Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Adhesive outermost layer
Reexamination Certificate
1997-09-15
2001-04-17
Copenheaver, Blaine (Department: 1771)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Adhesive outermost layer
C428S041500, C428S3550RA, C528S272000
Reexamination Certificate
active
06218006
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a pressure-sensitive adhesive composition which is non-pressure-sensitive adhesive or low pressure-sensitive adhesive (tack free) at room temperature, pressure-sensitive adhesive sheets made up of the foregoing composition in the states of a sheet form, a tape form, etc., and a sealing material, a reinforcing sheet, and a pressure-sensitive adhesive sheet for printing using them.
BACKGROUND ART
A pressure-sensitive adhesive usually has a storage elastic modulus [G′] at room temperature of about 1×10
6
dyne/cm
2
or lower as described in D. Satas, Adhesive Age, 31(9), 28(1988). When the storage elastic modulus of a pressure-sensitive adhesive at room temperature is increased, the pressure-sensitive adhesive becomes too hard and becomes non-adhesive. This is because a micro-contact of the pressure-sensitive adhesive and the adherend is not sufficiently carried out in the adhesive step as in a wrapping film for foods, namely, the wrapping films are visually (optically) adhered to each other, but the adhesion is not exhibited.
However, because a conventional pressure-sensitive adhesive has a softness in a sticky state having a tackiness, the pressure-sensitive adhesive adheres quickly. But, it is not easy to peel the pressure-sensitive adhesive adhered by lightly contacting, and thus, the correction of the position is difficult. Also, in processing such as cutting, punching, etc., of a pressure-sensitive adhesive sheet, there is a problem that the processing edge is stained with the pressure-sensitive adhesive.
If the storage elastic modulus of the pressure-sensitive adhesive is increased to solve these problems, the adhesive property is lowered along with the tackiness as described above, and thus the adhesion to an adherend is difficult without an adhesive assisting means such as heat treatment.
As described above, a pressure-sensitive adhesive which has a high elasticity and non-pressure-sensitive adhesion or low pressure-sensitive adhesion (tack free) capable of preventing lowering of adhesive workability, etc., and also is excellent in the adhesion has not yet been found.
Under such circumstances, an object of the present invention is to provide a pressure-sensitive adhesive composition which shows an excellent adhesion while exhibiting a high elasticity and tack free at about room temperature, and hence can cope with the adhesive workability and the adhesion, and a pressure-sensitive adhesive sheet having the composition.
Also, other object of the present invention is to provide the above-described pressure-sensitive adhesive composition and pressure-sensitive adhesive sheets using the composition, which are excellent in the durability, the heat resistance, etc., and further to provide the above-described pressure-sensitive adhesive composition and pressure-sensitive adhesive sheets using the composition, which are also excellent in the self-adhesion in addition to the durability such as the heat resistance, weather resistance, etc.
Other object of the present invention is to provide the above-described pressure-sensitive adhesive composition and pressure-sensitive adhesive sheets using the composition, which show a good adhesion to various adherends and are excellent in the creep characteristics and the long-term durability and also is to provide the above-described pressure-sensitive adhesive composition and pressure-sensitive adhesive sheets using the composition, which satisfy the creep resistance and the adhesion in a high temperature range and are excellent in the shock resistance in a low-temperature range.
Furthermore, still other object of the present invention is to provide the above-described pressure-sensitive adhesive sheets using a release liner not subjected to a silicone release coating and thus suitable for computer instruments which are liable to cause problems by the existence of a silicone, and in particular to provide the above-described pressure-sensitive adhesive sheets which are excellent in the releasing property of the above-described liner and show a good adhesive strength.
Also, other object of the present invention is to provide pressure-sensitive adhesive sheets which can be wound in a roll form without using a release liner and are suitable for the uses such as computer instruments as pressure-sensitive adhesive sheets containing substantially no silicone compound.
DISCLOSURE OF THE INVENTION
The present inventors have discovered that by selecting a specific polymer for constituting a pressure-sensitive adhesive and crosslinking the polymer, a pressure-sensitive adhesive composition having specific values of the storage elastic modulus and the adhesive strength at room temperature can be obtained and the pressure-sensitive adhesive composition shows a good adhesion while having a high elasticity and being tack free, and also have discovered that a pressure-sensitive adhesive composition excellent in the self-adhesion in addition to the durability such as heat resistance and weather resistance can be obtained by specifying the solvent insoluble component of the polymer.
That is, the present invention provides a pressure-sensitive composition wherein the storage elastic modulus [G′] at room temperature is at least 2×10
6
dyne/cm
2
and the adhesive strength at room temperature is at least 1 kg/20 mm width, in particular, a pressure-sensitive composition comprising a polymer having a polycarbonate structure having a repeating unit represented by the following formula
wherein R represents a straight chain or branched hydrocarbon group having from 2 to 20 carbon atoms, as the polymer for constituting the pressure-sensitive adhesive composition, and particularly, a pressure-sensitive adhesive composition comprising a polyester having a weight average molecular weight of at least 10,000 synthesized from diol components indispensably containing polycarbonate diol and dicarboxylic acid components indispensably containing a dicarboxylic acid having an aliphatic hydrocarbon group having from 2 to 20 carbon atoms or an alicyclic hydrocarbon group as the molecular structure. Also, according to the present invention, there is further provided a pressure-sensitive adhesive composition having the above-described construction, wherein the solvent insoluble component is from 1 to 30% by weight and the self-adhesive strength is at least 2.0 kg/20 mm width.
Also, the present inventors have discovered that by combining the polymer having the polycarbonate structure described above and a specific acrylic polymer, a pressure-sensitive adhesive composition showing good adhesion characteristics to various adherends and being excellent in the creep characteristics and the long-term durability can be obtained. That is, according to other aspect of the present invention, there is provided a pressure-sensitive adhesive composition comprising, along with the polymer having the polycarbonate structure, an acrylic polymer having a glass transition temperature of not higher than −10° C. in an amount of from 10 to 90% by weight of the sum total of the above-described polymer and the acrylic polymer.
Furthermore, the present inventors have discovered that by combining the polymer having the polycarbonate structure described above and a specific resin, a pressure-sensitive adhesive composition satisfying the creep resistance and the adhesion in a high-temperature range and being excellent in the shock resistance at a low temperature can be obtained. That is, according to still other aspect of the present invention, there is provided a pressure-sensitive adhesive composition comprising, along with the polymer having the polycarbonate structure, a resin having a softening point of at least 80° C. in an amount of from 10 to 50% by weight of the sum total of the above-described polymer and the resin.
Moreover, the present invention can further provide pressure-sensitive adhesive sheets having the above-described pressure-sensitive adhesive compositions of various constitutions forme
Ando Masahiko
Hikosaka Waka
Kojima Makoto
Kouno Shin-ichi
Kume Katsuya
Copenheaver Blaine
Nitto Denko Corporation
Ruddock Ula C.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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