JPS6161873B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for forming a surface protective layer on the surface of an adherend, and more specifically, the present invention relates to a method for forming a surface protective layer on an adherend, and more specifically, the present invention relates to a method for forming a surface protective layer on an adherend, and more specifically, it relates to a method for forming a surface protective layer on an adherend, and more particularly, it relates to a method for forming a surface protective layer on an adherend, and more particularly, it relates to a method for forming a surface protection layer on an adherend, and more particularly, it relates to a method for forming a surface protective layer on an adherend, and more particularly, it relates to a method for forming a surface protective layer on an adherend, and more particularly, it relates to a method for forming a surface protective layer on an adherend. The present invention provides a method for forming a surface protective layer to semi-permanently prevent such occurrence. Conventionally, the surface protection of adherends such as plate-shaped articles has been carried out by temporarily attaching a surface protective adhesive film before processing, and then applying paint etc. after processing. It is common for there to be. These series of steps begin with pasting the film onto a plate-shaped article, followed by bending, drawing, and
The process consists of cutting, punching, etc., followed by film peeling, surface cleaning, painting, and drying, which is not only complicated, but also because the cleaning fluid and paint contain large amounts of organic solvents. There were various safety and hygiene issues. Accordingly, a first object of the present invention is to provide a method for forming a surface protective layer that can easily protect the surface of a plate-shaped article before processing and protect the surface after processing. A second object of the present invention is to provide a method for forming a surface protective layer by a simple operation without using an organic solvent during construction. The object of the present invention is to provide a film-forming acrylic photocrosslinkable polymer having at least one (meth)acryloyl group in the molecule and a photosensitizer on the surface of a self-supporting sheet (or film). A composite sheet (or film) formed with a photocurable adhesive layer is laminated onto an adherend surface via the adhesive layer, the adhesive layer is cured by backlight irradiation, and then the self-supporting sheet This is achieved by peeling off only the film (or the film) and forming a surface protective layer made of a cured polymer on the surface of the adherend. According to the method of the present invention, damage to the surface of an adherend such as a plate-shaped article before and during processing is prevented by pasting the composite sheet,
After processing, it is protected by a surface protection layer formed by polymerizing and curing the photocurable adhesive layer by irradiating it with light.
The surface of the adherend will not be damaged. The film-forming acrylic photocrosslinkable polymer having at least one (meth)acryloyl group in the molecule used in carrying out the present invention includes the following acrylic copolymer () containing a functional group. Examples include those with unsaturated monomers () added,
When adding the monomer () to the copolymer (), the polyfunctional compound () may be added to the copolymer () in advance, and then the monomer () may be added. The above-mentioned acrylic copolymer () is a (meth)acrylic acid alkyl ester having an alkyl group of 1 to 12 carbon atoms alone, or a combination thereof with vinyl acetate, vinyl propionate, vinylpyridine, (meth)acrylonitrile, ( 99 to 70 parts by weight of at least one kind of mixture with unsaturated monomers such as meth)acrylamide, diacetone acrylamide, and styrene, and (meth)acrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, and allyl acetic acid. Carboxyl group-containing monomers such as N-methylol acrylamide, hydroxyethyl acrylate,
Hydroxyethyl methacrylate, hydroxypropyl acrylate, acrylic alcohol, monoester of polyethylene glycol and (meth)acrylic acid, pentaerythritol triacrylate, triglycerol diacrylate, monovinyl ether of ethylene glycol or polyethylene glycol, propylene glycol or monopropylene glycol Hydroxyl group-containing monomers such as vinyl ether, primary to secondary amino group-containing monomers such as aminoethyl (meth)acrylate, N-methylaminoethyl (meth)acrylate, N-ethylamiethyl (meth)acrylate, etc. body, 2-(1-aziridinyl)ethyl (meth)
Acrylate, aziridinyl-containing monomers such as 2-(1-aziridinyl)butyl (meth)acrylate, 2-(1-aziridinyl)propyl (meth)acrylate, and epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate. At least one functional group-containing monomer
-30 parts by weight may be copolymerized. As the functional group-containing monomer () added to such an acrylic copolymer (), an acrylic monomer having a functional group that can react with the functional group of the copolymer () is used. Examples thereof include the above-mentioned functional-containing monomers. Therefore, when adding a functional group-containing monomer () to an acrylic copolymer (), if direct addition is not possible, it is possible to add a polyfunctional compound () to the acrylic copolymer () in advance. That is, it is necessary to use the compound () as a linking agent and then add the functional group-containing monomer (). As a polyfunctional compound (), tolylene-
2,4-diisocyanate, tolylene-2,6-
Diisocyanate, diphenylmethane-4,4'-
Containing isocyanate groups such as diisocyanate, naphthylene-1,5-diisocyanate, reaction product of 1 mol of trimethylolpropane and 3 mol of tolylene diisocyanate, reaction product of polyhydric alcohol such as polyethylene glycol or polypropylene glycol and tolylene diisocyanate, etc. Compound, 1,1'-(4-methyl-m-phenylene)-bis-3,3-aziridinyl urea, 1,
1'-(hexamethylene)-bis-3,3-aziridinyl urea, 1,1'-(methylene-di-p-phenylene)-bis-3,3-aziridinyl urea, ethylene bis(2-aziridinylpro pionate)
Azinidinyl group-containing compounds such as, and bisphenol A-type epoxy group-containing compounds represented by the following general formula (a) or (b), (In the formula, n is 0 to 12) and novolak-based epoxy resins. These acrylic copolymers (), acrylic monomers and polyfunctional compounds () have a content of 30 to 99:
It is used in a ratio of 1 to 70:0 to 70 (weight ratio), and is used as a film-forming acrylic photocrosslinkable polymer. If the copolymer ( ) is less than 30, the cured layer will become too hard and brittle, which is undesirable. If it is greater than 99, sufficient curing will not be obtained, which is undesirable. In addition, as a method for adding the monomer () to the copolymer () and introducing a (meth)acryloyl group, a self-supporting sheet (or film) is used.
It is best to let it react before applying it on top.
For example, when using highly reactive substances such as an aziridinyl group and a carboxyl group, they may be reacted by heating after coating. The photosensitizer is not particularly limited as long as it promotes the photopolymerization reaction of the polymer, but examples include benzoin, benzoin methyl ether,
Benzoins such as benzoin ethyl ether, benzoin isopropyl ether, and α-methylbenzoin; anthraquinones such as 1-chloroanthraquinone and 2-chloroanthraquinone; benzophenones such as benzophenone, p-chlorobenzophenone, and p-dimethylaminobenzophenone; Examples include sulfur-containing compounds such as diphenyl disulfide, tetramethylthiuram disulfide, etc., and the photosensitizer is preferably 0.05 to 20% by weight, based on the photocrosslinkable polymer. 0.5~10
It is added in a range of % by weight. In this way, a photocurable adhesive composition composed of a photocrosslinkable polymer and a photosensitizer can be used to form a colored or colorless transparent self-supporting sheet (or film) through which light can pass, such as a polyvinyl chloride sheet. or film, polyolefin sheet or film (including sheet or film made of ethylene-vinyl acetate copolymer and its saponified product), polyester sheet or film (each with a thickness of 10 to 300 μm)
(preferably), with a thickness of approximately 1 to 100 μm on one side.
The composition is applied or transferred to form a photocurable adhesive layer, but appropriate amounts of other compounding agents may be added to the composition depending on the purpose. Examples of compounding agents include polymerization inhibitors that prevent thermal polymerization during production and reactions during storage, such as hydroquinone, hydroquinone monomethyl ether, and tert-
Butylcatechol, p-benzoquinone, 2.5-
tert-butylhydroquinone, phenothiazine, pigments for coloring or decoration such as zinc white, yellow lead, red iron, dyes such as toluidine red, phthalocyanine blue, phthalocyanine green, other metal powders, glass beads,
Glass powder, glass flakes, etc., adhesion-imparting resins such as xylene resin and coumaron resin for the purpose of improving the adhesive force to the adherend surface, or crosslinking agents for the purpose of improving the cohesive force of the adhesive layer ( For example, the polyfunctional compound ()) mentioned above may be mentioned. A composite sheet (or film) composed of a self-supporting sheet (or film) and a photocurable adhesive layer configured in this way can be used as a plate-shaped article made of a metal plate, glass plate, wood board, decorative board, or plastic board. etc., through an adhesive layer. Generally, from the self-supporting sheet (or film) side, high-pressure mercury lamps, ultra-high pressure mercury lamps,
The adhesive layer is photopolymerized and cured by irradiating with light for 0.3 seconds or more, preferably 3 seconds or more using a light source such as a metal halide lamp, carbon arc lamp, or xenon lamp. Then, by peeling off only the support sheet (or film), a surface protective layer made of a cured polymer is formed on the surface of the adherend. Peeling of the support sheet (or film) after curing is due to the plastic flow of the adhesive layer at the time of peeling. This can easily be done from the lost adhesive layer. It will be understood that the light irradiation may be performed after the composite sheet is attached to an adherend such as a plate-shaped article, before or after the adherend is processed. As described above, according to the method of the present invention, the composite sheet used for surface protection of the adherend surface is irradiated with light and the self-supporting sheet is peeled off, thereby providing a surface protective layer that can semi-permanently protect the surface. It has the characteristic of being able to form. Of course, the method of the present invention can be used simply to form a surface protective layer on the surface of an article, regardless of the processing of the adherend. Next, examples of the present invention will be shown. The text middle part means the weight part. Example 1 2-Ethylhexyl acrylate 40 parts Methyl methacrylate 60 Methacrylic acid 5 Benzoyl peroxide 0.2 Ethyl acetate 100 The above blended composition was polymerized at 70°C for 24 hours to obtain an acrylic polymer. Next, 15 parts of tolylene-2,4-diisocyanate and 0.02 parts of dibutyltin dilaurate were added to 100 parts (solid content) of the copolymer, mixed at 70°C for 3 hours, and then cooled to 40°C. Add 20 parts of hydroxyethyl acrylate and mix at 40°C for 5 hours to obtain a film-forming acrylic photocrosslinkable polymer containing acryloyl groups. 1.5 parts of benzophenone is added to 50 parts (solid content) of this copolymer and mixed uniformly.
It was coated on one side of a 60 μm polyethylene sheet so that the thickness after drying would be 5 μm, and dried at 100° C. for 5 minutes to obtain a composite sheet. Example 2 Ethyl acrylate 80 parts Methyl methacrylate 20 Hydroxypropyl methacrylate 10 Azobisisobutyronitrile 0.2 Toluene 100 The above blended composition was polymerized at 70°C for 4 hours to obtain an acrylic copolymer. Next, 6 parts of glycidyl methacrylate and 0.01 part of piperidine are added to 100 parts (solid content) of the copolymer and mixed at 80° C. for 4 hours to obtain a film-forming photocrosslinkable polymer. To 50 parts (solid content) of this polymer, 2 parts of a reaction product of 3 moles of tolylene diisocyanate and 1 mole of trimethylolpropane, 3 parts of benzoin methylol ether, 0.01 part of hydroquinone, and 5 parts of coumaron resin were mixed uniformly. mixed to a thickness of 60μ
The mixture was coated on one side of a polyvinyl chloride sheet of No. m so that the thickness after drying would be 5 μm, and dried at 80° C. for 5 minutes to obtain a composite sheet. Example 3 Vinyl acetate 60 parts Acrylonitrile 20 Ethyl acrylate 20 2-(1-aziridinyl) ethyl methacrylate 14 parts Benzoyl peroxide 0.2 Ethyl acetate 100 The above blended composition was polymerized at 70°C for 4 hours to form acrylic Obtain a copolymer. Next, 7 parts of acrylic acid is added to 100 parts (solid content) of the copolymer and mixed at 60°C for 4 hours to obtain a film-forming acrylic photocrosslinkable polymer. Add 3 parts of benzophenone to 50 parts (solid content) of this polymer, mix uniformly, and add this to the thickness.
It was coated on the surface of a 60 μm polyethylene sheet so that the thickness after drying would be 5 μm, and dried at 80° C. for 5 minutes to obtain a composite sheet. Example 4 Isobutyl acrylate 20 parts Vinyl acetate 20 Methyl methacrylate 60 Acrylic acid 10 Asobisisobutyronitrile 0.1 Toluene 100 The above blended composition is polymerized at 70°C for 4 hours to obtain an acrylic copolymer. Next, for 100 parts (solid content) of the copolymer, 1
-Add 10 parts of aziridinylethyl methacrylate and mix at 60°C for 4 hours to obtain a film-forming photocrosslinkable polymer. To 50 parts (solid content) of this polymer, 1 part benzoin methyl ether and 0.001 part hydroquinone are blended and mixed uniformly, and this is applied to a polyvinyl chloride sheet with a thickness of 60 μm so that the thickness after drying is 5 μm. The composite sheet was coated in the following manner and dried at 100°C for 5 minutes to obtain a composite sheet. Table 1 shows the results of characteristic tests performed using the composite sheets obtained in Examples 1 to 4 and forming a surface protective layer.

[Table] Test method in Table 1 Initial adhesion strength: The composite sheet was cut into 25 mm wide pieces, pasted on a BA-finished stainless steel plate SUS304, left for 30 minutes, and then peeled off at 180 degrees to measure the adhesive strength. Conditions (peeling speed 300mm/min, 20℃ x 65%R.
H) Self-supporting sheet peeling force: Composite sheet
After pasting it on a BA-finished stainless steel plate SUS304, the peeling force of the self-supporting sheet was measured after irradiating it with ultraviolet light for about 5 seconds from a distance of 10 cm using a high-pressure mercury lamp (80 W/cm/lamp). Conditions (peeling speed 300
mm/min, 20°C x 65% RH) Pencil hardness: The hardness of the polymerized cured product (surface protective layer) was measured according to JIS K 5400. Adhesion: Make 100 cuts at 1 mm intervals on the polymerized cured product (surface protection layer) in the shape of a base grid, apply commercially available cellophane adhesive tape to these, then peel off the tape and indicate the percentage of remaining base grids. did. As is clear from the above examples, the method of the present invention is notable for the fact that a good surface protective layer can be effectively formed on an adherend.

Claims (1)

[Claims] 1. A photocurable adhesive layer containing a film-forming acrylic photocrosslinkable polymer having at least one (meth)acryloyl group in the molecule and a photosensitizer on the self-supporting sheet (or film) surface. The formed composite sheet (or film) is laminated onto the surface of an adherend via the adhesive layer, the adhesive layer is cured by backlight irradiation, and then only the self-supporting sheet (or film) is bonded. A method for forming a surface protective layer, which comprises peeling off to form a surface protective layer made of a polymerized cured product on the surface of the adherend.