JP2022123161A - Rubber composition, unvulcanized mold using rubber composition, vulcanizate and vulcanizate mold - Google Patents

Abstract

To provide a rubber composition excellent in flame retardance without deteriorating mechanical strength, its un-vulcanizate mold, a vulcanizate and a vulcanizate mold made of the vulcanizate.SOLUTION: A rubber composition containing 10 to 120 pts.mass of carbon black relative to 100 pts.mass of a blend polymer made of 20 to 80 parts mass of a copolymer (A) containing chloroprene monomer units and acrylonitrile monomer units, and 20 to 80 parts by mass of soft polyvinyl chloride (B) and containing 7 to 30% by mass of acrylonitrile monomer units in 100 mass% of the copolymer (A).SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a rubber composition excellent in tensile properties and flame retardancy, an unvulcanized molded product, a vulcanized product, and a vulcanized molded product using the rubber composition.

Chloroprene rubber is excellent in mechanical strength, heat resistance and oil resistance, and is widely used as a material for industrial rubber parts due to its good balance of these physical properties. In addition, chloroprene rubber is also characterized by excellent flame retardancy, and is suitably used in rubber parts for buildings, constructions, ships, railroads, coal mines, automobiles, etc. that require flame retardancy. On the other hand, in recent years, the performance required for these rubber parts has increased remarkably, and in addition to the above-mentioned mechanical strength, outstanding flame retardancy is required.

Therefore, in order to improve the flame retardancy of chloroprene rubber compositions and rubber parts, conventional methods have been taken to add various flame retardants. There is known a means for achieving flame retardancy by adding antimony (see Patent Document 1).

In addition, there is known a method for improving flame retardancy by adding a predetermined amount of red phosphorus or a silane coupling agent together with an excessive amount of metal hydrate such as magnesium hydroxide to chloroprene rubber (Patent Documents 2 and 3). reference).

JP 2011-127047 A JP-A-2005-146256 JP-A-2007-23102

In the methods described in the above-mentioned Patent Documents 1 to 3, a method of adding a plastic flame retardant or adding an excessive amount of a specific flame retardant is adopted, so a decrease in mechanical strength cannot be avoided. It was difficult to strike a balance between flame retardancy and mechanical strength. Therefore, in order to obtain industrial rubber parts with excellent flame retardancy, the mechanical strength is sacrificed, which inevitably limits the technical application range.

Therefore, the present invention provides a rubber composition excellent in flame retardancy without lowering mechanical strength, an unvulcanized molded product thereof, a vulcanized product thereof, and a vulcanized molded product formed from the vulcanized product. The main purpose is to

In the present invention, a blend of 20 to 80 parts by mass of a copolymer (A) containing chloroprene monomer units and acrylonitrile monomer units and 20 to 80 parts by mass of flexible polyvinyl chloride (B). Provide a rubber composition containing 10 to 120 parts by mass of carbon black with respect to 100 parts by mass of the polymer, and containing 7 to 30% by mass of acrylonitrile monomer units in 100% by mass of the copolymer (A). .
In this rubber composition, the soft polyvinyl chloride (B) may have a degree of polymerization of 300-3000.

Further, the soft polyvinyl chloride constituting the rubber composition may contain 30 to 150 parts by mass of a plasticizer per 100 parts by mass of polyvinyl chloride.
The plasticizers added at this time include phthalate plasticizers, adipic acid plasticizers, chlorinated paraffin plasticizers, sebacic acid plasticizers, polyester plasticizers, phosphate plasticizers, poly At least one compound selected from ether ester plasticizers and trimellitic acid plasticizers can be used.

An unvulcanized article according to the present invention is obtained by molding the rubber composition described above. Further, the vulcanizate according to the present invention is obtained by vulcanizing a rubber composition, and the vulcanizate molding according to the present invention comprises the vulcanizate.

According to the present invention, a rubber composition excellent in flame retardancy without lowering mechanical strength, an unvulcanized molded product thereof, a vulcanized product thereof, and a vulcanized product molded product comprising the vulcanized product can be obtained. .

DETAILED DESCRIPTION OF THE INVENTION Embodiments for carrying out the present invention will be described in detail below. In addition, this invention is not limited to embodiment described below.

(First embodiment)
<Rubber composition>
First, the rubber composition of the first embodiment of the present invention will be described. The rubber composition of the present embodiment is mainly composed of 20 to 80 parts by mass of a copolymer (A) containing chloroprene monomer units and acrylonitrile monomer units and 20 to 80 parts by mass of soft polyvinyl chloride (B). It contains 10 to 120 parts by mass of carbon black with respect to 100 parts by mass of the blend polymer contained as a component. Each component will be described in detail below.

(1) Copolymer (A)
The copolymer (A) contained in the rubber composition of the present embodiment is obtained by copolymerizing at least a chloroprene (2-chloro-1,3-butadiene) monomer and an acrylonitrile monomer. , which has 7 to 30% by mass of acrylonitrile monomer units in its main chain.

The monomer to be copolymerized is not limited to one type, and may be a copolymer of three or more types of monomers including chloroprene and acrylonitrile. It is not particularly limited. Examples of monomers to be copolymerized include esters of acrylic acid such as methyl acrylate, butyl acrylate and 2-ethylhexyl acrylate, and methacrylic acids such as methyl methacrylate, butyl methacrylate and 2-ethylhexyl methacrylate. esters, hydroxy (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxymethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2,3-dichloro-1,3 -butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, ethylene, styrene and the like.

The amount of acrylonitrile monomer units contained in the copolymer (A) is 7 to 30% by mass, preferably 10 to 27% by mass, more preferably 17 to 27%, based on the total amount of the copolymer (A). % by mass. If the amount of acrylonitrile monomer units is less than 7% by mass, the resulting vulcanizate will have low tensile properties, and if it exceeds 30% by mass, the resulting vulcanizate will not have improved flame retardancy.

The amount of acrylonitrile monomer units contained in the copolymer (A) can be calculated from the content of nitrogen atoms in the polymer. Specifically, 100 mg of copolymer (A) is measured for nitrogen atom content using an elemental analyzer (Sumigraph 220F: manufactured by Sumika Analysis Center Co., Ltd.), and the unsaturated nitrile monomer unit is calculated. do it.
The measurement conditions for elemental analysis are as follows. The electric furnace temperature is set to 900°C for the reactor, 600°C for the reduction furnace, 70°C for the column temperature, and 100°C for the detector temperature, and 0.2 ml/min of oxygen as combustion gas and 80 ml/min of helium as carrier gas are flowed. . A calibration curve is prepared using aspartic acid (10.52%) with a known nitrogen content as a standard substance.

The method for polymerizing the copolymer (A) is not particularly limited, but radical polymerization is preferred. Examples of radical polymerization include solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, etc. Among these, emulsion polymerization is preferred.

The polymerization initiator used for emulsion polymerization is not particularly limited, and known polymerization initiators generally used for emulsion polymerization of chloroprene monomers, such as potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, t - Organic peroxides such as butyl hydroperoxide are used.

The emulsifier used for emulsion polymerization is not particularly limited, and known emulsifiers generally used for emulsion polymerization of chloroprene monomers, such as alkali metal salts of saturated or unsaturated fatty acids having 6 to 22 carbon atoms, rosin acid or Alkali metal salts of disproportionated rosin acid and alkali metal salts of formalin condensate of β-naphthalenesulfonic acid are used.

The molecular weight modifier used for emulsion polymerization is not particularly limited, and known molecular weight modifiers generally used for emulsion polymerization of chloroprene monomers, such as n-dodecylmercaptan, t-dodecylmercaptan, n-octylmercaptan and the like. long-chain alkyl mercaptans, xanthogen compounds such as diisopropyl xanthogen disulfide and diethyl xanthogen disulfide, iodoform, benzyl 1-pyrrole dithiocarbamate (also known as benzyl 1-pyrrole carbodithioate), benzylphenyl carbodithioate, 1-benzyl-N,N Dimethyl-4-aminodithiobenzoate, 1-benzyl-4-methoxydithiobenzoate, 1-phenylethylimidazole dithiocarbamate (alias 1-phenylethylimidazole carbodithioate), benzyl-1-(2-pyrrolidinone) dithiocarbamate (alias benzyl-1-(2-pyrrolidinone) carbodithioate), benzyl phthalimidyl dithiocarbamate (also known as benzyl phthalimidyl carbodithioate), 2-cyanoprop-2-yl-1-pyrrole dithiocarbamate (also known as 2-cyanoprop- 2-yl-1-pyrrolecarbodithioate), 2-cyanobut-2-yl-1-pyrroledithiocarbamate (also known as 2-cyanobut-2-yl-1-pyrrolecarbodithioate), benzyl-1-imidazole dithiocarbamate (aka benzyl-1-imidazolecarbodithioate), 2-cyanoprop-2-yl-N,N-dimethyldithiocarbamate, benzyl-N,N-diethyldithiocarbamate, cyanomethyl-1-(2-pyrrolidone)dithiocarbamate, 2-(ethoxycarbonylbenzyl)prop-2-yl-N,N-diethyldithiocarbamate, 1-phenylethyldithiobenzoate, 2-phenylprop-2-yldithiobenzoate, 1-acetate-1-yl-ethyldithiobenzoate , 1-(4-methoxyphenyl)ethyldithiobenzoate, benzyldithioacetate, ethoxycarbonylmethyldithioacetate, 2-(ethoxycarbonyl)prop-2-yldithiobenzoate, 2-cyanoprop-2-yldithiobenzoate, t- Butyl dithiobenzoate, 2,4,4-trimethylpent-2-yl dithiobenzoate, 2-(4-chlorophenyl)-prop-2-yl dithiobenzoate 3-vinylbenzyldithiobenzoate, 4-vinylbenzyldithiobenzoate, benzyldiethoxyphosphinyldithioformate, t-butyltrithioperbenzoate, 2-phenylprop-2-yl-4-chlorodithiobenzoate, naphthalene- 1-carboxylic acid-1-methyl-1-phenyl-ethyl ester, 4-cyano-4-methyl-4-thiobenzylsulfanylbutyric acid, dibenzyltetrathioterephthalate, carboxymethyldithiobenzoate, poly (ethylene oxide), poly(ethylene oxide) with 4-cyano-4-methyl-4-thiobenzylsulfanylbutyric acid end groups, 2-[(2-phenylethanethiol)sulfanyl]propanoic acid, 2-[(2 -phenylethanethiol)sulfanyl]succinic acid, 3,5-dimethyl-1H-pyrazole-1-carbodithioate potassium, cyanomethyl-3,5-dimethyl-1H-pyrazole-1-carbodithioate, cyanomethylmethyl-( phenyl)dithiocarbamate, benzyl-4-chlorodithiobenzoate, phenylmethyl-4-chlorodithiobenzoate, 4-nitrobenzyl-4-chlorodithiobenzoate, phenylprop-2-yl-4-chlorodithiobenzoate, 1-cyano- 1-methylethyl-4-chlorodithiobenzoate, 3-chloro-2-butenyl-4-chlorodithiobenzoate, 2-chloro-2-butenyldithiobenzoate, benzyldithioacetate, 3-chloro-2-butenyl-1H pyrrole -1-dithiocarboxylic acid, 2-cyanobutan-2-yl-4-chloro-3,5-dimethyl-1H-pyrazole-1-carbodithioate, cyanomethylmethyl (phenyl) carbamodithioate, 2-cyano- 2-propyldodecyltrithiocarbonate, dibenzyltrithiocarbonate, butylbenzyltrithiocarbonate, 2-[[(butylthio)thioxomethyl]thio]propionic acid, 2-[[(dodecylthio)thioxomethyl]thio]propionic acid , 2-[[(butylthio)thioxomethyl]thio]succinic acid, 2-[[(dodecylthio)thioxomethyl]thio]succinic acid, 2-[[(dodecylthio)thioxomethyl]thio]-2-methylpropionic acid, 2,2 ′-[carbonothioylbis(thio)]bis[2-methylpropionic acid], 2-amino-1-methyl-2-o xoethylbutyltrithiocarbonate, benzyl-2-[(2-hydroxyethyl)amino]-1-methyl-2-oxoethyltrithiocarbonate, 3-[[[(t-butyl)thio]thioxomethyl]thio ] Thiocarbonyl compounds such as propionic acid, cyanomethyldodecyltrithiocarbonate, diethylaminobenzyltrithiocarbonate and dibutylaminobenzyltrithiocarbonate are used.

Although the polymerization temperature and the final conversion rate of chloroprene and acrylonitrile are not particularly limited, the polymerization temperature is preferably 0 to 50°C, more preferably 20 to 50°C. Further, it is preferable that the final conversion of chloroprene and acrylonitrile be in the range of 40 to 95% by mass. In order to adjust the final conversion, a polymerization inhibitor for stopping the polymerization reaction may be added to terminate the polymerization when the desired conversion is achieved.

The polymerization inhibitor is not particularly limited, and known polymerization inhibitors generally used for emulsion polymerization of chloroprene monomers, such as thiodiphenylamine, 4-tert-butylcatechol, 2,2-methylenebis-4-methyl- 6-tert-butylphenol is used.

Unreacted chloroprene and acrylonitrile are removed by, for example, a steam stripping method, then the pH is adjusted, and the copolymer (A) is obtained through conventional steps such as freezing and coagulation, washing with water, and drying with hot air.

(2) Soft polyvinyl chloride (B)
The soft polyvinyl chloride contained in the rubber composition of the present embodiment is obtained by plasticizing polyvinyl chloride with a plasticizer. It is something to do.
Commercially available polyvinyl chloride can be used for the soft polyvinyl chloride. For the purpose of balancing the tensile properties and flame retardancy of the resulting vulcanizate, those having a degree of polymerization of 300 to 3000 are used. is preferred, more preferably 500 to 2500.

Plasticizers used to obtain soft polyvinyl chloride include phthalate plasticizers, adipic acid plasticizers, chlorinated paraffin plasticizers, sebacic acid plasticizers, polyester plasticizers, and phosphate ester plasticizers. plasticizers, polyether ester plasticizers, trimellitic acid plasticizers, and the like, and these can be used singly or in combination.

Specific examples of phthalate plasticizers include diisononyl phthalate, dibutyl phthalate, dioctyl phthalate, and diundecyl phthalate. Specific examples of adipic acid-based plasticizers include dioctyl adipate, dibutyl adipate, diisononyl adipate, and diisodecyl adipate.

Further, as the chlorinated paraffin-based plasticizer, specifically, a chlorinated paraffin having a chlorination rate of 40 to 70% and having C10 to C30 and the like can be mentioned. The chlorination rate can be quantified by the oxygen flask method according to JIS-K7229. Specific examples of sebacic acid plasticizers include dioctyl sebacic acid, dimethyl sebacic acid, diethyl sebacic acid, dibutyl sebacic acid, diisopropyl sebacic acid, and dicapryl sebacic acid.

Specific examples of polyester plasticizers include adipic acid-based polyesters and phthalic acid-based polyesters. Specific examples of phosphate plasticizers include tricresol phosphate, tributyl phosphate, trixylenyl phosphate, tris(2-ethylhexyl) phosphate, triphenyl phosphate, and cresyl diphenyl phosphate.

Specific examples of polyether ester plasticizers include adipate ether ester plasticizers, epoxy ester plasticizers, and phthalate ether ester plasticizers. Specific examples of trimellitic acid-based plasticizers include trimethyl trimellitate, tris-2-ethylhexyl trimellitate, isononyl trimellitate, and isooctyl trimellitate.

The amount of the plasticizer added to the flexible polyvinyl chloride (B) is preferably 30 to 150 parts by mass, more preferably 50 to 120 parts by mass, per 100 parts by mass of polyvinyl chloride. If the amount of the plasticizer is 30 parts by mass or more, the polyvinyl chloride can be sufficiently plasticized, and if it is 150 parts by mass or less, the plasticizer will not bleed out onto the surface of the resulting vulcanizate. , the flame retardancy does not decrease. As such soft polyvinyl chloride, a soft vinyl chloride resin manufactured by Mitsubishi Chemical Corporation and the like are known.

(3) Blend polymer The blend polymer is obtained by kneading the aforementioned copolymer (A) and soft polyvinyl chloride (B) as main components. The blend ratio of the copolymer (A) and the flexible polyvinyl chloride (B) is in the range of 20 to 80 parts by weight of the copolymer (A) and 20 to 80 parts by weight of the flexible polyvinyl chloride (B). Preferably, the copolymer (A) is 40-80 parts by mass and the flexible polyvinyl chloride (B) is 20-60 parts by mass.

If the ratio of the copolymer (A) constituting the blend polymer is lower than 20 parts by mass, the effect of improving the breaking elongation of the tensile properties of the resulting vulcanizate is reduced. is less effective at improving

(4) Carbon black Carbon black is added to further improve the tensile properties of the resulting unvulcanized moldings and vulcanizates.

As carbon black, any of furnace black by incomplete combustion method, thermal black by thermal decomposition method, channel black, and acetylene black can be used. Furnace blacks include SAF (Super Abrasion Furnace Black), ISAF (Intermediate Super Abrasion Furnace Black), IISAF (Intermediate ISAF), HAF (High Abrasion Furnace Black), MAF (Medium Abrasion Furnace Black), FEF (FastExtruding Furnace Black), SRF (Semi-Reinforcing Furnace Black), GPF (General Purpose Furnace Black), FF (Fine Furnace Black), and CF (Conductive Furnace Black). Thermal black includes FT (Fine Thermal Black) and MT (Medium Thermal Black). Channel black includes EPC (Easy Processing Channel Black), MPC (Medium Processing Channel Black), and ACET (Acetylene Black). Among these carbon blacks, ISAF, HAF, MAF, FEF, SRF, and GPF are preferably used from the viewpoint of securing moldability of the resulting rubber composition.

The amount of carbon black added is 10 to 120 parts by mass, preferably 30 to 100 parts by mass, per 100 parts by mass of the blend polymer. Moreover, carbon black may be blended in multiple types. If the amount of carbon black added is less than 10 parts by mass, the tensile properties of unvulcanized moldings and vulcanized products made from the resulting rubber composition may not be sufficiently improved. On the other hand, if the amount of carbon black added exceeds 120 parts by mass, the resulting unvulcanized molded article and vulcanized article made of the rubber composition may become too hard and lose rubber elasticity. .

(5) Rubber composition The rubber composition is obtained by kneading the aforementioned blend polymer and carbon black at a vulcanization temperature or lower. As a kneading device, there are a Banbury mixer, a kneader mixer, a twin roll, and the like.

As detailed above, the rubber composition of the present embodiment contains a specific copolymer (A) and a specific soft polyvinyl chloride (B) in a specific ratio, and is blended with carbon black. and an unvulcanized molded product and a vulcanized product having excellent tensile properties and flame retardancy can be obtained.

[Other compounds]
In addition to carbon black, the rubber composition may contain plasticizers, vulcanizing agents, vulcanization accelerators, fillers other than carbon black, reinforcing agents, processing aids, anti-aging agents, and the like.

(Second embodiment)
<Unvulcanized molded product, vulcanized product>
Next, the unvulcanized molded product and vulcanized product of the second embodiment of the present invention will be described. Methods for molding the unvulcanized article and the vulcanized article of the present embodiment include methods such as press molding, extrusion molding, and calender molding.

The temperature at which the rubber composition is molded into an unvulcanized article may be appropriately set according to the composition, and is usually 130° C. or less. Also, the temperature at which the rubber composition is vulcanized may be appropriately set in accordance with its composition, and is usually in the range of 140 to 220°C, preferably 150 to 180°C. The vulcanization time may also be appropriately set according to the composition and shape of the rubber composition, and is usually carried out in the range of 10 to 60 minutes.

The unvulcanized molded product and vulcanized product of this embodiment are obtained by molding or vulcanizing the rubber composition of the first embodiment described above, and are excellent in tensile properties and flame retardancy.

EXAMPLES Hereinafter, the effects of the present invention will be specifically described with reference to examples and comparative examples of the present invention.

<Production of copolymer (A)-1>
<Production Example 1>
<Acrylonitrile monomer unit content 19.1% by mass>
10 parts by mass of chloroprene monomer, 39 parts by mass of acrylonitrile monomer, 0.5 parts by mass of diethylxanthogen disulfide, 200 parts by mass of pure water, and rosin acid were placed in a 3-liter polymerization vessel equipped with a heating/cooling jacket and a stirrer. 5.00 parts by mass of potassium (manufactured by Harima Kasei Co., Ltd.), 0.40 parts by mass of sodium hydroxide, and 2.0 parts by mass of sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Corporation) were added. 0.1 part by mass of potassium persulfate was added as a polymerization initiator, and polymerization was carried out at a polymerization temperature of 40° C. under a nitrogen stream. 51 parts by mass of chloroprene monomer was added, and the addition was started 20 seconds after the start of polymerization. It was done continuously by readjusting the flow rate every 10 seconds. When the polymerization rate with respect to the total amount of the chloroprene monomer and the acrylonitrile monomer reached 50%, the polymerization terminator, phenothiazine, was added to terminate the polymerization. Then, a chloroprene-acrylonitrile copolymer latex was obtained by removing unreacted monomers in the reaction solution under reduced pressure.

The polymerization rate of the chloroprene-acrylonitrile copolymer latex was calculated from the dry weight of the air-dried chloroprene-acrylonitrile copolymer latex. Specifically, it was calculated from the following general formula (I). In the formula, the solid content concentration is the solid content concentration (mass %). The total charged amount is the total amount of raw materials, reagents, and solvent (water) charged into the polymerization vessel from the start of polymerization to a certain time. Evaporation residue is the mass of chemicals and raw materials charged from the start of polymerization to a certain time, which do not volatilize under conditions of 130° C. and remain as solids together with the polymer. The amount of charged monomer is the sum of the amount of the monomer initially charged in the polymerization vessel and the amount of the monomer added until a certain time from the start of the polymerization. The term "monomer" as used herein means the total amount of the chloroprene monomer and the acrylonitrile monomer.
Polymerization rate [%] = {(total charged amount [g] x solid concentration [mass%]/100) - (evaporation residue [g])}/monomer charged amount [g] x 100 ( I)

The chloroprene-acrylonitrile copolymer latex obtained by the above method was adjusted to pH 7.0 and freeze-coagulated on a metal plate cooled to -20°C to break emulsification. The obtained sheet was washed with water and dried at 130° C. for 15 minutes to obtain a solid copolymer (A)-1.

The amount of acrylonitrile monomer units contained in copolymer (A)-1 was calculated from the content of nitrogen atoms in copolymer (A)-1. Specifically, in 100 mg of copolymer (A)-1, the nitrogen atom content is measured using an elemental analyzer (Sumigraph 220F: manufactured by Sumika Analysis Center Co., Ltd.), acrylonitrile monomer unit content amount was calculated.
The measurement conditions for elemental analysis were as follows. The electric furnace temperature was set to 900° C. for the reactor, 600° C. for the reduction furnace, 70° C. for the column, and 100° C. for the detector. . A calibration curve was prepared using aspartic acid (10.52%) with a known nitrogen content as a standard substance.

As a result, the acrylonitrile monomer unit content in copolymer (A)-1 was 19.1% by mass.

<Production of copolymer (A)-2>
<Production Example 2>
<Acrylonitrile monomer unit content 9.9% by mass>
24 parts by mass of chloroprene monomer, 24 parts by mass of acrylonitrile monomer, 0.5 parts by mass of diethylxanthogen disulfide, 200 parts by mass of pure water, and rosin acid were placed in a 3-liter polymerization vessel equipped with a heating/cooling jacket and a stirrer. 5.00 parts by mass of potassium (manufactured by Harima Kasei Co., Ltd.), 0.40 parts by mass of sodium hydroxide, and 2.0 parts by mass of sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Corporation) were added. 0.1 part by mass of potassium persulfate was added as a polymerization initiator, and polymerization was carried out at a polymerization temperature of 40° C. under a nitrogen stream. 52 parts by mass of chloroprene monomer was added, and the addition was started 20 seconds after the start of polymerization. It was done continuously by readjusting the flow rate every 10 seconds. When the polymerization rate with respect to the total amount of the chloroprene monomer and the acrylonitrile monomer reached 50%, the polymerization terminator, phenothiazine, was added to terminate the polymerization. A chloroprene-acrylonitrile copolymer latex was obtained by removing unreacted monomers from the reaction solution under reduced pressure.

The resulting chloroprene-acrylonitrile copolymer latex was freeze-coagulated, washed with water and dried in the same manner as in Production Example 1 to obtain a solid copolymer (A)-2.

As a result of analysis by the same method as in Production Example 1, the acrylonitrile monomer unit content of copolymer (A)-2 was 9.9% by mass.

<Production of copolymer (A)-3>
<Production Example 3>
<Acrylonitrile monomer unit content 27.0% by mass>
A 3-liter polymerization vessel equipped with a heating/cooling jacket and a stirrer was charged with 7 parts by mass of chloroprene monomer, 47 parts by mass of acrylonitrile monomer, 0.5 parts by mass of diethylxanthogen disulfide, 200 parts by mass of pure water, and rosin acid. 5.00 parts by mass of potassium (manufactured by Harima Kasei Co., Ltd.), 0.40 parts by mass of sodium hydroxide, and 2.0 parts by mass of sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Corporation) were added. 0.1 part by mass of potassium persulfate was added as a polymerization initiator, and polymerization was carried out at a polymerization temperature of 40° C. under a nitrogen stream. 46 parts by mass of chloroprene monomer was added, and the addition was started 20 seconds after the start of polymerization. It was done continuously by readjusting the flow rate every 10 seconds. When the polymerization rate with respect to the total amount of the chloroprene monomer and the acrylonitrile monomer reached 50%, the polymerization terminator, phenothiazine, was added to terminate the polymerization. Then, a chloroprene-acrylonitrile copolymer latex was obtained by removing unreacted monomers in the reaction solution under reduced pressure.

The resulting chloroprene-acrylonitrile copolymer latex was freeze-coagulated, washed with water and dried in the same manner as in Production Example 1 to obtain a solid copolymer (A)-3.

As a result of analysis by the same method as in Production Example 1, the acrylonitrile monomer unit content of copolymer (A)-3 was 27.0% by mass.

<Production of copolymer (A)-4>
<Production Example 4>
<Acrylonitrile monomer unit content 0.0% by mass>
100 parts by mass of chloroprene monomer, 0.5 parts by mass of diethylxanthogen disulfide, 200 parts by mass of pure water, and potassium rosinate (manufactured by Harima Kasei Co., Ltd.) were placed in a 3-liter polymerization vessel equipped with a heating/cooling jacket and a stirrer. 5.00 parts by mass, 0.40 parts by mass of sodium hydroxide, and 2.0 parts by mass of sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Corporation) were added. 0.1 part by mass of potassium persulfate was added as a polymerization initiator, and polymerization was carried out at a polymerization temperature of 40° C. under a nitrogen stream. When the polymerization rate of the chloroprene monomer reached 50%, phenothiazine as a polymerization terminator was added to terminate the polymerization. Then, a chloroprene polymer latex was obtained by removing unreacted monomers in the reaction solution under reduced pressure.

The resulting chloroprene polymer latex was freeze-coagulated, washed with water and dried in the same manner as in Production Example 1 to obtain a solid copolymer (A)-4.

As a result of analysis by the same method as in Production Example 1, the acrylonitrile monomer unit content of copolymer (A)-4 was found to be 0.0% by mass.

<Production of copolymer (A)-5>
<Production Example 5>
<5.2% by mass of acrylonitrile monomer unit content>
A 3-liter polymerization vessel equipped with a heating/cooling jacket and a stirrer was charged with 32 parts by mass of chloroprene monomer, 14 parts by mass of acrylonitrile monomer, 0.5 parts by mass of diethylxanthogen disulfide, 200 parts by mass of pure water, and rosin acid. 5.00 parts by mass of potassium (manufactured by Harima Kasei Co., Ltd.), 0.40 parts by mass of sodium hydroxide, and 2.0 parts by mass of sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Corporation) were added. 0.1 part by mass of potassium persulfate was added as a polymerization initiator, and polymerization was carried out at a polymerization temperature of 40° C. under a nitrogen stream. 54 parts by mass of chloroprene monomer was added, and the addition was started 20 seconds after the start of polymerization. It was done continuously by readjusting the flow rate every 10 seconds. When the polymerization rate with respect to the total amount of the chloroprene monomer and the acrylonitrile monomer reached 50%, the polymerization terminator, phenothiazine, was added to terminate the polymerization. Then, a chloroprene-acrylonitrile copolymer latex was obtained by removing unreacted monomers in the reaction solution under reduced pressure.

The resulting chloroprene-acrylonitrile copolymer latex was freeze-coagulated, washed with water and dried in the same manner as in Production Example 1 to obtain a solid copolymer (A)-5.

As a result of analysis by the same method as in Production Example 1, the acrylonitrile monomer unit content of copolymer (A)-5 was 5.2% by mass.

<Production of copolymer (A)-6>
<Production Example 6>
<Acrylonitrile monomer unit content 39.6% by mass>
A 3-liter polymerization vessel equipped with a heating/cooling jacket and a stirrer was charged with 3 parts by mass of chloroprene monomer, 59 parts by mass of acrylonitrile monomer, 0.5 parts by mass of diethylxanthogen disulfide, 200 parts by mass of pure water, and rosin acid. 5.00 parts by mass of potassium (manufactured by Harima Kasei Co., Ltd.), 0.40 parts by mass of sodium hydroxide, and 2.0 parts by mass of sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Corporation) were added. 0.1 part by mass of potassium persulfate was added as a polymerization initiator, and polymerization was carried out at a polymerization temperature of 40° C. under a nitrogen stream. 38 parts by mass of chloroprene monomer was added, and the addition was started 20 seconds after the start of polymerization. It was done continuously by readjusting the flow rate every 10 seconds. When the polymerization rate with respect to the total amount of the chloroprene monomer and the acrylonitrile monomer reached 50%, the polymerization terminator, phenothiazine, was added to terminate the polymerization. Then, a chloroprene-acrylonitrile copolymer latex was obtained by removing unreacted monomers in the reaction solution under reduced pressure.

The resulting chloroprene-acrylonitrile copolymer latex was freeze-coagulated, washed with water and dried in the same manner as in Production Example 1 to obtain a solid copolymer (A)-6.

As a result of analysis by the same method as in Production Example 1, the acrylonitrile monomer unit content of copolymer (A)-6 was 39.6% by mass.

<Production of soft polyvinyl chloride (B)-1>
100 parts by mass of polyvinyl chloride having a polymerization degree of 500 (Taiyo Vinyl Co., Ltd., trade name “TH-500”) and 50 parts by mass of diisononyl phthalic acid are kneaded using an 8-inch open roll to form a soft polychloride. Vinyl (B)-1 was obtained.

<Production of soft polyvinyl chloride (B)-2>
100 parts by mass of polyvinyl chloride having a degree of polymerization of 1000 (Taiyo Vinyl Co., Ltd., trade name “TH-1000”) and 50 parts by mass of diisononyl phthalic acid are kneaded using an 8-inch open roll to form a soft polychloride. Vinyl (B)-2 was obtained.

<Production of soft polyvinyl chloride (B)-3>
100 parts by mass of polyvinyl chloride having a degree of polymerization of 2900 (trade name “TH-2800” manufactured by Taiyo Vinyl Co., Ltd.) and 50 parts by mass of diisononylphthalic acid are kneaded using an 8-inch open roll to form a soft polychloride. Vinyl (B)-3 was obtained.

<Production of soft polyvinyl chloride (B)-4>
100 parts by mass of polyvinyl chloride having a polymerization degree of 500 (Taiyo Vinyl Co., Ltd., trade name “TH-500”) and 50 parts by mass of dioctylphthalic acid are kneaded using an 8-inch open roll to form a soft polychloride. Vinyl (B)-4 was obtained.

<Production of soft polyvinyl chloride (B)-5>
100 parts by mass of polyvinyl chloride having a degree of polymerization of 500 (manufactured by Taiyo Vinyl Co., Ltd., trade name “TH-500”) and 50 parts by mass of trimethyl trimellitate are kneaded using an 8-inch open roll to form a soft polyvinyl. Vinyl chloride (B)-4 was obtained.

<Production of soft polyvinyl chloride (B)-6>
100 parts by mass of polyvinyl chloride having a polymerization degree of 500 (Taiyo Vinyl Co., Ltd., trade name “TH-500”) and 110 parts by mass of diisononyl phthalic acid are kneaded using an 8-inch open roll to form a soft polychloride. Vinyl (B)-6 was obtained.

<Production of soft polyvinyl chloride (B)-7>
100 parts by mass of polyvinyl chloride having a degree of polymerization of 500 (Taiyo Vinyl Co., Ltd., trade name “TH-500”) and 20 parts by mass of diisononyl phthalic acid are kneaded using an 8-inch open roll to form a soft polychloride. Vinyl (B)-7 was obtained.

(Example 1)
(Manufacture of rubber composition)
After preparing a blend polymer by blending 60 parts by mass of the copolymer (A) obtained by the above method and 40 parts by mass of the soft polyvinyl chloride (B), The mixture was kneaded using an 8-inch open roll according to the compounding agent composition to obtain a rubber composition.

The obtained rubber composition was molded into a sheet and then press-molded under the conditions of 80° C. for 10 minutes to obtain a sheet-shaped unvulcanized article having a thickness of 2 mm.

Further, the obtained rubber composition was molded into a sheet and then press-molded under conditions of 160° C. for 30 minutes to obtain a sheet-shaped vulcanizate having a thickness of 2 mm.

Test pieces for evaluation were cut out from the unvulcanized moldings and vulcanizates obtained by the above-described methods, and the tensile properties and flame retardancy were evaluated. The test method for each test is as follows.

(1) Tensile properties Using the test pieces prepared above, "tensile strength (TB) and elongation at break (EB)" were evaluated. "Tensile strength (TB) and elongation at break (EB)" were measured according to JIS K6251.

(2) Flame resistance (oxygen index)
Using the test piece prepared above, the oxygen index was determined and flame retardancy was evaluated. "Oxygen index" was measured according to JIS K6269. Here, the higher the value of the oxygen index, the higher the flame retardancy.

(Examples 2 to 11, Comparative Examples 1 to 7)
A rubber composition, an unvulcanized molded product, and a vulcanized product were prepared in the same manner as in Example 1 with the compositions described in Examples and Comparative Examples shown in Tables 1 and 2, and evaluated in the same manner as in Example 1. .

As shown in Table 1, the unvulcanized moldings and vulcanizates made of the rubber compositions of Examples 1 to 11 within the scope of the present invention were excellent in tensile properties and flame retardancy.

On the other hand, in the unvulcanized molded articles and vulcanized products made of the rubber compositions of Comparative Examples 1 to 7, the acrylonitrile monomer unit content of the copolymer (A) is in the range of 7 to 30% by mass. Otherwise, the blend ratio of the copolymer (A) and the soft polyvinyl chloride (B) does not meet the criteria, or the amount of carbon black added to 100 parts by mass of the blend polymer is not in the range of 10 to 120 parts by mass. It was inferior in tensile properties or flame retardancy.

From the above results, according to the present invention, a rubber composition that can be made excellent in tensile properties and flame retardancy, an unvulcanized product molded from the composition, and a vulcanized product from the composition It was confirmed that a vulcanizate was obtained.

The unvulcanized molded product of the present invention can be used as an adhesive protective material such as an adhesive tape, and the vulcanized product can be used as a sealing material for automobiles, a hose material, a rubber mold, a gasket, an industrial cable, and an industrial product. It can be used as industrial rubber parts such as conveyor belts.

Claims (7)

20 to 80 parts by mass of a copolymer (A) containing chloroprene monomer units and acrylonitrile monomer units, and 20 to 80 parts by mass of soft polyvinyl chloride (B) per 100 parts by mass of a blend polymer A rubber composition containing 10 to 120 parts by mass of carbon black and containing 7 to 30% by mass of acrylonitrile monomer units in 100% by mass of the copolymer (A). 2. The rubber composition according to claim 1, wherein the soft polyvinyl chloride (B) has a degree of polymerization of 300-3000. 3. The rubber composition according to claim 1, wherein the soft polyvinyl chloride (B) contains 30 to 150 parts by mass of a plasticizer per 100 parts by mass of polyvinyl chloride. The plasticizers include phthalate plasticizers, adipic acid plasticizers, chlorinated paraffin plasticizers, sebacic acid plasticizers, polyester plasticizers, phosphate plasticizers, polyether ester plasticizers, and 4. The rubber composition according to claim 3, which is at least one compound selected from trimellitic acid plasticizers. An unvulcanized molded article using the rubber composition according to any one of claims 1 to 4. A vulcanizate of the rubber composition according to any one of claims 1 to 4. A vulcanizate molded article using the vulcanizate according to claim 6.