WO2024225405A1 - Phenolic resin foam and method for producing same - Google Patents

Abstract

In the ion chromatogram of a gas component that is generated by heating this phenolic resin foam at 600°C, the ion chromatogram being obtained by a gas chromatography mass spectrometry method, the area ratio Z (Z = X/Y) of the sum X (X = A + B + C) of the area A associated with a dihydroxybenzene, the area B associated with a dihydroxytoluene, and the area C associated with a dihydroxyxylene in the pyrolysis product, to the area Y of the pyrolysis product indicating a structure derived from urea crosslinking is within the range of formula (1). This phenolic resin foam has a thermal conductivity of 0.0240 W/(m∙K) or less in an environment at 23°C. (1): 0.035 ≤ Z ≤ 0.715

Description

Phenolic resin foam and its manufacturing method CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to patent application No. 2023-075252, filed in Japan on April 28, 2023, the entire disclosure of which is incorporated herein by reference.

The present invention relates to a phenolic resin foam and a method for producing the same.

Acid-cured phenolic resin foam made from resol phenolic resin has excellent heat insulation properties, is flame-resistant, and produces little smoke. As a result, it has been used for a long time in building materials such as exterior wall materials like metal siding, interior wall materials like partition panels, ceiling materials, fire doors, and storm shutters, as well as being widely used as a cooling and heat-insulating material for industrial plants.

In recent years, concerns about global warming have made it urgent to reduce greenhouse gas emissions, and the use of plant-derived materials as product raw materials has been attracting attention as one way to reduce greenhouse gases such as carbon dioxide generated during incineration. Foams that use plant-derived materials as raw materials can be considered to have the same amount of carbon dioxide generated during incineration as the amount absorbed by the plant, depending on the amount used, and therefore can be considered a carbon-neutral technology that does not affect the increase or decrease of carbon dioxide in the atmosphere.

Lignin is one of the plant-derived materials that has been considered for use for some time. Lignin is a component recovered when pulp is produced from plants. It is classified into woody and herbaceous plants based on the plant species used as the raw material, and is further classified into kraft lignin, lignosulfonic acid, soda lignin, etc. based on the difference in the method of extracting lignin during pulp production. Because lignin has a phenolic skeleton in its chemical structure, there have been attempts to create composites with phenolic resins.

Patent Document 1 discloses a method for producing a foamed phenolic resin in which lignin sulfonate is added to a phenolic resol to control the foaming and curing speed. Patent Document 2 discloses that a bio-based phenolic resin foam can be provided by adding organosolv lignin or pyrolytic lignin to a condensate of a mixture of phenol, formaldehyde, and a basic catalyst.

Patent No. 1578980 Patent No. 5885855

However, the phenolic resin foam to which lignin sulfonate is added, which is given as an example in Patent Document 1, has a high thermal conductivity, and therefore does not take advantage of the inherently low thermal conductivity of phenolic resin foam. Furthermore, the more the amount of lignin sulfonate added is increased, the longer the curing completion time becomes, which is not desirable from the viewpoint of productivity.

On the other hand, the phenolic resin foam in Patent Document 2 to which organosolv lignin or pyrolytic lignin has been added cannot be said to have sufficient thermal conductivity compared to the phenolic resin foam to which no lignin compound has been added, as in Patent Document 1. In addition, the phenolic resin foam in Patent Document 2 requires 24 hours or more for foaming and hardening, which is undesirable from the viewpoint of productivity.

Therefore, there was a demand for a phenolic resin foam that contains lignin but has low thermal conductivity. Furthermore, there was a demand for technology that shows the same foaming and curing time as phenolic resin foam that does not contain lignin, while also showing the same low thermal conductivity.

The inventors therefore conducted extensive research to solve the above problems, and as a result, they have developed a technology that allows a lignin-containing phenolic resin foam to exhibit the same foaming and curing time and the same thermal conductivity as a lignin-free phenolic resin foam by properly adjusting the moisture content of the lignin and optimizing the moisture content of the lignin-containing phenolic resin composition. That is, the present invention is as follows.

[1]
A phenolic resin foam having a thermal conductivity of 0.0240 W/(m K) or less in a 23° C. environment, wherein in an ion chromatogram obtained by subjecting gas components generated by heating at 600° C. to gas chromatography-mass spectrometry, the total X (X=A+B+C) of the area A derived from dihydroxybenzene, the area B derived from dihydroxytoluene, and the area C derived from dihydroxyxylene, which are pyrolysis products, is a ratio of an area Y (Z=X/Y) to an area Y of the pyrolysis product exhibiting a structure derived from urea crosslinking, falls within the range of the following formula (1):
0.035≦Z≦0.715 (1)
[2]
The phenolic resin foam according to [1], having a density of 10 kg/m3 or ^more and 50 kg/m3 ^or less.
[3]
The phenolic resin foam according to any one of [1] and [2], having an average cell diameter of 70 μm or more and 250 μm or less.
[4]
The phenolic resin foam according to any one of [1] to [3], which contains any one of hydrofluoroolefins, hydrocarbons, and chlorinated hydrocarbons.
[5]
The phenolic resin foam according to any one of [1] to [4], comprising a surface material on at least one of one side of the phenolic resin foam and the back side of the one side.
[6]
A method for producing a phenolic resin foam laminate according to [5], comprising foaming and curing a foamable phenolic resin composition containing lignin on a facing material,
In order to obtain the foamable phenolic resin composition, the method includes at least one of a step of adding lignin to a phenol, a step of adding lignin during synthesis of a phenolic resin, a step of adding lignin to a phenolic resin, and a step of adding lignin to a phenolic resin composition;
The moisture content of the lignin is 34.0% or less,
The water content of the lignin-containing phenolic resin composition in the foamable phenolic resin composition is 1.5 mass % or more and 6.5 mass % or less.
[7]
In the step of adding lignin,
The method for producing a phenolic resin foam laminate according to [6], wherein the median diameter of the lignin powder to be added is 0.1 μm or more and 300 μm or less.

The phenolic resin foam of the present invention can maintain the foaming and curing time even for lignin-containing phenolic resin foams by appropriately adjusting the moisture content of the lignin and the moisture content of the phenolic resin composition to which lignin has been added, and can be produced without reducing productivity. Furthermore, by suppressing foaming inhibition caused by water and maintaining fine cells, even for lignin-containing phenolic resin foams, the thermal conductivity and heat insulating performance can be maintained. Furthermore, by using plant-derived materials, it is possible to provide bio-based phenolic resin foams.

The present invention identifies the conditions for adding plant-derived materials, which are necessary to maintain the foaming and hardening time and thermal insulation performance, and discovers a phenolic resin foam that simultaneously satisfies low thermal conductivity, high productivity, and is bio-based, something that was not previously possible.

The following describes in detail the form for carrying out the present invention (hereinafter, referred to as the "present embodiment"). The present invention is not limited to the following embodiment, and can be carried out in various modifications within the scope of the gist. In this specification, a "phenolic resin" to which a surfactant has been added is referred to as a "phenolic resin composition", and a "phenolic resin composition" containing lignin is particularly referred to as a "lignin-containing phenolic resin composition". A "phenolic resin composition" or a "lignin-containing phenolic resin composition" to which a foaming agent, a foaming nucleating agent, an acidic curing agent, etc. have been added to impart foamability or both foamability and curability is referred to as a "foamable phenolic resin composition". The resulting foam is referred to as a "phenolic resin foam". A laminate having a surface material on at least one of the sides of the phenolic resin foam and the back side of the side is referred to as a "phenolic resin foam laminate".

The phenolic resin foam in the embodiment of the present application contains lignin. The presence or absence of lignin in the phenolic resin foam can be determined by subjecting the phenolic resin foam to pyrolysis gas chromatography mass spectrometry, as described below.

When gas chromatography mass spectrometry is performed on the gas components generated by heating a phenolic resin foam containing lignin at 600°C, if the retention time at which phenol is detected in the obtained total ion chromatogram is t minutes, then in the extracted ion chromatogram of m/z = 110, a pyrolysis product derived from dihydroxybenzene is detected at a retention time of approximately 1.38 x t minutes, in the extracted ion chromatogram of m/z = 124, a pyrolysis product derived from dihydroxytoluene is detected at a retention time of approximately 1.46 x t minutes, a pyrolysis product derived from dihydroxytoluene is detected at a retention time of approximately 1.50 x t minutes, and in the extracted ion chromatogram of m/z = 138, a pyrolysis product derived from dihydroxyxylene is detected at a retention time of approximately 1.58 x t minutes. Phenol is detected at a retention time of approximately 10.0 minutes using the pyrolysis gas chromatography mass spectrometry measurement method described below.

In the extracted ion chromatogram of the obtained pyrolysis product at m/z=110, the area of the pyrolysis product derived from dihydroxybenzene detected at a retention time of about 1.38×t minutes is designated as A, in the extracted ion chromatogram of m/z=124, the sum of the area of the pyrolysis product derived from dihydroxytoluene detected at a retention time of about 1.46×t minutes and the area of the pyrolysis product derived from dihydroxytoluene detected at a retention time of about 1.50×t minutes is designated as B, and in the extracted ion chromatogram of m/z=138, the area of the pyrolysis product derived from dihydroxyxylene detected at a retention time of about 1.58×t minutes is designated as C, and the sum of A, B, and C is designated as X (X=A+B+C). In addition, when the area of the pyrolysis product showing a structure derived from urea crosslinking is designated as Y, the ratio to X is designated as Z (Z=X/Y). The pyrolysis product showing a structure derived from urea crosslinking corresponds to, for example, peak 9 in [Figure 1] of Patent No. 4711469, and is detected in the vicinity of a retention time of 1.50 x t minutes in the total ion chromatogram. In the extracted ion chromatogram, the values of areas A, B, and C differ depending on the type of lignin and change according to the amount of lignin added to the phenolic resin composition. The value of area Y does not change depending on the timing of lignin addition. The areas A, B, C, and Y are calculated using the intersection with the baseline or the inflection point with the adjacent peak as the boundary.

In the ion chromatogram of the obtained pyrolysis product, Z is 0.035 to 0.715, preferably 0.040 to 0.40. More preferably, Z is 0.055 to 0.23, and even more preferably, 0.065 to 0.18. Most preferably, Z is 0.075 to 0.11. If it is less than 0.035, it indicates that the ratio of plant-derived materials in the phenolic resin foam is low, and the value as a bio-based material is low. If it is more than 0.715, it indicates that the ratio of lignin present in the phenolic resin foam is significantly high. However, if the lignin ratio is increased, the viscosity increases when added to the phenolic resin, which is undesirable. In addition, when used as a heat insulating material, the lignin functions as a thermal bridge, increasing the thermal conductivity.

The phenolic resin foam of the present invention contains a foaming agent, which will be described later.

The density of the phenolic resin foam of the present invention may be adjusted to a desired density depending on the purpose of use of the foam, but is preferably 10 kg/m3 or ^more and 50 kg/m3 ^or less, more preferably 20 kg/m3 ^{or more} and 50 kg/m3 ^or less, even more preferably 22 kg/m3 ^or more and 50 kg/m3 ^or less, and most preferably 24 kg/m3 or ^more and 45 kg/ ^m3 or less. When the density is 10 kg/m3 or ^more , the decrease in mechanical strength such as compressive strength and the decrease in surface brittleness, which are likely to occur due to low density, are small, and strength that is practically problem-free can be maintained. When the density is 50 kg/ ^m3 or less, there is less concern that the thermal conductivity will increase due to the heat conduction of the phenolic resin portion, which increases due to high density. The density of the phenolic resin foam can be adjusted by adjusting the filling ratio of the foaming agent in the phenolic resin foam, and can be adjusted to a desired value mainly by changing the amount of foaming agent added to the phenolic resin composition, the temperature of the foamable phenolic resin composition, the timing of pre-molding in the process of discharging the mixed foamable phenolic resin composition, the amount of foaming nucleating agent added, the amount of acidic curing agent added, and curing conditions such as temperature and residence time.

The average bubble diameter of the phenolic resin foam of the present invention is preferably 70 μm or more and 250 μm or less, more preferably 70 μm or more and 130 μm or less. It is even more preferably 70 μm or more and 120 μm or less, and most preferably 70 μm or more and 110 μm or less. When the average bubble diameter is 70 μm or more, the increase in thermal conductivity due to thermal conduction in the phenolic resin part, which increases as the bubble diameter becomes smaller, can be suppressed. Furthermore, when the bubble diameter is 250 μm or less, the heat conduction due to radiation within the bubbles is small, and the increase in thermal conductivity can be suppressed. The average bubble diameter of the phenolic resin foam can be adjusted to a desired value by changing, for example, the amount of solid foaming nucleating agent added, the temperature of the foamable phenolic resin composition, the timing of preforming in the process of discharging the mixed foamable phenolic resin composition onto the lower surface material, and further, the amount of foaming agent added and the amount of acidic curing agent added, and the curing conditions such as temperature and residence time.

The thermal conductivity of the phenolic resin foam in this embodiment at 23°C is 0.024 W/(m·K) or less, preferably 0.02330 W/(m·K) or less. More preferably, it is 0.02230 W/(m·K) or less, even more preferably, it is 0.02150 W/(m·K) or less, and most preferably, it is 0.02115 W/(m·K) or less.

Phenolic resin foam laminates can be used alone or joined to external materials for a variety of applications. Examples of external materials include board-like materials, sheet-like and film-like materials, and combinations thereof. Suitable board-like materials include ordinary plywood, structural plywood, particle board, and wood-based boards such as OSB, wood-wool cement boards, wood-chip cement boards, gypsum boards, flexible boards, medium density fiberboards, calcium silicate boards, magnesium silicate boards, and volcanic glass laminates. Suitable sheet-like and film-like materials include polyester nonwoven fabric, polypropylene nonwoven fabric, inorganic-filled glass fiber nonwoven fabric, glass fiber nonwoven fabric, paper, calcium carbonate paper, polyethylene-processed paper, polyethylene film, plastic moisture-proof film, asphalt waterproof paper, and aluminum foil (with or without holes).

The manufacturing method for phenolic resin foam is explained in more detail below.

<Raw materials for phenolic resin foam>
As the phenolic resin, a resol-type phenolic resin synthesized by an alkali metal hydroxide or an alkaline earth metal hydroxide is used. The resol-type phenolic resin is synthesized by heating phenols and aldehydes as raw materials in a temperature range of 40 to 100°C with an alkali catalyst. In addition, an additive such as urea may be added during or after the synthesis of the resol-type phenolic resin as necessary. When urea is added, it is more preferable to mix urea that has been methylolated with an alkali catalyst in advance with the resol-type phenolic resin. Since the resol-type phenolic resin after synthesis usually contains excess moisture, the moisture content is adjusted to a level suitable for foaming during foaming. In addition, aliphatic hydrocarbons or high-boiling alicyclic hydrocarbons, or mixtures thereof, viscosity-adjusting diluents such as ethylene glycol and diethylene glycol, and other additives such as dicyandiamide and melamine may be added to the phenolic resin as necessary. In addition, lignin may be added during or after the synthesis of the resol-type phenolic resin as necessary.

The starting molar ratio of phenols to aldehydes during synthesis of the phenolic resin is preferably in the range of 1:1 to 1:4.5, more preferably in the range of 1:1.5 to 1:2.5. If necessary, lignin may be dissolved in advance in the phenols used in the synthesis.

Here, in this embodiment, the phenols preferably used in the synthesis of the phenolic resin are phenol itself and other phenols, examples of which include resorcinol, catechol, o-, m- and p-cresol, xylenols, ethylphenols, and p-tert-butylphenol. Dinuclear phenols can also be used.

Also, the aldehydes may be any compound that can be an aldehyde source, and it is preferable to use formaldehyde itself, paraformaldehyde that can be depolymerized for use, and other aldehydes and their derivatives. Examples of other aldehydes include glyoxal, acetaldehyde, chloral, furfural, and benzaldehyde.

The mass average molecular weight of the phenolic resin is preferably 300 or more, more preferably 400 or more, and even more preferably 450 or more. The mass average molecular weight is preferably 2,500 or less, more preferably 2,200 or less, even more preferably 2,050 or less, and most preferably 1,900 or less. When the mass average molecular weight of the phenolic resin is 300 or more, runaway reaction due to the reaction heat of the curing reaction is unlikely to occur, and foam molding can be performed using the reaction heat, resulting in good energy efficiency. When the mass average molecular weight is 2,500 or less, the reaction heat of the polymerization reaction is small, so the bubble diameter tends to be small, and the resin is unlikely to harden in equipment upstream of the board molding process, so the piping is less likely to become dirty, and continuous operation for long periods of time is possible. The mass average molecular weight of the phenolic resin can be measured using the method described in the examples of this specification.

The viscosity of the phenolic resin composition at 40°C is preferably 5,000 mPa·s or more and 100,000 mPa·s or less, more preferably 7,000 mPa·s or more and 50,000 mPa·s or less, and even more preferably 9,000 mPa·s or more and 40,000 mPa·s or less.

The lignin, surfactant, foaming agent and foam nucleating agent may be added to the phenolic resin composition in advance, or may be added simultaneously with the acidic hardener.

As lignin, woody lignin and herbaceous lignin can be used, among which kraft lignin, lignin sulfonic acid, lignin sulfonate, soda lignin, organosolv lignin, explosive lignin, sulfuric acid lignin, alkaline lignin, dealkalized lignin, and their derivatives, modified products, and decomposition products can be used. These lignins can be used alone or in combination of two or more types.

The water content of the lignin-containing phenolic resin composition is 1.5% by mass or more and 6.5% by mass or less, and preferably 1.5% by mass or more and 5.0% by mass or less. More preferably, it is 1.5% by mass or more and 4.8% by mass or less, and even more preferably, it is 1.5% by mass or more and 4.2% by mass or less. Most preferably, it is 4.0% by mass or less. If it is less than 1.5% by mass, the viscosity of the lignin-containing phenolic resin composition increases rapidly, and productivity decreases significantly. If it is more than 6.5% by mass, the water inhibits foaming and curing, and fine cells cannot be maintained, resulting in high thermal conductivity.

The method for adjusting the moisture content of the lignin-containing phenolic resin composition is not particularly limited, but can be appropriately done, for example, by using a thin-film evaporator to control the temperature and vacuum level by steam pressure.

The moisture content of the lignin added to the phenolic resin composition is 34.0% by mass or less, and preferably 11.0% by mass or less. More preferably, it is 7.0% by mass or less, and even more preferably, it is 6.0% by mass or less. Most preferably, it is 5.5% by mass or less. If it is more than 34.0% by mass, the moisture in the lignin that dissipates during foaming and curing is large, which leads to coarsening of the bubble diameter of the foam and increases the thermal conductivity of the foam. Also, if it is more than 34.0% by mass, the viscosity is less likely to increase when the lignin-containing phenolic resin composition, the foaming agent, and the acidic curing agent are mixed in a mixer, the generation of shear heat in the mixer is reduced, and the foaming and curing time is delayed. If it is 34.0% by mass or less, the viscosity increases during mixing, shear heat is generated in the mixer, and the lignin-containing phenolic resin composition is heated in advance, which reduces the curing reaction suppression effect caused by lignin. Therefore, phenolic resin foam containing lignin can be produced in the same foaming and curing time as phenolic resin foam not containing lignin, without impairing productivity.

The method for adjusting the moisture content of the lignin is not particularly limited, but can be appropriately done, for example, by heating or drying the lignin powder using a constant temperature air blower dryer.

The median diameter of the lignin powder is preferably 0.1 μm to 300 μm, more preferably 0.1 μm to 250 μm. Even more preferably, it is 0.1 μm to 200 μm, and most preferably 0.1 μm to 150 μm. If it is larger than 300 μm, the size of the lignin particles in the phenolic resin foam is significantly larger than the bubble diameter of the foam, making the cells more likely to be destroyed and increasing the thermal conductivity.

The method for grinding the lignin powder is not particularly limited, but examples include methods using grinders such as a rolling ball mill, a rolling rod mill, a vibrating ball mill, a vibrating rod mill, a pan mill, a roller mill, and a high-speed rotary mill.

The timing of adding lignin is not particularly limited, but can be determined as desired as long as it is supplied into the mixer that mixes the phenolic resin composition, the foaming agent, and the acidic curing agent. If lignin is added downstream of the mixer, the dispersibility of the lignin in the phenolic resin composition will decrease, resulting in a phenolic resin foam with lignin present locally within the foam. When used as an insulating material, the lignin will function as a thermal bridge, increasing the thermal conductivity. Therefore, it is preferable to add lignin in a process upstream of the mixer that mixes the phenolic resin composition.

The amount of lignin added is preferably 1.0% by mass or more and less than 30.0% by mass, more preferably 1.0% by mass or more and less than 25.0% by mass, more preferably 1.0% by mass or more and less than 25.0% by mass, even more preferably 1.0% by mass or more and less than 12.0% by mass, and most preferably 1.0% by mass or more and less than 8.0% by mass. If the amount of lignin added is less than 1.0% by mass, the ratio of plant-derived materials in the phenolic resin foam is low, and the value as a bio-based material is low. If the amount of lignin added is more than 30.0% by mass, the ratio of lignin present in the phenolic resin foam increases, which is undesirable because the viscosity increases when added to the phenolic resin. In addition, when used as a heat insulating material, the lignin functions as a thermal bridge, increasing the thermal conductivity.

As the surfactant, those generally used in the manufacture of phenolic resin foams can be used, but nonionic surfactants are particularly effective. For example, alkylene oxides, which are copolymers of ethylene oxide and propylene oxide, condensates of alkylene oxides and castor oil, condensation products of alkylene oxides and alkylphenols such as nonylphenol and dodecylphenol, polyoxyethylene alkyl ethers having 14 to 22 carbon atoms in the alkyl ether portion, fatty acid esters such as polyoxyethylene fatty acid esters, silicone compounds such as polydimethylsiloxane, polyalcohols, etc. are preferred. These surfactants may be used alone or in combination of two or more. There are no particular restrictions on the amount used, but they are preferably used in the range of 0.3 to 10 parts by mass per 100 parts by mass of phenolic resin.

Hydrofluoroolefins, hydrocarbons and chlorinated hydrocarbons can be used as blowing agents, either alone or in combination of two or more of these.

Hydrofluoroolefins generally have low thermal conductivity, and are therefore preferred because, when used as a blowing agent, a phenolic resin foam having low thermal conductivity can be obtained. Hydrofluoroolefins include chlorinated hydrofluoroolefins and non-chlorinated hydrofluoroolefins. In the present invention, chlorinated hydrofluoroolefins and non-chlorinated hydrofluoroolefins can also be used in combination.

Chlorinated hydrofluoroolefins include (Z)-1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd(Z)), 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd, for example, E-form (HCFO-1233zd(E)), manufactured by Honeywell Japan, Inc., product name: Solstice (trademark) LBA), 1,1,2-trichloro-3,3,3-trifluoropropene (HCFO-1 213xa), 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 O-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 the like, and one or a mixture of these configuration isomers, i.e., E-isomer and Z-isomer, is used. Further, (E)-1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd(E)) is also included. In the present invention, these chlorinated hydrofluoroolefins can be used in a mixture of two or more kinds.

Non-chlorinated hydrofluoroolefins include 1,3,3,3-tetrafluoroprop-1-ene (HFO-1234ze, for example, E-form (HFO-1234ze(E)), manufactured by Honeywell Japan, Inc., product name: Solstice(trademark) ze), 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz, for example, Z-form (HFO-1336mzz(Z)), manufactured by Chemours Inc., Opteon(trademark) 1100), 2,3,3, Examples of such fluoroolefins include 3-tetrafluoro-1-propene (HFO-1234yf), 1,1,3,3,3-pentafluoropropene (HFO-1225zc), 1,3,3,3-tetrafluoropropene (HFO-1234ze), 3,3,3-trifluoropropene (HFO-1243zf), and 1,1,1,4,4,5,5,5-octafluoro-2-pentene (HFO-1438mzz). One or a mixture of these configurational isomers, i.e., E-isomer or Z-isomer, is used. In the present invention, these non-chlorinated hydrofluoroolefins can also be used in a mixture of two or more kinds.

The preferred hydrocarbons are cyclic or chain alkanes, alkenes, and alkynes having 3 to 7 carbon atoms, and specific examples include normal butane, isobutane, cyclobutane, normal pentane, isopentane, cyclopentane, neopentane, normal hexane, isohexane, 2,2-dimethylbutane, 2,3-dimethylbutane, and cyclohexane. Of these, pentanes such as normal pentane, isopentane, cyclopentane, and neopentane, and butanes such as normal butane, isobutane, and cyclobutane are preferably used. In the present invention, these hydrocarbons can also be used in a mixture of two or more types. Examples of mixtures include normal pentane and normal butane, isobutane and isopentane, normal butane and isopentane, isobutane and normal pentane, cyclopentane and normal butane, cyclopentane and isobutane, and the mixture of cyclopentane and isobutane is particularly preferred.

As the chlorinated hydrocarbon, linear or branched chlorinated aliphatic hydrocarbons having 2 to 5 carbon atoms can be preferably used. The number of bonded chlorine atoms is preferably 1 to 4, and examples thereof include dichloroethane, propyl chloride, 2-chloropropane, butyl chloride, isobutyl chloride, pentyl chloride, and isopentyl chloride. Of these, propyl chloride and 2-chloropropane, which are chloropropanes, are more preferably used. In the present invention, these chlorinated hydrocarbons can also be used in combination of two or more types.

Furthermore, other foaming agents are not particularly limited, and examples thereof include chemical foaming agents such as sodium hydrogen carbonate, sodium carbonate, calcium carbonate, magnesium carbonate, azodicarboxylic acid amide, azobisisobutyronitrile, barium azodicarboxylate, N,N'-dinitrosopentamethylenetetramine, p,p'-oxybisbenzenesulfonylhydrazide, and trihydrazinotriazine. These foaming agents may be used alone or in combination of two or more.

The amount of foaming agent in the phenolic resin composition varies depending on the type of foaming agent, the compatibility of the foaming agent with the phenolic resin, the temperature, and the foaming and curing conditions such as the residence time. Therefore, it may be determined arbitrarily depending on the desired density of the phenolic resin foam, the foaming conditions, etc., but the amount of foaming agent is preferably 3.0 to 20 parts by mass, more preferably 4.0 to 18 parts by mass, even more preferably 5.0 to 16 parts by mass, and most preferably 6.0 to 15 parts by mass, per 100 parts by mass of the phenolic resin composition. When the amount of foaming agent per 100 parts by mass of the phenolic resin composition is 3.0 parts by mass or more, the resin foam can be prevented from becoming highly densified. Also, when the amount of foaming agent per 100 parts by mass of the phenolic resin composition is 20 parts by mass or less, the phenolic resin foam can be prevented from becoming low-densified, which would result in a decrease in mechanical strength such as compressive strength, and an increase in thermal conductivity.

In this embodiment, a foam nucleating agent may be used to manufacture the phenolic resin foam. As the foam nucleating agent, a gaseous foam nucleating agent such as nitrogen, helium, argon, or other low-boiling substances having a boiling point 50° C. or more lower than that of the foaming agent may be added. In addition, a solid foam nucleating agent such as inorganic powders such as aluminum hydroxide powder, aluminum oxide powder, calcium carbonate powder, talc, kaolin, silica stone powder, silica sand, mica, calcium silicate powder, wollastonite, glass powder, glass beads, fly ash, silica fume, gypsum powder, borax, slag powder, alumina cement, and Portland cement, and an organic powder such as crushed powder of phenolic resin foam may also be added. These may be used alone, or two or more types may be used in combination, regardless of whether they are gaseous or solid. The timing of adding the foam nucleating agent may be determined arbitrarily, as long as it is supplied into the mixer that mixes the phenolic resin composition.

When a gas foam nucleating agent is added, the amount added is preferably 0.2% by mass or more and 1.0% by mass or less, and more preferably 0.3% by mass or more and 0.5% by mass or less, based on 100% by mass of the foaming agent.

The amount of solid foam nucleating agent added is preferably 3.0% by mass or more and 10.0% by mass or less, and more preferably 3.0% by mass or more and 8.0% by mass or less, relative to 100 parts by mass of the phenolic resin composition. When the amount of solid foam nucleating agent added is 3.0% by mass or more, it becomes easier to suppress the seepage of the foamable phenolic resin composition from the surface material. In addition, by setting the amount of solid foam nucleating agent added to 10.0% by mass or less, it becomes easier to suppress the emission of a foaming agent with a low boiling point.

The acidic curing agent may be any acidic curing agent capable of curing the phenolic resin composition, and contains an organic acid as an acid component. The organic acid is preferably arylsulfonic acid or an anhydride thereof. Examples of arylsulfonic acid and anhydrides thereof include toluenesulfonic acid, xylenesulfonic acid, phenolsulfonic acid, substituted phenolsulfonic acid, xylenolsulfonic acid, substituted xylenolsulfonic acid, dodecylbenzenesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, and the like, and anhydrides thereof. These may be used alone or in combination of two or more. In this embodiment, resorcinol, cresol, saligenin (o-methylolphenol), p-methylolphenol, and the like may be added as a curing aid. These acidic curing agents may also be diluted with a solvent such as ethylene glycol or diethylene glycol.

The amount of acidic hardener used varies depending on the type. When using a mixture of 80% by weight of xylene sulfonic acid and 20% by weight of diethylene glycol, it is preferably used in an amount of 6 to 20 parts by weight, more preferably 8 to 15 parts by weight, and most preferably 11 to 13 parts by weight, per 100 parts by weight of the phenolic resin composition.

A flexible surface material (flexible surface material) is used as the surface material arranged on at least one of the sides of the phenolic resin foam and the back surface of the side. The flexible surface material used is preferably a nonwoven or woven fabric whose main components are polyester, polypropylene, nylon, etc., paper such as craft paper, glass fiber mixed paper, calcium hydroxide paper, aluminum hydroxide paper, magnesium silicate paper, or inorganic fiber nonwoven fabric such as glass fiber nonwoven fabric, and these may be mixed (or laminated) and used. When the surface material is peeled off from the obtained phenolic resin foam laminate and only the base material is used, inexpensive paper that can be disposed of after peeling is preferred. These surface materials are usually provided in a roll form. Furthermore, the flexible surface material may be mixed with additives such as flame retardants. There are no particular limitations on the method of bonding the surface material and the phenolic resin foam, and an adhesive such as an epoxy resin may be used, but from the standpoint of production costs and preventing the manufacturing process from becoming complicated, it is preferable that the bonding be achieved only by the adhesive strength that occurs when the foamable phenolic resin composition is thermally cured on the surface of the surface material.

<Method of manufacturing phenolic resin foam and laminate thereof>
The method for producing the phenolic resin foam laminate is a continuous production method including a mixing step of mixing the above-mentioned foamable phenolic resin composition in a mixer, a discharge step of discharging the mixed foamable phenolic resin composition onto a lower surface material, and a foam laminate production step of producing a phenolic resin foam laminate from the foamable phenolic resin composition discharged onto the lower surface material. It is also possible to adopt a batch method using a mold in which each step is performed in stages. It can also be used as a phenolic resin foam by not laminating a surface material or by removing the surface material.

In the continuous manufacturing method, the phenolic resin composition discharged onto the lower surface material is covered with the upper surface material, and then preformed to be uniform from the top and bottom while foaming and curing, and then formed into a plate shape while proceeding with foaming and curing. In the continuous manufacturing method, various methods according to the manufacturing purpose can be mentioned as a method for performing preforming and forming in the continuous manufacturing method, such as a method using a slat type double conveyor, a method using a metal roll or a steel plate, and a method using a combination of a plurality of these. Among these, for example, when molding using a slat type double conveyor, the foamable phenolic resin composition covered with the upper and lower surface materials can be continuously guided into the slat type double conveyor, and then it can be foamed and cured while adjusting to a predetermined thickness by applying pressure from the top and bottom while heating, and formed into a plate shape. The temperature of the foamable phenolic resin composition when discharged onto the lower surface material depends on the boiling point of the foaming agent, but it is generally preferable that it is 32°C or higher and 45°C or lower. When the temperature of the foamable phenolic resin composition is 32°C or higher, the foamable phenolic resin composition is easily foamed in the early stages, and therefore it is easy to suppress the seepage of the foamable phenolic resin composition from the lower surface material. On the other hand, when the temperature of the foamable phenolic resin composition is 45°C or lower, it is easy to suppress the diffusion even when a foaming agent with a low boiling point is used, and it is easy to prevent the decrease in foaming efficiency and the increase in thermal conductivity due to the coarsening of the bubble diameter. The temperature of the foamable phenolic resin composition discharged onto the lower surface material can be adjusted by adjusting the temperature and flow rate of the water temperature of the mixer that mixes the various compositions, as well as the rotation speed, etc.

<Preforming process>
The heating temperature control conditions for the process of foaming and curing the foamable phenolic resin composition discharged onto the lower surface material while preforming from the upper surface material are desirably 30°C or higher and 80°C or lower. If the temperature is 30°C or higher, the foaming promotion effect in the preforming process is easily obtained, and curing can be promoted. If the temperature is 80°C or lower, the vicinity of the center in the thickness direction is not easily affected by internal heat generation, the center temperature is not easily increased, and the thermal conductivity can be maintained for a long period of time. When foaming and curing the foamable phenolic resin composition, in order to efficiently promote curing while suppressing internal heat generation in the vicinity of the center in the thickness direction, it is important to provide a main molding process and a post-curing process following the preforming process and to raise the temperature stepwise. The residence time in the preforming process is preferably 1 minute or more and 20 minutes or less.

<Main molding process>
The heating temperature control conditions of the main molding process following the pre-molding process are preferably 65°C or higher and 100°C or lower. In this section, the main molding can be performed using an endless steel belt type double conveyor or a slat type double conveyor, or a roll or the like. In addition, since the main molding process is a main process for carrying out foaming and curing reactions, the residence time is preferably 5 minutes or more and 40 minutes or less. If the residence time is 5 minutes or more, foaming and curing can be sufficiently promoted. If the residence time is 2 hours or less, the production efficiency of the phenolic resin foam laminate can be increased. In addition, when using a conveyor, it is preferable that the temperature difference between the upper and lower conveyors is less than 4°C.

<Post-curing process>
After heating and temperature control through the temperature control sections of the pre-molding process and the main molding process, the post-curing process is applied. The temperature of the post-curing process is preferably 90°C or higher and 120°C or lower. If it is 90°C or higher, the moisture in the foam is easily dissipated, and if it is 120°C or lower, the low thermal conductivity of the product can be maintained for a long period of time. By providing a temperature control section in the post-curing process, the moisture in the foamable phenolic resin composition can be dissipated after final molding. The residence time in the post-curing process is preferably 60 minutes or more and 300 minutes or less.

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

<Synthesis of phenolic resin>
3,500 kg of 52% by mass formaldehyde aqueous solution (52% by mass formalin) and 2,510 kg of 99% by mass phenol (containing water as an impurity) were charged into the reactor, and the mixture was stirred with a propeller-rotating agitator, and the temperature of the liquid inside the reactor was adjusted to 40° C. with a temperature controller. The reaction was then carried out by raising the temperature while adding a 48% by mass aqueous sodium hydroxide solution. When the Ostwald viscosity of the reaction liquid reached 110 centistokes (=110×10 ⁻⁶ m ² /s, measured value at 25° C.), the reaction liquid was cooled and 398 kg of urea was added. Thereafter, the reaction liquid was cooled to 30° C., and neutralized to pH 6.4 with a 50% by mass aqueous solution of paratoluenesulfonic acid monohydrate.

This reaction liquid was concentrated at 60°C to obtain a phenolic resin. The mass average molecular weight and viscosity at 40°C of the phenolic resin were measured using the following methods, and the mass average molecular weight was 500, the viscosity at 40°C was 9,730 mPa·s, and the water content was 4.0% by mass.

<Mass average molecular weight of phenolic resin>
Measurement was carried out by gel permeation chromatography (GPC) under the following conditions, and the mass average molecular weight Mw of the phenol resin was determined from a calibration curve obtained using standard substances (standard polystyrene, 2-hydroxybenzyl alcohol and phenol) shown below.
Pretreatment:
About 10 mg of phenol resin was dissolved in 1 ml of N,N-dimethylformamide (Fujifilm Wako Pure Chemical Industries, Ltd., for high performance liquid chromatography), and filtered through a 0.2 μm membrane filter to prepare a measurement solution.
Measurement conditions:
Measuring device: Shodex System 21 (manufactured by Showa Denko K.K.)
Column: Shodex Asahipak GF-310HQ (7.5 mm I.D. x 30 cm)
Eluent: 0.1% by mass of lithium bromide dissolved in N,N-dimethylformamide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., for high performance liquid chromatography) was used.
Flow rate: 0.6 ml/min Detector: RI detector Column temperature: 40° C.
Standard material: Standard polystyrene (Shodex STANDARD manufactured by Showa Denko K.K.)
SL-105), 2-hydroxybenzyl alcohol (Sigma-Aldrich, 99% product), phenol (Kanto Chemical Co., Ltd., special grade)

<Viscosity measurement of phenolic resin>
A rotational viscometer (manufactured by BrookField Metek, DVNXHBCBG type, rotor part CPA-52Z) was used, and the measured value after stabilizing 0.5 ml of the phenolic resin at 40° C. for 6 minutes was taken as the viscosity of the phenolic resin.

Example 1
A composition containing 50% by mass of ethylene oxide-propylene oxide block copolymer and polyoxyethylene dodecyl phenyl ether as surfactants was mixed in a ratio of 3.0 parts by mass per 100 parts by mass of phenolic resin. This is the phenolic resin composition. As the lignin, lignin (dealkalized) (manufactured by Tokyo Chemical Industry Co., Ltd.) obtained by the sulfite method, which had been previously heated and dried at 120°C for 20 minutes in a constant temperature air dryer and then pulverized, and having a median diameter of 25.7 μm and a moisture content of 10.2 mass%, was added in an amount of 8.0 mass% per 100 parts by mass of the phenolic resin composition containing the surfactant. This is the lignin-containing phenolic resin composition. When the lignin-containing phenolic resin composition was concentrated with a thin film evaporator, the moisture content was 4.20 mass%. In addition, 13 parts by mass of a composition consisting of a mixture of 70% by mass of cyclopentane and 30% by mass of isobutane as a foaming agent, 0.4% by mass of nitrogen as a gas foaming nucleating agent relative to the foaming agent, and 13 parts by mass of a composition consisting of a mixture of 80% by mass of xylene sulfonic acid and 20% by mass of diethylene glycol as an acidic hardener were added to 100 parts by mass of the lignin-containing phenolic resin composition, and the mixture was supplied to a variable speed mixing head whose temperature was controlled at 17°C. The lignin was kneaded with the phenolic resin composition in a twin-screw extruder before the addition of the foaming agent and the acidic hardener. Thereafter, the gas foaming nucleating agent, the foaming agent, and the acidic hardener were mixed in a mixer, and the obtained foamable phenolic resin composition was distributed in a multi-port distribution pipe and supplied onto the moving lower surface material. The mixer (mixer) used was the one disclosed in FIG. 1 of JP-A-10-225993. That is, a mixer was used in which an inlet for the lignin-containing phenolic resin composition and an inlet for the foaming agent were arranged adjacent to each other on the upper side of the mixer, and an inlet for the acidic curing agent was provided on the side near the center of the stirring section where the rotor stirs. The stirring section and subsequent sections were connected to a nozzle for discharging the foamable phenolic resin composition. That is, the mixer is composed of a mixing section (front stage) up to the acidic curing agent inlet, a mixing section (rear stage) from the acidic curing agent inlet to the stirring end section, and a distribution section from the stirring end section to the nozzle. The distribution section has multiple nozzles at the tip and is designed to distribute the mixed foamable phenolic resin composition uniformly. Furthermore, the distribution section has a jacketed structure so that sufficient heat exchange can be performed using temperature-controlled water, and the temperature of the temperature-controlled water in the distribution section was set to 17°C. In addition, a thermocouple was installed at the outlet of the multi-port distribution pipe so that the temperature of the foamable phenolic resin composition could be detected, and the rotation speed of the mixer was set to 500 rpm. The temperature of the foamable phenolic resin composition discharged onto the lower surface material at this time was 34°C. The foamable phenolic resin composition supplied onto the lower surface material was introduced into a pre-molding process controlled at 40°C, and after 30 seconds, pre-molding was performed from above the upper surface material with a free roller. The residence time in this process was 5 minutes. Thereafter, the composition was sandwiched between two surface materials and introduced into a slat-type double conveyor heated to 69°C (main molding process), cured for a residence time of 15 minutes, then retained at 100°C for 9 minutes, and cured at 110°C for 2 hours (post-curing process), to obtain a phenolic resin foam laminate of Example 1 having a thickness of about 30 mm. As the surface material, polyester nonwoven fabric (Eltas E05060, Asahi Kasei Corporation, basis weight 60 g/ ^m2 ) was used for both the upper and lower surface materials. This manufacturing method is indicated as manufacturing method A in Table 2. The foaming and hardening rate of the foamable phenolic resin composition containing lignin supplied onto the lower surface material was equivalent to that of the foamable phenolic resin composition not containing lignin (Comparative Example 1 described below).

The characteristics of the lignin powder used were evaluated using the following method.

<Measurement of median diameter of lignin powder>
The median diameter of the lignin powder was measured using a laser diffraction light scattering type particle size distribution measuring device (Microtrack HRA; 9320-X100, manufactured by Nikkiso Co., Ltd.) after treating the lignin powder with ultrasound for 1 minute to uniformly disperse it in water.

<Measurement of moisture content of lignin powder>
The moisture content of the lignin powder was calculated using a moisture meter (Shimadzu Corporation, MOC63u) by heating 0.5 g of the powder at 120° C. for 20 minutes, and then dividing the difference between the mass before and after heating, M (g), by the mass before heating, according to the following formula:
Moisture content (mass%) = ((0.5-M)/0.5) x 100

The properties of the phenolic resin composition and lignin-containing phenolic resin composition used were evaluated using the following methods.

<Measurement of Moisture Content of Phenolic Resin Composition and Lignin-Containing Phenolic Resin Composition>
The moisture content of the phenolic resin composition and the lignin-containing phenolic resin composition was measured using a volumetric titration Karl Fischer moisture meter (Kyoto Electronics Manufacturing Co., Ltd., MKV-710) using Chem-Aqua titrant TR-3 (Kyoto Electronics Manufacturing Co., Ltd.) as the Karl Fischer reagent and Chem-Aqua dehydrating solvent MET (Kyoto Electronics Manufacturing Co., Ltd.) as the dehydrating solvent.

The properties of the obtained phenolic resin foam and phenolic resin foam laminate were evaluated (identification of the lignin components in the phenolic resin foam, measurement of density, measurement of the thermal conductivity of the phenolic resin foam laminate at 23°C, measurement of the average cell diameter of the phenolic resin foam, and identification of the type of blowing agent in the phenolic resin foam) using the following methods.

<Identification of lignin components in phenolic resin foam>
A phenolic resin foam laminate was used as a sample. After removing the surface material from the sample, pyrolysis gas chromatography mass spectrometry was performed under the following measurement and analysis conditions to identify the lignin components present in the phenolic resin foam.

<Conditions for pyrolysis gas chromatography mass spectrometry (GC-MS) measurement>
GC device: Agilent Technologies 7890B
Column: DB1 (30 m, 0.25 mm diameter, liquid phase thickness 0.25 μm)
Column temperature: 40°C (5 min) → (10°C/min. temperature increase) → 320°C (12 min hold)
Flow rate: 1 ml/min constant flow Inlet temperature: 300° C.
Injection method: split method (split ratio 100:1)
MS device: JEOL RESONANCE, JMS-Q1500GC
Interface temperature: 300°C
Ionization method: EI (electron ionization) method 70 eV (temperature 230° C.)
Pyrolysis device: Frontier-lab EGA/PY-3030D
Thermal decomposition temperature: 600°C (under He atmosphere)
Scan range: m/z 10-800
Sample amount: 1 mg

In gas chromatography mass spectrometry, if the retention time at which phenol is detected in the obtained total ion chromatogram is t minutes, then in the extracted ion chromatogram of m/z = 110, a pyrolysis product derived from dihydroxybenzene is detected at a retention time of approximately 1.38 x t minutes, in the extracted ion chromatogram of m/z = 124, a pyrolysis product derived from dihydroxytoluene is detected at a retention time of approximately 1.46 x t minutes, a pyrolysis product derived from dihydroxytoluene is detected at a retention time of approximately 1.50 x t minutes, and in the extracted ion chromatogram of m/z = 138, a pyrolysis product derived from dihydroxyxylene is detected at a retention time of approximately 1.58 x t minutes. Note that, by the above pyrolysis gas chromatography mass spectrometry measurement method, phenol was detected at a retention time of approximately 10.0 minutes.

In the ion chromatogram of the obtained pyrolysis products, the area of the pyrolysis product derived from dihydroxybenzene detected near the retention time of 1.38×t minutes in the extracted ion chromatogram of m/z=110 is defined as A, the sum of the area of the pyrolysis product derived from dihydroxytoluene detected near the retention time of 1.46×t minutes in the extracted ion chromatogram of m/z=124 and the area of the pyrolysis product derived from dihydroxytoluene detected near the retention time of 1.50×t minutes in the extracted ion chromatogram of m/z=124 is defined as B, the area of the pyrolysis product derived from dihydroxyxylene detected near the retention time of 1.58×t minutes in the extracted ion chromatogram of m/z=138 is defined as C, and the sum of A, B, and C is defined as X (X=A+B+C). In addition, when the area of the pyrolysis product that corresponds to peak 9 in [Figure 1] of Patent No. 4711469 and shows a structure derived from urea crosslinking detected in the total ion chromatogram at a retention time of about 1.50 x t minutes is taken as Y, the ratio to X was calculated as Z (Z = X/Y). In addition, the areas A, B, C, and Y were calculated using the intersection with the baseline or the inflection point with the adjacent peak as the boundary.

<Measurement of density of phenolic resin foam>
A 200 mm square phenolic resin foam laminate was used as a sample, and after removing the surface material from the sample, the mass and apparent volume were measured in accordance with JIS K7222.

<Measurement of thermal conductivity of phenolic resin foam laminate in a 23°C environment>
In accordance with JIS A 1412-2:1999, the thermal conductivity in the thickness direction of the resin foam laminate was measured in an environment of 23° C. by the following method. The specific procedure is as follows.

The phenolic foam laminate was cut into 300 mm squares and placed in an atmosphere of 23±1°C and 50±2% humidity. The weight change over time was then measured every 24 hours, and the condition was checked and adjusted until the weight change after 24 hours was 0.2% by mass or less. The conditioned phenolic foam laminate specimen was introduced into a thermal conductivity measuring device placed in an atmosphere of 23±1°C and 50±2% humidity. If the thermal conductivity measuring device was not placed in the room controlled at 23±1% and 50±2% humidity where the phenolic foam laminate specimen was placed, the specimen whose condition had been checked and adjusted in the aforementioned atmosphere was immediately placed in a polyethylene bag, the bag was closed, and the specimen was removed from the bag within one hour, and the thermal conductivity was immediately measured.

Thermal conductivity measurements were performed with a low temperature plate at 13°C and a high temperature plate at 33°C using a measuring device with a single test piece and a symmetrical configuration (Eiko Seiki Co., Ltd., product name "HC-074/FOX304").

<Measurement of average cell diameter of phenolic resin foam>
The average bubble diameter was measured by the following method: A phenolic resin foam laminate was used as a sample, and after removing the surface material from the sample, four photographs of bubbles at approximately the center in the thickness direction of the phenolic resin foam and at approximately the center and the center relative to the front and back surfaces were taken with a scanning electron microscope at a magnification of 50 times, four straight lines 90 mm long (corresponding to 1,800 μm in the cross section of the actual foam) were drawn on the obtained photographs while avoiding voids, and the number of bubbles was measured according to the number of bubbles crossed by each straight line for each line, and the average value of these values was divided by 1,800 μm to obtain the average bubble diameter.

<Identification of blowing agent species in phenolic resin foam>
First, the retention times were determined under the following GC/MS measurement conditions using standard gases of halogenated hydrocarbons and hydrocarbons.

Phenolic resin foam laminate was used as the sample, and after removing the surface material from the sample, 0.25 mg of sample was cut out from near the center of the phenolic resin foam and placed in a dedicated container, to which 10 ml of chloroform and 12 crushed glass beads were added. The sample was crushed in a homogenizer (IKA ULTRA-TURRAX Tube Drive) at 6000 rpm for 7 to 11 min while extracting the components into chloroform, after which the extract was filtered through a 0.45 μm filter and subjected to GC/MS measurement. The components to be quantified were dissolved in chloroform to prepare standard sample solutions of known concentrations, which were subjected to GC/MS measurement under the same conditions as the sample.

Halogenated hydrocarbons and hydrocarbons were identified from the retention times and mass spectra obtained in advance. Separately, the detection sensitivity of each generated gas component was measured using a standard gas, and the content of each substance was calculated from the detection area and detection sensitivity of each gas component obtained by GC/MS. The mass percentage of each blowing agent component in the phenolic resin foam was calculated from the content of each identified gas component and the content and molar mass of the blowing agent.

Example 2
A phenolic resin foam laminate of Example 2 was produced in the same manner as in Example 1, except that the lignin was changed to lignin (alkali) (manufactured by Tokyo Chemical Industry Co., Ltd.) obtained by the sulfite method with a median diameter of 26.8 μm and a moisture content of 5.3 mass%. The moisture content of the lignin-containing phenolic resin composition after concentration was 3.85 mass%. The foaming and curing speed of the foamable phenolic resin composition containing lignin supplied onto the lower surface material was equivalent to that of the foamable phenolic resin composition not containing lignin (Comparative Example 1 described later).

Example 3
A phenolic resin foam laminate of Example 3 was produced in the same manner as in Example 1, except that the lignin was not pulverized and was changed to lignin sulfonic acid sodium salt having a median diameter of 238.5 μm and a moisture content of 5.0 mass%. The moisture content of the lignin-containing phenolic resin composition after concentration was 3.83 mass%. The foaming and curing speed of the foamable phenolic resin composition containing lignin supplied onto the lower surface material was equivalent to that of the foamable phenolic resin composition not containing lignin (Comparative Example 1 described later).

Example 4
A phenolic resin foam laminate of Example 4 was produced in the same manner as in Example 1, except that the lignin was changed to kraft lignin having a median diameter of 23.9 μm and a moisture content of 6.5% by mass. The moisture content of the lignin-containing phenolic resin composition after concentration was 3.93% by mass. The foaming and curing rate of the foamable phenolic resin composition containing lignin supplied onto the lower surface material was equivalent to that of the foamable phenolic resin composition not containing lignin (Comparative Example 1 described later).

Example 5
A phenolic resin foam laminate of Example 5 was produced in the same manner as in Example 1, except that the amount of lignin added to 100 parts by mass of the phenolic resin composition was 1.0 mass%. The water content of the lignin-containing phenolic resin composition after concentration was 3.80 mass%. The foaming and curing speed of the foamable phenolic resin composition containing lignin supplied onto the lower surface material was equivalent to that of the foamable phenolic resin composition not containing lignin (Comparative Example 1 described later).

Example 6
A phenolic resin foam laminate of Example 6 was produced in the same manner as in Example 1, except that the amount of lignin added relative to 100 parts by mass of the phenolic resin composition was 12.0% by mass. The water content of the lignin-containing phenolic resin composition after concentration was 4.40% by mass. The foaming and curing rate of the foamable phenolic resin composition containing lignin supplied onto the lower surface material was equivalent to that of the foamable phenolic resin composition not containing lignin (Comparative Example 1 described later).

(Example 7)
A phenolic resin foam laminate of Example 7 was produced in the same manner as in Example 1, except that the amount of lignin added relative to 100 parts by mass of the phenolic resin composition was 20.0 mass%. The water content of the lignin-containing phenolic resin composition after concentration was 4.78 mass%. The foaming and curing rate of the foamable phenolic resin composition containing lignin supplied onto the lower surface material was equivalent to that of the foamable phenolic resin composition not containing lignin (Comparative Example 1 described later).

(Example 8)
The phenolic resin foam laminate of Example 8 was produced in the same manner as in Example 1, except that the amount of lignin added relative to 100 parts by mass of the phenolic resin composition was 25.0 mass%. The water content of the lignin-containing phenolic resin composition after concentration was 4.99 mass%. The foaming and curing rate of the foamable phenolic resin composition containing lignin supplied onto the lower surface material was equivalent to that of the foamable phenolic resin composition not containing lignin (Comparative Example 1 described later).

(Example 9)
A phenolic resin foam laminate of Example 9 was produced in the same manner as in Example 1, except that the amount of lignin added relative to 100 parts by mass of the phenolic resin composition was 29.0 mass%. The water content of the lignin-containing phenolic resin composition after concentration was 5.15 mass%. The foaming and curing rate of the foamable phenolic resin composition containing lignin supplied onto the lower surface material was equivalent to that of the foamable phenolic resin composition not containing lignin (Comparative Example 1 described later).

(Example 10)
The phenolic resin foam laminate of Example 10 was produced in the same manner as in Example 1, except that the lignin was changed to kraft lignin having a median diameter of 23.9 μm and a moisture content of 6.5% by mass, and the amount of lignin added to 100 parts by mass of the phenolic resin composition was 29.0% by mass. The moisture content of the lignin-containing phenolic resin composition after concentration was 4.33% by mass. The foaming and curing speed of the foamable phenolic resin composition containing lignin supplied onto the lower surface material was equivalent to that of the foamable phenolic resin composition not containing lignin (Comparative Example 1 described later).

Example 11
A phenolic resin foam laminate of Example 11 was produced in the same manner as in Example 1, except that 2.7 mass% of water was added to 100 mass parts of the phenolic resin composition containing a surfactant, and the water content of the lignin-containing phenolic resin composition after concentration was set to 6.50 mass%. The foaming and curing rate of the lignin-containing foamable phenolic resin composition supplied onto the lower surface material was equivalent to that of the lignin-free foamable phenolic resin composition (Comparative Example 1 described later).

Example 12
A phenolic resin foam laminate of Example 12 was produced in the same manner as in Example 1, except that the foaming agent was (Z)-1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd(Z)). The water content of the lignin-containing phenolic resin composition after concentration was 4.20 mass%. The foaming and curing rate of the lignin-containing foamable phenolic resin composition supplied onto the lower surface material was equivalent to that of the lignin-free foamable phenolic resin composition (Comparative Example 1 described later).

Example 13
A composition containing 50% by mass of ethylene oxide-propylene oxide block copolymer and polyoxyethylene dodecyl phenyl ether as surfactants was mixed in a ratio of 3.0 parts by mass per 100 parts by mass of phenolic resin. This is the phenolic resin composition. As the lignin, lignin (de-alkalized) (manufactured by Tokyo Chemical Industry Co., Ltd.) obtained by the sulfite method, which had a median diameter of 25.7 μm and a moisture content of 10.2 mass% and had been previously heated and dried at 120° C. for 20 minutes in a constant temperature air dryer and then pulverized, was placed in a polycup so that the content was 8.0 mass% per 100 parts by mass of the phenolic resin composition containing the surfactant, and the mixture was kneaded with a cordless driver drill (Hi-Koki DS 10DAL) equipped with a stirring rod. This is the lignin-containing phenolic resin composition. When the lignin-containing phenolic resin composition was concentrated with a thin film evaporator, the moisture content was 4.20 mass%. In addition, the lignin-containing phenolic resin composition was kneaded with a cordless driver drill so that 12 parts by mass of normal pentane was used as a foaming agent per 100 parts by mass of the lignin-containing phenolic resin composition. Here, no gas foaming nucleating agent was added, but the air entrained during kneading played the role of the foaming nucleating agent. It was confirmed from the change in the weight of the resin composition that the predetermined amount of each was kneaded. Next, the polycup containing the foamable phenolic resin composition was cooled in a refrigerator for 1 hour, and after confirming that the foamable phenolic resin composition was 12°C or less, 13 parts by mass of a composition consisting of a mixture of 80% by mass of xylene sulfonic acid and 20% by mass of diethylene glycol was added as an acidic curing agent, and kneaded for 2 minutes with a cordless driver drill. Next, the foamable phenolic resin composition was applied to the bottom surface of a metal frame (mold) with a spatula in an environment of 23°C. The amount of the foamable phenolic resin composition applied was appropriately adjusted so that the thickness did not protrude from the metal frame (mold) after foaming. The metal frame (mold) used here is made of metal with a thickness of 2.0 mm, an inner diameter of 300 mm x 300 mm x 30 mm in height, and the bottom surface is punched with holes of 5 mm in diameter at 1 mm intervals, and polyester nonwoven fabric (Asahi Kasei Corporation Eltas E05060, basis weight 60 g/m ² ) is laid on the bottom surface as a surface material. The work time from mixing the foamable phenolic resin composition and the acidic curing agent to finishing the application was 5 minutes. After that, as a top plate, a plate larger than 300 mm x 300 mm with the same punching specifications as the bottom surface and the same surface material as the bottom surface of the metal frame (mold) was attached to it, and the top plate was fixed to the metal frame (mold) with a clip. The metal frame (mold) was placed in an oven heated to 85°C, and a 25 kg weight heated to 85°C was placed on the center of the top plate of the metal frame (mold) and heated for 1 hour, followed by curing at 105°C for 1 hour to obtain a phenolic resin foam laminate of Example 13 having a thickness of 30 mm. This manufacturing method is shown as Manufacturing Method B in Table 2. The foaming and curing speed of the foamable phenolic resin composition containing lignin applied to the lower surface material (Comparative Example 1 described later) was equivalent to that of the foamable phenolic resin composition not containing lignin.

(Comparative Example 1)
A phenolic resin foam laminate of Comparative Example 1 was produced in the same manner as in Example 1, except that lignin was not mixed into the phenolic resin composition. The water content of the phenolic resin composition was 3.73% by mass. The foaming and curing speed of the foamable phenolic resin composition supplied onto the lower surface material was such that a foam laminate was obtained that was sufficiently cured to maintain sufficient productivity in the commercial production of phenolic resin foams.

(Comparative Example 2)
A phenolic resin foam laminate of Comparative Example 2 was produced in the same manner as in Example 1, except that the lignin was changed to a kraft lignin with a median diameter of 23.7 μm and a moisture content of 34.6% by mass without drying. The moisture content of the lignin-containing phenolic resin composition after concentration was 5.94% by mass. In addition, the foaming and curing speed of the foamable phenolic resin composition containing lignin supplied onto the lower surface material was reduced compared to the foaming and curing speed of the foamable phenolic resin composition not containing lignin (Comparative Example 1), and an insufficiently cured foam was obtained. Therefore, after the post-curing process, the foam was further cured at 110° C. for 4 hours to obtain a sufficiently cured foam.

(Comparative Example 3)
A phenolic resin foam laminate of Comparative Example 3 was produced in the same manner as in Example 1, except that 13.7% by mass of water was added to 100 parts by mass of the surfactant-containing phenolic resin composition, and the water content of the concentrated lignin-containing phenolic resin composition was 15.70% by mass. The foaming and curing speed of the lignin-containing foamable phenolic resin composition supplied onto the lower surface material was reduced compared to the foaming and curing speed of the lignin-free foamable phenolic resin composition (Comparative Example 1), resulting in an insufficiently cured foam. Therefore, the foam was further cured at 110°C for 4 hours after the post-curing step to obtain a sufficiently cured foam.

The types of lignin used in Examples 1 to 13 and Comparative Examples 2 to 3 are shown in Table 1. In addition, the above-mentioned measurements and evaluation tests were performed on Examples 1 to 13 and Comparative Examples 1 to 3. The measurement and evaluation results are shown in Tables 2 and 3.

The phenolic resin foam according to the present invention can maintain the foaming and curing time even in the case of a phenolic resin foam containing lignin by appropriately adjusting the water content of the phenolic resin composition to which lignin has been added, and can be produced without reducing productivity. Furthermore, the foaming inhibition caused by water can be suppressed, and fine cells can be maintained, so that even in the case of a phenolic resin foam containing lignin, the thermal conductivity can be maintained, and the heat insulating performance can be maintained. In addition, by grinding lignin powder and adding finely divided lignin having a small particle size, the destruction of cells caused by coarse particles of the lignin powder can be reduced, and fine cells can be maintained, so that even in the case of a phenolic resin foam containing lignin, the thermal conductivity can be maintained, and the heat insulating performance can be maintained. In addition, by using a plant-derived material, it is possible to provide a bio-based phenolic resin foam.

Claims (7)

1. A phenolic resin foam having a thermal conductivity of 0.0240 W/(m K) or less in a 23° C. environment, wherein in an ion chromatogram obtained by subjecting gas components generated by heating at 600° C. to gas chromatography-mass spectrometry, the total X (X=A+B+C) of the area A derived from dihydroxybenzene, the area B derived from dihydroxytoluene, and the area C derived from dihydroxyxylene, which are pyrolysis products, is a ratio of an area Y (Z=X/Y) to an area Y of the pyrolysis product exhibiting a structure derived from urea crosslinking, falls within the range of the following formula (1):
   0.035≦Z≦0.715 (1)
2. The phenolic resin foam according to claim 1, having a density of 10 kg/m3 or ^more and 50 kg/m3 ^or less.
3. The phenolic resin foam according to claim 1 or 2, having an average bubble diameter of 70 μm or more and 250 μm or less.
4. The phenolic resin foam according to claim 1 or 2, which contains either a hydrofluoroolefin, a hydrocarbon, or a chlorinated hydrocarbon.
5. The phenolic resin foam according to claim 1 or 2, which is provided with a surface material on at least one of the surfaces of the phenolic resin foam and the back surface of the surface.
6. A method for producing a phenolic resin foam laminate, comprising foaming and curing a foamable phenolic resin composition, comprising:
   In order to obtain the foamable phenolic resin composition, the method includes at least one of a step of adding lignin to phenols, a step of adding lignin during synthesis of a phenolic resin, a step of adding lignin to a phenolic resin, and a step of adding lignin to a phenolic resin composition;
   The moisture content of the lignin is 34.0% or less,
   The water content of the lignin-containing phenolic resin composition in the foamable phenolic resin composition is 1.5 mass% or more and 6.5 mass% or less.
7. The method according to claim 6, wherein the lignin powder added in the step of adding lignin has a median diameter of 0.1 μm or more and 300 μm or less.