JPH10110056A - Production of foamed heat insulating material and heat-insulated box made therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a foamed heat-insulating material which has such a blowing agent composition that it can give a stable stock solution in which the blowing agent, is homogeneously dissolved and does not separate and can give a rigid polyurethane foam having fine cells and therefore having improved heat insulation properties. SOLUTION: A rigid polyurethane foam as a heat insulating material is formed by mixing a first stock solution prepared by mixing an organic isocyanate with a blowing agent comprising a substance which is inert thereto, has a vapor pressure of at least atmospheric pressure at ordinary temperature and is gaseous at the temperature of the stock solution with a second stock solution prepared by mixing a polyol with a foam stabilizer, a catalyst, a blowing agent comprising a substance which has a vapor pressure of at least atmospheric pressure at ordinary temperature and is liquid at the temperature of the stock solution and optionally water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a foamed heat insulating material which is a rigid polyurethane foam which constitutes a heat insulator by filling a gap between an inner box and an outer box of a refrigerator, and a method for producing the same. The present invention relates to a heat-insulating box using a heat-insulating body made of a foamed heat-insulating material.

[0002]

2. Description of the Related Art Conventionally, an insulated box such as a refrigerator is
A rigid polyurethane foam with excellent heat insulation is injected and foamed into the gap formed between a bent metal product (outer box) such as an iron plate as an outer shell and a resin molded product (inner box) as an inner shell. It is formed by using a heat insulator constituted by this, and in order to ensure excellent heat insulating properties of the rigid polyurethane foam constituting the heat insulator,
Monochlorotrifluoromethane (hereinafter, referred to as CFC-13), which is a chlorofluorocarbon (hereinafter, referred to as CFC), is used as a foaming agent for the rigid polyurethane foam. In recent years, in order to protect the global environment, 1,1-dichloro-1-fluoro which is a hydrochlorofluorocarbon (hereinafter referred to as HCFC), which can significantly suppress the ozone layer destruction rate, as an alternative foaming agent for CFC-13. Ethane (hereinafter, HCFC-141b)
Alternatively, 1,1-dichloro-2,2,2-trifluoroethane (hereinafter, HCFC-123) or the like is used.

[0003] However, since chlorine which destroys the ozone layer together with hydrogen remains in the molecules of these blowing agents, hydrofluorocarbons (hereinafter referred to as HFCs) and hydrocarbons containing no chlorine in the molecules are included. (Hereinafter referred to as HC) has been proposed as a foaming agent for rigid polyurethane foams.
1,1,3,3-pentafluoropropane (hereinafter HF)
C-245fa) or 1,1,1,4,4,4
-Hexafluorobutane (hereinafter, HFC-356mff
JP-A-2-235982 discloses a method for producing a rigid polyurethane foam using HFCs as a foaming agent, and JP-A-3-295882 discloses a method for producing a rigid polyurethane foam using a hydrocarbon such as cyclopentane as a foaming agent. −
No. 152160.

[0004] The method of using the heat insulator composed of the rigid polyurethane foam disclosed in the above publication as a heat insulating material for refrigerators is the same as CFC or HCFC containing chlorine in the molecule. The method is as follows. It is. (1) a mixture of an organic isocyanate having a plurality of isocyanate groups (also referred to as isocyanate) and another substance (hereinafter, referred to as an isocyanate solution), and (2) one or more polyols having a plurality of hydroxy groups, A mixed solution in which a tertiary amine is used in combination with an organic metal or the like as a catalyst in some cases, a surfactant having a siloxane group or the like as a foam stabilizer, and water is dissolved or dispersed in some cases as a foaming agent (hereinafter, referred to as a foaming agent) Premix liquid)
And (3) using a mixing device such as a high-pressure foaming machine (1).
And the two liquids of (2) are mixed, and (4) the mixed liquid of (3) is injected into the gap between the inner box and the outer box of the refrigerator and then filled by foaming and expansion. Used for

[0005] As described above, the foaming agent used for the rigid polyurethane foam is in a premixed state with a polyol or the like because it reduces the number of working steps and ensures the stability of dissolution by the surfactant. When a heat insulating material is formed, when it is mixed with an isocyanate liquid, which is another raw material liquid, by using a mixing device such as a high-pressure foaming machine, a foaming agent is vaporized and foamed by reaction heat generated at the time of mixing, and the inside of a refrigerator is formed. The gap between the box and the outer box is filled while foaming to form a heat insulator.

[0006]

A foaming agent for a rigid polyurethane foam which is a conventional foamed heat insulating material as described above,
HFCs or hydrocarbons that do not contain chlorine that destroys the ozone layer in their molecules are used, but these generally have high thermal conductivity, and rigid polyurethane foams using these are made of conventional HCFC or CFC. The heat insulating property was lower than that used as a foaming agent.

Therefore, in order to improve the heat insulating property, for example, when forming a heat insulator used in a refrigerator, cells (closed cells: spaces where foaming gas is stored) formed in the molded product (heat insulator) are formed. It is conceivable that the foamed gas in the region (2) is made of a material having a low thermal conductivity, and cyclopentane is used as a rigid polyurethane foam as a HFC or hydrocarbon having a low thermal conductivity in a gaseous state and containing no chlorine in a molecule. It is preferable to use a foaming agent, and it is considered that heat transfer due to radiation can be suppressed by making the cells finer in order to further improve the heat insulating property.

[0008] In order to suppress heat transfer due to radiation by miniaturization of the cell, in addition to optimizing the material composition, it is also necessary to send a raw material liquid such as a premix liquid to a mixing device such as a high-pressure foaming machine. By stabilizing the supply amount to the pump, or by pressurizing the inside of the stock solution tank with dry air or nitrogen used for the purpose of suppressing the vaporization of the foaming agent due to the reduced pressure of the premix liquid, It is also important that these gases be dissolved in the stock solution. In other words, after mixing the premix liquid and the isocyanate liquid using a mixing device such as a high-pressure foaming machine, instantaneously when they are released into the atmosphere, a myriad of fine bubbles generated by vaporization of the dissolved gas are generated during the mixing reaction. If the gas of the foaming agent generated by heat is taken in, the gas by vaporization will not concentrate on a specific cell and generate a large cell, and the obtained rigid polyurethane foam has an extremely fine and uniform cell structure be able to. If the gas does not dissolve or is very small, the cell undergoes a growth process that involves a failure such as destruction or fusion during the growth process of the cell, so that only an enlarged cell can be obtained. Therefore, the stock solution of the rigid polyurethane foam housed in the stock solution tank is reduced to 0.
Applying a pressure of 3 to 2.0 kg / cm ² is important for improving the heat insulating property.

[0009] A foaming agent, HFC or hydrocarbon of a rigid polyurethane foam, which is a conventional foamed heat insulating material, has poor compatibility with a polyol. Therefore, when it is mixed with a polyol or the like, the foaming agent is not completely dissolved but dispersed in a liquid. A cloudy state can be easily obtained, and a fine cell structure can be secured. However, if the stirring of the premix solution is insufficient, the foaming agent in the premix solution separates, the vaporization of the foaming agent becomes uneven, and concentrates locally, resulting in a rigid polyurethane foam having a huge cell structure. In addition, the air diffusion rate of the foaming agent also increases, leading to quality instability accompanied by a decrease in the efficiency of foaming. As a result, when foaming is performed at the same injection amount in the mold, filling due to a decrease in foaming ratio is performed. There was a risk of increasing the amount. For this reason, there is a problem that the premix liquid must be secured using a limited type of polyol or foam stabilizer at the expense of some properties in order to dissolve the foaming agent in the premix liquid. there were.

In order to ensure the solubility of the foaming agent, it is conceivable to reduce the dissolved amount of the foaming agent. However, for example, in order to prevent the filling amount from increasing at the time of filling the gap between the inner box and the outer box, It is necessary to increase the amount of water that reacts with the organic isocyanate to generate CO ₂ that becomes a foaming gas.
However, in the gas component of the cell of the rigid polyurethane foam obtained by this method, the concentration of CO ₂ having high thermal conductivity increases and the heat insulating property is reduced, and the refrigerator to which this is applied is used. , There is a risk that the power consumption will be increased.

The present invention has been made to solve the above-mentioned problems, and has a foaming agent composition capable of uniformly dissolving a foaming agent and obtaining a stable stock solution free from separation and the like. It is an object of the present invention to provide a method of manufacturing a foamed heat insulating material capable of improving the heat insulating property by further miniaturizing the cells, and a heat insulating box thereof.

[0012]

According to the present invention, there is provided a method for producing a foamed heat insulating material, comprising a first stock solution comprising an organic isocyanate and a foaming agent, a polyol, a foam stabilizer, a catalyst, a foaming agent and optionally water. In this method, a foaming agent of at least the first stock solution is made of a substance that does not react with the organic isocyanate, and this substance is dissolved in the organic isocyanate to form a rigid polyurethane foam as a heat insulating material.

[0013] In the method for producing a foamed heat insulating material according to the present invention, the foaming agent of the first undiluted solution is a substance which has a vapor pressure higher than ordinary pressure at ordinary temperature and is in a gaseous state at the undiluted solution temperature. is there.

Further, in the method for producing a foamed heat insulating material according to the present invention, the foaming agent of the second stock solution is a substance having a vapor pressure of less than normal pressure at room temperature and being in a liquid state at the stock solution temperature. is there.

In the method for producing a foamed heat insulating material according to the present invention, the foaming agent of the second undiluted solution is a substance having a vapor pressure of less than ordinary pressure at room temperature and being in a liquid state at the undiluted solution temperature, Is used by dissolving with water.

In the method for producing a foamed heat insulating material according to the present invention, the content of water to be dissolved together with the foaming agent of the second stock solution is 3 parts or less, preferably 2 parts by weight per 100 parts by weight of the polyol. Or less, more preferably 1.2 parts or less.

In the method for producing a foamed heat insulating material according to the present invention, the dissolved amount of the foaming agent in the first stock solution is 5% or less, preferably 1 to 4% based on the weight of the organic isocyanate, More preferably, the content is in the range of 2.0 to 3.5%.

In the method for producing a foamed heat insulating material according to the present invention, the foaming agent of the first undiluted solution has a carbon number of 2 to 3 hydrofluorocarbon.

Further, in the method for producing a foamed heat insulating material according to the present invention, the hydrofluorocarbon as the foaming agent of the first stock solution may be 1,1,1,2-tetrafluoroethane or 1,1,1,2,2. 2-pentafluoroethane.

In the method for producing a foamed heat insulating material according to the present invention, the boiling point of the foaming agent of the second undiluted solution is 60 ° C. or less, preferably in the range of 10 ° C. to 50 ° C.

In the method for producing a foamed heat insulating material according to the present invention, the foaming agent of the second stock solution is cyclopentane, a mixture containing cyclopentane, or a hydrofluorocarbon having 2 to 3 carbon atoms.

Further, in the method for producing a foamed heat insulating material according to the present invention, the hydrofluorocarbon as the foaming agent of the second stock solution is 1,1,1,3,3-pentafluoropropane.

[0023] In the method for producing a foamed heat insulating material according to the present invention, in the step of dissolving the foaming agent of the first undiluted solution in organic isocyanate to produce the first undiluted solution, the method comprises the steps of: This is a method in which a blowing agent is blown into an organic isocyanate in a gas state of microbubbles from the lower part to be dispersed and stirred.

In the method for producing a foamed heat insulating material according to the present invention, the foaming agent of the first undiluted solution is dispersed in the gaseous state of microbubbles into the organic isocyanate while stirring and dissolving the first undiluted solution. In this method, the blowing agent gas that has reached the upper portion of the stock solution tank without being dissolved in the organic isocyanate is sent to the organic isocyanate, and the dissolution is repeated.

In the method for producing a foamed heat insulating material according to the present invention, in the step of dissolving the foaming agent of the first stock solution in an organic isocyanate to produce the first stock solution, the foaming agent is set to a pressure higher than the saturated vapor pressure, This is a method in which a liquid state is mixed with an organic isocyanate while stirring.

In the method for producing a foamed heat insulating material according to the present invention, in the step of producing a mixture of a rigid polyurethane foam by mixing a first concentrate and a second concentrate, a first concentrate and a second concentrate are prepared. Is installed in a mixing device so that the liquid sending ports are opposed to each other, and the two stock solutions are caused to collide with each other and mixed.

Further, in the method for producing a foamed heat insulating material according to the present invention, in the step of producing a mixture of rigid polyurethane foam by impingement mixing, the foaming agent of the first stock solution is pressurized to a saturated vapor pressure or higher. This is a method in which liquid pumps are provided in pipes for feeding liquids to a first raw liquid and second raw liquid mixing apparatus, respectively, and the liquids are pumped and mixed by a liquid pump.

Furthermore, the manufacturing method of the foam insulation according to the present invention, the pressure of the liquid feed pump is at 80 kg / cm ² or more, preferably those in the range of 120~140kg / cm ^2.

The heat-insulating box according to the present invention comprises a rigid polyurethane foam produced by the above-mentioned method for producing a foamed heat-insulating material, and a box or door of a refrigerator or a similar product, and an inner box and an outer box forming these parts. The space between the boxes is filled to form a heat insulator, and this heat insulator is used.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is an explanatory view of a manufacturing process when the present invention is carried out, and FIG. 2 is a schematic view of a part of the equipment.
A detailed description will be given of a manufacturing process in the case where a heat insulator composed of a foamed heat insulating material which is a rigid polyurethane foam manufactured by this manufacturing method is used for a refrigerator which is a heat insulating box.

[First Step: Preparation Step of Isocyanate Liquid] As shown in FIG. 2, an isocyanate liquid, which is one of raw material liquids for a rigid polyurethane foam, is placed in an undiluted solution tank 2 having a measuring (weight) device 9. Using a bubble generator 6 containing isocyanate and provided at a lower portion in the stock solution tank 2 and having a tube having a large number of fine holes,
While the blowing agent supplied from the cylinder 5 is blown into the organic isocyanate in a gaseous state in the form of fine bubbles, the stirring blade 12
To dissolve the gaseous blowing agent. At this time, the gas that did not contribute to the dissolution is kept at a constant pressure, which was previously confirmed in a stable and completely dissolved state by mixing in a small amount in the container.
Is held in the stock solution tank 2 until the internal pressure of the solution reaches a predetermined value, and when the internal pressure exceeds the pressure, the relief valve 3 is released to be once collected in the collection tank 4 and reused. Then, such blowing of the gaseous foaming agent is repeated until the dissolved amount of the gaseous foaming agent reaches a predetermined amount, thereby producing an isocyanate liquid. The dissolved amount of the gaseous foaming agent is determined by the weight measured by the measuring device 9 provided in the stock solution tank 2. When the produced isocyanate liquid is sent to a mixing head 8 described later, a static mixer 10 provided in a pipe pressurized by a needle valve 11 is used.
When passing through the inside, the foaming agent is passed in a gaseous state in the form of a foam and dissolved again in the organic isocyanate, thereby increasing the dissolving efficiency.

The organic isocyanate used for the isocyanate solution thus prepared is, for example, 4,
Examples include crude 4'-diphenylmethane diisocyanate (hereinafter, referred to as polymeric MDI) or toluene diisocyanate (hereinafter, referred to as TDI) and modified products thereof, and may be those generally used in the past. Alternatively, a mixed product is used, and the mixing amount is not particularly limited.

As the gaseous blowing agent, for example, 1,1,1,2-tetrafluoroethane (hereinafter referred to as HFC-134a) or 1,1,2 containing no chlorine in the molecule.
1,2,2-pentafluoroethane (hereinafter referred to as HFC-1
24), which do not react with the organic isocyanate, have a vapor pressure not lower than normal pressure at normal temperature, are in a gaseous state at the temperature of the stock solution, and are HFC-134a for ensuring heat insulation. Is preferred. The gaseous foaming agent obtains an action of vaporizing within a very short time during mixing, and the fine bubbles obtained thereby disperse and capture a vaporized gas of a liquid foaming agent described later as a core of countless foaming. Since it promotes the action, its dissolved amount is limited to some extent. In other words, when used in a large amount as in the case of a liquid foaming agent, numerous microbubbles serving as nuclei for foaming become large on the contrary, the shape maintenance of the foam becomes unstable, and the coalescing and destruction of the bubbles accompanied by destruction are not uniform. Will occur, resulting in increased bloated foam. If a large amount of the gaseous foaming agent is further introduced, problems such as a decrease in the efficiency of the dissolving work and an increase in the tank internal pressure after the stable dissolution are caused. Therefore, the dissolved amount (content) of the gaseous blowing agent
Is 5% or less based on the weight of the organic isocyanate;
The range is preferably from 1 to 4%, and more preferably from 2.0 to 3.5%.

[First Step: Preparation Step of Premix Liquid] As shown in FIG. 2, a premix liquid as another raw material liquid for the rigid polyurethane foam was measured (weight).
A raw material tank 1 having a vessel 9a is charged with a polyol, which is a resin raw material as a main component, and is charged with a catalyst and a foam stabilizer. Next, a liquid foaming agent is added and stirred and mixed by the stirring blade 12a.
Make a premix solution. At this time, the premix liquid becomes a homogeneous liquid in which each raw material is compatible. If necessary, a foaming aid such as water or an additive such as an antistatic agent may be mixed. When the gaseous blowing agent needs to be dissolved, the dissolution is performed in the same manner as in the case of dissolving the gaseous blowing agent in the isocyanate liquid described above.

As the polyol used in the premix liquid thus prepared, all polyols usually used as urethane raw materials can be used. Among them, propylene oxide which is a polyhydric alcohol,
Ethylene oxide, ethylene glycol, glycerin, trimethylolpropane, pentaerythritol,
Sorbitol, sucrose or bisphenol A,
Examples thereof include those obtained by addition polymerization using ethylenediamine as an aliphatic amine or tolylenediamine as an aromatic amine as a starting material, and polyester polyol. The above polyol may be used as a mixture of two or more.

Examples of the liquid foaming agent include hydrocarbons such as cyclopentane, n-pentane, iso-pentane and cyclohexane, and those containing no chlorine in the molecule.
1,1,3,3-pentafluoropropane (HFC-2
45fa), 1,1,1,2,3,3-hexafluoropropane (hereinafter referred to as HFC-236ea) or 1,1,1,4,4,4-hexafluorobutane (HF
H-FCs such as C-356mffm), which have a vapor pressure higher than normal pressure at normal temperature, are liquid at the temperature of the stock solution, and cyclopentane and HFC-245fa for ensuring heat insulation. Is preferred. In this case, the liquid foaming agent is suitable for the efficiency of foaming and the filling in a foamed state because it can be easily vaporized by reaction heat. The boiling point has an upper limit for the purpose of suppressing unstable factors such as lowering the thermal conductivity. The upper limit of the boiling point of the liquid foaming agent is 60
C. or lower, preferably 50 C. or lower. Further, the lower limit of the boiling point is preferably 10 ° C. or higher at which the temperature control of the stock solution is easy.

As a foam stabilizer which is responsible for ensuring foam stability during foaming after the reaction of the organic isocyanate and the polyol when the isocyanate solution and the premix solution are mixed and for regulating the shape or size of the foam, there are known ones. Organic silicon compound-based surfactants such as F-230, F-305 and F-305 manufactured by Shin-Etsu Silicone Co., Ltd.
341 or F-348, L manufactured by Nippon Unicar Co., Ltd.
-544, L-5310, L-5320, L-5420
Or L-5720, SH manufactured by Toray Silicone Co., Ltd.
-193, SH-195, SH-200 or SRX-
253, TFA-4200 manufactured by Toshiba Silicone Co., Ltd.
Or TFA-4202 (both are trade names).

As the catalyst for adjusting the foaming or curing speed, a known amine catalyst or a metal catalyst alone or in a mixture is used. For example, tertiary amines such as trimethylamine and trimethylamine are used for the amine catalyst. Ethylenediamine, N-ethylmorpholine, trimethylaminoethylpiperazine, N, N′-dimethylaminoethylether, pentamethyldiethylenetriamine or tetramethylhexamethylenediamine, and the like. In a metal catalyst, dibutyltin dilaurate, which is an organic metal salt, Examples include tin laurate dichloride, lead octoate, cobalt naphthenate or nickel naphthenate.

As the foaming aid mixed as required, water and the like can be mentioned. This water reacts with the organic isocyanate to generate carbon dioxide as one of the foaming agents. However, since the heat conductivity is high, the heat insulating property may be reduced. Parts or less, preferably 2 parts or less, more preferably 1.2 parts or less.

[Second Step: Mixing Step of Isocyanate Solution and Premix Solution] The isocyanate solution and the premix solution prepared in each stock solution tank 2, 1 are, as shown in FIG. The liquid is sent to a mixing head 8 as a mixing device by high-pressure liquid sending pumps 7 and 7a connected to the apparatus, thereby producing a mixed liquid. Here, instead of the mixing head 8, if a material in which the undiluted solution takes a long mixing time of several seconds, such as a rotor mixer for mixing with a blade-shaped mixer, is used, the fine particles foamed by instantaneous vaporization of the foaming agent are used. The bubbles are destroyed by the shear stress applied during mixing, and the mixing ability is insufficient due to the large difference in density between the bubbles and the liquid. Therefore, in the mixing of the isocyanate liquid and the premix liquid, the two liquids collide with each other via nozzles (liquid supply ports) connected to the needle valves 11 and 11a provided in the pipes of both liquids and provided at opposed positions. Mixing, that is, it is preferable to use a mixing head 8 capable of instantaneous mixing by impingement mixing. By using this, it is possible to mix without destroying microbubbles accompanying vaporization of the gaseous blowing agent in a short time, Poor mixing due to foaming can be prevented. In addition, in order to smoothly achieve the collision mixing, a high pressure is required for the liquid discharged from the nozzle, and the pressure applied to the liquid is 80 kg / cm ² or more, and 120 to 140 k
The pressure is preferably in the range of g / cm ² , and the high-pressure liquid sending pumps 7 and 7a for generating this pressure are preferably, for example, piston cylinders or axial plunger type pumps.

[Third Step: Manufacturing Process of Molded Product (Heat Insulation Body) and Heat Insulation Box] For example, a heat insulation body used for a refrigerator is formed by a gap formed at a predetermined position by an inner box and an outer box of the refrigerator (see FIG. When a mixed liquid prepared by mixing two liquids of an isocyanate liquid and a premix liquid is injected into 3), the mixed liquid passes through a creamy state having a high fluidity in a state of being foamed to some extent by the gaseous foaming agent. In the process of foaming with the carbon dioxide gas of the liquid foaming agent and the reaction product vaporized by the heat generated by the reaction between the organic isocyanate and the polyol and water, the remaining gaps are filled without gaps, forming a heat insulator. You. The time required for filling is 15 to 30 seconds, and the shape of the heat insulator is maintained by the subsequent resinification. And the refrigerator which is a heat insulation box is formed using this heat insulation.

As described above, by mixing a premix liquid containing a polyol as a main component and an isocyanate liquid comprising a gaseous foaming agent having poor compatibility and an organic isocyanate while maintaining the compatibility state in the isocyanate liquid, On the other hand, in the premix solution, the amount of the foaming agent which causes the emulsion or separation exceeds the dissolution limit, and a uniform and stable state due to the improvement in compatibility can be secured.

Further, when a liquid foaming agent and a gaseous foaming agent are simply used together in a premix solution, a method disclosed in JP-A-4-35654 is used.
As a result, only a large cell can be obtained as in the foam according to the invention disclosed in JP-A-5-98061, or the thermal conductivity of gas increases as in the foam according to the invention disclosed in JP-A-5-98061. Therefore, it is not necessarily effective for improving the heat insulating property of the obtained foam, and may be lowered. Therefore, when a gaseous blowing agent such as HFC-134a is mixed with an isocyanate solution, the progress of decomposition is slower because water or amines are not present than when mixed with a premix solution. The storage stability is also improved.

Further, when the two liquids are mixed using a high-pressure foaming machine (mixing device) including a mixing head 8 and liquid feed pumps 7 and 7a, the gaseous foaming agent having poor compatibility with the premix liquid is vaporized. Promotes the generation of fine air bubbles, thereby improving the filling property of the foam accompanying the miniaturization of cells and the improvement of the expansion rate of foaming, and the heat insulating property can be achieved.

Accordingly, an isocyanate solution comprising an organic isocyanate and a gaseous foaming agent (HFC-134a) dissolved in a dissolved amount of 5% or less with respect to the organic isocyanate, a polyol, a foam stabilizer, a catalyst, and Is a mixture of water and a premix liquid mixed with a liquid foaming agent (cyclopentane and / or HFC245-fa) having a boiling point in the range of 10 ° C to 50 ° C. It is a heat-insulating box body because it can secure a fine cell structure as a rigid polyurethane foam that is filled in the gap between the inner box and the outer box of the refrigerator and constitutes a heat insulator and can improve heat insulation properties. It turns out that it is suitable as a rigid polyurethane foam used for refrigerators. The effects of this rigid polyurethane foam will be specifically described below using examples.

[0046]

【Example】

[Examples 1 to 3] In each of the examples and comparative examples, a raw material system was selected so that the properties of the stock solution were transparent, and foaming was performed using a stock solution obtained by dissolving a gaseous foaming agent in organic isocyanate. Of the rigid polyurethane foam obtained by the method described above was examined for its fineness and its influence on the heat insulation. Note that cyclopentane was selected as the liquid blowing agent, and HFC-134a was selected as the gaseous blowing agent.

First, raw materials were formulated as shown in Table 1, and a panel of a rigid polyurethane foam as a sample was prepared by the following methods (1) to (4).
Form 3 (1) a polyol A, a foam stabilizer,
A catalyst and a liquid blowing agent are mixed to prepare a premix liquid (see FIGS. 1 and 2). (2) A gaseous blowing agent is blown into an organic isocyanate while stirring to dissolve it, thereby preparing an isocyanate liquid (see FIGS. 1 and 2). (3) The premix liquid and the isocyanate liquid were mixed at a predetermined mixing ratio using a high-pressure foaming machine to prepare a mixed liquid, and the mixed liquid was heated to 40 ° C.
A foam is filled in an aluminum mold (width) × 400 (length) × 45 (thickness) mm and overflows about 100 mm from the upper part of the aluminum mold (see FIGS. 1 and 2). (4) A rigid polyurethane foam panel formed and sealed in an aluminum mold so that the weight of the filled foam is increased by 15% of the weight after removing the overflowed portion, and a demolding time of 6 minutes is used as a sample. (See FIG. 1).

[0048]

[Table 1]

In Examples 1 to 3, the dissolved amount of the gaseous blowing agent HFC-134a dissolved in the organic isocyanate was adjusted to 1.5 parts by weight per 100 parts by weight of the polyol A.
Parts, 3.0 parts, and 5.0 parts, and Comparative Example 1
Uses only the liquid blowing agent cyclopentane in the premix liquid and uses the gaseous blowing agent HFC-134a in the isocyanate liquid.
In Comparative Example 2, the liquid blowing agent cyclopentane and the gaseous blowing agent HFC-13 were added to the premix liquid.
In the case of using both of 4a and Comparative Example 3, the amount of the gaseous blowing agent HFC-134a dissolved in the isocyanate liquid exceeds 5% based on the weight of the organic isocyanate.

The organic isocyanate is polymethylene polyphenyl polyisocyanate (MDI), and the polyol A is tolylenediamine to which ethylene oxide and propylene oxide are added, and the average hydroxyl value is 420 mgK.
OH / g aromatic amine-based polyether polyol, the catalyst is a mixture of TMHDA (tetramethylhexamethylenediamine) and N-methylmorpholine in a ratio of 8: 2, and the foam stabilizer is Nippon Unicar Co., Ltd. L-53
20 (trade name) were used respectively.

In each of the samples thus formed, the core density of the foam (10 m on both sides of the sample panel)
m), compressive strength, low-temperature dimensional stability, thermal conductivity, cell size and HF
The vapor pressure of C-134a was measured. The details of each measurement are as follows, and the measurement results are shown in Table 2. Core density: The apparent volume calculated from the outer dimensions of the caliper and the apparent density calculated from the weight. Compressive strength: 10% at a compression speed of 10 mm / min
Strength when strained. Low temperature dimensional stability: dimensional change rate before and after standing at −30 ° C. for 48 hours. Thermal conductivity: Anacon-model 88 applying the flat plate comparison method
(Amco). Cell size: Average value for the maximum distance in the thickness direction. Vapor pressure: The pressure of the stock solution tank after leaving the stock solution tank at 20 ° C for 24 hours.

[0052]

[Table 2]

As is clear from the results in Table 2, Comparative Example 1 using only the liquid blowing agent cyclopentane and Comparative Example 2 using the liquid blowing agent cyclopentane and the gaseous blowing agent HFC-134a in combination were: Its thermal conductivity is 0.0173
There is almost no difference between kcal / mh ° C and 0.0172 kcal / mh ° C, and the cell size is 250 μm and 21 μm.
Since no significant difference was observed at 0 μm, even when the gaseous foaming agent HFC-134a was mixed with the polyol A, no effect on the fineness of the gaseous foaming agent was recognized. On the other hand, Examples 1 to 3 in which the gaseous blowing agent HFC-134a is dissolved in the organic isocyanate are:
In each case, the thermal conductivity and the cell size show small values. For example, in Example 2, the cell size was 150 μm.
m and a thermal conductivity of 0.016
As low as 8 kcal / mh ° C., an improvement in heat insulation is observed. Further, the vapor pressure of Example 2 was 0.4 times lower than that of Comparative Example 2.
kg / cm ² lower value and the gaseous blowing agent HFC-13
This suggests that the lack of quality stability due to the scattering of 4a can also be suppressed. Furthermore, in terms of low-temperature dimensional stability, in Comparative Example 1 and the like, a shrinkage behavior requiring a high density is obtained at the stage of actual use, whereas in Examples 1 to 3, the density of the material is almost unchanged. It shows possible good values.

In Comparative Example 3 in which the dissolved amount of the gaseous blowing agent HFC-134a exceeds 5%, the vapor pressure is considered to be dangerous in normal handling, and is regulated by the High Pressure Gas Control Law. 3.6 kg / c of 0 kg / cm ² or more
indicates the m ^2, also, since the expansion ratio immediately after foaming is strong mixing of the liquid mixture is greater, after being concerned that there is a possibility that interfere with fluidity, the resulting foam gaseous There are many voids due to bumping of the foaming agent HFC-134a, and this is an unsuitable situation in both production and quality. On the other hand, in Examples 1 to 3, the rise in vapor pressure was very small, and 2.0 kg / cm ² which can be handled normally.
It was below.

Therefore, as in Examples 1 to 3, the liquid blowing agent cyclopentane is mixed with the polyol A, and the gaseous blowing agent HFC-134a is mixed with the organic isocyanate so that the dissolved amount is 5% or less. It can be seen that the dissolved one is suitable for a rigid polyurethane foam.

[Examples 4 to 6] In each of Examples and Comparative Examples, the raw material system was selected so that the properties of the stock solution were essentially cloudy, and the gaseous blowing agent was dissolved in the organic isocyanate. The effect of reducing the amount of the foaming agent in the premix liquid to improve the properties of the transparent and homogeneous stock solution was confirmed, and the effect of improving the heat insulating property accompanying the miniaturization of cells was examined. Note that cyclopentane was used in combination with water as a liquid blowing agent, and HFC-134 was used as a gaseous blowing agent.
a was selected.

First, raw materials were formulated as shown in Table 3, and a panel of a rigid polyurethane foam to be a sample was prepared by the following methods (1) to (4), Examples 4 to 6 and Comparative Examples 4 to
6 is formed. (1) Polyol B, water, a foam stabilizer, a catalyst, and a liquid foaming agent are mixed based on a predetermined compounding ratio to prepare a premix liquid. (2) In the same manner as in Examples 1 to 3, the gaseous blowing agent is blown into the organic isocyanate while stirring to dissolve it, thereby preparing an isocyanate liquid. (3) For each of the premix solution and the isocyanate solution, the internal pressure of each stock solution tank is 0.2 kg / cm
After pressurizing with ² nitrogen gas, respectively, using a high pressure foaming machine to prepare a mixed solution was mixed at a predetermined mixing ratio, heated 300 (width) in the mixture 40 ° C. × 400 (length ) × 4
A foam is filled in an aluminum mold having a thickness of 5 (thickness) and overflows about 100 mm from the upper part of the aluminum mold. (4) A rigid polyurethane foam panel formed and sealed in an aluminum mold so that the weight of the filled foam is increased by 15% of the weight after removing the overflowed portion, and a demolding time of 6 minutes is used as a sample. I do.

[0058]

[Table 3]

In Examples 4 to 6, the dissolved amount of the gaseous blowing agent HFC-134a dissolved in the organic isocyanate was 2.5 parts per 100 parts by weight of the polyol B.
Part, 4.5 parts, and 6.0 parts.
Is a premix liquid in which both a liquid blowing agent cyclopentane and a gaseous blowing agent HFC-134a are used in combination, and Comparative Examples 5 and 6 are gaseous blowing agents H dissolved in an isocyanate liquid.
The dissolved amount of FC-134a exceeds 5% based on the weight of the organic isocyanate.

The organic isocyanate was polymethylene polyphenyl polyisocyanate (MDI), and the polyol B was a mixture of sucrose and glycerin in a ratio of 8: 2 to which propylene glycol was added, and the average hydroxyl value was 390 mgKOH / g. Polyether polyol,
The catalyst was a mixture of PMDETA (pentamethyldiethylenetriamine) and dibutyltin dilaurate in a ratio of 95: 5, and the foam stabilizer was L-5 manufactured by Nippon Unicar Co., Ltd.
320 (trade name) were used respectively.

In each of the samples thus formed, the core density of the foam (10 m on both sides of the sample panel)
m), compressive strength, dimensional stability at low temperature, thermal conductivity, cell size, and H
The vapor pressure of FC-134a was measured according to the measurement contents described in Examples 1 to 3. Further, the appearance properties of the premix solution were visually observed to examine its homogeneity, particularly turbidity. Table 4 shows the measurement results and the observation results.

[0062]

[Table 4]

As is clear from the results in Table 4, Comparative Example 4 in which the liquid blowing agent cyclopentane and the gaseous blowing agent HFC-134a were used in combination had a thermal conductivity of 0.0178 kcal.
/ Mh ° C. and the cell size is as large as 190 μm. On the other hand, in Examples 4 to 6, in which the gaseous blowing agent HFC-134a was dissolved in the organic isocyanate in the range of 1.9 to 4.8%, the thermal conductivity and the cell size were all low. It shows a small value. Also,
In Comparative Examples 5 and 6 in which the dissolved amount of the gaseous blowing agent HFC-134a exceeds 5%, the thermal conductivity and the cell size show small values, but the vapor pressure is 2.0 k.
It is a high value exceeding g / cm ² . Further, in Comparative Example 4 in which the liquid foaming agent cyclopentane and gaseous blowing agent HFC-134a having poor solubility in the premix liquid are present in a large amount, and in Examples 4 to 6 and Comparative Examples 5 and 6 in which the present is not present in a large amount, The appearance properties of the premix liquid differ greatly. That is, Comparative Example 4 is in a strong emulsion state and is in a separated state, but Examples 4 to 6 and Comparative Examples 5 and 6 do not show a separated state, and the dissolved amount of the gaseous blowing agent HFC-134a is large. The color is transparent without turbidity.

Here, from the viewpoint of the appearance properties of the premix solution, a cell in which the dissolved amount of the gaseous foaming agent HFC-134a is increased can make the cell finer, but from the viewpoint of the vapor pressure, the dissolved amount can be reduced. Is preferably 5% or less, and among them, Example 6 has a specified pressure of 2.0 kg / cm ^2.
, The dissolved amount is preferably in the range of 2.0 to 3.6% as in Examples 4 and 5.

Therefore, the gaseous blowing agent HFC-134
a is dissolved in an organic isocyanate so that the dissolved amount thereof is 5% or less, preferably in the range of 1 to 4%, and more preferably in the range of 2.0 to 3.5%. It can be miniaturized, thereby lowering the thermal conductivity and improving the heat insulation,
It can be seen that the storage stability can be improved, and Examples 4 to 6, particularly those of Examples 4 and 5, are suitable for rigid polyurethane foam.

[Examples 7 and 8] Here, HFC-245fa which is a hydrofluorocarbon as a liquid foaming agent is used.
And the use of water in combination with it so that the stock solution properties of the premix solution become essentially cloudy, thereby improving the homogeneity and stability of the stock solution, miniaturizing the cell size, and concomitantly improving the heat insulation. Was examined.

First, raw materials were formulated as shown in Table 5, and a panel of a rigid polyurethane foam as a sample was prepared by the following methods (1) to (4). Examples 7 and 8 and Comparative Examples 7 to
9 is formed. (1) A premix liquid is prepared by mixing polyol C, water, a foam stabilizer, a catalyst, and a liquid foaming agent based on a predetermined compounding ratio. (2) In the same manner as in Examples 1 to 3, the gaseous blowing agent is blown into the organic isocyanate while stirring to dissolve it, thereby preparing an isocyanate liquid. (3) The temperature of both the premix solution and the isocyanate solution was adjusted to 17 ° C., and the internal pressure of each stock solution tank was set to 0.2 k.
After pressurizing with nitrogen gas of g / cm ² , each was mixed at a predetermined compounding ratio using a high-pressure foaming machine to prepare a mixed solution, and the mixed solution was heated to 40 ° C. and 300 (width) × 400. A foam is filled in an aluminum mold (length) × 45 (thickness) mm and overflows about 100 mm from the upper part of the aluminum mold. (4) A rigid polyurethane foam panel formed and sealed in an aluminum mold so that the weight of the filled foam is increased by 15% of the weight after removing the overflowed portion, and a demolding time of 6 minutes is used as a sample. I do.

[0068]

[Table 5]

In Examples 7 and 8, the dissolved amount of the gaseous blowing agent HFC-134a dissolved in the organic isocyanate was 3.5 parts by weight per 100 parts by weight of the polyol A.
Comparative Example 7 used only the liquid foaming agent HFC-245fa in the premix solution and did not dissolve the gaseous foaming agent HFC-134a in the isocyanate solution. Comparative Example 8 In the premix solution, both the liquid foaming agent HFC-245fa and the gaseous foaming agent HFC-134a were used in combination. In Comparative Example 9, the dissolved amount of the gaseous foaming agent HFC-134a dissolved in the isocyanate liquid was calculated based on the weight of the organic isocyanate. On the other hand, it exceeds 5%.

The organic isocyanate is polymethylene polyphenyl polyisocyanate (MDI), the polyol C is a mixed polyether polyol having an average hydroxyl value of 420 mgKOH / g, and is an aromatic amine-based polyamine obtained by adding propylene oxide to tolylenediamine. Shoe-cloth-based polyol with propylene oxide added to ether polyol and shoe-close, catalyst is PMD
ETA (pentamethyldiethylenetriamine) and foam stabilizer are L-5320 (trade name) manufactured by Nippon Unicar Co., Ltd.
Was used for each.

In each of the samples thus formed, the core density of the foam (10 m on both sides of the sample panel)
m), compressive strength, dimensional stability at low temperature, thermal conductivity, cell size, and H
The vapor pressure of FC-134a was measured by the measurement contents described in Examples 1 to 3, and the homogeneity, particularly the turbidity, of the foam was examined by visual observation. Table 6 shows the measurement results and the observation results.

[0072]

[Table 6]

As is clear from the results in Table 6, even when HFC-245fa, which is a hydrofluorocarbon, was used as the liquid foaming agent, Example 7 was compared with Comparative Examples 7 and 8 in the same manner as in the case of hydrocarbon cyclopentane. , 8 have low thermal conductivity and small cell size. In Comparative Example 9 in which the dissolved amount of the gaseous foaming agent HFC-134a exceeds 5%, the vapor pressure shows a high value exceeding the specified 2.0 kg / cm ^2, and the foaming of the mixed solution is strong. Since the foaming ratio immediately after is large, there is a possibility that the fluidity may be impaired, and the obtained foam may contain a gaseous foaming agent HFC-
Although there are many voids due to bumping of 134a, it is unsuitable for both production and quality. However, in Examples 7 and 8, the rise in vapor pressure is very small and 2.0 kg / cm ² or less, which can be handled normally. The appearance of the obtained foam is good, and it is suitable in both production and quality.

Therefore, as in Examples 7 and 8, a liquid foaming agent HFC-245fa is mixed with polyol C,
HFC-13 gaseous blowing agent for organic polyisocyanates
When 4a is dissolved so that its dissolved amount is 5% or less,
It can be seen that a rigid polyurethane foam having the effect of miniaturizing the cells and improving the heat insulation can be obtained.

[Examples 9 to 11] Here, cyclopentane or HFC-245fa was selected as a liquid foaming agent, and a premix liquid using water in combination with the mixture, and an isocyanate in which HFC-134a was selected as a gaseous foaming agent. The mixture with the liquid is filled in the gap between the inner box and the outer box of the refrigerator to form a heat insulator, and the strength when this heat insulator is applied to the refrigerator,
The effects on the improvement of filling property and reduction of power consumption were investigated.

First, raw materials were formulated as shown in Table 7, and the following heat-insulating bodies of a refrigerator made of a rigid polyurethane foam were prepared by the following methods (1) to (5), Examples 9 to 11 and Comparative Examples 10-12 are formed. (1) Any one of polyols B, C, and D, water, a foam stabilizer, a catalyst, and a liquid foaming agent (either cyclopentane or HFC-245fa) are mixed based on a predetermined mixing ratio, and premixed Make a liquid. (2) A gaseous blowing agent is blown into the organic isocyanate while stirring to dissolve it, thereby preparing an isocyanate liquid. (3) The premix liquid and the isocyanate liquid are mixed using a high-pressure foaming machine to prepare a mixed liquid. (4) The mixed solution is injected, foamed, and filled into the gap between the inner box made of ABS resin and the outer box made of pre-coated steel sheet, which is the box part of the refrigerator placed on the jig preheated to 45 ° C. (5) The filled foam is allowed to stand for 6 minutes, and then a heat insulator composed of the rigid polyurethane foam is assembled to form a refrigerator as a heat insulating box. Then, a heat insulator taken from the refrigerator whose power consumption was measured is used as a sample. The refrigerator used here is, for example, 400 L
It is a (liter) class refrigerator.

[0077]

[Table 7]

In Examples 9, 10, and 11, the polyols were changed to B, C, and D. In Example 10, the liquid blowing agent was changed to HFC-245fa, and the dissolved amount of the gaseous blowing agent HFC-134a was changed. Was higher than Examples 9 and 11, and Comparative Examples 10 to 12
C and D and vice versa, in which the gaseous foaming agent HFC-134a was not dissolved in the isocyanate liquid, and the premix liquid used was either the liquid foaming agent cyclopentane or HFC-245fa and water in combination.

The organic isocyanate was polymethylene polyphenyl polyisocyanate (MDI), and the polyol B was a mixture of sucrose and glycerin in a ratio of 8: 2 to which propylene glycol was added, and the average hydroxyl value was 390 mgKOH / g. Polyether polyol,
Polyol C is a mixed polyether polyol having an average hydroxyl value of 420 mgKOH / g, and is an aromatic amine-based polyether polyol obtained by adding propylene oxide to tolylenediamine, a shoe-closed polyol obtained by adding propylene oxide to shoe-closed, and a polyol. D is a mixture of sorbitol and ethylenediamine at a ratio of 8: 2 to which ethylene oxide and propylene oxide are added, and the average hydroxyl value is 380 mg KO.
H / g mixed polyether polyol, catalyst is PMDE
TA (pentamethyldiethylenetriamine) and L-5320 (trade name) manufactured by Nippon Unicar Co., Ltd.
Each was used.

Then, in the refrigerator using the heat insulator of each sample thus formed, the power consumption was measured, and then each refrigerator was disassembled and each sample collected from the position of X shown in FIG. In the (insulation), the core density of the foam (the density which is the physical property of the core obtained by removing both sides of the sample panel by 10 mm), the compressive strength, the dimensional stability at low temperature, the thermal conductivity, and the cell size were measured in Examples. In addition to measuring the contents described in 1 to 3 above, the appearance properties of the premix solution were examined by visual observation for homogeneity, particularly turbidity, and the appearance properties of the foam. Table 8 shows the measurement results and the observation results. The measurement of the power consumption is based on JIS
The measurement was performed in accordance with the power consumption measurement and the B method in -9607, and the measurement error between the samples was eliminated by replacing the door and the compressor.

[0081]

[Table 8]

As is clear from the results shown in Table 8, the refrigerators using the heat insulators of Examples 9 to 11 using the isocyanate liquid in which the gaseous blowing agent HFC-134a was dissolved in the organic isocyanate were gaseous. Blowing agent HFC-134
Compared with the refrigerators using the heat insulators of Comparative Examples 10 to 12 not using a, the power consumption shows a low value as a whole, and the heat conductivity which is a factor of this reduction also shows a small value. And improved heat insulation. The cell size also shows a small value, indicating that the gaseous blowing agent HFC-134
It can be seen that by dissolving a in the organic isocyanate, the cell is miniaturized.

Example 9 also shows the appearance of the foam.
~ 11, the discoloration area is a trace of the broken cells of the foam surface in the back part and the bottom part corresponding to the latter half of the filling, it can be seen that compared to Comparative Examples 10-12,
It can be confirmed that the trace of the weld at the bottom is also weak.
This suggests that the rigid polyurethane foams constituting the heat insulators of Examples 9 to 11 have excellent fluidity and can prevent the occurrence of poor filling or suppress the required filling amount.

Therefore, the hydrocarbon cyclopentane and the hydrofluorocarbon HFC-24
When 5fa is used as a liquid foaming agent, by using HFC-134a, which is a gaseous foaming agent, dissolved in an organic polyisocyanate, the heat insulating property based on the miniaturization of cells is significantly improved. It can be seen that when used as a heat insulator for a refrigerator, it has an excellent effect in improving the power consumption of the refrigerator.

Further, when the liquid foaming agent alone or the gaseous foaming agent mixed in the premix liquid side with those of Comparative Examples 10 to 12 were used in a refrigerator, the shrinkage at a low temperature may hinder the appearance of the refrigerator. Remarkably occurred. On the other hand, when the gaseous blowing agent of Examples 9 to 11 in which the dissolved amount is 5% or less in the isocyanate liquid is used for a refrigerator, the dimensional stability is improved and the appearance is improved. It was confirmed that there was no fear of causing trouble, the storage stability of the premix solution and the heat insulation performance due to the remarkable miniaturization of the cell size were improved, and the effect of reducing the power consumption of the refrigerator was confirmed. Therefore, it can be seen that those of Examples 9 to 11 are suitable for the rigid polyurethane foam constituting the heat insulator of the refrigerator.

In the above-described embodiments and examples, the case where the heat insulator is used as a heat insulator for a refrigerator is shown. However, the present invention is not limited to this. For example, a heat insulator for a refrigerator car, a prefabricated refrigerator, or a heat insulator for a showcase. May be used. In this case, the same effect can be obtained.

[0087]

As described above, the method for producing a foamed heat insulating material according to the present invention comprises a first stock solution comprising an organic isocyanate and a foaming agent, a polyol, a foam stabilizer, a catalyst, a foaming agent and optionally water. The method comprises a second undiluted solution, at least a foaming agent of the first undiluted solution is a substance that does not react with the organic isocyanate, and this substance is dissolved in the organic isocyanate to form a rigid polyurethane foam as a heat insulating material. In the stock solution 2, the amount of the foaming agent can be reduced so that its properties do not cause emulsion or separation, and a heat insulating material having good storage stability can be obtained.

In the method for producing a foamed heat insulating material according to the present invention, the foaming agent of the first stock solution is a substance which has a vapor pressure at room temperature or higher and a gaseous state at the stock solution temperature. It is possible to easily obtain fine bubbles as nuclei for foaming, promote the formation thereof, further miniaturize the cells, and obtain a heat insulating material capable of improving heat insulating properties.

Further, in the method for producing a foamed heat insulating material according to the present invention, the foaming agent of the second stock solution may be a substance having a vapor pressure of less than normal pressure at room temperature and being in a liquid state at the stock solution temperature, or Since this method is used by dissolving this substance together with water, the flowability of air bubbles can be improved, and a heat insulating material having a good filling property in a mold can be obtained.

In the method for producing a foamed heat insulating material according to the present invention, the content of water dissolved together with the foaming agent of the second stock solution is 3 parts or less, preferably 2 parts by weight per 100 parts by weight of the polyol. Since the content is set to not more than 1.2 parts, and more preferably not more than 1.2 parts, it is possible to suppress a decrease in heat insulating property due to water.

In the method for producing a foamed heat insulating material according to the present invention, the dissolved amount of the foaming agent in the first stock solution is 5% or less, preferably 1 to 4%, based on the weight of the organic isocyanate; More preferably, the content is in the range of 2.0 to 3.5%, so that the expansion of the foam can be improved without uniformity of the shape of the cells and without increasing the viscosity, and the filling into the mold can be easily performed. A heat insulating material that can form a suitable core that can be obtained can be obtained.

Further, in the method for producing a foamed heat insulating material according to the present invention, the foaming agent of the first stock solution is a hydrofluorocarbon having 2 to 3 carbon atoms, and the hydrofluorocarbon is 1,1,1,2- Tetrafluoroethane or 1,
Since it is 1,1,2,2-pentafluoroethane, an effect of vaporizing within an extremely short time upon mixing can be obtained, and fine bubbles obtained by this action can be used as nuclei of countless foams to form the second stock solution. The effect of dispersing and trapping the vaporized gas of the foaming agent can be promoted, and the cells can be made finer to obtain a heat insulating material having excellent heat insulating properties.

In the method for producing a foamed heat insulating material according to the present invention, since the boiling point of the foaming agent of the second undiluted solution is 60 ° C. or less, preferably in the range of 10 ° C. to 50 ° C., the use temperature is lowered. Due to the liquefaction, the ratio of the foaming agent present in the cells to the gas can be prevented from decreasing, and the decrease in the thermal conductivity can be suppressed.

Further, in the method for producing a foamed heat insulating material according to the present invention, the foaming agent of the second stock solution is cyclopentane, a mixture containing cyclopentane, or a hydrofluorocarbon having 2 to 3 carbon atoms. ,
Since it is 1,1,1,3,3-pentafluoropropane, it can be easily vaporized by the heat of reaction and is suitable for foaming efficiency and filling in a foamed state, and also causes deterioration of thermal conductivity. It is possible to obtain a heat insulating material capable of suppressing unstable elements and improving heat insulating properties.

In the method for producing a foamed heat insulating material according to the present invention, in the step of dissolving the foaming agent of the first undiluted solution in organic isocyanate to produce the first undiluted solution, the method comprises the steps of: Since it is a method in which the blowing agent is blown into the organic isocyanate in a gas state of microbubbles and dispersed while stirring from the lower portion, the blowing agent of the first stock solution can be easily dissolved in the organic isocyanate,
The operation of preparing the first undiluted solution can be facilitated.

Further, the method of manufacturing a foamed heat insulating material according to the present invention is a method of manufacturing a first undiluted solution in which a foaming agent of a first undiluted solution is blown into an organic isocyanate in a gas state of microbubbles, dispersed, stirred and dissolved. In this method, the gas of the foaming agent that has reached the upper portion of the stock solution tank without being dissolved in the organic isocyanate is sent to the organic isocyanate, and the dissolution is repeated. In addition, it is possible to obtain an economical method of manufacturing a heat insulating material with less loss of a foaming agent.

In the method for producing a foamed heat insulating material according to the present invention, in the step of dissolving the foaming agent of the first undiluted solution in an organic isocyanate to produce the first undiluted solution, the blowing agent is set to a pressure higher than the saturated vapor pressure, Since it is a method of mixing and stirring the liquid in the organic isocyanate with the organic isocyanate, the foaming agent of the first stock solution can be efficiently dissolved in the organic isocyanate, and the workability of preparing the first stock solution can be improved. it can.

In the method for producing a foamed heat insulating material according to the present invention, in the step of producing a mixture of a rigid polyurethane foam by mixing the first concentrate and the second concentrate, the first concentrate and the second concentrate are prepared. Is a method in which a liquid feed port of the first raw liquid is placed in a mixing device so as to face the raw liquid, and the two raw liquids are caused to collide with each other. Is provided in the pipes for sending the first undiluted solution and the second undiluted solution to the mixing device, respectively, and the liquid is pumped and mixed by the liquid sending pump. In this method, the first stock solution and the second stock solution can be mixed without destroying the microbubbles, and the mixing failure due to foaming can be prevented.

[0099] The manufacturing method of foam insulation according to the present invention, the pressure of the liquid feed pump is at 80 kg / cm ² or more, so preferably has a range of 120~140kg / cm ^2, gaseous foam It is possible to prevent the destruction of microbubbles and poor mixing due to the vaporization of the agent within a short time, and it is possible to perform good mixing.

The heat-insulating box according to the present invention comprises a rigid polyurethane foam produced by the above-mentioned method for producing a foamed heat-insulating material, and a box or door made of a refrigerator or a similar product, and an inner box and an outer box forming these parts. Since a heat insulator is formed by filling the gaps of the box and using the heat insulator, a heat insulating box having excellent heat insulating properties can be obtained. This makes it possible to obtain an economical heat-insulating box that can reduce the amount of power consumption while protecting the global environment.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a manufacturing process when the present invention is carried out.

FIG. 2 is a schematic diagram of a part of equipment for implementing the present invention.

FIG. 3 is a schematic diagram showing a sampling position in dismantling a prototype refrigerator.

[Explanation of symbols]

1, 2 stock solution tank, 6 bubble generator, 7, 7a liquid sending pump, 8 mixing head, 9, 9a measuring device.

Claims (18)

[Claims] 1. A first undiluted solution comprising an organic isocyanate and a foaming agent, and a second undiluted solution containing a polyol, a foam stabilizer, a catalyst, a blowing agent and optionally water, and at least foaming of the first undiluted solution. A method for producing a foamed heat insulating material, characterized in that the agent is a substance that does not react with an organic isocyanate, and the substance is dissolved in the organic isocyanate to form a rigid polyurethane foam as a heat insulating material. 2. The foam insulating material according to claim 1, wherein the foaming agent of the first stock solution is a substance having a vapor pressure at normal temperature or higher and a gaseous state at the stock solution temperature. Production method. 3. The foam insulation according to claim 1, wherein the foaming agent of the second stock solution is a substance having a vapor pressure of less than normal pressure at room temperature and being in a liquid state at the stock solution temperature. The method of manufacturing the material. 4. The method according to claim 1, wherein the foaming agent of the second undiluted solution has a vapor pressure of less than ordinary pressure at normal temperature and is in a liquid state at undiluted solution temperature, and the substance is dissolved and used together with water. The method for producing a foamed heat insulating material according to claim 1. 5. The content of water to be dissolved together with the foaming agent of the second stock solution is 3 parts or less, preferably 2 parts or less, more preferably 1.2 parts, per 100 parts by weight of the polyol. 5. The method according to claim 4, wherein
A method for producing the foam insulation material according to the above. 6. The dissolved amount of the foaming agent in the first undiluted solution is 5% or less, preferably 1 to 4%, more preferably 2.0%, based on the weight of the organic isocyanate.
2. The method according to claim 1, wherein the value is within a range of about 3.5%.
6. The method for producing a foamed heat insulating material according to 2, 3, 4, or 5. 7. The foaming agent of the first undiluted solution has a carbon number of 2-3.
The method for producing a foamed heat insulating material according to claim 1, 2, 3, 4, 5, or 6, wherein 8. The hydrofluorocarbon as a foaming agent of the first stock solution is 1,1,1,2-tetrafluoroethane or 1,1,1,2,2-pentafluoroethane. A method for producing the foamed heat insulating material according to claim 7. 9. The method according to claim 1, wherein the boiling point of the foaming agent of the second undiluted solution is 60 ° C. or less, preferably in the range of 10 ° C. to 50 ° C. , 6, 7 or 8. 10. The blowing agent of the second undiluted solution is cyclopentane, a mixture containing cyclopentane or a mixture containing 2 to 3 carbon atoms.
The method for producing a foamed heat insulating material according to claim 1, 2, 3, 4, 5, 6, 7, 8, or 9. 11. The method according to claim 10, wherein the hydrofluorocarbon as the foaming agent of the second stock solution is 1,1,1,3,3-pentafluoropropane. 12. In a step of dissolving a foaming agent of the first stock solution in the organic isocyanate to produce a first stock solution, the foaming agent is finely bubbled from a lower portion in a stock solution tank containing the organic isocyanate. And stirring while blowing and dispersing the organic isocyanate in the gaseous state of (1), (2), (3), (4), (5), (6) and (7).
12. The method for producing a foamed heat insulating material according to 8, 9, 10 or 11. 13. In the step of producing the first undiluted solution, the blowing agent of the first undiluted solution is blown into the organic isocyanate in a gaseous state in the form of microbubbles, and is stirred and dissolved while being dispersed. The method according to claim 12, wherein the gas of the foaming agent that has reached the upper portion in the stock solution tank is sent to the organic isocyanate, and the dissolution is repeated. 14. A step of dissolving the foaming agent of the first stock solution in the organic isocyanate to produce a first stock solution, the foaming agent being at a pressure higher than the saturated vapor pressure, and stirring the organic isocyanate in a liquid state. And mixing while mixing.
12. The method for producing a foamed heat insulating material according to 10 or 11. 15. In the step of producing a mixed solution of a rigid polyurethane foam by mixing the first undiluted solution and the second undiluted solution, the liquid feed ports of the first undiluted solution and the second undiluted solution are opposed to each other. 4. The method according to claim 1, wherein the two undiluted liquids are set in a mixing device and mixed by collision.
The method for producing a foamed heat insulating material according to 6, 7, 8, 9, 10, 11, 12, 13, or 14. 16. In the step of producing a mixture of a rigid polyurethane foam by impingement mixing, the liquid sending pump for pressurizing the foaming agent of the first stock solution to a saturated vapor pressure or higher is used for the first stock solution and the second stock solution. 16. The method for producing a foamed heat insulating material according to claim 15, wherein said stock solution is provided in a pipe for sending each of said stock solutions to said mixing device, and is subjected to collision mixing by said solution sending pump. 17. The pressure of the liquid sending pump is 80 kg / cm.
² or more, preferably 120 to 140 kg / cm ²
17. The method for producing a foamed heat insulating material according to claim 16, wherein: 18. A rigid polyurethane foam produced by the production method according to any one of claims 1 to 17, comprising a box of a refrigerator or a similar product, a door, or an inner box forming these parts. A heat-insulating box, wherein the heat-insulating body is formed by filling a gap between outer boxes to form a heat-insulating body.