JPH038667B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to water-swellable resin compositions that absorb water but are not soluble in water.

(Prior art and its problems) Conventionally, many water-swellable resins have been known to have an anionic group such as a carboxyl group or a sulfonic acid group, or a nonionic group such as a polyoxyethylene group as a hydrophilic group. However, most of them have a crosslinked structure to make them insoluble in water, and as a result, they are insoluble in organic solvents and have no thermoplasticity, so they must be used in powder form and dispersed in a matrix. It didn't happen. As a result, many problems have arisen.

(Means for Solving the Problems) As a result of intensive research to obtain a water-swellable resin that is soluble in organic solvents, thermoplastic, and compatible with a resin matrix, the present inventor has developed a specific block. The present invention was completed after discovering that the structural polyurethane resin solved the drawbacks of the prior art.

That is, the present invention consists of 100 parts by weight of a water-swellable resin and 20 to 2,000 parts by weight of a hydrophobic rubber base material, and the water-swellable resin has at least one of the following structures and has a molecular weight of 3,000 to 60,000 A-B- This is a water-swellable resin composition characterized by being an A-type block copolymer.

A-OCONH-Y-NHCOO-B-OCONH-
Y-NHCOO-A However, A in the formula is a hydrophobic polymer chain with a molecular weight of 1000 to 20000, and B is a hydrophobic polymer chain with a molecular weight of 1000 to 20000.
20,000 polyoxyethylene chains or polyoxyethylene propylene chains containing more than 50% by weight of oxyethylene groups, and Y is the residue of a diisocyanate compound.

To explain the present invention in detail, the present invention uses
The water-swellable resin that mainly characterizes the present invention has at least one A-B-A type structure, that is, a (hydrophobic segment)-(hydrophilic segment)-(hydrophobic segment) bonding format. hand,
These segments are connected by urethane bonds.

The polymer chain forming the hydrophilic segment is a polyoxyethylene chain having a molecular weight of about 1,000 to 20,000 or a polyoxyethylene propylene chain containing 50% by weight or more of oxyethylene units. If the molecular weight of these polymer chains is less than about 1000, the resulting block copolymer will have insufficient water absorption,
On the other hand, when the molecular weight exceeds 20,000, the resulting block copolymer has high water absorption, but becomes easily soluble in water, and the physical strength of the hydrogel formed decreases.

The polymer chain forming the hydrophobic segment has hydroxyl groups at both ends of the molecule, and examples of the polymer chain include polyethylene, polypropylene, polybutylene, ethylene propylene copolymer, polystyrene, polyethylene adipate, polybutylene adipate, and polyethylene butylene adipate. , polyε-caprolactone, polybutylene terephthalate, polyurethane consisting of diol and diisocyanate, etc., which form an aggregated phase in the obtained block copolymer and prevent the block copolymer from dissolving in water when water is absorbed. Such polymer chains preferably have a molecular weight in the range of about 1,000 to 20,000; if the molecular weight is less than about 1,000, the cohesive force of the aggregated phase will be insufficient, and the gel structure of the block copolymer will have insufficient physical strength. On the other hand, when the molecular weight exceeds about 20,000, water absorption becomes insufficient. The weight ratio of the hydrophilic segment to the hydrophobic segment is preferably such that the hydrophilic segment accounts for 50% or more of the total weight.

A urethane bond connects the hydrophilic segment and the hydrophobic segment, and an organic diisocyanate is used for this bond. Such diisocyanates include phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, naphthalene diisocyanate,
Any known diisocyanate can be used, such as toridine diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, bis(isocyanatemethyl)cyclohexane, dicyclohexylmethane diisocyanate, lysine diisocyanate, and trimethylhexamethyl diisocyanate.

The water-swellable resin used in the present invention can be obtained by reacting the above-mentioned reaction components, but the manufacturing method itself may be similar to the conventional manufacturing method of polyurethane resins. A preferred method is to prepare a prepolymer having isocyanate groups at both ends by reacting the hydrophilic segment component with an organic diisocyanate at a reaction equivalent ratio of NCO/OH=about 2, and then reacting the prepolymer with the hydrophobic This is a so-called prepolymer method in which the polymer is reacted with a sex segment component at a reaction equivalent ratio of NCO/OH=approximately 0.5. In the present invention, the preferred molecular weight range of the water-swellable resin is about 3,000 to 60,000;
If the molecular weight is less than 3,000, the water absorption and physical strength of the hydrogel will be insufficient, and if the molecular weight exceeds about 60,000, the solubility in solvents, moldability, etc. will be poor.

Furthermore, a small amount of a reaction component having trifunctional or higher functional groups may be used during the reaction to effect crosslinking to the extent that the solubility in solvents, thermoplasticity, or compatibility with matrices etc. is not lost.

The above reaction may be carried out without a solvent or in an inert solvent. As the solvent, any conventionally known urethane reaction solvent can be used.

In the present invention, water-swellable resins with various performances can be obtained by selecting various proportions of each component and hydrophobic segment components. That is, the water absorbency and physical strength of the hydrogel can also be changed by using components that produce high cohesiveness after polymerization or by using components that produce relatively low cohesiveness. In addition, by selecting a hydrophobic segment with a reactive group such as an unsaturated double bond, the obtained water-swellable resin can be used, molded, or cross-linked after being made compatible with a matrix. It can be combined with the matrix itself.

The water-swellable resin used in the present invention obtained as described above can absorb and retain a large amount of water (for example, about 2 to 40 times its own weight) in water, but due to the cohesive force of the hydrophobic segments, A hydrogel that does not dissolve, is stable, and has high physical strength is obtained. In particular, many conventional water-swellable resins are of anionic type, and their performance such as water absorption is greatly affected by water PH and metal ions. The resin is
Since its hydrophilic segment is nonionic, its performance is not affected much by the pH and dissolved components of the water.

The water-swellable resin composition of the present invention comprises the water-swellable resin described above and a hydrophobic elastic rubber base material as a matrix. Such hydrophobic elastic rubber substrates include natural rubber, polyisoprene, polybutadiene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, polychloroprene, ethylene propylene rubber, acrylic polymer, ethylene-vinyl acetate copolymer, and polyvinyl butyral. Known rubber materials such as resin, silicone rubber, and urethane rubber can be used.

The water-swellable resin used in the present invention is compatible with such a hydrophobic elastic rubber base material, so it can be blended in any proportion, but it depends on the degree of swelling with water and physical strength of the composition, or on the intended use. Therefore, the preferred blending ratio is about 5 to 400 parts by weight per 100 parts by weight of the hydrophobic elastic rubber base material.

The essential components of the water-swellable resin composition of the present invention are as described above, but in addition, plasticizers, process oils, oils, liquid paraffin, vaseline, polyisobutene, various dyes and pigments, various fillers, stabilizers, and blowing agents. , an organic solvent, etc. can be optionally added depending on the purpose.

The components can be easily blended using various kneaders, and since the water-swellable resin and the hydrophobic elastic rubber base material are compatible, it is easy to dissolve them by heating or blend them in a solvent.

(Action/Effect) The water-swellable resin composition of the present invention may be in any form, but representative forms include molded products of various shapes and liquid form. When a molded article (including a molded article that has been solidified from a liquid state) is in water or comes into contact with water, agglomeration of the hydrophobic elastic rubber substrate occurs despite the presence of the hydrophobic elastic rubber substrate, which is a matrix. Despite this, it has the property of absorbing 1.5 to 15 times its own weight in water, expanding its volume accordingly, and returning to its original volume when it dries, no longer coming into contact with water.

Therefore, by filling the voids between the segments of various structures, it exhibits excellent effects as a water-stopping material. In addition to the above-mentioned characteristics of the water-swellable resin itself, the water-swellable resin composition of the present invention is characterized by the fact that the water-swellable resin does not dissolve out of the water-swellable resin composition into water even in water. be. This is because the water-swellable resin used in the present invention has an A-B-A block structure consisting of a hydrophobic segment and a hydrophilic segment, and the hydrophobic segment is tightly aggregated with the matrix. it is conceivable that.

The water-swellable resin composition of the present invention as described above can be used not only as a water-stopping material, but also for modifying the performance of synthetic fibers, plastics, various woven fabrics, etc., sanitary products, water-containing cold insulation materials, soil water-retention materials, and water-retention materials for raising seedlings. It can be advantageously used for materials, humidity control materials, synthetic leather, sweat absorbent materials, dew condensation prevention materials, and other applications.

Next, the present invention will be specifically explained with reference to Examples. Note that "%" or "%" in the text is based on weight. Further, the water swelling degree is a value calculated as follows.

Water swelling degree = weight of sample after water absorption / dry weight of sample Example 1 Polyethylene glycol 100 with average molecular weight 20000
1.8 parts of tolylene diisocyanate and 400 parts of methyl ethyl ketone are charged into a reaction vessel, and then a reaction product of 100 parts of styrene monomer and 25 parts of benzoyl peroxide is hydrolyzed with potassium hydroxide to obtain polystyrene glycol (average molecular weight: 2700). After adding 27 parts and further reacting at 80°C for 16 hours, methyl ethyl ketone was distilled off to obtain 114 parts of a water-swellable resin. The degree of water swelling of this water-swellable resin is
It was 30.5 times bigger.

40 parts of the above water-swellable resin, 100 parts of thermoplastic butadiene-styrene block polymer, 30 parts of clay,
35 parts of process oil and 0.5 parts of zinc stearate
The mixture was kneaded for 6 minutes at 130°C using a Banbury mixer, and then extruded into a shape with a cross section of 30 mm x 5.
A string-shaped water-swellable sealing material of the present invention having an excellent water-stopping effect of 1 mm was obtained.

Example 2 Polyethylene glycol 100 with an average molecular weight of 8300
1 part, 4.3 parts of tolylene diisocyanate, and 400 parts of dioxane were charged into a reaction vessel, and reacted at 80°C for 4 hours. Next, 46 parts of polyethylene adipate with an average molecular weight of about 1900 was added, and after further reaction at 100°C for 15 hours, dioxane was distilled off and the water-swellable resin
Got 140 copies. The degree of water swelling of this water-swellable resin is
It was 18.3 times higher.

A water-swellable sealing material of the present invention having an excellent water-stopping effect was obtained using 60 parts of the above-mentioned water-swellable resin and in the same manner as in Example 1 except for the above water-swellable resin.

Example 3 Polyethylene glycol 100 with an average molecular weight of 20,000
1.8 parts of tolylene diisocyanate and 400 parts of methyl ethyl ketone were placed in a reaction vessel and reacted at 70°C for 1 hour and at 80°C for 3 hours. Next, 20 parts of poly ε-caprolactone with an average molecular weight of 2000 obtained by ring-opening addition polymerization of ε-caprolactone using ethylene glycol as an initiator was added, and after further reaction at 80°C for 16 hours, methyl ethyl ketone was distilled off.
120 parts of water-swellable resin were obtained. The degree of water swelling of this water-swellable resin was 28.3 times.

80 parts of the above water-swellable resin, vinyl chloride elastomer (Deki Kagaku, Denka CS-1060), DOP20
30 parts of clay and 0.5 parts of zinc stearate were kneaded using two rolls at 150°C for 20 minutes to obtain a sheet with a thickness of 3 mm. This sheet was pelletized and extruded using an extrusion molding machine to obtain a string-shaped water-swellable sealing material of the present invention having a cross section of 30 mm x 10 mm and having an excellent water-stopping effect.

Example 4 37 parts of ethylene glycol, 125 parts of 4,4'-diphenylmethane diisocyanate and 0.5 part of dibutyltin laurate were reacted at 80°C for 12 hours under a nitrogen stream to obtain a polyurethane oligomer with an average molecular weight of 1600.

Polyethylene glycol 100 with average molecular weight 8300
1, 4.3 parts of tolylene diisocyanate, and 400 parts of methyl ethyl ketone were placed in a reaction vessel and reacted at 80°C for 4 hours. Then, 39 parts of the above polyurethane oligomer was added, and the mixture was further reacted at 80°C for 16 hours, after which methyl ethyl ketone was distilled off. , water-swellable resin
Obtained 135 copies.

80 parts of the above water-swellable resin, 100 parts of ethylene-vinyl acetate copolymer (vinyl acetate content 40%),
30 parts of clay were kneaded with two rolls to obtain a sheet with a thickness of 3 mm. This sheet was cut to a width of 20 mm to obtain a string-shaped water-swellable sealing material of the present invention having an excellent water-stopping effect.

Test Example A small piece (20 mm x 20 mm x 5 mm) of the water-swellable sealant obtained in Examples 1 to 4 was immersed in distilled water (A) and 3% saline solution (B) for 7 days, and its water swelling was evaluated. When the degree was measured, the results shown in Table 1 below were obtained.

As is clear from the table, the water-swellable sealing material of the present invention has less decrease in water swelling degree in an electrolyte solution, which was a drawback of anionic type water-swellable resins. When used as a sealant for underground concrete segments or as various types of packing, even if a gap occurs and water leaks, the water-swellable resin composition swells, eliminating the gap and providing excellent water-stopping properties. It is effective.

Table 1 Example Water swelling degree of immersion liquid (7 days) 1 A 9.5 B 9.0 2 A 8.1 B 7.9 3 A 4.3 B 4.0 4 A 8.5 B 8.4

Claims (1)

[Claims] 1. 100 parts by weight of water-swellable resin and 20 parts by weight of hydrophobic rubber base material
~2000 parts by weight, and the water-swellable resin has a molecular weight of ~3000 and has at least one of the following structures:
60,000 A-B-A type block copolymer. A-OCONH-Y-NHCOO-B-OCONH-
Y-NHCOO-A (However, A in the formula has a molecular weight of 1000 to 20000
is a hydrophobic polymer chain, and B has a molecular weight of 1000~
20,000 polyoxyethylene chains or polyoxyethylene propylene chains containing 50% by weight or more of oxyethylene groups, and Y is the residue of a diisocyanate compound. )