JP3808991B2 - Method for producing rigid polyurethane foam and composition for rigid polyurethane foam - Google Patents

Description

【００３１】
ポリオールＡ：ｍ−トルエンジアミン（ｍ−ＴＤＡ）／トリエタノールアミンを出発原料としてＰＯ（プロピレンオキサイド）を附加したポリオール（水酸基価４５０ｍｇＫＯＨ／ｇ）。
ポリオールＢ：上記ｍ−ＴＤＡをｏ−トルエンジアミン（ｏ−ＴＤＡ）に置き換えたポリオール（水酸基価４５０ｍｇＫＯＨ／ｇ）。
ポリオールＣ：シュガーを出発原料としてＰＯを附加したポリオール（水酸基価３８０ｍｇＫＯＨ／ｇ）。
ポリオールＤ：プロピレングリコールを出発原料としてＰＯを附加したポリオール（水酸基価５００ｍｇＫＯＨ／ｇ）。
ポリオールＥ：フタル酸とジエチレングリコールからのポリエステルポリオール（水酸基価４５０ｍｇＫＯＨ／ｇ）。
【００３２】
【発明の効果】
ポリオールの一部に、ｏ−トルエンジアミンを開始剤としてアルキレンオキサイドを付加重合させてなるポリエーテルポリオールを使用し、発泡剤として、シクロペンタン／イソペンタン混合物と水をブレンドすることによって、流動性の改良された硬質ポリウレタンフォームが得られる。流動性が改良されたことによって、フォームの低密度化が図れる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a rigid polyurethane foam and a composition for rigid polyurethane foam. Rigid polyurethane foam can be used as a heat insulating material for freezers, refrigerators, buildings, and the like.
[0002]
[Prior art]
Rigid polyurethane foam is widely used as a heat insulating material for a refrigerator-freezer, for example, a household refrigerator because it has a low product density, excellent heat insulation, and high mechanical strength.
As a foaming agent for producing this rigid polyurethane foam, a halogen-substituted chlorofluorocarbon (hereinafter referred to as CFC), particularly trichlorofluoromethane R11) has been conventionally used.
[0003]
However, since this R11 foaming agent contains halogen, there is a concern about the possibility of destroying the ozone layer in the stratosphere and environmental problems such as global warming. For the purpose of protecting the global environment, CFC production and consumption are regulated internationally.
CFC is banned in Japan by the end of 1995. As an alternative new blowing agent, hydrofluorochlorocarbon (HCFC) having a low ozone depletion coefficient is used. For example, HCFC141b (1,1-dichloro-1-fluoroethane), HCHC22 (chlorodifluoromethane), and HCFC142b (1-chloro-1,1-difluoroethane) have been introduced and applied as blowing agents.
[0004]
However, HCFC, which is an alternative chlorofluorocarbon, also contains chlorine atoms in the molecule, so it has little effect on the ozone layer, but it still has the property of destroying the ozone layer, so phased use reduction has been implemented. Therefore, from the viewpoint of protecting the global environment, the use of a foaming agent that does not affect the destruction of the ozone layer has been newly proposed. In some applications, hydrocarbons that do not contain any chlorine atoms and do not risk the destruction of the ozone layer. A blowing agent, such as cyclopentane, has been introduced and applied.
[0005]
[Problems to be solved by the invention]
However, cyclopentane is optimal as a foaming agent friendly to the global environment, but has some problems. The thermal conductivity of cyclopentane itself is high, and the heat insulation performance of the rigid polyurethane foam using cyclopentane is inferior to that using the conventional HCFC 141b, and improvement of the heat insulation characteristics is sought. In addition, cyclopentane itself is difficult to dissolve in conventionally used polyols, and there has been a problem in the stability of the premix when used in large quantities to reduce the density of the foam. Furthermore, since cyclopentane has a strong chemical attack property, it is known that the resin strength of the produced rigid foam tends to decrease.
[0006]
[Means for Solving the Problems]
In order to solve these problems and produce a heat insulating material with further excellent thermal conductivity, the use of a cyclopentane, isopentane and water blend as a foaming agent reduces the chemical attack of the foaming agent. By increasing the pressure, it is possible to reduce the density of the rigid foam that is the product. Also, by using a polyether polyol obtained by addition polymerization of alkylene oxide using o-toluenediamine as an initiator as a part of the polyol, a stable premix can be made even if a large amount of the blowing agent is dissolved in the polyol. As a result, the density of the foam can be reduced.
[0007]
The present invention relates to a process for producing a rigid polyurethane foam from a composition comprising an aromatic polyisocyanate, a polyol, a foaming agent, a catalyst, a foam stabilizer and other auxiliary agents, wherein a cyclopentane / isopentane mixture and water are used as the foaming agent. And a polyether polyol obtained by addition polymerization of alkylene oxide using o-toluenediamine as an initiator is used as a part of the polyol.
[0008]
The present invention
(1) Aromatic polyisocyanate (2) Polyol containing polyether polyol obtained by addition polymerization of alkylene oxide using o-toluenediamine as an initiator (3) Foaming agent comprising a blend of cyclopentane, isopentane and water (4 ) A rigid polyurethane foam composition comprising a catalyst, a foam stabilizer, and other auxiliaries is provided.
From this composition, a rigid polyurethane foam can be produced as a heat insulating material for a refrigerator or the like.
[0009]
As the aromatic polyisocyanate (1), polyisocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymethylene polyphenyl polyisocyanate (polymeric MDI), or modified polyisocyanates thereof may be used alone or in combination. Used.
Modified polyisocyanates, i.e. products obtained by partial chemical reaction of organic di- and / or polyisocyanates can be used. For example, di- and / or polyisocyanates containing ester, urea, burette, allophanate, carbodiimide, isocyanurate, and / or urethane groups can be used.
The amount of the aromatic polyisocyanate (1) in the composition may be 100 to 200 parts by weight, preferably 135 to 145 parts by weight with respect to 100 parts by weight of the polyol.
[0010]
The polyol (2), the foaming agent (3) and the auxiliary agent (4) constitute a polyol mixture.
The polyol (2) is preferably a polyether polyol and / or a polyester polyol.
Polyether polyol is, for example, ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, sucrose, bisphenol A and other polyhydric alcohols, or triethanolamine, ethylenediamine and other aliphatic amines, toluenediamine, It can be obtained by addition polymerization of alkylene oxide (for example, propylene oxide and / or ethylene oxide) using an aromatic amine such as methylenedianiline (MDA) as a reactive starting material.
[0011]
Polyether polyols can be prepared by known methods, for example, by anionic polymerization using alkali hydroxides such as potassium hydroxide and sodium hydroxide or alkali alcoholates such as potassium methylate and sodium methylate as a catalyst. It is obtained by adding alkylene oxide to a reactive starting material containing ˜8, preferably 3˜8. Alternatively, the polyether polyol can be obtained by adding alkylene oxide to a reactive starting material by cationic polymerization using a Lewis acid such as pentachloroantimony or boron fluoride etherate as a catalyst.
[0012]
Suitable alkylene oxides are tetrahydrofuran, ethylene oxide, 1,3-propylene oxide, 1,2- or 2,3-butylene oxide, 1,2-propylene oxide, styrene oxide, etc., especially ethylene oxide and 1,2 -Propylene oxide. These alkylene oxides can be used alone or as a mixture.
[0013]
Reactive starting materials (ie initiators) include polyhydric alcohols such as ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, sucrose, bisphenol A, etc., and alkanolamines, For example, ethanolamine, diethanolamine, N-methyl and N-ethylethanolamine, N-methyl and N-ethyldiethanolamine, triethanolamine and ammonia. Furthermore, aliphatic amines and aromatic amines can be used. For example, ethylenediamine, diethylenetriamine, 1,3-propylenediamine, 1,3- or 1,4-butylenediamine, 1,2-, 1,3-, 1,4-, 1,5-, and 1,6- Hexamethylenediamine, phenylenediamine, o-toluenediamine, m-toluenediamine, methylenedianiline (MDA), and polymethylenedianiline (P-MDA).
[0014]
As the polyester polyol, a polyester polyol such as polyethylene terephthalate produced from a polyvalent carboxylic acid (for example, dicarboxylic acid or tricarboxylic acid) and a polyhydric alcohol (for example, diol or triol) is used. Suitable polyester polyols can be prepared from dicarboxylic acids having 2 to 12 carbon atoms and preferably diols having 2 to 12 carbon atoms, particularly preferably 2 to 6 carbon atoms.
[0015]
Examples of the dicarboxylic acid include succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, phthalic acid, isophthalic acid and terephthalic acid. Instead of the free carboxylic acids, the corresponding carboxylic acid derivatives, for example dicarboxylic acid monoesters or diesters with alcohols having 1 to 4 carbon atoms, or dicarboxylic acid anhydrides can also be used.
[0016]
Examples of the diol include ethylene glycol, diethylene glycol, 1,2- or 1,3-propanediol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10- Decanediol can be used. As the triol, glycerin or trimethylolpropane can be used.
Lactone-based polyester polyols can also be used.
[0017]
The polyol preferably has a functional group number of 3 to 8, particularly preferably 3 to 6, and a hydroxyl value of 300 to 800 mgKOH / g, preferably 300 to 500 mgKOH / g.
[0018]
As a part of the polyol, a polyether polyol (2a) obtained by addition polymerization of alkylene oxide using o-toluenediamine (2,3-diaminotoluene and 3,4-diaminotoluene) as an initiator is used. The polyether polyol (2a) preferably has a hydroxyl value of 300 to 500 mgKOH / g. The amount of the polyether polyol (2a) is preferably 5 to 60% by weight, particularly 10 to 50% by weight, based on the polyol (2).
By using this polyether polyol (2a), a stable polyol premix can be made even if a large amount of the foaming agent (3) is dissolved.
[0019]
The blowing agent (3) comprises a blend of a pentane mixture composed of cyclopentane and isopentane and water. The pentane mixture preferably consists of 90-70% by weight cyclopentane and 10-30% by weight isopentane, more preferably 80% by weight cyclopentane and 20% by weight isopentane. By using a mixture of cyclopentane and isopentane, the chemical attack of the foaming agent is reduced and the resin strength of the foam is not reduced. On the other hand, since the vapor pressure of the foaming agent is increased and the fluidity of the reaction mixture is increased, the density of the rigid polyurethane foam as a product can be reduced. The pentane mixture used is 3 to 40 parts by weight, preferably 5 to 25 parts by weight with respect to 100 parts by weight of polyol, and water is 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight. use.
[0020]
A conventionally well-known thing can be used for auxiliary agent (4) (namely, catalyst, foam stabilizer, and other auxiliary agents). As the catalyst, an amine catalyst or a metal catalyst is used. As the amine catalyst, tertiary amines such as triethylenediamine, tetramethylhexamethylenediamine, pentamethyldiethylenetriamine, and methylmorpholine are used. As the metal catalyst, organic metal compounds such as stannous octoate, dibutyltin dilaurate and lead octylate are used. The amount of the catalyst is 0.01 to 5 parts by weight, particularly preferably 0.05 to 2.5 parts by weight, based on 100 parts by weight of the polyol.
[0021]
As the foam stabilizer, a normal organic silicon compound or the like can be used. The amount of the foam stabilizer is 0 to 5 parts by weight, particularly preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the polyol.
In the present invention, as other auxiliaries, suitable amounts of foam stabilizer, foam control agent, filler, dye, pigment, flame retardant, and hydrolysis inhibitor can be used.
[0022]
In the present invention, the isocyanate index [(ratio of equivalent of isocyanate group of polyisocyanate (1) to equivalent of active hydrogen in polyol mixture) × 100] is preferably 90 to 150, particularly 105 to 115.
[0023]
The rigid polyurethane foam can be produced by a known foaming machine by a batch method or a continuous method, by a prepolymer method or a one-shot method. As a particularly preferred method, a two-component method (component A: polyisocyanate (1), component B: polyol premix (polyol mixture obtained by mixing polyol (2), blowing agent (3) and auxiliary agent (4)) )), There is a method of processing. Component A and Component B are mixed at a temperature of 5 to 50 ° C. (especially 15 to 35 ° C.), injected into a mold adjusted to a temperature of 20 to 70 ° C. (especially 35 to 45 ° C.), foamed, and rigid polyurethane foam Get.
[0024]
Preferred embodiments of the invention
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
[0025]
Example 1
For 50 parts by weight of polyol B, 40 parts by weight of polyol C, and 10 parts by weight of polyol D, an amine catalyst (1.2 parts by weight of tetramethylhexamethylenediamine + 0.7 parts by weight of pentamethyldiethylenetriamine) and a foam stabilizer (SF2929, Toray Dow) A polyol mixture was prepared by mixing 2 parts by weight of Corning) and 2 parts by weight of water. A final polyol mixture was prepared by mixing 13 parts by weight of cyclopentane as a blowing agent and 3 parts by weight of isopentane with the polyol mixture. Polyol mixture and polymeric MDI (NCO content: 31.5%) 141 parts by weight with mixer (isocyanate index: 110), was bubbled. The temperature of the urethane mixture at that time was adjusted to 20 ° C. The urethane mixture was stirred with a mixer and poured into a 600 × 400 × 50 mm aluminum mold adjusted to 45 ° C., and after 7 minutes, the molded product was removed from the mold to obtain a rigid polyurethane foam.
[0026]
Example 2
A rigid polyurethane foam was obtained in the same manner as in Example 1 except that the polyol and the foaming agent having the composition shown in Table 1 were used.
[0027]
Comparative Example 1
50 parts by weight of polyol A, 40 parts by weight of polyol C, 10 parts by weight of polyol D, amine catalyst (1.2 parts by weight of tetramethylhexamethylenediamine + 0.7 parts by weight of pentamethyldiethylenetriamine), 2 parts of foam stabilizer (SF2929) A polyol mixed solution was prepared by mixing 2 parts by weight of water and 2 parts by weight of water. The final polyol mixture was prepared by mixing 12 parts by weight of the blowing agent cyclopentane with the polyol mixture. The polyol mixture and 141 parts by weight of polymeric MDI (NCO content: 31.5%) were mixed with a mixer (isocyanate index: 110) and foamed. The temperature of the urethane mixture at that time was adjusted to 20 ° C. The urethane mixture was stirred with a mixer and poured into a 600 × 400 × 50 mm aluminum mold adjusted to 45 ° C., and after 7 minutes, the molded product was removed from the mold to obtain a rigid polyurethane foam.
[0028]
Comparative Examples 2 and 3
A rigid polyurethane foam was obtained in the same manner as in Comparative Example 1 except that the polyol and the foaming agent having the composition shown in Table 1 were used.
[0029]
The physical properties of the molded articles obtained in Examples 1-2 and Comparative Examples 1-3 were measured as follows, and the results obtained are shown in Table 1.
Compressive strength A 50 mm cubic sample taken from the core of the foam was compressed in the direction perpendicular to the flow (10 mm / min head speed), and the stress was measured when the displacement reached 10%.
Core foam density The density of the center portion of the foam, excluding the surface portion, was measured.
Thermal conductivity A 200x200x25 mm sample cut out from the core of the foam was measured with a thermal conductivity measuring device (Auto Lambda) manufactured by Eihiro Seiki.
Pentane compatibility 100 g of the polyol mixture (excluding the blowing agent) was taken into a test tube equipped with a screw stopper, and a predetermined amount of pentane was added and mixed. Subsequently, it left still and observed the external appearance. If it was transparent, it was determined that it was dissolved.
Rigid polyurethane was packed into a mold having a flowability of 200 × 50 × 2000 mm and adjusted to 40 ° C. Weighed when a little overflowed to the above size. The lighter one has higher fluidity.
[0030]
[Table 1]

[0031]
Polyol A: Polyol (hydroxyl value 450 mgKOH / g) to which PO (propylene oxide) was added starting from m-toluenediamine (m-TDA) / triethanolamine.
Polyol B: Polyol (hydroxyl value 450 mgKOH / g) in which the m-TDA is replaced with o-toluenediamine (o-TDA).
Polyol C: Polyol added with PO using sugar as a starting material (hydroxyl value 380 mgKOH / g).
Polyol D: Polyol added with PO using propylene glycol as a starting material (hydroxyl value 500 mgKOH / g).
Polyol E: Polyester polyol from phthalic acid and diethylene glycol (hydroxyl value 450 mgKOH / g).
[0032]
【The invention's effect】
A part of the polyol is a polyether polyol obtained by addition polymerization of alkylene oxide using o-toluenediamine as an initiator, and a fluidity is improved by blending a cyclopentane / isopentane mixture and water as a blowing agent. A rigid polyurethane foam is obtained. By improving the fluidity, the density of the foam can be reduced.

Claims (2)

A process for producing a rigid polyurethane foam from a composition comprising an aromatic polyisocyanate, a polyol, a blowing agent, a catalyst, a foam stabilizer and other auxiliary agents,
The blowing agent is a blend of 90-70 wt% cyclopentane and 10-30 wt% isopentane and water ;
The amount of cyclopentane / isopentane mixture is 5-25 parts by weight per 100 parts by weight of polyol,
The polyol has 3 to 6 functional groups,
A polyether polyol having a hydroxyl value of 300 to 500 mgKOH / g obtained by addition polymerization of alkylene oxide using o-toluenediamine as an initiator is used in a part of the polyol, based on the polyol. Manufacturing method of rigid polyurethane foam. (1) Aromatic polyisocyanate (2) Polyether polyol having a hydroxyl value of 300 to 500 mgKOH / g obtained by addition polymerization of alkylene oxide using o-toluenediamine as an initiator is contained in an amount of 10 to 50% by weight based on the polyol. Polyol having 3 to 6 functional groups (3) A blend of 90 to 70% by weight of cyclopentane and 10 to 30% by weight of isopentane and water, the amount of cyclopentane / isopentane mixture being 100 parts by weight of polyol A composition for rigid polyurethane foam comprising 5 to 25 parts by weight of a foaming agent (4) catalyst, a foam stabilizer and other auxiliaries.