JPS60258237A - Resin composition swelling with water - Google Patents

Abstract

PURPOSE:A composition that is obtained by adding a nonionic surfactant of ethylene oxide condensation product to a mixture of a high water-absorbing resin and an elastomer, thus giving moldings good in both water absorption and rapid expansion by extrusion. CONSTITUTION:100pts.wt. of a resin composition containing a high water-absorption resin and an elastomer, are added to 0.5-20pts.wt. of a nonionic surfactant of ethylene oxide polycondensation product. The weight ratio of the water-absorption polymer to the elastomer is 30/70-70/30. An example of the nonionic surfactant is water-soluble polyoxyethylene alkyl ether.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is suitable for a wide range of applications such as industrial materials, agricultural materials, civil engineering and construction materials, toys, medical-related products, etc., and has excellent water absorption ability and absorbs water. This invention relates to a water-swellable resin composition that has the ability to release.

BACKGROUND OF THE INVENTION Superabsorbent resins, which have the ability to absorb several hundred times more water than their own weight, are well known and are attracting attention for their uses as sanitary materials and geological improvement agents.

Furthermore, superabsorbent resins are generally in powder form.

It is expected to be used in molded products by blending it with elastomers, that is, synthetic resins and rubbers, and adding plasticizers, lubricants, etc.

However, if a super absorbent resin is simply blended with an elastomer and molded into a molded product by extrusion or injection molding, not only will it not be possible to obtain the expected water absorption ability, but it will also quickly absorb water when it comes into contact with water. The property of superabsorbent resins, which is swelling, cannot be exhibited, and this tendency is particularly noticeable in molded products made by injection molding.

Problems to be Solved by the Invention The present invention eliminates the disadvantages of poor water absorption ability and poor rapid expansion properties of elastomers blended with super absorbent resin and molded by injection molding, and provides an excellent solution. Water absorption and @
The object of the present invention is to provide a water-swellable resin composition that can be used to produce molded articles with rapid expansion properties and is therefore expected to be put to practical use in a wide range of fields.

Means for Solving the Problems In the present invention, the above-mentioned problems are solved by adding an ethylene oxide metal condensate-based nonionic surfactant to a resin composition in which a super absorbent resin is blended with an elastomer. Resolved the point.

However, molded products made from conventional resin compositions tend to have an elastomer coating formed on their surfaces.

As a result of observation, it was found that this was what was preventing water from penetrating. The present invention was completed based on the discovery that an ethylene oxide condensate-based nonionic surfactant is effective as an additive that does not inhibit moldability and gives the surface coating an excellent affinity for water. It is something.

Embodiment 1 As the superabsorbent resin constituting the water-swellable resin composition of the present invention, known resins broadly classified into starch type, cellulose type, and synthetic polymer type can be used. All of these are made by cross-linking a part of the molecules of water-soluble resins to give them hydrophilicity and high osmotic pressure. Craft polymers with acrylic acid, acrylamide, vinyl acetate, etc.1 Synthetic polymers include modified polyvinyl alcohol, crosslinked polyacrylic acid, copolymers of acrylic acid with polyfunctional monomers and hydrophobic monomers, and copolymers of vinyl alcohol with acrylic acid esters. An example is a block copolymer.

Elastomers to which the superabsorbent resin is blended include thermoplastic synthetic resins such as vinyl chloride resin, urethane resin, ethylene/vinyl acetate copolymer, ethylene/propylene copolymer, natural rubber, and chloropyrene.

Rubber such as FPDM is exemplified.

It is obvious that increasing the blending ratio of super absorbent resin will improve the expandability, but if the blending ratio is extremely increased, the moldability will decrease, so take into consideration the expandability and moldability. The blending ratio of water absorbent resin and elastomer is 3 by weight.
o: 70 to 70: 30 preferably 50:
The range is from so to about 6:4o.

Next, examples of nonionic surfactants based on ethylene oxide condensates include polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, polyoxyethylene sorbitan fatty acid ester, and polyoxyethylene 7
Examples include fatty acid esters, oxyethylene/oxypropylene proteases, cupolymers, and polyoxyethylene alkylamines.

Here, as an index when using a surfactant, it is convenient to quantify the balance between the hydrophilic part and lipophilic part contained in the molecule, and use it as an index of the degree of surface activity and solubility. It is accepted. This indicator is HLB (H
hydrophile Lipophile Ba1an
ce).

Among nonionic surfactants, those with HLB = 1θ to 2o are water-soluble, those with HLB = 5 to 9 are water-dispersible,
Surfactants with HLB = 1 to 4 are oil-soluble and therefore, surfactants suitable for the present invention are those with HLB = 10 to 20, and the resin composition to which this is added has a small HLB when in contact with water. It is easily understood that it expands rapidly compared to other materials.

Incidentally, such a surfactant is used in an amount of 0.00% based on 100 parts by weight of the resin composition consisting of a superabsorbent resin and an elastomer.
5 to 20. Preferably, it is added at a ratio of 1 to 15. If the amount is less than 0.5, it will not contribute to improving expansion properties, and if the amount is more than 20, the expansion rate will reach saturation and no more should be added. It is also uneconomical.

Furthermore, auxiliaries used in general molding such as plasticizers, stabilizers, and fillers are added as molding aids, and pigments and blowing agents may also be added depending on the purpose.

Next, test results of the present invention will be described.

All samples were made using 8-inch diameter rolls at a roll temperature of 120±5.
First, the elastomer was kneaded for 2 minutes at 1. □, then the super absorbent resin and others were added and kneaded for another 5 minutes, and then the temperature at the front of the cylinder was 150°C using a Nissei Plastics injection molding machine (Model Ts-200). , rear temperature 160℃, nozzle temperature 1
120 x 15 x 4 under the conditions of 60°C, injection pressure 5-80"Q, injection time 5-7 seconds, and cooling time 20 seconds.
It was manufactured by molding it into a size (U) and cutting it into a length of 50111 mm.

The swelling property was measured by immersing the sample in water at room temperature and tracking the change in weight over time, and expressing it as a weight magnification.

It was. The moldability was evaluated by roll kneading property and mold releasability from the mold. Roll crosstalk is caused by the roll surface l＼
Items that have poor adhesion resistance and are difficult to organize as banks
Those that can be freely cut and crossed on the roll surface and are easy to organize into banks are marked as ○, and those that are particularly good are marked as ◎. The releasability from the mold is defined as X if the molded product is difficult to separate from the mold and powdery substances remain on the mold surface after peeling.

Mark as ○ if it is easy to separate and the mold surface is clean.

Particularly good ones were marked as ◎.

Furthermore, in tests 1 and 4, hardness (JISA 0 seconds) was used as a reference.
, tensile elongation (sample) was measured.

First, the samples for Tests 1 and 2 were a vinyl alcohol-acrylic acid ester copolymer (Sumitomo Chemical Co., Ltd., trade name Sumikagel 5p-s'2o) as a super absorbent resin, and an ethylene-propylene copolymer (Sumitomo Chemical Co., Ltd., product name Sumikagel 5p-s'2o) as an elastomer. (product name: S-Puren 512B), and 100 each of Jc.
(parts by weight) and liquid paraffin 30. A resin composition was composed of dioctyl adipate IQ and stearic acid 1 (parts by weight).

(Test 1) Polyoxyethylene sorbitan monostearate (HLB=14.9) was used as a surfactant.

Polyquine ethylene sorbitan monooleate (HLR
Implementation of the present invention in which 5 (parts by weight) of polyethylene glycol monostearate (HLB = 15.0), polyethylene glycol monostearate (HLB = 13.4), and polyoxyethylene lauryl ether (HLB = 10.5) were each added to the resin composition. Example A,
B, C, D.

Comparative Example a in which no surfactant was added and sorbitan monostearate (HLB = 4.7), sorbitan monooleate (HLB = 4.3), and stearic acid mo/glyceride (HLB = 2.8) were used in the resin composition. Comparative Examples A, C, A, and A were each added with 5 (parts by weight) of glycerin.

Comparative example in which 10 (parts by weight) of polyethylene glycol was added to the resin composition.
Shown in the figure (values are multiplied by weight).

(Test 2) The blending ratio of polyoxyethylene sorbitan monooleate, which had the best expandability as a result of Test 1, was varied, and 0, 2, and 5°15 (parts by weight) of each were added to the resin composition. The following table and FIG. 2 show the results of weighing the swelling properties of Examples E, F, G, and H of the present invention depending on the water immersion time.

(Test 3) Ethylene-vinyl acetate copolymer (manufactured by Inu Nippon Ink Chemical Industry Co., Ltd., trade name Evasurene 4] Op) was selected as the same superabsorbent resin and elastomer as above, and 100 (parts by weight) of each of them and dioctyl phthalate were added. 20. Polyethylene glycol 30. 5 (parts by weight) of polyoxyethylene rubitan monostearate was added to a resin composition composed of 2° polyethylene wax and 3 (parts by weight) stearic acid.
The following table and FIG. 3 show the results of gravimetric measurements of the swelling properties of Example I of the present invention, in which the additive was added, and Comparative Example 2, in which the additive was not added, depending on the water immersion time.

(Test 4) Examples J and K of the present invention in which the 6c ratio of the superabsorbent resin and elastomer was changed as described above.

The following table and FIG. 4 show the results of weighing the expansibility of L, M, and N depending on the water immersion time.

However, in both cases, dioctyl adipate is 10° and liquid paraffin is 30°. 1 part of nutearic acid and 5 parts by weight of polyoxyethylene sorbitan monostearate were added.

As can be seen from the test results described in the embodiments.

) - The water-swellable resin composition of the present invention, which is made by adding a nonionic surfactant such as ethyne oxide and metal thread to a resin composition in which a highly water-absorbent resin is blended with an elastomer, does not impede moldability and is easy to inject. Even when molded using a molding method, a surface coating with excellent affinity for water is created. Therefore, in addition to industrial, agricultural, and construction materials, it is possible to easily provide molded products with shapes suitable for uses such as toys and medical-related products. It is possible to exhibit the characteristics of a super absorbent resin.

[Brief explanation of drawings]

Figures 1, 2, 3, and 4 are graphs of test results showing the relationship between water immersion time and expandability. 'fl(B)me(immersion' I)
] to 1fl (Sun) Me (' し ) responsibility Moe (Sun)

Claims (3)

[Claims] (1) A water-swellable resin composition comprising a highly water-absorbent resin mixed with an elastomer and containing an ethylene oxide condensate-based nonionic surfactant. (2) The blending ratio of the super absorbent resin and the elastomer is 30 nia 0 to 70;
Claims (1) added at a ratio of 5 to 200
) The water-swellable resin composition described in (1). (3) Nonionic surfactant is water-soluble patented edge