EMULSIFIABLE RESIN COMPOSITIONS

Abstract: Disclosed are resin compositions which are readily emulsifiable in aqueous media. The compositions are essentially homogeneous blends which consist essentially of, by weight, (1) from about 97% to about 90% resin having a viscosity of from about 100 centipoise to about 8500 centipoise at 57°C. and an acid number of about 5 to about 30, such as an ester of rosin, and (2) from about 3% to about 10% of a non-ionic emulsifying agent. The compositions, which are essentially water-free, are useful in the manufac­ ture of water-borne adhesives.

Description: This invention relates to the chemical art. Particularly, this invention relates to essentially water-'ree resin compositions that are easily and readily emulsifiable in aqueous media, said compositions consisting essentially of a resin having an acid number of from about 5 to about 30 and a nonionic emulsifying agent. U.S. 4,183,834 describes ionizable resinous compositions which are ionized by incorpo-ating into an ionizable resinous mixture a volatile ionizing agent, such as, ammonia. the volatile ionizing agent can be removed from the mixture under conditions effective for volatizing water from a latex adhe- sive formulation. The ionizable resinous mixture used is the reaction product of a rosin, a carboxylic acid and a C1 1;3 monoalcohol. The volatile ionizing agent is added to the resinous mixture to stably disperse the resinous mixture in water and to icnize the resinous mixture prior to the addition of the mixture to a latex. In accordance with this invention there are provided essentially water-free resin compositions which do not require the addition of a volatile ionizing agent prior to addition to a latex. Stable resin dispersions are usually prepared (1) by subjecting an unstable oil-in-water emulsion containing the resin material dissolved in a solvent to high shear by means of a homogenizer, (2) by homogenizing under pressure a preheated, unstable, aqueous dispersion containing the resin material, or (3) by an inversion process wherein water, or water containing a protective colloid and a volatile base, is rapidly added to the molten resin under vigorous agitation. It is highly desirable to have a stable resin composition hich does not require the use of water or high speed mixers or hooogenizers, or both in its preparation, or the addition of a volatile ionizing agent in order to stably disperse the resinous mixture in water prior to the addition of the mixture to a latex. At the same time, the resulting composition should be readily dispersible in water, or in a water-base latex. The resin compositions of this invention are useful in the manufacture of water-borne adhesives, particularly water borne pressure sensitive adhesives. The compositions of this invention are essentially homogeneous blends consisting essentially of, by weight, (1) rom about 97 to about 90 of a resin having a t3roo]f-ie1 viscosity of from shout 10 centipoise to about 8500 centi- poise at 57 C. and an acid number (A.N.) of from about 5 to about 30 and (2) from about 3g to about 10% of a non-icnic emulsifying agent. Preferably the resin compositions will consist essentially of from about 95% to about 93% resin and from about 4% to about 7% of emulsifying agent, and preferably the resin will have an acid number of from about 7 to about 15 and a Brookfield viscosity of from about 100 centipoise to about 7500 centipoise. The compositions are prepared by thoroughly admixing or blending the emulsifying agent and te resin until an essentially homogeneous blend is formed. While blending can be carried out at room temperature (about 23 C), it is advanta- geous to carry out the mixing operation at an elevated tem- perature up to about 100 C., preferably from about 40 C. to about 60 C. for ease of blending. Resins used as component (1) can be an ester of rosin, such as, for example, the methyl ester of rosin; the methyl ester of hydrogenated rosin; the triethylene glycol ester cf rosin; the triethylene glycol ester of hydrogenated rosin; the diethylene glycol ester of rosin; the diethylene glycol ester of hydrogenated rosin; the ethylene glycol ester of rosin and the ethylene glycol ester of hydrogenated rosin, which have a melt viscosity of from about 100 centipoise to about 8500 centipoise at 57 C. and an acid number of trom about 5 to about 30. A blend of two or more resins can be used as component (1), if desired, provided the blend has the properties set forth above for said component (1). Typical resins used in preparing a blend include rosin; esters of rosin; modified rosin; esters of modified rosin; low molecular weight polymers and copolymers of hydrocarbon monomers, such as styrene, alpha-methylstyrene, butene-l, isobutylene, butadiene, isoprene, pentene-l, and monomer mixtures formed by cracking petroleum hydrocarbon mixtures; and polyterpene resins. Suitable rosin esters for forming a blend of two or more resins include the rosin esters above set forth, the glycerol ester of hydrogenated (partially or substantially cornplete3y) rosin, the glycerol ester of rosin, the pentaerythritol ester of hydrogenated (partially or substantially completely) rosin, and pentaerythritol ester of refined rosin. Modified rosins which can be used include hydrogenated (partially or sustan- tially completely) rosin and disproportionated rosin. Suitable polymers and copolymers of hydrocarbon monomers for preparing a blend of two or more resins for use as the resin in the compositions of this invention include alkyl aromatic hydrocarbon resins prepared by polymerizing monomer mixtures formed by cracking petroleum hydrocarbon mixtures; vinyltoluene copolymer resins; low molecular weight styrene and modified styrene resins; and polyterpene resins derived from alpha-pinene, beta-pinene, and monocyclic terpenes such as dipentene. Rosin used to prepare esters of rosin and modified rosins that can be used in this invention can be any of the commercially available types of rosin such as wood rosin, gum rosin, tall oil rosin, and mixtures thereof in their crude or refined state The methyl ester of hydrogenated rosin, the triethylene glycol ester of hydrogenated rosin, the di ethylene glycol ester of hydrogenated rosin, the ethylene glycol ester of hydrogenated rosin, and mixtures thereof with each other or with the glycerol ester of hydrogenated (partially or substantially completely) rosin are preferred for use as resin component (1). Representative resins and resin blends having melt viscosities from about 100 centipoise to about 8500 centipoise at 57"C. and an acid number of from about 5 to about 30 are shown in Table I. TABLE I Resin and Viscosity at Acid Resin Blends 57 C., cps1 Number Methyl ester of 150 7 hydrogenated rosin Triethylene glycol ester 1250 8 of hydrogenated rosin Methyl ester of hydroge- 3550 9 nated rosin (552)/gly- cerol ester of hydroge nated rosin (45%) Triethylene glycol ester 7320 9 of hydrogenated rosin (65%/glycerol ester of hydrogenated rosin (35%) 1. Brookfield Viscosity Typical non-ionic emulsifying agents used to prepare the compositions of this invention are water-soluble compounds represented by the formulas EMI4.1 and R' 0(CH2CH20)nH (11). In formula (I), R is a normal or branched chain alkyl containing from 4 through 18 carbon atoms. Examples of alkyl are butyl, isobutyl, pentyl, neopentyl, hexvl, isohexyl, octyl, nonyl, dodecyl, tetradecyl, hexadecyl and octadecyl. In formula (II), R' is a normal or branched chain alkyl or alkenyl or fused ring cycloalkvl containing from 10 through 20 carbon atoms, examples of which are decal, dodecyl (lauryl), tetradecyl, hexadecyl, oleyl, octadecvl, elcosyl, and abietyl or dihydroabietyl. In formulas (I) and (II), n will have an average value of from about 4 to about 9. Mixtures of two or more of the emulsifying agents can be used if desired. The preferred emulsifying agent is the ethylene oxide adduct of nonylphenol wherein n has an average value of about 4. The following examples are illustrative of this invention. Example 1 The methyl ester of hydrogenated rosin (200 g.) of Table I. is added to a vessel fitted with a means for stirring the contents. Agitation is started and maintained. The contents of the vessel are heated to about 40 C. Surfonic N-95, a nonionic emulsifying agent commercially available from Texaco Inc. comprising the 4 mole ethylene oxide adduct of nonyl- phenol, (10 g.) is then added to the vessel. Stirring is continued until a homogeneous blend is formed (for about 5 minutes to about 15 minutes). Example 2 A homogeneous blend is prepared in accordance with the procedure of Example 1 with the exceptions that triethylene glycol ester of hydrogenated rosin (200 g.) of Table I is used in place of the methyl ester of hydrogenated rosin and the contents of the vessel are heated to about 50"C. Example 3 The methyl ester of hydrogenated rosin (100 g.) of Table I is added to a vessel fitted with a stirrer. Agitation is started and maintained. The contents of te vessel are heated to about 90 C The glycerol ester of hydrogenated rosin (82 g.) of Table I is then added. Then a homogeneous blend of the two resins is formed (after stirring about 5 minutes), the blend, which has an A.N. of about 9, and a Brookfield viscosity of 3550 centipoise at 57 C., is cooled to about 60 C. Surfonic N-95 (9.1 g.) is addrd to the vessel when the temperature of the resin blend ranches out 60 C. Stirring is continued until a homogeneous blend is for (for about 5 minutes to about 15 minutes). Example 4 A homogene un blend is prepared in accordance with the procedure of Example with exceptions that the triethylene glycol ester of hydrogenated rosin (150 g.) of noble I is used in place of the methyl ester of hydrogenated rosin; and the glycerol ester of hydrogenated rosin (80.77 g.), and Surfonic N-95 (11.54 g.) is used. The resin blend has an A.N. of about 9, and a Brookfield viscosity of 7320 centipoise at 57 or The emulsifiable resin compositions of the instant invention are viscous fluids at room temperature (about 23 C), are storage stable, and can be easily and readily handled. Preferably the compositions contain no water. The resin compositions of this invention can be used in combination with a latex to form a water-borne adhesive. Typically from about 30% to about 70% of the emulsifiable resin composition, by dry weight of the latex, is incorporated into the latex. Since the compositions of this invention are readily dispersible in water with mild heat and moderate agitation, it is possible to form an aqueous dispersion thereof either by adding the resin composition to water, or by adding water to the resin composition, to form an aqueous dispersion of from about 40% to about 65% solids, preferably from about 45% to about 60% solids. The preferred method of forming an aqueous dispersion of the resin composition of tis invention is to add the water to the resin composition. The aqueous dispersion thus prepared can then be blended with a late to form a resinous latex adhesive. If desired, the resin comno- sition can be added directly to the latex followed by addition of water to the latex adhesive composition if necessary. Suitable latices include those containing natural rubber and synthetic rubbers or elastomers. Typical synthetic rubbers include styrene-butad ene rubbers (SBR), carboxylated styrene-butadiene rubbers, polyisoprene, acrylonitrilebutadiene rubbers (NBR), polychloroprene (neoprene), polyurethane rubbers (isocyanate), acrylonitrile-butadienestyrene rubbers (ABS), and acrylic rubbers. Alternatively, the latex can be derive from the various vinyl lattices such as, ethylene vinyl-acetate s, ethylene e'.'lylacrylate cop.ly- mers, and the like. Thatices of natural, styrene-butadiene, carboxylated styrene-butadiene, and acrylic rubbers are pre- ferred. Example 5 A resin composition (50 g. ) prepared in accordance with C procedure of E:ample 1 is aided to a vessel fitted ith a means for stirring the contents. Moderate agitation is started 3nd maintained. The vessel is heated until the composition reaches about 400C. Deionized water (50 g.) is then added dropwise to the vessel over a 5 minute period. Stirring is continued until the emulsion is thoroughly mixed. Example 6 The resin composition (82 g.) prepared in accordance with the procedure of Example 1 is added to a vessel fitted with a means for stirring the contents. Moderate agitation is started and maintained. Deionized water (82 g.) heated to about 60 C. is added to the vessel. Stirring is continued until there is provided a stable aqueous emulsion of the resin composition. Example 7 A natural rubber latex (25 g.) is added to a vessel equipped with a means for stirring. Agitation is started and maintained. The resin emulsion (100 g.) prepared in accordance with the procedure of Example 6 is then added to the vessel. Agitation is continued to ensure adequate mixing (for about 10 to about 15 minutes). R latex adhesive having out 50% solids is formed. The resinous latex adhesives are useful as pressure sensitive adheslves, contact adhesives, laminating adhesives, and the like. Typically the solids contents in a pressure sensitive adhesive ranges from about 40% to about 65 solids. It is to be understood that the above description, including examples, is illustrative of the invention and not in limitation thereof.

Claims: 1. An essentially water-free resin composition consist ing essentially of, by weight: (a) from about 97% to about 90% of one or more resins having a melt viscosity from about 100 centipoise to about 8500 centipoise at 570C. and an acid number of from about 5 to about 30; and (b) from about 3% to about 10% of one or more non-ionic emulsifying agents. 2. An essentially water-free resin composition consisting essentially of, by weight: (a) from about 97 to about 90% of an ester of rosin having a melt viscosity from about 100 centipoise to about 8500 centipoise at 57"C. and an acid number of from about 5 to about 30; and (b) from about 390 to about 10% of one or more non-ionic emulsifying agents selected from water-soluble compounds of EMI8.1 and R'-O(CH2C20),1 (11), wherein in formula (I), R is a normal or branched chain alkyl containing from 4 through 18 carbon atoms; wherein in formula (II), R' is a normal or branched chain alkyl or alkenyl or fused ring cycloalkyl containing from 10 through 20 carbon atoms; and wherein in formulas (I) and (it3, n is a whole number. 3. The composition of Claim 2 wherein the resin is the methyl ester of hydrogenated rosin and wherein the emulsifying agent is the formula (I) compound. 4. The composition of Claim 2 wherein the resin is tflc triethylene glycol ester of hydrogenated rosin and wherein t emulsifying agent is the formula (I) compound. 5. The composition of Claim 2 wherein the resin in a blend of: E5'?j of the methyl ester of hydrogenated rosin and 45% of the glycerol ester of hydrogenated rosin, and wherein the emulsifying agent is the formula (I) compound. 6. The composition of Claim 2 wherein the resin is a blend of 65% of the triethylene glycol ester of hydrogenated rosin and 35% of the glycerol ester of hydrogenated rosin, and wherein the emulsifying agent is the formula (I) compound. 7. The composition of Claims 1, 2, 3, 4, 5, or 6 wherein component (a) is present in an amount of from about 96% to about 93%, has a melt viscosity from about 100 centipoise to about 7500 centipoise at 57"C., and an acid number of from about 7 to about 15; and component (b) is present in an amount of from about t to about 7%.

Inventors: ARMSTEAD, JOANN CAROL
Applicants: HERCULES INCORPORATED
Application year: 1983
Main classification: C08L93
IPC codes: B01F17, C08L1, C09J201, C08K5, C08L101, C08L93, C08L33, C09J193, C09J11, C08L51, C08L57, C08L23, C08L27, C08L21, C08L7