JPH10249195A - Water absorbing resin and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide water absorbing resin superior in light and heat stabilities after aging and suited to outdoor use, and the production method. SOLUTION: The water absorbing resin comprising primary a high polymer material introduced an ion group and containing a stabilizer is disclosed. The water absorbing resin is produced by adding the stabilizer to the high polymer material preliminarily introduced the ion group. Alternatively, the high polymer incorporating the stabilizer is produced by hydrolysis and further introduction of the ion group. By incorporating the stabilizer such as an antioxidant and a light stabilizer, the heat stability or light stability is improved and the weatherability of the water absorbing resin is greatly improved. Also by utilizing used resin waste material (generally these used resin water material incorporates the stabilizer) as raw material, effective use of resources is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-absorbing resin containing a stabilizer and a method for producing the same.

[0002]

2. Description of the Related Art Water-absorbent resins are used in the fields of sanitary materials, agricultural and horticultural fields, food distribution, civil engineering and construction, cosmetics and toiletries, medical care, electric and electronics, paint adhesives, etc.
It is used in various fields and has become a necessity of life.

[0003] Also, studies on application to the preservation of the global environment, such as utilization in desert greening, are being actively conducted.

As described above, the performance required is becoming stricter as the use thereof is expanded and increased, and it is no longer satisfactory simply by having a high water absorption effect as in the prior art. For example, in the field of sanitary goods, improvement in so-called dry touch and reduction in leakage rate are required, and a water-absorbent resin having a higher gelation rate than the water absorption capacity is required.

For this reason, the development of a water-absorbing resin having a high degree of crosslinking has been actively promoted.

[0006]

Under these circumstances, the agricultural and horticultural fields expected to be used as water-absorbent resins have been developed.
In consideration of outdoor use in the field of civil engineering and construction, a water-absorbent resin capable of coping with severe changes in conditions such as light and temperature is required.

[0007] In recent years, the need for a water-absorbing resin that can be used for greening deserts and the like has been increasing due to increasing interest in global environmental conservation, and it has been necessary to supply such a water-absorbing resin inexpensively and in large quantities.

The present invention has been proposed in view of such circumstances, and has as its object to provide a water-absorbent resin having excellent stability over time in outdoor use, and a method for producing the same.

[0009]

Means for Solving the Problems The inventor of the present invention has conducted intensive studies on overcoming the above-mentioned problems, and as a result, by adding a stabilizer to the water-absorbing resin, the change over time due to light, heat, and the like has been reduced. They have obtained the finding that they can be greatly reduced.

The present invention has been completed based on such findings. That is, the water-absorbent resin of the present invention is characterized by being mainly composed of a polymer material into which an ionic group has been introduced, and containing a stabilizer.

Further, the production method of the present invention is characterized in that a stabilizer is added to a polymer material into which an ionic group has been introduced in advance, or a polymer material containing a stabilizer is subjected to a hydrolysis treatment. And introducing an ionic group.

By including a stabilizer such as an antioxidant or a light stabilizer, the composition becomes excellent in heat stability and light stability, and the weather resistance of the water-absorbing resin is greatly improved.

Further, in particular, used resin waste materials (generally,
These used resin waste materials contain a stabilizer. By using) as a raw material, resources can be effectively used, which is also preferable in terms of global environmental conservation.

[0014]

Embodiments of the present invention will be described below in detail.

The water-absorbent resin of the present invention is mainly composed of a polymer material into which an ionic group has been introduced, and contains a stabilizer.

Here, examples of the polymer material into which the ionic group which is the main component of the water-absorbent resin of the present invention has been introduced include the following.

(1) Acrylic acid or a salt thereof, or a crosslinked polymer of both. For example, it can be obtained by the following method. Sodium acrylate + crosslinking agent (crosslinking monomer) → polymerization → drying

(2) A polymer obtained by graft polymerization of acrylic acid, a salt thereof, and acrylonitrile on starch or polyvinyl alcohol. For example, it can be obtained by the following method. a. Starch + acrylic acid + crosslinking agent → graft polymerization → neutralization → drying b. Starch + acrylonitrile → graft polymerization → hydrolysis → neutralization → drying

(3) Hydrolyzate of acrylic fiber. For example, it can be obtained by the following method. Acrylonitrile + acrylic acid + N-methylolacrylamide → polymerization → spinning → hydrolysis → drying

(4) Crosslinked polymer of polyvinyl alcohol. For example, it can be obtained by the following method. Polyvinyl alcohol → cross-linking (orthophosphoric acid, radiation, etc.) → drying

(5) A hydrolyzate (acid-treated product) of a polymer containing acrylonitrile and, if necessary, styrene and conjugated diene.

The polymer material (5) contains an acrylonitrile unit as a constituent unit, and therefore does not exhibit water solubility even when an ionic group is introduced. In a polymer material containing an acrylonitrile unit, the modified product exhibits water absorbability due to hydrolysis of the nitrile portion of acrylonitrile upon introduction of an ionic group.

Here, the content of the acrylonitrile unit in the polymer material of (5) is 2 to 95 mol%, preferably 10 to 60 mol%, more preferably 20 mol%.
５０50%.

If the content of acrylonitrile is too small, the water absorbing effect is reduced, and the water-absorbing resin obtained after the introduction of the ionic group becomes water-soluble, making it impossible to use it as a water-absorbing resin. Would.

On the other hand, if the content of acrylonitrile is too large, the polymer material itself becomes hard, so that it becomes difficult to pulverize and the reforming reaction becomes difficult. In addition, when the content of acrylonitrile is too large, the content of styrene or conjugated diene, which is another constituent unit, becomes small, so that it becomes difficult to swell against an acid such as a solvent or a sulfonating agent, and introduction of an ionic group. Becomes difficult. For this reason, the water absorbing effect on the aqueous electrolyte solution, which is a practical requirement for the water absorbing resin, is reduced.

The constituent units of the polymer material other than acrylonitrile include styrene and conjugated dienes (butadiene, isoprene, etc.). An ionic group (acidic group or alkaline group) is introduced into these constituent units by an ionic group introduction operation (performing an acid treatment or an alkali treatment) to improve water absorption.

The content of the constituent units other than acrylonitrile is at least one of styrene and conjugated diene in the range of 5 to 95 mol%, preferably 20 to 95 wt%, more preferably 40 to 85 mol%, more preferably Is 50 to 80 mol%.

Further, if the polymer material contains styrene and conjugated diene in addition to acrylonitrile,
Further, another constituent unit may be included. These other structural units include maleic anhydride, itaconic anhydride, α-methylstyrene, (meth) acrylamide, (meth) acrylic acid, and (meth) acrylic acid ester (saturated and unsaturated having 1 to 10 carbon atoms). hydrocarbon ),
Examples include vinyl acetate, vinyl chloride, ethylene, propylene, butylene, vinyl pyrrolidone, vinyl pyridine and the like.

The weight average molecular weight (Mw) of the polymer material containing acrylonitrile is 1000 to 20.
000000, further 10,000-1,000,000
Is common. If the molecular weight is less than 1,000, the resulting resin will be water-soluble when subjected to the modification treatment, and a desired water-absorbing resin cannot be obtained. On the other hand, the molecular weight is 20,000
If it is larger than 000, the reforming treatment becomes difficult. However, when the polymer material is a waste material, the molecular weight is not particularly limited because a cross-link may be formed between the resins.

Specific examples of the acrylonitrile-containing polymer material used in the present invention include ABS resin (acrylonitrile-butadiene-styrene resin), SAN resin (styrene-acrylonitrile resin), and ASA resin (acrylonitrile-styrene-acrylate resin). ),
ACS resin (acrylonitrile-chlorinated polyethylene-
Styrene resin), AAS resin (acrylonitrile-acryl-styrene resin), NBR (acrylonitrile-butadiene rubber) and the like.

The above-mentioned polymer material may be mixed with another resin as long as the resin does not inhibit the modification treatment of the present invention. Examples of the different resin include polyphenylene ether, polycarbonate, polyphenylene sulfide, polyethylene terephthalate, polybutylene terephthalate, nylon, polyamide, and polyester. These resins are desirably mixed at a ratio of 60% by weight or less based on the entire polymer material. This is because the content of these different resins is 60% by weight.
This is because, if it exceeds, the introduction reaction of the ionic group may be inhibited.

The above-mentioned polymer material may be a newly produced virgin material, a resin raw material or a discharged product (semi-finished product) in the production process of a molded product, or a cover or case for various uses. Waste materials that are used resins molded for a specific use, such as housings and various component materials used for electric appliances and automobiles, tubes and hoses, and various cushioning materials may be used. Alternatively, it may be a mixture of waste material that is used resin and virgin material. The discharge place may be any of a factory, a store, a process, etc.
Waste collected from factories and dealers is more preferable than general waste from households because many of them have relatively uniform compositions.

Waste materials made of a polymer material are generally roughly classified and treated by three types of methods: landfill, incineration, and remelting. In Japan, landfill and incineration account for about 90% of the total, and at present it is hardly recycled.

As for recycling of waste materials, generally, heating and melting and re-molding (however, only a thermoplastic resin) are performed. However, deterioration of quality due to heat (lower molecular weight, oxidation of resin, etc.), mixing of foreign matter such as dust, or mixing of resins containing various colorants, inorganic pigments serving as reinforcing agents, and metal powder pigments. There were many problems, such as the need for color matching. As described above, when the waste material is recycled by heating and melting, the processing technology and the processing cost have been serious obstacles.

Therefore, if this can be effectively used, it will lead to effective use of resources and contribute to environmental conservation of the earth.

Further, the polymer material may contain additives such as a face dye, a flame retardant, a plasticizer, a filler, and other auxiliary agents.

In particular, in the case of a polymer material containing an inorganic pigment and / or a metal powder pigment, the pigment tends to separate from the surface of the material during the reforming reaction, and a porous surface is generated to increase the reaction surface area. As a result, the reforming reaction is promoted. Subsequently, the porous surface is in a softened state as the reforming reaction is activated. For this reason, even the pigment present in the deeper part is desorbed from the same material, and the reforming reaction is further accelerated.

For the above reasons, the modification reaction of the pigment-containing polymer material is promoted, and the surface of the polymer material after the modification is porous up to the deep portion. Therefore, the water-absorbing resin obtained from this polymer material has a large water-absorbing area, and thus dramatically improves in terms of water absorption capacity and absorption speed.

The content of the above-mentioned inorganic pigment and / or metal powder pigment is 0.01 to 20% by weight, preferably 0.05 to 20% by weight.
-10% by weight.

When the content of the pigment is too small, the effect of accelerating the modification reaction of the polymer material becomes low. On the other hand, if the content of the pigment is too large, it becomes economically disadvantageous,
It becomes difficult to control the reforming reaction.

These inorganic pigments and metal powder pigments include:
Those having good dispersibility with respect to the above-mentioned polymer materials are preferable, and carbon black, iron black, titanium oxide, zinc white, red iron blue, ultramarine blue, cobalt blue, lithopone, zinc sulfide, antimony oxide, yellow iron oxide , Amber, sienna, ocher, viridian, aluminum powder, brass powder, bronze powder and the like. Particularly, carbon black and titanium oxide are preferable.

The carbon black may be produced by any of the channel method, the furnace method and the thermel method, and may be used alone or in combination of two or more. In addition, as an average particle diameter, 5-500μ
m, preferably 10 to 50 μm.

Titanium oxide is a rutile type, an anatase type,
Any type of long particulate titanium may be used, and each may be used alone or in combination of two or more. The average particle size is 0.01 to 50 μm, preferably 0.1 to 50 μm.
05 to 10 μm.

These inorganic pigments and metal powder pigments may be contained alone in the polymer material, or may be contained as a mixture of two or more kinds.

These inorganic pigments and metal powder pigments may be added to the above-mentioned polymer materials for the purpose of producing a water-absorbing resin, or may be a coloring agent, a concealing agent, a reinforcing agent,
The electric conductivity imparting agent may be added for another purpose, or may be used for both purposes. Usually, the above-mentioned used resin waste material contains a face dye such as an inorganic pigment or a metal powder pigment, and further contains a stabilizer described later, so that it is not necessary to newly add these, and It is also advantageous in point.

The ionic group introduced into the hydrolyzate of the above (5) includes a sulfonic acid group, a sulfonate, a chloromethylated amine group, a carboxyl group (carboxylic acid group), a carboxylate, and -PO (OH ) ₂ , —PO (OH) ₂ salt, −
_{CH 2 PO (OH) 2,} -CH 2 PO (OH) 2 salt, -NO
₂ is mentioned. Of these, a sulfonic acid group, a sulfonate, a chloromethylated amine group, and a carboxylate are preferred. These ionic groups may be used alone or two or more of them may be introduced.

The introduced amount of the ionic group is 5 to 95 mol%, preferably 10 to 70 mol%, based on all units.

If the amount of the introduced ionic groups is too large, the modified polymer material exhibits water solubility and cannot be used as a water-absorbing resin. On the other hand, when the introduction amount of the ionic group is small, the water absorbing effect is reduced, and particularly, the water absorbing effect for the aqueous electrolyte solution is reduced.

The introduction of these ionic groups is carried out by subjecting the above-mentioned polymer material to hydrolysis treatment (acid treatment).

The acid used for the acid treatment is preferably an inorganic acid. Examples of the inorganic acid include a sulfonating agent such as concentrated sulfuric acid, sulfuric anhydride, fuming sulfuric acid, and chlorosulfonic acid, and nitric acid, fuming nitric acid, phosphoric acid, phosphorus chloride, and phosphorus oxide. Among these, concentrated sulfuric acid, sulfuric anhydride, fuming sulfuric acid, and chlorosulfonic acid are preferred, and concentrated sulfuric acid having a concentration of 70% by weight or more is particularly preferred.

By reacting the above-described inorganic acid with the polymer material, the acrylonitrile portion undergoes hydrolysis,
An amide group or a carboxyl group is introduced. On the other hand, styrene and -PO (OH)
_2, so that -CH ₂ PO (OH) _2, an ion group and a nitro group is introduced.

When a sulfonating agent is used in the above-mentioned acid treatment, a Lewis base may be used in combination. Examples of the Lewis base include alkyl phosphate (triethyl phosphate, trimethyl phosphate), dioxane, acetic anhydride, ethyl acetate, ethyl palmitate, diethyl ether, thioxane, and the like. In this acid treatment, the amount of the Lewis base used in combination is
1 to 20 with respect to the whole monomer unit in the polymer material
0 mol%, preferably 2 to 100 mol%. In this acid treatment, if the amount of the Lewis base added is less than the above-mentioned range, a gel is easily generated during the reaction, which is not preferable. On the other hand, when the amount of the Lewis base added is larger than the above range, the sulfonation reaction hardly proceeds, which is not preferable.

The amount of the above-mentioned acid to be charged is greatly affected by the concentration of the acid, but is generally 1 to 500 times, preferably 5 to 200 times the weight of the polymer material.

If the amount of the acid is too small, the rate of introduction of ionic groups into styrene or conjugated diene and the rate of hydrolysis of acrylonitrile decrease, and the performance (water absorption) as a water-absorbing resin decreases. I will. On the other hand, if the charged amount of the acid is too large, it is necessary to wash and neutralize the excess acid, which is disadvantageous both economically and operationally.

These acids may be used alone or 2
More than one kind may be used in combination. When used in combination, they may be mixed or added sequentially. For example, after treatment with concentrated sulfuric acid, treatment with sulfuric anhydride may be performed.

Here, specifically, the acid treatment is performed as follows.

(A) First, it is preferable to add either concentrated sulfuric acid or chlorosulfonic acid to the polymer material, and then to add either sulfuric anhydride or fuming sulfuric acid. In this method, first, one of concentrated sulfuric acid and chlorosulfonic acid is added to introduce a sulfone group into styrene or a conjugated diene portion in a polymer material. Then, by adding either sulfuric anhydride or fuming sulfuric acid, the polymer material is subjected to sulfone crosslinking. Therefore, according to this method, a water-absorbing resin having a high degree of crosslinking can be obtained. Therefore, according to this method, a functional resin having excellent shape stability in an aqueous system can be obtained.

(B) First, a sulfonating agent (sulfuric anhydride, fuming sulfuric acid, chlorosulfonic acid, concentrated sulfuric acid, etc.) is reacted with a polymer material in a solvent to introduce a sulfone group into the polymer material. be able to. Or n in the solvent
By adding -butyllithium and further reacting with dry ice, a carboxyl group can be introduced into the polymer material. Alternatively, phosphorus trichloride is added to a solvent and the resultant is further hydrolyzed to introduce a —PO (OH) ₂ group into the polymer material.

(C) Polystyrene resin waste material is chloromethylated with chloromethyl ether and Lewis acid, and further reacted with ammonia or various amine compounds to form tertiary or quaternary amine salts on the resin. Can be introduced as The polystyrene resin is reacted with chloromethylated product and phosphorus trichloride, and further hydrolyzed, so that the polystyrene resin becomes -PO
(OH) ₂ groups can be introduced.

(D) -NO ₂ groups can be introduced into the polymer by reacting with a mixture of sulfuric acid and nitric acid.

The above reforming treatment may be performed in an acid aqueous solution, or may be performed in a system using an organic solvent.

As the solvent used in the reaction system, an aliphatic halogenated hydrocarbon having 1 to 2 carbon atoms (preferably 1, 2 or 3) is used.
-Dichloroethane, chloroform, dichloromethane,
1,1-dichloroethane), aliphatic cyclic hydrocarbon (preferably, cyclohexane, methylcyclohexane, cyclopentane), nitromethane, nitrobenzene, sulfur dioxide, paraffin hydrocarbon having 1 to 7 carbon atoms, acetonitrile, carbon disulfide, tetrahydrofuran , Tetrahydropyran, 1,2-dimethoxyethane, acetone, methyl ethyl ketone, thiophene and the like. Preferred are aliphatic halogenated hydrocarbons having 1 to 2 carbon atoms, aliphatic cyclic hydrocarbons, nitromethane, nitrobenzene, and sulfur dioxide. These solvents may be used alone or as a mixture of two or more. The mixing ratio in the above-mentioned solvent is not particularly limited.

The amount of the organic solvent to be added is preferably less than about 200 times the weight of the polymer material. When the amount of the organic solvent added is larger than this range, the reaction rate of the reforming treatment becomes low and it is economically disadvantageous.

The acid and the organic solvent once used in the above-mentioned reforming treatment may be recovered and used as it is after the reaction, or may be recovered by a technique such as extraction or distillation and used again in the reaction.

In the acid treatment as described above, it is preferable to reduce the particle size of the polymer material as a raw material.
By increasing the surface area of the polymer material, the portion to be modified is increased, and the introduction rate of ionic groups into the polymer material can be improved.

In order to reduce the particle size of the polymer material as described above, a method of pulverizing a lump of the polymer material with a pulverizer or the like and sorting the pulverized material can be used.
When the polymer material contains a rubber component, it is preferable to perform a pulverization process after freezing the waste material at a low temperature.

Further, in order to reduce the particle size of a polymer material such as a polystyrene resin, a method of heating and melting the polymer material and making the polymer material heated and melted into fine particles is used. It can also be used.

Specifically, in the present invention, in order to improve the ionic group introduction rate, it is preferable that the small piece of the polymer material passes through a mesh size of 3.5 mesh or more. If the particle size of the polymer material is larger than this, the surface area of the reactant becomes small and it is difficult to perform the modification treatment, so it takes a long reaction time and is practical, and the performance (water absorption) as a water-absorbing resin is greatly increased Will decrease.

In the above-described reaction for introducing an ionic group into a polymer material, a dispersant may be added to the reaction system when introducing the ionic group. As a result, the polymer material is well dispersed in the reaction system, and the introduction rate of the ionic group is improved.

Further, the reaction temperature of the above-mentioned reforming treatment is as follows:
It varies greatly depending on the type of acid used and whether or not an organic solvent is used, but it is 0 to 200 ° C., preferably 30 to 150 ° C.
° C. If the temperature is too low, the reaction rate becomes too slow to be practical, and the introduction rate of ionic groups is reduced, so that a good water absorbing effect cannot be obtained. On the other hand, when the temperature is too high, the molecular chain of the polymer material is easily broken by thermal decomposition, and the resin shows water solubility, and cannot be used as a water-absorbing resin.

The reaction time varies greatly depending on the reaction temperature, but is generally about 1 minute to 80 hours.
5 minutes to 20 hours. If the reaction time is too short, the reaction does not proceed sufficiently. On the other hand, if the reaction time is too long, the production efficiency will deteriorate.

As described above, the reaction product in which the ionic group has been introduced by the acid treatment may be washed with a large amount of water or neutralized with a reverse aqueous solution.

As a method for washing the polymer after the reaction, the reaction solution is directly added to a large amount of water or a basic aqueous solution, or the reaction product is first filtered from a reaction system with a filter or the like, and this is added to a large amount of water or a base. And a method of pouring into a neutral aqueous solution. At this time, the nitrile group in the polymer material is converted to an amide group or a carboxyl group (or a salt thereof).
Is converted to

Examples of the basic substance used in the basic aqueous solution include oxides, hydroxides, carbonates, acetates of alkali metals (sodium, lithium, potassium, etc.) and alkaline earth metals (magnesium, calcium, etc.). Sulfates, phosphates, etc., ammonia and various (primary to tertiary) amine compounds, etc., are added to the reaction system as they are or gradually in the form of an aqueous solution to complete the neutralization treatment. .

However, in order to improve the water-absorbing effect of the polymer, it is desirable to carry out only water washing without neutralization.

Since the modified product obtained as described above is in a gel state, it is subjected to drying treatment such as sunlight, heating, decompression, centrifugation, and pressing to obtain a polymer material having an ionic group introduced therein. 5).

The water-absorbent resin of the present invention is mainly composed of the above-mentioned polymer materials (1) to (5) into which the ionic groups have been introduced, and further contains a stabilizer.

Various stabilizers can be mentioned. Examples of the stabilizer having an antioxidant effect include the following phenolic, sulfuric, phosphorus-based and others.

<Phenol type> 2,6-di-t-butyl-P-cresol (BHT), butylated hydroxyanisole (BHA), 2,6-di-t-butyl-4-ethylphenol, stearyl- β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tetrakis [methylene-3- (3 ′, 5′-di-tert-butyl-4-hydroxyphenyl) propionate] methane,
2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2,2'-methylene-bis- (4-
Ethyl-6-t-butylphenol), 4,4-thiobis- (3-methyl-6-t-butylphenol), 4,
4'-butylidenebis- (3-methyl-6-t-butylphenol), 3,9-bis [1,1-dimethyl-2-
[Β- (3-t-butyl 4-hydroxy-5-methylphenyl) propionyloxy] ethyl] 2,4,8,1
0-tetraoxaspiro [5,5] undecane, 1,
1,3-tris- (2-methyl-4-hydroxy-5-
t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-
Hydroxybenzyl) benzene, bis [3,3′-bis- (4′-hydroxy-3′-tert-butylphenyl) butyric acid] glycol ester, 1,3,5-
Tris (3 ', 5'-di-tert-butyl-4'-hydroxybenzyl) -S-triazine-2,4,6- (1H,
3H, 5H) trione, triethylene glycol-bis- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate], α-tocopherol (vitamin E), nordihydroguaiaretic acid, butyl Hydroxyanisole, propyl gallate, 2,4
6-tri-t-butylphenol, cyclohexylphenol, 2,6-bis (2'-hydroxy-3'-t-
(Butyl-5'-methylbenzyl) 4-methylphenol, tris (3,5-di-t-butyl-4-hydroxyphenyl) isocyanurate.

<Sulfur>Dilauryl-3,3'-thiodipropionate,dimyristyl-3,3'-thiodipropionate,distearyl-3,3'-thiodipropionate, pentaerythritol tetrakis (3- Lauryl thiopropionate).

<Phosphorus> Triphenyl phosphite, diphenyl isodecyl phosphite phenyl isodecyl phosphite, 4,4'-butylidene-bis (3-methyl-6-t-butylphenyl-di-tridecyl) phosphite, Cyclic neopentanetetraylbis (octadecylphosphite), tris (norylphenyl) phosphite, tris (mono and / or dinolylphenyl) phosphite, diisodecylpentaerythritol diphosphite, 9,10-dihydro-9-oxa -1
0-phosphaphenanthrene-10-oxide, 10
-(3,5-di-tert-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9,10-dihydro- 9-oxa-10-phosphaphenanthrene, tris (2,4-di-t-butylphenyl) phosphite, cyclic neopentanetetrayl bis (2,4-di-t-butylphenyl) phosphite, Cyclic neopentane trail screw (2,
6-di-t-butyl-4-methylphenyl) phosphite, 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite, distearylpentaerythritol diphosphite, tetrakis (2,4 -Di-t-butylphenyl) -4,4'-biphenylene-diphosphite, distearylpentaerythritol diphosphite.

<Others> Erysorbic acid, sodium erysorbate, and isopropyl citrate.

Examples of those having a light stabilizing effect include the following benzophenones, benzotriazoles, hindered amines, cyanoacrylates, salicylates, and oxalic acid anilides.

<Benzophenones> 2,4-hydroxybenzophenone, 2-hydroxy-methoxybenzophenone, 2-hydroxy-octoxybenzophenone,
-Hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2-hydroxy-4-n-dodecyloxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2 , 2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis (2-methoxy-
4-Hydroxy-5-benzoylphenyl) methane.

<Benzotriazole type> 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- [2'-hydroxy-3 ', 5'-bis (α,
α-dimethylbenzyl) phenyl] benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole, 2- (2′-hydroxy-3′-t-butyl-5 '-Methylphenyl)-
5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-amyl) benzotriazole, 2- (2'-hydroxy-3', 5'-di-t-butylphenyl) -5-chlorobenzotriazole, 2-
(2'-hydroxy-5'-t-octylphenyl) benzotriazole, 2,2'-methylenebis [4-
(1,1,3,3-tetramethylbutyl) -6- (2N
-Benzotriazol-2-yl) phenol], 2-
(2'-Hydroxy-5'-t-butylphenyl) benzotriazole.

<Hindered amines (mainly collectively referred to as HALS)> bis- [2,2,6,6-tetramethyl-4-piperidyl] sebacate, bis- [N-methyl-2,2,6 , 6-Tetramethyl-4-piperidyl]
Sebacate, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, bis- (1,2,2,6,6-pentamethyl-4-) Piperidyl) -2- (3,5-di-t-
Butyl-4-hydroxybenzyl) 2-n-butylmalonate, tetrakis- (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, (2 , 2,6,6-tetramethyl-4-piperidyl / tridecyl mixture) -1,2,3,4
-Butanetetracarboxylate, (1,2,2,6,
6-pentamethyl-4-piperidyl / tridecyl mixture)
-1,2,3,4-butanetetracarboxylate,
{2,2,6,6-tetramethyl-4-piperidyl /
β, β, β ′, β′-tetramethyl-3,9- [2,
4,8,10-Tetraoxaspiro (5,5) undecane] diethyl mixed {1,2,3,4-butanetetracarboxylate, {1,2,2,6,6-pentamethyl-
4-piperidyl / β, β, β ′, β′-tetramethyl-
3,9- [2,4,8,10-tetraoxaspiro (5,5) undecane] diethyl mixture {1,2,3,4
-Butanetetracarboxylate, poly [(6- (1,
(1,3,3-tetramethylbutyl) imino-1,3,5
-Triazine-2,4-diyl] [(2,2,6,6-
Tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) iminol].

<Cyanoacrylate>Ethyl-2-cyano-3,3'-diphenylacrylate,2-ethylhexyl-2-cyano-3,3'-diphenylacrylate.

<Salicylate type> Phenyl salicylate, 4-t-butylphenyl salicylate, 4-octylphenyl salicylate.

<Oxalic acid anilide type> 2-
Ethoxy-2'-ethyloxalic acid bisanilide.

The above stabilizers may be contained alone in the water-absorbing resin, or two or more of them may be contained. However, the same system, for example, between antioxidants,
Alternatively, it is preferable to include a different system rather than to include light stabilizers in terms of obtaining a stability effect against various factors (light and heat).

These stabilizers may be directly added to the above-mentioned polymer material having an ionic group, or may be previously contained in a polymer as a raw material when an ionic group is introduced by, for example, an acid treatment. You may. Further, it may be added at the time of producing the water-absorbing resin, or may be added in plural parts at each of the above-mentioned steps.

As a method of directly adding to the water absorbent resin,
A method of blending a stabilizer in a solid state with a water absorbent resin,
Alternatively, a method in which an aqueous solution in which a stabilizer is dispersed or dissolved is absorbed by a water-absorbing resin may be used.

As a method of adding a stabilizer at the time of production, for example, in the case of a water-absorbent resin obtained by graft-polymerizing starch with acrylic acid, the stabilizer is added to the reaction system after neutralization through graft polymerization. Next, it can be manufactured by drying. In the case of a water-absorbing resin of a crosslinked polymer type of sodium acrylate, it can be produced by polymerization with sodium acrylate and a crosslinking agent, followed by addition of a stabilizer and drying. In addition, since many stabilizers trap radicals, if added before polymerization, there is a possibility that polymerization will be inhibited. Therefore, it is preferable to add the stabilizer after polymerization.

As an example in which a stabilizer is previously contained in the raw material polymer, an ABS resin waste material (a resin containing a stabilizer: when the content of the stabilizer is insufficient, additional addition is performed). For example, it can be produced by treating with hot sulfuric acid, washing with water and drying.

That is, when a stabilizer is contained in the raw material polymer in advance, the polymer material containing the stabilizer is subjected to a hydrolysis treatment to introduce an ionic group. For example, when the polymer material is a polymer containing acrylonitrile as a constituent unit, it is hydrolyzed with concentrated sulfuric acid, sulfuric anhydride, fuming sulfuric acid, chlorosulfonic acid, nitric acid, fuming nitric acid, phosphoric acid, phosphorus chloride, phosphorus oxide. An ionic group is introduced by (acid treatment).

Regardless of the production method, the amount of the stabilizer added is 0.00001 to 20% in the water-absorbent resin (dry weight).
% By weight, preferably 0.0001 to 5% by weight.
Is more preferable. If the amount is less than this, the effect of the stabilizer will be insufficient. If the amount is too large, the performance of the water-absorbing resin may be adversely affected, which is disadvantageous in terms of cost.

As described above, by adding the stabilizer to the product or the production of the water-absorbing resin, the heating oxidation and the photo-oxidation reaction are suppressed, and the decrease in the molecular weight of the water-absorbing resin can be suppressed. Becomes Therefore, it is possible to obtain a water-absorbing resin having excellent temporal stability when used outdoors.

[0098]

The present invention will be described below in more detail with reference to examples. It goes without saying that the present invention is not limited to these examples.

Example 1 Case of used personal computer [ABS resin waste material: 48 mol% of styrene unit, 39 mol% of acrylonitrile unit, and 13 mol of butadiene unit as resin composition]
Contains mol%. Stearyl-β- (3,
0.2% by weight of 5-di-t-butyl-4-hydroxyphenyl) propionate. ], Freeze-crushed,
A pulverized material of 65 mesh was used as a resin raw material.

Next, 3 g of this pulverized material was concentrated sulfuric acid (concentration: 9
6% by weight) and reacted at 80 ° C. for 20 minutes. After the completion of the reaction, the solid matter in the system was filtered with a glass filter, washed with water, and dried at 115 ° C. for 2 hours with a circulating drier.

By these operations, a black water absorbing resin was obtained.

The sulfonic acid groups in this water-absorbent resin were 38 mol% of the total monomer units, and the content of the stabilizer was 0.012% by weight (based on dry weight).

Example 2 Guard panel (transparent part) of used 8 mm cassette tape [SAN resin waste material: Resin composition containing 64 mol% of styrene units and 36 mol% of acrylonitrile units. As a stabilizer, tetrakis (2, 2,
6,6-tetramethyl-4-piperidyl-1,2,3
Contains 0.2% by weight of 4-butanetetracarboxylate and 0.1% by weight of stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate. ]
Was pulverized, and a pulverized product of 32 to 65 mesh was used as a resin raw material.

Next, 3.5 g of the pulverized product was added to 90 g of concentrated sulfuric acid (concentration: 89% by weight) and reacted at 60 ° C. for 60 minutes. Then, fuming sulfuric acid (containing 60% by weight of SO ₃ )
An additional 0.5 g was added, and the reaction was further performed for 30 minutes.

After the completion of the reaction, the solid matter in the reaction system was filtered with a glass filter, washed with water, and dried with a dryer for 2 hours. As a result, a transparent water-absorbing resin was obtained.

The sulfonic acid groups in this water-absorbent resin (Example 2) were 47 mol% of the total monomer units, and the content of the former was 0.01% by weight and the content of the latter in the stabilizer was 0.01% by weight. 0.008% by weight (based on dry weight).

[0107] After the third embodiment the starch was treated α of the polymerization concentration is charged so that the starch in 20 weight% / acrylic acid = 20/80 (weight% ratio), Rezokkusu based catalyst (H ₂ O ₂ catalytic amount : 0.1
(Mol%).

After the completion of the polymerization, 70 mol% of the polyacrylic acid was neutralized with sodium hydroxide, and then sodium erythorbate was added to the polymer gel so as to be 0.01% by weight based on the pure polymer. Kneaded.

Thereafter, drying was performed in a dryer to obtain a water-absorbing resin containing a stabilizer.

Example 4 1 g of 1,1,3-tris (2-methyl-4-hydroxy-5) was added to 1 g of a commercially available crosslinked sodium polyacrylate water absorbent resin.
5 g of a 0.001% by weight aqueous solution of (t-butylphenyl) butane was absorbed and then dried to obtain a water-absorbing resin containing a stabilizer.

Example 5 2 g of a 0.002% by weight ethanol solution of phenyl salicylate was absorbed in 1 g of a commercially available polyvinyl alcohol crosslinked water-absorbent resin, and then dried to obtain a water-absorbent resin containing a stabilizer. .

Comparative Example 1 A SAN resin as a reagent (containing 60 mol% of styrene and 40 mol% of acrylonitrile and containing no stabilizer as a resin composition) was pulverized and classified, and was classified into 32-65 mesh. The solid was removed.

This was treated in the same manner as in Example 2 to obtain a transparent water-absorbing resin. The sulfonic acid groups in this water-absorbent resin were 44 mol% of all monomer units. This was designated as Comparative Example 1.

Comparative Example 2 A commercially available starch / sodium acrylate graft type water absorbent resin was used as Comparative Example 2.

Comparative Example 3 A commercially available crosslinked sodium polyacrylate type water-absorbent resin was used as Comparative Example 3.

Comparative Example 4 A commercially available polyvinyl alcohol crosslinked type water absorbent resin was used as Comparative Example 4.

With respect to each of the above water-absorbing resins (Examples 1 to 5 and Comparative Examples 1 to 4), the stability over time was evaluated by the following method.

Evaluation 1 Each of the above water-absorbing resins, and those obtained by swelling them 50 times with pure water, were heated and dried in an oven at 90 ° C. for 100 hours.

After the heat treatment, for the obtained dried product and the water-absorbent resin before drying, the change in water absorption ratio with respect to pure water (reduction ratio of water absorption effect) [(water absorption ratio after heat treatment / water absorption ratio before heating) ) × 100 (%)] was measured and compared. Table 1 shows the results.

[0120]

[Table 1]

As is clear from Table 1, Examples 1 to 5 to which the present invention is applied exhibit superior temporal stability to heat as compared with Comparative Examples 1 to 4.

Evaluation 2 The above water-absorbing resins and those obtained by swelling them 50 times with pure water were irradiated with a 15 W, 100 V UV lamp (distance 50 cm) for 50 hours.

Thereafter, the product obtained after the irradiation treatment and the non-irradiated product were dried under the same conditions (90 ° C., 2 hours), and the difference in the water absorption ratio of the obtained resin with respect to pure water [(irradiated product / (Non-irradiated product) × 100 (%)] was measured and compared. Table 2 shows the results.

[0124]

[Table 2]

As is clear from Table 1, each of Examples 1 to 5 to which the present invention is applied exhibits superior temporal stability to light as compared with Comparative Examples 1 to 4.

[0126]

As is clear from the above description, according to the present invention, it is possible to provide a water-absorbent resin which is excellent in water absorbency and excellent in stability over time against heat and light.
The water-absorbing resin having such properties is suitable for outdoor use such as desert greening, and can greatly expand the application range of the water-absorbing resin.

When the used resin waste material is used as a raw material when producing the water-absorbent resin of the present invention, it is possible to effectively use resources and contribute to global environmental conservation.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08J 3/20 CEZ C08J 3/20 CEZZ

Claims (18)

[Claims] 1. A water-absorbing resin mainly comprising a polymer material into which an ionic group is introduced, and containing a stabilizer. 2. The water-absorbent resin according to claim 1, wherein the content of the stabilizer in a dry weight is 0.00001 to 20% by weight. 3. The water-absorbent resin according to claim 1, wherein the stabilizer is at least one selected from a phenolic antioxidant, a sulfuric antioxidant, and a neighboring antioxidant. 4. The water-absorbent resin according to claim 1, wherein the stabilizer is at least one selected from erythorbic acid, sodium erysorbate, and isopropyl citrate. 5. The light stabilizer according to claim 1, wherein the benzophenone light stabilizer, benzotriazole light stabilizer, hindered amine light stabilizer, cyanoacrylate light stabilizer, salicylate light stabilizer, The water absorbent resin according to claim 1, wherein the water absorbent resin is at least one selected from oxalic acid anilide light stabilizers. 6. The ionic group includes a sulfonic acid group, a chloromethylated amine group, a carboxyl group, a hydroxyl group, -PO
(OH) ₂ group, -CH ₂ PO (OH) ₂ group, according to claim 1, wherein the water-absorbent resin which is characterized in that at least one selected from the group -NO _2. 7. The water-absorbent resin according to claim 1, wherein the polymer material into which the ionic group is introduced contains a crosslinked polymer of polyacrylic acid and / or a salt thereof. 8. The water-absorbing material according to claim 1, wherein the polymer material into which the ionic group has been introduced contains a polymer obtained by graft-polymerizing acrylic acid and / or a salt thereof to starch and / or polyvinyl alcohol. Resin. 9. The water-absorbent resin according to claim 1, wherein the polymer material into which the ionic group has been introduced contains a crosslinked polymer of polyvinyl alcohol. 10. The water-absorbent resin according to claim 1, wherein the polymer material into which the ionic group has been introduced contains a hydrolyzate of a polymer containing acrylonitrile as a constituent unit. 11. The water-absorbing resin according to claim 10, wherein the polymer containing acrylonitrile as a constituent unit contains 2 to 95 mol% of an acrylonitrile unit. 12. The polymer containing acrylonitrile as a constituent unit may be at least one polymer selected from styrene and conjugated dienes in addition to the acrylonitrile unit.
The water-absorbent resin according to claim 10, comprising a seed. 13. The polymer containing acrylonitrile as a constituent unit, wherein the polymer is at least one selected from polyacrylonitrile, acrylonitrile-butadiene-styrene resin, styrene-acrylonitrile resin, and acrylonitrile-butadiene rubber. 10. The water-absorbing resin according to 10. 14. A method for producing a water-absorbent resin, comprising adding a stabilizer to a polymer material into which an ionic group has been introduced in advance. 15. A method for producing an absorbent resin, comprising subjecting a polymer material containing a stabilizer to hydrolysis treatment to introduce an ionic group. 16. The method for producing a water-absorbent resin according to claim 15, wherein the polymer material is a polymer containing acrylonitrile as a constituent unit. 17. The method according to claim 1, wherein the hydrolysis treatment is performed with one or more selected from concentrated sulfuric acid, sulfuric anhydride, fuming sulfuric acid, chlorosulfonic acid, nitric acid, fuming nitric acid, phosphoric acid, phosphorus chloride and phosphorus oxide. 15. The method for producing a water-absorbent resin according to 15. 18. The method for producing a water-absorbent resin according to claim 15, wherein the polymer material containing the stabilizer is a waste material composed of a used resin.