ES2439890T3 - Hot melt adhesive with low application temperature for cigarette manufacturing - Google Patents

Abstract

Cigarette filter comprising a hot melt adhesive, which can be applied at temperatures between 93 and 149°C (200 and 300°F), whereby the adhesive comprises the following: (i) an ethylene/n-butyl acrylate copolymer comprising a 10 up to 40% by weight of den-butyl acrylate, with a melt index of at least 40 dg/min, or (ii) 20 to 40% by weight of an ethylene/alpha-olefin copolymer, 20 to 40% by weight of plasticizer and 10 to 40% by weight of wax or (iii) 30 to 60% by weight of polyethylene polymer with a melt index of 5000 to 2000 dg/min at 190°C, a density of 0.9 to 0, 93 and a softening point below 110°C.

Description

Hot melt adhesive with low application temperature for cigarette manufacturing

Foundation of the invention

The present invention relates to the use of a hot melt adhesive that is applied at a low temperature to manufacture cigarette filters. In particular, the hot melt adhesives of the present invention are used to attach the seam that surrounds the filter and to anchor the filter element in situ to the rod.

A cigarette with a tip or nozzle based on a standard filter is manufactured following three distinct stages: (1) manufacture of the filter or cap, (2) manufacture of the rod, and (3) placement of the tip.

The cigarette rod consists of a flow or stream of tobacco wrapped by a paper tube, where the paper tube is glued by a line of suitable adhesive. This procedure takes place at speeds ranging from 2000 to 16,000 cigarettes per minute. The weight of the cigarette rod, the diameter and the length are accurately controlled for both price control and tax purposes.

The manufacturing process of the filter is similar in many ways to the manufacture of the rod, but the materials and manufacturing equipment used are different. Tobacco smoking filters are often made from a curled bast of cellulose acetate fibers. The bast is then heated and rolled to make a material about 9 "wide, which contains a homogeneous distribution of fibers. The bast "flowers" in a known manner to separate the fibers, and a high boiling solvent, which is usually known as "plasticizer", namely triacetin, is applied, pulverized or with the help of a wick. The treated bast is given a cylindrical shape and wrapped with paper. Over a period of time, which can be accelerated by heating, the plasticizer initially partially dissolves the surface of the fibers causing them to become sticky and bond with each other at various points of contact. The plasticizer then migrates into the fiber leaving the surface dry, but the fibers are held together.

The treated bast is shaped like a tube and wrapped in a paper to which glue or an adhesive is added along its entire longitudinal axis. Before the paper comes into contact with the material of the bast, adhesive is applied to the center and the edge, thereby forming the anchor and the seam. During this process, heating rods are used to extend the time in which the adhesive joins the tow. The formed filter rod is then passed through cooling plates that fix the adhesive. This procedure must be carried out since the filter is cut immediately into smaller pieces.

In some applications, such as carbon or multi-component filters, a hot melt adhesive is previously applied to the filter paper and then thermally sealed with the filter manufacturing machine.

In conventional manufacture of cigarette filters, a hot melt adhesive applied at 177 ° C (350 ° F) is used for sewing and a second aqueous adhesive is used for anchoring. An aqueous adhesive with triacetin resistance is chosen. Due to the nature of the bast, there is a high degree of radial tension in the glued joint, so that any adhesive used must be able to almost glue the piece almost instantaneously and maintain it during storage and use. This has led to the use of hot melt adhesives, which are characterized by rapid solidification and allow very high speeds.

Hot melt adhesives based on vinyl acetate and ethylene and polyethylene are often used for this filter. They are preferred because they are relatively non-polar and resist the deteriorating effects of triacetin, the most commonly used plasticizer, which sometimes migrates by acting as a solvent for the adhesive and causing the bond or bond to deteriorate.

For example, US Patent 4,326,543 shows filter cigarettes, cigars and other similar products that use non-rolled fibrous filters, which are held by themselves, where the part containing the tobacco is fixed to the fibrous filters by paper. which is specifically coated with a hot melt adhesive. The hot melt adhesives described herein are based on vinyl acetate / ethylene copolymers having a melt index that should not be greater than 20 and preferably is 12 or less than 12.

For example, US Patent 5,947,127 reports on the production of a filtration rod by adding a water soluble polymer in the form of an aqueous solution, a dispersion or in the form of particles to a bast of cellulose ester fiber , so that the amount of water used is controlled by being 25 parts by weight with respect to 100 parts by weight of the bast. Subsequently, the water contained in the rod is removed or the particulate water soluble polymer is melted by heating to bond the fiber and obtain a tobacco filter. Since a copolymer of vinyl alcohol and vinyl ester is used as a water-soluble polymer, they can be mixed with minimal amounts of non-water soluble polymers such as ethylene vinyl acetate, polyolefins, polyesters or polyamides. US Patent 4,221,226 shows hot melt adhesives for bonding filter tows consisting of 25 to 75% by weight of a wax and 75 to 25% by weight of

an adherent hydrocarbon resin. It has been described that optionally ethylene vinyl acetate can be added to the adhesive to increase the fragility of the bond or bond.

The majority of commercially available adhesives used in cigarette manufacturing are either hot melts that require temperatures of 177ºC (350ºF) or aqueous adhesives that provide resistance to triacetin.

However, there are problems associated with the use of conventional hot melt adhesives, which are applied at high temperatures, generally at 177 ° C (350 ° F). These high temperatures increase the risks of the operator or user in terms of burns and inhalation of residual volatile substances. In addition, high temperatures require more energy, which requires more suitable manufacturing facilities. High temperatures can also cause premature wear on application equipment, i.e. nozzles, hoses and storage tanks.

The present invention uses hot melt adhesives with low application temperature, which can be applied at temperatures of the order of 93 ° C to 149 ° C (200 to 300 ° F). The advantages of using such low temperatures include a reduced number of heating elements that are required in the adhesive container, a reduced number of volatile emissions and the reduced risk of injury as well as less wear on the application equipment. The use of low temperature hot melt adhesives can also eliminate the need to use aqueous and hot melt adhesives, since some of the hot melt adhesives of the present invention exhibit excellent resistance to triacetin. In addition, lower temperatures reduce temperatures in the reactivation section of the machinery and eliminate the need for cooling plates. Additionally, the hot melt adhesives of the present invention have a fast fixation rate, a better cutting capacity and are comparable or better in terms of triacetin resistance than hot melt adhesives at 177 ° C (350 ° F).

SUMMARY OF THE INVENTION

It has been found, in accordance with the present invention, that hot melt adhesives based on low temperature application ethylene copolymers provide unexpected advantages or benefits in the manufacture of cigarette filters.

DESCRIPTION OF THE INVENTION

The present invention is directed to the use of hot melt adhesive compositions, which can be applied at temperatures between 93 ° C to 149 ° C (200 to 300 ° F), in the manufacture of cigarette filters. In particular, the present invention is directed to a process for manufacturing cigarette filters, and to cigarette filters, where a hot melt adhesive based on a low temperature ethylene copolymer is applied to at least one longitudinal edge or surface. of porous and / or non-porous wrapping paper. The adhesives of the present invention are also applied to multi-component filters or to other filters that have been prepared by previously applying the melt to the filter paper and then heating the coated paper in the machine that makes the filters. As used herein, low temperatures range from 93 ° C to 149 ° C (200 ° C and 300 ° F), preferably 115 ° C to 135 ° C (240 ° F to 300 ° F).

The present invention is directed to the process and to the filters for cigarettes, which comprise any hot melt adhesive that can be applied at temperatures between 93 ° C and 149 ° C (200 to 300 ° F). Suitable adhesives for use herein include hot melt adhesives prepared from ethylene, n-butyl ethylene acrylate copolymers and ethylene / alpha-olefin copolymers.

I. Hot melt adhesives based on n-butyl acrylate and ethylene

The copolymers of n-butyl and ethylene acrylate (EnBA) used herein are those containing at least 10 to 40% by weight of n-butyl acrylate and having a melt index of at least 40 dg / min, preferably at least 400 dg / min. Preferred copolymers are marketed by Exxon under the trade name XW 23-AH and comprise approximately 33 to 37% by weight of n-butyl acrylate and have a melt index of about 400 dg / min. The amount of copolymer present in the adhesive varies between 5 and 45% by weight, preferably between 10 and 40% by weight.

Mixtures of EnBA copolymers can be used as long as the resulting mixture is within the described ranges of weight percentages of n-butyl acrylate and melt index. Therefore it is possible to mix two copolymers of n-butyl acrylate and ethylene having different melt indexes and different percentages of n-butyl acrylate. In a preferred configuration, the EnBA copolymers described above can be used alone or as a mixture with an EnBA copolymer having a melt index of 40 dg / min.

In addition to the components described above, the adhesive compositions of the present invention may optionally comprise a second EnBA copolymer, in particular one containing 30 to 35, preferably 33% by weight of n-butyl acrylate and having an index of fusion of 6 to 40 dg / min. The

Preferred copolymers are marketed by Elf Autochem under the name of LOTRYL 35BA40 and contain approximately 35% by weight of n-butyl acrylate and have a melt index of about 40 dg / min. The amount of this copolymer present in the adhesive varies between 1 and 25% by weight, preferably between 5 and 20% by weight.

The present invention also contemplates the addition to the adhesive of a polymeric additive chosen from the group consisting of polymers of methyl acrylate and ethylene containing 10 to 28% by weight of methyl acrylate, copolymers of acrylic acid and ethylene having an index of acidity from 25 to 150, copolymers of methyl methacrylate, polyethylene, polypropylene, polymers of poly (butene-1-co-ethylene) and copolymers of low molecular weight and / or of n-butyl acrylate and melt index ethylene low. When said additive is present, it is present in amounts of up to 15% by weight of the composition.

Adhering resins, useful in the EnBA adhesives of the invention include aromatic, aliphatic or aliphatic-aromatic hydrocarbon resins, and hydrogenated derivatives thereof, and terpenes and terpene derivatives having a Ring and Ball softening temperature between 70 ° C and 150 ° C. One skilled in the art would recognize that these tachyifying resins are available with different levels of hydrogenation.

Thermoplastic hydrocarbon resins having a Ring and Ball softening temperature of less than 130 ° C, preferably less than 120 ° C are also included. Representative resins include those derived from styrene, alpha-methylstyrene, and / or vinyl toluene and the polymers, copolymers and terpolymers of styrene, alpha-methyl styrene and / or vinyl toluene. KRYSTALEX® 3085, a low molecular weight thermoplastic hydrocarbon polymer derived largely from alpha-methylstyrenes and having a Ring and Ball softening temperature of 85 ° C and is available from Hercules Inc., is preferred.

The thermoplastic hydrocarbon resins are presented in the adhesive compositions of the present invention in an amount between 10 and 60% by weight of the composition, preferably 20 to 40% by weight.

The thermoplastic hydrocarbon resins are present in the adhesive compositions of the present invention in an amount of 10 to 60% by weight of the composition, preferably 20 to 40% by weight.

The adhesives of the present invention may comprise one or more adhering resins. For example, an adhesive may comprise a-methyl styrene or a-methyl styrene and vinyl toluene.

Other useful adherent resins include those sold under the trade names EASTOAC of Eastman Chemical Company, which are partially hydrogenated cycloaliphatic petroleum hydrocarbon resins, ESCOREZ marketed by Exxon Chemical Company, which is a partially hydrogenated cycloaliphatic petroleum hydrocarbon resin, WINGTACK which is an aromatic, aliphatic petroleum hydrocarbon resin marketed by Hercules, ZONATAC which is a hydrocarbon resin of styrene terpene, manufactured based on d-limonene and marketed by Arizona Chemical.

Waxes can be usefully used in the adhesive compositions of the present invention. Normally waxes are used to modify viscosity and reduce adhesion for concentrations up to 60% by weight, preferably less than 45% by weight. Waxes useful in the adhesives of the present invention include paraffin waxes, microcrystalline waxes, Fischer-Tropsch, polyethylene and polyethylene by-products where the Mw is less than 3000. More preferably, the wax concentration is less than 35% by weight. for high melting waxes.

Paraffin waxes suitable for use in the present invention include those having melting points of the order of 54 ° C to 193 ° C (130 to 200 ° F), such as, for example, PACEMAKER from Citgo, and R-2540 from Moore and Munger; and synthetic low melting microcrystalline waxes or Fischer-Tropsch waxes having a melting point below 180 ° C. The preferred wax is paraffin wax with a melting point of 150 ° C.

The adhesives of the invention preferably contain a stabilizer or antioxidant. Among the applicable stabilizers or antioxidants included here are high molecular weight hindered phenols and multifunctional phenols such as sulfur and phosphorus-containing phenols. The hindered phenols are well known to those skilled in the art and can be characterized as phenolic compounds that also contain sterically bulky radicals in an approximate dose to that of the phenolic hydroxyl group. In particular, tertiary butyl groups are generally substituted on the benzene ring in at least one of the ortho positions with respect to the phenolic hydroxy group. The presence of these sterically bulky substituted radicals near the hydroxyl group serves to retard their stretching frequency and accordingly their reactivity; this impediment therefore influences the stabilizing properties. Representative hindered phenols include 1,3,5-trimethyl2,4,8-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene; pentaerythrityl tetrakis-3 (3,5-di-tert-butyl-4-hydroxyphenyl) propionate; n-octadecyl-3 (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate; 4,4’.methylenebis (2,6-tert-butylphenol); 4,4’-thiobis (6-tert-butyl-ocresol); 2,8-di-tertbutylphenol; 6- (4-hydroxyphenoxy) -2,4-bis (n-octyl-thio) -1,3,5-triazine; di-n-octylthio-ethyl-3,5-di-tert-butyl-4-hydroxy-benzoate; and hexa (3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate) sorbitol.

Commercially available antioxidants include the hindered phenols known as IRGANOX, and available from Ciba-Geigy.

The yield of these antioxidants can be increased using also known synergists, for example thiodipropionate esters and phosphites, in particular distearyl thiodipropionate. When these stabilizers are used, they are generally present in amounts of 0.1 to 1.5% by weight, preferably 0.25% to 1.0%. Depending on the end uses, other additives such as plasticizers, pigments and dyes conventionally added to the hot melt adhesives can be added. In addition, small amounts of additional bonding agents and / or waxes such as paraffin wax can also be incorporated in minimum amounts, ie up to 10% by weight, into the formulas of the present invention.

The adhesive compositions are prepared by mixing the components in the melt at a temperature of about 121 ° C until a homogeneous mixture is obtained, approximately two hours. Various mixing methods are known and any method that results in a homogeneous mixing is satisfactory.

The resulting adhesives are characterized by a viscosity of less than about 4 Pa.s (4000 cps) at 135 ° C. They can be applied at temperatures of 121 ° C to 135 ° C to give rise to superior adhesive bonds even when exposed to a wide variety of environmental conditions. The adhesive has excellent thermal stability that is demonstrated in the thermal stability test at 121 ° C for 260 hours, with no signs of skins, carbonaceous residues or gel formation.

The preferred formula for a hot melt adhesive that is prepared from EnBA copolymers is one that comprises 15 to 40% by weight, preferably 15 to 25% of copolymers of n-butyl and ethylene acrylate having an index of fusion of at least 200 dg / min, preferably at least 300, 25 to 55%, preferably 30 to 40% of adherent resins of alpha-methyl styrene and 15 to 40%, preferably 25 to 35 % of a low melting paraffin wax that can be applied at temperatures of 107 ° C to 135 ° C (225 to 275 ° C). Another preferred formula will comprise 20% of an EnBA copolymer with a melt index of 300 dg / min and 10% of an EnBA copolymer with a melt index of 40 dg / min.

II. Hot melt adhesives based on ethylene and alpha-olefin

Another configuration of the present invention refers to hot melt adhesives prepared from:

a) 20 to 40 parts of ethylene / alpha olefin polymer;

b) 20 to 40 parts of adherent resin; Y

c) 10 to 40 parts of wax.

The ethylene / alpha olefin polymers useful herein are those having a compositional amplitude index of greater than 50% and an Mw / Mn ratio of less than 6. In another configuration the ethylene / alpha olefin polymers will have an index of melting of 40 to 1000 dg / min, a melting point of 71 to 90 ° C, a density of 0.850 to 0.92, an index of amplitude of distribution of the composition greater than 50%, and an Mw / Mn ratio less than 6 Preferably, the ethylene / alpha olefin polymers will have a melt index of 50 to 500 dg / min and a density of 0.885 to 0.90. The ethylene / alpha-olefin polymers can be copolymers of ethylene and any alpha-olefin, for example, butene.

As used herein, the composition distribution index or the short chain branching distribution index refers to the percentage by weight of polymeric molecules having a 50% comonomer content of the median total content in comonomer.

Adherent agents useful in the present invention include aliphatic or cycloaliphatic hydrocarbons, aromatic hydrocarbons, aromatically modified aliphatic or cycloaliphatic hydrocarbons and mixtures thereof. EASTOTAC H100, a hydrogenated cyclopentadiene based bonding agent with a softening temperature of 100 ° C is the most preferred bonding agent.

Other useful bonding agents here include polyterpenes, aromatic modified terpanes and combinations thereof. Hydrogenated derivatives of modified terpene resins are also included here. An example of a commercially available styrene polyterpene is ZONATAC 105L, which has a Ring and Ball softening temperature of about 105 ° C and is marketed by the Arizona Chemical Company.

Preferred bonding agents of the present invention are those having a softening temperature of 90 to 150 ° C. The present invention contemplates that the adhesive composition of the present invention comprises one or more of the adherent resins that promote adhesiveness.

Suitable waxes for use in the present invention include synthetic paraffin waxes of low melting point or polyethylene waxes characterized by a melting point of about 54 ° C to 93 ° C (130 to 200 ° F). The most preferred wax is Citgo PACEMAKER.

The adhesives of the present invention may also contain a stabilizer or antioxidant. Among the applicable stabilizers or antioxidants included here are high molecular weight hindered phenols and multifunctional phenols such as sulfur and phosphorus-containing phenols. The hindered phenols are well known to those skilled in the art and can be characterized as phenolic compounds that also contain sterically bulky radicals in an approximate dose to that of the phenolic hydroxyl group. In particular, tertiary butyl groups are generally substituted on the benzene ring in at least one of the ortho positions with respect to the phenolic hydroxy group. The presence of these sterically bulky substituted radicals near the deprotonated hydroxyl group serves to retard their stretching frequency and accordingly their reactivity; this impediment therefore influences the stabilizing properties. Representative hindered phenols include 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene; pentaerythrityl tetrakis-3 (3,5-di-tert-butyl4-hydroxyphenyl) propionate; n-octadecyl-3 (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate; 4,4’.methylenebis (2,6-tert-butylphenol); 4,4’-thiobis (6-tert-butyl-o-cresol); 2,8-di-tertbutylphenol; 6- (4-hydroxyphenoxy) -2,4-bis (n-octyl-thio) -1,3,5triazine; di-n-octylthio) ethyl-3,5-di-tert-butyl-4-hydroxybenzoate; hexa (3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate) sorbitol and 2,6-ditertbutyl-4-methylphenol ("BHT"). An example of a commercially available antioxidant is IRGANOX 1010, a hindered phenol, marketed by Ciba Geigy.

The yield of these antioxidants can be increased using also known synergists, for example thiodipropionate esters and phosphites, in particular distearyl thiodipropionate. When these stabilizers are used, they are generally present in amounts of 0.1 to 1.5% by weight, preferably 0.25% to 1.0%.

The present invention also contemplates the addition to the adhesive of a polymeric additive selected from the group consisting of polymers of methyl acrylate and ethylene containing 10 to 28% by weight of methyl acrylate, copolymers of acrylic acid and ethylene having a number additional 25 to 150 polymers of polyethylene, polypropylene, poly (butene-1-co-ethylene), copolymers of n-butyl acrylate and ethylene and copolymers of vinyl acetate and ethylene. When said additive is present, it is present in amounts of up to 15% by weight of the composition.

Depending on the contemplated end uses of the adhesives, they may include other additives such as plasticizers, pigments and dyes that will be conveniently added to the hot melt adhesives. In addition, small amounts of additional bonding agents and / or waxes such as microcrystalline waxes, hydrogenated castor oil, amide waxes and synthetic waxes modified with vinyl acetate may also be incorporated, which will be incorporated in small amounts up to 10% by weight , to the formulas of the present invention.

A preferred configuration of the present invention relates to a hot melt adhesive composition comprising:

a) 0.5% IRGANOX 1010;

b) 30% of an ethylene / a-olefin copolymer having an index of amplitude of distribution of the composition

greater than 50%, and an Mw / Mn less than 6;

c) 35% paraffin wax; Y

d) 35% EASTOTAC HA100, partially hydrogenated cyclopentadiene at 100 ° C

III. Polyethylene

The polyethylene polymers useful in this configuration are those that have a melt index of about 5000 to 2000 dg / min at 190 ° C. The polymers will have a Ring and Ball softening temperature of 110 ° C or less and a density of 0.900 to 0.930. A preferred polymer is Eastman Chemical's C10 EPOLENE which has a melt index of 2,250, a Ring and Ball softening temperature of 104 ° C and a density of 0.906. The amount of polymers present in the adhesive varies between 30 and 60% by weight, preferably 50% by weight. In addition, small amounts of additional polymers can be included. The adherent resins useful in these adhesive compositions are aliphatic or aliphatic aromatic resins such as terpenes and styrene terpenes. Exxon ERC 179G having a Ring and Ball softening temperature of 90 ° C is preferred.

Polyethylene adhesives also include a microcrystalline paraffin or wax with a Ring and Ball softening temperature of 130 to 200 ° C, for example, MICROSERE 599 of IGI Bolder having a Ring and Ball softening point of 195 ° F. The wax component is used at levels of 0 to 30% by weight, preferably 10% by weight of adhesive. Other optional waxes may be included in small quantities.

Polyethylene adhesives may also include an antioxidant such as those described above in section II.

The adhesive compositions of the present invention are prepared by mixing the components in the melt at a temperature of about 121 ° C until a homogeneous mixture is obtained which is equivalent to about two hours. Several mixing methods are known to achieve a satisfactory homogeneous mixture.

The resulting adhesives are characterized by a viscosity of less than about 3 Pa s (3000 cps) at 135 ° C. They can be applied at temperatures of 93 ° C to 149 ° C (200 to 300 ° F) to give superior adhesive bonds even when exposed to a wide variety of environmental conditions. The adhesives have excellent thermal stability as characterized by the 260 hour thermal stability test at 121 ° C (250 ° F), which shows no signs of skins, carbonaceous residues or gel formation. In fact, some formulas show thermal stability up to 400 hours at 121 ° C (250 ° F).

IV. Mixes

The present invention also contemplates that the adhesives may be a mixture of some of the polymers or copolymers described above. For example, the base polymer in the adhesive may be a mixture of EnBA and EVA polymers. Other mixtures include polyethylene and EVA mixtures, and poly-a-olefins and EVA mixtures. These and other combinations of polymers could be used as the base adhesive, with the additional ingredients chosen depending on the polymers selected.

The copolymers of vinyl acetate and ethylene (EVA) useful herein are those containing at least 15 to 45% by weight of vinyl acetate and having a melt index of at least about 6 dg / min, preferably at least 400 dg / min The EVA copolymers preferably comprise less than 40% by weight vinyl acetate (VA), more preferably 28% VA. Preferred copolymers are marketed by Exxon under the name of UL 7710 and comprise approximately 28% by weight of vinyl acetate by weight and have a melt index of about 400 dg / min.

Mixtures of copolymers of vinyl acetate and ethylene can be used as long as the resulting mixture is within the described ranges of vinyl acetate by weight and melt index. Therefore it is possible to mix two vinyl and ethylene acetates having different melt indexes and different percentages of vinyl acetate.

In addition to the EVA copolymers described above, the adhesive compositions of the present invention may optionally comprise a second EVA copolymer, specifically one containing approximately 28% by weight of vinyl acetate and having a melt index of 6 to 40 dg / min Preferred copolymers are marketed by Exxon under the name ESCORENE UL 7740 and contain approximately 28% by weight vinyl acetate and have a melt index of about 40 dg / min.

V. Preferred configurations.

The described hot melt adhesives that can be applied at relatively low temperatures below 149 ° C (300 ° F) can be used in the present invention where an adhesive is applied at a low application temperature to at least one longitudinal edge of porous or non-porous wrapping paper. porous. A preferred configuration of an adhesive for the present invention is an adhesive comprising:

a) 50 parts of polyethylene such as EPOLENE C-10 from Eastman Chemicals; b) 40 parts of an adherent resin of aliphatic-aromatic hydrocarbons; c) 10 parts of a microcrystalline wax with a softening point of 195ºF as MICROSERE 5999; d) 0.2 parts of an antioxidant stabilizer such as LOWINOX (BHT) from Great Lakes Chemicals

The resulting adhesive is characterized by a viscosity of less than about 5 Pa s (5000 cps) at 121 ° C, a Ring and Ball softening point of 80 ° C to approximately 115 ° C, bonds that tear the fiber in the wrapping paper between 18 ° C and 51 ° C (0 ° F and 120ºF).

The following examples are merely examples and are not intended to limit the scope of the present invention.

EXAMPLES

In the following examples, which are shown for illustrative purposes only, all proportions are by weight and all temperatures are in degrees Celsius unless otherwise indicated.

In the examples, all adhesive formulas were prepared in a single-blade mixer that was heated to 135 ° C by mixing the components until a homogeneous mixture was obtained.

The adhesives were then subjected to various tests that simulated the properties necessary for a successful commercial application.

The viscosities of the mixture of hot melt adhesives were determined on a Brookfield RVT Thermosel viscometer using a spindle number 27.

The test samples to determine the shear and exfoliation resistances at an elevated temperature were prepared as follows: an adhesive bed was applied at 121 ° C to a strip of Kraft paper of 50 pounds and about 2.54 cm (1 inch) of wide by 7.62 cm (3 inches) long across the entire width of the paper. A second piece of Kraft paper of the same dimensions was placed just above the first piece and a weight of 200 grams was placed on the base of the compound. The width of the compressed adhesive bed was 1/2 inch.

Exfoliation and shearing at elevated temperature were determined by applying a weight of 100 grams in each sample and placing the samples in a mechanical aspiration oven. The temperature was raised in increments of 5.5 ° C (10 ° F) from 38 ° C and the samples were kept at a certain temperature for 15 minutes for conditioning. The heating cycle ended when the final link failed. Exfoliation and shear samples were prepared and analyzed in duplicate. The high exfoliation and shear value shown is equivalent to the average failure temperature of the two links. In some cases, the sample failed as the temperature was adjusted in increments of 10 ° and what happened was recorded.

Adhesion at various temperatures was determined by applying a sphere of 6.35 cm (1/4 inch) of adhesive width to a piece of 5.08 cm (2 inches) by 7.62 cm (3 inches) of wrapping paper not porous and immediately contacting a second piece of paper. The bond hardened at each temperature for 24 hours. The joints were separated manually and the amount of torn fiber (FT) was noted.

Adhesive penetration was measured using a porous wrapping paper. This test is performed to measure the staining of the paper by the adhesive. Six sheets of 5.08 x 2.54 cm (2x1 ”) of wrapping paper were stacked. A 5.35 mm 1/4 "wide bed of adhesive was applied between the two central sheets, and treated at a temperature of 43 ° C (110 ° F) for 24 hours. The penetration of the adhesive into the upper and lower sheet was noted.

Exposure time / fixation time was measured on an automated link meter using a 1 mm (0.04 ”) uncompressed bed applied to 65 lb of corrugated wall. The exposure time measures the amount of time the product can remain in the air, that is, it reaches 100% tear of the fiber, in 10 seconds of compression time. Fixation time is the amount of time required to compress and achieve 100% fiber tear with 1 second of exposure time.

Triacetin resistance was measured after immersing the adhesive bond for 24 hours in triacetin.

EXAMPLE 1

In this example, conventional adhesives were compared with the adhesives corresponding to the present invention with a low application temperature. Comparative Examples A and B are conventional adhesives for gluing the wrapping paper that are applied at 177 ° C (350 ° F). Samples 1-4 correspond to the present invention and are applied at 121 ° C (250 ° F). The formulas of the adhesives studied are shown below:

Sample A: is a commercially available EVA hot melt adhesive, which appears under the designation 34-2760 in the National Starch and Chemical Company

Sample B: it is a hot melt adhesive based on EVA, commercially available, which in the National Starch and

Chemical Company appears under the designation 34-2757.

Sample 1: (not according to the invention)

Amount (% by weight)

 Phenol prevented (antioxidant)

0.5

 150ºF paraffin wax

31

ESCORENE UL 7710 (EVA, MI 400 dg / min, 28% VA) 21 ESCORENE UL 7740 (EVA, MI 40 dg / min, 28% VA) 11 KRISTALEX 3085 (a-methylstyrene, 85ºC) 37

Sample 2: BHT (antioxidant) 0.5 EPOLENE C10, 104 ° C (polyethylene polymer) 50 ECR 179G (hydrocarbon resin) 40 Microcrystalline wax 195ºF 10

Sample 3: Disabled phenol (antioxidant) 0.5 Paraffin wax 150ºF 31 EXXON XW 23-AH (EnBA, 33% BA, MI 300 dg / min) 21

ELF AUTOCHEM 35BA40 (EnBA, 33% BA, MI 40 dg / min) KRISTALEX 3085 (a-methylstyrene, 85ºC)

11 37

5

Sample 4: Impaired phenol (antioxidant) Paraffin wax, 150ºC EASTOTAC H100-R Poly-alpha-olefin, 100ºC  0.5 35 30 35

10

The results are shown below in table 1:

TABLE 1

Sample A *

Sample B * Sample 1* Sample 2 Sample 3 Sample 4

Viscosity @ Application temperature

-4400 cps -2735 cps -2390 cps -3600 cps -3025 cps -2820 cps

Adhesion @ application temperature

Temp. ambient.

100.50% 100.50% 100% 100% 100% 100%

40th

100% 100% 100% 100% 100% 100%

100º

100% 75.50% 100% 100% 100% 100%

Penetration @ 110ºF

Light Light Very light Very light Light Light

Triacetin resistance 24 hours

0% fiber tear 25% fiber tear 0% fiber tear 80% fiber tear 0% fever tear 0% fiber tear

Exfoliation / Shearing

Adj 130º / Adj 180ºF Adj 130º / Adj 180ºF 110º / 150ºF 110º / Adj 190ºF 100º / Adj 150ºF 100º / Adj 150ºF

Stability 260 hours

@ 350ºF @ 350ºF @ 250ºF @ 250ºF @ 250ºF @ 250ºF

Carbonaceous residue

Very light Any Any Any Any Any

ER

Any Any Any Any Any Any

Others

Any YES. Misty -24.0% Any Any YES. Separation Any

Delta visc.

-51.0% 1.4% 13.3% -0.9% 2.1%

4 ”wide bed @ Application temperature Exposure time with 10 second compression

1.7 sec 1.0 sec 2.0 sec 4.0 sec 1.5 sec 2.0 sec

Fixing time with exposure time of 1 second

Partial FT = 1.3 secs Full FT = 3.3 secs Partial FT = 4.0 secs Full FT = NA Partial FT = 0.7sec Full FT = 2.0sec Partial FT = 0.7 sec FT full = 1.1 sec Partial FT = 1.5secs Full FT = 6.0 secs Partial FT = 20secs Full FT = 4.3 secs

* reference samples

15 The results in Table 1 above indicate that the adhesives that are applied at low temperature, samples 1,2,3, and 4, have a good adhesion comparable to conventional adhesives. Samples 1 and 2 have a higher degree of penetration and have good thermal stability. The large change in viscosity observed with samples A and B at 260 hours indicates that these adhesives are not stable; EVA is degrading. Sample 2 exhibits excellent fiber tearing even after 24 hours of exposure to triacetin.

A significant difference between the adhesives of the present invention and conventional adhesives is that the adhesives of the present invention have a long exposure time and a fast fixing time that allows for quick drying and fixing before the cut occurs. of the cigarette

Claims (18)

1. Cigarette filter comprising a hot melt adhesive, which can be applied at temperatures between 93 and 149 ° C (200 and 300 ° F), so that the adhesive comprises the following:

(i)

 an ethylene / n-butyl acrylate copolymer comprising 10 to 40% by weight of n-butyl acrylate, with a melt index of at least 40 dg / min, or

(ii)

 20 to 40% by weight of an ethylene / alpha-olefin copolymer, 20 to 40% by weight of plasticizer and 10 to 40% by weight of wax or

(iii) 30 to 60% by weight of polyethylene polymer with a melt index of 5000 to 2000 dg / min at 190 ° C, a density of 0.9 to 0.93 and a softening point of less than 110 ° C.

2.

Cigarette filter according to claim 1, alternative (i) further comprising a second copolymer of vinyl acetate and ethylene, wherein the second copolymer of vinyl acetate and ethylene consists of 25 to 35% by weight of acrylate of n-butyl

3.

Cigarette filter according to claim 2, wherein the second copolymer of ethylene and n-butyl acrylate has a melt index of 40 dg / min and comprises 35% of ethylene and n-butyl acrylate

Four.

Cigarette filter according to claim 1, alternative (i) so that the adhesive consists of:

(to)

up to 40% by weight of ethylene / n-butyl acrylate, comprising 10 to 40% by weight of n-butyl acriclate, with a melt index of at least 400 dg / min;

(b)

10 to 60% by weight adherent agent;

(C)

0 to 35% by weight wax; Y

(d)

Optionally, 1 to 25% by weight of a second ethylene / n-butyl acrylate, with a melt index of 40 dg / min.

5.

Cigarette filter according to claim 1, alternative (i) wherein the hot melt adhesive consists of:

a) 15 to 40% of n-butyl / ethylene acrylate copolymers having a melt index of at least 200 dg / min; b) 25 to 55% a-methylstyrene adherent resins and c) 15 to 40% of a low melting paraffin wax

6.

Cigarette filter according to claim 4, further comprising a polymeric additive selected from the group consisting of polymers of methyl acrylate and ethylene, containing 10 to 28% by weight of methyl acrylate, copolymers of acrylic acid and ethylene which they have an acid number of 25 to 150, copolymers of methyl (meth) acrylate, polyethylene, polypropylene and poly (butane-1-co-ethylene) polymers and ethylene / n-butyl acrylate copolymers with low molecular weight and / or low melt index and combinations thereof.

7.

Cigarette filter according to claim 1, alternative (ii) wherein the ethylene / alpha-olefin copolymer has a composition amplitude index greater than 50% and an Mw / Mn less than 6.

8.

Cigarette filter according to claim 1, alternative (ii) wherein the ethylene / alpha-olefin copolymer has a melt index of 40 to 1000 dg / min, a melting point of 71 to 90 ° C, a density of 0.850 to 0 , 92, a CDBI value greater than 50% and a value of Mw / Mn less than 6

9.

Cigarette filter according to claim 1, alternative (ii) further comprising a polymeric additive selected from the group consisting of polymers of methyl acrylate and ethylene, containing 10 to 28% by weight of methyl acrylate, acid copolymers acrylic and ethylene having an acid number of 25 to 150, polyethylene, polypropylene, poly (butane-1-co-ethylene) polymers, ethylene / n-butyl acrylate (EnBA) copolymers and ethylene acetate acetate copolymers EVA vinyl) and combinations thereof.

10.

Cigarette filter according to claim 1, alternative (i) wherein the adhesive comprises EVA blends of EnBA and EVA polymers.

eleven.

Cigarette filter according to claim 1, alternative (iii) wherein the hot melt adhesive comprises:

a) 50 parts of polyethylene; b) 40 parts of an adherent resin based on aliphatic-aromatic hydrocarbons c) 10 parts of a microcrystalline wax with a softening point of 90.6ºC (195ºF) and d) 0.2 parts of an antioxidant stabilizer 12. Procedure for the manufacture of a cigarette filter, which consists of applying a hot melt adhesive at a temperature between 93 and 149 ° C (200 and 300 ° F) to paper for wrapping porous and / or non-porous filters, where the adhesive comprises the following: (i) Ethylene / n-butyl acrylate copolymer comprising 10 to 40% by weight of butyl acrylate, with a melt index of at least 40 dg / min and optionally a second n-butyl acrylate copolymer wherein the second copolymer of ethylene and n-butyl acrylate comprises 25 to 35% by weight of n-butyl acrylate; or (ii) 20 to 40% by weight of an ethylene / alpha-olefin copolymer, 20 to 40% by weight of plasticizer and 10 to 40% by weight of wax or (iii) 30 to 60% by weight of polyethylene polymer with a melt index of 5000 to 2000 dg / min at 190 ° C, a density of 0.9 to 0.93 and a softening point of less than 110 ° C.

13.

Method according to claim 12, alternative (i), wherein the adhesive comprises the following:

a) 10 to 40% by weight of ethylene / n-butyl acrylate, comprising 10 to 40% by weight of n-butyl acrylate, with a melt index of at least 400 dg / min; b) 10 to 60% by weight of adherent agent; c) 0 to 35% by weight of wax; and d) optionally, 1 to 25% by weight of a second ethylene / n-butyl acrylate, so that the second ethylene / n-butyl acrylate consists of 33 to 35% by weight of n-butyl acrylate, with a melt index of 40 dg / min

14.

Method according to claim 12, alternative (i), wherein the adhesive comprises the following:

a) 15 to 40% by weight of ethylene / n-butyl acrylate copolymer with a melt index of at minus 200 dg / min; b) 25 to 55% by weight of alpha-methylstyrene adherent resin and c) 15 to 40% of a paraffin wax with low melting point.

fifteen.

Process according to claim 12, alternative (i), wherein the ethylene / alpha-olefin copolymer has a CDBI value greater than 50% and an Mw / Mn value less than 6.

16.

Process according to claim 12, alternative (ii), wherein the ethylene / alpha-olefin copolymer has a melting point of 40 to 1000 dg / min, a melting point of 71 to 90 ° C, a density of 0.850 to 0, 92, a CDBI value greater than 50% and an Mw / Mn value less than 6.

17.

Process according to claim 12, alternative (i), wherein the adhesive comprises mixtures of EnBA and EVA polymers.

18.

Method according to claim 12, alternative (iii), wherein the adhesive comprises:

a) 50 parts of polyethylene; b) 0 parts of an adherent resin of aliphatic-aromatic hydrocarbons; c) 10 parts of a microcrystalline wax with a softening point of 90.6ºC (195ºF) and d) 0.2 parts of an antioxidant stabilizer.