Preparation method of phenolic resin foam filler for oil delivery pipe, phenolic resin foam filler for oil delivery pipe and application of phenolic resin foam filler

Abstract

The invention belongs to the field of high polymer material modification, and discloses a preparation method of a phenolic resin foam filler for an oil delivery pipe, which is characterized in that a triazinyl benzoxazine monomer is added into thermoplastic phenolic resin as a curing agent, and then an inorganic filler is doped to realize modification. After modification, the phenolic resin foam filler is endowed with good fixing, supporting, heat-resisting and heat-preserving effects. The problems that due to the special configuration design of the oil conveying pipe, foaming needs to be carried out under the condition that one end is closed, and a slender closed space is not beneficial to volatilization of a solvent in thermoplastic phenolic resin; the problems that the foaming density is not uniform and the resin strength is reduced are easily caused. And meanwhile, the problems that phenolic foam materials are generally subjected to a high-temperature curing process and are insensitive to temperature intervals, and if the oil delivery pipe is of a special slender structure and is subjected to a common high-temperature curing process, the phenolic foam materials are extremely easy to spray out of the oil delivery pipe to cause large internal gaps, uneven foaming and the like are solved.

Description

Technical Field

[0001] The invention belongs to the field of polymer material modification, and particularly relates to a preparation method of a phenolic resin foam filler for an oil pipeline, the phenolic resin foam filler for an oil pipeline and applications thereof. Background Art

[0002] The oil pipeline assembly is a key component of large equipment (such as helicopters, large aircraft, etc.). The oil pipeline assembly generally includes an inner tube and an outer tube. Among them, the inner tube is the oil pipeline, which mainly serves to transport oil media; the outer tube is generally a metal tube, which can withstand a certain extrusion load during operation. In order to ensure that the inner tube of the oil pipeline is not affected when the outer tube is subjected to load extrusion, a high-strength material must be filled between the inner tube and the outer tube to play a fixed supporting role. What material to use can both play a lightweight role and play a fixed supporting role in the oil pipeline is a big problem. For this problem, foreign countries usually use high-performance phenolic foam in similar key parts.

[0003] Phenolic foam plastics not only have the same excellent thermal insulation properties as polyurethane foam materials, but also have excellent flame retardant properties, heat resistance and low toxicity that other organic thermal insulation materials do not have, making them widely used in aviation, aerospace, military ships, and thermal insulation panels. The production and preparation technology of high-performance phenolic foam in the aviation and aerospace fields is relatively mature abroad. At present, there are no phenolic foam products in China that can meet the requirements of this system. The strength, closed cell rate and thermal stability of domestic phenolic foams are difficult to meet the use requirements.

[0004] After searching, CN201910068652.1 discloses a method for preparing a benzoxazine flame retardant foaming material, comprising the following steps: (1) taking an expandable benzoxazine resin, then adding a phenolic resin in proportion, stirring and mixing evenly, and preheating at a temperature of 130 to 150°C for 15 to 40 minutes; (2) adding a chemical foaming agent, a zinc-containing nano compound, a flame retardant and a curing accelerator, stirring and mixing evenly; (3) foaming at a temperature of 160 to 180°C for 30 to 120 minutes. The present invention can reduce the curing temperature to 160°C and shorten the reaction time to 30 minutes. The obtained benzoxazine flame retardant foaming material has a foaming ratio of 3 to 11, a compressive strength of 0.7 to 1.5 MPa, a pore diameter of 80 to 480 μm, and a flame retardancy of UL94V-0. However, the strength, closed cell rate and thermal stability of this material are not suitable for use in oil pipeline components.

[0005] CN202211428716.2 discloses a benzoxazine resin system and its necessary method and a method for preparing a composite material. The raw material components of the benzoxazine resin system include benzoxazine monomers, thermosetting modifiers, diluents and inorganic filler particles, which have low viscosity, high temperature resistance, ablation resistance, and low shrinkage properties, and are suitable for composite material molding as a matrix resin. The preparation method of the benzoxazine resin system optimizes the preparation conditions so that the prepared benzoxazine resin system has excellent ablation resistance and good mechanical properties. The composite material prepared by the method for preparing a composite material has excellent compressive strength, bending strength and interlaminar shear strength. However, this scheme focuses on the improvement of ablation resistance, and does not solve the above-mentioned problem of both lightweighting and fixed support of the oil pipeline.

[0006] Therefore, it is very necessary to invent a phenolic resin foam filler product for an elongated oil pipeline to meet the use requirements in special fields. Summary of the invention

[0007] In view of the deficiencies of the above-mentioned prior art, the present invention discloses a method for preparing a phenolic resin foam filler for an oil pipeline, which solves the problem that due to the special configuration design of the oil pipeline, foaming needs to be carried out with one end closed, and the elongated closed space is not conducive to the volatilization of the solvent in the thermoplastic phenolic resin; it is very easy to cause uneven foaming density and reduced resin strength. At the same time, it solves the problem that phenolic foam materials generally use a high-temperature curing process and are insensitive to temperature ranges, while the special elongated structure of the oil pipeline, if the ordinary high-temperature curing process is used, it is very easy to spray out from the oil pipeline, resulting in large internal gaps, uneven foaming and other problems.

[0008] The preparation method of the phenolic resin foam filler for oil pipeline of the present invention uses triazine-based benzoxazine as a curing agent for the first time, and dopes inorganic filler glass microbeads into thermoplastic phenolic resin. The addition of triazine-based benzoxazine increases the maximum use temperature of the phenolic resin foam filler, and the high temperature resistance is improved; and the use of such a curing agent will not generate the volatilization of small molecular gases, thereby greatly reducing the generation of pores.

[0009] In view of the above problems, the technical solution proposed by the present invention is:

[0010] Disclosed is a method for preparing a phenolic resin foam filler for an oil pipeline. The method comprises adding a triazine-based benzoxazine monomer as a curing agent into a thermoplastic phenolic resin, and then doping with an inorganic filler to achieve modification. After the modification, the phenolic resin foam filler is endowed with good fixing support, heat resistance and heat insulation effects.

[0011] The raw materials of the present invention are added with a novel benzoxazine containing a triazine group to increase the maximum use temperature of the phenolic resin foam filler; the inorganic filler is mixed and filled into the holes of the phenolic resin foam to increase the strength and closed cell rate of the phenolic resin foam filler. The addition of triazine-based benzoxazine and glass microbeads to the thermoplastic phenolic resin for modification increases the density, elastic modulus and maximum use temperature of the phenolic resin foam filler, which can well meet the use requirements in special fields.

[0012] Furthermore, in terms of mass parts, the amount of the thermoplastic phenolic resin added is 60 parts to 80 parts, the amount of the triazine-based benzoxazine monomer added is 5 parts to 10 parts, and the amount of the inorganic filler added is 15 parts to 30 parts.

[0013] Furthermore, the structural formula of the triazine-based benzoxazine monomer is as follows:

[0014]

[0015] Further, the addition of triazine-based benzoxazine and phenolic resin mainly causes the following reactions:

[0016] Forming cross-linked bulk polymers.

[0017] Furthermore, the inorganic filler is at least one of inorganic glass and silicate. The inorganic filler is inorganic glass microbeads filled into the pores of the phenolic resin foam. The inorganic filler is mainly used to improve the hardness, strength, heat resistance, weather resistance and other properties of the material, and can also reduce production costs.

[0018] Furthermore, the inorganic glass is glass microspheres, and the size of the glass microspheres is 50 μm-200 μm. The particle size is differentiated and optimized to achieve the best filling effect.

[0019] Furthermore, the specific steps include:

[0020] S1. Material preparation: prepare thermoplastic phenolic resin and triazine-based benzoxazine monomer according to proportion, and then weigh the inorganic filler for standby use;

[0021] S2 mixing: all the materials in step S1 are placed under vacuum at a speed of 400-500rpm and stirred to mix thoroughly;

[0022] S3. Pressurized extrusion: pressurize the mixed material according to the demand, and extrude it into the oil pipeline at a pressure of 0.5MPa-0.6MPa;

[0023] S4. Curing: The phenolic resin foam filler is prepared by curing with a step curing process, and the step curing process is divided into a preheating stage, a cross-linking curing stage and a reaction stage; the preheating stage is at 40℃-60℃, and the temperature is kept for 3h-6h; the cross-linking curing stage is at 63℃-85℃, and the temperature is kept for 10h-20h. In this stage, the small molecule gas generated by the heat of the solvent contained in the thermoplastic phenolic resin is slowly volatilized to ensure the cross-linking and curing of the triazine-based benzoxazine monomer and the phenolic resin. The reaction stage is at 90℃-120℃, and the temperature is kept for 0.5h-1.5h; the degree of cross-linking between the triazine-based benzoxazine monomer and the phenolic resin is further promoted.

[0024] By gradually increasing the temperature, the curing reaction can be balanced and completely cured. First, cure at a lower temperature (slightly higher than the temperature at which the reaction can take place) for a sufficient time, and keep warm to extend the curing time. The resin system is still difficult to cure completely because the polymer is in a glassy state when the temperature is below the glass transition temperature of the resin, and it is difficult for the chain segments to move and the reaction to proceed. Therefore, it is necessary to heat it above the glass transition temperature for post-processing.

[0025] Another object of the present invention is to protect the product obtained by the preparation method of the phenolic resin foam filler for oil pipeline.

[0026] Another object of the present invention is to protect the above-mentioned phenolic resin foam filler product for oil pipelines and apply it to oil pipeline component equipment of helicopters and large aircraft.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The preparation method of the phenolic resin foam filler for oil pipeline of the present invention adds triazine-based benzoxazine to increase the maximum use temperature of the phenolic resin foam filler, and the high temperature resistance is improved; and the use of such a curing agent does not generate the volatilization of small molecular gases, which greatly reduces the generation of pores; inorganic glass microbeads are doped and filled into the pores of the phenolic resin foam, thereby improving the strength and closed-cell rate of the phenolic resin foam filler; and a special foaming stabilizer is added to ensure uniform foaming of the phenolic resin foam filler.

[0029] The preparation method of phenolic resin foam filler for oil pipelines ensures the stability of product production through reasonable adjustment of process parameters. Phenolic foaming materials generally adopt high-temperature curing process, which is insensitive to temperature range. However, due to the special slender structure of oil pipelines, if ordinary high-temperature curing process is used, it is very easy to spray out from the oil pipeline, causing large internal gaps, uneven foaming and other problems. The present invention adopts a step temperature curing process to effectively solve the problem of continuous and dense foaming of phenolic foam in slender oil pipelines.

[0030] The phenolic resin foam filler for the slender oil pipeline of the present invention can be well applied to the oil pipeline assembly of large equipment (helicopters, large aircraft, etc.), and the oil pipeline assembly filled with the phenolic resin foam filler has good fixed support, heat resistance and heat insulation capabilities. Tests show that its strength is ≥90MPa, closed cell rate is ≥90%, and thermal deformation temperature is ≥150℃, which can well meet the use requirements of the special field of fixed support, heat resistance and heat insulation, and improve the reliability of the product. DETAILED DESCRIPTION

[0031] The present invention is further described below by the following embodiments. It should be understood that the following embodiments are only used to illustrate the present invention, but not to limit the present invention.

[0032] The preparation method of the phenolic resin foam filler for oil pipeline of the present invention comprises adding a triazine-based benzoxazine monomer as a curing agent to a thermoplastic phenolic resin, and then doping an inorganic filler to achieve modification, so that the phenolic resin foam filler is endowed with good fixing support and heat-resistant and heat-insulating effects after modification. In terms of mass parts, the addition amount of the thermoplastic phenolic resin is 60 parts to 80 parts, the addition amount of the triazine-based benzoxazine monomer is 5 parts to 10 parts, and the addition amount of the inorganic filler is 15 parts to 30 parts.

[0033] The structural formula of the triazine-based benzoxazine monomer is as follows:

[0034]

[0035] The following reactions mainly occur when triazine-based benzoxazine and phenolic resin are added:

[0036] Forming cross-linked bulk polymers.

[0037] The inorganic filler is at least one of inorganic glass and silicate. The inorganic glass is glass microspheres, and the size of the glass microspheres is 50 μm-200 μm. The specific scheme is as follows.

[0038] Example 1

[0039] The preparation method of the phenolic resin foam filler for oil pipeline of this embodiment comprises the following steps:

[0040] S1. Preparation of phenolic resin materials: Mix thermoplastic phenolic resin (60% of the total mass) and triazine-based benzoxazine (10% of the total mass); weigh 30% of the total mass of inorganic glass microspheres (200 μm);

[0041] S2. Mixing: The materials are vacuumed at a pressure of -0.1 MPa and stirred at a speed of 450 rpm to mix thoroughly;

[0042] S3. Pressurized extrusion: pressurize the mixed material according to the demand, the pressure is between 0.5 and 0.6 MPa, and extrude it into the oil pipeline;

[0043] S4. The phenolic resin foam filler is prepared by curing using a step curing process. The step curing process is divided into a preheating stage, a cross-linking curing stage and a reaction stage. The preheating stage is at 45°C and kept warm for 6 hours. The overall preheating provides a sufficient basis for the subsequent reaction. The cross-linking curing stage is at 63°C-65°C and kept warm for 12 hours, slowly volatilizing the small molecule gas generated by the heat of the solvent contained in the thermoplastic phenolic resin; ensuring the cross-linking curing of the triazine-based benzoxazine monomer and the phenolic resin. The reaction stage is at 90°C-100°C and kept warm for 1 hour. Further promote the degree of cross-linking of the triazine-based benzoxazine monomer and the phenolic resin.

[0044] Tests show that the phenolic resin foam filler is uniform and dense, with a closed cell rate of 93%, an elastic modulus of up to 118MPa, and a thermal deformation temperature of 190°C.

[0045] Example 2

[0046] The preparation method of the phenolic resin foam filler for oil pipeline of this embodiment comprises the following steps:

[0047] S1. Preparation of phenolic resin materials: Mix thermoplastic phenolic resin (70% of the total mass) and triazine-based benzoxazine (8% of the total mass); weigh inorganic glass microspheres (100 μm) accounting for 22% of the total mass;

[0048] S2. Mixing: The material is vacuum (pressure -0.2MPa), and the speed is 450rpm and stirred at a uniform speed to mix thoroughly;

[0049] S3. Pressurized extrusion: pressurize the mixed material according to the demand, the pressure is between 0.5 and 0.6 MPa, and extrude it into the oil pipeline;

[0050] S4. The phenolic resin foam filler is prepared by curing using a step curing process. The step curing process is divided into a preheating stage, a cross-linking curing stage and a reaction stage; the preheating stage is at 60°C for 5 hours, the cross-linking curing stage is at 68°C-70°C for 20 hours, and the reaction stage is at 110°C-120°C for 0.5 hours.

[0051] Tests show that the phenolic resin foam filler is uniform and dense, with a closed cell rate of 92%, an elastic modulus of up to 122MPa, and a thermal deformation temperature of 190°C.

[0052] Example 3

[0053] The preparation method of the phenolic resin foam filler for oil pipeline of this embodiment comprises the following steps:

[0054] S1. Preparation of phenolic resin materials: Mix thermoplastic phenolic resin (80% of the total mass) and triazine-based benzoxazine (5% of the total mass); weigh 15% of the total mass of inorganic glass microspheres (50 μm);

[0055] S2 mixing: all materials in step S1 were placed under vacuum at a speed of 500 rpm and stirred to mix thoroughly;

[0056] S3. Pressurized extrusion: pressurize and extrude the mixed material into the oil pipeline as required; the pressure is 0.5MPa-0.6MPa and extruded into the oil pipeline;

[0057] S4. The phenolic resin foam filler is prepared by curing with a step curing process. The step curing process is divided into a preheating stage, a cross-linking curing stage and a reaction stage; the preheating stage is at 40°C-45°C, and the temperature is kept at 3h-4h, the cross-linking curing stage is at 80°C-85°C, and the temperature is kept at 10h-12h, and the reaction stage is at 100°C-110°C, and the temperature is kept at 1.5h.

[0058] Tests show that the phenolic resin foam filler is uniform and dense, with a closed cell rate of 92%, an elastic modulus of up to 136 MPa, and a thermal deformation temperature of 190°C.

[0059] Comparative Example 1

[0060] The preparation method of this comparative example comprises the following steps:

[0061] (1) Preparation of phenolic resin material: prepare thermoplastic phenolic resin; (2) vacuum high-speed stirring of the material, the stirring speed and time are the same as those in Example 2; (3) pressurizing the mixture (pressure between 0.5 and 0.6 MPa) as required and extruding it into an oil pipeline (pressure between 0.5 MPa and 0.6 MPa); (4) curing to obtain a phenolic resin foam filler using a step curing process, the curing process is the same as that in Example 2.

[0062] Tests show that the phenolic resin foam filler has large pores inside, a closed-cell rate of 62%, an elastic modulus of only 46 MPa, and a thermal deformation temperature of 110°C.

[0063] Comparative Example 2

[0064] The preparation method of this comparative example comprises the following steps:

[0065] (1) Preparation of phenolic resin materials: Mix thermoplastic phenolic resin (85% of the total mass) and triazine-based benzoxazine (15% of the total mass); (2) Mix the materials by high-speed vacuum stirring, and the stirring speed and time are the same as those in Example 2; (3) Pressurize and extrude the mixture into the oil pipeline as required (pressure is 0.5MPa-0.6MPa); (4) Use a step-curing process to cure and prepare a phenolic resin foam filler. The curing process is the same as that in Example 2.

[0066] Tests show that the phenolic resin foam filler has large pores inside, a closed-cell rate of 81%, an elastic modulus of only 79 MPa, and a thermal deformation temperature of 190°C.

[0067] Comparative Example 3

[0068] The preparation method of this comparative example comprises the following steps:

[0069] (1) Preparation of phenolic resin materials: thermoplastic phenolic resin (80% of the total mass); (2) Weighing inorganic glass microspheres (300 μm to 400 μm) accounting for 20% of the total mass; (3) Mixing the materials thoroughly by vacuum high-speed stirring; the stirring speed and time are the same as those in Example 2; (4) Pressurizing and extruding the mixed materials into the oil pipeline as required; the stirring speed and time are the same as those in Example 2; (5) Curing by step curing process to obtain phenolic resin foam filler. The curing process is the same as that in Example 2.

[0070] Tests show that the phenolic resin foam filler is uniform and dense, with a closed cell rate of 92%, an elastic modulus of only 86 MPa, and a thermal deformation temperature of 145°C.

[0071] In summary, the phenolic resin foam filler for the slender oil pipeline of the present invention can be well applied to the oil pipeline assembly of large equipment (helicopters, large aircraft, etc.), and the oil pipeline assembly filled with it has good fixed support, heat resistance and heat insulation capabilities. Tests show that its strength is ≥90MPa, closed cell rate is ≥90%, and thermal deformation temperature is ≥150℃, which can well meet the use requirements of the special field of fixed support, heat resistance and heat insulation, and improve the reliability of the product.

[0072] The above are only embodiments of the present invention. The invention is not limited to the field involved in this implementation case. The common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the content of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing a phenolic resin foam filler for an oil pipeline, characterized in that: Triazine-based benzoxazine monomer is added as a curing agent to thermoplastic phenolic resin, and then inorganic fillers are added to achieve modification. After modification, the phenolic resin foam filler is endowed with good fixing support, heat resistance and heat insulation effects.

2. The method for preparing the phenolic resin foam filler for oil pipeline according to claim 1, characterized in that: In terms of mass percentage, the amount of the thermoplastic phenolic resin added is 60 parts to 80 parts, the amount of the triazine-based benzoxazine monomer added is 5 parts to 10 parts, and the amount of the inorganic filler added is 15 parts to 30 parts.

3. The method for preparing the phenolic resin foam filler for oil pipeline according to claim 2, characterized in that: The structural formula of the triazine-based benzoxazine monomer is as follows:

4. The method for preparing the phenolic resin foam filler for oil pipeline according to claim 3, characterized in that: The following reactions mainly occur when triazine-based benzoxazine and phenolic resin are added: Forming cross-linked bulk polymers.

5. The method for preparing the phenolic resin foam filler for oil pipeline according to claim 4, characterized in that: The inorganic filler is at least one of inorganic glass and silicate.

6. The method for preparing the phenolic resin foam filler for oil pipeline according to claim 5, characterized in that: The inorganic glass is glass microbeads, and the size of the glass microbeads is 50 μm-200 μm.

7. The method for preparing the phenolic resin foam filler for oil pipeline according to claim 6, characterized in that: The specific steps include: S1. Material preparation: prepare thermoplastic phenolic resin and triazine-based benzoxazine monomer according to proportion, and then weigh the inorganic filler for standby use; S2 mixing: all the materials in step S1 are placed under vacuum at a speed of 400rpm-500rpm and stirred to mix thoroughly; S3. Pressurized extrusion: pressurize the mixed material according to the demand, and extrude it into the oil pipeline at a pressure of 0.5MPa-0.6MPa; S4. Curing: The phenolic resin foam filler is prepared by a step-curing process, and the step-curing process is divided into a preheating stage, a cross-linking curing stage and a reaction stage; the preheating stage is kept at 40℃-60℃ for 3h-6h, the cross-linking curing stage is kept at 63℃-85℃ for 10h-20h, and the reaction stage is kept at 90℃-120℃ for 0.5h-1.5h.

8. A product obtained by using the preparation method of the phenolic resin foam filler for oil pipeline according to any one of claims 1 to 7.

9. A phenolic resin foam filler product for oil pipelines as claimed in claim 8, which is used in oil pipeline assembly equipment for helicopters and large aircraft.

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