JP2014524493A - Method for producing rigid polyurethane foam - Google Patents

Abstract

【Task】
The present invention relates to a particle-containing polyurethane foam in which particles are mainly incorporated in a cell wall.
[Selection figure] None

Description

  The present invention relates to a process for producing a rigid polyurethane foam by reacting a polyisocyanate with a compound having at least two hydrogen atoms which is reactive towards isocyanate groups.

  Rigid polyurethane foams have been known for a long time and are frequently described in the literature. Rigid polyurethane foams are usually produced by reacting a polyisocyanate with a compound having at least two isocyanate group reactive hydrogen atoms, in particular a polyfunctional alcohol. Rigid polyurethane foam is preferably used for vibration isolation or building elements in refrigeration equipment.

  Improving the properties of rigid polyurethane foam is an ongoing challenge. In particular, it is necessary to reduce the thermal conductivity of the foam and to improve the mechanical properties, in particular the compressive strength.

  A possible way to achieve this goal is to use filler-containing polyols in the production of rigid foams. A frequently used group of filler-containing polyols are those produced by in-situ polymerization of olefinically unsaturated monomers, especially styrene and / or acrylonitrile, in polyols, especially in polyether alcohols. Such products are generally known and are referred to as polymer polyols or graft polyols.

  The rigid polyurethane foam manufactured using a graft polyol is described in patent document 1 and patent document 2, for example. The hard foam described in the above document has a short release time, excellent mechanical properties, and low thermal conductivity.

  The uniform distribution of the particles in the foam matrix is important for the properties of the foam. Good distribution means that in the first step no agglomerates composed of a plurality of particles are formed and instead the filler is evenly distributed in the polymer material. Only in this case can the filler be used in an economically feasible manner. Such particle distribution can be realized by using a graft polyol as described in, for example, Patent Document 1 and Patent Document 2.

  In addition to the elimination of agglomerates, there is another important point for the distribution of particles in the foam. That is usually that at least 80% of the polyurethane material is present in the foam struts of rigid foam (see Non-Patent Document 1). Thus, virtually all particles are present in the bubble struts and only a few filler particles are present in the bubble wall. When the foam is subjected to high mechanical compressive or tensile stress, the material begins to break at its weakness, i.e. a very thin cell wall, but the much stronger cell struts remain initially intact. When reinforcing a foam with a filler, it is necessary that a substantial portion of the filler be present on the bubble wall because only the portion present in the bubble wall of all the fillers used has a reinforcing action. is there. According to the prior art, the distribution of the filler in such a state that the particle concentration of the bubble wall is high is not known.

  The use of fillers to optimize the properties of rigid polyurethane foam requires that the distribution of individual particles in the foam be substantially controlled.

International Publication No. 2005/097863 Pamphlet International Publication No. 2004/035650 Pamphlet

D. W. Reitz, M.M. A. Schutz, L.M. R. Gricksman “A basic study of aging insulation”, Journal of cellular plastics, 1984, 20 (2), 104-113.

  The object of the present invention is to provide a polyurethane foam, in particular a rigid polyurethane foam, which exhibits excellent mechanical properties, low thermal conductivity and excellent processing properties (eg reduced release time). In particular, it is necessary to improve the compressive strength of the foam, which allows a reduction in the density of the foam. Furthermore, it is also necessary to achieve a high compatibility of the starting components for the production of the polyurethane, in particular the polyol component, with the blowing agent (here in particular nonpolar hydrocarbons).

  The above object can be surprisingly solved mainly by particles incorporated in the foam wall of the foam, which are polymers or inorganic particles of olefinically unsaturated monomers, where the particle surface is surface active. It is denatured by the substance.

  Accordingly, the present invention is a particle-containing polyurethane foam in which the particles are mainly incorporated into the cell walls, the particles being a polymer or inorganic particle of an olefinically unsaturated monomer, and the particle surface being modified by a surface active substance. A polyurethane foam is provided.

  As used herein, the term “primarily” means that at least 50% by weight of particles, based on their total weight, are incorporated into the cell walls.

The present invention further includes
a) Polyisocyanate
b) a compound having at least two hydrogen atoms that is reactive towards isocyanate groups;
c) providing a process for producing a rigid polyurethane foam by reacting in the presence of a blowing agent;
Here, at least one of the components a) or b) comprises particles whose surface has been modified by a surface-active substance.

  The present invention further provides a particle-containing polyether alcohol that can be prepared by in situ polymerization of an olefinically unsaturated monomer in a polyether alcohol, wherein at least one of the olefinically unsaturated monomers has surface active properties.

  The present invention further provides a process for producing particle-containing polyether alcohols by in situ polymerization of olefinically unsaturated monomers in polyether alcohol, wherein at least one of the olefinically unsaturated monomers has surface active properties.

  For the purposes of the present invention, surface activity means that the compound compatibilizes immiscible materials, in particular immiscible liquids or immiscible liquids and gases. Such a compound has a group compatible with one material and a group compatible with the other material. Thus, the surface active compound becomes bound to the interface between the immiscible materials.

  The particles preferably have a size of less than 50 μm, in particular in the range from 0.5 to 10 μm.

  The particles are preferably selected from the group consisting of organic particles such as organic polymers or thermoplastic particles and inorganic particles, in particular carbon-rich particles such as carbon black or graphite, or oxides, in particular inorganic oxides.

  As mentioned above, the surface of the particle has surface activity because it has been modified by a surface-active substance, which is brought about in particular by applying a surfactant to the surface of the particle. Attachment of the surfactant to the particles can occur by non-covalent bonding or preferably by covalent bonding.

  In a preferred embodiment of the invention, the particles are inorganic particles. The inorganic particles are preferably carbon-rich particles as described above, such as carbon black or graphite or inorganic oxides, in particular metal oxides.

  In the case of inorganic particles, the surfactant is preferably contacted with the particles in such a way that the surfactant adheres to the surface of the particles.

  In a further preferred embodiment of the invention, the particles are polymers of olefinically unsaturated monomers.

  In this case, the particles can be thermoplastic particles dispersed in component a) or preferably b). Such a process is also known as a melt emulsification process and is known, for example, described in PCT International Patent Publication No. 2009/138379.

  Again, as with the inorganic particles, the surfactant is preferably contacted with the particles in such a way that the surfactant adheres to the surface of the particles.

  In a particularly preferred embodiment of the invention, the particles are produced by in-situ polymerization of olefinically unsaturated monomers in polyols, especially polyether alcohols. Polyols prepared by this method are generally known and are often referred to as graft polyols.

  The synthesis of graft polyols by two processes is known and is described in numerous examples. The production of graft polyols by a semi-batch process is described in the following patents: EP 439755 and US Pat. No. 4,522,976. A special form of semi-batch process is the semi-batch seed process, which additionally uses a graft polyol as a seed in the initial charge of the reaction, as described for example in EP 510533 and EP 698628. . The synthesis of graft polyols by a continuous process is also known and is described in particular in PCT International Patent Publication No. 00/59971 and PCT International Patent Publication No. 99/31160.

  In the case of organic particles prepared by polymerization, in particular organic particles prepared by in-situ polymerization of olefinically unsaturated monomers in polyether alcohol, preferably at least of a monomer having a surfactant group and at least one olefinic group. Preferably, the surfactant is introduced into the particles by one.

  Such monomers can be prepared by reacting a surfactant having at least one reactive group with a compound having a group reactive to this group and an olefinically unsaturated group.

  It is preferred to use a surfactant that can compatibilize the liquid and gas by non-covalent interactions. Such compounds are frequently used as foam stabilizers in the production of polyurethanes.

  A preferred example of such a surfactant is a polyether siloxane having at least one side chain having at least one hydroxy group, for example, a polyether siloxane of the following formula.

  Wherein x, y, z, n and m are numbers, R is an alkyl group having 1 to 10 carbon atoms, M has 2 to 10 carbon atoms, ether, ester, It is a divalent aliphatic, aromatic or araliphatic group bonded to the polyether chain via a urethane or acetal group. The sum of x, y and z is preferably selected such that the molecular weight of the siloxane chain in these compounds is, for example, 2000 to 6000 g / mol, preferably 4000 to 5500 g / mol. z is preferably 1 or 0, average 0.9, and y is preferably in the range of 3-20. x is defined accordingly. n and m are preferably selected according to the invention so that the side chains have a molecular weight of 400-2500 g / mol. The ratio n / (n + m) is preferably in the range of 10-90%, and the values of m / (n + m) are preferably similar.

  Accordingly, the present invention preferably provides the process of the present invention using a polyether siloxane having at least one side chain having at least one hydroxyl group as a surfactant.

  Furthermore, the present invention preferably provides the foam of the present invention, wherein the surface active material is a polyether siloxane having at least one side chain having at least one hydroxyl group.

  Furthermore, the present invention preferably provides a particle-containing polyether alcohol of the present invention that can be prepared by in situ polymerization of an olefinically unsaturated monomer in a polyether alcohol, wherein at least one of the olefinically unsaturated monomers is It has surface activity as a result of using a polyether siloxane having at least one side chain with at least one hydroxyl group.

  The present invention preferably also provides a process of the invention for preparing a particle-containing polyether alcohol by in situ polymerization of an olefinically unsaturated monomer in a polyether alcohol, wherein at least one of the olefinically unsaturated monomers is Have surface activity as a result of using polyether siloxanes with at least one side chain having at least one hydroxyl group.

  The molecular weight of the siloxane chain in these compounds is, for example, 2000 to 6000 g / mol, preferably 4000 to 5500 g / mol. The molecular weight of these compounds is, for example, 10000 to 25000 g / mol, preferably 11000 to 22000 g / mol, and particularly preferably 11000 to 20000 g / mol.

  Hydroxyl groups can react with unsaturated compounds having at least one group that is reactive towards isocyanate groups. These groups can be acidic groups or acid anhydride groups. Examples of such unsaturated acids and acid derivatives are maleic anhydride (MAn), fumaric acid, acrylate derivatives and methacrylate derivatives. Preferred is MAn. This group is preferably an isocyanate group since the resulting urethane group is more stable to hydrolysis than the ester group. Examples of unsaturated isocyanates are 3-isopropenyl-1,1-dimethylbenzyl isocyanate (TMI) and isocyanatoethyl methacrylate, with TMI being preferred. These compounds with olefinically unsaturated groups are often referred to as macromers or stabilizers.

  Further macromers which can be used instead of or preferably in combination with the above compounds usually have a molecular weight Mw of 1000 g / mol and contain at least one (usually terminal) reactive olefinically unsaturated group. Including linear or branched polyetherols. Ethylenically unsaturated groups are ethylenically unsaturated carboxylic acids and / or carboxylic anhydrides such as maleic anhydride, fumaric acid, acrylate derivatives and methacrylate derivatives, and unsaturated isocyanate derivatives such as 3-isopropenyl-1,1. -It can be inserted into existing polyols by reaction with dimethylbenzyl isocyanate, isocyanatoethyl methacrylate. Another route is the preparation of polyols by alkoxylation of propylene oxide and ethylene oxide with starting molecules having hydroxy groups and ethylenic unsaturation.

  Examples of such macromers are described in US Pat. No. 4,390,645, US Pat. No. 5,364,906 and US Pat. No. 6,013,731.

  Surfactants can be incorporated into the macromer.

  In a further embodiment of the invention, the graft polyol is prepared by in-situ polymerization of olefinically unsaturated monomers in polyether alcohol, wherein the graft particles are modified after reaction by reaction with surface active ingredients.

  In one embodiment of the present invention, the surfactant does not contain any halogen atoms, and in particular does not contain any fluorine atoms.

  These monomers adhere to the surface of the particles during the preparation of the graft polyol.

  As a result, the particles behave like surface active substances.

  The surface-active particles used according to the invention can additionally have functional groups, preferably the particles can be chemically bonded to the PU matrix via the groups. However, the particles of the present invention can have no reactive functional group on the surface.

  As mentioned above, the foams of the present invention are prepared by reacting a) a polyisocyanate with b) a compound having at least two hydrogen atoms that are reactive towards isocyanate groups, wherein component a ) And b), preferably component b) comprises particles.

  Incorporating particles in component a) is less preferred because the high reactivity of the polyisocyanate can lead to malfunctions and undesirable secondary reactions.

  Therefore component b) preferably comprises particles whose surface has been modified by a surface-active substance.

  Particle-containing polyols, particularly polyether alcohols, as described, can be produced in a preferred embodiment by in situ polymerization of olefinically unsaturated monomers in polyether alcohols (often referred to as carrier polyols). These polyols are often referred to as graft polyols.

  The carrier polyol is preferably prepared by addition of alkylene oxide, in particular ethylene oxide and / or propylene oxide, to an H-functional compound, preferably a compound having a hydroxy group or an amino group. The H-functional compound can be an alcohol having 2 to 4 hydroxy groups in the molecule. Preferred examples are glycerol, trimethylolpropane and glycols such as ethylene glycol, diethylene glycol, propylene glycol and dipropylene glycol. In a further embodiment of the invention, the H-functional compound is a primary or secondary amine having 2 to 4 reactive hydrogen atoms. Examples of aliphatic amines are ethylenediamine, propylenediamine and ethanolamine. Preference is given to using aromatic amines, preferably toluenediamine, in particular the ortho isomer thereof.

  The carrier polyol preferably has a hydroxy value in the range of 40 to 250 mg KOH / g.

  The solid content of the graft polyol is preferably in the range of 30 to 55% by weight, based on the total weight of the graft polyol.

  As olefinically unsaturated monomers, preferably styrene and / or acrylonitrile, particularly preferably a mixture of styrene and acrylonitrile is used. The acrylonitrile content of this mixture is particularly preferably in the range from 30 to 80% by weight, based on the mixture.

  The graft polyol b1) preferably has a polymer particle size of 0.1 μm to 8 μm, preferably 0.2 μm to 4 μm and a maximum particle size of 0.2 to 3 μm, preferably 0.2 to 2.0 μm. It is.

  In a further preferred embodiment of the graft polyol b1), the particle size distribution is bimodal, i.e. the particle size distribution curve has two maxima. Such graft polyols can be prepared, for example, by mixing polymers of olefinically unsaturated monomers with a suitable ratio of graft polyols having a unimodal particle size distribution and different particle sizes, or during the initial charge of the reaction. It can be produced by using a polyol already contained as a carrier polyol. Also in this embodiment, the particle size is in the above range.

  In one embodiment of the invention, the graft polyol can be prepared continuously.

  In a further preferred embodiment, the graft polyol is prepared by a semi-batch process.

  The following details are provided regarding the production of polyurethane foams, particularly rigid foams.

  The organic polyisocyanates a) that can be used are preferably aromatic polyfunctional isocyanates.

  Specific examples are tolylene-2,4- and 2,6-diisocyanate (TDI) and its isomer mixtures, diphenylmethane 4,4'-, 2,4'- and 2,2'-diisocyanate (MDI) and its isomers. Body mixture, mixture of diphenylmethane 4,4'- and 2,4'-diisocyanate, polyphenylpolymethylene polyisocyanate, diphenylmethane 4,4'-, 2,4'- and 2,2'-diisocyanate and polyphenylpolymethylene A mixture of polyisocyanates (crude MDI) and a mixture of crude MDI and tolylene diisocyanate. Organic diisocyanates and polyisocyanates can be used individually or in the form of mixtures.

  Also frequently used are modified polyfunctional isocyanates, ie products obtained by chemical reaction of organic diisocyanates and / or polyisocyanates. By way of example, diisocyanates and / or polyisocyanates having isocyanurates and / or urethane groups may be mentioned. Modified polyisocyanates are optionally selected from each other or from unmodified organic polyisocyanates (eg, diphenylmethane 2,4′-, 4,4′-diisocyanate, crude MDI, tolylene 2,4- and / or 2,6-diisocyanate). Can be mixed.

  Furthermore, reaction mixtures of polyfunctional isocyanates and polyhydric polyols and mixtures of other diisocyanates and polyisocyanates can also be used.

  Crude MDI having an NCO content of 29 to 33% by weight and a viscosity at 25 ° C. in the range of 150 to 1000 mPa · s has been found to be particularly useful as an organic polyisocyanate.

  The particle-containing polyol bi1) can in principle be used as a single compound b) having at least two hydrogen atoms which are reactive towards isocyanate groups. However, this compound b1) is preferably used in admixture with other compounds having at least two hydrogen atoms which are reactive towards isocyanate groups.

  For this purpose, customary and known compounds having at least two hydrogen atoms which are reactive towards isocyanate groups can be used. Preferably, polyether alcohols and / or polyester alcohols are used in combination with polyol b1).

  The polyester alcohol used with the polyol b1) usually contains 2 to 12 carbon atoms, preferably a polyfunctional alcohol having 2 to 6 carbon atoms (preferably a diol) and 2 to 12 carbon atoms. Polyfunctional carboxylic acids (e.g. succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid, preferably phthalic acid, isophthalic acid, terephthalic acid and isomeric naphthalene dicarboxylic acid Acid) condensation.

  The polyether alcohols used with polyols b1) usually have a functional number in the range 2-8, in particular 3-8.

  In particular, polyether alcohols prepared in a known manner, for example by anionic polymerization of alkylene oxides in the presence of a catalyst, preferably an alkali metal hydroxide, are used.

  As alkylene oxide, usually ethylene oxide and / or propylene oxide, preferably pure 1,2-propylene oxide is used.

  As starting molecules, compounds with at least 3, preferably 4-8 hydroxy groups or at least 2 primary amino groups in the molecule are used in particular.

  As starting molecules having in the molecule at least 3, preferably 4-8, preferably trimethylolpropane, glycerol, pentaerythritol, sugar compounds (eg glucose, sorbitol, mannitol and sucrose), polyhydric phenols , Resols (eg, oligomeric condensation products of phenol and formaldehyde and Mannich condensation products of phenol, formaldehyde and dialkanolamine), and melamine.

  As starting molecules having at least two primary amino groups in the molecule, preferably aromatic diamines and / or polyamines such as phenylenediamine, 2,3-, 2,4-, 3,4- and 2,6- Toluenediamine (TDA), in particular 2,3- and 3,4-TDA, and 4,4'-, 2,4'- and 2,2'-diaminodiphenylmethane, as well as aliphatic diamines and polyamines such as ethylenediamine. use. The 2,3- and 3,4-isomers of TDA are also referred to as vicinal TDA.

  The polyether alcohol preferably has a functionality of 3 to 8 and a hydroxy number of preferably 100 mg KOH / g to 1200 mg KOH / g, in particular 240 mg KOH / g to 570 mg KOH / g.

  In a preferred embodiment of the process according to the invention, the mixture of the graft polyol bi1) and at least one polyether alcohol bii2) initiated with an aliphatic amine is at least two hydrogens which are reactive towards isocyanate groups. Used as a compound with atoms. This polyether alcohol bii2) preferably has a hydroxy value in the range of 375 to 525 mg KOH / g.

  In a further preferred embodiment of the process of the invention, the mixture of the graft polyol bi1) and at least one polyether alcohol bii3) initiated with an aromatic amine is at least two reactive to isocyanate groups. Used as a compound having a hydrogen atom. This polyether alcohol bii3) preferably has a hydroxy value in the range of 375 to 525 mg KOH / g. Furthermore, polyether alcohols having a hydroxy value of 100 to 250 mg KOH / g using vicinal TDA as a starting molecule can be used as polyol bii3).

  In a further preferred embodiment of the invention, at least two mixtures of graft polyols bi1) and at least one polyether alcohol bii4) initiated with sugars, in particular sorbitol or sucrose, are reactive towards isocyanate groups. It is used as a compound having a hydrogen atom. This polyether alcohol bii4) preferably has a hydroxy value in the range of 300 to 700 mg KOH / g.

  In a further preferred embodiment of the invention, a mixture of graft polyols bi1) and at least one polyether alcohol bii5) initiated with a trihydric alcohol, in particular glycerol and / or trimethylolpropane, reacts with isocyanate groups. It is used as a compound having at least two hydrogen atoms which is sexual. This polyether alcohol bii5) preferably has a hydroxy value in the range of 100 to 250 mg KOH / g.

  In a further preferred embodiment of the invention, the polyol bi) or bii) comprises a polyether alcohol bii6) started with a bifunctional alcohol.

  In a further preferred embodiment of the invention, the compound b) comprises at least one polyol bii1), at least one polyol bii4) and at least one polyol bii2) and / or bii3).

  Preferred polyol components are 10 to 30% by weight polyol bii1, 0 to 15% by weight polyol bii2, 15 to 40% by weight bii3, 25 to 60% by weight bii4, and 0 to 15% by weight. Contains bii5 in a proportion of 15% by weight.

  Compound b) having at least two isocyanate-reactive hydrogen atoms also includes chain extenders and crosslinkers that may optionally be used in combination. Rigid polyurethane foams can be produced with or without chain extenders and / or crosslinkers. The addition of a bifunctional chain extender, a tri- or higher functional cross-linking agent, or optionally a mixture thereof can be advantageous for adjusting the mechanical properties. As chain extenders and / or crosslinkers, preferably alkanolamines are used, in particular diols and / or triols with a molecular weight of less than 400, preferably in the range from 60 to 300.

  Chain extenders, crosslinkers or mixtures thereof are advantageously used in an amount of 1 to 20% by weight, preferably 2 to 5% by weight, based on the compound b) having at least two isocyanate-reactive hydrogen atoms. Is done.

The reaction is usually carried out in the presence of catalysts, blowing agents and conventionally used auxiliaries and / or additives.

  As the catalyst, a compound that strongly accelerates the reaction between an isocyanate group and an isocyanate group-reactive group is particularly used.

  Such catalysts are strongly basic amines such as secondary aliphatic amines, imidazoles, amidines and alkanolamines or organometallic compounds, especially organotin compounds.

  If an isocyanurate group is also incorporated into the rigid polyurethane foam, a specific catalyst for that purpose is required. As the isocyanurate catalyst, a metal carboxylate, particularly potassium acetate and a solution thereof are usually used.

  The catalyst can be used alone or in combination with another catalyst depending on the requirements.

  As the foaming agent, water that reacts with isocyanate groups and discharges carbon dioxide is preferably used. It is also possible to use a physical blowing agent with water or instead of water. These are compounds that are inert to the starting components, are usually liquid at room temperature, and vaporize under urethane reaction conditions. The boiling point of these compounds is preferably less than 50 ° C. Physical blowing agents also include compounds such as carbon dioxide, low boiling alkanes and fluoroalkanes which are gaseous at room temperature and are charged or dissolved in the starting components under overpressure.

  Compounds usually contain alkanes and cycloalkanes having at least 4 carbon atoms, dialkyl ethers, esters, ketones, acetals, fluoroalkanes having 1 to 8 carbon atoms and 1 to 3 carbon atoms in the alkyl chain. It is selected from the group consisting of tetraalkylsilanes (especially tetramethylsilane).

Examples include propane, n-butane, isobutane and cyclobutane, n-pentane, isopentane and cyclopentane, cyclohexane, dimethyl ether, methyl ethyl ether, methyl butyl ether, methyl formate, acetone and in the troposphere, and thus harmless to the ozone layer Fluoroalkanes such as trifluoromethane, difluoromethane, 1,1,1,3,3-pentafluorobutane, 1,1,1,3,3-pentafluoropropane, 1,1,1,2-tetra tetrafluoroethane, difluoroethane and 1,1,1,2,3,3,3-heptafluoropropane), and perfluoroalkanes _{(e.g., C 3 F 8, C 4} F 10, C 5 F 12, C 6 F 14, Or C ₇ F ₁₇ ). The above physical blowing agents can be used alone or in combination with each other.

It is particularly preferred that the blowing agent comprises at least one aliphatic hydrocarbon, preferably comprising at least 4 carbon atoms. In a preferred embodiment of the process of the present invention, a combination of water and aliphatic hydrocarbon is used as the blowing agent. Preferred hydrocarbons are n-pentane, isopentane and cyclopentane.

  Optimal incorporation of the particles into the cell walls can occur, especially when hydrocarbons are used as the blowing agent.

  The process according to the invention can be carried out in the presence of flame retardants and conventionally used auxiliaries and / or additives, if necessary.

  As a flame retardant, an organic phosphate ester and / or a phosphonate ester can be used. Preference is given to using compounds which are not isocyanate group reactive. Chlorine-containing phosphonates are also included in the preferred compounds.

  Representative examples of this group of flame retardants are triethyl phosphate, diphenyl cresyl phosphate, tris (chloropropyl) phosphate and diethyl ethane phosphate.

  Furthermore, bromine-containing flame retardants can also be used. As the bromine-containing flame retardant, a compound having an isocyanate group-reactive group is preferably used. Such compounds are, for example, the alkoxylation products of aliphatic diol esters of tetrabromophthalic acid and dibromobutene diol. Compounds derived from brominated neopentyl compounds containing OH groups can also be used.

  As auxiliaries and / or additives, materials known per se for this purpose, such as surfactant substances, foam stabilizers, foam regulators, fillers, pigments, dyes, flame retardants, hydrolysis inhibitors, Antistatic agents, fungistatic agents and bacteriostatic agents are used.

  Further details regarding the starting materials, blowing agents, catalysts and auxiliaries and / or additives used to carry out the process of the invention can be found, for example, in Kunststoffhandbuch, volume 7, “Polyurethane” Carl-Hanser-Verlag, Munich. , 1st edition, 1966, 2nd edition, 1983 and 3rd edition, 1993.

  In order to produce rigid polyurethane foams, polyisocyanate a) is combined with compound b) having at least two isocyanate group-reactive hydrogen atoms and an isocyanate index in the range from 100 to 220, preferably from 115 to 195. React in the correct amount. Rigid polyurethane foam can be produced batch-wise or continuously using known mixing equipment.

  The production of polyisocyanurate foams can also be carried out at higher indices, preferably up to 350.

  The rigid PUR foam of the present invention is usually produced by a two-component process. In this process, compound b) having at least two isocyanate group-reactive hydrogen atoms is mixed with flame retardant, catalyst c), blowing agent d) and further auxiliaries and / or additives to obtain a polyol component. This is reacted with a polyisocyanate or polyisocyanate mixture, also called isocyanate component, and an optional blowing agent.

  The starting components are usually mixed at a temperature of 15 to 35 ° C, preferably 20 to 30 ° C. The reaction mixture can be cast into a closed support using a high pressure or low pressure metering machine.

  Furthermore, the reaction mixture can also be injected or sprayed onto the surface or into the open hollow space. This method allows the roof and complex containers to be insulated in the field. The reaction mixture can be introduced into the closed mold from one place or from several places at the same time, which mold may also have complex geometries. The reaction mixture can be injected from various locations on the mold. The mold can have a different arrangement in three-dimensional space when the reaction mixture is injected. The manufacture of refrigeration equipment is a typical example of such a process. The reaction mixture can likewise be poured into an open mold that is sealed after filling. This procedure is common, for example, in the manufacture of refrigerator doors.

Preparation of Graft Polyol The graft polyol used in the following examples can be prepared in a continuous process and a discontinuous process. The synthesis of graft polyols by two types of processes is known. The synthesis of graft polyols by a semi-batch process is described, for example, in EP 439755. A special form of semi-batch process is the semi-batch seed process, in which the graft polyol is additionally used as a seed during the initial charge of the reaction, as described for example in EP 510533. The synthesis of graft polyols having a bimodal particle size distribution is described in PCT International Publication No. 03/078496. The synthesis of graft polyols by a continuous process is likewise known and is described, for example, in PCT International Publication No. 00/59971.

  The graft polyols for the examples and comparative examples were prepared by a semi-batch process.

  The preparation of graft polyols for the examples and comparative examples by a semi-batch process was carried out in a 2 liter autoclave fitted with a two-stage stirrer, an internal cooling coil and an electric heating mantle. Prior to starting the reaction, the reactor was charged with a mixture of carrier polyol and macromer, flushed with nitrogen and heated to a synthesis temperature of 125-130 ° C. In some syntheses, in addition to the carrier polyol and macromer, the graft polyol was added as a seed during the initial charge of the reaction. In a further group of experiments, only a portion of the macroma was initially charged to the reactor. The remaining amount was introduced into the reactor during synthesis via an independent feed stream.

  The remainder of the reaction mixture further comprising carrier polyol, starting material, monomer and reaction modifier was placed in at least two feed vessels. The synthesis of the graft polyol was carried out by transferring the raw material from the supply container to the reaction container through the static in-line mixer at a constant supply rate. The introduction time of the monomer / regulator mixture was 150-180 minutes, while the polyol / initiator mixture was metered into the reactor over 165-195 minutes. Further, after a reaction time of 10 to 30 minutes at the reaction temperature, the crude graft polyol was transferred from the bottom discharge valve to the glass flask. This product was subsequently fed to unreacted monomers and other volatile compounds at a temperature of 135 ° C. under reduced pressure (<0.1 mbar). Subsequently, the final product was stabilized with antioxidants.

  Specific macromers were used for graft polyols 5-7. This was a polyether siloxane corresponding to the following formula:

Where x, y, z, n and m are numbers having the values given in the description, R is an alkyl group having 1 to 10 carbon atoms, and M is 2 to 10 carbon atoms. And is a divalent aliphatic, aromatic, or araliphatic group bonded to a polyether chain via an ether, ester, urethane, or acetal group. For example, Tegostab B8462 is reacted with TMI at 80 ° C. using a molecular defect of dimethyl-meta-isopropenylbenzyl isocyanate (TMI) so that no more than one OH group per molecule of polyether siloxane reacts statically. It was.

Production of rigid foam (mechanical foaming)
Various polyols, stabilizers and catalysts were mixed with water and blowing agents in the ratios shown in Table 1. 100 parts by weight of the polyol component is a mixture of diphenylmethane diisocyanate and polyphenylene polymethylene polyisocyanate in the amounts shown in each example of Table 1 (NCO content is 31.5% by weight, viscosity is 200 mPa · s (25 ° C.)) And a Puromat (R) HD30 (Elastogran GmbH) high pressure foaming machine. The reaction mixture was poured into a mold having dimensions of 200 cm × 20 cm × 5 cm or 40 cm × 70 cm × 9 cm where it was allowed to foam. The properties and property data of the obtained foam are shown in Table 1.

  The rigid polyurethane foam produced by the process of the present invention can be produced with a very short release time based on a phase stable polyol component, resulting in a significant reduction in cycle time. Despite the presence of the graft polyol, a large amount of physical blowing agent is soluble in the polyol component so that the foam density in the component can be less than 30 g / l. The foam properties were outstanding with respect to compressive strength, thermal conductivity and foam surface quality (depression formation).

The polyurethane reaction mixture was poured into a 200 × 20 × 5 cm ³ mold (10% overfill) and after several hours, a 20 × 20 × 2 cm ³ test piece was cut from the center.

  The compressive strength was measured according to DIN5341 / DIN EN ISO604.

  The ratio of the particles in the bubble wall was determined by quantitative evaluation of a scanning electron micrograph of the foam.

  Determination of particles in the bubble wall: scanning electron micrograph, statistical evaluation of particles

  The invention is illustrated by the following examples. All data are in parts by weight unless otherwise noted. The index and flow coefficient are unitless.

  Polyol 1-polyvinyl alcohol derived from vicinal TDA and ethylene oxide and propylene oxide, hydroxy value 390 mg KOH / g.

  Polyol 2-polyether alcohol derived from sucrose, glycerol and propylene oxide, hydroxy value 440 mg KOH / g.

  Polyether alcohol derived from polyol 3-vicinal TDA and ethylene oxide and propylene oxide, hydroxy number 160 mg KOH / g.

  Polyol A graft polyol prepared by in-situ polymerization of styrene and acrylonitrile in polyether alcohol having a hydroxy value of 35 mg KOH / g, derived from 4-glycerol and propylene oxide, having a hydroxy value of 19 mg KOH / g. Macroma is a reaction product of sorbitol, ethylene oxide / propylene oxide and TMI, and has a molecular weight of 18000 g / mol.

  Polyol 5-A graft polyol similar to polyol 4 prepared in the presence of a polyether siloxane surfactant, i.e. a macromer of the above formula. The molecular weight of the siloxane chain in this compound is 4400 g / mol, 81% ethylene oxide and 19% propylene oxide are present in the side chain, and the molecular weight of these compounds is 13000 g / mol.

  Polyol 6-A graft polyol similar to polyol 4 prepared in the presence of a polyethersiloxane surfactant, i.e. a macromer of the above formula. The molecular weight of the siloxane chain in this compound is 5050 g / mol, the side chain contains 60% ethylene oxide and 40% propylene oxide, and the molecular weight of these compounds is 19000 g / mol.

  Polyol 7—A graft polyol similar to Polyol 4 prepared in the presence of a polyethersiloxane surfactant, ie a macromer of the above formula. The molecular weight of the siloxane chain in this compound is 5050 g / mol, 60% ethylene oxide and 40% propylene oxide are present in the side chain, and the molecular weight of these compounds is 16000 g / mol.

  The stabilizer is Tegostab B8462.

  The catalysts are N, N-dimethylcyclohexylamine, N, N, N ′, N ″, N ′ ″-pentamethyldiethylenetriamine and Lupragen N600 (1,3,5-tris (dimethylaminopropyl) -sym-hexahydro. Triazine; S-triazine) in a 53:26:21 ratio.

  The foam according to the invention has an improved compressive strength. Therefore, the foam density of the foam of the present invention can be further reduced in the future than in the case of conventional foams.

  A further advantage is a good curing of the surface part of the foam. Even after a short release time, the foam is hard and less flexible and deformable than in the comparative formulation. This is advantageous for handling foam immediately after manufacture

Claims (17)

  A particle-containing polyurethane foam, wherein the particle is mainly incorporated in the cell wall, the particle is a polymer or inorganic particle of an olefinically unsaturated monomer, and the surface of the particle is modified with a surface active substance. A particle-containing polyurethane foam characterized by the following.   The foam of claim 1, wherein the surface active material is a polyether siloxane having at least one side chain having at least one hydroxyl group. a) Polyisocyanate
b) a compound having at least two hydrogen atoms that is reactive towards isocyanate groups;
c) in the presence of a blowing agent,
A method of producing a rigid polyurethane foam by reacting,
A method wherein at least one of components a) or b) comprises particles whose surface has been modified by a surface-active substance.   4. Process according to claim 3, characterized in that polyether siloxanes having at least one side chain having at least one hydroxyl group are used as surfactants.   The method according to claim 3 or 4, wherein the particles are present in the component b).   Said component b) comprises at least one particle-containing polyether alcohol bi), said bi) comprising at least two hydrogen atoms reactive towards isocyanate groups, and the olefinic properties in the polyether alcohol. 6. Process according to any one of claims 3 to 5, characterized in that it is prepared by in situ polymerization of saturated monomers and at least one of the monomers contains olefinically unsaturated bonds and surface active groups.   Said component b) comprises at least one particle-containing polyether alcohol bi), said bi) comprising at least two hydrogen atoms reactive towards isocyanate groups, and the olefinic properties in the polyether alcohol. 7. Process according to any one of claims 3 to 6, characterized in that it is prepared by in-situ polymerization of saturated monomers and the grafted particles are modified by reaction with surface-active components after their production.   8. A process according to any one of claims 3 to 7, wherein component b) comprises at least one further polyol bii).   9. A process according to any one of claims 3 to 8, characterized in that the polyol bi) or bii) comprises a polyether alcohol bii2) initiated with an aliphatic amine.   9. A process according to any one of claims 3 to 8, characterized in that the polyol bi) or bii) comprises a polyether alcohol bii3) initiated with an aromatic amine.   9. A process according to any one of claims 3 to 8, characterized in that the polyol bi) or bii) comprises a polyether alcohol bii4) initiated with a sugar.   9. A process according to any one of claims 3 to 8, characterized in that the polyol bi) or bii) comprises a polyether alcohol bii5) initiated with a trifunctional alcohol.   9. Process according to any one of claims 3 to 8, characterized in that the polyol bi) or bii) comprises a polyether alcohol bii6) started with a bifunctional alcohol.   14. Process according to any one of claims 3 to 13, characterized in that compound b) comprises at least one polyol bii4) and at least one polyol bi1) and / or bii2).   A particle-containing polyether alcohol that can be prepared by in-situ polymerization of an olefinically unsaturated monomer in a polyether alcohol, wherein at least one of the olefinically unsaturated monomers has surface-active properties alcohol.   A method for preparing a particle-containing polyether alcohol by in-situ polymerization of an olefinically unsaturated monomer in a polyether alcohol, wherein at least one of the olefinically unsaturated monomers has surface active properties.   16. A process for the preparation of particle-containing polyether alcohols according to claim 15 by in-situ polymerization of olefinically unsaturated monomers in polyether alcohols, characterized in that the preparation is carried out in a semi-batch process.