JP2000313862A - Pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] For rubber and thermoplastic elastomer molded products,
Sufficient adhesive strength can be obtained without applying conventional treatments such as primer application, and long-time vulcanization at high temperature is not necessary, so production efficiency is high and safety is high. Provided are a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with little deterioration. SOLUTION: The first constitution of the present invention comprises 100 parts by weight of an SIS block copolymer and a tackifying resin 60 to 200.
In the pressure-sensitive adhesive containing an essential component by weight, the S
The amount of diblock in the IS block copolymer is 30 to 80.
% By weight, wherein the tackifier resin contains a C5 petroleum resin, and the tackifier resin other than the C5 petroleum resin has a hydroxyl value of 25 or less. A second configuration is a pressure-sensitive adhesive sheet characterized in that the pressure-sensitive adhesive described above is provided on at least one surface of a support.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to rubbers such as natural rubber, chloroprene rubber, EPT (ethylene-propylene-terpolymer) rubber, olefins, styrenes and the like.
The present invention relates to a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet used for bonding a molded article made of a thermoplastic elastomer such as a PVC or a urethane.

[0002]

2. Description of the Related Art Molded articles of rubber or thermoplastic elastomer (hereinafter referred to as molded articles of rubber, etc.) are used for automobile parts, home appliances, OA, and the like.
It is widely used in various industrial products in addition to components for equipment.
However, molded products such as rubber are generally blended with various fillers, vulcanizing agents, oils, plasticizers, and the like, or when vulcanizing molded products, they are easily separated from the press mold. Since the release agent such as silicone oil adheres to the surface of the molded article, the adhesive strength to the molded article is low. Also, when sticking molded products such as rubber to curved surfaces with tapes, etc.
Since the molded article has high elasticity, there is a problem that the molded article is easily peeled off due to poor adhesiveness.

[0003] Therefore, a method has been hitherto used in which a surface of a molded article such as rubber as an adherend is treated in the order of buffing, solvent washing, and primer coating, and an adhesive sheet is attached to the adherend. Had been taken. However, the working environment is poor due to the use of primers and solvents, and the working process is complicated,
There is a problem that the adhesiveness varies due to variations in buffing.

In order to solve these problems, Japanese Patent Laid-Open Publication No.
In JP-A-78634, a high molecular weight rubbery polymer such as polyisobutylene is added with a liquid or semi-liquid rubber having a medium molecular weight and a tackifier and / or a softener having a low molecular weight and a gel fraction of 10 to 10. It is disclosed that the pressure-sensitive adhesive and the pressure-sensitive adhesive sheet set to 40% exhibit a sufficient adhesive force without subjecting EPT rubber or the like to buffing or the like. However, this pressure-sensitive adhesive sheet requires a vulcanization and maturation at high temperature for a long time after applying a pressure-sensitive adhesive to the substrate during the twisting process and the pressure-sensitive adhesive. The use of a peroxide compound or a thiuram compound causes many problems in handling and safety.

[0005] Conventionally, pressure-sensitive adhesives mainly composed of SIS block copolymers have been used for various purposes. However, for various industrial uses such as automobiles, home appliances, and OA equipment in which molded articles such as rubber are used, storage stability under high temperature and high humidity and durability during use are required.
The pressure-sensitive adhesive mainly composed of the IS block copolymer has a problem that when used under high temperature and high humidity, the deterioration is apt to occur and the stability and durability are poor.

Further, molded articles such as rubbers generally contain various fillers, vulcanizing agents, oils, plasticizers, etc., and the gloss of the surface due to the bleed component over time (particularly under high temperature and high humidity). There is a problem that a sticky feeling is generated.

[0007]

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to omit a buffing step for a molded article such as a rubber to be adhered, and to perform a sneaking step for an adhesive, a high-temperature vulcanization. Even if it does not require a process and does not contain peroxides that have safety problems, it can demonstrate sufficient cohesive strength and adhesive strength,
An object of the present invention is to provide a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet which are less deteriorated even under high temperature and high humidity and which improve the surface gloss over time of a molded article such as rubber.

[0008]

Means for Solving the Problems As a result of diligent studies, the present inventors have found that an adhesive comprising a SIS block copolymer having a specific diblock amount and a specific tackifying resin is not suitable for safety, such as a peroxide. It does not require a twisting process or long-time vulcanization at high temperatures, and can exhibit sufficient adhesive strength without buffing or other treatment on the adherend.
It has been found that deterioration under high temperature and high humidity can be suppressed, and the present invention has been completed.

That is, the first constitution of the present invention comprises 100 parts by weight of an SIS block copolymer and 60 to 2 tackifier resins.
In an adhesive containing 00 parts by weight as an essential component,
The amount of diblock in the SIS block copolymer is 30 to
80% by weight, wherein the tackifier resin contains a C5 petroleum resin, and the hydroxyl value of the tackifier resin other than the C5 petroleum resin is 25 or less.

[0010] The composition of the present invention is a pressure-sensitive adhesive composition characterized in that 10 to 30% by weight of the above-mentioned tackifying resin amount is a liquid-state tackifying resin and / or a softener at room temperature.

[0011] The composition of the present invention is the pressure-sensitive adhesive composition, wherein the tackifier resin having a hydroxyl value of 25 or less is a rosin resin.

Further, a second structure of the present invention is a pressure-sensitive adhesive sheet characterized in that the above-mentioned pressure-sensitive adhesive is provided on at least one surface of a support.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The SIS block copolymer used in the present invention is not particularly limited except that the diblock amount is 30 to 80% by weight. If the diblock amount is less than 30% by weight, sufficient adhesive strength to a molded article such as rubber cannot be obtained. If it exceeds 80% by weight, the cohesive strength of the pressure-sensitive adhesive is significantly reduced. The molecular weight of the SIS block copolymer is preferably in the range of 10,000 to 800,000, and more preferably in the range of 30,000 to 500,000. If it is less than 10,000, the cohesive force of the pressure-sensitive adhesive is significantly reduced. On the other hand, 80
If it exceeds 10,000, wetting of molded articles such as rubber is reduced, and sufficient adhesive strength cannot be obtained.

The C5 petroleum resin used in the present invention is a resin obtained by polymerizing a residue obtained by extracting and separating isoprene and cyclopentadiene from a C5 fraction obtained by cracking naphtha. Examples of the resin include Escolets 1202 and 1304.
1401 (manufactured by Tonex), Wing Tack 95 (manufactured by Goodyear), Quinton K100, R100, F1
00 (manufactured by Nippon Zeon), Pico Tack 95, Pico Pale 1
00 (manufactured by Rika Hercules) and the like.

The tackifying resin other than the C5 petroleum resin used in the present invention includes terpene resins, rosin resins,
Terpene-phenol resin, styrene resin, cumarone-indene resin, xylene resin, phenol resin, C5
Other petroleum resins (aromatic, alicyclic, etc.). Preferably, a rosin-based resin is used. When the hydroxyl value of these tackifier resins exceeds 25, the SIS block copolymer is easily degraded under high temperature and high humidity, and causes the main chain of the SIS block copolymer to be cut.

The total amount of the tackifying resin used in the present invention is 6
If the amount is less than 0 parts by weight, the adhesive strength to a molded article such as rubber decreases, and the adhesiveness after moisture resistance deterioration also decreases. 200 total
If the amount exceeds the weight part, the heat-resistant holding power is reduced.

Examples of the liquid tackifying resin and / or softening agent used in the present invention include the above-mentioned tackifying resin liquid at room temperature, and low-molecular-weight liquid rubber such as process oil, polyester plasticizer, and polybutene. Can be The ratio of the liquid tackifying resin and / or the softener to the total amount of the tackifying resin is preferably 10 to 30% by weight. 10% by weight
If it is less than 30%, the wettability to a molded article such as rubber deteriorates, and the adhesive strength decreases. If it exceeds 30% by weight, the cohesive force deteriorates, and some resilience resistance causes floating.

In the present invention, other polymer components,
Crosslinking agents can be used. In addition, various additives generally used in pressure-sensitive adhesives, for example, antioxidants, ultraviolet absorbers, fillers, pigments, thickeners, and the like can be used as long as the adhesive strength is not reduced. The synthetic rubber-based pressure-sensitive adhesive of the present invention thus adjusted is usually diluted with an organic solvent such as toluene or hexane, and is dissolved in a solution or at a high temperature, and is used for bonding molded articles such as rubber. Used as

The pressure-sensitive adhesive may be applied directly to the adherend. Generally, the adhesive is provided on at least one side of the support and used in the form of a tape or a sheet. It is desirable to form a double-sided tape with a pressure-sensitive adhesive provided on both sides of the support for the purpose of bonding to the support. Usually, the above-mentioned pressure-sensitive adhesive is once provided on a release paper (in the case of a solution, dried after coating) and bonded to both sides of a support. The support is not particularly limited, and examples thereof include a porous support such as a nonwoven fabric, a cloth, and paper, and a plastic film such as a polyester film, a polyethylene film, a polypropylene film, and a polyvinyl chloride film. The thickness is usually 5
Those having a size of about 200 μm are used. In order to improve the adhesion to the support, a corona treatment or a primer treatment may be performed.

The thickness of the adhesive provided on the support is usually 1
The thickness is preferably about 0 to 400 μm, but is not limited thereto. Also, providing the adhesive on one side of the support,
On the other hand, a differential type double-sided tape specification in which a different adhesive such as an acrylic adhesive is provided may be used.

[0021]

EXAMPLES Examples of the present invention will be specifically described below, but are not limited thereto.

(Examples 1 to 4) An SIS block copolymer, a tackifier resin, a liquid tackifier resin / softener and an antioxidant were blended in the weight ratios shown in Table 1, and dissolved in toluene to prepare a pressure-sensitive adhesive solution. did. This solution was applied on a separator using an applicator so that the thickness after drying was 60 μm, and dried at 80 ° C. for 3 minutes. Next, two layers of the pressure-sensitive adhesive formed on the separator were prepared, and these were laminated on both sides of a 50 μm-thick nonwoven fabric, and then laminated at 90 ° C. under a pressure of 4 kgf / cm 2. , To prepare a double-sided pressure-sensitive adhesive sheet.

(Comparative Examples 1 to 6) An SIS block copolymer, a tackifying resin, a liquid tackifying resin / softening agent and an antioxidant were blended in the weight ratios shown in Table 2, and the pressure-sensitive adhesive solution and the A double-sided pressure-sensitive adhesive sheet was produced.

The double-sided adhesive sheets obtained in Examples 1 to 4 and Comparative Examples 1 to 6 were evaluated for adhesive strength, resistance to moist heat deterioration, resilience, surface gloss and heat retention. Hereinafter, the evaluation results are shown in Tables 1 and 2. The evaluation was performed in the following manner.

<Adhesive force>: A double-sided pressure-sensitive adhesive sheet was adhered to EPT (ethylene-propylene-terpolymer) rubber and chloroprene rubber under a pressure of 2 kg × 1 reciprocation, and after 30 minutes, at a pulling speed of 300 mm / min.゜ Peel adhesion was measured.

<Moisture / heat deterioration resistance>: A double-sided pressure-sensitive adhesive sheet was attached to EPT rubber at a pressure of 2 kg × 1 reciprocation, and the temperature was 85 ° C.
Evaluation was made of a decrease in adhesive strength after being left for 7 days in an environment of 85% RH. ：: No decrease in adhesive strength after deterioration due to moist heat ○: No significant decrease in adhesive strength (80% or more of initial) ×: Cohesive failure occurs and significant decrease in adhesive strength (50% or less of initial)

<Rebound resistance>: EPT rubber having a width of 20 mm was attached to an aluminum plate bent at 90 ° with a double-sided adhesive sheet so that the edge portion became 10 mm in length.
The peeling state after standing for 7 days in an environment of 85% RH was evaluated. ◎: no peeling ○: floating ×: whole peeling

<Surface gloss>: A thermoplastic elastomer was adhered to a steel sheet specified in JIS-Z0237 by a double-sided pressure-sensitive adhesive sheet, and the surface of the thermoplastic elastomer after standing for 7 days in an environment of 85 ° C. and 85% RH was used. The gloss was evaluated. ○: no gloss ×: glossy

<Heat resistance>: A double-sided pressure-sensitive adhesive sheet was adhered to a steel sheet specified in JIS-Z0237 with a sticking area of 20 mm width × 20 mm, and the falling time when a load of 500 g was applied at 70 ° C. was measured. It was measured. ○: 1 hour or more ×: less than 1 hour

In the above evaluation, the EPT of the adherend was
Rubber and chloroprene rubber having a thickness of 1 mm and a hardness of 60 ° (made by Kuraray) were used. The thermoplastic elastomer used was an olefin-based thermoplastic elastomer having a thickness of 1 mm. The formulations and evaluation results are shown in Tables 1 and 2 below.

[0031]

[Table 1]

[0032]

[Table 2]

Tables (1) to (10) in Tables 1 and 2 are as follows. Further, () of the tackifier resin represents a hydroxyl value. Weight average molecular weight 200,000, styrene content 14% by weight. Weight average molecular weight 170,000, styrene content 16% by weight Weight average molecular weight 170,000, styrene content 15% by weight C5 petroleum resin: number average molecular weight 885, softening point 100 ° C rosin-modified phenol: number average molecular weight 670, softening point 150 ° C Leveled rosin ester: number average molecular weight 1,000, softening point 125 ° C Polymerized rosin ester: number average molecular weight 880, softening point 125 ° C Hydrogenated terpene phenol: number average molecular weight 820, softening point 130 ° C Low molecular weight polybutene (liquid): HV-100 manufactured by Nippon Oil Co., Ltd. (10) Hindered phenol: Irganox 1010 manufactured by Ciba Specialty Chemicals

[0034]

As described above, the pressure-sensitive adhesive of the present invention comprising a SIS block copolymer having a specific diblock amount and a specific tackifying resin does not contain peroxides and the like, which are problematic in safety, It is a pressure-sensitive adhesive that does not require a vulcanizing process at high temperatures or for a long time at high temperatures.It can exhibit sufficient adhesive strength to molded products such as rubber without the need for conventional buffing or primer treatment. Deterioration under high humidity can be suppressed.
Further, the surface gloss over time of a molded article such as rubber can be improved.

Continued on the front page F term (reference) 4J004 AA05 AB01 CA02 CA04 CA05 CA06 CB01 CB02 CC02 EA05 FA05 4J040 BA202 DM011 DN032 JA09 JB09 KA26 KA31 MA10 MA11 MA12

Claims (4)

[Claims] In a pressure-sensitive adhesive containing 100 parts by weight of an SIS block copolymer and 60 to 200 parts by weight of a tackifier resin as essential components, the amount of diblock in the SIS block copolymer is 30 to 80% by weight. A pressure-sensitive adhesive composition, wherein the tackifier resin contains a C5 petroleum resin, and the hydroxyl value of the tackifier resin other than the C5 petroleum resin is 25 or less. 2. The pressure-sensitive adhesive composition according to claim 1, wherein 10 to 30% by weight of the tackifying resin is a liquid-state tackifying resin and / or a softener at room temperature. 3. The pressure-sensitive adhesive composition according to claim 1, wherein the tackifier resin having a hydroxyl value of 25 or less is a rosin resin. 4. The method according to claim 1, wherein at least one surface of the support is provided.
A pressure-sensitive adhesive sheet provided with the pressure-sensitive adhesive according to any one of the above.