Anti-static BMC composite material and preparation method thereof

Abstract

The application relates to an anti-static BMC composite material and a preparation method thereof, and relates to the field of anti-static materials. The anti-static BMC composite material comprises the following raw materials: unsaturated resin of type 8818, PG33 low shrinkage resin, glass fiber, filler, graphite powder, carbon black powder, curing agent, polymerization inhibitor and release agent. By adding a certain amount of graphite powder and carbon black powder with conductive properties in the BMC composite material, a conductive muscle or a net-shaped passage is formed, the surface resistance of the BMC composite material is reduced, and the product has good anti-static performance. The conductive agent is prepared according to a specific proportion of graphite powder and carbon black powder. The conductive performance of graphite is better than that of carbon black powder. After the graphite is added as the main conductive agent, the surface resistance of the BMC composite material can be effectively reduced. The conductive performance of the carbon black powder is stable, and the carbon black powder is easier to disperse in the polymer base to form a stable conductive network. Therefore, on the basis of the graphite powder, a certain amount of carbon black powder is added to keep the surface resistance of the product in a stable state.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of anti-static materials, in particular to an anti-static BMC composite material and a preparation method thereof. BACKGROUND

[0002] With the rapid development of modern electronic technology, the miniaturization and complexity of internal components of electronic products are also rapidly increasing,

[0003] BMC (Bulk Molding Compound) composite material, also known as bulk molding compound, is a semi-dry process to manufacture glass fiber reinforced thermosetting products. It is a molding intermediate material made by pre-mixing unsaturated polyester resin, low shrinkage / low profile additives, initiators, internal release agents, mineral fillers, etc. into a paste, then adding thickening agents, colorants, etc. and mixing with glass fibers of different lengths in a special kettle for stirring, thickening process, and finally forming a bulk intermediate material. BMC bulk molding compound has excellent electrical properties, mechanical properties, heat resistance, and chemical corrosion resistance, and can be used for various molding processes to meet the performance requirements of various products. It has wide application in the fields of electrical appliances, motors, radios, instruments, mechanical manufacturing, chemical equipment, construction, transportation, and national defense.

[0004] Anti-static materials refer to materials that generate the least amount of electric charge when rubbed or separated from the same material or other similar materials. In the fields of semiconductor equipment and microelectronic devices, electronics, medical and food, precision instruments, and biotechnology, the surface resistance of anti-static materials is generally required to be in the range of 10 6 -10 8 Ω, while the surface resistance of the molded products of the commonly used BMC composite material in the prior art is generally not less than 10 13 Ω. Therefore, if BMC composite material is directly used in the above-mentioned fields, there are problems of poor anti-static performance and static accumulation on the surface of the product, which cannot meet the requirements of high temperature resistance and anti-static performance of the material, limiting the application of BMC composite material in the above-mentioned fields. SUMMARY

[0005] To solve the above technical problems, the present application provides an anti-static BMC composite material and a preparation method thereof, aiming to improve the anti-static performance of BMC material.

[0006] In a first aspect, the present application provides an anti-static BMC composite material, which adopts the following technical solution:

[0007] The anti-static BMC composite material comprises the following raw materials in parts by weight: 6-10 parts of unsaturated resin type 8818, 2-5 parts of PG33 low shrinkage resin, 5-10 parts of glass fiber, 15-20 parts of filler, 6-10 parts of graphite powder, 0.1-1 part of carbon black powder, 0.1-0.5 part of curing agent, 0.01-0.1 part of polymerization inhibitor and 0.1-1 part of release agent.

[0008] By adopting the technical scheme, a certain amount of graphite powder and carbon black powder with conductive performance are added to the BMC composite material, and the carbon black powder and the graphite powder can form a conductive muscle or a net-shaped passage after being dispersed in the polymer material matrix, so that the surface resistance of the BMC composite material is reduced to 10 6 -10 8 Ω, and the product has good anti-static performance. The conductive agent is prepared by mixing the graphite powder and the carbon black powder in a specific ratio, the conductive performance of the graphite is better than that of the carbon black powder, and the graphite can effectively reduce the surface resistance of the BMC composite material after being added as the main conductive agent. The carbon black powder has stable conductive performance and is easier to be dispersed in the polymer matrix to form a stable conductive network, so that the conductive performance of the BMC composite material is more stable on the basis of the graphite powder, and the surface resistance of the product is kept stable.

[0009] Optionally, the anti-static BMC composite material comprises the following raw materials in parts by weight: 6.8 parts of unsaturated resin type 8818, 3.2 parts of PG33 low shrinkage resin, 6.5 parts of glass fiber, 17.5 parts of filler, 7.5 parts of graphite powder, 0.4 part of carbon black powder, 0.15 part of curing agent, 0.025 part of polymerization inhibitor and 0.5 part of release agent.

[0010] By adopting the technical scheme, the anti-static BMC composite material prepared by matching the raw materials in the above range has the best anti-static performance, especially the graphite powder and the carbon black powder have the best conductive performance in the above adding ratio, the surface resistance of the BMC composite product can be stably kept in a specific range, and the product has long-term stable anti-static performance.

[0011] Optionally, the carbon black powder is surface-modified carbon black powder, and the surface modification process of the carbon black powder is as follows:

[0012] S1, the carbon black powder is heated and dried at 80-90 DEG C for 1-2 hours, and then saturated ammonium persulfate solution is added after cooling;

[0013] S2, aniline and dodecylbenzenesulfonic acid are dispersed in xylene to prepare a modifier;

[0014] S3, mixing the modifier and the carbon black powder system prepared in step S1, heating to 50-60℃ for 2-5h, and drying the moisture to prepare the surface modified carbon black powder.

[0015] By adopting the technical scheme, the dispersion effect of the carbon black powder in the resin matrix can be improved by modifying the surface of the carbon black powder, and the stability of the anti-static performance of the composite material is improved. Ammonium persulfate can be used as a surface oxidation treatment agent for the carbon black powder, so that a large number of oxygen-containing functional groups are generated on the surface of the carbon black powder, which is beneficial to the subsequent grafting reaction with the modifier. Meanwhile, the residual ammonium persulfate can also be used as an initiator for the modification reaction, so as to promote the reaction between the components in the initiator and the surface of the carbon black powder and form a stable surface modification structure.

[0016] Optionally, the mass ratio of the carbon black powder to the saturated ammonium persulfate solution is 1:(1.85-2.5).

[0017] By adopting the technical scheme, the mass ratio of the carbon black powder to the saturated ammonium persulfate solution is limited in the above range, so that the carbon black powder can be preliminarily surface treated, and the excess ammonium persulfate can effectively initiate the modification reaction of the subsequent modifier, so as to obtain a better modification effect.

[0018] Optionally, the length of the glass fiber is 6-12mm.

[0019] Optionally, the anti-static BMC composite material further comprises 5-8 parts of a treatment agent, and the treatment agent comprises the following raw materials in percentage by weight: water 83-92%, polyoxyethylene laurate 5-12%, and dodecyltrimethylammonium chloride 3-5%.

[0020] By adopting the technical scheme, the ether segment contained in the polyoxyethylene laurate is easy to combine with the moisture in the air through hydrogen bonding and form a conductive channel, and has a certain hygroscopicity. By being used in combination with dodecyltrimethylammonium chloride, a good anti-static effect can be achieved, and the generation of static electricity in the material friction process is reduced. In addition, the treatment agent is added after the composite material is mixed, and the active ingredients in the treatment agent are attached to the surface of the composite material by immersing the uniformly mixed composite material in the treatment agent, so as to improve the surface properties of the composite material, reduce the influence of the added graphite powder and a large amount of inorganic fillers on the compatibility of the composite material, and improve the mechanical strength of the composite material while improving the anti-static performance of the composite material after compression molding.

[0021] Optionally, the curing agent comprises one or both of tert-butyl peroxybenzoate and tert-butyl peroxy-2-ethylhexanoate.

[0022] Optionally, the polymerization inhibitor is p-benzoquinone diluted with styrene, and the concentration is 10%.

[0023] Optionally, the filler is aluminum hydroxide powder.

[0024] Optionally, the release agent is zinc stearate.

[0025] In a second aspect, the application provides a preparation method of an anti-static BMC composite material, which adopts the following technical scheme: a preparation method of an anti-static BMC composite material, comprising the following steps:

[0026] Preparation of resin paste: 8818 type unsaturated resin, PG33 low shrinkage resin, curing agent, and polymerization inhibitor are mixed to prepare a resin paste; powder material kneading: fillers, graphite powder, carbon black powder, and release agent are kneaded to obtain a powder material;

[0027] Mixing: the resin paste and the powder material are mixed, and then glass fibers are added, and an anti-static BMC composite material is obtained after mixing.

[0028] Optionally, in the mixing stage, the resin paste and the powder material are mixed by forward rotation stirring for a period of time, and then reverse rotation stirring for a period of time, so as to improve the uniformity of the mixing.

[0029] Optionally, when the treating agent is added, the following steps are included:

[0030] Preparation of resin paste: 8818 type unsaturated resin, PG33 low shrinkage resin, curing agent, and polymerization inhibitor are mixed to prepare a resin paste; powder material kneading: fillers, graphite powder, carbon black powder, and release agent are kneaded to obtain a powder material;

[0031] Mixing: the resin paste and the powder material are mixed, and then glass fibers are added, and an anti-static BMC composite material is obtained after mixing.

[0032] By adopting the above technical scheme, the mixed conductive agent composed of graphite powder and carbon black powder is first mixed and dispersed with the powder material such as fillers and release agents, and then added to the resin composition, which can improve the mixing uniformity of the powder material in the resin system. In the mixing stage, the forward stirring and then the reverse stirring can further improve the mixing uniformity. When the treating agent is added, the treating agent is sprayed on the surface of the composite material instead of the surface of the product. Compared with the traditional anti-static agent coated on the surface of the product, the treating agent in this scheme has better stability in the composite material, and can improve the forming characteristics during the compression molding of the composite material, and improve the mechanical properties of the product.

[0033] In summary, the application includes at least one of the following beneficial technical effects:

[0034] 1. In the technical solution of the present application, a certain amount of graphite powder and carbon black powder with conductive properties are added to the BMC composite material. After the carbon black powder and graphite powder are dispersed in the polymer material matrix, they can form conductive ribs or net-like pathways, reducing the surface resistance of the BMC composite material to the range of 10 6 -10 8 Ω, thereby making the product have good antistatic properties. The added conductive agent is made of graphite powder and carbon black powder in a specific ratio. The conductive performance of graphite is better than that of carbon black powder. As the main conductive agent, it can effectively reduce the surface resistance of the BMC composite material. The conductive performance of carbon black powder is stable, and it is easier to disperse in the polymer matrix to form a stable conductive network. Therefore, adding a certain amount of carbon black powder on the basis of graphite powder can make the conductive performance of the BMC composite material more stable, and the surface resistance of the product remains stable.

[0035] 2. By modifying the surface of the carbon black powder, the dispersion effect of the carbon black powder in the resin matrix can be improved, thereby improving the stability of the antistatic performance of the composite material. Ammonium persulfate can be used as a surface oxidation treatment agent for carbon black powder, which can produce a large number of oxygen-containing functional groups on the surface of carbon black powder, which is beneficial to the subsequent grafting reaction with the modifier. At the same time, the residual ammonium persulfate can also act as an initiator for the modification reaction, promoting the reaction between the components in the initiator and the surface of the carbon black powder and forming a stable surface modification structure.

[0036] 3. By limiting the mass ratio of carbon black powder to saturated ammonium persulfate solution to a specific range, the carbon black powder can be preliminarily surface treated, and the excess ammonium persulfate can effectively initiate the modification reaction of the subsequent modifier, obtaining a better modification effect. DETAILED DESCRIPTION

[0037] The present application will be further described in detail below in conjunction with specific examples. It should be noted that in the following examples, if not specified, the conditions are in accordance with the conventional conditions or the conditions recommended by the manufacturer; the raw materials used in the following examples can be obtained from ordinary commercial sources unless otherwise specified.

[0038] Preparation example of graphite powder surface modification

[0039] Preparation example 1

[0040] The graphite powder surface modification process is as follows:

[0041] S1. According to the ratio in Table 1, the graphite powder is heated to 80°C and baked for 2h. After natural cooling to room temperature, saturated ammonium persulfate is added and stirred to mix evenly;

[0042] S2. Aniline and dodecylbenzenesulfonic acid are dissolved in xylene and stirred to mix evenly to prepare the modifier;

[0043] S3, the modifier is mixed with the carbon black powder prepared in step S1, and stirred at 60°C for 4h, and then heated and dried to remove moisture to prepare a surface-modified carbon black powder.

[0044] Preparation Example 2-5

[0045] Preparation Example 2-5 is different from Preparation Example 1 in that the raw material component proportions are different, and for specific reference to Table 1, the rest are consistent with Preparation Example 1.

[0046] Table 1: Raw material component proportions (kg) of Preparation Examples 1-5

[0047]

[0048] Example 1

[0049] An antistatic BMC composite material, the raw material component proportions are referred to Table 2, and the specific preparation method is as follows:

[0050] S1, preparing a resin paste: according to the proportions in Table 2, 8818 type unsaturated resin, PG33 low shrinkage resin, curing agent, and polymerization inhibitor are mixed and then added into a dispersing agent, and dispersed at a speed of 1000r / min for 15min to prepare a resin paste;

[0051] S2, powder mixing: according to the proportions in Table 2, the filler, graphite powder, carbon black powder, and release agent are mixed and then added into a kneader and stirred for 15min to prepare a powder material;

[0052] S3, mixing: the prepared resin paste is added into a kneader, and fully stirred and kneaded for 15min, and then short-cut glass fibers with a length of 6mm are evenly scattered into the kneader, and fully stirred and kneaded for 8min, and then discharged to obtain an antistatic BMC composite material.

[0053] Among them, the carbon black powder is prepared by Preparation Example 1; the curing agent is tert-butyl benzene peroxide; the polymerization inhibitor is p-benzoquinone diluted by styrene with a concentration of 10%; the filler is aluminum hydroxide powder; and the release agent is zinc stearate.

[0054] Example 2-4

[0055] Example 2-4 is different from Example 1 in that the raw material component proportions are different, and for specific component proportions, reference is made to Table 2, and the rest are consistent with Example 1.

[0056] Table 2: Raw material component proportions (kg) of Examples 1-4

[0057]

[0058]

[0059] Comparative Example 1

[0060] The difference between this comparative example and Example 1 is that the graphite powder and carbon black powder are replaced with equal amounts of filler, while all other aspects remain the same as in Example 1.

[0061] Comparative Example 2

[0062] The difference between this comparative example and Example 1 is that an equal amount of graphite powder is used to replace carbon black powder, while all other aspects remain the same as in Example 1.

[0063] Comparative Example 3

[0064] The difference between this comparative example and Example 1 is that the graphite powder is replaced with an equal amount of carbon black powder, while all other aspects remain the same as in Example 1.

[0065] Performance testing

[0066] The obtained antistatic BMC composite material was molded into samples for performance testing. The testing items are as follows:

[0067] Antistatic properties: The surface resistance of the sample was measured using a DC voltmeter.

[0068] Mechanical properties: The tensile strength, flexural strength and impact strength of the samples were tested according to commonly used industry standards.

[0069] The performance test results of Examples 1-4 and Comparative Examples 1-3 are shown in Table 3 below.

[0070] Table 3: Performance test results of Examples 1-4 and Comparative Examples 1-3

[0071]

[0072] The data in Table 1 show that adding a certain amount of graphite powder and carbon black powder to the BMC composite matrix can effectively reduce the surface resistance of the product, giving the BMC material product good antistatic properties. The data in Comparative Examples 2 and 3 show that while adding graphite powder or carbon black powder alone as a conductive agent to the resin system can reduce the surface resistance to some extent, its effect is less than that of using graphite powder and carbon black powder in a certain proportion. This may be because the conductive network or conductive ribs formed by graphite powder or carbon black powder alone in the resin system have poor stability, thus affecting the conductivity of the material.

[0073] Example 5

[0074] The difference between this embodiment and Example 4 is that the carbon black powder was prepared by Example 2, while the rest is the same as in Example 4.

[0075] Example 6

[0076] The difference between this embodiment and embodiment 4 is that the carbon black powder is prepared from Preparation Example 3, and the rest is consistent with embodiment 4.

[0077] Embodiment 7

[0078] The difference between this embodiment and embodiment 4 is that the carbon black powder is prepared from Preparation Example 4, and the rest is consistent with embodiment 4.

[0079] Embodiment 8

[0080] The difference between this embodiment and embodiment 4 is that the carbon black powder is prepared from Preparation Example 5, and the rest is consistent with embodiment 4.

[0081] Embodiment 9

[0082] The difference between this embodiment and embodiment 4 is that the carbon black powder is not subjected to surface modification treatment, and the rest is consistent with embodiment 4.

[0083] Embodiment 10

[0084] The difference between this embodiment and embodiment 4 is that the length of the glass fiber is 12 mm, and the rest is consistent with embodiment 4.

[0085] Embodiment 11

[0086] The difference between this embodiment and embodiment 4 is that the glass fiber includes two kinds of lengths of 6 mm and 12 mm, and the mass ratio of the two is 1:1, and the rest is consistent with embodiment 4.

[0087] Embodiment 12

[0088] The raw material component ratio of this embodiment is consistent with that of embodiment 4, and the specific preparation method is as follows:

[0089] S1, preparing resin paste: according to the ratio in Table 2, 8818 type unsaturated resin, PG33 low shrinkage resin, curing agent, polymerization inhibitor are mixed and then added into the dispersing agent, and dispersed at a speed of 1000 r / min for 15 min to prepare the resin paste;

[0090] S2, powder mixing: according to the ratio in Table 2, the filler, graphite powder, carbon black powder and release agent are mixed and then added into the kneader to stir and mix for 15 min to prepare the powder material;

[0091] S3, mixing: the prepared resin paste is added into the kneader, and stirred and mixed for 10 min in the forward direction, and then stirred and mixed for 5 min in the reverse direction, and then the chopped glass fiber with a length of 6 mm is evenly scattered into the kneader, and stirred and kneaded for 8 min in the forward direction, and then discharged to obtain the anti-static BMC composite material.

[0092] The performance detection results of embodiments 5-12 are shown in Table 4 below.

[0093] Table 3: Performance test results of examples 5-12

[0094]

[0095]

[0096] As can be seen from the data in Table 3, the carbon black powder after surface modification treatment is better for improving the anti-static performance of the composite material. The reason is that the dispersion of the carbon black powder in the resin matrix is higher after surface modification treatment, and the polyaniline material formed on the surface of the carbon black powder during modification also has good conductivity, which can increase the conductivity of the carbon black powder while improving its dispersion uniformity in the resin matrix, thereby obtaining a BMC composite material with better anti-static performance. In addition, by adjusting the ratio of the modified raw materials during the modification of the carbon black powder, the modification effect can be further improved, thereby effectively improving the anti-static performance of the BMC composite material.

[0097] Example 13

[0098] The difference between this example and example 4 is that 6 kg of treating agent is also added to the BMC composite material, and the raw material ratio of the treating agent is: water 90%, polyoxyethylene laurate 6%, and dodecyltrimethylammonium chloride 4%. The polyoxyethylene laurate and dodecyltrimethylammonium chloride are uniformly dispersed in water to obtain the treating agent, and the treating agent is added by the following method:

[0099] S1, preparing resin paste: taking 8818 type unsaturated resin, PG33 low shrinkage resin, curing agent, and polymerization inhibitor, mixing them and then adding a dispersing agent, dispersing at a speed of 1000 r / min for 15 min to prepare the resin paste;

[0100] S2, powder mixing: according to the ratio in Table 2, taking the fillers, graphite powder, carbon black powder, and release agent, mixing them and then adding them to a kneader for stirring and mixing for 15 min to prepare the powder material;

[0101] S3, mixing: adding the prepared resin paste to the kneader, stirring and kneading for 15 min, then uniformly spraying the treating agent on the surface of the mixed material, and continuously stirring during the spraying process. After the spraying is completed, stand for 1 h, then remove the water by heating to obtain the anti-static BMC composite material.

[0102] Example 14

[0103] The difference between the present example and Example 13 is that the polyoxyethylene laurate is used in the treatment agent instead of the equal amount of dodecyl trimethyl ammonium chloride, and the rest is the same as Example 13.

[0104] Example 15

[0105] The difference between the present example and Example 13 is that the polyoxyethylene laurate is used in the treatment agent instead of the equal amount of dodecyl trimethyl ammonium chloride, and the rest is the same as Example 13.

[0106] The BMC composite material prepared in Examples 13-15 is molded into samples, and then the performance is detected, and the detection results are shown in Table 4 below.

[0107] Table 4: Performance detection results of Examples 13-15

[0108]

[0109] As can be seen from the data in Table 4, the use of the treatment agent further improves the anti-static performance of the BMC composite material to a certain extent, and the mechanical properties of the product are also enhanced to a certain extent, which may be because the surface of the composite material is modified by spraying the treatment agent on the surface of the composite material, so that the number of conductive channels on the surface of the composite material is increased, thereby improving the anti-static performance. In addition, after the surface performance of the BMC composite material is improved, the compatibility of the composite material is increased during the molding process, and the mechanical properties of the product are improved.

[0110] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, therefore: any equivalent changes made on the basis of the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. An antistatic BMC composite material, characterized by The raw materials include the following weight parts: 8818 type unsaturated resin 6-10 parts, PG33 low shrinkage resin 2-5 parts, glass fiber 5-10 parts, filler 15-20 parts, graphite powder 6-10 parts, carbon black powder 0.1-1 part, curing agent 0.1-0.5 part, polymerization inhibitor 0.01-0.1 part, release agent 0.1-1 part, treating agent 5-8 parts; The treating agent includes the following raw materials by weight percentage: water 83~92%, polyoxyethylene laurate 5~12%, dodecyltrimethylammonium chloride 3~5%.

2. The anti-static BMC composite material according to claim 1, characterized in that, The raw materials include the following weight parts: 8818 type unsaturated resin 6.8 parts, PG33 low shrinkage resin 3.2 parts, glass fiber 6.5 parts, filler 17.5 parts, graphite powder 7.5 parts, carbon black powder 0.4 parts, curing agent 0.15 parts, polymerization inhibitor 0.025 parts, release agent 0.5 parts.

3. The anti-static BMC composite material according to claim 1 or 2, characterized in that, The carbon black powder is a surface modified carbon black powder, and the surface modification process of the carbon black powder is as follows: S1, heat and dry the carbon black powder to 80-90℃ for 1-2h, and after cooling, add saturated ammonium persulfate solution and mix; S2, disperse aniline and dodecylbenzenesulfonic acid in xylene to obtain a modifier; S3, mix the modifier and the carbon black powder system prepared in step S1, heat to 50-60℃ for 2-5h, and after drying the moisture, obtain the surface modified carbon black powder.

4. The anti-static BMC composite material according to claim 3, characterized in that, The mass ratio of carbon black powder to saturated ammonium persulfate solution is 1:(1.85-2.5).

5. The anti-static BMC composite material according to claim 1, characterized in that, The length of the glass fiber is 6-12mm.

6. The anti-static BMC composite material according to claim 1, characterized in that, The filler is aluminum hydroxide powder.

7. The anti-static BMC composite material according to claim 1, characterized in that, The release agent is zinc stearate.

8. A method of preparing an antistatic BMC composite material according to any one of claims 1-7, characterized in that, The method includes the following steps: Preparation of resin paste: mix 8818 type unsaturated resin, PG33 low shrinkage resin, curing agent, and polymerization inhibitor to prepare resin paste; Powder material kneading: knead the filler, graphite powder, carbon black powder, and release agent to obtain powder material; Mixing: mix the resin paste and powder material, then add glass fiber, mix to obtain composite material, uniformly spray the treating agent on the composite material, then dry the moisture to obtain anti-static BMC composite material.

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