JP5441790B2 - Rigid polyurethane foam and method for producing the same - Google Patents

Description

  The present invention relates to a rigid polyurethane foam excellent in dimensional stability while having a low density and a high independent foaming rate, and a method for producing the same.

  Rigid polyurethane foam is excellent in heat insulation, moldability, self-adhesiveness, etc., and is used as various heat insulating materials for buildings such as houses and refrigerator-freezer warehouses, and vending machines and refrigerators. The rigid polyurethane foam is obtained by reacting a polyol and polyisocyanate in the presence of a catalyst, a foam stabilizer, and a foaming agent. Conventionally, hydrochlorofluorocarbon (HCFC) has been used as a foaming agent for producing rigid polyurethane foam, which can easily obtain a foam with low density, good dimensional stability, and high closed cell ratio. HCFCs are now prohibited from being used because they cause environmental problems that destroy the ozone layer.

  In recent years, hydrofluorocarbons (HFC), hydrocarbons such as pentane (HC), water, and the like have been used as foaming agents for producing rigid polyurethane foams in place of the above HCFCs. A method of producing a rigid polyurethane foam using an agent has been proposed (Patent Document 1, Patent Document 2).

JP 2009-108160 A JP 2007-197499 A

  However, the rigid polyurethane foam obtained by using a foaming agent such as water, HFC, HC, etc. has a problem that it is inferior in dimensional stability as compared with the rigid polyurethane foam obtained by using HCFC. In order to improve the dimensional stability of the foam, for example, there is a method in which the cells in the foam are made into open cells. However, this method has a problem that the closed cell ratio is lowered and the heat insulation is deteriorated. On the other hand, if the density of the rigid polyurethane foam is increased, the dimensional stability is improved. However, as in the case where HCFC is used as a foaming agent, the rigid polyurethane foam has a low density, a high closed cell ratio, and excellent dimensional stability. It was difficult to obtain a polyurethane foam.

  The present invention has been made in view of the above-mentioned problems of the prior art, and is a rigid polyurethane foam using water, HFC, HC, carbon dioxide or the like as a foaming agent, and has a low content as in the case where HCFC is used as a foaming agent. An object of the present invention is to provide a rigid polyurethane foam having good dimensional stability even at a density and excellent heat insulation properties having a high closed cell ratio. Another object of the present invention is to provide a method for producing a rigid polyurethane foam that uses water, HFC, HC, carbon dioxide or the like as a foaming agent, has excellent dimensional stability even at low density, and has a high closed cell ratio. And

That is, the present invention
(1) Polyol and polyisocyanate are made of one, two or more blowing agents selected from water, hydrofluorocarbon, hydrocarbon, carbon dioxide, catalyst, and silicone having a weight average molecular weight of 4000 to 6000 (PEG conversion value). system compound, the weight average molecular weight 500-2000 rigid polyurethane Form of a silicone compound obtained by reacting in the presence of at least including HLB7 following foam stabilizer (PEG converted value),
(2) The rigid polyurethane foam according to the above (1), having a density of 20 to 40 kg / m ³ , a closed cell ratio of 60 to 100%, and a dimensional change rate of 10% or less,
(3) Polyol and polyisocyanate are silicones having one or more foaming agents selected from water, hydrofluorocarbons, hydrocarbons and carbon dioxide, catalysts, and weight average molecular weight (PEG conversion value) of 4000 to 6000. A method for producing a rigid polyurethane foam, characterized by reacting in the presence of a foam stabilizer having an HLB of 7 or less, comprising at least a silicone compound having a weight average molecular weight of 500 to 2000 (PEG conversion value),
Is a summary.

  The rigid polyurethane foam of the present invention is obtained by using water, HFC, HC, carbon dioxide as a foaming agent, and is excellent in dimensional stability even at low density, and has a high closed cell ratio, and thus has heat insulation properties. Etc. Further, according to the method for producing a rigid polyurethane foam of the present invention, it has been difficult to obtain conventionally when water, HFC, or carbon dioxide is used as a foaming agent, and it has low density, excellent dimensional stability, and independent. There is an effect that a rigid polyurethane foam having a high cell ratio can be obtained with certainty.

  The rigid polyurethane foam of the present invention includes rigid polyurethane foams such as urethane-modified rigid polyisocyanurate foams, rigid polyisocyanurate foams, and other rigid foams in addition to so-called rigid polyurethane foams. Hereinafter, although a rigid polyurethane foam is demonstrated for convenience, this invention is not limited to this.

  The rigid polyurethane foam of the present invention comprises a polyisocyanate and a polyol in the presence of a catalyst, a foam stabilizer, and a foaming agent (at least one selected from water, HFC, HC, carbon dioxide) or a continuous process or a discontinuous process. It can be made to react by such as.

  Examples of the HFC used as the foaming agent include 1,1,1,3,3-pentafluoropropane (HFC245fa), 1,1,1,3,3-pentafluorobutane (HFC365mfc), and the like. Examples of HC include normal pentane, isopentane, cyclopentane, isobutane and the like. Examples of carbon dioxide include carbon dioxide in a liquid state, a subcritical state, and a supercritical state. Water, HFC, HC, and carbon dioxide can be used alone or in combination of two or more. The amount of the blowing agent used is preferably 5 to 40 parts by weight per 100 parts by weight of polyol.

The rigid polyurethane foam of the present invention has a density of 20 to 40 kg / m ³ , a closed cell rate of 60 to 100%, and a dimensional change rate of 10% or less, but a density of 22 to 32 kg / m ³ and a closed cell rate. 70 to 100% and a dimensional change rate of 5% or less are preferable.

  The foam stabilizer used for obtaining the rigid urethane foam of the present invention includes at least a silicone compound having a weight average molecular weight (PEG conversion value) of 4000 to 6000 and a silicone having a weight average molecular weight of 500 to 2000 (PEG conversion value). A foam stabilizer having an HLB of 7 or less is used. The foam stabilizer used in the present invention preferably contains 70% by weight or more of the silicone compound having a weight average molecular weight of 4000 to 6000 and 3 to 30% by weight of a silicone compound having a weight average molecular weight of 500 to 2,000. It preferably contains 80 to 95% by weight of a silicone compound having a weight average molecular weight of 4000 to 6000 and 5 to 20% by weight of a silicone compound having a weight average molecular weight of 500 to 2000. The foam stabilizer may contain one or more kinds of silicone compounds having a weight average molecular weight of 4000 to 6000 and one or more kinds of silicone compounds having a weight average molecular weight of 500 to 2,000, Further, it may contain a silicone compound having a weight average molecular weight of less than 500, a silicone compound having a weight average molecular weight of more than 2000 to less than 4000, a silicone compound having a weight average molecular weight of more than 6000, and the like. The foam stabilizer preferably has a surface tension of 20 to 26 mN / m.

  Specific examples of the foam stabilizer used in the present invention include SZ-1328, SZ-1346E, and SZ-1333 (all of which are model numbers of foam stabilizers manufactured by Toray Dow Corning Co., Ltd.). One or more foaming agents can be used in combination. The amount of the foam stabilizer used is preferably 0.1 to 5 parts by weight per 100 parts by weight of the polyol compound. Along with the above-mentioned foam stabilizer, commercially available foam stabilizers for rigid polyurethane foam, for example, SF-2937F, SF-2938F, SZ-1671, SZ-1710, SH-193, SF-2936F, SZ-1642 , SZ-1720 (all are model numbers of a foam stabilizer manufactured by Toray Dow Corning Co., Ltd.), or B8481, B8443, B8465, B8486, B8466, B8450 (all are model numbers of foam stabilizers manufactured by Evonik Degussa Japan Co., Ltd.) Etc. can also be used together.

  In the present invention, polyester polyol and polyether polyol can be used as the polyol, and these can be used alone or in combination of two or more. Examples of the polyester polyol include a polyol formed by condensing a polyhydric alcohol with a polyvalent carboxylic acid, and a polyol formed by cyclic ester ring-opening polymerization. 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 polyols composed of these anhydrides. On the other hand, examples of the polyhydric alcohol include ethylene glycol, propylene glycol, glycerin, trimethylol propane, pentaerythritol, sorbitol, shoelace, and bisphenol A. As the polyester polyol, a polyester polyol having an aromatic ring is particularly preferable. The hydroxyl value of the polyester polyol is not particularly limited, but is preferably 100 to 400 mgKOH / g.

  Examples of polyether polyols include alcohols such as aliphatic alcohols, aromatic alcohols, and polyhydric alcohols; aliphatic amines such as ethanolamine, diethanolamine, triethanolamine, and ethylenediamine; aromatics such as toluenediamine and methylenedianiline. Examples of amine polyols include polyether polyols obtained by addition polymerization of one or more alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide in Mannich condensation products. It can use individually or in combination of 2 or more types as appropriate. As the polyether polyol, an aromatic polyether polyol is particularly preferable because it lowers the thermal conductivity. The hydroxyl value of the polyether polyol is not particularly limited, but is preferably 300 to 800 mgKOH / g. Further, a polymer polyol in which a polymer component such as vinyl acetate, polyacrylonitrile, or polyacrylonitrile / styrene copolymer is dispersed in a polyether polyol may be used. In particular, a polymer polyol in which vinyl acetate or a polyacrylonitrile / styrene copolymer is dispersed in a polyether polyol is preferably used.

  Examples of the polyisocyanate to be reacted with the above-mentioned polyol include diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, etc .; these modified polyisocyanates, that is, products obtained by partial chemical reaction of polyisocyanate, for example, esters, urea, burettes, And polyisocyanates containing groups such as allophanate, carbodiimide, isocyanurate, and urethane. These polyisocyanates can be used alone or in combination of two or more.

  The amount of the polyisocyanate used is preferably such that the isocyanate index represented by the following formula (1) is 50 to 300, more preferably 100 to 250.

(Equation 1)
Isocyanate index = NCO group / active hydrogen of polyol × 100 (1)

  As the catalyst used for reacting the polyol and the polyisocyanate, conventionally used amine catalysts, metal catalysts, and the like can be used. Examples of the amine catalyst include N, N, N ′, N′-tetramethylhexanediamine, N, N, N ′, N′-tetramethylpropanediamine, N, N, N ′, N ″, N ′. '-Pentamethyldiethylenetriamine, N, N, N', N'-tetramethylethylenediamine, N, N, -dimethylbenzylamine, N-methylmorpholine, N-ethylmorpholine, triethylenediamine, N, N ', N '-Trimethylaminoethylpiperazine, N, N-dimethylcyclohexylamine, N, N ′, N ″ -tris (3-dimethylaminopropyl) hexahydro-s-triazine, bis (dimethylaminoethyl) ether, N, N— Aminoethoxyethanol, N, N-dimethylaminohexanol, tetramethylhexanediamine, 1-methyl Imidazole, 1-isobutyl-2-methylimidazole and the like can be used. Examples of the metal catalyst that can be used include stannous octoate; dibutyltin dilaurate; lead octylate; potassium salts such as potassium acetate and potassium octylate. In addition to these amine catalysts and metal catalysts, quaternary ammonium salts of fatty acids such as formic acid and acetic acid can also be used. Each of the above catalysts may be used alone or in combination of two or more. In the present invention, the amount of the catalyst used is preferably about 0.1 to 15 parts by weight per 100 parts by weight of polyol.

  In the production of the rigid polyurethane foam of the present invention, in addition to the polyol, polyisocyanate, catalyst, foam stabilizer, and foaming agent, a hardener such as a compatibilizing agent, a thinning agent, a colorant, and a stabilizer, if necessary. Additives commonly used in the production of polyurethane foams can be used.

  The rigid polyurethane foam of the present invention reacts a polyol and a polyisocyanate in the presence of one or more foaming agents, catalysts, and foam stabilizers selected from water, hydrofluorocarbons, hydrocarbons, and carbon dioxide. The high-pressure and low-pressure hard polyurethane foaming machines generally used are used for the production thereof, for example, polyisocyanate, polyol, foaming agent, catalyst, foam stabilizer and other auxiliary agents. It is possible to use a foaming method in which the mixture of is continuously or discontinuously mixed at a constant ratio.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Examples 1-8, Comparative Example 1
The raw materials used in Examples and Comparative Examples are shown below.
[Raw materials]
Polyisocyanate Polymeric diphenylmethane diisocyanate (manufactured by Nippon Polyurethane Co., Ltd .: MR200: NCO content 31%)

Polyol polyol A: Polyester polyol polyol B having a hydroxyl value of 315 mgKOH / g using phthalic anhydride as an initiator B: Polyether polyol polyol C having a hydroxyl value of 360 mgKOH / g using toluenediamine as an initiator C: In the polyol using Mannich as an initiator Polyether polyol having a hydroxyl value of 300 mgKOH / g in which a vinyl acetate compound is dispersed in

Foam stabilizer Foam stabilizer A: Foam stabilizer with properties shown in Table 1

Foam stabilizer B: Foam stabilizer whose properties are shown in Table 2

Catalyst: Tris- (dimethylaminopropyl) -hexatriazine (manufactured by Air Products: Polycat 41)

Flame retardant: Trischloropropyl phosphate (manufactured by Daihachi Chemical Co., Ltd .: TMCPP)

Foaming agent:
Foaming agent A: HFC365mfc
Blowing agent B: Water blowing agent C: Cyclopentane

[Form production method]
The mixture having the composition shown in Table 3 was stirred at 3400 rpm for 3 seconds using a hand mixer, and then freely foamed in a wooden box of 250 mm × 150 mm × 300 mm to obtain a rigid polyurethane foam. A mixture having the same composition was stirred at 3400 rpm for 3 seconds using a hand mixer, and then foamed at a pack rate of 120% in a 300 mm × 300 mm × 30 mm mold to produce a rigid polyurethane foam. In addition, the polyisocyanate and the polyol were blended so that the liquid temperature was 25 ° C. and the isocyanate index was 150. Moreover, the unit of each numerical value of polyol AB shown in Table 3, foam stabilizer AB, foaming agent AC, a catalyst, a flame retardant, and polyisocyanate is a weight part.

  About the rigid polyurethane foam obtained by the said manufacturing method, the density, the closed cell rate, the heat conductivity, and the dimensional change were evaluated with the following method. The results are shown in Table 3.

〔Evaluation method〕
Density (kg / m ³ ): A test piece of 100 mm × 100 mm × 100 mm was cut out from a rigid polyurethane foam obtained by free foaming in a wooden box, and the density of the test piece was measured according to JIS A9511.

Closed cell ratio (%): A test piece of 30 mm × 30 mm × 25 mm was cut out from a rigid polyurethane foam obtained by foaming in a mold, and the closed cell ratio of the test piece was measured in accordance with ASTM D2856.

Thermal conductivity (W / mK): A test piece of 200 mm × 200 mm × 25 mm was cut out from a rigid polyurethane foam obtained by free foaming in a wooden box, and the thermal conductivity of the test piece is shown in JIS A1412. Thus, measurement was performed at an average temperature of 23 ° C. using an auto λHC-074 manufactured by Eihiro Seiki Co., Ltd.

Dimensional change: A test piece of 150 mm × 100 mm × 100 mm was cut out from a rigid polyurethane foam obtained by free foaming in a wooden box, and the test piece was left at −20 ° C. for 72 hours or more and left at 120 ° C. for 6 hours or more. Investigate the deformation state of the test piece when
○: The dimensional change rate of the foam is 10% or less.
X: The dimensional change rate of the foam exceeds 10%.
It was evaluated.

  In Examples 1 to 8, a rigid polyurethane foam having normal foaming behavior, excellent foam appearance, low density, high closed cell ratio and no dimensional change was obtained. In Comparative Example 1, the foaming behavior was Although a normal, excellent foam appearance, low density and high closed cell ratio rigid polyurethane foam was obtained, the foam had a large dimensional change and contracted after the foam was produced.

Claims (3)

A polyol and a polyisocyanate, one or more foaming agents selected from water, hydrofluorocarbons, hydrocarbons and carbon dioxide, a catalyst, and a silicone compound having a weight average molecular weight of 4000 to 6000 (PEG conversion value) , weight average molecular weight 500-2000 rigid polyurethane Form of a silicone compound obtained by reacting in the presence of at least including HLB7 following foam stabilizer (PEG converted value). Density is 20-40kg / m ³ The rigid polyurethane foam according to claim 1, having a closed cell ratio of 60 to 100% and a dimensional change rate of 10% or less. A polyol and a polyisocyanate, one or more foaming agents selected from water, hydrofluorocarbon, hydrocarbon, carbon dioxide, a catalyst, and a silicone compound having a weight average molecular weight (PEG conversion value) of 4000 to 6000; A method for producing a rigid polyurethane foam, comprising reacting in the presence of a foam stabilizer of HLB 7 or less containing at least a silicone compound having a weight average molecular weight of 500 to 2000 (PEG conversion value).