JP3309335B2 - Method for producing rigid polyurethane foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rigid polyurethane foam and an isocyanurate-modified rigid polyurethane foam (hereinafter, simply referred to as a rigid polyurethane foam) mainly used as a heat insulating material or an airtight holding material, and a method for producing the same.

[0002]

2. Description of the Related Art Rigid polyurethane foam has excellent heat insulating properties, self-adhesiveness and airtightness, and is used as a heat insulating material for architectural structures such as houses and refrigerators, or refrigeration equipment such as vending machines and refrigerators. Widely used as. This rigid polyurethane foam is generally produced by mixing and stirring a polyhydroxy compound and a polyisocyanate compound together with a catalyst, a foaming agent, a foam stabilizer, and other auxiliaries, and physically or chemically occurring foaming and curing reactions. ing. As a foaming agent in this case, trichloromonofluoromethane (hereinafter, referred to as F-11) has been mainly used because of its low thermal conductivity and the advantage that its boiling point is around room temperature.

However, this F-11 has been shown to have a negative effect on the atmospheric environment due to the ozone layer depletion of the earth, and has been designated as a specified CFC as a regulated substance, and has been completely abolished in Japan. Chlorofluorocarbon (hereinafter abbreviated as CFC) represented by F-11 has a structure that does not contain a hydrogen atom in a molecule, and is therefore chemically stable, is decomposed for the first time in the stratosphere, and chlorine generated there is converted into an ozone layer. Is to be destroyed. Due to such problems, dichloromonocarbon, which is a hydrochlorofluorocarbon (hereinafter abbreviated as HCFC), which contains one or more hydrogen atoms in the molecule, is not as chemically stable as CFC, and thus has little influence on destruction of the ozone layer. Fluoromethane, dichloromonofluoromethane and the like have been used as alternative foaming agents, and these HCFCs, although weak, also destroy the ozone layer. For this reason, the practical application of a rigid polyurethane foam using a foaming agent that does not destroy the ozone layer at all is desired. However, as a technique studied so far, only water is used as a foaming agent, and water and a polyisocyanate compound are used. It is common to use carbon dioxide generated by the reaction with
On the other hand, in recent years, a technique using a hydrofluorocarbon compound (hereinafter abbreviated as HFC) that does not destroy the ozone layer has been proposed.

[0004]

However, in the former technique using only water as a foaming agent, although the ozone layer is not destroyed, the heat conductivity of carbon dioxide gas, which is a drawback when water is used as the foaming agent, is low. There is a problem that heat insulation and dimensional stability are inferior because the carbon dioxide gas is easily diffused into the atmosphere from the foam and replaced with air, and the adhesiveness is deteriorated. Promising candidates for a blowing agent that does not destroy the ozone layer include 1,1,1,1,3,3-pentafluoropropane (hereinafter abbreviated as HFC245fa) and the like, and techniques for application to hard urethane are being developed. But this HFC24
5fa (boiling point: 15 ° C.) has low solubility in polyols, and hardly dissolves in polyester polyols in particular, and it is difficult to premix as a polyol component at room temperature. In other words, there is a problem that foaming cannot be performed well and rigid polyurethane foam cannot be produced because of lack of stability during premixing, which is a necessary condition required for a foaming agent. The present invention has been made in view of the above circumstances, and uses a foaming agent having low solubility in polyol and lacking in premix stability, has excellent foaming stability, and is hard without destroying the ozone layer. A polyurethane foam and a method for producing the same.

[0005]

Means for Solving the Problems The present inventors mix a polyisocyanate component and a polyol component obtained by mixing a catalyst, a foaming agent, a foam stabilizer, and other auxiliaries with a mixing head to form an airless spray foam. In a method for producing a rigid polyurethane foam by forming a rigid polyurethane foam, a compound containing 1,1,1,1,3,3-pentafluoropropane is used as a foaming agent in a mixing head or in a conduit from another component to the mixing head. The present inventors have found that by directly introducing and mixing, it is possible to obtain a rigid polyurethane foam which is stably mixed and has little variation in quality, and has accomplished the present invention.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The gist of the present invention is to provide a rigid polyurethane foam in which a polyisocyanate component and a polyol component obtained by mixing a catalyst, a foaming agent, a foam stabilizer and other auxiliaries are mixed and foamed by a mixing head. The present invention relates to a rigid polyurethane foam and a method for producing the same, characterized in that a blowing agent containing HFC245fa is directly introduced into a mixing head or a conduit from other components to the mixing head and mixed in airless spray foaming.

In the present invention, as a method of stably mixing a foaming agent containing HFC245fa into a polyol component, a method of directly introducing and mixing into a mixing head of an airless spray foaming machine or a conduit from another component to the mixing head is used. It is not particularly limited. Conventionally, this mixing method has been used in a froth foaming method using a gaseous low-boiling Freon gas as a blowing agent at normal temperature as shown in JP-B-62-25430. However, F11 and HCFC141b whose boiling points are around room temperature are used. A premix method in which the mixture was previously mixed with the polyol component was possible and was a usual method. In the present invention, H having a boiling point near room temperature is used.
This is a method in which FC245fa (boiling point: about 15 ° C.) is directly introduced into a mixing head of an airless spray foaming machine or a conduit from other components to the mixing head and mixed.

The mixing amount of HFC245fa is arbitrarily determined depending on the density of the foam to be obtained. Usually, 5 to 30 with respect to the total weight of the polyol component and the isocyanate component.
%, Preferably 5 to 20% by weight. If the mixing amount is less than 5% by weight, the effect as a foaming agent is too small, and if it is more than 30% by weight, the vaporizing power is too strong, the foaming becomes unstable, and the bubbles are coarse and a good foam cannot be obtained.

On the other hand, those used in combination with these blowing agents in the mixing method include HCFC22 and HFC13.
Compounds that are gaseous at room temperature such as 4a and compounds that are liquid at room temperature such as HCFC141b and water can be used in combination of two or more. However, HCFC
Those which are liquid at room temperature, such as 141b or water, and which are stably dissolved even if previously mixed with a polyol component or the like can be premixed with the polyol component.

The polyol used in the present invention is obtained by a polycondensation reaction between a polybasic acid such as adipic acid, succinic acid, and phthalic acid and a hydroxy compound such as ethylene glycol and propylene glycol, or by ring-opening polymerization of lactones. Polyether polyols obtained by ring-opening addition polymerization of alkylene oxides such as ethylene oxide and propylene oxide to polyester polyols, glycerin, sucrose, ethylenediamine, tolylenediamine, etc., each alone or in combination of two or more They can be used in combination.

The polyisocyanate compound used in the present invention includes aromatic isocyanates such as diphenylmethane diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, aliphatic isocyanates such as hexamethylene diisocyanate and crude products thereof. Can be used. The polyisocyanate index based on the total amount of other active hydrogen-containing compounds such as polyol and water is 80 when producing a normal polyurethane foam.
In the case of producing an isocyanurate-modified rigid polyurethane foam, the range is preferably from 150 to 350.

The compound used as a catalyst in the present invention includes polyurethane compounds such as amine compounds such as triethylenediamine, tetramethylhexamethylenediamine and pentamethyldiethylenetriamine, and organometallic compounds such as dibutyltin dilaurate and stannas octoate. Can be used as they are. Also, trisdiaminopropylhexahydrotriazine,
Those used for isocyanate modification such as potassium acetate and potassium octylate can also be used. In the present invention, any other components other than those described above, for example, a flame retardant, a filler, and the like can be used as other auxiliary agents as long as the object of the present invention is not hindered.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Table 1 shows the formulations of Examples and Comparative Examples.

[Table 1]

The following raw materials were used in Table 1. Polyol A: Polyester polyol "PL-2001" manufactured by Toho Rikagaku Kogyo Co., Ltd. Polyol B: Polyether polyol "GR-10" manufactured by Takeda Pharmaceutical Co., Ltd. Flame retardant: Tris monochloropropyl phosphate manufactured by Stoffer Japan Co., Ltd. Filol PCF "Foam stabilizer: Silicone foam stabilizer" L-5420 "manufactured by Nippon Unicar Co., Ltd. Catalyst A: Kao Corporation Tetramethylhexamethylenediamine" Kaolyzer No1 "Catalyst B: Nippon Chemical Industry Co., Ltd. D of lead octylate
OP solution (lead concentration 17.1%) Catalyst C: Potassium 2-ethylhexylate "B-15G" manufactured by Nippon Chemical Industry Co., Ltd. Polyisocyanate: "Crude diphenylmethane diisocyanate" manufactured by Sumitomo Bayer Urethane Blowing agent: Daikin Industries, Ltd. HFC
-245fa "

[0015]

Examples 1 and 2 According to the formulation shown in Table 1, first, a formulation A (polyol component) 10 was prepared, and then a formulation B (polyisocyanate component) 11 and a blowing agent HF
Three components of C245fa12 were prepared. Next, as a high pressure spray foamer system of the airless mixing type, a gasmer FF unit 1600 (manufactured by Gasmer) was used, and as shown in FIG. 1, the mixed liquid A10 and the mixed liquid B11 were the main pump 3, the HFC245fa12 was the nitrogen gas 13 and the back pressure. Pumping from two subunit pumps 4 (foaming aid proportional pump manufactured by Gasmer Co., Ltd.)
m, 910 mm in width, and 5 mm in thickness were spray-foamed at room temperature of 25 to 30 ° C. The temperature of the liquid mixture in the foaming machine was set at 35 ° C., and the air pressure of the air pump was set at 5 kg / cm ² . The rigid polyurethane foam was laminated three times with a spray having a thickness of about 10 mm.

[0016]

Comparative Examples 1 and 2 Foaming was attempted by a method of premixing a foaming agent HFC245fa into a polyol component. As a result, in the method of premixing the foaming agent HFC245fa into the polyol component, foaming and bumping-like phenomena due to impact and separation of HFC245fa are observed in the polyol component stock solution. Cavitation occurred when the air pump on the side of the compounding liquid A contained sucked up the liquid, and foaming was impossible. On the other hand, HFC245fa
12 is mixed liquid A (polyol component) 10 and mixed liquid B (polyisocyanate component) 1 by subunit pump 4
In method 1, the rigid polyurethane foam could be molded stably without cavitation by the method of directly mixing as the third component.

[0017]

As described above, according to the method for producing a rigid polyurethane foam according to the present invention, a heat insulating material which does not destroy the ozone layer which is strongly demanded by society to protect the global environment is provided. A good rigid polyurethane foam that satisfies functions sufficiently can be obtained, and its industrial utility value is extremely high.

[0018]

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a manufacturing apparatus according to an embodiment of the present invention.

[Explanation of symbols]

1: Subunit 2: Mixer 3: Main pump 4: Subunit pump 5: Cylinder 6: Heater 7: Hose heater 8: Mixing head 9: Air 10: Compound liquid A (polyol component) 11: Compound liquid B (polyisocyanate Component) 12: HFC245fa 13: Nitrogen gas (back pressure about 15Kg / cm ² ) 14: Electromagnetic valve

Claims (1)

(57) [Claims] 1. A hard polyurethane which forms a hard polyurethane foam by mixing a polyisocyanate component and a polyol component obtained by mixing a catalyst, a foaming agent, a foam stabilizer, and other auxiliaries with a mixing head and airless spray foaming. In the method of manufacturing a foam,
A process for producing a rigid polyurethane foam, which comprises introducing a compound containing 1,1,3,3-pentafluoropropane as a foaming agent directly into a mixing head or a conduit from other components to the mixing head, and mixing the mixture.