CS247016B1 - Polyol component for bonding the polyurethane sole to the upper - Google Patents

Abstract

The solution concerns the footwear industry, in particular the production of polyurethane soles. The solution describes the composition of the recipe for the production of a polyurethane midsole by direct injection onto the upper. Its essence is a polyol component for the production of a material ensuring the connection of the polyurethane sole with the upper, containing a foam stabilizer based on a copolymer of ethylene oxide and propylene oxide and an amine crosslinking catalyst. In addition to the footwear industry, the solution can be used in the plastics industry in the production of polyurethane foams.

Description

The invention relates to the manufacture of footwear with a polyurethane sole by means of a direct "foaming" technology. Quite specifically, the polyol component is designed for bonding the sole to the upper.

The technology of direct foaming of polyurethanes to the upper represents one of the latest technologies of shoe production. Technically, this manufacturing process is solved by first producing a tread part of the sole from a polyol and isocyanate component. The mold cover is replaced with a shoe upper and polyurethane is injected into the space between the sole and the upper, which simultaneously forms a boot of the shoe. While the tread portion of the polyurethane sole requires high abrasion resistance, the midsole is to be flexible, of low specific gravity and of good thermal insulation properties. These technical requirements necessitated separate formulation formulations for the sole and midsole.

Two reactions are characteristic of the isocyanate prepolymer and the polyol component. Both have to be coordinated so that they react under the influence of catalysts. swelling reaction and then isocyanate-polyol gelling reaction.

The balance of both of these reactions is of great importance because too rapid a foaming reaction leads to foam collapse, too early a gelation reaction causing pore closure and thus low foaming of the material.

The course of the reaction is controlled, both with the basic raw materials isocyanate, polyol, low molecular weight diol, as well as auxiliaries such as stabilizers and catalysts. Catalytically non-sweetened system does not allow short molding times to be achieved and thus reduces production productivity. The most commonly used catalyst is a tertiary amine. However, it is often combined with organic metal compounds utilizing their synergistic effect. From a technological point of view, it is necessary to achieve not only desirable molding times, but also a linear foam pitch profile. It is difficult to achieve a uniform ascent profile because during the ascent phase the foam temperature increases significantly and the reaction rate increases despite the decreasing concentration of the reactants. The autocatalytic effect of urea and urethane formation also contributes to this.

The high rate of foam rise in the final foaming phase results in high friction forces and cracks on the product surface.

The effect of the catalysts needs to be aligned with the process of foam formation and stabilization. The essential role of the stabilizer applies to the inner boundary of a foaming fluid. As mentioned above, the isocyanate polyol reaction is delayed and, in fact, only takes place at the end of the foam rise phase. The water-isocyanate reaction, which prevails during the foam rise phase, ultimately leads to the polyurea. The resulting urea intermediate stages are insoluble in the resulting liquid polyurethane mass and precipitate relatively spontaneously as a micredisperse solid phase. By precipitating the associated urea, the stability of the rising foam is greatly reduced and generally collapses. Therefore, a foam stabilizer is added to the polyurethane foam formulations. The technical literature recommends the use of silicone-based copolymers for this purpose. They are products of long-term chemical synthesis, which are expensive and adversely affect the resulting economic relations of production processes. MS. No. 198,727 describes a method of stabilizing the microcell structure of polyurethane gigas at the time of their preparation using petroleum jelly oils.

Generally, polyurethane foam stabilizers have wetting and emulsifying properties. Their role is primarily to reduce the surface inapathication of the solution. If they are added in an amount below a certain critical threshold, cells become very unstable, which gradually coalesce, then boiling and foaming fails. When the stabilizer is used in an amount above the upper limit, the foam reaches the desired height and then sits down. This is explained by the formation of very tiny cells whose walls are thin and of low strength. This is not sufficient to maintain the shape when the gas begins to cool.

The polyol component for bonding the polyurethane sole to the upper consists of a linear polyether polyol, a branched polyester, a low molecular diol and a polyol component. of triethylenediamine according to the invention, characterized in that it contains, per 100 parts by weight, an addition of 0.1 to 5 parts by weight of an organic compound with sterile nitrogen and an active hydrogen queue and 0.1 to b parts by weight of a copolymer of ethylene oxide with propylene oxide g. ;. ·

This blend added to the polyol component of the present invention will provide a linear foam rise profile desired by the technology in particular. The foaming reaction is exothermic and despite the decreasing concentration of the reactants, the temperature of the reacting medium increases rapidly. However, the active hydrogen-containing amine catalyst is incorporated into the nascent macromolecule, thereby gradually losing its catalytic effect.

By linearizing the rate of rise of the foam, there is no high friction force at the rising foam-mold interface and cracks on the product surface. _v \. ·

A copolymer of ethylene oxide with propylene oxide has a very good build-up effect on the flammable polyurethane foam. In particular, it counteracts the destabilizing effect of the precipitated urea. The effect of this copolymer is the integration of insoluble urea into the foamed liquid of the resulting polyurethane by physically binding the hydrophilic ethylene oxide segments of the stabilizer to the polar groups of the polymorphs. The synergistic stabilizing effect of the ethylene oxide / propylene oxide copolymer can be observed using triethanolamine.

In the following description, the use of a copolymer of ethylene oxide with propylene oxide as a stabilizer of the microcell structure and ethanol amines as temporary effect catalysts according to the invention will be explained in more detail by some examples. Example 1

a) Prepolymer - isocyanate component is prepared by mixing for 100 h. d. molten 4,4‘-diphenylmethane diisocyanate with · 75 h. d. 80 ° C of warm linear polyester characterized by mol. weight 2,000 and a hydroxyl value of 56 mg KOH / g. After reacting for two hours, a prepolymer containing 17% of free NCO groups is obtained.

(b) The polyol component shall be prepared by homogenising:

76.50 h. d. linear polyester with mol. weight 2 000

13.50 h. d. of a partially branched polyester having a hydroxyl value of 50 mg KOH / g

7,00 h. d. monoethylene glycol

0.50 h. d. triethylenediamine

0.35 h. d. triethanolamine

0.55 h. d. of a copolymer of ethylene oxide and propylene oxide with a hydroxyl number of 47 mg

KOH / g

0.40 h. d. distilled water 0.50 h. d. UV stabilizer of the indole type

0.70 h. d. antioxidant 2,6 target butyl p. cresol.

The polyol component is characterized by a hydroxyl value of 205 mg KOH / g and a water content of 0.47%.

c) After homogenization of the two components in a ratio of 90: 100 in favor of the polyol component, a flexible polyurethane foam is obtained with a very short demoulding time of up to 3 ml with the following physics. mechanical properties.

hardness [ShAj 48—55 tensile strength [MPa] min. 5 elongation [%] min. 400 structural strength [kNm ¹ ] min. 8 density of loose foamed foam [kg. nr ³ j 230

Example 2

a) The isocyanate component is prepared by mixing for 100 h. d. of molten 4,4‘-diphenylmethane diisocyanate with 60 h. d. a linear polyester characterized by a molecular weight of 2,000 and a hydroxyl value of 56 mg KOH / g.

The reacted prepolymer has 19% free isocyanate groups.

b) The polyol component is prepared by homogenization;

100 h. d. Linear polyester with a molecular weight of 2 000

6.3 h. d. monoethylene glycol 1.2 h. d. triethanolamine 0.7 h. d. triethylenediamine 0.8 h. d. foam stabilizer based on a mixed copolymer of ethylene oxide and pnopylene oxide with a hydroxyl number of 35 mg KOH per gram

0.6 h. d. distilled water 3.0 h. d. white stabilized paste prepared from linear polyester UV stabilizer, antioxidant and titanium dioxide.

The polyol component is characterized by a hydroxyl value of 195 mg KOH / g and a water content of 0.43%.

cj After mixing the two components according to the stoechometry, the test piquette has the following physico-mechanical properties:

specific weight [kg. m ” ³ ] 450 hardness [ShA] 45—55 tensile strength [MPa] min. 5.5 elongation [%] min. 375 structural strength [kNnr ' ¹ ] min. Specific gravity of loose foamed foam [kg. ni ³ ] 250

As organic compounds with tertiary nitrogen and tertiary active hydrogen, triethanolamine or diethanolamine may be used. The nonionic surfactant produced on the basis of propylene oxide and ethylene oxide, used as a stabilizer, has the general formula:

HO- (C2H4O) _x - (CsHeO) _y - (C2H4O j _x —H density [kg. M ^-3 ]

Claims (1)

A polyol component for joining a polyurethane sole to an upper consisting of a linear polyether polyol, a branched polyesteirpolyol, a low molecular weight diol and a triethylenediamine, characterized in that the addition of 0.1 to 5 parts by weight of the organic compound is present per 100 parts by weight of the compound. active hydrogen and 0.1 to 5 parts by weight of a copolymer of ethylene laoride with pro-ethylene oxide having a hydroxyl number of 30 to 60 mg KOH / g.