CN115742371A - Method for producing thermosetting phenolic resin-based composite material - Google Patents
Method for producing thermosetting phenolic resin-based composite material Download PDFInfo
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- CN115742371A CN115742371A CN202211120499.0A CN202211120499A CN115742371A CN 115742371 A CN115742371 A CN 115742371A CN 202211120499 A CN202211120499 A CN 202211120499A CN 115742371 A CN115742371 A CN 115742371A
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Abstract
The invention provides a method for producing thermosetting phenolic resin matrix composite materials, which uses a vacuum introduction process and adopts thermosetting phenolic resin as a resin matrix, wherein the thermosetting phenolic resin contains no more than 25 percent of organic solvent by weight ratio and has viscosity of less than 300mPa.s at introduction temperature; when the resin is cured, no acid curing agent is added, and the resin is heated and cured at a gradient temperature, wherein the introduction temperature is 15-70 ℃, and the highest curing temperature is 110-140 ℃. The invention has the advantages of simple production process, less investment, low cost, wide application range, low porosity of the prepared composite material and excellent performance.
Description
Technical Field
The invention belongs to the technical field of production of phenolic resin matrix composite materials, and relates to a method for producing a thermosetting phenolic resin matrix composite material.
Background
Phenolic resins are the earliest synthetic high molecular polymers invented in the world. The L.H. Bekland carried out systematic study on the phenolic resin and the forming process thereof in 1905-1909, and a general phenolic resin company was established in Berlin Lugus factories in 1910 to realize industrial production. Phenolic resin based composite materials also have a long history and are widely applied to the fields of fire prevention, flame retardance, insulation, ablation resistance and the like.
Phenolic resins fall into two broad categories, thermosetting and thermoplastic, of which the major ones used in continuous fiber reinforced composites are thermosetting phenolic resins. Thermosetting phenolic resins are mainly cured in two ways. One is direct heat curing, and the other is curing at a lower temperature after adding an acidic curing agent.
The thermosetting phenolic resin has high molecular weight and is in a solid or semi-solid state at normal temperature. In general, for convenience of application, a phenol resin is diluted with a solvent such as ethanol, acetone, or isopropyl alcohol to be a liquid. In preparing the composite material, the following two methods can be generally adopted:
1. the prepreg is prepared by impregnating reinforcing materials such as glass fiber, carbon fiber and the like with phenolic resin liquid containing a solvent and then naturally airing or drying. And secondly, spreading the prepreg into a mold, and curing the resin at a higher temperature (generally more than 150 ℃) by using an autoclave or a compression molding process to prepare the composite material. The composite material prepared by the method hardly contains solvent, has very low water content, and has the characteristics of low porosity, good mechanical property, ablation resistance and high carbon residue rate. However, the method has complex process and large investment in equipment and moulds, and the use scenes of the method are limited. Particularly large composite articles that exceed the size limitations of hydraulic presses and autoclave presses, cannot be made using this method.
2. Adding acidic curing agent into phenolic resin liquid containing solvent, then impregnating glass fibre and carbon fibre reinforced material, laying them on the mould, curing at lower temp. (within 100 deg.C). The composite material prepared by the method contains a large amount of unvolatile solvent and water, and has high porosity and poor mechanical property.
In addition, in some areas where cost is not a concern, there are some that use special phenolic resins to make composites by RTM processes. For example, chinese patent CN101417516 discloses a method for producing aerospace structural members by simultaneously injecting epoxy resin and phenolic resin using two RTM injection systems. Chinese patent CN101080313 discloses a method for preparing a low porosity phenolic resin based composite material using a resin transfer moulding process, which is essentially a variant of an autoclave process, the product size of which is limited by the size of the autoclave; the molding pressure is also higher and is 1.0-2.5 MPa. Chinese patent CN108407336 discloses a method for preparing a three-dimensional fabric reinforced phenolic resin matrix composite material for high-speed aircraft and spacecraft by using an RTM process, which is mainly characterized in that water generated during curing of phenolic resin is discharged by an open air exhaust method. Chinese patent CN104760303 discloses a method for preparing a solid rocket engine adiabatic diffusion section by using a modified VARTM process, which is mainly characterized in that an expandable silica gel soft mold is used. The resin used in the method is RTM barium phenolic resin produced by Beijing glass steel institute composite material Co., ltd, has the characteristic of high solid content (90.92%), and has the viscosity of 255mPa.s at 80 ℃.
The vacuum infusion process is a commonly used molding process for continuous fiber reinforced composite materials, and resin is pumped into a space between a mold and a vacuum bag by vacuum, and the fiber is infiltrated and cured to obtain the composite material. Unsaturated polyester resin, vinyl ester resin and epoxy resin are generally used in the vacuum infusion process, and the application of phenolic resin in the vacuum infusion process is not reported.
Disclosure of Invention
Aiming at the technical problems, the invention provides the method for producing the thermosetting phenolic resin-based composite material, which has the advantages of simple production process, less investment, low cost, wide application range and low porosity of the prepared composite material.
In order to achieve the technical purpose, the technical scheme adopted by the invention is as follows:
a method for producing thermosetting phenolic resin matrix composite material uses a vacuum infusion process, adopts thermosetting phenolic resin as a resin matrix, wherein the thermosetting phenolic resin contains no more than 25% by weight of organic solvent, and the viscosity of the thermosetting phenolic resin is less than 300mPa.s at the infusion temperature; when the resin is cured, no acid curing agent is added, and the resin is heated and cured at a gradient temperature, wherein the introduction temperature is 15-70 ℃, and the highest section curing temperature is 110-140 ℃.
The acidic curing agent is an acidic substance which is added into the phenolic resin and can reduce the curing temperature of the phenolic resin.
Preferably, the thermosetting phenolic resin is a phenolic resin which is synthesized by catalysis of an alkaline catalyst, has a phenolic molar ratio of 1.
Preferably, the vacuum introduction process comprises: lay 1 resin pipe, 1 exhaust tube and 1 at least reserve exhaust tube respectively in reinforcing material's both sides, the exhaust tube is connected to the vacuum pump, ties up resin pipe and reserve exhaust tube, makes it sealed airtight, opens the vacuum pump, through the exhaust tube evacuation, after the exhaust tube is blockked up by the resin, switches over into reserve exhaust tube in proper order, makes the vacuum can last.
Preferably, the step temperature heat curing means that: after the resin is introduced, gradually and slowly raising the temperature from the introduction temperature to 110-140 ℃ in a drying room, an oven or a mould heating mode, wherein the temperature raising time is not less than 2 hours.
More preferably, the step temperature heating curing further comprises demolding after heat preservation at 110-140 ℃ for 1-2 hours.
Preferably, the porosity of the composite material < =20%.
Preferably, the composite material comprises fiber-reinforced phenolic resin such as glass fiber (containing quartz fiber and high silica fiber), carbon fiber, ceramic fiber, basalt fiber, boron carbide fiber, silicon carbide fiber and aramid fiber.
The beneficial effects of the invention are as follows:
the method for producing the thermosetting phenolic resin-based composite material by using the vacuum infusion process changes the traditional cognition that phenolic resin is not suitable for the vacuum infusion process in the field, and has the advantages of simple production process, less investment, low cost, wide application range, low porosity of the prepared composite material and excellent performance.
Detailed Description
In order to more clearly illustrate the present invention, the present invention will be described in further detail with reference to examples. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.
The vacuum leading-in forming process is a new forming process developed in the industry within 20 years, and the basic method is that firstly, a reinforcing material is paved on a mould, then a vacuum bag film is paved, and vacuum is pumped by a vacuum pump, so that vacuum is formed between the mould and the vacuum bag film. Finally, under the action of vacuum, after the resin matrix is sucked between the mould and the vacuum bag to be impregnated with the reinforcing material, the resin is cured at normal temperature or under the heating condition, and finally the composite material is formed by demoulding, wherein unsaturated polyester resin, vinyl ester resin and epoxy resin are mainly used.
Phenolic resins are generally considered by the art to be unsuitable for use in vacuum infusion processes. The inventor of the application finds in research and practice that the vacuum infusion process can be used for producing the phenolic resin matrix composite material as long as the reaction temperature, the reaction speed, the reaction degree and the process control parameters of the phenolic resin are well matched, so that the reaction speed of the resin is slow in early air exhaust, and the solvent and the water are not boiled when the resin starts to gel.
The thermosetting phenolic resin adopted in the invention can be used for producing the thermosetting phenolic resin-based composite material in the invention as long as the thermosetting phenolic resin contains no more than 25% by weight of organic solvent (solid content > = 75%) and has viscosity of less than 300mPa.s at the introduction temperature (preferably 25-65 ℃); the phenolic resin can be synthesized by using an alkaline catalyst, has a phenolic molar ratio of 1.2-1. The thermosetting phenolic resin has the characteristics of low solvent content, low viscosity, high reaction speed and low curing temperature. Of course, in addition to the several thermosetting phenol resins listed in the following examples, it is possible to select from other commercially available products satisfying the above conditions.
In the following examples, the ordinary temperature means 25 ℃.
Example 1
The mould was cleaned and coated with a release agent and then 27 layers of 300 x 300mm 018 glass fibre scrim (weight 318 g) were laid on the mould; then lay 1 layer of demoulding cloth, lay vacuum bag film and seal with sealing rubber strip. Lay 1 resin pipe, 1 exhaust tube and 1 reserve exhaust tube respectively in reinforcing material's both sides, exhaust tube and reserve exhaust tube are connected to the vacuum pump through the buffer tank. And (3) tightening the resin pipe and the spare exhaust pipe to seal the resin pipe and the spare exhaust pipe without air leakage, starting the vacuum pump, and vacuumizing through the exhaust pipe.
Barium-phenolic resin (purchased from Beijing glass Steel institute composite Co., ltd., solid content > =85%, viscosity at 25 ℃ is 55. + -. 10 mPa.s) was used for introduction at normal temperature. The resin tube is dipped into the resin and the tie is released, allowing the resin to be drawn through the resin tube. When the resin is completely soaked in the reinforcing material, the resin pipe is tightened again without air leakage.
And continuously opening the vacuum, putting the mould into an oven, gradually increasing the temperature of the oven from the normal temperature to 130 ℃ after 5 hours, preserving the heat at 130 ℃ for 2 hours, taking out the mould from the oven after the resin is completely cured, and demoulding to obtain the glass fiber reinforced phenolic resin matrix composite plate.
In the above process, after the exhaust tube is blocked by the resin to be exhausted, the standby exhaust tube is opened to continue the vacuum.
The composite panels were tested for flexural strength, apparent density and porosity.
Example 2
The mould was cleaned and coated with a release agent and then 6 layers of 300 x 300mm 600g/m were applied to the mould 2 Glass fiber biaxial cloth (weight 372 g); then lay 1 layer of demoulding cloth, lay vacuum bag film and seal with sealing rubber strip. Lay 1 resin pipe, 1 exhaust tube and 1 reserve exhaust tube respectively in reinforcing material's both sides, exhaust tube and reserve exhaust tube are connected to the vacuum pump through the buffer tank. And (4) tightly binding the resin pipe and the spare exhaust pipe to seal the resin pipe and the spare exhaust pipe without air leakage, starting the vacuum pump, and vacuumizing through the exhaust pipe.
616 ammonia phenolic resin (purchased from Beijing glass Steel institute composite materials Co., ltd., solid content > =90%, viscosity at 25 ℃ is 150 +/-30mPa.s) is used for introduction at normal temperature. The resin tube is dipped into the resin and the tie is released, allowing the resin to be drawn through the resin tube. When the resin is completely soaked in the reinforcing material, the resin pipe is tightened again without air leakage.
And continuously opening the vacuum, putting the mold into an oven, gradually increasing the temperature of the oven from the normal temperature to 130 ℃ after 4 hours, preserving the heat at 130 ℃ for 2 hours, taking out the mold from the oven after the resin is completely cured, and demolding to obtain the glass fiber reinforced phenolic resin matrix composite plate.
In the above process, after the exhaust tube is blocked by the resin to be exhausted, the standby exhaust tube is opened to continue the vacuum.
The composite panels were tested for flexural strength, apparent density and porosity.
Example 3
The mould was cleaned and coated with a release agent and then 27 layers of 300 x 300mm 018 glass fibre scrim (weight 318 g) were laid on the mould; then 1 layer of demoulding cloth is laid, and finally a vacuum bag film is laid and sealed by a sealing rubber strip. Lay 1 resin pipe, 1 exhaust tube and 1 reserve exhaust tube respectively in reinforcing material's both sides, exhaust tube and reserve exhaust tube are connected to the vacuum pump through the buffer tank. And (4) tightly binding the resin pipe and the spare exhaust pipe to seal the resin pipe and the spare exhaust pipe without air leakage, starting the vacuum pump, and vacuumizing through the exhaust pipe.
GP-652D79 phenolic resin (purchased from Korea chemical Co., ltd., solid content of 75-79%, viscosity of 1700-2500mPa.s at 25 ℃ and viscosity of 200-300mPa.s after heating to 50 ℃ as general-purpose resin for pultrusion process) is preheated to 50 +/-5 ℃, a resin pipe is immersed into the resin, and the ribbon is released to ensure that the resin is sucked in through the resin pipe. When the resin is completely soaked in the reinforcing material, the resin pipe is tightened again without air leakage.
And continuously opening the vacuum, putting the mould into an oven, gradually increasing the temperature of the oven from 50 ℃ to 140 ℃ after 5 hours, preserving the heat at 140 ℃ for 2 hours, taking out the mould from the oven after the resin is completely cured, and demoulding to obtain the glass fiber reinforced phenolic resin matrix composite plate.
In the above process, after the exhaust tube is blocked by the resin to be exhausted, the standby exhaust tube is opened to continue the vacuum.
The composite panels described above were tested for flexural strength, apparent density and porosity.
Example 4
The mould was cleaned and coated with a release agent and then 27 layers of 300 x 300mm 018 glass fibre scrim (weight 318 g) were laid on the mould; then 1 layer of demoulding cloth is laid, and finally a vacuum bag film is laid and sealed by a sealing rubber strip. Lay 1 resin pipe, 1 exhaust tube and 1 reserve exhaust tube respectively in reinforcing material's both sides, exhaust tube and reserve exhaust tube are connected to the vacuum pump through the buffer tank. And (4) tightly binding the resin pipe and the spare exhaust pipe to seal the resin pipe and the spare exhaust pipe without air leakage, starting the vacuum pump, and vacuumizing through the exhaust pipe.
BST-PF23 phenolic resin (also known as PF23 solventless phenolic resin) was preheated to 65 + -5 deg.C, the resin tube was dipped into the resin, and the tie was released, allowing the resin to be drawn through the resin tube. When the resin is completely soaked in the reinforcing material, the resin tube is tightened again without air leakage.
The BST-PF23 phenolic resin is solvent-free thermosetting phenolic resin synthesized by taking phenol and formaldehyde as raw materials, and the production method comprises the following steps:
putting phenol and formaldehyde into a reaction kettle according to the proportion of 1mol. Heating to 60-70 deg.c, and stopping heating after the reaction begins to release heat. The kettle temperature was gradually raised to 95 ℃ by self-exotherm with incubation (temperature controlled not to boil) and then continuous sampling was used to test the free aldehyde content. When the content of free aldehyde is less than 0.5%, cooling to 60-65 ℃, and carrying out reduced pressure distillation and dehydration. When the dehydration amount reaches a theoretical value, the distillation is stopped, and the materials are discharged after sampling and analysis are qualified.
The technical parameters of the BST-PF23 phenolic resin obtained by the method are as follows:
TABLE 1 technical parameters of BST-PF23 phenolic resin products
| Appearance (visual inspection) | Brownish yellow transparent liquid |
| Viscosity (mPa. S,25 ℃ C.) | 2000-4000 |
| Viscosity (mPa. S,65 ℃ C.) | 200-300 |
| Density (g/cm 3, 25 ℃ C.) | 1.0-1.1 |
| Solid content (80 ℃ for 2 h) | 87-92％ |
| Residual carbon Rate (TGA, 800 ℃ C.) | 68-72％ |
And continuously opening the vacuum, putting the mold into an oven, gradually raising the temperature of the oven from 65 ℃ to 110 ℃ after 4 hours, preserving the heat at 110 ℃ for 2 hours, taking out the mold from the oven after the resin is completely cured, and demolding to obtain the glass fiber reinforced phenolic resin matrix composite plate.
In the above process, after the exhaust tube is blocked by the resin to be exhausted, the standby exhaust tube is opened to continue the vacuum.
The composite panels described above were tested for flexural strength, apparent density and porosity.
The test results of examples 1-4 are shown in Table 2.
TABLE 2 test results for examples 1-4
| Item | Example 1 | Example 2 | Example 3 | Example 4 |
| Flexural Strength (MPa) | 354 | 372 | 326 | 419 |
| Weight of fiber (g) | 318 | 372 | 318 | 318 |
| Template thickness (mm) | 3.7 | 3.7 | 3.7 | 3.7 |
| Sample weight (g) | 501 | 512 | 482 | 522 |
| Apparent density (g/cm ^ 3) | 1.50 | 1.54 | 1.45 | 1.57 |
| Porosity (%) | 14.6 | 11.7 | 19.6 | 9.1 |
It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all the embodiments of the present invention are not exhaustive, and all the obvious variations or modifications which are introduced in the technical scheme of the present invention are within the scope of the present invention.
Claims (8)
1. A method for producing a thermosetting phenol-formaldehyde resin-based composite material, characterized in that a vacuum infusion process is used, a thermosetting phenol-formaldehyde resin is used as a resin matrix, the thermosetting phenol-formaldehyde resin contains not more than 25% by weight of an organic solvent, and the viscosity at the infusion temperature is less than 300mPa.s; when the resin is cured, no acid curing agent is added, and the resin is heated and cured at a gradient temperature, wherein the introduction temperature is 15-70 ℃, and the highest section curing temperature is 110-140 ℃.
2. The method for producing the thermosetting phenolic resin-based composite material as claimed in claim 1, wherein the thermosetting phenolic resin is a phenolic resin which is catalytically synthesized by using an alkaline catalyst, has a phenolic molar ratio of 1.2-1, can be gelled at 80-100 ℃ and can be cross-linked and cured at 110-140 ℃.
3. The method of producing a thermosetting phenolic resin based composite material according to claim 1, characterised in that the vacuum infusion process comprises: lay 1 resin pipe, 1 exhaust tube and 1 at least reserve exhaust tube respectively in reinforcing material's both sides, the exhaust tube is connected to the vacuum pump, ties up resin pipe and reserve exhaust tube, makes it sealed airtight, opens the vacuum pump, through the exhaust tube evacuation, after the exhaust tube is blockked up by the resin, switches over reserve exhaust tube evacuation in proper order, makes the vacuum can last.
4. The method for producing thermosetting phenolic resin-based composite material according to claim 1, wherein the step temperature heat curing means that: after the resin is introduced, the temperature is gradually and slowly increased to 110-140 ℃ from the introduction temperature in a heating mode of a drying room, an oven or a mould, and the temperature-increasing time is not less than 2 hours.
5. The method for producing thermosetting phenolic resin-based composite material according to claim 4, wherein the step temperature heat curing further comprises demoulding after 1-2 hours of heat preservation at 110-140 ℃.
6. The method of producing a thermosetting phenolic resin-based composite material according to claim 1, characterised in that the porosity of the composite material < =20%.
7. The method of producing a thermosetting phenolic resin based composite material according to claim 1 or 6 characterised in that the composite material comprises glass fibres, carbon fibres, ceramic fibres, basalt fibres, boron carbide fibres, silicon carbide fibres, aramid fibre reinforced phenolic resin.
8. The method of producing a thermosetting phenolic resin based composite material according to claim 7 wherein the glass fibres comprise quartz fibres and high silica fibres.
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