JP7601593B2 - Composition for forming polyurethane foam, polyurethane foam and heat insulating material - Google Patents

Description

The present invention relates to a composition for forming polyurethane foam, a polyurethane foam formed from the composition, and a heat insulating material made from the foam, and more specifically, to a composition for forming a polyurethane foam having excellent surface quality, particularly smoothness, of a molded product.

Among resin-based foams, polyurethane foam, especially rigid polyurethane foam, has excellent insulating properties and is therefore widely used as a foam-based insulating material. Polyurethane foam is usually produced by mixing polyol and polyisocyanate together with catalysts, blowing agents, foam stabilizers, etc., which are appropriately blended as necessary, and foaming the mixture.

Conventionally, hydrofluorocarbon (HFC) blowing agents such as HFC-134a, HFC-245fa, and HFC-365mfc have been used as blowing agents for rigid polyurethane foams. However, although these hydrofluorocarbon blowing agents are recognized as alternatives to fluorocarbons that cause little or no ozone layer depletion, they have a high global warming potential due to their chemical stability, and there are concerns that the use of HFC blowing agents will lead to global warming, so a gradual reduction in their use is being promoted under the Montreal Protocol (Kigali Amendment).

In recent years, halogenated hydroolefin blowing agents called hydrofluoroolefins (HFOs), which are chemically unstable and therefore have a lower global warming potential, have begun to be used in place of these HFC blowing agents.

JP 2016-74886 A (Patent Document 1) describes an invention relating to a polyol composition for rigid polyurethane foams that contains 1-chloro-3,3,3-trifluoropropene (HFO-1233zd) as an essential blowing agent component. The invention described in Patent Document 1 aims to provide a polyol composition for rigid polyurethane foams that has good stock solution storage stability even when HFO-1233zd is used as the blowing agent component, and that can suppress deterioration of the physical properties of the rigid polyurethane foam, and is characterized by containing ethyl diglycol acetate as a compatibilizer for HFO-1233zd.

In addition, although not characterized by the use of HFO as a blowing agent, JP-T-2019-533754 (Patent Document 2) aims to provide a polyol composition that is stable under all conditions, specifically a polyol composition that is stable for at least 24 hours, and in some cases for more than 6 months, in order to solve the problem that polyol compositions used as raw materials for polyurethane foams tend to phase separate over time. The polyol composition described in Patent Document 2 is characterized by containing, together with two or more polyols, an ethoxylated alcohol represented by the formula: RO(CH ₂ CH ₂ O) _n H [wherein R is a C1-C31 linear or branched alkyl and n is an integer of 1 or more] and having a hydrophilic-lipophilic balance (HLB) value of about 3.7 or more.

JP 2016-74886 A Special table 2019-533754 publication

The inventors have investigated the use of hydrofluoroolefins (HFOs) as blowing agents for polyurethane foams and have found that when polyurethane foam is molded integrally with a facing material, the smoothness of the facing material of the resulting molded product is inferior to that of products using other blowing agents, resulting in a problem of reduced surface quality.

The object of the present invention is to provide a composition for forming a polyurethane foam that solves the above-mentioned problems of the conventional technology and has excellent surface quality, particularly smoothness, of the molded product. Another object of the present invention is to provide a polyurethane foam formed from the composition and a heat insulating material made of the foam.

The inventors have confirmed that the use of hydrofluoroolefins (HFOs) as blowing agents causes shrinkage in polyurethane foam, and believe that this shrinkage tends to reduce the smoothness of the facing material.

The process of forming polyurethane foam generally consists of (1) foaming caused by the reaction of polyisocyanate with water, and (2) the formation of urethane bonds caused by the reaction of polyisocyanate with polyol, and the reactions begin in this order. However, when HFO is used as the blowing agent, it is believed that the HFO volatilizes before bubbles are generated through the foaming process (1) above, causing the polyurethane foam to shrink.

Therefore, the present inventors have conducted extensive research to achieve the above object, and have discovered that a polyurethane foam having excellent surface smoothness can be formed by using a compound represented by formula 1: RO(CH ₂ CH ₂ O) _n R [wherein R is a C1-C3 linear or branched alkyl, and n is an integer of 1 or more] in a polyurethane foam-forming composition containing HFO as a blowing agent, thereby completing the present invention.

That is, the composition of the present invention is a composition for forming a polyurethane foam, which contains a hydrofluoroolefin as a blowing agent and 0.2 to 6 parts by mass of at least one compound represented by the following formula 1 per 100 parts by mass of the composition:
RO _{( CH2CH2O} ) _nR (Formula 1)
[In the formula, R is a C1-C3 linear or branched alkyl, and n is an integer of 1 or more.]

In a preferred embodiment of the composition of the present invention, the composition contains 25 parts by mass or more of polyether polyol per 100 parts by mass of the composition.

In another preferred embodiment of the composition of the present invention, the isocyanate index is 150 or less.

In another preferred embodiment of the composition of the present invention, the viscosity of the polyol contained in the composition is 500 mPas (25°C) or more.

The polyurethane foam of the present invention is a polyurethane foam obtained by foaming the above composition.

A suitable example of the polyurethane foam of the present invention is a polyurethane foam with a facing material.

The insulating material of the present invention is also made of the polyurethane foam.

The composition of the present invention can provide a composition for forming a polyurethane foam having excellent surface quality, particularly smoothness, of a molded product. Furthermore, the polyurethane foam of the present invention can provide a polyurethane foam formed from such a composition, and the insulating material of the present invention can provide an insulating material made of such a polyurethane foam.

The present invention is described in detail below.

One aspect of the present invention is a composition for forming polyurethane foam. Such a composition contains a polyol, a polyisocyanate, and a blowing agent, and by mixing these, a reaction between the polyol and the polyisocyanate proceeds, making it possible to form a polyurethane foam. In this specification, the composition for forming polyurethane foam of the present invention is also referred to as the composition of the present invention.

The polyol is a compound having multiple hydroxyl groups, and is preferably a polymer polyol. Specific examples of polyols include polyether polyols, polyester polyols, polycarbonate polyols, polylactone polyols, polybutadiene polyols, polymer polyols, and Mannich polyols.

In the composition of the present invention, the amount of polyol is appropriately adjusted according to the amount of polyisocyanate, but is, for example, 25 to 40 parts by mass per 100 parts by mass of the composition. The polyol may be used alone or in combination of two or more kinds.

A representative example of polyether polyol is polyoxyalkylene polyol, which can be produced by subjecting a starting material such as a compound having two or more hydroxyl groups, primary amino groups, secondary amino groups, or other active hydrogen-containing groups to a ring-opening addition reaction with alkylene oxide.

Starting materials for polyoxyalkylene polyols include polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol, diglycerin, mannose, sucrose, fructose, dextrose, and sorbitol; alkanolamines such as ethanolamine, diethanolamine, triethanolamine, and methyldiethanolamine; polyhydric amines such as ethylenediamine, tolylenediamine, diethyltoluenediamine, 1,3-propanediamine, 1,6-hexanediamine, isophoronediamine, diethylenetriamine, and triethylenepentamine; polyhydric phenols such as bisphenol A, bisphenol F, resorcinol, and hydroquinone; and modified products thereof. These starting materials may be used alone or in combination of two or more.

When producing polyoxyalkylene polyols, alkylene oxides that undergo ring-opening addition reaction include ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, styrene oxide, etc., and these alkylene oxides may be used alone or in combination of two or more.

Examples of polymer polyols include those in which polymer particles such as polyacrylonitrile particles or polystyrene particles are dispersed in a polyoxyalkylene polyol. Since polymer polyols contain a polyoxyalkylene polyol, they are a type of polyether polyol.

Mannich polyols can be produced by condensation reactions of phenols, aldehydes, alkanolamines, etc., followed by ring-opening addition reactions of alkylene oxides such as ethylene oxide and propylene oxide, if necessary. Mannich polyols are a type of polyether polyol because they have multiple ether bonds in the molecule.

Examples of suitable polyether polyols include polyoxyalkylene polyols such as (di)ethylene glycol-based polyether polyols obtained by addition reaction of ethylene oxide and/or propylene oxide, (di)propylene glycol-based polyether polyols, (di)glycerin-based polyether polyols, trimethylolpropane-based polyether polyols, pentaerythritol-based polyether polyols, sucrose-based polyether polyols, dextrose-based polyether polyols, sorbitol-based polyether polyols, mono(di, tri)ethanolamine-based polyether polyols, ethylenediamine-based polyether polyols, tolylenediamine-based polyether polyols, and bisphenol A-based polyether polyols, polymer polyols in which polymer particles are dispersed in polyoxyalkylene-based polyols, and Mannich polyols.

Polyester polyols can be produced by adjusting the production conditions of polyesters. For example, polyester polyols having at least hydroxyl groups at both ends of the main chain can be used. More specifically, polyester polyols include linear polyester polyols and slightly branched polyester polyols. Polyester polyols can be prepared by known methods using aliphatic, alicyclic or aromatic dicarboxylic acids, diols, and optionally polyvalent carboxylic acids and/or trifunctional or higher polyols.

Polylactone polyols are homopolymers or copolymers of lactones, and examples of such polylactones include polylactones having hydroxyl groups at least at both ends of the main chain. Specifically, they can be produced by subjecting lactones such as ε-caprolactone, β-butyrolactone, γ-butyrolactone, γ-valerolactone, and δ-valerolactone to a ring-opening addition reaction using compounds having two or more active hydrogen-containing groups as described above for the polyoxyalkylene polyols as starting materials. Polylactone polyols are a type of polyester polyol because they have multiple ester bonds in the molecule.

Polycarbonate polyols can be produced by adjusting the production conditions of polycarbonate, and examples of such polycarbonate polyols include polycarbonates having hydroxyl groups at least at both ends of the main chain. Also, examples of such polybutadiene polyols include polybutadienes having hydroxyl groups at least at both ends of the main chain.

The composition of the present invention preferably contains a polyether polyol as the polyol. The amount of polyether polyol is preferably 25 parts by mass or more, more preferably 25 to 40 parts by mass, and even more preferably 30 to 35 parts by mass, relative to 100 parts by mass of the composition of the present invention. When a polyether polyol, particularly a polyether polyol having a high hydroxyl value that exhibits relatively hydrophilic properties, is used in the amount specified above, the effect of the compound represented by formula 1 described below is easily exhibited.

In the composition of the present invention, the hydroxyl value of the polyol is preferably 200 to 500 mg KOH/g, and more preferably 300 to 400 mg KOH/g.

In this specification, the hydroxyl value is the number of milligrams of sodium hydroxide required to neutralize the free hydroxyl groups in 1 g of sample after they have been completely acetylated with a carboxylic anhydride (e.g., phthalic anhydride or acetic anhydride) (see JIS K 1557 2007).

In the composition of the present invention, the molecular weight of the polyol is preferably 400 to 800 g/mol, more preferably 500 to 600 g/mol.

In this specification, the molecular weight of a polyol is the number average molecular weight calculated using polystyrene standards and measured by gel permeation chromatography.

In the composition of the present invention, the functionality (fn) of the polyol is preferably 2.5 to 4.5, and more preferably 3.0 to 4.0.

In this specification, the number of functional groups (fn) per molecule of polyol is calculated from the hydroxyl value (OHV) and number average molecular weight (Mn) of the polyol by the following formula.
fn=Mn (g/mol)×OHV (mgKOH/g)/56100

The viscosity of the polyol contained in the composition of the present invention is preferably 500 mPas (25°C) or more, more preferably 600 to 3000 mPas (25°C), and even more preferably 700 to 2000 mPas (25°C). If the viscosity of the polyol contained in the composition of the present invention is less than 500 mPas (25°C), the composition may splash during application, which may cause defects in the foam. The viscosity of the polyol can be easily increased, for example, by using an aromatic amine-based polyether polyol.

In this specification, viscosity is measured in accordance with JIS K 7117-1:1999 using a Brookfield rotational viscometer type B.

When the composition of the present invention contains a plurality of polyols, the viscosity of the polyol is the viscosity of the entire polyol, and can be calculated, for example, from the viscosity and mass fraction of each polyol as follows.
[Polyol Viscosity]
When the composition of the present invention contains n types of polyols, the viscosity of each polyol is ^V1 , ^V2 , ..., ^Vn , and the mass fraction of each polyol in the total polyols is ^W1 , ^W2 , ..., ^Wn , and the viscosity can be calculated by the following formula.
Viscosity of polyol=exp( ^W1 ×ln( ^V1 )+ ^W2 ×ln( ^V2 )+...+ ^Wn ×ln( ^Vn ))

Polyisocyanates are compounds having multiple isocyanate groups, and examples of such polyisocyanates include aliphatic, alicyclic, aromatic, or araliphatic polyisocyanates, as well as modified products of these polyisocyanates. Examples of modified polyisocyanates include polyisocyanates having structures such as uretdione, isocyanurate, urethane, urea, allophanate, biuret, carbodiimide, iminooxadiazinedione, oxadiazinetrione, and oxazolidone. In addition, as the polyisocyanate, an isocyanate group-containing prepolymer obtained by reacting a polyol with a polyisocyanate may be used. The polyisocyanates may be used alone or in combination of two or more kinds.

Among polyisocyanates, examples of aromatic polyisocyanates include phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, dimethyldiphenylmethane diisocyanate, triphenylmethane triisocyanate, naphthalene diisocyanate, polymethylene polyphenyl polyisocyanate, etc. Examples of alicyclic polyisocyanates include cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, dimethyldicyclohexylmethane diisocyanate, etc. Examples of aliphatic polyisocyanates include methylene diisocyanate, ethylene diisocyanate, propylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, etc.

The polyisocyanate preferably has an isocyanate group content of 20 to 40% by mass, and more preferably 25 to 35% by mass. In this specification, the isocyanate group content is determined in accordance with JIS K 1603-1:2007.

In the composition of the present invention, the amount of polyisocyanate can be indicated, for example, by the isocyanate index. In the composition of the present invention, from the viewpoint of the heat insulating properties of the polyurethane foam, it is preferable that the isocyanate index is set low. Specifically, the isocyanate index is preferably 150 or less, more preferably 90 to 150, even more preferably 90 to 130, and particularly preferably 100 to 125.

In this specification, the isocyanate index is the ratio of the isocyanate groups of the polyisocyanate to the total active hydrogen that reacts with the isocyanate groups of the polyol, blowing agent, etc., multiplied by 100.

Foaming agents are generally classified into physical and chemical foaming agents. The foaming agents may be used alone or in combination of two or more. A physical foaming agent may be used in combination with a chemical foaming agent. The amount of the foaming agent is preferably 0.5 to 15 parts by mass, more preferably 3 to 12 parts by mass, per 100 parts by mass of the composition of the present invention.

Specific examples of physical blowing agents include fluorocarbons such as hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), hydrocarbons such as heptane, hexane, pentane, and cyclopentane, and carbon dioxide. On the other hand, examples of chemical blowing agents include water and carboxylic acids such as formic acid and acetic acid.

The composition of the present invention contains hydrofluoroolefin as a blowing agent. Hydrofluoroolefin (HFO) is a blowing agent that is preferably used as a physical blowing agent that does not fall under the category of fluorocarbons. HFO is an olefin compound containing fluorine atoms, and also includes those that further contain halogen atoms other than fluorine (e.g., chlorine atoms). HFOs that further contain chlorine atoms are also called hydrochlorofluoroolefins (HCFOs). The composition of the present invention preferably contains hydrochlorofluoroolefin. Note that HFOs and HCFOs may be distinguished from each other, but in this specification, HFOs include HCFOs as described above.

The hydrofluoroolefin preferably has 2 to 5 carbon atoms and 3 to 7 fluorine atoms. The molecular weight of the HFO is preferably 100 to 200 g/mol. Specific examples of HFO include 1,2,3,3,3-pentafluoropropene, 1,3,3,3-tetrafluoropropene, 2,3,3,3-tetrafluoropropene, 1,2,3,3-tetrafluoropropene, 3,3,3-trifluoropropene, 1,1,1,4,4,4-hexafluorobutene, 1-chloro-3,3,3-trifluoropropene, 2-chloro-3,3,3-trifluoropropene, 3,3-dichloro-3-fluoropropene, 2-chloro-1,1,1,4,4,4-hexafluorobutene, and 2-chloro-1,1,1,3,4,4,4-heptafluorobutene. The HFO may be either a cis or trans isomer. These HFOs may be used alone or in combination of two or more.

The amount of hydrofluoroolefin is, for example, 0.5 to 15 parts by mass, and preferably 3 to 12 parts by mass, per 100 parts by mass of the composition of the present invention.

From the viewpoint of improving the appearance and strength of the foam, the composition of the present invention preferably contains water as a blowing agent. The amount of water is, for example, 0.2 to 10 parts by mass, and preferably 0.5 to 3 parts by mass, per 100 parts by mass of the composition of the present invention.

The composition of the present invention comprises at least one compound represented by the following formula 1:
RO _{( CH2CH2O} ) _nR (Formula 1)
[In the formula, R is a C1-C3 linear or branched alkyl, and n is an integer of 1 or more.]

The composition of the present invention preferably contains a polyether polyol. Due to its structure, polyether polyol has hydrophilic properties that make it easily soluble in water. Therefore, as the reaction between the polyol and the polyisocyanate progresses, a hydrophobic structure is formed, but hydrophilicity is maintained to a certain extent.

On the other hand, hydrofluoroolefins (HFOs) used as foaming agents are hydrophobic and move to the hydrophobic side during the reaction between polyol and polyisocyanate. As the heat of reaction gradually increases, the HFO also volatilizes, but if there is a large amount of hydrophilic structure such as polyether polyol, the HFO is difficult to dissolve, so the HFO volatilizes all at once in the early stages of the reaction. When the HFO volatilizes all at once, the resin becomes soft in certain places due to the high solubility of the HFO in the resin, and it is thought that this softness leads to contraction of the foam and loss of smoothness on the surface of the facing material.

The compound represented by the above formula 1 is relatively hydrophobic, so it is possible to control the dissolution of HFOs into a resin obtained from a raw material containing a hydrophilic polyether polyol, and to solve the problem of the resin becoming soft at certain locations.

In the above formula 1, R is a C1-C3 linear or branched alkyl, specific examples of which include methyl, ethyl, and propyl (normal propyl, isopropyl). The two Rs in formula 1 may be the same or different.

In the above formula 1, n is an integer of 1 or more, preferably an integer of 1 to 12, and more preferably an integer of 5 to 10.

The compound represented by the above formula 1 is preferably 0.2 to 6 parts by mass, and more preferably 0.5 to 3 parts by mass, per 100 parts by mass of the composition of the present invention. If the amount of the compound represented by the above formula 1 is too large, the compound tends to come out to the surface, and the flammability is reduced, making the composition more likely to burn.

The composition of the present invention preferably contains a catalyst. Examples of the catalyst include a catalyst that promotes the reaction between water and polyisocyanate (foaming catalyst), a catalyst that promotes the reaction between polyol and polyisocyanate (resinification catalyst), and a catalyst that promotes the trimerization reaction of polyisocyanate (i.e., the formation of an isocyanurate ring) (trimerization catalyst).

Examples of foaming catalysts include dimorpholine-2,2-diethyl ether, N,N,N',N'',N''-pentamethyldiethylenetriamine, bis(dimethylaminoethyl)ether, 2-(2-dimethylaminoethoxy)ethanol, and N,N,N'-trimethyl-N'-hydroxyethylbisaminoethylether.

Examples of resinification catalysts include triethylenediamine, N,N-dimethylcyclohexylamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'',N''',N'''-hexamethyltriethylenetetramine, N-dimethylaminoethyl-N'-methylpiperazine, N,N,N',N'-tetramethylhexamethylenediamine, 1,2-dimethylimidazole, 1-isobutyl-2-methylimidazole, N,N-dimethylaminopropylamine, bis(dimethylaminopropyl)amine, etc. Examples of the catalyst include amine catalysts such as N,N-dimethylaminoethanol, N,N,N'-trimethylaminoethylethanolamine, N-(3-dimethylaminopropyl)-N,N-diisopropanolamine, N-(2-hydroxyethyl)-N'-methylpiperazine, N,N-dimethylaminohexanol, and 5-dimethylamino-3-methyl-1-pentanol, as well as metal catalysts such as stannous octoate, dibutyl stannous dilaurate, lead octoate, bismuth carboxylate, and zirconium complexes. As these amine catalysts and alkanolamine catalysts, amine carbonates synthesized by adding carbonic acid and amine carboxylates synthesized by adding carboxylic acids such as formic acid and acetic acid may be used.

Examples of trimerization catalysts include aromatic compounds such as 2,4,6-tris(dialkylaminoalkyl)hexahydro-S-triazine, 1,3,5-tris(N,N-dimethylaminopropyl)hexahydro-S-triazine, 2,4,6-tris(dimethylaminomethyl)phenol, and 2,4-bis(dimethylaminomethyl)phenol; alkali metal salts of carboxylic acids such as potassium acetate, potassium 2-ethylhexanoate, and potassium octylate; quaternary ammonium salts of carboxylic acids; and other onium salts.

The amount of catalyst is, for example, 0.1 to 5 parts by mass, and preferably 0.3 to 1.5 parts by mass, per 100 parts by mass of the composition of the present invention. The catalyst may be used alone or in combination of two or more kinds.

The composition of the present invention may contain a foam stabilizer. The foam stabilizer is preferably a surfactant. The surfactant may be an ionic surfactant such as anionic, cationic, or amphoteric surfactant, or a nonionic surfactant, but a nonionic surfactant is preferable. Specific examples of the surfactant include silicone surfactants and fluorine surfactants. The amount of the foam stabilizer is preferably 1 to 5 parts by mass per 100 parts by mass of the composition of the present invention. The foam stabilizer may be used alone or in combination of two or more kinds.

The composition of the present invention may contain a flame retardant. The flame retardant is preferably a phosphorus-based flame retardant. Specific examples include tricresyl phosphate (TCP), triethyl phosphate (TEP), tris(β-chloroethyl) phosphate (TCEP), tris(β-chloropropyl) phosphate (TCPP), etc. Solid (powder) flame retardants such as ammonium polyphosphate and red phosphorus may also be used as needed. The amount of the flame retardant is preferably 3 to 15 parts by mass per 100 parts by mass of the composition of the present invention. The flame retardant may be used alone or in combination of two or more kinds.

The composition of the present invention may contain other additives such as colorants, fillers, antioxidants, UV absorbers, heat stabilizers, light stabilizers, plasticizers, fungicides, antibacterial agents, crosslinking agents, solvents, viscosity reducers, pressure reducers, and separation inhibitors, as necessary. Commercially available products can be used for these components.

The composition of the present invention can be prepared by mixing various components appropriately selected as necessary. For example, the composition of the present invention can be prepared by mixing a polyol component containing a polyol and a polyisocyanate component containing a polyisocyanate.

The composition of the present invention is often composed of a stock solution consisting of a pair of a polyol component and a polyisocyanate component. The polyol component contains a polyol, and usually contains a foaming agent, a foam stabilizer, and a catalyst, and may contain a flame retardant or further additives. The polyisocyanate component is composed of a polyisocyanate, but may contain additives such as a foaming agent and a flame retardant. The foaming agent may be added when the polyol component and the polyisocyanate component are mixed.

Another aspect of the present invention is a polyurethane foam. The polyurethane foam of the present invention is produced by foaming the polyurethane foam-forming composition of the present invention described above. Since the composition of the present invention contains a polyol and a polyisocyanate, by mixing the two, a reaction proceeds and it is possible to form a polyurethane foam. The temperature during polyurethane foam formation is preferably 20 to 80°C.

The foaming method of polyurethane foam is not particularly limited, and known foaming means such as hand mixing foaming, simple foaming, injection method, froth injection method, spray method, etc. can be used. The molding method of polyurethane foam is also not particularly limited, and known molding means such as mold molding, slab molding, laminate molding, in-situ foam molding, etc. can be used.

The polyurethane foam of the present invention can be used for a variety of applications, including ships, vehicles, plants, thermally insulated equipment, architecture, civil engineering, furniture, and interior design, but is particularly suitable for use as an insulating material, specifically as an insulating component for thermally insulated equipment, such as refrigerated warehouses and freezer warehouses.

The polyurethane foam of the present invention is preferably a polyurethane foam with a facing material, and more preferably a polyurethane foam with a metal facing material. In this specification, a facing polyurethane foam is a plate-shaped composite material in which a facing material such as foil or plate is attached to one or both sides of the polyurethane foam, and can be used as a heat insulating material for various applications.

Suitable examples of adherends such as surface materials include metals and other inorganic materials, particularly aluminum and its alloys, stainless steel and its alloys, iron and its alloys, and copper and its alloys. If desired, the surface of the adherend to which the composition of the present invention is to be applied may be coated. Examples of coatings include organic polymer coating agents such as polyester resins. The thickness of the adherend is preferably 0.2 to 0.6 mm.

The polyurethane foam of the present invention has a density of, for example, 5 to 80 kg/m ³ , preferably 25 to 70 kg/m ³ , and more preferably 40 to 65 kg/m ^3. In this specification, the density of the polyurethane foam is measured in accordance with JIS K 7222:2005.

When the measurement center temperature of the polyurethane foam of the present invention is 23°C, the thermal conductivity is preferably 0.0185 to 0.0280 W/m·K, and more preferably 0.0190 to 0.0260 W/m·K. In this specification, the thermal conductivity is measured in accordance with JIS A 1412-2:1999.

The polyurethane foam of the present invention can be suitably used in various applications requiring thermal insulation. In particular, the polyurethane foam of the present invention can be advantageously used as a building material or insulation material for various facilities such as apartment complexes, detached houses, schools and commercial buildings, as well as for refrigerated warehouses, bathtubs, factory piping, automobiles and railroad cars.

The polyurethane foam of the present invention can also be used for on-site application type insulation materials and condensation prevention materials by spraying, and for manufacturing building materials such as panels and boards on factory lines. Therefore, according to one embodiment of the present invention, the polyurethane foam is a spray-applied rigid polyurethane foam for building insulation as specified in JIS A 9526:2017.

Another aspect of the present invention is a heat insulating material. The heat insulating material of the present invention is a heat insulating material made of the polyurethane foam of the present invention described above. Examples of heat insulating materials include heat insulating components for heat insulating equipment, such as refrigerated warehouses and freezer warehouses. The heat insulating material of the present invention can also be used in various facilities such as apartment complexes, detached houses, schools, and commercial buildings, as well as freezer warehouses, bathtubs, factory piping, automobiles, and railroad cars.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

1. Overview Using a high-pressure foaming machine, a mixture of polyol and foaming agent (polyol component) and polyisocyanate are mixed in a specified ratio, and the mixture is discharged at a certain temperature and pressure into a mold with metal facing materials arranged above and below to obtain polyurethane foam. After a certain time, the depth near the injection point on the bottom surface is measured.

2. Equipment and devices High pressure foaming machine (HK-650P, manufactured by Hennecke)
Disposable chopsticks Stopwatch (with lap function)
Mold (aluminum, inner dimensions: length 2000 mm, width 900 mm, thickness 100 mm)

3. Materials 1) Polyol Polyol A: Polyether polyol [SBU Polyol 0517: manufactured by Sumika Covestro Urethane Co., Ltd.], number of functional groups: 4.1, hydroxyl value: 480 mg KOH/g, viscosity: 3400 mPa·s (25°C)
Polyol B: Polyether polyol [SBU Polyol 0487: manufactured by Sumika Covestro Urethane Co., Ltd.], number of functional groups: 4, hydroxyl value: 410 mg KOH/g, viscosity: 1500 mPa·s (25° C.)
Polyol C: aromatic amine-based polyether polyol [SBU Polyol Z450: manufactured by Sumika Covestro Urethane Co., Ltd.], number of functional groups: 4, hydroxyl value: 340 mg KOH/g, viscosity: 12,000 mPa·s (25° C.)
Polyol D: polyether polyol [SBU Polyol S429: manufactured by Sumika Covestro Urethane Co., Ltd.], number of functional groups: 3, hydroxyl value: 250 mg KOH/g, viscosity: 230 mPa·s (25° C.)
2) Polyisocyanate Polyisocyanate: Polymeric MDI [Sumidur 44V20 L: manufactured by Sumika Covestro Urethane Co., Ltd.], isocyanate group content: 31.5% by mass
3) Blowing agent Blowing agent A: Water Blowing agent B: HCFO-1233zd (molecular weight 130)
Foaming agent C: HFO-1224yd (molecular weight 148.5)
Foaming agent D: HFO-1336mzz (Z) (molecular weight 164)
4) Compatibilizer Compatibilizer A: diethylene glycol dimethyl ether, molecular weight 134, viscosity 1 mPa·s (25° C.)
Compatibilizer B: Tetraethylene glycol dimethyl ether, molecular weight 222, viscosity 4 mPa·s (25° C.)
Compatibilizer C: Polyoxyethylene-dimethyl ether [UNIOX MM-400: manufactured by NOF Corporation], average molecular weight 400, viscosity 100 mPa·s (25°C)
Compatibilizer D: diethylene glycol monobutyl ether, molecular weight 162, hydroxyl value 346, viscosity 6 mPa·s (25° C.)
Compatibilizer E: Ethyl diglycol acetate, molecular weight 176, viscosity 2.5 mPa·s (25° C.)
4) Other additives Catalyst A: Dimorpholine-2,2-diethyl ether Catalyst B: 1,2-dimethylimidazole 70% by mass + diethylene glycol 30% by mass
Foam stabilizer: silicone-based nonionic surfactant [TEGOSTAB B8460: manufactured by Evonik Japan Co., Ltd.]
Flame retardant: Tris(2-chloroisopropyl)phosphate 5) Surface material Aluminum surface material

3. Method <Preparation of polyol component>
1) Predetermined amounts of various polyols, catalysts, etc. are added to a nitrogen-purged mixing vessel and mixed.
2) Stir for at least 30 minutes and visually check that the mixture is thoroughly mixed.
3) Add the foaming agent to the mixture confirmed in 2) until the specified amount is reached, and mix thoroughly. After mixing, add the weighed amount of foaming agent and mix again.
The formulation (parts by mass) of the polyol component is shown in Tables 1 and 2.
<Production of Polyurethane Foam>
4) Using a high-pressure foaming machine HK-650P manufactured by Hennecke, the polyol component and the polyisocyanate component were adjusted to 19 to 23°C, and urethane injection molding was performed at a discharge pressure of 12 MPa. The mixing mass ratio of the polyol component and the polyisocyanate component is shown in Tables 1 and 2.
5) The foam-forming composition is poured into a single point in the center of a mold (inner dimensions: length 2000 mm, width 900 mm, thickness 100 mm) that has been preheated to 40°C and has aluminum panels arranged above and below.
6) Inject polyurethane foam in the length direction of the mold so that it does not completely fill the mold, cut both ends of the semicircle to obtain a rectangular sample, measure its weight and volume, and calculate the just density (kg/ ^m3 ). The density of the sample filled in the mold is called the just density.
7) The just weight of the mold (inner dimensions: length 2000 mm, width 900 mm, thickness 100 mm) is calculated from the just density, and 1.25 times that amount is poured into the mold to produce a polyurethane foam molded product.
8) 20 minutes after the foam-forming composition is injected, the polyurethane foam molding with the facing is removed from the mold.
9) After removing the polyurethane foam, place it under 0° C. conditions within 30 minutes, and then leave it for about 24 hours.
10) Place a straight ruler at a right angle on the underside of the surface material into which the urethane has been injected, and measure the maximum gap between the straight ruler and the surface material using a thickness gauge (Niigata Seiki Co., Ltd. 100ML) or a taper gauge (Niigata Seiki Co., Ltd. 270A). The results obtained are shown in Tables 1 and 2 as the "maximum recession of the injected underside."
11) For the lower surface of the panel, the image of the fluorescent light (straight tube type) reflected on the panel was visually observed and the smoothness was evaluated according to the following criteria. The evaluation results are shown in Tables 1 and 2.
(Evaluation Criteria)
: The surface was smooth and the image of the fluorescent light was visible as a straight line.
◯: The surface was smooth and the image of the fluorescent light was seen as a straight line, but there appeared to be slight minute irregularities.
×: The surface was not smooth, and wavy patterns of the fluorescent light image were visible.

<Method of measuring gel time>
In order to confirm the reactivity of the foam-forming composition, a certain amount of the composition was poured into a 2 L descup at a certain temperature and pressure without overflowing, and the time until the mixture started to form threads when touched with chopsticks after pouring was measured as the gel time (seconds). The measurement results are shown in Tables 1 and 2.

<Combustibility evaluation>
According to JIS A 9511:2017, a test piece having a thickness of 10 mm, a length of 200 mm, and a width of 25 mm was used and evaluated according to the following criteria. The measurement was performed by cutting a test piece of the above dimensions from the manufactured polyurethane foam, leaving it under the conditions of standard temperature condition class 3 (23°C ± 5°C) and standard humidity condition class 3 (50 ^{+ 20, -10} % R.H.) specified in JIS K 7100:1999, and one week after manufacture. The evaluation results are shown in Tables 1 and 2.
(Evaluation Criteria)
○ (Pass): The flame goes out within 3 seconds, there is no residual fuel, and the fire does not burn beyond the flammability limit indicator line.
× (Fail): Does not meet the above pass criteria.

From Tables 1 and 2, it can be seen that the polyurethane foams of the examples have superior surface quality of the molded products compared to Comparative Examples 1 and 5 to 8. It can also be seen that the polyurethane foams of Comparative Examples 2 to 4 have poor flammability because the amount of the compound represented by Formula 1 used was too large.

Claims (7)

A composition for forming a polyurethane foam, comprising a hydrofluoroolefin as a blowing agent and 0.2 to 6 parts by mass of at least one compound represented by the following formula 1, per 100 parts by mass of the composition:
RO _{( CH2CH2O} ) _nR (Formula 1)
[In the formula, R is a C1-C3 linear or branched alkyl, and n is an integer of 1 or more.] The composition according to claim 1, comprising 25 parts by mass or more of polyether polyol per 100 parts by mass of the composition. The composition according to claim 1 or 2, having an isocyanate index of 150 or less. The composition according to any one of claims 1 to 3, wherein the viscosity of the polyol contained in the composition is 500 mPas (25°C) or more. A polyurethane foam obtained by foaming the composition according to any one of claims 1 to 4. The polyurethane foam according to claim 5, which is a polyurethane foam with a facing. A heat insulating material made of the polyurethane foam according to claim 5 or 6.