Non-particulate organic porous absorbent and method for producing non-particulate organic porous absorbent

Abstract

To provide a non-particulate organic porous absorbent that allows control of the absorption rate or absorption capacity of water, organic solvents, oils, or other organic liquids.SOLUTION: A non-particulate organic porous absorbent is a polymer of monomers that include a low Tg monomer whose homopolymer exhibits a glass transition temperature below 0°C, the absorbent comprising an emulsifier.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a non-particulate organic porous absorbent material capable of absorbing organic liquids and the like, and a method for producing the non-particulate organic porous absorbent material. [Background technology]

[0002] Organic porous absorbents capable of absorbing water and organic liquids such as organic solvents and oils are known.

[0003] For example, Patent Document 1 describes an absorbent continuous porous material having excellent absorbency for both oil and water, which is obtained by polymerizing a W / O emulsion containing a hydrophilic polyurethane polymer and an ethylenically unsaturated monomer as a continuous phase, followed by drying. However, the manufacturing method described in Patent Document 1 is complicated, requiring many different chemicals in the manufacturing process. Furthermore, the resulting porous material has a problem in that it has low absorption capacity for water and organic solvents.

[0004] Patent Document 2 describes a method for producing an open-cell polymer foam with water absorbency by hydrolyzing a high internal phase emulsion (HIPE) containing a glassy polymer component and a rubbery polymer component. However, the absorbent material described in Patent Document 2, which is a porous copolymer of a rubbery polymer and a glassy polymer, is thought to have low absorbency for organic solvents due to the presence of ionic groups. Furthermore, Patent Document 2 describes the absorption capacity of synthetic urine, but does not describe the absorption capacity of organic solvents or oils.

[0005] Patent Document 3 describes a layered double hydroxide in which a carboxylic acid is introduced as an intermediate layer between basic layers made of a metal double hydroxide as a selective adsorbent for oleic acid. However, the layered double hydroxide of Patent Document 3 has the problem that the adsorption amount of oleic acid is not large. Furthermore, Patent Document 3 does not describe the maximum absorption amount of oleic acid.

[0006] In light of these circumstances, there is a demand for non-particulate organic porous absorbents that are capable of controlling the absorption rate and amount of water and organic liquids such as organic solvents and oils. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-082258 [Patent Document 2] Special Publication No. 2002-505702 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-190854 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a non-particulate organic porous absorbent capable of controlling the absorption rate or amount of water and organic liquids such as organic solvents and oils, and a method for producing the non-particulate organic porous absorbent. [Means for solving the problem]

[0009] The present invention relates to a non-particulate organic porous absorbent material that is a polymer of monomers containing a low Tg monomer that has a glass transition temperature of less than 0° C. when made into a homopolymer, and that contains an emulsifier.

[0010] In the non-particulate organic porous absorber, the polymer is preferably a copolymer of monomers containing the low Tg monomer and a high Tg monomer whose glass transition temperature is 0°C or higher when made into a homopolymer.

[0011] In the non-particulate organic porous absorber, the low Tg monomer is preferably at least one of a linear, branched, or cyclic alkyl ester of acrylic acid having two or more carbon atoms, and a linear, branched, or cyclic alkyl ester of methacrylic acid having six or more carbon atoms.

[0012] In the non-particulate organic porous absorber, the low Tg monomer is preferably at least one of dodecyl (meth)acrylate, stearyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

[0013] In the non-particulate organic porous absorber, the high Tg monomer is preferably at least one of methyl acrylate and a linear, branched, or cyclic alkyl ester of methacrylic acid having 1 to 5 carbon atoms.

[0014] In the non-particulate organic porous absorber, the high Tg monomer is preferably t-butyl (meth)acrylate.

[0015] In the non-particulate organic porous absorbent, the content of the emulsifier is preferably in the range of 2 to 70% by mass relative to the mass of the polymer.

[0016] The present invention is a method for producing a non-particulate organic porous absorber, which includes an emulsification step of preparing an emulsion containing water, a low Tg monomer that has a glass transition temperature of less than 0°C when made into a homopolymer, and an emulsifier; and a polymerization step of heating the obtained emulsion to perform thermal polymerization. [Effects of the Invention]

[0017] The present invention can provide a non-particulate organic porous absorber capable of controlling the absorption rate or amount of water and organic liquids such as organic solvents and oils, and a method for producing the non-particulate organic porous absorber. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a graph showing the results of comparing the absorption capacity of various liquids (high viscosity) of monolithic absorbents when the compounding ratio (molar ratio) of a low Tg monomer (dodecyl methacrylate (DMA)) is changed in an example. [Figure 2]1 is a graph showing the results of comparing the absorption capacity of various liquids (low viscosity) of a monolith absorbent body when the compounding ratio (molar ratio) of a low Tg monomer (dodecyl methacrylate (DMA)) is changed in an example. [Figure 3] 1 is a graph showing the results of comparing the dimensional changes of monolithic absorbents in Examples with various liquids (high viscosity) when the compounding ratio (molar ratio) of a low Tg monomer (dodecyl methacrylate (DMA)) is changed. [Figure 4] 1 is a graph showing the results of comparing the dimensional changes of monolithic absorbents in Examples with various liquids (low viscosity) by changing the compounding ratio (molar ratio) of a low Tg monomer (dodecyl methacrylate (DMA)). [Figure 5] 1 is a graph showing the results of comparing the initial velocity as an index of the liquid absorption rate of a monolithic absorbent body when the compounding ratio (molar ratio) of a low Tg monomer (dodecyl methacrylate (DMA)) is changed in an example. [Figure 6] 1 is a graph showing the correlation between the viscosity (mPa·s) and the liquid absorption capacity (g / g) of various liquids when the compounding ratio (molar ratio) of a low Tg monomer (dodecyl methacrylate (DMA)) is changed in an example. [Figure 7] 1 is a graph showing the correlation between the viscosity (mPa s) and the initial velocity (1-sec liquid absorption capacity (g / g)) of various liquids when the compounding ratio (molar ratio) of a low-Tg monomer (dodecyl methacrylate (DMA)) is changed in an example. [Figure 8] 1 is a graph showing the absorption capacity (g / g) of water, methyl oleate, oleic acid, and camellia oil of a monolith absorbent versus contact time (sec) at 0 mol % DMA in an example. [Figure 9] 1 is a graph showing the liquid absorption capacity (g / g) of a monolith absorbent for water, methyl oleate, oleic acid, and camellia oil versus contact time (sec) at 5 mol % DMA in an example. [Figure 10] 1 is a graph showing the absorption capacity (g / g) of water, methyl oleate, oleic acid, and camellia oil of a monolith absorbent versus contact time (sec) at 10 mol % DMA in an example. [Figure 11]1 is a graph showing the liquid absorption capacity (g / g) of a monolithic absorbent for water, methyl oleate, oleic acid, and camellia oil versus contact time (sec) at 20 mol % DMA in an example. DETAILED DESCRIPTION OF THE INVENTION

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes an embodiment of the present invention. The embodiment is an example of implementing the present invention, and the present invention is not limited to the embodiment.

[0020] <Non-particulate organic porous absorbent> The non-particulate organic porous absorber according to this embodiment is a polymer of a monomer containing a low Tg monomer that, when made into a homopolymer, has a glass transition temperature of less than 0° C., and contains an emulsifier. The "non-particulate organic porous absorber" is also called a "monolithic organic porous absorber," or sometimes simply called a "monolithic absorber."

[0021] The present inventors have discovered that by using a polymer of monomers containing a low Tg monomer that, when made into a homopolymer, has a glass transition temperature of less than 0°C, and by incorporating an emulsifier into the polymer, it is possible to control the absorption rate or amount of organic liquids such as water, organic solvents, and oils. By adjusting the compositional components and composition ratio of the continuous phase of the monolith absorbent, it is possible to control and improve the absorption rate or amount of organic liquids such as water, organic solvents, and oils.

[0022] In the non-particulate organic porous absorber according to this embodiment, the polymer is preferably a copolymer of monomers containing a low Tg monomer that, when homopolymerized, has a glass transition temperature of less than 0°C and a high Tg monomer that, when homopolymerized, has a glass transition temperature of 0°C or higher. By polymerizing these two types of monomers to form a copolymer, it is easier to control the absorption amount or absorption rate of organic liquids such as water, organic solvents, and oils compared to polymers polymerized using a single monomer. By adjusting the blending ratio of the low Tg monomer and the high Tg monomer, it is possible to control and improve the absorption rate or absorption amount of organic liquids such as water, organic solvents, and oils.

[0023] The non-particulate organic porous absorbent according to this embodiment is a flexible monolithic absorbent that has excellent absorption capacity for water, organic solvents, oils, and other organic liquids regardless of polarity, viscosity, etc. By adjusting the components to be blended and the ratio of those components, the absorption performance of this monolithic absorbent for various liquids can be controlled, and the dimensional change rate of the monolithic absorbent can be controlled.

[0024] The non-particulate organic porous absorbent according to this embodiment can also be made into a monolithic absorbent having excellent absorption capacity for fatty acids and fatty acid esters such as fatty acid triglycerides, and flexibility that allows separation from water.

[0025] By adding and polymerizing a low Tg monomer that has a glass transition temperature of less than 0°C when made into a homopolymer and incorporating an emulsifier into the polymer, the absorption amount of fatty acid esters such as fatty acids and fatty acid triglycerides can be increased.Furthermore, by adjusting the blending ratio of the low Tg monomer and the high Tg monomer, the absorption rate of fatty acid esters can be selectively adjusted, and a non-particulate organic porous absorbent can be obtained that can selectively separate fatty acid esters from a mixture containing water, fatty acids, etc., and fatty acid esters.

[0026] The non-particulate organic porous absorbent according to this embodiment can absorb water by adding a low Tg monomer, which when made into a homopolymer has a glass transition temperature of less than 0°C, as a polymerization component, and incorporating an emulsifier into the polymer. Furthermore, by adding a low Tg monomer as a polymerization component, the absorption rate of water and organic liquids such as organic solvents and oils increases.

[0027] There are no particular limitations on the low Tg monomer, as long as it is a monomer that, when made into a homopolymer (a homopolymer having a number-average molecular weight or weight-average molecular weight of 1000 or more), has a glass transition temperature (Tg) of less than 0° C. Examples of the low Tg monomer include linear, branched, or cyclic alkyl esters of acrylic acid having 2 or more carbon atoms, preferably 8 to 18 carbon atoms, and linear, branched, or cyclic alkyl esters of methacrylic acid having 6 or more carbon atoms, preferably 8 to 18 carbon atoms. Examples of low Tg monomers include ethyl acrylate, propyl acrylate, butyl acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, and docosyl (meth)acrylate. At least one of dodecyl (meth)acrylate, stearyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate is preferred because of its low toxicity and ease of handling, as well as the ease of emulsification and expected retention of the emulsifier due to the hydrophobic interaction between the hydrophobic portion of the emulsifier and the ester portion of the (meth)acrylic acid monomer. Note that the term "(meth)acrylic acid" refers to either "acrylic acid" or "methacrylic acid."

[0028] The high Tg monomer is not particularly limited as long as it has a glass transition temperature (Tg) of 0°C or higher when made into a homopolymer (a homopolymer having a number-average molecular weight or weight-average molecular weight of 1000 or higher). Examples of the high Tg monomer include methyl acrylate or linear, branched, or cyclic alkyl esters of methacrylic acid having 1 to 5 carbon atoms, preferably 1 to 4 carbon atoms. Examples of the high Tg monomer include methyl (meth)acrylate, ethyl methacrylate, glycidyl methacrylate, and butyl methacrylate. From the viewpoint of ease of emulsification, at least one of n-butyl (meth)acrylate, iso-butyl (meth)acrylate, and t-butyl (meth)acrylate is preferred, and t-butyl (meth)acrylate is more preferred.

[0029] The glass transition temperatures (Tg) of homopolymers of low Tg monomers are, for example, as follows: poly(2-ethylhexyl methacrylate): glass transition point 263 K (-10°C) (weight average molecular weight 123,000); poly(dodecyl methacrylate): glass transition point 208 K (-65°C) (weight average molecular weight 290,000); and poly(stearyl methacrylate): glass transition point 173 K (-100°C) (weight average molecular weight 170,000).

[0030] The glass transition temperature (Tg) of a homopolymer of a high Tg monomer is, for example, 391 K (118° C.) (weight average molecular weight is 170,000) for poly(t-butyl methacrylate).

[0031] The molar ratio of the low Tg monomer is greater than 0 mol % and less than 100 mol % of the polymer. By adjusting the molar ratio of the low Tg monomer, it is possible to control the absorption rate and amount of water and organic liquids such as organic solvents and oils.

[0032] For example, by setting the molar ratio of the low Tg monomer to the polymer at more than 20 mol % and not more than 100 mol %, the absorption rate and amount of water and organic liquids such as organic solvents and oils can be improved.

[0033] For example, by setting the molar ratio of the low Tg monomer to the polymer to be greater than 0 mol % and not greater than 10 mol % it is possible to selectively absorb fatty acid esters such as methyl oleate, and for example to separate fatty acid esters from a mixture of water, fatty acids, and fatty acid esters.

[0034] The non-particulate organic porous absorber according to this embodiment has a continuous porous structure, for example, consisting of a continuous skeleton phase and a continuous pore phase, the thickness of the continuous skeleton being in the range of 0.1 to 100 μm, the average diameter of the continuous pores being in the range of 1 to 1000 μm, and the total pore volume being in the range of 0.5 to 50 mL / g. The continuous skeleton phase and the continuous pore phase can be observed by SEM imaging.

[0035] The thickness of the continuous skeleton of the non-particulate organic porous absorber in a dry state is, for example, in the range of 0.1 to 100 μm. The thickness of the continuous skeleton of the non-particulate organic porous absorber in a dry state is determined by SEM observation. If the thickness of this continuous skeleton is less than 0.1 μm, the strength of the porous absorber may decrease. If the thickness of this continuous skeleton is more than 100 μm, the liquid absorption rate may decrease.

[0036] The average diameter of the interconnected pores of the non-particulate organic porous absorber in a dry state is, for example, in the range of 1 to 1000 μm. The average diameter of the interconnected pores of the non-particulate organic porous absorber in a dry state is measured by mercury intrusion porosimetry and refers to the maximum value of the pore distribution curve obtained by mercury intrusion porosimetry. If the average diameter of the interconnected pores is less than 1 μm, the liquid absorption rate may decrease. If the average diameter of the interconnected pores exceeds 1000 μm, the strength of the porous absorber may decrease.

[0037] The total pore volume of the non-particulate organic porous absorbent in a dry state is, for example, in the range of 0.5 to 50 mL / g. The total pore volume of the non-particulate organic porous absorbent in a dry state is measured by mercury intrusion porosimetry. If this total pore volume is less than 0.5 mL / g, the liquid absorption amount and absorption speed may decrease. If this total pore volume exceeds 50 mL / g, the strength of the porous absorbent may decrease.

[0038] The emulsifier is not particularly limited as long as it is a compound having a hydrophilic group such as a sorbitan ester and a hydrophobic group such as a long-chain fatty acid, i.e., a surfactant. Examples of the emulsifier include fatty acid esters of sorbitan acid such as sorbitan monooleate, sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate, and sorbitan sesquioleate, with sorbitan monooleate being preferred because of its ease of emulsion formation.

[0039] The non-particulate organic porous absorbent according to this embodiment is capable of absorbing both water and organic liquids such as organic solvents and oils by containing an emulsifier. This is presumably because the emulsifier, which has both hydrophilic and hydrophobic groups, exhibits hydrophobic interactions with the hydrophobic alkyl groups of the alkyl ester of acrylic acid or methacrylic acid in the structural portion composed of the low-Tg monomer acrylic acid or methacrylic acid, forming hydrophilic regions due to the hydrophilic groups of the emulsifier and hydrophobic regions due to the hydrophobic groups of the emulsifier and the hydrophobic groups of the low-Tg monomer within the monolith absorbent, making it possible to absorb both water and organic liquids such as organic solvents and oils. On the other hand, if the monolith absorbent contains a high-Tg monomer but not a low-Tg monomer, it is presumed that hydrophilic regions due to the hydrophilic groups of the emulsifier are less likely to be formed within the monolith absorbent, making it less likely to absorb water.

[0040] The content of the emulsifier in the organic porous absorbent is, for example, in the range of 2 to 70% by mass, preferably 5 to 20% by mass, relative to the mass of the polymer. If the content of the emulsifier is less than 2% by mass relative to the mass of the polymer, the water-in-oil emulsion may become unstable, and if it exceeds 70% by mass, the resulting porous absorbent may become brittle.

[0041] Examples of organic solvents include alcohol solvents such as methanol and ethanol, aliphatic hydrocarbon solvents such as hexane, ketone solvents such as acetone, aromatic solvents such as toluene, and halogenated solvents such as chloroform.

[0042] Examples of oils include fatty acids such as oleic acid, linoleic acid, and ricinoleic acid; fatty acid esters such as methyl oleate, fatty acid triglycerides, and methyl linoleate; vegetable oils such as camellia oil and castor oil; mineral oils such as heavy oil, liquid paraffin, and silicone oil; and oil-based inks such as Magic Ink (registered trademark) (Teranishi Chemical Industry Co., Ltd.).

[0043] <Method of manufacturing a non-particulate organic porous absorbent> The method for producing a non-particulate organic porous absorber according to this embodiment includes an emulsification step of preparing an emulsion such as a high internal phase emulsion (HIPE) containing water, a low Tg monomer that has a glass transition temperature of less than 0°C when made into a homopolymer, an emulsifier, and optionally a high Tg monomer that has a glass transition temperature of 0°C or higher when made into a homopolymer, and optionally a crosslinking agent and a polymerization initiator, and a polymerization step of heating the obtained emulsion to perform thermal polymerization.

[0044] Highly discontinuous phase emulsions (HIPEs) are comprised of droplets containing water (internal phase) and a continuous phase containing monomers (external phase).

[0045] The method for producing a non-particulate organic porous absorber may include, after the polymerization step, a water removal step of removing water, and a drying step of drying the residue from the water removal step to obtain a non-particulate organic porous absorber. Furthermore, the method for producing a non-particulate organic porous absorber may include a cutting step of cutting the dried non-particulate organic porous absorber to a predetermined size.

[0046] Although the method may vary depending on the type of emulsifier used, the emulsification step may involve, for example, adding water such as pure water dropwise to an oil phase containing a low-Tg monomer, an emulsifier, and, if necessary, a high-Tg monomer, a crosslinking agent, and a polymerization initiator, and emulsifying the mixture by stirring at a predetermined emulsification temperature, for a predetermined emulsification stirring time, and at a predetermined emulsification stirring speed.

[0047] Although the method may vary depending on the type of emulsifier used, the type of stirring, etc., the emulsification temperature in the emulsification step may be, for example, in the range of 0 to 40°C, the emulsification time may be, for example, in the range of 1 to 60 minutes, the emulsification stirring speed may be, for example, in the range of 100 to 300 rpm, and the reaction pressure may be, for example, normal pressure or may be increased to a range of 0.1 to 0.3 MPa.

[0048] The heating temperature in the polymerization step may be, for example, in the range of 30 to 80°C, the heating time may be, for example, in the range of 2 to 48 hours, and the reaction pressure may be, for example, normal pressure or may be increased to a range of 0.1 to 0.3 MPa.

[0049] The crosslinking agent is not particularly limited, but examples thereof include divinylbenzene, divinylnaphthalene, divinylphenyl, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolpropane tri(meth)acrylate, and butanediol diacrylate.

[0050] The polymerization initiator is not particularly limited, and examples thereof include azobis(4-methoxy-2,4-dimethylvaleronitrile), azobisisobutyronitrile, azobis(2,4-dimethylvaleronitrile), azobiscyclohexanenitrile, azobiscyclohexanecarbonitrile, azobis(2-methylpropionamidine) dihydrochloride, benzoyl peroxide, potassium persulfate, ammonium persulfate, hydrogen peroxide-ferrous chloride, sodium persulfate-acidic sodium sulfite, and tetramethylthiuram disulfide.

[0051] By such a production method, the non-particulate organic porous absorbent material can be obtained.

[0052] In conventional methods for producing non-particulate organic porous absorbents, the emulsifier is removed by washing with a solvent after the polymerization step, but in this production method, the emulsifier is left behind without being removed. By leaving the emulsifier behind, it is possible to obtain a non-particulate organic porous absorbent that can absorb both water and organic liquids such as organic solvents and oils.

[0053] The present specification includes the following embodiments. [1] A polymer of a monomer containing a low Tg monomer that has a glass transition temperature of less than 0°C when made into a homopolymer, A non-particulate organic porous absorbent comprising an emulsifier.

[0054] [2] The non-particulate organic porous absorbent according to [1], The polymer is a copolymer of monomers containing the low Tg monomer and a high Tg monomer that has a glass transition temperature of 0°C or higher when made into a homopolymer.

[0055] [3] A non-particulate organic porous absorbent according to [1] or [2], A non-particulate organic porous absorbent, wherein the low Tg monomer is at least one of a linear, branched, or cyclic alkyl ester of acrylic acid having two or more carbon atoms, and a linear, branched, or cyclic alkyl ester of methacrylic acid having six or more carbon atoms.

[0056] [4] The non-particulate organic porous absorbent according to [3], A non-particulate organic porous absorbent material, wherein the low Tg monomer is at least one of dodecyl (meth)acrylate, stearyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

[0057] [5] The non-particulate organic porous absorbent according to [2], The non-particulate organic porous absorbent material, wherein the high Tg monomer is at least one of methyl acrylate and a linear, branched, or cyclic alkyl ester of methacrylic acid having 1 to 5 carbon atoms.

[0058] [6] A non-particulate organic porous absorbent according to [5], A non-particulate organic porous absorbent material, wherein the high Tg monomer is t-butyl (meth)acrylate.

[0059] [7] A non-particulate organic porous absorbent according to any one of [1] to [6], A non-particulate organic porous absorbent material, wherein the content of the emulsifier is in the range of 2 to 70% by mass relative to the mass of the polymer.

[0060] [8] A method for producing a non-particulate organic porous absorbent according to any one of [1] to [7], an emulsifying step of preparing an emulsion containing water, a low Tg monomer that has a glass transition temperature of less than 0°C when made into a homopolymer, and an emulsifier; a polymerization step of heating the obtained emulsion to carry out thermal polymerization; A method for producing a non-particulate organic porous absorbent, comprising: [Example]

[0061] EXAMPLES The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0062] Example 1 [Production of non-particulate organic porous absorbents] (Preparation of oil phase) We synthesized non-particulate organic porous absorbers using t-butyl methacrylate as the high-Tg monomer and dodecyl methacrylate as the low-Tg monomer. The total weight of the high-Tg and low-Tg monomers was fixed at 28.2 g, and the molar ratio of the high-Tg and low-Tg monomers was varied. We used 2.0 g of divinylbenzene (DVB) as the crosslinker monomer, 3.02 g of sorbitan monooleate (SMO) as the emulsifier, and 0.6 g of azobis(4-methoxy-2,4-dimethylvaleronitrile) as the polymerization initiator. These materials were mixed to prepare the oil phase.

[0063] (Preparation of emulsion (emulsification process)) A high internal phase emulsion (HIPE) was prepared by slowly adding 567 g of pure water as the aqueous phase to the resulting oil phase. The emulsification temperature was 25°C, the emulsification stirring time was 16 minutes, and the stirring speed was 100-300 rpm. The molar ratio of high-Tg monomer to low-Tg monomer was varied to prepare different compositions of the continuous phase. The viscosity of the HIPE was controlled between 6000 and 12000 mPa·s. The viscosity was measured using a Brookfield B-type viscometer at 6 rpm.

[0064] (Polymerization process) The HIPE thus obtained was heated at 40° C. for 4 hours to carry out thermal polymerization (polymerization step).

[0065] (Water removal process, drying process) The obtained polymer was dehydrated under reduced pressure (water removal step), and then dried at 80°C for 18 hours or more (drying step) to obtain a non-particulate organic porous absorbent (monolith absorbent).

[0066] The internal structure of the obtained monolithic absorbent was observed by SEM and found to have a continuous porous structure consisting of a continuous skeleton phase and a continuous pore phase, with the thickness of the continuous skeleton being 5 μm. Mercury intrusion porosimetry measurements revealed that the average diameter of the continuous pores was 7.64 μm and the total pore volume was 17.9 mL / g. The emulsifier content in the obtained monolithic absorbent was 10% by mass relative to the mass of the polymer.

[0067] [Liquid absorption experiment] (Measurement of absorption capacity and dimensional change) The dried monolith absorbent was cut into a 30 mm x 5 mm x 5 mm sample for liquid absorption experiments, and the initial weight (W0 (g)) and initial length (length of the long side, L0 (mm)) of the sample were measured. After immersing the sample in a sufficient amount of liquid for 12 hours (overnight), the sample was removed from the liquid, and the liquid adhering to the sample surface was removed. The weight (W1 (g)) and length of the long side (L1 (mm)) of the monolith absorbent after liquid absorption were measured.

[0068] In order to measure the weight as accurately as possible, the following procedure was carried out.

[0069] In the case of "high viscosity oily liquids" (water, heavy oil A, methyl oleate, oleic acid, camellia oil, liquid paraffin, castor oil, silicone oil), there was a tendency for the liquid to adhere to the surface of the monolith absorbent immediately after removal from the liquid. Therefore, in order to measure the actual amount of liquid absorption more accurately, the monolith was left to stand on a petri dish at room temperature (25°C) for 20 minutes to remove the excess adsorbed amount, and this was used as the amount of liquid absorption.

[0070] In the case of "low viscosity solvents" (hexane, methanol, acetone, chloroform, toluene, refillable water-based ink manufactured by Sanwa Supply Co., Ltd., water-based pigment manufactured by EURONET Co., Ltd., and Magic Ink (registered trademark) manufactured by Teranishi Chemical Industry Co., Ltd.), due to their high volatility, the values ​​measured as quickly as possible without draining the liquid were used.

[0071] The liquid absorption capacity was calculated based on the following formula. Liquid absorption capacity (g / g)=(W1-W0) / W0

[0072] The swelling behavior due to liquid absorption was evaluated by the ratio of the length of the long side of the monolith absorbent body after liquid absorption to its initial length. Length ratio (mm / mm) = L1 / L0

[0073] (Measurement of liquid absorption rate) The dried monolith absorbent was cut into a 30 mm x 5 mm x 5 mm sample for use in the liquid absorption rate experiment, and the initial weight of the sample, W0 (g), was measured. The sample was placed vertically in a tube (inner diameter φ10 mm) with a nonwoven fabric stretched on one end. After the nonwoven fabric portion was allowed to contact the liquid surface for a predetermined time, the weight of the monolith absorbent after absorption (W1 (g)) was measured. The sample was then repeatedly brought into contact with the liquid surface in the same manner, and the contact time and weight were measured to determine the relationship between the liquid contact time and the absorption capacity.

[0074] [Experimental Results] The results of comparing the absorption capacity of various liquids of monolith absorbents when the compounding ratio (molar ratio) of the low Tg monomer (dodecyl methacrylate (DMA)) was changed are shown in Figure 1, Figure 2, and Table 1. Figure 1 shows the results of comparing the absorption capacity of various high-viscosity liquids of monolith absorbents when the compounding ratio (molar ratio) of the low Tg monomer (dodecyl methacrylate (DMA)) was changed, and Figure 2 shows the results of comparing the absorption capacity of various low-viscosity liquids of monolith absorbents when the compounding ratio (molar ratio) of the low Tg monomer (dodecyl methacrylate (DMA)) was changed.

[0075] The results of comparing the dimensional changes of monolith absorbents exposed to various liquids by changing the compounding ratio (molar ratio) of the low Tg monomer (dodecyl methacrylate (DMA)) are shown in Figures 3, 4, and Table 2. Figure 3 shows the results of comparing the dimensional changes of monolith absorbents exposed to various high-viscosity liquids by changing the compounding ratio (molar ratio) of the low Tg monomer (dodecyl methacrylate (DMA)), and Figure 4 shows the results of comparing the dimensional changes of monolith absorbents exposed to various low-viscosity liquids by changing the compounding ratio (molar ratio) of the low Tg monomer (dodecyl methacrylate (DMA)).

[0076] [Table 1]

[0077] [Table 2]

[0078] It was found that by adjusting the ratio of low Tg monomer to high Tg monomer in the monolithic absorbent, it is possible to control the absorption capacity (absorption amount) of various liquids and the dimensional change of the monolithic absorbent due to various liquids.

[0079] Figure 5 shows the results of comparing the initial velocity as an indicator of the absorption rate of the monolithic absorbent when the compounding ratio (molar ratio) of the low Tg monomer (dodecyl methacrylate (DMA)) was changed. Because the absorption rate curves vary greatly depending on the absorbed liquid, for comparison purposes, the amount of liquid absorbed in 1 second after contact with the liquid (1-sec absorption ratio (g / g)) was compared as the initial velocity.

[0080] It was found that the absorption rate (amount of absorbed liquid) of almost all liquids increased by blending dodecyl methacrylate (DMA), a low Tg monomer, as a polymerization monomer in the monolithic absorbent. However, in the case of silicone oil, almost no increase in the amount of absorbed liquid was observed.

[0081] Figure 6 shows the correlation between the viscosity (mPa·s) and absorbency (g / g) of various liquids when the blending ratio (molar ratio) of low-Tg monomer (dodecyl methacrylate (DMA)) is changed.

[0082] Figure 7 shows the correlation between the viscosity (mPa·s) and initial velocity (1-sec liquid absorption capacity (g / g)) of various liquids when the blending ratio (molar ratio) of low-Tg monomer (dodecyl methacrylate (DMA)) is changed.

[0083] Table 3 shows the viscosity of each liquid to be absorbed.

[0084] [Table 3]

[0085] FIG. 8 shows the liquid absorption capacity (g / g) of the monolith absorbent for water, methyl oleate, oleic acid, and camellia oil versus contact time (sec) at 0 mol % DMA.

[0086] Figure 9 shows the liquid absorption capacity (g / g) of the monolith absorbent for water, methyl oleate, oleic acid, and camellia oil versus contact time (sec) when the molar ratio of DMA was changed to 5%.

[0087] Figure 10 shows the liquid absorption capacity (g / g) of the monolith absorbent for water, methyl oleate, oleic acid, and camellia oil versus contact time (sec) when the molar ratio of DMA was changed to 10%.

[0088] Thus, it was found that at 10 mol% DMA, the absorption of methyl oleate was extremely rapid, and that monolithic absorbents with DMA molar ratios of 0%, 5%, and 10% absorbed almost no substances other than methyl oleate.

[0089] FIG. 11 shows the liquid absorption capacity (g / g) of the monolith absorbent for water, methyl oleate, oleic acid, and camellia oil versus contact time (sec) at 20 mol % DMA.

[0090] On the other hand, when the molar ratio of DMA is set to 20%, it is found that in addition to water, methyl oleate, oleic acid, and camellia oil also begin to be absorbed.

[0091] The results of Figures 8, 9, 10 and 11 show that the monolith absorbent containing 0 to 10 mol % of DMA selectively and specifically absorbs methyl oleate in terms of absorption capacity and absorption rate.

[0092] Thus, according to the examples, a non-particulate organic porous absorber (monolithic absorber) was obtained that can control the absorption rate or amount of water and organic liquids such as organic solvents and oils.

Claims

1. a polymer of monomers containing a low Tg monomer that has a glass transition temperature of less than 0°C when made into a homopolymer; A non-particulate organic porous absorbent comprising an emulsifier.

2. 10. The non-particulate organic porous absorbent of claim 1, The polymer is a copolymer of monomers containing the low Tg monomer and a high Tg monomer that has a glass transition temperature of 0°C or higher when made into a homopolymer.

3. 3. The non-particulate organic porous absorbent according to claim 1 or 2, A non-particulate organic porous absorbent characterized in that the low Tg monomer is at least one of a linear, branched, or cyclic alkyl ester of acrylic acid having two or more carbon atoms, and a linear, branched, or cyclic alkyl ester of methacrylic acid having six or more carbon atoms.

4. 4. The non-particulate organic porous absorbent material of claim 3, A non-particulate organic porous absorbent material, wherein the low Tg monomer is at least one of dodecyl (meth)acrylate, stearyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

5. 3. The non-particulate organic porous absorbent according to claim 2, A non-particulate organic porous absorbent material, wherein the high Tg monomer is at least one of methyl acrylate and a linear, branched, or cyclic alkyl ester of methacrylic acid having 1 to 5 carbon atoms.

6. 6. The non-particulate organic porous absorbent according to claim 5, A non-particulate organic porous absorbent material, wherein the high Tg monomer is t-butyl (meth)acrylate.

7. 3. The non-particulate organic porous absorbent according to claim 1 or 2, A non-particulate organic porous absorbent material, characterized in that the content of the emulsifier is in the range of 2 to 70% by mass relative to the mass of the polymer.

8. A method for producing the non-particulate organic porous absorbent according to claim 1 or 2, comprising: an emulsifying step of preparing an emulsion containing water, a low Tg monomer that has a glass transition temperature of less than 0°C when made into a homopolymer, and an emulsifier; a polymerization step of heating the obtained emulsion to carry out thermal polymerization; A method for producing a non-particulate organic porous absorbent, comprising:

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