JP5331971B2 - Polymer gel bonding method - Google Patents

Description

  The present invention relates to a polymer gel joining method.

  Polymer gel is a three-dimensional cross-linked organic polymer that contains water or an organic solvent and swells. As a soft material with swelling and rubbery elasticity, it can be used for medical / medicine, food, civil engineering, bioengineering, sports. Widely used in related fields (for example, see Non-Patent Document 1).

  When actually using such a polymer gel material, it is necessary to process it into a complicated shape according to the purpose, as with other metal materials and organic polymer materials. It was strongly desired to be able to do it. Welding technology is an effective joining method used in many metal materials and some organic polymer materials (eg, polyvinyl chloride), and it is extremely effective if polymer gels can be processed by the same method. It was estimated that it was possible to perform proper molding. However, a method for joining polymer gels has not been known so far.

  In addition, a polymer polymer of water-swellable clay mineral and organic polymer that forms a three-dimensional network by combining water-soluble organic monomer polymer and water-swellable clay mineral peeled in layers is known. (Patent Document 1). However, Patent Document 1 does not disclose a method for joining polymer gels.

JP 2002-53629 A

"Gel Handbook" p226-727, Yoshihito Nagata, Satoshi Sugawara: NTN Corporation, 1997

  The problem to be solved by the present invention is to provide a simple and effective method for joining polymer gels.

  As a result of diligent research to solve the above problems, the present inventors use a polymer gel having a three-dimensional network composed of a polymer obtained from a water-soluble organic monomer and a water-swellable clay mineral, and The inventors have found that by using the cut surface, the polymer gel can be effectively bonded, and the present invention has been completed.

  That is, the present invention is a method for joining a polymer gel having a three-dimensional network structure formed of a polymer (A) of a water-soluble radically polymerizable organic monomer and a water-swellable clay mineral (B). Forming a cut surface on both surfaces of one or both surfaces of the polymer gel to be bonded, and bonding the polymer gel by bonding the cut surfaces or the cut surface and the non-cut surface together A feature of the present invention is to provide a polymer gel bonding method.

  By using the polymer gel bonding method of the present invention, the polymer gel can be processed into a desired shape, and can be formed into a complex shape without using an expensive metal mold. In addition, a polymer gel excellent in swelling property and functionality can be easily prepared. Such polymer gel can be applied to various uses, in particular, medical materials, medical instrument materials, regenerative medical materials, health maintenance / sports equipment materials, beauty materials, analytical instrument materials, industrial materials, agricultural materials, architectural civil engineering materials, etc. Useful for.

  In this specification, the polymer (A) of the above water-soluble radical polymerizable organic monomer is hereinafter referred to as a water-soluble organic monomer polymer (A), and the water-soluble organic monomer polymer (A) and water swellability are described below. A polymer gel having a three-dimensional network composed of clay mineral (B) is referred to as an organic polymer / clay composite polymer gel.

  The polymer gel bonding method in the present invention uses an organic polymer / clay composite polymer gel having a three-dimensional network composed of a water-soluble organic monomer polymer (A) and a water-swellable clay mineral (B), and the cutting thereof. It is based on joining polymer gels using surfaces.

  The organic polymer / clay composite polymer gel used in the present invention is equivalent to that obtained by the method described in Patent Document 1. More specifically, a water-swellable organic monomer polymer and a water-swellable clay mineral separated in a layer form are combined at a molecular level to form a three-dimensional network. However, the bond between the water-soluble organic polymer polymer and the water-swellable clay mineral needs to be mainly due to any one of hydrogen bond, ionic bond, and coordination bond. Those containing a very small amount of covalent bond can be used, but as the amount of covalent bond introduced increases, the polymer gel cannot be joined rapidly as shown in the comparative example.

  As the water-soluble organic monomer in the present invention, those having a property of being dissolved in water and having an interaction with a water-swellable clay mineral that can be uniformly dispersed in water are preferable, for example, clay mineral and hydrogen bond, ionic bond, Those having a functional group capable of forming a coordination bond, a covalent bond and the like are preferable. Specific examples of water-soluble organic monomers having these functional groups include water-soluble polymerizable unsaturated groups having amide groups, amino groups, ester groups, hydroxyl groups, tetramethylammonium groups, silanol groups, epoxy groups, and the like. Examples thereof include organic monomers. Among them, a polymerizable unsaturated group-containing water-soluble organic monomer having an amide group or an ester group is preferable. The water referred to in the present invention includes a mixture of water and an organic solvent miscible with water in addition to water alone.

  Specific examples of the polymerizable unsaturated group-containing water-soluble organic monomer having an amide group include acrylamides such as N-alkylacrylamide, N, N-dialkylacrylamide, and acrylamide, or N-alkylmethacrylamide, N, N- And methacrylamides such as dialkylmethacrylamide and methacrylamide. Here, an alkyl group having 1 to 4 carbon atoms is particularly preferably selected. Specific examples of the polymerizable unsaturated group-containing water-soluble organic monomer having an ester group include methoxyethyl acrylate, ethoxyethyl acrylate, methoxyethyl methacrylate, and ethoxyethyl methacrylate.

  Examples of the water-soluble organic monomer polymer include poly (N-methylacrylamide), poly (N-ethylacrylamide), poly (N-cyclopropylacrylamide), poly (N-isopropylacrylamide), and poly (acryloylmorpholine. ), Poly (methacrylamide), poly (N-methylmethacrylamide), poly (N-cyclopropylmethacrylamide), poly (N-isopropylmethacrylamide), poly (N, N-dimethylacrylamide), poly (N, N-dimethylaminopropylacrylamide), poly (N-methyl-N-ethylacrylamide), poly (N-methyl-N-isopropylacrylamide), poly (N-methyl-Nn-propylacrylamide), poly (N, N-diethylacrylamide), poly N-acryloylpyrrolidin), poly (N-acryloylpiperidine), poly (N-acryloylmethylhomopiperazine), poly (N-acryloylmethylpiperazine), poly (acrylamide), poly (methoxyethyl acrylate), Examples include poly (ethoxyethyl acrylate), poly (methoxyethyl methacrylate), and poly (ethoxyethyl methacrylate). Among these, poly (N, N-dimethylacrylamide) exhibits a particularly excellent bonding effect in the bonding method of the present invention. The water-soluble organic monomer polymer may be a polymer from a single polymerizable unsaturated group-containing water-soluble organic monomer as described above, or a plurality of different polymerizable unsaturated group-containing water-soluble organic materials selected from these. It is also effective to use a copolymer obtained by polymerizing monomers. A copolymer of the above water-soluble organic monomer and other organic solvent-soluble polymerizable unsaturated group-containing organic monomer can also be used as long as the integrated polymer gel according to the present invention can be achieved. .

  The water-soluble organic monomer polymer (A) in the present invention is obtained by polymerizing the water-soluble organic monomer, and has water-solubility or hydrophilicity (or amphiphilicity) having a property of absorbing water. Furthermore, those having functionality such as response to heat, pH and light, and biocompatibility including bioabsorbability and biodegradability are more preferably used depending on the application. For example, water-soluble organic monomer polymers that have characteristics that polymer properties in aqueous solution (for example, hydrophilicity and hydrophobicity) change greatly with slight temperature changes before and after the lower critical solution temperature (LCST) Specific examples thereof include poly (N-isopropylacrylamide) and poly (N, N-diethylacrylamide). Examples of biocompatibility include poly (methoxyethyl acrylate) and poly (methacrylamide).

  As the clay mineral (B) used for the organic polymer / clay composite polymer gel in the present invention, those having a swelling property in water, preferably those having a property of swelling between layers by water are used. More preferably, it is a layered clay mineral that can be at least partially exfoliated and dispersed in layers in water, and particularly preferably a lamellar clay mineral that can be exfoliated and dispersed uniformly in water with a thickness of 1 to 10 layers. For example, water-swellable smectite or water-swellable mica is used. More specifically, water-swellable hectorite containing sodium as an interlayer ion, water-swellable montmorillonite, water-swellable saponite, water-swellable synthetic mica, etc. Is mentioned.

  In the present invention, the mass ratio (B / A) of the water-swellable clay mineral (B) to the water-soluble organic monomer polymer (A) is preferably 0.01 to 1.0, more preferably 0.00. 05 to 0.7, particularly preferably 0.1 to 0.5. If it is this range, sufficient joint surface strength of the polymer gel can be obtained.

  In the present invention, it is preferable to apply the water-soluble organic polymer (C) to the surfaces to be bonded before bonding to increase the bonding strength. The water-soluble organic polymer (C) to be used is an organic molecule or an organic polymer that can be dissolved or mixed in water, and particularly those that can interact with the water-swellable clay mineral (B). Specifically, it is a water-soluble organic polymer having a hydrophilic functional group such as an ether group, a hydroxyl group, a carboxyl group, an amide group, and an amino group. Examples thereof include polyethylene glycol, polypropylene glycol, polyvinyl alcohol, polyvinyl pyrrolidone, (Hydroxyethyl acrylate), poly (hydroxyethyl methacrylate), poly (N-methylacrylamide), poly (N-ethylacrylamide), poly (N-cyclopropylacrylamide), poly (N-isopropylacrylamide), poly (acryloyl morpholine) Phosphorus), poly (methacrylamide), poly (N-methylmethacrylamide), poly (N-cyclopropylmethacrylamide), poly (N-isopropylmethacrylamide), poly (N, N-dimethylacrylamide) , Poly (N, N-dimethylaminopropylacrylamide), poly (N-methyl-N-ethylacrylamide), poly (N-methyl-N-isopropylacrylamide), poly (N-methyl-Nn-propylacrylamide) , Poly (N, N-diethylacrylamide), poly (N-acryloylpyrrolidine), poly (N-acryloylpiperidine), poly (N-acryloylmethylhomopiperadine), poly (N-acryloylmethylpiperazine) , Poly (acrylamide), polyacrylic acid, hyaluronic acid, polyethyleneimine, polypropyleneimine, agarose, alginic acid, carrageenan, collagen, methylcellulose, carboxymethylcellulose, hydroxypropylcellulose, cellulose derivatives, chitansan gum , Gellan gum, chitosan and the like. These may be used alone or in combination. In use, the water-soluble organic polymer is dissolved in water or a solvent in advance and applied to the surfaces to be joined.

  In the bonding method of the present invention, an organic polymer / clay composite polymer gel having a three-dimensional network composed of a water-soluble organic monomer polymer and a water-swellable clay mineral is cut, and the resulting cut surface is used to cut the organic polymer / clay composite polymer gel. It is to join a polymer / clay composite polymer gel. Specifically, the case where the cut surfaces are bonded to each other and the case where the cut surfaces and the non-cut surface are bonded to each other are included. When non-cut surfaces are used, sufficient bonding cannot be obtained even if they are bonded together. A known method is used for the cutting method and is not particularly limited.

  In the present invention, after bonding the surfaces to be bonded, the bonding of the bonded surfaces is promoted and strengthened by performing any one or more of heating, pressurization, and ultrasonic irradiation. Can do. The heating is performed between 20 ° C. and 100 ° C., and the appropriate temperature varies depending on the composition of the organic polymer / clay composite polymer gel, more preferably from 30 ° C. to 90 ° C., particularly preferably from 40 ° C. to 80 ° C. In general, the higher the temperature, the faster the bonding is promoted. The bonding of the polymer gel is also promoted by pressurization. The pressure of the pressurization is not particularly limited as long as the organic polymer / clay composite polymer gel does not undergo composition deformation and varies depending on the composition and other joining conditions. In general, the higher the pressure applied, the higher the bonding effect. Furthermore, bonding is also promoted by ultrasonic irradiation. The irradiation time and intensity vary depending on the composition of the organic polymer / clay composite polymer gel and other joining conditions, and are selected within the range of known apparatus conditions. Furthermore, if the water-soluble organic polymer (C) is applied before these treatments, the bonding effect may be further enhanced.

  The reason why the polymer gel can be joined by a simple method of bonding them using the cut surfaces of the organic polymer / clay composite polymer gel is not necessarily clear, but is estimated as follows. On the cut surface (surface) of the organic polymer / clay composite polymer gel, a number of dangling chains that are bonded to the clay at one end and free at the other end are formed. By bonding the cut surface with the other organic polymer / clay composite polymer gel surface, the free end of these dangling chains is bonded to the clay in the vicinity of the other gel surface, thereby bonding the bonded surface. It is thought to occur. This means that in organic polymer / clay composite polymer gels, the chain length of the polymer bonding between adjacent clays is long (thus, the dangling chains that are generated when they are cut in half on average are long) ), And the polymer / clay bond is a non-covalent bond such as a hydrogen bond. In fact, as shown in Comparative Examples 1 and 2, bonding by bonding does not occur in a chemically crosslinked gel that does not produce long dangling chains (because of the short molecular weight between crosslinking points) even when cut. In addition, when the ratio of clay / organic polymer is high even in the organic polymer / clay composite polymer gel (example: 2.0 (Comparative Example 3)), the dangling chain is similarly short, so that the effective bonding strength is not obtained. In addition, since the number of dangling chains is greater when the cut surfaces are bonded together, generally stronger bonding is possible, and the treatment of heating, pressurization, ultrasonic irradiation, etc. requires a free end of the dangling chain. It is estimated to be effective in promoting bonding because it increases the chance of binding to the opponent's clay.

  EXAMPLES Next, although an Example demonstrates this invention more concretely, this invention is not limited only to the Example shown below from the first.

(Examples 1 and 2)
For the water-swellable clay mineral, water-swellable synthetic hectorite (trademark Laponite XLG) having a composition of [Mg _5.34 Li _0.66 Si ₈ O ₂₀ (OH) ₄ ] Na ⁺ _0.66 is dissolved in water. N, N-dimethylacrylamide (DMAA: manufactured by Kojin Co., Ltd.) was used as the organic monomer. DMAA was used after removing the polymerization inhibitor by purification.

  As the polymerization initiator, potassium peroxodisulfate (KPS: manufactured by Kanto Chemical Co., Inc.) was used as an aqueous solution at a ratio of KPS / water = 0.40 / 20 (g / g). As the catalyst, N, N, N ′, N′-tetramethylethylenediamine (TEMED: manufactured by Wako Pure Chemical Industries, Ltd.) was used.

In a thermostatic chamber at 20 ° C., 38.04 g of pure water and 1.829 g of Laponite XLG were added to a flat bottom glass container to prepare a colorless and transparent solution. To this was added 3.96 g of DMAA to obtain a colorless transparent solution. Next, 2.0 g of KPS aqueous solution and 32 μl of TEMED were added with stirring, this solution was transferred to a sealed container of 1 cm × 1 cm × 6 cm, and then left to stand in a constant temperature water bath at 20 ° C. for polymerization for 20 hours. All operations from preparation of the solution to polymerization were performed in a nitrogen atmosphere in which oxygen was blocked. After 20 hours from the start of polymerization, a colorless transparent and uniform organic polymer (PDMAA) / clay composite polymer gel composed of an organic monomer polymer and a layered exfoliated clay mineral was formed in the container (clay / organic polymer = 0.46). ). The obtained organic polymer / clay composite polymer was divided into two equal parts with a thickness of 0.5 cm to obtain two polymer gels of 0.5 cm × 1 cm × 6 cm. In (Example 1), the polymer gel was bonded so that the cut surfaces overlap each other by 0.5 cm, and in (Example 2), the cut surface and the non-cut surface were overlapped by 0.5 cm each. In addition, a load of 45 g per 1 cm ² was applied to the overlapped portion and held in a sealed container for 10 hours. As a result, it was visually confirmed that the bonded portions were uniformly and firmly joined. Using the tensile test device (manufactured by Shimadzu Corporation, desktop universal testing machine AGS-H), the distance between the scores = 20 mm, the pulling speed = 100 mm / min, so that the obtained joint portion is at the center. I went there. As a result, in Example 1, strength = 80 kPa and breaking elongation = 900% were obtained, and in Example 2, strength = 50 kPa and breaking elongation = 500% were obtained. In addition, the tensile test of the polymer gel which does not have the cut surface joint part synthesized similarly was strength = 100 kPa and breaking elongation = 1050%.

(Example 3)
For the water-swellable clay mineral, water-swellable synthetic hectorite (trademark Laponite XLG) having a composition of [Mg _5.34 Li _0.66 Si ₈ O ₂₀ (OH) ₄ ] Na ⁺ _0.66 is dissolved in water. N-isopropylacrylamide (NIPA: manufactured by Kojin Co., Ltd.) was used as the organic monomer. NIPA was used after removing the polymerization inhibitor by purification.

  As the polymerization initiator, potassium peroxodisulfate (KPS: manufactured by Kanto Chemical Co., Inc.) was used as an aqueous solution at a ratio of KPS / water = 0.40 / 20 (g / g). As the catalyst, N, N, N ′, N′-tetramethylethylenediamine (TEMED: manufactured by Wako Pure Chemical Industries, Ltd.) was used.

In a constant temperature room at 20 ° C., 38.04 g of pure water and 0.61 g of Laponite XLG were added to a flat bottom glass container to prepare a colorless and transparent solution. To this, 4.52 g of NIPA was added to obtain a colorless transparent solution. Next, 2.0 g of KPS aqueous solution and 32 μl of TEMED were added with stirring, and this solution was transferred to a sealed container of 1 cm × 1 cm × 6 cm, and then left to stand in a constant temperature water bath at 20 ° C. for 20 hours for polymerization. went. All operations from preparation of the solution to polymerization were performed in a nitrogen atmosphere in which oxygen was blocked. After 20 hours from the start of polymerization, a colorless transparent and uniform organic polymer (PNIPA) / clay composite polymer gel composed of an organic monomer polymer and layered exfoliated clay mineral was produced in the container (clay / organic polymer = 0.135). ). The obtained organic polymer / clay composite polymer gel was divided into two equal parts with a thickness of 0.5 cm to obtain two polymer gels of 0.5 cm × 1 cm × 6 cm. The cut surfaces of the polymer gel were bonded so as to overlap each other by 0.5 cm, and a load of 45 g per 1 cm ² was applied to the overlapped portion and held in a sealed container for 10 hours. As a result, it was visually confirmed that the bonded portions were uniformly and firmly joined. A tensile test was conducted in the same manner as in Example 1 so that the obtained joined portion was at the center. As a result, strength = 30 kPa and elongation at break = 1100% were obtained. In addition, the tensile test of the polymer gel which does not have the cut surface joint part synthesized similarly was strength = 40 kPa and breaking elongation = 1200%.

(Examples 4 and 5)
An organic polymer (PDMAA) / clay composite polymer gel synthesized in the same manner as in Example 1 except that 1.22 g of Laponite XLG was used (clay / organic polymer = 0.31) was used. The gel was cut in the middle to form a gel. What was bonded together by hand so that the cut surfaces of the two cut gels were in close contact with each other was put in a sealed glass container. Hold for a minute. Thereafter, the polymer gel taken out from the glass container was uniformly bonded to such an extent that the cut surface was not visually understood. A tensile test was performed in the same manner as in Example 1 except that the distance between chucks was set to 30 mm so that the joint surface was at the center. As a result, (Example 4) obtained strength = 100 kPa and breaking elongation = 1550%, and (Example 5) obtained strength = 102 kPa and breaking elongation = 1540%. In any case, the fracture in the tensile test occurred in the chuck portion. In addition, the tensile test of the polymer gel which does not have the cut surface joint part synthesize | combined similarly was intensity | strength = 101 kPa and breaking elongation = 1530%.

(Examples 6, 7, and 8)
4. Use 3.5 g (Example 6) or 0.10 g (Example 7) or 4.5 g (Example 8) of Laponite XLG and 3.96 g (Example 6 and Example 8) or 5. An organic polymer (PDMAA) / clay composite polymer gel was obtained in the same manner as in Example 4 except that 94 g (Example 7) was used. The clay / organic polymer is 0.88 in Example 6, 0.0168 in Example 7, and 1.29 in Example 8. In the same manner as in Example 4, a cut surface was prepared, and a tensile test was performed on a polymer gel including a bonded surface obtained by bonding. As a result, in each case, it was observed that the bonded surfaces were visually joined. The measured breaking strengths were 35% (Example 6), 98% (Example 7) and 11% (Example 8) of the same gel having no joint surface.

Example 9
An organic polymer / clay composite polymer gel having a cut surface bonded thereto was obtained in the same manner as in Example 4 except that ultrasonic irradiation was performed for 30 minutes instead of heating. In a tensile test performed in the same manner as in Example 4, strength = 85 kPa and elongation at break = 1310% were obtained.

(Examples 10 and 11)
Before bonding, apply a poly (N, N-dimethylacrylamide) aqueous solution (concentration: 4% by mass) to the cut surface (Example 10), and apply a polyvinyl alcohol aqueous solution (concentration: 4% by mass). (Example 11) Then, an organic polymer / clay composite polymer gel in which the cut surfaces were bonded in the same manner as in Example 4 was obtained except that a load of 20 g per 1 cm ² was applied at room temperature and held for 10 hours. It was. In the tensile test performed in the same manner as in Example 4, in Example 10, strength = 85 kPa and breaking elongation = 1210% were obtained, and in Example 11, strength = 60 kPa and breaking elongation = 850% were obtained.

(Comparative Examples 1 and 2)
A chemically crosslinked (PDMAA) polymer gel was synthesized in the same manner as in Example 1 except that 1 mol% of an organic crosslinking agent (N, N′methylenebisacrylamide) was used instead of clay. In the comparative example 1, the obtained gel was made in the same manner as in Example 1, and in Comparative Example 2 in the same manner as in Example 4, cut surfaces were formed, and bonding was attempted by bonding them together. However, in either case, the polymer gel remained in a state of being easily separated into two, and the polymer gel was not joined.

(Comparative Example 3)
Except for bonding non-cut surfaces, the same experiment as in Example 1 was performed and bonding by bonding was attempted. The measured breaking strength was easily 1% or less of the same gel having no bonding surface. As a result, it was not possible to perform effective bonding.

Claims (4)

  A method for joining a polymer gel having a three-dimensional network structure formed of a polymer (A) of a water-soluble radically polymerizable organic monomer and a water-swellable clay mineral (B), the polymer gel to be joined The polymer gel is characterized in that a cut surface is formed on both or both surfaces and the polymer gel is bonded by bonding the cut surfaces or the cut surface and the non-cut surface together. Joining method.   The method for joining polymer gels according to claim 1, wherein the mass ratio (B / A) of the water-swellable clay mineral (B) to the polymer (A) obtained from the organic monomer is 0.01 to 1. The method for bonding polymer gels according to claim 1 or 2, wherein after bonding the surfaces to be bonded together, one or a plurality of treatments of heating, pressurization and ultrasonic irradiation are performed to bond the two.   The method for joining polymer gels according to any one of claims 1 to 3, wherein the water-soluble organic polymer (C) is applied to the cut surface or the non-cut surface to be joined, and then joined.