CN115923209A - Continuous fiber cloth/UHMWPE composite material and double-layer co-extrusion molding process thereof - Google Patents

Abstract

The invention relates to a continuous fiber cloth/UHMWPE composite material and a double-layer co-extrusion molding process thereof, which comprises the following steps: extruding an ultra-high molecular weight polyethylene material through a single screw extruder, heating the ultra-high molecular weight polyethylene material to a temperature higher than the melting temperature at a feeding section of the screw extruder, conveying a melt into a mold forming section, and performing melt-compression molding in the mold forming section to prepare a melt parison; the molding method comprises extrusion molding, injection molding and compression molding; the method comprises the steps of firstly, respectively pre-attaching films to two sides of the surface of the fiber cloth, then enabling the fiber cloth to penetrate through a die through a specific cavity, and forming composite co-extrusion with a melt blank before a cooling section to form the continuous fiber cloth/UHMWPE composite material. Compared with the prior art, the invention effectively solves the problems of size accuracy, temperature resistance and cutting resistance of the existing UHMWPE product, and promotes the development of the UHMWPE product industry.

Description

A continuous fiber cloth/UHMWPE composite material and its double-layer co-extrusion molding process

technical field

The invention relates to the field of polymer processing and molding, in particular to a continuous fiber cloth/UHMWPE composite material and a double-layer co-extrusion molding process thereof.

Background technique

Ultra-high molecular weight polyethylene (UHMWPE) is polyethylene (PE) with a viscosity average molecular weight greater than 1.5 million. It is a new type of thermoplastic engineering plastic. Due to its long molecular chain and extremely high molecular weight, it has excellent mechanical properties, impact resistance, and wear resistance Loss, self-lubrication, chemical corrosion resistance and other properties. UHMWPE is the plastic with the best wear resistance that has been found so far, so its plates, pipes, and profiles are widely used in petrochemical, machinery, textile, paper, mining, grain processing, and sports equipment and other fields, among which large packaging containers And pipelines are the most widely used. In addition, based on the excellent physiological inertia of UHMWPE, it has been used in the field of medicine and health as heart valves, orthopedic parts, artificial joints, etc.

The workpiece made of UHMWPE has high strength and high impact resistance, and it still maintains excellent toughness and strength even in the environment of -40°C. However, UHMWPE has an obvious defect, which is poor in high temperature resistance and wear resistance. Scratch resistant. With the wide application of UHMWPE products, the shape and size of the products are also diverse, and the requirements for dimensional accuracy, high temperature resistance and cutting resistance of the products are also constantly improving, especially for some special-shaped parts, such as guide rails , sliders, gears, etc. However, due to the high shrinkage rate of about 2-3%, it is easy to produce dimensional instability such as warping, ellipse, and local uneven shrinkage during the molding process.

Contents of the invention

The object of the present invention is to provide a continuous fiber cloth/UHMWPE composite material and its double-layer co-extrusion molding process in order to overcome at least one of the above-mentioned defects in the prior art. It effectively solves the problems of dimensional accuracy, temperature resistance and cutting resistance of existing UHMWPE products, and promotes the development of UHMWPE product industry.

The purpose of the present invention can be achieved through the following technical solutions:

The present invention uses the fiber cloth/UHMWPE double-layer co-extrusion molding process to design a suitable mold according to the shape, thickness and application requirements of the product, design a reasonable temperature distribution, and form a stepped temperature distribution to accurately adjust the size of the product and select a suitable fiber cloth to achieve anti-cutting and improve the temperature resistance of UHMWPE products, the specific plan is as follows:

A double-layer co-extrusion molding process of continuous fiber cloth/UHMWPE composite material, the process comprises the following steps:

The ultra-high molecular weight polyethylene matrix material is extruded through a single-screw extruder. In the feeding section of the screw extruder, the ultra-high molecular weight polyethylene material is heated above the melting temperature, and then the melt is transported into the mold forming section. Melt-compression molding is carried out in the molding section of the mold to prepare a melt parison; molding methods include extrusion molding, injection molding, and compression molding;

Firstly, the two sides of the surface of the fiber cloth are pre-laminated with films, and then the fiber cloth is passed through the specific cavity 1 through the pre-compound heating roller, and the composite co-extrusion is formed with the melt parison before the cooling section to form a continuous fiber cloth/UHMWPE The composite material is then cooled and shaped through a specific cavity 2, and pulled out by a tractor.

Further, the fiber cloth is a fiber cloth prepared by blending ultra-high molecular weight polyethylene fibers and heat-resistant fibers. Other fiber blending is mainly to improve the shortcoming of ultra-high molecular weight polyethylene fiber that is not resistant to high temperature. Generally, the temperature resistance of ultra-high molecular weight polyethylene fiber is 120-140°C, but the temperature resistance of aramid fiber, carbon fiber, glass fiber, etc. is all at 200°C. above. Ultra-high molecular weight polyethylene fiber has high strength and high modulus, excellent wear resistance and cut resistance. After blending, it can increase the use temperature and highlight excellent wear resistance and cut resistance.

Further, the ratio of the area of the fiber cloth occupied by the ultra-high molecular weight polyethylene fiber to the temperature-resistant fiber is (2-5):1, the surface density of the fiber cloth is 60-200g/m ² , and the blending adopts plain weave or Twill weave.

Further, the temperature-resistant fiber is a fiber with a temperature resistance not lower than 200°C, including one of polypropylene fiber, nylon fiber, aramid fiber, carbon fiber, glass fiber, polyester fiber, viscose fiber or acrylic fiber or Several types; the ultra-high molecular weight polyethylene fiber has a strength of 25-40cN/dtex and a fineness of 50-1600D, preferably, a fiber strength of 30-35cN/dtex and a fineness of 500-1000D.

Further, the molecular weight of the ultra-high molecular weight polyethylene is 1 million to 6 million.

Further, the specific steps described are:

(1) Extrude the ultra-high molecular weight polyethylene base material through a single-screw extruder. In the feeding section of the screw extruder, the ultra-high molecular weight polyethylene material is heated above the melting temperature, and then the melt is transported into the mold for molding section, which is melt-compressed in the mold forming section to prepare a melt parison;

(2) Pre-laminate the film on both sides of the surface of the fiber cloth, and then pass the fiber cloth through the specific cavity 1 through the pre-composite heating roller, and form a composite co-extrusion with the melt parison before the cooling section to form a continuous fiber The cloth/UHMWPE composite material is cooled and shaped through a specific cavity 2, and pulled out by a tractor.

Further, in step (1), the single-screw extrusion temperature is controlled to be 150-280°C and the temperature is gradually raised; the mold forming section is sequentially provided with a split section, a compression section and a shaping section, and the temperature is controlled to be 250-180°C in a stepwise manner. Cool down, where the diversion section is 235-280°C, the compression section is 200-235°C, and the shaping section is 150-200°C.

Further, in step (2), the specific cavity has a multi-point staged temperature control effect of internal and external measurements. The temperature inside the cavity is controlled at 150-180°C, and the temperature at the outside is controlled at 135-160°C; the temperature of the composite co-extrusion is 150-180°C, the compression ratio of the composite section is (1.1-1.8):1, and the specific cavity 1 template pressure is automatically adjusted and controlled by the pressure sensor.

Further, the film includes an ultra-high molecular weight polyethylene film and an EVA film. When laminating, a four-layer composite fiber cloth of ultra-high molecular weight polyethylene film/EVA film/fiber cloth/EVA film is formed, and the UHMWPE film is located in the cavity Outside, the thickness is 0.2-1mm, and the thickness of EVA film is 0.2-0.5mm.

A continuous fiber cloth/UHMWPE composite material prepared by the above-mentioned double-layer co-extrusion molding process.

Compared with the prior art, the present invention has the following advantages:

(1) The present invention designs a reasonable temperature distribution to form a stepped temperature distribution, and uses related temperature control equipment such as a mold temperature machine and a water chiller to accurately adjust the temperature difference, control the cooling rate and shrinkage rate of the material, and then achieve the purpose of accurately adjusting the size of the product;

(2) The present invention utilizes the blending of ultra-high molecular weight polyethylene fiber and other fibers, which has the high strength and high modulus of ultra-high molecular weight polyethylene fiber, excellent cutting resistance performance, excellent temperature resistance of fibers such as aramid fiber and carbon fiber, and composite On the surface of ultra-high-molecular-weight polyethylene products, the defects of ultra-high-molecular-weight polyethylene, such as wear resistance and scratch resistance, low temperature resistance and high temperature resistance, are improved, thereby extending the service life and scope of use of the product;

(3) The specific cavity of the present invention has functions such as extruding and shaping, adjusting shrinkage rate, and the like. The shape of the inner cavity of the cavity is the same as that of the previous die head, and it comes with the shape of the product. Generally speaking, most of the molded cavities are cooled and shaped, and they are rarely controllable, and the composite shrinkage rate of two or several materials can be controlled and adjusted during the composite process. The specific mold cavity of the present invention can controllably adjust the composite shrinkage rate of two or several materials in the composite process through a pressure sensor and a high and low temperature mold temperature controller.

Description of drawings

Fig. 1 is a schematic diagram of extrusion composite molding of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is carried out on the premise of the technical solution of the present invention, and the detailed implementation and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

A continuous fiber cloth/UHMWPE composite material and a double-layer co-extrusion molding process thereof, comprising the following steps:

(1) The ultra-high molecular weight polyethylene material is extruded through a single-screw extruder. In the feeding section of the screw extruder, the ultra-high molecular weight polyethylene material is heated above the melting temperature, and then the melt is transported into the mold forming section. In the molding section of the mold, it is melt-compressed to prepare a melt parison; the ultra-high molecular weight polyethylene fiber strength is 25-40cN/dtex, and the fineness is 50-1600D, preferably the fiber strength is 30-35cN/dtex, and the fineness is 500 -1000D. The matrix is ultra-high molecular weight polyethylene powder with a molecular weight of 1 million to 6 million. The single-screw extrusion temperature control is 150-280°C and the temperature is gradually raised; the mold forming section is equipped with a split section, a compression section and a shaping section in sequence, and its temperature control is 250-180°C. ℃, compression section 200-235℃, setting section 150-200℃.

(2) Both sides of the surface of the fiber cloth are pre-composited with ultra-high molecular weight polyethylene/EVA film to form a four-layer composite fiber cloth of ultra-high molecular weight polyethylene film/EVA film/fiber cloth/EVA film, and then pass the fiber cloth through a specific type The cavity passes through the mold, and forms a composite co-extrusion with the melt parison before the cooling section. The composite temperature is 150-180°C, and the compression ratio of the composite section (1.1-1.8): 1, thereby forming a co-extruded product. Fiber cloth is a fiber cloth prepared by one or several blends of ultra-high molecular weight polyethylene fibers and other fibers. Other fibers include one or more of polypropylene fibers, nylon fibers, aramid fibers, carbon fibers, glass fibers, polyester fibers, viscose fibers, and acrylic fibers. Weave UHMWPE fiber with other fibers in plain weave or twill weave. The area ratio of UHMWPE fiber to other fibers is (2-5):1, and the surface density of the fiber cloth is 60-200g/m ² . The specific cavity has a multi-point staged temperature control effect of internal and external measurements. The temperature inside the cavity is controlled at 150-180°C, and the temperature at the outside is controlled at 135-160°C.

Example 1

A continuous fiber cloth/UHMWPE composite material and its double-layer co-extrusion molding process, extruding ultra-high molecular weight polyethylene profiles, raw material molecular weight 2 million, first heating the ultra-high molecular weight polyethylene material to a temperature above the melting temperature, The melt is extruded into a high-pressure melt through the compression section of the mold, and the fiber cloth made by blending ultra-high molecular weight polyethylene fiber and aramid fiber according to the area ratio of 2:1, the surface density of the fiber cloth is 60g/m ² , the surface Composite ultra-high molecular weight polyethylene film/EVA film on both sides, the thickness of the outer ultra-high molecular weight polyethylene film is 1mm, and the thickness of the inner EVA film is 0.2mm, and then compound with the high-pressure melt in the shaping section, the compounding temperature is 180 ℃, compounding The compression ratio of the stage is 1.5:1, and then it is cooled and formed into a finished product. The molding section of the mold is divided into a split section, a compression section, and a shaping section, and the heating temperature ranges are 250°C, 210°C, and 180°C. The temperature inside the cavity is controlled at 160°C, and the temperature outside the cavity is controlled at 150°C. The mechanical properties of extruded products are shown in attached table 1.

Example 2

A continuous fiber cloth/UHMWPE composite material and its double-layer co-extrusion molding process, extruding ultra-high molecular weight polyethylene profiles, the molecular weight of raw materials is 3.5 million, first heating the ultra-high molecular weight polyethylene material to a temperature above the melting temperature, The melt is extruded into a high-pressure melt through the compression section of the mold, and the fiber cloth is made by blending ultra-high molecular weight polyethylene fiber and nylon fiber according to the area ratio of 5:1. The surface density of the fiber cloth is 90g/m ² , and the surface is double Composite ultra-high molecular weight polyethylene film/EVA film on the side, the thickness of the outer ultra-high molecular weight polyethylene film is 0.3mm, and the thickness of the inner EVA film is 0.5mm, and then compound with the high-pressure melt in the shaping section, the compounding temperature is 150 ℃, compounding The compression ratio of the stage is 1.2:1, and then it is cooled and formed into a product. The molding section of the mold is divided into a split section, a compression section, and a shaping section, and the heating temperature ranges are 225°C, 200°C, and 150°C. The temperature inside the cavity is controlled at 150°C, and the temperature outside the cavity is controlled at 135°C. The mechanical properties of extruded products are shown in attached table 1.

Example 3

A continuous fiber cloth/UHMWPE composite material and its double-layer co-extrusion molding process, extruded ultra-high molecular weight polyethylene sheet material, the molecular weight of the raw material is 4.5 million, first the ultra-high molecular weight polyethylene material is heated to a temperature above the melting temperature, The melt is extruded into a high-pressure melt in the compression section of the mold, and the fiber cloth is made by blending ultra-high molecular weight polyethylene fibers and carbon fibers according to the area ratio of 3:1. The surface density of the fiber cloth is 150g/m ² . Composite ultra-high molecular weight polyethylene film/EVA film, the thickness of the outer ultra-high molecular weight polyethylene film is 0.5mm, and the thickness of the inner EVA film is 0.3mm, and then compound with the high-pressure melt in the shaping section, the compounding temperature is 175°C, the compounding stage The compression ratio is 1.3:1, and then cooled and formed into products. The molding section of the mold is divided into a split section, a compression section, and a shaping section, and the heating temperature ranges are 235°C, 210°C, and 160°C. The temperature inside the cavity is controlled at 180°C, and the temperature outside the cavity is controlled at 160°C. The mechanical properties of extruded products are shown in attached table 1.

Table 1 Example 1-3 product mechanical properties

＊Note: The sliding friction coefficient test adopts reciprocating type, the test condition is pressure 5N, frequency 1Hz.

Comparative example 1

A molding process, extruding ultra-high molecular weight polyethylene profiles, the molecular weight of the raw material is 2 million, first heating the ultra-high molecular weight polyethylene material to a temperature above the melting temperature, and the melt is extruded to a high pressure in the compression section of the mold After that, the high-pressure melt is directly cooled and formed into products through the cooling section. The molding section of the mold is divided into a split section, a compression section, and a shaping section, and the heating temperature ranges are 250°C, 210°C, and 180°C.

Comparative example 2

A molding process, extruding ultra-high molecular weight polyethylene sheets, the molecular weight of the raw material is 3 million, first heating the ultra-high molecular weight polyethylene material to a temperature above the melting temperature, and the melt is extruded to a high pressure in the compression section of the mold After that, the high-pressure melt is directly cooled and formed into a product through the cooling section. The molding section of the mold is divided into a split section, a compression section, and a shaping section, and the heating temperature ranges are 235°C, 210°C, and 160°C.

Comparative example 3

A molding process, extruding ultra-high molecular weight polyethylene profiles, the molecular weight of the raw material is 2 million, first heating the ultra-high molecular weight polyethylene material to a temperature above the melting temperature, and the melt is extruded to a high pressure in the compression section of the mold Melt, the fiber cloth made by blending ultra-high molecular weight polyethylene fiber and aramid fiber according to the area ratio of 2:1, the fiber cloth surface density is 60g/m ² , the thickness of the inner EVA film on the surface is 0.2mm, and then combined with the high pressure The melt is compounded in the shaping section, the compounding temperature is 180°C, the compression ratio of the compounding section is 1.5:1, and then it is directly cooled and formed into a product through the cooling section. The molding section of the mold is divided into a split section, a compression section, and a shaping section, and the heating temperature ranges are 250°C, 210°C, and 180°C. The temperature inside the cavity is controlled at 160°C, and the temperature outside the cavity is controlled at 150°C.

Table 2 Comparative Examples 1-3 product mechanical properties

＊Note: The sliding friction coefficient test adopts reciprocating type, the test condition is pressure 5N, frequency 1Hz.

The warpage data proves from the side that the dimensional accuracy adjustment is effective. The ultra-high molecular weight polyethylene sheet and the ultra-high molecular weight polyethylene fiber are both processed with ultra-high molecular weight polyethylene resin. In the present invention, the sheet is formed by an extrusion molding process. The relevant physical parameters can refer to Table 2. UHMWPE has a high melt viscosity, poor fluidity, and poor cohesiveness. If the film is not compounded on the fiber, it is difficult to simply combine the fiber cloth and the UHMWPE matrix through co-extrusion. . The outside of the fiber cloth is not compounded with a layer of ultra-high molecular weight polyethylene film, which can be reflected in the friction coefficient will be different.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention to other forms. Any skilled person who is familiar with this profession may use the technical content disclosed above to change or remodel it into an equivalent change. Example. However, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims (10)

1. a double-layer co-extrusion molding process of continuous fiber cloth/UHMWPE composite material, it is characterized in that, the process comprises the following steps: The ultra-high molecular weight polyethylene matrix material is melt-compressed to prepare a melt parison; First, the two sides of the surface of the fiber cloth are pre-laminated with films, and then the fiber cloth and the melt parison are combined and co-extruded to form a continuous fiber cloth/UHMWPE composite material. 2. The double-layer co-extrusion molding process of a continuous fiber cloth/UHMWPE composite material according to claim 1, wherein said fiber cloth is prepared by blending ultra-high molecular weight polyethylene fiber and heat-resistant fiber Fiber cloth. 3. The double-layer co-extrusion molding process of a kind of continuous fiber cloth/UHMWPE composite material according to claim 2, characterized in that, the ratio of the area of the fiber cloth occupied by the ultra-high molecular weight polyethylene fiber and the temperature-resistant fiber (2-5):1, the surface density of the fiber cloth is 60-200g/m ² , and the blended fabric is woven in plain weave or twill weave. 4. The double-layer co-extrusion molding process of a continuous fiber cloth/UHMWPE composite material according to claim 2, wherein the temperature-resistant fiber is a fiber with a temperature resistance not lower than 200°C, including polypropylene fiber , nylon fiber, aramid fiber, carbon fiber, glass fiber, polyester fiber, viscose fiber or acrylic fiber; the ultra-high molecular weight polyethylene fiber has a strength of 25-40cN/dtex and a fineness of 50-1600D , preferably, the fiber strength is 30-35cN/dtex, and the fineness is 500-1000D. 5. The double-layer co-extrusion molding process of a continuous fiber cloth/UHMWPE composite material according to claim 1, wherein the ultra-high molecular weight polyethylene has a molecular weight of 1 million to 6 million. 6. The double-layer co-extrusion molding process of a kind of continuous fiber cloth/UHMWPE composite material according to claim 1, is characterized in that, described specific steps are: (1) Extrude the ultra-high molecular weight polyethylene base material through a single-screw extruder. In the feeding section of the screw extruder, the ultra-high molecular weight polyethylene material is heated above the melting temperature, and then the melt is transported into the mold for molding section, which is melt-compressed in the mold forming section to prepare a melt parison; (2) Pre-laminate the film on both sides of the surface of the fiber cloth, and then pass the fiber cloth through the specific cavity 1 through the pre-composite heating roller, and form a composite co-extrusion with the melt parison before the cooling section to form a continuous fiber The cloth/UHMWPE composite material is cooled and shaped through a specific cavity 2, and pulled out by a tractor. 7. The double-layer co-extrusion molding process of a continuous fiber cloth/UHMWPE composite material according to claim 6, characterized in that, in step (1), the extrusion temperature of the single screw is controlled to be 150-280 ° C and gradually increases the temperature ;In the mold forming section, there are shunt section, compression section and shaping section in sequence, and the temperature control is 250-180°C step-by-step cooling, of which the shunt section is 235-280°C, the compression section is 200-235°C, and the shaping section is 150-200°C . 8. The double-layer co-extrusion molding process of a continuous fiber cloth/UHMWPE composite material according to claim 6, characterized in that, in step (2), the specific cavity has a multi-point staged temperature control effect of internal and external measurements , The inner temperature of the cavity is controlled at 150-180°C, and the outer temperature is controlled at 135-160°C; the temperature of composite co-extrusion is 150-180°C, and the compression ratio of the composite section is (1.1-1.8):1. 9. The double-layer co-extrusion molding process of a kind of continuous fiber cloth/UHMWPE composite material according to claim 6, is characterized in that, described film comprises ultra-high molecular weight polyethylene film and EVA film, when laminating, forms Four-layer composite fiber cloth of ultra-high molecular weight polyethylene film/EVA film/fiber cloth/EVA film, UHMWPE film is located outside the cavity, with a thickness of 0.2-1mm, and the thickness of EVA film is 0.2-0.5mm. 10. A continuous fiber cloth/UHMWPE composite material prepared by the double-layer co-extrusion molding process according to any one of claims 1-9.

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