JPH07157529A - Water-expandable rigid polyurethane foam having open cell and its production - Google Patents

Abstract

PURPOSE:To obtain the subject polyurethane foam excellent in mechanical strength and dimensional stability, useful as e.g. a thermal insulation for refrigerators or motor vehicles, from an organic polyisocyanate, specific polyol, catalyst and auxiliary, using specified amount of water as a foaming agent. CONSTITUTION:This polyurethane foam is obtained from (A) an organic polyisocyanate, (B) a polyol as a mixture of 1-20 pts.wt. of diethanolamine and 80-99 pts.wt. of a polyether polyol having 20-350mgKOH/g average OH value, (C) a catalyst such as trimethylaminoethyl piperazine, (D) 0.5-10 pts.wt., based on 100 pts.wt. of the component B, of water as a defoaming agent, and (E) an auxiliary such as a foam stabilizer.

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 having open cells and a method for producing the same, and is expected to be suitably used as a heat insulating material or heat insulating structural material for refrigerators, freezers, heat insulating panels, ships, vehicles and the like. It is a thing.

[0002]

2. Description of the Related Art Rigid polyurethane foam generally has a closed cell structure and contains gas of chlorofluorocarbons, carbon dioxide gas and the like in the cells. Because of its excellent heat insulation performance, low-temperature dimensional stability, and workability, it is widely used as a heat insulating material for refrigerators, freezers, building materials, etc., or as a lightweight structural material. However, under a high temperature condition of, for example, 70 ° C. or more, or a condition in which the temperature changes drastically, the balance between the gas pressure in the bubbles and the strength of the structure of the polyurethane foam is disturbed, and dimensional changes occur, so that the range of use is restricted.

In order to solve the above problems in the closed cell rigid polyurethane foam, a rigid polyurethane foam mainly having an open cell structure, which is obtained by using a cell opener during the production of the rigid polyurethane foam, has been proposed. There is. The rigid polyurethane foam having open cells can be sufficiently used even under the severe conditions as described above. Liquid paraffin, polybutene and the like have been conventionally known as such a cell communicating agent (Japanese Patent Nos. 527024, 531657, etc.).

[0004]

In recent years, chlorofluorocarbons have been regulated to protect the ozone layer of the earth. This regulation target also includes R-11 which has been used as a foaming agent for rigid polyurethane foams. As one of the alternative blowing agents for R-11, it has been proposed to use only water as the blowing agent. Water is a reactive blowing agent that reacts with organic polyisocyanates to release carbon dioxide and form urea bonds. Rigid polyurethane foam using water as a foaming agent has problems such as brittleness, insufficient strength, deterioration of adhesiveness, deterioration of moldability, etc., as compared with the case of using conventional chlorofluorocarbons as a foaming agent. To do.

Even in rigid polyurethane foams having open cells, it is necessary to solve the above problems in order to use water as a blowing agent to replace chlorofluorocarbons. Further, since the conventional air bubble communicating agent has poor compatibility with polyol, when mixed with a polyol, a catalyst, a foaming agent, etc., the mixed solution easily causes layer separation during storage, and quality control is performed. It is difficult to say that it is a sufficient means for cell communication because it is difficult and the manufactured rigid polyurethane foam becomes non-uniform and cell roughening easily occurs.

[0006]

[Means for Solving the Problems] The inventors of the present invention have achieved the present invention as a result of diligent investigations using water as a foaming agent in order to sufficiently connect the cells of a rigid polyurethane foam. That is, the present invention provides a rigid polyurethane foam produced from (1) an organic polyisocyanate, a polyol, a catalyst, a foaming agent, a foam stabilizer, and other auxiliaries, and 1 to 20 parts by weight of diethanolamine as a polyol, and an average. A mixture with 80 to 99 parts by weight of a polyether polyol having a hydroxyl value of 200 to 350 mgKOH / g is used, and 0.5 to 10 parts by weight of water is used as a foaming agent per 100 parts by weight of the polyol. Water-foamed rigid polyurethane foam with open cells,
(2) In the method for producing a rigid polyurethane foam from an organic polyisocyanate, a polyol, a catalyst, a foaming agent, a foam stabilizer, and other auxiliary agents, as a polyol,
1 to 20 parts by weight of diethanolamine and an average hydroxyl value of 2
An open cell characterized by using a mixture with 80-99 parts by weight of polyether polyol of 0-350 mg KOH / g and using 0.5-10 parts by weight of water per 100 parts by weight of polyol as a blowing agent. A method for producing a water-foamed rigid polyurethane foam having:

If the amount of diethanolamine in the polyol is less than 1 part by weight per 100 parts by weight of the polyol, there is no effect, and if it exceeds 20 parts by weight, the dimensional stability deteriorates with an increase in the closed cell ratio, which is not practical. As the polyether polyol having an average hydroxyl value of 200 to 350 mgKOH / g, a polyfunctional polyether polyol usually used for producing a rigid polyurethane foam can be preferably used. If the average hydroxyl value is less than 200 mgKOH / g, the compressive strength will be reduced, and if it exceeds 350 mgKOH / g, the closed cell ratio will not be sufficiently reduced, and neither is practical.

Known organic polyisocyanates can be used. The most common are toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI). TDI is a mixture of isomers, that is, 2,4-body 100% product, 2,4-body / 2,6
-Body = 80/20, 65/35 (weight ratio) and the like, as well as so-called crude TDI containing a polyfunctional tar known under the trade name Mitsui Cosmonate TRC and the like can be used. Further, as the MDI, in addition to a pure product containing 4,4′-diphenylmethane diisocyanate as a main component,
A so-called polymeric MDI such as Mitsui Cosmonate M-200 under the trade name containing polyhedra having three or more nuclei can be used. Among them, MDI, in particular, so-called polymeric MDI of Mitsui Cosmonate M-200 containing a polyhedron having three or more nuclear bodies can be particularly preferably used. The equivalent ratio of the isocyanate group and active hydrogen is NCO / H (active hydrogen) =
0.60 to 5.00 is preferable.

As the catalyst, for example, amine-based urethane-forming catalysts such as trimethylaminoethylpiperazine, triethylamine, tripropylamine, N-methylmorpholine, N-ethylmorpholine, triethylenediamine and tetramethylhexamethylenediamine are particularly preferable. Needless to say, urethanization catalysts such as organic metal type and organic acid type can also be used. These catalysts can be used alone or as a mixture, and the amount thereof is appropriately 0.0001 to 10.0 parts by weight per 100 parts by weight of the compound having active hydrogen.

As the foam stabilizer, a conventionally known organosilicon surfactant is used. For example, L- made by Nippon Unicar Co., Ltd.
5420, L-5340, SZ-1645, SZ-16
27, SZ-1923, Shin-Etsu Chemical Co., Ltd. F-34
3, F-345, F-347, F-348, F-350
S or the like is suitable. The amount of these foam stabilizers used is such that the total amount of the compound having active hydrogen and the organic polyisocyanate is 10
0.1 to 10 parts by weight is suitable per 0 part by weight. In addition, flame retardants, plasticizers, stabilizers, colorants and the like can be added as required.

[0011]

EXAMPLES The present invention will be described below with reference to examples. The raw materials used in Examples and Comparative Examples are as follows. Cosmonate M-200: Mitsui Toatsu Chemical Co., Ltd. polymeric MDI total NCO 31.3% Polyol A: sucrose / water (weight ratio 98/2) with a hydroxyl value of 410 mg KOH / g
Polyether polyol. Polyol B: Polyether polyol having a hydroxyl value of 230 mgKOH / g obtained by adding propylene oxide to glycerin. Polyol C: Polyether polyol having a hydroxyl value of 168 mgKOH / g obtained by adding propylene oxide to glycerin. Polyol D: Polyether polyol having a hydroxyl value of 56 mgKOH / g, which is obtained by adding propylene oxide to glycerin. Polyol E: Polyether polyol having a hydroxyl value of 33 mgKOH / g obtained by adding propylene oxide to glycerin. Foam stabilizer: Nippon Unicar's product SZ-1923 Catalyst: Active Material Chemical's product Minico L-1020

Predetermined amounts of the polyol, water, foam stabilizer and catalyst shown in Tables 1 and 2 were weighed and kept at 25 ° C. 25 to this
A predetermined amount of organic polyisocyanate (Cosmonate M-200) kept at ℃ was added, and the mixture was mixed at high speed for 5 seconds.
Aluminum mold adjusted to 0 ° C (thickness 20 mm x width 30
(0 mm × length 450 mm), and after 5 minutes, the mold was removed. The equivalent ratio of organic polyisocyanate to total active hydrogen was NCO / H = 0.85. Various characteristic values of the obtained rigid polyurethane foam are shown in Tables 1 and 2. In addition,
The numbers in the table represent parts by weight unless otherwise specified.

The conditions for measuring various characteristic values of the rigid polyurethane foam are as follows. Closed cell ratio: According to ASTM D-2856. Density: The density of the core of rigid polyurethane foam. Dimensional stability: Volume change rate of the rigid polyurethane foam core part left standing for 24 hours in a low temperature bath at -30 ° C and a constant temperature bath at 70 ° C and 95% relative humidity. Compressive strength: Compressive strength in the thickness direction.

[0014]

[Table 1]

[0015]

[Table 2]

From Examples 1 to 5 and Comparative Examples 1 and 2 in Table 1, when the amount of diethanolamine was 1 to 20 parts by weight per 100 parts by weight of polyol, dimensional stability and compressive strength were not deteriorated. A great effect is recognized in the reduction of the closed cell rate. From Examples 6 and 7 and Comparative Examples 3 and 4 in Table 2, it is understood that unless the average hydroxyl value of the polyol other than diethanolamine is 200 to 350 mgKOH / g, the compressive strength is lowered or the dimensional stability is deteriorated.

[0017]

INDUSTRIAL APPLICABILITY The present invention uses water as a foaming agent to provide an open-celled rigid polyurethane foam having sufficient dimensional stability and strength.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Minoru Watanabe 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (2)

[Claims] 1. An organic polyisocyanate, a polyol,
In a rigid polyurethane foam produced from a catalyst, a foaming agent, a foam stabilizer, and other auxiliary agents, as a polyol, 1 to 20 parts by weight of diethanolamine and 80 to 99 parts by weight of a polyether polyol having an average hydroxyl value of 200 to 350 mgKOH / g. Water-foamed rigid polyurethane foam with open cells, characterized in that 0.5 to 10 parts by weight of water is used per 100 parts by weight of polyol as a blowing agent. 2. An organic polyisocyanate, a polyol,
In the method for producing a rigid polyurethane foam from a catalyst, a foaming agent, a foam stabilizer, and other auxiliary agents, as a polyol, 1 to 20 parts by weight of diethanolamine and a polyether polyol 80 to 99 having an average hydroxyl value of 200 to 350 mgKOH / g. 0.5 to 1 per 100 parts by weight of polyol as a blowing agent, using a mixture with 1 part by weight.
A process for producing a water-foamed rigid polyurethane foam having open cells, characterized in that 0 part by weight of water is used.