JP2003082221A - Rubber composition - Google Patents

Abstract

(57) [Summary] [PROBLEMS] For rubber, which is hardly extracted even when it comes into contact with oily substances, hardly volatilizes even at high temperatures, can improve the cold resistance of rubber, and has excellent workability in winter. Provide a plasticizer and a rubber composition. SOLUTION: The number average molecular weight 200 represented by the formula (I)
A rubber plasticizer comprising an ester of a glycol of up to 5000 and a branched fatty acid having 6 to 16 carbon atoms, and a rubber composition containing 3 to 50 parts by weight of the rubber plasticizer with respect to 100 parts by weight of rubber. Embedded image Wherein X is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms,
a is a number from 0 to 2, m and n are n / (m + n) = 0.0
The number which becomes 3-0.5 is shown. However, when a is 2, X is not a hydrogen atom. ]

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber plasticizer which is difficult to extract into oily substances and improves the cold resistance of rubber and the workability in winter, and a rubber composition containing the same.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
As a technique for improving the cold resistance of rubber, a method of adding a plasticizer such as a phthalic acid ester, an adipic acid ester, or a polyethylene glycol fatty acid ester is known. However, these conventional plasticizers have a problem that they are extracted when they come into contact with an oily substance such as grease and volatilize at high temperatures, impairing the initial cold resistance. Further, although polyester plasticizers are less likely to be extracted or volatilized, there is also a problem that the original cold resistance is poor.

Techniques for solving these problems are disclosed in JP-A-61-145236 and JP-A-7-292235. In these techniques, a chloroprene rubber system is used in the range of -30 ° C to 0 ° C. The phenomenon that the rubber becomes hard at temperature can be seen.

The object of the present invention is that it is difficult to be extracted even when it comes into contact with an oily substance, and is hard to volatilize even at high temperatures, and the cold resistance of the rubber, particularly in the chloroprene rubber system, at temperatures around -30 ° C to 0 ° C. It is an object of the present invention to provide a plasticizer for rubber and a rubber composition which can improve the cold resistance of rubber and have excellent workability in winter.

[0005]

The present invention relates to a rubber plasticizer comprising an ester of a glycol represented by the formula (I) having a number average molecular weight of 200 to 5,000 and a branched fatty acid having 6 to 16 carbon atoms, and a plasticizer for rubber. Provided is a rubber composition containing 3 to 50 parts by weight of a plasticizer for rubber based on 100 parts by weight of rubber.

[0006]

[Chemical 2]

[Wherein, X is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, a is a number of 0 to 2, m and n are n / (m +
n) = 0.03 to 0.5 and consisting indicate the number, and oxytetramethylene group, (CH ₂₎ a group represented by _a CH (X) CH ₂ O may be random addition in block addition. However,
When a is 2, X is not a hydrogen atom. ]

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The plasticizer of the present invention has the formula (I) having a number average molecular weight of 200 to 5,000 as determined from a hydroxyl value.
It is an ester of a glycol represented by and a branched fatty acid having 6 to 16 carbon atoms and preferably contains 75% by weight or more of a diester.

The number average molecular weight of the glycol represented by the formula (I) in the plasticizer of the present invention is from 200 to 200 from the viewpoint of difficulty in extraction to oily substances, difficulty in volatilization at high temperature, and cold resistance. 5000, preferably 300-
3000, more preferably 400 to 2000.

In formula (I), (CH ₂ ) _a CH (X)
As the group represented by CH ₂ O, a group in which X is a methyl group and a is 0 to 2 is preferable, a group in which X is a methyl group and a is 0 or 2 is more preferable, and an oxypropylene group is particularly preferable. preferable. From the viewpoint of lowering the freezing point, n / (m + n) is preferably 0.03 to 0.5, more preferably 0.05 to 0.4, and particularly preferably 0.1 to 0.4. From the viewpoint of further lowering the freezing point, m is preferably 3 to 50, and 5
-30 are more preferable, and 8-15 are especially preferable. Further, n is preferably 0.5 to 10, more preferably 1 to 8, and particularly preferably 1 to 5.

The glycol represented by the formula (I) can be synthesized, for example, by randomly polymerizing or block polymerizing tetrahydrofuran and ethylene oxide, propylene oxide, tetrahydro-2-methylfuran or the like. Moreover, a commercial item can also be used.

Examples of the branched fatty acid having 6 to 16 carbon atoms in the plasticizer of the present invention include isohexanoic acid, isoheptanoic acid, 2-ethylhexanoic acid, isononanoic acid, isodecanoic acid, isotridecanoic acid, isomyristic acid, and isopalmitic acid. And the like, and is preferably isoheptanoic acid, 2-ethylhexanoic acid or isononanoic acid, particularly preferably 2-ethylhexanoic acid or isononanoic acid. These may be used alone or in combination of two or more. It is essential that the branched fatty acid has a carbon number in the range of 6 to 16 because problems such as bleeding of the rubber composition do not occur.

The plasticizer of the present invention can be easily synthesized by a known method, for example, by heating a glycol represented by the formula (I), a branched fatty acid, and a metal catalyst such as dibutyltin oxide under heating at a high temperature. You can

The content of the plasticizer of the present invention in the rubber composition is 3 to 50 parts by weight with respect to 100 parts by weight of rubber from the viewpoint of cold resistance, influence on bleeding and other physical properties, and cost. , Preferably 5 to 40 parts by weight, more preferably 10 to 30 parts by weight.

The rubber according to the present invention includes natural rubber (N
R), butadiene rubber (BR), isoprene rubber (I
R), butyl rubber (IIR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NB
R), ethylene propylene rubber (EPDM), chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM), epichlorohydrin rubber (CHR), and the like. CR, CSM, CHR are preferable, and CR is particularly preferable.

The rubber composition of the present invention can be easily produced by an ordinary kneading machine such as a Banbury mixer, a roll or an intensive mixer. In addition to carbon black, silica, and other reinforcing agents, vulcanization accelerators, vulcanizing agents, and other agents that are usually added to rubber, calcium carbonate, talc, clay, and other fillers and colorants, and UV Absorbents, general-purpose plasticizers (phthalic acid-based, trimellitic acid-based, phosphoric acid-based, epoxy-based, etc.) and the like can be appropriately added.

[0017]

EXAMPLES Percentages in the examples are weight percentages unless otherwise stated.

Synthesis Example 1 In the formula (I), X is a methyl group, a is 2 and m is 9
And n is 1.6 and n / (m + n) is 0.15,
Number average molecular weight 800 glycol (PTG-L800,
400 g of Hodogaya Chemical Co., Ltd., 173 g of 2-ethylhexanoic acid, and dibutyltin oxide as a catalyst of 0.
57 g was weighed in a 1-liter four-necked flask, and the esterification reaction was carried out under dehydration at 230 ° C. while blowing nitrogen into the reaction mixture.
After 6 hours, excess 2-ethylhexanoic acid was distilled off to obtain an ester (PTGR8002EH, composition: diester 90%, monoester 10%).

Synthesis Example 2 In the formula (I), X is a methyl group, a is 2 and m is 1.
A glycol having a number average molecular weight of 1,000 (PTG-L1) having a ratio of 1.5, n of 2, and n / (m + n) of 0.15.
000, Hodogaya Chemical Co., Ltd.) 500 g, 2-ethylhexanoic acid 173 g, dibutyltin oxide 0.6
7 g were reacted in the same manner as in Synthesis Example 1 to give an ester (PTGR10002EH, composition: diester 85%,
Monoester 15%) was obtained.

Synthesis Example 3 In the formula (I), X is a methyl group, a is 0 and m is 1
A glycol having a number average molecular weight of 1000 (PPTG10, 0.5, n is 4.5, and n / (m + n) is 0.3).
00, Hodogaya Chemical Co., Ltd. 500g, 2-ethylhexanoic acid 173g, dibutyltin oxide 0.67
g in the same manner as in Synthesis Example 1 to give the ester (P
TGPO10002EH, composition: diester 75%, monoester 25%).

Comparative Synthesis Example 1 321 g of adipic acid, 180 of 1,4-butanediol
58 g of n, n-octanol and 0.55 g of dibutyltin oxide were esterified by the same method as in Synthesis Example 1 and dealcoholated to obtain Polyester A having an average molecular weight of about 2500 calculated from the charged values.

Comparative Synthesis Example 2 513 g of polyoxytetramethylene glycol having a number average molecular weight of 1000, 200 g of lauric acid and 0.7 g of dibutyltin oxide were reacted in the same manner as in Synthesis Example 1,
Ester (PTG1000L, composition: diester 87
%, Monoester 13%).

Comparative Synthesis Example 3 Polypropylene glycol 400 having a number average molecular weight of 600
g, 230 g of 2-ethylhexanoic acid, and 0.6 g of dibutyltin oxide were reacted in the same manner as in Synthesis Example 1 to obtain an ester (PPG2EH, composition: diester 96%, monoester 4%).

Examples 1 to 6 and Comparative Examples 1 to 7 The esters obtained in Synthetic Examples 1 to 3 and Comparative Synthetic Examples 1 to 3 or di2-ethylhexyl adipate commonly used for improving cold resistance are plasticizers. A rubber composition having the following composition was prepared using various CR-based rubbers shown in Table 1.
Vulcanization was performed at 0 ° C. for 10 minutes to prepare a test piece having a thickness of 2 mm. With respect to this test piece, cold resistance, grease extractability, heat resistance, bleeding, pour point, and fluidity after storage in a refrigerator were evaluated by the following methods. The results are shown in Table 1.

<Rubber composition> CR rubber 100.0 parts by weight SRF carbon ^{* 1} 60.0 parts by weight Anti-PA PA ^{* 2} 5.0 parts by weight Magnesium oxide 4.0 parts by weight Zinc oxide 5.0 parts by weight Stearin Acid 2.0 parts by weight Vulcanization accelerator 22 ^{* 3} 0.5 parts by weight Plasticizer 30.0 parts by weight * 1 SRF carbon: carbon black SRF * 2 Old PA: N-phenyl-α-naphthylamine * 3 Vulcanization Accelerator 22: Ethylenethiourea <Cold resistance> JIS K-6301 (New JIS K-62
Cold resistance was evaluated by the Gehman twist test according to the method of 61). T100, T10, T5, and T2 have a twist modulus of 100 times and 10 times, respectively, compared to normal temperature (23 ° C).
At a temperature of 5 times and 2 times, the lower the number, the better the cold resistance.

<Grease Extractability> Grease was applied to a test piece cut into 10 × 10 cm to a thickness of 20 mm and left in a thermostat at 120 ° C. for 50 hours. After that, wipe the grease off at room temperature and remove the test piece with JI.
It was evaluated by the method of SK-6301 (new JIS K-6261). The grease extractability of the plasticizer in the rubber composition can be judged by the evaluation of cold resistance, and the more difficult it is to extract into grease, the better the cold resistance after extraction with grease is.

<Heat Resistance> The test piece was cut into a No. 3 dumbbell mold and left in a thermostat at 120 ° C. for 100 hours to measure the volatile content from the weight change. The lower the volatile content, the better the heat resistance.

<Bleed> The test piece was stored in an atmosphere of 40 ° C. for 7 days, the surface condition of the test piece was visually observed, and evaluated according to the following criteria.

◯: No bleeding of the plasticizer is seen Δ: There is some bleeding ×: Surface bleeding is severe <Pour point> The plasticizer is half the height in a glass tube having a diameter of about 5 mm and a length of about 60 mm. After encapsulating it in a dry ice + ethanol system and solidifying it at -70 ° C, the temperature of the glass tube is raised at a rate of 2 ° C / minute, and the temperature at which the plasticizer in the glass tube flows out is measured. The pour point.

<Fluidity after Storage in Refrigerator> The plasticizer was put in a 50 mL sample tube and stored in a refrigerator at 5 ° C. for 24 hours, and the state of the plasticizer was evaluated according to the following criteria.

[0031] ◎: transparent and fluid ○: Suspended and opaque, but fluid Δ: Partially solidified but fluidized X: Almost solidified and does not flow

[0032]

[Table 1]

* 1: Mercaptan modified CR manufactured by Denki Kagaku Co., Ltd. * 2: Zantogen modified CR manufactured by Denki Kagaku Co., Ltd. * 3: Sulfur modified CR manufactured by Denki Kagaku Kogyo * 4: DuPont Dow Elastomer Japan (Showa D & D Manufacturing Co., Ltd. mercaptan modified CR)

[0034]

EFFECTS OF THE INVENTION The rubber composition of the present invention is excellent in flexibility at low temperature, especially at T2 and T5, less extracted by oily substances such as grease, and less likely to volatilize at high temperature, so that it has cold resistance. Is excellent in holding. Further, it does not solidify even in the winter, and has excellent winter workability.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 71:02) (C08L 21/00 71:02) (72) Inventor Isao Nishi Minato 1334 Wakayama City Wakayama Prefecture Kao Corporation Research Laboratory (72) Inventor Tetsuo Takano 1334 Minato Wakayama, Wakayama Prefecture Kao Corporation Research Laboratory (72) Inventor Yasushi Abe 2209 Oumi, Aomi Town, Nishikaibiki-gun, Niigata Electric Chemical Industry Co., Ltd. Aomi Factory (72) Inventor Nobuhiko Fujii 2209 Aomi, Aomi-cho, Aomi-cho, Nishikubiki-gun, Niigata Electrochemical Industry Co., Ltd.Aomi Plant Inner F-term (reference) 4J002 AC011 AC031 AC071 AC081 AC091 BB151 BB181 BB271 CH021 CH022 CH041 EH036 FD010 FD020 FD021 FD022 FD026

Claims (4)

[Claims] 1. A number average molecular weight of 200 represented by the formula (I).
A plasticizer for rubber comprising an ester of ˜5000 glycol and branched fatty acid having 6 to 16 carbon atoms. [Chemical 1] [In the formula, X is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms,
a is a number from 0 to 2, m and n are n / (m + n) = 0.0
The oxytetramethylene group and the group represented by (CH ₂ ) _a CH (X) CH ₂ O may be block-added or random-added. However, when a is 2, X is not a hydrogen atom. ] 2. The rubber plasticizer according to claim 1, wherein the branched fatty acid is 2-ethylhexanoic acid, isononanoic acid, or a mixture thereof. 3. A rubber 1 containing the plasticizer according to claim 1 or 2.
A rubber composition containing 3 to 50 parts by weight with respect to 00 parts by weight. 4. The rubber is chloroprene rubber.
The rubber composition described.