Chloroprene-based polymer latex, adhesive agent composition, composition for forming dip-molded article, dip-molded article, and method for producing chloroprene-based polymer latex

Abstract

Provided is a chloroprene-based polymer latex having adequate mechanical stability. The present invention provides a chloroprene-based polymer latex including micelles each containing a chloroprene-based polymer and an emulsifier. When a volume-based particle size distribution of the micelles is measured by a dynamic light scattering method in a range of 1-10,000 nm to obtain a histogram in which the horizontal axis represents the particle size represented by common logarithm and has 45 classes obtained by equally dividing the horizontal axis in the range of 1-10,000 nm into 45 portions, and in which the vertical axis represents a volume distribution, and when dk nm represents the particle size class value of class k having the k-th smallest particle size, Vk% represents the volume distribution of class k, s% represents the solid content concentration of the chloroprene-based polymer latex, ρLx g / cm3 represents the specific gravity of the chloroprene-based polymer latex, ρCR g / cm3 represents the specific gravity of the chloroprene-based polymer, n mol represents the amount of the emulsifier contained in 1 L of the chloroprene-based polymer latex, and NA represents the Avogadro's number, the chloroprene-based polymer latex satisfies the following formula.

Description

Chloroprene polymer latex, adhesive composition, composition for forming dip-molded body, dip-molded body, and method for producing chloroprene polymer latex

[0001] The present invention relates to a chloroprene polymer latex, an adhesive composition, a composition for forming a dip-molded article, a dip-molded article, and a method for producing a chloroprene polymer latex.

[0002] Chloroprene-based rubbers have excellent mechanical properties, ozone resistance, and chemical resistance, and by utilizing these properties, they are used in a wide range of fields, such as automobile parts, adhesives, various industrial rubber parts, etc. For example, Patent Document 1 discloses a method for producing a chloroprene-based polymer, in which chloroprene or chloroprene and a monomer copolymerizable with chloroprene are polymerized in an aqueous medium in the presence of a surfactant, to which the surfactant has been added at a concentration less than the critical micelle concentration (CMC).

[0003] WO2011 / 004860

[0004] However, it has been difficult to obtain a chloroprene polymer latex having adequate mechanical stability.

[0005] The present invention has been made in view of the above circumstances, and aims to provide a chloroprene polymer latex having appropriate mechanical stability.

[0006] According to the present invention, there is provided a chloroprene polymer latex containing micelles containing a chloroprene polymer and an emulsifier, wherein the volume-based particle size distribution of the micelles is measured by dynamic light scattering in the range of 1 nm to 10,000 nm to obtain a histogram, the horizontal axis of the histogram representing particle diameters expressed in common logarithms, the horizontal axis having 45 classes obtained by equally dividing the range of 1 nm to 10,000 nm into 45 classes, the vertical axis representing volume distribution, and the class value of the particle diameter of the class k having the kth smallest particle diameter is represented by d ｋ The volume distribution of nm class k is V ｋ , the solid content of the chloroprene polymer latex is S, and the specific gravity of the chloroprene polymer latex is ρ Ｌｘ　 g / cm ３ , the specific gravity of the chloroprene polymer is ρ ＣＲ　 g / cm３ The amount of emulsifier contained in 1 L of the chloroprene polymer latex is n mol, Avogadro's number is N Ａ When the above formula is satisfied, a chloroprene polymer latex is provided which satisfies the following formula:

[0007]

[0008] As a result of extensive investigations, the present inventors have found a chloroprene polymer latex having appropriate mechanical stability by defining the ratio of the micelle surface area to the amount of an emulsifier, which is calculated by a specific formula obtained from the particle size distribution, and have thus completed the present invention.

[0009] Various embodiments of the present invention will be exemplified below. The embodiments shown below can be combined with each other. [1] A chloroprene polymer latex containing micelles containing a chloroprene polymer and an emulsifier, wherein the volume-based particle size distribution of the micelles is measured by dynamic light scattering in the range of 1 nm to 10,000 nm to obtain a histogram, the horizontal axis of the histogram representing particle diameters expressed in common logarithms, the horizontal axis having 45 classes obtained by dividing the range of 1 nm to 10,000 nm into 45 equal classes, the vertical axis representing volume distribution, and the class value of the particle diameter of the class k having the kth smallest particle diameter being d ｋ The volume distribution of nm class k is V ｋ , the solid content of the chloroprene polymer latex is S, and the specific gravity of the chloroprene polymer latex is ρ Ｌｘ　 g / cm ３ , the specific gravity of the chloroprene polymer is ρ ＣＲ　 g / cm ３ The amount of emulsifier contained in 1 L of the chloroprene polymer latex is n mol, Avogadro's number is N Ａ A chloroprene polymer latex that satisfies the following formula when [2] The chloroprene polymer latex according to [1], wherein D50 obtained from the particle size distribution is 80 to 700 nm. [3] The chloroprene polymer latex according to [1] or [2], wherein the content of the emulsifier is 0.5 to 10.0 parts by mass based on 100 parts by mass of the chloroprene polymer. [4] The chloroprene polymer latex according to any of [1] to [3], wherein the mechanical stability measured for 10 minutes under conditions of a load of 10.0 kg and a rotation speed of 1,000 rpm is 0.1 to 20.0%. [5] The chloroprene polymer latex according to any of [1] to [4], wherein the micelle surface area per 1 L of the chloroprene polymer latex is 30,000 to 100,000 m ２ [6] An adhesive composition comprising the chloroprene polymer latex according to any one of [1] to [5]. [7] A composition for forming a dip-molded body, comprising the chloroprene polymer latex according to any one of [1] to [3]. [8] A dip-molded body made from the composition for forming a dip-molded body according to [7]. [9] A method for producing a chloroprene polymer latex containing micelles containing a chloroprene polymer and an emulsifier, the method comprising: a monomer droplet micro-reducing step, a polymerization step, and an emulsifier additional-adding step; in the monomer droplet micro-reducing step, droplets containing a raw material monomer including a chloroprene monomer are collided with a collision medium in the presence of an initially-added emulsifier to reduce the droplets to an average particle size of 300 nm or less; in the polymerization step, the raw material monomer including the chloroprene monomer is polymerized to obtain a chloroprene polymer; and in the emulsifier additional-adding step, an additionally-added emulsifier is additionally added after the monomer droplet micro-reducing step, and the amount of the additionally-added emulsifier is more than 60% by mass relative to 100% by mass of the total of the initially-added emulsifier and the additionally-added emulsifier.

[0010] The chloroprene polymer latex according to the present invention can provide a chloroprene polymer latex having appropriate mechanical stability. In one embodiment of the present invention, the chloroprene polymer latex can be used in an adhesive composition. In another embodiment of the present invention, the chloroprene polymer latex can be used in a composition for forming a dip-molded product. Because the chloroprene polymer latex has excellent mechanical properties, the adhesive composition and the composition for forming a dip-molded product have excellent stability during the production process, storage, and transportation. Furthermore, an adhesive composition containing the chloroprene polymer latex exhibits excellent spray applicability with little clogging, rapid demulsification after application, and excellent initial adhesive strength. Furthermore, an adhesive composition containing the chloroprene polymer latex exhibits excellent stability and dip-molding properties.

[0011] The present invention will be described in detail below by illustrating embodiments of the present invention. The present invention is not limited by these descriptions. The features of the embodiments of the present invention described below can be combined with each other. Furthermore, each feature can be an invention independently.

[0012] 1. Chloroprene Polymer Latex The chloroprene polymer latex according to the present invention comprises micelles containing a chloroprene polymer and an emulsifier, and has a ratio of the micelle surface area to the amount of the emulsifier, which is calculated by a specific formula using values ​​obtained from a particle size distribution obtained under specific conditions, within a specific range.

[0013] 1.1 Chloroprene-Based Polymer The chloroprene-based polymer according to the present invention refers to a polymer containing a monomer unit (monomer unit = structural unit) derived from 2-chloro-1,3-butadiene (hereinafter also referred to as chloroprene). Examples of the chloroprene-based polymer include a chloroprene homopolymer and a chloroprene copolymer (a copolymer of chloroprene and a monomer copolymerizable with chloroprene). The polymer structure of the chloroprene-based polymer is not particularly limited.

[0014] Commercially available 2-chloro-1,3-butadiene may contain a small amount of 1-chloro-1,3-butadiene as an impurity. 2-chloro-1,3-butadiene containing such a small amount of 1-chloro-1,3-butadiene can also be used as the chloroprene monomer of this embodiment.

[0015] The chloroprene polymer according to one embodiment of the present invention may also have a monomer unit derived from a monomer other than a chloroprene monomer. The monomer other than a chloroprene monomer is not particularly limited as long as it is copolymerizable with the chloroprene monomer, and examples thereof include (meth)acrylic acid esters (methyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc.), hydroxyalkyl (meth)acrylates (2-hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, etc.), unsaturated nitriles (acrylonitrile, methacrylonitrile, ethacrylonitrile, phenylacrylonitrile, etc.), 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, ethylene, styrene, sulfur, etc.

[0016] For example, a chloroprene polymer according to one embodiment of the present invention may contain a diene monomer unit. The content of the diene monomer unit in the chloroprene polymer may be, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30% by mass, or may be within a range between any two of the values ​​exemplified here. Examples of the diene monomer include conjugated diene monomers having 4 to 6 carbon atoms (excluding chloroprene), such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene.

[0017] A chloroprene-based polymer according to one embodiment of the present invention may include chloroprene monomer units and 2,3-dichloro-1,3-butadiene monomer units. The chloroprene-based polymer according to one embodiment of the present invention may contain 0 to 30% by mass of 2,3-dichloro-1,3-butadiene monomer units relative to 100% by mass of the total of the chloroprene monomer units and the 2,3-dichloro-1,3-butadiene monomer units. The content of the 2,3-dichloro-1,3-butadiene monomer units may be, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30% by mass, or may be within a range between any two of the values ​​exemplified here.

[0018] For example, a chloroprene-based polymer according to one embodiment of the present invention may contain an unsaturated nitrile monomer unit. The content of the unsaturated nitrile monomer unit in the chloroprene-based polymer may be, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25% by mass, or may be within a range between any two of the values ​​exemplified here. The chloroprene-based polymer according to one embodiment of the present invention may contain the unsaturated nitrile monomer unit in order to improve the mechanical properties, dynamic properties, abrasion resistance, oil resistance, etc. of a molded article.

[0019] The content of unsaturated nitrile monomer units in a chloroprene polymer can be calculated from the content of nitrogen atoms in the chloroprene polymer. Specifically, the content of nitrogen atoms in 100 mg of chloroprene polymer can be measured using an elemental analyzer (Sumigraph 220F, manufactured by Sumika Chemical Analysis Center, Ltd.), and the content of structural units derived from unsaturated nitrile monomers can be calculated. Elemental analysis can be performed under the following conditions. For example, the electric furnace temperatures are set to 900°C for the reactor, 600°C for the reduction furnace, 70°C for the column, and 100°C for the detector, and oxygen is flowed at 0.2 mL / min as the combustion gas and 80 mL / min as the carrier gas. A calibration curve can be prepared using aspartic acid (10.52%), which has a known nitrogen content, as a standard substance.

[0020] For example, a chloroprene-based polymer according to an embodiment of the present invention may include an aromatic vinyl monomer unit. The content of the aromatic vinyl monomer unit in the chloroprene-based polymer may be, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30% by mass, or may be within a range between any two of the values ​​exemplified here. The aromatic vinyl monomer unit preferably includes styrene.

[0021] The chloroprene polymer latex according to one embodiment of the present invention may contain 70 to 100% by mass of chloroprene monomer units relative to 100% by mass of the chloroprene polymer contained in the chloroprene polymer latex. The content of the chloroprene monomer units may be, for example, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100% by mass, or may be within a range between any two of the values ​​exemplified here.

[0022] The chloroprene polymer latex according to one embodiment of the present invention may contain 0 to 30% by mass of other monomer units than chloroprene monomer units, based on 100% by mass of the chloroprene polymer contained in the chloroprene polymer latex. The content of the other monomer units may be, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30% by mass, or may be within a range between any two of the values ​​exemplified here. The chloroprene polymer according to one embodiment of the present invention may be composed of chloroprene monomer units, or may be composed of chloroprene monomer units and 2,3-dichloro-1,3-butadiene monomer units.

[0023] The chloroprene polymer latex according to one embodiment of the present invention may contain two or more different chloroprene polymers. When the chloroprene polymer latex according to one embodiment of the present invention contains two or more different chloroprene polymers, the content of each monomer unit in the chloroprene polymer means the total content of each monomer unit in each chloroprene polymer relative to 100% by mass of all the chloroprene polymers contained in the chloroprene polymer latex.

[0024] The weight average molecular weight of the chloroprene polymer is, for example, 5×10 ３ g / mol, 10×10 ３ g / mol, 50×10 ３ g / mol, 100×10 ３ g / mol, 300×10 ３ g / mol, 400×10 ３ g / mol, 450×10 ３ g / mol, 500×10 ３ g / mol, 800×10 ３ g / mol, 1000×10 ３ g / mol, 2000×10 ３ g / mol, 3000×10 ３ g / mol, 5000×10 ３ g / mol and may be in the range between any two of the values ​​exemplified herein.

[0025] The number average molecular weight of the chloroprene polymer is, for example, 1 × 10 ３ g / mol, 5 x 10 ３ g / mol, 10×10 ３ g / mol, 50×10 ３ g / mol, 100×10 ３ g / mol, 130×10 ３ g / mol, 200×10 ３ g / mol, 300×10 ３ g / mol, 500×10 ３ g / mol, 800×10 ３ g / mol, 1000×10 ３ g / mol and may be in the range between any two of the values ​​exemplified herein.

[0026] The molecular weight distribution of the chloroprene polymer is 1.0, 1.5, 2.0, 2.5, 3.0, 3.2, 3.4, 3.5, 3.8, 4.0, 5.0, 8.0, or 10, and may be within a range between any two of the numerical values ​​exemplified here.

[0027] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the chloroprene polymer can be measured by gel permeation chromatography (GPC) and converted into polystyrene equivalents. Specifically, they can be measured by the method described in the examples.

[0028] 1.2 Emulsifier The chloroprene polymer latex according to the present invention contains an emulsifier. The emulsifier is not particularly limited, and known emulsifiers commonly used in chloroprene polymerization can be used. Examples of the emulsifier 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 acid salts such as potassium rosinate, sodium rosinate, hydrogenated potassium rosinate, and hydrogenated sodium rosinate; alkyl sulfate salts such as sodium lauryl sulfate; alkyl benzene sulfonates such as sodium dodecyl benzene sulfonate; and sodium salts of β-naphthalene sulfonic acid formalin condensates. Examples of nonionic emulsifiers include polyethylene glycol ester emulsifiers and polyvinyl alcohol. The emulsifier preferably contains at least one of alkyl sulfate salts, alkyl benzene sulfonates, and resin acid salts, and more preferably contains at least one of alkyl sulfate salts and alkyl benzene sulfonates. The number of carbon atoms of the alkyl sulfate ester salt and the alkyl benzene sulfonate salt is, for example, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, or 22, and may be within a range between any two of the values ​​exemplified here.

[0029] The content of the emulsifier per 100 parts by mass of the chloroprene polymer can be 0.5 to 10.0 parts by mass. The content of the emulsifier is, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5.0, 5, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, or 10.0 parts by mass, or may be within a range between any two of the values ​​exemplified here. By setting the content of the emulsifier within the above range, a chloroprene polymer latex with more appropriate mechanical stability can be obtained. Furthermore, by adjusting the amount of the emulsifier, the ratio of the micelle surface area to the amount of emulsifier can be adjusted.

[0030] 1.3 Characteristics of Chloroprene Polymer Latex The chloroprene polymer latex according to the present invention comprises micelles containing the above-mentioned chloroprene polymer and an emulsifier. When a volume-based particle size distribution of micelles in the range of 1 nm to 10,000 nm is measured by dynamic light scattering to obtain a histogram, the chloroprene polymer latex according to the present invention has a ratio of micelle surface area to emulsifier amount calculated by a specific formula using values ​​obtained from the histogram, which falls within a specific range.

[0031] The particle size distribution can be measured by an apparatus capable of measurement by dynamic light scattering (for example, ELSZ Series (manufactured by Otsuka Electronics Co., Ltd.)) using a test solution prepared by diluting the chloroprene polymer latex with distilled water so that the solid content concentration is 0.01% by mass. The histogram has 45 classes obtained by dividing the horizontal axis into 45 equal parts in the range of 1 nm to 10,000 nm, with the horizontal axis representing the particle diameter (nm) expressed in common logarithm. The vertical axis of the histogram represents the volume distribution. When the "micelle surface area per emulsifier molecule" of the chloroprene polymer latex according to the present invention is calculated using the particle diameter class value of each class of the histogram and the volume distribution of each class, the ratio of the micelle surface area to the amount of emulsifier defined by the following formula, the micelle surface area per emulsifier molecule is 0.10 to 0.40 (nm ２ / 1 molecule of emulsifier).

[0032] The micelle surface area per emulsifier molecule is, for example, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, or 0.40 nm ２ / one molecule of emulsifier, and may be within a range between any two of the values ​​exemplified here.

[0033] In the above formula, d ｋ represents the particle size class value (nm) of the particle size class k, which is the kth smallest particle size. Here, the class value can be the median value of each class. For example, if the range of class k is "X ｋ That's all, Y ｋ If "less than" then d ｋ is X ｋ and Y ｋ It can be calculated as the average value of V ｋis the volume distribution of class k, and the volume distribution of class k having the kth smallest particle diameter, i.e., the value on the vertical axis, can be used. The total of the volume distributions of all classes is 1, and the volume distribution of each class k is expressed as a numerical value between 0 and 1. S is the solid content ratio of the chloroprene polymer latex. S is expressed as a numerical value between 0 and 1. S is the ratio of the solid content of the chloroprene polymer latex to the chloroprene polymer latex, and is expressed as a numerical value between 0 and 1. ρ Ｌｘ is the specific gravity (g / cm) of the chloroprene polymer latex ３ ) and can be determined from the mass per unit volume of the chloroprene polymer latex measured at 25°C. ＣＲ is the specific gravity (g / cm) of the chloroprene polymer at 25°C ３ ) and when the chloroprene-based polymer is a chloroprene homopolymer, it is 1.21 g / cm ３ n is the amount (mol) of emulsifier contained in 1 L of chloroprene polymer latex. Ａ Avogadro's number is 6.02 x 10 ２３ mol －１ This can be done.

[0034] The above formula is derived as follows: For class k of the particle size distribution, the "particle volume per micelle in class k" and the "volume of class k in 1 L of micelles" are as follows: Particle volume per micelle in class k: 4 / 3 × π × (d ｋ / 2) ３ = 1 / 6 × π × d ｋ ３ (nm) Volume of class k in 1 L of micelles: 1000 x V ｋ (mL) For class k of the particle size distribution, the value obtained by dividing the "volume of class k in 1 L of micelles" by the "particle volume per micelle in class k" is defined as the "number of micelles contained in class k per 1 L of micelles." Number of micelles contained in class k per 1 L of micelles: 6 x 10 ２４ ×V ｋ / π×d ｋ ３The "micelle surface area per micelle in class k" is expressed as follows: Micelle surface area per micelle in class k: 4 × π(d ｋ / 2) ２ = πd ｋ ２ Next, the value obtained by multiplying the "micelle surface area per micelle in class k" by the "number of micelles contained in class k per 1 L of micelles" is defined as the "micelle surface area of ​​class k per 1 L of micelles." Micelle surface area of ​​class k per 1 L of micelles: 6 × 10 ２４ ×V ｋ / d ｋ (nm ２ The "volume of all micelles per 1 L of chloroprene polymer latex (including all classes)" is expressed as follows: Volume of all micelles per 1 L of chloroprene polymer latex: 1×ρ ＬＸ / ρ ＣＲ × S = ρ ＬＸ ×S / ρ ＣＲ (L) "The surface area of ​​micelles contained in class k per 1 L of chloroprene polymer latex" is defined as the value obtained by multiplying "the volume of all micelles per 1 L of chloroprene polymer latex" by "the surface area of ​​micelles of class k per 1 L of micelles". Surface area of ​​micelles contained in class k per 1 L of chloroprene polymer latex: 1×ρ ＬＸ xS x 6 x 10 ２４ ×V ｋ / ρ ＣＲ ×d ｋ Further, a numerical value obtained by accumulating "surface area of ​​micelles contained in class k per 1 L of chloroprene polymer latex" for all classes is defined as "surface area of ​​micelles per 1 L of chloroprene polymer latex."

[0035] The numerical value obtained by dividing the "surface area of ​​micelles per 1 L of chloroprene polymer latex" by the "amount n (mol) of emulsifier contained in 1 L of chloroprene polymer latex" is defined as the "surface area of ​​micelles per molecule of emulsifier".

[0036] Specifically, the "micelle surface area per emulsifier molecule" can be calculated by the method described in the Examples.

[0037] According to the present invention, by setting the "micelle surface area per emulsifier molecule" within the above-mentioned range, it is presumed that the dispersibility and stability of the chloroprene polymer latex can be appropriately adjusted, resulting in a chloroprene polymer latex with appropriate mechanical stability. The "micelle surface area per emulsifier molecule" can be controlled by carefully adjusting the production conditions of the chloroprene polymer latex. Specifically, it can be controlled by carefully adjusting the particle size of the monomer droplets in the production conditions of the chloroprene polymer latex, as well as the amount and timing of addition of the emulsifier.

[0038] The chloroprene polymer latex according to one embodiment of the present invention has a "micelle surface area per 1 L of chloroprene polymer latex" calculated by the above formula of 30,000 to 100,000 m ２ The "surface area of ​​micelles per 1 L of chloroprene polymer latex" can be, for example, 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000, or 100,000 m ２ and may be in a range between any two of the values ​​given here.

[0039] The chloroprene polymer latex according to one embodiment of the present invention preferably has a D50 value of 80 to 700 nm, as determined from the particle size distribution. , 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690, 700 nm, and may be within a range between any two of the values ​​exemplified here.

[0040] D50 can be determined from the particle size distribution, specifically by the method described in the Examples. The "surface area of ​​micelles per liter of chloroprene polymer latex," or D50, can be controlled by carefully adjusting the production conditions of the chloroprene polymer latex. Specifically, it can be controlled by carefully adjusting the particle size of the monomer droplets in the production conditions of the chloroprene polymer latex, as well as the amount and timing of addition of the emulsifier.

[0041] The chloroprene polymer latex according to one embodiment of the present invention preferably has a polydispersity index (PI) of 0.01 to 0.30. The polydispersity index may be, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, or 0.30, or may be within a range between any two of the values ​​exemplified herein.

[0042] The polydispersity index is the dispersion (μ ２ ) by the square of the average attenuation rate (Γ), and specifically, it can be determined by the method described in the Examples. The polydispersity index represents the breadth of particle size distribution, and can be controlled by precisely adjusting the production conditions of the chloroprene polymer latex. Specifically, it can be controlled by precisely adjusting the particle size of the monomer droplets in the production conditions of the chloroprene polymer latex, as well as the amount and timing of addition of the emulsifier. When the D50 and / or polydispersity index are within the above-mentioned ranges, the mechanical stability can be improved to a greater extent.

[0043] The chloroprene polymer latex according to one embodiment of the present invention preferably has an aggregate generation rate of 0.1 to 20.0% in a mechanical stability test measured under conditions of a load of 10 kg, a rotation speed of 1000 rpm, and a time period of 10 minutes. The aggregate generation rate is, for example, 0.1, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0, 18.0, 19.0, or 20.0%, and may be within a range between any two of the values ​​exemplified here.

[0044] The aggregate generation rate of the chloroprene polymer latex can be determined by the method described in the Examples. The mechanical stability of the chloroprene polymer latex according to one embodiment of the present invention can be controlled by adjusting the "micelle surface area per emulsifier molecule" through precise adjustment of the production conditions of the chloroprene polymer latex. When the aggregate generation rate of the chloroprene polymer latex according to one embodiment of the present invention is not more than the above upper limit, the chloroprene polymer latex according to one embodiment of the present invention has excellent stability during the production process, storage, and transportation.

[0045] The solid content concentration of the chloroprene polymer latex according to one embodiment of the present invention is, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90% by mass, and may be within a range between any two of the values ​​exemplified here.

[0046] 2. Method for Producing Chloroprene Polymer Latex The method for producing a chloroprene polymer latex according to the present invention is not particularly limited. A method for producing a chloroprene polymer latex according to one embodiment of the present invention may include a monomer droplet micronization step, a polymerization step, and an emulsifier additional addition step. In the monomer droplet micronization step, droplets containing raw monomers, including a chloroprene monomer, are micronized until the average particle size of the droplets is 300 nm or less by colliding the raw monomer droplets with a collision medium in the presence of an initially added emulsifier. In the polymerization step, the raw monomers, including the chloroprene monomer, are polymerized to obtain a chloroprene polymer. In the emulsifier additional addition step, an additional emulsifier is additionally added after the monomer droplet micronization step and after the initiation of polymerization. Here, the amount of the additional emulsifier is more than 60% by mass relative to 100% by mass of the total of the initially added emulsifier and the additional emulsifier. The production method according to one embodiment of the present invention may employ mini-emulsion polymerization.

[0047] <Stock Solution Preparation Step> A method for producing a chloroprene polymer latex according to one embodiment of the present invention may include a stock solution preparation step. The stock solution may contain a chloroprene-containing starting monomer, an emulsifier, and water, and may also contain a chain transfer agent, an initiator, and a hydrophobe. In the stock solution preparation step, the chloroprene-containing starting monomer, an emulsifier, and optionally a molecular weight modifier, an initiator, a hydrophobe, and the like are added to water to prepare the stock solution. Alternatively, in the stock solution preparation step, an emulsifier may be added to water to prepare a soap solution, and the chloroprene-containing starting monomer is added to the molecular weight modifier, a hydrophobe, and optionally an initiator to prepare an oil phase mixture solution, and the soap solution and the oil phase mixture solution are mixed to obtain the stock solution. The initiator may be added during the preparation of the oil phase mixture solution or after the micronization step. When an oil-soluble initiator is used, it is preferably added during the preparation of the oil phase mixture solution, and when a water-soluble initiator is used, it may also be added after the micronization step.

[0048] Examples of the emulsifier include the types of emulsifiers described above. As described below, a production method according to one embodiment of the present invention may include an additional emulsifier addition step. The emulsifier added during preparation of the raw material solution is referred to as an initially added emulsifier, and the emulsifier added in the additional addition step is referred to as an additionally added emulsifier. The amount of the initially added emulsifier added may be 0.5 to 5.0 parts by mass per 100 parts by mass of the raw material monomers including the chloroprene monomer. The amount of the initially added emulsifier added per 100 parts by mass of the raw material monomers including the chloroprene monomer may be, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 parts by mass, and may be within a range between any two of the values ​​exemplified here. The amount of the initially added emulsifier relative to the total of the initially added emulsifier and the additionally added emulsifier (100% by mass) may be less than 40% by mass, for example, 1, 5, 10, 15, 20, 25, 30, 35, or 40% by mass, or may be within a range between any two of the values ​​exemplified here. The total of the initially added emulsifier and the additionally added emulsifier may be the total amount of emulsifiers used in producing the chloroprene polymer latex.

[0049] The molecular weight modifier is not particularly limited, and known molecular weight modifiers commonly used in chloroprene polymerization can be used, such as mercaptan compounds such as dodecyl mercaptan, xanthogen compounds, dithiocarbonate compounds, trithiocarbonate compounds, and carbamate compounds. The amount of molecular weight modifier added per 100 parts by mass of raw material monomers including chloroprene monomer is, for example, 0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 parts by mass, and may be within a range between any two of the values ​​exemplified here.

[0050] The initiator is not particularly limited, and known polymerization initiators commonly used in the polymerization of chloroprene can be used. Examples of the polymerization initiator include potassium persulfate, ammonium persulfate, sodium persulfate, benzoyl peroxide, hydrogen peroxide, water-soluble azo compounds such as 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), oil-soluble azo compounds such as 2,2'-azobisisobutyronitrile, water-soluble organic peroxides such as t-butyl hydroperoxide, and oil-soluble organic peroxides such as 1,1,3,3-tetramethylbutyl-2-ethylhexanoate. The amount of initiator added per 100 parts by mass of raw material monomers including the chloroprene monomer is, for example, 0.01, 0.05, 0.1, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 parts by mass, and may be within a range between any two of the values ​​exemplified here.

[0051] The hydrophobe is not particularly limited, and a compound having low solubility in water can be appropriately used, such as a long-chain alkyl compound such as hexadecane, heptadecane, octadecane, nonadecane, etc. The amount of hydrophobe added relative to 100 parts by mass of the raw material monomers including the chloroprene monomer is, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 parts by mass, and may be within a range between any two of the numerical values ​​exemplified here.

[0052] <Monomer Droplet Micronization Process> In the monomer droplet micronization process, droplets containing raw material monomers, including chloroprene monomers, are micronized until the average particle size of the droplets is 300 nm or less by colliding the raw material monomer droplets with a collision medium in the presence of an initially added emulsifier. Examples of the collision medium include other monomer droplets, raw material solutions such as solvents (water), ceramic balls, etc. Micronization methods can be performed using known devices, such as ultrasonic homogenizers, stirring homogenizers, high-pressure homogenizers, and wet-type micronization devices. One example is the Violamo ultrasonic homogenizer (SONICSTAR 85). When using an ultrasonic homogenizer, it is believed that the raw material solution (including monomer droplets, water, etc.) generated by vacuum collides with the monomer droplets, resulting in micronization of the monomer droplets. For example, the output of the homogenizer may be, for example, 10, 50, 100, 500, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, or 5000 W, or may be within a range between any two of the values ​​exemplified here. Furthermore, the processing time (time for performing the micronization process) of the ultrasonic homogenizer may be, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 60 minutes, or may be within a range between any two of the values ​​exemplified here.

[0053] An example of such a homogenizer is a stirring homogenizer (e.g., AS ONE Corporation, Digital Type AHG-160D). The rotation speed of the stirring homogenizer is, for example, 300, 1000, 5000, 10000, 15000, 20000, 25000, or 30000 rpm, and may be within a range between any two of the values ​​exemplified here.

[0054] Another example is the Starburst series manufactured by Sugino Machine Co., Ltd. In this device, it is believed that the monomer droplets are atomized by collision between ceramic balls or a raw material solution (including monomer droplets, water, etc.). The pressure in the atomization process is, for example, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, or 245 MPa, and may be within a range between any two of the values ​​exemplified here.

[0055] In the monomer droplet micronization step, the monomer droplets are preferably micronized to an average particle size of 300 nm or less. The average particle size of the monomer droplets after the monomer droplet micronization step is, for example, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 300 nm, or may be within a range between any two of the values ​​exemplified here. The average particle size of the monomer droplets can be determined by the method described in the Examples. By micronizing the monomer droplets so that the average particle size falls within the above-mentioned range, a chloroprene polymer latex having more appropriate mechanical stability can be obtained.

[0056] <Polymerization Step> In the polymerization step, raw material monomers including chloroprene monomers are polymerized to obtain a chloroprene-based polymer. The polymerization may at least partially begin when the raw material monomers and the initiator are brought into contact in the raw material solution preparation step. Alternatively, the polymerization step may be initiated by adding an initiator after the monomer droplet microparticulation step, without adding a polymerization initiator in the raw material solution preparation step. In one embodiment of the present invention, after the monomer droplet microparticulation step, the temperature of the microparticulated raw material solution is adjusted and polymerization is carried out for a desired period of time. The polymerization temperature is not particularly limited and may be, for example, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50°C, or may be within a range between any two of the values ​​exemplified herein. The polymerization time is not particularly limited and may be, for example, 0, 10, 20, 30, 40, 50, or 60 hours, or may be within a range between any two of the values ​​exemplified herein.

[0057] The final conversion rate of the raw material monomer is not particularly limited, but may be, for example, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95%, or may be within a range between any two of the values ​​exemplified here. To adjust the final conversion rate, a polymerization terminator may be added to terminate the polymerization reaction when the desired conversion rate is reached.

[0058] The polymerization terminator is not particularly limited, and a known polymerization terminator commonly used in the polymerization of chloroprene can be used. Examples of the polymerization terminator include phenothiazine (thiodiphenylamine), 4-t-butylcatechol, and 2,2-methylenebis-4-methyl-6-t-butylphenol. After the polymerization step is completed, an unreacted monomer removal step can be carried out, in which unreacted monomers remaining after the emulsion polymerization are removed by a conventional method such as reduced pressure distillation.

[0059] <Emulsifier Additional Addition Step> In one embodiment of the present invention, an emulsifier additional addition step can be performed after the monomer droplet micronization step. The emulsifier additional addition step can be performed after the initiation of the polymerization step, after the completion of the polymerization step, or after the unreacted monomer removal step. In one embodiment of the present invention, the raw material solution preparation step, monomer droplet micronization step, polymerization step, unreacted monomer removal step, and emulsifier additional addition step can be performed in this order. In the emulsifier additional addition step, an additional emulsifier is additionally added at least after the monomer droplet micronization step. Here, the amount of additional emulsifier relative to the total of 100% by mass of the initially added emulsifier and the additionally added emulsifier is more than 60% by mass. The amount of additional emulsifier relative to the total of 100% by mass of the initially added emulsifier and the additionally added emulsifier is, for example, 61, 65, 70, 75, 80, 85, 90, 95, or 99% by mass, and may be within a range between any two of the values ​​exemplified here. The amount of the additional emulsifier added may be 0.5 to 5.0 parts by mass relative to 100 parts by mass of the raw material monomers including the chloroprene monomer, and may be, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 parts by mass, or may be within a range between any two of the values ​​exemplified here.

[0060] Furthermore, to the chloroprene polymer latex obtained by the production method according to one embodiment of the present invention, after polymerization, any additive such as a freeze stabilizer, an emulsion stabilizer, a viscosity modifier, an antioxidant, or a preservative may be added, as long as the effects of the present invention are not impaired.

[0061] 3. Adhesive Composition The adhesive composition according to the present invention may contain the above-described chloroprene polymer latex.

[0062] 3.1 pH Adjuster The adhesive composition according to one embodiment of the present invention may contain a pH adjuster. Adding a pH adjuster can further improve the initial adhesive strength and storage stability. A weak acid or a buffer solution can be used as the pH adjuster. Specifically, at least one compound selected from hydroxy acids such as citric acid and glycolic acid, boric acid, amino acids, etc. is desirable, and amino acids are particularly preferred. Examples of amino acids include glycine, alanine, threonine, and proline, with glycine being more preferred in terms of cost, adhesive performance, ease of handling, and the like.

[0063] The adhesive composition according to one embodiment of the present invention preferably contains 1 to 20 parts by mass of a pH adjuster relative to 100 parts by mass of the solid content of the chloroprene polymer latex. The content of the pH adjuster is, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 parts by mass, or may be within a range between any two of the values ​​exemplified here. One type of pH adjuster may be used alone, or two or more types may be used in combination.

[0064] 3.2 Polymer Emulsion The adhesive composition according to one embodiment of the present invention may contain a polymer emulsion (a latex containing a polymer other than a chloroprene-based polymer).

[0065] The polymer emulsion may be one or more selected from acrylic emulsion, urethane emulsion, styrene / butadiene rubber latex, acrylonitrile / butadiene rubber latex, natural rubber latex, etc., and preferably contains an acrylic emulsion. The acrylic emulsion can be obtained by (co)polymerizing a (meth)acrylic acid ester with a monomer that forms a functional group, a monomer that forms a crosslinking group, and / or another copolymerizable monomer, as necessary.

[0066] In the adhesive composition according to one embodiment of the present invention, the content of the polymer emulsion relative to 100 parts by mass of the solids content of the chloroprene polymer latex is, for example, 0, 5, 10, 15, 20, 25, 30, 35, 40, or 45 parts by mass, and may be within a range between any two of the values ​​exemplified here. One type of polymer emulsion may be used alone, or two or more types may be used in combination. By including a polymer emulsion (particularly an acrylic emulsion, which is an acrylic latex containing an acrylic polymer), the adhesive composition according to one embodiment of the present invention can further improve its storage stability and the texture (hardness) of the adhesive layer while maintaining its initial adhesive strength.

[0067] The adhesive composition according to one embodiment of the present invention may contain known components, such as a tackifier, an acid acceptor, an antioxidant, a filler, a pigment, a colorant, a wetting agent, an antifoaming agent, a thickener, etc. Examples of tackifiers include phenolic resins, terpene resins, rosin derivative resins, and petroleum hydrocarbons. In the adhesive composition according to one embodiment of the present invention, the amount of thickener per 100 parts by mass of the solids content of the chloroprene polymer latex may be, for example, 0, 1, 2, 3, 4, or 5 parts by mass, or may be within a range between any two of the values ​​exemplified herein.

[0068] The adhesive composition according to one embodiment of the present invention can be suitably used as an adhesive, preferably an aqueous adhesive, more preferably a one-component aqueous adhesive. The adhesive composition containing the chloroprene polymer latex exhibits excellent spray applicability with little clogging, rapid demulsification after application, and excellent initial adhesive strength. The adhesive composition according to one embodiment of the present invention can be suitably used as a spray-type adhesive, and can be particularly suitably used as a spray-type adhesive for adhering the following adherends:

[0069] Adherends that can be bonded with the adhesive composition according to one embodiment of the present invention include foams made of materials such as polyurethane, ethylene-vinyl acetate copolymer, and polyethylene, as well as wood, cloth, and textiles. The adhesive composition according to one embodiment of the present invention can be used for polyurethane foams, and at least one of the adherends can be polyurethane foam. For example, the adhesive composition is suitable for bonding polyurethane foams to each other, polyurethane foam to wood, and polyurethane foam to cloth, and can be suitably used for bonding, for example, in the manufacture of furniture that includes polyurethane foam components.

[0070] 4. Composition for Forming Dip-Molded Body A composition for forming a dip-molded body according to one embodiment of the present invention contains the chloroprene polymer latex described above. The composition for forming a dip-molded body according to one embodiment of the present invention may contain, in addition to the chloroprene polymer, a metal oxide, an antioxidant, and other necessary chemicals. The composition for forming a dip-molded body according to one embodiment of the present invention may not contain a vulcanizing agent or a vulcanization accelerator, and may not contain sulfur or a vulcanization accelerator such as a thiuram, dithiocarbamate, thiourea, guanidine, xanthogenate, or thiazole.

[0071] 4.1 Metal Oxide The composition for forming an immersion molded body according to one embodiment of the present invention may contain a metal oxide. There are no particular limitations on the metal oxide, and examples include zinc oxide, lead oxide, trilead tetroxide, magnesium oxide, aluminum oxide, iron oxide, beryllium oxide, and titanium oxide. The metal oxide preferably contains zinc oxide. Zinc oxide is generally believed to function as a scavenger for dechlorinated atoms in chloroprene-based polymers. These metal oxides may be used alone or in combination of two or more.

[0072] The amount of metal oxide added is preferably 0.5 to 15.0 parts by mass per 100 parts by mass of the solid content of the chloroprene polymer contained in the composition for forming a dip-molded body. When the amount of metal oxide added is 0.5 parts by mass or more, an improvement in tensile strength at break is expected due to the cross-linking effect between the polymers. When the amount of metal oxide added is 15.0 parts by mass or less, a dip-molded body with excellent flexibility can be obtained. Furthermore, from the viewpoint of the balance of physical properties between the flexibility and tensile strength at break of the obtained dip-molded body, the amount of metal oxide added is more preferably 0.5 to 5.0 parts by mass.

[0073] 4.2 Antioxidant The composition for forming a dip-molded body according to one embodiment of the present invention may also contain an antioxidant. The antioxidant is not particularly limited, and phenolic antioxidants, amine-based antioxidants, heat-resistant oxidation (aging) inhibitors, ozone-resistant antioxidants, etc. can be used. When the obtained dip-molded body is used as a medical glove, a phenolic antioxidant can be used from the viewpoint of the color tone, texture, and hygiene of the dip-molded body. In particular, hindered phenolic antioxidants have a strong effect as described above. Examples of hindered phenol-based antioxidants include 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 2,2'-methylenebis(4-methyl-6-t-butylphenol), 4,4'-butylidene(3-methyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), butylated reaction products of p-cresol and dicyclopentadiene, 2,5'-di-t-butylhydroquinone, and 2,5'-di-t-amylhydroquinone. Among these, butylated reaction products of p-cresol and dicyclopentadiene are desirable from the viewpoint of general dispersibility in aqueous materials. Furthermore, these compounds may be used alone or in combination of two or more.

[0074] The amount of antioxidant added is preferably 0.5 to 10.0 parts by mass per 100 parts by mass of the solid content of the chloroprene polymer contained in the composition for forming a dip-molded body. The amount of antioxidant added may be, for example, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, or 10.0 parts by mass, and may be within a range between any two of the values ​​exemplified here. When the amount of antioxidant added is 0.5 parts by mass or more, the effect of suppressing color change in the dip-molded body can be obtained. When the amount of antioxidant added is 10.0 parts by mass or less, the stability of the composition for forming a dip-molded body can be ensured. Furthermore, from the viewpoint of the balance of physical properties between the flexibility and tensile strength at break of the obtained dip-molded body, the amount of antioxidant added is more preferably 0.5 to 5.0 parts by mass.

[0075] 4.3 Vulcanizing Agent and Vulcanization Accelerator The composition for forming a dip-molded body according to one embodiment of the present invention may also contain a vulcanizing agent and / or a vulcanization accelerator. Furthermore, the composition for forming a dip-molded body according to one embodiment of the present invention does not necessarily contain sulfur or the aforementioned thiuram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthogenate-based, thiazole-based, or other vulcanization accelerators. That is, the composition for forming a dip-molded body includes those containing a vulcanizing agent but not a vulcanization accelerator, those containing a vulcanization accelerator but not a vulcanizing agent, those containing a vulcanization accelerator and a vulcanization accelerator, and those containing neither a vulcanizing agent nor a vulcanization accelerator. Whether or not a vulcanizing agent and a vulcanization accelerator are added can be determined depending on the desired dip-molded body.

[0076] Examples of vulcanizing agents include, but are not limited to, sulfur. The amount of vulcanizing agent added can be 0 to 10.0 parts by mass per 100 parts by mass of the solid content of the chloroprene polymer contained in the composition for forming a dip-molded body. The amount of vulcanizing agent added can be, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 parts by mass, and may be within a range between any two of the values ​​exemplified here.

[0077] A vulcanization accelerator is a chemical added during the vulcanization of raw rubber to act with the vulcanizing agent to increase the vulcanization speed, thereby shortening the vulcanization time, lowering the vulcanization temperature, reducing the amount of vulcanizing agent, and improving the physical properties of the vulcanized rubber. It usually refers to a chemical that accelerates the sulfur vulcanization reaction.

[0078] Examples of vulcanization accelerators include, but are not limited to, thiuram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthogenate-based, thiazole-based, etc. These may be used alone or in combination of two or more types as required.

[0079] Examples of thiuram vulcanization accelerators include tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetrakis(2-ethylhexyl)thiuram disulfide, tetramethylthiuram monosulfide, and dipentamethylenethiuram tetrasulfide.

[0080] Examples of the dithiocarbamate vulcanization accelerator include sodium dibutyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, copper dimethyldithiocarbamate, ferric dimethyldithiocarbamate, and tellurium diethyldithiocarbamate, and zinc dibutyldithiocarbamate is particularly preferred.

[0081] Examples of the thiourea-based vulcanization accelerator include ethylene thiourea, N,N'-diethyl thiourea, trimethyl thiourea, and N,N'-diphenyl thiourea.

[0082] Examples of the guanidine vulcanization accelerator include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, and di-o-tolylguanidine salts of dicatechol borate.

[0083] Examples of xanthogenate-based vulcanization accelerators include zinc butylxanthogenate and zinc isopropylxanthogenate.

[0084] Examples of the thiazole vulcanization accelerator include 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, 2-mercaptobenzothiazole zinc salt, 2-mercaptobenzothiazole cyclohexylamine salt, and 2-(4'-morpholinodithio)benzothiazole.

[0085] The amount of the vulcanization accelerator added may be 0 to 5.0 parts by mass relative to 100 parts by mass of the solid content of the chloroprene polymer contained in the composition for forming a dip-molded body, and may be, for example, 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0, or may be within a range between any two of the values ​​exemplified here.

[0086] 4.4 Method for Producing a Composition for Forming an Immersion Molded Body A method for producing a composition for forming an immersion molded body according to one embodiment of the present invention can include a raw material mixing step of mixing raw materials containing a chloroprene polymer, a metal oxide, an antioxidant, and other required chemicals. In the mixing step, an aqueous dispersion containing the metal oxide, the antioxidant, and other required chemicals can be prepared in advance, and the chloroprene polymer and the aqueous dispersion can be mixed. The mixing step can be carried out using a known mixing device such as a ball mill.

[0087] 5. Dip-molded body (coating / film) An immersion-molded body according to one embodiment of the present invention can be a dip-molded body made from a composition for forming an immersion-molded body, which contains a chloroprene polymer latex. In this specification, the term "immersion-molded body" can refer to a molded body obtained by dip-molding the composition for forming an immersion-molded body, and a molded body obtained by heating the molded body. Furthermore, a product obtained after heating can also be referred to as a dip-molded body.

[0088] A dip-molded product according to one embodiment of the present invention can be obtained by dip-molding a composition for forming a dip-molded product described below by a dip coagulation method, and then heating and drying the resulting film. The dip-molded product according to one embodiment of the present invention can be suitably used as any of industrial gloves, general household gloves, medical gloves, balloons, catheters, and boots.

[0089] The dip-molded product according to the present invention may contain the components contained in the composition for forming a dip-molded product described above. The dip-molded product may contain a chloroprene polymer as a base polymer, and may contain 70% by mass or more of the chloroprene polymer, preferably 80% by mass or more, and more preferably 90% by mass or more, of the dip-molded product taken as 100% by mass. The content of the chloroprene polymer in the dip-molded product taken as 100% by mass may be, for example, 70, 75, 80, 85, 90, 95, 96, 97, 98, 99, or 100% by mass, or may be within a range between any two of the values ​​exemplified here.

[0090] A method for producing a dip-molded product according to one embodiment of the present invention can include a dip-molding step of dip-molding a composition for forming a dip-molded product, which contains a chloroprene polymer obtained by the above-described method for producing a chloroprene polymer, to obtain a dip-molded product.

[0091] Examples of dip molding methods in one embodiment of the present invention include immersion coagulation, simple immersion, thermal immersion, and electrodeposition. The immersion coagulation method can be used because it is easy to manufacture and because it is easy to obtain dip-molded bodies of a uniform thickness. Specifically, a ceramic mold coated with a calcium-based coagulation liquid is immersed in a dip-molded body composition, which is then coagulated. The composition is then leached to remove water-soluble impurities, dried, and heated for vulcanization to form a dip-molded film (rubber film), which is then demolded. This allows for the production of a film-like coating.

[0092] A method for producing a dip-molded product according to one embodiment of the present invention may include a drying step of heating and drying the dip-molded product to obtain a dip-molded product.

[0093] The heating temperature may be set appropriately depending on the composition of the chloroprene polymer, and may be 120 to 180°C. The heating temperature is preferably 120 to 150°C. The heating temperature may be, for example, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, or 220°C, or may be within a range between any two of the values ​​exemplified here. The heating time may be set appropriately depending on the composition of the chloroprene polymer, the shape of the unvulcanized molded body, and the like, and may be 10 to 300 minutes. The heating time may be, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 300 minutes, or may be within a range between any two of the values ​​exemplified here. As an example, a dip-molded product according to one embodiment of the present invention may be one that has been subjected to a heat drying treatment at 130°C for 30 minutes.

[0094] The present invention will be described in more detail below based on examples, but the present invention should not be construed as being limited to these examples.

[0095] Example 1 <Step of Preparing Raw Material Solution> A soap solution was prepared by dissolving 0.433 g of sodium lauryl sulfate (SDS) in 100 g of pure water. 1.25 g of hexadecane, 0.008 g of dodecyl mercaptan, and 0.0748 g of initiator 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) were dissolved in 25 g of chloroprene monomer to prepare an oil phase mixed solution. The soap solution and oil phase mixed solution were transferred to a 500 ml beaker to obtain a raw material solution.

[0096] <Monomer droplet micronization step, polymerization step, and emulsifier addition step> The raw material solution was pre-stirred for 10 minutes with a mechanical stirrer under ice cooling, and then emulsified for 10 minutes using a Violamo ultrasonic homogenizer (SONICSTAR 85) at 100% output (maximum high-frequency output: 85 W, oscillation frequency 21 kHz ± 1 kHz). The average particle size of the droplets containing the chloroprene monomer was 150 nm. The average particle size of the droplets can be measured by diluting the polymerization solution with distilled water to a solids concentration of 0.01% by mass and using an ELSZ Series (manufactured by Otsuka Electronics Co., Ltd.). The average particle size of the polymerization solution can be determined by the cumulant method using the autocorrelation function obtained by photon correlation spectroscopy in dynamic light scattering. The resulting emulsion was transferred to a 500 ml four-neck separable flask and polymerization was carried out at 30°C under stirring with a mechanical stirrer. The temperature of the polymerization liquid was raised to 30° C., and polymerization was carried out for 12 hours. After removing the monomer from the obtained emulsion under reduced pressure, 0.866 g of sodium lauryl sulfate (SDS) was further added to obtain a chloroprene polymer latex.

[0097] (Examples 2 to 4, Comparative Example 1) A chloroprene polymer latex was obtained in the same manner as in Example 1, except that the type of emulsifier, the apparatus used in the monomer droplet micronization step, and the amount of emulsifier added in the emulsifier additional addition step were as shown in Table 1. In Example 3, an agitator homogenizer (AHG-160D, manufactured by AS ONE Co., Ltd.) was used, and in Example 4, a high-pressure homogenizer (Starburst Mini, manufactured by Sugino Machine Co., Ltd.) was used. In Example 2, sodium dodecylbenzenesulfonate (DBS) was used as the emulsifier.

[0098] <Volume-based particle size distribution of micelles> The chloroprene polymer latex was diluted with distilled water to a solids concentration of 0.01% by mass, and the volume-based particle size distribution of the micelles was measured in the range of 1 nm to 10,000 nm using an ELSZ Series (manufactured by Otsuka Electronics Co., Ltd.) to obtain a histogram. The histogram has 45 classes obtained by dividing the range of 1 nm to 10,000 nm into 45 equal parts on the horizontal axis, and the vertical axis represents the volume distribution.

[0099] Using the particle size class values ​​of each class of the histogram and the volume distribution of each class, the micelle surface area per molecule of the emulsifier was calculated according to the following formula:

[0100] In the above formula, d ｋ represents the class value (nm) of the particle diameter of the class k where the particle diameter is the kth smallest, and the class value is the median value of the class. For example, if the range of class k is "X ｋ That's all, Y ｋ If "less than" then d ｋ is X ｋ and Y ｋ is the average value of V ｋ is the volume distribution of class k, and the sediment distribution of class k having the kth smallest particle diameter, i.e., the value on the vertical axis, is used. The total of the volume distributions of all classes is 1, and the volume distribution of each class k is expressed as a numerical value between 0 and 1. S is the solid content ratio of the chloroprene polymer latex. S is the ratio of the solid content of the chloroprene polymer latex to the chloroprene polymer latex, and is expressed as a numerical value between 0 and 1. ρ Ｌｘ is the specific gravity (g / cm) of the chloroprene polymer latex ３ ) and was calculated from the mass per unit volume of the chloroprene polymer latex measured at 25°C. ＣＲ is the specific gravity (g / cm) of the chloroprene polymer at 25°C ３ ) and 1.21 g / cm ３ n is the amount (mol) of emulsifier contained in 1 L of chloroprene polymer latex. Ａ Avogadro's number is 6.02 x 10 ２３ mol －１ It was decided.

[0101] The average particle diameter (D50, cumulative 50% diameter) was calculated from the particle size distribution. The dispersion (μ ２ The polydispersity index (PI) was calculated by dividing the average decay rate (Γ) by the square of the average decay rate (Γ).

[0102] <Mechanical Stability> Using a Marlon testing apparatus, a shear force of 10 kg load and 1,000 rpm was applied to 50 g of a chloroprene polymer latex adjusted to a solids concentration of 60% by mass for 10 minutes, and the amount of aggregates generated was evaluated. After applying the shear force under the above conditions, the aggregates attached to the rotor of the Marlon testing apparatus were collected on a SUS80 mesh wire screen, washed with pure water, dried under reduced pressure, and then their mass was measured. The aggregate generation rate was calculated from the measured dry mass of the aggregates using the following formula to serve as an index of mechanical stability. A smaller value of the aggregate generation rate indicates better stability against shear forces and better mechanical stability. Aggregate generation rate (mechanical stability) (mass %) = dry mass of aggregates [g] / solid mass of chloroprene polymer latex [g] × 100

[0103] The rate of occurrence of aggregates (mechanical stability) was evaluated according to the following criteria: ○: 20% or less ×: more than 20%

[0104]

Claims

1. A chloroprene polymer latex containing micelles containing a chloroprene polymer and an emulsifier, wherein the volume-based particle size distribution of the micelles is measured by dynamic light scattering in the range of 1 nm to 10,000 nm to obtain a histogram, the horizontal axis of the histogram representing particle diameters expressed in common logarithms, the horizontal axis having 45 classes obtained by dividing the range of 1 nm to 10,000 nm into 45 equal classes, and the vertical axis representing volume distribution, and the class value of the particle diameter of the class k having the kth smallest particle diameter is represented by d ｋ nm The volume distribution of class k is V ｋ , the solid content of the chloroprene polymer latex is S, and the specific gravity of the chloroprene polymer latex is ρ Ｌｘ g / cm ３ , the specific gravity of the chloroprene polymer is ρ ＣＲ g / cm ３ The amount of emulsifier contained in 1 L of the chloroprene polymer latex is n mol, Avogadro's number is N Ａ A chloroprene polymer latex which satisfies the following formula when 2. The chloroprene polymer latex according to claim 1, wherein D50 obtained from the particle size distribution is 80 to 700 nm.

3. The chloroprene polymer latex according to claim 1 or 2, wherein the content of the emulsifier per 100 parts by mass of the chloroprene polymer is 0.5 to 10.0 parts by mass.

4. The chloroprene polymer latex according to claim 1 or 2, wherein the mechanical stability measured for 10 minutes under conditions of a load of 10.0 kg and a rotation speed of 1,000 rpm is 0.1 to 20.0%.

5. The chloroprene polymer latex according to claim 1 or 2, wherein the micelle surface area per 1 L of the chloroprene polymer latex is 30,000 to 100,000 m ２ A chloroprene polymer latex.

6. An adhesive composition comprising the chloroprene polymer latex according to claim 1 or 2.

7. A composition for forming a dip-molded body, comprising the chloroprene polymer latex according to claim 1 or 2.

8. A dip-molded body made from the composition for forming a dip-molded body according to claim 7.

9. A method for producing a chloroprene polymer latex containing micelles containing a chloroprene polymer and an emulsifier, the method comprising: a monomer droplet micronization step, a polymerization step, and an emulsifier additional addition step; in the monomer droplet micronization step, droplets containing a raw material monomer including a chloroprene monomer are micronized in the presence of an initially added emulsifier by causing the raw material monomer droplets to collide with a collision medium to micronize the droplets until the average particle size of the droplets is 300 nm or less; in the polymerization step, the raw material monomer including the chloroprene monomer is polymerized to obtain a chloroprene polymer; and in the emulsifier additional addition step, an additionally added emulsifier is additionally added after the monomer droplet micronization step, and the amount of the additionally added emulsifier is more than 60% by mass relative to 100% by mass of the total of the initially added emulsifier and the additionally added emulsifier.

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