JPS6084360A - Highly water-absorptive high-molecular material composition - Google Patents

Abstract

PURPOSE:To reduce hygroscopicity and fugacity, by blending at least one selected from among a mineral oil, a plasticizer, a dispersant, an inorg. filler and an org. filler with a finely divided highly water-absorptive high-molecular material. CONSTITUTION:A finely divided highly water-absorptive high-molecular material such as a saponified starch/acrylonitrile graft copolymer or a crosslinked product of a salt of an isobutylene/maleic anhydride copolymer, is prepd. At least one member selected from among a mineral oil (e.g. paraffinic process oil or spindle oil) a plasticizer (e.g. dioctyl phthalate or tricresyl phosphate), a dispersant (e.g. liquid paraffin or calcium stearate), an inorg. filler (e.g. talc or calcium carbonate) and an org. filler (e.g. carbon black or pigment) is blended with said high-molecular material to thereby reduce hydroscopicity and fugacity, thus obtaining the desired highly water-absorptive high-molecular material compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fine powder superabsorbent polymer composition. More specifically, it relates to a super absorbent polymer composition with low hygroscopicity σ).

Furthermore, the present invention relates to a superabsorbent polymer composition that prevents scattering due to static electricity and atmospheric currents (wind, etc.).The present inventors have been studying various water-swelling products using superabsorbent polymers for many years. I've done it.

As a result, conventional superabsorbent polymers have major drawbacks.
It was found that there were major obstacles to practical application to water-swellable products.

Generally, water-swellable products are composites of superabsorbent polymers and other substances, such as various resins and rubbers. Some of them may be superabsorbent polymers themselves or water-swellable products (for example, superabsorbent polymer films), and it can be said that there is very little visible appearance overall. Most of them are manufactured by mixing superabsorbent polymers with resins, rubbers, etc., but especially in such applications, the hygroscopicity and scattering properties of superabsorbent polymers have become a big issue.

There is no need to mention that high-grade aqueous polymer IJ is generally considered to have better performance as its water absorption rate and amount increase. Super absorbent polymers with excellent performance can easily absorb all the moisture in the air during storage. Therefore, the method of preserving it is to put it in a bag or container with moisture barrier properties and pierce it tightly, but even that is sometimes insufficient [for example, moisture is absorbed between the production of the superabsorbent polymer and the bagging process]. The super absorbent polymer has often been re-dried immediately before use. However, these methods are very complicated and still have the problem that moisture absorption while the superabsorbent polymer is mixed into the resin or rubber cannot be avoided.

Super absorbent polymers absorb moisture from the surface layer of the powder, making blocking more likely. Therefore, superabsorbent polymers that absorb moisture not only cause bubbles in the product, but also
Blocking causes poor dispersion and becomes foreign matter in the product, significantly degrading the product's appearance, physical properties, and other characteristics. In general, when compounding with resins, combs, etc., the smaller the particle size of the superabsorbent polymer used, the better the physical properties of the final product will be.
It also easily absorbs moisture, making it a practical problem. Water-swellable product production has even been halted during rainy weather. It has been a major challenge to improve the storage stability of superabsorbent polymers without impairing their water absorption performance (preventing moisture absorption), and to prevent moisture absorption during mixing with resins, combs, etc.

There was yet another major problem.

The problem was the scattering of superabsorbent polymers when mixed with resins, combs, etc. In general, the specific gravity of superabsorbent polymers is l fBecause they are fine powders after BJ, they are easily dispersed into the whole air during mixing. If static electricity is generated during mixing, the scattering becomes even more significant, and this becomes a very serious problem, especially when mixing with rubber that tends to generate atomization. As mentioned above, superabsorbent polymers with small particle sizes, which are preferable from the viewpoint of physical properties, are more susceptible to this phenomenon. Therefore, it is essential for workers to wear dust masks, and there is also a work safety problem in that the scattered highly water-absorbent high strength particles fall onto the shop and become slippery when they absorb moisture, causing slipping accidents for workers. Also scattering,
A serious problem arises in that the superabsorbent polymer that has absorbed moisture gets mixed in again during the mixing operation. As described above, preventing the scattering of superabsorbent polymers, especially ultrafine particle superabsorbent polymers, has been a very big issue.

The present inventors have conducted studies on these complex and difficult problems, and have devised the present invention. Specifically, a super absorbent polymer composition is prepared by pre-mixing a super absorbent polymer with a l pusher selected from mineral oil, a L1 agent, a dispersant, an inorganic filler, and a filler. I'm happy with what I got. The super absorbent polymer used in the composition of the present invention will be described in more detail below.
Graph 1 of starch and acrylonitrile - genides of copolymers, starch and acrylic acid (salt) kraft copolymers, salts of styrene maleic anhydride and IC combinations, isophthyn L/N and dla water mashimaleic acid copolymers Crosslinked product, 1tG JI of acrylic acid and/or acrylate
4-coalescence (e.g., self-crosslinking polymer, cross-linked polymer by combination of cross-linking agent, post-cross-linked polymer, etc.)
, salts of reaction products of polyvinyl alcohol and maleic anhydride, kraft comonomers of polyvinyl alcohol and acrylic acid (salts), saponified products of copolymers of vinyl esters and ethylenically unsaturated carboxylic acids or derivatives thereof , saponified copolymers of vinyl esters and unsaturated polycarboxylic acids or their fat derivatives, polyvinyl alcohol crosslinked products, polyethylene glycol crosslinked products, polyethylene glycol crosslinked products, polyvinylpyrrolidone crosslinked products, Examples include crosslinked polyacrylamide, saponified polyacrylonitrile, and mixtures thereof. Among them, superabsorbent polymers, which are polymer electrolytes containing carboxylate salts having a crosslinked structure, are often used because they have a high water absorption capacity and excellent strength after water absorption. In particular, a copolymer composed of vinyl ester (X) and ethylenically unsaturated carboxylic acid or its derivative (Y) with a molar ratio in the range of X:Y = 10:90 to 90:10. Saponified materials have particularly high strength after water absorption, and good weather resistance and heat resistance in the water absorption state.
Therefore, it is widely used because of its excellent performance in the final water-swollen product.

It is preferable that the particles of these superabsorbent polymers be as fine as possible from the viewpoint of physical properties of the final water-swollen product, and the average particle size is desirably less than looμ, particularly preferably less than 50μ.

The composition of the present invention comprises the superabsorbent polymer exemplified above and one or more selected from the group consisting of mineral oil, plasticizer, dispersant, inorganic filler, and organic filler. These mineral oils, plasticizers, dispersants, inorganic fillers, and organic fillers directly or indirectly prevent superabsorbent polymers from coming into contact with the atmosphere, suppress hygroscopicity, and prevent superabsorbent polymers from coming into contact with the atmosphere. In addition to preventing blocking,
Furthermore, it shows the effect of preventing scattering during mixing.

Typical mineral oils include paraffinic process oil, nandene process oil, aroma thread process oil, and spindle oil. As plasticizers, phthalic acid esters such as dioctyl phthalate and dibutyl phthalate, adipic acid esters such as dioctyl adipate, and scalic acid esters such as tricresyl phosphate and trioctyl phosphate are used as dispersants. Paraffin, non-chlorinated rough-in oil, castor oil, linseed oil and other vegetable oils, animal oils, fatty acids and fatty acid salts such as stearic acid and calcium stearate, tributyl titanate and tristearyl titanate, di(okworophosphate) ethylene Examples include organic titanium compounds such as nathanate and mixtures thereof. Furthermore, oil-like substances and liquid substances with low hygroscopicity, such as urethane curing agents and low-molecular-weight liquid polymers such as liquid polybutene, are also contained in the cylinder, and chloroparaffin and ethylene-vinyl acetate co-IL combinations are also contained in the cylinder. ) Mineral oil with a JA strength of 8, ijJ plasticizer, and power powder are also included in the cylinder.

Examples of inorganic fillers include talc, clay, calcium carbonate, silica, etc.;

These tL increasing agents may also contain inhibitors.

1 f! used in the composition of the invention! Mineral oil over It,
The plasticizer, dispersant, inorganic filler, and organic filler are selected in consideration of the method of use and the like. When an inorganic filler or an organic filler is used, the surface of the superabsorbent polymer remains as it is, so the improvement in storage stability is mainly due to the reduction of the superabsorbent polymer in the surface layer due to the dilution effect. Although superabsorbent polymers have a high anti-blocking effect, their storage stability in terms of preventing moisture absorption is slightly inferior to compositions using mineral oil, plasticizers, and dispersants. However, it is superior in terms of ease of handling such as weighing, and in that there is no problem of surface migration (bleeding) of low molecular weight substances in the final water-swollen product produced by mixing with resin or comb. The selection of the type and the amount used are determined in consideration of the compatibility with the S resin, rubber, etc., the mixing method, the desired performance and characteristics of the final water-swollen product, etc.

It is most preferable to select the same mineral oil, plasticizer, dispersant, inorganic filler, and organic filler that are used together with resins, rubbers, etc. when producing water-swellable products. The amount used is mineral oil, plasticizer, dispersant, etc., in the case of liquid, 10% to 500%, particularly preferably 30% to 300% of the superabsorbent polymer, and inorganic fillers and organic In the case of a powder such as an increaser 11 agent, it is used in a proportion of 20 to 2000%, particularly preferably 50 to 1000%.

The composition of the present invention consists of a superabsorbent polymer obtained by polymerization, classification, or pulverization, and one or more selected from mineral oil, plasticizer, dispersant, inorganic filler, and 11 fillers;
The mixing can be carried out mechanically using a blender, mixer, light machine, ball mill, etc., or by mixing in a suitable solvent coexistant such as toluene or ethyl acetate, and then heating and removing the solvent. Sometimes the classification or pulverization of superabsorbent polymers is done using mineral oil or other materials. i] Plastics etc.

It can also be obtained by conducting the experiment in the presence of Furthermore W/#
When producing a finely powdered superabsorbent polymer using a reverse-phase polymerization method, mineral oil, etc. is added to the polymerization dispersion medium at an appropriate point, and after the polymerization is completed, the polymerization dispersion medium is removed by an appropriate method. You can also get it.

The composition of the present invention may contain additives used in resins, combs, etc., such as anti-aging agents, antioxidants, foaming agents, surfactants, cross-linking agents, cross-linking aids, etc., as necessary. In some cases.

The composition of the present invention is composited with resins, combs, etc. and used to produce water-absorbent, water-retaining, and water-swellable products. Saponified polymer, ethylene-isobutylene together, 3: Combined, ethylene-acrylate together: @'4,
Vinyl chloride copolymer, urethane (elastomer foam)
Resin, polyethylene, polypropylene, polyester resin, polyamide resin, acrylic resin, styrene tmtm
, natural comb, isoprene comb, styrene-butadiene comb, ethylene-α-olefin copolymer, ethylene-α-olefin-non-functional diene copolymer, butadiene rubber, chlorobutene rubber, acrylic rubber, acrylonitrile-butadiene rubber, etc. Illustrated.

The composition of the present invention consists of a resin, a com, etc., carbon fluff, a white filler, an oil, a plasticizer, a cross-polishing agent, a cross-linking aid, an anti-aging agent, a processing aid, etc. selected as necessary. After mixing with agents, pigments, etc. using an extruder equipped with a roll, kneader, Banbury, Talmage screw, etc., molding, crosslinking, etc. are performed.

By using the composition of the present invention, foreign matter and abnormal abrasion of poorly dispersed superabsorbent polymers can be avoided (A water absorption, water retention, water swelling products, such as water sealing products, etc.) (nokink, seal tape,
Construction, medical hygiene, drying, etc. can be achieved with high work efficiency and a good working environment. In particular, compared to F + I fat, it takes a long time to mix, and the addition of super absorbent Shokai E is a small force that can be ladled in an oven roll) - it is not only bulky but also generates static electricity. The compositions of the present invention are especially useful in the production of comb products.

Examples of the present invention will be shown below, but the present invention is not limited to these examples.

Example 1 Adding 0.1y of lauroyl oxide as a polymerization initiator to vinyl acetate 61 and methyl acrylate 402,
Partially saponified polyvinyl alcohol 8y- and NaCJ l
The mixture was dispersed in 800ml of water containing 09-, and suspension polymerized at 65°C for 6 hours. 20θg of this copolymer 869-
-Mekutsu-# Oft O) Water oyohi 5N hbiOH 40ml! suspended in a saponification solution consisting of 2
Saponification reaction was carried out at 5°C for 1 hour and then at 65°C for 5 hours. After thoroughly washing with methanol, drying under reduced pressure yields a spherical dry saponified product with an average particle size of 200μ (water absorption capacity is 700μ).
'17'? −) was obtained. This was ground in a Geno 1-mill to obtain a finely powdered superabsorbent polymer having a particle size of 60 μm or less.

This is mixed with rough-in yarn and process oil using a blender to obtain the composition of the present invention.

Each composition was left in an atmosphere with a relative humidity of 60% for 12 hours,
The storage stability against humidity of this popular product was investigated and the results are shown below.

Next, we will describe a study example in which the composition of the present invention was applied to a water-swellable sealant using ethylene propylene comb.

100 parts by weight of Nisprene 400 (ethylene propylene rubber made by Sumitomo Chemical), 200 parts by weight of clay, and 100 parts by weight or 88 parts by weight of paraffin oil were prepared using Banbury and rolled into a 10-inch roll. The composition-2 of the present invention or a super absorbent polymer for comparison was mixed. However, the water-absorbing polymer or the composition of the present invention that was scattered and fallen due to static electricity during mixing was collected by the group.

The dropped comparative superabsorbent polymer absorbed moisture in the air on the paper it was received on, and exhibited some blocking properties.

After measuring the weight of the scattered and fallen objects in both cases, the scattered and fallen objects were completely mixed with the sealant raw material and extruded into 2 x 20' pieces using an extruder.
It was molded into an IvL ribbon extrudate.

In the sealant extrusion product using the comparative superabsorbent polymer, a large number of superabsorbent polymers that fell during mixing, absorbed moisture, and blocked were scattered as foreign particles, and the extruded surface appearance was extremely poor.

Further, when this extruded product was left in water for one day, the foreign material portion swelled abnormally and exhibited a marked unevenness. On the other hand, the surface of the sealant extrudate using Composition-2 of the present invention was smooth and good, and the surface after being left in water for one day also showed smooth and uniform swelling.

As is clear from the above, the composition of the present invention not only has excellent storage stability, but also has a short mixing time with resin and rubber (in the case of the comparative superabsorbent polymer, the roll bank part is The sealant raw materials become lumps and do not get caught in the rolls, so it takes a very long time to mix them), and there is no blocking property when absorbing moisture, and we manufacture various products with good water absorption, water retention, and water swelling properties, such as water swelling sealants. It makes it seem possible.

In particular, when mixed with a comb, the water-absorbing polymer is charged by the static electricity generated during mixing and scatters in all directions, but the composition of the present invention does not have this, and this point alone makes the composition of the present invention meaningful. Thick.

Example 2 To 100 parts by weight of the same fine particulate super absorbent polymer as in Example 1,
Lo o talc: L! The composition of the present invention was obtained by mixing using a filtration machine.

The composition of the present invention was allowed to release for 12 hours at a relative humidity of 60+. As a result of measuring the weight increase and calculating the ratio to the super absorbent polymer MUI in the composition, the weight increase of the composition of the present invention was 9 yen.

Next, Nisblen 601A (ethylene propylene rubber made by Sumitomo Chemical) 100 parts by weight, comb/-85 parts by weight, carbon black 5 parts, paraffin oil 30 parts by weight, zinc white 5 parts by weight, stearic acid 1 part by weight, vulcanization acceleration 4 parts of agent (
BZ / TT / 'l' pasting / M work 210.510.5
3 parts by weight of the composition of the present invention after moisture absorption was added to a blend of ethylene propylene comb containing 0.75 parts of sulfur and 0.75 parts of sulfur using a roll trowel, and vulcanization was performed at 160°C for 7 minutes. The surface condition of the product was good.

On the other hand, add 1 talc to the above ethylene propylene rubber compound.
2.8 parts by weight of the comparative fine powder super absorbent polymer obtained in Example 1 was added by roll to 5 parts - 1 η parts, and vulcanization was performed at 160°C for 7 minutes. The material had many coarse air bubbles, and inside the air bubbles there were white foreign substances that may be due to poor dispersion of the superabsorbent polymer.

The composition of the present invention is diluted with an inorganic filler called talc, which suppresses hygroscopicity and improves storage stability (however, it is not as effective as the oil in Example 1).
Since large local moisture absorption can be prevented by dilution, no foaming phenomenon is observed in the vulcanizate. On the other hand, in the case of only a superabsorbent polymer, moisture absorption is significant and floraking occurs due to moisture absorption, so the dispersibility in ethylene propylene comb formulations is poor, and even when compared with the composition of the present invention at the same moisture content, it is localized. Bubbles are formed due to the presence of a large amount of water.

Claims (1)

[Scope of Claims] l) Comprised of a finely powdered superabsorbent polymer and at least one of mineral oil, a plasticizer, a dispersant, an inorganic thickener, and an organic thickener, and has hygroscopic and scattering properties. A superabsorbent polymer composition that is characterized by being designed to prevent. 2) The high-quality resin according to claim 1 is characterized in that it prevents moisture absorption during storage, moisture absorption during mixing with resin or rubber, and scattering due to static electricity generated during mixing with resin or rubber. Water-absorbing polymer composition. 8) The super absorbent polymer composition according to claim 1 or 2, wherein the super absorbent polymer is a polymer electrolyte having a crosslinked structure containing a carboxylic acid and/or a salt thereof. 4) The superabsorbent polymer is composed of vinyl ester (X) and ethylenically unsaturated carboxylic acid or its derivative (Y) as main components, with a molar ratio of X:Y=IO: 90 to 90:10. The superabsorbent polymer composition according to claim 1, 2 or 3, which is a saponified product of copolymerization. 5) The superabsorbent polymer composition according to claim 1, fJS 2, 3, or 4, wherein the average particle size of the superabsorbent polymer is 100μ or less, 6) Water-swellable comb product The superabsorbent polymer composition according to claim 1, 2, 3, 4, or 5, characterized in that it is used for M addition.