Bio-based degradable leather as well as preparation method and application thereof

Abstract

The invention relates to bio-based degradable leather as well as a preparation method and application thereof. The bio-based degradable leather comprises a surface layer, a PU coating, a bonding layer and a non-woven fabric bottom layer which are sequentially arranged, the PU coating is formed by coating a composite PU coating by adopting a precise coating machine; the composite PU coating comprises the following raw materials in parts by weight: 50-80 parts of bio-based polyurethane, 10-30 parts of aliphatic TPU, 3-7 parts of color paste, 20-40 parts of water, 1-5 parts of graphene, 1-5 parts of a first chain extender, 1-3 parts of a foaming agent and 0.5-1.5 parts of an antibacterial agent. The leather disclosed by the invention not only is compatible with excellent characteristics of natural leather, but also has environment-friendly and degradable properties and good flexibility, durability, tensile strength and aging resistance, and the degradation speed of the synthetic leather is greatly improved due to the increase of the bio-based content; the middle PU coating and the bonding layer are respectively formed by adopting a precise coating matched with a multi-time drying process, so that the integrated production efficiency is higher.

Description

Technical Field

[0001] The invention relates to the technical field of artificial leather, and in particular to a bio-based degradable leather and a preparation method and application thereof. Background Art

[0002] Leather has a wide range of uses, such as furniture, luggage, and car interiors. However, the global protection of animals is increasingly strengthened, and the production of natural leather is more polluting to the environment. In order to meet the ever-increasing environmental protection requirements at home and abroad and the increasing health and safety needs of consumers, ecological synthetic leather is becoming more and more popular. Therefore, as an emerging industry with broad development prospects, the synthetic leather industry is increasingly favored by investors.

[0003] With the rapid development of polyurethane synthesis technology, polyurethane system synthetic leather materials have been widely used in various aspects of human daily life, production, national defense, etc. Since polyurethane synthetic leather itself is not biodegradable and not easy to rot, it brings a large amount of solid waste pollutants to the environment, causing serious impacts on the ecological environment and biological cycle. In-depth research on the degradability of leather, handling the contradiction between leather stability and degradability, and developing biotechnology that can improve leather degradability are of great significance to the ecological environment and the sustainable development of the future leather market. Therefore, it is urgent to develop degradable materials to solve this problem; in addition, the production of synthetic leather must undergo multiple slurry coating and drying processes to obtain the finished product. Among them, drying technology is an important link in the production process of synthetic leather. The traditional synthetic leather dry production line is designed for the coating and drying requirements of oily synthetic leather slurry, and it is difficult to adapt to the requirements of water-based ecological synthetic leather. Summary of the invention

[0004] In order to overcome the shortcomings and deficiencies in the prior art, the purpose of the present invention is to provide a bio-based degradable leather, which not only has the excellent properties of natural leather, but also has environmental protection and degradable properties, as well as good flexibility, durability, tensile strength and aging resistance. Due to the increase in the bio-based content, the degradation rate of synthetic leather is greatly improved.

[0005] Another object of the present invention is to provide a method for preparing bio-based degradable leather, which is simple to operate, convenient to control, has high production efficiency, low production cost, is suitable for large-scale production, and can prepare bio-based degradable leather with strong leather feel and can be recycled.

[0006] Another object of the present invention is to provide an application of a bio-based degradable leather, which has a high bio-based content and good degradability, and has application value in the fields of fashion, luggage, home furnishings, clothing decoration, etc.

[0007] The purpose of the present invention is achieved through the following technical scheme: a bio-based degradable leather, comprising a surface layer, a PU coating, an adhesive layer, and a non-woven fabric bottom layer arranged in sequence; the PU coating is formed by coating a composite PU coating using a precision coating machine; the composite PU coating comprises the following raw materials in parts by weight: 50-80 parts of bio-based polyurethane, 10-30 parts of aliphatic TPU, 3-7 parts of color paste, 20-40 parts of water, 1-5 parts of graphene, 1-5 parts of a first chain extender, 1-3 parts of a foaming agent, and 0.5-1.5 parts of an antibacterial agent.

[0008] The bio-based degradable leather in the present invention not only has the excellent properties of natural leather, but also has environmental protection, degradability, good flexibility, durability, tensile strength and aging resistance. Due to the increase in organic matter content, the degradation rate of synthetic leather is greatly improved. The composite PU coating has high strength and high degradation rate after film formation, and no harmful substances are produced during degradation. It is environmentally friendly, healthy and recyclable. The aliphatic TPU used is a polyether aliphatic TPU that is resistant to 180-230°C, has good yellowing resistance, and is also wear-resistant, scratch-resistant and self-repairing. At the same time, its tight molecular structure provides a large number of contacts, which can be more firmly combined with the non-woven fabric base, making it less likely for the leather to be delaminated. The introduction of graphene can strengthen and toughen the PU coating, effectively improve the wear resistance, scratch resistance, heat resistance, aging resistance, antistatic, electromagnetic shielding and flame retardancy of the PU coating coating, and improve the grade of synthetic leather. The introduction of the foaming agent can achieve stable control of the foaming of the PU coating during foaming, and obtain a PU coating with uniform foaming, so that the final leather has good comprehensive performance.

[0009] Preferably, the non-woven fabric bottom layer is made by weaving and slurry coating coconut shell fiber and PTT fiber, and the slurry used for slurry coating includes the following raw materials in parts by weight: 4-8 parts of polylactic acid, 40-60 parts of DMF, and 50-80 parts of natural bio-based extracts.

[0010] The non-woven fabric bottom layer in the present invention is made of coconut shell fiber and PTT fiber. Coconut shell fiber is a biodegradable material, the raw material is easy to obtain, and it is environmentally friendly and pollution-free. Coconut shell fiber is a material with a flexible texture, rich elasticity, and high tear resistance. The artificial leather made of it has good thermal flexibility, elasticity, and high tear resistance. The natural bio-based extract and polylactic acid used in the slurry are bio-based materials, which are biodegradable, low toxicity, and low volatility. DMF has a strong dissolving ability, so that it has the characteristics of good hydrophobicity, strong covering power, soft texture, strong hand feel, etc. in the production of non-woven fabrics with coconut shell fiber and PTT fiber. The bottom layer made of it has good flexibility, durability, high tensile strength, and high elongation.

[0011] Preferably, the natural bio-based extract is prepared by the following method:

[0012] 1) Wash, dry and grind the dry roots of dandelion rubber grass into powder;

[0013] 2) putting the treated dry root powder into a reaction kettle, adding deionized water and heating and boiling for 20-30 minutes, then performing solid-liquid separation to obtain a filter residue for later use;

[0014] 3) Add the filter residue to a reactor, then add a sulfuric acid solution with a mass concentration of 1-3%, and boil it for 1-2 hours. Then, add a sodium hydroxide solution with a mass concentration of 1-3% to make the pH value of the system 7-8, and continue boiling for 20-40 minutes. Filter the filter residue by suction and put it into an oven for drying. Then, add the dried filter residue into the extraction liquid for extraction. After the precipitated extract is dried, a natural bio-based extract is obtained.

[0015] The natural bio-based extract in the present invention is prepared by the above method, and the natural bio-based extract prepared by the above method has good mechanical properties such as tensile strength and elongation at break, and also has certain antibacterial properties. After being added to the slurry to coat the non-woven fabric, the non-woven fabric can have good mechanical properties and antibacterial properties, and will not affect the biodegradation of the non-woven fabric. After being discarded, it will not cause harm to the natural environment. In the process of preparing the natural bio-based extract by the above method, the toxicity is reduced, and the non-glue components in the dandelion rubber grass are fully utilized, so that the purity of the natural bio-based extract after the final fermentation reaches more than 97%, and the obtained natural bio-based extract has good biodegradability. The residue after pre-boiling still retains a certain antibacterial effect, and has a large specific surface area, which can effectively adsorb harmful substances. Adding it to the raw material of the slurry can further assist in improving the comprehensive performance of the non-woven fabric after coating.

[0016] Preferably, the slurry used in the bonding layer includes the following raw materials in parts by weight: 30-40 parts of water-based polyurethane resin, 50-60 parts of water, 0.1-0.5 parts of thickener, and 0.1-0.3 parts of defoamer. The preferred model of the water-based polyurethane resin is MCKT-716, the preferred thickener is water-based thickener TT-50, and the defoamer is a defoamer of model SMXP-P1 provided by Dongguan Sanmei Chemical Technology Co., Ltd.; the slurry is prepared by thickening and compounding the raw materials under stirring in a disperser to obtain a slurry with a viscosity of 1300-1500CpS / 20°C.

[0017] The slurry used in the bonding layer of the present invention has the advantages of high connection strength, instant peeling, heat dry pasting, good resin permeability, etc.

[0018] Preferably, the first chain extender is at least one of 1,3-propylene glycol, 2,2-dihydroxymethylpropionic acid, 2,2-dihydroxymethylbutyric acid, PBAT, and PBS.

[0019] The specific chain extender used as the first chain extender in the present invention has a good chain extension effect and can react with functional groups on the bio-based polyurethane chain to extend the molecular chain and increase the molecular weight, thereby improving the tear strength of the PU coating.

[0020] Preferably, the foaming agent is azodicarbonamide or a mixture containing azodicarbonamide.

[0021] Preferably, the antibacterial agent is at least one of 3-(2,3-dihydroxypropyl)-5,5-dimethylhydantoin, nano-MgO, 2,3-pyrazinedicarboxylic acid, and silver-loaded rectorite.

[0022] The antibacterial agent used in the present invention is a new type of auxiliary agent with antibacterial and bactericidal properties, which further improves the antibacterial properties of PU coatings after synergistic action with bio-based polyurethane. By adding it to PU coatings, the antibacterial and mildew-proof properties of PU coatings are greatly improved, especially the antibacterial rate against common Escherichia coli and Staphylococcus aureus reaches more than 99%; among them, the antibacterial properties of the 3-(2,3-dihydroxypropyl)-5,5-dimethylhydantoin used are also renewable, and the silver-loaded rectorite used has a very high bactericidal rate against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Aspergillus niger due to the silver ions contained, and has the advantages of good high temperature resistance and good antibacterial durability, and combined with the strong adsorption and fixation effect of rectorite itself on bacteria and molds, the leather prepared in the present invention also has good antibacterial effect and is not easy to make bacteria produce tolerance.

[0023] Preferably, the bio-based polyurethane comprises the following raw materials: 30-60 parts of polyester polyol, 20-30 parts of isocyanate compound, 1-3 parts of second chain extender, 1-3 parts of dibutyltin dilaurate, and 1-5 parts of ethyl lactate.

[0024] The bio-based polyurethane in the present invention is prepared by adopting the above raw materials, and the bio-based polyurethane prepared by using the above raw materials has good biodegradability, good mechanical strength and hydrolysis resistance; the bio-based polyurethane synthesized by using polyester polyol and isocyanate compounds as synthetic raw materials and dibutyltin laurate as a catalyst has elastic properties and excellent elongation recovery properties, and also has good biodegradability and flexibility, and the ethyl lactate used has good permeability due to its unique small molecule hydroxyl structure, which can synergistically improve the performance of the prepared bio-based polyurethane; the above bio-based polyurethane solves the problem that the traditional polyurethane resin is sticky as a foaming layer at a low modulus, thereby making the synthetic leather further prepared by using the bio-based polyurethane also soft and plump.

[0025] Preferably, the second chain extender is at least one of 1,4-butanediol, 1,3-propylene glycol, neopentyl glycol, methylpropylene glycol, 1,6-hexanediol, N-alkyldiethanolamine, and methylpropylene glycol.

[0026] Preferably, the bio-based polyurethane is prepared by the following method:

[0027] F1. Add the polyester polyol in parts by weight into a reaction kettle, add the isocyanate compound while stirring, heat to 60-80°C for reaction for 1-3h, cool to 55-60°C for insulation, and set aside;

[0028] F2. Add the second chain extender, ethyl lactate and dibutyltin dilaurate to the system of step F1 according to weight parts, stir evenly at a rate of 1000-1500 r / min, and heat to 70-80° C. for reaction for 1-3 hours to obtain bio-based polyurethane.

[0029] Preferably, the polyester polyol comprises the following raw materials: 10-20 parts of diol, 0.05-0.1 parts of catalyst, 5-10 parts of pentaerythritol, and 40-60 parts of dibasic acid.

[0030] Preferably, the polyester polyol is prepared by the following method:

[0031] A1. Add diol and dibasic acid into a reaction device according to weight, heat to 140-160°C at normal pressure for 1-3h, then introduce nitrogen and cool to 100-120°C for 2-3h.

[0032] A2. Add the polyol and the catalyst to the reaction system in step A1 according to parts by weight, mix them evenly, heat to 160-200° C. and continue stirring for 1-3 hours under nitrogen conditions, then start the vacuum pump, control the vacuum degree to 0.07-0.09 MPa, react for 2-4 hours, cool and discharge the material to obtain polyester polyol.

[0033] Preferably, the diol is at least one of aliphatic diol, ethylene glycol, 1,3-propylene glycol and neopentyl glycol.

[0034] Preferably, the catalyst is at least one of antimony trioxide and organic bismuth catalyst.

[0035] Preferably, the dibasic acid is at least one of succinic acid, sebacic acid and adipic acid.

[0036] The polyester polyol in the present invention is prepared by adopting the above raw materials and methods, and the polyester polyol prepared by the above raw materials and methods has good degradation performance. The bio-based polyurethane leather manufactured by the polyester polyol using the above diols and dibasic acids as raw materials is softer, has higher elongation, and has improved handling properties, etc., which is extremely useful in industry. In addition, as a preferred embodiment, the ester polyol from biomass resources of the present invention comes from plants and has high biodegradability. In addition, the bio-based polyurethane manufactured by the polyester polyol prepared by the above method has a linear structure and excellent color tone, so it is more widely used. The bio-based diols and bio-based dibasic acids used therein have small molecular weights, which are conducive to water and enzyme attack on polyester molecules, thereby improving biodegradability. The addition of pentaerythritol can increase the tensile strength and thermal stability of the synthetic polyester resin.

[0037] The present invention also provides a method for preparing bio-based degradable leather, comprising the following steps:

[0038] S1. Dehydrate the bio-based polyurethane and aliphatic TPU in vacuum at 80-100° C. for 20-40 min according to weight to obtain a mixture A for standby use;

[0039] S2, adding water, graphene and the first chain extender to the mixture A obtained in step S1 according to parts by weight, and continuing to heat to 70-90° C. for reaction for 1-2 hours, and finally adding the foaming agent, color paste and antibacterial agent, stirring at a speed of 700-900 rpm until uniform, and then heating to 120-150° C. for foaming to obtain a composite PU coating;

[0040] S3. With release paper as the surface layer, a precision coating machine is used to coat the composite PU coating on the surface of the release paper, and the PU coating is obtained by drying. Then, the slurry required for the bonding layer is prepared, and the slurry is coated on the PU coating to form a bonding layer. The bonding layer is then attached to the non-woven fabric base layer, and the bonding layer is dried. Finally, the whole is heated to 80-100°C for heat treatment for 1-3 minutes. A roller with irregular protrusions on the surface is used for pressing or absorbing the texture to obtain a bio-based degradable leather with three-dimensional texture.

[0041] Preferably, the oven used for drying in step S3 is divided into five isothermal zones, and the temperatures of the isothermal zones are set to 90° C., 100° C., 105° C., 110° C., and 120° C. in sequence.

[0042] The present invention adopts precision coating combined with multiple drying processes to form the intermediate PU coating and the bonding layer respectively, and has the advantages of being relatively stable and more efficient, and also avoids the problems of low drying efficiency and easy wrinkling caused by the excessive thickness of the surface layer; by dividing each drying box into zones and controlling the temperature of different isothermal zones, the drying is uniform and stable, and the drying effect is good. This synthetic leather has a four-layer structure, which effectively solves the color difference problem caused by large pattern embossing.

[0043] The present invention also provides an application of bio-based degradable leather, and the bio-based degradable leather can be applied to the fields of home sofas, car seats, clothing, shoes and hats.

[0044] The beneficial effects of the present invention are as follows: the bio-based degradable leather of the present invention not only has the excellent properties of natural leather, but also has environmental protection, degradable properties, as well as good flexibility, durability, tensile strength and aging resistance. Due to the increase in the bio-based content, the degradation rate of synthetic leather is greatly improved.

[0045] The preparation method of the bio-based degradable leather of the present invention is simple to operate, convenient to control, high in production efficiency, low in production cost, and suitable for large-scale production. The prepared bio-based degradable leather has a strong leather texture and can be recycled. DETAILED DESCRIPTION

[0046] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments, and the contents mentioned in the implementation modes are not intended to limit the present invention.

[0047] Example 1

[0048] A bio-based degradable leather comprises a surface layer, a PU coating, an adhesive layer, and a non-woven fabric bottom layer which are arranged in sequence; the PU coating is formed by coating a composite PU coating with a precision coating machine; the composite PU coating comprises the following raw materials in parts by weight: 50 parts of bio-based polyurethane, 10 parts of aliphatic TPU, 3 parts of color paste, 20 parts of water, 1 part of graphene, 1 part of a first chain extender, 1 part of a foaming agent, and 0.5 parts of an antibacterial agent.

[0049] The non-woven fabric bottom layer is made by weaving and slurry coating coconut shell fiber and PTT fiber, and the slurry used for slurry coating includes the following raw materials in parts by weight: 4 parts of polylactic acid, 40 parts of DMF, and 50 parts of natural bio-based extracts.

[0050] The natural bio-based extract is prepared by the following method:

[0051] 1) Wash, dry and grind the dry roots of dandelion rubber grass into powder;

[0052] 2) putting the treated dry root powder into a reaction kettle, adding deionized water and heating and boiling for 20 minutes, then performing solid-liquid separation to obtain a filter residue for later use;

[0053] 3) Add the filter residue to a reactor, then add a sulfuric acid solution with a mass concentration of 1%, and boil it for 2 hours. Then, add a sodium hydroxide solution with a mass concentration of 1% to make the pH value of the system 7, and continue boiling for 40 minutes. Filter the filter residue and put it into an oven for drying. Then, add the dried filter residue to the extraction liquid for extraction. After the precipitated extract is dried, a natural bio-based extract is obtained.

[0054] The slurry used in the bonding layer includes the following raw materials in parts by weight: 30 parts of water-based polyurethane resin, 50 parts of water, 0.1 parts of thickener, and 0.1 parts of defoamer. The preferred model of the water-based polyurethane resin is MCKT-716, the preferred thickener is water-based thickener TT-50, and the defoamer is a defoamer of model SMXP-P1 provided by Dongguan Sanmei Chemical Technology Co., Ltd.; the slurry is prepared by thickening and compounding the raw materials under stirring in a disperser to obtain a slurry with a viscosity of 1300CpS / 20°C.

[0055] The first chain extender is 1,3-propylene glycol, and the 1,3-propylene glycol is DuPont Susterra 1,3-propylene glycol.

[0056] The foaming agent is azodicarbonamide.

[0057] The antibacterial agent is 3-(2,3-dihydroxypropyl)-5,5-dimethylhydantoin.

[0058] The bio-based polyurethane comprises the following raw materials: 30 parts of polyester polyol, 20 parts of isocyanate compound, 1 part of second chain extender, 1-3 parts of dibutyltin dilaurate, and 1 part of ethyl lactate; the isocyanate compound is aromatic polyisocyanate.

[0059] The second chain extender is 1,4-butanediol.

[0060] The bio-based polyurethane is prepared by the following method:

[0061] F1. Add the polyester polyol in parts by weight into a reaction kettle, add the isocyanate compound while stirring, heat to 60°C for reaction for 3h, cool to 55°C for insulation, and set aside;

[0062] F2. Add the second chain extender, ethyl lactate and dibutyltin dilaurate to the system of step F1 according to weight parts, stir evenly at a rate of 1000 r / min, and heat to 70° C. for reaction for 3 hours to obtain bio-based polyurethane.

[0063] The polyester polyol comprises the following raw materials: 10 parts of diol, 0.05 parts of catalyst, 5 parts of pentaerythritol and 40 parts of dibasic acid.

[0064] The diol is an aliphatic diol.

[0065] The catalyst is antimony trioxide.

[0066] The dibasic acid is succinic acid.

[0067] The polyester polyol is prepared by the following method:

[0068] A1. Add diol and dibasic acid into a reaction device according to weight, heat to 140°C at normal pressure for 3 hours, then introduce nitrogen and cool to 100°C for 3 hours.

[0069] A2. Add the polyol and the catalyst to the reaction system in step A1 according to parts by weight, mix them evenly, heat to 160°C and continue stirring for 3 hours under nitrogen, then start the vacuum pump, control the vacuum degree to 0.07 MPa and react for 4 hours, cool and discharge the material to obtain polyester polyol.

[0070] A bio-based degradable leather is prepared by the following steps:

[0071] S1. Dehydrate the bio-based polyurethane and aliphatic TPU in vacuum at 80° C. for 40 min according to weight to obtain a mixture A for standby use;

[0072] S2. Add water, graphene and the first chain extender to the mixture A obtained in step S1 according to parts by weight, and continue to heat to 70° C. for reaction for 2 hours. Finally, add the foaming agent, color paste and antibacterial agent, stir at a speed of 700 rpm until uniform, and then heat to 150° C. for foaming to obtain a composite PU coating;

[0073] S3. With release paper as the surface layer, a precision coating machine is used to cover the composite PU coating on the surface of the release paper, and the PU coating is obtained by drying. Then, the slurry required for the bonding layer is prepared, and the slurry is coated on the PU coating to form a bonding layer. The bonding layer is then attached to the non-woven fabric base layer, and the bonding layer is dried. Finally, the whole is heated to 80°C for 3 minutes, and a roller with irregular protrusions on the surface is used for pressing or absorbing the texture to obtain a bio-based degradable leather with three-dimensional texture.

[0074] The oven used for drying in step S3 is divided into five isothermal intervals, and the temperatures in the isothermal intervals are set to 90° C., 100° C., 105° C., 110° C., and 120° C. in sequence.

[0075] Example 2

[0076] A bio-based degradable leather comprises a surface layer, a PU coating, an adhesive layer, and a non-woven fabric bottom layer which are arranged in sequence; the PU coating is formed by coating a composite PU coating with a precision coating machine; the composite PU coating comprises the following raw materials in parts by weight: 70 parts of bio-based polyurethane, 20 parts of aliphatic TPU, 5 parts of color paste, 30 parts of water, 3 parts of graphene, 3 parts of a first chain extender, 2 parts of a foaming agent, and 1.0 part of an antibacterial agent.

[0077] The non-woven fabric bottom layer is made by weaving and slurry coating coconut shell fiber and PTT fiber, and the slurry used for slurry coating includes the following raw materials in parts by weight: 6 parts of polylactic acid, 50 parts of DMF, and 70 parts of natural bio-based extracts.

[0078] The natural bio-based extract is prepared by the following method:

[0079] 1) Wash, dry and grind the dry roots of dandelion rubber grass into powder;

[0080] 2) putting the processed dry root powder into a reaction kettle, adding deionized water and heating and boiling for 25 minutes, then performing solid-liquid separation to obtain a filter residue for later use;

[0081] 3) Add the filter residue into a reactor, then add a sulfuric acid solution with a mass concentration of 2%, and boil it for 1.5 hours. Then, add a sodium hydroxide solution with a mass concentration of 2% to make the pH value of the system 7.5, and continue boiling for 30 minutes. Filter the filter residue and put it into an oven for drying. Then, add the dried filter residue into the extraction liquid for extraction. After the precipitated extract is dried, a natural bio-based extract is obtained.

[0082] The slurry used in the bonding layer includes the following raw materials in parts by weight: 35 parts of water-based polyurethane resin, 55 parts of water, 0.3 parts of thickener, and 0.2 parts of defoamer. The preferred model of the water-based polyurethane resin is MCKT-716, the preferred thickener is water-based thickener TT-50, and the defoamer is a defoamer of model SMXP-P1 provided by Dongguan Sanmei Chemical Technology Co., Ltd.; the slurry is prepared by thickening and compounding the raw materials under stirring in a disperser to obtain a slurry with a viscosity of 1400CpS / 20°C.

[0083] The first chain extender is composed of 1,3-propylene glycol, 2,2-dihydroxymethylbutyric acid and PBAT in a weight ratio of 0.8:1.0:0.5.

[0084] The foaming agent is azodicarbonamide.

[0085] The antibacterial agent is composed of 3-(2,3-dihydroxypropyl)-5,5-dimethylhydantoin, nano-MgO and silver-loaded rectorite in a weight ratio of 0.7:0.9:0.5.

[0086] The bio-based polyurethane comprises the following raw materials: 50 parts of polyester polyol, 25 parts of isocyanate compound, 2 parts of second chain extender, 2 parts of dibutyltin dilaurate, and 3 parts of ethyl lactate; the isocyanate compound is aromatic polyisocyanate.

[0087] The second chain extender is composed of 1,4-butanediol, 1,3-propylene glycol and N-alkyldiethanolamine in a weight ratio of 0.7:1.0:0.6, and the 1,3-propylene glycol is 1,3-propylene glycol of DuPont Susterra brand.

[0088] The bio-based polyurethane is prepared by the following method:

[0089] F1. Add the polyester polyol in parts by weight into a reaction kettle, add the isocyanate compound while stirring, heat to 70°C for reaction for 2h, cool to 58°C for insulation, and set aside;

[0090] F2. Add the second chain extender, ethyl lactate and dibutyltin dilaurate into the system of step F1 according to weight parts, stir evenly at a rate of 1300 r / min, and heat to 75° C. for reaction for 2 hours to obtain bio-based polyurethane.

[0091] The polyester polyol comprises the following raw materials: 15 parts of glycol, 0.08 parts of catalyst, 8 parts of pentaerythritol and 50 parts of dibasic acid.

[0092] The diol is 1,3-propylene glycol; the 1,3-propylene glycol is DuPont Susterra 1,3-propylene glycol.

[0093] The catalyst is antimony trioxide.

[0094] The dibasic acid is succinic acid.

[0095] The polyester polyol is prepared by the following method:

[0096] A1. Add diol and dibasic acid into the reaction device according to weight parts, heat to 150°C at normal pressure for 2 hours, then introduce nitrogen and cool to 110°C for 2.5 hours.

[0097] A2. Add the polyol and the catalyst to the reaction system in step A1 according to parts by weight, mix them evenly, heat to 180°C and continue stirring for 2 hours under nitrogen, then start the vacuum pump, control the vacuum degree to 0.08 MPa and react for 3 hours, cool and discharge the material to obtain polyester polyol.

[0098] A bio-based degradable leather is prepared by the following steps:

[0099] S1. Dehydrate the bio-based polyurethane and aliphatic TPU in vacuum at 90° C. for 30 min according to weight to obtain a mixture A for standby use;

[0100] S2. Add water, graphene and the first chain extender to the mixture A obtained in step S1 according to parts by weight, and continue to heat to 80° C. for reaction for 1.5 hours. Finally, add the foaming agent, color paste and antibacterial agent, stir at a speed of 800 rpm until uniform, and then heat to 140° C. for foaming to obtain a composite PU coating;

[0101] S3. With release paper as the surface layer, a precision coating machine is used to cover the composite PU coating on the surface of the release paper, and the PU coating is obtained by drying. Then, the slurry required for the bonding layer is prepared, and the slurry is coated on the PU coating to form a bonding layer. The bonding layer is then attached to the non-woven fabric base layer, and the bonding layer is dried. Finally, the whole is heated to 90°C for heat treatment for 2 minutes. A roller with irregular protrusions on the surface is used for post-processing of pressing or absorbing the texture to obtain a bio-based degradable leather with three-dimensional texture.

[0102] The oven used for drying in step S3 is divided into five isothermal intervals, and the temperatures in the isothermal intervals are set to 90° C., 100° C., 105° C., 110° C., and 120° C. in sequence.

[0103] Example 3

[0104] A bio-based degradable leather comprises a surface layer, a PU coating, an adhesive layer, and a non-woven fabric bottom layer which are arranged in sequence; the PU coating is formed by coating a composite PU coating with a precision coating machine; the composite PU coating comprises the following raw materials in parts by weight: 80 parts of bio-based polyurethane, 30 parts of aliphatic TPU, 7 parts of color paste, 40 parts of water, 5 parts of graphene, 5 parts of a first chain extender, 3 parts of a foaming agent, and 1.5 parts of an antibacterial agent.

[0105] The non-woven fabric bottom layer is made by weaving and slurry coating coconut shell fiber and PTT fiber, and the slurry used for slurry coating includes the following raw materials in parts by weight: 8 parts of polylactic acid, 60 parts of DMF, and 80 parts of natural bio-based extracts.

[0106] The natural bio-based extract is prepared by the following method:

[0107] 1) Wash, dry and grind the dry roots of dandelion rubber grass into powder;

[0108] 2) putting the treated dry root powder into a reaction kettle, adding deionized water and heating and boiling for 30 minutes, then performing solid-liquid separation to obtain a filter residue for later use;

[0109] 3) Add the filter residue to a reactor, then add a 3% sulfuric acid solution, boil it for 1 hour, then add a 3% sodium hydroxide solution to make the pH value of the system 8, continue boiling for 20 minutes, filter the filter residue and put it into an oven for drying, then add the dried filter residue into the extraction liquid for extraction, and obtain the natural bio-based extract after drying.

[0110] The slurry used in the bonding layer includes the following raw materials in parts by weight: 40 parts of water-based polyurethane resin, 60 parts of water, 0.5 parts of thickener, and 0.3 parts of defoamer. The preferred model of the water-based polyurethane resin is MCKT-716, the preferred thickener is water-based thickener TT-50, and the defoamer is a defoamer of model SMXP-P1 provided by Dongguan Sanmei Chemical Technology Co., Ltd.; the slurry is prepared by thickening and compounding the raw materials under stirring in a disperser to obtain a slurry with a viscosity of 1500CpS / 20°C.

[0111] The first chain extender is 1,3-propylene glycol.

[0112] The foaming agent is azodicarbonamide.

[0113] The antibacterial agent is nano-MgO.

[0114] The bio-based polyurethane comprises the following raw materials: 60 parts of polyester polyol, 30 parts of isocyanate compound, 3 parts of second chain extender, 3 parts of dibutyltin dilaurate, and 5 parts of ethyl lactate; the isocyanate compound is aromatic polyisocyanate.

[0115] The second chain extender is N-alkyldiethanolamine.

[0116] The bio-based polyurethane is prepared by the following method:

[0117] F1. Add the polyester polyol in parts by weight into a reaction kettle, add the isocyanate compound while stirring, heat to 80°C for reaction for 1 hour, cool to 60°C for insulation, and set aside;

[0118] F2. Add the second chain extender, ethyl lactate and dibutyltin dilaurate to the system of step F1 according to weight parts, stir evenly at a rate of 1500 r / min, and heat to 70° C. for reaction for 1 hour to obtain bio-based polyurethane.

[0119] The polyester polyol comprises the following raw materials: 20 parts of diol, 0.1 parts of catalyst, 10 parts of pentaerythritol and 60 parts of dibasic acid.

[0120] The diol is 1,3-propylene glycol.

[0121] The catalyst is antimony trioxide.

[0122] The dibasic acid is adipic acid.

[0123] The polyester polyol is prepared by the following method:

[0124] A1. Add diol and dibasic acid into the reaction device according to weight parts, heat to 160°C at normal pressure for 1 hour, then introduce nitrogen and cool to 120°C for 2 hours for standby use;

[0125] A2. Add the polyol and the catalyst to the reaction system in step A1 according to parts by weight, mix them evenly, heat to 200°C and continue stirring for 1 hour under nitrogen, then start the vacuum pump, control the vacuum degree to 0.09 MPa and react for 2 hours, cool and discharge the material to obtain polyester polyol.

[0126] A bio-based degradable leather is prepared by the following steps:

[0127] S1. Dehydrate the bio-based polyurethane and aliphatic TPU in vacuum at 100° C. for 20 min according to weight to obtain a mixture A for standby use;

[0128] S2. Add water, graphene and the first chain extender to the mixture A obtained in step S1 according to parts by weight, and continue to heat to 90° C. for reaction for 1 hour. Finally, add the foaming agent, color paste and antibacterial agent, stir at a speed of 900 rpm until uniform, and then heat to 120° C. for foaming to obtain a composite PU coating;

[0129] S3. With release paper as the surface layer, a precision coating machine is used to coat the composite PU coating on the surface of the release paper, and the PU coating is obtained by drying. Then, the slurry required for the bonding layer is prepared, and the slurry is coated on the PU coating to form a bonding layer. The bonding layer is then attached to the non-woven fabric base layer, and the bonding layer is dried. Finally, the whole is heated to 100°C for heat treatment for 1 minute. A roller with irregular protrusions on the surface is used for post-processing of pressing or absorbing the texture to obtain a bio-based degradable leather with three-dimensional texture.

[0130] The oven used for drying in step S3 is divided into five isothermal intervals, and the temperatures in the isothermal intervals are set to 90° C., 100° C., 105° C., 110° C., and 120° C. in sequence.

[0131] Example 4

[0132] A bio-based degradable leather comprises a surface layer, a PU coating, an adhesive layer, and a non-woven fabric bottom layer which are arranged in sequence; the PU coating is formed by coating a composite PU coating with a precision coating machine; the composite PU coating comprises the following raw materials in parts by weight: 60 parts of bio-based polyurethane, 10 parts of aliphatic TPU, 3 parts of color paste, 25 parts of water, 5 parts of graphene, 1 part of a first chain extender, 3 parts of a foaming agent, and 1.5 parts of an antibacterial agent.

[0133] The non-woven fabric bottom layer is made of coconut shell fiber and PTT fiber through weaving and slurry coating, and the slurry used for coating includes the following raw materials in parts by weight: 4 parts of polylactic acid, 40 parts of DMF, and 80 parts of natural bio-based extracts.

[0134] The natural bio-based extract is prepared by the following method:

[0135] 1) Wash, dry and grind the dry roots of dandelion rubber grass into powder;

[0136] 2) putting the treated dry root powder into a reaction kettle, adding deionized water and heating and boiling for 30 minutes, then performing solid-liquid separation to obtain a filter residue for later use;

[0137] 3) Add the filter residue to a reactor, then add a sulfuric acid solution with a mass concentration of 1%, and boil it for 1-2 hours. Then, add a sodium hydroxide solution with a mass concentration of 1% to make the pH value of the system 7.5, and continue boiling for 30 minutes. Filter the filter residue and put it into an oven for drying. Then, add the dried filter residue to the extraction liquid for extraction. After the precipitated extract is dried, a natural bio-based extract is obtained.

[0138] The slurry used in the bonding layer includes the following raw materials in parts by weight: 40 parts of water-based polyurethane resin, 60 parts of water, 0.5 parts of thickener, and 0.3 parts of defoamer. The preferred model of the water-based polyurethane resin is MCKT-716, the preferred thickener is water-based thickener TT-50, and the defoamer is a defoamer of model SMXP-P1 provided by Dongguan Sanmei Chemical Technology Co., Ltd.; the slurry is prepared by thickening and compounding the raw materials under stirring in a disperser to obtain a slurry with a viscosity of 1500CpS / 20°C.

[0139] The first chain extender is 1,3-propylene glycol.

[0140] The foaming agent is azodicarbonamide.

[0141] The antibacterial agent is silver-loaded rectorite.

[0142] The bio-based polyurethane comprises the following raw materials: 60 parts of polyester polyol, 20 parts of isocyanate compound, 1 part of second chain extender, 3 parts of dibutyltin dilaurate, and 5 parts of ethyl lactate.

[0143] The second chain extender is 1,3-propylene glycol.

[0144] The bio-based polyurethane is prepared by the following method:

[0145] F1. Add the polyester polyol in parts by weight into a reaction kettle, add the isocyanate compound while stirring, heat to 70°C for reaction for 3h, cool to 55°C for insulation, and set aside;

[0146] F2. Add the second chain extender, ethyl lactate and dibutyltin dilaurate into the system of step F1 according to weight parts, stir evenly at a rate of 1000 r / min, and heat to 80° C. for reaction for 2 hours to obtain bio-based polyurethane.

[0147] The polyester polyol comprises the following raw materials: 10 parts of diol, 0.05 parts of catalyst, 10 parts of pentaerythritol and 40 parts of dibasic acid.

[0148] The polyester polyol is prepared by the following method:

[0149] A1. Add diol and dibasic acid into the reaction device according to weight parts, heat to 160°C at normal pressure for reaction for 3 hours, then introduce nitrogen and cool to 100°C for further reaction for 2 hours, and set aside;

[0150] A2. According to parts by weight, add polyol and catalyst to the reaction system in step A1 and mix them evenly. Heat to 160°C and continue stirring for 3 h under nitrogen. Then start the vacuum pump and control the vacuum degree to 0.07 MPa for 4 h. Cool and discharge to obtain polyester polyol.

[0151] The diol is 1,3-propylene glycol.

[0152] The catalyst is antimony trioxide.

[0153] The dibasic acid is sebacic acid.

[0154] A bio-based degradable leather is prepared by the following steps:

[0155] S1. Dehydrate the bio-based polyurethane and aliphatic TPU in vacuum at 80° C. for 20 min according to weight to obtain a mixture A for later use;

[0156] S2. Add water, graphene and the first chain extender to the mixture A obtained in step S1 according to parts by weight, and continue to heat to 90° C. for reaction for 2 hours. Finally, add the foaming agent, color paste and antibacterial agent, stir at a speed of 700 rpm until uniform, and then heat to 150° C. for foaming to obtain a composite PU coating;

[0157] S3. With release paper as the surface layer, a precision coating machine is used to cover the composite PU coating on the surface of the release paper, and the PU coating is obtained by drying. Then, the slurry required for the bonding layer is prepared, and the slurry is coated on the PU coating to form a bonding layer. The bonding layer is then attached to the non-woven fabric base layer, and the bonding layer is dried. Finally, the whole is heated to 100°C for heat treatment for 3 minutes. A roller with irregular protrusions on the surface is used for pressing or absorbing the texture to obtain a bio-based degradable leather with three-dimensional texture.

[0158] The oven used for drying in step S3 is divided into five isothermal intervals, and the temperatures in the isothermal intervals are set to 90° C., 100° C., 105° C., 110° C., and 120° C. in sequence.

[0159] Comparative Example 1

[0160] The difference between this comparative example and the above-mentioned Example 2 is that the raw material of the composite PU coating of this comparative example uses a commercially available polyurethane resin with CAS No. 9009-54-5 instead of bio-based polyurethane. The rest of the contents of this comparative example are the same as those of Example 2 and will not be repeated here.

[0161] Comparative Example 2

[0162] The difference between this comparative example and the above-mentioned Example 2 is that the polyester polyol of the present application is replaced by the commercially available polyester polyol of Asahikawa Chemical (Suzhou) Co., Ltd. in the raw materials of the composite PU coating of this comparative example, and the remaining raw materials are mixed according to the proportions of Example 3. The rest of the contents of this comparative example are the same as those of Example 2 and will not be repeated here.

[0163] Comparative Example 3

[0164] The difference between this comparative example and the above-mentioned Example 2 is that the non-woven fabric bottom layer of this comparative example adopts the commercially available PET non-woven fabric produced by Guangzhou Yixian Non-woven Fabric Co., Ltd. The rest of the contents of this comparative example are the same as those of Example 2, and will not be repeated here.

[0165] Comparative Example 4

[0166] The difference between this comparative example and the above-mentioned embodiment 2 is that the non-woven fabric used in the bottom layer of this comparative example has not been subjected to sizing treatment. The rest of the contents of this comparative example are the same as those of embodiment 2 and will not be described again.

[0167] Comparative Example 5

[0168] The difference between this comparative example and the above-mentioned Example 2 is that no natural bio-based extract is added to the slurry used for slurry treatment of the non-woven fabric used for the bottom layer in this comparative example. The rest of the contents of this comparative example are the same as those of Example 2 and will not be repeated here.

[0169] Performance Testing

[0170] The performance of the composite PU coatings prepared in Example 2 and Comparative Examples 1-2 was tested after film formation, and the results are shown in Table 1:

[0171] Wear resistance: The wear resistance of the composite PU coatings in each embodiment and comparative example was tested with reference to GB / T1768-2006. The specific operation is as follows: Take the composite PU coatings in each embodiment 2 and comparative examples 1-2, and evenly apply them on the circular organic glass plates required by the national standard, respectively, with a coating thickness of 100 μm. After drying and forming a film, cool at room temperature, and one group is placed for one day for wear resistance test, and the other group is placed for 180 days for wear resistance test. When testing the wear resistance, first weigh the organic glass plate with an analytical balance, then put the organic glass plate on the TABER wear tester and rub it for 500 turns, then take off the organic glass plate and weigh it again. Among them, the grinding wheel speed is 72r / min, the surface load weight of the paint film is 1000g, and the average value is taken after three times. The mass difference before and after wear is the wear amount, and the size of the wear amount is used to indicate the wear resistance of the composite PU coating. Among them, the lower the wear amount, the better the wear resistance of the composite PU coating. The smaller the difference between the wear loss at 180d and 1d, the better the durable wear resistance of the composite PU coating.

[0172] Tensile strength test: refer to QB / T1646-2007 "Polyurethane synthetic leather" to test tensile strength;

[0173] Biodegradation rate: Refer to GB / T19277-2011 to test the final release of carbon dioxide after 60 days of degradation. The biodegradation rate (%) of the material is expressed by the ratio of the actual carbon dioxide release to its theoretical maximum release;

[0174] Hydrolysis resistance: Refer to QB / T4671-2014 "Test methods for artificial leather and synthetic leather - Determination of hydrolysis resistance" and use 10% sodium hydroxide to test the hydrolysis resistance for 48 hours, record the results and take the average value.

[0175] Table 1

[0176]

[0177]

[0178] It can be seen from Example 2 that the finished leather made by using the composite PU coating of the present invention has advantages such as good wear resistance and mechanical properties, as well as good biodegradability.

[0179] The performance of the nonwoven fabrics prepared in Example 2 and Comparative Examples 3-5 was tested, and the results are shown in Table 2:

[0180] Biodegradation rate (%): Tested in accordance with GB / T32366-2015 to obtain the average biodegradation rate;

[0181] Tensile strength: Use GB / T3917-1997 "Tensile test for textiles" to test tensile strength;

[0182] Antibacterial rate (Staphylococcus aureus): Tested according to QB / T4341-2012 to obtain the average antibacterial rate;

[0183] Rebound rate: tested in accordance with national standard GB / T1681-2009.

[0184] Table 2

[0185]

[0186] It can be seen from Example 2 that the non-woven fabric used in the present invention has good mechanical properties, biodegradability and good antibacterial properties, and the finished leather made therefrom has the advantages of good mechanical properties, antibacterial properties, and good biodegradability.

[0187] From the comparison between Example 2 and Comparative Examples 1-5, it can be seen that the synthetic leather prepared by the technical solution in the present application has good biodegradability, wear resistance, hydrolysis resistance, mechanical properties, and antibacterial properties, and has broad market prospects and application value.

[0188] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention may also be implemented in other ways. Any obvious replacement without departing from the concept of the present invention is within the protection scope of the present invention.

Claims

1. A bio-based degradable leather, characterized in that: It comprises a surface layer, a PU coating, a bonding layer and a non-woven fabric bottom layer which are arranged in sequence; the PU coating is formed by coating a composite PU coating with a precision coating machine; the composite PU coating comprises the following raw materials in parts by weight: 50-80 parts of bio-based polyurethane, 10-30 parts of aliphatic TPU, 3-7 parts of color paste, 20-40 parts of water, 1-5 parts of graphene, 1-5 parts of a first chain extender, 1-3 parts of a foaming agent and 0.5-1.5 parts of an antibacterial agent.

2. The bio-based degradable leather according to claim 1, characterized in that: The first chain extender is at least one of 1,3-propylene glycol, 2,2-dimethylol propionic acid, 2,2-dimethylol butyric acid, PBAT, and PBS.

3. The bio-based degradable leather according to claim 1, characterized in that: The foaming agent is azodicarbonamide or a mixture containing azodicarbonamide.

4. The bio-based degradable leather according to claim 1, characterized in that: The antibacterial agent is at least one of 3-(2,3-dihydroxypropyl)-5,5-dimethylhydantoin, nano-MgO, 2,3-pyrazine dicarboxylic acid and silver-loaded rectorite.

5. A bio-based degradable leather according to claim 1, characterized in that: The bio-based polyurethane comprises the following raw materials: 30-60 parts of polyester polyol, 20-30 parts of isocyanate compound, 1-3 parts of second chain extender, 1-3 parts of dibutyltin dilaurate, and 1-5 parts of ethyl lactate.

6. A bio-based degradable leather according to claim 5, characterized in that: The second chain extender is at least one of 1,4-butanediol, 1,3-propylene glycol, neopentyl glycol, methylpropylene glycol, 1,6-hexanediol, N-alkyldiethanolamine, and methylpropylene glycol.

7. The bio-based degradable leather according to claim 5, characterized in that: The bio-based polyurethane is prepared by the following method: F1. Add the polyester polyol in parts by weight into a reaction kettle, add the isocyanate compound while stirring, heat to 60-80°C for reaction for 1-3h, cool to 55-60°C for insulation, and set aside; F2. Add the second chain extender, ethyl lactate and dibutyltin dilaurate to the system of step F1 according to weight parts, stir evenly at a rate of 1000-1500 r / min, and heat to 70-80° C. for reaction for 1-3 hours to obtain bio-based polyurethane.

8. The bio-based degradable leather according to claim 1, characterized in that: The non-woven fabric bottom layer is made by weaving coconut shell fiber and PTT fiber and coating with pulp.

9. A method for preparing the bio-based degradable leather according to any one of claims 1 to 8, characterized in that: The steps include: S1. Dehydrate the bio-based polyurethane and aliphatic TPU in vacuum at 80-100° C. for 20-40 min according to weight to obtain a mixture A for standby use; S2, adding water, graphene and the first chain extender to the mixture A obtained in step S1 according to parts by weight, and continuing to heat to 70-90° C. for reaction for 1-2 hours, and finally adding the foaming agent, color paste and antibacterial agent, stirring at a speed of 700-900 rpm until uniform, and then heating to 120-150° C. for foaming to obtain a composite PU coating; S3. With release paper as the surface layer, a precision coating machine is used to coat the composite PU coating on the surface of the release paper, and the PU coating is obtained by drying. Then, the slurry required for the bonding layer is prepared, and the slurry is coated on the PU coating to form a bonding layer. The bonding layer is then attached to the non-woven fabric base layer, and the bonding layer is dried. Finally, the whole is heated to 80-100°C for heat treatment for 1-3 minutes. A roller with irregular protrusions on the surface is used for pressing or absorbing the texture to obtain a bio-based degradable leather with three-dimensional texture.

10. An application of the bio-based degradable leather according to any one of claims 1 to 8, characterized in that: The bio-based degradable leather can be applied to the fields of home sofas, car seats, clothing, shoes and hats.

Images