WO2016163253A1

WO2016163253A1 - Elastomer composition

Info

Publication number: WO2016163253A1
Application number: PCT/JP2016/059820
Authority: WO
Inventors: 伸一中出
Original assignee: 伸一中出
Priority date: 2015-04-06
Filing date: 2016-03-28
Publication date: 2016-10-13
Also published as: JP2016196585A; JP6373789B2

Abstract

[Problem] To provide an elastomer composition that can be easily manufactured and has an excellent flexibility. [Solution] An elastomer composition comprising, as major components, a peptide that contains 4.0-30 mass% inclusive of cystine and a polymer that carries at least one kind of polar group selected from the group consisting of a halogen group, sulfone group, carbonyl group, amino group, imino group, carboxyl group, hydroxyl group, sulfide group, disulfide group, sulfonyl group, amide group and nitrile group. This elastomer composition has a crosslinked structure that is formed on the basis of an electrostatic interaction and hydrophobic effect of the peptide and the polymer. The 300% modulus of this elastomer composition (ME₃₀₀) is smaller than the 300% modulus of the polymer (MP₃₀₀).

Description

Elastomer composition

The present invention relates to an elastomer composition and a method for producing the same.

Elastomer compositions are used in many fields such as industrial products such as tires, belts and hoses, medical-related products such as gloves and masks, and household products such as toys. A typical elastomer composition is vulcanized rubber. The vulcanized rubber is formed by heating and pressurizing a rubber composition containing a base rubber, a vulcanizing agent, a vulcanization accelerator, an anti-aging agent, a reinforcing agent and the like. Natural rubber is frequently used as a base rubber that is inexpensive and has excellent mechanical properties.

Regarding vulcanized rubber, protein components in natural rubber latex collected from plants are known to induce acute allergies. In addition, delayed allergy may be induced depending on the type of vulcanization accelerator and anti-aging agent. Environmental problems such as elution of zinc ions from zinc oxide (zinc oxide), which is a vulcanization accelerator, have been pointed out.

For applications such as medical-related products and household products, highly safe elastomer compositions are required. In addition, in applications intended for infants and the elderly, there is a demand for elastomer compositions that are more flexible than conventional vulcanized rubber products and have high stretchability.

In the case of vulcanized rubber, high temperature and high pressure treatment is required not only in the production process but also in the recycling process. From the viewpoint of energy saving and resource saving, thermoplastic elastomers that are easy to process and recycle are being investigated as an alternative to vulcanized rubber, but their mechanical properties are not fully satisfactory.

JP-A-2009-114250, JP-A-6-166671 and JP-A-8-12814 disclose rubber compositions for which various studies have been made.

JP 2009-114250 A relates to a rubber composition containing a diene rubber and gluten. This rubber composition contains a vulcanization accelerator and the like. In the vulcanized rubber made of this rubber composition, gluten and diene rubber are chemically bonded. The vulcanized rubber has a high breaking strength (tensile strength) and modulus. Vulcanized rubber having a high breaking strength and modulus is not suitable for use in applications requiring flexibility and stretchability.

JP-A-6-166671 and JP-A-8-12814 propose rubber compositions and rubber products that do not contain a vulcanizing agent or the like.

JP 2009-114250 A JP-A-6-166671 JP-A-8-12814

In the rubber compositions disclosed in JP-A-6-166671 and JP-A-8-12814, a protein is blended for improving the modulus. The stretchability and flexibility of rubber products made of these rubber compositions are not fully satisfactory.

In JP-A-6-166671 and JP-A-8-12814, a thiol group (—SH) in a protein contributes to the formation of a chemical bond with a rubber molecule. A thiol group contained in a protein is usually oxidized in air to form a cystine bond (—SS—). It is not easy to industrially produce and stably use a protein having a thiol group. On the other hand, an elastomer composition containing a protein having a cystine bond and excellent in flexibility and stretchability has not yet been studied.

An object of the present invention is to provide an elastomer composition excellent in flexibility and stretchability and easy to produce and a method for producing the same.

The elastomer composition according to the present invention comprises a peptide containing 4.0% by mass to 30% by mass of cystine, a halogen group, a sulfone group, a carbonyl group, an amino group, an imino group, a carboxyl group, a hydroxyl group, a sulfide group, It contains as a main component a polymer having at least one polar group selected from the group consisting of a disulfide group, a sulfonyl group, an amide group and a nitrile group. This elastomer composition has a crosslinked structure formed on the basis of electrostatic interaction between a peptide and a polymer and a hydrophobic effect. The 300% modulus ME ₃₀₀ of this elastomer composition is smaller than the 300% modulus MP ₃₀₀ of the main polymer.

Preferably, the 300% modulus ME ₃₀₀ of this elastomer composition is 0.1 MPa or more and 1.0 MPa or less. Preferably, the breaking strength Tb of this elastomer composition is 0.1 MPa or more and 6.5 MPa or less.

Preferably, the absolute value of the zeta potential of this polymer is 30 mV or more. Preferably, the polymer is natural rubber that has not been deproteinized.

Preferably, the amount of the peptide with respect to 100 parts by mass of the polymer is 1.0 part by mass or more and 20 parts by mass or less.

Preferably, the elastomer composition is substantially free of vulcanizing agent, vulcanization accelerator and vulcanization acceleration aid.

Preferably, this peptide contains 5.0% by mass or more and 15% by mass or less of cystine bonds. Preferably, the amount of thiol group contained in the peptide is 1.0% by mass or less.

Preferably, the peptide is a fine particle insoluble in water. Preferably, the average particle diameter of the fine particles is 0.1 μm or more and 1.0 μm or less.

The method for producing an elastomer composition according to the present invention comprises:
(1) A peptide containing 4.0% by mass to 30% by mass of cystine, a halogen group, a sulfone group, a carbonyl group, an amino group, an imino group, a carboxyl group, a hydroxyl group, a sulfide group, a disulfide group, a sulfonyl group, A first step of obtaining a mixture by mixing a polymer having at least one polar group selected from the group consisting of an amide group and a nitrile group in an aqueous medium;
(2) The mixed solution is dried to form a crosslinked structure based on electrostatic interaction and hydrophobic effect between the polymer and the peptide, so that the 300% modulus ME ₃₀₀ is 300 A second step of obtaining an elastomer composition smaller than% modulus MP ₃₀₀ .

The elastomer composition according to the present invention has a crosslinked structure formed on the basis of electrostatic interaction and hydrophobic effect between a peptide as a main component and a polymer. This elastomer composition is excellent in flexibility and stretchability. A molded article made of this elastomer composition gives a proper feeling to the user. Further, the production of this elastomer composition does not require blending of a vulcanizing agent or the like, or high temperature / high pressure operation. This elastomer composition can be easily and inexpensively produced.

Hereinafter, although it demonstrates in detail based on preferable embodiment of this invention, the scope of the present invention is limited to this embodiment and is not interpreted. Various modifications are possible within a range that does not impair the gist of the present invention, including the following embodiments. The terms used in this specification are defined according to JIS K6200 “Rubber-Terminology” unless otherwise specified.

(Elastomer composition)
The main component of the elastomer composition according to the present invention is a peptide containing 4.0% by mass to 30% by mass of cystine, a halogen group, a sulfone group, a carbonyl group, an amino group, an imino group, a carboxyl group, a hydroxyl group, A polymer having at least one polar group selected from the group consisting of sulfide groups, disulfide groups, sulfonyl groups, amide groups and nitrile groups. This elastomer composition has a cross-linked structure formed mainly from a peptide and a polymer.

In this cross-linked structure, it is presumed that the molecular chain of the polymer is constrained by the cross-linking points formed based on the electrostatic interaction between the peptide and the polymer and the hydrophobic effect. The binding force of the polymer chain by the crosslinking point formed based on the electrostatic interaction and the hydrophobic effect is smaller than the binding force by the chemical crosslinking point formed by the covalent bond. In the elastomer composition having a crosslinked structure formed on the basis of electrostatic interaction and hydrophobic effect, excellent flexibility and stretchability are achieved.

Furthermore, the elastomer composition according to the present invention has sufficient heat resistance as a molded product despite having no chemical cross-linking structure based on a covalent bond. The detailed mechanism of the cross-linked structure in the present invention has not been clearly elucidated, but the inventor's estimation is as follows.

For example, a polymer having a polar group such as a halogen group has a negative surface charge in an aqueous medium. When this polymer and a peptide containing cystine are mixed, it is considered that the polymer chain and the peptide molecule aggregate due to electrostatic interaction to form an aggregate. Thereafter, natural drying is performed at room temperature to remove the aqueous medium, so that the polymer chain and the peptide molecule further approach inside the assembly. Presumed that due to the approach of the molecular chain, the electron cloud formed near the polar group in the polymer chain and the electron cloud near the cystine bond in the peptide approach each other and overlap each other, thereby forming a crosslinking point. Is done. This overlap of electron clouds is thought to occur not only within the assembly but also between the assemblies. The overlap of multiple electron clouds inside and between aggregates acts cooperatively, resulting in a chemically cross-linked structure despite the covalent bond breaking and recombination in macromolecules and peptides. It is considered that an approximate strong cross-linked structure is formed. Furthermore, according to this mechanism, it is speculated that the amino acid sequence of the peptide, particularly the site and amount of the cystine bond, influence the formation of the crosslinked structure.

As long as the object of the present invention is not hindered, the elastomer composition according to the present invention may contain a chemically crosslinked structure. In this elastomer composition, a crosslinked structure may be formed based on other intermolecular interactions between the peptide and the polymer.

As described above, the elastomer composition having a crosslinked structure formed based on the electrostatic interaction between the peptide and the polymer and the hydrophobic effect is excellent in flexibility and stretchability. In the specification of the present application, the flexibility and stretchability of the elastomer composition are indicated with an index of 300% modulus measured according to the method described in JIS K6251. Furthermore, the 300% modulus ME ₃₀₀ of the elastomeric composition according to the present invention is defined as the measurement value of a test piece consisting of an elastomeric composition containing only peptides and polymers and substantially no other additives.

The 300% modulus ME ₃₀₀ of the elastomer composition according to the present invention is smaller than the 300% modulus MP _{300 of the} polymer contained as its component. In other words, the ratio of 300% modulus ME ₃₀₀ of the elastomer composition according to the present invention to 300% modulus MP ₃₀₀ of the polymer (ME ₃₀₀ / MP ₃₀₀ ) is less than 1. In light of flexibility and stretchability, the ratio (ME ₃₀₀ / MP ₃₀₀ ) is preferably 0.95 or less, and more preferably 0.90 or less. A preferable ratio (ME ₃₀₀ / MP ₃₀₀ ) from the viewpoint of durability is 0.50 or more.

The 300% modulus ME ₃₀₀ of the elastomer composition according to the present invention is preferably 1.0 MPa or less. An elastomer composition having an ME ₃₀₀ of 1.0 MPa or less is soft and easily stretched with a small force. From this viewpoint, the ME _{300 of the} elastomer composition is more preferably 0.9 MPa or less, and further preferably 0.80 MPa or less. ME ₃₀₀ preferable from the viewpoint of durability is 0.1 MPa or more.

The breaking strength Tb of the elastomer composition according to the present invention is preferably 0.1 MPa or more and 6.5 MPa or less. A more preferable breaking strength Tb from the viewpoint of durability is 0.5 MPa or more. From the viewpoints of flexibility and stretchability, the more preferable breaking strength Tb is 6.3 MPa or less. The breaking strength Tb of the elastomer composition according to the present invention is based on the method described in JIS K6251 using a test piece made of an elastomer composition containing only a peptide and a polymer and substantially no other additives. Measured value.

Preferably, the elastomer composition contains 1.0 part by mass or more and 20 parts by mass or less of peptide with respect to 100 parts by mass of the polymer. From the viewpoint of forming a crosslinked structure, the amount of the peptide is more preferably 1.5 parts by mass or more, and further preferably 2.0 parts by mass or more. From the viewpoint of cost, a more preferable amount of peptide is 10 parts by mass or less.

(High molecular)
The polymer used in the elastomer composition according to the present invention includes halogen groups, sulfone groups, carbonyl groups, amino groups, imino groups, carboxyl groups, hydroxyl groups, sulfide groups, disulfide groups, sulfonyl groups, amide groups, and nitrile groups. Having at least one polar group selected from the group consisting of It is speculated that the polar group of the polymer contributes to the formation of a crosslinked structure by imparting a large surface charge in an aqueous medium. From this viewpoint, more preferable polar groups are a halogen group, a carboxyl group, a sulfide group, a disulfide group, and a nitrile group. From the viewpoint of affinity with a peptide containing cystine, particularly preferred polar groups are a sulfide group and a disulfide group. As long as the object of the present invention is achieved, the polymer may contain other polar groups or non-polar functional groups. Two or more kinds of polymers having different polar groups may be mixed and used.

As long as a crosslinked structure based on electrostatic interaction and hydrophobic effect can be formed, the structure of the polymer having a polar group is not particularly limited. The polar group may be contained in the main chain of the polymer or may be bonded to the side chain or terminal of the polymer. When the polar group is bonded to the side chain or the terminal, the type of polymer serving as the main chain is not particularly limited. From the viewpoint of mechanical properties, rubber polymers and thermoplastic elastomers can be suitably used.

Specific examples of the rubber-based polymer having a polar group include natural rubber (NR), chlorinated natural rubber, chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), acrylonitrile-isoprene rubber (NIR), acrylonitrile-butadiene- Isoprene rubber (NBIR), hydrogenated nitrile rubber (HNBR), acrylic rubber (ACM), ethylene-acrylic rubber (AEM), carboxylated butadiene rubber (XBR), carboxylated chloroprene rubber (XCR), carboxylated acrylonitrile-butadiene rubber (XNBR), brominated butyl rubber (BIIR), chlorinated butyl rubber (CIIR), vinylpyridine-butadiene rubber (PBR), vinylpyridine-styrene-butadiene rubber (PSBR), chlorosulfonated polyethylene Beam, and the like.

Further, rubber polymers that can be used as the main chain include isoprene rubber (IR), butadiene rubber (BR), 1,2-butadiene rubber, styrene-butadiene rubber (SBR), butyl rubber (IIR), ethylene-propylene- Examples include diene rubber (EPDM), ethylene-propylene rubber (EPM), ethylene-butene rubber (EBM), and polyethylene rubber.

Examples of thermoplastic elastomers include styrene block-containing elastomers, polyvinyl chloride elastomers, polyamide elastomers, polyolefin elastomers, polyurethane elastomers, polyester elastomers, and the like. A thermoplastic elastomer and a rubber-based polymer may be mixed and used. As long as the object of the present invention is achieved, a resin other than the rubber polymer and the thermoplastic elastomer may be mixed.

It has at least one polar group selected from the group consisting of halogen groups, sulfone groups, carbonyl groups, amino groups, imino groups, carboxyl groups, hydroxyl groups, sulfide groups, disulfide groups, sulfonyl groups, amide groups, and nitrile groups. When the polymer further includes a double bond, it is considered that a stronger cross-linked structure is formed by the overlap of the electron cloud of the double bond and the polar group. From this viewpoint, preferred polymers are diene rubbers such as chloroprene rubber and acrylonitrile-butadiene rubber, and natural rubber.

Natural rubber is composed of an ω-terminal bonded to protein, two trans-1,4-isoprene units, about 1000 cis-1,4-isoprene units, and an α-terminal bonded to lipid. In the case of natural rubber, it is considered that a double bond in the main chain and a polar group in a constituent amino acid of a protein interact with a peptide molecule. In the present invention, when natural rubber is used as a polymer, natural rubber that has not been deproteinized is preferred.

The method for producing the polymer used in the elastomer composition according to the present invention is not particularly limited. Examples thereof include a method based on a polymerization reaction of a monomer having a predetermined polar group, a method based on a chemical reaction between a polymer serving as a main chain and a specific compound. For example, a method of producing a carboxyl group-containing diene rubber by reacting a diene rubber containing a double bond with a carboxylic anhydride.

In the elastomer composition according to an embodiment of the present invention, a latex in which fine particles made of polymer are colloidally dispersed in an aqueous medium is manufactured and used. The surface of the fine particle composed of a polymer having a polar group is positively or negatively charged in an aqueous medium. From the viewpoint of promoting electrostatic interaction with a peptide, a polymer having a large surface charge is preferred.

In the present specification, the surface charge of the polymer fine particles is indicated by zeta potential. Zeta potential is defined as the potential difference between a stationary fluid layer on the surface of a microparticle dispersed in an aqueous medium and the aqueous medium.

A polymer having an absolute value of zeta potential of 30 mV or more is preferable. From the viewpoint of the affinity between the peptide and the polymer, a polymer having an absolute value of zeta potential of 40 mV or higher is more preferable, a polymer of 45 mV or higher is more preferable, and a polymer of 50 mV or higher is particularly preferable. The upper limit of the absolute value of the zeta potential is not particularly limited, but is preferably 200 mV or less from the viewpoint of manufacturing cost and the like. In the present specification, the zeta potential of the polymer was measured with a zeta potential measuring device (ELSZ-1000Z manufactured by Otsuka Electronics Co., Ltd.) for a dispersion (pH 7, 25 ° C.) containing about 0.05% by mass of the polymer. When defined as a measured value.

(peptide)
In the present specification, “peptide” is defined as a general term for compounds in which two or more molecules of amino acids are linked by peptide bonds. Usually, a peptide consisting of 2 to 10 amino acids is called an oligopeptide. A peptide consisting of 10 to 100 amino acids is called a polypeptide. A compound in which more than 100 amino acids are bound is called a protein. Unless otherwise stated, the term “peptide” herein includes dipeptides, tripeptides, oligopeptides, polypeptides and proteins.

The peptide used in the elastomer composition according to the present invention contains cystine as a constituent amino acid. The cystine content [Cys] with respect to all constituent amino acids of this peptide is 4.0% by mass or more and 30% by mass or less. From the viewpoint of promoting electrostatic interaction with the polymer, the cystine content [Cys] is preferably 5.0% by mass or more, and more preferably 6.0% by mass or more. From the viewpoint of production and availability, the preferred cystine content [Cys] is 20% by mass or less. In the specification of the present application, the cystine content [Cys] in the peptide is an amino acid automatic analyzer (a fully automatic amino acid analyzer “JLC-500 / V” manufactured by JEOL Ltd., column: strongly acidic cation exchange resin LCR-6). Is measured.

A mixed peptide containing two or more peptides having different cystine contents may be used. The mixed peptide may include a peptide having a cystine content of less than 4.0% by mass. This mixed peptide is prepared so that the average value of cystine content with respect to all constituent amino acids in the peptide is 4.0% by mass or more and 30% by mass or less. The types and ratios of the other constituent amino acids in the peptide are appropriately selected within a range in which the object of the present invention is not inhibited.

There is a peptide containing cysteine as a constituent amino acid. Cysteine has a thiol group (-SH). Thiol groups are easily oxidized in air. Oxidation forms cystine with a cystine bond (-SS-) from two molecules of cysteine. Most of the cysteines in the peptide are contained as cystine.

In the elastomer composition according to the present invention, it is presumed that the cystine bond (-SS-) in the peptide contributes to the formation of a crosslinked structure by interacting with the polymer chain. From the viewpoint of flexibility and stretchability of the obtained elastomer composition, the amount of cystine bond in the peptide is preferably 5.0% by mass or more, more preferably 6.0% by mass or more, and further 7.0% by mass. preferable. From the viewpoint of easy production and availability, the preferable amount of cystine bond is 15% by mass or less.

The peptide used in the elastomer composition according to the present invention does not substantially contain a thiol group (-SH), but the peptide may contain a thiol group as long as the object of the present invention is achieved. The thiol group content in the peptide is preferably 1.0% by mass or less, more preferably 0.9% by mass or less, and further preferably 0.8% by mass or less.

As long as the object of the present invention is achieved, a method for obtaining a peptide containing 4.0% by mass or more and 30% by mass or less of cystine is not particularly limited. For example, extraction from a natural product, hydrolysis of a protein derived from a natural product, genetic engineering, synthesis by a liquid phase method or a solid phase method and the like can be mentioned. A method of hydrolyzing a natural product-derived protein with an acid, alkali or enzyme is preferably used. Hydrolysis conditions are appropriately selected depending on the type of natural product-derived protein. A peptide containing cystine may be obtained by hydrolyzing a natural product-derived protein containing cysteine, followed by further oxidation treatment.

Proteins derived from natural products containing cystine or cysteine include keratin and cuticles contained in animal hair, feathers, eggshell membranes, nails, horns, shells, silk threads, etc., α-lactalbumin, β-lactoglobulin contained in whey Examples include animal-derived proteins such as serum albumin, ovalbumin and ovotransferrin contained in egg white. Plant-derived proteins contained in wheat, rice, soybeans and the like may be used. Keratins, cuticles, glutenins and oryzins with high cystine and cysteine content are preferred. From the viewpoint of safety, more preferred proteins are keratin, cuticle and oryzinin.

When a natural product-derived protein is hydrolyzed, a peptide bond is cleaved to generate a peptide having a molecular weight of several thousand to several tens of thousands. The molecular weight of the peptide obtained depends on the type of protein as a raw material and hydrolysis conditions. As long as the object of the present invention is achieved, the molecular weight of the peptide is not particularly limited. The molecular weight of a peptide that is preferable from the viewpoint of miscibility with a polymer is 10,000 or less, more preferably 8,000 or less, and still more preferably 5,000 or less. Two or more peptides having different molecular weights may be mixed and used.

In the present specification, the molecular weight of a peptide is defined as the number average molecular weight measured under the following measurement conditions by exclusion limit chromatography (SEC) using a high performance liquid chromatograph.
Apparatus: HPC-8220GPC (manufactured by Tosoh Corporation)
Column: TSK-gel GMPW-XL (manufactured by Tosoh Corporation)
Eluent: Dimethylformamide (DMF)
Column temperature: 40 ° C
Flow rate: 1.0 (ml / min.)
Detector: differential refractometer RI-8022
Reference material: 6-mercaptopurine monohydrate

The peptide used in the present invention may be water-soluble or water-insoluble. When the peptide is insoluble in water, it is preferable to use fine particles having an average particle size of 1.0 μm or less from the viewpoint of mixing with a polymer. The lower limit of the average particle diameter of the peptide fine particles is not particularly limited, but is preferably 0.1 μm or more from the viewpoint of easy production. The average particle diameter of the peptide fine particles is measured by a dynamic light scattering method. A mixture of a water-soluble peptide and water-insoluble peptide fine particles may be used.

(Method for producing elastomer composition)
The elastomer composition according to an embodiment of the present invention is manufactured according to the following steps.

In this embodiment, first, a latex in which fine particles made of a polymer are colloidally dispersed in an aqueous medium is prepared. The polymer is at least one selected from the group consisting of halogen groups, sulfone groups, carbonyl groups, amino groups, imino groups, carboxyl groups, hydroxyl groups, sulfide groups, disulfide groups, sulfonyl groups, amide groups, and nitrile groups. It has a polar group.

In the present invention, the polymer content in the latex is not particularly limited. From the viewpoint of miscibility with the peptide, latex containing a polymer of 30% by mass or more and 70% by mass or less as the solid content is preferable. A more preferable polymer content is 40% by mass or more and 60% by mass or less.

From the viewpoint of dispersion stability of latex, the average particle size of the fine particles made of polymer is preferably 0.5 μm or less, and more preferably 0.4 μm or less. From the viewpoint of ease of production, the preferred average particle size is 0.01 μm or more. The average particle diameter of the polymer fine particles is measured by a dynamic light scattering method using a laser diffraction particle size distribution measuring apparatus.

A typical aqueous medium contained in latex is water. As long as the object of the present invention is achieved, the aqueous medium may contain an organic solvent. A hydrophilic organic solvent capable of uniform mixing with water is preferred. Specific examples of the hydrophilic organic solvent include lower alcohols such as methanol and ethanol, and polyhydric alcohols such as ethylene glycol and glycerin. As long as the interaction with the peptide is not inhibited, additives such as a dispersion stabilizer, an emulsifier, and a surfactant may be added to the aqueous medium.

In the present invention, the method for obtaining latex is not particularly limited. For example, at least one polar group selected from the group consisting of halogen groups, sulfone groups, carbonyl groups, amino groups, imino groups, carboxyl groups, hydroxyl groups, sulfide groups, disulfide groups, sulfonyl groups, amide groups, and nitrile groups And a method of emulsion polymerization of a monomer having a surfactant in the presence of a surfactant.

In another embodiment of the present invention, natural rubber latex collected from plants is used as the latex. Natural rubber latex is a dispersion in which rubber particles having an average particle diameter of about 1 μm are dispersed in water. Natural rubber latex that has not been deproteinized is preferred. In the elastomer composition according to the present invention, it is presumed that proteins in natural rubber latex contribute to the formation of a crosslinked structure. As long as the object of the present invention is achieved, a deproteinized natural rubber latex may be used.

Subsequently, a peptide is added to the prepared latex to form a mixed solution containing the polymer and the peptide. This peptide contains 4.0% by mass to 30% by mass of cystine as a constituent amino acid.

Preferably, 1.0 part by mass or more and 20 parts by mass or less of the peptide is added with respect to 100 parts by mass of the polymer solid content in the latex. From the viewpoint of forming a crosslinked structure, the amount of the peptide is more preferably 1.5 parts by mass or more, and further preferably 2.0 parts by mass or more. From the viewpoint of cost, a more preferable amount of peptide is 10 parts by mass or less.

In the present invention, the peptide may be added to the latex as an aqueous solution, or may be added to the latex as a dispersion of peptide fine particles. An aqueous solution prepared from a water-soluble peptide and a dispersion of water-insoluble peptide fine particles may be used in combination. In this production method, regardless of whether the peptide is water-soluble or not, hydrophobic interaction due to electrostatic interaction and hydrophobic effect can occur between the polymer fine particles in the latex.

As the next step, the mixed solution containing the polymer and the peptide is put into a predetermined drying container and dried to produce the elastomer composition according to the present invention.

The drying conditions of the mixed solution containing the polymer and the peptide are appropriately selected depending on the amount of the mixed solution and the shape of the drying container. From the viewpoint that cleavage of the cystine group in the peptide and formation of a covalent bond with the polymer are suppressed, the drying temperature is preferably 100 ° C. or lower, more preferably 90 ° C. or lower, and further preferably 80 ° C. or lower. From the viewpoint of drying efficiency, a preferable drying temperature is 15 ° C. or higher. The ideal drying condition is natural drying at room temperature. In the present specification, room temperature means 25 ° C. or higher and 30 ° C. or lower.

The drying time is adjusted using the amount of reduction of the aqueous medium in the mixed solution as an index. A drying time during which 90% by mass or more of the aqueous medium contained in the mixed solution before drying is removed is preferable. More preferably, the drying time is adjusted so that 95% by mass or more, more preferably 98% by mass or more of the aqueous medium is removed.

In this embodiment, the elastomer composition is substantially free of a vulcanizing agent, a vulcanization accelerator, and a vulcanization acceleration aid. This elastomer composition does not include a crosslinked structure in which polymer chains are crosslinked by a vulcanizing agent or the like. This elastomer composition achieves a 300% modulus that is smaller than conventional vulcanized rubber products. A molded article made of this elastomer composition is easily deformed with a small force. When this molded product is applied to the human body, it gives a comfortable feeling to the user. When this elastomer composition is applied to toys for infants, gloves for elderly people, and the like, a particularly excellent feeling of use is achieved.

In other embodiments, a vulcanizing agent, a vulcanization accelerator, a vulcanization acceleration aid, a reinforcing agent, a colorant, an antiaging agent, etc. These additives are blended and subjected to a vulcanization process. This elastomer composition includes a crosslinked structure based on electrostatic interaction and a hydrophobic effect, and a crosslinked structure obtained by a vulcanizing agent or the like. In this elastomer composition, physical properties such as strength, durability, and heat resistance are improved without impairing flexibility and stretchability. This elastomer composition can be applied to various fields of application.

Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be interpreted in a limited manner based on the description of the examples.

(Preparation of peptide solution)
[Production Example 1]
In 2 L of water boiled and degassed, 30 g of potassium hydroxide (manufactured by Wako Pure Chemicals, reagent grade 1), 100 mL of alkylsulfonic acid surfactant (Charmy Christa manufactured by Lion), nonionic surfactant (Kao Corporation) Manufactured by Emulgen) and 20 g of sodium thiosulfate (manufactured by Wako Pure Chemicals, reagent grade 1) were mixed to obtain a treatment solution. To this treatment solution, 150 g of commercially available wool (wool) cut to a length of about 1 cm was added, followed by stirring at 60 ° C. for 120 hours to obtain the peptide solution of Production Example 1. This peptide solution is a brown solution containing a minute amount of fine particles. The physical properties of peptide P1 contained in this peptide solution are as follows.
Number average molecular weight (Mn): 8,000
Cystine content: 8.0% by mass
Amount of cystine bond: 8.0% by mass
Amount of thiol group: 0% by mass

[Production Example 2]
80 g of urea, 20 g of 2-mercaptoethanol and 10 g of sodium dodecyl sulfate were blended in 100 mL of pure water to obtain a treatment solution. To this treatment solution, 20 g of wool was added and stirred at 60 ° C. for 24 hours, and then the remaining insoluble particles were removed by dialysis to obtain the peptide solution of Production Example 2. The physical properties of peptide P2 contained in this peptide solution are as follows.
Number average molecular weight (Mn): 400,000
Cystine content: 8.0% by mass
Amount of cystine bond: 0% by mass
Amount of thiol group: 8.0% by mass

(Preparation of chlorinated natural rubber latex (CL-NRL))
1000 mL of commercially available high-ammonia natural rubber latex (rubber solid content concentration: 62% by mass), 500 mL of cleaning agent (containing 3% by mass of Fine Clean CL, sodium hypochlorite and potassium hydroxide manufactured by Tokyo Glass Machinery Co., Ltd.) Then, 40 mL of a nonionic surfactant (Emulgen 106 manufactured by Kao Corporation, concentration 25 mass%) and 400 mL of pure water were added and mixed. After adding 10% by mass of sulfuric acid so that the pH of the resulting mixed solution becomes weakly acidic (pH 6-7), the partially solidified suspended matter is removed, thereby chlorinated natural rubber latex (CL- NRL).

[Example 1]
5 mL of a commercially available high-ammonia natural rubber latex (zeta potential: −58.36 mV) prepared to a solid content concentration of 50% was mixed with 2 mL of the peptide solution of Production Example 1, and then stirred at room temperature (about 30 ° C.). Let stand for hours. Next, the entire amount of the obtained blended solution was poured into a tray having a bottom area of 24 cm ² and naturally dried at room temperature (about 30 ° C.) to obtain a sheet-like composition. The obtained sheet-like composition was washed with water and then naturally dried for 7 days to obtain the elastomer composition of Example 1. The amount of peptide P1 added to 100 parts by mass of the polymer (solid content) in the latex is 10 parts by mass.

[Example 2]
Except for adding 0.25 g of gluten (manufactured by Yutec Co., Ltd., for sugar-restricted food GOPAN) in 2.5 mL of water, and adding the total amount of this dispersion to 5 mL of natural rubber latex described in Example 1, The elastomer composition of Example 2 was obtained in the same manner as Example 1. The amount of gluten added to 100 parts by mass of the polymer (solid content) in the latex is 10 parts by mass.

[Comparative Example 1]
Comparative Example 1 was carried out in the same manner as in Example 1 except that 0.25 g of soy protein was dispersed in 2.5 mL of water, and then the total amount of this dispersion was added to 5 mL of natural rubber latex described in Example 1. An elastomer composition was obtained. The amount of soy protein added to 100 parts by mass of the polymer (solid content) in the latex is 10 parts by mass.

[Examples 3, 5, and 7 and Comparative Example 5]
The elastomer compositions of Examples 3 and 5 and Comparative Example 5 were obtained in the same manner as in Example 1 except that the polymers shown in Table 1-3 were used. In Example 7, dilute sulfuric acid was added so that the pH of the peptide solution of Production Example 1 was slightly acidic (pH 6-7), and then blended into the polymer latex shown in Table 2.

[Examples 4, 6, 8 and Comparative Example 6]
The elastomer compositions of Examples 4 and 6 and Comparative Example 6 were obtained in the same manner as Example 2 except that the polymers shown in Table 1-3 were used. In Example 8, dilute sulfuric acid was added so that the pH of the gluten dispersion became weakly acidic (pH 6-7), and then blended with the polymer latex shown in Table 2.

[Comparative Examples 2-4 and 7]
Elastomer compositions of Comparative Examples 2, 3 and 7 were obtained in the same manner as Comparative Example 1 except that the polymers shown in Table 1-3 were used. In Comparative Example 4, dilute sulfuric acid was added so that the pH of the soy protein dispersion became weakly acidic (pH 6-7), and then blended with the polymer latex shown in Table 2.

[Example 9]
After mixing and stirring 40 mL of the peptide solution of Production Example 1 in 100 mL of chloroprene rubber latex (CR650 manufactured by Showa Denko KK, zeta potential: 32.72 mV) prepared to a solid content concentration of 50%, room temperature (about 30 ° C.) And left for 12 hours. Next, the entire amount of the obtained blended solution was poured into a tray having a bottom area of 200 cm ² and naturally dried at room temperature (about 30 ° C.) to obtain a sheet-like composition. The obtained sheet-like composition was washed with water, and then naturally dried for 7 days to obtain an elastomer composition of Example 9. The amount of peptide P1 with respect to 100 parts by mass of the polymer (solid content) in the latex is 10 parts by mass.

[Comparative Example 8]
An elastomer composition of Comparative Example 8 was obtained in the same manner as in Example 9 except that pure water was used instead of the peptide solution of Production Example 1.

[Example 10]
1500 mL of the high ammonia natural rubber latex described above and 500 mL of chlorinated natural rubber latex (CL-NRL) were mixed to prepare a solid concentration of 50% by mass to obtain a mixed latex. After 200 g of this mixed latex was mixed with 200 g of the peptide solution of Production Example 1 and 200 g of a dispersion containing 10% by mass of gluten and 22.5 g of wax (HE-40 from Ipics, concentration 40% by mass) and stirred. And allowed to stand at room temperature (about 30 ° C.) for 12 hours. 100 ml of the obtained blended solution was poured into a tray having a bottom area of 200 cm ² and naturally dried at room temperature (about 30 ° C.) to obtain a sheet-like composition. The obtained sheet-like composition was washed with water and then naturally dried at room temperature (about 30 ° C.) to obtain the elastomer composition of Example 10. The amount of peptide P1 with respect to 100 parts by mass of the polymer (solid content) in the latex is 10 parts by mass.

[Comparative Example 9]
An elastomer composition of Comparative Example 9 was obtained in the same manner as in Example 10 except that pure water was used instead of the peptide solution of Production Example 1.

[Examples 11-12 and Comparative Example 10]
Elastomer compositions of Examples 11-12 and Comparative Example 10 were obtained in the same manner as in Example 1 except that the polymer and peptide formulations were as shown in Table 5.

(Manufacture of rubber balloons)
[Example 13]
A blending solution was prepared in the same manner as Example 10. Next, a balloon mold having a coagulating liquid (calcium nitrate aqueous solution having a concentration of 30% by mass) attached to the surface was prepared, and this balloon mold was immersed in an immersion tank into which the above-described blending solution was charged. The balloon mold pulled up from the immersion tank was allowed to stand at room temperature (about 30 ° C.) for 1 hour, and then the balloon mold was removed to prepare a rubber balloon made of the elastomer composition of Example 13.

[Example 14]
3000 mL of the above-mentioned high ammonia natural rubber latex and 1000 mL of chlorinated natural rubber latex (CL-NRL) were mixed and prepared so as to have a solid content concentration of 50% by mass to obtain a mixed latex. The mixed latex of 4000 mL was mixed with 200 g of the peptide solution of Production Example 1 and 200 g of a dispersion containing 10% by mass of gluten and 22.5 g of the wax described above, and then stirred, and then further blue-based coloring compound (manufactured by Dainichi Seika Co., Ltd.). 6 g of blue pigment and titanium oxide). Thereafter, a rubber balloon made of the elastomer composition of Example 14 was prepared in the same manner as in Example 13 using the compounded liquid obtained by allowing to stand at room temperature (about 30 ° C.) for 12 hours. The amount of peptide P1 with respect to 100 parts by mass of the polymer (solid content) in the latex is 10 parts by mass.

[Comparative Example 11]
A commercially available rubber balloon obtained by vulcanizing a rubber composition containing natural rubber as a base rubber was used as a rubber balloon made of the elastomer composition of Comparative Example 11.

[Heat-resistant]
Two test pieces each were collected from an elastomer composition having a thickness of about 1 mm. Two test pieces stacked so as to cross each other were covered with aluminum foil and heated with a hair iron (Tiny manufactured by Koizumi). The state of the test piece after heating at 160 ° C. for 3 minutes was observed and judged according to the following criteria. The results obtained for the elastomer compositions of Examples and Comparative Examples are shown in Table 1-5 below.
G: No deformation or fusion of the test piece.
NG: The test piece was deformed or fused.

[Tensile test]
Using a punching blade defined in JIS K6250 “Rubber-General physical test method”, an elastomer composition, a rubber balloon, and a polymer dumbbell-shaped No. 3 type test piece were prepared. Using the obtained test piece, a tensile test was performed in accordance with the test method described in JIS K6251 “Vulcanized rubber and thermoplastic rubber—How to obtain tensile properties”. The 300% modulus (MPa), the breaking strength (%), and the breaking elongation (MPa) obtained for the elastomer compositions of Examples and Comparative Examples are shown in the following Table 1-5 as ME ₃₀₀ , Tb, and Eb, respectively. Has been. The 300% modulus (MPa) obtained for the polymer is shown in Table 1-5 below as MP ₃₀₀ . The results obtained for the specimens taken from the rubber balloons are shown in Table 6 below.

[Hardness measurement]
In accordance with JIS K6253 “Vulcanized Rubber and Thermoplastic Rubber—How to Determine Hardness”, each of 1.5 mm thick test pieces was prepared from the elastomer compositions of Examples 9-10 and Comparative Example 8-9. Four pieces were collected. After stacking the four test pieces, the hardness of the elastomer composition was measured by pressing an Asker Durometer Type A (Polymer Keiki Co., Ltd.). Table 7 below shows the result of calculating the average value of five points from the seven measurement values obtained by changing the measurement position, excluding the maximum value and the minimum value.

[Usage feeling]
Ten testers were allowed to use the rubber balloons of Examples 13 and 14 and Comparative Example 11 to hear the feeling of use. Based on the number of users who answered “soft” or “easy to inflate”, the following rating results are shown in Table 6 below.
A: 9 people or more B: 6-8 people C: 5 people or less

Details of the compounds shown in Table 1-5 are as follows.
HA-NRL: Commercially available high ammonia natural rubber latex (Zeta potential: -58.36 mV)
CRL ⁽¹⁾ : Chloroprene rubber latex (CR350 manufactured by Showa Denko KK, zeta potential: 32.72 mV)
CRL ⁽²⁾ : Chloroprene rubber latex (CR650 manufactured by Showa Denko KK, zeta potential: 32.72 mV)
CL-NRL: Chloride natural rubber latex (Zeta potential: 50.36 mV)
NBRL: carboxylated modified acrylonitrile-butadiene rubber latex (LX550 manufactured by Nippon Zeon Co., Ltd., zeta potential: 47.31 mV)
IRL: Isoprene rubber latex (Cariflex IR0401, zeta potential: 19.47 mV)
P1: Peptide of Production Example 1 P2: Peptide of Production Example 2 GT: Gluten SB: Soy protein

As shown in Table 1-5, the elastomer compositions of the examples are superior in heat resistance, stretchability and flexibility as compared with the elastomer compositions of the comparative examples. Furthermore, as shown in Table 6, in the examples, higher evaluations are obtained for the feeling of use than in the comparative examples. From this evaluation result, the superiority of the present invention is clear.

The elastomer composition described above can be used in various fields such as medical supplies, hygiene products, and cosmetic products.

Claims

A peptide containing 4.0% by mass or more and 30% by mass or less of cystine, a halogen group, a sulfone group, a carbonyl group, an amino group, an imino group, a carboxyl group, a hydroxyl group, a sulfide group, a disulfide group, a sulfonyl group, an amide group, and Comprising as a main component a polymer having at least one polar group selected from the group consisting of nitrile groups,
Having a cross-linked structure formed based on electrostatic interaction and hydrophobic effect between the peptide and the polymer,
An elastomer composition having a 300% modulus ME 300 smaller than the 300% modulus MP 300 of the polymer.
The elastomer composition according to claim 1, wherein 300% modulus ME 300 of the elastomer composition is 0.1 MPa or more and 1.0 MPa or less.
The elastomer composition according to claim 1 or 2, wherein the elastomer composition has a breaking strength Tb of 0.1 MPa or more and 6.5 MPa or less.
The elastomer composition according to any one of claims 1 to 3, wherein the polymer has an absolute value of zeta potential of 30 mV or more.
The elastomer composition according to any one of claims 1 to 4, wherein the polymer is natural rubber that has not been deproteinized.
The elastomer composition according to any one of claims 1 to 5, comprising 1.0 to 20 parts by mass of the peptide with respect to 100 parts by mass of the polymer.
The elastomer composition according to any one of claims 1 to 6, substantially free of a vulcanizing agent, a vulcanization accelerator, and a vulcanization acceleration aid.
The elastomer composition according to any one of claims 1 to 7, wherein the peptide contains 5.0% by mass or more and 15% by mass or less of a cystine bond.
The elastomer composition according to any one of claims 1 to 8, wherein the amount of the thiol group contained in the peptide is 1.0% by mass or less.
10. The elastomer composition according to claim 1, wherein the peptide is fine particles insoluble in water, and the fine particles have an average particle size of 0.1 μm or more and 1.0 μm or less.
A peptide containing 4.0% by mass or more and 30% by mass or less of cystine, a halogen group, a sulfone group, a carbonyl group, an amino group, an imino group, a carboxyl group, a hydroxyl group, a sulfide group, a disulfide group, a sulfonyl group, an amide group, and A first step of obtaining a mixture by mixing a polymer having at least one polar group selected from the group consisting of nitrile groups in an aqueous medium;
The mixed solution is dried to form a crosslinked structure based on electrostatic interaction and hydrophobic effect between the polymer and the peptide, so that 300% modulus ME 300 is 300% of the polymer. And a second step of obtaining an elastomer composition smaller than the modulus MP 300 .