JP5459882B2 - Chloroprene-based vulcanized rubber composition and chloroprene-based vulcanized rubber - Google Patents

Description

  The present invention relates to a polymer for chloroprene-based vulcanized rubber and a method for producing the same, a composition for chloroprene-based vulcanized rubber, and a chloroprene-based vulcanized rubber. More specifically, it has an excellent balance of durability, especially wear resistance and flex resistance, for example, for vulcanization for expansion joints and anti-vibration materials suitable for civil engineering applications such as viaducts, expressways, bridges, etc. The present invention relates to a polymer and a method for producing the same.

  Conventionally, polymers for chloroprene-based vulcanized rubber have good properties such as general rubber properties, weather resistance, heat resistance, and chemical resistance, so the vulcanized rubber is used in automobiles, civil engineering / architecture applications, industrial applications, etc. Widely used. In the fields of expansion joints for viaducts, highways, bridges, etc., bearing rubbers, anti-vibration rubber materials, polymers for chloroprene-based vulcanized rubber are other vulcanized rubber materials such as natural rubber and styrene-butadiene rubber. Compared to the above, since it is excellent in weather resistance, heat resistance and oil resistance, and the rubber obtained by using this is excellent in durability and excellent in total cost performance, it has been used more favorably than before. In addition, on viaducts and expressways, the load on road surface materials becomes severe due to increased traffic volume, increased weight of transport vehicles, and temperature rise due to global warming. -Butadiene rubber is required not only to have weather resistance but also to improve durability, that is, wear resistance and bending fatigue resistance.

  Under such circumstances, the conventional chloroprene-based vulcanized rubber has no problem in weather resistance, but has problems in durability such as wear and damage on the rubber surface after a long period of time.

  As a means to improve the physical properties of vulcanized rubber obtained using chloroprene-based vulcanized rubber polymers while maintaining the balanced basic properties, dialkylxanthogen disulfides have been used as chain transfer agents. A method to be used has been proposed (Japanese Patent Publication No. 60-18585 (Patent Document 1), etc.). In addition, a method for improving mechanical strength such as tear strength and breaking strength by polymerizing at a relatively low temperature using dialkylxanthogen disulfide has been proposed (Japanese Patent Laid-Open No. 10-60049; Patent Document 2). .

  However, in the method using the above-mentioned known dialkylxanthogen disulfides as a chain transfer agent, the durability is not sufficiently improved, and the performance has not been sufficiently satisfied under severe use conditions. For this reason, the vulcanized rubber obtained by using the chloroprene polymer while maintaining the balanced basic characteristics inherent in the use environment, which is becoming increasingly severe, is resistant to wear and bending fatigue. The advent of a polymer for chloroprene-based vulcanized rubber, which has drastically improved durability such as durability, has been desired.

Japanese Patent Publication No. 60-18685 Japanese Patent Laid-Open No. 10-60049

  Accordingly, an object of the present invention is to provide a chloroprene-based vulcanized rubber in which conventional problems of durability, in particular, wear resistance and flex resistance are solved, and chloroprene used as a raw material thereof, for use in viaducts and expansion joints for highways. Another object of the present invention is to provide a polymer for vulcanized rubber, a method for producing the same, and a composition for chloroprene vulcanized rubber.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a production method that gives a polymer having a specific structure even if it is a chloroprene polymer. The present invention has been completed.

  That is, the present invention relates to the following method for producing a polymer for chloroprene-based vulcanized rubber, a polymer obtained by the method, a composition for chloroprene-based vulcanized rubber containing the same, and a chloroprene-based vulcanized rubber.

[1] As monomers, 2-chloro-1,3-butadiene (C-1) 82 to 98% by mass and 2,3-dichloro-1,3-butadiene (C-2) 18 to 2% by mass Or 2-chloro-1,3-butadiene (C-1) 81.9-97.9% by mass and 2,3-dichloro-1,3-butadiene (C-2) 18-2 And 0.1 to 10% by mass of a monomer (C-3) copolymerizable therewith, (C-1) + (C-2) + (C-3) = 100% by mass Used as a chain transfer agent (A) as a formula (I)
(In the formula, R and R ′ each independently represents an aliphatic, aliphatic cyclic or aromatic alkyl group having 1 to 12 carbon atoms.)
The Mooney viscosity (ML _{1 + 4} (100 ° C.)) (B) of the polymer is 100 at a temperature of 30 to 48 ° C. and a polymerization conversion of 55 to 70% at a temperature of 30 to 48 ° C. A method for producing a polymer for a chloroprene-based vulcanized rubber, which is polymerized so as to have a viscosity of ˜135.
[2] The production method according to 1 above, wherein the polymerization is performed so that the Mooney viscosity (ML _{1 + 4} (100 ° C.)) of the polymer (B) is 110 to 130.
[3] The production method according to the above 1 or 2, wherein the amount of 2,3-dichloro-1,3-butadiene (C-2) used is 15 to 5% by mass.
[4] The method according to any one of 1 to 3, wherein the polymerization temperature is 30 to 40 ° C.
[5] The production method according to any one of 1 to 4, wherein polymerization is performed by emulsion polymerization using rosin acid soap and fatty acid soap as an emulsifier.
[6] A polymer for chloroprene-based vulcanized rubber produced by the method according to any one of 1 to 5 above.
[7] Crystallization rate T (T is based on JISK6301) represented by a hardness increase at −10 ° C. of 2,3-dichloro -1,3- butadiene polymerization rate of 3 to 18% by mass. 7. The polymer for chloroprene-based vulcanized rubber as described in 6 above, wherein the initial time (time = 0) measured at −10 ° C. is a time required to increase by 5 points from 60 to 150 hours.
[8] The fraction of each monomer constituting the polymer is 2-chloro-1,3-butadiene (chloroprene) (C-1) 80 when the total amount of all monomers is 100% by mass. Copolymer consisting of ˜97 mass% and 2,3-dichloro-1,3-butadiene (C-2) 20-3 mass%, or 2-chloro-1,3-butadiene (chloroprene) (C-1) 79.8 to 96.8 mass%, 2,3-dichloro-1,3-butadiene (C-2) 20 to 3 mass%, and a monomer (C-3) copolymerizable therewith is 0.2. A copolymer consisting of ˜17% by mass, having a Mooney viscosity (ML _{1 + 4} (100 ° C.)) of the polymer in the range of 100 to 135, represented by an increase in hardness of the dry polymer at −10 ° C. Crystallization rate T (T is increased by 5 points from the initial (time = 0) hardness measured at −10 ° C. according to JISK6301. Required time) is, chloroprene-based vulcanized rubber polymer for 60 to 150 hours.
[9] The polymer for chloroprene-based vulcanized rubber according to any one of the above 6 to 8, which is used for expansion joints or vibration-proof materials for civil engineering.
[10] 100 parts by mass of the polymer according to any one of 6 to 8 above, 0.5 to 6 parts by mass of an acid acceptor, 0.2 to 3 parts by mass of a lubricant, 1 to 5 parts by mass of an anti-aging agent, 10 to 120 parts by mass of carbon black, 0.1 to 20 parts by mass of fillers other than carbon black, 2 to 40 parts by mass of softening agent, 0.2 to 5 parts by mass of processing aid, 0.5 to 10 parts by mass of metal oxide And a composition for chloroprene vulcanized rubber containing 0.5 to 5 parts by mass of a vulcanization accelerator.
[11] A chloroprene-based vulcanized rubber obtained by vulcanizing the chloroprene-based vulcanized rubber composition as described in 10 above.
[12] The chloroprene vulcanized rubber as described in 11 above, having a hardness (durometer A) of 40-80.

The present invention provides an excellent balance of wear resistance and bending fatigue resistance while maintaining the balanced basic characteristics inherent in chloroprene polymers.
Specifically, the excellent balance between wear resistance and flexural fatigue resistance means that the wear resistance is, for example, the Lambourne abrasion test (slip rate 12.5) shown in section 3. (3) in the method of JISK6264. The wear loss amount (cm ³ ) after 4000 cycles of wear at a load of 40 N) is 0.55 cm ³ or less, preferably 0.50 cm ³ or less, and the pico wear test shown in 3. (4) abrasion loss after abrasion number 240 cycles in (cm ³⁾ is 0.13 cm ³ or less, preferably 0.12 cm ³ or less, and, when the bending fatigue resistance was measured according to the method of JISK6260, room temperature The number of times required for the initial crack generation in the above is 1.5 million times or more, preferably 1.8 million times or more, and the number of times required for crack growth from 2 mm to 15 mm is 30,000 times or more, preferably 3 5 shows a more than million times.
The chloroprene-based vulcanized rubber composition of the present invention is used for applications that require a high degree of durability, such as expansion joints for high bridges, highways, etc., air springs, anti-vibration rubbers, bearing rubbers, various joints, etc. can do.

As the method for producing the polymer of the present invention, emulsion polymerization, solution polymerization and the like can be employed.
In particular, aqueous emulsion polymerization is preferred industrially. As the emulsifier in the emulsion polymerization method, ordinary rosin acid soap and fatty acid soap can be used in combination. About rosin acid soap, it is preferable to use the sodium and / or potassium salt of disproportionated rosin acid from the viewpoint of color stability. As for the usage-amount of rosin acid soap, 3-8 mass parts is preferable with respect to 100 mass parts of monomers. If it is 3 parts by mass or more, emulsification failure is unlikely to occur, and problems such as deterioration in polymerization heat generation control and formation of aggregates are preferable. If it is 8 parts by mass or less, the polymer does not stick due to residual rosin acid, and processing and operability with a roll, Banbury mixer, etc. do not deteriorate during separation and drying of the polymer from the emulsion. ,preferable.

The fatty acid soap is preferably used in the case of high viscosity, particularly the polymer of the present invention, from the viewpoint of enhancing fluidity during the kneading and molding of the polymer. The amount of fatty acid soap used is preferably 0.1 to 1 part by mass with respect to 100 parts by mass of the monomer. If it is 0.1 mass part or more, the effect which improves fluidity | liquidity is enough and preferable. If it is 1 part by mass or less, it does not precipitate on the surface of the dough during kneading and becomes slippery or does not excessively remain on the molding machine and cause soiling. Processing and operation with a roll, Banbury mixer, etc. It is preferable because the property does not deteriorate.
Examples of fatty acids include oleic acid and elaedic acid.

The monomer used in the present invention has good copolymerizability with chloroprene for the purpose of maintaining low temperature characteristics over a wide temperature range, and it is easy to adjust characteristics such as bending fatigue resistance. -Dichloro-1,3-butadiene is preferred.
The amount of 2,3-dichloro-1,3-butadiene used in the present invention is preferably 2 to 18% by mass. Furthermore, 5-15 mass% is more preferable. If it is 2% by mass or more, the improvement of the low-temperature characteristics and the bending fatigue resistance is sufficient, and if it is 18% by mass or less, the bending fatigue resistance is good and it does not become brittle at a low temperature.

  Examples of the copolymerizable monomer (C-3) include 1-chloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, acrylic acid and esters thereof, methacrylic acid and esters thereof, and the like. Depending on the case, these may be used in the range of 0.1 to 10% by mass as long as the object of the present invention is not impaired. Two or more types may be used as necessary. If it is 10 mass% or less, for example, wear resistance and elongation are not lowered, and bending fatigue resistance and compression set are not deteriorated, which is preferable.

In the present invention, in order to improve the crosslinking density efficiently and improve the abrasion resistance, the chain transfer agent (A) is represented by the formula (I)
(In the formula, R and R ′ each independently represents an aliphatic, aliphatic cyclic or aromatic alkyl group having 1 to 12 carbon atoms.)
It is necessary to use a dialkylxanthogen disulfide represented by

Examples of such chain transfer agents include diisopropyl xanthogen disulfide, diethyl xanthogen disulfide, dicyclohexyl xanthogen disulfide, dilauryl xanthogen disulfide, dibenzyl xanthogen disulfide, and the like. In combination with the dialkylxanthogen disulfide, sulfur can be used as other chain transfer agent to the extent that the object of the present invention is not impaired.
The amount of the chain transfer agent (A) used is 0.2 to 0.8 parts by mass (or mole part), preferably 0.3 to 0.5 parts by mass when the total monomer is 100 parts by mass. It is.

The polymerization conversion rate of the polymer of the present invention needs to be 55 to 70%. Furthermore, it is preferable that it is 58 to 65%. A polymerization conversion rate of 55% or more is preferable because the yield of the polymer is small, the productivity is deteriorated, and the wear resistance is not deteriorated. If it is 70% or less, the bending fatigue resistance is deteriorated, heat generation at the time of processing is not caused, fluidity at the time of molding is deteriorated, and problems such as premature vulcanization are not caused.
In the present specification, the polymerization conversion rate refers to the disappearance rate due to polymerization of monomers (total). In order to adjust the polymerization conversion within this range, for example, the specific gravity of the emulsion can be monitored.

The Mooney viscosity (ML _{1 + 4} (100 ° C.)) of the conventional chloroprene polymer for vulcanized rubber is 100 or less, but in this case, it is insufficient to improve the wear resistance. On the other hand, a material having a high viscosity was not intentionally used because the emphasis was placed on heat generation during processing and fluidity during molding.
The Mooney viscosity (ML _{1 + 4} (100 ° C.)) of the polymer of the present invention needs to be 100 to 135. Furthermore, 110-130 are preferable. A Mooney viscosity (ML _{1 + 4} (100 ° C.)) of 100 or more is preferable because improvement in wear resistance is sufficient. If the Mooney viscosity (ML _{1 + 4} (100 ° C.)) is 135 or less, the bending fatigue resistance is deteriorated, heat generation at the time of kneading is not caused, and fluidity at the time of molding is deteriorated. This is preferable because it does not cause problems such as vulcanization.
The Mooney viscosity (ML _{1 + 4} (100 ° C.)) as used herein is measured by the method described in the examples. In order to adjust Mooney viscosity to the said range, it can carry out by adjusting the amount of chain transfer agents and a polymerization conversion rate, for example.

In this invention, it is necessary to superpose | polymerize in the temperature range whose polymerization temperature is 30-48 degreeC. Furthermore, it is preferable to polymerize in a temperature range of 30 to 40 ° C. When the polymerization temperature is 30 ° C. or higher, the productivity of the polymer is lowered, the bending fatigue resistance and the compression set are insufficient, the low temperature characteristics, particularly the hardness change at low temperature is large, It is preferable because flexibility is lost and rigidity is not increased. When the polymerization temperature is 48 ° C. or lower, the vapor pressure of the 2-chloro-1,3-butadiene monomer does not increase, the polymerization operation is easy, and mechanical properties such as wear resistance and tensile strength of the polymer are obtained. The characteristics are sufficient.

  As the polymerization initiator, a normal radical polymerization initiator can be used. For example, in the case of emulsion polymerization, an organic or inorganic peroxide such as benzoyl peroxide, potassium persulfate or ammonium persulfate, or an azo compound such as azobisisobutyronitrile is used.

  In general, in the production of a chloroprene polymer, a polymerization terminator is added to stop the reaction when a predetermined polymerization rate is reached for the purpose of obtaining a polymer having a desired molecular weight and distribution. The polymerization terminator is not particularly limited, and commonly used terminators such as phenothiazine, para-t-butylcatechol, hydroquinone, hydroquinone monomethyl ether, diethylhydroxylamine and the like can be used.

Although the chloroprene polymer is generally more durable than natural rubber or styrene-butadiene rubber, it has an unsaturated bond in the polymer and is susceptible to deterioration by oxygen. In the present invention, it is desirable to appropriately use an antioxidant and a stabilizer within the range not impairing the effects of the invention. As the antioxidant, for example, a hindered phenol-based or amine-based antioxidant can be used. Examples of the hindered phenol antioxidant include 2,2′-methylene-bis (4-ethyl-6-tert-butylphenol), 4,4′-methylene-bis (2,6-di-tert-butylphenol). ), the amine antioxidants include alkylated diphenylamine and derivatives thereof, as a stabilizer, and an ultraviolet absorber, for example, 2- (5-methyl-2-hydroxyphenyl) etc. be given benzotriazole Can do.

  Unreacted monomer is removed by, for example, a steam stripping method, and then the pH of the latex is adjusted to 5 to 7 by adding acetic acid or the like, and then polymerized by freezing coagulation, washing with water, drying with hot air, etc. Can be isolated.

The 2,3-dichloro -1,3- butadiene polymerization fraction of the chloroprene-based polymer of the present invention is preferably 3 to 20% by mass, more preferably 3 to 18% by mass. Further, the crystallization rate T expressed by the hardness increase at −10 ° C. of the dry polymer (T is the time required to increase by 5 points from the initial (time = 0) hardness measured at −10 ° C. based on JISK6301. ) Is preferably 60 to 150 hours. Flexibility is sufficient when the crystallization rate T is within this range.

  When the chloroprene polymer produced under the above conditions is 100 parts by mass, the acid acceptor is 0.5 to 6 parts by mass, the lubricant is 0.2 to 3 parts by mass, and the antioxidant is 1 part. To 5 parts by weight, 10 to 120 parts by weight of carbon black, 0.1 to 20 parts by weight of a filler other than carbon black, 2 to 40 parts by weight of a softening agent, 0.2 to 5 parts by weight of a processing aid, A composition obtained by blending 0.5 to 10 parts by mass of a metal oxide and 0.5 to 5 parts by mass of a vulcanization accelerator is provided, vulcanized by a conventional method, and hardness after vulcanization (durometer) By setting A) to 40 to 80, a chloroprene vulcanized rubber having excellent durability such as wear resistance and bending fatigue resistance is also obtained while maintaining the basic characteristics inherent in the chloroprene polymer.

  As the acid acceptor used in the composition of the present invention, magnesium oxide is most preferable, but weak alkaline inorganic substances such as hydrotalcite can be used alone or in combination. The addition amount of the acid acceptor is preferably 0.5 to 6 parts by mass when the chloroprene polymer is 100 parts by mass. If the addition amount of the acid acceptor is less than 0.5 parts by mass, the effect of acid accepting (neutralization) is not sufficient. Conversely, if the amount exceeds 6 parts by mass, the vulcanization rate is reduced, so desired mechanical properties, For example, it is difficult to obtain tensile properties, which is not preferable.

  The lubricant used in the composition of the present invention reduces frictional resistance with a normal processing machine, prevents adhesion, and disperses in unvulcanized rubber to increase fluidity, and is not particularly limited. For example, fatty acids, fatty acid amides, fatty acid esters, high melting point waxes, low molecular weight polyethylene and the like can be used alone or in combination. Examples of fatty acids include stearic acid, examples of fatty acid amides include stearyl amide, and examples of fatty acid esters include n-butyl stearate. The addition amount of the lubricant is preferably 0.2 to 3 parts by mass when the chloroprene polymer is 100 parts by mass. When the addition amount of the lubricant is less than 0.2 parts by mass, adhesion to a molding machine such as a roll cannot be sufficiently reduced. On the other hand, when the amount exceeds 3 parts by mass, the intermolecular force between the polymers is weakened, so that the strength after vulcanization is lowered or the solvent resistance is lowered.

  The anti-aging agent used in the composition of the present invention is roughly classified into an anti-aging agent (heat-resistant anti-aging) for the purpose of imparting heat resistance and an anti-ozone anti-aging agent (ozone anti-aging), and is preferably used in combination. As heat resistant anti-aging, diphenylamines such as octylated diphenylamine, P- (p-toluene-sulfonylamido) diphenylamine and 4,4′-bis (α, α-dimethylbenzyl) diphenylamine are not only heat resistant but also resistant to gold. It is preferably used because it has little mold contamination. As ozone protection, N, N'-diphenyl-p-phenylenediamine (DPPD) and N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD) are preferably used. The addition amount of the antioxidant is preferably 1 to 5 parts by mass when the chloroprene polymer is 100 parts by mass. When the addition amount of the anti-aging agent is less than 1 part by mass, the anti-aging effect is not sufficient. Conversely, when it exceeds 5 parts by mass, vulcanization is inhibited or contamination is deteriorated.

  As carbon black (ASTM old classification) used in the composition of the present invention, N550 (FEF), N762 (SRF), N330 (HAF), N231 (ISAF), etc. can be used alone or in combination. . N762 (SRF) is preferably used because it has a good balance of mechanical properties and the like. In order to further improve the wear resistance, N330 (HAF) is used. The amount of carbon black added is preferably 10 to 120 parts by mass with 100 parts by mass of the chloroprene polymer. If the amount of carbon black added is less than 10 parts by mass, the effect of improving the mechanical properties is insufficient. Conversely, if it exceeds 120 parts by mass, depending on the case, tensile properties, compression set resistance, flex resistance, This is not preferable because the wear resistance is deteriorated.

  As fillers other than carbon black used in the composition of the present invention, silicic anhydride, clay, particularly hard clay, can be used alone or in combination. The amount of filler other than carbon black is preferably 0.1 to 20 parts by mass when the chloroprene polymer is 100 parts by mass. When the amount of filler other than carbon black is less than 0.1 parts by mass, the effect of improving tensile properties and the like (reinforcing effect) is small, and conversely, when it exceeds 20 parts by mass, processability (formulation viscosity) It is not preferable because the reinforcing effect is deteriorated (increased) or the reinforcing effect is decreased.

  As the softening agent used in the composition of the present invention, organic esters such as naphthenes, aromatic petroleum-based process oils, dioctyl phthalate (DOP), dioctyl sebacate (DOS), and dioctyl azelate (DOZ) are used alone. Or in combination. The addition amount of the softening agent is preferably 2 to 40 parts by mass when the chloroprene polymer is 100 parts by mass. If the addition amount is less than 2 parts by mass, the softening effect (plasticization) is insufficient. Conversely, if it exceeds 40 parts by mass, the tensile properties and wear resistance are deteriorated, or the surface is bleed and the appearance is impaired. This is not preferable.

  The processing aids used in the composition of the present invention may be those usually used and mean additives that improve various molding (extrusion, injection, calendar) properties including so-called kneadability. For example, stearic acid, waxes (microcrystalline type is best), and cis-1,4-polybutadiene (high cis) can be used alone or in combination. The addition amount of the processing aid is preferably 0.2 to 5 parts by mass when the chloroprene polymer is 100 parts by mass. If the amount is less than 0.2 parts by mass, the effect is not sufficient. On the other hand, if the amount exceeds 5 parts by mass, mechanical properties such as tensile properties are deteriorated or the surface is bleed and the appearance is impaired.

  The metal oxide used in the composition of the present invention is not particularly limited, and specific examples include zinc oxide, magnesium oxide, lead oxide, trilead tetraoxide, calcium oxide and the like. These may be used in combination of two or more. Moreover, it can also vulcanize more effectively by using together with the following vulcanization accelerator. The addition amount of the metal oxide is preferably 0.5 to 10 parts by mass when the chloroprene polymer is 100 parts by mass. If the amount is less than 0.5 parts by mass, the vulcanization rate is not sufficient. On the other hand, if it exceeds 10 parts by mass, the vulcanization becomes too fast and scorching tends to occur.

  As the vulcanization accelerator, thiourea, guanidine, thiuram, and thiazole vulcanization accelerators generally used for vulcanization of chloroprene rubber can be used, and thiourea type is preferable. Examples of thiourea-based vulcanization accelerators include ethylene thiourea, diethyl thiourea, trimethyl thiourea, trimethyl thiourea, N, N′-diphenyl thiourea, and trimeryl thiourea is particularly preferable. Further, two or more of the vulcanization accelerators listed above may be used in combination. The addition amount of these vulcanization accelerators is preferably 0.5 to 5 parts by mass when the chloroprene polymer is 100 parts by mass. If it is less than 0.5 parts by mass, the accelerating effect is not sufficient. Conversely, if it exceeds 5 parts by mass, vulcanization becomes too fast and scorch is likely to occur, which is not preferable.

Using the above compounding agent, the prepared composition for chloroprene-based vulcanized rubber is kneaded, molded, and vulcanized. Vulcanization can be performed by heating, for example. As heating conditions, it can carry out at 120-170 degreeC for 2 to 60 minutes.
The hardness (durometer A) of the vulcanizate thus obtained is usually preferably 40 to 80 as a range in which sufficient rubber elasticity can be obtained. Furthermore, among the characteristics that are the original objectives of the present invention, if the hardness is less than 40, the tendency to be inferior in wear resistance becomes large. On the other hand, if the hardness is more than 80, the tendency to inferior in bending resistance becomes large.

  Under the above conditions, the produced polymer provides a vulcanized rubber having excellent durability such as wear resistance and bending fatigue resistance while maintaining the basic properties inherent in the chloroprene polymer.

  The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Mooney viscosity:
The Mooney viscosity of the polymers for chloroprene-based vulcanized rubber obtained in the Examples and Comparative Examples of the present invention was measured using a Mooney viscometer at 100 ° C. (after preheating 1 minute and 4 minutes after rotation for 4 minutes). ) The Mooney viscosity ML _{1 + 4} (100 ° C.) of the polymer was measured.

Preparation of chloroprene vulcanized rubber composition:
A composition for chloroprene-based vulcanized rubber was prepared from the polymer for chloroprene-based vulcanized rubber (polymer) obtained in Examples and Comparative Examples of the present invention by the following composition.
(1) Compounding component ratio (parts by mass)
Polymer 100
Stearic acid 0.5
MgO (# 150) 4
Anti-aging agent AD 1) 2
Anti-aging agent 6C 2) 1
Carbon black SRF (N762) 3) 40
Silicic anhydride 4) 10
Dioctyl phthalate 25
Wax 5) 2
ZnO (second type) 6) 5
Sulfur 1
Accelerator DT 7) 0.8
Accelerator TS 8) 0.5
1) Nouchi AD, manufactured by Ouchi Shinsei Chemical Co., Ltd.
2) Nocrack 6C, manufactured by Ouchi Shinsei Chemical Co., Ltd.
3) Show Black N762, Showa Cabot Co., Ltd.
4) NIPSEAL VN3, manufactured by Nippon Silica Co., Ltd.
5) Sunnock, manufactured by Ouchi Shinsei Chemical Co., Ltd.
6) Second kind zinc oxide manufactured by Sakai Chemical Co., Ltd.
7) Ouchi Shinsei Chemical Co., Ltd., Noxeller DT
8) Ouchi Shinsei Chemical Co., Ltd., Noxeller TS

(2) Kneading Banbury (internal volume 1.8L) was used, filling rate 65%, 60 rpm, kneading for 30 seconds, kneading for 90 seconds with addition of compounding agent, 45 seconds after post-kneading, and discharging at 125 to 126 ° C. .

(3) Vulcanization In a conventional press vulcanization, vulcanization was performed by heating at 150 ° C. for 45 minutes. The vulcanized sheet was appropriately cut according to the evaluation item to obtain a test piece.

Measurement of physical properties:
Using the above test pieces, the following physical properties were evaluated.
[Compression set]
According to the method of JISK6262, it measured after 70 degreeC and 96 hours (vulcanization | cure 150 degreeC, 45 minutes).

[2,3-dichloro -1,3- butadiene copolymerization fraction]
Copolymerization composition in the polymer by analyzing residual chloroprene monomer and 2,3-dichloro -1,3- butadiene monomer in the emulsion after polymerization by gas chromatography and subtracting from each charged monomer amount Was calculated.

[Crystalization rate]
The polymer is pressed at 50 ° C. to obtain a sheet having a thickness of 5 mm. This sheet was heated at 70 ° C. for 1 hour, decrystallized, and stored in a low-temperature thermostatic bath at −10 ° C., and the increase in hardness over time was measured based on JISK6301 . The crystallization rate was evaluated by the time required to increase by 5 points or more from the initial hardness (before storage at −10 ° C.).

[Abrasion resistance]
In the method of JISK6264, the amount of wear loss (cm ³ ) after 4000 cycles of wear in the Lambourn wear test (slip rate 12.5, load load 40N) shown in Section 3. ( ³ ) and Section 3. (4) The amount of wear loss (cm ³ ) after 240 cycles of wear in the indicated pico wear test was measured.

[Bending fatigue resistance]
It measured according to the method of JISK6260. The number of times required for initial crack generation at room temperature and the number of times required for crack growth from 2 mm to 15 mm (times) were measured. Evaluation was performed at n = 4.

Example 1:
Using a reactor with an internal volume of 60 liters, 17.6 kg of chloroprene, 2.4 kg of 2,3-dichloro-1,3-butadiene and 16 kg of pure water, disproportionated rosin acid (manufactured by Arakawa Chemical Industries, Ltd., R-300) 510 g, oleic acid 110 g, diethyl xanthogen disulfide 68 g, sodium hydroxide 260 g, β-naphthalene sulfonic acid formalin condensate 200 g sodium salt was emulsified and emulsified, and then potassium persulfate was used as an initiator, nitrogen Polymerization was performed at 35 ° C. in an atmosphere. As soon as the polymerization conversion reached 60%, an emulsion of phenothiazine was immediately added to terminate the polymerization.
Subsequently, unreacted monomer was removed by steam distillation to obtain a polymer emulsion of a chloroprene polymer. A part of this emulsion was collected and adjusted to pH 6.0, and then a chloroprene polymer (A) was obtained by a conventional freeze-coagulation drying method.
The Mooney viscosity (ML _{1 + 4} (100 ° C.)) of the polymer (A) was 122.

Examples 2 and 6:
In Example 1, instead of diethylxanthogen disulfide, diisopropylxanthogen disulfide was used in an amount corresponding to the amount described in Table 1, and the amount of 2,3-dichloro-1,3-butadiene, polymerization temperature, and polymerization conversion were changed. Then, polymerization was performed to obtain a polymer.

Examples 3-5:
In Example 1, the amount of diethyl xanthogen disulfide was changed to the equivalent amount shown in Table 1, the amount of 2,3-dichloro-1,3-butadiene, the polymerization temperature, and the polymerization conversion rate were changed, and the polymerization was conducted. And a polymer was obtained.

Comparative Example 1:
In Example 1, instead of diethylxanthogen disulfide, DDM (n-dodecyl mercaptan) was used in an amount corresponding to the amount described in Table 1, 2,3-dichloro-1,3-butadiene amount, polymerization temperature, polymerization Polymerization was carried out by changing the conversion rate to obtain a polymer.

Comparative Examples 2, 4-5:
In Example 1, the amount of diethyl xanthogen disulfide was changed to the equivalent amount shown in Table 1, the amount of 2,3-dichloro -1,3- butadiene, the polymerization temperature, and the polymerization conversion rate were changed, and the polymerization was conducted. And a polymer was obtained.

Comparative Example 3:
In Example 1, in place of the diethyl xanthogen disulfide, diisopropyl xanthogen disulfide with a substantial amount of the amount described in Table 1, 2,3-dichloro b-1,3-butadiene amount, polymerization temperature, polymerization conversion rate It changed and superposed | polymerized and obtained the polymer.
The results of the above implementation are summarized in Table 1. In addition, all of the polymers of Examples 1 to 6 maintained the balanced basic properties (for example, tensile strength and elongation at break) inherently possessed by the chloroprene polymer.

As is apparent from Table 1, according to the present invention, a polychloroprene vulcanized rubber composition having an excellent balance between wear resistance and flex resistance can be obtained.
The chloroprene-based vulcanized rubber composition of the present invention is used for applications that require a high degree of durability, such as expansion joints for high bridges, highways, etc., air springs, anti-vibration rubbers, bearing rubbers, various joints, etc. can do.

Claims (8)

The fraction of each monomer constituting the polymer is 2-chloro-1,3-butadiene (chloroprene) (C-1) 80 to 97 mass when the total amount of all monomers is 100 mass%. % And 2,3-dichloro-1,3-butadiene (C-2) 20 to 3 mass%, or 2-chloro-1,3-butadiene (chloroprene) (C-1) 79.8 To 96.8% by mass, 2,3-dichloro-1,3-butadiene (C-2) 20 to 3% by mass, and monomer (C-3) copolymerizable therewith 0.2 to 17% by mass The chain transfer agent (A) comprises the formula (I)
(In the formula, R and R ′ each independently represents an aliphatic, aliphatic cyclic or aromatic alkyl group having 1 to 12 carbon atoms.)
A copolymer which is polymerized using a disulfide represented in polymer Mooney viscosity _{(ML 1 + 4 (100 ℃} )) chloroprene-based vulcanized rubber polymer for 100 in the range of 100 to 135 Parts by weight, acid acceptor 0.5-6 parts by weight, lubricant 0.2-3 parts by weight, anti-aging agent 1-5 parts by weight, carbon black 10-120 parts by weight, filler other than carbon black 0.1-0.1 Chloroprene system containing 20 parts by weight, softening agent 2 to 40 parts by weight, processing aid 0.2 to 5 parts by weight, metal oxide 0.5 to 10 parts by weight, and vulcanization accelerator 0.5 to 5 parts by weight Composition for vulcanized rubber.

  Crystallization rate T of the chloroprene-based vulcanized rubber polymer expressed as an increase in hardness at −10 ° C. of the dry polymer (T is the initial (time = 0) hardness measured at −10 ° C. based on JISK6301. The chloroprene-based vulcanized rubber composition according to claim 1, wherein the time required for the temperature to rise by 5 points is 60 to 150 hours. The composition for chloroprene-based vulcanized rubber according to claim 1 or 2, wherein the polymer for chloroprene-based vulcanized rubber has a Mooney viscosity (ML _{1 + 4} (100 ° C)) in the range of 110-130. The chloroprene vulcanized rubber polymer uses 2-chloro-1,3-butadiene (C-1) and 2,3-dichloro-1,3-butadiene (C-2) as monomers. 2-chloro-1,3-butadiene (C-1), 2,3-dichloro-1,3-butadiene (C-2), and a monomer (C-3) copolymerizable therewith The chloroprene vulcanized rubber according to any one of claims 1 to 3 , wherein the chloroprene vulcanized rubber is polymerized at a temperature of 30 to 48 ° C so as to have a polymerization conversion of 55 to 70%. Composition.   The composition for chloroprene-based vulcanized rubber according to claim 4, wherein the polymerization temperature is 30 to 40 ° C.   The chloroprene vulcanized rubber composition according to claim 4 or 5, wherein the chloroprene vulcanized rubber polymer is polymerized by emulsion polymerization using rosin acid soap and fatty acid soap as emulsifiers.   A chloroprene vulcanized rubber obtained by vulcanizing the chloroprene vulcanized rubber composition according to claim 1.   The chloroprene vulcanized rubber according to claim 7, which has a hardness (durometer A) of 40 to 80.