JP4898157B2 - 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 enclosing a core material composed of an inorganic fiber laminate in an outer cover material and sealing under reduced pressure has been widely used in recent years because of its excellent heat insulating performance. As the core material, an organic binder type formed by attaching an organic binder such as a thermosetting resin to the inorganic fiber laminate, an inorganic binder type formed by attaching an inorganic binder to the inorganic fiber laminate, and a binder are not used. The type is known. Compared with an inorganic binder type core material, the organic binder type core material is less likely to cause migration of the binder component at the time of curing, and can easily adhere the binder to the inorganic fibers relatively uniformly, and has good moldability. Moreover, the organic binder type core material has an advantage that it can be provided at low cost because it can be produced by the same method as the heat insulating mat used in ordinary buildings.

  However, the vacuum heat insulating material using the organic binder type core material may generate gas in the vacuum heat insulating material due to decomposition of the organic binder at the high temperature when used at high temperature. There was a problem that the thermal performance of the vacuum heat insulating material deteriorated. For this reason, in Patent Document 1, a glass fiber mat (core material) to which a phenol resin as an organic binder is attached is placed in a baking furnace, heated at about 400 ° C. for 1.5 hours, and the phenol resin is burned and vaporized. It is described that a vacuum heat insulating material can be obtained by exhausting the vaporized gas from an exhaust port previously connected to the suction port of the heat insulating wall and then performing vacuum exhaust.

Moreover, if the use of the vacuum heat insulating material is limited to the use at a temperature of 100 ° C. or lower, the amount of gas generated in the vacuum heat insulating material can be reduced even in the case of a vacuum heat insulating material using an organic binder type core material. Patent Document 2 describes that a desired degree of vacuum can be maintained for a vacuum heat insulating material over a long period of time if gas can be adsorbed with a getter agent or the like.
JP-A-5-87292 JP 2001-108186 A

  However, when the organic binder adhering to the core material is gasified by the method disclosed in Patent Document 1, it is necessary to heat the core material at 400 ° C. or higher for a long time. Therefore, the method disclosed in Patent Document 1 uses a large amount of energy to increase the temperature of the core material, is not preferable in terms of cost, and requires a long heating time for gasifying the organic binder. There was a problem that the productivity of was inferior.

  Moreover, although the method described in Patent Document 1 is filled with a core material in a wall, heated, and evacuated as it is, the workability is relatively good. However, the core material is included in a jacket material such as a laminate film. In the vacuum heat insulating material, the core material is once heated at a high temperature of 400 ° C. or higher to gasify the organic binder, and then the core material is encapsulated in the jacket material. In the case of continuous production by such a method, heating equipment at a high temperature becomes large, which is not preferable.

  On the other hand, if the use of the vacuum heat insulating material is limited to that used at a temperature of 100 ° C. or less, the vacuum heat insulating material using the organic binder type core material can suppress the generation of gas, but the vacuum heat insulating material can be used for a long time. When used for a long time, gas is generated in the vacuum heat insulating material, thereby lowering the degree of vacuum of the vacuum heat insulating material, resulting in inferior thermal performance of the vacuum heat insulating material.

  Therefore, the present invention has been made in view of the above problems, and the object of the present invention is to provide gas in the vacuum heat insulating material even when an organic binder type core material is used as the core material of the vacuum heat insulating material. An object of the present invention is to advantageously provide a core material for a vacuum heat insulating material that is extremely low in generation, excellent in heat insulating properties over a long period of time, and excellent in workability when manufacturing a vacuum heat insulating material in terms of production cost.

  The above object is achieved by the present invention described below. That is, the present invention provides a vacuum heat insulating material characterized in that after adding a phenol resin 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 220 to 350 ° C. A method for producing a core material is provided.

In the said invention, the binder adhesion amount in the said core material for vacuum heat insulating materials is 0.1-5 mass parts by solid content, when this core material is 100 mass parts; The heating temperature is 240 to 300 ° 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), and the inorganic fiber laminate The heating condition of the inorganic fiber laminate when the heating temperature is T (° C.) satisfies the following formula 1; at the time of the heat curing, the density of the inorganic fiber laminate is 90 to 300 kg / m ^3. It is preferable to apply pressure.
M × T = 1,500 to 9,000 (Formula 1)

  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 adding a phenol resin binder (hereinafter sometimes referred to simply as “binder”) to the inorganic fiber, it is cured by heating to form an inorganic fiber laminate, and the inorganic fiber laminate is further heated at 220 to 350 ° C. It is in heating.

  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, the 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 binder used in the present invention is mainly composed of a phenol resin, but other urea resins and silane coupling agents, particularly aminosilane coupling agents are preferably used in combination, but other additives having a low molecular weight are finally obtained. It is preferable that the amount used is small because it is easily gasified in the vacuum heat insulating material.

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 compressed between heating rolls to obtain a predetermined density and thickness, and the binder is cured 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 density of the inorganic fiber laminate is 90 to 300 kg / m ³ during the heat curing. More preferably, pressurization so as to be 140 to 200 kg / m ³ is more preferable in combination with the heating of the inorganic fiber laminate described later, because the heat insulation performance of the vacuum heat insulating material is improved. When the density is less than 90 kg / m ³ , it may be difficult to obtain higher thermal performance in the finally obtained vacuum heat insulating material. On the other hand, when the density exceeds 300 kg / m ³ , the glass wool mat is pressed. The equipment becomes large, and the glass wool is broken to become powdery, and it may be difficult to obtain higher thermal performance in the vacuum heat insulating material finally obtained.

  The amount of the binder attached to the glass wool is preferably 0.1 to 5 parts by mass, more preferably 0.3 to 3 parts by mass when the glass wool is 100 parts by mass. If the solid content of the binder is less than 0.1 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 5 parts by mass, excess binder adheres to the glass wool, so that the low molecular weight components and the like are removed from the core material made of the glass wool by heating as described later. As a result, the heat insulating performance of the vacuum heat insulating material is deteriorated, which is not preferable.

  In the present invention, the glass wool mat obtained as described above is further heated at 220 to 350 ° C. to obtain a core material for a vacuum heat insulating material. A particularly preferable heating temperature is 240 to 300 ° C. When the heating temperature is less than 220 ° C., volatilization removal of low molecular weight components and the like in the binder adhering to the mat is insufficient, and the heat insulating performance of the finally obtained vacuum heat insulating material is lowered. On the other hand, if the heating temperature exceeds 350 ° C., the energy cost for heating is increased, which is economically undesirable, the volatilization of the resin component of the binder increases, the strength of the core material decreases, and the handling property is inferior. There is a case. 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 although it depends on the amount of the binder before heating, heating for 5 minutes or more is preferable even when the heating temperature is around 350 ° C., and the heating temperature is around 220 ° C. Then, about 30 minutes is preferable. Therefore, in the present invention, when the heating temperature is within the above range, a heating time of 5 minutes 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 = 1,500 to 9,000 (Formula 1)
If the above value is less than 1,500, the removal of low molecular weight components in the binder attached to the mat is insufficient, while if the above value exceeds 9,000, the energy cost for heating It is not economically preferable, and volatilization of the resin component of the binder is increased, and the strength of the core material may be reduced, resulting in poor handling.

  The core material obtained by heating the laminate preferably has a reduction rate of 10% by mass or less of the solid content of the binder by heating described below. When the reduction rate exceeds 10% by mass, when the core material is used as the core material of the vacuum heat insulating material, gas generation is increased in the obtained vacuum heat insulating material, and heat insulation is achieved in the use of the vacuum heat insulating material over a long period of time. Performance may degrade excessively. In the core material obtained as described above, components that are easily gasified in the binder contained in the core material (uncured phenol resin, low molecular weight components, low molecular weight impurities, etc.) are removed. When used as a core material of a vacuum heat insulating material, generation of gas in the vacuum heat insulating material can be suppressed.

In addition, in the above, the measuring method of the decreasing rate of binder solid content is as follows.
The vacuum heat insulating material filled with the core material according to the present invention is unpacked, the core material is taken out, heated in a heating furnace at 240 ° C. for 30 minutes, and the resin reduction rate is measured. The reduction rate is 10% by mass or less, desirably 5% by mass or less.
Binder reduction rate (%) = (ab) / (ac) × 100
a is a mass at a moisture content of 0% of the core material, b is a mass after heating a at 240 ° C. for 30 minutes, and c is a residual mass when the binder is burned off by heating a at 500 ° C. for 30 minutes. .
Moreover, the measurement of the adhesion amount of the binder solid content to the mat was performed by heating the core material at 500 ° C. for 30 minutes and measuring the mass of the core material before heating and the mass of the core material after heating.

  The amount of the binder attached to the vacuum heat insulating material core is preferably 0.1 to 5 parts by mass in terms of solid content when the vacuum heat insulating material core is 100 parts by mass, and 0.3 to 2 masses. More preferably, it is a part. If the solid content of the binder is less than 0.1 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 5 parts by mass, it is considered that a low molecular weight component or the like remains from the core material made of the glass wool even by the heating due to the excessive binder adhering. The heat insulation performance of the vacuum heat insulating material is inferior, which is not preferable.

  The vacuum heat insulating material of the present invention is obtained by enclosing the core material of the present invention in a vacuum heat insulating material. As the jacket material for the vacuum heat insulating material, polyester, polyethylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polypropylene, polyamide and other resin films, kraft paper and the above film laminated, and the above film laminated with aluminum foil Those obtained by depositing aluminum on the above film are preferably used.

  Moreover, the manufacturing method itself of a vacuum heat insulating material may be a known method. As an example, an upper mold and a lower mold are used, and a mold having an exhaust port exhausted by a vacuum pump is prepared in either one of the molds, and an inner surface of a cavity formed by the upper mold and the lower mold is prepared. One is a gas barrier sheath material having an exhaust and sealing tube, for example, an aluminum-deposited high-density polyethylene film, and the vacuum insulation core material of the present invention is placed between them. The peripheral portions of the two jacket materials are fused, deaerated through the tube, the internal pressure of the gas barrier jacket material is set to 10.0 Pa or less, and then the tube is sealed and demolded. 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 , and the core material in the vacuum heat insulating material has a decreasing rate of 10% by mass or less of the phenol resin binder when heated at 240 ° C. for 30 minutes. Preferably there is. 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 solution of phenol resin binder with a solid content of 10% 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 3 minutes while being sandwiched by a hot air passing oven so that the density of the mat is 64 kg / m ³ with an upper and lower conveyor, and the binder adhesion amount is 100% of glass wool. 4 mass parts inorganic fiber laminated body was obtained by solid content per mass part. Furthermore, this inorganic fiber laminated body was heat-processed at 240 degreeC for 30 minutes as shown in Table 1, and the core material for vacuum heat insulating materials was obtained. The amount of binder adhering after heating was 3.1 parts by mass per 100 parts by mass of the core material, and when the obtained core material was heated at 240 ° C. for 30 minutes, the binder reduction rate was confirmed. It was 3.8% by mass.

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 10 mm and a density of 200 kg / m ³ . Table 1 below shows the initial thermal conductivity (λ) of this vacuum heat insulating material, the heat conductivity (λ) after one month, and the quality of the vacuum heat insulating material.

Examples 2-10, Comparative Examples 1-3
The vacuum heat insulating materials of Examples 2 to 10 and Comparative Examples 1 to 3 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.
In all of the above examples and comparative examples, no getter agent for a vacuum heat insulating material was used.

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. <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.
A: Excellent (the distance is 800 mm or more (including the case where it does not touch)
○: Good (the distance is 600 mm or more and less than 800 mm)
Δ: Slightly defective (the distance is 400 mm or more and less than 600 mm)
X: Defect (the distance is less than 400 mm)

3. <Λ>
Thermal conductivity at an average temperature of 25 ° C. measured by a thermal conductivity meter.
4). <Initial λ>
Thermal conductivity measured within 72 hours, held at room temperature after vacuum packaging.
5). <Λ after acceleration test>
Thermal conductivity measured after holding in a constant temperature and humidity chamber for 1 month at 70 ° C. and 50% RH.
6). <Judgment of pass / fail of vacuum insulation>
○: 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 the binder solid content reduction rate in the heating evaluation at 240 ° C. for 30 minutes is as low as 10% by mass or less. Therefore, after the acceleration test, λ is 7 mW / mK or less, and it is clear that the thermal insulation performance is excellent over a long period.

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 (5)

  After adding a phenol resin binder to the inorganic fiber and setting the binder adhesion amount to 1 to 4 parts by mass per 100 parts by mass of the inorganic fiber, heat curing is performed to obtain an inorganic fiber laminate, and the inorganic fiber laminate is further heated to 220 to 350 ° C. Of the core material for vacuum heat insulating material, wherein the amount of the binder attached after heating is 0.3 to 2 parts by mass per 100 parts by mass of the obtained core material for vacuum heat insulating material Production method.   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 240 to 300 ° 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 conditions of the said inorganic fiber laminated body when the heating time of the said inorganic fiber laminated body is set to M (minute), and the heating temperature of an inorganic fiber laminated body is set to T (degreeC) satisfy | fill following formula 1. The manufacturing method of the core material for vacuum heat insulating materials of any one of these.
M × T = 1,500 to 9,000 (Formula 1) The manufacturing method of the core material for vacuum heat insulating materials of Claim 1 which pressurizes an inorganic fiber laminated body so that a density may be set to 90-300 kg / m < ³ > at the time of the said heat-hardening.