Foamed Resin Insulation Materials and Their Preparation Method

Abstract

This invention provides a foamed resin insulation material and its manufacturing method, which can reduce the difference in linear expansion coefficients between the metal and the foamed resin insulation material, thereby significantly reducing the thermal stress generated in the foamed resin insulation material and preventing cracking. The material is composed of a foamed resin molded body, which is formed by foaming an unfoamed resin material mixed with a negative thermal expansion material that shrinks with heating and expands with cooling. A fiber sheet composed of interlaced warp and weft yarns is integrated with the inner and outer surfaces of the foamed resin molded body.

Description

Technical Field

[0001] This invention relates to foamed resin insulation materials and their preparation methods. Background Technology

[0002] In the past, when using foamed resin insulation materials to insulate fluid piping and fluid storage containers, especially in the case of keeping low-temperature fluids cold, foamed resin insulation materials with independent air bubbles, such as foamed rigid polyurethane resin, are usually molded into a shape that surrounds the piping and fluid storage containers.

[0003] However, when fluid flows and the temperature changes, not only the piping and storage containers, but also the insulation material in contact with the piping and storage containers will expand or contract due to the temperature changes of the fluid.

[0004] Moreover, piping and storage containers are usually made of metal, while foamed resin insulation materials have a larger coefficient of linear expansion compared to metal.

[0005] Furthermore, if the fluid flowing in the piping or stored in the storage container is a cryogenic fluid, for example, if the cryogenic fluid is liquid nitrogen (LN2) at -196°C or liquid hydrogen (LH2) at -253°C, if air enters the gap between the interface between the piping or storage container and the foamed resin insulation material, the oxygen in the air (liquefaction temperature -183°C) may liquefy and accumulate as liquid oxygen. The accumulated liquid oxygen may lead to an explosion or fire based on the ignition of combustibles (see, for example, Patent Document 1).

[0006] Therefore, it is considered to use an adhesive to bond the two together so as not to create a gap between the piping or storage container and the foamed resin insulation material.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2016-176511 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] However, the linear expansion coefficient of SUS316L, a metal commonly used in piping and storage containers, is α = 10~16 ppm / K (where ppm = 1 × 10⁻⁶). -6In contrast, the linear expansion coefficient of polyurethane foam resin is α = 50-60 ppm / K. If the aforementioned cryogenic fluid flows through it, due to the significant difference in the linear expansion coefficients between the metal and the foam resin insulation material, thermal stress will act on the insulation material, easily causing cracks. Air may enter through these cracks. Furthermore, if the cryogenic fluid is liquid hydrogen, the above problems will be further aggravated because liquid hydrogen has a liquefaction temperature of -253°C.

[0012] Therefore, the purpose of this invention is to eliminate the above-mentioned problems, reduce the difference in the coefficient of linear expansion between the metal and the foamed resin insulation material, thereby greatly reducing the thermal stress generated in the foamed resin insulation material and preventing cracks.

[0013] Methods for solving problems

[0014] The first feature of the present invention is that it is composed of a foamed resin molded body, which is formed by foaming an unfoamed resin material mixed with a negative thermal expansion material that shrinks with heating and expands with cooling.

[0015] According to the first feature of the present invention, a negative thermal expansion material is mixed into the foamed resin molded body. Therefore, the negative thermal expansion material shrinks as the temperature rises and expands as the temperature decreases. The negative thermal expansion material undergoes expansion and contraction changes based on the temperature change of the fluid. As a whole, the expansion and contraction changes of the foamed resin insulation material are suppressed, and the difference between the linear expansion coefficients of the metal and the foamed resin molded body can be reduced.

[0016] Therefore, it can prevent cracks in foamed resin insulation materials that are associated with the shrinkage of piping and storage containers that carry extremely low temperature fluids.

[0017] The second feature of the present invention is that the fiber sheet composed of intersecting warp and weft yarns is integrated with the inner and outer surfaces of the foamed resin molded body.

[0018] According to the second feature of the present invention, in addition to achieving the above-mentioned effects of the first feature of the present invention, the resistance brought by the fiber sheet can further suppress the expansion and contraction of the foamed resin molded body based on temperature changes, and can further reduce the difference in the coefficient of linear expansion between the metal and the foamed resin molded body.

[0019] The third feature of the present invention is that the foamed resin molded body is integrated with the fiber sheet composed of intersecting warp and weft yarns in a layered state.

[0020] According to the third feature of the present invention, the fiber sheet composed of intersecting warp and weft yarns is integrated with each other in a layered state, thereby increasing the reinforcement generated by the fiber in the two-dimensional direction and further reducing the difference in the coefficient of linear expansion between the metal and the foamed resin molded body.

[0021] The fourth feature of the present invention is that the multilayer fiber sheets are integrated with the foamed resin molded body.

[0022] According to the fourth feature of the present invention, the effect of suppressing stretching associated with temperature changes can also be enhanced in the thickness direction by using multilayer fiber sheets.

[0023] The fifth feature of the present invention is that cellulose nanofiber powder is incorporated into the above-mentioned foamed resin molded body and integrated into it.

[0024] According to the fifth feature of the present invention, by incorporating cellulose nanofiber powder into the foamed resin molded body for integration, the coefficient of linear expansion of the foamed resin molded body is further reduced, making it easier to approach the coefficient of linear expansion of metal.

[0025] The sixth feature of the present invention is that the aforementioned negative thermal expansion material is selected from zirconium tungstate phosphate (Zr2WO4(PO4)2) and zirconium sulfate phosphate (Zr2SP2O). 12 The above-mentioned non-foamed resin material is selected from one of the following: BiNi1-xFexO3, zirconium tungstate (ZrW2O8), and silicon oxide (Li2O-Al2O3-nSiO2), which are perovskite-structured oxide ceramics composed of bismuth-nickel-iron; the above-mentioned non-foamed resin material is selected from one of non-foamed polyurethane resin, non-foamed polystyrene resin, non-foamed polyethylene resin, non-foamed polyester resin, and non-foamed phenolic resin; and the above-mentioned fiber sheet is selected from glass fiber, carbon fiber, and aramid fiber.

[0026] The seventh feature of the present invention is that the negative thermal expansion material is zirconium tungstate phosphate (Zr2WO4(PO4)2), the unfoamed resin material is unfoamed polyurethane resin, the fiber sheet is a cloth made of glass fiber, and cellulose nanofiber powder is mixed into the foamed resin molded body to form an integral body, wherein the negative thermal expansion material is mixed in at least 0.75 vol% relative to the volume of the foamed resin molded body.

[0027] The eighth feature of the present invention is that the negative thermal expansion material is zirconium tungstate phosphate (Zr2WO4(PO4)2), the unfoamed resin material is unfoamed polyurethane resin, the fiber sheet is a cloth made of glass fiber, and in the foamed resin molded body, more than 3 wt% of cellulose nanofiber powder is mixed in relative to the amount of unfoamed resin filled and integrated.

[0028] The ninth feature of the present invention is that the negative thermal expansion material is zirconium tungstate phosphate (Zr2WO4(PO4)2), the unfoamed resin material is unfoamed polyurethane resin, the fiber sheet is a cloth made of glass fiber, and in the foamed resin molded body, more than 1 wt% of cellulose nanofiber powder is mixed in relative to the amount of unfoamed resin filled and integrated, and further, multiple layers of fiber sheets made of intersecting warp and weft yarns are integrated together, and more than 0.75 vol% of the negative thermal expansion material is mixed in relative to the volume of the foamed resin molded body.

[0029] According to the ninth feature of the present invention, the multilayer fiber sheet and the foamed resin molded body are integrated, thereby making the coefficient of linear expansion close to that of metal even with a small amount of cellulose nanofibers and negative thermal expansion material mixed in.

[0030] The tenth manufacturing method of the present invention is characterized in that a negative thermal expansion material composed of zirconium tungstate phosphate (Zr2WO4(PO4)2) is mixed into an unfoamed polyurethane resin, and the unfoamed resin material in this state is filled into a mold in such a way as to be laminated with a fiber sheet of glass cloth composed of intersecting warp and weft yarns, and foamed and cured in the mold to form a shape. Attached Figure Description

[0031] Figure 1 This is a cross-sectional view of the fluid transport piping.

[0032] Figure 2 This is a graph showing the change in the coefficient of linear expansion caused by variations in the amount of negative thermal expansion material added.

[0033] Figure 3 This is a longitudinal section view of the foamed resin insulation material.

[0034] Figure 4 It is a graph showing the change in the coefficient of linear expansion.

[0035] Figure 5 It is a graph showing the change in the coefficient of linear expansion.

[0036] Figure 6 It is a graph showing the changes in the coefficients of linear expansion.

[0037] Figure 7 It is a graph showing the changes in the coefficients of linear expansion.

[0038] Figure 8 It is a graph showing the changes in the coefficients of linear expansion.

[0039] Figure 9 It is a graph showing the changes in the coefficients of linear expansion.

[0040] Figure 10 This is a three-dimensional schematic diagram of the test specimen using foamed resin insulation material a in the liquid nitrogen immersion test.

[0041] Figure 11 This is a three-dimensional schematic diagram of the test specimen using foamed resin insulation material b in the liquid nitrogen immersion test.

[0042] Figure 12 In the diagram, (a) is a longitudinal section side view of the 2B piping cooling verification model using liquid nitrogen, (b) is the longitudinal section view of AA in (a), and (c) is the longitudinal section view of BB in (a).

[0043] Figure 13 yes Figure 12 A magnified view of a portion of (a).

[0044] Figure 14 It is a table showing the values ​​of various physical properties.

[0045] Figure 15 This is a table showing the results of FEM stress analysis.

[0046] Figure 16 This is a temperature distribution table showing the results of the verification test.

[0047] Figure 17 In the table, (a) is a table showing the temperature changes of foamed resin insulation material a, and (b) is a table showing the temperature changes of foamed resin insulation material b.

[0048] Figure 18 In the figure, (a) is the curve of strain variation of foamed resin insulation material a, and (b) is the curve of strain variation of foamed resin insulation material b.

[0049] Figure 19 This is a table showing the thermal stress calculated from the strain.

[0050] Figure 20 In the diagram, (a) is a longitudinal section view of the 2B piping cooling verification model using liquid helium, and (b) is a longitudinal section view of the CC line in (a).

[0051] Figure 21 It is a table showing the values ​​of various physical properties.

[0052] Figure 22 This is a table showing the results of FEM stress analysis.

[0053] Figure 23 This is a table showing the temperature distribution representing the results of the verification test.

[0054] Figure 24 The graphs show the temperature changes: (a) is the temperature change graph for the first cooling cycle, and (b) is the temperature change graph for the second cooling cycle.

[0055] Figure 25 It is a graph showing the change in strain during the cooling test.

[0056] Figure 26 It is a table showing the stress calculated from the strain.

[0057] Figure 27 This is a magnified view of a portion of the foamed resin molded body.

[0058] Figure 28 This is a graph showing the variation of the coefficient of linear expansion in accordance with the experimental results.

[0059] Figure 29 In the diagram, (A) is an exploded perspective view illustrating the concept of an integrated adhesive method, and (B) is an exploded perspective view illustrating the concept of a multi-layer injection integrated method.

[0060] Figure 30 This is a perspective view of a longitudinal section of a foamed resin molded body according to another embodiment. Detailed Implementation

[0061] The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0062] For metal fluid transport piping and fluid storage containers connected to the piping, their entire circumference is insulated or cooled by surrounding them with foamed resin insulation material, such as... Figure 1 The diagram shows a cross-sectional view of a piping system as an example.

[0063] As the metal used to form the aforementioned piping and storage containers, SUS316L is often used, for example, in the transportation of cryogenic fluids such as liquefied natural gas (LNG) and liquid nitrogen (LN2). The linear expansion coefficient α of this metal is 10–16 ppm / K (where ppm = 1 × 10⁻⁶). -6 ).

[0064] Furthermore, the aforementioned foamed resin insulation material is formed by layering cold insulation material a, cold insulation material b, and cold insulation material c. In particular, the cold insulation material a, which is connected to the metal pipe P, is mixed with unfoamed polyurethane resin (the linear expansion coefficient α of the foamed resin molded body is 50 to 60 ppm / K) which is usually used as a low-temperature foamed resin insulation material. It contains white powder composed of crystals of zirconium tungstate phosphate (Zr2(WO4)(PO4)2), which is a negative thermal expansion material (manufactured by Nippon Chemical Industry Co., Ltd. (trade name "cerafit")), and is foamed in this state to form a shape along the outer surface of the pipe P and the storage container.

[0065] In order to make the above-mentioned polyurethane resin foam, foaming agents such as carbon dioxide (water formulation-PUF), HFC-PUF, and HFO-PUF are used. However, in this application, carbon dioxide is used to foam the cold insulation material a, which is formed by polyurethane foam. As a foaming agent, a water-based polyol reacts with isocyanate to generate carbon dioxide, and then foaming and molding are performed.

[0066] It should be noted that insulation material b and insulation material c can be any one of water-based PUF, HFC-PUF, or HFO-PUF.

[0067] In addition, depending on the state of foaming, the lower the density of the molded product, the lower the thermal conductivity. However, in extremely small conditions, the bubble film becomes thinner or there are more continuous bubbles, thus increasing radiative heat transfer and convection, which in turn increases the thermal conductivity.

[0068] Generally speaking, the density is 50 kg / m³. 3 At this point, the thermal conductivity is at its minimum.

[0069] The linear expansion coefficient of the zirconium tungstate crystal is -3ppm / K. The metal-oxygen atom bonds are strong, so it is not easy for the volume of each unit to expand due to heating. The bond angles between the units deform in the direction that reduces the volume of the space within the structure. Thus, as a whole, the crystal is a material that thermally shrinks approximately linearly with increasing temperature over a wide temperature range.

[0070] It should be noted that the white powder (manufactured by Nippon Chemical Industries, Ltd. (trade name "Cerafit")) composed of zirconium tungstate phosphate (Zr2(WO4)(PO4)2), which is the aforementioned negative thermal expansion material, has a specific surface area of ​​0.2 m². 2 / g, D50 = 18.7μm, bulk density 1300kg / m³ 3 The temperature range of -100 to 800℃ shows a linear expansion coefficient α = -3ppm / K.

[0071] [Experimental Example 1]

[0072] Next, as Figure 2 The curves show the changes in the coefficient of linear expansion caused by the change in the amount of negative thermal expansion material added relative to the above-mentioned foamed polyurethane resin molded body.

[0073] It should be noted that B in the figure represents each measurement point.

[0074] According to the measurement results, the coefficient of linear expansion of SUS316L, a metal material used in piping, storage containers, etc., is 16 ppm / K (line M in the figure). In contrast, it is 51.4 ppm / K without the addition of a negative thermal expansion material. According to the curve, it can be predicted that if the amount of negative thermal expansion material added is increased, the coefficient of linear expansion of the foamed molded body will decrease linearly. If the coefficient of linear expansion is 14 to 15 vol% relative to the volume of the foamed resin molded body, it will be close to the coefficient of linear expansion of the aforementioned metal material (line M in the figure).

[0075] It should be noted that the amount of negative thermal expansion material added is calculated based on the bulk density of the negative thermal expansion material.

[0076] [Experimental Example 2]

[0077] Next, as Figure 3 The longitudinal section of the foamed resin insulation material is shown. The foamed resin insulation material is manufactured by foaming a layer of glass cloth GC, composed of interlaced warp and weft yarns, into the outer surface (surface and back) of the polyurethane foam (PUF). The changes in the coefficient of linear expansion based on the amount of negative thermal expansion material added are investigated for this glass cloth-integrated foamed resin insulation material (cold insulation material) a and a foamed resin insulation material (cold insulation material) without glass cloth b. Figure 4 The curve graph.

[0078] Thus, by integrating a single layer of glass cloth GC, the overall amount of negative thermal expansion material is reduced by approximately 36% even without the addition of negative thermal expansion material (at each measurement point B). When the amount of negative thermal expansion material added is 10 vol% relative to the volume of the foamed resin molded body (at each measurement point A), it is further reduced by approximately 26%.

[0079] [Experiment Example 3]

[0080] Next, as Figure 5 As shown, the effect of the number of laminated glass cloth GC was investigated, and the change line G (the approximate line of each measurement point G) was obtained.

[0081] Therefore, it can be seen that by simultaneously laminating two sheets of glass cloth GC on the surface of the foamed resin insulation material, even without adding a negative thermal expansion material, the coefficient of linear expansion is quite close to that of SUS316L metal (the M line in the curve), for example, it is comparable to that of aluminum (coefficient of linear expansion α = 24 ppm / K). Figure 5 The concentration of Al in the sample decreased by 20.5 ppm / K compared to the previous value.

[0082] [Experiment Example 4]

[0083] The change in the coefficient of linear expansion α based on the variation in the amount of negative thermal expansion material added was investigated when the glass cloth GC integrated with polyurethane foam (PUF) was in one-layer and two-layer configurations. The variation lines G1 (variation lines at each measurement point G1) for one-layer configuration and G2 (variation lines at each measurement point G2) for two-layer configurations are shown in the figure. Figure 6 .

[0084] According to curve G2, when the amount of negative thermal expansion material added is 0.75 to 1 vol% relative to the volume of the foamed resin molded body, the coefficient of linear expansion α decreases sharply.

[0085] It should be noted that in the figure, M is the coefficient of linear expansion of SUS316L, and Al is the coefficient of linear expansion of aluminum.

[0086] [Experiment Example 5]

[0087] Next, a curve was plotted showing the change in the coefficient of linear expansion α resulting from the addition of cellulose nanofibers (CNF) to polyurethane foam (PUF), as shown below. Figure 7 .

[0088] Figure 7 In the figure, the first variation line G0 when the amount of cellulose nanofibers (CNF) added is changed relative to the foamed polyurethane resin without glass cloth GC, the second variation line G1 when the amount of cellulose nanofibers (CNF) added is changed relative to the glass cloth GC with one integrated foamed polyurethane resin, and the third variation line G2 when the amount of cellulose nanofibers (CNF) added is changed relative to the glass cloth GC with two integrated foamed polyurethane resins are plotted.

[0089] In the figure, for comparison, the line Al representing the linear expansion coefficient of aluminum is shown, and the linear expansion coefficient α of metal SUS316L is shown as 16ppm / K (the line M in the figure).

[0090] Therefore, it can be seen that by adding 3 wt% cellulose nanofibers (CNF) to the glass cloth GC with a two-layer integrated polyurethane resin content, the coefficient of linear expansion is close to that of metal SUS316L.

[0091] It should be noted that the cellulose nanofibers (CNF) are manufactured under the trade name (S-CNF (water-soluble)) by Yokogawa Bio Frontier. They are typically 1 / 5 the strength of iron, exhibit 5 times the strength of iron, and show a coefficient of linear expansion α = 0.1–0.2 ppm / K (0–100°C).

[0092] [Experiment Example 6]

[0093] Regarding the curve showing the change in the coefficient of linear expansion α when polyurethane foam is used to integrally form glass cloth GC as a single layer and the amount of cellulose nanofibers (CNF) added therein is varied, Figure 8 The paper discloses the variation lines C0, C1, and C2 when the amount of negative thermal expansion material added is 0 vol%.

[0094] [Experiment Example 7]

[0095] Regarding the curve showing the change in the coefficient of linear expansion α of polyurethane foamed glass cloth GC as a two-layer integral structure, and the variation in the amount of cellulose nanofibers (CNF) added therein, in Figure 9 The following curves are disclosed: D0 when the amount of negative thermal expansion material added is 0 vol%, D1 when the amount of negative thermal expansion material added is 0.25 vol%, D2 when the amount of negative thermal expansion material added is 0.5 vol%, D3 when the amount of negative thermal expansion material added is 0.75 vol%, D4 when the amount of negative thermal expansion material added is 1 vol%, D5 when the amount of negative thermal expansion material added is 2 vol%, and D6 when the amount of negative thermal expansion material added is 4 vol%.

[0096] Therefore, by integrating the multilayer fiber sheet with the resin, adding more than 1 wt% of cellulose nanofibers (CNF), and mixing in more than 0.75 vol% of negative thermal expansion material, it is possible to approach the linear expansion coefficient α = 16 ppm / K of metal SUS316L (on the line M in the figure).

[0097] [Experimental Example 8] Liquid nitrogen (LN2) immersion test

[0098] like Figure 10 As shown, a 200×25×25mm foamed resin insulation material is fabricated by foaming two layers of glass cloth GC composed of interlaced warp and weft yarns with the outer surface (surface and back) of foamed polyurethane resin (PUF). This is in contrast to two-layer glass cloth integrated foamed resin insulation materials a and a, which incorporate 1 vol% of a negative thermal expansion material. Figure 11 The foamed resin insulation material b without the addition of negative thermal expansion material and without glass cloth GC is shown. Foamed resin insulation material a or foamed resin insulation material b is bonded to one side of a 200×25×25mm SUS316 L prism M using a polyurethane adhesive and then cured. The resulting material is used as the test specimen.

[0099] It should be noted that in the foamed resin insulation material a, the glass cloth surface is bonded to the SUS316L prism M. These test specimens were subjected to a 5-day cyclic test: completely immersed in liquid nitrogen (-196℃) for 8 hours, and then placed at room temperature to confirm whether cracks occurred in the foamed resin insulation material (PUF) at the bonding interface and near the interface due to the difference in the coefficient of linear expansion between the foamed resin insulation material and SUS316L.

[0100] The results of the cyclic test of liquid nitrogen (LN2) impregnation showed that peeling E occurred at the adhesive interface of the foamed resin insulation material b, starting from the apex of the adhesive surface. Figure 11 No peeling or cracking of the polyurethane foam (PUF) was found at the bonding interface of the foamed resin insulation material a.

[0101] In the FEM stress analysis using SolidWorks Simulation manufactured by Dassault Systemes SolidWorks Corporation, the principal stresses generate the maximum stress at the four vertices of the bond surface. However, the safety factor of this part of the foamed resin insulation material b is 0.4 times, resulting in cracks. In the foamed resin insulation material a, the safety factor is 1.2 times, resulting in no cracks. This is consistent with the results of this immersion in liquid nitrogen (-196℃).

[0102] [Experimental Example 9] Cooling test of 2B piping (SUS316L) using liquid nitrogen (LN2) at -196°C

[0103] (2B piping cooling verification model fabrication)

[0104] like Figure 12 (a), (b), (c) Figure 13 As shown, the piping is SUS316L based on JIS standard 2B (A is nominally 50A, outer diameter 60.5mm) × 4,000mm.

[0105] The insulation structure is designed as a three-layer structure. The insulation thickness is calculated based on the following conditions: the outer surface of the insulation material does not condense under the environmental conditions of an external air temperature of 30°C and a relative humidity of 85%, and the interface temperature between the first and second layers of the insulation material is above the liquefied natural gas (LNG) temperature (-163°C). The insulation thickness is 10mm for the first layer, 40mm for the second layer, and 60mm for the third layer.

[0106] To impart moisture-proof / waterproof properties to the tube cover, an aluminum kraft paper sheet with two layers of glass cloth (Unitika Co., Ltd. product, model: L55MN104F, cloth type: gauze weave, 2.5mm mesh) is placed on the inner surface of the concave steel mold used for tube cover manufacturing. In addition, two layers of glass cloth are placed on the convex part of the steel mold. A water-based polyurethane resin with a negative thermal expansion material added at 1 vol% of the injection volume is injected, foamed, and molded to be integrated with the glass cloth. The resulting material is used as the first layer of the cold insulation material, a foamed resin insulation material.

[0107] As a comparison, a material with an outer surface of aluminum kraft paper, no glass cloth on the inner surface, and no added negative thermal expansion material is used as the foamed resin insulation material b of the foamed resin molded body 1.

[0108] For two SUS316L 2B piping (4,000mm), such as Figure 13 As shown, the foamed resin insulation material a and foamed resin insulation material b, which are the first layer of foamed resin molded body 1, are bonded to the outer surface of the pipe P using a polyurethane resin adhesive 2. The joints of the foamed resin insulation materials a and b along the circumferential direction are also bonded to each other using the polyurethane resin adhesive 2.

[0109] In addition, butyl moisture-proof tape 5 is attached to the joints in the circumferential and longitudinal directions of the foamed resin molded body 1.

[0110] The second and third layers of the insulation material are foamed resin molded bodies 1, which are water-based polyurethane foams without glass cloth and without the addition of negative thermal expansion materials. The inner surface is made of kraft paper and the outer surface is made of aluminum kraft paper sheets.

[0111] The second layer of foamed resin molded body 1 has a polyurethane adhesive 7 applied to the central part of its inner surface to a diameter of 30-50 mm, and is partially bonded to the outer surfaces of the first layer of foamed resin insulation material a and foamed resin insulation material b.

[0112] It should be noted that the joints between the second layer of foamed resin molded bodies 1 in the circumferential and longitudinal directions are unbonded joints.

[0113] In addition, similar to the first layer, butyl moisture-proof tape 5 is attached to the joints in the circumferential and longitudinal directions of the second layer of foamed resin molded body 1.

[0114] Next, for the purpose of moisture / waterproofing, a polyethylene sheet 3 is wound into a spiral shape on the outer surface of the second layer of foamed resin molded body 1, and a third layer of foamed resin molded body 1 is installed on it.

[0115] The circumferential and longitudinal joints of the foamed resin molded bodies 1 in the third layer are also bonded together using polyurethane resin adhesive 4. Butyl moisture-proof tape 5 is attached to the joints of the foamed resin molded bodies 1 in the circumferential and longitudinal directions in the third layer. For the circumferential direction, stainless steel tape is used to tighten it. The assembly tube cooling verification model is then assembled.

[0116] It should be noted that, as Figure 12 of (a), Figure 12 (b) Figure 12 As shown in (c), in order to measure the shrinkage caused by cooling, strain gauges are attached to the outer surface of the piping, the inner surface of the foamed resin insulation material a and the foamed resin insulation material b. In addition, thermocouples are also installed to obtain the temperature of each part.

[0117] In addition, in order to allow the SUS316L piping to contract during cooling, one end of the piping along its length is designated as a fixed end 8, and the other end of the piping along the other side is designated as a free end 9.

[0118] (FEM stress analysis in the 2B piping model)

[0119] FEM stress analysis was used to confirm whether the tensile thermal stress generated in the first layer of foamed resin molded body (foamed resin insulation materials a and b) when the SUS316L piping was filled with -196℃ (liquid nitrogen) caused cracks in the first layer of foamed resin molded body 1.

[0120] It should be noted that the FEM stress analysis was performed using SolidWorks Simulation, manufactured by Dassault Systèmes SolidWorks Corporation. Additionally, various physical property values ​​are provided in the table (…). Figure 14 The value shown is ).

[0121] It should be noted that, Figure 14 In this context, Θ represents temperature.

[0122] As a result of FEM stress analysis, the average generated thermal stress (tensile stress in the axial direction of the pipe) in the foamed resin molded body (foamed resin insulation material b) without the addition of negative thermal expansion material in pipe 2B is 0.48 MPa, with a safety factor of 1.5.

[0123] For a maximum tensile stress of 0.85 MPa, the safety factor is 0.8, which is less than 1.

[0124] Based on this maximum tensile stress, the foamed resin molded body 1 may develop cracks. Figure 15 ).

[0125] On the other hand, the average generated thermal stress of the foamed resin molded body (foamed resin insulation material a) with added negative thermal expansion material and integrated by two layers of glass cloth is 0.35 MPa, and the safety rate is 4.5.

[0126] For a maximum tensile stress of 1.3 MPa and a safety factor of 1.2, the calculation result is that the foamed resin insulation material a will not crack. Figure 15 ).

[0127] (Summary of cooling tests in the 2B piping validation model)

[0128] Liquid nitrogen (LN2) is introduced into pipe P for cooling until the temperature of each part stabilizes. After about 30 hours, the supply of liquid nitrogen (LN2) is stopped, and the temperature is allowed to rise naturally to room temperature.

[0129] Liquid nitrogen (LN2) was introduced into pipe P again for two cooling cycles until the temperature of each part stabilized. After about 30 hours, the temperature was allowed to rise naturally to room temperature. Then, the test specimen was disassembled to confirm cracks in the foamed resin insulation material a or b.

[0130] (Results of the 2B piping cooling verification test)

[0131] like Figure 16 , Figure 17 of (a), Figure 17 As shown in (b), in foamed resin insulation materials a or b, the temperature distribution under steady-state conditions during the cooling test is approximately equal to the FEM calculated value.

[0132] like Figure 18 As shown in (a) and (b) of 18, the results of the strain measurement during cooling confirm that the strain of SUS316L shows approximately the same behavior as that of the foamed resin insulation material a. Figure 18 (a) means that the foamed resin insulation material a follows the action of SUS316L.

[0133] On the other hand, it can be confirmed that in foamed resin insulation material b, a large strain is generated relative to SUS316L starting from the temperature of piping P at around -120°C, and foamed resin insulation material b cannot follow the strain of SUS316L. Figure 18 (b)

[0134] It should be noted that, if based on utilization Figure 12 (b) Figure 12 The temperature values ​​measured by the temperature sensors (A-H) shown in (c) are curved. Figure 17 of (a), Figure 17 As shown in curve (b), 10 in the figure represents Figure 12The horizontal positions of the pipe surface in (a) are A, B and Figure 12 The measured values ​​of the upper part C and the lower part D of the tube surface (c), 11 represents Figure 12 The measured value of point E in (c), 12 represents Figure 12 The measured value of point F in (c), 13 represents Figure 12 The measured values ​​of points G and H of (c).

[0135] The disassembly and inspection results showed that in the foamed resin insulation material a, no cracks were found in the polyurethane foam (PUF), and no deformation such as peeling was observed in the adhesive 2 between the pipe P and the first layer of foamed resin insulation material a. On the other hand, in the foamed resin insulation material b, cracks were found in the polyurethane foam (PUF), and the adhesive 2 between the pipe P and the first layer of foamed resin insulation material b showed deformation such as bulging and peeling, indicating poor adhesion to SUS316L.

[0136] like Figure 19 As shown, regarding the thermal stress near the boundary between the pipe P and the foamed resin insulation material a, which can be calculated from the strain, the average generated thermal stress (tensile stress in the axial direction of the pipe) is 0.40 MPa (strain - 2,587 μST), which is the same as the value (VonMises stress, 0.40 MPa) obtained by the previous FEM analysis. This suggests the appropriateness of this pipe cooling test and that the safety margin for the maximum VonMises stress value obtained by the previous results is greater than 1.4.

[0137] [Experimental Example 10] Cooling test of 2B piping (SUS316L) using liquid helium (LHe) (-269℃)

[0138] (2B piping cooling verification model fabrication)

[0139] like Figure 20 (a), (b) Figure 13 As shown, the piping is SUS316L based on JIS standard 2B (A is nominally 50A, outer diameter 60.5mm) × 2,000mm.

[0140] The insulation structure is designed as a three-layer structure. The insulation thickness is calculated based on the following conditions: the outer surface of the insulation material does not condense under the environmental conditions of an external air temperature of 30°C and a relative humidity of 85%, and the interface temperature between the first and second layers of the insulation material is above the liquefied natural gas (LNG) temperature (-163°C). The insulation thickness is 15mm for the first layer, 50mm for the second layer, and 50mm for the third layer.

[0141] It should be noted that the fabrication of the 2B piping cooling verification model follows the same steps as in Experiment Example 9.

[0142] To measure the shrinkage caused by cooling, strain gauges were attached to the outer surface of the piping and the inner surface of the foamed resin insulation material a. In addition, thermocouples were installed to obtain the temperature of each part.

[0143] However, a platinum / cobalt thermoelectric element capable of measuring the temperature of liquid helium (LHe) (-269°C) is installed on the piping side.

[0144] In addition, in order to allow the SUS316L piping to contract during cooling, one end is designated as the fixed end 8, and the other end is designated as the free end 9. Figure 20 ).

[0145] (FEM stress analysis in the 2B piping model)

[0146] FEM stress analysis confirmed that the tensile thermal stress generated in the first layer of foamed resin molded material (foamed resin insulation material a) when the SUS316L piping was filled with -269°C (liquid helium) caused thermal stress in the first layer of foamed resin molded material.

[0147] It should be noted that the FEM stress analysis was performed using SolidWorks Simulation, manufactured by Dassault Systèmes SolidWorks Corporation.

[0148] In addition, various physical property values ​​are used Figure 21 The values ​​shown in the table.

[0149] It should be noted that, Figure 21 In this context, Θ represents temperature.

[0150] The FEM stress analysis results are shown below. Figure 22 In the table.

[0151] The average generated thermal stress (VonMises) of the foamed resin molded body (foamed resin insulation material a) with negative thermal expansion material added to the piping 2B and made of two layers of glass cloth is 0.52 MPa, and the safety factor is 3.6.

[0152] With a maximum tensile stress of 1.73 MPa and a safety factor of 1.1, the calculation result shows that the foamed resin insulation material a will not crack.

[0153] (Summary of cooling tests in the 2B piping validation model)

[0154] First, regarding the cooling of piping P, as a pre-cooling measure, liquid nitrogen (LN2) is introduced into the piping for approximately 48 hours until the temperature of each part stabilizes.

[0155] Afterwards, the supply of liquid nitrogen (LN2) was stopped, the liquid nitrogen (LN2) filling the pipe P was forcibly extracted, and then liquid helium (LHe) was introduced to cool the pipe to -269°C and maintain this temperature for 2 hours.

[0156] Afterwards, allow the temperature to rise naturally to room temperature. Then, introduce liquid nitrogen (LN2) into pipe P again for pre-cooling, followed by formal pre-cooling using liquid helium (LHe), conducting two cooling tests.

[0157] After allowing the material to heat up naturally and return to room temperature, the test specimen is disassembled to confirm cracks and other defects in the foamed resin insulation material a.

[0158] (Results of the 2B piping cooling verification test)

[0159] like Figure 23 , Figure 24 of (a), Figure 24 As shown in (b), the temperature distribution under steady-state conditions during the cooling test is approximately equal to the FEM temperature analysis value.

[0160] like Figure 25 As shown, the results of the strain measurement during the cooling test confirm that the strain of SUS316L and the strain of foamed resin insulation material a show approximately the same behavior, that is, the foamed resin insulation material a follows the behavior of SUS316L.

[0161] The disassembly and inspection results showed that no cracks were found in the foamed resin insulation material a, and no deformation such as peeling of the adhesive 2 between the pipe P and the first layer of foamed resin insulation material a was found.

[0162] It should be noted that, Figure 24 The measurement curves 14–17 shown in (a) and (b) of 24 are based on the results obtained from... Figure 12 (b) Figure 12 The temperature values ​​measured by the temperature sensors (A-H) shown in (c) are curve-based. Figure 24 In (a) and (b) of 24, 14 represents the measured values ​​at points A and C on the piping surface, 15 represents the measured value at point E between layers 1 and 2 of the PUF cover, 16 represents the measured value at point F between layers 2 and 3 of the PUF cover, and 17 represents the measured values ​​at points G and H of the outer surface of the third layer of the PUF cover and the external air temperature.

[0163] like Figure 26As shown, regarding the thermal stress near the boundary between the pipe P and the foamed resin insulation material a, which can be calculated from the strain, the average generated thermal stress (tensile stress in the axial direction of the pipe) is 0.50 MPa (strain -3,303 μST), which is approximately the same as the value obtained by the previous FEM analysis (VonMises stress, 0.52 MPa). This suggests the appropriateness of this pipe cooling test and that the safety margin for the maximum VonMises stress value obtained by the previous results is greater than 1.3.

[0164] [Experimental Example 11] The reinforcing effect of glass cloth when the thickness of polyurethane foam (PUF) is changed.

[0165] like Figure 27 As shown, in order to minimize the thermal stress generated in the foamed resin insulation material at extremely low temperatures and prevent the formation of cracks in the polyurethane foam (PUF), there is a method to reinforce the material by integrating a fiber sheet composed of intersecting warp and weft yarns with the end of the foamed resin molded body 1 in the thickness direction.

[0166] At this point, if the distance between the glass cloths is set to L, then when L is large, it is predicted that the reinforcing effect of the glass cloth GC will be particularly weak in the center (L / 2) of the reinforced foamed resin molded body 1.

[0167] Using the thickness of the polyurethane foam (PUF), i.e. the distance L between the fiber sheets, as a parameter, an integral polyurethane foam (PUF) of fiber sheets (two layers) was formed and the coefficient of linear expansion (room temperature to -170℃) was measured. The Gompertz curve, which is a representative example of the growth curve, was used to obtain an approximate formula (correlation coefficient 0.989).

[0168] It should be noted that the fiber sheet (glass cloth) used is a product of Unitika Co., Ltd. (product number: L55MN104F, fabric type: leno weave, 2.5mm mesh).

[0169] like Figure 28 As shown, the test results confirm that if the distance L between the fiber sheets increases, the coefficient of linear expansion α increases. If L = 200 mm or more, it approaches the coefficient of linear expansion α = 51.9 ppm / K of unreinforced polyurethane foam (PUF).

[0170] To prevent cracking of polyurethane foam (PUF) at extremely low temperatures, considering the linear expansion coefficients of various metals (SUS316L, α = 10~16ppm / K), the spacing between glass cloths is assumed to be less than L = 15mm (as a linear expansion coefficient, α ≒ 20ppm / K). In integrated polyurethane foam (PUF) with L > 15mm, the linear expansion coefficient increases, and when used as the first layer of insulation material for liquid nitrogen and liquid hydrogen piping / equipment, polyurethane foam (PUF) may crack.

[0171] To avoid this situation, the following experiment was conducted.

[0172] like Figure 29 As shown in (B), fiber sheets were stacked at a spacing of L = 15 mm, and foaming and layering were performed sequentially. The glass cloth was injected into the substrate in a manner with polyurethane foam (PUF) thicknesses of t = 30 (15 / 15), 45 (15 / 15 / 15), and 60 (15 / 15 / 15 / 15) mm to create a multi-layer test body, and the coefficient of linear expansion was measured.

[0173] It should be noted that, for reference only, such as Figure 29 As shown in (A), an evaluation of the integrated method using adhesives was also conducted when the thickness of the polyurethane foam (PUF) was t = 30 (15 / 15).

[0174] like Figure 28 As shown, the coefficient of linear expansion in the multi-layer injection integrated method is 17.9, 19.2, and 19.1 ppm / K at t = 30, 45, and 60 mm, respectively, which is approximately the same as the coefficient of linear expansion α = 17.7 ppm / K of the glass cloth integrated PUF (single layer) with a thickness of t = 15 mm.

[0175] On the other hand, the polyurethane foam (PUF) with a thickness t = 30 (15 / 15) mm made using adhesive has a linear expansion coefficient of 31.0 ppm / K due to the influence of the adhesive, which is about 1.7 times that of the multilayer integrated method.

[0176] In the insulation design of piping / equipment for liquid nitrogen and liquid hydrogen, the design principle is to ensure that the interface temperature between the first layer of foamed resin insulation material and the second layer of polyurethane foam (PUF) is above the liquefied natural gas (LNG) temperature (-163°C). Therefore, as the piping size increases, the insulation thickness of the first layer of foamed resin insulation material increases. For example, in a 24B piping with an insulation thickness of 37mm, the linear expansion coefficient of the foamed resin insulation material increases (α≒27ppm / K) when the distance between the glass cloths L=37mm. At extremely low temperatures, the polyurethane foam (PUF) may crack.

[0177] On the other hand, if in a multi-layered integrated approach ( Figure 29 When a foamed resin insulation material with a thickness of t = 45 (15 / 15 / 15) mm is applied in (B), the coefficient of linear expansion does not change relative to a single layer with a thickness of L = 15 mm, thus suppressing cracks in the PUF.

[0178] [Other Implementation Methods]

[0179] Other implementation methods are described below.

[0180] <1> As an example of a molded foamed resin, polyurethane resin (PUF) is used, but polyisocyanurate (PIR) or phenolic resin foams can also be used instead. In addition, as an unfoamed resin material, unfoamed polystyrene resin, unfoamed polyethylene resin, or unfoamed polyester resin can also be used.

[0181] <2> As a material with negative thermal expansion, zirconium tungstate phosphate (Zr2WO4(PO4)2) (manufactured by Nippon Chemical Industries, Ltd.) can also be used instead of zirconium sulfate phosphate (Zr2SP2O). 12 (Manufactured by Tokyo Institute of Technology), BiNi1-xFexO3 oxide ceramic with perovskite structure composed of bismuth-nickel-iron, zirconium tungstate (ZrW2O8) (manufactured by JX Metals Co., Ltd.), silicon oxide (Li2O-Al2O3-nSiO2), zirconium phosphate (Zr(HPO4)2) (manufactured by Toa Synthetic Co., Ltd.).

[0182] <3> When multiple sheets of glass cloth with interlaced warp and weft yarns are laminated, the fiber sheets can be laminated by interlacing the warp yarns of the first sheet of glass cloth with the warp yarns of the second sheet of glass cloth at an angle. In addition, carbon fiber, aramid fiber, etc. can be selected to replace glass cloth as the material of each fiber sheet.

[0183] <4> In addition to filling unfoamed resin into a mold for foaming and curing, foamed resin molded bodies can also be formed by spraying with a sprayer.

[0184] <5> It can be an object formed as follows: for foamed resin molded bodies, and fiber sheets composed of intersecting warp and weft yarns, through... Figure 29 Method (B) involves placing glass cloth in layers within a mold, filling the mold with unfoamed resin for foaming and curing, such as... Figure 30 As shown, it is formed by embedding in layers within the thickness of the foamed resin.

[0185] It should be noted that, as described above, symbols have been used for ease of comparison with the accompanying drawings, but the present invention is not limited to the structure of the drawings based on this description. Furthermore, various embodiments are possible without departing from the spirit of the invention.

Claims

1. A foamed resin thermal insulation material composed of a foamed resin molded body which is molded by foaming an unfoamed resin material into which a negative thermal expansion material which expands in volume when the temperature decreases following volume shrinkage upon temperature increase is mixed, the foamed resin molded body being integrated in a layered state with a fiber sheet composed of warp and weft yarns which cross each other in layers.

2. The foamed resinic thermal insulation material of claim 1, wherein, The fiber sheet composed of warp and weft yarns which cross each other is integrated with the inner and outer surfaces of the foamed resin molded body.

3. The foamed resinous thermal insulation material of claim 1, wherein, A plurality of the fiber sheets are integrated with the foamed resin molded body.

4. The foamed resinic thermal insulation material according to claim 1 or 2, wherein, The unfoamed resin material is an unfoamed polyurethane resin, 5. The foamed resinous thermal insulation material of claim 1, wherein, The negative thermal expansion material is one selected from the group consisting of zirconium tungstate phosphate (Zr2W04(PO4)2), zirconium sulfate phosphate (Zr2SP2O 12 ), an oxide ceramic having a perovskite structure composed of bismuth-nickel-iron BiNi1-xFexO3, zirconium tungstate (ZrW2O8), Li2O-Al2O3-nSiO2, the unfoamed resin material is one selected from the group consisting of unfoamed polyurethane resin, unfoamed polystyrene resin, unfoamed polyethylene resin, unfoamed polyester resin, unfoamed phenol resin, and the fibrous sheet is a cloth selected from the group consisting of glass fiber, carbon fiber, aramid fiber.

6. The foamed resinous thermal insulation material of claim 1, wherein, The fiber sheet is a cloth composed of glass fibers, The unfoamed resin material is an unfoamed polyurethane resin, The fiber sheet is a cloth composed of glass fibers, In the foamed resin molded body, 3 wt% or more of a powder of cellulose nanofibers is mixed with respect to the amount of unfoamed resin filled and integrated.

7. The foamed resinous thermal insulation material of claim 1, wherein, The unfoamed resin material is an unfoamed polyurethane resin, The fiber sheet is a cloth composed of glass fibers, In the foamed resin molded body, 3 wt% or more of a powder of cellulose nanofibers is mixed with respect to the amount of unfoamed resin filled and integrated. The unfoamed resin material is an unfoamed polyurethane resin, 8. The foamed resinous thermal insulation material of claim 1, wherein, The fiber sheet is a cloth composed of glass fibers, In the foamed resin molded body, 3 wt% or more of a powder of cellulose nanofibers is mixed with respect to the amount of unfoamed resin filled and integrated. A negative thermal expansion material composed of zirconium tungsten phosphate (Zr2WO4(PO4)2) is mixed in an unfoamed polyurethane resin, and the unfoamed resin material in this state is filled into a mold in a manner in which a fiber sheet of a glass cloth composed of warp and weft yarns which cross each other is layered, and is molded by being foamed and solidified in the mold. ​ 9. A process for the production of a foamed resinous thermal insulating material, wherein, ​

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