JPS6050392B2 - Peelable film forming agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a releasable film-forming agent consisting of an emulsion or aqueous composition in an aqueous medium, and more specifically, a releasable film-forming agent that has good adhesion to base materials such as various sheets and papers, and is easily removable. can be controlled and form a coating layer that does not come off.
In particular, the present invention relates to the film-forming agent for release paper that can be preferably used for various labels and pressure-sensitive adhesive tapes.

Release paper is generally attached to the surface of an adhesive layer of various labels, pressure-sensitive adhesive tapes, etc. in order to protect the adhesive layer and prevent it from adhering to other materials.

Such a release paper is required to have appropriate releasability to the adhesive layer and resistance to shedding of the releasable coating layer. In other words, if the releasability is insufficient, it will remain on the adhesive layer during peeling and become a factor that inhibits the adhesion of the adhesive layer, and conversely, if it is excessive, the retention and adhesion of the release paper to the adhesive layer will deteriorate. becomes unable to perform its original function. In addition, if the peeling resistance is insufficient, the peelable coating layer may separate from the base material and transfer to the adhesive layer side during peeling. Conventionally, compositions used to form a peelable coating layer include:
There is a copolymer solution of octadecyl acrylate (or methacrylate) and acrylic acid (or methacrylic acid), but this has insufficient releasability.

On the other hand, silicone solutions have very good releasability, but the releasability becomes excessive and the retention and adhesion of the release paper to the adhesive layer are likely to be impaired. Due to its properties, it does not have sufficient adhesion to paper base materials, and the formed silicone film easily falls off. Furthermore, both of the above compositions are often used in the form of organic solvent solutions, which poses problems from the viewpoint of risks such as fire and explosion4, as well as toxicity and air pollution. In light of the above circumstances, the inventors first filed a patent application in 1973.
No. 5-65565 proposes an aqueous-based releasable film-forming agent that eliminates the use of organic solvents.

This film-forming agent is added to 100 parts by weight of the solid content of the silicone emulsion for the purpose of improving adhesion and peelability to non-wetting, non-porous sheets such as plasticized polyvinyl chloride sheets and polyolefin sheets. It is a mixture containing 20 to 10 parts by weight of the solid content of a resin emulsion, but it is not suitable for use as a release paper for adhesive layers made of strongly adhesive or strongly adhesive substances such as pressure-sensitive adhesive tapes. It has been found that there is still room for improvement in terms of this.This invention was discovered in the course of further research, and it has been found that it has good adhesion to the base material and that peelability can be controlled arbitrarily. Moreover, the present invention relates to a releasable film-forming agent that can form a releasable film layer that does not come off.

That is, the present invention provides the following method: (a) General formula [wherein R1 is a hydrogen atom, an alkoxy group, or a substituted or unsubstituted hydrocarbon group, n means an integer, (2
At least three of the n+2) R1's are hydrogen atoms.

] and (b) an organohydrodiene polysiloxane represented by the general formula [where R2 is a substituted or unsubstituted hydrocarbon group, m
means an integer.

]; and (c) a resin component having a film-forming ability of 5 parts by weight or more and less than 2 parts by weight based on 10 parts by weight of the total amount of components a and b. , and a peelable film-forming agent comprising an aqueous medium composition having a nonvolatile content of 1 to 6% by weight.

In this invention, the organohydrodiene polysiloxane as the component a represented by the above general formula (1) must have at least three silicon-bonded hydrogen atoms in one molecule, and the integer n representing the degree of polymerization must be Although the value is not particularly limited, it is 25. It is desirable that the viscosity at ℃ is 5 centipoise or more.

Specific examples include methylhydropolysiloxane,
Examples include ethyl hydropolysiloxane and vinyl hydropolysiloxane, which are usually used in the form of an aqueous medium such as an emulsion or an aqueous solution. The organopolysiloxane of component b has silicon-bonded hydroxyl groups at both ends of the molecule, as shown by the general formula (■) above, and as with component a, the value of the integer m representing the degree of polymerization is particularly limited. However, the viscosity at 25 C is 3
One with a value of 0 centipoise or higher is recommended.

Component b may be an organopolysiloxane emulsified or water-solubilized in an aqueous medium, but preferably an aqueous emulsion obtained by emulsion polymerization of silane or siloxane is used. The above a component and b component are mixed in the form of an aqueous medium, and the aqueous medium of both components is 10 parts by weight of component b per 100 parts by weight of component a based on the solid content.
It is preferable to use it in a proportion of 0 to 20 parts by weight, preferably 300 to 1000 parts by weight.

Furthermore, acids, alkalis, amines, organic metal salts, etc. are usually used as curing catalysts for both of these polysiloxanes. The amount of this curing catalyst used can be increased or decreased as appropriate depending on the desired curing speed, but is generally in the range of 0.1 to 1 part by weight per 100 parts by weight of the solid content including components a and b. used. The resin component having a film-forming ability as component c may be one that has a strong film-forming ability, can be uniformly mixed with both polysiloxanes in an emulsion or aqueous solution state, and is compatible with the substrate to which it is applied. Particularly preferred are those with high chemical affinity.

Examples of the aqueous medium for the resin component include acrylic polymer emulsions and water-soluble cellulose derivatives for unbleached kraft paper, and ethylene-vinyl acetate copolymer emulsions for polyethylene sheets. , SBR latex, polyvinyl alcohol aqueous solution, etc. can also be used.

Among these, from the viewpoint of the properties of the release film layer obtained by baking the film-forming agent of the present invention on a sheet-like base material, functional groups that can react with the silicon-bonded hydrogen atoms present in the polysiloxane of component a. It is preferable to use an aqueous resin containing (hydroxyl group, carboxyl group) because it can more effectively prevent the outermost polysiloxane cured product constituting the coating layer from falling off the base material. be.

A typical example preferable as an aqueous medium for the resin having the above functional group is the following acrylic copolymer emulsion, in which acrylic acid alkyl ester monomer (alkyl group has 1 to 8 carbon atoms) and/or methacrylate 3 to 1 parts of a carboxyl group-containing copolymerizable monomer per 10 parts of a base monomer prepared by adding an acid alkyl ester monomer (alkyl group having 1 to 8 carbon atoms) or a vinyl monomer copolymerizable with these. Examples include those obtained by copolymerizing a hydroxyl group-containing copolymerizable monomer at a ratio of 1 to (up to) parts by weight.

As the main component acrylic acid alkyl ester monomer, butyl acrylate and 2-ethylhexyl acrylate are most suitable, but other acrylic acid alkyl esters having an alkyl group of 1 to 8 carbon atoms may also be used. , it is also possible to use them together. As the methacrylic acid alkyl ester, methyl methacrylate, ethyl methacrylate, butyl methacrylate, etc. are most suitable, but other methacrylic acid alkyl esters with an alkyl group having 8 or less carbon atoms may also be used. , it is also possible to use them together. Further, copolymerizable vinyl monomers include styrene, vinyl acetate, acrylonitrile, methacrylonitrile, and the like.

Monomers containing carboxyl groups include acrylic acid,
Contains methacrylic acid, maleic anhydride, itaconic acid, etc. Monomers containing hydroxyl groups include 2-hydroxyethyl acrylate, 2-hydroxyphethyl methacrylate, 2-hydroxypropyl acrylate,
These include diethylene glycol monoacrylate, triethylene glycol monoacrylate, tetraethylene glycol monoacrylate, dipropylene glycol monoacrylate, tripropylene glycol monoacrylate, and tetrapropylene glycol monoacrylate. In this invention, the aqueous medium of these resins having film-forming ability contains 5 parts by weight or more and less than 5 parts by weight based on 10 parts by weight of the aqueous medium of both polysiloxanes, based on the solid content. The nonvolatile content in the composition is adjusted to 1 to 6% by volume.

The release film-forming agent obtained in this way is uniformly dispersed when mixed, but when it is applied to various sheet substrates and dried, it has a chemical affinity for the sheet substrate during film formation. The sheet contacting surface is enriched with a certain resin emulsion and/or aqueous solution, and the outermost surface is provided with a substantially two-layer release coating layer containing a polysiloxane reactant.

It can be confirmed by various methods that the outermost surface contains a large amount of polysiloxane reactant. For example, a releasable film forming agent is applied and dried on a sheet base material to form a releasable film layer, and the surface is subjected to ESCA (X-ray photoatomic analysis).
This can be confirmed by measuring the static contact angle of pure water. The major features of the releasable film forming agent of this invention are:
Peeling is achieved by changing the resin component having a film-forming ability of component c in the range of 5 parts by weight or more and less than 2 parts by weight relative to the total amount of polysiloxane of components a and b of 100 parts by weight. It is possible to set the strength to any desired strength.

If the amount is less than 5 parts by weight, the effect of controlling the peeling effect will be poor and the above-mentioned a! Compared to the case of using only an aqueous medium of both polysiloxanes of Yohi B, we cannot find much usefulness.

Moreover, if it exceeds 20 parts by weight, the peeling effect will be poor and the applicability to strongly adhesive materials will be insufficient. The nonvolatile content in the releasable film-forming agent should be 1 to 60% by weight, since if it is too low, the formed film layer will be too thin and the releasability will be insufficient, and if it is too high, the amount of coating will be significantly large. There is a need.

The peelable film-forming agent of the present invention essentially consists of an aqueous medium composition of the above-mentioned components, but dyes, pigments, viscosity modifiers, etc. can be added as necessary.

As explained above, when the releasable film forming agent of the present invention is applied and dried on various sheet base materials, the outermost surface contains a large amount of polysiloxane reactant, and the surface in contact with the base material contains a large amount of polysiloxane reactant. The present invention provides a peelable coating layer consisting essentially of two layers containing a film-forming resin.

The formation of such two types of layers helps to ensure the adhesive strength between the peelable coating layer and the sheet base material, and since the layer between the two layers is a mixture of both layers, the interlayer strength is strong, and the peelable coating layer Provides the effect of preventing falling off from the sheet base material.

Furthermore, by using a resin containing a functional group such as a hydroxyl group that can react with the silicon-bonded hydrogen atom of polysiloxane as a resin with film-forming ability, a crosslinking reaction with the polysiloxane is generated to form a peelable film. It is possible to more effectively prevent the layer from falling off the base material. The release film-forming agent of the present invention is particularly useful for release paper based on unbleached kraft paper from the viewpoint of providing good adhesion to the support film and good release function to the attached adhesive layer. However, other soakable sheet base materials such as Western paper, paperboard, and Japanese paper, and non-soakable base materials such as various synthetic resin sheets or films such as polyethylene, polypropylene, and polyester, and metal foils such as aluminum foil and copper foil. It can also be applied to materials based on

Next, examples and reference examples of the present invention will be shown, but the present invention is not limited to these examples.

In addition, all parts in the following text mean parts by weight. Example 1 The following monomer mixture butyl acrylate was placed in a reaction vessel equipped with a thermometer, a stirrer, a nitrogen inlet tube and a reflux condenser.
50 (parts) Methyl methacrylate
50 acrylonitrile
10 Acrylic acid 32-Hydroxyethyl methacrylate 5 Sorbitan monolaurate 3.2 Alkylbenzenesulfonic acid sodium salt 0.8 Ion exchange water
160 and heated while stirring under a nitrogen stream. When the reaction system reached about 60°C, 02 parts of ammonium persulfate was added as a polymerization initiator to start polymerization, and the polymerization reaction was carried out for about 2 hours. .

After the polymerization reaction was completed, the reaction system was heated to about 65° C. and aged for about 1 hour to obtain an acrylic emulsion containing the copolymer. Next, the following compounds were added to the above emulsion to prepare a releasable film forming agent. Organohydrodiene polysiloxane emulsion (SH-8200 manufactured by Toray Silicone, solid content 40%) 30 (parts)
Organopolysiloxane emulsion with terminal silicon-bonded hydroxyl groups (SH-8701 manufactured by Toray Silicone, solid content 30%)
80 curing catalyst (DC-22K manufactured by Dow Corning, solid content 24%)
10 The above-mentioned acrylic emulsion 5 A peelable membrane-forming agent consisting of an aqueous medium composition with a solid content of 10% as formulated above was applied to one side of an unexposed craft (manufactured by Tomoekawa Paper Manufacturing Co., Ltd., RRP) with a solid content of 1.0 y/d. A sample having a peelable film layer was prepared by uniformly coating the sample in an amount equal to the coating amount and drying by heating at 140'C for 2 minutes.

Adhesive tape (1) Tokyo Denko Knit-
Polyester tape NO. Table 3 shows the measurement results of the peel force, residual adhesive force, and residual adhesive force retention rate at room temperature, as well as the test results for the peelability of the peelable coating layer. Next, regarding the various emulsions used in this example, an acrylic emulsion component alone, a polysiloxane emulsion component containing a curing catalyst alone (B), and the release film forming agent of Example 1 (C)
) were applied to one side of unexposed kraft (described above) at a coating weight of 1.0y/771 solids, and dried by heating at 140'C for 2 minutes. For each sample piece obtained, the treated surface was analyzed by ESCA (X-ray photoatomic analysis) and the static contact angle of pure water was measured, and the results are shown in Table 1. According to Table 1, the coating layer of the releasable film forming agent (C) of Example 1 shows measured values similar to those of the coating layer of the polysiloxane emulsion component alone (B). From this result, it can be seen that the coating layer (C) contains a large amount of polysiloxane reactant on the outermost surface, and a peelable coating layer having a substantially two-layer structure is formed. Example 2 2-ethylhexyl acrylate 30 (parts) Methyl methacrylate 50 acrylonitrile
5 acrylic acid
42-Hydroxyethyl acrylate 3 Sorbitan monolaurate 3.2 Alkylbenzenesulfonic acid sodium salt 0.8 Ion exchange water
160 Using the above monomer mixture,
An acrylic emulsion was produced under the same reaction conditions as in Example 1.

Next, the following compounds were added to the above emulsion to prepare a releasable film forming agent. Organohydrogen polysiloxatone emulsion (SH-8240 manufactured by Toray Silicone Co., Ltd., solid content 40%) 40 (parts)
Organopolysiloxane emulsion with terminal silicon-bonded hydroxyl groups (manufactured by Toray 5 Silicone, SH-490, solid content 38%)
120 curing catalyst (manufactured by Dow Corning, Syl-0ff1171A1 solid content 5
0%) 5 The above acrylic emulsion
10-O Samples were prepared by treating the releasable film forming agent formulated above in the same manner as in Example 1, and the test results are shown in Table 3.

Next, regarding the various emulsions used in this example, an acrylic emulsion component alone (D), a polysiloxane emulsion component containing a curing catalyst alone (E)
, and the releasable film forming agent (F) of Example 2, were applied to one side of a plasticized polyvinyl chloride film at a solid content of 1.0 y/I, in an amount of: 8, It was dried by heating at 140°C for 2 minutes.

For each sample piece obtained, the treated surface was analyzed by ESCA (X-ray photoatomic analysis) and the static contact angle of pure water was measured, and the results are shown in Table 2. Example 3 Organohydrodiene polysiloxane emulsion (Toray silicone SH-82001 (solid content 40%) 40 (parts)
Organopolysiloxane emulsion with terminal silicon-bonded hydroxyl groups (manufactured by Dow Corning, HV-490, solid content 30%)
90 curing catalyst (manufactured by Gou Corning, DC-22K1 solid content 24%)
6 was added, and the solid content was 0.6 on one side of the polyester film (manufactured by Toray Industries, Inc., Lumirror).
It was applied uniformly to a coating amount of q/d, treated in the same manner as in Example 1 to prepare j sample, and measured.

Example 4 40% of SBR latex (manufactured by Nippon Zeon Co., Ltd., Hiker 1571) was used as an aqueous medium of resin having film-forming ability.
A sample was prepared in the same manner as in Example 1, except that the base product was replaced with the acrylic-based 3-mulsion of Example 1,
I took measurements.

Reference example 3 Ethylene-vinyl acetate copolymer emulsion (manufactured by Sumitomo Chemical Co., Ltd., Sumikaflets 4x10
0HS1 solid content 55%) 50 (parts) Organohydrodiene polysiloxane emulsion (Toray Silicone BX-12-80 solid content 40%) 200 Curing catalyst (Dow Corning DC-22K1 solid content 24%) 20 Above The formulation was uniformly applied onto a corona-treated polyethylene film at a coating weight of 0.6 y/d solids,
A sample was formed by processing in the same manner as in Example 1, and measurements were performed.

The test results in Table 3 were measured and observed using the following method.

A clean adhesive tape was affixed to the sample piece and stored at 40°C for 2ff under a load of 20y/d.
1800 peeling tests at a speed of 0 TWt/min (
20°C) and the stress was measured.

Residual Adhesive Strength After measuring the peeling force, the adhesive tape was applied to a BA stainless steel plate using a roller, and after 30 minutes, a 180 peel test (20°C) was performed at a speed of 30 mm/min to measure the stress.

Residual adhesive strength retention rate: The adhesive strength of clean adhesive tape to BA stainless steel plate (875y/50=) is 100%.
It shows the percentage of residual adhesive strength when

This test is to determine whether the peelable coating layer provided on the sample piece is contaminated by peeling off from the adhesive tape. Peeling resistance: Attach the releasable coating layer side of the sample piece to a BA stainless steel plate, place another BA stainless steel plate on top of it, and apply a load of 100y/CTl.
The degree of contamination of BA stainless steel plates was observed after heating and storage at 40°C for 24 hours.

In the table, O is good, Δ is almost good, × is contaminated,
Indicates the degree of shedding of the coating layer. As is clear from Table 3, the sample pieces using the peelable film forming agents of Examples 1 to 4 according to the present invention exhibited moderately light peeling force,
The peeling force can be controlled arbitrarily within an appropriate range, and the high residual adhesive force and retention rate means that the adhesive force between the base film and the peelable coating layer is strong, and it cannot be peeled off with the adhesive tape. It has been shown that it is difficult to remove and provides a good quality releasable surface.

Claims (1)

[Claims] 1(a) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ [However, R_1 is a hydrogen atom, an alkoxy group, or a substituted or unsubstituted hydrocarbon group, and n means an integer. ,
At least three of the (2n+2) R_1 are hydrogen atoms. ] Organohydrodiene polysiloxane represented by (b) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (However, R_2 is a substituted or unsubstituted hydrocarbon group,
m means an integer. ) and (c) a resin component having a film-forming ability of 5 parts by weight or more and less than 20 parts by weight based on 100 parts by weight of the above components a and b, and is non-volatile. A peelable film forming agent comprising an aqueous medium composition having a content of 1 to 60% by weight. 2. The releasable film forming agent according to claim 1, wherein component a has a viscosity of 5 centipoise or more at 25°C. 3. The releasable film forming agent according to claim 1 or 2, wherein component b has a viscosity of 30 centipoise or more at 25°C. 4 100 to 20 parts of b component to 100 parts by weight of a component
0 parts by weight of the releasable film forming agent according to any one of claims 1 to 3. 5 300 to 10 parts of b component to 100 parts by weight of a component
00 parts by weight of the releasable film forming agent according to any one of claims 1 to 3. 6 In the aqueous medium composition, the curing catalyst of component a and component b is contained in an amount of 0.1 to 100 parts by weight per 100 parts by weight of the total amount of component a and component b.
10 parts by weight of the releasable film forming agent according to any one of claims 1 to 5. 7. The releasable film-forming agent according to any one of claims 1 to 6, wherein component c comprises a resin having a functional group capable of reacting with a silicon-bonded hydrogen atom in the molecule of component a. 8 The resin having a functional group has an alkyl group having 1 to 8 carbon atoms.
Base monomer 1 whose main component is an acrylic acid alkyl ester or/and a methacrylic acid alkyl ester
00 parts by weight of the copolymerizable monomer containing a carboxyl group and 1 to 30 parts by weight of the copolymerizable monomer containing a hydroxyl group. Peelable film forming agent. 9. The removable film forming agent according to claim 8, wherein the base monomer contains as a subcomponent a vinyl monomer copolymerizable with the main component, acrylic acid alkyl ester or methacrylic acid alkyl ester.