JP7573109B2 - Phenolic foam and method for producing same - Google Patents

Description

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

Insulation is an essential item used in buildings to prevent energy loss. With global warming emphasizing the importance of green growth in the world, insulation is becoming even more important to minimize energy loss.

Usually, it is easy to ensure thermal insulation by increasing the thickness of the insulation material, but once the thickness of the insulation material exceeds a certain level, the physical properties change depending on the position in the thickness direction, and the foam becomes easily damaged and warped, resulting in a deterioration in appearance and physical properties, and even a decrease in thermal conductivity.

As a result, in the past, in order to ensure the physical properties of thick products, there was a tendency to manufacture foams that exhibit uniform physical properties throughout the foam and have symmetrical physical properties based on the middle part (center) of the foam in the thickness direction.

However, in reality, it is not easy to achieve a symmetrical structure while reducing the deviation in physical properties throughout the thickness, and this is uneconomical in terms of cost and production efficiency.

The object of the present invention is to provide a thick phenolic foam that exhibits excellent physical properties more economically by adjusting the distribution of the closed cell ratio of the thick foam to increase production efficiency. Another object of the present invention is to provide a phenolic foam that prevents the foam from being damaged during the installation process, and that maintains excellent physical properties such as insulation and compressive strength at a constant level not only during the production of the foam but also during long-term use, and prevents the occurrence of deflection.

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

The object of the present invention is not limited to the object mentioned above, and other objects and advantages of the present invention not mentioned can be understood from the following description and can be more clearly understood from the examples of the present invention. It is also easy to understand that the object and advantages of the present invention can be realized by the means and combinations thereof shown in the claims.

The present invention provides a phenolic foam having a thickness of 90 mm or more, wherein when the foam is evenly divided into N slices (N≧7, where N is an odd number) from any surface of the foam in the thickness direction along the surface, the closed cell rate of a first surface layer portion (N ₁ ) is lower than the closed cell rate of a second surface layer portion (N _N ), and a slice (N _min ) having the smallest closed cell rate among the N slices is located between the first surface layer portion (N ₁ ) and an intermediate slice (N _c ).

The present invention also provides a method for producing a phenolic foam, which includes the steps of discharging a foaming composition containing a phenolic resin, a foaming agent, and a curing agent onto a facing material using a nozzle, and foaming and curing the discharged foaming composition, the nozzle having a discharge outlet with a length (L)/width (W) ratio of 1 or more and 2 or less.

The phenolic foam of the present invention is a thick foam that is more economical in preventing damage during the foam installation process, and exhibits excellent physical properties such as excellent insulation and compressive strength to a certain level not only during foam production but also during long-term use, and can prevent the occurrence of deflection.

The method for producing a phenolic foam according to the present invention can also improve production efficiency and provide a phenolic foam having the above physical properties more economically.

The above-mentioned effects and specific effects of the present invention will be described in the following description of the embodiment of the invention.

1 is a schematic diagram showing a phenolic foam according to an embodiment of the present invention being uniformly cut into N pieces (N=9) in the thickness direction. FIG. 1 is a schematic view of a nozzle outlet for discharging a foam composition according to an embodiment of the present invention. FIG. 13 is a schematic diagram showing a plurality of outlets arranged on a lower surface of a conveyor according to another embodiment of the present invention. FIG. 4 is a schematic diagram illustrating a method for measuring the degree of deflection of a phenolic foam according to another embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a method for measuring the dimensional stability of a phenolic foam according to another embodiment of the present invention.

The above-mentioned objects, features and advantages will be described in detail below with reference to the accompanying drawings, so that a person having ordinary skill in the art to which the present invention pertains can easily implement the technical idea of the present invention. In describing the present invention, if a detailed description of known technologies relating to the present invention is deemed to obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference symbols in the drawings are used to indicate the same or similar components.

Below, we will describe phenolic foams according to some embodiments of the present invention.

One embodiment of the present invention provides a phenolic foam having a thickness of 90 mm or more, wherein when the foam is evenly divided into N slices (N≧7, where N is an odd number) from any surface of the foam in the thickness direction along the surface, the closed cell rate of a first surface layer portion (N ₁ ) is lower than the closed cell rate of a second surface layer portion (N _N ), and the slice (N _min ) having the smallest closed cell rate among the N slices is located between the first surface layer portion (N ₁ ) and an intermediate slice (N _c ).

In general, the thicker the foam, the easier it is to ensure thermal insulation. However, when the foam exceeds a certain thickness, the curing reaction at the center of the foam in the thickness direction increases internal heat generation, and the heat is difficult to dissipate to the outside, causing the internal temperature of the foam composition to rise excessively. As a result, the physical properties of the foam may change significantly depending on the position in the thickness direction of the foam, such as bubbles near the center of the foam bursting, and the foam may be easily damaged and warped. When the foam warps, there is a high possibility of apparent defects and poor construction, and problems such as product shrinkage over a long period of time may occur. In addition, even if the thickness is increased, the thermal conductivity may decrease. For this reason, in the past, in order to ensure the physical properties of a thick product and prevent warping, there was a tendency to manufacture a foam whose physical properties are symmetrical with respect to the middle part in the thickness direction of the foam, by making the physical properties of the entire foam uniform. However, in reality, it is not easy to make a symmetrical structure while making the physical properties uniform throughout the thickness of a thick foam, and there is a problem that it is uneconomical in terms of cost and production efficiency.

In addition, although it is possible to separate the upper and lower surface layers of a foam during manufacturing, it is difficult to separate the upper and lower parts of the foam during construction. As a result, the impact on the weaker parts of the foam may vary greatly depending on which part of the upper or lower surface layer receives the impact. In particular, insulation materials, such as insulation materials for ceilings or floors, are arbitrarily positioned by workers during the installation process, stepped on, and cement is poured in and then allowed to mature for a certain period of time. Therefore, even if a foam shows excellent physical properties during manufacturing, the weaker parts of the foam may be significantly damaged during installation, causing a significant decrease in physical properties such as insulation and compressive strength during use, and deflection may occur, which may result in a decrease in thermal conductivity.

The phenolic foam has a thickness of about 90 mm or more, and has an asymmetric structure based on the middle part in the thickness direction of the foam, and by adjusting the position of the foam with the minimum closed cell ratio, the foam as a whole exhibits excellent physical properties such as thermal insulation and compressive strength, and is prevented from warping. Even if an impact is applied to either of the two surfaces of the phenolic foam during the installation process, the impact received by the weak parts of the foam can be reduced to the same or similar extent. As a result, the phenolic foam can exhibit excellent physical properties for a long period of time even after the construction process. The phenolic foam can have a thickness of about 110 mm or more, about 150 mm or more, or about 180 mm or more to 300 mm.

When the phenolic foam is evenly divided into N slices (N is an odd number greater than or equal to 7) from the surface of the foam in the thickness direction along the surface, the closed cell rate of a first surface layer portion (N ₁ ) is lower than the closed cell rate of a second surface layer portion (N _N ), and the slice (N _min ) having the smallest closed cell rate among the N slices is located between the first surface layer portion (N ₁ ) and an intermediate slice (N _c ).

In the present invention, in order to measure the distribution of the closed cell ratio according to the thickness of a foam, the foam is cut evenly into N pieces (N is an odd number of 7 or more) along the surface in the thickness direction from the surface. In this case, the thickness means the direction (Z direction) in which the foaming composition on the facing material grows, and the surface perpendicular to the thickness direction is the surface, which means the surface to which the facing material is attached during the production of the foam. If the foam has a facing material, the facing material is removed, and in order to accurately measure the closed cell ratio, both surfaces of the foam where the facing material was attached are cut by 5 mm each.

Then, from the surface of the foam, divide it into N (N is an odd number greater than or equal to 7) equal pieces in the thickness direction along the surface. Then, measure the closed cell ratio of each piece. N may be a constant number including an even number, but it is preferable for N to be an odd number in order to more clearly confirm whether the physical properties are symmetrical with respect to the center of the foam in the thickness direction. Each piece can have a thickness of about 10 mm to about 30 mm.

The phenolic foam includes a first surface and a second surface, the first surface layer portion includes the first surface, and the second surface layer portion means a slice including the second surface. Of the two slices at both ends including both surfaces of the foam, the slice with a low closed cell ratio is indicated as N ₁ (first surface layer portion), and the other slice is indicated as N _N (second surface layer portion), and the slices are indicated in order from N ₁ to N ₂ , N ₃ , N ₄ , N ₅ , ... and N _N. Among the slices, the slice located in the middle is indicated as the middle slice (N _c ). In other words, the middle slice (N _c ) means a slice located at 1/2 point in the thickness direction of the first surface layer portion (N ₁ ) and the second surface layer portion (N _N ). For example, Fig. 1 is a schematic diagram showing nine (N = 9) uniformly cut pieces of a phenolic foam according to an embodiment of the present invention in the thickness direction, in which the piece with the lowest closed cell content among the two pieces at both ends including both surfaces of the foam is _N1 (first surface layer), the other piece is _N9 (second surface layer), and the middle piece ( _Nc ) is _N5 . Also, the piece with the minimum closed cell content ( _Nmin ) is located at the fourth piece, i.e., _N4 .

The phenolic foam has an asymmetric structure in which the closed cell rate of the first surface layer portion (N ₁ ) is lower than that of the second surface layer portion (N _N ), and the piece (N _min ) having the smallest closed cell rate among the N pieces is located between the first surface layer portion (N ₁ ) and the middle piece (N _c ). As a result, even if an impact is applied to either the first surface layer portion or the second surface layer portion, the impact received by the piece (N _min ) having the smallest closed cell rate is similarly reduced, and the foam as a whole can be prevented from bending while maintaining excellent physical properties such as thermal insulation.

Usually, in the case of thick foams, attempts are made to improve the physical properties of the entire foam by making the physical properties have a symmetrical distribution in the thickness direction, but this is uneconomical as it is too costly and reduces production efficiency. Furthermore, the thicker the foam, the more practically impossible it becomes to make the physical properties have a symmetrical distribution.

Therefore, the phenolic foam has an asymmetric structure in which the closed cell rate of the first surface layer portion (N ₁ ) is lower than that of the second surface layer portion (N _N ), so that the foam can be produced more economically, and the piece (N _min ) having the minimum closed cell rate is located between the first surface layer portion (N ₁ ) and the middle piece (N _c ) having a lower closed cell rate than that of the second surface layer portion (N _N ), thereby achieving the desired effect. For example, in a foam in which the piece (N _min ) having the minimum closed cell rate is located between the middle piece (N _c ) and the second surface layer portion (N _N ) having a higher closed cell rate, there is no problem if an impact is applied to the first surface layer portion (N ₁ ). However, when an impact is applied to the second surface layer (N _N ), a large deflection occurs in the direction of the section (N _min ) having the minimum closed cell ratio, and the foam is significantly damaged, and the physical properties may be significantly reduced during use. The phenolic foam has the above structure, and thus can achieve the same or similar effects as a foam whose physical properties are completely symmetrical in the thickness direction of the foam, and is therefore economical.

The difference between the closed cell rate of the first surface layer portion (N ₁ ) and the closed cell rate of the second surface layer portion (N _N ) (=|closed cell rate of the second surface layer portion (N _N )−closed cell rate of the first surface layer portion (N ₁ )|) may be about 0.05% to about 5%. For example, it may be about 0.1% to about 5% or about 0.1% to about 3%. If the difference in the closed cell rate between the first surface layer portion (N ₁ ) and the second surface layer portion (N _N ) is less than the above range, the cost increases and the production efficiency decreases, making it uneconomical, whereas if it exceeds the above range, there is a limit to how well the foam as a whole can have excellent physical properties.

The closed cell ratio of the first surface layer portion (N ₁ ) and the closed cell ratio of the second surface layer portion (N _N ) may each be about 85% or more. For example, it may be about 85% to about 100%. By having the closed cell ratios in the above ranges, the first surface layer portion (N ₁ ) and the second surface layer portion (N _N ) can exhibit excellent initial thermal conductivity, prevent replacement of the foam with air, reduce the amount of change in thermal insulation performance over time, and exhibit excellent thermal insulation properties.

The phenol foam may have a maximum closed cell ratio in the second surface layer portion (N _N ), and a difference in closed cell ratio between the second surface layer portion (N _N ) and the piece (N _min ) having the minimum closed cell ratio (ΔC2=|closed cell ratio of second surface layer portion (N _N )-closed cell ratio of piece (N _min )|) may be about 1 to about 20%. For example, it may be about 1 to about 15% or about 1% to about 7%. In this case, if the difference in closed cell ratio between the piece (N _min ) having the minimum closed cell ratio and the second surface layer portion (N _N ) exceeds the above range, the replacement speed of the foaming agent in the bubbles with air increases, and not only the change in thermal conductivity over time increases, but also the mechanical strength that can withstand shrinkage stress in a high-temperature environment is damaged, and the dimensional change rate may be significantly deteriorated. As a result, the foam may easily and significantly warp. The difference in closed cell ratio between the first surface layer portion (N ₁ ) and the segment (N _min ) having the minimum closed cell ratio (ΔC1=|closed cell ratio of the first surface layer portion (N ₁ )−closed cell ratio of the segment (N _min )|) may be about 0.1 to about 20%. For example, it may be about 0.1 to about 10%.

The piece (N _min ) having the minimum closed cell ratio may have a closed cell ratio of about 70% or more. For example, it may be about 70% to about 89%. By adjusting the closed cell ratio of the piece (N _min ) in the above range, the phenolic foam can maintain low thermal conductivity for a long period of time, prevent warping, and improve dimensional stability. For example, if it is less than the above range, the replacement rate of the foaming agent in the cells with air increases, and the change in thermal conductivity over time may become large.

The phenolic foam may have a ratio of d1 to d2 with respect to a total thickness of the foam of about 0.2:0.8 to about 0.45:0.55. The d1 may be a ratio of a thickness from the first surface portion (N ₁ ) to a section (N _min ) having a minimum closed cell content with respect to a total thickness of the foam (d1=thickness from an upper surface of the first surface portion (N ₁ ) to a 1/2 point of the section (N _min ) having a minimum closed cell content/total thickness of the foam), and the d2 may be a ratio of a thickness from the second surface portion (N _N ) to a section (N _min ) having a minimum closed cell content with respect to a total thickness of the foam (d2=thickness from a lower surface of the second surface portion (N ₁ ) to a 1/2 point of the section (N _min ) having a minimum closed cell content/total thickness of the foam). In this case, the total thickness of the foam means the thickness of the foam after cutting both surfaces of the foam to which the facing material was attached by 5 mm each, and d1 and d2 mean the ratio of the vertical distance from the upper surface of the first surface layer or the lower surface of the second surface layer to a 1/2 point in the thickness direction of the slice having the minimum closed cell ratio (N _min ) as shown in FIG.

The piece (N _min ) having the minimum closed cell content is located at the point in relation to the first surface layer portion (N ₁ ) and the second surface layer portion (N _N ), and even if an impact is applied to either the first surface layer portion or the second surface layer portion, the impact received by the piece (N _{min ) having the minimum closed cell content is reduced to the same or similar extent, and the foam as a whole can be prevented from bending while having excellent physical properties such as thermal insulation. For example, if the piece (N min )} having the minimum closed cell content is out of the above range and located closer to the first surface layer portion (N ₁ ), the physical properties on the first surface layer portion (N ₁ ) side are significantly reduced, making it difficult to make the physical properties of the entire foam uniform to a certain degree or more, and shrinkage of the first surface layer portion (N ₁ ) including the facing material is apparently manifested, and the product is greatly bent in the direction of the first surface layer portion (N ₁ ), resulting in problems such as a reduction in compressive strength. Furthermore, if the piece having the minimum closed cell ratio (N _min ) is located closer to the second surface layer portion (N _N ), when an impact is applied to the second surface layer portion (N _N ), the impact received by the piece having the minimum closed cell ratio (N _min ) increases rapidly, making the piece more susceptible to damage and causing problems such as a large deflection of the product in the direction of the second surface layer portion (N _N ).

The phenolic foam may have a value (Y) obtained by dividing the difference (ΔC1, ΔC2) in the closed cell ratio between each of the surface layers (N ₁ , N _N ) and the section (N _min ) having the minimum closed cell ratio by the ratio (d1, d2) of the distance between each of the surface layers and the section having the minimum closed cell ratio, such that (|(ΔC2/d2)-(ΔC1/d1)|) is about 0.1 to about 9. For example, it may be about 0.1 to about 6.5 or about 0.1 to about 5. If the Y value exceeds the above range, there may be a problem that an impact received at a specific position in the thickness direction becomes large or the physical properties of the entire foam are deteriorated, causing deflection.

The phenol foam has the above-mentioned distribution of closed cell ratio, which allows the foam to exhibit excellent physical properties throughout and maintain excellent thermal conductivity even after long-term use.

Specifically, the phenolic foam may have a compressive strength according to KS M ISO 844 of about 100 kPa to about 200 kPa. For example, it may be about 115 kPa to about 200 kPa. Compressive strength refers to the pressure at which the foam breaks. By having a compressive strength in the above range, the phenolic foam can maintain an excellent balance between physical properties and exhibit excellent long-term durability even after distribution and construction.

The phenol foam may have a dimensional change rate of about 0% to about 2.0%. For example, the phenol foam may have a dimensional change rate of about 0% to about 1.0% or about 0% to about 0.7%. In this case, the dimensional change rate can be measured by the method described in Experimental Example 4.

As shown in FIG. 4, after 7 days at 25°C and 60% relative humidity, the foam may bend in a concave manner toward the floor (I) or in a convex manner toward the ceiling (II). In this case, the change in the corners (P1 to P4) in the case of (I) and the maximum separation distance (R1, R2) between the two longitudinal sides of the foam and the floor may affect the damage and overall deformation of the foam due to external impact. The phenol foam may have an average deflection of about 0 cm to about 1.5 cm in the case of (I) and/or (II), respectively. Alternatively, the phenol foam may have an average deflection of about 0.1 cm to about 0.7 cm or about 0.1 cm to about 0.5 cm, respectively.

The phenolic foam may have a thermal conductivity of about 0.017 W/m·K to about 0.020 W/m·K measured at an average temperature of 20°C according to KS L 9016.

The phenolic foam may have a thermal conductivity of about 0.018 W/m·K to about 0.022 W/m·K measured at an average temperature of 20°C after drying at 70°C for 7 days and then at 110°C for 14 days in accordance with EN13823.

The phenol foam contains the closed cell rate in the above-mentioned distribution, exhibits excellent physical properties such as compressive strength, prevents bending, and shows a change in thermal conductivity over time of about 10% or less.

Another embodiment of the present invention provides a method for producing a phenolic foam, comprising the steps of discharging a foaming composition containing a phenolic resin, a foaming agent, and a curing agent onto a facing material using a nozzle, and foaming and curing the discharged foaming composition, the nozzle having a discharge outlet with a length (L)/width (W) ratio of 1 to 2.

As described above, the above-mentioned manufacturing method can more economically manufacture a phenolic foam having a specific distribution of closed cell ratio and excellent physical properties throughout the foam. Furthermore, the phenolic foam manufactured according to the above-mentioned manufacturing method can reduce the impact received by the piece having the minimum closed cell ratio (N _min ) to the same or similar extent even when an impact is applied to either the first surface layer portion or the second surface layer portion, thereby preventing deflection throughout the foam as well as providing excellent physical properties such as thermal insulation and compressive strength. The above-mentioned items such as the thickness and closed cell ratio of the phenolic foam are as described above, except as otherwise specified below.

In the case of a phenolic foam having a normal thickness, when the foaming composition is continuously discharged onto the first face material using one nozzle and then molded into a plate between the conveyors in the curing oven, the foaming composition rapidly foams and cures to the set thickness, and the reaction heat generated during the reaction is easily radiated through the surface face material, so it is not difficult to have uniform physical properties throughout the thickness. On the other hand, in the case of a phenolic foam having a thickness of 90 mm or more, internal heat generation increases due to the curing reaction in the center of the foam in the thickness direction, and the heat is difficult to dissipate to the outside, so the internal temperature of the foaming composition rises excessively. As a result, the bubbles near the center of the foam are likely to burst. In addition, the foaming composition discharged onto the first face material (lower face material) expands in the direction of the second face material (upper face material) (Z direction), and when the product is thick, the time required for foaming and curing is relatively long. As a result, the foaming composition remains on the first face material (lower face material) for a longer period of time, and gradually accumulates on the first face material (lower face material), causing relatively excessive expansion, and the bubbles near the first face material (lower face material) tend to burst more easily. The thicker the foam, the more pronounced the variation in physical properties becomes, which can lead to a deterioration in the overall physical properties of the foam. To overcome this, a method has been proposed in which the foaming composition is discharged individually onto the upper and lower faces using nozzles, but this method requires complex equipment and increases costs.

The method for producing the phenolic foam according to another embodiment of the present invention includes a step of discharging a foaming composition including a phenolic resin, a foaming agent, and a curing agent onto a facing material 3 using a nozzle. At this time, the outlet 10, which is the inlet of the nozzle, may have a shape in which the length (L)/width (W) is 1 or more and 2 or less. For example, as shown in FIG. 2, it may have an elliptical shape in which the length (L) is longer than the width (W), and the length (L)/width (W) may be greater than 1 and less than 2. The outlet means an inlet through which the composition is discharged. In this case, in the ellipse, the length (L) means the length of the major axis, and the width (W) means the length of the minor axis. As shown in FIG. 3, the length (L) direction of the outlet may be parallel to the thickness direction (Z direction) of the foam, and the width (W) direction of the outlet may be parallel to the width direction (Y direction) of the foam.

The nozzle outlet may have a length (L)/width (W) (aspect ratio) of 1 or more and 2 or less. For example, the nozzle outlet may have an elliptical outlet having a length (L)/width (W) ratio of more than 1 and 2 or less. This prevents the hardened bubbles from collapsing due to the movement of the foaming composition, and prevents problems such as excessive foaming and expansion of the foaming composition near the surface material (e.g., the lower surface material) from which the foaming composition is discharged. For example, if the nozzle outlet has a rectangular structure rather than an ellipse, there may be problems such as the hardened material accumulating near the corners of the outlet. And, if the outlet has a circular or elliptical shape but the length (L)/width (W) is less than the above range, there may be problems such as excessive foaming and expansion occurring near the lower surface material from which the foaming composition is discharged, causing bubbles to easily break. If the length (L)/width (W) ratio exceeds the above range, the amount of the foaming composition spreading in the width direction of the foam (Y direction, the direction perpendicular to the direction of extrusion of the foaming composition) increases, and the bubbles that have hardened due to heating collapse due to the movement of the foaming composition, further slowing the foaming and expansion speed in the thickness direction of the foam (Z direction), which can cause problems such as an increase in the time and amount of the foaming composition remaining near the lower surface material and bubbles breaking.

The outlet can have a length (L) of about 10 mm to about 100 mm. If the length (L), which is the major axis of the outlet, is less than the above range, the pressure generated when the nozzle is discharged may increase, and if it exceeds the above range, there may be a problem that the pressure is low and proper foaming is not performed.

The foamable composition can be discharged at about 30 kg/min to about 100 kg/min.

The viscosity of the foaming composition at the time of ejection may be about 5,000 cps to about 40,000 cps at 25°C. By having a viscosity in the above range, the foaming composition can be ejected in a slurry form suitable for foaming and curing.

The temperature of the foaming composition during the ejection may be about 0°C to about 40°C. If the temperature range is less than the above range, the viscosity of the ejected material increases excessively, making it difficult to eject, and if the temperature range is exceeded, the foaming agent easily volatilizes, decreasing the thermal conductivity.

As shown in FIG. 3, the method for producing the phenolic foam may include a plurality of nozzles having the discharge ports 10 arranged along a direction (Y-axis direction, width direction of the foam) perpendicular to the flow direction of the foam composition (X-axis, i.e., the running direction of the facing material 3). Specifically, the number of the nozzles may be about 4 to about 12. The nozzles may be arranged in parallel at equal intervals.

The manufacturing method described above arranges the number of nozzles having the discharge outlets 10 in parallel at uniform intervals, and can induce uniform expansion not only in the direction in which the foaming composition grows (Z-axis direction, thickness direction of the foam), but also in the direction perpendicular to the flow direction of the foaming composition (X-axis, i.e., the running direction of the facing material) (Y-axis direction, width direction of the foam). This allows the growth and distribution of bubbles to be appropriately adjusted.

The foaming composition includes a phenolic resin, a foaming agent, and a curing agent. The phenolic resin can be obtained by reacting phenol and formaldehyde, and can include, for example, a resol-type phenolic resin (hereinafter, "resole resin"). The phenolic resin may be included in the phenolic foam in an amount of about 30% to about 90% by weight, about 50% to about 90% by weight, or about 55% to about 90% by weight. By including the phenolic resin in an amount within the above range, the phenolic foam can stably form small foam cells and realize excellent thermal conductivity.

The phenol foam may include a foaming agent. For example, the foaming agent may include one selected from the group consisting of hydrofluoroolefin (HFO)-based compounds, hydrocarbon-based compounds, and combinations thereof. Specifically, the hydrofluoroolefin-based compounds may include at least one selected from the group consisting of monochlorotrifluoropropene, trifluoropropene, tetrafluoropropene, pentafluoropropene, hexafluorobutene, and combinations thereof. The hydrocarbon-based compounds may include hydrocarbons having 1 to 8 carbon atoms. For example, the hydrocarbon-based compounds 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, hexane, heptane, cyclopentane, and combinations thereof. Alternatively, the hydrocarbon compound is a hydrocarbon having 1 to 5 carbon atoms, and includes 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, and combinations thereof, and is environmentally friendly and exhibits excellent heat insulation. The foaming agent may be included in an amount of about 6 to about 13 parts by weight based on about 100 parts by weight of the phenol foam.

The phenolic foam includes a hardener. The hardener may include an acidic hardener selected from the group consisting of toluenesulfonic acid, xylenesulfonic acid, benzenesulfonic acid, phenolsulfonic acid, ethylbenzenesulfonic acid, styrenesulfonic acid, naphthalenesulfonic acid, and combinations thereof.

The acidic hardener may be present in an amount of about 9 parts by weight to about 20 parts by weight per 100 parts by weight of the phenolic foam. The phenolic foam may exhibit appropriate crosslinking, hardening and foaming properties by containing the hardener in the above range.

The method for producing the phenolic foam includes a step of foaming and curing the discharged foam composition. The phenolic foam can be foamed and cured into a plate shape between conveyors in a curing oven. For example, the foaming and curing can be performed under temperature conditions of about 40°C to about 90°C. The foaming and curing can be performed for about 2 minutes to about 20 minutes, but is not limited thereto and can vary depending on the purpose and use of the invention.

Yet another embodiment of the present invention provides an insulating material containing the phenolic foam. The phenolic foam simultaneously exhibits excellent compressive strength, resistance to deflection, and excellent insulating properties, and can be used as an insulating material for buildings.

The building insulation material can further include a facing material on one or both sides of the phenolic foam, and the facing material can include aluminum to further improve flame retardancy.

(Example)
Example 1:
A foaming composition (25° C., 20,000 cps) containing 100 parts by weight of resol resin, 18 parts by weight of toluenesulfonic acid as a curing agent, 10 parts by weight of cyclopentane as a foaming agent, and a surfactant was prepared.

Six nozzles with elliptical outlets (length (L) = 10 mm) with a length (L) / width (W) ratio of 1.5 were arranged in parallel at equal intervals on the lower surface material along a direction (Y-axis direction, width direction of the foam) perpendicular to the movement direction of the conveyor 7 (X-axis, i.e., the running direction of the surface material).

The foaming composition was then discharged at 40 kg/min using the individual discharge ports onto a conveyor moving at a speed of 10 m/min, measuring 1200 mm wide and 190 mm thick, and having an ambient temperature of 70°C, where it was foamed and cured to produce a phenolic foam with a thickness of 190 mm.

Example 2:
A phenolic foam was produced in the same manner as in Example 1, except that a nozzle having a circular outlet (length (L) = 10 mm) with a length (L) / width (W) ratio of 1 was used.

Comparative Example 1:
A phenolic foam was produced in the same manner as in Example 1, except that a nozzle having an elliptical outlet (length (L) = 10 mm) with a length (L) / width (W) ratio of 2.5 was used.

Comparative Example 2:
A phenol foam was produced in the same manner as in Example 1, except that a nozzle having an elliptical outlet (length (L) = 10 mm) with a length (L) / width (W) ratio of 0.5 was used.

Evaluation Experimental Example 1: Closed cell ratio of each cut piece The face material attached to the phenol foam of each of the examples and comparative examples was removed, and both surfaces of the foam to which the face material had been attached were cut by 5 mm each.

Then, the foam was cut uniformly into nine pieces (N=9) from the surface in the thickness direction along the surface, and foam pieces of 2.5 cm (L) x 2.5 cm (W) x 2.0 cm (T) were produced so as to include the middle part throughout the entire thickness direction of the foam before cutting. At this time, of the two pieces at both ends including both surfaces of the foam, the piece with the lower closed cell ratio was designated _N1 (first surface layer part), and the other piece was designated _N9 (second surface layer part), and the individual pieces were designated _N2 , _N3 , _N4 , _N5 , _N6 , _N7 , _N8 , and _N9 in order from _N1 . As a result, the middle piece ( _Nc ) became _N5 .

The closed cell ratio of each of the specimens (N ₁ to N ₉ ) was measured using a closed cell ratio measuring device (Quantachrome, ULTRAPYC 1200e) according to the KS M ISO 4590 measurement method, and the results are shown in Table 1 below.

d1 is the ratio of the thickness (=N ₁ to N _min thickness) from the first surface layer portion (N ₁ ) to the slice (N _min ) having the minimum closed cell ratio to the total thickness of the foam (d1=N ₁ to N _min thickness/total foam thickness), and d2 is the ratio of the thickness (=N ₉ to N _min thickness) from the second surface layer portion (N ₉ ) to the slice (N _min ) having the minimum closed cell ratio to the total thickness of the foam (d2=N ₉ to N _min thickness/total foam thickness). In this case, the total thickness of the foam refers to the thickness of the foam after cutting off both surfaces of the foam to which the facing material was attached by 5 mm. The thicknesses N ₁ to N _min and N ₉ to N _min refer to the vertical distance from the upper surface of the first surface layer portion or the lower surface of the second surface layer portion to a 1/2 point in the thickness direction of the section (N _min ) having the minimum closed cell content, as shown in Fig. 1. That is, d1 refers to the thickness from the upper surface path of the first surface layer portion (N ₁ ) to a 1/2 point of the section (N _min ) having the minimum closed cell content / the total thickness of the foam, and d2 refers to the thickness from the lower surface path of the second surface layer portion (N ₁ ) to a 1/2 point of the section (N _min ) having the minimum closed cell content / the total thickness of the foam.

Experimental Example 2: Compressive Strength The phenolic foams of the examples and comparative examples were prepared into specimens of 150 mm (L) x 150 mm (W) x the same thickness as the foam including the facing, and the specimens were placed between the wide plates of a Lloyd Instrument LF Plus Universal Testing Machine. The UTM equipment was set to a speed of 10% mm/min of the specimen thickness, and a compressive strength experiment was started. The strength at the first compressive yield point during the thickness reduction was recorded. The compressive strength was measured according to the method of KS M ISO 844 standard, and the results are shown in Table 2 below.

Experimental Example 3: Deflection Figure 4 is a schematic diagram showing a simplified method for measuring the degree of deflection of a phenolic foam containing a facing material according to the present invention. The phenolic foam containing the facing material of the embodiment and the comparative example was placed on a flat floor so that the surface of the foam was in contact with the floor. The four corners (vertices) of the surface of the phenolic foam in contact with the floor and the distances (p1, p2, p3, p4) from the floor were measured. The maximum separation distances (r1, r2) between the two longitudinal sides of the phenolic foam and the floor were measured. At this time, when the foam is in close contact with the floor, each distance is "0".

The phenolic foam was then left for 7 days under conditions of 25°C and 60% relative humidity, after which the degree of deflection of the phenolic foam was measured. In cases where the foam surface was bent concavely toward the floor (I), the distances (P1, P2, P3, P4) between the four corners (vertices) and the floor were measured using the same method as above, and the degree of deflection of the phenolic foam was recorded in Table 2 using the following formula 1. In cases where the foam surface was bent convexly toward the ceiling (II), the maximum separation distances (R1, R2) between the two longitudinal sides of the phenolic foam and the floor were measured, and the degree of deflection of the phenolic foam was recorded in Table 2 using the following formula 2.

[Formula 1]
Degree of deflection (△S) = [|P1-p1| + |P2-p2| + |P3-p3| + |P4-p4|]/4

[Formula 2]
Degree of deflection (△S') = [|R1-r1| + |R2-r2|]/2

Experimental Example 4: Dimensional Stability FIG. 4 is a schematic diagram showing a simplified method for measuring the dimensional stability of the phenolic foam of the present invention.

The phenolic foams of the examples and comparative examples were prepared into test pieces measuring 100 mm (L) x 100 mm (W) x the thickness of the foam including the facing. Then, as shown in Figure 5, lines were drawn at n (n = 3) equal points in the length (L) and width (W) directions of the test piece, and the initial length (a) of each line was measured at 25°C.

The specimens were then left in an oven at 70°C for 48 hours, after which the length (a') at each point was measured, and the dimensional change rate (%) from the initial dimension was calculated using the following formula 3, and the average values are shown in Table 2. Dimensional stability was measured according to the method of KS M ISO 2796 standard.

[Formula 3]
Dimensional change rate (%) = (| initial length (a) - subsequent length (a') | / initial length (a)) x 100

In the above formula 3, the initial length (a) is the length of each of n equal lines in the length (L) and width (W) directions of the foam, and the subsequent length (a') means the subsequent length (a') of each line at each of the points after the foam is left in an oven at 70°C for 48 hours. Here, n may be 2 to 5.

Experimental Example 5: Initial thermal conductivity The phenolic resin foams of the examples and comparative examples were cut to 50 mm from either surface, and then cut into 300 mm x 300 mm pieces 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 Table 2 below.

Experimental Example 6: Long-term thermal conductivity The phenolic resin foams of the Examples and Comparative Examples were cut to 50 mm from either surface, and then cut into 300 mm x 300 mm pieces to prepare test pieces. The test pieces were dried at 70°C for 7 days and then at 110°C for 14 days in accordance with EN13823, and the thermal conductivity was measured at an average temperature of 20°C using a thermal conductivity instrument HC-074-300 (EKO Co., Ltd.). The results are shown in Table 2 below.

As shown in Table 1 above, the phenol foam of the embodiment exhibits excellent compressive strength, sufficient suppression of the degree of deflection, and excellent thermal conductivity. As described above, the present invention has been described with reference to the exemplary drawings, but the present invention is not limited to the embodiments and drawings disclosed in this specification, and it is clear that various modifications can be made by ordinary engineers within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration of the present invention have not been explicitly described and explained while describing the embodiments of the present invention, it goes without saying that the effects that can be predicted by the configuration should also be recognized.

d1: Thickness from the first surface layer (N ₁ ) to the section (N _min ) having the minimum closed cell rate relative to the total thickness of the foam d2: Thickness from the second surface layer (N _N ) to the section (N _min ) having the minimum closed cell rate relative to the total thickness of the foam 10: Nozzle outlet L: Length of outlet W: Width of outlet 3: Face material 7: Conveyor 100: Phenol foam

Claims (4)

A phenolic foam having a thickness of 90 mm to 300 mm ,
When the foam is evenly divided from any one surface into N (N≧7 odd number) slices having a thickness of 10 mm to 30 mm along the thickness direction from the surface, the closed cell ratio of a first surface layer portion (N ₁ ) is lower than the closed cell ratio of a second surface layer portion (N _N ), and a slice (N _min ) having the smallest closed cell ratio among the N slices is located between the first surface layer portion (N ₁ ) and an intermediate slice (N _c );
a difference between the closed cell rate of the first surface layer portion (N ₁ ) and the closed cell rate of the second surface layer portion (N _N ) is 0.1% to 3%;
the closed cell rate of the first surface layer portion (N ₁ ) and the closed cell rate of the second surface layer portion (N _N ) are each 85% or more;
The closed cell ratio of the piece (N _min ) having the minimum closed cell ratio is 70% or more;
The second surface layer portion (N _N ) has a maximum closed cell ratio;
a difference in closed cell ratio between the second surface layer portion (N _N ) and the piece (N _min ) having the minimum closed cell ratio is 1% to 7%;
Phenolic foam. The ratio of d1 to d2 with respect to the total thickness of the foam is 0.2:0.8 to 0.45:0.55;
The d1 is a ratio of the thickness from the first surface layer portion (N ₁ ) to the section (N _min ) having the minimum closed cell ratio to the entire thickness of the foam, and the d2 is a ratio of the thickness from the second surface layer portion (N _N ) to the section (N _min ) having the minimum closed cell ratio to the entire thickness of the foam.
2. The phenolic foam of claim 1. The deflection of the foam after 7 days under conditions of 25°C and 60% relative humidity is 0.1 cm to 0.7 cm.
The phenolic foam of claim 1 or 2. A thermal conductivity of 0.018 W/m·K to 0.022 W/m·K measured at an average temperature of 20°C after drying at 70°C for 7 days and then at 110°C for 14 days in accordance with EN 13823;
The phenolic foam of claim 1 or 2.

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