SMC material based on recycled BMC, SMC molded part and production process

Abstract

The invention discloses an SMC material based on recycled BMC. The SMC material comprises resin paste and reinforced fibers, the main components of the resin paste comprise unsaturated polyester resin, thermoplastic resin, recycled BMC powder, a low-shrinkage additive, styrene, a filler, an auxiliary agent and reinforced fibers; the auxiliaries mainly comprise a curing agent, a release agent, a thickening agent and a polymerization inhibitor; the base material resin of the recycled BMC powder comprises unsaturated polyester resin and thermoplastic resin. According to the SMC material based on the recovered BMC, unsaturated polyester resin and thermoplastic resin which are the same as BMC powder base material resin are introduced into the SMC material, so that the compatibility of the recovered BMC powder and other components in resin paste is improved; and the prepared molded part is smooth in surface and excellent in appearance and mechanical property. The invention further discloses an SMC forming part and a forming part production process.

Description

Technical Field

[0001] The invention relates to the field of BMC recycling, and in particular to an SMC material based on recycled BMC, an SMC molded part and a production process. Background Art

[0002] BMC (Bulk Molding Compound) is bulk molding compound, and SMC (Sheet Molding Compound) is sheet molding compound. The formulas of both mainly include thermosetting resin, glass fiber reinforcement material, filler and additives, and both are mainly formed by compression molding. However, BMC is more suitable for making high-precision and complex components due to its excellent fluidity, while SMC is suitable for making large and complex parts.

[0003] With the increasing use of BMC / SMC composite materials, the urgency of waste recycling is increasing. There are two main methods for recycling thermosetting resin composite materials: one is the physical method, that is, the waste crushed resin is used as part of the filler; the other is the chemical method, the waste is cracked to recover the raw materials, such as cracking gas, pyrolysis oil and solid by-products. Thermoplastic resins can be heated, melted and finally processed again, and recycling is relatively easy compared to thermosetting resins, but they are usually used to manufacture products with lower mechanical strength requirements.

[0004] The recycling of composite materials containing both thermoplastic resins and thermosetting resins has the following problems: First, when the recycled crushed materials are added to the new thermoplastic resin materials to prepare SMC, the surface of the molded parts has obvious bumps and depressions, which cannot be applied to the production of parts with high requirements for appearance; Second, because the recycled crushed materials undergo natural degradation and aging, the molecular chain structure changes, and they are usually used to process products with slightly lower performance requirements than new materials, such as products with slightly worse mechanical properties. Summary of the invention

[0005] One of the purposes of the present invention is to overcome the defects in the prior art and provide an SMC material based on recycled BMC, wherein the crushed material of the recycled BMC is used as a component of the SMC resin paste, the crushed material and the new material of the SMC material contain the same unsaturated polyester resin and thermoplastic resin, and the surface flatness and mechanical strength of the SMC molded parts manufactured with the crushed material are improved.

[0006] In order to achieve the above technical effects, the technical solution of the present invention is: an SMC material based on recycled BMC, including resin paste and reinforcing fibers; The main components of the resin paste include unsaturated polyester resin, thermoplastic resin, recycled BMC powder, low shrinkage additive, styrene, filler, additives and reinforcing fiber; the additives mainly include curing agent, release agent, thickener and inhibitor; The base resin of the recycled BMC powder comprises the unsaturated polyester resin and the thermoplastic resin.

[0007] The preferred technical solution is that the raw material composition of the recycled BMC powder does not contain a thickener.

[0008] The preferred technical solution is that the mass of the unsaturated polyester resin of the SMC material is M1, the sum of the mass of the thermoplastic resin in the recycled BMC powder and the thermoplastic resin in the resin paste is M2, and the ratio of M1 to M2 is 1: (0.3-2). The optional ratio of M1 to M2 is 1:0.3, 1:0.55, 1:0.7, 1:0.85, 1:0.9, 1:1, 1:1.2, 1:1.5, 1:1.75, 1:2 point values ​​and the interval of the maximum and minimum values ​​of the two point values. Further, the ratio of M1 to M2 is 1: (0.55-1.75); further, it is 1: (0.85-1.4).

[0009] The preferred technical solution is that the sum of the mass of the unsaturated polyester resin, thermoplastic resin and thermoplastic resin in the resin paste and the recycled BMC powder is M3, the sum of the mass of the recycled BMC powder excluding the thermoplastic resin and the filler mass of the SMC material is M4, and the ratio of M3 to M4 is 1: (1-2.05). The optional ratio of M3 to M4 is 1:1, 1:1.25, 1:1.5, 1:1.75, 1:2, 1:2.05 point values ​​and the interval of the two point values ​​as the maximum and minimum values. Further, the ratio of M3 to M4 is 1: (1.2-2.03), and further 1: (1.6-2).

[0010] The preferred technical solution is that the mass percentage of the thermoplastic resin in the recycled BMC powder is 3% to 20%; the sum of the masses of the unsaturated polyester resin and the thermoplastic resin in the resin paste is M5, and the mass ratio of M5 to the recycled BMC powder is 1:(0.65 to 0.9), further the mass ratio is 1:(0.65 to 0.8), and further the mass ratio is 1:(0.65 to 0.75).

[0011] The mass percentage of the thermoplastic resin in the recycled BMC powder is 3%, 5%, 7%, 10%, 13%, 15%, 17%, 20% and a range with two points as the maximum and minimum values. Further, the mass percentage of the thermoplastic resin in the recycled BMC powder is 5% to 17%, and further 7% to 15%.

[0012] The preferred technical solution is that, by weight, the resin paste comprises: 100 parts of unsaturated polyester resin, 50-160 parts of thermoplastic resin, 125-180 parts of recycled BMC powder, 30-80 parts of low shrinkage additive, 5-50 parts of styrene, and 120-400 parts of filler; the auxiliary agent comprises 1-8 parts of curing agent, 4-17 parts of release agent, 0.5-10 parts of thickener, and 0.1-5 parts of inhibitor.

[0013] Furthermore, the composition of the resin paste includes: 100 parts of unsaturated polyester resin, 70-130 parts of thermoplastic resin, 125-160 parts of recycled BMC powder, 40-70 parts of low shrinkage additive, 10-40 parts of styrene, and 170-300 parts of filler; the auxiliary agents include 2-6 parts of curing agent, 6-14 parts of release agent, 0.5-5 parts of thickener, and 0.2-3 parts of inhibitor.

[0014] A preferred technical solution is that the thermoplastic resin is a thermoplastic acrylate resin.

[0015] The preferred technical solution is that the mass ratio of the resin paste to the reinforcing fiber is (2.5-6):1. The mass ratio of the resin paste to the reinforcing fiber can be selected from 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1 point values ​​and an interval with two point values ​​as the maximum and minimum values. Further, the mass ratio of the resin paste to the reinforcing fiber is (3-5.5):1, and further (3-5):1.

[0016] The preferred technical solution is that the release agent is zinc stearate; and / or the thickener comprises magnesium oxide and a carrier resin; and / or the inhibitor is a p-benzoquinone solution; and / or the low shrinkage additive is at least one selected from polyvinyl acetate and saturated polyester; and / or the filler is calcium carbonate; And / or the curing agent is a tert-butyl ester curing agent.

[0017] The preferred technical solution is that the particle size of the recycled BMC powder is 50-400 mesh, and the particle size of the filler is smaller than the particle size of the recycled BMC powder. Further, the particle size of the recycled BMC powder is 100-300 mesh, and further 100-200 mesh. The particle size of the filler is 500-1000 mesh, and further 650-950 mesh.

[0018] A second object of the present invention is to provide an SMC molded part obtained by curing the above-mentioned SMC material.

[0019] The third object of the present invention is to provide a production process of SMC molded parts based on recycled BMC, based on the above-mentioned SMC material, including the following steps of preparing resin paste: S1: Mix the other components in the resin paste except the recovered BMC powder, filler and thickener to obtain a mixed solution; S2: adding the recovered BMC powder into the mixed solution and mixing well to obtain the first paste; S3: taking out a predetermined amount of filler, adding the remaining filler to the first paste, and mixing to obtain a second paste; S4: preparing a thickening paste by adding a thickener and a predetermined amount of filler in S3; S5: Add the thickened paste to the second paste with online stirring to obtain a resin paste.

[0020] The advantages and beneficial effects of the present invention are: The SMC material based on recycled BMC is based on recycled BMC powder. By introducing unsaturated polyester resin and thermoplastic resin, which are the same as the BMC powder base resin, into the SMC material, the compatibility of the recycled BMC powder with other components in the resin paste is improved. Compared with the resin paste containing only thermoplastic resin by recycling BMC powder, the molded parts made based on the resin paste have a smooth surface and excellent appearance, which is suitable for the production of automotive parts with higher appearance requirements; By optimizing the formula of resin paste, the amount of resin paste and reinforcing fiber, the tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength and other properties of SMC molded parts can be improved, so that the mechanical properties can reach similar or better than those of new material molded parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a photograph of a thermoplastic SMC molded part containing recycled BMC in Comparative Example 1; Figure 2 This is a photo of the SMC molded part of Comparative Example 3 that does not contain recycled BMC powder; Figure 3 This is a photo of the SMC molded part containing recycled BMC powder in Example 1. DETAILED DESCRIPTION

[0022] The specific implementation of the present invention is further described below in conjunction with the examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present invention.

[0023] Production of recycled BMC powder The recycled BMC powder contains thermoplastic resin, which is suitable for producing small parts such as bracket modules. In the process of producing powder, the temperature of the crushing equipment needs to be strictly controlled to be as low as possible to avoid the softening and bonding of thermoplastic resin during the powder production process. It can be understood that the production of large-volume BMC waste parts into powder includes the steps of cutting, crushing and grinding in sequence.

[0024] Preferably, the recycling of waste parts crushing process includes at least four steps of crushing products gradually reduced: 1) Cut the recycled parts into small pieces with a side length of about 2 cm; 2) Break small pieces of parts into pieces; 3) The crushed parts are introduced into the primary grinding equipment to obtain primary grinding powder with a particle size of about 10 mesh; 4) The primary powder is further finely ground to obtain the recovered BMC powder with a particle size of 100-200 mesh.

[0025] Based on the production steps of adding recycled BMC powder first and then adding filler in the resin paste preparation step, when the raw material of the recycled BMC powder contains a thickener component, the addition of the recycled BMC powder to the mixture of the thickener and filler will cause the mixture to thicken prematurely, thereby causing a large amount of large filler to be unable to be evenly dispersed in the mixture.

[0026] Resin paste and reinforcing fiber Taking the SMC production process as an example, first, the resin paste layer is scraped on the surface of the upper and lower carrier films respectively; then the chopped fibers are sprinkled on the resin paste layer; finally, the resin paste layers of the upper and lower carrier films are pressed relative to each other, vented, extruded and impregnated, and cured to obtain the SMC finished product.

[0027] Reinforcement fiber is the main reinforcement material in SMC molded parts, including but not limited to glass fiber, basalt fiber, carbon fiber, bio-fiber and other known reinforcement fiber varieties.

[0028] Thermoplastic resin The thermoplastic resin can be any known resin blended with unsaturated polyester resin to produce SMC resin paste. Preferably, the thermoplastic resin is a thermoplastic acrylate resin.

[0029] The order of adding recycled BMC powder and filler in the process of preparing resin paste The order of adding recycled BMC powder and filler mainly includes two types: first recycling powder and then filler, and first filler and then recycling powder. On the basis that the particle size of recycled BMC powder is smaller than that of filler, and the amount of recycled BMC powder added is smaller than that of filler, compared with first recycling powder and then filler, adding filler to the mixed liquid other than filler and thickener first will lead to a rapid increase in the viscosity of the mixed paste system, thereby increasing the difficulty of dispersing recycled BMC powder in the above paste system. Example

[0030] By weight, the composition of the recycled BMC is 10 parts of thermoplastic acrylate resin (ARKEMA Elium 590), 16 parts of unsaturated polyester resin (AOC p17-963), 15 parts of low shrinkage additive (AOC H2075), 0.3 parts of curing agent tert-amyl peroxide 2-ethylhexanoate (luperox 575), 1 part of mold release agent zinc stearate (Guangdong Hanwei), 30 parts of filler calcium carbonate (Jiangsu Lida, 800 mesh), 27 parts of glass fiber (Taishan T950, linear density of 4400tex), and the mass percentage of thermoplastic acrylate resin in the recycled BMC powder is 10%; the particle size of the recycled BMC powder obtained by screening is 100-200 mesh. BMC material curing conditions: molding temperature 115℃, holding time 6min.

[0031] Example 1 The production process of SMC molded parts based on recycled BMC is as follows: S01: Prepare resin paste components: 50 parts of unsaturated polyester resin (Changzhou Huake Polymer, HS1500), 50 parts of thermoplastic acrylate resin (Arkema, Elium 590), 70 parts of recycled BMC powder, 30 parts of low shrinkage additive polyvinyl acetate (Changzhou Huake Polymer, HS 9892, saturated polyester type), 10 parts of styrene (Zhejiang Petrochemical), 140 parts of filler calcium carbonate (Jiangsu Lida, 800 mesh); 1.5 parts of auxiliary curing agent tert-butyl peroxybenzoate (Nouryon), 4.5 parts of mold release agent zinc stearate (Guangdong Hanwei), 1 part of inhibitor p-benzoquinone solution (mass percentage 5% p-benzoquinone + 95% styrene), 2 parts of thickening paste [thickening agent magnesium oxide (ICL, Israel, RA150, 325 mesh), filler calcium carbonate (Jiangsu Lida, 800 mesh) and carrier resin (AOC9286) mass ratio 3:3:4)]; 100 pieces of glass fiber [Taishan T950, linear density (GB / T 7690.1-2001) is 4400tex, cut into length 25mm] are also configured; S02: unsaturated polyester resin, thermoplastic acrylate resin, low shrinkage additive, curing agent, zinc stearate, styrene, and p-benzoquinone solution in S01 are added in sequence, stirred for 20 minutes, and mixed to obtain a mixed solution; S03: Add the recovered BMC powder to the mixed solution, stir for 5 minutes, and mix well to obtain the first paste; S04: adding part of calcium carbonate as a filler to the first paste, stirring for 20 minutes, and mixing to obtain a second paste; S05: mixing calcium carbonate as a thickening paste component with a thickener and a carrier resin to obtain a thickening paste; S06: adding the thickened paste to the second paste by stirring online to obtain a resin paste; S07: introduce the carrier film into the scraper groove, apply a 1mm layer of resin paste on one surface of the carrier film, cut the glass fiber to obtain chopped fibers (length 20±2mm), sprinkle the chopped fibers onto the resin paste layer according to the ratio, and then introduce the two layers of carrier film into the sheet composite line, and obtain the SMC coil after the sheet line is vented, extruded, impregnated, and rolled up.

[0032] The raw material suppliers and models in the following comparative examples and embodiment 1 are the same as those in embodiment 1.

[0033] like Figure 3 As shown, the thermoplastic SMC molded part obtained in Example 1 has a smooth surface and excellent appearance, and is suitable for producing automotive surface parts with high appearance requirements.

[0034] Comparative Example 1 The resin paste of Comparative Example 1 does not contain unsaturated polyester resin, and the resin paste is composed of: 100 parts of thermoplastic acrylate resin, 70 parts of recycled BMC powder, 30 parts of low shrinkage additive polyvinyl acetate (PVAc), 10 parts of styrene, 140 parts of 800 mesh calcium carbonate filler; 1.5 parts of auxiliary curing agent tert-butyl peroxybenzoate, 4.5 parts of release agent zinc stearate, 1 part of inhibitor p-benzoquinone solution, 2 parts of thickening paste (magnesium oxide, filler calcium carbonate and carrier resin mass ratio of 3:3:4); Based on the total amount of the resin paste, 100 parts of glass fiber were added according to a mass ratio.

[0035] The SMC coil was produced based on the production steps of Example 1.

[0036] The models of the thermoplastic acrylic resin, low shrinkage additive polyvinyl acetate, filler calcium carbonate and other components in Comparative Example 1 are the same as those in Example 1.

[0037] In Comparative Example 1, the SMC resin paste does not contain unsaturated polyester resin, and the thermoplastic resin of the SMC raw material component shrinks significantly. Figure 1 As shown, the thermoplastic SMC molded part obtained in Comparative Example 1 has obvious concavities and convexities.

[0038] Comparative Example 2 The resin paste of comparative example 2 does not contain thermoplastic acrylic resin, and the resin paste is composed of: 100 parts of unsaturated polyester resin, 70 parts of recycled BMC powder, 30 parts of low shrinkage additive polyvinyl acetate (PVAc), 10 parts of styrene, 140 parts of 800 mesh calcium carbonate filler; 1.5 parts of auxiliary curing agent tert-butyl peroxybenzoate, 4.5 parts of release agent zinc stearate, 1 part of inhibitor p-benzoquinone solution, 2 parts of thickening paste (magnesium oxide, filler calcium carbonate and carrier resin mass ratio of 3:3:4); Based on the total amount of resin paste, 100 parts of glass fiber is configured.

[0039] The SMC coil was produced based on the production steps of Example 1.

[0040] Comparative Example 3 The resin paste of Comparative Example 3 does not contain recycled BMC powder, and 70 parts of recycled BMC powder are replaced by 7 parts of thermoplastic acrylate resin and 63 parts of calcium carbonate.

[0041] The resin paste of Comparative Example 3 is composed of: 50 parts of unsaturated polyester resin, 57 parts of thermoplastic acrylate resin, 30 parts of low shrinkage additive polyvinyl acetate (PVAc), 10 parts of styrene, 203 parts of 800 mesh calcium carbonate filler; 1.5 parts of auxiliary curing agent tert-butyl peroxybenzoate, 4.5 parts of mold release agent zinc stearate, 1 part of inhibitor p-benzoquinone solution, 2 parts of thickening paste (magnesium oxide, filler calcium carbonate and carrier resin mass ratio of 3:3:4); Based on the total amount of resin paste, 100 parts of glass fiber is configured.

[0042] The SMC coil was produced based on the production steps of Example 1.

[0043] like Figure 2 As shown, the surface of the thermoplastic SMC molded part obtained in Comparative Example 3 is smooth, and the degree of smoothness is similar to that of Example 1, without the concave-convex problem of Comparative Example 1.

[0044] Embodiments 2 to 4 The resin paste components of Example 2 are: 50 parts of unsaturated polyester resin, 50 parts of thermoplastic acrylate resin, 80 parts of recycled BMC powder, 30 parts of low shrinkage additive polyvinyl acetate (PVAc), 10 parts of styrene, 140 parts of 800 mesh calcium carbonate filler; 1.5 parts of auxiliary curing agent tert-butyl peroxybenzoate, 4.5 parts of mold release agent zinc stearate, 1 part of inhibitor p-benzoquinone solution, 2 parts of thickening paste (magnesium oxide, filler calcium carbonate and carrier resin mass ratio of 3:3:4); in addition to the paste, 100 parts of glass fiber are configured as the reinforcing fiber of the SMC coil.

[0045] The resin paste components of Example 3 are: 50 parts of unsaturated polyester resin, 50 parts of thermoplastic acrylate resin, 90 parts of recycled BMC powder, 30 parts of low shrinkage additive polyvinyl acetate (PVAc), 10 parts of styrene, 140 parts of 800 mesh calcium carbonate filler; 1.5 parts of auxiliary curing agent tert-butyl peroxybenzoate, 4.5 parts of mold release agent zinc stearate, 1 part of inhibitor p-benzoquinone solution, 2 parts of thickening paste (mass ratio of magnesium oxide, filler calcium carbonate and carrier resin 3:3:4); in addition to the paste, 100 parts of glass fiber are configured as reinforcing fiber of SMC coil.

[0046] The resin paste components of Example 4 are: 50 parts of unsaturated polyester resin, 50 parts of thermoplastic acrylate resin, 100 parts of recycled BMC powder, 30 parts of low shrinkage additive polyvinyl acetate (PVAc), 10 parts of styrene, 140 parts of 800 mesh calcium carbonate filler; 1.5 parts of auxiliary curing agent tert-butyl peroxybenzoate, 4.5 parts of release agent zinc stearate, 1 part of inhibitor p-benzoquinone solution, 2 parts of thickening paste (mass ratio of magnesium oxide, filler calcium carbonate and carrier resin 3:3:4); in addition to the paste, 100 parts of glass fiber are configured as reinforcing fiber of SMC coil.

[0047] The curing process of the SMC coils of the embodiment and the comparative example is as follows: the press specification is 150T, the pressure is 15KPa, the molding temperature of the upper and lower molds is 155°C, and the holding time is 100s.

[0048] Performance tests and test standards of SMC molded parts obtained in the examples and comparative examples: Tensile strength, tensile modulus: GB / T 1447-2005, splines are type II splines; Flexural strength, flexural modulus: GB / T 1449-2005, specimen 80 mm *15 mm; Impact strength: GB / T1043-2008, strip 80 mm *10 mm, no notch impact; Density: GB / T 1463-2005, sample strip 30mm*30mm, buoyancy method.

[0049] Comparative Example 1: Photos of SMC molded parts Figure 1 As shown; Comparative Example 3 SMC molded parts Figure 2 As shown; Example 1 The photo of SMC molded parts is as follows Figure 3 shown.

[0050] The performance test results of the SMC molded parts of Example 1, Comparative Examples 2 and 3 are shown in Table 1 below: Table 1

[0051] The resin base material of the resin paste in Comparative Example 2 is only 100 parts of unsaturated polyester resin, while Example 1 contains 50 parts of unsaturated polyester resin and 50 parts of thermoplastic acrylate resin. Compared with Example 1, the unsaturated polyester resin in Comparative Example 2 has a higher degree of crosslinking. Generally, the higher the degree of crosslinking, the tighter the connection between the resin molecular chains, resulting in a decrease in the voids inside the material and a corresponding increase in density. Therefore, the density of the SMC molded part in Example 2 is significantly higher than that in Example 1.

[0052] The content of thermoplastic acrylate resin in Comparative Example 3 is higher than that in Example 1. The molecular chains of thermoplastic acrylate resin are blended between the molecular chains of unsaturated polyester resin, resulting in a lower degree of crosslinking of the unsaturated polyester resin. At the same time, the density of thermoplastic acrylate resin itself is relatively low. Therefore, the density of the SMC molded part of Comparative Example 3 is slightly lower than that of Example 1. The mechanical performance parameters of Example 1 are close to those of Comparative Example 3, wherein the bending modulus of the sample of Example 1 is better than that of Comparative Example 3.

[0053] The performance test results of the SMC molded parts of Examples 1-4 are shown in Table 2 below: Table 2

[0054] As shown in Table 2, with the increase of the amount of recycled BMC powder, the tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength and density of the SMC molded parts all show a decreasing trend, among which the attenuation difference of flexural strength, flexural modulus and impact strength gradually increases. The flexural strength and impact strength of Example 2 are close to those of Example 1.

[0055] The larger the amount of recycled BMC powder used in Examples 1-4, the lower the density of the recycled BMC is than that of SMC. At the same time, the larger the particle size of the recycled BMC powder relative to the filler, the more pores are introduced into the molded parts. Therefore, the density of Examples 1-4 gradually decreases.

[0056] Without changing the content of other components, the performance of the SMC molded part of Example 1 reaches or approaches that of new materials. If the amount of recycled BMC powder is further reduced based on Example 1, the density difference between the SMC molded part containing recycled powder and the new material molded part is greater, which is contrary to the lightweight requirements of automotive parts. Considering the density and mechanical strength of the molded part, 70 parts of recycled powder in the resin paste of Example 1 is the best ratio to maintain the comprehensive performance of the SMC molded part.

[0057] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A SMC material based on recycled BMC, characterized in that: including resin paste and reinforcing fibers; The main components of the resin paste include unsaturated polyester resin, thermoplastic resin, recycled BMC powder, low shrinkage additive, styrene, filler, additives and reinforcing fiber; the additives mainly include curing agent, release agent, thickener and inhibitor; The base resin of the recycled BMC powder comprises the unsaturated polyester resin and the thermoplastic resin; The mass of the unsaturated polyester resin of the SMC material is M1, the sum of the mass of the thermoplastic resin in the recycled BMC powder and the thermoplastic resin in the resin paste is M2, and the ratio of M1 to M2 is 1:(0.3-2); The thermoplastic resin is a thermoplastic acrylate resin.

2. The SMC material based on recycled BMC according to claim 1, characterized in that: The raw material composition of the recycled BMC powder does not contain a thickener.

3. The SMC material based on recycled BMC according to claim 1, characterized in that: The sum of the mass of the unsaturated polyester resin, the thermoplastic resin and the thermoplastic resin in the recycled BMC powder of the resin paste is M3, the sum of the mass of the recycled BMC powder excluding the thermoplastic resin and the filler mass of the SMC material is M4, and the ratio of M3 to M4 is 1:(1-2.05).

4. The SMC material based on recycled BMC according to claim 1, characterized in that: The mass percentage of the thermoplastic resin in the recycled BMC powder is 3% to 20%; the sum of the masses of the unsaturated polyester resin and the thermoplastic resin in the resin paste is M5, and the mass ratio of M5 to the recycled BMC powder is 1:(0.65 to 0.9).

5. The SMC material based on recycled BMC according to claim 1, characterized in that: The resin paste comprises, by weight, 100 parts of unsaturated polyester resin, 50-160 parts of thermoplastic resin, 125-180 parts of recycled BMC powder, 30-80 parts of low shrinkage additive, 5-50 parts of styrene, and 120-400 parts of filler; The auxiliary agent comprises 1 to 8 parts of a curing agent, 4 to 17 parts of a release agent, 0.5 to 10 parts of a thickener, and 0.1 to 5 parts of an inhibitor.

6. The SMC material based on recycled BMC according to claim 1, characterized in that: The mass ratio of the resin paste to the reinforcing fiber is (2.5-6):

1.

7. The SMC material based on recycled BMC according to claim 1, characterized in that: The release agent is zinc stearate; and / or the thickener comprises magnesium oxide and a carrier resin; and / or the inhibitor is a p-benzoquinone solution; and / or the low shrinkage additive is at least one selected from polyvinyl acetate and saturated polyester; and / or the filler is calcium carbonate; And / or the curing agent is a tert-butyl ester curing agent.

8. The SMC material based on recycled BMC according to claim 1, characterized in that: The particle size of the recycled BMC powder is 50-400 meshes, and the particle size of the filler is smaller than that of the recycled BMC powder.

9. An SMC molded part, characterized in that: It is obtained by curing the SMC material described in any one of claims 1 to 8.

10. A process for producing SMC molded parts based on recycled BMC, characterized in that: The SMC material according to any one of claims 1 to 8 comprises the following steps of preparing the resin paste: S1: Mix the other components in the resin paste except the recovered BMC powder, filler and thickener to obtain a mixed solution; S2: adding the recovered BMC powder into the mixed solution and mixing well to obtain the first paste; S3: taking out a predetermined amount of filler, adding the remaining filler to the first paste, and mixing to obtain a second paste; S4: preparing a thickening paste by adding a thickener and a predetermined amount of filler in S3; S5: Add the thickened paste to the second paste with online stirring to obtain a resin paste.

Images