GB2034726A - Polyester Polyol Compositions - Google Patents

Abstract

Polyester polyol liquid compositions comprising: (a) a polyester polyol having a hydroxyl number of 50-500, an acid number of less than 2 and a halogen content of 17-60% by weight, said polyester polyol being the reaction product of an acid component comprising 50-100% by weight of a halogenated aromatic or cycloaliphatic polycarboxylic acid and 0-50% by weight of a halogen-free aromatic or cycloaliphatic polycarboxylic acid and an alcohol component comprising a dihydric alcohol and optionally a polyhydric alcohol having at least three hydroxyl groups, and (b) an organic phosphorus compound in an amount of from 5 to 50% by weight based on the weight of the polyol composition. The compositions are useful in the preparation of fire-resistant polyurethanes.

Description

SPECIFICATION Polyester Polyol Compositions This invention relates to polyester polyol compositions which are of value in the manufacture of fire-resistant polyurethanes.

It is well known to manufacture foamed or unfoamed polyurethanes by reacting polyester polyols with organic polyisocyanates in the presence of appropriate auxiliary agents It is also known to employ halogenated polyester polyols in this reaction in order to improve the fire resistance of the polyurethanes. The halogenated polyesters, which are usually made by reacting a polyhydric alcohol with a halogen-containing polycarboxylic acid, have higher viscosities than the conventional halogen-free polyesters and can be difficult to use. The polyurethane manufacturer can thus be in the position of having to choose between a polyester of acceptable viscosity which provides insufficient fire resistance for some purposes and a polyester having acceptable fireretardant properties but unsatisfactory handling characteristics.

The present invention provides polyester polyol compositions which minimise the aforementioned difficulties by providing a high level of fire retardance whilst at the same time being of acceptable viscosity.

Thus, according to the invention, there are provided polyester polyol liquid compositions comprising: (a) a polyester polyol having a hydroxyl number of 50-500, an acid number of less than 2 and a halogen content of 1760% by weight, said polyester polyol being the reaction product of an acid component comprising 50100% by weight of a halogenated aromatic or cycloaliphatic polycarboxylic acid and 0-50% by weight of a halogen-free aromatic or cycloaliphatic polycarboxylic acid and an alcohol component comprising a dihydric alcohol and optionally a polyhydric alcohol having at least three hydroxyl groups, and (b) an organic phosphorus compound in an amount of from 5 to 50% by weight based on the weight of the polyol composition.

The acid component used in making the polyester polyol contains at least 50% by weight of a halogenated aromatic or cycloaliphatic polycarboxylic acid or a mixture of such acids. It may also contain up to 50% by weight of a halogen-free aromatic or cycloaliphatic polycarboxylic acid or a mixture of such acids. The preferred polycarboxylic acids, halogenated or halogen-free, are dicarboxylic acids. In practice and where appropriate, the acids may be used in the form of their anhydrides.

Suitable halogenated aromatic or cycloaliphatic polycarboxylic acids include especially those containing chlorine or bromine atoms. Examples of suitable acids include tetrachlorophthalic acid, tetrabromophthalic acid and 1, 4, 5, 6, 7, 7-hexachlorobicyclo-(2.2. 1)-5- heptene-2,-3-dicarboxylic acid, the latter being commonly known as chlorendic or HET acid. All of these acids may conveniently be used in the form of their anhydrides.

Halogen-free aromatic and cycloaliphatic polycarboxylic acids which may be used in making the polyesters include tetrahydrophthalic, hexahydrophthalic, trimesic and trimellitic acids and especially phthalic acid. These acids may conveniently be used in the form of their anhydrides.

The alcohol component used in making the polyester polyol contains a dihydric alcohol.

Example of suitable dihydric alcohol include ethylene glycol, 1,2-propylene glycol, diethylene glycol, 1 ,4-butanediol, dibromoneopentylene glycol and the bishydroxyethyl ether of tetrabromo bisphenol A. The alcohol component may also include a polyhydric alcohol having more than two hydroxyl groups per molecule, for example glycerol, trimethylolpropane or pentaerythritol.

In making the polyester polyols, the acid component and the alcohol component may be reacted together under completely conventional conditions. Thus, they may be reacted together, optionally in the presence of an esterification catalyst in an inert atmosphere at normal or reduced pressures and at an elevated temperature, the water of condensation being removed as it is formed. Polyesters having any desired hydroxyl number within the range 50500 may be obtained in known manner by employing the appropriate excess of alcohol component relative to acid component, the reaction being continued until the desired acid number has been attained. The desired halogen content is achieved by using a halogenated aromatic or cycloaliphatic polycarboxylic acid which itself has an appropriate halogen content and if necessary using a mixture of halogenated and halogen-free acids.Account must also be taken of any halogenated polyhydric alcohols used in making the polyesters. By varying the reactants, it is also possible to vary the hydroxyl functionality of the polyester polyols. Thus, when the reaction mixture consists exclusively of dihydric alcohols and dicarboxylic acids, the product is a linear polyester polyol having two hydroxyl groups per molecule. When a higher functionality reactant such as glycerol is included, the product is a branched polyester having, on average, more than two hydroxyl groups per molecule.

The organic phosphorus compound present in the polyester polyol composition of the invention must be capable of forming a composition that is liquid at normal ambient temperatures when mixed with the polyester polyol in the stated proportions. Suitable phosphorus compounds are themselves liquids at normal ambient temperatures or can be liquefied by slight heating.

Examples of suitable organic phosphorus compounds include triaryl and trialkyl phosphates which may carry substituents in the aryl and alkyl groups. Examples of specific compounds which may be used include triphenyl phosphate, tricresyl phosphate, trixylyl phosphate, tri(isopropylated phenyl) phosphate, tris chloroethyl phosphate, tris chloropropyl phosphate, triethyl phosphate and the compounds available under the names Vircol 611 and Vircol 80.

The polyester and the organic phosphorus compound may be mixed together in any convenient manner. It is often expedient to add the phosphorus compound at the end of the polyester manufacturing process whilst the polyester is still warm so as to facilitate mixing.

The phosphorus compound is used in an amount to give a liquid composition having the desired viscosity characteristics.

The polyester polyol compositions of the invention may be reacted with organic polyisocyanates, such as tolylene diisocyanate and diphenylmethane diisocyanate, to form polyurethanes having a high degree of fire resistance as measured by the well known standard tests. The polyurethanes may be foamed or unfoamed and may be prepared using any of the known preparative methods.

For the preparation of polyurethanes, the polyester polyol is selected in known manner as to hydroxyl number and functionality to form the desired type of product, for example foamed or unfoamed, flexible or rigid.

The polyurethane forming reaction mixture may also contain other conventional ingredients of such reaction mixture and if desired the composition of the reaction mixture may be such that the polyurethane product has partially, or even predominantly, a polyisocyanurate or polyurea structure.

The invention is illustrated but not limited by the following Examples in which all parts and percentages are by weight.

Example 1 1,2-propylene glycol (22.2 parts), glycerol (7 parts), anhydrous sodium acetate (0.85 parts), tetra-n-butyl ortho-titanate (0.013 parts) and tetrabromophthalic anhydride (125 parts) were charged in that order to a reactor fitted with a distillation column. The reactants were agitated at 35-40CC for 1 5-30 minutes with a slow nitrogen stream passing through the mixture. The reactants were then heated to 1 700C at which point water commenced to distil via the column.

The reactants were heated further to 1 80- 1 850C consistent with the column head temperature not exceeding 1 000C. Reaction temperature was maintained at 180-1 850C with a continuous nitrogen stream until the acid value of the condensing mixture fell to below 2 mg KOH/g.

The polyester, having a hydroxyl value of 73.1 mg KOH/g and a bromine content of 57.5%, was cooled to 1 400C and tris(2chloropropyl)phosphate (117 parts) preheated to 45--500C, was added over about 1 5-20 minutes. The solution was stirred for further 30 minutes at 50-600C and filtered.

The product, an amber coloured clear viscous liquid, had a hydroxyl value of 41.08 mg KOHfg and an acid value of 0.96 mg KOH/g.

Example 2 1,2-propylene glycol (490.9 parts), glycerol (243.3 parts) anhydroussodium acetate (13.8 parts), tetra-n-butyl ortho-titanate (0.29 parts) and tetrabromophthalic anhydride (2758.7 parts) were charged to a reactor with a slow stream of nitrogen passing through the reactants.

The temperature inside the reactor was raised to 1 700C at which point water commenced to distil from the column. The temperature was further raised to 1 800C consistent with the column head temperature not exceeding 1000C.

The temperature of the reactants was then held at 180-1 850C until the acid value fell below 2.0 mg KOH/g. The resulting polyester, having a hydroxyl value of 115.3 mg KOH/g and a bromine content of 55.9%, was cooled to 1 400C.

A mixture of Reofos 50 (880.8 parts) (a tris isopropylated phenyl phosphate) and molten triphenyl phosphate (1321.2 parts) held at 55 OC was added to the polyester over about 10 minutes and the resulting solution agitated for a further 30 minute period before cooling and filtering.

The product an amber coloured viscous liquid had a hydroxyl value of 70 mg KOH/g and an acid value of 0.3 mg KOH/g.

Example 3 1,2-propylene glycol (763.9 parts), glycerol (243.3 parts) tetra-n-butyl ortho-titanate (0.3 parts) and tetrachlorophthalic anhydride (2646.8 parts) were heated with agitation and a current of nitrogen passed through the reactants. At 1 500C water commenced to distil off via the column.

Reaction temperature was slowly raised to 1 800C whilst maintaining the column head temperature at a maximum of 1000C. The temperature of the reacting mixture was then held at 180-1 850C and finaliy at about 2000C until the acid value of the resulting polyester fell below 2.9 mg KOH/g.

The polyester (3467 parts) having a hydroxyl value of 94.0 mg KOH/g and a chlorine content of 37.8% was cooled to about 1 400C and diluted with tris(2-chloropropyl)phosphate (2311 parts) preheated to about 450C. The product, an amber coloured viscous liquid, had hydroxyl value of 56.4 mg KOH/g and an acid value of 1.58 mg KOH/g.

Claims (3)

Claims

1. A polyester polyol liquid composition comprising: (a) a polyester polyol having a hydroxyl number of 50-500, an acid number of less than 2 and a halogen content of 1760% by weight, said polyester polyol being the reaction product of an acid component comprising 50100% by weight of a halogenated aromatic or cycloaliphatic polycarboxylic acid and 0-50% by weight of a halogen-free aromatic or cycloaliphatic polycarboxylic acid and an alcohol component comprising a dihydric alcohol and optionally a polyhydric alcohol having at least three hydroxyl groups, and (b) an organic phosphorus compound in an amount of from 5 to 50% by weight based on the weight of the polyol composition.

2. A composition as claimed in claim 1 substantially as hereinbefore described with reference to any one of the foregoing Examples.

3. Polyurethanes whenever prepared by reacting an organic polyisocyanate with a composition as claimed in claim 1 or claim 2.