CS231388B1 - Shoe sole material - Google Patents

Abstract

The invention relates to thermoplastic elastomer material for the production of shoe soles. The purpose of the invention is to reduce the cost of preparing the sole material by replacing part of the original S-B-S elastomer with secondary raw materials, without, of course, worsening the physical-mechanical properties of the resulting soles. This purpose is achieved by the fact that, according to the invention, the shoe sole material mixture contains, in relation to the total weight of the basic polymers, 5 to 30 percent by weight of filler particles in the shape of spherical bodies and a diameter of 0.2 to 1.7 mm from rubber made from butadiene styrene rubber, in which the proportion of the styrene component is 40 to 50 percent by weight and containing 15 to 30 percent by weight of ground silicon dioxide.

Description

This invention provides a shoe sole material based on 80 - 100 parts by weight of a block copolymer of the Ax-Ey-Ax type, in which Ax forms polystyrene blocks with an average molecular weight of 20,000 to 30,000 and their share in the total copolymer is 30 to 40 percent by weight, while By forms polybutadiene blocks with an average molecular weight of 35,000 to 150,000, whereby these basic polystyrene and polybutadiene block units are arranged non-linearly with each other by crossing into spatial teleblocks with a possible substitution of a maximum of 30 to 36 percent by weight of linearly arranged block copolymers, 10 to 50 parts by weight of crystalline polystyrene thermoplastic with a molecular weight of 180,000 to 220,000, 10 to 35 parts by weight of an extender, predominantly naphthenic oil, and further fillers, optionally coumarone resin, ethylene-vinyl acetate copolymers and/or blowing agents.

In recent years, block copolymers have been used industrially; among them, in particular, the polystyrene-polyisoprene-polystyrene and polystyrene-polybutadiene-polystyrene types. If they are produced in a relatively limited range of molecular weights, these block copolymers exhibit elastomeric properties without the need for vulcanization and at the same time exhibit processing capability in thermoplastic machinery from temperatures exceeding their softening point. These processing methods include, in particular, extrusion or injection molding, and it is also worth noting that they can be processed repeatedly in this way, which means that they do not create waste that would have to be regenerated before reprocessing,

With regard to the favorable flow properties of block copolymers, they are used for more demanding footwear applications, such as unitary soles with heels for men's and especially women's shoes, where the wall thickness and total heel height play a significant role, although they sometimes showed heel collapse under load, probably due to the linear arrangement of the block polystyrene, s231 388

- 2 that is countered by the possible further addition of filling crystalline polystyrene.

Apart from a small proportion of polystyrene, which perhaps fits into the so-called polystyrene domains of the basic block copolymer, the main part of the polystyrene forms a reinforcement, which could be called a polystyrene skeleton. This part then most significantly influences the physical and mechanical properties in a positive sense, especially the hardness of the manufactured soles and heels and their resistance to abrasion. However, the spatial teleblocks of block copolymers do not exclude the possibility of confusion with linearly arranged block copolymers, if their proportion does not exceed a maximum of 30 to 35 percent by weight.

However, it must be admitted that the prices of basic block copolymers are high and that economic reasons present manufacturers of sole materials with the problem of reducing the content of these copolymers in mixtures, which is generally solved by using so-called secondary raw materials. From a general perspective, this usually results in a deterioration of the physical properties of the sole material, which is not at all desirable from the point of view of technical progress.

These unfavorable properties do not affect the shoe sole material based on 80-100 parts by weight of a block copolymer of the Ax-Jty-Ax type, in which Ax forms polystyrene blocks with an average molecular weight of 20,000 to 30,000 and their share in the total copolymer is 30 to 40 percent by weight, while Ety forms polybutadiene blocks with an average molecular weight of 35,000 to 150,000, whereby these basic polystyrene and polybutadiene block units are arranged non-linearly with each other by crossing into spatial teleblocks with a possible replacement of a maximum of 30 to 35 percent by weight of linearly arranged block copolymers, 10 to 50 parts by weight of crystalline polystyrene thermoplastic with a molecular weight of 180,000 to 220,000, 10 to 35 parts by weight of extender, mainly naphthenic oil and further fillers, optionally coumarone resin, ethylene vinyl acetate copolymer and/or blowing agent, the essence of which according to the invention consists in containing, based on the total weight of the basic polymers, 5 to 30 weight percent of filler particles in the form of spherical bodies with a diameter of 0.2 to 1.7 mm made of rubber, made of butadiene-styrene rubber, in which the proportion of the styrene component is 40 to 50 weight percent and containing 15 to 20 weight percent of ground silica.

In the shoe sole material according to the invention, the proje231 388

- 3 have the following advantages: first of all, the abrasion resistance remains in the range of 80 to 82%, while the rebound elasticity even increases slightly from the original 40% to 44%, which increases the resistance of the sole against the penetration of foreign bodies, i.e. sand and stones when wearing shoes. The hardness remains in the range of 60 to 65 ShA. In addition, the shoe sole material according to the invention contributes significantly to solving ecological problems by using secondary raw materials, i.e. rubber flour with precisely defined parameters.

The shoe sole material according to the invention is prepared and processed in essentially two ways, namely continuously or discontinuously. In the continuous method, the individual components are homogenized in a kneader, for example with a capacity of 140 liters, the chamber of which is heated to about 130 °C, from where the material passes to a two-roll calender, with rolls heated to a temperature of 90 to 100 °C. From here, the material strip is transported to a granulation device, which consists of an extruder with a roll temperature of 90 to 100 °C and a granulation head with a temperature of 85 to 95 °C. From here, the granules pass to a cooling device and to packaging.

In discontinuous production, the individual components of the material are homogenized in a kneader and then transferred to a two-roll calender, with possible processing also on a three-roll calender, from which the material in the form of a strip then proceeds to a multi-level belt cooler to the cutting device. In the next process, the strips of material come to a heating calender with a temperature of 90 °C and to an extrusion piston machine, for example of the Homrich type, whose nozzle is adapted to extrude rods with a diameter of 4 mm and the arm is adapted to carry the cutting knives. This is followed again by a device for cooling the granules and packaging the material, for example in bags.

For both processes, the homogenization of the components is carried out in two phases.

In the first phase, the S-B-S teleblock copolymer is homogenized in the kneading chamber with crystalline polystyrene, or with high-styrene resin or high-styrene rubber. In this phase, the appropriate proportion of filler particles in the form of spherical bodies with a diameter of 0.2 to 1.7 mm made of rubber, made of butadiene-styrene rubber, in which the proportion of the styrene component is 40 to 50 weight percent and containing 15 to 20 weight percent of ground silica, i.e. the so-called rubber flour, which is a term used in some places in the description for simplicity. The temperature of these components during mixing is 231 388

- 4 is heated to 150 °C. An antioxidant, an ultraviolet radiation absorber and, if applicable, a stabilizer are added to them. The total homogenization time is 2 to 5 minutes. After the end of the first mixing phase, the heating of the mixing device is interrupted in both processes, especially because a blowing agent is added to the lightweight sole material at the end of the mixing, so that if the temperature of the shoe sole material mixture according to the invention exceeds 160 °C, its decomposition would occur.

^r ' In the second stage of mixing, pigments, fillers and oil are added to the material mixture. The addition of oil to the mixture of components of the shoe sole material according to the invention is gradual, preferably with simultaneous addition of the filler, taking into account the high weight fraction of oil. The low-solidifying oil used is characterized by low evaporation at higher mixing temperatures and when processed in extruders.

The filler, especially based on silica, the total content of which is reduced compared to conventional processes, used in the shoe sole material according to the invention, binds oil with its large surface area during mixing and thus significantly shortens the mixing process. In addition to silica fillers, combinations based on silica and calcium carbonate are used, for example, for compact sole mixtures.

Several exemplary embodiments will serve to further clarify the invention, which also describe the industrial application of the sole material according to the invention in the shoe industry and some of its physical and mechanical properties.

Example 1

Footwear material intended for the production of colored unit soles and the production of soles by direct injection.

S-B-S Teleblock Copolymer (bu:sty=60:40; set 50 dsp oil) 85 mass parts S-B-S teleblock copolymer (bu:sty=7O:3O) 15 »1 H Ethylene vinyl acetate copolymer 1 H ¹ n Crystalline polystyrene, clear 30 H tt •'Rubber flour No.8O 15 1» <1

(spherical bodies with a diameter of 0.2 to 1.7 mm made of butadiene-styrene rubber; bu-sty=5O-6O:40-50+15 to 20 weight percent ground silica)

Antioxidant mercaptobenzthiazole 0.8

Stabilizer dilauryl dithiopropionate 0.7

TPE dye white 5

- 5,231,388

Blowing agent azodicarbonamide 0.3 parts by weight Extract resin 1 M Zinc oxide 1 II II Stearin III 0.6 tt Titanium dioxide 0.4 II ♦1 Low-solids oil OLN-4 32 II VI

Soles made by replasticization of granulate from this material exhibited the following physical-mechanical properties:

Melt flow index, g/10 min, 180 °C, 5 cp 4

Density, g/cm? 0.98

Hardness °ShA 69 ' Rebound elasticity, % (Schob method) 55

Elongation, % 560 ’ Resistance to cracking (Matthias method) 100,000 bends

Abrasion resistance (Bussen-Schlobach method), % 75

Example 2

Single lightweight soles were prepared from several mixtures in which the content of individual components varied as follows:

Teleblock copolymer S-B-S (bu-sty=60:40+50 dsp oil)

Crystalline polystyrene clear

Ethylene vinyl acetate copolymer (VAC content = 5-25 wt. percent)

Low-viscosity naphthenic oil

Kumarone light, solid

Phenolic antioxidant

UV absorber (benzothiazole derivative)

Silicon dioxide

Dyes

Azodicarbonamide blowing agent ‘'Rubber flour

Zinc oxide

90-100 parts by weight

20-30

1-6

20-30

1- 5 0.5

0.5” “

2- 5

0.5-5 0.3-1

10-25 0, 5-1

Example 3

The composition of several batches of shoe sole material for compact unit soles and for direct injection soles, molded in black or a dark shade, varied in the range:

Teleblock copolymer S-B-S 76 parts by weight (bu-sty=60:40+50 dsp oil)

- 6,231,388

Teleblock copolymer S-B-S 10 parts by weight (bu-sty= 70:30)

rubber flour mill no.60 5-30 ♦t ff Crystalline polystyrene, clear 20-30 fl lt Ethylene vinyl acetate copolymer (VAC content = 5-25 parts by weight) 1-5 H fl Extract resin 1-3 f| fl Stabilizer dilauryl dithiopropionate 0.4-0.6 those tt Phenolic antioxidant 0.4-0.8 those tt Zinc oxide 0.5-1 tf tt TPE barrel carbon black P-1250 10-12 11 tl Stearin III 0.3-0.6 tl lt TRIUMF Aromatic Softener 10-30 tt tl The soles of this material showed these physically mechanical features : “3 Density, g/cm 0.98 Hardness, °SHA 60-70 Strength, MPa 6-7 Elongation, % . 550-650 Abrasion resistance, % 75-80 Resistance to cracking 100,000 bends

Melt flow index (g/10 min), 180 °C, 5 kg 2 Example 4

A shoe sole mixture containing 9 percent rubber flour by weight contained the following components in parts by weight:

Solpren 475 90,000 parts by weight Solpren 416 15 000 lt tt Krasten 127 G 32 000 tt tt Miravite D-23 1 500 tt tt Rubber flour No.80 18 000 tt tt Chemantox 500 tt tt Antioxidant MB-3 900 tt tt Stearin III 600 tt tt Zinc oxide G 1 000 tt tf Cumarone resin, dark 2 000 w tt TPE barrel 698 5 000 tt tt Titanium white 400 lt tl Asphalt A0K-120 150 tt tt Azoplaston 300 tt tt

231,388

- 7 Oil OLH-4

Silicon dioxide

Physical-mechanical parameters

Hardness I.E.H.D *s

Density, g/m3

Abrasion resistance, %

Modulus 100%, MPa Strength, N Strength, MPa Elongation, %

Tear strength, N/mm Breakage, kc Rebound elasticity

000 weight d. 8 250 *

0.98

2.0

115.4

6.8

600

25.5 100,000

Claims (1)

SUBJECT OF THE INVENTION 231 38B The shoe sole material based on 80-100 parts by weight of an Ax-Ey-Ax block copolymer in which it forms polystyrene blocks with an average molecular weight of 20,000 to 30,000 and their proportion in the total copolymer is 30 to 40% by weight, while E They form polybutadiene blocks having an average molecular weight of 35,000 to 150,000, the basic polystyrene and polybutadiene block units being non-linearly interconnected with each other by intersecting them into space teleblocks, possibly replacing a maximum of 30-35% by weight of linearly arranged block copolymers, 10 to 50 parts by weight of crystalline polystyrene thermoplastic having a molecular weight of 180,000 to 220,000, 10 to 35 parts by weight of extender, predominantly naphthenic oil, and also fillers, possibly coumarone resins, ethylene vinyl acetate copolymer and / or blowing agents, by containing, based on the total weight of the base polymers, 5 to 30 weight percent of spherical body-shaped filler particles having a diameter of 0.2 to 1.7 mm of rubber made of butadiene-styrene rubber in which the proportion of styrene component is 40 to 50 % by weight and containing 15 to 20% by weight of ground silica.