Nitto-denko Corporation

Akiko Takahashi

Hiroshi Wada

Tomonari Naito

Kenichi Okada

Mami Ikeya

Toshihide Suzuki

Kenichi Yamamoto

Yutaka Tosaki

Michio Umeda

Mitsuyoshi Shirai

Naofumi Kosaka

Naoyuki Nishiyama

Shouhei Wada

Keisuke Shimokita

Hironao Ootake

Kazuyuki Yagura

Mizuho Chiba

Asami Doi

Eriko Funatsu

Kai Okahara

A separator containing a substrate and a release layer formed on at least one side of the substrate wherein the separator shows a strain of not more than 7% when a load of 5N/20 mm is applied for one minute in the pulling direction, and when the substrate is cut in half in the thickness direction to divide the separator into two, an apparent elastic modulus in the pulling direction of one of the divided separators is larger than an apparent elastic modulus in the pulling direction of the other divided separator.

Separator

Provided are a double-sided PSA sheet comprising a PSA layer formed by directly applying an aqueous dispersion-type PSA composition to a non-woven fabric substrate, wherein the layer has a highly smooth surface; and a method for producing the same. In this method, an aqueous dispersion-type PSA composition is applied to at least a first side of the non-woven fabric substrate and the composition is allowed to dry to form a PSA layer. A non-woven fabric of 15 &#x3bc;m to 70 &#x3bc;m in thickness, 0.3 to 0.6 g/cmin bulk density, and 0.7 sec to 2 sec in air resistance (Gurley) when measured for 8 layers the non-woven fabric substrate is used as the non-woven fabric substrate.

Double-sided pressure-sensitive adhesive sheet and method for producing the same

A method is provided for producing a double-sided pressure-sensitive adhesive (PSA) sheet of a nonwoven fabric substrate, whereby the inherent performance of the PSA is more fully exploited using an aqueous dispersion-type PSA composition. This method comprises preparing an aqueous dispersion-type PSA composition and a nonwoven fabric substrate serving as a support. The method also comprises forming PSA layers which impregnate the substrate and which are obtained by drying the composition. These PSA layers impregnate the substrate so that the area of gaps observed in a vertical cross-section perpendicular to the machine direction of the substrate is about 500 &#x3bc;m/400 &#x3bc;m or less.

Method for producing double-sided pressure-sensitive adhesive sheet

Provided are a pressure-sensitive adhesive (PSA) sheet having excellent foam repulsion resistance and an aqueous PSA composition suitable for preparing this sheet. The composition primarily comprises an acrylic polymer obtained by polymerizing a starting monomer material containing an alkyl(meth)acrylate as a main monomer and both acrylic acid and methacrylic acid. The acrylic polymer preferably has a weight average molecular weight of 65&#xd7;10to 100&#xd7;10. The starting monomer material is preferred to further contain a silanol-forming monomer and polymerized without the silanol-forming monomer to produce a polymer having a gel fraction of 7 to 17 mass %. The post-crosslink PSA preferably has a gel fraction of 20 to 55 mass %.

Aqueous pressure-sensitive adhesive composition and utilization thereof

A pressure-sensitive adhesive sheet contains at least a pressure-sensitive adhesive layer containing an acrylic pressure-sensitive adhesive containing an acrylic polymer composition containing an acrylic polymer as a main component and a tackifier containing a tackifying resin as a main component, wherein reflection rate and attached amount in the fogging test in accordance with German Industrial Standard DIN 75201 are 70% or more and 2.0 mg or less, respectively. In the acrylic pressure-sensitive adhesive which forms the pressure-sensitive adhesive layer, a ratio of components having a molecular weight of 300 or less is preferably 4.2% by weight or less based on the total amount of solid matter of the acrylic pressure-sensitive adhesive. Furthermore, in the tackifying resin in the tackifier, a ratio of components having a molecular weight of 300 or less is suitably 4.2% by weight or less based on the total amount of solid matter of the tackifying resin.

Pressure-sensitive adhesive sheet

The present invention provides a water-dispersed acrylic PSA composition suitable for forming a PSA sheet. The PSA composition contains 100 parts by weight of an acrylic copolymer with a Tg of &#x2212;70&#xb0; C. to &#x2212;50&#xb0; C. obtained by polymerization of a monomer starting material containing 60 wt % or more of an alkyl (meth)acrylate with a Calkyl group and 5 wt % or less of a radical polymerizable monomer with a carboxyl group. When an adhesive sheet is formed therefrom, it exhibits an average SUS adhesive strength of 11 N/20 mm or greater, PP adhesive strength of 8.5 N/20 mm or greater, 80&#xb0; C. hold time of 1 hour or longer, and gap height of 10 mm or less in a curved surface adhesion test.

Pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet

An adhesive sheet is provided in which properties that cause corrosion of a non-contacting metal are inhibited. The adhesive sheet is provided with a pressure-sensitive adhesive layer formed from an aqueous dispersion type adhesive composition. The pressure-sensitive adhesive composition contains an aqueous dispersion type acrylic polymer synthesized using a chain transfer agent that does not have sulfur as a composite element thereof. The amount of sulfur-containing gas (as SO) released from the pressure-sensitive adhesive sheet in the case of heating for 1 hour at 85&#xb0; C. is 0.043 &#x3bc;g/1 cmor less, adhesive strength on an ABS sheet is 10 N/20 mm or more, and holding time as determined in an 80&#xb0; C. cohesive strength test is 1 hour or more.

A pressure-sensitive adhesive sheet has a high adhesiveness and an excellent terminal peeling resistance as well as exhibits extremely small diffusing amounts of formaldehyde and toluene. The pressure-sensitive adhesive sheet contains at least a pressure-sensitive adhesive layer of a water-dispersion type acrylic pressure-sensitive adhesive containing a water-dispersion type acrylic polymer and a tackifying resin-containing emulsion, wherein a diffusing amount of formaldehyde is less than 3 &#x3bc;g/mand a diffusing amount of toluene is 10 &#x3bc;g/g or less. As the tackifying resin-containing emulsion, a tackifying resin-containing emulsion prepared using substantially no organic solvents or a tackifying resin-containing emulsion prepared using a material other than aromatic hydrocarbon-based organic solvents can be suitably employed.

The present invention provides a water-dispersed acrylic PSA composition suitable for forming a PSA sheet. The PSA composition contains 0.5 to 15 parts by weight of an acrylic copolymer (polymer H) with a Tg of 30&#xb0; C. to 120&#xb0; C. in relation to 100 parts by weight of an acrylic copolymer (polymer L) with a Tg of &#x2212;70&#xb0; C. to &#x2212;50&#xb0; C. The polymer L is obtained by polymerization of a monomer starting material comprising 60 wt % or more of an alkyl (meth)acrylate with a C-Calkyl group; and 0.5 to 10 wt % of a radical polymerizable monomer with a carboxyl group.

Pressure-sensitive adhesive composition and use thereof

There provided a pressure-sensitive adhesive (PSA) composition constituting a PSA layer, which may exhibit a plurality of properties in a well-balanced manner, and a PSA sheet including the PSA layer. The composition is an aqueous PSA composition in which an acrylic polymer serves as a main component and the acrylic polymer is dispersed in water, and contains: A) acrylic polymer obtained by polymerizing a monomer raw material including alkyl(meth)acrylate as a main monomer, a first functional monomer having a first functional group to react with a hydrazino group, and a second functional monomer having a second functional group to react with a carbodiimide group; B) a hydrazine-based crosslinking agent; and C) a carbodiimide-based crosslinking agent.

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Ibaraki, Japan

Akiko Takahashi