JPS61252237A - Method for partially curing surface of unvulcanized rubber member - Google Patents

Abstract

PURPOSE:To partially cure the surface of an unvulcanized rubber member at a low cost without adversely affecting the physical properties of the rubber, by applying a specified halide to the surface of an unvulcanized rubber member formed from a rubber compsn. contg. a monomaleimide. CONSTITUTION:A halide of formula II is applied to at least one surface of an unvulcanized rubber member formed from an unvulcanized rubber compsn. obtd. by blending 0.1-5.0pts.wt. monomaleimide of formula I with 100pts.wt. rubber selected from among natural and synthetic diene rubbers. In the formulas, R<1>, R<2> are each H, a 1-4C alkyl, others R<1> is HR<2> is phenyl; R<3> is H, methyl, Cl, Br; X is Cl, Br, the substituents are attached to the benzene ring at the ortho, meta or para position. An example of the monomaleimide is N-(p-N',N'- dimethylaminophenyl)maleimide. An example of the halide is alpha,alpha'-dibromo-p- xylene.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a method for partially curing the surface of an unvulcanized rubber member, in particular, a method for partially curing the surface of an unvulcanized rubber member, and particularly a method for partially curing the surface of an unvulcanized rubber member. The present invention relates to a novel method for partially curing the surface of an unvulcanized rubber member, which imparts tensile strength and elastic modulus (hereinafter referred to as green strength and green modulus, respectively) to unvulcanized rubber.

(Prior Art) Rubber articles, especially those used under harsh conditions such as tires, have six different performance requirements for their constituent elements. It is not uncommon for rubber members to be used.

For this reason, prior to vulcanization, each component in an unvulcanized state is bonded and molded, but at this time, it may be necessary to expand the unvulcanized rubber component while forming dust. Strength, green modulus, etc. are required.

Further, at the stage of vulcanizing a rubber article made of a plurality of rubber members, it has often been impossible to arrange the structural NICOM member according to a desired design due to the flow of rubber between adjacent rubber members.

In particular, in tires, during vulcanization, as the tire inner pressure increases due to the Prada, the inner liner rubber is subjected to tension and at the same time is strongly pressed against the carcass compound, and the inner liner rubber is pushed between the carcass petite cords. As a result, the ply coating rubber may separate from the cord, causing ply separation. In severe cases, the ply cord may be exposed from the inner liner rubber, causing failures such as tube punctures and ply separation. This reduced the effective thickness of the liner rubber, deteriorating its properties as an air barrier, and was also unfavorable in terms of appearance.

Conventionally, as a method to solve the above-mentioned intermediate point, a method of improving the green modulus etc. at the time of unvulcanization has been known. There is no known method for partial vulcanization using radiation such as electron beams, and a method for creating a relatively small network during unvulcanization is disclosed in Japanese Patent Publication No. 47-11895 and U.S. Patent No. 85.
62303, etc., and a method for improving green strength by increasing cohesive force was published in Japanese Patent Publication No. 45-827.
No. 07, Special Publication No. 13062, Special Publication No. 47-15
No. 702, Japanese Unexamined Patent Publication No. 16996/1973, Special Publication No. 47-
No. 25712, Japanese Patent Publication No. 10635, 1973, Japanese Patent Publication No. 1973
-78790, JP-A-49-78791, JP-A-5
0-67890, JP 51-45198, JP 48-102148, JP 51-28841, JP 58-287, JP 56-147810, JP 56- 147811 publications and Namiki National Patent No. 418
It is described in the specification of No. 1653, etc.

In addition, methods for improving green strength through ionic bonding are disclosed in Japanese Patent Application Laid-open Nos. 50-75685 and 60-7954.
No. 1, JP-A-52-1171942, JP-A-52-1
17841, JP-A-52-155652, Namiki German Patent No. 1570304, etc.

Furthermore, Special Publication No. 84-6588 and Special Publication No. 10/1973
990 publications and Dutch Patent No. 6807047
No. 4,020,115 and US Pat. No. 895
1936, a method for improving green strength by increasing the crystallinity of a polymer, US Pat. No. 8,868,844, JP-A-50-77448, JP-A-58-52589 , Special Public Interest Publication Showa 47-11815
No., Japanese Patent Publication No. 48-12071, and U.S. Patent No. 4
A method using polymer entanglement by adding a high molecular weight component as seen in Japanese Patent Publication No. 41-8782, Japanese Patent Publication No. 41-18270, and U.S. Patent No. 4179480, U.S. Pat. Patent No. 416
No. 828f1, U.S. Pat. No. 4,152,870, a method using block polymers, or a method using additives, such as Japanese Patent Publication No. 46-40415,
JP 48-3900, JP 48-102147, JP 51-109049, JP 47,3914
No. 7, JP-A-48-14786, JP-A-50-511
44, JP-A-54-7450, U.S. Pat. No. 8,988,076, etc., there are methods that are not described in the specification of U.S. Patent No. 8,988,076. However, methods that use radiation such as electron beams require a large investment in equipment, and methods that use ionic bonds either add a tertiary amine during polymerization or add a tertiary amine in advance. It has the disadvantage that it cannot be applied to natural rubber because it requires a method such as polymerizing the added monomer. In addition, methods of increasing the crystallinity of the polymer, adding polymer components, or using block polymers may improve the green strength, but the properties of the matrix will change significantly.
This results in an adverse effect on the physical properties of the rubber after vulcanization, making it impractical.

In addition, with methods other than those using radiation such as electron beams mentioned above, when green strength is improved, the viscosity of the unvulcanized state naturally increases, resulting in poor calender workability, extrusion workability, etc. This had the disadvantage that factory workability was significantly reduced.

Therefore, there has been no technology for imparting desired green strength, green modulus, etc. to unvulcanized rubber members during molding and vulcanization processes at low cost and without reducing factory workability.

(Problems to be Solved by the Invention) The present invention provides an unvulcanized rubber member surface that is low in cost, does not adversely affect rubber physical properties, and does not reduce factory workability, which has not been achieved in the past. The present invention seeks to solve the problem of providing a partial curing method for.

(Means for Solving the Problems) As a result of intensive studies to solve the above-mentioned problems, the present inventors found that a certain monomaleimide compound reacts with a diene rubber molecule and bonds to this n. It was confirmed that this compound reacts with certain halides at room temperature to form ionic bonds, and that surface treatment of unvulcanized rubber members utilizing these reactions would be suitable for the above purpose, and the present invention was developed. I have achieved this goal.

That is, the present invention provides at least one type of rubber selected from the group consisting of natural rubber and diene-based synthetic rubber.
．． For the Jti part, the general formula (wherein, in the case of R-H, both n represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; otherwise, R1 is a hydrogen atom, R'' is a phenyl group) ) at least one monomaleimide compound represented by 0.1
~5. At least one surface of an unvulcanized rubber member made of an unvulcanized rubber composition containing a certain amount of Oi is coated with a compound having the general formula (R in the formula is a hydrogen atom, a methyl group, a chlorine atom, or a bromine atom, X represents a chlorine atom or a bromine atom, and the position of the substituent is ortho, meta, or para. This is a method for partially curing the surface of an unvulcanized rubber member.

In the present invention, diene-based synthetic rubbers include synthetic coli isoprene rubber (IR), polybutadiene rubber, and styrene rubber.
These include butadiene rubber, ethylene-propylene terpolymer, butyl rubber, halogenated butyl rubber, acrylonitrile-butadiene rubber, and may be used alone or in a blend. Natural rubber may also be used alone or in blends with diene-based synthetic rubbers.

Examples of monomaleimide compounds used in the present invention include N-(p-N', N'-dimethylaminophenylcomaleimide (DMMI), N-(1)-N'
, N'-diethylaminophenyl)maleimide (DEM
I), N-(p-N', N'-dipropylamino 0
phenyl)maleimide (DPMI), N-(1)-N'
.

N'-diptylaminophenyl)maleimide (DBMI
), N-p-aminophenylmaleimide (AI'MX
), N-(1)-N'-anilinophenyl)maleimide (PAPMI), etc., and these may be used alone or in combination of two or more. Furthermore, when conducting the tests shown in Examples, monomaleimide compounds were used as commercially available products or synthesized according to known synthesis methods. The blending amount of the monomaleimide compound is 0.1 to 5.0 parts by weight. If it is less than 0.1 part by weight, there is no effect (if it exceeds 5.0 parts by weight, it not only loses its weight-increasing effect but also has a negative effect on various physical properties after vulcanization. When used in combination with an agent such as carbon black, the monomaleimide compound causes some kind of interaction with the carbon black and/or the carbon gel generated near the carbon black, improving the dispersion of the carbon black and, as a result, significantly improving heat generation properties. In the present invention, it is necessary to bond the monomaleimide compound to the polymer, and in this case, dibenzothiazyl disulfide, peroxide, azobisisobutyronitrile (IBN), etc. If a radical initiator is used in combination, the monomaleimide compound can be bonded to the polymer more efficiently.

In the present invention, a halide is coated on the surface of an unvulcanized rubber member containing the above-mentioned monomaleimide compound. Methods such as dissolving the solution in a solvent at an appropriate concentration and applying it to the rubber surface using a brush or roll, spraying or immersing it in a solution in which a halide is dissolved can be used, but the present invention Any other method is acceptable as long as it does not defeat the purpose.

In such a case, the optimum concentration of the halide solution varies depending on the coating method, but is preferably 1 to 50% by weight.

However, such concentrations are not particularly important;
For example, it depends on conditions such as the application method and the expected degree of partial curing, and even if the concentration is low, if the number of applications is increased,
The same effect as using a highly concentrated solution can be achieved.

Examples of halides include α,αl-dibromo p
-xylene (BPX), α, α'-dibromo m-xylene (BMX), α, α'-dibromo 〇-xylene (BOX), α, α'-dibromo p-diethylbenzene (BPEB), α, α, α ', α'-Tetrabromo-p-xylene (TBPX), α, α, αl
, αI-tetrabromo-m-xylene (TBMX),
α, α, α′, α′-tetrapro%-〇-xylene (T
BOX ), α, αI-dichloro-p-xylene (a
px ), α, α′-dichloro-m-xylene (OMX
), α,α′-dichloro-xylene (COX
), and these may be used alone or in combination of two or more. Note that the halides used in the examples of the present invention are commercially available products.

Furthermore, in the present invention, the above-mentioned monomaleimide compound and halide react at room temperature to form an ionic bond,
If necessary, heat treatment at a temperature of about 50 to 120 degrees Celsius not only shortens the standing time until hardening, but also reduces variations in the degree of partial hardening due to changes in season and temperature. It is possible.

In addition to the above-mentioned monomaleimide compounds, halides, and reinforcing fillers, the present invention also uses compounding agents commonly used in the rubber industry, such as softeners, anti-aging agents, vulcanization accelerators, vulcanization accelerators, and vulcanization promoters. A sulfur agent and the like can be blended into the rubber as needed within the usual blending amount.

(Examples) Next, the present invention will be described in more detail with reference to Examples, Reference Examples, and Comparative Examples.

Reference Example I Synthesis of N-(P-N', N'-dimethylaminophenyl)maleimide (DMMI) Equipped with a reflux condenser, a thermometer, and a stirrer with a mercury seal 2
1. To the fourth flask, 400 ml of acetone and p-N,
102.1 g of N-dimethylaminoaniline (0.75
A solution of anhydrous maleic acid 84,69 dissolved in acetone 250 was added dropwise at room temperature for about 2 hours to the resulting solution, and the mixture was further stirred at 50°C for 1 hour. Next, after cooling to room temperature, acetic anhydride 191
．． 89 (1,875 mol) and sodium acetate 1
8.59 (0,225m01) and again 50'
The reaction was completed by stirring at ~60°C for 5 hours. After cooling to room temperature, 60 Qst of water was added little by little to crystallize the target product C1, and after filtration and washing well on filter paper with water,
158.5° to 154.5 after drying with hot air for 48 hours at 0°C
N-(p-N', N'-dimethylaminophenyl)maleimide having a melting point of 186.2 °C (yield -84,
1%).

Reference Example 2 Synthesis of N-(P-N', N'-dibutylami/phenyl)maleimide (DBMI) Using p-N instead of P-N, N-dimethylaminoaniline
, 78
．． N-(p-N' with melting point between 5° and 76.1°C
.

N'-dibutylaminophenyl)maleimide 231g (
A yield of -77.0% was obtained.

Reference Example 8 N-(4-anilinophenyl)maleit) (PAPMI
) Synthesis of p -M, M-dimethylaminoanili/instead of d, p-
By performing the same operation as in Reference Example 1 except for using aminodiphenylamine 188 (0.75m01), 16
N-(4-7 elinophenyl)maleimide z199 having a melting point of 1 DEG -168 DEG C. (yield -83.0 t) was obtained.

Examples 1-9, Comparative Examples 1-2 80 parts by weight of natural comb, 201 L of synthetic polyimprene rubber
parts by weight, HAF carbon black 50] parts by weight, 2 parts by weight of stearin, 1 part by weight of dibenzothiazyl sulfide. 0.6Ji parts of N-(1,1-dimethylbutyl]-N'-phenyl-p-phenylenediamine and 1.5 parts by weight of the monomaleimide compound shown in Table 1 were mixed in a Banbury mixer to 4 parts by weight. After mixing for a minute, take out the mixed material from the mixer, cool it, add zinc oxide atfi part, N-oxydiethylene-2-benzothiazolesulfenamide 0.5
An unvulcanized rubber composition was prepared by blending 5 parts by weight and 5 parts by weight of sulfur.

A rubber sheet with a thickness of 4 mm was prepared from the obtained unvulcanized rubber composition. Next, the halides shown in Table 1 were dissolved in taloloform at a concentration of 50% by weight and applied to the upper and lower surfaces of the rubber sheet, and after being left for one day and night, JIS Kas
Green strength, green modulus, and green elongation at 25°C and 80°C were measured according to O1. Results first
Shown in the table.

As is clear from Table 1, the unvulcanized rubber sheet produced by the method of the present invention shown in the examples has green strength,
The green modulus has been improved, and from this,
It can be seen that the surface coated with halide is partially cured.

It has a tread part and sidewall part made of a commonly used rubber composition, a carcass and a belt made of steel cord, and a carcass ply count of 28 and 1501111.
A green tire was prepared using a rubber composition having the composition shown in Table 2 as an inner liner rubber for a R track/pass radial tire, and vulcanized by a conventional method. At this time, a sheet was used as the inner liner (thickness: 4 mm), which was coated with BPX on the surface adjacent to the carcass ply according to Example 1 and left to stand day and night. The thus produced green tire was vulcanized to produce a tire. After vulcanization, the area around the inner liner is
As shown in FIG. 1, the rubber 1 of the inner liner is inserted between the carcass ply cords 2. The inner liner gauge (indicated by gauge L in Figure 1) on the shoulder part of the vulcanized tire (the gauge is also thinner after vulcanization) was obtained by Unit Process Assembles, Inc. ( UNIT PROCE
Made by SS ASSEMBLIESIN (! , )/・
Destructive Coating Thick *X ・f
X TA(N0N-DES1'RUOTIV 0OAT
INGTH WORK 0KNESS TESTKR) Derm
Measurements were taken at four locations around the itron D-9 Niyori tire. Furthermore, as a comparative example, a tire to which no halide was applied was also evaluated in the same manner. The results are shown in Table 8.

11g20Q *1 1
0HAF carbon black
5ON-(1,13--,'methylbutyl)-
N/-phenyl-p-phenylene%/7min 1 aroma oil 2
Zinc white 8 cobalt thethenate
8*1 Polyisoprene rubber manufactured by Japan Synthetic Rubber Co., Ltd. Table 8 *l Or average value, V7 indicates the drift difference value.

As is clear from Table 8, in the method according to the present invention, the inner liner gauge after vulcanization has a thickness more than 8 times that of the comparative example, and the variation in the thickness is also reduced, and the thickness of the inner liner gauge after vulcanization is reduced. It can be seen that the flow into the ply coating rubber is significantly improved.

(Effects of the Invention) As described above, the present invention enables processes such as molding and vulcanization of rubber articles by applying a specific halide to the surface of an unvulcanized rubber member containing a specific monomaleimide compound. It has the advantage that it can provide the unvulcanized rubber member with the necessary green strength and modulus in the process, and has no adverse effect on rolling or extrusion workability.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the arrangement relationship between the tire inner liner and the rubber cable cord.

Claims (1)

[Claims] 1. General formula ▲ Numerical formula, chemical formula, table, etc.▼ (formula In the case of R^1-R^2, both represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; otherwise, R^1 represents a hydrogen atom and R^2 represents a phenyl group. ) at least one monomaleimide compound represented by 0.1
At least one surface of an unvulcanized rubber member made of an unvulcanized rubber composition containing ~5.0 parts by weight has a general formula ▲a mathematical formula, a chemical formula, a table, etc.▼ (R in the formula ^3 represents a hydrogen atom, methyl group, chlorine atom, or bromine atom; 1. A method for partially curing the surface of an unvulcanized rubber member, comprising partially curing the vicinity of the surface by applying a compound. 2. The monomaleimide compound is N-(p-N', N'-dimethylaminophenyl)maleimide, N-(p-N',
N'-diethylaminophenyl)maleimide, N-(p
-N',N'-dipropylaminophenyl)maleimide, N-(p-N',N'-dibutylaminophenyl)maleimide, N-p-aminophenylmaleimide or N-
The method according to claim 1, which is (p-N'-anilinophenyl)maleimide. 3. The halides are α,α′-dibromo-p-xylene, α,α′-dibromo-m-xylene, α,α′-dibromo-o-xylene, α,α′-dibromo-p-diethylbenzene, α , α, α′, α′-tetrabromo-p-
Xylene, α, α, α′, α′-tetrabromo-m-xylene, α, α, α, α,-tetrabromo-o-xylene, α, α′-dichloro-p-xylene, α, α′-dichlor -m-xylene or α,α'-dichloro-o-xylene.