SU526631A1 - Composition for producing foamed polyolefin - Google Patents

Description

The processes are gas-separated and shtpzaii iollmsra, which should proceed as possible synchronously. Using the mixture consisting of zinc oxide, zinc stearate and stearic acid, taken in the indicated ratio as an activator for the decomposition of azodicarbonamide, gives the maximum effect of reducing the decomposition temperature of azodicarbonamide, stabilizes the foaming rate of the polyethylene composition in a wide temperature range, contributes to the quality of the foam structure. In tab. 1 reduces the rate constant for the decomposition of azodicarbonamide depending on the zinc oxide content. Table 1 Change in the rate constant for the decomposition of azodicarbonamide depending on the concentration of zinc oxide (142 ° C) Zinc oxide concentration, weight. h. To 10 seconds on 1 weight. including azodicarbonamgda From table. 1 and the experimental data, the expediency of using zinc oxide in an amount of 0.08 wt. h. on 1 weight. hours of azodicarbonamide (respectively, 0.4 to 0.5 weight. hours on 5-8 weight. hours of azodicarbonamide). The drawing shows a graph of the rate of decomposition of azodicarbonamide in the presence of different amounts of zinc stearate. Curves 1 and 2 show, respectively, the kinetics of decomposition of azodic-1-carbonamide in the presence of 0.2 wt. h. and 0.4 wt. hours, and curves 3 and 4-0.6 weight. hours and 0.8 wt. including zinc stearate by 1 weight. including azodicarbonamide. From the data of the above dependence, it can be seen that the use of maximum amounts of zinc stearate is impractical, since the activation effect is sufficiently achieved when the amount of zinc stearate in an amount of 2 wt. hours {respectively 1.25-2.0 weight. hours 5-8 weight. h. azodicarbonamide). Curve 5 characterizes the gas release of azodicarbonamide in the presence of zinc stearate in an amount of 0.1 weight. h. on 1 weight. including azodicarbonamide. Maximum gas evolution was not achieved within 40 minutes. The activity of the catalytic system is also sensitive to the addition of stearic acid. In tab. Figure 2 shows the dependence of the foaming rate of the polyethylene composition on the content of stearic acid in the catalytic system. From tab. 2 that the rate of foaming of the polyethylene composition in the region is shown. Table 2 Dependence of the foaming rate of the composition, and on the content of stearic acid in the catalytic system. The rate of foaming of the composition, m / min The amount of stearic temperatures varies 153-162 ° C, or remains constant when the content of stearic acid is from 0.08 to 0.16 weight. h. on 1 weight. including azodicarbonamnda and increases in proportion to the temperature with 0.33 wt.% of stearic acid. h. on 1 weight. including azodicarbonamide. Therefore, the amount of stearic acid injected in the range of 0.08-0.16 weight should be considered the most optimal. h. on 1 weight. hours of azodicarbonamide (respectively, 0.4-0.6 parts by weight per 5-8 parts by weight of foaming agent). Thus, by using a catalytic system consisting of zinc oxide, zinc stearate and stearic acid, taken in a weight ratio of 1: 3: 1 -1: 3: 2, the maximum effect of reducing the decomposition temperature of azodicarboamide is achieved; however, its decomposition rate remains constant in the temperature range of 150-170 ° C, which contributes to a more homogeneous distribution and dissolution of the produced gas and coordination of the decomposition of azodicarbonamide and the polymer crosslinking process. The use of the aforementioned catalytic system allows the use of various methods for the processing of the polyolefin composition. The invention is illustrated by the following examples. Er and measures 1. I foam of 45 mm foam-filled blocks. A. Composition, wt. h .: Low-density polyethylene 100 (ip 2.0 g / 10 min) Azodicarbonamide6 Dicumyl oxide Irex 0.5 Zinc oxide 0.5 Zinc stearate 1.5 Stearic acid 1.0 The composition is prepared by displacing the components with polyethylene on a roller or in a Buss granulator temperature 110-1 5 ° C. Foaming is carried out in the form of 300X300X20 mm in size under a press pressure of 90-100 kg / cm at a temperature of 155-1.60 ° C for 40 minutes. The block foams on air after a quick release of pressure and has dimensions of 725 x 725 x 45 mm.

The foam has the following evoyetva. Seeming density, kg / m 55-60 Strength at tensile strength kgf / s 26,0 Relative elongation,% 190

Elasticity with rebound.

41

Water absorption in 24 hours, kg / m 0.04 Coefficacy Tenit Conductivity

kcal / mh-grad0.03

B. Composition, wt. h.: Low density polyethylene (IP 1.0 g / 10 min) 100 Azodicarbonamide 8 Dicumyl peroxide 1.0 Zinc oxide 0.6 Cinnamon stearate 2.0 Stearic acid 1.3 The method of preparation of the composition is the same as in paragraph A.

The composition in the form of granules or roll sheets is loaded into a mold and under a press pressure of 90-100 kg / cm at a temperature of 150-155 ° C for 40 minutes. The pressure is then quickly removed and the preform foams when the mold is opened. A foamed block is formed with a finely cellular, uniform structure and the following properties.

Seeming with density

Strength at stretching, kgf / cm 4,5 Relative elongation,,% 140 Elasticity by rebound,% 45 V. Composition, weight. h .: Low density polyethylene

(IP 1.0 g / 10 min) 80

Ethylene vinyl acetate copolymer20

Azodicarbonamide 6,0

Dicumyl peroxide1,0

Zinc Oxide 0.5

Zinc Stearate1,5

Stearic acid 0.8

The composition is prepared by shifting the components on the rollers at a temperature of 105-110 ° C. The rolled billets are placed in a mold that does not allow expansion of the material, 300X300X20 mm in size and press iodine with a pressure of 90-100 kg / cm at 160 ° C for 20 minutes. Then the temperature is reduced to 140-145 ° C and the pressing is continued for another 20 minutes. After this time, the pressure is released and the pressed billet is foamed in air to form a block of size 725x725x x45 mm. The resulting foam has the following properties.

Seemingly with ilotyp,

Tensile strength when grown as kgf / cm 5,0

Relative elongation,% 140

Strength by rebound,.% 44

Water absorption in 24 hours, kg / m 0.08

6

Heat conductivity coefficient, kcal / m-hr. 0.041 and p. 2. Meter 2. Preparation of 16 mm diameter peiopolyethylene profiles by extrusion of subfoil bundles and subsequent foaming by secondary heating.

Composition KOMP31CHII, weight. h .: Low-density polypatiles

(p 0.6-1.0 g / 10 mpn)

100 5

Azodicarbonamide

0.5 Dicumyl peroxide

0.4 Zinc Oxide Zinc Stearate

1.25

0.5

Stearic acid

This polyethylene composition is prepared in a Buss. The polyethylene granules with the introduced components are loaded into the extruder funnel. The composition is extruded in the form of a round rod with a diameter of 8 mm. The temperature in the zones of the cylinder increases from 100 to 120 ° C. The foam is harvested in a salt or silicone bath at a temperature of 210-220 ° C for 3-4 minutes.

The properties of the foam tow are as follows. Seeming with density

Strength at stretching, kgf / cm 3.65 Relative elongation,% 195 Compression stress, kgf / cm When deformed by 10% 0.8 When deformed by 20% 0.9 Water absorption,% less than 0.3

Example 3. Obtaining pepoiolitep in closed form under the pressure of inert gases and vapors.

Composition, wt. h .: Low density polyethylene

(ip 0.6 g / 10 min) 100

Azodicarbonamide 6,0

Dicumyl peroxide1,0

Zinc Oxide 0.5

Zinc Stearate1,5

Stearic acid1,0

Granules of polyethylene with the added additives, mixed in the Buss granulator, are filled in the amount of 50 g into a 340 cm form.

The form is placed in an autoclave, which is heated to a temperature of 190 ° C and maintained at this temperature for 50 minutes with a pressure of at least 5 MPa in an inert gas. After the specified time has elapsed, the pressure is cleared and all feeds in the form take place.

Next, the mold is cooled to a comedian temperature and the finished product is removed with a smooth surface and a foamed core.

Claims (1)

Apparent to product density, Water absorption for 24 hours, kg / m absent Water absorption at 2.5-3.0 these for 30 MI1G, kg / m20.07 Claim of the invention Composition for the preparation of foamed polyolefin containing polyolefin, azodicarbonamide, dicumyl peroxide and foaming agent decomposition activator, characterized in that, in order to make it possible to regulate the process of transformation, a mixture of zinc oxide, zinc stearate and stearic acid, taken in weights, is used as an activating agent for decomposition of the foaming agent. sootnosche m and n, respectively, from 1: 3: 1 to 1.5: 5: 3, the components by weight. including the following ratio Polyolefin 100 Azodicarbonamnd 5-8 Dicumyl peroxide 0.5-1.0 Activator of the decomposition of the active agent 2.05-3.9 iff2030 Min duration 0