JPS5825338A - Rubber composition - Google Patents

Abstract

PURPOSE:To provide a rubber compsn. which has excellent processability and gives vulcanized rubber having excellent physical properties, by blending a blocked polyisocyanate contg. a polydiene chain and an active hydrogen group- contg. compd. with a solid rubber. CONSTITUTION:1-50pts.wt. mixture composed of a blocked polyisocyanate (B) contg. a polydiene chain, such as a blocked polyisocyanate is which the isocyanate groups of a reaction product between butadiene homopolymer and tolylene diisocyanate are masked with a blocking agent such as a phenol, and an active hydrogen group-contg. compd. (C) such as ethylene glycol, is blended with 100pts.wt. solid rubber (A) such as natural rubber or a styrene/butadiene rubber in such a proportion as to give an equivalent ratio of the isocyanate group in component B to the active hydrogen group in compnent C of 0.8-1.2, to obtain a rubber compsn. which has excellent processability and gives vulcanized rubber having excellent physical properties.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rubber composition, and more specifically, when a solid rubber is blended with a specific blocked polyisocyanate and a compound having active hydrogen, both processability and physical properties of the vulcanized rubber are improved. The present invention relates to providing an excellent rubber composition.

Conventionally, in the processing of solid rubber, process oil and various plasticizers have been added to improve processability. However, although these process oils and plasticizers are effective in improving processability, they exist as foreign substances in the resulting vulcanized rubber, causing deterioration in the physical properties of the vulcanized rubber.

Therefore, attempts have been made in recent years to improve this by adding low-molecular-weight oligomers such as butadiene and isoprene, but these efforts have not been able to achieve sufficient effects. It has also been proposed to add a liquid polybutadiene having a hydroxyl group at the end or a prepolymer obtained from this liquid polybutadiene and an excess of diisocyanate (Japanese Patent Publication No. 19333/1983, Japanese Patent Publication No. 269/1989).
Publication No. 76).

However, just adding the above-mentioned liquid polybutadiene does not give a satisfactory effect; on the other hand, prepolybutadiene obtained from liquid polybutadiene and diisocyanate! Although it is recognized that the use of - is effective in improving the physical properties of vulcanized rubber, it has the disadvantage that processability is significantly inferior due to the urethane reaction that occurs during rubber processing.

The present inventors have conducted extensive research in order to eliminate these drawbacks and develop a rubber composition that has excellent processability and vulcanized rubber physical properties. As a result, in solid rubber, blocked%
Products containing polyisocyanate and active hydrogen group-containing compounds are easy to process due to their low viscosity when processing cross-wires, etc. Moreover, blocks can be dissociated by heating or other processing after pouring into vulcanized rubber products. It was discovered that the reactivity of the polyisocyanate was increased, resulting in a vulcanized rubber product with excellent physical properties. The present invention was completed based on this knowledge.

That is, the present invention provides a rubber composition comprising (A) solid rubber K, (B) blocked polyisocyanate containing a polydiene chain, and (C) a compound containing active hydrogen 1.

The solid rubber that is the component (A) used in the present invention is a component that serves as a pace for the composition of the present invention, and various types may be used depending on the purpose of use. Specifically, natural rubber, styrene-butadiene rubber, butadiene rubber, acrylonitrile-butadiene rubber.

Examples include chloroprene rubber, isoprene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, and mixtures thereof.

Next, the blocked polyisocyanate containing a polydiene chain, which is the component (B) of the composition of the present invention, is an isocyanate of a polyinsyanate containing a polydiene chain (urethane prepolymer containing an incyanate group containing a polydiene chain in the molecular chain). The group K is the incyanate group! It has a structure in which a blocking agent for skinning is bonded. Here, the above-mentioned polydiene chain-containing polyisocyanate has a hydroxyl group, an amino group, an imino group, or a carboxyl group at the molecular end.

It is a urethane prepolymer obtained by reacting a liquid diene polymer having an active hydrogen group such as a mercapto group with an organic polyisocyanate compound.

The liquid diene polymer has a number average molecular weight of 50
Diene polymers having 0 to 25,000 carbon atoms and 4 to 12 carbon atoms, copolymers thereof, and furthermore, these diene monomers and 2 carbon atoms.
There are copolymers with ~22 α-olefinic addition polymerizable monomers. Furthermore, when an unsaturated carmenic acid such as maleic anhydride or a derivative thereof is added to these liquid diene polymers, it goes without saying that liquid diene polymers modified with K are included. Specifically, butadiene homopolymer, isoprene homopolymer, butadiene-styrene copolymer, butadiene-isoprene copolymer, butadiene-acrylonitrile copolymer,
Examples include phtadiene-2-ethylhexyl acrylate copolymer and butadiene-n-octadecyl acrylate copolymer i-. Among them, the viscosity is 2,
000 voids or less, more preferably 500 voids or less, and the chemical structure has 50% or more of 1,4 bonds (□ It is preferable to use a polymer.

On the other hand, organic polyisocyanate compounds that react with the liquid diene polymer include, for example, tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, polymethylene polyphenyl polyisocyanate, liquid modified diphenylmethane diisocyanate, xylylene diisocyanate, cyclohexane phenylene diisocyanate, Cyclohexyl diisocyanate, naphthalene-1,5-diisocyanate.

xylylene-2,2'-diisocyanate, isopropylbenzene-2,4-diisocyanate, addition reaction product of polypropylene glyco-enzyme and tolylene diisocyanate,
Examples include an addition reaction product of 1 mol of trimethylolpropane and 3 mol of tolylene diisocyanate.

In order to produce the above-mentioned polydiene chain-containing polyisocyanate, the above-mentioned liquid diene-based polymer and an organic polyisocyanate compound may be reacted, but the reaction conditions at this time are not particularly limited and may be changed as appropriate. . For example, under an inert gas flow such as dry nitrogen, the reaction temperature is 30~! The temperature may be set at OO° C. and the reaction time may be in the range of 10 minutes to 10 hours. Further, in the above reaction, active hydrogen group-containing compounds other than the above-mentioned liquid diene polymer can also be used in combination.

Component (B) of the present invention is the incyanate group K of the polydiene chain-containing polyisocyanate obtained by the above method.
, to which a blocking agent for masking the isocyanate group is bonded. Here, the blocking agents include phenols such as phenol, cresol, xylenol, and nonylphenol, alcohols such as methanol, ethanol, and impropatol, caprolactam, and butypropanol.
Examples include lactams such as Lacta-5, oximes such as acetoxime, methyl ethyl ketoxime, and Schiff-hexanoxime, other imides, and esters.

Furthermore, component (C) in the composition of the present invention is an active hydrogen group-containing compound, and specifically includes the above-mentioned liquid diene polymer having active hydrogen groups and other compounds and substances.

Here, the liquid diene polymer is as described above,
Other active hydrogen group-containing compounds include ethylene glycol; propylene glycol, 1,4-butanediol,
Glycerin.

Low-molecular polyols such as trimethylerpropane, 1,2,6-hexandriol, and pentaerythritol,
Ethylenediamine 4,4/-methylene-bis-2-
Chloroaniline 4, For example, bisphenol propylene oxy I' obtained by addition polymerizing an amine compound such as 47-methylene-bis-2-ethylaniline, or an alkylene oxide such as ethylene oxide or propylene oxide to a low-molecular polyol or amine compound. There are polyether polyols such as adducts.

In addition, ethylene glycol, propylene glycol, l
, polyhydric alcohols such as 4-butanediol and heptalic acid, maleic acid, malonic acid, and succinic acid.

A polyester polyol that is a condensation polymer with a polybasic acid such as adipic acid or terephthalic acid and has a hydroxyl group at the end.
λ, acrylic polyol, castor oil.

You can also use tall oil.

The above (A), (B) in the composition of the present invention,
The blending ratio of component (C) is not particularly limited and may be determined depending on various conditions, but usually components (B) and (C) are added to 100 parts by weight of solid rubber, which is component (A). A total of 1 to 50 parts by weight, preferably 2 to 30 parts by weight, and the ratio of components (B) and (C) to isocyanate groups in component (B) and active hydrogen groups in component (C). 0
, 8 to 1.2 (equivalent ratio).

In the composition of the present invention, the above (A), (B), (
Even if component C) is blended, since the incyanate group in component (B) is blocked, (A), (B), (
C) No reaction occurs between the components. Therefore, processability and stability are good when kneading these components. Moreover, (B) in the composition of the present invention,
Component (C), especially component (B), acts as a processing aid or plasticizer during processing, so that the processability becomes even better.

The composition of the present invention basically consists of the above (A), (B),
It consists of the three components (C), and if necessary, it may also contain iodine, a vulcanizing agent such as magnesium oxide, zinc oxide,
Vulcanization aids such as stearic acid, vulcanization accelerators such as mercaptobenzothiazole, dibenzothiazyl disulfide, N-cyclohexyl-2-benzothiazyl sulfinamide, plasticizers, processing aids such as process oil, or carbon. Appropriate amounts of fillers (reinforcing agents) such as black, white carbon, and pigments can also be added.

The composition of the present invention can be obtained by thoroughly kneading the above components (M), (B), and (C) and various additives as necessary, but the processing temperature at this time is usually It should be controlled to below 100°C. If the temperature is too high, the blocking agent will dissociate from the blocked isocyanate groups in component (B), so there is a risk that the vulcanization reaction will proceed during cross-contact. sometimes unresponsive,
In addition, since the component (B) acts as a processing aid, plasticizer, etc., the viscosity is relatively low and the processability is very good even without adding other processing aids. Moreover, it is stable because it does not react, and the storage stability of unvulcanized rubber is excellent.

Furthermore, if the composition of the present invention is heated to 100°C or higher, preferably about 120 to 160°C after being processed into a product, the blocking agent in the above-mentioned component (B) will dissociate and the reaction will be inhibited. It progresses quickly and becomes a vulcanized rubber product.
Mechanical strength, wear resistance.

It has significantly superior physical properties such as oil resistance.

At this time, component (B) has an activated inocyanate group,
It reacts with the active hydrogen group-containing compound which is component (C) and other additives, or with the solid rubber which is component (i), and greatly contributes to improving various physical properties of the product.

As mentioned above, the composition of the present invention is not only easy to process, but also provides excellent physical properties when vulcanized into a product. Therefore, the composition of the present invention can be effectively used in the production of various rubber products.

Next, the present invention will be explained in more detail with reference to Examples.

EXAMPLES AND COMPARATIVE EXAMPLES Compounding and kneading were carried out according to the following rubber compounding preparation specifications using the compounding ratios shown in No. 11KK. The blending of the blocked polyisocyanate, component (B), was the same as the blending of the process oil.

NR (Natural Rubber) ------- ASTM
D3184SBR (styrene-butadiene rubber) -
1---JTS K63g3BB (butadiene rubber) +++++++-+++ A8TM D3189N
BB (acrylonitrile-butadiene rubber)--JIS
K6388th R (chlorprene rubber) -++++
--+- JI8 K6388 Next, the unvulcanized rubber physical properties of the obtained composition were measured in accordance with the unvulcanized rubber physical test method of JI8 K6300. Furthermore, it is cured by vulcanization to produce a vulcanized rubber product, and its normal physical properties are determined according to JIS K63.
Measured according to 01K. The vulcanization time was determined by measuring the 90-cure time.

Mine 1 Natural rubber R88su 3 Rice 3 Ptaj xy com (N1pol BR1220
, Nippon Theon (a) II)-1Il-5 chloroprene rubber (WX-J, manufactured by Showa Neoprene Co., Ltd.) Rice 6 Mercaptobenzothiazole rice 8 Dipenzothiadyl disulfide rice 9 Tet 2-methylthiclam disulfide 410 2 -Mercaptoimidacillin rice 11 Diana process oil MS-24 (manufactured by Idemitsu Kosan Co., Ltd.) rice 12 Dioctyl phthalate rice Is *Phenol polymer of prepolymer of 14 *16 CR only 150"c, others 145°C Procedural amendment w (spontaneous) September 9, 1980 Patent application for the award of the case to Mr. Haruki Shimada, Commissioner of the Patent Office, 1984-124025 2. Name of the invention Rubber composition 5. Relationship with the ministry case for amendment Patent applicant Idemitsu Kosan Co., Ltd., Agent Address: 1-5 Nihonbashi Honmachi, Chuo-ku, Tokyo 103 Detailed explanation of the invention in the specification subject to amendment - Urijosho Page 15, Table 1, left column, bottom line and page 14 of the same,
Table 1 (Continued) In the bottom row of the left column, in the normal state physical properties, correct [tear strength (kg, t/cs)] (total of 2 places) to [tear strength (kg, t/ls) J.

Claims (1)

[Scope of Claims] (xr, (A) Solid rubber, (B) blocked polyisocyanate containing a polydiene chain, and (C) active hydrogen group-containing compound. +21, (A) Solid 100 parts by weight of rubber, (B) polydiene chain-containing blocked polyinocyanate and (
C) The total amount of active hydrogen group-containing compounds is 1 to 50 parts by weight, and the isocyanate group/active hydrogen group ratio is 0.8 to 1.2.
(fi amount ratio) Claim 1
The rubber composition described in .