CN112638192A

CN112638192A - Shoe comprising a sole of thermoplastic material and method for manufacturing such a shoe

Info

Publication number: CN112638192A
Application number: CN201980056181.0A
Authority: CN
Inventors: 埃尔文·帕普盖吉; 罗曼·斯特潘扬; 贾恩·亨德瑞库斯·乌丁
Original assignee: DSM IP Assets BV
Current assignee: Covestro Netherlands BV
Priority date: 2018-09-03
Filing date: 2019-09-03
Publication date: 2021-04-09
Also published as: EP3846655B1; ES2968803T3; EP3846655A1; JP2021535774A; US20210330025A1; KR102660597B1; KR20210047305A; EP3846655C0; WO2020048989A1

Abstract

The present invention relates to a new shoe comprising a sole of thermoplastic material adhered to an upper with a hot melt adhesive applied between the sole and the upper, wherein the hot melt adhesive is fused with the thermoplastic material. Advantageously, by heating the hot-melt adhesive to a temperature T_HMTo soften it, heating the second body to have a melting temperature T_MTo a temperature of less than T_MTemperature T of_SUBWhile ensuring (T)_HM+T_SUB) (T2 is equal to or higher than_M‑10℃) To produce fusion.

Description

Shoe comprising a sole of thermoplastic material and method for manufacturing such a shoe

Technical Field

The present invention relates to footwear and its manufacture. More particularly, the invention relates to a shoe having a sole of thermoplastic material and a method for preparing a workpiece that can be used for manufacturing such a shoe.

Background

Contemporary shoes contain the same basic parts. All shoes have a sole, i.e. a sole of the shoe, which is in contact with the ground. The sole can be made of a variety of materials, although the soles of most modern shoes are made of natural rubber, polyurethane, polyvinyl chloride (PVC) or Ethylene Vinyl Acetate (EVA). The sole may be a simple, single layer of a single material, but most commonly, the sole is more complex, having multiple structures or layers and materials. When various layers are used, the sole may be comprised of an insole (also referred to as sock liner), a midsole, and an outsole (i.e., the layer that is in direct contact with the ground). The midsole is the layer between the outsole and the insole where it is typically used for cushioning.

Another common part of all shoes is the upper (upper shoe). The upper helps to hold the shoe on the foot. In the simplest case, such as sandals or chevrons, this may be just a few straps for securing the sole in place. The upper of closed shoes (e.g., boots, athletic shoes, and most men's shoes) can be more complex. This part is often decorated or made in a certain pattern to make it look attractive. The upper may be attached to the sole by plastic, leather, or rubber sewn between it and the sole, or may be glued to the sole using an adhesive. In the manufacture of sports shoes, in most cases, the upper is glued to the mid-sole (the latter being an important item for such shoes), using solvent-based adhesives, either using aqueous solvents (e.g. water-based PUDs, polyurethane adhesives) or using non-aqueous solvents (e.g. polychloroprene or styrene-isoprene-styrene adhesives). While solvent-based adhesives are relatively expensive, inherently require long processing times, and while in practice special care is required to prevent environmental damage and deleterious health effects (caused by many non-aqueous solvents), such adhesives are superior to hot melt adhesives. The advantage of hot melt adhesives is that they are (almost) solvent-free and allow very short processing times without any tendency to foam during processing, but the adhesion properties on relatively smooth shoe soles are relatively poor. This is particularly true when adhering the upper to a thermoplastic sole. In principle, the latter type of material would be more preferred than the commonly used EVA (commonly used in midsoles) because it has the property of being easily recycled compared to EVA, whereas the final foam of EVA has a thermoset, which prevents recycling by simply melting the material and reprocessing it. Nonetheless, because of the difficulty in gluing the upper to the thermoplastic sole, EVA remains the polymer of choice for bonding the upper using solvent-based adhesives.

For decades, the problem of low-quality adhesion of the upper to the thermoplastic sole has been known, especially when hot-melt adhesives are used.

GB 1247855 (filed in 1967, published in 1971) describes the problem of using hot melt adhesives to bond uppers to plasticized polyvinyl chloride shoe soles. The solution proposed in this patent is to use a polyester hot melt adhesive containing a certain amount of nitrogen-containing organic compounds having polar groups, such as N-butyl-benzenesulfonamide or N-ethyl-p-toluenesulfonamide. However, such compounds are associated with health hazards. N-butylbenzenesulfonamide is neurotoxic and has been found to induce spastic myelopathy in rabbits. N-ethyl-p-toluenesulfonamide is toxic and extremely irritating.

US 3,168,754 (filed 1961, published 1965) also mentions the problem of using hot melt adhesives to adhere the upper to the sole, despite the fact that hot melt adhesives have found great utility in areas other than sole attachment, at the end of the 1950 s. The' 754 patent states (col. 1, lines 28-30) "that attempts to bond an outsole to an upper using known hot melt adhesive processes have insufficient bonding force, apparently due to unsatisfactory penetration and/or wetting of the surfaces to be bonded. The proposed solution aims to improve the permeability and wettability of hot melt adhesives by using a process of repeated heating and cooling. This increases the process time and may still not provide sufficient bonding, particularly when adhered to a thermoplastic sole.

US 3,212,115 (filed 1959, published 1965) demonstrates that the use of hot melt adhesives in the manufacture of shoes leads to several disadvantages, the most important of which is bond failure at the temperatures involved in the actual handling or use of such bonded structures. The proposed solution is a complex process involving depositing a relatively thick body of molten, crystallizable hot melt adhesive on a surface, supercooling the adhesive to a temperature below its crystallization temperature but above its second order transition temperature, pressing said body of supercooled adhesive between said surface and a second surface deforming the body of adhesive, wherein the deformation should induce crystallization and affect the orientation of the deposited adhesive molecules to increase the tensile strength and toughness of the adhesive.

GB 2048897 (filed in 1979, published 1980) states that (page 1, lines 14-16), the acceptance of known elastomeric base materials for adhesives and thermoplastics is generally unsatisfactory. The proposed solution is to use an aggressive primer comprising an organic halogen donor, such as a mixture of isocyanuric chloride and a sulfonamide (e.g., p-toluenesulfonamide), to promote adhesion. These primers are toxic, irritating and environmentally unfriendly.

US 6,497,786 (published 2002, 1997) describes the potential advantage of using a less solvent adhesive, but indicates that the need to heat the adhesive to enable it to be used and applying the adhesive is disadvantageous, particularly because today's sole materials may deform at high temperatures. The' 786 patent suggests the use of microwaves to locally heat the adhesive while maintaining the sole at a low temperature. However, this solution requires very complex equipment to heat the adhesive exclusively. In addition, the problem of insufficient adhesion when using hot melt adhesives has neither been addressed nor truly solved.

Object of the Invention

It is an object of the present invention to provide a new shoe and a method of assembling a workpiece that can be used to manufacture such a shoe that alleviates the disadvantages of the prior art.

Disclosure of Invention

In order to meet the object of the invention, a new shoe has been devised, which comprises a sole of thermoplastic material, said sole being adhered to an upper with a hot melt adhesive applied between the sole and the upper, wherein the hot melt adhesive is fused with the thermoplastic material.

The inventors have surprisingly found that when the method provides a thermoplastic material for the fusion of hot melt adhesives, good adhesion using standard hot melt adhesives can be obtained, even when adhered to a body of thermoplastic material having a very smooth surface. This finding is based on the following recognition: although the thermoplastic material itself does not readily adhere to another material, in particular a hot melt adhesive, it provides the option of melting the upper region of the body (i.e. the region having a thickness exceeding the molecular dimension, at least in the order of microns or more, i.e. a number of μm or more, e.g. 2,3, 4, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100 or more), which in turn may provide the option of fusing molecules in the melted hot melt adhesive and the melted upper region of the thermoplastic body, i.e. mixing and forming a new material which acts as a bridge between the hot melt adhesive on the one hand and the thermoplastic body on the other hand.

The invention also relates to a method for assembling a piece for manufacturing shoes, comprising heating a hot-melt adhesive to a temperature T_HMSo as to soften it and enable application, heating the thermoplastic body so as to obtain a temperature T of the thermoplastic material lower than its melting temperature_SUBSo that (T)_HM+T_SUB) A melting temperature greater than or equal to 10 ℃ (T) of the thermoplastic material_M-10 ℃ C. When these specific temperatures are used, the total heat available is sufficient to melt the upper region of the thermoplastic body on contact with the hot melt adhesive and to allow the two molten substances to fuse, in particular when pressure is applied, for example in the application of the upper (where it is applied)The molten hot melt adhesive may have been applied to the sole prior to application of the upper, or may have been previously applied to the upper and maintained at a sufficient temperature when in separate contact with the upper). Although the melting of the thin upper region of the thermoplastic body may be accomplished in various ways (e.g. convection using hot air or liquid, radiation, etc.), it has been found that a very simple way is to utilize the thermal capacity of the hot melt adhesive and the body itself to provide the heat for melting the upper region of the thermoplastic body.

In any case, by providing fusion between the hot melt adhesive and the thermoplastic body, a very strong mechanical connection can be obtained without the need to apply special organic molecules, primers or to use complicated heating procedures and equipment.

Definition of

"shoe" is an external covering for a human foot, usually with a thick or stiff sole with an attached heel and an upper (also called upper) of lighter material (e.g. textile or leather sheet).

A "hot melt adhesive" is a thermoplastic adhesive that is free (less than 1 or 2 weight percent) of solvent. Upon heating, the adhesive softens for application to a substrate. Preferably, the first order phase change is experienced when the hot melt adhesive is heated and will change from a solid to a liquid.

A "thermoplastic" material is a material (typically a synthetic polymeric material) that becomes plastic (e.g. deformable) when heated and hardens to retain a desired shape when cooled and is able to reversibly repeat this process. Melting temperature (T) of thermoplastic material_M) Is the peak melting temperature as defined in ASTM D3418, measured in the second heating step of a Differential Scanning Calorimetry (DSC) experiment at a temperature ramp rate of 10 ℃/min. If multiple peaks are present, the first peak (e.g., lowest temperature) corresponding to melting of the hard block of the thermoplastic elastomer should be used.

The "first order phase transition temperature" of a material is the temperature at which the material undergoes a discontinuous change in density. Examples of first order transitions are melting (solid-liquid conversion) and evaporation (liquid-gas conversion). The glass transition is a second order transition because there is no discrete change in density.

The "body" is a solid 3-dimensional object having a predetermined size.

"fusion" refers to the joining by melting or as if by melting to form a single entity, particularly resulting in no boundary lines and/or distinct boundaries between materials in a Scanning Electron Microscope (SEM) picture magnified 500 to 1000 times.

"textile material" means a material (greater than 50%, e.g., greater than 55%, 60%, 65%, 70%, 75%, 80%, 85%, or even greater than 90%) that is essentially composed of fibrous material (e.g., polymeric yarns).

By a body "consisting of a thermoplastic material" is meant that the basic structure of the body consists of a thermoplastic material, which material typically comprises more than 50% (by weight) of a thermoplastic polymer, preferably more than 60%, 70%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or even up to 100% of a thermoplastic polymer.

A "workpiece" is a component of a material used to make a final product.

A "smooth" surface is a surface without a regular or irregular pattern of protrusions or without a regular or irregular pattern of indentations or cavities, which protrusions are perceived as "rough" by human touch, i.e. a surface without a pattern of protrusions having an average height above 100 μm, preferably not above 90 μm, 80 μm, 70 μm, 60 μm, 50 μm, 40 μm, 30 μm, 20 μm, 10 μm, 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2 μm or even 1 μm, which indentations or cavities are visually perceived as the opposite of such protrusions, i.e. a surface without a pattern of indentations having an average depth above 100 μm, preferably not above 90 μm, 80 μm, 70 μm, 60 μm, 50 μm, 40 μm, 30 μm, 20 μm, 10 μm, 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2 μm or even 1 μm.

Modes for carrying out the invention

Thermoplastic materials particularly suitable for the sole of the shoe according to the invention are thermoplastic elastomers. Thermoplastic elastomers (TPEs), sometimes also referred to as thermoplastic rubbers, are a class of physical blends or copolymers of polymers composed of materials having both thermoplastic and elastomeric properties. Commercial TPEs can be divided into six general categories: styrene block copolymers, thermoplastic olefins, elastomeric alloys, thermoplastic polyurethanes, thermoplastic copolyesters and thermoplastic polyamides.

In one embodiment, the footwear according to the present invention has a sole comprising a foamed composition comprising 70 to 99 wt% of a thermoplastic copolyester elastomer, based on the total amount of the foamed composition. In another embodiment, the foamed composition comprises 70 to 99 weight percent of the thermoplastic copolyester elastomer and 1 to 30 weight percent of the plasticizer, based on the total amount of the foamed composition. Such compositions are disclosed in WO 2018134166. Surprisingly, the inventors have found that the presence of a combination of a plasticizer and a thermoplastic copolyester elastomer leads to the possibility of obtaining a low density foam exhibiting less cracks, which is ideally suitable as sole material for shoes. Lower density, crack-free foams are very attractive because they are an important feature in light weight advantageous applications, particularly in athletic shoes. In this context, foaming compositions are understood to be known to the person skilled in the art. Preferably, the foamed composition has a density of 0.1 to 0.7g/cm³Typically 0.2 to 0.3g/cm³In particular for sports shoes. A thermoplastic copolyester elastomer is herein understood to be a copolymer comprising hard segments built up from polyester repeating units and soft segments selected from another type of polymer.

In another embodiment, the thermoplastic copolyester elastomer comprises a hard segment constructed from polyester repeating units derived from at least one aliphatic diol and at least one aromatic dicarboxylic acid or ester thereof, and a soft segment selected from the group consisting of aliphatic polyethers, aliphatic polyesters, aliphatic polycarbonates, dimerized fatty acids, and dimerized fatty diols, and combinations thereof.

The aliphatic diols generally contain 2 to 10C atoms, preferably 2 to 6C atoms. Examples thereof include ethylene glycol, 1, 2-propanediol, 1, 3-propanediol, butanediol, 1, 2-hexanediol, 1, 6-hexanediol, 1, 4-butanediol, 1, 4-cyclohexanediol, 1, 4-cyclohexanedimethanol, and mixtures thereof. Preferably, 1, 4-butanediol is used. Suitable aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, 2, 6-naphthalenedicarboxylic acid, and 4,4' -diphenyldicarboxylic acid, and mixtures thereof. Also very suitable are mixtures of 4,4 '-diphenyldicarboxylic acid and 2, 6-naphthalenedicarboxylic acid or mixtures of 4,4' -diphenyldicarboxylic acid and terephthalic acid. The mixing ratio of 4,4 '-diphenyldicarboxylic acid to 2, 6-naphthalenedicarboxylic acid or the mixing ratio of 4,4' -diphenyldicarboxylic acid to terephthalic acid is preferably selected from between 40:60 and 60:40 on a weight basis to optimize the melting temperature of the thermoplastic copolyester.

The hard segment preferably has as repeating unit a repeating unit selected from the group consisting of: selected from the group consisting of ethylene terephthalate (PET), trimethylene terephthalate (PPT), tetramethylene terephthalate (PBT), polyethylene dibenzoate, polyethylene naphthalate, polybutylene dibenzoate, polybutylene naphthalate, polypropylene dibenzoate and polypropylene naphthalate, and combinations thereof. Preferably, the hard segment is butylene terephthalate (PBT) because the thermoplastic copolyester elastomer comprising a hard segment of PBT exhibits favorable crystallization behavior and high melting point, which results in a thermoplastic copolyester elastomer with good processability and excellent heat and chemical resistance.

The soft segment selected from the group consisting of aliphatic polyesters has repeating units derived from aliphatic diols and aliphatic dicarboxylic acids or repeating units derived from lactones. Suitable aliphatic diols generally contain 2 to 20C atoms, preferably 3 to 15C atoms, in the chain and aliphatic dicarboxylic acids contain 2 to 20C atoms, preferably 4 to 15C atoms. Examples thereof include ethylene glycol, propylene glycol, butylene glycol, 1, 2-hexanediol, 1, 6-hexanediol, 1, 4-butanediol, cyclohexanediol, cyclohexanedimethanol and mixtures thereof. Preferably, 1, 4-butanediol is used. Suitable aliphatic dicarboxylic acids include sebacic acid, 1, 3-cyclohexanedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, adipic acid, glutaric acid, 2-ethylsuberic acid, cyclopentanedicarboxylic acid, decahydro-1, 5-naphthalenedicarboxylic acid, 4 '-dicyclohexyldicarboxylic acid, decahydro-2, 6-naphthalenedicarboxylic acid, 4' -methylenebis (cyclohexyl) carboxylic acid and 2, 5-furandicarboxylic acid. Preferred acids are sebacic acid, adipic acid, 1, 3-cyclohexanedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid. Most preferred is adipic acid. Preferably, the soft segments are polybutylene adipate (PBA) which can be obtained from 1, 4-butanediol and adipic acid.

The soft segments may be aliphatic polyethers which may comprise units of polyalkylene oxides such as polyethylene oxide and polypropylene oxide and polytetrahydrofuran and combinations thereof, either as separate segments or in combination in one segment. The combination is, for example, an ethylene oxide-capped polypropylene oxide.

The preferred soft segment is Polytetrahydrofuran (PTMO). It is also possible to use soft segments comprising block copolymers in which two types of diols react to form soft segments, for example based on polyethylene oxide (PEO) and polypropylene oxide (PPO). The latter is also called PEO-PPO-PEO because the PEO blocks are located at the ends of the soft segments because the PEO reacts best with the hard segments. PTMO, PPO and PEO based soft segments allow for foams with lower densities.

The soft segment can be an aliphatic polycarbonate and is comprised of repeating units derived from at least one alkylene carbonate. Preferably, the repeating unit as an alkylene carbonate is represented by the formula:

wherein R is₁Alkyl, and X is 2-20.

Preferably, R₁CH2 and x 6, the alkylene carbonate is hexamethylene carbonate, since this provides the product with high heat resistance and is readily available.

The soft segment can be a dimerized fatty acid or dimerized fatty diol, and combinations thereof. The dimerized fatty acid may contain 32 to 44 carbon atoms. Preferably, the dimerized fatty acid contains 36 carbon atoms. Dimer fatty diols which may be derived from dimer fatty acids as disclosed above are also suitable. For example, dimer fatty diol may be obtained as a derivative of a dimer fatty acid by hydrogenation of the carboxylic acid groups of the dimer fatty acid or ester groups prepared therefrom. Other derivatives are obtainable by converting carboxylic acid groups or ester groups made therefrom into amide, nitrile, amine or isocyanate groups.

In a preferred embodiment, the foaming composition comprises a thermoplastic copolyester elastomer with hard segments selected from PBT or PET, preferably PBT, and soft segments selected from the group consisting of polybutylene adipate (PBA), polyethylene oxide (PEO), polypropylene oxide (PPO), Polytetrahydrofuran (PTMO), PEO-PPO-PEO and combinations thereof, preferably PTMO, as this provides an article exhibiting a low density. In a further preferred embodiment, the foamed composition comprises a thermoplastic copolyether-ester elastomer consisting of PBT and PTMO.

Plasticizers are substances known per se to the person skilled in the art and reduce the hardness of the composition and/or increase the strain at break of the composition, for example compared to the elastomer itself. The plasticizer is present in an amount of from 1 to 30 wt.%, preferably from 5 to 25 wt.%, even more preferably from 8 to 20 wt.%, based on the total amount of the foaming composition. Plasticizers include, for example, phthalic acid esters, dibasic acid esters, mellitic acid salts and esters thereof, cyclohexanoic acid esters, citric acid esters, phosphoric acid esters, modified vegetable oil esters, benzoic acid esters, and petroleum oils, and combinations thereof. Preferably, the plasticizer is selected from the group consisting of triphenyl phosphate (TPP), t-butylphenyl diphenyl phosphate (Mono-t-but-TPP), phenyl bis (t-butylphenyl) phosphate (bis-t-but-TPP), tris (p-t-butylphenyl) phosphate (tri-t-but-TPP), resorcinol bis (diphenyl phosphate) (RDP), dichloropropyl phosphate, bisphenol a bis (diphenyl phosphate) (BDP), tricresyl phosphate (TCP), triethyl phosphate, tributyl phosphate (TBP), tris (2-ethylhexyl) phosphate, trimethyl phosphate, Epoxidized Soybean Oil (ESO), Epoxidized Palm Oil (EPO), Epoxidized Linseed Oil (ELO), and argan oil, and combinations thereof.

Alternatively, the shoe according to the invention comprises a sole of thermoplastic material, said sole being adhered to an upper with a hot melt adhesive, the hot melt adhesive being applied between the sole and the upper, wherein the hot melt adhesive is fused with the thermoplastic material, and wherein the sole comprises Thermoplastic Polyurethane (TPU). Advantageously, the sole comprises the TPU in an amount of 70 to 100 wt. -%, based on the total amount of the sole composition. The sole may advantageously comprise expanded (i.e. foamed) TPU, for example as disclosed in WO94/20568 or US 2010/0222442. Thermoplastic polyurethanes and processes for their production are well known. TPUs are block copolymers consisting of alternating sequences of domains or hard and soft segments formed by (1) reaction of diisocyanates with short-chain diols (so-called chain extenders) and (2) reaction of diisocyanates with long-chain diols. By varying the proportions, structures and/or molecular weights of the reaction compounds, various TPUs can be produced. Preferably, polyester-based TPUs are used for shoe soles, such as those derived from adipates.

In another embodiment, the upper includes a layer of textile material adjacent to the sole. The textile material appears to be ideally suited to be joined to the sole via a hot-melt adhesive without any special measures being taken, which may be due to the irregular surface provided by the constituent yarns. The textile material may comprise polymer yarns, for example yarns made of polyester polymers. This is particularly advantageous when the sole is also made of a polyester material, allowing easy recycling of the assembly of upper and sole. In the context of the present invention, an insole, a midsole and an outsole are all considered to be soles of footwear.

In one embodiment, the hot melt adhesive comprises as a major constituent (i.e., at least 50% by weight of the adhesive composition) a polymer selected from the group consisting of (co) polyurethanes, (co) polycarbonates, (co) polyesters, (co) polyamides, (co) poly (ester-amides), mixtures thereof, and/or copolymers thereof. Preferably, the hot melt adhesive comprises (co) polyester as a main constituent. The (co) polyester may be prepared from an acid selected from the group consisting of terephthalic acid, isophthalic acid, succinic acid, suberic acid, pimelic acid, adipic acid, fumaric acid, maleic acid, itaconic acid, dimer fatty acids, sebacic acid, azelaic acid, sulfoisophthalic acid or metal salts thereof, 1, 3-cyclohexanedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, furandicarboxylic acid, trimellitic anhydride and/or dialkyl esters thereof, mixtures thereof, with an acid selected from the group consisting of ethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 5-pentanediol, neopentyl glycol, diethanol, triethylene glycol, 1, 8-octanediol, 2, 4-trimethyl-1, 3-pentanediol, polyethylene glycol, polypropylene glycol, 2,4, 4-tetramethyl-1, 3-cyclobutanediol, 2, 4-dimethyl-2-ethylhexane-1, 3-diol, 2-dimethyl-1, 3-propanediol, 2-ethyl-2-butyl-1, 3-propanediol, 2-ethyl-2-isobutyl-1, 3-propanediol, 1, 3-butanediol, 2, 3-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 4-butanediol, dimer fatty acid diol, glycerol, pentaerythritol, dipentaerythritol and/or mixtures thereof. Dimerized fatty acids, dimerized fatty diols, and/or dimerized fatty diamines (e.g., available from Croda) may also be used as potential building blocks for obtaining polymers.

Preferably, the (co) polyester is obtained and/or obtainable by reacting at least one acid selected from the group consisting of terephthalic acid, 2, 5-furandicarboxylic acid, adipic acid, fumaric acid, dimerized fatty acid, sebacic acid, azelaic acid, succinic acid and/or combinations thereof with at least one alcohol selected from the group consisting of ethylene glycol, 1, 6-hexanediol, 1, 4-butanediol, dimerized fatty acid diol and/or combinations thereof.

Esterification polymerization processes for preparing the polyesters used in the compositions of the present invention are well known in the art and need not be described in detail herein. On the other hand, they are generally carried out in the melt optionally using catalysts such as titanium or tin-based catalysts, with the proviso that any water (or alcohol) formed by the condensation reaction is removed. Preferably, if the polyester resins contain carboxylic acid functional groups, they are derived from polyacids and/or anhydrides.

In yet another embodiment, the upper, the hot melt adhesive and the sole are made of a polyester material.

In another embodiment of the shoe according to the invention, the hot-melt adhesive is semi-crystalline (i.e. it at least partially transforms into crystalline when cured under equilibrium conditions), preferably having a melting enthalpy of from 1 to 80J/g, more preferably from 5 to 60J/g, even more preferably from 10 to 40J/g. The enthalpy of Fusion is determined on the basis of ASTM Standard D3418 ("Standard Test Method for measuring the Transition Temperatures and Enthalpies of melting and Crystallization of Polymers by Differential Scanning Calorimetry"), which uses a Meter STARe Differential Scanning calorimeter. For the actual measurement, approximately 10mg of the adhesive sample was placed in a sample cup. The sample was held in an oven at 150 ℃ for 15 minutes. Thereafter, the sample was cooled to 50 ℃ and then heated to 250 ℃ at a rate of 5 ℃/min. The sample was held at 250 ℃ for 1 minute and then cooled directly to 25 ℃ at a rate of 5 ℃/min. The enthalpy of fusion of the sample polymer is obtained from the DSC data obtained.

As mentioned above, the invention is also embodied in a method of assembling a workpiece that can be used for manufacturing a shoe according to the invention, said workpiece comprising a first body mechanically connected to a second body (i.e. a sole) by adhering the first body (i.e. an upper) to a surface of the second body, said second body having a melting temperature T_MThe method comprising:

heating the hot melt adhesive to a temperature T_HMSo as to soften it;

-heating the second body to bring the thermoplastic material below T_MTemperature T of_SUB；

-applying a heated hot melt adhesive to a surface of the heated second body;

-applying the first body to the second body to form a workpiece;

-cooling the workpiece to harden the hot melt adhesive;

-wherein the temperature is selected such that (T)_HM+T_SUB) (T2 is greater than or equal to_M-10℃)。

The technical features of any of the above-described embodiments of the shoe according to the invention may also be combined with the method.

In another embodiment of the method of assembling a workpiece, the second body is heated in its entirety. Such heating may be established, for example, by warming the entire second body in an oven or microwave oven or in a heated mold. This heating is thus different from the local heating of the upper region, which may be achieved by external radiation or convection, i.e. heating only the outside of the second body.

In particular, in this process, the temperature is chosen such that (T)_HM+T_SUB) [ 2 ] and T_MThe degree of phase difference is selected from the group consisting of-10, -9, -8, -7, -6, -5, -4, -3, -2, -1, 0, +1, +2, +3, +4, +5, +6, +7, +8, +9, +10, +11, +12, +13, +14, +15, +16, +17, +18, +19, and +20 ℃. Higher values result in a greater portion of the upper region of the thermoplastic body melting. However, it is advantageous that this portion should not be too thick, since it does not increase the adhesive strength, but may negatively affect the shape and mechanical properties of the thermoplastic body. Therefore, a preferred upper limit is 20 ℃.

In yet another embodiment, the second body is heated such that the thermoplastic material attains a temperature T_SUBRatio T_MUp to X deg.C, X is selected from the group consisting of 100, 90, 80, 70, 60, 55, 50, 45, 40, 35, and 30. It has been found that it is preferred not to heat the thermoplastic body to a temperature too close to its melting temperature.

The invention will now be further explained using the following non-limiting examples.

Examples

FIG. 1 schematically illustrates the interaction between a hot melt adhesive and various substrates.

Figure 2 schematically shows the components of a workpiece for use in the manufacture of shoes.

Fig. 3 schematically shows a cross-section of material for an upper of an athletic shoe.

Fig. 4 schematically shows a test device for measuring the strength of a mechanical connection caused by a hot melt adhesive.

Figure 5 is an SEM photograph of the joined thermoplastic bodies from example 1.

Example 1 describes the joining of two thermoplastic bodies using a hot melt adhesive.

FIG. 1 shows a schematic view of a

Fig. 1 schematically illustrates the interaction between a hot melt adhesive 4 and various substrates (200, 200', and 200 "). In fig. 1A, the interaction between the layer 4 of hot melt adhesive in hardened form (thus after application in liquid form and subsequent cooling below its curing temperature) and the non-smooth surface of the body 200 is depicted. The surface of the body has various protrusions (201) and indentations (202) that serve as fixation points for the hardened hot melt adhesive. This results in a good mechanical connection between the hot melt adhesive 4 and the main body 200.

In fig. 1B, a case is depicted in which the body 200' has a smooth surface, resulting in no fixing point for the hot melt adhesive 4. This means that if there is a mechanical connection between the layer of hot melt adhesive 4 and the body 200', the mechanical connection is very weak. The layers can be easily separated by applying a slight pulling force to either layer.

In fig. 1C, a situation is depicted in which the main body 200 "is made of a thermoplastic material and the hot melt adhesive is heated sufficiently prior to application to ensure that the upper region of the main body 200" is heated above its melting temperature. In this way, the molecules of the molten body 200 "and the molten hot melt adhesive may be able to mix and bond (fuse) to form a new intermediate material 204 that may ultimately (after all of the molten material has solidified) serve to form a mechanical bridge between the layer of hot melt adhesive 4 and the body 200". Although shown as separately identifiable layers in the schematic of fig. 1C, in practice, layers 4 and 200 "gradually change from one pure material to another, with a gradually changing composition of the mixed material therebetween.

FIG. 2

Fig. 2 shows schematically in cross section the components of a workpiece 1 for the manufacture of shoes (which need not be more than the workpiece itself). In the figures, the part numbered 2 is the (mid) sole of a shoe, in this case consisting of a foaming composition comprising copolyetherester elastomer in an amount of 85% by weight (55% by weight PTMO and 45% by weight PBT relative to the amount of copolyetherester elastomer) and epoxidized soybean oil in an amount of 15% by weight as plasticizers, relative to the total amount of foaming composition, resulting in a density of 0.24g/cm³And T_M160 ℃ CThe foam of (1). The upper 3 consists of a textile base and an outer coating of polyurethane (see figure 3). The part 30 is a section of the upper 3 for adhering the upper 3 to the sole 2 using a hot melt adhesive (see example 1). The outsole 20 is shown in phantom.

FIG. 3

Fig. 3 schematically shows a cross section of the material of the upper 3 for a sports shoe. The upper 3 consists of a textile base layer 31 and an outer coating (32) of polyurethane. Textile layer 31 is the layer that will be used in connection with the sole shown in figure 2.

FIG. 4

Fig. 4 schematically shows a test setup (according to the standardized method ASTM D3936) for measuring the strength of a mechanical connection caused by a hot melt adhesive. In this device, two

bodies

2 and 3 of width L are mechanically connected to a layer 4 of hot melt adhesive. One end of the layers is separated and a separation force F is applied. To make a suitable shoe, the F/L should be greater than 30 newtons per inch (greater than 11.8 newtons per centimeter).

Example 1

Example 1 describes the joining of thermoplastic bodies using hot melt adhesives. In order to evaluate whether it is possible to adhere the first body to the thermoplastic body using a hot melt adhesive, two thermoplastic bodies were selected, in this case foamed thermoplastic bodies, as described in connection with fig. 2. Melting temperature T of these bodies_MIs 160 ℃ (as described in this patent application, determined by ASTM D3418-03). In the first attempt, polyester hot melt adhesives with a melting enthalpy of 27 ± 3J/g (the melting enthalpy was determined using a Mettler star differential scanning calorimeter based on ASTM standard D3418) were used, exhibiting a first order transition temperature (solid to liquid) of about 110 ℃. The hot melt is heated to a temperature of 180 c, so as to be well above its melting temperature, and to the level commonly used to obtain a strong connection using the hot melt. The thermoplastic body is preheated to various temperatures ranging from 80 ℃ to 100 ℃ before the hot melt adhesive is applied, which means (T ℃)_HM+T_SUB) A/2 variation from 130 ℃ to 140 ℃ i.e. the ratio T _M30 to 20 lower. Immediately after the adhesive is applied, the two bodies are pressed together. In any case, a good mechanical connection cannot be obtained. The F/L of each workpiece is less than 5N/inch. This confirms the general knowledge in the art that thermoplastic materials cannot be adequately joined using hot melt adhesives.

In a second attempt, the hot melt adhesive was heated to 210 ℃ (i.e. still well below the temperature at which the polyester hot melt adhesive would (start) degrade (i.e. about 250 ℃)), and the thermoplastic body was heated to a temperature ranging from 120 to 130 ℃, which means (T ℃) (T ℃.))_HM+T_SUB) A 2 varying between 165 ℃ and 170 ℃, i.e. at T_M5 deg. to 10 deg. above. The molten adhesive is provided on one or both sides of the body. In addition to the type of polyester binder used in the first experiment ("type 1"), another type ("type 2") was used. Keeping all other variables the same as in the first experiment, a very good mechanical connection between the two thermoplastic bodies was obtained. The data are shown in table 1 below. In fig. 5a, a Scanning Electron Microscope (SEM) picture is shown, which demonstrates that at a magnification of 650 x, no boundaries can be discerned between thermoplastic bodies for the example with type 2 adhesive. In fig. 5, the upper 3 is connected to the mid-sole 2 in the same way as schematically depicted in fig. 2.

This clearly shows that by choosing the temperature such that (T)_HM+T_SUB) (T2 is equal to or higher than_M-10 ℃), a mechanically strong (or very high) connection can be obtained simply for various hot-melt adhesives, without having to rely on specific organic binding molecules, primers or complex hot-cold cycles.

TABLE 1 Strength of mechanical joints Using various Hot melt Adhesives

Hot meltingBody applying deviceAdding	Glue stickCombination of Chinese herbsAgent for treating cancer	Medicine for treating chronic hepatitis BEffect of (1)Of the hourLoad (N/inch)	Note thatMedicine for treating chronic gastritis
				ASide wall	Type (B) 1	49.1	-
ASide wall	Type (B) 1	47.3	-
				Two sides	Type (B) 1	40.6	-
Two sides	Type (B) 1	44.0
				Two sides	Type (B) 1	n.a.	BubbleFoamCrushing deviceCrack (crack) *
Two sides	Type (B) 2	98.2	-
				Two sides	Type (B) 2	n.a.	BubbleFoamCrushing deviceCrack (crack) *
Two sides	Type (B) 2	n.a.	BubbleFoamCrushing deviceCrack (crack) *

Foam collapse means that the bond strength is stronger than the inherent tear strength of the thermoplastic foam.

The above experiments were also carried out using a thermoplastic body consisting of a foamed composition comprising TPU. Similar results are obtained and therefore a connection with high mechanical strength is provided.

Claims

1. Shoe comprising a sole made of thermoplastic material, said sole being adhered to an upper with a hot melt adhesive applied between said sole and said upper, characterized in that said hot melt adhesive is fused to said thermoplastic material.

2. Shoe according to claim 1, wherein the sole comprises a foamed composition comprising 70 to 99 wt. -% of a thermoplastic copolyester elastomer, based on the total amount of the foamed composition.

3. Shoe according to claim 2, wherein the foaming composition comprises 70 to 99 wt. -% of a thermoplastic copolyester elastomer and 1 to 30 wt. -% of a plasticizer, based on the total amount of the foaming composition.

4. A shoe as set forth in claim 2 or 3 wherein the thermoplastic copolyester elastomer comprises a hard segment constructed from polyester repeat units derived from at least one aliphatic diol and at least one aromatic dicarboxylic acid or ester thereof and a soft segment selected from the group of aliphatic polyethers, aliphatic polyesters, aliphatic polycarbonates, dimerized fatty acids and dimerized fatty diols, and combinations thereof.

5. The shoe of claim 4, wherein the hard segments are selected from the group consisting of ethylene terephthalate (PET), propylene terephthalate (PPT), butylene terephthalate (PBT), polyethylene dibenzoate, polyethylene naphthalate (PEN), polybutylene dibenzoate, polybutylene naphthalate, polypropylene dibenzoate and polypropylene naphthalate, and combinations thereof, and the soft segments are selected from the group consisting of aliphatic polyethers, aliphatic polyesters, aliphatic polycarbonates, dimerized fatty acids and dimerized fatty diols, and combinations thereof.

6. The shoe of claim 5, wherein the hard segments are selected from PBT or PET and the soft segments are selected from the group consisting of polybutylene adipate (PBA), polyethylene oxide (PEO), polypropylene oxide (PPO), Polytetrahydrofuran (PTMO), PEO-PPO-PEO, and combinations thereof.

7. Shoe according to any of the previous claims, wherein said upper comprises a layer of textile material adjacent to said sole.

8. The shoe of claim 7, wherein the textile material comprises polymer yarns.

9. The shoe of claim 8, wherein the polymer yarn comprises a polyester polymer.

10. The shoe of any of the preceding claims, wherein said hot melt adhesive comprises a polymer selected from the group consisting of: (co) polyurethanes, (co) polycarbonates, (co) polyesters, (co) polyamides, (co) poly (ester-amides), mixtures thereof and/or copolymers thereof.

11. The shoe of claim 10, wherein said hot melt adhesive comprises (co) polyester.

12. Shoe according to any of the previous claims, wherein said hot-melt adhesive is semi-crystalline, preferably having a melting enthalpy comprised between 1 and 80J/g.

13. A method of assembling a workpiece comprising a first body mechanically connected to a second body by adhering the first body to a surface of the second body and a second body having a melting temperature T_MThe second body of thermoplastic material of (a), the method comprising:

heating the hot melt adhesive to a temperature T_HMSo as to soften it;

-heating the second body to bring the thermoplastic material below T_MSurface temperature T of_SUB；

-applying a heated hot melt adhesive to a surface of the heated second body;

-applying the first body to the second body to form the workpiece;

-cooling the workpiece to harden the hot melt adhesive;

14. Method according to claim 13, characterized in that the temperature is chosen such that (T) is_HM+T_SUB) [ 2 ] and T_MThe degree of the phase difference is selected from the group consisting of-10, -9, -8, -7, -6, -5, -4, -3, -2, -1, 0, +1, +2, +3, +4, +5, +6, +7, +8, +9, +10, +11, +12. +13, +14, +15, +16, +17, +18, +19, or +20 ℃.

15. Method according to any one of claims 13 or 14, characterized in that the second body is heated to obtain a temperature T of the thermoplastic material_SUBRatio T_MUp to X deg.C, X is selected from the group consisting of 100, 90, 80, 70, 60, 55, 50, 45, 40, 35, and 30.

16. A method according to any one of claims 13 to 15, wherein the second body is heated in its entirety.

17. A workpiece obtainable by the method according to any one of claims 13 to 16.