CA2156155A1

CA2156155A1 - A process for the production of light-colored polyol esters

Info

Publication number: CA2156155A1
Application number: CA 2156155
Authority: CA
Inventors: Joerg-Dieter Klamann; Johann Klein; Peter Daute; Erwin Fleischer; Peter Wedl
Original assignee: Individual
Current assignee: Henkel AG and Co KGaA
Priority date: 1993-02-15
Filing date: 1994-02-07
Publication date: 1994-08-18
Also published as: EP0683763A1; WO1994018153A1; DE4304468A1

Abstract

Light-coloured polyolesters can be produced by esterification of fatty acids or fatty acid glycerin esters in the presence of between 0.001 to 0.1 % by weight, based on the fatty acid, of lithium salts with polyols, after which the polyolesters are treated with bleaching agents in a known manner. The materials are suitable as plastics adjuvants.

Description

- 21~61~

A process for the production of light-colored polyol esters Field of the Invention This invention relates to a process for the produc-tion of light-colored polyol esters, in which fatty acids or fatty acid glycerol esters are esterified or trans-esterified with polyols in the presence of lithium salts and the reaction products are subsequently treated with bleaching agents, to the products obtained by this process and to their use as auxiliaries for plastics.

Prior Art Various auxiliaries are used in the production and processing of plastics. Their functions include, for example, the reduction of friction during extrusion, the antistatic finishing of the polymers and the protection of the polymers against yellowing under the effect of UV
radiation. The most important ingredients of such auxiliaries besides metal soaps and phosphorus compounds are polyol esters which are normally prepared by esteri-fication of fatty acids or by transesterification of fatty oils with polyols, generally glycerol, in the presence of catalytic quantities of tin salts.
Basically, tin salts are suitable esterification or transesterification catalysts. For example, new rapeseed oil rich in oleic acid can be transesterified with glycerol in the presence of l to 2% by weight of tin oxalate, based on the oil, over a period of 8 hours to form a mixture of mono- and diglycerides in satisfactory yields. Unfortunately, a disadvantage in this regard is the high tin content of the products which is undesirable for applicational reasons. Accordingly, instead of laboriously removing the tin from the partial glycerides, the catalysts are normally used in small quantities of, typically, 0.02 to 0.04% by weight. Although partial esters with a tolerably low tin content can be produced in this way, the advantage of the low catalyst concentra-tion is offset by the disadvantage of considerably longerreaction times. Another very crucial disadvantage is that the use of tin catalysts, especially where unsatu-rated starting materials are used, leads to products of inadequate color quality which can only be lightened with hydrogen to a very limited extent, if at all.
Accordingly, the problem addressed by the present invention was to provide a process for the production of light-colored polyol esters which would be free from the disadvantages mentioned above.
` 15 Description of the Invention The present invention relates to a process for the production of light-colored polyol esters in which fatty acids or fatty acid glycerol esters are subjected to esterification or transesterification with polyols in the presence of 0.001 to 0.1~ by weight, based on the fatty compounds, of lithium salts and the resulting polyol esters are subsequently treated with bleaching agents in known manner.
It has surprisingly been found that not only are lithium salts capable of catalyzing the esterification or transesterification reaction and considerably shortening the reaction time in - comparatively - very low concen-trations, they also lead to polyol esters which are very much easier to bleach, for example with hydrogen perox-ide, than the known products. Another advantage of the process according to the invention is that there is no need for neutralization and/or removal of the lithium salts in the polyol esters because the small quantities used do not adversely affect either the properties of the 21~61~S

products or their further processing behavior.

Raw materials The fatty acids are aliphatic carboxylic acids corresponding to formula (I):

RlCO-OH ~I) in which R1CO is a linear or branched aliphatic, optional-ly hydroxy-substituted acyl radical containing 6 to 22 carbon atoms and 0 or 1 to 5 double bonds.
Typical examples are caproic acid, caprylic acid, isononanoic acid, capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, petroselic acid, linoleic acid, linolenic acid, elaeo-stearic acid, ricinoleic acid, 12-hydroxystearic acid, arachic acid, gadoleic acid, behenic acid and erucic acid and the technical mixtures thereof obtained, for example, in the pressure hydrolysis of fats and oils or in the oxidation of aldehydes from Roelen's oxo synthesis.
Fatty acids containing 16 to 18 carbon atoms and 0 or 1 double bond, for example technical tallow fatty acid, are preferably used.
The fatty acid glycerol esters are triglycerides corresponding to formula (II):

I

CH-o-co-R3 (II) C~2o-Co-R4 in which R2C0, R3Co and R4Co independently of one another represent linear or branched aliphatic, optionally hydroxy-substituted acyl radicals containing 6 to 22 carbon atoms and 0 or 1 to 5 double bonds.

- 215$155 Wo 94/18153 4 PCT/EP94/00345 Typical examples are synthetic, but preferably natural fatty acid glycerol esters of vegetable or ~n;m~l origin, for example based on palm oil, palm kernel oil, coconut oil, rapeseed oil from old and new plants, sunflower oil from old and new plants, castor oil, soybean oil, peanut oil, olive oil, linseed oil, beef tallow or fish oil, and chemically modified triglycerides of the so-called "soya polyol~ type which are obtained by epoxidation of soybean oil and subsequent opening of the oxirane rings with suitable nucleophiles, for example alcohols. Vegetable triglycerides with a high percentage content of unsaturated fatty acids, especially those based on rapeseed oil and sunflower oil from new plants, are preferably used.
Suitable polyols are compounds containing at least 2 and preferably 3 to 5 hydroxyl groups. Typical exam-ples are glycerol, oligoglycerols with an average degree of oligomerization of 1.5 to 10, trimethylol propane and pentaerythritol. Glycerol is preferably used. Accord-ingly, the preferred products obtainable by the process according to the invention are fatty acid glycerides, more particularly technical mixtures of mono- and digly-cerides.

Lithium salts Suitable lithium salts besides lithium hydroxide are lithium soaps, i.e. salts of lithium with optionally hydroxy-functionalized fatty acids containing 6 to 22 carbon atoms and 0, 1, 2 or 3 double bonds. Typical examples are the lithium salts of caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, elaidic acid, petroselic acid, linoleic acid, linolenic acid, 12-hydroxystearic acid, ricinoleic acid, arachic acid, gadoleic acid, behenic acid or erucic acid. The lithium 21~6155 salts may be used in the form of aqueous or alcohol solutions. By virtue of the fact that they are easy to dose, the lithium salts of unsaturated fatty acids -which are liquid in any case - are preferably used. The lithium soaps may be directly added to the reaction mixture, although they may also be formed in situ, for example from lithium hydroxide and a fatty acid ester.
The quantity of lithium salts used may be from 0.001 to 0.1% by weight, preferably from 0.002 to 0.05% by 10 weight and more preferably from 0.004 to 0.01% by weight, based on the starting materials. Since lithium lons can interchange with the alkali metal ions present in glass, which can lead to a reduction in the concentration of lithium ions, it is advisable to carry out the process in lS apparatus of steel or similarly inert materials. The use of lithium carbonate together with aluminium oxide for the autocondensation of glycerol is known from JP Patent Abstract 13, 372 tC-627)(3270) 17.

Esterification or transesterification and bleaching The molar ratio of fatty acids or fatty acid glycer-ol esters to polyols may be from 10:1 to 1:10 and is preferably from 3:1 to 1:3. The esterification or transesterification may be carried out in known manner at 25 temperatures of 100 to 250C. The esterification or transesterification may be complete, i.e. all the avail-able hydroxyl groups are saturated. However, one prefer-red embodiment of the invention seeks to achieve only partial esterification or transesterification. Partial in this context means a degree of esterification of 10 to 95 and preferably 25 to 75% of the available hydroxyl groups. It is pointed out that the expert is capable of controlling the degree of esterification through the ratio in which the starting materials are used without having to become involved in inventive activity.

~ Bleaching may also be carried out in known manner by adding, for example, 0.3 to 1% by weight and preferably 0.2 to 1% by weight, based on the polyol esters, of hypochlorite or preferably hydrogen peroxide to the polyol esters and stirring for 0.5 to 2 h.
The present invention also relates to light-colored polyol esters which are obtained by subjecting fatty acids or fatty acid glycerol esters to esterification or transesterification with polyols in the presence of 0.001 to 0.1% by weight, based on the fatty compounds, of lithium salts and subsequently treating the resulting polyol esters with bleaching agents in known manner.

Industrial applications The light-colored polyol esters obtainable by the process according to the invention improve slip behavior in the production of polymers, are suitable for the antistatic treatment of plastics and have a color-stabil-izing effect against W radiation.
Accordingly, the present invention also relates to the use of the light-colored polyol esters obtainable by the process according to the invention as auxiliaries for plastics in which they may be present in quantities of 0.1 to 5% by weight and preferably in quantities of 0.5 to 1.5% by weight, based on 100 parts of plastic.
Typical examples of auxiliaries of the type men-tioned are lubricants, antistatic agents and W stabiliz-ers. In this connection, the light-colored polyol esters may be used together with other typical starting materi-als, for example metal soaps, optionally oxo- or hydroxy-substituted fatty acids, optionally chemically modified hydrotalcites, alkyl phosphates, alkyl phosphites, diketones, epoxidized fatty acid lower alkyl esters or glycerol esters and the like. Suitable plastics are, in particular, PVC and polycarbonate.

21SS1~5 ~ The following Examples are intended to illustrate the invention without limiting it in any way.

ExamPles Example 1:
a) Transesterification. 475.3 g (0.5 mole) of rapeseed oil from new plants (oleic acid content approximate-ly 60% by weight) and 27.3 g (0.3 mole) of glycerol were introduced into a l-liter four-necked-spherical flask equipped with a stirrer and thermometer and surmounted by a descending condenser. At the start of the transesterification reaction, another 4.0 g (0.04 mole) of glycerol and 12 g (0.04 mole) of technical oleic acid (Edenor~ TiO5, a product of Henkel KGaA, Dusseldorf, FRG) and - as catalyst -0.02 g of lithium hydroxide, corresponding to 0.004%
by weight based on the triglyceride, were added to the mixture. The reaction mixture was heated with stirring to 200C and the water of reaction was continuously removed by application of a light vacuum. After a reaction time of 4 h, the content of free glycerol in the mixture was still about 1%
by weight. The crude reaction product was cooled to 90C and filtered after the addition of 0.5% by weight, based on the reaction product, of bleaching earth.
The clear light-yellow oil obtained had a Lovibond color value (1 inch cuvette) of yellow 5.8 and red 1.8.

b) Bleaching. Aqueous hydrogen peroxide (35% by weight) was added to part of this oil in a quantity of 0.5% by weight, based on the oil, followed by stirring for 30 minutes at 90C. A light vacuum was `_ 21S61~i~

~ then applied, the mixture was heated for 90 minutes to 105C and the water was removed. The resulting clear and distinctly lightened oil had a Lovibond color value (1 inch cuvette) of yellow 3.3 and red 0.3.

Comparison Example Cl:
a) Transesterification. Example 1 was repeated using 475.3 g of new rapeseed oil, 31.3 g of glycerol and 12 g of oleic acid. Instead of the lithium salt, however, 0.1 g of tin oxalate (corresponding to 0.02% by weight, based on the triglyceride) was used as the catalyst. In this case, however, the limit-ing value of the residual glycerol content of around 1% by weight was only reached after a reaction time of 13 h.

b) Bleaching. Part of the oil was bleached with hydrogen peroxide as in Example 1. The resulting clear, but not lightened oil had a Lovibond color value (1 inch cuvette) of yellow 3.4 and red 1Ø

Claims

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1. A process for the production of light-colored polyol esters, in which fatty acids or fatty acid glycerol esters are subjected to esterification or transesterifi-cation with polyols selected from glycerol, trimethylol propane and pentaerythritol in the presence of 0.001 to 0.1% by weight, based on the fatty compounds, of lithium salts and the resulting polyol esters are subsequently treated with bleaching agents in known manner.

2. A process as claimed in claim 1, characterized in that fatty acids corresponding to formula ~
R1CO-OH (I) in which R1CO is a linear or branched aliphatic, optional-ly hydroxy-substituted acyl radical containing 6 to 22 carbon atoms and 0 or 1 to 5 double bonds, are used.

3. A process as claimed in claim 1, characterized in that fatty acid glycerol esters corresponding to formula (II):

( II) in which R2CO, R3CO and R4CO independently of one another represent linear or branched aliphatic, optionally hydroxy-substituted acyl radicals containing 6 to 22 carbon atoms and 0 or 1 to 5 double bonds, are used.

4 A process as claimed in claims 1 to 3, characterized in that the fatty acids or fatty acid glycerol esters and the polyols are used in a molar ratio of 10:1 to 1:10.

5. A process as claimed in claims 1 to 4, characterized in that lithium hydroxide is used as the lithium salt.

6. A process as claimed in claims 1 to 4, characterized in that lithium soaps of optionally hydroxy-substituted fatty acids containing 6 to 22 carbon atoms and o, 1, 2 or 3 double bonds are used as the lithium salts.

7. A process as claimed in claims 1 to 6, characterized in that the esterification or transesterification reac-tion is carried out at a temperature of 100 to 250°C.

8. Light-colored polyol esters obtainable by subjecting fatty acids or fatty acid glycerol esters to esterifica-tion or transesterification with polyols selected from glycerol, trimethylol propane and pentaerythritol in the presence of 0.001 to 0.1% by weight, based on the fatty compounds, of lithium salts and subsequently treating the resulting polyol esters with bleaching agents in known manner.

9. The use of light-colored polyol esters obtained by the process claimed in claims 1 to 7 as auxiliaries for plastics.