JP5596702B2 - Microsphere - Google Patents

Description

  The present invention relates to thermally expandable thermoplastic microspheres, their production and use.

  Expandable thermoplastic microspheres containing a thermoplastic polymer shell encapsulating a propellant are marketed under the trademark EXPANCEL® and used as a foaming agent in many different applications Is done.

In such microspheres, the blowing agent is usually a liquid whose boiling point is not higher than the softening temperature of the thermoplastic polymer shell. When heated, the foaming agent softens the shell and at the same time evaporates to increase the internal pressure, and the microspheres expand greatly. Temperature at which the expansion starts is called T _start (T _start), the temperature at which the expansion reaches a maximum is called the T _maximum (T _max). Expandable microspheres are commercially available in a variety of forms, for example, as free-flowing dry particles, as an aqueous slurry, or as a partially dehydrated wet cake.

  Expandable microspheres can be produced by polymerizing ethylenically unsaturated monomers in the presence of a blowing agent. Usually, the monomer mainly comprises a monomer having one carbon-carbon double bond together with a small amount of a crosslinking monomer having two or more carbon-carbon double bonds. A detailed description of various expandable microspheres and their production is described, for example, in U.S. Pat. Nos. 3,615,972, 3,945,956, 4,287,308, 5,536,756, 6,235,800, 6,235,394, and 6,509,363, 6,617,363. And US Pat. No. 6,984,347, U.S. Patent Application Publication Nos. 2004/0176486 and 2005/0079352, European Patent No. 486,080, European Patent No. 1230975, European Patent No. 1288272, European Patent No. 1598405, In European Patent No. 1811007 and European Patent No. 1964903, International Publication No. WO 2002/096635, International Publication No. 2004/072160, International Publication No. 2007/091960, International Publication No. 2007/09. 961 No., and in WO 2007/142593, and it can be known in JP 1987-286534 and JP 2005-272633.

One important application of expandable microspheres is as a forming agent for processing polymer materials, for example, in injection molding, extrusion and the like. In some cases, microspheres are pre-processed with polymers and optionally various additives to produce well-mixed formulations that can be used later in, for example, injection molding, extrusion, thermoforming. It is desirable to provide microspheres having a high T _start in combination with a T _{maximum that} is not too high. Such mixing steps, such as compounding, must be performed at a sufficiently high temperature such that the polymer melts but there is no pre-expansion of the microspheres. With this pre-expansion, for example, the extruder may be blocked and the expansion capacity of the final blend may be significantly reduced.

An object of the present invention, together with a clear expansion at relatively close temperatures T _start, is to provide an expansion capability is high expandable microspheres and a high resistance to a relatively high T _start and preexpanded .

  Another object of the present invention is to provide expandable microspheres useful as a forming agent for thermoplastic materials.

  Surprisingly, it is possible to achieve this goal by providing expandable microspheres comprising at least two different types of cross-linking monomers, one monomer being highly reactive and one being less reactive. There was found.

  Accordingly, one aspect of the present invention is a thermally expandable thermoplastic microsphere comprising a polymer shell prepared from an ethylenically unsaturated monomer encapsulated with a blowing agent, the ethylenically unsaturated monomer comprising two Including at least one first crosslinking monomer having the above carbon-carbon double bond and at least one second crosslinking monomer having two or more carbon-carbon double bonds, wherein the at least one first The cross-linking monomer has a reactivity Q of greater than 0.2, and the at least one second cross-linking monomer has a reactivity Q of less than 0.2, wherein the reactivity Q is defined as Alfred-Price. Price) and the amount of the at least one second cross-linking monomer is less than 0.8 mole percent of the total amount of ethylenically unsaturated monomers. Regarding expandable thermoplastic microspheres.

  The Alfred-Price Qe scheme as a method for quantifying monomer reactivity is well established in the polymer field and is described in Robert Z. Greenley, Polymer Handbook, 4th edition, Brandrup, Immergut and Gulke, John Wiley & Sons, New York, NY, (1999) pages 309-319. In the Qe scheme, Q represents the reactivity of the monomer and e represents the polarity of the monomer. A high value of Q indicates that the reactivity of the monomer is relatively high, and a low value of Q indicates that the reactivity of the monomer is relatively low. In the above document, the Q values for several types of monomers are clearly listed, and in the case of monomers not listed, the Q value can be estimated based on the values for similar monomers.

  Preferably, the at least one first crosslinking monomer has a reactivity Q of greater than 0.2 to 10 or 0.4 to 2. The at least one second crosslinking monomer preferably has a reactivity Q of less than 0.001 to 0.2, or 0.002 to 0.15.

  The amount of the at least one first crosslinking monomer, i.e. the crosslinking monomer having high reactivity, is preferably 0.01-1.0 mol% or 0.03-0.4% of the total amount of ethylenically unsaturated monomer. Mol%. The at least one first cross-linking monomer may be a mixture of two or more monomers having high reactivity. The amount of the at least one second crosslinking monomer, i.e. the crosslinking monomer having low reactivity, is preferably 0.01-0.75 mol% or 0.03-0.6 of the total amount of ethylenically unsaturated monomer. Mol%. The at least one second crosslinking monomer may be a mixture of two or more monomers having low reactivity. The total amount of the first and second crosslinking monomers is preferably 0.02-1.75 mol% or 0.06-1.0 mol% of the total amount of ethylenically unsaturated monomer. The first and second cross-linking monomers are usually preferably two or three carbon-carbon double bonds, but can have two, three, four or more carbon-carbon double bonds. .

  Vinyls such as (meth) acrylic acid esters or (meth) acrylamides or vinyl aromatic monomers having two or more carbon-carbon double bonds as useful crosslinking monomers with high reactivity (Q> 0.2) Monomer. It should be understood that whenever a chemical name includes “(meth) acryl” herein, “(meth) acryl” refers to both “methacryl” and “acryl”.

  Examples of preferred crosslinking monomers having high reactivity include trimethylolpropane tri (meth) acrylate, ethylene glycol di (meth) acrylate, di (ethylene glycol) di (meth) acrylate, 1,4-butanediol di (meth) Acrylate, di (trimethylolpropane) tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate and tris [ And (meth) acrylate derivatives such as 2-acryloyloxy) ethyl] isocyanurate. Particularly preferred are trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, di (ethylene glycol) dimethacrylate, 1,4-butanediol dimethacrylate, di (trimethylolpropane) tetramethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate. Derivatives of methacrylates such as methacrylate, dipentaerythritol pentamethacrylate, and dipentaerythritol hexamethacrylate.

  Other examples of useful crosslinking monomers with high reactivity include tri (ethylene glycol) di (meth) acrylate, tetra (ethylene glycol) di (meth) acrylate, poly (ethylene glycol) di (meth) acrylate, PEG # 200 di (meth) acrylate, PEG # 400 di (meth) acrylate, PEG # 600 di (meth) acrylate, propylene glycol di (meth) acrylate, di (propylene glycol) di (meth) acrylate, tri (propylene glycol) di (Meth) acrylate, tetra (propylene glycol) di (meth) acrylate, poly (propylene glycol) di (meth) acrylate, 1,3-propanediol di (meth) acrylate, 1,3-butanediol di (meth) acrylate ,bird Butanediol) di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,8-octanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decane Diol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 3-methyl-1,5-pentanediol di (meth) acrylate, 2,4-diethyl-1,5-pentanediol di (meth) acrylate, Glycerin di (meth) acrylate, glycerin tri (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, triacryl formal, divinylbenzene, divinyltoluene, divinylnaphthalene, N, N'-ethylenebisacrylamide Can be mentioned.

Further examples of highly reactive crosslinking monomers include alkyl ether diol di (meth) acrylates such as 3-oxo-1,6-hexanediol di (meth) acrylate (from aliphatic carbons R ₁ , R ₂ and ether linkages). The formula (represented by —R ₁ —O—R 2 —)) and alkyl ester diol di (meth) acrylates (aliphatic carbon R ₁ , R) such as hydroxypivalic acid neopentyl glycol di (meth) acrylate ₂ and an ester bond (represented by -R1-COO-R2-)).

  Two or more allylic double bonds, vinyl ether double bonds, vinyl silane double bonds, or non-conjugated olefinic double bonds, as useful crosslinking monomers with low reactivity (Q less than 0.2), or Mention may be made of monomers having other types of carbon-carbon double bonds having low reactivity. Examples of crosslinking monomers having low reactivity are ethylene glycol, propylene glycol, di-, tri-, tetra- or poly-ethylene glycol and propylene glycol, glycerin, butanediol, erythritol, pentaerythritol, dipentaerythritol, hexanediol , Octanediol, cyclohexanediol, cyclohexanetriol, xylitol, sorbitol, mannitol, glucose, sucrose, cellulose, hydroxylcellulose, methylcellulose and resorcinol polyvinyl or polyallyl ether.

  Other examples of the crosslinking monomer having low reactivity include, for example, polyvinyl or polyallyl ester of polycarboxylic acid, carbonic acid, cyanuric acid and isocyanuric acid. Further examples include pentaerythritol diallyl ether, pentaerythritol triallyl ether, pentaerythritol tetraallyl ether, trimethylolpropane diallyl ether, trimethylolpropane triallyl ether, polyallyl sucrose, polyallyl glucose, p-diallyl ether bisphenol A, o -Diallyl ether bisphenol A, glyceryl diallyl ether and allyl ethers such as tetra (allyloxy) ethane. Further examples include triallyl cyanurate, triallyl isocyanurate, triallyl melamine, diallyl isocyanurate, diallyl isocyanurate n-propyl ester diallyl carbonate, di (ethylene glycol) diallyl dicarbonate, di- or tri-allyl trimesate, melitto Di- or triallyl acid, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, diallyl maleate, diallyl fumarate, diallyl succinate, diallyl malonate, diallyl malonate diethyl ester, diallyl malonate dimethyl ester, diallyl oxalate, Diallyl adipate, diallyl sebacate, diallyl tartrate, diallyl silicate, di- or tri-allyl tricarbarate, di- or tri-allyl citrate, phosphorus Di- or tri-allyl, diallyl chlorendate, allyl crotonate, diallyl monoethylene glycol citrate, 1,1'-diallyl-2,2'-bis-imidazoline, diallyl propylene urea, diallyl ethylene urea, diallyl urea, diallylthio Urea, methyldiallylamine, di- or tri-allylamine, N, N-diallylethanolamine, tetraallylethylenediamine, tartaric acid diallylamide, tetraallyl tin, diphenyl diallyl tin, diallyl formal, 5,5-diallyl barbituric acid, diallyl phenol And allyl monomers such as diallyloxybenzene, diallylbenzene and triallylbenzene. Further monomers include di (ethylene glycol) divinyl ether, tri (ethylene glycol) divinyl ether, tetra (ethylene glycol) divinyl ether, poly (ethylene glycol) divinyl ether, 1,4-butanediol divinyl ether, divinyl ether, cyclohexane- Di- or polyvinyl ethers such as 1,4-dimethanol divinyl ether, poly (ethylene glycol) divinyl ether, poly (propylene glycol) divinyl ether and poly (tetramethylene glycol) divinyl ether. Further monomers include di- or polyvinyls such as divinyl oxalate, divinyl malonate, divinyl succinate, divinyl glutamate, divinyl adipate, divinyl sebacate, divinyl maleate, divinyl fumarate, divinyl citraconic acid, divinyl tartrate and divinyl mesaconate. Examples include esters. Additional monomers include mixed compounds such as ethylene glycol vinyl allyl citrate and allyl vinyl maleate. Further monomers include trivinylcyclohexane, divinylcyclohexane, 1,4-pentadiene, 2-methyl-1,4-pentadiene, 3-methyl-1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 2 -Methyl-1,5-hexadiene, 3-methyl-1,5-hexadiene, 1,5-hexadiene-3,4-diol, 1,5-heptadiene, 2-methyl-1,6-heptadiene-3-ol 1,6-heptadiene, 1,6-heptadiene-4-ol, 1,7-octadiene, 7-methyl-1,6-octadiene, 1,8-nonadiene, 1,9-decadiene, 1,5,9 -Decatriene, 1,10-undecadiene, 1,11-dodecadiene, 1,13-tetradecadiene, 1,19-eicosadiene, Non-conjugated alkenes such as tonelene, 1,5-cyclooctadiene, dicyclopentadiene and 2,5-norbornadiene and the corresponding substituted monomers (carbonyl, nitrile or similar groups and carbon-carbon double bonds, or benzene, etc. 2 or more isolated double bonds which are not conjugated with an aromatic system). Further monomers include 1,3-divinyltetramethyldisiloxane, 1,3-diallyltetramethyldisiloxane, 1,3-dimethyl-1,1,3,3-tetravinyldisiloxane, 1,3-divinyl-1 , 3-Dimethyl-1,3-dichlorodisiloxane, 1,3-divinyl-1,3-diphenyl-1,3-dimethyldisiloxane, 1,3-divinyltetraethoxydisiloxane, pentavinylpentamethylcyclopentasiloxane 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, 2,4,6-trimethyl-2,4,6-trivinylcyclotrisiloxane, 1,3, 5-trivinyl-1,1,3,5,5-pentamethyltrisiloxane, diphenyldivinylsilane, dimethyldivinylsilane, Tiltrivinylsilane, tetravinylsilane, 1,3-divinyl-1,1,3,3-tetramethyldisilazane, 1,3-divinyl-1,3-diphenyl-1,3-dimethyldisilazane, diallyldimethylsilane, Examples include silicone compounds such as diallyldiphenylsilane, diallyloxydimethylsilane, methyltriallylsilane, phenyltriallylsilane, tetraallyloxysilane, tetraallylsilane, and triallylsilane. Further monomers include ethylene, propylene, butylene and analogs thereof, glycols, glycerin, pentaerythritol, di- or polyvinyl ethers of sorbitol; di- or polyallyl compounds such as compounds based on glycol, glycerin and analogs thereof; The group represented by the combination of a cyclic compound and a heterocyclic compound is mentioned. Additional monomers include divinyl propylene urea, divinyl ethylene urea and 3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5] undecane.

  Examples of preferred crosslinking monomers having low reactivity include triallyl cyanurate, trivinylcyclohexane, 1,4-butanediol divinyl ether, diallyl carbonate, pentaerythritol triallyl ether, trimethylolpropane diallyl ether and triallyl trimesate. .

  The main part of the ethylenically unsaturated monomer contains only one carbon-carbon double bond and will hereinafter be referred to as non-crosslinked monomer. The amount of such monomer is preferably 98 to 99.98 mol% or 99 to 99.94 mol% of the total amount of ethylenically unsaturated monomer.

  Non-crosslinking monomers include, for example, nitrile-containing monomers such as acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, fumaronitrile or crotononitrile; acrylic acid esters such as methyl acrylate and ethyl acrylate; methyl methacrylate, Methacrylic acid esters such as isobornyl methacrylate, ethyl methacrylate or hydroxyethyl methacrylate; vinyl halides such as vinyl chloride; vinylidene halides such as vinylidene chloride; vinyl pyridine; vinyl esters such as vinyl acetate; styrene, halogenated styrene or Styrenes such as α-methylstyrene; unsaturated carboxylic acid compounds such as acrylic acid, methacrylic acid and salts thereof; or acrylamide, methacrylic acid Other may be unsaturated monomers such as de or N- substituted maleimide. Any mixture of the above-mentioned monomers can also be used.

  Preferably, the non-crosslinking monomer is most preferably in a large amount, e.g. 50-100 mol% or 70-100 mol%, preferably 80-100 mol% or 95-100 mol% of the ethylenically unsaturated non-crosslinking monomer. % Containing nitrile-containing monomers.

  The nitrile-containing monomer is preferably primarily selected from one or more of acrylonitrile and methacrylonitrile. When other ethylenically unsaturated monomers are present, the monomers are preferably selected from one or more of acrylic esters or methacrylic esters or methacrylic acid. It is also most preferred to use only monomers that do not contain halogens.

The softening temperature of the polymer shell, usually corresponding to its glass transition temperature (T _g ), is preferably in the range of 50-250 ° C. or 100-200 ° C.

  Preferably, the polymer shell comprises about 50 to about 95% or about 60 to about 90% by weight of the total microspheres.

  The blowing agent is usually a liquid having a boiling point not higher than the softening temperature of the thermoplastic polymer shell, and is n-pentane, isopentane, neopentane, cyclopentane, cyclohexane, n-butane, isobutane, n-hexane, isohexane, neohexane. , N-heptane, isoheptane, n-octane, isooctane, isodecane, isododecane or mixtures thereof. Apart from these, petroleum ether; or other hydrocarbon species such as chlorinated or fluorinated hydrocarbons such as methyl chloride, methylene chloride, dichloroethane, dichloroethylene, trichloroethane, trichloroethylene, trichlorofluoromethane, perfluorohydrocarbons may be used. it can. Particularly preferred blowing agents comprise at least one isopentane, isooctane and isododecane.

  The boiling point of the atmospheric blowing agent can be in a wide range, preferably from about -20 to about 200 ° C, and most preferably from about -20 to about 150 ° C. It is particularly preferred that the blowing agent has a boiling point or boiling range, so that the temperature is greater than 50 ° C, more preferably greater than 60 ° C, most preferably greater than 70 ° C, but preferably not greater than about 150 ° C. It would be necessary to evaporate at least 50%, preferably at least 80% by weight of the blowing agent at normal pressure.

  In one embodiment, the blowing agent preferably comprises isooctane in an amount of, for example, at least 25 wt% or at least 50 wt%, preferably at least 60 wt% or at least 70 wt%, or perhaps even up to 85 wt%. Contains or substantially consists of isooctane. The blowing agent may be one or more of butane, pentane, hexane, heptane, petroleum distillate, isododecane or other liquids that provide the appropriate boiling range of the blowing agent, for example, up to 75% by weight or up to 50% overall. It may further comprise wt%, preferably up to 40 wt% or up to 30 wt% or up to 15 wt%. Particularly preferred hydrocarbons for use in combination with isooctane are isobutane, isopentane, isohexane, n-pentane, n-hexane, petroleum ether, isododecane and n-heptane. In one embodiment, the blowing agent comprises 85-99 wt% or 90-95 wt% isooctane and 1-15 or 5-10 wt% isopentane.

  The blowing agent comprises, for example, about 5 to about 50 weight percent or about 10 to about 40 weight percent of the microspheres.

  In addition to the polymer shell and blowing agent, the microspheres can further comprise materials added during its production, usually in an amount of about 1 to about 20% by weight, preferably about 2 to about 10% by weight. . Examples of such materials are silica, chalk, bentonite, colloidal clay, boron nitride, starch, gum agar, modified polysaccharides such as methylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, starch ether, starch esters, crosslinked polymers, polymer particles such as One or more of polyamide, polycarbonate, polyether, polyethylene, polypropylene, polystyrene, polyacrylate and / or one of metals such as Al, Ca, Mg, Ba, Fe, Zn, Ni and Mn, Ti or Multiple salts, oxides or hydroxides such as calcium phosphate, calcium carbonate, magnesium hydroxide, barium sulfate, calcium oxalate, titanium dioxide, and aluminum, iron, sub- Is one or more solid suspending agents, such as nickel hydroxide or manganese. When present, such solid suspensions are usually primarily present on the outer surface of the polymer shell. However, even if the suspending agent is added during the production of the microspheres, it will be washed away at a later stage, and therefore will be substantially absent from the final product.

Preferably, the microspheres of the composition have a relatively high T _onset and T _max . The T _onset is preferably 150-230 ° C, most preferably 180-200 ° C. The T _maximum is preferably 170-260 ° C, most preferably 200-240 ° C.

  The expandable microspheres preferably have a volume median diameter of 1 to 500 μm, more preferably 5 to 100 μm, and most preferably 10 to 50 μm.

  A further aspect of the invention relates to a method for producing the expandable thermoplastic microspheres described above. The method comprises obtaining microspheres comprising a polymer shell encapsulating said blowing agent by polymerizing said ethylenically unsaturated monomer in the presence of a blowing agent, preferably in an aqueous suspension. . With regard to the types and amounts of monomers and blowing agents, reference is made to the above description for expandable microspheres. The production can follow the same principles as described in the already mentioned patent publications.

  In one embodiment of the invention, the microspheres are produced in a batch process, and then the polymerization can be carried out in a reaction vessel as described below. For 100 parts of monomer phase (suitably including monomer and blowing agent, the proportion of which determines the proportion of monomer in the polymer shell and the amount of blowing agent in the final product), for example 0.1 One or more polymerization initiators in an amount of -5 parts, for example an aqueous phase in an amount of 100-800 parts, and one or more preferably solid colloids in an amount of 1-20 parts, for example. Suspensions are mixed and homogenized. The resulting droplet size of the monomer phase determines the size of the final expandable microspheres, for example, according to the principles described in US Pat. No. 3,615,972, which is similar to that using various suspending agents. It can be applied to all generation methods. The temperature is suitably maintained at 40-90 ° C, preferably 50-80 ° C, and the appropriate pH depends on the suspending agent used. Suspending agents are salts, oxides or hydroxides of metals such as Ca, Mg, Ba, Zn, Ni and Mn, such as calcium phosphate, calcium carbonate, magnesium hydroxide, barium sulfate, calcium oxalate, and zinc When selected from one or more of nickel, manganese or hydroxides, for example, preferably a high pH of 5 to 12, most preferably 6 to 10, is suitable. When the suspending agent is selected from starch, methylcellulose, hydroxypropylmethylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, gum agar, silica, colloidal clay, or aluminum or iron oxide or hydroxide, preferably 1-6 Most preferably, a low pH of 3-5 is suitable. Each of the above drugs has a variety of optimum pH depending on, for example, solubility data.

  In order to enhance the effect of the suspending agent, it is also possible to add small amounts, for example 0.001-1% by weight, of one or more accelerators. Such accelerators are typically organic materials such as water-soluble sulfonated polystyrene, alginate, carboxymethylcellulose, tetramethylammonium hydroxide or chloride, or water-soluble condensation products of diethanolamine and adipic acid, ethylene oxide, urea and formaldehyde. Water-soluble condensation products of, water-soluble composite resinous amine condensation products such as polyethyleneimine, polyvinyl alcohol, polyvinylpyrrolidone, polyvinylamine, amphoteric materials such as protein materials such as gelatin, glue, casein, albumin, glutin, Nonionic materials such as methoxycellulose, soaps, ionic materials usually classified as emulsifiers such as alkyl sulfates and sulfate sulfonates, and one of the long-chain quaternary ammonium compounds. It may be selected from a plurality.

  Conventional radical polymerization can be used and the initiator is suitably from one or more of organic peroxides such as dialkyl peroxides, diacyl peroxides, peroxyesters, peroxydicarbonates or azo compounds. Selected. Suitable initiators include dicetyl peroxydicarbonate, di (4-tert-butylcyclohexyl) peroxydicarbonate, dioctanoyl peroxide, dibenzoyl peroxide, dilauroyl peroxide, didecanoyl peroxide, tert-butyl peracetate Tert-butyl perlaurate, tert-butyl perbenzoate, tert-butyl hydroperoxide, cumene hydroperoxide, cumene ethyl peroxide, diisopropylhydroxydicarboxylate, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (isobutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), dimethyl 2,2′-azobis (2-methylpropionate), 2,2′-azobi [2-methyl-N-(2-hydroxyethyl) propionamide], and the like. It is also possible to initiate the polymerization using radiation such as high energy ionizing radiation.

  When the polymerization is essentially complete, the microspheres are usually obtained as aqueous slurries or dispersions, which can be used as is or are used for floor filtration, filter presses, leaves to obtain so-called wet cakes. It is dehydrated by any conventional means such as filtration, rotary filtration, belt filtration or centrifugation. However, it is also possible to dry the microspheres by any conventional means such as spray drying, shelf drying, tunnel drying, rotary drying, drum drying, air drying, turbo shelf drying, disk drying, or fluidized bed drying.

  If appropriate, the microspheres can be treated at any stage to reduce the amount of residual unreacted monomer, for example, by any of the procedures described previously in WO 2004/072160 or US Pat. No. 4,287,308. can do.

  The microspheres of the present invention are useful as expansion agents for various applications such as for thermoplastic materials, particularly for high-temperature molten thermoplastic materials.

  A particular aspect of the present invention relates to the use of the expandable microspheres described above in an expandable formulation comprising a thermoplastic polymer matrix and expandable microspheres. The formulation optionally further comprises one or more additives such as colorants, stabilizers, reinforcing agents and the like. Examples of intumescent formulations include moldable composite sheets and compounds for use in injection molding, extrusion molding, blow molding, rotational molding, thermoforming, and the like. The amount of expandable microspheres is preferably 0.5-15% by weight or 1-5% by weight. The polymer may be, for example, polypropylene, polystyrene, polyethylene, thermoplastic polyurethane, styrene-ethylene-butylene-styrene copolymer, styrene-butadiene-styrene copolymer, polyvinyl chloride, ethylene-vinyl acetate copolymer or another copolymer having similar melting point. Or a copolymer of

  The present invention also relates to the above expandable formulation comprising a thermoplastic polymer matrix, the above expandable microspheres and the above optional additional additives.

The present invention provides a thermoplastic polymer at a temperature above the polymer melting point but below the expansion temperature (T _onset ) of the microspheres at the above expansion microspheres and at the above temperature, and optional additional additives as described above. It further relates to a method for its preparation comprising a mixing step.

  The present invention will be further described in conjunction with the following examples, which should not be construed as limiting the scope of the invention. Unless otherwise indicated, all parts and percentages are parts by weight and percentages. The mole% of crosslinking monomer always refers to the mole% relative to the total amount of ethylenically unsaturated monomer.

The expansion properties of the microspheres were evaluated with a Mettler Toledo TMA / SDTA 841 ^e by using a heating rate of 20 ° C./min and a load of 0.06 N (net). T _start is the temperature at which expansion begins, T _maximum is the temperature at which maximum expansion is obtained, and TMA density is the density of microspheres at T _maximum .

  The pre-expansion resistance of certain microspheres with high expansion temperatures was evaluated with TMA by using the stepwise temperature profile described in Table 1. Temperature stages 1 and 2 are preheating stages where microspheres with good pre-expansion resistance should have no or very little expansion, and temperature stages 3 and 4 are highly expanded microspheres. The expansion stage that should be. Dmax (preliminary) and Dmax (expansion) are the maximum displacements of the specimen due to microsphere size changes during the preheating phase (stages 1 and 2) and the expansion stage (stages 3 and 4), respectively. In some cases, Dmax (preliminary) may be negative due to the initial contraction of the microspheres before expansion begins. The TMA curve is normalized to a microsphere sample amount of 0.70 mg.

Since the particle size and the amount of blowing agent affect the T _onset , all comparisons were performed on particles with essentially the same amount of blowing agent and similar particle sizes.

  The particle size and particle size distribution were determined by laser light scattering on a wet sample with a Malvern Mastersizer Hydro 2000 SM instrument. The particle diameter is represented by volume median diameter D (0.5).

  The amount of blowing agent was determined by thermobalance analysis (TGA) with a Mettler Toledo TGA / SDTA851e. All samples were dried prior to analysis to eliminate as much moisture as possible and residual monomer if present. The analysis was carried out under a nitrogen atmosphere, starting at 30 ° C. and using a heating rate of 20 ° C./min.

Example 1
The reaction mixture containing Mg (OH) ₂ stabilized organic drops in water was created by mixing the phases and stirring vigorously until the appropriate drop size was obtained. The aqueous dispersion contained 5.0 parts of Mg (OH) ₂ and 371 parts of water. The organic droplets contain 2.0 parts dilauroyl peroxide, 25 parts isooctane, 65 parts acrylonitrile, 35 parts methacrylonitrile, and 0.52 parts (0.09 mol%) trimethylolpropane trimethacrylate. It was out. The polymerization was carried out in a sealed stirred reactor at 62 ° C. for 20 hours. After cooling to room temperature, a sample of the obtained microsphere slurry was taken out and the particle size distribution was measured. After filtration, washing and drying, the particles were analyzed by TMA. The dry particles contained about 22% by weight of isooctane and the average particle size was about 37 μm. TMA results are shown in Tables 3 and 4.

Examples 2-10
Microspheres were prepared in a plurality of polymerization experiments carried out in the same manner as in Example 1 except for the crosslinking monomer added according to Table 3. The polymerization was carried out at 62 ° C. as described in Example 1. The analysis results can be seen in Tables 3 and 4.

In Table 3, it can be seen that T _initiation is significantly increased by combining two different types of cross-linking monomers, ie, highly reactive TMPTMA and less reactive TAC. Only TAC gives a high T _onset but very little expansion.

  Table 4 shows that both good pre-expansion resistance and good expansibility can be realized by using both TMPTMA and TAC as crosslinking monomers.

Examples 11-18
Microspheres were prepared in a plurality of polymerization experiments carried out in the same manner as in Example 1 except for the crosslinking monomer added according to Table 5. The polymerization was carried out at 62 ° C. as described in Example 1. The analysis results can be seen in Tables 5 and 6.

From Table 5, as exemplified in Table 3, an increase in T _initiation can be achieved by increasing the amount of TMPTMA or DEGDMA, both of which are highly reactive, unless a less reactive crosslinking monomer is also used. Seems to happen only in small quantities.

  As can be seen from Table 6 above, the pre-swell resistance is insufficient with microspheres containing only TMPTMA or DEGDMA as the crosslinking monomer at a concentration that is also comparable to the total amount of crosslinking monomer in Table 4. Microspheres containing concentrations that are too high or too low also have poor expansion during the expansion phase (lower Dmax).

Examples 19-21
Microspheres were prepared in a plurality of polymerization experiments carried out in the same manner as in Example 1 except for the crosslinking monomer added according to Table 7. As a blowing agent, a mixture of 12.5 parts isopentane and 25.5 parts isooctane was used. The amounts of water and Mg (OH) _{2 in} the examples were 320 parts and 2.6 parts, respectively. The polymerization was carried out at 62 ° C. as described in Example 1. The analysis results can be found in Table 7.

In Table 7, it can be understood that, even when a mixture of isopentane and isooctane is used as a foaming agent, the T- _start increases as the amount of TAC increases.

Examples 22-33
Microspheres were prepared in a plurality of polymerization experiments carried out in the same manner as in Example 1 except for the crosslinking monomer and the blowing agent added according to Table 8. The blowing agents used in the examples were isopentane (IP), isooctane (IO), and isododecane (ID). The polymerization was carried out at 62 ° C. as described in Example 1. The analysis results can be found in Table 8.

In Table 8, it can be seen that TAC in combination with TMPTMA increases the T- _onset of microspheres containing various hydrocarbon mixtures as blowing agents. When using a blowing agent having a higher boiling point, the effect on T _initiation is more pronounced.

Examples 34-57
Microspheres were prepared in a plurality of polymerization experiments carried out in the same manner as in Example 1 except for the crosslinking monomer added according to Table 9. The amounts of water and Mg (OH) _{2 in} the examples were 323 to 371 parts and 2.1 to 5.0 parts, respectively. This is because the blending in different polymerization reactors is slightly different, but does not affect the thermal properties of the polymerized particles. The polymerization was carried out at 62 ° C. as described in Example 1. The analysis results can be known from Tables 9 and 10.

Tables 9 and 10 show the results for different crosslinking monomer combinations. Only when a highly reactive crosslinking monomer is combined with a less reactive crosslinking monomer, both high expansion and high pre-expansion resistance can be realized. In Examples 41 and 44, the value for T- _onset was lower than expected (see Table 9) because of the low degree of expansion performed at this relatively low temperature. This is probably due to the fact that the microspheres in these examples are relatively large in particle size and in such an analysis the larger particle fraction expands to some extent at lower temperatures. However, the resistance to pre-expansion is still very good, which can be seen in Table 10. In Examples 56 and 57, when two highly reactive crosslinking monomers are combined, the pre-expansion resistance is insufficient.

The present invention may include the following aspects.
[1] A thermally expandable thermoplastic microsphere comprising a polymer shell prepared from an ethylenically unsaturated monomer encapsulated with a blowing agent, wherein the ethylenically unsaturated monomer comprises two or more carbon-carbon dimers. At least one first crosslinking monomer having a heavy bond and at least one second crosslinking monomer having two or more carbon-carbon double bonds, wherein the at least one first crosslinking monomer is 0. Having a reactivity Q greater than 2 and the at least one second cross-linking monomer has a reactivity Q of less than 0.2, the reactivity Q being an Alfred-Price cue-e (Qe) Thermally expandable thermoplastic microspheres, defined according to the scheme, wherein the amount of said at least one second crosslinking monomer is less than 0.8 mol% of the total amount of ethylenically unsaturated monomers.
[2] The microsphere according to [1], wherein the at least one first crosslinking monomer has a reactivity Q of more than 0.2 to 10.
[3] The microsphere according to any one of [1] to [2], wherein the at least one second crosslinking monomer has a reactivity Q of 0.001 to less than 0.2.
[4] The above [1] to [3], wherein the amount of the at least one first crosslinking monomer is 0.01 to 1.0 mol% of the total amount of the ethylenically unsaturated monomer. The described microsphere.
[5] The above [1] to [4], wherein the amount of the at least one second crosslinking monomer is 0.01 to 0.75 mol% of the total amount of the ethylenically unsaturated monomer. The described microsphere.
[6] The above [1] to [5], wherein the at least one first crosslinking monomer is selected from the group consisting of one or more of (meth) acrylic acid ester or (meth) acrylamide or vinyl aromatic monomer. ] The microsphere as described in any one of.
[7] The at least one first crosslinking monomer is trimethylolpropane tri (meth) acrylate, ethylene glycol di (meth) acrylate, di (ethylene glycol) di (meth) acrylate, 1,4-butanediol di ( (Meth) acrylate, di (trimethylolpropane) tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate and The microsphere according to [6] above, which is one or more of tris [2-acryloyloxy) ethyl] isocyanurate.
[8] The at least one second crosslinking monomer is selected from the group consisting of monomers having two or more allylic double bonds, vinyl ether double bonds, vinylsilane double bonds, or nonconjugated olefinic double bonds. The microsphere according to any one of [1] to [7] above.
[9] The at least one second crosslinking monomer is triallyl cyanurate, trivinylcyclohexane, 1,4-butanediol divinyl ether, diallyl carbonate, pentaerythritol triallyl ether, trimethylolpropane diallyl ether and triallyl trimesate. The microsphere according to any one of [8], which is one or more.
[10] The above [1] to [9], wherein the ethylenically unsaturated monomer includes a non-crosslinked monomer in an amount of 98 to 99.98 mol% of the total amount of the ethylenically unsaturated monomer. Microspheres.
[11] The microsphere according to [10], wherein the non-crosslinking monomer includes a nitrile-containing monomer in an amount of 80 to 100 mol% of the ethylenically unsaturated non-crosslinking monomer.
[12] The microsphere according to any one of [1] to [11], wherein the foaming agent contains isooctane.
[13] The microsphere according to any one of [1] to [12] above, wherein the T _start of the thermally expandable microsphere is 150 to 230 ° C.
[14] A step of obtaining a microsphere including a polymer shell encapsulating the foaming agent by polymerizing the ethylenically unsaturated monomer in the presence of the foaming agent, wherein the ethylenically unsaturated monomer includes two or more At least one first cross-linking monomer having a carbon-carbon double bond and at least one second cross-linking monomer having two or more carbon-carbon double bonds, the at least one first The crosslinking monomer has a reactivity Q of greater than 0.2, and the at least one second crosslinking monomer has a reactivity Q of less than 0.2, and the reactivity Q is defined as Alfred-Price. ) And the amount of the at least one second crosslinking monomer is less than 0.8 mol% of the total amount of ethylenically unsaturated monomers. Comprising, methods for producing heat-expandable microspheres according to any one of [13] from the [1].
[15] Use of the thermally expandable microsphere according to any one of [1] to [13] above in an expandable formulation comprising a thermoplastic polymer matrix and expandable microspheres.
[16] An expandable composition comprising the thermoplastic polymer matrix and expandable microspheres according to any one of [1] to [13] above.
[17] A step of mixing the thermoplastic polymer and the expandable microspheres according to any one of [1] to [13] above at a temperature higher than the melting point of the polymer but lower than the expansion temperature of the microspheres. A method for preparing an expandable formulation as described in [14] above.

Claims (13)

  A thermally expandable thermoplastic microsphere comprising a polymer shell prepared from an ethylenically unsaturated monomer encapsulated with a blowing agent, wherein the ethylenically unsaturated monomer has two or more carbon-carbon double bonds. At least one first cross-linking monomer having and at least one second cross-linking monomer having two or more carbon-carbon double bonds, wherein the at least one first cross-linking monomer is greater than 0.2. And having at least one second cross-linking monomer having a reactivity Q of less than 0.2, the reactivity Q being an Alfred-Price Q-E (Q- e) defined according to the scheme, wherein the at least one first crosslinking monomer is trimethylolpropane tri (meth) acrylate, ethylene glycol di (meth) acrylate , Di (ethylene glycol) di (meth) acrylate, 1,4-butanediol di (meth) acrylate, di (trimethylolpropane) tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) One or more of acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate and tris [2-acryloyloxy) ethyl] isocyanurate, wherein the at least one second crosslinking monomer is Triallyl cyanurate, trivinylcyclohexane, 1,4-butanediol divinyl ether, diallyl carbonate, pentaerythritol triallyl ether, trimethylolpropane diallyl ether and trimer Is one or more phosphate triallyl said thermally expandable thermoplastic microspheres amount of at least one second crosslinking monomer is less than 0.8 mol% of the total amount of ethylenically unsaturated monomers.   The microsphere of claim 1, wherein the at least one first crosslinking monomer has a reactivity Q of greater than 0.2 to 10.   3. The microsphere according to claim 1, wherein the at least one second crosslinking monomer has a reactivity Q of less than 0.001 to 0.2.   The microsphere according to any one of claims 1 to 3, wherein the amount of the at least one first crosslinking monomer is 0.01 to 1.0 mol% of the total amount of the ethylenically unsaturated monomer.   The microsphere according to any one of claims 1 to 4, wherein the amount of the at least one second crosslinking monomer is 0.01 to 0.75 mol% of the total amount of the ethylenically unsaturated monomer.   The microsphere according to any one of claims 1 to 5, wherein the ethylenically unsaturated monomer comprises non-crosslinked monomer in an amount of 98 to 99.98 mol% of the total amount of ethylenically unsaturated monomer.   The microsphere according to any one of claims 1 to 6, wherein the non-crosslinking monomer comprises a nitrile-containing monomer in an amount of 80 to 100 mol% of the ethylenically unsaturated non-crosslinking monomer.   The microsphere according to any one of claims 1 to 7, wherein the blowing agent comprises isooctane. T _start of the heat-expandable microspheres Ri 150 to 230 ° C. der, T _start is the temperature at which the expansion is initiated, the microspheres according to any one of claims 1 to 8.   Polymerizing an ethylenically unsaturated monomer in the presence of a blowing agent to obtain microspheres comprising a polymer shell encapsulating said blowing agent, wherein said ethylenically unsaturated monomer comprises two or more carbon- Comprising at least one first crosslinking monomer having a carbon double bond and at least one second crosslinking monomer having two or more carbon-carbon double bonds, wherein the at least one first crosslinking monomer is A reactivity Q greater than 0.2, wherein the at least one second cross-linking monomer has a reactivity Q of less than 0.2, the reactivity Q being an Alfred-Price cue -Defined according to the Q-e scheme, wherein the at least one first crosslinking monomer is trimethylolpropane tri (meth) acrylate, ethylene glycol Di (meth) acrylate, di (ethylene glycol) di (meth) acrylate, 1,4-butanediol di (meth) acrylate, di (trimethylolpropane) tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, penta One or more of erythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate and tris [2-acryloyloxy) ethyl] isocyanurate, the at least one second The crosslinking monomers are triallyl cyanurate, trivinylcyclohexane, 1,4-butanediol divinyl ether, diallyl carbonate, pentaerythritol triallyl ether, trimethylolpropane di 10. A step comprising one or more of ril ether and triallyl trimesate, wherein the amount of said at least one second crosslinking monomer is less than 0.8 mol% of the total amount of ethylenically unsaturated monomers. A method for producing thermally expandable microspheres according to any one of the above.   Use of thermally expandable microspheres according to any one of claims 1 to 9 in an expandable formulation comprising a thermoplastic polymer matrix and expandable microspheres. A thermoplastic polymer matrix, expandable formulation comprising a bulging tonicity microspheres according to any one of claims 1 to 9.   The method of claim 12, comprising mixing the thermoplastic polymer and the expandable microspheres according to any one of claims 1 to 9 at a temperature above the melting point of the polymer but below the expansion temperature of the microspheres. Process for preparing the expandable formulation described.