JPS60173023A - Production of synthetic resin molding excellent in abrasion resistance and surface smoothness - Google Patents

Abstract

PURPOSE:To obtain a resin molding excellent in abrasion resistance and surface smoothness, by coating the surface of a synthetic resin molding with a coating composition containing a specified component and irradiating the molding in air with actinic energy rays. CONSTITUTION:The titled molding is produced by coating the surface of a synthetic resin molding with a coating composition comprising 5-90pts.wt. (A) monomer mixture comprising 30-90pts.wt. polyfunctional monomer of a mono- or poly-pentaerythritol poly(meth)acrylate of formula I (wherein n is 0-4, at least three X's are groups of formula II, and the rest are OH groups, R is H or CH3), 0-40pts.wt. bifunctional monomer of formula III (wherein R1 is H or CH3, n is 0-5, and Y is a 6C or lower alkylene or the like), and 5-70pts.wt. monomer having at least two groups of formula II, and having an atmospheric b.p. >=150 deg.C and a viscosity at 20 deg.C <=20cP, 95-10pts.wt. (B) organic solvent, and 0- 10pts.wt. (per 100pts.wt. total of components A and B) (C) photosensitizer and irradiating the molding in air with actinic energy rays to form a crosslinked cured coating of a film thickness of 1-30mu on the surface of the molding.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is based on active energy ray irradiation in an air atmosphere.
Abrasion resistance and surface smoothness are achieved using a coating composition that can form a crosslinked cured film with excellent abrasion resistance, surface smoothness, flexibility, heat resistance, solvent resistance, durability, and adhesion to the substrate. The present invention relates to a method for producing synthetic resin molded products with excellent properties.

Polymethyl methacrylate resin, polycarbonate resin, polyallyl diglycol carbonate resin, polystyrene resin, sterene-acryloni) IJ copolymer resin (AS resin), polyvinyl chloride resin, acetate resin,
Acrylonitrile-butadiene-styrene copolymer resin (
Synthetic resin molded products made from ABS resin), polyester resin, etc. are not only lighter and have better impact resistance than glass products, but also have various advantages such as being cheaper and easier to mold. Optical applications such as glass, organic plate glass, lighting equipment covers, optical lenses, eyeglass lenses, reflectors, mirrors, decorative applications such as signboards and displays, name plates, dust cover cases, automobile parts, etc. Development of its applications is progressing in many fields.

However, these synthetic resin molded products lack surface abrasion resistance, so the surface may be damaged by contact with other objects, scratches, etc. during transport, installation, or use of the molded product. damaged and reduced product yield,
The aesthetic appearance has been ruined. In particular, molded products are used for cameras, optical lenses such as magnifying glasses, fashion glasses,
In the case of eyeglass lenses such as sunglasses, corrective lenses, window glass, decorative cases, covers, watch lenses, reflectors, mirrors, etc., damage that occurs to the surface of the product significantly reduces its commercial value. However, since it becomes unusable in a short period of time, there is a strong demand for improving the abrasion resistance of the surface.

Methods to improve these drawbacks of synthetic resin molded products have been studied many times in the past. There is a method in which a methacrylate monomer is applied as a crosslinked cured coating onto 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 is imbued with polymerization activity when irradiated with active energy rays, so it has been used as a quick-drying ink material in US Patent No. 3.661
．． No. 614, No. 3.551.311, No. 3.55
1.246 or British Patent No. 1.198.259
The application of these polyfunctional (meth)acrylate monomers as a surface modification material for synthetic resin molded articles is proposed in U.S. Pat. No. 6,552,98.
No. 6, No. 2.415.973, or No. 5.7 of the same
This is proposed in the specification of No. 70.490.

On the other hand, the present applicants have also discovered that polyfunctional (meth)acrylate monomers have excellent cross-linking and curing polymerizability upon irradiation with active energy rays, and that they can improve the abrasion resistance of the surface of synthetic resin molded products. We discovered that it was effective as a material for forming cross-linked cured films and made many proposals (Special Publication Publication No. 48-4
No. 2211, No. 49-12886, No. 49-2295
No. 1, No. 49-14859, No. 49-22952).

A method in which these polyfunctional (meth)acrylate monomers are applied as a cross-curing paint to the surface of a synthetic resin molded product, and active energy rays are irradiated to form a cross-cured film on the surface of the synthetic resin molded product. 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 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 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, inert gas such as nitrogen gas, nitrogen gas, carbon dioxide gas, etc. If the crosslinking and curing reaction is not carried out under an ambient atmosphere, the crosslinking and curing reaction will be inhibited by oxygen in the air, and a crosslinked and cured film having sufficient wear resistance will not be formed. This is an extremely serious problem in practical terms. Not only does it complicate the process, but it also makes it difficult to maintain a constant low oxygen concentration in the surrounding air, resulting in inconsistent performance and reduced product yield. This can also cause an increase in costs.

The second point is that many polyfunctional (meth)acrylate monomers have a high viscosity at room temperature, and the more effective they are for improving abrasion resistance, the higher the viscosity, resulting in poor coating workability and poor paint quality. In addition to being limited in the application method, there are also operational problems such as insufficient surface smoothness of the cross-linked cured film, difficulty in controlling the film thickness, and other problems such as poor adhesion to the substrate, etc. It is extremely difficult to form a thin crosslinked cured film with excellent wear resistance, surface smoothness, and 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. There are still many issues that need to be addressed,
Despite its 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 as a result, they have developed a paint composition containing specific components in specific proportions, which is then applied to the surface of a synthetic resin molded product to achieve specific results. The present invention was completed by discovering that the above-mentioned drawbacks could be solved at once by forming a crosslinked cured film having a specific thickness range by irradiating active energy rays under the following conditions.

That is, the present invention is based on the following general formula (where n is 0 or an integer of 1 to 4, at least 3 of X are CH2=CR-Coo- groups, and the remaining 9 are 10H groups. R is Represents hydrogen or methyl group.) Polyfunctional monomer of tall poly(meth)acrylate (a) 60-95
parts by weight and the following general formula 0 0H30 (in the formula, 8 is hydrogen or methyl group D, n is 0 or 1-
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 Y's may be the same or different when n is 2 or more. ] Bifunctional monomer (
b) A monomer having 0 to 60 parts by weight and 2 or less (meth)acryloyloxy groups in one molecule, a boiling point of 150°C or higher at normal pressure, and a viscosity of 20 cmV or less at 20°C. (c) a monomer mixture consisting of 5 to 70 parts by weight)
(Total 100 parts by weight) 5-90 parts by weight of the monomer mixture), at least 1 tsp of organic solvent (Q3) mixed with the monomer mixture to form a homogeneous solution, 95-10 parts by weight of the photosensitizer (c) )0
~10 parts by weight (to the monomer mixture) and an organic solvent (J3
)] is applied to the surface of the synthetic resin molded product, and then irradiated with active energy rays in the air to give a film thickness of 1% on the surface of the synthetic resin molded product.
The present invention relates to a method for producing a synthetic resin molded article with excellent wear resistance and surface smoothness, which is characterized by forming a crosslinked cured coating of ~30 μm.

The greatest feature of the present invention is that a specific trifunctional or higher (meth)acrylate monomer, a specific bifunctional (meth)acrylate monomer, and a specific bifunctional or less (meth)acrylate monomer are combined with organic Abrasion resistance, surface smoothness, flexibility, water resistance, heat resistance, wear resistance, and adhesion to substrates are achieved by blending a solvent into a specific formulation and irradiating it with active energy rays in an air atmosphere. By using a coating composition that can form a transparent crosslinked cured coating with excellent properties, a synthetic resin molded article with excellent abrasion resistance and surface smoothness can be obtained.

General formula used in the present invention (where n is 0 or an integer of 1 to 4, at least 5 of X are C'H, =OR-Coo- groups, and the remainder is -01 (group). R represents hydrogen or a methyl group.) The polyfunctional monomer (a) of polypenotaerythritol poly(meth)acrylate represented by (a) has very good polymerization activity when irradiated with active energy rice grains. 9, it is also cross-linked and cured to form a highly cross-linked cured polymer that exhibits high wear resistance.In the present invention, the polyfunctional monomer (L3) represented by the above general formula (1) is used. ), the purpose can be fully achieved by using pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, etc. ) acrylate, dipentaerythritol hexa(meth)acrylate, etc. are particularly preferred in terms of polymerization activity by irradiation with active energy rays in air and ease of handling based on low viscosity. The polyfunctional monomer (-) may be used alone or in combination of two or more.

The proportion of polyfunctional monomer (a) used is as follows: monomer mixture (A)
30-95 parts by weight in 100 parts by weight, preferably 35-94 parts by weight
Parts by weight. If the amount of polyfunctional monomer (a) is less than 30 parts by weight in the monomer mixture, a cured film with sufficient wear resistance cannot be obtained, and if the amount exceeds 95 parts by weight. This is not preferred because the smoothness of the film is poor.

In addition, in the present invention, even if the polyfunctional monomer has six or more (meth)acryloyloxy groups in one molecule, a polyfunctional monomer that does not satisfy the general formula (I), such as 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 it cannot perform sufficient crosslinking and curing.

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, it is a monomer that imparts air curability and is a bifunctional (meth)acrylate monomer represented by the following general formula.

Q CHs O (in the formula, Mr. is hydrogen or a methyl group, n is 0 or 1-
is an integer of 5, and Y is an alkylene group with 6 or less carbon atoms, or an alkylene group in which one hydrogen atom is replaced with a hydroxyl group.0 These Ys are the same or different when n is 2 or more. ).

Also in the compound represented by this general formula, the number of carbon atoms in Y is 7
If the number n is 6 or more, it is not preferable because the abrasion resistance of the crosslinked cured film is poor or the adhesion to the substrate is reduced. A particularly preferred monomer is one in which the number of carbon atoms in tL Y is 3 or less and the number of n is 5 or less.

Specific examples of the bifunctional monomer (b) represented by the above general formula include 2.2-bis(4-acryloxyphenyl)propane, 2.2-bis(4-methacryloxyphenyl)propane, 2.2-bis(4-7ri')oxyethoxyphenyl)propane, 2.2-bis(4-methacryloxyethoxyphenyl)propa7.2.2-bis(
4-acryloxyjethoxyphenyl)propane, 2.
2-bis(4-methacryloxyjethoxyphenyl)propane, 2,2-bis(4-acryloxypropoxyphenyl)propane, 2,2-bis(4-methacryloxyethoxyphenyl)propane, 2.2-bis[ 4-acryloxy(2-hydroxypropoxy)phenyl]propane, 2,2-bis[4-methacryloxy(2-hydroxygloboxinphenyl)]propane, 2,2-bis[
4-acryloxy(2-hydroxyproboxyethoxy)phenyl]propane, 2,2-bis[4-methacryloxy(2-hydroxygloboxyethoxy)phenyl]
Examples include fropan.

These monomers can be used alone or in combination of two or more within the composition range.

These bifunctional monomers (1) represented by general formula (II)
The proportion used is 0 to 60 in 100 parts by weight of the monomer mixture.
Parts by weight. If the amount of the difunctional monomer (a) exceeds 60 parts by weight in the monomer mixture, the abrasion resistance of the crosslinked cured coating will be lower than 1, which is not preferred.

In addition, it has two or less 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 centimeters at 20°C. The following monomer (C) [hereinafter simply referred to as monomer (C')] is used to create a very smooth surface called a mirror surface after coating a molded product with a coating composition. It is necessary to give the cured film flexibility and adhesion to the base material.In other words, after the coating composition of the present invention is applied to a molded article, a coated film with extremely excellent smoothness is formed. In order to achieve this, it is desirable that the viscosity of the monomer mixture () be 1000 centivoise or less, and that the cured film after curing should have similar smoothness, flexibility, and adhesion to the substrate. Therefore, a monomer (
It is necessary to use C) together. Specific examples of this monomer (C) include neobentyl glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate. Ethylene glycol dimethacrylate, t3-butylene di(meth)acrylate, t4-butanediol di(meth)acrylate), 1,6-hexanethiol di(meth)acrylate, 1゜3-globylene glycol di(meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)azilylate, tridecyl (meth)acrylate
Acrylate, cyclohexyl (meth)acrylate,
2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, benzyl (meth)acrylate, 1.4-
Butylene glycol mono(meth)acrylate, ethoxyethyl(meth)acrylate, ethelcarpitol (
meth]acrylate, 2-hydroxy-6-chlorogelovir (meth)acrylate, diglopyrene glycol di(meth)acrylate, and the like.

Among these monomers, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol dimethacrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, and 2-hydroxypropyl(meth)acrylate are used in the present invention. ) acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, ethoxyethyl (meth)acrylate, ethylcarpitol (meth)acrylate, butoxyethyl (meth)acrylate, 1,4
-Hydroxy group and/or cyclic ether bond and/or between monomer side chains or two (meth)acryloyloxy groups such as butylene glycol mono(meth)acrylate, diglobylene glycol di(meth)acrylate, etc.
Alternatively, monomers having all chain ether bonds are particularly preferred since they have excellent polymerization activity in open air. These monomers (C) can be used alone or in combination of two or more within the composition range.

The proportion of monomer (C) used is 10 of the monomer mixture (g).

5 to 70]i 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, if the monomer (C) exceeds 70 parts by weight, it is not preferable because a crosslinked cured coating having sufficient wear resistance cannot be obtained. Furthermore, the boiling point of monomer (C) is 1 at normal pressure.
If the temperature is lower than 50°C, when the coating composition is applied to the surface of the molded product and cured, it will volatilize and escape, resulting in an increase in the viscosity of the coating composition, and the viscosity of the monomer (C') will be lower than 20°C. 20 in
If it exceeds centipoise, it is not preferable because the viscosity of the monomer mixture cannot be effectively lowered.

The above are the essential constituents of the single-temperature mixture (g) that constitutes all of the components of the coating composition used in the present invention, but if necessary, within the range where these constituent conditions are satisfied, Other monofunctional vinyl systems that can be copolymerized with these monomer mixtures and have polymerization activity with active energy rays for the purpose of imparting antistatic properties, antifogging properties, or other functions to the crosslinked cured film formed. At least one type of monomer may be used in combination.

The organic solvent () used in combination with the monomer mixture constituting the coating composition used in the present invention () is the coating workability when coating the coating composition on the surface of a synthetic resin molded article;
It is used to impart extremely favorable effects on the ability to form a uniform coated film or on storage deformation properties, and to dramatically increase the adhesion of a crosslinked cured film to a substrate.

In the present invention, the organic storage agent used is 1) mixed with a polyfunctional (meth-acrylate monomer mixture (A)) to form a homogeneous solution.

2) The boiling point at normal pressure is 50°C or more and 200°C or less.

The viscosity at room temperature is 10 centipoise or less.

4) Polyfunctional (methocacrylate monomer mixture)
It is used at a ratio of 95 to 10]i lid parts to 90 parts by weight (total 100 parts by weight).

It is necessary to satisfy the following conditions. First of all, multi-sensual (meta)
The first condition is to form a homogeneous solution with the acrylate monomer mixture. For example, saturated hydrocarbon-based organic solvents such as n-hexane, n-hebutane, and cyclohexane do not form a uniform solution. I can not use it. The second condition of boiling point at normal pressure of 50°C or more and 200°C or less is important in order to form a crosslinked cured film with excellent uniform film formation properties or surface smoothness when applied to the surface of a synthetic resin molded product. and is a necessary requirement.

If the boiling point at normal pressure is less than 50°C, after the coating composition is applied, the heat of the organic solvent that evaporates from the coating film cools the substrate surface, causing moisture in the air to condense and cause the coating to deteriorate. The surface smoothness of the film is lost, and if the temperature exceeds 200°C, the organic solvent evaporates from the coating film very slowly, resulting in workability problems. It is preferable because the uniformity and surface smoothness of the cross-linked cured film may be lost due to the lack of balance 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 and cause the film to whiten. do not have. Therefore, the boiling point of the organic solvent used must be between 50°C and 200°C at normal pressure, preferably between 60 and 15°C.
It is in the range of 0°C.

In addition, the viscosity of the organic solvent used must also be 10 cmVoice or less; if it exceeds 10 cmVoise, the viscosity of the coating composition will be high, which will reduce the coating properties and crosslinked cured film performance, which is not preferable.

The amount of the organic solvent to be used 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, and if it is less than 10 parts by weight, it will affect the coating composition. (Poor coating workability due to high viscosity), it becomes difficult to control the film thickness of the applied film, the formation of a uniform film deteriorates, and even the adhesion of the crosslinked cured film to the substrate may deteriorate under severe conditions. descend. On the other hand, if it exceeds 95 parts by weight, it is difficult to control the thickness of the crosslinked cured film, the surface smoothness is lost, and the abrasion resistance is poor, which is not preferable.

Depending on the article on which a crosslinked cured coating is formed, the crosslinked cured coating is required to have extremely high surface smoothness, flexibility, and thinness of the coating. 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 use of organic solvent, and the method for forming coating wave odor should be adjusted. You need to choose accordingly.

The type of organic bath agent to be used must satisfy the conditions mentioned above, specifically alcohols such as ethanol, inpropatol, normal propatool, inbutyl alcohol, normal butyl alcohol, benzene,
Aromatic hydrocarbons such as toluene, xylene, and ethylbenzene, ketones such as acetone and methyl ethyl ketone, ethers such as dioxane, ethyl acetate, and acetic acid n-
These include acid esters such as butyl and propionate ether. These organic solvents may be used alone, or the boiling point and component ratio of the mixture may meet the above requirements (i.
- Two or more types may be used in combination as long as they are within the range.

Also, if it has a specific purpose and satisfies the same conditions as organic solvents and has the same effect, it can be used as a polymerizable monomer-all organic solvent such as methyl acrylate, ethyl acrylate, methyl methacrylate, and styrene. You can also use

Depending on the type of synthetic resin that is the base material, these organic solvents may be used for transparent purposes;
The type of organic solvent used should be determined to form a cross-linked cured film on the surface, as the dye and pigment TG of the colored base material may be removed and discolored, or the base material itself may be prone to cracking. It is desirable to select and use the material as appropriate depending on the type of base material or purpose.

In the present invention, in order to apply the coating composition to the surface of a synthetic resin molded article and form a crosslinked cured film, ultraviolet rays,
It is necessary to irradiate with active energy rays such as electron beams or radiation. Among these, the method using ultraviolet scarlet irradiation is the most preferred crosslinking and curing method from a practical standpoint.

When using ultraviolet rays as an energy beam for crosslinking and curing a fully coated film, it is necessary to add a photosensitizer to the coating composition that can initiate a polymerization reaction upon irradiation with ultraviolet rays. Specific examples of such photosensitizers include benzoin, benzine methyl ether, benzine ethyl ether, penzoin inglobil ether, acetoin,
butyroin, toluoin, benzyl, benzophenone,
Carbonyl compounds such as p-chlorobenzophenone and p-methoxybenzophenone, sulfur compounds such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide, azobisisobutyronitrile, azobis-
Examples include azo compounds such as 2,4-dimethylvaleronitrile, and 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, preferably o, oi to 10 parts by weight, based on the total of 100 parts by weight of the monomer mixture (4) and the organic solvent (J3). This is within the scope of the department. 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 compositions used in the present invention, if necessary.

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

In the present invention, synthetic resin molded products used in the production of wear-resistant synthetic resin molded products include various synthetic resin molded products, regardless of thermoplastic resin or thermosetting resin, such as polymethyl methacrylate resin, polycarbonate resin, polycarbonate resin, etc. Allyl diglycol carbonate resin, polystyrene II
Sheet-shaped molded products, film-shaped molded products, rond-shaped molded products, and various injection molded products manufactured from resin, acrylonitrile-styrene copolymer resin (As resin), polyvinyl chloride resin, acetate resin, ABS resin, polyester resin, etc. Examples include: Among these molded products, molded products manufactured from polymethyl methacrylate resin, polycarbonate resin, polyallyl diglycol carbonate resin, etc. have excellent optical properties, heat resistance,
It is often used to take advantage of its properties such as impact resistance.
Since there is also a strong demand for improved wear resistance, these molded products are particularly preferred as synthetic resin molded products used in the present invention.

The various molded products used in the present invention described above can be used as they are, but if necessary, pre-treatments such as cleaning, etching, corona discharge, active energy ray irradiation, dyeing, and printing may be used. can.

Further, as a method for applying the above-mentioned coating composition to a synthetic resin molded article, 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 part of the target synthetic resin molded product, brush coating or flow coating9 is suitable, and if the surface shape of the molded product is complex, spray coating or molded product If the shape of the molded product is relatively flat and symmetrical, then spin coating is suitable, and if the shape of the molded product is rond or sheet-like, dip coating is suitable.

The amount of coating composition to be applied to the surface of the synthetic resin molded article varies depending on the amount (in the monomer mixture contained in the coating composition) and the purpose; It is necessary to apply the coating so that the film thickness is in the range of 1 to 30 microns. The coating amount of the coating composition corresponding to this may be adjusted to give a coating film of approximately 1.5 to 300 microns.

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 may occur. This is not preferable because it may cause a decrease in 5g1a of the molded product itself.

As mentioned above, there are various methods for applying the coating composition, but among them, the dipping method is limited to some extent by the shape of the synthetic resin molded product, but it is difficult to apply the coating process. It has the advantages of being easy to use, with little loss of paint composition, excellent workability and productivity, and excellent reproducibility. On the other hand, in order for dip coating to be possible and to take advantage of its advantages, the paint used therein must satisfy the following conditions.

In other words, the viscosity of the paint is low and it is easy to form a coat by dipping, the thickness of the coat can be controlled and reproducibility is excellent, and the viscosity of the paint does not change over time and it has excellent storage stability. You are required to be present.

The coating composition used in the present invention satisfies these requirements when the viscosity at 20° C. is 15 centivoise 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.

In addition, depending on the use of synthetic resin molded products with a cross-linked hardened film formed on the surface, after forming hardening waves, bending is performed under appropriate heating, cutting, and cutting such as drilling are performed. It is required to withstand severe conditions such as large deformation and strain during installation of parts or during 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 more preferable it is, but on the other hand, if it becomes extremely thin, the abrasion resistance decreases, so in such a case, the thickness of the crosslinked cured film should be in the range of 1 to 9 μm, taking into consideration the balance. It is preferable.

At the technical level of using conventional polyfunctional (metacoacrylate monolayers or mixtures thereof) as cross-linked cured film forming materials, it has excellent abrasion resistance, surface smoothness, film thickness uniformity, transparency, film appearance, etc. It is impossible to form an excellent thin cross-linked cured film as described above on the surface of a synthetic resin molded product.

However, in the coating composition used in the present invention, 20
A coating composition prepared so that the viscosity at °C is 15 centivoise or less is applied to the surface of a synthetic resin molded product by dip coating, and crosslinked and cured to improve wear resistance, surface smoothness, and film. It has become possible to form a transparent crosslinked cured film with a thickness of 1 to 9 μm, which is excellent in 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. It is better to volatilize at least 50% by weight of the organic bath agent (B) contained in the paint coating applied to the surface of the synthetic resin molded article, and then fully irradiate it with active energy rays. If active energy rays are irradiated onto a coated film containing 50 or more of an aqueous bath agent, the surface smoothness of the crosslinked cured film may be impaired depending on the type of organic bath agent, bubbles may be generated in the film, or crosslinking may occur. This is undesirable because phenomena such as organic solvent remaining in the cured film and whitening of the film occur.

In order to crosslink and cure the applied film, external radiation 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 usually at a temperature of 20 to 2000 K is used.
The electron door taken out from the V electron beam accelerator must be irradiated with active energy mk such as radiation such as α rays, β rays, and γ rays. From the point of view of practicality or workability,
The most preferred radiation source is ultraviolet light.

The atmosphere for irradiating the active energy brick is nitrogen gas,
Of course, it can be used in an inert gas atmosphere such as carbon dioxide gas or in an atmosphere with a reduced oxygen concentration, but the coating composition used in the present invention has excellent abrasion resistance and other properties even under a normal air atmosphere. It is possible to form a cured film. 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 is extremely excellent in 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 peel off or peel off even under harsh conditions or environments.
It does not cause cracks and is extremely useful for applications such as organic window glasses, lighting equipment covers, reflectors, mirrors, eyeglass lenses, sunglass lenses, and optical lenses.

The content of the present invention will be explained in more detail below with reference to Examples. Note that the measurement and evaluation in the examples were performed in the following manner.

(1) Abrasion resistance a) Surface hardness - Pencil hardness according to JISK 5651-1966 Scratch test...... Manipulation test with 000 steel wool ○... Even if lightly rubbed There is almost no spot on the surface △... If you rub it lightly, a little crane will appear on the surface ×
... Even if rubbed lightly, the surface is severely scratched (same level as the base resin) (2) Cross-cut-cellotape peel test on adhesive crosslinked cured film. In other words, make 100 film cutting lines that reach the base material once on the film, 11 times in both the vertical and horizontal directions, with 20 stitches per interval, then paste cellophane tape on top of it and peel it off rapidly. . Repeat this cellotape operation three times at the same location.

○...6 times <No peeling marks on the cross-linked cured film even after turning the film △...Number of peeling marks after turning the film 3 times 1 to 5 degrees
Pieces×・・・Number of peeling stitches after turning 3 times 51~
100 pieces (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 6 cm, and a strip-shaped test piece with a width of 6 cm and a length of 5 crn is formed. Cut out the strip, apply force from both ends of the strip to apply bending deformation strain, and determine the angle from the horizontal plane of the test piece when a crank occurs in the coating. This is a large bending angle 11 of 1li4, and the larger this angle is, the better the flexibility of the coating is.

(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 86°C for 1 hour. . After repeating this several times, various tests are performed.

(5) Measurement of surface smoothness ○...The surface smoothness of the coating was very good and could be said to be a mirror surface.

Δ: The smoothness of the surface of the coating is good, but it tends to be slightly disturbed and cannot be said to be a mirror surface.

×...The surface tends to be disturbed and the smoothness is poor.

Example 1 A curing liquid as shown in Table 1 was prepared, and 2■ methacrylic resin plates (Mitsubishi Rayonso, trade name: Acrylite) were added to it.
- The plate was immersed and pulled up at a speed of 05 cm/sec to form a coating. After leaving it as it is for 10 minutes, the board coated with the paint composition was irradiated with ultraviolet rays from a high-pressure mercury lamp (2 KW HO-L21 manufactured by Iwasaki Electric) for 15 seconds from a distance of 20 meters on each side of the board in the atmosphere described in Table 1. did.

The results obtained are shown in Table IK.

As shown in Experiment Nos. 1 and 3 in Table 1, the coating composition of the present invention exhibits crosslinking and curing properties comparable to those in an inert atmosphere of nitrogen gas.

Further, it can be seen that when a hexafunctional (meth)acrylate other than the one of the present invention is used as in Experiment No. 4, it does not crosslink and cure in air.

Example 2 A 2fi methacrylic resin board was immersed in a coating composition as shown in Table H, and the board was pulled up at a speed of 0-5 cm/see to form a coating. After leaving it for 10 minutes, it was exposed to a high-pressure mercury lamp (Iwasaki Kameki 2K) in an air atmosphere.
W HO-L21 type) UV rays are applied to both sides of the plate at 20 cr.
Irradiation was performed for 15 seconds from a distance of Pl.

The results obtained are also shown in Table H.

As is clear from Table ■, the compositions that do not meet the conditions of the paint composition used for this button light (experiment numbers 2, 5 and 4)
The smoothness of the painted cured film surface was poor, and a mirror surface could not be obtained.

Example 6 Dipentaerythritol Pentaacrylate-6 F01 Graves
, 2.2-bis(4-acryloxyphenyl)propane 10]i lid, tetrahuman furfuryl acrylate 2
0 parts by weight, 20 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 uniformly applied to a 2-thick methacrylic resin cast molded plate using a bar coater. After leaving it for 5 minutes, remove the coated surface from both sides 20cm apart.
Ultraviolet light from a KW high-pressure mercury lamp was irradiated in the air for 10 seconds. As is clear from the obtained result table ■, the thickness of the cross-linked cured film is! It can be seen that when the thickness is +5μ, the flexibility is inferior.

Example 4 Pentaerythritol tetraacrylate 101 elutriate,
Pentaerythritol triacrylate 18 parts by weight, 2
, 2-bis(4-acryloxyjethoxyphenyl)propane 5 ff1itIB, 7 parts by weight of 2-hydroxyglobyl acrylate, 60 parts by weight of t-butyl alcohol and 2 parts by weight of benzoin ethyl ether. Immerse various synthetic resin molded plates shown in ■,
．． The plate was pulled up at a speed of 6 (7)/sec to form a coating. After leaving to stand for 5 minutes, both sides were irradiated for 10 seconds from a distance of 20 m using a 2 KW high pressure mercury lamp in 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 Table IV.

Example 5 15 parts by weight of dipentaerythritol hexaacrylate, 45 parts by weight of dipentaerythritol pentaacrylate, 10 parts by weight of dipentaerythritol tetraacrylate, 5 parts by weight of λ2-bis(4-7-IJroxydiethoxyphenyl)clopane, A liquid obtained by stirring and mixing 25 parts by weight of tetrahydrofurfury + J rate and 4 parts by weight of benzoisopropyl ether is used as liquid A, and a mixture of 80 parts by weight of isopropyl alcohol and 20 parts by weight of toluene is used as liquid t-B. A? A uniform coating composition was obtained by mixing [1] and Solution B in the proportions shown in Table 1.

A cast molded plate made of methacrylic resin having a thickness of 5ttas was immersed in these compositions, and then pulled up at a speed of 0.5 m/sec to form a coating film of the composition on the surface of the molded plate. After 10 minutes, add 2
A cross-linked cured film was formed on the surface of the molded plate by irradiating both sides with ultraviolet rays from a KW high-pressure mercury lamp from a distance of 2 UJcm for 13 seconds. Table V shows the evaluation results of various performances of the obtained molded products.

As is clear from these results, the dip coating method makes it relatively easy to adjust 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 centivoise 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,
Diventaerythritol benta, 20 parts by weight of acrylate, 5 parts by weight of pentaerythritol triacrylate,
To a mixture of 42 parts by weight of monomer and sensitizer (8 parts by weight of 2-hydroxyethyl acrylate and 2 parts by weight of benzoin ether ether), 58 parts by weight of the organic solvent shown in Table 1 was added and mixed. A uniform coating composition was prepared. A methacrylic resin cast plate having a thickness of 2 layers was immersed in these compositions 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 Table 3.

As is clear from the results in Table 2, the use of organic solvents other than those used in the present invention is not preferred because the coating film formation properties and the appearance of the cured film are poor.

Example 7 A coating composition as shown in Table ■ was prepared and applied to a thickness of 3M.
The mixture was sprayed onto the outer surface of a conical methacrylic resin injection molded product with a radius of 60 mm and a height of 50 mm to form a coating having an average thickness of about 20 μm.

Leave this in an air atmosphere for 60 minutes, and
Ultraviolet light from a 2 KW high-pressure mercury lamp is irradiated for 20 seconds from a distance of
A cross-linked cured film of μ was formed.

The abrasion resistance of the outer surface of the obtained molded product, the 'M' rowability and the smoothness of the coating were all good, with a score of 6.0. Phenyl)propane 4 [1 part, 5 parts by weight of tetrahydrofurfuryl acrylate, 2 parts by weight of 2-hydroxy 7'ropylacrylate, 65 parts by weight of Improvyl alcohol, 0.8 parts by weight of benzophenone and 12 parts by weight of benzoin isobutyl ether are stirred. A polycarbonate extruded plate with a thickness of 3 cm is immersed in the FIL covering material composition (obtained by mixing).
．． The plate was pulled up at a pulling rate of 6 cm/Sec to form a coating. After 10 minutes, this was crosslinked and cured by irradiating it with ultraviolet rays from a 2KW high-pressure mercury lamp for 9 seconds from a distance of 15 crn on both sides.

The appearance of the obtained film was very good, the film thickness was 5.5μ, the abrasion resistance was 5H in terms of 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,
12 parts by weight of dipentaerythritol pentaacrylate, 6 parts by weight of pentaerythritol triacrylate, 7 parts by weight of ethoxyethyl acrylate, 50 parts by weight of ethyl alcohol, 20 parts by weight of xylene and 7 parts by weight of benzophenol.
A lens made of polyallyl diglycol carbonate was immersed for 5 minutes in a coating composition prepared by stirring and mixing 1 part by weight and 1 part by weight of benzoin ethyl ether to form a 0.45 cm.
/ sec. After 10 minutes, this lens was irradiated for 10 seconds with a 6 KW high pressure mercury lamp from a distance of 20 cIn on both sides. The thickness of the cross-linked cured film of the obtained lens was 54μt0, and its abrasion resistance was 8H.
There were no scratches in the steel wool abrasion test.

Regarding the adhesion of the film, there was no peeling in the cross-cant cellotape test, and the film had a mirror-like smoothness, making it completely usable as an optical product.

Claims (1)

[Scope of Claims] t The following general formula (where n is 0 or an integer of 1 to 4, at least three of X are CH, =CR-Coo- groups, and the remainder is -OH group). R represents hydrogen or a methyl group Polyfunctional monomer of taerythritol poly(meth)acrylate (a) 30-9
5 parts by weight and the following general formula % formula % (where RI is hydrogen or a methyl group, n is 0 or 1
Y 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 Y's may be the same or different when n is 2 or more. ) Bifunctional monomer (b) 0 to 60 parts by weight and 2 or less (meta) monomers in one molecule
It has an acryloyloxy group and has a boiling point of 150℃ at normal pressure.
5 to 70 parts by weight of monomer (c) having a viscosity of 20 centivoise or less at 20°C) (total 100 parts by weight) 5 to 90 parts by weight, at least 1 to form a homogeneous solution when mixed with (into the body mixture)
95 to 10 parts by weight of organic solvent (seed) and 0 parts of photosensitizer (C)
~10 parts by weight (based on a total of 100 parts by weight of the monomer mixture (4) and organic solvent (g))) is applied to the surface of the synthetic resin molded product, and then air Production of synthetic resin molded articles with excellent wear resistance and surface smoothness, characterized by forming a crosslinked cured coating with a film thickness of 1 to 50 μm on the surface of the synthetic resin molded article by irradiating active energy rays in Method. 2. A watch claim characterized in that after applying a paint composition to the surface of a synthetic resin, 50% or more of the organic solvent contained in the applied paint is volatilized and then irradiated with active energy pulses. A method for producing a synthetic resin molded article having excellent wear resistance and surface smoothness according to item 1. 1 %Flf Claim 1 characterized in that the synthetic resin molded product is methacrylic resin or polycarbonate resin
A method for producing a synthetic resin molded product with excellent wear resistance and surface smoothness as described in 2.