JP5202274B2 - Method for producing porous polymer particles - Google Patents

Description

  The present invention relates to a porous polymer particle suspension and a method for producing porous polymer particles.

Porous polymer particles are expected to be used in a wide range of applications, including products aimed at deodorizing various malodors that occur in daily life and deodorizers for industrial deodorizing products. . Regarding a method for producing porous polymer particles, Patent Document 1 discloses a production method using a suspension polymerization method. In such a production method, first, a monomer component, an organic solvent, a surfactant, water and, if necessary, a polymerization initiator are mixed to prepare an oil-in-water emulsion. Next, the emulsion is heated and subjected to a polymerization process, so that polymer particles are phase-separated from the organic solvent in the oil phase. In order to obtain porous polymer particles, it is necessary to remove the organic solvent and the like in the particles after the polymerization reaction, and this can be achieved by drying the polymer particle suspension.
JP 2008-1111090 A

  However, if the polymer particle suspension after polymerization is dried as it is, when the organic solvent or the like comes out of the particles, it is foamed by a dispersion stabilizer such as a surfactant present on the particle surface, and the volume increases remarkably. There was a problem that it could not be dried. In addition, when applying porous polymer particles to products, it is sometimes used in a state of being dispersed again in water, etc. instead of being in a powder state. there were.

  Accordingly, an object of the present invention is to obtain a porous polymer particle suspension that can remove an organic solvent or the like in the particles without drying after obtaining the porous polymer particle suspension by suspension polymerization. The object is to provide a method for producing porous polymer particles.

The present invention provides a method for producing a porous polymer particle suspension comprising the following steps (1) and (2), a method for producing a porous polymer particle suspension further comprising the following step (3), and such production. Provided is a method for producing porous polymer particles, wherein a porous polymer particle suspension is obtained by the method, and then the solvent and water are removed.
Step (1): A monomer component including a crosslinkable vinyl monomer and a vinyl monomer having one vinyl group is used with a solvent having a solubility parameter of 9.0 (cal / cm ³ ) ^1/2 or less (hereinafter referred to as solvent 1). Step (2) of copolymerization by an oil-in-water suspension polymerization method: In the reaction solution obtained in Step (1), the solubility parameter is 9.1 to 11.5 (cal / cm ³ ) ^1/2 Step of adding a solvent (hereinafter referred to as solvent 2) and concentrating until the solid content concentration becomes 30% by weight or more: Step of supplying water vapor to the polymer particle suspension concentrated in step (2)

  According to the production method of the present invention, after obtaining a polymer particle suspension by suspension polymerization, the organic solvent in the particles can be removed without drying, and the porous polymer particle suspension and Porous polymer particles can be obtained.

  The method for producing a porous polymer particle suspension of the present invention includes the step (1) and the step (2).

  The crosslinkable vinyl monomer used in step (1) is a monomer having two or more vinyl groups. For example, divinylbenzene, trivinylbenzene, ethylene glycol di (meth) acrylate and the like can be mentioned, and divinylbenzene is preferable. The larger the proportion of the crosslinkable vinyl monomer in the monomer component, the larger the BET specific surface area. The proportion of the crosslinkable vinyl monomer in all monomer components is preferably 5% by weight or more, more preferably 20% by weight or more, and further preferably 50% by weight or more. The upper limit is preferably 98% by weight or less, and more preferably 90% by weight or less.

  The vinyl monomer having one vinyl group used in the step (1) is not particularly limited, and examples thereof include a vinyl monomer having a heteroaromatic ring, an aromatic vinyl monomer, an unsaturated acid ester, and an unsaturated acid. . When using porous polymer particles as a deodorant, a vinyl monomer having a heteroaromatic ring is preferred.

  The vinyl monomer having a heteroaromatic ring may be any compound as long as it contains a vinyl group and a heteroaromatic ring. The heteroaromatic ring refers to a ring containing a hetero atom such as an oxygen atom, a sulfur atom, or a nitrogen atom in addition to a carbon atom as a constituent element of a ring of a cyclic organic compound. Examples of those containing a nitrogen atom include those having one nitrogen atom such as pyridine, pyrrole and quinoline in the ring, and those having two nitrogen atoms such as imidazole, pyrimidine, pyrazine and pyrazole in the ring. Examples of those containing a sulfur atom include thiophene and thiazole. Examples of those containing oxygen atoms include furan. Among these, those containing a nitrogen atom are preferred, and pyridine, imidazole and pyrimidine are preferred. Specific examples of the vinyl monomer having a heteroaromatic ring include 2-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, 2-vinylpyrimidine and the like, and 2-vinylpyridine and 4-vinylpyridine are preferable.

  Examples of aromatic vinyl monomers include styrene, α-methylstyrene, vinyl toluene, ethyl vinyl benzene, vinyl benzyl chloride, and the like, and unsaturated acid esters include methyl (meth) acrylate and ethyl (meth) acrylate. , (Propyl) (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, glycidyl (meth) acrylate, etc. Examples of the saturated acid include (meth) acrylic acid. Moreover, acrylonitrile, methacrylonitrile, etc. can also be used. Of these, aromatic vinyl monomers are preferred, and styrene is particularly preferred.

  When the porous polymer particles of the present invention are used as a deodorant, a vinyl having a heteroaromatic ring in all monomer components in order to sufficiently adsorb malodor components and to support a sufficient amount of metal salt. The proportion of the monomer is preferably sufficiently high, preferably 1% by weight or more, more preferably 2% by weight or more, and further preferably 4% by weight or more. In the case where the absorption effect is enhanced by increasing the BET specific surface area of the porous polymer particles, the proportion of the vinyl monomer having a heteroaromatic ring in all monomer components is preferably 50% by weight or less, and 30% by weight. % Or less is preferable.

  In the present specification, (meth) acrylate means acrylate or methacrylate, and (meth) acrylic acid means acrylic acid or methacrylic acid.

The solvent 1 used in the step (1) is preferably a solvent having a solubility parameter δ (SP value) of 9.0 or less. The solubility parameter here is calculated by the method of Fedors [RFFedors, Polym. Eng. Sci., 14, 147 (1974)], and the unit is represented by (cal / cm ³ ) ^1/2. .

Specifically, the evaporation energy ΔE and the molar volume V are determined from the atomic group constituting the molecule,
δ = (ΔE / V) ^1/2 (cal / cm ³ ) ^1/2
As above, the solubility parameter of each component is obtained. Specific examples of the solvent having a solubility parameter of 9.0 or less include, for example, toluene (8.9), xylene (8.9), hexane (7.3), heptane (7.4) (parentheses) Among these, the solubility parameter value), heptane, and toluene are preferable. The use ratio of the solvent 1 is preferably 5% by weight or more, more preferably 25% by weight or more based on the total monomer weight used from the viewpoint of not reducing the specific surface area of the particles. Moreover, from a viewpoint of obtaining a favorable polymerization rate, 300 weight% or less is preferable with respect to the total monomer weight to be used, and 150 weight% or less is more preferable.

  The dispersion stabilizer used in the oil-in-water suspension polymerization in step (1) is not particularly limited as long as it can form a stable oil-in-water emulsion when the monomer component is mixed with water. For example, dodecyl Anionic surfactants such as sulfate, dodecylbenzene sulfonate, N-stearyl taurate, sulfate salt of polyoxyethylene nonyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene dodecyl phenyl ether, sorbitan monostearate Nonionic surfactants such as rate, polyoxyethylene sorbitan monostearate, and polyvinyl alcohol can be used, but sodium N-stearyl taurate or polyvinyl alcohol is preferred. The amount of the dispersion stabilizer used is not particularly limited as long as the oil-in-water emulsified state is stable. % Is more preferable.

  The polymerization initiator is one that initiates addition polymerization of monomers by radical decomposition with heat, and oil-soluble peroxodisulfates, peroxides, azobis compounds, and the like are used.

In the oil-in-water suspension polymerization in the step (1), a monomer component, a solvent 1, a dispersion stabilizer, water and, if necessary, a polymerization initiator are mixed to prepare an oil-in-water emulsion. When the emulsion is heated and polymerized, polymer particles are phase-separated from the solvent 1 and formed. The polymerization temperature is not particularly limited as long as the polymerization occurs. However, it is preferable to set the polymerization initiator in a temperature range in which the half-life of the polymerization initiator used is about 5 minutes to 10 hours. Although not within the same temperature range, for example, when 2,2′-azobis (2,4-dimethylvaleronitrile) (trade name: V-65B) is used as a polymerization initiator, 50 to 90 ° C. is preferable, 55 to 80 degreeC is especially preferable.
In step (2) of the present invention, first, solvent 2 is added to the reaction solution obtained in step (1). The solvent 2 added in the step (2) has a solubility parameter (cal / cm ³ ) ^1/2 of 9.1 to 11.5, preferably 9.5 to 11, from the viewpoint of preventing foaming during the concentration step. .5, more preferably 10.0 to 11.5. Specific examples of the solvent 2 include, for example, ethyl acetate (9.1), methyl ethyl ketone (9.3), acetone (9.9), n-octanol (10.3), t-butanol (10.6), Examples include n-hexanol (10.7), n-butanol (11.4), isopropanol (11.5) and the like (the values in parentheses are solubility parameter values).

  Further, from the viewpoint of efficiently removing the solvent 1 used in the step (1) from the polymer particles, the logarithmic value (logPow) of the partition coefficient of the solvent 2 added in the step (2) to the octanol / water system is preferable. Is preferably 0.01 to 3.0, more preferably 0.01 to 2.5, and still more preferably 0.01 to 2.1. The logPow mentioned here is the common logarithm of the ratio of the concentration when the solvent is dissolved in n-octanol and mixed with water and the equilibrium is reached (solvent concentration in n-octanol ÷ solvent concentration in water). The value displayed in. The measuring method is shown in (Japanese Industrial Standard Z7260-107). Specific examples of the solvent having a log Pow of 0.01 to 3.0 include, for example, isopropanol (0.05), methyl ethyl ketone (0.29), n-butanol (0.9), and n-hexanol (2.03). N-octanol (3.0) (numbers in parentheses are logPow values).

  Therefore, the solvent 2 added in the step (2) is preferably n-butanol, isopropanol, or n-hexanol from the viewpoints of foaming prevention characteristics during concentration and removal characteristics of the solvent 1 from the polymer particles. .

  Regarding the amount of the solvent 2 to be added in the step (2), the solvent 2 remaining in the system after being concentrated until the polymer solid concentration becomes 30% by weight or more is 20% by weight or more with respect to the polymer solids. Preferably, it is determined in consideration of the amount of the solvent 2 that decreases azeotropically with the water to be distilled off during the concentration. The specific addition amount of the solvent 2 is preferably 50 to 300% by weight and more preferably 100 to 150% by weight with respect to the monomer.

  Concentration can be carried out by any method known in the art, but by evaporating water, solvent 1 used in step (1) and solvent 2 used in step (2) under reduced pressure. It is preferable to do. In the manufacturing method of this invention, it concentrates until solid content concentration becomes 30 weight% or more.

  In the method for producing a porous polymer particle suspension of the present invention, in order to distill off the solvent 1 and the solvent 2 in the polymer particle suspension, it is further concentrated in step (2) as step (3). It is preferable to include a step of supplying water vapor to the polymer particle suspension.

As for the pressure of water vapor, it may be supplied into the tank under pressure or normal pressure, or reduced pressure steam may be introduced.
The pressure in the tank for supplying the steam is preferably reduced in order to efficiently distill off the solvent. The tank internal pressure is preferably 26 kPa to 80 kPa, more preferably 40 kPa to 70 kPa in terms of absolute pressure, in order to easily maintain a constant solid content in the tank during the supply of steam.

  The total supply amount of steam is preferably 0.5 to 2.0 times, more preferably 0.8 to 1.5 times the polymer weight. The supply rate is preferably 0.005 to 0.3 times the polymer weight as the amount of steam supplied per hour from the viewpoint of shortening the process time for distilling off the solvent and preventing vibration of the apparatus during the supply of steam, and 0.02 to 0.15 times is more preferable.

In the present invention, porous polymer particles can be obtained by obtaining a porous polymer particle suspension by the method as described above and then removing the solvent and water by filtration or the like. The BET specific surface area of the obtained porous polymer particles can be arbitrarily set depending on the ratio of the crosslinkable vinyl monomer used for polymerization and the selection of the solvent 1. The BET specific surface area of the porous polymer particles of the present invention is preferably 10 m ² / g or more, more preferably 50 m ² / g or more, and still more preferably 100 m ² / g or more. The upper limit of the BET specific surface area is not particularly limited, but is preferably 800 m ² / g or less from the viewpoint of maintaining the particle strength.

  The BET specific surface area of the porous polymer particles is determined by a BET one-point method using Flowsorb 2300 (manufactured by Shimadzu Corporation). As the adsorbed gas, a gas containing 30% by volume of nitrogen and 70% by volume of helium is used. As sample pretreatment, the adsorbed gas was circulated at 120 ° C. for 10 minutes, then the cell containing the sample was cooled with liquid nitrogen, heated to room temperature after completion of adsorption, and the amount of desorbed nitrogen Determine the surface area. The specific surface area can be determined by dividing the surface area by the weight of the sample.

  The particle size of the porous polymer particles is not particularly defined, and an appropriate one can be selected according to the intended use. From the viewpoint of liquid dispersibility, the thickness is preferably from 0.1 to 10 μm. For example, when composited with another material such as a filter, it is preferably from 1 to 30 μm in terms of the difficulty of dropping off and the particle adhesion rate when composited.

  Porous polymer particles produced by the method of the present invention can be used for a wide range of applications including deodorizers for products intended for deodorization of various malodors generated in daily life and industrial deodorization products. It can be applied to.

  Examples of products aimed at deodorizing various bad odors that occur in daily life include disposable diapers, incontinence products, sanitary products, vaginal supplies, deodorant sprays (aerosol type, trigger type, pump spray type) , Stationary deodorant (gel, solution, sheet, etc.), sheet cleaner (wet type, dry type), human body deodorant (aerosol type, stick type, roll-on type, pump spray type, etc.), for pets Examples thereof include sprays (aerosol type, trigger type, etc.), pet excrement members (sheet-like, granular, etc.), laundry detergents, softeners, finishing agents, hair sprays, and the like.

  Deodorant products for industrial use include deodorant sprays for improving the environment inside and outside the factory, deodorizers, filters for air conditioners, textiles, wallpaper, carpets, clothing (for shirts, socks, etc.) and water purifiers. Can be mentioned.

  When used for such deodorizing applications, the porous polymer particles preferably further contain metal ions. When a vinyl monomer having a heteroaromatic ring is used as the monomer component in the step (1), metal ions are supported on the pore surface by a coordinate bond with the heteroaromatic ring present on the polymer surface layer of the porous polymer particles. It is possible. In this case, malodorous gases such as ammonia, amines, sulfides, and fatty acids are adsorbed by coordinate bonds with metal ions. That is, the porous polymer particles carrying metal ions are particles having a remarkably high deodorizing ability that has both a physical deodorizing ability due to a large BET specific surface area and a chemical deodorizing ability due to the carried metal ions.

  Examples of metal ions include silver ions, zinc ions, aluminum ions, cobalt ions, zirconium ions, cerium ions, iron ions, copper ions, nickel ions, platinum ions and the like, and silver ions and zinc ions are preferred.

  Porous polymer particles carrying metal ions are required by contacting the polymer particle suspension with a solvent in which a metal salt is dissolved after any of the steps (1) to (3). For example, it can be produced by mixing while heating at 30 to 80 ° C.

  The amount of metal ions supported is preferably 0.01% by weight or more, and more preferably 0.1% by weight or more based on the porous polymer particles. Although there is no upper limit in particular, 10 weight% or less is preferable and 5 weight% or less is more preferable.

  The metal salt used for supporting the metal ions on the porous polymer particles is not particularly limited as long as it dissolves in water or an organic solvent. For example, silver nitrate, aluminum nitrate, cobalt nitrate, zirconium nitrate, nitric acid Cerium, iron nitrate (II), iron nitrate (III), copper nitrate, nickel nitrate, silver acetate, cerium chloride, iron chloride (II), iron chloride (III), zinc chloride, copper chloride, silver perchlorate, peroxy Examples include aluminum chlorate, platinum perchlorate, zinc perchlorate, zirconium perchlorate, silver sulfate, aluminum sulfate, copper sulfate, and zinc sulfate. These may be used alone or in combination of two or more. . Particularly preferred are silver nitrate, silver acetate, and zinc chloride.

  The solvent for dissolving the metal salt is not particularly limited as long as the metal salt to be used is dissolved and the deodorant particles are uniformly dispersed. For example, water, diethyl ether, acetone, methanol, ethanol, 1-propanol, Examples include alcohols such as isopropanol and glycerin, and these may be used alone or in combination of two or more.

In the following examples, “%” is based on weight unless otherwise specified. The unit of the solubility parameter (SP value) is (cal / cm ³ ) ^1/2 .

Example 1
20 kg of heptane (SP value: 7.4, logPow = 4.66), 40 kg of monomer (divinylbenzene / 2-vinylpyridine = 75/25) and 2,2′-azobis (2,4-dimethylvaleronitrile) (V -65B, Wako Pure Chemical Industries, Ltd. (0.74 kg) was dissolved, and 108 kg of an aqueous solution in which 1.05 kg of polyvinyl alcohol (Gosenol EG-30, Nippon Synthetic Chemical Co., Ltd.) was dissolved was added and polymerized. The tank was charged. The mixture was emulsified by stirring at 2000 rpm for 20 minutes using a homomixer, and polymerized by heating at 60 ° C. for 6 hours under 50 rpm stirring conditions. To this was added 50 kg of n-butanol (SP value: 11.4, logPow = 0.9), and heptane, n-butanol and water were evaporated under reduced pressure conditions of 42 kPa in the tank while heating to a jacket temperature of 80 ° C. The initial solid content concentration was concentrated from 19% to 33%. There was no process interruption due to foaming during concentration. Thereafter, steam was blown from the bottom of the tank while controlling the jacket temperature so that the solid content concentration was maintained at 31 to 37%, and heptane and n-butanol were subsequently distilled off under a reduced pressure condition of 42 kPa. Distillation was performed until the same amount of vapor as the solid content of the particles was blown to obtain a porous polymer particle suspension. In the obtained porous polymer particle suspension, heptane was 0.01% with respect to the solid content, and n-butanol was 0.9%. The volume average particle diameter of the porous polymer particles was 19.3 μm, and the BET specific surface area was 169 m ² / g.

  The volume average particle size was measured with a laser diffraction particle size distribution analyzer (LA-300 manufactured by Horiba, Ltd.).

Heptane measurement method:
1.00 g of the uniformly mixed porous polymer particle suspension was taken, 9.00 g of acetone was added accurately, and after stirring well, ultrasonic waves were applied for 10 minutes to extract heptane in the porous particles. This was filtered with a filter having a pore size of 0.45 μm, and this filtrate was used as a test solution. Gas chromatographic measurement of the test solution was performed to determine the peak area derived from heptane. The amount of heptane present in the porous polymer particle suspension was determined from a calibration curve obtained by measuring a predetermined amount of heptane solution in advance by gas chromatography.

Example 2
The polymerization process is performed in the same manner as in Example 1, and 70 kg of isopropanol (SP value: 11.5, logPow = 0.05) is added instead of n-butanol, and the inside of the tank is heated to a jacket temperature of 80 ° C. Heptane, isopropanol and water were evaporated under reduced pressure of 42 kPa, and concentrated from an initial solid content concentration of 17.5% to 33%. There was no process interruption due to foaming during concentration. Thereafter, steam was blown from the bottom of the tank while controlling the jacket temperature so that the solid content concentration was maintained at 31 to 37%, and heptane and isopropanol were subsequently distilled off under a reduced pressure condition of 42 kPa. Distillation was performed until the same amount of vapor as the solid content of the particles was blown to obtain a porous polymer particle suspension. Heptane in the obtained porous polymer particle suspension was 0.03% with respect to the solid content, and isopropanol was 0.5%. The volume average particle diameter of the porous polymer particles was 18.0 μm, and the BET specific surface area was 162 m ² / g.

Comparative Example 1
The polymerization process is performed in the same manner as in Example 1, and the initial solids concentration is 24.6% by evaporating heptane and water under reduced pressure conditions of 42 kPa in the tank while heating to a jacket temperature of 80 ° C. without adding n-butanol. Concentration was attempted from 33% to 33%. However, the foaming in the tank was intense and the foam reached the top of the tank, so it was not possible to concentrate.

Comparative Example 2
The polymerization process is carried out in the same manner as in Example 1, but without adding n-butanol, 0.17 kg of antifoam SN deformer 485 (manufactured by San Nopco) is added, and the inside of the tank is heated to a jacket temperature of 80 ° C. Heptane and water were evaporated under reduced pressure of 42 kPa to attempt concentration from an initial solid content concentration of 24.6% to 33%. However, when the solid concentration reached 32%, foaming in the tank occurred, and the foam reached the top of the tank. When 0.17 kg of antifoaming agent was added again, the foam settled, so steam was blown from the bottom of the tank while controlling the jacket temperature so that the solid content concentration was maintained at 31 to 37%, and the same amount as the particle solid content The heptane was subsequently distilled off under a reduced pressure condition of 42 kPa until bubbling of steam was performed. The amount of heptane in the obtained porous polymer particle suspension was 4% based on the solid content.

  The results of Examples and Comparative Examples are shown in Table 1.

Claims (5)

A method for producing a porous polymer particle suspension, comprising the following step (1) , step (2) and step (3) .
Step (1): A monomer component containing a crosslinkable vinyl monomer and a vinyl monomer having one vinyl group is suspended in an oil-in-water solution using a solvent having a solubility parameter of 9.0 (cal / cm ³ ) ^1/2 or less. Step (2) of copolymerization by polymerization method: A solvent having a solubility parameter of 9.1 to 11.5 (cal / cm ³ ) ^1/2 is added to the reaction solution obtained in step (1). Step of concentrating until the solid content is 30% by weight or more
Step (3): A step of supplying water vapor to the polymer particle suspension concentrated in the step (2).   The manufacturing method of the porous polymer particle suspension of Claim 1 whose logarithm value (logPow) of the partition coefficient to the octanol / water system of the solvent added in a process (2) is 0.01-3.0. The manufacturing method of the porous polymer particle suspension of Claim 1 or 2 whose solvent added in a process (2) is n-butanol. The method for producing a porous polymer particle suspension according to any one of claims 1 to 3 , wherein polyvinyl alcohol is used as a dispersion stabilizer in the step (1). The manufacturing method of the porous polymer particle which removes a solvent and water after obtaining the porous polymer particle suspension by the method in any one of Claims 1-4 .