JPH08176257A - Polyol composition and production of rigid polyurethane foam - Google Patents

Abstract

PURPOSE: To improve the reactivity in producing a low-density rigid polyurethane foam and also improve the vol. change (low-temp. dimensional stability) of the resulting, foam. CONSTITUTION: A polyol compsn. comprising 99.9-80wt.% polyol having a hydroxyl value of 200-600mgKOH/g and 0.1-20wt.% alkanolamine having a mol. wt. of 300 or lower is reacted with a polyisocyanate in the presence of at least one blowing agent selected from among water and halohydrocarbons, a catalyst, a silicone surfactant, and other auxiliary additives, giving a 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 polyol composition used for producing a rigid polyurethane foam which is often used as a heat insulating material for electric refrigerators, buildings, baths, freezers and the like, and a method for producing the rigid polyurethane foam.

[0002]

2. Description of the Related Art Rigid polyurethane foam has been known as a good heat insulating material and is widely used as a heat insulating material for electric refrigerators, buildings, bathtubs, frozen warehouses, pipes, etc. because of its excellent moldability and workability. There is.

To produce a rigid polyurethane foam, a component A comprising a polyol, a foaming agent, a catalyst, a silicone surfactant and an auxiliary agent and a component B comprising a polyisocyanate are mixed and reacted by a foaming machine or a spray machine. , Foam-harden in a mold with the desired shape,
In most cases, a method of spraying and foaming and hardening the target area is used on site. At this time, the volume ratio of the component A to the component B is about 1 due to the performance limitation of the foaming machine or the spray machine.
It is set near 1 against.

The blowing agent for this rigid polyurethane foam is conventionally trichloromonofluoromethane (CFC-11).
And water has been used. However, trichloromonofluoromethane poses a risk of depleting the ozone layer in the stratosphere, and from the standpoint of protecting the global environment, it has been decided that certain Freon gas containing trichloromonofluoromethane will be regulated in production and use after 1995. Has been done.

Therefore, various blowing agents have been investigated in place of trichloromonofluoromethane. Examples of the alternative blowing agent include hydrochlorofluorocarbons such as 1,1-dichloro-1-fluoroethane (hereinafter abbreviated as HCFC-141b) and hydrochlorofluorocarbons (eg HFC-134a, HFC-356).
Etc.), cyclopentane, pentane, and other aliphatic hydrocarbons.

[0006] These foaming agents function as foaming agents by evaporating the foaming agent dissolved in the polyol due to the reaction heat of the reaction between the polyol and polyisocyanate to form a urethane bond, and a foam is formed.

In addition to such a physical blowing agent, water is often used together as a chemical blowing agent. HCFC-14
When a non-regulated CFC such as 1b is used as a foaming agent as a foaming agent, the reactivity in the initial stage decreases, resulting in a decrease in productivity and a problem of molding properties such as dripping when sprayed. In addition, there is a drawback that the low-temperature dimensional stability and strength of the rigid polyurethane foam deteriorate when compared at the same density.

In order to solve the drawbacks and problems of such an alternative blowing agent for trichloromonofluoromethane, many polyol compositions suitable for producing rigid polyurethane foams have been studied.

For example, the technique disclosed in Japanese Patent Laid-Open No. 3-258824 is one example. The technology shown here is an alternative blowing agent for trichloromonofluoromethane (preferably HCFC-123 or HCFC-141b) which is a specific prepolymer obtained by urethane-modifying a polyisocyanate with a low molecular weight polyol and a polyol having a specific composition.
The present invention relates to a method for producing a rigid polyurethane foam by using. As the polyol, (C) a polyol having toluenediamine and an aliphatic amine as an initiator or / and a polyol having (C ′) methylglucoside as an initiator, (D) a polyol having trimethylolpropane as an initiator, and (E) A low molecular weight diol or triol is added in a weight ratio of [(C) or / and (C ′)] :( D) = 1: 0.25 to 4, [(C) or / and (C ′) + (D )] :( E) = 1: 0.05
It is characterized by using the thing of -0.3. Here, the low molecular weight diol or triol (E) is an aliphatic polyol, and specific examples thereof include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerin, and trimethylolpropane. Although exemplified, there is no description about alkanolamine. The density of the rigid polyurethane foam in the examples is 30.8-3.
It is 3.3 kg / m ³ , which does not sufficiently meet the demand for improving the low temperature dimensional stability of the rigid polyurethane foam at a lower density. Moreover, no specific reference is made to the point of reactivity.

Within the range confirmed by experiments by the present applicant, particularly when alkylene oxide is added using alkanolamines as a part of the initiator of polyol, alkylene oxide is added to alkanolamines, and the molecular weight thereof is It exceeds 300. The polyol thus obtained has a low amino group concentration in the polyol and is poor in reactivity as compared with a polyol in which a low molecular weight alkanolamine having a molecular weight of 300 or less is mixed.

[0011]

The object of the present invention is to produce a rigid polyurethane foam with an alternative blowing agent of trichloromonofluoromethane, which is good at a low density (29 kg / m ³ or less), which was difficult with the conventional techniques. Provide a polyol composition having excellent low temperature stability (volumetric stability-3% or less) and high reactivity as compared with the case of using a conventional polyol composition, and a method for producing a rigid polyurethane foam To do.

[0012]

As a result of various investigations, the present inventors have found that the intended polyol composition can be obtained by using low molecular weight alkanolamines, and arrived at the present invention.

That is, the gist of the present invention is to use a polyol having a molecular weight of 300 or less, which is used when a rigid polyurethane foam is produced by reacting a polyol with a polyisocyanate in the presence of a blowing agent, a catalyst, a silicone surfactant and an auxiliary agent. Molecular weight alkanolamine 0.1 to 20% by weight and hydroxyl value 200
A polyol composition comprising 99.9 to 80% by weight of a polyol having a content of ˜600 mg KOH / g, wherein the polyol composition is used to produce a rigid polyurethane foam in which the blowing agent is at least one selected from water and halogenated hydrocarbons. It is a manufacturing method.

The low molecular weight alkanolamine used in the present invention is triethanolamine, diethanolamine, monoethanolamine, etc., preferably having a molecular weight of 300 or less, more preferably 250 or less, most preferably 200 or less. Is. Triethanolamine and diethanolamine are particularly suitable because of their high reaction activity. The molecular weight of alkanolamine is 3
If it exceeds 00, the effect of increasing the reactivity and the effect of improving the dimensional stability at low temperature of the obtained rigid polyurethane foam are deteriorated. These alkanolamines may be used alone or in combination of two or more. The amount of the low molecular weight alkanolamine used in the polyol composition is preferably 0.1 to 20% by weight, more preferably 0.5 to 15% by weight,
It is more preferably 1.0 to 16% by weight, and most preferably 1.5 to 10% by weight. When the amount used is less than 0.1% by weight, the reactivity-increasing effect and the low-temperature dimensional stability improving effect of the obtained rigid polyurethane foam decrease, and when the amount used is 20% by weight or more, the polyol composition, the blowing agent, the catalyst,
The volume ratio of the component A consisting of the silicone surfactant and the auxiliary agent and the component B consisting of the polyisocyanate deviates greatly from 1: 1 and becomes a problem.

The polyol having a hydroxyl value of 200 to 600 mgKOH / g means glycerin, trimethylolpropane, pentaerythritol, diglycerin, granulose, sorbitol, α-methylglucoside, triethanolamine, diethanolamine, monoethanolamine, ethylenediamine, diethylenetriamine. , Aniline, toluenediamine, diphenylmethanediamine, novolac, etc. are used as an initiator, and an alkali metal hydroxide such as potassium hydroxide or sodium hydroxide or Pharmine DM-60 [dimethylpalmitylamine (Kao (Manufactured by Co., Ltd.)] in the presence of a known basic catalyst such as propylene oxide or ethylene oxide at 60 ° C. to 140 ° C. The point.

Particularly preferred as the initiator is a polyol using at least one initiator selected from ethylenediamine, triethanolamine, toluenediamine, diphenylmethanediamine, novolac and α-methylglucoside, which are separately synthesized. The use of a polyol obtained by mixing polyols having different initiators does not contradict the gist of the present invention. As the toluenediamine, an ortho body and / or a meta body is used. Further, novolac is a resin containing a plurality of aromatic rings in one molecule, which is generally obtained by condensing phenol and formalin, and refers to a resin having an average number of functional groups of 2 to 5.

The hydroxyl value of the polyol of the present invention is 200 m.
gKOH / g to 600 mgKOH / g is preferable, and more preferably 250 mgKOH / g to 580 mgKO.
H / g, more preferably 300 mg KOH / g to 550
mgKOH / g, most preferably 350 mgKO
H / g to 520 mg KOH / g.

The blowing agent refers to one or more selected from water and halogenated hydrocarbons, and the halogenated hydrocarbon means
For example, HC, which is a hydrochlorofluorocarbon
FC-141b, H which is a hydrofluorocarbon
FC-134a, HFC-356, aliphatic hydrocarbons such as pentane and cyclopentane, and the most preferred blowing agent is HCFC-141b. The blowing agent is used in an amount of 1 part to 50 parts based on 100 parts by weight of the polyol composition. Further, 0.3 to 8 parts by weight of water is used with respect to 100 parts by weight of the polyol composition.

Polyisocyanate is aromatic, aliphatic,
Alicyclic polyisocyanates and modified products thereof, for example, hexamethylene diisocyanate, isophorone diisocyanate, toluylene diisocyanate,
Mention may be made of diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, polymethylene polyphenyl polyisocyanate and urethane or carbodiimide or nurate modifications thereof.
Among these polyisocyanates, generally, a mixture of diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate [an isocyanate known in the art as crude MDI or polymeric MDI, Cosmonate M-50, M- 100, M-200
(Manufactured by Mitsui Toatsu Chemicals, Inc.) and the like can be exemplified. ] Is preferable.

As the foaming catalyst suitable for the present invention, known amine-type and metal-type foaming catalysts can be used. For example, Kaurizer No. 1 and No. Examples thereof include catalysts marketed under the trade name of 3 (product of Kao Corporation). In the present invention, the evaluation of the polyol composition is carried out by a small test called a hand foaming method (polyol composition 100 g), and this evaluation method involves stirring components A and B in a cup using a mixer. Therefore, since it is necessary to secure a stirring time, a foaming test is carried out without a catalyst. However, in the production of a rigid polyurethane foam on a factory line or in the field, the catalyst is used in an amount of 0.01 per 100 parts of the polyol composition. It is essential to use 10 to 10 parts.

The silicone surfactant is SZ-1642.
A conventionally known one such as (manufactured by Nippon Unicar Co., Ltd.) can be used, and it is preferable to use 0.1 part to 5 parts per 100 parts of the polyol composition.

The auxiliaries are flame retardants, pigments, viscosity modifiers and the like, and tris (2-chloropropyl) phosphate (hereinafter abbreviated as TCPP) and the like are listed as an example of the flame retardant and various other additives. It refers to conventionally known auxiliaries such as pigments and viscosity reducing agents such as propylene carbonate and ethylene carbonate.

[0023]

EXAMPLES Examples of the present invention will be shown below to clarify aspects of the present invention. Table 1 shows the polyol initiator used in the examples and comparative examples, the polymerization catalyst of propylene oxide, and the hydroxyl value and viscosity of the polyol. The method of synthesizing these polyols is that an initiator and a polymerization catalyst are charged into an autoclave, the temperature is raised to 110 to 115 ° C., and propylene oxide is sequentially pumped into the autoclave while maintaining the internal pressure of the autoclave at a maximum of 4 kg / m ³ or less. It was done by press fitting. After the completion of the polymerization, neutralization, dehydration and filtration were carried out for purification. Those using Farmin DM60 were used without post-treatment.

[0024]

[Table 1] * 1 Novolak resin with a molecular weight of 300 and 3 functional groups (manufactured by Mitsui Toatsu Chemicals, Inc.) * 2 Triethanolamine * 3 Ethylenediamine * 4 Diphenylmethane diamine (Mitsui Toatsu Chemicals, Inc.) * 5 m -Toluenediamine (manufactured by Mitsui Toatsu Chemicals, Inc.) * 6 α-methyl glucoside * 7 Weight% based on the final product * 8 Dimethylpalmitylamine (manufactured by Kao Corporation)

Polyol compositions were prepared in the weight ratios shown in Tables 2 and 3, and a silicone surfactant, water and a flame retardant tris (2-chloropropyl) phosphate (hereinafter TCP) were used.
Abbreviated as P. ), Water, HCFC-141b in Tables 2 and 3
(The resin mixture is referred to as a resin premix) at the ratio shown in (1) and the temperature is adjusted to 20 ° C. together with M-200 (Polymeric MDI manufactured by Mitsui Toatsu Chemicals, Inc.). The resin premix and M-200 were vigorously stirred at the liquid ratios shown in Tables 2 and 6 for 6 seconds, poured into a box-shaped container having an open upper end, and the time when foaming was started (cream time (C
T), a time gel time (GT) in which the resin turns into a gel and the thread is pulled when the resin is extended, and a tack free time (TFT) in which stickiness disappears even when the resin surface is touched were observed. After curing the obtained rigid polyurethane foam for 24 hours at room temperature, 10 cm × 10 cm × 5
After cutting the sample into the shape of cm and measuring the apparent density,
The volume change rate after standing at -30 ° C for 24 hours was evaluated as the low temperature dimensional stability. The results are shown in Tables 2 and 3.

As shown in Comparative Example A and Examples 1 to 3,
Alkanolamine triethanolamine (TE
The addition of OA) and diethanolamine (abbreviated as DEOA) showed an increase in reactivity and a significant improvement in low temperature dimensional stability as compared to Comparative Example A in which no additive was added. Further, it is clear that DEOA, which has a smaller molecular weight of alkanolamine, has a larger effect in the same weight part. As shown in Comparative Example B and Example 4, the addition of TEOA, which is an alkanolamine, showed an increase in reactivity and a significant improvement in dimensional stability at low temperature, as compared with Comparative Example B without addition.

As shown in Comparative Example C, Example 5, by adding the alkanolamine, DEOA,
An increase in reactivity and a marked improvement in low temperature dimensional stability were seen as compared to the additive-free Comparative Example C. As shown in Comparative Example D, Example 6, by adding the alkanolamine, DEOA, an increase in reactivity and a significant improvement in dimensional stability at low temperature were observed as compared with Comparative Example D without addition. As shown in Comparative Example E, Example 7, the addition of the alkanolamine, DEOA, resulted in an increase in reactivity and a significant improvement in low temperature dimensional stability as compared to Comparative Example E with no addition.

[0028]

[Table 2]

[0029]

[Table 3]

[0030]

As is clear from the results of Examples and Comparative Examples, in the polyol composition of the present invention, since the low molecular weight alkanolamine is present, the autocatalytic action in the reaction with the polyisocyanate is strong. , The reactivity with polyisocyanate is improved. Further, in the polyol composition containing a part of a low molecular weight alkanolamine, particularly diethanolamine, the crosslink density in the polyurethane network structure is improved, the strength of the obtained polyurethane foam is improved and the volume change rate is decreased, that is, at low temperature. The dimensional stability is remarkably improved.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI technical display location C08G 101: 00) C08L 75:04 (72) Inventor Izugawa Takugo, Minami-ku, Aichi 2-1, 1 Mitsui Toatsu Chemical Co., Ltd.

Claims (4)

[Claims] 1. A low-molecular-weight alkanolamine having a molecular weight of 300 or less, which is used when a rigid polyurethane foam is produced by reacting a polyol with a polyisocyanate in the presence of a blowing agent, a catalyst, a silicone surfactant and an auxiliary agent. 1 to 20% by weight and hydroxyl value 200 to 600 mg KO
A polyol composition comprising 99.9 to 80% by weight of H / g of polyol. 2. The polyol composition according to claim 1, wherein the low molecular weight alkanolamine having a molecular weight of 300 or less is at least one selected from diethanolamine and triethanolamine. 3. A method for producing a rigid polyurethane foam, wherein the blowing agent is one or more selected from water and halogenated hydrocarbons, and the polyol composition according to claim 1 is used. 4. The blowing agent is water and 1,1-dichloro-1.
-The method for producing a rigid polyurethane foam according to claim 3, which is fluoroethane.