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

To provide a chloroprene-based polymer latex having adequate mechanical stability.SOLUTION: 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. Formula 1.SELECTED DRAWING: None

Description

[Technical Field]

[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. [Background technology]

[0002] Chloroprene rubber has excellent mechanical properties and is resistant to ozone and chemicals. These properties are utilized in a wide range of fields, including automotive parts, adhesives, and various industrial rubber parts. 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). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2011 / 004860 Summary of the Invention [Problem to be solved by the invention]

[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. [Means for solving the problem]

[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 the 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 expressed as n mol, and Avogadro's number is expressed as N A When the above formula is satisfied, a chloroprene polymer latex is provided which satisfies the following formula:

[0007]

number

[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 described below as examples, and 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 in the range of 1 nm to 10,000 nm by dynamic light scattering to obtain a histogram, the abscissa of the histogram representing particle diameters expressed in common logarithms, the abscissa of the histogram having 45 classes obtained by dividing the range of 1 nm to 10,000 nm into 45 equal classes, the ordinate of the histogram 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 the 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

number

[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. DETAILED DESCRIPTION OF THE INVENTION

[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 contains micelles each 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 a value obtained from a particle size distribution obtained under specific conditions, within a specific range.

[0013] 1.1 Chloroprene polymers The chloroprene 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 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 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 contain monomer units derived from a monomer other than the chloroprene monomer. The monomer other than the chloroprene monomer is not particularly limited as long as it is copolymerizable with the chloroprene monomer, and examples thereof include (meth)acrylic acid esters (e.g., methyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate), hydroxyalkyl (meth)acrylates (e.g., 2-hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate), unsaturated nitriles (e.g., acrylonitrile, methacrylonitrile, ethacrylonitrile, phenylacrylonitrile), 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, ethylene, styrene, and sulfur.

[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, such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene (excluding chloroprene).

[0017] A chloroprene-based polymer according to one embodiment of the present invention may contain chloroprene monomer units and 2,3-dichloro-1,3-butadiene monomer units. A 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 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 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 polymer according to one embodiment of the present invention may contain an 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 nitrogen atom content in the chloroprene polymer. Specifically, the nitrogen atom content 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. Oxygen is used as the combustion gas at a flow rate of 0.2 mL / min, and helium is used as the carrier gas at a flow rate of 80 mL / min. 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 one embodiment of the present invention may contain 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 contains 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 the total of all 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 3g / mol and may be within a 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 × 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 within a 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 a 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 Emulsifiers The chloroprene polymer latex according to the present invention contains an emulsifier. The emulsifier is not particularly limited, and any known emulsifier 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 ester salts such as sodium lauryl sulfate; alkyl benzene sulfonate salts 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 sulfates, alkyl benzene sulfonates, and resin salts, and more preferably contains at least one of alkyl sulfates and alkyl benzene sulfonates. The number of carbon atoms in the alkyl sulfates and alkyl benzene sulfonates 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 the emulsifier can be adjusted.

[0030] 1.3 Characteristics of chloroprene polymer latex The chloroprene polymer latex according to the present invention contains 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 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, with an apparatus capable of measurement by dynamic light scattering (for example, ELSZ Series (manufactured by Otsuka Electronics Co., Ltd.)). The histogram has 45 classes, with the horizontal axis representing particle diameter (nm) expressed in common logarithm and the range of 1 nm to 10,000 nm being divided into 45 equal parts, and the vertical axis representing 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 size class values ​​of each class of the histogram and the volume distribution of each class, the micelle surface area per emulsifier molecule is 0.10 to 0.40 (nm 2 / 1 molecule of emulsifier).

number

[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 kth smallest particle size class k. Here, the class value can be the median value of each class. For example, if the range of class k is "X kThat's all, Y k If "less than" then d k is X k and Y k It can be taken as the average value of V k is the volume distribution of class k, and the volume distribution of class k with the kth smallest particle diameter, i.e., the value on the vertical axis, can be used. Note that 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 solid content ratio 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 calculated from the mass per unit volume of the chloroprene polymer latex measured at 25°C. ρ 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 This can be done. n is the amount (mol) of emulsifier contained in 1 L of chloroprene polymer latex. N A Avogadro's number is 6.02 × 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 in class k per 1 L of micelles: 6 x 10 24 ×V k / π×d k 3 Furthermore, the "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 x 10 24 ×V k / d k (nm 2 ) The "volume of all micelles (including all classes) per liter of chloroprene polymer latex" is expressed as follows: Total micelle volume per liter 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 "volume of all micelles per 1 L of chloroprene polymer latex" multiplied by the "surface area of ​​micelles of class k per 1 L of micelles". Surface area of ​​micelles contained in class k per liter of chloroprene polymer latex: 1×ρ LX ×S×6×10 24 ×V k / ρCR ×d k Further, the value obtained by accumulating the "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]

number

number

[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, it is presumed that by adjusting the "micelle surface area per emulsifier molecule" within the above-mentioned range, the dispersibility and stability of the chloroprene polymer latex can be appropriately adjusted, and the chloroprene polymer latex has appropriate mechanical stability. The "micelle surface area per emulsifier molecule" can be controlled by precisely adjusting the production conditions of the chloroprene polymer latex, specifically, by precisely adjusting the particle size of the monomer droplets in the production conditions of the chloroprene polymer latex, and 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 2The "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, 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 of 80 to 700 nm, as determined from the particle size distribution. The D50 may be, for example, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420 , 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 herein.

[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 is, 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 here.

[0042] The polydispersity index is the dispersion (μ 2 The polydispersity index can be determined by dividing the average particle size distribution (Γ) by the square of the average attenuation rate (Γ), and specifically, can be determined by the method described in the Examples. The polydispersity index indicates the breadth of the particle size distribution, and can be controlled by carefully adjusting the production conditions of the chloroprene polymer latex. Specifically, the polydispersity index 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. When the D50 and / or polydispersity index is within the above range, 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 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 rate of occurrence of aggregates in 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 chloroprene polymer latex according to one embodiment of the present invention has an aggregate generation rate not higher than the above upper limit, it 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 the chloroprene polymer latex according to the present invention is not particularly limited. A method for producing a chloroprene polymer latex according to an 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 process, droplets containing raw material monomers including chloroprene monomers are collided with a collision medium in the presence of an initially added emulsifier, thereby micronizing the droplets until their average particle size becomes 300 nm or less. In the polymerization step, raw material monomers including the chloroprene monomer are polymerized to obtain a chloroprene polymer. In the additional emulsifier addition step, the additional emulsifier is added after the monomer droplet micronization step and after the initiation of polymerization, where 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 additionally added emulsifier. A manufacturing method according to one embodiment of the present invention can employ mini-emulsion polymerization.

[0047] <Raw material solution preparation process> A method for producing a chloroprene polymer latex according to one embodiment of the present invention may include a raw material solution preparation step. The raw material solution may contain raw material monomers containing chloroprene, an emulsifier, and water, and may also contain a chain transfer agent, an initiator, and a hydrophobe. In the raw material solution preparation step, the raw material solution may be prepared by adding the raw material monomers containing chloroprene, an emulsifier, and, if necessary, a molecular weight modifier, an initiator, a hydrophobe, etc. to water. Alternatively, in the raw material solution preparation step, an emulsifier may be added to water to prepare a soap solution, and the raw material monomers containing chloroprene may be added with the molecular weight modifier, the hydrophobe, and, if necessary, an initiator to prepare an oil phase mixture solution, and the soap solution and the oil phase mixture solution may be mixed to obtain the raw material 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 refers to 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 chloroprene polymerization can be used. Examples of polymerization initiators 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 any compound having low solubility in water can be used as appropriate, including long-chain alkyl compounds such as hexadecane, heptadecane, octadecane, and nonadecane. The amount of hydrophobe added per 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 values ​​exemplified here.

[0052] <Monomer droplet micronization process> In the monomer droplet micronization process, droplets containing raw material monomers including chloroprene monomers are collided with a collision medium in the presence of an initially added emulsifier, thereby micronizing the droplets until their average particle size becomes 300 nm or less. Examples of the medium to be impacted include other monomer droplets, raw material solutions such as solvents (water), ceramic balls, and the like. Examples of the micronization method include known devices such as ultrasonic homogenizers, stirring homogenizers, high-pressure homogenizers, and wet-type micronization devices. One example is the Violamo ultrasonic homogenizer (SONICSTAR85). When an ultrasonic homogenizer is used, the raw material solution (containing monomer droplets, water, etc.) generated by the vacuum collides with the monomer droplets, which is thought to micronize 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 of the ultrasonic homogenizer (the time for performing the micronization process) 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 is an agitation homogenizer (e.g., AS ONE Corporation, Digital Type AHG-160D). The rotation speed of the agitation 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 with more appropriate mechanical stability can be obtained.

[0056] <Polymerization process> In the polymerization step, raw material monomers including a chloroprene monomer are polymerized to obtain a chloroprene-based polymer. The polymerization may at least partially start when the raw material monomer and the initiator come into contact with each other in the raw material solution preparation step. Alternatively, the polymerization may be started by adding the initiator after the monomer droplet microparticulation step without adding the polymerization initiator in the raw material solution preparation step. In one embodiment of the present invention, after the monomer droplet micronization step, the temperature of the micronized 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 here. 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 here.

[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 any known polymerization terminator commonly used in the polymerization of chloroprene can be used, such as 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 vacuum distillation.

[0059] <Emulsifier addition process> In one embodiment of the present invention, the additional emulsifier addition step can be carried out after the monomer droplet micronization step. The additional emulsifier addition step can be carried out after the start of the polymerization step, after the end of the polymerization step, or after the unreacted monomer removal step. In one embodiment of the present invention, the raw material solution preparation step, the monomer droplet micronization step, the polymerization step, the unreacted monomer removal step, and the additional emulsifier addition step can be carried out 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 the additional emulsifier relative to 100% by mass of the initial emulsifier and the additional emulsifier is more than 60% by mass. The amount of the additional emulsifier relative to 100% by mass of the initial emulsifier and the additional emulsifier may be, for example, 61, 65, 70, 75, 80, 85, 90, 95, or 99% by mass, or may be within a range between any two of the values ​​exemplified here. The amount of the additional emulsifier added can 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 can contain the above-mentioned chloroprene polymer latex.

[0062] 3.1 pH adjuster The adhesive composition according to one embodiment of the present invention may contain a pH adjuster. Addition of a pH adjuster can further improve 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, and amino acids is preferred, with amino acids being 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 pH adjuster may be used alone, or two or more pH adjusters 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 needed.

[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 used effectively in bonding, for example, in the manufacture of furniture containing polyurethane foam components.

[0070] 4. Composition for forming immersion molded bodies 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 oxides The composition for forming a dip molded body according to one embodiment of the present invention may contain a metal oxide. The metal oxide is not particularly limited, and examples thereof 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, the cross-linking effect between the polymers is expected to improve the tensile strength at break. 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 Antioxidants 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 examples thereof include phenolic antioxidants, amine-based antioxidants, heat-resistant oxidation (aging) inhibitors, and ozone-resistant antioxidants. When the resulting dip-molded body is used as a medical glove, a phenolic antioxidant can be used from the viewpoints of the color tone, texture, and hygiene of the dip-molded body. In particular, hindered phenolic antioxidants have a strong effect. 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 generally preferred because they are dispersible in aqueous materials. These compounds may be used alone or in combination.

[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, or 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 agents and vulcanization accelerators 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 may not contain sulfur or the aforementioned vulcanization accelerators such as thiuram-based, dithiocarbamate-based, thiourea-based, guanidine-based, xanthogenate-based, and thiazole-based 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 vulcanizing agent but not a vulcanization accelerator, those containing a vulcanizing agent 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 dip-molded body to be produced.

[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 dip-molded bodies. 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 dithiocarbamate vulcanization accelerators include sodium dibutyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, copper dimethyldithiocarbamate, ferric dimethyldithiocarbamate, and tellurium diethyldithiocarbamate, with zinc dibutyldithiocarbamate being 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, cyclohexylamine salt of 2-mercaptobenzothiazole, and 2-(4'-morpholinodithio)benzothiazole.

[0085] The amount of the vulcanization accelerator added can 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 a dip-molded body A method for producing a composition for forming a dip-molded body according to one embodiment of the present invention can include a raw material mixing step of mixing raw materials including a chloroprene-based 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 necessary chemicals may be prepared in advance, and the chloroprene polymer and the aqueous dispersion may be mixed together. The mixing step can be carried out using a known mixing device such as a ball mill.

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

[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 above-described composition for forming a dip-molded product. The dip-molded product may contain a chloroprene polymer as a base polymer, and may contain 70% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more of the chloroprene polymer, based on 100% by mass of the dip-molded product. The content of the chloroprene polymer in the dip-molded product based on 100% by mass of the dip-molded product 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 the immersion coagulation method, simple immersion method, thermal immersion method, and electrodeposition method. The immersion coagulation method can be used from the viewpoints of ease of production and the ease of obtaining dip-molded bodies of a uniform thickness. Specifically, a ceramic mold coated with a calcium-based coagulation liquid is immersed in a composition for forming a dip-molded body, and the composition for forming a dip-molded body is coagulated. After removing water-soluble impurities by leaching, the composition is dried, and then heated and vulcanized to form a dip-molded film (rubber film), which is then released from the mold. 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 subjected to a heat drying treatment at 130°C for 30 minutes. [Example]

[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 <Raw material solution preparation process> A soap solution was prepared by dissolving 0.433 g of sodium lauryl sulfate (SDS) in 100 g of pure water. 25 g of chloroprene monomer was dissolved with 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) to prepare an oil phase mixed solution. The soap solution and oil phase mixed solution were transferred to a 500 ml beaker to obtain the raw material solution.

[0096] <Monomer droplet micronization step, polymerization step, and emulsifier additional addition step> The raw material solution was pre-stirred with a mechanical stirrer under ice cooling for 10 minutes, and then emulsified using a Violamo ultrasonic homogenizer (SONICSTAR85) at 100% output (maximum high-frequency output: 85 W, oscillation frequency: 21 kHz ± 1 kHz) for 10 minutes, resulting in droplets containing chloroprene monomer with an average particle size of 150 nm. The average droplet size can be measured using an ELSZ Series (manufactured by Otsuka Electronics Co., Ltd.) after diluting the polymerization solution with distilled water to a solids concentration of 0.01% by mass. 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 polymerized at 30°C while stirring with a mechanical stirrer. The polymerization was continued for 12 hours at a temperature of 30°C. The monomer was removed from the resulting emulsion under reduced pressure, and then 0.866 g of sodium lauryl sulfate (SDS) was 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 agitation homogenizer (AHG-160D, manufactured by AS ONE) 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, with the horizontal axis representing particle diameter expressed in common logarithm and the horizontal axis dividing the range of 1 nm to 10,000 nm into 45 equal parts, and the vertical axis representing volume distribution.

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

number

[0100] In the above formula, d k represents the particle size class value (nm) of the kth smallest particle size class k, and the class value is the center 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 kis the volume distribution of class k, and the sediment distribution of class k with the kth smallest particle diameter, i.e., the value on the vertical axis, is used. Note that the sum of the volume distributions of all classes is 1, and the volume distribution of each class k is expressed as a number 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 value between 0 and 1 for the latex. 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. ρ CR is the specific gravity (g / cm) of the chloroprene polymer at 25°C 3 ) and 1.21 g / cm 3 It was decided. n is the amount (mol) of emulsifier contained in 1 L of chloroprene polymer latex. N A Avogadro's number is 6.02 × 10 23 mol -1 It was decided.

[0101] Furthermore, the average particle size (D50, cumulative 50% diameter) was determined from the particle size distribution. In addition, based on the results of cumulant analysis of the autocorrelation function obtained by the photon correlation method, the variance (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, 50 g of chloroprene polymer latex adjusted to a solids concentration of 60% by mass was subjected to a shear force of 10 kg under a load of 1000 rpm for 10 minutes, and the amount of aggregates generated was evaluated. After applying the shear force under the above conditions, the aggregates adhering 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 as an index of mechanical stability. A smaller aggregate generation rate indicates better stability against shear force 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 agglomeration (mechanical stability) was evaluated according to the following criteria. ○: 20% or less ×: More than 20%

[0104] [Table 1]

Claims

1. A chloroprene polymer latex containing micelles containing a chloroprene polymer and an emulsifier, 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, and a histogram is obtained. The histogram has a horizontal axis representing particle diameters expressed in common logarithms, a range of 1 nm to 10,000 nm, and 45 classes obtained by equally dividing the horizontal axis into 45 classes, and a vertical axis representing volume distribution, The particle size class value of the particle size class k having the kth smallest particle size is d ｋ nm The volume distribution of class k is V ｋ , The solid content of the chloroprene polymer latex is S, 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 In this case, A chloroprene polymer latex that satisfies the following formula: [Equation 1]

2. 2. The chloroprene polymer latex according to claim 1, wherein D50 obtained from the particle size distribution is 80 to 700 nm.

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

4. 3. The chloroprene polymer latex according to claim 1, wherein a 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. 3. The chloroprene polymer latex according to claim 1, 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, comprising: The production method includes 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 caused to collide with a collision medium in the presence of an initially added emulsifier, thereby micronizing the droplets until the average particle diameter of the droplets is 300 nm or less; In the polymerization step, raw material monomers including the chloroprene monomer are polymerized to obtain a chloroprene-based polymer, In the emulsifier additional addition step, an additional emulsifier is additionally added after the monomer droplet micronization step, The production method, wherein 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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