Method for producing elastomer pellets

Abstract

To provide a method for producing elastomer pellets that is capable of suppressing the generation of fluff.SOLUTION: A method for producing elastomer pellets comprises a step of hot-cutting an elastomer. The step of hot-cutting the elastomer includes cooling the elastomer extruded through the die hole with cooling water, and the value of a parameter A represented by general formula (I), A=-X0.41-Y0.36+Z0.71, is 1.8 or less. (In general formula (I), X represents the weight average molecular weight (unit: ten-thousand) of the elastomer, Y represents the shear rate [1 / sec] of the elastomer in the die hole, and Z represents the temperature [°C] of the cooling water for the elastomer.)SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing elastomer pellets. [Background technology]

[0002] One known method for producing elastomer pellets is to hot-cut an elastomer in water, crush it, and dry it (see, for example, Patent Document 1). Patent Document 1 discloses that adding an anti-blocking agent to the elastomer after hot-cutting can produce elastomer pellets in good condition. However, the method for producing elastomer pellets by hot-cutting an elastomer has problems in that froth, which is elastomer fragments generated in the form of powder or strips, is generated and accumulates in pipes, etc., and the froth accumulated in pipes, etc., can become mixed with the pellets together with moisture, deteriorating the quality of products produced from the pellets. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-151519 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to provide a method for producing elastomer pellets that can suppress the generation of froth. [Means for solving the problem]

[0005] As a result of intensive research aimed at solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by hot-cutting an elastomer under conditions in which the values ​​of parameters represented by the weight-average molecular weight of the elastomer, the shear rate of the elastomer in the die hole, and the temperature of the cooling water are within predetermined ranges. Based on this finding, the present invention has been completed.

[0006] [1] A first aspect of the present invention is a method for producing elastomer pellets, comprising a step of hot-cutting an elastomer extruded through a die hole, wherein the step of hot-cutting the elastomer includes cooling the elastomer extruded through the die hole with cooling water, and wherein the value of parameter A represented by the following general formula (I) is 1.8 or less. A=-X 0.41 -Y 0.36 +Z 0.71 …(I) (In the above general formula (I), X is the weight average molecular weight of the elastomer [10,000], Y is the shear rate of the elastomer in the die hole [1 / sec], and Z is the temperature of the cooling water for the elastomer [°C].)

[0007] [2] A second aspect of the present invention is the method for producing elastomer pellets according to the first aspect, wherein the hot cutting is underwater hot cutting.

[0008] [3] A third aspect of the present invention is the method for producing elastomer pellets according to the first or second aspect, wherein the temperature of the cooling water is lower than 40°C.

[0009] [4] A fourth aspect of the present invention is the method for producing elastomer pellets according to any one of the first to third aspects, wherein the weight average molecular weight (Mw) of the elastomer is 200,000 or more.

[0010] [5] A fifth aspect of the present invention is the method for producing elastomer pellets according to any one of the first to fourth aspects, wherein the elastomer is an elastomer containing a conjugated diene compound.

[0011] [6] A sixth aspect of the present invention is the method for producing elastomer pellets according to any one of the first to fourth aspects, wherein the elastomer is an elastomer containing an aromatic vinyl compound.

[0012] [7] A seventh aspect of the present invention is the method for producing elastomer pellets according to any one of the first to fourth aspects, wherein the elastomer is a random copolymer containing aromatic vinyl compound monomer units and conjugated diene compound monomer units.

[0013] [8] An eighth aspect of the present invention is the method for producing elastomer pellets according to the sixth or seventh aspect, wherein the aromatic vinyl compound has a block ratio of 20% or less. [Effects of the Invention]

[0014] According to the present invention, a method for producing elastomer pellets that can suppress the generation of froth can be provided. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a method for underwater hot cutting in an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] The method for producing elastomer pellets in this embodiment includes a step of hot-cutting an elastomer extruded through a die hole of a die, the step of hot-cutting the elastomer including cooling the elastomer extruded through the die hole with cooling water, and the value of parameter A represented by the following general formula (II) is 1.8 or less. A=-X 0.41 -Y 0.36 +Z 0.71 …(II) (In the above general formula (II), X is the weight average molecular weight of the elastomer [10,000], Y is the shear rate of the elastomer in the die hole [1 / sec], and Z is the temperature of the cooling water for the elastomer [°C].)

[0017] <Elastomer> The elastomer used in the present invention is not particularly limited, but is preferably a copolymer containing an aromatic vinyl monomer unit or a conjugated diene monomer unit, more preferably a copolymer containing an aromatic vinyl monomer unit and a conjugated diene monomer unit, and even more preferably a random copolymer containing an aromatic vinyl monomer and a conjugated diene monomer.

[0018] The aromatic vinyl compound for forming the aromatic vinyl monomer unit is not particularly limited, but includes styrene, methylstyrene, ethylstyrene, t-butylstyrene, α-methylstyrene, α-methyl-p-methylstyrene, chlorostyrene, bromostyrene, methoxystyrene, dimethylaminomethylstyrene, dimethylaminoethylstyrene, diethylaminomethylstyrene, diethylaminoethylstyrene, cyanoethylstyrene, vinylnaphthalene, etc. Among these, styrene is preferred. These aromatic vinyl compounds may be used alone or in combination of two or more. It is particularly preferred to use styrene alone as the aromatic vinyl compound.

[0019] The content of aromatic vinyl monomer units in all monomer units constituting the copolymer is 0 to 50% by weight. The content of aromatic vinyl monomer units is not particularly limited as long as it is 0 to 50% by weight, but is preferably 2 to 27% by weight, more preferably 3.5 to 25% by weight, and even more preferably 4.5 to 19% by weight. By setting the content of aromatic vinyl monomer units within the above range, the elastomer pellets can be made to have a high level of balance between low heat buildup, abrasion resistance, and strength properties.

[0020] The conjugated diene compound for forming the conjugated diene monomer unit is not particularly limited, but examples thereof include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 4,5-diethyl-1,3-octadiene, and 3-butyl-1,3-octadiene. Among these, 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is more preferred. These conjugated diene compounds may be used alone or in combination of two or more. It is particularly preferred to use 1,3-butadiene alone as the conjugated diene compound.

[0021] The content of the conjugated diene monomer units in all the monomer units constituting the copolymer is preferably 50 to 100% by weight, more preferably 73 to 98% by weight, even more preferably 75 to 96.5% by weight, and particularly preferably 81 to 95.5% by weight. By setting the content of the conjugated diene monomer units within the above range, the elastomer pellets can be made to have a high level of balance between low heat buildup, abrasion resistance, and strength properties.

[0022] The vinyl bond content in the conjugated diene monomer units in the elastomer used in the present invention is 0 to 70% by weight. The vinyl bond content is not particularly limited as long as it is 0 to 70% by weight, but is preferably 5 to 60% by weight, more preferably 10 to 40% by weight, even more preferably 15 to 35% by weight, and particularly preferably 20 to 32% by weight. By keeping the vinyl bond content within the above range, the obtained elastomer pellets can be highly balanced in terms of low heat buildup, abrasion resistance, and strength properties.

[0023] The elastomer used in the present invention may contain units of a vinyl compound containing a functional group capable of interacting with silica.

[0024] The vinyl compound that contains functional groups that can interact with silica and that can form the unit of the vinyl compound that contains functional groups that can interact with silica can be any compound that contains a functional group that can interact with silica and a vinyl group, and is not particularly limited.Here, the functional group that can interact with silica is the functional group that can form a covalent bond between this functional group and the silica surface, or can form intermolecular forces that are weaker than covalent bonds (for example, ion-dipole interaction, dipole-dipole interaction, hydrogen bond, van der Waals force, etc.).The functional group that can interact with silica is not particularly limited, but can include nitrogen atom-containing functional groups, silicon atom-containing functional groups, oxygen atom-containing functional groups, etc.Among these, silicon atom-containing functional groups are preferred because of their high interaction with silica.

[0025] As a preferred embodiment of the vinyl compound containing a functional group capable of interacting with silica, a vinyl compound containing a silicon atom-containing functional group can be suitably used, for example, a compound represented by the following general formula (1): [ka] In the above general formula (1), X 1 represents a chemical single bond or a hydrocarbylene group, and X 2 , X 3 and X 4 each independently represents a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent.

[0026] In the above general formula (1), X 1 is a chemical single bond or a hydrocarbylene group, preferably a chemical single bond. Examples of the hydrocarbylene group include an alkylene group, an alkenediyl group, an arylene group, and a group in which an arylene group and an alkylene group are bonded together. Examples of alkylene groups include methylene, ethylene, and trimethylene groups. Examples of alkenediyl groups include vinylene and ethylene-1,1-diyl groups. Examples of arylene groups include phenylene, naphthylene, and biphenylene groups. Examples of groups in which an arylene group and an alkylene group are bonded include groups in which a phenylene group and a methylene group are bonded, and groups in which a phenylene group and an ethylene group are bonded. X 1 When is a hydrocarbylene group, X 1 is preferably an arylene group, more preferably a phenylene group.

[0027] In the above general formula (1), X 2 , X 3 and X 4 X each independently represents a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent. 2 , X 3 and X 4 At least one of X is preferably a substituted amino group; 2 , X 3 and X 4 It is more preferable that two of them are substituted amino groups.

[0028] X 2 , X 3 and X 4 As the substituted amino group which can constitute the above, a group represented by the following general formula (2) is preferred. [ka] In the above general formula (2), R 1 and R 2 may or may not be bonded to each other, and R 1 and R 2 If they are not bonded to each other, R 1 and R 2 each independently represents a hydrocarbyl group or a trihydrocarbylsilyl group which may have a substituent, and R 1 and R 2When and are bonded to each other, R 1 and R 2 represents a hydrocarbylene group which may contain at least one atom selected from a nitrogen atom, an oxygen atom, a sulfur atom and a silicon atom.

[0029] R 1 and R 2 Examples of hydrocarbyl groups that can constitute the above include chain alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, and n-octyl; cyclic alkyl groups such as cyclopentyl and cyclohexyl; and aryl groups such as phenyl, benzyl, and naphthyl. Among these, chain alkyl groups are preferred, and methyl or ethyl groups are more preferred. R 1 and R 2 When the hydrocarbyl group that can constitute the above has a substituent, examples thereof include hydrocarbyl groups having a hydrocarbyloxy group as a substituent, and examples of the hydrocarbyl group having a hydrocarbyloxy group as a substituent include alkoxyalkyl groups such as a methoxymethyl group, an ethoxymethyl group, and a methoxyethyl group; and aryloxyalkyl groups such as a phenoxymethyl group.

[0030] R 1 and R 2 Specific examples of the trihydrocarbylsilyl group that can constitute the above group include trialkylsilyl groups such as trimethylsilyl group, triethylsilyl group, and tert-butyldimethylsilyl group.

[0031] R 1 and R 2 When and are bonded to each other, R 1 and R 2Examples of the hydrocarbylene group that can constitute R include alkylene groups such as trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, decamethylene, dodecamethylene, and 2,2,4-trimethylhexane-1,6-diyl; and alkenediyl groups such as pentan-2-ene-1,5-diyl. 1 and R 2 When the hydrocarbylene group that can constitute the formula (I) contains at least one selected from a nitrogen atom, an oxygen atom, a sulfur atom, and a silicon atom, examples of the hydrocarbylene group containing at least one selected from a nitrogen atom, an oxygen atom, a sulfur atom, and a silicon atom include a group represented by -CH=N-CH=CH-, a group represented by -CH=N-CH2-CH2-, a group represented by -CH2-CH2-O-CH2-CH2-, a group represented by -CH2-CH2-S-CH2-CH2-, a group represented by -CH2-CH2-SiH2-CH2-CH2-, a group represented by -CH2-CH2-SiMe2-CH2-CH2-, and a group represented by -CH2-CH2-SiEt2-CH2-CH2-. R 1 and R 2 is an alkyl group, or R 1 and R 2 and preferably bond to each other to form an alkylene group, and R 1 and R 2 is more preferably an alkyl group, and R 1 and R 2 is more preferably a methyl group or an ethyl group.

[0032] In the above general formula (2), R 1 and R 2When is a hydrocarbyl group, specific examples of the group represented by the above general formula (2) include dialkylamino groups such as dimethylamino group, diethylamino group, ethylmethylamino group, di-n-propylamino group, diisopropylamino group, di-n-butylamino group, diisobutylamino group, di-sec-butylamino group, and di-tert-butylamino group; diarylamino groups such as diphenylamino group; etc. Among these, dialkylamino groups are preferred, and dimethylamino group, diethylamino group, and di-n-butylamino group are more preferred.

[0033] In the above general formula (2), R 1 and R 2 When the group represented by the general formula (2) is a hydrocarbyl group having a hydrocarbyloxy group as a substituent, specific examples of the group represented by the general formula (2) include di(alkoxyalkyl)amino groups such as di(methoxymethyl)amino and di(ethoxymethyl)amino.

[0034] In the above general formula (2), R 1 and R 2 When is a trihydrocarbylsilyl group, specific examples of the group represented by the above general formula (2) include trialkylsilyl group-containing amino groups such as a bis(trimethylsilyl)amino group, a bis(tert-butyldimethylsilyl)amino group, and an N-trimethylsilyl-N-methylamino group.

[0035] In the above general formula (2), R 1 and R 2 and (b) are bonded to each other to form a hydrocarbylene group, specific examples of the group represented by the above general formula (2) include 1-alkyleneimino groups such as a 1-trimethyleneimino group, a 1-pyrrolidino group, a 1-piperidino group, a 1-hexamethyleneimino group, a 1-heptamethyleneimino group, a 1-octamethyleneimino group, a 1-decamethyleneimino group, and a 1-dodecamethyleneimino group.

[0036] In the above general formula (2), R 1 and R 2and are bonded to each other to form a hydrocarbylene group containing a nitrogen atom and / or an oxygen atom, specific examples of the group represented by the above general formula (2) include a 1-imidazolyl group, a 4,5-dihydro-1-imidazolyl group, and a morpholino group.

[0037] As the group represented by the above general formula (2), a dialkylamino group or a 1-alkyleneimino group is preferred, a dialkylamino group is more preferred, and a dimethylamino group, a diethylamino group or a di-n-butylamino group is even more preferred.

[0038] In the above general formula (1), X 2 , X 3 and X 4 Examples of hydrocarbyloxy groups that can constitute the above formula include alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, and tert-butoxy; and aryloxy groups such as phenoxy and benzyloxy.

[0039] In the above general formula (1), X 2 , X 3 and X 4 Examples of hydrocarbyl groups that can constitute the above formula include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, and tert-butyl; and aryl groups such as phenyl, 4-methyl-1-phenyl, and benzyl. X 2 , X 3 and X 4 When the hydrocarbyl group that can constitute the above has a substituent, examples thereof include hydrocarbyl groups having a hydrocarbyloxy group as the substituent, and examples thereof include alkoxyalkyl groups such as a methoxymethyl group, an ethoxymethyl group, and an ethoxyethyl group.

[0040] In the above general formula (1), X 1 is a chemical single bond, and X 2 , X 3 and X 4Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (1), when one of the groups is a substituted amino group, include (dialkylamino)dialkylvinylsilanes such as (dimethylamino)dimethylvinylsilane, (ethylmethylamino)dimethylvinylsilane, (di-n-propylamino)dimethylvinylsilane, (diisopropylamino)dimethylvinylsilane, (dimethylamino)diethylvinylsilane, (ethylmethylamino)diethylvinylsilane, (di-n-propylamino)diethylvinylsilane, and (diisopropylamino)diethylvinylsilane; [bis(trimethylsilyl)amino]dimethylvinylsilane, [bis(t-butyldimethylsilyl)amino]dimethylvinylsilane, [bis(trimethylsilyl)amino]diethylvinylsilane, and [bis(t-butyldimethylsilyl)amino]diethylvinylsilane; (trialkylsilyl)amino]dialkylvinylsilane; (dialkylamino)di(alkoxyalkyl)vinylsilanes such as (dimethylamino)di(methoxymethyl)vinylsilane, (dimethylamino)di(methoxyethyl)vinylsilane, (dimethylamino)di(ethoxymethyl)vinylsilane, (dimethylamino)di(ethoxyethyl)vinylsilane, (diethylamino)di(methoxymethyl)vinylsilane, (diethylamino)di(methoxyethyl)vinylsilane, (diethylamino)di(ethoxymethyl)vinylsilane, and (diethylamino)di(ethoxyethyl)vinylsilane; cyclic aminodialkylvinylsilane compounds such as pyrrolidinodimethylvinylsilane, piperidinodimethylvinylsilane, hexamethyleneiminodimethylvinylsilane, 4,5-dihydroimidazolyldimethylvinylsilane, and morpholinodimethylvinylsilane; and the like.

[0041] In the above general formula (1), X 1 is a hydrocarbylene group, and X 2 , X 3 and X 4Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (1), when one of the groups is a substituted amino group, include (dimethylamino)dimethyl-4-vinylphenylsilane, (dimethylamino)dimethyl-3-vinylphenylsilane, (diethylamino)dimethyl-4-vinylphenylsilane, (diethylamino)dimethyl-3-vinylphenylsilane, (di-n-propylamino)dimethyl-4-vinylphenylsilane, (di-n-propylamino)dimethyl-3-vinylphenylsilane, (di-n-butylamino)dimethyl-4-vinylphenylsilane, (di-n-butylamino)dimethyl- and (dialkylamino)dialkylvinylphenylsilanes such as (dialkylamino)diethyl-3-vinylphenylsilane, (dimethylamino)diethyl-4-vinylphenylsilane, (dimethylamino)diethyl-3-vinylphenylsilane, (diethylamino)diethyl-4-vinylphenylsilane, (diethylamino)diethyl-3-vinylphenylsilane, (di-n-propylamino)diethyl-4-vinylphenylsilane, (di-n-propylamino)diethyl-3-vinylphenylsilane, (di-n-butylamino)diethyl-4-vinylphenylsilane, and (di-n-butylamino)diethyl-3-vinylphenylsilane.

[0042] In the above general formula (1), X 1 is a chemical single bond, and X 2 , X 3 and X 4Specific examples of vinyl compounds containing silicon atom-containing functional groups represented by the above general formula (1) in the case where two of them are substituted amino groups include bis(dialkylamino)alkylvinylsilanes such as bis(dimethylamino)methylvinylsilane, bis(diethylamino)methylvinylsilane, bis(di-n-propylamino)methylvinylsilane, bis(di-n-butylamino)methylvinylsilane, bis(dimethylamino)ethylvinylsilane, bis(diethylamino)ethylvinylsilane, bis(di-n-propylamino)ethylvinylsilane, and bis(di-n-butylamino)ethylvinylsilane; bis[bis(trimethylsilyl)amino]methylvinylsilane, bis[bis(tert-butyldimethylsilyl)amino]methylvinylsilane, bis[bis(trimethylsilyl)amino]ethylvinylsilane, and bis[bis(tert-butyldimethylsilyl)amino]ethylvinylsilane. bis[bis(trialkylsilyl)amino]alkylvinylsilanes; bis(dialkylamino)alkoxyalkylsilanes such as bis(dimethylamino)methoxymethylvinylsilane, bis(dimethylamino)methoxyethylvinylsilane, bis(dimethylamino)ethoxymethylvinylsilane, bis(dimethylamino)ethoxyethylvinylsilane, bis(diethylamino)methoxymethylvinylsilane, bis(diethylamino)methoxyethylvinylsilane, bis(diethylamino)ethoxymethylvinylsilane, and bis(dimethylamino)ethoxyethylvinylsilane; bis(cyclic amino)alkylvinylsilane compounds such as bis(pyrrolidino)methylvinylsilane, bis(piperidino)methylvinylsilane, bis(hexamethyleneimino)methylvinylsilane, bis(4,5-dihydroimidazolyl)methylvinylsilane, and bis(morpholino)methylvinylsilane; and the like.

[0043] In the above general formula (1), X 1 is a hydrocarbylene group, and X 2 , X 3 and X 4Specific examples of vinyl compounds containing silicon atom-containing functional groups represented by the above general formula (1) when two of them are substituted amino groups include bis(dimethylamino)methyl-4-vinylphenylsilane, bis(dimethylamino)methyl-3-vinylphenylsilane, bis(diethylamino)methyl-4-vinylphenylsilane, bis(diethylamino)methyl-3-vinylphenylsilane, bis(di-n-propylamino)methyl-4-vinylphenylsilane, bis(di-n-propylamino)methyl-3-vinylphenylsilane, bis(di-n-butylamino)methyl-4-vinylphenylsilane, bis(di-n-butylamino)methyl- and bis(dialkylamino)alkylvinylphenylsilanes such as bis(dimethylamino)ethyl-3-vinylphenylsilane, bis(dimethylamino)ethyl-4-vinylphenylsilane, bis(dimethylamino)ethyl-3-vinylphenylsilane, bis(diethylamino)ethyl-4-vinylphenylsilane, bis(diethylamino)ethyl-3-vinylphenylsilane, bis(di-n-propylamino)ethyl-4-vinylphenylsilane, bis(di-n-propylamino)ethyl-3-vinylphenylsilane, bis(di-n-butylamino)ethyl-4-vinylphenylsilane, and bis(di-n-butylamino)ethyl-3-vinylphenylsilane.

[0044] In the above general formula (1), X 1 is a chemical single bond, and X 2 , X 3 and X 4 Specific examples of vinyl compounds containing silicon atom-containing functional groups represented by the above general formula (1) when three of the groups are substituted amino groups include tris(dialkylamino)vinylsilanes such as tris(dimethylamino)vinylsilane, tris(diethylamino)vinylsilane, tris(di-n-propylamino)vinylsilane, and tris(di-n-butylamino)vinylsilane.

[0045] In the above general formula (1), X 1 is a hydrocarbylene group, and X 2 , X 3 and X 4Specific examples of vinyl compounds containing silicon atom-containing functional groups represented by the above general formula (1) when three of the groups are substituted amino groups include tris(dialkylamino)vinylphenylsilanes such as tris(dimethylamino)-4-vinylphenylsilane, tris(dimethylamino)-3-vinylphenylsilane, tris(diethylamino)-4-vinylphenylsilane, tris(diethylamino)-3-vinylphenylsilane, tris(di-n-propylamino)-4-vinylphenylsilane, tris(di-n-propylamino)-3-vinylphenylsilane, tris(di-n-butylamino)-4-vinylphenylsilane, and tris(di-n-butylamino)-3-vinylphenylsilane.

[0046] In the above general formula (1), X 1 is a chemical single bond, and X 2 , X 3 and X 4 Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (1), when none of the functional groups is a substituted amino group, include trialkoxyvinylsilanes such as trimethoxyvinylsilane, triethoxyvinylsilane, and tripropoxyvinylsilane; dialkoxyalkylvinylsilanes such as methyldimethoxyvinylsilane and methyldiethoxyvinylsilane; dialkoxyarylvinylsilanes such as di(tert-pentoxy)phenylvinylsilane and di(tert-butoxy)phenylvinylsilane; monoalkoxydialkylvinylsilanes such as dimethylmethoxyvinylsilane; monoalkoxydiarylvinylsilanes such as tert-butoxydiphenylvinylsilane and tert-pentoxydiphenylvinylsilane; monoalkoxyalkylarylvinylsilanes such as tert-butoxymethylphenylvinylsilane and tert-butoxyethylphenylvinylsilane; and substituted alkoxyvinylsilane compounds such as tris(β-methoxyethoxy)vinylsilane.

[0047] Among the compounds represented by the general formula (1), X 1 is preferably a chemical single bond, and X1 is a chemical single bond and X 2 , X 3 and X 4 Among these, compounds in which two are substituted amino groups are more preferred, and X 1 is a chemical single bond and X 2 , X 3 and X 4 Among these, compounds in which two of the groups are dialkylamino groups are particularly preferred.

[0048] Among the compounds represented by the general formula (1), bis(dimethylamino)methylvinylsilane, bis(diethylamino)methylvinylsilane, and bis(di-n-butylamino)methylvinylsilane are preferred, with bis(diethylamino)methylvinylsilane being particularly preferred.

[0049] Furthermore, examples of vinyl compounds containing a functional group capable of interacting with silica other than the compound represented by the general formula (1) above include bis(trialkylsilyl)aminostyrenes such as 4-N,N-bis(trimethylsilyl)aminostyrene and 3-N,N-bis(trimethylsilyl)aminostyrene; and bis(trialkylsilyl)aminoalkylstyrenes such as 4-bis(trimethylsilyl)aminomethylstyrene, 3-bis(trimethylsilyl)aminomethylstyrene, 4-bis(trimethylsilyl)aminoethylstyrene, and 3-bis(trimethylsilyl)aminoethylstyrene.

[0050] When the compound represented by the general formula (1) is used as the vinyl compound containing a functional group capable of interacting with silica, the unit represented by the following general formula (3) is introduced into the elastomer used in the present invention as the unit of the vinyl compound containing a functional group capable of interacting with silica. [ka] In the above general formula (3), X 5 represents a chemical single bond or a hydrocarbylene group, and X 6 , X 7 and X8 each independently represents a hydroxyl group, a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent.

[0051] In the unit represented by the general formula (3), X 5 represents X in the compound represented by the general formula (1). 1 In the unit represented by the general formula (3), X 6 , X 7 and X 8 represents X in the compound represented by the general formula (1). 2 , X 3 and X 4 Therefore, in the unit represented by the general formula (3), X 5 , X 6 , X 7 and X 8 represents X in the compound represented by the general formula (1). 1 , X 2 , X 3 and X 4 In addition, the compound represented by the general formula (1) may be the same as X 2 , X 3 and X 4 In the case where at least one of X is a substituted amino group or a hydrocarbyloxy group, the substituted amino group or the hydrocarbyloxy group can be hydrolyzed in any step and at any timing to form X 2 , X 3 and X 4 At least one of the groups may be a hydroxyl group.

[0052] In the elastomer used in the present invention, the content of vinyl compound units containing a functional group capable of interacting with silica is preferably 0.001 to 10,000% by weight, and more preferably 0.002 to 3,000% by weight, based on 100% by weight of the total amount of all monomer units. By setting the content of vinyl compound units containing a functional group capable of interacting with silica within the above range, the fuel economy of the resulting cross-linked rubber can be further improved while maintaining sufficient processability.

[0053] The elastomer used in the present invention may also contain other monomer units in addition to the conjugated diene monomer units, aromatic vinyl monomer units, and vinyl compound units containing functional groups capable of interacting with silica. Examples of other compounds constituting such other monomer units include linear olefin compounds such as ethylene, propylene, and 1-butene; cyclic olefin compounds such as cyclopentene and 2-norbornene; and non-conjugated diene compounds such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene.

[0054] The bonding pattern of each monomer unit in the elastomer used in the present invention can be various bonding patterns, such as block, tapered, random, etc., but a random bonding pattern is preferred. By using a random bonding pattern, the fuel economy of the resulting elastomer pellets can be further improved.

[0055] The weight average molecular weight (Mw) of the elastomer used in the present invention, as measured by gel permeation chromatography in terms of polystyrene, is preferably 200,000 or more, more preferably 200,000 to 2,000,000, even more preferably 300,000 to 1,000,000, particularly preferably 350,000 to 800,000, and most preferably 400,000 to 600,000.

[0056] The molecular weight distribution of the elastomer used in the present invention, expressed as the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably 1.1 to 5.0, more preferably 1.2 to 3.0, and even more preferably 1.3 to 2.0. By setting the molecular weight distribution (Mw / Mn) of the solution-polymerized aromatic vinyl-conjugated diene copolymer within the above range, the resulting elastomer pellets can be highly balanced in terms of low heat buildup, abrasion resistance, and strength properties.

[0057] The glass transition temperature (Tg) of the elastomer used in the present invention is not particularly limited, but is preferably 0°C or lower, more preferably -20°C or lower, even more preferably -40°C or lower, and particularly preferably -58°C or lower. The lower limit of the glass transition temperature (Tg) is not particularly limited, but is preferably -120°C or higher, more preferably -90°C or higher. By adjusting the glass transition temperature (Tg) of the elastomer within the above range, the obtained cross-linked rubber product can have a higher balance of low heat buildup, abrasion resistance, and strength properties. The method for adjusting the glass transition temperature (Tg) of the elastomer within the above range is not particularly limited, but examples include adjusting the proportion of aromatic vinyl monomer units contained in all monomer units constituting the elastomer and adjusting the vinyl bond content in conjugated diene monomer units.

[0058] The Mooney viscosity (ML1+4,100°C) of the elastomer used in the present invention is preferably 20 to 150, more preferably 30 to 100, still more preferably 40 to 60, and particularly preferably 45 to 54. By adjusting the Mooney viscosity (ML1+4,100°C) of the elastomer to fall within the above range, the productivity of the elastomer can be increased.

[0059] The elastomer used in the present invention preferably has an aromatic vinyl compound block ratio of 20% or less, more preferably 10% or less, and even more preferably 5% or less. 1 The obtained compound was measured by H-NMR. 1The peaks at 6.1 to 7.7 ppm in the H-NMR spectrum are those attributable to aromatic vinyl compounds, and of these, the peaks at 6.1 to 6.88 ppm are those attributable to aromatic vinyl compound blocks. The ratio of the peak area attributable to the aromatic vinyl compound blocks to the peak area attributable to the aromatic vinyl compounds is calculated, and this value is multiplied by 2.5 to express it as a percentage, which is the aromatic vinyl compound block ratio. When the aromatic vinyl compound is styrene, the styrene block ratio is preferably within the above range. By controlling the aromatic vinyl compound block ratio within the above range, the resulting elastomer pellets can be highly balanced in terms of low heat buildup, abrasion resistance, and strength properties. The aromatic vinyl compound block ratio can be controlled by controlling the proportion of the monomers used at the start of polymerization of a monomer containing a conjugated diene compound and an aromatic vinyl compound; controlling the proportion of the aromatic vinyl compound in the monomers to be added and the timing of the addition of the monomers; adjusting the amount of an inert solvent relative to the amount of aromatic vinyl compound used; adjusting the type and amount of a polar compound; controlling the polymerization temperature; or a combination of these methods.

[0060] The elastomer used in the present invention preferably contains a modified group obtained by modifying the end of the copolymer chain with a modifying agent.

[0061] As the modifying group, a nitrogen atom-containing functional group, a silicon atom-containing functional group, an oxygen atom-containing functional group, etc. are preferred from the viewpoint of being able to appropriately increase the affinity with fillers such as silica.

[0062] As the modifier for forming the modifying group, a silicon atom-containing modifier having a silicon atom-containing functional group and a nitrogen atom-containing modifier having a nitrogen atom-containing functional group are preferred, and a silicon atom-containing modifier is more preferred. Examples of the silicon atom-containing modifier include siloxane compounds and hydrocarbyloxysilane compounds. Examples of the nitrogen atom-containing modifier include N,N-disubstituted aminoalkyl(meth)acrylamides such as dimethylaminoethylacrylamide, diethylaminoethylacrylamide, dimethylaminopropylacrylamide, diethylaminopropylacrylamide, dimethylaminobutylacrylamide, diethylaminobutylacrylamide, dimethylaminoethylmethacrylamide, diethylaminoethylmethacrylamide, dimethylaminopropylmethacrylamide, diethylaminopropylmethacrylamide, dimethylaminobutylmethacrylamide, and diethylaminobutylmethacrylamide. imides; amino group-containing alkoxysilane compounds such as [3-(dimethylamino)propyl]trimethoxysilane, [3-(diethylamino)propyl]trimethoxysilane, [3-(dimethylamino)propyl]triethoxysilane, [3-(diethylamino)propyl]triethoxysilane, [3-(ethylmethylamino)propyl]trimethoxysilane, and [3-(ethylmethylamino)propyl]triethoxysilane; and pyrrolidone compounds such as N-phenyl-2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and 1-cyclohexyl-2-pyrrolidone.

[0063] <Elastomer manufacturing method> The method for producing the elastomer used in the present invention is not particularly limited as long as it uses a solution polymerization method, but a method in which monomers are polymerized in an inert solvent using a polymerization initiator is preferred. When the elastomer is to be a copolymer containing aromatic vinyl monomer units and conjugated diene compound monomer units, monomers containing the above-mentioned aromatic vinyl compound and conjugated diene compound can be polymerized. The amounts of the aromatic vinyl compound and conjugated diene compound used may be determined according to the monomer composition of the elastomer to be obtained.

[0064] The inert solvent used in the polymerization is not particularly limited as long as it is one commonly used in solution polymerization and does not inhibit the polymerization reaction. Specific examples of the inert solvent include chain aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; and ether compounds such as tetrahydrofuran and diethyl ether. These inert solvents may be used alone or in combination of two or more. The amount of the inert solvent used is not particularly limited, but is, for example, an amount that results in a monomer concentration of 1 to 50% by weight, preferably 10 to 40% by weight.

[0065] The polymerization initiator is not particularly limited, but specific examples include polymerization initiators using an organic alkali metal compound, an organic alkaline earth metal compound, and a lanthanum series metal compound as a main catalyst. Examples of the organic alkali metal compound include organic monolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, and stilbenelithium; organic polyvalent lithium compounds such as dilithiomethane, 1,4-dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, and 1,3,5-tris(lithiomethyl)benzene; organic sodium compounds such as sodium naphthalene; and organic potassium compounds such as potassium naphthalene. Examples of organic alkaline earth metal compounds include di-n-butylmagnesium, di-n-hexylmagnesium, diethoxycalcium, calcium distearate, di-t-butoxystrontium, diethoxybarium, diisopropoxybarium, diethylmercaptobarium, di-t-butoxybarium, diphenoxybarium, diethylaminobarium, barium distearate, diketylbarium, etc. Examples of polymerization initiators using a lanthanum series metal compound as the main catalyst include polymerization initiators using a lanthanum series metal salt, such as lanthanum, cerium, praseodymium, neodymium, samarium, or gadolinium, as the main catalyst, which is composed of a lanthanum series metal salt formed from a carboxylic acid and a phosphorus-containing organic acid, etc., together with a co-catalyst such as an alkylaluminum compound, an organoaluminum hydride compound, or an organoaluminum halide compound. Among these polymerization initiators, organic monolithium compounds and organic polyvalent lithium compounds are preferably used, organic monolithium compounds are more preferably used, and n-butyllithium is particularly preferably used.

[0066] The organic alkali metal compound may be used as an organic alkali metal amide compound by reacting it with a secondary amine compound such as dibutylamine, dihexylamine, dibenzylamine, pyrrolidine, piperidine, hexamethyleneimine, or heptamethyleneimine. Using an organic alkali metal amide compound as a polymerization initiator allows the introduction of an amine structure derived from the organic alkali metal amide compound at one end of the solution-polymerized aromatic vinyl-conjugated diene copolymer chain, resulting in elastomer pellets with a high level of balance between low heat buildup, abrasion resistance, and strength. These polymerization initiators may be used alone or in combination of two or more.

[0067] The amount of the polymerization initiator used may be determined depending on the molecular weight of the desired elastomer, but is usually in the range of 1 to 50 mmol, preferably 1.5 to 20 mmol, more preferably 2 to 15 mmol per 1000 g of monomer.

[0068] The polymerization temperature is usually in the range of −80 to +150° C., preferably 0 to 100° C., and more preferably 30 to 90° C. As the polymerization mode, any mode such as batchwise or continuous can be adopted, but particularly when the elastomer contains aromatic vinyl monomer units and conjugated diene monomer units, the batchwise mode is preferred since it is easy to control the randomness of bonding between the aromatic vinyl monomer units and the conjugated diene monomer units.

[0069] The polymerization reaction is preferably carried out in the presence of a polar compound. Specifically, it is preferable to use 0.01 to 1.2 mol, more preferably 0.1 to 1.1 mol, and even more preferably 0.1 to 1.0 mol of the polar compound per mol of the polymerization initiator, and to carry out the polymerization in the presence of such a polar compound. This makes it possible to suitably adjust the vinyl bond content in the conjugated diene monomer unit portion contained in the copolymer chain within the above-mentioned range, particularly when the elastomer contains conjugated diene monomer units. Examples of polar compounds that can be used include ether compounds, tertiary amines, phosphine compounds, alkali metal alkoxides, and alkali metal phenoxides. Examples of ether compounds include cyclic ethers such as tetrahydrofuran, tetrahydropyran, and 1,4-dioxane; aliphatic monoethers such as diethyl ether and dibutyl ether; aliphatic diethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and ethylene glycol dibutyl ether; aliphatic triethers such as diethylene glycol diethyl ether and diethylene glycol dibutyl ether; and aromatic ethers such as diphenyl ether, anisole, 1,2-dimethoxybenzene, and 3,4-dimethoxytoluene. These polar compounds may be used alone or in combination of two or more.

[0070] The elastomer may be reacted with a coupling agent to form a coupled polymer chain. Examples of the coupling agent include, but are not limited to, silicon tetrachloride, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, tin tetrachloride, methyltrichlorotin, dimethyldichlorotin, trimethylchlorotin, tetramethoxysilane, methyltrimethoxysilane, dimethoxydimethylsilane, methyltriethoxysilane, ethyltrimethoxysilane, dimethoxydiethylsilane, diethoxydimethylsilane, tetraethoxysilane, ethyltriethoxysilane, diethoxydiethylsilane, bis(trichlorosilyl)methane, 1,2-bis(trichlorosilyl)ethane, 1,3-bis(trichlorosilyl)propane, 1,4-bis(trichlorosilyl)butane, 1,5-bis(trichlorosilyl)pentane, and 1,6-bis(trichlorosilyl)hexane. The coupling agent may be selected depending on the molecular weight distribution curve of the target conjugated diene polymer, but it is preferable to use a coupling agent having three or more functionalities, and it is more preferable to use a coupling agent having four or more functionalities.

[0071] When using a coupling agent, it is preferable to perform a coupling reaction on a portion of the polymer chains having active ends obtained by the above polymerization method to form coupled polymer chains, thereby obtaining a solution containing polymer chains having active ends and coupled polymer chains. In this case, the amount of coupling agent used is not particularly limited, but can be selected depending on the molecular weight distribution curve of the target conjugated diene polymer. It is preferably 0.01 to 0.4 mol, more preferably 0.02 to 0.3 mol, calculated as functional groups of the coupling agent, per mol of polymerization initiator used at the start of polymerization. By adding the coupling agent, the polymer chains having active ends undergo a coupling reaction at the active ends. As a result, the active ends of the polymer chains that have undergone the coupling reaction disappear, becoming free of active ends, while the polymer chains that have not undergone the coupling reaction retain their active ends.

[0072] When the elastomer contains a modifying group introduced into the end of the copolymer chain, it is preferable to react the active end of the copolymer chain obtained by polymerization with the above-mentioned modifying agent. These modifying agents may be used alone or in combination of two or more. The method of reacting the modifying agent is preferably a method of adding the modifying agent to the polymerization solution used in the polymerization, as this is simple and convenient. The amount of the modifying agent used is not particularly limited, but is preferably 0.01 to 10.0 mol, more preferably 0.02 to 5.0 mol, and particularly preferably 0.05 to 2.0 mol, per mol of the active end of the polymer chain having the active end.

[0073] After the polymerization reaction, if necessary, a known polymerization terminator or the like is added to inactivate the reaction system, and then, if desired, an antioxidant such as a phenolic stabilizer, a phosphorus-based stabilizer, or a sulfur-based stabilizer, a crumb-forming agent, or a scale inhibitor is added to the reaction solution, and then the polymerization solvent is separated from the reaction solution by direct drying or steam stripping, etc., to recover the copolymer. Note that, before separating the polymerization solvent from the reaction solution, an extender oil may be mixed with the polymerization solution, and the copolymer may be recovered as an oil-extended elastomer.

[0074] Examples of extender oils used when recovering the copolymer as an oil-extended elastomer include paraffinic, aromatic, and naphthenic petroleum-based softeners, vegetable-based softeners, and fatty acids. When using a petroleum-based softener, it is preferable that the polycyclic aromatic content extracted by the IP346 method (a testing method of The Institute of Petroleum in the UK) is less than 3%. When an extender oil is used, the amount used is preferably 1 to 100 parts by weight, more preferably 2 to 60 parts by weight, and even more preferably 3 to 50 parts by weight per 100 parts by weight of the copolymer.

[0075] <Method of manufacturing elastomer pellets> The elastomer pellets of the present invention are produced by a method comprising a step of hot-cutting an elastomer extruded through a die hole, the step of hot-cutting the elastomer including cooling the elastomer extruded through the die hole with cooling water, wherein the value of parameter A represented by the following general formula (III) is 1.8 or less. A=-X 0.41 -Y 0.36 +Z 0.71 …(III) (In the above general formula (III), X is the weight average molecular weight of the elastomer [10,000], Y is the shear rate of the elastomer in the die hole [1 / sec], and Z is the temperature of the cooling water for the elastomer [°C].)

[0076] Hot cutting is a method in which a heated elastomer is extruded through a die and cut by a cutter provided opposite the die. Examples of hot cutting include air hot cutting, in which the elastomer extruded from the die is cut in the air and cooled with cooling water, and underwater hot cutting, in which the elastomer extruded from the die is cut while being cooled in water. From the viewpoint of production capacity, underwater hot cutting is preferred.

[0077] FIG. 1 is a schematic cross-sectional view showing the underwater hot cutting method according to this embodiment.

[0078] The process of hot-cutting an elastomer involves the following steps. First, the elastomer produced by the above method is fed into an extruder 10, as shown in FIG. 1. The elastomer may be fed in a state containing water or an inert solvent, allowing it to be dried within the extruder 10. Alternatively, the elastomer may be fed to the extruder 10 in the form of a dried bale or the like. The elastomer is then heated within the extruder 10 and continuously extruded by a screw 11 and a gear pump 12 through a die hole 21 of a die 20 into cooling water flowing through a pipe 40. The elastomer is then cooled by the cooling water and hot-cut underwater by a cutter 30 to form multiple elastomer pieces 50. The elastomer pieces 50 are transported by the cooling water and dehydrated in a centrifugal dehydrator (not shown) to be recovered as elastomer pellets. The dehydration method is not particularly limited, and known methods can be used.

[0079] The extruder 10 has twin screws 11, but is not particularly limited thereto and may have a single screw. In addition, in this embodiment, a gear pump 12 is provided between the outlet of the extruder 10 and the die 20, but is not particularly limited thereto and may not have a gear pump.

[0080] The extrusion flow rate of the elastomer by the extruder 10 is preferably 450 to 3,000,000 mm 3 / sec, more preferably 500 to 3000 mm 3 The barrel temperature of the extruder 10 is preferably 150 to 200°C.

[0081] The shear rate of the elastomer in the die hole 21 (die hole shear rate) is preferably 1 to 100 / sec, more preferably 20 to 50 / sec. By setting the die hole shear rate within the above range, the generation of froth can be further suppressed. The die hole shear rate can be calculated by the following formula (IV), and can be controlled by the conditions of the extruder 10. Shear rate in the die hole = (256 × extrusion flow rate [mm3 / sec] / number of die holes [pcs] / (15 × π × die hole diameter [mm 3 ]) …(IV)

[0082] The diameter of the die hole 21 is preferably 1 to 20 mm, more preferably 2 to 15 mm. The length of the die hole 21 (the length over which the elastomer passes through the die 20) is preferably 10 to 150 mm, more preferably 20 to 100 mm. The number of die holes 21 is preferably 1 to 300, more preferably 2 to 10.

[0083] Although not particularly limited, the cutter 30 is composed of a rotating body provided with a plurality of blades and is provided opposite the die hole 21 of the die 20. From the viewpoint of improving the accuracy of hot cutting, it is preferable that the cutter 30 be in sliding contact with the die 20 so as to be able to cut the elastomer immediately after it has been extruded through the die hole 21, or that the cutter 30 and the die 20 be not in contact with each other and the distance between them be 0.01 to 0.3 mm. The number of blades on the cutter 30 is preferably 1 to 8, and more preferably 1 to 3. The rotation speed of the cutter 30 is preferably 100 to 1500 rpm, and more preferably 500 to 1100 rpm.

[0084] Cooling water is supplied by a pump (not shown) and flows through piping 40, cooling the elastomer extruded from the holes of die 21 and transporting cut elastomer pieces 50. The temperature of the cooling water is preferably less than 40°C, and more preferably 1 to 24°C. By keeping the temperature of the cooling water within the above range, the generation of froth can be further suppressed. The flow rate of the cooling water is preferably 0.001 to 0.1 m 3 / sec, and more preferably 0.01 to 0.05 m 3 / sec.

[0085] The temperature of the elastomer during hot cutting is preferably 100 to 250°C, and more preferably 130 to 200°C.

[0086] The length L of the pellet produced by hot cutting can be calculated by the following formula (V) when the diameter of the pellet is equal to the diameter of the die hole 21. The length L of the pellet is preferably 0.3 to 20 mm, and more preferably 0.5 to 5 mm. Pellet length L=Qt / πr 2 (V) In the above formula (V), Q is the extrusion flow rate [mm 3 / sec], t is the cutting time [sec] defined as the reciprocal of the product of the underwater cutting rotation speed and the number of blades, and r is the radius of the die hole [mm].

[0087] In the method for producing elastomer pellets of the present invention, the value of parameter A represented by the above formula (III) is 1.8 or less. The value of parameter A is 1.8 or less, preferably 1.0 or less, more preferably 0.0 or less, even more preferably -1.5 or less, and particularly preferably -3.0 or less. The lower limit of parameter A is not particularly limited, but is usually -10 or more. To achieve a value of parameter A of 1.8 or less, the shear rate in the die hole and the temperature of the cooling water may be appropriately adjusted according to the weight-average molecular weight of the elastomer used. By achieving a value of parameter A of 1.8 or less, the amount of froth generated per kg of produced elastomer pellets [g / kg] can be reduced.

[0088] As described above, the inventors have conducted extensive research into the problem of froth generation in the production of elastomer pellets by hot cutting, and have newly discovered that froth generation can be effectively suppressed by adjusting the shear rate in the die hole and the temperature of the cooling water according to the weight average molecular weight of the elastomer.

[0089] In particular, when producing elastomer pellets using an elastomer with a low glass transition temperature, specifically an elastomer with a glass transition temperature of −40° C. or lower, froth tends to occur more easily than when using an elastomer with a glass transition temperature higher than −40° C. The present inventors have newly discovered that by adjusting the shear rate in the die hole and the temperature of the cooling water according to the weight-average molecular weight of the elastomer and setting the value of parameter A to 1.8 or less, it is possible to effectively suppress the occurrence of froth in the production of elastomer pellets by hot cutting, even when an elastomer with a glass transition temperature of −40° C. or lower is used.

[0090] According to the present invention, the generation of froth during the production of elastomer pellets can be effectively suppressed, and as a result, high-quality elastomer pellets can be produced with high productivity. [Example]

[0091] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0092] <Content of styrene units, vinyl bond amount> The content (wt%) of styrene units in the elastomer and the amount (mol%) of vinyl bonds in the conjugated diene monomer units are determined according to JIS K6239-1:2017. 1 It was determined by H-NMR.

[0093] <Styrene block ratio> The styrene block ratio as the aromatic vinyl monomer block ratio in the elastomer was calculated by the following method using deuterated chloroform as a solvent. 1 The obtained compound was measured by H-NMR. 1 The peaks at 6.1 to 7.7 ppm in the H-NMR spectrum were determined to be those derived from styrene, and of these, the peaks at 6.1 to 6.88 ppm were determined to be those derived from styrene blocks. The ratio of the peak area derived from styrene blocks to the peak area derived from styrene was calculated, and the value was multiplied by 2.5 to express it as a percentage, which was taken as the styrene block ratio. Reference: Sardelis, K. Michels, HJ Allen, G. Polymer, 1984, 25, 1011

[0094] <Mooney viscosity> The Mooney viscosity (ML1+4) of the elastomer was measured in accordance with JIS K 6300-1:2013 under the following conditions. Test temperature: 100℃ or 125℃ Rotor type: L-type Testing equipment used: Shimadzu Mooney Viscometer SMV-300J manufactured by Shimadzu Corporation

[0095] <Glass transition temperature (Tg)> The glass transition temperature (Tg) of the elastomer was measured in a helium atmosphere (gas flow rate: 20.0 mL / min) using a differential scanning calorimeter (manufactured by PerkinElmer, product name "DSC8500") according to JIS K6240:2011. The peak top temperature of the differential curve of the obtained DSC curve was determined as the glass transition temperature (Tg).

[0096] <Weight average molecular weight> The weight average molecular weight of the elastomer was determined based on a chart obtained by gel permeation chromatography (GPC) based on the molecular weight converted to polystyrene. The specific measurement conditions for gel permeation chromatography were as follows: Measuring instrument: High-performance liquid chromatograph (Tosoh Corporation, product name "HLC-8320") Column: Two polystyrene columns manufactured by Tosoh Corporation, trade name "TSKgel SuperHM-H", were connected in series. Detector: Refractive index (RI) Eluent: 0.9 vol % of 2-(ethylamino)ethanol (Fujifilm Wako Chemical Co., Ltd., special grade, stabilizer-free) was added to tetrahydrofuran (Kanto Chemical Co., Ltd., special grade). Column temperature: 40℃ Flow rate: 0.6mL / min Sample solution concentration: 1.0 mg / mL Sample solution solvent: Tetrahydrofuran (Kanto Chemical Co., Ltd., special grade, stabilizer-free) Sample solution injection volume: 5 μL Molecular weight calculation method: Ten types of standard polystyrenes with known molecular weights were analyzed by GPC, and the common logarithm of the molecular weight was plotted against the retention time of each standard polystyrene. A fifth-order polynomial approximation equation was calculated from the obtained plot to create a calibration curve. A conjugated diene polymer was analyzed by GPC, and the polystyrene-equivalent molecular weight of the conjugated diene polymer was calculated from the obtained retention time and the calibration curve. Standard polystyrene: F-700, F-288, F-128, F-80, F-40, F-20, F-4, F-2, A-5000, A-2500 (all manufactured by Tosoh Corporation, product name "TSKgel Standard Polystyrene")

[0097] [Manufacturing Example 1] (SBR A polymerization) An autoclave equipped with a stirrer was charged under a nitrogen atmosphere with 470.5 parts of industrial hexane (Sumitomo Chemical Co., Ltd., trade name: Hexane (general product), density 0.68 g / mL), 42.7 parts of 1,3-butadiene, 7.3 parts of styrene, 0.329 parts of tetrahydrofuran, and 0.078 parts of ethylene glycol dibutyl ether. A small amount of n-butyllithium was added to the autoclave as a scavenger to detoxify impurities that could deactivate the polymerization. Then, 0.029 parts of n-butyllithium was added as a polymerization initiator, and polymerization was initiated at 40°C. At 0 minutes after the start of polymerization, 47.7 parts of 1,3-butadiene were added continuously over 115 minutes, and 2.3 parts of styrene were added continuously over 80 minutes. Immediately after the completion of the continuous addition of 1,3-butadiene, 0.252 parts of ethylene glycol dibutyl ether was added, followed by stirring for 30 minutes. The maximum temperature during the polymerization reaction was 70°C. After confirming that the polymerization conversion rate was in the range of 95% to 100%, 0.139 parts of [3-(diethylamino)propyl]trimethoxysilane was added and the mixture was allowed to react for 45 minutes. Next, 0.057 parts of normal butyllithium was added and the mixture was allowed to react for 15 minutes. Then, as a polymerization terminator, methanol was added in an amount equivalent to twice the molar amount of the total amount of lithium in the autoclave to obtain a solution containing a conjugated diene-based polymer. Then, 0.80 parts of 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumilizer GM) and 0.40 parts of pentaerythrityl tetrakis(3-laurylthiopropionate) (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumilizer TP-D) were added as antioxidants to the solution, and the mixture was mixed and stirred until homogeneous to obtain a polymer solution. The resulting polymer solution was then spread on a tray and allowed to stand at room temperature for 12 hours, and then dried in a vacuum dryer set at 65°C for 6.5 hours to remove the solvent, thereby obtaining SBR A.

[0098] [Manufacturing Example 2] (SBR B polymerization) An autoclave equipped with a stirrer was charged with 444.4 parts of industrial hexane (Sumitomo Chemical Co., Ltd., trade name: Hexane (general product), density 0.68 g / mL), 34.5 parts of 1,3-butadiene, 15.5 parts of styrene, 0.311 parts of tetrahydrofuran, and 0.051 parts of ethylene glycol dibutyl ether under a nitrogen atmosphere. A small amount of n-butyllithium was added to the autoclave as a scavenger to detoxify impurities that could deactivate the polymerization. Then, 0.027 parts of n-butyllithium were added as a polymerization initiator, and polymerization was initiated at 30°C. 0 minutes after the start of polymerization, 35.5 parts of 1,3-butadiene were added continuously over 110 minutes, and 14.5 parts of styrene were added continuously over 100 minutes. After the continuous addition of 1,3-butadiene was completed, the mixture was stirred for an additional 10 minutes. The maximum temperature during the polymerization reaction was 70°C. After confirming that the polymerization conversion rate was in the range of 95% to 100%, 0.013 parts of N-(3-dimethylaminopropyl)acrylamide was added and the mixture was allowed to react for 20 minutes. Next, 0.133 parts of 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate was added and the mixture was allowed to react for 20 minutes. Then, as a polymerization terminator, methanol was added in an amount equivalent to twice the molar amount of the total amount of lithium in the autoclave to obtain a solution containing a conjugated diene-based polymer. Then, 0.50 parts of 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate and 0.25 parts of pentaerythrityl tetrakis(3-laurylthiopropionate) were added to the solution as antioxidants. Furthermore, 17.6 parts of oil (manufactured by JXTG Nippon Oil & Energy Corporation, trade name "Process NC140") were added as an extender oil, and the mixture was mixed and stirred until homogeneous, obtaining a polymer solution. The resulting polymer solution was then spread on a tray and allowed to stand at room temperature for 12 hours, and then dried in a vacuum dryer set at 65°C for 6.5 hours to remove the solvent, thereby obtaining SBR B.

[0099] [Manufacturing Example 3] (SBR C polymerization) An autoclave equipped with a stirrer was charged under a nitrogen atmosphere with 695.4 parts of industrial hexane (Sumitomo Chemical Co., Ltd., trade name: Hexane (general product), density 0.68 g / mL), 104.7 parts of cyclohexane, 35.0 parts of 1,3-butadiene, 15.0 parts of styrene, 0.544 parts of tetrahydrofuran, and 0.025 parts of ethylene glycol dibutyl ether. A small amount of n-butyllithium was added to the autoclave as a scavenger to detoxify impurities that could deactivate the polymerization. Then, 0.0036 parts of n-butyllithium were added as a polymerization initiator, and polymerization was initiated at 45°C. Ten minutes after the start of polymerization, 50.0 parts of 1,3-butadiene were continuously added over 170 minutes. 110 minutes after the start of polymerization, 0.022 parts of n-butyllithium were added. After the continuous addition of 1,3-butadiene was completed, the mixture was stirred for an additional 35 minutes. The maximum temperature during the polymerization reaction was 75°C. After confirming that the polymerization conversion rate was in the range of 95% to 100%, 0.0028 parts of silicon tetrachloride was added and the reaction was allowed to proceed for 10 minutes. Thereafter, 0.101 parts of [3-(diethylamino)propyl]trimethoxysilane was added and the reaction was allowed to proceed for 20 minutes. Next, 0.049 parts of normal butyllithium was added and the reaction was allowed to proceed for 15 minutes. Furthermore, 0.025 parts of ethylene glycol dibutyl ether was added and the mixture was stirred for 15 minutes. Thereafter, methanol was added as a polymerization terminator in an amount equivalent to twice the molar amount of the total amount of lithium in the autoclave to obtain a solution containing a conjugated diene-based polymer. To this solution, 0.89 parts of 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate and 0.445 parts of pentaerythrityl tetrakis(3-laurylthiopropionate) were added as antioxidants, and the mixture was stirred until homogeneous to obtain a polymer solution. The resulting polymer solution was then spread on a tray and left to stand at room temperature for 12 hours, and then dried in a vacuum dryer set at 65°C for 6.5 hours to remove the solvent, yielding SBR C.

[0100] The styrene unit content, vinyl bond amount, styrene block ratio, Mooney viscosity, glass transition temperature (Tg), and weight average molecular weight (Mw) were measured for SBRs A to C obtained in Production Examples 1 to 3. The results are shown in Table 1.

[0101] [Table 1]

[0102] [Examples 1 to 5 and Comparative Examples 1 and 2] SBRs A to C according to Examples 1 to 5 and Comparative Examples 1 and 2 were subjected to hot cutting by an underwater cutting method using an intermeshing co-rotating twin-screw extruder (TEX-30α, manufactured by The Japan Steel Works, Ltd.) as shown in FIG. The extruder used had a screw outer diameter of 33 mm and an L / D (L: effective screw length, D: screw outer diameter) of 77, and a gear pump was installed between the tip of the screw and the die (hole diameter 2.8 mm, 8 holes). The operating conditions were a screw rotation speed of 32 rpm, a barrel temperature of 150°C, a cutter installed in a position where it would come into contact with and slide against the die, three cutter blades for hot cutting, and a cutter blade rotation speed of 550 rpm. The extrusion flow rate and cooling water temperature were changed within the ranges shown in Table 2. The shear rate in the die holes was calculated according to the following formula. The calculation results are shown in Table 2. Shear rate in the die holes = (256 × extrusion flow rate [mm 3 / sec] / number of holes [pieces] / (15 × π × hole diameter [mm 3 ]). The hot-cut SBR was dispersed in circulating cooling water and transported to a centrifugal dehydrator with a screen mesh diameter of 1 mm. Most of the SBR was separated from the water in the centrifugal dehydrator and recovered as pellets. Meanwhile, the SBR that was not separated from the water in the centrifugal dehydrator was recovered as froth using a filter installed downstream of the centrifugal dehydrator. The pellets and froth recovered during the 30-minute operation were dried in a vacuum dryer set at 60°C for 24 hours to remove moisture, and each was weighed. The froth weight [g] relative to the pellet weight [kg] was defined as the froth generation rate [g / kg]. The results are summarized in Table 2.

[0103] [Table 2]

[0104] As shown in Table 2, in Examples 1 to 5, in which elastomer pellets were produced under conditions where the value of parameter A was 1.8 or less, the amount of froth generated was kept low. On the other hand, in Comparative Examples 1 and 2, in which the value of parameter A was more than 1.8, the amount of froth generated was increased. [Explanation of symbols]

[0105] 10...Extruder 11...Screw 12...Gear pump 20...Die 21...Die hole 30...Cutter 40...Piping 50...Elastomer piece

Claims

1. A method for producing elastomer pellets, comprising: hot-cutting the elastomer extruded through the die hole of the die; The step of hot-cutting the elastomer includes cooling the elastomer extruded through the die holes with cooling water, and the value of parameter A represented by the following general formula (I) is 1.8 or less. A=-X ０．４１ -Y ０．３６ +Z ０．７１ …(I) (In the above general formula (I), X is the weight average molecular weight of the elastomer [10,000], Y is the shear rate of the elastomer in the die hole [1 / sec], and Z is the temperature of the cooling water for the elastomer [°C].)

2. 2. The method for producing elastomer pellets according to claim 1, wherein the hot cutting is underwater hot cutting.

3. 3. The method for producing elastomer pellets according to claim 1, wherein the temperature of the cooling water is lower than 40°C.

4. 3. The method for producing elastomer pellets according to claim 1, wherein the weight average molecular weight (Mw) of the elastomer is 200,000 or more.

5. 3. The method for producing elastomer pellets according to claim 1, wherein the elastomer is an elastomer containing a conjugated diene compound.

6. 3. The method for producing elastomer pellets according to claim 1, wherein the elastomer is an elastomer containing an aromatic vinyl compound.

7. 3. The method for producing elastomer pellets according to claim 1, wherein the elastomer is a random copolymer containing aromatic vinyl compound monomer units and conjugated diene compound monomer units.

8. 7. The method for producing elastomer pellets according to claim 6, wherein the aromatic vinyl compound has a block ratio of 20% or less.

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