Description:FIELD OF THE INVENTION
[0001] The present disclosure generally relates to a hot melt adhesive (HMA). In particular, the present invention relates to a hot melt adhesive composition based on C5 aliphatic and dicyclopentadiene (DCPD) hydrocarbon resin with polar and non-polar ethylene copolymers. The present invention also relates to a process for the preparation of hot melt adhesive compositions from polar and non-polar ethylene copolymers with hydrocarbon resins, polyethylene wax and additives.

BACKGROUND OF THE INVENTION
[0002] Hot melt adhesives are composed of thermoplastic materials, such as polyamides, polyolefins, polyesters, and ethylene-vinyl acetate (EVA). Hot melt adhesives are widely used in a variety of industries, such as packaging, woodworking, construction, and automotive manufacturing, for bonding a wide range of materials, including plastics, wood, metal, and textiles. Four primary components are used for formulating hot melt adhesives: (a) base polymer, (b) tackifier (hydrocarbon resin), (c) wax and (d) antioxidants.
[0003] Tackifier is the ingredient present in the highest proportion. Most of the resin types used in a hot melt adhesive are rosin and hydrogenated rosin, rosin ester, hydrogenated hydrocarbon, terpene phenolic, C5 & C10 hydrocarbon resins.
[0004] CN115109540A discloses a hot melt adhesive comprising of the following components in parts by weight: 30-60 parts of ethylene-vinyl acetate copolymer, 10-20 parts of acrylic copolymer, 0.3-2 parts of epoxy compatilizer, 20-45 parts of tackifier, 1-5 parts of viscosity regulator, 5-15 parts of toughening agent and 0.5-5 parts of hindered phenol antioxidant.
[0005] CN101883831B relates to hot melt adhesives composition that includes a first tackifying agent that includes phenol-modified aromatic hydrocarbon resin, thermoplastic polymer that includes ethylene copolymer, and a first wax.
[0006] The need for premium hot-melt adhesives is being driven by the increasing use of intelligent, sustainable and consumer-based packaging solutions. To lessen their carbon impact, paper packaging is becoming more and more common. Customized wrapping is also becoming more and more popular, and the market for pre-packaged goods and beverages is expanding. Moreover, the packaging sector employs delicate materials for wrapping applications, including cardboard, paper, cartons, and plastics. Low-temperature hot-melt adhesives are required for the effective bonding of these sensitive components. Low-temperature hot-melt adhesives come highly recommended since they are economical, energy-efficient, and help keep manufacturing equipment in good condition for less money in maintenance expenditures. The present hot melt adhesive will be the most promising solution to use as a packaging and paper converting adhesive designed for bonding well to porous substrates, this adhesive will be best for use in moderate temperature ranges and where minimum flexibility is required.
[0007] Therefore, there is an unmet need in the art to provide a new hot melt adhesive composition having enhanced adhesion; good SAFT and Lap shear strength and low viscosity.

OBJECTIVES OF THE INVENTION
[0008] An objective of the present invention is to provide a hot melt adhesive composition having enhanced adhesion.
[0009] Another objective of the present invention is to provide a process of preparation of hot melt adhesive.
[0010] Yet another objective of the present invention is to provide a hot melt adhesive having C5-aliphatic and dicyclopentadiene (DCPD) hydrocarbon resin tackifier with polar and non-polar ethylene copolymers.

SUMMARY OF THE INVENTION
[0011] The present invention relates to a hot melt adhesive composition based on C5, and dicyclopentadiene (DCPD) hydrocarbon resins with polar and non-polar ethylene copolymers. The present invention also relates to a process for preparation of hot melt adhesives from polar and non-polar ethylene copolymers with hydrocarbon resins.
[0012] In one aspect, the present invention relates to a hot melt adhesive composition comprising:
(a) ethylene copolymers in an amount ranges from 5% to 90 % by weight of the composition;
(b) hydrocarbon resins in an amount ranges from 10% to 75 % by weight of the composition;
(c) polyethylene wax in an amount ranges from 1% to 20% by weight of the composition; and
(d) antioxidants in an amount ranges from 0.1% to 1 wt% by weight of the composition.
[0013] In another aspect, the present invention relates to a process the preparation of hot melt adhesive comprising the steps of:
(a) dry blending the HMA composition of present invention in mixer to obtain a blended HMA composition,
(b) melt mixing the blended HMA composition at a temperature in a range of 150?C to 200?C to obtain homogeneous hot melt adhesive compositions,
(c) extruding the homogeneous hot melt adhesive composition in extruder and/or rheomixer to obtain small HMA granules, and
(d) injection molding the small HMA granules into different article for evaluation.

DETAILED DESCRIPTION OF THE INVENTION
[0014] The following is a detailed description of embodiments of the disclosure. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0015] Unless the context requires otherwise, throughout the specification, which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”
[0016] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
[0017] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0018] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0019] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Not with standing that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable.
[0020] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.
[0021] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
[0022] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.
[0023] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0024] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description that follows, and the embodiments described herein, is provided by way of illustration of an example, or examples, of particular embodiments of the principles and aspects of the present disclosure. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the disclosure.
[0025] It should also be appreciated that the present invention can be implemented in numerous ways, including as a system, a method or a device. In this specification, these implementations, or any other form that the invention may take, may be referred to as processes. In general, the order of the steps of the disclosed processes may be altered within the scope of the invention.
[0026] The present invention relates to a hot melt adhesive composition based on hydrocarbon resins with polar and non-polar ethylene copolymers. The present invention also relates to a method of preparation of hot melt adhesives from polar and non-polar ethylene copolymers with hydrocarbon resins.
[0027] In an embodiment, the present invention relates to a hot melt adhesive composition comprising:
(a) ethylene copolymer in an amount ranges from 5% to 90 % by weight of the composition;
(b) hydrocarbon resin in an amount ranges from 10% to 75 % by weight of the composition;
(c) polyethylene wax in an amount ranges from 1% to 20 % by weight of the composition; and
(d) antioxidant in an amount ranges from 0.1% to 1 wt% by weight of the composition.
[0028] In another embodiment of the present invention, the ethylene copolymers can be polar and non-polar ethylene copolymers.
[0029] In another embodiment of the present invention, the ethylene copolymer is selected from ethylene butyl acrylate copolymer, ethylene hexane copolymer, maleated polypropylene, ethylene 1-hexene copolymer, ethylene 1-decene copolymer, ethylene 1-octane copolymer, & ethylene methyl acrylate copolymer. Preferably, the ethylene copolymer is selected from ethylene butyl acrylate copolymer, ethylene methyl acrylate copolymer, ethylene hexane copolymer, 2-Ethyl hexyl acrylate copolymer or maleated polypropylene.
[0030] In another embodiment of the present invention, the hydrocarbon resin is selected from C5 aliphatic and dicyclopentadiene (DCPD) hydrocarbon resins. Preferably, the resin is dicyclopentadiene (DCPD) hydrocarbon resin.
[0031] The C5 aliphatic hydrocarbon resin is selected from any of the relatively polar and nonpolar types. Preferred resins include aliphatic petroleum hydrocarbon resins examples of which are based on C5 olefins having softening point of 95-115°C as per ASTM D 6090 and Molecular weight of 1000-1200 g/mol.
[0032] The dicyclopentadiene (DCPD) hydrocarbon resin is a resin having a molecular weight ranging from 700 to 4000 g/mol. Preferably, MW ? 700 g/mol and more preferably not more than MW ? 1500 g/mol. The Ring & Ball Softening Point, as determined by ASTM E-28, of the dicyclopentadiene (DCPD) hydrocarbon resin should be greater than 70°C, preferably greater than 80°C and more preferably greater than 90°C, but not more than 140°C and most preferably not more than 125°C.
[0033] In another embodiment of the present invention, the antioxidant is hindered phenol based antioxidant. A particularly preferred antioxidant is primary antioxidant, a tetrakis (methylene(3,5-di-teri-butyl-4-hydroxyhydrocinnamate)) methane.
[0034] In yet another embodiment of the present invention, ratio of total tackifier to ethylene copolymer may be, for example, from about 70:30 to 30:70, and preferably from 60:40 to 40:60.
[0035] In another embodiment, the present invention relates to a hot melt adhesive composition comprising:
(a) ethylene copolymer in an amount ranges from 25% to 50 wt% by weight of the composition;
(b) hydrocarbon resin in an amount ranges from 35% to 60 wt% by weight of the composition;
(c) polyethylene wax in an amount ranges from 10% to 15 wt% by weight of the composition; and
(d) antioxidant in an amount ranges from 0.1% to 0.5 wt% by weight of the composition.
[0036] In another embodiment, the present invention relates to a hot melt adhesive composition comprising:
(a) ethylene copolymer in an amount of about 35-50 wt% by weight of the composition;
(b) hydrocarbon resin in an amount of about 35 - 50 wt% by weight of the composition;
(c) polyethylene wax in an amount of about 12- 15 wt % by weight of the composition; and
(d) antioxidant in an amount of about 0.2 – 0.5 wt% by weight of the composition.
[0037] In another embodiment, the present invention relates to a hot melt adhesive composition comprising:
(a) ethylene copolymer in an amount ranges from 5% to 75 wt% by weight of the composition;
(b) dicyclopentadiene (DCPD) hydrocarbon resin in an amount ranges from 10% to 60 % by weight of the composition;
(c) polyethylene wax in an amount ranges from 5% to 20 wt% by weight of the composition; and
(d) antioxidant in an amount ranges from 0.1% to 1 wt% by weight of the composition.
[0038] In another embodiment, the present invention relates to a process for the preparation of the hot melt adhesive composition comprising the step of dry blending the ethylene copolymers, hydrocarbon resins, polyethylene wax and antioxidant at a temperature in a range of 150?C to 200?C to obtain homogeneous mixture of molten hot melt adhesive consists of the following steps
[0039] In another embodiment, the present invention relates to a process for the preparation of hot melt adhesive comprising the steps of:
(a) dry blending the HMA composition of present invention in mixer to obtain blended HMA composition;
(b) melt mixing the blended HMA composition at a temperature in a range of 150?C to 200?C in an extruder / rheomixer to obtain homogeneous hot melt adhesive compositions.
(c) extruding the homogeneous hot melt adhesive composition in extruder and/or rheomixer to obtain the small HMA granules, and
(d) injection molding the small HMA granules to obtain the hot melt adhesive sample for testing & application.
[0040] In another embodiment, the present invention relates to a process for the preparation of hot melt adhesive comprising the steps of:
(a) dry blending of hot melt adhesive composition of the present invention in mixer to obtain a HMA mixture,
(b) melt mixing of the HMA mixture at a temperature in a range of 150?C to 200?C in an extruder / rheomixer to obtain homogeneous hot melt adhesive mixture.
(c) extruding the homogeneous hot melt adhesive mixture in the form of small HMA granules.
(d) injection molding the small HMA granules into different article to obtain hot melt adhesive.
[0041] In another embodiment of the present invention, the temperature of blending the components is in range of 170?C to 200?C. Preferably, the temperature is 180?C and most preferably 170oC.
[0042] In another embodiment, the present relates to a process of preparing hot melt adhesive in torque Rheometer, wherein the process comprising the steps of:
(a) dry blending the Hot Melt Adhesive (HMAs) compositions as claimed in any one of the claims 1 to 7 in high-speed mixer followed by melt mixing in torque rheometer with a screw speed of 50 RPM, at a temperature of 170°C for 10-15 minutes to obtain extrudates;
(b) cooling the extrudates to obtain small granules; and
(c) injection molding the small granules into standard test specimens on micro-compounder to obtain the melt adhesive.
[0043] In another embodiment, the present invention relates to a process of preparing hot melt adhesive in micro compounder, wherein the process comprising the steps of:
(a) dry blending the Hot Melt Adhesive (HMAs) compositions as claimed in any one of the claims 1 to 7 in high-speed mixer to obtain homogenous HMA mixture;
(b) melt mixing the homogenous HMA mixture in twin screw micro compounder with a screw speed of 50 RPM, at a temperature of 170°C to obtain a extrudates;
(c) cooling the extrudates to obtain a small HMA granules; and
(d) injection molding the small HMAs granules into standard test specimens on micro-compounder to obtain the hot melt adhesive.
[0044] In another embodiment of the present invention, the hot melt adhesives (HMAs) made using DCPD resin of the present invention showed better shear adhesion failure temperature, Lap shear strength, T-Peel strength compared with HMAs made using C5 aliphatic & dicyclopentadiene hydrocarbon resins while retaining most of the other properties.
[0045] In another embodiment of the present invention, the HMAs made using DCPD resin showed excellent thermal stability at application temperature due to crosslinking of unsaturated bond present in the structure.
[0046] In another embodiment, the hot melt adhesive composition of the present invention showed excellent thermal stability as measured by SAFT test. The C5-LMW & C5-HSP having an 50% hydrocarbon resin showed SAFT of 95°C, while DCPD hydrocarbon resin with 50% loading showed 105°C SAFT stability.
[0047] In another embodiment, the hot melt adhesives of the present invention prepared using dicyclopentadiene resin showed better mechanical properties, adhesion when tested against 3ply cardboards, metal – metal surface at room temperature and subzero temperatures.
[0048] In another embodiment, the hot melt adhesives of the present invention showed highest SAFT of 118°C for composition containing combination of ethylene copolymer with C5 hydrocarbon resin maintaining other properties same.
EXAMPLES
Materials:
[0049] (a) Random ethylene-butyl acrylate copolymer having a 28% acrylate content, the MFI of 175 g/10min (190°C/2.16kg) & melting point of 75°C as per ISO 11357-3 (b) Random ethylene-butyl acrylate copolymer having a 35% acrylate content, the MFI of 320 g/10min (190°C/2.16kg) & melting point of 90°C as per ISO 11357-3. (c) Primary antioxidant: Hindered phenol based primary antioxidant supplied by Sigma Aldrich. (d) PE wax was procured having a melting point of 100 + 5 as per ASTM D 3418 (e) DCPD hydrocarbon resin was prepared through cationic polymerization using Lewis acid as a catalyst in house. The softening point of the DCPD resin obtained was in the range from 40-80 °C, preferably, 40-50 °C. The molecular weight (Mw) of the prepared DCPD hydrocarbon resin-1 is in the range of 600-2000 g/mol, preferably 600-1000 g/mol. The molecular weight (Mw) of the prepared DCPD hydrocarbon resin-2 is in the range of 2000-4000 g/mol, preferably 3000-4000 g/mol (f). C5 (C5-HSP) aliphatic hydrocarbon resin with a softening point of 115°C and a molten Gardner color of 4. The molecular weight (Mw) of the C5 aliphatic hydrocarbon resin is in the range of 900-1500 g/mol, preferably 900-1200 g/mol. (g) Another low molecular weight C5 (C5-LMW) aliphatic hydrocarbon resin softening point of 99°C as per ASTM E28 and a molten Gardner color of 4.
Evaluation of physico-Mechanical & Thermal Properties of Hot Melt Adhesives
1. Melt Viscosity: The melt viscosity of Hot Melt Adhesives (HMAs) granules were measured @ 120 °C (Pa.s) as per ASTM D 3236
2. Mechanical Properties: Mechanical properties such as Tensile strength and other properties of injection molded HMA samples were measured as per ASTM D-638.
3. Thermal Properties: Thermal properties such as Melting Temperature (T m), Crystallization Temperature (Tc), Softening Temperature etc measured on Differential Scanning Calorimeter as per ASTM D 3418.
4. Density: The density of HMAs granules were measured as per ASTM D- 792 (23°C)
5. Shore D A Hardness: The Shore D hardness of injection molded samples of HMAs were measured as per ASTM D-2240
6. Open Time and Set Time: Open time and set time were measured as per ASTM D-4497
7. Lap Shear Strength (LSS): Lap Shear Strength on Kraft Paper & Metal to metal at RT/Sub zero for the prepared HMAs were measured as per ASTM D – 1002
8. T – Peel Strength & Maximum Peel Load: T – Peel strength & Maximum Peel Load on Kraft paper using prepared HMAs were measured as per ASTM D – 1876-08
9. SAFT Test: SAFT test for metal – metal at Sub zero & RT were measured as per ASTM D- 4498 & ASTM D-4499 respectively.
Examples 1 – 22
Process for the preparation of Hot Melt Adhesive compositions
Procedure 1:
The Hot Melt Adhesive (HMAs) compositions having different concentration of ethylene copolymers (5-90 wt.%), Hydrocarbon Resins (10 - 75 wt.%), polyethylene wax (1-20 wt.%) & Antioxidants (0.1-1 wt.%) were made by dry blending in high-speed mixer followed by melt mixing in Torque rheometer. The melt mixing of HMAs was carried out in Torque rheometer with a screw speed of 50 RPM, at a temperature of 170°C for 10-15min. The extrudates were cooled and made into small granules. The melt mixed HMAs granules were Injection Molded into standard test specimens on micro-compounder and evaluated for their physical, mechanical, thermal & adhesion properties.
Procedure 2:
The Hot Melt Adhesive (HMAs) compositions having different concentration of ethylene copolymers (5-90 wt.%), Hydrocarbon Resins (10 - 75 wt.%), polyethylene wax (1-20 wt.%) & Antioxidants (0.1-1 wt.%) were made by dry blending in high-speed mixer followed by melt mixing in twin screw micro compounder. The melt mixing of HMAs was carried out in twin screw micro compounder with a screw speed of 50 RPM, at a temperature of 170°C. The extrudates were cooled and made into small granules. The melt mixed HMAs granules were Injection Molded into standard test specimens on micro-compounder and evaluated for their physical, mechanical, thermal & adhesion properties. Details of various compositions for Examples 1 – 22 are given in Table 1, 2 & 3.
Table 1: Hot Melt Adhesive compositions for Examples 1 – 10
Sr. No. Examples 1 2 3 4 5 6 7 8 9 10
1 Ethylene Acrylate copolymer (28%) 75 60 35 10 - - - - - -
2 Ethylene Acrylate copolymer (35%) - - - - 75 60 35 75 60 35
4 Hydrocarbon Resin (C5-HSP) 10 25 50 75 10 25 50 - - -
5 Hydrocarbon Resin (C5-LMW) - - - - - - - 10 25 50
6 PE wax 14.8 14.8 14.8 14.8 14.8 14.8 14.8 14.8 14.8 14.8
7 Primary Antioxidant 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2

Table 2: Hot Melt Adhesive compositions for Examples 11-20
Sr. No. Examples 11 12 13 14 15 16 17 18 19 20
1 Ethylene crylate copolymer (28%) 75 60 35 10 - - - 75 60 35
2 Ethylene crylate copolymer (35%) - - - - 75 60 35 - - -
3 DCPD Hydrocarbon Resin -1 (Mw: 600-1200 g/mol) 10 25 50 75 10 25 50 - - -
4 DCPD Hydrocarbon Resin -2
(Mw: 3000-4000 g/mol) - - - - - - - 10 25 50
5 PE wax 14.8 14.8 14.8 14.8 14.8 14.8 14.8 14.8 14.8 14.8
6 Primary Antioxidant 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2

Table 3: Hot Melt Adhesive compositions for Examples 21 – 22
Sr. No. Examples 21 22
1 Ethylene Acrylate copolymer (28%) 17.5 23.33
2 Ethylene hexene Copolymer 17.5 11.66
3 Hydrocarbon Resin (C5-LMW) 50 50
4 PE wax 14.8 14.8
5 Primary Antioxidant 0.2 0.2

Evaluation of Physical & Thermo-Mechanical Properties for prepared hot melt adhesives:
[0050] The physical properties such as melt Viscosity, Density, Open Time, Set Time, Thermal properties such as Melting Temperature, Crystallization temperature and Mechanical Properties such as Tensile strength, Shore D hardness, Lap shear strength (LSS) Strength, T – Peel Strength, Maximum Peel Load and Shear adhesion failure temperature (SAFT) test were measured as per ASTM test methods as detailed above.
Physical and Mechanical Properties of prepared hot melt adhesives
Physical Properties and Mechanical Properties of the Hot Melt Adhesive composition of the present invention are given in Table 4 & Table 5 for example 1-22. Addition of C5-LMW, C5-HSP and DCPD based hydrocarbon resin helped in reducing the viscosity of the hot melt adhesive system for fast packaging applications. The reduced viscosity is advantageous in terms of more coverage & faster application of adhesive at higher temp. From the Melting temp & crystallization it was observed that, there is no effect on the melting temp by using above hydrocarbon resin mentioned in the example of 1-22.

Table 4: Physical, Thermal & Rheological Properties of prepared Hot Melt Adhesives
Sr. No. Examples 1 2 3 4 5 6 7 8 9
1 Melt Viscosity @ 120 °C (Pa.s) 199 127 18 12 68 35 10 83 51
2 Melting Temp (°C) 100 96 96 100 99 96 89 99 96
3 Crystallization Temp (°C) 86 86 82 79 88 86 86 87 89
4 Density (g/ m-3) 0.783 0.796 0.857 - 0.924 0.938 0.958 - -

Table 5: Physical, Thermal & Rheological Properties of prepared Hot Melt Adhesives
Sr. No. Examples 10 11 12 13 14 15 16 17
1 Melt Viscosity @ 120 °C (Pa.s) 16 199 55 14 Brittle 87 37 14
2 Melting Temp (°C) 94 101 101 98 NA 100 103 93
3 Crystallization Temp (°C) 89 89 89 88 NA 89 89 88
4 Density (g/ m-3) 0.857 0.923 0.940 0.971 NA 0.924 0.952 0.975

Table 6: Physical, Thermal & Rheological Properties of prepared Hot Melt Adhesives
Sr. No Examples 18 19 20 21 22
1 Melt Viscosity @ 120 °C (Pa.s) 268 212 1009 93.6 102.5
2 Melting Temp (°C) 102 102 101 119 121
3 Crystallization Temp (°C) 91 90 89 105 105

The mechanical properties of the hot melt adhesives prepared using different hydrocarbon resins and ethylene copolymers given in Table 7 & 8 shows not much difference in their properties when tested on 3 ply cardboard paper.
Table 7: Mechanical Properties of prepared Hot Melt Adhesive on 3ply cardboard paper
Sr. No. Examples 1 2 3 4 5 6 7 8 9 10
1 Tensile Strength, (Mpa) 2.9 2.6 3.7 BF - - - 3.10 3.09 5.3
2 SHORE – D 21 20 19 - 22 23 23 20 21 22
BF: Brittle Fracture
Table 8: Mechanical Properties of prepared Hot Melt Adhesive on 3ply cardboard paper
Sr. No. Examples 11 12 13 14 15 16 17 18 19 20 21 22
1 Tensile Strength, (Mpa) 4.18 3.7 3.02 BF 3.1 2.7 2.4 4.51 3.8 3.04 4.8 5.1
2 SHORE – D 21.2 20.2 19.4 NA 19 19 22 - - - 25 28
BF: Brittle Fracture
From the data shown in above examples, it is indicated that brittle fracture (BF) is observed in some cases where the higher content of hydrocarbon resin is used in the formulation. So it is clear that higher content of hydrocarbon resin is not desirable in term of mechanical strength.
Also, from data shown in Table 7 & 8, it is clear indicated that the mechanical strength of prepared hot melt adhesive is observed on higher side when DCPD hydrocarbon resin is used compared to C5-HSP & C5-LMW hydrocarbon resin (Example 11-20). Highest mechanical strength is observed for prepared hot melt adhesive with a combination of ethylene acrylate copolymer, ethylene hexane copolymer & C5-LMW in the formulation.
Open time & set time test for the prepared hot melt adhesives:
[0051] The open time & set time of the prepared hot melt adhesives were measured according to market practice. The open time & set time is the basic characteristics of the melt adhesive, which gives an idea for suitability of application as given in Tables 9-11. The open time obtained for DCPD hydrocarbon resin based hot melt adhesives are more than the C5 hydrocarbon resin, which allows more time and better in application. The set time of all compositions is observed similar with the C5-HSP & C5-LMW hydrocarbon resin sample which indicates there is an advantage of adding DCPD hydrocarbon resin combination with ethylene acrylate copolymer.

Table 9: Open Time and Set Time for the prepared Hot Melt Adhesives
Sr. No. Examples 1 2 3 4 5 6 7
1 Set Time (Sec) 3 3 3 NM 3 3 3
2 Open Time (Sec) 10-12 10-14 5-10 5-10 12-15 18-21 20-24
NM: Not measurable
Table 10: Open Time and Set Time for the prepared Hot Melt Adhesives
Sr. No. Examples 8 9 10 11 12 13 14 15 16
1 Set Time (Sec) 3 3 3 3 3 3 NM 3 3
2 Open Time (Sec) 18-22 25-30 31-48 8-12 8-13 9-15 NM 7-101 12-14
NM: Not measurable
Table 11: Open Time and Set Time for the prepared Hot Melt Adhesives
Sr. No Examples 17 18 19 20 21 22
1 Set Time (Sec) 3 3 3 3 3 3
2 Open Time (Sec) 15-18 14-23 12-18 10-16 16-17 16-18
NM: Not measurable
The more open time is seen for example nos. 16-20 in which DCPD based hydrocarbon resin is used and having an open time more than 12 sec. This kind of HMA is suitable for application where more time is needed for application on substrate, specially, for large surface area substrate. The open time more than 15 sec is seen in case of combination of two copolymer and C5-LMW hydrocarbon resin is used.

Lap shear & T-peel adhesion test on 3ply cardboard paper:
[0052] The lap shear strength & T – Peel Strength was performed on a cardboard paper for actual application replication of strength as given in Tables 12 & 13. The lap shear strength data showed a similar trend of strength for all hydrocarbon resin. There is no adverse effect was observed with the addition of DCPD based hydrocarbon resin. T-peel strength is also found similar for all compositions. All examples showed a substrate failure (SF) which indicates the adhesive strength is more than the substrate strength, expect, the examples 4 & 14 due to higher amount of hydrocarbon resin in the formulation.
Table 12: Lap shear strength & T-peel strength of prepared hot melt adhesives on 3ply carboard paper
Sr. No Examples 1 2 3 4 5 6 7 8 9 10 11
1 LSS Strength on kraft (Mpa) SF SF SF SF - - - SF SF SF SF
2 T-Peel Strength on kraft (Mpa) 0.9 0.88 0.86 AF 1.4 1.05 1.03 1.3 1.3 1.6 0.986
3 Maximum Peel Load, (N) 22 22 21.6 AF 35.5 26.7 26.1 28 28 35 29.2
AF: Adhesive Failure, SF: Substrates Failure
Table 13: Lap shear strength & T-peel strength of prepared hot melt adhesives on 3ply carboard paper
Sr. No. Examples 12 13 14 15 16 17 18 19 20 21 22
1 LSS Strength on kraft (Mpa) SF SF SF SF SF SF SF SF SF SF SF
2 T-Peel Strength on kraft (Mpa) 0.696 0.445 BF 2.14 1.85 2.01 0.75 1.08 0.63 2.8 3.4
3 Maximum Peel Load, (N) 23.41 2.3 NM 54.3 47.1 51.1 19.2 27.3 15.9 61.3 69.1
BF – Brittle Fracture, SF: Substrates Failure
Lap shear adhesion strength tests for metal – metal was also performed hot melt adhesives after conditioning them at subzero & RT for 24hr. The results given in Table 14 & 15 indicated that in Examples 5, 8, 9, 10, 11, 16 & 17 containing C5-HSP, C5-LMW and dicyclopentadiene hydrocarbon resin have better adhesion strength when used with ethylene acrylate copolymer.
Table 14: Lap Shear Strength of prepared Hot Melt Adhesives
Sr. No Examples 1 2 3 5 8 9 10
1 LSS on Metal-metal (Mpa)- RT 0.47 0.56 0.65 2.16 1.92 1.85 1.05

Table 15: Lap Shear Strength of prepared Hot Melt Adhesives
Sr. No Examples 11 12 13 14 15 16 17 21 22
1 LSS on Metal-metal (Mpa)- RT 1.62 0.206 0.243 NM 0.27 1.6 1.1 3.2 3.1
BF – Brittle Fracture, SF: Substrates Failure, NM: Not measurable
Shear adhesion failure temperature (SAFT) test on 3ply cardboard paper:
The SAFT tests were performed after condition the prepared samples at subzero & RT for 24hr and results given in the tables 16 & 17 indicated higher values when DCPD hydrocarbon resin was used compared to C5 hydrocarbon resin.
Table 16: SAFT test results of prepared hot melt adhesives after conditioning at RT & Subzero Temp with a constant load
Sr. No. Examples 1 2 3 5 6 7 8 9 10
1 SAFT @ Sub Zero Temp (°C) 103 102 95 101 95 95 101 96 90
2 SAFT @ Room Temp (°C) 105 102 95 102 100 91 101 95 86

Table 17: SAFT test results of prepared hot melt adhesives after conditioning at RT & Subzero Temp with a constant load
Sr. No. Examples 11 12 13 14 15 16 17 21 22
1 SAFT @ Sub Zero Temp (°C) 105 105 101 NM 105 102 96 118 119
2 SAFT @ Room Temp (°C) 105 103 100 NM 103 100 96 118 100
NM: Not measurable
Examples 11, 12, 13, and 15 show better SAFT result in which the DCPD hydrocarbon resin is used as a tackifier with ethylene acrylate copolymer for preparation of HMA. The highest SAFT value is obtained for Examples 21 & 22 which is 118 & 119°C respectively. This indicated that the formulation containing combination of ethylene copolymer with C5 hydrocarbon resin gives excellent shear adhesion failure test results directly indicates the highest thermal stability.
[0053] The prepared hot melt adhesives, especially based on dicyclopentadiene hydrocarbon resin showed enhanced adhesion to substrates such as, cardboard, paper. The prepared hot melt adhesives have good elevated temperature properties such as SAFT, Lap shear strength, lower viscosity compared to hot melt adhesives made with C5 hydrocarbon resins. The DCPD hydrocarbon resin enhance the thermal stability of ethylene acrylate based hot melt adhesive as observed from above results shown in the tables 16 & 17.

ADVANTGAES OF THE INVENTION
• The present invention provides HMAs using DCPD resin that showed better shear adhesion failure temperature, Lap shear strength, T-Peel strength compared with HMAs made using commercial HC resins while retaining most of the other properties.
• The present invention provides HMAs using DCPD resin that showed excellent thermal stability at application temperature due to crosslinking of unsaturation bond present in the structure.
, Claims:1. A hot melt adhesive compositions comprising:
(a) ethylene copolymer in an amount ranges from 5% to 90 % by weight of the composition;
(b) hydrocarbon resin in an amount ranges from 10% to 75 % by weight of the composition;
(c) polyethylene wax in an amount ranges from 1% to 20 % by weight of the composition; and
(d) antioxidant in an amount ranges from 0.1% to 1 wt% by weight of the composition.
2. The hot melt adhesive composition as claimed in claim 1, wherein ethylene copolymers is selected from ethylene butyl acrylate copolymer, ethylene 1-hexene copolymer, maleated polypropylene, ethylene 1-decene copolymer, ethylene 1-octene copolymer, and ethylene methyl acrylate copolymer.
3. The hot melt adhesive composition as claimed in claim 1, wherein the hydrocarbon resin is C5-aliphatic resin and dicyclopentadiene (DCPD) resin.
4. The hot melt adhesive composition as claimed in claim 1, wherein the hydrocarbon resin is dicyclopentadiene (DCPD) resin.
5. The hot melt adhesive composition as claimed in claim 1, wherein the antioxidant is hindered phenol based primary antioxidant.
6. The hot melt adhesive composition as claimed in claim 1, wherein the ethylene copolymer and hydrocarbon resin is present in a ratio ranges from 70:30 to 30:70.
7. The hot melt adhesive composition as claimed in claim 1, wherein the composition comprises:
(a) ethylene copolymer in an amount ranges from 25% to 50 % by weight of the composition;
(b) hydrocarbon resin in an amount ranges from 35% to 50 % by weight of the composition;
(c) polyethylene wax in an amount ranges from 10% to 15 % by weight of the composition; and
(d) antioxidant in an amount ranges from 0.1% to 0.5 wt% by weight of the composition.
8. A process of preparing hot melt adhesive in torque rheometer, wherein the process comprising the steps of:
(a) dry blending the hot melt adhesive (HMAs) compositions as claimed in any one of the claims 1 to 7 in high-speed mixer followed by melt mixing in torque rheometer with a screw speed of 50 RPM, at a temperature of 170°C for 10-15 minutes to obtain extrudates;
(b) cooling the extrudates to obtain small HMA granules; and
(c) injection molding the small HMA granules into standard test specimens on micro-compounder to obtain the melt adhesive.
9. A process of preparing hot melt adhesive in micro compounder, wherein the process comprising the steps of:
(a) dry blending the hot melt adhesive (HMAs) compositions as claimed in any one of the claims 1 to 7 in high-speed mixer to obtain homogenous HMA mixture;
(b) melt mixing the homogenous HMA mixture in twin screw micro compounder with a screw speed of 50 RPM, at a temperature of 170°C to obtain a extrudates;
(c) cooling the extrudates to obtain a small HMA granules; and
(d) injection molding the small HMAs granules into standard test specimens on micro-compounder to obtain the hot melt adhesive.
10. The process as claimed in claim 8 or 9, wherein the hot melt adhesive is in a form of dumb bell, bars, and films.