Field of technology

The invention relates to a biodegradable walking shoes comprising an upper with a lining and a stitched insole and an outsole attached to the upper with an integrated insole and a thermo-counter, all of the above-mentioned shoe components being made of biodegradable materials.

State of the art

Currently many biodegradable components of footwear are known.

For example, PCT International Application W02006070421 states that the subject matter of the solution is footwear comprising a sole, an insole, an internal coating (lining) and an upper which are made of a biodegradable material. More precisely, however, is specified only the material of the lining and the upper, which are made of fibres based on biopolymers, such as cellulose derivatives, lignin derivatives, soy proteins and their derivatives, polysaccharides, chitin and its derivatives, or hydroxyalkanoates. In further specification, chitin-chitosan is mentioned as the fibre material, in an amount of 5 to 40 wt. % combined with 60 to 95 wt. % of a cellulose material.

PCT International Patent Application WO2012099357 discloses a biodegradable foam composition for insoles using a mixed polylactic acid-copolymer substrate, further comprising 1 to 10 parts by weight of a plasticizer, 1 to 10 parts by weight of a silane coupling agent, 0.1 to 1.5 part by weight of crosslinking agent, 2 to 5 parts by weight of blowing agent, 1 to 10 parts by weight of metal oxide, 0.5 to stearic acid, or 1 to 10 parts by weight of calcium carbonate (all based on 100 parts by weight of the mixed substrate).

Biodegradable foam material for insoles is addressed by Chinese patent application CN111440423. The biodegradable material contains 100 parts by weight of biodegradable resin; 0.5 to 5 wt. parts of colour masterbatch, 0.5 to 10 wt. parts of a nucleating agent; 0.2 to 1 wt. part of antioxidant; 0 to 1.5 wt. part of stearic acid; 0 to 1 part by weight of a cell stabilizer. The biodegradable resin consists of one or more materials selected from the group comprising polybutylene succinate, polybutylene adipate, polybutylene terephthalate, polybutylene succinate terephthalate copolymer, polybutylene succinate-adipate copolymer, poly-3- glycolate, polyhydroxyvalerate, 3-hydroxybutyrate-3-hydroxyvalerate copolymer, polycapro lactone and polylactic acid. Another Chinese patent application CN 110564137 deals with a fully biodegradable sole with abrasion resistance of 70-75 mm3, a hardness of 62 to 78 Shore A and a tensile strength of 160 to 180 Kgf / cm2. It is prepared by extruding or injecting molding from a mixture of biodegradable thermoplastic polyurethane which contains 80 to 100 parts by weight of thermoplastic polyurethane, 1 to 10 parts by weight of biodegradable agent and 2 to 15 parts by weight of phenolic resin. The biodegradable agent comprises a biological expanding agent, a glutamic acid composition and a biological enzyme in a weight ratio (0.01-5) :(0.01-5): 1, wherein the glutamic acid composition comprises glutamic acid, glutaric acid and polylactic acid.

As indicated above, all the published solutions are individual biodegradable components of footwear. So far, however, there is no conceptual solution for biodegradable footwear, where the combination of individual biodegradable footwear components (e.g. in terms of matching the periods required for their degradation) would be sophisticatedly addressed so that it would be possible to talk about biodegradable footwear as a whole.

Background of the invention

The biodegradable walking shoes according to the invention, compostable at the time its functional life has ended, consisting of an upper with lining, stitched insole and an outsole, attached to the upper, with an integrated insole and a thermo-counter, contribute to a large extent to overcoming the above-mentioned drawbacks of the known solutions.

Ground of the invention consists in that in order to control the biodegradability of the shoe as a whole to low molecular weight compounds such as carbon dioxide, water and compost in a maximum time horizon of 20 years, the upper and lining are made of biodegradable vegetable tanned leather with seams made by threads, which are as well as the shoelaces made exclusively of biodegradable fibres, the stitched insole is cotton or linen and the outsole based on reactive biodegradable polyurethane is attached to the upper without adhesives, directly during the synthesis of polyurethane. It is synthesized by the reaction of the polyol component and the isocyanate component in a weight ratio from 1: 0.4 to 1: 4.

The polyol component consists of a mixture of 100 wt. parts of polyester polyol with a molecular weight of 500 to 5000 g/mol and a hydroxyl number of 20 to 100 mg KOH/g, 1 to 30 wt. parts of a diol-based chain extender with a molecular weight of 50 to 400 g/mol and a hydroxyl number of 200 to 2,000 mg KOH/g, 0.1 to 2 wt. parts of water as blowing agent, 0.05 to 2 wt. parts of amine-based catalyst and 1 to 5 wt. dye parts. The isocyanate component consists of a polyisocyanate with an NCO group content of 5 to 30% by weight. To advantageously control the biodegradability of the shoe as a whole into low molecular weight compounds such as carbon dioxide, water and compost over a period of 5, 10 or 15 years, the upper and lining are made of biodegradable vegetable tanned leather with seams made by threads which are as well as the shoelaces made exclusively of biodegradable fibres, the stitched insole is cotton or linen and the outsole based on reactive biodegradable polyurethane is attached to the upper without adhesives, directly during the synthesis of polyurethane. In these preferred embodiments - to control the biodegradability over a period of 5, 10 or 15 years - it is synthesized by the reaction of the polyol component and the isocyanate component in a weight ratio of 1: 0.8 to 1: 1.1, with the polyol component being mixture of 100 wt. parts of polyester polyol with a molecular weight of 1900 to 2300 g/mol and with a hydroxyl number of 50 to 60 mg KOH/g, 5 to 20 wt. parts of a diol-based chain extender with a molecular weight of 50 to 100 g/mol and a hydroxyl number of 1000 to 2,000 mg KOH/g, 0.3 to 0.8 wt. parts of water as blowing agent, 0.05 to 0.4 wt. part of amine-based catalyst and 1 to 3 wt. parts of the dye and the isocyanate component consisting of a polyisocyanate with an NCO group content of 15 to 20% by weight.

An insole with a thickness of 10 to 12 mm made of whipped latex of natural or synthetic rubber and with the attached paper or a cellulose layer 1 to 5 mm thick is preferably integrated into the outsole. Both layers of the integrated insole are glued together with a polyurethane water-soluble adhesive.

A thermo-counter made of natural resin and cellulose fibre is also preferably attached to the outsole.

The biodegradable fibres for the seams of the upper and for shoelaces are preferably natural fibres selected from the group comprising cotton, linen, wool, coconut and bamboo fibres.

The main benefit of the biodegradable walking shoes according to the invention consists in the sophisticated combination of the selected biodegradable footwear materials within a shoe as a whole with a new feature - adjustable and fast biodegradability compared to the footwear produced so far. Regarding the fact that biodegradability can also be formulated as a time limit of utility, biodegradable footwear can also be defined as footwear with expiration date, provided that at the final phase of its life cycle, the footwear is compostable.

In this connection, it can be said that in the time horizon of 5 to 15 years, all parts of the footwear according to the invention will be evenly decomposed into low-molecular compounds such as carbon dioxide, water and compost. With respect to the biodegradability time of the footwear as a whole, the time of the biodegradability of the outsole is limiting, adjustable by the modification of the composition of the reactive biodegradable polyurethane in the above- mentioned range of 5 to 15 years. However, the requirements for mechanical properties of the outsole must also be taken into account - in general, harder outsoles, where the content of butanediol or monoethylene glycol as crosslinkers in the composition of the reactive biodegradable polyurethane is higher, have a longer biodegradability period. This is illustrated in detail by the following practical examples.

Detailed embodiments of the invention E x a mp l e 1

Biodegradable walking shoe with a hard outsole biodegrading in the time horizon of 15 years consists of an upper with a lining and a stitched insole and an outsole with an integrated insole and a thermo-counter attached to the upper. The upper and the lining of the upper are made of biodegradable vegetable tanned leather with seams made of biodegradable cotton or wool threads, the stitched insole is cotton or linen. Shoelaces are also made of cotton or wool fibres.

The sole based on reactive biodegradable polyurethane is attached to the upper without adhesives, directly during the synthesis of polyurethane. It Is synthesized by the reaction of the polyol component and the isocyanate component in a weight ratio of 1: 1.02. The polyol component consists of a mixture of 100 wt. parts of polyester polyol with a molecular weight of 2000 g/mol and a hydroxyl number of 56 mg KOH/g, 18 wt. parts of a chain extender based on 1,4 butanediol with a molecular weight of 90.12 g/mol and a hydroxyl number of 1245 mg KOH/g, 0.5 wt. part of water as blowing agent, 0.25 wt. part of 1,4-diazobicyclo (222) octane catalyst and 2 wt. carbon black dye parts. The isocyanate component then consists of a mixture of 4,4-diphenylmethane diisocyanate and a polyester polyol containing 18.5% by weight of NCO groups.

The insole is integrated into the outsole with a thickness of 11 mm made of whipped natural rubber latex and with an attached paper layer 2 mm thick, while these layers of the integrated insole are glued together with a water-based polyurethane adhesive.

A thermo-counter made of natural resin and cellulose fibre is also preferably attached to the outsole.

Biodegradation of biodegradable walking shoe is fast due to a combination of the selected biodegradable shoe materials. Within 15 years, all parts of the footwear according to the invention will be evenly decomposed into low molecular weight compounds such as carbon dioxide, water and compost. E x a mp l e 2

Biodegradable walking shoe with a medium- hard outsole biodegrading in the time horizon of 10 years are formed by an upper with a lining and a stitched insole and an outsole with an integrated insole and a thermo-counter attached to the upper. The upper and the lining of the upper are made of biodegradable vegetable tanned leather with seams made of biodegradable linen, coconut or bamboo threads. Shoelaces are also made of flax, coconut or bamboo fibres. The stitched insole is made of linen twill fabric and mo lino cotton.

The outsole based on reactive biodegradable polyurethane is attached to the upper without adhesives, directly during the synthesis of polyurethane. It is synthesized by the reaction of the polyol component and the isocyanate component in a weight ratio of 1: 0.99. The polyol component consists of a mixture of 100 wt. parts of polyester polyol (made from adipic acid and monoethylene glycol) with a molecular weight of 1980 g/mol and a hydroxyl number of 58 mg KOH/g, 9 wt. parts of a chain extender based on monoethylene glycol with a molecular weight of 62.07 g/mol and a hydroxyl number of 1801 mg KOH/g, 0.65 wt. part of water as blowing agent, 0.33 wt. part of the catalyst based on 1,4-diazobicyclo (222) octane and 2.5 wt. part of the dye - titanium white. The isocyanate component then consists of a mixture of 4,4-diphenylmethane diisocyanate and a polyester polyol with an NCO group content of 19.4% by weight.

The outsole is integrated with a 10 mm thick insole made of whipped natural rubber latex and with an attached 4 mm thick paper layer, these layers of the integrated insole being glued together with a polyurethane water-soluble adhesive.

A thermo-counter made of natural resin and cellulose fibre is also preferably attached to the outsole.

Biodegradation of biodegradable walking shoe is fast due to a combination of the selected biodegradable shoe materials. Within 10 years, all parts of the footwear according to the invention will be evenly decomposed into low molecular weight compounds such as carbon dioxide, water and compost.

E x a mp l e 3

Biodegradable walking shoe with soft outsoles biodegrading in the time horizon of 5 years consists of an upper with lining and a stitched insole and an outsole with integrated insole and thermo-counter attached to the upper. The upper and the lining of the upper are made of biodegradable vegetable tanned leather with seams made of biodegradable linen, coconut or bamboo threads. Shoelaces are also made of flax, coconut or bamboo fibres. The stitched insole is made of linen twill fabric and mo lino cotton.

The outsole based on reactive biodegradable polyurethane is attached to the upper without adhesives, directly during the synthesis of polyurethane. It is synthesized by the reaction of the polyol component and the isocyanate component in a weight ratio of 1: 0.91. The polyol component consists of a mixture of 100 wt. parts of polyester polyol (made from adipic acid and butanediol) with a molecular weight of 2200 g/mol and a hydroxyl number of 54 mg KOH/g, 8 wt. parts of a chain extender based on 1,4 butanediol with a molecular weight of 90.12 g/mol and a hydroxyl number of 1245 mg KOH/g, 0.35 wt. part of water as blowing agent, 0.05 wt. part of a catalyst based on dibutyltin laurate and 1 wt. part of the dye. The isocyanate component then consists of a mixture of 4,4-diphenylmethane diisocyanate and a polyester polyol with an NCO group content of 16% by weight.

The outsole is integrated with a 10 mm thick insole made of whipped natural rubber latex and with an attached 4 mm thick paper layer, these layers of the integrated insole being glued together with a polyurethane water-soluble adhesive.

A thermo-counter made of natural resin and cellulose fibre is also preferably attached to the outsole.

Biodegradation of biodegradable walking shoe is fast due to a combination of selected biodegradable shoe materials. Within 5 years, all parts of the footwear according to the invention will be evenly decomposed into low molecular weight compounds such as carbon dioxide, water and compost.

Industrial applicability

The biodegradable walking shoes according to the Invention is compostable at the time its functional life has ended (3 to 4 seasons) and is optimized to control the biodegradability of the footwear as a whole to low molecular weight compounds such as carbon dioxide, water and compost within a maximum time horizon of 20 years, preferably within graduated time horizons of 5, 10 and 15 years. Related to this is another significant benefit of the invention from the point of view of waste management - the change of qualification of used shoes from municipal waste to bio-waste.