RU2486217C1 - Hot-melt binder, method for production thereof, prepreg and honeycomb panel based thereon - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to chemistry and the technology of producing semi-products from hot-melt compositions of epoxy resins, prepregs and laminates based thereon and can be used in making three-layer (sandwich) panels. The present invention can be used in aircraft floor panels which consist of composite cells and composite covers. The composition of hot-melt binder for a prepreg and a honeycomb panel based thereon contains epoxy-novolac resin, epoxy resin based on tetrabromodiane, epoxy-diane resin, high molecular weight epoxy resin, dicyandiamide, bis(N,N'-dimethyl carbamide)diphenyl methane and polysulphone. The method of making binder for prepregs involves mixing components with pre-dispersed dicyandiamide, bis(N,N'-dimethyl carbamide) in a portion of low molecular weight epoxy-diane resin, wherein high molecular weight epoxy resin and polysulphone are fused with the remaining portion of the low molecular weight epoxy-diane resin, the epoxy-novolac resin and the tetrabromodiane-based resin at temperature of 135-155°C, and then merged with the obtained dispersion at temperature of 55-65°C. The prepreg contains epoxy binder and fibre filler. A three-layer panel has a middle layer of a polymer honeycomb laminate and covers made from the prepreg.

EFFECT: obtaining preparations having self-extinguishing and self-adhesive properties for making fireproof honeycomb panels with high resistance to uniform tearing and delamination of cells from the covers, having low power consumption and high manufacturability.

5 cl, 3 tbl, 5 ex

Description

Technical field

The present invention relates to chemistry and technology for the production of semi-finished products from polymer composite materials (PCM), and more particularly to compositions of epoxy resins and layered products based on them, and can be used in the manufacture of three-layer (sandwich) panels from PCM. This invention can find its application, in particular, in the floor panels of aircraft, which consist of composite honeycombs and composite cladding.

State of the art

It is known that a decrease in its total mass is important in the design of any aircraft. It is important, in particular, to make PCM structures as light as possible, while maintaining the various strength characteristics that are required for a particular type, for example, a honeycomb floor panel. Even a small change in the surface (kg / m ² ) density of the floor panel will affect the relative change in the total take-off weight of the aircraft. Thus, it is necessary to make floor panels light in weight and with structural requirements that ensure their use in various types of aircraft and in specific areas.

They use various methods of reducing the weight of cellular sandwich panels without reducing the structural strength. One of the methods used to reduce weight is the exclusion of a separate adhesive (adhesive) layer [1]. This problem is solved by the manufacture of casing of prepregs, which are self-adhesive. The binder, which is used in such self-adhesive prepregs, must satisfy two requirements: to ensure high strength of the casing, while at the same time supporting its strong bonding with honeycomb core [2]. Self-adhesive claddings are described in detail and published in European patents EP 0927737 A1 and EP 0819723 A1 and U.S. Pat. Nos. 6,440,257; and 6,508,910.

Known blanks of floor panels manufactured by ONPP "Technology" according to TU 1-596-417-01 [3]. Honeycomb panels with fiberglass cladding based on fiberglass T-10-80 and adhesive EP-2MK. The disadvantage of these panels is the large mass, the low value of the peeling force of the casing from the honeycomb according to OST 1 90196-75 [4], as well as low flexural strength and extremely high deflection when bending a long beam according to OST 1.90265-78 [5]. Prepregs based on the used EP-2MK binder are not technologically advanced in processing (too high stickiness and low viability), can only be obtained on the basis of woven fillers, and also require long-term, high-temperature heat treatment: 4-6 hours at T = 160-170 ° C.

Known RF patent 1445163 "Method for producing an epoxy composition."

The invention relates to a method for producing an epoxy binder for producing prepregs and polymer composite materials with self-extinguishing properties, in particular, can be used in the manufacture of honeycomb structures. However, the presence of a liquid low molecular weight resin DEG-1 (diglycidyl ether of diethylene glycol) completely excludes the possibility of using prepregs based on this composition in the production of honeycomb structures by the combined molding method. When the temperature reaches above 80 ° C, and before curing begins at 125 ± 5 ° C, the binder from the upper skin flows down the walls of the honeycomb and at the same time, the adhesive strength of this skin to the honeycomb is insufficient for operation [2].

Known patent RF2176255 "Composition to obtain a binder for prepregs, a method of producing a binder for prepregs, prepreg and product."

The disadvantage of this binder composition is: the absence of flame retardants (products that reduce the combustibility of the material); the content of a large amount of epoxytriphenol and low molecular weight diane resin having high fluidity at elevated temperatures leads, as shown in the previous example, to the runoff of the binder from the upper skin, making it impossible to combine molding and gluing the skin with honeycomb core.

Closest to the proposed invention in technical essence and the achieved result is a composition for producing a binder for prepregs, a method for producing a binder for prepregs, prepreg and the product according to patent RU 2263690 "Binder for prepregs, prepreg and product made from it".

According to the invention, an epoxytriphenol resin, a low molecular weight epoxidian resin, hardeners dicyandiamide and bis (N, N'-dimethylcarbamide) diphenylmethane in a weight ratio of (40-60) :( 25-35) are taken to prepare a binder for prepregs: (3-6) :( 3-6) : (5.5-7.0) :( 0.05-2.0) solvent (0-90) and silicon dioxide (1-6) mass. parts.

A method of producing a binder for prepregs, which consists in mixing a pre-prepared paste - hardeners with a part of the molten low molecular weight epoxy resin - followed by combining the paste with an alloy of the remaining part of the low molecular weight epoxy resin, epoxy triphenol resin and high molecular weight epoxy resin at 160-170 ° C followed by 65-75 ° C.

The prepreg contains the proposed epoxy binder and fibrous filler in the ratio (30-42) :( 58-70) wt.%, Respectively. As a filler, glass, carbon, organic tows, ribbons, fabrics and threads, as well as their combinations, are used.

Compared with the invention according to patent 2176255 improved rheological properties of the proposed binder. However, the ultimate goal is to use it in the production of thick-walled monolithic high-strength PCM products, the curing of which is recommended to be carried out at a sufficiently high temperature of 180 ° C for at least 3 hours.

Cell panels manufactured using the claimed composition and a prepreg based on it cannot be used in floor structures of aircraft and other vehicles because of their combustibility that does not meet the requirements of AP-25 [6]. Their manufacturing process is possible only by separate molding using an additional adhesive film, which, as mentioned above, increases the complexity, energy consumption, and also reduces the productivity and profitability of production.

SUMMARY OF THE INVENTION

The objective of the invention is to develop a composition of a hot-melt binder and high-tech, precision prepregs based on it, obtained by melt technology, with a combination of self-extinguishing and self-adhesive properties, for manufacturing by the method of combined molding of honeycomb floor panels with high resistance to tearing and peeling of skin from honeycomb core, having reduced energy intensity and high manufacturability.

Products made using a binder, such as honeycomb panels, should have a small mass with high bonding strength of honeycombs with sheathing and have high adaptability to production and fire safety during operation.

In addition, the hot-melt binder and melt production technology of the so-called precision prepregs and products based on it should ensure their consistently high quality.

Precision prepregs are prepregs with high stability of properties in terms of binder content, thickness, and stability during storage and processing.

The problem is solved in that:

In the composition and method of manufacturing the hot-melt binder, prepreg and honeycomb panel, a binder was used, including: epoxy resin, high molecular weight epoxy resin, bis (N, N'-dimethyl carbamide) diphenylmethane, dicyandiamide, the binder additionally contains an epoxy resin and polybased tetrabisulfonamide based on in the following ratio of components (in mass.h)

- epoxy resin 16-38 - tetrabromodian based epoxy 26-32 - low molecular weight epoxy resin 20-40 - high molecular weight epoxy resin 0.5-7 - polysulfone 0.5-7 - bis (N, N'-dimethylcarbamide) diphenylmethane 0.5-1.5 - dicyandiamide 4.2-5.3

In addition, silicon dioxide (0.5-2 parts by weight) can be introduced into the composition.

In the method of preparing a binder for prepregs by mixing the components with preliminary dispersion of bis (N, N'-dimethylcarbamide) and dicyandiamide in the part of the low molecular weight epoxy resin, the dispersion is carried out at a temperature of 40-60 ° C, and the high molecular weight epoxy resin and (or) polysulfone are first alloyed with the remainder of the low molecular weight epoxidian resin, epoxynolac resin, tetrabromodian-based resin [7] at a temperature of 130-155 ° C, and then at a temperature of 50-60 ° C combine with the obtained dispersion under vacuum Mom 0.4-0.8 kgf / cm ² for 40-80 minutes;

in the prepreg, obtained on the basis of an epoxy binder and a fibrous filler in the form of bundles, ribbons, fabrics, the composition is used as a binder in the following ratio of components (in wt.%):

- epoxy binder 28-44 - fibrous filler 56-72,

and as a fiber filler, fiberglass roving with a linear density of from 1000 to 3000 tex or 8/3 satin weave fiberglass of high-modulus aluminosilicate fiber or aluminoborosilicate fiberglass is used;

in a three-layer panel consisting of a middle layer of polymersotoplast and sheaths of a polymer composite material, sheaths are made of the above prepreg by molding at a temperature of 120-130 ° C for 1-2 hours.

The invention makes it possible to produce precision prepregs with melt technology with self-adhesive properties that provide high strength and fire safety of the honeycomb panels made from them with minimal materials, electricity and labor costs, and the honeycomb panels made according to this invention, with close and even better weight parameters, have more high mechanical properties according to the results of special tests conducted for the floor panels of passenger aircraft and characterizing perception their operational loads.

The implementation of the invention

1. According to the invention, as components of an epoxy self-adhesive binder with reduced flammability are used:

- epoxynovolac resins (glycidyl ethers of novolacs SF-0121 and SF-0113) EN-6 (examples 1-3, 5) and UP-643 (example 4), manufactured according to TU 2225-11131395-2003;

- an epoxy resin based on tetrabromdian under the brand name UP-631, manufactured according to TU 2225-652-11131395-2008 (examples 1-5);

- epoxidian resins ED-22 (example 1, 4, 5), ED-20 (examples 2, 3), manufactured according to GOST 10587-84;

- powder polysulfone (the product of the interaction of diphenylpropane with dichlorodiphenylsulfone) grades PSK-1 (example 1), PSK-2 (examples 3-5), manufactured according to TU 6-06-46-90;

- high molecular weight epoxy resins: diaplast (TU 2225-386-11131395-97) (examples 1-3) and E-49P (TU 210-1592-76) (example 5);

- bis (N, N'-dimethylcarbamide) diphenylmethane - hardener No. 9, TU 2494-480-04872688-2006;

- dicyandiamide (examples 1, 2) GOST 6988-73 and brand Dyhard 100SF (examples 3-5) manufactured by ALZ Chem GmbH.

Silicon dioxide (aerosil (example 1), produced according to GOST 14922-77, or white soot (example 3-5) GOST 18307-78) can also be introduced into the composition of the components.

2. The preparation of the binder is carried out in mechanical mixing mixers with two mixers: high-speed gear (dispersant) and low-speed (frame). The mixer must be equipped with: a heating jacket and a vacuum system, for example, SPEMP-2 / 0.03-VK-R70 manufactured by NPP Dispod LLC.

3. Preparation of the prepreg is carried out from fabrics, woven tapes or from rovings and tows using melt technology in installations of the type UOL-300 produced by OJSC SAVMA or UPGM-700, developed by OJSC NIAT, as well as other models of imported production.

4. For the manufacture of the prepreg according to the examples of Table 2, fibrous fillers were used:

- example 1 - glass roving EC-13 1260N-78 (252) from aluminosilicate fiber TU 6-48-00205009-116-97;

- example 2 - glass roving from high-modulus aluminum-magnesium-silicate fibers of the VMP brand is produced under the brand RVMPN10-1260-78 according to TU 6-48-70-91 in the NPK Term;

- example 3 - fiberglass T-10-14 GOST 19170-73;

- example 4 - fiberglass T-10 (VMP) -4C TU 5952-183-05786904-04;

- example 5 - all fibrous materials listed in examples 1-4 (table 3).

5. The middle layer of the three-layer panel is made of polymersotoplast medium (60-100) and high (120-150 kg / m ³ ) density of domestic or foreign production. According to examples 1-4 of table 3, it is made of polymersotoplast PSP-1-2,0-96 TU 1-596-231-01.

The molding of three-layer panels is carried out in a multi-story hydraulic press with plates heated by thermal oil, at a temperature of 120-140 ° C and a pressure of 1-4 kgf / cm ² , for 1-2 hours.

Example 1

Dicyandiamide (5.3 parts by mass) and hardener 9 (0.5 parts by mass) with ED-22 epoxy resin (10 parts by mass) are dispersed in a mixer with a high-speed gear and low-speed frame mixer to a finely divided state. Mixing with dispersion is carried out under a vacuum of 0.6 ± 0.1 kgf / cm ² and a temperature of 50 ± 5 ° C for 60 ± 15 minutes. The resulting adduct (dispersion) is poured into polypropylene buckets with a tight-fitting lid and stored at a temperature of 20 ± 5 ° C for no more than 3 months or in a refrigerator for up to 1 year.

The ED-22 epoxy resin (19 parts by weight), EN-6 epoxy resin (29 parts by weight), UP-631 bromidian resin (26 parts by weight) are loaded into a mixer of a larger volume, heated to 145 -155 ° C, diaplast (5 parts by mass), polysulfone PSK-1 (5 parts by mass) are added in portions and stirred for 90 ± 30 minutes. The obtained melt is cooled to a temperature of 60 ° C and the previously obtained adduct (15.8 parts by weight) is loaded, after which the components are mixed for 60 ± 15 min at a temperature of 55 ± 5 ° C and a vacuum of 0.6 ± 0.1 kgf / cm ² .

The resulting binder is cooled to room temperature and poured into tightly closed polypropylene or galvanized buckets. The resulting binder is stored at a temperature not exceeding 25 ° C and not more than 3 months or up to 1 year in a refrigerator.

Binder Properties:

Viscosity at 80 ° C-8.9 Pa * s,

Gelling time at 120 ° C - 70 min,

Pot life at 80 ° C> 8 hours.

The woven fibrous filler is impregnated with the obtained melt of the binder using calender-type devices.

The binder molten in a spunbond device is poured through a slotted gap onto a transporting release liner, combined with fibrous material and alternately (2-3 cycles) is heated on a heated table and rolled in hot calendars, then the prepreg thus obtained is cooled and wound into rolls.

The resulting prepregs retain their rheokinetic properties, i.e. viability for further processing at a temperature not exceeding + 25 ° C for at least 3 months and at least 1 year at a temperature not exceeding -8 ° C.

The obtained prepregs are used in the manufacture of honeycomb panels by the method of combined hot pressing. The lower skin is laid out of the prepreg on a metal sheet treated with release grease, a honeycomb core is laid on top of the skin, cut into sheets of a predetermined height, the upper skin and a metal sheet treated with release grease are laid on top of the honeycomb.

The package thus assembled is placed between the heated plates of the hydraulic press. The molding pressure is applied at a rate of 2 to 4 kgf / cm ^{2 of the} moldable panel. Pressure curing is carried out at 125 ± 5 ° C for 1-2 hours. Press plates are cooled under pressure to 60 ± 10 ° C and the finished panels are removed from the press.

The disadvantage of the composition according to example 1 is the high viscosity of the binder at 80 ° C, which reduces the speed of obtaining a prepreg based on it.

Example 2

A binder is obtained in the following ratio of components:

- epoxynolac resin EN-6 16 - epoxy resin based on tetrabromdian UP-631 32 - epoxidian resin low molecular weight ED-20 40 - high molecular weight epoxy resin (diaplast) 7 - polysulfone PSK-2 0.5 - bis (N, N'-dimethylcarbamide) diphenylmethane 1,5 - dicyandiamide 4.2

The manufacturing process is similar to example 1, but the melt of epoxy resins with diaplast is carried out at a temperature of 155 ° C for 120 minutes, and the preparation of the binder is carried out at a temperature of 60 ° C in a vacuum of 0.4 kgf / cm ² for 80 minutes.

The resulting binder has a low viscosity that improves the processing conditions into prepregs, a short low-temperature curing cycle, but increased to 1.5 parts by weight the amount of hardener 9 significantly reduces the gelation time and viability of the binder during processing at 80 ° C.

Example 3

A binder is obtained in the following ratio of components:

- epoxynolac resin EN-6 29th - epoxy resin based on tetrabromdian UP-631 28 - epoxidian resin low molecular weight ED-20 29th - high molecular weight epoxy resin (E-49P) 5 - polysulfone (PSK-2) 3 - bis (N, N'-dimethylcarbamide) diphenylmethane 1,0 - dicyandiamide 5,0

The manufacturing process is similar to example 1, but the fusion of epoxy resins with high molecular weight resin E-49P and polysulfone PSK-2 is carried out at a temperature of 145 ° C for 90 minutes, and the preparation of the binder is carried out at a temperature of 55 ° C and a vacuum of 0.5 kgf / cm ² for 60 minutes.

Obtained in example 3, the binder, prepregs and honeycomb panels based on it have good processability in processing, sufficiently high mechanical properties and a combustibility level that fully meets the requirements of AP-25.

Example 4

A binder is obtained in the following ratio of components:

- epoxynolac resin UP-643 38 - epoxy resin based on tetrabromdian UP-631 27 - epoxidian resin low molecular weight ED-22 22 - high molecular weight epoxy resin E-49P 0.5 - polysulfone (PSK-2) 7 - bis (N, N'-dimethylcarbamide) diphenylmethane 0.9 - dicyandiamide 5.1

The manufacturing process is similar to example 1, but the fusion of epoxy resins with polysulfone PSK-2 is carried out at a temperature of 130 ° C for 40 minutes, and the preparation of a binder is carried out at a temperature of 50 ° C under a vacuum of 0.7 kgf / cm ² for 40 minutes.

The optimized ratio of hardener 9 to dicyandiamide reduces the curing time from 2 hours to 1.5 hours, reduces the curing temperature to 120 ° C while maintaining good heat resistance (glass transition temperature 145 ° C) and viability at 80 ° C.

Example 5

Analogously to example 1, a binder melt is made in the following ratio of components:

- epoxynolac resin EN-6 23 - epoxy resin based on tetrabromdian UP-631 28 - epoxidian resin low molecular weight ED-22 37 - high molecular weight epoxy resin (E-49P) 2.0 - polysulfone (PSK-2) 4.0 - bis (N, N'-dimethylcarbamide) diphenylmethane 0.9 - dicyandiamide 5.1

In contrast to example 1, the preparation of a melt of epoxy resins with high molecular weight epoxy resin E-49P and polysulfone PSK-2 is carried out at a temperature of 150 ° C for 90 minutes. The binder is prepared at a temperature of 50 ° C for 60 minutes under a vacuum of 0.6 kgf / cm ² .

The resulting binder has the most optimal set of physico-chemical properties:

1. The specified content of bromidian resin provides a stable self-extinguishing.

2. The accepted ratio of dicyandiamide with hardener 9 (5.1: 0.9) and epoxy resins provides long-term processing viability (> 7 hours at 80 ° C), low curing temperature (120 ° C) with a relatively short time (~ 1 , 5 hours) and a high glass transition temperature (143 ° C).

3. The selected combination of additives affecting the viscous-flowing properties of the binder in the processing mode at 80 ° C (diaplast, polysulfone, 2: 4 parts by weight) provides good fluidity (effective viscosity 3.7 Pa * s) and good drapability and stickiness received prepregs.

Based on the binder composition of Example 5, prepregs were made on the basis of various fibrous fillers and with different binder contents. From the obtained prepregs and honeycomb core PSP-1-3-96 with a height of 10 mm, samples of three-layer panels were molded and tested. Table 3 shows the mechanical parameters of the obtained panels in comparison with panels made of prepregs based on a binder composition according to example 3 of the prototype (patent RU 2263690).

From the examples in the table it is seen that due to the established ratio of epoxy resins and modifying additives (high molecular weight epoxy resin and polysulfone), the strength for uniform tearing and peeling of honeycombs from the skin on the proposed binder is 1.5-2.5 times higher than the similar values obtained with the use of a binder composition of the prototype.

The high bonding strength of the casing with honeycomb in all the above examples, which in most cases leads to the destruction of the latter, is achieved due to the optimal ratio of the binder with high viscosity epoxy resin, polysulfone and high molecular weight epoxy with low molecular weight low viscosity epoxy resin and the preparation of the binder . self-adhesive prepregs.

Table 1 The composition of the binder Name of components The composition of the examples, parts by weight Prototype one 2 3 four 5 Epoxytriphenol resin - - - - - 40-60 Epoxy resin 29th 16 29th 38 23 - Low molecular weight epoxy resin 29th 40 29th 22 37 25-35 Tetrabromodian Resin 26 32 28 27 28 - High molecular weight epoxy 5 7 5 0.5 2 3.6 Polysulfone 5 0.5 3 7 four - Dicyandiamide 5.3 4.2 5,0 5.1 5.1 5.5-7.0 Bis (N, N'-dimethylcarbamide) diphenylmethane 0.5 1,5 1,0 0.9 0.9 0.05-2.0 Silica - - - - - 1-6

Table 3 The parameters of the honeycomb panels based on the binder according to example 5 of table 1 (prototype: the composition of the binder and prepreg according to example 3 pat. RU) Name of parameters Glass roving Glass roving Fiberglass Fiberglass EU 13 1260N-78 RVMPN-1260 T-10-14 T-10 (VMP) -4C Example 1 Prototype Example 2 Prototype Example 3 Prototype Example 4 Prototype The binder content in the prepreg - inner lining 34 37 34 37 36 37 28 37 - outer skin 34 37 40 37 36 37 44 37 Weight 1 m ² panels, kg 2.1 2,3 2,5 2.6 2,5 2,8 2,8 3.2 Bending a long beam: - deflection at 450 N, mm 12 fourteen 9 eleven 16 eighteen 12 13 - fracture force, N 2030 1880 2400 2100 1060 970 1800 1650 Uniform separation of cells from skin, MPa 3,1 1.9 4.0 2.2 3.4 2.0 4.6 1.8 Flaking the skin from honeycombs on the drum, N / 75 mm 320 170 440 150 350 220 420 190 For panels with a height of honeycomb core PSP-1-3-96-10 mm and two-layer casing with an orientation of 0 ° / 90 ° Example 3 of the prototype is taken as the basis as the closest in composition of the hardener and in the composition of the prepreg of example 5.

Usage, Efficiency

The proposed binder is hot-melt, that is, it can be used to obtain prepregs that do not contain residual solvent, using melt technology; based on unidirectional textile and fibrous fillers made of fibers of various nature - glass, organo, and carbon, as well as their combinations (hybrid prepregs).

The use of melt technology in the production of prepregs is the most promising direction in terms of mechanization, environmental friendliness and safety of production, it can significantly improve the quality and stability of the so-called precision prepregs.

EFFECT: invention allows producing prepregs with self-adhesive and self-extinguishing properties, providing high strength and fire safety of honeycomb panels made from them with minimal materials, electricity and labor costs.

Cell panels made according to this invention, with close and even better weight parameters, have higher mechanical properties according to the results of special tests conducted for the floor panels of passenger aircraft and characterizing the operational loads perceived by them.

The proposed binder, prepreg and honeycomb panels can be made from components of domestic production, which, with equal technical parameters with foreign analogues, can reduce the cost of their production.

Cellular panels made of binder-based prepregs of the present invention are fireproof in accordance with AP-25 and NLGS standards.

The present invention solves the problem of creating new aviation structures, materials and technologies, in particular, can be used in the manufacture of the passenger compartment floor panel, which is a panel comprising a polymer honeycomb core and cladding of self-extinguishing fiberglass epoxy based on a self-adhesive binder and a fibrous filler in the form fabrics or rovings.

The panels are manufactured using the prepreg glueless technology of combined gluing molding, that is, a package of honeycomb core with prepreg casing based on fiber filler and an epoxy modified self-extinguishing binder is formed. The assembled package is placed between the heated plates of the hydraulic press and is molded at a pressure of 2 to 4 kgf / cm ² according to the temperature regime set for the developed binder.

The fire safety of the panels (compliance with the requirements of AP-25) is achieved by the introduction of tetrabromodian based epoxy resin binder.

In order to prevent the binder from draining from the upper skin along the honeycombs to the lower one and to increase the bonding strength of the upper skin with honeycombs, polysulfone is additionally introduced into the binder. Polysulfone, like diaplast, improves the adhesive properties of the prepreg, but unlike it, it increases the peeling strength of the skin from honeycombs more significantly and does not reduce the heat resistance of the composition, and instead of an epoxytriphenol resin, a highly viscous epoxynolac resin was introduced into the binder.

For high-quality bonding to the honeycomb core, the prepreg layers adjacent to the honeycomb core may contain a binder amount of 39 ± 5%, and the binder content is reduced to 33 ± 3% in the outer layers to increase the flexural rigidity of the panel.

Thanks to the applied technology of combined molding of skins and gluing them with honeycomb, the laboriousness of the panel manufacturing process, the production cycle and the cost, due to the absence of expensive glue, a number of auxiliary materials used in separate molding, energy costs for production, respectively, the cost of the resulting panel are reduced.

Information sources

1. Kardashov D.A. Petrova A.P. Polymer adhesives. Creation and application. - M.: Chemistry, 1983.

2. Shokin G.I. Development of high-tech reinforced plastics for multilayer aircraft structures. - diss. Cand. tech. sciences. - Moscow: 1988, VIAM.

3. TU 1-596-417-11 blanks of floor panels

4. OST 190196-75 Glues. Test method for strength when peeling the adhesive joints of the honeycomb core with the skin

5. OST 1.90265-78 Plastics. Method for determining the bending strength of three-layer materials with honeycomb core.

6. AP-25. Aviation Rules. Part 25.

7. V.A. Bobylev. Special epoxy resins for adhesives and sealants. Glues, sealants, technologies No. 5, 2005

Claims (5)

1. The composition for producing a hot-melt binder for the prepreg and a honeycomb panel based on it, containing epoxidic low molecular weight resin, high molecular weight epoxy resin, bis (N, N'-dimethylcarbamide) diphenylmethane, dicyandiamide, characterized in that it further comprises an epoxy resin resin, epoxy based on tetrabromodian and polysulfone in the following ratio of components, parts by weight:
epoxy resin 16-38 tetrabromodian epoxy 26-32 low molecular weight epoxy resin 20-40 high molecular weight epoxy 0.5-7 polysulfone 0.5-7 bis (N, N'-dimethylcarbamide) diphenylmethane 0.5-1.5 dicyandiamide 4.2-5.3 2. The composition for producing a hot-melt binder for the prepreg and the honeycomb panel based on it according to claim 1, characterized in that it is additionally introduced silicon dioxide in an amount of 0.5-2 wt.h. 3. A method of obtaining a hot-melt binder for prepregs by mixing the components according to claim 1 with preliminary dispersion of dicyandiamide, bis (N, N'-dimethylcarbamide) diphenylmethane in the part of the low molecular weight epoxy resin, characterized in that the polysulfone and high molecular weight epoxy resin are first alloyed with the remaining part low molecular weight epoxy resin, epoxy resin, epoxy resin based on tetrabromodian at a temperature of 130-155 ° C, and then at a temperature of 50-60 ° C and a vacuum of 0.4-0.8 kgf / cm ² combine with the resulting dispersion. 4. The prepreg, obtained on the basis of a hot-melt epoxy binder and fiber filler in the form of glass, carbon, organic tows, tapes, fabrics and / or combinations based on them, characterized in that the composition according to claim 1 is used as a binder in the following ratio of components , wt.%:
epoxy binder 28-44 fiberfill 56-72 5. A three-layer panel consisting of a middle layer of polymersotoplast and casing made of a polymer composite material, characterized in that the casing is made of a prepreg according to claim 4.