WO2018090314A1 - Long fiber ultra-short thermoplastic forming process - Google Patents

Abstract

A long fiber ultra-short thermoplastic forming process. In the process, molten modified polypropylene and separated glass fibers are mixed and cut off quantitatively, and then directly fed into a thermostatic plunger injection machine, thereby preventing the blank material from being exposed to air and oxidized which would cause a skin to be formed on the surface thereof; and then the blank material is fed into the mold cavity of a press machine to be subjected to a rapid compression molding for a compression molding time less than 1.0 second, shortening the compression molding time, saving robotic or manual grabbing time, while reducing requirements on the power of the press machine, lowering the production cost.

Description

Long fiber ultra-short process thermoplastic molding process Technical field

The invention belongs to the technical field of composite materials, and in particular relates to a long fiber ultra-short process thermoplastic molding process.

Background technique

Long fiber reinforced thermoplastic (LFT) is a kind of thermoplastic composite material, and it is also a hot spot for the development of foreign thermoplastic composite materials. The material is lightweight, high-strength, environmentally-friendly and recyclable. It is widely used in the automotive industry, such as structural and semi-structural components such as front-end modules, bumper beams, instrument clusters, battery trays, spare tire compartments, The seat frame, pedals and integral floor are ideal for lightweight vehicles. The LFT-D production line is a long-fiber reinforced thermoplastic online compounding production line. It is a direct molding of fiber and thermoplastic resin directly into a product. The production line is mainly composed of three parts, namely extrusion and handling (robot). Molding (press). The extrusion part is mainly for plasticizing and compounding the resin, resin and fiber are combined, and the composite material block is output; the main body of the press adopts an integral frame structure, and the front and rear main frames are each cut by a single piece of steel plate by wire cutting. The structure has good rigidity and high precision, and the safety protection device such as safety protection grating and laser scanner is provided before and after the pressing machine.

LFT-D molding technology is a new long fiber reinforced thermoplastic composite process technology after GMT and LFT-G. The key factor distinguishing it from GMT and LFT-G is that the semi-finished product step is omitted, in the material selection. More flexible, it is the new molding technology that has attracted the most attention and the fastest growing market in the automotive composites industry in recent years. In the LFT-D technology, not only the fiber content and the length of the fiber can be directly adjusted to the requirements of the final part, but the matrix polymer can also be directly adjusted to the requirements of the final part. The mechanical and special application properties of the article, such as thermal stability, colorability, UV stability, and fiber-to-substrate bonding characteristics, can be altered and influenced by the use of different additives.

However, in the LFT-D molding process, the extruded billet is easily exposed to air crusts, and the press has a longer molding time. Therefore, it is necessary to improve the molding process of the LFT-D.

Summary of the invention

The object of the present invention is to provide a long fiber ultra-short process thermoplastic molding process in view of the deficiencies of the prior art.

The invention is achieved by the following technical solutions:

A long fiber ultra-short process thermoplastic molding process comprising the following steps:

S1, mixing polypropylene and auxiliary reagent to obtain modified polypropylene;

S2, the modified polypropylene is added to a vacuum feeder, and then sent to a continuous weighing and metering mixing device for weighing, and then melted and extruded into a screw extruder;

S3. The glass fiber is detected by a glass fiber detecting and breaking device, and then the qualified product is heated and dried;

S4, using a metering and cutting device to perform fiber separation processing on the S3 product;

S5, the S2 product is sent together with the S4 product into a twin-screw extruder to be kneaded to form a continuous block, and then quantitatively cut off;

S6, the S5 product is directly sent to the thermostatic plunger type injection machine, and the blank is directly sent to the mold cavity of the press through the constant temperature plunger type injection machine;

S7, using a press to rapidly mold the blank, the molding time is less than 1.0 second, and demoulding after molding and curing;

S8. The S7 product is post-processed, and then the quality inspection is performed, and the qualified products are packed and put into the warehouse.

Preferably, the auxiliary agent is one or more of a coupling agent, an initiator, a catalyst, an antioxidant, a compatibilizer, and a lubricant.

Preferably, the mass fraction of the glass fibers in the S5 product is 30-40%, and the mass fraction of the modified polypropylene is 60-70%.

Preferably, the rotational speed of the screw extruder in S5 is 130-180 rpm/min.

Preferably, the length of the glass fiber after cutting is 10-50 mm.

Preferably, the kneading temperature in the S5 is from 200 to 250 °C.

Preferably, the temperature in said S6 is from 160 to 175 °C.

Preferably, the molding pressure in the S7 is from 1200 to 1350T.

Preferably, the post-treatment in S8 is deburring, deburring, and punching.

The beneficial effects of the invention are:

(1) The long fiber ultra-short process thermoplastic molding process of the present invention, the blank is mixed by a twin-screw extruder After being dispensed, it is directly sent to a constant temperature plunger type injection machine, so as to prevent the blank from being exposed to air and being oxidized to make the surface crust;

(2) The long fiber ultra-short process thermoplastic molding process of the invention shortens the process flow, improves the fluidity and mechanical properties of the blank, thereby improving the appearance quality of the product;

(3) The long fiber ultra-short process thermoplastic molding process of the invention, the molding time of the press is less than 1.0 second, the molding time is greatly shortened, the robot (or manual) grasping time is saved, and the power requirement of the press is reduced. , reducing production costs.

DRAWINGS

In order to more clearly illustrate the technical solutions of the present invention, the drawings used in the embodiments or the prior art description will be briefly described below. It is obvious that the drawings in the following description are merely embodiments of the present invention. Other drawings may also be obtained from those of ordinary skill in the art in light of the inventive work.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart of a long fiber ultra-short process thermoplastic molding process of the present invention.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the accompanying drawings. It is obvious that the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

Example 1:

Please refer to Figure 1. As shown, the present invention discloses a long fiber ultra-short process thermoplastic molding process comprising the following steps:

S1, a polypropylene having a mass fraction of 99%, a coupling agent of 0.8%, and an initiator of 0.2% are mixed to obtain a modified polypropylene;

S2, the modified polypropylene is added to a vacuum feeder, and then sent to a continuous weighing and metering mixing device for weighing, and then melted and extruded into a screw extruder;

S3, using a glass fiber detecting and breaking device to detect the glass fiber, removing the broken glass fiber, and then heating and drying the qualified product;

S4, using a metering and cutting device to perform fiberizing treatment on the S3 product, the length of the glass fiber after cutting Degree is 10mm;

S5, the S2 product with a mass fraction of 70% is sent to the twin-screw extruder together with the S4 product with a mass fraction of 30% to be kneaded to form a continuous block, and the rotation speed of the screw extruder is 130 rpm/min. The mixing temperature is 250 ° C, and then quantitatively cut off;

S6, the S5 product is directly sent to the thermostatic plunger type injection machine, and the billet is directly sent to the mold cavity of the press through the constant temperature plunger type injection machine, and the temperature is controlled to be 160 ° C, thereby preventing the billet from being exposed to the air and being oxidized. Its surface is crusted;

S7, using a press to rapidly mold the blank, the molding pressure is 1200T, the molding time is 0.8 seconds, and the mold is demoulded and molded to release the mold;

S8, the S7 product is deburred, deburred and punched, and then quality inspection is carried out, and the qualified products are packed into the warehouse.

Example 2:

Please refer to Figure 1. As shown, the present invention discloses a long fiber ultra-short process thermoplastic molding process comprising the following steps:

S1, a polypropylene having a mass fraction of 99% and a 1% antioxidant are mixed to obtain a modified polypropylene;

S2, the modified polypropylene is added to a vacuum feeder, and then sent to a continuous weighing and metering mixing device for weighing, and then melted and extruded into a screw extruder;

S3, using a glass fiber detecting and breaking device to detect the glass fiber, removing the broken glass fiber, and then heating and drying the qualified product;

S4, using a metering and cutting device to perform fiberizing treatment on the S3 product, the length of the glass fiber after cutting is 50 mm;

S5, the S2 product having a mass fraction of 60% is sent to the twin-screw extruder together with the S4 product having a mass fraction of 40% to be kneaded to form a continuous block, and the rotation speed of the screw extruder is 180 rpm/min. The mixing temperature is 200 ° C, and then quantitatively cut off;

S6, the S5 product is directly sent to the thermostatic plunger type injection machine, and the billet is directly sent into the mold cavity of the press through the constant temperature plunger type injection machine, and the temperature is controlled to be 175 ° C, thereby preventing the billet from being exposed to the air and being oxidized. Its surface is crusted;

S7, using a press to rapidly mold the blank, the molding pressure is 1350T, the molding time is 0.5 seconds, and the mold is demoulded and molded to release the mold;

S8, the S7 product is deburred, deburred and punched, and then quality inspection is carried out, and the qualified products are packed into the warehouse.

Example 3:

Please refer to Figure 1. As shown, the present invention discloses a long fiber ultra-short process thermoplastic molding process comprising the following steps:

S1, a polypropylene having a mass fraction of 98%, a 1.3% lubricant, and a 0.7% compatibilizer are mixed to obtain a modified polypropylene;

S2, the modified polypropylene is added to a vacuum feeder, and then sent to a continuous weighing and metering mixing device for weighing, and then melted and extruded into a screw extruder;

S3, using a glass fiber detecting and breaking device to detect the glass fiber, removing the broken glass fiber, and then heating and drying the qualified product;

S4, using a metering and cutting device to perform fiberizing treatment on the S3 product, the length of the glass fiber after cutting is 20 mm;

S5, the S2 product with a mass fraction of 65% is sent to the twin-screw extruder together with the S4 product with a mass fraction of 35% to be kneaded to form a continuous block, and the rotation speed of the screw extruder is 150 rpm/min. The mixing temperature is 220 ° C, and then quantitatively cut off;

S6, the S5 product is directly sent to the thermostatic plunger type injection machine, and the billet is directly sent into the mold cavity of the press through the constant temperature plunger type injection machine, and the temperature is controlled to 170 ° C, thereby preventing the billet from being exposed to the air and being oxidized. Its surface is crusted;

S7, using a press to rapidly mold the blank, the molding pressure is 1300T, the molding time is 0.7 seconds, and the mold is demoulded and molded to release the mold;

S8, the S7 product is deburred, deburred and punched, and then quality inspection is carried out, and the qualified products are packed into the warehouse.

The beneficial effects of the invention are:

(1) The long fiber ultra-short process thermoplastic molding process of the present invention, after the billet is mixed by a twin-screw extruder, directly sent to a thermostatic plunger type injection machine, thereby preventing the billet from being exposed to air and being oxidized to a surface thereof. Crust

(2) The long fiber ultra-short process thermoplastic molding process of the invention shortens the process flow, improves the fluidity and mechanical properties of the blank, thereby improving the appearance quality of the product;

(3) The long fiber ultra-short process thermoplastic molding process of the invention, the molding time of the press is less than 1.0 second, the molding time is greatly shortened, the robot (or manual) grasping time is saved, and the power requirement of the press is reduced. , reducing production costs.

The above is a preferred embodiment of the present invention, and it should be noted that those skilled in the art can also make several improvements and retouchings without departing from the principles of the present invention. These improvements and retouchings are also considered. It is the scope of protection of the present invention.

Claims (9)

A long fiber ultra-short process thermoplastic molding process characterized by comprising the following steps: S1, mixing polypropylene and auxiliary reagent to obtain modified polypropylene; S2, the modified polypropylene is added to a vacuum feeder, and then sent to a continuous weighing and metering mixing device for weighing, and then melted and extruded into a screw extruder; S3. The glass fiber is detected by a glass fiber detecting and breaking device, and then the qualified product is heated and dried; S4, using a metering and cutting device to perform fiber separation processing on the S3 product; S5, the S2 product is sent together with the S4 product into a twin-screw extruder to be kneaded to form a continuous block, and then quantitatively cut off; S6, the S5 product is directly sent to the thermostatic plunger type injection machine, and the blank is directly sent to the mold cavity of the press through the constant temperature plunger type injection machine; S7, using a press to rapidly mold the blank, the molding time is less than 1.0 second, and demoulding after molding and curing; S8. The S7 product is post-processed, and then the quality inspection is performed, and the qualified products are packed and put into the warehouse. A long fiber ultrashort process thermoplastic molding process according to claim 1, wherein the auxiliary agent is one or more of a coupling agent, an initiator, a catalyst, an antioxidant, a compatibilizer, and a lubricant. The long fiber ultra-short process thermoplastic molding process according to claim 1 or 2, wherein the mass fraction of the glass fibers in the S5 product is 30-40%, and the mass fraction of the modified polypropylene is 60-70%. A long fiber ultrashort process thermoplastic molding process according to claim 3, wherein the S5 screw extruder has a rotational speed of 130-180 rpm/min. A long fiber ultra-short flow thermoplastic molding process according to claim 4, wherein the glass fiber has a length of 10 to 50 mm after cutting. A long fiber ultrashort process thermoplastic molding process according to claim 1 or 5, wherein the kneading temperature in said S5 is from 200 to 250 °C. A long fiber ultrashort process thermoplastic molding process according to claim 1, wherein the temperature in said S6 is from 160 to 175 °C. A long fiber ultra-short process thermoplastic molding process according to claim 1, wherein the molding pressure in said S7 is from 1,200 to 1,350 T. A long fiber ultrashort process thermoplastic molding process according to claim 8, wherein the post treatment in S8 is deburring, deburring, and punching.

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