JP7569415B2 - Method for manufacturing polyurethane foam filled structures - Google Patents

Description

The present invention relates to a method for manufacturing a polyurethane foam-filled structure in which an internal cavity is filled with polyurethane foam.

In the field of construction, various structures are used, such as resin molded bodies, metal frame materials, and molded bodies made of inorganic materials other than metals, such as cement. Each structure often has a cavity inside to reduce weight, and the inside of the cavity may be filled with insulating material, flame retardant material, etc. Polyurethane foam is known to be used as an insulating material and flame retardant material.

As shown in Patent Document 1, for example, when a panel is filled with polyurethane foam, it is known that a polyol liquid agent and a polyisocyanate liquid agent are mixed and then injected through a single injection hole provided on the side of the panel. The injected mixture of polyol liquid agent and polyisocyanate liquid agent (hereinafter also referred to as "polyurethane composition") reacts and foams in the cavity inside the panel, becoming polyurethane foam.

JP 2002-331604 A

Incidentally, cavities in various structural members used in buildings can be elongated or complex in shape. For example, when a panel is provided with openings corresponding to windows, the shape of the cavity becomes complex. In addition, in order to ensure strength, a partition wall may be provided inside the panel or plate-like member, or a rib having an elongated cavity inside may be provided.
However, if the cavity inside the structure has an elongated or complex shape, the polyurethane composition foams before it can reach the entire cavity, making it difficult to fill the entire cavity with the polyurethane foam.

In order to ensure that the polyurethane composition is distributed throughout the entire cavity, attempts have been made to extend a hose into the depths of long cavities or cavities with complex shapes, and inject the composition while pulling out the hose. However, this method requires that the reaction rate of the polyurethane composition be slowed down. In the case of a polyurethane composition with a slow reaction rate, the production time is long and a heating process using a heating device is required as a post-process, which is disadvantageous in terms of workability and practicality.

Therefore, the objective of the present invention is to provide a method for manufacturing a polyurethane foam-filled structure that can efficiently fill the entire cavity with polyurethane foam, even if the internal cavity is elongated or has a complex shape.

As a result of extensive investigation, the present inventors have found that the above problems can be solved by providing a plurality of injection holes communicating with cavities in a structure to be filled with a polyurethane foam and injecting a polyurethane composition through each injection hole using a spray gun, and have completed the present invention as described below. That is, the present invention provides the following (1) to (7).
(1) preparing a structure having a cavity therein and a plurality of injection holes communicating with the cavity;
A method for producing a polyurethane foam-filled structure, comprising: injecting a polyurethane composition into the cavity through the plurality of injection holes with a spray gun, causing the polyurethane composition to foam in the cavity, and filling the cavity with polyurethane foam.
(2) A method for producing a polyurethane foam filled structure as described in (1) above, in which a polyol liquid and a polyisocyanate liquid are mixed in a mixing and spraying device equipped with the spray gun, and the polyurethane composition obtained by mixing is discharged from the spray gun.
(3) A method for producing a polyurethane foam-filled structure according to (1) or (2) above, wherein the structure has an elongated cavity therein.
(4) The method for producing a polyurethane foam-filled structure according to any one of the above (1) to (3), further comprising sealing an injection hole after injecting the polyurethane composition.
(5) The method for producing a polyurethane foam-filled structure according to any one of (1) to (4) above, wherein the gel time of the polyurethane composition is 15 seconds or less.
(6) The method for producing a polyurethane foam-filled structure according to any one of (1) to (5) above, wherein the polyurethane composition contains a flame retardant.
(7) The method for producing a polyurethane foam-filled structure described in (6) above, wherein the flame retardant contains at least one selected from the group consisting of red phosphorus, phosphate esters, phosphate-containing flame retardants, bromine-containing flame retardants, boron-containing flame retardants, antimony-containing flame retardants, and metal hydroxides.

The present invention provides a method for manufacturing a polyurethane foam-filled structure that can efficiently fill the entire cavity with polyurethane foam, even if the internal cavity is elongated or has a complex shape.

FIG. 2 is a perspective view showing an example of a structure. FIG. 2 is a perspective view showing an example of a structure. FIG. 2 is a perspective view showing an example of a structure. FIG. 2 is a schematic diagram showing an example of a mixed injection device.

Hereinafter, the present invention will be described in detail with reference to embodiments.
The method for producing a polyurethane foam-filled structure of the present invention involves preparing a structure having an internal cavity and having a plurality of injection holes communicating with the cavity, injecting a polyurethane composition into the structure and allowing it to foam inside, thereby filling the cavity with the polyurethane foam.

[Structure]
In the present invention, the structure to be filled with polyurethane foam has a cavity inside. The structure is not particularly limited, but is preferably a building structure used in buildings. The cavity of the structure may have any shape, but is preferably a long cavity, more preferably a long and narrow cavity. It is also preferable that the cavity has a complex shape. In the present production method, even if a structure has a long and narrow cavity or a cavity of a complex shape, which has been difficult to fill with polyurethane foam in a short time, it can be filled with polyurethane foam in a short time with good workability.

A long cavity is one whose longitudinal length is, for example, twice or more the cross-sectional dimension. A long and narrow cavity is one whose longitudinal length is five times or more the cross-sectional dimension, preferably ten times or more, and more preferably thirty times or more. The cross-sectional dimension is the maximum length of the cross section of the cavity, for example, the major axis of an ellipse, and the length of the diagonal of a rectangle or square. When the size of the cross-sectional shape (i.e., the cross-sectional dimension) changes along the longitudinal direction, the maximum cross-sectional dimension of the varying part may be taken as the cross-sectional dimension.
Furthermore, a cavity having a complex shape refers to a cavity whose cross-sectional shape varies significantly along the longitudinal direction (e.g., the cross-sectional dimension varies by more than twice), or the cavity is branched or has a curved shape.

The injection holes formed in the structure may be two or more for each cavity formed inside the structure. That is, for example, when two or more cavities not communicating with each other are formed inside the structure, two or more injection holes may be connected to each cavity.
The position of the injection hole is not particularly limited, but when the cavity of the structure has a long or narrow shape, two or more injection holes are preferably provided along the longitudinal direction of the structure. In other words, the multiple injection holes are preferably arranged at different positions in the longitudinal direction. This makes it easier to fill the cavity with polyurethane foam even if the cavity is long or narrow.
It is also preferable that at least one injection hole is disposed closer to one end than the center in the longitudinal direction, and at least one other injection hole is disposed closer to the other end than the center in the longitudinal direction. This configuration makes it easier to fill a long or narrow cavity with polyurethane foam.
Furthermore, if the cavity has a complex shape, the position of the injection hole should be adjusted appropriately so that the polyurethane foam can fill the complex shape without leaving any gaps.

Specific examples of the structure include plate-like members and frame materials. Examples of the plate-like members include panels and flat decks. For example, the panel 10 shown in Fig. 1 is composed of main surface materials 11A and 11B that form the main surface of the panel and are spaced apart from each other to form a cavity 14 between them, and side surface materials 12A to 12D that form the side surfaces and surround the cavity 14. The panel 10 is a long object in which the length L of the main surface material 11 is, for example, twice or more the dimension of one side surface (for example, the diagonal length of the side surface materials 12A and 12C).
As shown in FIG. 1, in panel 10, injection holes 15A, 15B are provided in side members 12A, 12C, which are ends in the longitudinal direction, respectively, but the injection holes may be located in other positions.

The panel 20 shown in FIG. 2 is a panel having an opening 26, and as described above, in addition to the main panels 21A and 21B and the side panels 22A to 22D, an opening panel 23 for forming the opening 26 is provided. In the panel 20, for example, two openings 26 are provided, so that the cavity 24 is branched in three directions in the center near the side panels 22B and 22D and has a complex shape with bent corners. The injection holes need only be located in positions where the polyurethane foam can be filled throughout the cavity 24, and for example, injection holes 25A to 25E are provided in the center and each corner of the panel 21A, but the positions of the injection holes are not limited to these positions.

Fig. 3 shows an example in which the structure is a frame material. The frame material is a member that constitutes part or all of a frame body that surrounds an opening in a fixture such as a window or door. For example, the frame body is composed of a pair of side frame parts, an upper frame part, and a lower frame part, and the frame material may constitute at least a part of these frame parts.
The frame material 30 shown in FIG. 3 is a cylindrical member 31 having an elongated cavity 34 therein, and both ends of the frame material 30 may be closed by connecting to other frame materials, for example. The frame material 30 shown in FIG. 3 has a rectangular cross section, but may have other shapes such as a circle or a triangle. The frame material 30 is provided with a plurality of injection holes communicating with the cavity 34. For example, as shown in FIG. 3, a plurality of injection holes 35A to 35E may be arranged along the longitudinal direction. In the configuration of FIG. 3, the injection holes 35A to 35E are arranged at equal intervals, but may be spaced apart from equal intervals. Of course, the number of injection holes communicating with the cavity 34 may be any number of two or more, and for example, two injection holes may be provided only near both ends of the cylindrical member 31.

The structures shown in Figures 1 to 3 are examples of structures, and are not limited to these examples. Any structure may be used as long as it has a cavity inside. For example, a structure with a complex internal shape may be a structure in which a vacuum insulation panel is placed inside the panel described above (for example, panel 10 shown in Figure 1). The structure may also be, for example, a panel that constitutes the core material of metal siding.

In addition, a flat deck can be used as a plate-like member other than the above-mentioned panels. The flat deck can be obtained, for example, by roll forming a metal plate such as a steel plate. The flat deck is used, for example, as a formwork material for pouring concrete on the upper surface in a floor or roof structure.
The flat deck has a flat portion with a flat upper surface, and a plurality of reinforcing ribs are protruding from the lower surface of the flat portion. Each reinforcing rib is a protrusion with an internal cavity, is arranged extending along the longitudinal direction, and both ends in the longitudinal direction are crushed and closed. The cavity of each reinforcing rib is an elongated cavity, and both ends of the cavity are members whose cross-sectional shape changes significantly along the longitudinal direction when crushed, and have a complex shape. The cross-sectional shape of the reinforcing rib of the flat deck is not particularly limited as long as a cavity is formed inside, and may be a triangle, a rectangle, or other shape.
In a flat deck, the number of injection holes is not particularly limited as long as multiple injection holes are provided for each reinforcing rib. For example, the injection holes may be provided only near both ends of each reinforcing rib, or multiple injection holes may be arranged along the longitudinal direction of each reinforcing rib.

[Method of Injecting Polyurethane Composition]
A polyurethane composition is injected into each cavity inside the structure from a plurality of injection holes by a spray gun. The polyurethane composition contains a polyol component and a polyisocyanate component, and the polyol component and the polyisocyanate component react with each other in the cavity inside the structure to form a polyurethane resin. The polyurethane composition also contains a foaming agent, and is foamed by the foaming agent inside the cavity of the structure to become a polyurethane foam. The polyurethane foam has a large number of bubbles inside, has excellent heat insulation properties, and can be used as a heat insulation material. In addition, the polyurethane foam can also be used as a fire-resistant material by adding a flame retardant to enhance the flame retardancy and non-combustibility, as described later. Furthermore, the polyurethane foam may be used as a core material of the structure.

The method for injecting the polyurethane composition is not particularly limited, but a preferred method involves preparing in advance a polyol liquid agent containing a polyol component and a polyisocyanate liquid agent containing a polyisocyanate component, mixing them, and injecting the mixture (polyurethane composition) into the cavity using a spray gun.
More specifically, it is preferable to use a mixing/injecting device equipped with a spray gun, mix the polyol liquid agent and the polyisocyanate liquid agent in the mixing/injecting device, and then release the mixture from the spray gun to inject it into the cavity.

It is preferable to use a polyurethane composition that undergoes reaction and foaming even at room temperature (25° C.). By using such a polyurethane composition, a polyurethane foam can be formed by injecting the polyurethane composition and then leaving it at about room temperature without heating it using a heating means.
After the polyurethane composition is injected, the injection hole may be blocked by a blocking member that can be fitted into the injection hole, such as a resin cap or a screw.

Figure 4 shows one embodiment of the mixing and injection device. The mixing and injection device 60 shown in Figure 4 includes first and second containers 61 and 62 and a spray gun 68. The spray gun 68 is provided with a mixing section 63 in which the polyol liquid and the isocyanate liquid are mixed. The first container 61 contains the polyol liquid, and the second container 62 contains the isocyanate liquid. The first and second containers 61 and 62 are connected to pipes 64A and 64B, respectively, and the polyol liquid and the isocyanate liquid are transferred to the mixing section 63 via the pipes 64A and 64B.

The spray gun 68 is not particularly limited, but may be equipped with a handle that allows the spray gun 68 to be held by hand, a trigger, and the like. The spray gun 68 is provided with a valve or the like in the path through which the compressed air and polyurethane composition are introduced. The trigger operates the opening and closing of the valve, and when the trigger is pressed, the valve is opened, and the polyurethane composition obtained by mixing inside is discharged to the outside from the tip of the spray gun 68 by compressed air.

The first containers 61 and 62 are provided with on-off valves 65A and 65B, respectively, and the transfer can be interrupted by closing the on-off valves 65A and 65B. The polyol liquid and the isocyanate liquid are pressurized by compressed air from pressure means 67A and 67B such as air compressors and transferred to the mixing section 63.
The mixture (polyurethane composition) obtained in the mixing section 63 is discharged to the outside from the spray gun 68 together with compressed air supplied from the pressurizing means 67C. The pressurizing means 67C is not limited as long as it can supply compressed air to the spray gun 68, and an air compressor is an example of the pressurizing means 67C.

The polyol liquid and the isocyanate liquid are pressurized and transported to facilitate mixing in the mixing section 63, which may be provided with a mixing means such as a static mixer, if necessary. The mixture of the polyol liquid and the isocyanate liquid mixed in the mixing section 63 (polyurethane composition) is discharged to the outside from the spray gun 68 together with compressed air supplied from the pressurizing means 67C.

The mixing and injection device is not limited to the above-described configuration, and various modifications are possible. For example, the mixing unit 63 is provided inside the spray gun 68, but may be provided as a separate member from the spray gun 68.
In addition, the blowing agent is typically stored in the first container 61 in a state where it is mixed in advance with the polyol liquid agent as described later, but in the case where the blowing agent is an inorganic physical blowing agent such as carbon dioxide, it may be mixed with the polyurethane composition in the mixing section. More specifically, a carbon dioxide supplying device or the like may be provided, and carbon dioxide supplied from the carbon dioxide supplying device may be mixed with the polyol liquid agent and the polyisocyanate liquid agent in the mixing section.

In the present invention, as described above, it is necessary to inject the polyurethane composition into the cavity inside the structure from multiple injection holes, but since the polyurethane composition is injected into the cavity using a handheld spray gun, it is possible to fill the cavity with polyurethane foam with high workability. Furthermore, even if a polyurethane composition that is highly reactive and foams immediately after injection is used, providing multiple injection holes makes it easier to spread the polyurethane composition throughout the entire cavity. Therefore, even if the cavity is long and narrow or has a complex shape, it is possible to efficiently fill the entire cavity with polyurethane foam.

[Polyurethane composition]
The polyurethane composition used in the present invention contains a polyol component, a polyisocyanate component, and a foaming agent. The polyurethane composition becomes a polyurethane foam by reacting the polyol component with the polyisocyanate component and foaming the polyol component.

[Polyol component]
Examples of the polyol component include polylactone polyols, polycarbonate polyols, aromatic polyols, alicyclic polyols, aliphatic polyols, polyester polyols, polyether polyols, and polymer polyols.

Examples of the polylactone polyol include polypropiolactone glycol, polycaprolactone glycol, and polyvalerolactone glycol.
Examples of polycarbonate polyols include polyols obtained by dealcoholization reaction between hydroxyl group-containing compounds such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, octanediol, and nonanediol and diethylene carbonate, dipropylene carbonate, and the like.
Examples of aromatic polyols include bisphenol A, bisphenol F, phenol novolac, and cresol novolac.
Examples of the alicyclic polyol include cyclohexanediol, methylcyclohexanediol, isophoronediol, dicyclohexylmethanediol, and dimethyldicyclohexylmethanediol.
Examples of the aliphatic polyol include ethylene glycol, propylene glycol, butanediol, pentanediol, and hexanediol.

Examples of polyester polyols include polymers obtained by dehydration condensation of polybasic acids and polyhydric alcohols, polymers obtained by ring-opening polymerization of lactones such as ε-caprolactone and α-methyl-ε-caprolactone, and condensates of hydroxycarboxylic acids and the above-mentioned polyhydric alcohols.
Specific examples of polybasic acids include aliphatic acids such as adipic acid, azelaic acid, sebacic acid, and succinic acid; phthalic acids such as terephthalic acid, isophthalic acid, and orthophthalic acid; and aromatic acids such as trimellitic acid.
Specifically, the polyhydric alcohol used in the polyester polyol is preferably a dihydric alcohol (diol), more specifically, aromatic alcohols such as bisphenol A, and aliphatic alcohols such as ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexane glycol, neopentyl glycol, and polyoxyethylene glycol having an average molecular weight of 150 to 500 are listed.
Specific examples of hydroxycarboxylic acids include castor oil and reaction products of castor oil and ethylene glycol.

Examples of polyether polyols include those obtained by ring-opening addition polymerization of alkylene oxide (hereinafter abbreviated as AO) to an initiator having two or more active hydrogen atoms. Examples of AO include AOs having 2 to 6 carbon atoms, such as ethylene oxide (hereinafter abbreviated as EO), 1,2-propylene oxide (hereinafter abbreviated as PO), 1,3-propylene oxide, 1,2-butylene oxide, and 1,4-butylene oxide. Among these, PO, EO, and 1,2-butylene oxide are preferred from the viewpoint of properties and reactivity, and PO and EO are more preferred. When two or more AOs are used (for example, PO and EO), the addition method may be block addition or random addition, or a combination of these.

Examples of the initiator include diols such as ethylene glycol, propylene glycol, butylene glycol, and 1,6-hexanediol; Examples of the polyol include triols such as glycerin and trimethylolpropane; tetrahydric to octahydric alcohols such as pentaerythritol, sorbitol, mannitol, sorbitan, diglycerin, dipentaerythritol, sucrose, glucose, mannose, fructose, methyl glucoside, and derivatives thereof; phenols such as phenol, phloroglucine, cresol, pyrogallol, catechol, hydroquinone, bisphenol A, bisphenol F, bisphenol S, 1-hydroxynaphthalene, 1,3,6,8-tetrahydroxynaphthalene, anthrol, 1,4,5,8-tetrahydroxyanthracene, and 1-hydroxypyrene; polyols (e.g., having 2 to 100 functional groups) such as castor oil polyol, (co)polymers of hydroxyalkyl (meth)acrylate, and polyvinyl alcohol; and condensates of phenol and formaldehyde (novolaks).
The initiator may be an amine. Examples of the amine include alkanolamines such as monoethanolamine and diethanolamine, and diamines. Examples of the diamine include aliphatic amines such as alkylenediamines such as ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, and neopentyldiamine, and aromatic amines such as 2,4-toluenediamine, 2,6-toluenediamine, diethyltoluenediamine, 4,4'-diaminodiphenylmethane, p-phenylenediamine, o-phenylenediamine, and naphthalenediamine.

As the polyol component, it is preferable to use polyester polyols and polyether polyols. As the polyester polyol, from the viewpoint of flame retardancy, aromatic polyester polyols are preferable, among which polyester polyols obtained from aromatic polybasic acids and aliphatic polyhydric alcohols, particularly aliphatic diols, are preferable, and as the aromatic polybasic acids, various phthalic acids are more preferable.

[Polyisocyanate component]
As the polyisocyanate component forming the polyurethane foam, various polyisocyanate compounds having two or more isocyanate groups, such as aromatic, alicyclic, and aliphatic polyisocyanate compounds, can be used. Preferably, liquid diphenylmethane diisocyanate (MDI) is used because of ease of handling, rapid reaction, excellent physical properties of the resulting polyurethane foam, and low cost. Examples of liquid MDI include crude MDI (also called polymeric MDI). Specific examples of commercially available liquid MDI include "44V-10" and "44V-20" (manufactured by Sumika Covestro Urethane Co., Ltd.) and "Millionate MR-200" (Nippon Polyurethane Industry Co., Ltd.). In addition, uretonimine-containing MDI (for example, a commercially available product "Millionate MTL": manufactured by Nippon Polyurethane Industry Co., Ltd.) may also be used. In addition to liquid MDI, other polyisocyanate compounds may be used in combination, and as the polyisocyanate compounds to be used in combination, any polyisocyanate compound known in the technical field of polyurethanes can be used without any limitations.

The isocyanate index (NCO INDEX) in the polyurethane foam (polyurethane composition) is not particularly limited, but is preferably from 40 to 600, and more preferably from 100 to 500. From the viewpoint of improving flame retardancy, the isocyanate index is also preferably 200 or more.
Here, the isocyanate index means the equivalent ratio of the isocyanate groups of the polyisocyanate component to all active hydrogen groups contained in the polyurethane composition (water as a blowing agent is calculated as a bifunctional active hydrogen compound) expressed as a percentage (the equivalent ratio of isocyanate groups to 100 equivalents of active hydrogen groups).

[Foaming agent]
The polyurethane composition of the present invention contains a foaming agent as described above. Examples of the foaming agent include water, an organic physical foaming agent, and an inorganic physical foaming agent.
Examples of organic physical blowing agents include low-boiling point hydrocarbons such as propane, butane, pentane, hexane, heptane, cyclopropane, cyclobutane, cyclopentane, cyclohexane, and cycloheptane; chlorinated aliphatic hydrocarbon compounds such as dichloroethane, propyl chloride, isopropyl chloride, butyl chloride, isobutyl chloride, pentyl chloride, and isopentyl chloride; fluorine compounds such as trichloromonofluoromethane, _{trichlorotrifluoroethane} , CHF3, _CH2F2 , and _CH3F ; and ether compounds such as diisopropyl ether.
In addition, hydrofluorocarbon compounds and hydrofluoroolefin compounds can be mentioned. The hydrofluorocarbon compounds may be those containing chlorine atoms such as dichloromonofluoroethane (for example, HCFC141b (1,1-dichloro-1-fluoroethane)), HCFC22 (chlorodifluoromethane), and HCFC142b (1-chloro-1,1-difluoroethane), or may be HFC-245fa (1,1,1,3,3-pentafluoropropane), HFC-365mfc (1,1,1,3,3-pentafluorobutane), or may be the like. The hydrofluoroolefin compounds may be those containing chlorine such as chlorotrifluoropropene, chlorodifluoropropene, and chlorotrifluoropropene such as HFO-1233zd(E) (trans-1-chloro-3,3,3-trifluoropropene), and chlorotetrafluoropropene, or may be tetrafluoropropene, pentafluoropropene, or the like.
Examples of the inorganic physical foaming agent include nitrogen gas, oxygen gas, argon gas, and carbon dioxide gas.

As the blowing agent, it is preferable to use at least one selected from water, hydrofluorocarbons, and hydrofluoroolefins, and among these, it is preferable to use hydrofluoroolefins. In addition, the blowing agent can be used alone or in combination of two or more. When using two or more in combination, for example, two or more organic physical blowing agents may be used in combination, water and an organic physical blowing agent may be used in combination, or other combinations may be used, but preferably hydrofluoroolefins and water are used in combination.

The amount of the foaming agent in the polyurethane composition is not particularly limited, but is preferably in the range of 0.1 to 25 parts by mass, more preferably in the range of 1 to 20 parts by mass, even more preferably in the range of 3 to 17 parts by mass, and most preferably in the range of 5 to 14 parts by mass, relative to 100 parts by mass of the urethane resin. By making the amount of the foaming agent equal to or greater than these lower limits, foaming is promoted and the density of the resulting molded article can be reduced. On the other hand, by making the amount equal to or less than the upper limits, problems such as foam cells breaking and being unable to form a polyurethane foam can be prevented.
The urethane resin is a reaction product of a polyisocyanate component and a polyol component, and 100 parts by mass of the urethane resin means a total of 100 parts by mass of the polyisocyanate component and the polyol component in the polyurethane composition.

[Foam stabilizer]
The polyurethane composition preferably further contains a foam stabilizer. Examples of the foam stabilizer include polyoxyalkylene foam stabilizers such as polyoxyalkylene alkyl ethers, and surfactants such as silicone foam stabilizers such as organopolysiloxanes. The silicone foam stabilizer may also include a graft copolymer of polydimethylsiloxane and polyethylene glycol.
The amount of the foam stabilizer in the polyurethane composition is not particularly limited, but for example, it is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 4.0 parts by mass, and even more preferably 0.5 to 3.0 parts by mass, relative to 100 parts by mass of the urethane resin.
The foam stabilizer may be used alone or in combination of two or more kinds.

[catalyst]
The polyurethane composition preferably further contains a catalyst. The polyurethane composition may contain, as a catalyst, for example, a urethanization catalyst, a trimerization catalyst, or both of these, and preferably contains both of these.
The urethane catalyst is a catalyst that accelerates the reaction between the polyol component and the polyisocyanate. Specific examples of the urethane catalyst include amino compounds, tin compounds, bismuth compounds, and metal salts of acetylacetone.
Examples of the amino compound include pentamethyldiethylenetriamine, triethylamine, N-methylmorpholine bis(2-dimethylaminoethyl)ether, bis(2-dimethylaminoethyl)ether, N,N,N',N",N"-pentamethyldiethylenetriamine, N,N,N'-trimethylaminoethyl-ethanolamine, bis(2-dimethylaminoethyl)ether, N-methyl-N',N'-dimethylaminoethylpiperazine, imidazole compounds in which the secondary amine functional group in the imidazole ring is substituted with a cyanoethyl group, N,N-dimethylcyclohexylamine, diazabicycloundecene, triethylenediamine, tetramethylethylenediamine, tetramethylhexamethylenediamine, 1-methylimidazole, trimethylaminoethylpiperazine, and tripropylamine.
Examples of the tin compound include stannous octoate, dibutyltin diacetate, dibutyltin dilaurate, etc. Examples of the bismuth compound include bismuth neodecanoate, bismuth octoate, etc.
Examples of acetylacetone metal salts include acetylacetone aluminum, acetylacetone iron, acetylacetone copper, acetylacetone zinc, acetylacetone beryllium, acetylacetone chromium, acetylacetone indium, acetylacetone manganese, acetylacetone molybdenum, acetylacetone titanium, acetylacetone cobalt, acetylacetone vanadium, and acetylacetone zirconium.
The urethane resin curing catalyst may be used alone or in combination of two or more kinds.

There is no particular limit to the amount of urethane resin curing catalyst in the polyurethane composition, but it is preferably in the range of 0.3 to 10 parts by mass, more preferably in the range of 0.5 to 8 parts by mass, and even more preferably in the range of 1 to 5 parts by mass, per 100 parts by mass of urethane resin. By keeping it within the above range, the reaction between the polyol component and the polyisocyanate component can be promoted at an appropriate reaction speed, and the gel time can be easily adjusted within the desired range.

A trimerization catalyst is a catalyst that promotes trimerization to form an isocyanurate bond. By promoting trimerization of a polyurethane resin, the flame retardancy of a polyurethane foam is improved.
Examples of the trimerization catalyst that can be used include aromatic compounds such as tris(dimethylaminomethyl)phenol, 2,4-bis(dimethylaminomethyl)phenol, and 2,4,6-tris(dialkylaminoalkyl)hexahydro-S-triazine; alkali metal salts such as potassium acetate, sodium acetate, potassium 2-ethylhexanoate, sodium 2-ethylhexanoate, potassium octylate, and sodium octylate; aziridines such as 2-ethylaziridine; lead compounds such as lead naphthenate and lead octylate; alcoholate compounds such as sodium methoxide; phenolate compounds such as potassium phenoxide; tertiary ammonium salts such as trimethylammonium salts, triethylammonium salts, and triphenylammonium salts; and quaternary ammonium salts such as tetramethylammonium salts, tetraethylammonium, and tetraphenylammonium salts.
The trimerization catalyst may be used alone or in combination of two or more kinds.

The amount of the trimerization catalyst is not particularly limited, but is preferably in the range of 0.5 to 12 parts by mass, more preferably in the range of 1 to 9 parts by mass, and even more preferably in the range of 2 to 7 parts by mass, relative to 100 parts by mass of the urethane resin. By setting the amount of the trimerization catalyst within the above range, isocyanurate bonds are appropriately formed, and flame retardancy is improved.
Furthermore, from the viewpoint of improving the curing speed and flame retardancy of the urethane, the total amount of the catalyst is preferably 0.5 to 15 parts by mass, more preferably 1 to 10 parts by mass, and even more preferably 1.5 to 8 parts by mass, per 100 parts by mass of the urethane resin.

[Flame retardant]
It is preferable that the polyurethane foam, i.e., the polyurethane composition, contains a flame retardant. More preferably, the flame retardant contained in the polyurethane foam contains at least one selected from red phosphorus, phosphate ester, phosphate-containing flame retardant, bromine-containing flame retardant, boron-containing flame retardant, antimony-containing flame retardant, and metal hydroxide. The use of such a flame retardant makes it easier to impart non-flammability and flame retardancy to the polyurethane foam.
The flame retardant to be blended in the polyurethane composition preferably contains red phosphorus from the viewpoints of flame retardancy and non-combustibility, and preferably contains a phosphate ester from the viewpoints of handleability, and more preferably contains both red phosphorus and a phosphate ester from the viewpoints of flame retardancy, non-combustibility, and handleability.
It is more preferable to use at least one selected from the group consisting of a phosphate-containing flame retardant, a bromine-containing flame retardant, a boron-containing flame retardant, an antimony-containing flame retardant, and a metal hydroxide in addition to red phosphorus or red phosphorus and a phosphate ester.

(Red phosphorus)
There is no limitation on the red phosphorus used in the present invention, and a commercially available product can be appropriately selected and used. The red phosphorus does not need to be blended as a single red phosphorus, and may be appropriately surface-treated.
The amount of red phosphorus in the polyurethane foam is preferably in the range of 3.0 to 18 parts by mass, more preferably 4.0 to 12 parts by mass, per 100 parts by mass of the urethane resin. By making the amount of red phosphorus 3.0 parts by mass or more, the self-extinguishing property of the polyurethane foam is maintained, and it becomes easier to impart non-flammability to the polyurethane foam. In addition, by making the amount 18 parts by mass or less, the foaming of the polyurethane composition is not inhibited.

(Phosphate ester)
The phosphate ester is not particularly limited, but it is preferable to use a monophosphate ester, a condensed phosphate ester, etc. A monophosphate ester is a compound having one phosphorus atom in the molecule.
The monophosphate ester is not particularly limited, and examples thereof include trimethyl phosphate, triethyl phosphate, tributyl phosphate, tri(2-ethylhexyl)phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, tris(isopropylphenyl)phosphate, tris(phenylphenyl)phosphate, trinaphthyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, diphenyl phosphate, Examples of the acryloyloxyethyl phosphate include diphenyl(2-ethylhexyl)phosphate, di(isopropylphenyl)phenyl phosphate, monoisodecyl phosphate, 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, melamine phosphate, dimelamine phosphate, melamine pyrophosphate, and tris(β-chloropropyl)phosphate.

The condensed phosphate ester is not particularly limited, but examples thereof include condensed phosphate esters such as trialkyl polyphosphate, resorcinol polyphenyl phosphate, resorcinol poly(di-2,6-xylyl) phosphate (manufactured by Daihachi Chemical Industry Co., Ltd., product name PX-200), hydroquinone poly(2,6-xylyl) phosphate, and condensates thereof.
Examples of commercially available condensed phosphate esters include resorcinol polyphenyl phosphate (product name: CR-733S), bisphenol A polycresyl phosphate (product name: CR-741), aromatic condensed phosphate ester (product name: CR747), resorcinol polyphenyl phosphate (manufactured by ADEKA Corporation, product name: Adeka STAB PFR), and bisphenol A polycresyl phosphate (product names: FP-600, FP-700).

Among the above, it is preferable to use monophosphate esters because they are highly effective in reducing the viscosity of the composition before curing and in reducing the initial heat generation, and it is more preferable to use tris(β-chloropropyl)phosphate. The phosphate esters may be used alone or in combination of two or more.

The amount of the phosphate ester blended is preferably in the range of 1.5 to 52 parts by mass, more preferably in the range of 1.5 to 20 parts by mass, even more preferably in the range of 2.0 to 15 parts by mass, and most preferably in the range of 2.0 to 13 parts by mass, relative to 100 parts by mass of the urethane resin.
By making the amount of the phosphoric ester 1.5 parts by mass or more, it is possible to prevent cracking of dense residue formed from the polyurethane foam in the event of a fire, and by making the amount of the phosphoric ester 52 parts by mass or less, foaming of the polyurethane composition is not inhibited. In addition, by making the amount of the phosphoric ester within the above range, it is easy to impart non-flammability and flame retardancy.

(Phosphate-containing flame retardants)
Examples of the phosphate-containing flame retardant include phosphates consisting of a salt of phosphoric acid and at least one metal or compound selected from the group consisting of metals in Groups IA to IVB of the periodic table, ammonia, aliphatic amines, and aromatic amines.
The phosphoric acid is not particularly limited, and examples thereof include various phosphoric acids such as monophosphoric acid, pyrophosphoric acid, and polyphosphoric acid.
Examples of the metals in Groups IA to IVB of the periodic table include lithium, sodium, calcium, barium, iron (II), iron (III), aluminum, etc. Examples of the aliphatic amines include methylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, piperazine, etc. Examples of the aromatic amines include pyridine, triazine, melamine, ammonium, etc.
The above-mentioned phosphate-containing flame retardants may be subjected to a known water resistance improving treatment, such as treatment with a silane coupling agent or coating with a melamine resin.

Specific examples of phosphate-containing flame retardants include monophosphates, pyrophosphates, polyphosphates, and the like.
The monophosphate salt is not particularly limited, and examples thereof include ammonium salts such as ammonium phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate; sodium salts such as monosodium phosphate, disodium phosphate, trisodium phosphate, monosodium phosphite, disodium phosphite, and sodium hypophosphite; potassium salts such as monopotassium phosphate, dipotassium phosphate, tripotassium phosphate, monopotassium phosphite, dipotassium phosphite, and potassium hypophosphite; lithium salts such as monolithium phosphate, dilithium phosphate, trilithium phosphate, monolithium phosphite, dilithium phosphite, and lithium hypophosphite; barium salts such as barium dihydrogen phosphate, barium hydrogen phosphate, tribarium phosphate, and barium hypophosphite; magnesium salts such as monohydrogen magnesium phosphate, magnesium hydrogen phosphate, trimagnesium phosphate, and magnesium hypophosphite; calcium salts such as calcium dihydrogen phosphate, calcium hydrogen phosphate, tricalcium phosphate, and calcium hypophosphite; and zinc salts such as zinc phosphate, zinc phosphite, and zinc hypophosphite.

The polyphosphate is not particularly limited, but examples thereof include ammonium polyphosphate, piperazine polyphosphate, melamine polyphosphate, ammonium amide polyphosphate, and aluminum polyphosphate.
Among these, it is preferable to use monophosphates, and it is more preferable to use ammonium dihydrogen phosphate, since this improves the self-extinguishing property of the phosphate-containing flame retardant.
The phosphate-containing flame retardants may be used alone or in combination of two or more.

The amount of the phosphate-containing flame retardant is preferably in the range of 1.5 to 52 parts by mass, more preferably in the range of 1.5 to 20 parts by mass, even more preferably in the range of 2.0 to 15 parts by mass, and most preferably in the range of 2.0 to 10 parts by mass, relative to 100 parts by mass of the urethane resin.
When the amount of the phosphate-containing flame retardant is 1.5 parts by mass or more, the self-extinguishing property of the polyurethane foam is maintained and fire resistance is easily imparted, while when the amount is 52 parts by mass or less, foaming of the polyurethane composition is not inhibited.

(Bromine-containing flame retardants)
The bromine-containing flame retardant is not particularly limited as long as it is a compound containing bromine in its molecular structure, and examples thereof include aromatic brominated compounds.
Specific examples of aromatic brominated compounds include monomeric organic bromine compounds such as hexabromobenzene, pentabromotoluene, hexabromobiphenyl, decabromobiphenyl, hexabromocyclodecane, decabromodiphenyl ether, octabromodiphenyl ether, hexabromodiphenyl ether, bis(pentabromophenoxy)ethane, ethylene-bis(tetrabromophthalimide), and tetrabromobisphenol A.
Further examples of the brominated epoxy compound include brominated epoxy compounds such as polycarbonate oligomers produced using brominated bisphenol A as a raw material, and copolymers of polycarbonate oligomers and bisphenol A; diepoxy compounds produced by the reaction of brominated bisphenol A with epichlorohydrin; and monoepoxy compounds obtained by the reaction of brominated phenols with epichlorohydrin; poly(brominated benzyl acrylate), brominated polyphenylene ether, brominated bisphenol A, condensates of cyanuric chloride and brominated phenol, brominated (polystyrene), poly(brominated styrene), brominated polystyrenes such as crosslinked brominated polystyrene, and crosslinked or non-crosslinked brominated poly(methylstyrene).
From the viewpoint of controlling the amount of heat generated in the early stage of combustion, brominated polystyrene, hexabromobenzene, and the like are preferred, with hexabromobenzene being more preferred.
The bromine-containing flame retardants may be used alone or in combination of two or more.

The blending amount of the bromine-containing flame retardant used in the present invention is preferably in the range of 1.5 to 52 parts by mass, more preferably in the range of 1.5 to 20 parts by mass, even more preferably in the range of 2.0 to 15 parts by mass, and most preferably in the range of 2.0 to 10 parts by mass, relative to 100 parts by mass of the urethane resin.
When the amount of the bromine-containing flame retardant is 1.5 parts by mass or more, the self-extinguishing property of the polyurethane foam is maintained and fire resistance is easily imparted, while when the amount is 52 parts by mass or less, foaming of the polyurethane composition is not inhibited.

(Boron-containing flame retardants)
Boron-containing flame retardants include borax, boron oxide, boric acid, and borates.
Examples of boron oxide include diboron trioxide, boron trioxide, diboron dioxide, tetraboron trioxide, and tetraboron pentoxide.
Examples of borates include borates of alkali metals, alkaline earth metals, elements of Groups 4, 12, and 13 of the periodic table, and ammonium.
Specific examples of the borate include alkali metal borate such as lithium borate, sodium borate, potassium borate, and cesium borate; alkaline earth metal borate such as magnesium borate, calcium borate, and barium borate; zirconium borate, zinc borate, aluminum borate, and ammonium borate.
Preferably, the boron-containing flame retardant is a borate, more preferably zinc borate.
The boron-containing flame retardants may be used alone or in combination of two or more.

The amount of the boron-containing flame retardant is preferably in the range of 1.5 to 52 parts by mass, more preferably in the range of 1.5 to 20 parts by mass, even more preferably in the range of 2.0 to 15 parts by mass, and most preferably in the range of 2.0 to 10 parts by mass, relative to 100 parts by mass of the urethane resin.
When the amount of the boron-containing flame retardant is 1.5 parts by mass or more, the self-extinguishing property of the polyurethane foam is maintained and fire resistance is easily imparted, while when the amount is 52 parts by mass or less, foaming of the polyurethane composition is not inhibited.

(Antimony-containing flame retardants)
Examples of the antimony-containing flame retardant used in the present invention include antimony oxide, antimonates, and pyroantimonates.
Examples of antimony oxides include antimony trioxide and antimony pentoxide. Examples of antimonate salts include sodium antimonate and potassium antimonate. Examples of pyroantimonate salts include sodium pyroantimonate and potassium pyroantimonate.
Preferably, the antimony-containing flame retardant is antimony oxide.
The antimony-containing flame retardants may be used alone or in combination of two or more.

The amount of antimony-containing flame retardant is preferably in the range of 1.5 to 52 parts by mass, more preferably in the range of 1.5 to 20 parts by mass, even more preferably in the range of 2.0 to 15 parts by mass, and most preferably in the range of 2.0 to 10 parts by mass, per 100 parts by mass of urethane resin. If the amount of antimony-containing flame retardant is 1.5 parts by mass or more, the self-extinguishing properties of the polyurethane foam are maintained and fire resistance is easily imparted. Furthermore, if it is 52 parts by mass or less, the foaming of the polyurethane composition is not inhibited.

(Metal hydroxide)
Examples of metal hydroxides include magnesium hydroxide, calcium hydroxide, aluminum hydroxide, iron hydroxide, nickel hydroxide, zirconium hydroxide, titanium hydroxide, zinc hydroxide, copper hydroxide, vanadium hydroxide, tin hydroxide, etc. The metal hydroxides may be used alone or in combination of two or more.

The amount of metal hydroxide is preferably in the range of 1.5 to 52 parts by mass, more preferably 1.5 to 20 parts by mass, even more preferably 2.0 to 15 parts by mass, and most preferably 2.0 to 10 parts by mass, per 100 parts by mass of urethane resin. When the amount of metal hydroxide is 1.5 parts by mass or more, the self-extinguishing properties of the polyurethane foam are maintained and fire resistance is easily imparted. Furthermore, when the amount is 52 parts by mass or less, foaming of the polyurethane composition is not inhibited.

Preferred combinations of the flame retardants include, for example, any of the following (a) to (n), and among these, a combination containing at least red phosphorus and a phosphate ester is preferred.
(a) Red phosphorus and phosphate esters
(b) Red phosphorus and phosphate-containing flame retardants
(c) Red phosphorus and bromine-containing flame retardants
(d) Red phosphorus and boron-containing flame retardants
(e) Red phosphorus and antimony-containing flame retardants
(f) Red phosphorus and metal hydroxides
(g) Red phosphorus, phosphate esters and phosphate-containing flame retardants
(h) Red phosphorus, phosphate esters and bromine-containing flame retardants
(i) Red phosphorus, phosphate esters and boron-containing flame retardants
(j) Red phosphorus, phosphate-containing flame retardants and bromine-containing flame retardants
(k) Red phosphorus, phosphate-containing flame retardants and boron-containing flame retardants
(l) Red phosphorus, bromine-containing flame retardants and boron-containing flame retardants
(m) Red phosphorus, phosphate esters, phosphate-containing flame retardants and bromine-containing flame retardants
(n) Red phosphorus, phosphate esters, phosphate-containing flame retardants, bromine-containing flame retardants and boron-containing flame retardants

The total amount of the flame retardant is preferably in the range of 4.5 to 70 parts by mass, more preferably in the range of 8 to 40 parts by mass, even more preferably in the range of 10 to 30 parts by mass, and most preferably in the range of 12 to 25 parts by mass, relative to 100 parts by mass of the urethane resin.
When the amount of the flame retardant is 4.5 parts by mass or more, the polyurethane foam is easily rendered non-flammable. In addition, the dense residue formed from the polyurethane foam can be prevented from cracking in the event of a fire. When the amount is 70 parts by mass or less, the foaming of the polyurethane composition is less likely to be inhibited by the flame retardant.

[Inorganic filler]
The polyurethane composition may contain needle-shaped fillers or inorganic fillers other than the needle-shaped fillers. Examples of needle-shaped fillers include potassium titanate whiskers, magnesium-containing whiskers, silicon-containing whiskers, wollastonite, sepiolite, zonolite, elestadite, boehmite, rod-shaped hydroxyapatite, glass fibers, asbestos fibers, carbon fibers, graphite fibers, metal fibers, slag fibers, gypsum fibers, silica fibers, alumina fibers, silica-alumina fibers, zirconia fibers, boron nitride fibers, boron fibers, and stainless steel fibers. In addition to the flame retardant, the needle-shaped fillers are blended to improve flame retardancy, non-combustibility, and the like. The needle-shaped fillers may be used alone or in combination of two or more.

The amount of needle filler in the polyurethane composition is not particularly limited, but is preferably in the range of 3.0 to 30 parts by mass, more preferably 3.0 to 20 parts by mass, even more preferably 3.0 to 18 parts by mass, and most preferably 6.0 to 18 parts by mass, relative to 100 parts by mass of the urethane resin.
When the amount of the needle-like filler is 3.0 parts by mass or more, the shape of the polyurethane foam after combustion is easily maintained, and when the amount is 30 parts by mass or less, the needle-like filler is less likely to inhibit the foaming of the polyurethane foam.

Examples of inorganic fillers other than the above-mentioned acicular filler include silica, diatomaceous earth, alumina, titanium oxide, calcium oxide, magnesium oxide, iron oxide, tin oxide, antimony oxide, ferrites, basic magnesium carbonate, calcium carbonate, magnesium carbonate, zinc carbonate, barium carbonate, dawsonite, hydrotalcite, calcium sulfate, barium sulfate, gypsum fiber, potassium salts of calcium silicate and the like, talc, clay, mica, montmorillonite, bentonite, activated clay, seviolite, imogolite, sericite, glass fiber, glass beads, silica balloon, aluminum nitride, boron nitride, silicon nitride, carbon black, graphite, carbon fiber, carbon balloon, charcoal powder, various metal powders, potassium titanate, magnesium sulfate, lead zirconate titanate, aluminum borate, molybdenum sulfide, silicon carbide, various magnetic powders, and fly ash.
The inorganic fillers may be used alone or in combination of two or more.

[Other additives]
The polyurethane composition may further contain additives other than those mentioned above, such as phenol-based, amine-based, sulfur-based and other antioxidants, heat stabilizers, metal damage inhibitors, antistatic agents, stabilizers, crosslinking agents, lubricants, softeners, pigments, additives such as tackifying resins, and tackifiers such as polybutene and petroleum resins.

As described above, the polyurethane foam of the present invention is produced by obtaining a polyurethane composition containing a polyol component, a polyisocyanate component, and a blowing agent, reacting the polyol component and the polyisocyanate component, and foaming the polyurethane composition. In this case, as described above, it is preferable to prepare a polyol liquid containing a polyol component and a polyisocyanate liquid containing a polyisocyanate component and mix them to obtain a polyurethane composition.

The polyol liquid typically contains a foaming agent in addition to the polyol component. In addition, when a component other than the foaming agent is blended into the polyurethane composition, it is preferable to include the component in the polyol liquid. Therefore, it is preferable that the polyol liquid contains at least one selected from a foam stabilizer, a catalyst, a flame retardant, an inorganic filler, and other additives other than these, in addition to the foaming agent.
The polyol component has high stability against blowing agents and various additives, and even if a blowing agent or additives is blended into the polyol liquid, the raw material of the polyurethane foam can be prevented from deteriorating over time. On the other hand, the polyisocyanate liquid is usually preferably composed of a single polyisocyanate component, but may contain additives as appropriate as long as the polyisocyanate component does not deteriorate.

The viscosity of the polyol liquid at 20°C is not particularly limited, but is preferably 2000 mPa·s or less, and more preferably 1000 mPa·s or less. By setting the viscosity of the polyol liquid to the above upper limit or less, the fluidity of the polyurethane composition is improved, making it easier to spread the polyurethane foam throughout the entire cavity. The viscosity of the polyol liquid is preferably 100 mPa·s or more, more preferably 200 mPa·s or more. The viscosity of the polyol liquid can be appropriately adjusted, for example, depending on the molecular weight of the polyol component used. The viscosity of the polyol liquid was measured using a B-type viscometer at a temperature of 20°C.

The gel time of the polyurethane composition is preferably 15 seconds or less. The gel time is the time required for gelation when the polyol liquid agent and the polyisocyanate liquid agent are mixed at 10°C. When the gel time is 15 seconds or less, the polyurethane composition can be reacted and foamed immediately at room temperature after being injected into the cavity. Therefore, the polyurethane foam can be filled into the cavity with high workability. From the above viewpoint, the gel time is more preferably 10 seconds or less.
Moreover, from the viewpoint of preventing hardening before injection into the cavity, the gel time is preferably 1 second or more, and more preferably 3 seconds or more.
The method for adjusting the gel time of the polyurethane composition is not particularly limited, but it is preferable to use a urethanization catalyst and adjust the amount of the catalyst appropriately. In addition, the gel time can be shortened as described above by using a polyol component with a small molecular weight or a polyol component with a large hydroxyl value.

The density of the polyurethane foam is not particularly limited, but is preferably in the range of 20 to 200 kg/ ^m3 . By making the density 200 kg/ ^m3 or less, the polyurethane foam becomes lightweight, and it becomes easier to install a structure in which the polyurethane foam is filled in the cavity inside a building. In addition, by making the density 20 kg/ ^m3 or more, it becomes easier to exhibit the desired flame retardancy and non-combustibility. From these viewpoints, the density of the polyurethane foam is more preferably in the range of 25 to 100 kg/ ^m3 , and even more preferably in the range of 30 to 80 kg/ ^m3 . The density of the polyurethane foam can be measured in accordance with JIS K7222.

The polyurethane foam obtained can be imparted with at least one of flame retardancy, semi-nonflammability, and nonflammability. More specifically, the polyurethane foam is preferably one that has a total heat generation amount of 8 MJ/m2 ^or less after 5 minutes when heated at a radiant heat intensity of 50 kW/ ^m2 in accordance with the ISO-5660 test method. More preferably, one that has a total heat generation amount of 8 MJ/m2 or ^less after 10 minutes is used, and even more preferably, one that has a total heat generation amount of 8 MJ/m2 or ^less after 20 minutes is used.

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

The methods for measuring the physical properties and characteristics of the polyurethane foam are as follows.
[Gel time]
The polyol solution and the polyisocyanate solution, both adjusted to 10° C., were mixed and stirred for 1 second with a stirrer rotating at 8,000 rpm, and the gel time of the foamed polyurethane foam was measured. The gel time was measured from the start of stirring, and was defined as the time when the foam started to form strings when a glass rod was inserted into the top of the foam during foaming, or the time when it could no longer be inserted.
[Total heat generation]
The fire resistance of the polyurethane foam was evaluated by the following method. The polyurethane foam was cut into a length of 10 cm, a width of 10 cm, and a thickness of 5 cm to prepare a cone calorimeter test sample. The cone calorimeter test sample was heated for 5, 10, and 20 minutes at a radiant heat intensity of 50 kW/ ^m2 in accordance with the ISO-5660 test method, and the total heat generation amount after 5, 10, and 20 minutes was measured to evaluate the fire resistance.

[Example 1]
As the structure, a frame material with a rectangular cross section of 40 mm × 25 mm and a rectangular tubular cross section having a 100 cm long cavity was prepared as shown in Figure 3. Both ends of the frame material were blocked with other frame materials, and injection holes with a diameter of 10 mm that communicated with the cavity were formed in the frame material at 20 cm intervals. There were a total of five injection holes.
A polyol liquid was prepared according to the formulation in Table 1. The polyol liquid and the polyisocyanate component (polyisocyanate liquid) were mixed using a mixer/injector (GRACO, product name "H-25") equipped with a spray gun to obtain a polyurethane composition having the formulation shown in Table 1, and the polyurethane composition was injected into the cavity through the injection hole by the spray gun. Inside the cavity, the polyurethane composition reacted and expanded to become a polyurethane foam. The polyol liquid and the polyisocyanate component were mixed in the mixer/injector while being maintained at 40°C to obtain the polyurethane composition.
The polyurethane composition was injected into the cavity from each injection hole for 1 to 2 seconds. The holes into which the polyurethane composition was injected were changed in sequence. The polyurethane composition started to foam immediately after injection, and as soon as the injection of the polyurethane composition from all the injection holes was completed, the entire inside of the cavity was filled with polyurethane foam.

[Example 2]
The same procedure as in Example 1 was carried out, except that the formulations of the polyol liquid, polyisocyanate component (polyisocyanate liquid), and polyurethane composition were changed as shown in the following Table 2. The polyurethane composition started to foam immediately after injection, and as soon as the injection of the polyurethane composition from all the injection holes was completed, the entire inside of the cavity was filled with polyurethane foam.

The components in Tables 1 and 2 are as follows.
(Polyol Component)
Polyol component 1: p-phthalic acid-based polyester polyol (manufactured by Kawasaki Chemical Industries, Ltd., product name: Maximol RFK-505, hydroxyl value: 250 mg KOH/g, number of functional groups: 2 [per molecule])
Polyol component 2: Aromatic polyester polyol (manufactured by Kawasaki Chemical Industries, Ltd., product name: Maximol RDK-133, hydroxyl value: 315 mg KOH/g, number of functional groups: 2 [per molecule])
(Foaming Agent)
Blowing agent (water): Water Blowing agent (HFO): 1233zd(E) (manufactured by Honeywell, product name: Solstice LBA)
(Foam stabilizer)
Foam stabilizer: Polyalkylene glycol foam stabilizer (manufactured by Toray Dow Corning Co., Ltd., product name: SH-193)
(catalyst)
Catalyst 1: Urethane catalyst, pentamethyldiethylenetriamine (manufactured by Tosoh Corporation, product name: TOYOCAT-DT)
Catalyst 2: Trimerization catalyst, potassium octoate (manufactured by Ele Corporation, product name "Pelcat 9540")
Catalyst 3: Trimerization catalyst, manufactured by Tosoh Corporation, product name: TOYOCAT-TR20
Catalyst 4: Urethane catalyst, 1-methylimidazole, manufactured by Kao Corporation, product name: Kao No. 110
Catalyst 5: Urethane catalyst, bismuth octylate, manufactured by Nippon Kagaku Sangyo Co., Ltd., product name: PUCAT 25
(Flame retardant)
TMCPP: Tris(β-chloropropyl)phosphate (manufactured by Daihachi Chemical Industry Co., Ltd., product name: TMCPP)
Red phosphorus: manufactured by Rinkagaku Kogyo Co., Ltd., product name: Nova Excel 140
Zinc borate: manufactured by Rio Tinto Minerals Asia, product name: FireBrake ZB
(Polyisocyanate component)
Polyisocyanate component: Polymeric MDI (product name "Sumidur 44V-20", manufactured by Sumika Covestro Urethane Co., Ltd.)

[Comparative Example 1]
The same procedure was carried out as in Example 1, except that a single injection hole was formed near only one end of the frame material. Even when the polyurethane composition was continuously injected through the injection hole, the polyurethane foam did not permeate the entire cavity, and the entire cavity could not be filled with the polyurethane foam.

10, 20 Panel (structure)
14, 24, 34 Cavity 15A, 15B, 25A to 25E, 35A to 35E Injection hole 30 Frame material (structure)
60 Mixing and injecting device 61 First container 62 Second container 63 Mixing section 68 Spray gun

Claims (6)

A structure is prepared, the structure having a cavity therein and a plurality of injection holes communicating with the cavity;
injecting a polyurethane composition into the cavity through the plurality of injection holes with a spray gun, and foaming the polyurethane composition in the cavity to fill the cavity with a polyurethane foam;
The polyurethane composition comprises a polyisocyanate component, a polyol component, a blowing agent, a catalyst, and a flame retardant;
the polyol component comprises a polyester polyol;
The blowing agent contains water and a hydrofluoroolefin;
the catalyst contains a trimerization catalyst and a urethanization catalyst, the content of the trimerization catalyst is 0.5 to 12 parts by mass and the content of the urethanization catalyst is 0.3 to 10 parts by mass relative to 100 parts by mass of the total amount of the polyisocyanate component and the polyol component,
the flame retardant comprises at least one selected from the group consisting of red phosphorus, a phosphate ester, a phosphate-containing flame retardant, a bromine-containing flame retardant, a boron-containing flame retardant, an antimony-containing flame retardant, and a metal hydroxide;
The polyisocyanate component is a polyisocyanate liquid agent, and the components other than the polyisocyanate component are a polyol liquid agent,
The polyurethane composition is obtained by mixing a polyol liquid agent and a polyisocyanate liquid agent,
A method for producing a polyurethane foam-filled structure, wherein the viscosity of the polyol liquid at 20° C. is 2000 mPa·s or less, or the gel time of the polyurethane composition is 15 seconds or less. The method for producing a polyurethane foam-filled structure according to claim 1, wherein the polyol liquid and the polyisocyanate liquid are mixed in a mixing and injection device equipped with the spray gun, and the polyurethane composition obtained by mixing is discharged from the spray gun. The method for manufacturing a polyurethane foam-filled structure according to claim 1 or 2, wherein the structure has an elongated cavity inside. The method for producing a polyurethane foam-filled structure according to any one of claims 1 to 3, further comprising sealing the injection hole after injecting the polyurethane composition. The method for producing a polyurethane foam filled structure according to any one of claims 1 to 4 , wherein the polyurethane foam has a density of 20 to 200 kg/ ^m3 . The method for producing a polyurethane foam-filled structure according to any one of claims 1 to ⁵ , wherein the polyurethane foam has a total heat generation amount of 8 MJ/m2 or less after 5 minutes when heated at a radiant heat intensity ^of 50 kW/m2 in accordance with the test method of ISO-5660.