JPH08302297A - Acrylic foam supporter for tacky tape - Google Patents

Abstract

PURPOSE: To obtain the subject supporter for a tacky tape having excellent water resistance with a slight lowering of strength and elongation in wet state, comprising a foamed sheet composed of a composition having an outer shell of core/shell-type polymer fine particles as a self-curing fluorine compound copolymer and a body coloring pigment. CONSTITUTION: A composition composed of an aqueous dispersion of an acrylic polymer containing core/shell-type polymer fine particles comprising (A) an inner core of preferably an acrylic polymer having a glass transition temperature of -30 deg.C to 0 deg.C and (B) an outer shell of a self-curing fluorine compound copolymer, and (C) a body coloring pigment is foamed and coated on a sheet, dried and cured to obtain the objective supporter. Preferably, the component B is 1-20 pts.wt. and the component C is 5-40 pts.wt. based on 100 pts.wt. of the component A.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an acrylic foam support for adhesive tapes. More specifically, the present invention provides
The present invention relates to an acrylic foam support for pressure-sensitive adhesive tape, which has excellent water resistance and has little decrease in strength and elongation in a wet state.

[0002]

2. Description of the Related Art Adhesive tapes having a pressure-sensitive adhesive composition layer formed on one or both sides of an acrylic polymer foamed sheet are widely used. Acrylic polymer foam sheet, which is the base material of this adhesive tape, so-called acrylic foam support for adhesive tape, is usually made by mechanically agitating an emulsion of acrylic polymer and foaming it. It is applied on top of the above and dried to manufacture. In this case, it is necessary to mechanically stir the acrylic emulsion to foam, and the foam generated by foaming must be uniform-sized foam. Contains a fairly large amount of surfactant.
In the acrylic foam support produced from such an acrylic emulsion, a surfactant is present, so that the water resistance is deteriorated, and when the adhesive tape is used in a wet state, a decrease in strength and elongation becomes a problem. . Therefore, it is required to develop an acrylic foam support for an adhesive tape, which has excellent water resistance.

[0003]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of providing an acrylic foam support for pressure-sensitive adhesive tape, which is excellent in water resistance and has little decrease in strength and elongation even when used in a wet state. It is a thing.

[0004]

As a result of intensive studies to solve the above problems, the present inventors have found that core / shell type polymer fine particles whose outer shell is a self-crosslinking fluorine compound copolymer. We have found that a foamed sheet obtained from a composition comprising an extender pigment has excellent water resistance, and have completed the present invention based on this finding. That is, the present invention is
(1) A composition comprising an acrylic polymer aqueous dispersion containing core / shell type polymer fine particles in which the inner core is an acrylic polymer and the outer shell is a self-crosslinking fluorine compound copolymer, and an extender pigment After foaming, apply on the sheet,
Acrylic foam support for pressure-sensitive adhesive tape obtained by drying and crosslinking, (2) Acrylic foam support for pressure-sensitive adhesive tape according to item (1), wherein the glass transition temperature of the inner core acrylic polymer is -30 to 0 ° C. And (3) the outer shell is a copolymer of acrylic acid ester or methacrylic acid ester having a perfluoroalkyl group, (1) or (2)
An acrylic foam support for pressure-sensitive adhesive tape according to the above item.

The acrylic foam support for pressure-sensitive adhesive tapes of the present invention contains an acrylic polymer having an inner core of an acrylic polymer and an outer shell of a self-crosslinking fluorine compound copolymer containing core / shell type polymer particles. An aqueous polymer dispersion is used. An acrylic polymer aqueous dispersion containing such core / shell type polymer particles is prepared by emulsion-polymerizing an acrylic monomer using water as a medium, and then further adding a fluorine compound having a polymerizable double bond and self-polymerization. It can be obtained by adding a mixture of a polymerizable monomer having a crosslinkable functional group and, if necessary, another monomer and continuing the polymerization.
In the present invention, the acrylic monomer that is polymerized to form the inner core is not particularly limited, and known acrylic monomers can be used. Examples of such acrylic monomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate and 2-methacrylate.
Hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, acrylic acid, methacrylic acid, glycidyl acrylate, glycidyl methacrylate, tricyclodecyl acrylate, tri Cyclodecyl methacrylate, dimethyl siloxane acrylate, dimethyl siloxane methacrylate, isononyl acrylate, isononyl methacrylate, isodecyl acrylate, isodecyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, acrylonitrile, methacrylonitrile, 2-
Methoxyethyl acrylate, 2-methoxyethyl methacrylate, 2-sulfoethyl acrylate, 2-sulfoethyl methacrylate and the like can be mentioned. In the present invention, when polymerizing the inner core, a monomer other than the acrylic monomer can be copolymerized, if necessary. Examples of such a monomer include aromatic monomers such as styrene and methylstyrene, vinyl ester monomers such as vinyl acetate, chlorine-containing monomers such as vinyl chloride and vinylidene chloride, and N- Vinyl formamide, N-
N-vinylamide monomers such as vinylacetamide,
Mention may be made of maleic acid, fumaric acid, maleic anhydride, etc., and salts thereof, unsaturated dibasic acid monomers such as esters, etc.

In the present invention, the glass transition temperature of the inner core acrylic polymer is preferably -30 to 0 ° C. When the glass transition temperature of the inner core is lower than -30 ° C, the acrylic foam support may be too soft and lack the strength and rigidity required to support the pressure-sensitive adhesive composition layer. When the glass transition temperature of the inner core exceeds 0 ° C, the acrylic foam support may be too hard, and the adhesive tape may not have sufficient flexibility and shape conformability. In the present invention, the polymerization method for obtaining the aqueous acrylic polymer dispersion of the inner core is not particularly limited, and for example, a known emulsion polymerization method or the like can be used. For emulsion polymerization, for example, a monomer emulsion is prepared by mixing a monomer, water and an emulsifier, and if necessary, a polymerization initiator, a polymerization degree adjusting agent, etc., and polymerizing the reaction vessel with water and if necessary. Polymerization can be carried out by charging an initiator and the like, replacing the atmosphere with an inert gas, heating to the polymerization temperature and then dropping a monomer emulsion. Alternatively, a reaction vessel is charged with all components such as a monomer, water, an emulsifier, a polymerization initiator, and a polymerization degree adjusting agent, stirred and emulsified, and the atmosphere is replaced with an inert gas, after which the temperature is raised to the polymerization temperature. By doing so, the polymerization can be performed.

In the present invention, a self-crosslinking fluorine compound copolymer is formed as an outer shell on the outside of the acrylic polymer fine particles to form core / shell type polymer fine particles. As the polymerizable fluorine compound for forming the self-crosslinking fluorine compound copolymer, for example,

Embedded image And the like can be preferably used. However, in the above formula, R ¹ , R ² and R ³ are hydrogen or a methyl group, and R _f
Is a perfluoroalkyl group represented by -C _n F _{2n + 1.} In the present invention, an acrylic acid ester or a methacrylic acid ester having a perfluoroalkyl group in which R _f has 6 to 12 carbon atoms can be preferably used. In the present invention, examples of the polymerizable self-crosslinking compound for forming the self-crosslinking fluorine compound copolymer, which is the outer shell, include N-methylol acrylamide and N-
Methylol methacrylamide and the like can be used. The methylol group of these compounds forms a crosslinked structure by a dehydration reaction when the polymer aqueous dispersion is dried by heating,
The strength and water resistance of the resulting acrylic foam support are improved. In the present invention, the outer shell self-crosslinking fluorine compound copolymer may be copolymerized with other monomers in addition to the polymerizable fluorine compound and the polymerizable self-crosslinking compound. As such a monomer, it can be appropriately selected and used from the monomers used for the acrylic polymer of the inner core described above, but acrylic acid esters, methacrylic acid esters, maleic acid Acids and their esters, fumaric acid and their esters, vinyl esters and the like can be particularly preferably used. The self-crosslinking fluorine compound copolymer that forms the outer shell is 20 to 90% by weight of the polymerizable fluorine compound and 0.5 to 0.5 of the polymerizable self-crosslinking compound.
It is preferable to copolymerize 5% by weight and 5-79.5% by weight of other monomer, and 30-50% by weight of the polymerizable fluorine compound, 1-3% by weight of the polymerizable self-crosslinking compound and other It is further preferable that the monomer of 47 to 69% by weight is copolymerized.

In the present invention, the outer shell of the self-crosslinking fluorine compound copolymer is formed outside the inner core of the acrylic polymer to obtain an acrylic aqueous dispersion containing core / shell type polymer particles. be able to. A polymerizable fluorine compound, a polymerizable self-crosslinking compound and other monomers, water and an emulsifier, and if necessary, a polymerization initiator, a polymerization degree adjusting agent and an organic solvent are mixed to prepare a monomer emulsion. The outer shell of the self-crosslinking fluorine compound copolymer can be formed by dropping this monomer emulsion into an acrylic polymer aqueous dispersion serving as an inner core and conducting polymerization. In the present invention, an extender pigment is added to an acrylic polymer aqueous dispersion containing core / shell type polymer particles. There is no particular limitation on the extender pigment used, and for example, it is possible to use synthetic extender pigments such as calcium carbonate, magnesium carbonate, barium sulfate, silica, alumina and aluminum hydroxide, and natural extender pigments such as clay and talc. it can. Further, if necessary, a general inorganic pigment such as iron oxide, titanium oxide, or zinc oxide can be used in combination with the extender pigment. The proportion of each component in the present invention is 1 to 2 for the outer shell self-crosslinking fluorine compound copolymer per 100 parts by weight of the inner core acrylic polymer.
It is preferably 0 part by weight, and more preferably 5 to 15 parts by weight of the outer shell self-crosslinking fluorine compound copolymer. Further, the blending ratio of the extender pigment is preferably 5 to 40 parts by weight, more preferably 10 to 20 parts by weight, with respect to 100 parts by weight of the inner core acrylic polymer.

In the present invention, as a dispersant for dispersing the polymer in water, as a foaming agent for mechanically foaming the aqueous dispersion, and for maintaining the stability of the foamed foam. Use a surfactant for. The surfactant used is not particularly limited, and known nonionic surfactants, anionic surfactants, cationic surfactants and the like can be used. Among these, polyoxyethylene monoalkyl ether, poly Particularly preferably, nonionic surfactants such as oxyethylene alkyl phenyl ether and sorbitan esters, and anionic surfactants such as sodium dodecylbenzenesulfonate, fatty acid-modified sodium glutamate, and fluorine-based anionic surfactants are used. You can In the present invention, a known resin dispersant, a thickener, a viscosity modifier, a cross-linking agent, etc. may be added to the composition comprising the acrylic polymer aqueous dispersion and the extender pigment, if necessary. . In the present invention, a composition comprising the acrylic / polymer aqueous dispersion containing the core / shell type polymer particles and an extender pigment is foamed. The foaming method is not particularly limited, but foaming by mechanical stirring can be preferably used. Upon mechanical agitation, the composition foams to a total volume of preferably 1.5 to 5.0 times, more preferably a total volume of 2.0 to 3.0 times. The resulting foaming liquid is applied to a sheet, dried and crosslinked to obtain the acrylic foam support for pressure-sensitive adhesive tape of the present invention. Apply the foaming liquid to the release sheet,
The sheet can be peeled off after laminating the acrylic foam support for pressure-sensitive adhesive tape and the pressure-sensitive adhesive layer, or it can be applied to a sheet of ordinary plastic or the like, and the three layers of the pressure-sensitive adhesive layer, acrylic foam support and plastic sheet can be used. Can be manufactured.

In the present invention, an acrylic polymer aqueous dispersion containing a core / shell type polymer fine particle having an inner core of an acrylic polymer and an outer shell of a self-crosslinking fluorine compound copolymer, and an extender pigment. Instead of blending, an aqueous dispersion containing core / shell type fine particles in which the inner core is extender pigment fine particles and the outer shell is a self-crosslinking fluorine compound copolymer, and an aqueous dispersion containing acrylic polymer fine particles After the composition containing the liquid is foamed, it is applied to a sheet, dried and crosslinked to obtain an acrylic foam support for pressure-sensitive adhesive tape. FIG. 1 is a cross-sectional view of an adhesive tape using the acrylic foam support for adhesive tape of the present invention.
FIG. 1A shows an acrylic foam support 1 for adhesive tape.
1 (b) is a double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer 2 and a pressure-sensitive adhesive layer 3 on both sides of an acrylic foam support 1 for pressure-sensitive adhesive tape. . In the double-sided pressure-sensitive adhesive tape, the pressure-sensitive adhesive layers on both sides can have the same composition, or the pressure-sensitive adhesive layers on both sides can have different compositions. In the acrylic foam support for pressure-sensitive adhesive tapes of the present invention, since the outer shell of the core / shell type polymer particles is a self-crosslinking fluorine compound copolymer, the water resistance is remarkably improved and the pressure-sensitive adhesive tape is used under wet conditions. Even so, the strength and elongation of the support are not significantly reduced, and the support can be used stably.

[0011]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Example 1 100 parts by weight of n-butyl acrylate as a monomer, 2
-Ethylhexyl acrylate 670 parts by weight, acrylic acid 5 parts by weight, 2-hydroxyethyl methacrylate 30
Parts by weight and 195 parts by weight of methyl methacrylate, 0.1 part by weight of n-dodecyl mercaptan as a polymerization degree adjusting agent,
As an emulsifier, 10 parts by weight of sodium dodecylbenzenesulfonate, 30 parts by weight of polyoxyethylene lauryl ether, and 300 parts by weight of distilled water were mixed and stirred to obtain a monomer emulsion M-1. A solution prepared by dissolving 4 parts by weight of ammonium persulfate in 500 parts by weight of distilled water was charged into the reaction vessel, the atmosphere inside the reaction vessel was replaced with nitrogen, and then the temperature was raised to 60 ° C. The temperature of the reaction vessel is 60 ℃
The emulsion of the above-mentioned monomer was added dropwise over 5 hours with stirring while maintaining the above temperature to obtain an acrylic polymer aqueous dispersion P-1. The solid content of the acrylic polymer aqueous dispersion P-1 was 55% by weight, and the viscosity at 20 ° C. was 400 cps. The glass transition temperature of this acrylic polymer is −
It was 28 ° C. CH ₂ = CHCOOCH ₂ as a monomer
40 parts by weight of CH ₂ R _f (wherein R _f is a perfluoroalkyl group having an average carbon number of about 8), 2 parts by weight of N-methylolacrylamide, 20 parts by weight of lauryl methacrylate and 38 parts by weight of 2-ethylhexyl acrylate,
Emulsion M containing a fluorinated monomer by mixing and stirring 5 parts by weight of polyoxyethylene lauryl ether as an emulsifier, 1 part by weight of azobisisobutylamidine hydrochloride as a polymerization initiator, 175 parts by weight of distilled water, and 60 parts by weight of acetone. -2 was obtained. The reaction vessel was charged with 1,000 parts by weight of the acrylic polymer aqueous dispersion P-1 at a temperature of 60.
After adjusting the temperature to ℃ and stirring, add 250 parts by weight of the above emulsion containing the fluorine-based monomer, and polymerize while stirring at 60 ℃ for 10 hours, the inner core is an acrylic polymer, the outer shell Acrylic polymer aqueous dispersion P-2 containing core / shell type polymer particles, which is a self-crosslinking fluorine compound copolymer, was obtained. Acrylic polymer water dispersion P
-2, 100 parts by weight, 5 parts by weight of calcium carbonate as an extender pigment, 0.5 parts by weight of aqueous ammonia for viscosity adjustment, 1 part by weight of sorbitan monooleate as a foaming stabilizer and a crosslinking agent. Of Sumitex Resin M-3
3 parts by weight of [Sumitomo Chemical Co., Ltd., trade name] was blended and mechanically agitated using an Oaks mixer until the total volume became 2.5 times, and foaming was performed. This foaming liquid is applied on a release paper to a thickness of about 0.5 mm and dried at a temperature of about 130 mm.
The polymer was crosslinked by heating at ˜140 ° C. for 5 minutes to obtain a foamed sheet having a thickness of about 0.3 mm. This foam sheet is 15mm
The test piece was cut into a width, and the strength and the elongation of the test piece were measured with a Shopper strength and elongation tester.
It was 0 g and the elongation was 600 to 620%. Further, the test piece was immersed in warm water of 40 ° C. for 48 hours, and then the adhering water was wiped off to measure the strength and elongation immediately, and the strength was 90 to 100 g and the elongation was 400 to 450%. SK Dyne 1310 which is the main agent of acrylic adhesive
[Souken Chemical Co., Ltd., trade name] 100 parts by weight, and SK Dyne L-45 which is a curing agent [Souken Chemical Co., Ltd., trade name] 1.5
100 parts by weight of the resulting solution is mixed with release paper.
² After coating and drying, laminate the above foam sheet, and
Aging was performed at -30 ° C for 7 days to obtain an adhesive tape. The same method was repeated for the other surface to obtain an adhesive tape having the form shown in FIG. 1 (b) having an acrylic foam as a support and having adhesive layers on the front and back of this support. Example 2 As monomers, 100 parts by weight of n-butyl acrylate, 100 parts by weight of lauryl methacrylate, 570 parts by weight of 2-ethylhexyl acrylate, 5 parts by weight of acrylic acid, 2
-Hydroxyethyl methacrylate 30 parts by weight and methyl methacrylate 195 parts by weight, n as a polymerization degree adjusting agent
0.1 part by weight of dodecyl mercaptan, 10 parts by weight of sodium dodecylbenzenesulfonate as an emulsifier, 30 parts by weight of polyoxyethylene lauryl ether and 30 parts of distilled water
By mixing and stirring 0 part by weight, a monomer emulsion M-3 was obtained. Except that a monomer emulsion M-3 was used instead of the monomer emulsion M-1,
Polymerization was performed in exactly the same manner as in Example 1 to obtain an acrylic polymer aqueous dispersion P-3. Acrylic polymer aqueous dispersion P-
3 and an emulsion M-2 containing a fluorinated monomer were used, and the core was an acrylic polymer and the outer shell was a self-crosslinking fluorinated compound copolymer in exactly the same manner as in Example 1. Acrylic polymer aqueous dispersion P-4 containing / shell type polymer particles was obtained. 100 parts by weight of acrylic polymer aqueous dispersion P-4, 5 parts by weight of aluminum hydroxide as an extender pigment, 0.5 parts of ammonia water for adjusting viscosity.
Parts by weight, 1 part by weight of sorbitan monooleate as a foaming stabilizer, and Sumitex resin M-3 as a crosslinking agent.
3 parts by weight of [Sumitomo Chemical Co., Ltd., trade name] was blended and mechanically agitated using an Oaks mixer until the total volume became 2.5 times, and foaming was performed. This foaming liquid is applied on a release paper to a thickness of about 0.5 mm and dried at a temperature of about 130 mm.
The polymer was crosslinked by heating at ˜140 ° C. for 5 minutes to obtain a foamed sheet having a thickness of about 0.3 mm. With respect to this foamed sheet, the strength and the elongation before and after the hot water immersion were measured in the same manner as in Example 1. The strength before the hot water immersion was 110 g and the elongation was 6
0 to 610%, strength after immersion in warm water 90 to 95
The elongation was 400 to 450%. Comparative Example 1 100 parts by weight of acrylic polymer aqueous dispersion P-1, 5 parts by weight of calcium carbonate as an extender pigment, 0.5 parts by weight of aqueous ammonia for viscosity adjustment, and sorbitan mono as a foaming stabilizer. 1 part by weight of oleate and 3 parts by weight of Sumitex Resin M-3 [Sumitomo Chemical Co., Ltd., trade name] as a cross-linking agent were used, and the total volume was increased to 2.5 times by using an Oaks mixer. The mixture was mechanically stirred until foaming. This foaming liquid is applied on a release paper to a thickness of about 0.5 mm, and while being dried, it is heated at a temperature of about 130 to 140 ° C. for 5 minutes to crosslink the polymer to form a foamed sheet having a thickness of about 0.3 mm. Got With respect to this foamed sheet, the strength and elongation before and after hot water immersion were measured in the same manner as in Example 1. The strength before hot water immersion was 120 to 130 g, the elongation was 500 to 550%, and the strength after hot water immersion was 40 to 40%. The elongation was 50 g and the elongation was 200 to 250%. Comparative Example 2 100 parts by weight of acrylic polymer aqueous dispersion P-3, 5 parts by weight of calcium carbonate as an extender pigment, 0.5 parts by weight of aqueous ammonia for viscosity adjustment, and sorbitan mono as a foaming stabilizer. 1 part by weight of oleate and 3 parts by weight of Sumitex Resin M-3 [Sumitomo Chemical Co., Ltd., trade name] as a cross-linking agent were used, and the total volume was increased to 2.5 times by using an Oaks mixer. The mixture was mechanically stirred until foaming. This foaming liquid is applied on a release paper to a thickness of about 0.5 mm, and while being dried, it is heated at a temperature of about 130 to 140 ° C. for 5 minutes to crosslink the polymer to form a foamed sheet having a thickness of about 0.3 mm. Got With respect to this foamed sheet, the strength and elongation before and after hot water immersion were measured in the same manner as in Example 1. The strength before hot water immersion was 120 to 130 g, the elongation was 520 to 550%, and the strength after hot water immersion was 40 to 40%. The elongation was 50 g and the elongation was 200 to 250%. Table 1 shows the values of strength and elongation of the foamed sheets of Examples 1 and 2 and Comparative Examples 1 and 2 before and after immersion in warm water.

[0012]

[Table 1]

From the results shown in Table 1, it can be seen that the acrylic foam support for pressure-sensitive adhesive tapes of the present invention shows a small decrease in elongation and strength even after immersion in warm water.

[0014]

The acrylic foam support for pressure-sensitive adhesive tapes of the present invention has water repellency and excellent water resistance, so that the strength and elongation are not significantly reduced even in a wet state, and the pressure-sensitive adhesive tapes are stable in a wet state. Can be used.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an adhesive tape using an acrylic foam support.

[Explanation of symbols]

 1 Acrylic foam support for adhesive tape 2 Adhesive layer 3 Adhesive layer

Front Page Continuation (72) Inventor Yoshinori Konno 1-7-6 Nihonbashi Bakurocho, Chuo-ku, Tokyo Dainichi Seika Kogyo Co., Ltd.

Claims (3)

[Claims] 1. An acrylic polymer aqueous dispersion containing core / shell type polymer particles, the inner core of which is an acrylic polymer and the outer shell of which is a self-crosslinking fluorine compound copolymer, and an extender pigment. An acrylic foam support for pressure-sensitive adhesive tape obtained by foaming the composition, applying it to a sheet, drying and crosslinking. 2. The acrylic foam support for pressure-sensitive adhesive tapes according to claim 1, wherein the glass transition temperature of the acrylic polymer of the inner core is -30 to 0 ° C. 3. The acrylic foam support for pressure-sensitive adhesive tapes according to claim 1, wherein the outer shell is a copolymer of acrylic acid ester or methacrylic acid ester having a perfluoroalkyl group.