JPH09111115A - Water-swellable polymer and water-swellable composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polymer which develops sufficient swellability when brought into contact with water or immersed in water, retains rubbery elasticity even after water swelling and is excellent in the ability to seal a gap in a rigid structure by mixing a specified oligomer with an elastomer. SOLUTION: This water-swellable polymer is formed by mixing a urethane methacrylate oligomer with an elastomer (e.g. chloroprene rubber). The urethane methacrylate oligomer is desirably one prepared by effecting a polyaddition reaction of a mono-, di- or tri-methacrylic acid ester of a monohydric or polyhydric alcohol having one or more OH groups as the side chains (e.g. 2- hydroxypropyl methacrylate) with a urethane prepolymer [e.g. a prepolymer obtained by reacting polyoxyethylene glycol and polyoxytetramethylene glycol with 4,4'-methylenebis(phenyl isocyanate)].

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a water-swelling polymer and composition, and more particularly to a polymer which swells when contacted with water or immersed in water and has an excellent ability to seal a gap in a rigid structure. And a composition.

[0002]

2. Description of the Related Art When constructing a rigid structure such as a concrete structure or a steel frame structure, a fixed gap is provided in advance at a joint portion, and the structure is designed so that expansion or contraction due to external factors or internal factors can be accepted to some extent. To do. Here, the extrinsic factor refers to, for example, a change in environmental temperature due to radiant heat of the sun or seasonal variations, and the intrinsic factor refers to a change in volume due to hardening after concrete is poured.

However, in consideration of the above design, the gap is set with the expected maximum expansion rate as the upper limit, and therefore the gap becomes too large in an average environment or a cold environment. When the gap becomes large in this way, rainwater, river water, seawater, and the like enter the interior through the gap, and as a result, corrosion or the like occurs in the concrete, resulting in destruction of the structure at extreme times.

To solve this problem, a method for solving the problem has been tried for a long time, and at the initial stage, filling of a fiber substance such as Manila hemp, filling of a resin material such as asphalt and pitch, filling of cement mortar, etc. were carried out, Further, with the progress of development of various synthetic resins and rubbers, various materials have been used in various combinations. For example, epoxy resin or polyester resin two-component curable putty and caulking material, and moisture curable urethane or silicone caulking material are still used as effective materials today.

A rubber-like material that retains elasticity is particularly useful in that it can absorb expansion and contraction of the structure to some extent.
However, many of these materials have a problem in that volume shrinkage associated with filling and curing is unavoidable as a characteristic thereof. As an attempt to solve this problem, it has been attempted to give a filler or the like a property of absorbing water and expanding in volume in the presence of rainwater, seawater or the like. As the method, for example, either mixing a hydrophilic substance with a rubber-like substance or imparting hydrophilicity to the molecular structure has been considered, and many proposals have been made.
In the method, a hydrophilic inorganic filler, for example, powder of silica or the like, or organic superabsorbent water such as polyacrylic acid, sodium polyacrylate, starch-acrylic acid graft polymer, carboxylmethylcellulose crosslinked product, polyvinyl alcohol crosslinked product, or the like. Attempts have been made to mix powdery particles of a resin. In addition, in the method, various methods such as (a) introducing a hydrophilic group into rubber, (b) grafting a hydrophilic polymer onto a rubber molecule, and (c) synthesizing a block rubber having a hydrophilic segment can be used. Being tried.

[0006]

Among the above water-swellable compositions, a method of imparting hydrophilicity to a polyurethane resin or a polyurethane rubber, a method of kneading a water-swellable polyurethane resin with a rubber, and the like, Many proposals have been made in recent years regarding materials related to polyurethane.
This is because urethane is easy to introduce a functional functional group such as a hydrophilic group as its reactive property, and various polymer structures can be designed.

However, the urethane-based water-swellable materials proposed so far are disadvantageous in that they are relatively expensive to use alone, and have a problem in compatibility with rubber when they are kneaded with various rubbers. In many cases, it does not form a chemical bond with the rubber molecule, but it is often simply physically dispersed or forming a sea-island structure. After swelling, there were defects such as separation from rubber and desorption or elution.

[0008]

As a result of earnest research in view of the above problems, the present inventors have determined that a predetermined urethane methacrylate oligomer or a macromonomer obtained by living polymerization thereof is one of the essential components. By kneading with an elastomer, which is another essential component, and further crosslinking as necessary, a polymer capable of exhibiting a sufficient water expansion coefficient and exhibiting a water blocking effect while maintaining rubber-like elasticity even after water swelling is obtained. The inventors have found that they can be obtained and completed the present invention.

That is, the present invention is a water-swellable polymer obtained by mixing a urethane methacrylate oligomer and an elastomer. Further, the present invention is a water-swellable polymer obtained by mixing a macromonomer having a number average degree of polymerization of 500 to 20000 obtained by living polymerization of a urethane methacrylate oligomer with an elastomer.

Furthermore, the present invention is a water-swellable polymer obtained by vulcanizing the above polymer. Furthermore, the present invention is a water-swellable composition containing the above-mentioned water-swellable polymer.
Hereinafter, the present invention will be described in detail. In the present invention, the urethane methacrylate oligomer or a macromonomer obtained by living polymerization of the urethane methacrylate oligomer is one of the essential components. Examples of the urethane methacrylate oligomer include those obtained by polyadding a mono-, di-, or trimethacrylic acid ester of a monohydric or polyhydric alcohol having one or more hydroxyl groups in the side chain to a urethane prepolymer. .

By changing the molecular structure of the methacrylic acid ester, the reactivity of the oligomer with the urethane prepolymer and the compatibility and the reactivity with rubber can be changed. Examples of such methacrylic acid esters include 2-hydroxypropyl methacrylate, 2-hydroxy-1,3-dimethacryloxypropane, 3-chloro-2-hydroxypropyl methacrylate, 2-hydroxy-1-acryloxy-3-. Methacryloxypropane, phenylglycidyl ether methacrylate,
Pentaerythritol trimethacrylate, 2-hydroxy-3-phenoxypropyl methacrylate, polyoxyethylene glycol (n = 2) methacrylate, polyoxypropylene (n = 6) monomethacrylate, etc. can be used alone or in combination. . Among them, it is preferable to use 2-hydroxypropyl methacrylate, 2-hydroxy-1,3-dimethacryloxypropane and the like.

As the urethane prepolymer, for example, one obtained by polyaddition reaction of one or more polyalkylene oxide glycol having an alkyl group having 2 to 4 carbon atoms with various diisocyanates can be used. . The polyalkylene oxide glycol is a water-swellable composition or polymer obtained by selecting the molecular weight and type thereof and changing the carbon number of the alkyl group, thereby obtaining the maximum water expansion coefficient without dissolving in water. Can be shown.

Examples of such polyalkylene oxide glycols include polyoxyethylene glycol, polyoxytetramethylene glycol, polyoxypropylene glycol, polyoxyethylene polyoxypropylene alkyl ether, and polyoxyethylene polyoxypropylene glycol copolymer. , Polyoxyethylene glycerin fatty acid ester, polyoxyethylene polyoxypropylene glycol block polymer, ethylene oxide derivative of alkylphenol formalin condensate, and the like, and they can be used alone or in combination. Among them, a combination of polyoxyethylene glycol and polyoxytetramethylene glycol is preferable. The average molecular weight of the polyalkylene oxide glycol is preferably 100 to 50,000, particularly
It is preferably 300 to 3000.

As the diisocyanate, 4,4'-
Methylenebis (phenylisocyanate) (MDI),
Toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), paraphenylene diisocyanate (P
PDI), dicyclohexylmethane diisocyanate (HMDI), isopropylidene bis-4-cyclohexyl diisocyanate (IPC), bitluene diisocyanate (TODI) and the like can be used alone or in combination. Among them, it is preferable to use 4,4′-methylenebis (phenylisocyanate) (MDI), toluene diisocyanate (TDI) and the like.

Urethane methacrylate oligomer produced
Is the residual double bond of the elastomer (various rubbers) described later.
It does not desorb or elute because it crosslinks when combined.
Living polymerization of urethane methacrylate oligomer
The number average degree of polymerization of the obtained macromonomer is 500 to 20,000.
Yes, preferably 1000-5000. Urethane methacrylic
The living polymerization of the rate oligomer is performed by a conventional method.
For example, trimethylaluminum (C
H_Three)_ThreeCombined use of Al and pyridine, or L_i-Arcola
Or Grignard reagent, and L_i ⁺Instead of
S_i ⁺(CH _Three)_ThreeCan be achieved by using
it can.

The macromonomer having such a controlled molecular weight and molecular weight distribution exhibits suitable compatibility with various rubbers due to its methacrylate structure and loses its solubility in water due to the polymerization thereof, resulting in water swellability. Will be shown. In the present invention, a urethane methacrylate oligomer and a macromonomer obtained by living polymerization of the urethane methacrylate oligomer may be used in combination.

The other essential component in the present invention is an elastomer. As the elastomer, natural rubber, synthetic rubber or the like can be used, and as the synthetic rubber, a diene rubber (styrene-butadiene rubber, butadiene rubber, Isoprene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, styrene-isoprene rubber, acrylonitrile-chloroprene rubber, vinyl pyridine-
Butadiene rubber, etc.), olefin rubber (butyl rubber, chlorobutyl rubber, bromobutyl rubber, isobutylene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-vinyl acetate rubber, chlorosulfonated polyethylene, acrylic rubber, etc.), urethane rubber, silicone Examples thereof include rubber, fluororubber and polysulfide rubber. Among these, particularly medium crystallinity chloroprene rubber (WRT), styrene-butadiene rubber, 5-
It is preferable to use ethylidene-2-norbornene-modified ethylene-propylene rubber (EPDM) or the like.

The mixing ratio of the urethane methacrylate oligomer or the macromonomer obtained by living polymerization of the urethane methacrylate and the elastomer is preferably 10: 100 to 50: 100 parts by weight. Urethane methacrylate oligomer or macromonomer obtained by living polymerization
If it is less than 10 parts by weight, the volume expansion coefficient of the resulting water-swellable polymer is 20% or less, which is not practically sufficient, and if it exceeds 50 parts by weight, the mechanical strength of the obtained water-swellable polymer is lowered. In addition, deformation due to water swelling is inevitable.

By kneading the urethane methacrylate oligomer or macromonomer and the elastomer,
The water-swellable polymer of the present invention is obtained. At this time, the oligomer or macromonomer cross-links to some extent with the residual double bond of the rubber, but it may be cross-linked by using a cross-linking agent if necessary. By further crosslinking, the rubber-like elasticity is improved and the mechanical strength is also generally increased,
It will be a product with high toughness.

Examples of such a crosslinking agent include inorganic sulfur, organic sulfur compounds, various peroxides, metal oxides, polyfunctional amines, quinone dioximes, methylol resins, chlorine compounds,
Azo compounds, polyisocyanates, organic metals (silicon)
Examples of the compound include inorganic sulfur, organic sulfur compounds, various peroxides and metal oxides. Further, as other components, additives such as a vulcanizing agent for crosslinking rubber, an oxidation stabilizer, and an antioxidant, and a filler such as carbon and silica can be appropriately added in an appropriate amount. Vulcanizing agents include inorganic sulfur, organic sulfur compounds, sulfur chloride, tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), dipentamethylenethiuram tetrasulfide (DPTT), ethylenethiourea (ETU), 2-mercapto. Benzothiazole (MB
T), dibenzothiazyl disulfide (MBTS), 4,
4'-dithiomorpholine, dicumyl peroxide (DC
P), di-tert-butyl peroxide (TBPH), zinc oxide, magnesium oxide, p-quinone dioxime (QD
M) and the like.

As the oxidation stabilizer, for example, 2,6-di-tert-
Butyl-p-cresol, butylated hydroxyanisole, 2,2-methylene-bis- (4-methyl-6-tert-butylphenol), 1,1,3-tris- (2-methyl-4-hydroxy-5) -t
Examples thereof include phenolic oxidation stabilizers such as ert-butylphenyl) butane, sulfur antioxidants such as dilaurylthiodipropionate, and phosphorus oxidation stabilizers such as triphenylphosphite.

Antiaging agents include poly (2,2,4-trimethyl-1,2-dihydroquinoline), 1- (N-phenylamino) -naphthalene, 2,6-di-tert-butyl-4- Examples thereof include methylphenol and 2,5-di-tert-butylhydroquinone. The water-swellable composition of the present invention can be obtained by kneading the above components, but the composition obtained by kneading may be further vulcanized. Vulcanization may be carried out by a conventional method. For example, when inorganic sulfur is used, a required amount of sulfur powder is added to the composition obtained by kneading, and a vulcanization accelerator is added if necessary. In addition, after further kneading, it can be molded into a sheet or the like, and heated and vulcanized under pressure. By vulcanizing in this way, it is possible to further increase the rubber-like elasticity, acquire a deformation restoring force, and improve a given water-stopping property.

The water-swellable polymers and compositions of the present invention obtained as described above exhibit a sufficient water expansion coefficient and can maintain rubber-like elasticity even after water swelling. Further, the urethane methacrylate oligomer is not likely to be released or eluted from the rubber, and the macromonomer is not likely to be dissolved in water. Furthermore, it also has stable properties that the entire polymer or composition swells uniformly.

Therefore, the water-swellable polymer and composition of the present invention are used for a rigid structure such as a concrete structure or a steel frame structure which is expected to come into contact with or be immersed in water, for example, a shield construction method for a tunnel or the like. Segment joint part of
When water pipe connection parts such as water and sewerage, meshing parts of seawalls in seawall construction, joint parts of bridges, pavement parts, rainwater, river water, seawater, etc. enter the structure, the strength of the structure itself will be reduced, destroyed or damaged. It can be suitably used as a water-proof sealing material or the like at a place where there is a risk of causing obstacles.

[0025]

The polymer and composition of the present invention are considered to be imparted with water swellability by the following mechanism of action. That is, the alkylene oxide group in the polyurethane structure is present on the surface of the polymer or composition, and since the alkylene oxide group exhibits hydrophilicity, the surface of the polymer or composition comes into contact with water or is immersed in water. Then, water is adsorbed on the hydrophilic surface, thereby extending the gap between the polymer chains. Water molecules diffuse inside from this gap and further expand the gap of the polymer chains inside. As a result, the polymer or composition will swell uniformly. The water molecules once permeated and adsorbed inside are retained as equilibrium moisture even after the surface has stopped contacting with water, so that the swollen volume is not sharply reduced without losing the property as a gel.

By such a mechanism of action, the polymer and composition of the present invention can seal the gaps of a rigid structure for a long period of time.

[0027]

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to these examples.

[Example 1] 900 g of polyoxyethylene glycol having an average molecular weight of 1000 and 600 g of polyoxytetramethylene glycol having an average molecular weight of 1000 (molar ratio 60/40)
And were charged into a stainless steel (SUS304) reactor equipped with a paddle type stirring device and a reflux cooling device, and the atmosphere was replaced with nitrogen. Further, 950 g of 4,4′-methylenebis (phenylisocyanate) (MDI) was added to the reactor, and polyaddition reaction was carried out in a nitrogen stream at 50 ° C. and a rotation speed of 200 rpm for 2 hours in the absence of a solvent.

Toluene was added to the obtained urethane prepolymer.
2800 g was added to form a solution, and 460 g of 2-hydroxypropyl methacrylate was added thereto, and the mixture was heated under reflux at 100 ° C. for 12 hours (stirring number: 200 rpm) to cause a polyaddition reaction. After the reaction,
Toluene was removed by heating in vacuum and filtered through a 100-mesh stainless steel (SUS304) wire net to obtain a urethane acrylate oligomer (A).

Then, chloroprene rubber (W with medium crystallinity)
(RT) 100 parts by weight of magnesium oxide (4 parts by weight), zinc oxide (5 parts by weight) and stearic acid (1 part by weight) were added and kneaded on a two-roll mill at room temperature. When these were sufficiently kneaded, 30 parts by weight of the urethane acrylate oligomer (A) was gradually added and kneaded on the roll while continuing the kneading. Finally 2-mercaptoimidazoline (ET
U) 0.5 part by weight was added and further kneaded to obtain a sheet having a thickness of 2 mm.

This sheet was vulcanized at 160 ° C. for 30 minutes and then left to cool to obtain a test piece. As a result of observing the time-dependent change in the volume expansion coefficient of the obtained test piece by immersing it in distilled water, a volume expansion coefficient of 5.5% in one week, 12.0% in two weeks, and 23.5% in one month was confirmed. . The volume expansion coefficient was converted as the cube of the linear expansion coefficient. When the addition amount of urethane acrylate oligomer (A) was changed to 10, 30 and 50 parts by weight relative to 100 parts by weight of chloroprene rubber (WRT), the volume expansion rates after 1 month were 11.3%, 23.5% and 55.0%, respectively. Became. From this result, it has been found that the volume expansion coefficient uniquely increases as the amount of the urethane acrylate oligomer, which is one of the essential components of the present invention, increases. In addition, desorption or elution of the urethane acrylate oligomer from the sheet was not observed.

Example 2 Polyoxyethylene glycol having an average molecular weight of 1450 and polyoxytetramethylene glycol having an average molecular weight of 600 were mixed in a molar ratio of 50/50 and a total weight of 1500 g. To this mixture was added 825 g of toluene diisocyanate (TDI), and the mixture was reacted for 6 hours under the same reaction conditions as in Example 1.

520 g of 2-hydroxypropyl methacrylate was added to the obtained urethane prepolymer, and the mixture was heated at 100 ° C. for 12 hours.
The mixture was heated to reflux (stirring number: 200 rpm) for polyaddition reaction.
Then, the same procedure as in Example 1 was performed to obtain a urethane acrylate oligomer (B). Subsequently, 1 part by weight of zinc stearate and 50 parts by weight of silica were added to 100 parts by weight of styrene-butadiene rubber and kneaded on a two-roll mill at room temperature. When these are sufficiently kneaded, the urethane acrylate oligomer (B) 50
Parts by weight were gradually added on a roll and kneaded. Finally, add 3 parts by weight of tetramethyl thiuram disulfide (TMTD) and 0.5 parts by weight of sulfur, and after further kneading, the thickness is 2 mm.
And the sheet.

This sheet was vulcanized at 160 ° C. for 30 minutes and then left to cool to obtain a test piece. The obtained test piece was immersed in distilled water and the time-dependent change in the volume expansion coefficient was observed.
A volume expansion rate of 0%, 8.4% in 2 weeks, and 18.0% in 1 month was confirmed. In addition, desorption or elution of the urethane acrylate oligomer from the sheet was not observed.

Example 3 800 g of polyoxyethylene glycol having an average molecular weight of 1000 and 1200 g of polyoxytetramethylene glycol having an average molecular weight of 1000 (molar ratio 40/60)
And 4,4'-methylenebis (phenylisocyanate)
(MDI) was reacted with 1270 g for 2 hours under the same conditions as in Example 1 to synthesize a urethane prepolymer.

To this urethane prepolymer, toluene 320
g and 2-hydroxy-1,3-dimethacryloxypropane 46
g was added and the mixture was heated to reflux at 100 ° C. for 12 hours (stirring number: 200 rpm) to cause a polyaddition reaction. After completion of the reaction, heat in vacuum to remove toluene, and use 100 mesh stainless steel (SUS30
4) A urethane acrylate oligomer (C) was obtained by filtering with a wire mesh.

Then, chloroprene rubber (W with medium crystallinity)
(RT) 4 parts by weight of magnesium oxide, 5 parts by weight of zinc oxide, 1 part by weight of stearic acid, 30 parts by weight of silica and 1 part by weight of furnace black were added to 100 parts by weight of RT) and kneaded on a two-roll mill at room temperature. When these were sufficiently kneaded, 30 parts by weight of the urethane acrylate oligomer (C) was gradually added and kneaded on the roll while continuing the kneading. Finally 2-mercaptoimidazoline (ETU) 0.
After adding 5 parts by weight and further kneading, a sheet having a thickness of 2 mm was prepared.

This sheet was vulcanized at 160 ° C. for 30 minutes and then left to cool to obtain a test piece. The obtained test piece was immersed in distilled water and the time-dependent change in the volume expansion coefficient was observed.
A volume expansion rate of 2%, 19.5% in 2 weeks, and 45.0% in 1 month was confirmed. In addition, desorption or elution of the urethane acrylate oligomer from the sheet was not observed.

Example 4 In this example, a macromonomer produced by living polymerization from the urethane acrylate oligomer obtained in Example 1 was used. That is,
100 g of the urethane acrylate oligomer (A) obtained in Example 1 was dissolved in 100 g of dehydrated and dried toluene,
To this was added 5 g of tert-butylmagnesium chloride and 20 g of pyridine, and the reaction was carried out for 48 hours while maintaining the temperature at room temperature (25 ° C.) in a nitrogen stream. The reaction was stopped by adding 50 g of methanol. The number average degree of polymerization of the produced macromonomer was 1200 to 1300.

Subsequently, 30 parts by weight of the urethane acrylate macromonomer was added to 100 parts by weight of 5-ethylidene-2-norbornene-modified ethylene-propylene rubber (EPDM), and 3 g of dicumyl peroxide was further added as a crosslinking agent. Was sufficiently kneaded on two rolls, and then pressure-molded at a pressing pressure of 250 kg / cm ² and a temperature of 120 ° C. to obtain a sheet having a thickness of 2 mm.

The obtained sheet was used as a test piece with a width of 20 mm and a length of 10 mm, and was immersed in distilled water to observe the change over time in the volumetric expansion coefficient. As a result, 4.1% in 1 week, 8% in 2 weeks, and 1 month in 1 month. 1
A volume expansion coefficient of 8% was confirmed.

[0042]

According to the water-swellable composition and the water-swellable polymer of the present invention, a sufficient water swelling rate is exhibited, rubbery elasticity is maintained even after water swelling, and a urethane methacrylate oligomer or a macromonomer is contained. There is no danger of desorption or elution from rubber or dissolution in water.

Claims (7)

[Claims] 1. A water-swellable polymer obtained by mixing a urethane methacrylate oligomer and an elastomer. 2. A water-swellable polymer obtained by vulcanizing the polymer according to claim 1. 3. A water-swellable polymer obtained by mixing a macromonomer having a number average polymerization degree of 500 to 20000 obtained by living polymerization of a urethane methacrylate oligomer with an elastomer. 4. A water-swellable polymer obtained by vulcanizing the polymer according to claim 3. 5. The oligomer obtained by polyadding a mono-, di-, or trimethacrylic acid ester of a monohydric or polyhydric alcohol, which has one or more hydroxyl groups in its side chain, to the urethane prepolymer. The water-swellable polymer according to claim 1 or 3, wherein 6. The urethane prepolymer has 2 carbon atoms.
The water-swellable polymer according to claim 5, which is a urethane prepolymer obtained by polyaddition reaction of one or more kinds of polyalkylene oxide glycol having an alkyl group of 4 to 4 with diisocyanate. 7. A water-swellable composition containing the water-swellable polymer according to claim 1.