DE1569463C - Process for the production of molding compounds from phenol-formaldehyde condensates - Google Patents

Description

a) aqueous mixtures of phenol, formaldehyde, ammonia and alkali catalyst or their First plasticize precondensates with a part of wood flour and / or with calcium hydroxide Tung waste flour polycondensed,

b) then with gradual admixture if necessary the remaining amounts of filler, plasticizers, aqueous hexamethylenetetramine solution and the usual additives or dyes condensed to the end and

c) finally the homogenized moist mass by vacuum drying to the required level Raschig degree of flow plasticizes, cools, granulates, grinds and homogenizes.

extraction by hot pressing of cellulose with already condensed phenolic resin is known.

The object on which the present invention is based is to eliminate the disadvantages mentioned by developing a process which enables molding compounds with improved physical-mechanical properties to be produced while reducing the consumption of resin.
This problem has been solved in that one under

ίο Based on the known manufacturing process of molding compounds made of phenol-formaldehyde

^: Condensates by heating in an aqueous medium with the incorporation of fillers and other customary additives, such as hardeners, lubricants and colorants, and subsequent drying according to the invention

a) aqueous mixtures of phenol, formaldehyde, ammonia and alkali catalyst or their First plasticize precondensates with part of the wood flour and / or with calcium hydroxide Tung waste flour polycondensed,

b) then with, if necessary, gradually adding the remaining amounts of filler, plasticizers, aqueous hexamethylenetetramine solution and the usual additives or dyes to the end condensed and

c) finally the homogenized moist mass by vacuum drying to the required level Raschig degree of flow plasticizes, cools, granulates, grinds and homogenizes.

The invention relates to a process for the production of powdery molding compounds from phenol-formaldehyde condensates.

The condensation of synthetic resin components in the presence of filler, e.g. B. by immersing it in an excess of the finished thermosetting phenol-formaldehyde resin. The condensation is carried by means of a catalyst in admixture with the other ingredients useful at about 65 to 85 ⁰ C in 1.5 to 2.5 hours under it, the following parts by drying in vacuo, after which the reaction mass is finally dried and crushed. This process has the disadvantage that the tough, dough-like mass formed by the condensation of the resin with the total amount of filler inhibits the complete condensation, so that the resin formation is not controllable, whereby molding compounds with unstable properties are obtained; In addition, the process requires a considerable amount of manual labor and can neither be automated nor mechanized.

According to another known method, a mixture of the incompletely dried, another dried resin containing substantial amount of water with filler and the other ingredients and crushed; this process also requires significant manual labor as well as a large consumption of resin components.

It had already been recognized that this occurs when the filler is impregnated with a liquid phenol-formaldehyde mixture water present and occurring during the condensation hinders the production of desired products, consequently a condensation in anhydrous state was caused, whereby the resin formation after the hot pressing of the already formed structure took place. Also a fiber cardboard-the amount of additives and the length of time before their introduction is determined by the course conditions of the condensation process of resinifying agents definitely. As a rule, the filler is added in two stages, with about 20 to in the first stage 60 percent by weight, e.g. B. half of the filler amounts are incorporated.

The condensation process is ended when the last amounts of filler are mixed in together with the remaining components. The molding compound obtained is simultaneously plasticized and dried in vacuo. The new method is carried out with good mixing, which gives the required degree and speed the homogenization of the mass is ensured.

The new process for the production of molding compounds enables the consumption of resinifying agents reduce a whole range of physical-mechanical properties of the manufacturable products improve and carry out a continuous process of molding compound production, whereby the Conditions for the automation and mechanization of the manufacturing process are created.

In the method according to the invention, the following takes place:

a) When introducing the filler in portions in two or more stages, each one runs after the introduction Portion from a condensation stage in the aqueous medium; As a result, the reaction mass remains sufficiently liquid, hence the polycondensation processes run more completely and the entire process can be regulated better.

b) By using the vegetable fillers, wood flour and tung oil waste, of which the latter were previously subjected to a profound mechanical exploration, are

action processes reactive groups of these fillers with the formation of additional amounts Resin-forming products included.

c) The resin products formed in several stages are mixed with the remaining amount of filler and the other additives mixed and z. B. in a screw with simultaneous vacuum drying plasticized, creating favorable conditions for the most intimate penetration of the filler with the resin as well as for the mechanical-chemical processes between the resin and the reactive filler groups are created; the result becomes a lower Consumption of resin-forming substances and thus

: i achieved a higher profitability.

According to the following examples, the thermoactive molding materials produced were, for the purpose of testing their physical properties, which are important for their suitability for molding, in accordance with the standard regulations of the USSR under a pressure of 300 ± 50 kg / cm ² and a temperature of 180 ± 5 ° C into bars of 120- 15-10 mm or pressed into discs of 100 x 4 mm. In order to test the notched impact strength, pressed and non-indented test bars were subjected to impacts of 120-15-10 mm at a temperature of 180 ± 5 ° C. at a speed of 3.5 ± 0.1 m / sec. The Raschig flowability was determined on the unpressed materials.

example 1

The following raw materials were used in parts by weight:

Phenol 100

Formaldehyde 45

Ammonia 8

Stearin 1.5

Calcium stearate 1.5

Nigrosine 7

Hexamethylenetetramine 0.10

Wood flour 270

Water 375

The synthesis of the resole resin carried out in a customary manner by mixing the 100 parts by weight phenol with 125 parts by weight of a 36% formaldehyde solution (molar ratio 1: 1.4) condensed in the presence of 40 parts by weight of a 20% ammonia solution at 6O ⁰ C for 15 min;. The resulting 125 parts by weight of resole resin disclosed in the Ubbelohde tube on a dripping point of 68 ⁰ C.

Thereafter, half of the erforderliehen wood meal amount (135 parts by weight) added to the resin, followed by continued the condensation first 15 min. At 6O ⁰ C and then 15 min. At 9O ⁰ C. The resulting mass was mixed in a high-speed mixing screw with the remaining amount of wood flour and the other ingredients and the mixture was homogenized for 1 hour in a conventional mixing screw and then the moist mass in another screw device, in which the condensation ended with vigorous mixing, rubbing and simultaneous vacuum drying would.

The finished molding compound had the following properties:

Raschig flowability .. 160 mm

Hardness 30.3 kg / cm ²

Martens heat resistance 129 ° C.

The moldings produced therefrom had the following properties:

Average breakdown voltage 16.5 kV / mm

spec. electrical surface resistance 9.0 · 10 ¹² ohms

spec. electrical volume resistance 2 · 10 ¹² ohm · cm

Comparative experiments

The molding compound obtained was also compared with the molding compounds obtained according to K. Hultzsch, (Chemie der Phenolharze, 1950, p. 148, paragraph 3). For this purpose, the 125 parts by weight of resol resin obtained above were mixed in the manner indicated by Hultzsch with the above additives, first in a Werner-Pfleiderer mixer without heating, then for 7 minutes on heated rollers with friction at a temperature of 100 ° C of the hot roller and 80 ° C of the cold roller. The cooled and comminuted molding compound was pressed under a pressure of 300 kg / cm ² at 170 ° C. in 10 minutes each time to give moldings which, according to Hultzsch, had a resin content in relation to the filler content of 2: 3, ie 40% of the sum of the contain both main constituents, whereas the optimal values for the moldings according to the invention are 25: 54 and 31.7% -

The test of the shaped bodies showed in comparison with those obtained according to the invention according to Example 1 Sample the following values:

properties

Notched impact strength

Flexural Strength ..
Tear resistance ...
Compressive strength ..
Water absorption

After Hultzsch A I B

3.6
382
286
1228

0.22

4.2 501 303 1610

7.1 kg / cm / cm ² 708 kg / cm ² 400 kg / cm ²

1930 kg / cm ² 0.1 g / dm ²

Example 2

The following raw materials were used in parts by weight:

Tung bowls (converted to absolute dry weight) 110 to 150

crystalline phenol 80 to 110

techn. 40% formaldehyde solution 130 to 180

25% ammonia water 35 to 50

Lime converted to CaO 3 to 5

Wood flour, converted to abs.

Dry weight 110 to 150

Hexamethylenetetramine 11 to 15

Stearin 2.5 to 3.5

Nigrosine 8 to 9

Water 220 to 260

5 6

The total amount of the previously milled Tung flowability after

shells were mixed with the weight-wise Raschig 120 to 180 mm

Amount of water up to the dough-like consistency and let spec. Weight 1.35 to 1.40 g / cm ³

Swell for 1 hour; the swollen mass with lime water absorption was 0.06 to 0.09 g / dm ²

milk mixed and left to plasticize for 24 hours. 5

The resulting mass was poured into the melt.
Amount of formaldehyde and ammonia water ent- "- '

held and the 15 min. Was held ^{at 6O 0 C;} the latter notched impact strength 7.0 to 12.2 kg / cm / cm ²

Flexural strength was 650 to 950 kp / cm ^{2 again at the same temperature for 15 minutes}

get. The remaining dielectric strength ... 13 to 15 kV / mm was then added to the mixture
Remaining amount of formaldehyde and ammonia water was added and the joint condensation Example 3 was carried out
first 15 "min. at 60 ^° C. and then 20 min. at 85 bis
90 ⁰ C through. 15 Those listed below in parts by weight

To produce the molding compound, the starting materials were mixed according to Example 2:

Reaction mass in a high-speed mixer with phenol 100 wood flour

and the remaining ingredients, the mixture brought formaldehyde 64

into a combined two-screw machine and introduced ammonia 8th

in this the remaining condensation and the supplementary 20 j ^ kc _a O '8

mechanical-chemical processes such as plasti-tung cake 133

decoration, coloration and deep impregnation of the stearin i

Filler with resin with simultaneous vacuum drying calcium stearate 1

through. The product obtained was equivalent to Nierosin 7

moderately colored and resin-soaked mass, 25 hexamethylenetetramine '.'. '.'. '.'. '.'. '.'. '.'. '.'. '.'. '.'. '. 6th

those to cylidrons of 5 mm in diameter and 10 mm of water ■ 375

Length granulated and the cooled pro-wood flour granulated 133

product has been ground and homogenized. ''

The molding compound powder obtained had the following and is given a molding compound similar to that of Example 1

Features: 30 and 2.

Claims (1)

Claim: Process for the production of molding compounds from phenol-formaldehyde condensates by heating in an aqueous medium with the incorporation of fillers and other common additives, such as hardening agents, lubricants and coloring agents, and subsequent drying, characterized in that he