JP2008260841A - Polyisocyanate composition for producing rigid polyurethane foam having closed cells, and method for producing rigid polyurethane foam having closed cells by using the composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyisocyanate composition for producing a rigid polyurethane foam having closed cells, having extremely superior storage stability, capable of imparting thermal conductivity and excellent mechanical properties (dimensional stability or the like) to the resultant rigid polyurethane foam having closed cells, and suitable especially when using a hydrocarbon as the foaming agent, and to provide a method for producing the rigid polyurethane foam having closed cells by using the polyisocyanate composition. <P>SOLUTION: The polyisocyanate composition is constituted of a polymeric MDI and an ethylene glycol monoether having <150 molecular weight. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polyisocyanate composition for producing a rigid polyurethane foam having closed cells, and a method for producing a rigid polyurethane foam having closed cells using the composition. More specifically, a polyisocyanate composition for producing rigid polyurethane foam having closed cells, which is excellent in low thermal conductivity and capable of obtaining good foam properties while being closed cells, and the polyisocyanate composition. The present invention relates to a method for producing a rigid polyurethane foam having closed cells. In the present invention, “rigid polyurethane foam” is a concept including “isocyanurate-modified polyurethane foam” unless otherwise specified. Further, “having closed cells” in the present invention means that the closed cell ratio based on ASTM D2856 is 75% or more (including 75%).

  Conventionally, rigid polyurethane foam has been widely used as a heat insulating material for refrigerators, refrigerated warehouses, building materials and the like, and for spray applications.

  As the polyisocyanate for producing the rigid polyurethane foam, polymeric MDI including diphenylmethane diisocyanate (hereinafter abbreviated as “MDI”) and an MDI-based polynuclear condensate (polyphenylene polymethylene polyisocyanate) is used.

  On the other hand, (hydro) chlorofluorocarbons such as 1,1-dichloro-1-fluoroethane which have been widely used in the past from the viewpoint of preventing destruction of the ozone layer as a foaming agent for producing a rigid polyurethane foam. Instead, hydrocarbons such as n-pentane, cyclopentane, cyclohexane, or mixtures thereof are beginning to be used.

  In the field of using rigid polyurethane foam, it is required that the rigid polyurethane foam itself has low thermal conductivity. Rigid polyurethane foam applied in such a field is required to be closed cells instead of open cells.

  In this case, when hydrocarbon is used as the foaming agent, the thermal conductivity of the gas itself vaporized and taken into the bubbles as a foaming agent tends to be higher than that of the foaming agents used so far. For this reason, it is necessary to consider reducing the thermal conductivity of the obtained rigid polyurethane foam itself.

  As a technique for solving such a problem, for example, (1) an isocyanate group terminal obtained by reacting polymeric MDI with at least one linear, branched or cyclic, saturated or olefinically unsaturated low molecular weight monoalcohol. There have been proposed a method using a prepolymer (see Patent Document 1) and (2) a method using an isocyanate group-terminated prepolymer obtained by reacting at least one polyester-polyol with a polymeric MDI (see Patent Document 2).

  However, in the method according to the above (1) or (2), since the obtained isocyanate group-terminated prepolymer itself has a high viscosity, a high performance mixing head is required for obtaining a rigid polyurethane foam. Alternatively, there has been a problem of expensive investment in equipment and an increase in production cost, such as the necessity of heating the isocyanate group-terminated prepolymer more than necessary in order to obtain a good mixing state in the mixing head.

JP 7-278256 A JP-A-8-231672

  The present invention has been made based on the background as described above.

  The first object of the present invention is to have a low viscosity (specifically, the viscosity at 25 ° C. is in the range of 50 to 500 mPa · s) such that a sufficiently good mixing property can be obtained with a conventionally used mixing head. In addition, a polyisocyanate composition for producing a rigid polyurethane foam having closed cells, which can achieve low thermal conductivity in the obtained rigid polyurethane foam, and a rigid polyurethane foam having closed cells using the composition. It is to provide a manufacturing method.

  The second object of the present invention is to provide a rigid polyurethane foam having a desired mechanical property equal to or higher than that of a rigid polyurethane foam having closed cells conventionally used in various fields. It is another object of the present invention to provide a polyisocyanate composition for producing a rigid polyurethane foam having the above, and a method for producing a rigid polyurethane foam having closed cells using the composition.

  The third object of the present invention is to provide closed cells that can achieve both the first object and the second object, especially when using hydrocarbons that have recently been used as a foaming agent. It is an object of the present invention to provide a polyisocyanate composition for producing a rigid polyurethane foam and a method for producing a rigid polyurethane foam having closed cells using the composition.

  In order to solve these series of problems (to achieve the object), the present inventors have conducted intensive studies, and as a result, the use of a specific polyisocyanate composition for producing a rigid polyurethane foam is a very means for solving the problem. As a result, the present invention was found.

  That is, the present invention is as follows (1) to (4).

(1) (A1) 20 to 80% by mass of the diphenylmethane diisocyanate isomer mixture (a1d), 80 to 20% by mass of a trinuclear or higher diphenylmethane diisocyanate polynuclear condensate (a1p) (provided that (a1d) + (a1p) ) = Polymeric MDI in which (A1) is 100% by mass), and (A2) ethylene glycol monoether having a molecular weight of less than 150,
A rigid polyurethane having closed cells, which is obtained by mixing and reacting, and having a viscosity at 25 ° C. of 50 to 500 mPa · s and an isocyanate group content of 28.0 to 32.0% by mass Polyisocyanate composition for foam production.

(2) It is obtained by reacting the polyisocyanate composition according to (1) with a polyol (B) in the presence of a foaming agent (C), a catalyst (D) and a foam stabilizer (E). A method for producing a rigid polyurethane foam having closed cells.

(3) The method for producing a rigid polyurethane foam having closed cells according to (2), wherein hydrocarbon (C1) and water (C2) are used together as the foaming agent (C).

(4) The method for producing a rigid polyurethane foam having closed cells according to (2) or (3), wherein the hydrocarbon (C1) used as the foaming agent (C) is cyclopentane.

  The polyisocyanate composition for producing a rigid polyurethane foam having closed cells of the present invention has a low viscosity (specifically, a viscosity at 50 ° C. is 50 to 50 ° C.) so that a sufficiently good mixing property can be obtained even with a conventionally used mixing head. Therefore, a conventional mixing head for producing a rigid polyurethane foam having closed cells can be applied.

  The polyisocyanate composition for producing a rigid polyurethane foam having closed cells according to the present invention and the method for producing a rigid polyurethane foam having closed cells improve the thermal conductivity desired for the obtained rigid polyurethane foam having closed cells ( It is possible to achieve low thermal conductivity.

  Further, according to the polyisocyanate composition for producing a rigid polyurethane foam having closed cells of the present invention and a method for producing a rigid polyurethane foam having closed cells, it is equivalent to a rigid polyurethane foam having closed cells conventionally used in various fields. It is possible to obtain a rigid polyurethane foam having further desired mechanical properties.

  A series of these excellent effects is obtained by the formulation for producing rigid polyurethane foam having closed cells using hydrocarbon and water as a blowing agent, particularly for producing rigid polyurethane foam having closed cells using cyclopentane and water as a blowing agent. Can be provided.

  The present invention will be described in further detail.

  The polyisocyanate composition of the present invention comprises (A1) 20 to 80% by mass of a diphenylmethane diisocyanate isomer mixture (hereinafter abbreviated as “MDI”) (a1d), a trinuclear or more diphenylmethane diisocyanate polynuclear condensate (hereinafter “MDI”). Abbreviated as “polynuclear condensate”) (a1p) of 80 to 20% by mass (provided that (a1d) + (a1p) = (A1) = 100% by mass)) and (A2) ethylene having a molecular weight of less than 150 Consists of glycol monoether.

<Polymeric MDI (A1)>
The polymeric MDI (A1) constituting the polyisocyanate composition of the present invention is a mixture comprising 20 to 80% by mass of MDI (a1d) and 80 to 20% by mass of an MDI-based multinuclear condensate (a1p). The polymeric MDI may also be referred to as “polyphenylene polymethylene polyisocyanate” or “crude MDI”. In addition, the sum total of MDI (a1d) and MDI type | system | group multinuclear condensate (a1p) is 100 mass% as polymeric MDI (A1).

  Polymeric MDI (A1) can be obtained by converting the amino group of a condensation mixture (polyamine) obtained by the condensation reaction of aniline and formalin to an isocyanate group by phosgenation or the like. By changing the reaction conditions, the composition (nuclear distribution and isomer composition ratio) of the finally obtained polymeric MDI can be controlled.

  The polymeric MDI (A1) used in the present invention is a reaction solution such as a reaction solution after conversion to an isocyanate group, removal of the solvent from the reaction solution, and a bottom solution obtained by distilling and separating part of MDI. It may be a mixture of several different types. Moreover, what mixed MDI (a1d) with the commercially available polymeric MDI may be used.

  The proportion of MDI (a1d) in the polymeric MDI (A1) is in the range of 20 to 80% by mass, preferably in the range of 25 to 75% by mass, in particular, the storage stability in the liquid state in the polymeric MDI (A1), Moreover, it is especially preferable that it is the range of 26-70 mass% from a viewpoint that the favorable workability | operativity at the time of rigid polyurethane foam formation is comprised. Here, the ratio of MDI (a1d) is a ratio obtained from the peak area ratio of MDI by GPC (gel permeation chromatography). When the ratio of MDI (a1d) in the polymeric MDI (A1) exceeds 80% by mass, there is a possibility that defects may occur in the storage stability of the polymeric MDI, such as precipitation of crystals due to the MDI (a1d). It tends to be higher. On the other hand, when this ratio is less than 20% by mass, the viscosity of the polymeric MDI tends to be excessively high, and there is a high possibility that problems may occur in terms of workability such as mixing failure.

  MDI (a1d), which is a binuclear body, is composed of three isomers of 4,4′-MDI, 2,2′-MDI, and 2,4′-MDI. In the present invention, the composition ratio of these isomers is not particularly limited, but from the viewpoint of having excellent storage stability (no crystals or the like are deposited) even under severe low temperature conditions such as −20 ° C. , 4,4'-MDI content is preferably in the range of 60 to 100%, from the viewpoint that the desired mechanical properties can be reliably obtained in the resulting rigid polyurethane foam, 95-100% It is more preferable that the value be within the range (in particular, the level is particularly close to 100%). The composition ratio of isomers can be determined from a calibration curve based on the area percentage of each peak obtained by GC (gas chromatography).

  The average number of functional groups of the polymeric MDI (A1) is preferably 2.1 or more (including 2.1), more preferably in the range of 2.2 to 3.1.

  The isocyanate group content of the polymeric MDI (A1) is preferably in the range of 27 to 33% by mass, and more preferably in the range of 28.5 to 32.5% by mass.

  The acidity of the polymeric MDI (A1) is preferably in the range of 0.001 to 0.2% by mass, and more preferably in the range of 0.003 to 0.15% by mass. Thereby, the storage stability and suitable reactivity of the polyisocyanate composition obtained are ensured. The “acidity” means a value obtained by converting an acid component that reacts with alcohol at room temperature and liberated into hydrogen chloride, and is measured according to JIS K-1603.

  In addition, polymeric MDI (A1) which comprises the polyisocyanate composition of this invention is in a series of structural requirements essential in the polyisocyanate composition of this invention mentioned later, when the whole polyisocyanate composition is 100 mass%. In consideration of the ratio of introduction (and thus desired performances and effects obtained by introduction of each constituent element), it is preferably used in the range of 92.0 to 99.5% by mass.

<Ethylene glycol monoether (A2) having a molecular weight of less than 150>
Examples of the ethylene glycol monoether having a molecular weight of less than 150 (compounds generally referred to as “cellosolve”) (A2) constituting the polyisocyanate composition of the present invention include ethylene glycol monomethyl ether (β-oxyethyl methyl ether). , Ethylene glycol monoethyl ether (β-oxyethyl ether), ethylene glycol monopropyl ether, ethylene glycol monoalkyl ether such as ethylene glycol monobutyl ether, ethylene glycol monoaryl ether such as ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether And monoaralkyl ethers such as

  In the present invention, the isocyanate group content is preferably in the range of 28.0 to 32.0% by mass so that the mechanical properties of the obtained rigid polyurethane foam having closed cells are good. The molecular weight of the polyisocyanate composition obtained is preferably less than 150 from the viewpoint that it can be modified within a range of 50 to 500 mPa · s at 25 ° C. and low thermal conductivity. As ethylene glycol monoether (A2), it is preferable to use either ethylene glycol monomethyl ether or ethylene glycol monoethyl ether, or a mixture of both, and among these, the series of viewpoints can be most reflected. Therefore, ethylene glycol monomethyl ether (also known as And more preferably selected and used methyl cellosolve ").

  The ethylene glycol monoether (A2) having a molecular weight of less than 150 constituting the polyisocyanate composition of the present invention is 0.5 to 8 from the same viewpoint as described above when the entire polyisocyanate composition is 100% by mass. It is preferably used within the range of 0.0 mass%.

  In the polyisocyanate composition of the present invention, the ethylene glycol monoether (A2) having a molecular weight of less than 150 may exist in a form reacted with a part of the isocyanate group in the polymeric MDI (A1). You may exist in the form mixed uniformly, without reacting with an isocyanate group.

<Other isocyanate compounds>
In the polyisocyanate composition of the present invention, the above-mentioned polymeric MDI (A1) is essential, but if necessary, an isocyanate compound other than the essential isocyanate compound (hereinafter abbreviated as “other isocyanate compound”). It may be contained.

  As other isocyanate compounds, urethanized products obtained by reacting polymeric MDI (or only MDI) with active hydrogen group-containing compounds (the above-mentioned isocyanate groups in ethylene glycol monoether (A2) and polymeric MDI (A1)) Except those which exist in a form in which a part thereof is reacted.), Urea compound, allophanate compound, biuret compound, carbodiimidide compound, uretoniminate compound, uretdione compound, isocyanurate compound; 2,4-tolylene diisocyanate, 2,6- Aromatic diisodies such as tolylene diisocyanate, xylene-1,4-diisocyanate, xylene-1,3-diisocyanate, tetramethylxylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate Anates; aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, 3-methyl-1,5-pentane diisocyanate, lysine diisocyanate; fats such as isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate Examples thereof include cyclic diisocyanates. In addition, urethanized products, urea compounds, allophanate compounds, biuret compounds, carbodiimide compounds, uretoniminate compounds, uretdione compounds, isocyanurate compounds, etc. obtained by reacting these polymeric substances and these isocyanates with active hydrogen group-containing compounds. It can also be used. These isocyanate compounds can be used alone or in combination of two or more.

<Optional component>
The polyisocyanate composition of the present invention may contain various optional components as long as the effect is not impaired. As such optional components, all conventionally known substances (such as additives) can be used as those contained in the polyisocyanate composition for producing a rigid polyurethane foam.

<Polyisocyanate composition>
The isocyanate group content in the polyisocyanate composition of the present invention is in the range of 28.0 to 32.0% by mass, preferably 28.2 to 29.5% by mass from the viewpoint of achieving the above effects. %, In particular, from the viewpoint of ensuring that the rigid polyurethane foam obtained by using the polyisocyanate composition of the present invention has the desired good thermal conductivity and mechanical properties, 28.4 to 29. A range of 0% by mass is particularly preferable. When the isocyanate group content is less than 28.0% by mass, the viscosity may be high, resulting in inferior uniform mixing, and it may be difficult to obtain good mechanical properties due to the small number of isocyanate groups contributing to the reaction. There is. Moreover, when it exceeds 32.0 mass%, it may become difficult to obtain the favorable heat conductivity desired for the rigid polyurethane foam obtained in the present invention.

  Further, the viscosity (25 ° C.) of the polyisocyanate composition of the present invention is set in the range of 50 to 500 mPa · s from the viewpoint of achieving the above-mentioned effect, preferably in the range of 100 to 400 mPa · s, Above all, it can be easily applied to existing production equipment such as a conventionally known mixing head (for example, heating is increased more than necessary (= increasing production cost) to ensure uniform mixing with other components to lower the viscosity). From the viewpoint of being excellent in uniform mixing with the polyols and the like described later, it is particularly preferably in the range of 150 to 350 mPa · s.

  The polyisocyanate composition of the present invention is particularly suitably used for producing a rigid polyurethane foam having closed cells using hydrocarbon (C1) and water (C2) as foaming agents.

<Method for producing rigid polyurethane foam>
In the method for producing a rigid polyurethane foam having closed cells according to the present invention, the polyisocyanate composition and the polyol (B) are added in the presence of a foaming agent (C), a catalyst (D) and a foam stabilizer (E). In which the polyisocyanate composition comprises:
(A1) Diphenylmethane diisocyanate isomer mixture (a1d) is 20 to 80% by mass, triphenyl or higher diphenylmethane diisocyanate polynuclear condensate (a1p) is 80 to 20% by mass (provided that (a1d) + (a1p) = ( A1) 100% by mass) polymeric MDI, and (A2) an ethylene glycol monoether (A2) having a molecular weight of less than 150,
Closed cell, characterized in that the viscosity at 25 ° C. obtained by reacting and mixing is 50 to 500 mPa · s, and preferably the isocyanate group content is 28.0 to 32.0% by mass. It is characterized in that it is a polyisocyanate composition for producing rigid polyurethane foam.

<Polyol (B)>
As the “polyol (B)” used in the production method of the present invention, it is preferable to use at least one of the following three types of polyols [polyols (b1) to (b3)], and two or more types are used. More preferably.

  When only one of polyol (b1) and polyol (b3) is used, the formed rigid polyurethane foam may not have sufficient mechanical strength. Moreover, the polyol (B) consisting only of the polyol (b2) has an excessive viscosity and tends to be inferior in workability.

<Polyol (b1)>
Initiator of alkanolamines such as monoethanolamine, diethanolamine and triethanolamine, one or a mixture of two or more amine compounds such as tolylenediamine, ethylenediamine, diethylenetriamine, ammonia, aniline, xylylenediamine and diaminodiphenylmethane As a polyether polyol obtained by addition reaction of alkylene oxide such as ethylene oxide and propylene oxide, the hydroxyl value is in the range of 50 to 1,000 mgKOH / g, preferably in the range of 100 to 900 mgKOH / g. Furthermore, a polyhydric alcohol used for obtaining the polyol (b2) and the polyol (b3) can be used in combination as an initiator.

<Polyol (b2)>
(1) Ethylene glycol, propanediol, butanediol, diethylene glycol, dipropylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentyl glycol, 3-methyl-1,5-pentanediol, glycerin , Trimethylolpropane, pentaerythritol, methyl glucoside, sorbitol, mannitol, dulcitol, a mixture of one or more polyhydric alcohols such as sucrose, adipic acid, malonic acid, fumaric acid, succinic acid, tartaric acid, At least two or more carboxyl groups (or derived from carboxyl groups, such as oxalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, 1,4-cyclohexanedicarboxylic acid, etc. A hydroxyl group value of 50 to 800 mgKOH / g, preferably 100 to 700 mgKOH / g, obtained by producing by a known method using one or a mixture of two or more compounds having Polyester polyol.
(2) A polyester polyol obtained by ring-opening polymerization of lactones (for example, ε-caprolactone).
(3) A recovered polyester obtained by decomposing a polyester polyol and a polyester molded product.

<Polyol (b3)>
Ethylene glycol, propanediol, butanediol, diethylene glycol, dipropylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentyl glycol, 3-methyl-1,5-pentanediol, glycerin, trimethylol Starting with a polyhydric alcohol having 2 to 8 hydroxyl groups in one molecule, such as propane, pentaerythritol, methyl glucoside, sorbitol, mannitol, dulcitol, and sucrose, an alkylene oxide such as ethylene oxide and propylene oxide A polyester having a hydroxyl value in the range of 50 to 1,000 mgKOH / g, preferably in the range of 100 to 900 mgKOH / g, obtained by addition reaction. Tell polyol.

  In each of the polyols (b1) to (b3), when the hydroxyl value is not less than a certain value (lower limit value), sufficient mechanical strength can be imparted to the formed rigid polyurethane foam. Moreover, embrittlement of the hard polyurethane foam formed can be suppressed because a hydroxyl value is below a fixed value (upper limit).

  The average number of functional groups of the polyol (b1) is preferably in the range of 2 to 6, and more preferably in the range of 3 to 6.

  The average number of functional groups of the polyol (b2) is preferably in the range of 2 to 4, more preferably in the range of 2 to 3.

  The average functional group number of the polyol (b3) is preferably in the range of 2 to 8, more preferably in the range of 3 to 8.

  In each of the polyols (b1) to (b3), when the average number of functional groups is a certain number (lower limit) or more, sufficient mechanical strength can be imparted to the formed rigid polyurethane foam. Moreover, embrittlement of the rigid polyurethane foam formed can be suppressed because an average functional group number is below a fixed number (upper limit).

  When using a polyol (b1), it is preferable that the ratio of the polyol (b1) to a polyol (B) exists in the range of 5-40 mass%.

  When using a polyol (b2), it is preferable that the ratio of the polyol (b2) to a polyol (B) exists in the range of 10-90 mass%.

  When using a polyol (b3), it is preferable that the ratio of the polyol (b3) to a polyol (B) exists in the range of 10-90 mass%.

  The total proportion of polyol (b1), polyol (b2), and polyol (b3) in the polyol (B) is preferably 80% by mass or more (including 80% by mass).

  When the content ratio of the polyol (b1) is excessive, the activity becomes too high, and there is a risk of causing molding defects such as voids.

  When the content ratio of the polyol (b2) is excessive, the viscosity of the polyol (B) increases, and the liquid flowability and filling property of the foam tend to deteriorate.

  When the content ratio of the polyol (b3) is excessive, the mechanical strength of the formed rigid polyurethane foam tends to decrease.

  Polyols other than polyols (b1) to (b3) constituting the polyol (B) (hereinafter abbreviated as other polyols) include ethylene glycol, diethylene glycol, and polypropylene glycol having a hydroxyl value in the range of 50 to 150 mgKOH / g. It can be mentioned as a suitable thing.

  By using at least one selected from ethylene glycol, diethylene glycol, and polypropylene glycol having a hydroxyl value in the range of 50 to 150 mgKOH / g, the viscosity of the polyol (B) can be lowered.

  Moreover, you may use a polymer polyol as another polyol which comprises a polyol (B). This polymer polyol is based on the above-described polyether polyol or polyester polyol, and is obtained by introducing a styrene or acrylonitrile vinyl polymer or a polymer obtained from an active hydrogen group-containing compound and polyisocyanate as graft polymerization or filler. The polymer content in the polymer polyol is preferably 1 to 20% by mass.

  The viscosity (25 ° C.) of the polyol (B) is preferably 2,000 mPa · s or less (including 2,000 mPa · s), more preferably in the range of 100 to 1,800 mPa · s. When the viscosity exceeds the upper limit, workability particularly in winter is reduced.

<Foaming agent (C)>
The “foaming agent (C)” used in the production method of the present invention is not particularly limited as long as it is a conventionally known foaming agent used for obtaining a rigid polyurethane foam having closed cells, and any of them can be used. is there.

  In the production method of the present invention, in consideration of the recent prevention of ozone layer destruction, hydrocarbon (linear saturated hydrocarbon compound which may have a side chain or cyclic saturated) is used as the foaming agent (C). Hydrocarbon compound) (C1), for example, hydrocarbon (C1) such as normal pentane, isopentane, cyclopentane, cyclohexane, or a mixture thereof and water (C2) are preferably used in combination, and particularly, good gas heat From the viewpoint of obtaining conductivity and having a relatively high flash point, it is particularly preferable to use cyclopentane and water in combination. In this case, the addition amount of the foaming agent (C) is within the range of 1 to 50% by mass when the hydrocarbon (C1) is 100% by mass of the polyol (B), and the water (C2) is polyol (B ) Is 100% by mass, it is preferably used in the range of 0.5 to 5.0% by mass.

  In the present invention, the foaming agent (C) is a combination of hydrocarbon (C1) and water (C2), specifically, the main foaming agent is hydrocarbon (C1), and the secondary foaming agent is water (C2). The form used together as the most exerts the effect desired for the rigid polyurethane foam obtained by the production method of the present invention. Here, “primary foaming agent” and “secondary foaming agent” are some of the mass parts used, meaning that “primary foaming agent” is more in mass parts than “secondary foaming agent”. It is.

  In addition, in the manufacturing method of this invention, if it exists in the range which can maintain the performance (for example, low thermal conductivity and dimensional stability (small normal temperature shrinkage)) desired for the rigid polyurethane foam obtained, a foaming agent ( It is also possible to use hydrofluoroether as C) alone or in combination with hydrocarbon (C1) and / or water (C2).

As the hydrofluoroether, those conventionally known as hydrofluoroethers, specifically, for example, HFE-254pc (CHF ₂ CF ₂ OCH ₃ ), CF ₃ CHFOCF ₃ (HFE-227me), CF ₃ CHFOCHF ₂ (HFE- _{236me), CF 3 CH 2 OCF} 3 (HFE-236mf), CHF 2 CF 2 OCHF 2 (HFE-236pc), CF 3 CF 2 OCH 3 (HFE-245mc), CF 3 CH 2 OCHF 2 (HFE-245mf) , CF ₃ CF ₂ CF ₂ OCH ₃ (HFE-247mcc), CF ₃ CF ₂ OCH ₂ CF ₃ (HFE-338mc-f), (CF ₃ ) ₂ CFOCH ₃ (HFE-347mmy), CHF ₂ CF ₂ OCH ₂ F (HFE-245pc), C _{H 2 FCF 2 OCHF 2 (HFE} -245qc), CF 3 CF 2 CH 2 OCHF 2 (HFE-347mcf), CF 3 CHFCF 2 OCH 3 (HFE-356mec), CHF 2 CF 2 CF 2 OCH 3 (HFE-356pcc _{), CHF 2 CF 2 CH 2} OCHF 2 (HFE-356pcf), CHF 2 CF 2 OCH 2 CF 3 (HFE-347pc-f), CF 3 CH 2 OCH 2 CF 3 (HFE-356mf-f), CH 2 FCF ₂ OCH ₂ CF ₃ (HFE-356qc-f), (CF ₃ ) ₂ CHOCH ₃ (HFE-356 mmz), and the like can be given. In the production method of the present invention, any one of these may be selected and used alone or in combination with hydrocarbon (C1) and / or water (C2), or two of these. The above may be used in combination with a hydrofluoroether mixture, or hydrocarbon (C1) and / or water (C2).

<Catalyst (D)>
As the “catalyst (D)” used in the production method of the present invention, a known catalyst usually used for urethane foaming can be used. For example, as a urethanization catalyst, N-methylimidazole, trimethylaminoethylpiperazine, tripropylamine, tetramethylhexamethylenediamine, triethylenediamine, triethylamine, N-methylmorpholine, dimethylcyclohexylamine, dibutyltin diacetate, dibutyltin dilaurate, etc. And metal complex compounds such as acetylacetone metal salts. Trimerization catalysts include 2,4,6-tris (dimethylaminomethyl) phenol, triazines such as 1,3,5-tris (dimethylaminopropyl) hexahydro-s-triazine, 2,4-bis (dimethylamino) Methyl) phenol, amine compounds such as potassium 2-ethylhexanoate, sodium 2-ethylhexanoate, potassium acetate, sodium acetate, 2-ethylaziridine and the like, and quaternary compounds such as tertiary amine carboxylates Examples include ammonium compounds, lead compounds such as diazabicycloundecene, lead naphthenate and lead octylate, alcoholate compounds such as sodium methoxide, phenolate compounds such as potassium phenoxide, and the like. These catalysts can be used alone or in combination of two or more.

  The amount of the catalyst (D) used is suitably an amount in the range of 0.01 to 15% by mass when the polyol (B) is 100% by mass.

<Foam stabilizer (E)>
As the foam stabilizer (E) used in the production method of the present invention, all conventionally known foam stabilizers for rigid polyurethane foam (dimethylpolysiloxane and polysiloxane-polyether copolymer) may be used. it can. Specific examples include known silicone surfactants such as L-5340, L-5420, L-5421, L-5740, L-580, SZ-1142, and SZ-1642 manufactured by Toray Dow Corning. , SZ-1605, SZ-1649, SZ-1919, SZ-1675, SZ-1720, SZ-1725, SH-190, SH-192, SH-193, SF-2945F, SF-2940F, SF-2936F, SF -2938F, SRX-294A, F-305, F-341, F-343, F-374, F-345, F-348 manufactured by Shin-Etsu Chemical Co., Ltd., B-8404, B-8407, B- manufactured by Goldschmidt 8465, B-8444, B-8467, B-8433, B-8466, B-8870, B-8450, B-8460, etc. It is below.

  In the production method of the present invention, it is preferable to use a polysiloxane-polyether copolymer containing a hydroxyl group (hereinafter referred to as “hydroxyl group-containing silicone”) as part or all of the foam stabilizer (E). .

  The hydroxyl group-containing silicone is a block copolymer having a dimethylpolysiloxane structure and a polyoxyalkylene structure (polyether structure), and is a compound having a hydroxyl group in the molecular structure.

  The average number of functional groups (average number of hydroxyl groups in one molecule) of the hydroxyl group-containing silicone is preferably in the range of 1 to 10, more preferably in the range of 1 to 5, particularly preferably in the range of 1 to 2. It is assumed to be inside.

  The number average molecular weight of the hydroxyl group-containing silicone is preferably in the range of 500 to 20,000, more preferably in the range of 1,000 to 18,000. Those having an excessive number average molecular weight have high viscosity and poor handleability.

  The hydroxyl value of the hydroxyl group-containing silicone is preferably in the range of 3 to 300 mgKOH / g, and more preferably in the range of 5 to 150 mgKOH / g.

  The amount of the foam stabilizer (E) used in the present invention is suitably in the range of 0.1 to 5% by mass when the polyol (B) is 100% by mass.

  In the production method of the present invention, an additive can be used (the polyisocyanate composition of the present invention and the polyol (B) are reacted in the presence of the additive). Examples of the additives include plasticizers, fillers, colorants, flame retardants, organic or inorganic fillers, antioxidants, ultraviolet absorbers, plasticizers, pigments / dyes, antibacterial agents / antifungal agents, and the like. . In the present invention, it is preferable to use a flame retardant. Examples of the flame retardant include phosphate esters such as triethyl phosphate and tris (β-chloropropyl) phosphate, and phosphate compounds such as phosphite esters such as ethyl phosphite and diethyl phosphite.

  In the production method of the present invention, a multicomponent system having three or more components may be used. However, for the purpose of simplifying the apparatus, the “I liquid” containing the polyisocyanate composition of the present invention as a main component and a polyol ( It is preferable to use a two-component system composed of “R liquid” containing B) as a main component.

  Hereinafter, an example of the preferable specific manufacturing method in the case of setting it as a 2 component type | system | group is shown.

(1) The polyisocyanate composition of the present invention is referred to as “liquid I”, and the polyol (B) is referred to as “liquid R”.

(2) The foaming agent (C), the catalyst (D), the foam stabilizer (E) and the additive (optional component) are mixed in the “I liquid” and / or “R liquid”. The foaming agent (C), catalyst (D) and foam stabilizer (E) are preferably mixed in the “R liquid”.

(3) "I liquid" and "R liquid" are mixed, and the polyisocyanate composition of the present invention and the polyol (B) are mixed with the blowing agent (C), the catalyst (D) and The reaction is carried out in the presence of the foam stabilizer (E), and the reaction system is foamed and cured.

  There is no particular limitation on the mixing device for “I liquid” and “R liquid”. For example, a small mixer, a low pressure or high pressure foaming machine for injection foaming used for producing general urethane foam. A low-pressure or high-pressure foaming machine for slab foaming, a low-pressure or high-pressure foaming machine for continuous lines, a spray foaming machine for spraying work, or the like can be used. In addition, it is preferable to adjust the temperature of “I liquid” and “R liquid” to be mixed within a range of 15 to 30 ° C., respectively.

  In the production method of the present invention, when hydrocarbon (C1) is used as the foaming agent (C), considering the low flash point of the hydrocarbon (C1) and the handling precautions associated therewith, “ In addition to “Liquid I” and “R Liquid”, a three-component system comprising hydrocarbon (C1) as a foaming agent as a separate component (mixed with “I liquid” or “R liquid” immediately before foaming) It is also preferable to use a form to be used.

  The rigid polyurethane foam obtained by the production method of the present invention has a chemical bond such as a urethane bond or a urea bond (so-called urethane foam). Depending on the production conditions, an isocyanurate group can be generated at the time of foaming, and the isocyanurate-modified polyurethane foam (so-called isocyanurate foam) thus obtained is also included in the “rigid polyurethane foam”. The isocyanurate group is generated by trimerizing an isocyanate group with a trimerization catalyst, and can improve mechanical strength, heat resistance, and the like.

  In the production method of the present invention, the preferred isocyanate index [(number of moles of all isocyanate groups in polyisocyanate composition / number of moles of all active hydrogen groups in polyol (B)) × 100] is the case of so-called urethane foam. It is preferably within the range of 50 to 140, more preferably within the range of 70 to 130. In the case of a so-called isocyanurate foam formed using a trimerization catalyst, it is preferably in the range of 140 to 800, more preferably in the range of 150 to 500. When the isocyanate index is less than 50 in the case of urethane foam and less than 140 in the case of isocyanurate foam, the obtained foam may not have sufficient strength and tends to shrink. On the other hand, if it exceeds 140 in the case of urethane foam and exceeds 800 in the case of isocyanurate foam, the brittleness of the resulting foam tends to increase and the adhesiveness tends to decrease.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not construed as being limited by these examples. In the following, unless otherwise specified, “%” and “part” indicate “% by mass” and “part by mass”, respectively.

<Synthesis of organic polyisocyanate composition>
Example 1
According to the formulation shown in Table 1 below, 99.3 kg of “isocyanate A” as polymeric MDI (A1) was charged into a reactor of 100 kg capacity equipped with a stirrer, a cooling pipe, a nitrogen introduction pipe, and a thermometer, and stirred. Warmed to ° C. Subsequently, 0.7 kg of “methyl cellosolve” as ethylene glycol monoether (A2) having a molecular weight of less than 150 was charged into the reactor. After completion of the preparation, the mixture was reacted at 60 ° C. for 2 hours with stirring to obtain a polyisocyanate composition “NCO-1” of the present invention. This polyisocyanate composition “NCO-1” had an isocyanate group content (hereinafter abbreviated as “NCO content” as necessary) of 30.0% and a viscosity (25 ° C.) of 212 mPa · s.

Examples 2-16, Comparative Examples 1-8
In accordance with the formulations shown in Tables 1 to 3 below, “isocyanate A” as polymeric MDI (A1) and “methyl cellosolve”, “ethyl cellosolve” or “ethylene glycol monopropyl ether” as ethylene glycol monoether (A2) having a molecular weight of less than 150 The polyisocyanate compositions “NCO-2” to “NCO-12” of the present invention and the polyisocyanate composition “NCO-13” as a comparative example were used in the same manner as in Example 1 except that each of these was used. ~ "NCO-18" was prepared. Tables 1 to 3 show the isocyanate group content and viscosity (25 ° C.) of the obtained polyisocyanate composition.

<Liquid storage stability of polyisocyanate composition under low temperature atmosphere>
For each of the polyisocyanate compositions “NCO-1” to “NCO-18” obtained in Examples 1 to 12 and Comparative Examples 1 to 6, 200 g was charged in a 200 ml glass sample bottle and sealed with a lid. Then, it was left to stand at −5 ° C. and −10 ° C. for 90 days. The appearance after 90 days elapsed was visually observed and evaluated based on the following criteria. The results are also shown in Tables 1 to 3.

(Evaluation criteria)
“◯”: No crystal precipitation or liquid phase separation is observed.
“X”: Crystal precipitation, liquid phase separation, or turbidity of the liquid, which seems to be a precursor of these, is observed.
The polyisocyanate compositions “NCO-1” to “NCO-18” at the start of measurement are all determined to be “◯”.

  The details of the compounds (components) in Tables 1 to 3 are as follows.

<Isocyanate A (corresponding to (A1) of the present invention)>
(I) MPC peak area ratio by GPC = 40% (polymeric MDI)
(Ii) 4,4′-MDI ratio in MDI = 99% (measured by GC)
(Iii) Isocyanate content = 30.6%
(Iv) Average number of functional groups = 2.3
(V) Acidity = 0.01%
<Methyl cellosolve (corresponding to (A2) of the present invention)>
Ethylene glycol monomethyl ether <Ethyl cellosolve (corresponding to (A2) of the present invention)>
Ethylene glycol monoethyl ether <Ethylene glycol monopropyl ether (corresponding to (A2) of the present invention)>
Ethylene glycol monopropyl ether

<Preparation Examples 1-3>
Polyol compositions “OH-1” to “OH-3” were prepared by uniformly mixing the components according to the formulation shown in Table 4 below.

  Details of the compounds (components) in Table 4 are as follows.

<Polyol (B-1)>
Polyether polyol mainly composed of polyether polyol obtained by addition of propylene oxide with sucrose as an initiator, nominal functional group number = 4.4, nominal hydroxyl value = 390
<Polyol (B-2)>
Polyether polyol mainly composed of polyether polyol obtained by addition of propylene oxide with sorbitol as an initiator, nominal functional group number = 5.0, nominal hydroxyl value = 460
<Polyol (B-2)>
Polyether polyol using toluenediamine as an initiator, nominal hydroxyl value = 460
<Foaming agent (C-1)>
Purified water <foaming agent (C-2)>
Cyclopentane <Catalyst (D-1)>
Amine-based catalyst, trade name “TOYOCAT-TE (manufactured by Tosoh Corporation)”
<Catalyst (D-2)>
Amine-based catalyst, trade name “TOYOCAT-TRC (manufactured by Tosoh Corporation)”
<Catalyst (D-3)>
Amine-based catalyst, trade name “TOYOCAT-DT (manufactured by Tosoh Corporation)”
<Foam stabilizer (E-1)>
Silicone foam stabilizer, trade name "SZ-1725 (manufactured by Dow Corning Toray)"

<Formation (production) of rigid polyurethane foam>
Examples 13 to 26, Comparative Examples 7 to 12

<Part 1 (Measurement of reactivity, etc.)>
“NCO-1” to “NCO-18” are prepared as the polyisocyanate composition (liquid A), and “OH-1” to “OH-3” are prepared as the polyol composition (liquid B). The temperature was adjusted to 20 ° C. In accordance with the combinations shown in Tables 5 to 7 below, a total of 35 g is charged into a paper cup of φ120 mm × 150 mm (height) so that (A liquid) / (B liquid) = 125/100 (volume ratio). A foamable mixture (composition of the present invention / composition for comparison) was obtained by stirring and uniformly mixing for 5 seconds using a laboratory mixer (manufactured by Heidolph, Germany).

  About each of the obtained foamable mixture (composition of the present invention / composition for comparison), the mixture was allowed to stand after stirring and uniform mixing, and the reaction time at the time of foaming (cream time, gel time, tack free time, Rise time) was measured. Moreover, when 10 minutes passed from the start of stirring and mixing, the core portion of the formed rigid polyurethane foam was cut out, and the free expansion density (FRD) was measured. These results are shown in Tables 5-7.

<Part 2 (Measurement of foam physical properties)>
“NCO-1” to “NCO-18” are prepared as the polyisocyanate composition (liquid A), and “OH-1” to “OH-3” are prepared as the polyol composition (liquid B). The temperature was adjusted to 20 ° C. In accordance with the combinations shown in Table 5 to Table 7 below, a total of 100 g is charged into a φ120 mm × 150 mm (height) paper cup so that (A liquid) / (B liquid) = 125/100 (volume ratio). A foamable mixture (composition of the present invention / composition for comparison) was obtained by stirring and uniformly mixing for 5 seconds using a laboratory mixer (manufactured by Heidolph, Germany).

About each of the obtained foamable mixture (composition of the present invention / composition for comparison), 250 mm (width direction) × 250 mm (flow direction of composition = foaming direction) × 50 mm previously adjusted to 45 ° C. A panel made of rigid polyurethane foam was prepared by immediately putting it into a (thickness direction) aluminum mold and opening the upper surface. The panel formed at the time when 10 minutes passed from the start of stirring was taken out of the mold, and the weight obtained by cutting the foam part protruding from the upper surface was defined as the 100% pack weight of the size.

  Next, in accordance with the combinations shown in Tables 5 to 7 below, an amount of a panel made of rigid polyurethane foam of 120% pack in the size at (A liquid) / (B liquid) = 125/100 (volume ratio) In a paper cup each having a diameter of 120 mm × 150 mm (height), and stirred and mixed for 5 seconds using a laboratory mixer (manufactured by Heidolph, Germany). Composition) was obtained.

  About each of the obtained foamable mixture (composition of the present invention / composition for comparison), 250 mm (width direction) × 250 mm (flow direction of composition = foaming direction) × 50 mm previously adjusted to 45 ° C. Immediately, the aluminum mold of (thickness direction) was put in, and when the pouring was finished, the upper surface was closed, and a panel made of rigid polyurethane foam by 120% pack was created. The panel formed when 10 minutes passed from the start of stirring was taken out of the mold and allowed to stand for 24 hours in an atmosphere at 25 ° C. After standing, the closed cell ratio, cell uniformity, thermal conductivity, and dimensional stability (volume change in a low temperature environment and a high temperature and high humidity environment) were measured by the following methods. These results are shown in Tables 5-7.

<Closed cell ratio>
A foam core part having dimensions of 30 mm (width direction) × 30 mm (thickness direction) × 130 mm (composition flow direction = foaming direction) cut from a panel made of rigid polyurethane foam by a 120% pack (test piece) The closed cell ratio (%) was measured in accordance with ASTM D2856.

<Cell uniformity>
The samples for measuring the above-mentioned closed cell ratio and the thermal conductivity and dimensional stability described later were each visually observed to determine the uniform state of the cells.
(Evaluation criteria)
“◯”: A uniform cell is obtained.
“Δ”: When looking closely, there is a portion where the cells are partially non-uniform.
"X": The location where the cells are non-uniform is clear.

<Thermal conductivity>
A panel made of a rigid polyurethane foam with a 120% pack cut from a foam core having dimensions of 200 mm (width direction) × 25 mm (thickness direction) × 200 mm (composition flow direction = foaming direction) (test piece) Was measured using a thermal conductivity measuring device (auto Λ) in accordance with JIS A1412.

<Dimensional stability>
A foam core part having a size of 50 mm (width direction) × 40 mm (thickness direction) × 50 mm (composition flow direction = foaming direction) cut from a panel made of rigid polyurethane foam by a 120% pack (test piece) The dimensional stability was evaluated by measuring the volume change when left for 48 hours in a −30 ° C. (low temperature) atmosphere and in a 70 ° C. and 95% relative humidity (high temperature and high humidity) atmosphere.

Since the rigid polyurethane foam obtained by using the polyisocyanate composition for producing rigid polyurethane foam having closed cells of the present invention has a series of excellent mechanical properties as described above, the board, panel, refrigerator, basket, door , Shutters, sashes, concrete houses, bathtubs, cryogenic tank equipment, refrigerated warehouses, pipe covers, anti-condensation, slabs, etc.

Claims (4)

(A1) Diphenylmethane diisocyanate isomer mixture (a1d) is 20 to 80% by mass, triphenyl or higher diphenylmethane diisocyanate polynuclear condensate (a1p) is 80 to 20% by mass (provided that (a1d) + (a1p) = ( A1) 100% by weight) polymeric MDI, and (A2) an ethylene glycol monoether having a molecular weight of less than 150
A rigid polyurethane having closed cells, which is obtained by mixing and reacting, and having a viscosity at 25 ° C. of 50 to 500 mPa · s and an isocyanate group content of 28.0 to 32.0% by mass Polyisocyanate composition for foam production.   It is obtained by reacting the polyisocyanate composition according to claim 1 and the polyol (B) in the presence of a foaming agent (C), a catalyst (D) and a foam stabilizer (E), A method for producing a rigid polyurethane foam having closed cells.   The method for producing a rigid polyurethane foam having closed cells according to claim 2, wherein hydrocarbon (C1) and water (C2) are used in combination as the foaming agent (C). The method for producing a rigid polyurethane foam having closed cells according to claim 2 or 3, wherein the hydrocarbon (C1) used as the foaming agent (C) is cyclopentane.