Foamed putty for filling gaps in sandwich composite materials and preparation method thereof

Abstract

The present invention provides a foaming putty for filling the gap of sandwich composite materials and a preparation method thereof, wherein the foaming putty includes component A and component B; the component A includes the following raw materials by mass fraction: 80-90% resin matrix, 1-5% diluent, 10-20% filler, 1-3% coupling agent, and 0-3% foaming agent; the component B includes the following raw materials by mass fraction: 75-100% curing agent, 0-25% filler, and 0-3% foaming agent. The present invention uses a solid hollow ball physical foaming agent, which can effectively avoid the secondary foaming problem of chemical foaming when used; an epoxy resin system is used to increase the adhesion of the putty, and a foaming putty matching a variety of curing temperatures is prepared by adjusting the ratio of each component. The foaming putty of the present invention has low flow state, high construction processability, and an adjustable foaming ratio; the foaming putty can fully fill the cavity formed by honeycomb cutting, while ensuring the strength of the foaming putty after foaming and curing molding.

Description

Technical Field

[0001] The invention relates to the field of resin-based composite material molding, and in particular to a foamed putty for filling gaps in sandwich composite materials and a preparation method thereof. Background Art

[0002] In the current sandwich composite material forming process, especially the honeycomb sandwich composite material forming process, foam film or foam adhesive is often used as the key material for the preparation of honeycomb structural parts. It is mainly used for the splicing of honeycomb sandwich cores in metal and non-metal honeycomb sandwich structures and the structural bonding between honeycomb sandwich cores and beams, ribs and partitions. The main focus is on the bonding quality, and the surface quality of the molding surface of the above-mentioned side facade is not considered. In actual use, the prepregs attached to the honeycomb and the side facade of the mold will form the following Figure 3 The cavity shown in the figure has a poor appearance after molding due to the existence of the cavity and the inability to apply sufficient pressure to the side elevation. The prior art solution is to fill a layer of foam film ( Figure 4 However, since the cavities formed by honeycomb cutting are not uniform, the continuous foam film can only fill a small part of the cavity. After foaming and curing (the foaming ratio of the existing foam film is between 2 and 4, and too high a foaming ratio will reduce the strength of the bonding structure), it cannot completely fill the cavity, resulting in insufficient expansion pressure during curing and failure to form a good surface.

[0003] The disadvantage of the foam film used in the prior art in the side elevation molding of the honeycomb sandwich resin-based composite material is that the foam film has poor fluidity and cannot effectively fill the honeycomb grid. In view of this, the present invention provides a foam putty for filling the gaps in the sandwich composite material and a preparation method thereof. The foam putty of the present invention fills the above-mentioned cavity, can completely fill the cavity, and provides a high-quality surface effect after curing. Summary of the invention

[0004] The main purpose of the present invention is to provide a foamed putty for filling the gaps of sandwich composite materials and a preparation method thereof. The foamed putty of the present invention has low fluidity, high construction processability, and an adjustable foaming ratio; the foamed putty can fully fill the cavity formed by honeycomb cutting, and the foamed putty can fill the entire cavity after being heated and expanded; at the same time, the strength of the foamed putty after foaming and curing is guaranteed.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: A foaming putty for filling gaps in sandwich composite materials, comprising component A and component B, wherein component A comprises the following raw materials in mass fractions: 80-90% of a resin matrix, 1-5% of a diluent, 10-20% of a filler, 1-3% of a coupling agent, and 0-3% of a foaming agent; The B component includes the following raw materials in mass fractions: 75-100% curing agent, 0-25% filler, and 0-3% foaming agent.

[0006] Preferably, the mass ratio of component A to component B is 1:0.3-0.4.

[0007] Preferably, the resin matrix is ​​an epoxy system, including one or more epoxy resins such as E51, E44, and E56.

[0008] Preferably, the curing agent is an amine curing agent, including one or more of polyetheramine, fatty amine, alicyclic amine, and N-aminoethylpiperazine, and the polyetheramine includes one or more of D400 and D230.

[0009] Preferably, the diluent is an epoxy reactive diluent, including one or more of 1,4-butanediol diglycidyl ether, cyclohexanediol diglycidyl ether, resorcinol diglycidyl ether, o-cresyl glycidyl ether, cyclopentanediol diglycidyl ether and trimethylol triglycidyl ether.

[0010] Preferably, the coupling agent includes one or more of chloropropyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane or γ-aminopropyltriethoxysilane; Preferably, the filler is one or more of calcium carbonate, fumed silica, and glass microspheres. Preferably, the foaming agent is one or more of expandable microspheres and hollow alumina spheres.

[0011] The present invention also provides a method for preparing the foamed putty for filling gaps in sandwich composite materials, comprising the following steps: S1. Add the resin matrix and diluent into the reaction kettle, heat to 55-65°C, stir and mix at a speed of 100r / min-300r / min for 1h-2h, add the coupling agent while stirring at a speed of 300ml / min-400ml / min, stir for 0.5h, add the filler and the foaming agent, stir and mix at a temperature of 55-65°C at a speed of 100r / min-300r / min for 1.5h-2.5h, and discharge the material to obtain component A; S2. Add curing agent, filler and foaming agent to the reactor in sequence, stir and mix at a speed of 150r / min~350r / min for 2h~3h, and discharge to obtain component B; S3, mixing component A and component B evenly according to a certain ratio to obtain the foamed putty.

[0012] The foamed putty prepared by the above technical scheme has the characteristics of low viscosity, and can be quickly and conveniently filled into the cavity pores using manual tools such as scrapers and scrapers, and has excellent construction processability; the curing temperature of the foamed putty is lower than the curing temperature of the prepreg in the filling target (5~10℃), so that when the prepreg matrix resin is in a flowing state and has a certain degree of plasticity, the foamed filling putty can expand and solidify and fill the entire cavity, and simultaneously apply a certain force to the prepreg to make it close to the mold, which helps to form a good surface effect.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention uses a solid hollow ball physical foaming agent, which can effectively avoid the secondary foaming problem of chemical foaming when used; by using an epoxy resin system, the adhesion of the putty is increased, and by adjusting the ratio of each component, a foamed putty matching a variety of curing temperatures is prepared.

[0014] 2. The present invention adds certain fillers and foaming agents to component A and component B respectively, so that the prepared foamed putty has low fluidity and high construction processability; by adjusting the ratio of the foaming agent and the filler, the foaming ratio is adjusted, and the foamed putty suitable for use under various materials and temperatures is formulated.

[0015] 3. The present invention optimizes the raw material ratio and the preparation process so that the foamed putty can fully fill the cavity formed by the honeycomb cutting, and the foamed putty can fill the entire cavity after being heated and expanded; at the same time, the strength of the foamed putty after foaming and curing is guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below in conjunction with the accompanying drawings: Figure 1 This is a rendering of the foamed putty prepared in an embodiment of the present invention filling the gap between the skin and the honeycomb material; Figure 2 This is the effect picture without using foam putty to fill the gap between the skin and the honeycomb material; Figure 3 It is a side elevation cross-sectional view of the honeycomb sandwich material and the mold; Figure 4 It is a side elevation cross-sectional view of the honeycomb sandwich material, foam film and mold. DETAILED DESCRIPTION

[0017] Embodiment 1: A foaming putty for filling gaps in sandwich composite materials, comprising a component A and a component B in a mass ratio of 1:0.3; The A component includes the following raw materials in mass fractions: E51 61.5%, E54 16%, 1,4-butanediol diglycidyl ether 1.5%, γ-glycidyloxypropyl trimethoxysilane 0.5%, glass microspheres 19%, and expandable microspheres 1.5%; The B component includes the following raw materials in mass fractions: D400 61.5%, D230 17%, expandable microspheres 1.5%, and glass microspheres 20%.

[0018] The method for preparing the foamed putty for filling the gaps of sandwich composite materials comprises the following steps: S1. Add E51, E54 and 1,4-butanediol diglycidyl ether into a reaction kettle, heat to 60°C, stir and mix at a speed of 200 r / min for 1.5 h, add γ-glycidyloxypropyltrimethoxysilane at a speed of 350 ml / min while stirring, stir for 0.5 h, add glass microspheres and expandable microspheres, stir and mix at a temperature of 60°C and a speed of 200 r / min for 2 h, and discharge to obtain component A; S2. Add D400, D230, expandable microspheres and glass microspheres into the reactor in sequence, stir and mix at a speed of 250 r / min for 2.5 h, and discharge to obtain component B; S3, mixing component A and component B evenly according to a certain proportion to obtain the foamed putty for filling the gaps of the sandwich composite material.

[0019] Embodiment 2: A foaming putty for filling gaps in sandwich composite materials, comprising a component A and a component B in a mass ratio of 1:0.4; The A component includes the following raw materials in mass fractions: E51 75.5%, γ-glycidyloxypropyltrimethoxysilane 0.5%, expandable microspheres 1%, and glass microspheres 23%; The B component includes the following raw materials in mass fractions: D400 100%.

[0020] The method for preparing the foamed putty for filling the gaps of sandwich composite materials comprises the following steps: S1. Add E51 into the reaction kettle, heat to 60°C, stir and mix at a speed of 200 r / min for 1.5 h, add γ-glycidyloxypropyltrimethoxysilane at a speed of 350 ml / min while stirring, stir for 0.5 h, add glass microspheres and expandable microspheres, stir and mix at a temperature of 60°C and a speed of 200 r / min for 2 h, and discharge to obtain component A; S2, add D400, expandable microspheres and glass microspheres into the reactor in sequence, stir and mix at a speed of 250r / min for 2.5h, and discharge to obtain component B; S3, mixing component A and component B evenly according to a certain proportion to obtain the foamed putty for filling the gaps of the sandwich composite material.

[0021] Embodiment 3: A foaming putty for filling gaps in sandwich composite materials, comprising a component A and a component B in a mass ratio of 1:0.35; The A component includes the following raw materials in mass fractions: E51 33%, E54 48.5%, 1,4-butanediol diglycidyl ether 1.5%, γ-glycidyloxypropyl trimethoxysilane 0.5%, expandable microspheres 2%, and glass microspheres 16%; The B component includes the following raw materials in mass fractions: D400 74.5%, N-aminoethylpiperazine 8%, expandable microspheres 1.5%, and glass microspheres 16%.

[0022] The method for preparing the foamed putty for filling the gaps of sandwich composite materials comprises the following steps: S1. Add E51, E54 and 1,4-butanediol diglycidyl ether into a reaction kettle, heat to 60°C, stir and mix at a speed of 200 r / min for 1.5 h, add γ-glycidyloxypropyltrimethoxysilane at a speed of 350 ml / min while stirring, stir for 0.5 h, add glass microspheres and expandable microspheres, stir and mix at a temperature of 60°C at a speed of 100 r / min~300 r / min for 2 h, and discharge to obtain component A; S2, add D400, N-aminoethylpiperazine, expandable microspheres and glass microspheres into the reaction kettle in sequence, stir and mix at a speed of 250r / min for 2.5h, and discharge to obtain component B; S3, mixing component A and component B evenly according to a certain proportion to obtain the foamed putty for filling the gaps of the sandwich composite material.

[0023] Comparative Example 1: In this comparative example, sodium bicarbonate is used as a chemical foaming agent to prepare a filling foam putty, wherein the foam putty comprises component A and component B in a mass ratio of 1:0.3; The A component includes the following raw materials in mass fractions: E51 61.5%, E54 16%, 1,4-butanediol diglycidyl ether 1.5%, γ-glycidyloxypropyl trimethoxysilane 0.5%, sodium bicarbonate 1.5%, and glass microspheres 19%; The B component includes the following raw materials in mass fractions: D400 61.5%, D230 17%, sodium bicarbonate 1.5%, and glass microspheres 20%.

[0024] The method for preparing the foamed putty for filling the gaps of sandwich composite materials comprises the following steps: S1. Add E51, E54 and 1,4-butanediol diglycidyl ether into a reaction kettle, heat to 60°C, stir and mix at a speed of 200 r / min for 1.5 h, add γ-glycidyloxypropyltrimethoxysilane at a speed of 350 ml / min while stirring, stir for 0.5 h, add sodium bicarbonate and glass beads, stir and mix at a temperature of 60°C at a speed of 200 r / min for 2 h, and discharge to obtain component A; S2. Add D400, D230, sodium bicarbonate and glass beads to the reactor in sequence, stir and mix at a speed of 250 r / min for 2.5 h, and discharge to obtain component B; S3, mixing component A and component B evenly according to a certain proportion to obtain the foamed putty for filling the gaps of the sandwich composite material.

[0025] The foamed putties prepared in Comparative Example 1 of Examples 1-3 above were respectively filled into the gaps of the skin-bonded honeycomb material, and the expansion ratio (80°C*1h+120°C*2h) of the filled putty and the front and rear tensile strengths of the skin-bonded honeycomb filled putty were measured. The specific test results are shown in Table 1.

[0026] Table 1

[0027] As can be seen from Table 1, in Examples 1-3, the flat compressive strength of the honeycomb panels prepared using the filling putty of the present invention is higher; compared with Example 1 and Comparative Example 1, due to the use of different foaming agents, the flat compressive strength of the honeycomb panel prepared using the filling putty of Comparative Example 1 is lower than that of Example 1.

[0028] Figure 1 This is a rendering of the effect of using the foamed putty prepared in the embodiment of the present invention to fill the gap between the skin and the honeycomb material. Figure 2 This is the effect picture without using foam putty. Figure 1-2 It can be seen that, by using the filling foam putty prepared by the present invention, the honeycomb pores are filled tightly and the side skin has a good appearance.

[0029] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A foaming putty for filling gaps in sandwich composite materials, characterized in that: The foaming putty comprises component A and component B; The A component includes the following raw materials in mass fractions: 80-90% resin matrix, 1-5% diluent, 10-20% filler, 1-3% coupling agent, and 0-3% foaming agent; The B component includes the following raw materials in mass fractions: 75-100% curing agent, 0-25% filler, and 0-3% foaming agent.

2. The foamed putty for filling gaps in sandwich composite materials according to claim 1, characterized in that: The mass ratio of the component A to the component B is 1:0.3-0.

4.

3. The foamed putty for filling gaps in sandwich composite materials according to claim 1, characterized in that: The resin matrix is ​​an epoxy system, including one or more of E51, E44, and E56 epoxy resins.

4. The foamed putty for filling gaps in sandwich composite materials according to claim 1, characterized in that: The curing agent is an amine curing agent, including one or more of polyetheramine, fatty amine, alicyclic amine, and N-aminoethylpiperazine, and the polyetheramine includes one or more of D400 and D230.

5. The foamed putty for filling gaps in sandwich composite materials according to claim 1, characterized in that: The diluent is an epoxy active diluent, including one or more of 1,4-butanediol diglycidyl ether, cyclohexanediol diglycidyl ether, resorcinol diglycidyl ether, o-cresyl glycidyl ether, cyclopentanediol diglycidyl ether and trimethylol triglycidyl ether.

6. The foamed putty for filling gaps in sandwich composite materials according to claim 1, characterized in that: The coupling agent includes one or more of chloropropyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane or γ-aminopropyltriethoxysilane.

7. The foamed putty for filling gaps in sandwich composite materials according to claim 1, characterized in that: The filler is one or more of calcium carbonate, fumed silica, and glass microspheres.

8. The foamed putty for filling gaps in sandwich composite materials according to claim 1, characterized in that: The foaming agent is one or more of expandable microspheres and hollow alumina spheres.

9. The method for preparing the foamed putty for filling gaps in sandwich composite materials according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Add the resin matrix and diluent into the reaction kettle, heat to 55-65°C, stir and mix at a speed of 100r / min-300r / min for 1h-2h, add the coupling agent while stirring at a speed of 300ml / min-400ml / min, stir for 0.5h, add the filler and the foaming agent, stir and mix at a temperature of 55-65°C at a speed of 100r / min-300r / min for 1.5h-2.5h, and discharge the material to obtain component A; S2. Add curing agent, filler and foaming agent to the reactor in sequence, stir and mix at a speed of 150r / min~350r / min for 2h~3h, and discharge to obtain component B; S3, mixing component A and component B evenly according to a certain ratio to obtain the foamed putty.

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