JP4980676B2 - Polymer recovery method - Google Patents

Description

  The present invention relates to a method for efficiently recovering a polymer containing an additive from a polymer latex.

Rubber-reinforced resins represented by acrylonitrile-butadiene-styrene resin (ABS resin) are generally produced by emulsion polymerization. In this polymerization method, the polymer is recovered from the obtained latex. In order to do so, it is necessary to perform dehydration, washing, and drying steps after depositing with a coagulant to form a slurry. When the polymer is recovered by this method, the latex is coagulated by supplying the polymer latex and the coagulant aqueous solution to a coagulation tank filled with hot water and stirring in the coagulation tank. For this reason, since the recovered polymer particles have a wide particle size distribution and a large amount of fine particles exist, (1) the dehydration process in the dehydration process is poor, and (2) the fine particles are clogged in the separation / drying process. Productivity decreases, (3) Equipment for preventing dust explosion caused by fine powder particles is required, (4) Fine powder particles are scattered when put into an extruder, and powder is bridging in the hopper There are problems such as not feeding into the extruder.
For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2003-321547), a polymer latex and a coagulant liquid are mixed to form a coagulated cream, and then poured into hot water through pores and stirred / solidified / divided. Has proposed a method for recovering a polymer having a small amount of fine particles.
In these polymers, various additives are added and mixed depending on the required performance, but depending on the type of additive, it is not sufficiently dispersed, so the amount added must be increased or dispersed. Problems such as poor appearance due to defects may occur.
JP 2003-321547 A

  An object of the present invention is to provide a method for efficiently recovering a polymer containing an additive from a polymer latex.

  Polymer particles containing almost no fine powder can be collected, and the polymer containing an additive that does not cause a problem during powder handling can be efficiently collected.

The present invention provides a polymer latex (in terms of solid content) 99.9 to 40% by weight and a synthetic latex containing an additive dispersion (in terms of solid content) 0.1 to 60% by weight. When recovering the coalescence, the mixed latex is mixed with an aqueous solution of a coagulant to make a paste, and then extruded from the pores into warm water to coagulate, and then the additive for synthetic resin is added from the polymer latex. A method for recovering a contained polymer, wherein as the polymer latex, one or more of a rubber-like polymer latex, a graft copolymer latex and a hard resin polymer latex is used as a hydrophilic group. The present invention provides a method for recovering a polymer, which is emulsion-polymerized in the presence of a surfactant having a sodium salt and / or a potassium salt .

The present invention will be described in detail below.
Examples of polymer latex to which the recovery method of the present invention is applied include polymer latex produced by emulsion polymerization. For example, rubbery polymer latex such as butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), acrylic rubber, etc., acrylonitrile, styrene, α-methylstyrene, Graft polymer latex obtained by graft polymerization of a copolymerizable vinyl monomer such as methyl methacrylate, or polystyrene or styrene-acrylonitrile copolymer obtained by emulsion polymerization of the vinyl monomer. Examples thereof include, but are not limited to, hard resin polymer latexes such as styrene-methyl methacrylate copolymer and α-methylstyrene-acrylonitryl copolymer.

The surfactant used in the emulsion polymerization of the rubber- like polymer latex, the graft polymer latex and the hard resin polymer latex used in the present invention is not particularly limited, but a sodium salt of carboxylic acid as a hydrophilic group and / or A surfactant having a potassium salt is preferable, and examples thereof include sodium oleate, potassium oleate, disproportionated sodium rosinate, and disproportionated potassium rosinate.

Examples of the coagulant used when recovering the polymer include mineral acids such as sulfuric acid, phosphoric acid and nitric acid, organic acids such as acetic acid, sulfates of alkaline earth metals such as magnesium sulfate and calcium chloride, or One or more selected from chlorides can be used.
In the present invention, for the above-mentioned coagulant, a water-soluble polymer, for example, polyalkylene oxide such as polyethylene oxide and polypropylene oxide, polyvinyl alcohol, hydroxyethyl cellulose, sodium polyacrylate, polyvinyl pyrrolidone, polyacrylamide, Polydimethylaminoethyl methacrylate or the like may be added.

The additive for synthetic resin constituting the additive dispersion for synthetic resin in the present invention is not particularly limited as long as it is a compound dispersible with a surfactant or the like. For example, a lubricant, a plasticizer, a flame retardant, Examples thereof include one or more compounds selected from antistatic agents, stabilizers, pigments, dyes, inorganic fillers, colorants, ultraviolet absorbers, antioxidants, mold release agents, antibacterial agents, and the like. Of these, a dispersion composed of polytetrafluoroethylene is particularly preferable.
Examples of the dispersant for dispersing the additive include anionic surfactants such as alkali metal salts of carboxylic acids such as rosin acid and higher fatty acids, alkali metal salts of alkyl sulfates, and alkali metal salts of alkyl sulfonic acids. And one or more compounds selected from nonionic surfactants such as polyoxyalkylene alkyl ethers.

In the present invention, the additive is contained from a mixed latex containing 99.9 to 40% by weight of polymer latex (converted to solid content) and 0.1 to 60% by weight of additive dispersion for synthetic resin (converted to solid content). When collecting the polymer, the mixed latex is mixed with an aqueous solution of a coagulant to form a paste, and then polymer particles containing almost no fines are recovered by extruding from the pores into warm water and coagulating. It is possible to efficiently recover a polymer containing an additive that does not cause a problem during powder handling.
If the additive dispersion in the mixed latex is less than 0.1% by weight, the mixing effect of the additive is poor, and if it exceeds 60% by weight, fine powder tends to be generated, which is not preferable.

  Further, in the above embodiment, in particular, polymer latex (converted to solid content) of 50 ° C. or lower is 99.9 to 40% by weight and additive dispersion for synthetic resin (converted to solid content) is 0.1 to 60% by weight. The mixed latex containing and the aqueous solution of the coagulant are continuously introduced into a mixer such as a static mixer or a screw pump to obtain a paste, and then warm water of 50 ° C. or more from the pores (0.5 to 20 mm) It is preferred to recover the polymer containing the additive by a method of extruding into solidification.

  Thereafter, the polymer can be recovered by dehydration and drying using a known method such as a centrifugal dehydrator or a fluid dryer.

〔Example〕
In order to describe the present invention more specifically, examples and comparative examples will be described below. However, the present invention is not limited by these. Parts and% are based on weight.

-Preparation of graft polymer latex-
Graft polymer latex (1): Polybutadiene latex (weight average particle size 0.3 μm, gel content 85%, glass transition temperature −80 ° C.) 60 parts (solid content), 140 parts water , Ethylenediaminetetraacetic acid disodium salt 0.1 part, ferrous sulfate 0.001 part, sodium formaldehyde sulfoxylate 0.4 part, and after heating to 65 ° C., a mixture consisting of 10 parts acrylonitrile, 30 parts styrene and A mixture consisting of 1.0 part of potassium oleate and 0.2 part of cumene hydroperoxide was continuously added over 3 hours and polymerized at 65 ° C. for 2 hours to obtain a graft weight of 41.0% solids. Combined latex (1) was obtained.

-Preparation of hard resin polymer latex-
Rigid resin polymer latex (2): 120 parts of water and 0.3 parts of potassium persulfate are placed in a reactor equipped with a stirrer purged with nitrogen, heated to 70 ° C., then mixed with 25 parts of acrylonitrile and 75 parts of styrene, and 1.5 parts of potassium oleate was continuously added over 4 hours, respectively, and further polymerized at 70 ° C. for 2 hours to obtain a hard resin polymer latex (2) having a solid content of 45.0%.

[Example 1]
Using the static mixer shown in FIG. 1 as a mixer, 80 parts (solid content) of the graft polymer latex (1) heated to 40 ° C., 20 parts of titanium oxide and polyoxyethylene lauryl ether of a nonionic surfactant (Product name: Kao-made Emulgen 109P) Polymer latex / titanium oxide dispersion mixed latex mixed with 0.5 part dispersion, and 0.5 parts of sulfuric acid and magnesium sulfate per 100 parts of the mixed latex (solid content) A sulfuric acid / magnesium sulfate mixed aqueous solution containing a portion was continuously added to the mixer to form a paste, and the paste was continuously extruded into warm water heated to 90 ° C. from the pores provided at the outlet of the mixer. Graft polymer / titanium oxide particles were recovered from the resulting slurry using a centrifugal dehydrator and a fluid dryer.

[Example 2]
Using a static mixer shown in FIG. 1 as a mixer, 60 parts (solid content) of a hard resin polymer latex (2) heated to 45 ° C. is added to a polytetrafluoroethylene dispersion (trade name: manufactured by Mitsui Dupont Fluorochemicals). PTFE 30-J, dispersed with nonionic surfactant) Polymer latex / polytetrafluoroethylene dispersed mixed latex mixed with 40 parts (solid content), and 0.25 sulfuric acid per 100 parts of the mixed latex (solid content) A sulfuric acid / magnesium sulfate mixed aqueous solution containing 5 parts of magnesium sulfate and 5 parts of magnesium sulfate was continuously added to the mixer to form a paste, and the paste was continuously added to warm water heated to 95 ° C from the pores provided at the outlet of the mixer Extruded. The obtained slurry was recovered using a centrifugal dehydrator and a fluid dryer to recover the hard resin polymer / polytetrafluoroethylene particles.

[Comparative Example 1]
To 80 parts (solid content) of graft polymer latex (1) heated to 40 ° C. using a coagulation tank with a stirrer, 20 parts of titanium oxide and polyoxyethylene lauryl ether of nonionic emulsifier (trade name: Kao-made Emulgen 109P) Polymer latex / titanium oxide dispersion mixed latex mixed with 0.5 part dispersion, and sulfuric acid / magnesium sulfate containing 0.5 part sulfuric acid and 1 part magnesium sulfate per 100 parts of the mixed latex (solid content). The mixed aqueous solution was continuously added so as to contact at 90 ° C. in the coagulation tank. After the slurry continuously discharged from the coagulation tank is sintered in a heating tank heated to 95 ° C., the obtained slurry is graft polymer / titanium oxide particles using a centrifugal dehydrator and a fluid dryer. Was recovered.

[Comparative Example 2]
In a solid resin polymer latex (2) heated to 45 ° C. using a coagulation tank equipped with a stirrer, polytetrafluoroethylene dispersion (trade name: PTFE 30-J manufactured by Mitsui DuPont Fluorochemicals, Polymer latex / polytetrafluoroethylene dispersed mixed latex mixed with 40 parts (solid content) dispersed with a nonionic surfactant, and 0.25 parts sulfuric acid and magnesium sulfate per 100 parts of the mixed latex (solid content) Each of the sulfuric acid / magnesium sulfate mixed aqueous solutions containing the parts was heated and continuously added so as to come in contact at 95 ° C. in the coagulation tank. The slurry continuously discharged from the coagulation tank was sintered in a heating tank heated to 95 ° C., and then the obtained slurry was centrifuged using a centrifugal dehydrator and a fluid dryer. Fluoroethylene particles were recovered.

[Comparative Example 3]
Using a static mixer shown in FIG. 1 as a mixer, 30 parts (solid content) of a hard resin polymer latex (2) heated to 45 ° C. is added to a polytetrafluoroethylene dispersion (trade name: manufactured by Mitsui Dupont Fluoro Chemical). PTFE 30-J, dispersed with nonionic surfactant) Polymer latex / polytetrafluoroethylene dispersed mixed latex mixed with 70 parts (solid content), and 0.25 sulfuric acid per 100 parts of the mixed latex (solid content) A sulfuric acid / magnesium sulfate mixed aqueous solution containing 5 parts of magnesium sulfate and 5 parts of magnesium sulfate is continuously added to the mixer to form a paste, and the paste is extruded into warm water heated to 95 ° C. from the pores provided at the outlet of the mixer It was. The obtained slurry was recovered using a centrifugal dehydrator and a fluid dryer to recover the hard resin polymer / polytetrafluoroethylene particles.

Fine powder amount : 40 g of polymer particles are screened for 8 minutes with Sonic Shifter L-200P, a sonic vibration sieving machine manufactured by Seishin Corporation, and the ratio of powder passing through a JIS standard sieve having an aperture of 150 microns is measured. (unit:%)
Additive content in polymer: A plate was prepared from 100 g of polymer particles by a hot press method, and the surface of the plate was analyzed by SEM-EDS (JSM-6360LA type, manufactured by JEOL). The amount of titanium oxide and the amount of polytetrafluoroethylene were respectively quantified. (unit:%)

  As described above, when the recovery method of the present invention is applied, polymer particles containing an additive containing almost no fine powder can be recovered, and there is no problem when handling the powder, and the polymer containing the additive is efficiently used. Can be recovered in an industrial manner and is industrially useful.

It is a figure which shows the polymer collection | recovery apparatus containing an additive.

Explanation of symbols

1: Coagulant aqueous solution charging port 2: Polymer latex / additive mixture liquid charging port 3: Mixer 4: Pore 5: Paste 6: Heating tank 7: Dehydrator 8: Dryer 9: Heavy containing additives Combined powder outlet

Claims (5)

A polymer containing the additive is recovered from a mixed latex containing 99.9 to 40% by weight of polymer latex (converted to solid content) and 0.1 to 60% by weight of additive dispersion for synthetic resin (converted to solid content). In this case, the mixed latex is mixed with an aqueous solution of a coagulant to form a paste, and then extruded from the pores into warm water to be coagulated. A method for recovering a polymer, wherein as the polymer latex, one or more of a rubbery polymer latex, a graft copolymer latex and a hard resin polymer latex is a sodium salt of a carboxylic acid as a hydrophilic group. And / or emulsion polymerization in the presence of a surfactant having a potassium salt .

  The method for recovering a polymer according to claim 1, wherein the additive dispersion for synthetic resin is dispersed by a surfactant.   Additives for synthetic resins selected from lubricants, plasticizers, flame retardants, antistatic agents, stabilizers, pigments, dyes, inorganic fillers, colorants, ultraviolet absorbers, antioxidants, mold release agents, antibacterial agents, etc. The method for recovering a polymer according to claim 1, wherein the polymer is one or more kinds of compounds.   The method for recovering a polymer according to claim 3, wherein the additive for synthetic resin is a compound dispersible by a surfactant. The method for recovering a polymer according to any one of claims 1 to 4, wherein the additive for synthetic resin is polytetrafluoroethylene.

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