JPH0578634A - Rubber based pressure-sensitive adhesive and adhesive sheets therefrom - Google Patents

Abstract

PURPOSE:To obtain the subject adhesive consisting of specific ratio of each specific polyisobutylene, etc., rubber and tackiness-providing agent, etc., having prescribed gel fraction and having excellent adhesion strength without carrying out buffing or primer coating, and suitable as automotive members, etc. CONSTITUTION:The objective adhesive consisting essentially of (A) 100 pts.wt. polyisobutylene, butyl rubber or halogenated butyl rubber having 200000-1500000 weight-average molecular weight, (B) 30-300 pts.wt. liquid is semi-liquid rubber having < 10000-50000 weight-average molecular weight and (C) 30-300 pts.wt. tackiness-providing agent or/and softening agent having < 100000 weight-average molecular weight, and being 10-40% in gel fraction. Furthermore, layers of the adhesive are provided on both faces of a substrate to provide the adhesive sheets.

Description

Detailed Description of the Invention

[0001]

The present invention relates to natural rubber, chloroprene rubber, EPT (ethylene-propylene terpolymer).
The present invention relates to a rubber-based pressure-sensitive adhesive used for adhering a vulcanized rubber molded product made of rubber or the like and its adhesive sheets.

[0002]

2. Description of the Related Art Vulcanized rubber moldings of this type are widely used as automobile parts, home electric appliances, OA equipment parts, and various industrial products.

However, these rubber molded products contain a large number of various adhesion-inhibiting substances such as various fillers, vulcanizing agents, oil components, etc. as a compounded product, and in the process of vulcanizing the rubber molded product, they are molded from a press mold. Since a mold release agent such as silicone oil is used to improve the mold release, the adhesiveness of the surface of the molded product is poor.

Moreover, since these vulcanized rubber molded products have high elasticity, when they are attached to a curved surface, they are bonded and fixed in a state in which stress is applied by the elastic action. However, due to this and the poor adhesiveness of the surface of the molded product, there is a problem that the molded product is easily peeled off after being bonded and fixed.

For this reason, conventionally, the adhered surface of a vulcanized rubber molded product is first buffed, then solvent washed and primer-coated.
It has been a common practice to apply a coating, attach pressure-sensitive adhesive sheets to this, and fix it to another adherend.

[0006]

However, the above-mentioned treatments such as buffing and primer coating require a lot of man-hours, and buffing powder and solvent may scatter to deteriorate the working environment. In the process, there is a problem that the degree of buffing tends to vary, and the adhesive strength also varies accordingly.

In view of the above circumstances, the present invention is a rubber system capable of obtaining a sufficient adhesive strength without subjecting a vulcanized rubber molded product to conventional treatments such as buffing and primer coating. It is intended to provide a pressure sensitive adhesive and its adhesive sheet.

[0008]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that as an essential component of an adhesive, a polymer component having a specific molecular weight such as a rubbery polymer or By using a combination of three types of tackifiers and setting the gel fraction of the entire adhesive containing these components within a specific range, a vulcanized rubber molded product can be obtained.
Knowing that it can be fully adhered without the need for conventional buffing or primer coating,
The present invention has been completed.

That is, the present invention comprises the following three components a to c: a) 100 parts by weight of polyisobutylene, butyl rubber or halogenated butyl rubber having a weight average molecular weight of 200,000 to 1.5 million b) a weight average molecular weight of 10,000 to 15 30 to 300 parts by weight of liquid or semi-liquid rubber c) Contains 30 to 300 parts by weight of a tackifier or / and a softening agent having a weight average molecular weight of less than 10,000 as an essential component and a gel fraction of 10 to 10
The present invention relates to a rubber-based pressure-sensitive adhesive characterized by being in a range of 40%. The present invention also relates to an adhesive sheet in which a layer of the rubber-based pressure-sensitive adhesive is provided on one surface or both surfaces of a base material to form a sheet shape or a tape shape. ..

[0010]

The rubber polymer of the component a in the present invention has a high affinity for a vulcanized rubber molded product and is a polymer which exhibits a selective wettability by eliminating the adhesion-inhibiting substance in the surface layer. As-, any one of polyisobutylene which is a homopolymer of isobutylene, butyl rubber which is a copolymer of isobutylene and 1 to 3% by weight of isoprene, and halogenated butyl rubber obtained by brominated or chlorinated this butyl rubber is used. ..

The molecular weight of this rubbery polymer is required to be in the range of 200,000 to 1,500,000 in terms of weight average molecular weight,
Particularly preferably, it is in the range of 300,000 to 1,000,000.
When it is less than 200,000, the cohesive force of the adhesive cannot be sufficiently obtained, and when the vulcanized rubber molded product is attached to a curved surface, the adhesive is likely to be peeled off after being bonded and fixed. On the other hand, when it is more than 1.5 million, the cohesive force of the adhesive becomes too high, and it is difficult to obtain sufficient wetting with the vulcanized rubber molded product.

Examples of the liquid or semi-liquid rubber of the component b in the present invention include polyisobutylene, polybutene, ethylene propylene rubber and the like. Among these, polyisobutylene is most preferably used. The component b is well compatible with the rubbery polymer of the component a and appropriately plasticizes the polymer to improve the wettability of the vulcanized rubber molded article.

The above-mentioned liquid or semi-liquid means a state at room temperature (25 ° C.), and semi-liquid means a state in which a fluid phenomenon is exhibited although it is very loose. Means

The molecular weight of such liquid or semi-liquid rubber is required to be in the range of 10,000 to 150,000 in terms of weight average molecular weight, and particularly preferably in the range of 20,000 to 120,000. .. If it is less than 10,000, the cohesive force of the adhesive cannot be sufficiently obtained, and in the case where a vulcanized rubber molded product is attached to a curved surface, the adhesive tends to be peeled off after adhesion and fixation. On the other hand, if it is more than 150,000, a sufficient plasticizing effect cannot be obtained, and the cohesive force of the adhesive becomes too high, so that it is difficult to obtain sufficient wetting with the vulcanized rubber molded product.

The amount of the liquid or semi-liquid rubber of component b used is 100 parts by weight of the rubbery polymer of component a.
The amount is required to be in the range of 30 to 300 parts by weight, particularly preferably 50 to 150 parts by weight. Thirty
If the amount is less than the weight part, a sufficient plasticizing effect cannot be obtained, and the cohesive force of the adhesive becomes too high, and it is difficult to obtain sufficient wetting with the vulcanized rubber molded product. On the other hand, if the amount is more than 300 parts by weight, the cohesive force of the adhesive cannot be sufficiently obtained, and in the case where a vulcanized rubber molded product is attached to a curved surface, the adhesive is likely to be peeled off after the adhesive fixing.

As the tackifier which is one of the component c in the present invention, a terpene resin, terpene-pheno-
In addition to solid tackifiers that are solid at room temperature, such as resin, petroleum resin, styrene resin, coumarone-indene resin, xylene resin, and phenol resin, various liquid tackifiers at room temperature can be used. .. Further, as the softening agent which is another one of the component c, a low molecular weight liquid rubber such as a process oil, a polyester type plasticizer and polybutene can be mentioned.

The molecular weight of these c components is required to be less than 10,000 in terms of weight average molecular weight, and particularly preferably 200 to
It should be 5,000. If it is 10,000 or more, the cohesive force of the adhesive becomes too high, and it is difficult to obtain sufficient wetting with the vulcanized rubber molded product.

The amount of the tackifier or / and the softening agent used as the component c is such that the rubber polymer of the component a is used.
It is necessary to set the range of 30 to 300 parts by weight per 100 parts by weight, and it is particularly preferable to set the range of 40 to 150 parts by weight. If the amount is less than 30 parts by weight, the cohesive force of the adhesive becomes too high, and it is difficult to obtain sufficient wetting with the vulcanized rubber molded product. On the other hand, if the amount is more than 300 parts by weight, the cohesive force of the adhesive cannot be sufficiently obtained, and in the case where a vulcanized rubber molded product is attached to a curved surface, the adhesive is likely to be peeled off after the adhesive fixing.

In the present invention, in addition to the above three components a to c, other polymer components and crosslinking agents can be used, and various compounding agents used for general pressure sensitive adhesives, for example, Antioxidants, ultraviolet absorbers, fillers, pigments, extenders and the like can also be used. However, the amount of these optional components used is required to be 100 parts by weight or less, and particularly preferably 80 parts by weight or less, per 100 parts by weight of the rubber polymer of the component a. If the amount exceeds 100 parts by weight, there is an adverse effect such that the characteristics of the rubber-based pressure-sensitive adhesive are impaired.

The rubber-based pressure-sensitive adhesive in the present invention contains the above-mentioned three components a to c as essential components, contains the above-mentioned various optional components as required, and has a gel fraction of 1
The major feature is that it is in the range of 0 to 40%, particularly preferably in the range of 10 to 30%.

That is, in this type of rubber-based pressure-sensitive adhesive, if the gel fraction is less than 10%, sufficient cohesive force of the adhesive cannot be obtained, and the vulcanized rubber molded product is attached to a curved surface. In some cases, it easily peels off after adhesion and fixation. On the other hand, when it is more than 40%, the cohesive force of the adhesive becomes too high, and it is difficult to obtain sufficient wetting with the vulcanized rubber molded product.

To set the gel fraction as described above,
c A method of appropriately crosslinking a rubber-based pressure-sensitive adhesive containing three components is effective. Examples of this cross-linking method include a cross-linking method using a peroxide, a cross-linking method using a quinonedioxime and a peroxide, a cross-linking method using zinc oxide and various accelerators, and the like. Alternatively, a method of crosslinking with an electron beam may be used. The method of crosslinking with an electron beam is particularly effective when the rubber polymer of the component a is a halogenated butyl rubber.

The rubber-based pressure-sensitive adhesive of the present invention thus prepared is usually prepared as a solution using an appropriate organic solvent such as toluene, hexane, heptane, and the like. Used as an adhesive for various purposes.

In this use, the above-mentioned adhesive solution may be directly applied to an adherend composed of a vulcanized rubber molded product, but it is usually a sheet-like sheet formed in a layer on an appropriate substrate. It is good to use as an adhesive sheet such as film, tape or tape. Further, in this case, the layer may be formed on only one side of the base material, but for the purpose of adhering the vulcanized rubber molded article to another adherend, so-called double-sided adhesion in which a layer is formed on both sides of the base material It is desirable to use sheets.

When obtaining such double-sided adhesive sheets,
For example, the above adhesive solution may be applied on a separator once and dried to form a layer, two of these may be prepared, and these may be attached to both surfaces of the base material.

As the substrate, a porous substrate such as a non-woven fabric, a woven fabric or paper, or a plastic film such as a polyester film, a polyethylene film, a polypropylene film or a polyvinyl chloride film, usually having a thickness of 5
The thickness of about 200 μm is used. If you use a plastic film, when you leave it for a long time after adhesive use,
Since the migration of the adhesion-inhibiting component from the one surface side to the other surface side of the film can be prevented, the decrease in the adhesive strength with time is suppressed. If an undercoating treatment is applied to these base materials before forming the adhesive layer, the anchoring force of the adhesive is improved.

It is desirable that the thickness of the adhesive layer provided on the base material, that is, the layer of the rubber-based pressure-sensitive adhesive is usually about 10 to 400 μm on one side, but the thickness is not limited to this. However, it can be appropriately determined according to the purpose of use.

When a double-sided adhesive sheet is obtained, a layer of the above-mentioned rubber-based pressure-sensitive adhesive is provided only on one surface of the substrate,
Modifications may be made by providing the other side with a layer of another adhesive, in particular an acrylic pressure sensitive adhesive.

According to this aspect, a layer of a rubber-based pressure-sensitive adhesive can be used for adhesion to a vulcanized rubber molded article, and a layer of the acrylic pressure-sensitive adhesive or the like can be used for adhesion to other adherends. Therefore, more desirable adhesive properties can be obtained depending on the purpose of use. The acrylic pressure-sensitive adhesive layer may contain various additives such as coloring pigments, as in the case of the rubber pressure-sensitive adhesive layer.

[0030]

As described above, in the present invention, as the essential components of the adhesive, three types of polymer components such as rubbery polymers having a specific molecular weight and tackifiers are used in combination, and these components are used. By setting the gel fraction of the adhesive as a whole in a specific range, when bonding vulcanized rubber molded products, especially when bonding this molded product to an adherend with a curved surface Polishing and primer
It is possible to obtain a rubber-based pressure-sensitive adhesive that exhibits a sufficient adhesive strength and its adhesive sheet without applying treatment such as coating.

[0031]

EXAMPLES Next, examples of the present invention will be specifically described in comparison with comparative examples. In the following, "parts" means "parts by weight".

Example 1 Brominated butyl rubber (weight average molecular weight 500,000) 100 parts Polyisobutylene (weight average molecular weight 80,000) 120 parts Petroleum resin (weight average molecular weight 2,500) 100 parts Rosin-based liquid resin (weight average molecular weight) 630) 50 parts Zinc oxide 3 parts Zinc chloride 2 parts Zinc isobutylxanthate 4 parts N.N'-diphenyl-p-phenylenediamine 1 part

The above components were dissolved in 700 parts of toluene to prepare a rubber-based pressure-sensitive adhesive solution. This solution was applied onto a separator using an applicator so that the thickness after drying would be 70 μm, and dried at 100 ° C. for 3 minutes.

Next, two layers of the rubber-based pressure-sensitive adhesive formed on the above separator were prepared, and these were laminated on both sides of a non-woven fabric having a thickness of 50 μm, and then at 60 ° C.
It was left for 2 days to prepare a double-sided adhesive sheet.

Example 2 Butyl rubber (weight average molecular weight 500,000) 100 parts Polyisobutylene (weight average molecular weight 30,000) 70 parts Petroleum resin (weight average molecular weight 2,500) 100 parts Terpene liquid resin (weight average molecular weight 680) 50 parts p-benzoquinone dioxime 2 parts cumene hydroperoxide 0.5 parts cobalt naphthenate 0.05 parts

The above components were dissolved in 590 parts of toluene to prepare a rubber pressure-sensitive adhesive solution. Using this solution, a double-sided adhesive sheet was produced in the same manner as in Example 1 below.

Example 3 Brominated butyl rubber (weight average molecular weight 450,000) 50 parts Polyisobutylene (weight average molecular weight 1,000,000) 50 parts Polyisobutylene (weight average molecular weight 30,000) 70 parts Process oil (weight average molecular weight 200) 50 parts Zinc oxide 2 parts Zinc chloride 2 parts Zinc isopropylxanthate 4 parts N.N'-diphenyl-p-phenylenediamine 1 part

The above components were dissolved in 425 parts of toluene to prepare a rubber-based pressure-sensitive adhesive solution. Using this solution, a double-sided adhesive sheet was produced in the same manner as in Example 1 below.

Example 4 80 parts of n-butyl acrylate, 17 parts of 2-ethylhexyl acrylate, 3 parts of acrylic acid and ethyl acetate 233
Part of the monomer solution was radical-polymerized by a conventional method to obtain a polymer solution containing an acrylic polymer having a weight average molecular weight of 600,000. To this, 100 parts of the acrylic polymer and 3 parts of the trifunctional low molecular weight isocyanate compound were added and mixed to prepare a solution of the acrylic pressure-sensitive adhesive.

Next, the solution of the rubber-based pressure-sensitive adhesive of Example 1 was applied onto one surface of a polyester film having a thickness of 12 μm so that the thickness after drying was 70 μm, and 100
After drying at ℃ for 3 minutes, it was left at 60 ℃ for 2 days. Then, a solution of the acrylic pressure-sensitive adhesive is dried on the other surface of the polyester film to a thickness of 70.
It is applied so that it becomes μm, and dried at 100 ° C. for 3 minutes,
A double-sided adhesive sheet was prepared.

Comparative Example 1 Brominated butyl rubber (weight average molecular weight 500,000) 100 parts Polyisobutylene (weight average molecular weight 100,000) 80 parts Petroleum resin (weight average molecular weight 2,500) 70 parts Terpene liquid resin (weight average molecular weight) 300) 50 parts Zinc oxide 2 parts Tetramethylthiuram disulfide 4 parts

The above components were dissolved in 638 parts of toluene to prepare a rubber-based pressure-sensitive adhesive solution. A double-sided adhesive sheet was produced in the same manner as in Example 1 except that this solution was used.

Comparative Example 2 Brominated butyl rubber (weight average molecular weight 500,000) 100 parts Polyisobutylene (weight average molecular weight 80,000) 20 parts Petroleum resin (weight average molecular weight 2,500) 50 parts Rosin liquid resin (weight average molecular weight) 630) 50 parts Zinc oxide 3 parts Zinc chloride 2 parts Zinc isobutylxanthate 4 parts N.N'-diphenyl-p-phenylenediamine 1 part

The above components were dissolved in 700 parts of toluene to prepare a rubber pressure-sensitive adhesive solution. A double-sided adhesive sheet was produced in the same manner as in Example 1 except that this solution was used.

With respect to each of the double-sided adhesive sheets obtained in Examples 1 to 4 and Comparative Examples 1 and 2, the gel fraction of the rubber pressure-sensitive adhesive, the adhesive strength and the curved surface sticking property were measured. .. The results are as shown in Table 1 below. The above-mentioned measurement tests of the gel fraction, the adhesive force and the curved surface sticking property were carried out as follows.

<Gel Fraction> Rubber-based pressure-sensitive adhesive about 0.1
g is wrapped with a porous Teflon membrane (weight b) and weighed. Let this weight be a. This is immersed in 50 ml of toluene at room temperature for 7 days, taken out, and dried at 130 ° C. for 3 hours. Return to room temperature and weigh the weight. Let this weight be c. The gel fraction is [(c-b) / (a-b)] x
It is calculated as 100 (%).

<Adhesive strength> Using a vulcanized rubber plate as an adherend, the adhesive strength (g / 20) was measured according to JIS Z-1528.
mm width) was measured.

<Curved surface pasting characteristics> A vulcanized rubber plate of 10 mm x 100 mm size is wiped dry with a waste cloth and double-sided adhesive sheet is attached.
Attach one side of the toe with one round trip of a 2kg roll. Next, the release paper is peeled off, and the other side is attached to a stainless steel cylinder having a diameter of 200 mm using a 5 kg roll. 50 ° C
After standing for 2 days, the height of floating from the end face was measured.

In the above measurement test, as the vulcanized rubber plate, a chloroprene rubber plate having a thickness of 3 mm (Neo-180 made by Irumagawa Rubber) and an EPT rubber plate having a thickness of 3 mm (EP-made by Irumagawa Rubber- 5065) was used. Also,
The double-sided adhesive sheet of Example 4 was measured such that the rubber pressure-sensitive adhesive layer was in contact with the vulcanized rubber plate side.

[0050]

[Table 1]

As is clear from the results of Table 1 above, according to the double-sided adhesive sheet of the present invention, the vulcanized rubber plate is not subjected to the conventional treatment such as buffing or primer coating. In both cases, it can be seen that very good adhesive properties can be obtained.

Claims (4)

[Claims] 1. The following a to c three components; a) 100 parts by weight of polyisobutylene, butyl rubber or halogenated butyl rubber having a weight average molecular weight of 200,000 to 1.5 million b) Liquid or having a weight average molecular weight of 10,000 to 150,000 30 to 300 parts by weight of semi-liquid rubber c) Contains 30 to 300 parts by weight of a tackifier or / and a softening agent having a weight average molecular weight of less than 10,000 as an essential component and a gel fraction of 10 to
A rubber-based pressure-sensitive adhesive characterized by being in the range of 40%. 2. The rubber-based pressure-sensitive adhesive according to claim 1, wherein the liquid or semi-liquid rubber of the component b is polyisobutylene. 3. Adhesive sheets having a layer of the rubber-based pressure-sensitive adhesive according to claim 1 or 2 on both sides of a base material. 4. An adhesive sheet in which a layer of the rubber-based pressure-sensitive adhesive according to claim 1 or 2 is provided on one surface of a base material, and an acrylic-based pressure-sensitive adhesive layer is provided on the other surface. Kind.