JP2005179412A - Tape-like insulating material, insulated article and pressure-sensitive adhesive tape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tape-like insulating material having good insulation characteristics without leaving a pressure-sensitive adhesive on an adherend after peeling and further an excellent appearance without bubbles, to provide an insulated article in which the tape-like insulating material is laminated and to provide a pressure-sensitive adhesive tape having a water dispersed type pressure-sensitive adhesive layer provided on one or both surfaces of a substrate. <P>SOLUTION: The tape-like insulating material is provided with the pressure-sensitive adhesive layer on one or both surfaces of the insulating substrate. In the tape-like insulating material, the pressure-sensitive adhesive layer is formed of a water-dispersed type acrylic pressure-sensitive adhesive containing a copolymer emulsion obtained by carrying out emulsion polymerization of a monomer component consisting essentially of an alkyl (meth)acrylate in which the number of carbon atoms of the alkyl group is 4-12 and containing a carboxyl group-containing monomer in the presence of an emulsifying agent. An undercoating layer formed of an undercoating agent composed of a water-soluble polymer or an aqueous emulsion containing an oxazoline group is provided between the insulating substrate and the pressure-sensitive adhesive layer. The arithmetic mean height (Ra) of the insulating substrate surface coming into contact with the undercoating layer is ≤2.0 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a tape-shaped insulating material using a water-dispersed acrylic pressure-sensitive adhesive and an insulating article on which the tape-shaped insulating material is bonded. The tape-shaped insulating material of the present invention is used for interlayer insulation and outer surface insulation of electrical parts such as transformers and coils, and electronic parts, and these articles are used as insulating articles. Moreover, this invention relates to the pressure sensitive adhesive tape using the said adhesive.

  Conventionally, as a pressure-sensitive adhesive used for a tape-shaped insulating material, an acrylic or rubber-based solvent-based pressure-sensitive adhesive having excellent insulating properties has been used. Solvent removal is an important issue for adhesives used in such tape-shaped insulating materials because of the social demands for environmental protection, resource saving, health and safety, and stricter regulations, as in the case of general adhesives. Therefore, an alternative to the solvent-type pressure-sensitive adhesive is desired. As an adhesive that replaces the solvent-type adhesive, a water-dispersed adhesive is considered to be superior to a hot-melt adhesive or a curable adhesive because of its versatility and possibility of application development.

  The acrylic water-dispersible pressure-sensitive adhesive includes a polymer emulsion obtained by polymerizing a monomer mainly composed of (meth) acrylic acid alkyl ester in the presence of an emulsifier. In order to apply an acrylic water-dispersed pressure-sensitive adhesive to a film substrate, it is necessary to corona-treat the coated surface in advance in terms of anchoring properties. Solvent-type acrylic adhesives generally have good anchoring properties even without corona treatment.

  However, in the case of an acrylic water-dispersed pressure-sensitive adhesive, sufficient anchorage cannot be obtained by a method such as a known corona treatment, and when the roll-shaped tape is rewound, the pressure-sensitive adhesive is transferred to the back surface, In addition, when the adhesive strength with the adherend is high, there is a problem that the adhesive remains on the adherend when the tape is peeled off. In such a case, if a solvent-type primer is used, good anchoring properties can be obtained, but this is contrary to the environmentally conscious design concept of using a water-dispersed acrylic pressure-sensitive adhesive as the pressure-sensitive adhesive.

  A technique for forming a primer layer on an adhesive tape using an acrylic polymer as a base material and an acrylic adhesive as an adhesive layer (Patent Document 1), or forming a primer layer on an adherend on which an adhesive sheet (adhesive sheet) is pressure-bonded Although the coating composition (patent document 2) to make is known, the primer suitable for the adhesive tape which apply | coated the water dispersion type acrylic adhesive to the various base material is not known.

On the other hand, when an acrylic water-dispersed pressure-sensitive adhesive is applied to a film substrate, air is easily trapped between the coating film and the substrate, and after drying, air bubbles are formed at the interface between the substrate and the pressure-sensitive adhesive layer. It also had the problem of generating. The generation of bubbles is not preferable because it causes poor appearance, poor insulation characteristics, and poor throwing performance.
JP-A-7-133467 JP 2000-109754 A

  An object of the present invention is to provide a tape-like insulating material that has good insulating properties, no adhesive remains on an adherend after peeling, and is excellent in appearance without bubbles. Another object of the present invention is to provide an insulating article to which a tape-like insulating material is bonded. Another object of the present invention is to provide a pressure-sensitive adhesive tape in which a pressure-sensitive adhesive layer made of a water-dispersed pressure-sensitive adhesive is provided on one side or both sides of a substrate.

  As a result of intensive studies to solve the above problems, the present inventors have used the following as a primer, and set the surface roughness of the insulating substrate in contact with the primer to a specific range, thereby achieving the above object. The inventors have found that this can be achieved and have completed the present invention.

That is, the present invention is a tape-like insulating material provided with an adhesive layer on one side or both sides of an insulating substrate,
The pressure-sensitive adhesive layer is emulsified in the presence of an emulsifier in the presence of an emulsifier, the main component of the alkyl group is a (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms and a carboxyl group-containing monomer. It is formed with a water-dispersed acrylic pressure-sensitive adhesive containing a copolymer emulsion obtained by polymerization,
Between the insulating base material and the pressure-sensitive adhesive layer, there is provided an undercoat layer formed of an undercoat composed of a water-soluble polymer or water-based emulsion containing an oxazoline group, and the insulating material in contact with the undercoat layer The arithmetic average height (Ra) of the substrate surface is 2.0 μm or less.

  The tape-shaped insulating material of the present invention uses the water-dispersed acrylic pressure-sensitive adhesive as a water-dispersed pressure-sensitive adhesive, and contains a large amount of an ionic emulsifier such as natural rubber latex or synthetic rubber latex pressure-sensitive adhesive. There is no deterioration in insulation characteristics. In addition, by having the undercoat layer as described above between the insulating substrate and the pressure-sensitive adhesive layer, the adhesion between the insulating substrate and the pressure-sensitive adhesive layer is improved, and the pressure-sensitive adhesive layer remains on the adherend after peeling. It is a tape-shaped insulating material that expresses the effect of not. Furthermore, by making the arithmetic average height of the surface of the insulating base material in contact with the undercoat layer 2.0 μm or less, the wettability of the coating film with respect to the insulating base material can be improved, and air entrapment is effectively suppressed. Can do. Therefore, no bubbles are generated in the formed undercoat layer. Furthermore, the undercoat made of a water-soluble polymer or water-based emulsion containing an oxazoline group used as a material for forming the undercoat layer has good wettability with the water-dispersed acrylic pressure-sensitive adhesive. Air is less likely to bite between the coating film made of the acrylic pressure-sensitive adhesive, and even when air is bitten, it can be easily discharged outside. Therefore, no bubbles are generated in the formed pressure-sensitive adhesive layer, and a tape-like insulating material having excellent insulating properties, appearance, and anchoring properties can be obtained.

  The undercoat is preferably an acrylic emulsion containing an oxazoline group. By selecting the emulsion, the anchoring property when applying the primer to the insulating base material is further improved, and the adhesive property can be maintained well. Moreover, since the wettability with the water-dispersed acrylic pressure-sensitive adhesive is further improved, the generation of bubbles can be further suppressed.

  The thickness of the undercoat layer is preferably 0.03 to 4.0 μm, and more preferably 0.05 to 2.0 μm. If it is the thickness of this range, generation | occurrence | production of a bubble can be suppressed and anchoring property and adhesiveness can fully be exhibited.

  The present invention also relates to an insulating article on which the tape-like insulating material is bonded.

On the other hand, another present invention is a pressure-sensitive adhesive tape provided with a pressure-sensitive adhesive layer on one side or both sides of a substrate,
The pressure-sensitive adhesive layer is emulsified in the presence of an emulsifier in the presence of an emulsifier, the main component of the alkyl group is a (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms and a carboxyl group-containing monomer. It is formed with a water-dispersed acrylic pressure-sensitive adhesive containing a copolymer emulsion obtained by polymerization,
Between the base material and the pressure-sensitive adhesive layer, there is provided an undercoat layer formed of an undercoat made of a water-soluble polymer or an aqueous emulsion containing an oxazoline group, and the base material in contact with the undercoat layer The present invention relates to a pressure-sensitive adhesive tape having a surface arithmetic average height (Ra) of 2.0 μm or less.

  The characteristics and the like of the pressure-sensitive adhesive tape having the above configuration are substantially the same as the characteristics and the like of the tape-shaped insulating material.

  The undercoat is preferably an acrylic emulsion containing an oxazoline group. The reason is the same as above.

  Further, the thickness of the undercoat layer is preferably 0.03 to 4.0 μm, and more preferably 0.05 to 2.0 μm. The reason is the same as above.

  The water-dispersed acrylic pressure-sensitive adhesive that forms the pressure-sensitive adhesive layer in the tape-shaped insulating material of the present invention is mainly composed of a (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms in the alkyl group and a carboxyl group-containing single-layer. It contains a copolymer emulsion obtained by emulsion polymerization of a monomer component containing a monomer in the presence of an emulsifier.

  The alkyl group having 4 to 12 carbon atoms in the (meth) acrylic acid alkyl ester is an ester of acrylic acid or methacrylic acid and an alcohol having 4 to 12 carbon atoms, specifically, (meth) acrylic acid. Butyl, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, etc. Among these, one or more of them are used. These (meth) acrylic acid alkyl esters are used in a proportion of 50% by weight or more, preferably 80% by weight or more, more preferably 90 to 99.5% by weight in the monomer component as the main component of the monomer. . When the ratio of the (meth) acrylic acid alkyl ester is small, it tends to be difficult to obtain a good adhesive pressure-sensitive adhesive.

  In addition to the above (meth) acrylic acid alkyl ester, the monomer component is used to improve the adhesion to the adherend or to introduce a crosslinking point for post-crosslinking the resulting copolymer. Furthermore, in order to increase the cohesive strength of the pressure-sensitive adhesive and to improve the mechanical stability by neutralization, as a functional group-containing monomer copolymerizable with the above (meth) acrylic acid alkyl ester, carboxyl Contains a group-containing monomer. Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, itaconic acid, maleic acid, and crotonic acid. The carboxyl group-containing monomer is usually used so that the total of the alkyl group and the (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms is 100% by weight as a monomer component. The carboxyl group-containing monomer is preferably used in a proportion of 50% by weight or less, more preferably 20% by weight or less, and particularly preferably 0.5 to 10% by weight.

  In order to improve the adhesion to the adherend, or to introduce a crosslinking point for post-crosslinking the resulting copolymer, and further to increase the cohesive strength of the pressure-sensitive adhesive, An appropriate amount of other functional group-containing monomer or modifying monomer other than those described above may be used. These other functional group-containing monomers include (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms in the alkyl group and the carboxyl group-containing monomer satisfying the above ratio, and A total of 100% by weight is used as a monomer component in total with the monomer. These are usually used at a ratio of 50% by weight or less, preferably 20% by weight or less, more preferably 0.5 to 10% by weight.

  Other functional group-containing monomers include hydroxyl-containing monomers such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (meth ) Amide group-containing monomers such as acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, (meth) Amino group-containing monomers such as 2- (N, N-dimethylamino) ethyl acrylate, glycidyl group-containing monomers such as glycidyl (meth) acrylate, propyltrimethoxysilane (meth) acrylate, (meth) Various governments such as propyldimethoxysilane acrylate, propyltriethoxysilane (meth) acrylate Alkoxysilane, (meth) acrylonitrile, N- (meth) acryloyl morpholine, N- vinyl-2-pyrrolidone. These functional group-containing monomers can be used alone or in combination of two or more.

  Other modifying monomers include (meth) acrylic acid alkyl esters having 1 to 3 carbon atoms in the alkyl group, such as methyl (meth) acrylate, ethyl (meth) acrylate, and isopropyl (meth) acrylate. And (meth) acrylic acid triester, (meth) acrylic acid stearyl (meth) acrylic acid alkyl group having 13 to 18 carbon atoms (meth) acrylic acid alkyl ester, vinyl acetate, styrene, vinyltoluene and the like. Also, neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate, propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, dipentaerythritol hexa ( Examples thereof include those having two or more polymerizable functional groups such as (meth) acrylate. These modifying monomers can also be used alone or in combination of two or more.

  As the emulsifier, anionic emulsifiers and nonionic emulsifiers used in emulsion polymerization can be used without particular limitation. For example, anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, etc. Nonionic emulsifiers and the like.

  The amount of the emulsifier used is not particularly limited, but is about 0.3 to 5 parts by weight with respect to 100 parts by weight of the monomer component in order to suppress a decrease in insulation characteristics due to containing a large amount of the ionic emulsifier. Is preferable. When the amount of the emulsifier used is increased, the amount of the water-soluble component in the pressure-sensitive adhesive layer formed by the water-dispersed acrylic pressure-sensitive adhesive containing the obtained copolymer emulsion increases, and the insulating properties tend to be lowered. Therefore, the amount of emulsifier used is preferably 3 parts by weight or less, more preferably 2 parts by weight or less. The amount of the emulsifier used is preferably 0.5 to 3 parts by weight, more preferably 0.7 to 2 parts by weight.

  Emulsion polymerization of the monomer component is performed by a conventional method using an appropriate polymerization initiator in the presence of the emulsifier to prepare an aqueous dispersion of an acrylic polymer. Emulsion polymerization is performed by general batch polymerization, continuous dropping polymerization, divided dropping polymerization, or the like. The polymerization temperature can be about 30 to 90 ° C.

  Examples of the polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis (N, N′-dimethyleneisobutyl). Amidines), persulfates such as potassium persulfate and ammonium persulfate, peroxides such as benzoyl peroxide and t-butyl hydroperoxide, and redox systems such as persulfate and sodium bisulfite Agents and the like. In emulsion polymerization, an appropriate chain transfer agent typified by mercaptans may be used as necessary for adjusting the molecular weight of the obtained copolymer.

  The water-dispersed acrylic pressure-sensitive adhesive used in the present invention can contain the above-mentioned polymer emulsion as a main component, and can contain a crosslinking agent as necessary. As the crosslinking agent, generally used ones such as an isocyanate crosslinking agent, an epoxy crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent, and a metal chelate crosslinking agent can be used. These crosslinking agents include a homopolymer contained in a polymer emulsion or a copolymer emulsion other than the effect of crosslinking by reacting with a functional group introduced into the polymer by using a functional group-containing monomer (for example, When a carboxyl group-containing monomer is used as the functional group-containing monomer, it is difficult for the carboxyl group-containing monomer to be copolymerized in the micelle of the emulsifier during emulsion polymerization. The reaction with a homopolymer or a copolymer close to a homopolymer) has an effect of reducing water-soluble components, and is preferably used. Thereby, there exists a reduction effect of the amount of water extraction components.

  The amount of the crosslinking agent to be used is not particularly limited, but is usually about 1: 0.5, preferably 1: 0.001 to 0 in terms of an equivalent ratio of the functional group introduced into the copolymer: the functional group of the crosslinking agent. .3 is preferable.

  Further, the water-dispersed acrylic pressure-sensitive adhesive used in the present invention can contain a tackifier component and other various additives. Examples of the tackifier component include rosin resins, terpene resins, aliphatic petroleum resins, aromatic petroleum resins, copolymer petroleum resins, alicyclic petroleum resins, xylene resins, and elastomers.

  The tape-shaped insulating material of the present invention is obtained by forming a pressure-sensitive adhesive layer on one side or both sides of an insulating base material with the water-dispersed acrylic pressure-sensitive adhesive. The pressure-sensitive adhesive layer is preferably adjusted so that the amount of the water extraction component is 3% by weight or less. In preparing the water-dispersed acrylic pressure-sensitive adhesive, in addition to the alkyl group (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms as the main component of the monomer, a carboxyl group-containing monomer or the like The type and addition amount of the functional group-containing monomer and the modifying monomer, the type and addition amount of the emulsifier, and the type and addition amount of the crosslinking agent added to the resulting copolymer are appropriately adjusted.

  The insulating substrate is not particularly limited. For example, in addition to plastic films such as polyester and polypropylene, paper and nonwoven fabric, heat-resistant polyimide, polyamide, polyacetate and the like, or a composite substrate of these, or in some cases, these And a base material impregnated with an epoxy resin or the like.

  On one side or both sides of the insulating substrate, a composition composed of an inorganic pigment and a binder may be printed and colored.

  In the present invention, an insulating substrate having an arithmetic average height (Ra) of 2.0 μm or less on the surface of the insulating substrate in contact with the undercoat layer is used. Preferably, the arithmetic average height (Ra) is 1.0 μm or less. By setting the arithmetic average height of the surface of the insulating base material in contact with the undercoat layer within the above range, the wettability of the coating film (undercoat agent) to the insulating base material can be improved. Therefore, the air between the coating film and the insulating substrate is easily discharged in a short time, and it is difficult to bite the air. As a result, it is considered that no bubbles are generated in the undercoat layer after drying. When the arithmetic average height (Ra) exceeds 2.0 μm, sufficient wettability cannot be obtained, so air is not discharged or air is easily trapped, and air bubbles are formed in the undercoat layer after drying. It tends to occur.

  The tape-shaped insulating material of the present invention is characterized by having an undercoat layer between the insulating base material and the pressure-sensitive adhesive layer.

  The undercoat used to form the undercoat layer is composed of a water-soluble polymer containing an oxazoline group or an aqueous emulsion. As the polymer, known polymers such as an acrylic polymer containing an oxazoline group in the side chain and an acrylic polymer such as a polystyrene-acrylonitrile copolymer containing an oxazoline group in the side chain can be used without limitation. A water-soluble type or water-based emulsion type of such a polymer is commercially available. Specific examples of the water-soluble polymer include “Epocross WS-500” and “Epocross WS-700” manufactured by Nippon Shokubai Co., Ltd. Examples of aqueous emulsions include “Epocross K-1000” series and “Epocross K-2000” series manufactured by Nippon Shokubai Co., Ltd. Of these, acrylic emulsions are preferred in that the water resistance of the undercoat layer after undercoating and drying is improved. This is because if the water resistance of the undercoat layer is good, the adhesive properties of the water-dispersible acrylic adhesive are further improved.

  An undercoat layer can be formed by directly applying and drying on one or both sides of the insulating base using the undercoat.

  The thickness of the undercoat layer after drying is preferably 0.03 to 4.0 μm, more preferably 0.05 to 2.0 μm.

  The pressure-sensitive adhesive layer can be formed by directly applying the water-dispersed acrylic pressure-sensitive adhesive to the surface of the undercoat layer and drying it. Alternatively, the pressure-sensitive adhesive layer formed on the separator in the same manner may be transferred onto the insulating base material having the undercoat layer.

  The thickness of the pressure-sensitive adhesive layer after drying is usually 10 to 50 μm, and preferably 20 to 40 μm. If it is the thickness of this range, the function as an adhesion layer which has adhesiveness and insulation can be exhibited.

  The tape-like insulating material of the present invention is obtained as a sheet-like or tape-like form by providing a single layer or a plurality of pressure-sensitive adhesive layers on one or both sides of an insulating substrate via an undercoat layer.

  The tape-like insulating material of the present invention is suitably used for various electronic components and is bonded to electronic components to constitute electronic components. The insulating article of the present invention includes such electronic parts. Specific examples thereof are not particularly limited, but examples include transformer interlayer insulation and exterior insulation.

  The pressure-sensitive adhesive tape of the present invention can also be used for general tape applications. The pressure-sensitive adhesive tape can be produced by the same material and method as the tape-like insulating material except that a general base material is used instead of the insulating base material.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. Parts mean parts by weight. The arithmetic average height (Ra) was measured in accordance with JIS B0601-2001.

Example 1
A reaction vessel equipped with a cooling tube, a nitrogen introducing tube, a thermometer and a stirring device was charged with 30 parts of water and 0.3 part of ammonium persulfate and purged with nitrogen for 1 hour under stirring. Here, 95 parts of 2-ethylhexyl acrylate, 5 parts of acrylic acid and 1.0 part of polyoxyethylene lauryl ether ammonium sulfate (trade name “HITENOL LA-16” of Daiichi Kogyo Seiyaku Co., Ltd.) as an emulsifier (in terms of solid content) ) Was emulsified with 70 parts of water at 80 ° C. over 3 hours, and further aged at 80 ° C. for 2 hours. Then, it cooled to room temperature and adjusted to pH8 with 10 weight% ammonia water, and obtained the copolymer emulsion. As a water-soluble crosslinking agent containing an oxazoline group, 100 parts by weight of the solid content (water-dispersed copolymer) of this copolymer emulsion is trade name “Epocross WS-700” (oxazoline group) of Nippon Shokubai Co., Ltd. Equivalent: 220 g · solid / eq.) 0. 1 part (in terms of solid content) was mixed to obtain a water-dispersed acrylic pressure-sensitive adhesive.

  Next, on one side (arithmetic average height: 0.11 μm) of a polyester film (25 μm thick), an oxazoline group-containing acrylic emulsion (trade name “Epocross K-2020E” of Nippon Shokubai Co., Ltd.) is dried. Was applied to a thickness of 0.05 μm and dried at 100 ° C. for 1 minute to obtain an insulating base material on which an undercoat layer was formed.

  Next, the water-dispersed acrylic pressure-sensitive adhesive is applied to the surface of the undercoat layer of the insulating base so that the thickness after drying becomes 30 μm, and dried at 100 ° C. for 3 minutes. Was made.

Example 2
A water-dispersed acrylic adhesive was prepared in the same manner as in Example 1 except that 95 parts of 2-ethylhexyl acrylate and 5 parts of acrylic acid were used, and 95 parts of n-butyl acrylate and 5 parts of methacrylic acid were used. Prepared.

  Next, one side of a polyester film (25 μm thick) was corona-treated, and a composition containing a blue inorganic pigment and an organic material binder was applied to the corona-treated surface by 1 μm. The arithmetic average height of the coated surface was 0.32 μm. Thereafter, an oxazoline group-containing acrylic emulsion (trade name “Epocross K-2010E” manufactured by Nippon Shokubai Co., Ltd.) was applied to the coated surface so that the thickness after drying was 1.0 μm. The insulating base material in which the undercoat layer was formed was obtained by drying for a minute.

  Next, the water-dispersed acrylic pressure-sensitive adhesive is applied to the surface of the undercoat layer of the insulating base so that the thickness after drying becomes 30 μm, and dried at 100 ° C. for 3 minutes. Was made.

Example 3
A water-dispersed acrylic adhesive was prepared in the same manner as in Example 1 except that 95 parts of 2-ethylhexyl acrylate and 5 parts of acrylic acid were used, and 95 parts of n-butyl acrylate and 5 parts of methacrylic acid were used. Prepared.

  Next, one side of the polyester film (25 μm thick) was corona-treated, and a composition containing a white inorganic pigment and an organic material binder was applied to the corona-treated surface by 6 μm. The arithmetic average height of the coated surface was 1.8 μm. Thereafter, an oxazoline group-containing acrylic emulsion (trade name “Epocross WS-700” of Nippon Shokubai Co., Ltd.) was applied to the coated surface so that the thickness after drying was 3.9 μm. The insulating base material in which the undercoat layer was formed was obtained by drying for a minute.

  Next, the water-dispersed acrylic pressure-sensitive adhesive is applied to the surface of the undercoat layer of the insulating base so that the thickness after drying becomes 30 μm, and dried at 100 ° C. for 3 minutes. Was made.

Comparative Example 1
In Example 1, a tape-like insulating material was produced in the same manner as in Example 1 except that the undercoat layer was not provided.

Comparative Example 2
In Example 2, a tape-like insulating material was produced in the same manner as in Example 2 except that the undercoat layer was not provided.

Comparative Example 3
In Example 3, a tape-shaped insulating material was produced in the same manner as in Example 3 except that the undercoat layer was not provided.

Comparative Example 4
In Example 1, a tape-shaped insulating material was produced in the same manner as in Example 1 except that a polyester film (thickness of 25 μm) having an arithmetic average height of 2.1 μm on the surface on which the undercoat layer was formed was used.

  About each tape-shaped insulating material obtained by the above Examples 1-3 and Comparative Examples 1-4, the presence or absence of a bubble, an electrolytic corrosion coefficient (insulation characteristic), anchoring property, and adhesive force was investigated with the following method. These results are shown in Table 1.

<Presence of bubbles>
It was visually confirmed whether or not bubbles were generated in the adhesive layer.

<Corrosion coefficient (insulation characteristics)>
The electrolytic corrosion coefficient was measured according to JIS C-2338, which describes a test method for a polyester film adhesive tape for electrical insulation.

<Throwing property>
Stainless steel plate No. After polishing with 360 sandpaper, a tape-like insulating material was bonded to a stainless steel plate according to JIS Z-0237 and heated at 80 ° C. for 1 hour. After cooling to room temperature, peeling was performed at a peeling speed of 30 m / min, and the area (%) of the adhesive residue was measured.

<Adhesive strength>
According to JIS Z-0237, a tape-like insulating material was bonded to a stainless steel plate, and the peeling force (180 degree peel, peeling speed 300 mm / min) was measured.

表１に示す通り、実施例のテープ状絶縁材は、粘着剤層に気泡が発生しておらず、外観性や投錨性や接着力に優れる。また、ＪＩＳ Ｃ−２３３８で規定される電食係数が０．９８以上であり、電食係数が良好で絶縁特性に優れている。

As shown in Table 1, the tape-shaped insulating materials of the examples are free from bubbles in the pressure-sensitive adhesive layer, and are excellent in appearance, anchoring properties and adhesive strength. Moreover, the electrolytic corrosion coefficient prescribed | regulated by JISC-2338 is 0.98 or more, an electrolytic corrosion coefficient is favorable, and it is excellent in the insulation characteristic.

Claims (7)

A tape-like insulating material provided with a pressure-sensitive adhesive layer on one or both sides of an insulating substrate, wherein the pressure-sensitive adhesive layer is mainly composed of (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms in the alkyl group, And a monomer component containing a carboxyl group-containing monomer, formed by a water-dispersed acrylic pressure-sensitive adhesive containing a copolymer emulsion obtained by emulsion polymerization in the presence of an emulsifier,
Between the insulating base material and the pressure-sensitive adhesive layer, there is provided an undercoat layer formed of an undercoat composed of a water-soluble polymer or water-based emulsion containing an oxazoline group, and the insulating material in contact with the undercoat layer A tape-shaped insulating material having an arithmetic average height (Ra) of a substrate surface of 2.0 µm or less. The tape-shaped insulating material according to claim 1, wherein the primer is an acrylic emulsion containing an oxazoline group. The tape-shaped insulating material according to claim 1 or 2, wherein the undercoat layer has a thickness of 0.03 to 4.0 µm. The insulation article by which the tape-shaped insulating material in any one of Claims 1-3 is bonded. A pressure-sensitive adhesive tape provided with a pressure-sensitive adhesive layer on one or both sides of a substrate,
The pressure-sensitive adhesive layer is emulsified in the presence of an emulsifier in the presence of an emulsifier, the main component of the alkyl group is a (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms and a carboxyl group-containing monomer. It is formed with a water-dispersed acrylic pressure-sensitive adhesive containing a copolymer emulsion obtained by polymerization,
Between the base material and the pressure-sensitive adhesive layer, there is provided an undercoat layer formed of an undercoat made of a water-soluble polymer or an aqueous emulsion containing an oxazoline group, and the base material in contact with the undercoat layer A pressure-sensitive adhesive tape having an arithmetic average surface height (Ra) of 2.0 μm or less. The pressure-sensitive adhesive tape according to claim 5, wherein the primer is an acrylic emulsion containing an oxazoline group. The pressure-sensitive adhesive tape according to claim 5 or 6, wherein the undercoat layer has a thickness of 0.03 to 4.0 µm.