Low-density BMC (bulk molding compound) and preparation method thereof

Abstract

The invention relates to the field of BMC molding compounds, in particular to a preparation method of a low-density BMC molding compound. The low-density BMC comprises the following components in parts by mass: 15-17 parts of unsaturated polyester resin, 5-7 parts of low-shrinkage resin, 1.5-2 parts of zinc stearate, 8-10 parts of bamboo powder, 25-35 parts of aluminum hydroxide, 25-30 parts of calcium carbonate, 0.3-0.5 part of a curing agent, 0.3-0.7 part of an inhibitor, a plurality of pigments and 5-10 parts of glass fibers. The density is reduced through the bamboo powder, and the cost is greatly reduced.

Description

Technical Field

[0001] The invention relates to the field of BMC molding materials, and in particular to a preparation method of a low-density BMC molding material. Background Art

[0002] BMC molding compound, also known as bulk molding compound, is a material widely used in the industrial field. It is a molding intermediate material for glass fiber reinforced thermosetting products manufactured by a semi-dry process. This material is mainly composed of unsaturated polyester resin, low shrinkage / low profile additives, initiators, internal release agents, mineral fillers and other ingredients pre-mixed into a paste, and then other ingredients such as thickeners and colorants are added. It is fully stirred with glass fibers of different lengths in a special material kettle, and after a thickening process, a bulk intermediate material is finally formed. This material has good plasticity and stability and is suitable for various molding and injection molding processes.

[0003] During the research and development process, low density is an important research direction. At present, most of the low-density BMC molding compounds available on the market use the method of adding hollow glass microspheres to achieve low density. However, the cost of this method is relatively high, which limits its promotion in some cost-sensitive application fields. Therefore, researchers are working hard to find more economical and efficient alternatives to reduce production costs and improve the market competitiveness of products. Summary of the invention

[0004] The present invention hopes to provide a method for preparing a low-density BMC molding compound, and the specific scheme is as follows:

[0005] A low-density BMC molding compound comprises the following components in mass ratio: 15-17 of unsaturated polyester resin, 5-7 of low shrinkage resin, 1.5-2 of zinc stearate, 8-10 of bamboo powder, 25-35 of aluminum hydroxide, 25-30 of calcium carbonate, 0.3-0.5 of curing agent, 0.3-0.7 of inhibitor, some pigments and 5-10 of glass fiber.

[0006] The bamboo powder includes 100-mesh bamboo powder and 400-mesh bamboo powder, and the added mass ratio is 100-mesh bamboo powder: 400-mesh bamboo powder = 4:5.

[0007] The invention also comprises a treating agent, wherein the treating agent is HK-550 and BYK-9010, and the treating agent is used to treat the bamboo powder.

[0008] A method for preparing a low-density BMC molding compound, the specific steps are as follows:

[0009] (1) Surface treatment of bamboo powder: put bamboo powder into a disperser and add a treatment agent;

[0010] (2) adding unsaturated polyester resin, low shrinkage resin, curing agent and inhibitor, and stirring using a disperser;

[0011] (3) adding the material obtained in step (2) into a kneader, and adding zinc stearate, aluminum hydroxide, calcium carbonate, bamboo powder treated in step (1) and pigment in the formula, kneading and stirring;

[0012] (4) Add the glass fiber in the formula, continue kneading and stirring in a kneader to obtain a modified bulk molding compound.

[0013] The disperser in step (1) or (2) comprises a bracket, a cylinder mechanism is provided on the bracket, a lifting platform is provided on the cylinder mechanism, a motor frame is provided on the lifting platform, a first motor and a second motor are provided on the motor frame, a first stirring rod is provided at one end of the first motor, a top cover is provided on the motor frame, a gear turntable is provided at the edge of the top cover, the gear turntable is rotatably connected to the edge of the top cover, a driving wheel is provided at one end of the second motor, the driving wheel is meshed with the gear turntable, a plurality of driven wheels are provided on the top cover, the driven wheels are meshed with the gear turntable, and the second stirring rod is provided on both the driving wheel and the driven wheel.

[0014] A rotating disk is provided at the bottom of the first stirring rod, and a first stirring blade is provided on the rotating disk.

[0015] The second stirring rod is provided with a second stirring blade.

[0016] The bracket is provided with a fixing rod, the bracket is provided with a stirring tank body, the stirring tank body is provided with a fixing groove, and the fixing groove and the fixing rod are arranged in coordination.

[0017] The stirring speed of the disperser in step (1) or (2) is greater than 300 r / min, and the stirring speed of the bonding machine in step (3) or (4) is 28-35 r / min.

[0018] The present invention has the following advantages:

[0019] 1. The present invention reduces density by using bamboo powder, thus greatly reducing costs.

[0020] 2. Through research, it was found that the best effect is achieved by mixing bamboo powder with 100 mesh and 400 mesh in a mass ratio of 4:5. This is because different bamboo powders have different oil absorption rates. The larger the mesh size, the higher the oil absorption rate. The coarser the bamboo powder, the more friction pressure it can increase, so multiple mixtures are needed.

[0021] 3. After adding bamboo powder in the initial stage, we found that the color of the product was poor, so the bamboo powder needed to be pre-treated. Finally, we found that the addition of HK-550 and BYK-9010 treatment agents can solve the above problems, and after treatment, the oil absorption rate is reduced and it is better dispersed (if the dispersion is not good, the color will not be good).

[0022] 4. Most of the existing dispersers are single-axis with poor effect. There are also multi-axis dispersers in the prior art (such as double-axis, triple-axis, etc.), but these axes are actually driven by one motor, so the speeds of the above axes are the same. The faster speed of the disperser is to improve the dispersion effect, but since the speeds of the multiple axes are the same, the dispersion effect is actually quite general. The present invention drives the first stirring rod in the middle and several second stirring rods on the sides by dual motors to actually achieve the difference in the speeds of the two stirring rods (in practice, the speed of the first stirring rod is faster than the second stirring rod), and the dispersion effect is better.

[0023] 5. The bracket of the present invention is provided with a fixing rod, the bracket is provided with a stirring tank body, the stirring tank body is provided with a fixing groove, and the fixing groove and the fixing rod are arranged in coordination. This design is to fix the stirring tank body and prevent the stirring tank body from shaking during the dispersion process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of a disperser in a method for preparing a low-density BMC molding compound of the present invention;

[0025] Figure 2 It is a partial structural schematic diagram of a disperser in a method for preparing a low-density BMC molding compound of the present invention;

[0026] The numbers are as follows: 1. bracket; 2. cylinder mechanism; 3. lifting platform; 4. motor frame; 5. first motor; 6. second motor; 7. first stirring rod; 8. top cover; 9. gear turntable; 10. driving wheel; 11. driven wheel; 12. second stirring rod; 13. rotating disk; 14. first stirring blade; 15. second stirring blade; 16. fixing rod; 17. stirring tank body; 18. fixing groove. DETAILED DESCRIPTION

[0027] Example 1

[0028] A low-density BMC molding compound, the formula is as follows (mass ratio):

[0029]

[0030] A method for preparing a low-density BMC molding compound, the specific steps are as follows:

[0031] 1. Surface treatment of bamboo powder: Put bamboo powder into a high-speed disperser and add treatment agent (HK-550 and BYK-9010) to reduce the material absorption rate.

[0032] 2. Unsaturated polyester resin / low shrinkage resin / curing agent / inhibitor, stir for 10 minutes using a disperser.

[0033] 3. Add the material obtained in 2 into a kneader, and add zinc stearate / aluminum hydroxide / calcium carbonate / bamboo powder / pigment in the formula at the same time, and knead and stir for 25 minutes.

[0034] 4. Add the glass fiber in the formula, knead and stir for 10 minutes to modify the bulk molding compound.

[0035] The disperser includes a bracket 1, a cylinder mechanism 2 is provided on the bracket 1, a lifting platform 3 is provided on the cylinder mechanism 2, a motor frame 4 is provided on the lifting platform 3, a first motor 5 and a second motor 6 are provided on the motor frame 4, a first stirring rod 7 is provided at one end of the first motor 5, a top cover 8 is provided on the motor frame 4, a gear turntable 9 is provided on the edge of the top cover 8, the gear turntable 9 and the edge of the top cover 8 are rotatably connected, a driving wheel 10 is provided at one end of the second motor 6, the driving wheel 10 is meshed with the gear turntable 9, a plurality of driven wheels 11 are provided on the top cover 8, the driven wheels 11 are meshed with the gear turntable 9, and a second stirring rod 15 is provided on both the driving wheel 10 and the driven wheel 11. A rotating disk 13 is provided at the bottom of the first stirring rod 7, and a first stirring blade 14 is provided on the rotating disk 13. A second stirring blade 15 is provided on the second stirring rod 7. A fixing rod 16 is provided on the bracket 1, a stirring tank body 17 is provided on the bracket 1, and a fixing groove 18 is provided on the stirring tank body 17, and the fixing groove 18 and the fixing rod 16 are arranged in coordination.

[0036] The cylinder mechanism in the disperser drives the lifting platform to rise or fall. The lifting platform is raised when the mixing tank is installed, and is lowered for stirring and dispersing when dispersion is needed. The first stirring rod of the disperser is driven by the first motor to achieve stirring, and there are several second stirring rods (4 in the figure), including one second stirring rod driven by the driving wheel (the driving wheel is driven by the second motor), and the other second stirring rods are driven by the driven wheel (the driven wheel is driven because the driving wheel also drives the gear turntable), so the rotation speed of the first stirring rod and the second stirring rod can be different, so as to better stir (in practice, the speed of the first stirring rod will be greater than the speed of the second stirring rod).

[0037] Experimental Results

[0038]

[0039] Example 2-7 (The following examples are used to study the influence of bamboo powder mesh number on the product)

[0040] The other data of Examples 2-7 are the same as those of Example 1, except for the following data, which are detailed in the table:

[0041]

[0042]

[0043] Examples 8-9 (The following examples are used to study the effect of the treatment agent on the product)

[0044] The other data of Examples 8-9 are the same as those of Example 1, except for the following data, which are detailed in the table:

[0045]

[0046] The above content describes the technical principles, beneficial effects and features of the present invention. It should be pointed out that the above is only a preferred implementation mode of the present invention, but is not limited to the above embodiments. For technicians in the technical field to which the present invention belongs, some improvements and optimizations can be made without departing from the content of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A low-density BMC molding compound, characterized in that: The invention comprises the following components in mass ratio: 15-17 of unsaturated polyester resin, 5-7 of low shrinkage resin, 1.5-2 of zinc stearate, 8-10 of bamboo powder, 25-35 of aluminum hydroxide, 25-30 of calcium carbonate, 0.3-0.5 of curing agent, 0.3-0.7 of inhibitor, some pigments and 5-10 of glass fiber.

2. A low-density BMC molding compound as claimed in claim 1, characterized in that: The bamboo powder includes 100-mesh bamboo powder and 400-mesh bamboo powder, and the added mass ratio is 100-mesh bamboo powder: 400-mesh bamboo powder = 4:

5.

3. A low-density BMC molding compound as claimed in claim 1, characterized in that: The invention also comprises a treating agent, wherein the treating agent is HK-550 and BYK-9010, and the treating agent is used to treat the bamboo powder.

4. A method for preparing the low-density BMC molding compound as claimed in claim 1, characterized in that: The specific steps are as follows: (1) Surface treatment of bamboo powder: put bamboo powder into a disperser and add a treatment agent; (2) Add unsaturated polyester resin, low shrinkage resin, curing agent and inhibitor, and stir using a disperser; (3) adding the material obtained in step (2) into a kneader, and adding zinc stearate, aluminum hydroxide, calcium carbonate, bamboo powder treated in step (1) and pigment in the formula, kneading and stirring; (4) Add glass fiber in the formula and continue kneading and stirring in a kneader to obtain a modified bulk molding compound.

5. The method for preparing a low-density BMC molding compound according to claim 4, characterized in that: The disperser in step (1) or (2) comprises a bracket, a cylinder mechanism is provided on the bracket, a lifting platform is provided on the cylinder mechanism, a motor frame is provided on the lifting platform, a first motor and a second motor are provided on the motor frame, a first stirring rod is provided at one end of the first motor, a top cover is provided on the motor frame, a gear turntable is provided at the edge of the top cover, the gear turntable is rotatably connected to the edge of the top cover, a driving wheel is provided at one end of the second motor, the driving wheel is meshed with the gear turntable, a plurality of driven wheels are provided on the top cover, the driven wheels are meshed with the gear turntable, and the driving wheel and the driven wheels are both provided with a second stirring rod.

6. A method for preparing a low-density BMC molding compound as claimed in claim 5, characterized in that: A rotating disk is provided at the bottom of the first stirring rod, and a first stirring blade is provided on the rotating disk.

7. The method for preparing a low-density BMC molding compound according to claim 5, characterized in that: The second stirring rod is provided with a second stirring blade.

8. The method for preparing a low-density BMC molding compound according to claim 5, characterized in that: The bracket is provided with a fixing rod, the bracket is provided with a stirring tank body, the stirring tank body is provided with a fixing groove, and the fixing groove and the fixing rod are arranged in coordination.

9. The method for preparing a low-density BMC molding compound according to claim 4, characterized in that: The stirring speed of the disperser in step (1) or (2) is greater than 300 r / min, and the stirring speed of the bonding machine in step (3) or (4) is 28-35 r / min.

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