JPS5996918A - Forming method of surface protection layer - Google Patents

Abstract

PURPOSE:To easily form a surface protection film on a member to be coated by a method wherein a composite sheet comprising a substrate having a photosetting adhesive layer applied thereon is adhered on the coated member, light is radiated to harden the adhesive layer and then only the substrate is separated for removal. CONSTITUTION:A composition consisting of (C) a photo copolymerization initiator (e.g., benzoin) added to a mixture of (A) a photo copolymeric compound having a (meth)acryloyl group [e.g., 1,4-butylene glycol di-(meth)acrylate] and (B) a base polymer emulsion [e.g., water dispersed material resulted from (meth)acrylic acid alkylester through emulsion polymerization] in ratio of about 80:20-10: 90wt%, is coated on a substrate (self-supporting sheet) (e.g., vinyl chloride sheet) to form a composite sheet which comprises a substrate having a photosetting adhesive layer applied thereon. Next, the composite sheet is adhered on a member to be coated (such as a metal or plastic plate) through the adhesive layer, and light is radiated to cause the adhesive layer to be hardened through polymerization. Thereafter, the substrate is separated for removal.

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 the surface of an adherend, and more specifically, it 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. The present invention provides a method for forming a surface protective layer for semi-permanently preventing damage to the surface of an adherend.

Conventionally, the surface protection of adherends such as plate-shaped articles has been carried out by temporarily attaching a surface protection adhesive film before processing, and then applying paint etc. after processing. Q These series of steps start with pasting the film onto a plate-shaped article, then perform processing such as bending, drawing, and punching, and then peeling the film, surface cleaning, gate mounting, etc. Starting with the drying process.

In addition to being complicated and complicated, the cleaning solutions and paints contain large amounts of organic bath agents, which often poses various safety and hygiene problems.

Therefore, the purpose of Ml of the present invention is to provide a method for forming a surface protective layer that can easily perform from surface protection of a plate-shaped article before processing to surface protection after processing. The 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 water-dispersible photocurable adhesive composition containing a photopolymerizable compound having at least one (meth)acryloyl group in the molecule, a photopolymerization initiator, and a base polymer emulsion. A composite sheet that is coated on a self-supporting sheet (or film) to form a photocurable adhesive layer (
or a film) on the surface of the adherend via the adhesive layer, and then irradiated with backlight to cure the adhesive layer, and then only the self-supporting sheet (or film) is peeled off to remove the adhesive layer. This is achieved by forming a surface protective layer made of a cured polymer on the body surface.

According to the present invention, the use of organic bath agents in the manufacturing stage of composite sheets (or films) is eliminated, thereby eliminating safety and hygiene problems, and the covering of plate-shaped articles, etc. before and during processing. Damage to the surface of the adherent is prevented by pasting the adhesive sheet, and after processing, it is protected by a surface protective layer formed by polymerizing and curing a photocurable adhesive layer by irradiating it with light. Therefore, the surface of the adherend is not damaged.

At least one in the molecule used in the practice of the present invention
A photopolymerizable compound having 2 (meth)acryloyl groups is a polyfunctional compound having at least one, preferably two or more, methacryloyl or acryloyl groups as a polymerizable double bond in the molecule. Yes, for example, 1.
4-Butylene glycol di(meth)acrylate% 1
．． 6-hexane gelicoldi(meth)acrylate, neobentylglycol di(meth)acrylate, polyethyleneglycol di(meth)acrynaute, trimethylolpropane tri(meth)acrylate, tetramethylolmethanetetra(meth)acrylate, etc. Examples include monomers and oligomers such as epoxy acrylates, polyester-modified acrylates, and oligoester acrylates, and two or more of these may be used in combination as necessary.

In addition, as a base polymer emulsion, a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 12 carbon atoms alone or a (meth)acrylic acid alkyl ester and (
meth)acrylic acid, 2-hydroxyethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate,
An aqueous dispersion of a polymer or copolymer (including a polymer crosslinked using a crosslinking agent) obtained by polymerizing an unsaturated compound such as styrene, vinyl acetate, or (meth)acrylonitrile using an emulsion polymerization method. (solid content 20-60% by weight) is used.

The blending ratio of the photopolymerizable compound and the solid content of the base polymer emulsion is 80:20 to 10:90, preferably 70:30 to 30:70 (each ratio is a weight ratio), and the compound is 80:20 to 10:90, preferably 70:30 to 30:70 If it exceeds 10%, the cohesiveness of the photocurable adhesive layer before irradiation with light will be poor, causing adhesive to ooze out to the sides, which is undesirable, and if it is less than 10%, sufficient curing will not be obtained, so it is not preferable. -It is undesirable.

The photopolymerization initiator is not particularly limited as long as it promotes the photopolymerization reaction of the compound, but examples include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl needle, α- Benzoins such as methylbenzoin, anthraquinones such as 1-chloroanthraquinone and 2-chloroanthraquinone, pentuphenone, p-chlorobenzophenone,
Examples include benzophenols such as p-dimethylaminobenzophenone, sulfur-containing compounds such as diphenyl disulfide, and tetramethylthiuram disulfide. A water-dispersible photocuring type comprising the above photopolymerizable compound, a photopolymerization initiator, and a base polymer emulsion added in an amount of 0.05 to 20% by weight, preferably 0.5 to 10% by weight. When the compound is in liquid form, the adhesive composition is prepared by adding a mixture of the compound and an initiator directly or, if necessary, using a small amount of an organic solvent.
By mixing the compound and the initiator into the base polymer emulsion, making the mixture of the compound and the initiator into the polymer particles into a water dispersion using water and an emulsifier, and mixing this with the polymer emulsion, the compound is solid. If necessary, it can be obtained by dissolving it using a small amount of a solvent or other liquid compound and then mixing it according to the method described above.

In this way, a water-dispersible photocurable adhesive composition composed of a photopolymerizable compound, a photopolymerization initiator, and a base polymer emulsion is a self-supporting sheet (or film) that is transparent and colored or colorless. ), for example, polyvinyl chloride sheets or films, polyolefin sheets or films (including sheets or films made of ethylene-vinyl acetate copolymer and its cyanide), polyester sheets or films (thickness is preferably 10 to 300 μm) ) is coated or transferred to a thickness of about 1 to 100 μm on one side to form a photocurable adhesive layer, but the composition may contain appropriate amounts of other formulations depending on the purpose. Can be added.

Examples of compounding agents include polymerization inhibitors that prevent thermal polymerization during production and reactions during storage, such as hydroquinone, hydroquinone monomethyl ether, tert-butylcatechol, p-benzoquinone, 2.5-tert-butylhydroquinone, Pigments such as phenothiazine, pigments such as zinc white, yellow lead, and red iron for the purpose of coloring or decoration, dyes such as toluidine red, phthalocyanine blue, and phthalocyanine green, other metal powders, glass peas, glass powder, glass flakes, etc. For example, adhesion-imparting resins such as xylene resin and coumaron resin, which are intended to improve the adhesive strength to the surface of the adherend, may be used.

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 in the form of a plate made of a metal plate, glass plate, wood plate, decorative board, plastic plate, etc. It is attached to the surface of an adherend such as an article via an adhesive layer. Generally, from a self-supporting sheet (or film), a light source such as a high pressure mercury lamp, an ultra-high pressure mercury lamp, a metal halide lamp, a carbon arc lamp, or a xenon lamp is used for 0.3 seconds or more, preferably 3 seconds or more.
The adhesive layer is photopolymerized and cured by irradiation with light for more than a second. 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 caused by the loss of plastic fluidity due to curing, since the adhesive strength of the sheet (or film) is largely due to the plastic flow of the adhesive layer at the time of peeling. This can be done easily from the 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, and before or after the adherend is processed, such as sheet metal cutting or cutting.

As described above, according to the method of the present invention, a surface protective layer that protects the surface semi-permanently is formed by irradiating the composite sheet used for surface protection of the adherend surface and peeling off the self-supporting sheet. It has the characteristic of being able to Of course, the method of the present invention is applicable regardless of the processing of the adherend, etc.
It can be used simply to form a surface protective layer on the surface of an article.

Next, examples of the present invention will be shown. The text middle part means the weight part.

Example 1 2-Ethylhexyl acrylate ~609 Ethyl acrylate 35 Acrylic acid 5 Ion exchange
100 // 50% of the above blended composition
Pour into a 0 ml flask and heat at 70°C under inert gas.
After heating and stirring for 1 hour, 0.05 part of ammonium persulfate was added and reacted at 70° C. for 5 hours to obtain an aqueous dispersion of an acrylic copolymer.

Next, 50 parts of tetraethylene glycol dimethacrylate and 3 parts of benzoyl methyl ether were gradually added dropwise to 100 parts (solid content) of the water dispersion while rapidly stirring the water dispersion, and mixed uniformly. A water-dispersible photocurable adhesive composition was prepared, and this was applied to one side of a polyethylene sheet with a thickness of 60 μm so that the thickness after drying was 10 μm.
A composite sheet was obtained by drying at 00°C for 5 minutes.

Example Butyl acrylate 30 parts Acrylonitrile 40 parts Methyl methacrylate 25 Methacrylic acid
5〃Thioglycolic acid
0.1 Polyethylene glycol decyl ether 3 // Ion exchange water 1
50// Using the above blended composition, an aqueous dispersion of an acrylic copolymer was obtained in the same manner as in Example 1.

On the other hand, a mixture of 60 parts of pentaerythritol triacrylate and 5 parts of benzophenone was added to 60 parts of water containing 1 part of sodium dodenlebenzene sulfonate, and the mixture was rapidly stirred to emulsify, resulting in an aqueous dispersion of the photopolymerizable compound. I got it.

This aqueous dispersion was mixed with 80 parts (solid content) of the acrylic copolymer aqueous dispersion to obtain a water-dispersible photocurable adhesive composition.

This composition was applied to one side of a polyethylene sheet with a thickness of 60 μm so that the thickness after drying was 10 μm, and the mixture was heated at 85°C.
The composite sheet was dried for 5 minutes to obtain a composite sheet.

Example 3 Ethyl acrylate 80 parts Styrene 15 Methacrylic acid
5〃Sodium dodecylbenzenesulfonate 2〃Ion exchange water
120 Using the above blended composition, an aqueous dispersion of an acrylic copolymer was obtained in the same manner as in Example 1.

To 150 parts (solid content) of this aqueous dispersion, 110 parts of trimethylolprobantitrimethacrylate, 30 parts of hydroxyethyl acrylate, and 3 parts of benzoin methyl ether were added.
A water dispersion was added dropwise to the water dispersion with rapid stirring to obtain a water dispersible photocurable adhesive composition. Add this to a thickness of 60
The mixture was coated on a polyvinyl chloride sheet having a thickness of 5 μm after drying, and dried at 100° C. for 5 minutes to obtain a composite sheet.

Table 1 shows the results of characteristic tests conducted using the composite sheets obtained in VC Examples 1 to 3 and forming a surface protective layer.

Table 1 Test method in Table 1 Initial adhesion Crab composite 7-t was cut to a width of 25+o+ and BA
After pasting it on a finished stainless steel plate 5US304 and leaving it for 30 minutes, it was peeled off at 180 degrees and the adhesive strength was measured under 0 conditions (peeling speed 300gIVmin, 20℃ x 65%R)
,H,) After pasting the self-supporting sheet peelable crab composite sheet on a BA-finished stainless steel plate 5US304, it was irradiated with ultraviolet light for about 5 seconds from a distance of 10 cm using a high-pressure mercury lamp (80W/(!F71/1 lamp)), and then self-released. The peeling force of the supporting sheet was measured.Conditions (peeling speed 300 x 7 min,
20°C x 65cm R, H,) Pencil hardness: The hardness of the polymerized cured product (surface protective layer) was measured according to fXSK 5400. Cuts were made at 1 part intervals on the adhesive cured product (surface protective layer). 100 pieces were placed in the shape of a base plate, a commercially available cellophane tape was pasted on it, and then the tape was peeled off to indicate the amount of residue left on the base piece. For example, the fact that a good surface protective layer can be easily formed on an adherend is remarkable.

patent applicant Nitto Electric Industry Co., Ltd. Representative Sanbe Hijikata

Claims (1)

[Claims] A water-dispersible photocurable adhesive composition containing a photopolymerizable compound having at least one (meth)acryloyl group in the molecule, a photopolymerization initiator, and a base polymer emulsion is applied to a self-supporting sheet (or film). ) surface (・(A composite sheet (or film) that is coated to become a photocurable adhesive layer,
The adhesive layer is bonded onto the surface of the adherend through the adhesive layer, the adhesive layer is cured by backlight irradiation, and then only the self-supporting sheet (or film) is peeled off, and the cured polymer is applied to the surface of the adherend. A method for forming a surface protective layer, the method comprising forming a surface protective layer comprising: