JP2000265143A - Pressure-sensitive adhesive double coated tape for recycling molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure-sensitive adhesive double coated tape used for adhering component articles, such as plastic and foamed component articles, to molded articles, such as metal and plastic articles, preventing the pressure- sensitive adhesive mass from being left on the adherend, preventing itself from breaking or fracturing between substrate layers, and therefore having good release properties, when the pressure-sensitive adhesive double coated tape is released from the adherend with the aim of recycling the molded articles and the component articles. SOLUTION: This pressure-sensitive adhesive double coated tape comprises a nonwoven fabric, as a substrate, which has a thickness of 30-80 μm and is formed by mixing and weaving Manila hemp with rayon, or with pulp, in an amount of 10-50%, and rerelease type pressure-sensitive adhesive mass layers of which the each has a thickness of 50-90 μm, contains an acrylic ester copolymer having an weight-average molecular weight of 600,000 to 1,000,000 as a main component, and is applied to each side of the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is mainly used for bonding a molding material such as metal or plastic to a member such as plastic or foam. The present invention relates to a double-sided pressure-sensitive adhesive tape which does not leave an adhesive on an adherend when the tape is peeled off, does not break between the support layers, and does not break the tape.

[0002]

2. Description of the Related Art Double-sided pressure-sensitive adhesive tapes are frequently used for bonding molding materials and members such as home appliances and OA products due to their easy handling and good adhesive properties. Recycling opportunities are increasing for the purpose of reducing waste. At this time, it is necessary to peel off and remove the adhered double-sided pressure-sensitive adhesive tape from the adherend such as a molding material or a member.

[0003]

The conventional general double-sided pressure-sensitive adhesive tape used for bonding a molding material and a member has a large increase in bonding strength with time after lamination, and the pressure-sensitive adhesive adheres to an adherend when peeled. It often remains, and it takes a lot of time to remove it. In addition, the support used for the conventional double-sided pressure-sensitive adhesive tape includes non-woven fabric, foam,
Although a plastic film such as a polyester film is used, a non-woven fabric made of rayon or pulp, or when a foam is used for the support, the strength of the support is weak,
At the time of peeling, the tape breaks, making the peeling operation difficult. When a plastic film such as a polyester film is used as a support, the tape is not broken at the time of peeling because of its high strength, but it balances the adhesion of the adhesive to the surface of the plastic film and the adhesion to the adherend. It is difficult, and the adhesive may peel off from the interface of the plastic film used as the support by the adherend and remain on the adherend, and may be bonded to a member such as a plastic film nameplate or foam and punched. Occasionally, the pressure-sensitive adhesive also extends together with the support and adheres to the punching blade, or adheres to the members and adheres to each other.

The double-sided pressure-sensitive adhesive tape for recycling described in Japanese Patent Application Laid-Open No. 7-70527 is mainly composed of manila hemp and has a tensile strength of 1 kg each in the vertical and horizontal directions.
A proposal has been made in which pressure-sensitive adhesive layers are provided on both surfaces of a nonwoven fabric support having an f / 15 mm or more, and at least one of the pressure-sensitive adhesive layers is a water-soluble pressure-sensitive adhesive layer. However, this double-sided pressure-sensitive adhesive tape requires an operation of bringing a water-soluble pressure-sensitive adhesive layer into contact with water when peeling from an adherend such as a molding material, and is troublesome.

Further, the double-sided pressure-sensitive adhesive tape described in Japanese Patent Application Laid-Open No. 9-272850 is a non-woven fabric made of only manila hemp having a support having a high grain ratio and high strength properties,
In addition, an acrylic pressure-sensitive adhesive having a high elastic modulus of storage elastic modulus (G ′) at 50 ° C. of 4.5 × 10 ^{5 to} 6.0 × 10 ⁵ dyne / cm ² is used as the pressure-sensitive adhesive. .

This double-sided pressure-sensitive adhesive tape uses a non-woven fabric consisting of only manila hemp as a support, so that the tape does not break when peeled off. This is disadvantageous in that it is easy to perform, and a portion that is difficult to be impregnated with the adhesive is easily generated. Moreover, the range of the storage elastic modulus of the pressure-sensitive adhesive is determined to avoid the phenomenon that the pressure-sensitive adhesive remains due to cohesive failure. Since care has not been taken, there is the disadvantage that the material is easily broken between the support layers at the time of peeling, and the recyclability is not perfect due to its removal. Further, since the pressure-sensitive adhesive has a high modulus of elasticity, there is a defect that the adhesiveness is extremely reduced when the surface of the molding material or member has a rough surface such as a matte surface or has slight irregularities.

The present invention solves the above-mentioned problems, and is used for bonding a member such as plastic or foam to a molding material such as metal or plastic, and using a double-sided adhesive tape for the purpose of recycling the molding material or member. It is an object of the present invention to provide a double-sided pressure-sensitive adhesive tape that does not leave an adhesive on an adherend when being peeled off from the substrate, does not break between the support layers, and does not break the tape.

[0008]

The inventor of the present invention has proposed that a thickness of 30
The support is a non-woven fabric obtained by mixing 10% to 50% of either rayon or pulp with Manila hemp fiber and having a thickness of 50 μm on both sides of the support.
Not less than 90 μm and the weight average molecular weight is not less than 600,000 and not more than 10
The inventors have found that the above-mentioned problems can be solved by a double-sided pressure-sensitive adhesive tape provided with a re-peelable pressure-sensitive adhesive layer containing not more than 100,000 acrylic acid ester copolymer as a main component, and have accomplished the present invention.

The nonwoven fabric used in the present invention has a thickness of 30
It is made by mixing 10 to 50% of pulp or rayon with manila hemp fiber having a size of not less than μm and not more than 80 μm. By mixing pulp and rayon, Manila hemp fibers are less likely to agglomerate densely, and since there is no binding fiber part with high fiber density, a uniform nonwoven fabric with good adhesive impregnation and strong strength can be obtained. .

If the rayon or pulp is less than 10%,
Bound fiber parts having a high fiber density are generated, impregnating property of the pressure-sensitive adhesive is impaired, breakage occurs between the support layers at the time of peeling, and recyclability is impaired. 50 rayon or pulp
%, The expression of strength due to the entanglement of the fibers is weak, and the tape breaks at the time of peeling, and the recyclability is impaired.

When the thickness of the non-woven fabric is less than 30 μm, the strength of the support is low, and the tape breaks at the time of peeling, and the recyclability is impaired. When the thickness is larger than 80 μm, it is difficult to impregnate the entire nonwoven fabric layer with the adhesive, and there is a portion where the adhesive is not impregnated. Part of the double-sided adhesive tape remains.

The nonwoven fabric used in the present invention may be impregnated with a resin such as viscose, PVA or polyacrylamide as a paper strength enhancer.

The nonwoven fabric used in the present invention is obtained by a known production method and is not particularly limited. More specifically,
It is preferably obtained by a wet method, a round paper machine, a short paper machine,
Various known papermaking methods using a fourdrinier machine or the like are used. More preferably, in a round paper machine, the fibers are easily oriented in the longitudinal direction, and the strength of the nonwoven fabric in the transverse direction is weakened. Therefore, a short netting machine and a fourdrinier paper machine in which the fibers are hardly oriented in the longitudinal direction are used. .

The main component of the pressure-sensitive adhesive used in the present invention is a known acrylic ester copolymer. The acrylate copolymer is composed of (meth) acrylate and an unsaturated monomer copolymerizable therewith.

Examples of (meth) acrylic esters include n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, Isopentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, Examples include isononyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, and tridecyl (meth) acrylate.

Examples of unsaturated monomers copolymerizable with (meth) acrylic acid esters include alkyl (meth) acrylates other than those exemplified above as alkyl (meth) acrylates; hydroxyl, amino, and amide groups. (Meth) acrylates having an ether group or the like;
Aliphatic unsaturated (di) such as (meth) acrylic acid and fumaric acid
Carboxylic acids; aliphatic unsaturated hydrocarbons such as ethylene and butadiene; halogen-substituted aliphatic unsaturated hydrocarbons such as vinyl chloride; aromatic unsaturated hydrocarbons such as styrene and α-methylstyrene; vinyl acetate And vinyl ethers; unsaturated cyanide compounds such as acrylonitrile.

The pressure-sensitive adhesive of the present invention comprises an acrylic ester copolymer as a main component and is crosslinked by a crosslinking agent. Known crosslinking agents such as isocyanate compounds, epoxy resins and metal chelates can be used. Various additives such as a tackifier resin may be appropriately added to the pressure-sensitive adhesive.

The acrylic ester copolymer used in the present invention has a weight average molecular weight of 600,000 or more and 1,000,000 or less. If the weight average molecular weight is less than 600,000, if the double-sided pressure-sensitive adhesive tape is adhered to an adherend such as a molding material and peeled off after a lapse of time, the pressure-sensitive adhesive remains on the adherend and the recyclability is impaired. When the weight average molecular weight is more than 1,000,000, the impregnating property to the support nonwoven fabric is significantly impaired, the interlayer is easily broken at the time of peeling, and the adhesive property is impaired.

The thickness of the pressure-sensitive adhesive provided on both sides of the support nonwoven fabric in the present invention is 50 to 90 μm, respectively. If the thickness of the pressure-sensitive adhesive is less than 50 μm, it is advantageous for re-peelability, but sufficient adhesive properties and reliability required for a double-sided tape cannot be obtained. The adhesive is 90 μm
If the thickness is larger, the adhesive tends to be cohesive and destructive at the time of peeling, and the adhesive remains on the adherend and the recyclability is impaired.

The method for producing the double-sided pressure-sensitive adhesive tape of the present invention is not particularly limited, and can be obtained by a known method. As an example, apply an adhesive to release paper and dry it,
There are a transfer method in which the adhesive is applied to a nonwoven fabric support, and a direct method in which an adhesive is directly applied to the nonwoven fabric support and dried. Nameplate,
The double-sided tape used for OA equipment and the like is preferably manufactured by a transfer method in order to emphasize smoothness of a coated surface.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION A non-woven fabric having a thickness of 30 μm or more and 80 μm or less, which is prepared by mixing Manila hemp fiber with 10% to 50% of rayon or pulp is used as a support. 50 μm or more 90
μm or less, the weight-average molecular weight is 600,000 or more and 1,000,000 or less by providing a re-peelable pressure-sensitive adhesive layer containing as a main component a plastic, a member such as a foam, a metal, a plastic, etc. Used to bond molding materials, when the double-sided adhesive tape is peeled off from the adherend for the purpose of recycling the adherend such as molding materials and members, the adhesive remains on the adherend or breaks between the support layers A double-sided pressure-sensitive adhesive tape can be obtained without causing the tape to break.

[0022]

Next, the present invention will be described with reference to examples.

(Example 1) Manila hemp 70% and pulp 30
% Of an acrylic ester copolymer having a weight-average molecular weight of 650,000 and having butyl acrylate as a main component on both sides of the support.
To 5 parts by weight, 5 parts of a rosin ester having a softening point of 115 ° C. as a tackifying resin was added, and pressure-sensitive adhesives cross-linked by an isocyanate-based cross-linking agent were respectively provided with a thickness of 50 μm by a transfer method to obtain a double-sided pressure-sensitive adhesive tape.

(Example 2) A nonwoven fabric similar to that of Example 1 was used as a support, and 95 parts by weight of an acrylic acid ester copolymer having butyl acrylate as a main component and a weight average molecular weight of 750,000 was used as a softening point as a tackifying resin. A double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 by using 5 parts of a rosin ester at 115 ° C. and using a pressure-sensitive adhesive cross-linked with an isocyanate-based cross-linking agent.

(Example 3) 75% of manila hemp and rayon 2
A double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 2 using a non-woven fabric of which 5% was formed to a thickness of 50 μm by a wet method as a support.

Comparative Example 1 95% by weight of an acrylic ester copolymer having a weight average molecular weight of 750,000 and a butyl acrylate as a main component was used as a support, using a nonwoven fabric made of 100% Manila hemp to a thickness of 40 μm by a wet method. As a tackifying resin, 5 parts of a rosin ester having a softening point of 115 ° C. was added, and a double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 using a pressure-sensitive adhesive crosslinked with an isocyanate-based crosslinker.

Comparative Example 2 Manila hemp 30% and pulp 70
Rosin having a softening point of 110 ° C. as a tackifying resin was added to 90 parts by weight of an acrylate copolymer having a weight average molecular weight of 450,000 and containing butyl acrylate as a main component. 1 ester
A double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1, except that 0 part was added and the pressure-sensitive adhesive crosslinked with an isocyanate-based crosslinker was used.

(Comparative Example 3) The same nonwoven fabric as in Example 1 was used as a support, and 95 parts by weight of an acrylic acid ester copolymer having a weight-average molecular weight of 1.1 million and containing butyl acrylate as a main component was mixed with a softening point as a tackifying resin. A double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1, using 5 parts of a rosin ester at 100 ° C. and cross-linking with an isocyanate-based cross-linking agent.

(Releasability) Evaluation was made based on the presence or absence of adhesive remaining on the adherend at the time of peeling the double-sided tape, cutting of the tape, and occurrence of interlayer destruction of the support. A test piece was prepared by laminating a 5-mm-thick urethane foam as a member to one side of the double-sided pressure-sensitive adhesive tape, making it 25 mm wide, and polishing it on a SUS-304 plate polished with # 280 sandpaper as a molding material. Back and forth, pasted and made. After leaving this test piece at room temperature for one day, it was put into a sunshine weather meter for 400 hours. After the test piece was taken out, it was left at room temperature for one day, and the tensile speed was 300 in accordance with JIS-Z-0237.
A peel test was performed at mm / min. At this time, the presence of adhesive remaining on the adherend, the cutting of the tape, and the presence or absence of interlayer destruction of the support were each visually checked. If each phenomenon was observed, it was evaluated as x. Was evaluated.

Using the double-sided pressure-sensitive adhesive tapes of Examples 1 to 3 and Comparative Examples 1 to 3, the above-mentioned releasability test was carried out. The results are shown in Table 1.

[0031]

[0032]

When the double-sided pressure-sensitive adhesive tape of the present invention is used for bonding a member such as plastic or foam to a molding material such as metal or plastic, the double-sided pressure-sensitive adhesive tape is applied for recycling of the molding material or member. When peeled from the substrate, the adhesive does not remain on the adherend, the tape is not cut, and the tape is not broken between the support layers, so that good peelability can be obtained.

Continued on the front page F-term (reference) 4J004 AA10 AB01 CA02 CB01 CC02 EA05 FA05 FA08 4J040 CA061 DA031 DB061 DB081 DC031 DD051 DE021 DF011 DF041 DF051 DF061 DF081 DG001 GA03 GA05 GA07 GA08 GA13 GA01 MA09 AF10 LA10 AJ03 EA04 EA08 EA30 FA30 GA42

Claims (1)

[Claims] 1. A manila hemp fiber having a thickness of 30 μm or more and 80 μm or less, which is made by adding either rayon or pulp to 10%
A non-woven fabric mixed with 50% is used as a support, and on both sides of the support, a release mold mainly composed of an acrylate copolymer having a thickness of 50 μm or more and 90 μm or less and a weight average molecular weight of 600,000 or more and 1,000,000 or less. A double-sided pressure-sensitive adhesive tape provided with a pressure-sensitive adhesive layer.