JP2009242535A - Manufacturing method of hard polyurethane foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a hard polyurethane foam whose cell diameter is made microcellular. <P>SOLUTION: The manufacturing method of a hard polyurethane foam comprises introducing microbubbles generated by a microbubble generation apparatus to a polyol component before mixing of a polyisocyanate component and the polyol component, when the hard polyurethane foam is manufactured by mixing the polyisocyante component and the polyol component containing a polyol, water, a catalyst, a foam stabilizer, and other auxiliary components, and thereafter, spray foaming the mixture. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a rigid polyurethane foam obtained by spray foaming, and more specifically, by introducing fine bubbles generated by a fine bubble generator into a polyol component, the cell diameter of the obtained foam is reduced. The present invention relates to a method for producing a rigid polyurethane foam that is fine (hereinafter also referred to as “microcellular”).

  Conventionally, a rigid polyurethane foam obtained by spray foaming is excellent in heat insulation, workability, and the like, and is widely used as a heat insulating material and a structural material for houses, refrigerated warehouses, and the like. The foam is usually produced by reacting a polyisocyanate component and a polyol component in the presence of a foaming agent, and hydrofluorocarbon (HFC) and / or carbon dioxide is used as the foaming agent.

  However, because HFC has a high global warming potential (GWP), its use will be regulated in the future. Carbon dioxide is an environmentally friendly foaming agent, but hard urethane foam spray foamed with carbon dioxide generated by the reaction of water and polyisocyanate has better adhesive properties than those using hydrofluorocarbon (HFC). There is a problem in workability such as a decrease in heat resistance, and the heat conductivity is high and the heat insulation is poor.

  On the other hand, Non-Patent Document 1 considers the contribution of radiation to the thermal conductivity of rigid urethane foam, and shows that the smaller the cell diameter, the smaller the radiation. That is, if the cell diameter can be reduced, the radiation is also reduced. As a result, the thermal conductivity can be lowered and a foam having excellent heat insulation can be obtained.

  In order to reduce the cell diameter, for example, in Non-Patent Document 2, the air entrained in the process of stirring the urethane raw material acts as the core of bubbles during foaming, and the more the core, the more urethane foam cells. That is, it shows that the cell becomes finer.

  Further, in Patent Document 1, in order to reduce the cell diameter, the particle diameter of bubbles to be introduced is 20 μm or less, preferably 10 μm or less. As a gas introduction method, a gas loading device including a static mixer and a forced stirring blade is used. It is shown.

  And in this literature 1, since pentane which is also a viscosity reducing agent is used as a foaming agent, the viscosity of the polyol component can be reduced to 200 mPa · s or less at 25 ° C. Therefore, the above gas loading device is used. Thus, bubbles of 20 μm or less can be introduced.

However, when carbon dioxide generated by the reaction between polyisocyanate and water is used as a blowing agent, the viscosity of the polyol component containing water is as high as 500 mPa · s or more at 25 ° C. As a result, there is a problem that it is difficult to introduce bubbles of 20 μm or less using the gas loading device.
JP 2007-269820 A LD Booth, “Radiation Contribution as an Element of Thermal Conductivity”, Polyurethanes World Congress 1987, p. 85-90 B. Kanner and TG Decker, “Urethane Foam Formation-Role of the Silicone Surfactant”, J. Cell. Plast. 5, (1969), p. 32-39

  In the present invention, a rigid polyurethane foam is obtained using carbon dioxide generated by the reaction of polyisocyanate and water as a foaming agent. In this case, water is preliminarily contained in a polyol component, or third. As a component, it is put into a polyol component. As a result, the viscosity of the polyol component becomes as high as 500 mPa · s or more at 25 ° C. Even if the viscosity of the polyol component is high in this way, it is possible to introduce a predetermined amount of bubbles of 20 μm or less into the polyol component. An object of the present invention is to provide a production method for making the cell diameter of a rigid polyurethane foam obtained by spray foaming into microcellular.

  In the production of a rigid polyurethane foam obtained by mixing a polyisocyanate component and a polyol component containing a polyol, water, a catalyst, a foam stabilizer and other auxiliary components, followed by spray foaming, The generated fine bubbles are introduced into a high viscosity polyol component to generate a large number of bubble nuclei.

  That is, in the method for producing a rigid polyurethane foam according to claim 1 of the present invention, a polyisocyanate component and a polyol component containing a polyol, water, a catalyst, a foam stabilizer and other auxiliary components are mixed and then spray foamed. In the production of the rigid polyurethane foam obtained in this way, before the mixing of the polyisocyanate component and the polyol component, fine bubbles generated by a fine bubble generator are introduced into the polyol component.

  The method for producing a rigid polyurethane foam according to claim 2 is characterized in that the fine bubble generating device is a device for introducing gas through the porous ceramics, and the pore diameter of the porous ceramics is 1 μm or less. To do.

  The method for producing a rigid polyurethane foam according to claim 3 is characterized in that the average particle diameter of the fine bubbles introduced into the polyol component is 20 μm or less.

  The method for producing a rigid polyurethane foam according to claim 4 is characterized in that the introduction amount of fine bubbles is 1 to 20 vol% with respect to the total amount of the polyisocyanate component and the polyol component. .

  The method for producing a rigid polyurethane foam according to claim 5 is characterized in that the gas introduced by the fine bubble generator is any one of air, nitrogen, and carbon dioxide.

  The method for producing a rigid polyurethane foam according to claim 6 is characterized in that the cell diameter of the rigid polyurethane foam is 150 μm or less.

  According to the present invention, even if the polyol component has a high viscosity, a large number of fine bubbles can be introduced into the polyol component. For this reason, the rigid polyurethane foam obtained by spray foaming has a cell diameter of 150 μm or less. Therefore, heat transfer due to radiation can be suppressed, and the thermal conductivity can be reduced to 0.024 w / (m · K) or less despite foaming of carbon dioxide.

  Hereinafter, embodiments of the present invention will be described in detail. In the rigid polyurethane foam obtained by mixing the polyisocyanate component and the polyol component containing polyol, water, catalyst, foam stabilizer and other auxiliary components and spray foaming, After introducing the fine bubbles generated by the fine bubble generator into the polyol component, both are mixed and spray foamed. As a result, the cell diameter of the obtained rigid polyurethane foam can be made microcellular.

  Examples of the fine bubble generator include the following four methods.

1) A static mixer system that pulverizes a gas by a large viscous shear force mainly derived from an overflow generated by complicating the structure in the flow path and generated by the flow driving force of the liquid,
2) Ultrasonic cavitation method,
3) A fine pore system that is generated by press-fitting and dispersing a gas through a porous material having a fine pore diameter,
4) A gas-liquid shearing method in which gas is sheared by high-speed swirling or collision of gas-liquid two phases.

  And this invention manufactures a rigid polyurethane foam using the carbon dioxide which generate | occur | produces by reaction of polyisocyanate and water as a foaming agent, The viscosity of a polyol component is the water addition method (previously to a polyol component). Regardless of whether it is added as a third component), it is as high as 500 mPa · s at 25 ° C. As a result, in the above 1) static mixer system and 2) ultrasonic system, it was difficult to introduce bubbles of 20 μm or less.

  In addition, since the gas-liquid shearing method is large in size, both the high-speed swirling device that swirls the gas-liquid two-phase fluid at high speed to shear the gas or the high-pressure liquid that collides and mixes the high-pressure liquid in the gas-liquid two-phase, It is difficult to attach to a rigid polyurethane foam spray foaming device. Therefore, a small-sized micropore system is preferably used for the spray foaming apparatus.

  The micropore method used as the microbubble generator of the present invention is to introduce a gas through porous ceramics, and the porous ceramics has a pore size of 1 μm or less and a fine and uniform pore size. Preferably, the pore diameter is 0.02 to 0.4 μm. Further, when the pore diameter exceeds 1 μm, it is difficult to generate fine bubbles, and when the pore diameter is less than 0.02 μm, it is difficult to press-fit gas into the polyol component. Examples of the porous ceramic include shirasu porous glass (hereinafter also referred to as “SPG film”) and fine ceramics (hereinafter also referred to as “ceramic filter”).

  The average particle diameter of the fine bubbles introduced into the polyol component by the fine bubble generator of the present invention is 20 μm or less, preferably 10 μm or less. On the other hand, if it exceeds 20 μm, the cell diameter of the obtained rigid polyurethane foam is unlikely to be microcellular.

  Moreover, the introduction amount of fine bubbles is preferably 1 to 20 vol% with respect to the total amount of the polyol component and the polyisocyanate component. If it is less than 1 vol%, it is difficult to become microcellular, and if it exceeds 20 vol%, the spray pattern by the spray gun is likely to become unstable.

  The fine bubble generating device can be installed in a flow path from the polyol component tank to the mixing head. For example, when water and liquid carbon dioxide are introduced in a flow path from a polyol component tank to a mixing head as described in JP-A-2004-107376, water and liquid carbon dioxide It is preferable to install a fine bubble generating device in the flow path from after the introduction to the mixing head, and more preferably in the heating hose provided immediately before the mixing head in the flow path of the polyol component, A microbubble generator is installed.

  Furthermore, when introducing fine bubbles into the polyol component using a fine pore type fine bubble generator, shirasu porous glass (SPG membrane) or fine ceramic with fine pores is used and pressure is applied from a compressed air cylinder. And introduced into the polyol component. The pressure at this time must be at least larger than the pressure of the polyol component flowing in the pipe. For example, when the pressure of the polyol component flowing in the pipe is 6.5 to 7.5 Mpa, the pressure for introducing the gas into the polyol component using a fine pore type fine bubble generator is 7 to 8 Mpa than the pressure of the polyol component. Must also be large.

  The average particle diameter of the fine bubbles introduced into the polyol component can be measured by, for example, an image type particle size distribution meter.

  The present invention is to produce a rigid polyurethane foam using carbon dioxide generated by the reaction of polyisocyanate and water as a blowing agent, that is, water is added to the polyol component in advance, As described in JP-A-2004-107376, water or liquid carbon dioxide may be added to the polyol component before mixing of the polyisocyanate component and the polyol component. The amount of water used and the types and amounts of polyols, polyisocyanates, catalysts, flame retardants and the like used are as described in JP-A-2004-107376.

  In addition, as described in JP-A-2004-107376, a static mixer may be provided between the position where the liquid component of carbon dioxide and water is added to the polyol component and the mixing head. Water and carbon dioxide in a liquid state can be efficiently mixed in the components.

  The invention is illustrated in more detail by the examples, but should not be construed as limiting the invention.

  The raw materials used in the examples and comparative examples are as follows.

Polyisocyanate: Polymeric diphenylmethane diisocyanate (NCO%: 31.0%)
Polyol A: Polyethylene terephthalate polyester polyol (hydroxyl value 110)
Polyol B: Mannich polyether polyol (hydroxyl value 315)
Silicone foam stabilizer: manufactured by Toray Dow Corning Co., Ltd., SH193
Catalyst A: Pentamethyldiethylenetriamine (Air Products Co., Ltd., POLYCAT 5)
Catalyst B: Tris (dimethylaminopropyl) hexahydro-s-triazine (Air Products, Polycat 41)
Catalyst C: Lead octylate (Dainippon Ink Chemical Co., Ltd., Pb-Oc)
Flame retardant: Trischloropropyl phosphate (manufactured by Daihachi Chemical Co., Ltd., TMCPP)
Thickener: Propylene carbonate

  Next, an apparatus for producing a rigid polyurethane foam will be described with reference to FIG.

  The polyisocyanate component 1 is measured from a tank 2 by a metering pump 3 connected via a pipe 4, and transferred to a mixing head 5 via a heater unit 18 and a heating hose 19 for heating to a set temperature. .

  The polyol component 11 is measured by a metering pump 14 connected from a tank 12 via a pipe 13, and heated to a set temperature, a heater unit 10, a heating hose 9, a fine bubble generating device 20, a heating hose 9 Then, it is transferred to the mixing head 5.

  Water in the water storage tank 15 is metered by a metering pump 16 that operates in conjunction with each pump, is introduced into the polyol component through a pipe 17 connected to the pipe 13, and is being transferred in a flow path leading to the mixing head 5. Mixed into the polyol component.

  The carbon dioxide in the liquid state of the carbon dioxide cylinder 6 is measured by a metering pump 7 that operates in conjunction with each pump, is introduced into the polyol component through a pipe 8 connected to the pipe 13, and reaches the mixing head 5 In the polyol component being transferred.

  As the microbubble generator 20, a micropore system is adopted. Specifically, as shown in FIG. 1, a shirasu porous glass (SPG film) or a ceramic filter (CF) is disposed between the heater unit 10 and the mixing head 5 ( That is, it is installed at a predetermined position of the heating hose 9).

  Then, as shown in FIG. 2, a gas (corresponding to “high-pressure gas” in FIG. 2) that becomes fine bubbles is introduced into the polyol component using the fine bubble generator 20. The amount of gas introduced was measured with a mass flow meter.

  The polyol component in which the polyisocyanate component, carbon dioxide and water are mixed is maintained at a temperature and pressure of 50 ° C. and 7 MPa in a heating hose. Further, the polyol component is introduced with fine bubbles of 20 μm or less by the fine pore type fine bubble generator 20, and then the polyol component and the polyisocyanate component into which the fine bubbles are introduced are mixed in the mixing head 5. Then, it is ejected into the atmosphere with liquid or bubble mist. Thereafter, it is cured by reaction to form a rigid polyurethane foam.

(Example 1)
A polyol component was prepared according to the formulation described in Table 1. Further, as the fine pore type generator 20, a module equipped with Shirasu porous glass (referred to as “SPG membrane” in Table 1) having a pore diameter of 0.4 μm manufactured by SPG Techno Co., Ltd. is used. Air from a compressed air cylinder at a pressure of 8 MPa and 10 vol% of the total of the polyisocyanate component and the polyol component was introduced into the polyol component as a high-pressure gas shown in FIG.

  Further, since the used SPG film has a low withstand pressure of 1 MPa, a metal tube having small holes on the outside and inside of the SPG film was provided as shown in FIG. 3 in order to prevent breakage. 3 (a) is a state diagram provided in the micro-hole type generator 20, and FIG. 3 (b) is for explaining the structure of FIG. 3 (a). FIG.

  In the polyol component after the fine bubbles were introduced by the generator 20, the average particle diameter of the fine bubbles was measured. The measurement method is the addition of fine bubbles by the generator 20 to the polyol component of the formulation shown in Table 1 in which carbon dioxide in the liquid state is not added to the polyol component, and the average of the bubbles in the polyol component extracted from the mixing head 5 The particle size was measured with an image analysis type particle measurement system VisiSizer manufactured by Nippon Laser Corporation. As a result, the average particle diameter of the fine bubbles introduced into the polyol component was 3 μm.

  According to the formulation shown in Table 1, the polyol component and the polyisocyanate component are mixed using the apparatus shown in FIG. 1 (Graco Corp. FF1600 foaming machine), and the foam thickness becomes 30 mm on a 12 mm thick plywood. Thus, a rigid polyurethane foam was obtained by spray foaming.

  From the obtained foam, density, thermal conductivity, and cell size were measured. As a result, as shown in Table 1, the foam density was 27.5 kg / m3, the average cell size measured with an electron microscope was 145 μm, and the thermal conductivity after 24 hours of foaming was 0.0239 W / (m · K )Met.

The physical properties shown in Table 1 were measured by the following methods.
Foam density (kg / m ³ ): Conforms to JIS A-9511 Thermal conductivity (W / m · K): Average temperature using Auto ΛHC-074 manufactured by Eihiro Seiki Co., Ltd. by heat flow meter method shown in JIS A-1412 Measured at 23 ° C.
Cell size: Measured with an electron microscope.

(Example 2)
A rigid polyurethane foam was obtained by spraying in the same manner as in Example 1 except that the amount of introduced air was 20 vol%. The physical properties of the obtained foam were measured in the same manner. As shown in Table 1, the density of the foam was 27.7 kg / m3, the average cell size measured with an electron microscope was 140 μm, The thermal conductivity after time was 0.0238 W / (m · K).

  The average particle diameter of the fine bubbles introduced into the polyol component was also measured by the same method as in Example 1. As a result, it was 3 μm.

(Example 3)
A rigid polyurethane foam was obtained by spraying in the same manner as in Example 1 except that the introduced gas (high-pressure gas shown in FIG. 2) was carbon dioxide and the amount of introduced carbon dioxide was 15 vol%. The physical properties of the obtained foam were measured in the same manner. As shown in Table 1, the density of the foam was 27.0 kg / m3, the average cell size measured with an electron microscope was 140 μm, The thermal conductivity after time was 0.0236 W / (m · K).

  The average particle diameter of the fine bubbles introduced into the polyol component was also measured by the same method as in Example 1. As a result, it was 4 μm.

(Example 4)
A rigid polyurethane foam was obtained by spraying in the same manner as in Example 1 except that the introduced gas (high-pressure gas shown in FIG. 2) was nitrogen and the amount of introduced nitrogen was 15 vol%. The physical properties of the obtained foam were measured in the same manner. As shown in Table 1, the density of the foam was 27.4 kg / m3, the average cell size measured with an electron microscope was 145 μm, The thermal conductivity after time was 0.0238 W / (m · K).

  The average particle diameter of the fine bubbles introduced into the polyol component was also measured by the same method as in Example 1. As a result, it was 4 μm.

(Example 5)
Spraying was performed in the same manner as in Example 2, except that the fine bubble generator 20 was a ceramic filter (referred to as “CF” in Table 1) having a pore diameter of 0.05 μm manufactured by Noritake Co., Ltd. A rigid polyurethane foam was obtained. The physical properties of the obtained foam were measured in the same manner. As shown in Table 1, the density of the foam was 27.3 kg / m 3, the average cell size measured with an electron microscope was 140 μm, and the foam 24 The thermal conductivity after time was 0.0237 W / (m · K).

  The average particle diameter of the fine bubbles introduced into the polyol component was also measured by the same method as in Example 1. As a result, it was 4 μm.

  Note that the ceramic filter having a pore diameter of 0.05 μm manufactured by Noritake Company Limited has a pressure resistance higher than 1 Mpa, and therefore it is not necessary to use an outer / inner metal tube as shown in FIG.

(Comparative Example 1)
A rigid polyurethane foam was obtained by spraying in the same manner as in Example 1 except that a microporous generator was not used. The physical properties of the obtained foam were measured in the same manner. As shown in Table 1, the density of the foam was 27.7 kg / m3, the average cell size measured with an electron microscope was 255 μm, The thermal conductivity after time was 0.0270 W / (m · K).

  As described above, Comparative Example 1 did not introduce fine bubbles, resulting in a large cell diameter and high thermal conductivity.

(Comparative Example 2)
A rigid polyurethane foam was obtained by spraying in the same manner as in Example 1 except that the amount of introduced air was 0.5 vol%. The physical properties of the obtained foam were measured in the same manner. As shown in Table 1, the foam density was 27.2 kg / m3, the average cell size measured with an electron microscope was 210 μm, The thermal conductivity after time was 0.0255 W / (m · K).

  As described above, Comparative Example 2 resulted in a large cell diameter and high thermal conductivity because the amount of air introduced by the micropore method was less than 1 vol%.

  The average particle diameter of the fine bubbles introduced into the polyol component was also measured by the same method as in Example 1. As a result, it was 3 μm.

(Comparative Example 3)
A rigid polyurethane foam was obtained by spraying in the same manner as in Example 1 except that the pore size of the SPG film was changed to 2 μm. The physical properties of the obtained foam were measured in the same manner. As shown in Table 1, the density of the foam was 25.0 kg / m3, the average cell size measured with an electron microscope was 240 μm, The thermal conductivity after time was 0.0268 W / (m · K).

  As described above, Comparative Example 3 resulted in a large cell diameter and high thermal conductivity because the diameter of the micropores by the micropore method exceeded 1 μm.

  The average particle diameter of the fine bubbles introduced into the polyol component was also measured by the same method as in Example 1. As a result, it was 25 μm.

(Comparative Example 4)
Spraying was performed in the same manner as in Example 1, except that the amount of introduced air was 30 vol%. However, since the introduction amount of air exceeded 20 vol%, the spray pattern was changed, so that a rigid urethane foam having a uniform thickness could not be obtained. Therefore, the density, cell diameter, and thermal conductivity could not be measured.

  The average particle diameter of the fine bubbles introduced into the polyol component was also measured by the same method as in Example 1. As a result, it was 4 μm.

It is a figure which shows the one aspect | mode of the manufacturing apparatus of a rigid polyurethane foam. 3 is a diagram for explaining a microbubble generator 20. FIG. It is a figure which shows the one aspect | mode which provided the metal tube in the outer side and inner side of a SPG film | membrane (or CF).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polyisocyanate component 2 Polyisocyanate component tank 3 Pump 4 Piping 5 Mixing head 6 Liquid carbon dioxide cylinder 7 Metering pump 8 Piping 9 Heating hose 10 Heater 11 Polyol component 12 Polyol component tank 13 Piping 14 Metering pump 15 Water storage tank 16 Metering pump 17 Piping 18 Heater 19 Heating hose 20 Fine bubble generator

Claims (6)

A polyisocyanate component;
In the production of rigid polyurethane foam obtained by spray foaming after mixing with polyol components including polyol, water, catalyst, foam stabilizer and other auxiliary components,
A method for producing a rigid polyurethane foam, comprising introducing fine bubbles generated by a fine bubble generator into a polyol component before mixing the polyisocyanate component and the polyol component. The microbubble generator is a device that introduces gas through porous ceramics,
2. The production method according to claim 1, wherein the pore diameter of the porous ceramic is 1 μm or less.   The production method according to claim 1 or 2, wherein the average particle diameter of the fine bubbles introduced into the polyol component is 20 µm or less.   The production method according to any one of claims 1 to 3, wherein the amount of fine bubbles introduced is 1 to 20 vol% with respect to the total amount of the polyisocyanate component and the polyol component.   The manufacturing method according to any one of claims 1 to 4, wherein the gas introduced by the fine bubble generator is any one of air, nitrogen, and carbon dioxide.   A rigid polyurethane foam, wherein the cell diameter of the rigid polyurethane foam according to any one of claims 1 to 5 is 150 µm or less.