MXPA97002319A - Pressure sensitive adhesive for labeling based on styrene-isoprene-styrene rad - Google Patents

Abstract

A hot melt adhesive composition comprising about 5 to 15% by weight at least one styrene-isoprene-styrene block copolymer having the general configuration (pS-pI-pB) nX where n is a greater number than 2, the block copolymer has a molecular weight of about 90,000 to 380,000 and preferably about 100,000 to 250,000 and an approximate styrene content of 15 to 35% by weight, and preferably 20 to 30% by weight, up to 10% of a compatible polymer, wherein the total content of the polymer does not exceed 15% from about 30 to 60% by weight of at least one binder or compatible binder resin, from about 20 to 40% by weight of at least one compatible plasticizer, and from about 0.1 to 2% by weight of a stabilized

Description

PRESSURE SENSITIVE ADHESIVE FOR LABELING BASED ON STYRENE - ISOPRENE - RADIAL STYRENE DESCRIPTION OF THE INVENTION This invention relates to a hot melt adhesive composition comprising a novel styrene-isoprene-styrene radial block copolymer which is useful as a labeling adhesive, especially in the area of labeling bottles. Hot melt sensitive compositions are widely used in the adhesives industry due to their ability to adhere a wide variety of substrates, block copolymers are a preferred base due to their good heat stability, high adhesive strength, elastomeric properties, and Compatibility with a wide range of plasticizers and adherents. A primary property of hot melt pressure sensitive composition is that it remains adherent at room temperature and can adhere to substrates when completely cooled from its molten state. The applications that require this property include labeling. Paper, polyethylene, polypropylene, polystyrene, composites or laminates or other substrates can be covered with that hot melt pressure sensitive adhesive, which is then covered with a removable layer, and sent for subsequent application of the labels to substrates such as different containers books, magazines, corrugated boxes, and envelopes to name a few. In addition to the types of labeling mentioned, there is also the labeling of bottles and containers where the hot melt adhesive is applied to the bottle or container itself, and the label is stuck to that bottle or container in the line of work. The labels are not precoated and are shipped as stated in the examples. The most widely used materials for bottles or containers include, but are not limited to, glass, polyethylene, polyethylene terephthalate or PET, polyethylene, polypropylene, polyvinyl chloride ( PVC). Such materials are generally difficult to join, and the use of block copolymers as an adhesive base facilitates bonding. Hot melts for bottle labeling are characterized by low viscosities and long opening times. Low viscosities are required because of the types of equipment used to label bottles and the restrictions that this equipment imposes. The equipment operates at high speeds and can form threads if the viscosities are very high. The speeds in the line can be 1000 bottles per minute. These adhesives are also characterized by having good cold temperature flexibility, and excellent adhesion to a wide variety of substrates. These two properties are required because the bottles are frequently for beverages, and they are filled in the line before being labeled. These containers frequently they are cold and wet, which puts more demands on the adhesive. The expansion of the bottle that is presented by the filling requires that the adhesive has good flexibility. In addition these adhesives require good resistance to heat to be sent and stored in the summer months. Temperatures in transport vehicles can exceed 50 °. It can be difficult to achieve high heat resistance while maintaining good cold temperature flexibility, long opening times, and low viscosities because these characteristics are opposed to each other. A recent trend for the labeling manufacturer for bottles is to reduce costs by using substrates of a lower thickness. These substrates are frequently polyethylene, polypropylene or composites of such materials that are sensitive to heat. As the thickness of the film decreases, the film becomes more sensitive to heat, the application temperatures must be lowered, and the optimum temperatures are between 120 and 150 °. Conventional hot melt adhesives are applied at temperatures of approx. 155 to 175". The viscosities of these conventional adhesives would be optimal at temperatures above 155 °. These hot melts can therefore not be applied at temperatures below about 150 ° without machining difficulties such as adhesive spinning and Nozzle clogging When temperatures drop, it is also more difficult to obtain good adhesion to difficult substrates. It is therefore a breakthrough in the art to offer hot melt adhesives that can be applied at lower temperatures while maintaining the characteristics of conventional adhesives such as good adhesion and high heat resistance .. US Patent 5,292,819 issued to Diehl on 8 March 1994, presents the use of a styrene-isoprene-styrene radial block copolymer (S-IS) having the general configuration (pS-pl-pB) nX where n is a number greater than 2 for use in several applications of hot melt as for disposable items. However Diehl does not teach the use of such polymers in hot melt adhesives for labeling applications. Diehl's formulations can in fact not be used for labeling applications because of the viscosity restrictions when hot melt labeling, the formulations of this invention have high polymer contents and their viscosity is too high. U.S. Patent 5, 399, 627 to Diehl given March 21, 1995 discloses the use of radial SIS block copolymer having the general configuration (pS-pl-pB) nX wherein n is greater than 2, for use in hot melt adhesives. The physical characteristics for a hot melt tape adhesive are widely different from the characteristics of a hot melt label adhesive. Diehl presents adhesives that would have too much viscosity for applications at temperatures of approx. 120 to 150 °. These adhesives also have a too high viscosity for the high speeds of the labeling equipment. Similarly, US Pat. No. 4,411,954 to Butch, issued October 25, 1983, discloses a pressure-sensitive hot melt adhesive based on styrene-isoprene-styrene for diaper closures, these adhesives would also have too much viscosity to be able to used in the high-speed labeling equipment. the viscosities of this invention are shown as greater than 6000 cPs at 163 ° in contrast to the adhesives of the present invention having lower viscosities of ca. 3000cPs at 120 °. U.S. Patent 5,057, 571 to Malcolm given on October 15, 1991, discloses the use of a radial block copolymer having the general configuration (AB) nl-Y- (B) n2 where block A comprises styrene and the block B butadiene, isoprene or mixtures thereof for the construction of disposable articles. Malcolm does not show the use of those products for labeling applications. their hot melt compositions would have too high a viscosity for labeling. The Malcolm adhesive compositions have a viscosity of 6,000cPs at 135 ° in contrast to the compositions of the present invention with less than 3000cPS at 120 °. Therefore Malcolm compositions can not be used in applications where the requirements are very low viscosities such as to label bottles. US Pat. No. 4,619,851 to Sasaki, issued October 28, 1986, teaches the use of a combination of oplastic rubber and aliphatic hydrocarbon resin to achieve a slight compatibility of the hot melt adhesive to improve the cutting of the labels. The rubber content of the adhesive improves die cutting of the labels. The rubber content of that invention is greater than that of the present invention. The products would have too high a viscosity to be used in high speed labeling equipment. The US patent to Flanagan given on July 31, 1990 discloses hot melt pressure sensitive adhesive compositions for use in making liners for the binding of books. This invention uses a styrene-butadiene-styrene block copolymer with a styrene content greater than about 35%. This invention does not present the use of those products for labeling. These products have high tensile strengths and high modulus which is advantageous for the linings but disadvantageous for the labels. Furthermore, these products do not achieve high adhesive properties useful for permanent labeling as in the present invention. The American patent 4, 714,749 to Hughes given on December 22, 1987 discloses the use of a fully saturated petroleum resin in combination with a saturated block thermoplastic elastomer such as Kraton G, which is a saturated block copolymer having butadiene-ethylene as the central block in contrast to the base polymers of the present invention containing isoprene in the middle block. These adhesives are oil-free systems, and contain saturated middle block elastomers in concentrations greater than approx. 35% by weight of the total adhesive, in contrast to the present invention having a content of 5 to 15% by weight. Hughes does not teach how to make adhesives with low polymer content. Their compositions would have a too high viscosity and not useful for the applications of the present invention. US Patent 4, 460, 364 to Chen given July 17, 1984 teaches the use of rubber block copolymers as a base for removable pressure sensitive adhesives for medical devices. The removable PSA is asked about such products as band aids, labels, and calico liners. The PSA is then covered with a removable liner to allow transportation and storage of the finished product. When the finished product is used, the liner is removed, the product is put on the desired surface (person, clothes, machine, item) and the hand pressure is applied to adhere two substrates together. The adhesive both binds to the ambient temperature without heat, This is not a permanent bond, and when removing the label, band, liner etc. it is desired that no residue remains on the surface where it was. The desirable characteristics of PSA removable, include a soon aggressive glue, which is the ability to immediately adhere to a substrate, lack of surface residue, and poor adhesion when peeling. The adhesives of the present invention in contrast have a permanent degree of Glue is used to permanently bond two substrates, instead of forming a temporary bond. They are used to join two substrates using application temperatures greater than 120 ° but less than 150 °. instead of ambient temperatures. The Chen compositions have high block copolymer contents greater than 18% and the viscosities would be too high for the high speed labeling equipment. Chen adhesives would be applied using such methods as die cut or spray coating. U.S. Patent 4,136,699 to Collins, issued Jan. 30, 1979 discloses a disposable article for absorbing fluids having a hot melt adhesive containing approximately 10 to 20% by weight of a radial block copolymer having a general configuration A_B_A, where A is polystyrene, and B is essentially poly (mono-olefin). An example of the middle block would be ethylene-butadiene. These adhesives are also removable PSA. But the present invention has as B isoprene and the adhesive has a permanent PSA grade.

U.S. Patent 5, 360,854 to Bozich given Nov. 1, 1994, discloses a hot melt pressure sensitive adhesive based on styrene-butadiene-styrene block copolymers, such adhesives have high contents of block copolymer. In addition, the block copolymer of Bozich contains styrene in 35 to 55% by weight of the block copolymer. The high percentages of styrene result in hard block copolymer difficult to paste. These adhesives are also oil free and have a high viscosity. They could not be used in the applications to which the present invention is directed. The present invention has found that using low amounts of block copolymers S-I_-S having the general configuration (pS-pl-pB) nX or (pS-pI) nX as the base polymer for hot melt pressure sensitive adhesives It allows low viscosity adhesives to be applied at temperatures of approximately 120 to 150 ° C, but maintaining excellent glue or adhesion, flexibility, cohesive strength and heat resistance. The present invention features a hot melt pressure sensitive adhesive comprising a) from about 5 to 15% of at least one styrene-isoprene-styrene-radial block copolymer having the general configuration (pS-pI-pB) nX or (pS-pI) nX wherein n is greater than 2, the block copolymer has an average molecular weight of from about 90,000 to 380,000 and preferably from 100,000 to 250,000 and a styrene content between 15 and 35% by weight of the copolymer in block, and preferably from 5 to 10% by weight of at least one radial block copolymer; b) up to about 10% by weight of a compatible polymer wherein the total content of the polymer does not exceed 10%; c) from about 30 to 60% by weight of at least one compatible tackifying resin; d) from about 20 to 40% by weight of at least one compatible plasticizer; and e) from about 0.1% to 2% by weight of stabilizer. The mixing of the individual components results in a compatible mixture. This indicates a lack of phase separation of the individual components. The resulting hot melt or hot melt pressure sensitive adhesive is characterized by viscosities less than about 3,000c Ps at about 120 ° and preferably less than 2000c Ps at 120 °; and tear adhesion failure temperatures greater than 50 ° and more preferably greater than approximately 55 °. The adhesives of the present invention maintain excellent adhesion, cold temperature flexibility, heat resistance, and cohesive strength while maintaining very low viscosities compared to similar formulations with block copolymers. These adhesives have excellent adhesion to difficult substrates including but not limited to PET, glass, polystyrene, polyethylene, polypropylene, and laminates or composites. These adhesives can be applied at temperatures between about 120 and 150 ° C. In contrast to the prior art these polymers are useful in amounts less than about 15% of the weight of the total adhesive formula. The resulting adhesives have very low viscosities, and therefore can be applied at temperatures between 120 and 150 °. In fact, the hot melt pressure sensitive adhesives of the prior art can not be used in the field of labels where the equipment used requires very low viscosities. Nor can they be used in thin films because of the distortion that occurs with the high temperatures required to apply conventional hot melt adhesives. It is therefore a breakthrough in the art to provide a hot melt pressure sensitive adhesive that imparts excellent adhesion, high heat resistance, and very low viscosity, allowing all of the above to be applied at low temperatures compared to the previous technique. These adhesives can be used in all kinds of applications where pressure sensitive adhesives can be used, and specifically in the labeling field. These adhesives are especially useful for labeling bottles where very low viscosities are required. The radial block copolymers useful in the present invention are those having the general configuration (pS-pI-pB) nX op (pS-spI) nX where pS is polystyrene, pl is polyisoprene, pB is polybutadiene, X is a residue of a multifunctional coupling agent used in the production of radial block copolymer, and n is a number greater than 2 representing the number of branches attached to X, which are also referred to as arms. The number of branches is preferably 3 to 5, more preferably 4. It is difficult to obtain a radial block copolymer, however this has as its composition only molecules with 4 branches. Some molecules with 3 branches and some molecules with 5 branches may be present It is also possible that molecules are present that have different branches in number 3, 4 and 5. It is preferable that the radial block copolymer contains more than 60% of 4-branch molecules. The number average molecular weight is from about 90,000 to 380,000 and preferably from 100,000 to 250,000. Although a preferred molecular weight range is specified to maintain low viscosities, it is known to the artisan that a lower amount of a higher molecular weight polymer it can be used to achieve the same viscosity margin. The styrene content is from about 15 to 35% of the copolymer in radial block, and preferably from 20 to 305. It is preferable to keep the styrene content in this range to obtain optimum flexibility. The coupling efficiencies of these polymers is greater than about 60% and preferably 70%. Coupling efficiency refers to the amount of triblock present versus diblock in the block copolymer. Coupling efficiency is important to achieve high heat resistance. The lower the coupling efficiency, the higher the diblock and softer content. the polymer which can result in low heat resistance. Useful polymers include DPX-550, DPX 551, and DPX 552 obtainable from Dexco Polymers in Houston Texas; Kraton (M.R) D-1124 obtainable from Shell Chemical Co in Houston Texas; Quintac (M.R.) SH-108 and Quintac 3450 obtainable from Nippon Zeon in Tokyo, Japan. all are styrene-isoprene-styrene radial polymers. These polymers are useful from about 5 to 15% by weight and preferably from 5 to 10% by weight. Useful adhesive resins may include aliphatic, cycloaliphatic and aromatic hydrocarbon resins and hydrogenated derivatives; and mixtures thereof; rosins and rosin derivatives, and modified soils and lands, and mixtures thereof. Adherent resins have a Ring and Ball softening point (ring and ball) of between 70 and 150 ° C. The technician will recognize that those tackifying resins are obtainable with different levels of hydrogenation. Useful resins include Eastotac (M.R.) H-100 and H-130 from Eastman Chemical Company which are partially hydrogenated cycloaliphatic peeum hydrocarbon resin with different softening points; Escorez (mR) 5300 and Escorez 5400, peeum hydrocarbon resins and Escorez 5600, a partially hydrogenated aromatic modified peeum hydrocarbon resin, all obtainable from Exxon Chemical Company, Wingtack Extra which is an aromatic peeum hydrocarbon resin, aliphatic obtainable from Goodyear Chemicals; Hercolite (M.R.) 2100 which is a partially hydrogenated cycloaliphatic peeum hydrocarbon resin obtainable from Hercules; Zonatac (M.R.) 105 Lite which is an esterinated hydrocarbon terpene resin made from d-limonene and obtainable from Arizona Chemical; Sylvatac (MR) 1103 obtainable from Arizona Chemical, Unitac (MR) R-100 Light obtainable from Union Camp and Permalyn 305 obtainable from Hercules, which are rosin esters of pentaerythritol.These glues are useful in the range of about 30 to 60% by weight in the adhesive. Useful compatible polymers may include triblock copolymers A-B-A and diblock polymers A-B, multiblock copolymer A-B-A-B-A-B, and radial block copolymers, and grafted versions thereof; homopolymers, copolymers and ethylene terpolymers, and propylene block copolymers having the general configuration A-B-A, with end blocks of styrene and ethylene-butadiene middle blocks described in the patent to collins and associated U.S. No. 4,136,699, which would be useful in amounts less than about 5% by weight in the adhesive. These polymers are obtainable under the trademark Kraton G from Shell Chemical Co, located in Houston Texas. The technician knows that there are several grades of Kraton G. Some examples include products under the trademarks Kraton G-1726, Kraton G-1657, Kraton G-1652 and Kraton G-1650, diblock AB saturated with ABA triblock mixture with medium blocks of ethylene-butadiene, Kraton D-1112, a styrene-isoprene-styrene polymer with a high percentage of AB diblock; Kraton D-1107 and Kraton D-llll, triblock linear styrene-isoprene-styrene polymers firstly A-B-A; Stereon s 840A and Stereon 841 A, (registered trademarks) which are a styrene-butadine-styrene polymer of multiblock ABABAB obtainable from firestone located in Akron Ohio Europrene Sol T 193 B (MR) a styrene-isoprene-styrene polymer obtainable from Enichem Elastomers in New York; Europrene Sol T 163 a styrene-butadiene-styrene polymer also obtainable from Enichem Elastomers; Vertor 4461-D a linear styrene-butadiene-styrene polymer obtainable from Exxon Chemical Co. in Houston Texas Vector 4111.4211 and 4411, linearly coupled polymers styrene-isoprene-styrene containing different weight percentages of the styrene end block; Vector 4113 a linearly coupled styrene-isoprene-styrene polymer also obtainable from Exxon Chemical Co. other polymers such as homopolymers Copolymers and terpolymers of ethylene and polypropylene may be useful in amounts of less than about 5% by weight in the adhesive. Some examples include ethylene vinyl acetate copolymers such as Elvax 410 and Elvax 210 brands of Dupont Chemical Co. located in Wilmington D E; Escorene UL 7505 obtainable from Exxon Chemical Co. ultrathene UE 64904 obtainable from Quantum Chemical Co. in Rolling Meadows ILL; and AT 1850M obtainable from AT Polymers & Film Co. in Charlóte NC. Other useful polymers include Exact 5008, an ethylene-butene polymer; Exxpol SLP- 0394 ethylene-propylene polymer; Exact 3031, an ethylene-hexene polymer all obtainable from Exxon Chemical Co; and Insight SM-8400 an ethylene-obtene polymer obtainable from Dow Chemical Co. located in Midland MI. These compatible polymers are useful up to about 10% by weight. A minimum amount of plasticizer is necessary for the present invention. Plasticizers may include oil, liquid resins, liquid elastomers, or any other material that flows at room temperature and is compatible with the block copolymer. A plasticizer is defined in general terms as a typically organic composition that can be added to thermoplastics, rubber and other resins to improve extrudability, flexibility, workability and stretchability. The plasticizers used herein may include mineral hydrocarbon oils or polybutene oil liquid elastomeric liquid adherent resins or functionalized oils such as glyceryl trihydroxyoleate or other fatty oils. The oils are mainly hydrocarbon oils, with low aromatic content and paraffin or nastenic character. The oils have low volatility are transparent and as little color and odor as possible this invention also contemplates the use of orefin oligomers, low molecular weight polymers, vegetable oils and their derivatives and similar plasticizing liquids. These plasticizers are useful in approximate amounts of 20% to 40% by weight Examples of useful plasticizers include Calsol 5120, an oil-based naphthenic oil obtainable from Calumet Lubricants Co in Indianapolis In. Kaydol White Mineral Oil a paraffin mineral oil obtainable from Wittco Corp in New York NY; Parapol 1300, a liquid butene homopolymer obtainable from Exxon Chemical Co in Houston Texas; Indopol H-300 a butene liquid homopolymer obtainable from Amoco Corp in Chicago 111; Escorez 2520 a liquid aromatic petroleum based petroleum resin with a pour point of 20 °, obtainable from Exxon Chemical Co .; Regalrez 1018 a liquid hydrogenated aromatic hydrocarbon resin with a pour point of 18 ° obtainable from Hercules in Chicago 111; and Sylvatac 5N a modified rosin rosin resin with a pour point of 5 ° obtainable from Arizona Chemical Co in Panama City Fl. The technician will recognize that any secondary naphthenic process oil 500 or 1200 could be used.

A stabilizer or antioxidant can also be used in hot melt adhesives. These compounds are added to protect the adhesive from degradation caused by reaction with oxygen induced by such things as heat, light or residual catalyst from raw materials such as adhesive resin. Such antioxidants are commercially available from Ciba-Geigy and include Irganox 1010 and Irganox 1076 which are hindered phenols. These are primary antioxidants that act as radical scavengers and can be used alone or in combination with other antioxidants such as phosphite antioxidants such as Irgafos 168 obtainable from Ciba-Geigy. Phosphite catalysts are considered secondary catalysts and are generally not used alone , They are mainly used as decomposers. Other obtainable catalysts are Cyanox LTDP obtainable from American Cyanamide, and Ethanox 1330 obtainable from Albe arle.Much of such antioxidants are obtainable either alone or in combination with other such antioxidants. These compounds are added to the hot melts in small amounts that can be added and that also do not affect the physical properties are pigments that give color, or fluorescent agents, to mention a few. Additives such as these are known to the technicians, the adhesive of the present invention is useful for labeling, including labeling bottles, and other applications.

The adhesives of the present invention are characterized by excellent heat resistance, cold temperature flexibility and bonding, as well as low viscosities. Low viscosities are required for the application of labels with high speed, and where the equipment prevents the use of material with high viscosity. If the adhesive has too high a viscosity for a particular application, there is poor machining of the adhesive with the formation of yarns, and clogging of the nozzle. the adhesives of the present invention have viscosities less than about 3000cPs at 120 ° C. Low viscosities also allow application at lower temperatures. A standard application temperature is greater than about 150 °. The adhesives of the present invention can be applied at temperatures greater than about 120 °. The recent trend in the labeling industry has been to use thin films to save costs, thin films are more easily distorted by heat and therefore require lower application temperatures. Heat resistance is required for transport and storage in the summer months. Heat resistance can be measured by the temperature of failure of adhesion by tearing (Shear Adhesion Failure Temperature or SAFT). The adhesives of the present invention are characterized by a SAFT greater than about 50 ° or preferably greater than 55 °. Cold flexibility at the temperature is needed for transport and storage in the winter months. It is necessary to label the bottles that the bottles are filled with cold drinks, and the conditions of the plant can be cold with great amount of condensation. The flexibility at cold temperature can be characterized by the glass transition temperature or Tg. The adhesives of the present invention have Tg values comparable to the prior art adhesives, but have superior heat resistance than those of the prior art. This is a desirable feature. The invention will be illustrated by the following non-limiting examples. Examples 1-3 and Comparative Examples AI and KP Test Methods 1.-Melt viscosities The melt viscosities of the hot melt adhesives were determined in a Brookfield viscometer thermosel model DVI using a spindle number 21. 2.-Temperature of Tear Adhesion Failure (SAFT) The adhesive is sneaked from a solvent mixture as a 1 ml film using a Baker applicator on a 2 mil Mylar MR thick polyester The adhesive / solvent ratio is 1: 1. the adhesive film is allowed to dry. A removable liner is placed over the top of the film and 4 square inches of approximately 25 square centimeters of the film are cut out. An area of 1 x 4 inches (2.5 x 10 cm) is marked and the mylar film is placed on top of this . This is then cut into four samples, each having an area of lxl inches (2.5x 2.5 cm). They are allowed to stand for 12 hours and then put in a programmed oven with a weight of 500 g using a tear mode. The oven starts at 25 ° and increase 25 degrees per hour for three hours. The oven automatically registers the temperature at which the sample fails cohesively. 3.- Adhesion of 180 ° peel to stainless steel Peel values were determined using a PSTC-1 test method. Approximately one lmil adhesive film is coated on the polyester (Mylar) from a solvent mixture using a Baker applicator. The samples are cut into strips of 1 x 8 inches (2.5 x 20 cm) to determine the values of peeling. 4.-Loop glue test. An approximately 1 mil adhesive film was placed on a polyester (Mylar) from a solvent mixture using a Baker applicator. It was left to dry for a minimum of 24 hours.Then the film was coupled with a removable liner and cut into strips of lx 5 inches (2.5 x 12.5 cm) A test sample or test was inserted inside a loop glue tester of Chemsultants International with the adhesive side facing outward (removing the liner). The loop glue tester automatically records the adhesive value or glue in ounces per square inch. 5.-Rheological measurement of polymer melts using dynamic mechanical procedures. Rheological data were determined using the method of ASTM D4440-84. A standard step test was used in comparison to the continuous increase in temperature, the resting or dwell time was 2.5 minutes before each temperature increase. The frequency of 10 radians per second. 6. - Cast Garden Color ASTM Method D 1544 was used to measure the cast garden color with a Gardner Delta IIluminator and a Gardner Delta Comparator made by the Pacific Scientific Gardner Laboratory Division in Bethesda Maryland. The adhesives of the present invention are characterized by viscosities of less than 3000c Psa about 175 °, SAFT values greater than about 50 ° and preferably greater than 55 ° and Tg values less than about 20 °, and preferably less than 10 °. The adhesive examples of the invention are also clear and essentially colorless having Molten Gardner colors less than 3. This is advantageous when the labels are also clear. The user of the adhesive would prefer adhesives that can not be seen through the label. For applications in which color is not an important factor other raw materials such as different glues can be used which would give a cast garden color (Molten Gardner color) higher. The samples of adhesives were prepared by first making a premix of rubber to glue in the ratio 1: 1. This was prepared in a high tear sigma sheet mixer manufactured by littleford day located in FLORENCE KY. The premix is then slowly added to approximately 60 grams of pedant resin using a single blade mixer heated to approximately 175 °. sheet can also be designated as stand-by mixers. The challenge of the components including what is missing from the pedant resinif there is something, they are added slowly and the resulting mixture is stirred until it is homogeneous. EXAMPLE 1 AND COMPARATIVE EXAMPLES AI This example illustrates the superior heat resistance that can be obtained using the radial styrene-isoprene-styrene polymer of the invention while maintaining a low viscosity profile, as compared to conventional block polymers. The test adhesives have been formulated with a polymer level of 10% by weight in the adhesive. The heat resistance is measured using a tear adhesion failure temperature (SAFT) test. Comparative example I has a viscosity that it is much higher than any of the other examples as indicated in table 1.

TABLE 1 EXAMPLE 2 AND COMPARATIVE EXAMPLES KN Example 2 also shows the high heat resistance that can be achieved using a styrene-isoprene-styrene radial polymer of the invention compared to conventional block polymers, but maintaining a low viscosity profile. polymer. for all formulations it was 10% by weight in the adhesive.

TABLE 2 EXAMPLE 3 AND COMPARATIVE EXAMPLES O and P The following example illustrates the high heat resistance that can be obtained by a low percent by weight of the styrene-isoprene-styrene radial polymer compared to using a higher percentage by weight of a styrene-polymer. linear butadiene-styrene or a styrene-ethylene-butadiene-styrene polymer. A lower viscosity is obtained by using smaller amounts of the styrene-isoprene-styrene polymer and superior heat resistance can be achieved.

TABLE 3 used. Irganox 1010, Irganox 1076 and Irganox 565 which are registered trademarks were used in the previous examples. These ingredients are not essential for the performance characteristics of these examples. EXAMPLE 4 AND COMPARATIVE EXAMPLES O & P The following examples use rheological measurements to illustrate the highest heat resistance achieved with a lower percentage of radial compound SIS (styrene-isopropene-styrene) compared to a linear SBS (styrene-butadiene-styrene) and an SEBS ( styrene-ethylene-butadiene-styrene) linear.The glass transition temperature illustrates the flexibility at cold temperature that is maintained with radial SIS, while the softening point illustrates the superior resistance to heating obtained with a lower polymer charge in comparison to SBS and linear SEBS. The higher heat resistance that is achievable with the radial SIS is made more remarkable by the fact that Example 4 contains a higher level of plasticizer than the comparative examples O and P, which typically decreases the resistance to heat.

TABLE 4 Note: Any antioxidant known to the technician can be used Irganox 1010, Irganox 1076 and Irganox 565 (registered trademarks) were used in the previous examples. These ingredients are not essential for the performance characteristics of these examples.

Claims (10)

1. A hot melt adhesive composition comprising: a) from about 5% to 15% by weight of the adhesive and preferably from about 5% to 10% of the adhesive of at least one styrene-isoprene-styrene block copolymer , having the general configuration (pS-pI-pB) nX or (pS-pI) nX, where n is a number greater than 2, the block copolymer has a molecular weight of approximately 90,000 to 380,000 and a content of styrene approximate 15% to 35% by weight of the polymer; b) from about 0% to 10% by weight of the adhesive of a compatible polymer; c) from about 30% to 60% by weight of the adhesive of at least one compatible adherent or pedaling resin; d) from about 20 to 40% by weight of the adhesive of at least one compatible plasticizer; e) from about 0.1% to 2% by weight of the adhesive of a stabilizer, wherein the total content of the polymer does not exceed 15% by weight of the adhesive, and the resulting viscosity is less than about 3,000 cPs, at a temperature of approximately 120 °.

2. A hot melt adhesive composition useful for labeling, comprising: a) from about 5% to 15% by weight and preferably from 5 to 10% by weight of the adhesive of at least one copolymer of radial block, having the general configuration (pS-pI-pB) nX or (pS-pI) nX, where n, is a number greater than 2, the block copolymer has an average molecular weight of from about 90,000 to 380,000 and preferably from 100,000 to 250,000, and an approximate styrene content of 15 to 35%, and preferably 20 to 30% by weight in the copolymer; b) from about 0% to 10% by weight of the adhesive of a compatible polymer; c) from about 30% to 60% by weight of the adhesive of at least one compatible pedant resin; d) from about 20 to 40% by weight of the adhesive of at least one compatible plasticizer; and e) from about 0.1% to 2% by weight of the adhesive of a stabilizer, wherein the total content of the polymer does not exceed 15% by weight of the adhesive.

3. Adhesive according to claim 1, wherein the radial block copolymer has a coupling efficiency greater than about 60%, and preferably greater than 70%.

4. Adhesive according to claims 1, 2, wherein the compatible pedant resin is selected from the group consisting of aliphatic, cycloaliphatic and aromatic hydrocarbons and hydrogenated derivatives, modified soils and terrains, rosins and rosin derivative, as well as mixtures thereof. same.

5. Adhesive according to claims 1, 2, wherein the compatible pedant resin has a color Molten Gardner Color, less than about 3, and preferably less than about 2.

6. Adhesive according to claims 1, 2, wherein the Pedantic compatible resin is at least partially hydrogenated.

7. Adhesive according to claims 1, 2, 3, 5, wherein the compatible polymer is thermoplastic.

8. Adhesive according to claims 1, 2, wherein the compatible plasticizer is selected from the group consisting of naphthenic paraffinic acid, polybutene, liquid elastomers, liquid adhesives, and mixtures thereof.

9. Adhesive according to claims 1, 2, wherein the resulting tear adhesion failure temperature is greater than 50 ° and preferably greater than approximately 55 °.

10. Adhesive according to claims 1, 2, wherein the adhesive comprises a mixture of less than about 10% by weight of the adhesive, of a radial block copolymer having the general configuration (pS-pI-pB) nX or ( pS-pI) nX, where n, is a number greater than 2, the block copolymer having an average molecular weight of about 100,000 to 250,000, a styrene content of about 20% to 30% by weight of the polymer and an efficiency coupling greater than 70%; a compatible block copolymer selected from the group consisting of an AB diblock, a ABABAB multiblock, an ABA triblock, a radial block and grafted versions thereof, a compatible pedant resin selected from the group consisting of aliphatic, cycloaliphatic and aromatic hydrocarbons and hydrogenated derivatives, and mixtures thereof, the pedant resin having a ring and ball softening point of approximately 70 to 150 °, a compatible plasticizer selected from the group consisting of naphthenic and paraffinic oil; and a stabilizer wherein the total content of the polymer does not exceed 15% by weight of the adhesive. RES UM EN A hot-melt adhesive composition comprising about 5 to 15% by weight of at least one styrene-isoprene-styrene block copolymer having the general configuration (pS-pI-pB) nX where n is a number greater than 2, the block copolymer has a molecular weight of about 90,000 to 380,000 and preferably about 100,000 to 250,000 and an approximate styrene content of 15 to 35% by weight, and preferably 20 to 30% by weight, up to 10% of a compatible polymer, wherein the total polymer content does not exceed 15% from about 30 to 60% by weight of at least one compatible binder or pedaling resin; about 20 to 40% by weight of at least one compatible plasticizer, and about 0.1 to 2% by weight of a stabilizer.