CS230317B1 - Self-extinguishing composition for light current electrical engineering - Google Patents

Description

The invention relates to a flame retardant material suitable for low-current electrical engineering based on polyphenylene oxide in admixture with other polymers, with the addition of stabilizers, flame retardants, optionally pigments, lubricants and other additives.

Pure poles (2,6-dimethyl-1,4-phenylene oxide) are characterized by excellent electrical properties over a wide temperature and frequency range, very good dimensional stability, considerable heat resistance, flame retardancy and good mechanical strength, which together with excellent moisture resistance, acids, bases and alcohols predestines it for use in the electrical industry. However, its use in pure form is very limited due to the high melt viscosity. A common solution to this problem is to mix polyphenylene oxide with other polymers, most of which use clear or tough polystyrene in combination with fewer rubbers and polyolefins. These mixtures have very good flow and mechanical properties, but the addition of other polymers reduces thermoxidation stability and deteriorates electrical properties. In addition, a considerable amount of polystyrene in the compositions causes the material to be flammable, which means adding flame retardants in addition to the stabilizers for most applications, thereby further significantly deteriorating the electrical properties, in particular the loss factor.

Significant improvement of the electrical properties of stabilized polyphenylene oxide mixtures is achieved according to ČSN 201 766 by the addition of substituted guanidines or biguanidines as substances suppressing undesirable changes in polyphenylene oxide properties during the heat treatment. However, these mixtures are not self-extinguishing at a typical content of 50 wt% of the modifying polymers. ¹ has now been found that good flame retardancy of said compositions while maintaining excellent electrical properties of the material can be achieved by combining guanidine derivatives or biguanidine with elemental red phosphorus.

SUMMARY OF THE INVENTION The subject of the invention is a low-current polyphenylene oxide based flame retardant electrical material in admixture with styrene plastics and polyolefins, stabilizers and red phosphorus as a flame retardant, or other additives such as pigments or lubricants containing 0.05 to 3 parts by weight of guanidine derivatives. (lj

R ¹ R ³ \ /

N — C — N (I) / II \

R 2 NR ⁴ or biguanidine

R ⁴ R ⁴

R ² —NN — R ⁵ \ /

C - N - C (II)

Z I \

R ^{3 -} NR ⁷ N - R ^B wherein R ¹ to R ⁷ is hydrogen, methyl, ethyl, phenyl, tolyl or xylyl and 0.1 to 2 parts by weight of elemental red phosphorus.

By polyphenylene oxide is meant poly (2,6-dimethyl-1,4-phenylene oxide). The other component of the blend may be any of the following polymers, or combinations thereof, styrene plastic such as clear polystyrene, tough polystyrene or terpolymer of acrylonitrile, butadiene and styrene, polyolefins such as polyethylene, polypropylene, ethylene-propylene copolymer (thermoplastic or elastomeric) polyisobutylene, as well as ethylene - propylene - diene rubber or butyl rubber. The total content of these modifying polymers may range from 1 to 70% by weight, based on the mixture with the polyphenylene oxide. The material also contains thermo-oxidizing stabilizers, additives to improve resistance to atmospheric aging, possibly also pigments, lubricants, etc.

Flame retardant compositions of this type exhibit improved flame retardancy and substantially improved electrical properties (especially at higher temperatures) compared to materials prepared with the addition of other nitrogen bases and red phosphorus or a triaryl phosphate compound as a flame retardant. Compared to a material containing guanidine or biguanidine and a triaryl phosphate retarder, the above flame retardant compositions exhibit markedly better electrical properties and good flame retardancy.

The following examples illustrate the invention. The parts shown in the examples are by weight.

Example 1

To a mixture of 50 parts of poly (2,6-dimethyl-1,4-phenylene oxide), 43 parts of clear polystyrene, 7 parts of ethylene-propylene rubber, 2 parts of zinc oxide, 1 part of tris- [4- (1'-phenyl) jets Phosphoric acid 1-phenyl ester] stabilizer was added for A and B: 0.5 parts of N, N'-dimethylhexamethylenediamine, for C: 0.5 parts of dimethylguanidine All mixtures were retarded, for A: 5 parts of triphenylphosphate, in case of B and C: 2 parts of elemetary red phosphorus.

Polyphenylene oxide powder, whose viscosity number was 56.5 ml / g, measured in chloroform at a concentration of 0.3 g / 100 ml of solution at 25 ° C, was used to prepare these and other examples.

After thorough homogenization, the mixture was melted on a laboratory screw extruder and the extruded string was granulated. Plates were pressed from the granulate and test specimens were prepared from them by mechanical machining to determine the basic mechanical, electrical and thermal properties. The measured values of the compared materials are given in Table I.

Example 2

To a mixture of 50 parts of poly (2,6-dimethyl-1,4-phenylene oxide), 48 parts of tough polystyrene, 2 parts of polyethylene, 3 parts of titanium dioxide and a stabilizer consisting of: 1.2 parts of tris (nonylphenyl phosphite) and 0.2 parts of di-tert-butyl-4-methylphenol, 1.5 parts of phenyl-o-tolylxylylguanidine and flame retardants were added for A: 5 parts of isopropylphenyl diphenylphosphate, for B: 0.5 parts of elemental red phosphorus. The material was processed and evaluated as in the previous example, the measurement results are shown in Table II.

Claims (1)

5 Property 6 Table I Mixture C Temperature measurement [° C] Mixture A Mixture B loss factor, 50 Hz 23 25.10 ~ ⁴ 17.6.10- ⁴ 14 „5 .10 CSN 346 466 100 ALIGN! 112. 10 ~ ⁴ 48.2.10 “ ⁴ 27,6.10- ' 150 710. lir ¹ 215. 10 ⁴ 88,0.10- ' internal resistivity [cm] 23 2.2.10 ^ls 1.2.10 ¹⁶ 3.6. ΙΟ ⁴⁷ flammability, UL 94 [s] __ 23 19,2 11.3 classification V —1 V —1 V - 1 tensile strength [MPa] of micro body with a working section cross-section of 1 mm ² , 23 54.6 57.3 57.9 strain rate 50 mm / min notched toughness [J / cm ² ] CSN 640 612 23 0.59 0.55 0.57 Type 3 test specimen Vicat softening temperature [° C] ČSN 640 521, method B 139 147 149 Table II Property Measurement temperature Mixture A Mixture B PC] loss factor, 50 Hz 23 Íj4,. 10- ⁴ 9.8. ⁴ “ ⁴ 100 ALIGN! 58.ΙΟ “ ⁴ 19.0. ⁴ 150 285. ⁴ “ ⁴ 78.10-4 specific internal resistance [Ω cm] 23 3.0. 10-θ 3.8. ΙΟ ⁴⁷ flammability [s] -, 40 18 classification not compliant V - 1 tensile strength [MPaj 23 55.6 56.1 notch toughness [J / cm ² ] 23 0.80 0.71 Vicat softening temperature 141 150 ra SUBJECT OF THE INVENTION Flame retardant material for weak current or biguanidine (II) electrical engineering based on polyphenylene oxide mixed with styrene plastics and polyolefin R ¹ K ⁴ stabilizers and red phosphorus as 1 1 flame retardant, optionally other ingredients R ² —NN - -R5 dyes such as pigments or \ OF lubricants, characterized in that: contain 0.05 C-N-C up to 3 parts by weight of guanidine derivatives (11 Z 1 \ R ^{3 —} NR ⁷ N- -R ⁶ Rt R ³ \ OF wherein R 1 to R ⁷ is hydrogen, methyl, ethyl, phenyl, N — C — N (AND) lyl or xylyl; and 0.1 to 2 weight i / II \ elemental red phosphorus. R 2 NR ⁴ AND