Latex

Abstract

Disclosed is a latex which contains: rubber particles that contain an ethylene butene diene copolymer; an emulsifier; and water. The content of the rubber particles may be 15 mass% to 70 mass% inclusive based on the mass of the latex, and the content of the emulsifier may be 2 parts by mass to 10 parts by mass inclusive with respect to 100 parts by mass of the rubber particles.

Description

latex

[0001] The present disclosure relates to latexes containing rubber particles.

[0002] Latex containing rubber such as chlorosulfonated polyethylene (CSM) is used in various applications such as adhesives (see, for example, Patent Document 1).

[0003] International Publication No. 2012 / 141020

[0004] One aspect of the present disclosure relates to a latex with excellent pH stability.

[0005] The present disclosure includes the following: [1] A latex comprising rubber particles containing an ethylene-butene-diene copolymer, an emulsifier, and water. [2] The latex according to [1], wherein the content of the rubber particles is 15% by mass or more and 70% by mass or less, based on the mass of the latex, and the content of the emulsifier is 2 parts by mass or more and 10 parts by mass or less, based on 100 parts by mass of the rubber particles. [3] The latex according to [1] or [2], wherein, based on the total mass of the ethylene-butene-diene copolymer, a proportion of monomer units derived from ethylene is 40% by mass or more and 80% by mass or less, a proportion of monomer units derived from butene is 5% by mass or more and 58% by mass or less, and a proportion of monomer units derived from 5-ethylidene-2-norbornene is 2% by mass or more and 15% by mass or less.

[0006] A stable latex that changes little over time can be provided. For example, a latex that has excellent pH stability can be provided. A stable latex that changes little over time is useful in many applications.

[0007] The present invention is not limited to the following examples.

[0008] (Latex) An example of a latex according to the present disclosure includes rubber particles containing ethylene-butene-diene copolymer (hereinafter sometimes referred to as "EBDM"), an emulsifier, and water. The latex is a dispersion in which the rubber particles are dispersed in water.

[0009] EBDM is a copolymer containing ethylene, butene, and a diene as monomer units, and can be a random copolymer containing these monomer units. The butene may be 1-butene or 2-butene. The diene may be a non-conjugated diene. The non-conjugated diene may be 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, or dicyclopentadiene.

[0010] The EBDM may be an ethylene-1-butene-5-ethylidene-2-norbornene copolymer (EBDM-1). EBDM-1 can be represented, for example, by the following formula: In the formula, x, y, and z represent integers of 1 or greater. x is the number of monomer units derived from ethylene, y is the number of monomer units derived from 1-butene, and z is the number of monomer units derived from 5-ethylidene-2-norbornene. EBDM-1 can be a random copolymer containing these monomer units.

[0011] The proportion of ethylene-derived monomer units in the EBDM may be 40% by mass or more and 80% by mass or less, based on the total mass of the EBDM. The proportion of ethylene-derived monomer units may be 45% by mass or more and 55% by mass or less, based on the total mass of the EBDM. The proportion of ethylene-derived monomer units may be 40% by mass or more and 55% by mass or less, 45% by mass or more and 80% by mass or less, or 45% by mass or more and 55% by mass or less, based on the total mass of the EBDM.

[0012] The proportion of butene-derived monomer units in the EBDM may be 5% by mass or more and 58% by mass or less, based on the total mass of the EBDM. The proportion of butene-derived monomer units may be 35% by mass or more and 50% by mass or less, based on the total mass of the EBDM. The proportion of butene-derived monomer units may be 5% by mass or more and 50% by mass or less, 35% by mass or more and 58% by mass or less, or 35% by mass or more and 50% by mass or less, based on the total mass of the EBDM.

[0013] The proportion of diene-derived monomer units in the EBDM may be 2% by mass or more and 15% by mass or less, based on the total mass of the EBDM. The proportion of diene-derived monomer units may be 5% by mass or more and 10% by mass or less, based on the total mass of the EBDM. The proportion of diene-derived monomer units may be 2% by mass or more and 10% by mass or less, 5% by mass or more and 15% by mass or less, or 5% by mass or more and 10% by mass or less, based on the total mass of the EBDM.

[0014] The EBDM content in the rubber particles may be 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 98% by mass or more and 100% by mass or less, based on the mass of the rubber particles.

[0015] The volumetric median diameter of the rubber particles may be 0.5 μm or more and 50 μm or less. The volumetric median diameter of the rubber particles may be 1.0 μm or more and 40 μm or less, 30 μm or less, or 25 μm or less. The volumetric median diameter of the rubber particles may be 0.5 μm or more and 40 μm or less, 30 μm or less, or 25 μm or less. The volumetric median diameter of the rubber particles may be 1.0 μm or more and 50 μm or less, 40 μm or less, 30 μm or less, or 25 μm or less. A small median diameter of the rubber particles is advantageous in that the rubber particles are less likely to float or settle over time in the latex. The median diameter here is the cumulative 50% particle size in the volumetric particle size distribution determined by laser diffraction.

[0016] The content of rubber particles in the latex may be 15% by mass or more and 70% by mass or less, based on the mass of the latex. The content of rubber particles may be 25% by mass or more, or 30% by mass or more, and 60% by mass or less, or 50% by mass or less, based on the mass of the latex. The content of rubber particles in the latex may be 15% by mass or more and 60% by mass or less, or 50% by mass or less, based on the mass of the latex. The content of rubber particles in the latex may be 25% by mass or more and 70% by mass or less, 60% by mass or less, or 50% by mass or less, based on the mass of the latex. The content of rubber particles in the latex may be 30% by mass or more and 70% by mass or less, 60% by mass or less, or 50% by mass or less, based on the mass of the latex.

[0017] The emulsifier is selected so as to form a latex in which rubber particles are stably dispersed. Appropriate selection of the type and amount of emulsifier can contribute to further improving the stability of the latex over time, controlling the particle size of the rubber particles, and improving film-forming properties and adhesion.

[0018] The emulsifier may be an anionic surfactant, a nonionic surfactant, a cationic surfactant, or an amphoteric surfactant.

[0019] For example, the emulsifier may comprise one or more selected from the group consisting of aliphatic carboxylates having 6 to 24 carbon atoms, sulfonates having a carboxylic acid ester group formed from an aliphatic alcohol having 6 to 24 carbon atoms and a carboxylic acid, aromatic sulfonates having an aromatic group and an alkyl group having 6 to 24 carbon atoms bonded to the aromatic group, sulfonates having a carboxylic acid amide group having 6 to 24 carbon atoms, betaines having an alkyl group having 6 to 24 carbon atoms, salts of esters formed from an alkyl group having 6 to 24 carbon atoms and sulfuric acid, carboxylates having an alicyclic group containing a conjugated double bond, salts of esters formed from an alcohol having an alkyl group having 6 to 24 carbon atoms and a polyoxyethylene group and sulfuric acid, salts of half esters of copolymers of aromatic vinyl compounds and acid anhydrides, carboxylates having a carboxylic acid amide group having 6 to 24 carbon atoms, salts of condensates of polycyclic aromatic hydrocarbons having a sulfonic acid group and formaldehyde, and disulfonates having a polyoxyalkylene group.

[0020] From the viewpoint of stable formation of rubber particles having a small particle size, the emulsifier may contain at least one selected from the group consisting of aliphatic carboxylates having 6 to 24 carbon atoms, sulfonates having a carboxylic acid ester group formed from an aliphatic alcohol having 6 to 24 carbon atoms and a carboxylic acid, aromatic sulfonates having an aromatic group and an alkyl group having 6 to 24 carbon atoms bonded to the aromatic group, sulfonates having a carboxylic acid amide group having 6 to 24 carbon atoms, betaines having an alkyl group having 6 to 24 carbon atoms, and salts of an ester formed from an alkyl group having 6 to 24 carbon atoms and sulfuric acid.

[0021] The carbon number of the aliphatic carboxylate having 6 to 24 carbon atoms may be 10 to 20. An example of the aliphatic carboxylate having 6 to 24 carbon atoms includes potassium oleate. Such an aliphatic carboxylate can be formed by contacting the corresponding aliphatic carboxylic acid with a compound that neutralizes the aliphatic carboxylic acid to form a salt (e.g., an alkali metal hydroxide) during the process of forming an emulsified dispersion (emulsion). The formed aliphatic carboxylate can be used as an emulsifier.

[0022] In the sulfonate salt having a carboxylic acid ester group formed from an aliphatic alcohol having 6 to 24 carbon atoms and a carboxylic acid, the carbon number of the aliphatic alcohol may be 10 to 20. An example of a sulfonate salt having a carboxylic acid ester group formed from an aliphatic alcohol having 6 to 24 carbon atoms and a carboxylic acid includes sodium di-2-ethylhexyl sulfosuccinate (an example of a commercially available product: NOF Corporation, trade name "Rapisol A-80").

[0023] In the aromatic sulfonate having an aromatic group and an alkyl group having 6 to 24 carbon atoms bonded to the aromatic group, the alkyl group may have 10 to 20 carbon atoms. An example of an aromatic sulfonate having an aromatic group and an alkyl group having 6 to 24 carbon atoms bonded to the aromatic group includes sodium alkyl(C10-16)benzenesulfonate (an example of a commercially available product: NOF Corporation, trade name "Newlex R").

[0024] Examples of sulfonates having a carboxylic acid amide group having 6 to 24 carbon atoms include fatty acid methyl taurate sodium salt (an example of a commercially available product: NOF Corporation, trade name "Diapon S").

[0025] The number of carbon atoms in the alkyl group in the betaine having an alkyl group having 6 to 24 carbon atoms may be 10 to 20. An example of a betaine having an alkyl group having 6 to 24 carbon atoms includes lauryl dimethylaminoacetic acid betaine (an example of a commercially available product: manufactured by NOF Corporation, trade name "Nissan Anon BL").

[0026] The number of carbon atoms in the alcohol in the salt of an ester formed from an alcohol having 6 to 24 carbon atoms and sulfuric acid may be 10 to 20. An example of the salt of an ester formed from an alcohol having 6 to 24 carbon atoms and sulfuric acid includes sodium lauryl sulfate.

[0027] Examples of carboxylic acid salts having an alicyclic group containing a conjugated double bond include potassium rosinate (an example of a commercially available product: manufactured by Arakawa Chemical Industries, Ltd., trade name "LONDIS K-25").

[0028] The number of carbon atoms in the alkyl group in the salt of an ester formed from sulfuric acid and an alcohol having an alkyl group with 6 to 24 carbon atoms and a polyoxyethylene group may be 10 to 20. An example of the salt of an ester formed from sulfuric acid and an alcohol having an alkyl group with 6 to 24 carbon atoms and a polyoxyethylene group includes sodium polyoxyethylene lauryl ether sulfate (an example of a commercially available product: NOF Corporation, trade name "Persoft EF").

[0029] Examples of salts of half esters of copolymers of aromatic vinyl compounds and acid anhydrides include styrene-maleic acid copolymer half ester ammonium salt (an example of a commercially available product: manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name "DKS Discoat N-14").

[0030] The number of carbon atoms in the carboxylic acid amide group in the carboxylic acid salt having 6 to 24 carbon atoms may be 10 to 20. Examples of the carboxylic acid salt having a carboxylic acid amide group having 6 to 24 carbon atoms include N-lauroylmethylalanine sodium (an example of a commercially available product: NOF Corporation, trade name "Softtilt AS-L").

[0031] Examples of salts of condensates of polycyclic aromatic hydrocarbons having sulfonic acid groups with formaldehyde include sodium salt of β-naphthalenesulfonic acid formalin condensate (an example of a commercially available product: Kao Corporation, trade name "Demol N").

[0032] The content of the emulsifier may be 2 parts by mass or more and 10 parts by mass or less per 100 parts by mass of rubber particles. The content of the emulsifier may be 3 parts by mass or more, or 4 parts by mass or more, and 8 parts by mass or less, or 6 parts by mass or less per 100 parts by mass of rubber particles. The content of the emulsifier may be 2 parts by mass or more and 8 parts by mass or less, or 6 parts by mass or less per 100 parts by mass of rubber particles. The content of the emulsifier may be 3 parts by mass or more and 10 parts by mass or less, 8 parts by mass or less, or 6 parts by mass or less per 100 parts by mass of rubber particles. The content of the emulsifier may be 4 parts by mass or more and 10 parts by mass or less, 8 parts by mass or less, or 6 parts by mass or less per 100 parts by mass of rubber particles.

[0033] The water content in the latex may be 30% by mass or more and 85% by mass or less, based on the mass of the latex. The water content may be 40% by mass or more, or 50% by mass or more, and 75% by mass or less, or 70% by mass or less, based on the mass of the latex. The water content may be 30% by mass or more and 75% by mass or less, or 70% by mass or less, based on the mass of the latex. The water content may be 40% by mass or more and 85% by mass or less, 75% by mass or less, or 70% by mass or less, based on the mass of the latex. The water content may be 50% by mass or more and 85% by mass or less, 75% by mass or less, or 70% by mass or less, based on the mass of the latex.

[0034] The latex may further comprise an antioxidant. The antioxidant can be a single compound or a combination of two or more compounds. The antioxidant can be a compound represented by the formula: The antioxidant may contain a compound having one, two, three or four hindered phenol groups. The compound having a hindered phenol group may be represented by formula (1): The compound may be represented by the formula:

[0035] R in formula (1) １ and R ２ are each independently a hydrogen atom or a group represented by the following formula (2a): In formula (2a), R ｎａ represents —O— or NH—, and n １ａ represents an integer of 1 to 20, and n ２ａ represents an integer of 0 to 3. R in formula (1) １ or R ２ At least one of R is a group represented by formula (2a). １ and R ２ When both of the groups are groups represented by formula (2a), they may be the same or different.

[0036] R in formula (1) ３ and R ４ are each independently a hydrogen atom or a group represented by the following formula (2b): In formula (2b), R ｎｂ represents —O— or NH—, and n １ｂ represents an integer of 1 to 20, and n ２ｂ represents an integer of 0 to 3. ３ and R ４ When both of are groups represented by formula (2b), they may be the same or different.

[0037] In formula (1), m represents 0 or 1. When m is 0, the compound represented by formula (1) has the formula: R １ -R ２ It is expressed as:

[0038] n in formula (2a) １ａ can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20. １ａ The range of n can be a range with any two numbers selected from these values ​​as the upper and lower limits. １ａ may be an integer of 1 to 5, 2 to 19, or 15 to 20. ２ａ can be 0, 1, 2, or 3.

[0039] n in formula (2b) １ｂ can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20. １ｂ The range of n can be a range with any two numbers selected from these values ​​as the upper and lower limits. １ｂ may be an integer of 1 to 5, 2 to 19, or 15 to 20. ２ｂ can be 0, 1, 2, or 3, and may be 2.

[0040] R in formula (1) １ and R ２ are both groups represented by formula (2a), and n １ａ may be an integer of 1 to 5. In formula (1), m is 0 and R １ is a hydrogen atom, and R ２is a group represented by formula (2a), and n １ａ may be an integer of 15 to 20.

[0041] The melting point of the antioxidant may be 40° C. or higher and 200° C. or lower. The melting point range of the antioxidant may be a range having an upper and lower limit of two temperatures selected from 45° C., 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., 90° C., 95° C., 100° C., 105° C., 110° C., 115° C., 120° C., 125° C., 130° C., 135° C., 140° C., 145° C., 150° C., 155° C., 160° C., 165° C., 170° C., 175° C., 180° C., 185° C., 190° C., and 195° C. For example, the melting point of the antioxidant may be 45° C. or higher and 170° C. or lower.

[0042] Examples of commercially available antioxidants include Irganox 259, Irganox 1010, Irganox 1076, and Irganox 1098 (all of which are trade names manufactured by BASF Japan), and Adekastab AO-50 and Adekastab AO-60 (all of which are trade names manufactured by ADEKA Corporation).

[0043] The latex may further contain, as a thickening component, a polymer containing (meth)acrylic acid as a monomer unit. "(Meth)acrylic acid" refers to acrylic acid, methacrylic acid, or both. The polymer may contain either acrylic acid or methacrylic acid as a monomer unit, or may contain both of them as monomer units. The molar ratio of monomer units derived from acrylic acid to monomer units derived from methacrylic acid may be 100:0 to 0:100, 10:90 to 90:10, 20:80 to 80:20, or 100:0.

[0044] A polymer containing (meth)acrylic acid as a monomer unit may further contain a monomer other than (meth)acrylic acid as a monomer unit. For example, the polymer may contain a monomer unit derived from one or more monomers selected from α,β-unsaturated carboxylic acids (e.g., crotonic acid, maleic acid, fumaric acid, and itaconic acid), propylene, butene, isobutene, butadiene, isoprene, and styrene.

[0045] Of all the monomer units of the polymer containing (meth)acrylic acid as a monomer unit, the proportion of the monomer units derived from (meth)acrylic acid may be 80 mol% or more, 85 mol% or more, 90 mol% or more, 95 mol% or more, 96 mol% or more, 97 mol% or more, 98 mol% or more, or 99 mol% or more, or may be substantially 100 mol%.

[0046] The polymer containing (meth)acrylic acid as a monomer unit may be a copolymer of (meth)acrylic acid and a compound having two or more ethylenically unsaturated groups (excluding (meth)acrylic acid). This copolymer may be a copolymer (B-1) formed by copolymerization of the following monomer (i) and monomer (ii), a copolymer (B-2) formed by copolymerization of the following monomer (i), monomer (ii) and monomer (iii), or a combination thereof. Monomer (i): (meth)acrylic acid (100 parts by mass) Monomer (ii): compound having two or more ethylenically unsaturated groups (1.0 part by mass or less) Monomer (iii): (meth)acrylic acid alkyl ester having an alkyl group having 10 to 30 carbon atoms (5.0 parts by mass or less)

[0047] The amount of the monomer (ii) may be in the range of 0.05 parts by mass, 0.10 parts by mass, 0.15 parts by mass, 0.20 parts by mass, 0.25 parts by mass, 0.30 parts by mass, 0.35 parts by mass, 0.40 parts by mass, 0.45 parts by mass, 0.50 parts by mass, 0.55 parts by mass, 0.60 parts by mass, 0.65 parts by mass, 0.70 parts by mass, 0.75 parts by mass, 0.80 parts by mass, 0.85 parts by mass, 0.90 parts by mass, 0.95 parts by mass, and 1.0 parts by mass. For example, the amount of the monomer (ii) may be 0.05 parts by mass or more and 1.0 parts by mass or less, or 0.10 parts by mass or more and 0.90 parts by mass or less.

[0048] The amount of the monomer (iii) may be in the range of 0.5 parts by mass, 0.6 parts by mass, 0.7 parts by mass, 0.8 parts by mass, 0.9 parts by mass, 1.0 parts by mass, 1.5 parts by mass, 2.0 parts by mass, 2.5 parts by mass, 3.0 parts by mass, 3.5 parts by mass, 4.0 parts by mass, 4.5 parts by mass, and 5.0 parts by mass. For example, the amount of the monomer (iii) may be 0.5 parts by mass or more and 5.0 parts by mass or less, or 0.60 parts by mass or more and 4.5 parts by mass or less.

[0049] The copolymer (B-1) and the copolymer (B-2) are usually crosslinked polymers crosslinked with a compound having two or more ethylenically unsaturated groups of the monomer (ii).

[0050] Examples of the compound having two or more ethylenically unsaturated groups as the monomer (ii) include (meth)acrylic acid esters of polyols, allyl ethers of polyols, diallyl phthalate, triallyl phosphate, allyl methacrylate, tetraallyloxyethane, triallyl cyanurate, divinyl adipate, vinyl crotonate, 1,5-hexadiene, and divinylbenzene.

[0051] Examples of polyols from which the (meth)acrylic acid ester or allyl ether is derived include ethylene glycol, propylene glycol, polyoxyethylene glycol, polyoxypropylene glycol, glycerin, polyglycerin, trimethylolpropane, pentaerythritol, sucrose, and sorbitol.

[0052] Monomer (ii) may be one or more selected from sucrose allyl ether, pentaerythritol allyl ether (e.g., pentaerythritol triallyl ether, pentaerythritol tetraallyl ether), tetraallyloxyethane, triallyl phosphate, and polyallylsucrose. Monomer (ii) may be sucrose allyl ether, pentaerythritol allyl ether, or a combination thereof.

[0053] The compounds having two or more ethylenically unsaturated groups exemplified above can be used either alone or in combination of two or more.

[0054] The (meth)acrylic acid alkyl ester of monomer (iii) is an ester of (meth)acrylic acid and an alkyl alcohol having 10 to 30 carbon atoms. The number of carbon atoms in the alkyl group of this (meth)acrylic acid alkyl ester can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30. The number of carbon atoms in the alkyl group of the (meth)acrylic acid alkyl ester may also be 12 to 30, 14 to 28, 16 to 26, or 18 to 24.

[0055] Examples of the (meth)acrylic acid alkyl ester of the monomer (iii) include stearyl (meth)acrylate, eicosanyl (meth)acrylate, behenyl (meth)acrylate, and (meth)acrylic acid and tetracosanyl. These (meth)acrylic acid alkyl esters can be used alone or in combination of two or more. Examples of commercially available (meth)acrylic acid alkyl esters include the trade names Blemmer VMA70 and Blemmer SMA manufactured by Nippon Oil & Fats Corporation.

[0056] The polymerization method for obtaining the copolymer (B-1) or the copolymer (B-2) is not particularly limited, and may be, for example, a method including polymerizing a monomer in a polymerization solvent in the presence of a radical polymerization initiator.

[0057] Examples of the radical polymerization initiator include α,α'-azobisisobutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 2,2'-azobismethylisobutyrate, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, and tert-butyl hydroperoxide. These radical polymerization initiators can be used alone or in combination of two or more.

[0058] The amount of the radical polymerization initiator may be, for example, 0.01 parts by mass or more and 0.45 parts by mass or less, or 0.01 parts by mass or more and 0.35 parts by mass or less, relative to 100 parts by mass of (meth)acrylic acid.

[0059] The polymerization method for obtaining the copolymer (B-1) or the copolymer (B-2) may be precipitation polymerization or reversed-phase suspension polymerization. In the case of reversed-phase suspension polymerization, the polymerization solvent may contain one or more nonionic surfactants having a polyoxyethylene chain.

[0060] The nonionic surfactant having a polyoxyethylene chain may be, for example, a polyhydric alcohol fatty acid ester ethylene oxide adduct, a block copolymer of a hydroxy fatty acid and ethylene oxide, polyoxyethylene castor oil, or a combination thereof.

[0061] Examples of polyhydric alcohol fatty acid ester ethylene oxide adducts include ester compounds of polyoxyethylene hydrogenated castor oil and fatty acids. The fatty acids here may be saturated or unsaturated fatty acids having 14 to 24 carbon atoms. The number of carbon atoms of the fatty acids here may be 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24. Examples of fatty acids having 14 to 24 carbon atoms include isopalmitic acid, isostearic acid, and isooleic acid. In the ester compounds of polyoxyethylene hydrogenated castor oil and fatty acids, the average number of moles of ethylene oxide added to the polyoxyethylene may be, for example, 20 to 100, 30 to 70, 2 to 10, or 2 to 5. The ester compounds of polyoxyethylene hydrogenated castor oil and fatty acids may be polyoxyethylene hydrogenated castor oil isostearate.

[0062] In other words, a block copolymer of a hydroxy fatty acid and ethylene oxide is a copolymer of a poly(hydroxy fatty acid) and poly(oxyethylene). The hydroxy fatty acid may have 14 to 22 carbon atoms. Examples of the hydroxy fatty acid include hydroxymyristic acid, hydroxypalmitic acid, and hydroxystearic acid. The hydroxy fatty acid may be hydroxystearic acid (e.g., 12-hydroxystearic acid). In other words, the block copolymer of a hydroxy fatty acid and ethylene oxide may be a block copolymer of 12-hydroxystearic acid and ethylene oxide.

[0063] The amount of the nonionic surfactant having a polyoxyethylene chain may be 0.5 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of (meth)acrylic acid. The amount of the nonionic surfactant having a polyoxyethylene chain may be 0.75 parts by mass or more, 1.0 parts by mass or more, 1.25 parts by mass or more, or 1.5 parts by mass or more relative to 100 parts by mass of (meth)acrylic acid, and may be 9.5 parts by mass or less, 9.0 parts by mass or less, 8.5 parts by mass or less, 8.0 parts by mass or less, 7.5 parts by mass or less, 7.0 parts by mass or less, 6.5 parts by mass or less, 6.0 parts by mass or less, or 5.5 parts by mass or less. For example, the amount of the nonionic surfactant having a polyoxyethylene chain may be 1.0 parts by mass or more and 7.5 parts by mass or less relative to 100 parts by mass of (meth)acrylic acid.

[0064] Examples of polymerization solvents for the polymerization reaction to obtain copolymer (B-1) or copolymer (B-2) include normal pentane, normal hexane, normal heptane, normal octane, isooctane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, chlorobenzene, ethylene dichloride, ethyl acetate, isopropyl acetate, ethyl methyl ketone, and isobutyl methyl ketone. The polymerization solvent may be ethylene dichloride, normal hexane, normal heptane, ethyl acetate, or a combination thereof. These polymerization solvents may be used alone or in combination of two or more.

[0065] The amount of the polymerization solvent may be, for example, 200 parts by mass or more and 10,000 parts by mass or less, or 300 parts by mass or more and 2,000 parts by mass or less, relative to 100 parts by mass of (meth)acrylic acid.

[0066] The polymerization reaction may be carried out in an inert gas atmosphere such as nitrogen gas or argon gas. The reaction temperature of the polymerization reaction may be, for example, 50°C or higher and 90°C or lower, or 55°C or higher and 75°C or lower. The reaction time of the polymerization reaction is usually about 2 hours or higher and 10 hours or lower. After the polymerization reaction, the polymerization solvent can be removed to obtain a white fine powder containing the copolymer.

[0067] The storage modulus G' of an aqueous solution containing a polymer containing (meth)acrylic acid as a monomer unit at an angular frequency of 0.1 rad / s may be 10 Pa or more and 1000 Pa or less. The storage modulus G' is a value determined based on frequency dispersion in an angular frequency range of 0.1 rad / s or more and 300 rad / s or less, obtained under the following measurement conditions. The frequency dispersion can be measured using a rheometer (for example, TA Instruments (model number: AR 2000ex)). Measurement conditions: Sample: Neutralized aqueous solution containing a polymer containing (meth)acrylic acid as a monomer unit at a concentration of 1.0 mass % and having a degree of neutralization of 70% Sample temperature: 25°C Frequency: 1 Hz Strain in strain dispersion: 0.1% or 1%

[0068] The neutralized aqueous solution for measuring the storage modulus can be prepared, for example, by a method comprising preparing an aqueous dispersion containing an appropriate amount of the polymer, adding an aqueous alkali (e.g., NaOH) solution of an appropriate concentration to the aqueous dispersion to neutralize 70% of the carboxyl groups in the polymer, and adding additional water as necessary. The degree of neutralization is the proportion of neutralized carboxyl groups among the carboxyl groups in the copolymer.

[0069] The storage modulus G' of an aqueous solution containing a polymer containing (meth)acrylic acid as a monomer unit at an angular frequency of 0.1 rad / s was 20 Pa, 30 Pa, 40 Pa, 50 Pa, 60 Pa, 70 Pa, 80 Pa, 90 Pa, 100 Pa, 110 Pa, 120 Pa, 130 Pa, 140 Pa, 150 Pa, 160 Pa, 170 Pa, 180 Pa, 190 Pa, 200 Pa, 210 Pa, 220 Pa, 230 Pa, 240 Pa, 250 Pa, 260 Pa, 270 Pa, 280 Pa, 290 Pa, 300 Pa, 310 Pa, 320 Pa, 330 Pa, 340 Pa, 350 Pa, 360 Pa, 370 Pa, 380 Pa, 390 Pa, 400 Pa, 410 Pa, 420 Pa, 430 Pa, 440 Pa, 450 Pa, 460 Pa, 470 Pa, 480 Pa, 490 Pa, 500 Pa, 510 Pa, 520 Pa, 530 Pa, 540 Pa, 550 Pa, 560 Pa, 570 Pa, 580 Pa, 590 Pa, 600 Pa, 610 Pa, 620 Pa, 630 Pa, 640 Pa, 650 Pa, 660 Pa, 670 Pa, 680 Pa, 690 Pa, 700 Pa, 710 Pa, 720 Pa, 730 Pa, 740 Pa, 750 Pa, 760 Pa, 770 Pa, 780 Pa, 790 Pa, 800 Pa, 810 Pa, 20Pa, 230Pa, 240Pa, 250Pa, 260Pa, 270Pa, 280Pa, 290Pa, 300Pa, 310Pa, 320Pa, 330Pa, 340Pa, 350Pa, 360Pa, 370Pa, 380Pa, 390Pa, 400Pa, 410Pa, 420Pa, 430Pa, 440Pa, 450Pa, 460Pa, 470Pa, 480Pa, 490Pa, 500Pa, 510Pa, 520Pa, 530Pa, 540Pa, 550Pa, 560Pa, 570Pa, 580Pa, 590Pa, 600Pa, 610Pa, 620Pa, 630Pa , 640Pa, 650Pa, 660Pa, 670Pa, 680Pa, 690Pa, 700Pa, 710Pa, 720Pa, 730Pa, 740Pa, 750Pa, 760Pa, 770Pa , 780 Pa, 790 Pa, 800 Pa, 810 Pa, 820 Pa, 830 Pa, 840 Pa, 850 Pa, 860 Pa, 870 Pa, 880 Pa, 890 Pa, 900 Pa, 910 Pa, 920 Pa, 930 Pa, 940 Pa, 950 Pa, 960 Pa, 970 Pa, 980 Pa, and 990 Pa. For example, the storage modulus G' may be 20 Pa or more and 900 Pa or less, or 30 Pa or more and 800 Pa or less.

[0070] The latex may further include a thickening component such as polyoxyethylene styrenated phenyl ether.

[0071] In the polyoxyethylene styrenated phenyl ether, the number of moles of ethylene oxide (EO) added may be 3 to 20. The number of moles of ethylene oxide (EO) added may be 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20. The polyoxyethylene styrenated phenyl ether is represented, for example, by the following formula: In the formula, m represents 1 or 2, and n represents 3 to 20. m may be 2. The polyoxyethylene styrenated phenyl ether may be one type alone or a combination of two or more types.

[0072] The latex can be produced, for example, by a method including: preparing a rubber solution containing EBDM, an emulsifier precursor, and an organic solvent, with the EBDM and the emulsifier precursor dissolved in the organic solvent; adding an aqueous solution containing a compound that neutralizes the emulsifier precursor to form an emulsifier to the rubber solution to form an emulsion containing rubber particles and the emulsifier; and removing the organic solvent from the emulsion. The emulsifier precursor may be an organic acid compound such as a carboxylic acid or a sulfonic acid (e.g., oleic acid). The compound that neutralizes the emulsifier precursor may be an alkali metal compound (e.g., potassium hydroxide). The organic solvent is removed from the emulsion to form a latex. The formed latex may be concentrated by membrane separation, centrifugation, or the like.

[0073] Alternatively, the latex can be produced by a process comprising providing a rubber solution containing EBDM and an organic solvent, the EBDM dissolved in the organic solvent, adding an aqueous solution containing an emulsifier to the rubber solution to form an emulsion containing rubber particles and the emulsifier, and removing the organic solvent from the emulsion. Again, the latex formed by removal of the organic solvent may be concentrated.

[0074] (Adhesive) Latex containing EBDM alone or a mixture of this with other materials can be used as an adhesive. For example, a mixture of RFL (resorcinol-formalin-latex) and latex containing EBDM may be used as an adhesive. An adhesive using latex containing EBDM can be used, for example, to bond steel cords and rubber in automobile tires.

[0075] The latex containing the EBDM according to the present disclosure (hereinafter sometimes referred to as "EBDM latex") can be used as a latex component of adhesives such as RFL adhesives, binder materials for various plastics, coating materials, fiber treatment agents, etc. These materials containing EBDM latex can be used to produce various molded products such as automotive timing belts or brake hoses, paint films, window frames, and fiber-reinforced composite materials.

[0076] RFL adhesives containing EBDM latex as a latex component may contain additives such as thickeners (e.g., the above-mentioned thickening components), tackifiers, plasticizers, and stabilizers to improve application properties or stability and increase adhesive strength. Such additives may be added to the RFL adhesive after preparation, or may be added to the EBDM latex in advance. Depending on the type of additive, it may also be added to an organic solvent or aqueous solution during the preparation of the EBDM latex. The additives may be added individually or as a mixture in the form of an aqueous solution or dispersion.

[0077] The EBDM content in an RFL adhesive containing EBDM latex as a latex component may be 10% by mass or more, 20% by mass or more, or 30% by mass or more, and 99% by mass or less, 95% by mass or less, or 90% by mass or less, based on the amount of solids in the RFL adhesive. The EBDM content in the RFL adhesive may be 10% by mass or more and 99% by mass or less, 95% by mass or less, or 90% by mass or less, based on the amount of solids in the RFL adhesive. The EBDM content in the RFL adhesive may be 20% by mass or more and 99% by mass or less, 95% by mass or less, or 90% by mass or less, based on the amount of solids in the RFL adhesive. The EBDM content in the RFL adhesive may be 30% by mass or more and 99% by mass or less, 95% by mass or less, or 90% by mass or less, based on the amount of solids in the RFL adhesive.

[0078] (Rubber Reinforcing Cord) Using EBDM latex, a rubber reinforcing cord having fibers and a coating provided on the outer surface of the fibers can be produced. The coating of the rubber reinforcing cord is formed from latex. The coating is provided so as to cover part or all of the outer surface of the fibers.

[0079] A method for producing a rubber-reinforcing cord includes, for example, preparing a treating agent containing latex and a resin (e.g., the above-mentioned RFL) that is a condensate of a compound having a phenolic hydroxyl group and formaldehyde, applying the treating agent to the outer surface of a fiber, and removing water from the treating agent on the outer surface of the fiber to form a coating that covers at least a portion of the outer surface of the fiber. The treating agent may be the above-mentioned RFL adhesive.

[0080] Examples of fibers that may be used to form the rubber reinforcing cord include glass fibers, polyvinyl alcohol fibers (e.g., vinylon fibers), polyester fibers, polyamide fibers (e.g., Nylon (registered trademark), aromatic polyamides), polyarylate fibers, polyketone fibers, carbon fibers, and polyparaphenylenebenzoxazole (PBO) fibers.

[0081] The rubber reinforcing cord is used, for example, to produce a rubber molded article including a matrix rubber and the rubber reinforcing cord embedded in the matrix rubber. A method for producing the rubber molded article includes, for example, embedding the rubber reinforcing cord in a matrix rubber containing rubber and a crosslinking agent, and crosslinking the rubber by a reaction with the crosslinking agent. The reaction between the rubber and the crosslinking agent can be promoted by heating. The heating that crosslinks the rubber in the matrix rubber may also crosslink the rubber (EBDM) in the coating of the rubber reinforcing cord.

[0082] A rubber molded article reinforced with a rubber reinforcing cord can be used, for example, as a component of a timing belt for a vehicle engine.

[0083] (Waterproof Layer) The EBDM latex can be used to form a waterproof layer. For example, a waterproof layer containing EBDM and constituting the surface layer of the porous member can be formed by penetrating a primer containing latex into the surface layer of the porous member.

[0084] The porous member on which the waterproof layer is formed may be a concrete member. In this case, the waterproof layer may be formed by a method including, for example, laying a waterproof sheet having openings on the surface of the concrete member and impregnating the surface layer of the concrete member exposed through the openings in the waterproof sheet with a primer (latex) to form a primer-impregnated layer. An adhesive layer, a metal disk, and a thermoplastic resin layer may be laminated in this order on the primer-impregnated layer, and the waterproof sheet for renovation may be fused to the thermoplastic resin layer.

[0085] (Improvement of physical properties by fiber material) By mixing one or more fiber materials with latex, various physical properties such as various strengths including tensile strength can be improved for rubber materials containing EBDM. Various rubber molded products can be produced by a conventional method using the rubber material containing a fiber material.

[0086] The rubber material containing EBDM and a fibrous material can be produced, for example, by a method including mixing a fibrous material with latex to form a rubber latex composition containing EBDM, a fibrous material, and water, removing water from the rubber latex composition to form a masterbatch, and kneading a mixture containing the masterbatch and a vulcanizing agent to form a rubber material containing EBDM and a fibrous material dispersed in the EBDM.

[0087] The rubber material may include two or more types of fibrous materials. An example of a method for producing a rubber material including two types of fibrous materials includes mixing a first fibrous material with a latex to form a first rubber latex composition including EBDM, the first fibrous material, and water, removing water from the first rubber latex composition to form a first masterbatch, mixing a second fibrous material with the latex to form a second rubber latex composition including EBDM, the second fibrous material, and water, removing water from the second rubber latex composition to form a second masterbatch, and kneading a mixture including the first masterbatch, the second masterbatch, and a vulcanizing agent to form a rubber material including EBDM and the first and second fibrous materials dispersed in the EBDM.

[0088] The fibrous material may be, for example, a nanofiber, in particular a cellulose nanofiber, or a biomass nanofiber.

[0089] The vulcanizing agent used to form the rubber material can be, for example, a sulfur-based vulcanizing agent, an organic peroxide, or a combination thereof. Examples of sulfur-based vulcanizing agents include sulfur and morpholine disulfide. Examples of organic peroxides include dicumyl peroxide, t-butylperoxybenzene, and di-t-butylperoxy-diisopropylbenzene. These vulcanizing agents can be used alone or in combination of two or more.

[0090] A vulcanization accelerator, a vulcanization aid, and the like may be added to the kneaded mixture together with the vulcanizing agent.

[0091] (Rubber Film Products) Latex containing EBDM alone or a mixture thereof with other materials can be used to produce rubber film products, which are molded articles having a thin film containing rubber. Examples of rubber film products include artificial nipples, balloons, gloves, finger cots, and films. The thickness of the thin film containing rubber may be, for example, 0.01 mm or more and 10 mm or less, 2 mm or less, or 0.03 mm or more and 10 mm or less, 2 mm or less, or 1 mm or less.

[0092] Other materials to be combined with the latex containing EBDM can be, for example, one or more selected from natural rubber latex, synthetic rubber latex, agents for crosslinking polymers, surfactants, dispersants, wetting agents, antifoaming agents, pH adjusters, preservatives, antioxidants, and fillers. A mixture for producing a rubber coating product can be obtained, for example, by mixing the latex and other materials using any stirrer or mixer.

[0093] A molded article (rubber film product) having a thin rubber film can be produced, for example, by a method including: preparing a rubber latex composition containing EBDM alone or a mixture of EBDM and other materials; forming a molding material by removing water from the rubber latex composition using a coagulant or by heating; and molding the molding material into a thin film using a molding machine such as a press. Alternatively, a rubber film product can be obtained by a method including preparing a rubber latex composition containing EBDM alone or a mixture of EBDM and other materials; applying the rubber latex composition to the surface of a mold to form a thin film of the rubber latex composition; and removing water from the thin film of the rubber latex composition. A coagulant may be used to form the thin film of the rubber latex composition.

[0094] The present invention is not limited to the following examples.

[0095] 1. Preparation of Latex Example 1 528 g (100 parts by mass) of ethylene-1-butene-5-ethylidene-2-norbornene copolymer (Mitsui Chemicals, Inc., trade name "EBT") as EBDM and 3,872 g (733 parts by mass) of toluene were placed in a separable flask. The EBDM was dissolved in toluene with stirring at 70°C for 6 hours to prepare a rubber solution. The concentration of EBDM (rubber) was 12 mass% based on the mass of the rubber solution. 26.4 g (5 parts by mass) of oleic acid was dissolved in the obtained rubber solution.

[0096] An aqueous potassium hydroxide solution was prepared by dissolving 5.2 g (1.0 part by mass) of potassium hydroxide in 1,967 g of water. The mass ratio (organic layer / aqueous layer, hereinafter referred to as "PR") of the organic layer (rubber solution containing dissolved oleic acid) to the aqueous layer (aqueous potassium hydroxide solution) was 2.2. The amount of potassium hydroxide was 1 molar amount relative to the amount of oleic acid in the rubber solution.

[0097] The aqueous potassium hydroxide solution was added to the rubber solution in the separable flask, and the mixture was stirred for 43 minutes using a mixer (TK Auto Homomixer SL Type, manufactured by Primix Corporation) to form an emulsion containing potassium oleate as an emulsifier. The stirring speed was set at 9,000 rpm. Assuming that all of the oleic acid formed potassium oleate, the amount of potassium oleate used as an emulsifier was 6 parts by mass per 100 parts by mass of EBDM (rubber).

[0098] The resulting emulsion was heated to 55°C under a reduced pressure of 20 kPa to remove toluene and form a latex containing rubber particles containing EBDM. The formed latex was concentrated to a solids concentration of 40% by mass using an ultrafilter (ultrafiltration membrane: flat membrane type, molecular weight cutoff: 200,000, material: polysulfone). The solids concentration in the latex was determined by removing water from a latex sample by heating at 130°C for 2 hours and measuring the mass of the residue, and essentially corresponds to the concentration of rubber particles based on the mass of the latex.

[0099] Examples 2 to 16 Latices were obtained in the same manner as in Example 1, except that the solids concentration of the rubber solution, the type and amount of emulsifier, and the mass ratio (PR) of the organic layer to the aqueous layer were changed as shown in Table 1. However, except for Examples 1 and 5, concentration using an ultrafilter was not performed. In Example 1, oleic acid and potassium hydroxide (KOH) were prepared separately and brought into contact with each other in the emulsifying step as described above to form potassium oleate as an emulsifier, but in Examples 5 to 16, the entire amount of the emulsifier listed in Table 1 was dissolved or dispersed in water.

[0100] Details of the emulsifiers indicated by trade names in Table 1 are as follows: The amount of emulsifier shown in Table 1 is the amount of solids excluding solvents and the like from each emulsifier, and is expressed in parts by mass (phr) per 100 parts by mass (phr) of EBDM. Rapisol A-80: trade name, manufactured by NOF Corporation, solid content 80% by mass, sodium di-2-ethylhexyl sulfosuccinate Newlex R: trade name, manufactured by NOF Corporation, solid content 50% by mass, sodium alkyl (C10-16) benzenesulfonate Diapon S: trade name, manufactured by NOF Corporation, solid content 13% by mass, sodium fatty acid methyl taurate Nissan Anon BL: trade name, manufactured by NOF Corporation, solid content 35% by mass, lauryl dimethylaminoacetate betaine Longis K-25: trade name, manufactured by Arakawa Chemical Co., Ltd., solid content 25% by mass, potassium rosinate Persoft EF: trade name, manufactured by NOF Corporation, solid content 25% by mass, sodium polyoxyethylene lauryl ether sulfate DKS Discoat N-14: trade name, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., solid content 30% by mass, styrene-maleic acid copolymer half ester ammonium salt Softilt AS-L: trade name, manufactured by NOF Corporation, solid content 30% by mass, N-lauroylmethylalanine sodium Demol N: trade name, manufactured by Kao Corporation, solid content 100%, β-naphthalenesulfonic acid formalin condensate sodium salt Newcol 240: trade name, manufactured by Nippon Nyukazai Co., Ltd., solid content 30% by mass, polyoxyalkylene disulfonate sodium

[0101] Comparative Example 1 450 g (100 parts by mass) of chlorosulfonated polyethylene (CSM) (product name "TOSO-CSM TS-320" by Tosoh Corporation) and 2,550 g (567 parts by mass) of toluene were placed in a separable flask. The CSM was dissolved in toluene by stirring at 70°C for 8 hours to prepare a rubber solution. The concentration of CSM (rubber) was 15 wt% based on the mass of the rubber solution. 4.7 g (1.0 mass) of oleic acid was dissolved in the obtained rubber solution.

[0102] An aqueous layer containing an emulsifier was prepared by dissolving or dispersing 1.9 g (0.42 parts by mass) of potassium hydroxide, 39.0 g (2.6 parts by mass) of sodium polyoxyalkylene alkyl ether sulfate (trade name "Trax ET-314" by NOF Corporation), and 28.1 g (1.6 phr) of sodium polyoxyethylene alkyl ether sulfate (trade name "Persoft EF" by NOF Corporation) in 1,724 g of water. The amount of water was such that the PR was 1.7. The amount of potassium hydroxide was such that the molar ratio was twice the amount of oleic acid in the rubber solution.

[0103] The aqueous solution containing the emulsifier was added to the rubber solution in the separable flask, and the mixture was stirred and mixed for 32 minutes using a stirrer (TK Auto Homomixer SL type, manufactured by Primix Corporation) to form an emulsion containing potassium oleate, sodium polyoxyalkylene alkyl ether sulfate, and sodium polyoxyethylene alkyl ether sulfate as emulsifiers. The stirring speed was set to 9,000 rpm.

[0104] The obtained emulsion was heated to 55°C under a reduced pressure of 20 kPa to distill off the toluene, thereby forming a latex containing rubber particles containing CSM. The formed latex was concentrated to a solids concentration of 40% by mass using an ultrafiltration device (ultrafiltration membrane: flat membrane type, molecular weight cutoff: 200,000, material: polysulfone).

[0105] 2. Evaluation Median diameter of rubber particles The particle diameters of rubber particles in the latex before and immediately after concentration were measured using a laser diffraction particle size distribution analyzer (Shimadzu Corporation, trade name "SALD-2300"). From the patterns of diffraction and scattered light, the particle diameter was determined when the particle shape was considered to be a perfect sphere, and the particle size distribution was calculated based on the volume of a perfect sphere having that particle diameter. From the particle size distribution, the volume-based median diameter was determined. The median diameters of rubber particles before concentration are shown in Table 1. The median diameters of rubber particles immediately after concentration are shown in Table 2.

[0106]

[0107] Change in pH over time The concentrated latexes of Example 1 and Comparative Example 1 were allowed to stand at about 25°C for 14 days. The median diameter of rubber particles and pH of the latexes immediately after concentration and after standing for 14 days were measured. The measurement results are shown in Table 2. The latexes of the examples showed a stable pH for a long time. The median diameter of rubber particles was also sufficiently stable.

[0108]

Claims

1. A latex comprising: rubber particles containing an ethylene-butene-diene copolymer; an emulsifier; and water.

2. The latex according to claim 1, wherein the content of the rubber particles is 15% by mass or more and 70% by mass or less based on the mass of the latex, and the content of the emulsifier is 2 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the rubber particles.

3. The latex according to claim 1 or 2, wherein, based on the total mass of said ethylene-butene-diene copolymer, the ratio of monomer units derived from ethylene is 40% by mass or more and 80% by mass or less, the ratio of monomer units derived from butene is 5% by mass or more and 58% by mass or less, and the ratio of monomer units derived from diene is 2% by mass or more and 15% by mass or less.

Images