CN115746496A - Thermoplastic polyimide modified phenolic molding compound with high heat resistance and high toughness and preparation method thereof - Google Patents
Thermoplastic polyimide modified phenolic molding compound with high heat resistance and high toughness and preparation method thereof Download PDFInfo
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- CN115746496A CN115746496A CN202210816984.5A CN202210816984A CN115746496A CN 115746496 A CN115746496 A CN 115746496A CN 202210816984 A CN202210816984 A CN 202210816984A CN 115746496 A CN115746496 A CN 115746496A
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Abstract
The invention discloses a thermoplastic polyimide modified phenolic moulding plastic with high heat resistance and high toughness and a preparation method thereof, belonging to the technical field of special engineering plastics and comprising the following raw materials in parts by weight: 50 parts of linear phenolic resin, 10-20 parts of thermoplastic polyimide, 20 parts of reinforcing fiber, 10-15 parts of inorganic filler, 5 parts of curing agent and the like. Through the proportioning design, the heat resistance and toughness of the obtained molding compound are obviously improved under the condition of adding a small amount of thermoplastic polyimide, a basis is provided for solving the problem of brittle cracking of a molding compound structural member, the tolerance time of the molding compound under the extremely high temperature condition is improved, and the molding compound can be kept intact for 60 minutes at 400 ℃; the invention provides a simple preparation process and a formula with high cost performance of the phenolic molding compound, has great application potential in the fields of brake alarm systems of commercial vehicles, welding and cutting of welding guns and the like, and greatly widens the application scene of the phenolic molding compound.
Description
Technical Field
The invention relates to the technical field of special engineering plastics, in particular to a thermoplastic polyimide modified phenolic molding compound with high heat resistance and high toughness and a preparation method thereof.
Background
The phenolic resin molding compound has the characteristics of good electrical insulation performance, excellent chemical stability, higher mechanical property, good dimensional stability, good heat resistance, low molding shrinkage, moisture resistance, low toxicity, excellent processability and the like, and is widely applied to the fields of light industry, electrical industry, aerospace, machinery, building industry and the like. Phenolic molding compounds are used in the daily life of insulating structural members of electrical appliances, such as electrical switches, fuses, instrument panels, and the like. However, in some special application occasions, such as the fields of commercial vehicle brake alarm systems, welding gun welding and cutting kits, phenolic molding compounds are used as structural members, and need to work safely for a certain time at extremely high temperature (300-700 ℃) so as to ensure the safe operation of equipment. However, the temperature resistance of the phenolic molding compound on the market at present is difficult to meet the requirement. In addition, the brittleness of the phenolic molding plastic structural member can cause the risk of cracking of the thin-wall part, and further influences the service life and the reliable operation of equipment. Thus, in order to improve the use of phenolic molding compounds in more specific applications and to provide more reliable protection of device components, improvements to existing formulations are needed.
At present, the method for improving the heat resistance of the phenolic moulding compound is mainly to improve the content of fillers, such as inorganic fillers, such as talcum powder, calcium carbonate, quartz powder and the like, and organic fillers, such as cotton fiber, bamboo powder and the like, but the increase of the inorganic fillers can lead to the improvement of the brittleness of the phenolic moulding compound, and meanwhile, the improvement effect of the fillers is relatively limited. Therefore, a solution for improving the heat resistance and toughness of the molding compound is needed to solve the above problems.
Polyimide is a polymer with imide rings on the main chain, can work at 269-280 ℃, has a long service life, has a thermal decomposition temperature of 600 ℃, has high strength, high toughness, excellent chemical stability and electrical properties, and is widely applied to the fields of electronics, electrics, aerospace, new energy sources and the like. Compared with thermosetting polyimide, the thermoplastic polyimide has more excellent processing performance while ensuring excellent thermal performance, mechanical performance and electrical performance, and greatly widens the application scenes of the polyimide, so that the thermoplastic polyimide has more attention in recent years. Document 1 describes that an epoxy resin adhesive with excellent comprehensive properties is obtained by toughening and modifying an epoxy resin with thermoplastic polyimide. Document 2 describes that an epoxy adhesive is modified with a carboxyl group-containing thermoplastic polyimide. Researches find that the heat resistance and the tensile shear are obviously improved along with the increase of the content of the thermoplastic polyimide, when the content reaches 5 percent, the tensile shear strength reaches 35.9MPa, and the carbon residue rate reaches 11.4 percent, which indicates that the introduction of the thermoplastic polyimide has a relatively ideal effect.
Documents of the prior art
Document 1: maojiang, chiu Mei Fang, yu Xin Hai, etc. the development of thermoplastic polyimide toughened epoxy resin adhesive [ J ] bonding, 2010 (8): 4.
Document 2: leen, yuxin Hai, xuyongfen, et al, development of novel thermoplastic polyimide modified epoxy adhesive [ J ] bonding, 2011,32 (12): 3.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a thermoplastic polyimide modified phenolic molding compound with high heat resistance and high toughness and a preparation method thereof, and the thermoplastic polyimide modified phenolic molding compound has the advantages of high temperature resistance, high toughness and high cost performance.
In order to achieve the purpose, the invention provides a thermoplastic polyimide modified phenolic molding compound with high heat resistance and high toughness, which comprises the following components in parts by weight:
phenol novolac resin: 50 portions of
Thermoplastic polyimide: 10-20 parts of
Reinforcing fibers: 20 portions of
Inorganic filler: 10-15 parts of
Curing agent: 5 portions of
Curing accelerator: 1 part of
Plasticizer: 0.5 to 1 portion
Lubricant: 0.5-1 part.
Preferably, the thermoplastic polyimide has a weight average molecular weight of 100000 to 300000, is in the form of particles, and is crushed by a micronizer and then sieved through a 400-mesh sieve to obtain fine powder.
Preferably, the inorganic filler is a mixture of carbon black and fine silica powder or ground calcium carbonate.
Preferably, the curing agent is hexamethylenetetramine.
Preferably, the curing accelerator is calcium hydroxide.
Preferably, the lubricant is calcium stearate.
The invention has the beneficial effects that:
by adopting the technical scheme, the phenolic moulding plastic finally obtained by adopting the linear phenolic resin as the matrix resin, the adhesive and the thermoplastic polyimide as the toughening modifier has the characteristics of high toughness and high heat resistance, and has excellent product processability and good dimensional stability. In addition, the addition of a small amount of polyimide reduces the use amount of the inorganic filler, solves the problem of brittle cracking caused by excessive addition of the inorganic filler, and enables the molding compound to be suitable for application in some specific scenes under extreme environments.
In order to realize the purpose, the invention provides a preparation method of a thermoplastic polyimide modified phenolic molding compound with high heat resistance and high toughness, which comprises the following steps:
uniformly mixing phenolic resin, thermoplastic polyimide, inorganic filler, a curing agent, a curing accelerator, a lubricant and a plasticizer in parts by weight, adding the mixture into an open mill for mixing, controlling the roll temperature to be 90-100 ℃, controlling the idle roll temperature to be 140-150 ℃, starting mixing when the temperature is stable, wherein the plastication time is 3-5min, then slicing, repeatedly mixing for several times, taking out, cooling and crushing into phenolic molding plastic by using a crusher.
The invention has the beneficial effects that:
the innovation point of the invention is mainly that the high heat-resistant thermoplastic polyimide is introduced into the phenolic molding compound, and the preparation scheme of the high heat-resistant and high-toughness phenolic molding compound with high cost performance is provided. The addition of a small amount of thermoplastic polyimide can obviously improve the heat resistance and toughness of the molding compound, greatly improve the service performance of the phenolic molding compound and provide a powerful guarantee for the safe and reliable operation of equipment.
The features and advantages of the present invention will be described in detail by way of examples.
Detailed Description
In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is intended to be illustrative and not restrictive, and the scope of the invention is not to be so limited.
Example 1
The thermoplastic polyimide modified phenolic molding compound with high heat resistance and high toughness is shown in the table 1 in parts by weight.
The preparation steps are as follows: according to the table 1, phenolic resin, polyimide, treated reinforcing fiber, inorganic filler, curing agent, curing accelerator, lubricant and plasticizer in corresponding parts by weight are uniformly mixed. Setting the temperature of the open mill, wherein the temperature of an operating roller is 90 ℃, the temperature of an idle roller is 140 ℃, the distance between rollers is set to be 3mm, placing the mixture into the open mill for mixing after the temperature is stable, and repeatedly turning and fully mixing for 5min.
In the embodiment, the phenolic resin is linear phenolic resin, the polyimide is thermoplastic polyimide with the molecular weight of 100000-300000, the reinforcing fiber is glass fiber, the inorganic filler is silica powder and high-heat-resistant carbon black, the curing agent is hexamethylenetetramine, the curing agent accelerator is calcium hydroxide, the plasticizer is furfural, and the lubricant is calcium stearate.
TABLE 1 EXAMPLES 1-6
| 1 | 2 | 3 | 4 | 5 | 6 | |
| Phenol-formaldehyde novolac resin | 50 | 50 | 50 | 50 | 50 | 50 |
| Thermoplastic polyimide | 10 | 12 | 14 | 16 | 18 | 20 |
| Glass fiber | 20 | 20 | 20 | 20 | 20 | 20 |
| Silicon micropowder | 15 | 14 | 13 | 12 | 11 | 10 |
| Hexamethylenetetramine | 5 | 5 | 5 | 5 | 5 | 5 |
| Calcium hydroxide | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 |
| Furfural | 0.5 | 0.6 | 0.7 | 0.8 | 0.9 | 1.0 |
| Calcium stearate | 0.5 | 0.6 | 0.7 | 0.8 | 0.9 | 1.0 |
| Highly heat resistant carbon black | 1 | 1 | 1 | 1 | 1 | 1 |
Example 7: the difference between the thermoplastic polyimide modified phenolic molding material with high heat resistance and high toughness and the embodiment 1 is that ground calcium carbonate is used for replacing silicon micropowder.
Example 8: the difference between the thermoplastic polyimide modified phenolic molding compound with high heat resistance and high toughness and the thermoplastic polyimide modified phenolic molding compound in the embodiment 1 is that the operating roll temperature is 100 ℃, and the idle roll temperature is 150 ℃.
Comparative example 1: a phenolic molding compound differs from example 1 in that no thermoplastic polyimide is added.
The flexural strength, unnotched impact strength and heat distortion temperature of the above examples and comparative examples were measured and the results are shown in Table 2
As can be seen from the above table, the addition of the thermoplastic polyimide significantly improves the heat resistance and impact strength of the phenolic molding compound, the thermal deformation temperature of examples 1-8 under a load of 1.8MPa reaches more than 273 ℃, the bending strength reaches more than 95MPa, and the unnotched impact strength reaches more than 3.0KJ/m 2. As can be seen from example 4, the bending strength reaches up to 113MPa, the unnotched impact strength reaches up to 4.5KJ/m2, and the heat distortion temperature reaches up to 292 ℃, so the formula is the optimal solution.
The working time of the plastic structural member of the mold under extremely high temperature of the above embodiment was observed, and the change of the apparent state of the structural member under different embodiments is shown in Table 3
| 400℃@60min | 500℃@30min | 600℃@5min | |
| Example 1 | No whitening and no deformation | No whitening and no deformation | No whitening and no deformation |
| Example 2 | No whitening and no deformation | No whitening and no deformation | No whitening and no deformation |
| Example 3 | No whitening and no deformation | No whitening and no deformation | No whitening and no deformation |
| Example 4 | No whitening and no deformation | No whitening and no deformation | No whitening and no deformation |
| Example 5 | No whitening and no deformation | No whitening and no deformation | No whitening and no deformation |
| Example 6 | No whitening and no deformation | No whitening and no deformation | No whitening and no deformation |
| Example 7 | No whitening and no deformation | No whitening and no deformation | No whitening and no deformation |
| Example 8 | No whitening and no deformation | No whitening and no deformation | No whitening and no deformation |
| Comparative example 1 | With whitening and deformation | Whitening and severe deformation | Whitening and severe distortion |
As can be seen from the above table, the incorporation of a small amount of a highly heat resistant thermoplastic polyimide significantly improves the endurance time of the phenolic molding compound when operated under extremely high temperature conditions. In comparison with comparative example 1, all of the examples in which the thermoplastic polyimide was added were able to prevent any whitening and deformation from occurring at a high temperature for a certain period of time.
The thermoplastic polyimide is used as a toughening additive of the phenolic molding compound, fine powder is obtained after crushing treatment, then the fine powder is blended with other components, and finally the toughened and modified phenolic molding compound is obtained after mixing in an open mill. The thermoplastic polyimide can form a second phase in a system, but after the phenolic resin is cured, thermoplastic polyimide particles can form discontinuous and continuous interface layers with the resin, can absorb crack propagation energy, and simultaneously limit the diffusion of cracks in the interface continuous layers, and finally macroscopically shows that the toughness of the molding compound is increased.
In conclusion, the thermoplastic polyimide modified phenolic molding compound prepared by the invention has the characteristics of high toughness and high heat resistance, has higher safety coefficient compared with the traditional phenolic molding compound, provides powerful basis for the manufacturing scheme of high-temperature resistant structural members in the fields of brake alarm systems of commercial automobiles, welding and cutting of welding guns and the like, and greatly widens the application scene of the phenolic molding compound.
Claims (7)
1. The thermoplastic polyimide modified phenolic molding compound with high heat resistance and high toughness is characterized by comprising the following components in parts by weight:
phenol novolac resin: 50 portions of
Thermoplastic polyimide: 10 to 20 portions of
Reinforcing fibers: 20 portions of
Inorganic filler: 10-15 parts of
Curing agent: 5 portions of
Curing accelerator: 1 part of
Plasticizer: 0.5 to 1 portion
Lubricant: 0.5-1 part.
2. The thermoplastic polyimide modified phenolic molding compound with high heat resistance and high toughness as claimed in claim 1, wherein: the preparation method is characterized in that the weight average molecular weight of the thermoplastic polyimide is 100000-300000, the thermoplastic polyimide is granular, and fine powder is obtained after the thermoplastic polyimide is crushed by a superfine crusher and sieved by a 400-mesh screen.
3. The thermoplastic polyimide modified phenolic molding material with high heat resistance and high toughness as claimed in claim 1, wherein: the inorganic filler is a mixture of carbon black and silicon micropowder or heavy calcium carbonate.
4. The thermoplastic polyimide modified phenolic molding compound with high heat resistance and high toughness as claimed in claim 1, wherein: the curing agent is hexamethylene tetramine.
5. The thermoplastic polyimide modified phenolic molding compound with high heat resistance and high toughness as claimed in claim 1, wherein: the curing accelerator is calcium hydroxide.
6. The thermoplastic polyimide modified phenolic molding material with high heat resistance and high toughness as claimed in claim 1, wherein: the lubricant is calcium stearate.
7. The preparation method of the thermoplastic polyimide modified phenolic molding compound with high heat resistance and high toughness as claimed in any one of claims 1 to 6, characterized by comprising the following steps:
uniformly mixing the corresponding parts by weight of phenolic novolac resin, thermoplastic polyimide, inorganic filler, organic filler, curing agent, curing accelerator, lubricant and plasticizer in parts by weight, adding the mixture into an open mill for mixing, controlling the roll temperature to be 90-100 ℃, controlling the idle roll temperature to be 140-150 ℃, starting mixing when the temperature is stable, wherein the mixing time is 3-5min, then slicing, repeatedly mixing for several times, taking out, cooling, and crushing into phenolic molding compound by using a crusher.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210816984.5A CN115746496A (en) | 2022-07-12 | 2022-07-12 | Thermoplastic polyimide modified phenolic molding compound with high heat resistance and high toughness and preparation method thereof |
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|---|---|---|---|
| CN202210816984.5A CN115746496A (en) | 2022-07-12 | 2022-07-12 | Thermoplastic polyimide modified phenolic molding compound with high heat resistance and high toughness and preparation method thereof |
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