JPH06287443A - Water-swelling polyurethane composition - Google Patents

Abstract

PURPOSE:To obtain a composition which shows stabilized water-swelling properties for a prolonged period of time and develops prescribed water-swelling properties constantly without deterioration of mechanical strength even after repeated immersion in water. CONSTITUTION:The objective water-polyurethane composition is prepared by forming an interpenetrating polymer network structure from a hydrophilic polyurethane and a water-absorbing polymer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a water-swellable composition obtained by using a hydrophilic polyurethane and a water-absorbing polymer.

[0002]

2. Description of the Related Art Conventionally, as water-swellable compositions, many compositions such as resins and rubbers obtained by mixing a superabsorbent resin with a soft resin or an uncured rubber composition are known. For example, a water-swellable rubber obtained by simply blending a conventional uncured rubber composition with a superabsorbent resin (Japanese Patent Laid-Open No. 64-64-
No. 60683), a water-swellable polyurethane obtained by simply blending an ordinary urethane composition with a superabsorbent resin (JP-A-2-88619), and an ordinary uncured rubber composition modified to give a hydrophilic polymer. A block structure is formed (Japanese Patent Publication No. 3-8667), and a polyurethane in which hydrophilic polyol is partially introduced into a soft segment of polyurethane to impart water absorption (Japanese Patent Publication No.
No. 12492), a water-swellable rubber obtained by simply blending the water-absorbing polyurethane with a normal uncured rubber composition (Japanese Patent Publication No. 63-28107).

[0003]

However, those obtained by simply blending as described in JP-A-64-60683 and JP-A-2-88619 show compatibility of polymers with each other. It is often the case that the dispersion is not uniform because of the difficulty. If the dispersion is not uniform, it is difficult to maintain the initial shape and swell in water. Furthermore, when it is immersed in water for a long period of time, it is difficult to dissolve the water-absorbent resin in water and maintain a stable swelling state. The composition in which the water-absorbent resin is once dissolved does not exhibit swelling property even after being dried and then immersed in water again, and has a drawback in terms of repeated swelling ability.

Further, those using a modified rubber composition as disclosed in Japanese Patent Publication No. 3-8667 and Japanese Patent Laid-Open No.
The hydrophilic polyurethane in which a water-absorbing polymer is introduced as described in JP-A-103661 also has a drawback in that it changes with time, and it is difficult to repeat stable swelling at a target magnification.

Further, a polyurethane composition as described in Japanese Patent Publication No. 2-12492, in which a hydrophilic polyol is partially introduced into a soft segment of polyurethane to impart water absorption, has a high swelling ratio. Therefore, the deformation is large and there is a problem in terms of mechanical strength after swelling,
After swelling, there are some cases where they self-destruct.

Further, most of those obtained by simply blending a water absorbent resin as described in JP-A-58-160386 and JP-B-63-18623 are mostly polyacrylic acid crosslinked products. Since such a polymer electrolyte as described above is used as a water absorbing substance, its swelling ratio tends to be remarkably reduced in a salt solution such as seawater.

The present invention has been made in view of the above problems, and an object thereof is to exhibit stable water swelling performance for a long period of time, and to have a predetermined water content without lowering mechanical strength even when repeatedly immersed in water. It is to provide a composition that exhibits swelling properties.

[0008]

The present invention relates to a water-swellable polyurethane composition in which a hydrophilic polyurethane and a water-absorbing polymer form an interpenetrating polymer network structure (IPN).

[0009]

OPERATION AND EXAMPLES The water-swellable polyurethane composition of the present invention does not simply mix the water-absorbing polymer into the urethane matrix, but allows the cross-linked polyurethane and the cross-linked polymer to penetrate each other without forming a chemical bond. , Has a structure in which polymers are woven together. Therefore, the mechanical strength is high without swelling and collapsing during swelling.

The hydrophilic polyurethane has a function of assisting the swelling property of the hydrophilic polyurethane composition of the present invention and a function of exerting the swelling property in salt solutions such as seawater as well as in the case of fresh water. .

Such a polyurethane can be obtained by reacting an isocyanate component and a polyol component.

As the isocyanate component, tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), crude MDI, xylylene diisocyanate, naphthylene-1,5-diisocyanate, hexamethylene diisocyanate, hydrogenated TDI, hydrogen MDI, isophorone diisocyanate,
Lysine diisocyanate, isopropylidene (4-cyclohexyl) isocyanate, etc. are used. In particular,
MDI and TDI are preferred.

As the polyol component, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polycaprolactone polyol, polycarbonate diol, polybutadiene type polyol,
Acrylic polyol, ethylene oxide propylene oxide copolymer type polyol, epoxy modified polyol, saponified EVA, etc. are used. In particular, polyethylene glycol and ethylene oxide propylene oxide copolymer type polyol are preferable. When a non-hydrophilic component is used, it is used in combination with a hydrophilic component such as polyethylene glycol, polypropylene glycol or polytetramethylene glycol.

Hydrophilic polyurethane is enhanced in hydrophilicity by containing hydrophilic constituent units such as ethylene oxide constituent units, propylene oxide constituent units and tetramethylene oxide constituent units, and as a result, swelling of the water-swellable polyurethane composition. The nature is enhanced. Further, by including such a hydrophilic constitutional unit, the swelling property in a salt solution becomes better.

The molar ratio of polyol to isocyanate is preferably about 2: 1 to 1:10. When the proportion of the polyol is increased, the crosslinking becomes insufficient, a part is eluted, the dimensional stability is deteriorated, and the mechanical cooperation tends to be remarkably reduced. As the proportion of isocyanate increases, the swellability tends to be unsatisfactory.

The water-absorbing polymer forming an IPN with the hydrophilic polyurethane imparts water absorbability to the polyurethane composition and maintains strength when the polyurethane composition swells in water, and particularly suppresses self-destruction. With.

As such a water-absorbing polymer, one or more hydrophilic monomers such as 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, methacrylic acid, acrylic acid, acrylonitrile, acrylamide and sodium acrylate are polymerized. You can get what you get. In addition, copolymerizable monomers such as vinyl acetate, methyl methacrylate, methyl acrylate may be copolymerized up to about 50% by weight to impart the properties of the monomer.

The structure of the water-swellable polyurethane composition of the present invention is shown in FIG. The composition of the present invention, as shown in FIG.
The crosslinked hydrophilic polyurethane and the crosslinked water-absorbing polymer penetrate each other to form an IPN. The weight ratio of the hydrophilic polyurethane and the water-absorbent polymer is 95: 5-3.
0:70, particularly 90:10 to 60:40 are preferable. When the proportion of hydrophilic polyurethane is increased, mechanical strength is significantly reduced during swelling and self-destruction is more likely to occur, and when the proportion of water-absorbing polymer is increased, sufficient swelling tends to be difficult to achieve in salt solutions such as seawater. There is.

By combining the hydrophilic polyurethane and the water-absorbing polymer in this way, stable swelling behavior is exhibited for a long period of time without elution in water and salt water, and even when repeatedly immersed in water. It is possible to obtain the effect of exhibiting a predetermined swelling property without lowering the mechanical strength. When a hydrophilic alkylene oxide repeating unit is introduced into the crosslinked polyurethane chain,
Regarding the water absorption, it is not only given by the crosslinked water-absorbing polymer, but also by the alkylene oxide repeating unit. The crosslinked water-absorbing polymer also serves to suppress the mechanical strength after swelling and the self-destruction phenomenon.

The water-swellable polyurethane composition of the present invention comprises
For example, it is manufactured as follows.

First, 20 parts of polyol and isocyanate are added.
A urethane polymer is obtained by reacting at a temperature of ~ 90 ° C.
A hydrophilic polyurethane is obtained by adding a curing agent to the obtained urethane polymer, stirring, casting in a mold and leaving it to stand. This hydrophilic polyurethane is immersed in an acrylic monomer solution containing a radical polymerization initiator and a crosslinking agent to shield it from light. By allowing this to stand, the solution is uniformly absorbed in the hydrophilic polyurethane. The water-swellable polyurethane composition is obtained by radically polymerizing the swollen polyurethane at 30 to 130 ° C. under vacuum.

In the above-mentioned production method, the temperature of immersion of the hydrophilic polyurethane in the acrylic monomer solution is preferably around room temperature when using a normal radical polymerization initiator (medium temperature initiator), and at most about 40 ° C. When the radical polymerization initiator of the type is used, the temperature during the immersion can be further increased. Forming an IPN using a hydrophilic polyurethane swollen by adding a solvent such as toluene or benzene to a urethane prepolymer has an advantage that the acrylic monomer solution is likely to be uniformly impregnated in the hydrophilic polyurethane in a short time.

The composition of the present invention is effectively used in the field of optical materials such as lenses and sensors, medical fields such as contact lenses, artificial blood vessels and artificial organs, and the field of biocompatible materials, and is used as a waterproof material. You can also

Next, the present invention will be described with reference to specific examples, but the scope of the present invention is not limited thereto.

Example 1 86.8 parts by weight of polyethylene glycol (hydroxyl number 32.9) having an average molecular weight of 3300 and 13.2 parts by weight of paradiphenylmethane diisocyanate (MDI) were mixed at 70 ° C. for 3 days.
The reaction was carried out for a time to obtain a urethane polymer having an NCO content of 3.3% by weight. Trimethylolpropane (TMP) as a curing agent was added to 100 parts by weight of the obtained urethane polymer.
After adding 5 parts by weight and stirring for 120 seconds, the mixture was cast into a mold at room temperature. After standing for 24 hours, the mold was removed to obtain a white hydrophilic polyurethane.

100 parts by weight of the obtained hydrophilic polyurethane was added to ethylene glycol dimethacrylate (EGDM).
A) 4.6 × 10 ⁻³ parts by weight of radical polymerization initiator 2,
2'-azobisisobutyronitrile (AIBN) 4.4
X10 ⁻³ parts by weight was dissolved in 40 parts by weight of 2-hydroxyethyl methacrylate (HEMA) to freeze−
It was immersed in a solution degassed by the thaw method and shielded from light. The hydrophilic polyurethane completely absorbed the solution and swelled in about 1 hour, but it was allowed to stand at room temperature for 24 hours under light shielding until the solution was uniformly absorbed in the hydrophilic polyurethane. This swollen polyurethane is placed under vacuum (2 mmHg) at 60 ° C. for 24 hours.
When the radical polymerization was carried out for a period of time, a colorless transparent resin, that is, the water-swellable polyurethane composition of the present invention was obtained. The structure of this composition is schematically shown in FIG.

Example 2 37.3 parts by weight of polyethylene glycol used in Example 1 and polyethylene oxide / polypropylene oxide copolymer type polyol having an average molecular weight of 2400 (polyethylene oxide 30% by weight, hydroxyl value 45.5) 47.5 parts by weight. 15.2 parts by weight of MDI was added to the mixture with 1 part and reacted at 70 ° C. for 3 hours to obtain a urethane prepolymer having an NCO content of 2.6%.

2.8 parts by weight of TMP as a curing agent was added to 100 parts by weight of the obtained urethane prepolymer, stirred for 120 seconds, and then poured into a mold at room temperature. After standing for 24 hours, the mold was removed to obtain a white hydrophilic polyurethane.

100 parts by weight of the obtained hydrophilic polyurethane was added to N, N'-methylenebisacrylamide (MBA).
A) 4.6 × 10 ⁻³ parts by weight and water-soluble radical polymerization initiator 2,2′-azobis (2-amidinopropane) dihydrochloride (V-50: manufactured by Wako Pure Chemical Industries, Ltd.)
4.4 × 10 ⁻³ parts by weight was dissolved in 40 parts by weight of HEMA and immersed in a solution degassed by the freeze-thaw method to shield from light. The hydrophilic polyurethane completely absorbed the solution and swelled in about 2 hours, but it was allowed to stand at 5 ° C. for 36 hours under light shielding until the solution was uniformly absorbed in the hydrophilic polyurethane. Vacuum this swollen polyurethane (2 mmH
g) Under radical polymerization at 60 ° C. for 24 hours, a colorless transparent resin, that is, the water-swellable polyurethane composition of the present invention was obtained. Example 3 20 parts by weight of MDI in a mixture of 33.6 parts by weight of polyethylene glycol having an average molecular weight of 1450 (hydroxyl value 80.0) and 46.4 parts by weight of the polyethylene oxide / polypropylene oxide copolymer type polyol used in Example 2. Was added and reacted at 70 ° C for 3 hours to give an NCO content of 3.3%.
I got the urethane polymer.

2. A curing agent prepared by adding 50 parts by weight of dehydrated and purified toluene to 100 parts by weight of the obtained urethane prepolymer, and further mixing 1.4-butanediol (1.4BD) / TMP at a molar ratio of 97/3. 70 by adding 5 parts by weight
A polyurethane swollen with toluene was obtained by reacting at 24 ° C. for 24 hours and then at 110 ° C. for 24 hours. After cooling to room temperature, 100 parts by weight of polyurethanes Gill (parts that do not contain toluene), EGDMA4.6 × ^{10 -3} parts by weight AIBN4.4 × ^{10 -3} parts by weight 40 parts by weight of the HE
A solution that was dissolved in MA and degassed by the freeze-thaw method was added to shield from light. The polyurethane swollen with toluene absorbed all the solution in about 3.5 hours and swollen, but it was allowed to stand at 5 ° C. for 48 hours under light shielding until the solution was uniformly absorbed in the polyurethane.

When this swollen polyurethane was radical-polymerized at 60 ° C. for 24 hours in a nitrogen atmosphere, a colorless transparent toluene swollen resin was obtained. This is decompressed (2mmHg)
When dried below at 100 ° C. for 7 hours, a slightly yellowish transparent resin containing bubbles, that is, the water-swellable polyurethane composition of the present invention was obtained.

Experimental Example For the samples obtained in Examples 1 to 3, the swelling ratio of ion-exchanged water, the swelling ratio of 2% saline solution, the tensile strength after repeated swelling and drying, and the immersion in hot water at 70 ° C. were carried out by the method described below. The amount of later extract was measured. Furthermore, the presence or absence of deformation, separation, and peeling was examined by visually observing the sample after swelling.

Swelling ratio of ion-exchanged water and 2% saline A test piece of 20 mm × 20 mm × 20 mm was cut out from each sample, and they were cut with ion-exchanged water at 20 ° C. and 2%.
The sample was dipped in the saline solution and the volume after 24 hours was measured to calculate the swelling ratio. Further, these samples were immersed in ion-exchanged water at 20 ° C. until reaching swelling parallel, and the time until reaching swelling stability and the volume at that time were measured to calculate the swelling ratio. The swelling ratio was calculated by the following formula.

Swelling ratio (%) = (volume after swelling / volume before swelling) × 100 Tensile strength after repeated swelling and drying Tensile test pieces were punched out from each sample with JIS No. 3 dumbbells and pulled by an Instron tensile tester. The test was conducted. This result was designated as A. A test piece was obtained by the same method, immersed in ion-exchanged water at 20 ° C. for 7 days, dried in a vacuum dryer at 70 ° C. for 12 hours, and similarly subjected to a tensile test. This result was designated as B. B
The sample after swelling and drying according to (1) was immersed in ion-exchanged water for another 7 days, dried in the same manner, and similarly subjected to a tensile test. This result was designated as C. The sample after swelling and drying according to C was immersed in ion-exchanged water for another 7 days, dried in the same manner, and similarly subjected to a tensile test. This result was designated as D. Extract amount A 40 mm x 40 mm x 2 mm test piece was cut out from each sample, and each test piece was immersed in distilled water at 70 ° C for 3 days, after which the immersion water was recovered and most of the water was distilled off with a rotary evaporator. The mass of the extract was measured by performing drying to a constant weight in a vacuum dryer at 60 ° C. The extraction rate was calculated by the following formula.

Extraction rate (%) = (mass of extract / mass of test piece before soaking) × 100 Appearance after swelling Deformation, separation, peeling, cracking, etc. after swelling of each sample subjected to ion exchange water swelling test It was judged by visual observation whether or not the phenomenon occurred.

The results of each test are shown in Table 1.

[0037]

[Table 1]

[0038]

INDUSTRIAL APPLICABILITY The water-swellable polyurethane composition of the present invention, in which hydrophilic polyurethane and water-absorbing polymer form IPN, the constituent polymers are not separated and extracted, and the initial shape is maintained in water. It is an excellent composition that shows stable water swelling property for a long period of time as it is, and does not lose strength even after repeated dry swelling. Further, the composition of the present invention exhibits the same swelling property as that of fresh water in a salt solution, so that it can be used in seawater.

Further, in the normal state, the water-absorbing polymer hardly elutes and has a high transparency unlike the simple blended product. Therefore, the field of optical materials such as lenses and sensors, contact lenses, artificial blood vessels and It is effectively used in the medical field such as artificial organs and the biocompatible material field.

Further, the composition of the present invention can be applied to a segment sealing material for a shield construction method, a fume tube, a box culvert, a water blocking material for a joint, a packing, a gasket and the like.

[Brief description of drawings]

FIG. 1 IPN of a water-swellable polyurethane composition of the present invention
It is a schematic diagram which shows a structure.

Claims (3)

[Claims] 1. A water-swellable polyurethane composition in which a hydrophilic polyurethane and a water-absorbing polymer form an interpenetrating polymer network structure. 2. The water-swellable polyurethane composition according to claim 1, wherein the polyurethane has at least one constitutional unit selected from ethylene oxide constitutional units, propylene oxide constitutional units, and tetramethylene oxide constitutional units. 3. The water-swellable polyurethane composition according to claim 1, wherein the water-absorbent polymer is a polymer obtained by polymerization of hydroxyethyl methacrylate or copolymerization of hydroxyethyl methacrylate with another acrylic monomer.