RU2802318C1 - Thermoset binder with high glass transition temperature - Google Patents

Abstract

FIELD: epoxy.

SUBSTANCE: invention relates to the development of a thermosetting epoxy binder processed into a polymer composite material (PCM) using injection technologies with a molding temperature of up to 150°C, for the manufacture of structures, including large-sized ones. Thermosetting binder comprises the following ratio of components, parts by weight: ED-22 - 10-80; N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane - 20-90; 2-methylimidazole - 1.0; resorcinol - 1.3; methylendic anhydride - 103.2-160.5.

EFFECT: increase in the glass transition temperature of the binder while maintaining a low viscosity of the binder.

2 tbl, 9 ex

Description

The invention relates to the development of a thermosetting epoxy binder processed into a polymer composite material (PCM) using injection technologies with a molding temperature of up to 150 ° C, for the manufacture of structures, including large ones, from polymer composite materials by vacuum infusion (VaRTM) or impregnation under pressure RTM (resin transfer molding) in the energy, construction, aviation, engineering, shipbuilding industries and other areas of technology.

For the manufacture of PCM by vacuum infusion, binders with low viscosity are required. The most common binders - epoxy resins, have a high viscosity. It is not always possible to reduce the viscosity by increasing the temperature of the binder, due to a decrease in the technological viability of the binder.

The most common binders - epoxy resins, have a viscosity that is an order of magnitude higher than these values. It is not always possible to lower the viscosity by increasing the temperature of the binder, especially when cold curing epoxy systems are used. To solve this problem, various solvents or active diluents are used.

The cheapest way to reduce the viscosity of binders is the introduction of solvents (acetone, alcohols, alcohol-acetone mixtures), while during the curing of the resin, the solvent evaporates, which causes additional technological problems associated with the removal of solvent vapors that remain in the composite material and worsen its physical properties. -mechanical properties.

The use of active diluents such as 1,4-butanediol diglycidyl ether (DEG-1) lowers the glass transition temperature of the binder.

A binder is known from the prior art (patent RU 2527086 C2, C08L 63/00; publ. 27.08.2014) based on epoxy resin ED-20, furfural acetone resin was used as a diluent, and triethanolaminotitanate was used as a hardener. The cured binder is characterized by a low glass transition temperature of about 130°C.

In the patent RU 2561085 C1, C08L 63/10, publ. On August 20, 2015, an epoxy binder composition was developed, including epoxy diano resin - ED-20, an anhydride-type hardener and a modifying additive - a polysaccharide derivative. The main disadvantage of this binder is the complexity of the technological process, as well as the low glass transition temperature - no more than 135°C, which does not provide an operating temperature of up to 120°C.

A thermosetting binder is known (patent RU 2666438 C1, C08L 63/00, publ 09/07/2018), including epoxy novolac resin brand UP-643, isomethyltetrahydrophthalic anhydride and a curing catalyst - tetrabutylammonium salt or neodecanoic acid dimethylhydrazide, or 4-phenylazo-N,N- dimethylaniline, or 1-(2-pyridylazo)-2-naphthol for the manufacture of prepregs using glass, carbon, organic fillers for the manufacture of high-strength heat-resistant polymer composite materials, for example, for products in aircraft and rocket building, shipbuilding, oil and gas and other areas industry.

The disadvantages of this invention are low viability - no more than 2-3 hours, as well as low glass transition temperature - no more than 172°C.

The prototype is an epoxy binder (RU 2749720 C1, C08L 63/00 publ 06/16/2021) including an epoxy resin based on bisphenol A, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, isomethyltetrahydrophthalic anhydride, 2 -methylimidazole and resorcinol.

The main disadvantage of the invention is the low glass transition temperature - no more than 185°C.

The technical objective of the invention is to create an epoxy binder with a higher glass transition temperature, processed by injection technology with a molding temperature of up to 150°C.

The technical result of the invention is to increase the glass transition temperature of the binder while maintaining a low viscosity of the binder.

To achieve the stated technical result, a thermosetting binder for the manufacture of polymer composite materials is proposed, containing an epoxy base, including an epoxy diano resin, a nitrogen-containing polyfunctional epoxy resin, which is used as N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane , 2-methylimidazole, resorcinol and differs in that instead of isomethyltetrahydrophthalic anhydride, methylendic anhydride is used in the following ratio, wt. hours:

ED-22 10-80 N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane 20-90 2-methylimidazole 1.0 resorcinol 1.3 methylenedic anhydride 103.2-160.5

The proposed binder can be used for the manufacture of PCM with a post-curing temperature of up to 150°C, has a dynamic viscosity of not more than 600 mPa⋅s at a processing temperature of 40°C and retains a technological viscosity of up to 600 mPa⋅for at least 5 hours, is suitable for the manufacture of products by injection methods which is especially important for the manufacture of large-sized products.

Examples of compositions and properties of the epoxy binder are presented in tables 1, 2.

Composition and preparation of a binder.

Example 1

Preparation of component A. The calculated amount (table 1) of nitrogen-containing polyfunctional epoxy resin N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, epoxy resin ED-22 is loaded into a laboratory mixer, then it is heated with stirring to temperature 100°C and enter resorcinol with vigorous stirring for 40 minutes. Then pour component A into a dry container.

Preparation of component B. Load the calculated amount (Table 1) of methylenedic anhydride and 2-methylimidazole into a clean and dry reactor. Turn on the stirrer and, stirring, heat up to a temperature of 90°C. Stir at this temperature for 60 minutes. The composition, the ratio of the components of the binder and its properties are shown in tables 1, 2.

Binder preparation. A portion of component A weighing 10.0 g and a portion of component B weighing 13 g are thoroughly mixed for 2 to 3 minutes in an evaporating cup at a temperature of 25°C.

Samples for mechanical testing of the cured matrix were prepared by casting in a metal tooling followed by curing according to the following regime: 110°C - 1 hour, 150°C - 4 hours.

The preparation of compositions according to examples 2-8 is carried out analogously to example 1, but with the ratios of the components indicated in table 1.

Table 1 - Compositions of the claimed thermosetting binder.

Component The composition of the binder, wt.h. 1 2 3 4 5 6 7 8 ED-22 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 N,N,N',N'-tetraglycidyl-4,4'- diaminodiphenylmethane 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 Methylendic anhydride 103.2 111.3 119.0 127.8 136 144.2 152.3 160.5 2-methylimidazole 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 resorcinol 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3

Table 2 - Properties of the claimed thermosetting binder

No. p / p Dynamic viscosity at 25 C, Pa s Glass transition temperature, С Strength
Bending MPa curing mode 1 1.11 163 105 110 °С - 1 hour
150 °С - 4 hours 2 0.99 172 110 3 0.88 181 110 4 0.75 188 112 5 0.68 190 110 6 0.59 193 115 7 0.50 197 112 8 0.42 201 115 Prototype 0.35 185 105

Table 2 shows that the claimed binder (composition No. 6-8) in comparison with the prototype has significantly higher glass transition temperatures up to 201 ° C (composition No. 8), thus, it can be possible to obtain a heat-resistant product from PCM with operating temperature up to 120°С.

Claims (2)

Thermosetting binder for the manufacture of polymer composite materials containing an epoxy base, including epoxy dianoic ED-22 and N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, and a hardener consisting of 2-methylimidazole, resorcinol, and characterized in that instead of isomethyltetrahydrophthalic anhydride contains methylendic anhydride in the following ratio, wt. hours: ED-22 10-80 N,N,N',N'- tetraglycidyl-4,4'-diaminodiphenylmethane 20-90 2-methylimidazole 1.0 Resorcinol 1.3 Methylendic anhydride 103.2-160.5