Chloroprene-based polymer latex composition and adhesive composition

Abstract

Provided are: a chloroprene-based polymer latex composition with which it is possible to obtain an adhesive composition having an excellent initial adhesive strength; and an adhesive composition containing the chloroprene-based polymer latex composition.　According to the present invention, there is provided a chloroprene-based polymer latex composition containing a chloroprene-based polymer and a C7-10 aromatic compound, wherein the total content of the C7-10 aromatic compound in the chloroprene-based polymer latex composition is 0.0001-0.0100 parts by mass per 100 parts by mass of a solid content in the chloroprene-based polymer latex composition.

Description

Chloroprene polymer latex composition and adhesive composition

[0001] The present invention relates to a chloroprene polymer latex composition and an adhesive composition.

[0002] Chloroprene polymer latex compositions containing a chloroprene polymer are used in various fields, such as civil engineering and construction, water-based adhesives for plywood, furniture, shoes, wetsuits, etc., dip-molded products such as work gloves, laboratory gloves, medical gloves, balloons, etc., and waterproof coating films for civil engineering and construction, etc.

[0003] For example, Patent Document 1 discloses a chloroprene polymer latex containing an emulsifier which is an alkali metal salt of a carboxylic acid and 0.1 to 0.5 parts by weight of a polyoxyalkylene derivative represented by a specific formula per 100 parts by weight of the chloroprene polymer latex, and an adhesive composition containing the chloroprene polymer latex.

[0004] JP 2016-160295 A

[0005] However, adhesive compositions containing conventional chloroprene polymer latex compositions sometimes have insufficient initial adhesive strength. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a chloroprene polymer latex composition that can provide an adhesive composition having excellent initial adhesive strength, and an adhesive composition containing the same.

[0006] According to the present invention, there is provided a chloroprene polymer latex composition comprising a chloroprene polymer and an aromatic compound having 7 to 10 carbon atoms, wherein the total content of the aromatic compound having 7 to 10 carbon atoms in the chloroprene polymer latex composition is 0.0001 to 0.0100 parts by mass per 100 parts by mass of solids in the chloroprene polymer latex composition.

[0007] As a result of extensive investigations, the present inventors have found that by highly precisely adjusting the amount of the aromatic compound having 7 to 10 carbon atoms in a chloroprene polymer latex composition, a chloroprene polymer latex composition can be obtained that can provide an adhesive composition having excellent initial adhesive strength, and have thus completed the present invention.

[0008] Various embodiments of the present invention are exemplified below. The embodiments shown below can be combined with each other. [1] A chloroprene polymer latex composition containing a chloroprene polymer and an aromatic compound having 7 to 10 carbon atoms, wherein the total content of the aromatic compound having 7 to 10 carbon atoms is 0.0001 to 0.0100 parts by mass per 100 parts by mass of the solid content of the chloroprene polymer latex composition. [2] The chloroprene polymer latex composition according to [1], wherein the aromatic compound having 7 to 10 carbon atoms comprises at least one selected from the group consisting of toluene, ethylbenzene, xylene, and styrene. [3] An adhesive composition comprising the chloroprene polymer latex composition according to [1] or [2].

[0009] The chloroprene polymer latex composition of the present invention can provide an adhesive composition having excellent initial adhesive strength. The adhesive composition containing the chloroprene polymer latex composition of the present invention can be suitably used as a spray-type adhesive for bonding, for example, polyolefin resins and foams, such as polyurethane foams.

[0010] 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.

[0011] 1. Chloroprene Polymer Latex Composition The chloroprene polymer latex composition according to the present invention comprises a chloroprene polymer and an aromatic compound having 7 to 10 carbon atoms, wherein the total content of the aromatic compound having 7 to 10 carbon atoms is 0.0001 to 0.0100 parts by mass per 100 parts by mass of the solid content in the chloroprene polymer latex composition.

[0012] 1.1 Chloroprene Polymer In the present invention, chloroprene polymer latex refers to a latex containing a chloroprene polymer. Furthermore, chloroprene polymer refers to a polymer containing monomer units derived from 2-chloro-1,3-butadiene (hereinafter also referred to as chloroprene monomer), and includes homopolymers of chloroprene monomers and copolymers containing monomer units derived from chloroprene monomers and other monomers copolymerizable with chloroprene monomers. Examples of other monomers include 1-chloro-1,3-butadiene, 2,3-dichloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, acrylic acid and its esters, and methacrylic acid and its esters.

[0013] The chloroprene polymer latex composition according to one embodiment of the present invention preferably contains 60 to 100% by mass of chloroprene monomer units, based on 100% by mass of the chloroprene polymer contained in the chloroprene polymer latex composition. The content of the chloroprene monomer units may be, for example, 60, 65, 70, 75, 80, 85, 90, 95, 99, or 100% by mass, or may be within a range between any two of the values ​​exemplified here.

[0014] The chloroprene polymer latex composition according to one embodiment of the present invention may contain one type of chloroprene polymer, or may contain two or more types of chloroprene polymers. The chloroprene polymer latex composition according to one embodiment of the present invention preferably contains a homopolymer of a chloroprene monomer. The chloroprene polymer latex composition according to one embodiment of the present invention preferably contains 60 to 100% by mass of the homopolymer of a chloroprene monomer, based on 100% by mass of the solids content of the chloroprene polymer latex contained in the chloroprene polymer latex composition. The content of the homopolymer of a chloroprene monomer may be, for example, 60, 65, 70, 75, 80, 85, 90, 95, or 100% by mass, or may be within a range between any two of the values ​​exemplified here. By including the homopolymer of a chloroprene monomer in the chloroprene polymer latex composition according to one embodiment of the present invention, the contact property, heat-resistant adhesion, and initial bond strength of an adhesive composition containing the chloroprene polymer latex composition can be further improved.

[0015] <Toluene-insoluble content> The chloroprene polymer according to one embodiment of the present invention preferably has a toluene-insoluble content of 30% by mass or less, more preferably 10% by mass or less. The toluene-insoluble content is, 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, and may be within a range between any two of the values ​​exemplified here. In the present invention, the toluene-insoluble content refers to the content of gel content in the chloroprene polymer that is insoluble in toluene. Furthermore, the sol refers to a component that is soluble in toluene. When the toluene-insoluble matter (gel matter) of the chloroprene polymer according to one embodiment of the present invention is within the above-mentioned range, it is presumed that the chloroprene polymer contains an appropriate amount of sol having excellent molecular mobility, and fusion of the molecular chains of the chloroprene polymer at the adhesive interface occurs quickly, adhesive strength is instantaneously developed, and superior initial adhesive strength can be developed.

[0016] The toluene-insoluble content can be calculated by the following formula, specifically, by the method described in the Examples: Toluene-insoluble content (gel content) = B / A × 100 (%), where Ag is the mass of the chloroprene polymer obtained by freeze-drying the chloroprene polymer latex or the chloroprene polymer latex composition, and B is the gel content (insoluble content) separated from a mixture obtained by dissolving the freeze-dried latex in toluene.

[0017] The toluene-insoluble content can be controlled by adjusting the polymerization conditions during polymerization of the chloroprene polymer, for example, the types and amounts of the polymerization initiator and chain transfer agent, as well as production conditions such as the polymerization temperature, polymerization time, and polymerization rate.

[0018] When the chloroprene polymer latex composition contains two or more chloroprene polymers, the toluene-insoluble content of the mixture of the two or more chloroprene polymers is preferably within the above-mentioned range.

[0019] 1.2 Aromatic Compound Having 7 to 10 Carbon Atoms The chloroprene polymer latex composition according to the present invention contains an aromatic compound having 7 to 10 carbon atoms. Examples of the aromatic compound having 7 to 10 carbon atoms include toluene, o-xylene, m-xylene, p-xylene, styrene, ethylbenzene, 2-ethyltoluene, 3-ethyltoluene, 4-ethyltoluene, cumene, 2-propyltoluene, 3-propyltoluene, 4-propyltoluene, 1,2-diethylbenzene, 1,3-diethylbenzene, and 1,4-diethylbenzene. The aromatic compound having 7 to 10 carbon atoms may include an aromatic compound in which one or more hydrogen atoms of the above-mentioned aromatic compounds have been substituted with a hydroxyl group, an amino group, a nitro group, a carbonyl group, a carboxyl group, an isocyanate group, or the like. The aromatic compound having 7 to 10 carbon atoms may also include an aromatic compound in which one or more hydrogen atoms of the above-mentioned aromatic compounds have been substituted with a halogen (chlorine atom, bromine atom, iodine atom, or fluorine atom). The aromatic compound having 7 to 10 carbon atoms may be an aromatic compound substituted with a substituent containing a carbon atom, such as salicylic acid or acetophenone, and may also include a compound having 6 carbon atoms before the substitution. The aromatic compound having 7 to 10 carbon atoms according to the present invention may include at least one selected from the group consisting of toluene, xylene, styrene, ethylbenzene, and aromatic compounds in which one of the hydrogen atoms of these compounds has been substituted, and may include at least one selected from the group consisting of toluene, xylene, styrene, and ethylbenzene.

[0020] The aromatic compound having 7 to 10 carbon atoms according to one embodiment of the present invention may have, for example, 7, 8, 9, or 10 carbon atoms, or may be within a range between any two of the numerical values ​​exemplified herein. The aromatic compound having 7 to 10 carbon atoms according to one embodiment of the present invention may have a molecular weight of 80 to 120. The aromatic compound having 7 to 10 carbon atoms according to one embodiment of the present invention may have, for example, 80, 85, 90, 95, 100, 105, 110, 115, or 120 carbon atoms, or may be within a range between any two of the numerical values ​​exemplified herein.

[0021] In the chloroprene polymer latex composition according to the present invention, the total content of the aromatic compounds having 7 to 10 carbon atoms is 0.0001 to 0.0100 parts by mass, and preferably 0.0002 to 0.0091 parts by mass, relative to 100 parts by mass of the solid content in the chloroprene polymer latex composition. The total content of the aromatic compounds having 7 to 10 carbon atoms relative to 100 parts by mass of the solid content in the chloroprene polymer latex composition is, for example, 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.0010, 0.0015, 0.0020, 0.0025, 0.0030, 0.0035, 0.0040, 0.0045, 0.0050, 0.0055, 0.0060, 0.0065, 0.0070, 0.0075, 0.0080, 0.0085, 0.0090, 0.0095, or 0.0100 parts by mass, and may be within a range between any two of the numerical values ​​exemplified here.

[0022] The chloroprene polymer latex composition according to the present invention has a highly precise adjustment of the total content of aromatic compounds having 7 to 10 carbon atoms per 100 parts by mass of solids in the chloroprene polymer latex composition. This presumably results in an appropriate adjustment of the surface tension of the chloroprene polymer latex composition, thereby adjusting the wettability of an adhesive composition containing the chloroprene polymer latex composition to an adherend, and thereby achieving excellent initial adhesive strength. More specifically, the chloroprene polymer latex composition according to the present invention has a total content of aromatic compounds having 7 to 10 carbon atoms per 100 parts by mass of solids in the chloroprene polymer latex composition that is equal to or greater than the above-mentioned lower limit, thereby presumably improving the wettability and plasticity of the adhesive composition to an adherend. The wettability can be improved as the difference between the surface tension of the adherend and the surface tension of the liquid increases. The adhesive composition containing the chloroprene polymer latex composition according to the present invention has improved wettability, particularly to adherends containing polyurethane or polyolefin resins, and is particularly improved when the adherend contains polyurethane. Furthermore, in the chloroprene polymer latex composition according to the present invention, the total content of the aromatic compounds having 7 to 10 carbon atoms per 100 parts by mass of the solid content in the chloroprene polymer latex composition is the above-mentioned upper limit or less, and it is presumed that bleeding of the aromatic compounds having 7 to 10 carbon atoms, a decrease in initial adhesive strength, and gelation or aggregation of the adhesive composition can be prevented.

[0023] The content of aromatic compounds having 7 to 10 carbon atoms per 100 parts by mass of solids in the chloroprene polymer latex composition can be analyzed by gas chromatography, and specifically, can be calculated by the method described in the Examples. The total content of aromatic compounds having 7 to 10 carbon atoms per 100 parts by mass of solids in the chloroprene polymer latex composition can be adjusted by adding an aromatic compound having 7 to 10 carbon atoms to the chloroprene polymer latex. Furthermore, when raw materials used in the polymerization of a chloroprene polymer may contain an aromatic compound having 7 to 10 carbon atoms, or when an aromatic compound having 7 to 10 carbon atoms may be generated as a by-product during the production of a chloroprene polymer, the content of aromatic compounds having 7 to 10 carbon atoms can be controlled by adjusting the production conditions of the chloroprene polymer, including the concentration conditions and dilution conditions of the chloroprene polymer latex.

[0024] In the chloroprene polymer latex composition according to one embodiment of the present invention, the total content of 4-chlorovinylbenzene, 2-methylbenzyl chloride, and 3-methylbenzyl chloride is preferably 0.00100 parts by mass or less relative to 100 parts by mass of the solid content in the chloroprene polymer latex composition. The total content of 4-chlorovinylbenzene, 2-methylbenzyl chloride, and 3-methylbenzyl chloride relative to 100 parts by mass of the solid content in the chloroprene polymer latex composition is, for example, 0, 0.00010, 0.00020, 0.00030, 0.00040, 0.00050, 0.00060, 0.00070, 0.00080, 0.00090, or 0.00100 parts by mass, and may be within a range between any two of the values ​​exemplified here. In the chloroprene polymer latex composition according to one embodiment of the present invention, the total content of compounds in which one or more hydrogen atoms bonded to an aromatic ring are substituted with a chlorine atom or a substituent containing a chlorine atom can be within the above-mentioned range, and the total content of compounds in which one or more hydrogen atoms bonded to an aromatic ring are substituted with a halogen or a substituent containing a halogen can be within the above-mentioned range, relative to 100 parts by mass of the solid content of the chloroprene polymer latex composition.

[0025] The chloroprene polymer latex composition according to one embodiment of the present invention may be free of 4-chlorovinylbenzene, 2-methylbenzyl chloride, 3-methylbenzyl chloride, and 4-methylbenzyl chloride, and may be free of a compound in which one or more hydrogen atoms bonded to an aromatic ring are substituted with a chlorine atom, or a compound substituted with a substituent containing a chlorine atom. Furthermore, the chloroprene polymer latex composition according to one embodiment of the present invention may be free of a compound in which one or more hydrogen atoms bonded to an aromatic ring are substituted with a halogen, or a compound substituted with a substituent containing a halogen. For example, the content of these compounds containing chlorine or the like can be controlled by appropriately controlling the polymerization conditions for the chloroprene polymer to suppress the production of by-products.

[0026] The chloroprene polymer latex composition according to one embodiment of the present invention may contain agents used in producing a chloroprene polymer latex, such as an emulsifier, a dispersant, etc. These components will be described later in the description of the production method.

[0027] 1.3 Characteristics of Chloroprene Polymer Latex Composition The surface tension of the chloroprene polymer latex composition according to one embodiment of the present invention can be greater than 30.0 mN / m and less than 45.0 mN / m. The surface tension of the chloroprene polymer latex composition is, for example, 30.5, 31.0, 32.0, 34.0, 36.0, 38.0, 40.0, 42.0, 44.0, or 44.5 mN / m, and may be within a range between any two of the values ​​exemplified here. When the surface tension of the chloroprene polymer latex composition is within the above range, the wettability of an adhesive composition containing the chloroprene polymer latex composition to an adherend and its stability during blending are improved, and the initial adhesive strength is further improved.

[0028] The surface tension of the chloroprene polymer latex composition can be the surface tension of a chloroprene polymer latex composition having a solids concentration of 55% by mass, and specifically, can be measured by the method described in the Examples. The surface tension of the chloroprene polymer latex composition can be controlled, for example, by adjusting the production conditions of the chloroprene polymer latex, including the concentration conditions and dilution conditions of the chloroprene polymer latex, or by adjusting the presence or absence and amount of an aromatic compound having 7 to 10 carbon atoms added to the chloroprene polymer latex, thereby adjusting the total content of the aromatic compound having 7 to 10 carbon atoms.

[0029] The chloroprene polymer latex composition according to one embodiment of the present invention is a test adhesive composition containing 25 parts by mass of an acrylic emulsion and 11 parts by mass of a pH adjuster per 100 parts by mass of the chloroprene polymer latex composition, and the initial adhesive strength 1 measured by the following method is 2.1 N / cm ２ or more, and / or initial adhesive strength 2 is 5.0 N / cm ２ It is preferable that this is equal to or greater than this.

[0030] The initial adhesive strength 1 is, for example, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0 N / cm ２ and may be in a range between any two of the values ​​given here.

[0031] The initial adhesive strength 2 is, for example, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0 N / cm ２ and may be in a range between any two of the values ​​given here.

[0032] <Initial adhesive strength> Density 30kg / m ３Two pieces of urethane foam (thickness 20 mm × length 50 mm × width 50 mm) were used as adherends, and the test adhesive composition was applied at 70 g / m under an atmosphere of 23°C. ２ The adhesive was sprayed onto each adherend so that the adhesive was applied. After application, while the adhesive was still wet, the adhesive surfaces of the urethane foams were overlapped, and the 40 mm thick adherends (laminates) were compressed to 20 mm and held for 10 seconds. After leaving them in a 23°C atmosphere for 1 minute (initial adhesive strength 1) or 15 minutes (initial adhesive strength 2), a tensile test was immediately conducted in the direction perpendicular to the adhesive surface using a tensile tester (A&D Tensilon; tensile speed 200 mm / min) to measure the adhesive strength.

[0033] 2. Method for Producing Chloroprene Polymer Latex Composition The method for producing the chloroprene polymer latex composition according to the present invention is not particularly limited. The method for producing the chloroprene polymer latex composition according to one embodiment of the present invention may include a polymerization step of polymerizing raw material monomers containing chloroprene to obtain a chloroprene polymer latex containing a chloroprene polymer.

[0034] When producing a chloroprene polymer, raw material monomers are polymerized by a polymerization method such as emulsion polymerization, solution polymerization, suspension polymerization, or bulk polymerization. Among these polymerization methods, emulsion polymerization is preferred because it offers various advantages, such as ease of control, ease of polymer isolation from the polymerization-finished liquid, and a relatively fast polymerization rate. A production method according to one embodiment of the present invention may include an emulsion polymerization step in which raw material monomers, including chloroprene and, if necessary, other monomers, are polymerized in the presence of an emulsifier to obtain a chloroprene polymer latex containing a chloroprene polymer. In the emulsion polymerization step, the raw material monomers are emulsion-polymerized using an emulsifier, a dispersant, a polymerization initiator, a chain transfer agent, a reducing agent, and the like, as appropriate. When the target polymerization rate is reached, a polymerization terminator is added to obtain a chloroprene polymer latex. Furthermore, unreacted monomers may be removed by a concentration method such as vacuum distillation. Furthermore, one or more concentration and dilution steps may be subsequently performed.

[0035] (Raw Material Monomers) In the polymerization step, the raw material monomers include chloroprene and may further include other monomers copolymerizable with chloroprene. The other monomers are as described above as monomers that derive the monomer units that can be contained in the chloroprene-based polymer. The type and amount of each monomer charged are preferably adjusted so that the content of each monomer unit in the resulting chloroprene-based polymer falls within the above-described numerical range.

[0036] (Emulsifier) ​​The emulsifier preferably contains rosin acid and / or a rosin acid salt. Examples of rosin acid salts include alkali metal salts such as sodium salts and potassium salts. The amount of rosin acid and rosin acid salt added may be 3.0 to 10.0 parts by mass per 100 parts by mass of the raw material monomer used. The amount of rosin acid and rosin acid salt added may be, for example, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, or 10.0 parts by mass, and may be within a range between any two of the values ​​exemplified here.

[0037] The rosin acid and / or rosin acid salt may contain a conjugated resin acid component and a non-conjugated resin acid component. Examples of the conjugated resin acid component include abietic acid, neoabietic acid, palustric acid, levopimaric acid, and salts thereof. Examples of the non-conjugated resin acid component include dehydroabietic acid, pimaric acid, isopimaric acid, dihydropimaric acid, dihydroabietic acid, and salts thereof. The rosin acid and / or rosin acid salt may not contain a conjugated resin acid component.

[0038] The emulsifier may also include emulsifiers and dispersants other than rosin acid and rosin acid salts. Examples of emulsifiers and dispersants other than rosin acid and rosin acid salts include cationic, anionic, and nonionic emulsifiers and dispersants. In one embodiment of the present invention, the emulsifier used in the emulsion polymerization process may include rosin acid and / or rosin acid salts, and an anionic emulsifier or dispersant. As anionic emulsifiers and dispersants, sulfate- or sulfonate-based anionic emulsifiers and dispersants are preferably used in combination to stabilize the chloroprene polymer latex when a pH adjuster is added. Specific examples include alkyl sulfonates having 8 to 20 carbon atoms, alkyl aryl sulfates, condensates of sodium β-naphthalene sulfonate and formaldehyde, and sodium alkyl diphenyl ether disulfonates. The amount of anionic emulsifier or dispersant added may be 0.05 to 5 parts by mass per 100 parts by mass of the raw material monomers. The amount of anionic emulsifier or dispersant added is, for example, 0.05, 0.1, 0.2, 0.3, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 parts by mass relative to 100 parts by mass of the raw material monomer, and may be within a range between any two of the numerical values ​​exemplified here.

[0039] (Chain Transfer Agent) In the emulsion polymerization step, it is preferable to add a chain transfer agent to adjust the molecular weight, molecular weight distribution, and toluene insoluble content of the chloroprene polymer. The chain transfer agent may be added at the beginning of polymerization or during polymerization. Preferred chain transfer agents are long-chain alkyl mercaptans such as n-dodecyl mercaptan and t-dodecyl mercaptan, and dialkyl xanthogen disulfides such as diisopropyl xanthogen disulfide and diethyl xanthogen disulfide. Long-chain alkyl mercaptans are more preferred because they facilitate control of the molecular weight and toluene insoluble content. The chain transfer agent can be used alone or in combination of two or more. The total amount of chain transfer agent added during emulsion polymerization is preferably 0.005 to 0.12 parts by mass per 100 parts by mass of the raw material monomers. The total amount of chain transfer agent added is, for example, 0.005, 0.01, 0.05, 0.10, 0.11, or 0.12 parts by mass, and may be within a range between any two of the values ​​exemplified here.

[0040] (Initiator) As the polymerization initiator, a conventional radical polymerization initiator can be used. Specifically, organic or inorganic peroxides such as benzoyl peroxide, potassium persulfate, ammonium persulfate, etc., and azo compounds such as azobisisobutyronitrile, etc., can be used. Furthermore, a co-catalyst such as anthraquinone sulfonate, potassium sulfite, sodium sulfite, etc. can be used in combination as appropriate.

[0041] (Potassium hydroxide and sodium hydroxide) In the emulsion polymerization step, sodium hydroxide and / or potassium hydroxide can be used. The amount of sodium hydroxide and potassium hydroxide can be 0.01 to 2.0 parts by mass per 100 parts by mass of the raw material monomers.

[0042] (Reducing Agent) A reducing agent can be added in the emulsion polymerization step. Examples of the reducing agent include potassium pyrosulfite, potassium sulfite, potassium hydrogen sulfite, potassium phosphate, potassium hydrogen phosphate, sodium hydrogen sulfite, sodium sulfate, and thiourea dioxide. The amount of the reducing agent added can be 0.005 to 3.0 parts by mass per 100 parts by mass of the raw material monomers used in the polymerization step. Note that a reducing agent need not be used.

[0043] In a polymerization process according to one embodiment of the present invention, all of the raw material monomers and chemicals to be used in the polymerization process can be charged into the polymerization vessel before the start of polymerization, and then polymerization can be initiated. Alternatively, at least a portion of the raw material monomers and / or chemicals to be used in the polymerization process can be charged into the polymerization vessel before the start of polymerization, and the remainder can be added in portions after the start of polymerization. When at least a portion of the raw material monomers and chemicals are charged into the polymerization vessel before the start of polymerization, and the remaining raw material monomers and / or chemicals are added after the start of polymerization, the remaining raw material monomers and / or chemicals can be added in portions in one or more portions, or can be added continuously at a constant flow rate. In one embodiment of the present invention, at least a portion of the raw material monomers can be added in portions after the start of polymerization.

[0044] (Polymerization Conversion Rate) The polymerization conversion rate of raw material monomers during emulsion polymerization of chloroprene-based polymers and the like is preferably 50% by mass or more but less than 90% by mass. The polymerization conversion rate (mass%) is calculated by [(polymer mass / total monomer mass) × 100]. Hereinafter, the polymerization conversion rate may also be simply referred to as the polymerization rate.

[0045] (Polymerization Temperature) The chloroprene polymer can be polymerized, for example, in the range of 0 to 45° C., and is preferably polymerized at a low temperature of 5 to 20° C. The polymerization temperature is, for example, 0, 5, 10, 15, 20, 25, 30, 35, 40, or 45° C., and may be within a range between any two of the values ​​exemplified here.

[0046] (Polymerization Terminator) Generally, in the production of chloroprene polymers, a polymerization terminator is added to terminate the reaction when a predetermined polymerization rate is reached in order to obtain a polymer with a desired molecular weight and distribution. The polymerization terminator is not particularly limited, but examples thereof include phenothiazine, p-t-butylcatechol, hydroquinone, hydroquinone monomethyl ether, and diethylhydroxylamine.

[0047] Furthermore, to the chloroprene polymer-containing latex obtained by the production method of one embodiment of the present invention, a freezing stabilizer, an emulsion stabilizer, a viscosity modifier, an antioxidant, a preservative, and the like can be optionally added after polymerization, as long as the effects of the present invention are not impaired. The production method of a chloroprene polymer latex according to one embodiment of the present invention may include a step of adding a surfactant after polymerization termination. Examples of the surfactant include nonionic surfactants. Examples of the nonionic surfactant include polyoxyalkylene phenyl ether-based surfactants, polyoxyalkylene alkyl ether-based surfactants, polyoxyethylene sorbitan fatty acid ester-based surfactants, polyoxyethylene sorbitol fatty acid ester-based surfactants, sorbitan fatty acid ester-based surfactants, glycerin fatty acid ester-based surfactants, polyoxyethylene alkylamine-based surfactants, polyoxyethylene fatty acid ester-based surfactants, and alkyl alkanolamide-based surfactants. The nonionic surfactant preferably contains at least one of polyoxyalkylene phenyl ether-based and polyoxyalkylene alkyl ether-based surfactants, more preferably contains at least one of polyoxyethylene phenyl ether-based and polyoxyethylene alkyl ether-based surfactants, and even more preferably contains a polyoxyethylene styryl phenyl ether-based surfactant.

[0048] Polyoxyalkylene alkyl ether and polyoxyalkylene phenyl ether surfactants are RO(EO) ｎ (PO) ｍIn the formula, R is a linear or branched alkyl group having 8 to 30 carbon atoms or an unsubstituted or substituted phenyl group, preferably a linear or branched alkyl group having 8 to 12 carbon atoms or an unsubstituted or substituted phenyl group, and more preferably a group in which a hydrogen atom of the phenyl group is replaced by a styryl group C ６ H ５ -CH(CH ３ )- group. EO represents an ethylene oxide group, and PO represents an alkylene oxide group having 3 or more carbon atoms, such as a propylene oxide group or a butylene oxide group, and the arrangement thereof may be block or random. n and m each represent a value from 0 to 100, preferably from 0 to 50. Note that n+m>0.

[0049] The amount of the nonionic surfactant added is preferably 0.4 parts by mass or less relative to 100 parts by mass of the chloroprene polymer. The amount of the nonionic surfactant added may be, for example, 0, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, or 0.40 parts by mass, and may be within a range between any two of the values ​​exemplified here. The method for producing a chloroprene polymer latex according to one embodiment of the present invention may not include a step of adding a surfactant after polymerization termination. The surfactant may be added before or after adjusting the solids concentration.

[0050] The latex containing a chloroprene polymer obtained after the chloroprene polymer polymerization step can be referred to as a chloroprene polymer latex. The chloroprene polymer latex according to one embodiment of the present invention can contain a chloroprene polymer obtained in the chloroprene polymer polymerization step and water. When the polymer contained in the chloroprene polymer according to the present invention is obtained by emulsion polymerization, the chloroprene polymer latex can further contain raw materials used in the emulsion polymerization step, such as an emulsifier.

[0051] A method for producing a chloroprene polymer latex according to one embodiment of the present invention may include a concentration step such as vacuum distillation. The concentration step can remove unreacted monomers and adjust the solids concentration of the chloroprene polymer latex. The production method according to one embodiment of the present invention may include one or more concentration steps. The concentration step may be, for example, one, two, three, four, or five times, or may be within a range between any two of the values ​​exemplified herein. The production method according to one embodiment of the present invention may include a dilution step by adding water, which dilutes the concentrations of the components in the chloroprene polymer latex and adjusts the solids concentration of the chloroprene polymer latex. The production method according to one embodiment of the present invention may include one or more dilution steps. The concentration step may be, for example, one, two, three, four, or five times, or may be within a range between any two of the values ​​exemplified herein. When raw materials or the like used in polymerization of a chloroprene polymer may contain an aromatic compound having 7 to 10 carbon atoms, or when an aromatic compound having 7 to 10 carbon atoms may be generated as a by-product during production of a chloroprene polymer, the content of the aromatic compound having 7 to 10 carbon atoms can be controlled by adjusting the concentration conditions and number of concentration steps, or the dilution conditions and number of dilution steps of the chloroprene polymer latex.

[0052] (Solid Content Concentration) The solid content concentration of the chloroprene polymer latex is not particularly limited, but can be adjusted to 40 to 65 mass %. The solid content concentration of the chloroprene polymer latex can be controlled by adjusting the blending ratio including a solvent such as water during emulsion polymerization of the chloroprene polymer, or by performing a concentration process and a dilution process.

[0053] A method for producing a chloroprene polymer latex composition according to one embodiment of the present invention may include an aromatic compound addition step of adding an aromatic compound having 7 to 10 carbon atoms to the chloroprene polymer latex. The types of aromatic compounds to be added are as described above. In the aromatic compound addition step, the aromatic compound having 7 to 10 carbon atoms can be added so that the total content of the aromatic compound having 7 to 10 carbon atoms per 100 parts by mass of the solid content of the chloroprene polymer latex composition obtained falls within the above-described numerical range. For example, in the aromatic compound addition step, 0.0001 to 0.0100 parts by mass of the aromatic compound having 7 to 10 carbon atoms is added per 100 parts by mass of the solid content of the chloroprene polymer latex composition. The total amount of the aromatic compounds having 7 to 10 carbon atoms added is, for example, 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.0010, 0.0015, 0.0020, 0.0025, 0.0030, 0.0035, 0.0040, 0.0045, 0.0050, 0.0055, 0.0060, 0.0065, 0.0070, 0.0075, 0.0080, 0.0085, 0.0090, 0.0095, or 0.0100 parts by mass, and may be within a range between any two of the numerical values ​​exemplified here.

[0054] In one embodiment of the present invention, a composition containing a chloroprene polymer and an aromatic compound having 7 to 10 carbon atoms, obtained after performing the concentration step, dilution step, and / or aromatic compound addition step as necessary, can be referred to as a chloroprene polymer latex composition.

[0055] 3. Adhesive Composition An adhesive composition according to one embodiment of the present invention comprises the above-described chloroprene polymer latex composition and an aromatic compound having 7 to 10 carbon atoms. The adhesive composition according to one embodiment of the present invention comprises a chloroprene polymer and an aromatic compound having 7 to 10 carbon atoms, and the total content of the aromatic compound having 7 to 10 carbon atoms is preferably 0.0001 to 0.0100 parts by mass per 100 parts by mass of solids in the adhesive composition. The adhesive composition according to one embodiment of the present invention preferably has a total content of the aromatic compound having 7 to 10 carbon atoms of 0.0001 to 0.0100 parts by mass, and more preferably 0.0002 to 0.0091 parts by mass per 100 parts by mass of solids in the adhesive composition. The total content of the aromatic compounds having 7 to 10 carbon atoms per 100 parts by mass of the solid content in the adhesive composition is, for example, 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.0010, 0.0015, 0.0020, 0.0025, 0.0030, 0.0035, 0.0040, 0.0045, 0.0050, 0.0055, 0.0060, 0.0065, 0.0070, 0.0075, 0.0080, 0.0085, 0.0090, 0.0095, or 0.0100 parts by mass, or may be within a range between any two of the values ​​exemplified here. The adhesive composition according to one embodiment of the present invention may contain a pH adjuster, a polymer emulsion, and / or other necessary agents.

[0056] 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.

[0057] 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 solids content of the chloroprene polymer latex composition. 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.

[0058] 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).

[0059] 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.

[0060] 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), 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 initial adhesive strength.

[0061] 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.

[0062] The adhesive composition according to one embodiment of the present invention has an initial adhesive strength 1 measured by the above method of 2.1 N / cm ２ or more, and / or initial adhesive strength 2 is 5.0 N / cm ２ It is preferable that this is equal to or greater than this.

[0063] The initial adhesive strength 1 is, for example, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0 N / cm ２ and may be in a range between any two of the values ​​given here.

[0064] The initial adhesive strength 2 is, for example, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0 N / cm ２ and may be in a range between any two of the values ​​given here.

[0065] 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.

[0066] 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.

[0067] (Production of Chloroprene Polymer Latex A) A 10-liter reactor was charged with 90 parts by weight of water, 4.5 parts by weight of disproportionated rosin acid, 0.5 parts by weight of potassium hydroxide, and 0.3 parts by weight of sodium salt of formaldehyde-naphthalenesulfonic acid condensate under a nitrogen stream. After dissolution, 100 parts by weight of chloroprene monomer and 0.1 parts by weight of n-dodecyl mercaptan were added with stirring. Potassium persulfate was used as an initiator, and polymerization was carried out at 10°C under a nitrogen atmosphere. When the conversion reached 83%, a phenothiazine emulsion was added to terminate the polymerization. After adding 0.20 parts by weight of polyoxyethylene styrylphenyl ether, the polymerization solution was distilled under reduced pressure to remove unreacted monomer and concentrated to a solids concentration of 63% by weight (first concentration). Water was added to the resulting solution to a solids concentration of 55% by weight, and the solution was again concentrated to a solids concentration of 63% by weight (second concentration). Further, water was added to the mixture to adjust the solid content to 50% by mass, and the mixture was concentrated again to obtain a chloroprene polymer latex A having a solid content of 55% by mass (third concentration). The toluene-insoluble content of the chloroprene polymer contained in the chloroprene polymer latex A was 10%.

[0068] Example 1 A chloroprene polymer latex composition according to Example 1 was obtained by adding 0.0016 parts by mass of toluene to 100 parts by mass of the chloroprene polymer latex A.

[0069] (Examples 2 to 9, Comparative Examples 1 to 3) Chloroprene polymer latex compositions were obtained in the same manner as in Example 1, except that the types and amounts of aromatic compounds having 7 to 10 carbon atoms to be added were as shown in Table 1.

[0070] [Evaluation of Chloroprene Polymer Latex Composition] <Concentration and Content of Aromatic Compounds Having 7 to 10 Carbon Atoms> The aromatic compounds having 7 to 10 carbon atoms in the chloroprene polymer latex composition were analyzed by gas chromatography (headspace method). 0.03 g of the chloroprene polymer latex composition was placed in a tightly sealed vial, and measurement was performed under the following measurement conditions. (Gas chromatography conditions) Apparatus: GC-1700 (Shimadzu Corporation) Column: Pora PLOT U φ0.53 mm×25 m (film thickness 20 μm) Column temperature: 130° C. → 2° C. / min → 190° C. Inlet temperature: 180° C. Detector temperature: 190° C. Detector: FID Headspace sampler: TurboMatrix HS40 The concentration [ppm] of the aromatic compound having 7 to 10 carbon atoms in the chloroprene polymer latex composition was determined using a calibration curve of the area of ​​the peak attributable to the aromatic compound having 7 to 10 carbon atoms obtained by the measurement and the content of the aromatic compound having 7 to 10 carbon atoms. The results are shown in Table 1. From the determined concentration of the aromatic compound having 7 to 10 carbon atoms in the chloroprene polymer latex composition, the amount [parts by mass] of the aromatic compound having 7 to 10 carbon atoms per 100 parts by mass of the solid content in the chloroprene polymer latex composition was calculated using the following formula. The results are shown in Table 1. Amount [parts by mass] of the aromatic compound having 7 to 10 carbon atoms per 100 parts by mass of the solid content in the chloroprene polymer latex composition = 100 × (concentration of the aromatic compound having 7 to 10 carbon atoms [ppm]) / 1,000,000 × 100 / (solid content concentration of the chloroprene polymer latex composition [% by mass])

[0071] <Toluene-Insoluble Content of Chloroprene Polymer> The toluene-insoluble content of the chloroprene polymer contained in each chloroprene polymer latex composition was determined by the following method. First, a chloroprene polymer obtained by freeze-drying the chloroprene polymer latex was cut into 2 mm squares to obtain a test piece. The test piece was placed in a conical beaker and dissolved in 80 g of toluene for 16 hours. Subsequently, after centrifugation, the gel content (insoluble content) was separated using a 200-mesh wire netting. The gel content was then dried and the mass of the dried product was measured. The toluene-insoluble content of the chloroprene polymer was determined by the following formula, where Ag is the chloroprene polymer after freeze-drying and B g is the gel content (insoluble content) separated from the mixture dissolved in toluene. The measurement results are shown in Table 1. Toluene-insoluble content (gel content) = B / A × 100 (%)

[0072] <Surface Tension> The surface tension of each chloroprene polymer latex composition was measured by the hanging drop method using DM-301 (manufactured by Kyowa Interface Science Co., Ltd., amount of solution used: 7.5 μL) at 23° C. The measurement results are shown in Table 1.

[0073] [Evaluation of Adhesive Composition] <Preparation of Adhesive Composition> 25 parts by mass of an acrylic emulsion (product name "Acronal Proof 1299", BASF) and 11 parts by mass of glycine as a pH adjuster were added to 100 parts by mass of the solids content of the chloroprene polymer latex composition obtained above, and the mixture was stirred using a Three-One Motor to prepare an adhesive composition. The initial adhesive strength of the obtained adhesive composition was measured by the following method. The measurement results are shown in Table 1.

[0074] <Initial adhesive strength> Density 30kg / m ３ Two pieces of urethane foam (thickness 20 mm × length 50 mm × width 50 mm) were used as adherends, and the adhesive composition was applied at 70 g / m under an atmosphere of 23°C. ２The adhesive composition was spray-coated onto each adherend so that the adhesive composition was uniform. After application, while the adhesive composition was still wet, the adhesive surfaces of the urethane foams were placed together, and the 40 mm thick adherends (laminates) were compressed to 20 mm and held for 10 seconds. After leaving the laminate in a 23°C atmosphere for 1 minute (initial adhesive strength 1) or 15 minutes (initial adhesive strength 2), a tensile test was immediately performed in the direction perpendicular to the adhesive surface using a tensile tester (A&D Tensilon; tensile speed 200 mm / min) to measure the adhesive strength.

[0075]

Claims

1. A chloroprene polymer latex composition comprising a chloroprene polymer and an aromatic compound having 7 to 10 carbon atoms, wherein the total content of the aromatic compound having 7 to 10 carbon atoms is 0.0001 to 0.0100 parts by mass per 100 parts by mass of solids in the chloroprene polymer latex composition.

2. The chloroprene polymer latex composition according to claim 1, wherein the aromatic compound having 7 to 10 carbon atoms comprises at least one selected from the group consisting of toluene, ethylbenzene, xylene, and styrene.

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