JP2009149760A - Production method for rigid polyurethane foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rigid polyuretane foam of an excellent physical property, having a high oxygen index (30 or more), and capable of satisfying a semi-flame-resistance standard. <P>SOLUTION: In this production method for the rigid polyuretane foam, an organic polyisocyanate A and water B are foamed and cured by urea formation reaction and isocyanuration reaction, in the presence of 10-70 wt.% of flame retardant with respect to the whole blended object, a foam stabilizer D and a catalyst E containing an isocyanuration reaction catalyst, and in the presence or absence of 5 mol.% or less of polyol with respect to all the isocynate reactive groups, under the condition where an isocyanate index is 150 or more when calculated using 9 as an isocynate reactive equivalent of water. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a rigid polyurethane foam. More specifically, the present invention relates to a method for producing a rigid polyurethane foam in which a rigid polyurethane foam excellent in flame retardancy having an oxygen index of 30 or more is obtained by using no polyol.

  Rigid urethane foam is particularly suitable for interior and exterior use in buildings because it provides properties such as heat insulation, lightness, strength, fire resistance, and adhesion to face materials. It is provided in the form of a sandwich panel for layer material applications. However, the rigid urethane foam as the core layer material has poor fire resistance against fire, heat, etc., and sufficient fire resistance as a sandwich panel cannot be obtained due to defects such as high smoke generation. For this reason, it has been studied to use phenol foam having excellent fire resistance for the core material, but there is a problem in the corrosion resistance against metal, which is poor in adhesion between the metal plate and phenol foam. Even when a sandwich panel is manufactured by sandwiching phenol foam with a face material such as a metal plate, the strength of the panel is weak. In addition, it has been pointed out that when the density is increased to increase the strength, the lightness is impaired.

  Polyisocyanurate foams obtained by increasing the isocyanate index when reacting and foaming organic polyisocyanates and polyols and using an isocyanurate catalyst as a catalyst are heat insulating materials, lightweight structural materials, and sound absorbing materials. It is widely used as an isocyanurate ring in the polyurethane cross-linking, and exhibits high heat resistance, hydrolysis resistance, and dimensional stability. However, it emits a large amount of smoke during combustion at high temperature heating. Since there are few inspections and there are also few carbonization formation layers, since sufficient fire prevention performance is not obtained, the use is restricted.

As an improvement method, for example, when ammonium polyphosphate, phosphate ester, paranitroaniline sulfonic acid, aluminum hydroxide, magnesium hydroxide, etc. are added and contacted with a flame, these additives promote carbonization of the foam. There is a method for reducing the amount of smoke generated (Patent Document 1, etc.). Further, as a method for reducing smoke generation by adding refractory inorganic powder to suppress flammability, for example, calcium carbonate, ammonium sulfate or the like is added, and an inert gas (CO ₂ , NH _3, etc.) generated by thermal decomposition is added. ), A method of diluting the combustible gas generated from the foam, suppressing combustion, and reducing combustibility has been attempted (Patent Document 2 and the like).

JP 2002-338651 A JP 7-217054 A

  However, even with such a method, the oxygen index is still about 22 to 25 and the flame retardancy is insufficient.

  An object of the present invention is to provide a rigid polyurethane foam having good physical properties, a high oxygen index (30 or more), and capable of achieving a quasi-incombustible standard.

  In other words, the present invention comprises organic polyisocyanate (A) and water (B) in an amount of 10 to 70% by mass of flame retardant (C), foam stabilizer (D), and isocyanuration reaction catalyst based on the total formulation. In the presence of the catalyst (E) containing and in the presence or absence of a polyol of 5 mol% or less of the total isocyanate-reactive groups, the isocyanate index (total isocyanate) This is a method for producing a rigid polyurethane foam, which is foamed and cured by a urea-forming reaction and an isocyanurate-forming reaction under a condition that the molar ratio of groups / total isocyanate-reactive groups is 100 times or more.

  Moreover, this invention is a manufacturing method of the said rigid polyurethane foam characterized by organic polyisocyanate (A) being polymeric MDI.

  According to the present invention, it is possible to provide a rigid polyurethane foam having a high oxygen index (30 or more) and capable of achieving a quasi-incombustible standard.

  The method for producing a rigid polyurethane foam of the present invention comprises organic polyisocyanate (A) and water (B), 10 to 70% by mass of flame retardant (C), foam stabilizer (D), When the isocyanate reactive equivalent of water is calculated as 9 in the presence of the catalyst (E) containing the isocyanuration reaction catalyst and in the presence or absence of a polyol of 5 mol% or less of all isocyanate-reactive groups. Is characterized by being foamed and cured by a urea-forming reaction and an isocyanurate-forming reaction under a condition where the isocyanate index (100 times the molar ratio of all isocyanate groups / all isocyanate-reactive groups) is 150 or more. When a polyol is used, the production of isocyanurate groups imparting flame retardancy is reduced, and thus flame retardancy tends to be insufficient.

  From the viewpoint of imparting flame retardancy in the resulting rigid polyurethane foam, the organic polyisocyanate (A) used in the present invention is most preferably polymeric MDI having one benzene ring per isocyanate group.

  This polymeric MDI is a mixture of organic isocyanate compounds with different degrees of condensation obtained by converting and isomerizing an amino group to an isocyanate group by phosgenation or the like of a condensation mixture (polyamine) obtained by the condensation reaction of aniline and formalin. The composition of the finally obtained polymeric MDI can be changed by changing the raw material composition ratio and reaction conditions during the condensation. The polymeric MDI used in the present invention has different numbers of reaction liquids after conversion to isocyanate groups, or removal of the solvent from the reaction liquids, or bottoms obtained by distilling and separating part of the MDI, reaction conditions and separation conditions, etc. It may be a mixture of seeds. Further, a part of the isocyanate group may be modified to biuret, allophanate, carbodiimide, oxazolidone, amide, imide or the like.

  The average number of functional groups of polymeric MDI is 2.3 or more, and preferably the number of functional groups is 2.3 to 3.1. The isocyanate content is 28 to 33% by mass, preferably 28.5 to 32.5% by mass.

  Polymeric MDI contains diphenylmethane diisocyanate (MDI) having two benzene rings and two isocyanate groups in one molecule, a so-called dinuclear component. The isomers constituting MDI are 2,2'-diphenylmethane diisocyanate (hereinafter abbreviated as 2,2'-MDI), 2,4'-diphenylmethane diisocyanate (hereinafter abbreviated as 2,4'-MDI), There are three types of 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as 4,4'-MDI). The isomer composition ratio of MDI is not particularly limited, but the 4,4′-MDI content is preferably 70% by mass or more, preferably 90 to 99.9% by mass because the strength of the resulting foam is improved. . The MDI content of polymeric MDI and the isomer composition ratio of MDI can be determined from a calibration curve based on the area percentage of each peak obtained by GPC or gas chromatography (hereinafter abbreviated as GC).

  The polymeric MDI used in the present invention has a peak area ratio of 20 to 70% of a dinuclear (having two benzene rings in one molecule) component in gel permeation chromatography (hereinafter abbreviated as GPC). And preferably 25-65%. When the peak area ratio of the binuclear body exceeds 70%, the strength of the rigid polyurethane foam obtained is lowered and the brittle body tends to become brittle. On the other hand, when it is less than 20%, the viscosity of the resulting polyisocyanate increases, and the filling property into the mold tends to decrease.

  In the present invention, if necessary, a polyisocyanate other than the above-mentioned polymeric MDI can be used. Examples include MDI isocyanurate-modified products, uretonimine-modified products, allophanate-modified products, and the like. In addition, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylene-1,4-diisocyanate, xylene-1,3-diisocyanate, tetramethylxylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, etc. Aromatic diisocyanates, tetramethylene diisocyanates, hexamethylene diisocyanates, 3-methyl-1,5-pentane diisocyanates, lysine diisocyanates and other aliphatic diisocyanates, isophorone diisocyanates, hydrogenated tolylene diisocyanates, hydrogenated xylene diisocyanates, hydrogenated diphenylmethane diisocyanates, etc. And alicyclic diisocyanates. In addition, these polymeric materials, urethanized products, ureaated products, allophanated products, biuretized products, carbodiimidized products, uretoniminate products, uretdioneized products, isocyanurated products, and the like, and a mixture of two or more of these may be mentioned. However, when an active hydrogen group-containing compound is used as a modifying agent, the oxygen index is lowered, and therefore, a type that is not modified with an active hydrogen group-containing compound is preferable.

  Water (B) used in the present invention serves as a foaming agent and an isocyanate group-reactive substance. That is, when water and an isocyanate group react, an amino group and carbon dioxide gas are generated. This carbon dioxide gas causes the reaction system to foam. The amino group is polymerized by reacting with an isocyanate group present in the reaction system to form a urea group.

  The isocyanate index (isocyanate group / active hydrogen × 100) during the reaction is preferably 300 to 600, and most preferably 350 to 500. If the isocyanate index is too low, the amount of isocyanurate groups present in the resulting rigid polyurethane foam is reduced, resulting in insufficient flame retardancy. If it is too high, the resulting rigid polyurethane foam tends to be brittle.

  The present invention does not intentionally add a polyol as an isocyanate-reactive compound, but does not prevent mixing from a catalyst solvent or a foam stabilizer having an isocyanate-reactive group. The number of moles of isocyanate-reactive groups entering should not exceed 5% of the number of moles of total isocyanate-reactive groups.

  In the present invention, the flame retardant (C) is essential. This is because only the isocyanurate group has insufficient flame retardancy. Examples of the flame retardant (C) used in the present invention include triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, diethylphenyl phosphate , Dimethylphenyl phosphate, resorcinol diphenyl phosphate, tris (chloropropyl) phosphate, tris (dichloropropyl) phosphate, tris (tribromoneopentyl) phosphate, etc., ethyl phosphite, diethyl phosphite, etc. Phosphate compounds of phosphites, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and other metal hydroxides, melamine resins, Chromatography, antimony trioxide, zinc oxide, calcium carbonate, and the like.

  In view of ease of mixing, the flame retardant (C) is preferably a phosphoric ester-based room temperature liquid. The amount of (C) used is 10 to 70% by mass, preferably 15 to 50% by mass, based on the total formulation.

  Examples of the foam stabilizer (D) used in the present invention include known silicone surfactants, such as L-5340, L-5420, L-5421, L-5740, L-made by Toray Dow Corning. 580, SZ-1142, SZ-1642, SZ-1605, SZ-1649, SZ-1675, SH-190, SH-192, SH-193, SF-2945F, SF-2940F, SF-2936F, SF-2937F, SRX-294A, Shin-Etsu Chemical F-305, F-341, F-343, F-374, F-345, F-348, Goldschmitt B-8404, B-8407, B-8465, B -8444, B-8467, B-8462, B-8433, B-8466, B-8870, B-8450 and the like. The amount of (D) used is suitably 0.1 to 5% by mass relative to the organic polyisocyanate (A).

  It is essential that the catalyst (E) used in the present invention contains an isocyanuration reaction catalyst. Examples of the isocyanuration reaction catalyst include 2,4,6-tris (dimethylaminomethyl) phenol, triazines such as 1,3,5-tris (dimethylaminopropyl) hexahydro-s-triazine, 2,4-bis ( Amine compounds such as dimethylaminomethyl) phenol, potassium 2-ethylhexanoate, sodium 2-ethylhexanoate, potassium acetate, sodium acetate, 2-ethylaziridine and the like, tertiary amine carboxylates, etc. Examples include quaternary ammonium compounds, diazabicycloundecene, lead compounds such as lead naphthenate and lead octylate, alcoholate compounds such as sodium methoxide, phenolate compounds such as potassium phenoxide, and the like.

  In addition, other catalysts can be used in combination. 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. These catalysts can be used alone or in combination of two or more.

  The amount of the catalyst (E) used is suitably 0.01 to 15% by mass relative to the organic polyisocyanate (A).

  Furthermore, for example, carbonate compounds such as ethylene carbonate and propylene carbonate can be used as a cocatalyst for promoting the reaction.

  In the present invention, other additives can be used. Examples of the additive include plasticizers, fillers, colorants, organic or inorganic fillers, antioxidants, ultraviolet absorbers, plasticizers, pigments / dyes, antibacterial agents / antifungal agents, and the like.

  Specific steps in the method for producing a rigid polyurethane foam of the present invention include adding an organic polyisocyanate, water, a flame retardant, a foam stabilizer, and a catalyst, and an isocyanate index in the range of 300 to 600, preferably 350 to 500. Stir and mix at 10 to 40 ° C. and 2000 to 8000 rpm for 3 to 10 seconds and immediately flow into a mold, or foam using a low pressure or high pressure foaming machine generally used in urethane foam manufacturing equipment You can also. In this case, if the mold or the free-foaming container is heated to 40 ° C. or higher, the foaming time can be shortened.

The rigid polyurethane foam thus obtained, particularly the molded rigid polyurethane foam having a layer thickness of 30 to 50 mm, has a foam core density of 15 to 45 kg / m ³ in the method prescribed in JIS A9526. Is preferred. When the core density (heart density) is less than 15 kg / m ³ , the strength is remarkably lowered and shrinks, and when it exceeds 45 kg / m ³ , the combustion amount of the rigid polyurethane foam increases to increase the density and flame retardancy. Is significantly reduced. Accordingly, the core density is 15 to 45 kg / m ^3, preferably 20 to 40 kg / m ³ .

  The rigid polyurethane foam obtained in this way is particularly excellent in flame retardancy, and can also be produced that satisfies the quasi-incombustible standard. The rigid polyurethane foam obtained by the present invention can be applied to fields such as building materials, household goods, leisure goods, such as refrigerators, freezers, cooler boxes, vending machines, showcases and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to these. In Examples and Comparative Examples, “%” indicates “mass%”.

[Production and evaluation of rigid polyurethane foam]
Examples 1-5, Comparative Examples 1-2
A rigid polyurethane foam was produced using the raw materials shown in Table 1.
The foamable mixture obtained by stirring and mixing with a lab mixer is injected from above into a top-open mold having internal dimensions of width = 500 mm, thickness = 60 mm, depth = 500 mm, and foaming / curing I let you. The mold was removed after 10 minutes from the start of casting to obtain a molded product having dimensions of 500 mm (width direction) × 60 mm (thickness direction) × 500 mm (composition flow direction = foaming direction).

In Table 1, MR-200: Millionate (registered trademark) MR-200
Polymeric MDI
Made by Nippon Polyurethane Industry Co., Ltd.
Isocyanate content = 31.0%
Dinuclear content = 41%
4,4′-MDI content in the binuclear body = 99%
TCPP: Tris (β-chloropropyl) phosphate CR530: Halogen-containing condensed phosphate ester CR733S: Non-halogen condensed phosphate ester * All flame retardants are B-8462 manufactured by Daihachi Chemical Industry Co., Ltd .: Silicon foam stabilizer
Gold Schmitt P15: Product name DABCO (registered trademark) P15
Tertiary amine catalyst
Air products TR20: Trade name TOYOCAT (registered trademark) -TR20
Tertiary amine catalyst
DT manufactured by Tosoh Corporation: TOYOCAT-DT
Pentamethyldiethylenetriamine
Tertiary amine catalyst
Tosoh Co., Ltd. NMM: N-methylmorpholine polyol-1: diethylene glycol / phthalic polyester polyol
Hydroxyl value = 210 mgKOH / g
Polyol-2: Poly (oxypropylene) polyol
Initiator = mixture of sucrose and glycerin
Hydroxyl value = 375 mgKOH / g

〔Evaluation methods〕
Foamed state:
Evaluation by visual observation ○: Abnormality is not confirmed in appearance ×: Oxygen index in which depression or shrinkage is confirmed:
Corn calorie test according to JIS K7201:
Conforms to ISO 5660 Cone calorimeter ("CONE2A" manufactured by Atlas)
Dimensional stability:
A sample [100 mm (width direction) × 60 mm (thickness direction) × 100 mm (foaming direction)] is left in an atmosphere of temperature 25 ° C. × humidity 50 RH% for 48 hours, and dimensions before and after being left (foaming direction, width direction, thickness) The change rate was measured from (direction).
○: Change rate of less than 1% ○ to Δ: Change rate of 1% to less than 2% Δ: Change rate of 2% to less than 5% Δ ×: Change rate of 5% to less than 10% ×: Compression of 10% or more Strength:
For the sample [100 mm (width direction) × 60 mm (thickness direction) × 100 mm (foaming direction)], the compressive stress at 10% compression in the thickness direction was measured in accordance with JIS K 7220.
○: Abnormality is not confirmed in appearance ×: Depression or contraction is confirmed

From Table 1, the rigid polyurethane foam according to the present invention showed excellent flame retardancy, and had good appearance and compressive strength. In particular, the oxygen index was as high as 30 or more. On the other hand, the comparative example by the conventional prescription was poor in moldability because the comparative example 2 was confirmed to be depressed, and in the comparative examples 1 and 3, the total heat generation was particularly large.

Claims (2)

Catalyst (E) containing 10 to 70% by mass of flame retardant (C), foam stabilizer (D), and isocyanuration reaction catalyst with respect to the total formulation of organic polyisocyanate (A) and water (B) And in the presence or absence of 5 mol% or less of the total isocyanate-reactive group polyol,
Foaming by urea reaction and isocyanurate reaction under conditions where the isocyanate index (100 times the molar ratio of total isocyanate groups / total isocyanate reactive groups) when calculated with an isocyanate reactive equivalent of 9 is 150 or more A method for producing a rigid polyurethane foam characterized by curing. 2. The method for producing a rigid polyurethane foam according to claim 1, wherein the organic polyisocyanate (A) is polymeric MDI.