FR2721037A1 - Mixt., for mfr. profiles - Google Patents

Abstract

The mixt. for the mfr. of profiled prods. in a plastic based on polycaprolactone contains, w.r.t. 100 pts.wt. of polycaprolactone, (a) 5 - 25 pts. of micronised mineral carbonates and (b) 5 - 25 pts. of a linear thermoplastic elastomer comprising styrene-ethylene/butylene-styrene (DEBS) or styrene-butadiene-styrene (SBS).

Description

MIXTURE FOR THE MANUFACTURE OF PROFILED PRODUCTS
PLASTIC MATERIAL BASED ON POLYCAPROLACTONE. PLAOUES
AND ORTHOPEDICALLY STRAPS MADE FROM THESE
MIXTURES.

 The invention is a mixture for the manufacture of profiled plastic products based on polycaprolactone; it also relates to plates produced from these mixtures, in particular for the manufacture of orthopedic splints.

 As is known, "polycaprolactones" are high molecular weight linear thermoplastic homopolymers of polyester based on ltepsilon-caprolactone. These products, which have the property of melting at temperatures in the region of 60 ° C., can be crosslinked with peroxides, such as, for example, dicumyl peroxide, benzoyl peroxide, which can be extruded into plates, which, by softening when hot, can be shaped into orthopedic splints.

Although widely used, this technique for making orthopedic splints has many disadvantages, including
- the manufacturing difficulty linked to the presence of peroxides, compounds
difficult to handle due to the risk of explosion,
- a sticky feel of the plates obtained,
- the risk of decomposition of peroxides and solidification
when the temperature of the extruders is too high,
- the need to conform the splint very quickly, at most
within thirty seconds after softening,
- finally, the presence of significant withdrawal and the difficulty of
remodeling.

In addition, these splints have other disadvantages, such as
- the absence of elastic memory,
- the impression of swelling in water,
- lack of extensibility,
- the lack of dimensional stability after soaking in water at
60-65 "C for softening.

 The invention overcomes these drawbacks.

 It relates to a mixture for the manufacture of profiled plastic products based on polycaprolactone, in particular for the manufacture of plates and more particularly of orthopedic splints, not having the above drawbacks.

This mixture for the manufacture of profiled plastic products based on polycaprolactone, is characterized in that per hundred parts by weight of polycaprolactone, it also contains:
from five to twenty-five (5 to 25) parts of mineral carbonates
micronized,
from five to twenty-five (5 to 25) parts of an elastomer
linear thermoplastic, chosen from the group comprising
styrene-ethylene / butylene-styrene (SEBS) and styrene-butadiene
styrene (SBS).

 In other words, the invention consists in making mixtures of polycaprolactone for the conformation in plates, and more precisely of orthopedic splints, to no longer use peroxidized polycaprolactones, but to a specific mixture of these polycaprolactones with micronized mineral carbonates and with a SEBS or SBS elastomer.

 Surprisingly, the use of these mixtures leads to products having an excellent feel, easy to use, easy to reshape and allowing longer conformation times.

 It is important that the composition contains from five to twenty-five (5 to 25) parts of micronized carbonates and of elastomer, preferably in the vicinity of twenty parts of each of these two compounds.

 It has been observed that if the proportion of one of these compounds is less than five (5) parts, no effect is obtained. Likewise, if this proportion exceeds twenty-five (25) parts, the elasticity modulus of the plates obtained is increased in the long direction, but it is decreased in the transverse direction and there is an unnecessary additional cost without significant improvement. As already said, preferably, these two compounds are each present in an amount of twenty (20) parts.

 As inorganic carbonates, calcium carbonates micronized by a known technique are preferably used, having an average particle size of between one and twenty micrometers, preferably from three to five micrometers.

 As an elastomer, use is essentially made of a synthetic thermoplastic elastomer, the chemical composition of which is essentially of the linear tri-sequenced type: styrene-ethylene / butylene styrene (SBS) in which, after implementation, the terminal blocks of polystyrene physically crosslink trapping the elastomer network.

 It is essential that the mixture contains both elastomers of the particular type claimed to improve the elastic modulus, and fillers of micronized carbonates to improve the feel and facilitate the homogenization of the elastomeric compounds in the polycaprolactone.

 The mixing of the various compounds is carried out in a dassic manner at room temperature.

 Once the mixture has been produced, this mixture is introduced into the hopper of an extruder heated to a temperature in the region of 900 ° C. (die temperature in the region of 110 ° C.), in order to obtain rods which are cut after cooling to obtain granules which are packaged in bags.

 These granules are extruded in a conventional manner to obtain plates which are conformed to orthopedic splints in a known manner.

 The manner in which the invention can be implemented and the advantages which ensue therefrom will emerge more clearly from the embodiment which follows.

Example:
In a mixer at room temperature, the following are introduced
- one hundred (100) parts of polycaprolactone granules, of molecular weight close to 80,000, marketed by SOLVAY INTEROX under the name "CAPA" registered trademark) 680, having a melting point between 60 and 62cC
- twenty (20) parts of micronized calcium carbonates having an average particle size of three micrometers
- twenty (20) parts of a linear sequenced SEBS elastomer, marketed by SHELL under the brand "KRATON G"
The mixture is then placed in the hopper of a twin-screw extruder heated to 902C and the die of which is heated to 110 C, from which rods of three millimeters (3 mm) in diameter are extruded which are then cooled and then l '' we cut to obtain granules
By means of these granules, plates 0.5 to 5 mm thick, preferably 4 mm thick, are extruded for making orthopedic splints.
These plates are transformed into splints in the usual way by softening in hot water at 60-6SiC, and conformation by the manipulator (surgeon) on the member to be maintained.

 The plates obtained are resistant to creep in temperature, have good elastic return at room temperature, can be shaped after softening for a period of the order of one hundred (100) seconds (three times more than the polycaprolactone plates known at this time. day), and have an ease of remodeling by simple punctual heating, for example by means of a hair dryer to return to the appropriate shape.

 In this way, these plates can be used successfully for making orthopedic splints, or even shoe shape or first.

Claims (5)

RESELL ICATIONS  1 / Mixture for the manufacture of profiled plastic products based on polycaprolactone, characterized in that per hundred parts by weight of polycaprolactone, it also contains  from five to twenty-five (5 to 25) parts of mineral carbonates  micronized,  from five to twenty-five (5 to 25) parts of an elastomer  linear thermoplastic, chosen from the group comprising  styrene-ethylene / butylene-styrene (SEBS) and styrene-butadiene  styrene (SBS).  2 / mixture according to claim 1, characterized in that the micronized carbonate is a calcium carbonate having an average particle size between one and twenty micrometers.  3 / mixture according to claim 2, characterized in that for twenty (20) parts of calcium carbonate, it also contains twenty (20) parts of SEBS.  4 / plastic sheet thickness between 0.5 and 5 mm, produced from the mixture according to one of claims 1 to 3.  5 / orthopedic splint of thickness between one and four millimeters, made from a plate according to claim 4.