CS246336B1 - Thermoplastic mixture for production of heels,heel-wedges and other shoemaker's products - Google Patents

Abstract

The solution relates to the thermoplastic coating blends for making heels, wedges and others footwear products. The material has properties vulcanizate and is processed by the classical technologies for plastics. Its broadest application is in the footwear industry like construction material for the most technical parts.

Description

(54) Thermoplastic compound for the production of heels, wedges and other footwear products

2

The present invention relates to a compound of the thermoplastic composition for the manufacture of heels, wedges and other footwear products. The material has the properties of vulcanizate and is processed by conventional technologies for plastics. Its widest application is in the shoe industry as a construction material for the most technical parts.

The invention relates to a composition of a thermoplastic composition for the manufacture of heels, wedges and other footwear products.

For the production of shoe semi-finished products eg. wedges, heels are used polyolefins, especially polyethylene, polypropylene, or their copolymers with each other or with vinyl acetate. For more demanding applications, when it is necessary to wrap these blanks, the use of impact-resistant polystyrene has been used. This is particularly the case for the known difficulty of gluing polyolefins. For demanding wedge heels which, by their shape, extend to the arched part, this material cannot be used because it is rigid. A certain variation for this use is the modification of standard or tough polystyrene by special types of block thermoelastoplasts. However, their prices are high and the economic reasons put the producers of these semi-finished products in the face of the problem of reducing the content of block copolymers in the mixtures. secondary raw materials.

To match the hardness, toughness and flexibility requirements required of wedges, heels, and other shoe semi-finished products, they are often made from classical vulcanizates. The manufacture of conventional rubber compounds is well known. Each of its technological steps (mixing, shaping, vulcanizing, etc.) is expensive to produce equipment, labor and energy. The cost of vulcanizing rubber is up to 1/5 of the total price of the rubber product.

U.S. Pat. Nos. 3,635,201, 4,046,840 disclose a process for preparing a mixture of rubbers and plastics, which can then be processed by injection molding at elevated temperatures. However, they are materials of low thermal stability caused by the presence of uncrosslinked rubber.

Improvements to the above properties can be achieved by partially cross-linking the rubber in the polymer composition with the plastic already in the preparation of the mixture. It is possible to use the principle of dynamic vulcanization described in U.S. Pat. No. 3,037,954. Partial crosslinking does not yet achieve the maximum mechanical values of the composite.

Clamping dynamic vulcanization requires mixing the rubber and plastic mixture in high speed mixers at 100 οι. per minute and heat 180 ° C in the presence of crosslinking agents. This method of preparing crosslinked rubber and plastic is described in U.S. Patent 1,493,951. Technically applicable materials cannot be obtained by large dynamic vulcanization on large rubber mixing machines with lower rotor speeds. Unprocessed pulp-like products are ignited.

These unfavorable properties do not overload the shoe material consisting of impact-resistant polystyrene, block styrene-butadiene thermoplastic rubber and ground vulcanizate particles of natural rubber or butadiene-styrene rubber. However, it remains a disadvantage of the fact that the coating of the semi-finished product after application of the polychloroprene adhesive results in a strong swelling of its surface and deformations on the edge of the article.

The present invention is a thermoplastic blend for the manufacture of heels, wedges and other footwear products, characterized in that it comprises 15 to 80% by weight of polyolefin, olefin copolymer or a mixture of 5 to 60% by weight of ground vulcanizate particles of natural or butanedienstyrene rubber; mixtures thereof whose average size is 0.5 to 3 mm. In an alternative embodiment, the material consists in addition of 0.5 to 25% by weight of block butadiene styrene or styrene-isoprene thermoelastoplast.

The thermoplastic composition for the production of heels, wedges and other shoe products according to the invention has the following advantages:

It represents a new generation of polymer composites vulcanizates - plastic processed by plastic technology, but finally has the properties of thermcset rubbers. The cross-linked rubber particles are dispersed in a continuous thermoplastic matrix.

The thermoplastic composition of the present invention contributes significantly to the treatment of the rubber waste from which the milled vulcanizate particles are prepared. The use of secondary rubber raw materials, which are present in sufficient quantities directly in the shoe factories, also solves ecological problems. The use of this thermoplastic composition also entails considerable energy savings, as the process of partial or clamped dynamic vulcanization of heated rubber agitators is eliminated.

Evidently improved physico-mechanical values are obtained when thermoplastic rubber of the styrene-butadiene-styrene configuration is added to the polyolefin-vulcanizate blend, which is explained by improved phase-interface parameters.

The thermoplastic composition for the production of heels, wedges and other shoemaking articles is prepared and processed in a substantially court-like manner, either continuously or directly through the so-called " dry blends.

In a discontinuous manner, the individual recipe components are heated to 140-180 ° C in a closed mixer whose chamber is heated. From it, the material passes to a two-roll calender heated to 110-150 ° C. The strip of material is stretched from the calender by an extruder equipped with a granulating head. The extruder has a temperature of 130-160 ° C and a granulation head of 130-150 degrees Celsius. The pellets of the material after passing through the pelletizer are placed in collecting tanks.

When processing directly through the so-called. The dry blends are homogenized in the tumbler mixer by the individual components of the recipe: polyolefin or its copolymer, or alternatively the blend is supplemented with block butadiene styrene rubber and this blend is directly filled into the injection molding hopper. It is processed into heels or wedges at temperatures of 150-170 ° C.

To illustrate the invention in greater detail, several embodiments are described in which the application of the thermoplastic composition of the invention to heels and wedges and some of its physical and mechanical properties are described.

Example 1

The shoe material intended for wedge production also consists of a branched type high-pressure polyethylene with a melt index of 10 50 wt. %

b) Ground natural rubber vulcanizate with a grain size of 0.1 mm 50 wt. %

The material was treated in the above-described continuous manner and test bodies were prepared from the granulate by injection molding. Their physical-mechanical properties are as follows:

Taonine Flow Index, g / 10 min.,

180 ° C, 5 kg

ShA hardness

Strength, MPa

Ductility,%

Abrasion resistance,%

Specific gravity, g / cm ³

Example 2

6.1

120

1,056, also Polypropylene of melt index

Θ0 wt. ^c / o

b) Butadiene-styrene rubber vulcanizate having a grain size of 0.2 mm 30 wt. % Siylene-butadiene rubber block containing styrene-butadiene 35-65 10 wt. %

The material was treated with the dry blends technique described above. The prepared test specimens showed the following values:

Melt Flow Index, g / 10 min.,

180 ^° C, 5 kg 1.8

SHA 98 hardness

Strength, MPa 15.6

Ductility,% 50

Abrasion resistance,% 155

Specific Gravity, g / cm ³ 1,024

Example 3

The thermoplastic composition for the production of wedge heels consists

a) Ethylene vinyl acetate copolymer containing 15% vinyl acetate, melt index 12 60 wt. %

b) Ground wastes from butadiene styrene vulcanizate 35 wt. % cj Thermoplastic rubber, styrene-butadiene - 35-65 5 wt. %

The dry blends treated material exhibited the following physical values:

Melt Flow Index, g / 10 min., 180 ° C, 5 kg 3.5 Hardness, Sha 96 Strength, MPa 8 Ductility% 48 Abrasion resistance,% 112 Specific gravity, g / cm ₃ 1,060

The thermoplastic composition for the production of thermoplastic heels consists

Claims (2)

SUBJECT Thermoplastic composition for the manufacture of heels, wedges and other footwear products, characterized in that it contains 15 to 80% by weight of polyolefin, olefin copolymer or a mixture thereof, 5 to 60% by weight of ground vulcanizate particles of natural or butadiene styrene OF THE INVENTION Rubber or mixtures thereof having an average size of 0.5 to 3 mm. 2. A thermoplastic composition according to claim 1 comprising from 0.5 to 25% by weight of block butadiene styrene or styrene isoprene thermoelastoplast.