JP7604223B2 - Phenolic resin foam, its manufacturing method and heat insulating material containing same - Google Patents

Description

This relates to phenolic resin foam, its manufacturing method, and insulation materials containing the same.

The insulation material contains thermosetting foam, and by installing it on the walls of a building to prevent heat transfer, it reduces the effect of external temperature changes on the building's internal temperature, making it possible to maintain a constant indoor temperature using less energy.

Thermosetting foam is a cured product of a foamable composition, which contains a curing agent that can cure the foam layer to impart an appropriate closed cell ratio and mechanical properties. Meanwhile, phenolic resin foam containing a curing agent is known to have acidity, but such highly acidic phenolic resin foam may have a problem in that if it is exposed to water, such as rainwater, during use, highly acidic extractables are released from the foam, corroding surrounding metal materials.

For this reason, it is possible to neutralize the acidity of the thermosetting foam by adding a basic inorganic filler to the foaming composition, but this causes a problem that the basic inorganic filler will pre-neutralize with the curing agent, reducing the foaming performance, which in turn increases the thermal conductivity.

The objective of the present invention is to provide a phenolic resin foam that has low acidity of pH 4 or more, has a uniform thickness, and has excellent physical properties such as durability and thermal conductivity.

Another object of the present invention is to provide a method for producing the phenolic resin foam.

Yet another object of the present invention is to provide an insulating material containing the phenolic resin foam.

Means to solve the problem

In one embodiment of the present invention, a phenolic resin foam is provided that is a thermosetting product of a foamable composition containing a phenolic resin, a foaming agent, and a curing agent, and has a pH of 4 or more.

In another embodiment of the present invention, a method for producing a phenolic resin foam is provided, the method comprising the steps of: preparing a foamable composition including a phenolic resin, a foaming agent, and a curing agent; and applying heat to the foamable composition to foam and cure it.

In yet another embodiment of the present invention, a thermal insulation material including the phenolic resin foam is provided.

The phenolic resin foam has low acidity of pH 4 or more, and can achieve excellent physical properties such as durability and thermal conductivity with a uniform thickness.

2 is a scanning electron microscope (SEM) image of a phenolic resin foam according to an embodiment of the present invention; FIG. 2 is a schematic diagram showing a method for measuring the thickness deviation of the phenolic resin foam of the present invention.

The advantages and features of the present invention, as well as the methods for achieving them, will become clearer with reference to the following examples. However, the present invention is not limited to the examples disclosed below, and may be embodied in various different forms. However, the examples are provided to fully disclose the present invention and to fully inform those skilled in the art of the present invention of the scope of the invention, and the present invention is defined only by the scope of the claims.

In the drawings, the thickness of multiple layers and regions is exaggerated to clearly show them. Also, in the drawings, the thickness of some layers and regions is exaggerated to facilitate explanation. The same reference symbols throughout the specification refer to the same components.

In addition, when a part such as a layer, film, region, plate, etc. is said to be "on" or "above" another part, this includes not only the case where it is "directly above" another part, but also the case where there is another part in between. Conversely, when a part is said to be "directly above" another part, it means that there is no other part in between. In addition, when a part such as a layer, film, region, plate, etc. is said to be "under" or "below" another part, this includes not only the case where it is "directly below" another part, but also the case where there is another part in between. Conversely, when a part is said to be "directly below" another part, it means that there is no other part in between.

In one embodiment of the present invention, a phenolic resin foam is provided that is a thermosetting product of a foamable composition containing a phenolic resin, a foaming agent, and a curing agent, and has a pH of 4 or more.

Generally, thermosetting foams contain a curing agent, and the foam layer can be cured to impart appropriate closed cell ratio and mechanical properties. However, thermosetting foams containing a curing agent, such as phenolic resin foams, contain a highly acidic curing agent, which can cause problems such as a low pH of the thermosetting foam and corrosion of surrounding metal materials due to the highly acidic thermosetting foam. In addition, if the content of the curing agent is reduced to produce a low-acid thermosetting foam, it becomes difficult to adjust the foaming and curing performance, the balance is broken, and problems such as poor appearance of the thermosetting foam and high thermal conductivity can occur. In addition, if a phenolic resin with high reactivity is used or the curing temperature is increased to improve this, it can be difficult to produce a thermosetting foam with a uniform thickness of a certain level.

The phenolic resin foam of the present invention comprises a thermosetting product of a foamable composition comprising a phenolic resin, a foaming agent, and a curing agent, and the composition can be adjusted to have a uniform thickness, excellent durability and thermal conductivity, and low acidity of pH 4 or more. Specifically, the pH of the phenolic resin foam may be 4 to 7, 4.5 to 7, or 5 to 6. The phenolic resin foam has a high closed cell ratio, a uniform thickness, excellent compressive strength, and thermal conductivity, and exhibits excellent insulation performance. In addition, by exhibiting low acidity in the pH range, the phenolic resin foam can be produced more stably, and it does not corrode surrounding metals, etc., so it can be used more stably for a long period of time.

The foamable composition contains a phenolic resin. The phenolic resin is obtained by reacting phenol with formaldehyde, and may contain, for example, a resol-based phenolic resin.

The foamable composition may contain the phenolic resin in an amount of about 30% to about 90% by weight. By containing the phenolic resin in an amount within this range, foam cells can be stably formed and excellent thermal conductivity can be realized. Specifically, if the phenolic resin is contained in an amount less than this range, it is difficult to form foam cells and the thermal conductivity is high, and if it exceeds this range, the proportion of other additives, etc. becomes relatively low, which may cause defects in the shape of the foam cells or in the foaming process.

The phenolic resin may have a viscosity of about 1,000 cps to about 30,000 cps, specifically about 2,000 cps to about 10,000 cps, or more specifically about 3,000 cps to about 7,000 cps, at a temperature of about 40° C. The viscosity may be measured using a Brookfield viscometer.

The foamable composition contains a phenolic resin having a viscosity in the above range, and the foaming performance can be suitably adjusted, so that foam cells are well formed, the closed cell rate is improved, and excellent thermal conductivity can be imparted. Specifically, if the viscosity of the phenolic resin is below the above range, loss of foaming gas may occur in the early stages of foaming, which may increase thermal conductivity and reduce insulation. In addition, if the viscosity exceeds the above range, the curing speed becomes faster than the foaming speed, and foam cells having an appropriate size are not well formed, which may cause a problem that the foam cannot be formed to a desired thickness of a certain level or more.

In addition, the phenolic resin may have a moisture content of about 5% by weight or more, specifically, about 5% to about 30% by weight. More specifically, it may be about 7% to about 23% by weight. The moisture content may be measured by the Karl Fischer Titration method. The phenolic resin may have a moisture content within the above range, thereby realizing excellent workability and excellent heat insulation. Specifically, if the moisture content of the phenolic resin is out of the above range and is too low, the foamable composition may not be smoothly blended with other components, making process control difficult, and if the moisture content is too high, the heat insulation may decrease and the adhesiveness of the thermosetting foam may decrease. Therefore, the phenolic resin foam may be difficult to firmly adhere to a surface material, etc., by a lamination method.

The phenolic resin may not contain a urea bond. This prevents moisture from being generated by the urea-formaldehyde reaction during the polymerization process of the phenolic resin, making it easier to adjust the viscosity and moisture of the foamable composition.

The foamable composition includes a curing agent. The curing agent may include one acid curing agent selected from the group consisting of toluenesulfonic acid, xylenesulfonic acid, benzenesulfonic acid, phenolsulfonic acid, ethylbenzenesulfonic acid, styrenesulfonic acid, naphthalenesulfonic acid, and combinations thereof. The foamable composition includes the curing agent and may exhibit suitable crosslinking, hardening, and foaming properties.

The foamable composition may contain the curing agent in an amount of about 3 parts by weight to about 15 parts by weight based on 100 parts by weight of the phenolic resin. For example, the curing agent may be contained in an amount of about 5 parts by weight to about 12 parts by weight or about 5 parts by weight to about 10 parts by weight based on 100 parts by weight of the phenolic resin. The foamable composition contains the curing agent in such a low amount as described above, and can impart low acidity to the phenolic resin foam, and can provide excellent insulation performance by realizing uniform thickness, excellent compressive strength, and low thermal conductivity.

Specifically, if the content of the hardener is less than the range, the pH may be higher, but there is a problem that the performance as a heat insulating material is significantly reduced, and if the content exceeds the range, there is a problem that the acidity becomes high, i.e., the pH becomes low.

The foamable composition includes a foaming agent. The foaming agent may include one selected from the group consisting of hydrofluoroolefin (HFO) compounds, hydrocarbon compounds, and combinations thereof.

The foamable composition may contain a foaming agent having a vapor pressure of about 20 kPa to about 110 kPa at 20°C by adjusting the type and content of the foaming agent, specifically, a foaming agent having a vapor pressure of about 30 kPa to about 100 kPa, more specifically, about 33 kPa to about 85 kPa. The vapor pressure of the foaming agent means the inherent vapor pressure of the foaming agent at 20°C. The vapor pressure of the foaming agent can be measured by the static method of KS M 1071-3. When the foaming agent is a mixture of two or more foaming agents, the vapor pressure of the foaming agent (Pm) means a value calculated using the following relational expression 1.

[Relational expression 1] P _m = (m ₁ P1 + m ₂ P ₂ +..m _x P _x )/(m ₁ + m ₂ +.. m _x )
P _m : Vapor pressure of the entire mixture m _x : Number of moles of blowing agent x itself contained in the mixture P _x : Vapor pressure specific to blowing agent x

In general, when the content of the curing agent in the foamable composition is reduced, the thermosetting foam can be given low acidity. However, as the content of the curing agent decreases, the foaming amount and foaming performance decrease, the balance with the curing performance is broken, and problems such as the thickness of the thermosetting foam becoming non-uniform, the compressive strength decreasing, and the thermal conductivity increasing can occur.

The foamable composition contains a foaming agent having a vapor pressure in the above range, and can impart improved foaming performance, and can impart a high closed cell ratio, uniform thickness, excellent compressive strength, and excellent thermal conductivity to the phenolic resin foam having low acidity.

Specifically, if the vapor pressure of the foaming agent is below the above range, foaming does not occur sufficiently, making it difficult to obtain a phenolic resin foam of the specified thickness, and there may be a problem of large thickness deviations at different positions in the phenolic resin foam. If the vapor pressure of the foaming agent exceeds the above range, foaming occurs too quickly, reducing the closed cell ratio, and rupturing the foam cells of the phenolic resin foam, reducing physical strength and increasing thermal conductivity.

The hydrofluoroolefin-based compound may be, for example, a chlorinated hydrofluoroolefin-based compound, a non-chlorinated hydrofluoroolefin-based compound, or may include all of these.

The hydrofluoroolefin-based compound may be any of the known types in this technical field, for example, trans 1-chloro-3,3,3-trifluoropropene (trans CF3CH=CClH), cis 1-chloro-3,3,3-trifluoropropene (cis CF3CH=CClH), trans 1-chloro-2,3,3-trifluoropropene (trans CHF2CF=CClH), cis 1-chloro-2,3,3-trifluoropropene (cis CHF2CF=CClH), trans 1-chloro-1,3,3-trifluoropropene (trans CHF2CH=CClF), cis 1-chloro-1,3,3-trifluoropropene (cis CHF2CH=CClF), trans 2-chloro-1,3,3-trifluoropropene (trans CHF2CCl=CHF), cis 2-chloro-1,3,3-trifluoropropene (cis CHF2CCl=CHF), trans 2-chloro-1,1,3-trifluoropropene (trans CH2FCCl=CF2), cis 2-chloro-1,1,3-trifluoropropene (cis CH2FCCl=CF2), trans 3-chloro-1,2,3-trifluoropropene (trans CHFCilCF=CFH), cis 3-chloro-1,2,3-trifluoropropene (cis CHFCilCF=CFH), trans 3-chloro-1,1,2-trifluoropropene (trans CH2ClCF=CF2), cis 3-chloro-1,1,2-trifluoropropene (cis CH2ClCF=CF2), trans 3-chloro-2,3,3-trifluoropropene (trans CF2ClCF=CH2), cis 3-chloro-2,3,3-trifluoropropene (cis CF2ClCF=CH2) and other monochlorotrifluoropropenes; trifluoropropenes such as 2,3,3-trifluoropropene (CHF2CF=CH2), 1,1,2-trifluoropropene (CH3CF=CF2), 1,1,3-trifluoropropene (CH2FCH=CF2), and 1,3,3-trifluoropropene (CHF2CH=CHF); tetrafluoropropenes such as 1,2,3,3-tetrafluoro-1-propene, 2,3,3,3-tetrafluoro-1-propene, 1,3,3,3-tetrafluoro-1-propene, 1,1,2,3-tetrafluoro-1-propene, 1,1,3,3-tetrafluoro-1-propene, and 1,2,3,3-tetrafluoro-1-propene; 1,2,3,3,3-pentafluoro-1-propene, 1,1,3,3,3-pentafluoro-1-propene, pentafluoropropenes such as 1,1,2,3,3-pentafluoro-1-propene; 2,3,3,4,4,4-hexafluoro-1-butene, 1,1,1,4,4,4-hexafluoro-2-butene, 1,3,3,4,4,4-hexafluoro-1-butene, 1,2,3,4,4,4-hexafluoro-1-butene, 1,2,3,3,4,4-hexafluoro-1-butene, 1,1,2 , 3,4,4-hexafluoro-2-butene, 1,1,1,2,3,4-hexafluoro-2-butene, 1,1,1,2,3,3-hexafluoro-2-butene, 1,1,1,3,4,4-hexafluoro-2-butene, 1,1,2,3,3,4-hexafluoro-1-butene, and other hexafluorobutenes, and combinations thereof, may be included.

The hydrocarbon-based compound may contain a hydrocarbon having 1 to 6 carbon atoms, and may contain, for example, a chlorinated hydrocarbon compound, a non-chlorinated hydrocarbon compound, or all of these.

The hydrocarbon compound may include at least one selected from the group consisting of dichloroethane, propyl chloride, isopropyl chloride, butyl chloride, isobutyl chloride, pentyl chloride, isopentyl chloride, n-butane, isobutane, n-pentane, isopentane, cyclopentane, n-hexane, and combinations thereof, but is not limited thereto.

The blowing agent may be a mixture of two or more of the blowing agents. Specifically, the mixed blowing agent contains a hydrofluoroolefin (HFO) compound, and can provide excellent foaming performance even with a low calorific value. For example, the blowing agent may be a mixture of one hydrofluoroolefin compound selected from the group consisting of 1-chloro-3,3,3-trifluoropropene (CF3CH=CClH), 1,1,1,4,4,4-hexafluoro-2-butene, and combinations thereof, and one hydrocarbon compound selected from the group consisting of cyclopentane, isopentane, n-pentane, n-hexane, n-butane, and combinations thereof.

The foaming agent may be included in a total content of about 5 parts by weight to about 15 parts by weight based on about 100 parts by weight of the phenolic resin. By including the foaming agent in this range, it is possible to provide the phenolic resin foam with low acidity, uniform thickness, excellent compressive strength, and excellent thermal conductivity, while exhibiting excellent foaming performance even with a low heat generation.

Specifically, if the foaming agent content is less than the above range, there may be a problem that foaming does not occur due to an insufficient amount of vaporized foaming agent, or that foaming does not occur sufficiently, resulting in a failure to achieve the specified thickness or a large deviation in thickness at different positions in the phenolic resin foam. If the foaming agent content exceeds the above range, there may be a problem that an excessive amount of foaming agent vaporizes, making it difficult to adjust the vapor pressure of the foaming agent, or that the foaming pressure becomes too high, causing the foam cells of the phenolic resin foam to break, resulting in a low closed cell ratio, a decrease in physical strength, and an increase in thermal conductivity.

The foamable composition may further include one crosslinking agent selected from the group consisting of resorcinol, cresol, saligenin, p-methylolphenol, and combinations thereof.

In general, when the content of the curing agent in the foamable composition is reduced, the thermosetting foam can be given low acidity. However, as the content of the curing agent is reduced, the curing performance decreases, and the balance with the foaming performance is broken, which can cause phenomena such as foam cells breaking, and problems such as cracks appearing in the thermosetting foam, making the thickness uneven and increasing the thermal conductivity.

The foamable composition further contains the crosslinking agent in addition to the curing agent, and while maintaining the low acidity of the phenolic resin foam, it imparts excellent crosslinking and curing performance, making the thickness of the phenolic resin foam uniform and imparting excellent durability such as compressive strength and excellent thermal conductivity.

Specifically, the foamable composition may contain the curing agent and the crosslinking agent in a weight ratio of about 6:4 to about 3:7. For example, the foamable composition may contain the curing agent and the crosslinking agent in a weight ratio of about 6:4 to 4:9 or about 5:6 to 4:9. If the content of the crosslinking agent is less than the above range, the crosslinking and curing reaction may be insufficient, resulting in high thermal conductivity and low compressive strength. Also, if the content of the crosslinking agent exceeds the above range, the foam may be cured without sufficient foaming, resulting in rupture of foam cells, low closed cell ratio, large thickness deviation at different positions of the phenolic resin foam, and high thermal conductivity.

The phenolic resin foam may have a mass ratio of carbon to sulfur (C/S) of 25 to 250 at the vertex of the cell as measured by energy dispersive X-ray analysis (EDX).

Figure 1 is a scanning electron microscope (SEM) photograph of a phenolic resin foam according to an embodiment of the present invention. As shown in Figure 1, the cells contained in the phenolic resin foam have cell walls 10 and support struts 20 formed at the points where the cell walls meet, and the support struts 20 form the skeleton of the cells. In addition, the intersections where the support struts 20 meet are defined as cell vertices 30.

The cross section of the phenolic resin foam at the middle of the width, length and height, i.e., the center part, for example, a cross section of a panel-type foam bisected in the thickness direction, was magnified 200 times with a scanning electron microscope (SEM), and only C, O and S elements were selected at the vertex of the cell of the cross section and the proportions of these three elements were measured with EDX (manufacturer Horiba, EMAX EX-250, accelerating voltage 15 kv).

Specifically, n cells that were not adjacent to each other were selected based on any one of the cells included in the cross section, and the ratios of C, O, and S elements at one vertex included in each of the cells were measured. In addition, the mass ratio of carbon to sulfur (C/S) was measured by setting the sum of the ratios of C, O, and S elements measured at the vertex of each cell as 100%. The mass ratio of carbon to sulfur (C/S) means the sum of the C/S values at one vertex included in the 1st to nth cells divided by n. That is, the mass ratio of carbon to sulfur (C/S) can be calculated using the following Equation 1.

In this case, n is an integer between 7 and 10. Preferably, n is between 9 and 10 or n is 10.

The phenolic resin foam is a thermoset of the foamable composition, and the foamable composition may be adjusted so that the vertex of the cell has a carbon to sulfur mass ratio (C/S) of about 25 to about 250, or about 50 to about 150, or about 69 to about 123, as measured by EDX.

The sulfur may be an element derived from the curing agent, and the phenolic resin foam may have a mass ratio of carbon to sulfur (C/S) in the range described above, compared to the carbon (C) contained in the phenolic resin foam, which is a thermoset product of the foamable composition containing the foaming agent.

If the mass ratio of carbon to sulfur (C/S) is less than the above range, an acidic foam with high acidity and low pH may be formed, whereas if it exceeds the above range, curing may not occur sufficiently during the foaming process, resulting in low physical strength of the phenolic resin foam, cracks on the surface, uneven thickness, low compressive strength, and high thermal conductivity.

The phenolic resin foam may have a mass ratio of oxygen to sulfur (O/S) of about 5 to about 60, measured by EDX at the vertices of the cells. The mass ratio of oxygen to sulfur (O/S) means the sum of the O/S values of one vertex included in the 1st to nth cells divided by n. That is, the mass ratio of oxygen to sulfur (O/S) can be calculated using the following Equation 2.

In this case, n is an integer between 7 and 10. Preferably, n is between 9 and 10 or n is 10.

The phenolic resin foam is a thermoset of the foamable composition, and the foamable composition may be adjusted so that the mass ratio of oxygen to sulfur (O/S) measured by EDX at the vertices of the cells is about 5 to about 60, or about 10 to about 50, or about 19 to about 33.

The sulfur is an element derived from the curing agent, and the phenolic resin foam may have a mass ratio of oxygen to sulfur (O/S) in the above range, compared to the oxygen (O) contained in the phenolic resin foam, which is a thermoset of the foamable composition containing the phenolic resin, a specific curing agent, a crosslinking agent, etc.

If the mass ratio of oxygen to sulfur (O/S) is below the above range, curing will occur without sufficient foaming, and during this process, the acidity (pH) of the phenolic resin foam may be low, the thickness may be non-uniform, and the thermal conductivity may be high. If the mass ratio exceeds the above range, the curing performance may be insufficient, causing the physical strength of the phenolic resin foam to decrease and the thermal conductivity to increase.

The average thickness of the phenolic resin foam may be about 70 mm to about 300 mm. By having an average thickness within this range, the phenolic resin foam does not excessively increase the total thickness of the building insulation material including the phenolic resin foam, and can realize a sufficiently excellent level of insulation. Specifically, if the average thickness of the phenolic resin foam is less than this range, there is a problem that the thermal conductivity is low and it cannot fulfill its role as a building insulation material, and if it exceeds this range, heat generated during the curing process may accumulate in the inner center of the foam, preventing the formation of a cell structure and reducing thermal conductivity.

The phenolic resin foam may have a thickness deviation of about 5% or less, specifically about 0.1% to about 5%, according to the following formula 3:

[Formula 3]
Thickness deviation (T _d , %)=(T _max −T _min )/T _avg ×100

In the above Equation 3, _Tmax means the maximum thickness measured on the foam for which the thickness deviation is to be measured, _Tmin means the minimum thickness measured on the foam, and _Tavg means the average thickness measured on the foam.

The phenolic resin foam has a thickness deviation within the above range and is found to have excellent thickness uniformity, thereby exhibiting excellent thermal conductivity, more effectively improving long-term insulation, and providing excellent processability and workability when applied to a specific product. For example, the phenolic resin foam may have a thickness deviation of about 0.1% to about 3%, or 0.1% to 2.4%.

The phenolic foam may have a thermal conductivity of about 0.0160 W/m·K to about 0.0220 W/m·K measured through the thickness at a temperature of about 20° C. according to KS L 9016. For example, the phenolic foam may have a thermal conductivity of about 0.0164 W/m·K to about 0.0210 W/m·K, about 0.0164 W/m·K to less than about 0.020 W/m·K, or about 0.0164 W/m·K to about 0.0194 W/m·K.

Normally, the thicker the foam, the lower the thermal conductivity measured in the thickness direction. As mentioned above, the phenolic resin foam has a sufficiently large thickness and does not reduce thermal conductivity, so it can maintain excellent thermal insulation.

The density of the phenolic resin foam may be about 20 kg/m3 to about 50 kg/m3. By having a density in this range, the phenolic resin foam is easy to handle on-site and can achieve excellent physical strength and excellent insulation performance.

The phenolic resin foam may have a compressive strength of about 100 kPa to about 300 kPa according to KS M ISO 844. The phenolic resin foam may be a cured product of the foamable composition produced by adding the phenolic resin to the curing agent, the foaming agent, the crosslinking agent, etc., and may have a compressive strength in the above range. If the compressive strength of the phenolic resin foam is less than the above range, the phenolic resin foam may be easily deformed in appearance when handled, such as when cut or applied, and may be easily damaged due to use of the phenolic resin foam, resulting in problems with long-term durability. If the compressive strength exceeds the above range, the density of the phenolic resin foam may increase and problems with high thermal conductivity may occur.

The phenolic resin foam may have a closed cell ratio of about 85% or more. The phenolic resin foam is made up of small ham-comb-shaped cells, and the percentage of closed cells among the cells is called the closed cell ratio. The higher the closed cell ratio, the better the insulation, and if the closed cell ratio is less than about 85%, a certain level of insulation cannot be ensured. There is no upper limit to the closed cell ratio, but the phenolic resin foam may have a closed cell ratio of about 99%.

Another embodiment of the present invention provides a method for producing a phenolic resin foam, the method comprising the steps of: preparing a foamable composition including a phenolic resin, a foaming agent, and a curing agent; and applying heat to the foamable composition to foam and cure it.

The above-mentioned phenolic resin foam can be produced by the above-mentioned manufacturing method.

In the above manufacturing method, a foamable composition containing a phenolic resin, a foaming agent, and a curing agent is prepared. Specific details regarding the foamable composition are as described above.

Specifically, the foamable composition can be produced by first mixing the phenolic resin and the foaming agent, and then adding a curing agent to the mixture. In this case, if the foamable composition further contains a crosslinking agent, the crosslinking agent may be added to the mixture and mixed together, and then the curing agent may be added.

The above manufacturing method also includes a step of applying heat to the prepared foamable composition to foam and harden it. The foamable composition can be foamed and hardened simultaneously, and in this case, either foaming or hardening can be started first, or both can be started simultaneously.

The foaming and curing can be carried out, for example, under temperature conditions of about 50°C to about 90°C. The foaming and curing can be carried out for about 2 minutes to about 20 minutes, but is not limited thereto, and may be suitably different depending on the purpose and application of the invention.

The foamable composition may be, for example, foamed and cured in a predetermined mold, or may be, for example, foamed and cured while being injected or ejected between both surface materials, but is not limited thereto. In this way, the above-mentioned phenolic resin foam can be produced.

Yet another embodiment of the present invention provides an insulating material comprising the phenolic resin foam.

The phenolic resin foam is a low-acid phenolic resin foam with a pH of 4 or more, and can be used, for example, as a building insulation material. Even when exposed to water such as rainwater, it does not corrode surrounding metal materials, and can simultaneously meet the high thickness standard, excellent durability, and excellent thermal conductivity required for a building insulation material.

The building insulation material may further include a surface material on one or both sides of the phenolic resin foam, and the surface material may be of a type known in the art, such as, but not limited to, woven fabric, nonwoven fabric, cloth, metal foil such as aluminum, paper, etc. derived from organic or inorganic substances.

Specific examples of the present invention are presented below. However, the examples described below are merely intended to specifically illustrate or explain the present invention, and should not be construed as limiting the present invention.

<Examples and Comparative Examples>
Example 1
A resol-based phenolic resin having a viscosity of 3,900 cps under a temperature condition of 40° C. was prepared at a temperature of 20° C. A resin mixture was prepared by mixing 100 parts by weight of the resol-based phenolic resin with trans-1-chloro-3,3,3-trifluoropropene (trans CF3CH=CClH) and cyclopentane in a weight ratio of 7:3, 10 parts by weight of a foaming agent having a vapor pressure of about 74 kPa at 20° C., 3 parts by weight of a polyoxyethylene sorbitan ester surfactant, and 36 parts by weight of a crosslinking agent mixture (polyester polyol and resorcinol) in which resorcinol was mixed with polyester polyol in a weight ratio of 5:5. In addition, toluene sulfonic acid (p-toluene sulfonic acid) was prepared in an amount of 8 parts by weight based on 100 parts by weight of the resol-based phenolic resin, and mixed with water in a weight ratio of 8:2, and then added to the resin mixture to prepare a foamable composition. The foamable composition was kneaded at 2000 rpm to form a white foam-like slurry. The white foam was then filled into a 300×300×90 mm metal mold to a density of 40 kg/ ^m3 , heated in an oven at 70° C. for 10 minutes, and the mold was then separated to finally prepare a phenolic resin foam.

Example 2
A phenolic resin foam was prepared in the same manner as in Example 1, except that 1,1,1,4,4,4-hexafluoro-2-butene having a vapor pressure of about 60 kPa at 20° C. was used as a foaming agent, 24 parts by weight of a crosslinking agent mixture (polyester polyol and resorcinol) in which polyester polyol and resorcinol were mixed in a weight ratio of 5:5 relative to 100 parts by weight of the resol-based phenolic resin, and 10 parts by weight of toluene sulfonic acid was prepared relative to 100 parts by weight of the resol-based phenolic resin, and then mixed with water in a weight ratio of 8:2 and then added to prepare a foamable composition.

Example 3
A phenolic resin foam was prepared in the same manner as in Example 1, except that a foaming agent having a vapor pressure of about 74 kPa at 20° C. was used, and a crosslinking agent mixture (polyester polyol and resorcinol) was prepared by mixing polyester polyol and resorcinol in a weight ratio of 5:5 with respect to 100 parts by weight of the resol-based phenolic resin, and toluene sulfonic acid was prepared in an amount of 12 parts by weight with respect to 100 parts by weight of the resol-based phenolic resin, and the mixture was mixed with water in a weight ratio of 8:2 and then added to prepare a foamable composition.

Example 4
A phenolic resin foam was prepared in the same manner as in Example 1, except that a foamable composition was prepared by mixing trans-1-chloro-3,3,3-trifluoropropene (trans CF3CH=CClH) and cyclopentane in a weight ratio of 1:9 and using a foaming agent having a vapor pressure of about 39 kPa at 20°C.

Example 5
A phenolic resin foam was prepared in the same manner as in Example 1, except that a foaming agent having a vapor pressure of about 37 kPa at 20° C. was used, which was a mixture of trans-1-chloro-3,3,3-trifluoropropene (trans CF3CH═CClH) and cyclopentane in a weight ratio of 5:95, and a crosslinking agent mixture (polyester polyol and resorcinol) in which polyester polyol and resorcinol were mixed in a weight ratio of 5:5 per 100 parts by weight of the resol-based phenolic resin was used, and toluene sulfonic acid was prepared in an amount of 12 parts by weight per 100 parts by weight of the resol-based phenolic resin, and then mixed with water in a weight ratio of 8:2 and then added to prepare a foamable composition.

Example 6
A phenolic resin foam was prepared in the same manner as in Example 1, except that a foaming agent having a vapor pressure of about 74 kPa at 20° C. was used, which was a mixture of trans-1-chloro-3,3,3-trifluoropropene (trans CF3CH═CClH) and cyclopentane in a weight ratio of 7:3, and a crosslinking agent mixture (polyester polyol and resorcinol) in which polyester polyol and resorcinol were mixed in a weight ratio of 5:5 per 100 parts by weight of the resol-based phenolic resin was used, and toluene sulfonic acid was prepared in an amount of 15 parts by weight per 100 parts by weight of the resol-based phenolic resin, and then mixed with water in a weight ratio of 8:2 and then added to prepare a foamable composition.

Example 7
A phenolic resin foam was prepared in the same manner as in Example 1, except that a foaming composition was prepared by mixing trans-1-chloro-3,3,3-trifluoropropene (trans CF3CH=CClH) and cyclopentane in a weight ratio of 7:3 and having a vapor pressure of about 74 kPa at 20° C., using 8 parts by weight of a foaming agent, and mixing polyester polyol and resorcinol in a weight ratio of 5:5 with respect to 100 parts by weight of the resol-based phenolic resin (15 parts by weight of a crosslinking agent mixture (polyester polyol and resorcinol) with polyester polyol in a weight ratio of 5:5 with respect to 100 parts by weight of the resol-based phenolic resin, and preparing toluene sulfonic acid in an amount of 5 parts by weight with respect to 100 parts by weight of the resol-based phenolic resin, and mixing it with water in a weight ratio of 8:2 and then adding it.

Example 8
A phenolic resin foam was prepared in the same manner as in Example 1, except that a foaming agent having a vapor pressure of about 37 kPa at 20° C. was used, which was a mixture of trans-1-chloro-3,3,3-trifluoropropene (trans CF3CH═CClH) and cyclopentane in a weight ratio of 5:95, and a crosslinking agent mixture (polyester polyol and resorcinol) in which polyester polyol and resorcinol were mixed in a weight ratio of 5:5 per 100 parts by weight of the resol-based phenolic resin was used, and toluene sulfonic acid was prepared in an amount of 7 parts by weight per 100 parts by weight of the resol-based phenolic resin, and then mixed with water in a weight ratio of 8:2 and then added to prepare a foamable composition.

Comparative Example 1
A phenolic resin foam was prepared in the same manner as in Example 1, except that toluene sulfonic acid (p-toluene sulfonic acid) was prepared in an amount of 25 parts by weight based on 100 parts by weight of the resol-based phenolic resin, mixed with water in a weight ratio of 8:2, and added to the resin mixture not including the crosslinker mixture to prepare a foamable composition.

Comparative Example 2
A phenolic resin foam was prepared in the same manner as in Example 1, except that toluene sulfonic acid (p-toluene sulfonic acid) was prepared in an amount of 12 parts by weight based on 100 parts by weight of the resol-based phenolic resin, mixed with water in a weight ratio of 8:2, and added to the resin mixture not including the crosslinker mixture to prepare a foamable composition.

Comparative Example 3
A phenolic resin foam was manufactured in the same manner as in Example 1, except that a foaming composition was manufactured using 8 parts by weight of trans-1-chloro-3,3,3-trifluoropropene (trans CF3CH=CClH) alone having a vapor pressure of about 154 kPa at 30° C., 33.2 parts by weight of a crosslinking agent mixture (polyester polyol and resorcinol) in which polyester polyol and resorcinol were mixed in a weight ratio of 5:5 relative to 100 parts by weight of the resol-based phenolic resin, and 5 parts by weight of toluene sulfonic acid was prepared relative to 100 parts by weight of the resol-based phenolic resin, which was then mixed with water in a weight ratio of 8:2 and then added to the mixture.

<Evaluation>
Experimental Example 1: EDX (energy dispersive X-ray analysis)
The center part of the phenolic resin foam of the examples and comparative examples was cut into a test piece having a size of 5 mm x 5 mm and a thickness (h = 90 mm). In addition, a cut was made in the center part (h/2) of the test piece, and the test piece was placed in liquid nitrogen, and a force was applied to both ends of the test piece so that the cut center part was cut. For this purpose, a test piece having a cross section preserved in liquid nitrogen was prepared. Then, the test piece including the cross section was cut to a thickness of 2 mm, and the test piece preserved in liquid nitrogen was fixed on an SEM mount so that the cross section of the test piece facing upward, and was then PT coated (platinum coated). In addition, the SEM mount on which the test piece was fixed was placed in an SEM, and the screen was magnified to 200 times.

Figure 1 is a scanning electron microscope (FE-SEM, SU8010, Hitachi) photograph of a phenolic resin foam according to one embodiment of the present invention. As shown in Figure 1, the cells contained in the phenolic resin foam have cell walls 10 and support struts 20 formed at the points where the cell walls meet, and the support struts 20 form the skeleton of the cells. In addition, the intersections where the support struts 20 meet are defined as cell vertices 30.

On the vertex of the cell on the SEM screen, only C, O, and S elements were selected and the ratio of these three elements was measured using an EDX (energy dispersive X-ray analysis) (Horiba, EMAX EX-250, acceleration voltage 15 kv). Specifically, based on one arbitrary cell included in the cross section, n cells (n=10) that are not adjacent to each other were selected and the ratio of C, O, and S elements at one vertex included in each of the cells was measured.

The sum of the measured proportions of C, O, and S elements was set to 100%, and the mass ratio of carbon to sulfur (C/S) and the mass ratio of oxygen to sulfur (O/S) were calculated using the following formulas 1 and 2, and the results are shown in Tables 1 and 2 below.

In this case, n is an integer between 7 and 10.

In this case, n is an integer between 7 and 10.

Experimental Example 2: pH
The center of the phenolic foam of each of the examples and comparative examples was cut into a size of 50 mm x 50 mm x 50 mm to prepare a specimen, which was then immersed in 150 ml of distilled water at 20°C to 30°C so that all six sides of the specimen were in contact with the distilled water, sealed, and immersed for 48 hours. The pH of the extract obtained after removing the immersed specimen was measured using a pH meter, and the results are shown in Tables 1 and 2 below.

Experimental Example 3: Thermal conductivity (W/mK)
The phenolic foams of the examples and comparative examples were cut from the center to a thickness of 50 mm from the top and a size of 300 mm x 300 mm to prepare specimens, which were then pretreated by drying at 70° C. for 12 hours. The thermal conductivity of the specimens was measured using a thermal conductivity instrument HC-074-300 (EKO Co., Ltd.) at an average temperature of 20° C. according to the measurement conditions of KS L 9016 (plate heat flow meter measurement method), and the results are shown in Tables 1 and 2 below.

Experimental Example 4: Compressive strength (kPa)
The phenolic foams of the examples and comparative examples were prepared as test pieces with a size of 50 mm x 50 mm and a thickness of 90 mm, and the test pieces were placed between the wide plates of a Universal Testing Machine (LF Plus) manufactured by Lloyd Instruments, and a compression strength test was started at a speed of 10% of the thickness of the test piece/min in the UTM equipment, and the maximum load reached during the reduction in thickness was recorded. The compression strength was measured according to the method of KS M ISO 844 standard, and the results are shown in Tables 1 and 2 below.

Experimental Example 5: Thickness deviation (%)
FIG. 2 is a schematic diagram simply illustrating a method for measuring the thickness deviation of the phenolic resin foam of the present invention.

The phenolic foams of the examples and comparative examples were prepared as test pieces having a size of 300 mm×300 mm and a thickness (90 mm), and then the thicknesses of the test pieces were measured at five points at intervals of 50 mm on each of the horizontal and vertical sides of the test pieces using a sliding caliper tool having an accuracy of 0.1 mm, as shown by the solid lines in Fig. 2. That is, the thicknesses of the test pieces were measured at 20 points on a total of four sides to set T _avg , T _max , and T _min , and the thickness deviation was measured according to the following Equation 3, and the results are shown in Tables 1 and 2 below.

[Formula 3]
Thickness deviation (T _d , %)=(T _max −T _min )/T _avg ×100

In the above formula 3, T _max means the maximum thickness measured for the foam sheet, T _min means the minimum thickness measured, and T _avg means the average thickness measured.

Experimental Example 6: Closed cell ratio (%)
The foams of the Examples and Comparative Examples were measured using a closed cell ratio measuring device (Quantachrome, ULTRAPYC 1200e) according to the KSM ISO 4590 measurement method, and the results are shown in Tables 1 and 2 below.

As shown in Tables 1 and 2, Comparative Example 1, which does not fall within the fixed values of EDX(C/S) and EDX(O/S), shows that the acidity of the phenolic resin foam is too high, and Comparative Example 2 shows that the thermal conductivity and compressive strength are reduced and significant thickness deviation occurs, even though the phenolic resin foam has low acidity. On the other hand, it can be confirmed that the Examples have low acidity of pH 4 or more, and also have uniform thickness and excellent physical properties such as durability and thermal conductivity.

10 Cell wall
20 Strut
30 Cell vertex

Claims (6)

A phenolic resin foam which is a thermosetting product of a foamable composition containing a phenolic resin, a foaming agent, and a curing agent,
The pH is 4 or more,
The phenolic resin foam has a carbon to sulfur mass ratio (C/S) of 25 to 250 as measured by an energy dispersive X-ray analysis (EDX) at a vertex of a cell;
The mass ratio of oxygen to sulfur (O/S) measured at the apex of a cell of the phenolic resin foam by an energy dispersive X-ray analysis (EDX) is 5 to 60;
Compressive strength according to KS M ISO 844 is 100 kPa to 300 kPa;
The foamable composition further comprises a crosslinking agent;
the crosslinking agent further comprises one crosslinking agent selected from the group consisting of resorcinol, cresol, saligenin, p-methylolphenol, and combinations thereof;
the weight ratio of the curing agent to the crosslinking agent is 6:4 to 3:7;
The foamable composition contains 5 to 10 parts by weight of the curing agent relative to 100 parts by weight of the phenolic resin.
Phenolic foam. The vapor pressure of the foaming agent at 20°C is 20 kPa to 110 kPa.
The phenolic foam of claim 1 . The blowing agent includes at least one selected from the group consisting of hydrofluoroolefin (HFO)-based compounds, hydrocarbon-based compounds, and combinations thereof;
The phenolic resin foam according to claim 1 or 2 . The curing agent comprises one selected from the group consisting of toluene sulfonic acid, xylene sulfonic acid, benzene sulfonic acid, phenol sulfonic acid, styrene sulfonic acid, ethylbenzene sulfonic acid, naphthalene sulfonic acid, and combinations thereof;
The phenolic resin foam according to any one of claims 1 to 3. The thickness deviation according to the following formula 3 is 5% or less.
The phenolic foam of claim 1 :
[Formula 3]
Thickness deviation (T _d , %)=( T _max − T _min )/ T _avg ×100
In the above formula 3, _Tmax means the maximum thickness measured for the foam for which the thickness deviation is to be measured, _Tmin means the minimum thickness measured for the foam, and _Tavg means the average thickness measured for the foam. The present invention relates to a phenolic resin foam comprising a phenolic resin foam according to any one of claims 1 to 5 .
Thermal insulation material.

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