CN115141461A

CN115141461A - SMC material and preparation process thereof

Info

Publication number: CN115141461A
Application number: CN202210872095.0A
Authority: CN
Inventors: 陈勇; 吴辉; 胡丽娟; 孙平
Original assignee: Hefei Royalstar Electronic Appliance Group Co Ltd
Current assignee: Hefei Royalstar Electronic Appliance Group Co Ltd
Priority date: 2022-07-22
Filing date: 2022-07-22
Publication date: 2022-10-04
Anticipated expiration: 2042-07-22
Also published as: CN115141461B

Abstract

The invention belongs to the technical field of resin materials, and particularly relates to an SMC material which comprises a first component and a second component, wherein the first component accounts for 35-60 percent by taking the total weight of the first component and the second component as 100 percent; wherein the first component is glass fiber, and the length of the glass fiber is 10-60mm; the second component comprises, by weight, 100 parts of matrix resin, 2-5 parts of graphene, 12-25 parts of elastomer low-shrinkage additive, 120-180 parts of inorganic filler, 15-20 parts of curing agent, 1-3 parts of internal mold release agent, 2-30 parts of color paste, 1-5 parts of process additive and 1-8 parts of thickening agent; also provides a preparation process of the SMC material. The invention not only enhances the strength of the SMC material, but also enhances the toughness, the shock resistance and the fracture capability of the SMC material; the using amount of the inorganic filler is increased, the production cost is saved, and the overall performance of the material is enhanced, so that the material is suitable for various scenes, and the application range of the material is expanded.

Description

SMC material and preparation process thereof

Technical Field

The invention belongs to the technical field of resin materials, and particularly relates to an SMC material and a preparation process thereof.

Background

SMC (Sheet molding compound) is a Sheet molding compound, generally is subjected to high-temperature one-step compression molding, has the advantages of high mechanical strength, light material weight, corrosion resistance, long service life, high insulating strength, electric arc resistance, flame retardance, good sealing performance and the like, has incomparable advantages with other non-metallic materials and metallic materials, is flexible in product design and easy for large-scale production, and is widely applied to the industries of electricity, electronics, vehicles, buildings, chemical engineering, aviation and the like.

In the SMC material, the shrinkage of the resin during the processing and molding process is generally reduced by adding a Low Profile Additive (LPA) to prevent the occurrence of cracks in the resin phase, improve the quality defects of the resin surface, and avoid the problems of dimensional runaway and the like. The low shrinkage additive as an important key raw material in the production process of SMC materials can be roughly divided into two types according to the difference of molecular structures and properties: the plastic LPA and the elastomer LPA, which are currently the most commonly used plastic LPA, include non-polar plastic LPA (polystyrene) and polar plastic LPA (polyvinyl acetate), although both can effectively reduce the shrinkage rate of the resin, the non-polar plastic LPA has poor compatibility with the resin, and is a two-phase system with the resin before the resin is cured, so the requirements on the type and the dosage of the curing agent are severe, and the polar plastic LPA is well compatible with the resin, but has poor mechanical strength; elastomer LPAs are used less often, which can enhance the toughness and fracture ability of SMC materials, and are also used gradually in more scenes, but elastomer LPAs reduce the mechanical strength of the materials to some extent.

In SMC materials, glass fiber is most commonly used to enhance the strength, but the content of glass fiber in the common SMC materials on the market is not higher than 30% (for example, patent CN 107556721A). However, with the development of economic technology, SMC materials are used in more fields, and in some fields, higher requirements are put on the performance of SMC materials, namely, the mechanical strength, temperature resistance and dimensional stability are required to be equivalent to or even higher than those of metal materials, which requires the improvement and optimization of the existing SMC materials, so that the new generation of SMC materials with high fiber content and high performance matrix resin is started to be applied to meet the market demand. Increasing the glass fiber content and increasing the length, as one would expect, can enhance the mechanical strength of the SMC material, but this does not mean that the highest mechanical strength product can be obtained using the highest fiber content and longest fiber length SMC material, since long fibers do not have good flowability and limit their development, so the high properties of the material itself do not always translate into good moulded products.

Therefore, in view of the above analysis, the present invention creatively adds elastomer LPA to SMC material to improve the flow property of the system, and adds a larger amount of longer glass fiber to match the reinforcing effect of graphene to improve the problem of mechanical strength reduction caused by elastomer LPA, and determines the optimum addition amount of each component through research to finally obtain SMC material with enhanced performance.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide an SMC material which has high strength, good toughness, high hardness, low cost and easy preparation. In order to realize the purpose of the invention, the following technical scheme is adopted:

an SMC material comprising a first component and a second component, the first component comprising from 35% to 60% by weight, based on 100% by weight of the first component and the second component;

wherein the first component is glass fiber, and the length of the glass fiber is 10-60mm;

wherein the second component comprises the following components in parts by weight: 100 parts of matrix resin, 2-5 parts of graphene, 12-25 parts of elastomer low-shrinkage additive, 120-180 parts of inorganic filler, 15-20 parts of curing agent, 1-3 parts of internal release agent, 2-30 parts of color paste, 1-5 parts of process additive and 1-8 parts of thickening agent.

Preferably, the matrix resin is one of epoxy resin, vinyl ester resin or polyimide resin.

Preferably, the elastomeric low profile additive is a polyurethane.

Preferably, the inorganic filler is one of aluminum hydroxide or calcium carbonate, and the particle size of the inorganic filler is 50 to 100 meshes.

Preferably, the curing agent is one of tert-butyl peroxybenzoate or dicumyl peroxide; the internal release agent is one of calcium stearate or zinc stearate; the process auxiliary agent is one of process auxiliary agent BYK-W996 or process auxiliary agent BYK-W9010; the thickening agent is one of magnesium oxide, magnesium hydroxide or calcium hydroxide.

Preferably, the color paste is prepared by mixing and developing a toner and a matrix resin, and the content of the toner in the color paste is 5-20wt%.

In order to achieve the above object, the present invention further provides a process for preparing the SMC material, which comprises the following steps:

(1) Weighing the first component according to the formula, and cutting the glass fiber to a corresponding length by a cutter for later use; weighing each component of the second component according to the formula, and drying the solid at 40-50 deg.C for 3-5 min;

(2) Dispersing graphene in the second component in an organic solution, and performing ultrasonic dispersion to obtain a graphene premix;

(3) Adding matrix resin into the graphene premixed liquid obtained in the step (2), stirring for 10-20min at the rotating speed of 1200-1500r/min to mix, then adding the elastomer low-shrinkage additive, the curing agent, the internal release agent, the color paste and the process aid, mixing and stirring for 5-10min, then adding the inorganic filler, continuing stirring for 10-15min, finally adding the thickening agent, adjusting the stirring speed to be 100-500r/min, and stirring until the system temperature is below 45 ℃ to obtain resin paste;

(4) Respectively and uniformly coating a layer of resin paste obtained in the step (3) on two polyethylene films, uniformly dispersing the glass fibers prepared in the step (1) on the resin paste of one polyethylene film, coating at least one layer of resin paste on the surface of the polyethylene film in which the glass fibers are dispersed, covering the polyethylene film with the other polyethylene film coated with the resin paste, scraping the outer surface of the polyethylene film by using a scraper to discharge bubbles, and completely soaking the glass fibers in the resin paste to prepare an SMC sheet;

(5) And (5) carrying out die pressing and rolling on the SMC sheet material obtained in the step (4) to obtain a sheet molding compound, and then moving the sheet molding compound into a drying room for curing to obtain the SMC material.

Preferably, the organic solution in step (2) is one of styrene, ethylene glycol or methyl methacrylate.

Preferably, the content of graphene in the graphene premix in the step (2) is 0.5-5wt%.

Preferably, the temperature of the press mold in the step (5) is 140 to 150 ℃, the pressure of the press mold is 5 to 20MPa, and the time per millimeter thickness of the press mold is 4 to 60s.

Compared with the prior art, the invention has the beneficial effects that: the elastomer low-shrinkage additive is added, so that the curing shrinkage can be reduced, the surface of the SMC material is optimized, the toughness, the impact resistance and the fracture resistance of the SMC material are enhanced, and the coloring condition of the SMC material is improved; in addition, the elastomer low-shrinkage additive can also increase the flow property of a system so as to increase the addition amount of inorganic filler and glass fiber, thereby reducing the production cost, adopting the glass fiber with longer length, enhancing the strength of the SMC material, and further enhancing the strength of the SMC material by matching with the addition of graphene so as to make up the problem of mechanical strength reduction caused by the elastomer low-shrinkage additive, thereby obtaining the SMC material with enhanced performance.

Drawings

FIG. 1 is a schematic flow chart of a process for preparing an SMC material.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Detailed description of the preferred embodiment 1

The SMC material in this example includes a first component and a second component, wherein the first component comprises 35%, based on 100% total weight of the first and second components, and is 10mm long glass fibers; the second component specifically comprises the following components in parts by weight:

matrix resin	100 portions of
		Graphene	2 portions of
Elastomer low profile additives	12 portions of
		Inorganic filler	120 portions of
Curing agent	15 portions of
		Internal mold release agent	1 part of
Color paste	2 portions of
		Process aid	1 part of
Thickening agent	1 part of

Wherein the matrix resin is epoxy resin; the elastomer low-shrinkage additive is polyurethane; the inorganic filler is aluminum hydroxide, and the granularity of the inorganic filler is 50 meshes; the curing agent is tert-butyl peroxybenzoate; the internal release agent is calcium stearate; the process auxiliary agent is a process auxiliary agent BYK-W996; the thickener is magnesium oxide.

Wherein the color paste is prepared by mixing and developing a toner and matrix resin, and the content of the toner in the color paste is 5wt%.

Fig. 1 is a schematic flow chart of a preparation process of an SMC material of the present invention, and it can be seen that the preparation process of the SMC material of the present invention includes the following steps:

step S1: weighing the first component according to the formula, and cutting the glass fiber to 10mm by a cutter for later use; weighing each component of the second component according to the formula, and drying the solid at 40 deg.C for 5min for use.

Step S2: and dispersing graphene in the second component in styrene, and performing ultrasonic dispersion for 0.5h under the ultrasonic power of 500W to obtain a graphene premix, wherein the content of the graphene is 0.5wt%.

And step S3: and (3) adding matrix resin into the graphene premixed liquid obtained in the step (S2), stirring for 10min at the rotating speed of 1200r/min to mix, then adding the elastomer low-shrinkage additive, the curing agent, the internal release agent, the color paste and the process auxiliary agent, mixing and stirring for 5min, then adding the inorganic filler, continuously stirring for 10min, finally adding the thickening agent, adjusting the stirring speed to be 100r/min, and stirring until the system temperature reaches 42 ℃ to obtain the resin paste.

And step S4: the two polyethylene films are respectively and uniformly coated with a layer of resin paste obtained in step S3, the glass fibers prepared in step S1 are uniformly dispersed on the resin paste of one of the polyethylene films, and according to practical conditions, the surface of the polyethylene film on which the glass fibers are dispersed is coated with a layer of resin paste (to control the thickness of the SMC material), and then the other polyethylene film (with the side coated with the resin paste) is used for covering, so that the glass fibers are dispersed between the resin pastes on the two polyethylene films, and the outer surface of the polyethylene film is scraped with a scraper to discharge air bubbles, and so that the glass fibers are completely impregnated in the resin paste, thus obtaining an SMC sheet.

Step S5: and (5) performing die pressing and rolling on the SMC sheet obtained in the step (S4) to obtain a sheet molding compound, and then moving the sheet molding compound into a drying room for curing to obtain the SMC material, wherein in the step, the temperature of the die pressing is 140 ℃, the pressure is 5MPa, and the time of the die pressing per millimeter is 4S.

Specific example 2

The SMC material in this example includes a first component and a second component, wherein the first component comprises 60%, based on 100% total weight of the first and second components, and is 60mm long glass fibers; the second component specifically comprises the following components in parts by weight:

matrix resin	100 portions of
		Graphene	5 portions of
Elastomer low profile additives	25 portions of
		Inorganic filler	180 portions of
Curing agent	20 portions of
		Internal mold release agent	3 portions of
Color paste	30 portions of
		Process aid	5 portions of
Thickening agent	8 portions of

Wherein the matrix resin is vinyl ester resin; the elastomer low-shrinkage additive is polyurethane; the inorganic filler is calcium carbonate, and the granularity of the inorganic filler is 100 meshes; the curing agent is dicumyl peroxide; the internal release agent is zinc stearate; the process aid is a process aid BYK-W9010; the thickener is magnesium hydroxide.

Wherein the color paste is prepared by mixing and developing a toner and matrix resin, and the content of the toner in the color paste is 20wt%.

Fig. 1 is a schematic flow chart of a process for preparing an SMC material of the present invention, and it can be seen that the process for preparing an SMC material of the present invention includes the following steps:

step S1: weighing the first component according to the formula, and cutting the glass fiber to 60mm by a cutter for later use; weighing each component of the second component according to the formula, and drying the solid at 50 deg.C for 3min for use.

Step S2: and dispersing graphene in the second component in ethylene glycol, and performing ultrasonic dispersion for 0.5h under the ultrasonic power of 1000W to obtain a graphene premix solution, wherein the content of the graphene is 5wt%.

And step S3: and (3) adding matrix resin into the graphene premixed liquid obtained in the step (S2), stirring for 20min at the rotating speed of 1500r/min to mix, then adding the elastomer low-shrinkage additive, the curing agent, the internal release agent, the color paste and the process auxiliary agent, mixing and stirring for 10min, then adding the inorganic filler, continuously stirring for 15min, finally adding the thickening agent, adjusting the stirring speed to be 500r/min, and stirring until the system temperature reaches 40 ℃ to obtain the resin paste.

And step S4: respectively and uniformly coating a layer of resin paste obtained in the step S3 on two polyethylene films, uniformly dispersing the glass fibers prepared in the step S1 on the resin paste of one polyethylene film, coating two layers of resin pastes (to control the thickness of the SMC material) on the surface of the polyethylene film on which the glass fibers are dispersed according to actual conditions, covering with the other polyethylene film (with the surface coated with the resin paste), dispersing the glass fibers between the resin pastes on the two polyethylene films, scraping the outer surface of the polyethylene film with a scraper to discharge air bubbles, and completely impregnating the glass fibers in the resin paste to prepare the SMC sheet.

Step S5: and (5) performing die pressing and rolling on the SMC sheet obtained in the step (S4) to obtain a sheet molding compound, and then moving the sheet molding compound into a drying room for curing to obtain the SMC material, wherein in the step, the temperature of the die pressing is 150 ℃, the pressure of the die pressing is 20MPa, and the time of the die pressing per millimeter is 60S.

Specific example 3

The SMC material in this example includes a first component and a second component, wherein the first component comprises 45%, based on 100% total weight of the first and second components, and is 30mm long glass fibers; the second component specifically comprises the following components in parts by weight:

matrix resin	100 portions of
		Graphene	3 portions of
Elastomer low profile additives	20 portions of
		Inorganic filler	160 portions of
Curing agent	18 portions of
		Internal mold release agent	2 portions of
Color paste	15 portions of
		Process aid	3 portions of
Thickening agent	5 portions of

Wherein the matrix resin is polyimide resin; the elastomer low-shrinkage additive is polyurethane; the inorganic filler is calcium carbonate, and the granularity of the inorganic filler is 80 meshes; the curing agent is tert-butyl peroxybenzoate; the internal release agent is calcium stearate; the process auxiliary agent is a process auxiliary agent BYK-W996; the thickener is calcium hydroxide.

Wherein the color paste is prepared by mixing and developing a toner and matrix resin, and the content of the toner in the color paste is 10wt%.

step S1: weighing the first component according to the formula, and cutting the glass fiber to 30mm by a cutter for later use; weighing each component of the second component according to the formula, and drying the solid at 45 deg.C for 4 min.

Step S2: and dispersing graphene in the second component in methyl methacrylate, and performing ultrasonic dispersion for 2 hours under the ultrasonic power of 800W to obtain a graphene premix, wherein the content of the graphene is 2wt%.

And step S3: and (3) adding matrix resin into the graphene premixed liquid obtained in the step (S2), stirring for 15min at the rotating speed of 1300r/min to mix, then adding the elastomer low-shrinkage additive, the curing agent, the internal release agent, the color paste and the process auxiliary agent, mixing and stirring for 8min, then adding the inorganic filler, continuously stirring for 12min, finally adding the thickening agent, adjusting the stirring speed to 300r/min, and stirring until the system temperature reaches 42 ℃ to obtain the resin paste.

Step S5: and (5) performing die pressing and rolling on the SMC sheet obtained in the step (S4) to obtain a sheet molding compound, and then moving the sheet molding compound into a drying room for curing to obtain the SMC material, wherein in the step, the temperature of the die pressing is 145 ℃, the pressure is 10MPa, and the time of the die pressing per millimeter is 30S.

Comparative example: the procedure was the same as that for the preparation in specific example 1, except that the SMC material of the comparative example included a first component and a second component, the first component accounting for 25% by weight and being 10mm long glass fiber, based on 100% by weight of the total of the first component and the second component; the second component specifically comprises the following components in parts by weight:

matrix resin	100 portions of
		Low profile additive	12 portions of
Inorganic filler	100 portions of
		Curing agent	15 portions of
Internal mold release agent	1 part of
		Color paste	2 portions of
Process aid	1 part of
		Thickening agent	1 part of

Wherein the matrix resin is epoxy resin; the low shrinkage additive is polystyrene; the inorganic filler is aluminum hydroxide, and the granularity of the inorganic filler is 50 meshes; the curing agent is tert-butyl peroxybenzoate; the internal release agent is calcium stearate; the process auxiliary agent is a process auxiliary agent BYK-W996; the thickening agent is magnesium oxide; wherein the color paste is prepared by mixing and developing a toner and matrix resin, and the content of the toner in the color paste is 5wt%.

The SMC materials obtained above were examined for their correlation properties, and the resulting structures are shown in Table 1.

TABLE 1 table of mechanical Properties of materials of SMC materials

As can be seen from the above embodiments of the present invention, the overall performance of the SMC material prepared by the present invention is enhanced; therefore, the elastomer low-shrinkage additive is added, so that the curing shrinkage can be reduced, the surface of the SMC material is optimized, the toughness, the impact resistance and the fracture resistance of the SMC material are enhanced, and the coloring condition of the SMC material can be improved; in addition, the elastomer low-shrinkage additive can also improve the flow property in a system so as to increase the addition amount of inorganic filler and glass fiber and reduce the production cost, and the glass fiber with longer length can be adopted to enhance the strength of the SMC material, and the addition of graphene is matched to further enhance the strength of the SMC material so as to make up the problem of mechanical strength reduction caused by the elastomer low-shrinkage additive, so that the SMC material with enhanced performance is obtained.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can understand that the changes or modifications within the technical scope of the present invention are included in the scope of the present invention, and therefore, the scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An SMC material, characterized by: comprises a first component and a second component, wherein the first component accounts for 35-60 percent calculated by taking the total weight of the first component and the second component as 100 percent;

wherein the second component comprises the following components in parts by weight: 100 parts of matrix resin, 2-5 parts of graphene, 12-25 parts of elastomer low-shrinkage additive, 120-180 parts of inorganic filler, 15-20 parts of curing agent, 1-3 parts of internal release agent, 2-30 parts of color paste, 1-5 parts of process aid and 1-8 parts of thickening agent.

2. An SMC material as in claim 1 wherein: the matrix resin is one of epoxy resin, vinyl ester resin or polyimide resin.

3. An SMC material as in claim 1 wherein: the elastomeric low profile additive is a polyurethane.

4. An SMC material as in claim 1 wherein: the inorganic filler is one of aluminum hydroxide or calcium carbonate, and the granularity of the inorganic filler is 50-100 meshes.

5. An SMC material as in claim 1 wherein: the curing agent is one of tert-butyl peroxybenzoate or dicumyl peroxide; the internal release agent is one of calcium stearate or zinc stearate; the process auxiliary agent is one of process auxiliary agent BYK-W996 or process auxiliary agent BYK-W9010; the thickening agent is one of magnesium oxide, magnesium hydroxide or calcium hydroxide.

6. An SMC material as in claim 1 wherein: the color paste is prepared by mixing and developing a toner and a matrix resin, and the content of the toner in the color paste is 5-20wt%.

7. A process for the preparation of an SMC material, in order to prepare an SMC material as claimed in any of claims 1 to 6, wherein: the method comprises the following steps:

(3) Adding matrix resin into the graphene premixed liquid obtained in the step (2), stirring for 10-20min at the rotating speed of 1200-1500r/min to mix, then adding the elastomer low-shrinkage additive, the curing agent, the internal release agent, the color paste and the process auxiliary agent, mixing and stirring for 5-10min, then adding the inorganic filler, continuously stirring for 10-15min, finally adding the thickening agent, adjusting the stirring speed to 100-500r/min, and stirring until the system temperature is below 45 ℃ to obtain resin paste;

(4) Respectively and uniformly coating a layer of resin paste obtained in the step (3) on two polyethylene films, uniformly dispersing glass fibers prepared in the step (1) on the resin paste of one polyethylene film, coating at least one layer of resin paste on the surface of the polyethylene film with the glass fibers dispersed, covering with the other polyethylene film coated with the resin paste, scraping the outer surface of the polyethylene film by using a scraper to discharge bubbles, and completely soaking the glass fibers in the resin paste to prepare an SMC sheet;

8. A process for preparing an SMC material as in claim 7 wherein: in the step (2), the organic solution is one of styrene, ethylene glycol or methyl methacrylate.

9. A process for preparing an SMC material as in claim 8 wherein: the graphene content in the graphene premix liquid in the step (2) is 0.5-5wt%.

10. A process for preparing an SMC material as in claim 7 wherein: the temperature of the die in the step (5) is 140-150 ℃, the pressure of the die is 5-20MPa, and the time of the die per millimeter of thickness is 4-60s.