JPS6141928B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to the stabilization of amines used as catalysts in compositions containing halogenated polyols for the production of polyurethane foams. Polyurethane foams are generally made by reacting organic polyisocyanates with polyols in the presence of blowing agents and reaction catalysts. Although a variety of catalysts have been disclosed in the art to promote this type of reaction, the most widely and successfully used catalysts are aliphatic and cycloaliphatic amines and other catalysts such as stannous octoate. mixtures with selected metal salts. These desirable amine catalysts have active aspects that provide advantageous processing properties. Catalyst compositions for polyurethane foams have previously been disclosed in the art that include certain amine and acid salts. For example, US Pat. No. 3,372,130 to Chess et al. shows a catalyst consisting of a tertiary amine and phosphoric acid used to control the rate of foam rise. U.S. Pat. No. 3,706,687 to Rudgki describes a foam catalyst consisting of a mixture of an aliphatic tertiary amine and a tertiary amine salt of an alkylaryl sulfonic acid. No. 3,728,291 to Carroll et al. uses triethylene diamine diformate salt in combination with hydroxylpropylimidazole as a catalyst composition for polyurethane foams. However, none of these patents are directed to stabilized amine-catalyzed polyurethane foam compositions containing halogenated polyols. Polyurethanes obtained from halogenated polyols exhibit varying degrees of flame resistance; and in view of the increasing demand for flame-retardant polyurethane foams, a number of halogenated polyol compositions have been developed for use in the polyurethane industry. . Examples of these are polyether polyols containing two or more halogens substituted on aliphatic carbon atoms within the polyol molecule. See, eg, US Patent Nos. 3,402,169 and 3,726,855. It has recently been discovered that halogenated polyols, such as those mentioned above, have a deleterious effect on amine catalytic stability. Therefore, when contacted with such a polyol, the amine loses its catalytic activity, and the loss of activity becomes more pronounced the longer the contact. Although the chemical nature of this phenomenon is still not fully understood,
This is particularly evident in applications where the amine catalyst is precompounded with the halogenated polyol and the blend is then stored or transported for use in the production of polyurethane foams. In accordance with the present invention, it has now been discovered that amine-catalyzed halogenated polyol compositions can be stabilized against catalyst degradation during storage by blocking the amine catalyst with an acid. Accordingly, in accordance with the present invention there is provided an improved catalytic polyol composition comprising a halogenated polyol and an acid-blocked amine catalyst that can be advantageously used in the production of polyurethane foams. As used herein in the specification and claims, the term "halogenated polyol" is intended to include any polyol containing at least one halogen atom substituted on an aliphatic carbon atom in the polyol molecule. In this case, halogen refers to chlorine, bromine, or a mixture thereof. These polyols usually have 2-8 hydroxy groups and include polyether polyols, polyesterols and mixtures thereof. However, polyether polyols are preferred, including mixtures of halogenated and halogen-free polyether polyols. Polyether polyols include halogenated oxyalkylated polyols. These things can be made by methods well known in the art,
Therein, polyhydroxy compounds are condensed with halogenated alkylene oxides or with mixtures of halogenated and non-halogenated alkylene oxides using a random or stepwise addition method, optionally in the presence of an oxyalkylation catalyst. US Pat. No. 3,402,169 issued September 17, 1969 to DR Jackson provides a detailed description of this process.
The complete disclosure of this Jackson patent is incorporated herein by reference. Any polyhydroxy compound can be used in the preparation of halogenated polyether polyols, including mixtures of such compounds and their alkylene oxide condensates;
- Contains 8 hydroxy groups and is suitable for reacting alkylene oxides to form polyethers. Therefore, a wide range of polyhydroxy compounds is expected for the preparation of halogenated polyether polyols. To illustrate, polyhydroxy compounds include ethylene glycol, propylene glycol, isobutylene glycol, 2,3-butanediol, 1,4-dihydroxy-2-butane,
1,4-dihydroxycyclohexane, 2-butyne-1,4-diol, 1,12-dihydroxyoctadecane, glycerin, trimethylolpropane, sorbitol, mannitol, inositol, erythritol, pentaerythritol,
Sucrose, dextrose, methyl glucoside, 1,4-dimethylolbenzene, glycerin, monochlorohydrin, diglycerol, methyl ether of glycerin, mixtures thereof, and combinations thereof with alkylene oxides, such as ethylene oxide, propylene oxide and butylene oxide. Contains condensates of Polyhydroxy compounds are also a preferred group of carbohydrate-based substances, especially dextrose-
and sucrose-based substances. As used herein in the specification and claims, the term "dextrose-based material" means one of the following: mixtures of dextrose and water, oxyalkylated mixtures of dextrose and water, dextrose and aliphatic Mixtures with polyhydric alcohols, oxyalkylated mixtures of dextrose and aliphatic polyhydric alcohols, mixtures of dextrose, water and aliphatic polyhydric alcohols, or oxyalkylated mixtures of dextrose, water and aliphatic polyhydric alcohols. Dextrose can be anhydrous such as d-glucose or ∝-d-glucose monohydrate. Similarly, the term "sucrose-based material" means one of the following: mixtures of sucrose and water, oxyalkylated mixtures of sucrose and water, mixtures of sucrose and aliphatic polyhydric alcohols, sucrose and fats. Oxyalkylated mixtures of group polyhydric alcohols, mixtures of sucrose, water and aliphatic polyhydric alcohols, or oxyalkylated mixtures of sucrose, water and aliphatic polyhydric alcohols. Examples of aliphatic polyhydric alcohols that can be used to prepare dextrose- and sucrose-based materials include aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, glycerol, trimethylolpropane, mixtures thereof, and the like. Contains diols and triols.
Dextrol-based materials, particularly mixtures of dextrose and aliphatic diols or triols, are particularly desirable for the preparation of halogenated polyether polyols for use in the compositions of this invention. In the preparation of the dextrose- and sucrose-based materials mentioned above, water and/or
Or any suitable molar ratio of aliphatic polyhydric alcohol to dextrose or sucrose can be used. However, generally for each mole of dextrose or sucrose, at least about
It is desirable to use 0.7 moles, and more preferably about 0.9-4 moles, of each water and/or aliphatic polyhydric alcohol. A more detailed description of the preparation of dextrose- and sucrose-based materials is given in US Pat. No. 3,741,921, issued June 26, 1973, to M. Rapkin. The entire disclosure of this patent is incorporated herein by reference. Any alkylene oxide, or mixtures thereof, can be used to prepare the halogenated polyether polyols, having one or more halogen atoms substituted with aliphatic carbon atoms, where the halogens include chlorine, bromine, or a mixture thereof;
The alkylene oxide is capable of reacting with a polyhydroxy compound to form a polyether. Halogen-substituted alkylene oxides usually contain an epoxide ring and have 2-4 carbon atoms.
Particularly preferred are vicinal epoxides, especially those having 3-4 carbon atoms. Typical examples of these are epichlorohydrin; 3,3-dichloro-1,2-epoxypropane; 3,3-dibromo-1,2-epoxypropane; 3,3,3-trichloro-1,2-epoxypropane; 4,
4-tri-trichloro-1,2-epoxybutane; 4,4,4-tribromo-1,2-epoxybutane; 4,4,4,3,3-pentachloro-
1,2-epoxybutane; 1,1,1,4,4-
pentachloro-2,3-epoxybutane; and mixtures thereof. Preferred such halogenated alkylene oxides are those having three halogens in the molecule, such as 4,4,4-trichloro-1,2-epoxybutane, where the halogen is chlorine. Any oxyalkylation catalyst suitable for promoting the reaction of the polyhydroxy compound and the halogenated alkylene oxide can be used. This includes basic catalysts such as sodium hydroxide, and acidic catalysts such as boron trifluoride and their etherate derivatives. The latter catalysts are preferably used in the preparation of polyether polyols, which are derived from hydrocarbon-based polyhydroxy compounds. The relative proportions of alkylene oxide, or mixture of alkylene oxides, used will depend on the number of hydroxyls desired in the polyether product, as is well known in the art. In preferred embodiments of the invention, about 100-800, more preferably about 200
Sufficient amount of halogenated alkylene oxide or mixture thereof is used to yield a halogenated polyether polyol having a hydroxyl number of -700, and even more preferably 250-650. and halogenated in such a proportion that the halogen content in the polyether polyol is not less than about 15%, more preferably about 20-80%, and still more preferably about 25-60%, by weight. Preferably, alkylene oxides are used. The amine catalyst stabilized according to the present invention can be any amine that acts as a promoter for the reaction of an organic polyisocyanate and a polyol to form a polyurethane. However, the preferred amine catalysts are the customary alkyl tertiary amines. As used herein in the specification and claims.
The term "alkyl tertiary amine" is intended to include any such amines and mixtures thereof, including mono- and di-amines. Examples are aliphatic tertiary mono- and di-amines, cycloaliphatic tertiary amines and tertiary aminoalkanols. All of these tertiary amines usually contain 3-10, and preferably 4-8 carbon atoms. Examples of aliphatic tertiary amines include trialkyl monoamines such as trimethylamine and triethylamine, trialkylene diamines such as triethylenediamine, and N,N,N',N'-
N,N, such as tetramethylbutanediamine
It is N',N'-tetraalkyl alkylene diamine. Alicyclic tertiary amines are exemplified by dialkylcyclohexylamines such as dimethylcyclohexylamine and diethylcyclohexylamine; and tertiary aminoalkanols are exemplified by dialkylcyclohexylamines such as dimethylethanolamine and dimethylpropanolamine, methyldiethanolamine and methyl Illustrated by alkyl dialkanolamines such as dipropanolamine, and trialkanolamines such as trimethanolamine, triethanolamine, diethanolpropanolamine, and tripropanolamine. The most preferred tertiary amine catalysts for use in the compositions of the present invention are triethylenediamine, dimethylcyclohexylamine, N,N,N',N'-tetramethylbutanediamine, triethanolamine, dimethylethanolamine, and the like. It is a mixture. Particularly preferred is a mixture of dimethylcyclohexylamine and dimethylethanolamine. Any suitable proportion of amine effective to catalyze the reaction of a halogenated polyol and an organic isocyanate can be used in the compositions of the present invention. Therefore, for every 100 parts by weight of halogenated polyol, approximately
Catalyst quantitative proportions such as 0.02-5, preferably about 0.05-3, and more preferably about 0.075-2 parts by weight are commonly used. According to the present invention, a blocking acid is used to stabilize the amine catalyst, which gradually deteriorates due to interaction with the halogenated polyol. A suitable acid capable of forming stable salts with amine catalysts is formic acid. Amine catalysts blocked with formic acid are more stable than amine catalysts blocked with other acids, and their activity decreases less even after prolonged contact with halogenated polyols at relatively high temperatures. Amines are blocked by reacting with acids to form salts. As shown in Equation A below, using the illustratively preferred formic acid blocking agent and dimethylcyclohexylamine catalyst, the tertiary amine reacts with the acid to form a salt, dimethylaminohexyl formate, thereby Blocks the amine from reacting or degrading the halogenated polyol. The blocking reaction is accomplished by mixing the amine catalyst and acid prior to incorporation into the polyurethane foam premix. However, desirably blocking is conveniently accomplished "in situ" by incorporating an acid blocking agent into the halogenated polyol premix composition when the premix is formulated, prior to or simultaneously with the addition of the amine catalyst. I can do it. Advantageously, ambient temperature conditions can be used, but block reactions are generally performed over a wide temperature range, e.g., from about -20° to about 100°C.
This can be done at To effectively block the amine catalyst, at least about a stoichiometric or greater amount of acid is used relative to the amount of amine catalyst. Therefore, from about 1 mole to about 2 moles per mole of amine catalyst.
Molar acids are generally used, with the preferred ratio being about 1:1 to about 1.5:1. The catalyzed halogenated polyol compositions described herein are utilized in the preparation of polyurethane foams according to the method of the present invention. For this purpose, it is reacted with organic polyisocyanates in the presence of blowing agents. Conventional techniques such as one-shot or prepolymer techniques are used to carry out the form-forming reaction. Any combination of polyols, organic isocyanates, blowing agents, catalysts, plasticizers, and other reactants capable of forming a polyurethane foam reaction mixture can be used. The organic polyisocyanates used in the polyurethane foams of the present invention include 2,4- and 2,6-
toluene diisocyanate, ethylene diisocyanate, propylene diisocyanate, methylene bis-(4-phenyl isocyanate), such as 80:20 or 65:35 isomer mixtures in isomeric form;
3,3'-bitolene-4,4-diisocyanate, hexamethylene diisocyanate, naphthalene 1,5-diisocyanate, polyphenylene,
Included are polymeric isocyanates such as polymethylene isocyanate, and the like, and mixtures thereof. The amount of isocyanate used in this process will generally be sufficient to provide at least about 0.7 NCO groups for hydroxy groups in the reaction system, including the polyol and any additional materials and/or blowing agents present. Should. In practice, polyisocyanates are generally used in proportions to provide no more than about 1.25 NCO groups for each hydroxy group. The ratio of 100 times the NCO to OH groups in the reaction system is called the "index." Any suitable blowing agent or blowing agent mixture can be used. These include inorganic blowing agents such as water;
and halogenated hydrocarbons, and organic blowing agents containing up to 7 carbon atoms such as low molecular weight alkanes, alkenes, and ethers. Examples of organic blowing agents include monofluorotrichloromelone, dichlorofluoromethane, dichlorodifluoromethane, 1,1,2-trichloro-1,2,2
-Trifluoroethane, memelene chloride, chloroform, carbon tetrachloride, methane, ethane, ethylene,
Includes propylene, hexane, ethyl ether, diisopropyl ether, mixtures thereof and the like. Water and low molecular weight polyhalogenated alkanes such as monofluorotrichloromethane and dichlorodifluoromethane are preferred. The amount of blowing agent can vary within a wide range. Generally, however, the halogenated hydrocarbon will be used in an amount ranging from about 1 to about 75 parts by weight per 100 parts by weight of total polyol in the form-forming reaction system; and water will generally be used in an amount ranging from about 0.1 part by weight per 100 parts by weight of total polyol.
or about 10 parts by weight. In preparing the polyurethane foams of the present invention, it is desirable to use small amounts of conventional surfactants in order to further improve the cellular structure of the polyurethane foams. Typical of such surfactants are silicone oils and soaps and siloxane-oxyalkylene block copolymers. U.S. Patent No. 283448 and TH Ferringo's "Hard Plastic Foam"
(New York: Reinhold Publishing Company, 1963)
pp. 34-42, et al. disclose a variety of surfactants useful for this purpose. A preferred class of surfactants are polysiloxanes such as those available under the trademark "Niax L-5303." Generally up to 2 parts by weight of surfactant are used per 100 parts by weight of total polyol. It is often desirable to incorporate additional polyol into the foam-forming reaction mixture to minimize surface friability of the resulting polyurethane foam. These chemicals are understood to accomplish this reduction in friability by promoting hardening and helping to reduce the viscosity of the foam reaction mass. Various polyols useful in this additive role and their methods of use are known in the art and are described in U.S. Pat. No. 3,928,257 to Fuzesi et al. An example is given below. The entire disclosures of these patents are incorporated herein by reference. Illustratively, additional polyols include selected groups of ethoxylated polyether polyols. Any suitable proportion of additional polyol effective to reduce the friability of the foam without interfering with or adversely altering the properties of the resulting foam can be used. Proportions ranging from about 5 to about 35, preferably from about 8 to about 30 parts by weight per 100 parts by weight of the primary polyol reactant are commonly used. The required proportions of additional polyol can be conveniently combined with the amine polyol reactant or can be added separately to the foam-forming reaction mixture. If desired, various other additives such as fillers, dyes, plasticizers, deodorants, and antioxidants can also be incorporated into the polyurethane foam-forming reaction mixture. The invention disclosed herein provides an easy and simple route to minimizing catalyst deactivation problems resulting from contact with halogenated polyols. In this way, a halogenated polyol composition is created for use in the production of flame retardant polyurethane foams containing amine catalysts that do not undergo substantial deterioration during storage or transportation. Such compositions are particularly useful for applications such as in-situ polyurethane foam production, where the foam-forming components are supplied from two containers, one of which contains the organic isocyanate alone or the blowing agent. and another vessel containing all of the other reactants, such as polyol with amine catalyst, all or part of the blowing agent, surfactant and additional polyol. Typical foaming equipment used to carry out in situ polyurethane foam generation processes is described in detail in US Pat. Nos. 3,769,232 and 3,541,021, the disclosures of both of which are incorporated herein by reference. The following examples are given to illustrate the invention. All parts and percentages in these examples are by weight unless otherwise indicated. EXAMPLE A series of amine-catalyzed halogenated polyol compositions were prepared by adding blocked and unblocked amine catalysts to halogenated polyols.
PH, ionic c ⁻ and available N ⁺ were analyzed before and after time aging. The decrease in pH over time indicates the dehydrohalogenation effect of the amine catalyst on the halogenated polyol. The change in ionic ^C- present in the composition after aging (measured by titration) is due to the C extracted from the halogenated polyol to form a salt with the amine groups of the catalyst.
Specify the amount of ^- . The available N ⁺ consumed is a further explanation of the deactivation reaction of the halogenated polyol with the amine catalyst. These analytical results, summarized in Section 1 and Table 1, demonstrate that by blocking the amine catalyst with acid in accordance with the present invention, the amine during the blowing reaction due to deactivation due to storage, pre-reaction with halogenated polyols, etc. It is clearly shown that a significant factor in the loss of reactivity of the catalyst can be effectively minimized. In the processing experiments shown in the table, the components of the sets and sets in the indicated proportions were mixed together and foamed into square cardboard boxes. A stopwatch was used to measure processing times - "cream time", "gel time", "tack-free time", and "rise time"; time measurements were taken from the moment the mixture was placed in the cardboard box. . "Cream time" is the elapsed time up to the point at which foaming begins, during which time the mixture transforms from a liquid to a cream or emulsion. "Gel time" is the elapsed time until the resulting foam becomes self-supporting as evidenced by the resistance of the foam to being penetrated with a blunt instrument. The "tack-free time" is the minimum amount of time that elapses after which the foam is no longer tacky. "Rise time" is the time elapsed until the foaming reaction or foam expansion is complete.

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Claims (1)

Claims: 1. A catalytically stable polyol composition for use in preparing polyurethane foams comprising a halogenated polyol and a formic acid blocked alkyl tertiary amine catalyst. 2 Claims characterized in that the alkyl tertiary amine is at least one compound selected from aliphatic tertiary mono- and di-amines, alicyclic tertiary amines, and tertiary amino alkanols. 1st
composition of the term. 3. A patent characterized in that the halogenated polyol is a product of about 250 to 650 hydroxyls formed by condensing a polyhydroxy compound with a halogenated alkylene oxide containing 3 to 4 carbon atoms and at least two halogens. A composition according to claim 1.