Styrene foaming polymeric compounds containing the carbon particles

FIELD: chemical industry; methods of production of the foaming styrene polymeric compounds containing the particles of carbon.

SUBSTANCE: the invention is pertaining to the present in the form of the granules of the foaming styrene polymeric compounds containing the carbon particles and having the low contents of pentane. The invention presents the description of the method of production of the foaming styrene polymeric compound, in which styrene is polymerized in the water suspension at presence from 0.1 up to 25 mass % of the graphite or smut particles and from 2.5 up to 5.5 mass % of pentane, all in terms of the monomers. After the water flushing, the produced mass is subjected to drying during less than 1 second by the air stream with the temperature from 50 up to 100°С. The invention also describes the granules of the styrene foaming polymeric compound with the bulked weight above 600 g/l. The granules contain from 0.1 up to 25 mass % of the particles of the graphite or the smut, and also the volatile foaming agent representing the mixture composed of from 2.2 up to 5.0 mass % of pentane and from 1 up to 10 mass % of the water, all in terms of the granules of the styrene foaming polymeric compound. The technical result of the invention is production of the granules of the styrene foaming polymeric compound with the high contents of the internal water at the low contents of pentane which possess the high capability to the foaming.

EFFECT: the invention ensures production of the styrene foaming polymeric compound granules with the high contents of the internal water and the low contents of pentane, which have the high capability to the foaming.

9 cl, 3 ex, 1 tbl

 

The invention relates to available in the form of granules containing carbon particles of expanded polymers of styrene with a low content of pentane.

Polystyrene known for a long time and has proven itself in many applications. The receipt of such a foam is a foam impregnated with a blowing agent granules of expandable polystyrene and subsequent bonding foam pellets and molded articles. An important area of application is the insulation in the construction industry.

Used for insulation of the foam slabs of expanded polymers of styrene have a bulk density of at least 30 g/l, as at such densities, thermal conductivity of the pellets of foam has a minimum. For reasons of economy of material, it is desirable to use for insulation, foam plate with low bulk weight, in particular ≤15 g/l Receipt of such foams is technically not cause problems. Foam plate with low density, however, have a very poor ability to insulation, so that they do not fulfill the requirements of the class thermal conductivity 035 (see German industrial standard DIN 18 164, part 1).

Known to decrease thermal conductivity of foams by the use of such materials as carbon black, metal oxides, metal powder or pigments. PA is entie application WO 98/51734, 98/51735, 99/16817 and EP-915 127 are available in the form of granules containing graphite particles of expanded polymers of styrene, and made of them the foams with low thermal conductivity.

Available on the market granules of expandable styrene polymer usually contain as a blowing agent pentane in an amount of from 6 to 7 wt.%, what takes place also in the examples contained in the above publications. For reasons of ecology are striving to keep the content of foaming agents based on hydrocarbons as low. For example, in US-A 5112875 describes a solution in which granules of expandable styrene polymer can be obtained by using foaming agents based on hydrocarbons in an amount of from 2 to 5.5 wt.%, if the polystyrene has a special distribution of molecular weight. Preferably at such a "low-pentanoic" products pentane content is from 3 to 4 wt.%. Similar granules of expandable styrene polymer, however, have the disadvantage of a low ability to foaming, i.e. one stage of foaming is unable to achieve a bulk weight approx. below 20 g/L. To do this, you need to add expensive aprivately polymer chain, for example dimeric α-methylsterol, or plasticizers, such as high hydrocarbons, or you want to apply the PSS is ing the technique of foaming, for example, pre-foaming under pressure or repeated foaming.

The patent US-A 5,096,931 describes foaming polymers of styrene, which as a foaming agent containing a mixture of water and C3up With6-hydrocarbon, and superabsorber, in particular partially crosslinked polyacrylic acid. This has the disadvantage that, due to the low pH values during the suspension polymerization is distorted and, in addition, there are branching polystyrene chain.

Application WO 99/48957 describes a method of obtaining containing water as the sole blowing agent of the styrene polymer by emulsion polymerization of styrene in the presence of carbon black or graphite, which act as an aid for the emulsification of water in a thin distribution in the suspended droplets of styrene. The obtained expandable polystyrene particles cannot, however, to foam in conventional devices pre-foaming of hot steam.

In the application WO 00/15703 describes the slightly foamed porous particles of expandable styrene polymer with a bulk weight of from 200 to 600 g/l, which contain the means of nucleinate, a maximum of 2 wt.% organic foaming agent such as pentane, and a maximum of 3 wt.% water, all calculated on the polymer, stiro the and. The porous particles should be produced on a separate stage of the way through the expansion.

The objective of the invention is to develop available in the form of granules of expanded polymers of styrene with a relatively low content of pentane, however, with a good ability to foaming, which can be easily processed into foams with low thermal conductivity.

The problem is solved containing graphite particles or carbon black expandable styrene polymer, which as a blowing agent contains, along with pentane in an amount of from 2.2 to 6 wt.% still from 1 to 10 wt.% water. This contains graphite particles or carbon black expandable styrene polymer in contrast to conventional polymer foaming styrene is not inclined to wypadaniu water during storage, even if the water content up to 4 wt.%.

Preferably granules of expanded polymers of styrene according to the invention contain from 2.5 to 5.0 wt.%, in particular from 3.0 to 4.0 wt.%, pentane and more than 3 to 8, in particular from 3.5 to 6 wt.% water.

Granules of expanded polymers of styrene virtually no pores and have a bulk density of more than 600 g/l, preferably more than 650 g/l and, in particular, more than 700 g/l

Expandable styrene polymer according to the invention contains, as the polymer matrix, in particular geopolitical or copolyme the s of styrene with up to 20 wt.%, in terms of weight polymers, Ethylenediamine of comonomers, in particular alkylthiol, divinylbenzene, alkynylaryl or α-methylsterol. Also possible are mixtures of polystyrene and other polymers, in particular rubber and simple Polyphenylene ether.

Polymers of styrene due to good capacity for expansion may have a relatively high viscosity in the range from 75 to 100 ml·g-1without the addition of plasticizer, which can lead to undesirable emissions.

The styrene polymer may contain the usual and known auxiliary agents and additives, such as flame retardants, seed, light stabilizers and antioxidants. Preferably the polymers do not contain styrene crosslinked or branched, having carboxypropyl polymers such as polyacrylic acid.

Suitable additives to reduce thermal conductivity are particles of carbon such as carbon black, and graphite. Suitable conventional varieties of carbon black, preferably fiery carbon black with a particle size of from 80 to 120 nm. Carbon black is added preferably in an amount of from 2 to 10 wt.%. Particularly well suited graphite, and preference is given to particles with an average size of from 0.5 to 200 μm, preferably from 1 to 25 μm, and in particular from 2 to 20 μm, a bulk weight of from 100 to 500 g/l and a specific surface area of from 5 to 20 m2 /, it Was found that there is a relationship between the average particle size of the graphite and the amount of water which is introduced into the foaming polymers of styrene. When the average particle size of 30 μm is introduced, for example, 2% water, with an average particle size of 10 microns is introduced approx. 4% water and when the particle size of 4 μm approx. 8%. Can be used natural graphite or powdered synthetic graphite. The graphite particles contained in the polymer of styrene in an amount of from 0.1 to 25 wt.%, in particular from 0.5 to 8 wt.%.

In one preferred form of execution of the invention expandable styrene polymer contains a flame retardant, in particular, on the basis of organic bromine compounds. Organic bromine compounds must have a bromine content ≥70 wt.%. Particularly suitable aliphatic, cycloaliphatic and aromatic bromine compounds such as hexabromocyclododecane, pentabromoethylbenzene, simple pentabromophenoxy ether.

The action of bromine flame retardants significantly improved by the addition of organic compounds with unstable carbon-carbon or oxygen-oxygen bonds. Examples of suitable synergists flame retardants are Dicumyl and dicumylperoxide. The preferred combination consists of 0.6 to 5 wt.% organic bromine compounds and 0.1 to 1.0 wt.% organic compounds with Nesta lname carbon-carbon or oxygen-oxygen bonds.

Granules of polymers of styrene according to the invention have an ordinary suspension polymerization of styrene, optionally together with 20%, in terms of its weight, of comonomers in the presence of from 0.1 to 25 wt.%, preferably, from 0.5 to 8 wt.% particles of graphite or carbon black and from 2.5 to 8, preferably from 3 to 5.5 wt.% pentane, all calculated on the monomers. Foaming agent may be added before or during the suspension polymerization.

The suspension polymerization is carried out preferably as described in the application WO 99/16817 - in the presence of two decaying at different temperature peroxides. Disintegrating at a lower temperature peroxide And should have a half-life period of 1 hour at 80 to 100°C, preferably from 85 to 95°With, while decomposing at a higher temperature peroxide In must have a half-life period of 1 hour at 110 to 140°C, preferably at 120 to 135°C. Preference is given in this peroxides such As that in the decay form the alkoxy group. As examples should lead tert.-butyl peroxy-2-ethylhexanoate, amyl-peroxy-2-ethylhexanoate, tert. butylperoxybenzoate, and tert.- butylperoxyisopropyl. Possible polymerization in the presence of dibenzoylperoxide.

As peroxide can be used In all conventional disintegrating when bringing the military high temperature peroxides. Preferred such that do not contain benzoline groups, if the obtained granules of expandable styrene polymer should not contain benzene. The preferred peroxides is so dicumylperoxide, as well as aliphatic or cycloaliphatic percetly or monoperoxyphthalate. Along with this can be used, for example, di-tert.-AMYLPEROXY.

The suspension polymerization is carried out expediently in two temperature stages. When this slurry is first heated for a maximum of 2 hours to a temperature of from 90 to 100°and peroxide And decomposes and initiates polymerization. After that, the reaction temperature allowed to rise, preferably at a speed ranging from 8 to 17°With in an hour and bring it to a temperature of from 120 to 140°C. This temperature is kept up until the content of residual monomers will not decrease less than 0.1%. At this temperature, decomposes peroxide Century This method to obtain expandable styrene polymer with a low content of residual monomers.

It was found that the stability of the suspension contributes to the fact that at the beginning of the suspension polymerization has a solution of polystyrene or, respectively, a suitable copolymer of styrene in the styrene or mixture of styrene and comonomers. Preferably the assumption of the solution is t 0,5-30, in particular from 3 to 20 wt.%-aqueous solution of polystyrene in styrene. This can be dissolved in the monomers fresh polystyrene, suitable apply the so-called boundary fractions that are eliminated as too big or too small granules when splitting a particle size distribution produced during the production of polymer of styrene. In practice the maximum fraction have a diameter of more than 2.0 mm, respectively, less than 0.2 mm Can also be used polystyrene recycling and Styrofoam recycling. Another possibility is that the pre-styrene polimerizuet to the degree of conversion of from 0.5 to 70%, and pre-primaryservername polymer finally polymerizing together with soot particles, respectively, graphite in an aqueous phase.

When suspension polymerization are mainly round granules with an average diameter in the range from 0.2 to 2 mm, in which soot particles, respectively graphite, homogeneous distributed. They are washed in a known manner and free from water on their surface.

It was found that granules of polymer foaming styrene with a water content according to the invention from 1 to receive 10% when used at least one, possibly several, of the following methods:

- when is olymerization must act only small cutting efforts i.e. at low power mixer mixing should be done relatively slowly;

the slurry should be heated quickly, preferably within 30 to 120 min to a temperature of from 90 to 100°C;

- the final temperature should be relatively high, preferably above 120°With, in particular, above 130°C;

- drying should be done relatively quickly.

Preferably the granules of expandable styrene polymer after washing is subjected to high-speed drying, i.e. within less than 1 sec in the air stream with a temperature of from 50 to 100°to remove adherent surface water. In that case, if the contents of the internal water is approx. more than 4 wt.%, on the surface of granules of expandable styrene polymer should be applied a coating that has a high hygroscopicity, such as sodium polyacrylate. With a too high water content there is a possibility that the storage of unwanted water vyparivat.

In case of prolonged storage, in particular, in open air, part pentane may evaporate from the pellets of the styrene polymer. It is significant that during the foaming process the content of the pentane is at least 2.2 wt.%.

Granules of expandable styrene polymer can be coated with conventional coatings, such as CTE is clear metal complex glycerol acroname and tankodesantniki silicates.

Another object of the invention is a method of producing pellets of a styrene polymer foams by foaming granules of expandable styrene polymer according to the invention, in which these granules at one stage foamed to a bulk weight below 200 g/l, preferably below 150 g/l, and in one or more of the following stages to loose weight below 50 g/l, preferably below 40 g/L. This is carried out by heating the granules of expandable styrene polymer and water vapor in the so-called pre-blowing agents.

Thus obtained pre-expanded granules can be processed into foam with a bulk weight of from 5 to 35 g/l, preferably from 8 to 25 g/l and, in particular, from 10 to 15 g/L. For this pre-foamed pellets are placed in unsealed form, process steam and weld in a molded product. After cooling, the molded product can be removed.

Example 1

In 419 kg of styrene dissolved 21 kg of polystyrene (PS brand 158 company BASF AG, DE) and homogeneous suspended 8.5 kg of powdered graphite (average particle diameter 30 mm) (firm Graphitic Kropfmuhl AG, DE) under the adulteration 0,34 kg of tert. butyl peroxy-2-ethylhexanoate, 2.1 kg of dicumylperoxide, and 2.9 kg of hexabromocyclododecane. Organic is ABC load in 485 l fully demineralized water in a sealed pot with mixer capacity of 1 m 3. The aqueous phase contains 1,16 kg of sodium pyrophosphate and 2.15 kg of Epsom salt. The reaction mixture in low heat stirring for 75 minutes to 95°C. After that the reaction mixture is heated for 4 hours to 132°C, and after 2 hours add 5,8 KGO emulsifier To 30/40 (by Bayer AG, DE) and after approx. 2.5 hours 25 kg of pentane. In conclusion, at a temperature of 137°To produce polymerization. Granules of expandable polymer is washed and dried fast drying. The viscosity of the polystyrene is 83 ml ·g-1.

Sieved fraction of granules with size from 1.6 to 2.5 mm, the content of pentane and internal waters which determine. Then the granules slowly churn water vapor for 3 minutes and measure bulk density. Tenoplasty granules weld in a conventional machine for moulded products. Measure the time until the pressure drop, which was formed after the steam supply for welding pellets of the molding product (retrieval time).

Comparative example 2V

Example 1 is repeated, with the expandable polystyrene granules are dried for 8 hours with hot air to a temperature of 50°C.

Example 3

Example 1 is repeated, in this case, applying graphite with an average particle size of 10 μm and add only 17.5 kg of pentane.

Table 1 shows the results.

Approx. No.Bulk density (pellets) g/lThe content of pentane (granules) wt.%The water content (granules) wt.%Bulk density (foam material) g/lRetrieval time (molding product) s.
17214,5to 1.8616,157
2V7184,50,1921,387
37303,54,5018,951

1. A method of producing granules of expandable styrene polymer, characterized in that the styrene polymerizing in aqueous suspension in the presence of from 0.1 to 25 wt.% particles of graphite or carbon black and from 2.5 to 5.5 wt.% pentane, all calculated on the monomers, and after washing is subjected to drying in less than 1 with an air stream with a temperature of from 50 to 100°C.

2. Granules of expandable styrene polymer obtained by the method according to claim 1 with a bulk weight above 600 g/l, containing from 0.1 to 25 wt.% particles of graphite or carbon, and volatile foaming agent composed of a mixture of 2.2 to 5.0 wt.% pentane and 1 to 10 wt.% water, all in terms of granules of expandable styrene polymer.

3. Granules according to claim 2, characterized in that they have a bulk density above 650 g/L./p>

4. Granules according to claim 2, characterized in that they contain from 2.5 to 5.0 wt.% pentane and more than from 3 to 8 wt.% water.

5. Granules according to claim 2 or 3, characterized in that they contain from 3.0 to 4.0 wt.% pentane and from 3.5 to 6 wt.% water.

6. Granules according to one of claim 2 to 5, characterized in that they contain from 0.5 to 8 wt.% graphite with an average particle size of from 1 to 25 microns.

7. Granules according to one of claim 2 to 5, characterized in that they contain from 2 to 10 wt.% fiery carbon black with a particle size of from 80 to 120 nm.

8. Granules according to one of claim 2 to 7, characterized in that the viscosity of the polymer matrix has a range of 75 to 100 ml/year

9. Granules according to one of claims 1 to 7, characterized in that they additionally contain from 0.6 to 5 wt.%, in terms of polymer, organic bromine compounds with bromine content greater than or equal to 70 wt.% as a flame retardant, and from 0.1 to 1.0 wt.%, in terms of polymer, organic compounds with unstable carbon-carbon or oxygen-oxygen bonds as a flame retardant synergist.



 

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