HU210201B - Procedure for making of sole insert material - Google Patents

Abstract

The prod. comprises (%) 20-100 natural rubber or synthetic polypropylene and 0.5-35 fillers, softener, plastic mesh, moisturiser and other additives that are mixed and heated to 100 deg.C under Defo-pressure of 110-60 deg. The moisturiser/vulcaniser ratio is such that the evaporation rate of the moisturiser speeds up the vulcanisation.

Description

FIELD OF THE INVENTION The present invention relates to a process for producing an insole with improved properties. By "improved property" is meant increased elasticity, increased fatigue and aging resistance compared to prior art types, and that the energy required for production is significantly (20-30%) lower than known processes.

The ever-increasing quality and health demands require an increased effort from the footwear industry to ensure that their products provide adequate wearing comfort in every respect. Regardless of fashion and quality level, the orthopedic correct placement of the foot and ensuring proper wearing comfort becomes one of the decisive criteria for usability. This is the purpose of the various pads in different parts of the footwear. so e.g. Brötje Gummi und Kunstsoffabrik GmbH is a so-called A "heel cushion" to provide walking flexibility He recommends a "heel cushion" to prevent the heel from slipping out and to protect the back of the heel and the ankle. Emsold GmbH insoles for closed shoes protect against ankle sagging, foot spreading and protrusion. In the case of safety footwear, the wearing comfort can be significantly improved by the use of "onrush pads" against steel toe straps. Their use avoids various pressure points. It is engaged in the production of inserts for such purposes eg. the gene is Helmers GmbH.

The "ankle" and the "tongue paws" are responsible for protecting the foot and ankle parts from impact. Hard skin also requires this protection. These types are mainly found in ski and other sports shoes. The footbed inserts (“the fiberglass”) in sandals and open-toed sandals provide the perfect fit of the foot. Variants are made with or without leg and ankle support.

In all cases, the simultaneous requirements that are highlighted for use are: adequate elasticity (which can be inferred from the measurement of dynamic properties, such as rebound elasticity), minimal residual deformation under compression, fatigue resistance, and properties should change as a function of time, ie as little as possible during aging and storage.

These and similarly known products for similar purposes are made almost exclusively of synthetic or natural latex and, to a lesser extent, of PVC, polyurethane or polyethylene. ethylene / vinyl acetate copolymer; and crosslinked polyethylene.

Natural and synthetic latex and combinations of these in various proportions have long been used in the manufacture of lightweight, low-density foam products. There are several different methods of making latex foam. A common feature is that all of their sub-processes are very energy intensive and have a very long production cycle.

The largest quantities are manufactured by the Dunlop method, in which the latex mixture is mechanically foamed (Cook, P. G., Latex Natural and Synthetic. London, 1956). Mechanical foaming is also used in the production of Telaley's foam rubber (Bayer Ag. Handbuch für die Gummi-Industrie, Stuttgart, 1971). While the common feature of these processes is that the foaming is carried out mechanically, In the Revertex method, foaming is achieved by a chemical reaction (Revertex Ltd .: Revultex Prevulcanized Ltd., 1967). Although relatively simple and undemanding, this process is not widespread on an industrial scale because the process is chemically difficult to control due to enzymatic foaming. The products obtained have good physical characteristics, but are very high due to the high energy demand, the difficult chemical process and the complexity and complexity of the operations. A further disadvantage is that the favorable wearability properties of natural latex-based products are significantly reduced during wear and storage.

They do not play a major role in the various sheets and foamed products made of polyethylene and ethylene / vinyl acetate copolymer, generally cured. Their advantage is their very low density (0.1-0.2 g / cm ³ ) and the resulting relatively low commodities; their disadvantage is that they have little flexibility. Therefore, in applications subject to a high degree of dynamic compression, such as: insoles, comfort pads, pads - practically do not match. A further disadvantage is that they have very low moisture absorption and water vapor permeability. Although this can be helped to some extent, for example by: Fiber material is provided on the surface and the inside of the insert, such as the one described in U.S. Pat. However, this solution can only partially overcome these disadvantages.

Lightweight, low density (0.5 g / cm ³ ) porous structure pads can also be made of PVC plasticisol. The plastisol may be foamed by mechanical or chemical means. The mechanical method is more well known and more common. They are made with Eur-U-Matic foaming equipment. The air-foamed plastisol solution exiting the device drain pipe is conducted in a cold form and then gelled at 170 ° C for 20-25 minutes after filling the tool. Since this method practically does not involve foam deposition, the cooled, molded product perfectly reproduces the shape of the tool. The quality of the product produced by this method is satisfactory, but due to the complex manufacturing technology and high energy consumption (tool heating, cooling), production is not very economical and therefore not widespread.

It is also possible to make comfort pads from conventional binary polyurethane (polyester and polyether based) polyurethanes by the known polyurethane molding or molding process. with injection molding equipment. However, the production of polyurethane-based comfort pads does not play a significant role due to its very high raw material, on the one hand, and its inefficient production method, and, on the other, its unfavorable aging and fatigue resistance.

HU 210 201 Β

Also known are insoles of various industrial wastes (eg cork, perlite, vulcanized rubber, soft polyurethane foam): Hungarian patent specification; of elastomer (polyurethane, butyl rubber, polyethylene, ethylene / vinyl acetate), containing cells filled with gas (eg hexafluoroethane, sulfur hexafluoride, perfluoropropane, etc.): 2,801,197 German Patent Specification; and many other materials (tanned leather, imitation leather, etc.): No. 2,852,894. German Federal Publication Document.

A known method for making lightweight, low-density products from blends of rubber based blends is the conventional rubber technology. The preparation of porous products, formulations and usable mixtures are described in detail in Part II of the Rubber Industry Manual. (Taurus-OMIKK, Budapest, 1989, pp. 854-857). However, this technology is not suitable for the production of precision molded bodies.

Summarizing the state of the art, there is currently no known recipe and technology for the production of an insole that results in a product that has improved fatigue resistance, less permanent deformation and greater elasticity, and has favorable storage, wear and tear properties. do not change.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and a formulation for eliminating existing and known defects, by which an insole material having greater elasticity, fatigue resistance, and less deformation under pressure than known insole materials can be produced.

It is another object of the present invention to ensure that said properties of the insole materials produced by the process do not change significantly during aging (storage, wear).

It was a further object of the invention that the production of improved insoles be accomplished by a process that requires less energy than before.

Finally, it is a further object of the present invention to provide improved insole inserts that are easy to manufacture in equipment used in the rubber industry.

The present invention is based on the surprising discovery that the above object can be achieved by using a mixture of materials which, in addition to the rubber and the additives known per se, contain a blowing agent / vulcaniser combination at which the blowing agent decomposes at the temperature of vulcanization. ) is greater than the rate of the vulcanization reaction, but the amount of blowing agent exceeds that of the crosslinking agent.

Thus, the present invention is a process for the production of an improved insole at 100 ° C with a defo hardness of 100 to 400 parts by weight of natural rubber or synthetic polyisoprene, 0.5 to 350 parts by weight known per se, plasticizer, vulcanizer, blowing agent, dye and other conventional by use of adjuvants and additives and one or more members thereof, by plasticizing and vulcanizing the mixture, which means that the amount of volatilization agent is preferably in the range of 1.2 to 8 times the rate of decomposition (evaporation) at the respective vulcanization temperature. velocity blowing agent is used and the mixture is plasticized in a manner known per se at 50110 ° C under shear and pressure, while the Defo hardness of the mixture measured at 100 ° C is 110600 and then at 120-200 ° C the internal pressure in the mold cavity not more than 0.1 MPa-l and c.

In a preferred embodiment of the process, the vulcanizing agent is sulfur and the blowing agent is 1.2 times the amount of Ν, Ν-dinitrosopentamethylene tetramine.

In another preferred embodiment of the process, 1.3 times azo-diisobutyronitrile is used as a vulcanizing agent and as a blowing agent.

In another preferred embodiment of the process, dicumyl peroxide is used as a vulcanizing agent and 8 times the amount of p, p'-oxybis (benzenesulfonylhydrazide) as blowing agent.

Natural and synthetic polyisoprenes are preferably used as the rubber component. Commercially available types are described e.g. Rubber World Blue Bokk, 1989 Edition, Materials and Compound Ingredients for Rubbers; Natural Rubber, p. 389-394. Polyisoprenes p. 430-444.

As a cross-linking agent, sulfur or sulfur. dicumyl peroxide is used.

The blowing agent used is N, N'-dinitrosopentamethylene-tetramine, azo-diisobutyronitrile or p, p'-oxybis (benzenesulfonylhydrazide).

The composition is made using additives well known in the rubber blending technology. Other commonly used blend components are fillers and enhancers (aromatic, naphthenic or paraffin oils, extender oils), stabilizers, antidegradants, dyes, various activators, accelerators. For a detailed description of their chemical nature and commercially available types, see Rubber World Magazine's Blue Book of Materials, Compounding, Ingredients and Machinery for Rubber, 1990. Edition: Lippincolt and Pet.

Conventional rubber mixers are suitable for preparing the composition.

The invention is further illustrated by the following non-limiting examples.

example

Manufacture of insoles suitable for heel pads.

The mixture of Table 1 was prepared on a 600x250 mm laboratory roll.

Table 1

Composition of insole for heel pads

Identification of components Quantity of components for 100 parts by weight of rubber Natural caoutchouc * 100.0 Stearin 2.0 2,2-Dibenzo-tiazil-disulphate fid ** 1.0

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Identification of components Quantity of components for 100 parts by weight of rubber Tetramethyl thiuram disulphate fid *** 0.2 Zinc oxide **** 10.0 salicylic Acid 1.0 N, N'-pentamethylene dinitroso tetramin ***** 3.0 Sulfur 2.5

* SMR-10 Malaysian products (hardness 400 Defo) ** Altax (Vulkacit DM), Bayer AG product *** Thiuram M, Monsanto product **** Red seal (grain size 800-1000 μιη; bulk density 900 g / l) * **** Lhempor PC-80, Czechoslovakian product, decomposition temperature: 120 ° C, specific gas formation: 260 cm ³ / g.

In the first production step, natural rubber was crushed to a plasticity of 400 Defo hardness.

The temperature at the start of the fracture was 40 ° C, which was raised to 70 ° C after a 30 minute fracture. At the end of the second fracture, also for 30 minutes, the roller temperature was 60 ° C.

In the second step, the mixture of Table 1 was prepared, also on a rolling mill.

Time course of mixing:

minutes of 2xbroken natural rubber sheathing

0-3 minutes to heat the rubber

4-5 minutes add activators, accelerators

6-10 minutes fillers, salicylic acid addition 11-12 minutes blowing agent

13-14 minutes sulfur injection

15-16 minutes homogenization

Extrusion: Thickness at least mm greater than the vulcanizing die. The plasticity of the mixture at the end of mixing is 410 Defo hardness. After 24 hours of mixing, it was vulcanized. The mold casting was 50%.

The vulcanization rate was determined using a VUREMO (manufactured by the National Rubber Company) and the foaming rate was measured using a Brabender Plasti Corder measuring instrument. The measurement results are shown in Figure 1:

"Variation of time of curing and foaming as a function of temperature."

In the figure, the abscissa: temperature (° C) ordinate: time (min) curve: crosslinking curve: foaming.

From the figure it can be seen that at 150 ° C the rate of foaming is higher than the rate of vulcanization. (Similar results were obtained for the blowing agents / vulcanizers used in Example 2.)

The vulcanization was carried out in a steam heated etage press. The vulcanization parameters are:

pressure 0.4 MPa temperature 150 ° C vulcanization time 7 minutes

The weighing (form filling) was done so that the complete filling of the form was ensured.

The resulting vulcanizate (heel cushion) has a non-blistering, deformation-free surface.

Among the physical parameters of the product, the following properties determining the usability were investigated: tensile strength, elongation at break, tensile strength, product properties under dynamic stress (measurement of rebound elasticity by Schob method), residual deformation (under compressive stress), and dynamic fatigue change. The test results are shown in the Summary Table (Mixture 1). The data in the table illustrates that the product of the process ("1") is practically the same as in the comparative example mixture (3a-3d) in terms of tensile strength, tensile strength and elongation at break, but the residual deformation of the product under dynamic conditions , fatigue, and their change with aging, is more favorable than latex-based products for similar purposes. No subsequent shrinkage was observed.

Example 2

Suitable for insole use. preparation of comparative (foaming agent / vulcanizing agent ratio less than 1) insole material

The mixtures according to Table 2 were prepared in a 120 liter Commario internal mixer. The rotors were rotated at 45 rpm.

In the first step of the mixing, the rubber component was softened in a closed mixer by adding 0.2 parts by weight of the pentachlorothiophenol zinc salt (Renacit 4) to the disintegrator. At the end of softening, 815 minutes of mixing time) the plasticity of the rubber component is 120 Defo hardness.

In the second step, the mixtures of Table 2 were prepared, also in an internal mixer.

Time course of mixing:

minutes of 2xbroken natural rubber sheathing

0-3 minutes to heat the rubber

4-5 minutes add activators, accelerators

6-10 minutes additions of fillers, delays

Addition of blowing agent for 11-12 minutes

13-16 minutes, lowering the mixture to the roll, adding the curing agent

Extrusion: at least 2 mm thicker than the vulcanizing die. The fill rate is 40%.

The vulcanization was carried out in a steam heated etage press. The vulcanization parameters are:

pressure: 0.6 MPa temperature: 160 ° C vulcanization time: 9 minutes.

Weighing was done with the material completely filling the mold.

For the mixtures 2a, 2b, 2c according to Table 2, the resulting vulcanizate has no blistering surface, is completely filled in, and has a uniform structure.

The physical indicators described in Example 1 were examined. THE

EN 210 201 Β test results are given in the Summary Table. It can be seen that the dynamic properties of the products (2a, 2b, 2c), the residual deformation of these products and the development of these properties during aging tests are more favorable than those of 2d and 2c. 2e and natural or synthetic latex based products for similar purposes. In addition, 2d and 2d respectively. In the products of Comparative Examples 2e (i.e., where the weight ratio of blowing agent / vulcanizer is less than 1), a significant amount (10% or 14% by weight) or less, respectively. irregular, unpredictable post shrinkage was observed. This is disadvantageous for orthopedic application because it prevents the dimensionally accurate formation of the spatial insole.

Table 2

Suitable for insole use (2a, 2b, 2c), respectively. composition of a comparative (2d, 2e) insole

Identification of components Quantity of components for 100 parts by weight of rubber 2a 2b 2c 2d 2e Natural rubber ¹ 100.0 - 100.0 100.0 100.0 1,4-cis-polyisoprene ² - 100.0 - - - 2,2-Dibenzothiazolyl disulfide ³ (accelerator) 1.0 - - 1.0 1.0 N-Morphoni 1-2-benzothiazole sulfenamide ⁴ (accelerator) - 1.0 - - - Tetramethylthiuram disulfide ⁵ (accelerator) 0.2 0.3 - 0.2 0.2 Ν, Ν'-Dinitrosopentamethylene tetramine ⁶ (blowing agent) 3.0 - - 2.0 1.3 Azo-diisobutyronitrile ⁷ (blowing agent) - 4.0 - - - P, P'-oxybis (benzenesulfonyl hydrazide) ⁸ (blowing agent) - - 8.0 - - Sulfur (vulcanising agent) 2.5 3.0 - 2.5 2.5 Dicumyl peroxide ⁹ (vulcanising agent) - - 1.0 - - Triallyl cyanurate ¹⁰ (activator) - - 0.1 - - Zinc oxide (activator) 10.0 15.0 - 10.0 10.0 Stearic acid (activator) 2.0 2.0 - 2.0 2.0 Salicylic acid (retarder) 1.0 1.0 - 1.0 1.0 Kaolin (filler) 50.0 100.0 20.0 50.0 50.0 Paraffin (Softener) - 10.0 10.0 - - Spindle oil (plasticizer) 15.0 - 10.0 15.0 15.0 Instrument oil (plasticizer) - 20.0 - - -

Identification of components Quantity of components for 100 parts by weight of rubber 2a 2b 2c 2d 2e Carbonated lime (filler) - - 150.0 - - Vanillin (fragrance) 0.5 0.5 - 0.5 0.5 Renacit4 ⁿ (breakdown agent) 0.2 0.2 0.2 - 0.2

'SMR 20 Malaysia ² Coriflex IR-305 (Shell) ³ Example 1 ⁴ Santacure MOOr (Monsanto) ⁵ Example 1 ⁶ Example 1 ⁷ Genitron AZDN (FBC Industria Chemicals) ⁸ Porofor TSH Powder (Bayer AG) ⁹ Di-Cum (Akzo Chem.) ¹⁰ TACIS (Akzo Chem.) ¹¹ Vanderbilt

Example 3

Comparative mixtures illustrating the state of the art

The samples used for comparison were made using the methods described in the prior art on the basis of natural or synthetic latex. Natural latex 3a, "Telaloy" based on synthetic latex 3b, "Revertex" from 3c natural and synthetic latex, and 3d, also known as "Dunlop" polychloroprene latex. The mixture compositions are shown in Table 3 and the test results for the samples are summarized in Table 3.

Table 3

3a: Natural latex based foam rubber composition

Blend ingredients Dry matter content by weight Quantity, parts by weight Natural latex (modified with ammonia) 60 167.0 Ammonium carbonate 10 2.0 Potassium oleate 20 2.5 Potassium ricinoleate soap 33 2.25 Sulfur 50 5.0 Zinc dietilditiokarba- Matthew 50 2.0 Zinc mercapto-benzti- azole - 1.5 PBNA 50 1.0 Diphenyl guanidine 30 0.6 Ammonium chloride 20 1.0 Zinc Oxide 50 0 Na (silico fluoride) 20 5.0

HU 210 201 Β

3b: Synthetic latex based foam composition

Blend ingredients Dry matter content by weight Quantity, more-. megrósz Butadiene-styrene latex (Polysar latex 723) 65 154 Potassium oleate 20 4.5 Sulfur 50 4.5 Zinc diethyl ditiokarba- Matthew 50 1.5 Zinc mercapto-benzti- azole 50 2.0 Antioxidant 2246 50 2.0 Kaolin 67 15.0 Nail 33 15.0 Vulcafor EFA 50 2.0 Zinc Oxide 50 10.0 Na (silico fluoride) 20 12.5

3c: latex and natural latex based foam rubber composition

Mixture of ingredients Dry matter content by weight Quantity, parts by weight Butadiene-styrene latex (Pliolite latex 5352) 69 77 Natural latex (preserved with ammonia) 60 83 Potassium oleate 20 2.5 Sulfur 50 4.5

Mixture of ingredients Dry matter content by weight Quantity, parts by weight Zinc diethyl ditiokarba- Matthew 50 1.5 Zinc mercapto-benzti- azole 50 1.5 Antioxidant 2246 50 2.0 Kaolin 67 15.0 Vulcofor EPA 0.3 1.0 Zinc Oxide 50 10.0 Na (silico fluoride) 20 10.0

3d: Polychloroprene latex based foam rubber composition

Blend ingredients Dry matter content by weight Quantity, parts by weight Polychloroprene latex (Neoprene latex 60) 50 169.5 Zinc Oxide 50 15.0 Sulfur 50 4.0 P, p'-dibenzoyl quinone dioxime 50 4.0 Antioxidant 2246 50 4.0 catechol 50 2.0 Na dibutyl ditiokarba- Matthew 25 4.0 foam Stabilizers 15 0.67 Na (silico fluoride) 20 10.0

Summary Table

Physical index tested Mixture sign 1 2 / 2 / b 2 / c 2 / d 2 / e 3 / a 3 / b 3 / c 3 / d Tensile strength, N / mm ² 2.5 1.5 1.2 1.0 0.7 2.9 1.8 1.1 1.0 1.7 % Elongation at break 425 300 216 185 105 180 230 180 175 210 Fracture resistance DIN 53 515, ASTM D 624, ISO 34) 15.2 10.7 8.1 7.3 5.1 16.2 11.5 10.2 10.8 12.3 Density (g / cm ³ ) 0.35 0.40 0.45 0.48 0.8 0.92 0.40 0.45 0.46 0.42 Bounce Elasticity with the Schob Method (MSZ 11 078; ISO 4662; DIN 53 512) 26 21 17 14 12 25 15 17 16 15 Permanent deformation,% 6.1 9.7 11.3 13.5 25.5 26.9 8.5 9.3 9.1 8.8 Fatigue test with dynamic fold resistance test (De Mattia 30 ke) (ASTM D623; DIN 53 533; ISO 4666) n. s. n. s. n. s. n. s. n. s. n. s. n. s. n. s. n. s. n. s. Aging resistance test [change in fatigue under natural weather conditions (during wear) - 1 month wear (8 hours / day)] n. s. n. s. n. s. n. s. n. s. n. s. n. s. n. s. n. s. n. s. - 3 months wear (8 hours / day) n. s. n. s. n. s. n. s. s. * s. * n. s. s. s. n. s. - 6 months wear (8 hours / day) n. s. n. s. n. s. n. s. s. * s. * s. s. s. s. - 12 months wear (8 hours / day) n. s. n. s. n. s. n. s. s. * s. * s. s. s. s. Thermal aging tests (ISO 188, MSZ 2049; DIN 83 508) Fatigue change at 70 'C after 1 day aging n. s. n. s. n. s. n. s. n. s. n. s. n. s. n. s. n. s. 7 days after aging n. s. n. s. n. s. n. s. s. * s. * n. s. s. s. n. s. 14 days after aging n. s. n. s. n. s. n. s. s. * s. * s. s. s. s.

Note: s = damaged, * = damaged and severe shrinkage

HU 210 201 Β

It can be seen from the summary table that in the case of mixture 3a, in particular, the aging properties and in the case of mixtures 3b-3d some of the highlighted properties (3b: permanent deformation; 3c, 3d: fatigue resistance) are much weaker than those obtained according to the in none of the cases did we experience simultaneous improvement of the properties important for use. It is also apparent from Table 3 that the individual components are available in the form of aqueous dispersions and that the removal of this water from the system can only be accomplished with considerable energy use.

The main advantages of the insole material produced by the process according to the invention are thus:

- elasticity, fatigue resistance and permanent deformation are more favorable than products manufactured according to the state of the art;

- the above-mentioned advantageous properties are not significantly impaired during storage and use, and thus the life of the product is considerably increased;

- the energy requirement of the process is significantly lower, as there is no need to evaporate 40-50% of the water typical of latex technology.

Claims (1)

A process for the production of an insole at 100 ° C from 20 to 100 parts by weight of Defo hardness, from 20 to 100 parts by weight of natural rubber or synthetic polyisoprene, from 0.5 to 350 parts by weight of filler, plasticizer, vulcanizer, dye and other customary additives and additives. or more members thereof, in addition to the weight of the vulcanizing agent, preferably using a blowing agent having a decomposition (evaporation) rate above the vulcanization rate, preferably at a rate of (l. 2-8) times and shearing the mixture at 50-110'C. by vulcanizing at 120-200 ° C, characterized in that 1.2 times N, N-dinitrosopentamethylene tetramine as a vulcanizing agent and 1.3 times azodiisobutyronitrile as a vulcanizing agent and 1.3 times as a vulcanizing agent and as a blowing agent nt dicumyl peroxide and the blowing agent used in an 8-fold amount of p, p'-oxybis (benzenesulfonyl hydrazide) respectively.