CN112172074B

CN112172074B - Glass fiber reinforced polyetherimide plate extrusion process

Info

Publication number: CN112172074B
Application number: CN202010956999.2A
Authority: CN
Inventors: 丁继平
Original assignee: Ningbo Able Precision Plastics Co ltd
Current assignee: Ningbo Able Precision Plastics Co ltd
Priority date: 2020-09-12
Filing date: 2020-09-12
Publication date: 2022-06-14
Anticipated expiration: 2040-09-12
Also published as: CN112172074A

Abstract

The invention discloses an extrusion process of a glass fiber reinforced polyetherimide plate, which relates to the field of processing of special plastics and comprises the following steps: the method comprises the following steps: pre-drying the raw materials; step two: adding raw materials into an extruder, and melting the raw materials in the extruder to form a melt; step three: cooling the melt after passing through an extrusion die to obtain a plate; wherein, extrusion tooling in step three includes mould and lower mould, go up mould and lower mould and all include reposition of redundant personnel section and preforming section, the bottom of going up mould and lower mould all is equipped with a plurality of corresponding reposition of redundant personnel pieces in reposition of redundant personnel section. Through adopting above-mentioned technical scheme, fused raw materials when flowing, it can receive the blockking of reposition of redundant personnel piece, and at this moment the raw materials can extrude to the both sides of reposition of redundant personnel piece, can take place certain mixture between the raw materials this moment to can improve the dispersibility of glass fibre in the raw materials effectively.

Description

Glass fiber reinforced polyetherimide plate extrusion process

Technical Field

The invention relates to the field of plastic extrusion, in particular to an extrusion process of a glass fiber reinforced polyetherimide plate.

Background

The cold-pushing method can produce various thermoplastic extruded plastic plates which are usually used for replacing metal to manufacture various structural members, such as gears, packing augers and the like. However, in some application scenarios, such as the propeller of an unmanned aerial vehicle, and a multi-stage compression turbine replacing titanium alloy, i.e., the specific modulus, strength and rigidity of the pure resin plate are far from the use requirements, it is necessary to reinforce the pure resin material, and the mechanical properties of the material reinforced by fillers such as glass fiber, carbon fiber and the like are greatly improved, so that the application range is expanded. As shown in table 1, we can see the comparison of the performance of pure PEI versus 30% glass fiber reinforced PEI.

TABLE 1

Meanwhile, a new problem occurs, namely, due to the fact that the specific gravity of the glass fiber is larger than that of the PEI (the specific gravity of the glass fiber is 2.4-2.76 g/cm in the following year, the specific gravity of the PEI is 1.27g/cm in the following year), the flowability of the glass fiber is poor, and therefore when the 30% glass fiber reinforced PEI is used for extruding the plate, the dispersion of the glass fiber in the plate is prone to be uneven, and the unevenness is mainly expressed in two aspects:

1. because the melted materials are subjected to the longitudinal conveying force of the screw rod during extrusion, the glass fibers are arranged in a II shape;

2. the glass fiber is settled and agglomerated when the large-thickness plate is produced because the specific gravity of the glass fiber is greater than that of PEI.

The phenomenon of uneven dispersion of glass fibers also exists in other reinforced plastics, but the problem is very intuitive to show on a PEI plate because PEI is an amorphous semitransparent plastic and the situation of uneven dispersion of the glass fibers can be clearly seen when a 2mm thin sheet is cut and bright light is applied to the back of the PEI plate.

Due to the phenomenon of uneven dispersion of glass fibers in the board, the performance of each part of the board is not uniform, anisotropy is shown, and the product quality is seriously influenced.

Therefore, it is necessary to design a new process to ensure the uniform dispersion of the glass fiber in the polyetherimide sheet.

Disclosure of Invention

The invention aims to provide an extrusion process of a glass fiber reinforced polyetherimide plate, which can effectively improve the dispersion degree of glass fibers in polyetherimide and finally ensure the isotropy of the plate.

The above purpose of the invention is realized by the following technical scheme: the glass fiber reinforced polyetherimide plate extrusion process comprises the following steps:

the method comprises the following steps: pre-drying the raw materials;

step two: adding raw materials into an extruder, and melting the raw materials in the extruder to form a melt;

step three: cooling the melt after passing through an extrusion die to obtain a plate;

wherein, extrusion tooling in step three includes mould and lower mould, go up mould and lower mould and all include reposition of redundant personnel section and preforming section, the bottom of going up mould and lower mould all is equipped with a plurality of corresponding reposition of redundant personnel pieces in reposition of redundant personnel section.

Through adopting above-mentioned technical scheme, the fuse-element is when flowing, and it can receive blocking of reposition of redundant personnel piece, and at this moment the raw materials can extrude to the both sides of reposition of redundant personnel piece, can take place certain mixture between the raw materials this moment to can improve the dispersibility of glass fibre in the panel effectively.

Preferably, the shunting block is a triangular pyramid.

By adopting the technical scheme, the melt can roll when flowing through the triangular pyramid. At the moment, the glass fibers which are longitudinally arranged are interfered by the triangular pyramid, so that the glass fibers which are originally parallel to the flowing direction of the raw materials and flow along with the melt can be W-shaped, the dispersion degree of the glass fibers in the plate is improved, and the multi-directionality of the glass fibers is realized.

Preferably, one edge of the shunting block, which is located on a vertical plane, is the same as the flow direction of the raw material when the raw material enters the extrusion die.

By adopting the scheme, the melt can be directly cut by the edges of the shunting blocks in the moving process, so that the melt can flow along the surfaces of the shunting blocks easily under the condition of ensuring the mutual mixing of the melt, and the resistance of the melt in the flowing process is reduced.

Preferably, the side edge of the shunting block, which is contacted with the bottom of the upper die or the lower die, is parallel to the side wall of the shunting section of the upper die and the side wall of the shunting section of the lower die respectively.

By adopting the technical scheme, the melt can be ensured to smoothly flow between the shunting block and the side wall of the upper die or the lower die under the condition that the shunting block is ensured to promote the melt to be mixed, so that the possibility that the melt is detained in the die is reduced.

Preferably, the upper die or the lower die is provided with four shunting blocks, three shunting blocks on the upper die or the lower die are arranged at equal intervals along the width direction of the extrusion die, and the other shunting block is positioned between the inlet of the extrusion die and the three shunting blocks and on the middle line of the three shunting blocks.

Through adopting above-mentioned technical scheme, on the one hand the raw materials can evenly spread out in whole mould like this for panel can be more level and smooth after extruding, and on the other hand can realize multistage compulsory reposition of redundant personnel, is favorable to improving the dispersion degree of glass fibre in the fuse-element, thereby has guaranteed the uniformity of the whole mechanical properties of panel.

Preferably, the upper die and the lower die are coated with coatings, and the friction coefficient of the coatings is 0.3-0.5.

Through adopting above-mentioned technical scheme, like this at the melt flow in-process, can reduce the frictional force between raw materials and the mould to also be favorable to improving the mixedness of raw materials.

Preferably, in the step one, the raw materials are pre-dried for more than 4 hours at 150 ℃.

By adopting the technical scheme, the raw material is pre-dried for 4 hours at the temperature of 150 ℃, so that the moisture in the raw material can be effectively removed, and the moisture on the surface of the raw material can be reduced from evaporating and generating bubbles, thereby influencing the processing of the raw material in a mold.

In conclusion, the beneficial technical effects of the invention are as follows:

1. the upper die and the lower die of the die are provided with the shunting blocks, so that the melt can be shunted towards the two sides of the shunting blocks after being blocked by the shunting blocks, and uniform dispersion between the glass fibers and the melt is favorably realized;

2. the shunting block is a triangular pyramid, so that when the glass fibers pass through the shunting block, the glass fibers can move over the shunting block, and the glass fibers which are originally parallel to the flow direction of the melt can be changed into W-shaped glass fibers, so that the dispersibility of the glass fibers is ensured, and the performances of the final plate in different directions and different positions are kept consistent.

Drawings

FIG. 1 is a schematic view of an extrusion die;

FIG. 2 is a top view of an extrusion die;

FIG. 3 is an electron micrograph of sample 1;

fig. 4 is an electron micrograph of comparative sample 1.

In the figure, 1, an upper die; 2. a lower die; 21. a flow splitting section; 22. a preforming section; 23. a shunting block; 3a, a bolt; 3b, a nut.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

The glass fiber reinforced polyetherimide plate extrusion process comprises the following steps:

the method comprises the following steps: pre-drying polyetherimide at 150 ℃ for 4 hours;

step two: mixing the dried polyetherimide and the glass fiber, adding the mixture into an extruder, and melting to form a melt;

step three: and the melt passes through an extrusion die of the machine head under the pushing action of the extruder, and is cooled to obtain the required plate.

Here, as shown in fig. 1, the extrusion die mainly includes an upper die 1 and a lower die 2, and the upper die 1 and the lower die 2 are fixed by a bolt 3a and a nut 3 b. The upper die 1 and the lower die 2 are divided into a diverging section 21 and a preforming section 22. Wherein, the flow dividing section 21 gradually expands from the inlet to the outlet of the extrusion die to form a trapezoidal structure. And the pre-forming section 22 is located on the side of the diverging section 21 near the exit of the extrusion die and is rectangular. Here, the preformed section and the flow dividing section 21 are connected and flush on the side facing the outlet of the extrusion die.

Furthermore, as shown in fig. 1 and fig. 2, the upper die 1 and the lower die 2 are both provided with a plurality of shunting blocks 23, and the number of the shunting blocks 23 can be determined according to actual conditions. Here, the number of the shunting blocks 23 in the upper die 1 and the lower die 2 is 4, and the shunting blocks 23 in the upper die 1 and the lower die 2 are arranged in a one-to-one correspondence. The shape of the shunting block 23 can be adjusted according to the requirement, so that the glass fibers can be better and uniformly dispersed in the plate, wherein the shunting block 23 is in a triangular pyramid shape.

And, three of the diverter blocks 23 on the upper die 1 or the lower die 2 are arranged at equal intervals along the width direction of the extrusion die, one of the three diverter blocks 23 is flush with the side of the diverter segment 21 close to the outlet side of the extrusion die, and the other diverter block 23 is located between the inlet of the extrusion die and the three diverter blocks 23 and on the middle line of the three diverter blocks 23. At the same time, one apex angle of the one diverter block 23 is flush with the inlet edge of the extrusion die. Thus, the edge of one of the four diverter blocks 23 that lies in the vertical plane is in the same direction as the melt flows as it enters the extrusion die. Therefore, the melt can be directly divided by the edges of the shunting blocks 23, so that the melt can flow along the surfaces of the shunting blocks 23 easily under the condition of ensuring the intermixing of the melt, and the resistance in the flowing process is reduced. Also, the melt may tumble as it passes through diverter block 23. At this time, the glass fibers arranged longitudinally are interfered by the triangular pyramid, so that the glass fibers originally parallel to the flowing direction of the raw materials and flowing along with the raw materials are W-shaped, and the dispersion degree of the glass fibers in the plate is improved.

In addition, in order to improve the flow of the melt in the die, the upper die 1 and the lower die 2 are coated with fluorocarbon coatings, the fluorocarbon coatings can be selected from DuPont Teflon 958G-303, and the friction coefficient of the coatings is 0.3-0.5. And, when the flow is carried out in the melt mould, the mechanical energy loss of the melt can be effectively reduced.

The polyetherimide containing 30wt% glass fiber was fed to the extruder with the extrusion die of the present application, and then a 10cm by 10cm sample of the sheet material was randomly taken every 10min at the extrusion die exit, for a total of 5 times, and numbered sample a1, sample a2, sample A3, sample a4, and sample a5, respectively. Thereafter, the cross section of sample a1 was subjected to electron microscopy to obtain an electron micrograph as shown in fig. 3. Meanwhile, the 5 samples are tested for tensile strength, tensile elastic modulus, bending strength and bending elastic modulus, and the specific test results are shown in the following table 2:

TABLE 2

Item	Glass fiber not added	Sample A1	Sample A2	Sample A3	Sample A4	Sample A5
							Tensile strength Mpa	105	161	158	159	162	160
Modulus of elasticity in tension Gpa	3.0	9.2	9.1	9.0	9.0	8.9
							Flexural strength Mpa	145	230	231	229	228	231
Flexural modulus of elasticity Gpa	3.3	9.1	9.0	9.1	8.9	9.2

Further, a polyetherimide containing 30wt% of glass fiber was fed to an extruder equipped with an extrusion die having a flow-dividing block of an oval shape, and then a 10cm by 10cm sample of a plate material was taken at the extrusion die outlet every 10min, and the samples were taken 5 times in total, and respectively numbered as comparative sample B1, comparative sample B2, comparative sample B3, comparative sample B4, and comparative sample B5. Then, the cross section of comparative sample B1 was subjected to electron microscopy to obtain an electron micrograph as shown in fig. 4. The 5 comparative samples were tested for tensile strength, tensile modulus, flexural strength and flexural modulus, and the specific test results are shown in table 3 below:

TABLE 3

Item	Comparative sample B1	Comparative sample B2	Comparative sample B3	Comparative sample B4	Comparative sample B5
						Tensile strength Mpa	130	137	173	120	168
Modulus of elasticity in tension Gpa	5.2	6.0	9.8	4.9	9.4
						Flexural strength Mpa	186	201	241	172	236
Flexural modulus of elasticity Gpa	5.9	6.1	9.8	4.8	9.5

As can be seen from the comparison between the attached drawings 3 and 4, the glass fibers in the plate extruded by the extruder with the extrusion die are more multidirectional and more uniform in distribution. And the test results in tables 2 and 3 show that when the glass fibers are in a multi-directional state and are uniformly distributed, the mechanical property strength of the plate can be improved, and meanwhile, the isotropy of the overall performance of the plate can be ensured.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

Claims

1. The glass fiber reinforced polyetherimide plate extrusion process is characterized by comprising the following steps: comprises the following steps of (a) carrying out,

the method comprises the following steps: pre-drying the raw materials;

the extrusion die in the third step comprises an upper die (1) and a lower die (2), wherein the upper die (1) and the lower die (2) both comprise a shunting section (21) and a preforming section (22), and a plurality of corresponding shunting blocks (23) are arranged at the bottom of the upper die (1) and the bottom of the lower die (2) in the shunting section (21);

the flow splitting block (23) is a triangular pyramid, and one edge of the flow splitting block (23) located on a vertical plane is the same as the flow direction of raw materials when the raw materials enter the extrusion die.

2. The glass fiber reinforced polyetherimide sheet extrusion process of claim 1, wherein: the side edge of the shunting block (23) which is contacted with the bottom of the upper die (1) or the lower die (2) is respectively parallel to the side walls of the shunting sections (21) of the upper die (1) and the lower die (2).

3. The glass fiber reinforced polyetherimide sheet extrusion process of claim 2, wherein: the upper die (1) or the lower die (2) is provided with four shunting blocks (23), three shunting blocks (23) on the upper die (1) or the lower die (2) are arranged at equal intervals along the width direction of the extrusion die, and the other shunting block (23) is positioned between the inlet of the extrusion die and the three shunting blocks (23) and is positioned on the middle line of the three shunting blocks (23).

4. The extrusion process of the glass fiber reinforced polyetherimide sheet material as claimed in claim 1, wherein the extrusion process comprises the following steps: the upper die (1) and the lower die (2) are internally coated with coatings, and the friction coefficient of the coatings is 0.3-0.5.

5. The glass fiber reinforced polyetherimide sheet extrusion process of claim 1, wherein; in the first step, the raw materials are pre-dried for more than 4 hours at the temperature of 150 ℃.