JP4587115B2 - Rigid polyurethane foam molding composition and method for producing rigid polyurethane foam using the composition - Google Patents

Description

  The present invention relates to a rigid polyurethane foam molding composition having a closed cell ratio of 0 to 75% and a production method thereof. More specifically, when water is used as a foaming agent, the scorch inside the foam is easily improved and desired. Composition for molding rigid polyurethane foam having a closed cell ratio of 0 to 75% (hereinafter abbreviated as “open cell”), which can easily realize low density foam while ensuring mechanical properties It is about the method.

  Conventionally, as a method for producing a rigid polyurethane foam, a method using chlorofluorocarbons (CFCs such as CFC-11, HCFC-141b, HCFC-123, HCFC-22, and CFC-12, and HCFCs) containing chlorine as a foaming agent. Is known. However, CFCs and HCFCs are considered to be one of the causes of the environmental problem of ozone layer destruction, and reduction and elimination are about to be implemented.

  In recent years, hydrofluorocarbons (hereinafter abbreviated as “HFCs”) have attracted attention as blowing agents that replace these CFCs and HCFCs. However, although HFCs do not have an ozone depletion potential (ODP), they have an environmental problem of high global warming potential (GWP).

  Therefore, water foaming that uses carbon dioxide gas generated by the reaction of water and isocyanate groups as a foaming agent has attracted attention.

  When using only water as a foaming agent, and using a polyol polyol as a polyol, such as propylene glycol, trimethylolpropane, glycerin, ethylenediamine, tolylenediamine, pentaerythritol, methyl glucoside, sorbitol, sucrose, or the like, or When using only polyester as a foaming agent and using polyester polyol obtained by condensation of polyhydric alcohol and polycarboxylic acid, carbon dioxide gas generated and trapped in bubbles permeates the resin compared to fluorocarbons. Cheap. Therefore, the air pressure in the bubbles is lowered, and there is a problem that the dimensional stability is generally deteriorated as compared with foams using CFCs, HCFCs, or HFCs as foaming agents.

  For this reason, in applications where low thermal conductivity, that is, high heat insulation is not required, a polyol containing a substance that makes bubbles continuous (hereinafter abbreviated as “open cell forming agent”) is used, or an open cell forming agent is used separately. By adding or selecting a foam stabilizer that easily causes open-cell formation, the rigid polyurethane foam generally obtained with a closed cell ratio of 85% or more is made continuous, that is, open-celled, Attempts have been made to match the atmospheric pressure in the bubbles with the atmospheric pressure, thereby improving dimensional stability.

  In general, open cell formation is achieved by breaking a part of a cell wall at a stage where foaming has progressed to some extent in the process of forming a foam. Open cell formation occurs when the inside of the foam is in a high temperature state due to heat of reaction, so if oxygen is supplied to the inside of the foam by open cell formation, the resin will burn and the inside of the foam will be burnt or ignited. There are things to do. This is called a scorch. When scorching occurs, the physical properties of the foam are greatly deteriorated due to the burning of the foam, and there is a risk of fire if the combustion becomes intense.

  Until now, as a method of improving the generation of scorch, a method of adding a specific additive such as an antioxidant, for example, a reaction product of a diarylamine and a lower alkyl ketone, a diarylarylenediamine, a new specific A method of adding a scorch-preventing composition comprising a hindered phenol as the third component (see, for example, Patent Document 1), a stabilizer composition comprising a diarylamine, a sterically hindered phenol, and pentaerytriol diphosphite Has been proposed (for example, see Patent Document 2).

  Further, as a method for improving the generation of scorch, a method using a polyol having a specific structure, for example, a method using a composition comprising a specific hydroxy compound as a polyol (see, for example, Patent Document 3), a specific polyol and a specific A method of using a monool in combination (for example, see Patent Document 4) has been proposed.

  Further, as a method for improving the generation of scorch, a method using a pre-modified organic polyisocyanate, for example, a method using a polymethylene polyphenyl isocyanate prepolymer obtained by reacting a hydroxyl group-containing compound and polymethylene polyphenyl isocyanate in advance (for example, Patent Document 5) has been proposed.

  In addition, as a method for improving the generation of scorch, a method of adding liquid carbon dioxide and foaming in order to suppress heat generation has been proposed (for example, see Patent Document 6).

  However, the foam physical properties deteriorate due to the large amount of additives, the cost increases in economic terms, the work costs and economic costs increase due to the change in polyol composition and organic isocyanate, and the economic costs associated with the use of special liquids. This leads to various problems such as an increase in cost, and is inconvenient in terms of workability and economy.

Meanwhile in recent years, in the industry using interconnected cells polyurethane foams, from workability point of view such as, low density relative to interconnected cells polyurethane foam was placed lighter in mind, inter alia, foam density 30kg / m ³ less dense The demand is increasing. However, as described above, in the process of forming the foam, in view of the mechanism of achieving open cell formation by destroying a part of the cell wall at a stage where foaming has progressed to some extent, low density is achieved. It is very difficult.

  In order to solve this reduction in density, for example, a method of introducing a large amount of water as a foaming agent into the composition is conceivable. However, this method has a problem that the above-described scorch is more likely to occur.

JP-A-2-49059 (pages 2 to 3) JP-T-8-503992 (pages 7-11) JP-A-7-10952 (pages 4-8) JP-A-8-193118 (pages 4-7) JP-A-7-53655 (pages 3-4) JP-T-2001-526728 (9th page)

  The object of the present invention is to provide an open-celled rigid polyurethane foam that, when using water as a foaming agent, improves the scorch by an easy and inexpensive method, resulting in improved physical properties and safe production, in view of the above-mentioned problems. It is providing the composition for manufacturing, and its manufacturing method.

  It is another object of the present invention to produce an open-celled rigid polyurethane foam that can easily realize a low-density foam while ensuring desired mechanical properties without introducing a large amount of water as a blowing agent. It is providing the composition for manufacturing, and its manufacturing method.

In order to solve the above-mentioned problems, the present inventors have made extensive studies, and as a result, organic polyisocyanates that are raw materials for producing open-celled rigid polyurethane foams, polyols including those having a specific structure, and foaming agents As a modifying additive, a maleic acid ester having a molecular weight of less than 500 is introduced into a raw material containing water, a catalyst, and a foam stabilizer as a specific additive with respect to 100 parts by mass of polyol or organic polyisocyanate, and The inventors have found that it is very effective to use a composition having an isocyanate index, and have reached the present invention.

That is, the present invention is as the following (1) to (2) .
(1) (A) Organic polyisocyanate, (B) polyol, (C) catalyst, (D) modifying additive, (E) foam stabilizer, (F) for rigid polyurethane foam molding comprising water as foaming agent In the composition, 5 to 30 parts by mass of polypropylene glycol (b-1) having a molecular weight of 2000 to 5000 is used as (B) polyol with respect to 100 parts by mass of (B) polyol, and (D) a molecular weight of 500 is used as a modifying additive. The maleic ester of less than (B) is used in an amount of 0.01 to 20 parts by mass with respect to 100 parts by mass of the polyol, and the isocyanate index in the composition is less than 100. % Rigid polyurethane foam molding composition.

(2) A method for producing a rigid polyurethane foam having a closed cell ratio of 0 to 75%, wherein the molding composition according to (1) is used.

As in the composition of the present invention, 5 to 30 parts by mass of polypropylene glycol (b-1) having a molecular weight of 2000 to 5000 is used as a polyol with respect to 100 parts by mass of the (B) polyol , and the molecular weight is less than 500 as a modifying additive. By using 0.01 to 20 parts by mass of maleic acid ester of 100 parts by mass of polyol or organic polyisocyanate and making the isocyanate index in the composition less than 100, an easy and inexpensive method is used. Scorch generation in open-celled rigid polyurethane foam using water as a foaming agent is suppressed without significantly changing the resin composition, and the density of the resulting open-celled polyurethane foam is greatly improved, and excellent It became possible to maintain the physical properties of the foam.

  The present invention will be described in further detail.

  In general, rigid polyurethane foam has the largest use as a heat insulating material, and in this field, the heat insulating performance is the most important factor. In order to improve this heat insulation performance, it is necessary to make each bubble as independent as possible and stop the movement of gas between the bubbles.

  The rigid polyurethane foam in the present invention is used for applications in which this heat insulation performance is not given priority as a factor, that is, applications in which individual bubbles may be as continuous as possible. By making each bubble as continuous as possible, specifically by setting the closed cell ratio to 0 to 75%, the gas in the bubble is quickly replaced with air. Therefore, although the heat insulation performance is inferior to the rigid polyurethane foam having closed cells, since the atmospheric pressure inside the foam matches the atmospheric pressure, the mechanical properties of the foam, particularly the dimensional stability, are remarkably improved.

  As (A) organic polyisocyanate in the present invention, various known polyfunctional aliphatic, alicyclic and aromatic isocyanates can be used. For example, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 4, 4-dicyclohexylmethane diisocyanate (H12MDI), tolylene diisocyanate (TDI), crude tolylene diisocyanate, modified tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate (4,4'-MDI), polymeric MDI (crude diphenylmethane diisocyanate, crude MDI and the like: hereinafter abbreviated as “p-MDI”), modified diphenylmethane diisocyanate (carbodiimide modification, prepolymer modification, etc.), orthotoluidine diisocyanate (TODI), naphthylene diisocyanate (NDI), xylylene diisocyanate (XDI), and the like lysine diisocyanate (LDI). In the present invention, 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 2,2'-diphenylmethane diisocyanate (2,2'-MDI), 4, 4'-MDI, and three benzene rings are used. It is preferable to use p-MDI which is a mixture of polymethylene polyphenylene polyisocyanate having the above or a mixture of the p-MDI and other isocyanate components. Among them, from the viewpoint of mechanical properties and cost of the obtained rigid polyurethane foam. From the viewpoint of being excellent in the above, the total ratio of 2,4′-MDI and 2,2′-MDI in diphenylmethane diisocyanate having two benzene rings is 0 to 30% by mass, and the diphenylmethane diisocyanate is 25-70% by mass, polymethylene poly having 3 or more benzene rings Polyphenylene polyisocyanate is particularly preferred to use p-MDI consisting of 30 to 75 wt%.

  In the present invention, (B) polyol that can react with an isocyanate group, that is, an active hydrogen compound having two or more active hydrogen-containing functional groups, has a molecular weight of 2000 to 5000 (preferably 3000 to 5000, more preferably 4000 to 5000). 5000) polypropylene glycol (a compound obtained by extending the chain using propylene glycol with propylene glycol as a starting material and having 2 hydroxyl groups at the terminal) (b-1) (5) per 100 parts by weight of polyol (B) To 30 parts by mass (preferably 10 to 25 parts by mass, more preferably 10 to 20 parts by mass). When the (b-1) is less than 5 parts by mass, the desired closed cell ratio of the present invention cannot be obtained. Moreover, when this (b-1) exceeds 30 mass parts, the dimensional change of the rigid polyurethane foam obtained will become large.

  In the present invention, (B) the polyol used in addition to the above (b-1) includes a compound having two or more active hydrogen-containing functional groups such as a hydroxyl group and an amino group, or two or more kinds of the compounds. Any known mixture can be used as long as it is a mixture. In the present invention, in particular, from the viewpoint of improving the mechanical properties of the resulting rigid polyurethane foam, (B) a compound having two or more hydroxyl groups or a mixture thereof as a polyol other than the above (b-1), or It is preferable to use a mixture containing it as a main component and further containing polyamine or the like.

  However, when a compound having a primary amino group that reacts with the modifying additive (D), which will be described in detail later, is used as the polyol (B), (D) the modifying additive is previously combined with (A) an organic polyisocyanate. In order to obtain the intended effect of the present invention, such as mixing and using the three components of the polyol component, organic polyisocyanate component, and (D) modifying additive at the same time during foam molding, foaming is also performed. By the time of molding, it is necessary to prevent the compound having a primary amino group and (D) the modifying additive from touching.

  Examples of the compound having two or more hydroxyl groups include polyether polyols (excluding the glycol (b-1)), polyester polyols, polyhydric alcohols, and hydroxyl group-containing diethylene polymers. In addition, it is also possible to use a polyol composition in which fine particles of vinyl polymer are dispersed in a polyether-based polyol, mainly called a polymer polyol or a graft polyol.

  Examples of the polyester polyol include polyhydric alcohols, polyhydric carboxylic acid condensation polyols, and cyclic ester ring-opening polymerization polyols. Polyhydric alcohols include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and glycerin. , Trimethylolpropane, pentaerythritol, diethanolamine, triethanolamine and the like. Examples of the polyvalent carboxylic acid include phthalic anhydride, terephthalic acid, dimethyl terephthalic acid, adipic acid, and het acid.

  In the present invention, from the viewpoint of being excellent in workability, economic efficiency, etc., the polyol of (b-1) and two types of polyether polyols, or the two types as main components, It is preferably used in combination with polyester polyols, polyhydric alcohols, polyamines, alkanolamines and other active hydrogen compounds.

  In the present invention, polyether polyols (excluding the glycol of (b-1) above) are used as polyhydric alcohols, sugars, alkylamines, alkanolamines, other initiators, cyclic ethers, particularly propylene oxide, It is preferable to use a polyether polyol obtained by adding an alkylene oxide such as ethylene oxide.

  In addition, the hydroxyl value which (B) polyol has is selected from the range of 15-2000 (mgKOH / g) according to the use of the rigid polyurethane foam obtained, ie, various physical properties requested | required.

  (B) Examples of commercially available polyols include polyether polyols obtained by adding propylene oxide to sucrose (for example, “GR-35 (hydroxyl value 400 (mgKOH / g): Takeda Pharmaceutical ( ))), Polyether polyol obtained by adding propylene oxide to toluenediamine (for example, “NT-400 (hydroxyl value 400 (mgKOH / g): manufactured by Mitsui Chemicals)”), glycerin Polyether polyol with added propylene oxide and ethylene oxide (for example, "FA-103T (Hydroxyl value 50 (mgKOH / g): Sanyo Chemical Industries, Ltd.)"), propylene oxide added to sucrose and triethylenediamine "EX-425R (Hydroxyl value 42) manufactured by Asahi Glass Co., Ltd. (MgKOH / g)) "and the like as examples.

In the present invention, (D) maleic ester having a molecular weight of less than 500 used as a modifying additive is added in an amount of 0.01 to 20 parts by mass with respect to 100 parts by mass of (B) polyol or (A) organic polyisocyanate. In particular, it is more preferable to add 0.1 to 10 parts by mass. If it is less than 0.01 part by mass, the effect of improving the scorch is small, which is not preferable. On the other hand, if it exceeds 20 parts by mass, the dimensional stability deteriorates due to the influence of the modifying additive remaining inside the foam, which is not preferable.

(D) As a modifying additive, dimethyl maleate, diethyl maleate, maleic acid having a molecular weight of less than 500 from the viewpoint of good mixing with polyol and preferably low viscosity. Maleic acid esters such as dibutyl and dioctyl maleate (di-2-ethylhexyl maleate) are used. Among them, from the viewpoint that it is most excellent in terms of viscosity, miscibility with organic isocyanate or polyol, odor, safety, price, etc., and from the viewpoint that it is easy to achieve the reduction in density that is the object of the present invention. It is particularly preferable to select and use dioctyl maleate.

  (D) The modifying additive reacts rapidly with primary amino groups, but does not react with hydroxyl groups in (B) polyols or isocyanate groups in (A) organic polyisocyanates. Therefore, as a form to obtain an open-celled rigid polyurethane foam, (B) a mixture before molding (polyol premix) containing polyol and (A) a mixture before molding containing organic polyisocyanate (or (A) organic polyisocyanate alone) )) In the form obtained by mixing at the time of molding, (D) a pre-molding mixture containing (B) a polyol, or (A) a pre-molding mixture containing an organic polyisocyanate (D). Alternatively, it is used by a method in which it is added in advance to either one or both of (A) organic polyisocyanate alone). (D) The mixture before molding to which the modifying additive is added has an excellent effect of reducing the viscosity of the liquid and improving the mixing property of the liquid.

  Moreover, as a form which obtains open-cell rigid polyurethane foam, (B) Mixture before molding containing polyol (polyol premix) and (A) Mixture before molding containing organic polyisocyanate (or (A) Organic polyisocyanate alone In addition to (D), it is of course possible to obtain (D) a third component without previously adding a modifying additive or the like and mixing it at the time of molding in a state of three or more liquids.

  In the present invention, when (B) a polyol and (A) an organic polyisocyanate are reacted, the use of (C) a catalyst is required for the purpose of accelerating the reaction. (C) Catalysts include (B) metal compound catalysts such as organotin compounds that promote the reaction of active hydrogen-containing groups in polyols and (A) isocyanate groups in organic polyisocyanates, triethylenediamine (TEDA), tetra A tertiary amine catalyst such as methylhexamethylenediamine (TMHMDA), pentamethyldiethylenetriamine (PMDETA), dimethylcyclohexylamine (DMCHA), bisdimethylaminoethyl ether (BDMAEA) is used. A trimerization catalyst for reacting the isocyanate groups with each other is also used depending on the purpose.

  In the present invention, the use of (E) a foam stabilizer is required for the purpose of forming good bubbles. (E) Any foam stabilizer can be used as long as it is a known foam stabilizer in the polyurethane industry. Examples thereof include silicone foam stabilizers and fluorine-containing compound foam stabilizers. In particular, for rigid polyurethane foams that inherently have a closed cell ratio of more than 75%, in order to reduce the closed cell ratio to 75% or less, an adjustment that shows a tendency to promote the formation of open cells is necessary. A foaming agent may be selected and used. Examples of foam stabilizers exhibiting such a tendency include “SZ-1923 (manufactured by Nippon Unicar Co., Ltd.)”, “SZ-1932 (manufactured by Nippon Unicar Co., Ltd.)”, and “F-370 (Shin-Etsu Chemical Co., Ltd.). ) Made) ".

  In the present invention, for example, a filler, a stabilizer, a colorant, a flame retardant, and the like can be used as an auxiliary agent as necessary. A typical flame retardant is tris (chloropropyl) phosphate (TCPP). In particular, in the present invention, in order to make the closed cell ratio 75% or less for the rigid polyurethane foam originally having a closed cell ratio exceeding 75%, in the present invention, the continuous cell generation is promoted as necessary. Such auxiliary agents, for example, alkaline earth metal salts or zinc salts of saturated higher fatty acids such as calcium stearate, magnesium stearate, strontium stearate, zinc stearate, calcium myristylate and the like can also be used.

  The rigid polyurethane foam molding composition according to the present invention has an isocyanate index in order to easily improve the scorch inside the foam and to easily reduce the density of the foam while ensuring the desired mechanical properties. It is characterized in that it is used as less than 100 (preferred range is 70 or more and less than 100, more preferred range is 80 or more and less than 98, and particularly preferred range is 85 or more and less than 96). When the isocyanate index is 100 or more, it is not preferable because of the occurrence of scorch inside the foam due to the presence of excess isocyanate groups, particularly deterioration of mechanical properties such as dimensional stability, and difficulty in reducing the density of the foam. The isocyanate index is an equivalent ratio of (A) an isocyanate group in an organic polyisocyanate and (B) a polyol and (F) an active hydrogen-containing group in water as a blowing agent, that is, all isocyanate groups. / The value obtained by multiplying the equivalent ratio of all active hydrogen-containing groups by 100.

  In the present invention, an open cell polyurethane foam can be obtained by using these raw materials. The present invention is useful in the production of open cell rigid polyurethane foam.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is limited to only the Example shown below and is not interpreted.

Measurement of foaming speed The raw materials shown in Table 1 and Table 2 were prepared, and preparations such as preparing a polyol premix and an isocyanate component based on the blending ratios shown in Table 1 and Table 2 were made. Each of these was adjusted to 20 ° C., and weighed into a 2000 ml death cup so that the total weight was 500 g, and stirred for 5 seconds with a homomixer (rotation speed: 7000 rpm) to obtain a rigid polyurethane foam molding composition. After the stirring, the composition was immediately poured into an open top aluminum mold having an inner size of 250 × 250 × 250 mm that had been temperature-controlled in advance at 40 ° C., and the reaction rate (cream time, gel time, rise time, The tack free time was measured, and then the free rise density was measured and the presence or absence of scorch was confirmed by the following method.

Free rise density Measured according to JIS A9511 (unit in Table: kg / m ³ ).

The presence or absence of scorch For the free-foam foam for which the reaction rate was measured, after the reaction rate was measured, the foam was allowed to stand for 10 minutes without demolding. confirmed. The case where there was no trace of scorch was evaluated as “◯”, and the case where the trace of scorch was observed was evaluated as “x”.

Preparation of Panel Foam Foam The raw materials listed in Tables 1 and 3 were prepared, and preparations such as preparing a polyol premix and an isocyanate component based on the blending ratios described in Tables 1 and 3 were made. Each of these was adjusted to 20 ° C., and weighed into a 2000 ml death cup so that the total weight was 650 g, and stirred for 5 seconds with a homomixer (rotation speed: 7000 rpm) to obtain a rigid polyurethane foam molding composition. After the completion of stirring, the mixture was immediately poured into an aluminum mold having an inner dimension of 500 × 500 × 60 (thickness) mm, which had been temperature-controlled at 40 ° C., and demolded 10 minutes later to obtain a panel foam. After demolding, the mixture was allowed to stand at room temperature for 24 hours, and then the following items were measured.
Panel foaming density: JIS A9511 (unit in Table: kg / m ³ )
High temperature dimensional change rate: The following measurement method (unit: volume% in Table 1)
Low-temperature dimensional change rate: The following measurement method (unit: volume% in Table 1)
Closed cell ratio: ASTM D2856 compliant

Dimensional change rate The panel foamed foam was cut into a size of 50 × 50 × 50 mm. About this cut foam sample, the dimensional change (volume change) rate 48 hours after was measured on -20 degreeC or 70 degreeC constant atmosphere conditions.

Closed cell ratio A sample was cut from the panel foamed foam and measured by a method based on ASTM D2856.

Examples 1, 2, 5-7, 9-11:
Polyether polyol A, polyether polyol B, polyether polyol C, dipropylene glycol, water, catalyst, foam stabilizer, flame retardant, dioctyl maleate or dibutyl maleate as a modification additive A polyol premix was prepared by mixing. Then, this premix and organic polyisocyanate were mixed so that it might become a compounding ratio shown in Table 1, and the composition for rigid polyurethane foam shaping | molding was obtained. About this composition, the foaming speed, the free rise density, the presence or absence of scorch, the creation of panel foaming foam, and the panel foaming density, dimensional change rate, and closed cell ratio were measured by the methods described above. The results are shown in Table 1.

Example 3:
A polyol premix was prepared by mixing polyether polyol A, polyether polyol B, polyether polyol C, dipropylene glycol, water, catalyst, foam stabilizer, and flame retardant at the mixing ratio shown in Table 1. Thereafter, the premix, the organic polyisocyanate, and dioctyl maleate as a modifying additive were mixed so as to have a blending ratio shown in Table 1 to obtain a rigid polyurethane foam molding composition. With respect to the composition, the foaming rate and the presence or absence of scorch, the creation of panel foamed foam, and the measurement of panel foaming density, dimensional change rate, and closed cell ratio were performed by the methods described above. The results are shown in Table 1.

Example 4:
A polyol premix was prepared by mixing polyether polyol A, polyether polyol B, polyether polyol C, dipropylene glycol, water, catalyst, foam stabilizer, and flame retardant at the mixing ratio shown in Table 1. On the other hand, an organic polyisocyanate mixture was prepared by mixing dioctyl maleate as a modifying additive with an organic polyisocyanate at a blending ratio shown in Table 1. Then, this premix and this mixture were mixed so that it might become a compounding ratio shown in Table 1, and the composition for rigid polyurethane foam shaping | molding was obtained. With respect to the composition, the foaming rate and the presence or absence of scorch, the creation of panel foamed foam, and the measurement of panel foaming density, dimensional change rate, and closed cell ratio were performed by the methods described above. The results are shown in Table 1.

Example 8:
Polyether polyol A, polyether polyol C, dipropylene glycol, water, catalyst, foam stabilizer, flame retardant, dioctyl maleate or dibutyl maleate as a modifying additive are mixed at a blending ratio shown in Table 1 to obtain a polyol pre-polymer. A mix was prepared. Then, this premix and organic polyisocyanate were mixed so that it might become a compounding ratio shown in Table 1, and the composition for rigid polyurethane foam shaping | molding was obtained. About this composition, the foaming speed, the free rise density, the presence or absence of scorch, the creation of panel foaming foam, and the panel foaming density, dimensional change rate, and closed cell ratio were measured by the methods described above. The results are shown in Table 1.

Comparative Example 1:
A polyol premix was prepared by mixing polyether polyol A, polyether polyol B, polyether polyol C, dipropylene glycol, water, catalyst, foam stabilizer, and flame retardant at the mixing ratio shown in Table 2. Then, this premix and organic polyisocyanate were mixed so that it might become a compounding ratio shown in Table 2, and the rigid polyurethane foam molding composition was obtained. With respect to the composition, the foaming rate and the presence or absence of scorch, the creation of panel foamed foam, and the measurement of panel foaming density, dimensional change rate, and closed cell ratio were performed by the methods described above. The results are shown in Table 2.

Comparative Examples 2-5:
Polyether polyol A, polyether polyol B, polyether polyol C, dipropylene glycol, water, catalyst, foam stabilizer, flame retardant, dioctyl maleate as a modifying additive are mixed according to the blending ratio shown in Table 2, and polyol A premix was formulated. Then, this premix and organic polyisocyanate were mixed so that it might become a compounding ratio shown in Table 2, and the rigid polyurethane foam molding composition was obtained. With respect to the composition, the foaming rate and the presence or absence of scorch, the creation of panel foamed foam, and the measurement of panel foaming density, dimensional change rate, and closed cell ratio were performed by the methods described above. The results are shown in Table 2.

Polyether polyol A in Table 1 and Table 2 (corresponding to (b-1)): “PP-4000” (polypropylene glycol, functional group number = 2, hydroxyl value = 28 (mgKOH / g) manufactured by Sanyo Chemical Industries, Ltd. ))
Polyether polyol B: “GP-3000” manufactured by Sanyo Chemical Industries, Ltd. (polypropylene polyol, number of functional groups = 3, hydroxyl value = 56 (mgKOH / g))
Polyether polyol C: “EL-410NE” manufactured by Asahi Glass Co., Ltd. (polyethylene polyol, number of functional groups = 4, hydroxyl value = 410 (mgKOH / g))
Catalyst: Mixture consisting of the following (1) / (2) = 3/7 (mass ratio): (1) “TOYOCAT ET” manufactured by Tosoh Corporation, (2) “Kaolinizer No. 10” manufactured by Kao Corporation
Foam stabilizer: “SF2936F” manufactured by Toray Dow Corning Silicone Co., Ltd.
Flame retardant: “Phiroll PCF” manufactured by Akzo Nobel
Organic polyisocyanate: Polymeric MDI having the following composition (a) (b) (c) (isocyanate group content = 31.0%, viscosity = 180 cps / 25 ° C.)
(A) The total of 2,4′-MDI having two benzene rings and 2,2′-MDI is 1% by mass,
(B) 33% by mass of 4,4′-MDI having two benzene rings,
(C) 66% by mass of polymethylene polyphenylene polyisocyanate having three or more benzene rings

As shown in Table 1, a specific amount of dioctyl maleate or dibutyl maleate is introduced as a low molecular weight compound having an unsaturated bond and a carbonyl group adjacent to each other with a molecular weight of less than 500, an isocyanate index of less than 100, and a molecular weight of 2000. Regardless of the form of introduction, a foam in which a specific amount of polypropylene glycol of ˜5000 is introduced, no trace of scorch is observed, and the foam density is less than 30 kg / m ³ dense, Excellent dimensional change rate was shown. On the other hand, as shown in Table 2, when any of the factors constituting the present invention was applied, generation of scorch and deterioration of the dimensional change rate were observed.

The molding composition according to the present invention is extremely excellent in obtaining a continuous rigid polyurethane foam having no low scorch generation and low density (particularly less than 30 kg / m ³ ). The conventional manufacturing method can be easily obtained by a conventionally known foaming device without using a special device.

Because of such excellent advantages, the rigid continuous polyurethane foam molding composition obtained by the present invention is suitable as an injecting agent used in the production of building materials such as bay windows, door panels, wall panels, and floor panels. Can be used. Of course, the present invention can be used greatly in other applications where a rigid continuous polyurethane foam which does not generate scorch and has excellent physical properties at a low density is required.

Claims (2)

In a rigid polyurethane foam molding composition comprising (A) an organic polyisocyanate, (B) a polyol, (C) a catalyst, (D) a modifying additive, (E) a foam stabilizer, and (F) water as a foaming agent. (B) 5 to 30 parts by mass of a polypropylene glycol (b-1) having a molecular weight of 2000 to 5000 as a polyol is used relative to 100 parts by mass of the (B) polyol, and (D) a maleate having a molecular weight of less than 500 as a modifying additive. The hard ester having 0 to 75% closed cell rate, characterized in that 0.01 to 20 parts by mass of the acid ester is used with respect to 100 parts by mass of the polyol (B), and the isocyanate index in the composition is less than 100 Polyurethane foam molding composition. A method for producing a rigid polyurethane foam having a closed cell ratio of 0 to 75%, wherein the molding composition according to claim 1 is used.