Petroleum resins of improved color and process for making the same

Abstract: An petroleum resin of improved color and process for making the same are provided. The improvement in color is the result of a "dry" quench process in which the polymerizate of an olefinic, diolefinic, aromatic or mixed hydrocarbon feedstock polymerized in the presence of a Friedel-Crafts catalyst is quenched by admixing the polymerizate with a phosphite instead of the familiar water wash quenching procedure.

Description: The present invention relates generally to petroleum resins suitable as tackifiers for adhesive formulations and methods for their production. More particularly, the present invention relates to a novel quenching procedure which results in a petroleum resin having improved color properties. The present invention is primarily concerned with petroleum resins derived from aliphatic monomers, aromatic monomers and mixtures thereof. These petroleum resins are well-known in the art and are described in numerous patents and publications such as, for example, United States Patent Nos. 4,391,961; 4,419,503; 4,514,554; 4,558,107; 4,562,233; 4,636,555; 4,684,707; and 4,714,749. Petroleum resins are generally produced by polymerizing olefinic, diolefinic, aromatic and/or mixed feedstocks in the presence of a Friedel-Crafts catalyst, usually an aluminum chloride or boron trifluoride, at temperatures of between about -40°C to about 100°C and pressures ranging from atmospheric up to about 100 psig (0.69 N/mm²). As a key step in the above process, the resulting polymerizate is quenched to deactivate the active catalyst residue and convert the catalyst to a more easily removable form. Prior art quenching procedures involve the washing of the polymerizate with large volumes of water or combinations of water and an alcohol or alkali solution to deactivate and remove the catalyst from the polymerizate. Such quenching procedures are more fully taught in the aforementioned patents. The water wash ("wet") quenching procedures, however, often result in dark colored products. Additionally, the large volumes of water utilized in the quench procedures, generally on the order of about 10% to about 200% of the polymerizate, results in substantial treatment and disposal problems. The present invention overcomes these shortcomings by utilizing a "dry" quench procedure involving the addition of minor amounts of a phosphite to the petroleum resin polymerizate as more fully described below. Summary of the Invention The present invention provides a quench process for the production of petroleum resins which results in a lighter colored product. The present invention also provides a quench process for the production of petroleum resins which can alleviate many of the wastewater treatment and disposal problems of prior art water wash quenching procedures. The present invention finally provides an improved color petroleum resin produced by the quench process as described below. In accordance with the present invention, a process for quenching a polymerizate of hydrocarbon feedstock polymerized in the presence of a Friedel-Crafts catalyst is provided which, in its overall concept, comprises the step of admixing the polymerizate with an effective amount of a phosphite. The phosphite and polymerizate are agitated for a time sufficient to promote the reaction or to react with each other after which time the polymerizate may be water washed and/or otherwise treated in a manner familiar in the art to clean, separate and recover the resulting petroleum resin. The water wash, no longer required to deactivate and remove the residual catalyst, becomes an optional step. By omitting the water wash and filtering the phosphite-treated polymerizate, the aforementioned wastewater treatment and disposal problems can be substantially alleviated. The phosphite may be added to the polymerizate over a broad range of proportions so long as the quenching is sufficient. Of course, this depends upon the particular resin and phosphite chosen. Conveniently, the phosphite is added to the polymerizate preferably in amounts ranging from about 0.05 to 6.0, more preferably from about 0.25 to about 5.0, most preferably from about 0.25 to about 3.0, moles of phosphite per mole of the Friedel-Crafts catalyst utilized for the polymerization. Phosphites used with the present invention are those of the general formula P(OR)(OR₁)(OR₂), wherein R, R₁ and R₂ are selected from hydrogen or a hydrocarbon group preferably having from 1 to 20 carbon atoms, and wherein at least one of R, R₁ or R₂ is such a hydrocarbon group. Particularly preferred are those phosphites wherein R, R₁ and R₂ are the same hydrocarbon group. Also particularly preferred are those phosphites wherein the hydrocarbon groups have from 1 to 6 carbon atoms. The "dry" quench procedure utilizing the phosphite in accordance with the present invention produces a petroleum resin of improved color properties over its water washed counterpart. The improved color petroleum resins of the present invention, as a by-product of the quench reaction, will also include minor amounts of a resin chain having the following general formula: wherein R₃ comprises a petroleum resin chain, and wherein R₄ and R₅ are selected from hydrogen or a hydrocarbon group preferably having from 1 to 20 carbon atoms, more preferably from 1 to 6 carbon atoms. These and other features and advantages of the present invention will be more readily understood by those skilled in the art from a reading of the following detailed description with reference to the accompanying drawing. Brief Description of the Drawing Figure 1 is a graphical representation of the measured Gardner colors for various petroleum resins as described below in Examples 12-25. Detailed Description of the Preferred Embodiment As mentioned earlier, the petroleum resins of the present invention are produced by polymerizing olefinic, diolefinic, aromatic and mixed feedstocks in the presence of a Friedel-Crafts catalyst in any one of a number of well-known polymerization reactions. The results is an aliphatic, aromatic or mixed character petroleum resin. The various hydrocarbon feedstocks and reaction conditions are described in detail in the aforementioned patents, and reference may be had to them for greater detail other than provided herein. Briefly, the hydrocarbon feedstocks are generally obtained by steam cracking kerosene, gas oil, naptha and other light refinery streams at elevated temperatures and pressures. Ethylene and propylene are prominent components of these steam cracked refinery streams, which also may contain higher molecular weight hydrocarbons such as, for example, butenes, pentenes, hexenes, napthenes, aromatics and other cyclic and acyclic hydrocarbons of increasing molecular weights. The various fractions are generally distilled into groups with similar boiling points. The petroleum resins of the present invention are produced by (co)polymerizing these steam cracked distillates, predominately the C₅ to C₉ fractions, in the presence of from about 0.25% to about 2.5% by weight of a Friedel-Crafts type catalyst such as, for example, an aluminum chloride, aluminum bromide, and boron triflouride, or solutions, complexes or slurries thereof. An especially preferred Friedel-Crafts catalyst is aluminum trichloride (AlCl₃). The (co)polymerization reactions are carried out at temperatures ranging from about -40°C to about 100°C and pressures ranging from atmospheric upon to about 100 psig (0.69 N/mm²) for from about 0.5 hours to about 3 hours. Of course, the temperatures, pressures and times may vary depending upon the initial feedstocks and desired characteristics of the final resin; however, these parameters are easily determinable by one skilled in the art. In accordance with the present invention, the resulting polymerizate from the copolymerization reaction is then quenched by admixing the polymerizate with an effective amount of a phosphite of the general formula P(OR) (OR₁) (OR₂), wherein R, R₁ and R₂ are selected from hydrogen or a hydrocarbon group, and wherein at least one of R, R₁ or R₂ is such a hydrocarbon group preferably an alkyl group. The hydrocarbon group preferably has from 1 to 20 carbon atoms, more preferably from 1 to 6 carbon atoms. Particularly preferred are those phosphites wherein R, R₁ and R₂ comprise the same hydrocarbon group. Suitable phosphites include, for example, trimethyl phosphite, triethyl phosphite, tris(2-ethylhexyl) phosphite, tributyl phosphite, triisooctyl phosphite, triisopropyl phosphite, triphenyl phosphite and dimethyl phosphite. Especially preferred is trimethyl phosphite. The phosphites are preferably utilized in amounts ranging from 0.05 to 6.0, more preferably from 0.05 to 5.0, most preferably between 0.05 to 3.0, moles of phosphite per mole of Friedel-Crafts catalyst utilized in the (co)polymerization reaction. The phosphite, preferably in liquid form, is added to the polymerizate and the two admixed for a time sufficient for the phosphite to react with the catalyst, generally on the order of from 0.5 minutes to 60 minutes, more preferably from 0.5 minutes to 20 minutes. The resulting quenched polymerizate may then be processed in a manner familiar in the art such as, for example, filtration and/or centrifugation, to produce the finished petroleum resin. As an optional subsequent step, the phosphite quenched polymerizate may be water washed in the manner familiar to the art. This water wash step, however, is no longer necessary and may be omitted if desired, saving wastewater treatment and processing costs. As a result of this quenching procedure, a petroleum resin of improved color properties is produced. Also, by some unknown mechanism, the phosphite reacts with a resin polymer chain to produce a minor amount of a resin chain having the following general formula: wherein R₃ comprises the petroleum resin chain (aliphatic, aromatic and/or a mixture of both), and wherein R₄ and R₅ are selected from hydrogen or a hydrocarbon group, preferably the same hydrocarbon group. The hydrocarbon group, as mentioned before, preferably has from 1 to 20 carbon atoms, more preferably from about 1 to 6 carbon atoms. The aliphatic, aromatic and mixed aliphatic/aromatic petroleum resins of the present invention, therefore, will contain minor amounts of this resin chain. The use of the aforedescribed phosphites in the quench process of the present invention does not appear to substantially affect any of the properties of the petroleum resin other than the color which, as demonstrated below, is significantly lightened. The foregoing more general discussion of this invention will be further exemplified by the following specific examples and comparative example offered by way of illustration of the above-described invention. EXAMPLES A series of phosphite compounds was tested as quench agents to determine their effect on the color of various aliphatic and aromatic petroleum resins. The results are presented in Table IV. A general procedure for the tests is described below. From 900-1000 g of a C₅ to C₉ hydrocarbon feedstock was polymerized in a batch reactor in the presence of a Friedel-Crafts catalyst comprising either AlCl₃ or BF₃. Before polymerization, the catalyst in solution or slurry form was first introduced into the batch reactor which was maintained clean and moisture free under a blanket of dry nitrogen gas. When AlCl₃ was used as the catalyst, anhydrous AlCl₃ was mixed with a solvent such as benzene or toluene under constant stirring to form a uniform slurry. The amounts of AlCl₃ and solvent making up the slurry were 0.5-1.0 and 5 wt%, respectively, of the total polymerization batch. When BF₃ was used as the catalyst, a commercial etheral solution of BF₃ (available from Aldrich Chemical Company, 1988 Catalog No. 17550-1) was directly injected into the batch reactor. The amount of etheral BF₃ used was similar to that of AlCl₃. To start the polymerization, the hydrocarbon feedstock was pumped into the reactor that contained the catalyst solution or slurry. Polymerization occurred immediately when the hydrocarbon was in contact with the catalyst, as evidenced by the evolution of heat and the appearance of the characteristic red color of the polymerizate. The feed pump was set at such a rate that the addition of the total desired amount of feedstock was completed in 30 minutes. During this 30 minute time period, the reactor was maintained at a temperature of 40±5°C and a pressure of atmospheric up to 30 psig (0.21N/mm²). Without changing the reaction conditions or adding additional feedstock, the polymerization was allowed to continue for an additional 30 minute heat-soaking period. At the end of the heat-soaking period, the red-colored polymerizate was divided into two or more portions for the particular quenching experiment. A first portion, utilized as a control, was quenched with an equal volume of water or water-isopropanol mixture (4:1 to 1:1). The organic layer was separated from the aqueous layer and washed with an equal volume of water. After again separating the organic layer from the aqueous layer, the polymerizate was stripped first with nitrogen then with steam. Nitrogen stripping, designed to remove all unreacted molecules, was carried out by passing nitrogen gas through the polymerizate while the polymerizate was gradually heated from room temperature up to 250°C. Steam at 250°C was then passed through the polymerizate to further remove the undesired low molecular weight oligomers. The color of the finshed resin was measured using a Hunter Lab Model D25 Optical Sensor expressed in Gardner units. A second portion was quenched with a particular phosphite in accordance with the methods of the present invention. A predetermined amount of this phosphite was added to about 400 grams of the second portion, and the mixture was stirred for about 1 to about 40 minutes. Various phosphite/catalyst molar ratios were tested. When the phosphite was utilized, it was noticed that the polymerizate became light in color and a complex was formed as a result of the quench reaction. The resulting polymerizate was separated from the sludge-like complex by centrifugation and/or filtration, then stripped and finished as described above. As an option in some examples, the phosphite-quenched polymerizate was subsequently water-washed as described above before finishing. The color of the finshed resin was measured as with the control. These abbreviations as set forth in Table IV below have the following meaning: TMP -- trimethyl phosphite TEP -- triethyl phosphite TEHP -- tris(2-ethylhexyl) phosphite TBP -- tributyl phosphite TIOP -- triisooctyl phosphite TIPP -- triisopropyl phosphite TPP -- triphenyl phosphite DMP -- dimethyl phosphite TEPA -- triethyl phosphate WW -- water washing QA -- quench agent RESIN 1 -- an aromatic petroleum resin produced from premium (desulfurized) C₉ hydrocarbon feedstock. The actual feedstock utilized is a plant stream of varying composition. A typical composition is set forth below in Table I. Active Component Weight % Styrene 4%-10% a-Methylstyrene 1%-5% m-Methylstyrene 7%-15% o-Methylstyrene 1%-5% p-Methylstyrene 2%-10% B-Methylstyrene 1%-7% Indene 7%-15% Divinylbenzene 0%-5% Methylindenes 0%-10% RESIN 2 -- another aromatic petroleum resin produced from regular (non-desulfurized) C₉ hydrocarbon feedstock, the composition of which is essentially the same as set forth in Table I. RESIN 3 -- an aliphatic petroleum resin produced from C₅ to C₆ fraction having a boiling point of 22°C to 65°C. The actual C₅ to C₆ feedstock utilized is a plant stream of varying composition. A typical composition is set forth In Table II below. Active Component Weight % 2-Methylbutane 29% 2-Methyl-1-butene 4% Isoprene 1% 2-Methyl-2-butene 19% Cyclopentadiene 1% Cis/trans 1,3-pentadiene 20% Cyclopentene 7% Other C5/C6 Olefins 13% Other Alkanes 7% RESIN 4 -- a petroleum resin produced from a mixture of aliphatic and aromatic hydrocarbon feedstocks, such as those set forth in Tables I and II above. A typical composition is set forth in Table III below. Active Component Weight % 2-Methyl-2-butene 1%-4% Cis/trans 1,3-pentadiene 5%-15% Cyclopentene 3%-10% Styrene 4%-8% a-Methylstyrene 1%-4% m-Methylstyrene 5%-12% o-Methylstyrene 1%-4% p-Methylstyrene 1%-8% B-Methylstyrene 1%-6% Indene 5%-12% Examples 1-9 and C1 Nine different quench agents including seven trialkyl phosphites (1-8), one dialkyl phosphite (9) and one trialkyl phosphate (C1) were tested to determine their effect on the premium aromatic resin designated as RESIN 1. The results are presented above in Table IV. The tests were conducted following the general procedure described above. This, 900 grams of hydrocarbon feedstock was polymerized at 40°C under an atmosphere of nitrogen in the presence of 0.5% AlCl₃ catalyst. A 400 gram portion of the resulting polymerizate was water-washed, stripped and finshed. This portion was used as the control. For Example 1, another 400 gram portion of the polymerizate was treated with 2.8 grams of TMP which was equivalent to 1.5 moles of TMP per mole AlCl₃ used in the polymerization. During the treatment, the TMP/polymerizate mixture was stirred for about 20 minutes to promote the reaction. After centrifuging and filtering, the resulting polymerizate was stripped and finished. The same procedure was repeated for Examples 2, 4-9 and C1 to test the effects of other quench agents. In Example 3, a water-washing step was included subsequent to the quench step. The results as presented in Table IV clearly show the positive (lightening) effects on the color of petroleum resins when a phosphite is utilized as the quenching agent. In fact, the only negative result in color change appears in the Comparative Example (C1) which utilizes a phosphate instead of a phosphite. Phosphates, of course, are phosphorous compounds but outside the scope of the phosphites of the present invention. In other words, the Comparative Example (C1) shows that not all phosphorous compounds give the positive color results as with the use of phosphites in accordance with the present invention. Examples 10 and 11 In these examples, TPP was tested as a quench agent for RESINS 2 and 3. RESINS 2 and 3 were produced as above for RESIN 1, except that RESIN 3 was polymerized with 0,6% AlCl₃ catalyst under 12 psig (0.08 N/mm²) nitrogen pressure. These examples, together with Example 8, show that the phosphite quench in accordance with the present invention is effective in reducing the Gardner color of resins of different types and grades. Examples 12-25 As can be seen from Table IV, and as graphically depicted in Figure 1, these examples demonstrate the effectiveness of TMP as a quench agent for different resins (RESINS 1, 2 and 3) at varying concentration levels. Examples 26 and 27 In these examples, DMP was tested on RESIN 1 at two concentration levels by the same procedure as in Example 9. Although apparently less effective than the trialkyl phosphites of Examples 1, 2 and 4-8, DMP was demonstrated to improve resin color when utilized as the quench agent. Examples 28 and 29 As seen in Example 3, quenching the polymerizate with TMP followed by a water washing step proved effective in reducing the color of RESIN 1. RESIN 4, utilized in this example, was produced from a mixture of C₅ and C₉ feedstocks and polymerized by the same procedure as described in Example 10 or 11. The quench procedure was similar to that of Example 3 except that a lower TMP concentration was used in the present example. As demonstrated by the results presented in Table IV, the color of RESIN 4 was significantly improved by the aforedescribed TMP plus water wash quench procedure in accordance with the present invention. Examples 30 and 31 In these examples, RESIN 1 was polymerized as before except that etheral BF₃ was used instead of AlCl₃. The amount of etheral BF₃ used was approximately equal to the amounts of AlCl₃ used in earlier examples. The polymerizates were quenched with TMP (Ex. 30) and TMP plus water washing (Ex. 31) as described before. As shown in Table IV, the quenching of BF₃ catalyzed polymerizations in accordance with the procedures of the present invention also proved quite effective in reducing resin color. Given below are two additional examples describing the resin aged color improvement due to the phosphite-quenching process in this invention. Example 32 A control sample and a phosphite-quenched sample of RESIN 1 were aged by being heat treated in a furnace at 175°C for 16 hours. RESIN 1 is a C9 (or aromatic) resin described in Example 1. The aged color turned out to be 15.8 Gardner for the control and 10.4 Gardner for the quenched resin. The lighter aged resin color is, in fact, the result of using the phosphite-quenching process in the present invention. Example 33 As an additional example, RESIN 3, a C5 (or aliphatic) resin described in Example 24 was heat treated in the same manner. The lighter aged color of 10.4 Gardner observed for the quenched resin compared to the aged control color of 12.2 Gardner confirms the resin color improvement by this invention.

Claims: Process for quenching a polymerizate of a hydrocarbon feedstock polymerized in the presence of a Friedel-Crafts catalyst, comprising the step of admixing said polymerizate with an effective amount of a phosphite of the general formula P(OR)(OR₁)(OR₂), wherein R, R₁ and R₂ are selected from hydrogen or a hydrocarbon group, and wherein at least one of R, R₁ or R₂ comprises said hydrocarbon group. Process according to claim 1, wherein said hydrocarbon group comprises from 1 to 20 carbon atoms, preferably from 1 to 6 carbon atoms. Process according to claim 1 or claim 2, wherein R, R₁ and R₂ are the same said hydrocarbon group. Process according to any of the preceding claims, wherein said admixing step comprises the step of admixing said polymerizate with from 0.05 to 6.0 moles of said phosphite per mole of said Friedel-Crafts catalyst, preferably from 0.05 to 5.0 moles of said phosphite per mole of said Friedel-Crafts catalyst and especially from 0.05 to 3.0 moles of said phosphite per mole of said Friedel-Crafts catalyst. Process according to any of the preceding claims, wherein said admixing step comprises the step of admixing said polymerizate with said phosphite for a time sufficient to substantially react with said Friedel-Crafts catalyst, preferably from 0.5 minutes to 60 minutes and especially from 0.5 minutes to 20 minutes. Process according to any of the preceding claims, wherein said hydrocarbon feedstock comprises an olefin, diolefin, aromatic or mixture thereof and/or said Friedel-Crafts catalyst comprises an aluminum chloride and/or a boron trifluoride. A process for producing a petroleum resin of improved color quality, comprising the steps of: polymerizing a hydrocarbon feedstock in the presence of a Friedel-Crafts catalyst to produce a polymerizate, said hydrocarbon feedstock comprising an olefin, diolefin, aromatic or mixture thereof; and quenching said polymerizate according to any of claims 1 to 6 with a phosphite of the general formula P(OR)(OR₁)(OR₂), wherein R, R₁ and R₂ are the same or different of hydrogen or a hydrocarbon group, and wherein at least one of R, R₁ or R₂ comprises said hydrocarbon group. Petroleum resin including a resin chain of the general formula: wherein R₃ comprises an aliphatic, aromatic or mixed aliphatic/aromatic petroleum resin chain, and wherein R₄ and R₅ are selected from hydrogen or a hydrocarbon group. Petroleum resin according to claim 8, wherein said hydrocarbon group comprises from 1 to 20 carbon atoms, preferably from 1 to 6 carbon atoms and/or wherein R₄ and R₅ comprise the same said hydrocarbon group. Petroleum resin according to claim 8 or 9, wherein said petroleum resin chain comprises an aliphatic, aromatic or mixed petroleum resin chain, preferably produced by the polymerization of a olefinic, diolefinic, aromatic or mixed hydrocarbon feedstock in the presence of a Friedel-Crafts catalyst.

Inventors: MURPHY RAY FRANCIS, TENG HARRY HO-I, MURPHY, RAY, FRANCIS, TENG, HARRY, HO-I
Applicants: EXXON CHEMICAL PATENTS INC, EXXON CHEMICAL PATENTS INC.
Application year: 1989
Main classification: C08F240
IPC codes: C08F240, C08F6, C08K5, C08L57