Modified wood-plastic thermoplastic polyurethane elastomer blending material and preparation method thereof

Abstract

The invention belongs to the field of composite materials, and provides a modified wood-plastic thermoplastic polyurethane elastomer blending material which comprises a thermoplastic polyurethane elastomer, plant powder and a compatilizer, the mass ratio of the plant powder to the TPU is (0.05-40): (60-99.5); the compatilizer is an isocyanate-terminated polyurethane hot melt adhesive, and the use amount of the compatilizer is 2%-10% of the total mass of the TPU and the plant powder. By adopting the compatilizer, the appearance of the wood-plastic blended material is more diversified, the dispersity of the wood filler in the thermoplastic polyurethane is improved, and the strength of the blended material is further improved.

Description

Technical Field

[0001] The invention belongs to the field of composite materials and relates to a modified wood-plastic thermoplastic polyurethane elastomer blend material and a preparation method thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Thermoplastic polyurethane elastomer (TPU) is a polymer composed of flexible segments and rigid hard segments. It has rubber elasticity at low temperatures and can be plasticized at elevated temperatures. TPU has excellent performance, excellent mechanical properties of high strength, high wear resistance, and high flexibility, and is resistant to oil, solvents, and chemicals. In addition, it has excellent ozone resistance, has little irritation to skin contact, and has good anti-allergic properties. It is used in substrates or casings in the 3C electronics field, has good feel and elasticity, and plays a good collision buffering and protective role for electronic equipment such as mobile phones, speakers, watches, VR, etc.

[0004] As people pay more and more attention to environmental protection and recyclable materials, the popularity of bio-based recyclable materials is increasing year by year. Among them, wood-plastic materials are one of the most popular bio-based materials. Wood-plastic materials not only have the characteristics of natural plants, but also can make polymer materials present the appearance of plant texture, and the content of bio-based materials can be arbitrarily adjusted, which is both beautiful and practical. Wood-plastic materials have the advantages of anti-ultraviolet, anti-insect, acid and alkali resistance, easy processing, and recyclability. They have been widely used in packaging materials, handicrafts, daily necessities, toys, home appliances, industry, automobiles, electronic products, sports goods and other fields.

[0005] Wood plastic composite material is a low-carbon, environmentally friendly, recyclable material. It has a wide range of plant sources, is cheap, and is a renewable resource. The use of this material can reduce the use of oil and reduce the consumption of wood resources.

[0006] In the preparation of wood-plastic composite materials, since natural plant-based raw materials have extremely strong polarity and hydrophilicity, while polymer materials are non-polar and non-hydrophilic, there are problems of poor compatibility and low interfacial adhesion between plant-based materials and polymer materials. Therefore, when polar plant-based materials and non-polar polymer materials are blended, problems such as poor dispersion, reduced mechanical properties of materials, and shear degradation of bio-based materials due to poor dispersion will occur.

[0007] Patent CN110682636A discloses an elastic surface co-extruded wood-plastic profile and a preparation method thereof. The polyethylene used in the patent is a non-polar substance and has poor compatibility with its polar substance components, so the material has a problem of poor dispersion.

[0008] Patent CN 116082823A discloses a highly dispersed wood-plastic thermoplastic polyurethane elastomer material and a preparation method thereof. In the patent, a strongly polar branched polyolefin is mixed with a non-polar branched polyolefin through a compatibilizer to improve the compatibility of the wood filler and the polymer. However, the addition of such polyolefin to the thermoplastic polyurethane will make the final blended material opaque. In the embodiment, more than 20% of polyolefin is added to increase the compatibility, so that the tensile strength of the final product is up to 7.3 MPa, which is significantly lower than the normal tensile strength of the substrate Shore 85A of more than 30 MPa.

[0009] It can be seen that the existing wood-plastic material preparation technology has the problems of poor product appearance, opacity, and poor dispersion resulting in a serious decrease in product tensile strength. Summary of the invention

[0010] In order to solve the above problems, the present invention provides a modified wood-plastic thermoplastic polyurethane elastomer blend material and a preparation method thereof, which makes the appearance of the wood-plastic blend material more diverse, improves the dispersibility of the wood filler in the thermoplastic polyurethane and thus improves the strength of the blend material.

[0011] In order to achieve the above object, the present invention adopts the following technical solution:

[0012] The first aspect of the present invention provides a modified wood-plastic thermoplastic polyurethane elastomer blend material, comprising: a thermoplastic polyurethane elastomer, plant powder, and a compatibilizer;

[0013] The mass ratio of the plant powder to TPU is 0.05-40:60-99.5;

[0014] The compatibilizer is an isocyanate-terminated polyurethane hot melt adhesive, and the usage amount is 2%-10% of the total mass of TPU and plant powder.

[0015] In some embodiments, the functionality of the polyol used in the isocyanate-terminated polyurethane hot melt adhesive is 2, and the molecular weight of the polyol is 1000 to 4000 g / mol;

[0016] In some embodiments, the polyol is selected from at least one of polyester polyol and polyether polyol;

[0017] Further, the polyester polyol is selected from the polycondensate of adipic acid and one or more of ethylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, diethylene glycol, neopentyl glycol, 1,6-hexanediol, trimethylolpropane, and glycerol;

[0018] Furthermore, the polyether polyol is selected from at least one of polytetramethylene glycol and polyoxypropylene glycol;

[0019] Preferably, the molecular weight of the polyol is 1000-2000 g / mol. The excellent effect of selecting a polyol within this molecular weight range is that the corresponding polyurethane hot melt adhesive has low viscosity and is easier to disperse.

[0020] In some embodiments, the chain extender of the polyurethane hot melt adhesive is a small molecule diol;

[0021] Preferably, the chain extender of the polyurethane hot melt adhesive is selected from at least one of ethylene glycol, butanediol, 1,6-hexanediol, and 2-methyl-1,3-propanediol.

[0022] In some embodiments, the isocyanate of the isocyanate-terminated polyurethane hot melt adhesive is selected from at least one of toluene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and p-phenylene diisocyanate.

[0023] In some embodiments, in the isocyanate-terminated polyurethane hot melt adhesive, the molar ratio (R value) of isocyanate groups to hydroxyl groups in the oligomer polyol is greater than 1:1 and not greater than 3:1.

[0024] In some embodiments, the thermoplastic polyurethane elastomer is at least one of a polyester thermoplastic polyurethane elastomer, a polyether thermoplastic polyurethane elastomer, a polycarbonate thermoplastic polyurethane elastomer and a polycaprolactone thermoplastic polyurethane elastomer.

[0025] Preferably, it is polyester type thermoplastic polyurethane elastomer and / or polyether type thermoplastic polyurethane elastomer;

[0026] Preferably, the hardness of the thermoplastic polyurethane elastomer is Shore A65-Shore D80, and more preferably, it is a polyester TPU of Shore A75-Shore D65.

[0027] In some embodiments, the plant powder is processed from leftover scraps and sawdust collected from a wood processing plant;

[0028] Or, the raw material of the plant powder is at least one selected from the powder of plant skin, plant root, plant stem, plant leaf, fruit shell, fruit peel, and fruit core;

[0029] Or, the raw material of the plant powder is selected from one or more of powders of bark, trunk, leaves, rice husk, straw, and nut shell;

[0030] Or, the thermal degradation temperature of the plant powder under nitrogen atmosphere is ≥190°C, or ≥220°C;

[0031] Or, the particle size of the plant powder is 1-2000 μm, preferably 50-500 μm;

[0032] Alternatively, the plant powder has a water content of 0-5%, preferably 0-1%, based on the total mass of the plant powder.

[0033] The second aspect of the present invention provides a method for preparing a modified wood-plastic thermoplastic polyurethane elastomer blend material, comprising:

[0034] The plant powder and TPU are mixed evenly and extruded using a twin-screw extruder;

[0035] At the first exhaust port of the twin-screw extruder, the compatibilizer is fed into the reactive twin-screw extruder through a hot melt adhesive machine, and then pelletized underwater and dried to obtain a modified wood-plastic thermoplastic polyurethane elastomer blended material.

[0036] In some embodiments, the temperature of the twin-screw or single-screw extrusion is 120-200° C., the screw speed is 100-400 rpm, and the screw aspect ratio is 40-50:1.

[0037] The third aspect of the present invention provides the use of the modified wood-plastic thermoplastic polyurethane elastomer blend material in the fields of packaging materials, handicrafts, daily necessities, toys, home appliances, industry, automobiles, electronic products and sporting goods.

[0038] Beneficial Effects of the Invention

[0039] (1) In the present invention, in the preparation of the wood-plastic composite material, the natural plant-based raw material has extremely strong polarity and hydrophilicity and contains a large number of hydroxyl groups (-OH); the compatibilizer used in the present invention is a -NCO-terminated polyurethane hot melt adhesive, which is a reactive compatibilizer. TPU is generally hydroxyl (-OH)-terminated, and a large number of hydroxyl groups (-OH) contained in the natural plant-based raw material can react with the -NCO group of the compatibilizer, which can, on the one hand, extend the TPU molecular chain, increase the molecular weight, and improve the strength of TPU; on the other hand, the natural plant-based raw material and the TPU molecular chain can be connected together, thereby improving the compatibility of the materials, and transforming the two materials from an incompatible state to a state with high compatibility. In addition, the polyurethane hot melt adhesive and TPU are components with similar polarity, which have little effect on the transparency of TPU, so that the modified wood-plastic thermoplastic polyurethane elastomer blend material has high strength and transparency.

[0040] The modified wood-plastic thermoplastic polyurethane elastomer blend material, the TPU is preferably a Shore A75-Shore D65 polyester TPU. The polyester TPU has more polar groups, which can make the blend material form more hydrogen bonds. The TPU with a hardness of Shore A75-Shore D65 has a faster molding speed and good mechanical properties and feel, which makes up for the adverse effects of the introduction of natural plant-based raw materials such as hard feel, poor rebound, and low strength.

[0041] (2) The present invention also provides a modified wood-plastic thermoplastic polyurethane elastomer blend material prepared by the above preparation method. The compatibilizer used in the present invention is a -NCO-terminated polyurethane hot melt adhesive, which is a reactive compatibilizer, and the polyurethane hot melt adhesive and TPU are components with similar polarity, which has little effect on the transparency of TPU, so that the modified wood-plastic thermoplastic polyurethane elastomer blend material has higher strength and transparency than other wood-plastic blend materials.

[0042] (3) The preparation method of the present invention is simple, practical and easy to promote. DETAILED DESCRIPTION

[0043] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0044] The present invention will be further described in detail below in conjunction with specific embodiments. It should be noted that the specific embodiments are intended to explain the present invention rather than to limit it.

[0045] The polyester or polyether thermoplastic polyurethane elastomers were purchased from Mirathane E85, a polyester thermoplastic polyurethane elastomer, and Mirathane M85, a polyether thermoplastic polyurethane elastomer, from Mirathane New Materials Co., Ltd.

[0046] The compatibilizer was purchased from the polyether polyurethane hot melt adhesive R1408 of Meirui New Materials Co., Ltd., with an R value of 1.8:1 and a molecular weight of the polyether polyol of 100 g / mol.

[0047] The plant powder was purchased from Yantai Wangyuan Wood Processing Co., Ltd. as poplar powder (particle size 60 mesh, mud content 0.01%, water content 0.2%).

[0048] Example 1

[0049] The amounts of thermoplastic polyurethane elastomer, plant powder and polyurethane hot melt adhesive are shown in Table 1.

[0050] The preparation steps of the blended material are:

[0051] (1) Drying of raw materials: Place thermoplastic polyurethane elastomer and plant powder in a dehumidification drying silo at a silo temperature of 25 degrees, stir for 2 hours, and dehumidification regeneration temperature of 120 degrees. Mix evenly.

[0052] 2. Co-extrusion: The mixed and dried thermoplastic polyurethane elastomer / plant powder raw material is poured into the twin-screw extruder from the first exhaust port (the 6th zone of the twin-screw extruder) through the pouring port, and the polyurethane hot melt adhesive is fed into the twin-screw extruder at a uniform speed in proportion through a hot melt adhesive machine (heating temperature is 60°C); the rotation speed is 250rpm, the reaction zone temperature of the twin screw is 210°C, and the temperature of the cooling zone is 100°C. The extruded material is cut and granulated underwater, and the granulation water temperature is controlled at 30±3°C. The obtained granules are dried at a drying temperature of 70°C and a drying time of 2h.

[0053] Example 2

[0054] The amounts of thermoplastic polyurethane elastomer, plant powder and polyurethane hot melt adhesive are shown in Table 1.

[0055] The preparation method is the same as Example 1.

[0056] Example 3

[0057] The amounts of thermoplastic polyurethane elastomer, plant powder and polyurethane hot melt adhesive are shown in Table 1.

[0058] The preparation method is the same as Example 1.

[0059] Example 4

[0060] The amounts of thermoplastic polyurethane elastomer, plant powder and polyurethane hot melt adhesive are shown in Table 1.

[0061] The preparation method is the same as Example 1.

[0062] Example 5

[0063] The amounts of thermoplastic polyurethane elastomer, plant powder and polyurethane hot melt adhesive are shown in Table 1.

[0064] The preparation method is the same as Example 1.

[0065] Example 6

[0066] The amounts of thermoplastic polyurethane elastomer, plant powder and polyurethane hot melt adhesive are shown in Table 1.

[0067] The preparation method is the same as Example 1.

[0068] Example 7

[0069] The amounts of thermoplastic polyurethane elastomer, plant powder and polyurethane hot melt adhesive are shown in Table 1.

[0070] The preparation method is the same as that of Example 1.

[0071] Example 8

[0072] The amounts of thermoplastic polyurethane elastomer, plant powder and polyurethane hot melt adhesive are shown in Table 1.

[0073] The preparation method is the same as that of Example 1.

[0074] Comparative Example 1

[0075] The difference from Example 3 is that no compatibilizer polyurethane hot melt adhesive is added.

[0076] Comparative Example 2

[0077] The difference from Example 3 is that no poplar powder is added.

[0078] Comparative Example 3

[0079] The difference from Example 3 is that poplar powder and compatibilizer polyurethane hot melt adhesive are not added.

[0080] Comparative Example 4

[0081] In this comparative example 4, the product with the best comprehensive performance prepared by Example 4 in patent CN 116082823A is used;

[0082] The manufacturer and particle size of the plant powder used in Example 3 of the present invention are different from those in the above-mentioned patent. The polyester thermoplastic elastomer used in the present invention is E85, and the tensile strength is the same as the raw material used in the above-mentioned patent; the final modified finished product has a tensile strength of 7.6Mpa, which is higher than 6.1Mpa of Example 4 of patent CN 116082823A.

[0083] Comparative Example 5

[0084] The difference from Example 3 is that the compatibilizer is a polyurethane hot melt adhesive that is “not terminated with isocyanate groups”.

[0085] The test results show that it basically has no effect as a compatibilizer.

[0086] The amounts of various raw materials used in the examples and comparative examples of the present invention are shown in Table 1 below.

[0087] Table 1

[0088] serial number M85 E85 Poplar powder R1408 Example 1 98％ / 2％ 5％ Example 2 92％ / 8％ 5％ Example 3 85％ / 15％ 5％ Example 4 70％ / 30％ 5％ Example 5 85％ / 15％ 2％ Example 6 85％ / 15％ 7％ Example 7 85％ / 15％ 10％ Example 8 / 85％ 15％ 5％ Comparative Example 1 85％ / 15％ / Comparative Example 2 85％ / / 5％ Comparative Example 3 100％ / / /

[0089] Table 2

[0090]

[0091]

[0092] In Table 2, the tensile strength test standard is ASTM D412-16, and the elongation at break test standard is ASTM D412-16.

[0093] From the results in Table 2, it can be seen that compared with Examples 1-8 and Comparative Example 4, the transparency and tensile strength of the blended materials prepared in this patent have obvious advantages.

[0094] Examples 1-4 show that as the poplar powder content increases, the transparency and strength of the blended material decrease.

[0095] From the comparison between Examples 1-8 and Comparative Example 1, it can be seen that the compatibilizer (polyurethane hot melt adhesive) has a significant effect on the dispersion of bio-based powder and the improvement of the compatibility of each component.

[0096] Comparison between Comparative Example 2 and Comparative Example 3 shows that adding a compatibilizer (polyurethane hot melt adhesive) can improve the tensile strength of TPU.

[0097] Comparison between Example 3 and Example 8 shows that the compatibility is more significantly improved when TPU and compatibilizer polyurethane hot melt adhesive with the same soft segment components are selected.

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A modified wood-plastic thermoplastic polyurethane elastomer blend material, characterized in that: include: Thermoplastic polyurethane elastomer, plant powder, compatibilizer; The mass ratio of the plant powder to TPU is 0.05-40:60-99.5; The compatibilizer is an isocyanate-terminated polyurethane hot melt adhesive, and the usage amount is 2%-10% of the total mass of TPU and plant powder.

2. The modified wood-plastic thermoplastic polyurethane elastomer blend material according to claim 1, characterized in that: The functionality of the polyol used in the isocyanate-terminated polyurethane hot melt adhesive is 2, and the molecular weight of the polyol is 1000 to 4000 g / mol; Or, the polyol is selected from at least one of polyester polyol and polyether polyol; Or, the polyester polyol is selected from the polycondensate of adipic acid and one or more of ethylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, diethylene glycol, neopentyl glycol, 1,6-hexanediol, trimethylolpropane, and glycerol; Or, the polyether polyol is selected from at least one of polytetramethylene polyol and polyoxypropylene polyol; Alternatively, the molecular weight of the polyol is 1000 to 2000 g / mol.

3. The modified wood-plastic thermoplastic polyurethane elastomer blend material according to claim 1, characterized in that: The chain extender of the polyurethane hot melt adhesive is a small molecule diol; Alternatively, the chain extender of the polyurethane hot melt adhesive is selected from at least one of ethylene glycol, butanediol, 1,6-hexanediol, and 2-methyl-1,3-propanediol.

4. The modified wood-plastic thermoplastic polyurethane elastomer blend material according to claim 1, characterized in that: The isocyanate of the isocyanate-terminated polyurethane hot melt adhesive is selected from at least one of toluene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and p-phenylene diisocyanate.

5. The modified wood-plastic thermoplastic polyurethane elastomer blend material according to claim 1, characterized in that: In the isocyanate-terminated polyurethane hot melt adhesive, the molar ratio of isocyanate groups to hydroxyl groups in the oligomer polyol is greater than 1:1 and not greater than 3:

1.

6. The modified wood-plastic thermoplastic polyurethane elastomer blend material according to claim 1, characterized in that: The thermoplastic polyurethane elastomer is at least one of polyester thermoplastic polyurethane elastomer, polyether thermoplastic polyurethane elastomer, polycarbonate thermoplastic polyurethane elastomer and polycaprolactone thermoplastic polyurethane elastomer.

7. The modified wood-plastic thermoplastic polyurethane elastomer blend material according to claim 1, characterized in that: The plant powder is processed from the remaining scraps and sawdust collected in the wood processing plant; Or, the raw material of the plant powder is at least one selected from the powder of plant skin, plant root, plant stem, plant leaf, fruit shell, fruit peel, and fruit core; Or, the raw material of the plant powder is selected from one or more of powders of bark, trunk, leaves, rice husk, straw, and nut shell; Or, the thermal degradation temperature of the plant powder under nitrogen atmosphere is ≥190°C, or ≥220°C; Or, the plant powder has a particle size of 1-2000 μm or 50-500 μm; Alternatively, the plant powder has a moisture content of 0-5% or 0-1%, based on the total mass of the plant powder.

8. A method for preparing a modified wood-plastic thermoplastic polyurethane elastomer blend material, characterized in that: include: The plant powder and TPU are mixed evenly and extruded using a twin-screw extruder; At the first exhaust port of the twin-screw extruder, the compatibilizer is fed into the reactive twin-screw extruder through a hot melt adhesive machine, and then pelletized underwater and dried to obtain a modified wood-plastic thermoplastic polyurethane elastomer blended material.

9. The method for preparing the modified wood-plastic thermoplastic polyurethane elastomer blend material according to claim 8, characterized in that: The temperature of twin-screw or single-screw extrusion is 120-200°C, the screw speed is 100-400rpm, and the screw aspect ratio is 40-50:

1.

10. Application of the modified wood-plastic thermoplastic polyurethane elastomer blend material according to any one of claims 1 to 8 in the fields of packaging materials, handicrafts, daily necessities, toys, home appliances, industry, automobiles, electronic products and sporting goods.

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