JPS631331B2 - - Google Patents

Description

Detailed Description of the Invention The present invention relates to a method for producing a urethane-modified isocyanurate foam, and by using a specific polyol and an aliphatic diol or aliphatic triol, the heat resistance and flame resistance of the polyisocyanurate foam can be improved. The purpose is to improve the brittleness and the smoothness of the foam surface during spray foaming without impairing the foam. Generally, polyisocyanurate foam exhibits excellent properties in terms of heat resistance and flame resistance, but it is extremely brittle compared to other organic foams such as rigid urethane foam, which is a major drawback in practical use. Although various methods have been proposed to improve this brittleness, a satisfactory polyisocyanurate foam has not yet been obtained due to practical problems. For example, Japanese Patent Publication No. 44-16669, British Patent No.
Although the method described in No. 1146661 attempts to improve brittleness by introducing urethane bonds into polyisocyanurate foam, the brittleness is still not sufficiently improved. In addition, KCFrisch and others have conventionally used polyfunctional polyols as polyols for urethane modification in order to maintain heat resistance, but the Journal of Cellular Plastics
In September/October 203 (1970), we are considering improving the brittleness by using aliphatic diols. However, this method results in a decrease in heat resistance and a decrease in physical property values. Mata Tokuko Showa 46-
In Publication No. 41393, a phenolic Mannitz base is used as a trimerization catalyst and a polyol is used in combination, but the effect of reducing brittleness is small. Furthermore, Japanese Patent Application Laid-open No. 47-15171 (Japanese Patent Application No. 1977-15171)
and KCFrisch K. Ashida, Journal of
In Cellular Plastics・July/Auguet 194 (1972), an oxazolidone ring-containing prepolymer with isocyanate terminals is made from isocyanate and epoxy, and the brittleness is improved by trimerizing this. In addition, this prepolymer has the disadvantage that its viscosity is very unstable. Also, as a general method for improving the brittleness of polyisocyanurate foams, urethane bonds have been introduced. As this polyol, one with as high a number of functional groups as possible is used, and as a result, the crosslinking density of the foam is improved, and the network structure is increased by trimerization of isocyanate, and the network structure is increased by crosslinking of urethane, thereby improving heat resistance. has become common knowledge. However, with this method, increasing the crosslinking density improves heat resistance, but on the other hand, the foam becomes brittle, and conversely, decreasing the crosslinking density improves the brittleness but reduces heat resistance, which is a contradictory result. . As described in Japanese Patent Publication No. 54-15600, the present inventors took into consideration the above-mentioned contradictions and found that it is extremely difficult to improve brittleness without reducing heat resistance and flame resistance by simply increasing or decreasing crosslink density. We determined that this would be difficult, and by introducing a large amount of aromatic rings into the polymer skeleton itself rather than the crosslink density, we were able to produce a low-brittle polyisocyanurate foam without sacrificing heat resistance or flame resistance. It still had some drawbacks. 1 The viscosity of the aromatic amine polyol and the aromatic diol is high, and the smoothness of the foam surface during spray foaming is insufficient. 2. Since an aromatic amine polyol is used as the main polyol, the urethane production reaction tends to take precedence over the isocyanurate reaction, which greatly inhibits the isocyanurate reaction and reduces the production rate of isocyanurate rings. Heat resistance and flame resistance are insufficient. 3. Both aromatic amine polyols and aromatic diols have high viscosity, and these polyols pose problems in handling. The inventors of the present invention have conducted intensive research to solve the above-mentioned drawbacks, and have found that the
Furthermore, we have succeeded in producing a urethane-modified isocyanurate foam that has a smooth foam surface during spray foaming. That is, the present invention relates to the production of a urethane-modified polyisocyanurate foam from an aromatic polyisocyanate, a polyol, a blowing agent, a catalyst, and a surfactant. and/or [ _n1 to _n8 : number of 1 to 7, m: number of 0 to 4, R: alkylene group], and this aromatic amine polyol is 50% of the total amount of polyols. At least 60% by weight, preferably 60% by weight
Contains ~80% by weight and has the general formula [x ₁ , x ₂ : number of 1 to 2 R′ : alkylene group] 50% of the total polyol amount
5 to 25 parts by weight of an aliphatic diol or aliphatic triol having a hydroxyl value of 300 or more, preferably 500 to 1100, per 100 parts by weight of a mixed polyol containing 5 to 25 parts by weight or less, preferably 40 to 20 weight %.
Part by weight, preferably 10 to 20 parts by weight, and the aromatic polyisocyanate is used in an amount equivalent to 2 to 10 times the total amount of the active hydrogen compound containing the above polyol, preferably 3 to 20 parts by weight.
The present invention relates to a method for producing a urethane-modified isocyanurate foam, which is characterized in that it is used in a 7-fold equivalent amount. If the equivalent ratio of the aromatic polyisocyanate to the total amount of the active hydrogen compound is less than 2, the crosslinking density (isocyanurate bond density) will be low and the heat resistance and flame resistance will be significantly reduced. Furthermore, if the equivalent ratio exceeds 10, the crosslinking density will increase and the heat resistance and flame resistance will improve, but the foam will become extremely brittle and the effects of the present invention cannot be expected. Furthermore, when the content of the aromatic amine polyol represented by the above general formula is less than 50% by weight based on the total amount of polyols, the nitrogen concentration in the mixed polyol decreases and the brittleness of the foam skin increases significantly. This phenomenon is particularly noticeable in spray foaming. That is, the brittleness of the foam skin becomes significantly greater, and the unevenness of the foam surface becomes greater. If the amount of aliphatic diol or aliphatic triol is less than 5 parts by weight, the viscosity of the polyol component will be high and the surface of the foam will have large irregularities, resulting in a decrease in heat resistance and flame resistance of the foam. Furthermore, if the amount is increased to 25 parts by weight, the number of aromatic rings inside will decrease, resulting in a marked decrease in the heat resistance of the foam. When the hydroxyl value of the aliphatic diol or aliphatic triol is less than 300, the molecular weight of the diol or triol becomes large, reducing the crosslinking density and significantly reducing the heat resistance of the foam. When an aliphatic diol or aliphatic triol is used in combination with a mixed polyol consisting of an aromatic amine polyol and an aromatic diol, heat resistance, foam surface condition, cell shape, etc. are improved compared to when each is used alone. A synergistic effect appears. If an aliphatic diol or aliphatic triol is mixed in advance with an aromatic amine polyol and/or an aromatic diol, the viscosity of the entire polyol component is significantly reduced, which is advantageous in terms of handling. In other words, aromatic amine polyols and aromatic diols have extremely high viscosities, so they must be heated to lower their viscosity when weighing or mixing with chemical components (e.g. catalysts), but aliphatic diols , triol has an OH value of 300
Above that, the viscosity is low [approximately, less than 1000CP (at 25℃)]
Therefore, if this low-viscosity diol or triol is mixed with the above-mentioned polyol, the viscosity of the mixed polyol will be significantly reduced, making it very convenient to handle. In addition, as will be described later, when producing these polyols, a reaction initiator for an aromatic amine polyol or an aromatic diol and a reaction initiator for an aliphatic diol or triol are mixed in advance, and a co-initiator (co-initiator) is used. ) is convenient to use. Aromatic amine polyols that can be used in the present invention include or One or two alkylene oxides (e.g. ethylene oxide, propylene oxide, butylene oxide, etc.) using an aromatic amine represented by as an initiator.
General formula with species or more added or It is an aromatic amine polyol having 4 to 12 functional groups represented by In the general formula, n ₁ to _{n 8} may be the same or different numbers, and R may be the same or different alkylene groups. m is a number from 0 to 4. Aromatic diols that can be used in the present invention include: A general formula in which one or more alkylene oxides (e.g. ethylene oxide, propylene oxide, butylene oxide, etc.) are added to an aromatic diol represented by the following as an initiator: It is an aromatic diol represented by x ₁ and x ₂ in the general formula are numbers from 1 to 2, and may be the same or different numbers. Examples of aliphatic diols or aliphatic triols that can be used in the present invention include water, ethylene glycol,
propylene glycol, 1,4 butanediol,
Aliphatic diol or aliphatic triol with a hydroxyl value of 300 or more added with one or more alkylene oxides (e.g., ethylene oxide, propylene oxide, butylene oxide, etc.) using glycerin, trimethylolpropane, or triethanolamine as an initiator. It is. Moreover, there is no problem even if two or more types are used in combination. Examples of aromatic polyisocyanates that can be used in the present invention include the following. trilene 2,4
Diisocyanate, tolylene 2,6 diisocyanate and mixtures thereof, diphenylmethane 4,4' diisocyanate, and polyisocyanate can be used in either purified or crude form.
Moreover, two or more types may be combined. The catalyst that can be used in the present invention is not particularly limited, and may be used alone or in combination with a urethane bond forming catalyst, a urea bond forming catalyst, or a Biuret bond forming catalyst. As a trimer production catalyst,
2,4,6 tris(dimethylaminomethyl)phenol, 0- and P-dimethylaminomethylphenol, NN′N″tris(dimethylaminopropyl)-sym-hexahydrotriazine, benzyltrimethylammonium methoxide, alkali of carboxylic acids Metal salts, alkali metal salts of weak acids other than carboxylic acids, inorganic bases, etc. can be used.Also, as the urethane bond forming catalyst, urea bond forming catalyst, and Biuret bond forming catalyst, all those generally used in the production of polyurethane foam can be used. These catalysts can be broadly classified into the third type.
Examples of tertiary amines include triethylamine, triethanolamine, diethanolamine, monoethanolamine, dimethylmonoethanolamine, triethylenediamine, tetramethylpropanediamine, and tetramethyl-1,3-butanediamine. , pentamethyldiethylenetriamine, and organometallic compounds such as dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dicaprylate, stannath octoate, and the like. Of course, one type or two or more types of these may be used. The amount of these catalysts to be used should be determined in consideration of reactivity. In the present invention, the blowing agents can be broadly classified into two types: inert low boiling point solvents and reactive blowing agents, but it is desirable to use the inert solvent alone or in combination with a small amount of the reactive blowing agent. As inert low-boiling solvents, salt fluorinated alkanes are commonly used; specific examples include methylene chloride, ethylene trichloride, trichloromonofluoromethane, dichlorodifluoromethane, dichloromonofluoromethane, dichlorotetrafluoroethane, and Bromomonofluoromethane and the like can be used, and water can be used as the reactive blowing agent. Any surfactant that is effective for producing polyurethane foam can be used in the present invention. For example, polyoxyalkylene-based materials such as polyoxyalkylene alkyl ether and polyoxyalkylene alkylamino ether, silicone-based materials such as organopolysiloxane and siloxane oxyalkylene copolymers, and esters such as funnel oil can be used.
The rigid foam according to the present invention is self-extinguishing according to ASTM D1692 without the use of flame retardants, although they may be used if necessary. For example, tricresyl phosphate, tris (β-chloroethyl) phosphate, tris (chloropropyl)
Phosphate, phosphoric acid esters such as O,O′diethyl-N,Nbis(2hydroxyethyl)aminomethylphosphonate, ammonium trioxide,
Alumina, metal oxides such as antimony oxychloride, chlorides, etc. can be used. In addition, if necessary, coloring agents such as pigments and dyes, inorganic fillers such as barium sulfate, calcium carbonate, calcium silicate, silica, calcium sulfate, calcium sulfite, and aluminum sulfite, and inorganic fibers such as rock wool, asbestos, and glass fiber. etc. can be used. When using these, it is convenient to knead part or all of the composition such as polyol in advance using a roll mill or the like. Any method may be used to mix and foam the raw materials of the present invention as long as the reaction mixture can be mixed uniformly. For example, it is convenient to use a foaming machine used for manufacturing polyurethane foam, epoxy foam, etc. Therefore, any foaming method such as injection foaming or spray foaming is possible. When the thickness of the hard foam layer is small or when it comes into contact with a metal plate, it is necessary to preheat the reaction mixture and the metal plate that will come into contact with the hard foam. The urethane-modified polyisocyanurate foam obtained according to the present invention has excellent heat resistance and flame resistance, and has improved foam brittleness and skin condition. Examples of the present invention will be described below, but the present invention is not limited to these examples. Examples 1 to 13 The reaction mixture shown in Table 1 was weighed into a polyethylene beaker No. 1, and stirred vigorously for 5 to 10 seconds at room temperature (20-25°C) with a cage mixer (rotation speed 3400 rpm). A urethane-modified isocyanurate foam was obtained by foaming in an open wooden box. Urethane-modified isocyanurate foams using aliphatic diols or aliphatic triols have lower
It had excellent heat resistance, flame resistance, and brittleness, and had no irregularities on the foam surface. Furthermore, since the viscosity of the polyol mixture component is low, metering, mixing and discharging can be carried out smoothly, and a normal urethane foaming machine or isocyanurate foaming machine can be used.
This difference is particularly noticeable in urethane-modified isocyanurate foams with high isocyanate equivalents. Comparative Examples 1 to 3 Urethane-modified isocyanurate foams were obtained using the reaction mixtures shown in Table 1 in the same manner as in Example 1. It was not excellent in heat resistance, brittleness, and surface unevenness. Crude MDI: A crude product of diphenylmethane 4,4' diisocyanate with an isocyanate content of 31%. Polyol A: the above general formula R: propylene group n ₃
~ _n8 : An aromatic amine polyol having a manufacturing number of 1 to 3, m: an integer of 0 to 4, and a hydroxyl value of 500. Polyol B: An aromatic diol with a hydroxyl value of 300, made by adding propylene oxide to bisphenol A. Polyol C: Aliphatic diol with a hydroxyl value of 560 made by adding ethylene oxide to ethylene glycol. Polyol D: Hydroxyl value 420 made by adding propylene oxide to glycerin
aliphatic triol. The foam testing method used in the present examples and comparative examples is as follows. a Flame resistance test (flame penetration test) Bureau of Mines Report of
According to the method of Investigation NO 6366 (1964),
A test piece with a thickness of 25 mm was used. b Brittleness test (fryability) Tested for 10 minutes according to ASTM-C-421-61.
The smaller the number, the more brittle (flyability)
indicates that the value is low. c. Heat resistance test (volume change rate at 150°C) A 100 x 100 x 50 mm foam was left in an oven at 150°C for 24 hours, and then the rate of change (%) in the volume of the test piece was measured. The smaller the number, the higher the heat resistance. 【table】

Claims (1)

[Claims] 1. When producing a urethane-modified polyisocyanurate foam from a polyol, an aromatic polyisocyanate, a blowing agent, a catalyst, and a surfactant, as a polyol, the general formula and/or [ _n1 to _n8 : number of 1 to 7, m: number of 0 to 4, R: alkylene group], and this aromatic amine polyol is 50% of the total amount of polyols. Contains at least % by weight and has a general formula [x ₁ , x ₂ : number of 1 to 2 R′ : alkylene group] For 100 parts by weight of a mixed polyol containing 50% by weight or less of the total polyol, a polyol having a hydroxyl value of 300 or more is used. A urethane-modified isocyanurate foam characterized in that an aliphatic diol or aliphatic triol is used in an amount of 5 to 25 parts by weight, and an aromatic polyisocyanate is used in an amount of 2 to 10 times the equivalent of the total amount of the active hydrogen compound containing the above-mentioned polyol. manufacturing method.