JPS6253354A - Reactive plasticizer for rubber and composition containing same - Google Patents

Abstract

PURPOSE:To provide a reactive plasticizer for rubber, composed of a specific polysulfide, free from the bleeding out to the surface of a rubber and scarcely extractable with a solvent when compounded to a rubber composition and vulcanized. CONSTITUTION:The objective reactive plasticizer for rubber is composed of a polysulfide of formula (R is 2-4C alkylene, preferably ethylene, propylene or 1,4-butylene; m is 1-8, preferably 1-4; n is 2-370, preferably 7-150) having a molecular weight of 1,500-50,000, preferably 2,000-20,000. The compound can be produced by condensing a dichloroalkylformal with sodium polysulfide and, if necessary, controlling the molecular weight of the produced polymer. 100pts.(wt.) of a polymer vulcanizable with sulfur and selected from natural rubber, SBR, BR, IR, IIR, NBR, CR and EPDM is compounded with 0.1-10pts. of a vulcanizing agent composed mainly of sulfur and 5-50pts. of the present reactive plasticizer.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to reactive plasticizers and compositions for rubber.

[Conventional technology]

Conventionally, as reactive plasticizers and compositions for rubber, rubber compositions containing polyene polyols having polybutadiene, polyisoprene, etc. in the main chain and ethylene oxide adducts thereof have been known. (For example, JP-A No. 56-81846) [Problems to be solved by the invention] However, the plasticizer bleeds out on the surface of the rubber vulcanized with the above composition, and the surface becomes sticky, and the rubber is vulcanized by the solvent. There was a problem with being extracted.

[Means for solving problems]

The present inventors have arrived at the present invention as a result of studying reactive plasticizers for rubber that do not bleed out onto the rubber surface and are hardly extracted by solvents, and compositions containing the same. %Formula%(1) In the C formula, R is a C2-C4 alkylene group, m is 1-8, n
is 2-370. ) A reactive plasticizer for rubber characterized by consisting of a polysulfide (first invention) and (1) a reactive plasticizer with the general formula % formula % (1
) In formula C, R is a C2-C4 alkylene group, m is 1-8, and n is 2-370. ) polysulfide, (
A rubber composition (second invention) characterized by comprising 2) a polymer having rubber elasticity and (3) a vulcanizing agent.

In general formula (1), examples of the alkylene group R include ethylene, propylene, trimethylene, butylene group (
1,2-; 1. a-; 2,8-; 1,4-butylene) and two or more groups thereof. Among these, ethylene and propylene are preferred.

1.4-butylene group.

m is usually 1-8, preferably 1-4.

n is usually 2 to 370, preferably 7 to 150, particularly preferably 7 to 74.

The molecular weight (average molecular weight) of the polysulfide represented by general formula (1) is usually 1,500 to 50,000, preferably 2.000 to 20,000, particularly preferably 2.
000 to 10,000. If the molecular weight is less than 1,500, it has poor compatibility with rubber and may cause bleed-out.
If it exceeds .000, the viscosity increases and workability deteriorates, and the plasticizing effect decreases by 4f/. The viscosity (40° C., voids) is usually 5 to 7,000, preferably 15 to a, o o o.

Polysulfide represented by general formula (1) can be produced by a known method (for example, the method of US Pat. No. 2,466,963). That is, after a polymer is produced by condensation of dichloroalkyl formal and sodium polysulfide, a polymer having a desired molecular weight can be obtained by depolymerizing with sodium bisulfide and sodium sulfite, if necessary.

In the present invention, examples of polymers having rubber elasticity (hereinafter abbreviated as polymers) include natural rubber, styrene-butadiene copolymer rubber (SBR), and polybutadiene rubber (BR).
, polyisoprene rubber (IR), butyl rubber (IIR)
), Act) Lonitrile-butadiene copolymerization-rm (
Examples include sulfur-curable polymers such as NBR), chloroprene rubber (CR), and ethylene-propylene-diene ternary copolymer rubber (EPDM).

Sulfur is mainly used as a vulcanizing agent, and examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur,
Insoluble sulfur etc. are used.

The amount of vulcanizing agent blended is usually 100 parts by weight of the polymer.
0.1''-10 parts by weight (hereinafter referred to as o, i-10 PHR), preferably 0.3-4 PHR.

The amount of the reactive plasticizer of the present invention added to the rubber is usually 5 to 50.
PHR, preferably 5-20 PHR. If the added amount is less than 5 PHR, there will be no plasticizing effect, and if it exceeds 50 PHR, the compatibility with rubber will deteriorate.

Compounding agents that may be added to the rubber composition of the present invention along with a vulcanizing agent and a reactive plasticizer include vulcanization accelerators (thiazole-based, guanidine-based, thiuram-based, etc.), metal oxides such as zinc white, Fatty acids such as stearic acid, anti-aging agents (aromatic amines, phenols, hydroquinones, quinolines, etc.) and reinforcing photonic agents (silicic acid and silicate compounds such as carbon black and white carbon, magnesium carbonate, calcium carbonate) , high styrene resin, etc.).

The reactive plasticizers of the present invention may be used alone or in combination with other plasticizers such as process oils and dioctyl phthalate (DOP). Other plasticizers are usually added in an amount of 5 to 30% with respect to the present reactive plasticizer.

As a method for producing the rubber composition of the present invention, a raw material polymer is mixed with a two-roll or Banbury mixer, and a reactive plasticizer, a vulcanizing agent, and other compounding agents are kneaded to obtain a compounded rubber.

Then, the obtained compounded rubber is subjected to normal conditions, e.g.
170°C, 10 minutes to 1 hour, 2 to 100 kgACrn
A rubber composition is obtained by vulcanization under the conditions of 2 pressurization.

〔Example〕

The present invention will be further explained below with reference to Examples, and the reactive plasticizers of the present invention are shown in Table 1.

Table 1 Comparative Examples 1 to 4 Poly bd R-45HT (hydroxyl group content 0.83
meq/! Polybutadiene glycol (manufactured by Idemitsu Petrochemical Co., Ltd.) having an average molecular i of 2,800 was added with 20 moles of ethylene oxide by a conventional method, and the average molecular weight (CGPC method) of this product was 3,700. This was used as the reactive plasticizer of Comparative Example 1. Also commercially available reactive plasticizers r)
olybd R-45HT in Comparative Example 2, two commercially available plasticizers, namely Diana Process Oil AH-24 [manufactured by Idemitsu Kosan ■] in Comparative Example 3, and Diana Process Oil N5
Comparative Example 4 was obtained.

Examples 8 to 10 and Comparative Examples 5 to 8 Using two rolls, reactive plasticizer (Example 1゜2.4)
and comparative products (Comparative Examples 1 to 3), various rubber compositions were prepared based on the following formulations.

(Rubber compounding prescription) NBR (N1pol 1042. Manufactured by Nippon Zeon Co., Ltd.)
100 parts carbon black ()IAF)
50 zinc white 5.
0 Stearic acid 1.0 Antioxidant (PBN) 1.0 Vulcanization accelerator (MBTS) 1.5 (TM
T) 0.15 sulfur
1.5 plasticizer
Separate Note (Table 2) -+IPBN: Phenyl-β-naphthylamine Vulcanization was performed for minutes at a pressure of 10 kti/crn2 to prepare a specified test piece.

Using the test piece, Mooney viscosity (MLI + 4100°
C) is JISK6800 hardness (JISA 25°C) and tensile stress, Mloo and M2O3 (kg f/arr
2) is JIS K6aO1, plasticizer extraction rate -1 (%, acetone, 8 hours), plasticizer extraction rate -2 (% benzene 20
The rubber properties were tested in accordance with JIS K6350. Further, after vulcanization, the rubber surface was left to stand at 25°C for 3 days, and bleed-out on the rubber surface was visually determined. The results are shown in Table 2. Table 2: No nib bleed out, Δ: Slight bleed out, × With nib bleed out Examples 11-13 and Comparative Examples 9-12 Examples 8-10 and Comparative Examples 5- Similarly to Example 8, various rubber compositions were prepared based on the following formulations and their rubber properties were evaluated. The results are shown in Table 3.

(Rubber compounding formula) SBR (#1500) 100 parts Carbon black (HAF) 50 Zinc white 3.0 Stearic acid 1.0 Anti-aging agent (8C) 1
．． ．． 0 Vulcanization accelerator (DZ”) 1.0 Sulfur 1.8 Plasticizer
Appendix 4 Table 3) Rice 5 3C; N-isopropyl-N-phenyl-p-phenylenediamine + 6DZ; N,N-dicyclohexyl-2-benzothiazylsulfenamide Table 3 Examples 14 to 16 and Comparative Example 13 ~16 Examples 8-1
In the same manner as in Example No. 0 and Comparative Examples 5 to 8, various rubber compositions were prepared based on the following formulations, and the rubber properties were evaluated. The results are shown in Table 4.

(Rubber compounding prescription) Natural rubber (R5S #8) to
Part o Calcium carbonate 60 White carbon 20 Zinc white
3.0 stearic acid
1.0 Anti-aging agent (PA”)
1.0 Vulcanization accelerator (MBTS)
1.5 sulfur l
・8 plasticizer separate note (Table 4) + 7P
A: Phenyl-α-naphthylamine [Effects of the Invention] The vulcanized product of the rubber composition blended with the reactive plasticizer of the present invention does not bleed out and is hardly extracted by solvents.

That is, conventional polyene polyols and reactive plasticizers, which are alkylene oxide adducts thereof, have poor compatibility with rubber, causing bleed-out and being extracted into solvents at a considerable rate. However, this reactive plasticizer does not bleed out and the surface does not become sticky, even though all of its components are polyether except for sulfur.

Small or 4-reactive plasticizers are much less extracted into solvents than the reactive plasticizers that are conventional polyene polyols and their alkylene oxide adducts. Therefore, even if the rubber is immersed in a solvent for a long time, the plasticizing effect will not deteriorate and the plasticizer will not be lost by heating. Also, when used in combination with other types of rubber, the plasticizer will not migrate to the other type of rubber.

Furthermore, as seen in the reduction in Mooney viscosity, the viscosity of unvulcanized rubber can be lowered to improve processing workability.

Because of the above effects, the present reactive plasticizer is extremely useful as a plasticizer for rubber products such as tire hoses, belts, packing, rubber molded products, civil engineering and construction rubber materials, and footwear.

Claims (1)

[Claims] 1. General formula HS-(ROCH_2ORS_m)-_n_-_1RO
CH_2ORSH (1) (In the formula, R is a C_2 to C_4 alkylene group, m is 1 to 8
, n is 2-370. ) A reactive plasticizer for rubber, characterized by consisting of polysulfide represented by: 2. The molecular weight of polysulfide is 1500-50,00
0. The plasticizer according to claim 1, wherein the plasticizer is 0. 3. (1) General formula HS-(ROCH_2ORS_m)-_n_-_1RO as a reactive plasticizer
CH_2ORSH (1) (In the formula, R is an alkylene group of C_2 to C_4 m is 1 to 8,
n is 2-370. ), (2) a polymer having rubber elasticity, and (3) a vulcanizing agent. 4. The polymer is natural rubber, styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), polyisoprene rubber (IR), butyl rubber (IIR), acrylonitrile-butadiene copolymer rubber (NBR), chloroprene rubber ( 4. The composition of claim 3, wherein the composition is a sulfur vulcanizable polymer selected from the group consisting of ethylene-propylene-diene terpolymer rubber (EPDM) and ethylene-propylene-diene terpolymer rubber (EPDM). 5. The composition according to claim 3 or 4, wherein the vulcanizing agent is sulfur. 6. The amount of vulcanizing agent is 0.1 to 100 parts by weight of the polymer.
10 parts by weight of a composition according to any one of claims 3 to 5. 7. The amount of reactive plasticizer is 5 parts by weight per 100 parts by weight of the polymer.
A composition according to any one of claims 3 to 6, wherein the composition is 50 parts by weight.