FI86072B - Improved method for esterification of colophony - Google Patents

Description

1 86072

This invention relates to an improved process for preparing rosin ester. In particular, improvement 5 of the present invention is in the reaction of rosin and polyhydric alcohol in the presence of phosphinic acid (H 3 PO 2) and a phenol sulfide compound as a combined catalyst to shorten the reaction time of rosin pentaerythritol ester formation and form rosin ester with improved color and oxidation stability.

Rosin is a mixture of C20 monocarboxylic acids with a predominantly condensed ring structure, typical of levoprimar and abietic acids, both of which are susceptible to numerous chemical transformations. The rosins to which this invention relates include rosin, extraction resin and tall oil resin, or rosin acids contained therein, such as, for example, abietic acid, pimaric acid, sapinic acid, and the like.

The natural separation of the hydrophilic components of the juice and the corresponding vegetable fluids and the gradual conversion from the back layer of the wood to increasingly hydrophobic solids are due to the variety of resins, resins and. : generic formation processes.

'The resin intermediate of this process is characterized by 25 sandacles flowing from the cut holes to the southern slope.' pine trunks in the southeastern United States, France, and other countries. Sandarakki contains about 80% (resin) resin and about 20% turpentine.

Resin resin can be due to either the natural evaporation of the oil from the extract or the slow warping of the surface wood and heartwood ducts. Pinus strains are valuable enough to be collected, digested. ' . and extractable with hexane or higher boiling paraffins to obtain extraction resin, wood turpentine and other terpene-related compounds by fractional distillation. In the sulphate process of papermaking, pine wood is boiled with a base, whereby crude tall oil and crude sulphate turpentine are obtained as a by-product. Fractionation of crude tall oil gives tall oil resin and fatty acid-5 son.

The chemical transformation of resin, wood and tall oil resin according to this invention is esterification. The advantageous product properties obtained by esterification of rosin for various applications have led to the development of many esterification methods, in particular treatment with polyhydric alcohols. U.S. Patents 2,369,125, 2,590,910 and 2,572,086 disclose the esterification of rosin with glycerol and pentaerythritol, in addition to other polyhydric alcohols, and are usually preceded by a rosin disproportionation step.

U.S. Patent 3,780,012 discloses pretreatment of tall oil resin with paraformaldehyde and subsequent distillation prior to the esterification reaction to improve the color of the product. U.S. Patent 3,780,013 discloses the differential addition of a phenol sulfide compound during pentaerythritol esterification of tall oil resin. The color of the products of these methods was claimed to be M-scale U.S.D.A. by. In the present invention, the rosin color standards referred to are U.S.D.A. standards ranging from X, which is the lightest, to D, ... 25, which is the darkest color. The color scale is denoted X, WW, WG, N, M, K, I, H, G, F, E and D. Due to the light color of the rosin products of the process according to the invention, the rosin XA, XB and XC mean lighter than X color, and XC is the lightest color.

U.S. Patent 4,172,070 discloses the use of arylsulfonic acid in place of conventional basic esterification catalysts, such as calcium oxide, to reduce. pentaerythritol esterification of tall oil resin to obtain a rosin * ... niester with improved oxygen stability, color and melting point. However, this work is confused with the unusually large amount of pentaerythritol used (35% equivalent excess) used, which in itself would significantly increase products with ring and ball melting points of 77 to 86.5 ° C were obtained.

With normal commercial pentaerythritol esters of rosins, the ring and sphere melting points are between 95-105 ° C.

It is an object of the present invention to provide a new process for the preparation of rosin esters. It is a further object of the present invention to use a catalyst which accelerates the reaction rate of rosin esterification, resulting in a reduced reaction time. It is an object of the present invention to further reduce the amount of polyhydric alcohol used in the reaction, which results in reduced costs and higher, more favorable melting points, i. 95-105 ° C.

The method according to the invention is characterized by what is set forth in the characterizing part of claim 1.

All of the above objects are achieved by the observation that phosphinic acid (also called hypophosphorous acid) reacts synergistically with the phenol sulfide compound as a combined catalyst to accelerate the reaction rate of rosin esterification. In particular, rosin reacts with at least an equivalent amount of polyhydric alcohol, preferably glycerol or pentaerythritol, in the presence of 0.1 to 2.0% phosphinic acid and 0.05 to 1.0% phenol sulfide based on the weight of rosin, about 180 to about 300 ° At C to form a rosin ester that is the same or lighter in color than the starting rosin.

Phosphinic acid is a strong, reducing acid which is useful because of its antioxidant or color-reducing properties in the preparation of pale fatty acids. 35 potaurates (U.S. Patent 3,232,968), carboxylic acid residues 4,86072 with poly (oxyalkylene) compounds (GB Patent 979,673 and U.S. Patent 3,071,604), acrylic and methacrylic esters of glycols (JP Patent 73,11084), or light alkyl resins (JP Patent 123997). Phosphinic acid 5 has also been used as a tall oil treatment agent to convert impurities and dyes therein to a non-distillate form and to promote decarboxylation of the resin acids present (U.S. Patent 2,441,197).

A new process for the esterification of rosin is now presented, in which phosphinic acid is used together with a phenol sulfide compound as a catalyst for esterification.

The resin, extraction and tall oil resin materials to which this invention relates may be subjected to other treatments prior to esterification. For example, in addition to the distillation treatment referred to in fractional extraction processes, the rosin material may have undergone disproportionation, hydrogenation, or polymerization, or some combination of these and / or other treatments.

Polyhydric alcohols which can be used are ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylene glycol, glycerol, pentaerythritol, alcohol of the above-mentioned combinations. The amount of alcohol used in the esterification can be * · *; vary widely, but usually an excess of no more than about 20% of the equivalent total is necessary.

In general, the esterification is carried out by adding rosin to the reaction vessel, up to 50% equivalent excess of polyhydric alcohol, preferably 15 to 20% equivalent excess, and 0.1 to 2.0% phosphinic acid and 0.05 to 1.0 %. *. phenol sulphide based on the weight of rosin. The reaction temperature is raised from about 180 ° C to about 300 ° C, preferably from about 250 ° C to about 280 ° C, for up to about 15 86072 hours or until the rosin acid number is decreased to about 15 or less. Longer reaction times can be used, but additional time and energy costs eliminate the benefits achieved. The preferred amount of phosphinic acid is about 0.2 to 0.5% by weight of rosin, and no advantage is obtained when using 0.5% or more of phosphinic acid. The preferred amount of phenol sulfide is from about 0.2% to about 0.5% based on the weight of the rosin.

Phenol sulfide is disclosed in U.S. Patent 3,780,013, which is incorporated herein by reference. As mentioned in the above patent, the treatment agent can be represented by the structure: Ί (HO) (HO) (OH) 15 (try 7 S * - (Aryl) -s * - (^ ryl) (R) «(R). P (R) n - wherein n is an integer from 1 to 3, p is an integer from 0 to 100, preferably from about 5 to 20, and the sum of m + n in each aryl 20 is from 1 to 5, x is 1, 2 or 3 and R is a hydrocarbon group, e.g. alkylcycloalkyl and substituted alkyl, e.g. C 1-8, wherein the substituents are cycloalkyl, aryl, alkaryl, etc., etc. R preferably contains 1 to 22 carbon atoms Preferred alkyl groups are straight-chain secondary and tertiary alkyl groups. containing up to 8 carbon atoms Preferred aryl groups are those containing from 6 to 18 carbon atoms, typically phenyl, naphthyl and anthracyl Typical cycloalkyl groups contain from 3 to 8 carbon atoms in the ring, e.g., cyclopropyl, cyclopentyl and cyclohexyl.

The esterification reaction should preferably be carried out in an inert atmosphere obtained by nitrogen discharge into the reaction vessel before the addition of the reagents and by spraying with nitrogen during the reaction. Since light color is a desirable property for rosin barriers and the color is sensitive to the presence of oxygen, such presence must be minimized.

Since the advantage of the combined phosphinic acid and phenol sulfide catalyst is the minimal reduction in color value during esterification, the color of the rosin ester depends mainly on the color of the starting rosin. When the rosin is esterified, the combined catalysts of the process of the invention form an ester that is similar in color or lighter in color to the starting rosin.

In a preferred embodiment of the process according to the invention, the starting rosin is melted in an inert atmosphere in a reaction vessel and then 0.2% (by weight of rosin) of phosphinic acid (50% active in water), 0.5% (by weight of rosin) of phenol sulphide and 15-20% are added. equivalent excess of pentaerythritol. A very slow inert jet of 15 such as nitrogen or carbon dioxide is maintained when the mixture is heated to 250 ° C with stirring, and this temperature is maintained for about 3 hours. The reaction temperature is then raised to 275 ° C until the acid number of the reaction product has dropped from 15 or less, or about 2-12 hours. About 20 to 15 hours after the start of the reaction, the inert gas jet is replaced by a steam jet and then about 0.053% of solid sodium hydroxide (or other basic compound) by weight of rosin is added to neutralize the phosphinic acid catalyst, and the mixture is cooled to 220-230. To 25 ° C and sprayed with nitrogen to remove moisture. (Alternatively, a 50% aqueous solution of sodium hydroxide may be used).

The following examples illustrate the unexpected color improvement in rosin esters made by the process of the invention as well as the reduced reaction time.

Unless otherwise stated, parts are by weight.

:: Example 1 ‘In a suitable reaction vessel, 500 parts of a tall oil resin having a U.S.D. The A. color was WW, at 200 ° C with a typ * * * pipette. 65 parts of pentaerythritol were added again at 200 ° C. The mixture was heated to 250 ° C with stirring for 3 hours, after which the temperature was raised to 275 ° C and held until the acid number of the product was 15. The total reaction time was 43 hours and the final 5 ester had a U.S.D.A color of I.

Example 2 This and the following example demonstrate the advantages of using a conventional rosin esterification catalyst in the reaction.

The reaction was carried out as in Example 1, except that 1.076 parts of calcium formate were added as a catalyst at 200 ° C before the addition of pentaerythritol. The reaction time at 274 ° C required to achieve an acid number of 15 for the reaction product was only 6.5 hours out of a total reaction time of 9.5 hours. The final ester had a U.S.D.A. color of M to K and a ring and sphere melting point of 100 ° C.

Example 3

The reaction was carried out as in Example 2, except that 1 part of calcium hydroxide was added as a catalyst instead of calcium formate. The total reaction time required to reach acid number 15 was 10 hours. The U.S.D.A. color of the final ester was I.

-: Thus, the catalysts of Examples 2 and 3 give a shorter reaction time, but the color of the product does not achieve --- 25 real advantages.

Example 4

In order to determine the advantages of using arylsulfonic acid as a catalyst for esterification of rosin (as disclosed in U.S. Patent 4,172,070), the reaction was performed as in Example 1, except that pentaerythritol was added to molten rosin and stirred well at 200 ° C. , 1 part of paratoluenesulfonic acid was added. The time required to reach an acid number of 15 or less was 12 hours. The final 35D ester in U.S.D. The A. color was WW - WG.

8 86072

Although the reaction time was shortened and the color of the product was better than that obtained with the catalysts of Examples 2 and 3, little or no color reduction (lightening) was observed from the starting rosin.

5 Example 5

To determine whether an advantage was obtained with the catalyst combination of arylsulfonic acid and phenol sulfide, the reaction was carried out as in Example 4, except that after the addition of paratoluenesulfonic acid 10 phenol sulfide (Vultad®12, amylphenol sulfide polymer sold by Pennwalt in 0.5 one hour later at 275 ° C and finally 4 hours later at 275 ° C. The total reaction time required to achieve a hap path of less than 15 was 15 to 10 hours and the U.S.D.A. color of the final ester was X to WW.

Thus, no significant improvement was observed for either catalyst when used alone.

Example 6

In order to demonstrate the synergistic catalytic and color-improving effect of the combination of phenol sulfide and phosphin-20-nitric acid in rosin esterification, the reaction was carried out as in Example 5, except that 1 part of 50% active phosphinic acid was added instead of paratoluenesulfonic acid. Instead of differential addition, all phenol sulfide (1.5 parts) was added with other reagents at the beginning of the reaction. After the reaction proceeded for 3 hours at 250 ° C, the temperature was raised to 275 ° C for four hours to give a final ester having an acid number of less than 13 and a U.S.D.A. color from X-B to 30 X-C.

Example 7. In order to demonstrate the advantage of the process according to the invention in the esterification of the resin, the reaction was carried out as in Example 6, except that a resin having a U.S.D.A. color of X-A to X-B was used.

· · 9 86072

A significant improvement in the reaction time required to achieve the desired acid number for the product and a significant improvement in color (i.e., whitening) of the product using the catalyst combination of this invention indicate an unexpected and non-apparent synergistic catalytic effect on rosin esterification.

Although the invention has been described herein with reference to various specific materials, methods, and examples, it is to be understood that the invention is not limited to particular materials, combinations of materials, and methods selected for this purpose. Numerous variations of such details may be used, as will be appreciated by those skilled in the art.

Claims (13)

A process for esterification of rosin with a polyhydric alcohol, characterized in that the rosin and polyhydric alcohol are heated in the presence of a catalytic amount of phosphinic acid and phenolic sulfide compound in an inert environment. Process according to claim 1, characterized in that the reaction is carried out for a period of 10 to 5 hours at a temperature of 180 - 300 ° C in the presence of 0.1 - 2.0% phosphinic acid and 0.05 - 1.0% phenolic sulfide compound, and then meadow is injected and a basic compound is added in sufficient quantity to neutralize the phosphonic acid. 15 3. A method according to claim 1, characterized in that the rosin is esterified through with a 50% equivalent overdose of a polyhydric alcohol at a temperature of 250-280 ° C. 4. A process according to claim 2, characterized in that the rosin and polyhydric alcohol are heated for as long as an ester product is obtained, the acid number of which is 15 or less. 5. A method according to claim 4, characterized in that the rosin is esterified through with a 50% equivalent overdose of pentaerythritol in the presence of 0.2 - 0.5% phosphinic acid and 0.2 - 0.5% phenolic sulfide compound, and the reaction is carried out under an inert gas jet. Process according to claim 4, characterized in that the esterification reaction is carried out at a temperature of 250-280 ° C. 7. A process according to claim 5, characterized in that the inert gas is selected from a group which includes carbon dioxide and nitrogen. 8. A method according to claim 1, 2, 3 or 4. Characterized in that the esterification of the colophon is preceded by a phase in which the colophon is pretreated. Method according to Claim 8, characterized in that the pretreated rosin is selected from a group which includes disproportionate rosin, hydrated rosin and polymerized rosin. 10. A process according to claim 4, characterized in that, of the polyhydric alcohol, a maximum of 50% equivalent overdose is currently calculated on the equivalent weight of the rosin, and the use of a phenolic sulfide compound of the structure (HO). (H0) n (OH) n (Arylj— Sx - ^ ArylV Sx - {- Ary 1J (R). (R). 'P <R). J where n is an integer 1-3, p is an integer 0 - 100, x is 1-3, the sum m + n of each acrylic is 1 - 5, aryl is selected from a group including phenyl, naphthyl and anthracyl , and R is a hydrocarbon radical of 1-22 carbon atoms. 20 Method according to any of claims 1-6 or 10, characterized in that the rosin is selected from a group which includes pine resin, raw resin and extraction resin. Process according to any one of claims 1-6, 25 or 10, characterized in that the polyhydric alcohol is pentaerythritol and is present in a 15-20% equivalent overdose. Process according to any one of claims 10-12, characterized in that the reaction is carried out for 5-15 hours, whereby an ester product whose acid number is 15 or less is obtained.