JPH0673243A - Water-absorbing resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin compsn. excellent in moldability, flexibility, water absorption properties, etc., and in productivity since it does not require vulcanization. CONSTITUTION:100 pts.wt. olefinic thermoplastic elastomer comprising 15-55wt.% polyethylene and 85-45wt.% ethylene-propylene-diene terpolymer is compounded with 10-100 pts.wt. hydrogenated diene copolymer to give a polymer component. 100 pts.wt. the polymer component is compounded with 5-95 pts.wt. waterabsorbing resin, 1-25 pts.wt. inorg. filler, 2-50 pts.wt. softener, and 2-50 pts.wt. plasticizer to give the objective resin compsn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-absorbent resin composition containing a water-swellable polymer water-absorbing agent and an olefinic thermoplastic elastomer. More specifically, it is useful as a waterproof seal between segments of tunnels and water and sewerage construction, civil engineering such as seals for exterior wall panels of buildings, waterproofing material for construction work, and anti-condensation material that also has an anti-seismic function. The present invention relates to a composition in which a water absorbent resin is mixed with an olefin-based thermoplastic elastomer.

[0002]

2. Description of the Related Art Conventional sealing materials for waterproofing between tunnels and waterworks / sewerage segments have been crosslinked polyacrylates, starch-polyacrylate resins, vinyl alcohol copolymers or anhydrous. A water-swellable composition in which a superabsorbent resin such as a resin obtained by crosslinking a reaction product of a maleic acid copolymer and a basic substance is blended with a diene rubber or the like and vulcanized is widely used. Kaisho
57-108143, 57-135160, etc.). However, since this water absorbent resin composition requires a vulcanization step, there are problems such as an increase in molding cost and a decrease in productivity.

Further, a water-absorbent resin composition containing a thermoplastic resin containing a highly water-absorbent resin, for example, a water-absorbent polymer finely divided into 100 parts by weight of ethylene-vinyl acetate copolymer or polybutadiene (lower olefin-maleic anhydride). Cross-linked with urea resin or melamine resin) 10
To 300 parts by weight (Japanese Patent Laid-Open No. 55-3424), 100 parts by weight of a composition of 30 to 95% by weight of chlorinated polyethylene and 70 to 5% by weight of polyisobutylene in a super absorbent resin (maleic anhydride). Acid-isobutylene copolymer, acrylic acid-vinyl alcohol copolymer, etc.) 15 to 10
A mixture of 0 parts by weight (Japanese Patent Laid-Open No. 62-106879) and the like have been proposed, but the former has a large temperature dependency and has a problem in workability due to low water absorption and flexibility especially at low temperatures. However, the latter has the problem that hydrogen chloride is generated during incineration. Therefore, an object of the present invention is to provide a chlorine-free, non-vulcanized type water-absorbent resin composition which is excellent in physical properties such as moldability, flexibility and water absorbency and productivity.

[0004]

In order to solve the above-mentioned problems, the present inventors diligently studied a non-vulcanized type water-absorbent resin composition based on an olefinic thermoplastic elastomer, and made a polyethylene-based polymer. And a resin composition in which a water-absorbent resin, a softening agent and a plasticizer are mixed with an olefinic thermoplastic elastomer composed of an ethylene-propylene-diene copolymer and the resin composition is excellent in flexibility and molding processability, and each component described above. The composition in which the inorganic filler is mixed with the water-absorbent resin composition has good dispersibility in the composition and becomes an excellent water-absorbent resin composition, and when the latter composition is foamed at a low ratio, the amount of the softening agent is increased. The inventors have found that even with a small amount, the water absorption capacity (water absorption speed and water absorption ratio) is improved, and the flexibility and molding processability are excellent, and patents have been applied for each. As a result of further studies, the present inventors have found that when a hydrogenated diene-based copolymer is added to each of the above components, the water absorption capacity is improved without foaming, and the flexibility, water absorption, and molding processability are excellent. The present invention has been completed.

That is, the present invention relates to (a) 100 parts by weight of an olefinic thermoplastic elastomer comprising 15 to 55% by weight of a polyethylene polymer and 85 to 45% by weight of an ethylene-propylene-diene copolymer ( b) 10 to 100 parts by weight of hydrogenated diene-based copolymer, and (c) 5 to 95 parts by weight of water-absorbent resin, and (d) inorganic filler 1 to 100 parts by weight of the components (a) + (b) ~ 25 parts by weight,
(E) 2 to 50 parts by weight of softening agent and (f) 2 to 5 of plasticizer
The water-absorbent resin composition is characterized by containing 0 part by weight. Hereinafter, the water absorbent resin composition of the present invention will be described.

The olefinic thermoplastic elastomer (a) which is the base of the water absorbent resin of the present invention is a composition comprising a polyethylene polymer (first component) and an ethylene-propylene-diene copolymer (second component). Is. Here first
As the polyethylene-based polymer as a component, a homopolymer of ethylene, a copolymer of ethylene and propylene or another α-olefin, or ethylene and vinyl acetate,
It is possible to use copolymerization with ethyl acrylate or the like, or homopolymers thereof, or blends of homopolymers and copolymers. Specifically, polyethylene and ethylene-vinyl acetate copolymer are preferable.

As polyethylene, the melt index (MI, JISK7210, load 2.16 kg) is 0.01 to 100 g /
It preferably has a density of 0.910 to 0.935 g / cm ³ for 10 minutes. The polyethylene also includes those obtained by copolymerizing α-olefins having about 4 to 20 carbon atoms up to about 20 mol% or less. As the ethylene-vinyl acetate copolymer (EVA), a copolymer having a vinyl acetate content of 10 to 30% by weight is preferable, and a vinyl acetate content of 1 is particularly preferable.
Those in the range of 7 to 30% by weight are preferable. The melt index (190 ° C., 2.16 kg load) of such EVA is preferably 15 to 25 g / 10 minutes. As the polyethylene-based polymer, an ethylene-vinyl acetate copolymer (EVA) is most preferable.

Olefinic thermoplastic elastomer (a)
The second component, ethylene-propylene-diene copolymer (EPDM), is a copolymer composed of ethylene, propylene and a diene.

Examples of the diene compound include ethylidene norbornene, 1,4-hexadiene and dicyclopentadiene. The EPDM has an ethylene content of 50 to 60 mol% and a propylene content of 20 to 30.
Those having a mol%, a diene compound content of 1 to 20 mol% and an iodine value of 1 to 30 are preferable. Mooney viscosity (ML _{1 + 4} , 100 ° C) of EPDM is 20-100
Is preferable, and 50 to 90 is particularly preferable.

The blending ratio of the polyethylene polymer and the ethylene-propylene-diene copolymer (EPDM) is 15 to 55% by weight, preferably 20 to 50% by weight, and 85 to 45% by weight EPDM. %, Preferably 80 to 50% by weight. If the polyethylene-based polymer is less than 15% by weight, the mechanical strength and moldability will decrease, while if the polyethylene-based polymer exceeds 55% by weight, the hardness will increase and the tear strength will decrease.

Olefinic thermoplastic elastomer (a)
Is produced by melt-kneading the polyethylene polymer and EPDM in the above proportions. That is, 15 to 55% by weight of the polyethylene polymer and 85 to 45% by weight of EPDM are kneaded by a kneading machine such as a twin-screw extruder, a single-screw extruder, a roll kneader, a Banbury mixer, and a Brabender. The kneading temperature may be appropriately set to a temperature at which the resin component serving as the base is melted or higher, but it is usually preferably in the range of 90 to 250 ° C. The melt index of the olefinic thermoplastic elastomer composition thus obtained (190
C., 2.16 kg load) is preferably 0.5 to 20 g / 10 minutes.

In the present invention, the olefinic thermoplastic elastomer (a) is a polyethylene polymer and EPDM.
As independent components, the hydrogenated diene copolymer (b), the water-absorbent resin component (c), the inorganic filler (d), the softening agent (e) and the plasticizer (f), which will be described later, may be used together or at any time. It can also be prepared by kneading in order.

The water absorbent resin composition of the present invention contains (b) a hydrogenated diene copolymer in order to improve water absorption.
The hydrogenated diene copolymer comprises a vinyl aromatic compound polymer block (A) and a conjugated diene polymer or a random copolymer block of a vinyl aromatic compound and a conjugated diene (B)- (B) Block copolymer, or (A)-(B)-(C), which is composed of a vinyl aromatic compound and optionally a tapered block (C) in which the vinyl aromatic compound is gradually increased among conjugated dienes. A block copolymer or a (A)-(B)-(A) block copolymer composed of a vinyl aromatic polymer (A), which is hydrogenated to obtain at least a double bond of a conjugated diene moiety. 80% saturated, number average molecular weight 50,000-60
It shows the whole. These are disclosed in JP-A-3-72512. The hydrogenated diene-based copolymer,
Those having a bound styrene content of 10 to 30% by weight and a melt flow rate (230 ° C., 2.16 kg load) of 3 to 6 g / 10 minutes are preferable.

As the water-absorbent resin (c) in the resin composition of the present invention, those which are commercially available as super-water-absorbent resins can be used without particular limitation, and a carboxyl group or a group capable of being induced to a carboxyl group is intramolecularly used. A highly water-absorbent resin obtained by crosslinking a polymer containing one or two α, β-unsaturated compounds as a monomer component with a crosslinking agent is preferable, and the particle diameter is preferably 5 to 30 μm. 1
It is 0 to 20 μm.

Examples of such water-absorbent resins include polyacrylate-based resins, starch-acrylate-grafted polymers, vinyl acetate copolymers, maleic anhydride copolymers and vinyl alcohol-based copolymers. Named
Above all, a polyacrylate resin can be preferably used. The water-absorbent resin has a water absorption rate of 10 to 5 of its own weight.
It is desirable to have a water absorption capacity of 00 times, preferably 50 to 200 times.

In the composition of the present invention, the inorganic filler (d)
By using, the dispersibility of the water absorbent resin in the composition is improved, and it is not necessary to use a compatibilizer.
Here, as the inorganic filler (d), talc, calcium carbonate, gypsum, carbon black, clay, kaolin, silica, diatomaceous earth, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, calcium sulfate, calcium phosphate, aluminum hydroxide, Zinc oxide, magnesium hydroxide, calcium oxide, magnesium oxide, titanium oxide, alumina, mica, shirasu balloon, zeolite, silicate clay, cement, silica fume, mica powder and the like can be used, among which talc, calcium carbonate, silica. Is preferred. These inorganic fillers can be used in various shapes such as powder, sphere and flake.

In the composition of the present invention, a softening agent (e) and a plasticizer (f) are added in order to improve the flexibility at low temperature, the powdering property and the workability.

As the softening agent (e), a mineral oil softening agent is preferably used. Examples of the mineral-based softening agent include petroleum-based softening agents such as paraffin-based, naphthene-based and aromatic-based, polymerized high-boiling strong aromatic oil, liquid paraffin, white oil, etc., but preferably petroleum-based softening agent A paraffinic petroleum softener having a good compatibility with an agent, particularly EPDM can be preferably used.

As the plasticizer (f), those usually used in resin compositions can be used, and for example, a phthalic acid derivative can be preferably used. As a phthalic acid derivative,
Dimethyl phthalate, di- (2-ethylhexyl) phthalate, diethyl phthalate, dibutyl phthalate, di-n-octyl phthalate, diisooctyl phthalate, diisobutyl phthalate, diheptyl phthalate,
Diphenyl phthalate, diisodecyl phthalate, ditridecyl phthalate, diundecyl phthalate, benzyl phthalate, butyl benzyl phthalate, dinonyl phthalate, alkyl benzyl phthalate, dimethoxy ethyl phthalate, dimethyl cyclohexyl phthalate,
Methyl phthalyl ethyl glycolate, ethyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate and a mixture thereof and the like can be mentioned.

In the present invention, in addition to the above-mentioned components, if desired, an ultraviolet absorber, a heat stabilizer, a light stabilizer, a flame retardant, an antistatic agent, a nucleating agent, etc. may be appropriately added.

The above olefinic thermoplastic elastomer component (a), hydrogenated diene copolymer (b), water absorbent resin component (c), inorganic filler (d), softening agent (e) in the composition of the present invention. And, the blending ratio of the plasticizer (f) is 1 part of the component (a) to 100 parts by weight of the component (a).
0 to 100 parts by weight, preferably 20 to 40 parts by weight, with respect to 100 parts by weight of the above components (a) + (b), the component (c)
Is 5 to 95 parts by weight, preferably 30 to 60 parts by weight, component (d) is 1 to 25 parts by weight, preferably 3 to 15 parts by weight,
20 to 50 parts by weight of component (e), preferably 30 to 45
Parts by weight and 2 to 50 parts by weight of the component (f) are blended.

When the amount of the component (b) is less than 10 parts by weight, the water absorption of the composition is insufficiently improved, and when it exceeds 100 parts by weight, the weight retention becomes low. When the ratio of the water absorbent resin (c) is less than 5 parts by weight, the water absorption of the composition becomes insufficient,
Further, if it exceeds 95 parts by weight, the mechanical strength of the composition is lowered. When the proportion of the inorganic filler (d) is less than 1 part by weight, the dispersibility of the water absorbent resin is lowered and the water absorption becomes insufficient, and when it exceeds 25 parts by weight, the flexibility is lowered.
When the proportion of the softening agent (e) is less than 2 parts by weight, the flexibility is insufficient, and when it exceeds 50 parts by weight, moldability becomes poor. Further, when the proportion of the plasticizer (f) exceeds 50 parts by weight, the kneading work becomes difficult.

The water absorbent resin composition of the present invention comprises an olefinic thermoplastic elastomer component (a), a hydrogenated diene copolymer (b), a water absorbent resin component (c), an inorganic filler (d) and a softening agent. (E) and the plasticizer (f) are prepared by melt-kneading the respective components in the above-mentioned proportions in any order. However, in order to improve the uniform dispersibility of the water-absorbent resin in the composition, a polyethylene-based polymer and EPDM are previously prepared.
It is preferable to premix the olefinic thermoplastic elastomer component (a) and the water-absorbent resin (c) prepared from the above with a stirrer such as a Henschel mixer. Ingredients (b), (d), (e) and (f) were added to this premix and a single screw extruder, twin screw extruder, Banbury mixer,
The melting temperature may be appropriately set at a temperature above the temperature at which the resin component is melted by using a kneading machine such as a kneading roll, a Brabender, and a kneader ruder, but the water-absorbent resin is preferably formed by heating and melting at 90 to 250 ° C. It is possible to obtain a water-absorbent resin composition that has been mixed with good dispersibility.

[0024]

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 description. In addition, in each of Examples and Comparative Examples, the following materials were used as the resin raw material and the additive.

Olefinic thermoplastic elastomer: EP
DM (propylene content 28% by weight, iodine value 15, Mooney viscosity (ML _{1 + 4} , 100 ° C.) 88) and EVA
(Vinyl acetate content 28% by weight, melt index (190 ° C., 2.16 kg load) 20 g / 10 min) and at a ratio shown in Table 1 at room temperature using a Henschel mixer, premixed, and then at about 120 ° C. Roll-kneaded and pelletized.

Hydrogenated diene copolymer: Dynaron 1320P
(Product name) (Nippon Synthetic Rubber Co., Ltd., bound styrene content 10%, melt flow rate (230 ° C, 2.16 kg load)
3.5 g / 10 minutes, Shore A hardness 39, hydrogenation rate 99%
that's all. Water absorbent resin: Aqualic CS-6S (manufactured by Nippon Shokubai Chemical Co., Ltd .; polyacrylate type) Inorganic filler: Talc (manufactured by Hayashi Kasei Co., Ltd .; Micron White 5000A, average particle size 6 μm) Softener: Mineral oil ( Idemitsu Petrochemical Co., Ltd .; PW-38
0 (trade name) Paraffin mineral oil) Plasticizer: DIDP (diisodecyl phthalate)

Examples 1 to 3 and Comparative Examples 1 to 2 The olefinic thermoplastic elastomer and the water absorbent resin were premixed at room temperature using a Henschel mixer, and then the hydrogenated diene copolymer was used. , Inorganic filler, softener and plasticizer using a Brabender kneader
Melt-kneading at 0 ° C. to obtain a sheet having a thickness of about 1 mm. Table 1 shows the results of measuring the hardness (Shore A) of each polyolefin-based water absorbent resin composition, the water absorption capacity after 1 day and 7 days, and the weight retention rate.

[0028]

[Table 1]

The methods of measuring the physical properties and the methods of evaluating the workability shown in Table 1 are as follows. (1) Hardness: Measured with a rubber hardness meter (Shore A) (JISK63
Complies with 01). (2) Water absorption capacity (after 1 day and 7 days): A value obtained by dividing the weight of the resin foam after water absorption by the weight of the resin foam before water absorption. (3) Weight retention rate: A value obtained by weighing what was once swelled, then weighing, and dividing the weight by the weight before swelling. The smaller this value is, the more gel is removed from the water absorbent resin.

As is clear from Table 1, the compositions of the present invention (Examples 1 to 3) all have a hardness (Shore A) of 50 or less, are excellent in flexibility, and have good workability. Also, the water absorption capacity after 7 days is good, and the weight retention rate is also sufficient. On the other hand, Comparative Example 1 containing a small amount of the hydrogenated diene copolymer had a low water absorption capacity after 7 days, and Comparative Example 2 containing a large amount of the hydrogenated diene copolymer had a weight retention rate. Will fall.

[0031]

The water-absorbent resin composition of the present invention comprises a olefin-based thermoplastic elastomer as a base resin and a specific amount of a hydrogenated diene-based copolymer, a water-absorbent resin, an inorganic filler,
It is a blend of a softening agent and a plasticizer, and because it is thermoplastic, it can be easily molded into any shape by methods such as sheet molding and profile extrusion molding, and it has excellent flexibility and workability at low temperatures. Has a good water absorption capacity without using a foam, and does not require a vulcanization step and has excellent productivity. Such a composition of the present invention is a waterproof seal between segments of tunnels and water supply and sewerage construction, civil engineering such as a seal of a gap of a building outer wall panel, a water stop material for construction work, a dew condensation preventing material also serving as an anti-seismic function, Furthermore, it can be used as a water retention material for agriculture and forestry and horticulture.

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C08L 53/02 LLY 7142-4J

Claims (1)

[Claims] 1. (a) Polyethylene polymer 15-55
Wt% and ethylene-propylene-diene copolymer 85-
45 parts by weight of 100 parts by weight of the olefin-based thermoplastic elastomer, 10 to 100 parts by weight of the hydrogenated diene-based copolymer (b) is contained, and the component (a) + (b) 1
(C) 5 to 95 parts by weight of water-absorbent resin with respect to 00 parts by weight,
(D) 1 to 25 parts by weight of inorganic filler, (e) softener 2 to
A water-absorbent resin composition comprising 50 parts by weight and (f) 2 to 50 parts by weight of a plasticizer.