MXPA97006139A - Procedure for the production of a rigid depoliurethane foam and a composition for the production of a polyurethane rig foam - Google Patents

Abstract

The present invention relates to a process for the production of a rigid polyurethane foam, in which a polyisocyanate containing a benzene ring is used as an organic isocyanide and a polyether polyol and / or polyester polyol is used as the polyol, characterized in that , a hydrocarbon is used as the blowing agent and a compound having a hydrophobic group and a hydroxyl group in the molecule is used as the emulsifying agent

Description

PROCEDURE FOR THE PRODUCTION OF A FOAM RIGID POLYURETHANE AND A COMPOSITION FOR THE PRODUCTION OF A RIGID POLYURETHANE FOAM DESCRIPTION OF THE INVENTION The present invention relates to a process for the production of a rigid polyurethane foam, to a composition for the production of a rigid polyurethane foam and to the use of this rigid polyurethane foam as thermal insulation material. Chlorofluorocarbons (hereinafter referred to as CFCs) have been used to date as blowing agents for rigid polyurethane foams. In particular, trichlorofluoromethane (Rll) has been used. However, since CFCs contain chlorine, their use as blowing agents has given rise to aspects related to environmental problems involved in the depletion of the ozone layer in the stratosphere and in global warming. In order to protect the global environment, the production and use of CFCs are now prohibited and CFCs must be replaced by substitutes. At present, hydrofluorochlorocarbon (HCFC) blowing agents having a reduced ozone depletion factor are used as blowing agents. For example, HCFC-14lb (1, 1-dichloro-1-f luoroethane), HCFC-22 (chlorodifluoromethane), HCFC-142b (1-chloro-l, 1-difluoroethane), are produced industrially and are already used as agents of REF: 25273 expansion for thermal insulation. However, HCFCs also contain a chlorine atom in the molecule and, therefore, still have depletion of the ozone layer, although the degree of it is small. At an international level, restrictions have been imposed on the use of chlorinated compounds and their use is being reduced gradually. Therefore, in view of the need for environmental protection, the use of an expansion agent that has no effect on the ozone layer has recently been proposed. In certain uses, a hydrocarbon expansion agent that does not contain chlorine atoms and does not cause depletion of the ozone layer (eg, cyclopentane) has already been used. Rigid polyurethane foams, in which cyclopentane has been used as a blowing agent, have good thermal insulation properties and, therefore, are widely used as thermal insulation in refrigerators, as building material for buildings or vehicles. However, although cyclopentane is a recommended blowing agent since it is harmless to the global environment, its compatibility with active hydrogen compounds such as polyols is quite bad, thus giving rise to poor long-term storage stability of the mixtures of polyols containing cyclopentane. When mixing a polyol and a hydrocarbon blowing agent, the phase stability of the polyol mixture can be improved by adding a compound such as a surfactant that acts as an emulsifying agent, but when using conventional surfactants such as polyoxyethylene alkyl ethers , polyoxyethylenephenols, alkylbenzenesulfonate salts, nonyl phenols and stearyl alcohol, the compatibility with the hydrocarbon expansion agent is improved, but the mechanical properties of the final polyurethane foam are diminished. Although it is known that conventional emulsifying agents can solve the problem of solubility, cyclopentane in polyols, such agents cause the final rigid polyurethane foam to become soft and also increase costs. Accordingly, when cyclopentane is used as the blowing agent, an improvement in the long-term storage stability of the polyol mixture is required, while maintaining the high thermal conductivity and mechanical strength of the thermal insulation material. The present invention provides a process for producing a rigid polyurethane foam comprising reacting a polyisocyanate containing a benzene ring as an organic isocyanate with a polyether polyol and / or polyester polyol in the presence of one or more catalysts., an expanding agent and, optionally, adjuvants and / or additives, characterized in that a hydrocarbon is used as the blowing agent and a compound having a hydrophobic group and a hydroxyl group in the molecule is used as the emulsifying agent. The present invention further provides a composition for the production of rigid polyurethane foams, comprising: (1) an organic isocyanate comprising a polyisocyanate containing a benzene ring, (2) a polyol comprising a polyether polyol and / or polyester polyol, (3) an expanding agent comprising a hydrocarbon, (4) an emulsifying agent comprising a compound with a hydrophobic group and a hydroxyl group in the molecule, (5) a catalyst and, optionally, adjuvants and / or additives. In the process according to the invention, (1) an organic polyisocyanate, (2) a polyol, (3) a blowing agent, (4) an emulsifying agent and (5) a catalyst are used. If necessary, adjuvants and / or additives such as (6) water, (7) a surfactant, (8) a chain extender and / or a crosslinking agent, (9) and other additives (e.g. flame retardant and charges). As organic polyisocyanate (1), a polyisocyanate is used as toluene diisocyanate (TDI), diphenylmethane diisocyanate and poly (polymethylene polyphenyl isocyanate) (polymer MDL) and one of its modified polyisocyanates, alone or as a mixture.

A modified polyvalent isocyanate can be used, that is, a product obtained by the partial chemical reaction of an organic di- and / or polyisocyanate. For example, a di- and / or polyisocyanate containing ester groups, urea, biuret, allophanate, carbodiimide, isocyanurate and / or urethane is used. For example, an organic compound containing a urethane group, preferably aromatic polyisocyanate with an NCO content of 33.6 to 15% by weight, preferably 31 to 21% by weight, such as, for example, 4-diisocyanate, can be used. , 4'-diphenylmethane, 2,4- or 2,6-tolylene diisocyanate, which is modified with a diol ,. triol, dialkylene glycol, trialkylene glycol or low molecular weight polyoxyalkylene glycol having a molecular weight of not more than 1,500. As di- or polyoxyalkylene glycol, a single compound or mixture can be used. For example, a diethylene-, dipropylene glycol, polyoxyethylene-, polyoxypropylene-, polyoxyethylene glycol or triol can be used. In addition, a prepolymer containing an NCO group having an NCO content of 25 to 9% by weight, preferably 21 to 14% by weight, based on the total weight can be used. This is prepared from a mixture of a polyester- and / or preferably polyether polyol, with 4,4'-diphenylmethane diisocyanate, 2,4'- and 4,4'-diphenylmethane diisocyanate, 2,4- diisocyanate. and / or 2, 6-toluene or crude MDl. In addition, liquefied polyisocyanates containing carbodiimide groups and / or isocyanurate groups are preferred. These polyisocyanates have an NCO content of 33.6 to 15% by weight, preferably 31 to 21% by weight. For example, it is prepared based on 4,4'-, 2,4'- and / or 2, 2'-diphenylmethane and / or 2,4- and / or 2,6-tolylene diisocyanate base. The polyol (2) is a polyether polyol or a polyester polyol. The polyether polyol is prepared by adding propylene oxide (PO) and / or ethylene oxide (EO) to an initial starting material such as ethylene glycol, propylene glycol, glycerol, trimethylolpropane, pentaerythritol, triethanolamine, ethylenediamine, toluenedia ina (TDA) and sugar. The polyether polyol can be prepared by a conventional process, for example, by adding at least one alkylene oxide containing an alkylene chain having 2 to 4 carbon atoms to a starting material having from 2 to 8, preferably from 3 to 8 reactive hydrogen atoms, by polymerization of anion in the presence of a catalyst, for example, an alkaline hydroxide such as sodium hydroxide and potassium hydroxide or an alkali metal alcoholate such as sodium methylate, sodium or potassium ethylate or potassium isopropylate, or by cation polymerization presence of a catalyst, such as, for example, a Lewis acid such as pentachloroantimony and boron fluoride-etherate, or clay. Examples of preferred alkylene oxide are tetrahydrofuran, 1,3-propylene oxide, 1,2- or 2,3-butylene oxide, styrene oxide and in particular, ethylene oxide, 1,2-propylene oxide, etc. . These alkylene oxides can be used alone or in admixture. As an initial molecule, water, an organic dicarboxylic acid such as succinic acid, adipic acid, phthalic acid and terephthalic acid can be used, a substituted aliphatic or aromatic diamine which may be substituted with an N-mono-, N, N- or N, N'-dialkyl group and has from 1 to 4 carbon atoms in the alkyl chain, for example, ethylenediamine, diethylenetriamine, triethylenetetraamine, 1,3-propylenediamine, 1,3- or 1,4-butylenediamma, 1,2-, 1 / 3-, 1 / 4-, 1,5- and 1,6-hexamethylenediamine, phenylenediamine, , 3-, 2,4- and 2,6-tolylenedia ina and 4,4'-, 2,4'- and 2, 2'-diaminodiphenylmethane, which may be substituted with a mono- or dialkyl group. Examples of additional possible reactive starting molecules are alkanolamines such as ethanolamine, diethanolamine, N-methyl- and N-ethyl-ethanolamine, N-methyl and N-ethyl-diethanolamine, triethanolamine and ammonia. Preferably, a polyvalent, in particular trivalent and / or higher valent alcohol such as ethanediol, 1,2-propanediol and 1,3-propanediol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerol is used. , trimethylolpropane, pentaerythritol, sorbitol and sucrose (sugar). Preferably, the polyether polyol has a functionality of from 3 to 8, with from 3 to 6 being particularly preferred. Its hydroxyl number preferably ranges from 300 to 850, with from 350 to 800 being particularly preferred. The polyester polyol used can be produced from a polyvalent carboxylic acid and a polyvalent alcohol, such as, for example, poly (ethylene terephthalate). The preferred polyester polyol can be prepared from, for example, an organic dicarboxylic acid of 2 to 12 carbon atoms, preferably an aliphatic dicarboxylic acid of 4 to 6 carbon atoms and a polyvalent alcohol, particularly a diol of 2 to 12. carbon atoms, preferably from 2 to 6 carbon atoms. Examples of dicarboxylic acid are succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decarboxycarboxylic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid and terephthalic acid. Instead of a free dicarboxylic acid, a corresponding dicarboxylic acid derivative can be used as a monoester or diester of the dicarboxylic acid, prepared by esterification with an alcohol of 1 to 4 carbon atoms or a dicarboxylic anhydride. Examples of dihydric and polyhydric alcohols, in particular diols, are ethanediol, diethylene glycol, 1,2- or 1,3-propanediol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1, 10 -decanodol, glycerol and trimethylolpropane. Preferably, ethanediol, diethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol or a mixture prepared from at least two of the aforementioned diols are used, in particular, a mixture prepared from 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol. In addition, a polyester polyol produced from a lactone such as e-caprolactone or a hydroxycarboxylic acid such as? -hydroxycaproic acid can be used. The amount of polyol (2) used preferably ranges from 40 to 100 parts by weight, in particular from 60 to 90 parts by weight, based on 100 parts by weight of organic isocyanate. The blowing agent (3) can be a hydrocarbon of 2 to 8, particularly of 4 to 6 carbon atoms (for example, an alkane or a cycloalkane). The blowing agent (3) can be selected from the group consisting of an alkane, a cycloalkane, a dialkyl ether, a cycloalkylene ether and a fluoroalkane (for example, a compound with a fluorine atom and a hydrogen atom) . Examples of alkanes are propane, n-butane, isobutane, n-pentane, isopentane and n-hexane. Examples of cycloalkane are cyclobutane, cyclopentane, cyclohexane, cycloheptane and cyclooctane. Examples of dialkyl ethers are dimethyl ether, methyl and ethyl ether or diethyl ether. An example of a cycloalkylene ether is furan. Examples of fluoroalkane are trifluoromethane, difluoromethane, difluoroethane, tetrafluoroethane, heptafluoropropane, etc. The blowing agent is preferably a hydrocarbon selected from a group consisting of cyclopentane, n-pentane and isopentane. Cyclopentane is particularly preferred. The amount of blowing agent (3) used preferably ranges from 3 to 50 parts by weight, particularly from 5 to 40 parts by weight, based on 100 parts by weight of the organic isocyanate. The compound used as emulsifying agent (4) reacts with the isocyanate to produce a rigid polyurethane foam. As a result, water forms. The formed water reacts with the organic isocyanate to form carbon dioxide. Gaseous carbon dioxide promotes expansion efficiency, which can result in the reduction of foam density. In the emulsifying agent (4), the hydrophobic group can be a hydrocarbon group, in particular, an alkyl group. The number of carbon atoms in the hydrocarbon group can vary from 5 to 40, particularly from 5 to 20. The hydrocarbon group is preferably branched. The emulsifying agent (4) is preferably a branched hydrocarbon compound containing a hydroxyl group. Examples of emulsifying agents (4) used are n-butanol, nonylphenol, t-butanol, lauryl alcohol and polyoxyethylenephenols. T-butanol is particularly preferred. The amount of emulsifying agent used varies preferably from 0.1 to 15 parts by weight, particularly from 0.2 to 5 parts by weight, based on 100 parts by weight of organic isocyanate. As catalyst (5), conventional and known amine catalysts and metal catalysts can be used. Examples of amine catalysts are a tertiary amine such as triethylene diamine, tetramethylhexamethylenediamine, pentamethyl diethylenetriamine, dimethyclohexyltriane and methyl morpholine. Examples of metal catalysts are organometallic compounds such as tin octoate, dibutyl tin dilaurate and lead octylate. The amount of catalyst (5) used preferably ranges from 0.001 to 5 parts by weight, particularly from 0.005 to 2 parts by weight, based on 100 parts by weight of organic isocyanate. Optionally, adjuvants and / or additives are used. The water (6) optionally used acts as an expanding agent. The amount of water (6) used preferably ranges from 0 to 5 parts by weight, particularly from 0.5 to 3 parts by weight, based on 100 parts by weight of organic isocyanate. The organic silicone compounds can optionally be used as surfactants (7). The amount of surfactant (7) preferably ranges from 0 to 5 parts by weight, particularly from 1 to 3 parts by weight, based on 100 parts by weight of organic isocyanate. Examples of the chain extenders and / or crosslinking agents (8) optionally used are an alkanolamine and a diol and / or triol, particularly with a molecular weight of not more than 400, preferably from 60 to 300. Examples of alkanolamine are ethanolamine and / or isopropanolamine. Examples of dialkanolamine are diethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine and diisopropanolamine. Examples of trialkanolamine are triethanolamine and triisopropanolamine. An adduct prepared from ethylene oxide or 1,2-propylene oxide and an alkylene diamine can be used with 2 to 6 carbon atoms in an alkylene chain, such as, for example, N, N'-tetra (2-hydroxyethyl) ethylene diamine and N, N'-tetra (2-hydroxypropyl) ethylene diamine. Additionally, an aliphatic, cycloaliphatic and / or aromatic diol of 2 to 14, preferably 4 to 10, carbon atoms can be used, for example, ethylene glycol, 1,3-propanediol, 1, 10-decanediol, or-, m- p-dihydroxycyclohexane, diethylene glycol, dipropylene glycol and, preferably 1,4-butanediol, 1,6-hexanediol and bis- (2-hydroxyethyl) -hydroquinone. Additionally, thiol, for example, 1,2,4-, 1, 3, 5-trihydroxycyclohexane and glycerol can be used. The amount of the chain extender and / or crosslinking agent (8) used preferably ranges from 0 to 20%, particularly from 2 to 5% by weight, based on the polyol. Examples of additives (9) optionally used are expansion stabilizers, foam controlling agents, fillers, dyes, pigments, flame retardants, hydrolysis inhibitors, anti-mold agents, bactericides and the like. The amount of additive (9) used preferably ranges from 1 to 40 parts by weight, particularly from 5 to 20 parts by weight, based on 100 parts by weight of the organic polyisocyanate. Examples of fillers are carbon black and calcium carbonate. Examples of suitable flame retardants are tricresyl phosphate, tris- (2-chloroethyl) phosphate, tris- (2-chloropropyl) phosphate, tris- (1,3-dichloropropyl) phosphate, tris- (2,3-dibromopropyl) phosphate, tetrakis- (2-chloroethyl) -ethylenediphosphate, etc. In addition to the aforementioned halogen-substituted phosphates, the following may be mentioned: an inorganic flame retardant such as red phosphorus, hydrated aluminum oxide, antimony trioxide, arsenic oxide, ammonium polyphosphate and calcium sulfate; a derivative of cyanuric acid such as melamine or a mixture of at least two types of flame retardants such as, for example, an ammonium polyphosphate and melamine. The equivalent ratio of isocyanate groups in the polyisocyanate to reactive hydrogen atoms of the polyol, the emulsifying agent and the chain extender and / or crosslinking agent varies from 0.85 to 1.25: 1, preferably 0.95 to 1.15; 1, with from 1.0 to 1, 10: 1 being particularly preferred. The rigid polyurethane foam can be prepared by a batch process or by a continuous process, by a prepolymer process or in an injection foaming process using known mixing equipment. The particularly preferred method is the binary method (which uses the components (A) and (B)).

The component (A) is formed by the organic polyisocyanate and the component (B) is formed by the rest of the constituents other than the organic polyisocyanate (1). The starting raw material components are mixed at 15 to 90 ° C, preferably at 20 to 35 ° C, and introduced into an open molding machine in which the temperature can be controlled. The reaction mixture expands without pressure in order to avoid peripheral compression. In order to produce, for example, a laminated composite material, a foamable reaction mixture is suitably injected or sprayed onto the back of the surface layer and expanded to form a rigid polyurethane foam. The rigid polyurethane foam preferably has a density of 20 to 100 kg / m3 and a thermal conductivity of 0.0140 to 0.0230 kcal / mh ° C.

The rigid polyurethane foams produced according to the invention can be used as a thermal insulation material, for example, as an intermediate layer in a laminated thermal insulation composite material, as an injectable foam for filling a hollow space inside a device of cooling and freezing, in particular, a refrigerator or a freezer, such as a thermal insulation envelope for containers for the storage of hot water or the thermal insulation of articles to be heated. In the following, the present invention is explained in more detail by means of examples and comparative examples.

Examples Examples 1 to 3 v Comparative Examples 1 to 3 A liquid formed by several polyols was prepared by mixing an amine catalyst (N, N-dimethylcyclohexylamine) (the amount necessary to adjust the reactive gelling time to about 50 seconds), parts by weight of a surfactant (L-5421, manufactured by Nippon Unicar Co., Ltd.) and 0.5 parts by weight of water with 50 parts by weight of polyol A, 30 parts by weight of polyol B and 20 parts by weight weight of polyol C. T-butanol or polyoxyethylene nonylphenol emulsifier was added to the liquid formed by several polyols and cyclopentane as blowing agent in order to prepare a mixture of polyols.

Polyol A: A polyol having a hydroxyl number of 450 g KOH / g and was obtained by the addition of propylene oxide (PO) using sugar as starting raw material. Polyol B: A polyol having a hydroxyl number of 400 mg KOH / g and obtained by the addition of PO using toluene diamine (TDA) as starting raw material. Polyol C: A polyol having a hydroxyl number of 380 mg KOH / g and was obtained by the addition of PO using ethylene diamine as starting raw material. Based on the formulation of Table 1, the aforementioned mixture of polyols (comprising the liquid formed by various polyols, cyclopentane, t-butanol or polyoxyethylene nonyl phenol) and polymeric MDl was mixed in a mixer. The temperature of the raw material ethane was adjusted to 20 ° C. The rigid polyurethane foam obtained by stirring and mixing the liquid urethane mixture was introduced into a mold made of aluminum and having dimensions of 600 mm x 400 mm x 50 mm. Seven minutes later, the molded article was removed from the mold. The properties of the foam of the former demolding article are shown in Table 2.

»Cremation Time: The time required for the foaming of the reaction mixture to become an opaque cream-like material was measured from the start of the stirring and mixing of the mixture of polyols and a liquid isocyanate. Gelification Time: The time required for the formation of fibers in the foam was measured with a rod nailed therein, since the mixing of the raw materials of the reaction begins.

Free Foam Density: The density of the foam was measured when free foaming occurs in a box made of a sheet material, whose internal dimensions are 150 mm x 300 mm x 150 mm. Compressive Strength: A 50 mm3 sample cut from the central portion of a foam was compressed in a direction vertical to the flow. An effort was measured (head speed of 10 mm / min) when its displacement reached 10%. Dimensional Stability at Low Temperature: The speed of dimensional deformation was measured when a sample of 50 mm3 was kept cut from the central portion of a foam at -30 ° C for 48 hours. Thermal Conductivity: The thermal conductivity of a sample with dimensions of 200 mm x 300 mm x 25 mm, which was cut from the central portion of a foam, was measured by means of a device to measure the thermal conductivity manufactured by Eikoseisha Co. , Ltd. (Autoramuda). The average temperature was 23.7 ° C.

Table 1 I Table 2 I M O I By changing the portions of cyclopentane added to a range of 17 to 24 parts by weight, the solubility was tested in a mixture of polyols (the mixture comprising a liquid consisting of several polyols and an emulsifying agent). The results are shown in the Table.

Table 3 I ro i 0: Uniform and transparent?: Opaque separation (white turbidity) x: Complete separation.

In Comparative Examples 1 and 2, when the conventional and known emulsifying agent, polyoxyethylene nonylphenol, is used, the solubility is improved, but the properties of the foam are deteriorated. However, when t-butanol is used according to the invention in Examples 1, 2 and 3, the solubility is improved and the good properties of the foam are maintained. In the present invention, the solubility of an expanding agent such as cyclopentane is improved. Accordingly, the long-term stability of a polyol mixture containing a blowing agent is improved. In addition, it is also possible to maintain a good thermal conductivity and a high mechanical strength of the thermal insulation material. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (5)

1. CLAIMS 1. A process for the production of a rigid polyurethane foam in which a polyisocyanate containing a benzene ring is used as an organic isocyanate and a polyether polyol and / or polyester polyol is used as the polyol, characterized in that a hydrocarbon as blowing agent and a compound having a hydrophobic group and a hydroxyl group in the molecule is used as an emulsifying agent.
2. 2. The process according to claim 1, characterized in that the blowing agent is a hydrocarbon selected from the group consisting of cyclopentane, n-pentane and isopentane.
3. 3. The process according to claim 1, characterized in that the emulsifying agent is a branched hydrocarbon containing a hydroxyl group.
4. 4. The process according to claim 3, characterized in that the emulsifying agent is t-butanol.
5. 5. A composition for the production of a rigid polyurethane foam, characterized in that it comprises. (1) an organic isocyanate comprising a polyisocyanate containing a benzene ring, (2) a polyol comprising a polyether polyol and / or polyester polyol, (3) an expanding agent comprising a hydrocarbon, (4) an emulsifying agent comprising a compound with a hydrophobic group and a hydroxyl group in the molecule, (5) a catalyst and, optionally, adjuvants and / or additives. . Use of a rigid foam produced according to the method of claim 1 to 4, as thermal insulation material.