JP6309007B2 - Particulate foamable polymer, production method thereof, and application thereof - Google Patents

Description

  The present invention relates to a particulate foamable polymer that can be processed into a flame retardant foam having a microporous structure and low density, including a carbon-based material that improves heat insulation in order to improve heat insulation. The present invention further relates to a method for producing a particulate foamable polymer and a foam material obtained by the method.

  Expandable polymer materials at concentrations ranging from 80 to 99%, 3.0 to 12%, and 0.05 to 5.0%, respectively, as a percentage based on dry weight, 1,1 as the only desirable blowing agent A composition for producing thermoplastic polymer foams comprising 1,2,2-tetrafluoroethane and nanographite is known from WO 2008/119059. The nanographite used has a thickness of at least one dimension of less than 100 nm and is preferably a multilayer nanographite contained in a carrier, ie a polyethylene-methyl acrylate copolymer. The addition of nanographite is claimed to improve the thermal properties, mechanical properties, and flame retardancy of the final foam product.

  WO 2007/058736 relates to a thermally stable brominated copolymer. The copolymer to be polymerized here includes a butadiene portion and an aromatic vinyl portion. Such a copolymer is added to the polystyrene in an amount that inhibits combustion, and finally a mixture having a bromine content in the range of 0.1 to 25% by weight of the mixture is obtained.

  US 2002/0117769 relates to expanded porous polymer particles to which additives such as carbon black, titanium oxide, aluminum and graphite can be added to reduce thermal conductivity.

  US Patent Application Publication No. 2012/0123007 relates to a styrene polymer composition to which a brominated flame retardant has been added.

  Expandable polystyrene (EPS) containing activated carbon as a material for improving heat insulation in polystyrene particles is known from European Patent No. 1486530 (corresponding to NL No. 1023638) by the present applicant. Suitable activated carbon has a particle size of 12 μm or less. The foam obtained by using such a material that improves heat insulation meets the fire resistance requirement according to the B2 test, that is, DIN 4102 part2.

  As means for improving heat insulation, expandable polystyrene (EPS) using activated carbon having a specific particle size distribution is known from WO 2010/041936 by the present applicant.

  A method for producing graphite-containing EPS in which 0.05 to 25% by weight of graphite is added to the styrene polymer is known from US Pat. No. 6,130,265.

  Expandable polystyrene is known from US Pat. No. 6,340,713 which contains 0.05-8% by weight of homogeneously dispersed graphite particles with a styrene polymer having an average particle size of 1-50 μm.

  A method for improving the heat insulating performance of EPS is also known from WO 00/43442. In this method, the styrene polymer is melted in an extruder, mixed with at least a blowing agent and up to 6% by weight aluminum particles, mainly in the form of plates, extruded together, and the extrudate is cooled and reduced to particles. Is done. Such polymers include at least aluminum in the form of particles incorporated as a uniformly dispersed material that reflects infrared radiation to improve thermal insulation properties. The aluminum particles have a plate shape with a size of 1 to 15 μm.

  The starting materials used for the production of expandable polystyrene (EPS) can be obtained not only by the extrusion process known from the aforementioned international patent application, but also by suspension polymerization. The EPS granules thus obtained are widely used as starting materials in the packaging and construction industries. A method for further processing is to pre-foam the foam by evaporating the foaming agent, usually pentane, contained in the EPS granule by evaporating a certain amount of steam through the EPS granule layer in an expansion vessel. Includes processing. After a storage period of about 4 to 48 hours, also called curing, the granules so prefoamed are introduced into the mold and further expanded under the influence of steam. The mold used has a small opening that allows the blowing agent still present to escape during expansion while the granules melt into the desired shape. The size of this shape is not limited in principle, and it is possible to obtain blocks for the construction industry and packaging materials for the food and non-food industries. The method described above is essentially different from the method known from WO 2008/119059 for a foam that is continuously foamed in a single step process in a continuous extruder.

  In many cases, flame retardants are added to foam products. Such foams are further processed into products and objects, but their flame retardant performance needs to meet the requirements stipulated by national authorities. Such flame retardants are presumed to have unacceptable chemical effects on humans and the environment. Therefore, certain flame retardants are abolished.

  One object of the present invention is to provide a particulate foam which, after further processing, results in a foam having a sufficiently low thermal conductivity, which is practically desired, suitable for use for the desired thermal insulation properties. Is to provide a functional polymer granule.

  Another aspect of the present invention provides a process for producing expandable polymer granules capable of converting a styrene polymer into a material having high thermal insulation performance after foaming and molding in the presence of one or more additional components. That is.

  Another aspect of the present invention is to provide a process for producing expandable polymer granules using flame retardants that are safe for humans and animals and meet current safety standards in the construction industry and exhibit low biotoxicity. is there.

  The present invention referred to in the preamble is characterized in that the polymer particles include carbon having a particle size of less than 1 μm as a material for improving thermal insulation performance, and brominated SBS (styrene-butadiene-styrene) as a flame retardant. To do.

  One or more aspects of the present invention are satisfied by using such types of carbon as a material to improve thermal insulation performance. The above-mentioned flame retardants are considered as a means to meet current safety standards in the construction industry and have little impact on humans and the environment.

  A preferred value for the lower limit of the particle size is 0.1 μm. The present invention specifically excludes the use of carbon black as a carbon source.

  It is particularly desirable that the D50 particle size is 1 μm or less, more specifically 0.8 μm or less.

  The D90 and D50 values are understood to be the 90th and 50th percentiles, respectively, such that the overall 90% and 50% granularity, respectively, is less than this value. D10 (10% of the total is smaller than this particle size), D50 (half of the total is smaller than this particle size), and D90 (90% of the total is smaller than this particle size) are manufactured by Malvern. Instruments can be easily inferred from the cumulative distribution curve obtained by using the products Mastersizer and Lazersizer, these three values (D10, D50 and D90) are the particle size of the powder Can be used to characterize the distribution. In particular, (D90-D10) / D50 (also referred to as particle size distribution) provides a good indicator for the spread of particle size contained in the powder.

  In other words, the 10 percent point is the particle size at which 10% of the particles have a particle size below this value, and thus 90% of the particles have a particle size greater than this value.

  In other words, the 50 percent point is the particle size at which the particle size of 50% is less than or equal to this value, and thus the particle size of 50% is greater than this value. D50 is preferably 1.0 μm or less, and particularly preferably 0.8 μm or less.

  In other words, the 90 percent point is the particle size at which 90% of the particles have a particle size below this value, and thus 10% of the particle size is greater than this value.

  A block copolymer of polystyrene and brominated polybutadiene is preferably used as brominated SBS (styrene-butadiene-styrene) in the particulate foamable polymer of the present invention.

  The weight percentage of bromine is preferably in the range of 60-70% by weight, based on brominated SBS (styrene-butadiene-styrene). A preferred range of 30-50% by weight based on brominated SBS (styrene-butadiene-styrene) is defined as the weight percent of styrene.

  In a special embodiment, the molecular weight of brominated SBS (styrene-butadiene-styrene) is preferably in the range of 60000-150,000.

  The amount of brominated SBS (styrene-butadiene-styrene) is preferably in the range of 0.7 to 2.2% by weight, based on the total weight of the particulate foamable polymer.

  In a special embodiment, the amount of hexabromocyclododecane (HBCD) is less than 1.0% by weight, in particular less than 0.6% by weight, calculated on the total weight of the particulate foamable polymer. More specifically, it is less than 0.2% by weight, preferably less than 0.05% by weight.

  The above values have been found to be particularly suitable in terms of polymer compatibility, required flame retardant properties, biotoxicity, thermal stability, and sustainability.

  The polymer used in the present invention is selected from the group comprising polystyrene, expanded polypropylene (EPP), expanded porous polyethylene (EPE), polyphenylene oxide (PPO), polypropylene oxide, and polylactic acid, or combinations thereof.

  Polylactic acid (PLA) is a collective name for lactic acid monomer-based polymers, and its structure varies from completely amorphous to semi-crystalline or crystalline depending on its composition. Polylactic acid can be produced, for example, from dairy products, starch, flour, and corn. Lactic acid is a monomer constituting polylactic acid, and there are two stereoisomers of L-lactic acid and D-lactic acid in this monomer. Therefore, polylactic acid includes a certain ratio of L-lactic acid monomer and a certain ratio of D-lactic acid monomer. The characteristics of polylactic acid are determined by the ratio of L-lactic acid monomer and D-lactic acid monomer in polylactic acid. In this context, the terms “D value” and “D content” (percentage of D-lactic acid monomer) are also used. The L: D ratio of currently commercially available polylactic acid is 100: 0 to 75:25, in other words, the D content is 0 to 25% or 0 to 0.25.

  Examples of further processing of PLA granules are as follows. PLA granules are impregnated with, for example, 6-8% carbon dioxide and then foamed, for example with a pressure of 20 bar. Thereafter, PLA is foamed again, for example, impregnated with 6% carbon dioxide, and molded in steam at a pressure of 0.2 to 0.5 bar in a mold. Similar to the method described above in connection with EPS granules, a molded product is obtained in this way.

  PLA granules are manufactured using an extruder die plate. For this purpose, solid PLA is introduced into the extruder and melted. Subsequently, the molten PLA is pressed by a mold such as a so-called underwater granulator, and the PLA granules are cut by a die plate. It is also possible to feed the liquid PLA directly to the extruder in an in-line polymerization process, in which case it does not need to be melted first. A twin screw extruder is preferably used as the extruder. In an extruder, granulate polylactic acid or a mixture of polylactic acid and one or more other biodegradable polymers selectively having one or more chain extenders, nucleating agents, and lubricants. Can be processed. Such particulate polylactic acid is also described in the international application PCT / NL2008 / 000109 by the present inventors.

  After extrusion of polylactic acid, PLA granules are impregnated and a foaming agent is added to obtain foamable PLA (EPLA). Examples of blowing agents that can be used include carbon dioxide, MTBE, nitrogen, air, (iso) pentane, propane, butane, etc., or a combination of one or more thereof. The first method is to form polylactic acid into particles by, for example, extrusion, and then impregnate the particles with a foaming agent to make them foamable. In the second method, polylactic acid is mixed with a foaming agent and then molded directly into expandable particles, for example by extrusion.

  In particular, in order to obtain a specific heat insulation performance, the present inventors used graphene or expanded graphite, which is considered to be a single atomic thickness flat layer of sp2 bonded carbon atoms arranged in a honeycomb-like flat crystal lattice, We believe that it can be used in smaller quantities than other carbon sources such as conventional state-of-the-art heat insulation performance improvers, especially graphite and activated carbon. Additional tests have shown that the material referred to herein as “graphene” may be considered expanded graphite having a particle size of 0.1-0.8 μm. Therefore, in the present specification, “graphene” is understood as expanded graphite having a particle size of 0.1 to 0.8 μm. Such a reduction in the amount of heat insulation performance improver has a positive effect on the final color of the EPS, which is originally white. With the aforementioned additives, the originally white EPS “discolors” somewhat to gray.

  Thus, the present invention focuses on the use of a special carbon source, in particular expanded graphite, combined with a special flame retardant, in order to meet both thermal insulation requirements and fire resistance requirements. Expanded graphite can exhibit a noticeable effect in a small amount. This surprising result is believed to be due to the special geometric design of expanded graphite. The above combinations of special carbon sources and specific flame retardants should be considered the essence of the present invention.

  As used herein, the term “expanded graphite” should not be confused with the term “nanographite” known from WO 2008/119059 as far as dimensions and dimensional structures are concerned. .

  In a particular embodiment, it is particularly desirable to use expanded graphite with an aspect ratio of 10: 1 or higher, in particular 100: 1 or higher. Such a layered structure has a particularly good influence on the improvement of the heat insulation performance.

  It is particularly desirable for the carbon content to be 1-15% by weight, based on the polymer, preferably 2-8% by weight, based on the polymer.

In certain embodiments, 1 selected from the group comprising graphite, carbon black, powdered aluminum, Al (OH) ₃ , Mg (OH) ₂ , and Al ₂ O ₃ , iron, zinc, copper, and alloys thereof. It will be apparent that the above heat insulation performance improver is desirably further present in the particulate foamable polymer.

  In the past, hexabromocyclododecane (HBCD) was used as a flame retardant to obtain a good flame retardant effect. The present invention pays particular attention to the use of alternatives to HBCD, resulting in a final product that is comparable to polymer products containing HBCD, particularly with respect to fire requirements. In particular, an object of the present invention is to minimize the amount of HBCD, and more specifically to reduce the amount of HBCD to zero.

  If the resulting product needs to meet strict fire protection requirements, it is selected from the group comprising dicumyl peroxide, brominated polymer compounds, especially polystyrene compounds, and 2,3-dimethyl-2,3-diphenylbutane. It is desirable to further replenish one or more flame retardants in the range of 1.0 to 8% by weight, based on the amount of polymer. It is also possible to add as an auxiliary a phosphorus compound selected from the group comprising polyphosphonates, diphenylphosphonates, bisphenol A-bis (diphenyl phosphate), resorcinol aromatic polyphosphate compounds, and combinations thereof.

  The expanded graphite referred to in this application is obtained by applying a mechanical shear force to the carbon source, in particular by subjecting such graphite to such treatment. An example of such a process is an extrusion method, in which graphite is subjected to a large shearing force in the extruder and converted into a flat carbon plate, particularly expanded graphite. The present inventors consider that the above-described flat carbon plate causes such a plate to reflect heat radiation by the mirror effect. For this reason, in order to realize the desired mirror effect, it is desirable that the carbon used has a somewhat flat dimension or geometric shape. In some embodiments, the carbon source may be added as a masterbatch or directly as a pretreated powder material to obtain the desired particle size as specified in the claims. .

  The present invention provides that after the polymer is fed to the extruder and mixed with at least a blowing agent, brominated SBS (styrene-butadiene-styrene), a carbon source, and one or more other auxiliaries mentioned in the subclaims, It also relates to a process for producing a particulate foamable polymer which is extruded, cooled and further reduced to particles.

In a special embodiment, the present invention provides that the monomer, brominated SBS (styrene-butadiene-styrene), blowing agent, thermal insulation improver, and one or more other auxiliaries mentioned in the subclaims are contained in the reactor. It also relates to a method for producing a particulate foamable polymer that is polymerized in step (b). In particular, the density of EPS as a suitable polymer is desirably 850 to 1050 kg / m ³ . A suitable blowing agent is (iso) pentane. As the blowing agent, it is desirable to exclude hydrocarbon compounds containing fluorine. Accordingly, the amount of hydrocarbon compound containing fluorine is minimized, preferably less than 2.0% by weight, in particular less than 1.0% by weight, more specifically less than 0.1% by weight, based on the amount of particulate foamable polymer. It is preferred to produce a particulate foamable polymer that is less than 5% by weight. By minimizing the above-mentioned fluorine-containing hydrocarbon compounds in the particulate foamable polymer, the final foam product is essentially free of fluorine-containing hydrocarbon compounds.

  The invention further relates to a polymer foam based on a particulate foamable polymer as described above, which is preferably used for insulation purposes, for example in the construction industry and also as a packaging material in the food and non-food industries. About.

Hereinafter, the present invention will be described with reference to some examples, but it should be noted that the present invention is not limited to these examples.
FIG. 1 shows the measurement results of various carbon sources. FIG. 2 is a graph showing the relationship between the density and λ value of various EPS materials.

The particle size distribution of various products was measured. The results are shown in the table below.

  It is particularly desirable that the D50 value is 1 μm or less, more specifically 0.8 μm or less.

    A number of mechanical properties of a number of commercially available products were measured and subjected to a combustion test. From the measurement results, it can be clearly inferred that the addition of graphene or expanded graphite has a positive effect on the thermal conductivity of the final EPS foam molded article.

The numbers in the table included below have the following meanings.
1 = HBCD as flame retardant
2 = no flame retardant 3 = resorcinol as flame retardant 4 = emerald 3000 as flame retardant (commercially available from Chemtura)
5 = FR122P as a flame retardant (commercially available from ICI)
6 = XP-7720 FR122P (commercially available from Albemarle) as a flame retardant

The columns in the table are, in order, raw material type, flame retardant weight%, dicumyl peroxide weight%, density (g / l), λ (W / mK), density (g / l), and compressive strength (kPa). ), Density (g / l), tensile strength at break (kPa), and combustion test DIN 4102-1 B2. In the table, “nt” indicates unmeasured and “Pass” indicates that it has passed.

  Simbra Technology's material EPS 710F, containing 5.5% pentane and having a particle size of 0.7-1.0 mm, 0.1% P1000 polyethylene (Baker Hughes), graphene masterbatch and Along with the graphene concentrate, it was melted in a twin screw extruder with a throughput of 125 kg / hr. This graphene masterbatch and graphene concentrate effectively introduce 4% graphene into the polystyrene. The temperature of the extruder is preferably 150 ° C. to 230 ° C. In this embodiment, 0.8% of additional pentane was added as a blowing agent. This mixture was passed through a cooling extruder having a temperature of 60 ° C. to 150 ° C. to produce a gray XPS plate.

The resulting foam had a density of 35 kg / m ³ . The insulation value of the foam was 31.1 mW / mK for the masterbatch and 30.9 mW / mK for the concentrate, and both products passed the combustion test DIN 4102 B2.

  FIG. 2 is a graph showing a large number of measured values, in which the horizontal axis represents density and the vertical axis represents λ value (W / mK). From this graph, 4% by weight of graphite (particle size is mainly more than 1 μm, especially 1 to 50 μm) than EPS to which a certain weight% of expanded graphite (particle size 0.1 to 0.8 μm) is added, It can be clearly inferred that a commercially available neopole of the same density gives a higher λ value.

Particle size measurement of expanded graphite 10 g of gray foamed EPS was dissolved in 28 ml of toluene, and the slurry was analyzed. The residue was further dispersed with ultrasonic waves by adding toluene, and analyzed with an ALV measuring device. The particle size was measured using a Malvern Zetasizer. If necessary, it was further diluted with toluene. The Zetasizer GMA is a so-called dynamic light scattering device having the following specifications. Correlator: ALV5000 / 60X0, external goniometer correlator: ALV-125, detector: ALV / SO SIPD single photon detector with static / dynamic enhancer ALV laser fiber optics (Cobalt Samba 300 DPSS Laser), wavelength: 532 nm, 300 mW output temperature control: static heat bath: Haake F8-C35. No special criteria were used. This apparatus measures the Brownian motion of particles, and the measured values were converted into particle sizes using the Einstein-Stokes equation under the assumption that the solvent was water and the particles were approximately spherical. The radius was measured.

  It was clear that the graphite reference material had a large particle size and was agglomerated, which could also be observed visually. The expanded graphite contained in EPS is much finer and is on average 3-5 times smaller than the particle size of graphite. There were some small particle agglomerations, but the agglomeration was not as pronounced as with graphite. The result is shown in the graph of FIG.

Claims (23)

A particulate foamable polymer that can be processed into a flame retardant foam having a microporous structure and low density, including a carbon-based heat insulation performance improver to improve heat insulation performance,
The particulate foamable polymer is a polylactic acid containing a carbon- based heat insulating performance improving material having a particle size of less than 1 μm as the heat insulating performance improving material and brominated SBS (styrene-butadiene-styrene) as a flame retardant. Particulate foamable polymer characterized. The particulate foamable polymer according to claim 1, wherein the carbon-based heat insulating performance improving material has a D50 particle size of 1 μm or less. The particulate foamable polymer according to claim 1 or 2, wherein the carbon-based heat insulating performance improving material has a D50 particle size of 0.8 µm or less. 2. An expanded graphite having a particle size of 0.1 to 0.8 μm, an aspect ratio of 10: 1 or more, and a flat carbon structure is used as a carbon- based heat insulation performance improving material. To 3. The particulate foamable polymer according to any one of items 1 to 3.   The particulate foamable polymer according to claim 4, wherein the expanded graphite has an aspect ratio of 100: 1 or more. 6. The particulate foamable polymer according to any one of claims 1 to 5, wherein the amount of the carbon- based heat insulation performance improver is 1 to 15% by weight based on the amount of the particulate foamable polymer. The particulate foamable polymer according to claim 6, wherein the amount of the carbon- based heat insulation performance improving material is 2 to 8% by weight. 6. The particulate expandable polymer according to claim 4 or 5 , wherein the expanded graphite having a particle size of 0.1 to 0.8 μm is obtained by mechanical shearing of a carbon source. The particulate foamable polymer according to any one of claims 1 to 8, wherein the lower limit of the particle size of the carbon- based heat insulating performance improving material is larger than 0.1 µm.   The particulate foamable polymer according to any one of claims 1 to 9, wherein the brominated SBS (styrene-butadiene-styrene) is a block copolymer of polystyrene and brominated polybutadiene.   11. The particulate foamable polymer according to claim 10, wherein the weight percentage of bromine is 60 to 70 wt% based on brominated SBS (styrene-butadiene-styrene).   The particulate foamable polymer according to claim 10 or 11, wherein the weight percentage of styrene is 30 to 50% by weight based on brominated SBS (styrene-butadiene-styrene).   13. The particulate foamable polymer according to claim 10, wherein the molecular weight of the brominated SBS (styrene-butadiene-styrene) is 60000 to 150,000.   14. The amount of brominated SBS (styrene-butadiene-styrene) is 0.7 to 2.2% by weight, based on the total weight of the particulate foamable polymer. A particulate foamable polymer according to any of the above.   15. The particulate form according to any one of claims 1 to 14, wherein the amount of hexabromocyclododecane (HBCD) is less than 1.0% by weight, based on the total weight of the particulate foamable polymer. Expandable polymer.   The polymer is fed into an extruder and mixed with at least a blowing agent, brominated SBS (styrene-butadiene-styrene), carbon having a particle size of less than 1 μm, and one or more other desired auxiliaries and then extruded, The method for producing a particulate foamable polymer according to any one of claims 1 to 15, wherein the particulate foamable polymer is cooled and further reduced to particles.   Monomers, blowing agents, brominated SBS (styrene-butadiene-styrene), and carbon having a particle size of less than 1 μm, and one or more other desired auxiliaries are polymerized in the reactor and optionally cooled in subsequent steps. The method for producing a particulate foamable polymer according to claim 1, wherein the particulate foamable polymer is further reduced to particles. One or more insulation performance improvers selected from the group comprising graphite, carbon black, powdered aluminum, Al (OH) ₃ , Mg (OH) ₂ , Al ₂ O ₃ , iron, zinc, copper, and alloys thereof 18. The method for producing a particulate foamable polymer according to claim 16 or 17, further added as the auxiliary.   A phosphorus compound selected from the group comprising polyphosphonates, diphenylphosphonates, bisphenol A-bis (diphenyl phosphates), and resorcinol aromatic polyphosphate compounds, or combinations thereof is added as said auxiliary agent. Item 19. A method for producing a particulate foamable polymer according to any one of Items 16 to 18.   The particulate foamable polymer-based polymer foam material according to any one of claims 1 to 15. Brominated S BS as a flame retardant containing (- - butadiene styrene styrene), for heat insulation performance improvement of flame retardancy foam particulate expandable polymer system of the polylactic acid, for therein is less than 1μm particle size Of carbon- based heat insulation performance improving material .   Use according to claim 21 in the construction industry.   Use according to claim 21 in the packaging industry.