JP3075369B2 - Pressure-sensitive adhesive for vulcanized rubber molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive used for bonding a vulcanized rubber molded product made of natural rubber, chloroprene rubber, EPT (ethylene-propylene-terpolymer) rubber or the like.

[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 amount of adhesion inhibiting substances such as various fillers, vulcanizing agents, and oil components as a compound, and a mold from a press die is used in the step of vulcanizing the rubber molded product. Since a release agent such as silicone oil is used to improve 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 a vulcanized rubber molded product is first subjected to buffing, followed by solvent washing and primer application, and then a film-shaped pressure-sensitive adhesive is laminated thereon. Therefore, a method that is used when adhesively fixing to another adherend is employed.

[0006]

However, the above-described treatments such as buffing and primer application not only increase the number of steps, but also cause the buff powder and solvent to scatter, thereby deteriorating the working environment. In this case, there is a problem that the degree of buffing tends to vary, and accordingly, the adhesive strength also varies.

In view of the above circumstances, the present invention provides a pressure-sensitive material capable of obtaining 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 an adhesive.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, by using a specific polymer as a main component of an adhesive, a vulcanized rubber molded product can be produced by a conventional method. It has been found that they can be sufficiently bonded without performing such treatments as buffing and primer application, and have completed the present invention.

That is, the present invention provides a) S ₁ -I ₁ -S
Type ₂ block copolymer (S ₁ and S ₂ are styrene polymer blocks, I ₁ is an isoprene polymer block, and S ₁ and S
₍₂₎ The number average molecular weight is 8000 or more.)
And 60 _{wt%, b) S 3 -I 2} -S 4 type block copolymer (S _3, S ₄
Is a styrene polymer block, I ₂ is an isoprene polymer block, the number average molecular weight of S ₃ is 8000 or more, and the number average molecular weight of S ₄ is 5,000 or less) and / or S
₅ -I ₃ type block copolymer (S ₅ is styrene polymer block, I ₃ in the isoprene polymer block, the number average molecular weight of S ₅ is more than 8000) 90-40% by weight of a mixed block copolymer The polymer is a main component, and the tackifier resin 5 is used per 100 parts by weight of the mixed block copolymer.
The present invention relates to a pressure-sensitive adhesive for vulcanized rubber molded articles , wherein a rubber-based pressure-sensitive adhesive composition containing 0 to 200 parts by weight is used.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The mixed block copolymer of the present invention comprises a mixture of the above components a and b having a high affinity for a vulcanized rubber molded product. Both components are used in combination because they provide a large cohesive force that can withstand repulsion, and the component b provides fluidity that exhibits selective wettability by eliminating the adhesion inhibitory substance on the vulcanized rubber surface layer. By doing so, sufficient adhesive strength can be obtained without subjecting the vulcanized rubber molded product to a conventional treatment such as buffing or primer application.

The S ₁ -I ₁ -S ₂ type block copolymer of the component a is a styrene polymer block S ₁ ,
The number average molecular weight of S ₂ are both 8000 or more, and preferably will be from 10,000 to 30,000. here,
If at least _one of the number average molecular weights of S ₁ and S ₂ is less than 8,000, a sufficient cohesive force that can withstand the repulsion of the vulcanized rubber molded product cannot be obtained. The number average molecular weight of the isoprene polymer block I _1, depending on the desired properties of the adhesive, the number average molecular weight of the block copolymer is within the range of a 50,000 to 400,000 is appropriately set.

The [0012] b _component, either or both or S 3 _-I 2 -S ₄ type block copolymer or _S 5 -I ₃ type block copolymer. Of _these, S 3 -I
₂ -S ₄ type block copolymer has a number average molecular weight of one of the styrene polymer block S ₃ to configure this is 8000
Or more, preferably next to 10,000 to 30,000, and number average molecular weight of the other styrene polymer block _{S 4} 5
000 or less, preferably 1000 to 3000.

In the above S ₃ -I ₂ -S ₄ type block copolymer, if the number average molecular weight of S ₃ is less than 8000 or the number average molecular weight of S ₄ exceeds 5000, the vulcanized rubber Sufficient cohesive strength to withstand the repulsion of the molded article cannot be obtained, and wettability to the surface of the molded article is impaired. The number average molecular weight of the isoprene polymer block I _2, depending on the desired properties of the adhesive, the number average molecular weight of the block copolymer is within the range of a 50,000 to 400,000 is appropriately set.

The S ₅ -I ₃ type block copolymer is as follows:
The number average molecular weight of the styrene polymer blocks _{S 5} constituting this is 8000 or more, preferably from 10,000 to 3,000
Is 0 and becomes one, the number average molecular weight of the _{S 5} 800
If it is less than 0, a large cohesive force that can withstand the repulsion of the vulcanized rubber molded product cannot be obtained. The number average molecular weight of the isoprene polymer block _{I 3,} within the number-average molecular weight of the block copolymer is from 50,000 to 400,000, is suitably set.

Each of the block copolymers constituting the components a and b can be obtained by a known living anion polymerization method using a lithium-based initiator. At that time, for example, the triblock type,
Styrene polymer block, isoprene polymer block,
The styrene polymer block may be synthesized by successively reacting in order, or the styrene polymer block and the isoprene polymer block may be separately synthesized, and then combined using a coupling agent into a triblock structure. Is also good.

In the mixed block copolymer of the present invention,
The mixing ratio of the components a and b is such that the component a is 10 to 60% by weight and the component b is 90 to 40% by weight, particularly preferably the component a is 20 to 50% by weight and the component b is 80 to 50% by weight.
It is preferable to set the ratio to be the weight%. If it is outside this range, the wettability to the surface of the vulcanized rubber molded product will be reduced, or sufficient cohesive strength to withstand the repulsion of the vulcanized rubber molded product will not be obtained.

In the present invention, the above-mentioned mixed block copolymer is used as a main component, and a tackifier resin is added thereto. As the tackifying resin, any conventionally known liquid or solid resin at normal temperature can be used, for example, terpene resin, terpene phenol resin, terpene aromatic resin, cumarone indene resin, styrene resin, Petroleum resin, phenolic resin, xylene resin,
Rosin-based resins and the like can be mentioned, and these can be used in combination of two or more as necessary.

This tackifying resin is used in an amount of 50 to 200 parts by weight, particularly preferably 70 to 130 parts by weight, based on 100 parts by weight of the above mixed block copolymer.
If the amount is less than 50 parts by weight, it is difficult to impart good adhesive strength to the vulcanized rubber, and if it is more than 200 parts by weight, the cohesive strength is inferior, and in any case, good results cannot be obtained in the adhesive properties to the vulcanized rubber.

The rubber-based pressure-sensitive adhesive composition of the present invention comprises:
In addition to the above-mentioned mixed block copolymer and tackifying resin as essential components, various polymer components other than the above-mentioned mixed block copolymer, such as elastomers and / or plastomers, are included for the purpose of minutely adjusting the adhesive properties. Can be.

Examples of such polymer components include styrene-butadiene-styrene type block copolymer, styrene-isoprene-styrene type hydrogenated block copolymer, styrene-butadiene-styrene type hydrogenated block copolymer, Although butyl rubber and polyisobutylene are preferably used, other polymers other than the rubber component such as ethylene-vinyl acetate copolymer may be used.

The pressure-sensitive adhesive composition of the present invention further comprises a process oil, a polyester plasticizer, polybutene,
A softening agent such as a liquid rubber may be included as needed.
The amount of the softener is preferably 75 parts by weight or less, usually 5 to 75 parts by weight, based on 100 parts by weight of the mixed block copolymer of the components a and b.

Further, the pressure-sensitive adhesive composition of the present invention includes:
Various additives such as antioxidants, UV absorbers, fillers, pigments, and extenders which are conventionally known, which are added to the pressure-sensitive adhesive, can be blended. These usage amounts may be ordinary usage amounts.

The rubber-based pressure-sensitive adhesive composition of the present invention thus constituted may be a solventless hot-melt coating type or a solution type using an appropriate organic solvent such as toluene. Further, it can be an aqueous or non-aqueous emulsion type. In the case of a solution type, since the solution viscosity is lower than that of a conventional type using natural rubber or the like as a base polymer, high solid coating becomes possible, which is industrially advantageous.

When the rubber-based pressure-sensitive adhesive composition of the present invention, which is of various types, is used, each type is converted into a final form of pressure-sensitive adhesive from a vulcanized rubber molded product. Although it may be applied directly to the adherend, it is usually preferable to use it as a film-shaped pressure-sensitive adhesive layered on an appropriate substrate.

In this case, a layer may be formed on only one side of the substrate, but for the purpose of bonding the vulcanized rubber molded article to another adherend, a layer is formed on both sides of the substrate. It is desirable to use an adhesive sheet. When producing this double-sided adhesive sheet, for example, the above-mentioned adhesive composition is once applied and dried on a release paper to form a layer, two of which are prepared, and these may be attached to both sides 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 adhesive component from one side to the other side of the film can be prevented, a decrease in the adhesive force over time is suppressed.

The thickness of the adhesive layer provided on the substrate, that is, the layer of the rubber-based pressure-sensitive adhesive composition, is preferably about 10 to 400 μm on one side, but is not limited thereto. Without being determined, it can be determined appropriately according to the purpose of use. With such an adhesive layer, a large adhesive force of generally 800 g / 20 mm width or more can be obtained with respect to a vulcanized rubber molded product such as chloroprene rubber or EPT rubber.

When a double-sided adhesive sheet is obtained, a layer of the rubber-based pressure-sensitive adhesive composition is provided only on one surface of the base material, and another adhesive composition, particularly an acrylic pressure-sensitive adhesive, is provided on the other surface. When the layer of the adhesive composition is provided, any modification may be adopted.

According to such an embodiment, the adhesion to the vulcanized rubber molded article can utilize the layer of the rubber-based pressure-sensitive adhesive composition, and the adhesion to other adherends can be performed by the above-mentioned acrylic pressure-sensitive adhesive. The availability of layers of the composition and the like will result in more desirable adhesive properties depending on the intended use.

The layer of the acrylic pressure-sensitive adhesive composition contains an appropriate coloring pigment in the same manner as the layer of the rubber-based pressure-sensitive adhesive composition. May be prevented by the coloring. For the same purpose, the base material itself may be colored.

[0031]

As described above, in the present invention, a specific mixed block copolymer is used as a main component of the adhesive, so that the molded article is particularly curved when bonding the vulcanized rubber molded article. A pressure-sensitive adhesive exhibiting a sufficient adhesive strength can be obtained without applying conventional treatments such as buffing and primer application when sticking to an adherend having the following.

[0032]

Next, examples of the present invention will be specifically described in comparison with comparative examples. Hereinafter, "parts" means parts by weight. The block copolymers A to C used in the following Examples and Comparative Examples were synthesized by the following method.

<Block copolymer A> 500 parts of dehydrated and purified cyclohexane and 0.03 part of tetrahydrofuran were charged into a reaction autoclave under a nitrogen atmosphere, and the internal bath was heated to 60 ° C. Next, a hexane solution containing 0.02 parts of n-butyllithium was added, and then 7.5 parts of styrene was added, followed by polymerization for 100 minutes. Next, 85 parts of isoprene was added and polymerization was carried out for 100 minutes. Finally, 7.5 parts of styrene was added and polymerization was carried out for 100 minutes.

The polymer solution obtained in this manner was added with 2
Addition of 0.6 part of 6-di-tert-butyl-p-cresol to give S ₁ -I ₁ -S ₂ type block copolymer A
Was obtained. The number average molecular weight of each block portion of the block copolymer A, was measured at each polymerization step, _{S 1} is 21000, _{I 1} is 240000, S
₂ was 21,000.

<Block Copolymer B> The block copolymer A described above was changed except that the amount of the monomer and the amount of the polymerization initiator were changed.
By polymerizing in the same manner as to _obtain a solution containing the block copolymer B of S 3 _-I 2 -S ₄ type. The number average molecular weight of each block portion of the block copolymer B is, S ₃ 2000
0, _{I 2} is 130000, _{S 4} is Atsuta in 3000.

<Block Copolymer C> The above block copolymer A was used except that the amount of monomer and the amount of polymerization initiator were changed.
By polymerizing in the same manner as to obtain a solution containing S ₅ -I ₃ type block copolymer C. The number average molecular weight of each block portion of the block copolymer C is, _{S 5} is 15000, _{I 3}
Was 85,000.

Example 1 30 parts of the block copolymer A and 70 parts of the block copolymer B were mixed, and the mixed block copolymer was further mixed with C _5.
100 parts of a petroleum-based tackifying resin (softening point: 100 ° C.) and 2 parts of a phenolic antioxidant are blended, mixed well, and diluted with toluene so that the solid content becomes 50% by weight.
A rubber-based pressure-sensitive adhesive solution was prepared.

This pressure-sensitive adhesive solution was applied to a thickness of 25 μm.
And dried on both sides of the polyester film so that the thickness after drying is 60 μm each, and then 20 mm
The sheet was cut into a width to produce a double-sided adhesive tape.

Example 2 The same procedure was followed as in Example 1 except that the amount of the block copolymer A was changed to 50 parts and the amount of the block copolymer B was changed to 50 parts. A pressure-sensitive adhesive solution was prepared, and a double-sided adhesive tape was produced in the same manner as in Example 1 using this solution.

Example 3 A block copolymer A50 was used as the mixed block copolymer.
And a rubber-based pressure-sensitive adhesive solution was prepared in the same manner as in Example 1, except that 50 parts by weight of the block copolymer C were used, and a double-sided adhesive tape was prepared in the same manner as in Example 1 using this solution. Was prepared.

Comparative Example 1 A rubber-based pressure-sensitive adhesive solution was prepared in the same manner as in Example 1 except that the amount of the block copolymer A was changed to 100 parts and no block copolymer B was used. A double-sided adhesive tape was prepared in the same manner as in Example 1 using this solution.

Comparative Example 2 A rubber-based copolymer was prepared in the same manner as in Example 1 except that the amount of the block copolymer B was changed to 100 parts and neither the block copolymer A nor the tackifying resin was used. Was prepared, and a double-sided adhesive tape was produced in the same manner as in Example 1 using this solution.

With respect to each of the double-sided adhesive tapes obtained in Examples 1 to 3 and Comparative Examples 1 and 2, the adhesive strength and the curved surface sticking characteristics were measured in the following manner.

<Adhesive Strength> Using a vulcanized rubber plate as an adherend, an adhesive force (g / 2) according to JIS Z-1528.
0 mm width).

<Character Pasting Characteristics> 10 mm × 100 m
A vulcanized rubber plate having a size of m is wiped dry with a rag, and one surface side of the double-sided adhesive tape is bonded with one reciprocation of 2 kg 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. After standing at 50 ° C. for 2 days, the height of the lift from the end face was measured.

In the above two measurement tests, a vulcanized rubber plate was a chloroprene rubber plate having a thickness of 3 mm (Neo-180 manufactured by Irumakawa Rubber) and an EPT having a thickness of 3 mm.
A rubber plate (EP-5065 made by Iruma Rubber) was used.

The above measurement results were as shown in Table 1 below. In Table 1, as a reference example,
After applying a chloroprene rubber-based primer treatment to the vulcanized rubber plate as the adherend, the results of examining the adhesive strength and the curved surface sticking characteristics in the same manner as described above using an acrylic double-sided adhesive tape were also described. .

The acrylic double-sided adhesive tape used in the above reference example was produced as follows. First, acrylic acid n
-Butyl 70 parts, 2-ethylhexyl acrylate 27
, 3 parts of acrylic acid and 233 parts of ethyl acetate are subjected to radical polymerization by a conventional method to obtain a polymer solution containing an acrylic polymer having a weight average molecular weight of 550,000 and a solid content of 30% by weight. And an acrylic polymer 10
Rosin-based tackifying resin (softening point 100 ° C) for 0 parts
Add and mix 30 parts. Next, the above-mentioned mixed solution was applied to both sides of a polyester film having a thickness of 25 μm so as to have a thickness of 60 μm after drying, dried, and then cut into the same tape width as in Example 1. And an acrylic double-sided adhesive tape.

[0049]

[Table 1]

As is clear from the results shown in Table 1 above, according to the double-sided adhesive tape of the present invention, the vulcanized rubber plate can be treated without performing conventional treatments such as buffing and primer application. It can be seen that very good adhesive properties can be obtained.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-231070 (JP, A) JP-A-61-278578 (JP, A) JP-A-60-226579 (JP, A) JP-A 52-1982 140544 (JP, A) JP-A-52-140545 (JP, A) Japanese Utility Model Application Laid-Open No. 2-140946 (JP, U) Japanese Translation of PCT Application No. Hei 6-501975 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) C09J 153/02 C09J 7/02

Claims (3)

(57) [Claims] 1. A) S ₁ -I ₁ -S ₂ type block copolymer (S ₁ and S ₂ are styrene polymer blocks, I ₁ is an isoprene polymer block and the number average molecular weight of S ₁ and S ₂ and 10 to 60 wt% both at 8000 or _{more), b) S 3 -I 2 -S} 4 type block copolymer (S _3, S ₄
Is a styrene polymer block, I ₂ is an isoprene polymer block, the number average molecular weight of S ₃ is 8000 or more, and the number average molecular weight of S ₄ is 5,000 or less) and / or S
₅ -I ₃ type block copolymer (S ₅ is styrene polymer block, I ₃ in the isoprene polymer block, the number average molecular weight of S ₅ is more than 8000) 90-40% by weight of a mixed block copolymer The polymer is a main component, and the tackifier resin 5 is used per 100 parts by weight of the mixed block copolymer.
A pressure-sensitive adhesive for vulcanized rubber molded articles , comprising a rubber-based pressure-sensitive adhesive composition containing 0 to 200 parts by weight. 2. A film-like vulcanizer comprising a substrate and a layer of the rubber-based pressure-sensitive adhesive composition according to claim 1 provided on both sides.
Pressure-sensitive adhesive for rubber molded products . 3. A film in which a layer of the rubber-based pressure-sensitive adhesive composition according to claim 1 is provided on one surface of a substrate and a layer of an acrylic pressure-sensitive adhesive composition is provided on the other surface. Shape
Pressure-sensitive adhesive for vulcanized rubber molded products .