Hot melt adhesive composition for safe paper packaging

Abstract

The present invention relates to a hot melt adhesive composition for safe paper packaging comprising a plasticizer blend, the use of the hot melt adhesive composition in safe paper packaging and articles produced with the hot melt adhesive composition of the invention.

Description

Technical Field

[0001] The present invention relates to a hot melt adhesive composition for secured paper packaging comprising a plasticizer blend, the use of the hot melt adhesive composition in secured paper packaging and articles produced with the hot melt adhesive composition of the invention. Background Art

[0002] Packaging waste accounts for a major portion of the total global waste volume. Therefore, developing and promoting sustainable alternatives to reduce the amount of packaging waste is one of the challenges facing industry today, especially in light of the growth of e-commerce. Paper has emerged as an environmentally friendly and sustainable alternative to plastic. Therefore, there is a high demand for paper packaging and corresponding materials to help produce suitable packaging products.

[0003] Hot melt adhesives are found to be suitable adhesives in paper packaging production due to their solvent-free nature, fast forming bonding, and cost effectiveness.

[0004] US 5747573 discloses a high heat resistant hot melt adhesive composition comprising: a) about 20 to 80 parts by weight of an amorphous poly-alpha-olefin butene-propylene-ethylene-terpolymer, b) about 5 to 40 parts by weight of a solid benzoate plasticizer, and c) about 10 to 70 parts by weight of a tackifier, wherein the adhesive composition has an elevated peel value greater than 70°C (160°F).

[0005] US 5627229 relates to a hot melt adhesive composition comprising: 5 to 40% by weight of a cyclohexanedimethanol dibenzoate plasticizer; 20 to 80% by weight of a tackifier selected from aromatic tackifying resins, aromatic-aliphatic tackifying resins, aliphatic tackifying resins, rosin-derived tackifying resins, and mixtures thereof; and 5 to 35% by weight of a thermoplastic polymer, wherein the composition is cold-flowed at ambient temperature for a controlled period of time after application before subsequent modulus increase. The hot melt adhesive composition can be used, for example, to secure cigarette cartons, carton assemblies, or in the production of disposable articles.

[0006] US 5853864 describes an article resistant to moisture-induced debonding comprising a substrate joined to a second layer by a spray-applied adhesive, the adhesive comprising: a) 10 to 40 parts by weight of a thermoplastic block copolymer selected from ABA block copolymers, A-(BA)nBA block copolymers (where n is an integer of 1 or greater), and radial block copolymers (where each A comprises a polystyrene block and each B comprises a rubbery block); b) 30 to 75 parts by weight of a tackifying resin selected from rosin-derived tackifying resins, aliphatic tackifying resins, mixed aromatic-aliphatic tackifying resins, and mixtures thereof; c) 5 to 40 parts by weight of a cyclohexanedimethanol dibenzoate plasticizer, wherein after the adhesive is sprayed and cooled to ambient temperature, the adhesive retains sufficient fluidity for a sufficient time to wet or penetrate the substrate or second layer to form a moisture resistant bond. The specific examples in US 5853864 use a large amount of cyclohexanedimethanol dibenzoate plasticizer, which results in a very short open time and does not produce good adhesion to paper. This therefore makes the composition disclosed therein unsuitable for the use disclosed in the context of the present invention, i.e., for use in secure paper packaging. It is clear from US 5853864 that completely different uses of the adhesive composition disclosed therein are envisaged.

[0007] US 6034159 discloses a hot melt adhesive for multi-purpose bookbinding comprising: a) about 25% to about 40% by weight of a styrene-isoprene-styrene block copolymer having a styrene content of about 15% to about 35% by weight; b) about 25% to about 50% by weight of at least one compatible tackifying resin selected from the group consisting of rosin and rosin esters; terpenes and modified terpenes; aliphatic, alicyclic and aromatic hydrocarbons; hydrogenated derivatives and mixtures thereof; c) about 10% to about 30% by weight of a synthetic high melting point wax having a melting point above about 90°C; d) about 5% to about 30% by weight of a solid benzoate plasticizer; e) not more than about 25% of a compatible wax selected from the group consisting of paraffin wax, microcrystalline wax and mixtures thereof; and f) not more than about 15% of a compatible polymer selected from the group consisting of homopolymers, copolymers and terpolymers of ethylene; homopolymers, copolymers and terpolymers of propylene; rubbery block copolymers and mixtures thereof.

[0008] US 5026756 discloses a solid non-aqueous hot melt adhesive composition comprising a polymer, a tackifier, and 1,4-cyclohexanedimethanol dibenzoate in a plasticizing amount ranging from about 5 to 40 weight percent.

[0009] US5624986 relates to a hot melt adhesive composition comprising: (a) about 5 to 50 weight percent of a plasticizer comprising an alicyclic or aromatic ester of phthalic acid or an alicyclic polyester of an aromatic carboxylic acid, which is solid at room temperature; (b) about 20 to 80 weight percent of a tackifier selected from aromatic tackifying resins, aromatic-aliphatic tackifying resins, aliphatic tackifying resins and rosin-derived tackifying resins and mixtures thereof; and (c) about 0 to 55 weight percent of a thermoplastic polymer; wherein the composition, after application and cooling, cold flows at ambient temperature for a controlled period of time before subsequent increase in modulus (G').

[0010] However, it has been found that currently available hot melt technologies and products cannot meet the needs of recently developed e-commerce paper packaging applications, either due to poor adhesion to dense paper or due to lack of heat resistance and bonding security within the typical use window of -20 to 50°C. Although high-performance hot melt adhesives show good bonding properties to paper, the bonding action cannot be guaranteed. Rather, the paper packaging can be opened and resealed, which is undesirable in a secure paper packaging.

[0011] Therefore, there is still a need for adhesive compositions which are able to produce safe paper packaging and which can preferably be used in fast automated packaging lines. Summary of the invention

[0012] It has surprisingly been found that this need can be addressed by a hot melt adhesive composition comprising a plasticizer blend.

[0013] A hot melt adhesive composition is provided, wherein based on the total weight of the composition, the composition comprises:

[0014] a) 10 to 60% by weight of a thermoplastic block copolymer,

[0015] b) 30 to 70 wt % of a tackifier; and

[0016] c) 2 to 40% by weight of a plasticizer blend,

[0017] Characterized in that the plasticizer blend comprises: a solid plasticizer P1 in an amount not more than 20 wt % based on the total weight of the composition, and a liquid plasticizer P2. It was found that the preferred range of solid plasticizer P1 is 5 wt % to 16 wt % based on the total weight of the composition. Therefore, taking into account the presence of liquid plasticizer P1, the lower limit of the plasticizer range is preferably at least 5 wt %.

[0018] The hot melt adhesive composition of the present invention surprisingly shows the desired combination of long open time and safe bonding. After bonding, the adhesive composition of the present invention is observed to harden and rigid to produce excellent cohesion and heat resistance, resulting in destructive paper tearing when the package is opened. It is found that this combination of properties makes the hot melt adhesive of the present invention suitable for use in automated packaging lines while meeting the requirements of safe paper packaging. DETAILED DESCRIPTION

[0019] The solid plasticizer in the present invention refers to a plasticizer that is solid at room temperature, preferably with a melting point greater than 25°C. The liquid plasticizer in the present invention refers to a plasticizer that is liquid at room temperature. The melting point can be determined by DSC (differential scanning calorimetry). The room temperature in the present invention refers to a temperature range of 20°C to 23°C. Therefore, it will be understood by those skilled in the art that the solid and liquid plasticizers used in the present invention are different from each other.

[0020] Within the scope of the present invention, hot-melt adhesive composition, adhesive composition, composition according to the invention and composition are used synonymously, if not stated otherwise.

[0021] The hot melt composition of the present invention comprises a thermoplastic copolymer, a tackifier and a plasticizer blend. Each component will be described in more detail below:

[0022] a) Thermoplastic block copolymers

[0023] Based on the gross weight of the hot melt adhesive composition, the hot melt adhesive of the present invention comprises 10 to 60 wt %, preferably 20 to 40 wt % of thermoplastic copolymer.Thermoplastic block copolymer is preferably selected from ABA block copolymer, (AB) n or A-(BA) nBA block copolymer, wherein n is 1 or a larger integer, each A comprises polystyrene block and each B comprises rubbery block.A block is preferably a homopolymerized polystyrene.However, other vinyl aromatic monomers can be used to prepare homopolymerized or copolymerized plastics or glassy ends or in A blocks.B block generally comprises a rubbery polymer derived from a diene monomer including isoprene and butadiene.The midblock can be post-processed by hydrogenation or other treatments to improve its thermal stability, i.e., SEPS from hydrogenated SIS or SEBS from hydrogenated SBS.In a preferred embodiment, the thermoplastic copolymer is a blend of styrene-isoprene-styrene copolymer (SIS) or SIS and styrene-butadiene-styrene block copolymer (SBS). In a preferred embodiment, the SIS and / or SBS block copolymers may also be hydrogenated.

[0024] In a preferred embodiment, the block copolymer is provided as a blend of polymers, which blend preferably also comprises one or more polymers selected from the group consisting of styrene-ethylene-butylene-styrene copolymers (SEBS), styrene-ethylene-propylene-styrene copolymers (SEPS), ethylene-vinyl acetate copolymers (EVA) or copolymers and polymers derived from olefins.

[0025] In a preferred embodiment, the block copolymer is a styrene-isoprene-styrene copolymer (SIS), or a blend of SIS and a styrene-butadiene-styrene block copolymer (SBS), or a blend of SIS and a styrene-butadiene-styrene block copolymer (SBS) with SEBS or / and SEPS, EVA or a polyolefin polymer.

[0026] In a preferred embodiment, the block copolymer is a linear SIS block copolymer, which optionally contains SBS blocks and has a styrene content of 12% to 50%, preferably 15% to 45%. The block copolymer can also be a blend of two or more, preferably two or three, linear SIS block copolymers, which optionally contain SBS blocks and have a styrene content of 12% to 50%, preferably 15% to 45%.

[0027] The styrene content in the adhesive composition of the present invention is preferably 15 to 45 wt % based on the total weight of the composition. In a preferred embodiment, the styrene content in the composition is achieved by using a mixture of a high styrene content SIS block copolymer and a low styrene SIS block copolymer.

[0028] b) Tackifier

[0029] The hot melt adhesive composition of the present invention comprises 30 to 70% by weight, preferably 40 to 65% by weight, of a tackifier, based on the total weight of the composition.

[0030] In a preferred embodiment, the tackifier is selected from the group consisting of aliphatic, cycloaliphatic and aromatic hydrocarbon resins and their hydrogenated derivatives, rosin and rosin derivatives, terpenes and modified terpenes and mixtures thereof.

[0031] Tackifiers useful in the adhesives of the present invention include: rosin derivatives, including wood rosin; tall oil, tall oil derivatives, rosin ester resins, natural and synthetic terpenes and aliphatic or mixed aromatic-aliphatic tackifying resins.

[0032] Aromatic monomers that can be used to form the aliphatic-aromatic adhesive composition of the present invention can be prepared from any monomer having a large amount of aromatic quality and containing polymerizable unsaturated groups. Typical examples of such aromatic monomers include: styrene monomers styrene, α-methylstyrene, vinyltoluene, methoxystyrene, tert-butylstyrene, chlorostyrene, etc.; indene monomers, including indene, methylindene, etc. Aliphatic monomers are usually natural and synthetic terpenes, which contain C5 and C6 cyclohexyl or cyclopentyl saturated groups, which may also contain a variety of essentially aliphatic ring substituents. Aliphatic tackifying resins can be prepared by polymerizing a feed stream containing enough aliphatic monomers so that the resulting resin exhibits aliphatic characteristics. Such feed streams may contain other aliphatic unsaturated monomers, such as 1,3-butadiene, cis-1,3-pentadiene, trans-1,3-pentadiene, 2-methyl-1,3-butadiene, 2-methyl-2-butene, cyclopentadiene, dicyclopentadiene, terpene monomers, etc. Mixed aliphatic-aromatic resins contain sufficient aromatic monomer and sufficient aliphatic monomer and optionally other C3-C8 unsaturated monomers to produce a resin having both aliphatic and aromatic character.

[0033] Adhesive composition of the present invention can contain rosin and rosin derivatives as tackifier.Rosin is a solid material naturally present in pine oleoresin, which is typically derived from the oil-based (oleo resinous) extrudates of living trees, from aging stumps and from tall oil as a by-product of kraft paper manufacturing.After obtaining rosin, it can be processed by hydrogenation, dehydrogenation, polymerization, esterification, etc.Rosin is typically divided into gum rosin, wood rosin and tall oil rosin.This material can be used unmodified, and can be used in the form of esters of polyols in addition, and can be polymerized by the inherent unsaturation of molecules.These materials are commercially available and can be blended into the adhesive composition by using standard blending techniques.

[0034] Representative examples of such rosin-derived tackifying resins include pentaerythritol esters of tall oil, gum rosin, wood rosin, or mixtures thereof.

[0035] Representative examples of such aliphatic resins include hydrogenated synthetic C9 resins, synthetic branched and unbranched C5 resins, and mixtures thereof.

[0036] Representative examples of such aromatic aliphatic tackifying resins include styrenated terpene resins, styrenated C5 resins, or mixtures thereof.

[0037] The tackifier resin may be selected from fully hydrogenated hydrocarbon resins, partially hydrogenated hydrocarbon resins, or blends thereof; blends are preferred.

[0038] In particularly preferred embodiments, the tackifier resin is selected from one or more of the following categories:

[0039] i) hydrocarbon resins having C5 units; DCPD (dicyclopentadiene) hydrogenated resins; C9-modified DCPD hydrogenated resins; C9-modified hydrocarbon resins having C5 units; hydrogenated resins having C5 units;

[0040] ii) terpene resins;

[0041] iii) Partially hydrogenated C9 type aromatic resins.

[0042] c) Plasticizer

[0043] The hot melt adhesive composition according to the present invention is characterized in particular by its plasticizer blend, wherein based on the total weight of the composition, the plasticizer blend is included in the composition in an amount of greater than 5 to 40 wt %, typically greater than 5 to 35 wt %, preferably 5.5 to 35 wt %, more preferably 7 to 30 wt %, most preferably 7 to 26 wt %. The plasticizer blend comprises a first plasticizer P1 that is solid at room temperature and a second plasticizer P2 that is liquid at room temperature. Without being bound by theory, it is believed that the plasticizer blend used in the hot melt adhesive of the present invention leads to the advantageous combination of the observed long open time and high bond strength associated with the hot melt adhesive composition of the present invention.

[0044] In a preferred embodiment, the melting point of the first plasticizer P1 compound is at least 60° C., preferably at least 80° C. In a further preferred embodiment, the plasticizer P1 is a benzoate plasticizer comprising a cycloaliphatic or aromatic ester of phthalic acid, or a cycloaliphatic polyester of an aromatic carboxylic acid, which is solid at room temperature. In a particularly preferred embodiment, the plasticizer P1 is 1,4-cyclohexanedimethanol benzoate.

[0045] Based on the gross weight of the adhesive composition, the amount of the first plasticizer P1 in the adhesive composition is advantageously no more than 16 wt %. Surprisingly, limiting the amount of the first plasticizer P1 within the claimed scope further improves the performance of the adhesive composition. Preferably, based on the gross weight of the adhesive composition, the first plasticizer P1 is present in the adhesive composition in an amount of no more than 15 wt %. Suitably, based on the gross weight of the adhesive composition, the first plasticizer P1 is present in the adhesive composition in an amount of 5 wt % to 15 wt %.

[0046] The plasticizer blend further comprises a second plasticizer P2 which is liquid at room temperature. In a preferred embodiment, the plasticizer P2 is contained in the adhesive composition in an amount of not more than 10 wt.-%, preferably 0.5 to 10 wt.-%, based on the total weight of the adhesive composition.

[0047] It will be appreciated by those skilled in the art that the change in the amount of P1 and P2 (and any other plasticizer present in the plasticizer blend) will affect the total amount of the plasticizer blend. For example, the amount of the plasticizer blend in the preferred composition according to the present invention can be, based on the gross weight of the composition, 7 wt % or 8 wt % or 9 wt % or 10 wt % or 11 wt % or 12 wt % or 13 wt % or 14 wt % or 15 wt % or 16 wt % or 17 wt % or 18 wt % or 19 wt % or 20 wt % or 21 wt % or 22 wt % or 23 wt % or 24 wt % or 25 wt % or 26 wt %. When P1 and P2 are the only plasticizers present in the composition according to the present invention, the total amount of the plasticizer blend will be equal to the amount of P1 and P2.

[0048] The liquid plasticizer P2 is preferably selected from naphthenic and / or paraffinic mineral oils.

[0049] The hot melt adhesive composition of the present invention may include additional components, such as stabilizers and antioxidants. In a preferred embodiment, the amount of additional components in the composition (i.e., in addition to one or more thermoplastic block copolymers, one or more tackifiers, solid plasticizer P1 and liquid plasticizer P2) does not exceed 0.3 to 1% by weight based on the total weight of the composition.

[0050] Suitable antioxidants are, for example, hindered phenols, sulfur-based antioxidants and phosphorus-based antioxidants.

[0051] Hot melt adhesive compositions have many advantageous properties, such as long open time and strong adhesion. In a preferred embodiment, the composition of the present invention is characterized by at least one of the following properties:

[0052] i) an open time of 30 to 240 seconds, preferably 90 to 210 seconds;

[0053] ii) Temperature resistance range is -20 to 50°C;

[0054] iii) fiber tearing at high and slow peeling speeds;

[0055] The adhesive composition according to the invention exhibits surprisingly long open times, a wider working window and strong adhesion to dense paper, making it particularly suitable for paper packaging. In addition, the composition according to the invention exhibits excellent adhesive properties within a wide temperature window (e.g., -30°C to 50°C), as well as excellent cohesive strength, even at elevated temperatures (e.g., not higher than 50°C). Therefore, another subject of the present invention is the use of the hot-melt adhesive composition according to the invention in paper packaging, preferably in an automated paper packaging production line.

[0056] Due to the increased adhesion, paper packages sealed with the hot-melt adhesive composition according to the invention cannot be resealed, which is particularly useful in safety paper packages. Therefore, the hot-melt adhesive composition according to the invention is preferably used in the production of safety paper packages.

[0057] Another subject of the present invention is an article comprising at least two layers bonded to each other with a hot melt adhesive composition according to the invention. Preferably, at least one of these layers comprises cellulose fibers. In a particularly preferred embodiment, the article is selected from: sealable paper bags, especially those that can accommodate up to 2 kg weight; and secure paper packaging.

[0058] It will be clear from the foregoing that the present invention may be defined in accordance with one or more of the following statements:

[0059] 1. A hot melt adhesive composition, wherein based on the total weight of the composition, the composition comprises:

[0060] a) 10 to 60% by weight of a thermoplastic block copolymer,

[0061] b) 30 to 70 wt % of a tackifier; and

[0062] c) greater than 5 to 40% by weight of a plasticizer blend,

[0063] Characterized in that the plasticizer blend comprises: a solid plasticizer P1 in an amount of 5 to 16 wt % based on the total weight of the composition, and a liquid plasticizer P2.

[0064] 2. A hot melt adhesive composition according to statement 1, characterized in that the thermoplastic block copolymer is selected from ABA block copolymers, (AB)n or A-(BA)nBA block copolymers, wherein n is an integer of 1 or greater, each A comprises a polystyrene block and each B comprises a rubbery block.

[0065] 3. The hot melt adhesive composition according to statement 1 or 2, characterized in that the thermoplastic copolymer is a styrene-isoprene-styrene copolymer (SIS).

[0066] 4. The hot melt adhesive composition according to statement 1 or 2, characterized in that the thermoplastic copolymer is a blend of SIS and styrene-butadiene-styrene block copolymer (SBS).

[0067] 5. A hot melt adhesive composition according to statement 1 or 2, characterized in that the thermoplastic copolymer is a blend of SIS and styrene-butadiene-styrene block copolymer (SBS) with SEBS or / and SEPS, EVA or a polyolefin polymer.

[0068] 6. Hot melt adhesive composition according to any of the preceding statements, characterized in that the tackifier is selected from aliphatic, cycloaliphatic and aromatic hydrocarbon resins and their hydrogenated derivatives, rosin and rosin derivatives, terpenes and modified terpenes and mixtures thereof.

[0069] 7. Hot melt adhesive composition according to any of the preceding statements, characterized in that the tackifier is a fully hydrogenated hydrocarbon resin, a partially hydrogenated hydrocarbon resin, or a blend thereof.

[0070] 8. A hot melt adhesive composition according to statement 7, characterised in that the tackifier is a blend of a fully hydrogenated hydrocarbon resin and a partially hydrogenated hydrocarbon resin.

[0071] 9. The hot melt adhesive composition according to any of the preceding statements, characterized in that the tackifier resin is selected from one or more of the following categories:

[0072] i) hydrocarbon resins having C5 units; DCPD (dicyclopentadiene) hydrogenated resins; C9-modified DCPD hydrogenated resins; C9-modified hydrocarbon resins having C5 units; hydrogenated resins having C5 units;

[0073] ii) terpene resins;

[0074] iii) Partially hydrogenated C9 type aromatic resins.

[0075] 10. Hot-melt adhesive composition according to any of the preceding statements, characterized in that the first plasticizer P1 is a benzoate plasticizer comprising a cycloaliphatic or aromatic ester of phthalic acid, which is solid at room temperature.

[0076] 11. Hot-melt adhesive composition according to any of the preceding statements, characterized in that the first plasticizer P1 is a cycloaliphatic polyester of an aromatic carboxylic acid which is solid at room temperature.

[0077] 12. The hot-melt adhesive composition according to statement 10, characterized in that the plasticizer P1 is 1,4-cyclohexanedimethanol benzoate.

[0078] 13. Hot-melt adhesive composition according to any of the preceding statements, characterized in that the solid plasticizer P1 is present in an amount of 5% to 15% by weight, based on the total weight of the composition.

[0079] 14. Hot-melt adhesive composition according to any of the preceding statements, characterized in that the solid plasticizer P1 is present in an amount of 7% to 14% by weight, based on the total weight of the composition.

[0080] 15. Hot-melt adhesive composition according to any of the preceding statements, characterized in that the plasticizer P2 is contained in the adhesive composition in an amount of 0.1 to 10% by weight, based on the total weight of the adhesive composition.

[0081] 16. Hot-melt adhesive composition according to any of the preceding statements, characterized in that the plasticizer P2 is contained in the adhesive composition in an amount of 0.5 to 7% by weight, based on the total weight of the adhesive composition.

[0082] 17. Hot-melt adhesive composition according to any of the preceding statements, characterized in that the liquid plasticizer P2 is selected from naphthenic oils and / or paraffin oils.

[0083] 18. Hot-melt adhesive composition according to any of the preceding statements, characterized in that the plasticizer blend c) consists of plasticizers P1 and P2 and the composition does not contain any further plasticizers.

[0084] 19. A hot melt adhesive composition according to any of the preceding statements, characterised in that the composition is characterised by at least one of the following properties:

[0085] i) Opening time is 30 to 240 seconds;

[0086] ii) Temperature resistance range is -20 to 50°C;

[0087] 20. Use of a hot melt adhesive composition as defined in any one of statements 1 to 19 in paper packaging, preferably in an automated paper packaging production line.

[0088] 21. Use according to statement 20 for use in the production of safe paper packaging.

[0089] 22. An article comprising at least two layers adhered to each other with a hot melt adhesive composition as defined in any one of Statements 1 to 19.

[0090] 23. Article according to statement 22, characterized in that at least one of the layers comprises cellulose fibers.

[0091] 24. Article according to statement 22 or 23, characterised in that it is selected from: sealable paper bags, in particular those which can contain up to 2 kg; and secure paper packaging.

[0092] The present invention will be explained in more detail with reference to the following examples, which should by no means be construed as limiting the scope and spirit of the present invention. Example:

[0093] The following examples in Table 1 are preferred components and ranges for the compositions of the present invention. In all cases, no other components are present in the formulation other than those listed, so the total amount of the listed components is 100% by weight.

[0094] Table 1

[0095]

[0096] Table 2 shows the composition of an inventive adhesive composition according to the present invention compared with compositions falling outside the claimed composition range:

[0097] Table 2:

[0098] Function Example 1 Example 2 (Comparative Example) Mineral oil Plasticizer P2 4 3 1,4-Cyclohexanedimethanol benzoate Plasticizer P1 10 25 Phosphite Antioxidant Antioxidants 0.5 0.5 Triblock SIS block copolymer; Styrene content: 30% Block copolymers 25 26 Fully hydrogenated hydrocarbon resin Tackifier 24 21.5 Partially hydrogenated hydrocarbon resins Tackifier 36.5 24 total 100 100

[0099] The hot melt adhesive compositions were tested in various applications and their performance was compared with conventional hot melt adhesives. Technomelt EM 725 and Technomelt PS 5609 N from Henkel AG & Co. KGaA were used for comparison.

[0100] 1. Dynamic peel test

[0101] A 100 mm wide strip of paper was coated with a 18 mm wide strip of hot melt coating, and the hot melt adhesive coating weight was 100 gsm. Then a second 100 mm wide strip of paper was bonded with an open time of 60 s, 120 s or other specified time by compacting the second strip with a 2 kg roller. The bonded strip of 25 mm wide was cut transversely. Different speeds were used to peel off the samples. In the case of the composition of the present invention, the desired fiber tearing was observed. The results are summarized in Table 3.

[0102] Table 3a: Standard dense envelope paper 120g / m 2 ; 60s opening time

[0103]

[0104] Table 3b: Standard dense envelope paper 120g / m 2 ; 120s opening time

[0105]

[0106] Table 3c: Standard dense envelope paper 120g / m 2 ; 60s opening time

[0107]

[0108] Table 3d: Standard dense envelope paper 120g / m 2; 120s opening time

[0109]

[0110] 2. Static peel test

[0111] A 100 mm wide strip of paper is coated with a 18 mm wide strip of hot melt coating and the hot melt adhesive coating weight is 100 gsm. A second 100 mm wide strip of paper is then bonded with an open time of 60 s, 120 s or other specified time by pressing the second strip of paper with a 2 kg roller to form a bond. The bonded paper strips are cut 25 mm wide transversely. One end is hung on a test rig in an oven and a 100 g weight is placed on the other end in a 180° peeling manner. The static peel test is carried out in an environment with a temperature of 45°C and the time [hours] required for the weight to fall is recorded, which indicates the debonding of the paper strip. Standard dense envelope paper 120 g / m 2 The results are summarized in Table 4 and show that the adhesion of the composition of the present invention is significantly improved.

[0112] Table 4:

[0113]

[0114]

[0115] It will be appreciated that the invention can be modified within the scope of the appended claims.

Claims

1. A hot melt adhesive composition, wherein based on the total weight of the composition, the composition comprises: a) 10 to 60% by weight of a thermoplastic block copolymer, b) 30 to 70 wt % of a tackifier; and c) greater than 5 to 40% by weight of a plasticizer blend, It is characterized in that The plasticizer blend comprises: a first solid plasticizer P1 in an amount of 5 wt % to 16 wt % based on the total weight of the composition, and a second liquid plasticizer P2.

2. The hot melt adhesive composition according to claim 1, characterized in that The thermoplastic block copolymer is selected from ABA block copolymers, (AB)n or A-(BA)nBA block copolymers, wherein n is an integer of 1 or greater, each A comprises a polystyrene block and each B comprises a rubbery block.

3. The hot melt adhesive composition according to any one of the preceding claims, characterized in that The thermoplastic copolymer is styrene-isoprene-styrene copolymer (SIS), or a blend of SIS and styrene-butadiene-styrene block copolymer (SBS), or a blend of SIS and styrene-butadiene-styrene block copolymer (SBS) with SEBS or / and SEPS, EVA or polyolefin polymer.

4. The hot melt adhesive composition according to any one of the preceding claims, characterized in that The tackifier is selected from aliphatic, alicyclic and aromatic hydrocarbon resins and their hydrogenated derivatives, rosin and rosin derivatives, terpenes and modified terpenes and mixtures thereof.

5. The hot melt adhesive composition according to claim 4, characterized in that The tackifier resin is selected from one or more of the following categories: i) hydrocarbon resins having C5 units; DCPD (dicyclopentadiene) hydrogenated resins; C9-modified DCPD hydrogenated resins; C9-modified hydrocarbon resins having C5 units; hydrogenated resins having C5 units; ii) terpene resins; iii) Partially hydrogenated C9 type aromatic resins.

6. A hot melt adhesive composition according to any one of the preceding claims, characterized in that The first plasticizer P1 is a benzoate plasticizer containing an alicyclic or aromatic ester of phthalic acid, or an alicyclic polyester of an aromatic carboxylic acid, which is solid at room temperature.

7. The hot melt adhesive composition according to claim 6, characterized in that The plasticizer P1 is 1,4-cyclohexanedimethanol benzoate.

8. A hot melt adhesive composition according to any one of the preceding claims, characterized in that The plasticizer P2 is contained in the adhesive composition in an amount of 0.1 to 10 wt %, preferably 0.5 to 7 wt %, based on the total weight of the adhesive composition.

9. The hot melt adhesive composition according to any one of the preceding claims, characterized in that The liquid plasticizer P2 is selected from naphthenic oil and / or paraffin oil.

10. A hot melt adhesive composition according to any one of the preceding claims, characterized in that The composition is characterized by at least one of the following properties: i) an open time of 30 to 240 seconds, preferably 90 to 210 seconds; ii) Temperature resistance range is -20 to 50°C; 11. Use of the hot melt adhesive composition according to any one of claims 1 to 10 in paper packaging, preferably in an automated paper packaging production line.

12. Use according to claim 11 for producing safe paper packaging.

13. An article comprising at least two layers bonded to one another with a hot melt adhesive composition according to any one of claims 1 to 10.

14. The product according to claim 13, characterized in that At least one of the layers comprises cellulose fibers.

15. The product according to any one of claims 13 or 14, characterized in that The article is selected from: sealable paper bags, especially those that can hold up to 2 kg; and secure paper packaging.

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