JPS60124235A - Adhesion between layer of rubber - Google Patents

Abstract

PURPOSE:To restrain releasing agent from creeping into the gap between rubber materials and to prevent faulty adhesion by a method wherein rubber materials are layered one upon another at their adhesive areas, the adhesive areas are covered with specific tacky tape and then releasing agent is sprayed, compressed and vulcanized. CONSTITUTION:Rubber materials composed mainly of halogenated butyl rubber such as chlorinated butyl rubber are layered one upon another at their adhering areas. Then, these adhering areas are covered with tacky tape composed of a film layer consisting mainly of thermoplastic polymer such as transpolyisoprene etc. where the storage elastic modulus (G') measured at 50 deg.C, by 15Hz and at 1% strain is 5X10<7> dyne/cm<2> min. and a tacky adhesive layer. Further, releasing agent is sprayed by a spray gun etc. on the rubber material surface dried sufficiently, vulcanized and adhered to improve the adhesion between rubber materials.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical field to which the invention relates) The present invention relates to a rubber-to-rubber adhesion method for adhering rubber materials, and in particular to improvements in joint adhesion methods for inner liners in tire manufacturing processes. be.

(Prior art) Conventionally, butyl rubber or a blend of butyl rubber and natural rubber (NR) has been used as the inner liner material, but in recent years, tires have become more radial, tubeless, and have longer lifespans and higher performance. As technology progressed, rubbers that were layered and air impermeable were required. For this reason, halogenated butyl rubber alone or blended with natural rubber has come to be used as an inner liner material.

As a result, the adhesion of the overlap joint surface is insufficient, and the release agent flows into the unbonded area, causing poor adhesion of the inner liner after vulcanization, and damage to the inner liner that progresses during driving, resulting in air impermeability and tire This has a negative effect on the durability of the product.

Conventionally, countermeasures against this problem include sacrificing the excellent air impermeability of halogenated butyl rubber to increase the ratio of NR used, and when applying a mold release agent, the joint surface is covered with a vinyl chloride sheet, etc. A method was proposed. However, when coating the joint surface, if the sheet is vulcanized with the sheet attached after application of the release agent, the sheet may adhere to the vulcanized blinder, and cracks in the sheet may cause poor tire appearance. For this reason, it is necessary to remove the cover, resulting in an increase in the number of man-hours.

In addition, methods have been used to co-vulcanize the joint by covering the joint with a tape made of the same rubber as the inner liner, but since halogenated butyl rubber is in a rubber state at around room temperature, workability has been affected. It is not possible to obtain a good thin tape, and a step occurs at the joint surface between the inner liner and the halogenated butyl rubber cover tape.As a result, it is not possible to prevent the release agent from getting caught, resulting in problems such as poor adhesion. It is occurring.

Furthermore, a method of crimping the joint surface with an electric knife to promote adhesion has been used, but the adhesion was not completely peeled off.
It had the disadvantage of causing poor adhesion.

(Disclosure of the Invention) As a result of extensive research aimed at solving the drawbacks of the above-mentioned conventional methods, the present inventors discovered that a mold release agent is used when bonding rubber materials containing halogenated butyl rubber as a main component. A film made of a material based on a thermoplastic polymer having a storage modulus (G') of 5 x 107 dynes/cm" or more when measured at 50°C, 115 Hz, and 1% strain on the joints of rubber materials before being sprayed. The present invention was achieved by confirming that coating with an adhesive tape composed of a layer and an adhesive layer prevents the release agent from flowing into the unbonded areas, thereby preventing poor adhesion.

In the present invention, a rubber containing halogenated butyl rubber as a main component is one containing chlorinated butyl rubber and/or brominated butyl rubber as a rubber component, and preferably 40 parts by weight of these halogenated butyl rubbers in 100 parts by weight of rubber. Part or more of the remaining natural rubber, polybutadiene rubber, styrene-butadiene copolymer rubber,
It is made of synthetic isoprene rubber, acrylonitrile-butadiene copolymer rubber, butyl rubber, etc. alone or in a blend.

The method of the present invention involves superimposing the bonding portions of the rubbers containing halogenated butyl rubber as a main component, and covering this bonded portion with an adhesive tape consisting of a film layer as a base material and an adhesive layer. , a method in which a release agent is sprayed on the rubber surface and pressure vulcanization is performed, and the film layer of the adhesive tape used at this time has a storage elastic modulus of 5 x 10 when measured at 50°C, 115 Hz, and 1 inch strain as described above. It is made of a substance of dyne/C- or higher. The material forming such a film layer may contain 50% by weight or more of a thermoplastic polymer, such as transpolyisoprene, crystalline 1,2-polybutadiene, styrene-butadiene block polymer, or a blend thereof. Preferably. In particular, the above-mentioned transpolyisoprene, crystalline 1,2-polybutadiene, and styrene-butadiene copolymer are in a glass or crystalline state at room temperature, and are rubbery and have free fluidity under vulcanization temperature conditions. It is particularly preferable for use as a base material for adhesive tapes, and if a material containing 50% or more of these rubbers by weight and having the above-mentioned storage elastic heavy chain is used, it will not be a general-purpose polymer for tires at around room temperature. A thin tape with a thickness of 2 to 500 μm, which could not be obtained previously, was obtained, and this tape has excellent workability and can prevent cracks from forming from poorly bonded portions of the inner liner during use of the tire.

Furthermore, the storage elastic modulus value of the above substance is 5X107 dynes/cmQ
If it is less than that, it is impossible to obtain the above-mentioned thin film of 2 to 500 μm required in the present invention.

Next, the adhesive layer of the adhesive tape uses rubber elastomers such as natural rubber, synthetic polyisoprene rubber, styrene-butadiene copolymer, polyisobutylene, butyl rubber, butadiene-ac IJO nitrile rubber, polyvinyl alkyl ether, and polyacrylate. If necessary, one type or a mixture of two or more of rosin, rosin ester, other rosin derivatives, polyterpene resin, oil-soluble phenol resin, petroleum hydrocarbon resin, etc. can be used as a tackifier. Done 1. '-4' Also, fillers can be freely selected from zinc oxide, titanium oxide, calcium carbonate, clay, and the like. Furthermore, a softener and an anti-aging agent can also be used if necessary.

In the above-mentioned adhesive tape consisting of a film layer and an adhesive layer, the film portion of the base material is heated at a normal vulcanization temperature (120~
When the inner liner is bonded to the inner liner, it becomes soft and adheres to the bladder, and when removed from the vulcanization pot, the adhesive tape adheres to the bladder surface and peels off from the tire.
It is conceivable that this may have an adverse effect on bladder life.

For this reason, the film layer and/or the adhesive layer of the adhesive tape should contain a vulcanizing agent, a vulcanization accelerator, and a vulcanizing agent consisting of an optional vulcanization accelerator, or carbon black, calcium carbonate, etc. , an inorganic filler such as silicon oxide, or a vulcanizing agent and an inorganic filler.

Adding a vulcanizing agent etc. in this way vulcanizes the adhesive tape and prevents the bladder from adhering when the bladder contracts at the end of vulcanization, and adding the above-mentioned inorganic filler improves the heat resistance of the adhesive tape. In addition, the coefficient of friction on the tape surface is reduced, and the tackiness of the film layer of the adhesive tape is also reduced, preventing it from adhering to the bladder or breaking it, and in both cases, preventing the release agent from getting caught in the adhesive interface. This prevents adhesion failure.

The vulcanizing agent added to the adhesive tape is preferably sulfur, and the amount added is 0.1 to 2.0 parts per 100 parts by weight of the film.
The amount is 5 parts by weight, preferably 0.8 to 1.0 parts by weight. If the sulfur concentration is less than 0.1 part by weight, sufficient vulcanization cannot be obtained to prevent adhesion, which is the purpose of the present invention, and if it exceeds 2.5 parts by weight, the elastic modulus of the inner liner may be partially increased, and the inner liner may As a result of promoting co-vulcanization between the liner and the adhesive tape, cracks generated in the adhesive tape progress to the inner liner, which is undesirable because it reduces the bending fatigue properties of the inner liner.

Next, as a vulcanization accelerator, it is preferable to add cyclohexylbenzothiazole sulfenamide, dibenzothiazyl disulfide, diphenylguanidine, etc.; It does not need to be included in the adhesive tape since the necessary amount is supplied in sufficient quantity.

Further, the vulcanization accelerator can be selected from stearic acid and zinc oxide or zinc stearate.

The amount of the vulcanization accelerator added is 0.2 to 4 parts by weight, preferably 0.4 to 2.5 parts by weight. If the amount of the vulcanization accelerator added is less than 0.2 parts by weight, sufficient vulcanization will not be achieved, and if it is more than 4 parts by weight, the crosslinking density of the surface layer of the inner liner will increase, which is not preferable.

Next, when adding an inorganic filler such as carbon black, calcium carbonate, or silicon oxide to the adhesive tape, 1 to 150 parts by weight, preferably 10 to 90 parts by weight of the inorganic filler is added to 100 parts by weight of the polymer. do. If the inorganic filler is less than 10 parts by weight, the adhesion cannot be reduced;
If it is contained in excess of 0 parts by weight, the adhesive tape becomes hard, and especially when 150 rays are added, the adhesive tape becomes difficult to apply, and while it has excellent heat resistance, it also improves the adhesion and fracture performance against bladders, reducing workability. You can't get the adhesive tape that won't let you.

In the present invention, when an adhesive tape to which a vulcanizing agent, a vulcanization accelerator auxiliary agent, and a vulcanization accelerator are added as required is used for joining rubber materials containing halogenated butyl rubber as a main component, When co-vulcanization occurs with rubber whose main component is halogenated butyl rubber, the breaking strength of the tape is significantly smaller than that of rubber whose main component is halogenated butyl rubber, making it a material that is prone to cracking. As a result, cracks that occur in the film progress to the rubber whose main component is halogenated butyl rubber. This will reduce the fracture resistance of the rubber component. Therefore, in the present invention, in a rubber whose main component is halogenated butyl rubber, the rubber lo Om
In systems containing 90 parts by weight or more of halogenated butyl rubber in the ffi part, if the film layer of the adhesive tape has an isoprene, butadiene, or styrene-butadiene structure, it is difficult to co-add a rubber containing halogenated butyl rubber as a main component, such as an inner liner. The sulfuricity is extremely low, and as a result, there is no concern that cranks generated in the film will progress to the inner liner, and the rubber elastomer that makes up the adhesive layer of the adhesive tape has the characteristic of easily peeling off when the inner liner is stretched. The rubber can be freely selected from natural rubber, styrene-butadiene copolymer, synthetic polyisoprene rubber, polyisobutylene, butyl rubber, butadiene-acrylonitrile rubber, polyvinyl alkyl ether, polyacrylate, and the like.

However, in a rubber whose main component is halogenated butyl rubber, halogenated butyl rubber is contained in 40 parts by weight or more and less than 90 parts by weight per 100 parts by weight of rubber, and other rubber components include natural rubber, styrene-butadiene copolymer,
In systems in which diene polymers such as polybutadiene are used, they are copolymerized with trans-isoprene polymer, crystalline 1,2-polybutadiene, and styrene-e-butadiene block copolymer, which are the main components of the film layer of the base material of the adhesive tape. It has a high vulcanizability, and if cracks occur in the film layer of the adhesive tape, the cracks will progress to the rubber whose main component is halogenated butyl rubber, reducing the fracture resistance of the halogenated butyl rubber. In order to prevent this, in the present invention, in a rubber whose main component is halogenated butyl rubber, 40 parts by weight of halogenated butyl rubber is contained in 100 parts by weight of rubber.
For yarns containing a weight of m or more and less than 90 parts by weight and in which diene polymers such as natural rubber, styrene-butadiene copolymer, and polybutadiene are used as other rubber components, the rubber elastomer constituting the adhesive layer of the adhesive tape As polyisobutylene, polyvinyl alkyl ether, polyacrylate, butyl rubber, number average molecular weight is a
Using a styrene-butadiene copolymer of ooo or less, the co-vulcanization of a rubber mainly composed of halogenated butyl rubber and a film layer of an adhesive tape is eliminated or reduced.

(Example of the invention) The invention will be explained in more detail by the following examples.

Examples Various rubber compositions having the formulations shown in Table 1 were prepared using brominated butyl rubber.
As shown, the thickness (t) is 2.1 mm.

Width (W) 200 mm, length Q 21011111
(7) Produce the unvulcanized com sheet 1 using a 10-inch roll, then use a sharp cutter to make the unvulcanized rubber sheet 45
Cut at an angle (θ) of 20 ml to length (72) and glue together, and then join with adhesive tape 2 with a thickness of 10 μm and a length of 45 mm made of the tape composition shown in Table 2. Cover the area over a length of about 45 cm
Furthermore, with an air spray gun, apply a mold release agent whose main ingredients are calcium carbonate, silicone, and surfactant at approximately 0.029//
Spray at a ratio of cm2, dry thoroughly, and then spray at 155°.
C. Vulcanization was carried out for 20 minutes to obtain a sheet having a thickness of 2jIII.

Furthermore, the breaking strength, breaking elongation, and 800% hydurus of the various rubber compositions shown in Table 1 were measured using JIS No. 3 by punching out sheets with a thickness of 2 mm according to JIS K2SO3. In addition, it was observed with an optical microscope at 100x magnification whether the fracture progressed from the overlap joint surface. The results obtained regarding physical properties and workability are shown in Table 8.1 Table 1 (Effects of the Invention) As explained above, the rubber-to-rubber adhesion method of the present invention:
When vulcanizing and adhering rubber materials whose main component is halogenated butyl rubber, the bonding area is covered with an adhesive tape consisting of a specific film layer and an adhesive layer, and then a release agent is sprayed on the rubber surface and vulcanization adhesion is performed. This prevents the entrapment of substances that hinder vulcanization, such as mold release agents, and significantly improves vulcanization adhesion, and from the results in Table 8, prevents the adhesive surface from becoming the core of fracture progression. At the same time, it is clear that various physical properties are significantly improved.

[Brief explanation of the drawing]

Figure 1a is a perspective view of the test sample used in the examples, in which unvulcanized rubber sheets are stacked together, and Figure 1a is a side view of the sample in which the joint of the sample in Figure 1a is covered with adhesive tape. It is. l...Unvulcanized rubber sheet, 2...Adhesive tape. Figure 1 (a) (b) Procedural amendment January 80, 1980 1. Indication of the case 1988 Patent Application No. 280558 2. Name of the invention Rubber bonding method 3. Person making the amendment 1yI Section Patent Applicant (527) 1 person other than Brideston Tire Co., Ltd. 5゜1 Specification, page 2, line 13, "poor bonding" was changed to "poor adhesion" G
I will correct this. 2, page 3, lines 12-13 are corrected as follows. ``A large step was created between the inner liner and the cover tape.'' 3, page 3, lines 17-18, ``Complete adhesion was not removed'' was corrected to ``Complete adhesion was not removed.'' 4 On page 7, line 6, ``the part of the film that is the base material'' is corrected to ``the part of the film that is the base material''.

Claims (1)

[Scope of Claims] L In a rubber-to-rubber adhesion method in which bonding parts of rubbers mainly composed of halogenated butyl rubber are overlapped, a release agent is sprayed on the rubber surface, and then pressure-vulcanized, the release agent is sprayed. The storage modulus (G') of the above bonded part was previously measured at 50'C, 15 Hz, and 1% strain was 5X10.
1. A method for adhering rubber to each other, characterized in that the adhesive tape is coated with an adhesive tape composed of a film layer made of a substance whose main component is a thermoplastic polymer of dyne/cm2 or more, and an adhesive layer.