JP2009155535A - Chloroprene latex and adhesive composition containing the chloroprene latex - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide chloroprene latex which maintains stability while stored, and can be used over a long period of time; and to provide an adhesive composition containing the same. <P>SOLUTION: The chloroprene latex is characterized in that the particle diameter (median diameter) D50 (μm) of the latex is in a range represented by formula (1): 0.037×lnT(°C)≤D50(μm)≤0.2, (wherein, lnT (°C) represents natural logarithm of the polymerization temperature (°C)), and the weight ratio E(%) of an emulsifier contained in the latex is in a range represented by formula (2): -10×D50(μm)+3≤E(%)≤-15×D50(μm)+6. The adhesive composition contains the chloroprene latex. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a chloroprene latex having good latex long-term storage stability and good physical properties when used as an adhesive. The term “long term” in the present invention means 2 years or more in refrigerated storage at 10 ° C. and 5 months or more in normal temperature storage at 23 ° C.

  Solvent-based adhesives based on chloroprene rubber and the like have been used for various applications because of their good workability and adhesive properties.

  However, since the organic solvent used has an adverse effect on the global environment and the health of workers, and sometimes has a risk of causing a fire in the workplace, etc., studies have been made on solvent removal using chloroprene latex.

Various methods are known as chloroprene latex (for example, Patent Document 1 and Patent Document 2).
Unlike solvent-based adhesives in which the polymer chain of chloroprene rubber is spread, the latex polymer chain is shrunk and its surface is protected as an emulsifier in latex. Poor adhesion (contact property) at the time of bonding. In particular, when a large amount of an emulsifier is used, or when an increase in polymer branching due to a high molecular weight or an increase in gel content occurs, the contact property is lowered.

  As one method for solving this problem, a chloroprene copolymer latex that does not contain a gel component that becomes an insoluble part when dissolved in chloroform and an adhesive composition using the same are known (for example, patents). Literature 3, non-patent literature 1).

  However, chloroprene rubber is gradually dehydrochlorinated during storage, and the pH of the latex is lowered. Therefore, as shown in Patent Document 1 and Patent Document 2, when an emulsifier is used consisting of a metal salt of rosin acid, the stability of the latex decreases due to a decrease in pH, causing problems such as rubber precipitation. . In addition, when the physical properties are improved by not including the gel component as in Patent Document 3, the physical properties are reduced when the gel is generated due to the increase in the molecular weight during storage, so that the storage stability is good in long-term storage. This is very important in latex products.

  Since the surface of the latex particles is covered with an emulsifier, the emulsifier is indispensable for improving storage stability. On the other hand, an excessive emulsifier reduces the contact property at the time of adhesive bonding. The emulsifier is also involved in the formation of the polymerization field and the wettability to the adherend, and affects everything from the production of the latex to the physical properties of the adhesive. Therefore, these balances are very delicate and it is very important to keep the balance stable.

  Regarding the particle size of latex, for example, Patent Document 4 describes that the particle size is stable and excellent in productivity when the particle size is 20 nm or more and less than 150 nm. Further, it is described that when 10 parts by mass or more of an emulsifier and / or a dispersant is added to 100 parts by mass of the charged monomer, the physical properties of rubber finished from latex may be adversely affected.

  However, there is no description on the stability and adhesive properties of the polymer in storage in the latex state, and there has been no investigation on the storage stability and adhesive properties of chloroprene latex of particle size and emulsifier amount. is there.

Japanese Patent Publication No.51-39262 JP 2001-49043 A JP-A-8-218044 JP 2003-55409 A JETI Vol. 44 no. 12 (88 pages)

  The present invention has been made in view of this problem, and the purpose of the chloroprene latex having improved physical properties due to the absence of gel content is to maintain the latex stability during storage and is good for a long period of time. The present invention provides a chloroprene latex and an adhesive composition that maintain physical properties.

  Under these circumstances, the present inventors have intensively studied to solve the above problems, and as a result, the change in molecular weight during storage can be suppressed by keeping the particle size of the latex and the amount of the emulsifier within a certain range. The headline and the present invention have been completed. That is, in the present invention, latex particle diameter (median diameter): D50 (μm) is in a range represented by a predetermined formula, and weight fraction of emulsifier contained in latex: E (%) is predetermined. A chloroprene latex characterized by being in the range of the formula, and an adhesive composition characterized by containing it.

  Hereinafter, the present invention will be described in detail.

  The chloroprene latex of the present invention has a latex particle diameter (median diameter): D50 (μm) in a range represented by the following formula (1).

0.037 × lnT (° C.) ≦ D50 (μm) ≦ 0.2 (1)
Latex particle diameter (median diameter): When D50 (μm) is smaller than 0.037 × lnT (° C.), the storage stability of the latex is deteriorated, and when it exceeds 0.2, particles may be precipitated.

  Furthermore, the chloroprene latex of the present invention is such that the weight fraction of the emulsifier contained in the latex: E (%) is in the range represented by the following formula (2).

−10 × D50 (μm) + 3 ≦ E (%) ≦ −15 × D50 (μm) +6 (2)
When the weight fraction of the emulsifier: E (%) is smaller than −10 × D50 + 3, the stability of the latex is deteriorated, and when it is larger than −15 × D50 (μm) +6, the adhesive properties are inferior.

  Moreover, it is preferable that the amount of the emulsifier per solid content of the chloroprene latex is in the range of 2.5 to 3.5 wt% because better adhesive properties can be obtained without impairing storage stability.

  The chloroprene latex of the present invention is a latex obtained by polymerizing a chloroprene monomer, which is 2-chloro-1,3-butadiene, alone or with another monomer copolymerizable with chloroprene. If necessary, two or more other monomers copolymerizable with chloroprene may be used. Examples of other monomers copolymerizable with chloroprene include 2,3-dichloro-1,3 butadiene, butadiene, isoprene, styrene, acrylonitrile, methyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and polyethylene glycol monoacrylate. Polyethylene glycol monomethacrylate, glycerin monomethacrylate, acrylic acid, methacrylic acid, fumaric acid, maleic acid, crotonic acid, citraconic acid, 2-methacryloyloxyethyl succinic acid and the like.

  As a method for producing the chloroprene latex of the present invention, for example, chloroprene monomer, or other monomer copolymerizable with chloroprene monomer and chloroprene may be subjected to radical emulsion polymerization. Emulsion polymerization is carried out by emulsifying the monomer and emulsifier together with a polymerization initiator, a chain transfer agent, etc. at a predetermined temperature, adding a polymerization terminator at a predetermined conversion rate, and a dynamic light scattering method ( Particle size (median diameter) of latex by laser scattered light analysis: D50 (μm) is 0.037 × lnT (° C.) ≦ D50 (μm) ≦ 0.2 (where lnT (° C.) is the polymerization temperature T ( ° C) represents the natural logarithm of the emulsifier and the weight fraction of the emulsifier contained in the latex: E (%) is −10 × D50 (μm) + 3 ≦ E (%) ≦ −15 × D50 (μm) +6 may be performed.

  The particle diameter of the latex depends on the number of polymerization fields, and the particle diameter decreases as the polymerization field increases. Therefore, it can be adjusted by the amount of emulsifier, the polymerization temperature, and the amount of polymerization initiator. Generally, to reduce the particle size, the amount of emulsifier used and the polymerization initiator should be increased and the polymerization field increased. good.

  The weight fraction of the emulsifier contained in the latex can be adjusted by the charge ratio at the beginning of the polymerization, but even when the emulsifier is used at a charge ratio that does not fall within this range, the emulsifier, monomer, water, and other additives can be added. It is also possible to adjust by removing the water and unreacted monomer by concentration under reduced pressure after completion of the polymerization. The additional timing is not particularly limited, and can be arbitrarily performed from immediately after the start of polymerization to after the end of polymerization.

  The emulsifier used in the polymerization is not particularly limited as long as it is generally used for emulsion polymerization, and an anionic type, nonionic type, cationic type and the like are used. Examples of the anionic emulsifier include a carboxylic acid type, a sulfate ester type, a sulfonic acid type, and the carboxylic acid type includes, for example, an alkali metal salt of rosin acid, an alkali metal salt of fatty acid, an alkali metal salt of alkenyl succinic acid, Examples thereof include polymer compounds of alkali metal salts of polycarboxylic acids. Examples of the sulfate ester type include alkyl sulfate esters having 10 to 20 carbon atoms such as lauryl sulfate and stearyl sulfate, and polyoxyethylene lauryl ether. Examples thereof include polyoxyethylene alkyl ether sulfate esters having 10 to 20 carbon atoms such as sulfate and polyoxyethylene stearyl ether sulfate. Examples of the sulfonic acid type include decane sulfonate, lauryl sulfonate, Stearyl sulfonate and other carbon atoms having 10 to 20 carbon atoms C10-20 alkyl benzene sulfonate such as can sulfonate, lauryl benzene sulfonate, stearyl benzene sulfonate, lauryl diphenyl ether disulfonate, stearyl diphenyl ether disulfonate, etc. Examples thereof include alkyl naphthalene sulfonates having 4 to 20 carbon atoms, such as alkyl diphenyl ether sulfonates, butyl naphthalene sulfonates, and lauryl naphthalene sulfonates. Examples of the salts include lithium, sodium, potassium, and cesium. . Nonionic emulsifiers include polyvinyl alcohol, polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether and the like. Examples of the cationic emulsifier include aliphatic amine salts and aliphatic quaternary ammonium salts such as lauryltrimethylammonium chloride and alkylbenzyldimethylammonium chloride. These may be one kind or may contain two or more kinds, but sodium salt of rosin acid or sodium salt of alkyldiphenyl ether disulfonic acid is usually used because of good polymerization behavior and adhesive properties. .

  The amount of emulsifier used is not particularly limited, and latex particle diameter (median diameter): D50 (μm) is 0.037 × lnT (° C.) ≦ D50 (μm) ≦ 0.2 (where lnT (° C. ) Represents the natural logarithm of the polymerization temperature T (° C.). The amount of the emulsifier during the polymerization is adjusted so as to be in the range indicated by the polymerization temperature T, and the weight fraction of the emulsifier contained in the latex: E (%) is −10 ×. Adjustment may be made during polymerization or after completion of polymerization so as to be in the range of D50 (μm) + 3 ≦ E (%) ≦ −15 × D50 (μm) +6, for example, 100 parts by weight of chloroprene monomer On the other hand, the polymerization is started at 2 to 4 parts by weight, and 1 to 4 parts by weight is added to 100 parts by weight of the chloroprene monomer during or after the polymerization. Moreover, for particle size control and weight fraction adjustment of the emulsifier, addition is possible not only before the polymerization but also at any timing during the polymerization and after the completion of the polymerization. Moreover, it is preferable to contain 0.1-2 weight part of stabilizers which consist of an alkali metal salt of a sulfonic acid with respect to 100 weight part of chloroprenes for stabilization of superposition | polymerization. Further, the addition timing is not particularly limited, and the addition can be performed at any timing before, during, or after the polymerization. Here, as the stabilizer composed of an alkali metal salt of sulfonic acid, for example, an alkali metal salt of aliphatic sulfonic acid having 8 or less carbon atoms, such as an alkali metal salt of pentanesulfonic acid, an alkali metal salt of octanesulfonic acid, Alkali metal salt of toluene sulfonic acid, alkali metal salt of styrene sulfonic acid, alkali metal salt of naphthalene sulfonic acid, alkali metal salt of aromatic sulfonic acid such as alkali metal salt of butyl naphthalene sulfonic acid, alkali metal salt of lauryl sulfate, etc. Alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate alkali metal salt such as alkali metal salt of polyoxyethylene lauryl ether sulfate, and alkali metal salt of naphthalene sulfonic acid and formalin condensate or sulfonic acid having unsaturated bond Compound al Various compounds with alkali metal salts of sulfonic acid compounds and various copolymers and the re metal salt monomer copolymerizable thereof. Examples of the sulfonic acid compound having an unsaturated bond include an alkali metal salt of vinyl sulfonic acid, an alkali metal salt of allyl sulfonic acid, an alkali metal salt of methallyl sulfonic acid, an alkali metal salt of isoprene sulfonic acid, and styrene sulfonic acid. Examples of the monomer copolymerizable therewith include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and methyl methacrylate. Examples of the alkali metal salt include lithium, sodium, potassium, cesium and the like. These may be one kind or two or more kinds. Among them, from the viewpoint of latex stability during polymerization, a condensate of a metal salt of naphthalene sulfonic acid and formaldehyde or a metal salt of styrene sulfonic acid and methacrylic acid. An acid copolymer is preferred.

  As the polymerization initiator, a known free radical substance such as a peroxide such as potassium persulfate or ammonium persulfate, or an inorganic or organic peroxide such as hydrogen peroxide or tertiary butyl hydroperoxide may be used. it can. These may be used alone or in combination with a reducing substance, for example, a combined redox system with thiosulfate, thiosulfite, hydrosulfite, organic amine and the like. The amount of the polymerization initiator is not particularly limited, and examples thereof include 0.02 parts by weight or less with respect to 100 parts by weight of the chloroprene monomer.

  Examples of the chain transfer agent include molecular weight regulators such as alkyl mercaptans, halogen hydrocarbons, alkyl xanthogen disulfides, and sulfur. Among these, n-dodecyl mercaptan is preferable from the viewpoint of odor and workability.

  The polymerization temperature is not particularly limited and can be carried out in the range of 0 to 80 ° C, preferably in the range of 10 to 50 ° C.

  Although the completion | finish time of superposition | polymerization is not specifically limited, when productivity is considered, it is preferable to superpose | polymerize until the conversion rate of a monomer is 60 to 100%.

  The polymerization terminator is not particularly limited as long as it is a commonly used terminator, and for example, phenothiazine, 2,6-tert-butyl-4-methylphenol, hydroxylamine and the like can be used.

  The adhesive containing the chloroprene latex of the present invention can be used alone as an adhesive, but a tackifying resin, a crosslinking agent, etc. can be added depending on the required physical properties.

  The tackifying resin is not particularly limited, and examples thereof include phenol resins, terpene resins, rosin derivative resins, petroleum hydrocarbons, and the like, such as polymerized rosin, rosin modified resin, rosin modified phenol resin, rosin. Esters, alkylphenol resins, terpene resins, terpene phenols, hydrogenated rosins, hydrogenated rosin pentaerythritol esters, petroleum resins, coumarone resins, and the like are used.

  As the cross-linking agent, for example, a metal oxide such as magnesium oxide, calcium oxide, zinc oxide, an epoxy resin, a polyaziridine compound, a polyoxazoline compound, a polyisocyanate compound or the like can be used as long as it is a compound that can be uniformly mixed with chloroprene latex. it can.

  The viscosity of the adhesive mainly composed of chloroprene latex is composed of various thickeners, for example, water-soluble polymers such as polyalkylene oxide, polyvinyl alcohol, hydrophobic cellulose, associative nonionic surfactants, and carboxyl group-containing polymers. It can be adjusted to a desired value by blending an alkali-soluble thickener and a silicate compound such as hectorite. Moreover, you may mix | blend various fillers, such as anti-aging agent, antiseptic | preservative, antifreezing agent, film-forming aid, a plasticizer, clay, as needed.

  The chloroprene latex of the present invention has stable physical properties during long-term storage by balancing the particle size and the amount of emulsifier, and the adhesive composition containing the same exhibits stable physical properties.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to only these examples. In addition, the storage period in an Example and a comparative example was made into the storage for 7 days or more in 50 degreeC as acceleration conditions equivalent to 2 years in 10 degreeC.

  Each physical property was measured by the following method.

<Particle size measurement>
The latex was diluted with distilled water to 0.01 to 0.1% by mass, and the particle size was measured with Microtrac UPA (manufactured by Nikkiso Co., Ltd.). As the particle diameter, D50% particle diameter (median diameter) was used.

<Mechanical stability>
Latex that was allowed to stand in a temperature-controlled room (23 ° C.) for 30 minutes or longer and filtered with a 100-mesh stainless steel wire mesh was weighed 100.0 g to obtain a measurement sample, and latex was measured by the Marlon test method with reference to the old JISK6392. The mechanical stability of was measured. The load on the polyethylene liner was 15 kg, rotation was started, and after 10 minutes, the latex in the Marlon cup was filtered through a 100 mesh stainless steel wire mesh that had been weighed, further washed with pure water, and the precipitate was taken out. After thoroughly washing with pure water, it is dried in a gear oven at 110 ° C. until a constant weight is obtained. Thereafter, it is cooled to room temperature in a desiccator and weighed to an accuracy of 0.1 mg. The solid content of the latex was S (%), the precipitation amount was G (g), and the rubber coagulation rate C (%) relative to the solid content in the latex was measured by the following formula.

C = G / (100 × S / 100) × 100
However, when the mechanical stability was poor and the latex jumped out of the Marlon cup due to the wrapping phenomenon during the rotation, the rotation was immediately stopped and the result was unmeasurable.

<Polymer gel content and solution viscosity>
The latex was cast in a petri dish, frozen in dry ice, weighed in a vacuum dryer for 24 hours or more, and dried until the weight change was 1% or less. Thereafter, the rubber was dissolved in toluene to a concentration of 1% in terms of weight, and mixed and dissolved in a ball mill for 16 hours. The obtained solution was filtered through a 200 mesh wire mesh, washed with toluene, the residue was dried at 170 ° C. for 10 minutes, and the ratio of the weight to the weight of the dissolved rubber was rounded off to the first decimal place to obtain the gel content. It was. Further, the rubber was dissolved in toluene so as to have a concentration of 10% in terms of weight in the same manner as the gel content, and the viscosity was measured using a B-type viscometer. The measurement was conducted by immersing the sample container in a thermostat at 23 ° C. for 1 hour, Measurement was performed at 12 rpm using 3 rotors, and the value after 60 seconds was used.

<Emulsifier concentration>
The concentration per latex or solid content was calculated from the total amount of the emulsifier used for the polymerization and the post-added emulsifier.

<Adhesive formulation>
40 parts by weight of resin emulsion, 100 parts by weight of latex (trade name: E-100, Arakawa Chemical Industries, Ltd.) 1 part by weight of metal oxide (trade name: AZ-SW, Osaki Industries, Ltd.) 2 parts by weight of the agent (trade name: Adecanol UH-420, ADEKA Co., Ltd.) was mixed to prepare an adhesive composition.

<Compounding stability>
The presence or absence of rubber precipitation during the blending of the adhesive was observed.

<Adhesive strength>
Apply about 250 g / m ² of the adhesive composition with a brush as an undercoat on one side of each of No. 9 canvas (about 150 mm × 60 mm), dry at 80 ° C. for 5 minutes, and again apply the adhesive composition with a brush to 110 g / m ^2. An adherend is prepared by cooling after m ² coating and drying at 80 ° C. for 5 minutes. Then, the adhesive composition was applied at 110 g / m ² with a brush, dried at 23 ° C. for 60 minutes, and then pressure bonded using a hand roller. A test piece for measurement was cut into a size of 150 mm × 25 mm. The measurement of the adhesive strength was performed by using a Tensilon type tensile tester and pulling in a 180 ° direction at a peeling rate of 100 mm / min in an atmosphere at 23 ° C. The measurement was performed 2 minutes after the pressure bonding.

Example 1
Chloroprene, methacrylic acid, n-dodecyl mercaptan, sodium alkyldiphenyl ether disulfonate (trade name: Perex SS-H, manufactured by Kao Corporation), condensate of sodium naphthalenesulfonate and formaldehyde (product) Name: Demol N, Kao Corporation), hydrosulfite sodium, and pure water were polymerized at 40 ° C. in a 10 L autoclave equipped with a stirrer to prepare a chloroprene copolymer latex. Polymerization is carried out by continuously dropping 0.35% by weight aqueous potassium persulfate in a nitrogen atmosphere, and when the polymerization conversion rate reaches about 90%, the reaction is stopped by adding phenothiazine to adjust the amount of emulsifier. Sodium alkyldiphenyl ether disulfonate was added at a ratio of 2 parts by weight based on 100 parts by weight of the total monomers. Unreacted monomers were removed under reduced pressure and water was concentrated to obtain Latex A having a solid content of 55%.

ラテックスは所定の方法で乳化剤濃度及び粒子径を測定した後、ラテックスＡの一部を容器に入れ、５０℃雰囲気で８日間保管し、保管前後の２５℃におけるラテックスの機械的安定性、ポリマーの１０％トルエン溶液粘度、ゲル分を測定した。また、保管前後のラテックスそれぞれに対し、樹脂エマルジョン、金属酸化物、増粘剤を配合して接着剤組成物を作製し、その配合安定性、及び接着強度を測定した。配合を表２に示し、結果を表３に示す。表３の結果より、５０℃保管の前後共にラテックスの機械的安定性及び配合安定性は良好であり、保管によるゲル分の発生は無く、接着強度も良好な値であった。また、粒径及び乳化剤量の相関を図１，図２，図３に示す。

After measuring the emulsifier concentration and the particle diameter of the latex by a predetermined method, a part of the latex A is put in a container and stored in an atmosphere of 50 ° C. for 8 days. The mechanical stability of the latex at 25 ° C. before and after storage, A 10% toluene solution viscosity and a gel content were measured. Moreover, resin emulsion, a metal oxide, and a thickener were mix | blended with respect to each latex before and behind storage, the adhesive composition was produced, and the mixing | blending stability and adhesive strength were measured. The formulation is shown in Table 2, and the results are shown in Table 3. From the results shown in Table 3, the mechanical stability and blending stability of the latex were good both before and after storage at 50 ° C., no gel content was generated by storage, and the adhesive strength was also good. The correlation between the particle size and the amount of emulsifier is shown in FIGS.

実施例２
アルキルジフェニルエーテルジスルホン酸ナトリウム及びハイドロサルファイトＮａの添加量を表１に示す割合に変更した以外は実施例１に従ってラテックスＢを作製し、評価を実施した。表３の結果より、５０℃保管の前後共にラテックスの機械的安定性及び配合安定性は良好であり、保管によるゲル分の発生は無く、接着強度も非常に良好な値であった。

Example 2
Latex B was prepared and evaluated according to Example 1 except that the addition amounts of sodium alkyldiphenyl ether disulfonate and hydrosulfite Na were changed to the ratios shown in Table 1. From the results shown in Table 3, the mechanical stability and blending stability of the latex were good both before and after storage at 50 ° C., no gel was generated by storage, and the adhesive strength was also very good.

Example 3
The addition amount of sodium alkyldiphenyl ether disulfonate and hydrosulfite Na was changed to the ratio shown in Table 1, and a chloroprene monomer was added when the polymerization conversion rate exceeded 50% in order to adjust the amount of emulsifier per solid content. Except for the above, latex C was prepared according to Example 1 and evaluated. From the results shown in Table 3, the mechanical stability and blending stability of the latex were good both before and after storage at 50 ° C., no gel was generated by storage, and the adhesive strength was also very good.

Example 4
Latex D was prepared and evaluated according to Example 1 except that the polymerization conversion was changed. From the results shown in Table 3, the mechanical stability and blending stability of the latex were good both before and after storage at 50 ° C., no gel content was generated by storage, and the adhesive strength was also good.

Example 5
Latex E was produced and evaluated according to Example 1 except that the polymerization temperature was 50 ° C. From the results of Table 3, the mechanical stability and blending stability of the latex were good both before and after storage at 50 ° C., the gel content was hardly increased by storage, and the adhesive strength was also a good value.

Example 6
Latex F was prepared according to Example 1 and evaluated, except that the polymerization temperature was 10 ° C. and the amount of sodium alkyldiphenyl ether disulfonate was changed. From the results shown in Table 3, the mechanical stability and blending stability of the latex were good both before and after storage at 50 ° C., no gel content was generated by storage, and the adhesive strength was also good.

Example 7
Latex G was produced according to Example 1 and evaluated, except that the polymerization temperature was 10 ° C. and the amount of sodium alkyldiphenyl ether disulfonate and the polymerization conversion rate were changed. From the results of Table 3, the mechanical stability and blending stability of the latex were good both before and after storage at 50 ° C., the gel content was hardly increased by storage, and the adhesive strength was also a good value.

Example 8
The parts by weight of chloroprene monomer, n-dodecyl mercaptan, potassium rosinate (trade name: Longis K-25, Arakawa Chemical Co., Ltd.), sodium hydroxide, hydrosulfite sodium, and pure water shown in Table 1 Polymerization was carried out at 40 ° C. in a 10 L autoclave with a stirrer to prepare a chloroprene latex. Polymerization was carried out by continuously dropping a 0.35 wt% aqueous potassium persulfate solution under a nitrogen atmosphere. When the polymerization conversion reached about 90%, a polymerization terminator was added to stop the reaction. To adjust the amount of emulsifier, after adding 1.5 parts by weight of potassium rosinate to 100 parts by weight of chloroprene monomer, the solid content was adjusted to 55% by removing and concentrating unreacted monomers under reduced pressure. Latex H was prepared. The results are shown in Table 3. From the results shown in Table 3, the mechanical stability and blending stability of the latex were good both before and after storage at 50 ° C., no gel content was generated by storage, and the adhesive strength was also good.

Example 9
Latex I was prepared and evaluated according to Example 8 except that the polymerization temperature was 10 ° C. and the amount of potassium rosinate added after the polymerization was changed. From the results shown in Table 3, the mechanical stability and blending stability of the latex were good both before and after storage at 50 ° C., no gel content was generated by storage, and the adhesive strength was also good.

Example 10
Latex J was produced and evaluated according to Example 8 except that the polymerization temperature was 15 ° C. and the amount of potassium rosinate was changed. From the results in Table 3, the mechanical stability and blending stability of the latex were good before and after storage at 50 ° C., no gel content was generated by storage, and the adhesive strength was also good.

Example 11
Example 8 except that the polymerization temperature was set to 15 ° C., the amount of potassium rosinate was changed, and a chloroprene monomer was added when the polymerization conversion rate exceeded 50% in order to adjust the amount of emulsifier per solid content. Latex K was prepared according to the above and evaluated. From the results in Table 3, the mechanical stability and blending stability of the latex were good before and after storage at 50 ° C., no gel content was generated by storage, and the adhesive strength was also good.

Example 12
Latex L was prepared according to Example 8 and evaluated, except that the polymerization temperature was 15 ° C. and the amount of potassium rosinate added after polymerization and the polymerization conversion were changed. From the results shown in Table 3, the mechanical stability and blending stability of the latex were good both before and after storage at 50 ° C., no gel content was generated by storage, and the adhesive strength was also good.

Example 13
Latex M was produced and evaluated according to Example 8 except that the polymerization temperature was 20 ° C. and the amount of potassium rosinate was changed. From the results shown in Table 3, the mechanical stability and blending stability of the latex were good both before and after storage at 50 ° C., there was no increase in gel content due to storage, and the adhesive strength was also a good value.

Comparative Example 1
Latex a was prepared and evaluated according to Example 1 except that the amounts of sodium alkyldiphenyl ether disulfonate and hydrosulfite Na used were changed to the ratios shown in Table 4. The results are shown in Table 5. From the results shown in Table 5, the mechanical stability and blending stability of the latex were good both before and after storage at 50 ° C., but deposits were found on the bottom of the container due to storage.

比較例２
アルキルジフェニルエーテルジスルホン酸ナトリウムの添加量を表４に示す割合に変更した以外は実施例１に従ってラテックスｂを作製し、評価を実施した。結果を表５に示す。表５の結果より、５０℃保管の前後共にラテックスの機械的安定性及び配合安定性は良好であるが、接着強度が低かった。

Comparative Example 2
Latex b was prepared according to Example 1 and evaluated, except that the amount of sodium alkyldiphenyl ether disulfonate was changed to the ratio shown in Table 4. The results are shown in Table 5. From the results of Table 5, the mechanical stability and blending stability of the latex were good before and after storage at 50 ° C., but the adhesive strength was low.

Comparative Example 3
Latex c was produced according to Example 1 and evaluated, except that the amount of sodium alkyldiphenyl ether disulfonate (usage ratio) and the polymerization temperature were changed to the ratios shown in Table 4. The results are shown in Table 5. From the results shown in Table 5, a gel was generated by storage at 50 ° C., and the adhesive strength decreased after storage.

Comparative Example 4
Latex d was prepared and evaluated according to Example 1 except that the amount of sodium alkyldiphenyl ether disulfonate and the polymerization temperature were changed to the ratios shown in Table 4. The results are shown in Table 5. From the results shown in Table 5, a gel was generated by storage at 50 ° C., and the adhesive strength decreased after storage.

Comparative Example 5
Latex e was prepared and evaluated according to Example 1 except that the amount of sodium alkyldiphenyl ether disulfonate and the polymerization temperature were changed to the ratios shown in Table 4. The results are shown in Table 5. From the results of Table 5, the mechanical stability and compounding stability of the latex were poor both before and after storage at 50 ° C., and rubber was precipitated.

Comparative Example 6
Latex f was produced and evaluated according to Example 7 except that the amount of potassium rosinate added was changed to the ratio shown in Table 4. The results are shown in Table 5. From the results in Table 5, the mechanical stability and blending stability of the latex were good both before and after storage at 50 ° C., but the gel content increased greatly and the adhesive strength decreased.

Comparative Example 7
Latex g was prepared and evaluated according to Example 5 except that the amount of potassium rosinate added and the polymerization temperature were changed to the ratios shown in Table 4. The results are shown in Table 5. From the results shown in Table 5, a gel was generated by storage at 50 ° C., and the adhesive strength decreased after storage.

It is a figure which shows the relationship between the polymerization temperature and D50 (micrometer) in an Example and a comparative example. The solid line in the figure indicates the range of the formula (1), and the letter next to each plot indicates the corresponding latex (upper case alphabet is an example, lower case alphabet is a comparative example). It is a figure which shows the relationship between the particle diameter in an Example and a comparative example, and the amount (%) of the emulsifier in latex. The solid line in the figure indicates the range of the formula (2), and the letter beside each plot indicates the corresponding latex. It is a figure which shows the emulsifier amount (%) per solid content in an Example and a comparative example. The dotted lines in the figure indicate the upper and lower limits of wt% described in claim 2.

Claims (3)

The particle diameter (median diameter) of latex: D50 (μm) is in the range represented by the following formula (1), and the weight fraction of emulsifier contained in the latex: E (%) is represented by the following formula (2 A chloroprene latex characterized by being in the range indicated by
0.037 × lnT (° C.) ≦ D50 (μm) ≦ 0.2 (1)
(In the formula, lnT (° C.) represents the natural logarithm of the polymerization temperature T (° C.).)
−10 × D50 (μm) + 3 ≦ E (%) ≦ −15 × D50 (μm) +6 (2) The chloroprene latex according to claim 1, wherein the amount of emulsifier per solid content is 2.5 to 3.5 wt%. An adhesive composition comprising the chloroprene latex according to claim 1 or 2.

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