JPH01304104A - Preparation of filler-reinforced water-swelling gel - Google Patents

Abstract

PURPOSE:To obtain a highly water-absorbing gel compsn. exhibiting no pasty state even when it absorbs water by adding a soln. of a specified Si compd. to an inorg. sol dispersed in water or an org. solvent to modify it, adding furthermore a specified polymerizable monomer and a catalyst and polymerizing it. CONSTITUTION:A soln. of at least one compd. of formula I or II (wherein X is a hydrophobic substituent) (e.g., gamma-methacryloxypropyltrimethoxysilane) dissolved in water or an org. solvent is added to an inorg. sol (e.g., silica sol or alumina sol) dispersed in water or an org. solvent to modify it and furthermore, a hydrophilic polymerizable monomer having a C=C double bond (e.g., acrylic acid, its metal salts, acrylamide, its deriv.) and a polymn. catalyst are added thereto and polymerized to prepare the title gel. As this filler-reinforced gel compsn. has high strength and the swelling property is not spoiled, it is useful in such wide applications as a water-absorbing agent for sanitary materials, a drying inhibitor, a humidity adjusting agent, a solidifying agent for dirt mud, or an antistatic agent.

Description

[Detailed description of the invention]

A8 Purpose of the invention I...-1! p The present invention relates to a method for dispensing a highly reinforced and highly water-absorbing gel composition that does not exhibit a paste-like appearance when water is absorbed. Recently, a super absorbent polymer that absorbs several hundred times its own weight in water and retains it has been developed, and is used as a water absorbing agent for sanitary materials such as disposable diapers, sanitary products, and medical underbats, and for drying. It is used for a wide range of purposes, including as an inhibitor, humidity regulator, sludge solidifying agent, and antistatic agent. For example, it has been proposed to use materials with high water absorption and water retention properties during sowing to avoid poor germination due to lack of water in the seeds. However, Japanese Unexamined Patent Publication No. 57-335
As reported in No. 08, etc., it is not the case that any superabsorbent polymer can be used in these applications, but only superabsorbent polymers that do not exhibit a pasty-like appearance when water is absorbed are effective. It has been known. Furthermore, when a superabsorbent polymer is used as a water absorbing agent for sanitary materials, if it is pasty, problems such as contamination due to extrusion may occur. As mentioned above, when trying to utilize superabsorbent polymers, their mechanical properties are very important. Conventionally, methods for improving the mechanical properties of water-swellable gel compositions include increasing the crosslinked network density of the gel composition, or using a monomer that provides a segment with low water absorption as a third component. has been taken. However, there is a limit to improving the mechanical properties using only the above method, and it has been extremely difficult to obtain even higher properties. In view of the above circumstances, in order to improve the mechanical properties of the current superabsorbent polymer without impairing other properties, the present inventors have developed a new method for improving mechanical properties that should be added to the above two methods for improving mechanical properties. method, which is commonly used in rubber compositions.
As a result of intensive studies from the viewpoint of agent reinforcement, we found that a gel composition with a filler network created by filler reinforcement has superior mechanical properties at the same degree of swelling compared to a gel composition with only a crosslinked network. I found out something. However, when attempting to combine the filler used for reinforcement with the gel composition in the form of powder, the powder to be filled settles, making it difficult to prepare a stable gel composition. ,[I am ゛Yorito-゛71. The object of the present invention is to provide a method for producing a filled and reinforced water-swellable gel that exhibits high mechanical properties when swollen with water. 8. Structure of the Invention The method for producing the filler-reinforced water-swellable gel according to the present invention is as follows:
A solution of at least one compound represented by the general formula % (where X is a hydrophobic substituent) dissolved in water or an organic solvent is added to an inorganic sol dispersed in water or an organic solvent. It is characterized in that it is modified and further polymerized by adding a hydrophilic polymerizable heptamer having a C═C double bond and a polymerization catalyst. The inorganic sol that supplies fine powder as a filler in the filler-reinforced water-swellable gel obtained by the present invention is one selected from colloidal silica (silica sol), alumina sol, zirconia sol, antimony oxide sol, etc. The sol is not limited to these as long as it is selected from a mixture of these or is an inorganic sol. In the filler-reinforced water-swellable gel obtained according to the present invention, the amount of filler must be 5 to 50% by weight, preferably 10 to 40% by weight, and more preferably 15 to 35% by weight. If the amount of the dispersed phase is less than 5% by weight, the filler reinforcing effect will be poor, and if it exceeds 50% by weight, the degree of swelling will be extremely low. Therefore, the amount of inorganic sol used in the filled-reinforced water-swellable gel according to the present invention is sufficient to supply one of the above-mentioned fillers. The solid content of the inorganic sol used is 5 to 60% by weight, preferably 10 to 50% by weight. The fine powder used as a filler in the filler-reinforced water-swellable gel of the present invention is a compound containing at least one silicon element in the molecule, which is represented by the general formula % (%). It is necessary to process it in the form of an inorganic sol, which is the supply body. The treatment of the inorganic sol with the above compound is used in the present invention in anticipation of a coupling effect between the reinforcing /S fine powder and the polymerizable monomer. Since the substituent X in the above compound has an affinity with the polymerizable monomer described below, it is necessary to aggregate or react with the polymerizable monomer. As the substituent X having affinity with the polymerizable monomer, in the structure of (I), a vinyl group,
Allyl group, 1-propenyl group, 2-propenyl group, 1-
Butenyl group, 2-butenyl group, 2-pentenyl group, 5-
Bicyclohebutenyl group, 2-(3-cyclohexenyl)
Substituents having a C=C double bond such as ethyl group, acryloyl group, methacryloyl group, cinnamoyl group, styryl group, γ-methacryloxypropyl group, γ-aminopropyl group, N-(βaminoethyl)-γ - Things with amino groups such as aminopropyl group, N-(3-acryloxy-2-hydroxypropyl)3-aminopropyl group, Y-anilinopropyl group, Y-glycidoxypropyl group, etc. For the structure of (II), vinylene group, propenylene group, trimethylene group, tetramethylene group, pentamethylene group, octamethylene group, propylene group, ethylidene group, maleic acid diester structure. A difunctional substituent corresponding to the monofunctional substituent described above, such as a compound having a polyethyleneimine structure, is used. Furthermore, in order to increase the degree of swelling of the filler-reinforced gel composition of the present invention, a processing agent may be used to impart a charged structure to the surface of the fine particles. The processing agent is a compound containing at least one silicon element in the molecule represented by the same general formula as the coupling agent, % ( ), and the substituent X is 2-methacryloxethyl. dimethyl

[3-Trimethoxysilylpropyl] Ammonium chloride, N-β. -(N-vinylbenzylaminoethyl)-γ-aminopropyltrialkoxysilane, octadecyldimethyl (
3-()-rimethoxysilyl)propyl] It has either an ammonium salt structure such as ammonium chloride or an anion structure such as a phosphonium salt structure, or both structures. are preferably used. The above-mentioned two types of compounds containing at least one silicon element in their molecules are sufficiently effective when used alone, but their effects can be further enhanced when used in combination. The total amount of the above-mentioned compound containing at least one silicon element in the molecule is 10% of the solid content in the inorganic sol.
It is necessary that the amount is 3 to 80 parts by weight, preferably 5 to 50 parts by weight, and more preferably 8 to 80 parts by weight.
It is desirable that the amount is 40 parts by weight. If the amount of the compound containing at least one silicon element in the molecule is less than 3 parts by weight, the strength of the filler-reinforced gel composition will not be sufficient;
If the amount exceeds 1 part by weight, a sedimentation phenomenon will occur during the preparation of the filler-reinforced gel composition, making it extremely difficult to prepare the filler-reinforced gel composition. As the hydrophilic polymerizable hexamer having a C═C double bond according to the present invention, either a highly water-absorbing material or a low water-absorbing material can be used. The monomers include those having a cation structure such as an ammonium salt structure or a phosphonium salt structure; an anion represented by carboxylic acid and its metal salt, sulfonic acid and its metal salt, phosphoric acid and its metal salt, etc. and nonionic structures represented by ethylene glycol, polyvinyl alcohol, etc., or those having multiple structures are preferably used, and each can be used alone or in a mixture. . Specific examples of hydrophilic polymerizable monomers having a C═C double bond include those having a cationic structure, and N as a material having a cationic structure as a result. N-dimethylaminoethyl acrylate and its quaternary salt, N,N-dimethylaminoethyl methacrylate and its quaternary salt, N,N-dimethylaminoethyl acrylamide and its quaternary salt, N,N-dimethylaminoethyl methacrylamide and quaternary salt thereof, N,N-dimethylaminopropyl acrylate and quaternary salt thereof, N,N-dimethylaminopropyl methacrylate and quaternary salt thereof, N,
N-dimethylaminopropylacrylamide and 4
N,N-dimethylaminopropylmethacrylamide and its quaternary salt, allylamine and its quaternary salt, acrylamide and its derivatives, methacrylamide and its derivatives, acryloylmorpholine, and the like. Examples of substances that have or can have an anionic structure include carboxylic acid derivatives such as acrylic acid and its metal salts, methacrylic acid and its metal salts, maleic acid and its metal salts, and p-styrene sulfone. Examples include acids and metal salts thereof, sulfonic acids and derivatives thereof such as 2-acrylamido-2-methylpropanesulfonic acid and metal salts thereof. Furthermore, examples of substances that have or can have a nonionic structure include polyethylene glycol acrylate,
Those having an ethylene glycol structure in the molecule such as methoxypolyethylene glycol acrylate, polyethylene glycol methacrylate, methoxypolyethylene glycol methacrylate, allyloxypolyethylene glycol, methoxyallyloxypolyethylene glycol, hydroxyethyl acrylate, hydroxyethyl methacrylate , polyvinyl alcohol acrylate, polyvinyl alcohol methactulate, allyloxy polyvinyl alcohol, diallyloxy polyvinyl alcohol, etc., which have a hydroxyl group structure in the molecule, etc., or hydrophilic polymers having the C═C double bond. However, the invention is not limited to these unless it goes beyond the spirit of the present invention. Furthermore, the filler-reinforced gel composition of the present invention may be made three-dimensional by using a hydrophilic bifunctional polymerizable monomer as a crosslinking agent, and the hydrophilic bifunctional polymerizable monomer includes:
Methylenebisacrylamide 1', methylenebismethacrylamide, methylenebisacrylate, methylenebismethacrylate, polyethylene glycol diacrylate, methoxypolyethylene glycol acrylate, polyethylene glycol dimethacrylate, methoxypolyethylene glycol methacrylate, diallyloxypolyethylene glycol, Examples include polyvinyl alcohol diacrylate, polyvinyl alcohol dimethacrylate, diallyloxypolyvinyl alcohol, etc., but the bifunctional polymerizable monomer is not restricted to these unless it goes beyond the spirit of the present invention. The filler-reinforced gel composition of the present invention comprises the inorganic sol described in 1.
Polymerization is carried out by adding a polymerization catalyst to an aqueous solution of a hydrophilic polymerizable monomer having a =C double bond and a compound containing at least one silicon element in the molecule, which is represented by the general formula % (%). You can get it by doing. The polymerization catalysts used in the above polymerization reaction include potassium peroxide specific sulfate, ammonium peroxide disulfate, butyl hydroperoxide, tert-butyl peroxide, cumene hydroperoxide, acetyl peroxide, benzoyl peroxide, and peroxide. Any commonly used radical initiator such as lauroyl, azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, azobis-2-amidinopropane/HCR salt, etc. can be used, and the polymerization It can be selected depending on the conditions, or mainly water-soluble ones can be preferably used in the present invention. EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof. "Mi" L Sword" 2 40g of colloidal silica (Snowtex C: manufactured by Nissan Kagaku Kaiku) and TSL8370 (Toshiba Silicone Ii [J
:γ-methacryloxypropyltrimethoxysilane) 2
．． 8g and TSL8331 (Toshiba silicone [1:γ
-aminopropyltriethoxysilane) 1.2g in 7.
Aqueous solution α dissolved in 2 g of water was gradually added to prepare a modified colloidal silica aqueous solution. On the other hand, an aqueous solution was prepared by dissolving 12 g of acrylic acid sodium salt, 27 g of acrylamide, and 0.5 g of methylenebisacrylamide in 150 m of water. To this aqueous solution, the above-mentioned modified Corro-tal silica water/8 solution was gradually added and stirred. After thorough stirring, 0.4 mg of ammonium peroxide diasulfate and 200 μp of tetraethylethylenediamine were added and stirred. The resulting mixed solution was heated at about 40° C. for 3 hours to polymerize and obtain a filler-reinforced gel composition. Ta. According to the method of synthesis side 1 of the dispersion phase of the fire, colloidal silica (Snowtex C) 40g, processing agent (Toshiba Silicone TL)
(Manufactured by Toray Silicone / AY43-021: octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride) 2.8 g (Manufactured by Toray Silicone / TSL8370) 1°. Og, 12g of sodium acrylate, 25g of polyethylene glycol acrylate, 0.5g of methylenebisacrylamide, and 0.4mg of ammonium peroxide sulfate salt as a catalyst, 200μβ of tetraethylethylenediamine.
A filler-reinforced gel composition was prepared using the following method. 1. 40 g of commercially available silica (Aerosil 200: manufactured by Nippon Aerosil ■) was mixed with TSL8370 (manufactured by Toshiba Silicone ■) 2
．． On the other hand, an aqueous solution was prepared by dissolving 12 g of acrylic acid sodium salt, 27 g of acrylamide, and 0.5 g of methylenebisacrylamide in 200 m of water, and this aqueous solution The above-mentioned modified silica powder was gradually added and stirred. After sufficiently stirring and dispersing, 0.4 mg of peracid specific ammonium sulfate and 200 μρ of tetraethylethylenediamine were added and stirred, and the resulting mixed solution was heated at about 40°C. Polymerization was performed by heating for 3 hours to obtain a filler-reinforced gel composition. 12 g of sodium acrylic acid salt and 27 g of acrylamide.
After preparing an aqueous solution in which 0.5 g of methylene bisacrylamide and 0.5 g of methylene bisacrylamide were dissolved in 200 m of water and stirring thoroughly, 0.4 mg of peracid specific ammonium sulfate and 200 μC of tetraethylethylenediamine were added and further stirred to obtain a mixed solution. was heated at about 40°C for 3 hours to polymerize and obtain a gel composition. Former Kasadan Niacrylic acid sodium salt 12g, acrylamide 27g
and 1.8 g of methylenebisacrylamide at 200 mI
After preparing an aqueous solution of step 2 and stirring thoroughly,
0.4 mg of peracid specific ammonium sulfate and 2°Oμβ of tetraethylethylenediamine were added and further stirred, and the resulting mixed solution was heated at about 40°C for 3 hours to polymerize and obtain a gel composition. The degree of swelling of each sample was measured by the gravimetric method, and the strength and hardness were measured by the compression method. The evaluated values are shown in Table 1. Table 1 *1: 1 cm' cross-sectional area x approximately 1.0 cm sample
When the amount of strain when a weight of 00g is placed is △l, (Δl/
Relative value when Comparative Example 3 is taken as 100 in the value expressed by l o )/(0,1/lo') *2: Determined by gravimetric method. *3: Weight of the plow when the sample used in *1 was destroyed. *4 Rainbow lily was separated and a good sample could not be obtained. As is clear from Table 1, the filler-reinforced gel composition of the present invention has high strength and no loss of swelling properties, and is free from sedimentation and
It was excellent with no separation. C1 Effects of the Invention The filler-reinforced gel composition of the present invention has high strength and does not impair swelling properties, so it can be used as a water absorbing agent for sanitary materials, an anti-drying agent, a humidity regulator, a solidifying agent for sludge, and an electrostatic charger. It can be usefully used in a wide range of applications, such as as an inhibitor.

Claims (1)

[Claims] An inorganic sol dispersed in water or an organic solvent has a general formula ▲ has a mathematical formula, a chemical formula, a table, etc. ▼ (I) or ▲ has a mathematical formula, a chemical formula, a table, etc. ▼ (II) [However, X is Hydrophobic substituent] A solution of at least one compound represented by [hydrophobic substituent] dissolved in water or an organic solvent is added to modify the compound, and a hydrophilic polymerizable monomer having a C=C double bond and a polymerization catalyst are added. A method for producing a filler-reinforced water-swellable gel, which further comprises polymerizing.