SI8211435A8 - Process for manufacturing of self-extinguishing expansive polystirene particles - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION

IPC: C 08L 25/04

The present invention relates to a process for the preparation of self-extinguishing expandable polystyrene particles having improved processing capability.

More specifically, the present invention relates to a process for the preparation of self-extinguishing expansive polystyrene particles useful for the production of molded bodies, in particular large-sized blocks having a high sintering rate, a uniform cellular structure with closed and non-permeable cell walls, small shrinkage and relative short holding time in the mold.

TECHNICAL PROBLEM

Known self-extinguishing polyethylene particles exhibit a strong shrinkage in the processing of objects made from them, which prevents objects with predetermined dimensions from being obtained, as well as the loss of a large proportion of the expansion agent during pre-expansion, resulting in shaped objects having small concentrations of residual expansion agent and low sintering due to low design pressure. A technical problem to be solved in the design of polystyrene particle bodies is therefore to improve the properties of the polystyrene particles used in the design. This problem is solved by the proposed process of the invention.

BACKGROUND OF THE INVENTION

As is known, it is possible to obtain styrene-based molded bodies of styrene by forming polymer particles containing gaseous or liquid expansion means in closed and not airtight molds by operating at a temperature higher than the boiling point of the expansion agent and higher than softeners of polymeric material.

In accordance with the customary mode of operation, pre-expanding polymer particles containing the expansion medium are first heated (pre-expanded) in a container, either closed or opened to a predetermined apparent density, and then after a suitable maturation time (about 24 hours). further expanded by heating (molding) in a non-airtight and pressure-resistant mold.

The consequence of such heating is that due to the limited space available, the particles sinter, forming a body that has the shape and dimensions of the cavity of the mold used.

After molding, it is allowed to cool the molded body in the mold for a sufficiently long time to limit the deformation of the molded body after removal from the mold.

Because the expanded plastic material is a material with excellent thermal insulation, relatively long residence times in the mold are required to cool the molded body.

In addition, styrene expansive polymers containing a self-extinguishing halogen-containing organic compound show strong shrinkage of shaped objects, making it impossible to obtain molded bodies with predetermined dimensions. A further drawback of these examples is that during the pre-expansion stage, they lose a large percentage of the expansion agent, so that the resulting molded bodies exhibit a low sintering rate due to the low concentration of the remaining expansion agent and therefore low design pressure.

In addition, the expanded particles have a cellular structure with very small cells, and the cell walls are punctured or open so that they do not allow high pressures to be reached during molding.

According to U.S. Pat. 4 029 614 it is possible to obtain molded expanded bodies based on high-sintering, low-shrinkage polystyrene particles by incorporating an amine having no oxyalkylated groups and having the general formula ^^, in which Ηη is an aliphatic or cycloaliphatic radical containing 4 to 20 carbon atoms, R ₂ is hydrogen or an aliphatic or cycloaliphatic radical containing 1 to 15 carbon atoms, and R ^ is hydrogen or an aliphatic or aromatic radical, which contains 1 to 15 carbon atoms, except that when R _n and R are both hydrogen, Βη contains 6 to 20 carbon atoms.

According to U.S. Pat. 4 192 922 achieved the same results using the 2,4-diamino-1,3,5-triazine derivative.

The experiments carried out by the applicant showed that none of the above mentioned compounds had satisfactory results, in particular as regards sintering and shrinkage of the products.

Description of solution to a technical problem with implementation examples

In accordance with the present invention we found to exhibit styrene polymer, containing an expansion agent, and we have made self-extinguishing by adding a conventional self-extinguishing organic compound containing a halogen, a small shrinkage during cooling, a better ^- sintering, the higher molding pressure, best times of cooling , cell surfaces with larger diameter cells with a small proportion of open or punctured cell walls and a homogeneous cellular structure if they contain an embedded small amount of 2,4,6-triamino-1,3,5-triazine having the general formula

in which at least one of the radicals R ^, R ^, R _& , R ?, βθ and R ^ is hydrogen and each independently of one another may be a hydrogen "alkyl radical containing 1 to 20 carbon atoms in which vi

as the case may be, a hydrogen atom in position (jj substituted by a 2,4,6triamino-1,3,5-triazine radical, a cycloalkyl radical containing 5 to 12 carbon atoms, or an aryl radical containing 6 to 18 carbon atoms, wherein these include alkyl, cycloalkyl or aryl radicals, optionally functional groups such as halogens, hydroxyls, carboxyl groups and esters.

Thus, the present invention is a process for preparing particles of homo- and styrene copolymers containing an expansion agent, a halogen-containing self-extinguishing organic compound, and 0.0001 to 0.1 wt. % calculated on the polymer of the 2,4,6-triaraino-1,3,5-triazine derivative having the above general formula (I).

Expansive particles according to the present invention can be obtained by polymerization, preferably in aqueous suspension, styrene either alone or in a mixture with one or more copolymerizable comonomers in the presence of a halogen-containing self-extinguishing organic compound and expansion agent, by means of a prostatic radical initiator at a temperature exceeding 80 ° C and by the addition of a 2,4,6-triamino 1,3,5-triazine derivative having the above general formula (I), before or during polymerization.

In particular, said 2,4,6-triamino-1, J, 5triazine derivative, the amount of which is preferably less than the amount of the halogenated organic compound, can be added to either the organic phase or the aqueous phase or the reaction mixture before or during polymerization.

The most appropriate amount of 2,4,6-triamino 1,3,5-triazine derivative to be added in each case depends on the amount and type of halogenated organic compound added to the polymer, as well as the temperature profile that it is used during polymerization.

This amount, which is always in the range of 0.0001 to 0.1%, can easily be determined by simple experiments.

Polymerization, addition of expansion agent, preexpansion of expansive particles, maturation and conversion of>

The expanded and matured particles into molded bodies are carried out according to techniques well known to the person skilled in the art and described in detail, e.g. in Bigid Plastic Foams by T.N. Ferrigno, Beinhold Publishing Corp., New York, USA (1963).

i

Normal suspension can be used to stabilize the suspension

And o

inorganic suspending agents, such as tricalcium phosphate, barium sulfate, zinc oxide, etc., or protective organic colloids such as poly-N-methyl-N-vinyl acetamide, polyvinyl alcohol, methyl cellulose, polyvinylpyrrolidone, etc. The resulting polystyrene particles were dried at a temperature between 10 and 50 ° C for 30 minutes to 20 hours.

In the present description and in the claims, styrene copolymers are intended to mean both styrene homopolymers and styrene copolymers with other vinyl and / or vinylidene monomers containing at least 50% by weight of chemically bound styrene.

Some examples of such comonomers are α-methyl-styrene, balogenated styrene at the core, such as 2,4-dichloro-fltirene, acrylonitrile, methacrylonitrile, α-β-unsaturated carboxylic acid esters with alcohols containing 1 to 8 carbon atoms, such as esters acrylic and / or methacrylic acids, N-vinyl compounds such as vinyl carbazole, etc. Styrene copolymers also include copolymers containing, in addition to styrene and possibly the above-mentioned vinyl and / or vinylidene copolymers, small amounts of monomers containing two double bonds, such as e.g. divinylbenzene.

Expansive polystyrene particles obtained by the present invention contain, as expansion agents, conventional gaseous or liquid organic compounds which do not dissolve but expand in the polymer and whose boiling point is lower than the softening point of the polymer. Some examples of particularly suitable expansion agents are aliphatic hydrocarbons, either alone or in a mixture of 2 to 6 carbon atoms, such as propane, butane, n-pentane, iso-pentane, hexane, cyclohexane, etc., further halogenated derivatives aliphatic hydrocarbons containing from 1 to 5 carbon atoms as various chloro and fluoro derivatives of methane, ethane and ethylene, such as dichloro-difluoro-methane, 1,2,2-trifluoro-1, '1,2-trichloroethane etc.

The expansion agent is used in an amount of from 5 to 15 wt. and preferably 5 to 9 wt. % by polymer.

Examples of self-extinguishing halogen-containing organic compounds that can be used in the styrene polymers of the present invention are oligomers of butadiene or isoprene, which are fully or partially brominated, and have an average polymerization rate of between 2 and 20, such as e.g. brominated 1-vinyl-cyclohekeen-J, brominated cyclo-octa-1,5-diene, brominated cyclododecyl-1,5,9-triene, brominated polybutadiene having a degree of polymerization between 3 and 15 ", etc.

Similarly effective are halogenated compounds belonging to other classes of substances, such as brominated phosphoric acid esters, such as tri- (2,3-dibromopropyl) phosphate, alkyl phenyl esters brominated in the core, such as penta-bromo-phenyl alkyl ether, pentabromo -mono-chloro-cyclohexane or other cyclohexanes containing at least three bromine atoms, etc. .

Self-extinguishing halogen-containing organic compounds are present in an expandable styrene polymer in an amount of 0.4 to 3% by weight. % by polymer.

In addition to halogenated compounds, known synergistic agents, preferably organic peroxides, such as di-t-butyl peroxide, di-cumyl peroxide, etc. can be used in conventional amounts.

Examples of 2,4,6-triamino-1,3,5-triazine derivatives useful in the present invention are:

- N-phenyl-2,4,6-triamino-1,3,5-triazine,

- N-dodecyl-2,4,6-triamino-1,3,5-triazine,

- N-octadecyl-2,4,6-triamino-1,3,5-triazine,

- NyN * -di-phenyl-2,4,6-triamino-1,3,5-triazine,

- N, N ', N'-tri-phenyl-2,4,6-triamino-1,3,5-triazine,

- N-cyclohexyl-2,4,6-triamino-1,3,5-triazine,

- 1,6-di- (2,4,6-triamino-1,3,5-triazine) hexane.

Mixtures of the above compounds are also useful.

In addition to the above-mentioned compounds and agents, styrene expansive particles obtained according to the present invention may contain other additives in normal quantities, such as plasticizers, stabilizers, colorants, antistatic agents, anti-caking agents, to avoid pre-exposure clumps, etc.

The following examples are given to better explain the inventive concept of the present invention and to facilitate its implementation, but are not intended to limit the invention.

EXAMPLES 1 to 7

In a 100 liter stainless steel reactor previously rinsed with nitrogen, a series of polymerizations are carried out in an aqueous suspension of the mixture, with the following composition:

- deionized water 35 kg - tricalcium phosphate 30 Mr Rücker -0.1 N sodium hydroxide 18 ml - styrene monomer 35 kg - Dibenzoyl peroxide 143,5 Mr Rücker - tert.butyl perbenzoate 52,5 Mr Rücker - dicumyl peroxide 70 Mr Rücker - 1,2,5,6,9,10-hexabromo-cyclododecane 210 Mr Rücker - sodium metabisulphite 0.56 Mr Rücker

- a compound of the type and in an amount as listed in the following table.

The polymerization is carried out at temperatures varying between 85 ° and 120 ° C for a total time of 15 hours. 3.1 kg, calculated on the monomer, of the expansion agent consisting of a mixture of n-pentane and iso-pentane were added during the polymerization (mass ratio 70:30). After cooling to room temperature, filtration, washing with water and drying, the polymer is sieved to yield expansive polystyrene particles between 0.9 and 1.6 mm in diameter. These particles contain about 6 wt. % expansion agent.

- 11 The expansive particles thus obtained are introduced into a pre-expander, in which they are pre-expanded for about b minutes with steam from 95 to 100 ° C. The pre-expanded particles were allowed to mature in air at room temperature for about 24 hours. Pre-expanded and mature particles are placed in a block press * until a 100 x 100 x 50 cm mold is filled.

The design is carried out with a vapor pressure of 0.64 bar. We determine the block cooling time, which means the time it takes to drop after the vapor pressure inside the block has ceased to zero.

The shrinkage and sintering rate are determined at blocks 48 hours after design.

Both of these characteristics are evaluated on a 2 cm thick plate obtained from the central part of the block by cutting with hot wire.

The shrinkage is determined on the basis of the difference in length and width of the plate compared to the corresponding dimensions of the mold.

The sintering (8) represents the percentage of expanded particles that crumbles when the plate is broken, and is determined by the equation:

_ L a + (50 -. B ₂

100 in which L is the length of sintering sections 70% but the average percentage of broken particles in section L and b is the average percentage of broken particles in section (50% - L) having sintering <(70%).

- ¹ 3 The following table lists the characteristics of molded blocks obtained with expansive particles containing various constituents.

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- L 1 Q> Λ1 o KO r- m ir \ o LF \ Oh TO ¹ a m rc 'M' r · Φ • r; > rt Oh o Oh o a \ o o co tC \ ir \ m KO KO KO who p rt • d 03 • o 05 Pi £ 3 <n -P CO., LTD B σκ • 3- Lf \ ICK -V KO LT> 0 a rt r » · " e * · * · «R- < -P Ai rt «J sf cane CCK M · m m m o A4 r * T— r " t— t— T ~ r * , 0 H co 1 O £> 4 05 • o rt Φ TO m (0 £ 3 r- and co CM CO., LTD KO st r- £ 3 > -P * - CM CM CM rt m rt CO -rl > O B £ 2 • rt • H 1 rt rt CO CO., LTD H Ai £> σ> ΝΛ [> - σκ KO CM Lf \ CO., LTD ω 00 oo Oh o σκ B t »>  r » e · e » * * » e » »» r » • rl Oh Oh Oh o v r o ra w rt A4 <3 a, 05 H P S-PH <0 i rt rt M · 00 CM Φ o o o Oh Oh Oh ra B 1 o o o o o o • t) Oh <* r · r * r * e ra φ rt o o o o o o to H o s bos 1 t 1 CO., LTD o o o _ rt 1 1 rt rt rt rt rt rt rt • rl KO rt kD • rl • H · Η • rl Ή • rt * rl Ό 1 1 • rl «* t » 1 B H 1 B N 1 B « Oh ΟΙΛ B • 4 C0 H 05 C0 H 05 C0 i — t 05 CD cape - C0 r » 1 -rt • rt «rt« rt rl «rl * rl • rl »rt * rt £ q • rlK> CM o o rt rt o rt rt o rt rt 05 1 B -rt • H 1 rt-p Φ-P -P Φ -P -P Φ -P -P CO., LTD -P 05 V -rl Oh H * rl 1 T) 1 1 t) i i • cape and i rt ra • rl 1 N Φ • Cape B Lf \ COKO ΙΛ <0kOU \ COKO | £ \ m rt You H 05 tJ rt 05 - r » p ** e .p 9 * · * 1 rl -H Oh φ • Cape K> AJ4 rA Ai 4 fO A14tO o 4 rt rt You «H cape - o ♦ O - - o * »· * Q -Φ -P 1 1 -P v 1 CM K- I CM v 1 CM V cmh i rt 52. 1 1 & 1 1 & 1 1 & 1 1 rt φ T ~ CM m • v Lf \ KO r- B • H rt > 1 M La.

The best way to do it economically exploitation of the invention In a 100 liter stainless steel reactor steel, which pre-rinse it with nitrogen, perform polymerization in vod no suspension of the mixture, with the following composition - deionized water 35 kg - tricalcium phosphate 30 Mr Rücker - 0,1 N sodium hydroxide 18 ml - styrene monomer 35 kg - Dibenzoyl peroxide 143,5 Mr Rücker - tert.butyl perbenzoate 52,5 Mr Rücker - dicumyl peroxide 70 Mr Rücker - 1,2,5,6,9,10-hexabromo-cyclododecane 210 Mr Rücker - sodium metabisulphite 0.56 S - N-octadecyl-2,4,6-triamino-1,3,5-triazine 1.4 Mr Rücker

The polymerization is carried out at temperatures varying between 85 ° and 120 ° C for a total time of 15 hours. 3.1 kg, calculated on the monomer, of the expansion agent consisting of a mixture of n-pentane and iso-pentane were added during the polymerization (mass ratio 70:30). After cooling to room temperature, filtration, washing with water and drying, the polymer is sieved to yield expansive polystyrene particles between 0.9 and 1.6 mm in diameter. These particles contain about 6 wt. % expansion agent.

The expansive particles thus obtained are introduced into the pre-expander, in which they are pre-expanded with a temperature of 95 to 100 ° C for about 5 minutes. The pre-expanded particles were allowed to mature in air at room temperature for about 24 hours. Pre-expanded and mature particles are placed in a block press until a 100 x 100 x 50 cm mold is filled.

The design is carried out with a vapor pressure of 0.64 bar. We determine the block cooling time, which means the time it takes to drop after the vapor pressure inside the block has ceased to zero.

Claims (4)

PATENT APPLICATIONS A process for the preparation of self-extinguishing expandable polystyrene particles having a size from 0.1 to 10 mm, containing an expansion agent, a halogen-containing self-extinguishing organic compound, and from 0.0001 to 0.1 wt. %, calculated on polymer, derives 2,4,6-triamino-1,3,5-triazine having the general formula in which at least one of the radicals, Rg, R ?, Rg and Rg is hydrogen and each of them independently of one another may be hydrogen, alkyl a radical containing from 1 to 18 carbon atoms in which the hydrogen atom is optionally substituted with a 2,4,6-triamino-1,3,5-trazine radical * a cyclohexyl radical or a phenyl radical, to polymerize styrene either alone or in admixture with one or more vinyl and / or vinylidene monomers containing at least 50 wt. % chemically bound styrene such as 2,4-dichloro-styrene, acrylonitrile, methacrylonitrile, esters -unsaturated carboxylic acids with alcohols containing 1 to 8 carbon atoms, such as acrylic and / or methacrylic acid esters, N-vinyl compounds, such as vinyl carbazole, in the presence of a halogen-containing self-extinguishing organic compound such as butadiene or isoprene oligomers, fully or partially brominated and having an average degree of polymerization between 2 and 20, such as brominated 1-vinyl-cyclohexene-3, brominated cyclo-octa-1,5-diene, brominated eclododecyl-1,5,9-triene, brominated polybutadiene having a degree of polymerization between 3 and 15 as well as brominated phosphoric acid esters such as tri- (2,3-dibromopropyl) phosphate, alkyl phenyl esters brominated in the core, such as penta-bromo-phenyl alkyl ether, penta-bromo -mono-chloro-cyclohexane or other cyclohexanes containing at least three bromine atoms, and expansion agents such as aliphatic hydrocarbons, either alone or in a mixture of 2 to 6 carbon atoms, such as propane, butane, n -pentane, iso-pentane, hexane, cyclohexane, halogenated derivatives watts of aliphatic hydrocarbons containing from 2 to 3 carbon atoms as various chloro and fluoro derivatives of methane, ethane and ethylene, such as dichloro-difluoro-raetane, 1,2,2-trifluoro-1,1,2-trichloroethane, with space radical to initiators such as organic peroxide, such as di-t-butyl peroxide, di-cumyl peroxide, and at a temperature above 80 ° C, and before or during polymerization, 2,4,6-triamino-1,3,5-triazine derivative is added, which has the above general formula (I). - ΐ92. The process according to claim 1, characterized in that the polymerization is carried out in aqueous solution. Method according to claim 1, characterized in that the proportion of expansion agent is from 3 to 15 wt. %. Process according to claim 1, characterized in that the proportion of the halogen-containing self-extinguishing organic compound is from 0.4 to 3 wt. % by polymer.