CS258209B1 - Modifiers for blowing agents - Google Patents

Abstract

Use of urea-formaldehyde condensates surface activated powder water insoluble inorganic substances characterized ash content of 1.2 to 92.3% by weight, as activators in manufacture and / or application of 1,5-methano-3,7-dinitroso-based blowing agents -1,3,5,7-tetraazacycloctane and / or azodicarboxamide in an amount of 5 to 65 wt. on weight! the resulting mixture. Suitable especially for production and application of rubber blowing agents.

Description

The invention relates to the use of urea-formaldehyde condensates of surface-activated water-insoluble inorganic substances as modifiers in the production and / or application of blowing agents based on 1,5-methano-3,7-dinitroso-1,3,5,7-tetraazacycloctocane and / or azodicarboxamide.

The blowing agents based on 1,5-methano-3,7-dinitroso-1,3,5,7-tetraazacyclooctane (DNPT), depending on the requirements of the rubber and plastics industries, contain about 40 to 90 wt. active ingredient. The concentrated blowing agent contains an amount of mineral oil or other phlegmatizing agent to reduce dustiness and impact sensitivity. Increased safety in transport and storage, while improving the porous structure of the products to be treated, is achieved by controlling the active ingredient with a neutral inorganic additive such as kaolin, micronized limestone, hydrated borax, sodium sulfate, micronized zeolite, and the like.

In order to eliminate the unpleasant odor produced by DNPT thermolysis in the process of brewing, in particular rubber products, deodorizing agents such as methylolurea with methylenebismurea, respectively, are added to the blowing agents. at the same time (glycol, glycerin and the like), or biuret, water-insoluble urea derivatives, in particular uncrosslinked water-insoluble urea-formaldehyde condensates, and others.

When applying blowing agents based on azodicarboxamide, especially in the rubber industry, or when gassing ethylene-vinyl acetate copolymers, it is desired to lower the decomposition temperature of the azo compound, i.e. to activate it. This is accomplished by the addition of various activators, in particular zinc and other metal salts, hexamethylene tetramine, biuret, but also water-insoluble urea derivatives or 1,5-methano-3,7-dinitroso-1,3,5,7-tetraazacyclooctane (DNPT).

The use of water-insoluble urea derivatives themselves, in particular urea-formaldehyde condensates, as blowing agent modifiers in view of rising raw material and energy prices for their synthesis shows what once less advantageous; partial substitution with available and fasting micronized minerals (limestone, kaolin, zeolites) is a certain solution in terms of technical-safety parameters and nucleation properties of the resulting blowing agents, but in the case of a mixture based on 1,5-methano-3,7-dinitroso-l 3,5,7-tetraazacyclooctane has a negative effect on the deodorant properties of the blowing agent due to the reduction of the overall surface area of the deodorizing agent particles with the related substitution.

In addition, with the progressive depletion of deposits of high-quality, light shades of minerals (kaolin, zeolites, limestone), the question of economic utilization of less attractive, mostly dark-colored minerals as fillers in rubber, plastics and for example is coming to the forefront. in the paper industry; need not be emphasized here that such fillers and modifiers cannot be used in white and light shades of products exchanged by industry and that this problem cannot be solved only by mechanical blends of dark-colored micronized minerals with white pigments such as e.g. and water-insoluble urea-formaldehyde condensates.

The above-mentioned and other drawbacks are solved by the process according to the invention which consists in using urea-formaldehyde condensates of surface-activated water-insoluble inorganic substances such as kaolin, zeolites, carbonates or sulphates of alkaline earth elements and the like, characterized by an ash content of 1.2-92.3%. % as a modifier in the production and / or application of blowing agents based on 1,5-methano-3,7-dinitroso-1,3,5,7-tetraazacycloctocane and / or azodicarboxamide in an amount of 5 to 65 wt. to the weight of the resulting mixture.

An advantage of the process according to the invention is the easy availability of surface-activated water-insoluble inorganic substances consisting in the acid-catalyzed condensation of urea with formaldehyde in the presence of a suspension of that inorganic substance in the reaction mixture. Because of the high hiding power of water-insoluble urea-formaldehyde condensates, less valuable, dark colored minerals can be utilized, which is another advantage of the process of the present invention.

By suitably selecting the content of the inorganic water-insoluble substance in its surface-urea-formaldehyde condensate activated analog, it is possible, e.g. prepare deodorant, respectively. an activating agent having the same efficiency in this respect as the urea-formaldehyde condensate itself, which is another advantage of the present invention, since it is possible to realize the savings of formaldehyde and urea in the synthesis of the modifier. .

The use of urea-formaldehyde condensates of surface-activated powdered water-insoluble inorganic substances according to the invention as blowing agent modifiers has not been described in the literature. It is illustrated by the following examples, which in no way exclude the possible variability of the process according to the invention.

Example 1

Using the procedure for the synthesis of urea-formaldehyde condensates according to U.S. Pat. of the author's certificate no. 227 901 with the addition of 30% aqueous rubber kaolin to the reaction mixture prior to synthesis and drying of the resulting activated kaolin slurry in a spray dryer having an inlet temperature of 135 ° C to 140 ° C and an outlet temperature of 98 ° C to 103 ° C. kaolin with a content of 2.9 wt. % water, 0.267 wt. % methylol and 50.73 wt. ash.

From this kaolin and technical 1,5-methano-3,7-dinitroso-1,3,5,7-tetraazacyclooctane (DNPT) a mixture containing 60 wt. DNPT and 40 wt. activated kaolin.

This powder mixture does not change its consistency after storage for three months at 20-24 ° C. In terms of application as a rubber blowing agent, this composition has the same performance properties as an analogous composition containing only urea-formaldehyde condensates according to the invention. of the author's certificate no. 227 901 (cf. author's certificate no. 227 904). The thermal stability of the composition according to this example is presented in Table no. 1 of Example 5. '

Example 2

A powder blend containing 80% by weight of azodicarboxamide (ACD) and the surface-activated kaolin of Example 1 is prepared. % azodicarboxamide and 20 wt. activated kaolin.

From the thermal stability of this mixture (see Table 1 in Example 5), it can be seen that the ACD is so activated by the addition of the kaolin of Example 1 that it can be used to lighten e.g. rubber-based outsole materials (at the level of conventional DNTP blowing agents).

Example 3

Using the procedure for the synthesis of urea-formaldehyde condensates. pod čs. of the author's certificate no. 230 015 with the addition of 30% by weight of rubber kaolin in water to the reaction mixture before the synthesis and further processing, as in Example 1, resulted in a powdered white surface-activated kaolin containing 2.96% by weight. water, 0/548 wt% · methylol groups and 49.86 wt% water; ash (a hydrophilized form of activated kaolin).

From this kaolin and 1,5-methano-3,7-dinirose-1,3,5,7-tetraazacyclooctane as in Example 1, a mixture containing 40 wt. of activated kaolin having similar properties and wear to the composition of Example 1. The thermal stability of this composition is presented in Table 1. 1 of Example 5.

attaches

From the azodicarboxamide of Example 2 and the surface-activated kaolin of Example 3, a mixture containing 80 wt. % azodicarboxamide and 20 wt. activated kaolin.

As can be seen from the overview of thermal stability in Table no. In Example 5, the azodicarboxamide is somewhat more activated than in the mixture of Example 2.

Example 5

By using a non-isothermal differential thermal analase (DTA) operating at a linear temperature rise rate of 5 ° C / min, a measuring range of 1 mV per scale scale with a weight of about 50 mg of the sample is for the mixtures of Examples 1 to 4 as 5-methano-3,7-dinitroso-1,3,5,7-tetraazacyclooctane (DNPT) and azodicarboxamide (ACD) Specified origins and other thermal decomposition characteristics; results are presented in Table no. First

Method of thermal explosion according to H. Henkin and R. McGill (Ind. Eng. Chem. 1952,

44, No. 06, 1391-1395), the induction periods are specified for the mixtures of Examples 1 to 4 as well as for the starting DNPT and ADC; for DNPT and mixtures containing it in the temperature range 190 to 210 ° C, for ADC and mixtures containing it in the temperature range 210 to 250 ° C. From the values thus obtained, the activation energies of the explosion E and the extrapolated induction periods Tau for 150 and 190 ° C are calculated. Corresponding results are presented in Table no. First

T a b at 1 k and no. 1 review of the results of the thermostability measurements of Example 5 sample (Mixture) Extracts from DTA method thermal explosion Exothermic decomposition beginning (° C) first peak <° C) flash point (° C) E (kJ.mol) ^Tau 150 ^Tau 190 DNPT default according to 139.1 169.7 185.3 58,94 213.8 50.3 kladu 1 136.4 171.1 183.1 56.88 199.0 49.2 according to example 3 135.8 167.6 182.2 52,98 174.5 47.5 ADC Default according to 161.5 - 193.0 57.68 341.0 82.7 kladu 2 159.5 - 195.0 47,91 231.7 71.4 according to Example 4 158.7 - 191.5 45,28 186.5 61.3

Notes: Tau ^ jg “extrapolated induction periods for 150 ° C;

^Tau 190 ⁼ P ^{re DN? T and} 3 ^e h ° mixtures averaged, for ADC and its mixtures, extrapolated induction periods at 190 ° C;

examples

Using the procedure for the synthesis of urea-formaldehyde condensers according to U.S. Pat. of the author's certificate no. 227 901 and the addition of a 25% aqueous suspension of micronized limestone (natural calcium carbonate) to the reaction mixture prior to the synthesis itself is a further treatment, as in Example 1, to obtain surface-activated limestone containing 2.17 wt. water, 0.086 wt. % methylol and 92.3 wt. ash.

From this activated limestone, technical 1,5-methano-3,7-dinitroso-1,3,5,7-tetraazacyclooctane (DNPT), a mixed triaryl phosphate based on isopropylized triphenyl phosphate derivatives, a free-flowing composition of (wt.%) Is prepared. 30% DNPT, 60% activated limestone and 10% mixed triaryl phosphate.

This mixture does not show signs of agglomeration after 3 months storage at 20-25 ° C. Using DTA as in Example 5, it has an onset of exothermic decomposition at 141.8 ° C and an explosion at 190.2 ° C.

Example 7

Analogously to Example 1 or Example 6, using the addition of precipitated barium sulfate to the reaction mixture, a urea-formaldehyde condensate containing 3.2 wt. % water, 0.31 wt. 0.31 wt. % methylol and 1.2 wt. ash.

From this condensate (activated barium sulphate), technical 1,5-methano-3,7-dinitroso-1,3,5,7-tetraazacyclooctane (DNPT), and mixed triaryl phosphate as in Example 6, a mixture of the composition,% by weight, is prepared. .): 80% DNPT, 10% activated barium sulfate and 10% mixed triaryl phosphate. Using DTA as in Example 5, an onset of exothermic decomposition at 139.1 ° C and an explosion at 185.6 ° C are found.

Example 8

Analogously to Example 3, an activated zeolite containing 6.8 wt. water. 0.489 wt. % methylol and 70.69 wt. ash.

From this activated zeolite, technical 1,5-methano-3,7-dinitroso-1,3,5,7-tetraazacyclooctane (DNPT) and mixed triaryl phosphate as in Example 6, a free-flowing composition having the composition (wt.%) Is prepared: 65 % DNPT, 20% activated zeolite, and 15% wt. of mixed triaryl phosphate. Using DTA as in Example 5, an onset of exothermic decomposition at 138.6 ° C and an explosion at 181.9 ° C is found.

Claims (1)

OBJECT OF THE INVENTION Use of urea-formaldehyde condensates of surface-activated powdered water-insoluble inorganic substances, such as kaolin, zeolites, carbonates or sulphates of alkaline earth elements, characterized by a content of 1.2 to 92.3% by weight. ash as modifiers in the manufacture and / or application of blowing agents based on 1,5-methano-3,7-dinitroso-1,3,5,7-tetraazacyclooctane and / or azodicarboxamide.