, etc. These molded products are particularly preferred as synthetic resin molded products used in the present invention, since there is a strong demand for improved wear resistance. The various molded products used in the present invention can be used as they are, but if necessary, they can be cleaned and
Materials that have undergone pretreatment such as etching, corona discharge, active energy ray irradiation, dyeing, and printing can also be used. As a method for applying the above-mentioned coating composition to these synthetic resin molded articles, methods such as brush coating, flow coating, spray coating, spin coating, or dip coating are employed. 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 portion 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 more suitable. Spin coating is suitable for flat and symmetrical molded products, and dip coating is suitable for molded products that are rod-like or sheet-like. The amount of the coating composition to be applied to the surface of the synthetic resin molded article varies depending on the intended use of the obtained molded article or the content of monomers in the coating composition.
It is desirable that the coating be applied so that the thickness of the crosslinked cured film formed on the surface of the synthetic resin molded product is in the range of 1 to 30 μm. If the film thickness is less than 1μ, the wear resistance will be poor, and if it exceeds 30μ, the flexibility of the film will be impaired and cracks will easily occur in the film, which will reduce the strength of the molded product itself. This is not preferable as it may cause a decrease in As mentioned above, there are various methods for applying the coating composition, but among these methods, the dip coating method in particular has some limitations depending on the shape of the synthetic resin molded product, but the coating process is In addition to being simple and having excellent productivity, it also has the advantage that the thickness of the crosslinked cured film can be changed relatively freely. On the other hand, in order to make dip coating possible and to take advantage of its advantages, the following various conditions are required for the paint used. In other words, the following conditions are satisfied: the viscosity of the paint can be controlled relatively freely, it has excellent coating film formation properties through dip coating, the viscosity of the paint does not change over time, and it has excellent storage stability. It must be. The coating composition used in the present invention, especially the coating composition mixed with an organic solvent, satisfies these requirements,
and wear resistance, surface smoothness, flexibility, and durability.
It is a paint that has excellent adaptability to dip coating methods and can form a transparent crosslinked cured film with excellent water resistance, solvent resistance, and adhesion to substrates. Furthermore, depending on the use of synthetic resin molded products with a cross-linked cured film formed on the surface, extremely excellent surface smoothness may be required, or even after the cross-linked cured film has been formed, it may be necessary to It is required to withstand severe conditions such as bending, machining such as cutting and drilling, and the application of large deformation strains during parts installation or use. In such cases, it is naturally necessary that the crosslinked cured film itself has excellent properties such as flexibility and adhesion to the base resin, but the second factor is the problem of the thickness of the cured film. . That is, the thinner the film, the more resistant it is to these external effects, but on the other hand, if it becomes extremely thin, the abrasion resistance decreases, so the thickness of the crosslinked cured film is preferably in the range of 1 to 9 microns. At the technical level of using conventional polyfunctional acrylate or methacrylate monomers or mixtures thereof as cross-linked cured film forming materials, it has excellent abrasion resistance, surface smoothness, film thickness uniformity, transparency, and film appearance. However, it has been impossible to form such a thin crosslinked cured film on the surface of a synthetic resin molded product. However, among the coating compositions mixed with organic solvents used in the present invention, a coating composition prepared such that the viscosity at 25°C is 10 centipoise or less is applied to the surface of a synthetic resin molded article by dip coating. By cross-linking and curing, a thin transparent cross-linked cured film in the range of 1 to 9 μm is formed which has excellent wear resistance, surface smoothness, film thickness uniformity, film appearance, and adhesion to the substrate. became possible.
This is one of the important points of the present invention. Next, the synthetic resin molded product, which is coated using a method suitable for the shape of the synthetic resin molded product or its required performance, is crosslinked and cured by irradiation with active energy rays.
When using a coating composition containing an organic solvent as a coating, it is placed under specific conditions before being irradiated with active energy rays to form a crosslinked cured film.
After evaporating more than 50% by weight of the organic solvent contained in the coating applied to the surface of the synthetic resin molded product,
It is better to irradiate with active energy rays. If the applied film contains 50% by weight or more of an organic solvent and is irradiated with active energy rays, depending on the type of organic solvent, the surface smoothness of the crosslinked cured film formed may be impaired or the film may be damaged. Unfavorable phenomena such as generation of bubbles or residual organic solvent in the crosslinked cured film may occur, such as whitening of the film. In order to form a cross-linked cured film, ultraviolet rays emitted from a light source such as a xenon lamp, low pressure mercury lamp, medium pressure mercury lamp, high pressure mercury lamp or ultra-high pressure mercury lamp, or an electron beam extracted from an electron beam accelerator of usually 20 to 2000 KV, alpha rays, The applied film must be crosslinked and cured by irradiating active energy rays such as β rays and γ rays. From the point of view of practicality or workability, ultraviolet light is the most preferable irradiation source. Although 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, the coating composition used in the present invention can be irradiated with an ordinary air atmosphere. However, it is possible to form a crosslinked cured film with excellent wear resistance and other properties. 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. A synthetic resin molded article having a crosslinked cured coating on its surface produced by the method of the present invention has excellent surface smoothness and aesthetic appearance, and has extremely excellent surface hardness, abrasion resistance, and scratch resistance. 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 and does not cause peeling or cracking even under harsh conditions or environments. It is extremely useful for applications such as organic window glass, lighting equipment covers, reflectors, mirrors, eyeglass lenses, sunglass lenses, optical lenses, and watch 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 according to JISK5651-1966 b Scratch test... Scratch test with #000 steel wool 〇... There is almost no scratch on the surface even if lightly rubbed △... Lightly If rubbed, the surface will be slightly scratched. ×... Even if rubbed lightly, the surface will be severely scratched (same level as the base resin) (2) Adhesion Cross-cut cellotape peel test on cross-linked cured film. That is, make 100 1 mm ² cuts by inserting 11 film cutting lines vertically and horizontally into the film that reach the base material at 1 mm intervals, then stick cellophane tape on top of it and peel it off rapidly. Repeat this cellotape operation three times at the same location. 〇……No peeling marks of the cross-linked cured film even after repeating 3 times △……Number of peeling marks after repeating 3 times 1 to 50 ×……Number of peeling marks after repeating 3 times 51 to 100
(3) Flexibility (maximum bending angle) A cross-linked cured film is formed on the surface of a sheet-like molded product with a thickness of 2 to 3 mm, and a strip-shaped test piece with a width of 6 mm and a length of 5 cm is cut out from this. Apply force from both ends to give a bending deformation strain, and find the angle from the horizontal plane of the specimen when a crack occurs in the coating. This is the "maximum bending angle", and the larger this angle, the better the flexibility of the coating. (4) Thermal and cycle tests Molded products with a cross-linked cured film formed on the surface were heated at 65°C.
After soaking in warm water for 1 hour, immediately put it in ice water at 0℃.
Soak for 10 minutes, then dry with hot air at 80℃ for 1 hour. After repeating this several times, various tests are performed. Example 1 A disc-shaped methacrylic resin injection molded product with a thickness of 2 mm and a diameter of 4 cm was pasted on a rotating plate in a quartz cylinder equipped with a rotation drive body so that the center of the molded product was centered on the rotating shaft. The temperature inside the cylinder was maintained at 40℃. Approximately 1.0 g of the coating composition shown in Table 1 is poured onto the center of the upper surface of this cylindrical molded product, and the rotating plate is immediately rotated at a speed of 3000 revolutions per minute to form a coating film on the upper surface of the molded product. I let it happen. Next, the rotation speed was reduced to 5 rotations/minute, and the quartz cylinder was rotated slowly from above diagonally outside the quartz cylinder in an air atmosphere.
A 100W high-pressure mercury lamp (manufactured by Ushio Inc.) was irradiated for 10 minutes to form a crosslinked cured film on the upper surface of the molded product. Table 1 shows the evaluation results for the molded products obtained. The coating compositions shown in Table 1 are all 2.0
Contains parts by weight of benzoin isobutyl ether.

【table】

[Table] As is clear from the results, the molded product obtained by the present invention (Experiment No. 1) has a crosslinked cured film with excellent surface smoothness, abrasion resistance, and adhesion. Paints using paint compositions other than those of the invention had poor adhesion (Experiment No. 2);
The abrasion resistance may be poor (Experiment No. 3) or the crosslinking curing reaction may not proceed sufficiently (Experiment No. 4).
and 5) a molded article with balanced performance cannot be obtained. Example 2 Dipentaerythritol pentaacrylate 90
10 parts by weight of 2,2-bis(4-acryloxydiethoxyphenyl)propane and 2 parts by weight of penzoin ethyl ether were stirred and mixed, and the resulting coating composition was applied to a methacrylic resin cast molded plate with a thickness of 2 mm. A cross-linked cured film was uniformly coated on one side of the film using a bar coater so that the film thickness was as shown in Table 2. This was irradiated with a 2 kW high-pressure mercury lamp for 15 seconds in an air atmosphere from a distance of approximately 30 cm from the coating surface to form a transparent crosslinked cured coating on the surface of the molded product. The results obtained are shown in Table 2.

[Table] As can be seen from this result, as the thickness of the cross-linked cured film increases to 35 μm, the flexibility and adhesion of the cured film deteriorates, and the impact strength of the molded product also decreases. Incidentally, the impact strength was measured in accordance with BS-1330 by cutting out a 1 cm x 2 cm test piece from the obtained molded product and applying an impact from the side having the cured film. Example 3 Dipentaerythritol pentaacrylate 70
parts by weight, 5 parts by weight of pentaerythritol trimethacrylate, 25 parts by weight of 2,2-bis(4-acryloxypropoxyphenyl)propane, 0.5 parts by weight of benzoin isobutyl ether, 0.5 parts by weight of benzoin ethyl ether, and 1.0 parts by weight of benzophenone at 60°C. The coating composition obtained by stirring and mixing under heating of It was applied so that the thickness was 12μ. This was irradiated with ultraviolet rays in exactly the same manner as in Example 2 to form a crosslinked cured film on the surface of each molded product. Each molded article had excellent surface gloss, and had good abrasion resistance and adhesion. The evaluation results are shown in Table 3.

[Table] Example 4 Dipentaerythritol pentaacrylate 25
Parts by weight, pentaerythritol triacrylate
A coating composition consisting of 25 parts by weight, 50 parts by weight of 2,2-bis(4-acryloxyethoxyphenyl)propane, and 2 parts by weight of benzoin isobutyl ether was applied to the surface of a plastic denture made of dental methacrylic resin. It was applied with a brush to a thickness of 14 to 16 μm. After fixing this to a rotating shaft inside a quartz cylinder equipped with a rotary drive body, this rotating shaft was rotated at a speed of 5 revolutions per minute, and while air was circulating inside the cylinder, 300 W of far infrared rays was applied for 2 minutes. 100W high pressure mercury lamp
The quartz cylinder was irradiated from diagonally above the outside to form a cross-linked hardened film on the surface of the plastic denture. The molded product obtained was excellent in the steel wool abrasion test and the adhesion of the cured film. Example 5 Dipentaerythritol pentaacrylate
360 parts by weight of 22bis(4-acryloxydiethoxyphenyl)propane and 20 parts by weight of benzoin ethyl ether were mixed and stirred at 60°C to obtain a monomer mixture. This monomer mixture was mixed with an organic solvent containing 340 parts by weight of isopropyl alcohol and 60 parts by weight of xylene in the proportions shown in Table 4 to obtain a uniform coating composition. A cast molded plate made of methacrylic resin having a thickness of 3 mm was immersed in these coating compositions, and then slowly pulled up at a speed of 0.5 cm/sec to form a coating film of the coating composition on the surface of the molded plate. After leaving it at a room temperature of 25°C for 30 minutes, it was attached to a drive body that could transport it into a high-power opposing ultraviolet irradiation box with two 2 kW high-pressure mercury lamps facing each other and air circulating through it. Next, the ultraviolet irradiation time in the box was set to 15 seconds, and the driver was moved to pass through the irradiation box to form a crosslinked cured film on the surface of the molded plate. Table 4 shows the results of evaluating the performance of the obtained molded products.

[Table] As is clear from the results, the dip coating method allows relatively easy control of the thickness of the crosslinked cured film by adjusting the viscosity of the coating composition, and also has excellent surface smoothness and uniformity. In particular, when the viscosity of the coating composition at 25° C. is 10 centipoise or less, the film thickness is thin and has excellent uniformity, as well as excellent flexibility. Furthermore, as is clear from a comparison between Experiment No. 1 of Example 2 and Experiment No. 7 of Table 4, the constituent components of the cross-linked cured film are exactly the same and the film thickness is approximately the same, but the adhesion after thermal cycling is There is a difference in the properties and advantages of using an organic solvent are recognized. The product of the present invention shows excellent performance, but when the thickness of the cross-linked cured film is extremely thin as in Example 5 Experiment No. 9, the film has excellent flexibility and adhesion but deteriorates abrasion resistance. do. Example 6 Dipentaerythritol pentaacrylate 40
parts by weight, 40 parts by weight of pentaerythritol tetraacrylate, 12 parts by weight of pentaerythritol triacrylate, 8 parts by weight of 2,2-bis(4-acryloxypropoxyphenyl)propane, 4 parts by weight of benzoin ethyl ether, and as shown in Table 5. A uniform coating composition was obtained by adding and mixing 300 parts by weight of various types of organic solvents. A cast molded plate made of methacrylic resin having a thickness of 2 mm was immersed in these compositions and slowly pulled up to form a coating film on the surface of the molded plate. After leaving this for 10 minutes in a box that circulated hot air at 40°C, it was heated for 15 minutes using the same high-output opposite ultraviolet irradiation device as used in Example 5.
A crosslinked cured film was formed on the surface of the molded article by irradiating it with ultraviolet rays for seconds. Various performances of the obtained molded product were measured and the evaluation results are shown in Table 5. As is clear from the results in Table 5, when organic solvents other than those used in the present invention are used, the coating film forming properties, the adhesion of the cured film, or the appearance of the crosslinked cured film may be deteriorated.

[Table] * Boiling point example of main solvent alcohol 7 Dipentaerythritol hexaacrylate 10
parts by weight, 20 parts by weight of dipentaerythritol pentaacrylate, 10 parts by weight of pentaerythritol tetramethacrylate, 10 parts by weight of 2,2-bis(4-methacryloxyethoxyphenyl)propane, 40 parts by weight of isopropyl alcohol, and 10 parts by weight of toluene. to make a homogeneous solution. Furthermore, benzoin isobutyl ether 0.4 is added as a photosensitizer to this.
A coating composition was obtained by dissolving a sensitizer mixture consisting of 0.4 parts by weight of benzoin ethyl ether and 1.2 parts by weight of benzophenone. This was spray coated on the outer surface of a conical methacrylic resin injection molded product with a thickness of 3 mm, a radius of 6 cm, and a height of 5 cm to form a film having an average thickness of about 20 μm. After leaving this at room temperature of 25℃ for 30 minutes,
2kw from a distance of approximately 30cm from the covered surface in an air atmosphere
A cross-linked cured film with an average thickness of 11 μm was formed on the outer surface of the molded product by irradiating it with light from a high-pressure mercury lamp for 20 seconds. The abrasion resistance of the outer surface of the molded product is measured by pencil hardness.
It also had excellent performance in the 8H and steel wool abrasion tests. In addition, the adhesion of the cured film showed no peeling in the cross-cut Sellotape test, and no change was observed even after 5 thermal cycle tests. Example 8 Dipentaerythritol pentaacrylate 20
Parts by weight, 10 parts by weight of 2,2-bis(4-acryloxyethoxyphenyl)propane, 2,2-bis[4-
(2-hydroxy-3-acryloxypropoxy)phenyl] Polycarbonate plate-shaped molded product with a thickness of 2 mm coated with a coating composition consisting of 10 parts by weight of propane, 55 parts by weight of n-butyl alcohol, 15 parts by weight of toluene, and 1.5 parts by weight of benzoin isobutyl ether. was immersed to form a coating film. This was done in exactly the same manner as in Example 5, and a crosslinked cured film was formed on the surface of the molded product by irradiating it with a light source from a high-pressure mercury lamp. The surface of the obtained molded article was extremely smooth, and the thickness of the cured film was 5.0 μm. The pencil hardness of the surface was 6H, and the adhesion of the coating did not peel off in the cross-cut Sellotape test, and no change was observed in the abrasion resistance or adhesion of the coating even after the thermal cycle test was repeated five times. Example 9 10 parts by weight of pentaerythritol tetraacrylate, 10 parts by weight of pentaerythritol triacrylate
Parts by weight, 4 parts by weight of 2,2-bis(4-acryloxyethoxyphenyl)propane, 1 part by weight of 2,2-bis(4-acryloxyphenyl)propane, 55 parts by weight of n-butyl alcohol, 15 parts by weight of xylene, and benzoin. A polyallyl diglycol carbonate lens (CR-39 lens) was immersed in a coating composition containing 1.5 parts by weight of isobutyl ether and slowly pulled up to form a coating film on the surface of the lens. This was placed in a quartz cylinder through which hot air at 40°C was circulated, and after being held for 3 minutes, both sides of the molded product were irradiated with light from a 100W high-pressure mercury lamp for 10 minutes from a distance of 20cm from the surface of the molded product. At this time, for the first two minutes, 300 W of far infrared rays and ultraviolet rays were simultaneously irradiated from both sides of the quartz cylinder diagonally above. The surface of the molded product obtained is extremely smooth, and the thickness of the cured film is
It was 5.2μ. In addition, the pencil hardness of the surface was 8H and the steel wool abrasion test was excellent, and the adhesion of the cured film showed no peeling in the cross-cut Sellotape test. Example 10 Dipentaerythritol pentaacrylate 5
Parts by weight, 10 parts by weight of pentaerythritol tetraacrylate, 10 parts by weight of pentaerythritol triacrylate, 5 parts by weight of 2,2-bis(4-methacroxypropoxyphenyl)propane, 2 parts by weight of benzoin isobutyl ether, and methyl methacrylate/isopropyl alcohol/ Toluene = 40/
A uniform coating composition was obtained by mixing 70 parts by weight of a mixed solvent of 40/20% by weight. A methacrylic resin cast molded plate with a thickness of 4 mm was immersed in this and slowly pulled up to form a coating film on the surface of the molded product. A curing treatment was carried out in exactly the same manner as in Example 5 to obtain a molded article having a crosslinked cured film with a thickness of 5.5 μm. The surface appearance of the molded product is extremely good, and the pencil hardness is also low.
8H, and was also excellent in the steel wool abrasion test and film adhesion, and no change in abrasion resistance or film adhesion was observed even after the thermal cycle test was repeated 5 times. Example 11 Dipentaerythritol pentaacrylate 60
Parts by weight, 15 parts by weight of pentaerythritol tetraacrylate, 10 parts by weight of 2,2-bis(4-acryloxyethoxyphenyl)propane, 10 parts by weight of toluene, 5 parts by weight of ethanol and 2 parts by weight of benzoin isobutyl ether were mixed to form a homogeneous mixture. A coating composition was obtained. In exactly the same manner as in Example 1, this was spin-coated onto a disk-shaped methacrylic resin injection molded plate with a thickness of 2 mm and a diameter of 4 cm, and then ultraviolet rays were irradiated to form a film on one side.
A cross-linked cured film of 13μ was formed. The surface appearance of the molded product was good, the pencil hardness was 8H, and the steel wool abrasion test and film adhesion were excellent, and no change in abrasion resistance or adhesion was observed even after 5 thermal cycle tests. Example 12 Dipentaerythritol hexaacrylate 30
Parts by weight, 30 parts by weight of dipentaerythritol pentaacrylate, 30 parts by weight of dipentaerythritol tetraacrylate, 10 parts by weight of 2,2-bis(4-acryloxypentaethoxyphenyl)propane,
Isopropyl alcohol 150 parts by weight, toluene 150 parts
2 parts by weight of benzoin ethyl ether and 2 parts by weight of benzophenone, a methacrylic resin cast molded plate with a thickness of 2 mm is immersed,
The molded plate was 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 this was left for 5 minutes, ultraviolet rays were irradiated for 10 seconds using the same irradiation device used in Example 5 to form a crosslinked cured film with a thickness of 4 μm on the surface of the molded product. The surface of the molded product obtained was excellent in smoothness, with a pencil hardness of 7H, and was also excellent in the Stale abrasion test and film adhesion.Even after repeated thermal cycle tests 5 times, there were no changes in abrasion resistance and film adhesion. was not recognized.

Claims (1)

[Claims] 1. Pentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, dipentaerythritol triacrylate, dipentaerythritol trimethacrylate, dipentaerythritol tetraacrylate, dipentaerythritol tetramethacrylate , 30 to 98% by weight of at least one polyfunctional monomer selected from the group consisting of dipentaerythritol pentaacrylate, dipentaerythritol pentamethacrylate, dipentaerythritol hexaacrylate, and dipentaerythritol hexamethacrylate, and the following general formula: (In the formula, R ₁ is hydrogen or a methyl group, n is 0 or an integer from 1 to 5, and X is an alkylene group having 6 or less carbon atoms, or one hydrogen atom of the alkylene group is substituted with a hydroxyl group. (These may be the same or different when n is 2 or more.)
100 parts by weight of a monomer mixture [A] consisting of 70 to 2% by weight of a bifunctional monomer represented by: and 0 to 10 parts by weight of a photosensitizer.
parts by weight, which can form a crosslinked cured film with excellent wear resistance when irradiated with active energy rays in air, is applied to the surface of a synthetic resin molded product, and then irradiated with active energy rays. 1. A method for producing a wear-resistant synthetic resin molded article, which comprises forming a cross-linked cured film with a thickness of 1 to 30 μm. 2. The amount of photosensitizer added is 0.01 to 10 parts by weight,
2. The method for producing a wear-resistant synthetic resin molded article according to claim 1, wherein the active energy ray is an ultraviolet ray. 3. The method for producing a wear-resistant synthetic resin molded article according to claim 1, wherein the synthetic resin molded article is a methacrylic resin, polycarbonate resin, or polyallyl diglycol carbonate resin molded article. 4 Pentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, dipentaerythritol triacrylate, dipentaerythritol trimethacrylate, dipentaerythritol tetraacrylate, dipentaerythritol tetramethacrylate, dipentaerythritol penta acrylate, dipentaerythritol pentamethacrylate, dipentaerythritol hexaacrylate, and dipentaerythritol hexamethacrylate in an amount of 30 to 98% by weight of at least one polyfunctional monomer and the following general formula: (In the formula, R ₁ is hydrogen or a methyl group, n is 0 or an integer from 1 to 5, and X is an alkylene group having 6 or less carbon atoms, or one hydrogen atom of the alkylene group is substituted with a hydroxyl group. (These may be the same or different when n is 2 or more.)
100 parts by weight of a monomer mixture [A] consisting of 70 to 2% by weight of a bifunctional monomer represented by: and 95 to 10 parts by weight of at least one organic solvent [B] which is mixed with this to form a homogeneous solution. 0 to 10 parts by weight of photosensitizer (total of 100 parts by weight of the monomer mixture [A] and organic solvent [B]), and has wear resistance by irradiation with active energy rays in air. After coating the surface of a synthetic resin molded product with a coating composition capable of forming a crosslinked cured film with excellent properties, active energy rays are irradiated to form a crosslinked cured film with a thickness of 1 to 30 μm on the surface of the synthetic resin molded product. 1. A method for producing a wear-resistant synthetic resin molded product, which comprises forming a wear-resistant synthetic resin molded product. 5. The method for producing a wear-resistant synthetic resin molded article according to claim 4, wherein the organic solvent has a boiling point of 50°C or more and 200°C or less at normal pressure. 6 The amount of photosensitizer added is 0.01 to 10 parts by weight,
5. The method for producing a wear-resistant synthetic resin molded article according to claim 4, wherein the active energy ray is an ultraviolet ray. 7 The coating composition is applied to the surface of the synthetic resin, and after evaporating and evaporating 50% or more of the organic solvent contained in the applied film, active energy rays are irradiated to form a film thickness of 1 on the surface of the synthetic resin molded product. Claim 4, characterized in that a crosslinked film of ~30μ is formed.
A method for manufacturing a wear-resistant synthetic resin molded product as described in . 8. The coating composition has a viscosity of 10 centipoise or less at 25°C, and when applied to the surface of a synthetic resin molded product by dip coating, the thickness of the crosslinked cured film is 1 to 9 μm. A method for manufacturing a wear-resistant synthetic resin molded article according to claim 4 or 7, characterized in that: 9. A method for manufacturing a wear-resistant synthetic resin molded article according to claim 4, 7, or 8, characterized in that the synthetic resin molded article is a methacrylic resin, polycarbonate resin, or polyallyl diglycol carbonate resin molded article. .