A method of manufacturing a multilayer paper insulating material

 

(57) Abstract:

The inventive material is made from layers of paper on the basis of aromatic polyamide. Prior to forming the material each interior an even layer of paper impregnated with water or an aqueous solution of organic substances to a moisture content of 6-18% . Odd layers before bonding them with an even dried to a residual moisture content of 0-2%. Molded material calendarbut at a temperature of 240-280C and a pressure of 35-40 Psi. 1 Il., table 1.

The invention relates to a process of manufacturing a multilayer insulating materials of fiber-based heat-resistant aromatic polymers and can be used in the pulp and paper industry.

A known method of manufacturing a multilayer insulating cardboard, including the impregnation of paper, of synthetic fibers based on aromatic polyamides with water or an aqueous solution of organic substances, the formation of multi-layered paintings of several layers (sheets) of paper, extrusion of the material and its heat treatment. In this known method permeate all layers of paper, of which form a multi-layered canvas, impregnation leading to a moisture content of 6-30%.

Ei the same pressure conducting heat treatment - gradual heating to a temperature of 150-230oC (II stage). This process takes 10-15 minutes as organic substances used dimethylformamide, acetone, methyl ethyl ketone, methyl and ethyl alcohol, N-organic.

Pressing at room temperature and gradually warming up to 150-230oC eliminates the abrupt formation of gases and vapors and to get a good connection layers at relatively low temperatures.

The disadvantages of this method are: low rate of production of material related to the fact that removal of water vapor and gas from the impregnated paper requires quite a long time (10-15 min) due to sequence the operation of pressing (compression) and a lengthy process of heating the material to 150-230oC.

The aim of the invention is to increase the speed of manufacture of the material while maintaining its quality.

This objective is achieved in that in the method of manufacturing a multilayer paper insulating material, comprising the impregnated paper layers of synthetic fibers based on aromatic polyamides with water or an aqueous solution of organic substances to a moisture content of 6-18%, FD who have only each interior an even layer of paper, odd layers before connecting them with saturated even-numbered layers are dried to a residual moisture content of 0-2%, and pressing and heat treatment carried out simultaneously by calendering at a temperature of 240-280oC and a pressure of 30-40 MPa.

In the proposed method is implemented by a mixed mechanism of adhesion between the layers associated with specific adhesion due to interactions of the functional groups of macromolecules on the contacting surfaces formed by the mutual entanglement and the engagement of the fibers and fibrils of different layers due to quasimolecule education plasticizing gases and vapors in the interior is even, and by segmental compatibility and education additional physical links between the fibers and fibrils of different layers by transferring the fibre-forming polymer in the highly elastic state.

Translation boomgaarden polymers in highly elastic state on the borders of moist and dry layers at a temperature below the glass transition temperature is achieved due to the joint plasticizing effects of liquid and gaseous media and pressure.

When specified alternation of layers with moisture 6-18% of agnosti material after calendering is close to its equilibrium moisture content.

Impregnation even the inner layers to a moisture content of 6-18% is optimal, since at lower moisture content of these layers deteriorates the adhesion layer, and at higher humidity can form bubbles.

While pressing at a pressure below 30 MPa decreases the density and efforts adhesion between the layers; the pressure increase above 40 MPa leads to the degradation of physical and mechanical properties as a result of excessive monolithically material and possibly to mechanochemically polymer components of paper.

At temperatures below 240oC does not provide interpretation of the vitreous in the highly elastic state plasticized (wetted) internal layer at temperatures above 280oC starts the processes of recrystallization, thermal decomposition, which leads to deterioration of physical and mechanical properties of paper.

The proposed method allows to obtain a multilayer material with a speed of 10-30 m/min Choice of speed limits is determined by the time of drying of the outer layers, depending on the thickness of the layers and the heating temperature, the distance from the drying chamber to the calender and the number of layers of the multilayer material.

As dissolve the th or ethyl alcohols when their concentration in water up to 30%. The use of aqueous solutions of these substances at concentrations above 30% is impractical because does not change the physical-mechanical characteristics of the material.

The drawing shows a diagram of the method in obtaining a three-layer paper.

The method is as follows. The paper is made of synthetic fibers based on aromatic polyamides with three peals - 1, 2, 3 serves for pressing the heated rollers 4.5 calender. This paper from the roll 1, which is intended for internal even-numbered layer, passes through the impregnating bath (moisturizing device) 6, where it is moistened to a moisture content above the equilibrium moisture content of the paper. Paper rolls 2 and 3, intended for odd outer layers, passes zone IR-drying 7, where douchivaetsia to a moisture content below the equilibrium moisture content of the paper. Pressing is carried out at a pressure of 30-40 MPa, a temperature of 240-280oC, the speed of 10-30 m/min

The number of layers of material due to the strict requirements to the thickness of the material.

P R I m e R 1. Made of three-layer material.

As paper on the basis of aromatic polyamide paper used in industrial production, made of sin is the measure having an equilibrium moisture content of 5%. Paper for inner - even layer impregnated with water to a moisture content of 6-18%, the paper on the outer - odd layers are dried to a residual moisture content of 0-2%. Molded three-layer fabric by combining the dry and wet layers and calendarbut it when 240-280oC and a pressure of 30-40 MPa for 10-30 min (experiments 1-5).

P R I m m e R 2. Three-layer material was obtained analogously to example 1, but for impregnation internal - odd layer using an aqueous solution of dimethylacetamide (DMAA) concentrations of 10, 30, 40% (experiments 6-8) and an aqueous solution of dimethylformamide (DMF) of the same concentration (experiments 9-10).

P R I m e R 3 (prototype). Made of three-layer sheet material of the same paper as in example 1, 2. What all three of the paper soaks up humidity 7-18%, form a multi-layered canvas - stack the sheets between the plates of a press and pressed at a pressure of 15 MPa without heating (step I). Then, without removing the pressure exercised by the gradual heating of the plates 230oC (experiments 11-12). The materials obtained were subjected to the test.

Conditions of material production and characterization of the obtained materials is given in the table.

As can be seen from the data presented in tabatabaie 10-30 times while maintaining its adhesive strength. Moreover, the proposed method allows to obtain a multilayer material in a continuous way.

A method of MANUFACTURING a MULTILAYER PAPER INSULATING MATERIAL, comprising the impregnated paper layers of synthetic fibers based on aromatic polyamides with water or an aqueous solution of organic substances to a moisture content of 6 to 18%, the formation of multi-layered canvases, his pressing and heat treatment, characterized in that the impregnation is subjected to only one internal an even layer of paper, odd layers before connecting them with saturated even-numbered layers are dried to a residual moisture content of 0 - 2%, and pressing and heat treatment of the formed blade carried out simultaneously by calendering at a temperature of 240 - 280oC and a pressure of 35 to 40 MPa.

 

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