阅读说明：本技术 一种非连续纤维增强热塑复合材料预制片材及其制备方法 (Discontinuous fiber reinforced thermoplastic composite material prefabricated sheet 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：本发明公开了一种非连续纤维增强热塑复合材料预制片材及其制备方法。制备方法包括以下步骤：将热塑性塑脂、助剂和连续纤维通过熔融浸渍复合成连续纤维增强热塑性片材；将连续纤维增强热塑性片材在线分切为10-30mm宽的连续窄片材；将连续窄片材在线加热熔融；将熔融后的材料导入低剪切的双螺杆挤出机剪短纤维并实现分纤维的均匀分布混合；从双螺杆挤出机的狭缝型机头挤出的熔体经带冷却功能的连续压延设备压成而成厚度1-5mm的板材即为所述非连续纤维增强热塑复合材料预制片材。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在兼具高强度高抗冲、各向同性好的同时,整线可实现连续化生产,具有更高的生产效率。(The invention discloses a discontinuous fiber reinforced thermoplastic composite material prefabricated sheet 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 material through melting and dipping; cutting the continuous fiber reinforced thermoplastic sheet into continuous narrow sheets with the width of 10-30mm on line; heating and melting the continuous narrow sheet on line; introducing the melted material into a low-shear double-screw extruder to shear fibers and realize uniform distribution and mixing of the fibers; and (3) pressing the melt extruded from the slit type head of the double-screw extruder into a plate with the thickness of 1-5mm by using continuous rolling equipment with a cooling function, namely the discontinuous fiber reinforced thermoplastic composite material prefabricated sheet. Compared with the existing preparation method, the discontinuous fiber reinforced thermoplastic composite material prepared by the invention has high strength, high impact resistance and good isotropy, and the whole line can realize continuous production and has higher production efficiency.)

1. A preparation method of a discontinuous fiber reinforced thermoplastic composite material prefabricated sheet is characterized by comprising the following steps:

(1) compounding thermoplastic resin, an auxiliary agent and continuous fibers into a continuous fiber reinforced thermoplastic sheet material in a melting impregnation mode;

(2) cutting the continuous fiber reinforced thermoplastic sheet into continuous narrow sheets with the width of 10-30 mm on line;

(3) heating and melting the continuous narrow sheet on line;

(4) introducing the melted material into a low-shear double-screw extruder to shear fibers and realize uniform distribution and mixing of the fibers;

(5) and pressing the melt extruded from the slit type head of the double-screw extruder into a plate with the thickness of 1-5 mm by using continuous rolling equipment with a cooling function, namely the discontinuous fiber reinforced thermoplastic composite material prefabricated sheet.

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

3. The method for preparing a discontinuous fiber reinforced thermoplastic composite material precast sheet according to claim 1, wherein the thermoplastic resin in the step (1) comprises more than one of PE resin, PP resin, PA resin, PC resin, PMMA resin, PBT resin and PPS resin.

4. The method for preparing the non-continuous fiber-reinforced thermoplastic composite material preformed sheet according to claim 1, wherein the auxiliary agent in the step (1) comprises more than one of a thermal stabilizing auxiliary agent, a compatilizer, a lubricant and an antioxidant.

5. The method for preparing a non-continuous fiber-reinforced thermoplastic composite preformed sheet according to claim 1, wherein the continuous fibers in the step (1) comprise one or more of carbon fibers and glass fibers.

6. The method for preparing the discontinuous fiber reinforced thermoplastic composite material prefabricated sheet material as claimed in claim 1, wherein the melting impregnation in the step (1) is realized by a twin-screw extruder, the thermoplastic resin and the auxiliary agent are uniformly mixed, and then the mixture is melted by the twin-screw extruder and enters an impregnation die head to melt-impregnate the continuous fiber.

7. The method for preparing the non-continuous fiber-reinforced thermoplastic composite preformed sheet according to claim 1, wherein the on-line heating in the step (3) is infrared heating or continuous oven heating.

8. The method for preparing a non-continuous fiber-reinforced thermoplastic composite preformed sheet according to claim 1, wherein the continuous calendaring equipment with cooling function in the step (5) comprises a double-roller calendar with cooling function or a double-belt continuous press.

9. A non-continuous fiber-reinforced thermoplastic composite preform sheet produced by the production method according to any one of claims 1 to 8.

Technical Field

The invention belongs to the technical field of high polymer materials, and particularly relates to a discontinuous fiber reinforced thermoplastic composite material prefabricated sheet 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/m ²(ii) a For example, in patent application publication No. CN10271907B entitled "A fiber reinforced polycarbonate resin having high impact Strength and method for producing the same", the use ofThe tensile strength of the double-screw blending extrusion preparation process 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 preparation", a melt impregnation preparation process is used, which has a tensile strength of only 130MPa at most; 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/m ²。

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. In addition, the cutting step of the preparation method of this patent results in low production efficiency.

Table 1:

disclosure of Invention

The invention aims to provide a preparation method of a discontinuous fiber reinforced thermoplastic composite material prefabricated sheet, and solves the problems of insufficient impact resistance, obvious anisotropy and low production efficiency of the discontinuous fiber reinforced thermoplastic composite material.

Another object of the present invention is to provide a non-continuous fiber-reinforced thermoplastic composite preform sheet obtained by the above-mentioned production method.

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

a preparation method of a discontinuous fiber reinforced thermoplastic composite material prefabricated sheet material comprises the following steps:

(1) compounding a thermoplastic resin, an auxiliary agent and continuous fibers into a continuous fiber reinforced thermoplastic sheet (CFRTP) by means of melt impregnation;

(2) Cutting the continuous fiber reinforced thermoplastic sheet into continuous narrow sheets with the width of 10-30 mm on line;

(3) heating and melting the continuous narrow sheet on line;

(4) introducing the melted material into a low-shear double-screw extruder to shear fibers and realize uniform distribution and mixing of the fibers;

(5) and pressing the melt extruded from the slit type head of the double-screw extruder into a plate with the thickness of 1-5 mm by using continuous rolling equipment with a cooling function, namely the discontinuous fiber reinforced thermoplastic composite material prefabricated sheet.

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 one or more of a thermal stabilizing auxiliary agent, a compatilizer, a lubricant, an antioxidant and the like.

The continuous fiber in the step (1) comprises more than one of carbon fiber and glass 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 and continuous fibers for melt impregnation.

And (3) the online heating is infrared heating or continuous oven heating.

The continuous rolling equipment with the cooling function in the step (5) comprises a double-roller rolling machine or a double-belt continuous pressing machine with the cooling function.

The low shear of the invention means that the screw elements with stronger shearing action are used as little as possible, and the rotating speed of the screw is set to be lower, generally below 200rpm, so as to achieve the aim of shearing the fibers but not cutting too short.

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

compared with the existing preparation method, the discontinuous fiber reinforced thermoplastic composite material prepared by the process route has high strength, high impact resistance and good isotropy, and the whole line can realize continuous production and has higher production efficiency.

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 discontinuous fiber reinforced thermoplastic composite material prefabricated sheet, which is suitable for thermoplastic plastics such as PE (polyethylene) resin, PP (polypropylene) resin, PA (polyamide) resin, PC (polycarbonate) resin 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 prefabricated sheet

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) in a melt impregnation mode, wherein the melt impregnation temperature is set to be 230-280 ℃;

secondly, cutting the continuous sheet into continuous narrow sheets with the width of 10-30 mm on line;

thirdly, the continuous sheet material reaches a molten state by using an infrared or other on-line rapid heating mode;

fourthly, guiding the melted material into a low-shear double-screw extruder, cutting short the fibers and realizing uniform distribution and mixing of the fibers; setting the screw extrusion temperature to be 200-280 ℃, and setting the screw rotation speed to be 50-200 rpm;

and fifthly, pressing the melt extruded from the slit type head of the double-screw extruder into a discontinuous fiber reinforced thermoplastic composite material prefabricated sheet with the thickness of 1-5mm by using continuous calendering equipment with a cooling function.

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

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) in a melt impregnation mode, wherein the melt impregnation temperature is set to be 260-320 ℃;

Secondly, cutting the continuous sheet into continuous narrow sheets with the width of 10-30 mm on line;

thirdly, the continuous sheet material reaches a molten state by using an infrared or other on-line rapid heating mode;

fourthly, guiding the melted material into a low-shear double-screw extruder, cutting short the fibers and realizing uniform distribution and mixing of the fibers; setting the extrusion temperature of the screw to 240-300 ℃, and setting the rotating speed of the screw to 50-200 rpm;

and fifthly, pressing the melt extruded from the slit type head of the double-screw extruder into a discontinuous fiber reinforced thermoplastic composite material prefabricated sheet with the thickness of 1-5mm by using continuous calendering equipment with a cooling function.

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

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) in a melt impregnation mode, wherein the melt impregnation temperature is set to be 270-330 ℃;

secondly, cutting the continuous sheet into continuous narrow sheets with the width of 10-30 mm on line;

thirdly, the continuous sheet material reaches a molten state by using an infrared or other rapid heating mode;

fourthly, guiding the melted material into a low-shear double-screw extruder, cutting short the fibers and realizing uniform distribution and mixing of the fibers; setting the screw extrusion temperature to be 270-320 ℃, and setting the screw rotation speed to be 500-200 rpm;

And fifthly, pressing the melt extruded from the slit type head of the double-screw extruder into a discontinuous fiber reinforced thermoplastic composite material prefabricated sheet with the thickness of 1-5mm by using continuous calendering equipment with a cooling function.