JPH09234241A - Orthosis having thermally deforming property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive orthosis which can easily be thermal- deformed from a standard shape to a user-specific shape and reduces the disposal problem after use. SOLUTION: A thermally deformable orthosis is made from a poly-lactic acid resin with a glass-transition point of 40 to 80 deg.C. The resin is formed in a standard orthosis shape, the orthosis is thermal-deformed at a temperature higher than the glass-transition point and lower than the molding temperature (for example, bathed in hot water), then the orthosis is cooled to a temperature lower than the glass-transition point with keeping the deformed shape (for example, naturally cooled in the air) and fixed its deformed shape. As mentioned above, a standard shape orthosis is thermal-deformed and a user-specific shaped orthosis 1 is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-deformable orthosis made of an aliphatic polyester biodegradable resin. More specifically, the present invention relates to a heat-deformable orthosis that is attached to a body for assisting, correcting, or reinforcing the body in the fields of medical care, welfare, clothing, sports, and the like.

[0002]

2. Description of the Related Art As the above-mentioned orthosis, there are casts, splints, artificial limbs, corsets used in the field of orthopedics and clothing used for fractures. Conventionally, the plaster is made of gypsum, the splint is made of plastic or wood, and the artificial limb is made of plastic, both of which are molded into a general shape. Therefore, it has not been sufficiently adapted to the user's symptoms and body shape. In addition, a silicon resin is used for a portion requiring flexibility, but this is also a general shape, and it is difficult to correct the shape according to the symptom progress of the user.

Recently, a polyurethane resin having a shape-memory property (trade name: Diary, manufactured by Mitsubishi Heavy Industries) has been tested as a material for casts for people with limbs, especially lower limbs, in order to better suit the symptoms and body shape of the user. It is used for. This is to form a diary into a general shape as a cast and heat the cast again to correct the shape according to the symptoms and body shape of each user.

[0004]

However, it is difficult to control the temperature at the time of molding, and the polyurethane resin generally has a problem in terms of moldability and is expensive. In addition, there is the problem of waste disposal after use. That is, when the polyurethane resin is incinerated, harmful isocyanate is generated, and the land to be buried is limited, and these treatments are serious problems. In addition, when it is discarded in the natural environment, it remains without being decomposed due to the stability of the resin, impairing the landscape, and also causes problems such as polluting the living environment of marine life.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, to easily perform heat transformation from a general shape to a shape suitable for each user, and to dispose of waste materials after use. An object of the present invention is to provide an inexpensive brace that alleviates the above problem.

[0006]

As a result of intensive studies to solve the above problems, the present inventor has found that the glass transition point is 25 to
It has been found that a device which can be easily thermally deformed can be obtained by using an aliphatic polyester biodegradable resin at 100 ° C. as a material, and the present invention has been completed.

That is, the heat-deformable orthosis of the present invention comprises an aliphatic polyester biodegradable resin having a glass transition point of 25 to 100 ° C.

Hereinafter, the present invention will be described in detail. Examples of the aliphatic polyester biodegradable resin having a glass transition point of 25 to 100 ° C. in the present invention include poly (α-hydroxy acid) such as polyglycolic acid and polylactic acid; poly-β-hydroxybutyric acid and the like. Poly (β-hydroxyalkanoate); poly (ω-hydroxyalkanoate) such as poly-ε-caprolactone; polyalkylene alkanoate such as polybutylene succinate and polyethylene succinate. These aliphatic polyester-based resins generally have a melting point of 60 to 200.
It has a weight average molecular weight of about 100,000 to 300,000.

These aliphatic polyester biodegradable resins have shape memory characteristics. That is, it is generally possible to deform at a temperature above the glass transition point, and the deformed shape can be fixed by cooling to a temperature below the glass transition point while maintaining the deformed shape. It has the property of recovering its original shape by heating the body again to a temperature above the glass transition point.

Therefore, the equipment obtained by molding these aliphatic polyester resins into a general shape can be easily formed into a shape suitable for each user by setting the temperature to the glass transition temperature of the resin or higher. It can be transformed. From the viewpoint of ease of thermal deformation, the glass transition point of the resin is preferably about 40 to 80 ° C.

In the present invention, among the above-mentioned aliphatic polyester biodegradable resins, polylactic acid resin is excellent in biodegradability, has high biosafety, and absorbs lactic acid which is a decomposed product in vivo. It is preferable because of its low price, transparency, and good colorability. For example, the biodegradation property of poly-L-lactic acid resin is very excellent, showing a degradability of 93% in the biodegradability test of 44 days in compost, while the degradability of cellulose is 73%. Further, the price of the poly-L-lactic acid resin is low, about 1/4 to 1/3 of the price of the polyurethane shape memory resin.

In the present invention, the polylactic acid resin has a melting point of 16
It is preferably 0 to 200 ° C, a glass transition point of 45 to 75 ° C, and a weight average molecular weight of 150,000 to 250,000. When the glass transition point is in such a range, it is easy to raise the temperature to the glass transition point or higher when applying the deformation, and the deformed shape can be obtained by cooling to a temperature lower than the glass transition point while maintaining the deformed shape. Can be fixed and the deformed shape can be maintained near room temperature. More preferable glass transition point is 50 to 60
° C. When the weight average molecular weight is less than 100,000, the polymer molecular chains are less entangled with each other and the shape memory property is difficult to be exhibited. On the other hand, when the weight average molecular weight exceeds 300,000, moldability tends to deteriorate.

The polylactic acid resin is poly-L-lactic acid or poly-DL-lactic acid containing D-lactic acid as a constitutional unit. The constituent content of the D-lactic acid unit in the poly-DL-lactic acid is preferably up to 40 mol%. When the D-lactic acid unit exceeds 40 mol%, the molecular weight of the polymerized poly-DL-lactic acid becomes extremely low (10,000 or less). The preferred polylactic acid in the present invention is poly-L-lactic acid or poly-DL-lactic acid containing up to 20 mol% of D-lactic acid as a constitutional unit.

Further, the polylactic acid resin may be a lactic acid-based copolymer obtained by copolymerizing a lactic acid monomer or another component copolymerizable with lactide. Examples of such other components include dicarboxylic acids having two or more ester bond-forming functional groups, polyhydric alcohols, hydroxycarboxylic acids, lactones, and the like.

Examples of the dicarboxylic acid include succinic acid, azelaic acid, sebacic acid, terephthalic acid and isophthalic acid. Examples of polyhydric alcohols are aromatic polyhydric alcohols such as those obtained by addition-reacting ethylene oxide on bisphenol, ethylene glycol, propylene glycol, butanediol, hexanediol, octanediol, glycerin, sorbitan, trimethylolpropane, neopentyl glycol, etc. Examples thereof include ether polyhydric alcohols, ether glycols such as diethylene glycol, triethylene glycol, polyethylene glycol and polypropylene glycol. Examples of the hydroxycarboxylic acid include glycolic acid, hydroxybutylcarboxylic acid, and others described in JP-A-6-184417. As the lactone, glycolide, ε-caprolactone glycolide, ε-
Caprolactone, β-propiolactone, δ-butyl lactone, β- or γ-butyrolactone, pivalolactone, δ-valerolactone and the like can be mentioned.

Polylactic acid can be synthesized by a conventionally known method. That is, JP-A-7-33861, JP-A-59-96123, and Proc.
Vol. 3, pp. 3198-3199, or by direct dehydration condensation from lactic acid, or ring-opening polymerization of lactic acid cyclic dimer lactide.

When direct dehydration condensation is carried out, L-lactic acid, D
-Lactic acid, DL-lactic acid, or any of these mixtures of lactic acid may be used. Also, when ring-opening polymerization is performed, L-lactide, D-lactide, DL-lactide,
Any lactide of meso-lactide or mixtures thereof may be used.

The lactide synthesis, purification and polymerization procedures are described, for example, in US Pat. No. 4,057,537, published European patent application No. 261572, Polymer Bull.
etin, 14, 491-495 (1985), and M.
acromol Chem. , 187, 1611-16
28 (1986) and the like.

The catalyst used in this polymerization reaction is not particularly limited, but a known lactic acid polymerization catalyst can be used. For example, organic tin compounds such as tin lactate, tin tartrate, tin dicaprylate, tin dilaurate, tin dipalmitate, tin distearate, tin dioleate, α-tin naphthate, β-tin naphthate, tin octylate. , Powdered tin; zinc dust, zinc halide, zinc oxide, organic zinc compounds; titanium compounds such as tetrapropyl titanate; zirconium compounds such as zirconium isopropoxide; antimony compounds such as antimony trioxide. You can Among these, a catalyst composed of tin or a tin compound is particularly preferred from the viewpoint of activity. The use amount of these catalysts is generally about 0.001 to 5% by weight based on lactide.

The polymerization reaction can be carried out in the presence of the above-mentioned catalyst, usually at a temperature of 100 ° C to 200 ° C, though it depends on the catalyst species. It is also preferable to carry out two-step polymerization as described in JP-A-7-247345.

In the present invention, an aliphatic polyester biodegradable resin may be added to a plasticizer (phthalate ester, etc.), a stabilizer (calcium stearate, etc.), a colorant (red lead yellow lead, titanium oxide, etc.) as required. ), Filler (calcium carbonate, clay, talc, etc.), antioxidant (alkylphenol, organic phosphite, etc.), ultraviolet absorber (salicylate, benzotriazole, etc.), flame retardant (phosphate, antimony oxide, etc.) ), Antistatic agents, antibacterial agents, and other conventionally known additives.
The blending amount of these can be appropriately determined according to the purpose of use.

In the present invention, the method of blending the above-mentioned various additives with the aliphatic polyester biodegradable resin is not particularly limited and can be carried out by a conventionally known method. For example, a mill roll, a Banbury mixer, a super mixer, a single-screw or twin-screw extruder may be used for mixing and kneading.

The resin composition thus kneaded is
It is molded into a general shape of various appliances at a temperature equal to or higher than the melting point of the resin. This molding can be performed by a molding method such as extrusion molding, injection molding, vacuum molding, compression molding, or the like, as in general plastics. The molding temperature is usually about 100 to 300 ° C.

Next, the equipment having a general shape obtained is deformed at a temperature not lower than the glass transition point of the resin and lower than the molding temperature, and then cooled to a temperature lower than the glass transition point of the resin to be deformed. By fixing the shape, it is possible to obtain a brace having a shape suitable for each user.

The deformation is carried out at a temperature above the glass transition point of the resin and below the molding temperature. The lower limit of the temperature that gives deformation is
Usually, the temperature is not lower than the glass transition point, but it is also possible to give the deformation at a temperature lower than the glass transition point. On the other hand, the upper limit of the deformation temperature is lower than the molding temperature. When a deformation is applied at a temperature higher than the molding temperature, a new shape is given to the molded body.

Upon deformation, the molded body is placed in such an atmosphere of temperature, for example, in heated air, heated water, or steam, and any suitable means such as bare hands, suitable molds, rolls, tensioning devices, and squeezing devices are used. It can be performed using the device.
If the glass transition point of the resin is about 40 to 80 ° C., it can be easily performed by immersing the appliance having a general shape in warm water having a temperature slightly higher than this temperature.

When the orthosis thus deformed is cooled to a temperature below the glass transition point while maintaining the deformed shape, the orthosis having the fixed deformed shape is obtained, and the deformed shape is maintained near room temperature. can do. Cooling
For example, it can be performed by naturally cooling the deformed orthosis in the air. In this way, the orthosis having a general shape can be thermally deformed, and the orthosis having a shape suitable for each user can be obtained.

The orthosis having a shape suitable for each user is
When the temperature is lower than the molding temperature and higher than the deformation temperature, the original general shape can be restored. Generally, the higher temperature shortens the time required for shape recovery. The shape recoverability in this case is as excellent as that of the conventional shape memory resin (polyurethane or the like). As described above, by re-thermally deforming the brace that has been restored to the general shape, the shape can be repeatedly corrected according to the progress of the symptoms of the user.

The heat-deformable orthosis of the present invention can be easily heat-deformed, so that a shape suitable for each user can be obtained from a general shape. . In addition, since the device of the present invention has a biodegradable resin as a constituent material and has biodegradability, it can be easily disposed of after use.

In the present invention, as the aliphatic polyester biodegradable resin, polylactic acid resin is preferable, and poly L lactic acid resin is particularly preferable.

[0031]

EXAMPLES The present invention will be described in more detail below with reference to examples.

100 parts by weight of L-lactide (manufactured by Shimadzu Corporation), 0.05 part by weight of lauryl alcohol, and 0.2 part by weight of tin octylate (“Cosmos 29”, a catalyst for ring-opening polymerization manufactured by Gold Schmidt). , Was fed to the raw material supply section of the twin-screw kneading extruder. The cylinder temperature was 190 ° C., the rotation was 60 rpm in the same direction, and nitrogen gas was supplied from the supply port. The average residence time in the twin-screw kneading extruder was 15 minutes. The obtained polymer was extruded from a nozzle having a diameter of 2 mm. This was cooled and solidified, and then cut to obtain a poly-L-lactic acid resin chip. The obtained chips had a weight average molecular weight of 180,000, a melting point of 178 ° C., and a glass transition point of 58 ° C.

The above poly-L-lactic acid resin was mixed with a twin-screw extruder for 180
It was hot melt extruded at 0 ° C to form a transparent sheet having a thickness of 0.1 mm. An example is shown in which this sheet is cut into a size of 180 mm × 150 mm and used as a cast for wrist fracture.

The obtained sheet was immersed in a hot water bath at 70 ° C. for 2 seconds. As shown in FIG. 1, the sheet (1) taken out from the warm water tank was wound around the wrist and fixed for 15 seconds so that the short side was in the length direction of the arm. The sheet was naturally cooled in 15 seconds, the sheet temperature became about 30 to 35 ° C., and a cast having a fixed deformed shape was obtained. This was fixed with adhesive tape and bandaged. This cast fits the shape of the examiner's wrist very well.

After the cast has been used for a certain period of time, it is heated and deformed by a dryer for 1 minute, removed from the wrist, and then,
When immersed in a 75 ° C. warm water tank for 2 seconds, the original sheet shape was recovered. This sheet could be used as a cast again.

[0036]

The heat-deformable orthosis of the present invention is generally composed of an aliphatic polyester biodegradable resin having a glass transition point of 25 to 100 ° C., as described above. The shape can be easily transformed into a shape that suits the body shape and symptoms of each user, and disposal after use is easy. As a result, unlike the conventional case, special specifications corresponding to each user are not required, and an orthosis having a shape suitable for each person can be provided at low cost at each site.

In particular, in a device using a polylactic acid-based resin as the aliphatic polyester biodegradable resin, the polylactic acid-based resin has excellent biodegradability, has high biosafety, and produces lactic acid which is a decomposed product. It is very useful because it is absorbed in the body, is inexpensive, is transparent, has good colorability, and has excellent antibacterial properties.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a specific example of the orthosis having thermal deformability of the present invention.

[Explanation of symbols]

 (1)… Heat deformable sheet

Claims (2)

[Claims] 1. A heat-deformable orthosis comprising an aliphatic polyester biodegradable resin having a glass transition point of 25 to 100 ° C. 2. A heat-deformable orthosis comprising a polylactic acid-based resin having a glass transition point of 40 to 80 ° C.