Ammonium polyphosphate-supported particles as flame retardants in polymer compositions

Abstract

The present invention relates to particles comprising a core containing a water-soluble flame retardant such as ammonium polyphosphate and a shell containing a polyphenol such as lignosulfonate. Such particles can be used as flame retardants in particular polymer foams.

Description

[Technical Field]

[0001] The present invention relates to particles comprising a core containing a water-soluble flame retardant such as ammonium polyphosphate and a shell containing polyphenols, the use of such particles as flame retardants, methods for producing such particles, polymer compositions or foams produced by such methods, and the use of such polymer compositions or foams for the production of flame-retardant products. [Background technology]

[0002] Organic polymers are flammable. Therefore, many polymer applications, such as fibers, foams, and electrical enclosures, require fire protection in the form of added flame retardants. Polymer foams are used, for example, as seat cushions in the furniture industry or generally as energy absorbers or sound and heat insulating materials. In particular, in polymer foams, the large surface area per unit mass of such polymers exacerbates flammability, expanding the requirements for flame retardants. Flame retardants exist that cover and extinguish flames in the gas phase, as well as those that protect the surface of polymeric materials by promoting carbonization or forming a glassy coating. Halogen-containing compounds and nitrogen and phosphorus compounds are preferred flame retardants. Halogen-containing compounds and low-valent phosphorus compounds are considered typical examples of flame retardants that cover and extinguish flames. Higher-valent phosphorus compounds can cause catalytic cleavage of the polymer, resulting in the formation of a solid polyphosphate-containing carbonized surface or a porous carbonaceous surface foam. Both types of layers protect the material from further combustion.

[0003] Typically, mixtures of flame retardants are used to reduce the flammability of polymers. For example, mixtures of trichloropropyl phosphate (TCPP), tris(dichloropropyl) phosphate (TDCPP), and / or melamine may be used.

[0004] The drawbacks of using melamine are that, as a solid, it is not harmless to health and it may be insoluble in the raw materials used. Therefore, when the powder is added to liquid raw materials and stirred, it tends to settle, making industrial processing difficult. Liquid flame retardants such as TCPP do not have these drawbacks. On the contrary, because compounds such as TCPP are relatively volatile, they can interfere with the radical chain reaction that occurs in the flame. As a result, the flame temperature is reduced, and consequently, the decomposition of the ignition material is reduced. However, one drawback of typical halogen-containing examples of this class is that, specifically due to their volatility, they may migrate from the polymer and thereby produce corrosive hydrohalic acids when used in the combustion process.

[0005] The drawbacks mentioned can be partially compensated for by the use of well-known flame-retardant ammonium polyphosphate (APP). However, to achieve optimal performance, the APP needs to be properly dispersed in the polymer. Due to incompatibility with the polymer system, this is often not possible. Furthermore, the solubility of APP in water reduces the weather resistance of the material. To mitigate these effects, protective coatings are applied to the APP particles. For example, Chinese Patent No. 104817676 discloses particles having an APP core and a melamine-based polymer shell. Chinese Patent No. 104448394 describes the use of hydroxy-functionalized acrylate as the shell. However, the coated APP particles mentioned above are not necessarily suitable for use with other polymer systems, such as polylactic acid (PLA), polystyrene (PS), polyamide (PA), polyethylene (PE), and polypropylene (PP), as well as many other polymers. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The object of the present invention is to provide a well-dispersed flame retardant with good settling stability that improves the flame retardancy of polymers such as liquid polymer resins, solid polymer composites, and polymer foams. Preferably, the use of a well-dispersed, settling-stable flame retardant makes it possible to reduce or even replace the amount of halogen-containing flame retardant. A further object of the present invention is to provide a well-dispersed, settling-stable flame retardant that can be made compatible with a wide variety of polymers. [Means for solving the problem]

[0007] In contrast, the present invention provides particles comprising, preferably consisting thereof, a core containing a water-soluble flame retardant and a shell containing a polyphenol, preferably a bio-based polyphenol. The present invention relates to a method for producing such particles (also called capsules), the use of such particles as a flame retardant, a method for producing a flame-retardant polymer composition or foam having such particles, a polymer composition or foam produced by this method, and the use of such polymer composition or foam for the production of several articles.

[0008] Description of the Invention The present invention provides particles comprising, preferably consisting thereof, a core containing a water-soluble flame retardant and a shell containing a polyphenol, preferably a bio-based polyphenol. Preferably, the water-soluble flame retardant has a solubility in water of at least 1 g / mL at 25°C, more preferably at least 1.2 g / mL at 25°C. Preferably, based on the total weight of the core and shell of the particle, the amount of the core corresponds to 65-95% by weight, and the amount of the shell corresponds to 5-35% by weight. More preferably, based on the total weight of the core and shell of the particle, the amount of the core corresponds to 66-90% by weight, for example, 67-85% by weight, and the amount of the shell corresponds to 10-34% by weight, for example, 15-33% by weight.

[0009] Preferably, the water-soluble flame retardant is a polyphosphate, such as an alkali polyphosphate, such as magnesium, sodium, or potassium polyphosphate, or ammonium polyphosphate. More preferably, the water-soluble flame retardant is ammonium polyphosphate. Most preferably, the ammonium polyphosphate of the core of the particles is of formula (I) H[[R 1 R 2 R 3 NH] n [PO3] n OH (I) (wherein R 1 ~R 3 each independently represents H or a substituted or unsubstituted alkyl group, preferably an alkyl group having 1 to 8 carbon atoms, and n is an integer from 4 to 20) corresponds to.

[0010] Particularly preferred is the water-soluble ammonium polyphosphate represented by formula (I) (wherein R 1 ~R 3 each independently represents H, CH3, or CH2CH3, and n is an integer from 4 to 20).

[0011] Preferably, the ammonium polyphosphate (APP) is phase I APP (i.e., linear or unbranched APP). Preferably, the APP has a solubility in water of at least 1 g / mL @ 25 °C, more preferably at least 1.2 g / mL @ 25 °C. The P2O5 content of the polyphosphate is preferably 50 to 70 wt%, more preferably 55 to 65 wt%. The nitrogen content of the polyphosphate is preferably 15 to 25 wt%, more preferably 15 to 20 wt%. Preferably, the polyphosphate has a pH value of 5.5 to 7.5, more preferably 6.7 to 7.0, in a 1% solution in water (w / v (based on the total solution volume)). A given solubility value is at 25 °C unless otherwise defined.

[0012] In addition to polyphosphate, the core may contain other compounds from the group consisting of phosphates, phosphinates, or phosphonates, for example. However, it is preferable if the core contains 50 to 100% by weight, particularly preferably 75 to 100% by weight, and most preferably 100% by weight, of ammonium polyphosphate.

[0013] The particle shell contains polyphenols. Preferably, the polyphenols can be obtained from biomass via extraction, pyrolysis, or fragmentation, and are therefore bio-based. More preferably, the bio-based polyphenols contain structural units derived from one or more of the following: water-soluble lignin, water-soluble tannin, condensed tannin, hydrolyzable tannin, phlorotannin, gallic acid, ellagic acid, phloroglucinol, catechin, profesetidine, prolovinetin, gallocatechin, cashew nut shell liquid, 4-hydroxybenzoic acid, 3,4-hydroxybenzoic acid, caffeic acid, 4-hydroxybenzaldehyde, coniferyl alcohol, vanillin, 4-hydroxyacetophenone, and / or acetovanylone. More preferably, the bio-based polyphenols contain structural units derived from lignin. Even more preferably, the particle shell contains kraft lignin or lignosulfonate, most preferably lignosulfonate.

[0014] Kraft lignin is a byproduct of the kraft process. Lignosulfonates (LS) are sulfonated lignin byproducts from the production of wood pulp using sulfite pulping. Due to the presence of sulfonating groups, lignosulfonates are highly charged at pH 6.0–8.0 and are typically water-soluble. Lignosulfonates have a very wide range of number-average molecular weights, for example, in the range of 1,000–140,000 Da. n Kraft lignin possesses (i.e., is highly polydispersible). LS is non-toxic, non-corrosive, and biodegradable. Kraft lignin generally has lower solubility in water at pH 6.0–8.0 due to its lower degree of sulfonation. However, Kraft lignin is soluble at basic pH above 8.5.

[0015] Preferably, the lignosulfonate has a solubility in water of at least 5 wt%, for example at least 7 wt%, preferably at least 10 wt%, based on the total solution weight, at a pH of 6.0 to 8.0. Preferably, the lignosulfonate has at least 8 mmol / g, more preferably at least 13 mmol / g, for example at least 18 mmol / g of hydroxyl groups.

[0016] The decomposition reaction between the flame retardant and the polymer matrix is minimized due to the introduction of a polyphenol shell around the flame retardant. Moreover, the polyphenol shell can reduce the degradation of the final polymer composition during melt processing.

[0017] In a preferred embodiment, the shell of the particles is substantially melamine-free, acrylate-free, and silicone-free. In this case, the term substantially free can be understood to be free of melamine, acrylate, and silicone in any detectable amount and / or functional amount. Preferably, the shell contains less than 100 weight ppm, more preferably less than 10 weight ppm, and most preferably less than 1 weight ppm of melamine, acrylate, and silicone.

[0018] The particles can also be used as a heterogeneous nucleating agent to increase the foaming properties such as a higher cell density and a smaller cell size.

[0019] The present invention also provides a method for producing the particles of the present invention, the method comprising: - preparing an inverse emulsion of polyphenol, water-soluble flame retardant, emulsifier, and water in an organic solvent, and subsequently - crosslinking the polyphenol with a crosslinking agent, - optionally, grafting the crosslinked polyphenol with a further polymer, and including.

[0020] For example, a reverse emulsion (i.e., a water-in-oil emulsion) can be prepared by first dissolving a polyphenol and a water-soluble flame retardant in water, preparing a solution of an emulsifier in an organic solvent, combining both solutions to form a two-phase mixture, and then emulsifying the two-phase mixture.

[0021] When the water-soluble flame retardant is APP, the pH value of the aqueous solution can be adjusted to 4.0 to 10.0, preferably 5.0 to 9.0, and most preferably 7.0 to 8.0, by adding a base such as sodium hydroxide or an acid such as hydrochloric acid or sulfuric acid.

[0022] Preferably, the amount of water-soluble flame retardant corresponds to 65-95%, for example 66-90%, preferably 67-85% by weight, based on the total weight of the water-soluble flame retardant and polyphenols, and the amount of polyphenols corresponds to 5-35%, for example 10-34%, preferably 15-33% by weight.

[0023] To obtain a uniform droplet size, emulsification can be performed, for example, by ultrasonic emulsification, by emulsification using a microfluidizer, or by emulsification using a rotor-stator system.

[0024] The generation of the particles of the present invention by crosslinking polyphenols may subsequently be carried out by adding a solution of the crosslinking agent in a second organic solvent, in which case the second organic solvent is miscible with the organic solvent of the reverse emulsion, and more preferably the second organic solvent is the same solvent used to prepare the reverse emulsion.

[0025] Due to the preparation of particles in the emulsion, the particles will have a substantially spherical shape. For this reason, preferably, the particles have a substantially spherical shape. Substantially spherical means that the particles have a three-dimensional geometry similar to a sphere, and the maximum diameter does not differ from the minimum diameter by more than 20 percent, preferably more than 10 percent, relative to the minimum diameter. For this reason, the term “substantially spherical” is intended to include minor deviations from a perfect sphere and allow for manufacturing tolerances and other variations, however such deviations must not exceed 20 percent, preferably 10 percent, of the minimum diameter. The particle size distribution can be controlled through three parameters. First, the amount of emulsifier determines the minimum droplet size achievable in the emulsification step. Less emulsifier results in a larger droplet size. The droplet size determines the size of the final particles. Furthermore, processing parameters during emulsification have an effect. For example, in microfluidization, this parameter is the number of runs, which results in a more uniform particle distribution with more runs, and the pressure applied, which typically results in smaller droplets and thus smaller particles with higher pressure. How to modify the parameters to achieve the desired particle distribution will be obvious to those skilled in the art.

[0026] The particle size is preferably 50 nm to 100 μm, more preferably 100 nm to 1 μm, and most preferably 150 nm to 250 nm. Alternatively, the particle size may be 50 to 500 nm. The size is preferably measured by DLS in accordance with ISO 22412:2008, for example, or by the method disclosed below. Alternatively, the size may be determined by TEM by measuring the average diameter of the dry particles, for example, by the method disclosed below. For particles that are not perfectly spherical, the particle diameter measured by TEM is the maximum measurable diameter.

[0027] Smaller particles can achieve the desired flame retardancy with smaller amounts (by weight) compared to larger particles. While not constrained by theory, it is believed that smaller particles result in a more uniform distribution of the flame retardant, and therefore better flame retardancy can be obtained with the same amount of particles. The polydispersity index (PDI) is preferably less than 0.5, preferably less than 0.25, most preferably less than 0.2, for example, 0.05 to 0.15.

[0028] The organic solvent is immiscible with water, i.e., preferably 100 g / dm³ at 25°C. 3 Less than (water), more comfortably 5g / dm 3 The solvent has a solubility in water less than (water) and is preferably easily separated from the crosslinked particles by evaporation, for example, a solvent with a boiling point of less than 150°C at atmospheric pressure, preferably less than 120°C, and more preferably less than 80°C. In preferred embodiments, the organic solvent is pentane or a mixture of pentanes. Pentane is used as a good blowing agent in many polymer foams. By preparing particles in pentane, this process can be easily integrated into standard large-scale foam molding and foam extrusion processes applied on an industrial scale to obtain pentane-expanded polymer particle foams such as EPS (expanded polystyrene) and XPS (extruded polystyrene). Most preferably, the organic solvent is n-pentane or cyclopentane.

[0029] The hydrophilic-lipophilic balance of an emulsifier is a measure of its degree of hydrophilicity or lipophilicity, defined as HLB = 20 Mh / M (wherein Mh is the molecular mass of the hydrophilic portion of the molecule, and M is the molecular mass of the entire molecule), and gives results on a scale of 0 to 20. In principle, any nonionic emulsifier having an HLB value low enough to produce a stable water-in-oil emulsion can be used as an emulsifier. The emulsifier is added in an amount preferably in the range of 0.1% to 8.0%, more preferably 0.5% to 6%, even more preferably 1.0% to 4.0%, and most preferably 1.5% to 3.5% (w / w), based on the amount of the organic phase. The emulsifier is preferably an emulsifier with an HLB value of at most 7, and more preferably the emulsifier is polyglycerol polyricinolate (PGPR, E476). Preferably, the PGPR has a degree of polymerization of 1 to 10, more preferably 1 to 4.

[0030] The crosslinking agent is preferably a polyisocyanate, for example, an aliphatic, cyclic aliphatic, aromatic aliphatic, aromatic, or heterocyclic polyisocyanate, for example, formula (II) Q(NCO) n (II) (In the formula, n is an integer between 2 and 4, preferably 2 or 3, and Q is an aliphatic hydrocarbon group having 2 to 18 carbon atoms, preferably 6 to 10; a cyclic aliphatic hydrocarbon group having 4 to 15 carbon atoms, preferably 6 to 13; an aromatic hydrocarbon group having 6 to 10 carbon atoms; or an aromatic aliphatic hydrocarbon group having 8 to 15 carbon atoms, preferably 8 to 13 carbon atoms. This corresponds to the above.

[0031] Particularly preferred are technically readily accessible polyisocyanates, such as 2,4- and 2,6-toluylene diisocyanates, or mixtures of any of these isomers ("TDIs"), polyphenylpolymethylene polyisocyanates, such as those prepared by aniline-formaldehyde condensation followed by phosgenation ("crude MDIs"), and polyisocyanates containing carbodiimide groups, urethane groups, allophanate groups, isocyanurate groups, urea groups, or biuret groups ("modified polyisocyanates" or "prepolymers"), specifically modified polyisocyanates derived from 2,4- and / or 2,6-toluylene diisocyanate and / or diphenylmethane 4,4'- and / or 2,4- and / or 2,2''-diisocyanate. Preferably, at least one compound selected from the group consisting of 2,4- and 2,6-toluylene diisocyanates, diphenylmethane 4,4'- and 2,4'- and 2,2'-diisocyanates, and polyphenylpolymethylene polyisocyanates ("multinuclear MDI") is used as a crosslinking agent.

[0032] A mixture of diphenylmethane diisocyanate and polyphenylene polymethylene polyisocyanate ("multinuclear MDI" or "pMDI") has a preferred monomer content of 50-100 wt%, preferably 60-95 wt%, and particularly preferably 75-90 wt%. The NCO content of the polyisocyanate used should preferably be greater than 25 wt%, preferably greater than 30 wt%, and particularly preferably greater than 31.4 wt%. Preferably, the MDI used should have a 2,4'-diphenylmethane diisocyanate content of at least 3% by weight, preferably at least 15% by weight.

[0033] In addition to the polyisocyanates listed above, modified diisocyanates having uretdione groups, isocyanurate groups, urethane groups, carbodiimide groups, uretonimine groups, allophanate groups, biuret groups, amide groups, iminooxadiadindione groups, and / or oxadiadintrione groups, as well as unmodified polyisocyanates having more than 2 NCO groups per molecule, such as 4-isocyanatomethyl-1,8-octanediisocyanate (nonane triisocyanate) or triphenylmethane-4,4',4”-triisocyanate, may also be used in combination.

[0034] The particles produced after crosslinking polyphenols with a crosslinking agent can be easily dispersed in a polymer matrix with chemical properties comparable to those of the polyphenols or emulsifiers.

[0035] However, in order to allow dispersion in other—particularly more polar—polymer matrices, it may be necessary to graft the cross-linked polyphenols with additional polymers. For this reason, the particle shells may be grafted with additional polymers.

[0036] In this case, a miscible oligomer or polymer, preferably exactly the same as the polymer matrix, can be grafted onto the particle surface. This grafting ensures colloidal stability when the particles are redispersed into the polymer matrix. Preferably, the oligomer or polymer is OH-functionalized or NH2-functionalized, most preferably OH-functionalized. Preferably, the weight ratio of the solids (i.e., particles including the core and shell with added emulsifier) ​​to the graft polymer is about 1:1, for example, 0.5:1 to 2:1, preferably 0.8:1 to 1.25:1.

[0037] To produce a flame-retardant polymer composition, following the above-mentioned method for producing particles, the following: - The step of adding a matrix polymer, - A step to remove the organic solvent, This can happen.

[0038] The steps may be carried out in the order listed above, or the step of removing the organic solvent may be performed prior to the step of adding the matrix polymer. When the organic solvent is first removed, the remaining particles may be mixed with the thermoplastic matrix polymer, for example, in a compound mixer or a melt compounding system (either tangential or interlocking rotor geometry). Otherwise, an extrusion process (e.g., sheet film extrusion, blow film extrusion, overjacketing extrusion, tubing extrusion, morph extrusion, co-extrusion, extruded coating) may be used to disperse the particles in the polymer matrix and to further process the composition.

[0039] Preferably, the matrix polymer is added before the removal of the organic solvent, as this results in a more uniform particle distribution in the composition. Preferably, the matrix polymer is added as a solution in an organic solvent, preferably a solvent miscible with the solvent used to prepare the reverse emulsion, most preferably the same solvent used to prepare the reverse emulsion. For example, to produce a flame-retardant polylactic acid (PLA) composition, a solution of PLA may be added to a reverse emulsion having crosslinked particles, and the solvent is then evaporated, for example, by heating, distillation, and / or rotary evaporation, or any other evaporation technique known to those skilled in the art. The result is a polymer matrix having dispersed flame-retardant particles, i.e., a flame-retardant polymer composition.

[0040] Preferred matrix polymers are flammable polymers, i.e., polymers that do not pass the UL94 test in accordance with ISO9772:2020 or ISO9773:1998, and / or polymers with an LOI index lower than 20% in accordance with ISO4589-2. Particularly preferred matrix polymers are liquid polymer resins, such as acrylates, polyurethane acrylates, and methacrylate polymers, such as acrylic oils, acrylic vegetable oils, ethoxylated bisphenol A dimethacrylate (Bis-EDA), bisphenol A glycidyl methacrylate (Bis-GMA), poly-(ethylene glycol)-diacrylate (PEGDA), urethane dimethacrylate (UDMA), triethylene glycol dimethacrylate (TEGDMA), and trimethylolpropane triacrylate (TTA). Further preferred matrix polymers include thermoplastic polymers, such as polystyrene and its derivatives (e.g., cross-linked polystyrene), polylactic acid (PLA), thermoplastic polyurethanes, polyamides (e.g., PA6), polymethacrylates (e.g., PMMA), polyolefins (e.g., polyethylene (PE), polypropylene (PP)), polyesters, polyethers, and / or copolymers and / or blends thereof.

[0041] Preferably, the flame-retardant polymer composition contains 1 to 50 wt%, more preferably 5 to 25 wt%, even more preferably 7 to 19 wt%, and most preferably 9 to 18 wt%, of the total weight of the composition, particles. Preferably, the flame-retardant polymer composition contains at least 5 wt%, more preferably at least 7 wt%, and even more preferably at least 9 wt%, particles.

[0042] Alternatively, to produce a flame-retardant polymer composition, following the method for producing particles, the following: - The step of adding a reactive monomer or oligomer A, - Steps to remove organic solvents, - The step of adding a further reactive monomer or oligomer B, -A step of reacting A and B with each other, This can happen.

[0043] This method, in which the organic solvent is removed before the addition of B, is particularly suitable for producing crosslinked flame-retardant polymer compositions such as crosslinked polyurethane compositions. In the latter case, the reactive monomer or oligomer A is a compound having a hydrogen atom reactive with isocyanate, and B is a polyisocyanate, for example, one of the polyisocyanates mentioned earlier.

[0044] This method is also suitable for producing thermoplastic compositions from different bifunctional monomers or oligomers, in which case the step of removing the organic solvent may be carried out after the step of reacting A and B.

[0045] To produce flame-retardant polymer foam, the method for producing a flame-retardant polymer composition according to the present invention further includes: - Step of adding a foaming agent, This includes the following. The blowing agent may be added at any point in this method, and it is not necessary to add the blowing agent as the final step. Chemical and / or physical blowing agents may be used. However, in the case of a physical blowing agent, it is preferable to add the blowing agent as the final step.

[0046] In some cases, organic solvents can also act as blowing agents, and in such cases, it is not always necessary to remove all organic solvents in the step of removing them. Preferred organic solvent blowing agents are cyclopentane, cyclohexane, n-pentane, n-hexane, or toluene. Pentane is used as a preferred blowing agent in many polymer foams. By preparing particles in one of the solvents listed above, particularly pentane, and especially n-pentane or cyclopentane, this process can be easily integrated into standard large-scale foam molding processes applied at an industrial scale to obtain pentane-expanded polymer particle foams such as EPS (expanded polystyrene) and XPS (extruded polystyrene).

[0047] Chemical blowing agents react with a polymer matrix or one of a reactive monomer or oligomer to form a foaming gas. For example, water or carboxylic acids and mixtures thereof can be used as chemical blowing agents. In the production of polyurethane foam, these react with isocyanate groups to form a foaming gas; for example, in the case of water, carbon dioxide is formed, and in the case of formic acid, carbon dioxide and carbon monoxide are formed. Preferably, at least one compound selected from the group consisting of formic acid, N,N-dialkylcarbamic acid, oxalic acid, malonic acid, and ricinoleic acid is used as the carboxylic acid. Ammonium salts of these acids are also suitable. Water is particularly preferred as a chemical blowing agent.

[0048] Physical blowing agents include, for example, low-boiling-point organic compounds such as hydrocarbons, ethers, ketones, carboxylic acid esters, carbonate esters, and halogenated hydrocarbons or CO2. Organic compounds having a boiling point of less than 100°C at atmospheric pressure, preferably less than 50°C, are particularly preferred. Examples of such preferred organic compounds include alkanes, such as n-heptane, n-hexane, n- and iso-pentane, preferably technical mixtures of n- and iso-pentane, n- and iso-butane, and propane; cycloalkanes, such as cyclopentane and / or cyclohexane; ethers, such as furan, dimethyl ether, and diethyl ether; ketones, such as acetone and methyl ethyl ketone; alkyl carboxylates, such as methyl formate, dimethyl oxalate, and ethyl acetate; and halogenated hydrocarbons, such as methylene chloride, difluoromethane, trifluoromethane, difluoroethane, tetrafluoroethane, 1,1-dichloro-2,2,2-trifluoroethane, 2,2-dichloro-2-fluoroethane, and heptafluoropropane. Furthermore, the use of (hydro)fluorinated olefins as additives is also preferred, such as HFO1233zd(E) (trans-1-chloro-3,3,3-trifluoro-1-propene) or HFO1336mzz(Z) (cis-1,1,1,4,4-hexafluoro-2-butene) or FA188 (1,1,1,2,3,4,5,5-nonafluoro-4-(trifluoromethyl)pento-2-ene) from 3M. It is also possible to use mixtures of two or more of the above organic compounds. In connection with this, the organic compounds may also be used in the form of small droplet emulsions.

[0049] The method according to the present invention for preparing flame-retardant polymer compositions and / or foams may include the addition of further flame retardants. Preferably, the further flame retardants contain melamine and / or do not contain halogen-containing compounds. Examples of further flame retardants include, for example, melamine, phosphates, or phosphonates, such as diethylethanephosphonate (DEEP), triethyl phosphate (TEP), and dimethylpropylphosphonate (DMPP). Other suitable flame retardants include brominated esters, brominated ethers (Ixol), or brominated alcohols, such as dibromoneopentyl alcohol, tribromoneopentyl alcohol, tetrabromophthalate diol (DP54), and PHT-4 diol; as well as chlorinated phosphates, such as tris(2-chloroethyl) phosphate, tris(2-chloropropyl) phosphate (TCPP), tris(1,3-dichloropropyl) phosphate, tricresyl phosphate, diphenylcresyl phosphate (DPK), tris(2,3-dibromopropyl) phosphate, tetrakis(2-chloroethyl)ethylenediphosphate, dimethylmethanephosphonate, diethyl diethanolaminomethylphosphonate, and commercially available halogen-containing flame retardant polyols.

[0050] The present invention provides a method for preparing flame-retardant polymer compositions and / or foams, which includes excipients and / or additives, for example, a) Catalyst (activator), b) Surface-active additives (surfactants), such as emulsifiers and foam stabilizers, especially low-emission products such as those in the Tegostab® LF series. c) Additives such as reaction retarders (e.g., acidic reactive substances such as hydrochloric acid or organic acid halido), cell modifiers (e.g., kerosene or fatty alcohol or dimethylpolysiloxane), pigments, dyes, stabilizers against aging and weathering, plasticizers, fungistatic and bacteriostatic substances, fillers (e.g., barium sulfate, diatomaceous earth, carbon black, or whiting), and release agents. This may include further steps of adding [something].

[0051] The present invention further provides polymer compositions or foams produced by methods according to the present invention, and the use of such polymer compositions or foams for the production of flame-retardant coatings, textiles, upholstery, textile inserts, mattresses, automotive seats and automotive structural components, headrests, armrests, sponges, headliners, door panels, seat covers, packaging materials, or building elements.

[0052] Preferably, the polymer composition or foam according to the present invention contains 1 to 25 wt%, preferably 4 to 21 wt%, and more preferably 5 to 15 wt%, of the particles according to the present invention, based on the total weight of the polymer composition or foam. [Brief explanation of the drawing]

[0053] [Figure 1] A schematic diagram of the method according to the present invention is shown. [Figure 2] The DLS graph shows particles containing an APP core and a lignin shell (LP) in cyclohexane (average from 3 measurements, Z mean = 240 nm, PDI = 0.13). [Figure 3] Electron microscope images of LP are shown (left: SEM, right: TEM). [Figure 4] The image shows SEM images of CO2 foamed PLA foam supported with 13% LP (top: overview, bottom left: magnified, bottom right: backscatter image; in this case, the bright areas suggest the presence of phosphorus). [Modes for carrying out the invention]

[0054] Detailed explanation of Figure 1 In Figure 1, a two-phase mixture is prepared from polyphenol 4 and water-soluble flame retardant 3 in water 1 and emulsifier 5 in organic solvent 2. In step A, the two-phase mixture is emulsified to form a reverse emulsion 9. In step B, a crosslinking agent 6 is added to form particles 10. In step C, a hydroxyl or amine-functionalized monomer, oligomer, or polymer 7 is added to form functionalized particles 11. Finally, in step D, a polymer matrix 8 is added and the solvent is evaporated to form a flame-retardant polymer composition. [Examples]

[0055] Explanation of the experiment particle synthesis raw materials Lignosulfonate (TCI, Prod. No.: L0098, #V5VJF-NC), ammonium polyphosphate (APP111, water-soluble, Connect Chemicals GmbH, Germany), polyglycerol polyricinolate (Grinsted PGPR, Danisco, #4012754390, Mat.: 033624), cyclohexane (≧99%, VWR), toluene-2,4-diisocyanate (≧95%, TDI, Sigma Aldrich), toluene (≧99.5%, VWR), 3,6-dimethyl-1,4-dioxan-2,5-dione (≧99%, Sigma Aldrich), dichloromethane (anhydrous, ≧99.8%, VWR), 1,8-diazabicyclo[5.4.0]undec-7-ene (≧98%, Sigma Aldrich) Aldrich), methanol (anhydrous ≥99.9%, VWR), petroleum ether (≥99%, VWR), polylactic acid (PLA, Natureworks Ingeo 4060D).

[0056] Device Microfluidizer LM10, Branson ultrasonic tip SFX 550, Malvern Zetasizer Lab, rotary evaporator Buechi R200 (Buechi V-500 or Edwards RV3) with membrane or oil pump, dynamic light scattering Malvern Zetasizer Lab, centrifuges (Hermle Z36HK and Phoenix CD-3124R), scanning electron microscope Hitachi SU8400, transmission electron microscope Zeiss EM91, FT-IR spectrometer (Bruker Alpha-P ATR), thermogravimetric analyzer (TA instruments TGA550), vacuum oven VOS-12051 (VOS instrumenten) with membrane pump KNF PM23973-920, hot press (THB 400, Fontijne, Delft, Netherlands), high-pressure laboratory autoclave (Carl Roth, Model II, 200 mL / 100 bar), Autoclave HMC Hiclave HG50 (HMC Europe GmbH, Germany).

[0057] PGPR purification Optionally, PGPR was purified from the insoluble aggregate before use. Therefore, 120 g of PGPR was dissolved in 600 mL of cyclohexane at room temperature in a 1 L round-bottom flask. The PGPR solution was then transferred to four 250 mL centrifuge bottles, tare-weighted, and centrifuged at 9000 rpm for 10 min. The colorless pellet was discarded. The clear supernatant was transferred to a 1 L round-bottom flask. Cyclohexane was then completely removed from the solution using a rotary evaporator (40°C, 140 mbar). A clear yellow viscous liquid was obtained.

[0058] Dispersion of particles having an APP core and a lignin shell in cyclohexane An aqueous phase consisting of 15 g of lignosulfonate in 195 g of water was prepared in a 1 L laboratory bottle. After completely dissolving the lignosulfonate at room temperature, the solution was autoclaved at 121°C for 40 min and then removed from the autoclave. Next, 36 g of ammonium polyphosphate was added to the lignosulfonate solution and dissolved at room temperature. Subsequently, an organic phase consisting of 12 g of purified PGPR and 587 g of cyclohexane was added. Optionally, particle preparation was carried out in cyclopentane (566 g, 754 mL) or toluene (653 g, 754 mL) as the organic phase. Subsequently, the two-phase mixture was pre-emulsified using a Branson SFX250 ultrasonic tip (2 min, 70% amplitude, 30 s sonication, 10 s pause). Both macroscopic precipitates were separated from the pre-emulsification by filtration through open-pore filter paper. Next, emulsification was performed using an LM10 microfluidizer (6000 psi, 4 runs). This yielded a droplet size of 200 nm with a PDI of 0.1. The emulsion was then transferred to a 2 L flask and stirred at 500 rpm using a magnetic stirrer. A freshly prepared crosslinking agent solution consisting of 3.6 g TDI and 1.7 g purified PGPR in 182.9 mL of organic solvent (either cyclohexane, cyclopentane, or toluene) was added via a 500 mL dropping funnel (approximately 2 drops / second). The dispersion was then stirred overnight at 600 rpm using an elliptical stirrer at room temperature. The following day, stirring was stopped for 2 hours to decant any settling flocculations, and the dispersion was subsequently stored in laboratory bottles.

[0059] Dispersion of particles having an APP core and lignin shell in a thermoplastic matrix (e.g., PLA) PLA oligomer synthesis PLA oligomers were synthesized from racemic D,L-lactide by ring-opening polymerization at a lactide-to-initiator ratio of 100:1, corresponding to 200 lactic acid repeating units. First, a 200 mL Schlenk flask was purged three times, switching between vacuum and nitrogen. Then, the flask was flame-dried to remove trace amounts of water. 17 g of racemic D,L-lactide (117.9 mmol) was added to the flask. Subsequently, 90 mL of anhydrous dichloromethane was added to the flask, and the solution was stirred under nitrogen for 1 hour to completely dissolve the monomer. Next, a 0.315 M solution of 1,8-diazabicyclo(5.4.0)undec-7-ene in 0.315 mmol of anhydrous dichloromethane was added to the flask. Next, a 1.179 M solution of 1 mL of methanol in anhydrous dichloromethane (1.179 mmol) was added to the flask, and the reaction was allowed to proceed for 2 hours at room temperature under nitrogen. Finally, the crude product was precipitated in 900 mL of petroleum ether and filtered under vacuum. The resulting PLA powder was dried overnight in a vacuum oven at 50°C.

[0060] PLA grafting onto lignin particles (PLA-g-LP) Toluene was added to a lignin particle dispersion in cyclohexane in a 1:1 (v / v) ratio while stirring. The cyclohexane was then evaporated using a rotary evaporator (25°C, 105 mbar). Next, PLA oligomer was dissolved in toluene at 60°C (c=4 wt%). The PLA oligomer solution was cooled to room temperature and added dropwise to the stirred lignin particle dispersion in toluene. The ratio of solids from the dispersion to the amount of PLA oligomer was set to 1:1 (wt / wt). The flask was then stirred overnight at room temperature to graft the PLA oligomer onto the surface of the lignin particles.

[0061] Preparation of PLA composites PLA composites containing 5 wt%, 9 wt%, 13 wt%, and 20 wt% APP-supported PLA-g-LP were prepared. First, PLA was dissolved in toluene at a concentration of 7.5 wt% with stirring overnight at 80°C. Next, the PLA solution was added dropwise to a stirred lignin particle dispersion in toluene. The resulting mixture was characterized by DLS. Subsequently, the toluene was evaporated from the mixture by rotary evaporation, and the composite was collected in a Petri dish. Finally, the resulting composite was dried from the remaining toluene residue in a fume hood at room temperature for 24 hours, followed by drying in a vacuum oven at 70°C for 24 hours.

[0062] Hot pressing of composites PLA composites and raw PLA pellets were hot-pressed to prepare sticks with dimensions of l=10cm, b=0.5cm, and h=1.5mm. The hot-press stage was preheated to either 70°C for hot-pressing 20wt% APP-supported PLA-g-LP composites or 80°C for hot-pressing other PLA composites and raw PLA pellets. Small pieces of PLA composite or raw PLA pellets were placed in a rectangular pattern mold with dimensions of l=10cm, b=0.5cm, and h=1.5mm. PTFE sheets and aluminum plates were inserted between the mold and the upper and lower stages of the hot-press. Initially, the sample was preheated at a pressure of 20kN for 40 minutes. Then, the sample was pressed at 100kN for 10 minutes. Subsequently, the stage was cooled to room temperature. Finally, the resulting hot-pressed sample was removed from the stage and recovered from the mold.

[0063] PLA CO2 batch foaming process PLA foam was prepared by enclosing a hot-pressed PLA sample in a high-pressure autoclave at room temperature. First, the stick was sealed in a high-pressure vessel. Then, the vessel was flushed with low-pressure CO2 for 30 seconds. Subsequently, the pressure was increased to 30 bar to foam the hot-pressed raw PLA or to 40 bar to foam the hot-pressed PLA composite. CO2 saturation was carried out for 6 hours. Then, the vessel was depressurized. The sample was removed from the vessel and immersed in a 60°C water bath, followed by quenching in an ice bath for 10 seconds. Finally, the resulting foam was dried at room temperature. For SEM analysis, the foam was further dried overnight under vacuum at 60°C.

[0064] Characterization Solids of lignin particle (LP) dispersion A 200 μL dispersion of particles containing an APP core and a lignin shell in cyclohexane was placed in a 1 mL glass vial, and the solvent was evaporated (2 h, 70°C). Subsequently, the solids content was determined by differential weighing. Typically, a solids content of 5.7 ± 0.3% was obtained.

[0065] Dynamic light scattering (DLS) Particle size was measured using a Malvern Zetasizer Lab at 25°C and a scattering angle of 90°, employing a general-purpose analytical model. 2.5 μL of particle dispersion was diluted in 800 μL of fresh cyclohexane in a glass cuvette, with the attenuator set to steps 10-11 (automatically set by the device). Data analysis was performed using Malvern Panalytical's ZSxplorer 2.2.0.147 software. Three measurements were performed for each sample.

[0066] Particle electron microscopy 500 μL of dispersion was centrifuged three times at 1400 g over 30 min in a 1 mL microreaction tube. After each centrifugation, the supernatant was removed and the resulting pellet was redispersed in 500 μL of fresh cyclohexane (30 s vortex and 15 min sonication). After the final redispersion, 10 μL of the sample was diluted in 800 μL of fresh cyclohexane. 2 μL of this diluted sample was placed on a Si wafer or carbon surface, and the solvent was evaporated overnight at room temperature. Particle imaging was then performed via SEM. For TEM imaging, 1 μL of the diluted sample was dropped onto a copper grid, and the solvent was evaporated at room temperature.

[0067] Thermogravimetric analysis (TGA) In a titanium crucible, under a nitrogen atmosphere, at a temperature range of 25°C to 600°C, for 10 Kmin. -1 At the heating rate, a 2 mg dry particle dispersion from cyclohexane was analyzed.

[0068] Electron microscopy of foam Secondary electron microscopy (SEM) was used to characterize the CO2-foamed PLA foam. Therefore, prior to SEM imaging, the foam was cooled in liquid nitrogen and then freeze-fractured for 10 minutes. Secondary electron analysis and backscatter electron analysis were performed. Imaging parameters are shown in Figure 4.

[0069] SEM backscatter electron analysis shows that the particles are uniformly distributed throughout the foam (Figure 4).

[0070] Cell density and nucleation efficiency Cell diameter and cell density were obtained for each form by analyzing SEM cross-sectional images containing at least 100 cells using ImageJ software. The average cell diameter D was directly determined from the SEM cross-sectional images.

[0071] Limiting Oxygen Index (LOI) The LOI index was determined in accordance with ISO 4589-2. LOI represents the minimum level of atmospheric oxygen that sustains a flame on a polymer material.

[0072] UL94 grade The UL94 rating was determined in accordance with ISO9772:220 and ISO9773:1998.

[0073] Grade V-2 indicates that the flame burn stops within 30 seconds after two 10-second applications of a blue Bunsen burner flame, and flaming drip is acceptable.

[0074] Grade V-1 indicates that the blue Bunsen burner flame should be applied for 10 seconds twice each, followed by the flame burning stopping within 30 seconds, and flame dripping is not permitted.

[0075] Grade V-0 indicates that the blue Bunsen burner flame should be applied for 10 seconds twice, with the flame burning stopping within 10 seconds thereafter, and flame dripping is not permitted.

[0076] [Table 1]

[0077] Table 1 shows that 5 wt% particles already provide a significantly improved flame retardancy, and 9 wt% particles further achieve a V0 rating. In comparison, when PLA is flame-retardant with inorganic fillers such as aluminum trihydrate, a high loading concentration of approximately 50 wt% is typically required to achieve a V0 rating (see Bourbigot et al., Polym. Chem. 2010, 1, 1413-1422). In the case of phosphates such as melamine polyphosphate and ammonium phosphate-functionalized lignin, typically 20 wt% of additives are required to achieve a V0 rating in PLA (see Bourbigot et al., Molecular Crystals and Liquid Crystals 486, 2008, 1, 325-339, and Costes et al., European Polymer Journal 2016, 84, 652-667).

[0078] Table 1 shows that the mechanical properties (elongation at fracture, Young's modulus, and tensile strength) of the 9wt% experiment are comparable to those of raw PLA. The addition of particles does not significantly affect the mechanical properties of PLA.

[0079] Repeat the 9 wt% experiment shown in Table 1 with larger particles (10 μm as measured by TEM). This results in a lower UL-94 rating.

[0080] [Table 2]

[0081] Table 2 shows that 5 wt% particles increase the form cell density by an order of magnitude and reduce the average form cell diameter from 63 μm to 29 μm (46%), while maintaining a constant form cell diameter and density up to 13 wt% particles.

[0082] The present invention further relates to the following items.

[0083] 1. Particles comprising a core containing a water-soluble flame retardant and a shell containing a polyphenol, preferably a bio-based polyphenol.

[0084] 2. The particle described in item 1, characterized in that, based on the total weight of the particle's core and shell, the amount of the particle's core corresponds to 65-95% by weight, and the amount of the particle's shell corresponds to 5-35% by weight.

[0085] 3. The particles according to item 1 or 2, wherein the particles have a size of 50 nm to 100 μm, more preferably 100 nm to 1 μm, and most preferably 150 nm to 250 nm.

[0086] 4. The water-soluble flame retardant is a polyphosphate, preferably ammonium polyphosphate, and more preferably ammonium polyphosphate is of formula (I) H[[R 1 R 2 R3 NH] n [PO3] n ]OH (I) (In the formula, R 1 ~R 3 This independently represents H or a substituted or unsubstituted alkyl group, preferably an alkyl group having 1 to 8 carbon atoms, and n is an integer between 4 and 20. A particle corresponding to one of items 1-3.

[0087] 5. A particle according to any one of items 1 to 4, wherein the particle shell comprises a polyphenol comprising structural units derived from lignin, preferably lignosulfonate, more preferably lignosulfonate having a solubility in water of at least 5 wt% at pH 6.0 to 8.0 and / or having at least 8 mmol / g of hydroxyl groups.

[0088] 6. A particle described in any one of items 1-5, wherein the particle shell is grafted with an additional polymer.

[0089] 7. Use of particles listed in any one of items 1-6 as flame retardants.

[0090] 8. A method for producing particles described in any one of items 1 to 6, wherein the method is as follows: -Preparing a reverse emulsion of polyphenols, a water-soluble flame retardant, an emulsifier, and water in an organic solvent, - Crosslinking polyphenols with a crosslinking agent, -Optionally, grafting cross-linked polyphenols with further polymers, Methods that include...

[0091] 9. Organic solvents, branched or unbranched C 5~8 Alkane, C 5~8 Cycloalkanes, and C 5~8The method according to item 8, wherein the organic solvent is selected from aromatics, more preferably cyclopentane, cyclohexane, n-pentane, n-hexane, or toluene, and most preferably the organic solvent is cyclopentane or n-pentane.

[0092] 10. Following the method described in item 8 or 9, the following: - The step of adding a matrix polymer, - Steps to remove organic solvents, A method for producing a flame-retardant polymer composition containing [a specific substance].

[0093] 11. The method according to item 10, wherein a step of removing the organic solvent is performed prior to the step of adding the matrix polymer, and the particles are mixed with the thermoplastic matrix polymer, preferably in a compound mixing process, an extrusion process, or an injection molding process.

[0094] 12. Following the method described in item 8 or 9, the following: - The step of adding a reactive monomer or oligomer A, - Steps to remove organic solvents, - The step of adding a further reactive monomer or oligomer B, -A step of reacting A and B with each other, A method for producing a flame-retardant polymer composition containing [a specific substance].

[0095] 13. A method for producing a flame-retardant polymer foam, comprising the method described in any one of items 10 to 12, further comprising the step of adding a blowing agent.

[0096] 14. A polymer composition or foam produced by any one of the methods described in item 8 to 13.

[0097] 15. Use of polymer compositions or foams described in item 14 for the production of flame-retardant coatings, textiles, upholstery, textile inserts, mattresses, automotive seats, headrests, armrests, sponges, headliners, door panels, seat covers, or building elements.

Claims

1. Particles comprising a core containing a water-soluble flame retardant and a shell containing a polyphenol, preferably a bio-based polyphenol, wherein the particles have a size of 100 nm to 1 μm as measured by DLS, and the water-soluble flame retardant has a solubility of at least 1 g / ml in water at 25°C.

2. The particle according to claim 1, characterized in that, based on the total weight of the core and the shell of the particle, the amount of the core of the particle corresponds to 65 to 95% by weight, and the amount of the shell corresponds to 5 to 35% by weight.

3. The particle according to claim 1 or 2, wherein the particle has a size of 150 nm to 250 nm.

4. The water-soluble flame retardant is a polyphosphate, preferably ammonium polyphosphate, and more preferably the ammonium polyphosphate is of formula (I) H[[R １ R ２ R ３ NH] ｎ [PO ３ ] ｎ ]OH (I) (In the formula, R １ ~R ３ This independently represents H or a substituted or unsubstituted alkyl group, preferably an alkyl group having 1 to 8 carbon atoms, and n is an integer between 4 and 20. A particle according to any one of claims 1 to 3, corresponding to the particle described in claim 1 to 3.

5. The particle according to any one of claims 1 to 4, wherein the shell of the particle comprises a polyphenol comprising a structural unit derived from lignin, preferably a lignosulfonate, more preferably a lignosulfonate having a solubility in water of at least 5 wt% at a pH of 6.0 to 8.0 and / or a structural unit having at least 8 mmol / g of hydroxyl groups.

6. The particle according to any one of claims 1 to 5, wherein the shell of the particle is grafted with a further polymer.

7. Use of the particles described in any one of claims 1 to 6 as a flame retardant.

8. A method for producing particles according to any one of claims 1 to 6, wherein the method is as follows: - Preparing a reverse emulsion of polyphenols, a water-soluble flame retardant, an emulsifier, and water in an organic solvent, - Crosslinking the polyphenol with a crosslinking agent, - Optionally, the cross-linked polyphenol may be grafted with a further polymer, Methods that include...

9. The organic solvent is a branched or unbranched C ５～８ alkane, C ５～８ cycloalkane, and C ５～８ aromatic selected, more preferably the organic solvent is cyclopentane, cyclohexane, n-pentane, n-hexane, or toluene, and most preferably, the organic solvent is cyclopentane or n-pentane, the method according to claim 8.

10. The method described in claim 8 or 9, followed by: - The step of adding a matrix polymer, - The step of removing the organic solvent, A method for producing a flame-retardant polymer composition containing [a specific substance].

11. The method according to claim 10, wherein the step of removing the organic solvent is performed prior to the step of adding the matrix polymer, and the particles are mixed with the thermoplastic matrix polymer, preferably in a compound mixing process, an extrusion process, or an injection molding process.

12. The method described in claim 8 or 9, followed by: - A step of adding a reactive monomer or oligomer A, - The step of removing the organic solvent, - The step of adding a further reactive monomer or oligomer B, - A step of reacting A and B with each other, A method for producing a flame-retardant polymer composition containing [a specific substance].

13. A method for producing a flame-retardant polymer foam, comprising the method according to any one of claims 10 to 12, further comprising the step of adding a blowing agent.

14. A polymer composition or foam produced by the method described in any one of claims 8 to 13.

15. Use of the polymer composition or foam according to claim 14 for the production of flame-retardant coatings, textiles, upholstery, textile inserts, mattresses, automotive seats, headrests, armrests, sponges, headliners, door panels, seat covers, or building elements.

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