The present invention relates to a modifier for expandable and expanded materials, especially polystyrene, which improves the resistance of the final material, and in particular its thermal resistance, resistance to ultraviolet radiation and ozone and other weather conditions.

Expanded polystyrene (EPS) is a polymer material which is most frequently used in thermal insulation, e.g. in the construction industry. It is characterized, inter alia, by a very low thermal conductivity index and low density. In order to enhance the resistance of EPS to the operation of ultraviolet rays and heat streams of high temperature, organic and mineral flame retardants and their compositions are used as well as factors and compounds released as a result of thermal decomposition of the components.

Styrene polymers, and expanded styrene polymers in particular, demonstrate very low resistance to heat streams of more than 85°C in which such polymers undergo physical, chemical and geometrical degradation; this - through passage into the liquid phase and loss of thermal insulation properties - may lead to the initiation of burning and also leads to their destruction.

A number of methods and preparations are known which reduce the flammability and enhance the thermal resistance of EPS with respect to its surface and weight but their effectiveness is insufficient. Additionally, in high temperature, well known and commonly applied preparations which reduce flammability and thermal resistance undergo pyrolysis thus leading to pyrolysis of EPS; as a result, compounds are released which may additionally cause for instance corrosion of metals being also catalysers of combustion processes and toxic agents.

Well known and commonly applied solutions concerning the preparation of polystyrene-based materials, which enhance their resistance to high temperature are involved with an application - as flame retardants - of compounds or compositions of compounds containing halides (e.g. HBCDD - hexabromocyclododecane). The above compounds or their simple compositions operate only in a temperature increased by their pyrolytic decomposition which results in the destruction, degradation or cracking of polystyrene the effect of which is its reduced flammability.

Polish patent application P.390189 presents prepared styrene polymers, especially polymers intended for expansion and production of thermal insulation partitions, with the required non-flammability, mechanical, geometrical and insulation characteristics, containing styrene polymer, organic porophores, and, optionally, surface-active agents or, optionally, technological additions such as plastifiers characterised in that they also contain an organic and/or inorganic neutralizing preparation in solid or liquid form, preferably with an addition of ascorbic acid and, optionally, they contain an addition in the form of organic auxiliary preparations in solid or liquid form, preferably with an addition of ascorbic acid. The neutralising preparation consists of ammonium bromide and/or guanidine phosphate, monoammonium salt of sulphonic acid and, optionally, ascorbic acid and the auxiliary preparation is an acrylate/fluoroalkyl copolymer which contains dipropylene glycol ethyl ether.

Another example of a solution of this type is Polish patent application P.380124, which provides knowledge on the method of neutralizing preparation of expandable and expanded materials, especially polystyrene, which improves the resistance of the final material (inter alia thermal resistance, resistance to ultraviolet radiation, ozone), which consists in preparing a water suspension activated with carbonic acid diamide with an addition of surface-active agents and/or a nitrogen compound solution, and thereafter, the said solution or suspension is used to prepare the material through its application, in the presence of steam and compressed air, directly onto the granulate to be expanded and/or after preliminary expansion of the granulate. The subject of the invention is also expandable and expanded materials, especially polymer, so prepared, which are used, inter alia for thermal insulation of thermal partitions, vibroacoustic compartments, etc., used mainly in the construction industry. Canadian patent application CA2051774 presents an example of such a concept whereby a water solution which retards burning is applied, inter alia, for flame retardancy of polyolefin, and which contains: water soluble ammonium salt (ammonium phosphate or ammonium bromide), organic phosphates and stable binder for resins.

A similar concept is adopted in Canadian application CA2019325 which describes a composition enhancing flame retardancy of various materials (paper, cotton, wood, polymer materials). The preferred composition of the material described in the aforementioned invention is ammonium bromide, boric acid, alcohol, a surface-active agent and water. Auxiliary additions are chosen from amongst: sodium phosphate, monoammonium phosphate, diammonnium phosphate, organic phosphate, phosphorus oxide, wood ash or metallic sodium.

Considering the toxicity of the products of decomposition resulting from pyrolisis and thermal transformations of some of modifiers applied to date, e.g. as preparations reducing the flammability of polymer materials, it become necessary to study the application of compounds whose decomposition products would be friendly to natural environment and humans and which, at the same time, would meet the expectations of the production and modification of polystyrene.

In expandable and expanded materials applied, e.g. in the construction industry, exposition to long-term ultraviolet radiation and ozone of atmospheric origin, results in the destruction basic bonds in the materials, their depolymerisation leading to considerable changes in their resistance parameters and change in the colour and smoothness of their surface, which has an additional negative consequences in the form of an extension of their specific surface, an increase in the generation of electrostatic charges which cause nuclei of radicals of endogenic fires leading to exogenic fires in objects. The subject of examination was therefore a modifier for expandable and expanded materials, especially polystyrene, which would improve considerably the material's resistance to heat streams and which would, at the same time, have a positive effect on the mechanical properties of the modified material. During laboratory tests on the composition and application of the modifier for expandable and expanded materials the flammability of the materials, the lambda coefficient, the change in their electrical conductivity and pH have been examined.

The aim of the invention is to provide a modifier for expandable and expanded materials, especially polystyrene, improving the resistance of the final material to heat streams and eliminating the negative impact of ultraviolet radiation and ozone on the surface of the materials (used mainly in the construction industry and exposed to all sorts of weather conditions) through buffer transformation of energy streams, with parallel reduction of flame retardants applied to date which, during pyrolysis and thermal transformations resulting in their decomposition, are transformed into toxic products. The nature of the invention is a modifier for expandable and expanded materials, especially polystyrene, characterised in that it contains ammonium bromide of between 0.5 and 35.0 parts by weight, triphenyl phosphate of between 0.3 and 18.0 parts by weight, benzyl benzoate of between 0.7 and 15.5 parts by weight and calcium chloride of between 1.0 and 100.0 parts by weight in proportion to the mass of its other components.

Preferably, according to the invention, the calcium chloride applied in the modifier is a hexahydrate. Preferably, according to the invention, the calcium chloride occurs in solid form or in the form of a water solution or water suspension.

The modifier restricts the commencement of the burning of styrene polymer, and its addition makes it possible to considerably enhance the thermal resistance of expanded styrene polymer and restricts the transformation of expanded styrene polymer into the liquid phase (flowing, trickling) and also has an effect on increasing the ignition temperature and electrical conductivity of the styrene polymer. Owing to the modification of expanded and expandable styrene polymers through the application of the fire retardant according to the invention, energy streams are generated which offer the possibility to utilise "nano" phenomena with respect to the expanded polymer surface; as a result, the radicals and/or atoms produced are occluded on the dendritic surface of the expanded styrene polymer in elementary quantity particularly with respect to nitrogen and/or carbon dioxide in statu nascendi which leads to the neutralisation of energy centres generated by the styrene polymer and the modifier according to the invention.

On the surface of the modified expandable and expanded material, especially polystyrene, through the application of the modifier according to the invention, energy centres generated by the polymer are neutralized, especially in the form of electrical friction charges with a known (+ or -) like sign which is an abhesive bridge for protective layers on the modified styrene polymer surface and the concerned and, hence, electrostatic neutralisation, homogenization and adhesive activation of the styrene polymer, especially the expandable or expanded polymer, occur. It was unexpectedly found, that a result of the application of the modifier according to the invention to expandable and expended materials, especially polystyrene, may also be an improvement in their thermal resistance (reduction in the lambda coefficient), mechanical characteristics (resistance to compression, elasticity) and elastic recovery caused e.g. by the expansion of the styrene polymer.

Owing to the application of calcium chloride in the modifier according to the invention it was unexpectedly found, that the compositions for the modification of EPS were ^' homogenised, electrical conductivity increased, electrical charges were propagated and intercrystalline water was exuded, which resulted in the cooling of the surfaces of modified expanded polystyrene materials during the operation of a heat stream. Unexpectedly, owing to the application of the modifier according to the invention, in the modified expanded polystyrene materials, the surfaces of expanded EPS granules developed; after a panel was cut, they had very advantageous geometric characteristics of increased friction coefficient (grip) and the possibility of favourable storage (retention) of adhesive preparations (e.g. glues) limiting voids between the surface of e.g. an EPS panel and the protected plane (e.g. a wall).

The application of the agent according to the invention, intended for modifying expandable and expanded materials, especially polystyrene, reduced the flammability and enhanced the thermal resistance of EPS, and its resistance to ultraviolet radiation, ozone and other adverse weather conditions, and stabilised the impact on the basic EPS parameters (lambda coefficient, compression, tightness).

The modifier according to the invention is presented in more detail in preferable exampled of its production which, however, do not restrict its scope; the preferable proportions between the components of the modifier according to the invention, in parts by weight, are shown in the illustrative table below:

The following are used in the modifier, according to the invention: - FLOVAN BU® is the trade name of the chemical agent produced by Huntsman Textile Effects with its seat in Germany, and its chemical composition is as follows:

Ammonium bromide of: 50-75 % by weight.

- PYROVATEX EXP® is the trade name of the chemical agent produced by Huntsman Textile Effects with its seat in Germany, and its chemical composition is as follows:

triphenyl phosphate of: 1 .0 - 2.5 % by weight,

benzyl benzoate of: 2.5 - 5.0 % by weight.

- hydrated calcium chloride produced by Zaktad Produkcyjny Soda Ma_twy with its seat in Inowrocfaw, Poland.

Example 1

The following are introduce into a metal vessel with a mixing arm: 100 kg of PYROVATEX EXP®, 30 kg of FLOWAN BU® and 40 kg of calcium chloride hexahydrate in the form of a 30% water solution; after homogenisation at a temperature of 20°C, with the mixing arm set to motion at a tangential velocity of 60 rev/min, during 20 minutes, about 130 kg of the preparation according to the invention is obtained to modify expanded polystyrene with the well-known method before or after expansion.

Example 2

The following are introduce into a metal vessel with a mixing arm: 100 kg of PYROVATEX EXP®, and 30 kg of FLOWAN BU®, 20 kg of calcium chloride hexahydrate in the form of powder with granule size of 55 pm; after homogenisation at a temperature of 20°C, with the mixing arm set to motion at a tangential velocity of 60 rev/min, during 20 minutes, about 150 kg of the preparation according to the invention is obtained to modify expanded polystyrene with the well-known method before or after expansion.

Example 3

The following are introduce into a metal vessel with a mixing arm: 100 kg of PYROVATEX EXP®, 30 kg of FLOWAN BU® and 50 kg of calcium chloride hexahydrate in water form of a 40 % paste and, after homogenisation at a temperature of 20°C, with the mixing arm set to motion at a tangential velocity of 60 rev/min, during 20 minutes, about 180 kg of the preparation according to the invention is obtained to modify expanded polystyrene with the well-known method before or after expansion.

Example 4

The following are introduce into a metal vessel with a mixing arm: 100 kg of PYROVATEX EXP® and 50 kg of a 10% water solution of calcium chloride; after homogenisation at a temperature of 20°C, with the mixing arm set to motion at a tangential velocity of 60 rev/min, during 20 minutes, about 150 kg of the preparation according to the invention is obtained to modify expanded polystyrene with the well-known method before or after expansion.

The modifier according to the invention can be introduced as a modifying flame retardant and a technological agent at any stage of the processing of the styrene polymer with well-known methods, i.e.: into styrene polymers to be expanded; into styrene polymers after expansion; directly into styrene polymers before seasoning; into styrene polymers at the stage of seasoning (during which porophore is exchanged with air) or into expanded EPS immediately before it is put into the block-forming machine and before block-forming.

The modifier according to the invention in the form of a water solution of 10 parts by weight with respect to the styrene monomer may also be applied as an addition during suspension polymerisation where complete preparation of the polymer is intended. The proportions between the different components of the modifier according to the invention are:

water of 20 parts by weight, PYROVATEX ^® EXP of 100 parts by weight, FLOVAN BU ^® of 30 parts by weight, calcium chloride of 25 parts by weight or: water of 20 parts by weight, PYROVATEX ^® EXP of 100 parts by weight, calcium chloride of 25 parts by weight

Modification of styrene polymers with the modifier according to the invention improves intregranular adhesion, reduces porosity, gas permeability, reflection of sunrays, particularly within the range of 300, 400 nm.