JPH01304170A - Adhesive tape and preparation thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an adhesive comprising a pressure-sensitive adhesive layer provided on an acrylic crosslinked foam sheet whose adhesive properties are improved by blending an epoxy resin component and an acrylic resin component. This invention relates to a tape and its manufacturing method.

Conventional techniques and problems Conventionally, emulsions of acrylic polymers whose main monomer is acrylic acid alkyl esters have been foamed by mechanical stirring in the presence of a foaming agent or by mixing foam beads. There has been known an adhesive tape in which a pressure-sensitive adhesive layer is provided on the cross-linked foamed sheet obtained by processing the foam, forming it into a sheet, and then cross-linking the resulting cross-linked foam sheet. This adhesive tape is often used as a fixing material for hanging stems such as hooks, name plates, or hard adherends such as metal plates.

However, since the adhesive force between the crosslinked foam sheet and the pressure-sensitive adhesive layer is poor, there have been problems in which the adherend falls off or the ends of the adherend peel off and the fixed state cannot be maintained for a long period of time.

Means for Solving the Problems The present invention overcomes the above problems by using an epoxy resin and an acrylic resin.

That is, the present invention provides a pressure-sensitive adhesive layer on one or both sides of a cross-linked foam sheet, and the cross-linked foam sheet contains an acrylic polymer component whose main monomer is an acrylic acid alkyl ester and an epoxy resin component. and an acrylic resin component, the epoxy resin component and the acrylic resin component are contained in a total amount of 1 to 200 parts by weight per 100 parts by weight of the acrylic polymer, and the acrylic resin component is an epoxy resin component. and an emulsion containing 100 parts by weight of an acrylic polymer whose main monomer is an acrylic acid alkyl ester, an epoxy resin and an acrylic resin. A mixed emulsion containing 1 to 200 parts by weight in total and an emulsion in which the acrylic resin content is 0.1 to 4 times the weight of the epoxy resin is foamed and then expanded. and a pressure-sensitive adhesive layer is attached to one or both sides of a crosslinked foam sheet formed by crosslinking the spreading layer in the presence of a crosslinking agent or an epoxy resin curing agent. A manufacturing method is provided.

Effect: By adding an epoxy resin component and an acrylic resin component, the adhesive force between the pressure-sensitive adhesive layer and a crosslinked foam sheet made of an acrylic polymer whose main monomer is an acrylic acid alkyl ester can be improved. I can do it. This improvement in adhesive strength is thought to be due to the distribution of the epoxy resin component and acrylic resin component on the surface of the crosslinked foam sheet. Further, by setting the contents of the epoxy resin component and the acrylic resin component within the above range, the properties of the crosslinked foam sheet made of the acrylic polymer other than the adhesive properties can be preserved without deteriorating.

Examples of Constituent Elements of the Invention The adhesive tape of the present invention is made of a cross-linked foam sheet with a pressure-sensitive adhesive layer attached on one or both sides, and the cross-linked foam sheet is made of an acrylic polymer, an epoxy resin, and an acrylic resin. is the component. The content of the epoxy resin component and the acrylic resin component is 1 to 200 parts by weight, preferably 3 parts by weight, per 100 parts by weight of the acrylic polymer.
~50 parts by weight. If the total content is less than 1 part by weight, the effect of improving the adhesive force with the pressure-sensitive adhesive layer is poor;
If the amount exceeds 0 parts by weight, the properties other than the adhesive properties of the crosslinked foam sheet made of the acrylic polymer will be impaired.

The content of the acrylic resin component is 0.1 to 4 times the weight of the epoxy resin component. If the content of the acrylic resin component is less than 0.1 times the weight of the epoxy resin component, the epoxy resin component is likely to separate, and if it exceeds 4 times the weight of the epoxy resin component, the effect of improving the adhesion is poor.

The adhesive tape of the present invention can be manufactured, for example, as follows.

That is, one side of a crosslinked foam sheet formed by foaming a mixed emulsion of an acrylic polymer, an epoxy resin, and an acrylic resin, then developing it, and crosslinking it in the presence of a crosslinking agent or an epoxy resin curing agent. This can be done by applying pressure-sensitive adhesive layers to both sides.

The mixed emulsion may be prepared by emulsifying a mixture of resin components consisting of an acrylic polymer, an epoxy resin, and an acrylic resin, or by separately forming an emulsion of each resin component and mixing them. You may. The latter preparation method is preferred from the viewpoint of surface distribution of the epoxy resin and the like.

As the acrylic polymer, those known for conventional acrylic cross-linked foam sheets whose main monomer is an alkyl ester of acrylic acid or methacrylic acid are used. The emulsion can be obtained as an emulsion made of an emulsion polymerization solution, or can be obtained by stirring and emulsifying an acrylic polymer in surfactant-containing water. The content of the acrylic polymer in the emulsion is preferably 30 to 70% by weight, particularly 50 to 65% by weight, from the viewpoint of mixing operability. The emulsion may optionally contain additives such as thickeners such as carboxylated ethyl acrylate, methyl cellulose, and sodium alginate, pH adjusters such as ammonia and sodium hydroxide, and gelling agents such as polyethylene glycol and polymethyl vinyl ether. It is blended. The total amount of acrylic polymer is 100%.
A suitable amount per part by weight is 30 parts by weight or less. Incidentally, such additives may be added after forming the above-mentioned mixed emulsion.

Epoxy resins include known ones such as bisphenol epoxy resins made by reacting bisphenol A and epichlorohydrin in the presence of an alkali, aliphatic epoxy resins made by reacting aliphatic glycol and epichlorohydrin, and other novolak epoxy resins. can be used.

An emulsion of an epoxy resin can be obtained, for example, by emulsification using surfactant-containing water. The content of epoxy resin in the emulsion is 30 to 70% by weight,
Among these, 40 to 55% by weight is suitable.

The acrylic resin contains an acrylic acid alkyl ester with an alkyl group having 30 or less carbon atoms, especially 14 or less, such as acrylic acid or methacrylic acid methyl ester, ethyl ester, 2-ethylhexyl ester, etc. A polymer, or a product obtained by copolymerizing the above polymer with a modified monomer such as a vinyl monomer such as styrene, vinyl acetate, or vinyl propionate, or a polymerizable monomer having a functional group, is used. Acrylic resins containing polymerizable monomers having functional groups, such as carboxyl groups, hydroxyl groups, amino groups, glycidyl groups, etc., that react with the functional groups of the epoxy resins described above,
It can be preferably used because it can form a strong adhesive state by crosslinking through the functional groups remaining in the foam sheet and the pressure-sensitive adhesive layer. An emulsion of an acrylic resin can also be obtained by an emulsion polymerization method or an emulsification treatment using water containing a surfactant. The content of acrylic resin in the emulsion is 30
~70% by weight, especially 40-55% by weight is suitable.

Incidentally, the surfactant used in the emulsification treatment may be either nonionic or anionic. Typical examples include polyethylene glycol nonylphenyl ether, polyethylene glycol octylphenyl ether, polyethylene glycol alkyl allyl ether, polyethylene glycol oleate, sorbitan sequisate, sodium dodecylbenzene sulfonate, and sodium salt of polyoxyethylene alkylphenyl ether sulfate. can be given.

From the viewpoint of work efficiency, it is preferable that the epoxy resin and the acrylic resin are mixed in advance to form an emulsion, and this is mixed with the emulsion of the acrylic polymer to form a mixed emulsion. The mixing ratio is 100% acrylic polymer
The total amount of epoxy resin and acrylic resin is 1 to 200 parts by weight per part by weight. Preferably, the emulsion prepared by mixing the epoxy resin and the acrylic resin is also prepared by mixing separately prepared emulsions. that time,
Additives such as surfactants, fillers, and thickeners may be added as necessary. The mixing ratio of the acrylic resin to the epoxy resin is 0.1 to 4 times the weight of the epoxy resin. The viscosity of the mixed emulsion containing each resin or polymer component is usually lO
-300 voids (20°C) is suitable from the viewpoint of foaming treatment properties.

The foaming treatment of the mixed emulsion can be carried out, for example, by mechanically stirring the mixed emulsion in the presence of a foaming agent, or by mixing foam beads into the mixed emulsion. Further, both of the above-mentioned methods may be used in combination, and the foaming treatment method is not limited in the present invention. The degree of foaming treatment is such that the volume of the mixed emulsion is 1.5-1 due to the inclusion of microbubbles.
A value of 0 times is appropriate. In the case of a mechanical stirring method using a foaming agent, at 20 ° C., 500 to 3000 r, p,
The above-mentioned foaming treatment can usually be carried out by treating the foam to a viscosity of 150 to 1000 voids at a rotational speed of 1,000 m. Foaming agents include surfactants such as anionic ones such as ammonium stearate, ammonium lauryl sulfate, and potassium oleate soap, nonionic ones such as polyoxyethylene derivatives, and amphoteric ones such as lauryl betaine. is used. Although the foaming agent may be blended into the mixed emulsion, it is preferable to mix it into the acrylic polymer emulsion in advance. The appropriate amount is 0.1 to 15 parts by weight per 100 parts by weight of the acrylic polymer. In addition, as the stirrer, those commercially available under trade names such as OAKS mixer, fine form, and high mixer can be used.

The foamed mixed emulsion containing microbubbles is expanded and crosslinked in the presence of a crosslinking agent or an epoxy resin curing agent to form a crosslinked foam sheet.

The expansion is carried out on the liner while suppressing defoaming as much as possible.
It is appropriate to use a thickness of 1200 um. The liner has an appropriate affinity with the spreading layer, such as a stretched polyester film that has been given appropriate M release properties using a release agent, and can destroy the dense layer on the surface of the formed crosslinked foam sheet. A material that can be peeled off without any damage is used.

The crosslinking treatment of the spread layer is preferably carried out by a two-stage heat treatment method in which the layer is preheated at a temperature of about 100° C. or lower and then main heated. Main heating is usually carried out at a temperature sufficient for crosslinking treatment, for example 100℃.
It is carried out for 100-500 seconds at a temperature of ~200°C. The crosslinking agent is preferably blended in advance with the emulsion of the acrylic polymer, and the epoxy resin curing agent is also preferably blended in advance with the emulsion of the epoxy resin or the emulsion containing the acrylic resin. Known crosslinking agents such as melamine resins, epoxy resins, and polyisocyanates can be used.The appropriate amount is 0.1 to 50 parts by weight per 100 parts by weight of the acrylic polymer.

Regarding epoxy resin curing agents, dielenetriamine, triethylenetetramine, metaphenylenediamine,
Known compounds such as tris(dimethylaminomethyl)phenol can be used, and the amount thereof may be a normal amount.

The pressure-sensitive adhesive layer attached to one or both sides of the cross-linked foam sheet may be formed of a known pressure-sensitive adhesive such as a rubber-based or acrylic-based adhesive. The thickness is generally 1 to 500 μm, but is not limited to this and may be determined as appropriate depending on the purpose of use.

The obtained adhesive tape can be used for various purposes, especially for applications where shear tensile stress is applied to the adhesive tape, such as when adhering an adherend made of a hard plate-like material to a wall or the like. suitable for

Effects of the Invention According to the present invention, since a cross-linked foam sheet of an acrylic polymer containing an epoxy resin component and an acrylic resin component is used, it has excellent adhesive strength with the pressure-sensitive adhesive layer and can adhere to an adherend. It is possible to obtain an adhesive tape that can firmly adhere and maintain its adhesive state stably for a long period of time.

Further, according to the manufacturing method of the present invention, the adhesive tape described above can be obtained stably and efficiently.

Examples Example 1 An acrylic polymer with a solid content of 59% by weight obtained by emulsion polymerization of 63 parts (parts by weight, same hereinafter) of ethyl acrylate, 28 parts of butyl acrylate and 9 parts of acrylonitrile by a conventional method. The emulsion was blended with 15 parts of melamine resin, 21 parts of ammonium stearate, 2 parts of carboxylated ethyl acrylate, and 1 part of 25% by weight aqueous ammonia per 100 parts of the emulsion solids. Next, 15 parts of triethylenetetramine was added to 100 parts of bisphenol-based epoxy resin latex with a solid content of 55% by weight, and butyl acrylate/methyl methacrylate/acrylic acid: 90 parts
A mixed latex with 3.3 parts of acrylic resin latex having a solid content of 50% by weight and having a weight composition of /6.5/3.5 is added to the above-mentioned acrylic polymer emulsion, and polyethylene glycol is added to this. Add 0.5 part of octylphenyl ether and stir the resulting mixed emulsion with an oak mixer at 1000 r, p, m, , 2
A mixed emulsion (viscosity: about 300 poise, 20°C) was obtained, in which the body density was about 2.5 times larger due to the inclusion of microbubbles.

Next, the mixed emulsion containing microbubbles was extrusion coated on a biaxially stretched polyester film whose affinity had been appropriately adjusted using a die coater, and the formed spread layer with a thickness of 150 um was first coated at 80°C for 30 minutes. After preheating for 15 seconds,
Main heating was performed at 0° C. for 180 seconds to obtain a crosslinked foam sheet with a thickness of 150 mm.

Next, we used an acrylic pressure-sensitive adhesive made by blending polyisocyanate with butyl acrylate/acrylic acid copolymer.
First, the exposed surface of the cross-linked foam sheet is coated with a thickness of 60 mm, and a kraft paper-based double-sided release paper is pasted on the coated surface.The biaxially oriented polyester film attached to the cross-linked foam sheet is peeled off and rolled. A pressure-sensitive adhesive layer was provided on the newly exposed crosslinked foam sheet surface in the same manner as described above to obtain an adhesive tape having pressure-sensitive adhesive layers on both sides.

Example 2 An adhesive tape was obtained according to Example 1 except that the amount of acrylic resin latex in the mixed latex was 33 parts.

Example 3 An adhesive tape was obtained according to Example 1 except that the amount of acrylic resin latex in the mixed latex was 55 parts.

Comparative Example An adhesive tape was obtained according to Example 1 without using acrylic resin latex.

Evaluation Test The adhesive tapes obtained in Examples and Comparative Examples were subjected to the following tests.

[Adhesive strength] Width 20M1 thickness 0.2+am stainless steel plate (SUS3
04 BA finish) with adhesive tape between the ends of 20
Adhesion was performed using an adhesive area of part m +
300mm for 7 minutes at 20°C) to measure the breaking strength.
The shear adhesive strength was investigated.

[Holding force] An aluminum plate is adhered to a Bakelite plate via adhesive tape with an adhesive area of 10 m x 20 ay+, a load of 1 kg is applied to the aluminum plate, and the time taken for the aluminum plate to fall is measured by hanging this. did.

The results are shown in the table.

From the table, it can be seen that the adhesive tape of the present invention has excellent shear adhesive strength and good persistence of adhesive state.

Patent applicant: Nitto Electric Industry Co., Ltd.

Claims (1)

[Claims] 1. A pressure-sensitive adhesive layer is provided on one or both sides of a cross-linked foam sheet, and the cross-linked foam sheet contains an acrylic polymer component whose main monomer is an acrylic acid alkyl ester and an epoxy-based adhesive layer. It consists of a resin component and an acrylic resin component, and the total amount of the epoxy resin component and acrylic resin component is 1 to 20 parts by weight per 100 parts by weight of the acrylic polymer.
An adhesive tape comprising 0 parts by weight of the acrylic resin component and 0.1 to 4 times the weight of the epoxy resin component. 2. An emulsion containing 100 parts by weight of an acrylic polymer whose main monomer is an acrylic acid alkyl ester, and a total of 1 to 200 parts by weight of an epoxy resin and an acrylic resin, and the content of the acrylic resin. A mixed emulsion prepared by mixing an emulsion with an amount of 0.1 to 4 times the weight of the epoxy resin is foamed and then developed, and the developed layer is placed in the presence of a crosslinking agent or an epoxy resin curing agent. 2. The method for producing an adhesive tape according to claim 1, wherein a pressure-sensitive adhesive layer is attached to one or both sides of the crosslinked foam sheet formed by crosslinking treatment.