JPH04239516A - Production of rigid polyurethane foam - Google Patents

Abstract

PURPOSE:To provide a production method for obtaining a rigid polyurethane foam excellent in physical properties without using specific fluorocarbons as a blowing agent at all. CONSTITUTION:At least a polyol is reacted with a polyisocyanate and expanded to produce a rigid polyurethane foam. In the process, the polyol is a mixed polyol containing 30-60wt.% polymer polyol based on a polyester polyol and the average hydroxyl value of the whole polyol is within the range of 350-450(mg KOH/g). Only water is used as a blowing agent to produce the objective rigid polyurethane foam.

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 rigid polyurethane foam.

0002

[Prior Art] Rigid polyurethane foam has excellent heat insulation performance, lightweight structure, etc., and is therefore used as a heat insulating material.
It is widely used for building materials, structural materials, etc. Conventionally,
A method for manufacturing this rigid polyurethane foam is usually a method in which polyol and polyisocyanate are subjected to a foaming reaction by adding additives such as catalysts and surfactants, and foaming agents such as Freon CFC-11 and CFC-12. The rigid urethane foam thus produced has high heat insulation performance because the specific fluorocarbon used as a foaming agent is encapsulated in the closed cell structure. However, in recent years, these chlorofluorocarbon gases have threatened to destroy the earth's ozone layer, and in order to protect the global environment, efforts have been made to
The Montreal Protocol was adopted in 1987, with the aim of completely eliminating specified fluorocarbons by the end of the year. Therefore, in the production of rigid polyurethane foam, these specific fluorocarbons will no longer be usable in the near future, so there is a need for a new method for producing rigid polyurethane foam that does not use fluorocarbons. Conventionally, a method for manufacturing rigid polyurethane foam has been known in which foaming is performed using a combination of carbon dioxide gas generated by chemically reacting water with isocyanate and some specific fluorocarbons, but it is possible to produce rigid polyurethane foam without using fluorocarbons at all. In recent years, a method of manufacturing using only water as a blowing agent has been attracting attention.

0003

[Problems to be Solved by the Invention] However, the manufacturing method using only water as a blowing agent without using any specified fluorocarbons cannot sufficiently cool the reaction heat caused by the chemical reaction between water and isocyanate. There was a problem that problems such as cracks and scorches were likely to occur. This problem is particularly likely to occur in low-density foams having a density of 40 kg/m<3> or less, and it has been difficult to obtain rigid polyurethane foams that can be used practically. In addition, when only water is used as a foaming agent, the molding shrinkage of the foam increases because carbon dioxide dissipates from the inside of the bubbles to the outside faster than with fluorocarbons, so it is necessary to form a foam by laminating a face material on the surface of the foam. In the case of laminates, there are problems such as loss of surface smoothness and reduced adhesion between the foam and the facing material. Furthermore, when specific CFCs are not used, the viscosity of the resin during production is high, and the composition tends to be mixed and stirred poorly, resulting in uneven cell structure, resulting in a decrease in heat insulation performance. The present invention aims to solve the above-mentioned drawbacks of the prior art, and aims to provide a manufacturing method that makes it possible to obtain rigid polyurethane foam with excellent physical properties without using any specified fluorocarbons as a blowing agent. It is something.

0004

[Means for Solving the Problems] The present invention provides a method for producing rigid polyurethane foam by reacting and foaming at least a polyol and a polyisocyanate, in which the polyol contains 30 to 60% by weight of a polymer polyol based on a polyester polyol. It is a polyol, and the average hydroxyl value of the entire polyol is 350 to 450 (m
gKOH/g ), and is a method for producing rigid polyurethane foam, characterized in that it is produced using only water as a foaming material.

[0005] The polyol used in the present invention uses a polymer polyol based on polyester polyol in an amount of 30 to 60% by weight based on the total polyol component. It is obtained by graft polymerizing a polybyrni filler to a phthalate ester polyol obtained by an esterification reaction with a diol such as ethylene glycol or butylene glycol. Polyvinyl fillers include acrylonitrile, styrene,
It is made of a vinyl compound such as a vinyl monomer such as methyl methacrylate, and usually acrylonitrile, styrene alone or a mixture thereof is used. It is preferable to use the polyvinyl filler in an amount of 25% by weight or less based on the polymer polyol since there is no risk of separation of the polyol.

Generally, polyester polyols have a low hydroxyl value, low viscosity, and excellent heat resistance, making them suitable for foaming using only water. Stability decreases and shrinkage increases at room temperature. Therefore, by graft polymerizing the polyvinyl filler as described above, dimensional stability can be ensured and shrinkage at room temperature can be prevented. Further, if the polyvinyl filler is used in an amount of 25% by weight or less, there is no possibility that the polyol will separate. If the amount of polymer polyol used is less than 30% by weight of the total polyol, the heat resistance will be poor and the foam will develop cracks and scorches. If it exceeds 60% by weight, the dimensional stability of the foam at high temperatures will deteriorate.

[0007] Polyols other than polymer polyols to be used in the present invention include those having an average hydroxyl value in the range of 350 to 450 (mgKOH/g).
Although not particularly limited, it is preferred to use polyether polyols. Such a polyether polyol is a polyol obtained by adding an alkylene oxide such as ethylene oxide or propylene oxide to 40 to 70% by weight of sorbitol, pentaerythritol, ethylenediamine, sucrose, etc. in the polyether polyol. This polyether polyol preferably has a viscosity of 3000 (cps/25°C) or less in order to lower the resin viscosity. The average hydroxyl value of all polyols is 450 (mgKOH/g
) or more, the temperature inside the foam will be 170~2
The temperature rises to over 00°C, causing cracks and scorches in the foam. Also, the average hydroxyl value is 350 (
mgKOH/g ) or less, no cracks or scorch will occur, but shrinkage will increase and the dimensional stability of the resulting foam will be greatly reduced.

The amount of water added as a blowing agent is preferably 4 parts by weight or more and 7 parts by weight or less based on 100 parts by weight of the polyol because a foam density of 40 to 25 kg/m3 can be obtained. Foam density is 40-25K
In the range of g/m3, a foam having a fine cell structure can be obtained without deteriorating the heat insulation performance. If the amount of water used is less than 4 parts by weight per 100 parts by weight of polyol, the foam density will be 40 kg/m3 or more,
If the internal temperature of the foam rises too much, cracks are likely to occur, and if the amount exceeds 7 parts by weight, the foam density will decrease to 25 kg/kg.
m3 or less, mechanical strength, dimensional stability, etc. decrease, and when a laminate is made using a face material, surface smoothness decreases, which is not preferable.

[0009] As the polyisocyanate, aromatic polyisocyanates used in the production of conventional urethane foams can be used. Examples of aromatic polyisocyanates include tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate and mixtures thereof, diphenylmethane 4,4'-diisocyanate, and 3-methyldiphenylmethane 4,4'-diisocyanate.

[0010] The additive is preferably one that lowers the viscosity of the resin, such as trichloroethyl phosphate (TCEP), trichloropropyl phosphate (TCPP), dimethyl methyl phosphate (DMMP), etc., which are generally used in urethane foam. flame retardants, propylene carbonate, etc. can be used.

[0011] As the surfactant, silicone surfactants can be used, and as catalysts, amines, organometallic compounds, etc. that are commonly used in this type of rigid urethane foam can be used.

In the manufacturing method of the present invention, the method is not particularly limited as long as the above-mentioned raw materials are used for foaming, and any conventional method for manufacturing this type of foam can be used. That is, a continuous method such as a double conveyor method, a discontinuous method such as multilayer injection, injection injection, and in-situ foaming can be used as a method for producing normally rigid urethane foam. Furthermore, when foaming is performed using a double conveyor device, even a laminate in which a face material is laminated on the surface of the foam can be obtained with excellent surface smoothness and a good appearance. The face material used in the present invention can be either a hard face material or a soft face material, similar to general rigid urethane foam. The rigid polyurethane foam produced by the production method of the present invention can be suitably used for applications such as building insulation materials.

[0013]

[Examples] The present invention will be described in more detail below with reference to specific examples. Weigh the polymer polyol, polyol and foam stabilizer, additives, catalyst, water and crude MDI in the proportions shown in Table 1 in a 1 liter polyethylene beaker,
Small mixer (rotation speed 3000-3500 rpm)
After stirring vigorously for 5 to 7 seconds, the mixture was foamed in a 30 mm thick aluminum mold measuring 500 mm by 500 mm and heated to 30 to 40 DEG C. to obtain a rigid polyurethane foam. The obtained rigid polyurethane foam was demolded 10 minutes after the start of the reaction, and after curing for 3 days, it was tested for foam density, compressive strength, thermal conductivity, dimensional stability, smoothness, etc. The test results are shown in Tables 1-2. Examples 1 to 5 Good foams were obtained in which the proportion of the polymer polyol was in the range of 30 to 60 parts by weight. Example 6 All polyols with an average hydroxyl value raised to 450 were used, and a good foam was obtained. Examples 7 to 10 Foams were obtained by varying the amount of water added in Example 2 from 3 to 7.5 parts by weight based on 100 parts by weight of polyol. When the amount of water used was in the range of 4 to 7 parts by weight, the resulting foam had a foam density in the range of 25 to 40 kg/m<3>, which was good (Examples 7 and 8). In addition, when the water content is outside the range of 4 to 7 parts by weight, the foam density is 25 to 4 parts by weight.
It was outside the range of 0 Kg/m3, and a foam with slightly lower heat insulation performance than Examples 7 and 8 was obtained (Example 9).
, 10).

Next, for comparison, tests were conducted in the same manner as in the examples using the compositions shown in Table 3. Comparative Example 1 Foaming was performed using only a general polyester polyol without using a polymer polyol, but the resulting foam shrunk at room temperature. Comparative Examples 2 and 3 The amount of polymer polyol used was outside the range of 30 to 60 parts by weight. The resulting foam exhibited scorch formation and also had poor dimensional stability at high temperatures. Comparative Example 4 A polyol having a total hydroxyl value lower than 350 was used for foaming. The obtained foam had a large shrinkage at high temperatures, and the surface smoothness of the laminate was poor. Comparative Example 5 A polyol having a total hydroxyl value of over 450 was used for foaming. Cracks were observed in the obtained foam. Comparative Example 6 Foaming was carried out using only a polymer polyol as the polyol. The resulting foam shrunk at room temperature, making it impossible to form a panel.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

In Tables 1 to 3, the amounts are shown in parts by weight. Moreover, the following polyols A to J, foam stabilizers, catalysts, additives, and crude MDI were used. *1: Polymer polyol A A hydroxyl value of 250 made by graft polymerizing 18% by weight of polyvinyl filler with acrylonitrile/styrene ratio of 2/1 to a polyester polyol based on phthalic anhydride.
It had a viscosity of 3000 (cps/25°C). *2: Polymer polyol B A polyester polyol based on dimethyl terephthalic acid that is graft-polymerized with 25% by weight of polyvinyl filler with acrylonitrile/styrene ratio of 2/1, hydroxyl value 260 (mgKOH/g), viscosity 2200 (cps)
/25°C). *3: Polyol C A polyether polyol with a hydroxyl value of 400 (mgKOH/g) and a viscosity of 1800 (cps/25°C) obtained by adding propylene oxide to pentaerythritol. *4: Polyol D: Hydroxyl value 750 (mgKOH/g), viscosity 45, obtained by adding propylene oxide to ethylene diamine.
000 (cps/25°C) polyether polyol. *5: Polyol E A hydroxyl value of 330 (mgKO) obtained by adding ethylene oxide and propylene oxide to a Mannich condensate.
H/g) and a viscosity of 3000 (cps/25°C). *6: Polyol F A hydroxyl value of 440 (mgKO) obtained by adding ethylene oxide and propylene oxide to a Mannich condensate.
H/g) and a viscosity of 2000 (cps/25°C). *7: Polyol G Hydroxyl value 450 (mgKO) obtained by adding ethylene oxide and propylene oxide to ethylenediamine
Polyether polyol with a viscosity of 1200 (cps/25°C). *8: Polyol H hydroxyl value 500 (mgKOH/g) obtained by adding propylene oxide to sucrose aromatic amine,
Polyether polyol with a viscosity of 1300 (cps/25°C). *9: Polyol I obtained by adding propylene oxide to Sucrose, hydroxyl value 480 (mgKOH/g), viscosity 1200
0 (cps/25°C) polyether polyol. *10: Polyol J Hydroxyl value 315 (mgKOH/g) obtained by transesterification of phthalic anhydride and diethylene glycol
, a polyester polyol with a viscosity of 2000 (cps/25°C). *11: Foam stabilizer SH193 (manufactured by Toray Silicone) *12: Additive trichloroethyl phosphate *13: Catalyst Polycat 42 (manufactured by San-Apro) *14: Crude MDI isocyanate index = 150 *15: Resin viscosity by B-type viscometer measurement. *16: Foam density and compressive strength measured according to JISA951. *17: Measured according to thermal conductivity JISA1412. *18: Measured in accordance with dimensional stability ASTM D2126. *19: Smoothness of the laminate With the kraft facing material attached, the surface unevenness was visually observed and evaluated in three grades: ○, △, and ×.

As explained above, the present invention provides a mixed polyol in which the polyol contains 30 to 60% by weight of a polymer polyol based on a polyester polyol, and the average hydroxyl value of the entire polyol is 350 to 45.
0mgKOH/g, and by adopting a manufacturing method that uses only water as the foaming material, it is possible to manufacture rigid urethane foam without using any conventional CFC gas, which is said to destroy the ozone layer. can be,
Environmentally safe manufacturing can be performed. Further, the foam obtained by the production method of the present invention has a fine cell structure and has excellent heat insulation properties compared to conventional foam using only water as a blowing agent. Furthermore, the obtained foam has excellent surface smoothness, and even when face materials are laminated, there is no risk that the smoothness of the face materials will decrease or the face materials will peel off. In addition, it has various effects such as the ability to obtain a density equivalent to that of conventional urethane foam using fluorocarbons.

Claims (1)

[Claims] 1. A method for producing rigid polyurethane foam by reaction foaming at least a polyol and a polyisocyanate, wherein the polyol is a mixed polyol containing 30 to 60% by weight of a polymer polyol based on a polyester polyol, and A method for producing a rigid polyurethane foam, which has an average hydroxyl value in the range of 350 to 450 mgKOH/g and is produced using only water as a foaming material.