JPH11269311A - Rubber complex composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber complex composition designed to lighten the composition and having improved fatigue resistance against a large repeated extending deformation by dispersing microballoons obtained by heat expansion of microcapsules in a state having remained partitions, in a rubber. SOLUTION: This rubber complex composition is the one obtained by adding microcapsules, sulfur, a vulcanization accelerator or the like to a rubber. The composition is obtained by adding a paste material obtained by mixing at least one kind of microcapsule having 120-140 deg.C expansion-starting temperature and 180-220 deg.C expansion maximum temperature, involving isobutane and/or isopentane in a partition material, and having a polyacrylonitrile- methacrylonitrile copolymer and/or a polyacrylonitrile-methacrylonitrile-methyl methacrylate copolymer as the partition material, with a titanate coupling agent regulated so that the amount of the titanate coupling agent may be 0.5-5 times as much as the amount of the added microcapsule.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composite composition, and more particularly, to a rubber composite in which microcapsules are dispersed as microballoons in rubber to reduce weight and improve fatigue resistance against large repeated stretching deformation. Composition.

[0002]

2. Description of the Related Art Sponge is well known as a lightweight and flexible composition. However, the sponge stretched,
Not only are the strength, modulus, hardness, and tear strength all small, but they also have drawbacks such as inability to be used for high-performance applications due to large variations in their physical properties, and poor water shielding.

[0003] As another lightweight rubber improved in such a point, a rubber containing an inorganic hollow powder such as glass or ceramics in the rubber is known. Furthermore, recently, rubber materials containing organic microcapsules such as phenolic resin, polyamide resin, polyurethane resin, methyl methacrylate, vinylidene chloride resin, polyacrylonitrile, polyvinylidene chloride / acrylonitrile copolymer, etc. Are known.
-53567 and JP-A-4-246440.

[0004]

However, conventional inorganic microcapsules do not contribute significantly to weight reduction because of their large specific gravity. On the other hand, organic microcapsules may lack heat resistance, and when the rubber in which the microcapsules are dispersed is vulcanized at 140 to 160 ° C., the partition walls of the microcapsules are thermally expanded and broken, and vulcanized. The rubber becomes a foam and may be broken mechanically when the microcapsules are kneaded with the rubber, making it difficult to produce a composite in which the microballoons are dispersed in the rubber without breaking. . In addition, the conventional rubber in which microcapsules are dispersed has a problem that cracks are generated early when subjected to large repeated stretching deformation.

In consideration of these points, the present invention disperses microballoons in which microcapsules are thermally expanded in a state in which partition walls are left, in rubber to reduce the weight and to cope with large repeated deformation. To provide a rubber composite composition having improved fatigue resistance.

[0006]

That is, the invention according to claim 1 of the present application provides a rubber composite composition obtained by adding microcapsules, sulfur, a vulcanization accelerator and the like to a rubber, wherein the expansion start temperature is 120 to 140. ° C and maximum expansion temperature 180 ~ 2
20 ° C., at least one of isobutane and / or isopentane contained in the partition wall material, and polyacrylonitrile / methacrylonitrile copolymer or / and polyacrylonitrile / methacrylonitrile / methyl methacrylate copolymer as the partition wall material
A rubber composite composition in which a paste obtained by mixing a kind of microcapsules and a titanium coupling agent so that the amount of the titanium coupling agent is 0.5 to 5 times the amount of the microcapsules is added to the rubber. Yes, by bonding the microcapsules with a titanium coupling agent, the adhesion between the microballoons and the rubber can be improved, and the weight can be reduced and the fatigue resistance against large repeated stretching deformation can be improved. .

According to the invention of claim 2 of the present application, the amount of the microcapsules is 0.2 to 20 parts by weight based on 100 parts by weight of rubber.
In the rubber composite composition which is part by weight.

The invention according to claim 3 of the present invention relates to a rubber composite composition obtained by adding microcapsules, sulfur, a vulcanization accelerator and the like to rubber, wherein (a) 100 parts by weight of rubber
(B) The expansion start temperature is 120 to 140 ° C. and the maximum expansion temperature is 180 to 220 ° C., isobutane and / or isopentane are included in the partition wall material, and polyacrylonitrile / methacrylonitrile is used as the partition wall material. 0.2 to 20 parts by weight of at least one microcapsule having a coalesced or / and polyacrylonitrile / methacrylonitrile / methyl methacrylate copolymer and 0.2 to 20 parts by weight of titanium coupling agent; In the rubber composite composition added with 100 parts by weight, it is possible to reduce the weight as well as to improve the fatigue resistance against large repeated elongational deformation as in the first aspect of the invention.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The rubber used in the present invention includes:
Natural rubber, polyisoprene rubber, polybutadiene rubber,
Ethylene-α- such as styrene-butadiene copolymer rubber, chloroprene rubber, ethylene-propylene rubber
Olefin copolymer rubber, nitrile rubber (NBR),
Hydrogenated nitrile rubber (H-NBR) to which an unsaturated carboxylic acid metal salt is added, alkylated chlorosulfonated polyethylene (ACSM), chlorosulfonated polyethylene rubber (CSM) or the like as a main component. Such reinforcing agents, fillers, softeners, antioxidants, vulcanization aids, and vulcanizing agents such as sulfur are added and mixed.

The microcapsules used in the present invention include those in which isobutane and / or isopentane are contained in a partition wall material made of polyacrylonitrile / methacrylonitrile copolymer, and polyacrylonitrile / methacrylonitrile / methyl methacrylate copolymer. Isobuta and / or isopentane encapsulated in a partition material made of coalesced material, or in a partition material made of polyacrylonitrile / methacrylonitrile copolymer and polyacrylonitrile / methacrylonitrile / methyl methacrylate copolymer Some include isobutane and / or isopentane, and one or more of these can be used. The partition wall material of the microcapsule is excellent in heat resistance as compared with conventional polyamide resin, polyurethane resin, methyl methacrylate, vinylidene chloride resin, polyacrylonitrile, polyvinylidene chloride / acrylonitrile copolymer and the like.

The microcapsules must have an expansion start temperature of 120 to 140 ° C. since they must not thermally expand at such temperatures during kneading and rolling before vulcanization.
In addition, since the capsules expanded during vulcanization do not break, the maximum expansion temperature is higher than the vulcanization temperature and is 180 to 220 ° C. That is, the microcapsules are sufficiently thermally expanded in the vulcanization induction time region in which the Mooney viscosity before vulcanization has decreased,
When fully expanded, the rubber needs to be vulcanized. This microcapsule has about 64 times its original size in volume.
Thermal expansion up to double. The vulcanization induction time for thermal expansion of the microcapsules is 1 to 10 at a temperature of 140 to 200 ° C.
Minutes. As a guide for the most preferable conditions, 150 °
It is necessary to design the rubber compound such that the vulcanization induction time at C is 4-7 minutes.

The amount of microcapsules added is 100
It is added in an amount of 0.2 to 20 parts by weight, preferably 0.5 to 5 parts by weight based on parts by weight. If it exceeds 20 parts by weight,
Mechanical strength such as tensile strength and elongation is undesirably reduced, and if less than 0.2 parts by weight, the purpose of reducing the weight of the rubber composite cannot be achieved.

However, in the present invention, it is necessary to subject the microcapsules to a surface treatment with a titanium coupling agent. Specifically, the microcapsules and the titanium coupling agent are mixed, and a paste is added to the rubber. In this case, the added amount of the titanium coupling agent / the added amount of the microcapsules is 0.5 to 5. When the amount is less than 0.5, the fatigue resistance is deteriorated. Occur.

In the present invention, it is not necessary to pre-treat the surface of the microcapsules with a titanium coupling agent.
0 parts by weight can be added. When the addition amount of the titanium coupling agent is less than 0.1 part by weight, the effect of improving the adhesion is small. On the other hand, when it exceeds 100 parts by weight, the hardness of the composite rubber composition itself increases and the composite rubber composition becomes brittle, and on the contrary, fatigue Worse.

As the titanium coupling agent used here, for example, isopropyl triisostearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl (N-aminoethyl-
Aminoethyl) titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate, bis (dioctylpyrophosphate) oxyacetate titanate, bis (dioctylpyrophosphate) ethylene titanate, isopropyldimethacryliso And stearoyl titanate.

In the present invention, short fibers may be used as a reinforcing material. As the short fibers, polyester, polyamide, aramid, vinylon, organic fibers such as cotton are used,
Its length is 2 to 10 mm, and the amount added is 10 rubber.
It is 2 to 30 parts by weight with respect to 0 parts by weight. If the addition amount is less than 2 parts by weight, there is no reinforcing effect, and if it exceeds 30 parts by weight, short fibers are entangled with each other and thermal expansion of the microcapsules is prevented.

Further, in the present invention, sulfur, a vulcanization retarder, a vulcanization accelerator, a puffing agent, a reinforcing material, and the like can be added. The addition amount of sulfur is 1 to 60 with respect to 100 parts by weight of rubber.
It is part by weight, and it is necessary to increase the addition amount of sulfur when highly crosslinking is performed.

The vulcanization retarder used here prevents the rapid increase in viscosity that occurs with the start of vulcanization and helps the microcapsules to expand. Specifically, phthalic anhydride, benzoic acid and salicylic acid Examples include organic acids, nitroso compounds such as N-nitrosophenylamine, N-cyclohexylthiophthalimide, and phosphoric triamides. The amount of the vulcanization retarder to be added is 1 to 6 parts by weight based on 100 parts by weight of rubber. If the amount is less than 1 part by weight, the thermal expansion of the microcapsules is insufficient and the vulcanization of the rubber composite composition is performed. Good products cannot be obtained due to severe irregularities on the surface of the product. On the other hand, if it exceeds 6 parts by weight, the vulcanization induction time during which the Mooney viscosity decreases will be too long, and the vulcanization reaction will be inhibited.

Examples of the vulcanization accelerator include N-cyclohexylbenzothiazylsulfenamide, N, N-diethyl.
2-benzothiazylsulfenamide, 2-mercaptobenzothiazole, 2-mercaptothiazoline, 2-mercaptoimidazoline, diphenyl guanidine, triphenyl guanidine, thiohydropyridine, Zn-
Dimethyl dithiocarbamate, Zn-diethyl dithiocarbamate, Zn-diethyl dithiocarbamate, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, other aldehydes
There are ammonia, aldehyde / amines, alkyl / amines, nitrosos and the like, and there is no particular limitation. The added amount is 1 to 5 parts by weight based on 100 parts by weight of rubber, and if it is less than 1 part by weight, a good vulcanizate of the rubber composite composition cannot be obtained. On the other hand, if it exceeds 5 parts by weight, the vulcanization rate is too slow to hinder the thermal expansion of the microcapsules and the surface of the vulcanizate has severe irregularities, so that a good product cannot be obtained.

The peptizer reduces the Mooney viscosity at the time of vulcanization to efficiently perform the thermal expansion of the microcapsules. In particular, when the rubber is kneaded with a Banbury mixer, the molecular chains are appropriately cut, Mooney viscosity can be reduced. Specific examples thereof include di-ortho-benzamidophenyl disulfide, pentachlorothiophenol, dixylyl disulfide, sulfonated petronium, and zinc salt of pentachlorothiophenol.

The addition amount is 0.5 to 4 parts by weight with respect to 100 parts by weight of rubber. If the addition amount is less than 0.5 part by weight, the microcapsules do not expand sufficiently due to insufficient decrease in viscosity. On the other hand, the surface of the vulcanizate of the rubber composite composition has severe irregularities, and a good product cannot be obtained. On the other hand, if the amount exceeds 4 parts by weight, the residual peptizer breaks the molecular chains during vulcanization, thereby lowering the vulcanization properties.

In the present invention, short fibers may be used as a reinforcing material. As the short fibers, polyester, polyamide, aramid, vinylon, organic fibers such as cotton are used,
Its length is 2 to 10 mm, and the amount added is 10 rubber.
It is 2 to 30 parts by weight with respect to 0 parts by weight. If the addition amount is less than 2 parts by weight, there is no reinforcing effect, and if it exceeds 30 parts by weight, short fibers are entangled with each other and thermal expansion of the microcapsules is prevented.

As a method for obtaining the rubber composite composition of the present invention, there are a method of masticating rubber with a roll and a method of masticating with a Banbury mixer. When masticating with a roll, after kneading the rubber with a roll, microcapsules with a masticated rubber, a vulcanization retarder, magnesium oxide, other fillers, softeners, An antioxidant and the like are added, and then sulfur and a vulcanization accelerator are kneaded to obtain a rubber composition.

On the other hand, in the case of mastication with a Banbury mixer, rubber and a shaking agent are masticated with a Banbury mixer, and then microcapsules, a vulcanization retarder, magnesium oxide and, if necessary, are added. Other fillers, softeners, antioxidants, etc. are added and kneaded,
Thereafter, sulfur and a vulcanization accelerator are added to obtain a rubber composition. The rubber composition thus obtained is formed into a sheet using a roll such as a calender roll, and then vulcanized. As the vulcanizing device, mold heating, hot air heating, a rotary drum type vulcanizing machine, an injection molding machine and the like can be used.
In addition, as a kneading method, a roll, a kneader, an extruder, or the like can be used in addition to the Banbury mixer.

[0025]

The present invention will be described in more detail with reference to the following examples. Examples 1-4, Comparative Examples 1-3 After masticating natural rubber with a Banbury mixer,
Subsequently, MgO, stearic acid, microcapsules and an antioxidant are added and kneaded by the same Banbury mixer,
Subsequently, sulfur and a vulcanization accelerator were added to obtain a rubber compound.
Then, sulfur was added to the rubber compound by a roll maintained at a temperature of 70 to 90 ° C. to produce an unvulcanized rubber sheet having a predetermined thickness. The microcapsules used were those which had been surface-treated with a titanium coupling agent in advance, and when this surface treatment was not performed, a titanium coupling agent was added to the rubber.

The obtained unvulcanized rubber sheet was stored in a press machine adjusted to 150 ° C. for 20 minutes to obtain a 5 mm thick vulcanized rubber sheet expanded to a predetermined magnification. The thickness β of the unvulcanized rubber sheet is determined by the following formula. α (predetermined magnification) = {(100−X) + 64 ×} × 0.9
/ 100 β (predetermined thickness) = 5 ÷ α X = addition amount of microcapsule (% by weight)

The expanded 5 mm-thick vulcanized rubber sheet was sliced to about half the thickness, and its mechanical properties were determined in accordance with JIS K6301. The specific gravity was JIS K6300.
It was determined according to. In the fatigue test method, 0-400
%, And the number of cracks after 200 times was visually measured. Table 1 shows the results.

[0028]

[Table 1]

From these results, it can be seen that the rubber composite compositions of Examples have a small number of cracks after fatigue and are excellent in fatigue resistance. However, when the ratio of the added amount of the titanium coupling agent / microcapsule is out of the range of 0.5 to 5, the number of cracks is increased, the fatigue resistance is deteriorated, and insufficient expansion of the microcapsule occurs. ing.

[0030]

As described above, according to the first and second aspects of the present invention, the expansion start temperature is 120 to 140 ° C. and the maximum expansion temperature is 180 to 220 ° C., and isobutane or / and / or Then, isopentane is encapsulated, and at least one microcapsule having a polyacrylonitrile / methacrylonitrile copolymer or / and a polyacrylonitrile / methacrylonitrile / methyl methacrylate copolymer as the partition wall material and a titanium coupling agent, A rubber composite composition in which a paste mixed with a coupling agent in an amount of 0.5 to 5 times the amount of the microcapsules added to the rubber,
By bonding the microcapsules with a titanium coupling agent, the adhesive force between the microballoon and the rubber can be improved, the weight can be reduced, and the fatigue resistance against large repeated stretching deformation can be improved.

The invention according to claim 3 of the present application is characterized in that (a) rubber 1
(B) The expansion start temperature is from 120 to 1
40 ° C. and the maximum expansion temperature is 180 to 220 ° C., isobutane and / or isopentane are included in the partition wall material, and polyacrylonitrile ·
0.2 to 20 parts by weight of at least one microcapsule having a methacrylonitrile copolymer or / and a polyacrylonitrile / methacrylonitrile / methyl methacrylate copolymer and a titanium coupling agent,
And (c) a rubber composite composition to which 0.1 to 100 parts by weight of a titanium coupling agent is added. Can be improved.

Continuation of the front page (51) Int.Cl. ⁶ Identification code FI C08K 9:10 3:06 5:00)

Claims (3)

[Claims] 1. A rubber composite composition obtained by adding microcapsules, sulfur, a vulcanization accelerator and the like to rubber has an expansion start temperature of 120 to 140 ° C. and a maximum expansion temperature of 180.
At least 220 ° C., at least isobutylene or / and isopentane is contained in the partition wall material, and at least a polyacrylonitrile / methacrylonitrile copolymer or / and a polyacrylonitrile / methacrylonitrile / methyl methacrylate copolymer is contained as the partition wall material. A paste in which one kind of microcapsule and a titanium coupling agent are mixed so that the titanium coupling agent is 0.5 to 5 times the amount of the microcapsule added is added to the rubber. Rubber composite composition. 2. The amount of microcapsules added is 100 rubber.
The rubber composite composition according to claim 1, wherein the amount is 0.2 to 20 parts by weight based on parts by weight. 3. A rubber composite composition comprising a rubber and microcapsules, sulfur, a vulcanization accelerator, etc., wherein (a)
With respect to 100 parts by weight of rubber, (b) the expansion start temperature is 12
0-140 ° C and maximum expansion temperature 180-220 ° C
Wherein at least one type of microcapsule containing isobutane and / or isopentane in the partition material and having a polyacrylonitrile / methacrylonitrile copolymer or / and a polyacrylonitrile / methacrylonitrile / methyl methacrylate copolymer as the partition material. 0.2 to 20 parts by weight of capsule and titanium coupling agent, and (c) 0.1 to 1 part of titanium coupling agent
A rubber composite composition characterized by adding 00 parts by weight.