Biodegradable polyurethane, preparation method and application thereof, and surface treating agent

Abstract

The invention belongs to the technical field of polymers, and provides biodegradable polyurethane as well as a preparation method and application thereof and a surface treating agent. According to the biodegradable polyurethane provided by the invention, the bio-based polyester polyol, the isocyanate, the chain extender and the catalyst in a specific ratio are used as main preparation raw materials, and the structure of the isocyanate contains a five-membered ring and / or a six-membered ring, so that the isocyanate can be further used as a surface treating agent; according to the present invention, the prepared polyurethane adhesive has the good surface treatment effect on different polyurethane materials or polyurethane-like materials, can be used for treating the shoe material surface so as to achieve the excellent adhesion effect on the shoe material surface and the polyurethane adhesive, does not use the harmful solvent, and has characteristics of environmental protection, safety and high biodegradation degree.

Description

Technical Field

[0001] The present invention relates to the technical field of polymers, and more specifically, to a biodegradable polyurethane, a preparation method and an application thereof, and a surface treatment agent. Background Art

[0002] Currently, the commonly used shoe-making raw materials (or shoe materials) are generally polyurethane (PU) materials and polyvinyl chloride (PVC) materials, specifically: rigid polyurethane elastomers, TPU (thermoplastic polyurethane rubber) foaming materials, polyurethane leather, polyurethane-coated leather, rigid PVC, PVC foaming materials, PVC leather, etc. In the shoe-making process, it is generally necessary to coat a polyurethane adhesive for shoes on the surface of the shoe materials. Before coating the polyurethane adhesive for shoes, it is also necessary to use a shoe material treatment agent to pre-modify the surface of these PU and PVC shoe materials. If the surface modification is not carried out in advance and the polyurethane adhesive for shoes is directly coated, an effective bonding cannot be formed or the bonding effect cannot meet the shoe-making requirements (generally, the peeling strength between the bonded materials is required to be ≥2.5 N / mm).

[0003] The existing treatment agents on the market are mainly small-molecule polyurethanes dissolved in high-boiling solvents. Through the dissolution, swelling and etching of the surface of these materials by the high-boiling solvents, and at the same time, the groups with better affinity to the materials in the small-molecule polyurethanes penetrate into the surface layer of the shoe materials, so that a polyurethane layer that can be affinity with the polyurethane adhesive is formed on the surface of the shoe materials. This polyurethane layer and the polyurethane adhesive crystallize together during the drying process to form a bond with higher strength, so as to meet the bonding requirements. However, the shoe material treatment agents currently used on the market use a large amount of solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, N-ethylpyrrolidone, tetrahydrofuran, cyclohexanone, etc. These solvents not only have high boiling points, but also usually have high human toxicity, biological toxicity or strong irritation, causing great harm to the health of shoe-making workers and the environment. Currently, the mainstream shoe brands have prohibited the use of the above solvents, but this will sacrifice the bonding performance to a great extent, resulting in insecure bonding. In addition, organic tin compounds are usually used as catalysts in the preparation process of the current shoe material treatment agents. However, organic tin compounds cause great harm to the human body and have low safety.

[0004] Therefore, there is an urgent need to develop a shoe material surface treatment agent that can form a high-strength bond between shoe materials (such as PU, PVC, TPU, synthetic leather or foamed PU midsoles, etc.) and polyurethane adhesives, without using harmful solvents, and improve the use safety. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a biodegradable polyurethane and its preparation method and application, and a surface treatment agent. The biodegradable polyurethane provided by the present invention does not need to be prepared using harmful solvents and has high safety. For example, it can be used as a surface treatment agent to pre-treat shoe materials, and then further coated with a polyurethane adhesive. After the surface treatment agent is treated, the shoe materials (PU and / or PVC) can be highly strongly bonded to the polyurethane adhesive to form a good bond. The initial peel strength reaches 3.1-4.2N / mm, the later peel strength reaches 3.2-6.5N / mm, the peel strength after the aging test still reaches 3.1-6.4N / mm, and the peel strength after the hydrolysis test still reaches 2.8-4.2N / mm, which meets the requirements of the shoemaking field (peel strength ≥ 2.5N / mm), and the initial, later, after aging and after the hydrolysis test with the polyurethane adhesive have strong bonding, and the later durability and weather resistance are excellent.

[0006] A first aspect of the present invention provides a biodegradable polyurethane.

[0007] Specifically, a biodegradable polyurethane comprises the following preparation raw materials in parts by weight:

[0008] 100 parts of bio-based polyester polyol,

[0009] Isocyanate 15-28 parts,

[0010] Chain extender 5-10 parts;

[0011] Catalyst 0.05-0.5 parts;

[0012] The isocyanate contains a five-membered ring and / or a six-membered ring in its structure.

[0013] The present invention uses bio-based polyester polyol as a raw material for preparation. The bio-based polyester polyol has multiple hydroxyl groups and carboxyl groups, which can provide affinity and make the product biodegradable. Isocyanate connects the main chain of the product to a five-membered ring and / or a six-membered ring, thereby improving the molecular rigidity, crystallinity and compactness of the product. The biodegradable polyurethane of the present invention is further used as a shoe material treatment agent, which can well improve the adhesion between the shoe material and the polyurethane adhesive without relying on a high-boiling point solvent. In addition, the polyurethane shoe material treatment agent provided by the present invention is not only biodegradable, but also has rigid segments and flexible segments at the same time. This special structure of the polymer has rapid crystallization, strong molecular rigidity, and small molecular gaps. It can further effectively affinity materials and block the migration of various additives added during the material processing process, thereby achieving extremely high initial adhesion, later durability and weather resistance. Moreover, the present invention uses a non-organic tin catalyst, which also improves safety in use.

[0014] Preferably, the bio-based polyester polyol is polylactic acid polyol and / or castor oil polyester polyol.

[0015] Preferably, the number average molecular weight of the bio-based polyester polyol is 500 - 2000.

[0016] Preferably, the isocyanate is at least one of isophorone diisocyanate (IPDI), methylene bis(cyclohexyl) isocyanate (HMDI), and 1,5-pentane diisocyanate trimer.

[0017] Preferably, the chain extender is isophorone diamine (IPDA) and / or hydroquinone bis(β-hydroxyethyl) ether (HQEE).

[0018] Preferably, the catalyst is an organic bismuth catalyst and / or an organic zinc catalyst. The present invention does not require the use of an organic tin catalyst, which greatly improves safety.

[0019] More preferably, the organic bismuth catalyst is at least one of the organic bismuth catalyst of model AC-83, the organic bismuth catalyst of model DICNATE 425, and the organic bismuth catalyst of model Neostann U600.

[0020] Preferably, the raw materials for preparing the biodegradable polyurethane further include an organic solvent.

[0021] Preferably, calculated by weight, the raw materials for preparing the biodegradable polyurethane further include 1150 - 1350 parts of an organic solvent.

[0022] Preferably, the boiling point of the organic solvent is 80 - 100 °C, and / or the organic solvent is a ketone solvent and / or an ester solvent.

[0023] More preferably, the organic solvent is at least one of dimethyl carbonate, ethanol (EA), methyl ethyl ketone (MEK), acetone (ACE), ethyl acetate, and methyl acetate (MAC). The organic solvents used in the present invention have high safety.

[0024] The second aspect of the present invention provides a method for preparing a biodegradable polyurethane.

[0025] A method for preparing a biodegradable polyurethane includes the following steps:

[0026] First, mix the bio-based polyester polyol, the catalyst, and the isocyanate, carry out a prepolymerization reaction, and then add the chain extender to carry out a chain extension reaction to obtain the polyurethane.

[0027] Preferably, before use, the bio-based polyester polyol is dehydrated at a temperature of 80-120 °C, and / or for a time of 1-3 h.

[0028] Preferably, the temperature of the prepolymerization reaction is 80-95 °C, and / or the time of the prepolymerization reaction is 4-6 hours.

[0029] Preferably, the temperature of the chain extension reaction is 40-50 °C, and / or the time of the chain extension reaction is 1-3 h.

[0030] In the preparation process of the biodegradable polyurethane of the present invention, high temperature and high pressure are not required, and the process conditions are mild (both the prepolymerization reaction and the chain extension reaction can be carried out under normal pressure).

[0031] The third aspect of the present invention provides an application of a biodegradable polyurethane.

[0032] An application of a biodegradable polyurethane in the preparation of a polymer surface treatment agent or an adhesive.

[0033] The fourth aspect of the present invention provides a surface treatment agent.

[0034] A surface treatment agent, the preparation raw materials of the surface treatment agent include the biodegradable polyurethane.

[0035] The biodegradable polyurethane prepared by the present invention can be directly used as a surface treatment agent for shoe materials (or called a shoe material treatment agent) and used directly, or can be diluted (diluted with a diluent into treatment agents with different solid contents, such as at least one of acetone, methyl ethyl ketone, ethyl acetate, dimethyl carbonate, and methyl acetate as the diluent) and then used, or can be added to other types of treatment agents and used after mixing.

[0036] The fifth aspect of the present invention provides a surface treatment method.

[0037] A method for surface treatment of shoe materials, comprising the following steps:

[0038] (1) Take the shoe materials to be treated, first coat the surface treatment agent on at least one surface of the shoe materials to obtain the shoe materials with pretreatment completed;

[0039] (2) Then coat the polyurethane adhesive on the surface of the shoe materials with pretreatment completed.

[0040] Preferably, in step (1), the shoe materials with pretreatment completed are dried at 50-60 °C for 1-3 minutes.

[0041] Preferably, in step (2), the shoe materials coated with the polyurethane adhesive are dried at 55-65 °C for 3-5 minutes.

[0042] Preferably, in step (1), at least two shoe materials to be processed are taken. In step (2), the surfaces of at least two shoe materials coated with polyurethane adhesive are bonded, and then pressed. The surfaces of two shoe materials containing polyurethane adhesive are bonded.

[0043] Preferably, the pressure of the pressing is 2 - 5 MPa, and / or the time of the pressing is 10 - 15 seconds.

[0044] Preferably, the material of the shoe material to be processed is at least one of polyurethane (PU), polyvinyl chloride, polyurethane - polyvinyl chloride composite material, thermoplastic polyurethane elastomer (TPU), and foamed polyurethane (PU) midsole. The surface treatment agent provided by the present invention can treat shoe materials of various materials.

[0045] Preferably, the polyurethane adhesive is at least one of polyester - HDI (1,6 - hexamethylene diisocyanate) solvent - based adhesive, polyester - HDI water - based adhesive, polyester - MDI (diphenylmethane diisocyanate) solvent - based adhesive, and polyester - MDI water - based adhesive.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] The biodegradable polyurethane provided by the present invention uses specifically proportioned bio - based polyester polyol, isocyanate, chain extender, and catalyst as the main raw materials for preparation. The structure of the isocyanate contains a five - membered ring and / or a six - membered ring, and can further be used as a surface treatment agent, which has universality and can achieve good treatment effects on the surfaces of various polyurethane materials or polyurethane - like materials (hard, soft, foamed, non - foamed, oil - filled, non - oil - filled, etc.). Further used as a surface treatment agent to treat the surface of shoe materials, the initial peel strength reaches 3.1 - 4.2 N / mm, the later peel strength reaches 3.2 - 6.5 N / mm, the peel strength still reaches 3.1 - 6.4 N / mm after the aging experiment, and the peel strength still reaches 2.8 - 4.2 N / mm after the hydrolysis experiment, all meeting the requirements in the shoe - making field (peel strength ≥ 2.5 N / mm). It has strong adhesion with polyurethane adhesive in the initial stage, later stage, after aging, and after hydrolysis experiment, and has excellent durability and weather resistance in the later stage. Moreover, it does not require the use of harmful solvents, is relatively more environmentally friendly and safe, and has a higher degree of biodegradability. Description of the Drawings

[0048] Figure 1 It is a schematic diagram of the usage process of the shoe material treatment agent. Detailed Embodiments

[0049] To make the technical solution of the present invention clearer and more understandable to those skilled in the art, the following embodiments are listed for illustration. It should be noted that the following embodiments do not limit the scope of protection required by the present invention.

[0050] In the following embodiments, the raw materials, reagents or devices used can be obtained from conventional commercial channels or can be obtained by known existing methods without special instructions.

[0051] The raw materials used in the embodiments and comparative examples of the present invention:

[0052] Bio-based polyester polyol: polylactic acid polyol, manufactured by Shanghai Yiqing, model number PLA1000.

[0053] Isophorone diisocyanate (IPDI): molecular weight 222.32, manufactured by Covestro, model number Desmodur IC.

[0054] Cyclohexylmethane diisocyanate (HMDI): molecular weight 262.35, manufactured by Wanhua Chemical Group Co., Ltd.

[0055] 1,5-Pentane diisocyanate (1,5-PDI): molecular weight 154.17, manufactured by Mitsui Chemicals, model number STABiOPDI.

[0056] Chain extender: isophorone diamine, manufactured by Evonik, model number Vestamin IPD.

[0057] Catalyst: organic zinc, manufactured by DIC Corporation of Japan, model number Neostann U600.

[0058] Example 1

[0059] A biodegradable polyurethane, comprising the preparation raw materials shown in Table 1 below.

[0060] The preparation method of the above biodegradable polyurethane comprises the following steps:

[0061] (1) First, the bio-based polyester polyol is dehydrated under reduced pressure in a reaction kettle at 100 °C for 2 h, and the stirring rate of the reaction kettle is 70 rpm. The organic zinc (catalyst) is pre-diluted with 100 times of dimethyl carbonate (the mass of dimethyl carbonate is 100 times that of the catalyst), and then put into the kettle. The solvent dimethyl carbonate is added, the stirring rate is 70 rpm, the temperature is adjusted and controlled at 90 °C, isocyanate IPDI is added, and stirring is continued for 15 min. The stirring rate is adjusted to 50 rpm, and the temperature is maintained at 90 °C for reflux reaction for 6 h. Then it is cooled to 45 °C and left to age for 12 h (no heat preservation is required during the aging process, and it is naturally cooled to room temperature);

[0062] (2) Methyl acetate (MAC) was added to the above-aged reaction solution, and the mixture was heated to 45 °C and stirred at 70 rpm for 30 min. Then, a chain extender (IPDA) was added, and isopropyl alcohol and absolute ethanol were also added. The mixture was continuously kept at 45 °C and stirred at 70 rpm for 2 h to complete the polymerization process, obtaining a polyurethane solution with a solid content of 10% and an isocyanate reaction rate of over 99.9%.

[0063] Example 2

[0064] A biodegradable polyurethane, which is different from Example 1 in the types and amounts of the preparation raw materials, as shown in Table 1 below.

[0065] Example 3

[0066] A biodegradable polyurethane, which is different from Example 1 in the types and amounts of the preparation raw materials, as shown in Table 1 below.

[0067] Comparative Example 1

[0068] A polyurethane, which is different from Example 1 in the types and amounts of the preparation raw materials, as shown in Table 1 below.

[0069] Comparative Example 2

[0070] A polyurethane, which is different from Example 1 in the types and amounts of the preparation raw materials, as shown in Table 1 below.

[0071] Comparative Example 3

[0072] A polyurethane was purchased from Zhuhai Zetao Adhesive Products Co., Ltd., with the model number P-206F.

[0073] Comparative Example 4

[0074] A polyurethane was purchased from Zhuhai Zetao Adhesive Products Co., Ltd., with the model number P-209FJ.

[0075] Comparative Example 5

[0076] A polyurethane, which is different from Example 1 in that the amount of IPDI was increased to 30 parts.

[0077] Comparative Example 6

[0078] A polyurethane, which is different from Example 1 in that the amount of IPDI was reduced to 17 parts.

[0079] The components and their amounts of each example and comparative example are shown in the following table:

[0080] Table 1 Components and amounts of each example and comparative example (parts by weight)

[0081]

[0082] Product effect test

[0083] Take TPU, synthetic leather, and foamed PU midsole as the shoe materials to be processed respectively, cut out multiple test pieces with exactly the same shape. First, use the polyurethanes of Example 1 and Comparative Examples 3-6 as surface treatment agents to pre-treat the shoe materials to be processed respectively. After coating on the surface of the shoe materials, dry at 55±5°C for 2-3 minutes; then coat polyurethane adhesive (produced by Zhuhai Zetao Adhesive Products Co., Ltd., model U-248F), dry at 60±5°C for 3-5 minutes; then complete the lamination of the test pieces within 1 minute and press at a pressure of 3.5±0.5 MPa (laminate the adhesive sides of the two shoe materials) for 10-15 seconds. The specific process is as Figure 1 shown (where the materials of Shoe Materials 1 and 2 are the same), and then conduct performance tests on the test pieces.

[0084] Peel strength test method: The peel strength test method in "GB / T19340-2014 Adhesives for Shoes and Luggage", with slightly changed conditions. The initial test is within 5 minutes, and the later test is after 24 hours.

[0085] The peel strength after aging experiment and the peel strength after hydrolysis experiment are tested in the same way as above. The difference is that the placement conditions after the test pieces are made are different. Refer to the hydrolysis resistance test method in "GB / T 30779-2014 Waterborne Polyurethane Adhesives for Shoes" to set the placement conditions. The specific conditions are slightly different, as shown in the following table.

[0086] Table 2 Test on the treatment effects of different surface treatment agents

[0087]

[0088]

[0089] Note: In the test of the adhesive, if the adherend is damaged during peeling, it means that the strength at the bonded joint is greater than the cohesive strength of the material, which is the best bonding state. Therefore, in the above table, "synthetic leather damaged" and "midsole damaged" indicate high bonding strength.

[0090] As can be seen from the above table, for the shoe materials treated with the surface treatment agent of the present invention, the initial peel strength reaches 3.1-4.2 N / mm, the later peel strength reaches 3.2-6.5 N / mm, the peel strength after aging experiment still reaches 3.1-6.4 N / mm, and the peel strength after hydrolysis experiment still reaches 2.8-4.2 N / mm, all meeting the requirements in the shoe-making field (peel strength ≥ 2.5 N / mm). The bonding strength with the polyurethane adhesive is strong in the initial stage, later stage, after aging, and after hydrolysis experiment, and the durability and weather resistance in the later stage are excellent.

[0091] Using foamed polyurethane materials (foamed PU midsole and E-TPU, commonly known as "popcorn", brand adidas) as the shoe materials to be treated, and using the polyurethane solution prepared in Example 1 as the surface treatment agent (no curing agent is required) to dip-coat the treatment agent. After drying, there is no trace, and the initial adhesion is equivalent to that of similar products on the market that contain the prohibited solvent N-ethylpyrrolidone (NEP) and require the addition of a curing agent. And because there is no need to use a curing agent, there is no problem of pot life (refer to the definition of pot life in the national standard "GBT7123.1-2015 Determination of Pot Life of Multicomponent Adhesives"), which simplifies the operation steps.

[0092] The chain extension reaction of Comparative Example 1 and Comparative Example 2 is relatively slow, there is more residual NCO in the product, and the storage stability of the product is poor, so performance tests were not carried out. Due to the reduction of the cyclic structure in the polymer, the oil control property of the foamed material or the soft material containing more processing aids decreases, which will lead to poor bonding strength.

[0093] P-206 of Comparative Example 3 contains DMF. Since DMF will react with the curing agent, the curing agent cannot be added during use. Due to the lack of curing agent, the initial peel strength, peel strength after aging and hydrolysis are poor on some materials. The initial and post-hydrolysis bonding strengths of P-209FJ in Comparative Example 4 are poor.

[0094] The amount of isocyanate in Comparative Example 5 is too much, resulting in a relatively small molecular weight of the prepolymer. After chain extension, the content of the hard segment of the polyurethane is too high, with high hardness and excessive brittleness. As a treatment agent, it has a large difference in physical properties from the subsequent glue and poor compatibility, resulting in a decrease in adhesion.

[0095] The amount of isocyanate in Comparative Example 6 is too small, resulting in a relatively large molecular weight of the prepolymer. After chain extension, the content of the hard segment of the polyurethane is too low and the crystallization rate is slow, resulting in a decrease in the initial adhesion.

Claims

1. A polyurethane, characterized in that According to weight parts, the preparation includes the following raw materials: 100 parts of bio-based polyester polyol, Isocyanate 15-28 parts, Chain extender 5-10 parts, Catalyst 0.05-0.5 parts; The isocyanate contains a five-membered ring and / or a six-membered ring in its structure.

2. The polyurethane according to claim 1, characterized in that The bio-based polyester polyol is polylactic acid polyol and / or castor oil polyester polyol.

3. The polyurethane according to claim 1, characterized in that The isocyanate is at least one of isophorone diisocyanate, methylene bis(cycloethyl)isocyanate and 1,5-pentane diisocyanate trimer.

4. The polyurethane according to claim 1, characterized in that The chain extender is isophorone diamine and / or hydroquinone bis(β-hydroxyethyl) ether.

5. The method for preparing the polyurethane according to any one of claims 1 to 4, characterized in that: The steps include: Firstly, the bio-based polyester polyol, a catalyst and an isocyanate are mixed to carry out a prepolymerization reaction, and then a chain extender is added to carry out a chain extension reaction to prepare the polyurethane.

6. The method for preparing polyurethane according to claim 5, characterized in that: The temperature of the prepolymerization reaction is 80-95° C., and / or the time of the prepolymerization reaction is 4-6 hours.

7. The method for preparing polyurethane according to claim 5, characterized in that: The temperature of the chain extension reaction is 40-50° C., and / or the time of the chain extension reaction is 1-3 hours.

8. Use of the polyurethane according to any one of claims 1 to 4 in the preparation of a polymer surface treatment agent or an adhesive.

9. A surface treatment agent, characterized in that The raw materials for preparing the surface treatment agent include the polyurethane according to any one of claims 1-4.

10. A method for surface treatment of shoe materials, characterized in that: The steps include: (1) taking a shoe material to be treated, and first applying the surface treatment agent according to claim 9 on at least one surface of the shoe material to obtain a pretreated shoe material; (2) Then, the polyurethane adhesive is coated on the surface of the pretreated shoe material.

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