Chlorobutadiene polymers, methods for producing the same, chlorobutadiene polymer compositions, and dip-molded articles

Abstract

A chloroprene polymer containing at least one selected from the group consisting of a homopolymer of chloroprene and a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene, having a first peak with a weight average molecular weight of 500,000 to 900,000 and a second peak with a weight average molecular weight of 7,000 to 80,000 in a gel permeation chromatography measurement of a toluene-soluble component, and a toluene-insoluble component of 60% by mass or more.

Description

Technical Field

[0001] This invention relates to chloroprene polymers and their manufacturing methods, chloroprene polymer compositions, and impregnation molded articles. Background Technology

[0002] Chloroprene polymers have been used in various fields, including impregnated molded bodies (impregnated products), fiber treatment agents, paper processing agents, adhesives, bonding agents, elastic bitumen (modified bitumen), and elastic cement. In particular, chloroprene polymers are used as a main raw material in various gloves for household, industrial, and surgical applications. Previously, natural rubber was mainly used in glove applications, but allergies caused by proteins in natural rubber have become a problem, leading to a growing recommendation for synthetic rubber gloves. Chloroprene polymers possess physical properties similar to natural rubber in terms of feel and other aspects, and therefore, they are being researched as a substitute material for natural rubber (see, for example, Patent Documents 1-2 below).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2019 / 009038

[0006] Patent Document 2: Japanese Patent Application Publication No. 2019-143002 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In impregnated molded articles (gloves, etc.) obtained using chloroprene polymers, the flexibility is sometimes inferior compared to that obtained using natural rubber or isoprene rubber. Therefore, for chloroprene polymers, there is a need to improve the flexibility of impregnated molded articles obtained using chloroprene polymers.

[0009] In addition, for chloroprene polymers, it is required that the impregnated molded articles obtained using chloroprene polymers achieve not only excellent flexibility but also excellent tensile strength.

[0010] One aspect of the present invention aims to provide a chloroprene polymer that yields an impregnated molded article with excellent flexibility and tensile strength. Another aspect of the present invention aims to provide a chloroprene polymer composition containing the above-described chloroprene polymer. Another aspect of the present invention aims to provide an impregnated molded article of the above-described chloroprene polymer composition. Another aspect of the present invention aims to provide a method for manufacturing a chloroprene polymer that yields an impregnated molded article with excellent flexibility and tensile strength.

[0011] Methods for solving problems

[0012] One aspect of the present invention relates to a chloroprene polymer comprising at least one selected from the group consisting of a homopolymer of chloroprene and a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene, having, in a gel permeation chromatography determination of the toluene-soluble component, a first peak having a weight-average molecular weight of 500,000 to 900,000 and a second peak having a weight-average molecular weight of 7,000 to 80,000, and having a toluene-insoluble component of 60% by mass or more.

[0013] The aforementioned chloroprene polymer can be a mixture of polymer A and polymer B, wherein polymer A contains a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene, and polymer B contains at least one selected from the group consisting of homopolymers of chloroprene and copolymers of chloroprene and 2,3-dichloro-1,3-butadiene. The weight average molecular weight of the toluene-soluble component in polymer A is 500,000 to 900,000, the weight average molecular weight of the toluene-soluble component in polymer B is 7,000 to 80,000, the toluene-insoluble component in polymer A is 70% by mass or more, and the toluene-insoluble component in polymer B is 5% by mass or less.

[0014] Another aspect of the present invention relates to a chloroprene polymer composition comprising the above-described chloroprene polymer.

[0015] Another aspect of the present invention relates to an impregnated molded article of the above-described chloroprene polymer composition.

[0016] Another aspect of the present invention relates to a method for manufacturing a chloroprene polymer, comprising a step of mixing polymer A and polymer B, wherein polymer A is obtained by polymerizing chloroprene and 2,3-dichloro-1,3-butadiene in the presence of a chain transfer agent, pure water, alkali, emulsifier, reducing agent, and polymerization initiator at a polymerization temperature of 10–45°C and a polymerization rate of 80–95%, and polymer B is obtained by polymerizing 90–100 parts by mass of chloroprene in the presence of 1–10 parts by mass of a chain transfer agent, pure water, emulsifier, alkali, reducing agent, and polymerization initiator at a polymerization temperature of 10–45°C and a polymerization rate of 60–90%, wherein the proportion of 2,3-dichloro-1,3-butadiene in the aforementioned polymerization of polymer B is 10 parts by mass or less.

[0017] Invention Effects

[0018] According to one aspect of the present invention, a chloroprene polymer capable of producing an impregnated molded article with excellent flexibility and tensile strength can be provided. According to another aspect of the present invention, a chloroprene polymer composition containing the above-described chloroprene polymer can be provided. According to another aspect of the present invention, an impregnated molded article of the above-described chloroprene polymer composition can be provided. According to another aspect of the present invention, a method for manufacturing a chloroprene polymer capable of producing an impregnated molded article with excellent flexibility and tensile strength can be provided. Detailed Implementation

[0019] The embodiments of the present invention will now be described in detail. It should be noted that the present invention is not limited to the embodiments described below.

[0020] In this specification, "above A" in a numerical range refers to A and the range greater than A. "Below A" in a numerical range refers to A and the range less than A. In the numerical ranges described in stages in this specification, the upper or lower limit of a certain stage's numerical range can be arbitrarily combined with the upper or lower limits of other stages' numerical ranges. In the numerical ranges described in this specification, the upper or lower limit can be replaced with the values ​​shown in the examples. "A or B" can refer to either A or B, or both. Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more. Regarding the content of each component in the composition, in the case where multiple substances belonging to each component are present in the composition, unless otherwise specified, it refers to the total amount of the multiple substances present in the composition. "(Meth)acrylic acid" refers to at least one of acrylic acid and its corresponding methacrylic acid, and the same applies to "(meth)acrylate" and other similar expressions. In the determination of "toluene soluble components" and "toluene insoluble components", toluene at room temperature (23°C) can be used.

[0021] <Chloroprene polymers and chloroprene polymer compositions>

[0022] First, the chloroprene polymer according to this embodiment will be described. The chloroprene polymer according to this embodiment is a polymer having chloroprene (2-chloro-1,3-butadiene) as a monomer unit, and contains at least one selected from the group consisting of homopolymers of chloroprene and copolymers of chloroprene and 2,3-dichloro-1,3-butadiene. The chloroprene polymer according to this embodiment can be formed by dispersing a homopolymer of chloroprene or a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene in water.

[0023] Regarding the chloroprene polymer according to this embodiment, in the gel permeation chromatography (GPC) determination of the toluene-soluble components, it exhibits a first peak with a weight-average molecular weight (Mw) of 500,000 to 900,000 and a second peak with a weight-average molecular weight (Mw) of 7,000 to 80,000. The toluene-insoluble components of the chloroprene polymer according to this embodiment are 60% by mass or more.

[0024] According to the chloroprene polymer of this embodiment, an impregnated molded article with excellent flexibility and tensile strength can be obtained. According to the chloroprene polymer of this embodiment, an impregnated molded article with excellent flexibility, tensile strength, and elongation at break can also be obtained.

[0025] The first and second peaks mentioned above in the GPC determination of toluene-soluble components can be obtained by converting the weight-average molecular weight to polystyrene. The GPC determination can be performed under the conditions described in the examples.

[0026] Excellent softness can be obtained if the toluene-insoluble content of the chloroprene polymer is 60% or more by mass. The toluene-insoluble content of the chloroprene polymer can be 63% or more by mass, 65% or more by mass, 68% or more by mass, 70% or more by mass, 72% or more by mass, 75% or more by mass, 77% or more by mass, 78% or more by mass, 80% or more by mass, or 83% or more by mass. Alternatively, the toluene-insoluble content of the chloroprene polymer can be less than 85% by mass, less than 83% by mass, less than 80% by mass, less than 78% by mass, less than 77% by mass, less than 75% by mass, less than 72% by mass, less than 70% by mass, less than 68% by mass, less than 65% by mass, or less than 63% by mass. From these perspectives, the toluene-insoluble content of the chloroprene polymer can be 60–85% by mass, 60–83% by mass, 60–80% by mass, 60–75% by mass, 60–70% by mass, 65–83% by mass, 65–80% by mass, 65–75% by mass, 65–70% by mass, 70–83% by mass, 70–80% by mass, 70–75% by mass, 75–83% by mass, or 75–80% by mass.

[0027] The chloroprene polymer involved in this embodiment can be as follows: the chloroprene polymer is a mixture of polymer A and polymer B, wherein polymer A contains a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene, and polymer B contains at least one selected from the group consisting of a homopolymer of chloroprene and a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene; the weight average molecular weight (Mw) of the toluene-soluble component in polymer A is 500,000 to 900,000, the weight average molecular weight (Mw) of the toluene-soluble component in polymer B is 7,000 to 80,000, the toluene-insoluble component in polymer A is 70% by mass or more, and the toluene-insoluble component in polymer B is 5% by mass or less. In this embodiment, based on the total of polymer A and polymer B, the proportion of polymer A, in terms of solid components, can be 70% to 95% by mass (i.e., the mass ratio of the solid components of polymer A / polymer B can be 70 / 30 to 95 / 5).

[0028] The weight-average molecular weight of the toluene-soluble components in polymers A and B can be obtained by GPC determination and can be used as the weight-average molecular weight converted to polystyrene. GPC determination can be performed under the conditions described in the examples.

[0029] Excellent tensile strength can be obtained if the weight-average molecular weight of the first peak of the chloroprene polymer or the weight-average molecular weight of the toluene-soluble component in polymer A is 500,000 or higher. From the viewpoint of easily obtaining excellent tensile strength, the weight-average molecular weight of the first peak of the chloroprene polymer and the weight-average molecular weight of the toluene-soluble component in polymer A can be 530,000 or higher, 550,000 or higher, 580,000 or higher, 600,000 or higher, 630,000 or higher, 650,000 or higher, 680,000 or higher, 700,000 or higher, 730,000 or higher, 750,000 or higher, 780,000 or higher, 800,000 or higher, 830,000 or higher, or 850,000 or higher.

[0030] Excellent flexibility can be obtained if the weight average molecular weight of the first peak of the chloroprene polymer or the weight average molecular weight of the toluene-soluble component in polymer A is 900,000 or less. From the viewpoint of easily obtaining excellent flexibility, the weight average molecular weight of the first peak of the chloroprene polymer and the weight average molecular weight of the toluene-soluble component in polymer A can be 850,000 or less, 830,000 or less, 800,000 or less, 780,000 or less, 750,000 or less, 730,000 or less, 700,000 or less, 680,000 or less, 650,000 or less, 630,000 or less, 600,000 or less, 580,000 or less, 550,000 or less, or 530,000 or less.

[0031] From these perspectives, the weight-average molecular weight of the first peak of the chloroprene polymer and the weight-average molecular weight of the toluene-soluble component in polymer A can be 500,000–850,000, 500,000–800,000, 500,000–750,000, 500,000–700,000, 600,000–900,000, 600,000– 850,000, 600,000~800,000, 600,000~750,000, 600,000~700,000, 650,000~900,000, 650,000~850,000, 650,000~800,000, 650,000~750,000, or 650,000~700,000.

[0032] If the weight-average molecular weight of the second peak of the chloroprene polymer or the weight-average molecular weight of the toluene-soluble component in polymer B is 7,000 or more, a good impregnation-molded article can be obtained. From the viewpoint of easily obtaining a good impregnation-molded article, the weight-average molecular weight of the second peak of the chloroprene polymer and the weight-average molecular weight of the toluene-soluble component in polymer B can be 7,500 or more, 8,000 or more, 10,000 or more, 12,000 or more, 15,000 or more, 16,000 or more, or 17,000 or more. From the viewpoint of easily obtaining excellent elongation at break, the weight-average molecular weight of the second peak of the chloroprene polymer and the weight-average molecular weight of the toluene-soluble component in polymer B can be 30,000 or more, 50,000 or more, or 70,000 or more.

[0033] Excellent flexibility can be obtained if the weight-average molecular weight of the second peak of the chloroprene polymer or the weight-average molecular weight of the toluene-soluble component in polymer B is 80,000 or less. From the viewpoint of easily obtaining excellent flexibility, the weight-average molecular weight of the second peak of the chloroprene polymer and the weight-average molecular weight of the toluene-soluble component in polymer B can be 70,000 or less, 50,000 or less, 30,000 or less, 20,000 or less, 18,000 or less, 17,000 or less, 16,000 or less, or 15,000 or less. From the viewpoint of easily obtaining excellent tensile strength, the weight-average molecular weight of the second peak of the chloroprene polymer and the weight-average molecular weight of the toluene-soluble component in polymer B can be 12,000 or less, 10,000 or less, 8,000 or less, or 7,500 or less.

[0034] From these perspectives, the weight-average molecular weight of the second peak of the chloroprene polymer and the weight-average molecular weight of the toluene-soluble component in polymer B can be 7,000–50,000, 7,000–30,000, 7,000–20,000, 7,000–17,000, 10,000–80,000, 10,000–50,000, 10,000–30,000, 10,000–20,000, 10,000–17,000, 15,000–80,000, 15,000–50,000, 15,000–30,000, 15,000–20,000, or 15,000–17,000.

[0035] From the viewpoint of easily obtaining excellent flexibility and tensile strength, the toluene-insoluble content of polymer A can be 70% by mass or more, 75% by mass or more, 80% by mass or more, or 85% by mass or more. The toluene-insoluble content of polymer A can also be 90% by mass or more, or 95% by mass or more. From the viewpoint of easily obtaining excellent flexibility and tensile strength, the toluene-insoluble content of polymer A can be 95% by mass or less, 90% by mass or less, or 85% by mass or less. From these viewpoints, the toluene-insoluble content of polymer A can be 70–95% by mass, 70–90% by mass, 70–85% by mass, 80–95% by mass, 80–90% by mass, 80–85% by mass, 85–95% by mass, or 85–90% by mass.

[0036] From the viewpoint of easily obtaining excellent flexibility and tensile strength, the toluene-insoluble content of polymer B can be less than 5% by mass, less than 4% by mass, less than 3% by mass, less than 2% by mass, or less than 1% by mass. From the viewpoint of easily obtaining excellent flexibility and tensile strength, the toluene-insoluble content of polymer B can be greater than 0% by mass, greater than 0.5% by mass, or greater than 1% by mass. From these viewpoints, the toluene-insoluble content of polymer B can be greater than 0% by mass and less than 5% by mass, greater than 0% by mass and less than 3% by mass, greater than 0% by mass and less than 2% by mass, greater than 0% by mass and less than 1% by mass, 0.5–5% by mass, 0.5–3% by mass, 0.5–2% by mass, 0.5–1% by mass, 1–5% by mass, 1–3% by mass, or 1–2% by mass.

[0037] From the viewpoint of easily obtaining excellent flexibility and tensile strength, based on the total of polymer A and polymer B, the proportion of polymer A, in terms of solid content, can be within the following ranges: The proportion of polymer A can be 70% by mass or more, 75% by mass or more, 80% by mass or more, or 85% by mass or more. The proportion of polymer A can be 95% by mass or less, 90% by mass or less, 85% by mass or less, 80% by mass or less, or 75% by mass or less. From these viewpoints, the proportion of polymer A can be 70–95% by mass, 70–90% by mass, 70–85% by mass, or 75–85% by mass.

[0038] Homopolymers of chloroprene can be obtained by polymerizing chloroprene alone. Copolymers of chloroprene and 2,3-dichloro-1,3-butadiene are polymers having chloroprene and 2,3-dichloro-1,3-butadiene as monomer units, and can be obtained by polymerizing a monomer composition containing chloroprene and 2,3-dichloro-1,3-butadiene.

[0039] Copolymers of chloroprene and 2,3-dichloro-1,3-butadiene can contain monomer units of monomers other than chloroprene and 2,3-dichloro-1,3-butadiene. Examples of such monomers include esters of (meth)acrylic acid (methyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, etc.), hydroxyalkyl esters of (meth)acrylic acid (2-hydroxymethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, etc.), (meth)acrylic acid, 1-chloro-1,3-butadiene, butadiene, isoprene, ethylene, styrene, (meth)acrylonitrile, etc. On the other hand, copolymers of chloroprene and 2,3-dichloro-1,3-butadiene may also be copolymers that do not contain monomer units other than chloroprene and 2,3-dichloro-1,3-butadiene, and may be copolymers formed substantially from monomer units of chloroprene and monomer units of 2,3-dichloro-1,3-butadiene.

[0040] In copolymers of polymer A or polymer B with 2,3-dichloro-1,3-butadiene, from the viewpoint of easily producing impregnated molded articles exhibiting excellent flexibility, the proportion of chloroprene (monomer) relative to 100 parts by mass of monomer (total 100 parts by mass of monomers (raw material monomers) used to obtain the chloroprene polymer, or total 100 parts by mass of chloroprene and 2,3-dichloro-1,3-butadiene, hereinafter the same) can be within the following ranges: The proportion of chloroprene can be 80 parts by mass or more, 85 parts by mass or more, 88 parts by mass or more, or 90 parts by mass or more. The proportion of chloroprene can be 99 parts by mass or less, 98 parts by mass or less, 97 parts by mass or less, 95 parts by mass or less, 94 parts by mass or less, 92 parts by mass or less, or 91 parts by mass or less. From these perspectives, the proportion of chloroprene can be 80–99 parts by mass, 80–98 parts by mass, 80–95 parts by mass, 80–92 parts by mass, 85–99 parts by mass, 85–98 parts by mass, 85–95 parts by mass, 85–92 parts by mass, 90–99 parts by mass, 90–98 parts by mass, 90–95 parts by mass, or 90–92 parts by mass.

[0041] In polymer A or polymer B, from the viewpoint of easily producing an impregnated molded article with excellent flexibility, the proportion of 2,3-dichloro-1,3-butadiene (monomer) copolymerized with chloroprene relative to 100 parts by mass of monomer can be within the following ranges: The proportion of 2,3-dichloro-1,3-butadiene can be 1 part by mass or more, 2 parts by mass or more, 3 parts by mass or more, 5 parts by mass or more, 6 parts by mass or more, 8 parts by mass or more, or 9 parts by mass or more. The proportion of 2,3-dichloro-1,3-butadiene can be 20 parts by mass or less, 15 parts by mass or less, 12 parts by mass or less, or 10 parts by mass or less. From these perspectives, the proportion of 2,3-dichloro-1,3-butadiene can be 1–20 parts by mass, 2–20 parts by mass, 5–20 parts by mass, 8–20 parts by mass, 1–15 parts by mass, 2–15 parts by mass, 5–15 parts by mass, 8–15 parts by mass, 1–10 parts by mass, 2–10 parts by mass, 5–10 parts by mass, or 8–10 parts by mass. The proportion of 2,3-dichloro-1,3-butadiene can be determined by measuring the pyrolysis gas chromatography of the polymer, for example, under the following measurement conditions.

[0042] • Column used: DB-5 0.25mmφ×30m (film thickness 1.0μm)

[0043] • Column temperature: 50℃→10℃ / min→120℃→25℃ / min→300℃

[0044] Injection port temperature: 270℃

[0045] • Detector temperature: 280℃

[0046] • Sample size: 0.05 mg

[0047] In the manufacture of chloroprene polymers, polymerization methods such as emulsion polymerization, solution polymerization, suspension polymerization, and bulk polymerization can be used to polymerize the raw material monomers. Among these polymerization methods, emulsion polymerization is preferred because it has various advantages such as easy control, easy removal of the polymer from the liquid after polymerization, and relatively fast polymerization speed.

[0048] Emulsion polymerization is a type of free radical polymerization, for example, by adding raw monomers, chain transfer agents, water, alkali (e.g., metal hydroxides such as potassium hydroxide and sodium hydroxide), emulsifiers (dispersants), reducing agents (e.g., sodium bisulfite), polymerization initiators, etc., into a reaction vessel to carry out polymerization.

[0049] Regarding the chain transfer agent, the chain transfer agent commonly used in the emulsion polymerization of chloroprene can be used. Specific examples of chain transfer agents include long-chain alkyl thiols such as n-dodecyl mercaptan and tert-dodecyl mercaptan; and dialkyl xanthates such as diisopropyl disulfide and diethyl disulfide. One chain transfer agent can be used alone or in combination of two or more. In the polymerization of polymer A or polymer B, the amount of chain transfer agent used is preferably 0.01 to 10 parts by mass relative to 100 parts by mass of monomer. In the polymerization of polymer A, the amount of chain transfer agent used relative to 100 parts by mass of monomer can be 0.01 to 1 part by mass, 0.01 to 0.1 parts by mass, 0.01 to 0.05 parts by mass, 0.02 to 1 part by mass, 0.02 to 0.1 parts by mass, or 0.02 to 0.05 parts by mass. In the polymerization of polymer B, the amount of chain transfer agent used relative to 100 parts by mass of monomer can be 1-10 parts by mass, 1-8 parts by mass, 1-5 parts by mass, 3-10 parts by mass, 3-8 parts by mass, or 3-5 parts by mass.

[0050] Examples of emulsifiers include anionic emulsifiers and nonionic emulsifiers. Examples of anionic emulsifiers include fatty acid salts such as potassium tallow fatty acid, partially hydrogenated potassium tallow fatty acid, potassium oleate, and sodium oleate; resin salts such as potassium rosinate, sodium rosinate, hydrogenated potassium rosinate, and hydrogenated sodium rosinate; alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate; and sodium salts of β-naphthalenesulfonic acid formaldehyde condensate. Examples of nonionic emulsifiers include polyethylene glycol ester type emulsifiers and polyvinyl alcohol. Among these, anionic emulsifiers are preferred, and at least one selected from the group consisting of potassium rosinate and sodium rosinate is more preferred. One type of emulsifier can be used alone or in combination of two or more types. In the polymerization of polymer A or polymer B, the amount of emulsifier used is preferably 1.0 to 6.5 parts by mass relative to 100 parts by mass of the monomer.

[0051] As polymerization initiators, inorganic peroxides such as potassium persulfate, ammonium persulfate, sodium persulfate, and hydrogen peroxide, and organic peroxides such as benzoyl peroxide can be used. One polymerization initiator can be used alone or in combination of two or more. In the polymerization of polymer A or polymer B, the amount of polymerization initiator used is preferably 0.01 to 10 parts by mass relative to 100 parts by mass of monomer.

[0052] In the polymerization of polymer A or polymer B, the amount of water used in emulsion polymerization is preferably 50 to 300 parts by mass relative to 100 parts by mass of monomer, more preferably 80 to 150 parts by mass.

[0053] In the polymerization of polymer A or polymer B, the polymerization temperature is not particularly limited. From the viewpoint of easily maintaining the flexibility and long-term stability of the chloroprene polymer, the temperature range can be 5-55℃, 10-45℃, 15-45℃, 15-40℃, 15-35℃, or 15-30℃.

[0054] In the polymerization of polymer A or polymer B, the polymerization rate (polymerization conversion rate) of the raw material monomers can be 50–95%, 60–95%, 70–95%, 80–95%, 50–90%, 60–90%, 70–90%, 80–90%, 50–80%, 60–80%, 70–80%, 50–70%, or 60–70%. By keeping the polymerization rate within this range, the solid composition of the chloroprene polymer and the polymerization time during manufacturing become appropriate, resulting in excellent productivity.

[0055] As a polymerization terminator added when the polymerization rate of the raw material monomers reaches the target polymerization rate to stop the polymerization, for example, thiodiphenylamine, 4-tert-butylcatechol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), diethylhydroxyamine, etc. can be used.

[0056] After removing unreacted monomers following polymerization, the concentration of the solid component can be adjusted to an optimal range through a concentration operation. In the polymerization of polymer A or polymer B, the concentration of the solid component is preferably in the range of 45–65% by mass.

[0057] One embodiment of the method for manufacturing the chloroprene polymer according to this embodiment can be as follows: the manufacturing method includes a step of mixing polymer A and polymer B, wherein polymer A is obtained by polymerizing chloroprene and 2,3-dichloro-1,3-butadiene in the presence of a chain transfer agent, water (e.g., pure water), alkali, emulsifier, reducing agent, and polymerization initiator at a polymerization temperature of 10-45°C and a polymerization rate of 80-95%, and polymer B is obtained by polymerizing 90-100 parts by mass of chloroprene in the presence of 1-10 parts by mass of a chain transfer agent, water (e.g., pure water), alkali, emulsifier, reducing agent, and polymerization initiator at a polymerization temperature of 10-45°C and a polymerization rate of 60-90%, wherein the proportion of 2,3-dichloro-1,3-butadiene in the polymerization of polymer B is 10 parts by mass or less (e.g., 0-10 parts by mass). In this method, the total of polymer A and polymer B is used as the basis, and the proportion of polymer A, based on solid components, can be 70-95% by mass.

[0058] The numerical range for the polymerization temperature of polymer A or polymer B can be any of the numerical ranges described above regarding the polymerization temperature of the chloroprene polymer according to this embodiment. The numerical range for the polymerization rate of polymer A or polymer B can be any of the numerical ranges described above regarding the polymerization rate of the chloroprene polymer according to this embodiment. The numerical range for the amount of chain transfer agent used in the polymerization of polymer B can be any of the numerical ranges described above regarding the amount of chain transfer agent used in the chloroprene polymer according to this embodiment. The proportion of 2,3-dichloro-1,3-butadiene in the polymerization of polymer B can be 1 part by mass or more, 2 parts by mass or more, 3 parts by mass or more, 5 parts by mass or more, 6 parts by mass or more, 8 parts by mass or more, or 9 parts by mass or more. The numerical range for the proportion of polymer A can be any of the numerical ranges described above regarding the proportion of polymer A in the chloroprene polymer according to this embodiment.

[0059] The chloroprene polymer composition described in this embodiment contains the chloroprene polymer described in this embodiment. The chloroprene polymer composition described in this embodiment may contain pH adjusters, freeze stabilizers, emulsion stabilizers, viscosity modifiers, anti-aging agents, preservatives, etc.

[0060] The chloroprene polymer composition according to this embodiment may contain additives such as vulcanizing agents, vulcanization accelerators, anti-aging agents (antioxidants, such as anti-ozone aging agents), fillers, plasticizers, pigments, colorants, wetting agents, and defoamers. The chloroprene polymer composition according to this embodiment may be a mixture for impregnation molding containing chloroprene polymer and these additives. Regarding the chloroprene polymer composition according to this embodiment, as a method prior to mixing these additives, it may also be that it does not contain at least one additive selected from the group consisting of vulcanizing agents, vulcanization accelerators, anti-aging agents, fillers, plasticizers, pigments, colorants, wetting agents, and defoamers.

[0061] Examples of vulcanizing agents include sulfur (molecular sulfur, such as cyclic sulfur like S8); metal oxides such as zinc oxide, lead oxide, and lead tetroxide; and magnesium oxide. From the viewpoints of easily and sufficiently achieving crosslinking, easily and ideally obtaining the tensile strength and modulus of the impregnated molded body, and easily obtaining the ideal tactile feel of the impregnated molded body, the content of the vulcanizing agent can be 0.5 to 10 parts by mass relative to 100 parts by mass of the solid component of the chloroprene polymer. One crosslinking agent can be used alone or in combination of two or more.

[0062] Examples of vulcanization accelerators include thiuram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthate-based, and thiazole-based accelerators. From the viewpoint of easily obtaining appropriate strength, the vulcanization accelerator can be 0.5 to 5 parts by mass relative to 100 parts by mass of the solid component of the chloroprene polymer. One vulcanization accelerator can be used alone or in combination of two or more.

[0063] Examples of anti-aging agents include octyl diphenylamine, p-(p-toluenesulfonamide)diphenylamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, N,N'-diphenyl-p-phenylenediamine (DPPD), and N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), among other diphenylamine compounds. Examples of anti-ozone aging agents include N,N'-diphenyl-p-phenylenediamine (DPPD) and N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD). When appearance (especially color) or hygiene is a concern, such as with medical gloves, hindered phenolic anti-aging agents can be used. From the viewpoint of easily and sufficiently obtaining anti-aging effects, the content of the anti-aging agent can be 0.1 to 5 parts by weight relative to 100 parts by weight of the solid component of the chloroprene polymer.

[0064] <Sulfides, Impregnated Molded Articles and Their Manufacturing Methods>

[0065] A sulfide can be obtained by vulcanizing the chloroprene polymer composition according to this embodiment. The sulfide according to this embodiment is a sulfide of the chloroprene polymer composition according to this embodiment, obtained by vulcanizing the chloroprene polymer composition according to this embodiment. The sulfide according to this embodiment can be in the form of a film.

[0066] The impregnated molded body involved in this embodiment is an impregnated molded body of the chloroprene polymer composition involved in this embodiment. The impregnated molded body involved in this embodiment is an impregnated molded body using the chloroprene polymer composition involved in this embodiment, obtained by impregnating the chloroprene polymer composition involved in this embodiment. The impregnated molded body involved in this embodiment can be an impregnated molded film (film-like impregnated molded body), which can be an impregnated molded film formed on a substrate. The impregnated molded body involved in this embodiment has very high flexibility, and also has sufficient tensile strength and elongation at break for an impregnated molded body. The impregnated molded body involved in this embodiment can be a molded body of a sulfide involved in this embodiment. The impregnated molded body involved in this embodiment can be a glove, balloon, tube, or boot.

[0067] The thickness (e.g., minimum thickness) of the impregnated molded body (e.g., impregnated molded film) can be within the following ranges: The thickness of the impregnated molded body can be 0.01 mm or more, 0.05 mm or more, 0.10 mm or more, 0.15 mm or more, or 0.20 mm or more. The thickness of the impregnated molded body can be 0.50 mm or less, 0.45 mm or less, 0.40 mm or less, 0.35 mm or less, 0.30 mm or less, or 0.25 mm or less. From these perspectives, the thickness of the impregnated molded body can be 0.01–0.50 mm, 0.10–0.50 mm, 0.10–0.30 mm, or 0.10–0.25 mm. The thickness of the impregnated molded body can be adjusted by the impregnation time of the molding die in the chloroprene polymer composition, the concentration of the solid component of the chloroprene polymer composition, etc. If it is desired to reduce the thickness of the impregnated molded body, the impregnation time can be shortened, or the concentration of the solid component of the chloroprene polymer composition can be reduced.

[0068] In the method for manufacturing the impregnated molded body according to this embodiment, the chloroprene polymer composition according to this embodiment is impregnated. Known methods can be used as the molding method for manufacturing the impregnated molded body according to this embodiment, including simple impregnation, coagulant impregnation, thermosensitive impregnation, electrodeposition, etc. From the viewpoint of ease of manufacturing and ease of obtaining an impregnated molded body of a certain thickness, the coagulant impregnation method can be used. Specifically, a molding die coated with a coagulant is impregnated in the chloroprene polymer composition, causing the chloroprene polymer composition to solidify. Then, water-soluble impurities are removed by leaching, followed by drying and further vulcanization to form an impregnated molded film (rubber film), which is then demolded. Thus, a film-like impregnated molded body can be obtained.

[0069] Example

[0070] The present invention will now be described in more detail based on embodiments and comparative examples, but the present invention is not limited to these embodiments. It should be noted that the evaluation method is described below.

[0071] <Evaluation Methods>

[0072] (GPC determination of toluene-soluble components)

[0073] 20 mg of the dried product obtained by freeze-drying chloroprene polymers A, B, or a mixture of chloroprene polymers was dissolved in 20 ml of toluene for at least 12 hours to separate the sol. The separated sol was then dissolved in 20 ml of THF solution to obtain the sample, which was then determined by gel permeation chromatography (GPC) under the following conditions. The weight-average molecular weight (Mw) was calculated based on polystyrene.

[0074] Assay apparatus: TOSOH Corporation, gel permeation chromatography (HLC-8320)

[0075] Column: TOSOH Corporation, TSKgel ALPHA-M

[0076] Eluent: THF (LiBr: 10mM)

[0077] Elution buffer flow rate: 1.0 ml / min

[0078] Column temperature: 40℃

[0079] Detection method: Differential refractive index (RI) meter

[0080] Standard curve: made using standard polystyrene.

[0081] (Toluene-insoluble components)

[0082] 1 g of the dried product obtained by freeze-drying chloroprene polymers A, B, or a mixture of chloroprene polymers was cut into 2 mm square pieces to obtain small flakes. These flakes were then placed in a conical beaker and dissolved in toluene for 16 hours. The mixture was then centrifuged, and the gel component was separated using a 200-mesh metal mesh. After drying, the mass of the resulting dried product was determined, and the toluene-insoluble component was calculated.

[0083] (Evaluation of membrane thickness)

[0084] Using a test piece thickness gauge (manufactured by Polymer Instruments Co., Ltd., trade name: ASKER SDA-12), the thickness (film thickness) at three points in the center of the evaluation film was measured, and the minimum thickness was taken as the thickness of the evaluation film.

[0085] (Evaluating the physical properties of the membrane)

[0086] The modulus at 100% elongation, tensile strength, and elongation at break of the evaluation membrane were measured according to JIS K 6251. A modulus at 100% elongation of 0.70 MPa or less and a tensile strength of 17.0 MPa or more, which are indicators of flexibility, were considered good.

[0087] <Preparation of Chloroprene Polymers>

[0088] (Example 1)

[0089] A mixture was prepared by mixing 90.5 parts by weight of chloroprene (monomer), 9.5 parts by weight of 2,3-dichloro-1,3-butadiene (monomer), 0.032 parts by weight of n-dodecyl mercaptan, 90 parts by weight of purified water, 4.5 parts by weight of rosin (manufactured by Arakawa Chemical Industry Co., Ltd., trade name: HARTALLR-WW), 0.78 parts by weight of potassium hydroxide, 0.40 parts by weight of sodium salt of β-naphthalenesulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), and 0.40 parts by weight of sodium bisulfite. After adding 0.1 parts by weight of potassium persulfate as a polymerization initiator, polymerization was carried out at a polymerization temperature of 15°C under a nitrogen atmosphere. At the polymerization point of 85%, 0.01 parts by weight of diethylhydroxylamine as a polymerization terminator was added to stop the polymerization. By removing unreacted monomers and concentrating the mixture, a chloroprene polymer A with a solid content of 60% was obtained. Gel permeation chromatography (GPC) was performed to determine the toluene-soluble component of chloroprene polymer A. The results showed that the weight-average molecular weight (Mw) of the toluene-soluble component was 607,000. Additionally, the toluene-insoluble component of chloroprene polymer A was 85% by mass.

[0090] A mixture of 100 parts by weight of chloroprene (monomer), 5.0 parts by weight of n-dodecyl mercaptan, 90 parts by weight of purified water, 5.3 parts by weight of disproportionated rosin (manufactured by Arakawa Chemical Industry Co., Ltd., trade name: RO NDIS K-25), 0.78 parts by weight of potassium hydroxide, 0.40 parts by weight of sodium salt of β-naphthalenesulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), and 0.50 parts by weight of sodium bisulfite was prepared. After adding 0.1 parts by weight of potassium persulfate as a polymerization initiator, polymerization was carried out at a polymerization temperature of 40°C under a nitrogen atmosphere. At the point where the polymerization rate reached 60%, 0.01 parts by weight of diethylhydroxylamine as a polymerization terminator was added to stop the polymerization. By removing unreacted monomers and concentrating the mixture, a chloroprene polymer B with a solid content of 60% was obtained. Gel permeation chromatography (GPC) was performed to determine the toluene-soluble components of chloroprene polymer B. The weight-average molecular weight (Mw) of the toluene-soluble components was 16,000. Additionally, the toluene-insoluble component of chloroprene polymer B was 1% by mass.

[0091] Next, these chloroprene polymers A and B were mixed at a ratio of A / B = 75 / 25 (mass ratio of solid components) to obtain a mixed chloroprene polymer. Gel permeation chromatography (GPC) was performed to determine the toluene-soluble components of the mixed chloroprene polymer. The results confirmed a first peak with a weight-average molecular weight (Mw) of 680,000 and a second peak with a weight-average molecular weight (Mw) of 17,000. Furthermore, the toluene-insoluble component of the mixed chloroprene polymer was 70% by mass.

[0092] (Example 2)

[0093] The monomers of chloroprene polymer B in Example 1 were changed to 90.5 parts by mass of chloroprene and 9.5 parts by mass of 2,3-dichloro-1,3-butadiene. Otherwise, a mixed chloroprene polymer was prepared by the same procedure as in Example 1. The various measurement results of chloroprene polymers A, B and the mixed chloroprene polymer are shown in Table 1.

[0094] (Example 3)

[0095] The polymerization temperature of chloroprene polymer A in Example 1 was changed to 40°C. Otherwise, a mixed chloroprene polymer was prepared using the same steps as in Example 1. The various measurement results of chloroprene polymers A, B, and the mixed chloroprene polymer are shown in Table 1.

[0096] (Examples 4 and 5)

[0097] In Examples 4 and 5, the chain transfer agent of chloroprene polymer A in Example 1 was changed to 0.016 parts by mass and 0.054 parts by mass, respectively. Otherwise, mixed chloroprene polymers were prepared using the same steps as in Example 1. The various measurement results of chloroprene polymers A, B, and the mixed chloroprene polymers are shown in Table 1.

[0098] (Example 6)

[0099] The polymerization temperature of chloroprene polymer B from Example 1 was changed to 15°C. Otherwise, a mixed chloroprene polymer was prepared using the same steps as in Example 1. The various measurement results of chloroprene polymers A, B, and the mixed chloroprene polymer are shown in Table 1.

[0100] (Examples 7 and 8)

[0101] In Examples 7 and 8, the chain transfer agent of chloroprene polymer B in Example 1 was changed to 1.0 parts by mass and 10.0 parts by mass, respectively. Otherwise, a mixed chloroprene polymer was prepared using the same steps as in Example 1. The various measurement results of chloroprene polymers A, B, and the mixed chloroprene polymer are shown in Table 2.

[0102] (Examples 9-11)

[0103] The mixing ratio of chloroprene polymer A and chloroprene polymer B from Example 1 was changed to 95 / 5, 85 / 15, and 70 / 30 (mass ratio) in Examples 9-11, respectively. Otherwise, mixed chloroprene polymers were prepared using the same procedures as in Example 1. The various measurement results for chloroprene polymers A, B, and the mixed chloroprene polymers are shown in Table 2.

[0104] (Comparative Example 1)

[0105] The mixing ratio of chloroprene polymer A and chloroprene polymer B from Example 1 was changed to 100 / 0 (mass ratio), but the mixed chloroprene polymer was prepared using the same steps as in Example 1. Various measurement results for chloroprene polymer A are shown in Table 3.

[0106] (Compare Examples 2 and 3)

[0107] The chain transfer agent of chloroprene polymer A in Example 1 was changed to 0.01 parts by mass and 0.08 parts by mass in Comparative Examples 2 and 3, respectively. Otherwise, mixed chloroprene polymers were prepared by the same procedure as in Example 1. The various measurement results of chloroprene polymers A, B and mixed chloroprene polymers are shown in Table 3.

[0108] (Comparative Example 4)

[0109] The polymerization rate of chloroprene polymer A in Example 1 was changed to 45%, and a mixed chloroprene polymer was prepared using the same steps as in Example 1. The various measurement results for chloroprene polymers A, B, and the mixed chloroprene polymer are shown in Table 3.

[0110] (Compare Examples 5 and 6)

[0111] The chain transfer agent of chloroprene polymer B in Example 1 was changed to 0.25 parts by mass and 13.0 parts by mass in Comparative Examples 5 and 6, respectively. Otherwise, mixed chloroprene polymers were prepared by the same procedure as in Example 1. The various measurement results of chloroprene polymers A, B and mixed chloroprene polymers are shown in Table 3.

[0112] <Preparation of Chloroprene Polymer Compositions for Molding>

[0113] Using a ceramic ball mill, 1 part by weight of sulfur, 2 parts by weight of zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., trade name: Zinc Oxide 2 Type), 2 parts by weight of vulcanization accelerator (manufactured by Ouchi Shinsei Chemical Co., Ltd., trade name: Nocceler BZ), 2 parts by weight of anti-aging agent (manufactured by OMNOVA SOLUTIONS, trade name: Wingstay-L), 0.1 parts by weight of sodium salt of β-naphthalenesulfonic acid formaldehyde condensate (manufactured by Kao Corporation, trade name: Demol N), and 10.7 parts by weight of water were mixed for 16 hours at 20°C to prepare an aqueous dispersion with a solid component concentration of 40%. Then, 7.1 parts by weight of the solid component of this aqueous dispersion were mixed with 100 parts by weight of the solid component of the above-mentioned mixed chloroprene polymer, and water was added to adjust the overall solid component concentration to 30% by weight, thereby producing a chloroprene polymer composition for molding.

[0114] <Evaluation of membrane fabrication>

[0115] A coagulation solution was prepared by mixing 61 parts by mass of water, 36 parts by mass of potassium nitrate tetrahydrate, and 3 parts by mass of calcium carbonate. A ceramic cylinder (material: ceramic, manufactured by Shinko Ind. Ltd.) with an outer diameter of 50 mm was immersed in this coagulation solution for 1 second, and then removed. The cylinder was dried at room temperature (23°C) for 3 minutes, followed by drying at 70°C for 1 minute. Then, the cylinder was immersed in the aforementioned molding chloroprene polymer composition for 2 minutes. Next, it was dried at 130°C for 3 minutes, and then cleaned by immersing in warm water at 40°C for 1 minute. Then, it was vulcanized at 130°C for 4 hours, thereby forming an evaluation film (impregnated molded body, vulcanized film) on the outer circumferential surface of the cylinder. The evaluation film was peeled off from the outer circumferential surface of the cylinder and evaluated. However, in Comparative Example 5, the impregnated molded body had strong adhesion and could not be peeled off from the cylinder; therefore, it was deemed unsuitable for fabrication.

[0116] <Results>

[0117] By comparing the various examples with the comparative examples, it can be seen that if the chloroprene polymer has a first peak with a weight-average molecular weight of 500,000 to 900,000 and a second peak with a weight-average molecular weight of 7,000 to 80,000 in the gel permeation chromatography (GPC) determination of the toluene-soluble components, and the toluene-insoluble components of the chloroprene polymer are 60% by mass or more, then it has a low modulus at 100% elongation, excellent flexibility, and exhibits high breaking strength.

[0118] [Table 1]

[0119]

[0120] [Table 2]

[0121]

[0122] [Table 3]

[0123]

Claims

1. A chloroprene polymer, which, in the gel permeation chromatography determination of toluene-soluble components, exhibits a first peak with a weight-average molecular weight of 500,000–900,000 and a second peak with a weight-average molecular weight of 7,000–80,000. In the chloroprene polymer, the toluene-insoluble component is 60% or more by mass. The chloroprene polymer is a mixture of polymer A and polymer B, wherein polymer A contains a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene, and polymer B contains at least one selected from the group consisting of homopolymers of chloroprene and copolymers of chloroprene and 2,3-dichloro-1,3-butadiene. The weight-average molecular weight of the toluene-soluble component in polymer A is 500,000 to 900,000. The weight-average molecular weight of the toluene-soluble component in polymer B is 7,000 to 80,000. The toluene-insoluble component of polymer A is 70% or more by mass. The toluene-insoluble component of polymer B is less than 5% by mass. in, Based on the total of polymer A and polymer B, the proportion of polymer A is 70-95% by mass in terms of solid components.

2. A chloroprene polymer composition comprising the chloroprene polymer of claim 1.

3. The impregnated molded article of the chloroprene polymer composition according to claim 2.

4. The impregnation molded body as described in claim 3, wherein it is a glove, a balloon, a conduit, or a boot.

5. The method for manufacturing the chloroprene polymer according to claim 1, comprising the step of mixing polymer A and polymer B. Polymer A is obtained by polymerizing chloroprene and 2,3-dichloro-1,3-butadiene in the presence of a chain transfer agent, water, alkali, emulsifier, reducing agent, and polymerization initiator, at a polymerization temperature of 10-45°C and a polymerization rate of 80-95%. The polymer B is obtained by polymerizing 90-100 parts by mass of chloroprene in the presence of 1-10 parts by mass of chain transfer agent, water, alkali, emulsifier, reducing agent and polymerization initiator, at a polymerization temperature of 10-45°C and a polymerization rate of 60-90%. The proportion of 2,3-dichloro-1,3-butadiene in the polymerization of polymer B is less than 10 parts by mass.

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