TW202307101A - Phenolic resin foam with an isolated air bubbling rate of 80% or more and a foam density of 20-80 kg/m3 - Google Patents

Abstract

The present invention relates to a phenolic resin foam, which satisfies the following conditions of (1), (2) and (3), and the isolated air bubbling rate is 80% or more and the foam density is 20-80 kg/m3. (1) The abundance ratio of a metal compound in the outermost layer of the phenolic resin foam is from 0.5 to 25.0%. (2) The abundance ratio of a metal compound in the central layer of the phenolic resin foam is from 0.5 to 15.0%. (3) The average bubble diameter of the section obtained by horizontal cutting at a position 5 mm from the outermost layer of the phenolic resin foam in the width direction is 50~120 [mu]m.

Description

Phenolic resin foam

The present invention relates to a phenolic resin foam which has excellent alkali resistance and is used as a building heat insulating material applicable to concrete pouring processes such as wet external heat insulation processes.

Previously, glass wool or foamed resin moldings have been widely used as heat insulating materials for buildings. As the external heat insulation process, there are known two types: dry external heat insulation process and wet external heat insulation process. Inexpensive glass wool is mainly used in dry external heat insulation process. However, when glass wool contains moisture in the wall and becomes heavy, it cannot maintain its shape and falls to the lower side of the wall. It is difficult to maintain its shape for a long time, and there is a problem that the heat insulation effect will be significantly reduced in the long run.

On the other hand, as a wet-type external heat insulation process, Patent Document 1 discloses a wet-type external heat-insulation process in which a mortar layer is provided on a heat insulation board including a foamed resin molded body and glass fiber net, and set mortar on the surface.

In the wet-type external heat insulation process of patent document 1, a glass fiber mesh is used as the mesh provided with the mortar layer on the heat insulation material. By configuring the glass fiber mesh, it is possible to prevent the thermal insulation material or the mortar layer on it from peeling off. However, there are cases where the strength of the glass fiber mesh itself is insufficient, or the strength of the glass fiber mesh is lowered due to the alkali component in the mortar, and there is a problem that the mortar layer will peel off in the long run.

Phenolic resin foam is used as a thermal insulation material for construction because of its flame retardancy and long-term maintenance of thermal insulation performance. However, the phenolic resin foam preferably has higher alkali resistance under severe conditions of high alkali concentration and high temperature and humidity. Under such conditions, when the mortar is directly laminated on the phenol resin foam, there is a risk that the mortar will fall off after construction due to the decrease in the strength of the phenol resin foam itself.

As another method for solving the alkali-induced deterioration of the phenol resin foam, a method of reducing the water absorption rate of the foam and making it difficult for the alkali component to penetrate into the foam is conceivable. Patent Document 2 discloses a method of reducing water absorption by adding a specific metal salt to a phenol resin foam. prior art literature patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2007-231723 Patent Document 2: Japanese Patent Application Laid-Open No. 2007-131859

[Problem to be solved by the invention]

In Patent Document 2, calcium carbonate is disclosed as a metal salt to be added to the phenol resin foam, but the presence ratio of calcium carbonate in the surface layer of the phenol resin foam is insufficient, so there is a problem that cannot sufficiently suppress the formation of alkali caused by alkali. The problem of deterioration.

Therefore, the object of this invention is to provide the phenol resin foam which improved the alkali resistance of the surface layer part of a phenol resin foam, and was excellent in heat insulation. [Technical means to solve the problem]

The inventors of the present invention have made intensive research to achieve the above object, and found a method by adding a specific metal compound to the phenolic resin, especially increasing the content of the metal compound in the outermost layer that is in contact with the alkali. The present invention has been accomplished by improving the alkali resistance of the conventional phenolic resin foam while maintaining excellent thermal insulation performance. The present invention implemented to solve the above-mentioned problems is as follows.

[1] A phenolic resin foam satisfying the following (1), (2) and (3), having a closed cell ratio of 80% or more and a foam density of 20 to 80 kg/m ³ . (1) The abundance ratio of the metal compound in the outermost layer of the phenol resin foam is 0.5 to 25.0%. (2) The abundance ratio of the metal compound in the center layer of the phenol resin foam is 0.5 to 15.0%. (3) At a position 5 mm away from the outermost layer of the phenolic resin foam in the thickness direction, the average cell diameter of a section cut parallel to the outermost layer is 50 to 120 μm. [2] The phenolic resin foam as described in [1], wherein the thermal conductivity at 23°C is 0.0260 W/(m·K) or less. [3] The phenol resin foam as described in [1] or [2], wherein the ratio of the metal compound in the outermost layer of the phenol resin foam is greater than that of the metal compound in the center layer of the phenol resin foam the existence ratio. [4] The phenolic resin foam according to any one of [1] to [3], wherein the metal of the metal compound is selected from the group consisting of calcium, magnesium, zinc, barium, aluminum, iron, sodium, and potassium At least one of the above-mentioned metal compounds is a combination of one or more metal compounds containing the above-mentioned metal and at least one selected from the group of oxides, chlorides, sulfates, and carbonates. [5] The phenolic resin foam according to any one of [1] to [4], wherein the tensile strength retention rate after the alkali resistance test is 30% or more. [Effect of Invention]

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

Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. In addition, this invention is not limited to the following embodiment.

The metal element of the metal compound in this embodiment is preferably one selected from the group consisting of calcium, magnesium, zinc, barium, aluminum, iron, sodium, and potassium. Also, the metal compound is preferably selected from the group of oxides, chlorides, sulfates, and carbonates of the above-mentioned metals. Among them, calcium sulfate, magnesium sulfate, iron sulfate, sodium sulfate, and potassium sulfate are more preferable, among which calcium sulfate is the most preferable. These metal compounds may be used alone or in combination. The identification of the metal compound contained in the phenolic resin foam can be identified using a commonly used X-ray diffraction method (XRD).

In this embodiment, the ratio of metal compound in the outermost layer of the phenolic resin foam is in the range of 0.5 to 25.0%, preferably 0.5 to 20.0%, more preferably 1.0 to 20.0%, and still more preferably 3.0%. ~20.0%, the best is 5.0~20.0%. By allowing the metal compound to exist in the outermost layer in this range, sufficient alkali resistance can be expressed even if the amount added is small. When the ratio of the metal compound is less than 0.5%, there is not enough metal compound in the outermost layer, so the effect of alkali resistance cannot be exerted. In addition, when the ratio of the metal compound is higher than 25.0%, there is a possibility that the thermal insulation performance may be deteriorated due to the heat conduction of the metal compound, and the bubble film may be broken starting from the metal compound, and the independent cell rate may decrease, so it is not good. . Here, the outermost layer of the phenolic resin foam refers to the outermost layer of the surface perpendicular to the thickness direction of the phenolic resin foam, and the ratio of the metal compound is obtained by evaluating each of the upper and lower surfaces and averaging them. . The method of measuring the abundance ratio of the metal compound in the outermost layer will be specifically described in Examples described later.

In the phenolic resin foam in this embodiment, the ratio of the metal compound in the center layer is in the range of 0.5 to 15.0%, preferably in the range of 0.5 to 10.0%, more preferably in the range of 3.0 to 10.0%, most preferably 5.0% ~10.0% range. When the ratio of the metal compound contained in the center layer exceeds 15.0%, the bubble film is likely to break starting from the metal compound, so the closed cell rate and thermal conductivity of the phenolic resin foam tend to deteriorate. Therefore, it is unfavorable that the abundance ratio of the metal compound contained in the center layer exceeds 15.0%. Also, when the ratio of the metal compound contained in the center layer is less than 0.5%, the ratio of the metal compound in the outermost layer of the phenolic resin foam naturally decreases, making it difficult to obtain the effect of adding the metal compound. Therefore, it is unfavorable that the abundance ratio of the metal compound contained in the center layer is less than 0.5%. Here, the term "center layer" refers to a layer located at the center in the thickness direction of the phenol resin foam and parallel to the outermost layer. The method for measuring the abundance ratio of the metal compound in the center layer will be described in detail in the Examples below.

In the phenol resin foam in this embodiment, the abundance ratio of the metal compound in the outermost layer of the phenol resin foam is preferably larger than the abundance ratio of the metal compound in the center layer. By satisfying this condition, the metal compound is efficiently distributed in the thickness direction of the phenolic resin foam, so that it is easy to maintain excellent heat insulation performance, while taking into account the alkali resistance of the phenolic resin foam, and the effect becomes More prominent, so better. The value obtained by dividing the ratio of the metal compound in the outermost layer of the phenolic resin foam by the ratio of the metal compound in the center layer is preferably greater than 1.00, more preferably 1.10 or more, further preferably 1.30 or more, particularly preferably Above 1.60, preferably above 1.70.

In the phenolic resin foam in this embodiment, at a position 5 mm from the outermost layer of the phenolic resin foam (after the surface material is peeled off when the surface material is included) in the thickness direction, parallel to the outermost layer The average bubble diameter of the section obtained by cutting is in the range of 50-120 μm, preferably 50-110 μm, more preferably 70-110 μm, further preferably 70-100 μm, most preferably 80-100 μm scope. If the average cell diameter at the position falls within this range, the content of the metal compound in the phenol resin foam on the surface layer side relative to the position can be increased accordingly. Therefore, it turns out that the surface layer side of a phenol resin foam can exhibit alkali resistance. Furthermore, when the average cell diameter is less than 50 μm, the density of the outermost layer is too high, so the foamable phenolic resin composition is likely to ooze out from the surface of the surface material, which may contaminate the device when the foam is formed. Also, when the average cell diameter exceeds 120 μm, the ratio of metal compounds in the outermost layer decreases, and alkali resistance may not be exhibited. Therefore, when the average cell diameter exceeds 120 μm, it is unfavorable.

The closed cell rate of the phenolic resin foam in this embodiment is 80% or more, preferably 85% or more, more preferably 90% or more, most preferably 95% or more. When the independent cell rate is too low, the thermal conductivity becomes higher because the blowing agent contained in the bubbles is easily replaced with air, or the thermal conductivity deteriorates faster after a long time, or the compressive strength becomes lower. low tendency. The method for measuring the independent cell ratio will be described in detail in Examples described later.

The density of the phenol resin foam in this embodiment is 20 kg/m ³ to 80 kg/m ³ , preferably 25 kg/m ³ to 55 kg/m ³ , more preferably 27 kg/m ³ to 45 kg/m ³ , preferably 27 kg/m ³ to 40 kg/m ³ . When the density is lower than 20 kg/m ³ , the strength is low, and the foam is easily damaged during handling or construction. Also, when the density is low, the cell film tends to become thinner. When the bubble film is thin, the blowing agent in the foam is easily replaced with air, and the particles of the metal compound may easily break the bubble film, making it difficult to obtain a high independent cell rate. Also, when the density is higher than 80 kg/m ³ , the heat conduction of the solid from the solid content represented by the phenolic resin becomes large, so the thermal insulation performance tends to decrease. The method for measuring the density of the phenol resin foam will be described in detail in the Examples below.

The average particle size of the metal compound in this embodiment is preferably 0.1-500 μm, more preferably 0.1-300 μm, further preferably 1-200 μm, most preferably 1-100 μm. When the average particle size is small, it is difficult to improve the dispersibility because the particles are easily aggregated with each other, so the viscosity of the phenol resin raw material becomes high, and it is difficult to mix uniformly in the resin. For this reason, there exists a possibility that the dispersibility of a metal compound may deteriorate. Also, when the particle size is large, even if the added amount is the same, the variation in the area ratio of the outermost layer becomes larger than when the particle size is small. Since the variation becomes large, a lot of metal compounds locally exist, so it is difficult to fully exert the alkali resistance. The method for measuring the average particle diameter of the metal compound will be described in detail in Examples described later.

The thermal conductivity of the phenolic resin foam in this embodiment measured at 23°C is preferably below 0.0260 W/(m·K), more preferably below 0.0250 W/(m·K). The best is below 0.0230 W/(m・K), the best is 0.0210 W/(m・K), and the best is 0.0200 W/(m・K). The lower limit of the thermal conductivity of the phenolic resin foam measured at 23°C is not particularly limited, and is usually around 0.0150 W/(m·K). The method for measuring the thermal conductivity will be described in detail in the Examples below.

The alkali resistance of the phenol resin foam in this embodiment can be evaluated by using the tensile strength before the alkali accelerated test described later and the tensile strength of the foam after the test as indicators. The strength retention rate of the tensile strength of the phenol resin foam in this embodiment after the alkali accelerated test is preferably at least 30%, more preferably at least 50%, and still more preferably at least 70%. When the retention rate of the tensile strength is less than 30%, sufficient alkali resistance cannot be imparted, and when used in a wet-type external heat insulation process, the adhesive force between the mortar and the phenolic resin foam gradually decreases. Since the adhesive force is reduced, there is a possibility that the mortar will be peeled off from the phenolic resin foam, so the retention rate of tensile strength is preferably 30% or more.

The phenolic resin foam of this embodiment can be obtained by foaming and hardening a "foamable phenolic resin composition" on a surface material. The above-mentioned foamable phenolic resin composition contains: Raw materials”, metal compounds, surfactants, hardening catalysts for phenolic resins, and foaming agents.

The phenolic resin raw material contains phenolic resin as main components, water, and other components as the case may be. Phenolic resin raw materials immediately after synthesis usually contain excess water. Therefore, the phenolic resin raw material can be used in the preparation of foamable phenolic resin composition after being dehydrated to a specific water content. The moisture content of the phenolic resin raw material is based on the mass of the phenolic resin raw material, preferably 1-20% by mass, more preferably 1-13% by mass, further preferably 2-10% by mass, particularly preferably 3-10% by mass % by mass, preferably 3 to 8.5% by mass. When the moisture content in the phenolic resin raw material is less than 1% by mass, the viscosity of the phenolic resin raw material is too high, so the pressure of the equipment becomes high, and it is easy to cause poor liquid delivery. Also, when the moisture content of the phenolic resin raw material is higher than 20% by mass, the independent cell rate of the phenolic resin foam decreases due to the decrease in the viscosity of the foamable phenolic resin composition, and the residual moisture after foaming and hardening becomes Therefore, it is difficult for the phenolic resin foam to form independent cells, and the thermal insulation property tends to decrease. Furthermore, a large amount of energy and time are required to diffuse the above-mentioned residual moisture by heating during molding of the phenolic resin foam.

The phenol resin in this embodiment is typically a polycondensate of phenol and formaldehyde. The phenolic resin can be obtained, for example, by using phenol and formaldehyde as raw materials, heating them in a temperature range of 40-100° C. with an alkali catalyst, and polymerizing them.

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, further preferably 1 to 15 parts by mass, most preferably 3 to 15 parts by mass, relative to 100 parts by mass of the phenol resin (phenolic resin raw material). 15 parts by mass. When the added amount of the metal compound is less than 0.5 parts by mass, the content of the metal compound in the phenol resin foam also decreases, and a sufficient effect of the addition cannot be exhibited. Therefore, it is unfavorable that the addition amount of a metal compound is less than 0.5 mass part. On the other hand, when the added amount of the metal compound is greater than 15 parts by mass, the viscosity of the foamable phenolic resin composition after adding the metal compound is too high, which easily causes poor liquid delivery. Therefore, when the addition amount of a metal compound exceeds 15 mass parts, it is unpreferable. Furthermore, if the viscosity is too high, it will be difficult to obtain the expansion ratio required for the phenol resin foam, so the closed cell ratio and thermal conductivity of the obtained phenol resin foam may be deteriorated.

Surfactant can be used usually in the manufacture of phenolic resin foam, among which nonionic surfactant is effective. The surfactant preferably contains at least one compound selected from the following compounds: a copolymer of ethylene oxide and propylene oxide, that is, a polyoxyalkylene group (alkylene oxide); a mixture of alkylene oxide and castor oil. Condensates; Condensates of alkylene oxide and alkylphenols such as nonylphenol and dodecylphenol; Polyoxyethylene alkyl ethers with 14-22 carbon atoms in the alkyl ether part; Polyoxyethylene fatty acid esters fatty acid esters such as dimethicone; silicone compounds such as dimethicone; and polyols. These compounds may be used alone 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 relative to 100 parts by mass of the phenol resin (or phenol resin raw material).

As the curing catalyst, any acid curing catalyst can be used as long as it can cure the phenol resin, and an acid anhydride curing catalyst is preferred. As the acid anhydride curing catalyst, phosphoric anhydride and arylsulfonic anhydride are preferred. Examples of arylsulfonic acid anhydrides include: toluenesulfonic acid or xylenesulfonic acid, phenolsulfonic acid, substituted phenolsulfonic acid, xylenolsulfonic acid, substituted xylenolsulfonic acid, dodecylbenzenesulfonic acid acid, benzenesulfonic acid, or naphthalenesulfonic acid, etc. One of these may be used, or two or more may be combined. Moreover, resorcinol, cresol, salicyl alcohol (o-hydroxybenzyl alcohol), p-hydroxymethylphenol, etc. can be added as a hardening aid. Moreover, these hardening catalysts can also be diluted with solvents, such as ethylene glycol and diethylene glycol. The amount of the curing catalyst is not particularly limited, but it is preferably 3 to 30 parts by mass relative to 100 parts by mass of the total amount of the phenol resin (or phenol resin raw material) and the surfactant.

In this embodiment, the blowing agent may contain one or more selected from chlorinated and non-chlorinated hydrofluoroolefins, hydrocarbons, and halogenated hydrocarbons.

Examples of chlorinated hydrofluoroolefins include: 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd, such as E body (HCFO-1233zd (E)), manufactured by Honeywell Japan Co., Ltd., product name: Solstice ( Trademark) LBA), 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-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), 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd), and 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd, such as Z body (HCFO- 1224yd(Z)), manufactured by AGC Co., Ltd., product name: AMOLEA (trademark) 1224yd), etc., and one or a mixture of these configurational isomers, that is, E body or Z body, can be used.

Examples of non-chlorinated hydrofluoroolefins include: 1,3,3,3-tetrafluoropropane-1-ene (HFO-1234ze, such as E body (HFO-1234ze(E)), manufactured by HoneyWell Japan Co., Ltd., product name : Solstice (trademark) ze), 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz, such as Z body (HFO-1336mzz(Z)), manufactured by Chemours Co., Ltd., Opteon (trademark) 1100), 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- For pentene (HFO-1438mzz), etc., one or a mixture of these configurational isomers, that is, E body or Z body, can be used.

Hydrocarbons such as cyclic or chain alkanes, olefins, and alkynes having 3 to 7 carbon atoms can be used as blowing agents. Specifically, the blowing agent may contain: n-butane, isobutane, cyclobutane, n-pentane, isopentane, cyclopentane, neopentane, n-hexane, isohexane, 2,2-bis Methylbutane, 2,3-dimethylbutane, cyclohexane and other compounds. Among these, compounds selected from pentanes such as n-pentane, isopentane, cyclopentane and neopentane, and butanes such as n-butane, isobutane and cyclobutane are suitably used. Halogenated hydrocarbons are not particularly limited, but from the standpoint of thermal conductivity, ozone depletion coefficient and warming coefficient, or boiling point, it is preferably a halogenated hydrocarbon containing at least one hydrogen element, and does not contain more than two kinds. A halogenated hydrocarbon containing a halogen atom, or a halogenated hydrocarbon not containing a fluorine atom, more preferably 2-chloropropane. These blowing agents may be used alone or in combination of two or more.

The amount of foaming agent added to the phenol resin foam of this embodiment is preferably 3.0 to 25.0 parts by mass, more preferably 5.0 to 22.5 parts by mass, more preferably 6.5 to 22.5 parts by mass, most preferably 7.5 to 21.5 parts by mass. When the content of the foaming agent is less than 3.0 parts by mass, it is difficult to obtain the desired expansion ratio, and a high-density foam tends to be formed. When the content of the foaming agent exceeds 25.0 parts by mass, due to the plasticizing effect of the foaming agent, the viscosity of the foamable phenolic resin composition will decrease and cause excessive foaming, so the bubbles of the foam will burst and independent cells will tendency to decrease. When the independent cell ratio decreases, physical properties such as long-term heat insulation performance and compressive strength tend to decrease. By making the amount of foaming agent added relative to the total amount of phenol resin (or phenol resin raw material) and surfactant within the above numerical range, phenol resin foaming with a density of 20-80 kg/ ^m3 can be formed body.

The foamable phenol resin composition of this embodiment may contain an additive other than the components demonstrated above. In the case of adding urea, the urea can be directly added to the reaction solution in the middle of the reaction of the phenolic resin or near the end of the reaction in a well-known manner, or the urea that has been methylolated by an alkali catalyst in advance can be mixed with the phenolic resin . As additives other than urea, for example, phthalates generally used as plasticizers, and glycols such as ethylene glycol and diethylene glycol can be used. In addition, aliphatic hydrocarbons, high-boiling alicyclic hydrocarbons, or mixtures thereof can also be used as additives. The content of the additive is preferably not less than 0.5 parts by mass and not more than 20 parts by mass relative to 100 parts by mass of the phenol resin (or phenol resin raw material). When these additives are excessively added, the viscosity of the foamable phenolic resin composition decreases, and there is a possibility that bubbles may burst during foam hardening. On the other hand, when there are too few additives, the effect of containing the additives cannot be obtained. Therefore, the content of the additive is more preferably from 1.0 to 10 parts by mass.

In this embodiment, the following flame retardants may be added to the foamable phenol resin composition as needed. The flame retardant can be selected from, for example: bromine compounds such as tetrabromobisphenol A and decabromodiphenyl ether; phosphorus or phosphorus compounds such as aromatic phosphates, aromatic condensed phosphates, halogenated phosphates, and red phosphorus; ammonium polyphosphate; Antimony compounds such as 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 said phenolic resin raw material, metal compound, hardening catalyst, foaming agent, and surfactant in the ratio mentioned above.

The phenolic resin foam can be obtained, for example, by a continuous production method, which includes: a mixing step of a plurality of raw materials; a spraying step, which continuously sprays the foamable phenolic resin composition on the moving surface material; the surface material Coating step, which also covers the surface material on the upper surface side of the sprayed foamable phenolic resin composition opposite to the surface contacting the surface material; The phenolic resin composition foams and hardens with heat. In addition, as another embodiment, it can also be implemented by the following mass production method: the above-mentioned foamable phenolic resin composition is poured into the mold frame whose inner side is coated with a surface material or a release agent, and it is foamed and heat-cured. . The phenolic resin foam obtained by the above mass production method can also be sliced and used as required.

The surface material sandwiched with phenolic resin foam is a sheet-like base material. In order to prevent the surface material from breaking during production, it is preferably flexible. Examples of flexible surface materials include: synthetic fiber non-woven fabric, synthetic fiber woven fabric, glass fiber paper, glass fiber woven fabric, glass fiber non-woven fabric, glass fiber mixed paper, paper, metal film, or combinations thereof . These face materials may also contain flame retardants to impart flame retardancy. The flame retardant can be selected from, for example: bromine compounds such as tetrabromobisphenol A and decabromodiphenyl ether; phosphorus or phosphorus compounds such as aromatic phosphates, aromatic condensed phosphates, halogenated phosphates, and red phosphorus; ammonium polyphosphate; Antimony compounds such as 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 can be kneaded in the fiber of the surface material, and can also be added to adhesives such as acrylic resin, polyvinyl alcohol, vinyl acetate, epoxy resin, and unsaturated polyester. In addition, the surface material can be treated with water-repellent agents such as fluororesin-based, silicone-based, wax-emulsion-based, paraffin-based, and acrylic-based paraffin-based water-repellent agents or asphalt-based waterproofing agents. These water-repellent agents and water-repellent treatment agents can be used alone, and can also be coated on the surface material together with the above-mentioned flame retardants.

The gas permeability of the surface material should be high. As such a surface material, synthetic fiber nonwoven fabric, glass fiber paper, glass fiber nonwoven fabric, paper, pre-perforated metal film, etc. are suitably used. Among such surface materials, the gas-permeable surface materials with an oxygen permeability rate of 4.5 cm ³ /(24h·m ² ) or higher measured according to ASTM D3985-95 are particularly preferred. In the case of using a surface material with low gas permeability, the moisture generated when the phenolic resin is hardened cannot be sufficiently diffused out of the foam, and the moisture remains in the foam, so it is easy to form independent cells with a low rate and many pores The foam. Therefore, it may be difficult to maintain good thermal insulation performance over a long period of time. From the point of view of the exudation of the foamable phenolic resin composition to the surface material during foaming, and the adhesion between the foamable phenolic resin composition and the surface material, when the surface material uses a synthetic fiber non-woven fabric, its unit The area weight is preferably 15-200 g/m ² , more preferably 15-150 g/m ² , further preferably 15-100 g/m ² , particularly preferably 15-80 g/m ² , most preferably 15-60 g/m ² . When glass fiber non-woven fabric is used, the weight per unit area is preferably 30-600 g/m ² , more preferably 30-500 g/m ² , further preferably 30-400 g/m ² , especially preferably 30-350 g/m ² , preferably 30-300 g/m ² .

The manufacturing method of the phenolic resin foam of this embodiment includes: the mixing process of several raw materials, the spraying process, the surface material coating process, and the foaming hardening process.

In the mixing step, the metal compound is mixed in the phenolic resin raw material using a mixer. In order to improve the kneadability of the metal compound and the phenol resin, and obtain the phenol resin foam more efficiently and stably, the above-mentioned mixing step preferably includes the following steps: before adding the foaming agent and the hardening catalyst, make the metal compound and the phenol resin The resin is kneaded in advance to obtain a metal compound-added phenol resin composition.

The method of adding the metal compound to the phenolic resin or the phenolic resin composition and kneading is not particularly limited, and may be mixed using a hand mixer, paddle mixer, etc., or a twin-screw extruder, kneading machine, etc. may be used.

In the spraying step, the surfactant, the hardening catalyst, and the foaming agent are uniformly mixed into the mixture of the phenolic resin and the metal compound by a mixer before spraying.

In order to realize this technology, more specifically, it is important to manufacture by the following manufacturing method. That is, the production method includes: a mixing step (a) of mixing the foamable phenolic resin composition containing a phenolic resin, a surfactant, a foaming agent, an acid hardener and a metal compound using a mixer; a spraying step ( b) using more than 9 nozzles and less than 60 nozzles to distribute and spray the mixed foamable phenolic resin composition onto the lower material; The resin composition is foamed and hardened, thereby obtaining a phenolic resin foamed volume laminate with surface materials disposed on at least the upper and lower surfaces of the phenolic resin foam; the formal forming step (d), which promotes foaming and hardening, and is formed; And in the spraying step (b), the average temperature of the central part of the foamable phenolic resin composition sprayed from the dispensing nozzle when the bottom material is in contact with the foamable phenolic resin composition is 40°C or more and 55°C or less, and the preforming step The ambient temperature in (c) is not less than 60°C and not more than 80°C, and the residence time is not less than 5 minutes and not more than 20 minutes. Preferably, the average temperature of the center of the foamable phenol resin composition ejected from the dispensing nozzle is 40°C to 53°C, the ambient temperature in the preforming step (c) is 70°C to 80°C, and the stagnant The time is not less than 12 minutes and not more than 20 minutes. Furthermore, the above-mentioned top material coating step is included in the preforming step, and the foaming and hardening step is included in the preforming step and the main forming step.

In the spraying step (b), the average temperature of the central part of the foamable phenolic resin composition sprayed from the dispensing nozzle when the bottom sheet is in contact with the foamable phenolic resin composition is adjusted to 40°C or more and 53°C or less, thereby In the foamable phenol resin composition immediately after spraying, only the blowing agent near the surface layer is easily volatilized, and the diameter of the bubbles in the surface layer becomes smaller, so that more metal compounds can be concentrated in the surface layer. As a result, it was found that the metal compound can be contained in the surface layer even if the added amount of the metal compound is small, so that alkali resistance can be sufficiently exhibited.

When the average temperature of the central portion of the foamable phenolic resin composition that is sprayed is less than 40°C, there are cases where the foaming agent near the surface of the foamable phenolic resin composition sprayed from each nozzle volatilizes Delay causes the diameter of bubbles on the surface to become larger, and there is not a sufficient amount of metal compounds in the surface layer, so that the alkali resistance cannot be exerted. Also, when the average temperature of the central portion of the sprayed foamable phenolic resin composition exceeds 53°C, the foaming agent contained in the foamable phenolic resin composition will volatilize excessively, and foaming will be more difficult than curing. Since it is promoted excessively, there exists a possibility that the independent cell rate may fall, and it is unpreferable. Furthermore, the average temperature of the central portion of the sprayed foamable phenolic resin composition can be adjusted appropriately by adjusting the tempering water temperature, flow rate, and rotational speed of the mixing head distribution portion where various compositions are mixed. Also, the average temperature of the central portion of the expandable phenol resin composition immediately after being ejected from the mixer was obtained by measuring the temperature of the central portion of the expandable phenol resin composition ejected from any 10 nozzles. After the temperature, the highest temperature and the lowest temperature were removed, and the temperatures at the center of the expandable phenolic resin composition ejected from the eight nozzles were averaged as the average temperature of the center of the expandable phenolic resin composition.

In the preforming step (c), it is preferable that the ambient temperature during preforming is not less than 60°C and not more than 80°C, and the residence time is not less than 5 minutes and not more than 20 minutes. If the ambient temperature and residence time are within this range, the blowing agent contained near the surface of the foamable phenolic resin will be volatilized immediately after spraying, and the hardening of the surface will be promoted, which will not only improve the foam quality of the obtained phenolic resin foam The existence ratio of the metal compound in the outermost layer is preferable because it can take into account the high independent cell rate of the phenolic resin foam and the miniaturization of the cell diameter.

More specifically, in the preforming step (c), by making the ambient temperature during preforming relatively high (60°C to 80°C) and prolonging the residence time (5 minutes to 20 minutes), it will promote The foaming agent near the surface of the foamable phenol resin composition volatilizes and at the same time rapidly hardens the surface of the foamable phenol resin composition, whereby a desired phenol resin foam can be obtained.

In the heating of the main forming step (d) following the preforming step (c), for example, the following first oven and second oven can be used.

In the first oven, foaming and hardening of the expandable phenolic resin composition are performed in an environment of 60 to 110° C. with a residence time of 10 minutes to 60 minutes. In the first oven, for example, an endless steel belt type double conveyor belt or a slat type double conveyor belt is used. In the first oven, the unhardened foam can be formed into a plate while hardened to obtain a partially hardened foam. In the first oven, it is not necessary to maintain a uniform temperature in the entire oven, and multiple temperature zones can also be set.

The second oven can accelerate hardening with a residence time of 60 minutes to 240 minutes in an environment of 70-120°C. The second oven is preferably one that postcures the phenol resin foam partially cured in the first oven. Partially hardened foam sheets can be stacked at regular intervals using spacers or trays. If the temperature in the second oven is too high, the pressure of the foaming agent inside the cells of the foam will be too high, which may cause the bubbles to burst. Conversely, if the temperature in the second oven is too low, it may take too much time to volatilize the remaining moisture in the foam while the reaction of the phenolic resin is proceeding. Therefore, the ambient temperature in the second oven is preferably 80-110°C.

The manufacturing method for obtaining the phenol resin foam of this embodiment is not limited to the said method.

As mentioned above, according to the manufacturing method of this embodiment, the phenol resin foam which has excellent alkali resistance and further excellent thermal insulation performance can be provided. [Example]

Hereinafter, based on an Example and a comparative example, this invention is demonstrated more concretely. However, the present invention is not limited to the following examples.

Regarding the compositions, structures, and characteristics of the phenol resins and phenol resin foams in Examples and Comparative Examples, the following items were measured and evaluated.

(Closed Cell Rate) According to ASTM-D-2856-94(1998)A method, the closed cell rate of the phenol resin foam was measured by the following method. That is, a cube test piece of about 25 mm square was cut out from the central part in the thickness direction of the phenolic resin foam. When the thickness of the foam is too thin to obtain a test piece with a uniform thickness of 25 mm, the surface of the cut-out cube test piece of about 25 mm square is cut into pieces of about 1 mm each to make a piece with a uniform thickness The test piece. Use a vernier caliper to measure the length of each side, measure the apparent volume (V1: cm ³ ) and measure the mass of the test piece (W: 4 significant digits, g). Next, using a dry automatic density meter (manufactured by Shimadzu Corporation, trade name "AccuPyc II1340"), the closed space volume (V2: cm ³ ) of the test piece was measured according to the method described in Method A of ASTM-D-2856. Moreover, the bubble diameter (t: cm) was measured according to the measuring method of the average bubble diameter mentioned later. Calculate the surface area (A: cm ³ ) of the test piece according to the measured length of each side. Substitute the obtained t and A into the formula: VA=(A×t)/1.14 to calculate the open volume (VA: cm ³ ) of the cut-off air bubbles on the surface of the test piece. Also, set the density of the solid phenolic resin to 1.3 g/cm ³ , and calculate the volume of the solid portion (VS: cm ³ ) constituting the cell walls contained in the test piece according to the formula: VS = mass of the test piece (W)/1.3. The closed cell ratio was calculated from the following formula (1). Independent cell rate (%)=[(V2－VS)/(V1－VA－VS)]×100 (1) Measure the independent cell rate for 6 foams obtained under the same manufacturing conditions, and take the average value It is a representative value of the foam obtained under the production conditions.

(Measurement of average bubble diameter) The average cell diameter of the central layer of the phenolic resin foam and the portion below 5 mm in the thickness direction from the outermost layer can be obtained by the following method. The measurement of the average cell diameter of the center layer was carried out by cutting the approximate center of the phenolic resin foam parallel to the front and back. At a position 5 mm away from the outermost layer in the thickness direction, the average cell diameter of the section obtained by cutting parallel to the outermost layer is on the side of the thickness direction of the phenolic resin foam parallel to the front and back. The distance from the outermost layer in the thickness direction is less than 5 mm, and the measurement is carried out only on the surface that does not include the outermost layer in the thickness direction of the phenolic resin foam. Specifically, the cut section of the test piece was enlarged 50 times to take a picture, and four straight lines with a length equivalent to 2,000 μm in the actual foam cross section were drawn avoiding voids on the obtained picture. The number of bubbles crossed by each straight line was counted, and the value obtained by dividing 2,000 μm by the number of bubbles was taken as the bubble diameter obtained from each straight line. Similarly, after cutting the part below 5 mm from the outermost layer on the side opposite to the above in parallel to the front and back, the cell diameter was obtained in the same manner as above. The average value was calculated from the obtained 8-point cell diameter, and it was set as the average cell diameter (t: cm) of the phenol resin foam. In addition, the so-called pores refer to bubbles having a bubble diameter corresponding to a substantially circular diameter of 1.5 cm or more on the above-mentioned photograph enlarged to 50 times.

(foam density) The expansion density of the phenol resin foam was measured in accordance with JIS-K-7222. A 20 cm square plate cut out from the obtained phenol resin foam was used as a sample. Remove surface materials such as surface materials and wall materials from the sample, measure the mass and apparent volume of the remaining foam sample, and calculate the foam density based on these values.

(Calculation of Existing Ratio of Metal Compound in Foam) The existence ratio of the metal compound in the foam is determined by mapping the metal element of the metal compound using the μ-XRF method, and analyzing the obtained mapping image to obtain the area ratio of the metal element and set it as is the ratio of metal compounds present.

In the case of a surface material with a phenolic resin foam attached, after peeling off the surface material, arbitrarily select a 3-point scanning range on the outermost layer in the thickness direction. Using μ-XRF (AMETEC company, device EDAX OrbisPC), with X-ray tube Rh, tube voltage 50 kV, tube current automatic CPS (Control and Protective Switch, control and protection switch), scanning area 20.08 mm×12.4 mm , The measurement interval in the X-axis direction is 78 μm, the measurement interval in the Y-axis direction is 62 μm, the X-ray beam diameter is 30 μm, and the measurement time for each point is 100 msec to measure the sample. Image analysis was performed on the intensity map image of the metal elements obtained by the measurement using image analysis software ImageJ (manufactured by NIH). First, the resulting image is read and converted to grayscale (monochrome image). Next, binarize the image (the background is black, and the metal elements are white). Furthermore, the selection force difference method is used to obtain the threshold value of binarization. For the obtained binarized image, the area ratio (%) of the white portion was calculated using Analyze Particles, and the average value of the obtained three points was calculated. The area ratio of the metal element was defined as the abundance ratio of the metal compound.

In addition, in the calculation of the area ratio of the center layer of the phenol resin foam, the center part of the thickness direction of the phenol resin foam was sliced to obtain a cross section, and three points were arbitrarily selected and measured. The average value of three points was calculated as the abundance ratio of the metal compound in the center layer.

(The average particle size) The average particle size of the metal compound was obtained under the following conditions. Measurement was performed using a particle size distribution analyzer (manufactured by Nikkiso Co., Ltd., Microtrac MT3300EXII-SDC). Water is used as solvent, and metal compound is added dropwise to make it reach an appropriate concentration. Using the transmission method, laser light with a wavelength of 780 nm as a light source was irradiated with an output of 3 mW. The shape was made aspherical, the measurement time was made 30 seconds, and the measurement was performed twice. The resulting volume average diameter was defined as the average particle diameter of the metal compound.

(Thermal conductivity) Based on JIS A 1412-2:1999, the initial thermal conductivity of the phenol resin foam in the environment of 23 degreeC was measured by the following method. First, the phenolic resin foam was cut into 600 mm squares. Put the cut-off test pieces into an environment at 23±1°C and 50±2% humidity, and measure the change of mass over time every 24 hours. Adjust the state of the test piece until the mass change rate after 24 hours reaches 0.2% by mass or less. After the test piece in the conditioned state is peeled off the surface material so that the foam is not damaged, it is introduced into a thermal conductivity measurement device placed in the same environment.

The measurement of the thermal conductivity was carried out using a measuring device with a symmetrical configuration (Heihong Seiki Co., Ltd., trade name "HC-074/600") using one test piece. The thermal conductivity under the environment of 23°C is measured under the conditions of 13°C on the low temperature plate and 33°C on the high temperature plate.

(alkali resistance test) In this embodiment, the test for evaluating alkali resistance was performed using the following method. That is, the following foam is prepared, the foam of arbitrary thickness is cut into a size of 50 mm (length) × 50 mm (width), and the outermost surface material is peeled off. The tensile strength of the test body at this point was measured as the initial tensile strength Ha (kPa). After mixing the mortar (weber company: Thermplus ultra) and water at a mass ratio of 1:0.27, use a Sany motor (HEIDON company: BL1200) to stir at 500 rpm for 4 minutes. On the outermost layer of the foam that has been stripped of the surface material prepared in the above way, apply the above-mentioned mortar after stirring to a thickness of 7 mm, and cure it for 7 days at 23°C and 50%RH. The cured test body was placed in an environment of 70°C and 95% RH for 14 days, and then placed in an environment of 23°C and 50% RH for 7 days. Measure the tensile strength of the test body after standing, and use it as the tensile strength Hb (kPa) after the alkali resistance test. The strength retention rate of tensile strength was calculated by the following formula (2). Strength retention rate of tensile strength (%) = 100×Hb/Ha

The tensile test was carried out as follows. Use an adhesive (Konishi BondQuick5) to bond the stainless steel with a width of 50 mm, a length of 50 mm, and a thickness of The 2mm jig was placed at room temperature for 24 hours, and then installed on a strength testing machine (Shimadzu, AG-Xplus). The tensile test was carried out at a tensile speed of 3 mm/min, and the maximum load L (N) was obtained. The tensile strength was calculated by the following formula (3). Tensile strength (kPa) = L (N) / area of the most surface of the test body (m ² ) (3)

(Viscosity of phenolic resin or phenolic resin raw material) Using a rotational viscometer (manufactured by Toki Sangyo Co., Ltd., RE-85R type, the rotor part is 3°×R14), set the rotation speed so that the torque value reaches 10% or more, and stabilize at 40°C for 3 minutes. The viscosity value was taken as the measured value.

(Synthesis of phenol resin raw material) 3,500 kg of 52 mass % formaldehyde aqueous solution and 2,510 kg of 99 mass % phenol were added to the reactor. The reaction solution in the reactor was stirred by a propeller rotary stirrer, and the temperature of the reaction solution was adjusted to 40° C. by a temperature regulator. Then, a 50% by mass sodium hydroxide aqueous solution was added until the pH value of the reaction liquid reached 8.7. It took 1.5 hours to raise the temperature of the reaction liquid to 85°C, cool the reaction liquid at the stage when the viscosity of Oswald reached 30 centistokes (=30×10 ^-6 m ² /s, the measured value at 25°C), and add urea 400 kg. Thereafter, the reaction liquid was cooled to 30° C., and a 50% by mass aqueous solution of p-toluenesulfonic acid monohydrate was added until the pH became 6.4. The obtained reaction solution was concentrated by a thin-film evaporator to obtain a phenol resin raw material containing phenol resin. The obtained phenolic resin raw material had a moisture content of 2.4% by mass and a viscosity of 8,800 mPa·s.

(Example 1) With respect to 100 parts by mass of the phenolic resin raw material, 10 parts by mass of calcium sulfate (average particle size: 60 μm) was added as a metal compound by a twin-screw extruder (manufactured by Technovel Co., Ltd.) 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 blowing agent ( n-pentane: nP), 10 parts by mass of a mixture of 80% by mass of xylenesulfonic acid and 20% by mass of diethylene glycol as a catalyst, after uniform mixing, the resulting foamable phenolic resin The pipes are distributed and supplied to the moving surface. Furthermore, a mixer is used in the one disclosed in Japanese Patent Laid-Open No. 10-225993. That is, use a mixer that has an introduction port for a phenolic resin composition containing a solid foaming nucleating agent and a foaming agent on the side of the upper part, and has an acidic acid on the side near the center of the stirring part where the rotor performs stirring. The inlet of hardener. A nozzle for spraying foamable phenolic resin composition is connected after the stirring section. That is, the mixer is configured as follows: before the acid hardener inlet is a mixing section (front stage), from the acid hardener inlet to the end of stirring is a mixing section (rear stage), and from the end of stirring to the nozzle is a distribution section. The dispensing part has a plurality of nozzles at the front end, which is designed to distribute the mixed foamable phenolic resin composition evenly. Furthermore, the distribution part adopts a sleeve-type structure to enable sufficient heat exchange with the tempered water, and the temperature of the tempered water in the distribution part of the mixing head is set at 26°C. In addition, a thermocouple was installed at the discharge port of the multiway distribution pipe so that the average temperature of the central part of the expandable phenol resin composition could be detected. The rotation speed of the mixing head was set at 600 rpm. The mixture ejected from the mixer was sent to a preheated oven at 70° C. by being sandwiched by non-woven fabrics and allowed to stay for 12 minutes. In addition, the average temperature of the central part of the foamable phenolic resin material immediately after ejecting from a mixer was 45 degreeC. Thereafter, it was sent to the first oven at 88° C., and cured with a residence time of 40 minutes, and then cured in the second oven at 110° C. for 2 hours to obtain the phenol resin foam of Example 1.

(Example 2) By changing the rotation speed of the mixing head to 350 rpm, the average temperature of the center of the foamable phenolic resin immediately after being sprayed out of the mixer is 40°C, and obtained in the same manner as in Example 1. The phenolic resin foam of embodiment 2.

(Example 3) By changing the rotation speed of the mixing head to 950 rpm, the average temperature of the central part of the foamable phenolic resin immediately after being sprayed from the mixer is 53°C, and obtained in the same manner as in Example 1. The phenolic resin foam of embodiment 3.

(Example 4) Except having made the addition amount of calcium sulfate 0.8 mass part, it carried out similarly to Example 2, and obtained the phenol resin foam of Example 4.

(Example 5) Except having made the addition amount of calcium sulfate into 15 mass parts, it carried out similarly to Example 3, and obtained the phenol resin foam of Example 5.

(Example 6) The phenol 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 set at 80° C. and the residence time was set at 20 minutes.

(Example 7) Except having changed the metal compound into magnesium sulfate, it carried out similarly to Example 1, and obtained the phenol resin foam of Example 7.

(Embodiment 8) Except having changed the metal compound into iron sulfate (II) heptahydrate, it carried out similarly to Example 1, and obtained the phenol resin foam of Example 8.

(Example 9) Except having changed metal compound into potassium sulfate, it carried out similarly to Example 1, and obtained the phenol resin foam of Example 9.

(Example 10) The phenol resin foam of Example 10 was obtained similarly to Example 6 except having changed the addition amount into 1 mass part using calcium carbonate as a metal compound.

(comparative example 1) Except not adding the calcium sulfate which is a metal compound, it carried out similarly to Example 1, and obtained the phenol resin foam of the comparative example 1.

(comparative example 2) Set the addition amount of calcium sulfate as a metal compound to 0.8 parts by mass, set the rotation speed of the mixing head to 350 rpm, and then change the temperature of the tempering water in the distribution part of the mixing head to 22°C, thereby making the The phenol resin foam of Comparative Example 2 was obtained in the same manner as in Example 1 except that the average temperature of the central part of the foamable phenolic resin after the ejection was 38°C.

(comparative example 3) Change the rotation speed of the mixing head to 950 rpm, and then change the tempering water temperature of the distributing part of the mixing head to 28°C, so that the average temperature of the central part of the foamable phenolic resin immediately after being sprayed out of the mixer becomes 57 degreeC, except having carried out similarly to Example 6, the phenol resin foam of the comparative example 3 was obtained.

The above measurement and evaluation tests were performed on Examples 1 to 10 and Comparative Examples 1 to 3. The measurement results and evaluation results are shown in Tables 1 and 2. [Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Addition amount of metal compound [parts by mass relative to 100 parts by mass of phenolic resin raw material] 10 10 10 0.8 15 15 10 The average temperature of the center of the sprayed foamable phenolic resin [°C] 45 40 53 40 53 53 45 Preforming conditions (temperature × time ) 70℃×12 minutes 70℃×12 minutes 70℃×12 minutes 70℃×12 minutes 70℃×12 minutes 80℃×20 minutes 70℃×12 minutes Added metal compounds[-] Calcium sulfate Calcium sulfate Calcium sulfate Calcium sulfate Calcium sulfate Calcium sulfate magnesium sulfate Existence ratio of metal compound [%] top layer 18.5 16.5 21.3 0.62 22.8 24.7 11.5 center layer 10.5 14.3 12.8 0.6 13.4 14.8 9.6 The value obtained by dividing the ratio of the metal compound in the outermost layer by the ratio of the metal compound in the center layer 1.76 1.15 1.66 1.03 1.70 1.67 1.20 The average bubble diameter of the section obtained by cutting at a position of 5 mm in the thickness direction [μm] 95 110 82 119 80 65 103 Independent bubble rate[%] 91 93 89 92 92 81 91 Thermal conductivity [W/(m・K)] 0.0221 0.022 0.0223 0.0221 0.0223 0.0224 0.0221 Density [kg/m ³ ] 31 30 32 30 30 30 30 Strength retention rate of tensile strength after alkali resistance test [%] 70 64 84 39 82 88 51

[Table 2] Example 8 Example 9 Example 10 Comparative example 1 Comparative example 2 Comparative example 3 Addition amount of metal compound [parts by mass relative to 100 parts by mass of phenolic resin raw material] 10 10 1 0 0.8 15 The average temperature of the center of the sprayed foamable phenolic resin [°C] 45 45 53 45 38 57 Preforming conditions (temperature × time) 70℃×12 minutes 70℃×12 minutes 80℃×20 minutes 70℃×12 minutes 70℃×12 minutes 80℃×20 minutes Added metal compounds[-] Iron(II) Sulfate Heptahydrate potassium sulfate calcium carbonate - Calcium sulfate Calcium sulfate Existence ratio of metal compound [%] top layer 15.3 14.2 1.4 0 0.45 27.2 center layer 12.8 10.3 0.8 0 0.49 15.9 The value obtained by dividing the ratio of the metal compound in the outermost layer by the ratio of the metal compound in the center layer 1.20 1.38 1.75 - 0.92 1.71 The average bubble diameter of the section obtained by cutting at a position of 5 mm in the thickness direction [μm] 105 98 90 98 125 92 Independent bubble rate[%] 90 90 87 92 89 73 Thermal conductivity [W/(m・K)] 0.0223 0.0222 0.022 0.0221 0.0223 0.0232 Density [kg/m ³ ] 30 30 30 30 30 35 Strength retention rate of tensile strength after alkali resistance test [%] 62 55 41 18 27 53

Claims (5)

A phenolic resin foam that satisfies the following (1), (2) and (3), has an independent cell rate of 80% or more, and a foam density of 20 to 80 kg/m ³ , (1) phenolic resin The ratio of the metal compound in the outermost layer of the foam is 0.5-25.0%; (2) The ratio of the metal compound in the center layer of the phenolic resin foam is 0.5-15.0%; The average cell diameter of the section cut parallel to the outermost layer at a position of 5 mm in the thickness direction of the outermost layer of the foam is 50 to 120 μm. For the phenolic resin foam of claim 1, its thermal conductivity at 23°C is 0.0260 W/(m·K) or less. The phenol resin foam according to claim 1 or 2, wherein the ratio of the metal compound in the outermost layer of the phenol resin foam is greater than the ratio of the metal compound in the center layer of the phenol resin foam. The phenolic resin foam according to any one of claims 1 to 3, wherein the metal of the above-mentioned metal compound is at least one selected from the group of calcium, magnesium, zinc, barium, aluminum, iron, sodium, and potassium, and the above-mentioned metal The compound is a metal compound comprising a combination of the aforementioned metal and at least one selected from the group of oxides, chlorides, sulfates, and carbonates. According to any one of claims 1 to 4, the phenolic resin foam has a tensile strength retention rate of 30% or more after the alkali resistance test.