SU757547A1 - Method of preparing phenolformaldehyde resin - Google Patents

Description

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The present invention relates to the field of production of phenolic resins, in particular a modified phenol-formaldehyde resin, which can be used in

binder in the manufacture of asbestos-friction materials.

A method of obtaining modified phenol-formaldehyde resins [ί}, including the condensation of phenol and formaldehyde in the presence of an alkaline catalyst.

Carboxylic acids belonging to certain classes of the compound are used as modifying agents in this method! aliphatic acids (oxalic, adipic, etc.), aromatic (salicylic, phthalic, etc.).

Modifying agents are used mainly to improve the physicomechanical properties of resins, namely hardness, to obtain colored resins.

For modified phenol-formaldehyde resins, used as a binder for the production of friction materials, there are increased requirements for heat resistance. It is known that the increase in thermo2

durability is promoted by the modification of phenolic resins with substances that incorporate linear chains, for example, vegetable oils, with a base.

A method of obtaining a solid rezol resin by condensation of phenol and formaldehyde in the presence of ammonia as a catalyst

0 followed by modification with rosin E ^{1 2} ] ·

Rosin is a complex substance and the composition is a mixture of isomeric rosin acids sos5 tava C _2o H _zo 0 _2. The use of rosin results in a low molecular weight resin with insufficient heat resistance (coke number 26-31%).

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In addition, the use of rosin in the production of resin causes pollution of the equipment, which greatly complicates the technology for manufacturing.

The purpose of the invention

is to increase heat resistance

and thermal stability of phenol-formaldehyde resin and the creation of waste-free production.

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This is achieved by the fact that in the method including the condensation of phenol, aldehyde-containing component and modifying agent, a mixture of isopropylfluorene and isopropylfluorene carboxylic acids in a ratio of 1: 1-2 in the amount of 20-35 parts by weight per 100 parts phenol, and as the aldehyde-containing component take paraform in the amount of 50-55 parts by weight per 100 parts by weight of phenol.

The raw material for the production of the modifiers used is fluorene, obtained from coal tar, the production of which reaches 15–16 million tons per year. The method for producing acids is not complicated, a production process has now been developed and prototypes have been developed. ·

The use of paraform as an aldehyde raw material makes it possible to create waste-free production of modified phenol-formaldehyde resin.

Example. 100 weight.h phenol,

.50-55 weight.h paraform, 1-2.5 weight.h

ammonia (in the form of 25% ammonia

water) and 20-35 parts by weight of a mixture of monobasic acids based on isopropylfluo, ren (60% isopropylfluorenecarboxylic and 40% isopropylfluorenic acids) are loaded into a reactor equipped with a stirrer, a thermometer and a refrigerator. The mixture is heated to boiling and

, conduct condensation for ^ιυ 60 min. Drying is carried out under vacuum to

achieve the time of gelatinization of the resin 60-120 seconds at a temperature of 150 ° C.

15 The obtained resin is a brown solid, well soluble in alcohol.

In tab. 1 presents the data

20 characterizing the properties of the resin obtained by the proposed method (example 1), in comparison with the properties of the resin obtained by a known method (example 2).

25 Table!

The name of indicators Example 1 Example 2 The content of free phenol,% 6.30-9.33 9.1 Moisture contents,% 1.6-2.2 2.1 The content of methyl groups,% 15-15 13.2 Gel time, sec 118-75 81 Dropping temperature 88-80 82 The viscosity of the 50% aqueous solution of resin in alcohol, SP 105-218 194 Coke residue,% 48.5-44.8 31 Heat resistant resin ι: a) temperature 50% mass loss, ’s 600-580 550 b) mass loss at a temperature, in%; 300 ° C 12-12,5 13 500 ° C 27-27.3 38 700 ° C 65-74.6 93

The heat resistance of the resin is characterized by a coke residue (for a known resin, the coke residue is 31, for the proposed resin 44-48).

The more coke residue, the more heat-resistant resin.

In addition, the heat resistance of the resin can be estimated using a thermogravimetric method of analysis, which allows you to record ¹ loss in weight at different temperatures.

Weight loss in a known resin

. at a temperature of 500 ° С 38%, in the offered one - 27%; at a temperature

'700 ° C - 93% of the known resin,

proposed - 65-74%.

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Thus, heat resistance

the proposed resin at high temperatures (500-700 ° C) significantly

higher than the famous.

The resin obtained by the proposed method was tested as 5 binding asbestos friction materials in the recipe material

FC-24A in the following ratio of components, wt.%:

Asbestos 40 10

Barite 35

Resin 2 5

In tab. 2 shows the results of testing materials made on the basis of the resin obtained by the proposed method (example 1) in comparison with the materials based on the resin obtained in a known manner (example 2).

Table 2 20

Name of the indicator Example one Example 2 95 Impact strength, kgf * cm / cm ² 10.2 eight Destructive stress thirty static bending life, kgf / cm ² 352.8 319 2 Hardness, kgf / cm 3025 3007 35 Friction coefficient 0.474 0.469 Linear wear when tested on a friction type machine MI-1, mm / hour 8.1 15.5 40

 Using the proposed method allows to create a phenol-formaldehyde resin, which has a high heat resistance at high temperatures (500-700 ° C).

In addition, the proposed method is non-waste.

At present, industrial- and titanium phenol-formaldehyde resins are obtained using formalin as an aldehyde-containing raw material, which is a 37% formaldehyde solution in water. Water after condensation is removed from the reactor; it contains up to 7% phenol and 5% formaldehyde. Purification of this water is a time consuming and costly process. When using paraform as an aldehyde raw material, resinous waters are practically absent.

Using the proposed modifier instead of gum rosin will give the national economy an economic effect of 50,000 rubles. with the release of resin in the amount of 1200 t / g. Increased heat resistance of the resin allows you to create a material with improved physico-mechanical and operational properties, it will also give the national economy an additional economic effect by extending the service life of the products.

Claims (1)

Claim A method of obtaining a phenol-formaldehyde resin, including the condensation of phenol, an aldehyde-containing component and a modifying agent in the presence of an alkaline catalyst, characterized in that, in order to increase the heat resistance and thermal stability of the resins, a mixture of isopropylfluoro-and isopropylfluorene-carboxylic acids is taken in a ratio of 1: 1-2 in the amount of 20-35 parts by weight per 100 parts by weight of phenol, and as aldehyde containing the component - paraforms in the amount of 50-55 parts by weight per 100 parts by weight of phenol.