RU2592578C1 - Method of improving physical and mechanical parameters of fibre-glass - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to composite materials. Method involves preliminary processing of glass-fibre filler containing sizing agent-"paraffin emulsion", low-temperature plasma of glow discharge of alternating current with frequency 50 Hz using air as working gas at low pressure, subsequent impregnation with polymer binder. Treatment of glass-fibre filler is carried out in area of negative luminescence of abnormal glow discharge of low-temperature plasma. Continuous change of working gas with maintenance of constant total pressure is carried out. Method includes impregnation with moisture-resistant polymer binding materials, having low indices of moisture absorption.

EFFECT: improved interlayer adhesion, moisture resistance.

4 cl, 1 dwg, 2 tbl, 4 ex

Description

FIELD OF THE INVENTION

The invention relates to the field of composite materials, in particular to methods for manufacturing composite materials, including the preliminary processing of fiberglass materials used as mechanically strong fillers, in order to increase adhesion between the filler and the binder in the composite.

State of the art

It is known that fiberglass is initially characterized by frictional and electrophysical properties, which make its use in technological processes ineffective. This necessitates a modification of its surface properties. One of the traditional methods of this modification is the processing of sizing compositions, as a result of which new frictional and electrophysical properties are given to textile materials. The oiling process contributes to the adhesion of the fibers, the alignment of the friction forces along the fibers and threads and thus significantly reduces the likelihood of surface microcracks that reduce the strength of the fiber. Another equally important task of sizing is to increase the adhesion properties of fiberglass.

Sizing depending on the purpose of continuous fibers are divided into textile and straight. Textile sizing protect the thread from abrasion and destruction during its processing into textile products. The purpose of direct sizing (sizing) is to improve the adhesion of the surface of fiberglass with polymer binders in fiberglass.

Fibers can be processed with direct sizing both in the process of their production and after thermochemical removal of textile sizing fibers from the surface (Gutnikov S.I., Lazoryak B.I., Seleznev A.N. Glass fibers. - M.: Moscow State University named after M. V. Lomonosov, 2010).

The prior art method for removing textile sizing, based on thermal annealing of fiberglass filler at 250-400 ° C in air or an oxygen atmosphere (Andrievskaya G.A. High-strength oriented fiberglass. - M .: Nauka, 1966).

The prior art also knows a method for processing fiberglass materials, namely, removing the sizing agent by boiling the fiberglass filler in water, followed by carbon tetrachloride treatment during the day (Aut. St. USSR No. 767039, C03C 25/68, 09/30/1980).

The prior art also knows a method of processing fiberglass materials, namely, removing the sizing by desizing the glass fabric by processing it with a chromium mixture (Aut. St. USSR No. 167807, C03C 25/70, D06L 1/06, publ. 01.01.1965).

The main disadvantages of the above methods of processing fiberglass materials are: firstly, the incomplete removal of the lubricant from the fiberglass filler, which deteriorates the adhesion between the filler and the binder, and secondly, their high energy intensity and environmental hazard associated with harmful emissions into the atmosphere, and, in thirdly, the physical and mechanical properties of the fiber deteriorate due to moisture adsorption by the fiber and the appearance of new defects (Kiselev B.A. Fiberglass. - Moscow: Moskhimizdat, 1961, p. 27).

Also known from the prior art is a method of preparing a fiberglass filler for applying a polymer binder, which consists in the fact that the fiberglass filler containing a paraffin emulsion sizing is placed in the cathode drop region and subjected to a glow discharge of an alternating current of 50 Hz, 50-100 mA , with an exposure time of 30 to 90 s, at a working gas-air pressure of 1-20 Pa (RF patent No. 2270207, C08J 5/24, B32B 27/36, B32B 27/38, C08J 5/08, C03C 25/62 , C08K 7/14, publ. 02.20.2006).

The closest analogue of the invention is a method of manufacturing a prepreg, which consists in the fact that a fiberglass filler containing a textile sizing "paraffin emulsion" is placed in the region of the cathode drop and is exposed to a glow discharge of alternating current with a frequency of 50 Hz, a force of 50-100 mA, for a duration of exposure from 30 to 90 s, at a working gas-air pressure of 1-20 Pa (RF Patent No. 2270208, C08J 5/24, B32B 27/36, B32B 27/38, C08J 5/08, C03C 25/62, C08K 7 / 14, publ. 06/10/2006). Fiberglass according to this method is obtained on the basis of low-temperature plasma-treated fiberglass and an epoxy binder from the cured resin ED-20. When using this method, the mechanical properties of fiberglass remain unchanged, but at the same time its resistance to water and a humid environment increases significantly.

The main disadvantages of this method are: firstly, the use of epoxy resin in the manufacture of fiberglass, which due to high moisture absorption coefficients leads to a rapid decrease in the physicomechanical parameters of the composite in the presence of moisture, and secondly, the treatment modes proposed in the method do not provide an increase in adhesion filler of fiberglass roving and a binder of a polymeric material based on a curable resin, which, as a result, does not provide high parameters of mechanical strength kloplastika.

SUMMARY OF THE INVENTION

The objective of the invention is to significantly increase the physico-mechanical parameters of composite materials, namely fiberglass, using the most common and relatively cheap fiberglass fillers to obtain high-strength and water-resistant fiberglass.

The technical result is to increase interlayer adhesion, increase moisture resistance.

The problem is solved in that in a method for producing fiberglass, including pretreatment of a fiberglass filler containing a sizing - "paraffin emulsion" with a low-temperature plasma of a glow discharge of an alternating current with a frequency of 50 Hz in air, under reduced pressure, subsequent impregnation with a polymer binder, according to the invention, pretreatment of fiberglass the filler is carried out in the region of the negative glow of the abnormal glow discharge of the low-temperature plasma, while by continuous shift of working gas with maintaining the total pressure constant, and then impregnated with a water-resistant polymeric binders having low levels of moisture absorption.

In an embodiment of the invention, polyester resin binders are used as moisture resistant polymer binders.

In an embodiment of the invention, a low-temperature glow discharge plasma is processed with a current density of 0.1 mA / cm ² .

In an embodiment of the invention, the working gas is changed at a flow rate of 50 ml / min.

Brief Description of the Drawings

Details, features, and also advantages of the invention follow from the following description of embodiments of the claimed method using the drawing, which shows:

FIG. 1 is a diagram of an apparatus for conducting plasmachemical processing of a glass fiber filler.

In FIG. 1 the numbers indicate the following positions: 1 - a vacuum reaction chamber, 2 - a fiberglass sample in the form of a tape, 3 - a vacuum system, 4 - a vacuum measurement system, 5 - a system for measuring and adjusting the working gas flow, 6 - a continuously adjustable damper, 7 - a block discharge power, 8 - a pair of plane-parallel metal electrodes, 9 - a rewind system.

Disclosure of invention

The inventive method allows the use of high-strength and water-resistant fiberglass fiberglass fillers containing the most common lubricant "paraffin emulsion", without the need for removal and application of a special sizing to ensure high adhesion of the filler to the binder. The method is simple to implement and environmentally friendly.

In contrast to the known methods, according to the claimed method, fiberglass is made on the basis of moisture-resistant polymer binders having low moisture absorption and a fiberglass filler having high adhesion to the binder due to pre-treatment of the fiberglass filler in a low-temperature glow discharge plasma in a controlled continuous change of the working gas.

Under the influence of a glow discharge, a number of physicochemical transformations occur, as a result of which the surface properties of the glass fiber filler change sharply. A thin layer forms on fiberglass, characterized by the presence of chemically active peroxide groups and long-lived free radicals. Peroxide groups easily decompose with the formation of chemically active radicals, which, together with long-lived free radicals of various nature formed in the plasma, lead to chemical bonds between the binder and the filler at the polymer / glass interfaces. The method is simple to implement and environmentally friendly.

The modes of plasma-chemical processing, as well as the type of discharge, are of great importance for obtaining the required technical result and are an important element of the invention.

Thus, the region of combustion of the discharge, in which the processed surface of the material is located, is of great importance.

In the region of the negative glow of the abnormal glow discharge, intense ionization of atoms and gas molecules occurs. Therefore, this region is characterized by the highest concentration of chemically active particles, namely electrons with energies of 15-30 eV, capable of effectively breaking chemical bonds, leading to the formation of a high concentration of free radicals on the surface of the processed material. When removed to the atmosphere, some of the radicals have a high lifetime of 1-30 days, and some die, interacting with atmospheric water vapor, passing into peroxide groups. At the next stage of the fiberglass manufacturing process, long-lived free radicals enter a chemical reaction with the resin at the stage of impregnation of fiberglass or roving fibers with it. As a result, chemical crosslinking is formed at the polymeric binder fiber interface. In the region of the cathodic drop in the discharge, the energies of the active particles are much higher up to 300 eV, but their concentration and interaction efficiency (interaction cross section) are 10 or more times lower. Therefore, in the area of negative luminescence, processing is more than an order of magnitude more efficient.

The declared current density of a glow discharge, equal to 0.1 mA / cm ² , is an important indicator, since in a gas-discharge plasma there are competing processes on the treated surface of the material. For example, the process of producing chemically active centers and the process of destruction (etching) of the surface. Therefore, the discharge current density has a ceiling above which, due to the high speed of the surface destruction process, the surface activation efficiency decreases. In addition, the surface temperature is an important parameter during the plasma-chemical treatment. Too dense and energetic plasma (in particular, the lack of a corona discharge plasma in a strong local heating of the surface) leads to a strong heating of the surface of the material and, as a result, to an increase in the rate of destruction of surface layers and the death of generated chemically active centers. If the discharge current density is too low, the cross section of the plasma formed between plane-parallel electrodes begins to decrease, and accordingly the area and uniformity of processing decreases, more precisely, the surface treatment of the material will not be uniform.

The selected discharge pressure is also of great importance. The lower the pressure of the glow discharge, the wider the active regions in it, and, in particular, the region of cathodic incidence and the region of negative luminescence, and accordingly there are less requirements for the accuracy of the location of the treated material surface along the interelectrode space and, as a consequence, the uniformity of processing.

Work in flow mode, i.e. Plasma gas changing mode is also important. In most plasma-chemical processing works, this parameter was not controlled and was absent. However, a slow change of gas leads to the fact that, firstly, the temperature of the gas in the reactor and the materials contained in it increases substantially, and secondly, organic low molecular weight degradation products of the processed material are adsorbed in it, forming a polluting brittle polymer film on its surface, in thirdly, degradation products interact with chemically active centers generated on the surface of the material, destroying them.

Thus, the selected plasma-chemical treatment modes, as well as the type of discharge, are of great importance for obtaining the desired final result, for example, the mechanical parameters of the final material.

To prove the work of the proposed method, tests were carried out on fiberglass samples made using fiberglass filler in the form of fiberglass T-13 brand with a paraffin emulsion sizing.

The processing of fiberglass filler in a low temperature glow discharge plasma is as follows. A fiberglass sample in the form of a tape 1 m wide (2) is placed in the evacuated reaction chamber (1). Using a vacuum system (3), a vacuum is created in the chamber, which is measured using a measuring system (4). To operate in flow mode, a continuous flow of working gas is supplied at a predetermined speed through the gas flow measurement and adjustment system (5). Using a special damper (6) that regulates the gas pumping rate, a constant total pressure in the chamber is maintained. From the discharge power supply unit (7), an alternating voltage with a frequency determined by the industrial network is supplied to the electrodes (8) by a supply discharge. The value of the supply voltage is set from the following conditions: firstly, the condition for an abnormal glow discharge necessary for uniformity of processing of the fiberglass filler and, secondly, the value of the discharge current density should provide the necessary modification of the surface of the fiberglass filler to ensure its high adhesion to the polymer binder in the manufacture of the composite . They include a system for rewinding (9) a fiberglass roll, which ensures continuous and uniform passage of each fiberglass section in the central region of the space between pairs of plane-parallel electrodes (8). The interelectrode distance is selected based on the required gas pressure in the chamber and, accordingly, is wider than the cathode dark space and such that both sides of the fiberglass are in the region of the negative glow of the abnormal glow discharge. After processing, the voltage supply is stopped, the discharge is turned off, the system is connected to the atmosphere and the processed fiberglass roll is removed.

Fiberglass samples as follows.

The first of the prepared samples 300 × 300 mm in size cut from a fiberglass roll was laid on a metal plate. Next, a binder resin was applied to the fiberglass with a brush. After applying and impregnating the first sample, a second sheet of fiberglass was laid on its surface and the resin deposition process was repeated. The operations described above were repeated until a bag of fifteen layers of fiberglass impregnated with a binder resin was made. Then, a sheet of fluoroplastic film was laid on the outer surface of the fabricated package, and a solid outer metal plate having a high resistance to bending deformation was laid on it. A load was placed on the outer metal plate, providing a compressive external pressure of 0.2 kg / cm ² . The sample was stored under external pressure for 1 day.

The molded samples were placed in a programmable thermostat (in the oven), in which, according to a certain program, the necessary polymerization modes, including time and temperature, were sequentially set (table 1). At the end of the curing process, the samples were freed from the fluoroplastic film.

Assessment of the mechanical strength (interlayer adhesion) of fiberglass samples was carried out by the normal separation method (the "fungus" method) on a tensile testing machine.

For testing, fiberglass samples obtained in the form of 300 × 300 mm plates were cut using circular cutters into round samples with a diameter of 25 mm. The surface of round samples and “fungi” and in the places of gluing is treated with sandpaper, dust-free and degreased with ethyl alcohol. Glue is applied evenly on the surface of the samples and the “fungus”, the “fungus” is pressed against the sample, providing alignment of the surfaces to be glued, and held for at least 1 day until the adhesive has cured.

To carry out mechanical strength tests, a “fungus” with a glued fiberglass specimen is placed in a special clamp fixed in the lower fixed grip of the tensile testing machine. The upper part of the test "fungus" is fixed in the movable grip of the machine, after which peeling of the sample is carried out.

At the time of interlayer destruction of the sample, accompanied by the separation of the "fungus", the force of separation is recorded. The interlayer adhesion index of the sample was calculated as the ratio of the separation force to the cross-sectional area of the sample. For the indicator of interlayer adhesion of fiberglass take the average value obtained in testing 10 samples.

Mechanical strength tests were carried out on two types of fiberglass:

1 - using as a filler the original (untreated) fiberglass and

2 - based on fiberglass treated in plasma according to the claimed method.

The water resistance of fiberglass samples was evaluated on the initial samples (without treatment in water) and samples subjected to treatment in water at a temperature of 100 ° C for 3 hours, followed by comparative mechanical tests using the normal detachment method on a tensile testing machine.

Table 1 shows the type and composition of the resin used as a polymer binder in fiberglass, and the parameters of the curing processes for various examples according to the invention.

Table 2 shows the results of mechanical tests before and after processing in boiling water fiberglass samples made using the original fiberglass fabric (not processed in plasma) and processed fiberglass subjected to plasma-chemical processing according to the invention as a filler.

The invention can be illustrated by the following examples:

Example 1

A sample of fiberglass in the form of a tape 1 m wide (2) is placed in a vacuum reaction chamber (1). Using a vacuum system (3), air is pumped out of the chamber to a pressure of less than 1 Pa. Then, through the system of measurement and adjustment of the working gas (5), a stream of air is gradually supplied with a gas flow rate of 50 ml / min Using the damper (6) with a continuously adjustable outlet size, the speed of pumping air out of the vacuum chamber is adjusted so that the working pressure of 3 Pa is established in the chamber. From the discharge power supply unit (7), an alternating voltage of 50 Hz is supplied to the electrodes (8) and a discharge is ignited with a current density of 0.1 mA / cm ² . They include a system for rewinding (9) a fiberglass roll, which ensures continuous and uniform passage of each fiberglass section in the central region of the space between pairs of plane-parallel electrodes (8). The interelectrode distance is selected based on the required gas pressure in the chamber and, accordingly, is wider than the cathode dark space and such that both sides of the fiberglass are in the region of the negative glow of the abnormal glow discharge. After processing, the voltage supply is stopped, the discharge is turned off, the system is connected to the atmosphere and the processed fiberglass roll is removed. Next, two types of fiberglass are made: 1 - using the source (untreated) fiberglass as a filler and 2 - based on a plasma-treated fiberglass. For the manufacture of a polymeric binder in fiberglass, a Polyipol 385 polyester resin is selected using the technology indicated above.

Table 2 shows the comparative physical and mechanical characteristics of fiberglass, made on the basis of polyester resin Polipol 385 and T13 fiberglass treated in a low-temperature plasma according to example 1, and untreated fiberglass.

Example 2

The preparation of a fiberglass filler and the preparation of fiberglass samples are carried out analogously to example 1. But unlike example 1, fiberglass is obtained using a polymer binder based on the Depol X400 polyester resin. Comparative physical and mechanical characteristics of fiberglass with a polymeric binder made of Depol X400 polyester resin are shown in table 2.

Example 3

The preparation of a fiberglass filler and the preparation of fiberglass samples is carried out analogously to example 1. But unlike example 1, fiberglass is obtained using a polymer binder based on a polyester resin Depol X 310. The comparative physical and mechanical characteristics of fiberglass with a polymer binder made from resin Depol X 310 are shown in table 2.

Example 4

The preparation of a fiberglass filler and the preparation of fiberglass samples are carried out analogously to example 1. But unlike example 1, fiberglass is obtained using a polymer binder based on a polyester resin NPS 9501T. Comparative physical and mechanical characteristics of fiberglass with a polymeric binder made of resin NPS 9501T are shown in table 2.

The data of table 2 indicate that the preliminary plasma-chemical treatment of the fiberglass filler in the modes specified in the claimed method leads to a significant increase in the interlayer adhesion in fiberglass made using this fiberglass filler. Fiberglass, obtained on the basis of prepared according to the claimed method of fiberglass filler, have high strength characteristics and after prolonged exposure to hot water at a temperature of 100 ° C.

Claims (4)

1. A method of increasing the physicomechanical parameters of fiberglass, including pretreatment of a fiberglass filler containing a sizing - "paraffin emulsion" with a low-temperature plasma of a glow discharge of alternating current with a frequency of 50 Hz, using air as a working gas, under reduced pressure, followed by impregnation with a polymer binder characterized in that the preliminary processing of the fiberglass filler is carried out in the region of the negative glow of the abnormal glow discharge a low-temperature plasma is carried out wherein the continuous shift of working gas with maintaining the total pressure constant, and as polymeric binders used moistureproof polymeric binders having low levels of moisture absorption. 2. The method according to p. 1, characterized in that as a moisture-resistant polymer binders using binders based on polyester resins. 3. The method according to p. 1, characterized in that the processing of low-temperature plasma glow discharge with a current density of 0.1 mA / cm ² . 4. The method according to p. 1, characterized in that the change of the working gas is carried out with a flow rate of 50 ml / min.

Images