阅读说明：本技术 一种高强度、高抗冲非连续纤维增强热塑性复合材料预制体及其制备方法 (High-strength and high-impact-resistance discontinuous fiber reinforced thermoplastic composite material preform and preparation method thereof ) 是由 陈大华 陈金伟 何亮 喻慧文 庄文柳 刘青山 李建刚 于 2019-04-29 设计创作，主要内容包括：本发明公开了一种高强度、高抗冲非连续纤维增强热塑性复合材料预制体及其制备方法。所述制备方法包括以下步骤：将热塑性树脂、助剂和连续纤维通过熔融浸渍的方式复合成为厚度为0.1～0.2mm的连续纤维增强热塑性片材；将连续片材分切为长宽尺寸为(10～50mm)×(5～10mm)的小片；将分切好的小片材混合均匀以保持纤维分布的各向同性；加热使混匀后的小片材熔融；然后通过低剪切的混炼设备进行混炼,使纤维达到各向同性分布；将处于熔融状态的复合物熔体通过冷压成厚度1～5mm的一定宽度的片材。与现有的制备方法相比,本发明制备出的非连续纤维增强热塑性复合材料各向同性更好,冲击强度更高。(The invention discloses a high-strength and high-impact-resistance discontinuous fiber reinforced thermoplastic composite material preform and a preparation method thereof. The preparation method comprises the following steps: compounding thermoplastic resin, an auxiliary agent and continuous fibers into a continuous fiber reinforced thermoplastic sheet with the thickness of 0.1-0.2 mm in a melting and dipping mode; cutting the continuous sheet into small pieces with the length and width of (10-50 mm) × (5-10 mm); uniformly mixing the cut small sheets to keep the isotropy of fiber distribution; heating to melt the uniformly mixed small slices; then mixing the fibers by low-shear mixing equipment to enable the fibers to be distributed isotropically; and cold-pressing the compound melt in the molten state into a sheet with a certain width and the thickness of 1-5 mm. Compared with the existing preparation method, the discontinuous fiber reinforced thermoplastic composite material prepared by the invention has better isotropy and higher impact strength.)

1. A preparation method of a high-strength and high-impact-resistance discontinuous fiber reinforced thermoplastic composite material preform is characterized by comprising the following steps:

(1) Compounding thermoplastic resin, an auxiliary agent and continuous fibers into a continuous fiber reinforced thermoplastic sheet with the thickness of 0.1-0.2 mm in a melting and dipping mode;

(2) cutting the continuous sheet into small sheets with the length and width of (10-50 mm) × (5-10 mm);

(3) uniformly mixing the cut small sheets to keep the isotropy of fiber distribution;

(4) heating to melt the uniformly mixed small slices;

(5) then mixing the materials by low-shear mixing equipment to improve the uniformity of the materials;

(6) and cold-pressing the compound melt in the molten state into a sheet with the thickness of 1-5 mm.

2. The preparation method of the high-strength high-impact discontinuous fiber reinforced thermoplastic composite preform according to claim 1, wherein in the step (1), the mass percentages of the thermoplastic plastic, the auxiliary agent and the continuous fiber are respectively 28-65%, 0.1-5% and 30-70%.

3. The method for preparing a high-strength high-impact discontinuous fiber-reinforced thermoplastic composite preform according to claim 1, wherein the thermoplastic resin in step (1) comprises one or more of PE resin, PP resin, PA resin, PC resin, PMMA resin, PBT resin and PPS resin.

4. The method for preparing a high-strength high-impact discontinuous fiber-reinforced thermoplastic composite preform according to claim 1, wherein the auxiliary agent in step (1) comprises one or more of an antioxidant, a lubricant and a compatilizer.

5. The method for preparing the high-strength high-impact discontinuous fiber reinforced thermoplastic composite preform according to claim 1, wherein the continuous fiber in the step (1) comprises more than one of carbon fiber, glass fiber, aramid fiber and basalt fiber.

6. The method for preparing a high-strength high-impact discontinuous fiber-reinforced thermoplastic composite preform according to claim 1, wherein the melt impregnation in the step (1) is performed by a twin-screw extruder, and the thermoplastic resin and the auxiliary agent are uniformly mixed, melted by the twin-screw extruder, and then fed into the impregnation die and the continuous fiber for melt impregnation.

7. The method for preparing a high-strength high-impact non-continuous fiber-reinforced thermoplastic composite preform according to claim 1, wherein the mixing in the step (3) is ordinary mixing.

8. The method for preparing a high-strength high-impact discontinuous fiber reinforced thermoplastic composite preform according to claim 1, wherein the heating in step (4) is infrared heating or continuous oven heating.

9. The method for preparing a high-strength high-impact non-continuous fiber-reinforced thermoplastic composite preform according to claim 1, wherein the low-shear mixing device of step (5) comprises a pin-type single-screw extruder or a low-shear twin-screw extruder, and the low-shear rate is not higher than 10²In seconds.

10. A high-strength, high-impact non-continuous fiber-reinforced thermoplastic composite preform prepared by the method of any one of claims 1 to 9.

Technical Field

The invention belongs to the technical field of high polymer materials, and relates to a high-strength and high-impact-resistance discontinuous fiber reinforced thermoplastic composite material preform and a preparation method thereof.

Background

There are two main categories of fiber reinforced thermoplastic composites: continuous fiber reinforced thermoplastic Composites (CFRTP) and discontinuous fiber reinforced thermoplastic composites; non-continuous fiber reinforced thermoplastic composites are further classified into three categories: short fiber reinforced thermoplastic composites (SFT), long fiber reinforced thermoplastic composites (LFT), and fiber mat reinforced thermoplastic composites (GMT).

Continuous fiber reinforced thermoplastic Composites (CFRTP) have strength and impact properties comparable to metals, but suffer from poor formability and processability, and low freedom of design of product structure; although the discontinuous fiber reinforced thermoplastic composite materials SFT, LFT and GMT have good molding processability, the impact resistance (notch impact strength) is too low and is far from metal, so that the method is difficult to realize that steel is replaced by plastic in a true sense.

In the related patents of SFT, such as publication No. CN101311222B, the patent application entitled "a high impact fiber reinforced engineering plastic and preparation method", a twin-screw co-extrusion preparation process is used, the tensile strength of which is only 111.1 MPa; the notched impact strength is only 22.2kJ/m²(ii) a For example, in patent application publication No. CN10271907B entitled "a fiber reinforced polycarbonate resin having high impact strength and method for preparing the same", a twin-screw co-extrusion preparation process is employed, the tensile strength of which is only 114.5 MPa; the notched impact strength was only 118.1J/m (about 12 kJ/m) ²) (ii) a For example, in patent application with publication number CN106751765A entitled "a wear-resistant high impact nylon composite material and its preparation method and application", a twin-screw blending extrusion preparation process is adopted, and the tensile strength is only 151MPa at most; the notched impact strength was only 11.9kJ/m²。

In patents related to LFT, such as patent application publication No. CN105273316A entitled "A high impact Long fiber reinforced Polyethylene (PE) composite and method of manufacture", a melt impregnation process is used to produce a composite material having tensile strengthThe highest degree is only 130 MPa; the maximum notch impact strength is only 40kJ/m²(ii) a For example, in patent application publication No. CN 108219287A entitled "a low warpage high impact resistant long fiber reinforced polypropylene composite material and method for preparing the same", a melt impregnation preparation process is adopted, and the tensile strength is only 86.4MPa at most; the notched impact strength was only 31.1kJ/m²。

In patent application publication No. CN10931850A entitled "A discontinuous large linear length fiber reinforced thermoplastic composite material compression molded preform and method for making same", CFRTP continuous sheet material is cut into discontinuous sheet material with certain length and width and then pressed into preform, the impact strength is improved significantly, but the anisotropy is very obvious, the impact strength in different directions is about doubled, see Table 1 for details.

Table 1:

as can be seen from the above patent applications for non-continuous fiber-reinforced thermoplastic composites, there is currently no composite material having a tensile strength of more than 150MPa and a notched impact strength of more than 150kJ/m in all directions²The high strength, high impact discontinuous fiber reinforced thermoplastic of (1).

Disclosure of Invention

The invention aims to provide a preparation method of a high-strength and high-impact-resistance discontinuous fiber reinforced thermoplastic composite material preform, and aims to solve the problems of insufficient strength and impact resistance and obvious anisotropy of a discontinuous fiber reinforced thermoplastic composite material.

Another object of the present invention is to provide a high-strength, high-impact-resistance discontinuous fiber-reinforced thermoplastic composite preform prepared by the above preparation method.

The purpose of the invention is realized by the following technical scheme:

a preparation method of a high-strength and high-impact-resistance discontinuous fiber reinforced thermoplastic composite material preform comprises the following steps:

(1) compounding thermoplastic resin, an auxiliary agent and continuous fibers into a continuous fiber reinforced thermoplastic sheet (CFRTP) with the thickness of 0.1-0.2 mm in a melting and dipping mode;

(2) cutting the continuous sheet into small sheets with the length and width of (10-50 mm) × (5-10 mm);

(3) Uniformly mixing the cut small sheets to keep the isotropy of fiber distribution;

(4) heating to melt the uniformly mixed small slices;

(5) then mixing the materials by low-shear mixing equipment to improve the uniformity of the materials;

(6) and cold-pressing the compound melt in the molten state into a sheet with a certain width and a thickness of 1-5 mm, wherein the sheet is the high-strength high-impact discontinuous fiber reinforced thermoplastic composite material preform.

In the step (1), the thermoplastic resin accounts for 28-65% by mass, the auxiliary agent accounts for 0.1-5% by mass, and the continuous fiber accounts for 30-70% by mass.

The thermoplastic resin in the step (1) comprises more than one of PE resin, PP resin, PA resin, PC resin, PMMA resin, PBT resin, PPS resin and the like.

The auxiliary agent in the step (1) comprises more than one of an antioxidant, a compatilizer, a lubricant and the like.

The continuous fiber in the step (1) comprises more than one of carbon fiber, glass fiber, aramid fiber and basalt fiber.

The melting impregnation in the step (1) is realized through a double-screw extruder, the thermoplastic resin and the auxiliary agent are uniformly mixed, and then the mixture is melted through the double-screw extruder and enters an impregnation die head to be melt impregnated with the continuous fibers.

The mixing in the step (3) is common mixing.

The heating in the step (4) is infrared heating or continuous oven heating.

The mixing time in the step (5) is 1-5 minutes.

The low-shear mixing device in the step (5) comprises a pin-type single-screw extruder or a low-shear twin-screw extruder, and the low-shear is generally referred to asShear rate of not higher than 10²In seconds.

Compared with the prior art, the invention has the following advantages and effects:

compared with the existing preparation method, the discontinuous fiber reinforced thermoplastic composite material preform prepared by the invention has better uniformity, better isotropy and higher impact strength, and the notch impact strength in each direction exceeds 150kJ/m²。

Detailed Description

The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.

The invention relates to a preparation method of a high-strength and high-impact-resistance discontinuous fiber reinforced thermoplastic composite preform, which is suitable for thermoplastic plastics such as PE (polyethylene) resin, PP (polypropylene) resin, PA (polyamide) resin, PC (polycarbonate) resin, PBT (polybutylene terephthalate), PMMA (polymethyl methacrylate), PPS (polyphenylene sulfide) and the like, and comprises the following specific preparation steps of:

1. preparation of high-strength and high-impact-resistance discontinuous fiber reinforced PP composite material preform

Compounding PP resin, an auxiliary agent and continuous fibers (28-65 wt% of PP resin, 0.1-5 wt% of auxiliary agent and 30-70 wt% of continuous fibers) into a continuous fiber reinforced thermoplastic sheet (CFRTP) with the thickness of 0.1-0.2 mm in a melting impregnation mode, wherein the melting impregnation temperature is set to 230-280 ℃;

cutting the continuous sheet into small sheets with the length and width of (10-50 mm) × (5-10 mm);

uniformly mixing the cut small sheets to keep the isotropy of fiber distribution;

melting the small sheet material by infrared or other rapid heating modes;

fifthly, performing heat preservation mixing for 1-5 minutes by low-shear mixing equipment;

and sixthly, pressing the compound melt in the molten state into a sheet with a certain width and the thickness of 1-5mm by using a continuous double-belt press, wherein the temperature of the continuous double-belt press is set to be 175-200 ℃.

2. Preparation of high-strength and high-impact-resistance discontinuous fiber reinforced PA6 composite material preform

Compounding PA6 resin, an auxiliary agent and continuous fibers (28-65 wt% of PA6 resin, 0.1-5 wt% of auxiliary agent and 30-70 wt% of continuous fibers) into a continuous fiber reinforced thermoplastic sheet (CFRTP) with the thickness of 0.1-0.2 mm in a melt impregnation mode, wherein the melt impregnation temperature is set to be 260-320 ℃;

Cutting the continuous sheet into small sheets with the length and width of (10-50 mm) × (5-10 mm);

uniformly mixing the cut small sheets to keep the isotropy of fiber distribution;

melting the small sheet material by infrared or other rapid heating modes;

fifthly, performing heat preservation mixing for 1-5 minutes by low-shear mixing equipment;

sixthly, pressing the compound melt in the molten state into a sheet with a certain width and the thickness of 1-5mm by a continuous double-belt press, wherein the temperature of the continuous double-belt press is set to be 240-260 ℃.

3. Preparation of high-strength and high-impact-resistance discontinuous fiber reinforced PA66 composite material preform

Compounding PA66 resin, an auxiliary agent and continuous fibers (28-65 wt% of PA66 resin, 0.1-5 wt% of auxiliary agent and 30-70 wt% of continuous fibers) into a continuous fiber reinforced thermoplastic sheet (CFRTP) with the thickness of 0.1-0.2 mm in a melt impregnation mode, wherein the melt impregnation temperature is set to 270-330 ℃;

cutting the continuous sheet into small sheets with the length and width of (10-50 mm) × (5-10 mm);

uniformly mixing the cut small sheets to keep the isotropy of fiber distribution;

melting the small sheet material by infrared or other rapid heating modes;

Fifthly, performing heat preservation mixing for 1-5 minutes by low-shear mixing equipment;

sixthly, pressing the compound melt in the molten state into a sheet with a certain width and the thickness of 1-5mm by using a continuous double-belt press, wherein the temperature of the continuous double-belt press is set to be 270-290 ℃.

4. Preparation of high-strength and high-impact-resistance discontinuous fiber reinforced PC composite material preform

Compounding a PC resin, an auxiliary agent and continuous fibers (28-65 wt% of the PC resin, 0.1-5 wt% of the auxiliary agent and 30-70 wt% of the continuous fibers) into a continuous fiber reinforced thermoplastic sheet (CFRTP) with the thickness of 0.1-0.2 mm by a melt impregnation mode, wherein the melt impregnation temperature is set to be 300-330 ℃;

cutting the continuous sheet into small sheets with the length and width of (10-50 mm) × (5-10 mm);

uniformly mixing the cut small sheets to keep the isotropy of fiber distribution;

melting the small sheet material by infrared or other rapid heating modes;

fifthly, performing heat preservation mixing for 1-5 minutes by low-shear mixing equipment;

and sixthly, pressing the compound melt in the molten state into a sheet with a certain width and the thickness of 1-5mm by using a continuous double-belt press, wherein the temperature of the continuous double-belt press is set to be 270-300 ℃.