JPH0334767B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a urethane-modified polyisocyanurate foam, and more particularly to a method for producing a urethane-modified polyisocyanurate foam, which is characterized by using a specific polyol mixture. Polyisocyanurate foam is a hard foam with excellent heat resistance and flame resistance obtained by polymerizing a polyisocyanate compound in the presence of a blowing agent and an isocyanate trimerization catalyst. However, this foam has extremely low brittleness and is difficult to put into practical use.
Usually, it is a urethane-modified polyisocyanurate foam in which urethane bonds are introduced using a small amount of polyol together with a polyisocyanate compound. The amount of polyol used is usually a ratio of isocyanate groups to hydroxyl groups of about 2 or more. Generally, the smaller the amount of polyol used, the less the brittleness improving effect, and conversely, the larger the amount of polyol used, the lower the heat resistance and flame resistance, and the more easily flammable it becomes. Changes in these physical properties also vary depending on the type of polyol. Therefore, there is a need for a polyol that has a higher brittleness improving effect, less decrease in heat resistance and flame resistance, and higher flame retardancy when used in the same amount. Conventionally known polyols include polyhydric alcohols such as ethylene glycol, propylene glycol, and trimethylolpropane, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, polyhydric alcohols, polyhydric phenols, and amines containing alkylene as an initiator. Examples include relatively low molecular weight polyether polyols obtained by adding oxides, relatively low molecular weight polyester polyols, and combinations of these low molecular weight polyols and relatively high molecular weight polyether polyols. However, in many cases, these polyols do not necessarily have sufficient desired properties, and polyols with even better performance are desired. In addition to the ability to improve the physical properties of the foam described above, polyols are often required to have other characteristics as well. One of them is the compatibility problem when using halogenated hydrocarbon blowing agents. Relatively hydrophilic polyols such as polyhydric alcohols, polyethylene glycol, polyether polyols with high oxyethylene group content, and polyester polyols have low compatibility with blowing agents, and mixtures of these and blowing agents will cause phase separation. The problem is that it is easy to do. According to studies by the present inventors, polyester polyols and polyester ether polyols with a high content of aromatic nuclei have good compatibility with blowing agents and also have good heat resistance and flame resistance. Therefore, when we further investigated the urethane-modified polyisocyanurate foam obtained using such polyurethane, we found that there is room for further improvement in certain applications. In applications such as heat insulation panels, adhesion between the urethane-modified polyisocyanate foam and a substrate such as a metal may be required. When a raw material mixture capable of forming a urethane-modified polyisocyanurate foam in contact with a substrate (hereinafter referred to as a foamable stock solution) is foamed and cured, the substrate and the resulting foam are usually relatively firmly adhered to each other. However, when the above-mentioned polyol having an aromatic nucleus is used, the adhesive strength between the foam and the substrate is not necessarily sufficient. The present inventor conducted various research studies to produce a urethane-modified polyisocyanurate foam that uses a polyol having an aromatic nucleus and has good adhesion to a substrate. It has been found that by doing so, it is possible to improve the adhesion to the substrate without reducing the properties of the polyol having an aromatic nucleus. The gist of the present invention is to form a hard urethane by reacting a polyol mixture and an excess polyisocyanate compound with respect to the polyol mixture in the presence of additives such as an isocyanate trimerization catalyst and a blowing agent. In the method for producing a modified polyisocyanurate foam, the polyol mixture is a mixture of about 25 to 95% by weight of the following aromatic polyol and about 75 to 5% by weight of a divalent to trivalent oxyalkylene polyol with a hydroxyl value of about 50 to 1100. A method for producing a urethane-modified polyisocyanurate foam, characterized in that it is a polyol mixture containing as a main component, aromatic polyol: containing aromatic polycarboxylic acid residues and/or polyhydric phenol residues,
It is a polyester or polyester ether polyol whose total amount is about 10% by weight or more and whose average hydroxyl value is about 100 to 500. First, the aromatic polyol in the present invention will be explained. Aromatic polyols essentially contain aromatic polycarboxylic acid residues and/or polyhydric phenol residues. Preferably, it is a polyol that essentially contains an aromatic polycarboxylic acid residue, that is, a polyol that contains an aromatic polycarboxylic acid residue or an aromatic polycarboxylic acid residue and a polyhydric phenol residue. In the aromatic polyol, the total amount of aromatic polycarboxylic acid residues and polyhydric phenol residues must be about 10% by weight or more, preferably about 10% by weight or more.
20% by weight or more, especially about 30% by weight or more. There is no particular upper limit, but it is usually about 60% by weight or less, particularly about 50% by weight or less. In the present invention, aromatic polycarboxylic acid residues refer to aromatic polycarboxylic acids from which the hydroxyl group of the carboxyl group has been removed; for example, phthalic acid residues have a molecular weight of 164
It is. Similarly, a polyvalent phenol residue refers to a polyvalent phenol from which the hydrogen atom has been removed from the phenolic hydroxyl group; for example, a bisphenol A residue has a molecular weight of 226. In addition, the polyester polyol in the present invention refers to a reaction product of a polycarboxylic acid or its acid derivative and a polyol such as a polyhydric alcohol or a derivative thereof, and a polyester ether polyol refers to the former two and a reaction product of an alkylene oxide or the like. It refers to a reaction product with a monoepoxide, and these three may be reacted at the same time.
However, in the present invention, the polyol to be reacted with the above acid or its derivative is polyhydric phenol.
Polyols obtained by reacting monoepoxides such as alkylene oxides in advance, such as monoepoxide adducts, may be used, but polyols obtained by reacting polyols obtained by reacting monoepoxides with acids or acid derivatives are polyesters. Polyols obtained by reacting monoepoxides after or simultaneously with polyester formation are classified as polyester ether polyols. In the following description of the polyol manufacturing method, (aromatic) polycarboxylic acids, etc. refer to (aromatic) polycarboxylic acids and their reactive acid derivatives such as anhydrides and acid halides, and polyhydric alcohols, etc. Refers to polyhydric alcohols, polyalkylene glycols, polyether polyols, and other compounds having two or more alcoholic hydroxyl groups. Further, the polyhydric phenol-monoepoxide adduct is one type of polyhydric alcohol or the like mentioned here. In the present invention,
Aromatic polyols are polyester polyols obtained by reacting polycarboxylic acids, etc. with polyhydric alcohols, or polyester ether polyols obtained by reacting polycarboxylic acids, etc., polyhydric alcohols, etc., and monoepoxides. Consisting of As the polycarboxylic acid, aromatic polycarboxylic acids and the like are particularly preferred, but a small amount of non-aromatic polycarboxylic acids and the like may also be used in combination. As the polyhydric alcohol, polyhydric alcohol-monoepoxide adducts, polyhydric alcohols and polyether polyols having a molecular weight of about 400 or less are preferred. Particularly preferred polyhydric alcohols are polyhydric phenol-monoepoxide adducts, dihydric to trihydric alcohols having 2 to 6 carbon atoms, polyethylene glycol with a degree of polymerization of 4 or less, and polypropylene glycol with a degree of polymerization of 3 or less. That is, by excluding the polyhydric phenol-monoepoxy adduct and using a low molecular weight polyhydric alcohol, the proportion of aromatic polycarboxylic acid residues, etc. can be increased. In the present invention, polyester ether polyol is most preferable as the aromatic polyol in terms of improving the heat resistance and flame resistance of the foam. This polyester ether polyol is produced by reacting a polycarboxylic acid, etc., a polyhydric alcohol, etc., and a monoepoxide almost simultaneously, but it may also be produced by first reacting the former two and then reacting the epoxide. The reaction ratio of polyhydric alcohol, etc. to polycarboxylic acid, etc. is approximately 1 equivalent of the former to 1 equivalent of the latter.
0.5 to 2 equivalents, especially 0.7 to 1.5 equivalents, most preferably
1.0±0.2 equivalent is suitable. The reaction ratio of monoepoxide is approximately 0.5 per mole of polycarboxylic acid, etc.
mol or more, especially about 1 to 10 mol, most preferably about
2.0 to 5.0 mol is suitable. When the aromatic polyol is a polyester polyol, it is preferably one obtained by reacting a polycarboxylic acid or the like with approximately an equivalent to a slightly excess amount of a polyhydric alcohol or the like. Although the acid value of these aromatic polyols is not particularly limited, it is preferably about 2.0 or less, particularly about 1.0 or less. Further, in the production of aromatic polyols, reaction conditions are not particularly limited, but the reaction temperature is preferably about 160°C or less, particularly about 60 to 140°C. Further, a catalyst for adding monoepoxide or a catalyst for forming polyester may be used in the reaction. Suitable catalysts for monoepoxide addition include alkali catalysts such as potassium hydroxide and sodium hydroxide, tertiary amines, etc., and metal alkoxide catalysts such as tetrabutyl titanate are suitable for polyester formation catalysts. be. As the above-mentioned aromatic polycarboxylic acids, aromatic dicarboxylic acids and their anhydrides are particularly preferable, such as phthalic acid, phthalic anhydride, isophthalic acid,
Terephthalic acid is preferred, with phthalic acid or phthalic anhydride being particularly preferred. Suitable non-aromatic polycarboxylic acids include maleic acid, fumaric acid, adipic acid, hettic acid, and anhydrides thereof. Further, these polycarboxylic acids and the like may contain a halogen or the like. Among polyhydric alcohols, etc., compounds obtained by adding about 2 to 4 moles of monoepoxide to 1 mole of dihydric phenol are preferred as the polyhydric phenol-epoxide adduct.
Suitable divalent phenols include bisphenol A, bisphenol S, bisphenol F, and their halides, with bisphenol A being particularly preferred. Other polyhydric phenols include phenol-formaldehyde initial condensates. Among polyhydric alcohols, polyhydric alcohols include ethylene glycol, propylene glycol,
4-butanediol, glycerin, trimethylolpropane, etc. are preferred; the polyalkylene glycol is preferably di-, tri- or tetraethylene glycol or dipropylene glycol; the polyether polyol is 2-8
A compound obtained by adding a monoepoxide to a polyhydric alcohol is preferred. The monoepoxide is preferably an alkylene oxide such as ethylene oxide or propylene oxide, and both may be used in combination. Furthermore, a halogen-containing alkylene oxide or styrene oxide can also be used together with these alkylene oxides or alone. In addition, the hydroxyl value of the aromatic polyol in the present invention needs to be about 100 to 500, and particularly preferably about 120 to 400. The oxyalkylene polyol, which is the second polyol in the present invention, has a hydroxyl value of about 50 to 1100.
It is a divalent or trivalent polyol. This polyol is polyalkylene glycol or
It is a polyether polyol obtained by adding a monoepoxide to a trivalent initiator. As the polyalkylene glycol, polyethylene glycol or polypropylene glycol having a degree of polymerization of 2 or more is preferable, and polyethylene glycol having a degree of polymerization of 3 to 25 is particularly preferable. The polyether polyol is preferably a compound having a polyoxyethylene, polyoxypropylene, or poly(oxyethylene/oxypropylene) chain, and may also be a compound having a poly(oxytetramethylene) chain. Particularly preferably 2 to 3 of the above polyhydric alcohols, alkanolamines, etc.
Ethylene oxide and/or
Alternatively, a compound obtained by adding propylene oxide is preferable. This polyether polyol may further contain groups derived from halogen-containing alkylene oxide or styrene oxide as described above. Preferred polyether polyols are polyether polyols containing at least 15% by weight oxyethylene groups. In addition, the more preferable hydroxyl value of the oxyalkylene polyol is approximately
It is 100-600. The polyol mixture in the present invention may contain two or more of the above aromatic polyols or polyoxyalkylene polyols. The mixing ratio of both polyols is approximately 25 to 95% by weight for the former and approximately 75 to 95% for the latter.
5% by weight, particularly a combination of about 40 to 80% by weight of the former and about 20 to 60% by weight of the latter. Moreover, the polyol mixture may contain polyols other than both polyols in addition to both polyols. The amount thereof is preferably equal to or less than the total amount of both polyols, particularly preferably 1/4 or less of both polyols, but its use is not essential and substantially only both polyols are sufficient. It is. As the polyisocyanate compound which is the main raw material for the urethane-modified polyisocyanurate foam in the present invention, aromatic polyisocyanate compounds are preferable, but aliphatic or alicyclic polyisocyanate compounds may also be used as part or all of them. can. Preferred aromatic polyisocyanate compounds include, but are not limited to, polymethylene polyphenyl isocyanate, diphenylmethane diisocyanate, and tolylene diisocyanate. Modified products of these aromatic polyisocyanate compounds, such as prepolymer-type modified products, carbodiimide-modified products, and urea-modified products, can also be used. The amount of polyisocyanate compound used is the isocyanate group/
The excess amount is preferably 1.5 or more, particularly 2 to 5 in terms of the ratio of the number of hydroxyl groups. In addition, when expressed in weight ratio, 5 to 75 parts by weight of the polyol mixture to 100 parts by weight of the polyisocyanate compound, especially 10 parts by weight.
It is preferably 50 parts by weight. Various isocyanate trimerization catalysts can be used. For example, metal (e.g., alkali metals, lead, iron, etc.) salts of carboxylic acids, tertiary amines such as dialkylaminoalkylphenols and trialkylamines, inorganic bases such as caustic potash and soda carbonate, alkali metal alcoholates, triethylphosphine, etc. Examples include phosphine and quaternary ammonium salts. In particular, alkali metal salts and quaternary ammonium salts of fatty acids having 1 to 18 carbon atoms are suitable. The blowing agent is preferably a halogenated hydrocarbon blowing agent or a combination thereof with water. Examples of the halogenated hydrocarbon blowing agent include trichlorofluoromethane, dichlorodifluoromethane, and methylene chloride. The amount of catalyst and blowing agent used is not particularly limited, but
Suitable amounts are 0.01 to 5 parts by weight, and 5 to 50 parts by weight of the blowing agent. In the present invention, four essential raw materials for the urethane-modified polyisocyanurate foam are a polyol mixture, a polyisocyanate compound, an isocyanate trimerization catalyst, and a blowing agent, but other raw materials may be used in combination. Other additives which are preferably used include foam stabilizers. As the foam stabilizer, silicone foam stabilizers such as those used in the production of polyurethane foams such as polysiloxane-polyoxyalkylene block copolymers and polysiloxanes are preferred. In addition, various additives such as a urethanization catalyst, reinforcing fibers, fillers, flame retardants, colorants, and stabilizers may be used as necessary. The present invention will be specifically explained below with examples, etc.
The present invention is not limited to these examples.
In addition, the polyols used were as follows. <Aromatic polyol> Polyol A Bisphenol A- obtained by adding 3 moles of propylene oxide to 1 mole of bisphenol A
60% by weight of propylene oxide adduct, 20 parts by weight of phthalic anhydride, and 20 parts by weight of ethylene oxide are reacted at 120°C for 2 hours in the presence of 0.1 part by weight of potassium hydroxide to cause a small amount of unreacted material to be removed. A polyester ether polyol with a hydroxyl value of 200. Polyol B A polyester ether polyol with a hydroxyl value of 300 obtained by reacting 25 parts by weight of 1,4-butanediol, 40 parts by weight of phthalic anhydride, and 35 parts by weight of ethylene oxide in the same manner as Polyol A. Polyol C A polyester ether polyol with a hydroxyl value of 260 obtained by reacting 30 parts by weight of dipropylene glycol, 35 parts by weight of phthalic anhydride, and 35 parts by weight of propylene oxide in the same manner. Polyol D Polyester ether polyol with a hydroxyl value of 300 obtained by reacting 60 parts by weight of a polyether polyol with a hydroxyl value of 450 consisting of a pentaerythritol-propylene oxide adduct, 20 parts by weight of phthalic anhydride, and 20 parts by weight of propylene oxide. . Polyol E A polyester polyol with a hydroxyl value of 320 obtained by reacting a mixture of 80% by weight of phthalic acid and 20% by weight of adipic acid with ethylene glycol. <Oxyalkylene polyols and other polyols> Polyol a: Ethylene glycol b: Diethylene glycol c: Tetraethylene glycol d: Polyethylene glycol with a molecular weight of 400 e: Polyethylene glycol with a molecular weight of 1000 f: Glycerin with a molecular weight of 1000 Propylene oxide adduct polyol g: Polyether triol with an oxyethylene group content of 30% by weight and a molecular weight of 1500 obtained by adding propylene oxide and ethylene oxide to glycerin h: Oxyethylene group content obtained in the same manner as polyol g 20% by weight, polyether triol with a molecular weight of 3000 〃 i: Examples of monoethanolamine-propylene oxide adducts with a molecular weight of 500 The above polyols A to E, and polyols b to
A total of 20 parts by weight of i, 1.0 parts by weight of a quaternary ammonium salt catalyst (trade name "Dabco TMR", sold by Sankyo Air Products Co., Ltd.) as a catalyst, and a silicone foam stabilizer (trade name "SH-193", Toray). sold by Silicone Co., Ltd.)
2.0 parts by weight, and trichlorofluoromethane 23
Parts by weight of the mixture and 80 parts by weight of polymethylene polyphenylisocyanate (product name "PAPI-135", sold by Kasei-uption Co., Ltd.) were mixed at a liquid temperature of 20°C, and the mixture was placed in a 200 mm x 200 mm x 200 mm wooden box. The foam was charged and allowed to foam freely, and the flammability of the foam was examined one day later. On the other hand, a foamable mixture having the same formulation as above was charged into a 300 mm x 300 mm x 30 mm mold in which 0.27 mm thick galvanized colored iron plates were placed on both the upper and lower surfaces, and foamed and hardened. One day later, the foam was cut in the thickness direction with a hand saw (trade name "U-300", manufactured by Luxo Co., Ltd.). The adhesion between the foam and the iron plate was examined based on the degree of peeling and falling off of the iron plate at that time. Table 1 below shows the combined ratio of the two polyols in the above formulation, free foam density, flammability (burning distance according to JIS A-9514), and adhesion results according to the following judgment. Judgment of adhesion: ◎ Peeling of steel plate is within 5 mm from the cut surface 〇 The peeling of the steel plate is within 10 mm from the cut surface Δ The peeling of the steel plate is within 30 mm from the cut surface × The peeling of the steel plate is 30 mm or more from the cut surface (including falling off) Comparison Example The same test as in Example was conducted for polyols A to E alone or in combination with polyol a. The results are also shown in Table 2 below.

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Claims (1)

[Claims] 1. Producing a hard urethane-modified polyisocyanurate foam by reacting a polyol mixture and an excess polyisocyanate compound with respect to the polyol mixture in the presence of additives such as an isocyanate trimerization catalyst and a blowing agent. In the method, the polyol mixture contains about 25 to 95% by weight of the following aromatic polyol:
A method for producing a urethane-modified polyisocyanurate foam, which is a polyol mixture whose main component is a mixture of about 50 to 1100 hydroxyl value and about 75 to 5% by weight of a divalent to trivalent oxyalkylene polyol. Aromatic polyol: contains aromatic polycarboxylic acid residues and/or polyhydric phenol residues,
A polyester or polyester ether polyol whose total content is about 10% by weight or more and whose average hydroxyl value is about 100 to 500. 2. The aromatic polyol is characterized in that the aromatic polycarboxylic acid residue is essential, and the total amount of the aromatic polycarboxylic acid residue and polyhydric phenol residue is about 20 to 60% by weight. The method according to claim 1.