WO2020045339A1

WO2020045339A1 - Method for producing polymer latex

Info

Publication number: WO2020045339A1
Application number: PCT/JP2019/033270
Authority: WO
Inventors: 吉隆佐藤; 小出村　順司
Original assignee: 日本ゼオン株式会社
Priority date: 2018-08-29
Filing date: 2019-08-26
Publication date: 2020-03-05
Also published as: CN112513147A; JP7342871B2; BR112021003445A2; JPWO2020045339A1; KR20210049800A

Abstract

The present invention provides a method for producing a polymer latex, which comprises a step wherein an organic solvent is removed by distillation from an emulsion that is obtained by mixing an aqueous solution of an emulsifying agent with a solution or dispersion liquid of a polymer, said solution or dispersion liquid being obtained by dissolving or dispersing the polymer in the organic solvent. With respect to this method for producing a polymer latex, the removal of the organic solvent from the emulsion by means of distillation is performed within a container in which the pressure is controlled to 0.02 MPa or more in terms of a gauge pressure.

Description

Method for producing polymer latex

The present invention relates to a method for producing a polymer latex, and more particularly, to a method for producing a polymer latex that can be produced in a short time while achieving a high yield.

Conventionally, a film molded product such as a dip molded product obtained by dip molding a latex composition containing a latex of natural rubber or synthetic rubber has been suitably used as a nipple, a balloon, a glove, a balloon, a sack and the like.

For example, in Patent Literature 1, as a method for producing a synthetic rubber latex, an emulsion is obtained by mixing a solution of a synthetic rubber in which a synthetic rubber is dissolved in an organic solvent and an aqueous solution of an emulsifier. A method for removing an organic solvent by heating an obtained emulsion at a temperature higher than the boiling point of the organic solvent under reduced pressure conditions is disclosed. However, the technique of Patent Document 1 has a problem that it takes a long time to remove the organic solvent, and thus the productivity is poor.

Japanese Patent No. 5260737

An object of the present invention is to provide a method for producing a polymer latex that can be produced in a short time while realizing a high yield.

The present inventors have conducted intensive studies to solve the above problems, and as a result, a polymer solution or dispersion obtained by dissolving or dispersing a polymer in an organic solvent and an aqueous solution of an emulsifier were obtained. When the organic solvent is distilled off from the emulsion, the above-mentioned object can be achieved by performing the distillation of the organic solvent from the emulsion in a vessel adjusted to a pressure condition of 0.02 MPa or more at a gauge pressure. And completed the present invention.

That is, according to the present invention, the organic solvent is distilled off from the emulsion obtained by mixing the polymer solution or dispersion obtained by dissolving or dispersing the polymer in the organic solvent and the aqueous solution of the emulsifier. A method for producing a polymer latex, comprising:
There is provided a method for producing a polymer latex, in which the organic solvent is distilled off from the emulsion in a vessel adjusted to a pressure condition of 0.02 MPa or more at a gauge pressure.

In the method for producing a polymer latex of the present invention, the content of the organic solvent in the emulsion before the organic solvent is distilled off is preferably 30 to 60% by weight.
In the method for producing a polymer latex of the present invention, the organic solvent is preferably distilled off from the emulsion in a vessel adjusted to a gauge pressure of 0.02 to 0.18 MPa.
In the method for producing a polymer latex of the present invention, it is preferable that the organic solvent is distilled off from the emulsion at a temperature equal to or higher than the boiling point of the organic solvent.
In the method for producing a polymer latex of the present invention, it is preferable that the organic solvent is an organic solvent selected from cyclohexane, normal hexane, cyclopentane, and normal pentane.
In the method for producing a polymer latex of the present invention, it is preferable that the distillation of the organic solvent is performed by heating by a method in which steam whose pressure is adjusted is charged into a jacket provided in the container.
In the method for producing a polymer latex of the present invention, the polymer is preferably a synthetic polyisoprene and / or a styrene-isoprene-styrene copolymer.
In the method for producing a polymer latex of the present invention, the content of the emulsifier in the emulsion before removing the organic solvent is 0.1 to 30 parts by weight based on 100 parts by weight of the polymer. Preferably, there is.

According to the method for producing a polymer latex of the present invention, production can be performed in a short time while achieving a high yield, thereby improving productivity.

FIG. 1 is a diagram illustrating an example of an emulsifying apparatus used in the method for producing a polymer latex of the present invention.

The method for producing the polymer latex of the present invention comprises:
A polymer solution or dispersion obtained by dissolving or dispersing the polymer in an organic solvent, and an emulsion obtained by mixing an aqueous solution of an emulsifier, comprising a step of distilling off the organic solvent,
The organic solvent is distilled off from the emulsion in a container adjusted to a pressure condition of 0.02 MPa or more at a gauge pressure.

<Emulsion>
The emulsion used in the production method of the present invention is obtained by mixing a polymer solution or dispersion obtained by dissolving or dispersing a polymer in an organic solvent with an aqueous solution of an emulsifier.

The polymer solution or dispersion is not particularly limited as long as it is a solution or dispersion in which the polymer is dissolved or dispersed in an organic solvent.

The polymer is not particularly limited and various polymers can be used without limitation. Examples thereof include natural rubber; homopolymers of conjugated diene monomers such as synthetic polybutadiene, synthetic polyisoprene, and synthetic polychloroprene; Copolymers: styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-isoprene-styrene block copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-isoprene copolymer, acrylonitrile-butadiene-isoprene copolymer And a conjugated diene monomer such as butyl acrylate-butadiene copolymer and another monomer copolymerizable therewith; an acrylate (co) polymer; Among these, natural rubber, synthetic polyisoprene, and styrene-isoprene-styrene block copolymer are preferable, and synthetic polyisoprene and styrene-isoprene- are preferable from the viewpoint that the effect of the production method of the present invention is higher. Styrene block copolymers are more preferred.

Hereinafter, the case where the polymer constituting the solution or dispersion of the polymer used in the production method of the present invention is a synthetic polyisoprene and / or a styrene-isoprene-styrene block copolymer will be exemplified. The polymer solution or dispersion used in the method is not limited to the solution or dispersion of the synthetic polyisoprene and / or styrene-isoprene-styrene block copolymer.

The synthetic polyisoprene may be a homopolymer of isoprene or a copolymer of isoprene and another ethylenically unsaturated monomer copolymerizable with isoprene. The content of the isoprene unit in the synthetic polyisoprene is preferably 70% by weight or more based on all the monomer units, since a film molded body such as a dip molded body having flexibility and excellent tensile strength can be easily obtained. The content is more preferably 90% by weight or more, further preferably 95% by weight or more, and particularly preferably 100% by weight (a homopolymer of isoprene).

Other ethylenically unsaturated monomers copolymerizable with isoprene include, for example, conjugated diene monomers other than isoprene such as butadiene, chloroprene and 1,3-pentadiene; acrylonitrile, methacrylonitrile, fumaronitrile, α- Ethylenically unsaturated nitrile monomers such as chloroacrylonitrile; vinyl aromatic monomers such as styrene and alkylstyrene; methyl (meth) acrylate (meaning "methyl acrylate and / or methyl methacrylate" And ethyl (meth) acrylate), ethylenically unsaturated carboxylic acid ester monomers such as ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate; Is mentioned. These other ethylenically unsaturated monomers copolymerizable with isoprene may be used alone or in combination of two or more.

Synthetic polyisoprene can be prepared in a known manner, for example, using a Ziegler-based polymerization catalyst comprising trialkylaluminum-titanium tetrachloride or an alkyllithium polymerization catalyst such as n-butyllithium or sec-butyllithium in an organic solvent using isoprene. And, by solution-polymerizing another copolymerizable ethylenically unsaturated monomer used as needed, a synthetic polyisoprene obtained by dissolving a synthetic polyisoprene in an organic solvent can be obtained as a solution of a synthetic polyisoprene. . In addition, the solution of the synthetic polyisoprene obtained by the solution polymerization may be used as it is in the emulsification step, but after taking out the solid synthetic polyisoprene from the solution obtained by the solution polymerization, the solution is dissolved in an organic solvent. , May be used.

Examples of the organic solvent used for the polymerization include, for example, aromatic hydrocarbon solvents such as benzene, toluene, and xylene; alicyclic hydrocarbon solvents such as cyclopentane, cyclopentene, cyclohexane, and cyclohexene; butane, normal pentane, normal hexane, and the like. Suitable examples include aliphatic hydrocarbon solvents such as heptane; halogenated hydrocarbon solvents such as methylene chloride, chloroform and ethylene dichloride. In addition, even when solid synthetic polyisoprene is taken out of a solution obtained by solution polymerization and then dissolved again in an organic solvent, these organic solvents can be suitably used.

イソ As the isoprene units in the synthetic polyisoprene, there are four types of cis-bond units, trans-bond units, 1,2-vinyl-bond units, and 3,4-vinyl-bond units, depending on the bonding state of isoprene. From the viewpoint of improving the tensile strength of the film molded body such as the obtained dip molded body, the content ratio of the cis-bond unit in the isoprene unit contained in the synthetic polyisoprene is preferably at least 70% by weight based on all the isoprene units, It is more preferably at least 90% by weight, further preferably at least 95% by weight.

The weight average molecular weight of the synthetic polyisoprene is preferably 10,000 to 5,000,000, more preferably 500,000 to 5,000,000, and still more preferably, in terms of standard polystyrene by gel permeation chromatography analysis. Is from 800,000 to 3,000,000. When the weight average molecular weight of the synthetic polyisoprene is in the above range, the tensile strength of the obtained film molded body in the case of a film molded body such as a dip molded body is improved, and the synthetic polyisoprene latex is easily manufactured. Tend.

ポリマー The polymer Mooney viscosity (ML1 + 4, 100 ° C) of the synthetic polyisoprene is preferably 50 to 80, more preferably 60 to 80, and further preferably 70 to 80.

Styrene-isoprene-styrene block copolymer is a block copolymer of styrene and isoprene. The content ratio of the styrene unit to the isoprene unit in the styrene-isoprene-styrene block copolymer is not particularly limited, but is usually from 1:99 to 90:10, preferably from 3 to 9, based on the weight ratio of “styrene unit: isoprene unit”. : 97 to 70:30, more preferably 5:95 to 50:50, even more preferably 10:90 to 30:70.

The styrene-isoprene-styrene block copolymer can be prepared by a conventionally known method, for example, using a Ziegler-based polymerization catalyst composed of trialkylaluminum-titanium tetrachloride or an alkyllithium polymerization catalyst such as n-butyllithium or sec-butyllithium. By block copolymerizing isoprene and styrene in an organic solvent, a styrene-isoprene-styrene block copolymer solution obtained by dissolving a styrene-isoprene-styrene block copolymer in an organic solvent can be obtained. it can. The styrene-isoprene-styrene block copolymer solution obtained by the block copolymerization may be used as it is in the emulsification step, but the solid styrene-isoprene-styrene block is obtained from the solution obtained by the block copolymerization. After taking out the copolymer, the copolymer may be dissolved in an organic solvent and used. Examples of the organic solvent used for the polymerization include the same ones as the above-mentioned synthetic isoprene.

The content ratio of the cis-bond unit in the isoprene unit contained in the styrene-isoprene-styrene block copolymer is, with respect to all the isoprene units, from the viewpoint of improving the tensile strength of the obtained film-formed body such as the dip-formed body. It is preferably at least 90% by weight, more preferably at least 95% by weight, even more preferably at least 98% by weight.

The weight average molecular weight of the styrene-isoprene-styrene block copolymer is preferably from 10,000 to 1,000,000, more preferably from 50,000 to 500, in terms of standard polystyrene by gel permeation chromatography analysis. 000, more preferably 100,000 to 300,000. By setting the weight average molecular weight of the styrene-isoprene-styrene block copolymer within the above range, when a film molded product such as a dip molded product is obtained, the tensile strength of the obtained film molded product is improved, and styrene-isoprene is obtained. -Styrene block copolymer latex tends to be easily produced.

ポリマー The polymer Mooney viscosity (ML1 + 4, 100 ° C.) of the styrene-isoprene-styrene block copolymer is preferably 50 to 80, more preferably 60 to 80, and even more preferably 70 to 80.

The content of the polymer in the polymer solution or dispersion used in the production method of the present invention is not particularly limited, but is preferably 3 to 30% by weight, more preferably 5 to 20% by weight, and further preferably It is 7 to 15% by weight.

乳化 The emulsifier constituting the aqueous solution of the emulsifier used in the production method of the present invention is not particularly limited, but an anionic emulsifier can be preferably used. Examples of the anionic emulsifier include fatty acid salts such as sodium laurate, potassium myristate, sodium palmitate, potassium oleate, sodium linolenate, sodium rosinate, potassium rosinate; sodium dodecylbenzenesulfonate, dodecylbenzenesulfonate Alkylbenzene sulfonates such as potassium, sodium decylbenzenesulfonate, potassium decylbenzenesulfonate, sodium cetylbenzenesulfonate, potassium cetylbenzenesulfonate; sodium di (2-ethylhexyl) sulfosuccinate, di (2-ethylhexyl) sulfosuccinate Alkyl sulfosuccinates such as potassium and sodium dioctyl sulfosuccinate; alkyl sulfates such as sodium lauryl sulfate and potassium lauryl sulfate Teru salts; polyoxyethylene alkyl ether sulfates such as sodium polyoxyethylene lauryl ether sulfate and potassium polyoxyethylene lauryl ether sulfate; monoalkyl phosphates such as sodium lauryl phosphate and potassium lauryl phosphate; .

Among these anionic emulsifiers, fatty acid salts, alkyl benzene sulfonates, alkyl sulfosuccinates, alkyl sulfates and polyoxyethylene alkyl ether sulfates are preferred, and the generation of aggregates in the resulting polymer latex is more appropriate. From the viewpoint that the stability of the obtained polymer latex can be further improved, fatty acid salts and alkylbenzene sulfonates are more preferable, fatty acid salts are more preferable, and sodium rosinate and potassium rosinate are preferable. Particularly preferred. It is also preferable to use a combination of a fatty acid salt and an alkylbenzene sulfonate.

The content of the emulsifier in the aqueous solution of the emulsifier used in the production method of the present invention is not particularly limited, but is preferably 0.1 to 5% by weight, more preferably 0.3 to 3% by weight, and still more preferably 0 to 3% by weight. 0.5 to 2% by weight.

In the production method of the present invention, a polymer solution or dispersion obtained by dissolving or dispersing such a polymer in an organic solvent, and an aqueous solution of an emulsifier are supplied to a mixing device, and mixed. , An emulsion can be obtained. When obtaining an emulsion, it is preferable that the solution or dispersion of the polymer and the aqueous solution of the emulsifier are continuously supplied to a mixing device to obtain an emulsion continuously.

Here, FIG. 1 is a diagram showing an example of an emulsifying apparatus used in the method for producing a polymer latex of the present invention. As shown in FIG. 1, the emulsifying apparatus shown in FIG. 1 includes a polymer tank 10, an emulsifier tank 20, a mixing apparatus 30, a storage tank 40, a distillation pipe 60, a condenser 70, And a solvent recovery tank 80.

In the following, the method for producing an emulsion used in the present invention will be described with reference to FIG. 1, but the present invention is not particularly limited to the embodiment using the emulsifying apparatus shown in FIG.

That is, with reference to FIG. 1, the polymer solution or dispersion from the polymer tank 10 and the aqueous solution of the emulsifier from the emulsifier tank 20 are continuously sent to the mixing device 30, respectively. By continuously mixing the solution or dispersion of the polymer and the aqueous solution of the emulsifier in 30, an emulsion can be obtained continuously. In the emulsifying apparatus shown in FIG. 1, the emulsified liquid thus continuously obtained is continuously supplied to the storage tank 40.

At this time, when the solution or dispersion of the polymer and the aqueous solution of the emulsifier are continuously sent to the mixing device 30, the supply ratio thereof is not particularly limited, but the emulsification of the polymer is allowed to proceed more appropriately. From the viewpoint that a polymer solution or a dispersion liquid: aqueous solution of an emulsifier can be obtained, the volume ratio is preferably 1: 2 to 1: 0.3, more preferably 1: 1.5 to 1: 0.5. , More preferably 1: 1 to 1: 0.7.

The method for continuously feeding the polymer solution or dispersion and the aqueous solution of the emulsifier from the polymer tank 10 and the emulsifier tank 20 to the mixing device 30 is not particularly limited. The aqueous solution of the emulsifier may be directly sent to the mixing device 30 by a pump, or a premixing device such as a line mixer may be provided upstream of the mixing device 30 to provide a premixing device. The pre-mixing may be performed in such a manner that the pre-mixed state is sent to the mixing device 30 in the pre-mixed state.

The mixing device 30 is not particularly limited, but is preferably a mixing device capable of continuously mixing, for example, a product name “TK Pipeline Homomixer” (manufactured by Tokushu Kika Kogyo Co., Ltd.), and a product name “ Colloid mill "(manufactured by Shinko Pantech), trade name" Slasher "(manufactured by Nippon Coke Industry), trade name" trigonal wet pulverizer "(manufactured by Mitsui Miike Kakoki Co., Ltd.), trade name" Cavitron "(eurotech) ), Trade name "Milder" (manufactured by Taiheiyo Kiko), trade name "Fine Flow Mill" (manufactured by Taiheiyo Kiko) and the like. The conditions of the mixing operation by the mixing device 30 are not particularly limited, and a processing temperature, a processing time, and the like may be appropriately selected so that a desired dispersion state is obtained.

The temperature of the solution or dispersion of the polymer and the aqueous solution of the emulsifier when the polymer solution or dispersion and the aqueous solution of the emulsifier are continuously fed to the mixing device 30 are not particularly limited. The temperature is preferably from 20 to 100 ° C., more preferably from 40 to 90 ° C., and still more preferably from 60 to 80 ° C., from the viewpoint that satisfactorily can be carried out. The temperature at which these are mixed is the temperature at which the polymer solution or dispersion is stored in the polymer tank 10 and the aqueous solution of the emulsifier is mixed with the emulsifier tank so that the mixing temperature becomes the desired temperature. What is necessary is just to control by adjusting the temperature at the time of storing in 20 respectively. For example, when the polymer solution or dispersion at 60 ° C. and the aqueous solution of the emulsifier at 60 ° C. are mixed by the mixing device 30, the polymer solution or dispersion is stored in the polymer tank 10. At 60 ° C., and the temperature when the aqueous solution of the emulsifier is stored in the emulsifier tank 20 may be 60 ° C.

The content of the organic solvent in the emulsion used in the production method of the present invention is usually 30 to 60% by weight, preferably 35 to 60% by weight based on 100% by weight of all components constituting the emulsion. %, More preferably 37 to 50% by weight.

The content of the emulsifier in the emulsion used in the production method of the present invention is generally 0.1 to 30 parts by weight, preferably 1 to 20 parts by weight, more preferably 3 to 20 parts by weight, per 100 parts by weight of the polymer. １５15 parts by weight.

<Organic solvent distillation step>
In the production method of the present invention, as described above, a polymer solution or dispersion obtained by dissolving or dispersing the polymer in an organic solvent, and an emulsion obtained by mixing an aqueous solution of an emulsifier, An organic solvent distilling step of distilling (removing) the organic solvent is provided.
Then, in the production method of the present invention, the distillation (removal) of the organic solvent from the emulsion in such an organic solvent distilling step is performed in a vessel adjusted to a pressure condition of 0.02 MPa or more by gauge pressure. It is performed in.

Hereinafter, a specific embodiment of the organic solvent distilling step of the production method of the present invention will be described with reference to FIG. 1, but the present invention is particularly limited to an embodiment using the emulsifying apparatus shown in FIG. Not something.

That is, a specific mode of the organic solvent distilling step of the production method of the present invention will be described with reference to FIG. 1. In the organic solvent distilling step, the organic solvent is sent from the mixing device 30 and stored in the storage tank 40. The organic solvent contained in the emulsion is distilled off in a state where the pressure in the storage tank 40 is controlled to a pressure of 0.02 MPa or more by gauge pressure for the emulsion.

Here, the storage tank 40 includes the stirring blade 50, and further includes a jacket (not shown) for circulating the steam on the outside thereof. Above the storage tank 40, a distillation pipe 60 and a condenser 70 connected to the distillation pipe 60 are provided.

In the organic solvent distilling step of the production method of the present invention, the pressure in the storage tank 40 is adjusted and the organic solvent is distilled off as follows. That is, in the organic solvent distilling step of the manufacturing method of the present invention, the system including the storage tank 40, the distilling pipe 60, and the condenser 70 is kept in a closed system sealed from the outside air, and While the emulsion is being stirred, steam whose pressure has been adjusted is continuously fed into a jacket provided outside the storage tank 40 to heat the emulsion stored in the storage tank 40. Then, the pressure in the storage tank 40 is increased by evaporating (evaporating or boiling) the organic solvent from the heated emulsion, whereby the inside of the storage tank 40 is pressurized. On the other hand, a part of the organic solvent vaporized from the heated emulsion passes through the distillation pipe 60, is cooled by the condenser 70, and is recovered in the organic solvent recovery tank 80.

In the organic solvent distillation step of the production method of the present invention, the organic solvent is distilled off while maintaining the pressurized state by utilizing the pressure increase inside the storage tank 40 due to the vaporization of the organic solvent. Is what you do. Specifically, the organic solvent is distilled off in a state where the pressure inside the storage tank 40 is maintained under a pressure condition of 0.02 MPa (gauge pressure) or more. The upper limit of the pressure inside the storage tank 40 in the organic solvent distillation step is not particularly limited, but is preferably 0.18 MPa (gauge pressure) or less from the viewpoint of equipment. In the organic solvent distillation step, the organic solvent is preferably distilled while maintaining the pressure inside the storage tank 40 at a pressure of 0.05 to 0.09 MPa (gauge pressure). More preferably, the organic solvent is distilled off while maintaining the pressure condition of 0.07 to 0.09 MPa (gauge pressure). In addition, the pressure inside the storage tank 40 in the organic solvent distillation step can be adjusted by, for example, a heating temperature when the emulsion stored in the storage tank 40 is heated. For example, as the heating temperature increases, the pressure can be increased.

According to the organic solvent distilling step of the production method of the present invention, the organic solvent is distilled off under such a pressurized condition of 0.02 MPa (gauge pressure) or more, and the distillation is performed under the pressurized condition. By performing the removal, the organic solvent contained in the emulsion can be distilled off in a short time while achieving a high yield. In particular, the inventors of the present invention have studied that, although the distillation of the organic solvent is generally performed under reduced pressure conditions, conversely, when the pressure is increased to 0.02 MPa (gauge pressure) or more. It has been found that the time required for distilling off the organic solvent is reduced, and based on such knowledge, the distilling off of the organic solvent is performed under a pressure condition of 0.02 MPa (gauge pressure) or more.

In addition, according to the organic solvent evaporating step of the production method of the present invention, the foaming of the liquid surface can be suppressed by applying a pressure condition of 0.02 MPa (gauge pressure) or more. The amount of the emulsified liquid is relatively large, preferably 50 to 85% by volume, more preferably 55 to 85% by volume, and still more preferably 70 to 85% by volume with respect to the volume of the storage tank 40. Even when the amount is relatively large, it is possible to effectively suppress the problem that a part of the emulsion flows into the condenser 70 due to foaming and lowers the yield. As a result, the productivity can be improved.

Furthermore, according to the organic solvent distilling step of the production method of the present invention, since the pressure is 0.02 MPa (gauge pressure) or more, the inside of the storage tank 40 is filled with the vaporized organic solvent, This allows the wall surface of the storage tank 40 to be kept wet during the removal of the organic solvent. Therefore, even when the emulsified liquid adheres to the wall surface of the storage tank 40, it is possible to effectively suppress the solidification of the emulsified liquid and the remaining of the polymer component adhered thereto. It is possible to suppress a decrease in the yield due to the polymer component remaining on the wall surface, and to realize a high yield.

When the organic solvent is distilled off under a pressure condition of 0.02 MPa (gauge pressure) or more, the heating temperature for heating the emulsion stored in the storage tank 40 is not particularly limited. The temperature may be set according to the desired pressure, but the boiling point is higher than the boiling point Tb of the organic solvent contained in the emulsion (that is, the organic solvent derived from the polymer solution or dispersion) under atmospheric pressure. The temperature is preferably Tb or higher, more preferably in the range of Tb + 1 to Tb + 35 ° C, more preferably in the range of Tb + 5 to Tb + 35 ° C, and still more preferably in the range of Tb + 10 to Tb + 30 ° C. When two or more organic solvents are contained in the emulsion, the heating temperature may be set based on the boiling point of the organic solvent having the higher content. By setting the heating temperature within the above range, the pressure applied inside the storage tank 40 in the organic solvent distillation step can be appropriately controlled. Note that the heating temperature can be appropriately adjusted by adjusting the flow rate and the flow rate of the steam to be charged into the jacket provided outside the storage tank 40.

In addition, the pressure applied to the inside of the storage tank 40 in the organic solvent distillation step may be within the above range in terms of gauge pressure, but is preferably 0.1213 to 0.2813 MPa, more preferably 0.1513 to absolute pressure. The pressure is 0.1913 MPa, and more preferably 0.1713 to 0.1913 MPa.

In addition, in the organic solvent distillation step, in order to maintain the pressure, the system including the storage tank 40, the distillation pipe 60, and the condenser 70 is maintained in a closed system that is closed from the outside air, and the organic solvent is removed. Although it is preferable to perform distillation, on the other hand, immediately after the heating of the storage tank 40 is started, it is connected to the upper part of the condenser 70 for the purpose of removing air contained in the storage tank 40. The pressure valve may be opened to remove air. At this time, it is desirable to close the pressure valve after the removal of the air contained in the storage tank 40 is completed and the liquefaction of the organic solvent by the condenser 70 is confirmed, thereby forming a closed system.

Alternatively, the pressure in the storage tank 40 in the organic solvent distillation step may be adjusted by the heating temperature. In addition to the adjustment by the heating temperature, the pressure is adjusted by a pressure valve connected to the upper part of the condenser 70. The methods may be used in combination.

In the production method of the present invention, the distillation of the organic solvent from the emulsion under the pressure condition of 0.02 MPa (gauge pressure) or more in the organic solvent distillation step is based on 100% by weight of the polymer in the emulsion. The process is preferably performed until the content of the organic solvent in the emulsion becomes preferably 500 ppm by weight or less, more preferably 100 ppm by weight or less. In the production method of the present invention, the organic solvent is distilled off from the emulsion under a pressure condition of 0.02 MPa (gauge pressure) or more. %, After removing the organic solvent under a pressure condition of 0.02 MPa (gauge pressure) or more until the content of the organic solvent in the emulsion with respect to% is preferably reduced to about 1% by weight or less. Alternatively, the organic solvent may be distilled off under reduced pressure conditions in combination. In this case, a decompression pump may be connected to the downstream side of the condenser 70 so that the pressure is reduced by the decompression pump.

As described above, according to the production method of the present invention, a polymer latex can be obtained. Incidentally, the polymer latex thus obtained is usually blended in the field of latex, such as a pH adjuster, an antifoaming agent, a preservative, a chelating agent, an oxygen scavenger, a dispersant, an antioxidant and the like. Additives may be blended.

Examples of the pH adjuster include hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide; carbonates of alkali metals such as sodium carbonate and potassium carbonate; hydrogen carbonates of alkali metals such as sodium hydrogen carbonate; ammonia Organic amine compounds such as trimethylamine and triethanolamine; and the like, with preference given to alkali metal hydroxides or ammonia.

濃縮 If necessary, a concentration operation by centrifugation may be performed to increase the solid content of the polymer latex.

体積 The volume average particle diameter of the polymer latex produced by the production method of the present invention is preferably 0.1 to 10 μm, more preferably 0.5 to 3 μm, and still more preferably 1 to 2 μm. By setting the volume average particle diameter in the above range, the viscosity of the latex becomes appropriate and the handling becomes easy, and the formation of a film on the latex surface when the polymer latex is stored can be suppressed.

固形 The solid content of the polymer latex produced by the production method of the present invention is preferably 30 to 70% by weight, more preferably 40 to 70% by weight. By setting the solid content concentration in the above range, it is possible to suppress separation of the polymer particles when the polymer latex is stored, and it is possible to suppress the occurrence of coarse aggregates due to aggregation of the polymer particles. .

The polymer latex of the present invention thus obtained can be made into a latex composition by, for example, blending various additives such as a cross-linking agent, and the latex composition can be used as a dip molded article or the like. In addition to being used for obtaining a film molded product, it can also be used for adhesives.

Hereinafter, the present invention will be described based on more detailed examples, but the present invention is not limited to these examples. In the following, “parts” are based on weight unless otherwise specified. Tests and evaluations were as follows.

<Example 1>
(Preparation of normal hexane solution (a) of synthetic polyisoprene)
Synthetic polyisoprene (trade name “Nipol IR2200L (R)”, manufactured by Zeon Corporation) was mixed with normal hexane (boiling point: 69 ° C.), and the temperature was raised to 60 ° C. with stirring to dissolve. A normal hexane solution (a) of synthetic polyisoprene having a concentration of 15% by weight was prepared.

(Preparation of emulsifier aqueous solution (b1))
An emulsifier aqueous solution (b1) having a potassium rosinate concentration of 1.2% by weight was prepared by mixing potassium rosinate as a fatty acid-based emulsifier with water at a temperature of 60 ° C.

(Production of synthetic polyisoprene latex)
Then, using the normal hexane solution (a) of the synthetic polyisoprene prepared above and the aqueous solution of the emulsifier (b1), a synthetic polyisoprene latex was produced using the emulsifying apparatus shown in FIG.

Specifically, the normal hexane solution (a) of the synthetic polyisoprene prepared as described above is stored in the polymer tank 10 while being heated to 60 ° C., and is stored in the emulsifier tank 20 as described above. The prepared emulsifier aqueous solution (b1) is stored while being heated to 60 ° C., and these are stored in a line as a premixing device so that the weight ratio of “synthetic polyisoprene”: “emulsifier” becomes 10: 1. After premixing with a mixer, the mixture was continuously supplied to the mixing device 30 to continuously obtain an emulsion (the ratio of normal hexane in the emulsion was 37.7% by weight). The emulsified liquid was continuously discharged to a closed storage tank 40 in which the valves other than the connection pipe to the mixing device 30 were closed. As the mixing device 30, a homogenizer (trade name "Milder", manufactured by Taiheiyo Kiko Co., Ltd.) was used. Further, before the emulsified liquid was discharged from the mixing device 30, the pressure of the storage tank 40 in a closed state was 0 MPa (gauge pressure).

Next, when the amount of the emulsion in the storage tank 40 becomes 56% by volume with respect to the volume of the storage tank 40, the transfer of the emulsion from the mixing device 30 to the storage tank 40 is stopped, and the mixing is stopped. After closing the valve of the connection pipe to the device 30 and starting stirring by the stirring blade 50, steam is flowed into a jacket (not shown) provided outside the storage tank 40 to warm the emulsion. Started. At the start of heating, the pressure valve connected to the upper part of the condenser 70 is opened, the air in the storage tank 40 is removed, and after the condensation of normal hexane vapor by the condenser 70 is confirmed, the pressure valve is closed. The system composed of the storage tank 40, the distillation pipe 60 and the condenser 70 was a closed system which was closed from the outside air. In the present embodiment, the temperature of the emulsion is raised to 85 ° C. by heating with steam, and the pressure inside the storage tank 40 when the temperature of the emulsion reaches 85 ° C. is 0.08 MPa (gauge pressure). Met.
In this example, the distillation of normal hexane from the emulsion was continued under the conditions that the temperature of the emulsion was 85 ° C. and the pressure inside the storage tank 40 was 0.08 MPa (gauge pressure).

During the distillation of normal hexane, the amount of normal hexane collected by the condenser 70 was measured every hour, and the content of normal hexane in the emulsion was reduced to 100% by weight of the synthetic polyisoprene in the emulsion. On the other hand, when it was determined that the concentration became 100 ppm by weight or less, it was determined that the distillation of normal hexane was completed, and the distillation of normal hexane under pressurized conditions was terminated. In Example 1, the organic solvent distillation time, which is the time from the start of normal hexane vapor aggregation in the condenser 70 to the end of normal hexane distillation, was 9 hours (described later). In Examples 1 to 4 and Comparative Examples 1 and 2, the organic solvent distillation time was measured in the same manner.) Also, during this time, when the foam surface height due to the foaming of the emulsion in the storage tank 40 was observed, the height was 72% of the storage tank volume (maximum foam surface height: 72%) at the highest time. there were. Further, in Example 1, after the distillation of normal hexane was completed, the ratio of the synthetic polyisoprene adhered to the wall surface of the storage tank 40 was reduced to 100% by weight of the total amount of the synthetic polyisoprene contained in the emulsion. In contrast, the content was 1.3% by weight, and the volume average particle diameter of the obtained synthetic polyisoprene latex was 1.09 μm.

<Example 2>
In the same manner as in Example 1, except that the heating temperature of the emulsion was changed from 85 ° C. to 78 ° C. by heating with steam when normal hexane was distilled off in the storage tank 40. N-hexane was distilled off from the mixture. In Example 2, when the temperature of the emulsion was set at 78 ° C., the pressure inside the storage tank 40 was 0.06 MPa (gauge pressure). Table 1 shows the results.

<Example 3>
Instead of normal hexane, normal pentane (boiling point: 36 ° C.) is used, and when the normal pentane is distilled off in the storage tank 40, the emulsion is heated to 85 ° C. by heating with steam. The normal pentane was distilled off from the emulsion in the same manner as in Example 1 except that the temperature was changed to 67 ° C. In Example 3, when the temperature of the emulsion was set at 67 ° C., the pressure inside the storage tank 40 was 0.04 MPa (gauge pressure). Table 1 shows the results.

<Example 4>
A styrene-isoprene-styrene copolymer (trade name “Quintac 3620”, manufactured by Zeon Corporation, described as “SIS” in Table 1) was used instead of synthetic polyisoprein, and cyclohexane was used instead of normal hexane. (Boiling point: 80 ° C.) Except for using, in the same manner as in Example 1, an emulsified liquid was obtained, and when the cyclohexane was distilled off in the storage tank 40, the emulsified liquid was heated by steam. Cyclohexane was distilled off from the emulsion in the same manner as in Example 1 except that the heating temperature was changed from 85 ° C. to 82 ° C. In Example 4, when the temperature of the emulsion was 82 ° C., the pressure inside the storage tank 40 was 0.07 MPa (gauge pressure). Table 1 shows the results.

<Comparative Example 1>
When the normal hexane is distilled off in the storage tank 40, the heating temperature of the emulsion is changed from 85 ° C. to 60 ° C. by heating with steam, and the pressure in the storage tank 40 is set to −0. Normal hexane was distilled off from the emulsion in the same manner as in Example 1 except that the pressure was reduced under a pressure of 02 MPa (gauge pressure). In Comparative Example 1, a pressure reducing pump was connected to the downstream side of the condenser 70, and the pressure in the storage tank 40 was adjusted to −0.02 MPa (gauge pressure) by reducing the pressure with the pressure reducing pump. Table 1 shows the results.

<Comparative Example 2>
Except that cyclohexane was used instead of normal hexane, an emulsion was obtained in the same manner as in Example 1, and when the cyclohexane was distilled off in the storage tank 40, the emulsion was heated by steam. Except that the heating temperature was changed from 85 ° C. to 86 ° C. and the pressure in the storage tank 40 was reduced under a reduced pressure condition of −0.02 MPa (gauge pressure), Of cyclohexane was distilled off. In Comparative Example 2, a pressure reducing pump was connected to the downstream side of the condenser 70, and the pressure in the storage tank 40 was adjusted to −0.02 MPa (gauge pressure) by reducing the pressure with the pressure reducing pump. In Comparative Example 2, foaming of the emulsion was intense, and a part of the emulsion passed through the distillation pipe 60 to the condenser 70, and the cyclohexane could not be continuously distilled. Was.

As shown in Table 1, when the pressure inside the storage tank 40 was increased to 0.02 MPa (gauge pressure) or more and the organic solvent was distilled off from the emulsion, the wall of the polymer tank 40 was removed. The evaporation time of the organic solvent could be shortened while keeping the adhesion to the solvent small, so that the production in a short time was possible while realizing a high yield (Examples 1 to 4).

On the other hand, when the organic solvent is distilled off from the emulsion by reducing the pressure in the storage tank 40 at a temperature of 60 ° C., the maximum foam surface height is increased to 90% by volume, and the organic solvent is removed. As a result, the solvent distillation time was prolonged, and the adhesion of the polymer to the wall surface of the tank 40 was increased (Comparative Example 1).
Further, when the temperature is raised to 86 ° C. and the pressure in the storage tank 40 is reduced to thereby evaporate the organic solvent from the emulsion, the foaming of the emulsion is intense, and a part of the emulsion is It entered into the condenser 70 from the storage tank 40 (the maximum foam surface height exceeded 100%), and the organic solvent could not be continuously distilled off (Comparative Example 2).

Claims

A polymer latex comprising a step of distilling off an organic solvent from an emulsion obtained by mixing a polymer solution or dispersion obtained by dissolving or dispersing the polymer in an organic solvent and an aqueous solution of an emulsifier. A manufacturing method,
A method for producing a polymer latex, wherein the organic solvent is distilled off from the emulsion in a vessel adjusted to a pressure condition of 0.02 MPa or more at a gauge pressure.
(4) The method for producing a polymer latex according to (1), wherein the content of the organic solvent in the emulsion before the organic solvent is distilled off is 30 to 60% by weight.
(3) The method for producing a polymer latex according to (1) or (2), wherein the organic solvent is distilled off from the emulsion in a container adjusted to a gauge condition of 0.02 to 0.18 MPa.
4. The method for producing a polymer latex according to any one of claims 1 to 3, wherein the organic solvent is distilled off from the emulsion at a temperature equal to or higher than the boiling point of the organic solvent.
(5) The method for producing a polymer latex according to any one of (1) to (4), wherein the organic solvent is an organic solvent selected from cyclohexane, normal hexane, cyclopentane and normal pentane.
The method for producing a polymer latex according to any one of claims 1 to 5, wherein the organic solvent is distilled off by heating by a method of introducing steam under pressure into a jacket provided in the container. .
(7) The method for producing a polymer latex according to any one of (1) to (6), wherein the polymer is a synthetic polyisoprene and / or a styrene-isoprene-styrene copolymer.
8. The emulsion according to claim 1, wherein the content of the emulsifier in the emulsion before the organic solvent is distilled off is 0.1 to 30 parts by weight based on 100 parts by weight of the polymer. A method for producing a polymer latex.