JP2623268B2 - paint remover - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention relates to a method of dispersing a silicone macromonomer in an uncombined state in a main part comprising a graft copolymer containing a silicone macromonomer, The present invention relates to a release agent capable of forming a treated film having an excellent adhesion balance with an adhesive surface.

2. Description of the Related Art Conventionally, a silicone-based release agent made of a silicon resin has been known as a release agent for imparting release properties to the back surface of a substrate made of a plastic film or a laminated paper in an adhesive tape or the like.

However, in the case of the conventional silicone-based release agent, there is a problem that the balance between the adhesion of the resulting treated film to the substrate and the release property to the adhesive surface is poor. If the adhesion of the treated film to the substrate and the adhesive surface is unbalanced, for example, in the case of an adhesive tape, if it is left in a roll for a long period of time or exposed to high temperatures, it will be difficult to rewind, Causes the problem of transfer to the adhesive surface and a decrease in adhesive strength. Further, in the case of a protective sheet, if an adherend such as a metal plate is covered and stacked, a treatment film is transferred to cause a problem of contaminating the adherend.

Means for Solving the Problems The present inventors have overcome the above problems and developed a release agent capable of forming a treatment film having an excellent balance between adhesion to a substrate and release from an adhesive surface. As a result of diligent research, the present inventors have found that the object can be achieved by dispersing the silicone macromonomer in an uncombined state in the main part composed of a copolymer having the silicone macromonomer as a graft component, and the present invention. Was reached.

That is, the present invention comprises a silicone macromonomer having a molecular weight of 1,000 to 50,000 having a monoethylenic double bond at a terminal, and a monomer having a glass transition point of 20 ° C. or more, and a copolymerizable monomer with the macromonomer. The main part consisting of a copolymer having a weight average molecular weight of 10,000 to 1,000,000 having a graft structure in which the content of the silicone macromonomer unit is 2 to 50% by weight and the silicone portion forms a side chain is contained in the silicone. An object of the present invention is to provide a release agent characterized in that the macromonomer is dispersed in an uncombined state in an amount of 5 to 70% by weight based on the total amount of the silicone macromonomer unit in the main part.

Action The copolymer having the graft structure described above exhibits good releasability from the adhesive surface based on the silicone moiety in the side chain, and exhibits good adhesion to the base material based on the main chain.
Further, by changing the ratio of the silicone macromonomer unit introduced into the copolymer, the adhesion balance between the substrate and the adhesive surface is controlled. On the other hand, the releasability is also controlled by controlling the amount of the silicone macromonomer dispersed in the main part in an uncombined state.
The silicone macromonomer unit in the copolymer is difficult to separate based on the compound state, and the uncompounded silicone macromonomer separates from the main part based on having the same structure as the silicone part in the copolymer. Hard to transfer to contact objects such as adherends and adhesive surfaces.

Illustrative Components of the Invention The copolymer used in the present invention comprises a silicone macromonomer and a monomer copolymerizable with the macromonomer, and has a graft structure in which the silicone moiety forms a side chain. The preparation is, for example, a silicone macromonomer having a monoethylenic double bond at a terminal,
It can be performed by reacting with a copolymerizable monomer for forming a main chain by a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method, or the like. preferable.

The silicone macromonomer used in the preparation of the copolymer is composed of a polydiorganosiloxane having a monoethylenic double bond at the terminal of the molecular chain. From the viewpoint of the release performance of the obtained release agent in the treated film, those having a weight average molecular weight of 1,000 to 50,000 are suitable, and those having a weight average molecular weight of 2,000 to 20,000 are preferred. Representative examples of the silicone macromonomer that can be used include those represented by the following general formula.

_{CH 2 = CR-COO-C} 3 H 6 -Si (OSi (CH 3) 3) 3 CH ₂ CRCR—COO—C ₃ H ₆ —SiX ₃ (where R in the above formula is hydrogen or a methyl group;
It is _{-OSi (CH 3) 2 -OSi (} CH 3) _3. In the above chemical formula, the methyl group bonded to the silicon atom may be an ethyl group or a phenyl group, and is not limited to the above in the present invention.

On the other hand, as the copolymerizable monomer, those which can form a main chain having a glass transition point of 20 ° C. or higher, especially 30 to 200 ° C. under the copolymerization by copolymerization with the silicone macromonomer described above are used. Can be When the copolymer has a glass transition point of the main chain of less than 20 ° C., the resulting treated film has poor film strength and poor adhesion to a substrate, which is not preferable. The copolymerizable monomer is appropriately selected and used depending on the material of the substrate to be treated so that the obtained copolymer has good adhesion to the substrate. Representative examples of copolymerizable monomers that can be used include acrylic acid or methacrylic acid esters, styrene or its derivatives, acrylic acid, methacrylic acid, vinyl acetate, and acrylonitrile. Only one copolymerizable monomer may be used, or two or more copolymerizable monomers may be used. It is appropriately determined so that the glass transition point of the main chain is 20 ° C. or higher.

As the copolymer used in the present invention, those having a silicone macromonomer unit content of 2 to 50% by weight are suitable, and those having a content of 5 to 35% by weight are preferred. If the content is less than 2% by weight, the obtained release agent will have poor releasability on the adhesive surface, and if it exceeds 50% by weight, the obtained release agent will have poor adhesion to the substrate. The weight average molecular weight of the copolymer is suitably from 10,000 to 1,000,000, preferably from 30,000 to 300,000. If the weight average molecular weight is less than 10,000, adhesion to the substrate will be poor, and if it exceeds 1,000,000, application to the substrate will be difficult, which is not preferable.

The release agent of the present invention is obtained by dispersing a silicone macromonomer in an uncombined state in a main portion composed of a copolymer. As the dispersion method, a method in which unreacted silicone macromonomer remains during preparation of the copolymer is preferable from the viewpoint of uniform dispersibility. The content (dispersion amount) of the unpolymerized silicone macromonomer is preferably 5 to 70% by weight, more preferably 60% by weight or less, particularly preferably 55% by weight or less, based on the total amount of the silicone macromonomer unit in the main part. If the content exceeds 70% by weight, contacting substances such as an adhesive surface and a metal plate are liable to be stained by blooming. In addition, when the unreacted silicone macromonomer remains more than necessary by applying the above dispersion method, the content can be adjusted by washing the reaction product using an appropriate solvent. .

The release treatment using the release agent of the present invention can be performed by a known method. Therefore, the coating amount is 0.1 to 10 g / m ² (solid content) by an appropriate means such as a gravure coater.
The coating can be performed by coating the surface of the base material to be processed so as to obtain the following, and then drying it to form a film. There is no particular limitation on the application target. Above all, back treatment of adhesive tape based on paper, plastic laminated paper, cloth, plastic laminated cloth, plastic film, metal foil, etc., production of release tape temporarily attached to the adhesive surface, metal plate etc. It is preferably used for the production of a protective sheet for protecting the surface.

Effect of the Invention The treated film comprising the release agent of the present invention has an excellent balance between the adhesion to the surface to be treated and the releasability to the adhesive surface. Further, it is less likely to fall off from the surface to be treated, and is excellent in non-staining property for contact objects such as an adhesive surface. Furthermore, it has excellent stability over time and heat resistance. As a result, when applied to an adhesive table, it should be easy to rewind even when stored in a roll form for a long period of time, even at high temperatures, and be superior in maintaining the adhesive strength of the adhesive surface. Can be.
Further, when applied to a protective sheet, the adherend can be made less likely to be contaminated.

Example 1 30 parts (parts by weight, hereinafter the same) of a silicone macromonomer represented by the formula, 40 parts of butyl methacrylate, and 30 parts of methyl methacrylate were dissolved in toluene in the presence of 1 part of 2,2'-azobisisobutyronitrile. Inside, polymerization treatment was performed so that unreacted silicone macromonomer remained. The weight average molecular weight of the obtained copolymer is 200,000, and the glass transition point of the main chain is 51 ° C.
The remaining amount of unreacted silicone macromonomer is about 45
% By weight.

Subsequently, the reaction product was washed with heptane, and the content of the uncombined silicone macromonomer was adjusted to 28% by weight to obtain the release agent of the present invention.

Example 2 Was polymerized in toluene in the presence of 0.5 part of benzoyl peroxide in toluene to leave unreacted silicone macromonomer remaining. The weight average molecular weight of the obtained copolymer was 150,000, the glass transition point of the main chain was 72 ° C., and the remaining amount of the unreacted silicone macromonomer was about 55% by weight.

Subsequently, the reaction product was washed with heptane, and the content of the uncombined silicone macromonomer was adjusted to 14% by weight to obtain the release agent of the present invention.

Example 3 15 parts of a silicone macromonomer represented by the formula, 80 parts of methyl methacrylate, and 5 parts of acrylic acid were added to benzoyl peroxide.
Polymerization treatment was performed in ethyl acetate in the presence of 0.3 part so that unreacted silicone macromonomer remained. The weight average molecular weight of the obtained copolymer was 450,000, the glass transition point of the main chain was 104 ° C., and the remaining amount of the unreacted silicone macromonomer was about 40% by weight.

Then, the reaction product was washed with heptane, and the content of the uncombined silicone macromonomer was adjusted to 9% by weight to obtain the release agent of the present invention.

Comparative Example 60 parts of ethyl acrylate and 40 parts of acrylonitrile were polymerized in toluene in the presence of 0.5 part of benzoyl peroxide to obtain an acrylic polymer having a weight-average molecular weight of 150,000, and a polydimethyl having a weight-average molecular weight of 5,000. 100 parts of siloxane was added and mixed to obtain a release agent.

Evaluation test The thickness of the surface-treated release agent obtained in Examples and Comparative Examples was 25μ.
m of polyethylene terephthalate film was coated so as to have a solid coating amount of 0.3 g / m ² and dried at 80 ° C. for 2 minutes to obtain a release film, which was subjected to the following tests.

[Peeling force] The adhesive surface of a piece of acrylic adhesive tape with a width of 20 mm is pressure-bonded to the treated surface of the release film by a method in which a 2 kg rubber roller is reciprocated once, and left under an atmosphere of 50 ° C for 24 hours.
Peel off the adhesive tape piece from the sample left for 6 hours in an atmosphere at 65 ° C and 65% RH (180 ° peel, peeling speed 300mm /
Min) and the force required for peeling were measured.

[Residual adhesive strength] In an atmosphere of 20 ° C and 65% RH, the pressure-sensitive adhesive tape piece after the above-mentioned peeling force measurement was pressed on a washed surface of a stainless steel plate (SUS304) by a method of reciprocating a 2 kg rubber roller once and left for 30 minutes. The force required for peeling was measured in the same manner as described above. Then, from the measured values, the ratio of the pressure-sensitive adhesive tape piece before the peeling force measurement to the value measured by the same method was calculated, and this was defined as the residual adhesive force (rate).

[Non-contaminating property] A release film is placed on the cleaning surface of a stainless steel plate (SUS304) through the treated surface, and a pressure of ² kg / cm ² is applied to the film at 30 ° C. and 90% RH for 30 days. After standing, the release film was peeled off and the stainless steel plate was observed for contamination. Then, the case where no contamination by the treated film was observed was evaluated as ○, and the case where it was observed was evaluated as x.

 The results are shown in the table.

The treated film comprising the release agent of the present invention is excellent in the balance between the adhesive force to the substrate and the adhesive surface, and excellent in stability over time and heat resistance, based on the peel force and the residual adhesive force in the table. In addition, it can be seen from the table that the non-staining property is excellent.

Claims (2)

(57) [Claims] 1. A silicone macromonomer having a molecular weight of 1,000 to 50,000 having a monoethylenic double bond at a terminal and a monomer copolymerizable with the macromonomer forming a main chain having a glass transition point of 20 ° C. or higher. A silicone macromonomer unit having a content of 2 to 50% by weight and a silicone part having a graft structure in which a side chain forms a graft structure having a weight average molecular weight of 10,000 to 1,000,000, and a main part comprising a copolymer comprising the silicone macromonomer. A release agent characterized in that the monomer is dispersed in an uncombined state in an amount of 5 to 70% by weight based on the total amount of the silicone macromonomer unit in the main part. 2. The release agent according to claim 1, wherein the content of the unpolymerized silicone macromonomer is 60% by weight or less.