JP2014074112A - Elastomer molded article having no or reduced amount of zinc oxide and elastomer product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an elastomer and a glove having no or a reduced amount of metal ion such as zinc oxide while maintaining practical basic performance (a tensile property and flexibility).SOLUTION: There is provided a glove as an elastomer molded article having a crosslinkage by a covalent bond by a dihydrazide compound, or a crosslinkage selected from a crosslinkage by an ion bond by metal ions and the crosslinkage by the covalent bond by the dihydrazide compound, between carboxyl groups of carboxylated acrylonitrile-butadiene elastomer containing acrylonitrile of 20 to 40 wt.% and an unsaturated carboxylic acid of 4 to 8 wt.%.

Description

TECHNICAL FIELD The present invention relates to a copolymer latex for dip molding, a dip molding composition, and a dip molded product, which is a thin elastomer that does not contain zinc oxide or has a reduced zinc oxide content that has been used as a metal crosslinking agent. Regarding gloves.

Thin elastomer gloves made of nitrile butadiene rubber (also referred to as NBR) are widely used for various industrial and medical purposes such as housework, food industry, electronic component manufacturing, pharmaceutical industry, inspection, and experiment. Has been.
The basic performance required for thin elastomeric gloves is that it is not easily torn during wearing (high breaking strength), has little resistance when moving fingers, and does not get tired even if worn for a long time (soft It must be easy to grow). Furthermore, in work handling chemicals such as oils and organic solvents such as automobile factories and semiconductor cleaning processes, they are highly resistant to the permeation of these chemicals and should not be easily weakened even when contacted. (Chemical resistance) is required.
Despite active research, the goal has not been achieved, and research and development are in progress.

A glove based on carboxylated acrylonitrile butadiene has been used as a thin glove for medical use or clean room use. When cross-linking carboxylated acrylonitrile butadiene, various measures have been taken such as reducing the amount of sulfur used by cross-linking between butadienes with sulfur and cross-linking between carboxyl groups with zinc. For example, US Pat. No. 5,014,362 (Cited document 1) is a method for crosslinking carboxylated nitrile rubber by using zinc oxide and sulfur. Typical carboxylated nitrile rubber consists of segments consisting of acrylonitrile, butadiene and organic acids formed in various proportions. By using sulfur and vulcanization accelerators, covalent crosslinks can be formed in the butadiene sub-segments. In addition, an ion bond can be generated in the carboxylated acrylonitrile (organic acid) portion by using a metal oxide such as zinc oxide and other metal salts.
To increase strength and chemical resistance, it can be crosslinked by two different mechanisms. The first crosslinking mechanism is to crosslink carboxyl groups with polyvalent metal ions by ionic bonds. Ionic bonding generally adds zinc oxide to the emulsion. The stiffness / flexibility of the polymer is susceptible to this type of crosslinking. The other crosslinking mechanism is covalent crosslinking of the butadiene portion of the polymer with sulfur and a catalyst known as a vulcanization accelerator. This covalent cross-linking is particularly important for increasing chemical resistance. Often manufactured by first applying a coagulation liquid (often calcium nitrate) to a ceramic former, dipping in a nitrile latex, and locally gelling the nitrile rubber on the surface of the mold.

Carboxylated nitrile rubber, which is a copolymer of acrylonitrile, butadiene, and unsaturated carboxylic acid, can form ionic bonds by the presence of zinc and carboxyl groups. However, it is difficult to form a covalent bond with a compound containing zinc, and as a method for compensating for the defect by crosslinking of zinc using a small amount of added sulfur, JP 2002-527632 A (Patent Document 2) A glove is described in which carboxylated nitrile rubber, a copolymer of acrylonitrile, butadiene and unsaturated carboxylic acid, is crosslinked with 1 to 3 phr sulfur and 0.5 phr polyvalent metal oxide.
In US Pat. No. 6,673,871 (Patent Document 3), a metal oxide composed of zinc oxide or the like is used for elastomer products such as gloves without using a sulfur-containing crosslinking agent or vulcanization accelerator. It describes use as a crosslinking agent. Japanese Patent Application Laid-Open No. 2004-526063 (Patent Document 3), which is a corresponding Japanese patent, is obtained by crosslinking the synthetic elastomer without using an accelerator, consisting essentially of a metal oxide, and having sulfur substitution. The synthetic elastomer is crosslinked and cured at a temperature of 85 ° C. or lower using a crosslinking agent.
JP-A-2008-545814 (Patent Document 4) describes (a) 0.25 to 1.5 parts of zinc oxide per 100 parts of dry rubber, an alkali for adjusting the pH to about 8.5 or more, and stable Creating a carboxylated nitrile butadiene compounded rubber composition comprising an agent and one or more accelerators selected from the group comprising guanidine and dithiocarbamate and optionally a thiazole compound; and (b) said carboxyl An elastomer article comprising the steps of: immersing a former in a nitrile butadiene compounded rubber composition; and (c) curing the carboxylated nitrile butadiene compound rubber composition to form the elastomer article. Crosslink with zinc oxide. A combination of vulcanization accelerators is included to ensure that the product possesses the desired degree of chemical resistance. Dithiocarbamate is used as a vulcanization accelerator. A higher effect can be obtained by using a mixture of dithiocarbamate vulcanization accelerator, diphenylguanidine and zinc mercaptobenzothiazole to improve resistance to chemical substances. This means that sulfur and vulcanization accelerators are used for rubber cross-linking, and the gloves thus produced have the problem of causing type 4 hypersensitivity.
In U.S. Pat. No. 7,0054,78 (Patent Document 5), when obtaining a product comprising an elastomer, the elastomer having a carboxyl group contains (a) a carboxylic acid or a derivative thereof, and (b) a divalent or trivalent metal. The reaction is carried out in a state containing a compound and (c) an amine or amino compound, and (d) a neutralizing agent that neutralizes at least a part of the carboxyl groups in the base polymer. At this time, a vulcanization accelerator, thiuram, and carbamate are not used. Examples of the base polymer include natural latex rubber and synthetic latex polymer (such as acrylonitrile), butadiene rubber such as synthetic butadiene rubber and carboxylated butadiene rubber, but does not contain MMA. Nor is carboxylated acrylonitrile used. In this method, the (c) amine or amino compound is an essential component. It reacts with an amine group or amino group and a carboxylic acid derivative to form a complex with a divalent or trivalent metal. It has been pointed out that it is difficult to stabilize in terms of using a complexing reaction, and as a result, it is difficult to obtain a stable product.

The inventors have studied the use of metal oxides centered on zinc oxide in order to crosslink without using sulfur as a crosslinking agent. Acrylonitrile, butadiene, and carboxylic acid elastomers crosslinked using zinc oxide as a crosslinking agent cannot obtain sufficient properties in terms of strength. When zinc oxide is used as a cross-linking agent, it is not sufficient in terms of strength and the like, so it is necessary to use a combination of other cross-linking agents and cross-linking accelerators. Even if it is a small amount, when it is used in combination with sulfur as a crosslinking agent and a crosslinking accelerator as a sulfur compound, it may cause delayed type 4 hypersensitivity. It is desirable to avoid using certain crosslinking accelerators. For this reason, it is required to use a new cross-linking agent of a compound that does not cause delayed type 4 hypersensitivity. In addition to divalent metal oxides such as zinc oxide as a cross-linking agent, as a new cross-linking means for cross-linking acrylonitrile, butadiene and carboxylic acid elastomers, basic performance is achieved by cross-linking already self-cross-linked carboxylated acrylonitrile butadiene with zinc ions. Developed a thin elastomeric glove that satisfies the requirements. This is described in WO2011 / 068394 (patent document 6) and two patent applications have been filed (WO2012 / 943893: patent document 7, WO2012 / 043894: patent document 8). This glove does not contain a vulcanization crosslinking accelerator, does not show a positive reaction in the skin irritation test (translated term Dermal Sensitization Study), meets the FDA low skin irritation criteria, and may cause allergies Compared to conventional gloves using sulfur bridges.

Carboxylated acrylonitrile butadiene is used as a raw material, polymerized by self-crosslinking (crosslinking by a crosslinkable reactive group) instead of sulfur crosslinking, and the carboxyl groups are crosslinked with zinc ions (using zinc oxide as a crosslinking agent). Gloves cross-linked by this cross-linking method are evaluated in terms of preventing allergies and preventing contamination with metal ions or metals. It has been found that gloves cross-linked by the above-mentioned cross-linking method have a problem that when they get wet with sweat or water, the strength is reduced and they are easily broken, and the durability characteristics are lowered (reduced durability).
As a result of investigating the cause of the decrease in Durability, the binding by zinc ions is replaced by sodium ions and hydrogen ions, and the cross-linked portion is cleaved, and the zinc ions separated from the glove are eluted. It was found that the object to be treated (manufactured product) was contaminated by the eluted metal such as zinc, which was sometimes regarded as a problem.

It is necessary to provide a glove that has improved the above points, specifically, a glove that does not easily decrease in strength even when it gets wet with water, and a glove in which the means for cross-linking is not easily decomposed with respect to cross-linking that causes a decrease in strength. It becomes. In these gloves, it goes without saying that the basic physical properties (elongation and breaking strength) of the gloves are required to maintain conventional characteristics.

If it is established that the cross-linked part of a commercialized rubber glove is not easily disassembled, it will be a solution. It was examined whether it can be found in the conventional invention that the cross-linked portion is difficult to be decomposed. In conventional examples, gloves that maintain and improve strength can be considered. Therefore, it is necessary to examine whether such a glove has the property of being difficult to be decomposed at the cross-linked portion of the intended rubber glove. did.
Although the results show that there is a glove that maintains and improves strength, it was not possible to find a glove having a property that the crosslinked portion of the rubber glove is difficult to be decomposed. The specific contents are as follows.

For applications such as seals, belts or rolls, the compression set of the product is required to be even smaller, and when used in applications such as belts and rolls, it is required as a physical property that the amount of dynamic heat generation is small. . As a composition therefor, it is obtained through a step of coagulating a latex of copolymer rubber with a coagulant aqueous solution, and the α, β-ethylenically unsaturated nitrile monomer unit content is 10 to 60% by weight and the iodine value is 120. A carboxyl group-containing nitrile rubber (A) having a total content of magnesium, calcium and aluminum of 2,000 ppm by weight or less, and the carboxyl group-containing nitrile rubber (A) and a crosslinking agent (B) There is an invention comprising a nitrile rubber composition comprising Preferably, the amount of carboxyl group of the nitrile rubber (A) is 5 × 10 ^{−4 to} 5 × 10 ⁻¹ ephr, and preferably the carboxyl group is a structural unit of the carboxyl group-containing nitrile rubber (A). There is an invention using a monoalkyl ester monomer having an ethylenically unsaturated dicarboxylic acid (re-referenced 2007-096551, cited reference 9). Carboxyl group-containing nitrile rubber (A) whose total content of magnesium, calcium and aluminum is 2,000 ppm by weight or less, and the carboxyl group-containing nitrile rubber (A) and a crosslinking agent (B) ), But not a cross-linking agent that prevents hydrolysis. It is intended to maintain strength and does not mention that the cross-linked portion of the product is hydrolyzed and means for preventing it.

A dip molding die having an organic peroxide activator and a coagulant adhering to the surface is immersed in and removed from a dip molding composition containing a conjugated diene rubber latex and a water-insoluble organic peroxide. Then, a dip molded product obtained by crosslinking the conjugated diene rubber by heating, and a dip molded product obtained in the same manner as described above except that it is added to the conjugated diene latex instead of being attached to the activator dip molding die. These dip-molded articles are inventions that do not have a sulfur odor and are excellent in tensile strength and bending fatigue resistance (Recited 2007-049651 Citation 10). Although the use of an organic peroxide activator as a crosslinking agent is described as a crosslinking means, it does not specifically describe preventing the crosslinked portion from being easily hydrolyzed.
Using a carboxylic acid-modified nitrile copolymer latex produced with an unsaturated monomer having a crosslinkable functional group selected from vinyl groups and epoxy groups, and performing a long stirring and aging step In addition, an invention capable of producing a molded article having high oil resistance, mechanical strength, and good texture that does not cause an allergic reaction due to sulfur and a vulcanization accelerator (Japanese Patent Laid-Open No. 2010-144163). The invention uses an unsaturated monomer having a crosslinkable functional group selected from a vinyl group and an epoxy group. The invention does not fall under an invention that describes a means for making it difficult for a crosslinked part of a commercialized rubber glove to be decomposed.
A copolymer latex for dip molding having high polymerization stability, a dip molding composition having good mechanical stability and salt coagulation property, and a dip molded product having excellent physical properties such as texture, tensile strength, elongation, etc. , 3-butadiene 30-80% by weight, acrylonitrile 15-50% by weight, ethylenically unsaturated carboxylic acid monomer 0.1-10% by weight and other ethylenically unsaturated monomers copolymerizable therewith A copolymer latex obtained by emulsion polymerization of a monomer comprising 0 to 54.9% by weight, wherein the amount of particle-bound acid is A (meq / g) and the amount of particle-unbound acid is B (meq / g). ), A copolymer latex for dip molding characterized by satisfying 0.05 ≦ B / A ≦ 0.5 (Japanese Unexamined Patent Publication No. 2009-197149, cited document 12).
This invention does not fall under the invention that states that the cross-linked portion of a commercialized rubber glove has been subjected to a measure that is difficult to be decomposed.
A nitrile rubber composition, a product produced from the composition, and a method of making the same, the step of combining the nitrile latex with a stabilizer, and adjusting the pH of the nitrile latex from about 8.5 to 10.0 Forming a nitrile rubber composition by contacting the basic nitrile latex with a substantially zinc-free crosslinker and at least one accelerator to form a nitrile rubber composition. A method for preparing a nitrile rubber composition (Japanese Patent Laid-Open No. 2000-512684, cited reference 13), in which the rubber composition is substantially zinc oxide, is known.
This invention is also not an invention based on the premise that the cross-linked portion of a commercialized rubber glove is imparted with a property that is difficult to be decomposed.
A polymer latex made by radical emulsion polymerization comprising polymer particles containing structural units derived from at least one conjugated diene component, the polymer particles having a glass transition temperature (Tg) of at least 50 ° C. At least one hard phase portion and at least one soft phase portion having a glass transition temperature (Tg) of at most 10 ° C., wherein the total amount of hard phase portion is from 2 to 40% by weight relative to the total weight of the polymer particles Yes, the total amount of soft phase portion is 60-98 wt%, (Tg) is measured by DSC according to ASTM D3418-03, and the polymer latex is electrolyte stability measured as a critical coagulation concentration (0. measuring the total solids content of 1% latex) is less than 30 mmol / CaCl _2, particularly suitable port for the production of dip-molded articles Invention is a mer latex (JP 2008-512526 JP Patent Document 14) are known. It is.
This invention also does not fall under the invention based on the premise that the cross-linked portion of the manufactured rubber glove is not easily decomposed.

From the above, it has been found that the invention of a commercialized rubber glove pursuing the invention based on the premise of the property that the crosslinked part of the commercialized rubber glove is not easily decomposed has not been found so far. Also, rubber gloves have many inventions that require flexibility. It was an invention of a rubber glove that pursues flexibility, and at the same time, it was decided to investigate a rubber glove that was made difficult to disassemble at the cross-linked portion of a commercialized rubber glove.

There are methods of blending softeners such as process oil and plasticizers such as phthalic acid esters and adipic acid esters into NBR. It is necessary to use a large amount of a liquid softener or plasticizer, which may cause so-called bleeding that oozes out on the surface of an NBR glove, and may be slippery when used for work that gets wet with water (special No. 2005-54328 (Patent Document 15).
As an attempt to improve this, Japanese Patent Application Laid-Open No. 2000-290814 (Patent Document 16) and Japanese Patent Application Laid-Open No. 2007-231428 (Patent Document 17) include NBR latex, acrylonitrile and (meth) acrylic acid as softening agents. A work glove characterized by forming a film using an NBR compound blended with a copolymer with an alkyl acrylate as a material is disclosed. This invention is disadvantageous in that the compatibility between the NBR and the softening agent may be insufficient, and the cost is increased. Japanese Patent Application Laid-Open No. 2002-309043 (Patent Document 18) discloses a method of adding 3 to 30 parts by weight of phenyl alkyl sulfonate to 100 parts by weight of rubber. There are also problems of compatibility and high cost. Japanese Patent Application Laid-Open No. 2005-054328 (Patent Document 19) discloses a method of imparting flexibility by adding an oil derived from a natural product to NBR latex, but the problem of bleeding cannot be avoided.
Although there are inventions that improve flexibility in rubber gloves, additives are required to obtain flexibility, and means such as crosslinking and means for improving flexibility are used to improve the invention. We could not find a conventional example of doing it.

Although cross-linking with metal ions such as zinc has been evaluated in terms of preventing allergies and preventing contamination with metal ions and metals, gloves cross-linked by this cross-linking method are When it gets wet, there is a problem that the strength decreases and it is easy to break, and the durability property deteriorates.When the cause is investigated, the bond by zinc ion is replaced by sodium ion or hydrogen ion, and it is cut at the crosslinked part. As a result, the zinc ions separated from the gloves will be eluted, which will contaminate the object to be treated (the product being manufactured) by the metal such as zinc, and the metal ions such as zinc. Invented a new cross-linking means in which the cross-linked portion does not decompose, and the basic physical properties (elongation and breaking strength) maintain the conventional characteristics, and are flexible. Invention of a material having a characteristic that there is a gender is desired.

US Pat. No. 5,014,362 Japanese translation of PCT publication No. 2002-527632 US Pat. No. 6,673,871 JP 2008-545814 A US Patent No. 7,005478 WO2011 / 068394 WO2012 / 943893 WO2012 / 043894 No. 2007-049651 No. 2007-049889 JP 2010-144163 A JP 2009-197149 A JP 2000-512684 A JP 2008-512526 A JP 2005-54328 A JP 2000-290814 A JP 2007-231428 A JP 2002-309043 A JP 2005-054328 A

  The problems to be solved by the invention are that the ratio of the three components of acrylonitrile, butadiene and unsaturated carboxylic acid constituting the carboxylated acrylonitrile butadiene elastomer is hard to break during wearing (high breaking strength), and when moving a finger Resistant to low resistance, satisfying that hands will not get tired even if worn for a long time (soft and easy to stretch), strong resistance to permeation of chemicals, and not easily weakened even when contacted (Chemical resistance) is specified so that the carboxylated acrylonitrile butadiene elastomer is related to the conventionally used cross-linking agent composed of zinc ions and does not contain metal ions such as zinc ions or metal ions such as zinc ions. Revealing novel cross-linking agents that reduce content, even in the presence of sweat and moisture Solution is not easily crosslinked elastomer (hereinafter, elastomer molded product) is to provide a thin glove with and elastomers.

It has been found that the problem to be solved by the invention can be solved by the following.
(1) Carboxylated acrylonitrile butadiene elastomer employs one containing 20 to 40% by weight of acrylonitrile and 4 to 8% by weight of unsaturated carboxylic acid, and is newly covalently bonded with a dihydrazide compound between the carboxyl groups of the acrylonitrile butadiene elastomer. By forming a cross-link selected from the cross-linking by ionic bond by metal ion or the cross-linking by covalent bond by dihydrazide compound, the conventional metal ion is not used at all, or the amount of metal ion used is conventionally In comparison with the dihydrazide compound, by using a dihydrazide compound, it is produced by a dip method using an elastomer molded product in which a crosslink that is difficult to be decomposed even in the presence of water or sweat is formed. Gloves are intended. , Making it difficult to tear while wearing (strong breaking strength), reducing the resistance applied to the finger when moving the finger, satisfying that the hand does not get tired even if worn for a long time (soft and easy to stretch) In addition, it has a property that satisfies the resistance to permeation of these chemicals and that it does not easily become brittle even when contacted (chemical resistance). The present invention has been completed by finding that the glove can be prevented from being decomposed by setting the amount of metal ion used to be low so that there is no metal ion causing decomposition.
(2) In the case of (1) above, when a carboxylated acrylonitrile butadiene elastomer having a Mooney viscosity (ML _{(1 + 4)} (100 ° C.)) of 100 to 220 is used, the carboxyl group of the carboxylated acrylonitrile butadiene elastomer In the meantime, a crosslinking selected from a covalent crosslinking by a dihydrazide compound, or a crosslinking by an ionic bond by a metal ion and a crosslinking by a covalent bond by a dihydrazide compound is formed. No crosslinking is performed between butadienes. As a result, it is possible to obtain a glove which is an elastomer molded product having no practical problem even if sulfur crosslinking is not performed between butadienes which have been generally performed. Since sulfur and a vulcanization accelerator are not used for cross-linking, a glove that hardly causes type IV allergy can be obtained.
(3) In the case of (1) above, the Mooney viscosity (ML _{(1 + 4)} (100 ° C.)) of 40 to 100 is shared by the dihydrazide compound between the carboxyl groups of the carboxylated acrylonitrile butadiene elastomer. A crosslink selected from a crosslink by a bond or a crosslink by an ionic bond by a metal ion and a crosslink by a covalent bond by a dihydrazide compound is formed, and a crosslink by a covalent bond by sulfur is formed between butadienes. As a result, metal ions that have been conventionally used are not used at all, or the amount of metal ions used can be reduced, so that the value can be made lower than in the past. A strength with no practical problems was obtained.
(4) The above-mentioned (2) carboxylated acrylonitrile elastomer (referred to as Elastomer A) 95 to 70% by weight, acrylonitrile 20 to 50% by weight and butadiene 50 to 80% by weight (total 100% by weight), and the weight average molecular weight (Polystyrene conversion value) The following treatment is adopted for an elastomer mixture composed of 5 to 30% by weight of an acrylonitrile butadiene elastomer (referred to as elastomer B) of 7,000 to 50,000.
For the elastomer A, a crosslinking selected from a covalent bond by a dihydrazide compound or a bridge by an ionic bond by a metal ion and a crosslink by a covalent bond by a dihydrazide compound is formed between carboxyl groups, and no crosslinking is performed between butadienes. Even if butadiene which has been generally used is not subjected to sulfur cross-linking, an elastomer-formed product having a practically no problem can be obtained. Without using sulfur and a vulcanization accelerator for crosslinking, it is possible to obtain an elastomer molded product that hardly causes type 4 allergy. An elastomer molded product excellent in flexibility can be obtained by adding the elastomer B, and in a glove which is an elastomer molded product manufactured using the elastomer B, the elastomer B functions as a softening agent.
By using the elastomer B, it does not cause bleeding, which is seen when a conventional softener or plasticizer is used. Overall, sulfur and vulcanization accelerators are not used in crosslinking, and therefore it is difficult to cause type 4 allergy.
(5) Carboxylated acrylonitrile elastomer (referred to as Elastomer A) 95 to 70% by weight of the above (3), acrylonitrile 20 to 50% by weight and butadiene 50 to 80% by weight (total 100% by weight), and weight average molecular weight (Polystyrene conversion value) The following treatment is adopted for an elastomer mixture composed of 5 to 30% by weight of an acrylonitrile butadiene elastomer (referred to as elastomer B) of 7,000 to 50,000.
For Elastomer A, a cross-linking selected from a covalent bond by a dihydrazide compound or a cross-link by an ionic bond by a metal ion and a cross-link by a covalent bond by a dihydrazide compound is formed between carboxyl groups, and a cross-linking by a covalent bond by sulfur between butadienes. Form.
The conventional metal ion is not used at all, or the amount of metal ion used can be reduced to a lower value than before, there is no problem in practical strength, and it is flexible by adding elastomer B. A glove which is an elastomer molded product having excellent properties could be obtained. This is because the elastomer B acts as a softening agent.
By using the elastomer B, bleeding does not occur when a conventional softener or plasticizer is used.
(6) When a thin glove is produced according to the present invention, the glove is produced by employing the dip method using the elastomer molded product of (4) and (5). Specifically, it is as follows. An emulsion composition containing an elastomer composed of elastomer A and elastomer B, a pH adjuster and a cross-linking agent is prepared. A former (ceramic hand mold) is immersed in the emulsion composition to adhere an elastomer to the surface of the former, and after drying and heat treatment, the cross-linked gloves are pulled away from the former and collected. The zinc content of the glove thus obtained was 0.4% by weight (Examples 1 and 2), 0.0% by weight (Example 3) (Comparative Example 2 was 0.82% by weight, Comparative Example 3) In this case, it was 0.88 wt% (see Table 4 described later).

(1) The elastomer composition of the present invention and the elastomer glove which is an elastomer molded product obtained from the elastomer composition do not contain metal ions such as zinc ions in the used crosslinking agent, or the content of metal ions is reduced. Therefore, when it gets wet with sweat or moisture in the environment of use, it can be prevented from being broken, and other harmful effects caused by metal ions, for example, the metal ions released by the product handled by the operator It can prevent contamination, prevent the development of metal allergy, and can have break strength, flexibility and chemical resistance suitable for practical use.
(2) In the above (1), when a carboxylated acrylonitrile butadiene elastomer having a Mooney viscosity (ML _{(1 + 4)} (100 ° C.)) of 100 to 220 is employed, a dihydrazide compound between carboxyl groups of the carboxylated acrylonitrile butadiene elastomer To form a cross-link selected from a cross-link by a covalent bond or a cross-link by an ionic bond by a metal ion and a cross-link by a covalent bond by a dihydrazide compound. No crosslinking is performed between butadienes. In this case, it is not necessary to use sulfur and a vulcanization accelerator. As a result, the cross-linking agent used does not contain metal ions such as zinc ions, or the content of metal ions is reduced, so that it easily breaks when wet with sweat, moisture, etc. in the usage environment. Suitable for practical use, such as prevention of adverse effects caused by other metal ions, for example, prevention of contamination of products handled by workers with free metal ions, prevention of metal allergy It is possible to obtain an elastomer molded article and an elastomer glove that have high breaking strength, flexibility and chemical resistance and are less likely to cause type IV allergy.
(3) In the above (1), when a carboxylated acrylonitrile butadiene elastomer having a Mooney viscosity (ML _{(1 + 4)} (100 ° C.)) of 40 to 100 is employed, the carboxyl group of the carboxylated acrylonitrile butadiene elastomer is between Forms a crosslinking selected from a covalent bond with a dihydrazide compound, or a crosslink with an ionic bond with a metal ion and a covalent bond with a dihydrazide compound, and uses sulfur and a vulcanization accelerator between the butadienes to crosslink with sulfur. I do.
As a result, the cross-linking agent used does not contain metal ions such as zinc ions, or the content of metal ions is reduced, so that it easily breaks when wet with sweat, moisture, etc. in the usage environment. This can prevent other adverse effects caused by other metal ions, for example, contamination of the product handled by the operator with free metal ions.
(4) The above-mentioned (2) carboxylated acrylonitrile elastomer (referred to as Elastomer A) 95 to 70% by weight, acrylonitrile 20 to 50% by weight and butadiene 50 to 80% by weight (total 100% by weight), and the weight average molecular weight (Polystyrene conversion value) The following treatment is adopted for an elastomer mixture composed of 5 to 30% by weight of an acrylonitrile butadiene elastomer (referred to as elastomer B) of 7,000 to 50,000.
For the elastomer A, a crosslinking selected from a covalent bond by a dihydrazide compound or a bridge by an ionic bond by a metal ion and a crosslink by a covalent bond by a dihydrazide compound is formed between carboxyl groups, and no crosslinking is performed between butadienes. In the elastomer glove which is the elastomer composition and the elastomer molded product of (2), the elastomer B coexists so that the elastomer B acts as a softening agent, so that flexibility can be imparted. It does not cause bleeding, which is seen when using conventional softeners and plasticizers. As a whole, since sulfur and vulcanization accelerator are not used at the time of crosslinking, it has a characteristic that it is difficult to cause type IV allergy.
(5) 95 to 70% by weight of the carboxylated acrylonitrile elastomer (referred to as elastomer A) in the uncrosslinked state of (3), 20 to 50% by weight of acrylonitrile and 50 to 80% by weight of butadiene (total 100% by weight) The following treatment is employed for an elastomer mixture comprising 5 to 30% by weight of an acrylonitrile butadiene elastomer (referred to as elastomer B) having a weight average molecular weight (polystyrene conversion value) of 7,000 to 50,000.
For the elastomer A, a crosslink selected from a covalent bond by a dihydrazide compound or a crosslink by an ionic bond by a metal ion and a crosslink by a covalent bond by a dihydrazide compound is formed between the carboxyl groups, and the butadiene is crosslinked by sulfur. . In the elastomer glove using the elastomer molded product of (3), the elastomer B coexists, so that the elastomer B acts as a softening agent, so that flexibility can be imparted. It does not cause bleeding, which is seen when using conventional softeners and plasticizers.
(6) In the present invention, examples are shown for the cases (4) and (5), and a glove obtained by adopting a dip method using an elastomer is a former (ceramic hand) in the emulsion composition. The mold is soaked to attach the elastomer to the surface of the former, and after drying and heat treatment, the cross-linked gloves are pulled away from the former and collected. The zinc content of the glove thus obtained was 0.4% by weight (Examples 1 and 2), 0.0% by weight (Example 3) (Comparative Example 2 was 0.82% by weight, Comparative Example 3) In this case, it was 0.88 wt% (see Table 4 described later).

  The raw material to be treated in the present invention is a carboxylated acrylonitrile butadiene elastomer, and is composed of three components of acrylonitrile, butadiene and unsaturated carboxylic acid.

The carboxylated acrylonitrile butadiene elastomer comprises an amount of 4-8%, preferably 4-6% by weight of its weight of unsaturated carboxylic acid residues.
If the amount of the unsaturated carboxylic acid residue is less than the lower limit, crosslinking formation by a divalent metal ion described later is not sufficient, and if the upper limit is exceeded, excessive crosslinking is formed, resulting in a decrease in physical properties of the final product, a rubber glove. Lead. As the unsaturated carboxylic acid, acrylic acid and / or methacrylic acid (hereinafter referred to as “(meth) acrylic acid”) is used, and methacrylic acid is preferably used. The amount of the unsaturated carboxylic acid residue can be determined by quantifying the carboxyl group and the carbonyl group derived from the carboxyl group by infrared spectroscopy (IR) or the like.

  The remainder of the carboxylated acrylonitrile butadiene elastomer is a butadiene residue and a crosslinked structure. As the butadiene, 1,3-butadiene is preferable. The amount of the butadiene residue is 52 to 76% by weight, preferably 56 to 74% by weight, based on the total of the butadiene residue, the acrylonitrile residue and the unsaturated carboxylic acid residue. When the amount of the butadiene residue is within the range, a final product having excellent physical properties can be obtained.

  The carboxylated acrylonitrile butadiene elastomer is obtained by emulsion polymerization of acrylonitrile, (meth) acrylic acid, 1,3-butadiene and, if necessary, other unsaturated monomers for forming a crosslinked structure or the like according to a conventional method. Can be prepared. In emulsion polymerization, commonly used emulsifiers, polymerization initiators, molecular weight regulators, and the like can be used.

  Examples of the other unsaturated monomers include aromatic vinyl monomers such as styrene, α-methylstyrene, and dimethylstyrene; ethylenically unsaturated carboxylic acids such as (meth) acrylamide, N, N-dimethylacrylamide, and N-methylolacrylamide. An acid amide monomer; an ethylenically unsaturated carboxylic acid alkyl ester monomer such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate; and Examples include vinyl acetate.

  Examples of the emulsifier include anionic surfactants such as dodecylbenzene sulfonate and aliphatic sulfonate; cationic surfactants such as polyethylene glycol alkyl ether and polyethylene glycol alkyl ester; and amphoteric surfactants. An anionic surfactant is preferably used.

  The polymerization initiator is not particularly limited as long as it is a radical initiator, but inorganic peroxides such as ammonium persulfate and potassium perphosphate; t-butyl peroxide, cumene hydroperoxide, p-menthane hydroperoxide, di- Organic peroxides such as t-butyl peroxide, t-butyl cumyl peroxide, dibenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, t-butyl peroxyisobutyrate; azobisisobuty Examples thereof include azo compounds such as rhonitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and methyl azobisisobutyrate.

  Examples of the molecular weight modifier include mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride, methylene chloride and methylene bromide. Among these, mercaptans are preferable. Furthermore, a dispersing agent, a pH adjuster, etc. can be used as needed.

In the present invention, the carboxylated acrylonitrile butadiene elastomer is widely a carboxyl obtained by copolymerizing acrylonitrile and butadiene constituting the main chain of rubber, at least one unsaturated carboxylic acid, and optionally other copolymerizable monomers. Includes elastomers containing groups. In addition, a part of the carboxyl group is a structure that is derivatized (for example, ester, amide, etc.) and a cross-link is formed between these constituent components. The method of improving the strength, flexibility and workability which are the characteristics of this structure can be solved by studying how to crosslink.
It is important to select a cross-linking agent. It is as follows when the kind of crosslinking agent to be used and which part is subjected to crosslinking are determined.

The carboxylated acrylonitrile butadiene elastomer of the present invention employs one containing 20 to 40% by weight of acrylonitrile and 4 to 8% by weight of unsaturated carboxylic acid, and is newly covalently bonded with a dihydrazide compound between the carboxyl groups of the acrylonitrile butadiene elastomer. By forming a cross-link selected from the cross-linking by ionic bond by metal ion or the cross-linking by covalent bond by dihydrazide compound, the conventional metal ion is not used at all, or the amount of metal ion used is conventionally A glove manufactured by a dip method using an elastomer molded body that can be reduced in comparison with the dihydrazide compound and formed into a crosslink that is difficult to be decomposed by water. Wear gloves To make it difficult to tear (strong breaking strength), to reduce the resistance applied to the finger when moving the finger, to satisfy that the hand does not get tired even if worn for a long time (soft and easy to stretch), etc. It has a characteristic that it has a strong resistance to permeation of chemicals and does not easily become brittle even when it comes into contact (chemical resistance).
Conventionally, zinc ions are often used as metal ions. When using zinc ions, the flexibility of the glove cannot be fully demonstrated, the binding by zinc ions is accelerated by sweat and moisture, and the strength of the glove is reduced. Since the result is that the object remains in a small amount, it was examined how to use zinc, and it was studied to reduce the amount of zinc used as much as possible. Specifically, by using a dihydrazide compound as a new carboxyl group cross-linking agent instead of zinc, a covalent bond is formed, and the use of zinc ion and dihydrazide compound can reduce the amount of zinc ion used to zero. Or the amount of zinc ions used can be reduced.

When the carboxylated acrylonitrile butadiene elastomer contains 20 to 40% by weight of acrylonitrile and 4 to 8% by weight of unsaturated carboxylic acid, the elastomer to be crosslinked is classified into the following two types according to Mooney viscosity. .
(1) A carboxylated acrylonitrile butadiene elastomer containing 20 to 40% by weight of acrylonitrile and 4 to 8% by weight of unsaturated carboxylic acid and having a Mooney viscosity (ML _{(1 + 4)} (100 ° C.)) of 100 to 220. This is the case when the molecular weight is large.
(2) A carboxylated acrylonitrile butadiene elastomer containing 20 to 40% by weight of acrylonitrile and 4 to 8% by weight of unsaturated carboxylic acid and having a Mooney viscosity (ML _{(1 + 4)} (100 ° C.)) of 40 to 100. In this case as well, although the molecular weight is smaller than in the case of (1), the molecular weight is high when viewed as a whole.

When cross-linking a carboxylated acrylonitrile butadiene elastomer containing 20 to 40% by weight of acrylonitrile and 4 to 8% by weight of unsaturated carboxylic acid and having a Mooney viscosity (ML _{(1 + 4)} (100 ° C.)) of 100 to 220 This is done as follows.

The resulting carboxylated acrylonitrile butadiene elastomer has a molecular weight such that the Mooney viscosity (ML (1 + 4) (100 ° C.)) is 100 to 220, preferably 100 to 190. If the Mooney viscosity is less than the lower limit, it is difficult to obtain sufficient strength. The upper limit is an actual measurement limit of Mooney viscosity, and if it exceeds this, the viscosity becomes high and molding processing becomes difficult.
The Mooney viscosity of the obtained elastomer was confirmed as follows.
A latex emulsion was dropped with a pipette while 200 ml of a saturated aqueous solution of a 4: 1 mixture of calcium oxide and calcium carbonate was stirred at room temperature to precipitate a solid rubber. The obtained solid rubber is taken out and stirred and washed with about 1000 ml of ion-exchanged water 10 times, and then the solid rubber is squeezed and dehydrated and vacuum dried (60 ° C., 72 hours) to prepare a rubber sample for measurement. did. The obtained rubber for measurement was passed through a 6-inch roll having a roll temperature of 50 ° C. and a roll gap of about 0.5 mm until the rubber was collected. JIS K6300-1: 2001 “Unvulcanized rubber—physical properties, Measurement was performed according to “How to Obtain Viscosity and Scorch Time Using a 1-Part Mooney Viscometer”.

The carboxylated acrylonitrile butadiene elastomer has a toluene weight swelling ratio of 180 to 220% by weight, preferably 190 to 210% by weight. If the swelling ratio is less than the lower limit, the degree of cross-linking is low, the strength when made into a glove is insufficient, and if it exceeds the upper limit, flexibility is insufficient.
The carboxylated acrylonitrile butadiene elastomer of (1) is further formed between the carboxyl groups by a crosslink by covalent bond with a dihydrazide compound or a crosslink by ionic bond with a metal ion and a crosslink by covalent bond with a dihydrazide compound. In thin gloves, in order to improve the deterioration of the durability of molded products due to sweat, moisture, etc., which is a drawback of metal crosslinking, metal ions that have been conventionally used for crosslinking between carboxyl groups are used. By manufacturing a glove by replacing part or all of the used ionic bond with a covalent bond using a dihydrazide compound, a glove that does not contain or reduce metal ions such as zinc ions can be obtained.
As the dihydrazide compound, a compound selected from adipic acid dihydrazide, sebacic acid dihydrazide, dodecanedihydrazide, isophthalic acid dihydrazide and aminopolyacrylamide is used. Two or more of these compounds may be used in combination.
The metal ion can be selected from zinc, magnesium, calcium, and aluminum. Usually, zinc ions are used. Two or more of these metal ions may be used in combination.

The carboxylated acrylonitrile butadiene elastomer can improve oil resistance and chemical resistance by increasing the content of the acrylonitrile component (elastomer A). However, the flexibility of the resulting glove is impaired and it becomes hard and difficult to stretch. In the present invention, an acrylonitrile butadiene elastomer (hereinafter also referred to as an elastomer B) acting as a softening agent coexists with an elastomer obtained by crosslinking the elastomer. As a result, the glove which is the product obtained can maintain flexibility.
In the present invention, non-sulfur crosslinking (preferably self-crosslinking) is performed, and further, a crosslinking is formed between carboxyl groups only by a covalent bond with a dihydrazide compound, or a crosslink by an ionic bond with a metal ion and a covalent bond with a dihydrazide compound. Are caused simultaneously. Apart from this, the elastomer B which is an acrylonitrile butadiene elastomer not containing a carboxyl group (specifically, the molecular weight is lower than that of the elastomer A and is calculated as an acetone-soluble component from the product) is used as the elastomer A. It can be made to act as a softening agent by mixing and using.
The elastomer B has 20 to 50% by weight, preferably 30 to 40% by weight, of acrylonitrile residues and the rest of butadiene residues. This is because if the amount of the acrylonitrile residue is less than the lower limit, the chemical resistance is deteriorated, and if the amount exceeds the upper limit, the molecular chain becomes rigid and the flexibility is impaired. Further, the weight average molecular weight in terms of styrene of the elastomer B is 7,000 to 50,000, preferably 9,000 to 30,000. Since the elastomer B does not contain a carboxyl group, a crosslinking reaction is not caused by a dihydrazide compound or metal ions. For this reason, elastomer B can be quantified as a soluble component when processing the glove which is a target product.
The amount ratio of the elastomer A and the elastomer B is 5 to 30% by weight of the elastomer B with respect to 95 to 70% by weight of the elastomer A (total 100% by weight).

Between the carboxyl groups of the mixture of Elastomer A and Elastomer B, a crosslink selected from a covalent bond by a dihydrazide compound, or a crosslink by an ionic bond by a metal ion and a crosslink by a covalent bond by a dihydrazide compound is formed.
In this case, it is not necessary to use sulfur and a vulcanization accelerator. As a result, the cross-linking agent used does not contain metal ions such as zinc ions, or the content of metal ions is reduced, so that it easily breaks when wet with sweat, moisture, etc. in the usage environment. Suitable for practical use, such as prevention of adverse effects caused by other metal ions, for example, prevention of contamination of products handled by workers with free metal ions, prevention of metal allergy It is possible to obtain an elastomer glove that is an elastomer molded product that has high breaking strength, flexibility, and chemical resistance, and is less likely to cause type IV allergy.

When cross-linking a carboxylated acrylonitrile butadiene elastomer containing 20 to 40% by weight of acrylonitrile and 4 to 8% by weight of unsaturated carboxylic acid and having a Mooney viscosity (ML _{(1 + 4)} (100 ° C.)) of 40 to 100 This is done as follows.

In this case as well, although the molecular weight is smaller than in the case of (1), the molecular weight is high when viewed as a whole.
Crosslinks selected from covalent crosslinks with dihydrazide compounds or ionic bonds with metal ions and crosslinks with covalent bonds with dihydrazide compounds are formed between carboxyl groups of carboxylated acrylonitrile butadiene elastomers, and sulfur or vulcanized between butadienes Crosslinking with sulfur is performed using an accelerator.
As a result, the cross-linking agent used does not contain metal ions such as zinc ions, or the content of metal ions is reduced, so that it easily breaks when wet with sweat, moisture, etc. in the usage environment. This can prevent other adverse effects caused by other metal ions, for example, contamination of the product handled by the operator with free metal ions.

  When a carboxylated acrylonitrile butadiene elastomer containing 20 to 40% by weight of acrylonitrile having a specific Mooney viscosity and 4 to 8% by weight of an unsaturated carboxylic acid is crosslinked, the elastomer composition having a high molecular weight is Although satisfying the required properties, the flexibility is poor, and the glove which is an elastomer molded product becomes difficult to use. As described in the background art, although there is an invention for improving flexibility in rubber gloves, an additive is added to obtain flexibility, and means for crosslinking, means for improving flexibility, etc. A glove, which is an elastomer molded product that has been adopted to give flexibility to the elastomer molded product, has been solved as follows.

The cross-linked structure employed in the present invention is a non-sulfur cross-linked structure, whereby the content of elemental sulfur detected by the neutralization titration method of the carboxylated acrylonitrile butadiene elastomer combustion gas absorbent is the carboxylated acrylonitrile. It is 1.0 weight% or less of a butadiene elastomer weight. The quantification method comprises absorbing 0.01 g of a carboxylated acrylonitrile butadiene elastomer sample in air at 1350 ° C. for 10 to 12 minutes and absorbing it in H ₂ O ₂ water to which a mixed indicator is added. This is a method of neutralization titration with a 01N NaOH aqueous solution.

  The non-sulfur cross-linked structure is not particularly limited, for example, cross-linking between main chains by organic peroxides, oximes, etc., cross-linking between carboxyl groups such as acid anhydrides, cross-linking agents such as polyepoxides, polyols, polyimides, mono And crosslinking between carboxyl groups using polycarbodiimide, polyisocyanate, etc., introducing a structural unit having a carboxyl group and a reactive group such as a glycidyl group into the main chain, and crosslinking by reaction between the group and the carboxyl group, etc. Is mentioned. Preferably, self-crosslinking, i.e., crosslinking that is stable under normal storage conditions, but formed, for example, by evaporating or heating water, or by changing pH, without the addition of a separate cross-linking agent. It is preferable. Examples of such crosslinking include those by carboxyl group auto-oxidation, those in which n-methylolacrylamide units are introduced and self-condensed, and the Michael reaction of acetoacetoxy groups and unsaturated bonds.

  Next, the obtained elastomer is subjected to a non-sulfur crosslinking step by heating or evaporating water. However, this step may be performed simultaneously with crosslinking with divalent metal ions described later or in a heating step after the ion crosslinking.

For the resulting carboxylated acrylonitrile butadiene elastomer comprising 20 to 40% by weight of acrylonitrile and 4 to 8% by weight of unsaturated carboxylic acid and having a Mooney viscosity (ML (1 + 4) (100 ° C.)) of 40 to 100 When cross-linking is performed as follows.
The Mooney viscosity of the elastomer was confirmed as follows.
A latex emulsion was dropped with a pipette while 200 ml of a saturated aqueous solution of a 4: 1 mixture of calcium oxide and calcium carbonate was stirred at room temperature to precipitate a solid rubber. The obtained solid rubber is taken out and stirred and washed with about 1000 ml of ion-exchanged water 10 times, and then the solid rubber is squeezed and dehydrated and vacuum dried (60 ° C., 72 hours) to prepare a rubber sample for measurement. did. The obtained rubber for measurement was passed through a 6-inch roll having a roll temperature of 50 ° C. and a roll gap of about 0.5 mm until the rubber was collected. JIS K6300-1: 2001 “Unvulcanized rubber—physical properties, Measurement was performed according to “How to Obtain Viscosity and Scorch Time Using a 1-Part Mooney Viscometer”.

The carboxylated acrylonitrile butadiene elastomer has a toluene weight swelling ratio of 180 to 220% by weight, preferably 190 to 210% by weight. If the swelling ratio is less than the lower limit, the degree of cross-linking is low, the strength when made into a glove is insufficient, and if it exceeds the upper limit, flexibility is insufficient.
The carboxylated acrylonitrile butadiene elastomer is further formed between the carboxyl groups by a crosslink by a covalent bond with a dihydrazide compound or a crosslink by an ionic bond with a metal ion and a crosslink by a covalent bond with a dihydrazide compound. Cross-linking between butadienes is performed with sulfur.
Thin gloves use metal ions that have been used for crosslinking between carboxyl groups in order to improve the deterioration of the durability of molded products due to sweat, moisture, etc., which is a drawback of metal crosslinking. By manufacturing a glove by replacing a part or all of the existing ionic bond with a covalent bond using a dihydrazide compound, a glove that does not contain or reduce metal ions such as zinc ions can be obtained.
As the dihydrazide compound, a compound selected from adipic acid dihydrazide, sebacic acid dihydrazide, dodecanedihydrazide, isophthalic acid dihydrazide and aminopolyacrylamide is used. Two or more of these compounds may be used in combination.
The metal ion can be selected from zinc, magnesium, calcium, and aluminum. Usually, zinc ions are used. Two or more of these metal ions may be used in combination.

The carboxylated acrylonitrile butadiene elastomer can improve oil resistance and chemical resistance by increasing the content of the acrylonitrile component (elastomer A). However, the flexibility of the resulting glove is impaired and it becomes hard and difficult to stretch. In the present invention, an acrylonitrile butadiene elastomer (hereinafter also referred to as an elastomer B) acting as a softening agent coexists with an elastomer obtained by crosslinking the elastomer. As a result, the glove which is the product obtained can maintain flexibility.
In the present invention, non-sulfur crosslinking (preferably self-crosslinking) is performed, and further, a crosslinking is formed between carboxyl groups only by a covalent bond with a dihydrazide compound, or a crosslink by an ionic bond with a metal ion and a covalent bond with a dihydrazide compound. Are caused simultaneously. Apart from this, the elastomer B which is an acrylonitrile butadiene elastomer not containing a carboxyl group (specifically, the molecular weight is lower than that of the elastomer A and is calculated as an acetone-soluble component from the product) is used as the elastomer A. It can be made to act as a softening agent by mixing and using.
The elastomer B has 20 to 50% by weight, preferably 30 to 40% by weight, of acrylonitrile residues and the rest of butadiene residues. This is because if the amount of the acrylonitrile residue is less than the lower limit, the chemical resistance is deteriorated, and if the amount exceeds the upper limit, the molecular chain becomes rigid and the flexibility is impaired. Further, the weight average molecular weight in terms of styrene of the elastomer B is 7,000 to 50,000, preferably 9,000 to 30,000. Since the elastomer B does not contain a carboxyl group, a crosslinking reaction is not caused by a dihydrazide compound or metal ions. For this reason, elastomer B can be quantified as a soluble component when processing the glove which is a target product.
The amount ratio of the elastomer A and the elastomer B is 5 to 30% by weight of the elastomer B with respect to 95 to 70% by weight of the elastomer A (total 100% by weight).

Between the carboxyl groups of the mixture of Elastomer A and Elastomer B, a crosslink selected from a covalent bond by a dihydrazide compound, or a crosslink by an ionic bond by a metal ion and a crosslink by a covalent bond by a dihydrazide compound is formed.

Next, an operation for manufacturing a glove will be described.
The thin glove obtained by crosslinking between carboxyl groups of the carboxylated acrylonitrile butadiene elastomer of (1) as described above does not contain metal ions such as zinc ions by introducing a covalent bond with a dihydrazide compound. Or, since it is a reduced glove, it can be prevented from being decomposed by sweat or moisture under the use environment of the glove, which is a drawback of metal cross-linking, and can have durability.

The procedure for crosslinking the mixture of elastomer A and elastomer B to obtain an elastomer molded product, particularly a thin glove, is as follows.
First, an emulsion composition containing elastomer A and elastomer B is prepared. The usual composition is that the solid content of both elastomer A and elastomer B is 100 phr, a pH adjuster (necessary amount for adjusting the pH to 9 to 10), a dihydrazide compound, or a metal oxide and a dihydrazide compound as a crosslinking agent ( 0.5-8.0 phr), titanium oxide (0.2-3.0 phr), dispersant (0.5-2.0 phr), antioxidant (0.1-1.5 phr), colorant (as appropriate ), Water (amount for adjusting the solid content to 18 to 30% by weight).
As the dispersant, an anionic surfactant can be used. Specifically, sodium salt of naphthalene sulfonic acid polycondensate, Tamol NN9104, can be used.
As the antioxidant, anti-wrinkle type Wingstay L made of a polymeric hindered phenol can be used.
The composition of the emulsion composition in which the former is immersed is as shown in Table 1 below. The former is immersed in this emulsion composition, and the emulsion composition is adhered to the surface of the hand shape by dipping, molded into the shape of a glove, and heated to complete crosslinking, thereby obtaining an elastomer molded product.

(2) When using a carboxylated acrylonitrile butadiene elastomer containing 20 to 40% by weight of acrylonitrile and 4 to 8% by weight of unsaturated carboxylic acid and having a Mooney viscosity (ML _{(1 + 4)} (100 ° C.)) of 40 to 100 explain.

The elastomer (2) has a lower Mooney viscosity than the elastomer (1). The production method is the same as (1), but non-sulfur crosslinking may not be performed as a means for increasing Mooney viscosity. By adjusting various conditions, an elastomer having the desired Mooney viscosity is obtained.

Crosslinking for obtaining an elastomer molded product is performed as follows.
Between the carboxyl groups of the carboxylated acrylonitrile butadiene elastomer, a crosslink selected from a covalent bond with a dihydrazide compound or a crosslink with an ionic bond with a metal ion and a crosslink with a covalent bond with a dihydrazide compound is formed.
The dihydrazide compound is selected from adipic acid dihydrazide, sebacic acid dihydrazide, dodecanedihydrazide, isophthalic acid dihydrazide and aminopolyacrylamide. Two or more of these compounds may be used in combination.
The metal ion can be selected from zinc, magnesium, calcium, and aluminum. Usually, zinc ions are used. Two or more of these metal ions may be used in combination.
In the case of the elastomer (2), since the Mooney viscosity is low and sufficient strength cannot be obtained only by crosslinking between carboxyl groups, crosslinking between sulfur and butadiene is also formed.

In the present invention, the elastomer obtained by crosslinking the elastomer is crosslinked in the state in which an elastomer that acts as a softening agent (same as the above-mentioned elastomer B) coexists. As a result, the glove which is the product obtained can maintain flexibility.
Elastomer B can be quantified as a soluble component when processing the target product, a glove.
The amount ratio of the two types of elastomer is 5 to 30% by weight of the elastomer B with respect to the elastomer A of 95 to 70% by weight (total of 100% by weight).

A method of obtaining an elastomer molded product by crosslinking the elastomer A and the elastomer B is as follows. The composition for performing crosslinking is as follows.
First, an emulsion composition containing elastomer A and elastomer B is prepared. The composition of the emulsion composition is such that a pH adjuster (amount for adjusting the pH to 9 to 10), a sulfur vulcanizing agent and a dihydrazide compound, or a metal oxide with respect to 100 phr solids of the elastomer A and the elastomer B, Dihydrazide compound and sulfur vulcanizing agent and dihydrazide compound (0.5 to 8.0 phr), titanium oxide (0.2 to 3.0 phr), dispersant (0.5 to 2.0 phr), antioxidant (0 0.1 to 1.5 phr), a colorant (as appropriate), and water (an amount for adjusting the solid content to 18 to 30% by weight). Next, the handprint of the glove is dipped with the emulsion composition, the emulsion composition is attached to the surface of the handprint by the dipping method, molded into the shape of the glove, and heated to complete the crosslinking, thereby obtaining an elastomer molded product. it can.
Metal oxides, sulfur-based vulcanizing agents and dihydrazide compounds are all crosslinking agents. The amount of these crosslinking agents used means that the total amount of crosslinking agents is 0.5 to 8.0 phr.
A sulfur-based vulcanizing agent is a mixture of sulfur and a vulcanization accelerator. Examples of the vulcanization accelerator include dithiocarbamate, tetramethylthiuram disulfide (TMTD), and mercaptobenzothiazole (MBT). The weight ratio of sulfur to vulcanization accelerator is 1: 0.1 to 0.2.
As the dispersant, an anionic surfactant can be used. Specifically, sodium salt of naphthalene sulfonic acid polycondensate, Tamol NN9104, can be used.
As the antioxidant, anti-wrinkle type Wingstay L made of a polymeric hindered phenol can be used.

The dihydrazide compound used is selected from adipic acid dihydrazide, sebacic acid dihydrazide, dodecanedihydrazide, isophthalic acid dihydrazide and aminopolyacrylamide. It is a carboxylated acrylonitrile butadiene elastomer obtained by crosslinking using these.

The composition of the emulsion composition is indicated as follows.

The procedure for manufacturing gloves using the former is as follows. This procedure is the same when the elastomer (1) is used and when the elastomer (2) is used.
(A) The former is washed with a cleaning solution to remove dirt, washed with cold water, and dried. The dried former is carried out by either a direct dipping method or a flocculant dipping method. These usages are determined according to the product. The direct dipping method involves dipping directly into the dry mold or former of the product in the emulsion composition prepared by the formulation of the present invention.
(B) A step of immersing the mold or former in a coagulant solution containing 8 to 17% by weight of Ca ²⁺ ions for 15 seconds. The coagulant is an aqueous solution in which calcium nitrate is added to water and Ca ²⁺ ions are 10% by weight of calcium. Has been adjusted as. The mold or former is immersed in this. As a result, a coagulant is attached to the surface of the former. The time is 10 to 20 seconds. Wetting agents and anti-sticking agents can also be added. Specifically, zinc stearate and calcium stearate.
(C) A step of drying the former to which the coagulant is adhered at 60 ° C. and partially or partially drying the former (d) A former obtained by adhering and drying the coagulant obtained in the step (c) Immerse the former with the coagulant attached in the composition for producing the elastomer of 1 to 20 seconds under the temperature condition of 30 ° C. by immersing the former with the coagulant attached in the emulsion composition under the temperature condition of 30 ° C. for 15 seconds. The emulsion composition is deposited. The soaking process is usually performed several times.
(E) The former obtained in the step (d) is treated with water to separate the drug (leaching). The former coated with the partially dried latex is heated in hot water (30 to 70 ° C.). For 90 to 140 seconds.
(F) Step of beading (sleeve winding) the former obtained in the step (e) After the leaching step is completed, beading (sleeve winding) is performed.
(G) Process of drying the mold or former obtained in the step (f) in the furnace The glove former is dried at 80 to 120 ° C. for 250 to 300 seconds.
(H) Step of crosslinking the former obtained in the step (g) The glove former coated with the dried latex is crosslinked at 120 to 150 ° C. for 20 to 30 minutes.
(I) The step of drying after the surface of the crosslinked elastomer film obtained in the step (h) is subjected to post-leaching (washing with water to remove contained chemicals) and post-leaching is performed at 30 to 80 ° C. 60 to 80 seconds. Do this in two steps.
(J) The surface of the glove is chlorinated.
The glove which consists of a thin film of an elastomer can be manufactured through a series of processes above.

Measurement of the properties and performance of the gloves Measure the properties of the manufactured gloves by performing the measurement operation on the following items.
(A) Amount of acrylonitrile The amount of acrylonitrile based on the target elastomer is calculated from the measurement results of the amount of N element and the amount of ash in the elastomer from the following formula.
Elastomer-based N amount (%) = N element amount% / 100-ash content%
N (wt%) on the basis of elastomer = 0.2643 (% acrylonitrile content in elastomer) −0.0072
N element analysis amount is measured by CE INSTRUMENT CHN element analyzer,
The amount of ash was measured using a thermobalance TGA-50H manufactured by Shimadzu Corporation, and the residue in air at 800 ° C. was used as the ash.
(B) Acetone-soluble component The amount of acetone-soluble component was determined by accurately weighing 1 g of an elastomer sample and immersing it in a boiled acetone solvent for 24 hours, collecting the acetone solution, concentrating and drying the residue. It can measure as an extract and can measure the content of unmodified NBR rubber which is not carboxylated as an acetone-soluble component from the FT-IR analysis result.
By analyzing the acetone-soluble component by gel permeation chromatography (GPC), the weight molecular weight distribution (in terms of monodisperse polystyrene) can be measured. From the measurement results, the molecular weight distribution was in the range of 7,000 to 50,000.
GPC measurement conditions are as follows.
Equipment: LC-10A manufactured by Shimadzu Corporation Detector: RI (refractive index detector)
Column: SHODEX KF-800P + KF805L + KF-801 (molecular weight range: 100 to 5.6 × 10 ⁶ )
Tetrahydrofuran (THF) was used as the eluent.
(C) Toluene weight swelling ratio The toluene weight swelling ratio is measured as a measure for measuring the crosslinking density of the elastomer. It measures about the weight increase amount of the rubber glove 72 hours after toluene immersion.
Toluene weight swelling ratio = (swelling weight of rubber gloves / initial weight of rubber gloves) × 100 (%) was calculated.
(D) Elemental analysis of the entire glove (CHN elemental analyzer / ICP emission spectroscopic analysis)
The carbon (C), hydrogen (H), and nitrogen (N) contents of the elastomer were calculated using a CHN element analyzer. Sulfur (S) was quantified by ICP emission spectroscopic analysis by adding an Eschaka mixture to the elastomer, followed by heat treatment, extracting with warm water.
(E) Measurement of tensile strength (MPa), elongation at break (%), 500% elastic modulus (MPa) Tensile strength (MPa), elongation at break (%), and 500% elastic modulus (MPa), manufactured by A & D TENSILON universal tensile tester, RTC-1310A, dumbbell No. 5 test piece, test speed 500 mm / min, chuck interval 75 mm, mark interval 25 mm.
(f) Durability test (Durability)
The durability test was performed by the following operation.
After the tensile test piece is immersed in artificial sweat for 24 hours at room temperature, 100% stretching is repeated and the time until the test piece breaks is measured.

The contents of the present invention will be described in detail below with reference to examples.
The present invention is not limited to this embodiment.

94% by weight of elastomer A (5% by weight of methacrylic acid, carboxylated acrylonitrile butadiene elastomer with Mooney viscosity adjusted to 25% by weight of acrylonitrile) and 6% by weight of elastomer B (25% by weight of acrylonitrile, 75% by weight of butadiene) An emulsion composition comprising a mixture of nitrile butadiene elastomer) was prepared.
The manufacturing method of the elastomer B is as follows.
In a pressure-resistant polymerization reactor equipped with a stirrer, 120 parts of ion exchange water, 35 parts by weight of acrylonitrile, 65 parts by weight of 1,3-butadiene, 3 parts by weight of sodium dodecylbenzenesulfonate, 0.3 part by weight of potassium sulfate, and ethylenediamine After reacting an emulsion comprising 0.05 parts by weight of sodium tetraacetate and 1.0 parts by weight of t-dodecyl mercaptan at 60 to 80 ° C. for 5 hours, a reaction terminator was added to complete the polymerization, After removing unreacted monomers from the obtained latex, the pH and concentration of the copolymer latex were adjusted to obtain an elastomer B having a solid content concentration of 45% and a weight average molecular weight of 19700 in terms of polystyrene.
The solid content of the emulsion composition is 25% by weight. The composition of the emulsion composition is as shown in Table 3 (sulfur vulcanizing agent, zinc oxide and adipic acid dihydrazide 1.5, 0.5, 3.0 phr as the crosslinking agent). The former was dipped in the emulsion composition, the emulsion composition was attached to the surface of the former, dried and crosslinked, and a glove composed of a thin film was produced.

Table 4 shows the results of the calculation of the acrylonitrile amount, the acetone-soluble component amount, the toluene weight swelling ratio, the component analysis, the tensile properties, and the durability test of Example 1.
In the durability test of Example 1, it was confirmed that the durability was maintained without being broken up to 70 times.

Comparative Example 1
In Comparative Example 1, a glove made of a thin film was produced in the same manner as in Example 1 except that adipic acid dihydrazide shown in Table 3 was not used and only zinc oxide and a sulfur-based vulcanizing agent were crosslinked.
Table 4 shows the results of calculation of the amount of acrylonitrile, amount of acetone-soluble component, toluene weight swelling rate, component analysis, tensile properties, and durability test of Comparative Example 1.
As shown in Table 5, the durability evaluation result was broken in 25 times in Comparative Example 1.

95% by weight of elastomer A (5% by weight of methacrylic acid, carboxylated acrylonitrile butadiene elastomer with Mooney viscosity of 150 adjusted to 28% by weight of acrylonitrile) and 5% by weight of elastomer B (25% by weight of acrylonitrile, 75% by weight of acrylonitrile) An emulsion composition was prepared according to Table 3 using a mixture of (tolyl butadiene elastomer). However, the sulfur vulcanizing agent was removed from the composition of the crosslinking agent. A glove made of a thin film was produced by the same dipping method as in Example 1.
Table 4 shows the results of calculation of the amount of acrylonitrile, amount of acetone-soluble component, toluene weight swelling rate, component analysis, tensile properties, and durability test of Example 2.
The durability evaluation result showed a result that could not be broken up to 80 times. The durability was fully maintained.

Comparative Example 2
A glove made of a thin film of elastomer was produced in the same manner as in Example 2, except that the sulfur-based vulcanizing agent and adipic acid dihydrazide shown in Table 3 were not used, but only zinc oxide was used for vulcanization. did.
Table 4 shows the results of calculation of the amount of acrylonitrile, amount of acetone-soluble component, toluene weight swelling ratio, component analysis, tensile properties, and durability test of Comparative Example 2.
The durability evaluation result was broken in 20 times in Comparative Example 2.

82% by weight of elastomer A (5% by weight of methacrylic acid, carboxylated acrylonitrile butadiene having Mooney viscosity of 120 adjusted to 33% by weight of acrylonitrile) and 18% by weight of elastomer B (33% by weight of acrylonitrile, 67% by weight of acrylonitrile) An emulsion composition was prepared according to Table 3 using a mixture of (tolylbutadiene). However, the only cross-linking agent was adipic acid dihydrazide. A glove made of a thin film was produced by the same dipping method as in Example 1.
Table 4 shows the results of calculation of acrylonitrile amount, acetone-soluble component amount, toluene weight swelling ratio, component analysis, tensile properties, and durability test of Example 3.
The result of durability evaluation showed a result that could not be broken up to 120 times. The durability was fully maintained.

Comparative Example 3
A glove composed of a thin film of elastomer 2mer was produced in the same manner as in Example 3 except that the crosslinking agent was only zinc oxide.
Table 4 shows the results of calculation of the amount of acrylonitrile, amount of acetone-soluble component, toluene weight swelling rate, component analysis, tensile properties, and durability test of Comparative Example 3.
In Comparative Example 3, it was broken after 35 times.

The results of Examples 1 to 3 and the results of Comparative Examples are shown below.

The cross-linking method shown in the present invention can be employed in a method for producing a glove or the like that does not contain zinc oxide or has a reduced content of zinc oxide.

Claims (10)

Between carboxyl groups of a carboxylated acrylonitrile butadiene elastomer containing 20 to 40% by weight of acrylonitrile and 4 to 8% by weight of unsaturated carboxylic acid, by covalent bonding with a dihydrazide compound or by ionic bonding with a metal ion and by a dihydrazide compound An elastomer molded product in which a cross-link selected from cross-linking by a covalent bond is formed. A carboxylated acrylonitrile butadiene elastomer comprising 20 to 40% by weight of acrylonitrile and 4 to 8% by weight of unsaturated carboxylic acid, and having a Mooney viscosity (ML _{(1 + 4)} (100 ° C)) of 100 to 220 The crosslink selected from the crosslink by a covalent bond by a dihydrazide compound or a crosslink by an ionic bond by a metal ion and a crosslink by a covalent bond by a dihydrazide compound is formed between certain carboxyl groups. Elastomer molding. A carboxylated acrylonitrile butadiene elastomer comprising 20 to 40% by weight of acrylonitrile and 4 to 8% by weight of unsaturated carboxylic acid, and having a Mooney viscosity (ML _{(1 + 4)} (100 ° C.)) of 40 to 100 A sulfur bridge is formed between certain butadienes, and a bridge selected from a covalent bond by a dihydrazide compound or a crosslink by an ionic bond by a metal ion and a crosslink by a covalent bond by a dihydrazide compound is also formed between carboxyl groups. The elastomer molded product according to claim 1, wherein It comprises 95 to 70% by weight of the carboxylated acrylonitrile butadiene elastomer according to claim 2, 20 to 50% by weight of acrylonitrile and 50 to 80% by weight (100% by weight in total) of butadiene, and has a weight average molecular weight (polystyrene conversion value) of 7, Crosslink by covalent bond with dihydrazide compound or ionic bond with metal ion and dihydrazide compound between carboxyl groups of elastomer mixture consisting of 5 to 30% by weight (total 100% by weight) of acrylonitrile butadiene elastomer of 000 to 50,000 An elastomer molded product characterized in that a cross-link selected from cross-linking by a covalent bond is formed. It consists of 95 to 70% by weight of the carboxylated acrylonitrile butadiene elastomer according to claim 3, 20 to 50% by weight of acrylonitrile and 50 to 80% by weight (100% by weight in total) of butadiene, and has a weight average molecular weight (polystyrene equivalent value) of 7, Sulfur bridges are formed between the butadienes of the elastomer mixture composed of 5 to 30% by weight (100% by weight in total) of acrylonitrile butadiene elastomer of 000 to 50,000, and crosslinks by covalent bonds with dihydrazide compounds between the carboxyl groups. Or an elastomer molded product, wherein a crosslink selected from a crosslink by ionic bond with a metal ion and a crosslink by covalent bond with a dihydrazide compound is formed. 6. The elastomer molded product according to claim 1, wherein the dihydrazide compound is a dihydrazide selected from adipic acid dihydrazide, sebacic acid dihydrazide, dodecanedihydrazide, isophthalic acid dihydrazide, and aminopolyacrylamide. The elastomer molded article according to any one of claims 1 to 5, wherein the metal ion is a metal ion selected from ions of zinc, magnesium, calcium, or aluminum metal. An emulsion composition for dipping a former comprising the elastomer mixture according to claim 4 or 5. 9. A former is immersed in the emulsion composition according to claim 8, the former with the emulsion composition attached to the surface is pulled up and dried, and then heated to crosslink the elastomer to form a glove on the surface of the former. A glove characterized by being obtained by separating from a former. The glove according to claim 9, wherein the zinc content is 0.4% by weight or less.