HELP OF THE INVENTION

This invention relates to decolorized resins and methods for decolorizing resins by combining with a decolorizing agent comprising a hydride of non-metal element or a derivative thereof.

BACKGROUND OF THE INVENTION

Low color hydrocarbon resins are desired by industry, yet are difficult to obtain by current polymerization, quench, and recovery methods. There are several methods known to reduce color in such typical colored hydrocarbon resins.

Hydrogenation of resins is disclosed in U.S. Patent No. 5,171,793. However, hydrogenation is very expensive due to the required facilities investment. This method also involves at least one extra production step after quenching and more likely after recovery of the untreated (unsaturated) product.

U.S. Patent No. 5,077,386 discusses treatment of resins with phosphites to reduce color. In addition to high cost this method may be less attractive under current environmental regulations.

U.S. Patent Nos. 5,175,247, 5,270,443, and 5,294,697 discuss the use of organometallics of selected metals to remove catalyst residue from resins. These processes may be difficult to manage due to handling issues associated with the pyrophoric nature of the selected organometallic compounds. Furthermore, removal and disposal of inorganic residues increase the ultimate cost of this method. Thus, there is a need in the art to find lower cost methods to reduce resin color. It would be further advantageous if the new method did not impede subsequent polymerization of the resin thus allowing greater processing flexibility.

SUMMARY OF THE INVENTION This invention relates to a method to reduce resin color by combining the resin with a selected decolorizing agent which is preferably a hydride of non-metal element or a derivative thereof. The instant invention also relates to compositions comprising the resin and the decolorizing agent

DETAILED DESCRIPTION OF THE INVENTION

A resin solution is treated under reaction conditions with a decolorizing agent, said agent comprising a substituted or unsubstituted hydride of non-metal element or a salt of a metal element with a substituted or unsubstituted hydride of non-metal element The resin solution is can be a pre-quenched or post-quenched solution containing reactants and polymerisate or a recovered resin product that has been redissolved in a solvent. Polymerisate is defined herein as a mass of polymer wherein polymer chain growth is still in progress or the polymerization process has been completed. It is known that many of the hydrocarbon resins may be hydrogenated and/or modified by other subsequent chemical reaction. Hydrogenation is typically accomplished under pressure in the presence of a metal catalyst Acid-modified hydrocarbon resin may be prepared in accordance with process described in EP-A- 0 240 253 and U.S. Patent No. 4,629,766, which are incorporated herein by reference, or in accordance with the descriptions in the prior art documents Usted therein. Such hydrocarbon and modified hydrocarbon resins, particularly those of the petroleum resins, are additionally suitable in accordance with the invention. Additionally, mixtures of any of the foregoing will also be suitable in accordance with the invention. Hydrocarbon resin products, including unmodified, modified and fully or partially hydrogenated are widely available. For example purposes reference can be made to the Escorez® hydrocarbon resins available through Exxon Chemical Co., U.S.A., the Arkon® hydrocarbon resins available from Arakawa Chemical, Japan, the Petrosin® hydrocarbon resins available from Mitsui Petrochemical, Japan, the Hiresin® hydrocarbon resins available from Toho Petroleum, Japan, the

Regalite®, Regalrez®, Endex®, Kristalex®, Piccolastic®, Piccotex®, Hercules®, Piccopale®, Piccotac®, Picco®, Piccoumaron® Hercotac® and Adtac® hydrocarbon resins of Hercules Inc. U.S.; the Zonatac®, Zonarez®, hydrocarbon resins available from Arizona Chemical Co., U.S.A., the Wingtack hydrocarbon resins available from Goodyear Chemicals, U.S.A., and the Eastotac® hydrocarbon resins available from Eastman Chemical Products, Inc. Particularly preferred petroleum hydrocarbon resins for use in this invention includes those described in EP-A-0 196 844, specifically those having a softening point in the range of from 10°C to 140°C, preferably from 20°C to 120°C, more preferably from 20°C to 115°C, most preferably from 80°C to 115°C. These petroleum hydrocarbon resins are copolymers of a feed materials comprising C5 olefϊns and diolefins in the range

of from 70 to 100 weight percent, preferably from 70 to 90 weight percent, more preferably from 70 to 80 weight percent and monovinylaromatic compounds in the range of from 10 to 60 weight percent, preferably from 10 to 50 weight percent, more preferably from 10 to 40 weight percent based on the weight of the resin. The instant invention provides a method to reduce the color of a hydrocarbon resin comprising combining, under reaction conditions, the resin with a decolorizing agent. The decolorizing agent is selected from hydrides of non- metal elements, alkyl-substituted hydrides of a non-metal elements, and the salts of certain metals with selected hydrides of non-metal elements or alkyl-substituted hydrides of a non-metal elements. The resins that may be improved by the methods of this invention include any hydrocarbon resin and are preferably petroleum resins, terpene resins, coal tar resins, or resins made from pure monomer. The petroleum resins include C5 aliphatic hydrocarbon resins, aromatic hydrocarbon resins, C5/C9 aromatic modified aliphatic or mixed aliphatic-aromatic hyrdrocarbon resins, alicyclic and alicyclic diene containing hydrocarbon resins, and cyclopentadiene/dicyclopentadiene hydrocarbon resins. A preferred class of resin are those prepared by the thermal polymerization of monomer streams. A particularly preferred class of resin includes C5 aliphatic petroleum resins, typically polymerized from mixed C5 unsaturated hydrocarbon monomer stream using a Friedel-Crafts catalyst

The hydrocarbon resins useful in the invention are the known low molecular weight thermoplastic polymers of monomer feedstreams derived from cracked petroleum distillates, turpentine fractions, coal tar, and a variety of pure monomers. The weight average molecular weight is usually in the range of from 200 to 3000, preferably from 300 to 3000, more preferably from 500 to 2800. Physical forms of the resins range from viscous liquids to hard, brittle solids.

Polymerization feedstreams are derived from the sources described above via various known means and methods of fractionation. Friedel-Crafts polymerization is generally accomplished by use of a preferred catalyst in a polymerization solvent, and removal of the solvent and catalyst by washing and distillation. Thermal polymerization is also utilized to some extent, particularly for aliphatic and aliphatic-aromatic petroleum resins.

The preferred hydrocarbon resins are those known to be useful as tackifiers for adhesive compositions, particularly the petroleum resins derived from the deep cracking of petroleum distillates, hydrocarbon resins from pure aromatic monomer, the coumarone-indene resins from coal tar and the polyterpenes derived from

turpentine fractions. Included in petroleum resins are those that have been modified with aromatic or terpene containing feedstreams. For additional description of feedstream derivation, monomer composition, and methods of preparation reference may be made to patent literature disclosed in the above "Background of the Invention" and to technical literature, e.g., Encycl. of Poly. Sci. and Eng., vol. 7, pp. 758-782 (John Wiley & Sons, 1987). Reference may be also be made to U.S. Patents 4,078,132, 4,391,961, 5,171,793, and EP-A-0 240 253 and its corresponding application U.S. serial no. 07/065,792, filed June 24, 1987, each fully incorporated herein by reference for purposes of U.S. patent practice. For additional information about hydrocarbon resins and how they are manufactured, see the Kirk-Othmer Encyclopedia of Chemical Technology, 3rd Vol. 12, p. 852-866, which is fully incorporated by reference herein for purposes of U.S. patent practice.

Typical Freidel-Crafts catalysts include but are not limited to AICI3 or BF3, any modified version of AICI3 or BF ₃ , or Uquid complexes of AICI ₃ or BF ₃ . A particularly preferred type of resin are the aromatic modified aliphatic C5/C ₉ or Cs/Cf terpene resins prepared from steam-cracked petroleum fractions and having number-average molecular weights (M _w ) less than or equal to 900, a molecular weight distribution (MWD) less than or equal to 2.1, and an aromaticity of 10-40 weight percent aromatic monomers, preferably 15-35 weight percent, based on total molecular weight of the resin.

Resins of similar monomers meeting these physical parameters wUl also be particularly suitable. CommerciaUy available resins that are suitable include the Escorez® 1000 series (e.g. Escorez® 1102, 1304, 1310LC, 1315, and 1580) and 2000 series (e.g. Escorez® 2101, 2393, 2520, and 2596) resins of Exxon Chemical

Co. See also, the resins described in U.S. Patent No. 5,171,793. This patent is similarly incorporated by reference herein for purposes of U.S. patent practice. The most suitable resins have a ring and ball softening point (ASTM E28-92) of 10-140°C, more preferably 20-120°C, and most preferably 80-115°C. In a preferred embodiment the resin, not having been treated by the process disclosed and claimed herein, would have a Gardner color of 13 or less, preferably of 7 or less, even more preferably 5 or less, but preferably at least 2, before it is combined with the decolorizing agent. The treated resin preferably has a Gardner color of about 2.5 or less, preferably about 1.5 or less. Additionally, the resin treated by this invention will exhibit a measurable Gardner color improvement preferably at least about a 10% improvement more preferably at least a 15%

improvement , even more preferably at least about a 35% improvement in color, and most preferably at least about a 75% improvement

In additional embodiments, these color improvements are achieved without the use of other color reducing agents. For example the resin-decolorizing agent combination would be essentially free or even absent of other known decolorizing agents, such as phosphites, hydrogenation agents, and the like.

The preferred decolorizing agent of this invention is selected from hydrides of non-metal elements, alkyl-substituted hydrides of a non-metal elements, and their salts of certain metals with selected hydrides of non-metal elements or alkyl- substituted hydrides of a non-metal elements. More preferred non-metal elements are boron, silicon, nitrogen, sulfur and phosphorus.

In another embodiment the decolorizing agent is a polymer of a non-metal represented by the formulae: R(GR ₃ ) _n R or R(GR ₂ -O-) _n GR ₃ wherein G is a non-metal element preferably boron, silicon, nitrogen, sulfur, or phosphorus, more preferably silicon or boron; n is an integer from 1 to 50, preferably 5 to 25, more preferably 10; and each R, which can be the same or different is a hydrocarbon radical or hydrogen provided that at least one R attached to each G is hydrogen. Preferred hydrocarbon radicals of up to 30 carbon atoms or more include alkyl radicals, aromatic radicals, aralkyl radicals, aUphatic radicals, branched radicals, aUcyclic radicals, multi cycUc radicals and the like. Preferred G groups are boron and silicon. Preferred R groups are hydrogen and Ci, to C _j o alkyl radicals, preferably C _] to Cg , more preferably C ₂ to C5. .

Preferred salts of certain metals with selected hydrides of non-metal elements or alkyl-substituted hydrides of a non-metal elements are represented by the formula:

M+n[GR _a+1 ]- _n

wherein G is a non-metal element preferably boron, silicon, nitrogen, sulfur, or phosphorus; M is a metal, preferably a group 1 or 2 metal, preferably sodium or potassium, or a quaternary ammonium or phosphonium group wherein the organic groups can be the same or different C C _j2 alkyl or aralkyl groups or hydrogen; "n" is the valence number of M; "a" is the valence number of G, and each R, which can be the same or different, is a hydrocarbon radical or hydrogen provided that at least one R is hydrogen. Preferred hydrocarbon radicals of up to 30 carbon atoms or more include alkyl radicals, aromatic radicals, aralkyl radicals,

aliphatic radicals, branched radicals, aUcycUc radicals, multi cycUc radicals and the Uke. Preferred G groups are boron and silicon. Preferred R groups are hydrogen and Ci to C _{I Q} alkyl radicals, preferably Cj to C& more preferably C ₂ to C5. Preferred hydrides include but are not limited to sodium borohydride, Uthium borohydride, ammonia, silicon hydride, tetrabutyl ammonium borohydride and organo silanes with or without alkyl substitution such that at least one hydrogen to silicon bond remains. A preferable organo silane is (Et^SiH, where Et = ethyl. Aralkyl is defined to be a hydrocarbon having both aromatic and aUphatic structures. For the purposes of this invention a hydride is an inorganic compound of hydrogen with another element A hydride for the purposes of this invention also includes compositions wherein the element bonded to the hydrogen may also be bonded to a metal or hydrocarbon radicals of up to 30 carbon atoms or more including alkyl radicals, aromatic radicals, aralkyl radicals, aliphatic radicals, branched radicals, aUcycUc radicals, multi cycUc radicals and the Uke, provided the element maintains at least one bond to a hydrogen atom. All reference to the Periodic Table are to the Table as published in Chem. and Eng. News 63, (5), 27 1985.

Particularly preferred salts of certain metals with selected hydrides of non- metal elements or alkyl-substituted hydrides of a non-metal elements are represented by the formulae:

(1) MBH4, wherein M is Na, K, Li or N(R^ and R is a Cj to Cj alkyl radical or hydrogen, and each R, which can be the same or different is an alkyl radical or hydrogen provided that at least one of R is hydrogen; (2) MBR4. _n H _n , wherein M is Na, K or Li, n is an integer from 1 to 4 and R is a

C _] to C _] ø alkyl radical, and each R, which can be the same or different is an alkyl radical; or (3) MB(OR)4. _n H _n , wherein M is Li, Na, K or -NR4, n is an integer from 1 to 4 and R is a C^-Cι hydrocarbon radical or an aromatic, and each R, which can be the same or different, is an alkyl radical or aromatic.

Examples of preferred salts of certain metals with selected hydrides of non- metal elements or alkyl-substituted hydrides of a non-metal elements represented by formula (2), above, include:

a) Ii+[B(C ₂ H ₅ ) ₃ H]-,

b) K ⁺ [ B(CH-CH ₂ -CH ₃ ) ₃ H] ^"

CH,

The decolorizing agents described above may also be supported on a typical support such as siUca, alumina, any inert polymeric resins (such as polystyrene) or ion exchange resins. The decolorizing agents may be supported by methods known in the art. For example, to support these decolorizing agents one would suspend both the decolorizing agent and the support in a solvent or other Uquid media then evaporate the liquid or solvent off. For additional information on supported hydrides see Polvmers as Aids in Organic Chemistrv N.K. Mathur, C.K. Narang and R.E. Williams, academic Press New York, 1980, especially Chapter 12, incorporated by reference herein for purposes of U.S. patent practice. Supported silica hydrides and ion exchange resins are commercially available from Aldrich Chemical Co., Inc., Milwaukee, Wisconsin, and Ventron Corp., Beverly, Massachusetts.

According to the instant invention the decolorizing agent may be added to the monomer feed stream prior to polymerization. In another embodiment the hydrocarbon resins may be combined with the decolorizing agent some time after the monomer feed stream and catalyst are mixed to start the polymerization process, but prior to quenching the polymerization process. In another embodiment the hydrocarbon resins may be combined with the decolorizing agent at some time after quenching the polymerization process but prior to recovery of the resin product. In another embodiment the hydrocarbon resins may be combined with the decolorizing agent at some time after recovery of the resin product by redissolving the recovered resin, or reaction product of polymerization, into a homogeneous solution in a solvent. The solvent is preferably non-reactive with the decolorizing agent. Non-limiting examples of solvents are hydrocarbon

solvents, ethers, and alcohols; preferable hydrocarbon solvents are hexanes, C5-C ₁ 0 alkanes, benzene, toluene, and xylene; preferable ethers are diethyl ether, dibutyl ether, tetrahydrafuran, and dioxin; preferable alcohols are C ₁ -C5 alcohols, most preferably isopropanol. The reaction conditions for combining the resin and the decolorizing agent are not particularly critical. The temperature may be anywhere between -50° to 150°C, preferably -20° to 120°C, more preferably 20° to 110°C, most preferably 40° to 60°C. The pressure at which the claimed process may be conducted is not particularly limited and may be atmospheric, sub- or super-atmospheric. The pressure may be in the range of from about 2 p.s.i. (13.8 kPa) to about 100 p.s.i. (690 kPa), preferably from about 2 p.s.i. (13.8 kPa) to about 50 p.s.i. (345 kPa), more preferably from about 2 p.s.i. (13.8 kPa) to about 20 p.s.i. (138 kPa), most preferably from about 5 p.s.i. (34.5 kPa) to about 10 p.s.i. (69.0 kPa). The process may be conducted in batch, continuous, semi-continuous, slurry, solution, bulk, stirred or tubular reactors and may be performed before or after quenching the polymerized mass (resin) to be treated.

In a preferred embodiment the decolorizing agent is added to a resin solution. The resin solution is a homogenous mixture of polymerization reactants, polymerization reaction products, and unreacted catalyst in solution. The decolorizing agent may be added before or after quenching the polymerization process, preferably before. The solution preferably comprises a solvent that is non- reactive with the decolorizing agent such as but not limited to hydrocarbon solvents, ethers, and alcohols; preferable hydrocarbon solvents are hexanes, C ₅ -C ₁₀ alkanes, benzene, toluene, and xylene; more preferable ethers are diethyl ether, dibutyl ether, tetrahydrafuran, and dioxin; even more preferable alcohols are C -C ₅ alcohols, most preferably isopropanol. Reaction time may be anywhere from about 30 seconds to about 7 days; more preferably from one minute to 24 hours; most preferably from about 5 minutes to 8 hours. The decolorizing agent is typically present in amounts of about 0.01 to about 15 weight percent, more preferably about 0.1 to about 10 weight percent, even more preferably from about 0.5 to 10 weight percent, based upon the weight of the resin. In a preferred embodiment the decolorizing agent is present at least about 0.5 weight percent.

In a preferred example, one would combine a petroleum-based aUphatic resin with 10 weight percent of sodium borohydride or silicon hydride under a nitrogen atmosphere. The reaction mixture would then be allowed to react and preferably be heated to hasten the reaction. The reaction would typically be

aUowed to run for hours if not heated, or minutes if heated then stopped by quenching with a mixture of alcohol (such as isopropyl alcohol or methanol) and water. The treated resin would then be recovered by methods known in the art such as solvent stripping, reprecipitation of the polymerisate with non-solvent and the Uke.

EXAMPLES

EXAMPLE 1

A solution of 50 grams of untreated resin, Escorez® 1310LC (an aUphatic hydrocarbon petroleum resin having a typical softening point of 93°C and a T _g of 46°C available from Exxon Chemical Company, Houston, Texas), was combined with 150 ml of tetrahydrofuran, 10 ml of isopropyl alcohol, 2 ml of distilled water, and 5 grams of NaBH4 (purchased from Aldrich Chemical Co., Inc., Milwaukee, Wisconsin). This slurry reaction mixture was stirred under nitrogen for 24 hours at ambient temperature. The reaction mixture was filtered, then precipitated with excess isopropyl alcohol and methanol. The white powder (treated resin) was filtered by suction and was dried under vacuum at 25°C for 24 hrs. The Gardner color of the starting resin and the treated resin were measured by ASTM D-1544 in a 50 weight percent solution in toluene. The starting resin had a Gardner color of 3.84 while the treated resin had a Gardner color of 2.39. This is a color improvement of approximately 38%.

EXAMPLE 2 (comparative example)

Monomer feed and polymerization of the resin was performed to produce a C5 aliphatic petroleum resin generally consistent with the disclosure of U.S. Patent No. 4,391,961. A reactive mixture of C5 diolefins, a diluent containing paraffins and olefms, benzene, water, and an AICI3 catalyst was prepared as a reactor feed. The reactor was purged with nitrogen and maintained at 50°C. The catalyst was added to the reactor, foUowed by 20 ml of toluene. The reactor was pressurized to approximately 10 p.s.i. (69 kPa). The monomer feed rate was 16.7 g/min. and the total feed addition was approximately 500 g (721 ml) over a period of approximately 30 minutes while stirring the reactor contents. Polymerization was continued for an additional 30 minutes. The reactor was then cooled and vented. 250 ml of the unquenched polymerisate was coUected prior to quenching as the starting material for Example 3 below. The remaining polymerisate was quenched

tO

with a mixture of 300 ml H2O with 100 ml of isopropyl alcohol. The quenched polymerisate was then drained from the reactor for recovery.

EXAMPLE 3 The 250 ml of the unquenched polymerisate from Example 2 was mixed with 24 ml of triethyl silane (TES, 1994-95 Aldrich Catalog no. 23019-7, p. 1387, Milwaukee, Wisconsin). This reaction mixture was stirred under nitrogen for 6 hours at 60°C. The reaction mixture was then quenched by filtering, then precipitating with 150 ml of water and 50 ml of isopropyl alcohol. The white powder was filtered and was dried under vacuum at room temperature for 24 hours.

The Gardner color of the resin of comparative Example 2 and the treated resin product of Example 3 were measured in accordance with ASTM D-1544 in a 50 weight percent solution in toluene. The resin of comparative Example 2 had a Gardner color of 5.91 while the treated resin of Example 3 had a Gardner color of 1.18. This is a color improvement of approximately 80%.

EXAMPLE 4

The procedure as described in Example 1 was used except that 10 g of NaBH4 on a silica support (5% NaBH4 on silica gel, 1994-95 Aldrich Catalog no. 36351-0, p. 1262, Milwaukee, Wisconsin) was used instead of unsupported NaBH4. Gardner color was also measured as in Example 1. The starting resin had a Gardner color of 3.84 while the treated resin had a Gardner color of 3.43. This is a color improvement of approximately 11%.

EXAMPLE 5

A solution of 250 ml of the unquenched polymerisate and solvent of Example 2 was mixed with 15 g of polymer supported borohydride (Amberlyst® A-26, borohydride form, 2 mmol BH4"/g resin). The reaction mixture was stirred (magnetically) at ambient temperature for 24 hours. The reaction products were filtered, quenched with a mixture of 300 ml of isopropanol and 100 ml water, and subsequently washed with 500 ml dilute (1M) hydrochloric acid and then washed twice more with 1 titer of water. The polymerisate was stream stripped at 250°C to recover the final product. The ultra violet (u.v.) absorption intensity of the reaction product was measured using 0.001 g/ml solution in iso-octane. The u.v. absorption intensity maximum at 255 nm of the treated resin was 2.7 while that of

the starting resin was 2.82. This equates approximately to a Gardner color improvement of about 18 percent.

While the present invention has been described and illustrated by reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to variations not necessarily illustrated herein. AdditionaUy, the use of headings and subheadings on paragraphs throughout this document are included as a aid to the reader and should not be construed to limit the scope of the invention in any way.

In the following claims which represent the invention in specific embodiments, each dependent embodiment for each of the below independent embodiments may be practiced with one or more of the limitations of the other dependent embodiments so as to represent other operable embodiments within the scope of the invention claimed.