Porous polymer particles
Abstract
This record has no abstract on file.
Term
Term ended
Expired 14 September 2019, 7 years ago.
- Priority
- Filed
- Granted
- Expired
- Today
11 claims: 3 independent, 8 dependent
- 1Porowate cząstki poliwinyloarenów, wytwarzane z niespienionych cząstek polistyrenowych, znamienne tym, że te porowate cząstki poliwinyloarenów mają budowę porów pozwalającą na nasycenie cząstek nieszkodliwym środkiem spieniającym i gęstość pozorną do 600 do 200 kg/m 3 i te porowate cząstki zawierają 0,01 do 3% wagowych, w stosunku do ilości poliwinyloarenu, środka zarodkującego i 2,0% wagowe lub mniej, w stosunku do ilości poliwinyloarenu, lotnego organicznego środka spieniającego, a porowate cząstki wykazują wzrost objętości, który wynosi 1,5 do mniej niż trzykrotnego w porównaniu z objętością tych niespienionych cząstek, przy czym środek zarodkujący jest wybrany z grupy obejmującej węglan wapnia, siarczan baru, siarczan wapnia, talk, glinka, krzemian magnezu, cząstki krzemionki bezpostaciowej, zeolity, ziemię okrzemkową, tlenek magnezu, tlenek tytanu, mieszaniny wodorowęglanu sodu z kwasem cytrynowym, związki organiczne zawierające brom, związki naftalenowe, policykliczne węglowodory aromatyczne, sadzę, koks, węgiel odbarwiający, grafit i pył diamentowy, parafinę, pochodne kwasów tłuszczowych, cząstki polichlorku winylu, cząstki polipropylenu, cząstki polietylenu, cząstki kauczuku akrylonitryl/butadien/styren, cząstki kauczuku styrenowo-butadienowego, cząstki kopolimeru styren/bezwodnik maleinowy, cząstki celulozy, cząstki skrobi modyfikowanej, sulfobursztyniany bis-alkilowe, C8-C20-karboksylany sorbitolu, sulfoniany C8-C20-alkiloksylenowe sorbitolu, woski polietylenowe o wagowo średnim ciężarze cząsteczkowym 500 do 5000, oraz ich mieszaniny, a lotne organiczne środki spieniające są wybrane z grupy obejmującej węglowodory C2-C6, chlorowcowane węglowodory, oraz ich mieszaniny.
- 2Cząstki według zastrz. 1, znamienne tym, że mają gęstość pozorną do 530 do 250 kg/m 3 .
- 3Cząstki według zastrz. 1 albo 2, znamienne tym, że zawierają mniej niż 3,0% wagowych w przeliczeniu na ilość poliwinyloarenu, wody.
- 4Cząstki według zastrz. 1, znamienne tym, że poddane działaniu pary nasyconej pod ciśnieniem powyżej ciśnienia atmosferycznego do osiągnięcia końcowej temperatury 105°C przez 30 sekund, spieniają się do gęstości pozornej, która jest najwyżej trzykrotnie niższa niż do.
- 5Cząstki według zastrz. 1, znamienne tym, że budowa porów ma pory o średniej wielkości 5 do 100 μm.
- 6Cząstki według zastrz. 1, znamienne tym, że poliwinyloarenem jest polistyren.
- 7Sposób wytwarzania porowatych cząstek polistyrenowych, znamienny tym, że spieniające się cząstki polistyrenów, zawierające środek zarodkujący i od 0,5 do 4% wagowych C2-C6 organicznego środka spieniającego w stosunku do polistyrenu, poddaje się wstępnemu spienianiu do gęstości pozornej 600 do 200 kg/m 3 do utworzenia w tych porowatych cząstkach polistyrenów budowy porów pozwalającej na nasycenie cząstek nieszkodliwym środkiem spieniającym, a porowate cząstki polistyrenów zawierają 2% wagowe lub mniej C2-C6 organicznego środka spieniającego, w stosunku do ilości polistyrenu, przy czym środek zarodkujący jest wybrany z grupy obejmującej węglan wapnia, siarczan baru, siarczan wapnia, talk, glinka, krzemian magnezu, cząstki krzemionki bezpostaciowej, zeolity, ziemię okrzemkową, tlenek magnezu, tlenek tytanu, mieszaniny wodorowęglanu sodu z kwasem cytrynowym, związki organiczne zawierające brom, związki naftalenowe, policykliczne węglowodory aromatyczne, sadzę, koks, węgiel odbarwiający, grafit i pył diamentowy, parafinę, pochodne kwasów tłuszczowych, cząstki polichlorku winylu, cząstki polipropylenu, cząstki polietylenu, cząstki kauczuku akrylonitryl/butadien/styren, cząstki kauczuku styrenowo-butadienowego, cząstki kopolimeru styren/bezwodnik maleinowy, cząstki celulozy, cząstki skrobi modyfikowanej, sulfobursztyniany bis-alkilowe, PL 199 952 B1 C8-C20-karboksylany sorbitolu, sulfoniany C8-C20-alkiloksylenowe sorbitolu, woski polietylenowe o wagowo średnim ciężarze cząsteczkowym 500 do 5000, oraz ich mieszaniny.
- 8Sposób według zastrz. 7, znamienny tym, że spieniające się cząstki polistyrenu wytwarza się w polimeryzacji zawiesinowej, w której styren polimeryzuje się w wodnej zawiesinie w obecności środka zarodkującego i 0,1 do 1% wagowego inicjatora wolnorodnikowego, przy czym C2-C6 organiczny środek spieniający dodaje się przed, podczas lub po polimeryzacji, w ilości od 0,5 do 4% wagowych w stosunku do ilości styrenu, do uzyskania spieniających się cząstek polistyrenu.
- 9Sposób według zastrz. 7 albo 8, znamienny tym, że wstępne spienianie cząstek polistyrenu prowadzi się przez wystawienie ich na działanie gorącego powietrza.
- 10Sposób według zastrz. 9, znamienny tym, że gorące powietrze ma temperaturę od 90 do 200°C.
- 11Zastosowanie cząstek określonych w zastrz. 1 do 6 do wytwarzania cząstek spienionych i wyrobów piankowych.
Independent claims11
102 paragraphs in 4 sections, as filed
Description of the invention
The present invention relates to porous polyvinylarene particles, their use, and a method for producing porous polystyrene particles. These porous polyvinylarene particles can be expanded into foam articles.
It has been known for many years that polyvinylarene particles, such as polystyrene, can be rendered pore-forming and that the particles thus obtained can be used in the preparation of foam articles. For example, US Pat. No. 2,681,321 discloses a method in which polystyrene particles are treated with liquid hydrocarbons in such a way that the liquid hydrocarbon is dispersed in these particles. The particles so produced typically contain 4 to 8 wt% of a liquid hydrocarbon blowing agent, such as butane, n-pentane or mixtures of pentanes. These particles can be expanded into beads of reduced density. Apparent densities for packaging particles typically are in the range of 20 to 60 kg / m3<sup>3</sup>. After foaming, the particles are melted in a steam-heated mold and foam products of the desired shape are obtained.
One factor that influences the expansion of the polystyrene particles is the amount of hydrocarbon blowing agent. The Encyclopedia of Chemical Technology, Kirk Othmer, 3rd Ed., Vol. 21, p. 838 states that the density of particles containing 5.7 wt% n-pentane is typically 1080 kg / m3.<sup>3</sup>; for comparison - the density of pure polystyrene beads is 1050 kg / m<sup>3</sup>, while the calculated density of a normal mixture in which n-pentane is dissolved in polystyrene is 1020 kg / m<sup>3</sup>. If all pentane were in the voids, the calculated density would be 1120 kg / m3<sup>3</sup>. This suggests that some of the hydrocarbon blowing agent is in small voids in the polystyrene. One skilled in the art will appreciate that the above densities are particle densities that can be converted to apparent densities. Particle density 1080 kg / m<sup>3</sup> corresponds to an apparent density of about 720 kg / m3<sup>3</sup>.
The disadvantage of this solution is that the volatile organic blowing agent can evaporate from the particles, especially the voids, during their transport and storage. When the particles are transported and / or stored at different temperatures and / or at different times, the amount of pentane retained, for example, can change significantly. In addition to extraordinary precautions to be taken during transport, such as gas-tight packaging, be aware that such a change may have an impact on the foam produced after foaming.
Moreover, the foaming process itself can also cause the emission to the environment of organic blowing agents contained in the non-foamed particles. In order to reduce these emissions, a sophisticated device has been developed in which the emitted blowing agent is collected for further treatment, e.g. combustion. This device is installed in the equipment used by the end user of the particles, e.g. the customer who produces the foam products. This requires additional expertise and additional expenditure on the part of these recipients.
From GB 1,106,143 and WO 98/01489, expandable particles are known in which water is used as the blowing agent. While such particles overcome some of the problems mentioned, one drawback of such particles is that water is less volatile than commonly used blowing agents. Therefore, special measures must be taken to stimulate the evaporation of water in order to obtain adequate foamability. In GB 1 106 143 it is noted that an additional volatile organic blowing agent is required to obtain a satisfactory expandability.
Thus, the inventive idea comes down to producing high density expandable polyvinylarene particles which could be expanded with a non-harmful blowing agent. However, the known high-density particles still contain a relatively large amount of volatile organic blowing agent. In this connection, reference can be made to US Pat. No. 3,973,884, in which relatively high density polymer beads are described. According to this description, less pentane or other blowing agent can be used to produce high-density polystyrene particles than in low-density particles. However, it is further stated that the difference is small and that in the particles intended for low densities the pentane content may be in the range of 6-7.2% by weight, while the polystyrene particles intended for high densities contain 5.8 to 7.0% by weight. pentane. When these particles are expanded to relatively high densities, only a small amount of pentane will be needed for expansion. Consequently, the produced high-density particles will still contain about 4.3 to 5.5% by weight of pentane.
PL 199 952 B1
U.S. Patent No. 5,229,429 discloses expandable styrene polymers which contain a styrene polymer and at least one carbon dioxide absorber, mixed or copolymerized with the polymer, and a blowing agent or blowing agent mixture. The foaming agent or blowing agent mixture comprises 10-100 wt% carbon dioxide and 0-90 wt% of at least one additional foaming agent. In contrast, expandable styrene polymers have only been disclosed to be used in low density applications, i.e. expanded to a density of 4 kg / m3.<sup>3</sup> up to 100 kg / m<sup>3</sup>.
The object of the present invention is to provide particles which do not have the drawbacks mentioned above. In particular, it is an object of the invention to produce polyvinylarene particles that can be expanded without environmental safety and foam production problems.
The porous polyvinylarene particles produced from non-foamed polystyrene particles according to the invention are characterized in that these porous polyvinylarene particles have a pore structure that allows the particles to be impregnated with a harmless blowing agent and an apparent density of up to 600 to 200 kg / m3<sup>3</sup> and the porous particles contain 0.01 to 3 wt.%, based on the amount of polyvinylarene, nucleating agent, and 2.0 wt.% or less, based on the amount of polyvinylarene, volatile organic blowing agent, and the porous particles exhibit a volume increase of 1.5 to less than three times the volume of these unexpanded particles, the nucleating agent being selected from the group consisting of calcium carbonate, barium sulfate, calcium sulfate, talc, clay, magnesium silicate, amorphous silica particles, zeolites, diatomaceous earth, magnesium oxide, titanium oxide, mixtures of sodium bicarbonate with citric acid, organic compounds containing bromine, naphthalene compounds, polycyclic aromatic hydrocarbons, carbon black, coke, decolorizing carbon, graphite and diamond dust, paraffin , fatty acid derivatives, polyvinyl chloride particles, polypropylene particles, polyethylene particles, acrylonitrile / butadiene / styrene rubber particles, styrene-butadiene rubber particles, styrene / maleic anhydride copolymer particles, cellulose particles, modified starch particles, bis-alkyl sulfosuccinates, C8-C20-sorbitan carboxylates, C8-C20-alkyloxylene sorbitan sulfonates, polyethylene waxes with a weight average molecular weight of 500 to 5000 and mixtures thereof, and volatile organic blowing agents are selected from the group consisting of C2-C6 hydrocarbons, halogenated hydrocarbons, and mixtures thereof.
Preferably, the particles have an apparent density d0 530 to 250 kg / m3<sup>3</sup>.
Preferably, the particles contain less than 3.0 wt.%, Based on the amount of polyvinylarene, of water.
Preferably, the particles, exposed to saturated steam at a pressure above atmospheric pressure to a final temperature of 105 ° C for 30 seconds, expand to an apparent density that is at most three times lower than to.
Preferably, the particles have a pore structure having an average pore size of 5 to 100 µm.
Preferably, the polyvinylarene particles are polystyrene particles.
The method for producing porous polystyrene particles according to the invention is characterized in that expandable polystyrene particles containing a nucleating agent and from 0.5 to 4% by weight of C2-C6 organic blowing agent in relation to polystyrene are pre-expanded to an apparent density of 600 up to 200 kg / m<sup>3</sup> to form a pore structure in these porous polystyrene particles which allows the particles to be impregnated with a harmless blowing agent, and the porous polystyrene particles contain 2% by weight or less of C2-C6 organic blowing agent, based on the amount of polystyrene, the nucleating agent being selected from the group consisting of carbonate calcium, barium sulfate, calcium sulfate, talc, clay, magnesium silicate, amorphous silica particles, zeolites, diatomaceous earth, magnesium oxide, titanium oxide, mixtures of sodium bicarbonate with citric acid, organic compounds containing bromine, naphthalene compounds, polycyclic aromatic hydrocarbons, carbon black, coke, decolorizing carbon, graphite and diamond dust, paraffin, fatty acid derivatives, polyvinyl chloride particles, polypropylene particles, polyethylene particles, acrylonitrile / butadiene / styrene rubber particles, styrene-butadiene rubber particles, styrene / maleic anhydride copolymer particles, cellulose particles, modified starch particles, bis-alkyl sulfosuccinates, C8-C20-carboxylates of sorbitol, C8-C20-alkyloxylene sorbitan sulfonates, polyethylene waxes with a weight average molecular weight of 500 to 5000, and mixtures thereof.
Preferably, the expandable polystyrene particles are prepared by a suspension polymerization in which styrene is polymerized in an aqueous suspension in the presence of a nucleating agent and 0.1 to 1% by weight of a free radical initiator, wherein a C2-C6 organic blowing agent is added.
Before, during or after polymerization, in an amount of 0.5 to 4% by weight, based on the amount of styrene, to obtain expandable polystyrene particles.
Preferably, the pre-expansion of the polystyrene particles is carried out by exposing them to hot air.
Preferably, the hot air is at a temperature of 90 to 200 ° C.
The use of the particles defined above according to the invention is characterized in that the particles are used in the production of foamed particles and foam articles.
It is obvious that these particles eliminate all the problems presented above. Since the amount of volatile organic blowing agent is 2.0 wt% or less, most or all of the blowing agent is dissolved in the polymer matrix, and thus it does not evaporate so readily.
The porous polyvinylarene particles of the invention are typically prefoamed particles. This has the advantage that the particles already have a certain pore (cell) structure. Because pre-expansion is carried out to an apparent density in the range of 600 to 200 kg / m3<sup>3</sup>, the pores are relatively small and the increase in volume compared to the non-expanded particles is very small, so that the transportation costs do not increase significantly. The apparent density is suitably in the range from 530 to 250 kg / m3<sup>3</sup>. Typically this means that the volume of the pre-expanded particle can increase by from about 1.5 times to less than 3 times the volume of the original unfoamed particle. In this way, there is no increase in volume that would make the transport costs outweigh the benefits. Most suitable is an apparent density in the range of 450 to 350 kg / m3<sup>3</sup>.
Pores with an average size in the range of 5 to 100 µm, preferably 5 to 60, most preferably 10 to 40 µm are suitable. The mean pore size is measured by cutting the particles in half and imaging the samples with a JEOL JSM T220A Scanning Electron Microscope with the following parameters: beam energy 10 keV, continuous working distance 8-38 mm, secondary electron imaging, resolution 5 nm (JEOL is a trademark of ). The presence of a certain pore structure in the particles according to the invention allows them to be impregnated with a harmless foaming agent.
The particles of the invention contain a nucleating agent which is a compound that promotes cell formation. The nucleating agents exist as a separate phase in the polystyrene / blowing agent / nucleating agent system at the glass transition temperature of the polystyrene / blowing agent mixture. They are preferably homogeneously distributed throughout the polyvinylarene matrix. Preferably, the nucleating agent has an electron microscopy mean particle size of from 100 nm to 10 µm, more preferably from 120 nm to 5 µm, most preferably from 140 nm to 1 µm. Nucleating agents are suitably used in an amount of 0.01 to 3% by weight, based on vinylarene, preferably in an amount of 0.05 to 2% by weight.
Examples of nucleating agents include finely dispersed inorganic compounds, organic compounds and polymer particles. Examples are carbonates such as calcium carbonate, sulfates such as barium sulfate and calcium sulfate, silicate compounds such as talc, clay, magnesium silicate, amorphous silica particles, zeolites, diatomaceous earth, oxides such as magnesium oxide and titanium oxide, sodium bicarbonate mixtures with citric acid, organic compounds containing bromine, naphthalene compounds, polycyclic aromatic hydrocarbons, soot, coke, decolorizing carbon, graphite and diamond dust, paraffin and fatty acid derivatives such as stearate and palmitate. Examples of suitable polymer particles include polyvinyl chloride, polypropylene, polyethylene, acrylonitrile / butadiene / styrene rubber, styrene-butadiene rubber, styrene / maleic anhydride copolymer, and cellulose. Further examples include polar polymers such as those described e.g. in WO 98/01501 which include e.g. starch and starch modified by esterification or etherification, emulsifiers such as those described e.g. in WO 98/01488 and WO 98/01489, which include bis alkyl sulfosuccinates, sorbitan C8-C20 carboxylates and C8-C20 alkyloxylene sulfonates. Particularly suitable as nucleating agents are polyethylene waxes with a weight average molecular weight of 500 to 5000, which are usually finely dispersed in the polymer matrix in an amount of 0.01-1.0% by weight based on the amount of vinylarene, preferably from 0.1 to 0, 5% by weight.
The amount of volatile organic blowing agent in the particle according to the invention is 2.0% by weight or less with respect to the polyvinylarene. Preferably, the amount of this agent is less than 1.5% by weight, more preferably as low as possible, e.g. less than 1.0% by weight. Volatile organic blowing agents are well known in the art and are typically C2-C6 aliphatic organic blowing agents such as propane, butane, pentane, hexane, cyclohexane or halogenated organic blowing agents. Most preferably, the particles do not contain organic
A foaming agent. Preferably, the polymer particles according to the invention contain less than 3.0 wt.% Water, based on the amount of polyvinylarene. This amount of water is precisely the maximum amount that remains after conventional suspension polymerization. Contrary to what is disclosed in GB 1 106 145 and WO 98/1489, no special measures need to be taken to keep more water in the particles. Preferably, the amount of water is less than 1.5 wt%, more preferably less than 0.5 wt%.
The porous particles of the invention can be made in several ways.
One possible method is to pre-expand conventional expandable polyvinylarene particles to an apparent density in the range of 600-200 kg / m3<sup>3</sup> and subjecting them to reduced pressure and / or heating conditions to evaporate the (relatively large) excess of blowing agent. However, it is desirable to pre-expand expandable polyvinylarene particles containing less blowing agent. Thus, preferably, the porous particles of the invention are prepared by a process in which expandable polyvinylarene particles containing a nucleating agent and from 0.5 to 4.0% by weight of C2-C6 organic blowing agent, based on polyvinylarene, are pre-expanded to an apparent density. 600 to 200 kg / m<sup>3</sup>. More preferably, the porous particles of the invention are prepared by a process in which expandable polyvinylarene particles containing from 0.5 to 2.0% by weight of volatile organic blowing agent, based on polyvinylarene, are pre-expanded to an apparent density of 600 to 200 kg / m<sup>3</sup>.
Alternatively, it has been found that porous polymer particles can also be produced by foaming particles prepared by the process described in the parallel published Polish patent application P 346 694. The compact polyvinylarene particles are impregnated with an inorganic gas containing N2 and / or O2 at a temperature below 95 ° C and under 100 to 2000 kPa gauge pressure to give expandable polyvinylarene particles.
Another possibility is to produce the porous particle according to the invention "in situ". For this purpose, styrene is bulk polymerized in the extruder in the presence of a blowing agent. As the hot polymer melt leaves the extruder, a foaming agent is released which foams to a density of 600-200 kg / m<sup>3</sup>. Subsequently, the slightly foamed polymer strands are cut into the particles according to the invention. In this technique, it is preferred to use carbon dioxide as a blowing agent or to use so-called chemical blowing agents. Chemical blowing agents are compounds which release gaseous components when heated. Chemical blowing agents are usually solids and are used in particular in bulk polymerization techniques.
An example is carbon dioxide or nitrogen releasing solids such as azodicarbonamide.
The expandable polyvinylarene particles from which the porous particles of the invention are prepared can be produced by a variety of methods. These methods include bulk polymerization, solution polymerization and suspension polymerization. The polymerization reaction itself can be initiated thermally and can be carried out as free radical or anionic polymerization. The foaming agent may be added before, during or after the polymerization. In addition to hydrocarbons, e.g. C 2 -C 6 hydrocarbons or halogenated hydrocarbons and water, other blowing agents can also be used. Examples are inorganic blowing agents such as carbon dioxide or, as in the parallel published Polish application P 346 694, inorganic gases containing N2 and / or O2. Chemical blowing agents are further examples.
In bulk techniques, polymerization is carried out in a conventional manner and produces small particles that are impregnated with a blowing agent. In the present invention, such impregnation is preferably carried out with 0.5 to 4% by weight of C2-C6 organic blowing agent, more preferably 0.5 to 2.5% by weight of C2-C6 organic blowing agent. The nucleating agent may be added before or during the bulk polymerization.
Preferably, the expandable particles are prepared by a suspension polymerization process in which the vinylarene is polymerized in an aqueous suspension in the presence of a nucleating agent and from 0.1 to 1% by weight of a free radical initiator, wherein a C2-C6 organic blowing agent is added before, during or after polymerization, the amount of foaming agent being in the range of 0.5 to 4% by weight, based on the amount of vinylarene, to obtain expandable polyvinylarene particles.
The nucleating agent may be added before or during polymerization, preferably prior to polymerization. More preferably, the expandable particles are produced by a process in which the amount of the foaming agent is in the range of 0.5 to 2.5% by weight based on the amount of vinylarene. Many methods and initiators for suspension polymerization are known, e.g. from patents
PL 199 952 B1
US 2 656 334 and 3 817 965 and from the application EP 488 040. The initiators mentioned therein are also suitable for the production of particles according to the invention. Organic peroxy compounds such as peroxides, percarbonates and peresters are particularly suitable. Typical examples of these peroxy compounds are C6-C20 acyl peroxides such as decanoyl peroxides, benzoyl peroxide, octanoyl peroxide, stearyl peroxide, peresters such as t-butyl perbenzoate, t-butyl peracetate, t-butyl peroxide, dihydroxy peroxides, as containing C3-C10 hydrocarbyl residues, including diisopropylbenzene hydroperoxide, di-t-butyl peroxide, t-butyl peroxy (2-ethylhexyl) carbonate, dicumyl peroxide, or combinations thereof. Initiators other than peroxy compounds, e.g. α, α'-azo-bis-isobutyronitrile, can also be used.
The suspension polymerization is carried out in the presence of suspension stabilizers. Suitable suspension stabilizers are well known in the art and include polyvinyl alcohol, gelatin, agar, polyvinylpyrrolidone, polyacrylamide, inorganic stabilizers such as alumina, bentonite, magnesium silicate, or phosphates such as tricalcium phosphate and / or disodium hydrogen phosphate, optionally in combination with any of the following. the stabilizing compounds mentioned earlier. The amount of the stabilizer may suitably range from 0.1 to 0.9% by weight based on the weight of the aqueous phase.
The suspension polymerization is carried out in two temperature steps: the first in the range from 85 to 110 ° C and the second from 115 to 140 ° C.
The expandable polyvinylarene particles have an average size in the range of 0.2-3.0 mm. In order to pre-expand them, they are placed at the temperature at which the polyvinylarene plasticizes and the foaming agent evaporates. This results in little pre-expansion of the expandable polyvinylarene particles to the particles of the present invention. Such pre-expansion can be carried out in several ways. Suitable well known methods include the use of an oil, infrared or microwave bath or steam bath. Steam at a temperature of 100 to 168 ° C at a gauge pressure of 0 to 600 kPa gauge may be used, depending on the presence of additives and / or other polymers in the foaming polyvinylarene particles. In the case of polystyrene, it is preferable to use saturated steam with a temperature of 100-125 ° C and pressures of 0 to 230 kPa Gauge. The expandable particles can also be pre-expanded by treating them with warm water. This method is advantageous. In this embodiment, the suitable water temperature is 60 to 100 ° C and the exposure time is 5 to 120 minutes. The most preferred pre-expansion method in the present invention is to use hot air at a temperature from 90-200 ° C, preferably from 95-160 ° C and most preferably from 100-140 ° C. The exposure time is preferably up to 3 hours.
The vinylarene contained in the porous polymer particles according to the invention preferably consists mainly of styrene. The polyvinylarene may contain up to 10 mole% of another vinyl group containing monomer such as acrylonitrile, acrylic or methacrylic acid or esters thereof, substituted styrene such as chlorostyrene or α-methylstyrene or divinylbenzene. However, it is preferred that the vinylarene in the polyvinylarene comprises more than 99 mole% of styrene. More preferably the polyvinylarene is polystyrene.
It may be advantageous to polymerize the vinylarene in the presence of other polymers such as poly-phenylene oxide. These other polymers may be added before or during the polymerization reaction, or may be prepared in situ prior to initiating the polymerization of the vinylarene. Suitable poly-phenylene oxides are described in EP 350 137, EP 403 023 and EP 391 499. The poly-phenylene oxide is preferably present in an amount of 1-30% by weight based on the amount of vinylarene and can improve the stiffness of the polyvinylarene.
The expandable and / or porous polyvinylarene particles may contain various conventional additives. Such additives include chain transfer agents and crosslinkers. Suitable examples of chain transfer agents are C2-15 alkyl mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, t-butyl mercaptan and n-butyl mercaptan. Other agents are pentaphenylethane and α-methylstyrene dimer. Examples of crosslinkers are butadiene and divinylbenzene.
The expandable and / or pre-expanded particles may also contain antistatic additives, flame retardants such as hexabromocyclododecane, dyes, fillers, stabilizers, plasticizers such as white oil and lubricants. The particles are suitably coated with a coating composition comprising silicones, silicates, metal or glycerol carboxylates. Suitable carboxylates include glycerol mono-, di-, and tristearate, zinc stearate, and mixtures thereof. Examples of such compositions are disclosed in GB 1 409 285. Citrate or palmitate may also be used in place of the stearate. The coating compositions are applied to the particles by dry coating in a spiral mixer or by applying a slurry or solution in a evaporative liquid.
PL 199 952 B1
Unlike conventional high density polyvinylarene particles, the particles of the present invention are practically non-foaming. This means that when subjected to conventional foaming conditions, i.e. exposed to saturated steam at a pressure above atmospheric pressure until a final temperature of 105 ° C is reached for 30 seconds, the particles of the invention expand to an apparent density which is at most three times lower than up to.
Preferably, the particles according to the invention expand under these conditions to a density of at most two times lower than to.
In order to render the particles according to the invention sufficiently expandable, they are impregnated with a blowing agent. The present invention also relates to the use of the porous particles of the invention for the production of foamed particles and foam articles. Preferably, an inorganic gas is used as the foaming agent used for the impregnation. As already explained above, the volume of the pre-expanded particle may increase from about 1.5 to less than 3 times compared to the volume of the original unexpanded particle. This provides a pore size in the pre-expanded particle such that the voids in the particles can be saturated with a reasonable amount of inorganic gas.
"Inorganic" means that the impregnating gases according to the invention may contain at most 1% by volume, based on the volume of the gas, of organic compounds, and preferably at most 0.5% by volume. Most preferably, the inorganic gases contain no organic compounds.
An example of a suitable inorganic gas is carbon dioxide. However, carbon dioxide acts on the polyvinylarene matrix. Likewise, many commercial blowing agents dissolve to some extent in the polymer matrix. This means that in some applications they will have to be removed with difficulty due to potential negative effects, e.g. in the field of safety, health or toxicology. Carbon dioxide, also known as greenhouse gas, is therefore not beneficial. Inorganic gases that do not have this negative effect and that exhibit less interaction with the polymer matrix are preferred. Examples of such gases are N2- and / or O2-containing inorganic gases, helium, neon and argon. More preferably, the inorganic gas used for the impregnation is selected from inorganic gases containing N2 and / or O2. These gases contain more than 90 vol% based on the volume of gas, nitrogen and / or oxygen, more suitably more than 95 vol%. Most preferably, the gas is nitrogen or air. These gases not only hardly interact with the polymer matrix, but are also effective and cheap and have no negative impact on the environment or health.
The impregnation can be done in many ways. However, it is preferred to impregnate the particles of the invention with an inorganic gas by exposure to the gas at a temperature ranging from 0 to 95 ° C. In this way, the voids in the particles are filled with gas without heating the polyvinylarene, which deforms them. Such deformation could have a detrimental effect on the structure and properties of the voids and thus negatively affect the expandability of the resulting impregnated particles. In addition, the low temperature ensures that the particles are free flowing and do not stick to each other, which would be the case if impregnation was carried out at higher temperatures. A preferred temperature range for the impregnation process is from 0 to 50 ° C, more preferably from 10 to 30 ° C. Room temperature is most preferred.
A saturation is suitable such that a pressure of 100 to 1500 kPa gauge is achieved in the pores of the porous particles. Preferred pressures in the pores are in the range of 200-1000 kPa Gauge, more preferably 300-800 kPa Gauge. Pressures below 100 kPa gauge would mean that the voids would only be filled with gas, e.g. nitrogen or air, at about atmospheric pressure. Such a change would lead to insufficient foaming, if any foaming occurred at all. Pressures greater than 1500 kPa gauge are also possible, but are not economically and for safety reasons. The applied external pressures needed to establish the desired pressure in the pores are preferably 100 to 2000 kPa. Although higher external pressures could be used, this would require better equipped pressure vessels and make sampling more difficult. Preferably, a maximum external pressure of 1500 kPa is used. Accordingly, the external pressure used is the same as the pressure desired in the pores of the porous particles.
Upon impregnation with a blowing agent, the resulting saturated particles suitably expand to an apparent density of at least three times lower than that of. Preferably the saturated particles are expanded to a density at least 5 times lower than that of. Although expansion may be carried out to any desired apparent density, it is practically carried out to an apparent density which is up to 20 times more preferably.
PL 199 952 B1 not up to 40 times lower than up to. The foaming can be carried out according to the same methods as described for pre-foaming. The use of steam is advantageous. The foamed particles are combined together in a mold and foam products are produced.
The invention is illustrated by the following non-limiting examples.
All apparent densities were measured according to the following method:
A cylindrical mug with a capacity of 1000 cm<sup>3</sup> ± 2 cm<sup>3</sup>66 mm ID and 293 mm high were weighed and rounded to 0.1 g (atmospheric pressure, room temperature). The cup was then filled with polyvinylarene particles. The sides of the cup were tapped three times with a flat metal scraper and excess material was collected from the top of the cup without shaking it. The material in the cup was weighed by rounding the result to 0.1 g and the weight of 1 cm was calculated in grams<sup>3</sup> polyvinylarene particles and converted to kg / m3<sup>3</sup>.
All pentane contents were measured by gas chromatography using n-hexane as an internal standard.
The water content was measured by the Karl Fischer method.
Example 1
Manufacture of EPS particles
The polystyrene particles were prepared by the suspension polymerization process. For this, 4000 g (4 l) demineralized water, 3680 g (4 l) styrene, conventional suspension stabilizers, 0.25% by weight polyethylene wax based on the weight of styrene were mixed at a speed of 475 rpm and 0.25% by weight. by weight of white oil. The polymerization was started by increasing the temperature to
86 ° C and by adding peroxide initiators (0.65 wt%). In addition, 0.05% by weight of α-methylstyrene dimer was added. After about 6 hours, 81 g of pentane (mixture of 75 wt% n-pentane and 25 wt% isopentane) was added and the temperature was raised to about 120 ° C and held at this level for 2 hours. After the end of the polymerization, the reaction mixture was cooled.
The polystyrene particles produced contained 2.1% by weight of pentane by weight of polystyrene, 0.25% by weight of polyethylene wax by weight of polystyrene, and had a size in the range of 0.4-0.7 mm.
Pre-foaming
The polystyrene particles were placed in a water bath at 100 ° C for 900 seconds. They were then dried at 60 ° C for 15 minutes. The produced pre-expanded particles had an average density of up to 500 kg / m3<sup>3</sup>, pentane content 1.77 wt.% with respect to the weight of polystyrene and water content 0.2 wt.%.
Foaming
The pre-expanded polystyrene particles were placed in a KURTZ KV450 batch steam expander using saturated steam at a pressure above atmospheric pressure to a final temperature of 105 ° C (KURTZ is a trademark). The foaming time was 30 seconds. The particles were expanded to an average density of d 362 kg / m3<sup>3</sup>. The calculated do / d ratio was 1.4.
Example 2
The procedure of Example 1 was repeated except that the polystyrene particles were pre-expanded in the KURTZ KV450 batch pre-expander using a vapor pressure of 80 kPa at 117 ° C for 15 seconds.
The resulting pre-expanded particles had an average density do of 536 g / l, a pentane content of 1.92% by weight, based on the weight of polystyrene, and a water content of 0.1% by weight.
After placing the pre-expanded particles in the KURTZ KV450 series steam expander, they expanded to an average density of d 427 kg / m3<sup>3</sup>. The calculated ratio do / d was 1.3.
Example 3
The procedure of Example 1 was repeated except that the polystyrene particles were pre-expanded in the KURTZ KV450 batch pre-expander using a vapor pressure of 80 kPa at 117 ° C for 45 seconds.
The produced pre-expanded particles had an average density of up to 256 kg / m3<sup>3</sup>, pentane content 1.77 wt.% with respect to the weight of polystyrene and water content 0.1 wt.%.
After placing the pre-expanded particles in the KURTZ KV450 series steam expander, they expanded to an average density of d 124 kg / m3<sup>3</sup>. The calculated ratio do / d was 2.1.
PL 199 952 B1
Example 4
The procedure of Example 1 was repeated except that 62 g of pentane were used in the slurry. The polystyrene particles produced contained 1.6% by weight of pentane and had a size in the range of 0.7-0.9 mm. The amount of polyethylene wax was 0.25% by weight.
Then, the polystyrene particles were pre-expanded in a KURTZ KV450 steam pre-expander, under an overpressure of 40 kPa and a temperature of 109 ° C for 20 seconds. The produced pre-expanded particles had an average density up to 350 kg / m3<sup>3</sup>, a pentane content of 1.1% by weight, based on the weight of polystyrene, and a water content of 0.1% by weight.
Then, the pre-expanded particles were placed in a KURTZ KV450 batch steam expander for 30 seconds using saturated steam at a pressure above atmospheric pressure to obtain a final temperature of 115 ° C instead of 105 ° C. The particles were expanded to an average density of d 125 kg / m3<sup>3</sup>. The calculated ratio do / d was 2.8.
Example 5
Manufacture of EPS particles
Polystyrene particles were produced by a suspension polymerization process. For this purpose, 67.7 g (67.6 l) of demineralized water, 79.34 kg (86.4 l) of styrene, conventional suspension stabilizers, 0.5% by weight based on the weight of styrene were mixed at a speed of 170 rpm, polyethylene wax. Polymerization was started by increasing the temperature to 86 ° C and by adding peroxide initiators (0.57 wt%). After about 4.5 hours, 2.5 L of pentane (mixture of 75 wt% n-pentane and 25 wt% isopentane) was added and the temperature was raised to about 120 ° C and held at this level for 2 hours. After the end of the polymerization, the reaction mixture was cooled.
The produced polystyrene particles contained 1.66% by weight of pentane, based on the weight of polystyrene, and had a size in the range of 0.4-0.7 mm. The amount of polyethylene wax was 0.5% by weight with respect to the weight of the polystyrene.
Pre-foaming
The polystyrene particles were pre-expanded by exposing them to hot air at 97-100 ° C for 2700 seconds. The produced pre-expanded particles had an average density up to 428 kg / m3<sup>3</sup>, pentane content 1.29 wt%, based on the weight of polystyrene, and water content 0.2 wt%.
Foaming
The pre-expanded polystyrene particles were placed in a KURTZ KV450 batch steam expander using saturated steam at a pressure above atmospheric pressure to a final temperature of 105 ° C (KURTZ is a trademark). The foaming time was 30 seconds. The particles were expanded to an average density of 316 kg / m3<sup>3</sup>. The calculated do / d ratio was 1.4.
Example 6
Manufacture of EPS particles
Polystyrene particles were produced by bulk polymerization followed by suspension polymerization. For this purpose, 69 l of styrene, 354 g of maleic anhydride and 1000 g of starch were mixed at 175 rpm. Polymerization was started by increasing the temperature to 120 ° C and by adding peroxide initiators (0.025% by weight). After 90 minutes, the mixture was cooled to 60 ° C and transferred to another vessel where 91 kg (91 L) of demineralized water, the resultant bulk polymerization mixture and conventional slurry stabilizers were mixed with a stirring speed of 175 rpm. Polymerization was started by increasing the temperature to 86 ° C and by adding peroxide initiators (0.30 wt%). After about 5 hours, the temperature was raised to about 120 ° C and held for 1.5 hours. After the end of the polymerization, the reaction mixture was cooled.
The polystyrene particles produced contained 2.6% by weight of water, based on the weight of polystyrene, and had a size in the range of 0.9-1.6 mm.
Pre-foaming
The polystyrene particles were pre-expanded by subjecting them to hot air at 127 ° C for 100 seconds. The produced pre-expanded particles had an average density of up to 330 kg / m3<sup>3</sup>.
Foaming
The pre-expanded polystyrene particles were placed in a KURTZ KV450 series steam expander using saturated steam at a pressure above atmospheric pressure to obtain
With a final temperature of 117 ° C. The foaming time was 30 seconds. The particles were expanded to an average density of 298 kg / m3<sup>3</sup>. The calculated ratio do / d was 1.1.
Comparative example
The expandable polystyrene particles were prepared as in Example 1, except that 267 g of pentane was used instead of 81 g. The polystyrene particles produced contained 6.2% by weight of pentane, 0.25% by weight of polyethylene wax, and had a size in the range of 0.4- 0.7 mm.
Then, the polystyrene particles were pre-expanded by placing them in a water bath at 70 ° C for 600 seconds. The produced pre-expanded particles had an average density of up to 520 kg / m3<sup>3</sup>, pentane content 5.9% with respect to the amount of vinylarene and the water content 0.15% by weight.
After placing in the KURTZ KV450 series steam expander under the conditions according to example 1, the particles expanded to an average density of 14.9 kg / m3.<sup>3</sup>. The calculated do / d ratio was 34.9.
Contents4
22 members in 14 offices
Priority claims7
| Document | Office | Kind | Date |
|---|---|---|---|
| 98203099 | European Patent Office (EPO) | A | |
| 98203099 | European Patent Office (EPO) | A | |
| 9906995 | European Patent Office (EPO) | W | |
| 9906995 | European Patent Office (EPO) | W | |
| 982030991 | – | – | – |
| EP19980203099 | – | – | – |
| WO1999EP06995 | – | – | – |
Members22
| Document | Office | Kind | |
|---|---|---|---|
| EP0987293A1 | European Patent Office (EPO) | A1 | |
| CA2341273A1 | Canada | A1 | |
| WO0015703A1 | World Intellectual Property Organization (WIPO) | A1 | |
| AU6194299A | Australia | A | |
| NO20011321D0 | Norway | D0 | |
| NO20011321L | Norway | L | |
| BR9913763A | Brazil | A | |
| EP1114090A1 | European Patent Office (EPO) | A1 | |
| KR20010073161A | Republic of Korea | A | |
| CN1318080A | China | A | |
| HUP0103666A2 | Hungary | A2 | |
| PL346696A1 | Poland | A1 | |
| HUP0103666A3 | Hungary | A3 | |
| JP2002524638A | Japan | A | |
| US6538042B1 | United States of America | B1 | |
| AU761299B2 | Australia | B2 | |
| CN1111559C | China | C | |
| TWI224122B | Taiwan Province of China | B | |
| MY121090A | Malaysia | A | |
| KR100675471B1 | Republic of Korea | B1 | |
| PL199952B1This record | Poland | B1 | |
| CA2341273C | Canada | C |
1 legal event, as the office reported them to INPADOC
Events
| Event | Code | |
|---|---|---|
| Decisions on the lapse of the protection rightsLapsedLAPS | LAPS |
Numbers
- Publication
- 199952
- Publication, DOCDB
- 199952
- Publication, EPODOC
- PL199952B
- Application
- 346696
- Application, DOCDB
- 34669699
- Application, EPODOC
- PL19990346696
Titles2
- English
- POROUS POLYMER PARTICLES
- Polish
- Porowate cząstki poliwinyloarenów, ich zastosowanie i sposób wytwarzania porowatych cząstek polistyrenowych
Classification
- CPC, 4
- C08J9/18
- C08J9/22
- C08J2325/04
- Y10S264/09
- IPC, 4
- C08J9 16
- C08J9 18
- C08J9 22
- C08L25 06