JPH08193118A - Rigid polyurethane foam and production thereof - Google Patents

Abstract

PURPOSE: To produce a rigid polyurethane foam which has high strength and a high effective compression ratio and which, even when thin, has high impact- absorbing or impact-damping properties by using water as a foaming agent. CONSTITUTION: An alcohol ingredient comprising 55-95wt.% (exclusive of 55) polyoxyalkylene polyol having an average functionality of 2.5-6 and a hydroxyl value of 400-600mgKOH/g and a monohydric alcohol having a hydroxyl value of 400-1,800mgKOH/g is reacted with an aromatic polyisocyanate using water as a foaming agent in an amount of 2.5-5.5 pts.wt. per 100 pts.wt. the alcohol ingredient to obtain a rigid polyurethane foam. The alcohol ingredient may further contain a plyoxyalkylene polyol having an average functionality of 2-3.5 and a hydroxyl value of 25-60mgKOH/g and/or a polyol which is an alkylene oxide adduct of an organic polyamine.

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 suitable as an impact absorbing material, a structural material and the like and a method for producing the same.

[0002]

2. Description of the Related Art Rigid polyurethane foam is widely used as a heat insulating material, a structural material, a shock absorbing material, etc. because of its high moldability. The rigid polyurethane foam usually has closed cells in which a halogenated hydrocarbon such as trichlorofluoromethane or a gas such as carbon dioxide is enclosed. Further, since the gas has a low thermal conductivity, closed-cell rigid polyurethane foam has a high heat insulating property and is widely used as a heat insulating material.

On the other hand, a rigid polyurethane foam used as a shock absorbing material or a structural material does not require particularly high heat insulating properties, but is inexpensive and easy to handle halogenated hydrocarbons (for example, trichlorofluoromethane) are foamed. Used as an agent. However, in recent years, from the viewpoint of protecting the ozone layer, trichlorofluoromethane (R-11, CF
The use of halogenated hydrocarbons such as C-11) (hereinafter sometimes simply referred to as CFCs) is restricted. In particular,
In the use of foams that do not essentially require halogenated hydrocarbons such as shock absorbers and structural materials, it is required to refrain from using CFCs as much as possible from the viewpoint of environmental protection and economics. . That is, it is possible to use a foam having closed cells as the rigid polyurethane foam for the shock absorber, but since the closed cells contain gas as described above, the pressure (foaming pressure) acting on the mold during molding is increased. ) Is high, and a molding jig with high strength is required, and the dimensional accuracy of the molding form is likely to deteriorate. Thus, when heat insulation is not required, unlike rigid polyurethane foam as a shock absorber, it is not necessary to use CFCs to form a foam having closed cells.

Further, in recent years, as one of safety measures for automobiles, a shock absorbing material is being used to absorb a shock at the time of collision. This shock absorbing material is, for example, Japanese Patent Publication No.
As described in Japanese Patent Publication No. 4027 and Japanese Patent Publication No. 52-34678, it is a polyurethane foam having a large cell diameter and continuous cells.

Since high thermal insulation is not required for such an impact-absorbing open-cell rigid polyurethane foam, it is desirable not to use CFC as a foaming agent.
However, if chlorofluorocarbon is not used as a foaming agent, it is generally difficult to produce an open-cell rigid polyurethane foam, not only for a shock absorber.

With regard to rigid polyurethane foams having open cells, EP-A-0622388 describes the reaction of a specific polyol mixture or polyol / monoalcohol mixture with a polyisocyanate in the presence of water as a blowing agent. A method of making a rigid polyurethane having cells and suitable as a shock absorbing material is disclosed. In this method, the polyol mixture has an average number of functional groups of 2 to 3.5 and a hydroxyl value of 25 to 60 mgK.
OH / g of first polyoxyalkylene polyol 5-
55% by weight, average number of functional groups 3 to 5 and hydroxyl value 1
20-80% by weight of a second polyoxyalkylene polyol having 50 to 800 mgKOH / g and composed of an adduct of polyamine and alkylene oxide, and having an average number of functional groups of 2 to 6 and a hydroxyl value of 200 to 900 mgKOH.
/ G of third polyoxyalkylene polyol 0-60
A mixture with% by weight is used. Also, as a polyol / monoalcohol mixture, the first polyoxyalkylene polyol 5-55 wt%, the second polyoxyalkylene polyol 20-80 wt%,
Third polyoxyalkylene polyol 0-55% by weight
And a monoalcohol having a hydroxyl value of 400 to 1800 mg KOH / g is used.

However, the cells of the rigid polyurethane foam obtained by this method are open cells. Therefore, the gas inside the cell cannot be used for assistance, and the foam
The strength is greatly reduced with the decrease in the density. In the case of an open-cell foam, it is essentially difficult to satisfy the demands for low density and high strength.

Further, various properties are required for the shock absorbing material which absorbs and absorbs a shock which acts temporarily or suddenly. Above all, it is important that the foam has a high effective compression rate. FIG. 1 is a graph showing the relationship between compressive stress and compressibility when statically compressing a general rigid polyurethane foam. In FIG. 1, the line AB indicates the compressive strength (breaking strength), and the compressibility at point B corresponds to the effective compressibility. The energy absorption amount of the shock absorber is shown by the shaded portion in FIG. 1, but if it is necessary to form a space as large as possible (for example, a large migration space in an automobile), the thickness of the shock absorber should be reduced. It should be as thin as possible. In order to reduce the thickness of the shock absorbing material, not only the compressive strength but also the effective compressibility is required to be large. Further, from the viewpoint of energy saving, it is desired to reduce the weight by reducing the density of the impact absorbing material.

[0009]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a rigid polyurethane foam having high strength and effective compressibility.

Another object of the present invention is to provide a rigid polyurethane foam which has closed cells and has a high shock absorbing property or a high shock absorbing property even when the thickness is small.

Still another object of the present invention is to provide a rigid polyurethane foam which has a large mechanical strength even at a low density and is lightweight.

Another object of the present invention is to provide a method for easily producing a rigid polyurethane foam having the above-mentioned excellent properties by using water as a foaming agent.

Still another object of the present invention is to provide a shock absorber,
It is intended to provide a method capable of stably producing a rigid polyurethane foam suitable as a structural material or the like.

[0014]

Means for Solving the Problems As a result of intensive studies for achieving the above-mentioned object, the present inventors have found that a specific hydroxy compound is combined with an aromatic polyisocyanate in the presence of a specific amount of water as a foaming agent. It was found that when reacted, a rigid foam having closed cells and high compressive strength and effective compressibility was obtained, and the present invention was completed.

That is, according to the method of the present invention, (a1) the average number of functional groups is 2.5 to 6 and the hydroxyl value is 400 to 600 m.
gKOH / g of a polyoxyalkylene polyol and (a2) a hydroxyl value of 400 to 1800 mg KOH / g of a monoalcohol, and the content of the polyol (a1) is 5
More than 5% by weight and 95% by weight or less of (A) alcohol component and (B) aromatic polyisocyanate are added to water (C) 2 as a foaming agent with respect to 100 parts by weight of the alcohol component (A). A rigid polyurethane foam is produced by reacting with 0.5 to 5.5 parts by weight.

The polyoxyalkylene polyol (a
1) is often an alkylene oxide adduct of a polyhydric alcohol, and the monoalcohol (a2) has 1 to 1 carbon atoms.
It is often an aliphatic alcohol of 10 or its alkylene oxide adduct. The proportion of each component in the alcohol component (A) is, for example, 55 to 95% by weight of polyoxyalkylene polyol (a1) and monoalcohol (a).
2) About 5 to 45% by weight. The average hydroxyl value of the alcohol component (A) is 350 to 600 mgKOH /
It is often about g.

The alcohol component (A) further comprises (a
3) Average number of functional groups 2 to 3.5, hydroxyl value 25 to 60 mgK
OH / g and polyoxyethylene unit content of 5 wt% or less, polyoxyalkylene polyol, and (a
4) It may contain at least one component of a polyamine-based polyoxyalkylene polyol obtained by adding an alkylene oxide to an organic polyvalent amine compound.
The polyoxyalkylene polyol (a3) contains a propylene oxide adduct of a polyhydric alcohol, and the polyamine-based polyoxyalkylene polyol (a4) contains an average number of functional groups of 3 to 5 and a hydroxyl value of 150 to 800 m.
Polyols with gKOH / g can be used.

As the aromatic polyisocyanate (B), various polyisocyanates can be used, and one or more polyisocyanates can be used. Polyisocyanate often contains at least polymethylene polyphenyl polyisocyanate, and may be composed of, for example, polymethylene polyphenyl polyisocyanate and tolylene diisocyanate component.

The reaction between the alcohol component (A) and the aromatic polyisocyanate (B) is often carried out in the presence of the water (C) at an isocyanate index of 70 to 150.

The rigid polyurethane foam of the present invention obtained by such a method has a closed cell ratio of about 50 to 90%. The average cell diameter is, for example, 0.1 to 1
It is about 0 mm.

In the present specification, the term "isocyanate index" refers to the amount of aromatic polyisocyanate used in the actual reaction in the reaction with a compound having an active hydrogen atom such as A1, polyol, monoalcohol and water. , A0 is the theoretical amount of polyisocyanate required for the reaction with the active hydrogen atom of the compound, the formula (A1 /
A0) × 100.

The present invention will be described in detail below.

The alcohol component (A) is a polyoxyalkylene polyol (a1) and a monoalcohol (a).
At least 2) is included. The contents of these components are as follows.

Polyoxyalkylene polyol (a1) The polyoxyalkylene polyol (a1) has an average number of functional groups of 2.5 to 6 (preferably 2.8 to 6, more preferably about 3 to 6) and a hydroxyl value of 400 to 600 mgK.
OH / g (preferably 400 to 550 mg KOH / g,
More preferably about 425 to 525 mg KOH / g)
have. Polyoxyalkylene polyol (a1)
If the hydroxyl value is less than 400 mgKOH / g, the cell diameter of the resulting foam will be small, and the effective compression ratio will tend to decrease. If it exceeds 600 mgKOH / g, the closed cell ratio will tend to be too high.

This polyoxyalkylene polyol (a
1) is preferably a non-amine initiated polyoxyalkylene polyol. Such a polyol (A) can be composed of an alkylene oxide adduct of a polyhydric alcohol.

As the polyhydric alcohol, various compounds having two or more hydroxyl groups, such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 1, Diols such as 5-pentanediol and 1,6-hexanediol, glycerin, diglycerin, trimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol, diglycerin, methylglucoside, sorbitol, polysaccharides such as sucrose, etc. Examples thereof include compounds having 3 or more hydroxyl groups. These polyhydric alcohols can be used alone or in admixture of two or more. Preferred polyhydric alcohols include polyhydric alcohols containing no oxyethylene units, particularly compounds having 3 or more hydroxyl groups in one molecule, and particularly compounds having 3 to 6 hydroxyl groups (eg, glycerin, sorbitol, sucrose). Etc.) are included.

The alkylene oxide includes, for example, ethylene oxide and propylene oxide having 2 carbon atoms.
About 4 alkylene oxides are included. These alkylene oxides may be used alone or in combination of two or more. Preferred alkylene oxides include propylene oxide.

Among the polyols (a1) composed of the alkylene oxide adduct of polyhydric alcohol, polyoxypropylene polyol having propylene oxide added is preferable as the polyol (a1) in order to enhance impact absorption. Further, in order to suppress scorch at the time of foam formation, as the polyol (a1), an alkylene oxide adduct of a polyhydric alcohol having 3 or more hydroxyl groups in one molecule such as glycerin and sorbitol, particularly polyoxyl is used. Propylene polyol is preferred.

[0029] The mono alcohol (a2) mono alcohol (a2) is a hydroxyl value 400~1800mg
KOH / g (preferably 500-1500 mg KOH /
g, more preferably 550-1200 mg KOH / g
Various monohydroxy compounds can be used as long as they have the same degree. The hydroxyl value of the monoalcohol (b) is 400 mg
If it is less than KOH / g, the effective compression rate tends to decrease due to plasticization, and the hydroxyl value is 1800 mgKOH / g.
It is difficult to obtain monoalcohol exceeding g.

Examples of the monoalcohol (a2) include methanol, ethanol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, s-butyl alcohol, t-butyl alcohol, pentyl alcohol, hexyl alcohol, octyl alcohol, 2 -Aliphatic alcohols having about 1 to 10 carbon atoms such as ethylhexyl alcohol; glycol monoethers (eg, 2 carbon atoms such as ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, and 1,6-hexanediol)
~ 6 mono-C1-4 alkyl ether of glycol,
Monoaryl ether, monoaralkyl ether, etc.); aliphatic alcohols having 1 to 10 carbon atoms, for example,
Examples thereof include alkylene oxide adducts of 2-ethylhexyl alcohol (eg, ethylene oxide, propylene oxide adducts, etc.). These monoalcohols can be used alone or in combination of two or more.

Preferred monoalcohols (a2) include aliphatic alcohols having 1 to 10 carbon atoms (preferably 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms) or alkylene oxide adducts thereof, and 2 to 6 carbon atoms. (Preferably 2 to 4)
Monoglycol ethers of the order of magnitude are preferred. Examples of the glycol monoether include cellosolves (for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether and other ethylene glycol monoalkyl ethers, ethylene glycol monophenyl ether, etc. Monoaralkyl ethers such as ethylene glycol monoaryl ether and ethylene glycol monobenzyl ether), glycol monoalkyl ethers, monoaryl ethers and monoaralkyl ethers corresponding to these cellosolves (eg, propylene glycol monomethyl ether, propylene glycol monoether). Ethyl ether etc.) and the like. These monoethers are often monoalkyl ethers,
The alkyl group preferably has about 1 to 4 (preferably 1 to 3) carbon atoms. Examples of such monoalkyl ethers include ethylene glycol monomethyl ether and ethylene glycol monoethyl ether.

When the alcohol component (A) is composed of the polyoxyalkylene polyol (a1) and the monoalcohol (a2), the ratio of both can be selected within a wide range depending on the type of each alcohol component. Content of polyoxyalkylene polyol (a1) is 55 to 95% by weight
(More than 55% by weight and 95% by weight or less), and the content of the monoalcohol (a2) is 5 to 45% by weight (5% by weight or more and less than 45% by weight). In the preferred alcohol component (A), the polyoxyalkylene polyol (a
The ratio of 1) to monoalcohol (a2) is, for example, the former /
The latter = 60 to 95/5 to 40% by weight, preferably 65 to
90/10 to 35% by weight, more preferably 70 to 85
/ 15 to 30% by weight. Alcohol component (A)
The content of the monoalcohol (a2) therein is often 10 to 30% by weight, particularly about 10 to 25% by weight.

The alcohol component (A) may further contain other hydroxy compound in addition to the components (a1) and (a2). Thus, in hydroxy compounds,
For example, the second polyoxyalkylene polyol (a3) having a smaller hydroxyl value than the first polyoxyalkylene polyol and the polyamine-based polyoxyalkylene polyol (a4) are included. The alcohol component (A) may include at least one of these polyols (a3) and (a4), or may include both components. The polyoxyalkylene polyol (a3) contributes to cell openings and the like, and the polyamine-based polyoxyalkylene polyol (a4) contributes to uniformization of cell diameters. The contents of these polyol components are as follows.

Polyoxyalkylene polyol (a3) This polyol (a3) has an average number of functional groups of 2 to 3.5 (preferably 2.5 to 3.5, more preferably 2.7 to).
3.3), hydroxyl value 25 to 60 mgKOH / g (preferably 28 to 60 mgKOH / g, more preferably 30)
˜60 mgKOH / g) and the content of polyoxyethylene units is 5% by weight or less (preferably 0).
Is about 5% by weight, more preferably about 0 to 3% by weight). The hydroxyl value of the polyol (c) is 60 mgKOH / g
Or the polyoxyethylene content exceeds 5% by weight, the cell opening is suppressed and the hydroxyl value is 25 mgKO.
If it is less than H / g, it is difficult to introduce oxyethylene units.

The ratio of the primary hydroxyl group at the terminal to the total hydroxyl groups of the polyoxyalkylene polyol (a3) is 15
% Or less. When the proportion of the terminal primary hydroxyl group exceeds 15%, the opening of the cell is suppressed and the closed cell ratio tends to be too high.

Such a polyol (a3) is a polyhydric alcohol having an average number of functional groups of 2 to 3.5 and a hydroxyl value of 25 to
It can be obtained by addition or addition polymerization of alkylene oxide such as propylene oxide while controlling at 60 mgKOH / g.

The polyhydric alcohol having 2 to 3.5 functional groups is, for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol,
1,3-butanediol, 1,4-butanediol,
A diol (difunctional polyhydric alcohol) such as 1,5-pentanediol or 1,6-hexanediol, or a trifunctional polyhydric alcohol such as glycerin, trimethylolpropane or trimethylolethane may be used alone, or is suitable. It can be prepared by mixing in various proportions. Further, a polyhydric alcohol having 4 or more hydroxyl groups in one molecule (for example, pentaerythritol, dipentaerythritol, diglycerin, methylglucoside, sorbitol, sucrose, and other polysaccharides) and the bifunctional polyhydric alcohol. And / or trifunctional polyhydric alcohol can also be prepared by mixing at an appropriate ratio such that the average number of functional groups is 3.5 or less.

As the alkylene oxide added to the polyhydric alcohol, ethylene oxide,
An alkylene oxide having about 2 to 4 carbon atoms such as propylene oxide is included. The preferred polyoxyalkylene polyol (a3) can be composed of a propylene oxide adduct of the polyhydric alcohol.

The polyoxyalkylene polyol (a3) obtained by adding an alkylene oxide to a polyhydric alcohol can be used alone or in combination of two or more to control the average number of functional groups.

The ratio of the polyol (a3) to the entire alcohol component (A) is, for example, 0 to 20% by weight, preferably 1 to 15% by weight, more preferably 3 to 10% by weight. When the amount of the polyol (a3) exceeds 20% by weight, a rigid polyurethane foam having open cells,
It is difficult to achieve both low density and high strength.

Polyamine Polyoxyalkylene Polyol (a4) This polyamine polyol (a4) has an average number of functional groups of 3
To 5 (preferably 3.2 to 4.7, more preferably about 3.3 to 4.5) and hydroxyl value 150 to 800 mg
KOH / g (preferably 200 to 700 mg KOH /
g, more preferably about 300 to 600 mg KOH / g).

In the polyamine-based polyol (a4),
The proportion of primary hydroxyl groups is 15% or less of the total hydroxyl value.

The polyamine-based polyol (a4) can be obtained by using an organic polyvalent amine compound containing a nitrogen atom as an initiator to add or add-polymerize an alkylene oxide to adjust the hydroxyl value within the above range.

The polyvalent amine compound includes a compound having at least two active hydrogen atoms derived from an amino group and at least one active hydrogen atom derived from a hydroxyl group in the molecule, and at least three compounds derived from an amino group. Compounds having active hydrogen atoms are included. Specifically, the organic polyvalent amine compound includes, for example, at least one polyamine compound selected from (poly) alkylene polyamines, alkanol amines and aromatic polyamines.

Examples of such compounds include (poly) alkylene polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, hexamethylenediamine, propylenediamine and dipropylenediamine; monoethanolamine, diethanolamine and triethanolamine. Ethanolamine,
Alkanolamines such as isopropanolamine and isobutanolamine; alicyclic polyamines such as menthenediamine, isophoronediamine, bis (4-amino-3-methylcyclohexyl) methane, diaminodicyclohexylmethane and bis (aminomethyl) cyclohexane; phenylenediamine , Metaxylylenediamine, tolylenediamines (2,4- / 2,6-tolylenediamine, 2,3- / 3,4-tolylenediamine, etc.), diaminodiphenylmethane, diaminodimethyldiphenylmethane, diaminodiethyldiphenylmethane, etc. Aromatic polyamines such as diaminodiphenylmethanes and polymethylenepolyphenylpolyamines; and alicyclic amines such as aminoethylpiperazine and diaminopyridine. These organic polyvalent amine compounds can be used alone or in combination of two or more. Among these organic polyvalent amine compounds, (poly) alkylene polyamines such as ethylenediamine and aromatic polyamines such as tolylenediamines are preferable.

The polyol (a4) is useful for making the cell diameter of the foam finer. The content of the polyol (a4) with respect to the alcohol component (A) is, for example, 0 to 20% by weight, preferably 1 to 18% by weight (for example, 3 to 17% by weight), and more preferably about 5 to 17% by weight. is there. When the content of the polyol (a4) exceeds 20% by weight, the cell diameter becomes fine and the effective compression rate tends to decrease.

The alcohol component (A) is the polyol (a
When 3) and / or the polyamine-based polyol (a4) is included, the ratio of each component can be appropriately selected from the range that does not impair the strength and effective compressibility of the foam, for example, the following range.

Polyol (a1): 60 to 95% by weight, preferably 62 to 93% by weight, more preferably 65 to 9%
About 0% by weight Monoalcohol (a2): 5 to 30% by weight, preferably 7
-25% by weight, more preferably 10-20% by weight At least one component of the polyol (a3) and the amine-based polyol (a4): 0-40% by weight, preferably 5-35% by weight, and further preferably Is about 10 to 30% by weight.

The preferred alcohol component (A) is 60 to 95% by weight of the polyoxyalkylene polyol (a1) (preferably 62 to 93% by weight, more preferably 65 to 9% by weight).
0% by weight), monoalcohol (a2) 5-30% by weight
(Preferably 7 to 25% by weight, and more preferably 10 to
20 wt%), polyoxyalkylene polyol (a
3) 0 to 20% by weight (preferably 1 to 15% by weight, more preferably about 3 to 10% by weight).

In particular, in order to obtain a rigid polyurethane foam suitable as a shock absorber, the alcohol component (A) preferably contains a polyamine polyol (a4). Such alcohol component (A) includes the following composition.

Polyol (a1): 60 to 95% by weight, preferably 62 to 93% by weight, more preferably 65 to 9%
About 3% by weight Monoalcohol (a2): 5 to 30% by weight, preferably 7
-25% by weight, more preferably about 10-20% by weight Polyol (a3): 0-20% by weight, preferably 1-1
5% by weight, more preferably about 3 to 10% by weight Amine polyol (a4): 0 to 20% by weight, preferably 3 to 20% by weight, more preferably about 5 to 17% by weight.

The average hydroxyl value of the alcohol component (A) composed of a plurality of components can be adjusted by the types and ratios of the plurality of components within a range that does not impair properties such as strength and effective compressibility of the foam. The average hydroxyl value of the alcohol component (A) is, for example, 350 to 750 mgKOH /
g, preferably 400 to 700 mgKOH / g, and more preferably about 450 to 680. When the average hydroxyl value of the alcohol component (A) exceeds 750 mgKOH / g, the closed cell ratio becomes too high, and 350 mgKOH / g
If it is less than the range, the strength required for the impact absorbing material cannot be satisfied even if the foam density is increased.

The alcohol component (A) may optionally contain other polyol components such as the polyhydric alcohol to which alkylene oxide is not added and polyester polyol.

The aromatic polyisocyanate (B) for forming polyurethane by the reaction with the alcohol component (A) is not particularly limited as long as it is aromatic and can form a rigid polyurethane foam. Examples of polyisocyanates include tolylene diisocyanate, phenylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl polyisocyanate, and naphthalene diisocyanate. These aromatic polyisocyanates can be used alone or in combination of two or more.

Among these polyisocyanates, polymethylene polyphenyl polyisocyanate, diphenyl methane diisocyanate and their derivatives, and tolylene diisocyanate (TD) from the viewpoints of reactivity and economy.
I), crude tolylene diisocyanate and their derivatives are frequently used. The polymethylene polyphenyl polyisocyanate can be obtained, for example, by phosgenating a condensed amine produced by a condensation reaction between aniline and formaldehyde, and may be a mixture having different degrees of polymerization. Examples of the derivative include prepolymers obtained by the reaction of the above polyisocyanate and polyols, modified polyisocyanates (for example, dimers, trimers and other multimers, carbodiimides, burette modified polyisocyanates, alohanate modified products). , Modified products such as urea modified products) and the like.

Among the above-mentioned aromatic polyisocyanates, particularly, crude MDI, C-MDI and polymeric MDI.
Polymethylene polyphenyl polyisocyanate, also referred to as, is preferred. Furthermore, the polymethylene polyphenyl polyisocyanate preferably has a viscosity at 25 ° C. of 200 millipascal-seconds (centipoise) or less. Such polymethylene polyphenyl polyisocyanate is commercially available, for example, from the trade name “Lupranate M-20S”.
(Viscosity 180 millipascal-seconds (centipoise) at 25 ° C.), “Luplanate M-12S” (viscosity 120 millipascal-seconds (centipoise) at 25 ° C.) available from Takeda Birdish Urethane Industry Co., Ltd. "Millionate MR-200" from Nippon Polyurethane Industry Co., Ltd. under the trade name "Sumijour 44V-
20 "and" Sumijour 44V-10 "are available from Sumitomo Biurethane Co., Ltd., and the product name" Baby 135 "is available from Mitsubishi Kasei Dow.

The aromatic polyisocyanate (B) preferably contains at least the above-mentioned polymethylene polyphenyl polyisocyanate, and may be constituted by polymethylene polyphenyl polyisocyanate alone. Aromatic polyisocyanates (particularly polyisocyanates that exhibit rigidity)
It is preferable to use together. In particular, in order to obtain a foam as an impact absorbing material, a tolylene diisocyanate component (for example, tolylene diisocyanate or a derivative thereof, crude tolylene diisocyanate or a derivative thereof) is used in combination with the polymethylene polyphenyl polyisocyanate. Is preferred. The derivatives include prepolymers, modified polyisocyanates (for example, burette reaction products, carbodiimide-modified products, etc.), dimers, trimers, and the like, as described above. By using the polyisocyanate and its derivative in combination, the rigidity of the obtained foam is increased and the effective compression rate can be further increased. The tolylene diisocyanate is available from Takeda Pharmaceutical Co., Ltd. under the trade name "Takenate-80", and the crude tolylene diisocyanate is available under the trade name "Takenate-4040".
C "is available from Takeda Pharmaceutical Company Limited.

The aromatic polyisocyanate (B)
May contain other polyisocyanate such as aliphatic polyisocyanate such as hexamethylene diisocyanate and alicyclic polyisocyanate such as isophorone diisocyanate, if necessary.

In the method of the present invention, a rigid polyurethane foam is produced by reacting the alcohol component (A) with the aromatic polyisocyanate (B) in the presence of water as a blowing agent. At that time, with respect to 100 parts by weight of the alcohol component (A), 2.5 to 5.5 parts by weight of water (C) as a foaming agent, preferably 3 to 5 parts by weight, more preferably 3.5 to 4 parts. It is important to react with about 0.5 parts by weight. When the amount of water used is small, it is difficult to obtain a rigid polyurethane foam, and it is difficult to reduce the density of the foam, and when the amount of water used is too large, it tends to be a low-density foam, Dimensional stability tends to decrease.

In the above reaction, it is preferable to use only water as a foaming agent, but if necessary, a low boiling point liquid such as halogenated hydrocarbon or pentane may be used as a foaming agent together with water. .

The reaction between the alcohol component (A) and the aromatic polyisocyanate (B) in a reaction system in the presence of water is carried out by a suitable isocyanate index, for example, an isocyanate index of 70 to 150, preferably 80 to 140, and further It is preferable to carry out at about 90 to 130.

Various additives such as, for example,
You may add additives, such as a foam stabilizer, a catalyst, flame retardancy, an antioxidant, a viscosity reducing agent, and a coloring agent. As the foam stabilizer, an organic polysiloxane copolymer generally used for an ointment slab, a hot mold or a rigid foam is preferably used. Such foam stabilizers include, for example, Gold. Schmidt "B-8404", "B-8017",
"L-5410", "L-54" manufactured by Nippon Unicar Co., Ltd.
20 "," SZ-1127 "," L-582 "," SH-190 "," SH-1 "manufactured by Toray Dow Corning Co., Ltd.
92 "," SH-193 "," F- "manufactured by Shin-Etsu Chemical Co., Ltd.
345 ”,“ F-341 ”,“ F-242T ”and the like. The amount of the foam stabilizer used is, for example, about 0.01 to 3 parts by weight, preferably about 0.05 to 1 part by weight, relative to 100 parts by weight of the alcohol component (A).

Interestingly, according to the invention, the relatively active foam stabilizers for slab foams (for example B-80).
When 17) is used, a foam having extremely fine cells can be formed, and as the activity of SH-193 and F-345 is decreased, a foam having coarse cells can be formed. Therefore, according to the present invention, the cell size can be adjusted by selecting the activity of the foam stabilizer to be used or by mixing the foam stabilizers having different activities. A foam having a large cell diameter is useful as a shock absorber, for example.
The activity of the foam stabilizer can be adjusted by factors such as the silicon content, the ethylene oxide content, and the surface tension of the organic polysiloxane.

As the catalyst, a conventional catalyst component such as an amine-based catalyst, a tin-based catalyst or a lead-based catalyst can be used. Of these catalysts, amine-based catalysts, especially tertiary amine-based catalysts are often used. Examples of the tertiary amine-based catalyst include, for example, tetramethylethylenediamine, tetramethylhexanediamine (TMHDA, "Kaolizer No. 1" (manufactured by Kao Corporation), and "Toyocat M".
R ”(manufactured by Tosoh Corporation), pentamethyldiethylenetriamine (PMDETA,“ Kaolizer No. 3 ”)
(Manufactured by Kao Corporation), "Dabco 33LV" (manufactured by Air Products)), bis (2-dimethylaminoethyl)
Ether ("Toyocat ET" (manufactured by Tosoh Corporation))
And so on. These can be used alone or as a mixture.

In particular, a mixed catalyst of TMHDA and bis (2-dimethylaminoethyl) ether is preferably used in the present invention. The ratio of TMHDA and bis (2-dimethylaminoethyl) ether can be selected within a wide range, and for example, former / latter = 10/90 to 95/5 (parts by weight), preferably 30/70 to 90/10 ( Parts by weight),
More preferably, it is about 50/50 to 90/10 (parts by weight).

As the flame retardant, a conventional component such as phosphates such as trischloropropyl phosphate (TCPP) can be used.
When premixing the alcohol component (A), for example, propylene carbonate or the like can be used.

According to the method of the present invention, substantially only water is used as a foaming agent to react an alcohol component (A) having a predetermined composition with an aromatic polyisocyanate (B) to absorb impact. A rigid polyurethane foam suitable as a material or a structural material can be obtained. By adding the polyamine-based polyol (a4) as a part of the alcohol component (A), the cell diameter of the foam can be made uniform and the properties as a shock absorber can be improved.

The rigid polyurethane foam obtained by the above reaction has closed cells and has high compressive strength and effective compressibility. Moreover, even if the thickness is small, the shock absorbing property and the cushioning property are high. The closed cell ratio of the rigid polyurethane foam is 50 to 90%, preferably 55 to 90%.
%, And more preferably about 60 to 90%. When the closed cell ratio is less than 50%, the strength of the foam decreases, and
If it exceeds%, the dimensional stability tends to decrease. The open cell rate (%) can be expressed as 100-closed cell rate (%).

Further, the average cell diameter of the cells of the rigid polyurethane foam is, for example, 0.1 to 10 mm, preferably 0.2 to 5 mm, more preferably 0.5 to 3 m.
m. If the average cell diameter is less than 0.5 mm,
If the effective compression rate of the foam decreases and exceeds 10 mm,
In some cases, the cell diameter cannot be made uniform, and the foam is likely to collapse when the foam is produced, so that the foam cannot be stably manufactured.

The density of the rigid polyurethane foam can be selected in a wide range, and the density of the foam by free foaming is, for example, 30 to 60 kg / m ³ , preferably 30 to 57 k.
g / m ³ , more preferably about 32 to 55 kg / m ³ . If the density of the foam is less than 30 kg / m ³ , the strength tends to decrease, and if it exceeds 60 kg / m ³ , weight reduction is difficult. The expansion ratio of the rigid polyurethane foam is, for example, 1.5 to 30 times, preferably 2 to
It is about 20 times, more preferably about 3 to 10 times.

Further, the rigid polyurethane foam has high strength even if it has a low density, for example, a compressive strength of 2 kg.
/ Cm ² or more (preferably ^{2 to 6} kg / cm ² , more preferably about 2.3 to 5 kg / cm ² ) in many cases. Further, the rigid polyurethane foam has a high effective compression rate, for example, 65% or more (preferably 70 to 90%,
More preferably, it has an effective compression rate of about 75 to 90%. Therefore, it can be effectively used as a shock absorber among structural materials.

The rigid polyurethane foam of the present invention is useful as a shock absorbing material, a cushioning material, etc., as described above, but since it has closed cells in addition to structural materials such as structures having a sandwich structure and building structures. It is also useful as a heat insulating material. Furthermore, since it also has open cells, it can be used as a sound absorbing material.

[0073]

EFFECTS OF THE INVENTION According to the present invention, a simple method of using a specific alcohol component composed of a plurality of hydroxy compounds described above and substantially using only water without using a halogenated hydrocarbon as a blowing agent. Thus, a rigid polyurethane foam having high strength and high effective compression rate can be manufactured.
Further, by adjusting the composition of the alcohol component (A), it is possible to stably produce a rigid polyurethane foam having closed cells and having a high impact absorption or a high buffering property even if the thickness is small. Further, the rigid polyurethane foam has high mechanical strength and is lightweight even at low density. Therefore, the rigid polyurethane foam is suitable as a shock absorber, a structural material and the like.

[0074]

The present invention will be described in more detail based on the following comparative examples and examples, but the present invention is not limited to these examples.

Materials used in Comparative Examples and Examples and their abbreviations are as follows. When displaying the hydroxyl value, the unit (mgKOH / g) is omitted.

(A) Alcohol component polyol (a1) Polyol: Polyoxyalkylene polyol obtained by adding propylene oxide to sorbitol (hydroxyl value 500) Polyol: Mixture of sucrose and glycerin (average functional group number: 5.3) with propylene oxide Polyoxyalkylene polyol with a hydroxyl value (460) Polyol: Polyoxyalkylene polyol with a propylene oxide added to sorbitol (hydroxyl value 300) Monoalcohol (a2) Monoalcohol: Ethylene glycol monoethyl ether (EE, hydroxyl value) 623) monoalcohol: isopropyl alcohol (hydroxyl value 935) polyol (a3) a polyol: glycerol polyoxyalkylene polyol obtained by adding propylene oxide (hydroxyl 5
6) Amine-based polyol (a4) polyol: 2,4 / 2,6-tolylenediamine (8
0/20 mixture, TDA) and triethanolamine mixture (average number of functional groups 3.6) with propylene oxide added polyoxyalkylene polyol (hydroxyl value 450) Polyol: ethylenediamine with propylene oxide added polyoxy Alkylene Polyol (Hydroxyl Value 510) (B) Aromatic Polyisocyanate 44V-10: Polymerylene Polyphenyl Polyisocyanate (Sumitomo Bayer Urethane Co., Ltd., trade name “Sumijour 44V-10”, viscosity 120 at 25 ° C. Millipascal second (centipoise) 4040C: Cooled tolylene diisocyanate (Takenate 4040C, trade name, manufactured by Takeda Pharmaceutical Co., Ltd.)
SH-193: Silicone type foam stabilizer (trade name "SH-193" manufactured by Toray Dow Corning Co., Ltd.) Additive B-8404: Silicone type foam stabilizer (made by Gold Schmidt, trade name "B-8404"") TCPP: tris chloropropyl phosphate TE-30: tetramethyl hexane diamine (TMHD
A) / bis (2-dimethylaminoethyl) ether = 7
Mixed catalyst of 0/30 (weight ratio).

CT: Time until the reaction mixture starts to rise into a cream after starting the mixing of the reaction solution (seconds) GT: Time until the thickening occurs and gel strength develops after the starting of the mixing of the reaction solution (seconds) Further, the properties of the obtained foam were measured as follows.

Compressive strength: The strength of the foam during compression in the rising direction was measured. 1 unless otherwise specified
The strength at 0% compression is shown. The compressive strength for use as an impact absorber is shown by the level value of AB of the compression curve in FIG. 1, but numerically there is no great difference from the above 10% compressive strength.

Examples 1 to 8 and Comparative Examples 1 to 7 Alcohol component (A) in an amount 3 times the amount shown in Table 1 (g),
A foam stabilizer, water and a catalyst were mixed to prepare a premix (premix) in a polyethylene beaker (volume: 2 liter). This premix was transparent and uniform.

The temperature of the premix was adjusted to 25 ° C.,
Three times the amount of the aromatic polyisocyanate (B) shown in Table 1 prepared in advance at 25 ° C. was weighed in the beaker, and immediately thereafter, using a homodisper, the rotation speed was 300 to 500 rp.
The mixture was adjusted by stirring for 5 seconds at m, and the obtained mixture was poured into a wooden box (25 cm square) in which release paper was folded to obtain a free-foamed foam. Table 1 shows the reactivity of the foam and the density, closed cell ratio, compressive strength, effective compressibility, dimensional stability and average cell diameter of the obtained foam.
~ Shown in Table 3.

[0081]

[Table 1]

[0082]

[Table 2]

[0083]

[Table 3] As is clear from Tables 1 to 3, the foams obtained in Examples 1 to 8 all had a compressive strength of 2 kg / cm ² or more,
It has a closed cell rate of 70 to 90% and an effective compression rate of 70 to 90%, and has excellent properties as a rigid polyurethane foam. Further, it is possible to stably foam, and there is no shrinkage, and dimensional stability is high. Although the foams obtained in Comparative Examples 1 and 3 have closed cells,
Shrinkage occurs, dimensional stability is significantly reduced, the foam obtained in Comparative Example 2 has open cells, and its compressive strength is low. In Comparative Example 4, the elasticity is reduced and the dimensional stability is significantly reduced, and in Comparative Example 5, a high effective compression ratio cannot be obtained. Further, in Comparative Example 6 in which the amount of water is small, it is possible to obtain a rigid polyurethane foam having a low closed cell ratio, but in Comparative Example 7 in which the effective compressibility required for a shock absorber is practically low and the amount of water is large. Although it is possible to obtain a rigid polyurethane foam having a low closed cell rate, the dimensional stability is lowered due to the low density and compressive strength,
It is difficult to satisfy the practical properties as a shock absorber and a structural material.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between compressive stress and compressibility.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Tsuchiya 5-3-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation

Claims (19)

[Claims] 1. A polyoxyalkylene polyol having (a1) an average number of functional groups of 2.5 to 6 and a hydroxyl value of 400 to 600 mgKOH / g, and (a2) a hydroxyl value of 400 to 18
An alcohol component (A) containing 00 mgKOH / g of a monoalcohol and having a polyol (a1) content of more than 55% by weight and 95% by weight or less, and (B) an aromatic polyisocyanate, A) 100 to 100 parts by weight of water (C) as a foaming agent 2.5 to 5.5
A method for producing a rigid polyurethane foam, which comprises reacting parts by weight. 2. A polyoxyalkylene polyol (a1)
The method for producing a rigid polyurethane foam according to claim 1, wherein is an alkylene oxide adduct of a polyhydric alcohol. 3. A polyoxyalkylene polyol (a1)
Has an average number of functional groups of 2.5 to 6 and a hydroxyl value of 400 to 55
The method for producing a rigid polyurethane foam according to claim 1, which is 0 mgKOH / g of polyoxypropylene polyol. 4. The monoalcohol (a2) has 1 to 1 carbon atoms.
The method for producing a rigid polyurethane foam according to claim 1, which is an aliphatic alcohol of 0 or an alkylene oxide adduct thereof. 5. The production of a rigid polyurethane foam according to claim 1, wherein the alcohol component (A) is composed of 60 to 95% by weight of the polyoxyalkylene polyol (a1) and 5 to 40% by weight of the monoalcohol (a2). Method. 6. The method for producing a rigid polyurethane foam according to claim 1, wherein the average hydroxyl value of the alcohol component (A) is 350 to 750 mgKOH / g. 7. The method for producing a rigid polyurethane foam according to claim 1, wherein the aromatic polyisocyanate (B) contains at least polymethylene polyphenyl polyisocyanate. 8. The method for producing a rigid polyurethane foam according to claim 7, wherein the aromatic polyisocyanate (B) contains polymethylene polyphenyl polyisocyanate and a tolylene diisocyanate component. 9. The method for producing a rigid polyurethane foam according to claim 1, wherein the reaction is carried out with an isocyanate index of 70 to 150. 10. The alcohol component (A) further comprises (a)
3) Average number of functional groups 2 to 3.5, hydroxyl value 25 to 60 mgK
OH / g and polyoxyethylene unit content of 5 wt% or less, polyoxyalkylene polyol, and (a
4) The method for producing a rigid polyurethane foam according to claim 1, comprising at least one component of a polyamine-based polyoxyalkylene polyol obtained by adding an alkylene oxide to an organic polyvalent amine compound. 11. A polyoxyalkylene polyol (a
The method for producing a rigid polyurethane foam according to claim 10, wherein 3) is a propylene oxide adduct of a polyhydric alcohol. 12. A polyoxyalkylene polyol (a
The method for producing a rigid polyurethane foam according to claim 10, wherein the proportion of primary hydroxyl groups at the ends is 15% or less of the total hydroxyl groups in 3). 13. The polyamine-based polyoxyalkylene polyol (a4) has an average number of functional groups of 3 to 5 and a hydroxyl value of 1.
The method for producing a rigid polyurethane foam according to claim 10, having a content of 50 to 800 mg KOH / g. 14. The polyamine-based polyoxyalkylene polyol (a4) is an adduct of an alkylene oxide with at least one organic polyvalent amine compound selected from (poly) alkylene polyamines, alkanol amines and aromatic polyvalent amines. The method for producing a rigid polyurethane foam according to claim 10. 15. The alcohol component (A) comprises polyoxyalkylene polyol (a1) 60 to 95% by weight, monoalcohol (a2) 5 to 30% by weight, polyoxyalkylene polyol (a3) and polyamine-based polyamine. The method for producing a rigid polyurethane foam according to claim 14, which comprises 0 to 40% by weight of at least one component of the oxyalkylene polyol (a4). 16. The method for producing a rigid polyurethane foam according to claim 10, wherein the average hydroxyl value of the alcohol component (A) is 350 to 750 mgKOH / g. 17. A polyoxyalkylene polyol having (a) an average number of functional groups of 2.5 to 6 and a hydroxyl value of 400 to 600 mg KOH / g, and (b) a hydroxyl value of 400 to 180.
(C) foaming (A) an alcohol component containing 0 mgKOH / g of monoalcohol, and the content of the polyol (a) is more than 55% by weight and 95% by weight or less, and (B) an aromatic polyisocyanate. A rigid polyurethane foam having a closed cell rate of 50 to 90% obtained by reacting in the presence of water as an agent. 18. (c) The average number of functional groups 2-3.
5, at least a polyoxyalkylene polyol having a hydroxyl value of 25 to 60 mg KOH / g and a polyoxyethylene unit content of 5% by weight or less, and (d) a polyamine-based polyoxyalkylene polyol obtained by adding an alkylene oxide to an organic polyvalent amine compound. The rigid polyurethane foam according to claim 17, which is obtained by reacting (A) an alcohol component containing one component with (B) an aromatic polyisocyanate in the presence of (C) water as a foaming agent. 19. The rigid polyurethane foam according to claim 17, which has an average cell diameter of 0.1 to 10 mm.