DE2321884A1 - PROCESS FOR THE PRODUCTION OF POLYURETHANE FOAM - Google Patents

Description

The invention relates to a "method for producing Polyurethane foams and especially rigid polyurethane foams. The invention also relates to a process for the production of polyurethane foams for the production of such polyurethane foams useful polyols.

It is known to produce polyurethane foams by that two prepared packs (a) and (b) are mixed under foam-forming conditions, the Package (a) comprises a polyether polyol prepared with a tertiary amine catalyst and a silicone oil and an organic polyisocyanate is present in pack (b), and either pack (a) has a polymerization catalyst contains or such a catalyst that formed by mixing the packing (a) with the packing (b) Reaction mixture is added.

The polyurethane foams produced using this known process may have a poor one

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Cell structure, especially if package (a) comes after some Weeks or months of storage used and / or several hours at a temperature above ambient, e.g. held at 35-70 ° C before mixing with package (b). The poor cell structure is partially expressed from a low content of closed cells in the foam produced, e.g. below 80% by volume can lie.

One of the reasons why sometimes the package (a) is kept at temperatures above ambient for several hours is because certain polyether polyols are viscous materials and therefore usually at such temperatures mixed with the silicone oil (and various other components) to facilitate the mixing process. There in addition, the package (a) is easier to handle at such a temperature, it is thereby held and transported.

Surprisingly, it has now been found that polyurethane foams can be used can produce which have a better cell structure than that previously described above Process produced when one of the polyether polyol component of the pack (a) adds an acid before the pack (a) is stored for several weeks or months and / or is held for several hours at a temperature above ambient temperature.

Purely theoretically and without any limiting effect on the invention, it can be assumed that the reason for the better cell structure of those produced according to the invention Polyurethane foams are that in the known process, the polyatherpolyol component still residues of the contains tertiary amines used as a catalyst,

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apparently in the form of quaternary ammonium derivatives of the amine and in the form of free tertiary amine, and that these strongly basic compounds destroy the silicon oil component of package (a), which is likely due to longer storage times and / or temperatures above ambient temperature is promoted. This theory is supported by the fact that silicone oils are known to improve the cell structure of polyurethane foams. One reason that the neutralization of the polyether polyol so far has not yet been proposed, it is likely that tertiary amines cause the reaction between package (a) and Catalyze pack (b) and that it therefore appeared advantageous to have the unneutralized tertiary amine in the pack (a) leave behind.

The invention therefore relates to a method for production of polyurethane foams, which consists in making two packages (a) and (b) under foam-forming conditions mixed, wherein package (a) comprises a polyether polyol produced by catalysis with a tertiary amine, to which an acid and a silicone oil are added and wherein an organic polyisocyanate is present in package (b) and furthermore packing (a) contains a polymerization catalyst or a polymerization catalyst by mixing reaction mixture formed by packing (a) with packing (b) is added.

Polyether polyols suitable for use in package (a) include those having from 2 to 8 hydroxyl groups. Such Polyols can be produced by reacting one or more polyols, such as ethylene glycol, propylene glycol, Diethanolamine, diphenylolpropane, glycerin, trimethylolpropane, pentaerythritol, mannitol, glucose, sucrose or sorbitol with one or more alkylene oxides, such as ethylene and / or propylene

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oxide. The method according to the invention is particularly advantageous when the viscosity of the polyether polyol in question is so high that it is at temperatures above ambient temperature must be handled. Such viscous polyether polyols are usually made by reacting alkylene oxides with polyols having at least four hydroxyl groups. A particularly preferred polyether polyol is made by reacting sucrose with a mixture of ethylene and / or propylene oxide, wherein the preferred weight ratio of propylene oxide to ethylene oxide is 70:30 to 95: 5 lies.

Examples of tertiary amines used in the manufacture of the polyether polyols contained in package (a) can serve as a catalyst are: trimethylamine, triethylamine, Tripropylamine and N, N-dimethyl-2-aminoethanol, including trimethylamine and N, F-dimethyl-2-aminoethanol are preferred. Appropriate proportions for that serving as a catalyst tertiary amines are 0.1 to 3 weight percent based on weight of the polyol used to react with the alkylene oxide.

Examples of acids which are added to the polyether polyol according to the invention are inorganic acids such as hydrochloric or phosphoric acid and organic acids such as formic or acetic acid, formic acid and phosphoric acid being preferred. Preferably the acid is added to the polyether polyol before it is mixed with the silicone oil. The amount of acid added is usually more than 0%, for example at least 20 % and preferably at least 80 % of the stoichiometric equivalent for the amine catalyst used in the preparation of the polyether polyol. After adding acid in an amount of 100% of the stoichiometric equivalent, the pH value of the polyether

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polyols, determined in 25% aqueous solution, of about 11 on about? · So one can assume that the acid is the free tertiary amine component of the polyol, as well as about has neutralized formed quaternary ammonium compounds.

Examples of silicone oils that can be used in package (a) are silicone block copolymers, e.g. siloxaneoxyalkylene polymers, such as the commercial products DC 193 (manufacturer Dow Corning) or SF 1066 (manufacturer General Electric). Generally speaking, such silicone oils are characterized in that they contain at least one silicone oxygen -Binding is in place. The package (a) preferably contains 0.5 to 3.0 parts by weight of silicone oil, calculated on 100 parts by weight of polyether polyol.

The pack (a) can also contain a polyether polyol or several other polyols, e.g., polyalkoxylated diols and / or Triplet included. Preferably the additional polyols comprise at least one polyalkoxylated glycerin prepared by reacting glycerol with one or more alkylene oxides, such as propylene oxide, in the presence of a catalyst, which is not a tertiary amine. Expediently, the pack (a) contains 30 to 50 parts by weight of one or several alkoxylated glycerols, calculated on 100 parts by weight of polyether polyol. The polyalkoxylated glycerin can be a mixture of polyols, for example it can consist of a propoxylated glycerine which is produced by Acid catalysis, e.g. by catalysis with boron trifluoride, and a propoxylated one produced by catalysis with potassium hydroxide Glycerin. Such additional polyols are, generally speaking, either through a base or through neutralizes an acid.

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Organic polyisocyanates suitable for use in package (b) include monoaryl and polyaryl polyisocyanates, such as polyaryl polyalkylene polyisocyanates. Examples of monoaryl polyisocyanates are tolylene-2,4-diisocyanate and tolylene-2,6-diisocyanate and mixtures thereof, for example mixtures in a ratio of 80:20 or 65:35 parts by weight, m-phenylene diisocyanate and p-phenylene diisocyanate. Examples of Polyarylpolyisocyanate are naphthalene-1,5-diisocyanate ₄ diphenylmethyl-4,4'-diisocyanate, 3-methyldiphenylmethane-4,4-diisocyanate and ^t diphenyl-4,4'-diisocyanate.

A particularly suitable polyaryl polyisocyanate is crude Diphenylmethane diisocyanate, produced by phosgenation of crude diphenylmethanediamines, which can be obtained by reacting aromatic amines such as aniline, _o-chloroaniline and jo-toluidine, with formaldehyde and hydrochloric acid. If aniline is used as the aromatic amine, the product is a mixture of diphenyl-4,4'-diisocyanate, Diphenyl 2,4'-diisocyanate and related polyisocyanates from higher molecular weight and functionality, such as the tri- and tetraisocyanates.

The proportion of such components in the mixture will vary with the amount of used to make the crude diphenylmethane polyamines amount of formaldehyde and aniline used. Suitable weight ratios of aniline to formaldehyde are included 4: 1 to 4: 1.5.

Suitable crude diphenylmethane diisocyanates contain about 30 to 90, preferably 40 to 65 wt .-% polyisocyanate with a functionality of more than 2. The difunctional material contains a substantial proportion of diphenylmethane-4,4'-diisocyanate. The proportions of the above components can

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can also be varied by starting from the raw, serving as a starting material diphenylmethanediamine somewhat Diphenyl - ^ - ^ 'diamine or from the crude diphenylmethane diisocyanate some diphenylmethane - ^ - jV-diisocyanate removed.

Preferably, the amount of organic polyisocyanate in pack (b) is adjusted so that for each in pack (a) Equivalents of hydroxyl groups present 0.9 "to 1.2 equivalents are present on isocyanate groups.

The polymerization catalyst that controls the reaction between the polyols in package (a) and the organic polyisocyanates catalyzed in pack (b) can be any "any catalyst customary for the polymerization of polyurethane. It is preferred to use a tertiary amine such as triethylenediamine and / or dimethylcyclohexylamine. With some amine catalysts, especially with triethylenediamine, it is advantageous to neutralize the catalyst with an acid, before adding it to package (a). The amount of catalyst can vary within wide limits and is e.g. 0.5 to 5% by weight, calculated on the total weight Polyol in package (a).

The packs (a) and (b) are mixed under foam-forming conditions, e.g. by either placing in pack (a) incorporating water and / or by adding a volatile hydrocarbon, e.g. trichlorofluoromethane, in pack (a) or in pack (b), incorporated. Such conditions for foam formation are known to the person skilled in the art.

The inventive method can be used for Manufacture of shaped pieces, raw panels for laminates, but is particularly useful for filling cavities, e.g. the cavities in refrigerators.

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The invention also relates to a method for production of polyether polyols, which "consists in using a polyol in the presence of a tertiary amine as a catalyst with one or more alkylene oxides, whereupon an acid is added.

The examples explain the invention in more detail.

In the examples, polyol A is the polyol prepared according to example 1 (a), polyol B is that according to example 1 Cb) produced polyol, the polyol C is a mixture of polyols containing a polyol which was produced by Reacting glycerol with propylene oxide in the presence of boron trifluoride as a catalyst and a polyol that is produced was made by reacting glycerol with propylene oxide in the presence of potassium hydroxide as a catalyst. Furthermore, in The following protected trade names are used in the examples:

"Dabco" 33LV is triethylenediamine; "Dabco" WT is the formate of triethylenediamine and "Whore" 6 is ^, N-dimethylcyclohexylamine.

example 1

(a) 273 kg of sucrose were reacted with 655 kg of propylene oxide and 72 kg of ethylene oxide in the presence of 3) 0 kg of N, N-dimethyl-2-aminoethanol at a temperature of about 90 C. The polyol produced in this way (polyol A) has an average molecular weight of 1200, a certain hydroxyl number of 400 mgKOH / g and a pH of 11.4 (25% strength by weight aqueous Solution).

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(b) The above approach was repeated and added to that The polyol produced were 1.58 kg of 98% strength by weight formic acid (100% stoichiometric equivalent of the catalyst) was added. The pH of the polyol was 7-3

Example 2

The following four mixtures were made

TABEL

mixture 1 2 . 3 4th Polyol A. 70.0 70.0 _ Polyol B - - 70.0 70.0 Polyol C 30.0 30.0 30.0 30.0 Silicone oil (DO 193) 1.0 1.0 1.0 1.0 "Dabco" VT - 0.5 - 0.5 "Dabco" 33LV 0.5 - 0.5 - "Dime" .6 2.0 2.0 2.0 2.0 water 2.0 2.0 2.0 2.0

The mixtures were prepared so that the polyol A and the inflicted Polyol B mixed at 80 ⁰ C with the polyol C, and the mixture at 40 ° C cooled, "in the silicone oil and either" Dabco "WT or" Dabco "33LV . After the business

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mixed, ^{had been cooled to 30 0} C, "Whore" 6 and water were added.

For the following experiments, the four above mixtures were each divided into two samples. A sample from each mixture was used immediately to make a foam block (day 0). The remaining samples were heated to 5O ⁰ C, 24 maintained at this temperature and then cooled to ambient temperature, and from them also foam blocks were prepared (day 1). The foam batches were composed as follows:

Parts by weight

Mixture 1, 2,3 or 4 100

raw MDI 120

Trichlorofluoromethane 30

The foam blocks produced in this way were tested for density, content of closed cells, and thermal conductivity and permeability for water vapor. The results are shown in Table 2.

Table 2

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TABLE 2

Foam off
Mixture 1 day 1 Foam off
Mixture 2 Day 1 Foam off
Mixture 3 Day 1 Foam off
Mix 4 Day 1 Day 0 26.2 Day 0 21.3 Day 0 21.8 Day 0 21.8 Density (g / mni) 26.0 50.4 22.7 63.8 21.8 81.8 21.3 78.4 Content of ge
closed
Cells
(% By volume) 92.8 0.530 85.3 0.269 83.3 0.17C 83.4 0.186 Thermally conductive
ability ο
Btu inch / ftV
h / ^ö j? 0.157 10.39 0.149 8.60 0.164 3.78 0.173 6.03 Penetrates »ar-
for what
steam (pa
parallel to
Foam rise)
(ng / jYs) * 4.02 8.26 3.93 7.37 3.20 3.68 4.26 3.04 Can be penetrated through
for what-
s steam (s enk-
right to
Foam rise)
(ng / Ns) * 2.47 3.04 2.87 3.01-

* hg / Ns means nanograms per Newton second

The above results show that those prepared in accordance with the invention Foams have a good cell structure.

86XXV

Patent claims

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Claims (15)

Claims 1. Process for the production of polyurethane foams by mixing two packs (a) and ("b) under foam-forming Determinations, characterized in that the package (a) is one with a tertiary amine Polyether polyol produced as a catalyst, to which an acid and a silicone oil have been added, and the package (b) an organic polyisocyanate, wherein either the package (a) contains a polymerization catalyst or the reaction mixture prepared by mixing the packing (a) with the packing (b) is a polymerization catalyst is added. 2. The method according to claim 1, characterized in that a polyether polyol is used, that is made by reacting a polyol having at least four hydroxyl groups with one or more alkylene oxides. 3. The method according to claim 2, characterized in that a polyether polyol is used, which is made by reacting sucrose with a mixture of propylene oxide and ethylene oxide. 4-. A method according to claim 3, characterized GEK "Θ η η ζ η et calibration that use a polyether polyol, which is prepared by reacting sucrose with a mixture of propylene oxide and ethylene oxide in the ratio 70: 309846/10 96 - 13 - 42 889 5. The method according to any one of claims 1 to 4-, characterized gekenn.zeich that a polyether polyol is used, for the production of which trimethylamine is used as a catalyst or N, N-dimethyl-2-aminoethanol was used. 6. The method according to any one of claims 1 to 5, characterized characterized in that the acid added to the polyether polyol in pack (a) is formic acid. 7. The method according to any one of claims 1 to 6, characterized in that the amount of the polyether polyol in pack (a) added acid at least 20% of the stoichiometric equivalent of that for preparation of the polyether polyol used as a catalyst is tertiary amine. 8. The method according to any one of claims 1 to 7> thereby characterized in that the amount of the polyether polyol in pack (a) added silicone oil 1.0 to 3.0 parts by weight of ge 100 parts by weight of polyether polyol. 9. The method according to any one of claims 1 to 8, characterized in that in the pack (a) in addition at least one polyalkoxylated glycerine is present. 10. The method according to claim 9? characterized in that the polyoxyalkylated glycerin is prepared is by reacting glycerol with one or more alkylene oxides in the presence of a catalyst. which is not a tertiary amine. 11. The method according to any one of claims 9 or 10, characterized characterized in that the polyoxyalkylated 309846/1096 Glycerin is present in an amount of 30 to 50 parts by weight per 100 parts by weight of polyether polyol. 12. The method according to any one of claims 1 to 11, characterized in that the polymerization catalyst is an amine. 13. The method according to claim 12, characterized in that g e k e η η draw t, "that the package (a) is a mixture of triethylenediamine and contains dimethylcyclohexylamine. 14. The method according to claim 12 or 15, characterized in that the pack (a) is a mixture of triethylenediamine, which is neutralized with formic acid and contains dimethylcyclohexylamine. 15. The method according to any one of claims 1 to 14, characterized characterized that one for the purpose of creating foam-forming Conditions Includes water in pack (a) and / or trichlorofluoromethane in pack (a) and / or pack (b). 309846/10 96