JP3145742B2 - Rubber-based pressure-sensitive adhesive and its adhesive sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention 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 bonding a vulcanized rubber molded product made of rubber or the like, and an adhesive sheet thereof.

[0002]

2. Description of the Related Art Vulcanized rubber molded articles of this kind are widely used as automobile parts, home appliances, OA equipment members, and various other industrial products.

[0003] However, these rubber molded products contain a large number of adhesion inhibitors such as various fillers, vulcanizing agents, and oil components as a compound, and the rubber molded product is vulcanized from a press die in a step of vulcanizing the rubber molded product. Since a release agent such as silicone oil is used to improve mold release, the adhesiveness of the molded product surface is poor.

Moreover, since these vulcanized rubber molded articles have high elasticity, when they are attached to a curved surface, they are bonded and fixed in a state where stress is applied by the above-mentioned elastic action. However, due to this and the poor adhesiveness of the molded article surface, there is a problem that the molded article is easily peeled off after the adhesive fixation.

[0005] For this reason, conventionally, the surface to be adhered of the vulcanized rubber molded product is first buffed, then the solvent is washed and the primer is removed.
A method has been adopted in which a coating is applied, a pressure-sensitive adhesive sheet is attached on the adhesive, and the adhesive sheet is fixed to another adherend.

[0006]

However, the above-mentioned processes such as buffing and primer coating not only increase the man-hours but also cause the buff powder and the solvent to scatter, thereby deteriorating the working environment. In the process, there is a problem that the degree of buffing tends to fluctuate, and accordingly, the adhesive strength also fluctuates.

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a rubber-based rubber composition that can obtain a sufficient adhesive strength without subjecting a vulcanized rubber molded product to a conventional treatment such as buffing or primer application. It is intended to provide a pressure-sensitive adhesive and its adhesive sheet.

[0008]

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

That is, the present invention relates to 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) weight-average molecular weight of 10,000 to 15 30 to 300 parts by weight of 10,000 liquid or semi-liquid rubber c) 30 to 300 parts by weight of a tackifier or / and softener having a weight average molecular weight of less than 10,000 as an essential component, and a gel fraction of 10 to 300 parts by weight.
The present invention relates to a rubber-based pressure-sensitive adhesive characterized by being in a range of 40%. Further, the present invention is formed by providing a layer of rubber-based pressure-sensitive adhesive on one or both sides of a substrate adhesion
It concerns the sheet . In addition, the above "adhesion sheet"
Includes adhesive tape. In this sense, this specification
In the following, the above "adhesive sheets" will be referred to as "adhesive sheets"
Sometimes.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The rubbery polymer of the component a in the present invention has a high affinity for vulcanized rubber molded articles, and exhibits a selective wettability by eliminating an adhesion inhibitory substance on the surface layer. Examples of-used are polyisobutylene, a homopolymer of isobutylene, butyl rubber, a copolymer of isobutylene and 1 to 3% by weight of isoprene, and halogenated butyl rubber obtained by brominating or chlorinating this butyl rubber. .

The molecular weight of the rubbery polymer must be in the range of 200,000 to 1.5 million in weight average molecular weight.
Particularly preferably, it is in the range of 300,000 to 1,000,000.
If it is less than 200,000, the cohesive force of the adhesive cannot be sufficiently obtained, and when the vulcanized rubber molded product is to be stuck on a curved surface, the adhesive tends to be peeled off after bonding and fixing. On the other hand, if it exceeds 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.

The liquid or semi-liquid rubber of the component b in the present invention includes, for example, polyisobutylene, polybutene, ethylene propylene rubber and the like. Among them, 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 enhance the wettability of the vulcanized rubber molded article.

The term "liquid or semi-liquid" means a state at normal temperature (25 ° C.), and the term "semi-liquid" means a state in which a very slow but fluid phenomenon is exhibited. Means

The molecular weight of such a liquid or semi-liquid rubber must be in the range of 10,000 to 150,000 by weight average molecular weight, and particularly preferably in the range of 20,000 to 120,000. . If it is smaller than 10,000, the cohesive force of the adhesive cannot be sufficiently obtained, and when the vulcanized rubber molded product is to be stuck on a curved surface, the adhesive tends to be peeled off after being fixed. Conversely, if it is larger 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 the component (b) is based on 100 parts by weight of the rubbery polymer of the component (a).
It is necessary to be in the range of 30 to 300 parts by weight, particularly preferably in the range of 50 to 150 parts by weight. 30
When 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, so that it is difficult to obtain sufficient wetting with the vulcanized rubber molded product. Conversely, if the amount is more than 300 parts by weight, the cohesive force of the adhesive cannot be sufficiently obtained, and when the vulcanized rubber molded product is pasted on a curved surface, the adhesive tends to be peeled off after the adhesive is fixed.

The tackifier, which is one of the component c in the present invention, includes terpene resins, terpene-pheno-
In addition to solid tackifiers at room temperature such as toluene-based resins, petroleum-based resins, styrene-based resins, cumarone-indene resins, xylene-based resins, and phenol-based resins, various tackifiers that are liquid at room temperature can be used. . Examples of the softening agent, which is another component of the component c, include low-molecular-weight liquid rubber such as process oil, polyester plasticizer, and polybutene.

The molecular weight of the component (c) must be less than 10,000 in terms of weight average molecular weight.
It is good to 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 and / or the softening agent used as the component (c) depends on the amount of the rubbery polymer of the component (a).
It is necessary to be in the range of 30 to 300 parts by weight per 100 parts by weight, particularly preferably in 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. Conversely, if the amount is more than 300 parts by weight, the cohesive force of the adhesive cannot be sufficiently obtained, and when the vulcanized rubber molded product is pasted on a curved surface, the adhesive tends to be peeled off after the adhesive is fixed.

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

The rubber-based pressure-sensitive adhesive of 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 the rubber-based pressure-sensitive adhesive of this type, if the gel fraction is less than 10%, the cohesive force of the adhesive cannot be sufficiently obtained, and the vulcanized rubber molded product is stuck on a curved surface. In some cases, it is easy to peel off after bonding and fixing. Conversely, if it exceeds 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, a
A method of appropriately crosslinking a rubber-based pressure-sensitive adhesive containing three components c is effective. Examples of the crosslinking method include a method of crosslinking with a peroxide, a method of crosslinking with quinone dioxime and a peroxide, and a method of crosslinking with zinc oxide and various accelerators. 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 rubbery polymer as the component a is a halogenated butyl rubber.

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

In this use, the above-mentioned adhesive solution may be applied directly to an adherend formed of a vulcanized rubber molded product, but usually, a sheet-like material formed on an appropriate substrate is used. It is preferably used as an adhesive sheet in the form of a film, a tape, or the like. In this case, a layer may be formed on only one surface of the substrate, but for the purpose of bonding the vulcanized rubber molded product to another adherend, a layer is formed on both surfaces of the substrate, so-called double-sided bonding. It is desirable to use sheets.

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

The base material may be a porous base material such as non-woven fabric, woven fabric, paper, or the like, or a plastic film such as polyester film, polyethylene film, polypropylene film, polyvinyl chloride film, and the like.
Those having a thickness of about 200 μm are used. When using plastic film, if you leave it for a long time after using it,
Since the transfer of the adhesion-inhibiting component from one side to the other side of the film can be prevented, a decrease in the adhesive force over time is suppressed. When an undercoating treatment is applied to these substrates before providing the adhesive layer, the anchoring force of the adhesive is improved.

The thickness of the adhesive layer provided on the substrate, that is, the layer of the rubber-based pressure-sensitive adhesive, is preferably about 10 to 400 μm on one side, but is not limited thereto. Instead, it can be determined appropriately according to the purpose of use.

When a double-sided adhesive sheet is obtained, a layer of the rubber-based pressure-sensitive adhesive is provided only on one surface of the substrate,
Modifications may be made whenever another layer of an adhesive, especially an acrylic pressure-sensitive adhesive, is provided on the other side.

According to this embodiment, the rubber-based pressure-sensitive adhesive layer can be used for bonding to the vulcanized rubber molded article, and the above-mentioned acrylic pressure-sensitive adhesive layer or the like can be used for bonding to other adherends. As a result, more desirable adhesive properties may be obtained depending on the purpose of use. Note that the acrylic pressure-sensitive adhesive layer may appropriately contain various additives such as coloring pigments as in the case of the rubber pressure-sensitive adhesive layer.

[0030]

As described above, according to the present invention, as the essential components of the adhesive, three kinds of polymer components having a specific molecular weight such as a rubbery polymer and a tackifier are used in combination, and these components are used. When the vulcanized rubber molded article is bonded, particularly when the molded article is attached to an adherend having a curved surface, by setting the gel fraction of the entire adhesive including the Polishing and primer
It is possible to obtain a rubber-based pressure-sensitive adhesive exhibiting sufficient adhesive strength and its adhesive sheets without applying treatment such as coating.

[0031]

Next, examples of the present invention will be specifically described in comparison with comparative examples. Hereinafter, “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 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 on a separator using an applicator so that the thickness after drying was 70 μm, and dried at 100 ° C. for 3 minutes.

Next, two layers of the rubber-based pressure-sensitive adhesive formed on the separator were prepared, and these were bonded to both sides of a nonwoven fabric having a thickness of 50 μm.
For 2 days to produce 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 part cobalt naphthenate 0.05 part

The above components were dissolved in 590 parts of toluene to prepare a rubber-based pressure-sensitive adhesive solution. Using this solution, a double-sided adhesive sheet was prepared 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 isopropyl xanthate 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 prepared 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 233 of ethyl acetate
A part of the monomer solution was radically polymerized by a conventional method to obtain a polymer solution containing an acrylic polymer having a weight average molecular weight of 600,000. To 100 parts of the acrylic polymer, 3 parts of a trifunctional low molecular weight isocyanate compound was added and mixed to prepare a solution of an acrylic pressure-sensitive adhesive.

Next, the solution of the rubber-based pressure-sensitive adhesive of Example 1 was applied to one surface of a polyester film having a thickness of 12 μm so that the thickness after drying became 70 μm.
After drying at a temperature of 60 ° C. for 3 minutes, it was further left at 60 ° C. for 2 days. Thereafter, the solution of the acrylic pressure-sensitive adhesive was dried on the other surface of the polyester film to a thickness of 70% after drying.
μm, dried at 100 ° C for 3 minutes,
A double-sided adhesive sheet was produced.

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 disulphide 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 prepared 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-based pressure-sensitive adhesive solution. A double-sided adhesive sheet was prepared in the same manner as in Example 1 except that this solution was used.

With respect to each double-sided adhesive sheet obtained in each of Examples 1 to 4 and Comparative Examples 1 and 2, the gel fraction of the rubber-based pressure-sensitive adhesive, the adhesive strength, and the characteristics of attaching to a curved surface were measured. . The results were as shown in Table 1 below. In addition, the measurement test of the above-mentioned gel fraction, adhesive strength, and curved surface sticking characteristics was performed in the following manner.

<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 at this time. This weight is defined as c. The gel fraction was [(c−b) / (ab)] ×
It is calculated as 100 (%).

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

<Curved surface sticking characteristics> A vulcanized rubber plate having a size of 10 mm x 100 mm is wiped dry with a rag, and a double-sided adhesive sheet is applied.
Attach one side of the roll with one round of 2kg roll. Next, the release paper is peeled off, and the other side is bonded to a 200 mm diameter stainless steel cylinder using a 5 kg roll. 50 ℃
After 2 days, the height of the lift from the end face was measured.

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

[0050]

[Table 1]

As is clear from the results shown in Table 1, 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 application. In both cases, it can be seen that very good adhesive properties can be obtained.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-48-745 (JP, A) JP-A-50-86538 (JP, A) JP-A-52-53950 (JP, A) 81124 (JP, B2) JP 34-975 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09J 123/20-123/22 C09J 7/02-7/04 C09J 121/00-121/02 C09J 123/28

Claims (4)

(57) [Claims] 1. 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 liquid or a liquid having a weight-average molecular weight of 10,000 to 150,000 30 to 300 parts by weight of semi-liquid rubber c) 30 to 300 parts by weight of a tackifier or / and a softener having a weight average molecular weight of less than 10,000 as an essential component and a gel fraction of 10 to 300 parts by weight.
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. A comprising a layer of rubber-based pressure sensitive adhesive according to both sides of the substrate to Claim 1 or 2 is provided adhesive sheet - and. 4. An adhesive sheet comprising: a layer of the rubber-based pressure-sensitive adhesive according to claim 1 provided on one surface of a substrate; and an acrylic pressure-sensitive adhesive layer provided on the other surface . .