Bonding technology of the hottest paper honeycomb

2022-08-22
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Bonding technology of paper honeycomb sandwich

Abstract: according to the production process of paper honeycomb sandwich material, the production process, the technologies that should be mastered in key processes and various process parameters are introduced in detail

key words: paper honeycomb sandwich adhesive process parameters

1 preface

composite sandwich materials are widely used in various industries, among which honeycomb sandwich materials are favored by more users because of their unique advantages. In recent years, domestic enterprises have increased the production of honeycomb core materials, especially paper honeycomb core materials. The function of honeycomb structure is to combine two panels into a piece of medium and provide stable support. Commonly used honeycomb materials include metal aluminum foil, thin plastic sheet, kraft paper (or parchment), glass fiber cloth, etc. According to the materials used, it can be roughly divided into three types, namely metal honeycomb, paper honeycomb and glass fiber cloth honeycomb. The following only introduces the manufacturing process and related technical parameters of paper honeycomb

2 manufacture of paper honeycomb core material

2.1 raw material

a paper

the commonly used paper material is kraft paper (or parchment), and its performance indicators are shown in Table 1

Table 1 technical performance indicators of kraft paper

project name indicators project name indicators paper width/mm 1000 breaking length/m 6000 fixed weight/g · m-2 wet breaking length/m 500 sizing thickness/mm 0.75 tensile strength/mpa 3 paper thickness/mm 0 1. Folding resistance/time 500 B adhesive

there are many kinds of adhesives used for bonding paper honeycomb core nodes, and the commonly used ones are white glue (i.e. polyvinyl acetate lotion adhesive) and acetal drying glue. The price of white glue is low, and it has good adhesion to fibers and porous materials, but its water resistance, acid resistance and alkaline resistance are poor; Acetal drying glue is slightly expensive, has good adhesion to paper, and has excellent water resistance, heat and humidity resistance, sun exposure resistance and medium resistance

when bonding the nodes of paper honeycomb core, these two adhesives have the characteristics of high node strength, strong surface adaptability and good process performance, which can be selected according to the actual situation

2.2 manufacturing process

the manufacturing of paper honeycomb core requires special equipment (not specifically introduced here), and its manufacturing process is:

roll paper on the shelf - Online - equipment (oven) temperature rise - glue injection - adjust the glue strip state - paper receiving - cutting - hot pressing - curing - trimming and cutting - Inspection - finished products

technical requirements for main processes:

(1) equipment (oven) temperature rise

roll paper When applying glue, the moisture of solvent will penetrate into the paper. The heating effect is an effective measure for the evaporation of solvent and moisture in the glue film. The temperature is generally controlled at 60 ~ 80 ℃

(2) glue injection

glue solution can generally be used directly. If the sensible viscosity is large, it can be diluted to 50 ~ 60s/(TU -4 cups)

(3) gluing

there are two gluing methods, longitudinal gluing and horizontal gluing. As shown in Figure 1 (omitted)

the more commonly used is longitudinal strip gluing. The gluing of the longitudinal strip is completed by the gluing roller, which is divided into two roller shafts, a and B, with a group of rollers arranged respectively, and equipped with corresponding glue storage tanks. When applying glue, the roll paper clings to the roller on both sides through tension tension, and then the glue strip is applied. The width of the adhesive strip shall be equivalent to the side length of the honeycomb (tolerance ± 0.1mm) and the thickness of the adhesive strip shall be 10 ~ 20 μ m。 The corresponding positions of the rollers on both sides are staggered by half, and the spacing of the adhesive strips (w/2) is shown in Figure 2 (omitted):

(4) adjust the adhesive strips

turn on the equipment to a low speed of 100 ~ 200R · min-1, and observe whether the adhesive strips are regular and uniform, the recorder degree before the width is appropriate, and whether there is lack of adhesive or overcoat. Until the adhesive strips on both sides are in order

(5) paper receiving

after the temperature and adhesive strip state meet the requirements, increase the running speed of the equipment to 300 ~ 400R · min-1, and start recording the number of paper receiving layers. According to the drying degree of the adhesive strip after passing through the drying channel, the pendulum can be adjusted at any time to return to the empty section running speed. It is required that the adhesive strip shall reach the semi dry level after being out of the drying channel. When the honeycomb laminated coil reaches the predetermined number of layers, it can be stopped

there is the following relationship between the number of layers of paper receiving and the length after the paper receiving is unfolded:

n0=2l/P n=2n0 (1)

where: N0 is the number of layers of paper receiving; N is the number of honeycomb core layers; L is the unfolding length of the paper receiving (unidirectional); P is the circumference of the paper receiving roller (average value)

the relationship between the number of layers of honeycomb core and the tensile length of core material is as follows:

where: n 'is the number of layers of honeycomb core; L is the tensile length of honeycomb core; A is the side length of honeycomb core lattice; Th is the paper thickness

there is the following relationship between the number of layers of the honeycomb core and the paper thickness:

n "=h/th (3)

where: n" is the number of layers of the honeycomb core; H is the thickness of the honeycomb strip when it is not stretched

the above equations (1) to (3) can calculate the number of layers of the honeycomb core. The three values of N, n 'and n "are approximately equal, which can be considered equal when the accuracy requirement is not high

(6) hot press curing

remove the scattered part of the cut paper block, then fold it in half, heat it on the hot press, and press it for curing. The curing pressure is about 0.6MPa. After drying at 120-160 ℃ for 3-5h, the pressure is maintained and cooled to below 80 ℃ for pressure relief

3 technical index of honeycomb core material

the honeycomb lattice made of kraft paper has a side length of 8mm and a paper thickness of 0.08mm. The honeycomb changes the deposited material of each layer from a plane to a curved surface along the maximum stress line of the pressure cover, and the stress direction of the core lattice is mainly on the nodes perpendicular to the panel and the plane direction of the panel. Its technical indicators are shown in Table 2

Table 2 technical indicators of paper honeycomb core

project indicators volume mass/kg · M-3 18.94 compression strength/mpa 2.42 tension along the vertical direction of the panel/n 9.89 tension along the horizontal direction of the panel/n 6.17 4 conclusion

the paper honeycomb core manufactured by the above method has uniform lattice, light weight, good scalability and low price. After being treated with flame retardant and impregnated with rubber, it can meet higher fire protection requirements, and the compression strength, shear strength and stiffness can be greatly improved to meet higher use requirements. The composite material made of this core material has the characteristics of light weight, good strength and rigidity, as well as sound insulation, heat insulation and good shape retention. It is widely used in aviation, aerospace, ships, vehicles, construction, sports equipment and furniture manufacturing, on the other hand. Therefore, paper honeycomb core composites have broad development prospects. (weiminxi Jiangxi Chaoyang Machinery Factory Technology Department, Pengze County, Jiangxi Province 332727)

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