CS240977B2 - Foamable particle from styrene polymere and method of its production - Google Patents

Description

The invention relates to foamable particles of styrene polymer, such as foamable polystyrene particles. In particular, the invention relates to such foamable particles which are more suitable in the manufacture of foamed articles because they have a reduced flammability.

The light-transmissive styrene polymer particles and articles made from these styrene particles are well known. Examples of such articles include insulated building panels, shop items, decorations, padding, floats and the like, hot and cold bunkers, portable refrigerators and the like. their low weight and good thermal insulation properties.

the polymeric particles are usually prepared by imparting the particles to a suitable blowing agent such as pentane. In the manufacture of foamed articles, the impregnated foamed particles or beads are first subjected to a pre-foaming process wherein the beads are heated by a steam heater in an open space to produce pre-foamed particles of relatively low density.

The foamed pearls complete the swelling.

The mold is then cooled to the desired closed mold and the steam is supplied again. Finally, the mold is cooled and the shaped article is removed therefrom.

A prerequisite for the use of foamed foam products in various applications is that they have a reduced flammability. This is used in the state of the art.

in particular in the case of foamed products, as in the prior art there is room for possible improvements to reduce the flammability of foamed products.

however, there is still a high synergistic activity in this field, and there has also been found, in accordance with the invention, a combination of substances exhibiting flame retardant performance. Under the term synergistic, it is understood that the reduction in the heat that is absorbed in the following formulation is greater than the reduction in the heat that would theoretically be expected based on the sum of the effects of the two ingredients.

and 0.5 to 2.5% fanotics are based on weight

It is an object of the present invention to provide a foamable particulate of a styrene polymer, e.g. a physical blowing agent, for example pentane, characterized in that it contains 0.1 to 0.5% of titanium (allyl ether) / tetrahydroisoisphalate A nibrooethyl-4-cyclocyclthexane, all percentages of styrene polymer.

The additives may be introduced into the particle by external mixing of the particles containing the blowing agent with the additives, but preferably the additives are introduced into the particle together with the blowing agent.

The invention therefore also relates to a process for the production of a foamable particle from a styrene polymer, for example polystyrene, in which the particles are subjected to a physical blowing agent, for example pentane, characterized in that the blowing agent is present in 0.1 to 0.5% by weight. and 0.5 to 2.5% of dibromo-dibromo-dibromocyclohexane, all percentages based on the weight of the styrene polymer.

Examples

To a kettle equipped with a stirrer was charged with 100 parts of H [noOnnstních water-, hmo0nottní 2 parts of tricalcium phosphate, 0.05 parts hmotnottního natriím dodnc ^y lienzensuiftnáts, 100 parts оо ^ ^ п п ^! ^ Macic polystyrene beads about 1 mm diameter and 8 % by weight of n-pentane. In the examples of the invention, additives to reduce flammability in the amounts set forth below are also added in the present invention.

The contents of the boiler are heated to a temperature of 102 to 110 ° C and maintained at this value for 7 to 10 hours with stirring. Then the boiler is cooled to room temperature, its contents are acidified with nitric acid, the beads are separated from the aqueous medium, washed with water and air-dried at room temperature.

For the pre-foaming, the beads are placed in a boiler equipped with a stirrer and a steam inlet of 2 mm bead, the foaming is carried out by introducing steam between the beads for about 2 minutes. The vapor pressure is 34 kPa. The foamed particles have a diameter of about 5 mm.

To test the properties of the resulting molded foam article, test molds of 15 x 30 x 15 cm were used. The mold is provided with a jacket allowing the injection of steam into its contents.

The mold was partially filled prepuffs and · then into it for about 10 to 20 seconds ^Fr indicates a ra te ^ rt ¹ 10 ⁴ ° C. Shaped annual ^b e ^{k p} and ^{NEC hook} zc ladnout ^h and ^{Z h} may adopt ^y s from the mold.

Samples of molded foamed articles are prepared by the above process, both without and with the addition of flame retardants according to the invention. · Comparative annoyance results are presented below. ♦

The properties of the resulting foam shaped articles upon burning are measured on test strips measuring 23 x 10 x 1.3. cm, which are cut from the molded object with heated wire.

The test strip is suspended vertically, with its non-longest dimension in the vertical position. A gas burner about 1.3 cm long is swept at the sample at a distance of about 2.5 cm above its base.

The flame is directed to the test sample until it floats, and then is flamed. Both the vertical and horizontal dimensions / height and width / areas are changed. Combustion and a combination of the two measured data is used to characterize the flammability stage of Table 1, wherein stage one represents an excellent result and stage 4 means that the sample failed.

Table 1

Degree of flammability

Vertical dimension of combustion area

Hooiz. dimension of combustion area

1 0 to 10 cm 3 to 4 cm 2 more than 10 to 16 cm more than 6 to 8 cm 3 more than 16 to 20 cm more than 6 to 8 cm 4 more than 20 cm more than 8 cm

Pouuitý bis / allsllthlt / tetrabtsm> isfenslu A is an off-white crystalline solid of mooekulov hmoonooti 623 ^{s, 9 H} contained in bromine ⁵ 1 ² ^ tonmtanotní% and having ^a melting ^point LL ⁰ and ^f l ²⁰ ° C. Pouuitý dibromethyldibromcsklohexan is a white crystalline powder mmlekulové weight of 428, bromine content 74% ϊnoSnnstníc ^h and ^h ^ Ы Шр the 6 ^th and ^{5 to 80} ° C.

Table 2 shows the results of the flame retardant moldings of expanded polystyrene foam containing additives for delivery of the present invention in comparison with molded expanded polystyrene products which did not contain no ingredients. In all cases, the additive content is based on the polystyrene moisture content.

Table 2

Example Additive None

0.2% bis / allyl ether / tetrabromobisphenol A

1.0% dibromethyldibromocyclohexane

0.2% bis (allyl ether) tetrabromobisphenol A and

1.0% dibromethyldibromocyclohexane

Degree of flammability

1,5 to 2

0.5% bis / allyl ether / tetrabromobisphenol A a

0.6% dibromethyldibromocyclohexane

By comparing the results obtained in Examples 2 and 3 with those obtained in Examples 2 and 5, the synergistic effect of the flame retardants used according to the invention is obvious beyond any doubt.

The improved flame retardant styrene polymer particles mentioned above are obtained by introducing only small amounts of bis / allyl ether / tetrabromobisphenol A and dibromethyldibromocyclohexane into the styrene polymer particles.

Particularly useful are foamable styrene polymer particles containing from about 0.1 to about 0.5% bis (allyl ether) tetrabromobisphenol A and from about 0.5 to about 2.5% dibromethyldibromocyclohexane, both based on the weight of the styrene polymer.

In a preferred embodiment of the invention, the additives are introduced into the styrene polymer particles during the introduction of the blowing agent. However, advantageous results are also obtained when the additives are guided by external mixing into the foamable styrene polymer particles into which the blowing agent has previously been introduced. The mixing can be carried out by rolling the dried foamable styrene polymer particles with the desired amount of additives.

The invention has been described in detail by way of example of foamable polystyrene particles containing small amounts of additives according to the invention. However, the invention is not limited to polystyrene since other vinylaromatic polymers may be used.

These polymers include vinylaromatic polymers derived from monomers such as vinyltoluene, isopropylstyrene, alpha-methylstyrene, chlorostyrene, tert-butylstyrene and copolymers of vinylaromatic monomers and butadiene, alkyl acrylates, acrylonitrile and the like. means the particles of all these polymers and copolymers.

In the practical examples illustrating the invention, pentane blowing agents were used. The invention is not limited to the use of pentane as it is. other blowing agents can also be used.

Suitable blowing agents are butane, isopentane, cyclopentane, hexane, heptane, cyclohexane and lower boiling halogenated hydrocarbons. Mixtures of the above blowing agents may also be used. The foamable styrene polymer particles typically contain from about 1 to about 20% by weight of the blowing agent.

The blowing agent swelling to obtain foamable styrene polymer particles can be carried out over a wide temperature range, namely at a temperature in the range of about 60 to about 150 ° C.

Claims (2)

SUBJECT OF THE INVENTION A foamable particle of a styrene polymer, for example polystyrene, comprising a physical blowing agent, for example pentane, characterized in that it contains 0.1 to 0.5% by weight of bis / allyl ether / tetrabromobisphenol A and 0.5 to 2.5% by weight. dibromethyldibromocyclohexane, all percentages based on the weight of the styrene polymer. 2. A process for producing a foamable styrene polymer particle such as polystyrene according to item 1, wherein the styrene polymer particle is impregnated with a physical blowing agent such as pentane, wherein the impregnation is carried out in the presence of 0.1 to 0.5% by weight. % of bis (allyl ether) tetrabromobisphenol A and 0.5 to 2.5% by weight of dibromethyldibromocyclohexane, all percentages being by weight of the styrene polymer.