CA1175852A

CA1175852A - Alkenyl succinic anhydride composition and method for its preparation

Info

Publication number: CA1175852A
Application number: CA000433920A
Authority: CA
Inventors: William A. Sweeney
Original assignee: Chevron Research and Technology Co
Current assignee: Chevron USA Inc
Priority date: 1982-08-20
Filing date: 1983-08-04
Publication date: 1984-10-09
Also published as: IT8322586A0; GB2126260A; SE461668B; NL8302862A; NL190013C; FR2531984A1; IT1163919B; GB8322326D0; SE8304450D0; FR2531984B1; DE3328716A1; NL190013B; SE8304450L; GB2126260B; IL69397A0; IL69397A

Abstract

ABSTRACT OF THE DISCLOSURE
An improved liquid alkenyl succinic anhydride composition having superior paper sizing properties.
There is also disclosed a method for the airing of paper and a method for imparting water-repellency to cellulosic fabrics using the composition of the invention. This invention also provides a process for the preparation of alkenyl succinic anhydride from maleic anhydride and a mixture of straight chain alpha olefins in the C13 to C22 range which comprises separating the alpha olefins into a lower boiling fraction and a higher boiling fraction, isomerizing the higher boiling fraction, recombining the two fractions and reacting them with maleic anhydride.

Description

~ .32 ALKENYL SUCCINIC ANHYDRIDE CO~tPOSITION
_AND METHOD FOR ITS PREPARATION
05 ' ' ~ACKGROUND OF THE INVENTION
..
This invention relates to ~n improved liquid alkenyl succinic anhydride mixture having superior paper sizing properties and a process for its preparation.
l~ This invention also relates to an improved method for the sizing oE paper and paperboard products. A ~urther aspec~
of this invention relates to an improved method for imparting water-repellency to cellulosic fabrics.
It is known in the art that long strAight chain alkanyl succinic anhydrides can be used as effective paper sizing agents. See, for example, U.S. Paten~
Nos. 3,102,064; 3,821,069; 3,968,005; and 4,040,900 (Re. 29,960). These alkenyl succinic anhydrides have also been used as fabric treating agents. See U.S, Patent

2~ No. 2,903,382. The useful molecular weight range of the alkenyl group on these sizing agents has variously been described as encompassing 8 to 35 carbon atoms.
It is also known that these prior art sizing agents are best applied in a highly dispersed form, such as an aqueous emulsion. However, alkenyl succinic anhydrides made from straight chain alpha olefins are solids at ambient temperatures and are therefore not effective in forming these emulsions. In view of this, commercial alkenyl succinic anhydride paper sizing agents are made from isomerized straight chain alpha olafins (i.e~, straight chain internal olefins) or from branched chain olefins. See, for example, the frequent reference to "isooctadecenyl succinic anhydride" in UOS.
Patent No. 3,102,064.
It has been taught that the molecular weight of the alkenyl group of the more effective or preferred alkenyl succinic anhydride sizing agents corresponds to a carbon number in the 13 to 22 carbon atom range. Mixtures of several carbon numbers have also been described.

S8S;2 See, for example, the reference to C15_20 alkenyl 5uccinic anhydride in U.S. Patent No. 4,040,900 (Re. 29,~60).
SUMMARY OF THE INVENTION
The present invention provides a two-component alkenyl succinic anhydride composition with superior paper sizing properties which.comprises:
~ A) the reaction product o maleic anhydride and straight chain alpha olefins in the C13 to C18 range preferably having an average molecular weight o from about 182 to 238; and (b) the reaction product of maleic anhydride and straight chain internal olefins or branched chaln olefins in th~ C14 to C22 range preferably havin~ an average molecular weight oE ~rom about 224 to 308;
wherein component (B) has a mol~cular weight of at least 10 units higher than component (A).
~ ; Preerably the above mixture contains about 5 to .~ 40~ o component (.A)`and, more preferably, about 10 to 35 .~ of component (Aj.
;~` :
The present invention is also concerned with a ; ~ method of sizing.- paper~by dispersing within the wet paper ~ pulp and alkenyl succinic anhydride composition as described -.~ above.

: The inst:an~ invention is fur*her concerned with a method o treating cellulosic abric to render the same :
water-repellent by impregnating the fabric with the novel alkenyl succinic anhydride compositions of the invention.
The present invention also provides.a pr~ferred process for the~preparation of the instant alkenyl succinic : anhydride compositlon from maleic anhydride and a mixture of straight chain alpha olefins in the C13 to C22 range ~hich : comprises:

(A) introducing -the alpha olefins in-to a distillation zone wherein at least a por-tion of the lowest boiling alpha olefin is vaporized and taken overhead;
(B) isomerizin~ -the remaining bottoms Erom -the distilla-tion zone to reduce the alpha olefin content to less than 15%
of the total olefin bottoms content;

- 2a -'~. ...

.D~

-3-(C) recombining the alpha olefin overhead fraction recovered from step ~A) with the isomerized olefin bottoms 05 fraction of step (s); and ~ D) reacting the recombined olefins from step (C) with maleic anhydrida to provide the alkenyl succinic anhydride product.
In another aspect of the process of the invention, the unisomerized alpha olefin overhead ~raction recovered from step (A) and the isomeri~ecl olefin Ibottoms fraction of step (B) are each independently reactel~ with maleic anhydride, and the resulting alkenyl suc~cinic anhydride products are then combined to provide the lS alkenyl succinic anhydride of the invention.
Preferably, the alpha olefin content in step (B) is reduced to less than 10~, and more preferably, less than 5%1 of the total olefin bottoms content.
Among other factors, the present invention is based on my surprising discovery that certain s~raight chain alpha olefin-derived alkenyl succinic anhydrldes, heretofore considered not useful, can be combined in specific mixtures with other alkenyl succinic anhydrides to provide a superior paper sizing product.
An additional advantaga of the present invention is the fact that, when straight chain alpha olefins are being used as the starting feedstock for making liquid alkenyl succinic anhydrides, less olefin processing is required prior to forming the alkenyl succinic anhydride.
DETAILED DESCRIPTION OF THE INVENTION
The composition of the present invention may be prepared by simply combining the described alkenyl suc-cinic anhydride components or, alternatively, by combining the precursor olefins and then making the desired alkenyl succinic anhydride. For example, a broad range straight chain alpha olefin mixture, which may be obtained from wax cracking, Fischer-Tropsch synthesis or ethylene oligomeri-zation, could be distilled to yield light and heavv frac-tions. The heavy fraction is then isomerized to move the

4~ double bond to internal positions and recombined with the 01 ~4-light fraction before makin~ the alkenyl succinic anhydride composition of the present invention.
Q5 The olefin feed for component (A) of the present composition should be predominantly ~traight chain l-olefin.- Minor amounts of chain branching or internal olefin, such as is found in commercial "alpha olefins,"
may also be present.
The olefin feed Eor either component (A~ or (B) may consist of a single carbon number, a mixture o con-tiguous carbon numbers or may consist of any combination of carbon numbers within that range.
The olefin feed for component (~) may b~
IS stralght chain or branchecl. Branched chain olefin may be obtained from various sources such a~ by oligomerization of lower olefins in the C3 to Cll range. IE straight chain, the olefin should be substantially free of alpha olefin. These straight chain olefins may be obtained from 2~ n-paraffins by processes well known in the art, such as dehydrogenation and chlorination-dehydrochlorination.
Alternatively, the straight chain olefins may be made by isomerizing alpha olefins using acidic or basic catalysts, in accordance with the preferred process of the invention.
According to the process of this invention, the olefin feed for component (B) is a straight chain internal olefin obtained by isomerizing straight chain alpha olefins in the C14 to C22 range. This isomerization may be accomplished using acidic or basic catalysts. The isomerization should be sufficient to leave no more than about 15% alpha olefin remaining, preferably less than 10~, and more preferably, less than 5~ alpha olefin.
These olefins may be augmented by the inclusion of branched chain olefins or internal straight chain olefins obtained from other sources, as dascribed above. In general, the olefin feed for component ~s) should be sub-stantially free of straight chain alpha olefin.
The novel sizing agents display all oF the features and advantages of the cited prior art sizing agents. Moreover, the novel sizing agents of this

5~5~

~1 5-invention impart to paper sized therewith a particularly good resistance to acidic liquids such as acid inks, 05 citric acid, lactic acid etc. as compared to paper sized with the si~ing agents of the cited prior art~ In addi-tion to the properties already mentioned, these sizing agents may also be used in combination with alum as well as with any of the pigments, fillers and other ingredients which may be added to paper. The sizing agents of the present invention may also be used in conjunction wlth other si2ing agents so as to obtain additive sizing efects. A still further advantage is that thay do not detract from the strength o the paper and when used wlth certain adjuncts will, in ~act, increase the strength of the finished sheets. Only mild drying or curing conditions are required to develop full sizing value.
The actual use of these sizing agents in the manufacture of papar is subject to a number of variations in technlque any of which may be further modified in light of the specific requirements of the practitioner. ~t is important to emphasiæe, however, that with all of these procedures, it is most essential to achieve a uniform dispersal of the sizing agent throughout the fiber slurry, in the form of minute droplets which can come in intimate contact with the fiber surface. Uniform dispersal may be obtained by adding the sizing agent to the pulp with vigo-rous agitation or by adding a previously formed, fully dispersed emulsion. Chemical dispersing agents may also be added to the fiber slurry.
Another important factor in the effective utilization of the sizing agents of this invention involves their use in conjunction with a material which is either cationic in nature or is, on the other hand, capa-ble of ionizing or dissociating in such a manner as toproduce one or more cations or other positively charged moieties. These cationic agents, as they will be herein-after referred to, have been found useful as a rneans for aiding in the retention of sizing agents herein as well as for bringing the latter into close proximity t:o the pulp 5~

~1 -6-fibers. Among the materials which may be employed as cationic agents in the sizing proces;, one may list alum, oS aluminum chloride, long chain fatty amines, sodium alumi-nate r substituted polyacrylamide, chromic sulfate, animal glue, cationic thermosetting resins and polyamide poly-mers. Of particular interest for use as cationic agents are various cationic starch derivatives including primary, secondary, tertiary or quaternary amine starch derivatives and other cationic nitrogen substituted starch deriva-tives, as well as cationic sulEonium and phosphoni~m starch derivatives. Such derivatives may be prepared from all types o~ starches including corn, tapioca, pota~o, waxy maize, wheat and rice. Moreover, they may be in their original granule form or they may be converted to pregelatinized, cold water soluble products.
Any of the above-noted cationic agents may be added to the stock, i.e., the pulp slurry, either prior 2U to, along with, or after the addition of the sizing agent. However, in order to achieve maximum distribution, it is preferable that the cationic agent be added either subsequent to or in direct combination with the sizing agent. The actual addition to the stock of either the cationic agent or the sizing agent may take place at any point in the paper making process prior to the ultimate conversion of the wet pulp into a dry web or sheet. Thus, for example, these sizing agents may be added to the pulp while She latter is in the headbox, beater, hydropulper or stock chest.
In order to obtain good sizing, it is desirable that the sizing agents be uniformly dispersed throughout the fiber slurry in as small a particle size as is pos-sible to obtain. One method for accomplishing this is to emulsify the sizing agent prior to its addition to the stock utilizing either mechanical means, such as high speed agitators, mechanical homogenizers, or by the addi-tion of a suitable emulsifying agent. Where possible, it is highly desirable to employ the cationic agent as the emulsifier and this procedure is particularly successful -5~5~

Ql _7_ where cationic starch derivatives are utilized. Among the applicable non-cationic emulsifiers which may be used as oS emulsifying agents for the sizing agents, one may list such hydrocolloids as ordinary starches, non-cationic starch derivatives, dextrines, carboxymethyl cellulose, gum arabic, gelatin, and polyvinyl alcohol as well as various surfactants. Examples of such surfactants include polyoxyethylene sorbitan trioleate, polyoxyethylerle sorbitol hexaoleate, polyoxyethylene sorbitol laurate, and polyoxyethylene sorbitol oleate-laurate. When such non-cationic emulsiflers are used, it is oten deslrabl0 to separately add a cationic agent to the pulp slurry after the addition to the latter of the emulsified sizing agent.
In preparing these emulsions with the use of an emulsi-fier, the latter is usually first dispersed in water and the sizing agent is then introduced along with vigorous agitation. Alternatively, the emulsification techniques described in U.S. Patent No. 4,040,900 may be employed.
Further improvements in the water resistance of the paper prepared with these novel sizing agents may be obtained by curing the resulting webs, sheets, or molded products. This curing process involves heating the paper at temperatures in the range of from 80 to 150C for periods of from 1 to 60 minutes. However, it should again be noted that post curing is not essential to the success-ful operation of this invention.
The sizing agents of this invention may, of course, be successfully utilized for the sizing of paper prepared from all types of both cellulosic and combina-tions of cellulosic with non-cellulosic fibers. The cellulosic fibers which may be used include bleached and unbleached sulfate (kraft), bleached and unbleached sulfite, bleached and unbleached soda, neutral sulfite, semi-chemical chemiground-wood, ground wood, and any combination of these fibers. These designations refer to wood pulp fibers which have been prepared by means of a variety of processes which are used in the pulp and paper s~

Ol -8-industry. In addition, synthetic fibers of the viscose rayon or regenerated cellulose type can also be used.
05 All types of pigments and fillers-may be added to the paper which is to be sized with the novel sizing agents of this invention. Such materials include clay, talc, titanium dioxide, calcium carbonate, calcium sul-fate, and diatomaceous earths. Other additives, including alum, as well as other sizing agents, can also be used with these sizing agents.
With respect to proportions, the sizing agents may be employed in amounts ranging from about 0.05 to about 3.0~ o the dry weight of the pulp in ~he Einished sheet or web. While amounts in excess of 3% may be used, the benefits of increased sizing properties are usually not economically justified. Within the mentioned range the precise amount of size which is to be used will depend for the most part upon the type of pulp which is being utilized, the specific operating conditions, as well as the particular end use for which the paper is destined.
Thus, for example, paper which will require good water resistance or ink holdout will necessitate the use of a higher concentration of sizing agent than paper which does not. The same factors also apply in relation to the amount of cationic agert which may be used in conjunction with these sizing agents. The practitioner will be able to use these materials in any concentration which is found to be applicable to his specific operating conditions.
.However, under ordinary circumstances a range of from 0.5 to 2.0 parts by weight of cationic agent per 1.0 part of sizing agent is usually adequate. It can be noted that the cationic agent is present in a quantity of at least 0.025% of the dry weight of the pulp in the paper.
The alkenyl succinic anhydride compositions of the present invention may also be used to impart water-repellency to cellulosic fabrics. The water-repellent compositions described above may be applied to the cloth in aqueous emulsion~ similar to those used for paper sizing. The emulsion may be sprayed onto the fabric or ~7~

~1 9 the fabric may be dipped into the emulsion in order to distribute the derivative evenly throughout the fabric.
OS The impregnated fabric is then withdrawn from the solution and air dried~ After air drying the cloth i9 then heated, preferably to a temperature in excess of 100C, to effect a curing of the impregnated agent within the cloth. It has been found that one may conveniently use a temperature of about 125C for a period of 15 to 20 minutes. At lower temperatures longer periods of time are required to e~fect the curing process. To be commercially practical the cur-ing time should be as short as possible and ~enerally less than one hour. At higher temperature~ the heat curing may be accomplished in shorter periods of time. The upper limit of temperature at which the heat curing process may be carried out is limited to the temperatures at which fabrics begin to brown or become discolored. Using the composition of the present invention, it is preferred to - 20 impregnate the fabric with from about 0.7 to 2.5~ by weight of the fabric of the alkenyl succinic anhydride.
The following examples are provided to illustrate the invention in accordance with the principles of this invention but are not to be construed as :Limiting the invention in any way except as indicated by the appended claims.
EXAMPLES
Example 1 This example describes the preparation of a standard straight chain alkenyl succinic anhydride suit-able for sizing applications.
The feed olefin was derived from cracking petro-leum wax and originally contained about 88% straight chain alpha olefin. It consisted of a mixture of homologs from C15 to C20 containing about 18g C15, 19% C16, 18% C17, 18% C18, 15% Clg and 12~ C20~ This mixture was isomerized using an acidic catalyst until the alpha olefin content was reduced to 7~. The double bond had been moved to the 2-position and further internal positions.

The above straight chain internal olefin mixture (3299, 1.35 moles) was heated with maleic anhydride (98g, 05 1.0 mole) in an autoclave for 3 1/4 hours at 230C~ Over 95~ of the maleic anhydride reacted with the olefin to give an alkenyl succinic anhydride product. This crude product was stripped of unreacted maleic anhydride and olefin by heating up to 260C a-t 25mm Hg with nitrogen I0 sparging over a 40-minute period~
The remaining alkenyl succinic anhydride3 wa~ a straw-colored llguid with a pour point of about 5C which remained fluid but formed some solids on standing over-night at this temperature.
IS This product is very similar to normal commer-ci~l straight chain alkenyl succinic anhydride. Xt glves good paper sizing results in a variety of tests, such as those described in U~S. Patent No. 4,040,900 ~Rs. 29,960).
Example 2 2~ An alkenyl succinic anhydride was made as described in Example 1, except that tha carbon number range of the feed olefin consisted of ~5~ C15r 30~, C16, 29% C17, and 15% C18. The alpha olefin content r~maining after isomerization was 7%. The derived alkenyl succinic anhydride was a clear liquid which did not produce solids on standing overnight at 5C.
Exam~le 3 An alkenyl succinic anhydride was made from the same straight chain alpha olefins as descrihed in 3U Example 1, except that the olefin isomerization step was omitted. The alkenyl succinic anhydride product was a solid, completely unsuitable for sizing by the normal aqueous emulsion techniques.
Example 4 The alpha olefin feed used in Exampls 1 was distilled to produce a lower boiling fraction which ~as 88~ C15 and 9% C16, with an average molecular waight of 212. An alkenyl succinic anhydride was made from this olefin using the steps of Example 1 except that the '10 5~

isomerization step was omitted. This alkenyl succinic anhydride was a solid, unsuitable for sizing.
05 Example 5 An example of the composition of the present invention was made by using the alkenyl succinic anhydride of Example 4 as component A and a Cl6_l8 alkenyl succinic anhydride as component B. The Cl6_l~ alpha olefin frac-tion was in the bottoms from distilling out the ClS cut o~
Example 4~ This Cl6_l8 fraction contained about 34~ Cl6, 34% Cl7, and 27~ Cl8, with an averag0 molecular weight of 237. The Cl~_l8 raction waq isomerized to recluce the alpha ole~in content to 7%~ and an alkenyl succinic anhy dride was made a~ in Example l. The final alkenyl succinic anhydride mixture contained 22.5% of component A
and 77.5~ of componént B. This composition was a clear liquid at room temperature. It remained fluid but formed some solids on standing overnight at 5C.
2~ Example 6 Another example of the composition of the present invention was made as described in Example 5, except that the Cl6_l8 olefin used to make the alkenyl succinic anhydride of component B was isomerized more completely before reactin~ with maleic anhydride. In this case, instead of 7% alpha olefin rsmaining, only 2 alpha olefin remained after isomerizing. This Cl6_l8 olefin was reacted with maleic anhydride and the resulting alkenyl succinic anhydride was mixed with the alkenyl succinic anhydride of Example 4 in a 22.5/77,5 ratio as in Example 5. This composition was a liquid at room temperature and did not form any solids on standing overnight at 5C.
Example 7 Paper sizing experiments and size effectiveness evaluations were run using techniques described in U.S.
Patent No. 4,040,900 (Re. 29,960). For each alkenyl succinic anhydride tested, eight results were obtained.
The alkenyl succinic anhydride was added to paper at two different levels: 0.2~ and 0.4~, based on dry fiber ~ ~7S~

~1 -12-weight~ A cationic starch adjuvant was employed at twotimes the alkenyl succinic anhydride level, in each 05 case. At both alkenyl succinic anhydride levels, tests were also made with 0.5% added alum. The sized papers were evaluated using both the Hercules size test ~80~
reflectance end point), and the potassium permanganate test described in U.S. Patent No. 4,040,900.
For each alkenyl succinic anhydride, the times to obtain each end-point were averaged to give tho results shown in Table 1.

Tabl~ 1 15 Alkenyl Succinic Anhydride 'rime, in seconds, to end-polnt Example No. Carbon Ran~e (averaqe of 8 tests)

6 15-18 165 The results of Table 1 demonstrate that the alkenyl succinic anhydrides of the present invention, namely Examples 5 and 6, give superior sizing effective-ness compared to the known alkenyl succinic anhydride compositions of Examples 1 and 2.
Example 8 A composition similar to those descrihed in Examples 5 and 6 was made by blending 20~ of the alkenyl succinic anhydride from Example 4 with 80% of an alkenyl succinic anhydride derived from a branched olefin mixture in the C15 to C20 range made by oligomerizing propylene.
This composition was a liquid at room temperature and did not form any solids on standing overnight at 5C.

- ~0

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An alkenyl succinic anhydride composition comprising:
(A) the reaction product of maleic anhydride and straight chain alpha olefins in the C13 to C18 range; and (B) the reaction product of maleic anhydride and straight chain internal olefins or branched chain olefins in the C14 to C22 range;
wherein component (B) has a molecular weight at least 10 units higher than component (A).

2. The composition of Claim 1, wherein the composi-tion contains from about 5 to about 40% of component (A).

3. The composition of Claim 2, wherein the composi-tion contains from about 10 to about 35% of component (A).

4. The composition of Claim 1, wherein the average molecular weight of the olefin feed for component (A) is from about 182 to 238 and the average molecular weight of the olefin feed for component (B) is from about 224 to 308.

5. The method of sizing paper which comprises the step or intimately dispersing within the wet pulp, prior to the ultimate conversion of said pulp into a dry web, an alkenyl succinic anhydride sizing agent comprising:
(A) the reaction product of maleic anhydride and straight chain alpha olefins in the C13 to C18 range; and (B) the reaction product of maleic anhydride and straight chain internal olefins or branched chain olefins in the C14 to C22 range;
wherein component (B) has a molecular weight at least 10 units higher than component (A).

6. The method of Claim 5, wherein the sizing agent contains from about 5 to about 40% of component (A).

7. The method of Claim 6, wherein the sizing agent contains from about 10 to about 35% of component (A).

8. The method of Claim 5, wherein the average molecular weight of the olefin feed for component (A) is from about 182 to 238 and the average molecular weight of the olefin feed for component (B) is from about 224 to 308.

9. The method of Claim 5, wherein the sizing agent is in the form of an aqueous emulsion.

10. The method of treating cellulosic fabric to render the same water-repellent which comprises impreg-nating said fabric with an alkenyl succinic anhydride composition comprising:
(A) the reaction product of maleic anhydride and straight chain alpha olefins in the C13 to C18 range; and (B) the reaction product or maleic anhydride and straight chain internal olefins or branched chain olefins in the C14 to C22 range;
wherein component (B) has a molecular weight at least 10 units higher than component (A);
and heat-curing the impregnated fabric at temperatures lower than the temperatures at which the cellulosic fabric is discolored.

11. The method of Claim 10, wherein the composition contains from about 5 to about 40% of component (A).

12. The method of Claim 11, wherein the composition contains from about 10 to about 35% of component (A).

13. The method of Claim 10, wherein the average molecular weight of the olefin feed for component (A) is from about 182 to 238 and the average molecular weight of the olefin feed for component (B) is from about 224 to 308.

14. A process for the preparation of alkenyl succinic anhydride from maleic anhydride and a mixture of straight chain alpha olefins in the C13 to C22 range which comprises:
(A) introducing the alpha olefins into a distillation zone wherein at least a portion of the lowest boiling alpha olefin is vaporized and taken overhead;
(B) isomerizing the remaining bottoms from the distillation zone to reduce the alpha olefin content to less than 15% of the total olefin bottoms content;
(C) recombining the alpha olefin overhead fraction recovered from step (A) with the isomerized olefin bottoms fraction of step (B); and (D) reacting the recombined olefins from step (C) with maleic anhydride to provide the alkenyl succinic anhydride product.

15. The process of Claim 14, wherein the alpha olefin content in step (B) is reduced to less than 10% of the total olefin bottoms content.

16. The process of Claim 15, wherein the alpha olefin content in step (B) is reduced to less than 5% of the total olefin bottoms content.

17. The process of Claim 14, wherein the amount of olefin taken overhead in step (A) is about 5 to 40% of the total olefin used.

18. The process of Claim 17, wherein the amount of olefin taken overhead in step (A) is about 10 to 35% of the total olefin used.

19. The process of Claim 14, wherein the average molecular weight of the olefin taken overhead in step (A) is from about 182 to 238 and the average molecular weight of the bottoms olefin in step (B) is from about 224 to 308.

20, A process for the preparation of alkenyl succinic anhydride from maleic anhydride and a mixture of straight chain alpha olefins in the C13 to C22 range which comprises:
(A) introducing the alpha olefins into a distillation zone wherein at least a portion of the lowest boiling alpha olefin is vaporized and taken overhead;
(B) isomerizing the remaining bottoms from the distillation zone to reduce the alpha olefin content to less than 15% of the total olefin bottoms content;
(C) independently reacting the unisomerized alpha olefin overhead fraction recovered from step (A) and the isomerized olefin bottoms fraction of step (B) with maleic anhydride; and (D) combining the reaction products of step (C) to provide the alkenyl succinic anhydride product.

21. The process of Claim 20, wherein the alpha olefin content in step (B) is reduced to less than 10% of the total olefin bottoms content.

22. The process of Claim 21, wherein the alpha olefin content in step (B) is reduced to less than 5% of the total olefin bottoms content.

231 The process of Claim 20, wherein the amount of olefin taken overhead in step (A) is about 5 to 40% of the total olefin used.

24. The process of Claim 23, wherein the amount of olefin taken overhead in step (A) is about 10 to 35% of the total olefin used.

25. The process of Claim 20, wherein the average molecular weight of the olefin taken overhead in step (A) is from about 182 to 238 and the average molecular weight of the bottoms olefin in step (B) is from about 224 to 308.