Hot-melt adhesive composition, hot-melt adhesive film and shoe stiffener

Abstract

A hot-melt adhesive composition comprises a thermoplastic polyether-ester block copolymer. Said thermoplastic polyether-ester block copolymer includes 75wt% to 85wt% polyester hard segments and 15wt% to 25wt% polyether soft segments, and said polyester hard segments are composed of benzene ring functional groups of aromatic polyester reconstituted from recycled polyester product. Said thermoplastic polyether-ester block copolymer has a hardness of

Description

[Technical Field]

[0001] This invention relates to a polyester compound composition and footwear components made from recycled polyester that can be sustainably developed, particularly to a hot melt adhesive composition, hot melt adhesive film and shoe reinforcement made from recycled polyester. [Previous Technology]

[0002] Shoe reinforcements used in the footwear industry, such as toe caps or heel counters, are made by coating a fibrous base (such as non-woven or knitted fabric) with hot melt adhesive, cutting it, bonding it to a shoe mold, and then heat-setting it. They are used to provide support for shoes and need to have a certain degree of resilience to allow the shoes to return to their original shape when deformed. Existing shoe reinforcements are usually coated with thermoplastic polyurethane-based hot melt adhesives, or they use other heterogeneous thermosetting adhesives that are different from the fibrous base material to bond with other footwear components.

[0003] Furthermore, although existing shoe reinforcement components are recyclable, when used with thermoplastic polyurethane hot melt adhesives or other heterogeneous thermosetting adhesives to manufacture shoes based on polyester fibers and other polyester materials, the presence of non-polyester heterogeneous materials makes subsequent whole-shoe recycling (also known as full shoe recycling) difficult. In addition, thermoplastic polyurethane hot melt adhesives or other heterogeneous thermosetting adhesives may also damage the quality of recycled polyester materials. Moreover, existing shoe reinforcement components, taking thermoplastic polyurethane hot melt adhesives as an example, typically involve placing the material used to form the shoe reinforcement component on a mold, coating the surface of the material with thermoplastic polyurethane hot melt adhesive, and then performing heat setting treatment at a specific temperature (usually below 90°C) to obtain a shoe reinforcement component with the desired shape. However, to avoid the aforementioned problems and use materials homologous to polyester for shoe manufacturing, the melting points of commercially available thermoplastic polyether ester elastomers manufactured from virgin materials using esterification (transesterification) polymerization are typically above 150°C. For example, the Hytrel® TPEE series sold by DuPont (typically with melting points of 150°C to 220°C) makes it impossible to perform heat setting treatment at temperatures below 90°C, or even lower, to obtain shoe reinforcement components. Furthermore, to achieve carbon reduction and sustainable development, this invention aims to provide shoe reinforcement components using polyester-based hot melt adhesive compositions. These compositions do not require additional adhesive bonding and are suitable for the heat setting temperatures of thermoplastic polyurethane-based hot melt adhesives. Therefore, polyester-based hot melt adhesive compositions can directly replace thermoplastic polyurethane-based hot melt adhesives, and shoe reinforcement components can be manufactured directly using production equipment suitable for thermoplastic polyurethane-based hot melt adhesives.

[0004] In the prior art, the relevant technologies for preparing shoe reinforcement components using thermoplastic polyurethane as hot melt adhesive are, for example, Taiwan Patent No. I510357B, and the relevant technologies for preparing shoe reinforcement components using thermoplastic polyether ester elastomer are, for example, China Mainland Patent No. 115160939A and No. 100423664C.

[0005] Although using thermoplastic polyether ester elastomer as a hot melt adhesive allows for lower temperature heat setting processing conditions (usually below 90°C), if the thermoplastic polyether ester elastomer cannot be controlled within a suitable hardness range, it will not only affect the rebound ability of the shoe reinforcement, but also require increasing or changing the thickness of the shoe reinforcement due to insufficient hardness, thus increasing the overall shoe weight. Alternatively, a hard plastic layer may need to be added to increase the hardness of the shoe reinforcement, resulting in the shoe reinforcement failing to pass the 10-cycle indentation test and failing to control the elastic loss rate of the shoe reinforcement within a low loss range. For example, Taiwan Patent No. 201410470A describes coating a molten thermoplastic polyether ester elastomer to form a resin layer and pressing the resin layer onto a polyester fiber substrate using a cooling roller to form a single layer. Taiwan Patent Nos. I499612B and I823186B describe obtaining thermoplastic polyether ester elastomers by alcoholysis and recombination of recycled polyester materials. However, since most thermoplastic polyether ester elastomers cannot provide a sufficient range of hardness and resilience, they are mostly used as non-reinforcing components.

[0006] In addition, since most thermoplastic polyether ester elastomers have a melting point greater than 110°C, it is not possible to use a processing bonding temperature or heat setting temperature below 90°C to match the processing equipment of existing shoe factories. As a result, it is necessary to use a higher processing temperature or heat setting temperature to match the melting point of the thermoplastic polyether ester elastomer. However, high-temperature processing conditions can easily lead to damage to the shoe upper.

[0007] The present invention further proposes using recycled polyester as a raw material for manufacturing shoe reinforcement components. For example, a thermoplastic polyether ester elastomer is obtained from waste polyester material, and a hot melt adhesive film is formed from the thermoplastic polyether ester elastomer and attached to the surface of the base layer. The hot melt adhesive film is then fixed to the base layer by heat setting treatment to obtain the shoe reinforcement component. The shoe reinforcement component has an elastic loss rate of less than 25% after 10 indentation tests according to the SATRA TM83 standard method. For example, a related technology in the field of footwear manufacturing is Chinese mainland patent No. 101387079A, which describes bonding a non-woven felt layer containing recycled polyester fibers to the surface of a shoe insole using a polyester adhesive. However, this shoe insole cannot provide additional elastic support and therefore cannot pass the indentation test required by the SATRA TM83 standard method.

[0008] Based on the above, how to provide a shoe reinforcement component that can be heat-set at a temperature below 90°C in conjunction with the manufacturing conditions of existing shoe factory production equipment, and still has a low elastic loss rate after 10 indentation tests, so as to obtain a shoe reinforcement component with good elastic recovery rate and appropriate resilience, while also facilitating subsequent whole shoe recycling to reduce the harm of daily consumer products to the earth and achieve the goals of carbon reduction and sustainable development, is a problem that the shoe industry needs to solve. [Summary of the Invention]

[0009] Therefore, the first object of the present invention is to provide a hot melt adhesive composition that enables shoe reinforcement to have appropriate resilience and can be obtained by low-temperature heat setting treatment, and facilitates the recycling of the entire shoe.

[0010] Therefore, the hot melt adhesive composition of the present invention comprises a thermoplastic polyether ester block copolymer.

[0011] The thermoplastic polyether ester block copolymer comprises a polyester hard segment and a polyether soft segment. The polyester hard segment is formed from a polyester product obtained by alcoholysis of recycled polyethylene terephthalate. Based on a total amount of 100 wt% of the thermoplastic polyether ester block copolymer, the content of the polyester hard segment ranges from 75 wt% to 85 wt%, the content of the polyether soft segment ranges from 15 wt% to 25 wt%, and the hardness of the thermoplastic polyether ester block copolymer ranges from 35 Shore D to 50 Shore D and the melting point ranges from 90°C to 110°C. The recycled polyethylene terephthalate in the thermoplastic polyether ester block copolymer accounts for not less than 20 wt%.

[0012] Furthermore, a second objective of the present invention is to provide a hot melt adhesive film that enables shoe reinforcements to have appropriate resilience and can be obtained by low-temperature heat setting treatment, and facilitates the recycling of the entire shoe.

[0013] Therefore, the hot melt adhesive film of the present invention is formed from the hot melt adhesive composition as described above.

[0014] Furthermore, a third objective of the present invention is to provide a shoe reinforcement having suitable resilience and obtainable by low-temperature heat setting treatment.

[0015] Thus, the shoe reinforcement of the present invention includes a base layer and a hot melt adhesive film as described above.

[0016] The hot melt adhesive film is fixed to one surface of the base layer. The shoe reinforcement exhibits an elastic loss rate of less than 25% after 10 indentation tests according to the SATRA TM83 standard method.

[0017] The advantages of this invention are as follows: By using the thermoplastic polyether ester block copolymer, especially the thermoplastic polyether ester block copolymer comprising 75wt% to 85wt% of the polyester hard segment and 15wt% to 25wt% of the polyether soft segment, and the thermoplastic polyether ester block copolymer having a hardness range of 35 Shore D to 50 Shore D and a melting point range of 90°C to 110°C, the shoe reinforcement component made from the hot melt adhesive film formed using the hot melt adhesive composition can be heat-set at a temperature below 90°C to obtain a good resilience. Furthermore, using the thermoplastic polyether ester block copolymer and the hot melt adhesive film in conjunction with a base layer to manufacture shoe reinforcement components also facilitates the recycling of the entire shoe, thereby achieving the goals of carbon reduction and sustainable development.

Implementation Method

[0018] The present invention provides a hot melt adhesive composition capable of forming a hot melt adhesive film and being used to manufacture a shoe reinforcement. The shoe reinforcement includes, but is not limited to, a toe puff and a counter.

[0019] The hot melt adhesive composition comprises a thermoplastic polyether ester block copolymer. The thermoplastic polyether ester block copolymer includes polyester hard segments and polyether soft segments. The polyester hard segments are formed from polyester products obtained by alcoholysis of recycled polyethylene terephthalate (i.e., recycled PET, abbreviated as rPET or recycled PET). Based on a total amount of 100 wt% of the thermoplastic polyether ester block copolymer, the content of the polyester hard segments ranges from 75 wt% to 85 wt%, and the content of the polyether soft segments ranges from 15 wt% to 25 wt%. The hardness of the thermoplastic polyether ester block copolymer ranges from 35 Shore D to 50 Shore D, and the melting point ranges from 90°C to 110°C. The proportion of recycled polyethylene terephthalate in the thermoplastic polyether ester block copolymer is not less than 20 wt%.

[0020] In this invention, the polyester hard segment is composed of benzene ring functional groups obtained by alcoholysis of aromatic polyester obtained from recycled polyester products. The aromatic polyester obtained from recycled polyester products refers to recycled aromatic polyester generated by reducing recycled polyester products chemically or physically, followed by depolymerization and repolymerization. This should be understood as different from virgin aromatic polyester. The recycled polyester products include, but are not limited to, recycled polymer materials, recycled PET bottles, recycled fabrics, recycled clothing, recycled fishing nets, or industrial waste. The aromatic polyester obtained by reprocessing recycled polyester products includes, but is not limited to, aromatic polyesters generated by polymerizing polyester raw materials regenerated from waste recycled PET bottles, polyaromatic polyesters generated by polymerizing polyester raw materials regenerated from polyester packaging films, aromatic polyesters generated by polymerizing polyester raw materials regenerated from waste recycled fabrics, aromatic polyesters generated by polymerizing polyester raw materials regenerated from polyester industrial waste (i.e., scraps), aromatic polyesters generated by polymerizing polyester raw materials regenerated from waste recycled clothing, aromatic polyesters generated by polymerizing polyester raw materials regenerated from post-consumer recycled fabrics, and aromatic polyesters generated by polymerizing polyester raw materials regenerated from waste recycled fishing nets, etc. Specifically, the aromatic polyester obtained by reprocessing recycled polyester products is the recycled polyethylene terephthalate.

[0021] In some embodiments of the present invention, the polyester product used to form the polyester hard segment is obtained by alcoholysis of the recycled polyethylene terephthalate and a polyol compound, and the polyester product comprises an oligomer formed by the repeating units constituting the recycled polyethylene terephthalate and the polyol compound. The repeating units constituting the recycled polyethylene terephthalate may exist in the form of monomers, dimers, small molecule polymers or combinations thereof, such as, but not limited to, low-purity bis(2-hydroxyethyl) terephthalate (Crude bis-2-hydroxyethyl terephthalate; Crude BHET), or purified high-purity, low-color polymer-grade bis(2-hydroxyethyl) terephthalate (Purified BHET). Specifically, the thermoplastic polyether ester block copolymer is formed by condensation polymerization of the polyester product and a polyether polyol. In other words, the polyester hard segment in the thermoplastic polyether ester block copolymer is formed from the polyester product, and the polyether soft segment is formed from the polyether polyol.

[0022] In some embodiments of the present invention, the polyol compound is selected from ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 1,2-hexanediol, 1,6-hexanediol, neopentanediol, 2,2-diethyl-1,3-propanediol, sorbitol, pentaerythritol, trimethylolpropane, or any combination thereof.

[0023] In some embodiments of the present invention, the polyether polyol is selected from polyethylene glycol, poly1,3-propanediol, poly1,2-propanediol, polybutanediol, poly1,6-hexanediol, poly2-methyl-1,3-propanediol, poly2-ethyl-1,2-hydroxymethyl-1,3-propanediol, polyethylene glycol monomethyl ether, polycyclohexanediol, polyneoprene glycol, polytrimethylpentanediol, polyneoprene tetrahydric alcohol, polybutylene adipate, polyethylene glycol / polypropylene glycol copolymer, polytetramethylene ether glycol, or any combination thereof, and the weight average molecular weight of the polyether polyol ranges from 400 g / mol to 8000 g / mol.

[0024] It should be noted that the present invention uses recycled polyethylene terephthalate and polyol compounds as raw materials to obtain the polyester product, and then uses the polyester product and the polyether polyol to undergo a condensation polymerization reaction to form a copolymer with a block structure. Compared with the conventional copolymer with a random structure (i.e., polyethylene terephthalate) formed by using dicarboxylic acid compounds and polyol compounds as raw materials and undergoing esterification and condensation polymerization reactions, such as Taiwan Patent Publication TW202409138A, there are obvious differences in structure between the two.

[0025] In this invention, in order to give the hot melt adhesive film appropriate hardness and the shoe reinforcement appropriate resilience, the content of the polyester hard segment in the thermoplastic polyether ester block copolymer is controlled within the range of 75wt% to 85wt%, and the content of the polyether soft segment is controlled within the range of 15wt% to 25wt%. When the content of the polyester hard segment is less than 75wt% (equivalent to the content of the polyether soft segment being greater than 25wt%), the hardness of the thermoplastic polyether ester block copolymer is less than 35 Shore D, so that the hardness of the hot melt adhesive film is too soft, causing the shoe reinforcement to be unable to maintain the required shape during heat setting. When the content of the polyester hard segment is greater than 85 wt% (equivalent to the content of the polyether soft segment being less than 15 wt%), the hardness of the thermoplastic polyether ester block copolymer is greater than 50 Shore D, resulting in insufficient resilience of the shoe reinforcement, and the melting point of the thermoplastic polyether ester block copolymer is greater than 110°C, the hot melt adhesive film cannot be heat-set at a temperature below 90°C to obtain the shoe reinforcement.

[0026] In this invention, to ensure the shoe reinforcement has appropriate resilience, the hardness of the thermoplastic polyether ester block copolymer is controlled within the range of 35 Shore D to 50 Shore D. When the hardness of the thermoplastic polyether ester block copolymer is less than 35 Shore D, the hot melt adhesive film is too soft, making it impossible to maintain the required shape of the shoe reinforcement during heat setting. When the hardness of the thermoplastic polyether ester block copolymer is greater than 50 Shore D, the shoe reinforcement is too hard, resulting in insufficient resilience.

[0027] In this invention, to meet the production process conditions of the existing footwear industry, the melting point range of the thermoplastic polyether ester block copolymer is controlled between 90°C and 110°C. When the melting point of the thermoplastic polyether ester block copolymer is less than 90°C, the hot melt adhesive film is in a molten state when heat-set at temperatures below 90°C, causing it to stick to the mold and become unprocessable. When the melting point of the thermoplastic polyether ester block copolymer is greater than 110°C, the hot melt adhesive film cannot be heat-set at temperatures below 90°C to obtain the shoe reinforcement.

[0028] In this invention, "the proportion of recycled polyethylene terephthalate in the thermoplastic polyether ester block copolymer" refers to the proportion of recycled polyethylene terephthalate derived from recycled materials in the thermoplastic polyether ester block copolymer. In this invention, the proportion of recycled polyethylene terephthalate in the thermoplastic polyether ester block copolymer is controlled to be not less than 20 wt%, thereby complying with the Global Recycled Standard (GRS).

[0029] In some embodiments of the present invention, in order to maintain a basic hardness of 35 Shore D to 50 Shore D in the thermoplastic polyether ester block copolymer and to include a certain amount of recycled material in the hot melt adhesive composition, the proportion of recycled polyethylene terephthalate in the thermoplastic polyether ester block copolymer ranges from 20 wt% to 65 wt%. In some embodiments of the present invention, in order to maintain a basic hardness of 35 Shore D to 50 Shore D in the thermoplastic polyether ester block copolymer and to further increase the amount of recycled material used, the proportion of recycled polyethylene terephthalate in the thermoplastic polyether ester block copolymer ranges from 50 wt% to 65 wt%.

[0030] In some embodiments of the present invention, the hot melt adhesive composition further comprises a polyester filler, which is present in particulate form and has an average particle size of less than 1 mm. Based on a total amount of 100 wt% of the hot melt adhesive composition, the content of the polyester filler ranges from 0 wt% to less than 50 wt%. That is, in some embodiments of the present invention, the hot melt adhesive composition may be the thermoplastic polyether ester block copolymer, or the hot melt adhesive composition may be composed of the thermoplastic polyether ester block copolymer and the polyester filler.

[0031] In some embodiments of the present invention, the hot melt adhesive composition further includes polyester filler, and the content of polyester filler is greater than 0 wt% and less than 50 wt% based on the total amount of the hot melt adhesive composition being 100 wt%.

[0032] There are no particular limitations on the type of polyester filler. Any aromatic polyester made from dicarboxylic acid compounds and diol compounds, or recycled aromatic polyester, or particulate waste generated during the polyester manufacturing process, such as debris with an average particle size of less than 1 mm generated during the cutting of polyester bottle bricks, are all applicable to this invention. In some embodiments of this invention, the polyester filler is selected from at least one of crystalline polyester, semi-crystalline polyester, and amorphous polyester. In some embodiments of the present invention, the polyester filler is selected from virgin polyethylene terephthalate, recycled polyethylene terephthalate, polyethylene terephthalate, polyethylene terephthalate, polyethylene butylene terephthalate, polyethylene (terephthalate / adipic acid) ester, polyethylene 2,5-furandicarboxylate, or any combination thereof.

[0033] In this invention, the polyethylene terephthalate raw material refers to polyethylene terephthalate obtained by esterification and condensation polymerization of dicarboxylic acid compounds and diol compounds. The dicarboxylic acid compounds include, but are not limited to, terephthalic acid, isophthalic acid, sodium isophthalate-5-sulfonate, furanyl dicarboxylic acid, adipic acid, octanoic acid, sebacic acid, azelaic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, dimer acids, dimethyl adipate, dimethyl malonate, etc. The diol compounds include, but are not limited to, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,2-pentanediol, 2,4-pentanediol, 1,6-hexanediol, 1,2-hexanediol, neopentanediol, 2,2-diethyl-1,3-propanediol, 2-methyl-1,3-propanediol, etc.

[0034] The present invention also provides a hot melt adhesive film, which is formed from the hot melt adhesive composition described above.

[0035] There are no particular limitations on the formation method of the hot melt adhesive film. In some embodiments of the present invention, the hot melt adhesive film is obtained by melting and extruding the hot melt adhesive composition to form a resin layer, and then cooling the resin layer.

[0036] In some embodiments of the present invention, the proportion of recycled polyethylene terephthalate in the hot melt adhesive film is not less than 20 wt%, thereby meeting the requirements of global recycling standards. In some embodiments of the present invention, the proportion of recycled polyethylene terephthalate in the hot melt adhesive film ranges from 30 wt% to 72 wt%.

[0037] In this invention, "the proportion of recycled polyethylene terephthalate in the hot melt adhesive film" refers to the proportion of the portion of the hot melt adhesive film derived from recycled polyethylene terephthalate.

[0038] The present invention also provides a shoe reinforcement component, comprising a base layer and a hot melt adhesive film as described above. The hot melt adhesive film is fixed to a surface of the base layer. The shoe reinforcement component exhibits an elastic loss rate of less than 25% after 10 indentation tests according to the SATRA TM83 standard method.

[0039] There are no particular limitations on the type of base layer; any material suitable for making shoe materials, such as fabric or leather, is applicable to this invention. The base layer may include, but is not limited to, nonwoven fabric, knitted fabric, woven fabric, canvas, elastic mesh, natural leather, or synthetic leather. In some embodiments of this invention, the base layer is selected from polyester nonwoven fabric, polyester knitted fabric, polyester woven fabric, polyester film, and polyester leather.

[0040] In some embodiments of the present invention, the appearance shape of the shoe reinforcement corresponds to a mold according to the type of shoe reinforcement to be manufactured, and a layer composite placed on the mold is heat-set to change the appearance shape of the layer composite and make it correspond to the mold to become the shoe reinforcement. The layer composite includes the base layer and the hot melt adhesive film attached to a surface of the base layer. In a specific example of the present invention, after the hot melt adhesive composition is melt-extruded to form a resin layer, the resin layer is directly coated onto a surface of the base layer, and the resin layer is cooled to become the hot melt adhesive film attached to the base layer to obtain a layer composite. Then, according to the type of shoe reinforcement to be manufactured, the layer composite is placed on a corresponding mold for heat-setting treatment, thereby changing the appearance shape of the layer composite to correspond to the mold, and at the same time fixing the hot melt adhesive film in the layer composite to the base layer to obtain the shoe reinforcement.

[0041] In some embodiments of the present invention, in order to meet the process conditions of shoe manufacturing using thermoplastic polyurethane as the material in existing shoe manufacturing plants and to avoid high temperature damage to the resilience of the shoe reinforcement, the temperature range of the heat setting treatment is below 90°C. In a specific example of the present invention, the temperature range of the heat setting treatment is above 60°C and below 90°C.

[0042] In this invention, "the proportion of recycled polyethylene terephthalate in the shoe reinforcement" refers to the percentage of the shoe reinforcement derived from recycled polyethylene terephthalate. In some embodiments of this invention, the proportion of recycled polyethylene terephthalate in the shoe reinforcement is not less than 20 wt%, thereby complying with global recycling standards.

[0043] The present invention will be further described with reference to the following embodiments and application examples. However, it should be understood that the embodiments and application examples are only for illustrative purposes and should not be construed as limiting the implementation of the present invention.

[0044] [Examples 1 to 5 and Comparative Examples 1 to 5] Thermoplastic polyether ester block copolymer, hot melt adhesive composition and hot melt adhesive film

[0045] The thermoplastic polyether ester block copolymers of Examples 1 to 5 and Comparative Examples 1 to 2 were prepared by the following method: 1.4 mol of recycled polyethylene terephthalate (referred to as recycled PET, source: Far Eastern New Century Co., Ltd.) was mixed with a polyol compound, and 1000 ppm of isopropyl titanate was added as a catalyst. The mixture was subjected to an alcoholysis reaction at 230°C to 250°C and a nitrogen content of 2 kg for 4 to 5 hours to obtain a polyester product. Next, the above polyester product was mixed with 0.05 mol of polyether polyol, and 800 ppm of isopropyl titanate was added as a catalyst. The mixture was subjected to a condensation polymerization reaction at 240°C to 260°C and a pressure of 200 Pa to 500 Pa for 1 to 2 hours to obtain a thermoplastic polyether ester block copolymer. In Example 1, 1.4 mol of 1,4-butanediol and 2.0 mol of 1,6-hexanediol were used as the polyol compounds, and polytetramethylene ether glycol with a weight average molecular weight of 1000 g / mol was used as the polyether polyol. Examples 2 to 5, as shown in Table 1, involved changing the types of polyol compounds and / or polyether polyols. Comparative Examples 1 to 2 used 1,4-butanediol as the polyol compound and polytetramethylene ether glycol with weight average molecular weights of 1000 g / mol and 2000 g / mol, respectively, as the polyether polyols. The content of polyester hard segments, the content of polyether soft segments, hardness, melting point, melt index, and the proportion of recycled polyethylene terephthalate (referred to as recycled PET proportion) of the thermoplastic polyether ester block copolymers of Examples 1 to 5 and Comparative Examples 1 to 2 are shown in Table 1. Subsequently, the thermoplastic polyether ester block copolymers of Examples 1 to 5 and Comparative Examples 1 to 2 were selectively mixed with polyester fillers in a content range of 0 wt% to 50 wt% according to the physical property requirements, thus completing the hot melt adhesive compositions of Examples 1 to 5 and Comparative Examples 1 to 2, as shown in Table 1.

[0046] The hot melt adhesive composition of Example 1 was taken, and then molten. The molten hot melt adhesive composition was extruded through a T-die using an extruder to form a resin layer. After the resin layer cooled, a hot melt adhesive film was obtained. Examples 2 to 5 and Comparative Examples 1 to 5 were obtained in a similar manner to Example 1. The formulations of the hot melt adhesive compositions of Examples 2 to 5 and Comparative Examples 1 to 5 are shown in Table 1. Example 2 uses 70 wt% thermoplastic polyether ester block copolymer and 30 wt% recycled polyethylene terephthalate (referred to as recycled PET, as polyester filler, purchased from Far East New Century Co., Ltd.) as the hot melt adhesive composition; Example 3 uses 50 wt% thermoplastic polyether ester block copolymer and 50 wt% virgin polyethylene terephthalate (referred to as virgin PET, as polyester filler, purchased from Far East New Century Co., Ltd.) as the hot melt adhesive composition; Example 4 uses 70 wt% thermoplastic polyether ester block copolymer and 30 wt% recycled PET (as polyester filler, purchased from Far East New Century Co., Ltd.) as the hot melt adhesive composition; Example 5 uses 70 wt%... The hot melt adhesive composition consisted of 100 wt% thermoplastic polyether ester block copolymer and 30 wt% recycled PET (purchased from Far East New Century Co., Ltd. as polyester filler); Comparative Example 1 used thermoplastic polyether ester block copolymer without adding additional polyester filler, i.e., the thermoplastic polyether ester block copolymer accounted for 100 wt%, as the hot melt adhesive composition; Comparative Example 2 used thermoplastic polyether ester block copolymer without adding additional polyester filler, i.e., the thermoplastic polyether ester block copolymer accounted for 100 wt%, as the hot melt adhesive composition; Comparative Example 3 used 100 wt% commercially available thermoplastic polyether ester elastomer (brand: DuPont, model: Hytrel® 4056, melting point: 152°C, hardness: 40). Comparative Example 4 used 100 wt% of commercially available thermoplastic polyether ester elastomer (brand: DuPont, model: Hytrel® 4556, melting point: 193°C, hardness: 45; Shore D, melt index at 220°C: 7.5 g / 10 min) as the hot melt adhesive composition; Comparative Example 5 used 100 wt% of commercially available thermoplastic polyurethane (purchased from Anfeng Industrial, model: HMU-3098, melting point: 46°C, hardness: 50; Shore D, melt index at 160°C: 6.1 g / 10 min, melt index at 200°C: 24.5 g / 10 min) as the hot melt adhesive composition.

[0047] [Application Example 1] Shoe reinforcement

[0048] According to the method of preparing hot melt adhesive film in Example 1, the resin layer of Example 1 is directly coated onto the surface of a base layer (a type of polyester nonwoven fabric with a basis weight of 20 gsm, purchased from Far East New Century Co., Ltd.), and the resin layer is allowed to cool and become a hot melt adhesive film attached to the polyester nonwoven fabric to obtain a composite layer. Then, the composite layer is placed on an arched mold and heat-set at 90°C, thereby changing the appearance shape of the composite layer to correspond to the arched mold, and at the same time fixing the hot melt adhesive film in the composite layer to the base layer to obtain a shoe reinforcement part with an arched shape and a thickness of 1.0 mm.

[0049] [Application Examples 2 to 5 and Comparative Application Examples 1 to 5] Shoe Reinforcement

[0050] Application Examples 2 to 5 and Comparative Application Examples 1 to 5 are made in a manner similar to Application Example 1, the difference being that the type of hot melt adhesive film and / or the temperature of the heat setting process are changed, as shown in Tables 2 and 3. Among them, since the heat setting process temperature required for Comparative Application Examples 1 to 4 is relatively high, it is impossible to perform the heat setting process at a temperature below 90°C. Therefore, Comparative Application Examples 1 to 4 cannot obtain shoe reinforcement components.

[0051] [Evaluation Items]

[0052] Ratio of recycled polyethylene terephthalate (referred to as recycled PET ratio): The proportion of recycled PET in the thermoplastic polyether ester block copolymer and the proportion of recycled PET in the hot melt adhesive film are calculated according to the following formulas respectively.

[0053] The proportion of recycled PET in the thermoplastic polyether ester block copolymer = (weight of recycled polyethylene terephthalate × molecular weight of terephthalic acid / molecular weight of repeating unit of polyethylene terephthalate) / theoretical yield of thermoplastic polyether ester block copolymer × 100%. Wherein, the molecular weight of terephthalic acid is 166.14 g / mol, the molecular weight of repeating unit of polyethylene terephthalate is 192.2 g / mol, and the theoretical yield of thermoplastic polyether ester block copolymer = theoretical molecular weight of thermoplastic polyether ester block copolymer × mole number of recycled polyethylene terephthalate. The theoretical molecular weight of thermoplastic polyether ester block copolymer is calculated based on the type of polyol compound and polyether polyol, assuming the dicarboxylic acid compound is terephthalic acid.

[0054] When the hot melt adhesive composition is a thermoplastic polyether ester block copolymer, or when the hot melt adhesive composition includes a thermoplastic polyether ester block copolymer and a polyester filler, and the polyester filler is not a combination containing recycled polyethylene terephthalate, the proportion of recycled PET in the hot melt adhesive film = the proportion of recycled PET in the thermoplastic polyether ester block copolymer × the content ratio of the thermoplastic polyether ester block copolymer in the hot melt adhesive composition.

[0055] When the hot melt adhesive composition includes thermoplastic polyether ester block copolymer and polyester filler, and the polyester filler is a combination containing recycled polyethylene terephthalate, the proportion of recycled PET in the hot melt adhesive film = the proportion of recycled PET in the thermoplastic polyether ester block copolymer × the content ratio of thermoplastic polyether ester block copolymer in the hot melt adhesive composition + the content ratio of recycled polyethylene terephthalate as polyester filler in the hot melt adhesive composition.

[0056] Hardness of thermoplastic polyether ester block copolymers: The thermoplastic polyether ester block copolymers of Examples 1 to 5 and Comparative Examples 1 to 2 were measured using a Shore hardness tester in accordance with the standard test method of ASTM D2240 (2021) "Standard Test Methods for Rubber Properties - Hardness Tester". The results are shown in Table 1.

[0057] Melting point of thermoplastic polyether ester block copolymer: The thermoplastic polyether ester block copolymers of Examples 1 to 5 and Comparative Examples 1 to 2 were measured using a differential scanning calorimeter (brand: HITACHI, model: DSC7000X) and under test conditions of -50°C to 250°C at a rate of 10°C / min. The results are shown in Table 1.

[0058] Mel flow index of thermoplastic polyether ester block copolymers: According to the standard test method of ISO 1133 (2022) "Plastics - Determination of melt mass flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics", the melt flow index of thermoplastic polyether ester block copolymers of Examples 1 to 5 and Comparative Examples 1 to 2 was measured using a melt flow indexer (brand: High Speed ​​Rail Testing Instruments, model: GT-7100-MIB). The results are shown in Table 1.

[0059] Elasticity Loss Rate of Shoe Reinforcement: Based on the standard test method of SATRA TM83 (2018) "Measurement of Area Shape Retention and Collapse Load of Molded Toe Liner and Heel Liner Materials", shoe reinforcements for Examples 1 to 5 and Comparative Application Examples 1 to 5 were subjected to 10 indentation tests. The elastic recovery rate was calculated based on the indentation force of the 10th test and the indentation force of the 1st test. The elastic loss rate was then calculated based on this elastic recovery rate. The results are shown in Tables 2 and 3. An elastic loss rate of less than 25% indicates that the shoe reinforcement has good resilience. Elastic recovery rate (%) = (Indentation force of the 10th test / Indentation force of the 1st test) × 100% Elastic loss rate (%) = 100% - Elastic recovery rate

[0060] Table 1. Composition and content of thermoplastic polyether ester block copolymers Example Comparative example 1 2 3 4 5 1 2 Polyester hard segment source Recycled PET + Polyol Compounds Recycled PET + Polyol Compounds Recycled PET + Polyol Compounds Recycled PET + Polyol Compounds Recycled PET + Polyol Compounds Recycled PET + Polyol Compounds Recycled PET + Polyol Compounds Types of polyol compounds 1,4-Butanediol and 1,6-Hexanediol 1,4-Butanediol, ethylene glycol and 1,6-hexanediol 1,4-Butanediol, 2,2-Diethyl-1,3-propanediol and 1,6-hexanediol 1,4-Butanediol and 1,6-Hexanediol 1,4-Butanediol and 1,6-Hexanediol 1,4-Butanediol 1,4-Butanediol Content (wt%) 85 85 85 80 75 38 80 Polyether soft segments source Polyether polyols Polyether polyols Polyether polyols Polyether polyols Polyether polyols Polyether polyols Polyether polyols Types of polyether polyols 1000 g / mol polytetramethylene ether diol 1000 g / mol polytetramethylene ether diol 1000 g / mol polytetramethylene ether diol 2000 g / mol polytetramethylene ether diol 1000 g / mol polyethylene glycol 1000 g / mol polytetramethylene ether diol 2000 g / mol polytetramethylene ether diol Content (wt%) 15 15 15 20 25 62 20 hardness (shore D) 46 44 48 42 35 25 61 Melting point (°C) 103 101 104 98 94 130 200 Melt index (g / 10min) 12.3 (160℃) 38.4 (200℃) 6.1 (160℃) 22.5 (200℃) 9.3 (160℃) 31.8 (200℃) 7.3 (160℃) 24.2 (200℃) 8.4 (160℃) 30.3 (200℃) 3.3 (160℃) 13.6 (200℃) Not reached melting point The percentage (wt%) of recycled PET in thermoplastic polyether ester block copolymers 62 60 61 56 53 28 60 Polyester filler type No additions Recycled PET PET virgin material Recycled PET Recycled PET No additions No additions Amount added (wt%) 0 30 50 30 30 0 0 Recycled PET percentage (wt%) in hot melt adhesive film 62 72 30.5 69.2 67.1 28 60

[0061] Table 2. Indentation test results of shoe reinforcement components prepared using hot melt adhesive films and / or heat setting temperatures of different embodiments. Application examples 1 2 3 4 5 basal layer Polyester nonwoven fabric Polyester nonwoven fabric Polyester nonwoven fabric Polyester nonwoven fabric Polyester nonwoven fabric hot melt adhesive film Example 1 Example 2 Example 3 Example 4 Example 5 Heat setting temperature (°C) 90 90 90 60 60 Indentation force (N) 1st time 32 36 53 35 17 10th 27 33 43 27 14 After 10 compressions Elastic recovery rate (%) 84 92 81 77 82 Elasticity loss rate (%) 16 8 19 twenty three 18

[0062] Table 3. Indentation test results of shoe reinforcement components prepared using hot melt adhesive films of different comparative examples Comparison Application Examples 1 2 3 4 5 basal layer Polyester nonwoven fabric Polyester nonwoven fabric Polyester nonwoven fabric Polyester nonwoven fabric Polyester nonwoven fabric hot melt adhesive film Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Heat setting temperature (°C) 90 90 90 90 90 Indentation force (N) 1st time N / A N / A N / A N / A 58 10th N / A N / A N / A N / A 38 After 10 compressions Elastic recovery rate (%) N / A N / A N / A N / A 65 Elasticity loss rate (%) N / A N / A N / A N / A 35 Note: "N / A" indicates that heat setting cannot be performed at temperatures below 90°C, therefore no test results are available.

[0063] Referring to Tables 1 and 2, the thermoplastic polyether ester block copolymers of Examples 1 to 5 have a hardness of 35 shore D to 48 shore D, which makes them suitable for preparing shoe reinforcements with appropriate resilience. The thermoplastic polyether ester block copolymers of Examples 1 to 5 have a melting point of 94°C to 104°C, which makes them suitable for heat setting at temperatures below 90°C to obtain shoe reinforcements. Based on this, the elastic loss rate of the shoe reinforcements of Examples 1 to 5 prepared using the hot melt adhesive film of Examples 1 to 5 is only 8% to 23%, and they can also be obtained by heat setting at temperatures of 60°C to 90°C.

[0064] In contrast, comparing Application Examples 1 to 5, referring to Tables 1 and 3, the block structure of the thermoplastic polyether ester block copolymers used in Comparative Examples 1 to 2 is more regularly arranged, and their melting points are 130°C and 200°C respectively, which makes it impossible to meet the requirement of heat setting treatment below 90°C to obtain shoe reinforcement components; the commercially available thermoplastic polyether ester elastomer Hytrel® 4056 used in Comparative Example 3 has a melting point of 152°C, and the commercially available thermoplastic polyether ester elastomer Hytrel® 4556 used in Comparative Example 4 has a melting point of 193°C. Comparative Example 3 and Comparative Example 5... Comparative Example 4 is a thermoplastic polyether ester elastomer manufactured from virgin materials using esterification (transesterification) polymerization. The hard segment structure of such thermoplastic polyether ester elastomers is formed by polymerization of a single type of diacid and diol through esterification or transesterification. It is currently the commercially available thermoplastic polyether ester elastomer with the lowest melting point. However, it still cannot meet the requirement of obtaining shoe reinforcement by heat setting treatment at a temperature below 90°C. Based on this, Comparative Application Examples 1 to 4 cannot be heat set at a temperature of 90°C to obtain shoe reinforcement, and therefore cannot be used for subsequent property measurements. The shoe reinforcement in Comparative Application Example 5 is made of commercially available thermoplastic polyurethane and has an elastic loss rate of 35%. Therefore, compared with the shoe reinforcement made of commercially available thermoplastic polyurethane, the shoe reinforcement made of the thermoplastic polyether ester block copolymer of the present invention not only has a resilience no less than that of the shoe reinforcement made of commercially available thermoplastic polyurethane, but also has a superior resilience.

[0065] On the other hand, referring to Tables 1 and 2, the recycled polyethylene terephthalate (PET) content in the thermoplastic polyether ester block copolymers of Examples 1 to 5 is 53 wt% to 62 wt%, and the recycled PET content in the hot melt adhesive films of Examples 1 to 5 is 30.5 wt% to 72 wt%. Therefore, it can be seen that both the thermoplastic polyether ester block copolymer and the hot melt adhesive film of the present invention have a recycled PET content of 20 wt% or more, indicating that the present invention uses the thermoplastic polyether ester block copolymer and the hot melt adhesive film as materials to prepare shoe reinforcement components, which has the effect of reducing carbon emissions and waste. Furthermore, both the thermoplastic polyether ester block copolymer and the hot melt adhesive film of the present invention are composed of polyester. Therefore, using this thermoplastic polyether ester block copolymer and the hot melt adhesive film in conjunction with a base layer to manufacture shoe reinforcement components also contributes to the recycling of the entire shoe.

[0066] In addition, the shoe reinforcement in Application Examples 1 to 5 forms a hot melt adhesive film by directly coating a resin layer formed of a hot melt adhesive composition onto the surface of the base layer. This allows the shoe reinforcement to be bonded to other footwear components without the need for additional adhesives. Therefore, the shoe reinforcement of the present invention has the advantages of reducing the manufacturing cost of footwear products and simplifying the manufacturing process of footwear products.

[0067] In summary, the hot melt adhesive composition of the present invention, by using a thermoplastic polyether ester block copolymer, particularly the thermoplastic polyether ester block copolymer comprising 75wt% to 85wt% of the polyester hard segment and 15wt% to 25wt% of the polyether soft segment, and the thermoplastic polyether ester block copolymer having a hardness range of 35 Shore D to 50 Shore D and a melting point range of 90°C to 110°C, results in a shoe reinforcement component made from the hot melt adhesive film formed using the hot melt adhesive composition, which has good resilience and can be obtained by heat setting at a low temperature below 90°C, thus effectively achieving the purpose of the present invention. Furthermore, both the thermoplastic polyether ester block copolymer and the hot melt adhesive film of the present invention have a recycled polyethylene terephthalate content of not less than 20 wt%, and both are composed of polyester. Therefore, using the thermoplastic polyether ester block copolymer and the hot melt adhesive film in combination with the base layer to make shoe reinforcement components not only has the effect of reducing carbon emissions and waste, but also helps in the recycling of the entire shoe.

[0068] Furthermore, by using this hot melt adhesive composition, the present invention can manufacture the shoe reinforcement at a heat setting temperature below 90°C, similar to that of thermoplastic polyurethane hot melt adhesives. Therefore, the hot melt adhesive composition can indeed directly replace existing thermoplastic polyurethane hot melt adhesives. Consequently, the shoe reinforcement can be manufactured directly using production equipment suitable for thermoplastic polyurethane hot melt adhesives in conjunction with the hot melt adhesive composition of the present invention, without the need to purchase or build new production equipment. Therefore, the present invention also has the advantages of achieving carbon reduction and sustainable development.

[0069] However, the above description is only an embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the scope of the patent application and the contents of the patent specification of the present invention shall still fall within the scope of the patent of the present invention.

Claims

1. A hot melt adhesive composition comprising: a thermoplastic polyether ester block copolymer, including a polyester hard segment and a polyether soft segment, wherein the polyester hard segment is formed from a polyester product obtained by alcoholysis of recycled polyethylene terephthalate, and based on 100 wt% of the total amount of the thermoplastic polyether ester block copolymer, the content of the polyester hard segment ranges from 75 wt% to 85 wt%, the content of the polyether soft segment ranges from 15 wt% to 25 wt%, and the hardness of the thermoplastic polyether ester block copolymer ranges from 35 Shore D to 50 Shore D and the melting point ranges from 90°C to 110°C; wherein, The proportion of recycled polyethylene terephthalate in the thermoplastic polyether ester block copolymer is not less than 20 wt%.

2. The hot melt adhesive composition as claimed in claim 1, wherein, The recycled polyethylene terephthalate in this thermoplastic polyether ester block copolymer ranges from 20 wt% to 65 wt%.

3. The hot melt adhesive composition as claimed in claim 1, wherein, The polyester product is obtained by alcoholysis of the recycled polyethylene terephthalate and a polyol compound, and the thermoplastic polyether ester block copolymer is formed by condensation polymerization of the polyester product and a polyether polyol.

4. The hot melt adhesive composition as described in claim 3, wherein, The polyol compound is selected from ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 1,2-hexanediol, 1,6-hexanediol, neopentanediol, 2,2-diethyl-1,3-propanediol, sorbitol, pentaerythritol, trimethylolpropane, or any combination thereof.

5. The hot melt adhesive composition as described in claim 3, wherein, The polyether polyol is selected from polyethylene glycol, poly1,3-propanediol, poly1,2-propanediol, polybutanediol, poly1,6-hexanediol, poly2-methyl-1,3-propanediol, poly2-ethyl-1,2-hydroxymethyl-1,3-propanediol, polyethylene glycol monomethyl ether, polycyclohexanediol, polyneoprene glycol, polytrimethylpentanediol, polyneoprene tetrahydric alcohol, polybutylene adipate, polyethylene glycol / polypropylene glycol copolymer, polytetramethylene ether glycol, or any combination thereof, and the weight average molecular weight of the polyether polyol ranges from 400 g / mol to 8000 g / mol.

6. The hot melt adhesive composition as claimed in claim 1 further comprises a polyester filler, wherein the content of the polyester filler is in the range of 0 wt% and less than 50 wt% based on a total amount of 100 wt% of the hot melt adhesive composition.

7. The hot melt adhesive composition as claimed in claim 1 further comprises a polyester filler, wherein the content of the polyester filler is greater than 0 wt% and less than 50 wt% based on a total amount of 100 wt% of the hot melt adhesive composition.

8. The hot melt adhesive composition as described in any one of claims 6 to 7, wherein, The polyester filler is selected from at least one of crystalline polyester, semi-crystalline polyester and amorphous polyester.

9. The hot melt adhesive composition as described in any one of claims 6 to 7, wherein, The polyester filler is selected from virgin polyethylene terephthalate, recycled polyethylene terephthalate, polyethylene terephthalate, polyethylene terephthalate, polyethylene terephthalate, polyethylene (terephthalate / adipic acid), polyethylene 2,5-furandicarboxylate, or any combination thereof.

10. A hot melt adhesive film formed from a hot melt adhesive composition as described in any one of claims 1 to 9.

11. A shoe reinforcement comprising: a base layer; and a hot melt adhesive film as described in claim 10, fixed to a surface of the base layer; wherein, The shoe reinforcement exhibits an elasticity loss rate of less than 25% after 10 indentation tests conducted according to the SATRA TM83 standard method.

12. The shoe reinforcement as claimed in claim 11, wherein, The appearance of the shoe reinforcement corresponds to a mold according to the type of shoe reinforcement to be manufactured, and a layer of composite placed on the mold is heat-set to change the appearance of the composite and make it correspond to the mold to become the shoe reinforcement. The composite includes the base layer and the hot melt adhesive film attached to one surface of the base layer. The temperature range of the heat-setting process is below 90°C.