KR100885931B1 - Rubber-acrylic adhesive formulation - Google Patents

Abstract

The present invention relates to pressure sensitive adhesive formulations of hydrogenated rubber and grafted acrylic polymers. In one embodiment, the polymer comprises hydroxyalkyl (meth) acrylate esters crosslinked with titanium containing chelated metal alkoxides. The adhesive formulations have excellent adhesion to low energy surfaces and cohesive strength at high temperatures.

Pressure Sensitive Adhesive, Acrylic Polymer, Macromer, Graft, Adhesive Strength, Cohesive Strength

Description

Rubber-Acrylic Adhesives {RUBBER-ACRYLIC ADHESIVE FORMULATION}

The present invention relates to pressure sensitive adhesives. In particular, the present invention relates to pressure sensitive adhesives comprising acrylic polymers grafted with ethylene-butylene rubber macromers.

A typical acrylic pressure-sensitive adhesive is a copolymer of an alkyl ester monomer or a functional monomer such as acrylic acid, and can be crosslinked using, for example, aluminum chelate. Typically, such acrylic pressure sensitive adhesives have insufficient adhesion to low energy surfaces. Accordingly, in order to improve adhesion of the pressure-sensitive adhesive to the low-energy surface, the rosin ester may be used to provide adhesion, but there is a problem in that heat resistance may be lost and aging characteristics may be poor. Although the aging properties of the adhesive may be impaired by imparting tackiness, such tackified acrylic dispersions serve several applications, for example most paper label applications, and in fact are paper It has taken an important place in label technology. However, the acrylic adhesives imparted with the above adhesives do not have sufficient degradation resistance for application to most graphic and industrial tape applications that have previously used acrylic solutions.                 

Often, rubber-resin formulations are used to adhere to polyolefins and other low energy substrates. Typical compositions of the formulations consist of natural rubber or styrene block copolymers imparted with tackiness using rosin esters. The formulation can provide excellent adhesion and cohesive strength, but may discolor and lose tack upon aging due to oxidative degradation and degradation by UV light induction. In addition, totally hydrogenated rubber and resin formulations are more expensive and do not typically have the required adhesion performance.

U. S. Patent No. 5,625, 005 describes hybrid rubber-acrylic pressure sensitive adhesives as adhesives having high adhesion to nonpolar surfaces, good UV resistance and aging properties. Even in the prior art with such an improvement, a pressure reduction having sufficient adhesion and chemical resistance for applications such as industrial tapes and transfer films, and applications such as outdoor graphics on low-energy surfaces that are difficult to bond surfaces to There is a need for polymer compositions of improved physical properties that can be used to prepare adhesives. The present invention has been made in view of such circumstances.

The present invention provides an adhesive that has excellent coating properties and adhesion to a variety of substrates, including low energy surfaces, and can maintain the above-mentioned properties at high temperatures in a dry state.

One aspect of the present invention provides a pressure-sensitive adhesive comprising a rubber macromer and a grafted acrylic polymer. In the present invention, it is preferable to use an ethylene-butylene macromer as the macromer. In one embodiment, the acrylic polymer comprises at least one alkyl acrylate monomer having an alkyl group of about 4 to about 18 carbon atoms and having a low glass transition temperature (Tg), and a high glass transition temperature (ie, having a Tg of about At least one monomer (greater than 0 ° C.). As a preferred embodiment of the present invention, the acrylic polymer may further include at least one hydroxyl group functional monomer and / or may further include at least one carboxyl functional monomer. As a particularly preferred embodiment, crosslinkers such as aluminum or titanium crosslinkers are used.

Another aspect of the invention is an acrylic polymer comprising at least one alkyl acrylate monomer having a low Tg and having an alkyl group of about 4 to about 18 carbons grafted with a rubber macromer, preferably an ethylene-butylene macromer. To include, the polymer provides a pressure-sensitive adhesive crosslinked with a titanium crosslinking agent. In a preferred embodiment, the acrylic polymer includes at least one monomer having a high Tg, at least one hydroxyl group functional monomer and / or at least one carboxyl functional monomer in addition to the alkyl acrylate monomer. And when using the titanium containing metal alkoxide crosslinking agent for the adhesive agent of this invention, it discovered that the outstanding high temperature performance was acquired more than expected.

Another aspect of the invention provides a process for the preparation of a pressure sensitive adhesive comprising a rubber macromer, preferably an ethylene-butylene macromer and a grafted acrylic polymer that is substantially free of metals or strong acids. The macromers used in the preparation of the adhesives according to the invention preferably have a molecular weight of about 2,000 to about 10,000. The manufacturing method includes reacting an acrylic polymer component with a rubber macromer component, wherein the rubber macromer is substantially free of the catalyst used in the preparation of the rubber macromer component.

One aspect of the invention also provides an adhesive article comprising a pressure sensitive adhesive hybrid polymer, such as industrial tapes, transfer films, and the like. In a particularly preferred embodiment, the hybrid polymer is an ethylene-butylene macromer, 2-ethylhexyl acrylate or a similar acrylic monomer having a low Tg, methyl acrylate or a similar monomer having a high Tg, and preferably hydroxy. Hydroxy group functional monomers such as ethyl acrylate.

As used herein, the term "pressure sensitive adhesive" refers to a viscoelastic material that adheres immediately to most substrates with slight pressure and remains tacky permanently. In addition, as long as the polymer has the properties of a pressure-sensitive adhesive by itself or a function as a pressure-sensitive adhesive by using a mixture with a tackifier, a plasticizer or other additives, the term used herein It is a pressure sensitive adhesive contained in the meaning of.

Adhesive polymers of the present invention include, but are not limited to, rubber-acryl-based polymers comprising grafted acrylic polymer backbones including, but not limited to, ethylene-butylene macromers, ethylene-propylene macromers, and ethylene-butylene-propylene macros It is a hybrid polymer. Typically, the hybrid polymer is prepared by copolymerizing an alkyl acrylate ester monomer in the presence of a macromer comprising a reactive acrylic end group or a methacryl end group. In this way, a comb-type copolymer having an acrylic main chain and a macromer side chain can be obtained.

More specifically, the acrylic polymer backbone used to practice the present invention is formed from acrylate monomers of one or more alkyl acrylates having a low Tg. The monomer with a low glass transition temperature is a monomer having a Tg of less than about 0 ° C. Alkyl acrylates that can be used to practice the present invention preferably have alkyl groups of about 18 or less carbon atoms, preferably about 4 to about 10 carbon atoms. Alkyl acrylates used in the present invention include butyl acrylate, amyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, decyl acrylate, dodecyl acrylate, isomers thereof and combinations thereof This includes. As the alkyl acrylate used in the present invention, 2-ethylhexyl acrylate is preferable.

The monomer system used to prepare the acrylic backbone polymer may be based solely on lower lg alkyl acrylate ester monomers, but preferably contains higher lg monomers and / or functional comonomers, in particular containing carboxyl groups. Preference is given to including a functional monomer and / or more preferably a hydroxyl group-containing functional monomer.

High Tg monomer components, which may be present in the monomer system and preferably present in some embodiments, include methyl acrylate, ethyl acrylate, isobutyl methacrylate and / or vinyl acetate. The monomer having a high Tg is included in an amount of about 50% by weight or less, preferably about 5 to about 50% by weight, more preferably about 10 to 40% by weight, based on the total weight of the hybrid polymer.

In addition, the acrylic backbone polymer may further comprise one or more functional monomers. As said functional monomer, a carboxyl group and / or a hydroxyl group functional monomer is preferable.

The carboxyl group functional monomer may generally be present in the hybrid polymer in an amount of about 7% by weight or less, more generally about 1 to about 5% by weight relative to the total weight of the hybrid polymer. Carboxylic acids useful in the present invention preferably include from about 3 to about 5 carbon atoms, and carboxylic acids useful in the present invention include acrylic acid, methacrylic acid, itaconic acid, and the like. As the carboxylic acid, acrylic acid, methacrylic acid and mixtures thereof are preferable.

In a particularly preferred embodiment, the acrylic backbone comprises a hydroxyl group functional monomer, such as hydroxyalkyl (meth) acrylate ester, and the acrylic polymer used to form the acrylic backbone of the present invention is an acrylic ester / hydride. Preferred are copolymers of oxy (meth) alkyl esters. Examples of the hydroxy group functional monomers include hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate. The hydroxy group functional monomer is usually used in an amount of about 1 to about 10%, preferably about 3 to about 7%.                 

In addition, other comonomers may be used to change the Tg of the acrylic polymer, further improve adhesion to various surfaces, and / or further improve high temperature shear properties. Such comonomers include N-vinyl-pyrrolidone, N-vinyl caprolactam, N-alkyl (meth) acrylamides such as t-octyl acrylamide, cyanoethyl acrylate, diacetone acrylamide, N-vinyl Acetamide, N-vinyl formamide, glycidyl methacrylate and allyl glycidyl ether.

The monomer ratio of the acrylic polymer is adjusted such that the glass transition temperature of the main chain polymer is less than about -10 ° C, preferably in the range of about -20 ° C to about -60 ° C.

The glass transition temperature of the macromers that can be used to prepare the graft copolymers is in the range of about -30 ° C or less, preferably about -50 ° C to about -70 ° C, as measured by differential scanning calorimetry (DSC). Preferably, the macromer is present in an amount of about 5 to about 50 weight percent of the hybrid polymer. Such macromers are commercially available from Kraton Polymers Company. The molecular weight of the macromer may range from about 2,000 to about 30,000, and the molecular weight of the macromer used to practice the present invention is about 2,000 to about 10,000 as measured by gel permeation chromatography (GPC). It may be desirable to range.

Typically, saturated rubber macromers can be prepared using various known methods. As one of these methods, for example, hydroxy from 1,3-butadiene and / or isoprene monomers, as described in US Pat. No. 5,625,005, which is hereby incorporated by reference in its entirety. There is an anionic polymerization method for producing conjugated diene polymers terminated with groups. Further, at least 90%, preferably at least 95, of the unsaturated moieties of low molecular weight monools via catalytic hydrogenation, as described in U.S. Pat. % Can be reduced. Saturated rubber monools suitable for use in the present invention are available from Kraton Polymers Company. Preferred grades for the monools are also Kraton ^(R) L 1203. In the final stage of the macromer preparation reaction, the hydroxy end is reacted to form acrylates or methacrylates according to any of a variety of known methods. Various known methods include strong acid or metal containing catalysts (eg, compounds such as Ti, Sn, etc.), through reaction with acid chlorides or urethane reactions with metal catalysts, as described in US Pat. No. 5,625,005. It includes esterification reaction or transesterification reaction using.

However, it has been found that catalyst residues such as metals or acids present in the macromers used to prepare adhesives based on rubber acrylic hybrid polymers, in particular adhesives containing hydroxy functional group-containing polymers, adversely affect the physical properties of the adhesive. There is a bar. Therefore, while the low level of the said metal or acid can be used for the said use, it is preferable that the said macromer does not contain substantially the catalyst used at the time of the superposition | polymerization. As defined herein, "substantially free" means that even if any catalyst residue is present in the polymerized macromer, it does not cause problems in the preparation of the hybrid polymer. Catalyst residues can be easily removed using methods known in the art.

The hybrid polymer of the present invention can be prepared according to conventional polymerization methods known to those skilled in the art. Examples of such polymerization include, but are not limited to, solution polymerization, suspension polymerization, and bulk polymerization. When the solution polymerization method is used, the graft polymer is synthesized using a solvent mixture according to a conventional free radical technique. The solvent blend, preferably a solvent blend of ethyl acetate, hexane and / or heptane, and toluene imparts the solubility necessary to exhibit good coating behavior at low and high coating weights. In addition, in practicing the present invention, it may be advantageous to reduce the content of residual monomers after polymerization using methods known in the art.

The preferred adhesive composition is preferably crosslinked using a chemical crosslinking agent. In the practice of the present invention, an aluminum crosslinking agent and a titanium crosslinking agent may be used. In order to obtain the high temperature performance of the adhesive according to the present invention, a titanium-containing metal alkoxide crosslinking agent should be used, and the crosslinking agent may be used for hydroxyalkyl (meth) acrylate ester. It has been found that it is a preferred crosslinking agent. The use of titanium crosslinkers can impart a yellowish color to the final product, but this is not a concern for most of the applications. Typically the crosslinking agent is added in an amount of about 0.3% to about 2% by weight relative to the hybrid polymer.                 

It is preferable that the adhesive composition of this invention is provided with adhesiveness. The acrylic polymer component and the rubber component of the hybrid polymer are believed to form a microphase separated structure in the solid phase. This can be supported by the fact that on the viscoelastic temperature spectrum corresponding to each component, two different Tg appear. Tackifier resins useful in the adhesive composition of the present invention are compatible with the rubber macromer phase. Of course, a tackifier compatible with the acrylic polymer phase can be used with any acrylic polymer, and the hybrid polymer of the present invention is no exception. However, such a tackifier is usually derived from natural rosin, and when such a tackifier is used, the aging property of the adhesive becomes poor. The present invention aims to solve this problem. Accordingly, preferred tackifiers for the present invention are synthetic hydrocarbon resins derived from petroleum. Illustrative resins associated with the rubbery phase include resins derived from aliphatic olefins, such as the trade names Wingtack ^(R) available from Goodyear and the trade name Escorez ^(R) 1300 series available from Exxon. A typical C ₅ tackifier resin is a diene-olefin copolymer of piperylene and 2-methyl-2-butene having a softening point of about 95 ° C. As the above-mentioned resins, a product under the trade name Wingtack 95 can be obtained commercially. Generally, the tackifier resin has a ring and ball softening point of about 20 ° C. to about 150 ° C. measured according to the ASTM method. Moreover, Escorez 2000 series (available from Exxon) which is a resin derived from C ₉ aromatic / aliphatic olefins is useful as the tackifying resin useful in the present invention. Hydrogenated hydrocarbon resins are particularly useful as the tackifier resins when the adhesives require long term resistance to oxidation and ultraviolet exposure. Such hydrogenated resins include Escorez 5000 series of hydrogenated alicyclic resins (available from Exxon), resins of Arkon ^(R) P series of hydrogenated C ₉ and / or C ₅ resins (available from Arakawa Chemical), hydrogenated Aromatic hydrocarbon resins Regalrez ^(R) 1018, 1085 and Regalite ^(R) R series resins (available from Hercules Specialty Chemicals). Other useful tackifier resins include Clearon ^(R) P-105, P-115 and P-125 (available from Yasuhara Yushi Kogyo Company of Japan) which are hydrogenated polyterpenes.

Typically, the tackifier resin may be present at a level of 5-50% by weight of the adhesive composition, preferably at a level of about 10-40% by weight of the adhesive composition.

In addition, the formulated adhesive may include, as other ingredients or additives, excipients, diluents, emollients, plasticizers, antioxidants, anti-irritants, opacifiers. ), Fillers such as clay and silica, and mixtures thereof, and preservatives.

The pressure-sensitive adhesive of the present invention may be advantageously used in the manufacture of an adhesive article comprising an industrial tape and a transfer film, but is not limited to the above-mentioned article. Such adhesive articles are useful over a wide temperature range and have improved UV resistance, for example low energy surfaces such as polyolefins such as polyethylene and polypropylene, polyvinyl fluoride, ethylene vinyl acetate, acetal, polystyrene, powder coated paints, and the like. It is attached to a variety of substrates including. Articles of the present invention include supported and unsupported free films and single sided tapes and double sided tapes. In addition, articles of the present invention include, but are not limited to, labels, decals, nameplates, decorative and reflective materials, reclosable fasteners, anti-theft devices, and anti-counterfeiting devices.

Further, in one embodiment of the present invention, the adhesive article comprises an adhesive coated on at least one major surface of a backing comprising a first major surface and a second major surface. Substrates useful in the present invention include, but are not limited to, foams, metals, fabrics, and various polymer films such as polypropylene, polyamides, and polyesters. The adhesive may be present on one or both sides of the substrate. When the adhesive is applied on both sides of the substrate, the adhesives applied to each side may be the same or different from each other.

In the following examples, the adhesive test method described below was used.

Preparation of Coatings

The adhesive solution was cast in a silicone coated release liner, air dried for 15 minutes and then dried for 3 minutes at a temperature of 250 ° F. in a forced air oven. The film was then laminated to a backing film and placed overnight at 22 ° C. and 50% relative humidity. Except as otherwise described, the adhesive film dried as described above has a thickness of 1 mil (25 μm) and the base film is a 2 mil polyester film.

Peel adhesion

According to Test Method No. 1 of PSTC (Pressure Sensitive Tape Council, Northbrook, Illinois) adopted as follows, the peel adhesion at 180 ° of the substrate and the substrate test panel was measured. First, the stainless steel (SS) panel was wetted for 20 minutes or as described separately, and then peel strength was measured. Peel adhesion tests were also performed on high density polyethylene (HDPE) panels. Except as noted, all tests were performed at conditions of 22 ° C. and 50% relative humidity.

shear retention (shear holding power)

Shear holding force was measured according to PSTC test method No. 7 adopted as follows. The test panel was wetted for 15 minutes and then the shear holding force was measured under conditions that impose a 1 kg shear load on the applied 0.5 inch by 1 inch area. The test was also performed on high density polyethylene (HDPE) panels. Except as noted, all tests were performed at conditions of 22 ° C. and 50% relative humidity.

Shear adhesion failure temperature (SAFT)

Specimens bonded at 1 inch by 1 inch size were placed in an oven at 140 ° F. under a 1 kg shear load (wet 15 minutes at room temperature before applying the load to the specimens). The temperature of the oven was then raised every 10 minutes in increments of 10 ° F. and the temperature at which the adhesion failed was recorded.

Example  One

This example relates to the preparation of hybrid polymer solutions using macromers terminated with methacrylate and substantially free of strong acids or metal catalysts. Using GPC, the average molecular weight of the macromers relative to the polystyrene standard was measured, with Mn = 6600 and Mw = 7200 Daltons.

59.73 g 2-ethylhexyl acrylate (2-EHA), 22.72 g ethylene-butylene macromer, 17.05 g methyl acrylate (MA), 5.67 g 2-hydroxyethyl acrylate (2-HEA) To prepare a reaction initiating charge mixture comprising 55.0 g ethyl acetate (EtOAc), 64.19 g hexane (standard mixed isomer grade) and 0.28 g azobis (isobutyronitrile) (AIBN), The filling mixture was charged to a 3-liter four-necked round bottom flask equipped with thermometer, condenser, water bath and slow addition funnel. The starting charge was heated to reflux with stirring. 10 minutes after refluxing the charge, 229.0 g 2-EHA, 128.59 g ethylene-butylene macromer, 65.45 g MA, 21.84 g 2-HEA, 27.5 g hexane, and 236.5 g EtOAc, 55.0 Monomer mixes comprising an initiator mix containing g hexane, 1.38 g AIBN were simultaneously added simultaneously, at 2 and 3 hour intervals, respectively. After the addition of the mix was complete the flask charge was further refluxed for 2 hours. The residual monomer was then collected using an initiator with a short half-life added on a 1 hour cycle, and then the solution was further refluxed for 1 hour. The diluent consisting of 183.3 g of toluene was then slowly added to the contents while cooling the reactor contents to room temperature. There was no tendency to raise the reactor stirring shaft by maintaining the fluid viscosity of the polymer solution throughout the reaction.

The solids content of the polymer solution is 42.7%, and the Brookfield viscosity is 2500 mPa · s. In addition, the average molecular weight of the polymer solution measured using gel permeation chromatography was Mw = 560,000 and Mn = 34,000.

Example  2 and Example  3

Since it was found that adverse effects are obtained when a strong acid catalyst or a metal catalyst is used to prepare the macromers, in each of Examples 2 and 3, the effect of the strong acid catalyst in the macromer polymerization process (Example 2) and the effect of the metal catalyst in the macromer polymerization process (Example 3).

Example  2

A series of polymers were prepared according to the procedure as described in Example 1. The macromer was used to prepare the polymer series comprising p-toluenesulfonic acid (p-TSA) in the corresponding concentration range. Table 1 shows the adverse effects of high levels of p-TSA. Network formation in the polymer led to a sharp increase in solution viscosity during the manufacturing process at high levels of acid. This finally formed a gel to obtain a product that could not be used. This problem can be explained as first showing a tendency for the stirring shaft to rise by the solution. The phenomenon as described above is known as the Weissenberg effect. The Weisenberg effect results in poor mixing, additional power is needed to maintain agitation, and torque is increased. In extreme cases, movement of the shaft bearings and seals of the stirrer may be disturbed. In addition, even when the polymer does not gel, poor flow and leveling may appear during the adhesive coating process.

Table 1

p-TSA (ppm) 75 150 300 500 Observation                                      Fluid viscosity. Shaft rise does not occur. Fluid viscosity. The shaft rises to a minimum Increased viscosity but still fluid. The shaft is slightly raised. High viscosity leads to gel formation.

Example  3

The polymer solution was prepared as in Example 1. Using the macromer, a polymer containing tin in the corresponding concentration range was prepared. Table 2 shows the adverse effects of high levels of tin.

TABLE 2

Sn (ppm) 100 150 300 Observation                                      Fluid viscosity. Shaft lift does not occur, Viscosity increases. Large rise in shaft High viscosity. The shaft rises violently. Gel is formed.

Example  4

A polymer solution was prepared in the same manner as in Example 1 using hydroxypropyl methacrylate at an equimolar concentration instead of the HEA monomer. Using the macromers, polymers containing tin in the concentration ranges as shown in Table 3 were prepared. As a result, no problems appeared during the polymerization process, and it was confirmed that high levels of tin did not affect the monomer.

TABLE 3

Sn (ppm) 120 230 Observation Fluid viscosity. Shaft rise does not occur. The viscosity increased slightly, but the shaft did not rise.

Example  5

This embodiment relates to the production of a polymer when the Tg high acrylic comonomer is used and when the comonomer is not used. Two series of hybrid polymers were prepared according to the procedure in Example 1 except that the diluting solvent was ethyl acetate. In the second series, acrylic acid (AA) was used instead of the HEA. Experiments were designed to determine the use of high Tg monomers, macromer levels, and the effects of hydroxyl groups on carboxyl groups. The results are shown in Table 4.                 

Table 4

Although the viscosity was very high in only one case of polymer solution D, all compositions to be used in the experiments could be prepared according to the procedure described above. For the control of the viscosity, it is preferable to dilute with a hydrocarbon or aromatic hydrocarbon solvent as used in Example 1 instead of ethyl acetate. The molecular weights measured by GPC were all high.

Example  6

This example relates to the adhesion performance test of the polymer prepared in Example 5. The samples prepared in Example 5 were tested according to the procedure described above. The results are shown in Table 5.

Table 5

Through the above results, it can be seen that the shear holding force of the adhesive is very poor in the absence of methyl acrylate, which is a high Tg monomer.

Example  7

This example relates to the effect of adding a titanium crosslinking agent to the polymer solution of Example 5. Sample D and Sample I are not shown in the table because they already show good cohesive strength. A solution consisting of 12.3 g isopropyl alcohol, 15.3 g 2,4-pentanedione and 2.4 g Tyzor ^(R) GBA (available from Du Pont Company, Wilmington) was prepared. Tyzor ^(R) GBA is a 75% solution of bis (2,4-pentanedionate-O, O ') bis (2-propanolato) -titanium in alcohol. The crosslinker solution was stirred into the polymer solution at the concentrations listed in the table (weight to polymer weight) and adhesion performance was measured. The results are shown in Tables 6 and 7.

Table 6

TABLE 7

The results indicate that although the titanium crosslinker is effective in increasing the cohesive strength, a high Tg monomer must be present in the polymer composition in order to obtain high cohesive strength (Sample C and Sample E are sample A and Sample E). B and, and sample H and sample J compared to sample F and sample G). When the crosslinking agent is added, a balance between adhesion and cohesion may be expected, but it can be seen that the polymer F and the polymer G, which are hydroxyl functional polymers, have greatly reduced the peel strength to stainless steel (SS).

Example  8

This example shows the compatibility of the hydrocarbon tackifier resin with the polymer of Example 5. The tackifier resin is dissolved in the polymer solution at a high filling amount (60 parts tackifier to 100 parts of polymer on a dry basis). The solution was cast on a glass plate and then its transparency was visually examined. What was observed to be transparent was evaluated as being compatible. Tackifiers used in this example are Wingtack ^(R) 95 (available from Goodyear Company ⁾ , a resin of C ₅ , and Escorez ^(R) 2596 (available from ExxonMobile), an aromatic / aliphatic resin. As a result of evaluation, the thing which is commercially available is "C" and the one which is not commercially available is shown in Table 8 as "I".

Table 8

Through the above results, it can be seen that the smaller the hydroxyl group functional polymer, the wider the commercial range than the carboxyl group functional material. In addition, unexpectedly, the hydroxy group functional polymer comprising methacrylate, which is a high Tg monomer, i.e., sample H, sample I and sample J are commercially available, but do not include the hydroxy group functional polymer. The polymers, namely Sample F and Sample G, are not commercially available.

Example  9

This example shows the effect on the performance of adhesives formulated using C ₅ aliphatic hydrocarbon tackifier resins. A series of mixtures was prepared while increasing the level of tackifier. On a dry basis, 10 parts, 20 parts and 40 parts tackifier Wingtack 95, 0.8 parts Tyzor GBA and 0.5 parts Irganox ^(R) 1010 (an antioxidant sold by Ciba Specialty Chemicals) were added to 100 parts of polymer J, respectively. Mixed in. The performance of each adhesive was evaluated according to the method in Example 6. In addition, two types of acrylic polymers, DURO-TAK ^(R) 72-8746 (called "A") and DURO-TAK 80-1105 (called "B"), available from National Starch and Chemical Company, were used as controls. Rosin ester tackifiers were formulated using amounts of 15 parts and 40 parts, respectively, for 100 parts of the polymer. The evaluation results are shown in Table 9.

Table 9

As in the above results, since the peel strength to stainless steel, and particularly the peel strength to HDPE, which is a substrate having a low surface energy, was substantially increased, it can be confirmed that the hybrid polymer has excellent reactivity to the tackifier. . The hybrid polymer of the present invention exhibited much higher cohesive strength than the acrylic polymer at a high tackifier loading, and thus had a good balance of physical properties. In the hybrid polymer, heat resistance was much higher than expected as measured by SAFT, and even when the loading amount of the tackifier was very low, the cohesive strength was superior to the acrylic polymer.

Example  10

This example relates to the effect on the performance of adhesives formulated using hydrogenated alicyclic hydrocarbon tackifier resins. A mixture was prepared according to the method described in Example 8 using 40 parts Escorez 5415 and 40 parts Escorez 5600 for 100 parts Polymer J. As the crosslinking agent, Tyzor GBA was used in an amount of 1.2 parts per 100 parts of polymer. Escorez 5415 is a hydrogenated alicyclic resin having a ring and ball softening point of 118 ° C. Escorez 5600 is a hydrogenated aromatic modified alicyclic resin having a ring and ball softening point of 103 ° C. When the two adhesives prepared as described above form a transparent film, it was evaluated as being compatible with the polymer. The thickness of the adhesive coating was 2 mils, and the adhesive performance was evaluated according to the method in Example 6. The results are shown in Table 10. The case evaluated using Wingtack 95 under the same formulation factors and test conditions as described above is shown in the table as a control.

Table 10

Through the above results, the hybrid polymer is compatible with the hydrogenated alicyclic resin, and by using these resins, there was a slight decrease only in the peel strength for the low-energy-based HDPE, and it was confirmed that additional heat resistance was given.

Example  11

This example compares the aluminum crosslinker and the titanium crosslinker. The polymer solution was prepared according to the method in Example 1 and formulated using 40 weight percent Wingtack 95 and 0.8 weight percent Tyzor GBA (75% activity) based on dry polymer weight. A second solution was prepared in the same manner as described above using aluminum tris (acetyl acetonate) in an equivalent concentration (0.7%) instead of Tyzor. The adhesive was then coated and tested according to the procedure described above. The results are shown in Table 11.

Table 11

Through the above results, it can be seen that the aluminum crosslinking agent is less effective in improving the cohesive strength than the titanium crosslinking agent. In order to confirm the superiority of the titanium crosslinker in the present invention, two samples with increased concentrations of aluminum were further prepared and tested. The results are as shown in the table above, and as shown in this table, increasing the level of aluminum showed little positive effect on the shear strength and the peel strength decreased.

Example  12

   This example relates to the effect when the polymer has both a hydroxy functional group and a carboxy functional group. A polymer solution was prepared according to the procedure in Example 1 except that 4% by weight of HEA and 1% by weight of AA were used instead of 5% by weight of HEA, which was the polymer of Example 1. The polymer solution thus produced is referred to as polymer K. A second polymer solution (called Polymer L) was prepared by adding 0.15% by weight of glycidyl methacrylate as an additive component. The adhesive performance of these polymers was tested without further formulation at a dry coating thickness of 2 mils and the results are shown in Table 12.

Table 12

Both Polymer K and Polymer L showed good performance against the unformulated base polymer. In particular, due to the high cohesion and heat resistance, it is possible to accommodate additional tackifiers and / or to extend the formulation limits to reduce the level of crosslinkers. See Table 13 for these results.

Example  13

This example shows whether polymers having hydroxy and carboxy functional groups can be formulated to provide substantially improved heat resistance while maintaining a high level of peel adhesion. In addition, the present Example also shows whether the aluminum crosslinking agent can be used in the above-described case. As shown in Table 13, the polymer solution was formulated using Wingtack 95 tackifier resins and crosslinkers. The weight is expressed based on the weight of the polymer solids. The thickness of the adhesive coating was 2 mils.                 

Table 13

From the above results, it can be confirmed that the heat resistance is substantially increased. In addition, although there is a slight decrease in the heat resistance, it is seen that the physical properties are well harmonized, indicating that the aluminum crosslinking agent can be used together with the polymer L. These results can be compared with the poor result obtained when crosslinking the hydroxy functional polymer of Example 1 using an aluminum crosslinking agent (see Example 11). In addition, when it is important that no color appears, it may be preferable to use an aluminum crosslinking agent.

As will be apparent to those skilled in the art, many modifications and variations of the present invention can be made without departing from the spirit and scope of the invention. The specific embodiments described herein are presented by way of example only, and the invention is to be limited only by the appended claims and all equivalents belonging to the claims.

Claims (43)

A pressure-sensitive adhesive comprising an acrylic polymer copolymerized with a rubber macromer, The acrylic polymer comprises at least one alkyl acrylate monomer comprising an alkyl group having 4 to 18 carbon atoms, and at least one monomer having a glass transition temperature of the homopolymer greater than 0 ° C, The glass transition temperature of the said macromer is -30 degrees C or less, Pressure sensitive adhesive. The method of claim 1, And the macromer comprises poly (ethylene-butylene), poly (ethylene-propylene) or poly (ethylene-butylene-propylene). The method of claim 1, Adhesive of the macromer has a molecular weight of 2,000 to 10,000. The method of claim 1, Adhesives, characterized in that the glass transition temperature of the macromer is -50 ℃ to -70 ℃. The method of claim 1, And the polymer further comprises at least one hydroxyl group functional monomer and / or at least one carboxylic acid functional monomer. The method of claim 5, Adhesive characterized in that the functional monomer is a hydroxyl group functional monomer. The method of claim 5, And the polymer further comprises at least one carboxylic acid functional monomer. The method of claim 5, And the polymer further comprises a glycidyl methacrylate monomer. The method of claim 7, wherein And the polymer is crosslinked using an aluminum crosslinking agent. The method of claim 7, wherein And wherein said polymer further comprises a hydroxyl group functional monomer. The method of claim 9, And wherein said polymer further comprises a hydroxyl group functional monomer. The method of claim 6, And the polymer comprises 2-ethylhexyl acrylate, methyl acrylate and hydroxyethyl acrylate or hydroxypropyl methacrylate. The method of claim 12, Wherein said polymer comprises 2-ethylhexyl acrylate, methyl acrylate and hydroxypropyl methacrylate, further comprising acrylic acid. The method of claim 12, Wherein said polymer comprises 2-ethylhexyl acrylate, methyl acrylate and hydroxyethyl acrylate, further comprising acrylic acid. The method of claim 1, And further comprising a tackifier. The method of claim 15, And said tackifier is a hydrocarbon tackifier. The method of claim 16, And wherein said tackifier is a hydrogenated hydrocarbon tackifier. A pressure-sensitive adhesive comprising an acrylic polymer copolymerized with a rubber macromer, The acrylic polymer includes at least one alkyl acrylate monomer containing an alkyl group having 4 to 18 carbon atoms and is crosslinked using a titanium crosslinking agent. Adhesive, characterized in that. The method of claim 18, And the macromer comprises poly (ethylene-butylene), poly (ethylene-propylene) or poly (ethylene-butylene-propylene). The method of claim 18, Adhesive of the macromer has a molecular weight of 2,000 to 10,000. The method of claim 18, Adhesives, characterized in that the glass transition temperature of the macromer is -50 ℃ to -70 ℃. The method of claim 18, And the polymer further comprises at least one monomer having a glass transition temperature greater than 0 ° C. The method of claim 18, And the polymer further comprises at least one hydroxyl group functional monomer and / or at least one carboxylic acid functional monomer. The method of claim 23, wherein Adhesive characterized in that the functional monomer is a hydroxyl group functional monomer. The method of claim 23, wherein Adhesive characterized in that the functional monomer is a carboxylic acid functional monomer. The method of claim 23, wherein And the polymer further comprises a glycidyl methacrylate monomer. The method of claim 24, And the polymer comprises 2-ethylhexyl acrylate. The method of claim 27, Wherein said polymer further comprises methyl acrylate and hydroxyethyl acrylate or hydroxypropyl methacrylate. The method of claim 28, Wherein said polymer comprises 2-ethylhexyl acrylate, methyl acrylate and hydroxypropyl methacrylate, further comprising acrylic acid. The method of claim 28, Wherein said polymer comprises 2-ethylhexyl acrylate, methyl acrylate and hydroxyethyl acrylate, further comprising acrylic acid. The method of claim 18, Wherein said adhesive further comprises a tackifier. The method of claim 31, wherein And said tackifier is a hydrocarbon tackifier. 33. The method of claim 32, And wherein said tackifier is a hydrogenated hydrocarbon tackifier. A method of making a pressure sensitive adhesive comprising reacting an acrylic polymer component with a rubber macromer component that does not include a catalyst used to make the rubber macromer component, The acrylic polymer comprises at least one alkyl acrylate monomer comprising an alkyl group having 4 to 18 carbon atoms, and at least one monomer having a glass transition temperature of the homopolymer greater than 0 ° C, The glass transition temperature of the macromer is characterized in that -30 ℃ or less, Method for producing pressure sensitive adhesive. The method of claim 34, wherein The macromer comprises poly (ethylene-butylene), poly (ethylene-propylene) or poly (ethylene-butylene-propylene). The method of claim 34, wherein Wherein said macromer does not comprise a metal containing catalyst. The method of claim 34, wherein Wherein said macromer does not comprise a strong acid catalyst. The method of claim 34, wherein The molecular weight of the macromer is characterized in that 2,000 to 10,000. The method of claim 34, wherein The glass transition temperature of the macromer is characterized in that -50 ℃ to -70 ℃. An article of manufacture comprising the adhesive of claim 1. The method of claim 40, And the article is a pressure sensitive adhesive tape. An article of manufacture comprising the adhesive of claim 18. The method of claim 42, wherein And the article is a pressure sensitive adhesive tape.