JP7769030B2 - Foamable urethane resin composition - Google Patents

Description

The present invention relates to a foamable urethane resin composition.

Polyurethane foams, taking advantage of their excellent insulating properties, are used to insulate and prevent condensation on ceilings, roofs, and walls of buildings such as apartment complexes, detached houses, and commercial buildings. Although polyurethane foams are lightweight, they are organic and therefore flammable. To address this issue, polyurethane foams containing flame retardants and other additives are used to enhance their flame resistance. For example, Patent Document 1 describes a flame-retardant polyurethane foam obtained using ammonium polyphosphate, a urea derivative, a polyol, and an isocyanate, characterized in that the flame-retardant polyurethane foam is obtained by using 5 to 150 parts by weight of ammonium polyphosphate and 0.001 to 15 parts by weight of a urea derivative per 100 parts by weight of polyol.

JP 2015-151524 A

In recent years, there have been a relatively large number of fires reported due to polyurethane foams used as thermal insulation in buildings. To alleviate this problem, it is desirable to develop polyurethane foams that not only have excellent flame retardancy but also have the property of being less susceptible to the spread of fire once a fire breaks out.
However, polyurethane foams can be prone to shrinkage depending on the environment in which they are used, which can affect the strength, thermal conductivity, and other properties of the foam, making it difficult to use for long periods of time.
Therefore, an object of the present invention is to provide a foamable urethane resin composition for producing a polyurethane foam that is resistant to shrinkage and fire spread.

As a result of extensive investigation, the present inventors have found that the above-mentioned problems can be solved by a foamable urethane resin composition containing a polyol compound and a polyisocyanate compound, wherein the polyol compound contains a polyol containing resin microparticles, and the foamable urethane resin composition exhibits a specific value in a hot steel ball test, and have completed the present invention. That is, the present invention provides the following [1] to [14].
[1] A foamable urethane resin composition comprising a polyol compound, a polyisocyanate compound, a flame retardant that is liquid at room temperature, a blowing agent, and a catalyst, wherein the polyol compound comprises a polyol containing resin microparticles, and wherein a steel ball sinks into a polyurethane foam made from the foamable urethane resin composition by a distance of 10 mm or less in a hot steel ball test described below.
(Hot steel ball evaluation)
(1) The polyurethane foam is cut into a cube with sides of 50 mm to be used as a test specimen.
(2) A wire mesh is placed 30 mm from the burner port of a Bunsen burner (outer flame length 70 mm), and a steel ball with a diameter of 10.0 mm and a weight of 4.15 g is placed on the wire mesh. The steel ball is heated for at least 5 minutes or more until the entire steel ball turns red, and the temperature of the steel ball reaches 630°C.
(3) In an atmosphere of 23°C, the steel ball heated in (2) above is immediately placed on the center of the upper part of the test piece in (1) above and left to stand until the steel ball has completely sunk in. Next, the cross section of the sufficiently cooled test piece is cut and the sinking distance and fusion diameter distance of the steel ball are measured.
[2] The foamable urethane resin composition according to the above [1], wherein the steel ball sinking distance in the hot steel ball evaluation is 5 mm or less and the melt diameter distance is 15 mm or less.
[3] The foamable urethane resin composition according to [1] or [2] above, wherein a polyurethane foam made from the foamable urethane resin composition has a total calorific value of 8 MJ/m2 ^{or less} when heated for 5 minutes at a radiant heat intensity of 50 kW/ ^m2 in accordance with the ISO-5660 test method.
[4] The foamable urethane resin composition according to any one of [1] to [3] above, wherein a polyurethane foam made from the foamable urethane resin composition has a maximum heat release rate of 200 kW/m2 or ^less when heated for 5 minutes at a radiant heat intensity of 50 kW/ ^m2 in accordance with the ISO-5660 test method.
[5] The foamable urethane resin composition according to any one of [1] to [4] above, wherein the resin fine particle-containing polyol is an amine-based polyether polyol containing resin fine particles.
[6] The foamable urethane resin composition according to any one of [1] to [5] above, wherein the resin microparticles are a polymer of at least one monomer selected from the group consisting of acrylonitrile, methacrylonitrile, fluorinated acrylonitrile, α-ethyl acrylonitrile, styrene, vinyl acetate, and acrylic monomers.
[7] The foamable urethane resin composition according to any one of [1] to [6] above, wherein the foamable urethane resin composition comprises a polyol composition containing a polyol compound, a flame retardant that is liquid at room temperature, a blowing agent, and a catalyst, and a polyisocyanate compound, and the content of the resin microparticles based on the total amount of the polyol composition is 0.01 mass% or more.
[8] The foamable urethane resin composition according to any one of [1] to [7] above, wherein the polyol compound contains a phthalic acid-based polyester polyol.
[9] The foamable urethane resin composition according to the above [8], wherein the weight ratio of the phthalic acid-based polyester polyol to the polyol containing resin microparticles (phthalic acid-based polyester polyol/polyol containing resin microparticles) is 95/5 to 55/45.
[10] The foamable urethane resin composition according to any one of [1] to [9] above, wherein the foaming agent contains water, and the content of the water is 1.5 parts by mass or less per 100 parts by mass of the polyol compound.
[11] The foamable urethane resin composition according to any one of the above [1] to [10], wherein the foaming agent contains a hydrofluoroolefin.
[12] The foamable urethane resin composition according to any one of [1] to [11] above, wherein the catalyst contains a trimerization catalyst.
[13] The foamable urethane resin composition according to any one of [1] to [12] above, having an isocyanate index of 150 to 700.
[14] The foamable urethane resin composition according to any one of the above [1] to [13], which is substantially free of inorganic fillers.

The present invention provides a foamable urethane resin composition that can form polyurethane foam that is resistant to shrinkage and fire spread in the event of a fire.

[Foamable urethane resin composition]
The foamable urethane resin composition of the present invention is a foamable urethane resin composition comprising a polyol compound, a polyisocyanate compound, a flame retardant that is liquid at room temperature, a blowing agent, and a catalyst, wherein the polyol compound comprises a polyol containing resin microparticles, and the polyurethane foam made from the foamable urethane resin composition exhibits a steel ball sinking distance of 10 mm or less in the hot steel ball test described below.
(Hot steel ball evaluation)
(1) The polyurethane foam is cut into a cube with sides of 50 mm to be used as a test specimen.
(2) A wire mesh was placed 30 mm from the burner port of a Bunsen burner (outer flame length 70 mm), and a steel ball with a diameter of 10.0 mm and a weight of 4.15 g was placed on the wire mesh. The steel ball was heated for at least 5 minutes or more until the entire steel ball turned red, bringing the steel ball temperature to 630°C. The steel ball temperature was measured by moving the heated steel ball from the wire mesh to another table that would not affect the radiation temperature measurement. The steel ball temperature was measured using a radiation thermometer (Keyence: FT-H40K). The radiation coefficient of the steel ball used was 0.45, and the value displayed on the radiation thermometer divided by 0.45 was used as the evaluation temperature (630°C). Brand new steel balls were used.
(3) In an atmosphere of 23°C, the steel ball heated in (2) above is immediately placed on the center of the upper part of the test piece in (1) above and left to stand until the steel ball has completely sunk in. Next, the cross section of the sufficiently cooled test piece is cut and the sinking distance and fusion diameter distance of the steel ball are measured.
In this hot steel ball evaluation, the time from heating the steel ball to measuring the temperature was within 1 second, and the steel ball was placed on the test piece immediately after the temperature was measured. Therefore, the above steel ball temperature (630°C) can be considered to be the temperature of the steel ball when it was placed on the test piece.

In the above-mentioned hot steel ball evaluation, as long as the diameter and weight of the steel ball are 10.0±0.5 mm, the weight is 4.15±0.3 g, and the steel ball temperature is within a range of 600 to 650°C as measured by a radiation thermometer, and the other conditions are as described above, an equivalent hot steel ball evaluation can be obtained, and therefore the evaluation may be carried out within these ranges of diameter, weight, and steel ball temperature.
The outer flame length means the length of the flame directly above the center of the burner opening.

By setting the steel ball sinking distance and melt diameter distance in the hot steel ball test of polyurethane foam made from the foamable urethane resin composition of the present invention within the specified ranges described above, the polyurethane foam can be made less susceptible to fire spread when exposed to a fire or other fire.

The polyurethane foam made from the foamable urethane resin composition of the present invention has a steel ball sinking distance of 10 mm or less in a hot steel ball test. If the steel ball sinking distance exceeds 10 mm, the polyurethane foam will be prone to fire spread if exposed to a fire, making it difficult to effectively prevent the spread of fire. From the perspective of effectively preventing the spread of fire, the steel ball sinking distance is preferably 5 mm or less, more preferably 3 mm or less, and even more preferably 0 mm.

The polyurethane foam made from the foamable urethane resin composition of the present invention preferably has a melt diameter distance of 15 mm or less in a hot steel ball test. A melt diameter distance of 15 mm or less makes the polyurethane foam less susceptible to fire spread when exposed to a fire, etc., and effectively prevents the spread of fire. From the perspective of effectively preventing the spread of fire, the melt diameter distance is preferably 14 mm or less, more preferably 13 mm or less, and even more preferably 12 mm or less. The melt diameter distance is 0 mm or more.

The steel ball sinking distance and melt diameter distance can be adjusted to the desired values by adjusting the type of polyol compound and water content contained in the foamable urethane resin composition.

In the hot steel ball evaluation, the steel ball sinks into the test specimen, forming a cavity from the top surface to the interior. The sinking distance of the steel ball refers to the maximum distance of the cavity perpendicular to the top surface of the test specimen (this does not include areas that discolor due to heat but retain their shape). The fusion diameter distance is the diameter of the hole formed by the heated steel ball on the top surface of the test specimen. Note that if the hole formed on the top surface of the test specimen is circular, the hole diameter refers to the diameter of that circle; if the hole is elliptical, it refers to the major axis. If the hole shape is other than circular or elliptical, the maximum distance between any two points on that shape is taken as the hole diameter. Note that if the test specimen does not melt and no cavity is formed on the top surface, the diameter of the carbonized or discolored area is measured in the same way.

The polyurethane foam used in the hot steel ball evaluation was prepared under the conditions described in the examples.

(Total heat generation)
It is preferable that a polyurethane foam made from the foamable urethane resin composition of the present invention has a total calorific value of 8 MJ/ ^m2 or less when heated for 5 minutes at a radiant heat intensity of 50 kW/ ^m2 in accordance with the ISO-5660 test method. When the total calorific value is 8 MJ/ ^m2 or less, the polyurethane foam made from the foamable urethane resin composition of the present invention has a predetermined flame retardancy. When the polyurethane foam has a predetermined flame retardancy and the steel ball sinking distance and fusion diameter distance are equal to or less than certain values as described above, the polyurethane foam has both flame retardancy and flame retardancy, and can more effectively prevent the spread of fire in the event of a fire.
From the viewpoint of further improving the flame retardancy of the polyurethane foam, the total calorific value is preferably 7.8 MJ/m ² or less, and more preferably 7.5 MJ/m ² or less.

(Maximum heat generation rate)
When a polyurethane foam made from the foamable urethane resin composition of the present invention is heated for 5 minutes at a radiant heat intensity of 50 kW/ ^m2 in accordance with the ISO-5660 test method, the maximum heat release rate is preferably 200 kW/m2 or less. When the maximum heat release rate is 200 kW/m2 ^{or less} , the polyurethane foam made from the foamable urethane resin composition of the present invention has a predetermined flame retardancy. Furthermore, by adjusting both the maximum heat release rate and the total heat release amount as described above, the flame retardancy is further improved.
By having a predetermined flame retardancy and, as described above, having the steel ball sinking distance and fusion diameter distance below certain values, the polyurethane foam has both flame retardancy and the property of not spreading fire, and can more effectively prevent the spread of fire in the event of a fire.
From the viewpoint of further improving the flame retardancy of the polyurethane foam, the maximum heat release rate is preferably 150 kW/m ² or less, and more preferably 130 kW/m ² or less.

The total calorific value and maximum heat release rate can be obtained by a cone calorimeter test, and specifically, can be measured by the method described in the Examples.
In the above-mentioned cone calorimeter test, it is preferable that the polyurethane foam used in the test has a shape stability to such an extent that it does not come into contact with the spark igniter of the cone calorimeter.

(Polyol Compound)
The polyol compound contained in the foamable urethane resin composition of the present invention includes a polyol containing resin microparticles. This makes it easier to prevent shrinkage of polyurethane foams made from the foamable urethane resin composition during use. It also makes it easier to suppress expansion in a cone calorie test, improving dimensional stability at high temperatures. While the reason for this is unclear, it is presumed that the use of a polyol containing resin microparticles increases the proportion of open cells in the foam. Furthermore, when the foam is observed with an SEM, holes that appear to have been destroyed by the microparticles can be confirmed.
The resin fine particles are not particularly limited, but are preferably polymers of at least one monomer selected from the group consisting of acrylonitrile, methacrylonitrile, fluorine-containing acrylonitrile, α-ethyl acrylonitrile, styrene, vinyl acetate, and acrylic monomers. Among these, polymers of at least one monomer selected from the group consisting of acrylonitrile, methacrylonitrile, styrene, and fluorine-containing acrylonitrile are preferred, and polymers of acrylonitrile are preferred.

Examples of acrylic monomers include (meth)acrylates, such as alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, and n-decyl (meth)acrylate. In addition to these, hydroxyl group-containing (meth)acrylates such as hydroxyalkyl (meth)acrylates can also be used. Furthermore, the acrylic monomers may be fluorine-containing monomers. Examples of fluorine-containing monomers include monomers such as the alkyl (meth)acrylates and hydroxyl group-containing (meth)acrylates, in which one or more hydrogen atoms constituting the monomer are substituted with fluorine atoms.
Either or both of acrylate and methacrylate will be collectively referred to as (meth)acrylate.

The content of the resin microparticles in the total polyol composition is preferably 0.01% by mass or more, more preferably 0.02% by mass or more. When the content of the resin microparticles is equal to or greater than these lower limits, shrinkage of the polyurethane foam is easily suppressed. The content of the resin microparticles in the total polyol composition is preferably 5% by mass or less, more preferably 1% by mass or less.
The foamable urethane resin composition of the present invention preferably comprises a polyol composition containing a polyol compound, a flame retardant that is liquid at room temperature, a blowing agent, and a catalyst, and a polyisocyanate compound, and is produced by mixing the polyol composition and the polyisocyanate compound.

The content of the resin microparticle-containing polyol, based on the total amount of polyol compounds, is preferably 3 to 40% by mass, more preferably 4 to 35% by mass, even more preferably 5 to 30% by mass, and even more preferably 8 to 30% by mass. If the content of the resin microparticle-containing polyol is above these lower limits, shrinkage of the polyurethane foam is more easily suppressed, while if it is below these upper limits, the flame-retardant properties of the polyurethane foam are more easily improved.

The type of polyol containing resin fine particles is not particularly limited, and for example, the polyols described below can be used. Among them, from the viewpoint of suppressing shrinkage of the polyurethane foam and obtaining appropriate reactivity, the polyol containing resin fine particles is preferably a polyether polyol containing resin fine particles, and more preferably an amine-based polyether polyol containing resin fine particles. As the amine-based polyether polyol, for example, the tolylene diamine-based polyether polyol (TDA-based polyether polyol) and Mannich-based polyether polyol described below are preferred.
From the same viewpoint, the hydroxyl value of the polyether polyol containing resin fine particles is preferably 250 to 550 mgKOH/g, more preferably 300 to 500 mgKOH/g.Furthermore, the number of functional groups (number of hydroxyl groups) of the polyether polyol containing resin fine particles is preferably 2 to 4.
The hydroxyl value is a value measured in accordance with JIS K1557-1:2007.

Polyols containing resin microparticles can be produced by known methods. Examples include a method in which a resin produced by bulk polymerization or solution polymerization is pulverized into microparticles, and the resulting fine resin powder is then added to a polyol and classified as needed; a method in which an emulsion containing resin microparticles obtained by emulsion polymerization is added as is; and a method in which a monomer is dissolved or dispersed in a polyol, a radical polymerization initiator such as AIBN or BPO is added, and the resulting mixture is heated to polymerize the monomers to form a polyol containing resin microparticles. Among these, the method of forming resin microparticles by polymerization in a polyol is most preferred, as it results in a stable polyol composition in which the particles are less likely to settle even when left for long periods of time.

The polyether polyols will be described below. These polyether polyols may be the polyether polyols in the resin microparticle-containing polyether polyols described above, or they may be polyether polyols that do not contain resin microparticles.

<Polyether polyol>
The polyether polyol is a polyoxyalkylene polyol obtained by ring-opening addition polymerization of an alkylene oxide to an initiator having two or more active hydrogen atoms. Specific examples of the initiator include aliphatic polyhydric alcohols (e.g., glycols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexylene glycol, and cyclohexanedimethanol; triols such as trimethylolpropane and glycerin; tetrafunctional alcohols such as pentaerythritol; sugars such as sucrose and sorbitol); aliphatic amines (e.g., alkylenediamines such as ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, and neopentyldiamine; alkanolamines such as monoethanolamine and diethanolamine); and aromatic amines (e.g., aniline, tolylenediamine, xylylenediamine, diphenylmethanediamine, and Mannich condensation products). These may be used alone or in combination of two or more.

As the polyether polyol, from the viewpoint of enhancing the flame retardancy of the polyurethane foam, amine-based polyether polyols such as tolylenediamine-based polyether polyols and Mannich-based polyether polyols, sucrose-based polyether polyols, and sorbitol-based polyether polyols are preferred.
The tolylenediamine-based polyether polyol is a polyether polyol obtained by using tolylenediamine as an initiator. The same applies to sucrose-based polyether polyols and sorbitol-based polyether polyols.
The Mannich polyether polyol is a polyether polyol obtained by utilizing the Mannich reaction, which is a Mannich condensation product having two or more hydroxyl groups in the molecule, or a polyether polyol obtained by adding an alkylene oxide to such a Mannich condensation product. More specifically, it is a Mannich condensation product obtained by the Mannich reaction of at least one of phenol and its alkyl-substituted derivatives, formaldehyde, and alkanolamine, or a polyether polyol obtained by ring-opening addition polymerization of this compound with at least one of ethylene oxide and propylene oxide.

The hydroxyl value of the polyether polyol is preferably 200 to 1,000 mgKOH/g, and more preferably 300 to 600 mgKOH/g. The hydroxyl value is measured in accordance with JIS K1557-1:2007.

<Polyester polyol>
The polyol compound contained in the foamable urethane resin composition of the present invention preferably contains a polyester polyol.
Examples of polyester polyols include aromatic polyester polyols and aliphatic polyester polyols. However, considering the flame retardancy of the resulting polyurethane foam, aromatic polyester polyols are preferred. The aromatic polyester polyol is preferably a condensate of an aromatic dicarboxylic acid, such as o-phthalic acid (phthalic acid), m-phthalic acid (isophthalic acid), p-phthalic acid (terephthalic acid), or naphthalenedicarboxylic acid, with a glycol. Among these, from the viewpoint of enhancing the flame retardancy of the polyurethane foam, reducing the values of the steel ball sinking distance and melt diameter distance described above, and improving the flame spread resistance, the polyol compound preferably contains a phthalic acid-based polyester polyol, which is a condensate of phthalic acid and a glycol, and more preferably contains a p-phthalic acid-based polyester polyol, which is a condensate of p-phthalic acid and a glycol.
The glycol is not particularly limited, but it is preferable to use low molecular weight aliphatic glycols known as constituent components of polyester polyols, such as ethylene glycol, propylene glycol, diethylene glycol, and triethylene glycol.

From the perspective of reducing the steel ball sinking distance and molten diameter distance values and improving fire spread prevention, the content of phthalate-based polyester polyol is preferably 60 to 97% by mass, and more preferably 65 to 95% by mass, based on the total amount of polyol components.

In the present invention, from the viewpoint of obtaining a polyurethane foam that is resistant to shrinkage and fire spread, the polyol compound contained in the foamable urethane resin composition preferably contains a polyol containing resin microparticles and a phthalic acid-based polyester polyol. Here, the weight ratio of the phthalic acid-based polyester polyol to the polyol containing resin microparticles (phthalic acid-based polyester polyol/polyol containing resin microparticles) is preferably 95/5 to 55/45, and more preferably 90/10 to 60/40.

The hydroxyl value of the polyester polyol is not particularly limited, but from the perspective of improving the flame-retardant properties of the polyurethane foam, it is preferably 100 to 400 mgKOH/g, and more preferably 150 to 350 mgKOH/g.

(Polyisocyanate compound)
The polyisocyanate compound contained in the foamable urethane resin composition of the present invention can be any of various polyisocyanate compounds, such as aromatic, alicyclic, and aliphatic polyisocyanate compounds having two or more isocyanate groups. Liquid diphenylmethane diisocyanate (MDI) is preferably used because of its ease of handling, rapid reaction, excellent physical properties of the resulting polyurethane foam, and low cost. Examples of liquid MDI include crude MDI (also known as polymeric MDI). Specific commercially available liquid MDI products include "44V-10" and "44V-20" (manufactured by Sumika Covestro Urethane Co., Ltd.) and "Millionate MR-200" (Nippon Polyurethane Industry Co., Ltd.). Uretonimine-containing MDI (e.g., 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 compounds known in the technical field of polyurethanes can be used without any limitations.

The isocyanate index of the foamable urethane resin composition of the present invention is preferably in the range of 150 to 700, more preferably 200 to 650, and even more preferably 250 to 600. When the isocyanate index is in this range, it becomes easier to adjust the steel ball sinking distance and fusion diameter distance in the above-mentioned hot steel ball evaluation to the desired ranges.
The isocyanate index (INDEX) is calculated by the following method.

INDEX = number of equivalents of isocyanate ÷ (number of equivalents of polyol + number of equivalents of water) × 100
where:
Equivalent weight of isocyanate = parts of polyisocyanate used x NCO content (%) x 100/NCO molecular weight Equivalent weight of polyol = OHV x parts of polyol used / molecular weight of KOH, where OHV is the hydroxyl value of the polyol (mg KOH/g).
Equivalent number of water = parts of water used × number of OH groups in water / molecular weight of water. In the above formula, the unit of parts used is weight (g), the molecular weight of the NCO group is 42, the NCO content is the proportion of NCO groups in the polyisocyanate compound expressed in mass %, and for the convenience of unit conversion in the above formula, the molecular weight of KOH is set to 56,100, the molecular weight of water is 18, and the number of OH groups in water is 2.

(liquid flame retardant)
The foamable urethane resin composition of the present invention contains a flame retardant that is liquid at room temperature. Here, room temperature means 23° C. The inclusion of a liquid flame retardant makes it easier to adjust the steel ball sinking distance and melt diameter distance described above to the desired range, and the liquid form of the flame retardant also makes it possible to suppress wear on the equipment and the like used when using the foamable urethane resin composition.
Examples of liquid flame retardants include phosphate ester flame retardants such as monophosphate esters and condensed phosphate esters.
The monophosphate ester is not particularly limited, but includes trimethyl phosphate, triethyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, tris(β-chloropropyl) phosphate, and the like.
The condensed phosphate ester is not particularly limited, but examples thereof include resorcinol polyphenyl phosphate (trade name: CR-733S), bisphenol A polycresyl phosphate (trade name: CR-741), and aromatic condensed phosphate ester (trade name: CR747).
The content of the liquid flame retardant is preferably 5 to 100 parts by mass, more preferably 10 to 80 parts by mass, and even more preferably 20 to 70 parts by mass, per 100 parts by mass of the polyol compound.

(Foam stabilizer)
The foamable urethane resin composition of the present invention optionally contains a foam stabilizer. Examples of foam stabilizers include surfactants such as polyoxyalkylene foam stabilizers (e.g., polyoxyalkylene alkyl ethers) and silicone foam stabilizers (e.g., organopolysiloxanes). However, any surfactant having a structure containing polar and non-polar moieties in the molecule can provide a surfactant effect, so the type of foam stabilizer is not limited to the above. Furthermore, the silicone foam stabilizer may also contain a graft copolymer of polydimethylsiloxane and polyethylene glycol.
The content of the foam stabilizer is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 8 parts by mass, and even more preferably 0.5 to 5 parts by mass, relative to 100 parts by mass of the polyol compound. One type of foam stabilizer may be used alone, or two or more types may be used.

(Blowing agent)
The foamable urethane resin composition of the present invention contains a foaming agent. Specific examples of the foaming agent include water, low-boiling hydrocarbons, chlorinated aliphatic hydrocarbon compounds, fluorine compounds, hydrochlorofluorocarbon compounds, hydrofluorocarbons, ether compounds, and hydrofluoroolefins. Further examples of the foaming agent include organic physical foaming agents such as mixtures of these compounds, and inorganic physical foaming agents such as nitrogen gas, oxygen gas, argon gas, and carbon dioxide gas.
Examples of the low boiling point hydrocarbon include propane, butane, pentane, hexane, heptane, cyclopropane, cyclobutane, cyclopentane, cyclohexane, and cycloheptane.
Examples of the chlorinated aliphatic hydrocarbon compounds include dichloroethane, propyl chloride, isopropyl chloride, butyl chloride, isobutyl chloride, pentyl chloride, and isopentyl chloride.
Examples of the fluorine compound include CHF ₃ , CH ₂ F ₂ , and CH ₃ F.
Examples of the hydrochlorofluorocarbon compounds include trichloromonofluoromethane, trichlorotrifluoroethane, and dichloromonofluoroethane (for example, HCFC141b (1,1-dichloro-1-fluoroethane), HCFC22 (chlorodifluoromethane), and HCFC142b (1-chloro-1,1-difluoroethane)).
Examples of the hydrofluorocarbon include HFC-245fa (1,1,1,3,3-pentafluoropropane) and HFC-365mfc (1,1,1,3,3-pentafluorobutane).
Examples of the ether compounds include diisopropyl ether.
Examples of the hydrofluoroolefin include HFO-1233zd(E) (trans-1-chloro-3,3,3-trifluoropropene), HFO-1234yf (2,3,3,3-tetrafluoro-1-propene), and HFO-1336mzz(Z) (cis-1,1,1,4,4,4-hexafluorobut-2-ene).

In the present invention, the blowing agent preferably contains water. More specifically, a blowing agent containing water in combination with at least one compound selected from the group consisting of low-boiling hydrocarbons, chlorinated aliphatic hydrocarbon compounds, fluorine compounds, hydrochlorofluorocarbon compounds, hydrofluorocarbons, ether compounds, and hydrofluoroolefins is preferred. Examples of water that can be used include ion-exchanged water and distilled water. The amount of water per 100 parts by mass of polyol compound is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and preferably 2.0 parts by mass or less, more preferably 1.5 parts by mass or less, and even more preferably 1.1 parts by mass or less. When the water content is above these lower limits, the foamable urethane resin composition is more easily foamed, and the density can be more easily adjusted to the desired range. When the water content is below these upper limits, the steel ball sinking distance and melt diameter distance in a hot steel ball test of the polyurethane foam can be more easily adjusted to the desired range.

In the present invention, the blowing agent preferably contains a hydrofluoroolefin, and more preferably contains both the hydrofluoroolefin and the above-mentioned water. The amount of hydrofluoroolefin per 100 parts by mass of the polyol compound is preferably 10 to 60 parts by mass, more preferably 15 to 50 parts by mass, and even more preferably 25 to 45 parts by mass.

(catalyst)
The foamable urethane resin composition of the present invention contains a catalyst. The catalyst may contain, for example, one or both of a urethanization catalyst and a trimerization catalyst, and preferably contains both. Note that the catalyst contained in the foamable urethane resin composition does not fall under the category of inorganic filler in the present invention.

The urethanization catalyst is a catalyst that accelerates the reaction between the polyol component and the polyisocyanate. Specific examples 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 tin compounds include stannous octoate, dibutyltin diacetate, dibutyltin dilaurate, etc. Examples of bismuth compounds 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 urethanization catalyst may be used alone or in combination of two or more.

There are no particular limitations on the amount of urethane catalyst used in the foamable urethane resin composition, but it is preferably in the range of 0.3 to 10 parts by mass, more preferably 0.5 to 8 parts by mass, and even more preferably 1 to 5 parts by mass, per 100 parts by mass of urethane resin. By keeping the amount within the above range, the reaction between the polyol compound and the polyisocyanate compound can be promoted at an appropriate reaction rate. Note that 100 parts by mass of urethane resin refers to a total of 100 parts by mass of the polyol compound and the polyisocyanate compound.

A trimerization catalyst is a catalyst that promotes trimerization to form isocyanurate bonds. By promoting trimerization of polyurethane resin, the flame retardancy of polyurethane foam is improved.
Examples of trimerization catalysts 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 salt, triethylammonium salt, and triphenylammonium salt; and quaternary ammonium salts such as tetramethylammonium salt, tetraethylammonium, and tetraphenylammonium salt.
The trimerization catalyst may be used alone or in combination of two or more.

The amount of the trimerization catalyst is not particularly limited, but is preferably in the range of 0.3 to 10 parts by mass, more preferably 0.5 to 8 parts by mass, and even more preferably 0.8 to 5 parts by mass, per 100 parts by mass of the urethane resin. By adjusting the amount of the trimerization catalyst within the above range, an appropriate amount of isocyanurate bonds is formed, improving flame retardancy.
Furthermore, from the viewpoint of improving the curing speed and flame retardancy of the urethane, the total amount of catalyst is preferably 0.5 to 20 parts by mass, more preferably 1 to 16 parts by mass, and even more preferably 2 to 10 parts by mass, per 100 parts by mass of the urethane resin.

Note that these trimerization catalysts and urethanization catalysts do not fall under the category of inorganic fillers described below in this invention.

The foamable urethane resin composition may contain additives such as phenolic, amine, or sulfur-based antioxidants, heat and light stabilizers, metal inhibitors, antistatic agents, crosslinking agents, lubricants, softeners, pigments, and tackifying resins, as long as the effects of the present invention are not impaired.

(inorganic filler)
The foamable urethane resin composition of the present invention preferably contains substantially no inorganic filler. By containing substantially no inorganic filler, it is possible to provide a foamable urethane resin composition that is less likely to produce precipitates during storage, has excellent handleability, and can suppress wear on tools and the like used during use.
Here, "substantially free of inorganic filler" means that the content of inorganic filler is 5% by mass or less, preferably 1% by mass or less, based on the total amount of the foamable urethane resin composition.

The inorganic filler is an inorganic compound such as a particulate or fibrous compound, and examples thereof include metals, metal oxides, metal hydroxides, and ceramics. Examples of the inorganic filler include solid flame retardants and inorganic fillers other than solid flame retardants.
The solid flame retardant is a flame retardant that is solid at 23°C, and examples thereof include antimony-containing flame retardants such as antimony oxide, antimonate, and pyroantimonate; metal hydroxide-based flame retardants such as magnesium hydroxide, calcium hydroxide, and aluminum hydroxide; boron-containing flame retardants such as lithium borate and sodium borate; phosphinic acid-based flame retardants, phosphate-containing flame retardants, bromine-containing flame retardants, and red phosphorus.
In addition, examples of inorganic fillers other than solid flame retardants 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, barium carbonate, dawsonite, hydrotalcite, calcium sulfate, barium sulfate, gypsum fiber, potassium salts of calcium silicate, talc, clay, mica, montmorillonite, bentonite, activated clay, sepiolite, imogolite, sericite, glass fiber, glass beads, silica palan, aluminum nitride, boron nitride, silicon nitride, carbon black, graphite, carbon fiber, carbon palan, charcoal powder, various metal powders, potassium titanate, magnesium sulfate, lead zirconate titanate, aluminum borate, molybdenum sulfide, silicon carbide, stainless steel fiber, various magnetic powders, slag fiber, fly ash, silica alumina fiber, alumina fiber, silica fiber, zirconia fiber, and the like.

The foamable urethane resin composition of the present invention cures through a reaction between the polyol compound and the polyisocyanate compound, and its viscosity changes over time. Therefore, before using the foamable urethane resin composition, the foamable urethane resin composition is divided into two or more portions to prevent the foamable urethane resin composition from curing through reaction. Then, when using the foamable urethane resin composition, it is preferable to combine the two or more portions of the foamable urethane resin composition into one.

When dividing a foamable urethane resin composition into two or more components, each component should be divided so that curing does not begin on its own, but rather the curing reaction begins after the components of the foamable urethane resin composition are mixed together. Typically, a foamable urethane resin composition is divided into a polyol composition containing a polyol compound and a polyisocyanate composition containing a polyisocyanate compound.

The above-mentioned flame retardants, blowing agents, catalysts, and foam stabilizers that are liquid at room temperature, which are blended as needed, may be contained in the polyol composition, the polyisocyanate composition, or may be provided separately from the polyol composition and the polyisocyanate composition, but are preferably contained in the polyol composition.

The method for producing the foamable urethane resin composition is not particularly limited, but examples include a method in which a polyol composition and a polyisocyanate composition are pre-mixed and then mixed, or a method in which the components that make up the foamable urethane resin composition are kneaded together. However, the foamable urethane resin composition is typically produced by mixing the polyol composition and the polyisocyanate composition. The components can be mixed using known methods, such as a high-pressure foaming machine, a low-pressure foaming machine, a spray foaming machine, or a hand mixer.

(Viscosity of Polyol Composition)
The viscosity of the polyol composition at 20°C is not particularly limited, but is preferably 2,000 mPa·s or less, and more preferably 1,000 mPa·s or less. By setting the viscosity of the polyol liquid to the above upper limit or less, the fluidity of the foamable urethane resin composition is improved, and mixing defects can be suppressed. The viscosity of the polyol composition can be appropriately adjusted, for example, by the molecular weight of the polyol compound used. The viscosity of the polyol composition was measured using a B-type viscometer at a temperature of 20°C.

(Application)
The uses of the foamable urethane resin composition of the present invention are not particularly limited, and it can be used to fill cavities in structures such as buildings, furniture, automobiles, trains, ships, etc., or to spray onto such structures. Among these, it is preferable to use it for spraying onto structures, i.e., as a foamable urethane resin composition for spraying.
Spraying can be carried out using a spraying device (e.g., A-25 manufactured by GRACO) and a spray gun (e.g., D-gun manufactured by Gasmar). A typical spraying device and spray gun sprays the isocyanate and polyol in the foaming solution at an equal volume ratio, so the foaming solution can be reacted at a volume ratio of 1.0 isocyanate to 0.8 to 1.2 polyol. Spraying can be carried out by adjusting the temperature of a polyol composition and a polyisocyanate composition contained in separate containers in the spraying device, causing them to collide and mix at the tip of the spray gun, and turning the mixed liquid into a mist using air pressure. Spraying devices and spray guns are known, and commercially available products can be used.

[Polyurethane foam]
The polyurethane foam of the present invention is formed from the above-described foamable urethane resin composition, and specifically, is obtained by foaming and curing the foamable urethane resin composition.
The polyurethane foam has a steel ball sinking distance of 10 mm or less in a hot steel ball evaluation. If the steel ball sinking distance exceeds 10 mm, the polyurethane foam is prone to fire spread when exposed to a fire, making it difficult to effectively prevent the spread of fire. From the viewpoint of effectively preventing the spread of fire, the steel ball sinking distance is preferably 5 mm or less, more preferably 3 mm or less, even more preferably 2 mm or less, and still more preferably 0 mm. The steel ball sinking distance is 0 mm or more. The method for evaluating the steel ball sinking distance is as described above.

The polyurethane foam preferably has a melt diameter distance of 15 mm or less in a hot steel ball test. If the melt diameter distance exceeds 15 mm, the polyurethane foam will be prone to fire spread if exposed to a fire, making it difficult to effectively prevent the spread of fire. From the perspective of effectively preventing the spread of fire, the melt diameter distance is preferably 14 mm or less, more preferably 13 mm or less, and even more preferably 12 mm or less. The melt diameter distance is 0 mm or more.

Fires caused by polyurethane foam are largely due to sparks and fireballs (lumps of iron heated to high temperatures) during welding and cutting. According to the inventors' findings, when a fireball comes into contact with polyurethane foam, it melts the resin as it progresses inside, posing a risk of ignition and fire spreading from within the polyurethane foam. The hot steel ball evaluation described above reproduces and evaluates fires caused by polyurethane foam during welding and cutting, and can be used to evaluate whether a polyurethane foam is resistant to the spread of fire.

The density of the polyurethane foam is not particularly limited, but is preferably in the range of 20 to 200 kg/ ^m3 . By setting the density to 200 kg/m3 ^or less, the polyurethane foam becomes lightweight and its application to structures becomes easier. Furthermore, by setting the density to 20 kg/m3 or ^more , the desired flame retardancy is more likely to be exhibited. 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 25 to 80 kg/ ^m3 . The density of the polyurethane foam can be measured in accordance with JIS K7222.

The present invention will be explained in more detail using examples, but the present invention is not limited to these examples in any way.

Details of each component used in each example and comparative example are as follows.
(1) Polyol Compound (i) Resin Fine Particle-Containing Polyether Polyol/Resin Fine Particle-Containing PPG1 (Hydroxyl Value = 315 mg KOH/g) The resin fine particles are acrylonitrile polymers, the type of polyether polyol is Mannich polyether polyol, and the fine particles are 0.5 to 1.2 wt%
PPG2 containing resin particles (hydroxyl value = 385 mg KOH/g) The resin particles are acrylonitrile polymer, the type of polyether polyol is TDA-based polyether polyol, and the particles are 0.5 to 1.2 wt%
The resin particle content in resin particle-containing PPG1 and PPG2 was 0.5 to 1.2 wt % as described above, but is shown in Table 1 as 1.0 wt %.
(ii) Polyether polyol/sucrose-based polyether polyol containing no resin fine particles (manufactured by Mitsui Chemicals, Inc., product name: GR84, hydroxyl value = 450 mg KOH/g)
Sorbitol-based polyether polyol (manufactured by Mitsui Chemicals, Inc., product name: Actocol SOR400, hydroxyl value = 400 mg KOH/g)
Ethylenediamine-based polyether polyol (manufactured by AGC Inc., product name: Exenol 750ED, hydroxyl value = 760 mg KOH/g)
(iii) Polyester polyol: p-phthalic acid-based polyester polyol (manufactured by Kawasaki Chemical Industries, Ltd., product name: RFK-505, hydroxyl value = 250 mg KOH/g)
(2) Liquid flame retardant: Phosphate ester flame retardant (tris(β-chloropropyl)phosphate), (manufactured by Daihachi Chemical Industry Co., Ltd., product name: TMCPP)
(3) Foam stabilizer: Silicone foam stabilizer (manufactured by Toray Dow Corning Co., Ltd., product name: SH-193)
(4) Catalyst (i) Trimerization catalyst/quaternary ammonium salt (manufactured by Evonik Japan, product name: TMR-7)
(ii) Urethane catalyst/imidazole compound (Kao Corporation, product name: KL No. 390)
Bismuth compound (manufactured by Nitto Kasei Co., Ltd., product name: Neostan U-600)
(5) Blowing agent: Water; HFO-1233zd (hydrofluoroolefin) (manufactured by Honeywell, product name: Solstice LBA)
(6) Polyisocyanate compound/MDI (manufactured by Sumika Covestro Urethane Co., Ltd., product name: 44V-20)

The measurement methods for each physical property and characteristic are as follows:

[Hot steel ball evaluation]
For the polyurethane foams produced in each of the Examples and Comparative Examples, the sinking distance and melting diameter distance of the steel ball were measured according to the following procedures (1) to (3).
(1) The polyurethane foam was cut into a cube with sides of 50 mm to prepare a test specimen.
(2) A wire mesh was placed 30 mm from the burner port of a Bunsen burner (outer flame length 70 mm), and a steel ball (SUS304) with a diameter of 10.0 mm and a weight of 4.15 g was placed on the wire mesh and heated for 7 minutes until the entire steel ball turned red, bringing the steel ball temperature to 630°C. The steel ball temperature was measured by moving the heated steel ball from the wire mesh to another table that would not affect the radiation temperature measurement. The steel ball temperature was measured using a radiation thermometer (Keyence: FT-H40K) with the radiation coefficient of the steel ball used set to 0.45, and the value displayed on the radiation thermometer divided by 0.45 was used as the evaluation temperature (630°C). Note that new steel balls were used.
(3) In an atmosphere of 23°C, the steel ball heated in (2) above was immediately placed on the center of the upper part of the test piece of (1) above and left to stand until the steel ball had completely sunk in. Next, the test piece was left to stand at 23°C for 30 minutes and then sufficiently cooled, and the cross section of the test piece was cut out to measure the sinking distance of the steel ball and the fusion diameter distance.
The resulting sinking distance and molten diameter distance of the steel ball were used to judge the quality of the flame-resistance property as follows:

<Hot steel ball evaluation criteria>
○: The sinking distance of the steel ball is 5 mm or less, and the fusion diameter distance is 15 mm or less. △: The sinking distance of the steel ball is 5 mm or less, and the fusion diameter distance is more than 15 mm. ×: Anything other than the above "○" and "△".

[Maximum heat release rate, total heat release]
The maximum heat release rate and total heat release value of the polyurethane foams produced in each Example and Comparative Example were evaluated using the following method. A polyisocyanate compound (200 g total, 10°C liquid temperature) and a mixture prepared by mixing a polyol compound, liquid flame retardant, foam stabilizer, catalyst, and blowing agent according to the formulation shown in Table 1 were placed in a polypropylene beaker and stirred for 3 seconds with a laboratory spar. The mixture was then immediately spread on a 12.5 mm thick gypsum board to obtain a polyurethane foam. The polyurethane foam adhered to the gypsum board as a base was cut into a length of 10 cm, width of 10 cm, and thickness of 3.25 cm (including 12.5 mm gypsum board) to prepare a cone calorimeter test sample. A cone calorimeter test was performed as follows. The test sample was heated for 5 minutes at a radiant heat intensity of 50 kW/ ^m² , and the maximum heat release rate and total heat release value were measured in accordance with the ISO-5660 test method. In addition to the above-mentioned method, the polyurethane foam was also prepared by spraying the foamable urethane resin composition onto a structure using a spraying device and a spray gun, with similar values being obtained.

[Evaluation of shrinkage]
The polyurethane foams obtained in each of the Examples and Comparative Examples were processed into a size of 10 cm in length, 10 cm in width and 7 cm in thickness, and stored at 40° C. and 95% RH for 3 days.
The length retention rate for each of the length and width was calculated using the following formula, and the average of these was used to determine the shape retention rate. A shape retention rate of 100% means that there was no shrinkage at all.
Retention rate = 100 x (length of one side after storage for 3 days) / (length of one side before storage).
〇: Shape retention rate is 95% or more but less than 100% ×: Less than 95%

[Example 1]
According to the formulations in Table 1, a polyol compound, liquid flame retardant, foam stabilizer, catalyst, and blowing agent were weighed into a 1000 mL polypropylene beaker and stirred at 20°C for 10 seconds with a hand mixer to prepare a polyol composition. The polyol composition was then cooled to 10°C, and a polyisocyanate composition (polyisocyanate compound) also kept at 10°C was added to prepare a foamable urethane resin composition. The composition was stirred for 3 seconds with a laboratory spar to prepare a polyurethane foam. The polyurethane foam was subjected to the hot steel ball evaluation described above. The maximum heat release rate, total heat release, and shape retention were also evaluated using the procedures described above. The results of the various evaluations are shown in Table 1.

[Examples 2 to 5, Comparative Examples 1 to 5]
A polyurethane foam was obtained in the same manner as in Example 1, except that the formulation was changed as shown in Table 1. The polyurethane foam was subjected to the hot steel ball evaluation described above. The maximum heat release rate, total heat release amount, and shape retention were also evaluated using the same procedures as above. The results of the various evaluations are shown in Table 1.

As shown in each example, polyurethane foams formed from the foamable urethane resin composition of the present invention have a short steel ball sinking distance and a short melt diameter distance, demonstrating their flame-spread resistance. Furthermore, polyurethane foams formed from the foamable urethane resin composition of the present invention are also resistant to shrinkage. In other words, polyurethane foams having both flame-spread resistance and shrinkage resistance were obtained.
In contrast, the polyurethane foam formed from the foamable urethane resin composition of the comparative example did not contain the resin fine particle-containing polyether polyol and was found to be prone to shrinkage.

Claims (9)

A foamable urethane resin composition comprising a polyol compound, a polyisocyanate compound, a flame retardant that is liquid at room temperature, a foaming agent, and a catalyst,
The polyol compound includes a polyol containing resin fine particles,
the polyol compound contains a phthalic acid-based polyester polyol, and the content of the phthalic acid-based polyester polyol is 80 to 95 mass% based on the total amount of the polyol components;
the blowing agent comprises a hydrofluoroolefin and water;
an isocyanate index of 250 to 700;
A foamable urethane resin composition, wherein a steel ball sinks a distance of 10 mm or less in the hot steel ball test described below on a polyurethane foam made from the foamable urethane resin composition.
(Hot steel ball evaluation)
(1) The polyurethane foam is cut into a cube with sides of 50 mm to be used as a test specimen.
(2) A wire mesh is placed 30 mm from the burner port of a Bunsen burner (outer flame length 70 mm), and a steel ball with a diameter of 10.0 mm and a weight of 4.15 g is placed on the wire mesh. The steel ball is heated for at least 5 minutes or more until the entire steel ball turns red, and the temperature of the steel ball reaches 630°C.
(3) In an atmosphere of 23°C, the steel ball heated in (2) above is immediately placed on the center of the upper part of the test piece in (1) above and left to stand until the steel ball has completely sunk in. Next, the cross section of the sufficiently cooled test piece is cut and the sinking distance and fusion diameter distance of the steel ball are measured. 2. The foamable urethane resin composition according to claim 1, wherein a polyurethane foam made from the foamable urethane resin composition has a total calorific value of 8 MJ/ ^m2 or less when heated for 5 minutes at a radiant heat intensity of 50 kW/m2 in ^accordance with the ISO-5660 testing method. 3. The foamable urethane resin composition according to claim ¹ , wherein a polyurethane foam made from the foamable urethane resin composition has a maximum heat release rate of 200 kW/m2 ^{or less} when heated for 5 minutes at a radiant heat intensity of 50 kW/m2 in accordance with the ISO-5660 test method. The foamable urethane resin composition according to any one of claims 1 to 3, wherein the resin microparticle-containing polyol is an amine-based polyether polyol containing resin microparticles. The foamable urethane resin composition according to any one of claims 1 to 4, wherein the resin microparticles are a polymer of at least one monomer selected from the group consisting of acrylonitrile, methacrylonitrile, fluorinated acrylonitrile, α-ethyl acrylonitrile, styrene, vinyl acetate, and acrylic monomers. The foamable urethane resin composition includes a polyol composition containing a polyol compound, a flame retardant that is liquid at room temperature, a foaming agent, and a catalyst, and a polyisocyanate compound;
6. The foamable urethane resin composition according to claim 1, wherein the content of the resin fine particles is 0.01 mass% or more based on the total amount of the polyol composition. 7. The foamable urethane resin composition according to claim 1, wherein the content of the water is 1.5 parts by mass or less per 100 parts by mass of the polyol compound. The foamable urethane resin composition according to any one of claims 1 to 7 , wherein the catalyst contains a trimerization catalyst. The foamable urethane resin composition according to any one of claims 1 to 8 , wherein the content of the inorganic filler is 5% by mass or less.