JPS6050835B2 - Crosslinked curable coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a crosslinked curable coating material composition capable of forming a crosslinked film having improved surface properties and smoothness and excellent wear resistance and adhesion.

Plastic products manufactured from polymethyl methacrylate, polystyrene, polycarbonate, polyacrylic glycol dicarbonate, hard vinyl chloride, cellulose acetate, cellulose, acetate, butyrate, etc.
Aluminum products, brass products, etc. have various advantages such as superior impact resistance compared to glass products, can be manufactured quickly into plastic products, and are inexpensive, so they are suitable for optical products. For example, in addition to organic plate glass, chandeliers, lighting fixture covers, optical lenses, and display devices using light sources, their use is being developed as signboards, ornaments, and other interior decoration products. L
,,mu・）Small pieces, sore sludge △Due to the lack of surface hardness, products that have a hard surface are susceptible to contact with other objects, collisions, and attraction. As a result, the surface is damaged, its aesthetic appearance is impaired, and its optical properties are degraded.

For this reason, plastic products are used in optical products, especially fashion glasses, eyeglass lenses such as sunglasses, cameras,
When used as optical lenses such as magnifying glasses, industrial material lenses used in aircraft window glass, watch lenses, player dust covers, etc., scratches that occur on the surface of plastic products reduce the product value. significantly decreases Various methods have been studied to improve these drawbacks of plastic products.

For example, methods have been proposed in which silicone-based or melamine-based coatings are applied and hardened on the surface of plastic products, but products manufactured using these methods have improved surface abrasion resistance. However, it is not completely satisfactory. Particularly, products manufactured using silicone-based coating materials have the drawback that the adhesion between the coating and the base material is poor, so that cracks are likely to occur at the interface and the coating is likely to peel off. Furthermore, due to the large difference in refractive index at the interface between the coating and the surface of the plastic product, the transmittance of light rays decreases and optical distortion is likely to occur, making it difficult to use these plastic products as optical lenses. A problem arises. The inventors of the present invention have conducted intensive studies to create a coating material that can be used to make molded products that require the above-mentioned abrasion resistance, including plastics, and have improved surface properties such as surface smoothness. As a coating material that can achieve this purpose, a composition containing a fluorine-containing vinyl monomer as a main component of a polyfunctional monomer having three or more (meth)acryloyloxy groups in the molecule on the surface of plastic is used. They discovered that it could be used and completed the present invention.

The constituent components of the coating material of the present invention contain three or more (
Various compounds can be used as the compound having a meth)acryloyloxy group, but in particular, a compound in which the group bonding between each (meth)acryloyloxy group in one molecule has 20 carbon atoms or less, preferably 1 or less carbon atoms. These are compounds that are hydrocarbon residues or hydrocarbon residues having one ether bond.Crosslinked coatings formed from polyfunctional monomers in which these hydrocarbon residues have more than 20 carbon atoms have poor wear resistance. ,
This is not preferable because the adhesion to the base material decreases. These polyfunctional monomers are a combination of acrylic acid or methacrylic acid, its halide or lower alkyl ester, and a trivalent or higher polyhydric alcohol, or a trivalent or higher polyhydric alcohol having one ether bond in the molecule. It can be produced by ordinary addition reactions, dehalogenation reactions, dealcoholization reactions, etc. Trihydric or higher polyhydric alcohols used as starting materials include, for example, glycerin, trimethylolethane, trimethylol. Propane, pentaglycerol, pentaerythritol, etc. 1
Examples of the trivalent or higher polyhydric alcohol having ether bonds include dipentaerythritol, diglycerol, and the like.

A particularly preferred polyfunctional monomer is trime. These include tyrolpropane tri(meth)acrylate, pentaerythol tetra(meth)acrylate, and pentaglycerol tri(meth)acrylate. The coating material of the present invention must contain at least 2 weight percent or more, preferably 3 weight percent or more of these polyfunctional monomers in the total coating material. The content of
It is difficult to form a crosslinked coating with excellent wear resistance from a coating material with a nominal weight of % or less.

However, in the case of articles where the coating base material is relatively thin,
When the film is required to have flexibility, it is preferable to include monomers having two or less (meth)acryloyloxy groups in the molecule. The amount of these other vinyl monomers added is the proportion necessary as a constituent component when it becomes a crosslinked film, and when painting, monomers or alcohol having a diluting effect are added in larger amounts to improve workability. Other solvents such as xylene and the like may also be used in combination. Other vinyl monomers that can be used here include, for example, acrylic acid, methacrylic acid, itaconic acid,
Unsaturated carboxylic acids such as crotonic acid or their alkali salts, these unsaturated carboxylic acids and monohydric alcohols such as methanol, ethanol, propanol, isopropanol, n-butanol, 2-ethylhexanol, hexanol, cyclohexanol, stearyl alcohol , esters obtained by reaction with benzyl alcohol, etc., unsaturated carboxylic acids and diols such as ethylene glycol, propylene glycol, 1,
Monoesters and diesters with 4-butanediol, 1,3-butanediol, neopentyl glycol, diethylene glycol, etc., as well as acrylamide, methacrylamide, styrene, acrylonitrile, methacrylonitrile, glycidyl (meth)acrylate,
Examples include allyl glycidyl ether and vinyl acetate. The fluorine-containing vinyl monomer, which is another component of the coating composition of the present invention, may be any fluorine-containing vinyl monomer as long as it is soluble in the polyfunctional monomer component and can be copolymerized with them. For example, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 2,2,3,3,4,4
, 5,5-octafluoropentyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 1,1,1,3,3,3-hexafluoropropyl (meth)acrylate, 2,2 , 3,4,4,4-hexafluorobutyl (meth)acrylate, 1,1-dihydroberfluoropropyl (meth)acrylate, 1,1-dihydroberfluorobutyl (meth)acrylate, 1,1-
Dihydroberfluoropentyl (meth)acrylate, 1
, 1-dihydroperfluorohexyl (meth)acrylate, perfluoroethoxy 1,1-dihydroberfluoropropyl (meth)acrylate, perfluoropropoxy 1,1-dihydroberfluoropropyl (meth)acrylate, perfluorobutoxy Examples include 1,1-dihydroberfluoropropyl (meth)acrylate, α-fluoroacrylic acid, α-difluoromethylacrylamide, and α-trifluoromethylacrylamide.
These fluorine-containing vinyl monomers are preferably contained in the coating material of the present invention in a proportion of usually 0.01 to 3% by weight, and the coating material containing less than 0.01% by weight is preferred. A cured film applied to a substrate and cured is insufficient in its surface properties, especially in terms of smoothness and aesthetic appearance. It is also possible to produce a coating whose surface smoothness, stain resistance, and other surface properties are lower than those of the cured coating formed from the coating material of the present invention.

The cured film formed from the coating material of the present invention has surface properties such as smoothness, stain resistance, solvent resistance, and crack resistance that are superior to those formed from similar coating materials of the present invention containing surfactants. It is superior to other coatings. Although the technical reasons for these are not clear, compared to those using surfactants as coating surface improvers, fluorine-containing vinyl monomers are more effective than polyfunctional monomers having (meth)acryloyloxy groups, which are the main component of coating materials. Because it is copolymerized into the cured membrane formed from the coating material as the main component, it has excellent solvent resistance without reducing the surface hardness of the coating, and has excellent crack resistance, adhesion, and
It is believed that a cured film with excellent stain resistance, surface smoothness, and aesthetic appearance can be formed. To crosslink the coating material of the present invention, a light beam with a wavelength of 2000 to 8000 A, an α line, a β line, a γ line, and an accelerating voltage of 20 to 20
It is preferable to use active energy rays such as electron beams taken out from a 00K electron beam accelerator as the energy source for curing the coating.

When the light beam is used as an energy source for curing the coating, it is necessary to add to the coating composition of the present invention a sensitizer that can initiate a polymerization initiation reaction upon irradiation with light.

Specific examples of such sensitizers include benzoin, 2-methylbenzoin, benzoin methyl ether,
Carbonyl compounds such as benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, acetoin, butyroin, toluoin, benzyl, benzophenone, etc. Sulfur compounds such as tetramethylthiuram monosulfide, tetramethylthiuram disulfide, etc., such as azobisisobutyroin Azo compounds such as nitrile, azobis-2,4-dimethylvaleronitrile,
Examples include peroxide compounds such as benzoyl peroxide and di-tertiary butyl peroxide. The amount of these sensitizers added to the coating material of the present invention is 0.
The amount is preferably in the range of 0.01 to 1% by weight, and a crosslinked film formed from a coating material to which too much sensitizer is added is undesirable because it causes undesirable coloring and deterioration of weather resistance. In order to apply the coating material of the present invention to an object to be coated, such as a plastic molded product, to form a crosslinked film, the plastic molded product is subjected to pretreatment such as etching and corona discharge treatment as necessary, and then the coating material of the present invention is applied. The material is usually
After coating by a method such as brush coating, dip coating, spin coating, spray coating, or flow coating to a film thickness of 1 to 50 μm, preferably 5 to 20 μm, a xenon lamp, low pressure mercury lamp, medium pressure mercury lamp, Wavelengths 2000-8 emitted from light sources such as high-pressure mercury lamps or ultra-high-pressure mercury lamps
The cross-linked coating may be formed by irradiation with active energy rays such as 000A light, electron beams taken out from an electron beam accelerator, and α-rays, β-rays, and γ-rays.

l When cross-linking and curing the uncured film formed from the coating material of the present invention, it is preferable to remove the polymerization-inhibiting effect of oxygen, and the atmosphere in which the active energy rays are irradiated to the cured film is, for example, nitrogen gas, carbon dioxide gas, diluted It is preferable to irradiate the light beam with an inert gas atmosphere such as a gas or thermal sintering gas, or with a light-transmissive film or plate such as a plastic film such as a polyolefin film or a polyester film, or a light-transmissive film or plate such as a glass plate.

When light irradiation is performed from the back side of the film-forming surface of a plastic product, the cover sheet or film does not necessarily have to be light-transparent, and an aluminum sheet or the like can also be used. Plastics with a cross-linked film obtained by coating and curing the coating material of the present invention have extremely excellent surface hardness, impact resistance, abrasion resistance, scratch resistance due to sticking, and surface smoothness. It has excellent adhesion to materials and has very little optical distortion, making it a molded product with little optical distortion. Furthermore, this product does not cause peeling or cracking of the film even under high temperature and high humidity environments. Therefore, products, especially plastic products, having a film coated with the coating material of the present invention and crosslinked are eyeglass lenses, sunglass lenses, optical lenses,
Useful as a watch lens. The present invention will be explained in more detail with reference to Examples below.

Example 1 Thickness 277!77! A methacrylic resin injection molded lens was prepared using 2 parts of pentaerythritol tetraacrylate, 25 parts of trimethylolpropane triacrylate, 5 parts of 1,4-butanediol diacrylate, 4 parts of methyl methacrylate, 1,1,1,3, The lens was coated by dip coating in a composition consisting of 1 part of 3,3-hequinafluoropropyl methacrylate and 2 parts of benzoin isobutyl ether to form a coating film of the composition on both surfaces of the lens.

After leaving this in a quartz cylinder kept in a nitrogen atmosphere for 3 minutes, infrared light (250W) was applied from a distance of 20Crf1 on both sides of the lens.
was irradiated for 1 minute, and then irradiated with ultraviolet rays emitted from a high-pressure mercury lamp (100 W) for 5 minutes from a distance of 20 cm on both sides of the lens, thereby curing the coating film. I got the lens.
The adhesion, surface hardness, and surface smoothness (strain) of the obtained product were measured. Adhesion was manufactured - sample 6
After repeating 5 cycles of a thermal cycle test in which one cycle consisted of immersion in hot water at 5°C for 1 hour, immediately immersion in ice water, and dry heating at 80°C for 11 hours, the same part was cross-cut. Paste the cellophane tape and then pull it off. A peel test was performed five times. As a result, no peeling of the coating film occurred. The surface hardness was on the order of pencil hardness. Strain is JISB-9905
I measured it according to the method, but it did not occur at all. Comparative Example 1 1, 1, 1, 3, 3, 3 from the composition in Example 1
- A cured coating film was formed in the same manner as in Example 1 using a composition excluding hexafluoropropyl methacrylate.

Adhesion of the cured film to the substrate in the same manner as in Example 1,
When measuring the surface hardness and surface smoothness (presence or absence of distortion),
As for adhesion, there was no peeling in a peel test after 5 thermal cycles, and the surface hardness was on the average, but distortion occurred and the product could not be used as an optical device.

Example 2 Trimethylolpropane acrylate 4, 1,4-butanediol diacrylate w part, methyl methacrylate mark part, 2,2,3,3,4,4, A composition consisting of 1 part of 5,5-octafluoropentyl methacrylate and 2 parts of benzoin isobutyl ether was immersed and applied, and both sides of the board were coated with the composition. A coating film was formed.

This was left to stand for 3 minutes in a quartz cylinder kept at 60°C under a nitrogen atmosphere, and then the coating was cured by irradiating it with ultraviolet rays emitted from a high-pressure mercury lamp (100W) for 6 minutes from a distance of 20cm on both sides of the lens. A plastic plate having a cured film with an average thickness of about 11 μm was obtained. The adhesion, surface hardness, and surface smoothness (strain) were measured in the same manner as in Example 1, and the adhesion showed that peeling occurred in the peel test after 5 thermal cycle tests, and the surface hardness was ■. Indicated.
Also, when strain was measured, no strain was observed. Comparative Example 2 2, 2, 3, 3, 4, 4 from the composition in Example 2
, 5,5,-Octafluoropentyl methacrylate was excluded, and a surface hardness coating film was formed in the same manner as in Example 2. The adhesion and surface hardness were the same as in Example 2. However, distortion occurred and it was impossible to use it as an optical instrument.

Example 3 40 parts of pentaerythritol tetraacrylate, 20 parts of trimethylolpropane triacrylate, 30 parts of 1,6-hexanediol diacrylate, 2,2,3,
4,4,4-hexafluorobutyl acrylate 1 part,
A composition consisting of 2.5 parts of benzoin isobutyl ether was attached to a support stand that could rotate at high speed.
IL1 was applied to a 4T$l thick Acrylite (Mitsubishi Rayon methacrylic resin plate) disk by spray painting method,
The disk was rotated at high speed for 2 seconds in a nitrogen atmosphere to make the coating uniform, and then infrared rays (500W) were irradiated for 1 minute from a distance of 20cm, and then a high pressure mercury lamp (500W) was used in conjunction with the infrared rays. The coating film was cured by irradiating it with ultraviolet rays for 8 minutes to obtain a plastic plate having a cured coating.

Adhesion, surface hardness, and surface smoothness (
As a result of measuring the adhesion, there was no peeling mark in the peel test, and the surface hardness far exceeded the bright pencil hardness.
Moreover, no histness occurred at all. Comparative Example 3 2, 2, 3, 4, 4 in the composition used in Example 3
, 4-Hexafluorobutyl acrylate 1 Tabe was replaced with polyoxyethylene sorbitan monooleate 1 Tabe, which is a nonionic surfactant. A plastic plate with a cured film was formed.

The adhesion, surface hardness, and surface smoothness were measured in the same manner as in Example 1, and the adhesion was determined by Thermacycle Test 5.
Peeling occurred in the peeling test after the test (when the same peeling test was repeated three times with cellophane tape, B pieces of the cross-cuts were peeled off).

), the surface hardness was 7H, and optical distortion occurred, making it impossible to use it as an optical instrument. Example 4 In place of the fluorine-containing vinyl monomer contained in the curable composition used in Example 1, the same amount of fluorine-containing vinyl monomer shown in the table below was used, but crosslinking and curing was carried out in exactly the same manner as in Example 1. When I created a lens whose film was made of methacrylic resin,
The cross-linked cured film had a pencil hardness of 8 to 200 mm, a thermal cycle test of 5 times and a peel test of 5 passes, and its surface smoothness was good and there was no optical distortion.

Claims (1)

[Claims] 1 20% to 99.99% by weight of a polyfunctional monomer having 3 or more (meth)acryloyloxy groups in the molecule, 80% by weight or less of other vinyl monomers, and (meth)
A crosslinked curable coating composition comprising 0.01% to 30% by weight of a fluorine-containing monomer having an acryloyl group.