Glass fiber reinforced polypropylene composite material as well as preparation method and application thereof

Abstract

The invention discloses a glass fiber reinforced polypropylene composite material as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. According to the invention, two specific modifiers are introduced, so that the temperature required by dipping processing can be reduced, the polypropylene composite material has good appearance, and the mechanical property and flame retardant property of the polypropylene composite material can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a glass fiber reinforced polypropylene composite material, a preparation method thereof, and an application thereof. Background Art

[0002] The glass fiber reinforced polypropylene composite material not only has the advantages of light weight, low cost, and excellent mechanical properties, but also has high strength, high modulus, excellent impact toughness, and recyclability, making it more and more widely used in the fields of automobiles, buildings, engineering equipment, etc. However, polypropylene is extremely easy to burn, with an oxygen index of only 17-18%, and a fast burning rate, which limits its application in fields with higher flame retardant grade requirements. Traditional glass fiber reinforced flame retardant polypropylene composite materials are generally obtained by multi-layer compounding of glass fiber reinforced flame retardant polypropylene unidirectional tapes. Due to the addition of flame retardants in the flame retardant unidirectional tapes, the amount of polypropylene substrate is relatively reduced, resulting in poor wetting effect of glass fibers, leading to defects in the appearance of the tapes, such as the generation of white filaments, cracking, etc., and also reducing the interlaminar shear strength of the later composite materials. At the same time, the compatibility between the flame retardant and polypropylene is poor, so that the impregnation temperature needs to be controlled above 270°C. However, processing at this impregnation temperature is likely to cause yellow spots in the composite material and also affect the flame retardant performance of the composite material.

[0003] Therefore, it is very necessary to prepare a glass fiber reinforced polypropylene composite material with good appearance suitable for low-temperature impregnation (not higher than 260°C). Summary of the Invention

[0004] Based on the defects existing in the prior art, the purpose of the present invention is to provide a glass fiber reinforced polypropylene composite material, a preparation method thereof, and an application thereof. By introducing two specific modifiers, the present invention can not only reduce the temperature required for impregnation processing, make the polypropylene composite material have good appearance, but also effectively improve the mechanical properties and flame retardant properties of the polypropylene composite material.

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

[0006] In the first aspect, a glass fiber reinforced polypropylene composite material provided by the present invention comprises the following components in parts by weight:

[0007] 10-30 parts of polypropylene, 5-15 parts of a first modifier, 0.4-1 part of a second modifier, 20-35 parts of a flame retardant, 3-8 parts of a compatibilizer, and 35-60 parts of glass fiber;

[0008] The polypropylene is at least one of copolymerized polypropylene and homopolymerized polypropylene, wherein the mass percentage of copolymerized polypropylene in the polypropylene is not less than 20%;

[0009] The first modifier is ethylene-vinyl acetate copolymer, and the melt index of the ethylene-vinyl acetate copolymer at 190 °C and a load of 2.16 Kg is not less than 3 g / 10 min.

[0010] The second modifier includes at least one of ethyl ethoxylated amide stearate, high-carbon chain ethoxylated amide wax, and glycerol monostearate.

[0011] The inventors have found through research that by introducing the first modifier and the second modifier in the present invention, the halogen-free flame retardant is more uniformly dispersed in the melt, giving the polypropylene composite material a good appearance, and at the same time effectively improving the mechanical properties and flame retardant properties of the polypropylene composite material.

[0012] In the present invention, the weight percentage of the polypropylene in the glass fiber reinforced polypropylene composite material is preferably not less than 13%.

[0013] In the present invention, the melting point of the high-carbon chain ethoxylated amide wax is 65-75 °C, and the high-carbon chain in the high-carbon chain ethoxylated amide wax refers to a branched or straight-chain alkane chain with not less than 20 carbon atoms. The number of carbon atoms in the high-carbon chain is preferably 20-30.

[0014] As a preferred embodiment of the present invention, the melt index of the ethylene-vinyl acetate copolymer at 190 °C and a load of 2.16 Kg according to ISO 1133-1:2011 is 3-70 g / 10 min. For example, the melt index of the ethylene-vinyl acetate copolymer at 190 °C and a load of 2.16 Kg can be 3 g / 10 min, 7 g / 10 min, 10 g / 10 min, 15 g / 10 min, 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, 40 g / 10 min, 50 g / 10 min, 56 g / 10 min, 60 g / 10 min, 65 g / 10 min, 70 g / 10 min or a range composed of any two sets of these values.

[0015] More preferably, the melt index of the ethylene-vinyl acetate copolymer at 190 °C and a load of 2.16 Kg is 56-65 g / 10 min. When the melt index of the ethylene-vinyl acetate copolymer used in the present invention is in the range of 56-65 g / 10 min, the flame retardant is more uniformly dispersed in the system, the impregnation effect of the glass fiber is better, and the mechanical properties of the polypropylene composite material are more excellent.

[0016] As a preferred embodiment of the present invention, the copolymerized polypropylene has a melt index of 25 - 110 g / 10 min at 230°C and a load of 2.16 Kg according to ISO 1133-1:2011. For example, the melt index of the copolymerized polypropylene at 230°C and a load of 2.16 Kg according to ISO 1133-1:2011 can be 25 g / 10 min, 30 g / 10 min, 40 g / 10 min, 50 g / 10 min, 60 g / 10 min, 70 g / 10 min, 80 g / 10 min, 90 g / 10 min, 95 g / 10 min, 100 g / 10 min, 105 g / 10 min, 110 g / 10 min or a range composed of any two sets of these values.

[0017] More preferably, the melt index of the copolymerized polypropylene at 230°C and a load of 2.16 Kg according to ISO 1133-1:2011 is 95 - 105 g / 10 min.

[0018] As a preferred embodiment of the present invention, the homopolymerized polypropylene has a melt index of 20 - 70 g / 10 min at 230°C and a load of 2.16 Kg according to ISO 1133-1:2011. For example, the melt index of the homopolymerized polypropylene at 230°C and a load of 2.16 Kg according to ISO 1133-1:2011 can be 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, 40 g / 10 min, 50 g / 10 min, 55 g / 10 min, 60 g / 10 min, 65 g / 10 min, 70 g / 10 min or a range composed of any two sets of these values.

[0019] More preferably, the melt index of the homopolymerized polypropylene at 230°C and a load of 2.16 Kg according to ISO 1133-1:2011 is 55 - 65 g / 10 min.

[0020] In the present invention, the mass percentage of the copolymerized polypropylene in the polypropylene can be 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% or a range composed of any two sets of these values.

[0021] Preferably, the polypropylene comprises copolymerized polypropylene and homopolymerized polypropylene, and the mass percentage of the copolymerized polypropylene in the polypropylene is 20 - 60%.

[0022] The inventors have found through research that the compounding of copolymerized polypropylene and homopolymerized polypropylene can improve the wetting effect of glass fibers while ensuring the tensile strength of the composite material and avoiding obvious appearance defects in the material.

[0023] As a preferred embodiment of the present invention, the flame retardant is a halogen-free flame retardant; the halogen-free flame retardant includes at least one of piperazine pyrophosphate and ammonium polyphosphate.

[0024] As a preferred embodiment of the present invention, the compatibilizer includes maleic anhydride grafted polypropylene.

[0025] As a preferred embodiment of the present invention, the glass fiber reinforced polypropylene composite material comprises the following components in parts by weight:

[0026] 20 - 25 parts of polypropylene, 8 - 12 parts of the first modifier, 0.5 - 0.8 parts of the second modifier, 24 - 30 parts of the flame retardant, 4 - 6 parts of the compatibilizer, and 50 - 55 parts of glass fiber. When the parts by weight of each component meet this condition, it can not only be applicable to the low-temperature impregnation process, but also endow the polypropylene composite material with good appearance, excellent flame retardant performance, and better mechanical properties.

[0027] As a preferred embodiment of the present invention, the glass fiber reinforced polypropylene composite material further comprises the following components in parts by weight: 0.5 - 2 parts of an auxiliary agent, and the auxiliary agent includes at least one of an antioxidant and a lubricant.

[0028] Based on the needs of the actual product, those skilled in the art can appropriately introduce some common components introduced into the glass fiber reinforced polypropylene composite material without affecting the product performance, such as an antioxidant to improve the aging resistance of the product, a lubricant to improve the processing performance of the product, and so on.

[0029] In a second aspect, the present invention provides a method for preparing the glass fiber reinforced polypropylene composite material as described in the first aspect, comprising the following steps:

[0030] S1. Mix and melt the components except glass fiber to obtain a molten polypropylene melt;

[0031] S2. Impregnate the glass fiber with the polypropylene melt obtained in step S1, and after cooling, shaping, slitting, and winding, obtain the glass fiber reinforced polypropylene composite material.

[0032] As a preferred embodiment of the present invention, the temperature of mixing and melting in step S1 is not higher than 260 °C, and more preferably 230 - 260 °C.

[0033] In a third aspect, the present invention provides an application of the glass fiber reinforced polypropylene composite material as described in the first aspect in the preparation of a sealing cover for a new energy vehicle.

[0034] The beneficial effects of the present invention are as follows. By introducing two specific modifiers, the present invention can not only reduce the temperature required for impregnation processing, enabling the polypropylene composite material to have a good appearance, but also effectively improve the mechanical properties and flame retardancy of the polypropylene composite material. Detailed implementation manners

[0035] To better illustrate the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with specific examples and comparative examples. The purpose is to understand the content of the present invention in detail, rather than limiting the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. The experimental reagents and instruments involved in the implementation of the present invention are all common ordinary reagents and instruments unless otherwise specified.

[0036] The source information and performance parameters of the components in each example and comparative example are shown in Table 1 below.

[0037] Table 1

[0038]

[0039]

[0040] Unless otherwise specified, the component raw materials used in each example and comparative example of the present invention are all commercially available raw materials, and the component raw materials used in each parallel experiment are all of the same kind.

[0041] Examples 1-14

[0042] Examples of the fiber-reinforced flame-retardant polypropylene composite material of the present invention. The composition of the fiber-reinforced flame-retardant polypropylene composite material is shown in Table 2. The preparation method of the fiber-reinforced flame-retardant polypropylene composite material is as follows:

[0043] S1. Add the components except glass fiber into a twin-screw extruder for mixing and melting to obtain a molten polypropylene melt;

[0044] In step S1, the temperature of each section of the twin-screw extruder is 260 °C, and the main machine speed is 300 r / min;

[0045] S2. Feed the polypropylene melt obtained in step S1 into an impregnation mold. After preheating and spreading the glass fiber through a fiber spreading device, it enters the impregnation mold. Under the action of heat and tension, the molten polypropylene melt impregnates and coats the glass fiber in the impregnation mold, and then through cooling, shaping, slitting and winding, the fiber-reinforced flame-retardant polypropylene composite material is obtained;

[0046] In step S2, the temperature in the impregnation mold is 230-270 °C.

[0047] Comparative Examples 1-6

[0048] The differences between each comparative example and the examples lie only in the types and ratios of components, as shown in Table 3.

[0049] Table 2 (unit: parts by weight)

[0050]

[0051] Table 3 (unit: parts by weight)

[0052]

[0053]

[0054] To verify the performance of the fiber-reinforced flame-retardant polypropylene composite material of the present invention, the materials prepared in each example and comparative example were subjected to the following performance tests, and the specific steps are as follows:

[0055] (1) White fiber grade test: Cut the product into strips with a size of 300 mm * 300 mm * 0.25 mm, and judge by visual inspection. White fibers refer to the appearance defects that exist on the unidirectional tape of the material and are not fully impregnated with resin and are shown. They are divided into four grades. Among them, Grade 1: Basically no white fibers; Grade 2: Slight white fibers; Grade 3: A large number of white fibers; Grade 4: Severe white fibers.

[0056] (2) Cracking grade test: Cut the product into strips with a size of 300 mm * 300 mm * 0.25 mm. Cracking refers to the phenomenon of cracks existing on the unidirectional tape of the material, and is characterized by the total length of the cracks on the same unidirectional tape. It is divided into 4 grades. Among them, Grade 1: Total length ≤ 10 mm; Grade 2: 10 mm < total length ≤ 30 mm; Grade 3: 30 mm < total length ≤ 50 mm; Grade 4: Total length > 50 mm.

[0057] (3) Interlaminar shear strength: After laying the strips, hot press them into a 3-mm-thick plate at 210 °C, and then cut it into test specimens with a size of 30 mm * 13 mm * 3 mm, and test them with reference to ISO 14130:1997.

[0058] (4) Tensile strength: After laying the strips, hot press them into a 3-mm-thick plate at 210 °C, and then cut it into test specimens with a size of 180 mm * 10 mm * 3 mm, and test them with reference to GB / T 1447-2005.

[0059] (5) Flame retardancy: After laying the strips, hot press them into a 1.5-mm-thick plate at 210 °C, and then cut it into test specimens with a size of 125 mm * 12.7 mm * 1.5 mm, and test them with reference to UL94.

[0060] The test results are shown in Table 4-5.

[0061] Table 4

[0062]

[0063]

[0064] Table 5

[0065]

[0066] It can be seen from Examples 1-14 that the glass fiber reinforced polypropylene composite provided by the present invention has good appearance, excellent mechanical properties and flame retardant properties. The white silk grade is not higher than 2, the cracking grade is higher than 2, the interlaminar shear strength is not lower than 19.2 MPa, the tensile strength is not lower than 205 MPa, and the flame retardant grade reaches V-0, which is suitable for preparing the sealing cover of new energy vehicles.

[0067] It can be seen from Example 1, Examples 9-10 and Comparative Example 1 that compared with erucamide, the present invention introduces ethyl stearate ethoxylate, high-carbon chain ethoxylated amide wax or glycerol monostearate as the second modifier, which can improve the dispersibility of the flame retardant in the system, thereby enhancing the flame retardancy of the composite material and avoiding the agglomeration of the flame retardant, which increases the white silk and cracking defects; the erucamide used in Comparative Example 1 is prone to precipitation and cannot play a good role in improving the dispersibility of the flame retardant in the system, resulting in a decrease in the flame retardant performance of the composite material and a significant increase in the white silk and cracking defects.

[0068] Compared with Example 1 and Examples 11-14, in Comparative Example 2, the ratio of copolymerized polypropylene to homopolymerized polypropylene is inappropriate, and the impregnation effect of polypropylene on glass fiber is poor, resulting in a significant deterioration of the mechanical properties of the composite material and an increase in white silk and cracking defects.

[0069] It can be seen from Examples 1-4 and Comparative Examples 4-6 that the present invention compounded 20-25 parts by weight of polypropylene, 8-12 parts by weight of the first modifier, 0.5-0.8 parts by weight of the second modifier, 20-30 parts by weight of the flame retardant, 4-6 parts by weight of the compatibilizer and 50-55 parts by weight of glass fiber, and the comprehensive performance of the composite material is better; the addition amount of the first modifier in Comparative Example 3 is too small, resulting in insufficient impregnation of glass fiber and thus generating a large amount of white silk and an increase in crack length; the addition amount of the first modifier in Comparative Example 4 is too large, resulting in uneven dispersion of the first modifier in the system and thus reducing the mechanical properties of the composite material; the addition amount of the second modifier in Comparative Example 5 is too small, and the improvement effect on the dispersibility of the flame retardant is not obvious, resulting in agglomeration of the flame retardant and affecting the flame retardant performance; the addition amount of the second modifier in Comparative Example 6 is too large, and the second modifier is prone to precipitate on the surface during the impregnation process, resulting in uneven dispersion of the flame retardant and affecting the flame retardant performance.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A glass fiber reinforced polypropylene composite material, characterized in that, Comprising the following components in parts by weight: 10 - 30 parts of polypropylene, 5 - 15 parts of a first modifier, 0.4 - 1 part of a second modifier, 20 - 35 parts of a flame retardant, 3 - 8 parts of a compatibilizer, 35 - 60 parts of glass fiber; The polypropylene is at least one of copolymerized polypropylene and homopolymerized polypropylene, wherein the mass percentage of copolymerized polypropylene in the polypropylene is not less than 20%; The first modifier is ethylene - vinyl acetate copolymer, and the melt index of the ethylene - vinyl acetate copolymer under a load of 2.16 Kg at 190 °C is not less than 3 g / 10 min; The second modifier includes at least one of ethyl ethoxylated stearamide, high - carbon chain ethoxylated amide wax, and glycerol monostearate.

2. The glass fiber reinforced polypropylene composite material according to claim 1, wherein, The melt index of the ethylene - vinyl acetate copolymer under a load of 2.16 Kg at 230 °C is 3 - 70 g / 10 min, preferably 55 - 65 g / 10 min.

3. The glass fiber reinforced polypropylene composite material according to claim 1, characterized in that The melt index of the copolymerized polypropylene under a load of 2.16 Kg at 230 °C is 25 - 110 g / 10 min.

4. The glass fiber reinforced polypropylene composite material according to claim 1, wherein, The melt index of the homopolymerized polypropylene under a load of 2.16 Kg at 230 °C is 20 - 70 g / 10 min.

5. The glass fiber reinforced polypropylene composite material according to claim 1, characterized in that, The flame retardant is a halogen - free flame retardant.

6. The glass fiber reinforced polypropylene composite material according to claim 1, characterized in that, The compatibilizer includes maleic anhydride grafted polypropylene.

7. The glass fiber reinforced polypropylene composite material according to claim 1, wherein It further comprises the following components in parts by weight: 0.5 - 2 parts of an auxiliary agent, and the auxiliary agent includes at least one of an antioxidant and a lubricant.

8. A method for preparing a glass fiber reinforced polypropylene composite material according to any one of claims 1 to 7, characterized in that, Comprising the following steps: S1. Mix and melt the components except glass fiber to obtain a molten polypropylene melt; S2. Impregnate the glass fiber with the polypropylene melt prepared in step S1, and after cooling, shaping, slitting, and winding, obtain the glass fiber reinforced polypropylene composite material.

9. Use of the glass fiber reinforced polypropylene composite material according to any one of claims 1 - 7 in the preparation of a sealing cover for a new energy vehicle.

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