RU2323235C9 - Composition for preparing foam plastic - Google Patents

Abstract

FIELD: chemistry of polymers, chemical technology.

SUBSTANCE: composition for preparing foam plastic comprises the following components, mas. p. p.: soluble phenol-formaldehyde resin (novolacs), 20-40; phenol (resol) resin, 60-80; nitrile rubber, 20-40; blowing agent, 3-7; foam regulating agent, 1-20. As a foam regulator, products of processing alkylphenols with ethylene oxide can be used. Composition can comprise sulfur in the amount 0.2-0.5 mas. p. Invention provides preparing heat-stable, impact-strength foam materials not causing corrosion of nonferrous metals (copper, silver and their alloys) in direct contact and showing working capacity up to temperature 150°C. These materials can be used as heat-stable, vibration-proof materials in radiotechnical articles and articles having electric contacts made of nonferrous metals and alloys.

EFFECT: improved and valuable properties of composition.

3 cl, 2 tbl, 3 ex

Description

The invention relates to the field of aviation technology, mechanical engineering, namely to elastic, heat-resistant foams based on products of combining phenolic resins with elastomers that do not cause corrosion of non-ferrous metals (copper, silver and their alloys) in direct contact with them and are operable up to 150 ° C, which makes it possible to use them as heat-resistant, vibration-resistant materials in radio engineering parts and products having electrical contacts made of non-ferrous metals and alloys.

Known non-corrosive active foam, including phenolic resole resin, porophore and filler - still residue of lactam water regeneration (USSR copyright certificate No. 1781253).

Known foam, including phenolic resole resin, surfactant, blowing agent and catalyst (UK patent No. 2343181).

The disadvantages of the known foams are low values of specific impact strength and strength.

Known impact-resistant non-corrosive active polymer material, including rezol phenolic resin, novolac phenolic resin, nitrile rubber and filler fiberglass (US patent No. 5336723).

Known impact-resistant non-corrosive-active composite polymer material, including phenolic resole resin, nitrile or butadiene styrene elastomer, vulcanization accelerator, antioxidants (calcium and zinc stearates), sulfur and filler (inorganic and polymer powders) (US patent No. 4659758).

A disadvantage of the known materials is the high density (specific gravity), which is due to the content of a large amount of filler.

The closest analogue, taken as a prototype, is a composition for producing foam, including, by weight:

Phenolic resin 80-120 Nitrile rubber 10-30 Urotropin 8-12 Sulfur 0.2-0.5 Porophore 3-7 Phosphorus flame retardant urea shell 12-35.5

(RF patent No. 2213752).

The prototype foam has high impact resistance and reduced combustibility, but its disadvantage is increased corrosion activity to non-ferrous metals due to the presence of ammonia in its composition - the decomposition product of the urotropine hardener, which does not allow its use in aircraft instrumentation.

An object of the invention is the creation of non-corrosion-active non-ferrous foam, having increased impact resistance (impact strength).

The technical task is achieved by the fact that the proposed composition for the production of foam, including phenolic resin, nitrile rubber and porophore, which as a phenolic resin contains novolac phenolic resin and a resol phenolic resin and additionally contains a foam regulator in the following ratio of components, parts by weight:

Phenolic resin (novolac) 20-40 Phenolic resin (rezol) 60-80 Nitrile rubber 20-40 Porophore 3-7 Foam regulator 1-20

As a foam regulator, the composition advantageously contains the products of processing alkyl phenols with ethylene oxide.

In order to reduce the curing temperature, the composition may additionally contain sulfur in an amount of 0.2-0.5 wt.h.

The authors found that the introduction into the composition consisting of pre-combined novolac phenolic resin and nitrile rubber, an additional resol phenolic resin and a foam regulator allows mechanochemical combination of the resol resin with rubber, to obtain a block copolymer and to exclude from the composition of the composition hardener novolac resins - urotropin.

The initial rolled rezol-novolac composition is obtained by combining on the friction cooled rollers at a temperature of 30-50 ° C a rezol phenolic resin with a previously obtained rolled mixture of rubber and a mixture of novolac phenolic resin, foam regulator, porophore and, if necessary, sulfur.

Resin according to GOST 18694-80 is used as phenolic resins, for example, novolac grades SF-010, SF-014, resol resins, grades SF-342, SF-340, SF-381, etc.

As nitrile rubber, nitrile butadiene rubbers with a mass content of acrylic acid nitrile from 18 to 40% with a Defoe stiffness index of at least 800 Gs according to TU 38.3013-94 are used.

It is most preferable to use products of the treatment of alkyl phenols with ethylene oxide as a foam regulator, for example, Penta-483 foam regulator according to TU 2257-008-40245042.

Examples of implementation

Example 1

40 parts by weight novolac phenolic resin SF-010, 7 parts by weight porphore CHX3-57 (TU 113-03-365-82) and 20 parts by weight Penta-483 foam regulator (TU 2257-008-40245042) was mixed in a ball mill for 2-3 hours, after which the resulting mixture was combined with BNKS-40 nitrile rubber using the “dry-rolled” technology on cooled friction rollers. In the process of combining into the rolling composition was introduced 60 wt.h. resole resin SF-342. After rolling, a film was obtained, which was crushed, loaded into molds and heat treated at temperatures up to 170 ° C. Then the finished foam was removed from the mold.

The technology for preparing the composition of examples 2 and 3 is similar to example 1, but using 0.2 and 0.5 parts by weight sulfur, respectively.

The compositions of the compositions of examples 1-3 are shown in table 1, the properties of the proposed foam and foam prototype are shown in table 2. Corrosion tests were carried out according to GOST 9.902-81 with direct contact of the claimed material with metals (example 1 - copper, example 2 - brass) or in the gas phase (example 3 - silver).

The proposed foam is non-corrosive to non-ferrous metals. The impact strength of the proposed foam is on average 1.5-2 times higher than that of the foam - the prototype.

The use of the proposed foam and products from it will improve the reliability and service life of aircraft products.

Table 1 Name of components The composition according to examples, parts by weight Prototype one 2 3 Phenolic resin: 80-120 novolac 40 thirty twenty resol 60 70 80 Nitrile rubber thirty 40 twenty 10-30 Porophore 7 5 3 3-7 Sulfur - 0.2 0.5 0.2-0.5 Foam regulator twenty 10 one - Urotropin - - - 8-12 Urea-coated phosphorus flame retardant - - - 12-35.5

table 2 Name of properties Examples of the invention Prototype one 2 3 Impact strength, kJ / m ² 1.5-1.7 3.0-4.0 1.3-1.5 1.1-1.2 Operating temperature, ° С (linear shrinkage less than 1%) 120 150 120 120 Corrosion activity to copper, brass and silver Non-corrosive Non-corrosive Non-corrosive Corrosion

Claims (3)

1. The composition for producing foam, including phenolic resin, nitrile rubber and porophore, characterized in that as a phenolic resin it contains novolac phenolic resin and resol phenolic resin and additionally contains a foam regulator in the following ratio, wt.h .: Phenolic resin (novolac) 20-40 Phenolic resin (rezol) 60-80 Nitrile rubber 20-40 Porophore 3-7 Foam regulator 1-20 2. The composition for producing a foam according to claim 1, characterized in that as a foam regulator it contains the products of the treatment of alkyl phenols with ethylene oxide. 3. The composition for producing a foam according to claim 1, characterized in that it contains sulfur in an amount of 0.2-0.5 wt.h.