High-heat-insulation EVA composite material and preparation method thereof

Abstract

The invention relates to the technical field of heat insulation materials, in particular to a high-heat-insulation EVA composite material and a preparation method thereof. The ethylene-vinyl acetate copolymer composite material comprises the following components in parts by weight: 30-85 parts of an ethylene-vinyl acetate copolymer, 0.5-1 part of an antioxidant, 1.2-2 parts of a silane coupling agent, 0.5-0.7 part of an anti-hydrolysis agent and 15-20 parts of biomass filler. By selecting the ethylene-vinyl acetate copolymer with the melt index of 5-20 g / 10 min and limiting the content of vinyl acetate in the ethylene-vinyl acetate copolymer to be 20-45 wt%, the processability and the mechanical property of the composite material can be balanced; at least one of coffee grounds, tea leaf residues, bagasse and rice hull residues is added as biomass filler, so that the mechanical property can be further improved, and meanwhile, the heat insulation performance is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal insulation materials, and in particular to a high thermal insulation EVA composite material and a preparation method thereof. Background Art

[0002] Thermal insulation materials are used to isolate the heat transfer between different temperature zones, aiming to reduce energy loss, improve material performance, and help save energy and reduce emissions. Current development covers a variety of materials such as silicate biomass fillers and foam plastics, but there is still room for further expansion. EVA (ethylene-vinyl acetate copolymer) thermal insulation materials have attracted much attention due to their multiple advantages: their excellent insulation properties can effectively block current conduction and are suitable for power equipment, electronic products and other fields; they have strong weather resistance and aging resistance, and can resist external influences such as ultraviolet rays, oxygen, humidity and high temperature; they are soft and elastic, adaptable to surfaces of different shapes, easy to install, and have significant thermal insulation effects; and they are easy to process and cut to meet diverse needs. However, research on the composite modification of EVA thermal insulation properties is still insufficient, and improving this performance will broaden its application areas. With technological advances, the performance and application prospects of EVA thermal insulation materials will be broader.

[0003] Chinese invention patent CN101880418B discloses a transparent EVA thermal insulation material and its preparation method. The method firstly mixes 100 parts of thermal insulation modifier and 1.0-5.0 parts of silane coupling agent evenly; obtains the thermal insulation modifier after surface treatment, then mixes 100 parts of ethylene-vinyl acetate copolymer, 0.2-1.5 parts of cross-linking curing agent, 0-0.3 parts of antioxidant and 1-15 parts of the thermal insulation modifier after surface treatment evenly; controls the temperature at 70-110°C. The EVA granules can be directly used as hot melt adhesive for thermal insulation devices, and can also be used to manufacture thermal insulation laminated glass interlayer, but the thermal conductivity of the thermal insulation material of the invention is still greater than 0.2W / (m·K). Summary of the invention

[0004] The first aspect of the present invention provides a high thermal insulation EVA composite material, which comprises, by weight, 30-85 parts of ethylene-vinyl acetate copolymer, 0.5-1 part of antioxidant, 1.2-2 parts of silane coupling agent, 0.5-0.7 part of anti-hydrolysis agent, and 15-20 parts of biomass filler; the thermal conductivity of the composite material is not higher than 0.2W / (m·K).

[0005] The melt index (190°C / 2.16kg) of the ethylene-vinyl acetate copolymer is 5-20g / 10min.

[0006] The present application has found that by selecting an ethylene-vinyl acetate copolymer with a melt index of 5-20g / 10min and limiting the content of vinyl acetate in the ethylene-vinyl acetate copolymer to 20-45wt%, the processing performance and mechanical properties of the composite material can be balanced. The higher the melt index, the better the fluidity of the EVA resin. Good fluidity helps to better fill the mold during processing and improve the molding efficiency and quality of the product. However, excessive fluidity will lead to a decrease in the cohesive strength of the EVA material, thereby affecting its tensile strength, tear strength and other mechanical properties. The present application can balance the hardness and rigidity of EVA by limiting the content of vinyl acetate in the ethylene-vinyl acetate copolymer, which may be due to changes in the crystallinity of the ethylene-vinyl acetate copolymer.

[0007] Preferably, the melt index of the ethylene-vinyl acetate copolymer is 5-12 g / 10 min.

[0008] The content of vinyl acetate in the ethylene-vinyl acetate copolymer is 20-45wt%.

[0009] Preferably, the content of vinyl acetate in the ethylene-vinyl acetate copolymer is 20-35 wt%.

[0010] Further preferably, the ethylene-vinyl acetate copolymer has a melt index of 9 g / 10 min and a vinyl acetate content of 28 wt %, and is purchased from Formosa Plastics Corporation with a brand name of EVA7670S.

[0011] The biomass filler includes at least one of coffee residues, tea residues, bagasse, and rice husk residues.

[0012] Preferably, the biomass filler includes at least two of coffee grounds, tea grounds, and rice husk grounds.

[0013] The present application study found that adding at least one of coffee grounds, tea grounds, bagasse, and rice husk residue as a biomass filler can further improve the mechanical properties and improve the thermal insulation performance. It may be that the main component of the biomass filler is cellulose, and the specific distribution after blending promotes the dispersibility of ethylene-vinyl acetate copolymer. At the same time, the porous structure of the biomass filler increases the free volume of ethylene-vinyl acetate copolymer and increases the pores in the composite material.

[0014] The applicant accidentally discovered that by compounding any two of coffee dregs, tea dregs, and rice husk dregs as biomass fillers, the thermal insulation performance can be further improved, and the thermal conductivity is not higher than 0.2W / (m·K). It may be that different types of biomass fillers and ethylene-vinyl acetate copolymers form a structural network of materials that interpenetrate each other, forming pores of different pore sizes inside, which effectively blocks the heat transmission channel.

[0015] The weight ratio of the ethylene-vinyl acetate copolymer to the biomass filler is (2-7):1.

[0016] Preferably, the weight ratio of the ethylene-vinyl acetate copolymer to the biomass filler is (4-7):1.

[0017] The weight ratio of the silane coupling agent to the anti-hydrolysis agent is 1:(0.2-0.9).

[0018] Preferably, the weight ratio of the silane coupling agent to the anti-hydrolysis agent is 1:(0.35-0.9).

[0019] This application study found that by limiting the weight ratio of silane coupling agent to anti-hydrolysis agent to 1: (0.2-0.9), the amount of biomass filler added can be further reduced while maintaining excellent thermal insulation performance. Silane coupling agent can form a strong chemical bond between biomass filler and organic polymer, improving the stability of the composite material, but the alkaline substances contained in the biomass filler will have a certain effect on the silane coupling agent, and the addition of anti-hydrolysis agent can protect the silane coupling agent from water damage, thereby extending the service life and effect of the silane coupling agent, helping to maintain the chemical bonding between inorganic filler and organic polymer in the composite material, and improving the comprehensive performance of the composite material.

[0020] The anti-hydrolysis agent includes a hindered aromatic carbodiimide anti-hydrolysis agent.

[0021] Preferably, the brand of the anti-hydrolysis agent includes at least one of the following: anti-hydrolysis agent 700F, anti-hydrolysis agent KSJJ-30, anti-hydrolysis agent FT-9188, and anti-hydrolysis agent AW700.

[0022] Preferably, the silane coupling agent includes at least one of the following brands: KH-550, KH-551, KH-560, KH-570, A-151, A-171.

[0023] Preferably, the antioxidant includes at least one of antioxidant 1010, antioxidant 264, antioxidant BHT, antioxidant 2246, and antioxidant 168.

[0024] The second aspect of the present invention provides a method for preparing a high thermal insulation EVA composite material, comprising the following steps: mixing the components, stirring evenly, and extruding using a twin-screw extruder to obtain a high thermal insulation EVA composite material.

[0025] The stirring speed is 1000-2000 rpm.

[0026] Preferably, the stirring rate is 1000-1500 rpm.

[0027] The extrusion temperature is 70-100° C., and the rotation speed of the twin-screw extruder is 100-300 rpm.

[0028] Preferably, the extrusion temperature is 70-90° C., and the rotation speed of the twin-screw extruder is 100-200 rpm.

[0029] Beneficial Effects

[0030] 1. By selecting an ethylene-vinyl acetate copolymer with a melt index of 5-20 g / 10 min and limiting the content of vinyl acetate in the ethylene-vinyl acetate copolymer to 20-45 wt%, the processing properties and mechanical properties of the composite material can be balanced.

[0031] 2. Adding at least one of coffee residues, tea residues, bagasse, and rice husk residues as a biomass filler can further improve the mechanical properties and improve the thermal insulation properties.

[0032] 3. By compounding any two of coffee grounds, tea grounds, and rice husk residues as biomass fillers, the thermal insulation performance can be further improved, and the thermal conductivity is not higher than 0.2 W / (m·K).

[0033] 4. By limiting the weight ratio of silane coupling agent to anti-hydrolysis agent to 1:(0.2-0.9), the amount of biomass filler added can be further reduced while maintaining excellent thermal insulation performance.

[0034] 5. The price of biomass filler in this application is lower than that of conventional filler, which effectively reduces production costs. DETAILED DESCRIPTION

[0035] Example 1

[0036] A high thermal insulation EVA composite material, which comprises, by weight, 33 parts of ethylene-vinyl acetate copolymer, 0.7 parts of antioxidant (BASF Co., Ltd., antioxidant 1010), 0.8 parts of silane coupling agent (Shanghai Yuanye Biotechnology Co., Ltd., KH-550), 0.7 parts of anti-hydrolysis agent (AW-700), and 15 parts of biomass filler.

[0037] The ethylene-vinyl acetate copolymer has a melt index of 9 g / 10 min and a vinyl acetate content of 28 wt %, and is purchased from Formosa Plastics Corporation with a brand name of EVA7670S.

[0038] The biomass filler is coffee grounds (made by a coffee machine, coffee charcoal powder extracted from coffee grounds left after roasting coffee beans).

[0039] A method for preparing a high thermal insulation EVA composite material comprises the following steps:

[0040] The raw material components were put into a stirrer and stirred evenly at a stirring speed of 1200 rpm. The obtained blend was passed through a twin-screw extruder, cooled and pelletized to obtain a composite material. The extrusion temperature was set at 85° C. and the screw speed of the twin-screw extruder was set at 200 rpm.

[0041] Example 2

[0042] A high thermal insulation EVA composite material comprises, by weight, 85 parts of ethylene-vinyl acetate copolymer, 0.8 parts of antioxidant (BASF Co., Ltd., antioxidant 1010), 0.8 parts of silane coupling agent (Shanghai Yuanye Biotechnology Co., Ltd., KH-550), 0.7 parts of anti-hydrolysis agent (AW-700), and 15 parts of biomass filler.

[0043] The ethylene-vinyl acetate copolymer has a melt index of 9 g / 10 min and a vinyl acetate content of 28 wt %, and is purchased from Formosa Plastics Corporation with a brand name of EVA7670S.

[0044] The biomass filler is coffee grounds (homemade in a coffee machine, coffee charcoal powder extracted from coffee grounds left after roasting coffee beans) and rice husk residues, with a weight ratio of 1:1.

[0045] A method for preparing a high thermal insulation EVA composite material comprises the following steps:

[0046] The raw material components were put into a stirrer and stirred evenly at a stirring speed of 1200 rpm. The obtained blend was passed through a twin-screw extruder, cooled and pelletized to obtain a composite material. The extrusion temperature was set at 85° C. and the screw speed of the twin-screw extruder was set at 200 rpm.

[0047] Example 3

[0048] A high thermal insulation EVA composite material comprises, by weight, 85 parts of ethylene-vinyl acetate copolymer, 0.8 parts of antioxidant (BASF Co., Ltd., antioxidant 1010), 1.9 parts of silane coupling agent (Shanghai Yuanye Biotechnology Co., Ltd., KH-550), 0.7 parts of anti-hydrolysis agent (AW-700), and 15 parts of biomass filler.

[0049] The ethylene-vinyl acetate copolymer has a melt index of 9 g / 10 min and a vinyl acetate content of 28 wt %, and is purchased from Formosa Plastics Corporation with a brand name of EVA7670S.

[0050] The biomass filler is tea residue.

[0051] A method for preparing a high thermal insulation EVA composite material comprises the following steps:

[0052] The raw material components were put into a stirrer and stirred evenly at a stirring speed of 1200 rpm. The obtained blend was passed through a twin-screw extruder, cooled and pelletized to obtain a composite material. The extrusion temperature was set at 85° C. and the screw speed of the twin-screw extruder was set at 200 rpm.

[0053] Comparative Example 1

[0054] An EVA composite material comprises, by weight, 85 parts of ethylene-vinyl acetate copolymer, 0.8 parts of antioxidant (BASF Co., Ltd., antioxidant 1010), 1.9 parts of silane coupling agent (Shanghai Yuanye Biotechnology Co., Ltd., KH-550), and 0.7 parts of anti-hydrolysis agent (AW-700).

[0055] The ethylene-vinyl acetate copolymer has a melt index of 9 g / 10 min and a vinyl acetate content of 28 wt %, and is purchased from Formosa Plastics Corporation with a brand name of EVA7670S.

[0056] A method for preparing an EVA composite material comprises the following steps:

[0057] The raw material components were put into a stirrer and stirred evenly at a stirring speed of 1200 rpm. The obtained blend was passed through a twin-screw extruder, cooled and pelletized to obtain a composite material. The extrusion temperature was set at 85° C. and the screw speed of the twin-screw extruder was set at 200 rpm.

[0058] Comparative Example 2

[0059] An EVA composite material comprises, by weight, 85 parts of ethylene-vinyl acetate copolymer, 0.8 parts of antioxidant (BASF Co., Ltd., antioxidant 1010), 1.9 parts of silane coupling agent (Shanghai Yuanye Biotechnology Co., Ltd., KH-550), 0.7 parts of anti-hydrolysis agent (AW-700), and 15 parts of alumina filler (Evonik Degussa, AEROXIDE AluC).

[0060] The ethylene-vinyl acetate copolymer has a melt index of 9 g / 10 min and a vinyl acetate content of 28 wt %, and is purchased from Formosa Plastics Corporation with a brand name of EVA7670S.

[0061] A method for preparing an EVA composite material comprises the following steps:

[0062] The raw material components were put into a stirrer and stirred evenly at a stirring speed of 1200 rpm. The obtained blend was passed through a twin-screw extruder, cooled and pelletized to obtain a composite material. The extrusion temperature was set at 85° C. and the screw speed of the twin-screw extruder was set at 200 rpm.

[0063] Performance Testing Methods

[0064] The composite materials prepared in the examples and comparative examples were laminated (lamination temperature: 90° C., thickness: 0.2 mm), and then the performance was tested. The test data are listed in Table 1.

[0065] Thermal conductivity: tested according to national standard GB / T 39862-2021.

[0066] Tensile strength and elongation at break: Take two 200mm×200mm uncured films and stack them. According to the lamination treatment regulations in GB / T1040.3-2006, fully cure the films (crosslinking degree above 75%, flat upper and lower surfaces, uniform thickness), and then prepare dumbbell-shaped specimens according to the 5-type specimen standard, with at least 5 specimens per group. Measure the thickness of each specimen with a thickness gauge and record it; install the dumbbell-shaped specimen on a universal material testing machine and fix it with a pneumatic clamp; perform tensile tests at a speed of 100mm / min±10mm / min according to the test steps of GB / T 1040.1-2006, measure at least 5 specimens per group, and record the maximum stress and elongation at break. Calculate the tensile strength and elongation at break of each specimen according to the formula specified in GB / T 1040.1-2006, record the values ​​of each specimen, and calculate the average tensile strength and average elongation at break of each group as the final results.

[0067] Performance test data

[0068] Table 1

[0069]

Claims

1. A high thermal insulation EVA composite material, characterized in that: The components include, by weight: 30-85 parts of ethylene-vinyl acetate copolymer, 0.5-1 parts of antioxidant, 1.2-2 parts of silane coupling agent, 0.5-0.7 parts of anti-hydrolysis agent, and 15-20 parts of biomass filler; the thermal conductivity of the composite material is not higher than 0.2W / (m·K).

2. The high thermal insulation EVA composite material according to claim 1, characterized in that: The melt index of the ethylene-vinyl acetate copolymer at 190° C. is 5-20 g / 10 min.

3. The high thermal insulation EVA composite material according to claim 2, characterized in that: The content of vinyl acetate in the ethylene-vinyl acetate copolymer is 20-45wt%.

4. The high thermal insulation EVA composite material according to claim 3, characterized in that: The biomass filler includes at least one of coffee residues, tea residues, bagasse, and rice husk residues.

5. The high thermal insulation EVA composite material according to claim 1 or 4, characterized in that: The weight ratio of the ethylene-vinyl acetate copolymer to the biomass filler is (2-7):

1.

6. The high thermal insulation EVA composite material according to claim 5, characterized in that: The weight ratio of the silane coupling agent to the anti-hydrolysis agent is 1:(0.2-0.9).

7. The high thermal insulation EVA composite material according to claim 1, characterized in that: The anti-hydrolysis agent includes a hindered aromatic carbodiimide anti-hydrolysis agent.

8. A method for preparing the high thermal insulation EVA composite material according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: mixing the components, stirring evenly, and extruding by using a twin-screw extruder to obtain a high-heat-insulating EVA composite material.

9. The method for preparing the high thermal insulation EVA composite material according to claim 8, characterized in that: The stirring speed is 1000-2000 rpm.

10. The method for preparing the high thermal insulation EVA composite material according to claim 9, characterized in that: The extrusion temperature is 70-100° C., and the rotation speed of the twin-screw extruder is 100-300 rpm.

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