JP2019157069A - Rubber composition - Google Patents

Abstract

To improve a strength after crosslinking when formed into a rubber molded product in a rubber composition including a ricinoleic acid copolymer as a plasticizer.SOLUTION: The rubber composition includes 100 pts.mass of (X) a crosslinkable rubber, 1 to 50 pts.mass of (A) a copolymer of [α] ricinoleic acid and/or a derivative thereof, [β] a dicarboxylic acid and [γ] a diol and 0.01 to 10 pts.mass of (C) a crosslinking agent, in which the copolymer (A) satisfies at least requirements as given below: the requirement that the content of a structural unit derived from the ricinoleic acid and/or the derivative thereof [α] is 10 mol% to less than 100 mol% based on the total of the structural unit derived from the ricinoleic acid and/or the derivative thereof [α], a structural unit derived from the dicarboxylic acid [β] and a structural unit derived from the diol [γ]; the requirement that the weight average molecular weight Mw is 10,000 to 500,000; and the requirement that the ratio (Mw/Mn) of the weight average molecular weight Mw to the number average molecular weight Mn is 2 to 6.SELECTED DRAWING: None

Description

  The present invention relates to a rubber composition containing a ricinoleic acid copolymer.

  Since crosslinked rubber has excellent rubber elasticity and heat resistance, it is widely used as tires for automobiles, anti-vibration rubbers, and various sealing materials. Synthetic rubbers such as natural rubber, styrene butadiene rubber, butadiene rubber, and ethylene propylene rubber are used as the raw rubber, and the annual consumption exceeds 20 million tons.

  In recent years, from the viewpoint of global warming issues, renewable energy, resource recycling, resource circulation, etc., material development based on natural product-derived raw materials replacing petroleum raw materials has become active. Among them, various bio-based polymers such as polylactic acid have been developed.

  Here, in recent years, a ricinoleic acid (12-hydroxy-cis-9-octadecenoic acid) -based polymer has attracted attention as a bio-based polymer exhibiting general rubber-like physical properties. Ricinoleic acid is a substance obtained by a method such as hydrolysis of castor oil. It is known that ricinoleic acid polymers exhibit rubber-like physical properties due to crosslinking.

  Various attempts have been made on ricinoleic acid polymers. For example, Patent Document 1 discloses a method of performing polycondensation of ricinoleic acid using a supported enzyme in which lipase or the like is supported on a carrier such as synthetic zeolite as a catalyst. Patent Documents 2 and 3 disclose attempts to use a ricinoleic acid polymer as an elastomer component.

International Publication 2008/029805 Pamphlet Japanese Patent No. 5373435 Japanese Patent No. 5398708

  When producing a molded article of rubber, rubber is often used in the form of a rubber composition to which various components are added. In this rubber composition, the fluidity and molding processability of rubber during molding are improved by blending mineral oil such as paraffin oil as a plasticizer. However, depending on the blending of rubber and plasticizer, a phenomenon (bleed) may occur in which the plasticizer inside the molded body oozes out after the rubber composition is formed into a molded body. This bleed not only causes stickiness on the surface of the molded body, but may also lead to deterioration of the quality of the molded body. Here, the present inventors have obtained the knowledge that the problem of bleeding in the rubber molded body has been improved by replacing a part of the plasticizer blended in the rubber composition with a specific ricinoleic acid copolymer. . As a result of further investigation by the present inventors, when a part of the plasticizer to be blended in the rubber composition is replaced with a specific ricinoleic acid copolymer, the strength after cross-linking when formed into a molded body is not necessarily sufficiently increased. It turns out that there may not be. The present inventors consider that this is because the ricinoleic acid copolymer often contains many low molecular weight components, so that the degree of crosslinking is not sufficiently increased when viewed as a whole copolymer. .

  Accordingly, the object of the present invention is to solve such problems in a rubber composition containing a ricinoleic acid copolymer as a plasticizer, and to improve the strength after crosslinking when a rubber molded body is obtained.

  As a result of intensive studies in such a situation, the present inventors have removed a low molecular weight component from a ricinoleic acid copolymer when replacing a part of the plasticizer to be blended with the rubber composition with the ricinoleic acid copolymer. The present inventors have found that the above problems can be improved and have completed the present invention.

That is, the present invention relates to the following [1] to [4].
[1]
100 parts by weight of crosslinkable rubber (X),
1 to 50 parts by mass of a copolymer (A) of ricinoleic acid and / or a derivative thereof [α], a dicarboxylic acid [β], and a diol [γ] satisfying at least the following requirements (1) to (3) When,
A rubber composition comprising 0.01 to 10 parts by mass of a crosslinking agent (C).
(1) The content of the structural unit derived from ricinoleic acid and / or its derivative [α] is a structural unit derived from the aforementioned ricinoleic acid and / or its derivative [α], and a structural unit derived from dicarboxylic acid [β]. , 10 mol% or more and less than 100 mol% with respect to the total with the structural unit derived from diol [γ];
(2) The weight average molecular weight Mw measured by GPC (gel permeation chromatography) of the copolymer (A) is 10,000 or more and 500,000 or less;
(3) The ratio (Mw / Mn) of the weight average molecular weight Mw and the number average molecular weight Mn of the copolymer (A) is 2 or more and 6 or less.

[2]
In the above [1], the copolymer (A) contains at least one selected from the group consisting of a dicarboxylic acid [β1] having 2 to 12 carbon atoms and a diol [γ1] component having 2 to 12 carbon atoms. The rubber composition as described.

[3]
The copolymer (A) is
(I) 10 to 80 mol% of structural units derived from ricinoleic acid and / or its derivative [α],
(II) 10 to 45 mol% of structural units derived from dicarboxylic acid [β1] having 2 to 12 carbon atoms and (III) 10 to 45 mol% of structural units derived from diol [γ1] having 2 to 12 carbons.
(However, the total of structural units (I), (II), and (III) is 100 mol%)
The rubber composition according to the above [1] or [2].

[4]
The crosslinkable rubber (X) is natural rubber (NR), isoprene rubber (IR), butyl rubber (IIR), butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), Any one of [1] to [3] above, which is at least one selected from the group consisting of chloroprene rubber (CR), ethylene-propylene rubber (EPR), and ethylene-propylene-diene rubber (EPDM) A rubber composition according to any one of the above.

  According to the present invention, when the ricinoleic acid copolymer is included in the rubber composition, the low molecular weight component of the ricinoleic acid polymer is removed to improve the bleeding problem when the rubber molded body is obtained. It is possible to provide a crosslinked product exhibiting excellent mechanical properties.

(Rubber composition)
The rubber composition according to the present invention is
100 parts by weight of crosslinkable rubber (X),
1 to 50 parts by mass of a copolymer (A) of ricinoleic acid and / or a derivative thereof [α], a dicarboxylic acid [β], and a diol [γ],
Including 0.01 to 10 parts by mass of a crosslinking agent (C).

Here, the copolymer (A) satisfies at least the following requirements (1) to (3):
(1) The content of the structural unit derived from ricinoleic acid and / or its derivative [α] is a structural unit derived from the aforementioned ricinoleic acid and / or its derivative [α], and a structural unit derived from dicarboxylic acid [β]. , 10 mol% or more and less than 100 mol% with respect to the total with the structural unit derived from diol [γ];
(2) The weight average molecular weight Mw measured by GPC (gel permeation chromatography) of the copolymer (A) is 10,000 or more and 500,000 or less;
(3) The ratio (Mw / Mn) of the weight average molecular weight Mw and the number average molecular weight Mn of the copolymer (A) is 2 or more and 6 or less.

In addition, in this specification, the mass part of each component with respect to 100 mass parts of rubber (X) may be called phr.
Hereinafter, the rubber composition of the present invention and each component constituting the rubber composition of the present invention will be described in detail.

<Crosslinkable rubber (X)>
The crosslinkable rubber (X) constituting the rubber composition of the present invention may be a known rubber, and examples thereof include conjugated diene rubbers and olefin copolymer rubbers.

  Examples of the conjugated diene rubber include natural rubber (NR), isoprene rubber (IR), isoprene rubber such as butyl rubber (isobutene / isoprene rubber (IIR)), butadiene rubber (BR), styrene-butadiene rubber (SBR), Examples include acrylonitrile-butadiene rubber (NBR) and chloroprene rubber (CR).

  Examples of olefin copolymer rubbers include ethylene / α-olefin copolymer rubbers such as ethylene-propylene random copolymer (EPR), and ethylene / α-olefins such as ethylene-propylene-diene rubber (EPDM). Examples thereof include olefin / polyene copolymers.

The crosslinkable rubber (X) can be used alone or in combination of two or more.
In the present specification, the crosslinkable rubber (X) may be simply referred to as “rubber (X)”.

<Copolymer (A)>
The copolymer (A) constituting the rubber composition of the present invention is a copolymer of ricinoleic acid and / or its derivative [α], dicarboxylic acid [β], and diol [γ]. That is, the copolymer (A) includes a structural unit derived from ricinoleic acid and / or its derivative [α], a structural unit derived from dicarboxylic acid [β], and a structural unit derived from diol [γ].
Hereinafter, the copolymer (A) will be described.

(Ricinolic acid and / or its derivative [α])
In the present invention, ricinoleic acid and / or its derivative [α] is used as one of the components constituting the copolymer (A). That is, the copolymer (A) used in the present invention contains a structural unit derived from ricinoleic acid and its derivative [α] (hereinafter sometimes referred to as “structural unit [α ′]”). Become. Here, the structural unit [α ′] in the present invention is specifically a structural unit represented by the following formula (1) or the following formula (2).

リシノール酸の誘導体として、エステル化、またはエステル交換反応の条件下で、上記式（１）で表される構造単位または上記式（２）で表される構造単位を与える化合物が挙げられ、その例として、リシノール酸のエステル体、並びに、リシノール酸を水添して得られる１２−ヒドロキシステアリン酸または１２−ヒドロキシステアリン酸のエステル体等を挙げることができる。リシノール酸および／またはその誘導体［α］の中では、イオウ系化合物による架橋が可能という観点からリシノール酸またはリシノール酸のエステル体が好ましい。

Examples of derivatives of ricinoleic acid include compounds that give a structural unit represented by the above formula (1) or a structural unit represented by the above formula (2) under the conditions of esterification or transesterification, and examples thereof. Examples thereof include ricinoleic acid ester, 12-hydroxystearic acid or 12-hydroxystearic acid ester obtained by hydrogenating ricinoleic acid, and the like. Among ricinoleic acid and / or its derivative [α], ricinoleic acid or an ester of ricinoleic acid is preferable from the viewpoint that crosslinking with a sulfur compound is possible.

  These compounds described above as ricinoleic acid and / or its derivative [α] can be polymerized relatively easily by esterification or transesterification in the presence of a catalyst described later.

  Ricinoleic acid or its derivative [α] can be used singly or in combination of two or more. Here, in the present invention, in obtaining the copolymer (A), ricinoleic acid or its derivative [α] is used in combination with dicarboxylic acid [β] and diol [γ] described later. At this time, it is also possible to adjust the terminal structure and molecular weight of the copolymer (A) obtained by the ratio of using dicarboxylic acid [β] and diol [γ].

  In the present invention, when the total molar amount of terminal hydroxyl groups contained in each raw material used is (OH) and the total molar amount of terminal carboxyl groups is (COOH), the molar ratio (hereinafter referred to as OH / COOH ratio). The preferred range is from 1.0 to 5.0, more preferably from 1.0 to 3.0. When the OH / COOH ratio is 1.0 or more and 5.0 or less, sufficient hydroxyl group ends are formed in the low-molecular oligomer prepared in the esterification or transesterification reaction described later, and the reaction during polycondensation described later Tend to improve. On the other hand, when the OH / COOH ratio exceeds 5.0, a part of the excess raw material diol [γ] contributes to the decomposition of the resin, and the reactivity during polycondensation may be lowered.

(Dicarboxylic acid [β])
In the present invention, dicarboxylic acid [β] is used as another component constituting the copolymer (A). That is, the copolymer (A) used in the present invention contains a structural unit derived from dicarboxylic acid [β] (hereinafter sometimes referred to as “structural unit [β ′]”). Here, the structural unit [β ′] in the present invention is specifically a structural unit having a structure in which —OH is excluded from two carboxyl groups contained in the dicarboxylic acid [β].

As the dicarboxylic acid [β], a known dicarboxylic acid compound can be used without limitation, and an aliphatic dicarboxylic acid is preferable.
Examples of the aliphatic dicarboxylic acid include linear or branched aliphatic such as succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, etc. Dicarboxylic acids; and lower alkyl esters of these aliphatic dicarboxylic acids.

  Among these, a C2-C12 dicarboxylic acid is preferable. That is, in one preferred embodiment of the present invention, the dicarboxylic acid [β] is a C 2-12 dicarboxylic acid [β1]. Among these, a dicarboxylic acid having 6 to 10 carbon atoms, particularly preferably 9 to 10 carbon atoms, is more preferable. If the carbon number of the dicarboxylic acid becomes too large, the polycondensation reactivity may decrease. Examples of the dicarboxylic acid having 9 to 10 carbon atoms include sebacic acid and azelaic acid having a structure relatively similar to ricinoleic acid. Among them, sebacic acid is particularly preferable.

  These dicarboxylic acids [β] can be used singly or in combination of two or more. Moreover, it is also possible to use as an ester body with the above-mentioned ricinoleic acid, or a low condensation compound.

(Diol [γ])
In the present invention, diol [γ] is used as another component constituting the copolymer (A). That is, the copolymer (A) used in the present invention contains a structural unit derived from diol [γ] (hereinafter sometimes referred to as “structural unit [γ ′]”). Here, the structural unit [γ ′] in the present invention is specifically a structural unit having a structure in which —H is excluded from two hydroxyl groups contained in the diol [γ].

As the diol [γ], a known diol can be used without limitation, and an alkylene diol can be preferably used.
Specific examples of the alkylene diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8- Octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2- Aliphatic diols such as butyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, diethylene glycol and triethylene glycol, 2,2-bis [ 4 '-(2 "-hydroxyethoxy) phenyl] propane, 4,4'-bis (2" -hydroxyethoxy) phenyl sulfide, Fragrances such as 4'-bis (2 "-hydroxyethoxy) phenylsulfone, 9,9-bis [4 '-(2" -hydroxyethoxy) phenyl] fluorene, 1,4-bis (2'-hydroxyethoxy) benzene An ethylene oxide adduct of an aromatic dihydroxy compound, tricyclo [5.2.1.0 (2,6)] decanedimethanol, 1,4-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanedimethanol, Mention may be made of alicyclic diols such as 1,3-cyclohexanedimethanol, 2,2-bis (4′-hydroxycyclohexyl) propane (hydrogenated bisphenol A).

These diols [γ] are preferably primary alcohols. If the diol [γ] is a secondary or higher alcohol, the polycondensation reactivity may decrease.
Among these, C2-C12 diol is preferable. A diol having 2 to 6 carbon atoms, particularly preferably 2 to 4 carbon atoms is more preferable. If the diol has too many carbon atoms, the polycondensation reactivity may decrease. Specifically, aliphatic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol are preferable. More preferred are ethylene glycol, 1,3-propanediol and 1,4-butanediol having a relatively small number of carbon atoms. When the biodegradability of the polycondensate is expected, a preferred diol [γ] is 1,4-butanediol available from natural esters.

  These diols [γ] can be used alone or in combination of two or more. Moreover, it is also possible to use as an ester body with the above-mentioned ricinoleic acid, or a low condensation compound.

(Other copolymer components)
The copolymer (A) used in the present invention is a copolymer of the above-mentioned ricinoleic acid and / or its derivative [α], dicarboxylic acid [β], and diol [γ]. In other words, the copolymer (A) used in the present invention contains the structural unit [α ′], the structural unit [β ′], and the structural unit [γ ′] described above. For example, in one preferred embodiment of the present invention, the copolymer (A) comprises only the above-described structural unit [α ′], structural unit [β ′], and structural unit [γ ′].

  However, the copolymer (A) used in the present invention is not limited to such an embodiment, and the above-described ricinoleic acid and / or its derivative [α], dicarboxylic acid [β], and diol [γ ] Other copolymer components (hereinafter, “other copolymer components”) may be included within a range not impairing the object of the present invention. In other words, the copolymer (A) used in the present invention is a structural unit that does not fall under any of the structural unit [α ′], structural unit [β ′], and structural unit [γ ′] described above (hereinafter, “Other structural units”) may be included.

Here, as a specific example of “other copolymerization components”,
Hydroxycarboxylic acids such as glycolic acid, 4-hydroxybenzoic acid, 4- (2′-hydroxyethoxy) benzoic acid;
Trifunctional or more polyfunctional components such as a polycarboxylic acid having 3 or more carboxyl groups and a polyol having 3 or more hydroxyl groups can be mentioned.

  Here, specific examples of the polycarboxylic acid having 3 or more carboxyl groups include trimellitic acid, trimesic acid, pyromellitic acid, and naphthalenetetracarboxylic acid, and specific examples of the polyol having 3 or more hydroxyl groups. Examples include trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, and the like.

(Configuration of copolymer (A))
In the rubber composition of the present invention, the copolymer (A) satisfies at least the following requirements (1) to (3).

  Requirement (1): The content of the structural unit derived from ricinoleic acid and / or its derivative [α] is a structural unit derived from the aforementioned ricinoleic acid and / or its derivative [α] and the structure derived from dicarboxylic acid [β] It is 10 mol% or more and less than 100 mol% with respect to the total of the unit and the structural unit derived from diol [γ].

  That is, the copolymer (A) used in the present invention has a structure when the total of the structural unit [α ′], the structural unit [β ′], and the structural unit [γ ′] described above is 100 mol%. The unit [α ′] is contained in an amount of 10 mol% or more and less than 100 mol%.

  Here, looking at the lower limit of the content, from the viewpoint of ensuring low temperature physical properties of the vulcanized rubber, the structural unit [α ′] is 10 mol% or more, preferably 30 mol% or more, more preferably 50 mol% or more. It is. On the other hand, when looking at the upper limit, the structural unit [α ′] is less than 100 mol%, preferably 80 mol% or less, in the present invention, from the viewpoint of securing sufficient processability and suppressing the hardness reduction of the vulcanized rubber. More preferably, it is 70 mol% or less.

  On the other hand, the content ratio of the structural unit derived from the dicarboxylic acid [β] (that is, the structural unit [β ′] described above) is preferably more than 0 mol% and 45 mol% or less. 10 mol% or more is preferable and the range of the lower limit side of the said content rate has more preferable 15 mol% or more. The upper limit range is preferably 35 mol% or less, and more preferably 25 mol% or less.

The content ratio of the structural unit derived from the diol [γ] (that is, the structural unit [γ ′] described above) is preferably more than 0 mol% and 45 mol% or less. 10 mol% or more is preferable and the range of the lower limit side of the said content rate has more preferable 15 mol% or more. The upper limit range is preferably 35 mol% or less, and more preferably 25 mol% or less.
In addition, when the copolymer (A) further includes the above-mentioned “other structural unit” in addition to the structural unit [α ′], the structural unit [β ′], and the structural unit [γ ′], The ratio of the “other structural unit” is more than 0 mol% and 5 mol with respect to the total of 100 mol% of the structural unit [α ′], the structural unit [β ′], and the structural unit [γ ′] described above. % Or less is preferable.

Here, in a preferred embodiment of the present invention, the copolymer (A) is:
(I) 10 to 80 mol% of structural units derived from ricinoleic acid and / or its derivative [α],
(II) 10 to 45 mol% of structural units derived from dicarboxylic acid [β1] having 2 to 12 carbon atoms and (III) 10 to 45 mol% of structural units derived from diol [γ1] having 2 to 12 carbons.
(However, the total of structural units (I), (II), and (III) is 100 mol%)
including.

Requirement (2): The copolymer (A) has a weight average molecular weight Mw measured by GPC (gel permeation chromatography) of 10,000 to 500,000.
When the copolymer (A) used in the present invention has a weight average molecular weight Mw in such a range, it is preferable from the viewpoint of balance between workability and strength after vulcanization.
Requirement (3): The ratio (Mw / Mn) of the weight average molecular weight Mw and the number average molecular weight Mn of the copolymer (A) is 2 or more and 6 or less.

When a crosslinked product is obtained from a composition containing a copolymer of ricinoleic acid and / or a derivative thereof [α], a dicarboxylic acid [β], and a diol [γ], a low molecular weight component contained in the copolymer If the ratio is large, the mechanical strength may be lowered when a crosslinked product is obtained. On the other hand, if the proportion of the low molecular weight component contained in the copolymer is reduced to some extent, the mechanical strength is reduced when the crosslinked product is formed, and a somewhat high mechanical strength tends to be obtained. Here, a small proportion of the low molecular weight component contained in the copolymer means that the molecular weight distribution of the molecules contained in the copolymer is narrow, that is, the ratio of the weight average molecular weight Mw to the number average molecular weight Mn. It means that (Mw / Mn) is small. Therefore, in the present invention, since a crosslinked product having a somewhat high mechanical strength can be obtained, a copolymer having a small Mw / Mn to some extent is employed as the copolymer (A). In the present invention, when viewed from the upper limit of Mw / Mn of the copolymer (A), Mw / Mn is 6 or less, preferably 5.5 or less.
The number average molecular weight Mn is a value measured by GPC (gel permeation chromatography) as with the weight average molecular weight Mw.

  On the other hand, the low molecular weight component contained in the copolymer of ricinoleic acid and / or its derivative [α], dicarboxylic acid [β], and diol [γ] gives plasticity to the composition containing this copolymer. There is another aspect. From this, when the content of the low molecular weight component in this copolymer is very small, the processability when processing the composition containing this copolymer as a rubber composition, particularly the processability when roll processing, May decrease. From this point of view, it is preferable that the copolymer contains an appropriate amount of a low molecular weight component within a range in which the mechanical strength of the crosslinked product can be maintained to some extent. Based on this, in the present invention, the lower limit of Mw / Mn of the copolymer (A) is defined as 2. However, such a problem of deterioration in workability can be avoided to some extent by separately adding a softener or using a processing method other than roll processing.

The copolymer (A) used in the present invention may be a single type of copolymer or a mixture of two or more types of copolymers.
Here, when the copolymer (A) used in the present invention is a mixture composed of two or more kinds of copolymers, each of the copolymers constituting such a copolymer (A), It is a copolymer of the ricinoleic acid and / or its derivative [α], the dicarboxylic acid [β], and the diol [γ]. In this case, as long as the copolymer (A) as a whole satisfies the above requirements (1) to (3), each of the copolymers constituting the copolymer (A) itself is not limited to the above requirements ( It is not necessary to satisfy 1) to (3). Moreover, each copolymer which comprises a copolymer (A) may be the same, or may mutually differ. For example, in each copolymer constituting the copolymer (A), one or more of the structural unit [α ′], the structural unit [β ′], and the structural unit [γ ′] may be different from each other. . Each of the copolymers constituting the copolymer (A) has a ratio of the structural unit [α ′], the structural unit [β ′], the structural unit [γ ′], and the optional “other structural unit”. They may be different from each other.

(Production method of copolymer (A))
The copolymer (A) used in the present invention is a step of subjecting the ricinoleic acid and / or its derivative [α], the dicarboxylic acid [β], and the diol [γ] to an ester polymerization reaction (hereinafter, “Ester polymerization step”). By this ester polymerization step, a copolymer containing the structural unit [α ′], the structural unit [β ′], and the structural unit [γ ′] (hereinafter referred to as “copolymer (A ′)”) is obtained. Will be. Here, when this ester polymerization reaction is carried out in the presence of the hydroxycarboxylic acid described above in the above “other copolymerization component” and a polyfunctional component having three or more functional groups, the “other structural unit” is also included. A copolymer (A ′) can be obtained.
Here, as long as the Mw / Mn satisfies the requirement (3), this copolymer (A ′) may be used as it is as the copolymer (A). However, in many cases, the copolymer (A ′) is led to the copolymer (A) through a step of removing a low molecular weight component, as will be described later.

In the production method of the present invention, a conventionally known method such as direct esterification or transesterification can be applied as a method for performing the “ester polymerization step”.
In the direct esterification method, the above-mentioned ricinoleic acid and / or its derivative [α], the dicarboxylic acid [β], the diol [γ], and the optional “other copolymerization component” are directly condensed by a conventional method. By making it, a copolymer (A'-1) can be obtained as a copolymer (A '). For example,
The ricinoleic acid and / or its derivative [α],
The dicarboxylic acid [β],
The diol [γ] is heated under pressure to obtain a low molecular weight condensate while removing the generated condensed water from the reaction system, and then in the presence of a polycondensation catalyst such as a titanium compound, a germanium compound, or an antimony compound. The pressure inside the reaction system is reduced to distill off the diol. Thereby, a high molecular weight polyester resin can be produced as the copolymer (A). In this example, the case of reacting the ricinoleic acid and / or its derivative [α], the dicarboxylic acid [β] and the diol [γ] has been described, but the case where the above “other copolymerization components” coexist. The same can be done.

In the transesterification method, a corresponding dialkyl ester of the dicarboxylic acid [β] may be used as a starting material instead of the dicarboxylic acid [β]. In this case, the corresponding dialkyl ester is employed as the dicarboxylic acid [β], the ricinoleic acid and / or its derivative [α], the diol [γ], and the optional “other copolymerization component”. In addition, the copolymer (A′-2) can be obtained as the copolymer (A ′) by direct condensation polymerization using a conventional method. At this time, the ricinoleic acid and / or its derivative [α] and / or the compound having a carboxyl group among the various compounds described in the above “other copolymerization components” are also used in the form of the corresponding alkyl ester. May be. For example,
The ricinoleic acid and / or its derivative [α],
A dialkyl ester of the dicarboxylic acid [β],
The diol [γ] is heated at normal pressure to form a low molecular weight condensate while removing the generated alkyl alcohol from the reaction system, and then in the presence of a polycondensation catalyst such as a titanium compound, a germanium compound, or an antimony compound. The diol is distilled out of the system by reducing the pressure in the reaction system. Thereby, a high molecular weight polyester resin can be manufactured.

  Here, in one preferable aspect of the present invention, the polycondensation catalyst includes, as the first metal compound, at least one compound selected from the group consisting of a titanium compound, an antimony compound, and a germanium compound, Preferably, a titanium compound is included.

  Specific examples of the titanium compound include tetrabutyl titanate, tetra-iso-propyl titanate, and acetyl tri-iso-propyl titanate. Examples of the antimony compound include antimony acetate, and examples of the germanium compound include germanium dioxide. The titanium compound, the antimony compound, and the germanium compound may be two or more types of titanium compounds, two or more types of antimony compounds, and two or more types of germanium compounds, respectively.

  The usage-amount of a titanium compound is 1,000-5,000 mass ppm in metal conversion (titanium conversion) with respect to the copolymer (A'-1) or (A'-2) manufactured. The usage-amount of an antimony compound is 100-30,000 mass ppm in metal conversion (antimony conversion) with respect to the copolymer (A'-1) or (A'-2) manufactured. The usage-amount of a germanium compound is 100-30,000 mass ppm in metal conversion (germanium conversion) with respect to the copolymer (A'-1) or (A'-2) manufactured. Moreover, you may use combining 2 or more types among a titanium compound, an antimony compound, and a germanium compound. In this case, the total amount of the titanium compound, the antimony compound and the germanium compound is preferably 1,500 to 60,000 wtppm as the total of the respective metal conversions with respect to the polyester to be produced.

  In addition to the first metal compound, the polycondensation catalyst further includes a metal compound selected from the group consisting of Group 2 and Group 8 to Group 12 elements of the periodic table as the second metal compound. It may be included. Specific examples of the second metal compound include compounds such as calcium, magnesium, cobalt, and zinc, and are preferably compounds of Group 2 elements of the periodic table called alkaline earth metals. More preferred are calcium compounds and magnesium compounds. As calcium compounds, for example, calcium acetate, magnesium compounds, for example, magnesium acetate, cobalt compounds, for example, cobalt acetate, and zinc compounds, for example, zinc acetate can be mentioned. When the first metal compound and the second metal compound are used in combination, the total number of moles (X) of metal atoms derived from the second metal compound and the titanium atom and germanium derived from the first metal compound The ratio to the total number of moles (Y) of atoms and antimony atoms (hereinafter sometimes referred to as X / Y ratio) is usually 0.05 to 0.5.

  Polymerization of the raw material containing the ricinoleic acid and / or its derivative [α] can be performed under known conditions. Specifically, as polymerization in the previous stage, ricinoleic acid and / or its derivative [α], dicarboxylic acid [β], diol [γ], and the like, and the plurality of metal compounds as a catalyst are charged into a reactor. Water or alcohol generated while heating is removed to promote esterification or transesterification to synthesize a low molecular weight oligomer. Thereafter, as the subsequent polymerization, the polycondensation reaction proceeds under reduced pressure, and the generated alcohol compound is removed to increase the molecular weight. A specific preferred temperature range when synthesizing a low molecular weight oligomer by an esterification reaction or a transesterification reaction, which is the preceding polymerization, is 200 to 250 ° C, more preferably 210 to 230 ° C. The specific preferred temperature range of the polycondensation reaction, which is the latter polymerization, is 220 to 250 ° C., more preferably 220 to 230 ° C., and the pressure in the reaction apparatus is preferably 400 Pa (3 Torr) or less, more preferably 133 Pa (1 Torr) or less. It is obvious that a lower pressure in the reactor is preferable, but considering the production cost, the lower limit of the pressure is preferably 0.05 Torr, more preferably 0.1 Torr.

  In the above example, the case where the ricinoleic acid and / or its derivative [α] and the dialkyl ester of the dicarboxylic acid [β] are reacted with the diol [γ] has been described. This can be done in the same way when the coexists.

The esterification reaction in the direct esterification method and transesterification method proceeds even without a catalyst, but it is preferable to use a polycondensation catalyst as exemplified above.
In both the direct esterification method and the transesterification production method, while maintaining the reaction system in a uniform liquid state, while raising the reaction system so that the reaction temperature does not fall below the melting point of the oligomer and polyester produced It is preferable to proceed the reaction. If it is necessary to further increase the molecular weight (weight average molecular weight), the copolymer polyester resin obtained by melt polymerization can be subjected to solid phase polymerization to increase the molecular weight.

  The copolymer (A ′) used in the present invention can also be produced by an ester polymerization reaction with lipase. In this method, the above ricinoleic acid and / or its derivative [α], dicarboxylic acid [β], diol [γ], and optional “other copolymerization component” are subjected to condensation polymerization in the presence of lipase. The copolymer (A′-3) can be obtained as the copolymer (A ′). As the lipase, an immobilized lipase derived from Burkholderia cepacia (for example, lipase PS-C Amano II (trade name), PS-D Amano I (trade name) and the like sold by Wako Pure Chemical Industries, Ltd.) is preferable. In this case, since the lipase is hardly deactivated even at a high temperature, the reaction temperature can be increased to 90 ° C. The reaction conditions are preferably a batch method using a reactor equipped with a stirrer under bulk conditions. The reaction time is usually 4 to 7 days, although it varies depending on conditions such as catalyst concentration and polymerization temperature.

  Further, the ester polymerization reaction is a reversible reaction, and it is preferable to sequentially remove the generated alcohol and water in order to advance an efficient polymerization reaction. Specifically, maintaining the pressure state in the reaction system in a reduced pressure state, or performing a synthesis reaction after placing a hygroscopic agent such as synthetic zeolite (for example, molecular sieve 4A) in the reaction system in a non-contact manner. Is mentioned. By carrying out the polymerization reaction under such conditions, the polymerization reaction can be progressed simply and easily, and the copolymer (A ′) can be synthesized efficiently.

  In the present invention, the amount of ricinoleic acid and / or its derivative [α], dicarboxylic acid [β], diol [γ], and optional “other copolymerization component” charged in each ester polymerization reaction is adjusted. The ratio can be appropriately adjusted according to the contents of the structural units [α ′], [β ′], [γ ′] and “other structural units” to be achieved in the copolymer (A).

In the copolymer (A ′) obtained through the “ester polymerization step”, the double bond contained in the structural unit [α ′] may be left as it is. Hydrogenation may be carried out on some or all of the double bonds contained in the structural unit [α ′] by performing a hydrogenation reaction using a known appropriate method. For example, first, a copolymer (A0 ′) containing a structural unit represented by the above formula (1) as the structural unit [α ′] in the copolymer (A ′) is prepared by an ester polymerization reaction, Thereafter, the copolymer (A0 ′) may be partially or completely hydrogenated to lead to the corresponding hydrogenated copolymer (A ″).
Any of the copolymer (A ′) and the hydrogenated copolymer (A ″) can be used as they are as the copolymer (A) as long as Mw / Mn satisfies the requirement (3). Also good. However, as a method for carrying out the “ester polymerization step”, in any case where the direct esterification method, the transesterification method and the ester polymerization reaction by lipase described above are carried out, the copolymer (A ′ ) Contains a lot of low molecular weight substances, and the molecular weight distribution tends to be wide. Similarly, in the case of the hydrogenated copolymer (A ″), the molecular weight distribution tends to be wide. Therefore, when such a copolymer is used as a crosslinked product as it is, the degree of crosslinking is usually not sufficiently increased, and as a result, sufficient mechanical strength tends to be not obtained.

In the present invention, in order to improve the mechanical strength of the crosslinked product, in the usual case, the copolymer (A) production method includes a copolymer obtained by the ester polymerization reaction in addition to the ester polymerization reaction step. A step of removing low molecular weight components that may be included in the coalescence will be further included. Here, the step of removing the low molecular weight component specifically includes the copolymer (A ′), the hydrogenated copolymer (A ″), or the copolymer (A ′) and the above. This is performed as a step of removing low molecular weight components that may be contained in the mixture with the hydrogenated copolymer (A ″).
A specific method for removing the low molecular weight component contained in the copolymer (A ′) and / or the hydrogenated copolymer (A ″) is such that the Mw / Mn of the obtained copolymer is the above requirement ( Although it will not specifically limit as long as 3) can be satisfy | filled, the following method can be mentioned as the example.

For example, the copolymer (A ′) and / or the hydrogenated copolymer (A ″) is dissolved in a suitable good solvent, and then a poor solvent is added to precipitate the polymer component, thereby reducing the low molecular component. The low molecular weight component can be removed by removing the solvent in which is dissolved. As another method, the copolymer (A ′) and / or the hydrogenated copolymer (A ″) is dissolved in an appropriate good solvent and dialyzed with a dialysis membrane having a defined pore size. Thereafter, the low molecular weight component can be fractionated and removed by evaporating the solvent.
Here, examples of the good solvent include xylene and chloroform. Moreover, methanol etc. are mentioned as an example of the said poor solvent.
The molecular weight distribution of the ricinoleic acid copolymer from which low molecular weight components have been removed by the above method is preferably 2 or more and 6 or less, and more preferably 2 or more and 5.5 or less. When the molecular weight distribution is larger than 6, the mechanical strength tends to decrease due to the influence of low molecular weight components.

(Role of the copolymer (A) in the rubber composition of the present invention)
In the rubber composition of the present invention, the copolymer (A) functions as a reactive plasticizer. Here, the reactive plasticizer refers to a substance that functions as a plasticizer during processing and that polymerizes or undergoes an addition reaction with rubber molecules after vulcanization.

  The rubber composition of the present invention is provided with flexibility and processability by including the copolymer (A). Moreover, when the rubber composition is crosslinked, excellent mechanical properties can be obtained. In addition, the plasticizer hardly oozes out from the crosslinked product obtained by the crosslinking. This is presumably because the copolymer (A) is polymerized or undergoes an addition reaction to rubber molecules after crosslinking. Further, in the rubber composition of the present invention, a copolymer having a low low molecular weight component is used as the copolymer (A). Therefore, a ricinoleic acid copolymer having a high low molecular weight component is used instead of the copolymer (A). Compared with the case of using, there is a tendency that a decrease in the crosslinking rate during crosslinking is reduced.

  Content of the copolymer (A) in the rubber composition of this invention is 1-50 mass parts with respect to 100 mass parts of rubber | gum (X), Preferably it is 5-30 mass parts, More preferably, it is 5-5 mass parts. 20 parts by mass.

<Crosslinking agent (C)>
The crosslinking agent (C) constituting the rubber composition of the present invention is not particularly limited as long as it can crosslink the rubber (X) and the copolymer (A), and is a sulfur compound or a peroxide crosslinking agent. For example, various materials commonly used in the field of rubber may be used.

  In the present invention, as a suitable crosslinking agent (C), a sulfur-based compound (C1) may be mentioned. By crosslinking the ricinoleic acid (co) polymer rubber composition with the sulfur-based compound (C1), compared with the case where a peroxide-based cross-linking agent such as dicumyl peroxide is used, the cross-linked rubber has a low temperature equivalent to that. While providing the characteristics, it is possible to impart exceptional flexibility and mechanical characteristics.

  Examples of the sulfur compound (C1) include sulfur, sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, and selenium dithiocarbamate. Among these, sulfur and tetramethyl thiuram disulfide are preferable.

  On the other hand, depending on the type of rubber (X), a peroxide-based crosslinking agent (C2) can also be used as the crosslinking agent (C). The peroxide-based crosslinking agent (C2) can be a suitable crosslinking agent (C) particularly when an olefin copolymer rubber such as EPDM is employed as the rubber (X).

As the peroxide-based crosslinking agent (C2),
1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 2,2-bis (t-butylperoxy) octane, Peroxyketals such as 1,1-bis (t-butylperoxy) cyclododecane, and
Di-t-butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, α, α′-bis (t-butylperoxy-m-isopropyl) benzene, 2,5-dimethyl-2,5-di (T-butylperoxy) hexyne-3, t-butylperoxy-2-ethylhexanoate, t-butylperoxy-3,5,5-trimethylhexanoate, 2,5-dimethyl-2,5 -Dialkyl peroxides such as di (benzoylperoxy) hexane and the like.

Content of the crosslinking agent (C) in the rubber composition of this invention is 0.01-10 mass parts with respect to 100 mass parts of rubber | gum (X), Preferably it is 0.01-5 mass parts.
Here, when a sulfur type compound (C1) is used as a crosslinking agent (C), it is preferable that the content is 0.01-5 mass parts with respect to 100 mass parts of said rubber | gum (X).
On the other hand, when the peroxide crosslinking agent (C2) is used as the crosslinking agent (C), the content thereof is preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the rubber (X). .

<Other ingredients>
The rubber composition of the present invention contains the above-described rubber (X), copolymer (A), and cross-linking agent (C), and may further contain other components according to the application.

  As other components that can be included in the rubber composition of the present invention, various additives such as a plasticizer, a reinforcing material, a vulcanization accelerator, a co-crosslinking agent, a vulcanization aid, a processing aid, an antiaging agent, and an activator are added. Agents. Moreover, a well-known foaming agent, foaming adjuvant, a coloring agent, a dispersing agent, a flame retardant etc. can be used as another component as needed.

Plasticizer The rubber composition of the present invention comprises a plasticizer other than the copolymer (A), specifically, a known plasticizer generally used as a softener in the rubber field, depending on its use. Further, it may be included.

  Specific examples of such plasticizers include petroleum-based softeners such as process oil, lubricating oil, paraffin oil, liquid paraffin, petroleum asphalt, and petroleum jelly; coal-tar softeners such as coal tar and coal tar pitch; Fatty oil-based softeners such as castor oil, linseed oil, rapeseed oil, soybean oil and coconut oil; waxes such as beeswax, carnauba wax and lanolin; ricinoleic acid, palmitic acid, stearic acid, barium stearate, calcium stearate, And fatty acids such as zinc laurate or salts thereof; naphthenic acid, pine oil, and rosin or derivatives thereof; synthetic polymer substances such as terpene resin, petroleum resin, atactic polypropylene, and coumarone indene resin; dioctyl phthalate, dioctyl adipate , And Dioctylse Ester softeners such sebacate and the like; microcrystalline wax, liquid polybutadiene, modified liquid polybutadiene, liquid Thiokol, hydrocarbon-based synthetic lubricating oil, tall oil, and the like sub (factice), and the like. Of these, petroleum softeners are preferred. Among the petroleum-based softeners, petroleum-based process oils are preferable, and paraffin-based process oils, naphthenic process oils, aroma-based process oils, and the like are more preferable.

  Here, the content of the plasticizer can be appropriately selected depending on the application, and is usually 200 parts by mass at maximum, preferably 150 parts by mass, more preferably 130 parts by mass with respect to 100 parts by mass of rubber (X). Is desirable.

Reinforcing Material The rubber composition of the present invention may further contain a reinforcing material in order to enhance mechanical properties such as tensile strength, tear strength, and abrasion resistance when the crosslinked composition is formed.

  Examples of the reinforcing material include carbon black, silica, activated calcium carbonate, light calcium carbonate, heavy calcium carbonate, talc, silicic acid, and clay. These reinforcing materials can be used alone or in combination of two or more.

  Among these, from the viewpoint of uniform dispersibility in the rubber matrix, excellent reinforcing properties, and versatility (cost), the reinforcing material is preferably at least one selected from the group consisting of carbon black and silica.

  The type of carbon black is not particularly limited, and known types commonly used in the rubber industry, such as furnace black (classified according to ASTM D 1765), channel black, thermal black, acetylene black, etc., may be used depending on the purpose of use. .

Here, the carbon black may be used after being surface-treated with a silane coupling agent or the like.
On the other hand, the type of silica is not particularly limited, and examples thereof include known dry silica and wet silica that are usually used in the rubber industry according to the purpose of use.

Moreover, as heavy calcium carbonate, commercially available "Whiteon SB" (brand name; Shiroishi Calcium Co., Ltd.) etc. can be used.
Although the kind and compounding quantity of a reinforcing material can be suitably selected according to the use, the compounding quantity of a reinforcing material is 300 mass parts at maximum normally with respect to 100 mass parts of rubber | gum (X), Preferably it is 200 mass parts at maximum.

Vulcanization accelerator The rubber composition according to the present invention may further contain a vulcanization accelerator in addition to the rubber (X), the copolymer (A) and the crosslinking agent (C).

  Here, in the rubber composition according to the present invention, the content of the vulcanization accelerator is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 100 parts by mass with respect to 100 parts by mass of the rubber (X). 10 parts by mass. By including a vulcanization accelerator in the rubber composition with such a content, the rubber composition has excellent crosslinking properties, and the generation of bloom in the resulting crosslinked rubber can be further reduced.

  Specific examples of the vulcanization accelerator include N-cyclohexyl-2-benzothiazole sulfenamide (for example, “Sunseller CM” (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)), N-oxydiethylene-2- Benzothiazole sulfenamide, N, N′-diisopropyl-2-benzothiazole sulfenamide, 2-mercaptobenzothiazole (for example, “Sunseller M” (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)), 2- (4-morpholinodithio) penzothiazole (for example, “Noxeller MDB-P” (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)), 2- (2,4-dinitrophenyl) mercaptobenzothiazole, 2- ( 2,6-diethyl-4-morpholinothio) benzothiazole, dibenzothiazyl disulfide and other thiazoles; Guanidines such as phenylguanidine, triphenylguanidine and diorthotolylguanidine; acetaldehyde-aniline condensates, butyraldehyde-aniline condensates, aldehyde amines; imidazolines such as 2-mercaptoimidazolines; thioureas such as diethylthiourea and dibutylthiourea Tetramethylthiuram monosulfide, tetramethylthiuram disulfide (eg, “Sunceller TT” (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)), etc .; zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, dibutyldithiocarbamine Zinc oxides (for example, “Suncellor BZ” (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)), dithioate salts such as tellurium diethyldithiocarbamate; ethylenethiourea (for example, "Sunseller 22-C" (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.), thiourea series such as N, N'-diethylthiourea; xanthate series such as zinc dibutylxatogenate; other zinc white (for example, " META-Z102 "(trade name; zinc oxide such as Inoue Lime Industry Co., Ltd.).

Co-crosslinking agent When the peroxide-based crosslinking agent (C2) is used as the crosslinking agent (C), the rubber composition according to the present invention includes the rubber (X), the copolymer (A), and the In addition to the crosslinking agent (C), an appropriate co-crosslinking agent can be further included as necessary for the purpose of improving physical properties and vulcanization rate.

  Examples of co-crosslinking agents include polyethylene glycol dimethacrylate (PEGDM) such as Blemmer PDE-100 (trade name, manufactured by Nippon Oil & Fats Co., Ltd.), triallyl such as dialkyl phthalate (DAP), and Thaik (trade name, manufactured by Nippon Kasei Co., Ltd.). Tetraallyl cyanurate (TAC) such as isocyanurate (TAIC), Tac (trade name, manufactured by Musashino Chemical Laboratory), tetrahydrofurfuryl methacrylate (THFMA), such as acrylate ester THF (trade name, manufactured by Mitsubishi Rayon Co., Ltd.) , Ethylene dimethacrylate (EDMA), Acryester BD (trade name, manufactured by Mitsubishi Rayon Co., Ltd.) such as Sunester EG (trade name, manufactured by Sanshin Chemical Industry Co., Ltd.) and Acryester ED (trade name, manufactured by Mitsubishi Rayon Co., Ltd.) 1,3-butylene dimethacrylate (BD A), trimethylol trimethacrylate such as Sunester TMPMA (trade name, manufactured by Sanshin Chemical Industry Co., Ltd.), Acryester TMP (trade name, manufactured by Mitsubishi Rayon Co., Ltd.) and Hi-Cross M (trade name, manufactured by Seiko Chemical Co., Ltd.) Examples include propane (TMMPMA).

The addition amount of the co-crosslinking agent is suitably about 1 to 10 parts by mass with respect to 100 parts by mass of the rubber (X).
In the rubber composition of this embodiment, vulcanization aids such as methacrylic acid esters and triallyl isocyanurates (TAIC) such as Taik (Nippon Kasei Co., Ltd.) are used during vulcanization using a peroxide-based crosslinking agent. You may add further as an agent.

Vulcanization aid The rubber composition according to the present invention may further contain a vulcanization aid in addition to the rubber (X), the copolymer (A) and the crosslinking agent (C).

  Specific examples of the vulcanization aid include magnesium oxide and zinc white (for example, zinc oxide such as “META-Z102” (trade name; manufactured by Inoue Lime Industry Co., Ltd.)). The content is usually 1 to 20 parts by mass with respect to 100 parts by mass of rubber (X).

Processing aid The rubber composition according to the present invention may further contain a processing aid in addition to the rubber (X), the copolymer (A) and the crosslinking agent (C).

  As the processing aid, a compound used for processing ordinary rubber can be used. Specifically, higher fatty acids such as ricinoleic acid, stearic acid, palmitic acid and lauric acid; salts of higher fatty acids such as barium stearate, zinc stearate and calcium stearate; ricinoleic acid, stearic acid, palmitic acid and lauric acid And higher fatty acid esters.

  Such a processing aid is usually used in a proportion of 10 parts by mass or less, preferably 5 parts by mass or less, based on 100 parts by mass of rubber (X). It is desirable to determine.

Anti-aging Agent The rubber product produced from the rubber composition according to the present invention may further contain an anti-aging agent in order to prolong the product life. Examples of the anti-aging agent include conventionally known anti-aging agents such as amine-based anti-aging agents, phenol-based anti-aging agents, and sulfur-based anti-aging agents.

  Specifically, aromatic secondary amine type antioxidants such as phenylbutylamine and N, N-di-2-naphthyl-p-phenylenediamine, dibutylhydroxytoluene, tetrakis- [methylene-3- (3 ′, 5'-di-t-butyl-4'-hydroxyphenyl) propionate] phenolic antioxidants such as methane; bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-t-butylphenyl Thioether-based anti-aging agents such as sulfide; dithiocarbamate-based anti-aging agents such as nickel dibutyldithiocarbamate; 2-mercaptobenzoylimidazole, zinc salt of 2-mercaptobenzimidazole, dilaurylthiodipropionate, distearylthiodipro Sulfur-based anti-aging agents such as pionate are listed.

  These anti-aging agents can be used alone or in combination of two or more, and the content of such anti-aging agents is usually 0.3 to 100 parts by mass of rubber (X). It is 10 mass parts, Preferably it is 0.5-7.0 mass parts, More preferably, it is 0.7-5.0 mass parts. When the content of the antioxidant is within the above range, inhibition of vulcanization at the time of crosslinking of the rubber composition can be reduced, and the occurrence of bloom in the resulting rubber crosslinked body can be reduced.

Activator The rubber composition of the present invention may contain one or more activators as required. Specific examples of the activator include di-n-butylamine, dicyclohexylamine, monoethanolamine, “Acting B” (trade name; manufactured by Yoshitake Pharmaceutical Co., Ltd.), and “Acting SL” (trade name; Yoshitsugu Pharmaceutical Co., Ltd.). Amines such as diethylene glycol, polyethylene glycol, lecithin, triallyl trimellitate, zinc compounds of aliphatic and aromatic carboxylic acids (eg “Struktol activator 73”, “Struktol IB 531” and “Struktol FA541” ( Amine-based activators such as trade name; manufactured by Schill &Seilacher); zinc peroxide preparations such as “ZEONET ZP” (trade name; manufactured by ZEON Corporation); octadecyltrimethylammonium bromide, synthetic hydrotalsa Door, special quaternary ammonium compounds (for example, "Arquad 2HF" (trade name; manufactured by Lion Akzo Co., Ltd.)), and the like.
Content of an activator is 0.2-10 mass parts with respect to 100 mass parts of rubber | gum (X), Preferably it is 0.3-5 mass parts, More preferably, it is 0.5-4 mass parts.

<Method for producing rubber composition>
The rubber composition of the present invention comprises a general rubber from the above-mentioned predetermined parts by mass of rubber (X), copolymer (A) and cross-linking agent (C) and the above-mentioned “other components” blended as necessary. It can be prepared by a method similar to the preparation method of the blend.

  For example, rubber (X), copolymer (A), cross-linking agent (C), and other ingredients blended as necessary using internal mixers and rolls such as Banbury mixers, kneaders, and intermixes. After kneading at a temperature of 80 to 170 ° C. for 3 to 10 minutes, a vulcanization accelerator or a vulcanization aid is further added as necessary, and a roll temperature such as an open roll or a kneader is used. It can be prepared by kneading at 40-80 ° C. for 5-30 minutes and then dispensing. In this way, a rubber composition (blended rubber) usually in the form of a ribbon or sheet is obtained.

<Use of rubber composition>
The rubber composition of the present invention can be used as a raw material for a crosslinked rubber.
When a rubber cross-linked body is obtained using the rubber composition of the present invention as a raw material, the rubber cross-linked body is usually formed by using the above rubber composition as an extrusion molding machine, calendar roll, press, injection molding machine, transfer molding machine, hot air, glass. Pre-formed into a desired shape by various forming methods such as bead fluidized bed, UHF (ultra-high frequency electromagnetic wave), steam, heating tank such as LCM (hot molten salt tank), etc. It can be obtained by crosslinking by introducing it into the inside and heat-treating it. For this heat treatment, a heating tank in a heating form such as HAV (hot air), PCM (glass bead fluidized bed), UHF (ultra-high frequency electromagnetic wave), steam, LCM (hot molten salt tank) can be used. Moreover, as temperature at the time of heating (crosslinking), it is generally 140-300 degreeC, Preferably it is 150-270 degreeC, More preferably, it is 150-250 degreeC, 0.5 to 30 minutes, Preferably 0.5 to Heat for 20 minutes, more preferably 0.5-15 minutes. In molding and crosslinking, a mold may be used or a mold may not be used. When a mold is not used, the rubber composition is usually molded and crosslinked continuously.

And the rubber crosslinked body of the present invention is formed by crosslinking the rubber composition. In addition, the rubber composition is excellent in molding processability, and the obtained rubber cross-linked product is very useful as a rubber product in each field because it has a small permanent strain and is excellent in flexibility and mechanical properties. In particular, the crosslinked rubber according to the present invention is obtained by crosslinking a rubber composition containing the copolymer (A) having a small amount of low molecular weight components, so that it is further excellent in mechanical properties.
Examples of uses of the crosslinked rubber of the present invention include tires, footwear, rubber rolls, conductive rubbers, conveyor belt cover rubbers, medical rubber products, floor materials, and the like.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. The measuring method of each physical property is as follows.
<Weight average molecular weight (Mw), number average molecular weight (Mn), molecular weight distribution (Mw / Mn) of copolymer (A)>
The obtained copolymer (A) was dissolved in a 1: 1 mixed solution of chloroform and hexafluoroisopropanol, and then diluted with chloroform to prepare a 0.1% (w / v) solution. Gel permeation chromatography [Waters GPC system, detector: RI (Waters 2414), column: PLgel 5μ MIXED-D (Polymer Laboratories), column temperature: 40 ° C., flow rate: 1 ml / min , Solvent: chloroform], a weight average molecular weight (Mw), a number average molecular weight (Mn), and a molecular weight distribution (Mw / Mn) were calculated based on a polystyrene standard sample.

<Composition of copolymer (A)>
The composition of the copolymer (A) was analyzed by the following procedure.
1) An ECA500 nuclear magnetic resonance apparatus manufactured by JEOL Ltd. was used, and deuterated chloroform was used as a solvent. The sample concentration was 35 mg / 0.5 mL, and the measurement temperature was 50 ° C.
The observation nucleus is ¹ H (500 MHz), the sequence is a single pulse, the pulse width is 6.3 μs (45 ° pulse), the repetition time is 8.5 seconds, the integration number is 394 times, and the hydrogen signal of tetramethylsilane is chemically It was measured as a reference value for shift. Each peak was assigned by a conventional method.
2) The obtained measurement data was analyzed, the carboxylic acid and alcohol component which comprise a copolymer (A) were identified, and those structural ratios were calculated | required.

<Evaluation of physical properties of unvulcanized rubber>
(Mooney viscosity (ML (1 + 4) 100 ° C))
The Mooney viscosity at 100 ° C. (ML (1 + 4) 100 ° C.) was measured under the condition of 100 ° C. using a Mooney viscometer (SMV202 type, manufactured by Shimadzu Corporation) in accordance with JIS K6300.

(Vulcanization speed)
Using the uncrosslinked rubber compositions in Examples and Comparative Examples, the vulcanization rate (TC90) was measured using the measurement apparatus: MDR2000P (manufactured by ALPHA TECHNOLOGIES) under the measurement conditions of a temperature of 160 ° C. and an hour of 30 minutes. Measured as follows.

The sample was set in a measuring apparatus, and the torque change obtained under the conditions of a constant temperature and a constant shear rate was measured to obtain a vulcanization curve. The minimum value S ′ _Min and the maximum value S ′ _Max of the torque are obtained from this vulcanization curve, and the time until the torque reaches (S ′ _Max −S ′ _Min ) × 0.9 with the measurement start as a reference is vulcanized. The speed (TC90; minutes) was used.

<Evaluation of physical properties of vulcanized rubber>
(Tensile breaking stress, tensile breaking elongation)
The stress at break and the elongation at break of the sheet were measured by the following methods.
A No. 3 dumbbell test piece described in JIS K 6251 (1993) was prepared by punching the sheet, and using this test piece, the measurement temperature was 25 ° C. according to the method defined in JIS K6251 item 3. A tensile test was performed under the condition of a tensile speed of 500 mm / min, and tensile stress at break (TB) and tensile elongation at break (EB) were measured.

(Durometer A hardness)
In accordance with JIS K 6253, the sheet hardness (type A durometer, HA) was measured by stacking flat portions with a thickness of about 12 mm using six 2 mm sheet-like rubber molded products having a smooth surface. However, those in which foreign matter was mixed in the test piece, those having bubbles, and those having scratches were not used. Moreover, the dimension of the measurement surface of the test piece was set to such a size that measurement was possible at a position where the tip of the push needle was 12 mm or more away from the end of the test piece.

(Bleedability)
As a test piece (diameter: 29 mm; thickness: 12.5 mm), a punched out rubber sheet obtained from the rubber composition was used.
In a compression apparatus having a pair of compression plates, a spacer, and a holder for fixing them, a test piece is inserted between the pair of compression plates, and the holder is tightened until these compression plates are in close contact with the spacer. Fixed in state. Here, the thickness of the spacer was set so that the compression rate of the test piece was 25%. The compression apparatus incorporating the test piece was heat-treated at 70 ° C. for 24 hours. Thereafter, the test piece was released from the compression apparatus and left in a constant temperature room at 23 ° C. for 30 minutes. About the test piece obtained by performing such compression and heat treatment, the surface was observed and judged as follows.
There is stickiness: ×
No stickiness: ○

<Rubber (X)>
The polymers used as rubber (X) in the following Examples and Comparative Examples are as shown in Table 1 below.

<(Co) polymer (A)>
[Production Example 1] (Production of ricinoleic acid copolymer P-1)
Into a 500 ml glass polymerization reaction flask, 0.04 part by mass of ricinoleic acid, 13.6 parts by mass of sebacic acid, and 9.7 parts by mass of 1,4-butanediol were added with a 20 wt% aqueous solution of calcium acetate monohydrate. 31 mass parts, 0.27 mass part of 20 wt% aqueous solution of magnesium acetate tetrahydrate was added, and it heated up from normal temperature to 210 degreeC over 30 minutes. After reaching 210 ° C., 0.20 parts by mass of titanium tetrabutoxide and 0.03 parts by mass of a 20 wt% aqueous solution of tetraethylammonium hydroxide were added and held at 210 ° C. for 5 hours to carry out an esterification reaction.

After completion of the esterification reaction, 1.36 parts by mass of titanium tetrabutoxide was added, and then the pressure was reduced to 0.133 kPa (1 Torr) while raising the temperature to 230 ° C., which is a polycondensation temperature, over 60 minutes. went. Periodically, a small amount of the reaction product was withdrawn and the molecular weight was measured. The reaction was terminated when the molecular weight Mw reached 116,000 (heating time at the polycondensation temperature: 3 hours), and the polyester produced from the reaction vessel was extracted within 10 minutes from the completion of the reaction.
In the following Comparative Example 1, the obtained polyester was used as the polymer P-1.
The obtained polymer P-1 had a weight average molecular weight Mw of 116,000, a number average molecular weight Mn of 14400, and a molecular weight distribution (Mw / Mn) of 8.1.

[Production Example 2] (Production of ricinoleic acid copolymer P-2)
After obtaining polymer P-1 in the same manner as in Production Example 1, 400 parts by weight of xylene was added to 100 parts by weight of polymer P-1 to completely dissolve the polymer P-1. Thereafter, 500 parts by weight of methanol was added to precipitate the high molecular component, and then the solvent in which the low molecular component was dissolved was removed. This operation was repeated 3 times to obtain a polymer from which low molecular weight components were removed.
In the following Example 1, the obtained polymer was used as the polymer P-2.
The obtained polymer P-2 had a weight average molecular weight Mw of 141,000, a number average molecular weight Mn of 26400, and a molecular weight distribution (Mw / Mn) of 5.3.
The characteristic values of the polymers P-1 and P-2 are shown in Table 2.

<Preparation of rubber composition and crosslinked product>
[Example 1]
Polymer P-11 was used as rubber (X). For 100 parts by mass of polymer P-11, 10 parts by mass of polymer P-2 as a copolymer (A) and 40 parts by mass of process oil (Diana Process Oil AH-16: manufactured by Idemitsu Kosan Co., Ltd.) as a plasticizer, as a reinforcing material 40 parts by mass of carbon black (Asahi # 80: manufactured by Asahi Carbon Co., Ltd.), silica as a reinforcing material (nip seal VN3: manufactured by Tosoh Silica Co., Ltd.) 40 parts by mass, “Zinc oxide 2 types” (Trade name; manufactured by Sakai Chemical Industry Co., Ltd.) 3 parts by mass, 2 parts by mass of stearic acid as a processing aid, 2.7 parts by mass of diethylene glycol (DEG) as an activator, and bis [3- (Triethoxysilyl) propyl] tetrasulfide (Si69: manufactured by Evonik) After mixing 4 parts by mass, 6 inch opening with a roll temperature of 50 ° C. Roll (Nipkow Koki Co., roll rotation speed: front 15 rpm, rear 18 rpm) using a 6 times through rounding roll spacing 0.2 mm, to obtain a blend by performing tight milling 3 times.

The obtained blend was wound around the 6-inch open roll, and N-cyclohexyl-2-benzothiazolesulfenamide (Sunceller CM: manufactured by Sanshin Chemical Industry Co., Ltd.) as a vulcanization accelerator, 1.7 parts by mass, After mixing 2 parts by mass of 1,3-diphenylguanidine (DPG) as a vulcanization accelerator and 1.4 parts by mass of powdered sulfur as a crosslinking agent (C), a 6-inch open roll having a roll temperature of 50 ° C. (described above) The ricinoleic acid copolymer rubber composition was obtained by turning back and forth three times with a roll gap of 0.2 mm, rounding six times, and further thinning three times.
The physical properties of the uncrosslinked rubber of the obtained rubber composition were measured based on the above “evaluation of physical properties of unvulcanized rubber”.

  Furthermore, the rubber composition was pressed at 160 ° C. for 10 minutes to prepare a rubber sheet having a thickness of 2 mm as a rubber crosslinked body. Based on the above “evaluation of physical properties of vulcanized rubber”, the durometer A hardness, breaking strength TB (MPa) and breaking elongation EB (%) of the obtained rubber sheet were measured.

Separately from this, the rubber composition was pressed at 160 ° C. for 10 minutes to prepare a molded body having a thickness of 12.5 mm and a diameter of 29 mm, which was used as a test piece for evaluating bleeding.
The evaluation results are shown in Table 3.

[Comparative Example 1]
The same procedure as in Example 1 was performed except that polymer P-1 was used instead of polymer P-2. The evaluation results are shown in Table 3.

[Comparative Example 2]
The same procedure as in Example 1 was performed except that the polymer P-2 was not used and the amount of the process oil was changed to 50 parts by mass instead. The evaluation results are shown in Table 3.

Claims (4)

100 parts by weight of crosslinkable rubber (X),
1 to 50 parts by mass of a copolymer (A) of ricinoleic acid and / or a derivative thereof [α], a dicarboxylic acid [β], and a diol [γ] satisfying at least the following requirements (1) to (3) When,
A rubber composition comprising 0.01 to 10 parts by mass of a crosslinking agent (C).
(1) The content of the structural unit derived from ricinoleic acid and / or its derivative [α] is a structural unit derived from the aforementioned ricinoleic acid and / or its derivative [α], and a structural unit derived from dicarboxylic acid [β]. , 10 mol% or more and less than 100 mol% with respect to the total with the structural unit derived from diol [γ];
(2) The weight average molecular weight Mw measured by GPC (gel permeation chromatography) of the copolymer (A) is 10,000 or more and 500,000 or less;
(3) The ratio (Mw / Mn) of the weight average molecular weight Mw and the number average molecular weight Mn of the copolymer (A) is 2 or more and 6 or less.   The said copolymer (A) contains at least 1 sort (s) chosen from the group which consists of a C2-C12 dicarboxylic acid [(beta) 1] and a C2-C12 diol [(gamma) 1] component. Rubber composition. The copolymer (A) is
(I) 10 to 80 mol% of structural units derived from ricinoleic acid and / or its derivative [α],
(II) 10 to 45 mol% of structural units derived from dicarboxylic acid [β1] having 2 to 12 carbon atoms and (III) 10 to 45 mol% of structural units derived from diol [γ1] having 2 to 12 carbons.
(However, the total of structural units (I), (II), and (III) is 100 mol%)
The rubber composition according to claim 1, comprising:   The crosslinkable rubber (X) is natural rubber (NR), isoprene rubber (IR), butyl rubber (IIR), butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), 4. One or more kinds selected from the group consisting of chloroprene rubber (CR), ethylene-propylene rubber (EPR), and ethylene-propylene-diene rubber (EPDM). The rubber composition as described.