JP2004051908A - Method for manufacturing rigid polyurethane foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem in which a polyester-based polyol is hydrolyzed or a component is separated while the polyester-based polyol is used as a polyol and desired foam physical properties are hardly obtained. <P>SOLUTION: This method for manufacturing a rigid polyurethane foam comprises mixing the polyol component containing at least the polyester-based polyol and a polyisocyanate component in a mixing head and foaming by spraying. The method is characterized in that water as a foaming agent is mixed into the polyol component in a transportational flow path of the polyol component to the mixing head. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a rigid polyurethane foam, and more particularly, to a method for producing a rigid polyurethane foam using water as a foaming agent.
[0002]
[Prior art]
Rigid polyurethane foam has excellent heat insulation properties, moldability, self-adhesiveness, etc., and is used as a heat insulation material for buildings such as homes and refrigerators, vending machines, refrigerators, etc. It is used as embankment for building or embankment.
In the production of rigid polyurethane foam, hydrochlorofluorocarbon (HCFC) has been used as a main blowing agent, but this will destroy the ozone layer and will not be used in the future. Furthermore, in recent years, hydrofluorocarbons (HFCs) that do not destroy the ozone layer have been proposed as alternatives to HCFCs, but have the disadvantage of a large greenhouse effect. As a foaming agent other than HCFC and HFC, for example, hydrocarbon can be mentioned, but since this has explosive flammability, there remains a problem in terms of safety.
For this reason, it is common to use carbon dioxide generated by the reaction with isocyanate using water as a blowing agent.
[0003]
[Problems to be solved by the invention]
However, in the technology using water as a foaming agent, water is dissolved and dispersed in a polyol together with a catalyst and a foam stabilizer in advance to form a polyol component. In producing a rigid polyurethane foam, the polyol component and the polyisocyanate component are mixed and foamed. However, when a polyester-based polyol is used as this polyol, problems such as hydrolysis of the polyester-based polyol or separation of components occur with time depending on the storage and storage conditions, and desired foam properties are obtained. There is a problem that is hard to find.
In addition, although there is no particular problem in the production of rigid polyurethane foam in a factory, when a portable foaming machine and a polyol component and a polyisocyanate component are carried in a tank and foamed on site at a construction site, an embankment site, etc. There is a problem that hydrolysis is promoted because the components are in a state of being stacked in a tank.
[0004]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, in order to improve the premix stability of the polyol component, water was not previously mixed into the polyol component, and a rigid polyurethane foam was produced. When the water is added and mixed with the polyol component in the transfer flow path from the polyol component tank to the mixing head, a rigid polyurethane foam with a stable water formulation can be obtained even for a polyurethane material stored for a long time. I found what I can do.
[0005]
That is, the present invention relates to a method for producing a rigid polyurethane foam in which a polyol component containing at least a polyester-based polyol and a polyisocyanate component are mixed with a mixing head and spray-foamed, wherein water as a foaming agent is mixed with a mixing head. A rigid polyurethane foam, which is mixed with a polyol component in a flow path of the polyol component leading to the above.
[0006]
In the present invention, it is preferable to provide a static mixer in the flow path of the polyol component reaching the mixing head. When a static mixer is used, the foaming agent can be more uniformly mixed in the polyol component, and can be mixed in a relatively short time. It is preferable to provide a static mixer between the mixing head.
[0007]
In the present invention, when water as a foaming agent is added in the flow path of the polyol component reaching the mixing head, the polyol component and the polyisocyanate component may be mixed at a predetermined temperature controlled by a heater. For this reason, it is preferable to add water before the heater for controlling the liquid temperature of the polyol component.
[0008]
In the present invention, a blowing agent other than water can be used in combination as the blowing agent.
As other blowing agents, conventionally known blowing agents can be used, for example, hydrocarbons such as butane, pentane and hexane, carbon dioxide, HFC-245fa, HFC-365mfc, and fluorine-based materials such as HFC-134a. And the like. These can be used alone or in combination of two or more foaming agents. Preferably, a combination of water and two kinds of fluorine-based compounds or a combination of water, carbon dioxide and a fluorine-based compound is used.
The foaming agent that is liquid at normal temperature and normal pressure may be mixed in the polyol component in advance, but like the water, the foaming agent is also mixed in the polyol component in the flow path of the polyol component leading to the mixing head. Is preferred. More preferably, water is added from the same position as water.
[0009]
The polyol used in the present invention can be used alone or in combination with a polyester polyol and a polyether polyol.
[0010]
Examples of the polyester polyol used in the present invention include, for example, ethylene glycol, propanediol, butanediol, diethylene glycol, dipropylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentyl glycol, At least one compound having at least two hydroxyl groups such as methyl-1,5-pentanediol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, and bisphenol A, and, for example, adipic acid, malonic acid, succinic acid, Acid, tartaric acid, pimelic acid, sebacic acid, oxalic acid, phthalic acid, terephthalic acid, azelaic acid, trimellitic acid, glutaconic acid, α-hydromuconic acid, β-diethylsa A compound produced by a known method using at least one compound having at least two or more carboxyl groups, such as succinic acid, hemimelitic acid, and 1,4-cyclohexanedicarboxylic acid.
[0011]
Further, in addition to the above polyester polyol, a polyester polyol produced by transesterification of a polyalkylene terephthalate polymer with a low molecular weight diol can also be used. In addition, as a low molecular weight diol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, butanediol, glycerol, trimethylolpropane, cyclohexanedimethanol and the like can be mentioned.
[0012]
Examples of the polyether polyol include those obtained by addition-polymerizing a monomer such as an alkylene oxide by a known method using at least one of the active hydrogen compounds exemplified above as an initiator. In addition, as a monomer used for an addition polymerization reaction, ethylene oxide, propylene oxide, glycidyl ether, methyl glycidyl ether, t-butyl glycidyl ether, phenyl glycidyl ether and the like can be mentioned.
[0013]
As the polyisocyanate of the present invention, an aromatic polyisocyanate, an aliphatic diisocyanate or the like is used.
Examples of the aromatic polyisocyanate include 2,4′-diphenyl ether diisocyanate, 4,4′-diphenyl ether diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and 4,6-dimethyl-1,3-phenylene diisocyanate 4,4'-dibenzyl diisocyanate, 9,10-anthracene diisocyanate, 3,3'-dimethyl-4,4'-diphenyl diisocyanate, xylylene diisocyanate, 2,6'-dimethyl 4,4'-diphenyl diisocyanate, Xylylene diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, and the like.
In addition, examples of the aliphatic diisocyanate include tetramethylene diisocyanate, hexamethylene diisocyanate, and the like. Further, examples of the alicyclic diisocyanate include isophorone diisocyanate, hydrogenated TDI (toluene diisocyanate), hydrogenated MDI (diphenylmethane diisocyanate) and the like. Further, the aromatic polyisocyanate, aliphatic diisocyanate or alicyclic diisocyanate in which a part of the isocyanate group is modified to urethane and / or urea may be used, and a part of the isocyanate group is buret, allophanate, Those modified with carbodiimide, oxaziridone, acid, imide and the like may be used.
[0014]
Examples of the catalyst added to the polyol component used in the present invention include dimethylethanolamine, triethylenediamine, dimethylcyclohexylamine, 1,2-dimethylimidazole, pentamethyldiethylenetriamine, and bis (2-dimethylaminoethyl) ether. An amine catalyst can be used, and a so-called foaming catalyst which promotes a reaction between isocyanate and water, such as pentamethyldiethylenetriamine and bis (2-dimethylaminoethyl) ether, is particularly preferable. Further, a metal catalyst such as lead octylate and dibutyltin dilaurate, and an isocyanuration catalyst such as tris (dimethylaminopropyl) hexahydro-S-triazine, potassium acetate, and potassium octylate can also be used. These can of course be used in combination.
[0015]
Further, additives such as a silicone-based foam stabilizer, a flame retardant, and a compatibilizer may be optionally added to the polyol component.
[0016]
Next, an apparatus for producing a rigid polyurethane foam will be described with reference to FIG.
The polyisocyanate component is measured by a measuring pump 3 connected via a pipe 4 from a tank 2 and transferred to a mixing head 5 via a heater 18 and a heating hose 19 for heating to a set temperature. On the other hand, the polyol component is measured from a tank 12 by a measuring pump 14 connected via a pipe 13, and is transferred to a mixing head 5 via a heater unit 10 for heating to a set temperature and a heating hose 9. .
The water in the water storage tank 15 is measured by a metering pump 16 operating in conjunction with each pump, added to the polyol component through a pipe 17 connected to the pipe 13, and being transferred in a flow path to the mixing head 5. It is mixed into the polyol component. If a static mixer is provided between the position where the water is added and the mixing head, the mixing efficiency is further improved.
The polyol component in which the polyisocyanate component and the water are mixed is kept at 20 to 70 ° C. and 5 to 15 MPa in the flow path leading to the mixing head 5, and the two are colliding and mixed in the mixing head 5 to form a liquid in the atmosphere. Alternatively, it is jetted with a foamy mist, and then is cured by reaction to form a rigid polyurethane foam.
When water and another blowing agent are used in combination, they may be mixed in advance in the polyol component or added during the transfer of the polyol component in the same manner as in the case of water.
[0017]
Hereinafter, the present invention will be described in more detail based on examples and comparative examples, but the present invention is not limited to these examples.
[0018]
The raw materials used in the examples and comparative examples are as follows.
Polyisocyanate: 152 parts by weight of polymethylene polyphenylisocyanate (manufactured by Nippon Polyurethane Co., Ltd.)
Polyol A: 75 parts by weight of polyethylene terephthalate-based polyester polyol (hydroxyl value 110),
Polyol B: 25 parts by weight of Mannich-based polyether polyol (hydroxyl value: 315),
Foam stabilizer: 1 part by weight of a silicone foam stabilizer (L5420, manufactured by Nippon Unicar Co., Ltd.)
Catalyst A: 5 parts by weight of bis (2-dimethylaminoethyl) ether (Kaolyser No. 12 manufactured by Kao Corporation)
Catalyst B: 1 part by weight of tris (dimethylaminopropyl) hexahydro-S-triazine (Polycat 41, manufactured by Air Products Co., Ltd.)
Catalyst C: 3 parts by weight of lead octylate (Pb-Oc, manufactured by Dainippon Ink and Chemicals, Inc.)
Flame retardant: 30 parts by weight of trischloropropyl phosphate (manufactured by Daihachi Chemical Co., Ltd., TMCPP) Thinning agent: 5 parts by weight of propylene carbonate (manufactured by Arco Chemical Co., Ltd., PC1000)
(Example)
After mixing the polyol component and the polyisocyanate component using the apparatus shown in FIG. 1 with the above-described composition, spray foaming was performed on a plywood having a thickness of 12 mm and a slate plate having a thickness of 6 mm using a Model FF1600 foaming machine manufactured by Gasmer Admiral. Thus, a rigid polyurethane foam was obtained. At this time, the temperature and pressure of the polyol component and the polyisocyanate component were 50 ° C. and 7 Mpa.
Further, water was stored in the water storage tank 15, and the pipe was mixed with the polyol component being transferred via the pipe 17. As a result, it was possible to obtain a foam having a closed cell ratio of 91.2% and a moisture permeability of 195 ng / (m2 · s · Pa) and excellent heat insulation.
(Comparative example)
In the comparative example, the whole amount of water was previously mixed into the tank 1 of the polyol component and used after two weeks or more. Therefore, in the comparative example, the water storage tank 15 and the metering pump 16 were not used.
Stock solutions of the same formulation as in the examples were used in the same foaming machine. As a result, the reaction was slow, and when observed after 24 hours, shrinkage occurred, and a desired foam could not be obtained.
[0019]
【The invention's effect】
According to the production method of the present invention, since the premix stability of the polyol component can be improved, a rigid polyurethane foam with a stable water formulation can be obtained even with a polyurethane raw material stored for a long period of time, and a heat insulating property can be obtained. Is also excellent.
[Brief description of the drawings]
FIG. 1 is a view showing one embodiment of an apparatus for producing a rigid polyurethane foam.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Polyisocyanate component 2 Polyisocyanate component tank 3 Pump 4 Pipe 5 Mixing head 9 Heating hose 10 Heater 11 Polyol component 12 Polyol component tank 13 Pipe 14 Metering pump 15 Water storage tank 16 Metering pump 17 Pipe 18 Heater 19 Heating hose

Claims (2)

A method for producing a rigid polyurethane foam, wherein a polyol component containing at least a polyester-based polyol and a polyisocyanate component are mixed by a mixing head and spray-foamed,
A method for producing a rigid polyurethane foam, comprising mixing water as a foaming agent into a polyol component in a flow path of the polyol component leading to a mixing head. The method for producing a rigid polyurethane foam according to claim 1, wherein a static mixer is provided in a flow passage of the polyol component reaching the mixing head.

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