阅读说明：本技术 一种超轻耐高温蜂窝芯材及其制备方法 (Ultra-light high-temperature-resistant honeycomb core material and preparation method thereof ) 是由 赵伟栋 赵培晔 张东霞 樊孟金 张云鹭 崔超 陈薇 潘玲英 王保林 赵云峰 王爽 于 2020-04-30 设计创作，主要内容包括：本发明提供了一种超轻耐高温蜂窝芯材及其制备方法,包括芯条胶印制：在料块上印制芯条胶,相邻两条芯条胶之间的宽度为印制的芯条胶宽度的三倍,铺叠料块,上下相邻两层料块中芯条胶间隔相等且等于芯条胶宽度,制得未固化蜂窝叠块；芯条胶固化；蜂窝拉伸：将经过加压固化处理的蜂窝叠块进行拉伸,直到蜂窝孔格拉伸至正六边形状态；浸渍胶液：将拉伸后的蜂窝块在浸胶槽中浸渍耐高温浸渍胶；浸渍胶的固化：在设定温度下固化耐高温浸渍胶,固化完成后得到蜂窝芯材。本发明可以适用于边长低至2.00～11.00mm,公称密度低至49～110Kg/m<Sup>3</Sup>蜂窝芯材的制备,赋予蜂窝以优异的抗压性能和抗剪切性能,实现300℃高温下的长时稳定工作。(The invention provides an ultralight high-temperature-resistant honeycomb core material and a preparation method thereof, wherein the preparation method comprises the following steps of core strip offset printing: printing core strip glue on the material blocks, wherein the width between two adjacent core strip glue is three times of the width of the printed core strip glue, paving the material blocks, and making the interval between the core strip glue in two adjacent material blocks equal and equal to the width of the core strip glue to obtain an uncured honeycomb laminated block; curing the core strip glue; honeycomb stretching: stretching the honeycomb stacked block subjected to the pressure curing treatment until the honeycomb cells are stretched to a regular hexagon state; dipping glue solution: dipping the stretched honeycomb block in a dipping tank with high-temperature-resistant dipping glue; curing the impregnating adhesive: and curing the high-temperature-resistant impregnating adhesive at a set temperature to obtain the honeycomb core material after curing is finished. The invention can be applied to the side length of 2.00-11.00 mm and the nominal density of 49-110 Kg/m 3 The preparation of the honeycomb core material endows the honeycomb with excellent compression resistance and shear resistance, and realizes long-term stable work at the high temperature of 300 ℃.)

1. The preparation method of the ultralight high-temperature-resistant honeycomb core material is characterized by comprising the following steps of:

step 1, core strip offset printing: printing core strip glue on the material blocks, wherein the width between two adjacent core strip glue is three times of the width of the printed core strip glue, paving the material blocks, and making the interval between the core strip glue in two adjacent material blocks equal and equal to the width of the core strip glue to obtain an uncured honeycomb laminated block;

step 2, curing the core strip glue: heating, pressurizing and curing the core strip glue of the honeycomb laminated block;

step 3, honeycomb stretching: stretching the honeycomb stacked block subjected to the pressure curing treatment until the honeycomb cells are stretched to a regular hexagon state;

step 4, dipping glue solution: dipping the stretched honeycomb laminated block in a dipping tank with high-temperature-resistant dipping glue;

and 5, curing the impregnating adhesive: and curing the high-temperature-resistant impregnating adhesive at a set temperature to obtain the honeycomb core material after curing is finished.

2. The method of claim 1, further comprising pre-treating the log material prior to printing the core rod gum on the log, the pre-treating comprising the steps of:

the polyimide acid resin is adjusted to have the viscosity of 50-200 cP through a solvent, the polyimide acid resin and the material block are uniformly coated on the material block by adopting a tape casting method according to the mass percentage of 1-6 wt% of the polyimide acid resin and the material block, and the polyimide acid resin is dried at the temperature of 100-150 ℃.

3. The preparation method according to claim 1, wherein in the step 1, the material of the block is selected from any one or more of alkali-free glass cloth, electronic glass cloth, poly-p-phenyl-benzo-dioxazole fabric or non-woven fabric, polyimide fabric or non-woven fabric, carbon cloth and quartz cloth; and/or

The thickness of the material block is less than or equal to 0.2mm, and the material block can resist temperature more than or equal to 300 ℃.

4. The method of claim 3, wherein when the panel is a fiber fabric, the texture of the fiber fabric includes any one or more of 0 °/90 °, ± 30 °, ± 45 ° or ± 60 °.

5. The method of claim 4, wherein the weave of the fiber fabric is selected from the group consisting of 0 °/90 ° and ± 45 ° weaves.

6. The method of claim 5, wherein the stacking of two adjacent honeycomb blocks comprises: (1)0 °/90 ° and ± 45 ° are alternately laminated; (2) two layers of the layers are alternately laminated at 0 degree/90 degrees and one layer of the layers is +/-45 degrees; (3) one layer of the film is 0 degree/90 degree and two layers of the film are plus or minus 45 degrees and are alternately laminated.

7. The preparation method according to claim 1, wherein in the step 1, the printed core stripe glue can be solid core-shaped or non-solid core-shaped including twill-shaped, net-shaped and round hole-shaped.

8. The preparation method according to claim 1, wherein in the step 1, the core bar glue is prepared from the following components in parts by mass:

wherein the active modifier is selected from any one or more of alkynyl benzoxazine resin, phenolic cyanate resin or bismaleimide resin.

9. The method according to claim 8, wherein the polyimide resin is selected from thermosetting polyimide resins synthesized by PMR method, alkynyl terminated or norbornene terminated; and/or

The thermoplastic resin is selected from one or more of polyarylethersulfone resin, polyamide-imide resin or polyimide resin; and/or

The inorganic nano particles are selected from any one or more of nano silicon dioxide, nano titanium dioxide or micro nano graphite powder; and/or

The solvent is selected from one or more of acetone, butanone, cyclohexane, tetrahydrofuran, diethylene glycol dimethyl ether, N' -dimethylacetamide and N-methylpyrrolidone.

10. The method of claim 8, wherein the core rod glue is prepared by a method comprising the steps of:

step 1, adding 1/4-1/3 thermoplastic resin into an active modifier, dissolving at 100-150 ℃, cooling to below 80 ℃, adding the rest thermoplastic resin and inorganic nanoparticles into the active modifier, and stirring and dispersing to obtain a component A;

and 2, under the condition of stirring at room temperature, adding the polyimide resin and the component A into a solvent for dissolving and dispersing to obtain uniform and stable honeycomb core strip glue.

11. The method according to claim 1, wherein in step 1, the width of the core rod rubber is 2.00mm to 11.00 mm.

12. The preparation method according to claim 1, wherein in the step 2, the curing pressure is 0.5-1.0 MPa, the curing temperature is 200-350 ℃, and the temperature is kept for 2-6 h.

13. The method according to claim 1, wherein in step 4, the high temperature resistant impregnating compound is selected from one or more of a PMR type polyimide resin or a polyimide acid resin, wherein the PMR type polyimide resin comprises a norbornene end-capping type, an ethynyl end-capping type, a phenylethynyl end-capping type, and a bismaleimide end-capping type.

14. The preparation method of claim 1, wherein in the step 5, the curing temperature of the high-temperature impregnating adhesive is 200-350 ℃, and the curing time is 2-6 h.

15. An ultra-light high temperature resistant honeycomb core material prepared by the preparation method of any one of claims 1 to 14.

Technical Field

The invention belongs to the technical field of honeycomb preparation, and relates to an ultralight high-temperature-resistant honeycomb core material and a preparation method thereof.

Background

With the development of the spacecraft technology, particularly in the field of hypersonic vehicles represented by strategic tactical missiles, new requirements are put forward on various high-performance materials. As the flying Mach number of the aircraft is further improved, the surface temperature of structural layers of corresponding components such as an air rudder, a resistance plate and the like reaches more than 300 ℃. The honeycomb sandwich structure material is an efficient material with light weight, high specific strength and high specific rigidity, can be used for manufacturing structural members and functional members for heat insulation, noise reduction and the like, and is one of main materials for manufacturing advanced aircrafts in the future. In the existing various honeycombs, only laser welding titanium alloy honeycombs and high-temperature alloy steel honeycombs can meet the temperature resistance requirement, but the metal honeycombs have larger volume weight; the polymer-based honeycomb with low volume weight, such as Nomex honeycomb, has the serious problem that the mechanical properties of a matrix and a core strip adhesive are greatly attenuated at 300 ℃, so that the temperature resistance grade of the honeycomb material is urgently needed to be improved, and the technical blank of the light honeycomb core material which can resist the high temperature of 300 ℃ in China is filled.

In addition, the temperature resistance level of the existing glass cloth honeycomb is lower than 200 ℃, the side length of the honeycomb is more than 5mm, the cells are large, the high-performance small-side-length small-cell high-temperature resistant honeycomb with the size of 2.75mm is lacked, and the compression resistance and the shearing performance of the honeycomb are required to be further improved. And moreover, the printing of the honeycomb core strip glue is divided into automatic glue spreader glue printing and common manual glue printing. The core strip glue obtained by glue printing of the automatic glue spreader is high in glue printing efficiency, uniform in glue printing, regular in prepared honeycomb, high in equipment cost and suitable for continuous production requirements of mass single-variety honeycombs. The common manual glue printing method is relatively rough, and relatively poor in glue printing uniformity and regularity, but the traditional common manual method has the defects of inaccurate honeycomb laminated positioning, poor honeycomb regularity, high labor intensity, low preparation efficiency and the like, and cannot meet the requirements of aerospace on multiple varieties, small batch, high quality and high performance.

Disclosure of Invention

In order to overcome the defects of the prior art, the inventor carries out intensive research and provides the ultralight high-temperature-resistant honeycomb core material and the preparation method thereof, the pretreatment process of the material block is adopted, the permeability and the diffusion effect of the core strip glue are controlled, and the permeation of the core strip glue to the back of the glass cloth and the expansion of the core strip glue in the width direction are improved; the core bar glue is printed by adopting the screen printing process with double screen printing plates and an automatic positioning function, the problems of poor cellular regularity caused by uniform glue saving and poor glue thickness and inaccurate lamination positioning by a visual method in the traditional manual glue printing method are solved, and the high quality of the honeycomb is ensured. The fabric weave structures of 0 degree/90 degrees, 30 degrees, 45 degrees, 60 degrees and the like are adopted, and simultaneously, the material blocks with different weave structures are alternately laminated according to a set rule, so that the compression resistance of the honeycomb is endowed, and the shearing strength of the honeycomb is improved. The invention also has the advantages of low cost, suitability for various honeycombs, small batch and high performance honeycombs, and can meet the high requirements in high-tech fields such as aerospace, and the like, thereby completing the invention.

The invention aims to provide the following technical scheme:

in a first aspect, a preparation method of an ultralight high-temperature-resistant honeycomb core material comprises the following steps:

step 1, core strip offset printing: printing core strip glue on the material blocks, wherein the width between two adjacent core strip glue is three times of the width of the printed core strip glue, paving the material blocks, and making the interval between the core strip glue in two adjacent material blocks equal and equal to the width of the core strip glue to obtain an uncured honeycomb laminated block;

step 2, curing the core strip glue: heating, pressurizing and curing the core strip glue of the honeycomb laminated block;

step 3, honeycomb stretching: stretching the honeycomb stacked block subjected to the pressure curing treatment until the honeycomb cells are stretched to a regular hexagon state;

step 4, dipping glue solution: dipping the stretched honeycomb laminated block in a dipping tank with high-temperature-resistant dipping glue;

and 5, curing the impregnating adhesive: and curing the high-temperature-resistant impregnating adhesive at a set temperature to obtain the honeycomb core material after curing is finished.

In a second aspect, the ultralight high-temperature-resistant honeycomb core material is prepared by the preparation method of the first aspect.

The ultralight high-temperature-resistant honeycomb core material and the preparation method thereof provided by the invention bring beneficial technical effects:

(1) the invention can be applied to the side length of 2.00-11.00 mm and the nominal density of 49-110 Kg/m³When the ultra-thin high temperature resistant glass cloth is adopted, the honeycomb core material can be prepared into the honeycomb core material with the side length as low as 2.00mm and the nominal density as low as 49Kg/m³The small-cell honeycomb core material can resist the high temperature of 300 ℃ for a long time and greatly reduce the weight, has excellent compression resistance and shear resistance, and fills the gap of the domestic preparation technology of the light high-temperature-resistant honeycomb core material.

(2) The invention realizes the continuous mechanical pretreatment technology of the fabric by using the spreading machine and adopting the tape casting method, and is beneficial to solving the difficult problems of thickness direction permeation and edge diffusion in the core strip offset printing process.

(3) The invention adopts the screen printing process to realize the printing of the core strip glue for the first time, overcomes the process problems of difficult control of glue printing amount, poor glue printing uniformity and the like in the traditional manual printing such as kraft paper printing and the like, and has the advantages of high honeycomb regularity, uniform bonding and high strength of honeycomb nodes, simple and convenient operation and great reduction of labor and equipment cost.

(4) The self-made high-performance polyimide core strip adhesive is adopted, the prepared honeycomb is stable in node at the high temperature of 300 ℃, and the mechanical strength retention rate can reach more than 70%.

(5) The curing temperature of the polyimide resin with the glass transition temperature Tg of more than 300 ℃ is generally more than 300 ℃, the initial curing temperature of the core strip adhesive is reduced by adding the active modifier, so that the core strip adhesive is partially cured at the temperature of below 250 ℃ to meet the requirement of honeycomb node strength, and then the core strip adhesive is further cured along with the curing of the honeycomb impregnating adhesive to achieve the purpose of fully curing and improving the honeycomb node strength. The step curing characteristic can obtain good manufacturability, reduce energy consumption and improve preparation efficiency.

(6) The invention utilizes the characteristics of the thermoplastic resin particles that are insoluble at normal temperature and soluble at high temperature in the active modifier to control the rheological characteristic of the core strip glue. Firstly, the thermoplastic resin is insoluble at normal temperature, the addition amount of the thermoplastic resin can be obviously increased to solve the wire drawing phenomenon caused by the dissolution of the thermoplastic resin, and the improvement of the gluing quality of the core strip glue is facilitated. Secondly, the thermoplastic resin is dissolved in the heating and curing process, the viscosity of the core strip glue is greatly improved, the glue penetration phenomenon of the core strip glue to the back of the glass cloth substrate under the action of curing pressure is avoided, the toughness of the high-temperature-resistant core strip glue can be obviously improved, and the strength of the honeycomb node is improved.

(7) The invention uses inorganic nano particles and granular thermoplastic resin particles as thixotropic agents to change the fluid characteristics of the core strip glue, so that the core strip glue conforms to the characteristics of a pseudoplastic fluid, the viscosity of the core strip glue in the state is higher when the core strip glue is not stressed, the permeation phenomenon of the core strip glue to the back of glass cloth when the nodes are glued can be improved, and the quality of the honeycomb is improved.

(8) The invention selects 1/4-1/3 parts of thermoplastic resin to be dissolved in the active modifier at high temperature in advance, which ensures that the prepared core bar glue has certain viscosity and prevents the residual thermoplastic resin particles and inorganic nano particles which are added subsequently from settling in the core bar glue solution. In addition, the thermoplastic resin particles and the inorganic nanoparticles have proper particle sizes, the stability of the particles in a solution is also improved, and the core-strip glue prepared by the method has no solid precipitation and precipitation.

(9) The thermoplastic resin particles in the core strip glue are not required to be dissolved in the solvent, so that a large amount of high-boiling-point polar solvent is not required, the core strip glue can be dissolved in a common solvent, the selection range of the solvent is widened, and the environment-friendly requirement is favorably met.

(10) The temperature-resistant grades of the selected main resin, the active modifier, the thermoplastic resin and the inorganic nanoparticles are all higher than 300 ℃, so that the heat resistance of the whole core strip adhesive is ensured, and the strength of a honeycomb node at 300 ℃ is more than or equal to 3N/cm. In addition, the core strip glue has high room temperature viscosity and no wire drawing phenomenon, when a honeycomb laminated block is prepared, glass cloth at a node has no glue penetration phenomenon, the honeycomb is regular and has good quality, and the node strength of the room temperature honeycomb is more than or equal to 5N/cm. The core strip adhesive and the preparation method are not only suitable for ultrathin glass cloth honeycombs, but also have important popularization values for other types of glass cloth and paper honeycombs.

(11) According to the honeycomb core stretching-impregnating-curing integrated device, the honeycomb stretching machine frame and the impregnation tank are integrally designed, so that honeycomb stretching and impregnation are synchronously performed, and the working efficiency is effectively improved; after the impregnation tank is separated from the stretching machine frame, the stretching machine frame can be directly moved into a high-temperature oven for honeycomb curing and shaping, and the device realizes the multifunctional integration of honeycomb core stretching, honeycomb impregnation and impregnation adhesive curing.

(12) According to the honeycomb core stretching-impregnating-curing integrated device, the ball screw and the guide rail are preferably made of stainless steel materials with high strength, high hardness, low expansion coefficient and excellent corrosion resistance, and the problems of bending deformation and corrosion of the ball screw and the guide rail during high-temperature curing are solved.

(13) According to the honeycomb core stretching-impregnating-curing integrated device, an additional complex and low-accuracy limiting fixing mechanism is not needed when a honeycomb is stretched, accurate positioning of any position in the stretching direction is achieved by means of mutual engagement force between the ball screw and the linear motion ball bearing, and the regularity of the honeycomb shape is guaranteed.

(14) In the honeycomb core stretching-impregnating-curing integrated device, in order to solve the problem that the linear expansion coefficients of the ball screw, the guide rail and the stretching machine frame are different, the connecting parts of the ball screw, the guide rail and the stretching machine frame are connected by adopting a detachable machine, the honeycomb is fixed by a threaded connecting piece during stretching, and the threaded connecting piece can be detached after the honeycomb is stretched to a preset position, so that the ball screw and the guide rail are free of interference expansion at high temperature, the problem that the metal guide rail is deformed after long-time multi-frequency high-temperature curing is solved, and the reusability of key parts is realized.

Drawings

FIG. 1 shows a schematic view of a honeycomb core preparation process of the present invention;

FIG. 2 shows a solid core stripe of glue printed;

fig. 3 shows a printed circular hole-shaped core bar glue (the circular holes are the core bar glue);

FIG. 4 shows a printed textured wicking tape (the texture being the wicking tape);

FIG. 5 shows a printed twill-shaped core strip glue (the twill is the core strip glue);

FIG. 6 is a schematic perspective view of a honeycomb stretch-dip-cure integrated apparatus in accordance with a preferred embodiment of the present invention;

FIG. 7 shows a schematic view of a stretching frame and a transmission unit in a preferred embodiment of the invention;

FIG. 8 is a schematic view of a transmission unit according to a preferred embodiment of the present invention;

FIG. 9 shows a schematic of a honeycomb tensile belt structure;

FIG. 10 is a schematic diagram showing the structure of a dipping unit in a preferred embodiment of the present invention.

Description of the reference numerals

The device comprises a stretching machine frame 1, a rectangular square tube 11, a fixed block 12, a transmission unit 2, a ball screw 21, a guide rail 22, a hand wheel 23, a linear motion ball bearing 24, a movable block 25, an inserted rod 26, a gum dipping unit 3, a gum dipping tank 31, a flow guide port 32 and a gum dipping tank frame 33.

Detailed Description

The invention is explained in more detail below with reference to the figures and examples. The features and advantages of the present invention will become more apparent from the description.

According to a first aspect of the present invention, as shown in fig. 1, there is provided a method for preparing an ultra-light high temperature resistant honeycomb core material, comprising the steps of:

step 1, core strip offset printing: printing core strip glue on the material blocks, wherein the width between two adjacent core strip glue is three times of the width of the printed core strip glue, paving the material blocks, and making the interval between the core strip glue in two adjacent material blocks equal and equal to the width of the core strip glue to obtain an uncured honeycomb laminated block;

step 2, curing the core strip glue: heating, pressurizing and curing the core strip glue of the honeycomb laminated block;

step 3, honeycomb stretching: stretching the honeycomb stacked block subjected to the pressure curing treatment until the honeycomb cells are stretched to a regular hexagon state;

step 4, dipping glue solution: dipping the stretched honeycomb laminated block in a dipping tank with high-temperature-resistant dipping glue;

and 5, curing the impregnating adhesive: and curing the high-temperature-resistant impregnating adhesive at a set temperature to obtain the honeycomb core material after curing is finished.

In the invention, before the core strip glue is printed on the block, the pretreatment method also comprises the step of pretreating the material of the block, and the pretreatment method comprises the following steps:

the polyimide acid resin is adjusted to have the viscosity of 50-200 cP through a solvent, the polyimide acid resin and the material block are uniformly coated on the material block by adopting a tape casting method according to the mass percentage of 1-6 wt% of the polyimide acid resin and the material block, and the polyimide acid resin is dried at the temperature of 100-150 ℃.

The polyimide acid resin for pretreatment is selected from ketone anhydride type, biphenyl anhydride type, ether anhydride or fluorine anhydride type polyimide resin, and the glass transition temperature is 280-350 ℃.

The solvent is one or more of diethylene glycol dimethyl ether, N dimethyl acetamide (DMAC) and N-methyl pyrrolidone (NMP).

The pretreatment process adopts a tape casting method, so that a continuous mechanical pretreatment technology of the fabric is realized, and the pretreatment of the material block is favorable for solving the problems of thickness direction permeation and edge diffusion in the core strip offset printing process.

In the present invention, the lump with a prescribed size is obtained by pre-cutting, such as cutting the pretreated fiber cloth into the lump with a prescribed size.

For step 1 printing of the core bar glue:

in the present invention, the material for the block may be any one or more selected from alkali-free (EW) glass cloth, electronic glass cloth, Polyparaphenylene Benzobisoxazole (PBO) fabric or non-woven fabric, Polyimide (PI) fabric or non-woven fabric, carbon cloth, and quartz cloth.

Furthermore, the thickness of the material block is less than or equal to 0.2mm, preferably 0.045-0.20 mm, and the temperature resistance is more than or equal to 300 ℃.

In the invention, the core bar glue is printed on the material block by adopting the screen printing equipment with double screen printing plates and automatic positioning, and the screen printing equipment is generally used in the field of textile printing or electronic printing and is not found to be used in the field of honeycomb core material preparation.

The automatic positioning screen printing equipment with the double screen printing plates can be the equipment in the prior art, and is not described again. Through the double-screen plate automatic positioning continuous printing process, the glue printing efficiency can be greatly improved, the prepared honeycomb is high in regularity, simple and convenient to operate and strong in applicability, the production requirements of multiple varieties and small batches can be met, and the process maturity development of honeycomb core material preparation is promoted.

In a preferred embodiment, as shown in fig. 2 to 5, the printed core stripe glue may be solid core, or may be non-solid core such as twill, net grain, circular hole, etc.; the solid core-shaped core strip glue is adopted, the strength of honeycomb joints is high, but the glue is easy to penetrate for material blocks with extremely thin thickness or good permeability, so that the adhesion phenomenon is caused; the non-solid core-shaped core strip glue is adopted, so that the glue penetration phenomenon can be effectively avoided.

In the invention, in order to meet the high-temperature requirement and reduce the glue penetration phenomenon, the high-temperature resistant honeycomb core strip glue is prepared and obtained from the following components in parts by mass:

in a preferred embodiment of the present invention, the polyimide resin is selected from thermosetting polyimide resins synthesized by the PMR method, alkynyl terminated or norbornene terminated.

In a preferred embodiment of the present invention, the reactive modifier is selected from any one or more of an alkynyl benzoxazine resin, a phenolic cyanate resin, a bismaleimide resin or the like, preferably an alkynyl benzoxazine resin. The reactive modifier has high reaction activity and good dissolving effect on the thermoplastic resin at the curing temperature.

In a preferred embodiment of the present invention, the thermoplastic resin is selected from one or more of a polyarylethersulfone resin, a polyamideimide resin, a polyimide resin, and the like, preferably a polyimide resin having a glass transition temperature Tg > 300 ℃, and the heat resistance is compatible with the host resin.

Further, the thermoplastic resin is thermoplastic resin particles having a particle diameter of 10 to 30 μm, preferably 10 to 20 μm. The particle diameter in the above range is advantageous for the stabilization of the thermoplastic resin in the corestock solution.

In a preferred embodiment of the present invention, the inorganic nanoparticles are selected from one or more of nano-silica, nano-titania, micro-nano graphite powder, etc., preferably nano-silica. The nano silicon dioxide has low cost and good dielectric property.

Further, the particle size of the inorganic nanoparticles is 50 to 250nm, preferably 150 to 200 nm.

In a preferred embodiment of the present invention, the solvent is selected from any one or more of acetone, butanone, cyclohexane, tetrahydrofuran, diethylene glycol dimethyl ether, N' -Dimethylacetamide (DMAC), and N-methylpyrrolidone (NMP), preferably acetone, which has a low boiling point, low toxicity, and low cost.

Further, the high-temperature resistant honeycomb core strip glue is prepared by a method comprising the following steps of:

step 1, adding 1/4-1/3 thermoplastic resin into an active modifier, dissolving at 100-150 ℃, cooling to below 80 ℃, adding the rest thermoplastic resin and inorganic nanoparticles into the active modifier, and stirring and dispersing to obtain a component A;

and 2, under the condition of stirring at room temperature, adding the polyimide resin and the component A into a solvent for dissolving and dispersing to obtain uniform and stable honeycomb core strip glue.

According to the invention, 1/4-1/3 thermoplastic resin is dissolved in the active modifier in advance, so that the prepared core strip glue has certain viscosity, the phenomenon that the subsequently added residual thermoplastic resin microparticles and inorganic nanoparticles are settled in the core strip glue solution is prevented, and the phenomenon that the core strip glue permeates to the back of the glass cloth during node gluing can be improved. If the amount of the thermoplastic resin dissolved in advance is too small and is less than 1/4, the viscosity of the core strand solution is too low, and the granular thermoplastic resin is liable to be precipitated; if the amount of the thermoplastic resin dissolved in advance is too much and higher than 1/3, the viscosity of the prepared corestrand gum solution is high, and the phenomenon of stringiness of the corestrand gum is likely to occur during printing.

In a preferred embodiment of the present invention, the temperature at which the thermoplastic resin is dissolved in the activity modifier is 100 to 130 ℃.

In a preferred embodiment of the present invention, the temperature of the remaining thermoplastic resin and inorganic nanoparticles added to the reactive modifier is 50 to 80 ℃.

In the present invention, when the panel is a fiber fabric, the weave structure of the fiber fabric includes any one or more of 0 °/90 °, ± 30 °, ± 45 ° or ± 60 °, and preferably 0 °/90 ° and ± 45 ° weave structures.

The organizational structures of two adjacent material blocks in the honeycomb laminated block can be the same or different, and comprise one or more of directions of 0 degree/90 degree, 30 degree, 45 degree and 60 degree, and preferably (1) the alternate lamination of 0 degree/90 degree and 45 degree is carried out; (2) two layers of the layers are alternately laminated at 0 degree/90 degrees and one layer of the layers is +/-45 degrees; (3) one layer of the film is 0 degree/90 degree and two layers of the film are plus or minus 45 degrees and are alternately laminated. Due to the special design of the weave structure of the fiber fabric, the prepared honeycomb core material has high node strength and excellent mechanical property at the high temperature of 300 ℃, and the preparation of the honeycomb core material with high compression resistance and high shear is realized.

In the present invention, the width of the core bar adhesive is 2.00mm to 11.00mm, and it is understood that the side length of the honeycomb can be as low as 2.75mm or less.

For step 2 curing of the core bar glue:

in the present invention, the curing of the core strip adhesive may be performed using a vacuum bag/autoclave molding process or a hot press.

The curing pressure is 0.5-1.0 MPa, the curing temperature is 200-350 ℃, and the temperature is kept for 2-6 h.

For step 3 honeycomb stretch: and stretching the honeycomb stacked block subjected to the pressure curing treatment by adopting self-made honeycomb stretching-gum dipping-curing integrated equipment until the honeycomb cells are stretched to a regular hexagon state.

As shown in fig. 6 and 7, the honeycomb core stretch-dip-cure integrated apparatus includes a stretcher 1, a transmission unit 2 carried by the stretcher 1, and a dipping unit 3 below the stretcher 1, wherein,

the stretching machine frame 1 comprises two parallel rectangular square tubes 11 for forming long sides of the stretching machine frame 1 and two parallel fixed blocks 12 for forming short sides of the stretching machine frame 1, and the fixed blocks 12 are mounted at two ends of each rectangular square tube 11 and form a rectangle with the two rectangular square tubes 11;

the transmission unit 2 comprises a ball screw 21 parallel to the rectangular square tube 11 and two guide rails 22 symmetrically arranged at two sides of the ball screw 21 and parallel to the ball screw; the opposite surfaces of the two fixed blocks 12 are provided with corresponding through holes, the two ends of the ball screw 21 and the guide rail 22 are inserted into the through holes of the fixed blocks 12 at the two sides, and a threaded connecting piece is arranged at the connecting part of the guide rail 22 and the fixed blocks 12 in a penetrating way to ensure that the two are fixedly connected; one end of a ball screw 21 extends out of the fixed block 12 and is connected with a hand wheel 23, linear motion ball bearings 24 are respectively sleeved on the ball screw 21 and the two guide rails 22, a movable block 25 is fixed on the linear motion ball bearings 24, the movable block 25 is used for fixing two ends of the honeycomb laminated slab with one of the fixed blocks 12, and the linear motion ball bearings 24 move away from the fixed blocks 12 in the length direction of the ball screw 21 by rotating the hand wheel 23 to stretch the honeycomb laminated slab; the preparation method of the honeycomb core material comprises the steps of cutting a material block, coating adhesive strips on the material block, superposing the material block, pressurizing and curing, stretching a honeycomb, dipping adhesive liquid and curing the honeycomb block, wherein the product after pressurizing and curing is a honeycomb laminated block;

the impregnation unit 3 includes an impregnation tank 31 for accommodating the glue solution, and the honeycomb lamination block is located in the inner space of the impregnation tank 31 when the honeycomb is stretched, and impregnation can be synchronously performed when the transmission unit 2 performs honeycomb stretching.

In the present invention, the connection manner of the rectangular square tube 11 and the fixing block 12 includes, but is not limited to, a threaded connection, a sleeve connection, and the like.

In the present invention, the radius of the cross-section of the guide rail 22 is the same as the radius of the corresponding through-hole in the fixed block 12.

In the invention, the ball screw 21 and the two fixed blocks 12 can be directly matched and connected; preferably, ball 21 and two fixed blocks 12 are connected through the copper sheathing cooperation, and the use of copper sheathing is convenient for spacing ball 21 and plays lubricated effect when rotatory to ball 21.

Preferably, the hand wheel end ball screw 21 extends out of the fixed block 12, the end of the ball screw 21 is machined into a rectangular block, a square groove is formed in the hand wheel 23 and matched with the rectangular block at the end of the ball screw 21, the hand wheel 23 is rotated to drive the ball screw 21 to rotate, and then the linear motion ball bearing 24 moves on the ball screw 21.

After the honeycomb core material is stretched and impregnated, the honeycomb core material is loaded by the stretching frame 1 and the transmission unit 2 and then enters a high-temperature oven for high-temperature curing, and the transmission unit 2 is used as a core component, so that the ball screw 21 and the guide rail 22 are obtained by materials with high temperature resistance, high strength and low thermal expansion coefficient, such as 0Cr17Ni4Cu4Nb martensitic stainless steel. The material has the characteristics of high strength, high rigidity, low thermal expansion coefficient and excellent corrosion resistance, realizes the high-temperature use of the honeycomb stretching device, prolongs the service life, and meets the requirements of high rigidity, deformation resistance and corrosion resistance of the multifunctional integrated stretching device on high-temperature-resistant honeycomb curing.

In the invention, after the guide rail 22 is matched with the through hole of the fixed block 12, the guide rail is further fixedly connected through a threaded connecting piece which is a detachable part; and the ball screw 21 is in clearance fit with the fixed block 12.

Because the structure of the stretching machine frame 1 is large and the requirement on precision is not large, the materials of the stretching machine frame 1 and the transmission unit 2 may be different. During high-temperature curing, the expansion coefficients of the drawing frame 1 and the transmission unit 2 may be different, so that the two expansion coefficients interfere with each other. For solving ball 21, the problem that guide rail 22 and stretching frame 1 linear expansion coefficient are different, ball 21, guide rail 22 and stretching frame 1 are connected the position and are adopted swing joint and can dismantle mechanical connection mode, pass through threaded connection spare fixed guide rail 22 when the honeycomb is tensile, the honeycomb is tensile to predetermined position after, can dismantle fixed threaded connection spare for, send into high temperature oven solidification processing back ball 21 and guide rail 22 noninterference inflation under high temperature, metal guide rail 22 after having solved long-time multifrequency high temperature solidification, ball 21 takes place the problem of warping, key part reusability has been realized.

In the invention, as shown in fig. 8, blind holes are arranged at equal intervals under the fixed block 12 and the movable block 25 along the direction vertical to the length direction of the ball screw 21, the insertion rods 26 are fixed in the blind holes, and the honeycomb laminated slab is driven to be stretched by sticking honeycomb stretching belts at the two ends of the honeycomb laminated slab and enabling the insertion rods 26 to penetrate through the pull rings of the honeycomb stretching belts. The distance between the blind holes on the fixed block 12 and the movable block 25 is determined according to the size of the honeycomb core, and generally, the smaller the honeycomb core cell is, the smaller the hole distance between the movable block 25 and the fixed block 12 is.

As shown in fig. 9, a honeycomb stretching tape is a commonly used auxiliary means for stretching a honeycomb, and before stretching, a tape-shaped paper or film is bonded to both end surfaces of a honeycomb laminated plate to form a pull ring, so that an insert rod 26 can be inserted to stretch the honeycomb. According to the honeycomb drawing device, an additional limiting fixing mechanism with low complexity and accuracy is not needed when the honeycomb is drawn, the accurate positioning of the honeycomb drawing position is realized by means of mutual engagement force between the ball screw 21 and the linear motion ball bearing 24, and the regularity of the honeycomb shape is further ensured by matching the inserted link 26 with the honeycomb drawing belt.

In the invention, a clamping groove is formed on the upper surface of a wall plate of a glue dipping tank 31, and a stretching frame 1 is erected on the glue dipping tank 31 and matched with the clamping groove of the glue dipping tank 31.

Further, the gum dipping tank 31 is fixedly connected with the stretching machine frame 1 through a threaded connecting piece. The stretching rack 1 and the glue dipping tank 31 are fixed through the threaded connecting piece, so that the problems that in the process of stretching the honeycomb laminated slab, the local stress of the honeycomb is uneven and the core material is broken due to the collision of the stretching rack 1 and the glue dipping tank 31 are avoided.

Furthermore, the size of the frame of the impregnation tank 31 is matched with that of the frame of the stretcher 1, and when the stretcher 1 is placed above the impregnation tank 31, the honeycomb core material is fixed on the stretcher 1 through the inserted bar 26 and is positioned in the impregnation tank 31, so that the stretching-impregnation process is synchronously performed, and the working efficiency is effectively improved.

In the invention, as shown in fig. 10, at least one flow guide port 32 is arranged at the bottom of the impregnation tank 31, the flow guide port 32 is connected with a conduit, the end of the conduit can be fixed at the side of the impregnation tank 31, and after the honeycomb impregnation is finished, the glue solution can be recovered through the flow guide port 32.

In the present invention, as shown in fig. 10, the dip unit 3 further includes a glue tank frame 33 for supporting the dip tank 32, and the dip tank 32 and the glue tank frame 33 are fixed by welding.

Further, the bottom of the glue groove frame 33 is provided with a roller, so that the whole device can move flexibly.

In the invention, the use method of the honeycomb core stretching-impregnating-curing integrated device comprises the following steps:

the insertion rod 26 passes through a pull ring of the honeycomb stretching belt and is fixed in blind holes on the fixed block 12 and the movable block 25;

erecting the stretching frame 1 in a clamping groove of a glue dipping tank 31, fixing the stretching frame through a threaded connecting piece, placing the honeycomb laminated plate in the glue dipping tank 31, pouring prepared specific gravity impregnation glue solution into the glue dipping tank 31, rotating the hand wheel 23 to stretch the honeycomb laminated plate gradually, measuring and monitoring the stretching of the honeycomb to a preset size by using a measuring tape, and stopping the rotation of the hand wheel 23;

after the dipping is carried out for a set time, opening a flow guide port 32 at the bottom of the dipping tank 32 to ensure that the liquid level of the glue solution falls below the bottom surface of the honeycomb core material, temporarily closing the flow guide port 32, drying the honeycomb core material in the dipping tank 31 for a period of time, draining off the residual glue, opening the flow guide port 32 again, and recovering the residual dipping glue;

dismounting the threaded connecting piece of the stretching frame 1 and the glue dipping tank 2, dismounting the threaded connecting piece between the guide rail 22 and the fixed block 12, then placing the stretching frame 1 with the dipped honeycombs in a high-temperature oven, setting curing parameters of the dipping glue, and completing the curing process of the honeycomb dipping glue;

and cooling the honeycomb core material to room temperature along with the furnace, taking the solidified and shaped honeycomb core material down from the stretching machine frame 1, and installing the stretching machine frame 1 back to the original position.

In the present invention, when the stretcher 1 with the impregnated honeycomb is placed in a high temperature oven, the stretcher 1 is turned upside down, and the stretcher 1 is positioned below, supporting the plunger 26 and the honeycomb core thereon.

For the step 4 impregnation cement:

in the invention, the high-temperature resistant impregnating glue is selected from one or more of PMR type polyimide resin (including norbornene end-capped type, end-capped ethynyl end-capped type, phenylethynyl end-capped type, bismaleimide end-capped type and the like) or polyimide acid resin.

For step 5 curing of the dip glue:

in the invention, the curing temperature of the high-temperature impregnating adhesive is 200-350 ℃, and the curing time is 2-6 h.

In the present invention, the preparation method further comprises a post-treatment of the honeycomb core material, the post-treatment comprising: and (3) processing the honeycomb height and the outer contour of the prepared honeycomb core material according to the requirement by adopting a slicing machine.

According to a second aspect of the invention, an ultra-light high temperature resistant honeycomb core material is provided, which is prepared by the preparation method of the first aspect.