Phenol resin foam

Abstract

To provide a phenol resin foam which has small variations in strength in a width direction and a depth direction, and has uniform appearance of a cut surface in the width direction and the depth direction.SOLUTION: The density of a phenol resin foam is 20 kg / m3 or more and 100 kg / m3 or less, when the perpendicular width, depth and thickness of the phenol resin foam are represented by X, Y and Z, respectively, Z out of X, Y and Z is smallest, the difference in density of the phenol resin foam between the X direction and the Y direction is 0.1% or more and 6.0% or less, and the closed cell ratio of the phenol resin foam is 80% or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to phenolic foams. [Background technology]

[0002] In recent years, the demand for energy-saving performance has spread to a wide range of fields, including not only buildings but also automobiles, ships, industrial equipment, and home appliances. In particular, when thermal insulation performance is required, there are an increasing number of cases where thermal insulation materials, primarily intended for use as building insulation, are processed into the required shape and used as filling materials inside structures.

[0003] In particular, phenolic resin foam is preferred as an insulating material because of its excellent heat insulating properties, heat resistance, and fire resistance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5373622 Summary of the Invention [Problem to be solved by the invention]

[0005] Because phenolic resin foam is a thermosetting resin, it is extremely difficult to reshape it once it has been cured. Therefore, when using phenolic resin foam as a thermal insulation material, large-area phenolic resin foam manufactured for construction is used as the base, and the phenolic resin foam is processed according to the shape and dimensions to which the phenolic resin foam will be applied. When the dimensions to which the phenolic resin foam will be applied are small or the shape to which the phenolic resin foam will be applied is complex, large-area phenolic resin foam is processed to an appropriate size, or small pieces are combined to form multiple assemblies according to the dimensions and shape of the application area.

[0006] However, phenolic resin foam is required to have strength in addition to heat insulation properties. The inventors' investigations revealed that when small pieces of phenolic resin foam are assembled together to form an aggregate, there is variation in strength even for aggregates of the same shape and size formed from a single phenolic resin foam.

[0007] Furthermore, when the phenolic resin foam was cut in the width direction and the depth direction into small pieces, the cut surface would have periodic variations in color shade, which could result in a non-uniform appearance of the cut surface. If the cut surface of the small pieces had a non-uniform appearance, the aggregate of the small pieces would also have a non-uniform appearance, which could impair the appearance of the aggregate.

[0008] Further investigation by the inventors revealed that the variation in strength of the aggregate is due to variations in the strength in the width direction and the depth direction of the phenolic resin foam before it is processed into small pieces. If there is variation in the strength in the width direction and the depth direction of the phenolic resin foam before it is processed into small pieces, when the phenolic resin foam is processed into small pieces, the small pieces will also have variation in strength. Therefore, it is presumed that there will be variation in strength between an aggregate of small pieces in one range and an aggregate of small pieces in another range.

[0009] Therefore, an object of the present invention is to provide a phenolic resin foam having small variations in strength in the width and depth directions and having uniform appearances of cross sections in the width and depth directions. [Means for solving the problem]

[0010] In the present invention, we conducted extensive research to solve the above-mentioned problems and found that the above-mentioned problems can be solved by using a phenolic resin foam that has almost no difference in density between two perpendicular directions other than the thickness direction, regardless of the width or depth direction.

[0011] That is, the present invention provides the following [1] to [2]. [1] 1. A phenolic foam comprising: The density of the phenolic resin foam is 20 kg / m 3More than 100kg / m 3 is as follows: When the width, depth and thickness of the phenolic resin foam, which are orthogonal to each other, are designated as X, Y and Z, respectively, Z is the smallest of X, Y and Z, The density difference between the X direction and the Y direction of the phenolic resin foam is 0.1% or more and 6.0% or less, A phenolic resin foam, characterized in that the closed cell rate of the phenolic resin foam is 80% or more. [2] The phenolic resin foam according to [1], wherein the void ratio of the phenolic resin foam is 5% or less. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a phenolic resin foam having small variations in strength in the width and depth directions and having uniform appearances of cross sections in the width and depth directions. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a side view showing a schematic example of the positional relationship between the tip of the discharge nozzle and the lower surface material in the discharge step. [Figure 2] FIG. 2 is a graph showing the density distribution in the width direction of each small piece of Example 1 and Comparative Example 1. [Figure 3] FIG. 3 is a graph showing the density distribution in the depth direction of each small piece of Example 1 and Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described in detail below based on preferred embodiments thereof. However, the present invention is not limited to the following embodiments and can be practiced in various modifications within the scope of the present invention.

[0015] The accompanying drawings are drawn with priority given to understanding the present invention, and the dimensions and scale of each component are not necessarily accurate.

[0016] In the present invention, the width direction and depth direction of the phenolic resin foam are intended only to distinguish between two directions perpendicular to the thickness direction, which is the smallest dimension, and do not limit the width direction and depth direction in the use state or arrangement of the phenolic resin foam.

[0017] In the present invention, "cutting the phenolic resin foam in the width direction or X direction" refers to cutting the phenolic resin foam in the width direction or a direction parallel to the X direction, and the cut surface obtained by the cutting is an XZ plane. In the present invention, "cutting the phenolic resin foam in the depth direction or Y direction" refers to cutting the phenolic resin foam in the depth direction or a direction parallel to the Y direction, and the cut surface obtained by the cutting is a YZ plane.

[0018] In the present invention, the density of the phenolic resin foam, the density difference between the X direction and the Y direction, the closed cell rate and the void rate are determined by the methods described in the examples.

[0019] <Phenolic resin foam> The phenolic resin foam of this embodiment is The density of the phenolic resin foam is 20 kg / m 3 More than 100kg / m 3 is as follows: When the width, depth and thickness of the phenolic resin foam, which are perpendicular to each other, are defined as X, Y and Z, respectively, Z is the smallest of X, Y and Z, The density difference between the X direction and the Y direction of the phenolic resin foam is 0.1% or more and 6.0% or less, The phenolic resin foam has a closed cell rate of 80% or more.

[0020] The phenolic resin foam of this embodiment has the smallest thickness among the width, depth, and thickness.

[0021] The density difference between the X and Y directions of the phenolic resin foam of this embodiment is 6.0% or less, preferably 5.0% or less, more preferably 4.0% or less, and even more preferably 3.0% or less. If the density difference between the X and Y directions is 6.0% or less, the phenolic resin foam can be used as small pieces with uniform density. Furthermore, since the density of the small pieces of the phenolic resin foam is uniform, i.e., the density variation is small, the variation in strength such as compressive strength of the aggregate of the small pieces is also small, and the appearance of the cross section of the phenolic resin foam in the width and depth directions is also uniform.

[0022] The density of the phenolic resin foam of this embodiment is 20 kg / m 3 More than 100kg / m 3 or less, preferably 25 kg / m 3 More than 70kg / m 3 Less than or equal to 25 kg / m 3 More than 50kg / m 3 Density is 20 kg / m or less. 3 When the density is 100 kg / m or more, the decrease in mechanical strength such as compressive strength in the thickness direction is suppressed, the phenolic resin foam is less likely to break when handled, and surface brittleness is reduced. 3 If the density is below this, there is no risk of heat transfer to the resin portion increasing and the heat insulating performance decreasing. The density of the phenolic resin foam can be adjusted to a desired value mainly by changing the proportion of the foaming agent and the curing conditions.

[0023] The thickness of the phenolic resin foam of this embodiment is not particularly limited and can be set appropriately. The thickness of the phenolic resin foam is preferably 30 mm or more and 200 mm or less. A thickness of 30 mm or more can reduce the density difference in the X direction when using the manufacturing method described below. On the other hand, a thickness of 200 mm or less allows internal heat generated during the foaming and curing processes to be sufficiently released to the outside of the phenolic resin, making it easy to produce a product with a high closed cell content. The thickness is preferably 30 mm or more and 200 mm or less, more preferably 35 mm or more and 200 mm or less, and even more preferably 40 mm or more and 200 mm or less.

[0024] The phenolic resin foam of this embodiment has a closed cell ratio of 80% or more. A closed cell ratio of 80% or more suppresses replacement of the blowing agent in the phenolic resin foam with air, thereby suppressing a decrease in heat insulating performance. The closed cell ratio of the phenolic resin foam is preferably 85% or more, more preferably 90% or more.

[0025] The closed cell ratio of the phenolic resin foam can be adjusted to a desired value by, for example, changing the amount of foaming nucleating agent added, the temperature of the foamable phenolic resin composition when the face material and the foamable phenolic resin composition come into contact, the average temperature of the face material surface, and curing conditions.

[0026] The void fraction of the phenolic resin foam of this embodiment is preferably 5% or less. A void fraction of 5% or less provides a better appearance and also makes it easier to ensure compressive strength. In a preferred embodiment, the void fraction of the phenolic resin foam is 0.5% or more and 5.0% or less.

[0027] In the present invention, the void ratio is defined as follows: A cross section perpendicular to the XY plane of a phenolic resin foam is cut out, and the voids present in the cross section are measured by the method described below. 2 The above-mentioned spaces are considered to be voids, and the total area of ​​all voids on the cross section is divided by the area of ​​the cross section to obtain the void ratio.

[0028] Phenolic resin foams can be produced from known foamable phenolic resin compositions, which include, for example, a phenolic resin, a surfactant, a foaming agent, a foam nucleating agent, and an acidic curing agent, and may optionally contain other components.

[0029] As the foamable phenolic resin composition, for example, the foamable phenolic resin composition described in JP 2018-171885 A can be used.

[0030] <Surface material> The phenolic resin foam may have face materials on the upper and lower surfaces. Known face materials for phenolic resin foam can be used as the face materials. For example, the face materials described in JP 2018-171885 A can be used.

[0031] Phenolic resin foam can be used alone or bonded to an external component for a variety of applications. Examples of external components include board-shaped materials and sheets. Suitable board-shaped materials include wood-based boards such as ordinary plywood, structural plywood, particle board, and OSB, as well as cemented wood wool boards, cemented wood chip boards, gypsum boards, flexible boards, medium-density fiberboards, calcium silicate boards, magnesium silicate boards, and volcanic glass multi-layer boards. Suitable sheet-shaped materials include polyester nonwoven fabrics, polypropylene nonwoven fabrics, inorganic-filled glass fiber nonwoven fabrics, glass fiber nonwoven fabrics, paper, calcium carbonate paper, polyethylene-coated paper, polyethylene film, plastic moisture-proof films, asphalt waterproof paper, and aluminum foil (with or without holes).

[0032] <Method of manufacturing phenolic resin foam> Next, a method for producing the above-mentioned phenolic resin foam will be described.

[0033] A suitable method for manufacturing the phenolic resin foamed volume layer according to this embodiment is as follows: a preparation step of preparing a foamable phenolic resin composition; a mixing step of mixing the foamable phenolic resin composition in a mixer; a discharge step of discharging the mixed foamable phenolic resin composition onto a traveling lower surface material from a plurality of discharge nozzles arranged in the width direction; and a foam production process in which the foamable phenolic resin composition discharged onto the lower surface material is expanded until it adheres to the upper surface material to produce a phenolic resin foam.

[0034] A preferred feature of the method for producing a phenolic resin foam according to this embodiment is that, in the discharging step, a fixed distance is maintained between the tips of the multiple discharge nozzles and the traveling lower surface material, as described below. By maintaining a fixed distance between the tips of the discharge nozzles and the lower surface material, the discharged foamable phenolic resin composition does not fall straight onto the lower surface material in the depth direction (i.e., the direction in which the lower surface material travels). Instead, the foamable phenolic resin composition falls from the discharge nozzles in a spiral manner in the width and depth directions, causing the foamable phenolic resin compositions discharged from adjacent discharge nozzles to approach or intersect with each other. This allows the continuously discharged resin composition to be uniformly distributed on the lower surface material, regardless of the width direction (i.e., the X direction) or the depth direction (i.e., the Y direction), when viewed as a surface in the width and depth directions.

[0035] As a result, the obtained phenolic resin foam has an improved density difference between the X and Y directions while maintaining its performance. Even when the phenolic resin foam has an improved density difference between the X and Y directions, it is possible to form a high-quality phenolic resin foam aggregate in which the density variation among the small pieces is small and the strength variation among the aggregate of the small pieces is also small.

[0036] Furthermore, by improving the density difference between the X and Y directions, the uneven appearance of the small pieces, such as the periodic color shading on the cut surface (XZ plane) of the small pieces, was improved, and the appearance of the cut surface in the width and depth directions of the phenolic resin foam became uniform. From this, it is inferred that the color shading on the cut surface is also caused by the density difference between the width and depth directions of the phenolic resin foam.

[0037] One known method for leveling a foamable phenolic resin composition in the width direction is to supply the composition through multiple inlet ports in a die via multiple distributed flow paths, allow it to accumulate inside the die, and then discharge the composition in the form of a sheet from the die lip outlet onto a moving surface material (see Patent Document 1). In the method of Patent Document 1, the foamable phenolic resin composition is not discharged from the nozzle in a streaky fashion, but rather discharged in the form of a sheet that is uniformly leveled across the width. However, the discharge speed of the discharged sheet-shaped foamable phenolic resin composition and the moving speed of the lower surface material with which the sheet-shaped foamable phenolic resin composition comes into contact must be precisely adjusted, which is difficult to control. For example, in the method of Patent Document 1, if the moving speed of the lower surface material is faster than the discharge speed of the sheet-shaped foamable phenolic resin composition, the sheet-shaped foamable phenolic resin composition in contact with the lower surface material may tear in places, resulting in low-density areas in the depth direction of the molded phenolic resin foam, which may result in uneven density. On the other hand, if the movement speed of the lower surface material is slower than the discharge speed, some of the foamable phenolic resin composition will remain on the lower surface material and become wavy, which may result in high-density areas in the depth direction of the molded phenolic resin foam, resulting in an uneven density.

[0038] Returning to this embodiment, FIG. 1 is a side view schematically illustrating an example of the positional relationship between the tip of the discharge nozzle and the lower surface material during the discharge process of this embodiment. In the example of FIG. 1, the lower surface material 1 moves from right to left in the figure as indicated by the arrow. That is, the horizontal direction of the figure is the depth direction of the lower surface material 1, which is the Y direction of the target phenolic resin foam 2. The vertical direction of the figure is the thickness direction of the target phenolic resin foam 2, which is the Z direction. Note that, for simplicity of explanation, the distribution path and conveyor from the mixer to the discharge nozzle 3 are omitted in FIG. 1. Also, for simplicity of explanation, only one of the multiple discharge nozzles is shown. For ease of understanding, the target phenolic resin foam 2, which does not yet exist during the discharge process, is indicated by a dashed line.

[0039] If the vertical distance between the tip of the discharge nozzle 3 and the lower surface material 1 (the height from the lower surface material to the tip of the discharge nozzle) is H and the thickness of the desired phenolic resin foam 2 is T, then H = T + Δ, where the difference Δ is 0 mm to 100 mm, preferably 5 mm to 80 mm, more preferably 10 mm to 60 mm, and even more preferably 10 mm to 40 mm. If Δ is negative, i.e., if the tip of the discharge nozzle is positioned lower than the desired molded thickness, the discharged foamable phenolic resin composition will not fall in a coiled manner in the width and depth directions, and the foamable phenolic resin composition will not be sufficiently close to or intersect with each other in the width direction, resulting in poor density variation in the width direction. Furthermore, if Δ exceeds 100 mm, the amount of air entrapped in the discharged foamable phenolic resin composition will increase, resulting in an increased void fraction in the molded phenolic resin foam.

[0040] The number of discharge nozzles per meter of width of the target phenolic resin foam is, for example, 6 to 50, preferably 10 to 40, more preferably 15 to 35, and even more preferably 20 to 30. For example, when the inner diameter of the discharge nozzle is 6 to 18 mm, if the number of discharge nozzles per meter of width is less than 6, the spacing between adjacent nozzles in the width direction becomes too wide, resulting in insufficient proximity or intersection of the discharged foamable phenolic resin compositions, resulting in an inconsistent density. Furthermore, if the number of discharge nozzles per meter of width exceeds 50, the amount of air entrapped in the foamable phenolic resin composition increases, resulting in an increased void fraction. [Example]

[0041] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these.

[0042] (Preparation of Foamable Phenolic Resin Composition) A foamable phenolic resin composition was prepared in the same manner as in Example 1 of JP 2018-171885 A.

[0043] The mixer used was the one disclosed in Japanese Patent Laid-Open No. 10-225993. The distribution section of the mixer had 24 nozzles with an inner diameter of 10 mm at its tip, and was designed to distribute the mixed foamable phenolic resin composition uniformly.

[0044] The upper and lower surfaces are made of polyester nonwoven fabric (Asahi Kasei Fibers "Spunbond E05030", basis weight 30 g / m 2 , thickness 0.15 mm) was used.

[0045] The air comparison hydrometer used was a 1000 model manufactured by Tokyo Science Co., Ltd.

[0046] Example 1 The target molded thickness (T) of the phenolic resin foam was set to 50 mm, and the distance (H) between the tip of the discharge nozzle and the lower surface material was set to 60 mm, i.e., Δ = 10 mm. The foamable phenolic resin composition was then supplied to the mixing head of the mixer, discharged through a multi-port distribution pipe from the tip of the discharge nozzle at a flow rate of 30 kg / hr, and dropped onto the lower surface material moving at a constant speed. The distance between the two ends of the 24 discharge nozzles was set to 1000 mm. The width direction (i.e., the direction in which the discharge nozzles were aligned) and the depth direction of the upper surface material (i.e., the direction in which the lower surface material moved) were perpendicular to each other, and the width direction and depth direction corresponded to the width direction (i.e., X direction) and depth direction (i.e., Y direction) of the phenolic resin foam to be molded, respectively.

[0047] While the discharged foamable phenolic resin composition was being foamed, a top surface material was placed on the foamable phenolic resin composition, and the foamable phenolic resin composition sandwiched between the top and bottom surfaces was sent to a slat-type double conveyor in an atmosphere of 78°C. In the slat-type double conveyor, moderate pressure was applied from above and below through the surface materials to form the foam into a plate. The phenolic resin foam was then cured for a residence time of 15 minutes to a thickness of 50 mm. The phenolic resin foam was then cured for 3 hours in an oven at 110°C to obtain a phenolic resin foam.

[0048] The thickness, density, closed-cell ratio, density difference between the X and Y directions, void ratio, and appearance of the cut surface of the obtained phenolic resin foam were measured and observed by the following methods.

[0049] <Thickness of phenolic resin foam> Ten phenolic resin foams with a width of 50 mm and a depth of 50 mm, from which the upper and lower face materials were removed, were prepared. After marking the centers of the upper and lower XY planes of each phenolic resin foam, the thickness in the Z direction was measured with a caliper. The average value of the thicknesses of the ten samples was taken as the thickness T of the phenolic resin foam.

[0050] <Density of phenolic resin foam> A sample was prepared by removing the upper and lower face materials from a phenolic resin foam with a width of 20 cm and a depth of 20 cm. Then, in accordance with JIS K7222, the mass and apparent volume of the sample were measured to determine the density of the phenolic resin foam.

[0051] <Closed-cell ratio of phenolic resin foam> The closed-cell ratio of the phenolic resin foam was determined in the same manner as in the example of JP-A-2018-171885. The density of the phenolic resin was assumed to be 1.3 kg / L.

[0052] <Density difference between the X and Y directions> Two phenolic resin foams with a size of 200 mm in the X direction and 200 mm in the Y direction, excluding the 50-mm portions at both ends in the X direction of the obtained phenolic resin foam, were cut out adjacent to each other. After removing the upper and lower face materials, one was cut in the X direction and the other in the Y direction at intervals of 7 mm, respectively, to obtain 28 slices from one phenolic resin foam, for a total of 56 slices. The mass and apparent volume of each slice of the phenolic resin foam were measured to determine the density of each slice and the average density Da of all the slices. The measurement was carried out in accordance with JIS K7222, excluding the reference of the sample volume. Then, among the densities of all the slices, the highest density Dh and the lowest density Dl were determined, and the density difference Dd was determined from the following formula. The results are shown in Table 1. Dd = (Dh - Dl) × 100 / Da

[0053] <Void ratio of phenolic resin foam> Five phenolic resin foams measuring 100 mm wide and 100 mm deep were prepared. The void ratio was evaluated for each of the four sides (two XZ faces and two YZ faces) of each phenolic resin foam using the following method.

[0054] Make a color copy of each side and measure 2mm of the copy paper. 2 The above gaps were filled in with a black ballpoint pen. 2 If it was difficult to confirm the above voids, an enlarged copy was made as necessary and the magnification was adjusted accordingly. The copy was then scanned. The scanned image was analyzed using analysis software (WinRooF2015, manufactured by Mitani Shoji Co., Ltd.) to calculate the total area of ​​all voids on each surface divided by the total area of ​​each surface, which was used as the void ratio. The same procedure was performed on four surfaces of each of the five phenolic resin foams, for a total of 20 surfaces, and the average value was calculated.

[0055] <Appearance of the cut surface> The obtained phenolic resin foam was cut into pieces of 400 mm in the X direction and 400 mm in the Y direction, excluding both end 50 mm pieces in the X direction, and the appearance of the XZ surface and the YZ surface was visually observed under natural light.

[0056] (Examples 2 to 7 and Comparative Example 1) A phenolic resin foam was produced in the same manner as in Example 1, except that the thickness T, the distance H, or the number of discharge nozzles in the distribution section were changed as shown in Table 1.

[0057] Furthermore, from each of the 28 sections cut in the X direction and the 28 sections cut in the Y direction in Example 1 and Comparative Example 1, 14 sections (half of the 28) were extracted in order. Each of the 14 sections was numbered in order from 1 to 14. The density of all of the sections was measured. The density distribution in the X direction (width direction) was graphed and shown in Figure 2. The density distribution in the Y direction (depth direction) was graphed and shown in Figure 3.

[0058] (Comparative Example 2) A phenolic resin foam was obtained in the same manner as in Example 1, except that the distribution section of the mixer was replaced with a die having the same structure as the die disclosed in Example 1 of Japanese Patent No. 5373622.

[0059] Table 1 shows the production conditions, physical properties of the phenolic resin foams, and appearance of the cut surface in each of the examples and comparative examples.

[0060] [Table 1]

[0061] 2 and 3, it can be seen that the density of the slices of the phenolic resin foam is almost uniform in the depth direction, but the density varies more in the width direction than in the depth direction, in both Example 1 and Comparative Example 1. Therefore, it can be seen that the density difference between the X and Y directions can be considered to be the same as the density difference in the X direction.

[0062] 2 and 3, the phenolic resin foams of Examples 1 to 7 have small density differences between the X and Y directions, and therefore small variations in strength between the X and Y directions. According to the present invention, it is possible to provide a phenolic resin foam with small variations in strength between the width and depth directions and uniform appearances of cross sections in the width and depth directions. [Industrial Applicability]

[0063] According to the present invention, it is possible to provide a phenolic resin foam having small variations in strength in the width and depth directions and having uniform appearances of cross sections in the width and depth directions. [Explanation of symbols]

[0064] 1: Bottom material 2: Desired phenolic resin foam 3: Discharge nozzle

Claims

1. 1. A phenolic foam comprising: The density of the phenolic resin foam is 20 kg / m ３ More than 100kg / m ３ is as follows: When the width, depth and thickness of the phenolic resin foam, which are perpendicular to each other, are defined as X, Y and Z, respectively, Z is the smallest of X, Y and Z, The difference in density between the X direction and the Y direction of the phenolic resin foam is 0.1% or more and 6.0% or less, A phenolic resin foam characterized in that the closed cell rate of the phenolic resin foam is 80% or more.

2. The phenolic resin foam according to claim 1 , wherein the void fraction of the phenolic resin foam is 5% or less.

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