Phenolic resin foam, pyrolytic treatment method for phenolic resin foam, pyrolytic product for phenolic resin foam, and method for producing phenolic resin foam

Abstract

When the phenolic resin foam is subjected to pyrolysis gas chromatography-mass spectrometry under heating conditions of 600 DEG C, [A] / [B] is 2.0-15 (inclusive), where [A] is the area value of the signal of structural formula (A) and [B] is the area value of the signal of structural formula (B). (A) (B)

Description

[0001] Cross-reference of related applications

[0002] This application claims the benefit of Japanese Patent Application No. 2023-075264, filed in Japan on April 28, 2023, and the entire disclosure of that prior application is incorporated herein by reference. Technical Field

[0003] The present invention relates to a phenolic resin foam, a method for thermal decomposition treatment of a phenolic resin foam, a thermally decomposed product of a phenolic resin foam, and a method for producing a phenolic resin foam. Background Art

[0004] Phenolic resin foams, even among foamed plastic insulation materials, possess high thermal insulation, flame retardancy, and heat resistance, making them widely used as building materials and general industrial materials. However, unlike thermoplastic resins, phenolic resins form a cross-linked structure upon solidification, which prevents them from softening and / or melting due to heat and makes them difficult to dissolve in solvents. Therefore, regenerating phenolic resin solids into plastic raw materials is technically difficult.

[0005] Therefore, phenolic resin foams contained in industrial waste and / or general waste are disposed of by incineration or landfill. However, due to concerns about environmental load, there is a strong demand for a technology that allows for recycling rather than disposal as waste.

[0006] A technique for dissolving a thermosetting resin for the purpose of recycling is reported in Patent Document 1. Patent Document 1 discloses a technique for obtaining a low-molecular-weight component by heating a thermosetting resin cured in a non-foamed state in a subcritical solvent.

[0007] Patent Document 2 discloses a technique in which phenolic resin foam powder is crushed into granules (powder), extruded in the presence of phenols, and the extruded product is used as a raw material for a phenolic resin foam.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 2001-151933

[0011] Patent Document 2: Japanese Patent Application Laid-Open No. 2003-183475 Summary of the Invention

[0012] Problems to be solved by the invention

[0013] However, in Patent Document 1, the thermosetting resin cured in a non-foamed state is pre-crushed and then decomposed. However, there are problems such as the presence of by-products and / or solid residues after the decomposition treatment. Therefore, when the decomposition product is directly used as a raw material for the resin foam, a good foam cannot be obtained. In addition, the load on the manufacturing equipment is large, and there is a possibility that the foam cannot be produced.

[0014] In Patent Document 2, the phenolic resin foam is decomposed in a short time using an extruder. However, insufficient decomposition or formation of carbonized products may result in a decrease in the performance of the phenolic resin foam.

[0015] That is, a so-called chemical recycling technology is required that can completely decompose a phenolic resin foam and use it as a raw material for a phenolic resin foam without performing particularly complicated treatments.

[0016] An object of the present invention is to provide a phenolic resin foam having excellent properties, which is obtained by chemically decomposing a phenolic resin foam and recycling the recovered product as a part of a resin raw material.

[0017] Solutions for solving problems [1]

[0019] A phenolic resin foam, wherein, when the phenolic resin foam is subjected to pyrolysis gas chromatography-mass spectrometry analysis under heating conditions of 600° C., when the area value of the signal of structural formula (A) is defined as [A] and the area value of the signal of structural formula (B) is defined as [B], [A] / [B] is 2.0 or more and 15 or less,

[0020] (A)

[0021] (B) [2]

[0023] The phenolic resin foam according to [1], wherein the thermal conductivity is 0.016 W / (m·K) or more and 0.026 W / (m·K) or less. [3]

[0025] The phenolic resin foam according to [1] or [2] has a closed cell ratio of 85% or more. [4]

[0027] The phenolic resin foam according to any one of [1] to [3], having a density of 20 kg / m 3 Above and 70kg / m 3 the following. [5]

[0029] A method for thermal decomposition treatment of a phenolic resin foam, characterized in that the phenolic resin foam is heated and pressurized in a mononuclear phenol compound or in a solution of water and a mononuclear phenol compound under conditions of 260° C. to 370° C., 1.5 MPa to 20 MPa, and 60 minutes to 240 minutes, thereby obtaining a decomposed product with a decomposition rate of 95% or more. [6]

[0031] A decomposition product obtained by thermally decomposing a phenolic resin foam, the decomposition product containing 0.01% to 4.0% of xanthene. [7]

[0033] The method for producing a phenolic resin foam according to any one of [1] to [4], wherein 0.1 parts by mass or more and 20.0 parts by mass or less of the decomposition product according to [6] are added to 100 parts by mass of the phenolic resin, and the foamed product is foamed and cured.

[0034] Effects of the Invention

[0035] According to the method of the present invention, a good phenolic resin foam can be obtained while containing xanthene. Furthermore, the decomposition product containing xanthene, a by-product obtained by decomposing the phenolic resin foam as a raw material, can be reused as part of the raw material for newly produced phenolic resin foam. DETAILED DESCRIPTION

[0036] The present invention relates to a phenolic resin foam containing a specified amount of xanthene. Furthermore, the present invention has discovered that by chemically decomposing the phenolic resin foam under specific conditions to render it solubilized, and reusing the resulting solubilized component as part of the raw material for newly produced phenolic resin foam, a phenolic resin foam with excellent performance comparable to existing products can be obtained.

[0037] Hereinafter, an embodiment of the present invention (hereinafter referred to as "this embodiment") will be described in detail. It should be noted that the present invention is not limited to the following embodiment, and can be implemented with various modifications within the scope of the gist thereof.

[0038] The pyrolysis gas chromatography-mass spectrometry analysis, density, thermal conductivity, and closed cell ratio of the phenolic resin foam obtained in this embodiment were determined by the methods described in the Examples.

[0039] In this specification, a phenolic resin foam obtained by subjecting it to a decomposition treatment (described later) is referred to as a "decomposition product." Furthermore, a phenolic resin obtained by adding a surfactant and the decomposition product to a phenolic resin is referred to as a "phenolic resin composition." A phenolic resin composition obtained by adding a foaming agent, a foaming nucleating agent, an acidic curing agent, etc. to impart foamability, or both foamability and curability, is referred to as a "foamable phenolic resin composition." A foam obtained by foaming and curing a phenolic resin composition is referred to as a "phenolic resin foam."

[0040] It is known that even if xanthenes are not present in conventional phenolic resin foams, xanthenes are generally produced during the heating process described later in pyrolysis gas chromatography-mass spectrometry analysis. The present invention has discovered that phenolic resin foams obtained by heating and pressurizing a phenolic resin foam in a predetermined solution under high temperature and high pressure conditions, and then reusing the decomposed product as part of the raw material for the phenolic resin foam, contain xanthenes in the decomposed product, resulting in a higher content of xanthenes than conventional phenolic resin foams. Pyrolysis gas chromatography-mass spectrometry analysis can be used as a method for measuring xanthenes in phenolic resin foams.

[0041] In a chromatogram obtained by thermal decomposition gas chromatography-mass spectrometry analysis of the phenolic resin foam obtained by the present invention under heating conditions at 600°C, the ratio [[A] / [B]] of the area value [A] of the signal of xanthene (A) to the area value [B] of the signal derived from the diphenylmethane derivative component (B) generated and detected by decomposition of the phenolic resin foam is 2.0 or more and 15 or less, preferably 2.2 or more and 13 or less, and more preferably 2.4 or more and 10 or less. If [[A] / [B]] is less than 2.0, the amount of raw materials subjected to thermal decomposition treatment is small, and thus the significance of recycling the phenolic resin foam is reduced. If it is greater than 15, the closed cell ratio of the obtained phenolic resin foam is reduced.

[0042] (A)

[0043] (B)

[0044] The density of the phenolic resin foam obtained by the present invention is 20 kg / m 3 Above and 70kg / m 3 Below, preferably 25kg / m 3 Above and 60kg / m 3 When the density of the phenolic resin foam is 20kg / m 3 When the density of the phenolic resin foam is 70 kg / m 3When the temperature is below 400 °C, the heat transfer of the phenolic resin portion of the phenolic resin foam is less likely to increase, thereby maintaining thermal insulation performance. It should be noted that the density of the phenolic resin foam can be adjusted to a desired value mainly by changing the following conditions: the proportion of the blowing agent, the temperature of the foamable phenolic resin composition, the timing of pre-forming in the process of spraying the mixed foamable phenolic resin composition onto the lower surface material, the ratio of the amount of the blowing agent added to the amount of the organic acid added as the acidic curing agent, and curing conditions such as temperature and / or residence time.

[0045] The thickness of the phenolic resin foam obtained by the present invention is not particularly limited and can be appropriately set. The thickness of the phenolic resin foam is preferably 30 mm or more and 200 mm or less. The thickness is more preferably 35 mm or more and 200 mm or less, and further preferably 40 mm or more and 200 mm or less.

[0046] The closed cell ratio of the phenolic resin foam obtained by the present invention is preferably 85% or greater, more preferably 90% or greater. Alternatively, the closed cell ratio may be, for example, 99% or less, 98% or less, or 97% or less. Since the closed cell ratio serves as an indicator of thermal insulation performance, a closed cell ratio of 85% or greater is preferred, as it provides excellent thermal insulation performance.

[0047] The closed cell ratio can be adjusted to a desired value mainly by adjusting the ratio of the component (A) in the foam and / or the reactivity of the phenolic resin and / or the temperature, and further changing the curing temperature conditions.

[0048] The thermal conductivity of the phenolic resin foam obtained by the present invention is 0.026 W / (m·K) or less, preferably 0.016 W / (m·K) or more and 0.025 W / (m·K) or less, more preferably 0.016 W / (m·K) or more and 0.024 W / (m·K) or less, and even more preferably 0.016 W / (m·K) or more and 0.023 W / (m·K).

[0049] The shape of the phenolic resin foam obtained by the present invention is not particularly limited and can be any shape. Examples of the shape of the phenolic resin foam include a cuboid (e.g., plate-like, layered, sheet-like, etc.), a polyhedron other than a cuboid (e.g., a regular tetrahedron, a regular octahedron, a regular dodecahedron, a regular icosahedron, etc.), a sphere, a pyramid, a cone, a torus, a hollow cylinder, a solid cylinder (cylinder), an irregular shape, etc. In one embodiment, the phenolic resin foam is a cuboid.

[0050] As the phenolic resin, a resol-type phenolic resin synthesized from an alkali metal hydroxide or an alkaline earth metal hydroxide is used.

[0051] The initial molar ratio of phenols to aldehydes in synthesizing the phenolic resin is preferably in the range of 1:1 to 1:4.5, more preferably in the range of 1:1.5 to 1:2.5.

[0052] Here, in the present embodiment, the phenols preferably used in the synthesis of the phenolic resin are phenol itself and other phenols. Examples of other phenols include resorcinol, catechol, o-cresol, m-cresol, p-cresol, xylenols, ethylphenols, p-tert-butylphenol, etc. In addition, binuclear phenols can also be used.

[0053] In addition, the aldehydes may be any compounds that can serve as aldehyde sources, and formaldehyde itself, other aldehydes, and / or their derivatives are preferably used as aldehydes. Examples of other aldehydes include glyoxal, acetaldehyde, chloroacetaldehyde, furfural, and benzaldehyde.

[0054] Resol-type phenolic resins are synthesized using phenols and aldehydes as raw materials by heating at a temperature range of 40-100°C with an alkaline catalyst. Furthermore, additives such as urea, dicyandiamide, and / or melamine may be added during or after the synthesis of the resol-type phenolic resin, as needed. When adding these additives, it is more preferable to mix urea, which has been previously methylolated with an alkaline catalyst, into the resol-type phenolic resin. Since the synthesized resol-type phenolic resin typically contains excess water, the water content is adjusted to an appropriate level during foaming.

[0055] In addition, surfactants may be added to the phenolic resin as additives. In addition, aliphatic hydrocarbons, high-boiling alicyclic hydrocarbons, or mixtures thereof, and / or viscosity-adjusting diluents such as ethylene glycol and diethylene glycol, and other additives may be added as needed. In this specification, when these additives are added, "phenolic resin" refers to the substance before the addition of surfactants and other additives, and the substance after the addition of the additives is referred to as a "phenolic resin composition."

[0056] The viscosity of the phenolic resin at 40° C. is preferably 5,000 MPa·s to 100,000 MPa·s, more preferably 7,000 MPa·s to 50,000 MPa·s, and even more preferably 9,000 MPa·s to 30,000 MPa·s. The moisture content of the phenolic resin is preferably 1.5% by mass to 30% by mass.

[0057] As surfactants, those generally used for making phenolic resin foams can be used, among which nonionic surfactants are effective, for example, preferably alkylene oxide as a copolymer of ethylene oxide and propylene oxide, and / or condensates of alkylene oxide and castor oil, condensation products of alkylene oxide and alkylphenols such as nonylphenol and dodecylphenol, polyoxyethylene alkyl ethers having 14 to 22 carbon atoms in the alkyl ether portion, and fatty acid esters such as polyoxyethylene fatty acid esters, organosilicon compounds such as polydimethylsiloxane, polyols, etc. These surfactants can be used alone or in combination of two or more. In addition, their usage is not particularly limited, and it is preferably used in the range of 0.3 to 10 parts by mass per 100 parts by mass of phenolic resin.

[0058] The present invention is characterized in that, when producing a phenolic resin foam, the phenolic resin or phenolic resin composition as a raw material contains a decomposition product obtained by thermally decomposing the phenolic resin foam as a part of the raw material.

[0059] The phenolic resin foam as a recycling raw material is preferably crushed before thermal decomposition to increase the surface area of ​​the granular or powdery form. The reason is that the larger the surface area, the more efficiently the decomposition reaction proceeds. In this regard, in the present invention, the phenolic resin foam is crushed rather than the phenolic resin solidified in a non-foamed state to obtain the recycling raw material. Therefore, due to the presence of bubbles and bubble films forming the foam, when the surface area of ​​the particles or powder obtained by crushing is compared with the surface area of ​​the particles or powder obtained by crushing the phenolic resin solidified in a non-foamed state, the surface area of ​​the particles or powder obtained by crushing is further increased, so the decomposition process is carried out more efficiently. The particle size of the phenolic resin foam powder as a recycling raw material is preferably 5 μm or more and 1000 μm or less in terms of average particle size, more preferably 20 μm or more and 800 μm or less, and further preferably 40 μm or more and 600 μm or less. In addition, the bulk density of the phenolic resin foam powder is preferably 10 kg / m 3 Above and 50kg / m 3 Below, more preferably 15kg / m 3 Above 45kg / m 3 Below, more preferably 20kg / m 3 Above 40kg / m 3 the following.

[0060] In the phenolic resin foam, especially its pulverized powder implemented as recycling material for thermal decomposition treatment, the composition except the phenolic resin foam can be included. The ratio of the phenolic resin foam in the pulverized powder as a whole is preferably more than 70 % by weight, more preferably more than 80 % by weight, further preferably more than 90 % by weight. It should be noted that, as the composition except the phenolic resin foam, the surface material components such as polyester nonwoven fabrics, paper, glass fiber mixed combustion paper that can be stacked on the phenolic resin foam as the raw material for recycling can also be contained in the phenolic resin foam powder.

[0061] The phenolic compound used as a solvent for thermal decomposition of the phenolic resin foam used as a recycled raw material is not particularly limited, as long as it is a phenolic compound in which at least one hydrogen atom bonded to a carbon atom of an aromatic ring is replaced by a hydroxyl group, and the phenolic compound can function as a solvent in a supercritical or subcritical state, either alone or as a mixture with other solvents, to decompose and / or solubilize the phenolic resin foam. Suitable examples of phenolic compounds used as solvents include monocyclic phenolic compounds such as phenol, cresol, xylenol, resorcinol, and alkyl-substituted phenols, and polycyclic phenolic compounds such as 1-naphthol and 2-naphthol. One or more of these can be used. Of these, phenol is preferred in terms of cost and the effect imparted by thermal decomposition.

[0062] As a solvent for thermal decomposition of a phenolic resin foam as a recycled raw material, a phenolic compound can be used alone or in a mixture with another solvent. When a mixture with another solvent is used, the other solvent can be any of water, monoalcohols such as methanol and ethanol, glycols such as ethylene glycol and propylene glycol, ketones, ethers, esters, organic acids, acid anhydrides, etc., which are commonly used as solvents in chemical reactions. In addition, a combination of multiple solvents can also be used. Among these solvents, water is preferably used in terms of the effect it imparts on decomposition and ease of acquisition. In addition, regarding the mixing ratio of the other solvent to the phenolic compound, it is preferred that the other solvent be 1 to 500 parts by mass per 100 parts by mass of the phenolic compound, and more preferably 5 to 50 parts by mass per 100 parts by mass of the phenolic compound. When the amount of the other solvent added exceeds 500 parts by mass, the decomposition rate sometimes decreases.

[0063] In the thermal decomposition of the phenolic resin foam as a recycled raw material, the ratio of the phenolic resin foam to the solvent is 50 to 2000 parts by mass, more preferably 100 to 1500 parts by mass, and even more preferably 150 to 1000 parts by mass, per 100 parts by mass of the phenolic resin foam.

[0064] When the solvent content is less than 50 parts by mass, it may become difficult to decompose the phenolic resin foam smoothly. On the other hand, when the solvent content is more than 2000 parts by mass, the energy required for heating increases, thereby sometimes increasing the processing cost and reducing the recycling rate when used as a raw material for the phenolic resin foam.

[0065] The decomposition temperature of the phenolic resin foam used as a recycled raw material is 260°C to 370°C, preferably 280°C to 360°C, and more preferably 300°C to 350°C. If the decomposition temperature is less than 260°C, the phenolic resin foam does not decompose sufficiently and is unsuitable as a raw material. If the decomposition temperature is higher than 370°C, the amount of component (A) produced increases, making it unsuitable as a raw material for the phenolic resin foam.

[0066] The pressure during the thermal decomposition of the phenolic resin foam as the raw material for recycling is more than 1.5MPa and below 20MPa, is preferably more than 2.0MPa and below 15MPa, more preferably more than 2.5MPa and below 10MPa. When being less than 1.5MPa, the phenolic resin foam is not decomposed fully sometimes and is not suitable as raw material. Even if make pressure higher than 20MPa, because the required energy of pressurization increases, so processing cost also increases.Pressure can be adjusted by the amount of temperature, phenolic resin foam and / or solvent relative to the volume of reaction vessel.

[0067] The treatment time for the thermal decomposition of the phenolic resin foam as a recycled raw material can be adjusted within a range of 60 minutes to 240 minutes, preferably 80 minutes to 220 minutes, and more preferably 100 minutes to 200 minutes. If the treatment time is shorter than 60 minutes, it is difficult to fully decompose the phenolic resin foam. Even if the reaction time is longer than 240 minutes, the amount of by-products generated will only increase.

[0068] The decomposition reaction of the phenolic resin foam as a recycled raw material is preferably carried out in a closed reaction vessel such as an autoclave because it is carried out under an inert gas atmosphere at high temperature and high pressure. Nitrogen is preferably used as the inert gas.

[0069] The decomposition rate of the phenolic resin foam used as the recycled raw material is 95% or higher, preferably 97% or higher, and more preferably 99% or higher. A decomposition rate of 95% or higher eliminates the need for removal of undecomposed residues by filtration or the like, and does not increase the viscosity of the phenolic resin when added to the phenolic resin or decrease the closed cell ratio of the phenolic resin foam. The decomposition rate can be calculated using formula (1).

[0070] Decomposition rate (%) = [weight of phenolic resin foam before decomposition (g) - weight of solid residue (g)] / weight of phenolic resin foam before decomposition (g) - (1)

[0071] By thermally decomposing a phenolic resin foam, which is a recycled raw material, at high temperatures, xanthenes are generated as by-products. By performing the decomposition within the above-mentioned temperature and time ranges, the phenolic resin foam can be decomposed at a high decomposition rate while suppressing the generation of xanthenes.

[0072] The mass proportion of xanthene contained in the decomposed product of phenolic resin foam, which serves as a recycled raw material, after thermal decomposition is from 0.01% to 4.0%, preferably from 0.05% to 3.5%, and more preferably from 0.1% to 3.0%. The lower the xanthene content, the more suitable it is for use as a recycled raw material. However, to suppress its formation to 0.01% or less, the decomposition process must be performed at a temperature below this range, making the decomposition of the phenolic resin foam difficult. When the xanthene content exceeds 4.0%, the closed cell ratio of the phenolic resin foam produced is reduced, preventing an increase in recycling efficiency.

[0073] The ratio of xanthene contained in the decomposition product can be measured by gas chromatography-mass spectrometry.

[0074] The amount of the decomposition product added as a recycled raw material may vary depending on the foaming and / or curing conditions such as temperature and residence time. However, the amount of the decomposition product added as a recycled raw material is preferably 0.1 to 20.0 parts by mass, preferably 0.5 to 15.0 parts by mass, and more preferably 1.0 to 10 parts by mass, relative to 100 parts by mass of the phenolic resin. If the amount is less than 0.1 parts by mass, the recycling rate is low, while if the amount exceeds 20.0 parts by mass, the closed cell ratio is reduced when the foam is produced.

[0075] In order to reduce the thermal conductivity of the phenolic resin foam obtained by the present invention, the phenolic resin foam preferably contains hydrocarbons, hydrofluorocarbons, chlorinated hydrofluoroolefins, non-chlorinated hydrofluoroolefins, and chlorinated hydrocarbons as a blowing agent.

[0076] The hydrocarbons are preferably cyclic or chain alkanes, alkenes, and alkynes having 3 to 7 carbon atoms, and specific examples thereof include n-butane, isobutane, cyclobutane, n-pentane, isopentane, cyclopentane, neopentane, n-hexane, isohexane, 2,2-dimethylbutane, 2,3-dimethylbutane, and cyclohexane. Among them, the pentanes such as n-pentane, isopentane, cyclopentane, and neopentane, and the butanes such as n-butane, isobutane, and cyclobutane are preferably used.

[0077] Examples of the hydrofluorocarbon include hydrofluoropropylene, hydrochlorofluoropropylene, hydrobromofluoropropylene, hydrofluorobutene, hydrochlorofluorobutene, hydrobromofluorobutene, hydrofluoroethane, hydrochlorofluoroethane, and hydrobromofluoroethane.

[0078] Examples of chlorinated hydrofluoroolefins include HCFO-1224yd(Z) (chemical name: (Z)-1-chloro-2,3,3,3-tetrafluoropropene) and / or 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd, for example, Honeywell as an E-form (HCFO-1233zd(E))) which have extremely low thermal conductivity as a blowing agent. (a product of Solstice (trademark) LBA manufactured by Japan Co., Ltd.), 1,1,2-trichloro-3,3,3-trifluoropropene (HCFO-1213xa), 1,2-dichloro-3,3,3-trifluoropropene (HCFO-1223xd), 1,1-dichloro-3,3,3-trifluoropropene (HCFO-1223za), 1-chloro-1,3,3,3-tetrafluoropropene (HCFO-1224zb), 2,3,3-trichloro-3-fluoropropene (HCFO-1231xf), 2,3-dichloro-3,3-difluoropropene (HCFO-1232xf), 2-chloro-1,1,3-trifluoropropene (HCFO-1233xc), 2-chloro-1,3,3-trifluoropropene (HCFO-1224zb), -1233xe), 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), 1-chloro-1,2,3-trifluoropropene (HCFO-1233yb), 3-chloro-1,1,3-trifluoropropene (HCFO-1233yc), 1-chloro-2,3,3-trifluoropropene (HCFO-1233yd), 3-chloro-1,2,3-trifluoropropene (HCFO-1233ye), 3-chloro-2,3,3-trifluoropropene (HCFO-1233yf), 1-chloro-1,3,3-trifluoropropene (HCFO-1233zb), and 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd), and their stereoconfigurational isomers, i.e., E-isomers or Z-isomers, or a mixture thereof can be used. Furthermore, (E)-1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd(E)) can also be mentioned.

[0079] Examples of non-hydrochlorinated fluoroolefins include 1,3,3,3-tetrafluoro-1-propene (HFO-1234ze, for example, Honeywell as an E-form (HFO-1234ze (E)) The products include 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz, for example, Opteon (trademark) 1100 manufactured by Chemours Co., Ltd. as a Z-isomer (HFO-1336mzz(Z)), 2,3,3,3-tetrafluoro-1-propene (HFO-1234yf), 1,1,3,3,3-pentafluoropropene (HFO-1225zc), 1,3,3,3-tetrafluoropropene (HFO-1234ze), 3,3,3-trifluoropropene (HFO-1243zf), and 1,1,1,4,4,5,5,5-octafluoro-2-pentene (HFO-1438mzz). Stereoisomers of these, i.e., either the E-isomer or the Z-isomer, or a mixture thereof, can be used.

[0080] When a hydrochlorinated fluoroolefin or a non-hydrochlorinated fluoroolefin is used, the content of the blowing agent in the total blowing agent is preferably 30% by mass or more.

[0081] As chlorinated hydrocarbons, linear or branched chlorinated aliphatic hydrocarbons with 2 to 5 carbon atoms are preferably used. The number of bonded chlorine atoms is preferably 1 to 4. Examples include ethylene dichloride, chloropropane, isochloropropane, chlorobutane, isochlorobutane, chloropentane, and isochloropentane. Among these, propyl chloride and isopropyl chloride are more preferably used as chloropropanes.

[0082] The above-mentioned foaming agents may be used alone or in combination of two or more and may be selected arbitrarily.

[0083] When producing the phenolic resin foam obtained by the present invention, the preferred amount of the blowing agent in the foamable phenolic resin composition is 10.0 parts by mass or less, more preferably 4.5 parts by mass or more and 10.0 parts by mass or less, and even more preferably 5.0 parts by mass or more and 9.0 parts by mass or less, relative to 100 parts by mass of the phenolic resin or the phenolic resin composition.

[0084] In the present embodiment, when manufacturing the phenolic resin foam obtained by the present invention, a foaming nucleating agent can be further used. As a foaming nucleating agent, a gaseous foaming nucleating agent such as nitrogen, helium, argon, air, etc., whose boiling point is 50°C or lower than that of the foaming agent, can be added. In addition, inorganic powders such as aluminum hydroxide powder, aluminum oxide powder, calcium carbonate powder, talc, white clay (kaolin), silica powder, silica sand, mica, calcium silicate powder, wollastonite, glass powder, glass beads, fly ash, silica fume, gypsum powder, borax, slag powder, alumina cement, Portland cement, and solid foaming nucleating agents such as organic powders such as the crushed powder of the phenolic resin foam can also be added. These can be used alone or in combination without distinguishing between gas and solid. The timing of adding the foaming nucleating agent can be arbitrarily determined, as long as it is supplied to the mixer for mixing to obtain the foamable phenolic resin composition.

[0085] Taking the amount of the foaming agent as 100 mass%, the amount of the gaseous foaming nucleating agent added relative to the foaming agent is preferably 0.2 mass% to 1.0 mass%, more preferably 0.3 mass% to 0.5 mass%. Furthermore, the amount of the solid foaming nucleating agent added relative to 100 mass parts of the phenolic resin or phenolic resin composition is preferably 3.0 mass parts to 10.0 mass parts, more preferably 4.0 mass parts to 8.0 mass parts.

[0086] When manufacturing the phenolic resin foam obtained by the present invention, as an acidic curing agent added to the foamable phenolic resin composition, it is necessary to use an organic acid as an acid component. The organic acid is preferably an aryl sulfonic acid or its anhydride. As aryl sulfonic acid and its anhydride, there can be mentioned: toluenesulfonic acid, xylenesulfonic acid, phenolsulfonic acid, substituted phenolsulfonic acid, xylenolsulfonic acid, substituted xylenolsulfonic acid, dodecylbenzenesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, etc., and their anhydride. These can be used alone or in combination of two or more. It should be noted that, in the present embodiment, as a curing aid, resorcinol, cresol, salicyl alcohol (o-hydroxymethylphenol), p-hydroxymethylphenol, etc. can be added. In addition, these curing agents can be diluted by solvents such as ethylene glycol and diethylene glycol.

[0087] The amount of the acidic curing agent used varies depending on its type. When a mixture of 80% by mass of xylenesulfonic acid and 20% by mass of diethylene glycol is used, the amount used is preferably 6 parts by mass or more and 16 parts by mass or less, and more preferably 8 parts by mass or more and 13 parts by mass or less, per 100 parts by mass of the phenolic resin or the phenolic resin composition.

[0088] As the surface material at least on the upper surface and the lower surface of the phenolic resin foam obtained by the present invention, a surface material (flexible surface material) with flexibility can be used. As the flexible surface material used, preferably non-woven fabrics and woven fabrics whose main component comprises polyester, polypropylene, nylon, etc., and / or papers such as kraft paper, glass fiber mixed paper, calcium hydroxide paper, aluminum hydroxide paper, magnesium silicate paper, and / or non-woven fabrics of inorganic fibers such as glass fiber non-woven fabrics, etc., these can also be mixed (or stacked) and used. Wherein, when peeling off the surface material from the phenolic resin foam laminate obtained and only utilizing the parent material, it is preferably cheap paper that can be discarded after peeling. These surface materials are usually provided in the form of rolls. And then, as the flexible surface material, it can be used to mix and knead additives such as flame retardants. It should be noted that the bonding method of the surface material and the phenolic resin foam is not particularly limited, and can be a person utilizing the fixing force of the phenolic resin foam when the surface material surface is thermally cured and / or a person using adhesives such as epoxy resins.

[0089] Next, the method for producing the phenolic resin foam obtained by the present invention will be described.

[0090] The method for producing the phenolic resin foam obtained by the present invention can suitably adopt a continuous production method, which comprises: a mixing step of mixing a phenolic resin, a decomposition product as a recycled raw material, a foaming agent, and an acidic curing agent containing an organic acid using a mixer to obtain a foamable phenolic resin composition; a spraying step of spraying the foamable phenolic resin composition onto a lower surface material; a step of foaming and curing the foamable phenolic resin composition sprayed onto the lower surface material while performing a pre-forming step; a step of performing a main forming step as a main step for carrying out the foaming and curing reaction; and a subsequent step of post-curing for releasing moisture in the foamable phenolic resin composition.

[0091] In the continuous production method, it is preferred that the foamable phenolic resin composition sprayed onto the lower surface material is covered with the upper surface material, and then pre-formed in a flat manner in the vertical direction while being foamed and cured. Thereafter, in the main forming step, foaming and curing are performed while forming into a plate shape.

[0092] The method of adding the decomposed product to the phenolic resin or phenolic resin composition and kneading the mixture is not particularly limited. Mixing may be performed using a hand mixer, a paddle mixer, or the like. A twin-screw extruder or a kneading machine may also be used.

[0093] The mixer used to obtain the foamable phenolic resin composition is not particularly limited, and the mixer disclosed in Japanese Patent Application Laid-Open No. 10-225993 can be used. Specifically, the mixing section and the dispensing section are each equipped with a temperature regulating jacket for temperature adjustment. A thermometer is installed at the outlet of the mixing section (the stirring end section) before entering the dispensing section to control the temperature of the foamable phenolic resin composition.

[0094] In the preforming step and the main forming step of the continuous production method, various methods can be used to perform the preforming and main forming, respectively, such as methods using a slatted double conveyor, methods using metal rollers or steel plates, and methods using a combination of these, depending on the purpose of production. For example, in the case of forming using a slatted double conveyor, the foamable phenolic resin composition covered with upper and lower surface materials can be continuously introduced into the slatted double conveyor, and then heated while applying pressure in the upper and lower directions to adjust to a predetermined thickness, and simultaneously foamed and cured to form into a sheet.

[0095] The heating temperature control conditions in the preforming step are preferably 45° C. or higher and 70° C. or lower in terms of space temperature.

[0096] The heating and temperature control conditions for the main forming process following the pre-forming process are preferably 70°C or higher and 100°C or lower. In this range, the main forming process is performed using an endless steel belt double conveyor, a slat double conveyor, or rollers. If the temperature is 70°C or higher, curing tends to be accelerated. On the other hand, if the temperature exceeds 100°C, the curing reactivity increases, allowing for high-speed forming. However, the foam is excessively affected by the reaction heat within the foam during foaming and curing, resulting in a decrease in the closed-cell ratio of the plate-shaped phenolic resin foam, that is, a decrease in thermal insulation performance.

[0097] The post-curing step is performed after the pre-forming step and the main forming step. The temperature of the post-curing step is preferably 90° C. or higher and 120° C. or lower.

[0098] [Example]

[0099] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0100] Synthesis of phenolic resin

[0101] 3,500 kg of a 52% by mass formaldehyde aqueous solution (52% by mass formalin) and 2,510 kg of 99% by mass phenol (including water as an impurity) were added to a reactor and stirred using a propeller-type stirrer. The internal temperature of the reactor was adjusted to 40°C using a temperature controller. Subsequently, a 48% by mass sodium hydroxide aqueous solution was added until the pH reached 8.7, and the temperature was then raised to 85°C for reaction. When the Ostwald viscosity of the reaction solution reached 120 square millimeters per second (=120 mm2 / s, measured at 25°C), the reaction solution was cooled, and urea was added to achieve a urea content of 4.6% by mass in the phenolic resin. The reaction solution was then cooled to 30°C, and a 50% by mass aqueous solution of p-toluenesulfonic acid monohydrate was added until the pH reached 6.3. The resulting reaction solution was concentrated using a thin-film evaporator, and the weight-average molecular weight and viscosity were measured using the following methods. As a result, a phenolic resin having a weight average molecular weight of 1,800 and a viscosity at 40° C. of 12,000 MPa·s was obtained.

[0102] <Weight average molecular weight>

[0103] The weight-average molecular weight (Mw) of the phenolic resin was determined by gel permeation chromatography (GPC) under the following conditions using a calibration curve obtained using the following standard substances (standard polystyrene, 2-hydroxybenzyl alcohol, and phenol). Pretreatment: Dissolve approximately 10 mg of the phenolic resin in 1 ml of N,N-dimethylformamide (Wako Pure Chemical Industries, Ltd., for high-performance liquid chromatography) and filter through a 0.2 μm membrane filter to obtain the measurement solution.

[0104] Measurement conditions:

[0105] Measuring device: Shodex System 21 (manufactured by Showa Denko K.K.)

[0106] Column: Shodex asahipak GF-310HQ (7.5mmI.D.×30cm)

[0107] Eluent: 0.1% by mass of lithium bromide dissolved in N,N-dimethylformamide (manufactured by Wako Pure Chemical Industries, Ltd., for high performance liquid chromatography) was used.

[0108] Flow rate: 0.6ml / min

[0109] Detector: RI detector

[0110] Column temperature: 40°C

[0111] Standard substances: Standard polystyrene (Shodex standard SL-105, manufactured by Showa Denko K.K.), 2-hydroxybenzyl alcohol (99% product, manufactured by Sigma-Aldrich Co.), phenol (special grade, manufactured by Kanto Chemical Co., Ltd.)

[0112] Viscosity

[0113] The viscosity of the phenolic resin was determined by using a rotational viscometer (R-100 model, manufactured by Toki Sangyo Co., Ltd., with a rotor of 3°×R-14) and stabilizing the viscosity at 40°C for 3 minutes.

[0114] <Water content of phenolic resin>

[0115] A phenolic resin solution was prepared by dissolving it in dehydrated methanol (manufactured by Kanto Chemical Co., Ltd.) at a concentration of 3% to 7% by mass. The moisture content of the phenolic resin was determined by subtracting the water content in the dehydrated methanol from the moisture content of the solution. This was measured using a Karl Fischer moisture meter (MKC-510, manufactured by Kyoto Denshi Kogyo Co., Ltd.).

[0116] <Ratio of phenolic resin foam in the entire pulverized powder>

[0117] Weigh 10 g of the pulverized powder, and calculate the weight ratio of the powder that passes through a 1 mm sieve as the ratio of the phenolic resin foam. Calculate the average of three times. In this case, the surface material, especially, does not become finer even after the pulverization process, and therefore cannot pass through the sieve and is removed.

[0118] <Average particle size of phenolic resin foam powder>

[0119] The particle size distribution of the phenolic resin foam powder was measured after dispersion in water, with the cumulative 50% particle size being the average particle size. The measurement was performed using a particle size distribution meter (Microtrac MT3300EXII-SDC) with a particle refractive index of 1.81 and a measurement time of 30 seconds. The average of two measurements was calculated.

[0120] (Example 1)

[0121] <Decomposition of phenolic resin foam as a recycling raw material (1)>

[0122] After removing the surface material of the phenolic foam (made by Asahi Kasei Building Materials Co., Ltd.; Neoma FOAM), it was cut into pieces of about 10 cm3 in size and crushed for 10 minutes using a Henschel mixer (made by Mitsui Miike Manufacturing Co., Ltd.; model FM20B) to produce a cross-linked and cured phenolic resin foam powder. The average particle size of the obtained phenolic resin foam powder was 174 μm. After adding 100 g of the phenolic resin foam powder, 620 g of phenol, and 100 g of water to an autoclave (content volume 2 L), the autoclave was heated to an internal temperature of 350°C, thereby raising the internal pressure of the reactor to 5.6 MPa, thereby achieving a high temperature and high pressure state. After the reaction system was kept at 350°C and 5.6 MPa for 3 hours, it was cooled and returned to room temperature and pressure, and the recovered product was filtered to obtain a decomposed product. At this time, the decomposition rate of the phenolic resin foam was 99.5%. The ratio of the phenolic resin foam in the pulverized powder of the phenolic resin foam after the surface material was removed and subjected to thermal decomposition as a recycled material was 100.0% by weight.

[0123] <Production of Phenolic Resin Foam Obtained by the Present Invention>

[0124] Relative to 100 mass parts of phenolic resin, the composition of the block copolymer of ethylene oxide-propylene oxide 50% and polyoxyethylene dodecylphenyl ether 50% respectively containing as surfactant in mass ratio is mixed with the ratio of 2.8 mass %.With the addition of decomposition treatment material being 5.0 mass parts relative to 100 mass parts of phenolic resin, in this mixture, add decomposition treatment material, mix by twin-screw extruder (Technovel Co., Ltd. system), obtain phenolic resin composition.Relative to this phenolic resin composition 100 mass parts, add 6.0 mass parts of mixture of cyclopentane 75 mass % and isobutane 25 mass % as blowing agent, add nitrogen as gas foaming nucleating agent that is 0.4 mass % relative to blowing agent, and then add 10 mass parts of composition of the mixture comprising xylene sulfonic acid 80 mass % and diethylene glycol 20 mass % as acidic curing agent, and supply to speed variable mixing head. Mixing is carried out, and the foamable phenolic resin composition obtained is distributed through a multi-channel distribution pipe and supplied to the moving lower surface material. It should be noted that the mixer (mixer) uses the one disclosed in Japanese Patent Laid-Open No. 10-225993. That is, the following mixer is used: the upper side of the mixer has an inlet for the phenolic resin composition and the foaming agent containing the foaming nucleating agent, and the side near the center of the stirring part where the rotor stirs is equipped with an inlet for the acidic curing agent. The part after the stirring part is connected to the nozzle for spraying the foamable phenolic resin composition. In addition, the mixer is composed of a mixing part (front section) up to the acidic curing agent inlet, a mixing part (back section) with the acidic curing agent inlet to the stirring end, and a distribution part with the stirring end to the nozzle. The mixer is composed of these, and respectively, a pressure gauge is provided on the upper side of the mixer, and a thermometer is provided on the stirring end. In addition, the distribution part has a plurality of nozzles at the front end and is designed in a way that the foamable phenolic resin composition obtained is evenly distributed. Here, the mixer and the nozzle can adjust the temperature by temperature-controlled water, and the temperature of the temperature-controlled water is 25°C. The rotation speed of the mixing head is set to 500rpm. The foamable phenolic resin composition supplied to the lower surface material is introduced into the pre-forming process, and the space temperature of the pre-forming process at this time is set to 65°C. It should be noted that the pre-forming is carried out from above the upper surface material through a free roller. Then, it is introduced into a slat-type double conveyor (formal forming process) with a space temperature heated to 85°C in a manner of being clamped by two pieces of surface material. In the formal forming process, after curing with a residence time of 10 minutes, it is cut in a direction perpendicular to the direction of travel, thereby obtaining a plate-shaped phenolic resin foam intermediate with a length of 1820mm that is easy to operate. Thereafter, it is further cured in an oven at 110°C for 3 hours (post-curing process) to obtain a plate-shaped phenolic resin foam with a thickness of 50mm.It should be noted that polyester nonwoven fabric (ELTAS E05060 manufactured by Asahi Kasei Corporation, with a basis weight of 60 g / m2) was used as the surface material for both the upper surface material and the lower surface material. 2 ).

[0125] Gas chromatography-mass spectrometry analysis

[0126] The solid residue was removed from the decomposed product by filtration, and the product was diluted with distilled water and measured.

[0127] Gas chromatography apparatus Agilent Technologies 7890B

[0128] Column DB-5 (30m×0.25mmφ, film thickness 1μm)

[0129] Column temperature 40°C (5 min) → temperature increase at 10°C / min → 300°C (29 min)

[0130] Flow rate 1ml / min

[0131] Inlet temperature 320℃

[0132] Split ratio 1 / 50

[0133] Injection volume 1μL

[0134] Mass spectrometer Agilent Technologies, 5977

[0135] Interface temperature 300℃

[0136] Ionization EI 70eV

[0137] Scan range m / z 10~800

[0138] Ion source temperature 240°C

[0139] <Pyrolysis gas chromatography-mass spectrometry>

[0140] The surface material was peeled off from the phenolic resin foam, and 0.15 mg of the foam was scraped off and measured.

[0141] Measurement conditions:

[0142] Pyrolysis device Frontier-lab, EGA / PY-3030D

[0143] Heating conditions: 600°C

[0144] Gas chromatography apparatus Agilent Technologies 7890A

[0145] Column DB-1 (30m×0.25mmφ, film thickness 0.25μm)

[0146] Column temperature 50°C (5 min) → 20°C / min → 320°C (11.5 min)

[0147] Flow rate 1ml / min

[0148] Inlet temperature 320℃

[0149] Split ratio 1 / 50

[0150] Injection volume: approximately 0.15 mg

[0151] Mass spectrometer JEOL RESONANCE, JMS-Q1500GC

[0152] Interface temperature 320℃

[0153] Ionization EI 70eV

[0154] Scan range m / Z 10~800

[0155] Ion source temperature 240°C

[0156] <Measurement of Density of Phenolic Resin Foam>

[0157] The mass and apparent volume of a 200 mm square phenolic resin foamed body were determined by removing the surface material from the sample in accordance with JIS K7222.

[0158] Thermal conductivity

[0159] The thermal conductivity in the thickness direction of the phenolic resin foam was measured in an environment at 23° C. by the following method in accordance with JIS A1412-2:1999. The specific procedure is as follows.

[0160] Cut a 300 mm square of phenolic resin foam and place the test piece in an atmosphere of 23±1°C and 50±2% humidity. Thereafter, measure the change in weight over time every 24 hours, confirm the state and adjust the condition until the weight change after 24 hours is less than 0.2% by mass. The state-adjusted composite test piece is introduced into a thermal conductivity device similarly placed in an atmosphere of 23±1°C and 50±2% humidity. If the thermal conductivity measuring device is not placed in a room where the composite test piece is placed and the temperature is controlled at 23±1% and 50±2%, the test piece that has been confirmed and adjusted in the above atmosphere is quickly placed in a polyethylene bag and the bag is closed. The bag is taken out from the bag within 1 hour and the thermal conductivity is quickly measured. Thermal conductivity at 23°C was measured using a one-sample-object measurement device (Eiko Seiki Co., Ltd., trade name "HC-074 / FOX304") under conditions of a low-temperature plate at 13°C and a high-temperature plate at 33°C.

[0161] <Closed-cell ratio of phenolic resin foam>

[0162] The closed-cell ratio of the phenolic resin foam was determined according to ASTM-D-2856 (C method). Specifically, after removing the surface material from the phenolic resin foam, a cylindrical sample with a diameter of 35 mm to 36 mm was dug out with a cork borer, and the sample volume was measured using an air comparison pycnometer (manufactured by Tokyo Science, Model 1000). In addition, the volume of the wall (excluding bubbles and voids) was calculated based on the mass of the sample and the density of the phenolic resin cured product. Then, the apparent volume was calculated based on the outer dimensions of the sample. Then, the value obtained by subtracting the volume of the wall from the sample volume was divided by the apparent volume, and the resulting value was used as the closed-cell ratio. Here, the density of the phenolic resin is 1.3 kg / L.

[0163] (Example 2)

[0164] A phenolic resin foam was obtained in the same manner as in Example 1 except that the amount of the decomposed product added was 10.0 parts by mass relative to 100 parts by mass of the phenolic resin.

[0165] (Example 3)

[0166] A phenolic resin foam was obtained in the same manner as in Example 1 except that the decomposition temperature of the phenolic resin foam as the recycled raw material was set to 300° C. and the pressure was set to 2.6 MPa.

[0167] (Example 4)

[0168] A phenolic resin foam was obtained in the same manner as in Example 1 except that the amount of phenolic resin foam powder obtained when the phenolic resin foam serving as a recycled raw material was 50 g.

[0169] (Example 5)

[0170] A phenolic resin foam was obtained in the same manner as in Example 1 except that the phenolic resin foam as a recycled raw material was thermally decomposed by the method described below in <Decomposition of phenolic resin foam as recycled raw material (2)>.

[0171] <Decomposition of phenolic resin foam as a recycling raw material (2)>

[0172] A decomposition product was obtained in the same manner as in <Decomposition of Phenolic Resin Foam (1)>, except that a phenolic resin foam (Neoma FOAM, manufactured by Asahi Kasei Building Materials Co., Ltd.) was crushed in a state where a surface material was laminated thereon. The decomposition product was 99.4% in this case. The proportion of the phenolic resin foam in the crushed powder of the phenolic resin foam with the surface material, which was subjected to thermal decomposition as a recycling material, was 97.1% by weight.

[0173] (Example 6)

[0174] A phenolic resin foam was obtained in the same manner as in Example 1 except that the pulverization time in producing the phenolic resin foam powder was 30 minutes, the average particle size was 62 μm, and the decomposition time was 60 minutes.

[0175] (Comparative Example 1)

[0176] A phenolic resin foam was obtained in the same manner as in Example 1 except that the amount of the decomposition product added was 22.0 parts by mass relative to 100 parts by mass of the phenolic resin.

[0177] (Comparative Example 2)

[0178] The phenolic resin foam was thermally decomposed in the same manner as in Example 1, except that the decomposition temperature of the decomposition product was set at 250°C and the pressure was set at 2.3 MPa. Since the phenolic resin foam used as the recycled raw material was not decomposed, the viscosity of the phenolic resin to which the decomposition product was added increased, and a good phenolic resin foam could not be obtained.

[0179] (Comparative Example 3)

[0180] A phenolic resin foam was obtained in the same manner as in Example 1 except that 1240 g of phenol was used for the thermal decomposition of the phenolic resin foam as the recycled raw material, the decomposition temperature was 380° C., the pressure was 0.6 MPa, and the decomposition time was 10 minutes.

[0181] (Comparative Example 4)

[0182] The phenolic resin foam, which was a recycled raw material, was extruded through a co-rotating twin-screw extruder (40φ, L / D=50, manufactured by Technovel Co., Ltd.) set at 300° C. to undergo decomposition treatment. The solvent volatilized during extrusion, and no decomposed product was obtained.

[0183] (Comparative Example 5)

[0184] A phenolic resin foam was obtained in the same manner as in Example 1 except that the decomposition product was not added.

[0185] The decomposition products of Examples 1 to 6 and Comparative Examples 1 to 5 were analyzed for decomposition rate and gas chromatography-mass spectrometry. The phenolic resin foam was also measured for thermal conductivity, density, closed cell ratio, and pyrolysis gas chromatography-mass spectrometry. The results are shown in Table 1. Table 1 also summarizes the decomposition treatment conditions and decomposition rate results for the phenolic resin foam powder.

[0186] [Table 1]

[0187]

Claims

1. A phenolic resin foam, wherein: When a phenolic resin foam is subjected to pyrolysis gas chromatography-mass spectrometry analysis under heating conditions of 600° C., where the area value of the signal of structural formula (A) is defined as [A] and the area value of the signal of structural formula (B) is defined as [B], [A] / [B] is 2.0 or more and 15 or less, (A) (B) 2 . The phenolic resin foam according to claim 1 , wherein the thermal conductivity is 0.016 W / (m·K) or more and 0.026 W / (m·K) or less.

3. The phenolic resin foam according to claim 1 or 2, wherein the closed cell ratio is 85% or more.

4. The phenolic resin foam according to claim 1 or 2, having a density of 20 kg / m 3 Above and 70kg / m 3 the following.

5. A method for thermal decomposition treatment of a phenolic resin foam, characterized in that: A phenolic resin foam is heated and pressurized in a mononuclear phenol compound or in a solution of water and a mononuclear phenol compound under the conditions of 260° C. to 370° C., 1.5 MPa to 20 MPa, and 60 minutes to 240 minutes, thereby obtaining a decomposed product with a decomposition rate of 95% or more.

6. A decomposition product obtained by thermally decomposing a phenolic resin foam, the decomposition product containing 0.01% to 4.0% of xanthene.

7. The method for producing a phenolic resin foam according to claim 1 or 2, wherein: The decomposition product according to claim 6 is added in an amount of 0.1 parts by mass to 20.0 parts by mass based on 100 parts by mass of the phenolic resin, and the mixture is foamed and cured.

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