Abstract:
The invention herein relates to a thermoplastic suitable for setting bandages and a solventless process for the manufacture of setting bandages therewith. The thermoplastic composition comprises a saturated linear polyester and a resin with low crystallizability and a low softening temperature. The setting bandage made according to this invention can be easily applied to injured parts of a body and the cast resulting therefrom is light, inert, waterproof, ventilative, rigid and shockproof. A method for the manufacture of said setting bandages without the use of solvents is also described in detail.

Description:
INTRODUCTION 
     The invention relates to a new thermoplastic resin composition for setting bandages for orthopedic treatment and a method for the manufacture of the setting bandages therewith. A thermoplastic resin composition is provided which is sufficiently plastic within a relatively low temperature range of 55° to 80° C. such that the setting bandage prepared therewith can readily and quickly be applied to any portion of the human body but would not stick to the hands of the operator, and, after solidification, the case is ventilative, waterproof, not contaminative, inert, highly rigid and shock-proof. The thermoplastic resin can be prepared in an environmentally safe manner without the use of solvents. A method for the manufacture of setting bandages with such a thermoplastic resin has also been developed. 
    
    
     BRIEF DESCRIPTION OF THE FIGURE 
     The FIGURE is a perspective view of an apparatus for the manufacture of a setting bandage according to this invention. The numbers in the drawing indicate the following: (1) the base fabric, (2) tension device, (3) vessel for fluid resin, (4) heater, (5) oil, (6) rolls for adjusting thickness, (7) hot air blast, (8) cooling rolls and (9) take up rolls. 
     BACKGROUND OF THE INVENTION 
     The conventional setting bandage is a gypsum bandage, wherein calcined gypsum (plaster of Paris) is impregnated into a fabric. However, there are many drawbacks to the use of the gypsum bandage. The resulting cast is very heavy. The drying time is very long since a large amount of water is required to cause gypsum to solidify. The cast is difficult to modify after it sets. It loses its strength when exposed to moisture, such as rain, snow or water. As a result, the cast often has to be rewound. A gypsum cast lacks sufficient ventilativity and tends to cause the growth of molds and bacteria. Also, it lacks sufficient transparency to x-rays thereby making x-ray diagnosis difficult. In addition, during manufacture, the pulverized particles of calcined gypsum affect the workmen and may cause them to contract bronchitis. Accordingly, various setting bandages avoiding the use of calcined gypsum have been proposed. For example, Japanese Pat. No. 6116/73, entitled &#34;Bandage for orthopedic surgery, impregnated with ultra-violet-ray hardenable plastic&#34;, Japanese Pat. No. 152586/75, entitled, &#34;Surgery bandage impregnated with photo-hardenable resin&#34;, and Japanese Pat. No. 146786/76, entitled &#34;Photo-hardenable splint for orthopedic surgery&#34;, are hard and light fastening bandages, wherein a bandage of woven, knitted or non-woven fabric having been impregnated with a photo-sensitive resin is adapted to wind or to splint the wounded portion up to a necessary thickness, and then solidified by exposing it to an ultra-violet ray lamp (usually, at about 3,000 A). 
     By virtue of the above-mentioned invention, setting bandages have been greatly improved. A setting bandage which is highly plastic and applicable to any and all parts of the body is available. The resulting cast is very rigid, light and waterproof with improved ventilability and x-ray penetrability. However, because of the high reactivity and the low molecular weight of the polymers employed as the main component of the composition, patients can develop skin irritation and the odor may cause dizziness. Gloves are also necessary for the operator and a dark room is required to handle the photo-sensitive resin. Thus, mass production of the bandage is very difficult. 
     Other setting bandages known in the art are described in the following: 
     Japanese Pat. No. 95435/73 entitled &#34;Thermo-contractive moldings&#34;, Japanese Pat. No. 25086/75 entitled &#34;Thermo-plastic material for bandage or modeling&#34;, Japanese Pat. No. 147190/75 entitled &#34;A material for plastic surgery&#34;, Japanese Pat. No. 95896/77 entitled &#34;Thermo-plastic body supporter&#34;, Japanese Pat. No. 6797/78 entitled &#34;Moldable gypsum material&#34;, and Japanese Pat. No. 64192/77 entitled &#34;Bandage material and stiff-supporting bandage&#34;, wherein, generally, a thermo-plastic resin is coated on or impregnated into a woven or knitted, relatively coarse textured, base fabric prepared from cotton, glass wool or synthetic fiber or mixtures of the above to form into a coiled or sheet bandage, or said thermoplastic resin itself is formed into a plate to be applied to any object. 
     These prior art patents describe the use of relatively high molecular weight polymers to decrease the effects of bad odors. However, these polymers are low in plasticity, are less adhesive, and require high temperatures for softening. They are also less stable. The bandages made therefrom do not produce a good fit. These disadvantages result in a decrease in their use in spite of the improvements. In carrying out the above invention, it was found that no particular room is necessary for working and mass production is possible. However, the high softening temperature and high viscosity of the resins require the use of organic solvents, e.g., toluene, trichloroethylene, trichloromethylene, methylethylketone, tetrahydrofuran, for the coating or impregnation of these resins. Thus, dangers of fire or pollution of the environment can be expected. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Attempts have been made to remove these disadvantages. An excellent resin composition has been prepared. These compositions are sufficiently plastic within a low temperature range. The softened resins do not tend to adhere to the human body, but the bandages prepared therefrom can be easily and quickly applied to the body. After the resin has hardened, the cast has high mechanical strength and high rigidity, is highly durable, waterproof, shockproof and inert. Without the use of solvents, the resin composition can also be coated on or impregnated into fine or coarse textured woven or knitted fabrics consisting of the following or a mixture of the following, cotton, glass wool or synthetic fibers. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     According to the present invention, a resin composition for setting bandages is provided consisting of a saturated linear polyester which is a relatively low crystallizable resin with a relatively low softening temperature. This composition can be coated on or impregnated into thick soft fabrics with large openings without the use of solvents. 
     The embodiments of the invention are described in detail in the following examples which are presented for purposes of illustration and are not meant to limit or define the invention. The words &#34;parts&#34; or &#34;%&#34; relate to weight units unless otherwise stated. 
     Table I shows seven examples of resin compositions, the blending ratios and physical characteristics thereof, e.g., softening temperature, adhesives, waterproofness, strength, viscosity and decomposition temperature. 
     Polyhexa-methylene-adipate is not commercially available. It can be prepared by combining 1,6-hexanediol and adipic acid. A mixture of 1.05 moles of 1,6-hexanediol and 1 mole of adipic acid is heated in a stream of nitrogen gas. When the temperature exceeds the melting point of 1,6-hexanediol, the mixture is agitated. After the rapid dehydrating reaction has completed, an amount, corresponding to 3% of the total weight of the above, of a reaction accelerator, such as calcium acetate, sulfuric acid, potassium carbonate, 4-methyl-benzene sulfonic acid, dibutyltin dilaurate, tetraisopropyl titanate ((iso-PrO) 4  Ti), etc. is added to the mixture, which is then heated to 190° C. The reaction is allowed to take place in a stream of nitrogen until the acid value is 5.0 and the molecular weight is about 10,000 to 13,000 resulting in a white, highly viscose product, polyhexamethyleneadipate. A small amount of titanium oxide or the like is added for the purpose of adjusting the color. 
     Table II shows the properties of the commercially available compositions, Bylon,RA-200 and RV-300 as indicated in Table I. 
     Table III shows method for measuring the characteristics of the various compositions listed in Table I. Namely, plasticity is evaluated by measuring the softening temperature and the differential caloric content; adhesivity is measured by the feeling test, waterproofness is measured by the change in compression strength after soaking in aqueous acidic, alkaline and neutral media respectively; rigidity is evaluated by measuring bending, compression and impression strength; shock-proofness is estimated by the drop test; coatability without solvent is appraised by measuring the viscosity and temperature at which oxidative decomposition occurs. Test samples consist of both planar and cylindrical configurations. The blended compositions were used in tests for coatability. 
     Planar samples can be prepared by melting and mixing the blended composition in a heater kneader at 100°-200° C. to a homogeneous mixture. The molten resin is poured into a 3 mm thick metallic mold, cooled, and cut into rectangular pieces, 35 mm×150 mm. 
     Alternately, the homogeneous mixture can be poured into a heating vessel and heated to 110° C. A base fabric knitted from cotton and glass wool is impregnated with a predetermined amount of the fluid (680 g/m 2 ) in the heated vessel through a heated roller, treated with a blast of hot air and then cooled as a sheet to produce an impregnated fabric with openings of 1 to 3 mm 2 . A preferred thickness of the fabric used is 1 to 7 mm. The sheet is then cut into 10 cm wide bands, and rolled into a coil with a polyethylene film sandwiched between the layers. Then the coiled band is soaked in hot water at 70° C. for approximately 5 minutes to be softened. The band is subsequently wound four layers thick around a 75 mm diameter glass pipe while removing the polyethylene film. The wrapped pipe is allowed to cool. The formed cylinder is separated from the glass pipe. The temperature for oxidative decomposition and viscosity was measured at the same time as for the planar test sample. Conditions and results are indicated in Table III. 
     The method for preparing a bandage incorporating the above-described resin is as follows. The resin composition is heated in vessel 3 (FIG. 1) to 110° C. until it is a fluid with a viscosity of about 250,000 to 350,000 pois. A basic fabric, which may be a soft material with wide openings knitted from a comparatively low density bulky fiber, is drawn out from coil 1 into vessel 3. A predetermined amount in weight per unit area of fluid resin is impregnated onto the base fabric. Any excess is removed. The impregnated fabric is heat treated and then cooled and then wound around drum 9. The product is then cut into sheets of a certain set width and length by using a slitter machine. The sheets are then rolled into coils with a heat resistive film, such as, polyethylene, polypropylene, nylon, polyester or polyvinylchloride films, sandwiched between the layers and finished as a rolled setting bandage. 
     The thermoplastic bandage prepared in the above-described manner can be applied onto the body in the following manner. The coiled bandage is soaked in hot water for 3 to 5 minutes to be heated to about 70° C., softening the impregnated resin and rendering it to be sufficiently self-adhesive. The bandage is taken out of the hot water and any excess water is removed. The bandage is applied to the injured portion of the body on which a material such as cotton bandage, sponge, non-woven cloth or felt has been applied as a cushion. The bandage is wound 3 to 4 layers thick. Meanwhile, the edges and angles can be adjusted. After this, the wound bandage is cooled, naturally, or by force, to allow it to solidify into a strong, rigid and shockproof setting cast. As can be observed from the above description as well as the illustrative examples, the bandage is softenable at relatively low temperatures (55°-80° C.) and will adhere to itself. Therefore, it can readily fit any portion of the body; and, because of its manipulatability at low temperatures and the possibility of putting additional layers on previously wound bandage when necessary, it can meet a wide range of demands. Further, because the resin does not stick to the operator&#39;s hand nor to the injured portion of the body, the operation can be performed quickly and cleanly. The set bandage is durable, waterproof, rigid and highly shockproof and can be relied on for a long period of use. In addition, because of its high strength on setting, a relatively small amount of bandage is required, it is thus more economical. It is also light and ventilative, therefore, the patient is more comfortable while wearing the cast. 
     It should also be emphasized that the thermoplastic resin of the setting bandage according to this invention is very stable at high temperatures and if heated to a high temperature will not undergo significant oxidation, evaporation or decomposition. Thus, the viscosity can be lowered by raising the temperature to facilitate the coating of the base fabric without the need of using a solvent. 
     
                                           TABLE I__________________________________________________________________________                                           Viscosity and            Parts                Softening     Water-       DecompositionNo.   Composition   mixing                Temperature                       Adhesiveness                              proof                                  Strength temperature__________________________________________________________________________1  Polyhexa methylene adipate            100 55° C.-61° C.                       Not adhesive                              no  A.                                    Bending                                           19.7 × 10.sup.4   Bylon RA-200  50         to finger                              change                                     3.3 Kg                                           cps/120° C.   Titanium Oxide             5                    B.                                    Compression                                           250° C.   Coloring agent            0.3                     16.8 Kg                                  C.                                    Impulsive,                                    no breakage2  Polyhexa methylene adipate            100 55° C.-63° C.                       Not adhesive                              no  A.                                     2.3 Kg                                           23 × 10.sup.4   Bylon RV-300  50         to finger                              change       cps/120° C.   Titanium Oxide             5                    B.                                    17.5 kg                                           250° C.   Coloring Agent            0.3                   C.                                    No breakage3  Polyhexa methylene adipate            100 51° C.-58° C.                       Not adhesive                              no  A.                                     1.4 Kg                                           18.3 × 10.sup.4   IBMA          50         to finger,                              change       cps/120° C.   (Isobutil Methacrylate)  Inferior in                                  B.                                    12.4 Kg                                           230° C.   Titanium Oxide             5         self-adhesion   Coloring Agent            0.3                   C.                                    No breakage4  Polyhexa methylene adipate            100 55° C.-57° C.                       Slightly                              no  A.                                     3.0 Kg                                           25.8 × 10.sup.4   Caprolacton   50         adhesive                              change       cps/120° C.   Titanium Oxide             5         to finger  B.                                    15.3 Kg                                           220° C.   Coloring agent            0.3                   C.                                    No breakage5  Polyhexa methylene adipate            100 50° C.-55° C.                       Slightly                              no  A.                                    1.2 Kg 18.5 × 10.sup.4   Polyvinylether            30         adhesive                              change       cps/120° C.   Titanium oxide             5         to finger  B.                                    9.4 Kg 180° C.   Coloring agent            0.3                   C.                                    deformed6  Polyhexa methylene adipate            100 55° C.-75° C.                       No     no  A.       32 × 10.sup.4   EVA           50         Adhesiveness                              change       cps/120°  C.   (Ethylene vinyl acetate)            B.       250° C.   Titanium oxide             5   Coloring agent            0.3                   C.                                    damaged7  Polyhexa methylene adipate            100 55° C.-83° C.                       No     no  A.                                    1.8 Kg 38 × 10.sup.4   PE            50         Adhesiveness                              change       cps/120° C.   Titanium oxide             5                    B.                                    8.3 KG 250° C.   Coloring agent            0.3                   C.                                    deformed__________________________________________________________________________ 
    
     
                                           TABLE II__________________________________________________________________________Property   Bylon, RA-200              Bylon,RV-300                      Note__________________________________________________________________________Form       1/8&#34; dice              thin plateColor      Colorless or              Colorless or      light yellow              light blueSmell      no smell              no smellSolubility para-meter (SP) about 9.2              about 8.9Humidity % 0.4     0.5     25° C., 60RHTensile St.Kg/cm.sup.2      500     50      D638-61TMaximum elon-gation %   3       700     D638-61THardness(Shore D)  80      25      25° C.Specific gravity      1.255   1.192   25° C.Index ofrefraction 1.55    1.54Limit viscosity      0.53    0.70    30° C. Phenol/                      tetrachloro-                      ethaneMolecular  15,000- 20,000-weight     20,000  25,000Acid value 1.68    1.08    = 6/4, 0.5%                      (assumption)Glass TransitionTemp. °C.      67      6Softening point°C. 163     123     JIS-K-2531                      (Annular                      sphere Pr.)Softening point°C. 135     90      JIS-K-2425                      (Mercury                      process)Melting temp.      180-200 140-160Melt.Viscosity,poise      2900    3900    Phot-chem.flow-                      tester, 200° C.                      30 l/secDecrease of                200° C. × 5 hrweight through             in airheating %  0.4     0.5     (moisture)tan        0.3     9.5     25° C.tan        9.0     0.5     70° C.Specificinductivity      3.8     5.2     25° C.                      (D150-59T)Specificinductivity      5.0     6.0     70° C.                      (D150-59T)Solid spc.resistance.cm        7.2 × 10.sup.16              1.3 × 10.sup.15Puncturevoltagev/mil      6500    2200    at 1 milUltra violet      Shut off ultra violet rayray absorption      shorter than 300 AVapourpermeability      40g/24hr/m.sup.2 /mil/atm                      ASTM-E96Oxygen permeability      0.3-0.4g/24hr/m.sup.2 /mil/atm                      ASTMD-143463__________________________________________________________________________ 
    
     
                       TABLE III______________________________________Itemtesting Process    Conditions and Equipment______________________________________Plas- Softening  Test piece is kept horizontally betweenticity tem-       two supporting points, at the middle perature   point of which 20 g of weight is            applied, and temperature is measured            at the point where 20 mm of variation            is seen. DTA        About 1.5 mg of test piece contained in            an Al-cell is measured by a differential            thermal analyzer.Ad-   feeling    Test piece having been heart-softenedhesive test       by hot water or 80° C. is pushed by finger,ness             and taking the finger away, adhesiveness            is appraised.Water- Compres-   A cylindrical test piece is soaked,proof sion       respectively, within solutions 1N--HCl, test       1N--NaCl and in water from water work            for 72 hours, and taken out to be washed            by water, then removing water therefrom,            and compression test was performed.Rigid- Bending    Horizontally keeping a plate test pieceness  strength   between two supporting points, with a test       weight added at the middle point, max.            load and deformation are measured. Compres-   By means of stro-glass tester, load of sion       deformation of 6.3 cm in a cylinder test test       piece is measured.Resis- Drop       A steel plate (10 × 10 cm) of 2 Kg istance test       dropped from 30 cm height on a cylinderagainst          test piece, and tested whether itIm-              cracked or not.pulseCoat- temp-      Tested by means of DTA.ing   eraturecharac- of oxi-teristic dizing decom- position Viscosity  Having the test piece heated to 120° C.,            it is tested by rotary viscosity meter.______________________________________