GB2082592A

GB2082592A - Fire protection components containing brominated diphenyl ethers

Info

Publication number: GB2082592A
Application number: GB8119487A
Authority: GB
Original assignee: Chemische Fabrik Kalk GmbH
Current assignee: Chemische Fabrik Kalk GmbH
Priority date: 1980-06-24
Filing date: 1981-06-24
Publication date: 1982-03-10
Also published as: GB2082592B; DE3023492A1; DE3023492C2; JPS5790077A; FR2485559A1

Abstract

A fire protection component for cresol- and phenol-based resin-bound pressed laminates, which comprises about 50. % of a mixture of bromine- containing diphenyl ether which contains: 55 - 70 wt. % hexabromodiphenylether, 12 -18 wt. % heptabromodiphenylether, 8 - 18 wt.% octabromodiphenylether and 8 -16 wt. % lower bromination derivatives of diphenylether, about 16 wt. % tetrabromo-2,2-bis (4-hydroxyphenyl)- propane, about 34 wt. % alkylarylphosphate.

Description

SPECIFICATION Fire protection components, their preparation and their use This invention relates to fire protection components, their preparation and their use.

Pressed laminates have been proposed which have been made by compressing at elevated temperatures of about 160 C, glass or textile webs which are impregnated with cresol-resol resins or contain paper strips saturated with phenol-resol resins. In order to make such pressed laminates the glass or textile webs or paper strips which serve as reinforcement material are impregnanted with the resin solution by coating, spraying or dipping whereby the resin already experiences a pre-condensation. The thus-treated strips are divided up into portions of similar dimensions and an appropriate number of them are layed on top of each other and are treated in a press for 30 - 90 minutes under a pressure of 80 - 180 kp/cm2 and a temperature of 140 - 1 80 C, until the curing of the resin is completed.

These pressed laminates can also be covered with a copper foil and in this form used for the production of printed circuits for electrical apparatus. In order to reduce the risk of fire in apparatus provided wth such circuits, for example through short circuits or sparks, it has become necessary to an increasing extent to make the pressed laminates of such printed circuits fire resistant.

To this end, it has been proposed to add to the resin solutions, before the impregnation step, pentabromodiphenylether in combination with organic phosphorus compounds such as diphenylcresylphosphate as fire protection components. In order to fulfil the fire protection standard VO defined in "Tests for flammability of plastic materials", 2nd edition, (1975) published under the designation UL 94 by "Underwriters Laboratories Inc." about 30 weight % of this fire protection material, based on the cured resin, must be added to the resin solution. However, the mechanical properties of such pressed laminates, in particular their bending strength, are reduced drastically and to an unwanted extent by this addition.

Ways were therefore sought of providing fire protection components with similar or better fire protection properties which have little or no influence on the mechanical properties of the pressed laminates.

According to the invention there is provided a fire protection component for cresol- and phenol-resol resin-bound pressed laminates, which comprises about 50 wt. % of a mixture of bromine-containing diphenyl ethers which contains: 55 - 70 wt. % hexabromodiphenylether 12 - 18 wt. % heptabromodiphenylether 8 - 18 wt. % octabromodiphenylether and 8 - 16 wt. % lower bromination derivatives of diphenylether about 16 wt. %tetrabomo-2,2-bis(4-hydroxyphenyl)-propane about 34wt % alkylarylphosphate.

The tetrabromo-2,2-bis(4-hydroxyphenyl)-propane is preferably prepared by a conventional method. The alkyl aryl phosphates, particularly diphenylhexylphosphate, used in the invention are known compounds.

To make the pressed laminates which are made difficult to burn by the incorporation of the fire protection components of the invention, the cresol-resol resin or the phenyl-resol resin are dissolved in oganic solvents such as methanol, toluene, acetone or a mixture of such solvents, in amounts which are conventional for pressed laminates. The solvents can also contain water.

In order to make the fire protection components according to the invention, diphenylether dissolved in 141 ,2,2-tetrachloroethane or onmethylenebromide is first brominated at a temperature of 10 - 30 C in an amount of 6 to 7 moles bromine per mole diphenylether. As small amounts of hydrogen bromide generated by the bromination remain in the reaction mixture the reaction mixture is scrubbed with a corresponding mount of an alkaline-acting substance such as sodium carbonate, sodium hydrogen carbonate, calcium hydroxide or calcium chloride oxide in aqueous solution or suspension, in order to remove the hydrogen bromide.After separating the aqueous phase from the residual solution of the bromine derivatives of the diphenylether the tetrabromo-2,2-bis(4-hydroxyphenyl)-propane and the alkylarylphosphate are homogeneously dispersed in this solution and the solvent distilled off from the mixture. The fire protection components according to the invention remain as a clear flowable melt.

The fire protection components are then introduced in an amount of 20 - 30 wt. % into the resin solution and dissolved. If necessary the fire protection components can be preliminatydissolved in a part of the solvent or solvent mixture used for the resin solution and this solution can then be stirred into the resin solution.There is thus formed a resin solution containing fire protection material with which the paper strips or glass fibre or textile web can be impregnated using conventional methods and dried at a temperature of 100"C. These impregnated and dried strips are then divided into portions of the same size which corresponding to the desired thickness of the pressed laminate are stacked one on top of the other and which are treated in a press, particularly a multi-daylight press, at a temperature of 160 -170 C for 30 - 90 minutes under a pressure of 80 to 180 kp/cm2.

After opening the press the moulding is removed and cooled to room temperature. The fire protected pressed laminate prepared in this way has mechanical and electrical properties which are only immaterially altered with respect to a similar pressed laminate which is not fire protected.

Example 1 (Preparation of fire protection components) 340 parts by weight diphenylether is dissolved in a 1000 parts by weight 1,1,2,2-tetrachloroethane and 2080 parts by weight bromine stirred into this solution at a temperature of 15 - 2000. After a reaction time of 120 minutes at the same temperature 500 parts by weight of a 5% sodium carbonate aqueous solution is stirred into the reaction mixture. The mixture is allowed to stand and the aqueous phase which separates out is mechanically removed from the organic phase into which 432 parts by weight tetrabromo-2,2-bis(4hydroxyphenyl)-propane and 918 parts by weight hexyldiphenylphosphate are stirred. The solvent is dissolved off from this mixture and a clear flowable melt with a bromine content of 47 wt. % and a phosphorus content of 3.2 wt. % remains as product.This melt contains 50 wt. % of a mixture of 66.2 wt. % hexabromodiphenylether 13.8 wt. % heptabromodiphenylether, 10.0 wt. % octabromodiphenylether, 10.0 wt. % lower bromine derivatives of diphenyl ether 16 wt. % tetrabromo-2,2-bis(4-hydroxyphenyl)-propane, 34wt. % hexyldiphenylphosphate.

Example 2 (Preparation of impregnation solution and the pressed laminates and comparative tests).

Experiment 1 (comparison) describes products which are not fire protected.

Experiment 2 (comparison) describes products fire protected with pentabromodiphenylether and diphenylcresylphosphate Experiment 3 (invention) describes products containing fire protection components according to Example 1.

Amounts are in parts by weight.

Experiment No.

1 2 3 Impregnation solution 50%solutionofa 100 100 100 cresol-resol resin in a mixture of 50 wt. % acetone and 50 wt. % isopropanol pentabromodiphenylether 25 diphenylcresylphosphate 10 fire protection components 26 according to the invention Pressed laminate 1 2 3 cotton paper 50 50 50 cresol-resol resin 50 50 50 pentabromodiphenylether 25 diphenylcresylphosphate 10 fire protection components 26 of the invention Wt. % fire protection 0 26 20.5 material based on the laminate Fire behavior according to UL 94 material burns without + extinguishing itself and forms burning drops V-O (self extinguishing within 5 seconds; material does not form burning drops) self extinguishing after 7 sec 2 sec Physical properties Breakdown voltage at a thickness of 1.5 mm according to DIN 53481 35 kV 34 kV 35 kV Bending strength according to DIN 53452 81 N/mm2 79N/mm2 80N/mm2 Oxygen index LOI 19 29 30.5

Claims

1. A fire protection component for cresol- and phenol-resol resin-bound pressed laminates, which comprises about 50 wt. % of a mixture of bromine-containing diphenyl ethers which contains: 55 - 70 wt. % hexabromodiphenylether 12 - 18 wt. % heptabromodiphenylether 8 - 18 wt. % octabromodiphenylether and 8 - 16 wt. % lower bromination derivatives if diephenylether about 16 wt. % tetrabomo-2,2-bis(4-hydroxyphenyl )-propane about 34 wt. % alkylarylphosphate.

2. Method of making the fire protection component according to claim 1 wherein diphenylether dissolved in 1 ,1,2,2-tetrachlorethane or methylenebromide is brominated at a temperature of 10 - 300C with 6 to 7 moles of bromine per mole of diphenylether, the resulting reaction mixture is scrubbed with an alkaline reacting substance selected from sodium carbonate, sodium hydrogen carbonate, calcium hydroxide and calcium chloride oxide in aqueous solution or suspension and the aqueous phase removed, and the tetrabromo-2,2-bis (4-hydroxyphenyl)-propane and the alkylarylphosphate are uniformly distributed in the remaining solution of the brominated derivative and the solvent is distilled off from the mixture.

3. Use of the fire protection component according to claim 1 in which the fire protection component is mixed with the resin solution in an amount of 20 - 30 wt. % before the resin solution is used to impregnate the reinforcement material.

4. A cresol- or phenol-resol resin bonded pressed laminate which contains a fire protection component according to claim 1.

5. A fire protection component substantially as hereinbefore described in Example 1.