JP4898141B2 - Manufacturing method of vacuum insulation core material - Google Patents

Description

The present invention relates to the production how the vacuum heat insulating material for the core material.

  A vacuum heat insulating material obtained by sealing a core material made of an inorganic fiber laminate in a jacket material under reduced pressure has been widely used in recent years because of its excellent heat insulating performance. As the core material, there is an organic binder type formed by attaching an organic binder such as a thermosetting resin, and an inorganic binder type formed by temporarily forming a laminate and attaching an inorganic binder to the laminate, The above organic binder type is easier to give a binder when fiberizing and laminating inorganic fibers than the above inorganic binder type, is easy to manufacture, and is the same method as the heat insulating mat used in ordinary buildings This is preferable because it can be made at a low cost.

  However, when an organic binder type core material is used as the core material of the vacuum heat insulating material, when the vacuum heat insulating material is used at a high temperature, the binder contained in the core material may decompose and gas may be generated. There is a problem that there is. In Patent Document 1, an organic binder type core material is put into a baking furnace and heated at about 400 ° C. for 1.5 hours to burn and vaporize a phenol resin as a binder, and this gas is connected in advance to a suction port of a heat insulating wall. By exhausting from the exhaust port and heating in the presence of air up to the decomposition temperature of the binder when using vacuum insulation, the organic binder is gasified, and after exhausting this gas, an excellent vacuum can be obtained It is described that a heat insulating material can be obtained.

  On the other hand, as a core material for vacuum heat insulating material using an inorganic fiber laminated body that does not use an organic binder, glass is formed by a temperature at which the fiber starts to deform slightly due to its own weight, or a load from the vertical direction during pressing. The temperature at which the fiber can be deformed, the temperature at which the cross-sectional shape of the glass fiber does not change significantly, the fiber is stretched by heat deformation of the glass fiber, and the fibers are bound together. However, Patent Document 2 discloses a vacuum heat insulating material in which a part of glass fiber is intertwined between fibers and maintains the shape. According to the document, it is preferable that the heating press is set to 480 ° C. for 5 minutes.

Further, a step of laminating glass white wool containing neither organic or inorganic binder into a predetermined shape, and the laminated glass white wool within a temperature range of 20 ° C. from the deformation point to the deformation point, 0.007 The step of heating and pressurizing at a pressure of ˜1.5 kg / cm ² for 10 minutes or more and the step of putting the molded glass white wool into a non-breathable container and evacuating and depressurizing are sequentially performed. The manufacturing method of the vacuum heat insulating material using the characteristic glass white wool is disclosed, and it is described in patent document 3 that the said heating is 400 degreeC or more and 10 minutes or more.
JP-A-5-87292 Japanese Patent No. 3580315 Special table 2003-532845 gazette

  However, when the organic binder contained in the core material is completely gasified by the method disclosed in Patent Document 1, workability is not difficult because the gasification is heated inside the wall, and the organic binder is not included. When it is used as a vacuum heat insulating material, the thermal performance of the vacuum heat insulating material does not deteriorate particularly due to long-term gasification, but it takes longer heating time, so the glass melts more than necessary and the binding between the fibers increases. However, there is a problem that the thermal performance of the vacuum heat insulating material is inferior because solid heat conduction is likely to occur.

  On the other hand, in the method disclosed in Patent Document 2, because glass fibers that do not have a binder are used from the beginning, gas is not generated and heat performance is excellent, but glass fibers are not bound together. In addition, the shape retention of the core material is inferior, and not only the workability when introduced into the jacket material is inferior, but also when used as a vacuum heat insulating material, bending tends to occur, and the vacuum heat insulating material can be used as a refrigerator or other box. However, there is a problem that sufficient thermal performance cannot be obtained due to the formation of gaps.

  Further, in the method disclosed in Patent Document 3, although gas is not generated and excellent in thermal performance, for example, heating at 400 ° C. for 30 minutes is not sufficient in shape retention of the core material as in Patent Document 2. . Therefore, although it is conceivable that the heating temperature is further increased and the heating time is further lengthened, there is a problem that it is not preferable in terms of cost.

  Moreover, in said patent document 2, 3, since inorganic fiber laminated bodies, such as glass wool which does not have a binder, are used from the beginning, an inorganic fiber laminated body is cut | disconnected to a predetermined dimension as a core material for vacuum heat insulating materials. At the same time, there was a problem of workability such that it was difficult to cut.

  The present invention has been made in view of the above problems, and its purpose is to provide excellent heat performance as a vacuum heat insulating material and good shape retention, so that there is little bending, excellent workability, and filling a box or the like. Provide a vacuum heat insulating material that does not cause gaps in the box and the like and does not deteriorate in thermal performance over time, and heats more than necessary when creating a core for vacuum heat insulating material. Therefore, the present invention is to provide a vacuum insulation material manufacturing method and a vacuum insulation material that are economically superior.

  The above object is achieved by the present invention described below. That is, the present invention is characterized in that after adding an organic binder to an inorganic fiber, it is heated and cured to form an inorganic fiber laminate, and the inorganic fiber laminate is further heated at a temperature of more than 350 ° C. and 600 ° C. or less. Provided is a method for producing a vacuum insulation core material.

In the said invention, the binder adhesion amount in the said inorganic fiber laminated body is 0.2-10 mass parts by solid content, when this inorganic fiber laminated body is 100 mass parts; Heating of the said inorganic fiber laminated body The temperature is 400 to 500 ° C .; the heating time of the inorganic fiber laminate is 5 to 30 minutes; and the heating time of the inorganic fiber laminate is M (minutes). The heating condition of the inorganic fiber laminate when the heating temperature is T (° C.) preferably satisfies the following formula 1.
M × T = 2,000 to 12,000 (Formula 1)

Moreover, in the said invention, by heating the said inorganic fiber laminated body, the binder adhesion amount of this laminated body is reduced 50% or more of the original mass by solid content; and the binder was provided to the said inorganic fiber. Then, it is preferable to set it as an inorganic fiber laminated body through the process pressurized so that a density may be set to 150-500 kg / m < ³ >, and a heating process.

  According to the present invention, even when an organic binder type core material is used as the core material of the vacuum heat insulating material, the generation of gas in the vacuum heat insulating material is extremely small, and the heat insulating property is excellent for a long time, producing a vacuum heat insulating material. The core material for a vacuum heat insulating material that is excellent in workability at the time can be advantageously provided in terms of production cost.

Next, the present invention will be described in more detail with reference to the best mode for carrying out the invention.
The feature of the present invention is that after an organic binder (hereinafter sometimes simply referred to as “binder”) is applied to the inorganic fiber, it is cured by heating to form an inorganic fiber laminate, and the inorganic fiber laminate further exceeds 350 ° C. and 600 ° C. It is to heat at the following temperature.

  The inorganic fiber used in the present invention is not particularly limited, for example, glass wool, glass fiber, alumina fiber, silica alumina fiber, silica fiber, rock wool, silicon carbide fiber and the like. Among these, it is preferable to use glass wool because it has excellent heat insulation performance and is relatively inexpensive. Moreover, it is also possible to mix and use an organic fiber if it is a small amount in an inorganic fiber. Since glass wool is preferable as the inorganic fiber used in the present invention, the present invention will be described below using glass wool as a representative example of inorganic fiber.

  It is preferable that the average diameter of the glass fiber which comprises the said glass wool is 1-5 micrometers. If the value is less than 1 μm, the productivity of glass wool is inferior, resulting in high costs, and the strength after molding is inferior. On the other hand, if the value exceeds 5 μm, the thermal performance of the finally obtained vacuum heat insulating material itself is lowered, which is not preferable.

  In the present invention, the glass wool is matted (laminated body) by attaching a binder to the glass wool and heat-treating it to cure the binder. Here, any conventionally known organic binder can be used as the binder, but preferred binders are phenol resin-based, epoxy resin-based and acrylic resin-based binders. A phenol resin binder is an aqueous solution of a phenol resin, and is a material well known in the art. A phenol resin is an initial condensate of phenol and formaldehyde. The phenol resin binder used in the present invention is mainly a resin such as a phenol resin, but it is preferable to use other urea resins and silane coupling agents, particularly aminosilane coupling agents, but other additives having a low molecular weight. The agent is preferably used in a small amount because it is easily gasified in the vacuum heat insulating material finally obtained.

The binder is applied to the glass wool by spraying or the like following the production of the glass wool, and the glass wool is pressurized to a predetermined density and thickness and heated to cure the binder to form a mat (laminate). A method of attaching the binder to glass wool, a method of matting, a method of curing the binder, and the like may be methods well known in the art, and the pressurization is performed for glass wool (mat) in the range of 150 to 500 kg / m ³ . It is preferable to compress so that it may become a density. When the density is less than 150 kg / m ³ , the surface smoothness of the resulting core material is inferior, so that the surface smoothness when used as a vacuum heat insulating material is inferior. A gap is formed in the film, and the thermal performance is inferior. On the other hand, if the density exceeds 500 kg / m ³ , not only will the equipment be large, but the fibers will be destroyed and become powdery. On the contrary, the thermal performance of the vacuum heat insulating material cannot be obtained, which is not preferable.

  The amount of the binder attached to the glass wool mat is preferably an amount occupying 0.2 to 10 parts by mass, more preferably 0.5 to 3 parts by mass, when the glass wool mat containing the binder is 100 parts by mass. More preferably, it is a part. If the solid content of the binder is less than 0.2 parts by mass, the mat obtained by the adhesion of the binder is bulky and the mat is flexible. This is not preferable because it is difficult to fill the workpiece. On the other hand, when the adhesion amount exceeds 10 parts by mass, excess binder adheres to the glass wool, so that gas is easily generated in the vacuum heat insulating material from the core material made of the glass wool. It is not preferable because the heat insulation performance is inferior.

  The core material for a vacuum heat insulating material according to the present invention is characterized in that the glass wool mat obtained as described above is further heated at a temperature of more than 350 ° C. and 600 ° C. or less. A particularly preferred heating temperature is 400 to 500 ° C. When the heating temperature is 350 ° C. or less, the organic binder remains at a rate exceeding about 1 part by mass per 100 parts by mass of the glass wool mat (core material), and volatilization removal of low molecular weight components in the binder adhering to the mat is insufficient. Inconveniences such as deterioration of long-term thermal performance may occur. On the other hand, if the heating temperature exceeds 600 ° C., the energy cost for heating is increased, which is economically undesirable, and since the binder hardly remains, the strength of the core material is reduced and the handling property is inferior. However, in this case, although the strength is improved, the thermal performance when used as a vacuum heat insulating material is inferior.

  In addition, because the heating temperature is in the range of 400 to 500 ° C., the adhesion amount of the binder becomes 1 part by mass or less per 100 parts by mass of the glass wool mat (core material), and part of the glass wool is fused to each other. Although the amount of residual organic binder is small, it is possible to maintain good handleability of the core material obtained by partial fusion of the glass fibers. Therefore, in the present invention, the amount of residual binder in the core material is 1 part by mass or less, preferably 0.1 to 0.5 parts by mass per 100 parts by mass of the mat (core material). Such heating can be performed by electric heating, combustion heating of kerosene, gas or the like using a normal heating furnace equipped with rolls and a conveyor device.

  In the present invention, the heating time of the mat is also important, and heating for 5 minutes or more is necessary even when the heating temperature is around 600 ° C., and about 30 minutes is necessary when the heating temperature is around 350 ° C. Therefore, in the present invention, when the heating temperature is within the above range, a heating time of 5 to 30 minutes is preferable.

More preferable heating conditions satisfy the following formula 1 when the heating time of the laminate is M (minutes) and the heating temperature of the laminate is T (° C.).
M × T = 2,000 to 12,000 (Formula 1)
If the above value is less than 2,000, volatilization removal of the binder adhering to the mat is insufficient, the binder remains exceeding 1 part by mass per 100 parts by mass of the glass wool mat (core material), and the vacuum heat insulating material When used as a core material, if the vacuum heat insulating material is used in a high temperature atmosphere, the heat insulating property of the vacuum heat insulating material due to gasification of the residual binder may be lowered. On the other hand, if the above value exceeds 12,000, energy cost for heating is required, which is not economically preferable, and the binder is almost volatilized and a part of glass wool is fused, but the strength of the core material is low. When it falls and it is inferior to handleability, glass mutually melt | fuses conversely, In this case, although the intensity | strength improves, the heat performance as a vacuum heat insulating material is inferior, and is unpreferable.

  In addition, in the range of 6,000-10,000 in the said Formula 1, the quantity of a residual binder tends to be 0.1-0.5 mass part per 100 mass parts of mat | matte (core material), and a part of glass wool Are melt-bonded to each other, and the remaining amount of the binder is small, the resulting core material has good handleability, and the obtained vacuum heat insulating material has excellent thermal performance.

  In the present invention, it is preferable that the glass wool mat is heated to reduce the binder adhering to the mat by 50% by mass or more of the original mass in terms of solid content. When the reduction rate is less than 50% by mass, the amount of heat in the heating is small, so that not only the binder component cannot be efficiently reduced using the heat of combustion caused by the burning of the binder, but also the low molecular weight component of the binder. Such a volatile component is not removed, and the thermal performance of the obtained vacuum heat insulating material is inferior, which is not preferable.

  The vacuum heat insulating material of this invention is obtained by enclosing the core material obtained by the manufacturing method of the said invention in the jacket material for vacuum heat insulating materials. As the jacket material for the vacuum heat insulating material, a resin film such as polyester, polyethylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polypropylene, polyamide, etc., laminated with an aluminum foil, or a film obtained by depositing aluminum on the above film is preferable. Used.

  Moreover, the manufacturing method itself of a vacuum heat insulating material may be a known method. As an example, a mold having an upper mold and a lower mold and having an exhaust port exhausted by a vacuum pump is prepared, and one of the molds is formed on the cavity inner surface formed by the upper mold and the lower mold. Arranges a gas barrier outer covering material having an exhaust and sealing tube, for example, an aluminum-deposited high-density polyethylene film, and arranges the vacuum insulation core material of the present invention between them, then closes the mold and moves up and down 2 Fusing the peripheral part of the outer cover material of the sheet, degassing through the tube, and then sealing the tube and demolding while keeping the internal pressure of the gas barrier outer cover material to 10.0 Pa or less Thus, a vacuum heat insulating material is obtained. The size and thickness of the obtained vacuum heat insulating material can be arbitrarily changed depending on the application.

The density of the vacuum heat insulating material is preferably 150 to 300 kg / m ³ . If the density of the vacuum heat insulating material is less than 150 kg / m ³ , the thickness of the vacuum heat insulating material is likely to decrease thereafter, and after filling the box with the vacuum heat insulating material, a gap is not preferable. If it exceeds 300 kg / m ³ , not only is the mass increased and this is disadvantageous in cost, but the thermal conductivity of the solid is increased and the thermal performance is inferior.

Next, the present invention will be described more specifically with reference to examples and comparative examples.
Example 1
A mat (500 × 1,500 mm) laminated with glass binder with an average fiber diameter of 4 μm sprayed with an aqueous phenol resin binder solution with a solid content of 2% by mass in a two-fluid system with air and with the binder uniformly attached in the thickness direction. ) Is heated and pressed under conditions of 250 ° C. and oven residence time of about 30 seconds while being sandwiched at a compression density of 150 kg / m ³ by an upper and lower conveyor in a hot air passing oven, and the amount of binder attached is solid per 100 parts by weight of glass wool 2 parts by mass of an inorganic fiber laminate (mat) was obtained. Furthermore, this inorganic fiber laminated body was heat-processed at 500 degreeC for 20 minutes as shown in Table 1, and the core material for vacuum heat insulating materials was obtained. The binder adhesion amount after heating was 0.2 parts by mass per 100 parts by mass of glass wool mat.

The above core material is laminated on two plies, inserted into a bag-like jacket material having high gas barrier properties for a vacuum heat insulating material, and gas is supplied so that the pressure in the bag becomes 1.0 Pa with a vacuum sealing device. After suction, the opening of the bag was heat-pressed to obtain a vacuum heat insulating material of the present invention having a thickness of 11 mm and a density of 207 kg / m ³ . The handling of the core material of this vacuum heat insulating material, the fused state of the glass fiber, the initial thermal conductivity (λ), the thermal conductivity after the accelerated test (λ), the surface smoothness, and the quality of the vacuum heat insulating material Is shown in Table 1 below.

Examples 2-7, Comparative Examples 1-5
The vacuum heat insulating materials of Examples 2 to 7 and Comparative Examples 1 to 5 were produced in the same manner as in Example 1 under the conditions described in Table 1 below, and their performance was examined. The results described in Table 1 were obtained.

1. <Heat treatment>
The heat treatment at 300 ° C. or lower was carried out in a hot air circulation type electric heating furnace, and the heat treatment above 300 ° C. was carried out in a radiant electric heating furnace. A hot air circulation type heating furnace can be used for the heat treatment up to 300 ° C., and heating can be performed relatively uniformly. However, the radiation type heating furnace tends to reduce the amount of binder on the surface.
2. <Binder solid content after heating (parts)>
The core material was heated at 500 ° C. for 30 minutes, the mass of the core material before heating and the mass of the core material after heating were measured, and the difference was defined as the solid content adhesion amount.

3. <Handling of core material>
It is important that the core material is easy to handle during the actual vacuum packaging operation, and it was judged from the droop test result. In the sagging test, a vacuum heat insulating core material having a length of 1,500 mm and a width of 500 mm is sent to an inclined surface inclined at 45 °, and the leading end of the core material in contact with the inclined surface is in contact with the inclined surface. The distance between the slope point and the slope point (point where the slope starts) was measured.
Dripping test measurement result ◎: 400 mm or more ○: 300 mm or more and less than 400 mm △: 200 mm or more and less than 300 mm ×: less than 200 mm

4). <Fused state of glass fiber>
The intersection of glass wool was observed with SEM, and the number of fusions and the degree of fusion were observed.
5). <Λ>
Thermal conductivity at an average temperature of 25 ° C. measured by a thermal conductivity meter.
6). <Initial λ>
Thermal conductivity measured within 72 hours, held at room temperature after vacuum packaging.
7). <Λ after acceleration test>
Thermal conductivity measured after holding a vacuum heat insulating material in a thermostatic chamber for 2 months at 70 ° C. and 50% RH.

8). <Surface smoothness>
Surface smoothness of vacuum heat insulating material having a size of 1,500 mm in length x 500 mm in width.
A: There are few irregularities and the depth of the recess is less than 1 mm. O: There are slight irregularities and the depth of the recess is 1 mm or more and less than 2 mm. Δ: The depth of the recess is 1 mm or more and less than 2 mm. Partially 2mm deep
Those having the above x: those having large irregularities and most of the concaves having a depth of 2 mm or more. <Judgment of pass / fail of vacuum insulation>
◎: Excellent ○: Pass ×: Fail

  As described in Table 1 above, the vacuum heat insulating material of the present invention has good handling properties of the core material, and λ is 3 mW / mK or less after the acceleration test, and has excellent heat insulating performance over a long period of time. It is clear.

  According to the present invention, even when an organic binder type core material is used as the core material of the vacuum heat insulating material, the generation of gas in the vacuum heat insulating material is extremely small, and the heat insulating property is excellent for a long time, producing a vacuum heat insulating material. The core material for a vacuum heat insulating material that is excellent in workability at the time can be advantageously provided in terms of production cost.

Claims (6)

After imparting an organic binder to the inorganic fiber, pressurization is performed so that the density is 150 to 500 kg / m ³ and heating is performed to cure the binder, and the binder adhesion amount after the heat curing is obtained. An inorganic fiber laminate that is 0.5 to 3 parts by mass per 100 parts by mass of the laminate is obtained, and the inorganic fiber laminate is further heated at a temperature of more than 350 ° C. and 600 ° C. or less. Manufacturing method of core material.   The manufacturing method of the core material for vacuum heat insulating materials according to claim 1, wherein the heating temperature of the inorganic fiber laminate is 400 to 500 ° C.   The manufacturing method of the core material for vacuum heat insulating materials according to claim 1 or 2, wherein the heating time of the inorganic fiber laminate is 5 to 30 minutes. The heating condition of the inorganic fiber laminate when the heating time of the inorganic fiber laminate is M (minutes) and the heating temperature of the inorganic fiber laminate is T (° C) satisfies the following formula 1. 4. The method for producing a core material for a vacuum heat insulating material according to any one of 3.
M × T = 2,000 to 12,000 (Formula 1)   The core for a vacuum heat insulating material according to any one of claims 1 to 4, wherein by heating the inorganic fiber laminate, the organic binder adhesion amount of the laminate is reduced by 50% or more of the original mass in solid content. A method of manufacturing the material.   The amount of residual binder in the core material obtained by heating the inorganic fiber laminate is 0.1 to 1 part by mass per 100 parts by mass of the core material, according to any one of claims 1 to 5. Manufacturing method of core material for vacuum heat insulating material.