KR930002267B1 - Die-casting materials for supporting humanbody - Google Patents

Abstract

The polymeric material comprises (a) polymeric substrate, (b) thermoplastic rubber and (c) filler. The weight ratio of (a) to (b) is 5:1 - 1:1 and the ratio of a mixture (a) and (b) to (c) is 8:1 - 2:1. The polymeric substrate is polycaprolactone having a molecular weight of at least 10,000 (pref. above 25,000), and the thermoplastic rubber is syndiotactic 1,2-polybutadiene having a boiling point of 52 deg.C and a crystallinity of 25 %. The filler is synthetic silica having a particle size of 20-50 nm. The material is used for supports for surgical purposes.

Description

Polymer material for orthopedic support

The present invention relates to a polymeric material for moldable orthopedic supports used to fix each part of the body.

Orthopedic supports refer to moldings used to support, fix, protect, stabilize, and bind to fracture sites or fixation treatment sites, and include plaster bands, splints, braces, and braces.

In general, gypsum bandages have conventionally been used to fix fractures. However, gypsum bandages are very heavy and have no air circulation, which damages the skin at the fracture site, is hardly permeable to X-rays, weak to water and impact, takes time to cure, and is difficult to remove after cure. There are drawbacks such as difficulty. Therefore, a gypsum substitute material by synthetic polymer material has been studied.

Synthetic polymer material for the support has the following advantages, unlike gypsum bandages.

1) It is easy to mold and reshape.

2) Light and durable.

3) Excellent X-ray transmittance.

4) Resistant to water and shock.

5) Good ventilation, less damage to the skin.

6) Simple handling and aesthetic appearance.

7) It is easy to store and has a suitable working time (molding time) to mold.

The prerequisite for the support polymer material is a thermoplastic resin having moldability, a crystalline polymer having excellent mechanical properties, suitable melting point (Tm = 50-80 ° C.), high molecular weight that can be easily processed, and suitable molding time. .

As a polymer material satisfying the above conditions, there is ε-polycaprolactone (hereinafter referred to as "polycaprolactone"). British Patent No. 1,366,091 prepared a polymer support by adding filler to polycaprolactone of moderate molecular weight with a melting point of about 60 ° C. These polycaprolactones have high flexural strength and flexural modulus, but are not only sticky at melting points, are short in molding time, and have no self adhesiveness. The addition of fillers has the disadvantage of poor flexibility.

In order to eliminate the disadvantage of inflexibility due to the addition of filler, according to the publication published by Interox Chemical (UK), 1-10% of organic peroxide was added to crosslink the polycaprolactone. However, the crosslinked polycaprolactone has a disadvantage of showing elastic recovery after solidification. In addition, US Pat. No. 4,240,415 uses polycaprolactone crosslinked by electron radiation, but has a high elongation at melting and a short molding operation time.

To produce more effective orthopedic supports, U.S. Patent 4,274,983 describes 5-20 phr of natural rubber or cis-1,4-polybutadiene, 0-10 phr of ionomers in polycaprolactone of 70-80 phr (parts perhundred of resin). ionomer) and a filler using 10-30 phr of silica or calcium silicate, but the drawback is too large. In addition, various rubbers have been blended to make up for the shortcomings of polycaprolactone. In other words, as a thermoplastic rubber, trans-1,4-polyisoprene, trans-1,4-polybutadiene (US Patent 4, l44,223), ethylene-vinylacetate (European patent 102,369), polyurethane (German patent 2,519,992) Neoprene rubber (German patent 2,519,993), styrene-acrylonitrile copolymer (UK patent 2,125,803) and styrene-butadiene-styrene block copolymer (European patent 169,037) were used to prepare orthopedic polymer supports.

Unlike the orthopedic polymer support of the prior art described above, the present invention, while maintaining high flexural strength and flexural modulus, almost no flow deformation during elastic recovery and melting, has a suitable molding operation time, light and improved adhesion It is to manufacture a polymer material for the moldable support.

In the related support moldings, the substrate polymer is polycaprolactone, precisely polycaprolactone (PCL, trade name Capa 650, Interox Chemical). The molecular weight of the polycaprolactone used is at least 10,000, preferably at least 25,000, and a high molecular weight is easy to process.

The thermoplastic rubber used in the present invention is syndiotactic 1,2-polybutadiene (RB, trade name RB 820, manufactured by Japan Synthetic Rubber, Inc.), which is lighter than other rubber products, can improve transparency and breathability, and is also a thermoplastic resin. And having the intermediate properties of the thermoplastic rubber has the advantage that can improve the adhesion and prolong the molding operation time. The 1,2-polybutadiene used was a thermoplastic rubber having a significantly low softening point of about 52 ° C. and a crystallinity of about 25%, and was used to compensate for the disadvantages of polycaprolactone described above in the present invention.

In the present invention, the mixing ratio of polycaprolactone and 1,2-polybutadiene is preferably about 5: 1 to 1: 1. When this mixing ratio is 5: 1 or more, the composition is hard and difficult to process, and the molding work time is shortened. Moreover, when this ratio is 1: 1 or less, flexural yield strength and flexural modulus fall remarkably. Therefore, the most ideal mixing ratio is about 4: 1 to 3: 1.

Fillers, one of the components of the compositions of the present invention, have been used to reduce tackiness during melting during processing and to improve flexural strength and flexural modulus. As a filler, natural silica and synthetic silica may be used, but synthetic silica (trade name Zeosil 155, Hanbul Chemical Co., Ltd.) having a relatively small bulk density was superior. The particle size of the silica should be at least 50 nm or less, more preferably on the order of 25 nm. Silica used in the present invention is fumed silica, having a particle size of about 20 nm, excellent dispersibility, and short mixing time.

In the present invention, the mixing ratio of the polycaprolactone, the polymer component of 1,2-polybutadiene, and the filler is about 8: 1 to 2: 1. If the ratio is 8: 1 or more, the composition is too sticky and difficult to process, and if the ratio is 2: 1 or less, flexibility is lost and the molded product is easily broken by stress. Therefore, the most suitable mixing ratio is ideally 6: 1 to 4: 1.

Crosslinking of polycaprolactone or thermoplastic rubber is generally accomplished by adding electromagnetic radiation or organic peroxides. In the present invention, benzoyl peroxide was used as the crosslinking agent.

In the present invention, the degree of crosslinking is particularly low, so that not only polycaprolactone but also 1,2-polybutadiene are simultaneously crosslinked. The amount of the benzoyl peroxide added is preferably 0.1-1.0 phr of the polymer component. If less than 0.1 phr is used, there is almost no crosslinking effect, and if it is more than 1.0 phr, the rubber properties increase to show elastic recovery and poor formability.

Physical properties of the obtained thermoplastic polymer blend were evaluated by measuring mechanical and thermal properties. Flexural (yield) strength and flexural modulus were measured by the method of ASTM D 790-66, Shore D hardness was measured according to ASTM D 2240-81 using Durometer type D. In addition, the Vicat softening point was measured according to ASTM D 1526-76. Melting point (Tm), crystallization temperature (Tc) and molding time were measured using differential scanning calorimetry (DSC) to measure the thermal behavior of polymer blends. Analyzed. In particular, molding operation time was evaluated by analyzing isothermal crystallization at 20 ° C. That is, the polymer blend was melted at 80 ° C. and then rapidly cooled to 20 ° C., and the time at which the crystallization was terminated at an isothermal state was the molding operation time. This was performed after heating the polymer material when the orthopedic polymer support was actually applied. It takes time to harden and harden.

The polymer blend of the present invention can be easily processed by conventional methods such as injection processing, extrusion processing and compression molding, it is advantageous that the polymer support is produced by cutting after extrusion into a sheet form. In particular, it is a feature of the present invention that the thermoplastic rubber and the synthetic silica are added to reduce the adhesiveness at the time of melting and thereby have excellent workability.

Example 1

Polycaprolactone was placed in a mixer and gelled at 80 ° C., then 1,2-polybutadiene was added and mixed at 120 ° C. for 10 minutes. At this time, stearic acid (Lucky) as a lubricant, Irganoxl010 (Ciba Geigy) as an antioxidant, and titanium dioxide (Du Pont) as a pigment, Permanent Orange (Switzerland Chemistry) and Solvaperm Red G (Hoechst) were added. The mixed sample was molded at 130 ° C. and l500 psi for 7 minutes using a compression molding machine. Table 1 shows the physical property changes of various PCL / RB blends, but the mechanical properties of flexural yield strength, flexural modulus and Shore D hardness decreased with increasing RB content, but the Vicat softening point, melting point, and crystallization temperature were decreased. And the molding work time increased significantly. Therefore, considering the high flexural strength, flexural modulus and proper molding time, which are important prerequisites for orthopedic polymer supports, the mixing ratio of PCL / RB should be at least 3: 1.

TABLE 1 Property Changes of Various PLC / RB Blends

Example 2

A polymer blend was prepared in the same manner as in Example 1 except that the filler was further added. Table 2 shows the physical property change of the PCL / RB / Zeosil blend, the mechanical properties increase with increasing Zeosi1 content, but the molding operation time is reduced and the flexibility is lost. In general, the mechanical properties that can be used as polymer materials for orthopedic support are as follows: flexural (yield) strength is more than 125kg / ㎠, flexural modulus is more than 4,000kg / ㎠ and the hardness is as high as possible, and the molding work time is about 4-5 Minutes are preferred. Therefore, when the ratio of PCL / RB is 4: 1 and the content of Zeosil is 15 phr, the orthopedic polymer support is most suitable.

[Table 2] Changes in Physical Properties of PCL / RB / Zeosil Blends

Example 3

It is the same as Example 2 except having added benzoyl peroxide further as a crosslinking agent. Table 3 compares the physical property change after crosslinking at 120 ° C. for 10 minutes by adding 0.5 benzoyl peroxide to a PCL / RB (4: 1) blend having a zeosil content of 15 phr. The crosslinked moldings had slightly reduced molding time compared to uncrosslinked but improved mechanical properties.

TABLE 3 Influence of crosslinking on PCL / RB / Zeosil blends

Claims (9)

a) a matrix polymer, b) a thermoplastic rubber, and c) a filler, wherein the weight ratio of components a) to b) is 5: 1 to 1: 1, and the weight ratio of the mixture of components a) and b) to c) The polymer material for moldable orthopedic support, characterized in that the 8: 1 to 2: 1. The polymer material according to claim 1, wherein the substrate polymer a) is polycaprolactone. The polymeric material of claim 1, wherein the thermoplastic rubber b) is syndiotactic 1,2-polybutadiene. The polymer material according to claim 1, wherein the filler c) is synthetic silica. The polymeric material of claim 4, wherein the synthetic silica is silica having a particle size of 20 to 50 nm. The polymer material according to any one of claims 1 to 5, wherein the weight ratio of component a) to component b) is 4: 1 to 3: 1. The polymeric material according to claim 1, wherein the weight ratio of the mixture of component a) to component b) and component c) is from 6: 1 to 4: 1. The polymer material according to claim 1, further comprising benzoyl peroxide as a crosslinking agent. The polymer material according to claim 8, wherein the content of the crosslinking agent is 0.1 to 1.0 phr with respect to the mixture of the matrix polymer components a) and b).