JPS6195005A - Production of water-absorbing resin containing hydrophobic group - Google Patents

Abstract

PURPOSE:To produce easily a resin having improved water absorption properties, capable of absorbing oily substances, having improved compatibility with rubber and resins, by copolymerizing a hydrophobic group-containing vinyl monomer with an acrylic alkyl ester and an oil-soluble divinyl compound, and saponifying the copolymer. CONSTITUTION:A hydrophobic group-containing vinyl monomer (e.g., styrene, etc.) and an acrylic alkyl ester (e.g., methyl acrylate, etc.) in a molar ratio of preferably 10:90-60:40, and an oil-soluble divinyl compound (e.g., divinyl benzene, etc.) are copolymerized usually by suspension polymerization in a water dispersion system, and, further saponified with an alkali such as NaOH, etc. preferably at 60-65 deg.C. USE:Useful as a sealing material having water leakage stopping effect, windshield wipers for automobile, supporting materials for raising of marine products prepared by blending the resin with nylon, etc.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention absorbs water tens to hundreds of times its own weight, and further contains hydrophobic groups, so it is miscible with resins such as rubber and plastics. This article relates to a method for manufacturing and developing an excellent water-absorbing resin.

[Prior art] In the past, the main products that absorbed and retained moisture were valve products, but in recent years, starch graft polymers (Japanese Patent Publication No. 53-46199) and cellulose modified products (Japanese Patent Publication No. 53-46199),
-80376), a product obtained by copolymerizing an alkali metal acrylic acid salt with a divinyl compound (JP-A-58-71907)
Super absorbent resins have been developed, and powders of these resins are currently widely used in disposable diapers, napkins, etc.

[Problems to be Solved by the Invention] Despite the progress described above, the use of superabsorbent resins is not limited to diapers and napkins, but also sealing materials that have a water-stopping effect as composite materials when kneaded with rubber materials, Attempts are being made to use fibers in automobile wipers, to use fibers kneaded with nylon as supports for aquaculture, and to improve the physical properties of paints and inks by mixing them with paints and inks. However, when conventionally developed superabsorbent resins are used in these composite materials, they have the disadvantage of poor compatibility with lipophilic substances such as rubber paints, resulting in detachment and separation.

[Means for Solving the Problems] In order to overcome this drawback, the present inventor conducted extensive research aimed at synthesizing a water-absorbing resin containing a hydrophobic group, and as a result, the present inventor has developed a relatively easy manufacturing method. We have arrived at the present invention.

In other words, the gist is that a monomer of vinyl having a hydrophobic group, an alkyl acrylate ester, and an oil-soluble divinyl compound are copolymerized, and then saponified with an alkali, thereby containing a hydrophobic group. A water-absorbing resin is obtained.

Examples of vinyl monobases with hydrophobic groups include styrene, chlorostyrene, vinyl chloride, methyl methacrylate, butyl methacrylate, isobutyl methacrylate, etc., but they are limited in price, ease of polymerization operation, and stability during saponification. Styrene is preferred.

Methyl methacrylate can also be used, taking advantage of its slower saponification rate than acrylic esters.

As the acrylic acid alkyl ester, methyl acrylate is most preferred because of its ease of saponification, but ethyl ester,
Butyl esters can also be used.

As the oil-soluble divinyl compound, any oil-soluble divinyl compound such as divinylbenzene and dimethacrylic acid alkyl ester can be used, but divinylbenzene is most preferred from the viewpoint of stability during saponification or after water absorption.

Vinyl monohanging body with hydrophobic group and acrylic acid mel −
- The molar ratio of the kill ester is not particularly limited to any molar ratio in the range of 10:90 to 90:10, but from the viewpoint of the effect of the hydrophobic group and hydrophilicity, the molar ratio of 10:90 to 60:40 is preferable. .

The amount of divinyl compound to be used varies depending on the desired degree of water absorption, but stone is preferably used in an amount of 0.01 to 0.5% based on the total weight of the vinyl polymer having a hydrophobic group and the acrylic acid alkyl ester.

Copolymerization of the three monomers mentioned above can be carried out by any of the commonly used methods such as solution polymerization, emulsion polymerization, and suspension polymerization.

However, in consideration of transportation to the next saponification step, etc., suspension polymerization is most preferred.

Saponification of polymers is usually done with caustic alkali at a temperature of 60 to 65
Conducted at °C. The solvent at this time is not particularly limited, but a mixed solvent of methanol and water is generally used.

After saponification, a drying process is performed and, if necessary, pulverization is performed to obtain a powdery water-absorbing resin.

[Function] The present invention was researched to improve the compatibility of the water-absorbent resin when kneading it into rubber and the like by incorporating hydrophobic molecules such as styrene into the water-absorbing resin. Acrylic acid is often used in conventional water-absorbing resins, but it has been difficult to copolymerize acrylic acid with hydrophobic monomers. The present invention is a water-absorbing resin that easily contains a hydrophobic group by copolymerizing a hydrophobic monomer represented by styrene, an acrylic acid alkyl ester, and an oil-soluble divinyl compound, and then saponifying it with an alkali. It became possible to manufacture.

[°Examples] Next, the present invention will be described in more detail based on Examples, but the present invention is not limited to the Examples below unless it exceeds the gist thereof.

Example 1 Ion exchange in which 3 g of fully saponified polyvinyl alcohol and 2 g of partially saponified polyvinyl alcohol were dissolved in a 1 g five-necked separable flask equipped with a stirrer, thermometer, reflux condenser, nitrogen suction tube, and dropping funnel. 500g of water was charged, heated to 60°C, and replaced with nitrogen. Next, methyl acrylate 76.89 (80 mol%), styrene 23.2
9 (20 mol%), divinylbenzene 0.05 g, and benzoyl peroxide 19 were placed in a dropping funnel.
It was gradually dropped into the ion-exchanged water being stirred. 60℃
After polymerization for 10 hours, a pearl-like polymer with a particle size of about 0.3 m+ was obtained. Filter this through a furnace cloth, put it in a separately prepared 1" separable flask equipped with a stirrer, thermometer, and reflux condenser, and add a solution of 35.7 g of sodium hydroxide dissolved in a mixed solvent of 1009 g of water and 400 g of methanol. Saponification was carried out at 60° C. for 8 hours while stirring. The mixture was furnace-separated again using a furnace cloth, washed with methanol, and dried to obtain a pearl-like water-absorbing resin.

Example 2 Five rosetteable flasks used in Example 1 were charged with 50C1 of ion-exchanged water in which 3.3% of fully saponified polyvinyl alcohol and 0.19% of partially saponified polyvinyl alcohol were dissolved, and heated to 60°C. The atmosphere was replaced with nitrogen. Next, 88.2 g (90 mol%) of methyl acrylate, 11.8 g of styrene
g (10 mol%), divinylbenzene 0.075ff,
A mixture of 1 g of benzoyl peroxide was gradually dropped into the ion exchange water being stirred from a dropping funnel.

When polymerized at 60° C. for 10 hours, a pearl-like polymer with a particle size of about 0.5 mm was obtained. After this was separated in a furnace using a furnace cloth, sodium hydroxide 419 was dissolved therein. 10 (1 part water and 4 methanol
00g of mixed solvent was added and saponified at 60°C for 8 hours with stirring. Furnace separated with furnace cloth, washed with methanol, dried,
A pearl-like water absorbent resin was obtained.

Example 3 Into the five-necked separable flask used in Example 1, 5009 ion-exchanged water in which 3 g of fully saponified polyvinyl alcohol and 3 g of partially saponified polyvinyl alcohol were dissolved was heated to 60° C. and replaced with nitrogen. Next, methyl acrylate 55.49 (60 mol%), styrene 44.69
(40't-ru%), 0.05 g of divinylbenzene, and 2 g of ben-13zoyl peroxide were gradually dropped into the ion-exchanged water being stirred from a dropping funnel. When polymerized at 60° C. for 16 hours, a pearl-like polymer with a particle size of about 0.5 m was obtained. After separating this in a furnace using a furnace cloth, it was placed in the same saponification equipment as in Example 1, and potassium hydroxide was
A mixed solvent of 100 g of water and 400 g of methanol was added, and saponification was carried out at 60° C. for 10 hours with stirring. After being separated using a furnace cloth, the mixture was washed with methanol and dried to obtain a granular water-absorbing resin.

Example 4 In the five-necked separable flask used in Example 1, 39 g of fully saponified polyvinyl alcohol and 0.5 g of partially saponified polyvinyl alcohol were dissolved in 500 g of ion-exchanged water.
g was charged, heated to 60°C, and purged with nitrogen. Next, methyl acrylate 66.79 (70 mol%), methyl methacrylate 33.39 (30 mol%), divinylbenzene 0
．． 05!9, A mixture of 1 g of benzoyl peroxide was gradually dropped into the ion exchange water being stirred from the dropping hole. After polymerization at 60° C. for 8 hours, a granular polymer with a particle size of about 0.5M was obtained.

After separating the mixture using a furnace cloth, it was placed in the same saponification apparatus as in Example 1, and a mixed solvent of 100 g of water containing 28 g of sodium hydroxide and 400 g of methanol was added while stirring, and the mixture was heated at 60°C for 5 hours. . The mixture was separated using a furnace cloth, washed with methanol, and dried to obtain granular water-absorbing resin.

[Effects] The water absorption capacity and the absorption amount of toluene and Isopar M (isoparaffin manufactured by Exxon Chemical Co., Ltd.) were measured for the products produced in Examples 1 to 4.

(1) Disperse 1 g of the water-absorbent resin produced in Examples 1 to 4 in 1 jl of distilled water, let it absorb for 30 minutes, filter it through a 200-mesh nylon screen, and calculate the water absorption capacity using the following formula from the liquid filter. The calculated results are shown in Table 1. The absorption capacity is expressed as (11-weight of water-absorbing resin).

Table 1 (2) 5g of the water absorbent resin produced in Examples 1 to 4 was
g of toluene and Isopar M (isoparaffin manufactured by Exxon Chemical Co., Ltd.), and the absorbed amount was measured. For comparison, a similar test was also conducted on a commercially available super absorbent resin (crosslinked polyacrylate). The results are shown in Table 2.

Table 2: As can be seen from Tables 1 and 2, the water-absorbing resin containing LIi aqueous groups produced by the method of the present invention has water-absorbing properties, and also absorbs oily substances, and has amphiphilic properties. It is made of water-absorbing resin.

Furthermore, the high water absorption capacity resin of the present invention can be used in the same way as commercially available super absorbent resins, and this phenomenon is less likely to occur when dispersed in water, perhaps because it contains hydrophobic groups.
It also has the characteristic of having a fast water absorption rate. Also, perhaps because an oil-soluble divinyl compound is used, the gel that has absorbed water is less likely to be dissolved by ultraviolet light.

Patent applicant: Kyoritsu Organic Industrial Research Institute Co., Ltd. and one other person Procedural amendment November 1982/Japanese Patent Application No. 215956 2 Name of the invention Method for producing a water-absorbing resin containing a hydrophobic group 3. Relationship with the case of the person making the amendment Applicant name: Kyoritsu Organic Industrial Research Institute 4, Agent address: 1-1-5 Minami-Aoyama-chome, Minato-ku, Tokyo Date of amendment order (voluntary) ( Date of dispatch) Showa, Month, Day 6, Subject of amendment r, Contents of amendment (1) 6th edition of the specification, lines 12-13, ``Examples below'' is corrected to ``Examples below.''

(2) Page 6, line 15 Correct "nitrogen suction pipe" to "nitrogen blowing pipe".

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Claims (6)

[Claims] (1) Water absorbency containing a hydrophobic group characterized by copolymerizing a vinyl monomer with a hydrophobic group, an acrylic acid alkyl ester, and an oil-soluble divinyl compound, and further saponifying it with an alkali. Method of manufacturing resin. (2) The method for producing a water-absorbing resin containing a hydrophobic group according to claim 1, wherein the vinyl monomer having a hydrophobic group is styrene. (3) The method for producing a water-absorbing resin containing a hydrophobic group according to claim 1, wherein the acrylic acid alkyl ester is methyl acrylate. (4) The method for producing a water-absorbing resin containing a hydrophobic group according to claim 1, wherein the oil-soluble divinyl compound is divinylbenzene. (5) Molar ratio of styrene and methyl acrylate is 10:9
A method for producing a water-absorbing resin containing a hydrophobic group according to claim 1, wherein copolymerization is carried out with an oil-soluble divinyl compound in a ratio of 0 to 60:40. (6) A method for producing a water-absorbing resin containing a hydrophobic group according to claim 1, wherein the copolymerization is carried out by suspension polymerization in an aqueous dispersion medium system.