JP2014231608A - Aqueous adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing a copolymer latex for aqueous adhesives which is excellent in contact adhesiveness immediately after lamination, heat-resistant creep properties and adhesive strength after curing and a latex obtained by the production method.SOLUTION: A method of producing a copolymer latex for aqueous adhesives by emulsion polymerization comprises emulsion-polymerizing monomers containing a conjugated diene monomer in two steps: a first-polymerization-step monomer is polymerized by using a specified amount of a chain-transfer agent; and, when the polymerization conversion rate reaches 75% or higher, a second-polymerization-step monomer and a specified amount of chain-transfer agent are added and the resultant mixture is polymerized. The copolymer latex for aqueous adhesives obtained by the production method is also provided.

Description

  INDUSTRIAL APPLICABILITY The present invention can be used in industrial fields such as residential building materials, woodworking furniture, fields for architectural interiors used at construction sites, and application fields for solvent-based adhesives widely used in general households. A water-based adhesive that does not harm the environment and health because it does not contain organic solvents, has no danger of fire, etc., has excellent contact adhesion immediately after bonding, and has excellent heat creep resistance and adhesive strength after curing. Copolymer latex for use.

Solvent-based adhesives containing a large amount of solvent are used in a wide range of fields for reasons such as good adhesion, high drying speed, and ease of work. However, many of the solvents contained in these adhesives are toxic and there is a risk of polluting the environment, so the development of water-based adhesives that do not contain solvents is being promoted. Agent substitution is being actively carried out. This solvent-based chloroprene adhesive has features such as good adhesive strength (contact adhesiveness) immediately after drying and pasting, strong adhesive strength after curing, and good heat-resistant creep properties. . For example, chloroprene rubber is emulsified as a water-based solvent-based chloroprene adhesive, and many prior arts are disclosed. For example, a method (Patent Document 1) in which chloroprene and an ethylenically unsaturated carboxylic acid are emulsion-polymerized using a vinyl alcohol copolymer as a dispersant has been proposed. As for the diene copolymer latex, there is no description about contact adhesiveness or heat-resistant creep, but a prior art that defines a method of using a chain transfer agent has been proposed as a latex having excellent adhesive strength. For example, a method of continuing the addition of the chain transfer agent even after the addition of the monomer to the polymerization system (Patent Document 2) and a method of adding another chain transfer agent after the completion of the monomer addition (Patent Document 3) have been proposed. Yes. In addition, in the two-stage polymerization in which the total amount of the conjugated diene monomer is blended in the first polymerization stage, a method for specifying the amount of chain transfer agent used in the first polymerization stage and the second polymerization stage has been proposed (Patent Document 4). Yes.
JP 2004-346183 A JP-A-4-41511 Special table 2006-526681 JP 57-153012 A

  However, from the viewpoint of realizing a water-based adhesive that balances contact adhesiveness, heat-resistant creep resistance, and post-curing adhesive strength in a balanced manner, the actual situation is that a sufficiently satisfactory one has not yet been obtained. In addition, no proposals have been made regarding the improvement of contact adhesiveness and heat-resistant creep resistance with respect to proposals for adding chain transfer agents to many diene latexes.

  An object of the present invention is to provide a copolymer latex for an aqueous adhesive that is excellent in contact adhesiveness immediately after bonding and excellent in heat-resistant creep resistance and adhesive strength after curing.

  As a result of diligent studies to solve the above-mentioned problems, the present inventors have divided the monomer containing a conjugated diene monomer as an essential component into two stages when producing a copolymer latex by emulsion polymerization. The first polymerization stage monomer is polymerized using a specific amount of chain transfer agent until a specific polymerization conversion is reached, and then the second polymerization stage monomer and a specific amount of chain transfer agent are used. It was found that the object can be achieved by adding and polymerizing, and the present invention has been completed based on this finding.

  That is, the present invention provides the following method for producing a copolymer latex for aqueous adhesive and a copolymer latex for aqueous adhesive.

(1) 30 to 70% by mass of conjugated diene monomer, 0.1 to 15% by mass of ethylenically unsaturated carboxylic acid monomer, and 15 to 69.9% of other monomers copolymerizable therewith %, A method for producing a copolymer latex for an aqueous adhesive comprising emulsion polymerization of
First polymerization in which 30 to 90% by mass of all monomers including 1 to 69% by mass of the conjugated diene monomer is polymerized by adding the first chain transfer agent, and the polymerization conversion rate is 75% or more. A second polymerization stage in which the polymerization is continued by adding 10 to 70% by mass of the total monomer including 1 to 69% by mass of the conjugated diene monomer and a second chain transfer agent;
A part by mass of the first chain transfer agent relative to 100 parts by mass of the monomer in the first polymerization stage, and a part by mass of the second chain transfer agent relative to 100 parts by mass of the monomer in the second polymerization stage. Is b, a and b are represented by the following formula (I):
0.1 ≦ a ≦ 5
0.2 ≦ b ≦ 10 (I)
b> a
The method as described above, characterized in that:

(2) The chain transfer agent is a chain transfer agent selected from mercaptans or a combination of a chain transfer agent selected from mercaptans and other chain transfer agents, and used in the first polymerization stage. Selected from mercaptans contained in the chain transfer agent used in the second polymerization stage, and a mass part x of 100 parts by mass of the monomer in the first polymerization stage of the chain transfer agent selected from mercaptans contained in the agent. Mass part y with respect to 100 parts by mass of the monomer in the second polymerization stage of the chain transfer agent is represented by the following formula (II):
0.1 ≦ x ≦ 5
0.2 ≦ y ≦ 10 (II)
y> x
The method according to (1), wherein

(3) In the second polymerization stage, the gel fraction (m) of the copolymer in the first polymerization stage at the start of addition of the monomer and the second chain transfer agent in the second polymerization stage is 35. The method according to (1) or (2), which is -80%.

(4) The gel fraction (n) of the finally obtained copolymer latex is 40 to 90%, and the gel fraction (m) of the copolymer in the first polymerization stage is
0.8 ≦ (n) / (m) ≦ 1.25
The method according to (3), wherein

(5) A copolymer latex for aqueous adhesive that can be produced by the method according to any one of (1) to (4).

  By using the copolymer latex of the present invention, it is possible to realize an aqueous adhesive that is excellent in contact adhesion immediately after bonding, and excellent in heat-resistant creep resistance and adhesive strength. The solvent-type adhesive can be replaced with the copolymer latex of the present invention, and problems such as environmental pollution caused by organic solvents can be avoided.

  The best mode for carrying out the present invention (hereinafter, an embodiment of the present invention) will be described in detail below. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

  In the embodiment of the present invention, the composition of the monomer constituting the copolymer latex is 30 to 70% by mass of the conjugated diene monomer and 0.1 to 15% by mass of the ethylenically unsaturated carboxylic acid monomer. And 15 to 69.9% by mass of other monomers copolymerizable therewith.

  When these monomers are added in two stages and emulsion polymerization is carried out to produce a copolymer latex, the monomer in the first polymerization stage (hereinafter also referred to as the first polymerization stage monomer) is conjugated. A monomer composed of 1 to 69% by mass of a diene monomer and another monomer appropriately selected, and 30 to 90% by mass of the total monomer, a first chain transfer agent a mass Part (a is a mass part with respect to 100 parts by mass of the first polymerization stage monomer) and polymerized, and after the polymerization conversion rate becomes 75% or more, the monomer in the second polymerization stage (hereinafter referred to as the second polymerization stage). It is also composed of 1 to 69% by mass of a conjugated diene monomer as the polymerization stage monomer) and 10 to 70% by mass of the total monomer and the second chain. A transfer agent b parts by mass (b is a part by mass with respect to 100 parts by mass of the second polymerization stage monomer) is added for polymerization.

  The monomers other than the conjugated diene system in the first polymerization stage monomer and the second polymerization stage monomer are not particularly limited, and one or more kinds may be appropriately selected.

  The addition method of the first polymerization stage monomer and the second polymerization stage monomer to the polymerization system may be a batch addition method, a method of adding continuously or intermittently, or a method combining these methods (for example, a simple method). Any method may be used in which a part of the monomer is added and then the remaining monomer is added continuously or intermittently as the polymerization proceeds.

  The start of addition of the second polymerization stage monomer and the second chain transfer agent in the second polymerization stage is after the polymerization conversion rate of the first polymerization stage monomer reaches usually 75% or more, preferably 80% or more. It is necessary to be. If it is less than 75%, it is not possible to obtain a copolymer latex which is the object of the present invention and has excellent contact adhesion immediately after bonding and excellent heat-resistant creep resistance.

  Examples of the conjugated diene monomer used in the present invention include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, and 2-methyl-1. , 3-butadiene, 1,3-pentadiene, chloroprene, 2-chloro-1,3-butadiene, cyclobutadiene and the like, and these can be used alone or in combination of two or more. Among these, 1,3-butadiene can be preferably used.

  The ratio of the conjugated diene monomer to the total amount of all monomers, that is, the first and second polymerization stage monomers, is usually 30 to 70% by mass, preferably 35 to 65% by mass. Further, the conjugated diene monomer contained in the first polymerization stage monomer and the second polymerization stage monomer is usually 1 to 69% by mass, preferably 5 to 60% by mass as a proportion of the total polymerization monomers. %. By setting the conjugated diene monomer within the above range, the copolymer latex can be imparted with appropriate flexibility and toughness, and heat resistant creep resistance and adhesive strength can be improved.

  In the polymerization of the first polymerization stage monomer, the chain transfer agent in the present invention is added with 1 part by mass of the first chain transfer agent (part by mass with respect to 100 parts by mass of the first polymerization stage monomer), and the polymerization rate is After 75% or more, the second polymerization stage monomer and b parts by mass of the second chain transfer agent (parts by mass with respect to 100 parts by mass of the second polymerization stage monomer) are added. It must be within the range represented by> a. The mass part a is usually 0.1 ≦ a ≦ 5, preferably 0.3 ≦ a ≦ 4, more preferably 0.5 ≦ a ≦ 3, and the mass part b is usually 0.2 ≦ b ≦ 3. 10, preferably 1 ≦ b ≦ 7, more preferably 2 ≦ b ≦ 6.

  If the mass part a of the first chain transfer agent and the mass part b of the second chain transfer agent do not satisfy this range, the copolymer latex is excellent in contact adhesion immediately after bonding and excellent in heat-resistant creep resistance. Can't get. In particular, it is important that b is larger than a, and by increasing the amount of the second chain transfer agent added in the second polymerization stage and reducing the gel fraction, the contact adhesion immediately after bonding is excellent. In addition, it is possible to realize a water-based adhesive having excellent heat resistance creep resistance.

  As a method for adding a chain transfer agent, for example, a method of adding a mixture with a monomer, a method of adding a chain transfer agent alone, a method of adding a chain transfer agent continuously or intermittently, a batch of chain transfer agents Although the method of adding etc. is mentioned, if the range which said a and b prescribe is satisfied, there will be no restriction | limiting in the addition method.

  Examples of the chain transfer agent used in the present invention include dimers of nucleus-substituted α-methylstyrene such as α-methylstyrene dimer, n-butyl mercaptan, n-octyl mercaptan, n-lauryl mercaptan, and n-dodecyl mercaptan. , And mercaptans such as t-dodecyl mercaptan, disulfides such as tetramethylthiuram disulfide and tetraethylthiuram disulfide, 2-ethylhexyl thioglycolate, terpinolene, cyclopentene, cyclohexene alone or in combination of two or more Can be used. Among these, mercaptans can be preferably used.

  The first chain transfer agent and the second chain transfer agent may be the same or different.

  Examples of the ethylenically unsaturated carboxylic acid monomer used in the present invention include monobasic ethylenically unsaturated carboxylic acid monomers such as acrylic acid and methacrylic acid, itaconic acid, maleic acid, and fumaric acid. And dibasic ethylenically unsaturated carboxylic acid monomers. These can be used alone or in combination of two or more.

  The use ratio of the ethylenically unsaturated carboxylic acid monomer is usually 0.1 to 15% by mass, preferably 0.3 to 10% by mass. By setting the amount of the ethylenically unsaturated carboxylic acid monomer used within the above range, the dispersion stability of the resulting copolymer latex can be kept good. In addition, the viscosity of the copolymer latex can be adjusted to an appropriate range that does not hinder handling.

  Other monomers copolymerizable with conjugated diene monomers and ethylenically unsaturated carboxylic acid monomers include aromatic vinyl monomers, (meth) alkyl ester monomers, and vinyl cyanide monomers. Examples thereof include monomers, (meth) acrylamide monomers, and hydroxyl group-containing ethylenically unsaturated monomers.

  Aromatic vinyl monomers include styrene, α-methyl styrene, vinyl toluene, p-methyl styrene, o-methyl styrene, m-methyl styrene, ethyl styrene, hydroxymethyl styrene, vinyl xylene, bromostyrene, vinyl benzyl. Examples include chloride, chlorostyrene, divinylbenzene, and trivinylbenzene. These can be used alone or in combination of two or more.

  Examples of the (meth) alkyl ester monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, and isobutyl (meth). Acrylate, n-amyl (meth) acrylate, isoamylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, octadecyl (meth) acrylate, cyclohexyl (meta) ) Acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, glycidyl (meth) acrylate, ethylene glycol di (meth) acrylate, 1-3 Butylene glycol di (meth) acrylate, 1,4-butylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,5-pentadiol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1 , 6-hexanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate , Tetramethylolmethane tetra (meth) acrylate, allyl (meth) acrylate, bis (4-acryloxypolyethoxyphenyl) propane, phenoxyethyl (meth) Acrylate, 2,2-bis [4-((meth) acryloxyethoxy) phenyl] propane, 2,2-bis [4-((meth) acryloxy-diethoxy) phenyl] propane, 2,2-bis [4- ((Meth) acryloxy / polyethoxy) phenyl] propane, isobornyl (meth) acrylate and the like. These can be used alone or in combination of two or more.

  Examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile and the like. These can be used alone or in combination of two or more.

  Examples of (meth) acrylamide monomers include N-monoalkyl (meth) acrylamides such as (meth) acrylamide, N-methylol (meth) acrylamide and N-methyl (meth) acrylamide, N, N-dimethyl (meth) ) N, N-dialkyl (meth) acrylamide such as acrylamide, glycidylmethacrylamide, N-alkoxy (meth) acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and the like. These can be used alone or in combination of two or more.

  Examples of the hydroxyl group-containing ethylenically unsaturated monomer include hydroxyethyl acrylate, hydroxymethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, allyl alcohol, and monoallyl ether of polyhydric alcohol. These can be used alone or in combination of two or more.

  Other monomers include, for example, aminoethyl (meth) acrylate and dimethylaminoethyl (meth) acrylate, amino group-containing ethylenic monomers such as 2-vinylpyridine, and vinyl carboxylates such as vinyl acetate, Vinyl halides such as vinyl chloride and vinylidene chloride, sulfonic acid group-containing monomers such as styrene sulfonate, 2- (meth) acryloyloxyethyl sulfonic acid, and (meth) allyl sulfonate, ethylene phosphate (meth) Examples thereof include phosphate group-containing monomers such as acrylate, propylene phosphate (meth) acrylate, and 2- (meth) acryloyloxyethyl acid phosphate. These can be used alone or in combination of two or more.

  In the embodiment of the present invention, the range of the gel fraction (m) of the first polymerization stage copolymer at the start of addition of the second polymerization stage monomer and the second chain transfer agent is usually 35. -80%, preferably 40-75%. By adjusting the gel fraction within this range, the heat resistant creep resistance and the adhesive strength can be improved.

In the embodiment of the present invention, the range of the gel fraction (n) in the finally obtained copolymer latex is usually 40 to 90%, preferably 45 to 85%, and the first polymerization. The relationship with the gel fraction (m) of the step copolymer is preferably within the range represented by the following formula.
0.8 ≦ (n) / (m) ≦ 1.25

  By adjusting the gel fraction within this range, it is possible to obtain a copolymer latex excellent in contact adhesion immediately after bonding and excellent in heat-resistant creep resistance.

  The gel fraction can be controlled by a known method, but is preferably adjusted by the amount of chain transfer agent added.

  In the embodiment of the present invention, the average particle diameter of the copolymer latex is not particularly limited, but is preferably 80 to 500 nm, more preferably 100 to 400 nm.

  The average particle diameter can be adjusted by using a method for adjusting the amount of emulsifier used in the production by emulsion polymerization or a known seed polymerization method. The composition of the latex for seed is not particularly limited, and may be the same as or different from the composition of the copolymer latex. Further, the latex for seed may be produced in the same reaction vessel or may be produced in a different other reaction vessel, and its particle size, particle size distribution, and amount used are not particularly limited. .

  In the embodiment of the present invention, as a method for producing the copolymer latex, for example, a method of performing polymerization with a radical initiator in the presence of an emulsifier in an aqueous medium can be employed.

  As the emulsifier used here, conventionally known anionic, cationic, amphoteric and nonionic emulsifiers can be used. Examples of preferred emulsifiers include, for example, anionic emulsifiers such as aliphatic soap, rosin acid soap, alkyl sulfonate, alkyl diphenyl ether disulfonate, alkyl sulfosuccinate, polyoxyethylene alkyl sulfate; polyoxyethylene alkyl ether Nonionic emulsifiers such as polyoxyethylene alkyl allyl ether and polyoxyethylene oxypropylene block copolymer. These can be used alone or in combination of two or more. The amount of the emulsifier used is preferably 0.1 parts by mass to 2.0 parts by mass with respect to 100 parts by mass of the monomer.

  In addition, it is possible to use a reactive emulsifier having a radical polymerizable double bond such as a vinyl group, an acryloyl group or a methacryloyl group in the molecule.

  The radical initiator is one that initiates addition polymerization of a monomer by radical decomposition in the presence of heat or a reducing agent, and both inorganic and organic initiators can be used. . Examples of preferred initiators include peroxodisulfate, peroxide, azobis compound and the like.

  More specific examples of such initiators include, for example, potassium peroxodisulfate, sodium peroxodisulfate, ammonium peroxodisulfate, hydrogen peroxide, t-butyl hydroperoxide, benzoyl peroxide, 2,2-azobisbutyro Nitrile, cumene hydroperoxide and the like can be mentioned. These can be used alone or in combination of two or more.

  In addition, a so-called redox polymerization method in which a reducing agent such as acidic sodium sulfite, ascorbic acid or a salt thereof, erythorbic acid or a salt thereof or Rongalite is used in combination with the above-described polymerization initiator can also be used.

  The polymerization temperature for producing the copolymer latex is, for example, 40 to 100 ° C., but is not particularly limited.

  It is also possible to employ a method of raising the polymerization temperature (so-called cooking step) in order to increase the polymerization conversion rate of each monomer after the addition of all the monomers in the polymerization system. The polymerization temperature in such a process is usually 80 to 100 ° C.

  Polymerization solid content concentration in the case of producing a copolymer latex (solid content concentration when polymerization is completed. The ratio of the solid content mass obtained by drying to the mass of the original copolymer latex (including water) ) Is preferably 35 to 65% by mass, more preferably 40 to 60% by mass, from the viewpoint of production efficiency and particle size control during emulsion polymerization.

  In the production of the copolymer latex, various known polymerization regulators can be used at the time of emulsion polymerization or at the end of emulsion polymerization, if necessary. For example, a pH adjuster, a chelating agent, etc. can be used.

  Preferable examples of the pH adjuster include sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium hydrogen carbonate, disodium hydrogen phosphate, amines such as monoethanolamine and triethanolamine, and the like. Examples of the chelating agent include sodium ethylenediaminetetraacetate.

  Here, various additives may be added to the copolymer latex of the embodiment of the present invention as needed, or other latexes may be mixed and used as long as the effect is not impaired. For example, a dispersant, an antifoaming agent, an anti-aging agent, a water resistant agent, a bactericidal agent, a thickener, a water retention agent, a crosslinking agent, and the like can be added. Moreover, urethane resin latex, acrylic resin latex, etc. can also be mixed and used. In addition, other (diene) copolymer latex may be used in combination as long as there is no problem in practical properties.

  Next, the present embodiment will be described more specifically with reference to examples and comparative examples. However, the present embodiment is not limited to the following examples unless it exceeds the gist. Each physical property was evaluated by the following method.

(1) Gel fraction The copolymer latex adjusted to pH 8 with sodium hydroxide was dried at 130 ° C. for 30 minutes to obtain a latex film. About 0.5 g of this latex film was precisely weighed. This was mixed with 30 ml of toluene and shaken for 3 hours, followed by filtration through a metal net having an opening of 32 μm, and the residue was dried at 130 ° C. for 1 hour, and the dry mass was weighed. The ratio of the dry mass of the residue to the original latex film mass was defined as the gel fraction (%).
Gel fraction (%) = (residue dry mass / latex film mass) × 100

(2) Polymerization conversion rate About 1 g of the extracted reaction solution was precisely weighed and dried at 130 ° C. for 1 hour to weigh the dry mass. The solid content (% by mass) was calculated from the ratio of the mass after drying to the mass before drying.
Solid content (mass%) = (mass after drying / mass before drying) × 100
Further, the charged solid content was calculated from the mass of the nonvolatile component and the ratio of the charged volatile monomer with respect to the charged total mass at the time of extraction.
Charged solid content (mass%) =
(Nonvolatile component mass and charged volatile monomer mass / total charged mass) × 100
The polymerization conversion rate was calculated from the ratio of the solid content of the reaction solution to the charged solid content.
Polymerization conversion rate (%) = (reaction liquid solid content / charged solid content) × 100

(3) Particle size of latex Measured by dynamic light scattering method using a light scattering photometer (Model 6000, manufactured by CNN Wood) at an initial angle of 45 degrees and a measurement angle of 135 degrees, and the number average particle diameter was determined. Asked.

(4) Contact adhesion Latex was applied to two vinyl chloride plates and dried at 50 ° C. for 5 minutes. The coated surfaces were bonded to each other and peeled by hand 1 minute after reciprocating a 2 kg roll twice, and the contact adhesiveness was judged from the strength of the peeling resistance and the state of destruction of the adhesive. The determination was made according to the following criteria.
◎ (excellent): The peel resistance is quite strong and the adhesive on both sides of the base material is agglomerated and broken ○ (Good): The peel resistance is strong and the adhesive on both sides of the base material is agglomerated and broken △ (possible ): Peeling resistance is weak and the state is peeling near the adhesive interface on both sides of the substrate. × (Not possible): Peeling resistance is very weak and the state is peeling near the adhesive interface on both sides of the substrate.

(5) Heat resistance creep resistance After applying latex to 25 mm width on two aluminum plates and drying at 50 ° C. for 5 minutes, the coated surfaces are laminated with a length of 12 mm and bonded together, and a 4.5 kg roll is applied twice. After reciprocating, it was cured for 3 days. A 1 kg weight was hung on the bonded test piece and placed in a hot air circulating dryer at 80 ° C. to conduct a creep rupture test. The time until the bonded aluminum plate peeled off was measured.

(6) Adhesive strength Latex was applied to China plywood (3 ply, thickness 5.5 mm) and canvas (No. 9) fabric in a width of 25 mm, dried at 50 ° C. for 5 minutes, and then the applied surfaces were bonded together. A 5 kg roll was reciprocated twice and then cured for 3 days. The peel strength of this bonded test piece was measured with a tensile tester. A peel strength of 180 degrees was measured at room temperature at a pulling rate of 100 mm / min.

Example A1
In a pressure-resistant reaction vessel equipped with a stirrer and a temperature control jacket, as a raw material for the initial stage of polymerization, 72 parts by mass of ion-exchanged water, 0.1 part by mass of sodium dodecylbenzenesulfonate, and a polystyrene seed latex of 0.9 nm in average particle size of 0.9 Itaconic acid in the mass part and the first polymerization stage monomer was charged all at once and sufficiently stirred at 75 ° C.

  Next, the first polymerization stage monomer described in Table 1-1 excluding itaconic acid and the first chain transfer agent were continuously added into the pressure vessel. On the other hand, an aqueous mixture comprising 22 parts by mass of water, 0.15 parts by mass of sodium hydroxide, 0.3 parts by mass of sodium dodecylbenzenesulfonate, and 1.0 parts by mass of sodium peroxodisulfate from 10 minutes after the start of the addition. Was started to initiate the polymerization reaction.

  When the addition of the first polymerization stage monomer and the first chain transfer agent is completed and the polymerization conversion rate of the first polymerization stage monomer reaches 90%, the second polymerization stage monomer and the second polymerization stage monomer The chain transfer agent was continuously added into the pressure vessel, and the polymerization reaction was continued.

  30 minutes after the addition of the second polymerization stage monomer and the second chain transfer agent is completed, the temperature in the pressure vessel is raised to 95 ° C. and maintained at 95 ° C. for 1 hour 30 minutes to complete the polymerization. did. Next, sodium hydroxide was added to adjust the pH to 8.0, and unreacted monomers were removed by a steam stripping method, and then the solid content concentration was adjusted to 50% by mass. This copolymer latex was filtered through a 325 mesh filter to obtain a copolymer latex A1. The evaluation results of the physical properties of the copolymer latex A1 are shown in Table 1-1 and Table 2-1.

Examples A2 and A3
The copolymer latexes A2 and A3 were all the same procedure as in Example A1, except that the mass% of the first polymerization stage monomer and the second polymerization stage monomer were changed as shown in Table 1-1. Manufactured. The evaluation results of the physical properties of these copolymer latexes are shown in Table 1-1 and Table 2-1.

Example A4
A copolymer latex A4 is produced by the same procedure as in Example A1, except that the mass parts a and b, which are the addition amounts of the first and second chain transfer agents, are changed as shown in Table 1-1. did. The evaluation results of the physical properties of these copolymer latexes are shown in Table 1-1 and Table 2-1.

Example A5
The composition of the first polymerization stage monomer, the composition of the second polymerization stage monomer, and the mass parts a and b, which are the addition amounts of the first and second chain transfer agents, were changed as shown in Table 1-1. Except for this, copolymer latex A5 was produced by the same procedure as in Example A1. The evaluation results of these physical properties are shown in Table 1-1 and Table 2-1.

Example A6
A copolymer latex A6 was produced in the same procedure as in Example A1, except that the polymerization conversion rate in the first polymerization stage was changed as shown in Table 1-1. The evaluation results of these physical properties are shown in Table 1-1 and Table 2-1.

Example A7
The polystyrene seed latex charged in the initial stage of polymerization was changed to 1.3 parts by mass, and the parts a and b, which are the addition amounts of the first and second chain transfer agents, were changed as shown in Table 1-1. Except for the above, copolymer latex A7 was produced by the same procedure as in Example A1. The evaluation results of the physical properties of these copolymer latexes are shown in Table 1-1 and Table 2-1.

Comparative examples B1 and B2
Except that the mass parts a and b, which are the addition amounts of the first and second chain transfer agents, were changed as shown in Table 1-2, the copolymer latexes B1 and B2 were all prepared in the same procedure as in Example A1. Manufactured. The evaluation results of these physical properties are shown in Table 1-2 and Table 2-2.

Comparative Example B3
A copolymer latex B3 was produced by the same procedure as in Example A5 except that the composition of the first polymerization stage monomer and the composition of the second polymerization stage monomer were changed as shown in Table 1-2. . The evaluation results of these physical properties are shown in Table 1-2 and Table 2-2.

Comparative Example B4
A copolymer latex B4 was produced in the same procedure as in Example A1, except that the polymerization conversion rate in the first polymerization stage was changed as shown in Table 1-2. The evaluation results of these physical properties are shown in Table 1-2 and Table 2-2.

Comparative Example 5
About the mass part b which is the addition amount of a 2nd chain transfer agent, it changes as shown in Table 1-2, and also after completion | finish of addition of a 2nd polymerization stage monomer and a 2nd chain transfer agent, t-dodecyl A copolymer latex B5 was produced by the same procedure as in Example A1, except that 2.8 parts by mass of mercaptan (based on 100 parts by mass of the second polymerization stage monomer) was added over 30 minutes. The evaluation results of these physical properties are shown in Table 1-2 and Table 2-2.

  The copolymer latex in the form of the present invention can be used for carpet backing agents, various paints, binders for coated paper, various coating agents and the like in addition to water-based adhesive applications.

Claims (5)

Emulsified 30 to 70% by mass of conjugated diene monomer, 0.1 to 15% by mass of ethylenically unsaturated carboxylic acid monomer, and 15 to 69.9% by mass of other monomers copolymerizable therewith. A method for producing a copolymer latex for aqueous adhesives comprising polymerizing,
First polymerization in which 30 to 90% by mass of all monomers including 1 to 69% by mass of the conjugated diene monomer is polymerized by adding the first chain transfer agent, and the polymerization conversion rate is 75% or more. A second polymerization stage in which the polymerization is continued by adding 10 to 70% by mass of the total monomer including 1 to 69% by mass of the conjugated diene monomer and a second chain transfer agent;
And a part by mass of the first chain transfer agent with respect to 100 parts by mass of the monomer in the first polymerization stage, and a part by mass of the second chain transfer agent with respect to 100 parts by mass of the monomer in the second polymerization stage. Is b, a and b are represented by the following formula (I):
0.1 ≦ a ≦ 5
0.2 ≦ b ≦ 10 (I)
b> a
An aqueous adhesive comprising a copolymer latex for an aqueous adhesive produced by the above method, characterized in that: The chain transfer agent is a chain transfer agent selected from mercaptans or a combination of a chain transfer agent selected from mercaptans and other chain transfer agents, and is included in the chain transfer agent used in the first polymerization stage. The chain transfer agent selected from the mercaptans contained in the chain transfer agent used in the second polymerization stage and the mass transfer part x selected from 100 parts by mass of the monomer in the first polymerization stage of the chain transfer agent selected from the mercaptans selected Mass part y with respect to 100 parts by mass of the monomer in the second polymerization stage of the following formula (II):
0.1 ≦ x ≦ 5
0.2 ≦ y ≦ 10 (II)
y> x
The water-based adhesive according to claim 1, wherein   In the second polymerization stage, when the addition of the monomer and the second chain transfer agent in the second polymerization stage is started, the gel fraction (m) of the copolymer in the first polymerization stage is 35 to 80%. The water-based adhesive according to claim 1 or 2, wherein The gel fraction (n) of the finally obtained copolymer latex is 40 to 90%, and the gel fraction (m) of the copolymer in the first polymerization stage is
0.8 ≦ (n) / (m) ≦ 1.25
The water-based adhesive according to claim 3, wherein The water-based adhesive according to any one of claims 1 to 4, which is for architectural interior use.