KR20010080903A - Process for Preparing a Polymeric Foam Using a Perfluorochemical Compound Dissolved or Dispersed in a Hydrofluoroether - Google Patents

Abstract

The present invention comprises evaporating a blowing agent composition comprising a perfluorocompound dissolved or dispersed in hydrofluoroether in the presence of at least one foamable composition and a precursor composition thereof, wherein the hydrofluoroether and perfluorocompound are Provided are methods of making polymeric foams that are liquid at atmospheric pressure and about 20 ° C. Also provided are blowing agent compositions and foamable compositions useful in such methods.

Description

Process for preparing a polymeric foam using a perfluorochemical compound dissolved or dispersed in a hydrofluoroether

According to "Cellular Materials," Encyclopedia of Polymer Science and Engineering, vol. 3, pages 1-59, (2d ed. John Wiley & Sons, 1985), foam plastics are arranged through their mass. It is defined as a plastic whose apparent density substantially decreases with the presence of various cells. The gas phase in the foamed plastic is generally distributed in the cell. The blowing agent forms, for example, the gas used to create the cells in the foamable polymeric material for making foam insulation. Physical blowing agents form cells by, for example, phase changes such as liquid volatilization or gas being dissolved in a polymer under high pressure. Low boiling liquids, in particular chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), are used on a large scale worldwide for the production of foam plastics. However, CFCs and HCFCs are associated with the destruction of the earth's protective ozone layer. See Encyclopedia, vol. 2, page 437.

Commercially important liquid blowing agents are aliphatic hydrocarbons and their chloro- and fluoro-derivatives. For example, isomers of pentane, hexane and heptane are mainly used in the production of very low density polystyrene foam. These liquids tend to be cheaper and less toxic, but are highly flammable. See Encyclopedia, vol. 2, page 434.

The production of cellular polyurethane products such as cellular polyurethane elastomers and flexible, semi-solid or solid polyurethane foams in the presence of catalysts, blowing agents, processing aids or additives has been described in numerous patents and documents.

For an overview of the preparation of cellular polyurethane elastomers, polyurethane foams and polyisocyanurate foams, their mechanical properties and their use, see, for example, High Polymers, Vol. 14, "Polyurethanes," Parts I and II by JHSaunders. and KCFrisch (Interscience Publishers, New York 1962 and 1964), Plastic Handbook, Volume VII, "Polyurethanes," 1st ed. 1966, published by R. Vieweg and A. Hochtlen and 2d ed. 1983, published by G. Oertel (Carl Hanser Verlag, Munich) and "Integral Foams," published by H. Piechota and H. Rohr (Carl Hanser Verlag, Munich, 1975).

Substantially two types of blowing agents are used to prepare cellular polyurethanes: (1) alkanes such as butane, n-pentane or cyclopentane, methylene chloride, dichloromonofluoromethane and trichlorofluoro Low boiling inert liquids that evaporate under the influence of exothermic polymerization reaction processes, such as halogenated hydrocarbons such as romethane or halogenated fluorocarbons; And (2) chemical compounds that form gaseous blowing agents by chemical reaction or thermal decomposition, such as isocyanate groups that react with water to produce carbon dioxide.

U.S. Patent 4,972,002 discloses (a) organic and / or modified organic polyisocyanates and (b) one or more high molecular weight compounds having two or more reactive hydrogen atoms and optionally (c) low molecular weight chain extenders and / or ) Producing a cellular plastic by polyisocyanate polyaddition process by reacting the crosslinking agent in the presence of (d) blowing agent, (e) catalyst, (f) additive and / or processing aid, wherein the blowing agent comprises 3 to 8 Low boiling point fluorinated aliphatic and / or cycloaliphatic hydrocarbons having carbon number). In accordance with the teachings of this patent, a homogeneous fine cell structure is obtained by suitably emulsifying the blowing agent insoluble or very little soluble in the reaction mixture. However, the cost of this type of blowing agent is a serious disadvantage.

U.S. Patent 5,290,823 discloses a blowing agent mixture for use in the manufacture of solid polyurethane foams. This mixture comprises 5 to 40% by weight of highly fluorinated or perfluorinated compounds, 30 to 95% by weight of cyclopentane and 0 to 45% by weight of additional aliphatic and / or cycloaliphatic hydrocarbons having 4 to 8 carbon atoms. Compound. Because the substantial amount of fluorinated blowing agent is substituted with cyclopentane and other hydrocarbon blowing agents, this blowing agent is less expensive than the blowing agent mixture disclosed in US Pat. No. 4,972,002. The patent also teaches that the fluorinated blowing agent is slightly soluble or insoluble in the reactive mixture as key to obtaining the fine cell structure. Poor solubility, although effective in the production of desirable foams, also provides disadvantages in the production of foams. For example, the resulting foamed emulsions are low in stability and require constant and vigorous stirring to maintain the emulsion. In addition, the fluorinated blowing agent cannot be readily dissolved in the cyclopentane blowing agent so that both blowing agents need to be stored separately before being used in the foam formation process.

US Pat. No. 4,981,879 describes a process for making cellular polymers having urethane groups, isocyanurate groups, or both. These cellular polymers typically have a boiling point by reacting organic polyisocyanates with polyols in the presence of a blowing agent such as hydrocarbons, hydrochlorofluorocarbons or chlorofluorocarbons, a catalyst and a mixture of perfluorinated or perfluorinated hydrocarbons. Lower perfluorinated hydrocarbons are made by acting as co-blowing agents. According to this US patent, the size is reduced by the perfluorocompound additive and the initial k-factor is improved compared to foams produced without the perfluorocompound additive.

The use of unsaturated perfluorocompounds as blowing agents or co-foaming agents is described in US Pat. No. 5,539,008. The use of unsaturated perfluorocompounds as co-foaming agents is said to be desirable given the cost and availability. Common blowing agents disclosed for use with unsaturated perfluorocompound blowing agents include hydrocarbons such as pentane and cyclopentane.

U.S. Patent 5,210,106 discloses a mixture of one or more low boiling hydrochlorofluorocarbons and / or one or more hydrofluorocarbons and one or more low boiling point chlorine free fluorinated compounds as blowing agents; A blowing agent emulsion comprising a fluorochemical surfactant and a continuous organic phase is disclosed.

US Pat. No. 5,162,384 discloses one or more low boiling point, perfluorinated, N-aliphatic, cyclic 1,3- or 1,4-aminoethers for use in the foamable polymerizable reaction mixture for making foam plastics. A foaming agent emulsion comprising a blowing agent is disclosed.

US 4,997,706 discloses the use of C _2-6 polyfluorocarbon compounds that do not contain chlorine or bromine atoms as physical blowing agents in the manufacture of solid, closed cells, polymer foams. It is disclosed that the thermal insulation of the polyurethane foams produced with such blowing agents can substantially reduce the loss over time.

The present invention relates to a process for producing polymeric foams using perfluorine compounds as blowing agents. The invention also relates to foamable compositions and blowing agent compositions comprising perfluorocompounds and hydrofluoroethers.

Summary of the Invention

The present invention provides a method of making a polymeric foam comprising evaporating a blowing agent composition comprising a perfluorocompound dissolved or dispersed in hydrofluoroether in the presence of at least one foamable polymer or precursor composition thereof. The hydrofluoroether and perfluorocompound are liquid at atmospheric pressure and about 20 ° C. and mixtures of perfluorocompound and hydrofluoroether can be used in the present invention. Preferably, the blowing agent composition also contains one or more co-blowing agents other than the perfluorocompound or hydrofluoroether.

One advantage of the present invention is that the blowing agent composition is more stable (ie no phase separation) since hydrofluoroether substantially increases the solubility of the perfluorocompound in the co-blowing agent. Moreover, the solubility of the foaming agent composition in a foamable polymer or its precursor composition improves. Nevertheless, despite the improved solubility of perfluorocompounds, the foams (and especially rigid polyurethane foams) produced according to the invention show uniform, fine cells and good thermal insulation.

The present invention also provides a homogeneous blowing agent composition comprising a perfluorocompound, a hydrofluoroether and a co-foaming agent other than the perfluorocompound, wherein the hydrofluoroether and the perfluorocompound are liquid at 20 ° C. atmospheric pressure.

The present invention also provides a foamable composition comprising a foamable polymer or precursor composition thereof and a foaming agent composition.

<Detailed Description of the Invention>

The blowing agent composition of the present invention comprises a perfluoro compound dissolved or dispersed in hydrofluoroether. In the present invention, the polymer foam is produced by evaporating the perfluorocompound in the presence of the expandable polymer or precursor composition thereof. Typically, perfluorine compounds are used in amounts of about 0.05 to about 2.5 weight percent of the total foamable composition. The amount of hydrofluoroether will generally be sufficient to dissolve or disperse all perfluorocompounds to make a hydrofluoroether mixture of perfluorocompounds and hydrofluoroethers.

Perfluorocompounds for use in the present invention preferably comprise saturated or unsaturated hydrocarbon compounds which are free of other halogens, such as chlorine or bromine, in particular they are perfluoroaliphatic compounds, perfluorocycloaliphatic compounds , Perfluoroolefin compounds, perfluorocycloolefin compounds, and perfluoroaliphatic, perfluorocycloaliphatic, perfluoroolefin or perfluorocyclo containing heteroatoms such as divalent oxygen, trivalent nitrogen and polyvalent sulfur Olefin compounds. Preferably, the perfluorine compound contains about 4 to about 12 carbon atoms. Specific examples thereof include perfluoroalkanes such as perfluorobutane, perfluoropentane, perfluorohexane, perfluoroheptane and perfluorooctane; Perfluorocycloalkanes such as perfluorocyclobutane, perfluorodimethylcyclobutane, perfluoromethylcyclopentane; Perfluoroethers such as perfluoro-2-butyl-tetrahydrofuran; Formal, such as perfluoro-3,5-dioxaheptane; Perfluoroamines such as perfluorotriethylamine, perfluorotripropylamine, perfluorotributylamine, perfluoro-N-methyl pyrrolidine; Perfluoroamino ethers such as perfluoro-N-methyl morpholine; And perfluorinated sulfur compounds. Even more suitable perfluorine compounds include the perfluorinated heterocyclic compounds disclosed in US Pat. No. 5,162,384. Examples of perfluoroolefin compounds and perfluorocycloolefin compounds include hexafluoropropene dimers (eg perfluoro (4-methylpent-2-ene) and perfluoro (2-methylpent-2- yen)); Hexafluoropropane trimers (eg perfluoro (4-methyl-3-isopropylpent-2-ene) and perfluoro (2,4-dimethyl-3-ethylpent-2-ene)); Tetrafluoroethylene oligomers (e.g. perfluoro (3-methylpent-2-ene), perfluoro (3,4-dimethylhex-3-ene) and perfluoro (2,4-dimethyl-4- Ethylhex-2-ene)); Perfluoro (1-pentene); Perfluoro (2-pentene); Perfluoro (1-hexene); Perfluoro (2-hexene); Perfluoro (3-hexene); Perfluoro (1-heptene); Perfluoro (2-heptene); Perfluoro (3-heptene); Hexafluorobenzene; Octafluorotoluene; Decafluoro-o-xylene; Decafluoro-m-xylene; Decafluoro-p-xylene; Perfluorocyclopentene; Isomers of C ₆ F ₁₀ (eg perfluorocyclohexene, perfluoro (1-methylcyclopentene), perfluoro (3-methylcyclopentene) and perfluoro (4-methylcyclopentene)); Perfluoro (1-methylcyclohexene); Perfluoro (3-methylcyclohexene); Perfluoro (4-methylcyclohexene); Perfluoro (oxaalkene) (eg perfluoro (3-oxahex-1-ene), perfluoro (3-oxahept-1-ene) and perfluoro (3-oxa-4-methylpent -1-ene)); And perfluoro (3-ethyl-3-azapent-1-ene).

Even more suitable perfluorinated compounds for use in the present invention include perfluorinated ketones. Preferably the perfluorinated ketones are generally liquid, ie liquid at 20 ° C. and atmospheric pressure, examples of such ketones include perfluorinated aliphatic ketones having at least about 4 carbon atoms. Preferably, the boiling point of the perfluorinated ketone is between about 20 ° C and about 120 ° C. Very preferred perfluorinated ketones for use in the present invention have the formula (I)

Wherein R _f ¹ and R _f ² each independently represent a fluorinated aliphatic group, Q represents a fluorinated alkylene group or a bond, and n represents 0 or 1. Preferably, at least one of R _f ¹ , R _f ² and Q is perfluorinated, most preferably all three are perfluorinated.

Specific examples of perfluorinated ketones useful in the present invention include the following.

C ₂ F ₅ COCF (CF ₃ ) ₂

C ₂ F ₅ COCF ₃

(CF ₃ ) ₂ CFCOCF (CF ₃ ) ₂

CF ₃ COCF ₂ COCF ₃

Preferably, the hydrofluoroethers, ie partially fluorinated ethers, comprise perfluorinated aliphatic groups bonded to hydrocarbon groups by oxygen atoms. Perfluoroaliphatic groups may contain one or more chain heteroatoms such as oxygen, nitrogen or sulfur, although oxygen and nitrogen are preferred if present. More preferably, the perfluoroaliphatic moiety contains 2 to about 10 carbon atoms, and may optionally contain oxygen and / or nitrogen chain heteroatoms, and the alkyl moiety comprises 1 to about 4 carbon atoms. do.

Particularly preferred fluorinated ethers have the formula:

(R _h -O) _x -R _f

Where

x is 1 or 2,

R _h represents an alkyl group having 1 to about 4 carbon atoms,

R _f represents a perfluorinated aliphatic group comprising at least two carbon atoms, preferably between 2 and about 9 carbon atoms, and any chain heteroatoms such as oxygen, nitrogen and sulfur atoms.

When x is 1, R _f is preferably a linear or branched perfluoroalkyl group, a perfluorocycloalkyl group containing a perfluoroalkyl group, a perfluorocycloalkyl group, linear or branched with one or more chain heteroatoms It is selected from the group consisting of a chain perfluoroalkyl group, a perfluorocycloalkyl group containing a perfluoroalkyl group having at least one chain heteroatom and a perfluorocycloalkyl group having at least one chain heteroatom. Particularly preferred chain heteroatoms include oxygen or nitrogen atoms.

When x is 2, R _f preferably has a linear or branched perfluoroalkylene group, a perfluorocycloalkyl group containing a perfluoroalkylene group, a perfluorocycloalkylene group, at least one chain heteroatom Selected from the group consisting of linear or branched perfluoroalkylene groups, perfluorocycloalkyl groups containing perfluoroalkylene groups having at least one chain heteroatom, and perfluorocycloalkylene groups having at least one chain heteroatom . Particularly preferred heteroatoms include oxygen or nitrogen atoms.

Most preferably, x is 1, hydrofluoroethers are usually liquid, and R _f is a linear or branched perfluoroalkyl group having 3 to about 9 carbon atoms, perfluorocycloalkyl having 5 to about 7 carbon atoms. -A perfluoroalkyl group and a perfluorocycloalkyl group having 5 to about 6 carbon atoms; R _h is a methyl or ethyl group; R _f may contain one or more chain heteroatoms; The sum of the number of carbon atoms in R _f and the number of carbon atoms in R _h is about 4 or more.

Representative examples of hydrofluoroethers suitable for use in the methods and compositions of the present invention include the following compounds:

nC ₄ F ₉ OCH ₃ , nC ₄ F ₉ OCH ₂ CH ₃ , CF ₃ CF (CF ₃ ) CF ₂ OCH ₃ , CF ₃ CF (CF ₃ ) CF ₂ OC ₂ H ₅ , C ₈ F ₁₇ OCH ₃ , CH ₃ O- (CF ₂ ) ₄ -OCH ₃ , C ₅ F ₁₁ OC ₂ H ₅ , C ₃ F ₇ OCH ₃ , CF ₃ OC ₂ F ₄ OC ₂ H ₅ , C ₃ F ₇ OCF (CF ₃ ) CF ₂ OCH ₃ , (CF ₃ ) ₂ CFOCH ₃ , (CF ₃ ) ₃ COCH ₃ , C ₄ F ₉ 0C ₂ F ₄ OC ₂ F ₄ OC ₂ H ₅ , C ₄ F ₉ 0 (CF ₂ ) ₃ OCH ₃ ,

And 1,1-dimethoxyperfluorocyclohexane.

In a particularly preferred embodiment of the present invention, the blowing agent composition further comprises a co-blowing agent other than a perfluorocompound. Although perfluorocompounds can be effective blowing agents or expensive, it may be advantageous to introduce another less expensive blowing agent in the blowing agent composition. Such compositions can be optimized in terms of cost and performance. In this preferred embodiment, hydrofluoroethers can increase the suitability of perfluorocompounds and co-foaming agents. Examples of useful co-blowing agents include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), hydrochlorocarbons (HCCs), iodofluorocarbons (IFCs) and hydrocarbons can do. Co-foaming agents for use in the present invention should have a boiling point of about -45 ° C to about 100 ° C at atmospheric pressure. Preferably at atmospheric pressure the co-foaming agent has a boiling point of at least about 20 ° C, more preferably between about 20 ° C and about 100 ° C, most preferably between about 30 ° C and about 65 ° C.

Examples of co-foaming agents usable in the present invention include aliphatic and cycloaliphatic hydrocarbons of about 5 to about 7 carbon atoms, such as n-pentane and cyclopentane, CFCl ₃ (CFC-11) and CCl ₂ FCClF ₂ (CFC-113); Same CFC, CF ₃ CF ₂ CHFCHFCF ₃ , CF ₃ CH ₂ CF ₂ H, CF ₃ CH ₂ CF ₂ CH ₃ , CF ₃ CF ₂ H, CH ₃ CF ₂ H (HFC-152a), CF ₃ CH ₂ CH ₂ HFC such as CF ₃ and CHF ₂ CF ₂ CH ₂ F, HCFC such as CH ₃ CCl ₂ F, CF ₃ CHCl ₂ and CF ₂ HCl, HCC such as 2-chloropropane and IFC such as CF ₃ I.

Preferred blowing agent compositions of the present invention comprise (by weight) between about 5 and about 50 parts of co-blowing agent, between about 0.5 and about 10 parts of perfluorocompound and between about 0.1 and about 5 parts of hydrofluoroether.

Suitable foamable polymers for use in the foamable compositions of the present invention include polyolefins (eg polystyrene, poly (vinyl chloride) and polyethylene). Foams can be prepared from styrene polymers using conventional extrusion methods. The blowing agent composition may be injected into a stream of heat-plasticized styrene polymer in an extruder, admixed and then extruded to form a foam. Representative examples of suitable styrene polymers include styrene solid homopolymers, α-methylstyrene, ring-alkylated styrenes and ring-halogenated styrenes, and other olefin monomers that are readily copolymerizable with these monomers (eg methyl methacrylate, acrylonitrile). , Maleic anhydride, citraconic anhydride, itaconic anhydride, acrylic acid, N-vinylcarbazole, butadiene and divinylbenzene). Suitable vinyl chloride polymers include vinyl chloride homopolymers and copolymers of vinyl chloride and other vinyl monomers. Also useful are ethylene homopolymers and copolymers of ethylene with, for example, 2-butene, acrylic acid, propylene or butadiene. Mixtures of different types of polymers can be used.

Precursors of foamable polymers suitable for use in the foamable compositions of the present invention include precursors of phenolic polymers, silicone polymers and isocyanate-based polymers (e.g. polyurethanes, polyisocyanurates, polyureas, polycarbodiimides and polyimides). It includes. Preferred are the precursors of isocyanate-based polymers, because the blowing agent compositions of the present invention are particularly useful in producing polyurethane or polyisocyanurate foams. Accordingly, preferred foamable compositions of the present invention comprise (a) a perfluorocompound dissolved or dispersed in hydrofluoroether, (b) at least one organic polyisocyanate, and (c) at least one compound containing at least two reactive hydrogen atoms. Include. Most preferably, the foamable composition further comprises one or more co-expanding agents.

Suitable polyisocyanates for use in the preferred compositions of the present invention include aliphatic, alicyclic, arylaliphatic, aromatic or heterocyclic polyisocyanates or mixtures thereof. Any polyisocyanate suitable for use in preparing polymeric foams can be used. Of particular importance are aromatic diisocyanates such as toluene and diphenylmethane diisocyanate, in pure, modified or crude form. MDI variants (diphenylmethane diisocyanate modified by introduction of urethane, allophanate, urea, biuret, carbodiimide, uretonimine or isocyanurate residues), and diphenylmethane diisocyanate and in the art Particularly useful are mixtures of these oligomers, known as crude or polymeric MDI (polymethylene polyphenylene polyisocyanate).

Representative examples of suitable polyisocyanates include ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, trimethyl hexamethylene diisocyanate, 1,12-dodecane diisocyanate, cyclobutane-1,3 -Diisocyanate, cyclohexane-1,3- and -1,4-diisocyanate (and mixtures of these isomers), diisocyanato-3,3,5-trimethyl-5-isocyanatomethyl cyclohexane, 2,4- and 2,6-toluene diisocyanate (and mixtures of these isomers), diphenylmethane-2,4'- and / or -4,4'-diisocyanate, naphthalene-1,5-diisocyanate , Reaction products of four equivalents of the isocyanate-containing compounds with compounds containing two isocyanate-reactive groups, triphenylmethane-4,4 ', 4 "-triisocyanate, polymethylene polyphenylene polyisocyanate, m- and p-isocyanatophenyl sulfonyl isocyanates, perchlorated aryl polyisocyanates, polyisocyanates containing carbodiimide groups, norbornane diisocyanates, polyisocyanates containing allophanate groups, isocyanurate groups Polyisocyanate containing, polyisocyanate containing urethane group, polyisocyanate containing acrylated urea group, polyisocyanate containing biuret group, polyisocyanate produced by telomerization reaction, polyisocyanate containing ester group, said diisocyanate Diisocyanates with isocyanate groups (obtained in commercial production of isocyanates), including reaction products of acetals, polyisocyanates containing polymerizable fatty acid esters, and mixtures thereof. Can be used in solution in a single or in one or more of the aforementioned polyisocyanates.

Reactive hydrogen-containing compounds suitable for use in the preferred foamable compositions of the present invention contain two or more isocyanate-reactive hydrogen atoms, preferably in the form of hydroxyl, primary or secondary amines, carboxylic acid or thiol groups or combinations thereof. As, things are things. Polyols, ie compounds having two or more hydroxyl groups per molecule, are particularly preferred because of their desirable reactivity with polyisocyanates. Preferred polyols are those having from 2 to about 50, preferably from 2 to about 8, more preferably from 2 to about 4 hydroxyl groups. Such polyols are, for example, polyesters, polyethers, polythioethers, polyacetals, polycarbonates, polymethacrylates, polyester amides or hydroxyl-containing prepolymers of these compounds and polyisocyanates in amounts below stoichiometry Can be. Generally, the reactive hydrogen-containing compounds used in the preferred foamable compositions of the present invention have a weight average molecular weight of about 50 to about 50,000, preferably about 500 to about 25,000.

Representative examples of suitable reactive hydrogen-containing compounds are described, for example, in JHSaunders and KCFrisch, High Polymers, Volume XVI, "Polyurethanes," Part I, pages 32-54 and 65-88, Interscience, New York (1962) ]. Mixtures of these compounds are also useful and in certain cases it is particularly advantageous to mix low melting point and high melting point polyhydroxyl-containing compounds as described in German Patent No. 2,706,297 (Bayer AG). Useful polyols include ethylene glycol, 1,2- and 1,3-propylene glycol, 1,4- and 2,3-butylene glycol, 1,5-pentane diol, 1,6-hexane diol, 1,8- Octane diol, neopentyl glycol, 1,4-bis (hydroxymethyl) cyclohexane, 2-methyl-1,3-propane diol, dibromobutene diol, glycerol, trimethylolpropane, 1,2,6-hexane Triol, trimethylolethane, pentaerythritol, quinitol, mannitol, sorbitol, diethylene glycol, triethylene glycol, tetraethylene glycol, more polyethylene glycol, dipropylene glycol, more polypropylene glycol, dibutylene glycol, the Polybutylene glycol, 4,4'-dihydroxydiphenyl propane and dihydroxymethyl hydroquinone. Other suitable polyols include the condensation products of polybasic acids and polyols, such as polyethylene adipate and polycaprolactone-based polyols, and of the formaldehyde hydrate in the presence of metal compounds as catalysts and compounds capable of forming endodiols as cocatalysts And mixtures of hydroxy aldehydes and hydroxy ketones ("formos") and polyhydric alcohols ("formitols") obtained by reduction therefrom, formed during the autocondensation process (see, for example, US Pat. No. 4,341,909) Schneider et al., US Pat. No. 4,247,653 (Wagner), US Pat. No. 4,221,876 (Wagner), US Pat. No. 4,326,086 (Mohring et al.) And US Pat. No. 4,205,138 (Muller et al.), And Canadian Patent No. 1,088,523 ( Bayer AG). It is also possible to use solutions of polyisocyanate polyaddition products, in particular polyurethane urea solutions and / or polyhydrazodicarbonamide solutions containing ionic groups, in low molecular weight polyhydric alcohols (see German Patent No. 2,638,759).

As will be apparent to those skilled in the art of polyurethane science and engineering, many other compounds containing isocyanate-reactive hydrogen atoms are also useful in the preferred foamable compositions of the present invention.

Preferred polymer foams are evaporated (e.g., at least one blowing agent, typically liquid, in the presence of a perfluorocompound dissolved in hydrofluoroether, at least one organic polyisocyanate and at least one compound containing at least two reactive hydrogen atoms. Using the heat of the precursor reaction), a preferred foamable composition of the present invention can be used. Preferably, from about 100 to about 300 parts by weight of polyisocyanate (s) and from about 100 to about 150 parts by weight of reactive hydrogen-containing compound (s) of 1 to 10 parts by weight of perfluorocompound and 0.1 to 2 parts by weight of hydrofluoroether Used in combination with). More preferably, co-foaming agents are also used in amounts of from 5 to 50 parts by weight. In preparing polyisocyanate-based foams, polyisocyanates, reactive hydrogen-containing compounds and blowing agent compositions are generally combined, thoroughly mixed (for example using any of a variety of known mixing heads and spraying devices). Swelling to cure the cellular polymer. It is often not necessary, but often convenient, to premix certain components of the foamable composition prior to the reaction of the polyisocyanate and the reactive hydrogen-containing compound. For example, it is often useful to first combine the reactive hydrogen-containing compound, blowing agent composition and any other components (eg surfactant) other than polyisocyanate and then mix the resulting mixture with the polyisocyanate. Alternatively, all components of the foamable composition can be introduced separately. It is also possible to pre-react all or part of the reactive hydrogen-containing compound with the polyisocyanate to form the prepolymer.

Other conventional components of the foam formulation may optionally be present in the foamable composition of the present invention. For example, crosslinking or chain extenders, foam-stabilizing agents or surfactants, catalysts and fire-retardants can be used. Other possible ingredients include cell regulators, fillers (eg carbon black), pigments, fungicides, fungicides, antioxidants, adjuvant, antistatic agents and other additives or processing aids known to those skilled in the art.

Preferably, the foamable composition of the present invention comprises at least one surfactant. Suitable surfactants include fluorochemical surfactants, organosilicon surfactants, polyethylene glycol ethers of long chain alcohols, tertiary amine or alkanolamine salts of long chain alkyl acid sulfate esters, alkyl sulfonate esters, alkyl arylsulfonic acids, fatty acids Alkoxylates and mixtures thereof. Surfactants are generally used in amounts sufficient to stabilize the foam forming reaction mixture against collapse and formation of large, uneven cells. Typically, about 0.1 to about 5 weight percent of the surfactant is sufficient for this purpose. Organosilicone surfactants and fluorine compound surfactants are preferred.

Suitable catalysts for use in the preferred foamable compositions of the present invention include compounds which greatly accelerate the reaction of reactive hydrogen-containing compounds (or crosslinkers or chain extenders) with polyisocyanates. In use, the catalyst is generally present in an amount sufficient to effectively catalyze. Suitable catalysts include organometallic compounds (preferably organotin compounds), which may be used alone or preferably in combination with strong base amines. Representative examples of these and other types of suitable catalysts are described in US Pat. No. 4,972,002 (Volkert).

Foams made from the foamable compositions of the present invention may vary in texture from very soft types useful in the field of upholstery to rigid foams useful as structural or insulating materials. This foam can be used, for example, in the automotive, shipbuilding, airplane, furniture and fitness equipment industries, and is particularly useful as a thermal insulation material in the construction and refrigeration industries.

The following examples are set forth with the intention of further illustrating the present invention without intending to limit it. All percentages and parts in the examples are by weight unless otherwise indicated.

In the following examples and comparative examples, the thermal conductivity (lambda) value of the foam was measured on a 200 × 200 × ²⁵ cm ³ test sample to be perpendicular to the foam longitudinal direction. Thermal conductivity was measured after thermal aging at a temperature of 23 ° C. initially and at 50 ° C. for 3 weeks, with a reproducibility of ± 0.1 using a Hesto Lambda Control A-50 thermal conductivity analyzer.

Abbreviation

The following abbreviations were used in the examples.

Tradename Isocyanate 44V-20: Polymeric diisocyanate, commercially available from Bayer AG, having an isocyanate content of 31.5% by weight and a viscosity of 200 ± 40 cps at 25 ° C.

HFP dimer: Hexafluoropropene dimer (C ₆ F ₁₂ ) available from Hoechst AG.

HFP trimer: Hexafluoropropene trimer (C ₉ F ₁₈ ) available from Hoechst AG.

TFE-oligomer: a mixture of tetrafluoroethylene oligomer (C ₂ H ₄ ) _n , available from ICI, n = 4, 5 and 6.

Polyol 1832 A / 2: Bayer Aguerosa, hydroxy equivalent weight 520 mg KOH / g, water content 1.9 parts, catalyst content 3.7 parts N, N-dimethylcyclohexylamine and viscosity about 4000 cps at 25 ° C Polyether polyols commercially available under the tradename Baytherm VP-PU 1832 A / 2.

Silicone Surfactant B-8423: available from T.H.Goldschmidt.

HFE-1: perfluoropropyl methyl ether (C ₃ F ₇ OCH ₃ ), which may be prepared in column 20 as described in US Pat. No. 5,925,611 to Flynn et al.

HFE-2: Perfluorobutyl methyl ether (C ₄ F ₉ OCH ₃ ), available from 3M Corporation under the tradename NOVEC HFE-7100 Specialty Fluid.

rpm: revolutions per minute

pbw: parts by weight

Ex .: Examples

FC-10: trade name FLUORAD FC-10 fluorochemical alcohol (N-ethylperfluorooctylsulfonamidoethanol) commercially available from 3M.

Example 1

In Example 1, mixtures of perfluorocompounds, hydrocarbon blowing agents and hydrofluoroethers were prepared at different ratios and at various temperatures. N-pentane or cyclopentane / HFP dimer or HFP trimer / HFE-1 or HFE-2 at a ratio between 50/35/15 and 90/8/2 and at a temperature in the range from about -20 ° C to 20 ° C. It was observed that when a mixture was included, a clear solution was obtained.

Examples 2 and 3 and Comparative Examples C-1 and C-2

In Example 2, 3 parts of HFP dimer was added 0.5 parts of HFE-1, 15 parts of cyclopentane and 122 using 3.5 parts of silicone surfactant B-8423 and 6000 rpm of Pendraulic LD-50 high shear mixer. It was emulsified in negative polyol 1832A / 2. While stirring at 6000 rpm for 15 seconds, 199 parts of the brand name Desmodur V-20 were added to this emulsion. The resulting mixture was poured into a 350 cm x 350 cm x 60 cm aluminum mold and preheated at 50 ° C. Example 3 and Comparative Examples C-1 and C-2 were prepared according to substantially the same procedures as described in Example 2, except that the ingredients and amounts listed in Table 1 were used. The density and thermal conductivity data (initial value and value after heat aging) for the resulting foams are shown in Table 1.

ingredient Amount of ingredients (pbw) Example 2 Example 3 Comparative Example C-1 Comparative Example C-2 Polyol 1832 A / 2 122 122 122 122 Silicone B-8423 3.5 3.5 3.5 3.5 Isocyanates 44 V-20 199 199 199 199 Cyclopentane 15 15 15 15 HFP dimer 3 2.5 3.5 - HFE-1 0.5 One - 3.5 Density (kg / m ³ ) 26.9 25.4 25.0 26.2 Initial Thermal Conductivity (mW / mK) 19.5 20.0 19.6 21.0 Aging Thermal Conductivity (mW / mK) 21.2 22.0 21.4 24.1

As can be seen from the results given in Table 1, the thermal insulation properties of the foams made in Examples 2 and 3 and Comparative Example C-1 were almost identical. The polyol blends of Examples 2 and 3 were stable for 3 days (no phase separation was observed), while the polyol blends of Comparative Example C-1 were only stable for a few hours. The polyol blend of Comparative Example C-1 is therefore less commercially attractive because of its instability. The presence of HFE-1 makes the formulation more stable without significantly affecting the thermal insulation properties of the foam. The thermal conductivity data of Comparative Example C-2 prepared using only hydrofluoroether without using a perfluoro compound is inferior in thermal conductivity to foams prepared using a perfluoro compound.

Examples 4-9

In Examples 4-9, polyurethane foams were prepared substantially following the procedure of Example 2. The components and amounts are shown in Table 2. Density and thermal conductivity data for the resulting foams are shown in Table 2.

ingredient Amount of ingredients (pbw) Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Polyol 1832 A / 2 122 122 122 122 122 122 Silicone B-8423 - 3.5 3.5 3.5 3.5 3.5 Fluorocompound Surfactant * 3.5 - - - - - Isocyanate 44V-20 199 199 199 199 199 199 Cyclopentane 15 - 15 - 15 15 n-pentane - 15 - 15 - - HFP dimer 3.0 3.0 - - - 3.0 HFP trimer - - 3.0 3.0 - - C ₂ F ₅ COCF (CF ₃ ) ₂ - - - - 3.0 - HFE-1 - 0.5- 0.5 0.5 - - HFE-2 0.5 - - - 0.5 - cC ₆ F ₁₁ -CF ₂ OCH ₃ - - - - - 0.5 Density (kg / m ³ ) 24.8 26.1 27.8 27.2 26.8 25.9 Initial Thermal Conductivity (mW) 19.7 21.7 19.9 22.0 19.0 20.0 Aging thermal conductivity (mW) 21.4 25.9 21.8 25.6 21.4 22.0

Oligomeric fluorochemical surfactants described in Example 1 of US Pat. No. 3,787,351 (Olson).

The results indicate that polyurethane foams made using the blowing agent compositions of the present invention have good to very good thermal conductivity, both initially and after aging.

Examples 10 and 11

In Examples 10 and 11, polyurethane foams were prepared using fluorocompound-modified isocyanates prepared according to the following process: 197 g of Desmodur 44V- was placed in a 500 ml tri-neck flask equipped with a stirrer, thermometer and condenser. Filled with 20 and 2 g of fluorine alcohol FC-10. After heating the mixture to 75 ° C. for 4 hours under a nitrogen atmosphere, GLC showed that all of the fluorochemical alcohols had reacted.

A polyurethane foam was prepared substantially following the procedure of Example 2. The components and amounts are shown in Table 3. Density and thermal conductivity data for the resulting foams are reported in Table 3.

ingredient Amount of ingredients (pbw) Example 10 Example 11 Polyol 1832 A / 2 122 122 Silicone B-8423 3.5 - Fluorine Compound Surfactant ('351') - 3.5 Fluorine Compound Modified Isocyanates 199 199 Cyclopentane 15 - n-pentane - 15 HFP dimer 3.0 - TFE-oligomer - 3.0 HFE-1 - 0.5 HFE-2 0.5 - Density (kg / m ³ ) 27.8 26.4 Initial Thermal Conductivity (mW) 18.4 21.3 Aging thermal conductivity (mW) 20.6 25.0

This data shows that polyurethane foams prepared using fluorine modified isocyanates according to the invention had very good thermal conductivity both at the beginning and after 50 ° C. maturation.

Claims (13)

Evaporating a blowing agent composition comprising a perfluorocompound dissolved or dispersed in hydrofluoroether in the presence of at least one foamable polymer or precursor composition thereof, wherein the hydrofluoroether and perfluorocompound are at atmospheric pressure and about A process for producing polymer foam, which is liquid at 20 ° C. The method of claim 1 wherein the blowing agent composition further comprises a co-blowing agent other than the perfluorocompound or the hydrofluoroether. The method of claim 1 wherein the hydrofluoroether comprises a perfluorinated aliphatic group bonded to a hydrocarbon group by an oxygen atom. The method of claim 1, wherein the hydrofluoroether corresponds to the following formula. (R _h -O) _x -R _f Where x is 1 or 2, R _h represents an alkyl group having 1 to about 4 carbon atoms, R _f represents a perfluorinated aliphatic group comprising about two or more carbon atoms. The method of claim 1 wherein the perfluorine compound is selected from the group consisting of perfluorinated saturated or unsaturated hydrocarbon compounds having at least about 4 carbon atoms. The method of claim 2 wherein the co-expanding agent is a hydrocarbon. The method of claim 1, wherein the expandable polymer or precursor composition thereof comprises at least one organic polyisocyanate and at least one compound containing two reactive hydrogen atoms. Perfluorocompounds, hydrofluoroethers and co-foaming agents other than said perfluorocompounds and said hydrofluoroethers, wherein said perfluorocompounds and said hydrofluoroethers are homogeneous blowing agent compositions that are liquid at atmospheric pressure and at 20 ° C. . 10. The homogeneous blowing agent composition according to claim 8, wherein the co-expanding agent is a hydrocarbon compound, the perfluoro compound is a saturated or unsaturated hydrocarbon having at least about 4 carbon atoms perfluoro, and the hydrofluoroether corresponds to the formula . (R _h -O) _x -R _f Where x is 1 or 2, R _h represents an alkyl group having 1 to about 4 carbon atoms, R _f represents a perfluorinated aliphatic group comprising about two or more carbon atoms. A foamable composition comprising the foamable polymer according to claim 1 or a precursor composition thereof and a foaming agent composition. 11. The foamable composition of claim 10 wherein the blowing agent composition further comprises a co-blowing agent other than the perfluorocompound or hydrofluoroether. 12. The foamable composition of claim 11 wherein said perfluoro compound is selected from the group consisting of perfluorinated saturated or unsaturated hydrocarbon compounds having at least about 4 carbon atoms, and said hydrofluoroether corresponds to the formula: (R _h -O) _x -R _f Where x is 1 or 2, R _h represents an alkyl group having 1 to about 4 carbon atoms, R _f represents a perfluorinated aliphatic group comprising about two or more carbon atoms. The foamable composition of claim 11 wherein the foamable polymer or precursor composition thereof comprises at least one organic polyisocyanate and at least one compound containing two reactive hydrogen atoms.