RU2323236C1 - Polymer binder for reinforced plastic - Google Patents

Abstract

FIELD: construction engineering; mechanical engineering; rocketry; space engineering for fire safety of articles.

SUBSTANCE: proposed binder contains components at the following ratio, parts by mass: epoxy-dian resin, 100; aniline-phenol-formaldehyde resin used as hardening agent, 80-100; urethane prepolymer used as modifying agent, 50-65; 3,3'-dichloro-4,4'-diamino-diphenyl methane used as hardening agent, 8-15; 2,2'-bis(3,5-dibromo hydroxyphenyl) propane, 120-140; solvent, 225-290. Used as solvent is alcohol-acetone mixture at mass ratio of alcohol to acetone of 1:1.

EFFECT: reduction of gelatinization time; production of prepreg on base of this binder at high life time and difficultly combustible plastic at high ultimate strength.

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Description

The invention relates to the field of polymer composite materials (PCM), and more particularly to reduced flammability fiberglass, and can be used in construction, mechanical engineering, space rocket technology, etc. regarding ensuring fire safety of products.

Known epoxy binder for reinforced plastics of reduced combustibility, containing tetra-glycidyl ether of 3,3'-dichloro-4,4'-diaminodiphenylmethane, hardener from the phosphazene group, initiator and organic solvent (ed. Certificate of the USSR No. 966101, IPC С08L 63/00, 1982). The oxygen index of the cured composition is 30%.

Known epoxy composition, including resorcinol diglycidyl ether and phosphonitrile anilide (ed. Certificate of the USSR No. 896032, IPC C08G 59/40, C08L 63/00, 1982). The oxygen index of the cured composition is 26-28%.

Other epoxy compositions are known using cyclic and linear chlorophosphazenes (US Pat. Nos. 3,641,193, NKI 260-830; 3,867,344; 3,933,738), Japanese application No. 50-40439. The oxygen index of the cured composition is 28-34%.

Known epoxy composition comprising 3,3'-dichloro-4,4'-diaminodiphenylmethane tetraglycidyl ether, hardener phosphonitrile anilide, initiator 1,2-bis (oxymethyl) carboran, modifier 3,5-di-tert- diethylene glycol ether butyl-4-hydroxyphenylpropionic acid and, if necessary, an organic solvent — an alcohol-acetone mixture (RF patent No. 2178430, С08L 63/00, 2002). The oxygen index of the cured composition is 39-45%.

Known epoxy binders for fiberglass low combustibility grades EDT-69N and EDG-69NU (RF patent No. 2028334, C08L 63/00, C08K 5/00, 1995). These binders contain an epoxy-diane resin modified with diethylene glycol diglycidyl ether, an epoxytriphenol resin, a bromine-containing epoxy resin and a hardener - bis- (N, N-dimethylcarbamidodiphenylmethane) in an alcohol-acetone solvent.

However, the gelation time of the binders EDT-69N and EDT-69NU at 120 ° C is ≈10 s. Hence, they cannot be used for the industrial production of pre-impregnated materials (prepregs) based on various reinforcing fibers, since a temperature of 100 to 120 ° C is required in the shaft of the impregnation machine to remove the solvent, and the residence time of the prepreg in the shaft is 15-17 minutes . It is quite understandable that during this time gelation of the binder will take place and the prepreg will be unsuitable for further processing by the method of “dry” winding or pressing.

Known binder for fiberglass (ed. Certificate of the Russian Federation No. 1657517 dated 02.22.91), including epoxy-diane resin, rezol phenol-formaldehyde resin and modifier - technical mixture of polysulfides in the following ratio of components, wt.%:

- epoxy-diane resin - 50-70;

- technical mixture of polysulfides - 0.5-6;

- rezol phenol-formaldehyde resin - the rest.

This binder is selected by us as an analog.

The disadvantages of all of the above binders are:

- fiberglass based on them are in accordance with GOST 12.1.044-89, clause 4.3 to the category of combustible materials (with a plastic thickness of not more than 7 mm);

- high cost due to the use of expensive and scarce epoxytriphenol (ETF), chlorine, nitrogen, and bromine-containing epoxies (UP-610, EHD, and UP-631) in binders;

- high cost and lack of industrial production of phosphazenes.

The closest technical solution for the combination of the main essential features and the achieved technical result is a binder for reinforced plastics (RF patent No. 2215759, С08L 63/00, 2003) - a prototype comprising epoxytriphenol resin - 100, anilinophenol-formaldehyde resin (hardener) - 35-60, low molecular weight butadiene-acrylonitrile rubber with terminal carboxyl groups - 10-50, bis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propyl] sulfide (curing accelerator and structure former) - 1-5, alcohol-acetone mixture (mass with alcohol and acetone ratio of 1: 1) - 90-200.

The disadvantages of this binder include:

- the presence in the composition of scarce and relatively expensive components: epoxytriphenol resin and bis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propyl] sulfide - a product under the brand name "SO-3" - TU 88-15326 -01-90;

- fiberglass based on it (with sample thickness up to 7 mm) according to GOST 12.1.044-89, clause 4.3 refers to the category of combustible materials;

- insufficient viability of the prepregs when they are stored in workshop conditions at a temperature of 15-30 ° C.

The viability of binders based on epoxy, epoxyphenol and other binders is characterized, first of all, by the time during which the prepreg during processing (unwinding and cutting rolls, etc.) does not crumble, and during bending does not peel the binder.

The task is ensured by the fact that the epoxy binder for reinforced plastics, including epoxy resin, hardener - anilinophenol-formaldehyde resin, modifier, curing accelerator and solvent - alcohol-acetone mixture with a mass ratio of alcohol and acetone 1: 1 additionally contains 2,2'-bis- (3 , 5-di-bromo-4-hydroxyphenyl) propane, as an epoxy resin, an epoxy-diane resin, a urethane prepolymer as a modifier, and 3,3'-dichloro-4,4'-diaminodiphenylmethane as a curing accelerator at after the blowing ratio of the components of the binder, parts by weight:

epoxy diane resin one hundred anilinophenol formaldehyde resin 80-100 2,2'-bis- (3,5-di-bromo-4-hydroxyphenyl) propane 120-140 urethane prepolymer 50-65 3,3'-dichloro-4,4'-diaminodiphenylmethane 8-15 alcohol-acetone mixture (with mass the ratio of alcohol and acetone 1: 1) 225-290

The distinctive features of the proposed epoxy binder for reinforced plastics are the following features:

- additional introduction of 2,2'-bis- (3,5-di-bromo-4-hydroxyphenyl) propane as a flame retardant;

- introduction of an inexpensive and commercially available epoxy-diane resin instead of epoxytriphenol resin (GOST 10587-84);

- the introduction of a hardener - anilinophenol-formaldehyde resin in other quantitative limits than in the prototype;

- introduction of a urethane prepolymer as a modifier;

- the introduction as an accelerator (approval and at the same time a flame retardant that increases the fire resistance of the polymer (reinforced plastic) - 3,3'-dichloro-4,4'-diaminodiphenylmethane.

Resole anilinophenol formaldehyde resin of the SF-340A or SF-341A grades (GOST 18694-80) is not only an active hardener of epoxy-diane resin, but along with the bromine-chlorine-containing components of the binder additionally provides high fire resistance of the epoxy polymer (plastic).

2,2'-bis- (3,5-di-bromo-4-hydroxyphenyl) propane (tetrabromodiphenylolpropane) is a white to light brown powder, readily soluble in alcohol and acetone. Melting point - at least 176 ° C. The mass fraction of bound bromine is at least 58%.

The SKU-PFL-100 urethane prepolymer (TU 38-103137-78) is the product of the interaction of polyfurite with isocyanate (2,4-toluene diisocyanate). Viscosity at 25 ° С - 7.5-13 Pa · s (at the level of epoxy-diane resin ED-22), mass fraction of NCO-groups,% - 5.3-6.4.

A urethane prepolymer is introduced into the binder in order to reduce the stiffness of the prepregs.

3,3'-dichloro-4,4'-diaminodiphenylmethane (Dia. X) - TU 6-14-980-84 is involved in the curing reactions of the epoxy-diane resin and the urethane prepolymer. It is a powder or granules of a yellowish-gray color with a melting point of at least 103 ° C and with a content of diazotizing substances of at least 98%.

As a solvent, as in the prototype, a cheap, affordable and volatile solvent - alcohol-acetone mixture (with a mass ratio of alcohol and acetone of 1: 1) was selected. Based on the conditions of good solubility of all components of the binder from alcohols, the most affordable and environmentally friendly ones were selected - ethyl or isopropyl.

These distinctive essential features are new, since their use in the proposed combination, quantitative and qualitative ratio in the prior art, analogue and prototype have not been found, which allows us to characterize the proposed epoxy binder for reinforced plastics according to the criterion of "novelty".

A single set of new essential features with common known essential features allows us to solve the problem and achieve a new technical result, which characterizes the proposed epoxy binder significant differences from the prior art, analog and prototype.

The new epoxy binder for reinforced plastics is the result of scientific and experimental research and creative contribution, obtained without the use of any standard developments, instructions or recommendations in the field of plastics processing technology, based on the use of a new concept for its preparation, it is not obvious to specialists and is characterized by compliance with the criterion "Inventive step".

A method of obtaining a patentable epoxy binder, prepregs and plastics based on it is as follows.

A. Preparation of an epoxy binder.

A binder in large (60-400 kg) quantities is prepared in a mixer with a mixer (anchor or anchor-blade type), with a hatch for loading components and a lower drain cock. A small amount of binder is prepared in any suitable container with manual mixing. In order to accelerate the dissolution of the anilinophenol formaldehyde resin, it is preliminarily crushed in a crusher, mill, or roller to a particle size of no more than 2 mm.

The calculated amount of acetone (according to the recipe) is poured into the mixer, then the calculated quantities of crushed anilinophenol-formaldehyde resin, tetrabromodiphenylolpropane and Diameter X are loaded into the mixer and the mixture is stirred (at room temperature) until a homogeneous solution is obtained (approximately 1-1.5 hours). Then, the calculated amount of ethyl or isopropyl alcohol and the epoxy-diane resin and urethane prepolymer warmed up to the flowing state are loaded into the mixer with stirring, after which the mixture is continued to mix for another 1-1.5 hours. The ready-to-use epoxy binder is poured into appropriate containers.

Depending on the requirements for a particular impregnated material, in the process of impregnation, the density of the binder is adjusted by dilution directly in the bath of the impregnating machine. Typically, the concentration of the binder solution is in the range of 55-65 wt.%.

B. Obtaining pre-impregnated materials.

For a comparative assessment of the strength characteristics of fiberglass on the claimed binder, analogue and prototype, structural fiberglass ТСУ 8/3-ВМ-78 (ТУ 6-11-292-84) was impregnated on an industrial impregnation machine.

Impregnation Parameters:

- impregnation speed, m / min - 1-1.5;

- temperature in the mine, ° C - 110-120.

The impregnated fabric had the following characteristics:

- mass fraction of volatiles,% - 1 ± 0.4;

- mass fraction of soluble substances,% - 96 ± 2;

- mass fraction of binder,% - 30 ± 2.

B. Research Methods.

Currently, a variety of indicators are used to evaluate combustibility: mass loss, oxygen index (CI), combustibility index by calorimetry method, burning resistance category of plastics (GOST 28157-89), combustibility of polymeric materials according to GOST 12.1.044-89 (p .4.3, OTM device) and the combustibility assessment of building materials in accordance with GOST 30244-94.

We have chosen a method for assessing the combustibility of polymeric materials in accordance with GOST 12.1.044-89 (clause 4.3), which is used by the head institutes of the Ministry of Internal Affairs (MES) to test the combustibility and issue fire safety certificates for all polymeric materials (except for construction materials).

When testing with an OTM device, the dimensions of the samples are (150 ± 3) × (60 ± 1) mm, and the thickness is not more than 30 mm. Given that the thickness of the test samples is essential, for a comparative assessment of the combustibility of samples from different materials, the thickness of the samples should be the same.

According to this method, materials are classified into slow-burning and combustible. Flammable materials, depending on the time (τ) of achievement during testing the maximum temperature (t _max ) are divided into: highly flammable (τ <0.5 min), medium flammability (0.5≤τ≤4 min) and low flammability (τ> 4 min ) During the test - 5 min (the time of the gas burner) according to the value of the maximum temperature increment (Δt _max = t _max -200 ° C) and weight loss (Δm) during combustion, the materials are classified into:

- hardly combustible - Δt _max <60 ° C and Δm <60%;

- combustible - Δt _max ≥60 ° C and Δm≥60%.

Flammability samples were cut mechanically from extruded plates.

A prepreg based on TR-07 roving fiberglass (≈0.7 mm thick) was impregnated with binders of different formulation composition, including binders selected as an analogue (example 1) and prototype (example 2) manually, using a brush, providing binder deposit (30 ± 2) wt.%. Drying was carried out in a heating cabinet to a mass fraction of volatiles of not more than 1% and a mass fraction of soluble not less than 96%. Plate pressing mode: specific pressure - 10-15 kgf / cm ² , pressing temperature - (160 ± 5) ° С, holding time - 40 min per 1 mm of thickness.

The thickness of the test samples was 3.5-4 mm. The viability of the prepreg at a storage temperature of 15-30 ° C was evaluated by the time during which the elasticity of the prepreg was maintained, and the mass fraction of soluble> 90%.

The gelatinization time of the binders was determined using a polymerization plate, as described in GOST 901-78.

Physical and mechanical tests of fiberglass samples were carried out according to OST 3-4791-81, OST 3-4792-81, etc.

Fiberglass plates made of prepreg based on TSU 8/3-VM-78 structural fiberglass were pressed at a specific pressure of 10 kgf / cm ² and stepwise heating from 20 to 160 ° C with a shutter speed of 0.5-1 hour per 1 mm of thickness.

Example 1 (analog).

The calculated amount of the alcohol-acetone mixture is poured into the container (mixer), and then, with the stirrer working, the ED-20 epoxy-diane resin and the technical mixture of polysulfides (TAB) are heated to a fluid state. The mixture is stirred (at room temperature) until a homogeneous solution (approximately 1-1.5 hours). Then, with the stirrer working, the calculated amount of the rezol phenol-formaldehyde resin - LBS-16 bakelite varnish (in the form of a 70% solution in ethanol) is loaded and the mixture is continued to mix for another 0.5-1 hour. The binder is ready to use.

Example 2 (prototype).

The calculated amount (according to the recipe) of the amount of acetone is poured into the container (mixer), then the calculated amount of the crushed anilinophenol-formaldehyde resin (SF-340A or SF-341A) and the powdered product CO-3 are loaded and the mixture is mixed at room temperature until a homogeneous solution is obtained ( approximately 1-1.5 hours). Then, the calculated amount of alcohol (ethyl or isopropyl) and the epoxytriphenol resin (ETF) and low molecular weight rubber SKN-10KTRA or SKN-30KTRA heated to a fluid state are loaded into the mixer with the mixer running, after which they continue to mix for another 1-1.5 hours. Ready-to-use binder is poured into appropriate containers.

Examples 3-8.

The cooking procedure is described above (see section A).

Examples 3-5.

The content of anilinophenol formaldehyde resin, tetrabromodiphenylolpropane, urethane prepolymer, Diameter X and solvent meets the declared limits.

Example 6

Instead of ethyl alcohol, isopropyl alcohol was taken.

Examples 7, 8.

The content of anilinophenol-formaldehyde resin, tetrabromodiphenylolpropane, urethane prepolymer, Diameter X and solvent above and below the stated limits.

The solvent content in the claimed range (examples 3-5) is selected based on the concentration of binders 55-65% (as already noted above). In the process of impregnation, the solvent is completely removed and in the impregnated materials (prepregs) the content of volatiles does not exceed (1 ± 0.4)% by weight, and in the finished plastic there is no solvent.

The quantitative limits of the binder ingredients were set based on the following conditions:

- the combustibility category of fiberglass according to GOST 12.1.044-89 (clause 4.3) with a sample thickness of not more than 4 mm - slow-burning:

- the viability of the prepreg during storage in workshop conditions (15-30 ° C) - at least 2 months;

- gel time is not higher than that of the analogue and prototype;

- the main strength characteristics (at 20 ° C) are higher than that of the analogue and prototype.

When the hardener, modifier, flame retardant (tetrabromodiphenylolpropane) and curing accelerator are contained in the binder in a smaller or larger amount than within the stated limits, the main objective of the invention cannot be achieved - to obtain low-combustible fiberglass with a test specimen thickness of ≈4 mm. Fiberglass according to example 1 (analog) and example 2 (prototype) belongs to the category of combustible, medium flammability.

The viability of the prepreg on the claimed binder is also significantly superior to similar prepregs based on the binder according to example 1 (analog) and example 2 (prototype).

The gelation time of the claimed binder (examples 3-5) is 3.5-4 minutes at 160 ° C, analogue - 6 minutes, the prototype - 5.5 minutes

Table Examples The composition of the binder, wt.h Flammability category Gelatinization time at 160 ° С, min The viability of the prepreg at 15-30 ° C, day The tensile strength of fiberglass at 20 ° C, kgf / mm ² bending compression chipping one ED-20 70 Combustible, medium 6.0 thirty 40 25 2,5 (analog) Rezol FFS thirty flammability TAB modifier 6 2 ETF one hundred Combustible, medium 5.5 45 43 28 3.0 (prototype) AFF 45 flammability SKN-30KTRA thirty SO-3 3 Alcohol Acetone mixture (1: 1) 120 3 ED-20 one hundred Incombustible 4.0 60 55 40 3,7 (claimed AFF 80 limits) TBDFP 120 SKU-PFL-100 fifty Diameter x 8 Alcohol Acetone mixture (1: 1) 290 four ED-20 one hundred Incombustible 4.0 70 fifty 35 3,5 (claimed AFF 90 limits) TBDFP 130 SKU-PFL-100 55 Diameter x 10 Alcohol Acetone mixture (1: 1) 255 5 ED-20 one hundred Incombustible 3,5 75 45 thirty 3.3 (claimed AFF one hundred limits) TBDFP 140 SKU-PFL-100 65 Diameter x fifteen Alcohol Acetone mixture (1: 1) 225 6 ED-20 one hundred Incombustible 3.0 75 fifty 35 3.2 (claimed AFF 90 limits) TBDFP 130 SKU-PFL-100 55 Diameter x 10 Isopropyl alcohol and acetone (1: 1) 255 7 ED-20 one hundred Combustible, hard 4,5 fifty 40 28 2.2 (above AFF 110 flammable claimed TBDFP 150 limits) SKU-PFL-100 70 Diameter x 12 Alcohol Acetone mixture (1: 1) 145 8 ED-20 one hundred Combustible, medium 5,0 45 35 25 1.8 (below AFF 70 flammability claimed TBDFP 110 limits) SKU-PFL-100 45 Diameter x 8 Alcohol Acetone mixture (1: 1) 335

According to the basic strength characteristics of fiberglass on the claimed binder surpasses the analogue and prototype.

Thus, the new technical solution together with the proposed essential features when implemented in an epoxy binder for reinforced plastics and products based on them gives a new positive effect that meets the criterion of "industrial applicability", i.e. level of invention.

There may be various versions of the epoxy binder in composition and quantitative ratio of components, if this does not go beyond the scope of the technical solution set forth in the claims.

Claims (1)

An epoxy binder for reinforced plastics, including an epoxy resin, a hardener - anilinophenol formaldehyde resin, a modifier, a curing accelerator and a solvent - alcohol-acetone mixture with a mass ratio of alcohol and acetone of 1: 1, characterized in that it additionally contains 2,2'-bis- (3 , 5-di-bromo-4-hydroxyphenyl) propane, as an epoxy resin - an epoxy-diane resin, as a modifier - a urethane prepolymer and as a curing accelerator - 3,3'-dichloro-4,4'-diaminodiphenylmethane at the following relation binder components, parts by weight .:  epoxy diane resin  one hundred  anilinophenol formaldehyde resin  80-100  2,2'-bis- (3,5-di-bromo-4-hydroxyphenyl) propane  120-140  urethane prepolymer  50-65  3,3'-dichloro-4,4'-diaminodiphenylmethane  8-15  alcohol-acetone mixture (with a mass ratio of alcohol and acetone 1: 1)  225-290