Modified glass fiber and preparation method and application thereof

Abstract

The invention discloses a modified glass fiber and a preparation method and application thereof. The surface of the glass fiber is coated with a modifier, and the modifier is an acrylate-acrylic acid amide polymer; and the content of the modifier accounts for 2-8 wt% of the modified glass fiber. According to the invention, the modifier is adopted to modify the glass fiber, and the modifier is of a chain-shaped molecular structure, is distributed on the surface of the glass fiber, is beneficial to compatibility of the glass fiber and polypropylene resin, and can form a relatively strong riveting effect with the surface of the glass fiber; when the glass fiber reinforced polypropylene is added into polypropylene resin, the warping problem and the toughness reduction problem of the glass fiber reinforced polypropylene can be effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of general plastics, and more specifically to a modified glass fiber and a preparation method and application thereof. Background Art

[0002] With the rapid development of new energy vehicles, the entire automotive components tend to be lightweight to reduce the weight of the vehicle and achieve the need for a longer driving range. In addition, the drive form of new energy vehicles is different. Long-term use of high-density materials such as nylon has excess performance, which can be replaced by olefins. For example, glass fiber reinforced polypropylene materials can be used to replace nylon reinforced materials, which not only meets the demand for lightweight, but also meets the comprehensive performance requirements.

[0003] However, glass fiber reinforced polypropylene materials have a natural defect of warping. For the precision requirements of automotive functional parts, such as sunroof brackets, front frame, cooling fan, low-temperature water chamber, etc., it is necessary to modify the glass fiber reinforced polypropylene materials to reduce their warping. In the prior art, low-warping glass fiber reinforced polypropylene is prepared by composite filling with sericite filler and glass fiber, but it is found that the problem of reduced toughness exists during the application process. Therefore, in view of the higher requirements of the automotive industry, the field urgently needs to develop a low-warping and high-toughness polypropylene composition. Summary of the invention

[0004] The purpose of the present invention is to provide a modified glass fiber in order to overcome the defects or shortcomings of the polypropylene material in the prior art.

[0005] Another object of the present invention is to provide a method for preparing the modified glass fiber.

[0006] Another object of the present invention is to provide a low-warpage polypropylene composition.

[0007] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0008] A modified glass fiber, the surface of which is coated with a modifier, which is an acrylate-acrylic amide polymer; the modifier accounts for 2-8wt% of the modified glass fiber.

[0009] The present invention provides a modified glass fiber. The inventors have found that the modified glass fiber can be used to reinforce a polypropylene composition, which can effectively improve the warping problem and the problem of reduced toughness. It is speculated that this may be because the modifier has a chain molecular structure and is distributed on the surface of the glass fiber, which helps it to be compatible with the polypropylene resin; in addition, the modifier has strong adhesion and forms a strong riveting effect with the surface of the glass fiber, thereby improving the mechanical properties of the glass fiber reinforced polypropylene composition; the modifier can effectively control the orientation of the glass fiber and improve the warping problem caused by the glass fiber.

[0010] In the present invention, the content of the modifier accounts for 2 to 8wt% of the modified glass fiber, for example, but not limited to 2wt%, 2.2wt%, 2.5wt%, 2.8wt%, 3wt%, 3.2wt%, 3.5wt%, 3.8wt%, 4wt%, 4.2wt%, 4.5wt%, 4.8wt%, 5wt%, 5.2wt%, 5.5wt%, 5.8wt%, 6wt%, 6.2wt%, 6.5wt%, 6.8wt%, 7wt%, 7.2wt%, 7.5wt%, 7.8wt% or 8wt%, etc. can all achieve the present invention.

[0011] Furthermore, the content of the modifier accounts for 4-6wt% of the modified glass fiber.

[0012] Specifically, the method for determining the content of the modifier is as follows:

[0013] 1) The weight of the tested modified glass fiber is recorded as m0;

[0014] 2) Calcinate in a muffle furnace at 900°C for 30 min, and after cooling, test the residual weight, which is recorded as m1;

[0015] 3) Modifier content calculation: 100% - (m0 - m1) * 100% / m0.

[0016] Furthermore, the average length of the modified glass fiber is 3 to 7 mm.

[0017] Furthermore, the average diameter of the modified glass fiber is 3 to 25 μm.

[0018] Furthermore, the average diameter of the modified glass fiber is 10-13 μm.

[0019] Specifically, the average length and the average diameter are tested by a two-dimensional image tester.

[0020] The present invention also provides a method for preparing the modified glass fiber, comprising the following steps:

[0021] The modifier and glass fiber are mixed, stirred for reaction for 18 to 28 hours, and filtered and dried to obtain the product.

[0022] It should be noted that the modifier described in the present invention can be purchased or homemade.

[0023] Specifically, the modifier is prepared by the following preparation method:

[0024] The product is obtained by reacting water, acrylate monomers and acrylamide monomers in the presence of a catalyst.

[0025] Furthermore, the molar ratio of the acrylic acid ester monomer to the acrylamide monomer is 1:(0.5-1.5).

[0026] Specifically, the acrylic acid ester monomer may be one or more of methyl methacrylate, ethylene glycol dimethacrylate, butyl acrylate or 2-methoxyethyl acrylate.

[0027] The acrylamide monomer may be one or more of acrylamide, N-hydroxymethyl acrylamide, N,N-dimethyl acrylamide, and N-acryloyloxy succinimide.

[0028] Specifically, the catalyst is potassium persulfate.

[0029] Furthermore, the preparation method also adds a solvent to serve as a reaction medium.

[0030] Specifically, the solvent may be tetramethylethylenediamine.

[0031] The present invention also provides a low-warpage polypropylene composition, comprising the following components calculated in parts by weight:

[0032] 50-90 parts of polypropylene resin;

[0033] 10-50 parts of the above modified glass fiber;

[0034] 0.5 to 4 parts of additives.

[0035] It should be noted that the content of the polypropylene resin in the low warpage polypropylene composition of the present invention is not less than 45wt.%. For example, but not limited to, not less than 45wt.%, 50wt.%, 55wt.%, 60wt.%, 65wt.%, 70wt.%, 75wt.%, 80wt.% or 85wt.%, etc. can achieve the present invention.

[0036] Furthermore, the low-warpage polypropylene composition comprises the following components calculated in parts by weight:

[0037] 60-80 parts of polypropylene resin;

[0038] 20-40 parts of the above modified glass fiber;

[0039] 1.2 to 2.5 parts of additives.

[0040] Furthermore, the polypropylene resin is homopolypropylene and / or copolymer polypropylene.

[0041] Furthermore, the polypropylene resin has a melt flow rate of 3 to 100 g / 10 min at 230° C. and 2.16 kg.

[0042] In a specific embodiment, the polypropylene resin has a melt flow rate of 20 to 50 g / 10 min at 230° C. and 2.16 kg.

[0043] Furthermore, the melt flow rate of the polypropylene resin is determined according to ISO 1133-1-2022.

[0044] Furthermore, the auxiliary agent includes an antioxidant, a weathering agent and a lubricant.

[0045] In the present invention, commonly used antioxidants can be selected according to the prior art, such as but not limited to one or more of hindered phenol antioxidants, phosphite antioxidants or thioester antioxidants.

[0046] Specifically, the hindered phenol antioxidant is one or more of N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide) (Irganox 1098), pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 1010), 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 259), β-(4-hydroxy-3,5-di-tert-butylphenyl)propionic acid n-octadecyl (Irganox 259 1076) or 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)acrylate]-1,1-dimethyl}-2,4,8,10-tetraoxaspirocycloundecane (ADK AO-80).

[0047] The phosphite antioxidant is one or more of tris(2,4-di-tert-butylphenyl)phosphite (Irganox 168), bis(2,6-di-tert-butyl-4-tolyl) pentaerythritol phosphite (PEP-36) or 627A.

[0048] The thioester antioxidant is one or more of distearyl thiodipropionate, dilauryl thiodipropionate or pentaerythritol dodecapropylthioate.

[0049] In the present invention, commonly used weathering agents may be selected according to the prior art, such as but not limited to ultraviolet absorbers and / or light stabilizers.

[0050] In the present invention, commonly used lubricants can be selected according to the prior art, for example, but not limited to, the lubricant is at least one of amides, stearates, esters or silicones.

[0051] The present invention also protects a method for preparing the low-warpage polypropylene composition, comprising the following steps:

[0052] S1. The polypropylene resin and the additive are mixed uniformly to obtain a premix;

[0053] S2. The premix described in S1 is fed through the main feeding port, and the modified glass fiber is fed through the side feeding port for melt blending and extrusion granulation to obtain a low-warpage polypropylene composition.

[0054] Furthermore, the extrusion granulation in step S2 adopts a twin-screw extruder.

[0055] Furthermore, the temperature of the twin-screw extruder is 80-120°C in zone 1, 180-200°C in zones 2-5, and 200-230°C in other zones.

[0056] Furthermore, the screw length-to-diameter ratio of the twin-screw extruder is (36-48):1.

[0057] The present invention also protects the use of the low-warpage polypropylene composition in the preparation of automotive parts materials, such as automotive cooling fans, skylight frames, and cabin cover parts.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] The invention provides a modified glass fiber, wherein the content of the modified glass fiber surface modifier accounts for 2-8wt% of the modified glass fiber, the modifier has a chain molecular structure, and is distributed on the surface of the glass fiber to help the glass fiber to be compatible with the polypropylene resin, and forms a strong riveting effect with the surface of the glass fiber, and the modifier can effectively control the orientation of the glass fiber; adding the modifier to the polypropylene resin can effectively avoid the warping problem and the problem of reduced toughness of glass fiber reinforced polypropylene. DETAILED DESCRIPTION

[0060] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0061] The raw materials used in each embodiment and comparative example are:

[0062] Polypropylene resin: PP EP548R, melt flow rate of 30 g / 10 min at 230 °C and 2.16 kg, purchased from CNOOC Shell;

[0063] Modifier:

[0064] Modifier 1: Homemade, the preparation method is as follows:

[0065] 1 kg of water, 1 mol of 2-methoxyethyl acrylate and 1 mol of N-hydroxymethyl acrylamide were weighed and added into a reaction kettle, and then nitrogen was introduced to remove the oxygen dissolved therein. The reaction was stirred for 20 minutes, and 8 mL of solvent tetramethylethylenediamine and 5 g of potassium persulfate catalyst were added. The reaction was stirred for 10 minutes to obtain modifier 1.

[0066] Modifier 2: Homemade, preparation method is as follows:

[0067] 1 kg of water, 1 mol of methyl acrylate and 1 mol of N-hydroxyethyl acrylamide were weighed and added into a reaction kettle, and the reaction was evacuated. Then, nitrogen was introduced to remove the oxygen dissolved therein, and the reaction was stirred for 20 minutes. 8 mL of solvent tetramethylethylenediamine and 5 g of potassium persulfate catalyst were added, and the reaction was stirred for 10 minutes to obtain modifier 2.

[0068] Modifier 3: poly(lactic acid-co-glycolic acid) purchased from Newbridge Biotechnology.

[0069] Silane coupling agent: KH-550, purchased from Jinan Rongguang.

[0070] Fiberglass:

[0071] Glass fiber 1: ECS13-04-508A, average length 4 mm, purchased from Jushi Group.

[0072] Glass fiber 2: ECS10-4.5-534AKF, average length 4.5 mm, purchased from Jushi Group.

[0073] Additives:

[0074] Antioxidant: a mixture of antioxidant 1010 (SONOX) and antioxidant 168 (SONOX) in a mass ratio of 1:2;

[0075] Lubricant: calcium stearate; the additives are all commercially available, and the parallel experiments of the examples and comparative examples in the present invention all use the same processing additives.

[0076] Examples 1 to 6 and Comparative Examples 1 to 4

[0077] A modified glass fiber is provided in Examples 1 to 6 and Comparative Examples 1 to 4, which is prepared by the following method according to the formula in Table 1:

[0078] The modifier and glass fiber are mixed, stirred for reaction for 24 hours, filtered, and dried at room temperature to obtain modified glass fiber.

[0079] Table 1 Specific formula of modified glass fiber (unit: weight parts)

[0080]

[0081] Examples 7 to 14 and Comparative Examples 5 to 9

[0082] The polypropylene compositions described in Examples 7 to 14 and Comparative Examples 5 to 9 were prepared according to the formulations in Table 2 by the following preparation method:

[0083] S1. The polypropylene resin and additives are put into a mixer and mixed to obtain a premix;

[0084] S2. Add the premix described in step S1 into a twin-screw extruder through the main feeding port, feed the modified glass fiber into the twin-screw extruder through the side feeding port for melt blending, and extrude and granulate to obtain a low-warpage polypropylene composition; the temperature of the twin-screw extruder is 80-120°C in zone 1, 180-200°C in zones 2-5, and 200-230°C in other zones; the screw aspect ratio of the twin-screw extruder is (36-48):1.

[0085] Table 2 Amount of each component in the low warpage polypropylene composition in Examples 7 to 14 (unit: weight parts)

[0086]

[0087] Table 3 Amount of each component in the low warpage polypropylene composition in Comparative Examples 5 to 9 (unit: weight parts)

[0088]

[0089] Performance Testing

[0090] 1. Test methods

[0091] (1) Mechanical properties test: The polypropylene compositions prepared in the above examples and comparative examples were injection molded into 80 mm*10 mm*4 mm specimens, and impact properties were tested with reference to ISO 180-2019;

[0092] (2) Warpage performance test: The polypropylene compositions prepared in the above embodiments and comparative examples were injection molded into 210 mm*150 mm*3 mm specimens, with the gate of the specimens in the middle of the side of the specimens. The specimens were left standing at room temperature for 24 hours, and the height of the arched surface of the specimens was tested using a Leica microscope. The larger the height value, the more serious the warpage.

[0093] (3) Dimensional stability test: The polypropylene compositions prepared in the above examples and comparative examples were injection molded into tensile specimens of 115 mm*10 mm*4 mm, and the linear expansion coefficient at -30 to 100°C was tested according to ISO 11359-2:1999 standard. The smaller the linear expansion coefficient, the more stable the dimension.

[0094] 2. Test results

[0095] The test results of the polypropylene compositions prepared in the above examples and comparative examples are shown in Table 4.

[0096] Table 4 Test results of various embodiments and comparative examples

[0097] Test items <![CDATA[Impact performance (kJ / m 2 )]]> Warpage(cm) Linear expansion coefficient (μm / (m·℃)) Example 7 20 0.22 40 Example 8 15 0.40 45 Example 9 16 0.45 60 Example 10 12 0.43 70 Embodiment 11 19 0.51 42 Example 12 19 0.31 44 Example 13 9 3.52 90 Embodiment 14 18 0.47 35 Comparative Example 5 5 6.04 95 Comparative Example 6 4 2.12 100 Comparative Example 7 3 10.26 110 Comparative Example 8 6 9.10 105 Comparative Example 9 3 11.08 120

[0098] It can be seen from Table 4 that the low-warpage polypropylene composition prepared by the present invention has low warpage, good dimensional stability, and good mechanical properties. Specifically, the impact performance is not less than 9 kJ / m 2 , the warpage is not higher than 3.5cm, and the linear expansion coefficient is not higher than 90μm / (m·℃).

[0099] It can be seen from Examples 7 to 10 that when the content of the modified glass fiber surface modifier is 4 to 6 wt%, the low warpage polypropylene composition has better comprehensive performance and the impact performance is not less than 15 kJ / m 2 , the warpage is not higher than 0.4cm, and the linear expansion coefficient is not higher than 50μm / (m·℃).

[0100] It can be seen from Comparative Examples 5 and 6 that if the modifier content in the modified glass fiber is too high, the modifier is difficult to disperse during processing and the beneficial effect cannot be achieved; since the melt strength of glass fiber reinforced polypropylene is relatively large, when the modifier content is too low, the orientation of the glass fiber cannot be changed and the warpage cannot be improved.

[0101] It can be seen from Comparative Examples 7 and 8 that if other substances are used to replace the modifier in the present invention, the function of the modifier in the present invention cannot be achieved, and the comprehensive performance of the obtained polypropylene composition is significantly reduced.

[0102] It can be seen from Comparative Example 9 that if the glass fiber and the modifier are directly mixed with the polypropylene resin and extruded, the performance of the obtained polypropylene composition becomes extremely poor because the modifier cannot be evenly dispersed.

[0103] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A modified glass fiber, characterized in that: The surface of the glass fiber is coated with a modifier, which is an acrylate-acrylic amide polymer; the content of the modifier accounts for 2-8wt% of the modified glass fiber.

2. The modified glass fiber according to claim 1, characterized in that: The content of the modifier accounts for 4-6wt% of the modified glass fiber.

3. The modified glass fiber according to claim 1, characterized in that: The average length of the modified glass fiber is 3 to 7 mm.

4. A method for preparing the modified glass fiber according to any one of claims 1 to 3, characterized in that: The steps include: The modifier and glass fiber are mixed, stirred for reaction for 18 to 28 hours, and filtered and dried to obtain the product.

5. A low warpage polypropylene composition, characterized in that: The composition comprises the following components calculated by weight: 50-90 parts of polypropylene resin; 10 to 50 parts of the modified glass fiber according to any one of claims 1 to 3; 0.5 to 4 parts of additives.

6. The low warpage polypropylene composition according to claim 5, characterized in that: The polypropylene resin has a melt flow rate of 3 to 100 g / 10 min at 230° C. and 2.16 kg.

7. The low warpage polypropylene composition according to claim 5, characterized in that: The polypropylene resin is homopolypropylene and / or copolymer polypropylene.

8. The low warpage polypropylene composition according to claim 5, characterized in that: The auxiliary agent includes one or more of an antioxidant, a weathering agent or a lubricant.

9. A method for preparing the low-warpage polypropylene composition according to any one of claims 5 to 8, characterized in that: The steps include: S1. The polypropylene resin and the additive are mixed uniformly to obtain a premix; S2. The premix described in S1 is fed through the main feeding port, and the modified glass fiber is fed through the side feeding port for melt blending, extrusion granulation to obtain a low-warpage polypropylene composition.

10. Use of the low warpage polypropylene composition according to any one of claims 5 to 8 in the preparation of automotive parts materials.

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