Method for producing purified polymer emulsion and method for removing volatile organic substances

Abstract

To provide a purified polymer emulsion by removing volatile organic substances such as a residual monomer, solvent, and the like remaining in a polymer emulsion obtained by emulsion polymerization.SOLUTION: Provided is a method for producing a purified polymer emulsion, comprising adding zeolite having a SiO2 / Al2O3 molar ratio of 35 or more and an average pore diameter of 6Å to 12Å to a polymer emulsion containing volatile organic substances.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing a purified polymer emulsion and to a method for removing volatile organic substances. [Background technology]

[0002] Polychloroprene latex has good properties such as mechanical strength, weather resistance, heat resistance and chemical resistance, and is therefore used in various fields such as dip molding products, fiber treatment agents, paper processing agents, pressure sensitive adhesives, adhesives, elastic asphalt (modified asphalt) and elastic cement.

[0003] Such polychloroprene latexes have been prepared by emulsion polymerization. Generally, polymer emulsions obtained by emulsion polymerization contain volatile organic substances including low molecular weight components such as monomers and solvents used in washing.

[0004] Such volatile organic substances are considered to be causative substances of secondary particulate matter, such as photochemical oxidants and suspended particulate matter, and are a cause of health hazards, such as sick house syndrome and hypersensitivity to chemicals, as well as a cause of deterioration of the working environment. In addition, regulations on emissions of volatile organic substances are being strengthened under the Air Pollution Control Act, requiring businesses to further reduce their emissions.

[0005] Conventionally, methods for removing remaining volatile organic substances have generally been used, such as steam stripping under reduced pressure (Patent Document 1) or removing remaining monomers by adjusting reaction conditions such as the conditions for adding catalyst and polymerization initiator and the pressure (Patent Document 2). Steam stripping has issues such as precipitation from emulsion due to steam, and there is also a limit to the reduction of volatile organic substances when adjusting reaction conditions.

[0006] It is also known that diatomaceous earth is used as a method for purifying polymer emulsions (JP Patent Publication No. 3-65820), but this relates to a method for filtering out fine coagulum and is not intended to remove volatile organic substances. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent No. 2,467,769 [Patent Document 2] JP 2003-82006 A [Patent Document 3] Special Publication No. 3-65820 Summary of the Invention [Problem to be solved by the invention]

[0008] In the prior art, no suitable method was known for reducing volatile organic compounds in polymer emulsions. In addition, in homogeneous solutions, removal of water, metal ions, and volatile organic substances after reaction using adsorbents such as activated carbon, mesoporous silica, and zeolite has been considered, but has not been considered in polymer emulsions. The reason is that when a polymer is finely dispersed in water using a surfactant, as in polymer emulsions, if the adsorbent adsorbs water, which is a continuous layer, a situation occurs in which there is a temporary lack of water near the adsorbent, and the polymer precipitates as aggregates from near the adsorbent. In addition, in addition to the volatile organic substances that are the target substances, the adsorbent also adsorbs the emulsifiers and stabilizers contained in the emulsion at the same time, which is thought to be one of the reasons why the polymer emulsion has not been considered, as it destabilizes the polymer emulsion.

[0009] Therefore, an object of the present invention is to provide a method for removing volatile organic substances present in a polymer emulsion, which suppresses denaturation of the polymer emulsion due to thermal history, etc., and does not cause destabilization of the polymer emulsion due to adsorption of surfactants, etc., even under conditions in which an adsorbent is used. [Means for solving the problem]

[0010] Under these circumstances, the present inventors conducted extensive research and discovered that a purified polymer emulsion can be produced by adding a specific zeolite to a polymer emulsion, thereby completing the present invention.

[0011] That is, the present invention is configured as follows. [1] A method for producing a purified polymer emulsion, comprising the steps of: SiO in polymer emulsion containing volatile organic substances 2 / Al 2 O 3 A method for producing a purified polymer emulsion, comprising adding a zeolite having a molar ratio of 35 or more and an average pore diameter of 6 Å or more and 12 Å or less. [2] The method for producing a purified polymer emulsion according to [1], wherein the polymer emulsion is a polychloroprene latex. [3] The method for producing a purified polymer emulsion according to [1] or [2], wherein the concentration of volatile organic substances contained in the purified polymer emulsion is 150 ppm by mass or less based on the solid content mass of the purified polymer emulsion. [4] The method for producing a purified polymer emulsion according to any one of [1] to [3], wherein the volatile organic substance is a residual monomer from a polymerization reaction in the production of the polymer emulsion. [5] The method for producing a purified polymer emulsion according to any one of [1] to [4], wherein the volatile organic substances are derived from a washing solvent in a production process of the polymer emulsion. [6] The method for producing a purified polymer emulsion according to any one of [1] to [5], wherein the zeolite is in the form of a powder or pellets. [7] The method for producing a purified polymer emulsion according to any one of [1] to [6], wherein the zeolite is 3 parts by mass or more per 100 parts by mass of the polymer emulsion. [8] The method for producing a purified polymer emulsion according to any one of [1] to [7], wherein the zeolite is 4 parts by mass or more per 100 parts by mass of the solid content of the treated amount of the polymer emulsion. [9] A method for producing a purified polymer emulsion according to any one of [1] to [8], comprising a step of removing the zeolite.

[10] For polymer emulsions containing low molecular weight compounds as volatile organic substances, SiO 2 / Al 2 O 3 A method for removing volatile organic substances from a polymer emulsion, comprising contacting the polymer emulsion with a zeolite having a ratio of 35 or more and an average pore size of 6 Å or more and 12 Å or less.

[11] The method for removing volatile organic substances in a polymer emulsion according to

[10] , wherein the polymer emulsion is a polychloroprene latex.

[12] A method for removing volatile organic substances in a polymer emulsion according to

[10] or

[11] , comprising adsorbing and removing the volatile organic substances chloroprene monomer and toluene.

[13] The method for removing volatile organic substances in a polymer emulsion according to

[10] to

[12] , wherein the zeolite is in the form of a powder or pellets.

[14] The method for removing volatile organic substances in a polymer emulsion according to any one of

[10] to

[13] , wherein the zeolite is 3 parts by mass or more per 100 parts by mass of the polymer emulsion. Effect of the Invention

[0012] The removal of volatile organic substances by using a specific zeolite as an adsorbent as in the present invention does not involve a heating step or chemical reaction, and is therefore an excellent method for suppressing polymer denaturation, and is also excellent in that it can suppress fluctuations in solid concentration when applied to polymer emulsions. For these reasons, it can be said to be an advantageous removal method.

[0013] Therefore, according to the present invention, it is possible to provide a method for producing a purified polymer emulsion and a method for removing volatile organic substances, which are capable of efficiently removing volatile organic substances while suppressing precipitation of aggregates from the emulsion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The method for producing a purified polymer emulsion and the method for removing volatile organic substances according to this embodiment will be described below. In this specification, the term "purified polymer emulsion" refers to a polymer emulsion produced through the steps described below, and in which the amount of volatile organic substances has been reduced by the steps.

[0015] In this specification, the term "crude polymer emulsion" or simply "polymer emulsion" refers to a polymer emulsion that has not undergone the steps described below or is in the middle of undergoing the steps.

[0016] Also, in this specification, "removal" means removing at least a portion of the residual volatile materials in the polymer emulsion. The "solid content" of a polymer emulsion includes various additives such as an emulsifier in addition to the polymer, and corresponds to components other than the dispersion medium.

[0017] The method for producing a purified polymer emulsion of the present embodiment includes adding SiO 2 / Al 2 O 3 The method is characterized by reducing the amount of volatile organic substances contained by adding zeolite with a ratio of 35 or more and an average pore diameter of 6 Å to 12 Å.

[0018] [Polymer emulsion] A polymer emulsion is an emulsion in which a polymer is stably dispersed in a dispersion medium. The polymer is not particularly limited, but includes polychloroprene, polyisoprene, natural rubber (NR), polybutadiene rubber (BR), nitrile rubber (NBR), hydrogenated or partially hydrogenated nitrile rubber (HNBR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), butyl rubber (IIR), polychloroprene (CR), ethylene propylene rubber (EPDM), chlorinated polyethylene (CM), and chlorosulfonated rubber (CSM). Conjugated dienes such as polychloroprene and polyisoprene are preferred, and polychloroprene is more preferred. Polychloroprene may be a homopolymer consisting of only chloroprene as a monomer, or a copolymer of chloroprene and other monomers. Such an emulsion of polychloroprene homopolymer and polychloroprene copolymer is sometimes called polychloroprene latex.

[0019] In the case of the polychloroprene copolymer, the other monomers copolymerized with chloroprene are not particularly limited, and examples thereof include 2,3-dichloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, acrylic acid and its esters, methacrylic acid and its esters, etc. These may be used alone or in combination of two or more.

[0020] The monomers constituting the copolymer preferably contain chloroprene as a main component, and the amount of chloroprene in the total content of all monomers constituting the copolymer (100% by mass) is preferably 70.0 to 99.9% by mass, more preferably 75.0 to 99.8% by mass, and even more preferably 80.0 to 99.7% by mass.

[0021] The dispersion medium is not particularly limited as long as it forms an emulsion, but typically includes water, methanol, ethanol, etc., and is preferably water. The solid content concentration of the polymer emulsion is not particularly limited as long as a stable dispersion state is maintained, and is preferably 40 to 70 mass %, more preferably 42 to 65 mass %, and further preferably 45 to 62 mass %.

[0022] In this specification, the solid content concentration of the polymer emulsion is the ratio of the mass of the dry residue to the mass of the emulsion before drying when the polymer emulsion is heated and dried at 140° C. for 25 minutes.

[0023] The synthesis method of the polymer emulsion in this embodiment is not particularly limited, and the production method of this embodiment can be applied to polymer emulsions obtained by known synthesis methods. For example, in the case of polychloroprene latex, it can be synthesized by the methods described in JP-A-2007-106994 and JP-A-2019-044116.

[0024] As a method for synthesizing the polymer emulsion, emulsion polymerization can be preferably adopted. In particular, aqueous emulsion polymerization can be adopted industrially. As an emulsifier in the emulsion polymerization method, for example, rosin acid soap can be used. In particular, from the viewpoint of coloring stability, it is preferable to use sodium and / or potassium salt of disproportionated rosin acid. The amount of rosin acid soap used is preferably 3 to 8 parts by mass per 100 parts by mass of monomer. Within this range, sufficient emulsification can be achieved, so that polymerization heat generation can be easily controlled and no aggregates are generated, making it possible to finally obtain a product with excellent appearance.

[0025] Therefore, polymer emulsions contain a dispersion medium and an emulsifier in addition to the polymer. They may also contain copper sulfate used during polymerization and an alkali component (metal hydroxide) used during emulsification. They may also contain a polymerization terminator such as phenothiazine, para-t-butylcatechol, hydroquinone, hydroquinone monomethyl ether, or diethylhydroxylamine to adjust the molecular weight and distribution of the polymer, and stabilizers such as acid acceptors and antioxidants to suppress deterioration due to oxygen.

[0026] [Volatile organic substances] Examples of volatile organic substances contained in the polymer emulsion include unreacted monomers (residual monomers) in the polymerization reaction in producing the polymer emulsion, and organic solvents (residual organic solvents) used in the process of producing the polymer emulsion.

[0027] The residual monomers are unreacted monomers among the monomers constituting the above-mentioned polymer emulsion, and are mainly chloroprene monomers, which are the main component of chloroprene polymers. From the viewpoint of maintaining the quality and properties of the polymer emulsion in a good condition, it is preferable to remove these residual monomers. In particular, chloroprene monomers are the residual monomers that can be contained in the largest amount as the main component, and it is preferable to remove as much of them as possible from the emulsion.

[0028] Examples of the residual organic solvent include a solvent used as a reaction solvent when dissolving a monomer, a solvent contained in various additives, and a cleaning solvent used in a plant when separating and cleaning impurities from a product. Examples of the residual organic solvent include aliphatic hydrocarbon solvents such as pentane, hexane, heptane, etc.; alicyclic hydrocarbon solvents such as cyclopentane, cyclohexane, methylcyclohexane, etc.; alcohol solvents such as methanol, ethanol, isopropanol, etc.; aromatic hydrocarbon solvents such as toluene, xylene, etc.; ether solvents such as tetrahydrofuran, diethyl ether, cyclopentyl methyl ether, 4-methylcyclohydropyran, etc.; ester solvents such as ethyl acetate, propyl acetate, butyl acetate, etc.; and ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, etc.

[0029] Of these, toluene is used for the purposes of dispersing the various additives described above and for cleaning the production equipment, and if it remains, it will have the effect of imparting an odor to the purified polymer emulsion, so it is desirable to remove it.

[0030] The concentration of volatile organic substances contained in the crude polymer emulsion is not particularly limited, and is preferably 300 to 5000 ppm by mass, more preferably 400 to 3000 ppm by mass, and further preferably 500 to 1000 ppm by mass, based on the solid content mass of the crude polymer emulsion.

[0031] The manufacturing method of the present embodiment is advantageously applied to further reduce the concentration of the volatile organic substances when the concentration is 300 ppm by mass or more. Also, when the concentration is 5000 ppm by mass or less, the concentration can be further reduced efficiently.

[0032] The concentration of volatile organic substances contained in the crude polymer emulsion is not particularly limited, and is preferably 150 to 10,000 ppm by mass, more preferably 175 to 5,000 ppm by mass, and even more preferably 200 to 1,000 ppm by mass, based on the total mass of the crude polymer emulsion including the solvent.

[0033] [Zeolite] The SiO of the zeolite used in the production method of this embodiment 2 / Al 2 O 3 The ratio is 35 or more, preferably 100 or more, and more preferably 200 or more. 2 / Al 2 O 3 A ratio of 35 or more is preferable since it makes it possible to selectively adsorb chloroprene monomer and toluene, which are major organic volatile components contained in polymer emulsions, particularly chloroprene latexes.

[0034] Zeolite SiO 2 / Al 2 O 3 The ratio is preferably 10,000 or less, more preferably 5,000 or less, and even more preferably 3,000 or less. The SiO 2 / Al 2 O 3 If the ratio is 10,000 or less, it is possible to avoid destabilization due to a decrease in the pH of the polymer emulsion, which is preferable.

[0035] The average pore diameter of the zeolite is 6 Å or more, more preferably 8 Å or more. If the average pore diameter of the zeolite is 6 Å or more, it is preferable because it can adsorb chloroprene monomers, which are the main organic volatile components contained in polymer emulsions, particularly chloroprene latex. The average pore diameter of the zeolite is 12 Å or less, preferably 10 Å or less. If the average pore diameter of the zeolite is 12 Å or less, it is preferable because it does not adsorb components other than organic volatile components such as surfactants, and therefore the stability of the emulsion is maintained.

[0036] In general, zeolite is a general term for crystalline aluminosilicate. The zeolite used in the present embodiment may be either natural or synthetic, but is preferably synthetic.

[0037] In general, the basic unit of the crystal structure (also called the framework structure) of zeolite is a tetrahedron consisting of four oxygen atoms surrounding a silicon atom or an aluminum atom, and these are connected in three dimensions to form the crystal structure.

[0038] The crystal structure of the zeolite used in this embodiment is not particularly limited, and examples thereof include various crystal structures represented by a structure code consisting of three letters of the alphabet defined by the International Zeolite Association. Examples of the structure code include the codes LTA, FER, MWW, MFI, MOR, LTL, FAU, and BEA. In addition, when a suitable embodiment of the crystal structure used in this embodiment is expressed by the name of the crystal structure, it is preferably at least one type selected from the group consisting of A type, X type, β type, Y type, L type, ZSM-5 type, MCM-22 type, ferrierite type, and mordenite type. Furthermore, monodenite, arunasite, sodalite group aluminosilicate, clinobutyrolite, erionite, and chabazite can also be used. Among these, ZSM-5 type zeolite is preferred.

[0039] The zeolite may be in the form of a powder or may be formed into pellets. The average particle size of the zeolite powder used in this embodiment is not particularly limited, and is preferably 20 μm or less, more preferably 15 μm or less, and more preferably 10 μm or less. The particle size of the zeolite is preferably 0.1 μm or more. If it is in this range, the zeolite powder will not aggregate and will be easily separated from the emulsion.

[0040] The zeolite powder used in this embodiment may be surface-treated with a surface treatment agent, and the surface treatment is preferably at least any one of a silane coupling agent treatment, an isocyanate compound treatment, a thiol compound treatment, an acid compound treatment, an alcohol compound treatment, and an epoxy compound treatment.

[0041] The shape of the pelletized zeolite is not particularly limited as long as it is obtained by molding the powder into pellets under known conditions. The zeolite is preferably contacted in an amount of 3 parts by mass or more, more preferably 6 parts by mass or more, per 100 parts by mass of the crude polymer emulsion, in order to efficiently remove volatile organic substances.

[0042] The zeolite is preferably contacted in an amount of 4 parts by mass or more, more preferably 6 parts by mass or more, and even more preferably 8 parts by mass or more, per 100 parts by mass of the solid content in the crude polymer emulsion. The zeolite is preferably contacted in an amount of 30 parts by mass or less, per 100 parts by mass of the solid content in the crude polymer emulsion. If the amount is within this range, volatile organic substances can be efficiently removed.

[0043] [Processing method and device] The temperature of the polymer emulsion when the zeolite is contacted with the polymer emulsion is not particularly limited, but is preferably from 10° C. to 60° C., more preferably from 15° C. to 50° C., and even more preferably from 20° C. to 40° C. If the temperature of the polymer emulsion when the zeolite is contacted with the polymer emulsion is from 10° C. to 60° C., no energy is required to heat the polymer emulsion, which is preferable.

[0044] The time for contacting the zeolite with the polymer emulsion is not particularly limited, but in the case of a batch apparatus, it is preferably from 0.1 to 10 hours, more preferably from 1 to 8 hours, and even more preferably from 2 to 5 hours. If the time for contacting the zeolite with the polymer emulsion is from 1 to 10 hours, the size of the reaction vessel becomes appropriate, which is preferable.

[0045] The pressure when the zeolite is brought into contact with the polymer emulsion is not particularly limited, and reduced pressure or pressurized pressure can be used, but normal pressure (atmospheric pressure) is more preferable. The device for contacting the zeolite with the polymer emulsion is not particularly limited, but any device capable of removing volatile organic substances from the latex under the above-mentioned atmospheric pressure and temperature conditions may be used. Either a batch type or a continuous type device may be used. For example, stirring in a container such as a tank, mixing in a pipe, countercurrent contact using a stripping tower, etc. are included. Among these, stirring in a container such as a tank is preferred from the viewpoints of ease of maintenance and expansion of the device, cost, etc.

[0046] In the production method of this embodiment, other methods such as distillation, adsorption, spraying, etc. may be used in combination to remove volatile organic substances from the polymer emulsion, as long as the effect of this embodiment of suppressing precipitation of aggregates from the polymer emulsion is not impaired.

[0047] The zeolite is separated and recovered from the polymer emulsion after the above steps by a solid-liquid separation means to produce a purified polymer emulsion. The solid-liquid separation means is not particularly limited, and examples thereof include filtration and decantation.

[0048] According to this embodiment, the volatile organic substances in the polymer emulsion are removed, and the concentration of the volatile organic substances is reduced. The concentration of the volatile organic substances is preferably reduced to less than 300 ppm by mass, more preferably 250 ppm by mass or less, even more preferably 200 ppm by mass or less, and even more preferably 100 ppm by mass or less, based on the solid content of the purified polymer emulsion.

[0049] The recovered zeolite can be reused by heating it at 150°C or higher to regenerate it. According to this embodiment, a polymer emulsion containing a low molecular weight compound as a volatile organic substance is mixed with SiO 2 / Al 2 O 3 Also provided is a method for removing volatile organic substances from a polymer emulsion by contacting with a zeolite having a ratio of 35 or greater and an average pore size of 6 Å or greater and 12 Å or less.

[0050] In this removal method, polychloroprene latex is preferably used as the polymer emulsion, and volatile organic substances such as chloroprene monomer and toluene can be adsorbed and removed. As described above, the zeolite used is preferably in the form of particles or pellets. Furthermore, the amount of the zeolite is preferably 3 parts by mass or more, more preferably 6 parts by mass or more, per 100 parts by mass of the polymer emulsion to be treated. EXAMPLES

[0051] The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples in any way.

[0052] [Quantitative analysis of volatile organic substances] Chloroprene and toluene, which are residual monomers contained in the polychloroprene latex, were regarded as volatile organic substances and were measured by high performance liquid chromatography under the following measurement conditions.

[0053] <Measurement conditions> Measurement sample: A chloroprene extract obtained by adding and mixing 20 g of cyclohexane (manufactured by Junsei Chemical Co., Ltd.) to 0.1 g of latex and a solution obtained by diluting butyl propionate 100 times (by mass) with cyclohexane was mixed at a mass ratio of 9:1. Measurement equipment: High-performance liquid chromatograph; Shimadzu Corporation, "Prominence (registered trademark)" Detector: UV 220nm Column: Showa Denko K.K., "Shodex (registered trademark) Asahipak (registered trademark) ODP-50 4D" Column temperature: 40℃ Eluent: acetonitrile / water = 6 / 4 (volume ratio) ·Flow rate: 0.8mL / min ·Injection volume: 10μL Internal standard: Butyl propionate

[0054] [SiO2 / Al 2 O 3 ratio] Zeolite SiO 2 / Al 2 O 3 The ratio was measured using a nuclear magnetic resonance measurement device (JNM-ECZR600, manufactured by JEOL Ltd.). 29 Si- and 27 The molar ratio of Si / Al was determined by Al-MAS (magic angle sample spinning)-NMR, and SiO 2 / Al 2 O 3 The ratio was calculated in terms of molar ratio.

[0055] [Average pore diameter] Calculated in accordance with JIS Z 8831-3:2010.

[0056] [Confirmation of aggregate formation] After removing the chloroprene latex from the purified polymer emulsion by filtration using a metal net with an 80 mesh (opening size 0.177 mm), the surface of the filter cake remaining on the metal net was observed under a microscope (Keyence Corporation, model number: VH-6300) at 50x magnification to confirm the presence or absence of aggregates.

[0057] [Synthesis example of chloroprene polymer latex] A 60 L reactor was charged with 20.0 kg of 2-chloro-1,3-butadiene (chloroprene) (manufactured by Tokyo Chemical Industry Co., Ltd.) as a monomer, 11.2 kg of pure water, 340 g of disproportionated rosin acid (manufactured by Arakawa Chemical Industries, Ltd., "R-300"), 10.0 g of n-dodecyl mercaptan (manufactured by Tokyo Chemical Industry Co., Ltd.), 1.1 kg of potassium hydroxide (manufactured by Junsei Chemical Industry Co., Ltd.), and 2,400 g of a sodium salt of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Corporation).

[0058] These raw materials were emulsified to convert the disproportionated rosin acid into rosin soap, and then potassium persulfate (manufactured by Mitsubishi Gas Chemical Co., Inc.) was added as an initiator to carry out polymerization at 45°C under a nitrogen atmosphere. After 6 hours, it was confirmed that the polymerization conversion rate had reached 90%, and an emulsion in which phenothiazine was dissolved and emulsified in toluene was immediately added to terminate the polymerization.

[0059] Next, residual monomers were removed by steam distillation to obtain a chloroprene polymer latex (solid content concentration: 59% by mass), in which the chloroprene monomer concentration was 282 ppm by mass and the toluene concentration was 482 ppm by mass.

[0060] [Example 1] 100 g of the chloroprene polymer latex synthesized in Synthesis Example 1 was placed in a reaction vessel, the liquid temperature was adjusted to 23° C., 3 g of zeolite (Union Showa Co., Ltd., HiSiv3000, ZMS-5 type) was added, and the mixture was stirred with a stirring rod at 600 rpm for 3 hours. After this process, the chloroprene monomer concentration in the obtained purified polymer emulsion was 24 ppm by mass, and the toluene concentration was 275 ppm by mass.

[0061] [Examples 2 to 4, Comparative Examples 1 to 3] The same procedure as in Example 1 was carried out, except that the type, amount, and treatment time of the adsorbent were as shown in Table 1.

[0062] [Table 1]

[0063] Monomer: Chloroprene Monomer SiO of the Example 2 / Al 2 O 3 When a zeolite having a molar ratio of 35 or more and an average pore size of 6-9 Å is used, the chloroprene monomer and toluene can be removed well, and the emulsion does not aggregate. On the other hand, even when a zeolite having an average pore size of 6-9 Å is used as in Comparative Example 2, the SiO 2 / Al 2 O 3The efficiency of removing chloroprene monomer and toluene was poor when the molar ratio was less than 35. Furthermore, when zeolites having different average pore sizes were used as in Comparative Examples 1 and 3, the emulsion flocculated.

Claims

1. 1. A method for producing a purified polymer emulsion, comprising: Polymer emulsions that contain volatile organic substances and are polychloroprene latex SiO 2 / Al 2 O 3 The method is characterized in that a zeolite having a molar ratio of 35 or more and an average pore diameter of 6 Å to 12 Å is added. A method for producing a purified polymer emulsion.

2. 2. The method for producing a purified polymer emulsion according to claim 1, wherein the concentration of volatile organic substances contained in the purified polymer emulsion is 300 ppm by mass or less based on the solid content mass of the purified polymer emulsion.

3. 3. The method for producing a purified polymer emulsion according to claim 1 or 2, wherein the volatile organic substances are residual monomers from a polymerization reaction in the production of the polymer emulsion.

4. 3. The method for producing a purified polymer emulsion according to claim 1, wherein the volatile organic substances are derived from a washing solvent in a process for producing the polymer emulsion.

5. The method for producing a purified polymer emulsion according to any one of claims 1 to 4, wherein the zeolite is in the form of a powder or pellets.

6. The method for producing a purified polymer emulsion according to any one of claims 1 to 5, wherein the zeolite is present in an amount of 3 parts by mass or more per 100 parts by mass of the polymer emulsion.

7. The method for producing a purified polymer emulsion according to any one of claims 1 to 6, wherein the zeolite is used in an amount of 4 parts by mass or more per 100 parts by mass of solids in a processing amount of the polymer emulsion.

8. A method for producing the purified polymer emulsion according to any one of claims 1 to 7, comprising a step of removing the zeolite.

9. A polymer emulsion containing polychloroprene latex as a volatile organic substance, and SiO 2 / Al 2 O 3 A method for removing volatile organic substances from a polymer emulsion, comprising contacting the polymer emulsion with a zeolite having a ratio of 35 or more and an average pore size of 6 Å or more and 12 Å or less.

10. 10. The method for removing volatile organic substances in a polymer emulsion according to claim 9, wherein the volatile organic substances include chloroprene monomer and toluene.

11. The method for removing volatile organic substances in a polymer emulsion according to claim 9 or 10, wherein the zeolite is in the form of a powder or pellets.

12. 12. The method for removing volatile organic substances in a polymer emulsion according to claim 9, wherein the zeolite is present in an amount of 3 parts by mass or more per 100 parts by mass of the polymer emulsion.

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