Acrylic pressure-sensitive adhesive composition and pressure-sensitive adhesive tape

Abstract

The present invention relates to an acrylic pressure-sensitive adhesive composition containing an acrylic polymer and a tackifier obtained by acid modification of a tackifier resin inherently free of an acid component; a pressure-sensitive adhesive tape including a substrate made of a film comprising an olefin polymer or a thermoplastic resin containing a carbonyl oxygen atom in the molecular skeleton, and the acrylic pressure-sensitive adhesive composition on at least one surface of the substrate, and the like. The invention provides an acrylic pressure-sensitive adhesive composition having high adhesive strength (particularly initial adhesive strength) to an adherend having lower polarity, such as an olefin polymer heretofore been considered poorly adhesive, wherein degradation of the adhesive strength after heating and preservation has been suppressed, as well as a pressure-sensitive adhesive tape comprising the composition. The pressure-sensitive adhesive tape of the present invention is also useful for binding.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a pressure-sensitive adhesive composition (hereinafter to be also referred to as a pressure-sensitive adhesive) and a pressure-sensitive adhesive tape. More particularly, this invention relates to an acrylic pressure-sensitive adhesive composition, which has high adhesive strength (particularly initial adhesive strength) to an adherend having poor polarity, such as olefin polymer and the like, and which retains adhesive strength even after heating and preservation (or retains adhesive strength even after lapse of time after heating, particularly adhesive strength to a backside of the adhesive tape (i.e., substrate surface free of adhesive of the adhesive tape)), as well as a pressure-sensitive adhesive tape having a certain elongation degree upon unwinding, applicable to binding purposes and free of peeling off of the tape end after winding. BACKGROUND OF THE INVENTION [0002] For example, for a pressure-sensitive adhesiv...

AI Technical Summary

Benefits of technology

The present invention provides an acrylic pressure-sensitive adhesive composition and a pressure-sensitive adhesive tape that have high initial adhesive strength to poorly polar materials such as olefin polymers and thermoplastic resins containing carbonyl oxygen atoms in the molecular skeleton. The adhesive composition and tape also have superior properties such as preventing loose binding of wires and wrinkles on the tape, and difficult peeling of tape end after binding. The composition contains an acrylic polymer and a tackifier obtained by acid modification of a tackifier resin. The tackifier has a weight-average molecular weight of 1000-66000 and an acid value of 5-100 mg KOH / g. The composition is substantially free of halogen atoms. The pressure-sensitive adhesive tape has a substrate made of a film comprising an olefin polymer or thermoplastic resin containing a carbonyl oxygen atom in the molecular skeleton, and the adhesive composition. The tape can be used for binding and has an elongation degree of 2-60% and a peeled end portion of 0-1.0 mm.

Problems solved by technology

However, incineration of PVC may produce toxic gases such as dioxins, chlorine gas and the like.

When a rubber pressure-sensitive adhesive is used, however, adhesive strength to a substrate or adherend made of an olefin polymer becomes too strong, which poses problems for a pressure-sensitive adhesive tape, such as unattainable unwinding of a tape, and the like.

Upon unwinding, the tape often suffers from stretched substrate, broken substrate and the like.

When a rubber pressure-sensitive adhesive is used for an adherend made of an olefin polymer, problems occur due to its excessive adhesive strength, as evidenced by a remainder of the adhesive on an adherend upon peeling off (i.e., adhesive residue), and the like.

When an acrylic pressure-sensitive adhesive is selected, problems occur such as weak adhesive strength to the surface of a substrate or adherend having poor polarity, such as olefin polymer and the like, and the like.

For example, in the case of a binding tape, the unwinding force of the tape and the fastening force thereof are both weak, thus failing to achieve sufficient winding.

In addition, since the adhesive strength to the substrate (backside thereof) is weak, the tape end may defectively peel off after winding the tape and the like.

However, it has been elucidated that, even if such improvement is made, a tape, wherein the substrate is an olefin polymer and the adhesive is an acrylic pressure-sensitive adhesive, tends to show weaker backside adhesive strength after heating and preservation, and weaker adhesive strength after adhesion to an olefin polymer adherend, heating and preservation, peeling off and adhesion again to the olefin polymer adherend, as compared to the initial adhesive strength.

In addition, there have been problems of degraded unwinding force and easy occurrence of end peeling.

Particularly when these olefin polymers are used, degradation of the adhesive strength after heating and preservation is significant.

When the amount of the tackifier increases, the cohesive strength of the adhesive becomes lower, which in turn problematically causes a cohesive failure upon peeling and the like.

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