JP2008208382A - Method for producing rigid polyurethane foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a rigid polyurethane foam having good surface appearance as to be suppressed in void development despite using a low-boiling foaming agent. <P>SOLUTION: The method for producing a rigid polyurethane foam comprises reacting a polyol compound with an isocyanate compound in the presence of the foaming agent, a foam stabilizer and a catalyst, wherein an organic compound having ≤20°C in boiling point is used as at least part of the foaming agent, and a polyol mixture containing 0.5-30% by mass of a polyol (A) is used as a polyol compound, in which the polyol (A) is a polyoxyalkylene polyol having ≥40 mgKOH/g to ≤70 mgKOH/g in hydroxy value, 2.8-5.2 in hydroxy number, and containing 5-40% by mass of oxyethylene groups based on the whole polyol (A). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a rigid polyurethane foam (hereinafter referred to as a rigid foam), and more particularly, to a production method for improving the foam appearance when a low boiling point foaming agent is used.

  As a method for producing a rigid foam molded body covered with a face material, a production method in which a foaming stock solution composition is injected between the face materials from a foaming machine is usually employed. As the foaming machine, a high-pressure foaming machine that collides and mixes the foamed stock solution composition at a high pressure and a low-pressure foaming machine that mixes the foamed stock solution composition via a mixer at a relatively low pressure are used. The injected undiluted liquid composition foams while polymerizing, fills the space between the face materials, cures and self-adheres with the face material to form a heat insulating structure.

One method for producing rigid foam (foaming method) is to use a foaming method having a boiling point near room temperature and a foaming agent that is gaseous (ie, low boiling point) at room temperature. This is called foaming. The advantages of floss foaming are that the filling property after injection is improved, and that the pressure at the time of foaming is low and large-scale clamping facilities are not required. Thus, the proposal regarding manufacturing a rigid foam using a low boiling-point foaming agent is made (for example, refer patent documents 1-3).
JP-A-2-235882 JP-A-5-239251 Japanese Patent Laid-Open No. 3-7738

  However, in this froth foaming, generation of voids (also referred to as froth voids) is a problem because this low boiling point foaming agent is used. In particular, since there is a tendency to reduce the thickness of the face material for cost reduction and weight reduction in recent years, there is a problem that slight irregularities of the rigid foam appear on the surface of the face material and impair the appearance. In addition, since the void portion has a weak adhesive force between the foam and the face material, there is a problem in that peeling of the face material and the foam occurs starting from the void when vibration or stress is applied.

  Further, it has been proposed to use a fluorinated hydrocarbon (hereinafter referred to as HFC) or a hydrocarbon as a foaming agent that does not cause destruction of the ozone layer. As HFC, 1,1,1,2-tetrafluoroethane (boiling point: −26 ° C.) (hereinafter referred to as HFC-134a), 1,1,1,3,3-pentafluoropropane (boiling point: 15 ° C.) (Hereinafter referred to as HFC-245fa) and 1,1,1,3,3-pentafluorobutane (boiling point: 40 ° C.) (hereinafter referred to as HFC-365mfc), etc. Boiling point: 49 ° C), hexane (boiling point: 69 ° C), cyclohexane (boiling point: 80 ° C). Of these, froth voids are likely to occur when a gaseous compound such as HFC-134a or HFC-245fa is used as a foaming agent for rigid foam. Furthermore, bubbles are more fragile during the foaming process than conventional foaming agents, tend to have more voids, and become larger.

  In patent document 1, it is proposed to use HFC-245fa as a foaming agent for producing a polyurethane foam. Patent Document 2 proposes a method for producing a rigid foam using both HFC-245fa and water. Patent Document 3 proposes to use HFC-134a as a foaming agent. However, these proposals do not mention improvement of the floss void.

  The present invention solves the above problems, and provides a method for producing a rigid foam having a good appearance without fear of destruction of the ozone layer.

  That is, the present invention relates to a method for producing a rigid polyurethane foam by reacting a polyol compound and an isocyanate compound in the presence of a foaming agent, a foam stabilizer and a catalyst, and an organic compound having a boiling point of 20 ° C. or less as at least a part of the foaming agent. A method for producing a rigid polyurethane foam comprising using a compound and a polyol mixture containing 0.5 to 30% by mass of the following polyol (A) as a polyol compound. However, the polyol (A) has a hydroxyl value of 40 mgKOH / g or more and 70 mgKOH / g or less, a hydroxyl number of 2.8 to 5.2, and an oxyethylene group of 5 to 5 with respect to the entire polyol (A). It is a polyoxyalkylene polyol containing 40% by mass.

  The present invention prevents the generation of froth voids resulting from a low boiling point foaming agent by improving the compatibility between the polyol compound and the foaming agent and improving the compatibility between the polyol compound and the isocyanate compound. That is, by using a specific long-chain polyoxyalkylene polyol, the compatibility of each raw material composition can be improved, and the stability of the foam in the foaming process can be improved.

  Moreover, it is preferable that 1,1,1,3,3-pentafluoropropane and / or 1,1,1,2-tetrafluoroethane is included as an organic compound having a boiling point of 20 ° C. or lower used as the blowing agent. In particular, a fluorinated hydrocarbon mixture comprising 1,1,1,3,3-pentafluoropropane and 1,1,1,2-tetrafluoroethane as an organic compound having a boiling point of 20 ° C. or less used as the blowing agent. The proportion of 1,1,1,3,3-pentafluoropropane in the fluorinated hydrocarbon mixture is preferably 1 to 99% by mass.

  Moreover, it is preferable to use 0.1-5 mass parts of the following foam stabilizer (F) as said foam stabilizer with respect to 100 mass parts of the whole polyol compound. However, the foam stabilizer (F) is a silicone foam stabilizer in which a polyoxyalkylene chain is grafted to a polysiloxane chain, the chain length of the polysiloxane chain is 2000 to 3000, and the polyoxyalkylene chain The chain length is 1000 to 2000, the number of grafts is 1.5 to 2.5, the polyoxyalkylene chain end does not have a hydroxyl group, and the ratio of the polysiloxane chain to the total foam stabilizer is 30 to 30. It is a silicone foam stabilizer that is 50% by mass.

  As the foaming device, it is preferable to use a simple foaming device that operates only by pressure operation of the gas supplied from the gas cylinder.

  The present invention has an effect that a foamed synthetic resin having a good surface appearance of the panel can be produced without using a chlorine-containing foaming agent that may destroy the ozone layer.

(Polyol)
This invention is a manufacturing method of the rigid foam characterized by using the polyol mixture which contains 0.5-30 mass% of following polyols (A) as a polyol compound. However, the polyol (A) has a hydroxyl value of 40 mgKOH / g or more and 70 mgKOH / g or less, a hydroxyl number of 2.8 to 5.2, and an oxyethylene group of 5 to the whole polyol (A). It is a polyoxyalkylene polyol containing -40% by mass.

The polyol (A) has a hydroxyl value of less than 200 mgKOH / g, preferably 170 mgKOH / g or less, more preferably 100 mgKOH / g or less, and particularly preferably 70 mgKOH / g or less. The lower limit of the hydroxyl value is not particularly limited, but is preferably 30 mgKOH / g or more, more preferably 40 mgKOH / g or more, and particularly preferably 50 mgKOH / g or more. When the hydroxyl value is 200 mgKOH / g or more, that is, when the molecular weight is low, the compatibility of each raw material composition is hardly improved, which is not preferable.
In the present invention, the hydroxyl value is 40 mgKOH / g or more and 70 mgKOH / g or less.

  The polyol (A) is a polyoxyalkylene polyol obtained by subjecting an alkylene oxide to ring-opening addition polymerization to an initiator. Examples of the initiator include polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, tripropylene glycol, glycerin, trimethylolpropane, pentaerythritol, and saccharides; alkanolamines such as diethanolamine and triethanolamine, Or a small amount of these alkylene oxide adducts.

  As the alkylene oxide to be subjected to ring-opening addition polymerization to the initiator, ethylene oxide and an alkylene oxide having 3 or more carbon atoms are used in combination. Examples of the alkylene oxide having 3 or more carbon atoms include propylene oxide, 1,2-epoxybutane, 2,3-epoxybutane, and styrene oxide, with propylene oxide being preferred. Ethylene oxide and alkylene oxide having 3 or more carbon atoms may be sequentially added to the initiator, or a mixture of ethylene oxide and alkylene oxide having 3 or more carbon atoms may be added. When this mixture is added, a random addition structure is obtained in which ethylene oxide and an alkylene oxide having 3 or more carbon atoms are randomly added.

  The polyol (A) has an oxyethylene group derived from the above-mentioned ethylene oxide, and the proportion thereof is 5 to 40% by mass with respect to the entire polyol (A), preferably 10 to 35% by mass, 10-20 mass% is more preferable. Even if the ratio of the oxyethylene group is less than 5% by mass or more than 40% by mass, the compatibility of each raw material composition is hardly improved, which is not preferable.

Moreover, 2-8 are preferable and, as for the number of hydroxyl groups of a polyol (A), 2.8-5.2 are more preferable. However, the number of hydroxyl groups means the average value of the number of active hydrogens in the initiator. If the number of hydroxyl groups is less than 2, the hardness of the rigid foam tends to be insufficient, and if the number of hydroxyl groups exceeds 8, the dimensional stability tends to deteriorate, which is not preferable.
In the present invention, the number of hydroxyl groups is 2.8 to 5.2.

  In the present invention, a polyol mixture containing the polyol (A) is used as the polyol compound. Although the ratio of a polyol (A) is 0.5-30 mass% with respect to the whole polyol mixture, 1-20 mass% is preferable. When this mixing ratio is less than 0.5% by mass, the compatibility of each raw material composition is difficult to improve, and when it exceeds 30% by mass, the hardness of the resulting foam tends to be insufficient, and the viscosity of the raw material composition is low. It becomes high and the moldability tends to deteriorate, and neither is preferable.

  In the present invention, as the polyol other than the polyol (A) used as the polyol mixture, a polyol usually used for a rigid foam may be used, and an active hydrogen compound other than the polyol may be included. Examples of the polyol used in the normal rigid foam include polyether polyols (polyoxyalkylene polyols), polyester polyols, polyhydric alcohols, and polyhydric phenols. Among these, one or more of them are used. It is preferable to adopt. The hydroxyl value of the polyol usually used in the rigid foam is preferably 200 to 1000 mgKOH / g, more preferably 200 to 800 mgKOH / g, and particularly preferably 300 to 600 mgKOH / g.

  The polyether polyols, like the polyol (A), are polyoxyalkylene polyols obtained by ring-opening addition polymerization of an alkylene oxide to an initiator, but have a higher hydroxyl value (low molecular weight) than the polyol (A). Is. The same initiator as the polyol (A) is used as the initiator. Examples of the alkylene oxide include ethylene oxide, propylene oxide, 1,2-epoxybutane, 2,3-epoxybutane, and styrene oxide. Propylene oxide alone or a combination of ethylene oxide and propylene oxide is preferable. Examples of the polyester polyols include polyols based on polyhydric alcohol-polycarboxylic acid condensation, and cyclic ester ring-opening polymerization.

  As said polyhydric alcohol, what was mentioned as an initiator of a polyol (A) is employable. Examples of the polyhydric phenols include a resol-type initial condensate obtained by condensation-bonding phenols with an excess of formaldehyde in the presence of an alkali catalyst, and a benzylic compound that is reacted in a non-aqueous system when the resol-type initial condensate is synthesized. And a novolak type initial condensate obtained by reacting excess phenols with formaldehyde in the presence of an acid catalyst. The molecular weight of these initial condensates is preferably about 200 to 10,000. In the above, phenols include phenol, cresol, bisphenol A, resorcinol, and the formaldehydes include formalin and paraformaldehyde.

  Moreover, polyamine etc. are mentioned as active hydrogen compounds other than the said polyol. In addition, as the polyol compound in the present invention, a polymer-dispersed polyol containing polymer fine particles may be used. The polymer-dispersed polyol is a dispersion system in which polymer fine particles (dispersoid) are stably dispersed in a base polyol (dispersion medium).

(Foaming agent)
In the present invention, an organic compound having a boiling point of 20 ° C. or lower is used as at least a part of the foaming agent. By using the polyol (A), even if a gaseous foaming agent is used at room temperature, it is possible to produce a rigid foam having a good appearance with suppressed froth voids. Use of a gaseous foaming agent at room temperature is preferable in terms of good filling properties and low foaming pressure. As these foaming agents, it is preferable to use a compound containing no chlorine from the viewpoint of protecting the ozone layer. Moreover, although an organic compound having a boiling point higher than 20 ° C. may be used in combination as the foaming agent, it is preferable not to use it together. In addition to the above compounds, air, nitrogen, carbon dioxide and other inert gases and water can be used in combination as the foaming agent, and it is particularly preferable to use water in combination.

Examples of the organic compound having a boiling point of 20 ° C. or less used as the foaming agent include the following HFCs, perfluoro compounds, and hydrocarbons. A plurality of these may be used in combination, but it is preferable to use only HFC (one or a mixture of two or more). The HFC, _{CH 2 F} 2 (boiling _{point: -52 ℃), CF 3 CHF} 2 ( boiling _{point: -49 ℃), CF 3 CH} 2 F (HFC-134a, boiling _{point: -27 ℃), CF 3 CH} 3 ( Boiling point: −48 ° C.), CHF ₂ CH ₃ (boiling point: −25 ° C.), CF ₃ CF ₂ CHF ₂ (boiling point: −16 ° C.), CF ₃ CHFCF ₃ (boiling point: −15 ° C.), CF ₃ CF ₂ CH ₂ F (boiling point: 1 ° C.), CF ₃ CHFCHF ₂ (boiling point: 7 ° C.), CF ₃ CH ₂ CF ₃ (boiling point: −1 ° C.), CF ₃ CF ₂ CH ₃ (boiling point: −18 ° C.), CF ₃ CHFCH ₂ F (boiling point: 17 ° C.), CF ₃ CH ₂ CHF ₂ (HFC-245fa, boiling point: 15 ° C.), CF ₃ CHFCH ₃ (boiling point: −1 ° C.), CF ₃ CH ₂ CH ₃ (boiling point: −13) _{℃), CH 3 CF 2 CH} 3 ( boiling _{: -1 ℃), CH 3 CHFCH} 3 ( boiling _{point: -9 ℃), CF 3 CF} 2 CF 2 CH 3 ( boiling point: 15 ° C.) and the like. As perfluoro compounds, CF ₄ (boiling point: −128 ° C.), C ₂ F ₆ (boiling point: −78 ° C.), C ₃ F ₈ (boiling point: −37 ° C.), C ₄ F ₁₀ (boiling point: −2 ° C.) ), C ₆ F ₆ (perfluorobenzene) (boiling point: 4 ° C.). Examples of the hydrocarbon include propane (boiling point: −42 ° C.) and butane (boiling point: −1 ° C.).

Examples of organic compounds having a boiling point higher than 20 ° C. that may be used in combination as the foaming agent include the following HFCs, perfluoro compounds, and hydrocarbons. As HFC, CHF ₂ CF ₂ CH ₂ F (boiling point: 25 ° C.), CH ₂ FCF ₂ CH ₂ F (boiling point: 36 ° C.), CHF ₂ CHFCH ₂ F (boiling point: 40 ° C.), CF ₃ CH ₂ CH ₂ F (boiling point: 29 ° C.), CF ₃ CH ₂ CH ₂ CF ₃ (boiling point: 25 ° C.), CF ₃ CHFCF ₂ CH ₃ (boiling point: 25 ° C.), CF ₃ CH ₂ CF ₂ CH ₃ (HFC-365mfc, boiling point) : 40 ° C.), CF ₃ CHFCHFCF ₃ (boiling point: 25 ° C.), CF ₃ CF ₂ CF ₂ CH ₂ F (boiling point: 28 ° C.), CF ₃ CHFCH ₂ CF ₃ (boiling point: 31 ° C.), CH ₃ CF ₂ CF ₂ CHF ₂ (boiling point: 32 ° C.), CF ₃ CF ₂ CHFCHF ₂ (boiling point: 32 ° C.), CF ₃ CF ₂ CH ₂ CHF ₂ (boiling point: 39 ° C.), CF ₃ CHFCHFCH ₃ ( Boiling point: 40 ° C., CF ₃ CH (CF ₃ ) CH ₃ (boiling point: 22 ° C.), CH ₃ CF (CF ₃ ) CHF ₂ (boiling point: 29 ° C.), CH ₃ CH (CF ₃ ) CH ₂ F (boiling point) : 32 ° C.), CH ₃ CH (CF ₃ ) CHF ₂ (boiling point: 41 ° C.), CH ₂ FCF (CF ₃ ) CH ₂ F (boiling point: 48 ° C.), CH ₃ CF (CHF ₂ ) CHF ₂ (boiling point: 49 ° C.). As the perfluoro _compound, C _{5 F 12} (boiling _{point: 30 ℃), C 6 F} 14 ( boiling _{point: 56 ℃), C 7 F} 16 ( boiling _{point: 82 ℃), C 5 F} 10 ( perfluoro-cyclopentane) (Boiling point: 21 ° C.), C ₆ F ₁₂ (perfluorocyclohexane) (boiling point: 51 ° C.). Examples of the hydrocarbon include pentane (boiling point: 35 ° C.), hexane (boiling point: 69 ° C.), cyclopentane (boiling point: 49 ° C.), and cyclohexane (boiling point: 80 ° C.).

  In the present invention, it is preferable to include HFC-245fa and / or HFC-134a as the foaming agent, and it is more preferable to include an HFC mixture composed of HFC-245fa and HFC-134a (hereinafter referred to as a specific HFC mixture). It is particularly preferable to include only a specific HFC mixture as a blowing agent other than water. That is, the proportion of the specific HFC mixture as a blowing agent other than water is preferably 50% by mass or more, more preferably 80% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass. The ratio of HFC-245fa in the specific HFC mixture is preferably 1 to 99% by mass, more preferably 1 to 80% by mass, further preferably 5 to 60% by mass, and particularly preferably 5 to 45% by mass.

  In this invention, 5-150 mass parts is preferable with respect to 100 mass parts of polyol compounds, and, as for the usage-amount of the organic compound used as a foaming agent, 20-60 mass parts is more preferable. Moreover, when using water together as a foaming agent by this invention, 0.1-5 mass parts is preferable with respect to 100 mass parts of polyol compounds, and 2-4 mass parts is more preferable. Moreover, although a foaming agent is normally mixed and used for a polyol compound, in order to reduce a froth void, you may add a part of foaming agent except water to an isocyanate compound.

(Foam stabilizer)
In this invention, it is preferable to use 0.1-5 mass parts of the following foam stabilizer (F) with respect to 100 mass parts of the whole polyol compound as a foam stabilizer. However, the foam stabilizer (F) is a silicone foam stabilizer in which a polyoxyalkylene chain is grafted to a polysiloxane chain, the chain length of the polysiloxane chain is 2000 to 3000, and the polyoxyalkylene chain The chain length is 1000 to 2000, the number of grafts is 1.5 to 2.5, the polyoxyalkylene chain end does not have a hydroxyl group, and the ratio of the polysiloxane chain to the total foam stabilizer is 30 to 30. It is a silicone foam stabilizer that is 50% by mass. The use of the specific foam stabilizer (F) is preferable because the foam is stabilized during the foaming process, and the generation of froth voids is efficiently suppressed.

  The specific foam stabilizer (F) has a polysiloxane chain and a polyoxyalkylene chain. Here, the polysiloxane chain means an organopolysiloxane chain having an organic group in the side chain, and examples thereof include a dimethylsiloxane chain. The polyoxyalkylene chain means a portion to which alkylene oxide is added. Examples of the addition of alkylene oxide include block addition in which a single alkylene oxide is added, random addition in which two or more alkylene oxides are randomly added, and these additions may be mixed. The foam stabilizer has a structure in which a polyoxyalkylene chain is grafted as a side chain to a main polysiloxane chain.

  The silicone content of the foam stabilizer (F) is 30 to 50% by mass. Here, the silicone content is the ratio of the polysiloxane chain in the foam stabilizer (F), and the remainder is the polyoxyalkylene chain. Examples of the alkylene oxide include ethylene oxide, propylene oxide, 1,2-epoxybutane, and 2,3-epoxybutane. Among these, only ethylene oxide or a combination of ethylene oxide and propylene oxide is preferable.

  The polyoxyalkylene chain has a chain length of 1000 to 2000. However, this chain length is a value corresponding to the molecular weight. For example, when the polyoxyalkylene chain is composed only of oxypropylene groups and the chain length is 1160, polyoxyalkylene with 20 propylene oxides (molecular weight 58) added. Means a chain. The polyoxyalkylene chain does not have a hydroxyl group at the end. That is, the terminal is preferably OR (where R is a monovalent organic group). Examples of the monovalent organic group include an alkyl group such as a methyl group, an ethyl group, and an isopropyl group; an aryl group such as a phenyl group; an acyl group such as an acetyl group. Among these, an organic group having 1 to 6 carbon atoms. Groups are preferred.

  In the present invention, two or more types of the specific foam stabilizer (F) may be used in combination, or a foam stabilizer other than the specific foam stabilizer may be used in combination. The amount of the specific foam stabilizer (F) used is preferably 0.1 to 5 parts by mass, more preferably 1 to 4 parts by mass, and particularly preferably 2 to 3 parts by mass with respect to 100 parts by mass of the polyol compound. .

(Isocyanate compound)
In the present invention, the isocyanate compound is not particularly limited, but aromatic, alicyclic and aliphatic polyisocyanates having two or more isocyanate groups; a mixture of two or more of the above polyisocyanates; Examples thereof include modified polyisocyanates obtained by modification. Specific examples include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymethylene polyphenyl isocyanate (common name: crude MDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HMDI), and the like. These polyisocyanates or their prepolymer-modified products, nurate-modified products, urea-modified products, carbodiimide-modified products, and the like. Of these, TDI, MDI, crude MDI, or modified products thereof are preferred.

(catalyst)
The catalyst used in the present invention is not particularly limited as long as it promotes the urethanization reaction. For example, triethylenediamine, bis (2-dimethylaminoethyl) ether, N, N, N ′, N′— Tertiary amines such as tetramethylhexamethylenediamine; carboxylic acid metal salts such as potassium acetate and potassium 2-ethylhexanoate; and organometallic compounds such as dibutyltin dilaurate.

(Other ingredients)
In the present invention, any compounding agent can be used in addition to the above-described polyol compound, isocyanate compound, foaming agent, foam stabilizer, and catalyst. Compounding agents include fillers such as calcium carbonate and barium sulfate; anti-aging agents such as antioxidants and UV absorbers; flame retardants, plasticizers, colorants, anti-fungal agents, foam breakers, dispersants, discoloration prevention Agents and the like.

(Foaming device)
The method for producing a rigid foam of the present invention can be effectively applied to any foaming apparatus that can use a gaseous foaming agent at room temperature. Any of a high pressure foaming apparatus, a low pressure foaming apparatus, and a simple type (low pressure) foaming apparatus can be used, and it is particularly suitable for a low pressure foaming apparatus and a simple type foaming apparatus. As the simple foaming device, a simple foaming device that operates only by pressure operation of the gas supplied from the gas cylinder is preferable.

  An outline of an example of the configuration of this simple foaming apparatus is shown in FIG. The simple foaming apparatus shown in FIG. 1 is an active hydrogen compound side cylinder 1 filled with an active hydrogen compound, an isocyanate compound side cylinder 2 filled with an isocyanate compound, and the like for discharging these raw materials from the cylinder. An inert gas cylinder 3 filled with an inert pressurized gas such as nitrogen gas, a solvent cylinder 4 filled with a cleaning solvent, a flow controller 5 for controlling the discharge amount of the raw material, and the raw material discharged from two tanks Has a static mixer 6 for uniformly mixing.

  This foaming device operates only by the pressure operation of a gas such as nitrogen supplied from an inert gas cylinder 3 and is discharged and mixed from two cylinders 1 and 2 filled with active hydrogen compounds and isocyanate compounds separately. It is something to be made. An example of such a simple foaming apparatus is a brand name Auto Floss (manufactured by Asahi Glass Co., Ltd.) This is because, compared with the low pressure foaming machine and the high pressure foaming machine which have been used conventionally, (1) the flowability is good and the injection amount can be easily reduced, and (2) the foaming pressure is low, which is large. No mold clamping equipment is required. (3) As a result, the capital investment can be suppressed.

  The method for producing a rigid foam of the present invention is suitable for the production of a heat insulating panel used for a vending machine, a refrigerator, a freezer, a freezer warehouse, a cold storage warehouse, a cold storage warehouse, a heat insulation vehicle, and the like. It is also suitable for manufacturing.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

The following polyols A1 to A4 and B1 to B5 were used in the formulations C1 to C7 shown in Table 1. However, the numerical value of Table 1 represents a mass part. Table 2 shows the foam stabilizer used.
Polyol A1: A polyoxyalkylene polyol obtained by reacting propylene oxide and ethylene oxide using glycerin as an initiator and having a hydroxyl value of 67 mgKOH / g and a ratio of oxyethylene groups of 7% by mass.
Polyol A2: A polyoxyalkylene polyol obtained by reacting propylene oxide and ethylene oxide using glycerin as an initiator and having a hydroxyl value of 67 mgKOH / g and an oxyethylene group ratio of 13% by mass.
Polyol A3: A polyoxyalkylene polyol obtained by reacting propylene oxide and ethylene oxide using glycerin as an initiator and having a hydroxyl value of 67 mgKOH / g and a proportion of oxyethylene groups of 20% by mass.
Polyol A4: A polyoxyalkylene polyol obtained by reacting propylene oxide and ethylene oxide using glycerin as an initiator and having a hydroxyl value of 42 mgKOH / g and a proportion of oxyethylene groups of 20% by mass.
Polyol B1: A polyoxyalkylene polyol having a hydroxyl value of 170 mgKOH / g, obtained by reacting propylene oxide with glycerol as an initiator.
Polyol B2: A polyoxyalkylene polyol having a hydroxyl value of 67 mgKOH / g, obtained by reacting propylene oxide with glycerol as an initiator.
Polyol B3: A polyoxyalkylene polyol having a hydroxyl value of 450 mgKOH / g, obtained by reacting propylene oxide with a mixed initiator of sucrose / glycerin.
Polyol B4: A polyoxyalkylene polyol having a hydroxyl value of 420 mgKOH / g, obtained by reacting propylene oxide with glycerol as an initiator.
Polyol B5: A polyoxyalkylene polyol obtained by reacting propylene oxide and ethylene oxide with a mixed initiator of sucrose / ethanolamine and having a hydroxyl value of 350 mgKOH / g and a ratio of oxyethylene groups of 10% by mass.

The following foam materials were used for the evaluation. In the vat, 100 parts by mass of a polyol mixture having a composition selected from C1 to C7, 2 parts by mass of water, 3.5 parts by mass of the silicone foam stabilizer shown in Table 2, and N, N-dimethylcyclohexylamine as a catalyst. A necessary amount such that the gel time was 135 seconds was added, and these were mixed and stirred well with a stirrer to obtain a polyol system liquid. This polyol system liquid was transferred to a predetermined cylinder of a foaming apparatus, weighed and filled. The following foaming agent is added so that the core density of the foam obtained at the time of free foaming (for example, foaming in an open box) is 28 ± 2 kg / m3. did. That is, although the amount differs depending on the foaming agent, about 30 to about 40 parts by mass of a foaming agent was added to 100 parts by mass of the polyol mixture. However, high-pressure injection equipment was used for the addition of HFC-134a. Crude MDI (manufactured by Nippon Polyurethane Industry Co., Ltd., MR-200) was used as the isocyanate compound, and was similarly weighed and filled into a cylinder.
Foaming agent H1: HFC-245fa / 134a = 40/60 (mass ratio) mixed foaming agent H2: HFC-245fa
Blowing agent H3: HFC-134a.

  Evaluation of foams and the like was carried out by the following method. The polyol system liquid and the isocyanate compound were foamed by adjusting the mixing ratio so that the isocyanate index was 110. Using a predetermined foaming apparatus, the raw material was poured into a 600 mm × 900 mm × 50 mm aluminum mold and foamed at room temperature. About the generation | occurrence | production degree of a void, the external appearance of the sample (foam) obtained by taking out from a metal mold | die was determined visually. About dimensional stability and thermal conductivity, the sample piece of the predetermined magnitude | size was cut out from the sample, and the below-mentioned measurement was performed. Moreover, about evaluation of compatibility (mixability), the pressure-resistant transparent glass container was filled with the foaming agent and the polyol system liquid, and the external appearance was determined visually. A high-pressure injection facility was used for filling the foaming agent.

  The combination of a polyol mixture and a foam stabilizer, and the result at the time of producing a foam are shown in Tables 3 and 4 in Examples 1 to 24. Examples 1 to 12 are examples using a high-pressure foaming apparatus as the foaming apparatus, and Examples 13 to 24 are examples using a simple foaming apparatus as the foaming apparatus. Examples 1 to 9 and Examples 13 to 21 are examples, and Examples 10 to 12 and Examples 22 to 24 are comparative examples. The judgment criteria for the compatibility evaluation were as follows: ○: transparent and no problem in use without separation, Δ: cloudy but no problem in use without separation. Judgment criteria for evaluation of the degree of occurrence of voids were: ◎: Almost no voids can be used, ◯: There are some voids but no problem in use, ×: Many voids are problematic in use. The dimensional stability was expressed by the rate of change (unit:%) with respect to the original thickness after the specimen was stored for 24 hours in an atmosphere of 70 ° C. and 95% relative humidity. However, the size of the sample piece was 30 mm × 30 mm × 30 mm. The thermal conductivity (unit: mW / m · K) was measured using an auto lambda HC-047 type (manufactured by Eiko Seiki Co., Ltd.). However, the size of the sample piece was 200 mm × 200 mm × 25 mm.

(High pressure foaming device)
28 kg of the polyol system liquid was transferred to a 50 kg cylinder for polyol components, weighed and filled. Molding of rigid foam using high pressure foaming device PU-50 (manufactured by PEC) under conditions of liquid temperature 25 ° C. (both 2 liquids), reaction mixture discharge rate 20 kg / min, discharge pressure 120 kg / cm ² (both 2 liquids) Went.

(Simple foaming device)
7 kg of the polyol system solution was transferred to a 10 kg cylinder for the polyol component, weighed and filled. After filling, the two liquid cylinders are placed in a heating chamber adjusted to 28 ° C. ± 2 ° C., respectively, and the liquid temperature is adjusted to 28-30 ° C., and a simple foaming device (manufactured by Asahi Glass Co., Ltd.) is used. Used to produce a rigid foam.

  As is apparent from the results of the above test, those using the specific polyol (A) of the present invention at the time of producing the rigid foam are excellent in compatibility, and are excellent in the appearance, dimensional stability and thermal conductivity of the obtained foam. I understood it. In particular, those using a specific foam stabilizer (F) had a very good appearance. On the other hand, when the specific polyol (A) was not used, many voids were generated and the appearance was poor.

It is the schematic of a structure of an example of the simple foaming apparatus used for this invention.

Explanation of symbols

1: active hydrogen compound side cylinder 2: isocyanate compound side cylinder 3: inert gas cylinder 4: solvent cylinder 5: flow controller 6: static mixer

Claims (5)

In a method for producing a rigid polyurethane foam by reacting a polyol compound and an isocyanate compound in the presence of a foaming agent, a foam stabilizer and a catalyst,
An organic compound having a boiling point of 20 ° C. or lower is used as at least a part of the foaming agent,
The manufacturing method of the rigid polyurethane foam characterized by using the polyol mixture which contains 0.5-30 mass% of following polyols (A) as a polyol compound.
However, the polyol (A) has a hydroxyl value of 40 mgKOH / g or more and 70 mgKOH / g or less, a hydroxyl number of 2.8 to 5.2, and an oxyethylene group of 5 to the whole polyol (A). It is a polyoxyalkylene polyol containing -40% by mass.   2. The organic compound having a boiling point of 20 ° C. or less used as the blowing agent includes 1,1,1,3,3-pentafluoropropane and / or 1,1,1,2-tetrafluoroethane. Manufacturing method for rigid polyurethane foam.   The organic compound having a boiling point of 20 ° C. or less used as the blowing agent includes a fluorinated hydrocarbon mixture composed of 1,1,1,3,3-pentafluoropropane and 1,1,1,2-tetrafluoroethane. The method for producing a rigid polyurethane foam according to claim 2, wherein the proportion of 1,1,1,3,3-pentafluoropropane in the fluorinated hydrocarbon mixture is 1 to 99% by mass.   The manufacturing method of the rigid polyurethane foam of Claim 1, 2, or 3 using 0.1-5 mass parts of the following foam stabilizer (F) as said foam stabilizer with respect to 100 mass parts of the whole polyol compound. However, the foam stabilizer (F) is a silicone foam stabilizer in which a polyoxyalkylene chain is grafted to a polysiloxane chain, the chain length of the polysiloxane chain is 2000 to 3000, and the polyoxyalkylene chain The chain length is 1000 to 2000, the number of grafts is 1.5 to 2.5, the polyoxyalkylene chain end does not have a hydroxyl group, and the ratio of the polysiloxane chain to the total foam stabilizer is 30 to 30. It is a silicone foam stabilizer that is 50% by mass.   The manufacturing method of the rigid polyurethane foam of Claims 1-4 using the simple-type foaming apparatus which operate | moves only as pressure operation of the gas supplied from a gas cylinder as a foaming apparatus.

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