Light-transmitting creep-resistant polypropylene composite material as well as preparation method and application thereof

Abstract

The invention discloses a light-transmitting creep-resistant polypropylene composite material as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The light-transmitting creep-resistant polypropylene composite material comprises the following components in parts by weight: 24-51 parts of homo-polypropylene resin, 10-25 parts of polypropylene random copolymer resin, 22-35 parts of glass fibers, 2-5 parts of a compatilizer, 0.3-1 part of a transparent nucleating agent and 5-15 parts of linear low-density polyethylene, the homo-polypropylene resin, the co-polypropylene resin, the glass fiber, the transparent nucleating agent and other components are compounded, so that the tensile strength and light transmittance of the composite material can be effectively improved, the creep resistance of the composite material can be effectively improved, and the requirements of plastic products with high working environment temperature on the performance of the polypropylene composite material can be met.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a light-transmitting creep-resistant polypropylene composite material and a preparation method and application thereof. Background Art

[0002] Compared with other general thermoplastic resins, polypropylene has the advantages of low relative density, low price, good processing performance and good comprehensive performance, and is widely used in automotive decorative parts, bumpers, lamp accessories, etc. However, existing polypropylene composite materials have the defects of low tensile strength and poor creep resistance, which greatly limits their application in plastic products with high working environment temperature (such as plastic parts of engines).

[0003] Therefore, there is an urgent need to develop a polypropylene composite material with good creep resistance to meet the performance requirements of plastic products with high working environment temperatures for polypropylene composite materials. Summary of the invention

[0004] Based on the defects of the prior art, the object of the present invention is to provide a light-transmitting creep-resistant polypropylene composite material and a preparation method and application thereof.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a light-transmitting creep-resistant polypropylene composite material, comprising the following components in parts by weight:

[0007] 24-51 parts of homopolypropylene resin, 10-25 parts of random copolymer polypropylene resin, 22-35 parts of glass fiber, 2-5 parts of compatibilizer, 0.3-1 part of transparent nucleating agent, and 5-15 parts of linear low-density polyethylene. The melt mass flow rate of the homopolypropylene resin at 230°C and 2.16Kg load is not more than 5g / 10min, the melt mass flow rate of the random copolymer polypropylene resin at 230°C and 2.16Kg load is not more than 3g / 10min, and the melt flow rate of the linear low-density polyethylene at 190°C and 2.16kg load is not more than 4g / 10min.

[0008] The present invention adopts homopolymer polypropylene resin, random copolymer polypropylene resin, linear low-density polyethylene glass fiber, transparent nucleating agent and the like for compounding, which can improve the light transmittance and tensile strength of the composite material while effectively improving the creep resistance of the composite material at high temperature (≥100°C), and can meet the requirements of plastic products with high working environment temperature on the performance of polypropylene composite materials.

[0009] The inventors have found that by introducing linear low-density polyethylene with a melt flow rate of no more than 4g / 10min and utilizing the large number of short branches it contains, the branching degree of the polyethylene molecular chain is increased, and the entanglement degree of the molecular chains of the composite material is aggravated, which is beneficial to improving the creep resistance of the composite material.

[0010] Preferably, in the light-transmitting creep-resistant polypropylene composite material, the sum of the mass percentages of the homopolymer polypropylene resin and the random copolymer polypropylene resin is not less than 50%.

[0011] Preferably, the melt mass flow rate of the homopolypropylene resin at 230° C. and 2.16Kg load is 2 to 5g / 10min, and the melt flow ratio of the homopolypropylene resin is 7 to 12. For example, the melt mass flow rate of the homopolypropylene resin at 230° C. and 2.16Kg load can be 2g / 10min, 2.2g / 10min, 2.5g / 10min, 3g / 10min, 3.5g / 10min, 4g / 10min, 4.5g / 10min, 5g / 10min, or a range consisting of any two groups of values ​​therein; the melt flow ratio of the homopolypropylene resin can be 7, 8, 9, 10, 11, 12, or a range consisting of any two groups of values ​​therein. The inventors have found through research that when the melt mass flow rate and melt flow ratio of the homopolymer polypropylene resin meet the above conditions, the homopolymer polypropylene resin can not only effectively form molecular chain entanglements, but also ensure the processing performance of the material, thereby avoiding the shortening of the retained length of the glass fiber during the processing due to affecting the processing performance of the material, thereby avoiding adverse effects on the creep resistance of the composite material.

[0012] Further preferably, the homopolymer polypropylene resin has a melt mass flow rate of 3.5 to 4 g / 10 min at 230° C. and a load of 2.16 kg.

[0013] Preferably, the melt mass flow rate of the random copolymer polypropylene resin at 230° C. and 2.16 kg load is 0.9 to 3 g / 10 min. For example, the melt mass flow rate of the random copolymer polypropylene resin at 230° C. and 2.16 kg load can be 0.9 g / 10 min, 1 g / 10 min, 1.5 g / 10 min, 1.8 g / 10 min, 2 g / 10 min, 2.1 g / 10 min, 2.2 g / 10 min, 2.5 g / 10 min, 2.8 g / 10 min, 3 g / 10 min, or a range consisting of any two groups of values.

[0014] Further preferably, the random copolymer polypropylene resin has a melt mass flow rate of 1.8 to 2 g / 10 min at 230° C. and a load of 2.16 kg.

[0015] Preferably, the melt flow ratio of the random copolymer polypropylene resin is 7-12.

[0016] The melt flow ratio of the random copolymer polypropylene resin is the ratio between the melt mass flow rate of the random copolymer polypropylene resin and its melt volume flow rate, wherein the test method for the melt mass flow rate of the random copolymer polypropylene resin is the method specified in the standard ISO1133-2011, the test temperature is 230°C, and the load is 2.16Kg; the test method for the melt volume flow rate of the random copolymer polypropylene resin is the method specified in the standard ISO1133-2011, the test temperature is 230°C, and the load is 2.16Kg.

[0017] Preferably, the melt flow rate of the linear low-density polyethylene at 190°C and a load of 2.16 kg is 1 to 3 g / 10 min. For example, the melt mass flow rate of the linear low-density polyethylene at 190°C and a load of 2.16 kg may be 1 g / 10 min, 1.5 g / 10 min, 2 g / 10 min, 2.5 g / 10 min, 3 g / 10 min, or a range consisting of any two groups of values.

[0018] Preferably, the average diameter of the glass fiber is 6 to 12 μm, more preferably 8 to 10 μm.

[0019] Preferably, the average length of the glass fibers is 3 to 5 mm.

[0020] The present invention adopts a microscope method to test the average diameter of the glass fiber, and adopts a ruler method to test the average length of the glass fiber.

[0021] The inventors have found through research that glass fibers with an average diameter of 8 to 10 μm are not only easy to process, cause little damage to processing equipment, and have low cost, but can also be better dispersed in polypropylene melts, significantly enhancing the mechanical properties of composite materials while improving the creep resistance of the material.

[0022] Preferably, the nucleating agent is a β-nucleating agent.

[0023] In the present invention, the β-nucleating agent may be at least one of a sorbitol nucleating agent, a condensed ring compound nucleating agent and an aromatic amide nucleating agent.

[0024] Preferably, the compatibilizer includes at least one of maleic anhydride grafted polypropylene, glycidyl methacrylate grafted polypropylene, and propylene-acrylate-glycidyl methacrylate terpolymer.

[0025] Preferably, the light-transmitting creep-resistant polypropylene composite material further comprises an auxiliary agent, and the auxiliary agent comprises at least one of an antioxidant and a light stabilizer.

[0026] Based on the needs of practical applications, those skilled in the art can appropriately introduce some common auxiliary components without adversely affecting the performance of polypropylene composite materials, for example, antioxidants for improving the aging resistance of composite materials, light stabilizers for improving the light stability of composite materials, and weathering agents for improving the weather resistance of composite materials. In the present invention, the antioxidant can be at least one of phosphite antioxidants and hindered phenol antioxidants; the light stabilizer can be at least one of benzotriazole light stabilizers and hindered amine light stabilizers.

[0027] Further preferably, in the light-transmitting creep-resistant polypropylene composite material, the weight proportions of the components of the auxiliary agents are: 0.1 to 1 part of antioxidant, and 0.1 to 1 part of weathering agent.

[0028] More preferably, in the light-transmitting creep-resistant polypropylene composite material, the weight proportions of the auxiliary agent components are: 0.6 to 0.8 parts of antioxidant, and 0.4 to 0.6 parts of weathering agent.

[0029] Preferably, the light-transmitting creep-resistant polypropylene composite material comprises the following components in parts by weight: 30-38 parts of homopolymer polypropylene resin, 15-20 parts of random copolymer polypropylene resin, 25-30 parts of glass fiber, 3-4 parts of compatibilizer, 0.5-0.8 parts of transparent nucleating agent, and 8-12 parts of linear low-density polyethylene.

[0030] In a second aspect, the present invention provides a method for preparing the light-transmitting creep-resistant polypropylene composite material as described in the first aspect, comprising the following steps:

[0031] The components are mixed and then melt-blended, extruded and granulated to obtain the light-transmitting creep-resistant polypropylene composite material.

[0032] In a third aspect, the present invention provides a use of the light-transmitting, creep-resistant polypropylene composite material as described in the first aspect in the preparation of plastic products.

[0033] The plastic products may be plastic parts for automobile decoration, bumpers, and plastic accessories for headlights; they may also be plastic products with high working temperatures, such as plastic accessories for engines.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention is compounded by homopolymer polypropylene resin, copolymer polypropylene resin, linear low-density polyethylene, glass fiber, transparent nucleating agent and other components, which can effectively improve the tensile strength and light transmittance of the composite material, and can also effectively improve the creep resistance of the composite material, and can meet the requirements of plastic products with high working environment temperature on the performance of polypropylene composite materials. DETAILED DESCRIPTION

[0036] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments and comparative examples, the purpose of which is to understand the content of the present invention in detail, rather than to limit the present invention. All other embodiments obtained by those of ordinary skill in the art without making creative work premise belong to the protection scope of the present invention. The experimental reagents and instruments involved in the implementation of the present invention, unless otherwise specified, are all commonly used common reagents and instruments.

[0037] In the present invention, the test method for the melt mass flow rate of the homopolypropylene resin is the method specified in the standard ISO1133-2011, the test temperature is 230° C., and the load is 2.16 Kg.

[0038] In the present invention, the melt flow ratio of the homopolypropylene resin is the ratio between the melt mass flow rate of the homopolypropylene resin and its melt volume flow rate, wherein the test method for the melt mass flow rate of the homopolypropylene resin is the method specified in the standard ISO1133-2011, the test temperature is 230°C, and the load is 5Kg; the test method for the melt volume flow rate of the homopolypropylene resin is the method specified in the standard ISO1133-2011, the test temperature is 230°C, and the load is 16Kg.

[0039] In the present invention, the test method for the melt mass flow rate of the copolymerized polypropylene resin is the method specified in the standard ISO1133-2011, the test temperature is 230° C., and the load is 2.16 Kg.

[0040] In the present invention, the test method for the melt flow rate of the linear low-density polyethylene is the method specified in the standard ISO1133-2011, the test temperature is 190° C., and the load is 2.16 Kg.

[0041] In the present invention, the test method for the melt flow rate of the high-density polyethylene is the method specified in the standard ISO1133-2011, the test temperature is 190° C., and the load is 2.16 Kg.

[0042] The source information and performance parameters of the components described in each embodiment and comparative example are shown in Table 1 below.

[0043] Table 1

[0044]

[0045]

[0046] Unless otherwise specified, the components and raw materials used in the embodiments and comparative examples of the present invention are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0047] Examples 1 to 15

[0048] The embodiment of the light-transmitting creep-resistant polypropylene composite material of the present invention, the components and weight proportions of the light-transmitting creep-resistant polypropylene composite material are shown in Table 2.

[0049] The preparation method of the light-transmitting creep-resistant polypropylene composite material comprises the following steps:

[0050] After mixing the components, the components are melt-blended, extruded and granulated at 220-240° C. using a twin-screw extruder, and dried to obtain the light-transmitting creep-resistant polypropylene composite material. The screw speed of the twin-screw extruder is 400 rpm, and the screw aspect ratio is 40:1.

[0051] Table 2 (Unit: parts by weight)

[0052]

[0053]

[0054] Comparative Examples 1 to 6

[0055] The difference between the comparative examples and the embodiments is only in the component types and proportions, as shown in Table 3.

[0056] Table 3 (Unit: weight parts)

[0057]

[0058]

[0059] In order to verify the performance of the composite material of the present invention, the composite materials prepared in each embodiment and comparative example were used as samples to perform the following performance tests:

[0060] (1) Tensile strength: injection molded ISO 527 1A specimens, tested according to ISO 527-2012 method, test temperature is 23 °C, tensile rate is 50 mm / min;

[0061] (2) Creep holding time: Injection molded ISO 527 1A specimens were tested according to the GB / T11546.1 2008 method at a test temperature of 120°C and a test load of 14 MPa. The creep rupture time of the specimens at this temperature and load was recorded.

[0062] (3) Light transmittance: The samples were injection molded into specimens with a size of 100 mm × 100 mm × 3 mm and tested in accordance with GB / T 2410-2008.

[0063] The test results are shown in Tables 4 and 5.

[0064] Table 4

[0065]

[0066] Table 5

[0067]

[0068] It can be seen from Examples 1-15 that the present invention can effectively improve the tensile properties and light transmittance of the composite material by compounding components such as homopolymer polypropylene resin, copolymer polypropylene resin, linear low-density polyethylene, glass fiber, and transparent nucleating agent, and can also effectively improve the creep resistance of the composite material. The tensile strength of the composite material is not less than 102 MPa, the light transmittance is not less than 61%, and the high-temperature creep rupture time is not less than 6 hours. This shows that the present invention can meet the requirements of the performance of polypropylene composite materials for plastic products with high working environment temperatures.

[0069] It can be seen from Example 1, Examples 6 to 8 and Comparative Example 1 that when the melt mass flow rate of the homopolymer polypropylene resin is ≤5 g / 10 min, the homopolymer polypropylene resin can not only form molecular chain entanglements more effectively, but also better ensure the processing performance of the material, thereby significantly improving the creep resistance of the polypropylene composite material.

[0070] It can be seen from Example 1, Examples 9 to 11 and Comparative Examples 2 to 3 that by controlling the melt mass flow rate of the random copolymer polypropylene resin to be no more than 3 g / 10 min, the creep resistance and tensile strength of the polypropylene composite material can be significantly improved while ensuring light transmittance.

[0071] It can be seen from Example 1, Example 15, Comparative Example 4 and Comparative Example 6 that when the melt flow rate of the linear low-density polyethylene is not more than 4 g / 10 min, the addition of the linear low-density polyethylene can not only improve the light transmittance of the polypropylene composite material to a certain extent, but also effectively increase the branching degree of the polyethylene molecular chain and increase the entanglement degree of the polyethylene molecular chain, thereby significantly improving the creep resistance of the composite material.

[0072] Compared with Example 1, the amount of linear low-density polyethylene added in Comparative Example 5 is too small, and the short branches introduced by itself are reduced accordingly, which cannot effectively increase the branching degree of the polyethylene molecular chain, thereby deteriorating the creep resistance of the composite material.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A light-transmitting creep-resistant polypropylene composite material, characterized in that: The composition comprises the following components in parts by weight: 24-51 parts of homopolypropylene resin, 10-25 parts of random copolymer polypropylene resin, 22-35 parts of glass fiber, 2-5 parts of compatibilizer, 0.3-1 part of transparent nucleating agent, and 5-15 parts of linear low-density polyethylene. The melt mass flow rate of the homopolypropylene resin at 230°C and 2.16Kg load is not more than 5g / 10min, the melt mass flow rate of the random copolymer polypropylene resin at 230°C and 2.16Kg load is not more than 3g / 10min, and the melt flow rate of the linear low-density polyethylene at 190°C and 2.16kg load is not more than 4g / 10min.

2. The light-transmitting creep-resistant polypropylene composite material according to claim 1, characterized in that: The homopolymer polypropylene resin has a melt mass flow rate of 2 to 5 g / 10 min at 230° C. and a load of 2.16 kg, preferably 3.5 to 4 g / 10 min.

3. The light-transmitting creep-resistant polypropylene composite material according to claim 1, characterized in that: The melt flow ratio of the homopolymer polypropylene resin is 7-12.

4. The light-transmitting creep-resistant polypropylene composite material according to claim 1, characterized in that: The random copolymer polypropylene resin has a melt mass flow rate of 0.9 to 3 g / 10 min at 230° C. and a load of 2.16 kg, preferably 1.8 to 2 g / 10 min.

5. The light-transmitting creep-resistant polypropylene composite material according to claim 1, characterized in that: The linear low-density polyethylene has a melt flow rate of 1 to 3 g / 10 min at 190° C. and a load of 2.16 kg.

6. The light-transmitting creep-resistant polypropylene composite material according to claim 1, characterized in that: At least one of the following (I) to (III): (I) the average diameter of the glass fiber is 6 to 12 μm, preferably 8 to 10 μm; (II) the nucleating agent is a β-nucleating agent; (III) The compatibilizer includes at least one of maleic anhydride grafted polypropylene, glycidyl methacrylate grafted polypropylene, and propylene-acrylate-glycidyl methacrylate terpolymer.

7. The light-transmitting creep-resistant polypropylene composite material according to claim 1, characterized in that: The invention also includes auxiliary agents, which include at least one of an antioxidant and a light stabilizer.

8. The light-transmitting creep-resistant polypropylene composite material according to claim 1, characterized in that: The invention comprises the following components in parts by weight: 30-38 parts of homopolymer polypropylene resin, 15-20 parts of random copolymer polypropylene resin, 25-30 parts of glass fiber, 3-4 parts of compatibilizer, 0.5-0.8 parts of transparent nucleating agent and 8-12 parts of linear low-density polyethylene.

9. A method for preparing the light-transmitting creep-resistant polypropylene composite material according to any one of claims 1 to 8, characterized in that: The following steps are involved: The components are mixed and then melt-blended, extruded and granulated to obtain the light-transmitting creep-resistant polypropylene composite material.

10. Use of the light-transmitting creep-resistant polypropylene composite material according to any one of claims 1 to 8 in the preparation of plastic products.

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