JPS6317284B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a urethane-modified polyisocyanurate foam, and particularly to a method for producing a urethane-modified polyisocyanurate foam characterized by using a specific polyol. 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. On the other hand, highly hydrophobic polyols such as polyether polyols with a high content of oxypropylene groups have high compatibility with blowing agents, but have the problem that the resulting foam tends to have low physical properties such as flame retardancy. . As a means to solve these two problems, a method has been proposed in which a polyester polyol and a polyether polyol obtained by adding propylene oxide to a polyhydric alcohol are used together (see Japanese Patent Publication No. 57-22052). However, in this method, the compatibility between the polyester polyol and the polyether polyol is low, and the blowing agent tends to dissolve in the polyether polyol, so it cannot be said that the above-mentioned compatibility problem has been sufficiently solved. The present inventor conducted various research studies in order to find a polyol that is excellent in improving the physical properties of urethane-modified polyisocyanurate foam, and also examined polyols from the viewpoint of compatibility with the above-mentioned blowing agent. As a result, we found that polyester ether polyols with a balance of hydrophilicity and hydrophobicity are excellent in improving the physical properties of foams. This polyol has a good balance between hydrophilicity and hydrophobicity, and therefore has excellent compatibility with blowing agents. The present invention relates to a method for producing a polyurethane-modified polyisocyanurate foam using this polyester ether polyol, that is, at least a polyol, an excess polyisocyanate compound with respect to the polyol, an isocyanate trimerization catalyst, and a blowing agent. In a method for producing a urethane-modified polyisocyanurate foam using four essential raw materials, at least a part of the polyol is a polyhydric phenol-alkylene oxide adduct, a polyhydric alcohol, and a polyhydric alcohol-alkylene oxide adduct. A hydroxyl value of about 100 to 500 obtained by reacting at least one polyol (a) selected from polyhydric carboxylic acid or its anhydride (b) and simultaneously or subsequently reacting an alkylene oxide (c). polyester ether polyol, in which a polyhydric phenol-alkylene oxide adduct is used as the polyol (a), or an aromatic polyhydric carboxylic acid or its anhydride is used as the polyhydric carboxylic acid or its anhydride (b). 1. A method for producing a urethane-modified polyisocyanurate foam, which is characterized in that a polyester ether polyol is used. First, the polyester ether polyol in the present invention will be explained. First, special definitions in the present invention will be explained. Among polyhydric alcohols, alkylene glycols such as ethylene glycol and propylene glycol can be considered to have an oxyalkylene group, but in the present invention, these alkylene glycols are classified as polyhydric alcohols. In addition, polyethylene glycols such as diethylene glycol and triethylene glycol, polypropylene glycols such as dipropylene glycol and tripropylene glycol,
and other polyalkylene glycols are classified as polyhydric alcohol-alkylene oxide adducts in the present invention, even though they are not actually obtained by addition reactions of alkylene oxides. Therefore, for example, diethylene glycol is regarded as a compound in which one molecule of ethylene oxide is added to one molecule of ethylene glycol, and dipropylene glycol is regarded as a compound in which one molecule of propylene oxide is added to one molecule of propylene glycol. Further, a compound obtained by adding an equivalent or more amount of alkylene oxide to a polyhydric phenol can be considered to be a type of polyhydric alcohol, but in the present invention it is regarded as a polyhydric phenol-alkylene oxide adduct. An oxyalkylene group is a group derived from alkylene oxide, but there are exceptions as mentioned above. The polyester ether polyol in the present invention has at least three residues of polyhydric phenols and/or polyhydric alcohols, residues of polyhydric carboxylic acids, and oxyalkylene groups under the above definition.
It is a polyester ether polyol which essentially includes a species structural unit and further includes either a residue of a polyhydric phenol or a residue of an aromatic polycarboxylic acid. The hydroxyl value must be within the range of about 100 to 500, preferably about 150 to 400.
is within the range of The acid value of the polyester ether polyol is preferably 2 or less, particularly 1 or less.
In the polyester ether polyol, the average proportion of each structural unit is not particularly limited. However, it is usually appropriate to use 0.5 to 2.0, especially 0.8 to 1.5, polyhydric carboxylic acid residues for each polyhydric phenol and/or polyhydric alcohol residue. Similarly, the number of oxyalkylene groups is 1.5 or more, particularly 2.0 or more, which is less than the amount by which a polyester ether polyol that does not fall below the lower limit of the hydroxyl value mentioned above is obtained. Further, the number of oxyalkylene groups is preferably 1.0 or more, particularly 2.0 or more relative to the total number of polyhydric phenol and/or polyhydric alcohol residues and polyhydric carboxylic acid residues. In terms of foam properties, polyester ether polyols containing many ester groups, oxyethylene groups, and ethylene glycol residues are preferred. On the other hand, from the viewpoint of compatibility with the blowing agent, polyester ether polyols containing a large number of oxyalkylene groups having 3 or more carbon atoms and polyhydric alcohol residues having a large number of carbon atoms are preferable;
It has been found that aromatic nuclei such as benzene nuclei enhance the compatibility with blowing agents. Therefore, the polyester ether polyol preferably contains an aromatic nucleus and also contains an oxyethylene group and/or an ethylene glycol residue. Therefore, it is preferable that the residue of the polycarboxylic acid is a residue of an aromatic polycarboxylic acid. Furthermore, it is preferable that the residues of polyhydric phenols and/or polyhydric alcohols are at least residues of polyhydric phenols. Of course, it may be a residue of a polyhydric alcohol (not a polyhydric phenol-alkylene oxide adduct) having an aromatic nucleus, but a residue of a polyhydric phenol is more common and preferred. It is preferable that at least a portion of the oxyalkylene group is an oxyethylene group. Among all oxyalkylene groups,
Preferably the number ratio is about 30-100%, especially about 40-80
% is preferably an oxyethylene group. Therefore, the most preferred polyester ether polyols contain residues of polyhydric phenols, residues of aromatic polycarboxylic acids, and at least about 30% by number,
Preferably, it is a polyester ether polyol containing at least about 40% oxyalkylene groups containing oxyethylene groups, and then containing either a residue of polyhydric phenols or an aromatic polycarboxylic acid, When the polyhydric alcohol residue is contained, it is an ethylene glycol residue, and the oxyalkylene group is preferably a polyester ether polyol containing an oxyethylene group in the same range as above. The third most preferred one contains a residue of a polyvalent phenol and/or a residue of a polyvalent carboxylic acid containing an aromatic nucleus, and does not contain an oxyethylene group or contains an oxyethylene group below the above range. It is a polyester ether polyol consisting of oxyalkylene groups. The polyhydric phenols and polyhydric alcohols are suitably divalent or higher, particularly divalent to octavalent, but preferably divalent to trivalent, with dihydric being particularly preferred. As the polycarboxylic acid, divalent to tetravalent ones are suitable, but divalent carboxylic acids are particularly suitable.
Preferably, the one with the highest value. The oxyalkylene group preferably has 2 to 4 carbon atoms, and is particularly composed of only oxyethylene or oxypropylene groups,
A combination of oxyethylene and oxypropylene groups is preferred. In addition, the total content of aromatic polycarboxylic acid residues and polyhydric phenol residues in the polyester ether polyol is about 10% by weight or more, especially about 20% by weight or more.
It is preferably at least % by weight. The upper limit is suitably about 55% by weight, but it may be higher if possible. The residue of aromatic polyhydric carboxylic acid refers to the group obtained by removing the hydrogen atom of the carboxyl group of aromatic polyhydric carboxylic acid, and the term polyvalent phenol residue refers to the group obtained by removing the hydrogen atom of the phenolic hydroxyl group of polyhydric phenol. Refers to residue. Therefore, it is preferable that a polyester ether polyol having no polyhydric phenol residues has an aromatic polycarboxylic acid residue within the above range, and a polyester ether polyol having no aromatic polycarboxylic acid residues is preferable. The polyol preferably has polyvalent phenol residues within the above range. Of course, when both residues are present, it is preferable that the total of them is within the above range. The polyester ether polyol in the present invention includes a polyhydric phenol-alkylene oxide adduct, a polyhydric alcohol, and a polyhydric alcohol-
It is produced by reacting a polyol (a) selected from alkylene oxide adducts with a polyhydric carboxylic acid or its anhydride (b), and simultaneously or afterwards reacting an alkylene oxide (c). The product obtained by the above method is often a mixture containing polyester ether polyol as a main component (which itself is often not a single compound but a mixture) and other by-products and unreacted substances.
However, if the presence of carboxylic acid groups is below the above-mentioned limit, it can be used as is. Of course, if necessary, by-products and unreacted substances may be removed to some extent. Furthermore, two or more types of each raw material may be used. In particular, the alkylene oxide (c) that is reacted with polyhydric phenols or polyhydric alcohols in advance may be different from the alkylene oxide (c) that is reacted simultaneously with or after esterification. The reaction for producing polyester ether polyols is usually carried out under heating. Although the temperature varies depending on the type of raw material, it is usually 160°C or less, particularly 60 to 140°C.
At high temperatures, the reaction can be carried out without catalyst.
However, it is preferable to use at least one esterification catalyst or a catalyst that promotes the alkylene oxide addition reaction. As the catalyst, for example, a tertiary amine catalyst such as triethylamine, a caustic alkali catalyst such as potassium hydroxide, a metal alkoxide catalyst such as Ti(OC ₄ H ₉ ) ₄ , etc. can be used. The amount of catalyst used is not particularly limited, but is suitably 0.01 to 1% by weight. The reaction ratio of polycarboxylic acids or their anhydrides (b) and alkylene oxide (c) to polyol (a) is preferably within the range of the above-mentioned structural unit ratios, but in reality, by-products and unreacted substances are Therefore, the two may not necessarily match. Further, the oxyalkylene group in the structural unit means both the oxyalkylene group derived from the alkylene oxide (c) and the oxyalkylene group in the polyol (a). The amount of polycarboxylic acids or their anhydrides to be used per equivalent of polyol (a) is suitably 0.5 to 2.0 equivalents, particularly 0.8 to 1.5 equivalents, and preferably approximately equal equivalents. Similarly, the amount of alkylene oxide (c) used per 1 equivalent of polyol (a) is 0.5
The amount is equal to or more than the equivalent amount and does not fall below the lower limit of the hydroxyl value. More preferably, it is 1 to 5 equivalents. The amount of alkylene oxide added in advance to the polyhydric phenol is approximately equal to or more than 1 equivalent per equivalent of the polyhydric phenol, particularly 1 to 3 equivalents. 2 mol or more, particularly 2 to 6 mol, is suitable, and bis(hydroxyalkyl)-modified dihydric phenol, which is an equivalent adduct, is particularly preferred. In the case of polyhydric alcohols, the amount of alkylene oxide added is suitably approximately 0.5 equivalent or more. That is, according to the above definition, for example, diethylene glycol is considered to be a reaction product of ethylene glycol and 0.5 equivalent of ethylene oxide. The preferred usage amount is 0.5
~2 equivalents. Preferred reaction raw materials are the following compounds. As the polyhydric carboxylic acids, their anhydrides are more preferable than those listed below. Polyvalent phenols: bisphenol A, bisphenol S (bishydroxyphenyl sulfone),
Bisphenol F (bishydroxyphenylmethane) Polyhydric phenol-alkylene oxide adduct: A compound obtained by adding an equivalent amount (ie, twice the mole) or more of ethylene oxide and/or propylene oxide to the above three compounds. Polyhydric alcohols: ethylene glycol, propylene glycol, 1,4-butanediol Polyhydric alcohol-alkylene oxide adducts: diethylene glycol, dipropylene glycol Polyhydric carboxylic acids: phthalic acid, maleic acid, succinic alkylene oxide: ethylene oxide, propylene Oxide Other raw materials that can be used include: Polyhydric phenols: resorcin, dihydroxytoluene, bis(hydroxyphenyl) sulfide, polyhalogenated bisphenol A, polyhalogenated bisphenol S, polyhalogenated bisphenol F, phenol-formaldehyde initial condensate, alkyl-substituted phenol- Formaldehyde initial condensate polyhydric phenol-alkylene oxide adduct: A compound obtained by adding an equivalent or more amount of ethylene oxide and/or propylene oxide to the above polyhydric phenols. Polyhydric alcohols: glycerin, trimethylolpropane, pentaerythritol, dextrose, cyclohexanediol, hydrogenated bisphenol A, xylylene glycol, polyhydric alcohol-alkylene oxide adduct: poly(3 or more) ethylene glycol, poly(3 or more) ) A compound obtained by adding ethylene oxide and/or propylene oxide to propylene glycol, the above polyhydric alcohols, the above preferred polyhydric alcohols, and the above preferred polyhydric alcohol-alkylene oxide adducts. Polyhydric carboxylic acids: isophthalic acid, terephthalic acid, toluene dicarboxylic acid, trimellitic anhydride, tetrachlorophthalic anhydride, oxalic anhydride, adipic acid, alkylene oxide: butene oxide The raw materials are limited to the compounds shown in the above specific examples. Moreover, two or more of the same type of these raw materials may be used in combination. In addition to alkylene oxides, halogenated alkylene oxides (e.g., epichlorohydrin and 4,4,4-trichloro-1,2-
Epoxides other than alkylene oxide, such as butene oxide) and styrene oxide, may be used in combination. Furthermore, when the halogen-containing polyester ether polyol obtained by using a compound containing a halogen among the above raw materials is used in a small amount, it rather deteriorates the physical properties of the urethane-modified polyisocyanurate foam compared to one that does not contain a halogen. Tend. Two or more types of polyester ether polyols in the present invention can be used in combination. In particular, polyester ether polyols containing the most preferred aromatic nuclei (i.e., those containing residues of polyhydric phenols and residues of aromatic polyhydric carboxylic acids) and other polyester polyols, especially the second and third
A combination with a polyester ether polyol is preferred. Of the total polyols used as raw materials for the urethane-modified polyisocyanurate foam in the present invention, at least 50% by weight,
In particular, about 70 to 100% by weight is preferably the polyester ether polyol according to the present invention. Other polyols that can be used in combination include polyhydric alcohols, polyphenols, polyhydric amines and alkanolamines, polyether polyols obtained by adding alkylene oxide to other initiators, various polyester polyols, and polyhydric alcohols. , alkanolamines, etc.
In some cases, polyols or monohydric alcohols having a low hydroxyl value (ie, high molecular weight) may also be used. Preferably, the average hydroxyl value of the mixture with the polyester ether polyol is in the range of about 100 to 600. The use of other polyols is not essential, and it is substantially preferable to use the polyester ether polyol alone in the present invention. The polyisocyanate compound which is the main raw material for the urethane-modified polyisocyanurate foam in the present invention is preferably an aromatic polyisocyanate compound, but aliphatic or alicyclic polyisocyanate compounds may also be used as a part or all. 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. When expressed in weight ratio, it is preferably 5 to 75 parts by weight, particularly 10 to 50 parts by weight of polyol per 100 parts by weight of polyisocyanate compound. 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, as raw materials for the urethane-modified polyisocyanurate foam, the four components of polyol, polyisocyanate compound, isocyanate trimerization catalyst, and blowing agent are essential raw materials, 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. Production example <Production method of polyester ether polyol> Polyester ether polyol-1 (Polyol A) 900 g of 1,4 butanediol, 1480 g of phthalic anhydride, and 4.5 g of 85% KOH pellets were charged into 5 reactors, and the temperature was raised to 120°C. Thereafter, 1220 g of ethylene oxide was introduced while maintaining the reaction temperature at 120°C. After maintaining the temperature at 120°C for 2 hours, unreacted substances were distilled off under reduced pressure. The obtained polyol has an OH value of 325 and a viscosity of
It was 2400cp/25℃. Polyester ether polyol-2 (polyol B) Dipropylene glycol in the same manner as above
1280g of phthalic anhydride, 1550g of phthalic anhydride, and 1380g of propylene oxide were reacted. The obtained polyol has an OH number of 276 and a viscosity of
It was 11,700cp/25℃. Polyester ether polyol-3 (Polyol C) Similarly, polyol 2360 is prepared by adding 3 moles of propylene oxide to 1 mole of bisphenol A.
g, phthalic anhydride 870g, ethylene oxide 780g
reacted. A polyol with an OH number of 182 and a viscosity of 153,000 cp/25°C was obtained. Polyester ether polyol-4 (Polyol D) 2700 g of a polyol prepared by adding 4 moles of propylene oxide to 1 mole of bisphenol A, 870 g of phthalic anhydride, and 780 g of ethylene oxide were reacted. A polyol with an OH value of 169 and a viscosity of 89,500 cp/25°C was obtained. Polyester ether polyol-5 (Polyol E) 1640 g of a polyol prepared by adding 4 moles of propylene oxide to 1 mole of bisphenol A, 380 g of diethylene glycol, 1060 g of phthalic anhydride, and 940 g of ethylene oxide were reacted. A polyol with an OH value of 231 and a viscosity of 15,400 cp/25°C was obtained. Polyester ether polyol-6 (Polyol F) 2700 g of a polyol prepared by adding 4 moles of propylene oxide to 1 mole of bisphenol A, 590 g of succinic anhydride, and 780 g of ethylene oxide were reacted. A polyol with an OH number of 185 and a viscosity of 29,700 cp/25°C was obtained. <Polyols for comparison> Polyether polyol (Polyol H) Propylene oxide adduct of pentaerythritol (OH value 300) Polyester polyol (Polyol I) Synthesized from 80% by weight of phthalic acid, 20% by weight of adipic acid, and ethylene glycol (OH <Compatibility comparison test> Weigh 100 g of polyol into a 300 c.c. Erlenmeyer flask and adjust the temperature to 25°C. Next, trichloromonofluoromethane (R-11) was mixed little by little, and the amount of trichlorofluoromethane added until the mixture started to become cloudy was used as a measure of compatibility. Table 1 shows the results.
Shown below.

[Table] The polyester ether polyols (polyols A to F) of the present invention have better compatibility with R-11 than simple polyester polyol I. Example <Production method of polyisocyanurate foam>

【table】

[Table] According to the foaming recipe shown in Table 2, adjust the liquid temperature.
The mixture was adjusted to 20°C, mixed, and foamed in a 200 x 200 x 200 mm wooden panel. Test results for various polyols on foaming reactivity, physical properties, heat resistance, and flame retardance of the obtained polyisocyanurate foams are shown.
Shown in 3.

【table】

[Table] It can be seen that when polyols A to G based on the present invention were used (Examples 1 to 7), the compressive strength, heat resistance, and flame retardance were excellent, and the brittleness and closed cell ratio were also good. When polyether polyol is used as in Comparative Example-1, heat resistance and flame retardance are poor. When a normal polyester polyol was used as in Comparative Example 2, no good results were observed, probably due to the poor compatibility of R-11.

Claims (1)

[Scope of Claims] 1. A method for producing a urethane-modified polyisocyanurate foam using at least four essential ingredients as essential raw materials: a polyol, a polyisocyanate compound in excess of the polyol, an isocyanate trimerization catalyst, and a blowing agent, At least one polyol (a) selected from polyhydric phenols-alkylene oxide adducts, polyhydric alcohols, and polyhydric alcohols-alkylene oxide adducts and a polyhydric carboxylic acid, as at least a part of the polyol. Alternatively, a polyester ether polyol having a hydroxyl value of about 100 to 500 obtained by reacting the anhydride (b) and simultaneously or subsequently reacting the alkylene oxide (c), which is polyesterether polyol having a hydroxyl value of about 100 to 500, A polyester ether polyol which requires either the use of a polyhydric phenol-alkylene oxide adduct, or the use of an aromatic polyhydric carboxylic acid or anhydride thereof as the polyhydric carboxylic acid or its anhydride (b). A method for producing a urethane-modified polyisocyanurate foam. 2. The method according to claim 1, wherein the oxyethylene alkylene groups present in the polyester ether polyol contain 30% or more of oxyethylene groups based on the total amount of oxyalkylene groups.