CN117794989A

CN117794989A - Phenolic resin foam

Info

Publication number: CN117794989A
Application number: CN202180101154.8A
Authority: CN
Inventors: 后藤和佳; 平松信希; 三堀寿
Original assignee: Asahi Kasei Construction Materials Corp
Current assignee: Asahi Kasei Construction Materials Corp
Priority date: 2021-08-12
Filing date: 2021-08-12
Publication date: 2024-03-29
Also published as: WO2023017603A1; KR20240004685A; JPWO2023017603A1

Abstract

A phenolic resin foam satisfying the following (1), (2) and (3), having a closed cell content of 80% or more and a foam density of 20 to 80kg/m ³ . (1) The metal compound in the outermost layer of the phenolic resin foam is present in a ratio of 0.5 to 25.0%. (2) The metal compound in the center layer of the phenolic resin foam is present in a ratio of 0.5 to 15.0%. (3) The average cell diameter of the cross section of the phenolic resin foam, which is cut horizontally from the outermost layer in the thickness direction by 5mm, is 50-120 mu m.

Description

Phenolic resin foam

Technical Field

The present invention relates to a phenolic resin foam which has excellent alkali resistance and is suitably used as a heat insulating material for building which can be suitably used in a concrete casting method such as a wet external heat insulating method.

Background

Conventionally, glass wool and foamed resin molded articles have been widely used as heat insulating materials for buildings. As the external heat insulating construction method, two kinds of dry external heat insulating construction methods and wet external heat insulating construction methods are known, and inexpensive glass wool is mainly used for the dry external heat insulating construction method. However, if the glass wool contains moisture in the wall body and becomes heavy, the glass wool cannot maintain its shape and descends to the lower side of the wall, and it is difficult to maintain its shape for a long period of time, and there is a problem that the heat insulating effect is remarkably deteriorated for a long period of time.

On the other hand, as a wet external heat insulation construction method, patent document 1 discloses a wet external heat insulation construction method in which a mortar layer is provided on a heat insulation board formed of a foamed resin molded body or the like, and a glass fiber web is disposed to provide mortar on the surface.

In the wet external heat insulation construction method of patent document 1, a glass fiber web is used as a mesh formed by providing a mortar layer on a heat insulation material. By disposing the glass fiber net, peeling of the heat insulating material and the mortar layer thereon can be prevented. However, there is a problem that the strength of the glass fiber web itself may be insufficient, the strength of the glass fiber web may be lowered by the alkali component derived from the mortar, and the mortar layer may be peeled off for a long period of time.

Phenolic resin foam is used as a heat insulating material for building purposes for reasons such as flame retardancy and maintenance of long-term heat insulating properties. However, the phenolic resin foam preferably has higher alkali resistance under severe use conditions in which the alkali concentration is relatively high and the temperature is high. Under such conditions, when the phenolic resin foam is directly laminated with mortar, there is a risk that the mortar will fall off after construction due to a decrease in the strength of the phenolic resin foam itself.

As another method for solving the deterioration of the phenolic resin foam due to alkali, there is considered a method of reducing the water absorption rate of the foam and making the alkali component less likely to penetrate into the foam. Patent document 2 discloses a method for reducing the water absorption by adding a specific metal salt to a phenolic resin foam.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2007-231723

Patent document 2: japanese patent laid-open No. 2007-131859

Disclosure of Invention

Problems to be solved by the invention

Patent document 2 discloses calcium carbonate as a metal salt added to a phenolic resin foam, but the phenolic resin foam has a problem that deterioration due to alkali cannot be sufficiently suppressed because the presence ratio of calcium carbonate in the surface layer portion is insufficient.

Accordingly, an object of the present invention is to provide a phenolic resin foam which has improved alkali resistance in a surface layer portion of the phenolic resin foam and is excellent in heat insulation.

Solution for solving the problem

The present inventors have made intensive studies to achieve the above object, and as a result, have found that a method for improving alkali resistance and maintaining excellent heat insulating properties as compared with conventional phenolic resin foams can be achieved by adding a specific metal compound to a phenolic resin, particularly by increasing the metal compound content of the outermost layer portion in contact with alkali. The present invention configured to solve the above problems is as follows.

[1]

A phenolic resin foam satisfying the following (1), (2) and (3), having a closed cell content of 80% or more and a foam density of 20 to 80kg/m ³ 。

(1) The metal compound in the outermost layer of the phenolic resin foam is present in a ratio of 0.5 to 25.0%.

(2) The metal compound in the center layer of the phenolic resin foam is present in a ratio of 0.5 to 15.0%.

(3) The average cell diameter of the cross section of the phenolic resin foam cut parallel to the outermost layer at a position 5mm in the thickness direction from the outermost layer is 50 to 120 [ mu ] m.

[2]

The phenolic resin foam of [1], wherein the thermal conductivity at 23℃is 0.0260W/(mK) or less.

[3]

The phenolic resin foam of [1] or [2], wherein the presence ratio of the metal compound at the outermost layer of the phenolic resin foam is greater than the presence ratio of the metal compound at the center layer of the phenolic resin foam.

[4]

The phenolic resin foam of any one of [1] to [3], wherein the metal compound is: the metal of the metal compound is at least one metal compound selected from the group consisting of calcium, magnesium, zinc, barium, aluminum, iron, sodium, and potassium, and is combined with at least one metal selected from the group consisting of oxides, chlorides, sulfates, and carbonates.

[5]

The phenolic resin foam of any one of [1] to [4], wherein the strength retention of tensile strength after alkali resistance test is 30% or more.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a phenolic resin foam excellent in alkali resistance and a method for producing the same can be provided by effectively distributing a specific metal compound in the thickness direction of the phenolic resin foam.

Detailed Description

The mode for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. The present invention is not limited to the following embodiments.

The metal element of the metal compound in the present embodiment is preferably 1 selected from the group consisting of calcium, magnesium, zinc, barium, aluminum, iron, sodium, and potassium. In addition, the metal compound is preferably selected from the group consisting of oxides, chlorides, sulphates and carbonates of the above metals. As more preferable examples among them, calcium sulfate, magnesium sulfate, iron sulfate, sodium sulfate and potassium sulfate are cited, and among them, calcium sulfate is most preferable. These metal compounds may be used alone or in combination. The metal compound contained in the phenolic resin foam can be identified by using a commonly used X-ray diffraction method (XRD) or the like.

In this embodiment, the metal compound present in the outermost layer of the phenolic resin foam is present in a range of 0.5 to 25.0%, preferably 0.5 to 20.0%, more preferably 1.0 to 20.0%, even more preferably 3.0 to 20.0%, and most preferably 5.0 to 20.0%. In this range, the metal compound is present in the outermost layer, and thus, the alkali resistance can be sufficiently exhibited even in a small amount. If the presence ratio of the metal compound is less than 0.5%, the metal compound is not sufficiently present in the outermost layer, and thus the alkali resistance effect cannot be exhibited. If the presence ratio of the metal compound exceeds 25.0%, the heat insulating property may be deteriorated due to heat conduction of the metal compound, and the bubble film may be broken with the metal compound as a starting point, so that the closed cell ratio may be lowered, which is not preferable. Here, the outermost layer of the phenolic resin foam means the outermost layer of the surface of the phenolic resin foam orthogonal to the thickness direction, and the presence ratio of the metal compound is determined by performing an average of the respective evaluations on the upper and lower surfaces. The method for measuring the presence ratio of the metal compound in the outermost layer will be specifically described in examples described later.

In the phenolic resin foam of the present embodiment, the metal compound in the center layer is present in a ratio of 0.5 to 15.0%, preferably 0.5 to 10.0%, more preferably 3.0 to 10.0%, and most preferably 5.0 to 10.0%. If the presence ratio of the metal compound contained in the center layer exceeds 15.0%, the bubble film tends to be broken with the metal compound as a starting point, and therefore the closed cell ratio of the phenolic resin foam and the thermal conductivity tend to be poor. Therefore, the presence ratio of the metal compound contained in the center layer is not preferable to exceed 15.0%. In addition, if the presence ratio of the metal compound contained in the center layer is less than 0.5%, the presence ratio of the metal compound in the outermost layer of the natural phenolic resin foam is also reduced, and thus it is difficult to obtain the effect of adding the metal compound. It is not preferable that the metal compound contained in the center layer is present at a ratio of less than 0.5%. The center layer is a layer that is located at the center in the thickness direction of the phenolic resin foam and is parallel to the outermost layer. The method for measuring the presence ratio of the metal compound in the center layer will be specifically described in examples described later.

In the phenolic resin foam of the present embodiment, the presence ratio of the metal compound in the outermost layer of the phenolic resin foam is preferably greater than the presence ratio of the metal compound in the center layer. By satisfying this condition, the metal compound is effectively distributed in the thickness direction of the phenolic resin foam, and thus the phenolic resin foam is easily provided with both alkali resistance and maintenance of excellent heat insulating properties, and the effect is further increased, which is preferable. The value obtained by dividing the presence ratio of the metal compound in the outermost layer of the phenolic resin foam by the presence ratio of the metal compound in the center layer is preferably greater than 1.00, more preferably 1.10 or more, still more preferably 1.30 or more, particularly preferably 1.60 or more, and most preferably 1.70 or more.

In the phenolic resin foam of the present embodiment, the average cell diameter of the cross section of the phenolic resin foam cut parallel to the outermost layer at a position 5mm in the thickness direction from the outermost layer (after the surface material is peeled off in the case of containing the surface material) is in the range of 50 to 120 μm, preferably in the range of 50 to 110 μm, more preferably in the range of 70 to 110 μm, still more preferably in the range of 70 to 100 μm, and most preferably in the range of 80 to 100 μm. If the average cell diameter at this position falls within this range, the content of the metal compound in the phenolic resin foam on the surface layer side can be increased as compared with this position. Therefore, it is found that the surface layer side of the phenolic resin foam can exhibit alkali resistance. When the average cell diameter is less than 50 μm, the density of the outermost layer is too high, and therefore the foamable phenolic resin composition tends to bleed out from the surface of the surface material, and the device may be contaminated when the foam is molded. In addition, when the average bubble diameter is larger than 120 μm, the presence ratio of the metal compound in the outermost layer is lowered, and alkali resistance may not be exhibited. Therefore, the average bubble diameter of more than 120 μm is not preferable.

The closed cell ratio of the phenolic resin foam in the present embodiment is 80% or more, preferably 85% or more, more preferably 90% or more, and most preferably 95% or more. If the closed cell ratio is too low, the foaming agent encapsulated in the bubbles tends to be easily replaced with air, and thus the thermal conductivity increases, or the rate of deterioration of the thermal conductivity after a long period of time increases, or the compressive strength tends to decrease. The method for measuring the closed cell ratio will be specifically described in examples described below.

The density of the phenolic resin foam in the present embodiment was 20kg/m ³ ～80kg/m ³ Preferably 25kg/m ³ ～55kg/m ³ Further preferably 27kg/m ³ ～45kg/m ³ Most preferably 27kg/m ³ ～40kg/m ³ . If the density is less than 20kg/m ³ The strength is low and the foam is easily broken during transportation or construction. In addition, if the density is low, the bubble film tends to be thin. If the cell film is thin, the blowing agent in the foam is easily replaced with air, and further, the cell film is easily broken by the particles of the metal compound, and it is easily difficult to obtain a high closed cell ratio. In addition, if the density is higher than 80kg/m ³ The heat conduction from the solid component such as the phenol resin increases, and therefore the heat insulating performance tends to decrease. The method for measuring the density of the phenolic resin foam is specifically described in examples described below.

The average particle diameter of the metal compound of the present embodiment is preferably 0.1 to 500. Mu.m, more preferably 0.1 to 300. Mu.m, still more preferably 1 to 200. Mu.m, most preferably 1 to 100. Mu.m. When the average particle diameter is small, particles are easily aggregated, and dispersibility is difficult to improve, so that the viscosity of the phenolic resin raw material is increased and it is difficult to uniformly mix the phenolic resin raw material into the resin. Therefore, there is a possibility that the dispersibility of the metal compound may be deteriorated. In addition, when the particle diameter is large, even if the same amount is added, the variation in the area ratio of the outermost layer increases as compared with the case where the particle diameter is small. Since the deviation increases and many metal compounds are locally present, it is difficult to sufficiently exert alkali resistance. The method for measuring the average particle diameter of the metal compound will be specifically described in examples described later.

The thermal conductivity of the phenolic resin foam of the present embodiment, as measured at 23℃is preferably 0.0260W/(mK) or less, more preferably 0.0250W/(mK) or less, still more preferably 0.0230W/(mK) or less, particularly preferably 0.0210W/(mK), and most preferably 0.0200W/(mK). The lower limit of the thermal conductivity of the phenolic resin foam measured at 23℃is not particularly limited, but is usually about 0.0150W/(mK). The method for measuring the thermal conductivity is specifically described in examples described below.

The alkali resistance of the phenolic resin foam of the present embodiment can be evaluated using, as an index, the tensile strength before the alkali acceleration test and the tensile strength of the foam after the completion of the test, which will be described later. The strength retention rate of the preferable tensile strength after the alkali acceleration test of the phenolic resin foam in the present embodiment is 30% or more, more preferably 50% or more, and still more preferably 70% or more. If the retention rate of the tensile strength is less than 30%, sufficient alkali resistance cannot be imparted, and when the resin composition is used as a wet external heat insulation method, the adhesion between the mortar and the phenolic resin foam is gradually reduced. Since the adhesive strength is lowered and the mortar may be peeled from the phenolic resin foam, the retention rate of the tensile strength is preferably 30% or more.

The phenolic resin foam of the present embodiment can be obtained by foaming and curing a "foamable phenolic resin composition" containing a "phenolic resin raw material" containing a phenolic resin, a metal compound, a surfactant, a curing catalyst for the phenolic resin, and a foaming agent, on a surface material.

The phenolic resin raw material contains a phenolic resin as a main component, water and other components as needed. The phenolic resin raw material immediately after synthesis of the phenolic resin generally contains an excess of water. Therefore, the phenolic resin raw material can be dehydrated to a predetermined moisture content and then used for the preparation of the foamable phenolic resin composition. The water content of the phenolic resin raw material is preferably 1 to 20% by mass, more preferably 1 to 13% by mass, still more preferably 2 to 10% by mass, particularly preferably 3 to 10% by mass, and most preferably 3 to 8.5% by mass, based on the mass of the phenolic resin raw material. When the water content in the phenolic resin raw material is less than 1 mass, the viscosity of the phenolic resin raw material is too high, so that the equipment is pressurized and liquid feeding failure is likely to occur. If the water content of the phenolic resin raw material is higher than 20 mass%, the viscosity of the foamable phenolic resin composition decreases, the closed cell ratio of the phenolic resin foam decreases, and the residual water content after foaming and curing increases, so that the phenolic resin foam is less likely to form closed cells, and the heat insulating property tends to decrease. Further, in order to diffuse the residual moisture by heating during the molding of the phenolic resin foam, a great amount of energy and time are required.

The phenolic resin in this embodiment is typically a polycondensate of phenol and formaldehyde. The phenolic resin can be obtained, for example, by polymerizing phenol and formaldehyde as raw materials by heating them at a temperature in the range of 40 to 100 ℃ using a base catalyst.

The amount of the metal compound to be added is preferably 15 parts by mass or less, more preferably 0.5 to 15 parts by mass, still more preferably 1 to 15 parts by mass, and most preferably 3 to 15 parts by mass, based on 100 parts by mass of the phenolic resin (phenolic resin raw material). If the amount of the metal compound to be added is less than 0.5 parts by mass, the metal compound content in the phenolic resin foam is also reduced, and a sufficient effect of addition cannot be exhibited. Therefore, the addition amount of the metal compound is not preferably less than 0.5 parts by mass. On the other hand, if the amount of the metal compound added is more than 15 parts by mass, the viscosity of the foamable phenolic resin composition after the metal compound is added becomes too high, and thus liquid feeding failure tends to occur. Therefore, the addition amount of the metal compound is not preferable to be more than 15 parts by mass. Further, since the viscosity is too high, it is difficult to obtain a foaming ratio required as a phenolic resin foam, and therefore the closed cell ratio and further the thermal conductivity of the obtained phenolic resin foam may be deteriorated.

As the surfactant, a surfactant generally used for producing a phenolic resin foam can be used, and among them, nonionic surfactants are effective. The surfactant preferably contains at least one compound selected from the group consisting of polyoxyalkylene (alkylene oxide) which is a copolymer of ethylene oxide and propylene oxide, a condensate of alkylene oxide and castor oil, a condensate of alkylene oxide and alkylphenol such as nonylphenol and dodecylphenol, a fatty acid ester such as polyoxyethylene alkyl ether having 14 to 22 carbon atoms in the alkyl ether portion, a fatty acid ester such as polyoxyethylene fatty acid ester, an organosilicon compound such as polydimethylsiloxane, and a polyol. These compounds may be used singly or in combination of two or more. The amount of the surfactant is not particularly limited, but is preferably 0.3 to 10 parts by mass per 100 parts by mass of the phenolic resin (or the phenolic resin raw material).

The curing catalyst may be an acidic curing catalyst capable of curing the phenolic resin, and is preferably an acid anhydride curing catalyst. As the acid anhydride curing catalyst, phosphoric anhydride and arylsulfonic anhydride are preferable. Examples of the arylsulfonic anhydride include toluene sulfonic acid, xylene sulfonic acid, phenol sulfonic acid, substituted phenol sulfonic acid, xylenol sulfonic acid, substituted xylenol sulfonic acid, dodecylbenzene sulfonic acid, benzene sulfonic acid, naphthalene sulfonic acid, and the like. They may be used singly or in combination. As the curing aid, resorcinol, cresol, salicyl alcohol (o-hydroxybenzyl alcohol), p-methylol phenol, and the like may be added. These curing catalysts may be diluted with a solvent such as ethylene glycol or diethylene glycol. The amount of the curing catalyst is not particularly limited, but is preferably 3 to 30 parts by mass relative to 100 parts by mass of the total amount of the phenolic resin (or the phenolic resin raw material) and the surfactant.

In this embodiment, the foaming agent may contain 1 or more selected from chlorinated, non-hydrochlorofluoroolefins, hydrocarbons and halogenated hydrocarbons.

Examples of the hydrofluoroolefins include 1-chloro-3, 3-trifluoropropene (HCFO-1233 zd), manufactured by Honeywell Japan ltd. As an E-body (HCFO-1233 zd (E)), and the product name: solution (trademark) LBA), 1, 2-trichloro-3, 3-trifluoropropene (HCFO-1213 xa), 1, 2-dichloro-3, 3-trifluoropropene (HCFO-1223 xd), 1-dichloro-3, 3-trifluoropropene (HCFO-1223 za) 1-chloro-1, 3-tetrafluoropropene (HCFO-1224 zb), 2, 3-trichloro-3-fluoropropene (HCFO-1231 xf), 2, 3-dichloro-3, 3-difluoropropene (HCFO-1232 xf), 2-chloro-1, 3-trifluoropropene (HCFO-1233 xc), and 1-chloro-1, 3-tetrafluoropropene (HCFO-1224 zb), 2, 3-trichloro-3-fluoropropene (HCFO-1231 xf) 2, 3-dichloro-3, 3-difluoropropene (HCFO-1232 xf), 2-chloro-1, 3-trifluoropropene (HCFO-1233 xc), 1-chloro-3, 3-trifluoropropene (HCFO-1233 zd), 1-chloro-2, 3-tetrafluoropropene (HCFO-1224 yd, for example, manufactured by AGC Co., ltd., product name: AMOLEA (trademark) 1224 yd) as Z-isomer (HCFO-1224 yd)), and the like, and one or a mixture of their configurational isomers, namely E-isomer or Z-isomer, are used.

Examples of the non-hydrochlorofluoroolefins include 1, 3-tetrafluoroprop-1-ene (HFO-1234 ze), for example, produced by Honeywell Japan ltd. As an E-body (HFO-1234 ze (E)), and the product name: solstine (trademark) ze), 1, 4-hexafluoro-2-butene (HFO-1336 mzz, the Chemours Company, e.g., opteon (trademark) 1100, as Z-isomer (HFO-1336 mzz (Z)), 2, 3-tetrafluoro-1-propene (HFO-1234 yf) 1, 3-pentafluoropropene (HFO-1225 zc), 1, 3-tetrafluoropropene (HFO-1234 ze), 3-trifluoropropene (HFO-1243 zf), 1,4, 5-octafluoro-2-pentene (HFO-1438 mzz), and the like, use is made of one or a mixture of their configurational isomers, namely the E or Z form.

As the hydrocarbon, for example, cyclic or chain alkane, alkene, alkyne having 3 to 7 carbon atoms can be used as the blowing agent. Specifically, the blowing agent may contain a compound such as n-butane, isobutane, cyclobutane, n-pentane, isopentane, cyclopentane, neopentane, n-hexane, isohexane, 2-dimethylbutane, 2, 3-dimethylbutane, or cyclohexane. Among them, compounds selected from pentanes such as n-pentane, isopentane, cyclopentane and neopentane, and butanes such as n-butane, isobutane and cyclobutane are suitably used. The halogenated hydrocarbon is not particularly limited, but is preferably a halogenated hydrocarbon containing at least one hydrogen element, a halogenated hydrocarbon containing no halogen atom of 2 or more, or a halogenated hydrocarbon containing no fluorine atom, more preferably isopropyl chloride, from the viewpoints of low heat conductivity, low ozone destruction coefficient, low warming coefficient, and boiling point. These foaming agents may be used alone or in combination of 2 or more.

The amount of the foaming agent added to the phenolic resin foam of the present embodiment is preferably 3.0 to 25.0 parts by mass, more preferably 5.0 to 22.5 parts by mass, still more preferably 6.5 to 22.5 parts by mass, and most preferably 7.5 to 100 parts by mass based on the total amount of the phenolic resin (or the phenolic resin raw material) and the surfactant21.5 parts by mass. If the content of the foaming agent is less than 3.0 parts by mass, it becomes very difficult to obtain a necessary expansion ratio, and a high-density foam tends to be formed. If the content of the foaming agent exceeds 25.0 parts by mass, the viscosity of the foamable phenolic resin composition decreases due to the plasticizing effect of the foaming agent, and excessive foaming occurs, so that cells of the foam tend to collapse, and the closed cell ratio tends to decrease. If the closed cell ratio is lowered, the physical properties such as long-term heat insulating property and compressive strength tend to be lowered. By the addition amount of the foaming agent being within the above-mentioned numerical range with respect to the total amount of the phenolic resin (or phenolic resin raw material) and the surfactant, a foam having 20 to 80kg/m can be formed ³ A phenolic resin foam of a density of (3).

The foamable phenolic resin composition of the present embodiment may contain additives in addition to the components described above. In the case of adding urea, as is generally known, urea may be directly added to the reaction solution at a timing in the middle or near the end of the reaction of the phenolic resin, or urea that has been methylolated in advance with a base catalyst may be mixed with the phenolic resin. Examples of the additives other than urea include phthalic acid esters which are generally used as plasticizers, and ethylene glycol and diethylene glycol which are glycols. In addition, aliphatic hydrocarbons, high-boiling alicyclic hydrocarbons, or mixtures thereof may also be used as additives. The content of the additive is preferably 0.5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the phenolic resin (or the phenolic resin raw material). If these additives are excessively added, the viscosity of the foamable phenolic resin composition may be lowered, and foam breaking may be induced during foaming and curing. On the other hand, if the additive is too small, the effect of containing the additive is not obtained. Thus, the content of the additive is more preferably 1.0 part by mass or more and 10 parts by mass or less.

The present embodiment may add the following flame retardant to the foamable phenolic resin composition as needed. The flame retardant may be selected from, for example, bromine compounds such as tetrabromobisphenol a and decabromodiphenyl ether, aromatic phosphoric acid esters, aromatic condensed phosphoric acid esters, phosphorus or phosphorus compounds such as halogenated phosphoric acid esters and red phosphorus, antimony compounds such as ammonium polyphosphate, antimony trioxide and antimony pentoxide, metal hydroxides such as aluminum hydroxide and magnesium hydroxide, and carbonates such as calcium carbonate and sodium carbonate.

The foamable phenolic resin composition can be obtained by mixing the phenolic resin raw material, the metal compound, the curing catalyst, the foaming agent and the surfactant in the above-mentioned ratio.

The phenolic resin foam can be obtained, for example, by a continuous production method comprising the steps of: a step of mixing a plurality of raw materials; a discharge step of continuously discharging the foamable phenolic resin composition onto the moving surface material; an upper surface material covering step of covering the upper surface side opposite to the surface of the discharged foamable phenolic resin composition in contact with the surface material; and a foaming/curing step of foaming and curing the foamable phenolic resin composition by heating as described later. In addition, as another embodiment, the foamable phenolic resin composition may be obtained by a batch production method in which the foamable phenolic resin composition is flowed into a mold frame covered with a surface material and a release agent, foamed, and cured by heating. The phenolic resin foam obtained by the batch production method described above may be used in the form of a slice as required.

The surface material sandwiching the phenolic resin foam is a sheet-shaped substrate, and is preferably flexible in order to prevent breakage of the surface material during production. Examples of the flexible surface material include a synthetic fiber nonwoven fabric, a synthetic fiber woven fabric, a glass fiber paper, a glass fiber woven fabric, a glass fiber nonwoven fabric, a glass fiber mixed paper, papers, a metal film, and combinations thereof. These facestocks may contain a flame retardant for imparting flame retardancy. The flame retardant may be selected from, for example, bromine compounds such as tetrabromobisphenol a and decabromodiphenyl ether, aromatic phosphoric acid esters, aromatic condensed phosphoric acid esters, phosphorus or phosphorus compounds such as halogenated phosphoric acid esters and red phosphorus, antimony compounds such as ammonium polyphosphate, antimony trioxide and antimony pentoxide, metal hydroxides such as aluminum hydroxide and magnesium hydroxide, and carbonates such as calcium carbonate and sodium carbonate. These flame retardants may be incorporated into the fibers of the facestock or may be added to binders such as acrylic, polyvinyl alcohol, vinyl acetate, epoxy, unsaturated polyester, and the like. The surface material may be surface-treated with a water repellent agent such as a fluororesin-based, silicone-based, wax emulsion-based, paraffin-based, or acrylic resin paraffin wax or an asphalt-based water repellent agent. These water repellent and water repellent agents may be used alone or applied to a facestock together with the above flame retardant.

The gas permeability of the facestock is preferably high. As such a surface material, a synthetic fiber nonwoven fabric, a glass fiber paper, a glass fiber nonwoven fabric, a paper, a pre-perforated metal film, or the like is suitably used. Of these, those having an oxygen permeability of 4.5cm as measured according to ASTM D3985-95 are particularly preferred ³ /(24h·m ² ) The gas permeable surface material described above. When a surface material having low gas permeability is used, moisture generated during curing of the phenolic resin cannot be sufficiently diffused from the foam, and moisture remains in the foam, so that a foam having low closed cell content and a large number of cells is easily formed. As a result, it is relatively difficult to maintain good heat insulating properties for a long period of time. From the viewpoints of bleeding of the foamable phenolic resin composition to the surface material during foaming and adhesion of the foamable phenolic resin composition to the surface material, when a synthetic fiber nonwoven fabric is used as the surface material, the weight per unit area is preferably 15 to 200g/m ² More preferably 15 to 150g/m ² More preferably 15 to 100g/m ² Particularly preferably 15 to 80g/m ² Most preferably 15 to 60g/m ² . In the case of using a glass fiber nonwoven fabric, the weight per unit area is preferably 30 to 600g/m ² More preferably 30 to 500g/m ² More preferably 30 to 400g/m ² Particularly preferably 30 to 350g/m ² Most preferably 30 to 300g/m ² 。

The method for producing a phenolic resin foam of the present embodiment includes a mixing step, a discharging step, a top material covering step, and a foaming and curing step of a plurality of raw materials.

In the mixing step, a metal compound is mixed with a phenolic resin raw material using a mixer. In order to improve the kneading property of the metal compound and the phenolic resin and to obtain a phenolic resin foam more efficiently and stably, the mixing step preferably includes a step of kneading the metal compound and the phenolic resin in advance before adding the foaming agent and the curing catalyst, thereby obtaining a phenolic resin composition to which the metal compound is added.

The method of adding the metal compound to the phenolic resin or the phenolic resin composition and kneading the mixture is not particularly limited, and a manual mixer, a pin mixer or the like may be used for mixing, and a twin-screw extruder, a kneader or the like may be used.

In the ejection step, the surfactant, the curing catalyst, the foaming agent, and the like are uniformly mixed by a mixer, and ejected to the mixture of the phenolic resin and the metal compound.

In order to achieve the present technology, more specifically, it is important to manufacture by the following manufacturing method. That is, the method includes a mixing step (a) of mixing a foamable phenolic resin composition containing a phenolic resin, a surfactant, a foaming agent, an acid curing agent, and a metal compound using a mixer; a spraying step (b) of spraying the mixed foamable phenolic resin composition onto the lower surface material by using 9 to 60 nozzles; a preforming step (c) of foaming and curing the foamable phenolic resin composition discharged onto the lower surface material to obtain a phenolic resin foam laminate sheet in which the surface material is disposed on at least the upper and lower surfaces of the phenolic resin foam; and a main molding step (d) of promoting foaming and curing and molding, wherein the average temperature of the center portion of the foamable phenolic resin composition discharged from the dispensing nozzle when the lower surface material in the discharging step (b) is in contact with the foamable phenolic resin composition is 40 ℃ to 55 ℃, and the atmosphere temperature in the preforming step (c) is 60 ℃ to 80 ℃ and the residence time is 5 minutes to 20 minutes. The foamable phenolic resin composition discharged from the dispensing nozzle preferably has an average temperature in the central portion of 40 ℃ to 53 ℃, an atmospheric temperature in the preforming step (c) of 70 ℃ to 80 ℃, and a residence time of 12 minutes to 20 minutes. The upper surface material covering step is included in the preforming step, and the foaming and curing step is included in the preforming step and the main forming step.

By adjusting the average temperature of the center portion of the foamable phenolic resin composition discharged from the dispensing nozzle when the lower surface material in the discharging step (b) is brought into contact with the foamable phenolic resin composition to 40 ℃ or more and 53 ℃ or less, only the foaming agent in the vicinity of the surface layer of the foamable phenolic resin composition immediately after the discharge is easily volatilized, and the cell diameter of the surface layer is reduced, so that many metal compounds can be unevenly present in the surface layer. As a result, it was found that even if the amount of the metal compound added is small, the metal compound can be contained in the surface layer, and thus alkali resistance can be sufficiently exhibited.

If the average temperature of the center portion of the foamable phenolic resin composition to be discharged is lower than 40 ℃, the time at which the foaming agent in the vicinity of the surface layer of the foamable phenolic resin composition to be discharged from each nozzle volatilizes becomes late, and thus the bubble diameter of the surface layer increases, and there is a possibility that a sufficient amount of metal compound cannot be unevenly present in the surface layer, and alkali resistance cannot be exhibited. In addition, if the average temperature of the center portion of the discharged foamable phenolic resin composition exceeds 53 ℃, the foaming agent contained in the foamable phenolic resin composition is excessively volatilized, and foaming is excessively promoted as compared with curing, so that there is a possibility that the closed cell ratio is lowered, which is not preferable. The average temperature of the center portion of the foamable phenolic resin composition to be discharged can be adjusted by adjusting the temperature, flow rate, rotation speed, and the like of the temperature control water in the mixing head dispensing portion for mixing the respective compositions. Further, the average temperature of the center of the foamable phenolic resin composition immediately after the ejection from the mixer was measured for the center of the foamable phenolic resin composition ejected from any 10 nozzles, and then the temperatures of the center of the foamable phenolic resin composition ejected from 8 nozzles from which the highest temperature and the lowest temperature were removed were averaged, thereby setting the average temperature of the center of the foamable phenolic resin composition.

In the preforming step (c), the atmosphere temperature at the time of preforming is preferably 60 ℃ to 80 ℃ and the residence time is preferably 5 minutes to 20 minutes. The atmosphere temperature and the residence time are in this range, and it is preferable that the foaming agent contained in the vicinity of the surface layer of the foamable phenolic resin is volatilized immediately after the ejection, the curing of the surface layer is promoted, the presence ratio of the metal compound in the outermost layer of the obtained phenolic resin foam can be increased, and both the high closed cell ratio and the fine cell diameter of the phenolic resin foam can be achieved.

More specifically, in the preforming step (c), the atmosphere temperature at the time of preforming is relatively high (60 ℃ or more and 80 ℃ or less), and the residence time is prolonged (5 minutes or more and 20 minutes or less), so that volatilization of the foaming agent in the vicinity of the surface layer of the foamable phenolic resin composition is promoted, and the surface layer of the foamable phenolic resin composition is rapidly cured, whereby a desired phenolic resin foam can be obtained.

The following 1 st and 2 nd ovens can be used for heating in the main molding step (d) after the preforming step (c).

In the 1 st oven, foaming and curing of the foamable phenolic resin composition are carried out at a residence time of 10 minutes to 60 minutes in an atmosphere of 60 to 110 ℃. In the 1 st oven, for example, an endless steel belt type double conveyor or a slat type double conveyor is used. In the 1 st oven, the uncured foam may be formed into a plate shape and cured to obtain a partially cured foam. In the 1 st oven, the temperature may be not uniform throughout the entire region, and a plurality of temperature regions may be provided.

The 2 nd oven can promote curing at 60 minutes to 240 minutes residence time under an atmosphere of 70 to 120 ℃. The 2 nd oven preferably post-cures the phenolic resin foam partially cured in the 1 st oven. The partially cured foam sheets may be overlapped at intervals using spacers or trays. If the temperature in the 2 nd oven is too high, the pressure of the foaming agent in the cells of the foam becomes too high, and thus, there is a possibility that foam breaking may be induced. Conversely, if the temperature in the 2 nd oven is too low, it may take too much time to promote the reaction of the phenolic resin and volatilize the excess moisture in the foam. Whereby the preferred atmosphere temperature in the 2 nd oven is 80-110 c.

The method of producing the phenolic resin foam of the present embodiment is not limited to the above method.

As described above, according to the production method of the present embodiment, a phenolic resin foam having excellent alkali resistance and further excellent heat insulating properties can be provided.

Examples

The present invention will be described more specifically below based on examples and comparative examples. However, the present invention is not limited to the following examples.

The compositions, structures and properties of the phenolic resins and phenolic resin foams in examples and comparative examples were measured and evaluated as follows.

(closed cell Rate)

The closed cell content of the phenolic resin foam was measured according to the ASTM-D-2856-94 (1998) A method as follows.

That is, a cubic test piece of about 25mm square was cut from the center portion in the thickness direction of the phenolic resin foam. When the foam was thin and a test piece having a uniform thickness of 25mm could not be obtained, the surface of the cut cubic test piece having a square of about 25mm was sliced by about 1mm, and a test piece having a uniform thickness was produced. The length of each side was measured by a vernier caliper, and the apparent volume (V1: cm) was measured ³ ) And the mass (W: significant digit 4 digits, g). Next, using a dry automatic densitometer (trade name "Accoupyc II1340" manufactured by Shimadzu corporation), the volume of the closed space (V2: cm) of the test piece was measured according to the method described in the A method of ASTM-D-2856 ³ ). The bubble diameter (t: cm) was measured by a measurement method of the average bubble diameter described later. The surface area of the test piece (A: cm) was calculated from the measured lengths of the sides ³ ). Substituting the obtained t and a into the formula: VA= (A×t)/1.14, and the open pore volume (VA: cm) of the cut bubble on the surface of the test piece was calculated ³ ). In addition, the density of the solid phenolic resin was set to 1.3g/cm ³ Using the formula: VS=mass of test piece (W)/1.3 the volume of the solid portion constituting the bubble wall contained in the test piece (VS: cm ³ )。

The closed porosity was calculated by the following formula (1).

Closed cell ratio (%) = [ (V2-VS)/(V1-VA-VS) ]x100 (1)

The closed cell ratio was measured for 6 foams obtained under the same production conditions, and the average value of the closed cell ratios was set as a representative value of the foams obtained under the production conditions.

(measurement of average bubble diameter)

The average cell diameter of the center layer and the portion 5mm in the thickness direction from the outermost layer of the phenolic resin foam can be obtained by the following method. The average cell diameter of the center layer was measured, and the phenolic resin foam was cut parallel to the front and rear surfaces to obtain a substantially center portion of the phenolic resin foam. The average bubble diameter of a cross section cut parallel to the outermost layer at a position 5mm in the thickness direction from the outermost layer was measured, and after a portion 5mm below the outermost layer in the thickness direction from one side in the thickness direction of the phenolic resin foam was cut parallel to the front and back surfaces, only the surface of the outermost layer in the thickness direction that did not include the phenolic resin foam was subjected to the measurement. Specifically, a photograph was taken of the cut surface of the test piece enlarged 50 times, and 4 straight lines corresponding to a length of 2000 μm in an actual foam cross section were drawn while avoiding voids in the obtained photograph. The number of bubbles crossing each straight line was counted, and a value obtained by dividing 2000 μm by the number of bubbles was set as the bubble diameter obtained for each straight line. Similarly, after a portion 5mm from the outermost layer on the opposite side was cut parallel to the front and rear surfaces, the bubble diameter was determined in the same manner as described above. The average value was calculated from the obtained bubble diameters at 8 points, and the average bubble diameter (t: cm) of the phenolic resin foam was set. The voids refer to bubbles having a bubble diameter corresponding to a substantially circular diameter of 1.5cm or more on the photograph enlarged to 50 times.

(foam Density)

The foam density of the phenolic resin foam was measured in accordance with JIS-K-7222. A20 cm square plate cut from the obtained phenolic resin foam was used as a sample. The surface material such as the surface material and the wallboard material was removed from the sample, and the mass and apparent volume of the foam sample remaining were measured, and the foam density was determined from the values thereof.

(calculation of the ratio of the Metal Compound present in the foam)

The ratio of the metal compound present in the foam was determined by mapping the metal element of the metal compound using the μ -XRF method, and analyzing the obtained mapped image, thereby obtaining the area ratio of the metal element, which was defined as the ratio of the metal compound present.

In the case of a face material to which a phenolic resin foam is attached, a 3-point scanning range is arbitrarily selected in the outermost layer in the thickness direction after the face material is peeled off. The sample was measured using mu-XRF (EDAX OrbisPC, manufactured by AMETEC Co., ltd.) under conditions of an X-ray tube Rh, a tube voltage of 50kV, an automatic tube current CPS, a scanning area of 20.08 mm. Times.12.4 mm, an X-axis measurement interval of 78. Mu.m, a Y-axis measurement interval of 62. Mu.m, an X-ray beam diameter of 30. Mu.m, and a measurement time of 100msec per 1 point. The image analysis was performed on the intensity-mapped image of the metal element obtained by measurement using image analysis software ImageJ (manufactured by NIH). The resulting image is first read in and converted to a gray scale (monochrome image). Then, the image was 2-valued (background black, metal element white). The threshold value for 2-valued is a value using the move method. The area ratio (%) of the white portion was calculated using Analyze Particles on the obtained 2-valued image, and the average value of the obtained 3 points was obtained. The area ratio of the metal element is set as the presence ratio of the metal compound.

In the calculation of the area ratio of the center layer of the phenolic resin foam, the center portion in the thickness direction of the phenolic resin foam was sliced to form a cross section, and 3 points were arbitrarily selected for measurement. The average value at 3 points was calculated and used as the presence ratio of the metal compound in the center layer.

(average particle diameter)

The average particle diameter of the metal compound was determined under the following conditions.

The particle size distribution was measured by using a particle size distribution measuring apparatus (Microtrac MT3300EXII-SDC, manufactured by Japanese machine Co., ltd.). The solvent was water, and the metal compound was added dropwise so as to form a proper concentration. The laser beam of 780nm wavelength was irradiated as a light source at an output power of 3mW by using a transmission method. The shape was set to be non-spherical, and the measurement time was set to 30 seconds for 2 measurements. The volume average diameter obtained as a result was set to the average particle diameter of the metal compound.

(coefficient of thermal conductivity)

According to JIS A1412-2: 1999, the initial thermal conductivity of phenolic resin foam at 23℃was measured by the following method.

First, the phenolic resin foam was cut into a square of 600 mm. The test piece obtained by cutting was placed in an atmosphere having a humidity of 50.+ -. 2% at 23.+ -. 1 ℃ and the change in mass with time was measured every 24 hours. The state of the test piece was adjusted until the mass change rate after 24 hours was 0.2 mass% or less. The test piece in the adjusted state was peeled off the surface material so as not to damage the foam, and then introduced into a thermal conductivity measuring device placed under the same environment.

The thermal conductivity was measured using a 1-piece test body and a measurement device of a symmetrical structure (trade name "HC-074/600" by Ying Hongjing Co., ltd.). The thermal conductivity under an environment of 23℃was measured at 13℃for the low temperature plate and 33℃for the high temperature plate.

(alkali resistance test)

In this embodiment, as a test for evaluating alkali resistance, the following method was used.

That is, a foam having an arbitrary thickness was cut into a size of 50mm (vertical) ×50mm (horizontal), and a foam having a surface material at the outermost layer peeled off was prepared. The tensile strength of the test piece at this time was measured and set to the initial tensile strength Ha (kPa). After mortar (weber company: therapus ultra) and water were compounded at a mass ratio of 1:0.27, the mixture was stirred at 500rpm for 4 minutes using a three-in-one motor (HEIDON company BL 1200). The stirred mortar was applied to the outermost layer of the foam from which the facestock was peeled prepared as described above to form a thickness of 7mm, and cured for 7 days at 23℃under 50% RH. The cured test body was allowed to stand at 70℃under 95% RH for 14 days, and then at 23℃under 50% RH for 7 days. The tensile strength of the test piece after the standing was measured and set as the tensile strength Hb (kPa) after the alkali resistance test. The strength maintenance ratio of the tensile strength was calculated by the following formula (2).

Tensile strength maintenance ratio (%) =100×hb/Ha (2)

The tensile test was performed as follows. The jig of 50mm in width, 50mm in length and 2mm in thickness made of stainless steel was bonded to both upper and lower surfaces (surfaces of mortar applied when mortar was applied) of the test body in the thickness direction by an adhesive (Konishi Bond Quick 5), and left to stand at room temperature for 24 hours, and then mounted on a strength tester (Shimadzu corporation, AG-Xplus). The maximum load L (N) was determined by conducting a tensile test at a tensile speed of 3 mm/min. The tensile strength was calculated by the following formula (3).

Tensile strength (kPa) =l (N)/area (m) of the outermost surface of the test body ² )(3)

(viscosity of phenolic resin or phenolic resin raw material)

The rotational speed was set so that the torque value was 10% or more by using a rotational viscometer (model RE-85R, manufactured by DONGCHINESE CORPORATION, rotor portion: 3 DEG X R14), and the value of the viscosity after 3 minutes of stabilization at 40℃was set as a measurement value.

(Synthesis of phenolic resin raw Material)

To the reactor were charged 3500kg of a 52 mass% aqueous formaldehyde solution and 2510kg of 99 mass% phenol. The reaction solution in the reactor was stirred by a propeller-type stirrer, and the temperature of the reaction solution was adjusted to 40℃by a temperature regulator. Then, 50 mass% aqueous sodium hydroxide solution was added until the pH of the reaction solution became 8.7. The reaction solution was heated to 85℃over 1.5 hours to a viscosity of 30 centistokes (= 30×10) at Ostwald ^-6 m ² Measured value at 25 ℃ per second), the reaction solution was cooled, and 400kg of urea was added. The reaction solution was then cooled to 30 ℃, and a 50 mass% aqueous solution of p-toluenesulfonic acid monohydrate was added until pH was 6.4. And concentrating the obtained reaction liquid by using a thin film evaporator to obtain a phenolic resin raw material containing phenolic resin. The water content of the obtained phenolic resin raw material was 2.4% by mass, and the viscosity was 8800 mPas.

Example 1

10 parts by mass (average particle diameter: 60 μm) of calcium sulfate as a metal compound was added to 100 parts by mass of a phenolic resin raw material by a twin screw extruder (manufactured by TECHNOVEL CORPORATION), to obtain a mixture of the phenolic resin raw material and the metal compound. 2.0 parts by mass of an ethylene oxide-propylene oxide block copolymer (manufactured by BASF, "Pluronic F-127") as a surfactant, 6.3 parts by mass of a foaming agent (n-pentane: nP), and 10 parts by mass of a mixture of 80% by mass of xylenesulfonic acid and 20% by mass of diethylene glycol as a catalyst were added to a phenolic resin raw material to which a metal compound was added, and the obtained foamable phenolic resin composition was dispensed by a multiport dispensing tube, and then supplied to a movable lower surface material. The mixer (mixer) used was a mixer disclosed in Japanese patent laid-open No. 10-225993. That is, a mixer is used in which a phenolic resin composition containing a solid foam nucleating agent and an introduction port for the foaming agent are provided on the upper side of the mixer, and the introduction port for the acidic curing agent is provided on the side near the center of the stirring section where the rotor is stirring. The stirring section is then connected to a nozzle for ejecting the foamable phenolic resin composition. That is, the mixer is constituted by a mixing section (front stage) up to the acid curing agent inlet, a mixing section (rear stage) from the acid curing agent inlet to the stirring end section, and a distributing section from the stirring end section to the nozzle. The dispensing section has a plurality of nozzles at the tip end, and is designed so as to uniformly dispense the foamable phenolic resin composition to be mixed. Further, the distribution portion has a jacket structure, and the temperature of the temperature-adjusting water in the mixing head distribution portion can be set to 26 ℃ by sufficiently exchanging heat with the temperature-adjusting water. Further, a thermocouple was provided at the ejection port of the multiport dispensing tube so that the average temperature of the center portion of the foamable phenolic resin composition could be detected. The rotational speed of the mixing head was set at 600rpm. The mixture exiting the mixer was sent to a preheated oven at 70 ℃ with the nonwoven held in place and left for 12 minutes. The average temperature of the center portion of the foamable phenolic resin immediately after the ejection from the mixer was 45 ℃. Then, the resultant was sent to a 1 st oven at 88℃and cured at a residence time of 40 minutes, and cured (cure) at a 2 nd oven at 110℃for 2 hours, to obtain a phenolic resin foam of example 1.

Example 2

A phenolic resin foam of example 2 was obtained in the same manner as in example 1 except that the rotational speed of the mixing head was changed to 350rpm, and the average temperature of the center portion of the foamable phenolic resin immediately after discharge from the mixer was set to 40 ℃.

Example 3

A phenolic resin foam of example 3 was obtained in the same manner as in example 1 except that the rotational speed of the mixing head was changed to 950rpm, and the average temperature of the center portion of the foamable phenolic resin immediately after discharge from the mixer was 53 ℃.

Example 4

A phenolic resin foam of example 4 was obtained in the same manner as in example 2 except that the amount of calcium sulfate added was 0.8 part by mass.

Example 5

A phenolic resin foam of example 5 was obtained in the same manner as in example 3 except that the amount of calcium sulfate added was 15 parts by mass.

Example 6

A phenolic resin foam of example 6 was obtained in the same manner as in example 5, except that the oven temperature in the preforming step was 80 ℃ and the residence time was 20 minutes.

Example 7

A phenolic resin foam of example 7 was obtained in the same manner as in example 1 except that the metal compound was changed to magnesium sulfate.

Example 8

A phenolic resin foam of example 8 was obtained in the same manner as in example 1 except that the metal compound was changed to iron (II) sulfate heptahydrate.

Example 9

A phenolic resin foam of example 9 was obtained in the same manner as in example 1 except that the metal compound was changed to potassium sulfate.

Example 10

A phenolic resin foam of example 10 was obtained in the same manner as in example 6 except that the metal compound was calcium carbonate and the amount thereof added was changed to 1 part by mass.

Comparative example 1

A phenolic resin foam of comparative example 1 was obtained in the same manner as in example 1, except that calcium sulfate was not added as the metal compound.

Comparative example 2

A phenolic resin foam of comparative example 2 was obtained in the same manner as in example 1, except that the amount of calcium sulfate added as the metal compound was 0.8 part by mass, the rotational speed of the mixing head was 350rpm, and the temperature of the temperature-controlled water in the mixing head distribution portion was changed to 22 ℃, whereby the average temperature in the central portion of the foamable phenolic resin immediately after discharge from the mixer was 38 ℃.

Comparative example 3

A phenolic resin foam of comparative example 3 was obtained in the same manner as in example 6 except that the rotational speed of the mixing head was changed to 950rpm, and the temperature of the temperature-regulated water in the mixing head distribution portion was changed to 28 ℃, whereby the average temperature of the central portion of the foamable phenolic resin immediately after being discharged from the mixer was 57 ℃.

The foregoing measurement and evaluation tests were performed for examples 1 to 10 and comparative examples 1 to 3. The measurement results and the evaluation results are shown in tables 1 and 2.

TABLE 1

TABLE 2

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Claims

1. A phenolic resin foam satisfying the following (1), (2) and (3), having a closed cell content of 80% or more and a foam density of 20 to 80kg/m ³ ，

(1) The metal compound in the outermost layer of the phenolic resin foam is present in a ratio of 0.5 to 25.0%,

(2) The metal compound in the center layer of the phenolic resin foam is present in a ratio of 0.5 to 15.0%,

2. The phenolic resin foam of claim 1, wherein the thermal conductivity at 23 ℃ is 0.0260W/(m-K) or less.

3. The phenolic resin foam of claim 1 or 2, wherein the phenolic resin foam has a greater presence ratio of metal compounds at the outermost layer than at the central layer of the phenolic resin foam.

4. The phenolic resin foam of any one of claims 1 to 3, wherein the metal compound is: the metal of the metal compound is at least one metal compound selected from the group consisting of calcium, magnesium, zinc, barium, aluminum, iron, sodium, and potassium, and is combined with at least one metal selected from the group consisting of oxides, chlorides, sulfates, and carbonates.

5. The phenolic resin foam of any one of claims 1 to 4, wherein the strength retention of tensile strength after alkali resistance test is 30% or more.