JP6470611B2 - Method for producing polyurethane foam and polyurethane foam obtained thereby - Google Patents

Description

  The present invention relates to a method for producing a polyurethane foam and the polyurethane foam obtained thereby, in particular, an advantageous method for producing a polyurethane foam which effectively improves the foam density, and the density characteristics of the foam obtained thereby. The present invention relates to an excellent polyurethane foam.

  Conventionally, polyurethane foam has been used mainly as a thermal insulation member for its thermal insulation and adhesive properties, insulation for interior and exterior wall materials and panels for construction, metal siding, insulation for electric refrigerators, buildings and condominiums. -Practical for heat insulation and dew condensation prevention for frame walls, ceilings, roofs, etc. in refrigerated warehouses, and for infusion pipes, etc. In addition, such a polyurethane foam generally includes a polyol composition comprising a polyol compound liquid (premix liquid) in which a polyol compound is blended with a foaming agent and, if necessary, various auxiliary agents such as a catalyst, a foam stabilizer, and a flame retardant. The polyisocyanate is produced by continuously or intermittently mixing with a polyisocyanate, applying it to a foam forming site, reacting it, and foaming and curing.

  And as a foaming agent currently used for manufacture of such a polyurethane foam, hydrofluorocarbon type foaming agents such as HFC-134a, HFC-245fa, and HFC-365mfc, which are relatively superior in terms of global warming potential, are used. It has been known. This hydrofluorocarbon-based blowing agent is recognized as an alternative chlorofluorocarbon that causes little or no destruction of the ozone layer, but the use of such an alternative chlorofluorocarbon will be limited in the near future due to a strong demand for environmental destruction problems. Therefore, halogenated olefin-based blowing agents called hydrofluoroolefins and hydrochlorofluoroolefins that have a low global warming potential due to chemical instability have been developed instead.

  However, when a polyurethane foam is produced using such a halogenated olefin-based blowing agent, a large density difference occurs between the skin layer (surface layer) and the core layer of the resulting polyurethane foam, resulting in an overall density of the foam. As a result, the difference between the core density and the density of the skin layer increases, resulting in a problem that the amount of raw material used increases, and the density of the core layer decreases. The problem that strength and dimensional stability are reduced is caused. In particular, when performing in-situ foaming (spray foaming) in a place where the target polyurethane foam is to be formed, dripping is caused before the polyurethane foam (raw material) attached to the wall surface of the object is cured. In order to prevent this, the problem of the density difference becomes more prominent because it needs to be cured quickly.

  By the way, in Japanese translations of PCT publication No. 2007-536390 (Patent Document 1), 1,1,1,3-tetrafluoropropene (HFO-1234) and 1,1,1,3-tetrafluoropropene (HFO-1234) are used as foaming agents. Compositions comprising tetrafluoropropene such as HFO-1234ze) and carbon dioxide have been proposed, where such compositions are used as compositions to form polyurethane foams or polyisocyanurate foams. It is clear that it can be done. However, this patent document 1 does not disclose anything about adding supercritical, subcritical, or liquid carbon dioxide to such a composition, and foaming the composition. However, no mention is made of the fact that there is a difference in density between the skin layer and the core layer in the polyurethane foam, and furthermore, no measures are taken to eliminate such a density difference.

  In addition, Japanese Patent Publication No. 2013-504656 (Patent Document 2) discloses an improved polyurethane foaming process using a halogenated olefin-based foaming agent, in which a halogen such as HCFO-1233zd is disclosed. It is disclosed that by using a olefinic foaming agent, the flow of the liquid polyurethane foam before solidification is improved, and a more homogeneously dispersed liquid polyurethane foam can be generated, and such a polymer blowing agent composition is also disclosed. It has been clarified that carbon dioxide can be further added to the product together with such a halogenated olefin-based blowing agent. However, even in this Patent Document 2, there is no disclosure about the use of supercritical, subcritical, or liquid carbon dioxide as carbon dioxide. No disclosure has been made about any characteristics or problems that may occur when used, and in the examples, only polyurethane foam production methods by free foaming or molding are used. It has not been clarified, and in particular, no disclosure has been made that the density difference produced between the skin layer and the core layer is significant in in-situ blowing (spray) foaming.

Special table 2007-536390 Special table 2013-504656 gazette

  Here, the present invention has been made in the background of such circumstances, and the problem to be solved is caused by the production of polyurethane foam using a halogenated olefin-based foaming agent. Another object of the present invention is to provide a method for producing a polyurethane foam that is suitably employed in in-situ blowing and foaming.

  And, as a result of intensive studies by the present inventors in order to solve the above problems, together with hydrofluoroolefin and hydrochlorofluoroolefin, which are halogenated olefin-based foaming agents, supercritical, subcritical, or liquid dioxide dioxide. A combination of carbon and water as a foaming agent, and foaming with a small amount of supercritical, subcritical, or liquid carbon dioxide and water with respect to the halogenated olefin-based foaming agent. The present inventors have found that the density difference between the skin layer and the core layer can be advantageously relaxed and the physical properties as a foam can be effectively improved, and the present invention has been completed.

  That is, according to the present invention, when a polyurethane foam is produced by reacting a polyol composition and a polyisocyanate in the presence of a catalyst, and foaming / curing, to 100 parts by mass of the polyol in the polyol composition. In a ratio of 0.1 to 7 parts by mass, supercritical, subcritical or liquid carbon dioxide is added to the polyol composition or the polyisocyanate, and 0.05 to 7 parts per 100 parts by mass of the polyol. While the polyol composition contains water in a proportion of parts by mass, the polyol composition contains one or more foaming agents selected from the group consisting of hydrofluoroolefins and hydrochlorofluoroolefins. And the blowing agent comprising the supercritical, subcritical or liquid carbon dioxide and the polyurethane. It is present in the polyol composition in a ratio of more than 1 mole and 20 moles or less with respect to 1 mole of the total amount of carbon dioxide generated by the reaction of the polyisocyanate and the water during the production of foam. Thus, the gist of the method for producing a polyurethane foam, characterized in that the reaction is carried out.

  According to one preferred embodiment of the method for producing a polyurethane foam according to the present invention, a quaternary ammonium salt is contained in the polyol composition as one of the catalysts.

  Further, according to another preferred embodiment of the method for producing a polyurethane foam according to the present invention, the polyol composition and the polyisocyanate are sprayed on the surface of a predetermined structure to be foamed and cured. The foaming method is preferably employed.

The polyurethane foam obtained by the production method according to the present invention has a difference between the total density and the core density of 1 to 12 kg / m ³ .

  As described above, in the method for producing a polyurethane foam according to the present invention, an environmentally friendly polyurethane foam is formed using a halogenated olefin-based foaming agent composed of hydrofluoroolefin or hydrochlorofluoroolefin having a low global warming potential. When supercritical, subcritical, or liquid carbon dioxide is used in combination with water that generates carbon dioxide by reaction with polyisocyanate, a small amount of these are added to cause foaming. Thus, while ensuring the strength of the polyurethane foam to be formed, gas carbon dioxide is generated quickly and advantageously in the initial reaction between the polyol and the polyisocyanate, effectively increasing the density of the skin layer. The density difference between the core layer and the core layer can be advantageously reduced. From where it becomes possible to present more of the polyurethane resin content in the core layer, resulting compressive strength is advantageously increased polyurethane foam obtained, it is the is be able to and to reduce the dimensional change.

  Further, in the method for producing polyurethane foam according to the present invention, by using a quaternary ammonium salt as one of the catalysts, isocyanurate is advantageously produced from polyisocyanate, and the resulting polyurethane foam has compressive strength and dimensional stability. In addition, according to the present invention, the density of the skin layer and the core layer is obtained by foaming and curing the polyol composition and the polyisocyanate by an on-site spray foaming method according to the present invention. There is an advantage that an increase in the difference can be suppressed more remarkably.

And in the polyurethane foam obtained by the manufacturing method according to the present invention, the compressive strength of the foam can be effectively increased by configuring the difference between the total density and the core density to be 1 to 12 kg / m ^3. And dimensional stability can be advantageously reduced.

  Hereinafter, the polyurethane foam production method according to the present invention and the polyurethane foam obtained thereby will be described in detail.

  First, in the method for producing a polyurethane foam according to the present invention, a polyol composition and a polyisocyanate are mixed, reacted in the presence of a catalyst, and foamed and cured to obtain a desired rigid polyurethane foam. The polyol, which is the main component constituting the polyol composition used there, includes various known polyol compounds that react with polyisocyanate to produce polyurethane, either alone or appropriately. For example, polyether polyol, polyester polyol, and the like are preferably used in combination.

  Specifically, among such polyols, the polyether polyol is an alkylene oxide in at least one initiator such as a polyhydric alcohol, a saccharide, an aliphatic amine, an aromatic amine, a phenol, or a Mannich condensation product. Is obtained by reacting. Here, examples of the alkylene oxide include propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, and ethylene oxide. In addition, polyhydric alcohols as initiators include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, pentaerythritol, etc., and saccharides include sucrose, dextrose, sorbitol, etc. Furthermore, as aliphatic amines, there are alkanolamines such as diethanolamine and triethanolamine, polyamines such as ethylenediamine, etc., and aromatic amines include various methyl-substituted phenylenediamines collectively called tolylenediamine. In addition, derivatives in which a substituent such as methyl, ethyl, acetyl, benzoyl or the like is introduced into the amino group, 4,4′-diaminodiphenylmethane, p-phenylenediamine, o-phenylenediamine, Lid diamine and the like, as still yet phenols, bisphenol A, can be mentioned a novolak type phenolic resin. Examples of Mannich condensation products include Mannich condensation products obtained by subjecting phenols, aldehydes, and alkanolamines to a Mannich condensation reaction.

  Examples of polyester polyols include polyols of polyhydric alcohol-polycarboxylic acid condensation, and cyclic ester ring-opening polymerization. In this case, as the polyhydric alcohol, those described above can be used, and among them, dihydric alcohols are preferably used. Examples of the polyvalent carboxylic acid include succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, terephthalic acid, isophthalic acid, and anhydrides thereof. In addition, ε-caprolactone or the like is used as the cyclic ester.

  The polyol composition according to the present invention contains one or two or more halogenated olefin-based blowing agents selected from the group consisting of hydrofluoroolefins and hydrochlorofluoroolefins as foaming agents. It becomes. Examples of the hydrofluoroolefin used here include pentafluoropropene such as 1,2,3,3,3-pentafluoropropene (HFO1225ye), 1,3,3,3-tetrafluoropropene (HFO1234ze), 2 , 3,3,3-tetrafluoropropene (HFO1234yf), tetrafluoropropene such as 1,2,3,3-tetrafluoropropene (HFO1234ye), trifluoro such as 3,3,3-trifluoropropene (HFO1243zf) Hexafluorobutene isomers (HFO1336) such as propene, tetrafluorobutene (HFO1345), pentafluorobutene isomers (HFO1354), 1,1,1,4,4,4-hexafluoro-2-butene (HFO1336mzz) ), Hepta Examples include fluorbutene isomers (HFO1327), heptafluoropentene isomers (HFO1447), octafluoropentene isomers (HFO1438), nonafluoropentene isomers (HFO1429), and the like. Include 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd), 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), dichlorotrifluoropropene (HCFO1223), and the like. I can do it.

In the present invention, in addition to the halogenated olefin-based blowing agent, supercritical, subcritical, or liquid carbon dioxide (hereinafter abbreviated as liquefied CO ₂ ) is contained in the polyol composition. In a ratio of 0.1 to 7 parts by mass with respect to 100 parts by mass of the polyol, the polyol composition or polyisocyanate is further contained. Such liquefied CO ₂ is, as is well known, formed into a supercritical state, a subcritical state, or a liquid state by pressurizing carbon dioxide gas at a predetermined temperature. Specifically, liquid carbon dioxide is liquefied under a temperature and pressure condition at or above the triple point, and subcritical carbon dioxide is a pressure that is above the critical pressure and the temperature is critical. Carbon dioxide in a liquid state with a temperature below the temperature, carbon dioxide in a liquid state with a pressure below the critical pressure and a temperature above the critical temperature, or carbon dioxide with a temperature and pressure below the critical point but close to this. Further, the carbon dioxide in the supercritical state is a carbon dioxide in a fluid state in which both the pressure and temperature exceed the critical pressure and the critical point equal to or higher than the critical temperature.

Such liquefied CO ₂ is supplied to and mixed with the polyol composition flow path or the polyisocyanate flow path by a carbon dioxide supply device as disclosed in Japanese Patent Application Laid-Open No. 2008-285525. And contributes to the foaming of the polyurethane caused by the reaction between the polyol and the polyisocyanate in the polyol composition. Of course, such liquefied CO ₂ is supplied directly to the position where the polyol composition and the polyisocyanate are brought into contact with and mixed with each other, and liquefied CO ₂ is supplied to both of them. It is also possible to do so.

In addition, such liquefied CO ₂ contributes to the thinning of the skin layer in the resulting polyurethane foam by realizing the effective foaming action in the early stage of foaming, and advantageously achieves its low density. However, when the amount used is less than 0.1 parts by mass with respect to 100 parts by mass of the polyol in the polyol composition, the effect of the addition cannot be sufficiently exhibited. Insufficient foaming immediately after spraying by the foaming method increases the density difference between the core layer and the skin layer, causing problems such as a decrease in compressive strength and an increase in dimensional change rate. Become. On the other hand, when the amount of the liquefied CO ₂ used is more than 7 parts by mass with respect to 100 parts by mass of the polyol in the polyol composition, the gas (carbon dioxide) generated at the initial stage of the reaction becomes excessive, and foaming occurs. For example, when spraying in the spray foaming method, it is difficult to obtain a good foam. For this reason, in the present invention, the amount of liquefied CO ₂ used must be in the range of 0.1 to 7 parts by mass with respect to 100 parts by mass of the polyol in the polyol composition, preferably It will be in the range of 0.3-5 parts by mass, more preferably 0.5-3 parts by mass.

  Furthermore, the polyol composition according to the present invention contains 0.05 to 7 parts by mass of water with respect to 100 parts by mass of the polyol in the polyol composition. When such water is present in the polyol composition, when the polyol composition and the polyisocyanate are mixed and reacted, the water and the polyisocyanate react to generate carbon dioxide. In addition, since heat of reaction is generated, the urethanization reaction and isocyanuration reaction can be effectively advanced by the heat, and the compressive strength of the resulting polyurethane foam can be further increased. is there. However, if the content of such water is excessive, the strength is reduced. This is because the urea bond produced by the reaction between water and polyisocyanate increases in the resin, and the polyisocyanate used for the isocyanuration reaction is consumed in the reaction with water, reducing the polyisocyanate in the reaction system. Because. Therefore, the content of water in the polyol composition is desirably 7 parts by mass or less, preferably 5 parts by mass or less, more preferably 3 parts by mass or less with respect to 100 parts by mass of the polyol. In order to sufficiently exhibit the effect of the presence, it is desirable that the content be 0.05 parts by mass or more, preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more. In addition, such water is added and blended as water contained in other blending components such as polyol, in addition to being separately added and blended as a blending component for forming the polyol composition, The water contained by moisture absorption during storage of the polyol composition is also taken into consideration, and the total amount thereof is adjusted so that the ratio is within the above-specified range.

When such a polyol composition and polyisocyanate are mixed and reacted due to the presence of water in such a polyol composition, carbon dioxide is generated by the reaction between the water and the polyisocyanate. Since carbon dioxide also contributes to foaming of the polyurethane, in the present invention, carbon dioxide generated by the reaction of water and polyisocyanate, and carbon dioxide used as the above-mentioned liquefied CO ₂ are used. The above-mentioned halogenated olefin-based blowing agent is present in such a polyol composition so as to have a content of more than 1 mol and 20 mol or less with respect to 1 mol of the total amount.

  If the ratio of the halogenated olefin blowing agent to the total amount of carbon dioxide is too small, such as 1 mol or less, the ratio of carbon dioxide contributing to polyurethane foaming increases, Problems such as reduction in compressive strength and dimensional change rate are caused, and if the proportion of the halogenated olefin-based foaming agent exceeds 20 moles, the core density compared to the skin density is obtained in the resulting polyurethane foam. As a result, the compressive strength decreases, the dimensional change rate increases, and the cost of the polyol composition increases. The halogenated olefin-based blowing agent is preferably used in a ratio of about 2 to 10 moles with respect to 1 mole of the total amount of carbon dioxide.

  By the way, in the present invention, a polyol composition and a polyisocyanate are mixed, reacted in the presence of a catalyst, foamed and cured, thereby forming a rigid polyurethane foam. However, as the catalyst used there, a known catalyst conventionally used in the production of polyurethane foam is appropriately selected and contained in the polyol composition. It is desirable to reduce the amount of the catalyst used because the halogenated olefin blowing agent, particularly hydrochlorofluoroolefin, may be decomposed. In addition, as an amine catalyst, the reaction of polyisocyanate and water is promoted, and the reaction between polyisocyanate and polyol is accelerated, and the amine foaming catalyst having a relatively high foaming activity that generates carbon dioxide at an early stage. There are amine-based resinification catalysts with high resinization activity. Further, the amine-based resinification catalyst is classified into an amine-based urethanization catalyst and an amine-based isocyanurate-forming catalyst. Here, examples of the amine foaming catalyst include pentamethyldiethylenetriamine, bis (dimethylaminoethyl) ether, N, N, N′-trimethylaminoethylethanolamine, and the like. Examples of the amine-based urethanization catalyst include triethylenediamine, N, N, N ′, N′-tetramethylhexamethylenediamine, N-ethylmorpholine, and the like. Examples of amine-based isocyanuration catalysts include tris (dimethylaminopropyl) hexahydrotriazine. The amine-based resinification catalyst is appropriately selected and used according to the type of foam. For example, an amine-based urethanization catalyst or an amine-based isocyanuration catalyst is used alone, or these are used. It is used together.

  In addition, as a non-amine-based resinification catalyst, as a urethanization catalyst, dibutyltin dilaurate, bismuth octylate (bismuth 2-ethylhexylate), bismuth neodecanoate, bismuth neododecanoate, bismuth naphthenate, and the like, naphthene Lead acid etc. can be mentioned. On the other hand, examples of the isocyanuration catalyst include fatty acid alkali metal salts such as quaternary ammonium salts, potassium octylate, and sodium acetate.

  In particular, in the present invention, it is recommended to use a quaternary ammonium salt among the above-mentioned isocyanuration catalysts which are resinification catalysts. By using such a quaternary ammonium salt, isocyanurate can be produced, and thus properties such as compressive strength and dimensional stability can be improved more advantageously.

  Examples of the quaternary ammonium constituting such a quaternary ammonium salt include tetramethylammonium, methyltriethylammonium, ethyltrimethylammonium, propyltrimethylammonium, butyltrimethylammonium, pentyltrimethylammonium, hexyltrimethylammonium, and heptyltrimethyl. Ammonium, octyltrimethylammonium, nonyltrimethylammonium, decyltrimethylammonium, undecyltrimethylammonium, dodecyltrimethylammonium, tridecyltrimethylammonium, tetradecyltrimethylammonium, heptadecyltrimethylammonium, hexadecyltrimethylammonium, heptadecyltrimethylammonium, octade Aliphatic ammonium compounds such as rutrimethylammonium, hydroxyammonium compounds such as (2-hydroxypropyl) trimethylammonium, hydroxyethyltrimethylammonium, trimethylaminoethoxyethanol, 1-methyl-1-azania-4-azabicyclo [2,2, 2] Alicyclic ammonium compounds such as octanium, 1,1-dimethyl-4-methylpiperidinium, 1-methylmorpholinium, 1-methylpiperidinium and the like. Among these, tetramethylammonium, methyltriethylammonium, ethyltrimethylammonium, butyltrimethylammonium, hexyltrimethylammonium, octyltrimethylammonium, decyltrimethylammonium, dodecyltrimethylammonium, Tetradecyltrimethylammonium, hexadecyltrimethylammonium, octadecyltrimethylammonium, (2-hydroxypropyl) trimethylammonium, hydroxyethyltrimethylammonium, 1-methyl-1-azania-4-azabicyclo [2,2,2] octanium, 1, 1-dimethyl-4-methylpiperidinium is preferred.

  Examples of the organic acid group or inorganic acid group constituting the quaternary ammonium salt include, for example, formic acid group, acetic acid group, octylic acid group, oxalic acid group, malonic acid group, succinic acid group, glutaric acid group, adipic acid Group, benzoic acid group, toluic acid group, ethyl benzoic acid group, methyl carbonate group, phenol group, alkylbenzene sulfonic acid group, toluene sulfonic acid group, benzene sulfonic acid group, phosphoric acid ester group and other organic acid groups and halogen groups And inorganic acid groups such as a hydroxyl group, a hydrogen carbonate group, and a carbonate group. Among these, a formic acid group, an acetic acid group, an octylic acid group, a methyl carbonate group, a halogen group, a hydroxyl group, a hydrogen carbonate group, and a carbonate group are preferable because of excellent catalytic activity and industrial availability.

  In addition, as a catalyst which consists of such a quaternary ammonium salt, various things are marketed, for example, U-CAT 18X (product of San Apro), Kaoriza no. 410 (product of Kao Corporation).

  And the usage-amount of the quaternary ammonium salt as this catalyst will be selected in the range of 0.1-15 mass parts with respect to 100 mass parts of the polyol in a polyol composition. When the amount of the quaternary ammonium salt used is less than 0.1 parts by mass, the proportion of the isocyanurate structure (trimer) in the resin skeleton decreases, and the foam becomes soft, so that the compressive strength and dimensional stability are increased. On the other hand, if it exceeds 15 parts by mass, the proportion of the isocyanurate structure (trimer) obtained is difficult to increase, and it is difficult to expect an effect commensurate with the amount added. There are problems such as an increase in the cost of the polyol composition.

  In the present invention, the polyisocyanate which is blended with the above-described polyol composition and reacts with the polyol in the polyol composition to form a polyurethane has two or more isocyanate groups (NCO in the molecule). Group), for example, diphenylmethane diisocyanate, polymethylene polyphenylene polyisocyanate, tolylene diisocyanate, polytolylene triisocyanate, xylylene diisocyanate, naphthalene diisocyanate and other aromatic polyisocyanates, hexamethylene diisocyanate, etc. In addition to alicyclic polyisocyanates such as aliphatic polyisocyanates and isophorone diisocyanates, urethane prepolymers having isocyanate groups at the molecular ends, Isocyanurate modified product of cyanate, can be mentioned carbodiimide modified product or the like. These polyisocyanate compounds may be used alone or in combination of two or more. In general, polymethylene polyphenylene polyisocyanate (crude MDI) is preferably used from the viewpoints of reactivity, economy, and handling properties.

  Furthermore, the blending ratio of the polyisocyanate and the polyol composition described above is changed depending on the type of foam (for example, polyurethane, polyisocyanurate). Generally, the isocyanate group (NCO) of the polyisocyanate and the polyol are used. The NCO / OH index (equivalent ratio) indicating the ratio of the polyol in the composition to the hydroxyl group (OH) is appropriately determined so as to be in the range of about 0.9 to 2.5.

  By the way, in the polyol composition and polyisocyanate according to the present invention, various known materials such as known flame retardants and foam stabilizers are further added to the above-described blended components or contained components as necessary. It is also possible to appropriately select and mix the auxiliary agent.

And, when the polyol composition and polyisocyanate thus obtained are reacted in the presence of a catalyst and foamed and cured, various known methods for producing polyurethane foam can be employed, For example, by applying a mixture of these polyol composition and polyisocyanate on the face material, laminating continuous foaming method that foams and cures in the form of a plate, in a space part that requires heat insulation performance such as an electric refrigerator, Injection foaming method in which foam is injected and filled into the honeycomb structure of a high-strength board, and foaming / curing is performed, or spray foaming is performed by spraying to a predetermined adherend (structure) from a spray gun head of an on-site foaming machine. The desired polyurethane foam is formed by foaming and curing by the method. It is suitably applied to a spray foaming method induced to foam-in-place in the lower environmental temperature (ambient temperature). Application to such a field spray foaming method advantageously realizes thinning and low density of the skin layer according to the present invention, and the difference between the total density of the foam and the core density is 1 to 12 kg / m ^3. A polyurethane foam having properties and excellent properties such as dimensional stability is advantageously obtained.

  Hereinafter, some examples of the present invention will be shown, and the features of the present invention will be more specifically clarified by comparing with comparative examples. However, the present invention will be described by describing such examples. It goes without saying that it is not subject to any restrictions. In addition to the following examples, the present invention includes various modifications based on the knowledge of those skilled in the art without departing from the spirit of the present invention, in addition to the specific description described above. It should be understood that modifications, improvements, etc. can be made. In addition,% and part shown below are all based on mass.

-Preparation of polyol composition-
Prepare MAXIMOL RDK-133 (product of Kawasaki Kasei Co., Ltd.) which is an aromatic polyester polyol as polyol, and prepare Tegostarb B8450 (product of Evonik Degussa Japan Co., Ltd.) as a silicone foam stabilizer. WSFR-TCPP (product of Wanshan), which is tris (1-chloro-2-propyl) phosphate, was prepared as a flame retardant. In addition, as a catalyst, catalyst A: PACCAT 25 (product of Nippon Chemical Industry Co., Ltd.), which is a metal-based resinification catalyst, and catalyst B: U-CAT 18X (SUN-APRO), which is a quaternary ammonium salt-based isocyanurate catalyst Product) and catalyst C: Kaoriser No. 410 (product of Kao Corporation) and 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz: product of Dupont) and 1 as halogenated olefin-based blowing agents. -Chloro-3,3,3-trifluoropropene (HCFO-1233zd: Honeywell product) was prepared.

  The polyol, silicone foam stabilizer, flame retardant, catalyst, and halogenated olefin foaming agent were mixed uniformly with water at various blending ratios shown in Tables 1 and 2 below. Various polyol compositions according to 1 to 8 and Comparative Examples 1 to 6 were prepared.

-Preparation of polyisocyanate-
Crude MDI (Millionate MR-100: product of Tosoh Corporation) was prepared as a polyisocyanate.

-Production of polyurethane foam-
Using the polyol composition prepared above and polyisocyanate (crude MDI), the liquid composition having the ratios shown in Tables 1 and 2 was first added to the polyol composition by an in-situ foam blowing apparatus equipped with a liquefied carbon dioxide supply apparatus. After supplying and mixing carbon dioxide, the obtained polyol composition containing liquid carbon dioxide was contact-mixed in a ratio of 1: 1 by volume with respect to polyisocyanate, and in accordance with JIS-A-9526. Then, under the conditions of 23 ± 5 ° C. and relative humidity of 80% or less, in the booth of 2 m × 2 m × 1.5 m, the plywood surface, which is a casing, is sprayed once and two times of top blowing. Then, by foaming and curing, the lower spray layer has a thickness of 5 mm and the two upper spray layers have a thickness of 30 mm or less, respectively, and various types according to Examples 1 to 8 and Comparative Examples 1 to 6 A foam layer made of rigid polyurethane foam was formed.

  The various polyurethane foams thus obtained were used to measure their compressive strength, dimensional change rate, overall density, and core density, and the results obtained are shown in Tables 1 and 2 below. Indicated.

  In addition, evaluation of compressive strength evaluated the internal skin layer (skin layer by the 1st top-blowing) in it in the size of 50 mm x 50 mm x 50 mm as a test piece from the foamed layer formed on the plywood. It cut out so that it might exist, It implemented by measuring 10% compressive strength using a universal testing machine according to JIS-K-7220 using the obtained test piece. In addition, the evaluation of the rate of dimensional change is that a foam layer formed on the surface of the plywood has a size of 100 mm × 100 mm × 25 mm so that one internal skin layer (skin layer formed by the first top spray) exists therein. The test piece was cut out and measured by measuring the dimensional change after leaving it in a constant temperature and humidity chamber kept at a temperature of 70 ° C. and a humidity of 95% for 48 hours.

  Further, the evaluation of the overall density and the core density of the foam was performed as follows. That is, the thickness of the polyurethane foam having a skin layer formed by spraying on a 910 mm × 910 mm plywood was measured at 13 points positioned at approximately equal distances in the vertical and horizontal directions. While calculating | requiring the volume of a foam, the mass of the plywood which sprayed the polyurethane foam further is measured, and the mass of a polyurethane foam is calculated | required by subtracting the mass of the plywood measured beforehand, and a total density is calculated. Also, the surface skin layer (skin layer formed by the second top blowing) is removed from the foamed layer formed on the plywood, the core layer is revealed, and a polyurethane foam of 200 mm × 200 mm × 25 mm is cut out and its mass To calculate the core density.

  As is clear from the results of Table 1, all of the polyurethane foams obtained in Examples 1 to 8 according to the present invention have excellent compressive strength and a small dimensional change rate. It can be seen that the difference between the density and the core density is also small and has good foam properties.

On the other hand, as shown in the results of Table 2, in Comparative Example 1 in which liquid CO ₂ was not blended with the polyol composition, the compressive strength was low, the dimensional change rate was increased, the overall density and the core The difference from the density also increased, and it was confirmed that the foam physical properties were inferior. In the case of Comparative Example 2 and Comparative Example 3 where the amount of liquid CO ₂ is large, the desired foam cannot be obtained, and the molar ratio of the foaming agent and liquid CO ₂ is the present invention. In Comparative Example 4 and Comparative Example 5 that are outside the range, it was recognized that the polyurethane foam had insufficient compression strength and a large dimensional change rate. Furthermore, in Comparative Example 6 in which no halogenated olefin-based foaming agent was used, it was confirmed that the rate of dimensional change was large, the difference between the overall density and the core density was large, and the foam physical properties were inferior.

Claims (3)

When producing a polyurethane foam by mixing and reacting a polyol composition and a polyisocyanate in the presence of a catalyst, and foaming and curing,
In a ratio of 0.1 to 7 parts by mass with respect to 100 parts by mass of the polyol in the polyol composition, supercritical, subcritical or liquid carbon dioxide is added to the polyol composition or the polyisocyanate, and While the polyol composition contains water in a ratio of 0.05 to 7 parts by mass with respect to 100 parts by mass of the polyol, the polyol composition is selected from the group consisting of hydrofluoroolefins and hydrochlorofluoroolefins. Containing one or more foaming agents, and such foaming agents are generated by reaction of the polyisocyanate and the water during the production of the supercritical, subcritical or liquid carbon dioxide and the polyurethane foam. In a ratio of more than 1 mole and 20 moles or less with respect to 1 mole of the total amount of carbon dioxide Te, and allowed to be present in the polyol composition, method for producing a polyurethane foam, characterized in that to perform the reaction.   The method for producing a polyurethane foam according to claim 1, wherein a quaternary ammonium salt is contained in the polyol composition as the catalyst. The method for producing a polyurethane foam according to claim 1 or 2, wherein the polyol composition and the polyisocyanate are sprayed onto a surface of a predetermined structure to be foamed and cured.