RU2489458C1 - Polyvinyl chloride-based composition for insulation and sheaths of wires and cables - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: composition for insulation and sheaths of wires and cables contains polyvinyl chloride, a plasticiser, a heat stabiliser and pyrogenic silicon dioxide with particle size of 5-40 nm and specific surface area of 175-380 m²/g.

EFFECT: low viscosity of the molten composition, high frost-resistance, thermal stability and physical and mechanical properties.

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Description

The invention relates to the field of plastics processing, in particular, to polymeric compositions based on polyvinyl chloride (PVC), which are used for the manufacture of insulation and shells of wires and cables.

The task was to develop a plasticized composition based on PVC for insulation and shells of wires and cables, which has improved processability and high physical and mechanical properties.

The processability improvement ™ was evaluated by a decrease in melt viscosity and was characterized by a relative viscosity, which was calculated as the ratio of the viscosity of the filled composition to the unfilled.

The prototype of the invention is a polyvinyl chloride composition used in the cable industry, containing PVC, plasticizer, stabilizer and filler - white soot with a specific surface area of 20-40 m ² / g in an amount of 2-15 wt.h. per 100 parts by weight PVC (USSR Author's Certificate No. 469827, C08F 29/18, publ. 30.04.75). Introduction to the composition of PVC composition of soot with a specific surface area of 20-40 m ² / g in an amount of 2-15 wt.h reduces the melt viscosity of the composition while maintaining good physical and mechanical properties. Frost plastic contained in the author's certificate of -55 - -60 ° C, a melt viscosity at 170 ° C - 1.25 × 10 ³ - 6.3 × 10 ² pz. Reproduction of the specified composition and testing it according to the methods available to the authors showed that with the introduction of white soot with a specific surface area of 20-40 m ² / g in an amount of 2-15 wt.h. the relative viscosity of the composition is 0.74-0.87, and frost resistance decreases from minus 65 ° C to minus 45 - minus 60 ° C. White soot, used according to the copyright certificate and having a specific surface area of 20-40 m ² / g, is precipitated silica of the formula mSiO ₂ · nH ₂ O with an average particle size of 120 nm.

The aim of the invention is to reduce the melt viscosity of a plasticized composition based on PVC, increase its frost resistance, thermal stability and physical and mechanical properties.

To achieve this goal, a composition based on PVC for insulation and shells of wires and cables, including plasticizer, heat stabilizer and silicon dioxide, contains pyrogenic silicon dioxide with a particle size of 5-40 nm and a specific surface area of 175-380 m ² / g as the latter. in the following ratio of components of the composition, parts by weight:

PVC one hundred Plasticizer 40-80 Thermal stabilizer 3-15 Pyrogenic Silica with a particle size of 5-40 nm and specific surface area 175-380 m ² / g 0.05-0.8

As fumed silica, you can use Orisil A-175 (10-40 nm), Orisil A-300 (5-20 nm), Orisil A-380 (5-15 nm), manufactured by Orisil LLC (Ukraine) according to GOST 14922-77 Aerosil, as well as Aerosil A-175, Aerosil A-300, and Aerosil A-380 from Evonik Degussa Gmbh and others. You can also use fumed silica, on the surface of which diethylene glycol (ADEG, 16 nm) is grafted, ethylene glycol (AEG, 16 nm), etc.

As a plasticizer, you can use dioctyl sebacinate (DOS), dioctyl phthalate (DOP), trioctyltrimellate (TOTM), or mixtures thereof, etc.

As a thermal stabilizer, tribasic lead sulfate (TOSS), dibasic lead phthalate (DOPTS), dibasic lead stearate (DOSS), etc. can be used.

The composition may additionally contain targeted additives, such as antioxidants, lubricants, stabilizers, flame retardants, pigments, etc.

For comparative tests on the prototype used white soot according to GOST 18307-78 brand BS-30 with a particle size of 60-108 nm and a specific surface area of 35 ± 10 m ² / g

The following are examples illustrating the invention.

Example No. 1

In a heated mixer of Henshel company with a volume of 10 l at a temperature of 40 ° C load 100 wt.h PVC, 5 wt.h. TOC temperature stabilizer, 0.05 parts by weight Orisil A-175 fumed silica with a particle size of 10-40 nm and a specific surface area of 175 m ² / g, stirred to a temperature of 60 ° C for 15 minutes Then, 50 parts by weight are added to the mixer. plasticizer DOS and continue mixing the mixture to a temperature of 100 ° C for 15 minutes. Then the mixture was cooled to room temperature. The powder mixture is rolled on oil-heated rollers at a temperature of 160 ° C for 5 minutes. The resulting rolling is pressed at a temperature of 165 ° C for 10 minutes

The obtained samples determine the frost resistance of plastic compounds in accordance with GOST 5960-72 on three samples with a size of 130 × 10 mm and a thickness of (1 ± 0.1) mm. The brittle temperature is taken to be the minimum temperature at which all samples maintained their integrity during bending by 180 °.

Tensile strength and elongation at break were determined according to GOST 11262-80 at a temperature of (20 ± 2) ° С.

The melt viscosity of the plastic compounds was determined using an Instron model 3211 capillary rheometer with a capillary diameter of 0.127 cm and a length of 2.55 cm at 165 ° C and a shear rate of 3.79 s ^-1 .

The relative viscosity (η _rel ) is calculated as the ratio of the viscosity of the filled composition (η _n ) to unfilled (η _about ):

$${\eta }_{\mathrm{about}tn}=\frac{{\eta }_n}{{\eta }_{\mathrm{about}}}$$

The thermal stability of the compositions was determined by the method of "Congo-mouth" according to GOST 14041-91 at 200 ° C.

The properties of plastic compounds are given in the table.

Examples No. 2-17 (according to the invention)

The method of obtaining the composition and testing methods of plastic compounds in example 1. The composition and properties of the compositions are shown in the table.

Example No. 18 (based on the prototype - USSR copyright certificate No. 469827)

Example No. 19 (prototype)

A method of obtaining a composition and testing methods of plastic compounds in example 1. The composition and properties of the compositions are shown in the table

Examples No. 20-27 (for comparison)

The method of obtaining the composition and testing methods of plastic compounds in example 1. The composition and properties of the compositions are shown in the table.

From the data given in the table it follows that the introduction into the composition of the claimed plasticized PVC composition of fumed silica with a particle size of 5-40 nm and a specific surface area of 175-380 m ² / g in an amount of 0.05-0.8 wt.h. per 100 parts by weight PVC can significantly reduce the melt viscosity of the composition (the relative melt viscosity is 0.52-0.70), increase frost resistance to minus 50 ° С - minus 70 ° С, thermal stability up to 230-245 min., Tensile strength up to 18.9- 21.0 MPa, elongation at break up to 365-405%. These indicators are significantly higher than the parameters of the prototype described in the description of the USSR author's certificate No. 469827, and obtained by reproducing this invention using 2-15 parts by weight of soot with a particle size of 60-108 nm and a specific surface area of 35 ± 10 m ² / g (grade BS-30 according to GOST 18307-78). The relative viscosity of the melt according to the prototype is 0.71-0.87, frost resistance minus 45 ° C - minus 60 ° C, thermal stability 180-207 min, tensile strength 17.0-19.7 MPa, elongation at break 315-370 % (see examples No. 1-17 in comparison with No. 18-19).

The use of fumed silica with a particle size of 5-40 nm and a specific surface area of 175-380 nm in quantities outside the claimed does not reduce the viscosity of the melt (see examples No. 20 and 21).

Pyrogenic silicon dioxide as a filler for PVC is known. It is also known that the introduction of Aerosil thickens PVC compositions, gives them thixotropic properties (Fillers for Polymer Composite Materials, edited by G. Kats, Moscow, Chemistry, 1981, pp. 177-179). A decrease in the melt viscosity with the introduction of a very small amount (0.05-0.8 parts by weight) of fumed silica with a particle size of 5-40 nm and a specific surface area of 175-380 m ² / g was an unexpected effect that falls outside the well-known pattern of increasing the melt viscosity of the plasticized PVC composition with the introduction of fumed silica.

The increase in melt viscosity with the introduction of fumed silica in the composition of the PVC composition in amounts of 2-15 wt.h. confirmed by examples No. 22-24.

Examples No. 25-27 show that white carbon in the claimed amounts of fumed silica 0.05-0.8 wt.h. does not reduce the viscosity of the melt.

Claims (1)

Composition based on polyvinyl chloride for insulation and shells of wires and cables, including plasticizer, heat stabilizer and silicon dioxide, characterized in that it contains fumed silica with a particle size of 5-40 nm and a specific surface area of 175-380 m ² / g as silicon dioxide in the following ratio of components of the composition, parts by weight:
polyvinyl chloride one hundred plasticizer 40-80 thermostabilizer 3-15 fumed silica with a particle size of 5-40 nm and specific surface area 175-380 m ² / g 0.05-0.08