JPH0525243A - Production of rigid polyirethane foam - Google Patents

Abstract

PURPOSE:To provide a rigid polyurethane foam having excellent properties even by using water as a blowing agent. CONSTITUTION:A process for producing a rigid polyurethane foam by reacting a polyisocyanate component with a polyol component by using water as a blowing agent in the presence of a catalyst, wherein the polyol component contains 15-40wt.% modified polyether polyol of a hydroxyl value of 350-500 and has an average hydroxyl value of 400-500.

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 a rigid polyurethane foam which is used as a heat insulating material for buildings such as ceilings, floors and walls and does not require the use of CFCs as a foaming agent.

[0002]

2. Description of the Related Art Rigid polyurethane foam is produced by reacting a polyisocyanate component and a polyol component in the presence of a foaming agent, a foam stabilizer, a catalyst, and the like, and particularly trifluoromonofluoromethane as a foaming agent. Excellent heat insulation performance is maintained by using CFCs. However, the Montreal Protocol came into effect in 1989, and by the end of this century, the use of specific fluorocarbons including trifluoromonofluoromethane was completely abolished. Therefore, in recent years, using water as a foaming agent to reduce freon, a method for producing a rigid polyurethane foam has been proposed, but when water is used as a foaming agent, thermal conductivity and dimensional stability deteriorate, At present, a good foam has not been practically obtained.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art, and an object thereof is to provide a rigid polyurethane foam having excellent physical properties even when water is used as a foaming agent.

[0004]

According to the present invention, when a rigid polyurethane foam is produced by reacting a polyisocyanate component and a polyol component with water as a blowing agent in the presence of a catalyst, the polyol component has a hydroxyl value of 35.
Modified polyether polyol of 0-500 15-40
% By weight, and the average hydroxyl value of all polyol components is 4
The present invention provides a method for producing a rigid polyurethane foam, which is characterized by using 100 to 500.

The polyol component used in the present invention contains 15 to 40% by weight of a modified polyether polyol having a hydroxyl value of 350 to 500, and the average hydroxyl value of all polyol components is 400 to 500. It has characteristics. Here, the modified polyether polyol is obtained in the form of an insoluble stable suspension or a stable solution by grafting a polyvinyl filler onto the polyether polyol. As the polyether polyol used at this time, trifunctional glycerin, trimethylolpropane, triethanolamine or the like is used as an initiator, and one kind or two or more kinds of ethylene oxide, propylene oxide, butylene oxide or the like is added. Examples include polyols. As the polyvinyl filler, acrylonitrile, styrene, alkyl (meth) acrylates such as methyl (meth) acrylate, vinyl-based monomers such as vinyl acetate and vinyl chloride are used alone or in combination. The content of the polyvinyl filler in the modified polyether polyol is 20% by weight or less, preferably 1%.
It is 0 to 20% by weight.

The hydroxyl value of the modified polyether polyol used in the present invention is 350 to 500. When the hydroxyl value is less than 350, the liquid is separated in the polyol component, and cracks are generated in the obtained foam. on the other hand,
When the hydroxyl value exceeds 500, the polyvinyl filler is precipitated and a stable polyol component cannot be obtained. The modified polyether polyol is used in an amount of 15 to 40% by weight, preferably 20 to 35% by weight, based on the total polyol components. If it exceeds, the adhesiveness to the face material and the thermal conductivity deteriorate.

As the polyol used in all the polyol components, glycerin, sorbitol, ethylenediamine, pentaerythritol, methylglucoside, tolylenediamine, Mannich, sucrose, etc. are used as an initiator, and ethylene oxide, propylene oxide, butylene oxide are used. Such as polyether polyol obtained by adding one or two or more of the above, waste PET,
Aromatic polyester polyols based on DMT process residues, phthalic anhydride and the like. The average hydroxyl value of all the polyol components including the above modified polyether polyol and general polyol is 400 to
500. If the average hydroxyl value is less than 400, the resulting foam will shrink at room temperature within 1 to 2 weeks, while if it exceeds 500, scorch and cracks will occur in the resulting foam.

As the polyisocyanate component used in the present invention, generally used aromatic polyisocyanate, alicyclic polyisocyanate, or aliphatic polyisocyanate can be adopted. Specific examples of the polyisocyanate component include tolylene 2,4-diisocyanate, tolylene 2,6-diisocyanate and mixtures thereof, diphenylmethane-4,4'-diisocyanate, 3-methyldiphenylmethane-4,4'-diisocyanate and these. Any of the compositions normally used in the production of rigid polyurethane foams such as hexamethylene diisocyanate can be used. The amount of polyisocyanate component used is 100 to 100 in terms of equivalent ratio of isocyanate group to hydroxyl group (NCO / OH index).
Used at a rate of 120.

The present invention is characterized in that water is used as a foaming agent. This water reacts with a polyisocyanate component to generate carbon dioxide gas, and this gas foams polyurethane in the production process to form foam. Are formed. The amount of water used is 8 parts by weight or less, preferably 5 to 8 parts by weight, based on 100 parts by weight of the polyol component. If the amount of water used exceeds 8 parts by weight, the resulting foam will shrink at room temperature and cannot be put to practical use.

Examples of the catalyst used in the polyurethane reaction include tertiary amines such as dimethylethanolamine, triethylenediamine, tetramethylpropanediamine, tetramethylhexamethylenediamine, dimethylcyclohexylamine, stannas octate,
Examples thereof include metal catalysts such as potassium octylate and dibutyltin dilaurate. These catalysts are usually used in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the polyol component.

In the production of the rigid polyurethane foam of the present invention, other additives such as a foam stabilizer, a viscosity modifier and a flame retardant may be added. Among these, the silicone foam stabilizer is preferable as the foam stabilizer, and for example, SH-193, BY-10-5 manufactured by Toray Dow Corning Co., Ltd.
40, Nippon Unicar Co., Ltd., L-5420, L-53
20, L-5340, SZ1605, Shin-Etsu Silicone Co., Ltd., F305, F341 and the like. The foam stabilizer is usually 100 parts by weight of the polyol component,
About 0.1 to 5 parts by weight is used.

The additives used in the present invention are added for the purpose of lowering the viscosity of the polyol component and keeping the reaction ratio balance with the polyisocyanate component. Examples of the low-viscosity additive satisfying these conditions include flame retardants such as chlorinated paraffin, trischloroethyl phosphate and trischloropropyl phosphate, surfactants such as nonylphenol ether, and viscosity reducing agents such as propylene carbonate. .. These additives are usually used in an amount of about 10 to 50 parts by weight based on 100 parts by weight of the polyol component so as not to deteriorate the physical properties of the obtained foam.

As a concrete means for producing the rigid polyurethane foam of the present invention from the above raw materials, any device can be used as long as it can uniformly mix the raw materials. For example, a small experimental mixer or a foaming machine can be used. The rigid polyurethane foam of the present invention can be easily obtained by uniformly and continuously mixing the raw materials.

[0014]

EXAMPLES The present invention will be described in more detail below with reference to examples. In the examples, parts and% are based on weight unless otherwise specified. In addition, in the examples, the evaluation of the hydroxyl value and the physical properties of the polyurethane foam are values measured as follows. Mg of potassium hydroxide corresponding to OH group in 1 g of hydroxyl value polyol Compressive strength Measured according to JIS A9514 Measured thermal conductivity according to JIS A9514 After making an adhesive panel with a face material , put a 10 mm width step Dimensional stability measured with a spring balance Measured in accordance with ASTM D2126 Reference Example (Preparation of Raw Materials) Table 1 shows the preparation of various raw materials.

[0015]

[Table 1]

Examples 1 to 5 and Comparative Examples 1 to 6 After blending a polyol component, an additive, a foam stabilizer, a catalyst, water and the like in the formulation shown in Table 2, NCO / OH (index) = 105. A polyisocyanate component was added thereto so as to be mixed with stirring, and foamed in a box of 200 × 200 × 200 mm to obtain a rigid polyurethane foam. After leaving this foam for 2 days, it was cut into a predetermined size and the foam density, compressive strength and dimensional stability were measured.
In addition, a panel was prepared by foaming the mixed solution in a 25 mm thick × 300 × 300 mm mold, and the thermal conductivity and the adhesiveness to the paper surface material were evaluated. The results are also shown in Table 2.

[0017]

[Table 2]

[0018]

The rigid polyurethane foam obtained by the production method of the present invention contains no freons as a foaming agent, retains the conventional thermal conductivity and is excellent in dimensional stability. It is useful as a new heat insulating material after the abolition of fluorocarbons.

[Procedure amendment]

[Submission date] September 2, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art Rigid polyurethane foams are produced by reacting a polyisocyanate component and a polyol component in the presence of a foaming agent, a foam stabilizer, a catalyst and the like, and particularly, as a foaming agent such as trichloromonofluoromethane. Excellent heat insulation performance is maintained by using CFCs. However, the Montreal Protocol came into effect in 1989, and by the end of this century, the use of specific CFCs including trichloromonofluoromethane was completely abolished. Therefore, in recent years, using water as a foaming agent to reduce freon, a method for producing a rigid polyurethane foam has been proposed, but when water is used as a foaming agent, thermal conductivity and dimensional stability deteriorate, At present, a good foam has not been practically obtained.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction content]

[0015]

[Table 1]

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

[0017]

[Table 2]

Claims (1)

Claims: 1. When a rigid polyurethane foam is produced by reacting a polyisocyanate component and a polyol component in the presence of a catalyst with water as a blowing agent, the polyol component has a hydroxyl value of 350 to 500. 15. A method for producing a rigid polyurethane foam, which comprises using the modified polyether polyol of 5 to 40% by weight and using an average hydroxyl value of all polyol components of 400 to 500.