JP2010138239A - Method for producing foamed polyurethane, and heat-insulating box - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a high-quality foamed polyurethane. <P>SOLUTION: A third raw material 105 containing a foaming agent 106 whose boiling point is 0°C or less at a nearly atmospheric pressure is mixed with a first raw material 101 at upstream of a mixing head 103. After mixing, the first raw material 101 and the third raw material 105 are mixed with a second raw material 102 at the mixing head 103 and discharged out of the system. That is, the third raw material 105 comes to contain the foaming agent 106 in a path different from those of the main first raw material 101 and second raw material 102, thereby securing enough mixing time to enable uniform mixing. Thus, the high-quality foamed polyurethane is produced as an appropriate amount of the foaming agent 106 is contained in the raw materials of the foamed polyurethane. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polyurethane foam using carbon dioxide gas as a foaming agent and a heat insulating box using the polyurethane.

  In recent years, from the viewpoint of protecting the global environment, there is an increasing social demand for technological development that efficiently uses thermal energy. Manufacturers that manufacture refrigeration equipment and thermal equipment are focusing on the development of heat insulation technology in addition to energy-saving design of various parts and equipment as a whole.

  A typical electric refrigerator-freezer is a typical refrigerator-freezer. Technological innovation in this field is remarkable, and the power consumption of electric refrigerator-freezers with the same capacity as past products has been reduced to a fraction of a fraction.

  In addition, with the changing lifestyles of consumers, there is a strong demand to increase the capacity without expanding the installation area. For this reason, recent electric refrigerator-freezers meet demands by reducing the wall thickness by improving heat insulation performance, improving the performance of each functional component, or optimizing the layout design. As an example of wall thinning, in addition to polyurethane foam that has been widely used as a heat insulating material, the use of a vacuum heat insulating material that has superior heat insulating performance has been advanced.

  In polyurethane foam, polyol and isocyanate, which are liquid raw materials, are injected into the wall surface using an injection machine equipped with a mixing head. Immediately after the injection, the mixed raw material has fluidity and flows through the wall surface, but the reaction proceeds and cures with time. The change in fluidity of the mixed raw material from mixing to curing affects the heat insulating performance and the filling property to the refrigerator casing.

  For example, if the reaction is too fast, the raw material will not reach every corner of the refrigerator case, resulting in poor filling. As a result, in addition to the loss of heat insulation performance at that portion, the housing strength also decreases. On the other hand, if the reaction is too slow, the curing time, that is, the time required for curing is required, which results in poor productivity and high cost.

  Moreover, cyclopentane which does not destroy ozone is widely used as a foaming agent for polyurethane foam for refrigerators. Cyclopentane has a boiling point of about 49 ° C. at substantially atmospheric pressure, and is vaporized by the reaction heat of the raw material and heat from the foaming jig from the outside during the polyurethane foaming process.

  For this reason, the temperature of the foaming jig is adjusted to approximately 40 ° C. As a means for adjusting the temperature, there is a method in which a foaming jig is passed through a curing furnace adjusted to a predetermined temperature by hot air, but there is a concern that the temperature distribution becomes large.

  On the other hand, the heat insulating performance of the polyurethane foam heat insulating material is determined by the thermal conductivity of the polyurethane resin, the thermal conductivity of the gas in the bubbles, the bubble diameter, and the like. Among these, the gas thermal conductivity in the bubbles is greatly influenced by the gas composition existing in the bubbles, and cyclopentane is not preferable because of its high thermal conductivity compared to Freon gas that has been used as a blowing agent in the past.

  However, at present, when environmental protection is a problem on a global scale, it is currently impossible to use CFCs that have a large environmental load.

  Therefore, a method of reducing the bubble diameter has been proposed in order to improve the performance of the polyurethane foam heat insulating material (for example, see Patent Document 1).

  FIG. 3 is a schematic configuration diagram of a conventional rigid polyurethane foam production apparatus. The polyol component is sent from the polyol component tank 1 to the gas loading device 3 provided in the pipe via the metering pump 2, and the gas is introduced through the gas loading device 3 and then stirred by the static mixer 4. Then, it is sent directly to the mixing head 5 as a gas-liquid dispersion system.

  On the other hand, the isocyanate component is sent from the tank 6 to the mixing head 5 via the metering pump 7.

  And a rigid polyurethane foam is produced by making the polyol component and isocyanate component of a gas-liquid dispersion system react with the mixing head 5, and discharging.

According to such an apparatus for producing a rigid polyurethane foam, it is possible to foam as a gas-liquid dispersion system in a short time by using a gas as compared with the case where liquids are made into an emulsion dispersion system. From this, the bubbles in each component can be miniaturized in a short time, the resulting foam can be miniaturized and uniform, and the thermal conductivity can be reduced.
JP 2007-269820 A

  However, in the above conventional configuration, the raw material sent from the tank 1 to the mixing head 5 via the metering pump 2 forms a circulation circuit that is returned to the tank again, and is discharged out of the circuit only when polyurethane foam is produced. . If a gas is mixed with the circulating raw material, the gas concentration in the raw material becomes excessive. Further, in order to properly control the gas concentration in the raw material, it is preferable to mix the gases only at the time of discharge. However, in order to mix the gases uniformly between the static mixer 4 and the mixing head 5, a certain mixing time is required. However, there is a problem in that the amount of raw material staying in the pipe increases.

  An object of this invention is to provide the manufacturing method of the foaming polyurethane excellent in quality, and the heat insulation box using the same in view of the said subject.

  In order to achieve the above object, a method for producing a foamed polyurethane according to the present invention is a method in which a first raw material and a second raw material are mixed by a mixing head, and the boiling point at approximately atmospheric pressure is upstream of the mixing head. Is mixed with the third raw material containing the foaming agent of less than zero degrees and the first raw material.

  The first raw material and the third raw material are mixed in the mixer, and then mixed with the second raw material in the mixing head and discharged out of the system. Since the third raw material contains a foaming agent that easily vaporizes at approximately atmospheric pressure, foaming starts immediately after discharge.

  That is, since the third raw material contains the foaming agent in a different route from the first circuit, a sufficient mixing time can be ensured and uniform mixing can be achieved. For this reason, since an appropriate amount of foaming agent can be contained in the foamed polyurethane raw material, a high-quality foamed polyurethane can be obtained. Moreover, the heat insulation box using the same can be manufactured.

  According to the present invention, when carbon dioxide having a low boiling point is used as a foaming agent, an appropriate amount can be contained in the raw material, and the cell size and density of the foamed polyurethane can be reduced. The quality of the heat insulation box using it can be remarkably improved.

  The invention of the method for producing a foamed polyurethane according to claim 1 of the present invention is to mix the first raw material and the second raw material with a mixing head, and the boiling point at substantially atmospheric pressure upstream of the mixing head. Is mixed with a third raw material containing a foaming agent of zero degrees or less and the first raw material, and after the first raw material and the third raw material are mixed, in a mixing head It is mixed with the second raw material and discharged out of the system. Since the third raw material contains a foaming agent that easily vaporizes at approximately atmospheric pressure, foaming starts immediately after discharge.

  That is, since the third raw material contains the foaming agent in a route different from the main raw material route of the first raw material and the second raw material, a sufficient mixing time can be secured and uniform mixing can be achieved. For this reason, since an appropriate quantity of a foaming agent can be contained in a foaming polyurethane raw material, a high quality foaming polyurethane heat insulating material can be manufactured.

  The invention of the method for producing a foamed polyurethane according to claim 2 is characterized in that, in the invention according to claim 1, the third raw material is a mixture of the first raw material and a foaming agent. The first raw material and the third raw material have substantially the same basic physical properties such as density and viscosity.

  That is, in order to mix the first raw material and the foaming agent, precise management such as pressure, temperature, and mixing time is required, but the mixing of the first raw material and the third raw material is relatively easy. , Can be mixed uniformly. For this reason, since an appropriate quantity of a foaming agent can be contained in a foaming polyurethane raw material, a further high-quality foaming polyurethane heat insulating material can be manufactured.

  The invention of the method for producing foamed polyurethane according to claim 3 is characterized in that, in the invention according to claim 1 or 2, the temperature of the third raw material is lower than that of the first raw material. In order to dissolve a foaming agent that is easily vaporized at approximately atmospheric pressure in a liquid such as a polyurethane raw material, a low temperature is preferable from Henry's law.

  However, when the temperature of the first raw material is lowered, when the second raw material is mixed with the mixing head, the average temperature of the whole raw material is lowered, and the reaction speed is reduced, so that the curing time becomes longer. For this reason, the foaming agent dissolved in the raw material is easily released into the atmosphere, and in the worst case, a large void is generated.

  From this, the foaming agent is prepared by mixing the foaming agent in advance with the first raw material whose temperature has been lowered by another route to prepare the third raw material and mixing it with the first raw material flowing through the first circuit. Can be uniformly mixed in the raw material, and an appropriate amount of foaming agent can be contained in the foamed polyurethane raw material, so that a higher quality foamed polyurethane heat insulating material can be produced.

  The invention of the method for producing foamed polyurethane according to claim 4 is characterized in that, in the invention according to any one of claims 1 to 3, the foaming agent is carbon dioxide, Carbon dioxide has a boiling point at about atmospheric pressure of 79 ° C. below freezing point, has a very high foaming power, is chemically stable, and is excellent in environmental resistance. Since this is used as a foaming agent and uniformly mixed in the raw material, a higher quality foamed polyurethane heat insulating material can be produced.

  The invention of the heat insulation box according to claim 5 is a heat insulation box provided with the polyurethane foam manufactured by the method according to any one of claims 1 to 4, and is a high quality heat insulation box. Can be manufactured.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is an explanatory view showing a method for producing a raw material separation type polyurethane foam in Embodiment 1 of the present invention. FIG. 2 is an explanatory diagram showing a method for producing a branched material polyurethane foam according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the polyurethane raw material includes a first raw material 101 and a second raw material 102. Specifically, there are a polyol component and an isocyanate component. In the present embodiment, the first raw material 101 is a polyol component and the second raw material 102 is an isocyanate component, but this may be reversed. In addition, cyclopentane, water, a foam stabilizer, a catalyst, etc. are mixed with the 1st raw material 101 which is a polyol component previously.

  The first raw material 101 and the second raw material 102 are supplied to the mixing head 103, mixed there, and then injected into a heat insulating housing 104 represented by an electric refrigerator-freezer, a vending machine, and the like. Note that although the single mixing head 103 is described, a plurality of mixing heads 103 may be used in view of the shape and structure of the heat insulating housing 104.

  While the first raw material 101 is conveyed to the mixing head 103, it is mixed with the third raw material 105. The third raw material 105 is obtained by adding the foaming agent 106 to the first raw material 101, and is set at a temperature lower than that of the first raw material 101. As the foaming agent 106, it is preferable to use a substance having a boiling point of approximately zero degrees or less at substantially atmospheric pressure, and use carbon dioxide in view of ease of handling, environmental resistance, and thermal conductivity in a gaseous state.

  For this reason, when the third raw material 105 is placed in a substantially atmospheric pressure atmosphere, the foaming agent 106 is vaporized and bubbles are generated. Therefore, in order to mix the first raw material 101 and the third raw material 105, it is preferable to use a liquid-liquid mixer 107 typified by a static mixer in a high pressure atmosphere of about 8 to 13 MPa. Under such conditions, the physical properties such as the viscosity and density of the first raw material 101 and the third raw material 105 that affect the mixing property are substantially the same and are mixed well.

  In order to prepare the third raw material 105, the first raw material 101 is separated as shown in FIG. 1, and the foaming agent 106 is mixed with the foaming agent mixer 108, as shown in FIG. There is a method of mixing the first raw material 101 by a branched sub route. In this case, the first raw material 101 is cooled by providing the heat exchanging means 109, so that the solubility of the foaming agent 106 is improved and the third raw material 105 becomes homogeneous.

  As described above, the first raw material 101 and the second raw material 102 are mixed by the mixing head 103, and contain the foaming agent 106 having a boiling point of approximately zero or less at approximately atmospheric pressure on the upstream side of the mixing head 103. The third raw material 105 and the first raw material 101 are mixed. After the first raw material 101 and the third raw material 105 are mixed, the mixing raw material 102 is mixed with the second raw material 102 by the mixing head 103. It is discharged outside. Since the third raw material 105 contains a foaming agent 106 that easily vaporizes at approximately atmospheric pressure, foaming starts immediately after discharge.

  That is, since the third raw material 105 contains the foaming agent 106 in a route different from the main raw material route of the first raw material 101 and the second raw material 102, a sufficient mixing time can be secured and mixed uniformly. be able to. For this reason, since an appropriate amount of the foaming agent 106 can be contained in the foamed polyurethane raw material, a high-quality foamed polyurethane can be produced.

  As mentioned above, since the manufacturing method and heat insulation box of the polyurethane foam concerning this invention can mix the carbon dioxide which is a low boiling-point foaming agent uniformly to a raw material, a polyurethane foam heat insulating material and heat insulation using the same The quality of the box can be improved. For this reason, it is possible to promote energy saving of a thermal device such as a refrigerator and provide environmentally friendly products.

Explanatory drawing which shows the manufacturing method of the raw material separation type foaming polyurethane in Embodiment 1 of this invention Explanatory drawing which shows the manufacturing method of the raw material branched type polyurethane foam in Embodiment 1 of this invention Schematic configuration diagram of conventional rigid polyurethane foam production equipment

Explanation of symbols

101 First raw material (polyol component)
102 Second raw material (isocyanate component)
103 Mixing head 104 Heat insulation box (refrigerator)
105 Third raw material 106 Foaming agent (carbon dioxide)

Claims (5)

A first raw material and a second raw material are mixed by a mixing head, and a third raw material containing a blowing agent having a boiling point of approximately zero degrees or less at approximately atmospheric pressure upstream of the mixing head and the first raw material A method for producing foamed polyurethane, comprising mixing raw materials. The method for producing a foamed polyurethane according to claim 1, wherein the third raw material is obtained by mixing a foaming agent with the first raw material. The method for producing a polyurethane foam according to claim 1 or 2, wherein the temperature of the third raw material is lower than that of the first raw material. The method for producing a polyurethane foam according to any one of claims 1 to 3, wherein the foaming agent is carbon dioxide. The heat insulation box provided with the polyurethane foam manufactured by the method as described in any one of Claim 1 to 4.

Images