Spreadable hybrid woodworking adhesive composition

Abstract

Disclosed is a spreadable hybrid woodworking adhesive composition. The spreadable hybrid woodworking adhesive composition comprises of a silylated polymer, at least one plasticizer, at least one pigment particle, an antioxidant, at least one filler, and one or more additives. This composition enhances bonding performance, offers superior moisture resistance, and ensures ease of application, making it ideal for woodworking applications.

Description

[0001] TITLE OF INVENTION: SPREADABLE HYBRID WOODWORKING ADHESIVE COMPOSITION CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY The present application claims priority from the Indian patent application having application number 202421045130 filed on 11thJune 2024, incorporated herein by a reference. TECHNICAL FIELD OF THE INVENTION The present invention relates to the field of bonding technologies. Particularly, the present invention relates to woodworking adhesive composition. BACKGROUND OF THE INVENTION Woodworking has undergone significant advancements with time, particularly in the production of plywood and furniture, where wood glue plays a vital role in ensuring strong, durable bonds. Historically, adhesives used in these applications were predominantly based on formaldehyde-urea resins due to their cost-effectiveness and bonding strength. However, the widespread use of formaldehyde-urea adhesives has raised concerns due to the release of formalin (a toxic form of formaldehyde) during the manufacturing process. This volatile organic compound (VOC) can be emitted as a gas, posing potential health risks such as respiratory issues, skin irritation, and long- term exposure leading to cancer. Among the alternatives, polyvinyl acetate (PVAc) and rubber-based adhesives have gained prominence due to their ease of application and moderate bonding properties. However, these formulations present several drawbacks. PVAc adhesives are susceptible to water and heat exposure, limiting their application in moisture-prone environments or structural uses requiring enhanced durability. Furthermore, they often contribute to warping, bubble formation, and delamination, which negatively impact the overall quality and longevity of the bonded materials. Additionally, the application process for PVAc and rubber-based adhesives typically requires prolonged surface pressure and the use of auxiliary materials like masking tape, resulting in inefficiencies and suboptimal finishing. To overcome these limitations, extensive research has been conducted on alternative adhesive compositions that offer improved performance characteristics. Hybrid polymer-based adhesives have emerged as a promising solution, combining the flexibility of elastomers with the strength of thermosetting resins. These adhesives demonstrate excellent bonding to a variety of substrates while providing superior resistance to environmental stressors such as humidity and temperature variations. Their ability to cure under ambient conditions without releasing harmful byproducts makes them a preferred choice for modern applications. Hybrid polymers, particularly those modified with silane groups, have shown promise in addressing the limitations of conventional adhesives. Silane-modified adhesives exhibit superior adhesion, reduced curing times, and enhanced mechanical properties, making them suitable for both indoor and outdoor applications. The incorporation of reactive silane groups allows for improved crosslinking density, which contributes to increased water and heat resistance, crucial for structural applications. These formulations also reduce the risk of warping and delamination, ensuring long-term durability and aesthetic integrity. Recent patent literature highlights various approaches in the development of high-performance adhesives. Indian patent application IN202017030821 discloses a room-temperature curable adhesive composition incorporating silyl-modified polyether, silyl-modified polyurethane, or silyl-terminated polyacrylate. This formulation offers moldability and strong adhesion without requiring extensive curing times. Similarly, CN105111991 describes a silane-modified polyether sealant that demonstrates moisture-curing properties while preventing bubble formation, ensuring strong adhesion across diverse substrates such as wood, metals, and glass. Additionally, EP2162479A1 introduces a moisture-curable polymer system for bonding floor coverings, leveraging polyether-terminated reactive silane groups to achieve robust adhesion and longevity. Despite these advancements, challenges remain in developing hybrid adhesives with superior spreadability, enhanced initial tack, and high durability without compromising ease of application. While existing formulations provide improvements in certain areas, they still require further optimization to achieve balanced properties. Current research focuses on enhancing flowability and uniform adhesion, reducing viscosity fluctuations, and increasing open time to accommodate different application conditions. Furthermore, advancements in catalyst systems and polymer architecture are being explored to fine-tune curing kinetics and adhesion performance. Therefore, there remains an unmet need for spreadable, flowable hybrid adhesives that not only overcome the limitations of polyvinyl acetate (PVAc) and rubber-based adhesives but also provide strong initial contact, improved adhesion, high resistance to heat and water, and reduced reliance on additional tools such as masking tape while ensuring enhanced aesthetic results. SUMMARY OF THE INVENTION As disclosed herein, the present subject matter relates to a spreadable hybrid woodworking adhesive composition. It was surprisingly found that a spreadable hybrid wood working adhesive of the present invention exhibit optimum viscosity, density, and spreadability, water resistance, workability, moisture resistance, and bonding strength. In an aspect of the present invention, a spreadable hybrid woodworking adhesive composition is disclosed. The composition comprises a silylated polymer in an amount in the range of 10 wt. % to 60 wt. % with respect to the total weight of the woodworking adhesive composition. The composition comprises at least one plasticizer in an amount in the range of 5 wt. % to 30 wt.% with respect to the total weight of the woodworking adhesive composition. The composition comprises at least one filler in an amount in the range of 20 wt. % to 65 wt. % with respect to the total weight of the woodworking adhesive composition. The composition comprises at least one adhesion promoter in an amount in the range of 0.1 wt. % to 5 wt. % woodworking adhesive composition. Additionally, the composition comprises one or more additives. In an aspect of the present invention, a laminated board is disclosed. The laminated board comprises a laminate selected from a group consisting of paper laminate, acrylic laminate, PVC laminate, charcoal sheet, PVC louver, asbestos sheet, veneer sheet, aluminum composite panel, and corean sheet. The laminated board comprises a board selected from a group consisting of plywood, blockboard, particle board, high density high moisture resistance board (HDHMR), medium density fiber board (MDF), high density fiber board (HDF), wood-plastic composite board (WPC), PVC foamboard, fiber-cement board and natural fiber polymer composite board. Further, the spreadable hybrid woodworking adhesive composition is imposed between the laminate and the board. DETAILED DESCRIPTION OF THE INVENTION Reference throughout the specification to “various embodiments,” “some embodiments,” “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, appearances of the phrases “in various embodiments,” “in some embodiments,” “in one embodiment,” or “in an embodiment” in places throughout the 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. The words “comprising”, “having”, “containing”, and “including”, and other forms thereof are intended to be equivalent in meaning and be open-ended in that an item or items following any one of these words is not meant to be exhaustive listing of such item or items or meant to be limited to only the listed item or items. It must also be noted that the singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. Although any methods similar or equivalent to those described herein may be used in the practice or testing of embodiments of the present disclosure, the exemplary methods are described. The disclosed embodiments are merely exemplary of the disclosure, which may be embodied in various forms. Various modifications to the embodiment may be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. However, a skilled person in the art can readily recognize that the present disclosure is not intended to be limited to the embodiments illustrated but is to be accorded the widest scope consistent with the principles and features described herein. A detailed description of the invention will be described hereinafter. In the context of the present invention, the term “silylated polymer” refers to silane modified or silyl terminated polymer. The terms “modified silyl polymer”, “MS polymer”, and “silyl modified polyether” essentially mean the same thing and can be used interchangeably. The present disclosure relates to a spreadable wood working adhesive composition. This adhesive formulation is developed to overcome the limitations of conventional adhesives, such as polyvinyl acetate (PVAc) and rubber-based adhesives, which often exhibit issues like spreadability issues, poor water and heat resistance, warping, and prolonged curing times. The composition ensures enhanced adhesion, improved spreadability, and ease of application, making it suitable for use in furniture manufacturing, plywood bonding, and other woodworking processes. Additionally, the adhesive offers high initial tack, reducing the need for prolonged clamping or additional support materials like masking tape. The present disclosure relates to a spreadable hybrid woodworking adhesive composition comprising at least one silylated polymer, at least one plasticizer, at least one pigment particle, an antioxidant, at least one filler, and one or more additives. In one aspect, there is provided a spreadable hybrid woodworking adhesive composition comprising at least one silylated polymer in an amount in the range of 10 wt. % to 60 wt. % based on the total weight of the adhesive composition; at least one plasticizer in an amount in the range of 5 wt. % to 30 wt. % based on the total weight of the adhesive composition; at least one filler in an amount in the range of 20 wt. % to 65 wt. % based on the total weight of the adhesive composition; at least one adhesion promoter in an amount in the range of 0.1 wt. % to 5 wt. % based on the total weight of the formulation, and one or more additives. The hybrid woodworking adhesive composition of the present invention enables strong bonds across various substrates, including wood, metal, and composites, along with superior water and heat resistance, preventing issues like delamination and weakening over time. Additionally, the woodworking adhesive composition of the present invention imparts improved spreadability and ease of application, ensuring uniform coverage and strong initial tack without the need for additional fixation tools. In one embodiment, the silylated polymer is at least one selected from a group consisting of silylated polyether silylated polyurethane, and silyl terminated polyurethane. In one embodiment, the silylated polymer is at least one selected from a group consisting of acrylic modified silylated polyurethane (STPE), vinyl modified silylated polymer, epoxy modified silylated polymer, and polyester modified silylated polymer. In a preferred embodiment, the silylated polymer is selected from a group consisting of RISUN 668T, SAX 400, MS Polymer™, SPUR+ Prepolymers, Geniosil®, STP-E Polymers, and Kane Ace™ MX. In one embodiment, the silylated polymer is present in an amount in the range of 10 wt. % to 60 wt. % based on the total weight of the adhesive composition. Preferably, the silylated polymer is present in an amount in the range of 10 wt. % to 50 wt. % based on the total weight of the adhesive composition. More preferably, the silylated polymer is present in an amount in the range of 12 wt. % to 40 wt. % based on the total weight of the adhesive composition. In an embodiment, the composition comprises of at least one plasticizer. Plasticizers enhance flexibility, workability, and spreadability of the adhesive and helps to reduce viscosity, allowing for smooth application and uniform coverage while preventing brittleness in the cured adhesive. They also improve the adhesive's resistance to cracking, ensuring long-term durability and maintaining strong bonding performance under varying environmental conditions. In one embodiment, the at least one plasticizer is selected from a group consisting of phthalates, phosphates, polyesters, and glycols. In a preferred embodiment, the at least one plasticizer is selected from a group consisting of 1,2- cyclohexanedicarboxylic acid diisononyl (DINP) ester, diisononyl (DINP) ester, diisononyl phthalate (vinyl), polypropylene glycol, and C15-C20 dearomatized aliphatic fluid. In one embodiment, the at least one plasticizer is present in an amount in the range of 5 wt. % to 30. wt % based on the total weight of the adhesive composition. In a preferred embodiment, the at least one plasticizer is present in an amount in the range of 5wt. % to 25 wt. % based on the total weight of the adhesive composition. In an embodiment, the composition comprises of at least one filler. Fillers improve dimensional stability, reduce shrinkage upon curing, and modify properties such as flexibility, hardness, and adhesion to various substrates. The inclusion of fillers also helps in controlling rheology, preventing sagging during application, and optimizing the formulation for specific end-use requirements. In an embodiment, the at least one filler is selected from a group consisting of calcium carbonate, silica, expandable graphite, alkali metal silicates, talc, vermiculite, and gas filled microspheres. In a preferred embodiment, the at least one filler is calcium carbonate. In a preferred embodiment, the calcium carbonate is a ground calcium carbonate, or a precipitated calcium carbonate or a combination thereof. In another embodiment, the at least one filler in an amount in the range of 20 wt. % to 65 wt. % based on the total weight of the adhesive composition. In a preferred embodiment, the at least one filler in an amount in the range of 25 wt. % to 55 wt. % based on the total weight of the adhesive composition. In yet another embodiment, the at least one filler particle has a particle size in the range of 30 nm to 15 µm. In a preferred embodiment, the at least one filler particle has a particle size in the range of 25 nm to 10 µm. In an embodiment, the composition comprises of at least one adhesion promoter selected from a group consisting of aminopropyl trimethoxysilanes, propyltrimethoxysilanes, polyfunctional epoxy silanes, Oligomeric diamino-functional siloxane. In an embodiment, the composition comprises of at least one adhesion promoter selected from a group consisting of N-2-Aminoethyl-3-aminopropyl trimethoxysilane (DAMO), 3- Glycidoxypropyltrimethoxysilane (Silquest A-187), oligomeric diamino-functional siloxane (Dynasylan® 1146), 3-aminopropyltrimethoxysilane (AMMO), and polyfunctional epoxy silane (CoatOSil™ MP 200). In a related embodiment, the at least one adhesion promoter in an amount in the range of 0.1 wt. % to 5 wt. %. In a preferred embodiment, the at least one adhesion promoter in an amount in the range of 0.1 wt. % to 3 wt. % based on the total weight of the adhesive composition. In an embodiment, the composition comprises of one or more additives, to enhance processing, performance, and durability of the adhesive. The selection and concentration of additives are optimized to ensure the adhesive maintains its desired properties, stability, and ease of application under various environmental conditions. In an embodiment, the one or more additives are selected from a group consisting of catalyst, water scavengers, anticoagulant, reinforcing fibres, adhesion promoters, fragrances, ultraviolet stabilizers, fungicides, heat stabilizers, fire retardants, and hindered amine light stabilizers (HALS) or a combination thereof. In an embodiment, the composition comprises of at least one pigment particle, to provide colour, opacity, and enhanced visual appeal while also offering functional benefits such as UV resistance and improved durability. Pigments help in achieving uniform coloration, masking surface imperfections, and enhancing product identification. Depending on the application, the pigment is organic or inorganic, with examples including titanium dioxide for whiteness and opacity, carbon black for deep coloration, and iron oxides for earthy tones. In a related embodiment, the at least one pigment particle selected from a group consisting of titanium dioxide, carbon black, an organic pigment, and an inorganic pigment. In a preferred embodiment, the at least one pigment particle is titanium dioxide. In another related embodiment, the at least one pigment particle is present in an amount in the range of 0.5 wt. % to 3.5 wt. % based on the total weight of the adhesive composition. In a preferred embodiment, the at least one pigment particle is present in an amount in the range of 1 wt. % to 3 wt. % based on the total weight of the adhesive composition. In an embodiment, the composition comprises an antioxidant to enhance the stability and longevity of the adhesive by preventing oxidative degradation. Antioxidants help protect the polymer matrix from thermal, UV, and environmental stress, which leads to brittleness, discoloration, or loss of adhesion over time. In a embodiment, the antioxidant is selected from a group consisting of butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), Irganox 1010 (pentaerythritol tetrakis(3,5-di-tert-butyl- 4-hydroxyhydrocinnamate)), Irganox 1076 (octadecyl 3-(3,5-di-tert-butyl-4- hydroxyphenyl)propionate), and Irgafos 168 (tris(2,4-di-tert-butylphenyl) phosphite). In another related embodiment, the antioxidant is present in an amount in the range of 0.05 wt. % to 0.5 wt. %based on the total weight of the adhesive composition. In a preferred embodiment, the antioxidant is present in an amount in the range of 0.1 wt. % to 0.3 wt. % based on the total weight of the adhesive composition. In an embodiment, the composition includes at least one moisture scavenger, which plays a critical role in enhancing the stability and performance of the formulation. A moisture scavenger is designed to absorb and remove any residual moisture present within the composition, thereby preventing undesirable reactions such as hydrolysis or degradation of sensitive components. This contributes to improving the shelf-life, consistency, and overall effectiveness of the product, particularly in applications where moisture control is crucial for maintaining the desired properties, such as adhesion, curing, and mechanical strength. In a related embodiment, the at least one moisture scavenger is selected from a group consisting of alkyl trimethoxysilanes. In a related embodiment, the at least one moisture scavenger is selected from a group consisting of vinyltrimethoxysilane (VTMO), propyltrimethoxysilane (PTMO), and propyltriethoxysilane (PTEO). In an embodiment, the at least one moisture scavenger in an amount in the range of 0.5 wt. % to 5 wt. % based on the total weight of the adhesive composition. In a preferred embodiment, the at least one moisture scavenger in an amount in the range of 1 wt. % to 4.5 wt. % based on the total weight of the adhesive composition. In an embodiment, the composition comprises of a catalyst. The catalyst is selected from a group consisting of dibutyltin dilaurate, dibutyltin dioctoate, dibutyltin diacetate, dioctyltin dilaurate, organometallic compounds, amine compounds and aminosilanes and N-β-(aminoethyl)-γ- aminopropyltrimethoxysilane, dialkylhydroxylamines, guanidyl containing silanes, or combination thereof. In an embodiment, viscosity of the composition is in the range of 40000 to 90000 centipoise (cps). In a preferred embodiment, the viscosity of the composition is in the range of 42000 to 88000 centipoise (cps). In an embodiment, shore A hardness of the composition as per the ASTM C661 is in the range of 30 to 50. In a preferred embodiment, the shore A hardness of the composition is in the range of 35 to 45. In an embodiment, tensile strength of the composition as per the ASTM D412 is in the range of 0.1 to 3 Mpa. In a preferred embodiment, the tensile strength of the composition is in the range of 0.5 to 2.5 Mpa. In an embodiment, lap shear strength of paper laminate plywood as per the ASTM D412 is in the range of 1 to 20 Kg / cm2. In a preferred embodiment, the lap shear strength of paper laminate plywood is in the range of 5 to 15 Kg / cm2. In another embodiment, lap shear strength of acrylic laminate plywood as per the ASTM D412 is in the range of 1 to 20 Kg / cm2. In a preferred embodiment, the lap shear strength of acrylic laminate plywood is in the range of 5 to 15 Kg / cm2. In an embodiment, skin formation time of the composition as per the ASTM D679 is in the range of 10 to 25 Min. In a preferred embodiment, the skin formation time of the composition is in the range of 12 to 22 Min. In an embodiment, density of the composition as per ASTM D1475-13 is in the range of 0.1 to 3 gm / cc. In a preferred embodiment, the density of the composition is in the range of 0.5 to 2.5 gm / cc. In an embodiment, elongation at break (%) of an adhesive film of the composition as per the ASTM D412 is in the range of 150 to 420. In a preferred embodiment, the elongation at break (%) of the composition is in the range of 157 to 416. In an embodiment, a laminated board is disclosed, that comprises multiple layers of materials bonded together to enhance structural integrity, durability, and functional performance. Typically, the board includes a core substrate such as wood, plastic, or composite laminated with one or more surface layers made from films, resins, or decorative materials. These surface layers provide specific properties such as moisture resistance, UV protection, chemical stability, or improved aesthetics. The lamination process involves the application of heat, pressure, or adhesives to achieve a strong and uniform bond between the layers. This type of laminated board can be used in various applications, including construction, furniture, packaging, and electronics, where enhanced mechanical strength and environmental resistance are desired. In a related embodiment, the laminate board is selected from a group consisting of paper laminate, acrylic laminate, PVC laminate, charcoal sheet, PVC louver, asbestos sheet, veneer sheet, aluminum composite panel, corean sheet. These laminates offer a range of functional and aesthetic properties suitable for different construction and design needs. In another related embodiment, the laminate board is selected from a from a group consisting of plywood, blockboard, particle board, high density high moisture resistance board (HDHMR), medium density fiber board (MDF), high density fiber board (HDF), wood-plastic composite board (WPC), polyvinyl chloride (PVC) foamboard, fiber-cement board and natural fiber polymer composite board. In yet another related embodiment, the spreadable hybrid woodworking adhesive composition is imposed between the laminate and the board. This adhesive serves as a crucial intermediary layer, promoting adhesion by effectively anchoring the laminate to the board’s surface while accommodating differences in material properties such as flexibility, porosity, and thermal expansion. The hybrid nature of the adhesive allows it to combine the benefits of different chemistries such as high bonding strength, moisture resistance, and workability making it suitable for various laminate types and board materials used in woodworking applications. In an embodiment, a method for preparing a spreadable hybrid woodworking adhesive composition is disclosed. The process involves mixing a silane-modified polymer, at least one plasticizer, at least one pigment particle, an antioxidant, and at least one filler in a double planetary power mixer at high speed to achieve uniform dispersion of the filler particles. The mixture is stirred at a temperature of 100 to 120 °C under full vacuum (less than -0.05 to -0.15 MPa) for 1 to 5 hours to reduce the moisture content below 800 to 1200 ppm. Once the desired moisture level is achieved, the material is cooled to 20 to 60 °C, followed by the addition of water scavenger, adhesion promoter, and catalyst into the mixer. The mixing process is continued for an additional 30 to 40 minutes under vacuum conditions to ensure homogeneous blending. The final composition results in a spreadable hybrid woodworking composition with improved bonding performance, moisture resistance, and ease of application. The following examples of the various embodiments reveal a deeper understanding of the various properties of the spreadable hybrid woodworking adhesive composition. Examples: Name of Raw Materials Description RISUN 668T Silyl terminated Polyether SAX 400 Silyl terminated Polyether Wingtack® 10 Molten Hydrocarbon base tackifier Kaneka MA 490 Acrylic modified STPE Kaneka MA 451 Acrylic modified STPE Diisononyl phthalate (DINP) (Vinyl)) Plasticizer Songnox 1076 Antioxidant Tio2 R 902 Rutile TiO2 pigment Omyacarb 1 T IP Ground calcium carbonate Silica 1240 Quartz Silica HDK H 18 Fumed silica TS 720 Fumed silica Fine Cal Precipitated calcium carbonate vinyltrimethoxysilane (VTMO) Moisture scavenger N-2-Aminoethyl-3-aminopropyl Adhesion promoter trimethoxysilane (DAMO SISIB) 3-Glycidoxypropyltrimethoxysilane Adhesion promoter (Silquest A 187) oligomeric diamino-functional Adhesion promoter siloxane (Dynasilane 1146) Dibutyltin dilaurate (DBTDL) Catalyst Neostan S1 Catalyst General procedure for the synthesis of Spreadable hybrid woodworking adhesive composition: A silylated polymer, plasticizer, pigments, antioxidant and fillers were mixed in a double planetary power mixer under continuous stirring at 105 °C under vacuum (less than -0.09 MPa) for 3 hours to obtain a first mixture with a moisture level of below 1000 ppm. The first mixture was cooled to 40 °C and was mixed with water scavenger, adhesion promoter and catalyst under stirring for 30 minutes under vacuum (less than -0.09 MPa) to obtain the spreadable hybrid woodworking adhesive composition. The formulations so prepared are summarised in table 1 given below. The subsequent Table 2 represents the Comparison of properties of compositions prepared in example 1 to 8. Table 1 Name of Description Ex.1 Ex.2 Ex.3 Com Com Ex.6 Ex.7 Com Raw p. p. p. Materials Ex.4 Ex.5 Ex.8 RISUN Silyl 15 - - 8 55 - - - 668T terminated Polyether SAX 400 Silyl - 15 20 - - - - - terminated Polyether Wingtack® Hydrocarbon - - - 3.6 - - - - 10 Molten base tackifier Kaneka MA Acrylic - - - - - 34.5 - - 490 modified STPE Kaneka MA Acrylic - - - - - - 34.5 55 451 modified STPE DINP(Vinyl Plasticizer 21.5 21.5 18 22.8 5 12.3 12.3 7 ) Songnox Antioxidant 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 1076 Tio2 R 902 TiO2 pigment - - - - 2 - - - Rutile Omyacarb 1 Ground 50 50 30 50.6 25 39 39 23 T IP calcium carbonate Silica 1240 Quartz Silica - - 27 - - - - - HDK H 18 Fumed silica - - - - 3 - - - TS 720 Fumed silica 2.6 2.6 2 2 - 0.5 0.5 1.3 Fine Cal Precipitated 8 8 10 7 10 10 10 calcium carbonate VTMO Moisture 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 scavenger DAMO Adhesion 1 1 1 1 1 2 2 2 SISIB promoter DBTDL Catalyst 0.2 0.2 0.3 0.3 0.3 - - - Neostan S1 Catalyst - - - - - 0.3 0.3 0.3 Table 2: Comparison of properties of compositions prepared in example 1 to 8 Properties Ex.1 Ex.2 Ex.3 Comp. Comp. Ex.6 Ex.7 Comp. Example Example Example 4 5 8 Appearance Low Low Low Low High Low Low High viscous viscous viscous viscous viscous viscous viscous Viscous paste paste paste paste paste paste paste paste Skin time 16 to 15 to 21 to 16 to 17 15 to 16 15 to 14 to 13 to 15 (Min) 17 20 22 16 15 Viscosity at 48500 52258 43160 40000 71500 53500 43724 83780 25 °C (cPs) Density at 1.42 1.43 1.48 1.42 1.38 1.35 1.37 1.35 25 °C (gm / cc) Paper 11.5 9.1 14.6 7.4 14.3 8.2 7.9 16.5 laminate - Plywood (Kg / cm2) Lap Shear strength Acrylic 7.3 5.9 7.8 4.2 8.6 9.5 8.4 9.2 laminate - Plywood (Kg / cm2) Lap Shear strength Tensile 1.55 1.6 1.58 1.25 1.67 1.43 1.3 1.8 Strength (Mpa) Elongation 416 370 246 292 284 213 197 175 at break (%) Hardness 38 42 42 36 39 38 37 44 (Shore A) Chisel test Passed Passed Passed Passed Passed Passed Passed Passed Water Passed Passed Passed Passed Passed Passed Passed Passed resistance test

[0002] From the data summarised in table 2, It is apparent that the formulation so prepared exhibits synergistic properties, and variations beyond the preferred formulation do not provide the same desirable results. The spreadable hybrid woodworking adhesive composition prepared as per the presently disclosed invention and examples 1, 2, 3, 6, and 7 of Table 2 showed optimum viscosity and good spreadability. The presently claimed composition also has high tensile strength and desired elongation at break values. The composition also pass Chisel Test and the water resistance test. On the contrary, the compositions as discussed in comparative examples 4, 5 and 8 has shown inferior properties such as comparative example 4 showed poor adhesive strength, and comparative example 5, and 8 showed very high viscosity and low spreadability as compared to the composition of the presently claimed invention. In summary, the presently claimed spreadable woodworking adhesive composition has the following advantageous functionalities over the conventional art: • The woodworking adhesive of the present invention demonstrates easy spreadability. • The woodworking adhesive of the present invention demonstrates high water resistance. • The woodworking adhesive of the present invention demonstrates high heat resistance. • Lower or no warping issue with plywood for laminate to plywood binding with woodworking adhesive composition of the present invention. • No bubble formation after applying the woodworking adhesive composition of the present invention. • No delamination after applying the woodworking adhesive composition of the present invention. • The woodworking adhesive of the present invention demonstrates strong bonding on plywood, PVC board, MDF board, furniture laminates, etc. The foregoing description shall be interpreted as illustrative and not in any limiting sense. A person of ordinary skill in the art would understand that certain modifications would be encompassed within the scope of this disclosure. The embodiments, examples and alternatives of the preceding paragraphs or the description, including any of their various aspects or respective individual features, are taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments unless such features are incompatible.

Claims

WE CLAIM:

1. A spreadable hybrid woodworking adhesive composition, comprising: at least one silylated polymer in an amount in the range of 10 wt. % to 60 wt. % based on the total weight of the adhesive composition; at least one plasticizer in an amount in the range of 5 wt.% to 30 wt. % based on the total weight of the adhesive composition; at least one filler in an amount in the range of 20 wt. % to 65 wt. % based on the total weight of the adhesive composition; at least one adhesion promoter in an amount in the range of 0.1 wt. % to 5 wt. % based on the total weight of the formulation, and one or more additives.

2. The woodworking adhesive composition as claimed in claim 1, wherein the at least one silylated polymer is selected from a group consisting of silane modified polyether and silane modified polyurethane.

3. The woodworking adhesive composition as claimed in claim 1, wherein the at least one silylated polymer is acryl modified silylated polymer, vinyl modified silylated polymer, epoxy modified silylated polymer, and polyester modified silylated polymer.

4. The woodworking adhesive composition as claimed in claim 1, wherein the at least one plasticizer is selected from a group consisting of phthalates, phosphates, polyesters, and glycols.

5. The woodworking adhesive composition as claimed in claim 1, wherein the at least one filler is selected from a group consisting of calcium carbonate, silica, expandable graphite, alkali metal silicates, talc, vermiculite, and gas filled microspheres.

6. The woodworking adhesive composition as claimed in claim 1, wherein the at least one filler has particle size in the range of 30 nm to 15 µm.

7. The woodworking adhesive composition as claimed in claim 1, wherein the at least one adhesion promoter is selected from a group consisting of n-2-aminoethyl-3-aminopropyltrimethoxysilane, 3- glycidoxypropyltrimethoxysilane, oligomeric diamino-functional siloxane, 3-aminopropyltrimethoxysilane, and polyfunctional epoxy silane.

8. The woodworking adhesive composition as claimed in claim 1, comprises at least one catalyst in an amount in the range of 0.1 wt. % to 5 wt. % based on the total weight of the adhesive composition.

9. The woodworking adhesive composition as claimed in claim 1, comprises at least one antioxidant in an amount in the range of 0.05 wt. % to 0.5 wt. % based on the total weight of the adhesive composition.

10. The woodworking adhesive as claimed in claim 1, comprises at least one moisture scavenger in an amount in the range of 0.5 wt. % to 5 wt. % based on the total weight of the adhesive composition.

11. The woodworking adhesive composition as claimed in claim 1, wherein the at least one catalyst is selected from a group consisting of dibutyltin dilaurate, dibutyltin dioctoate, dibutyltin diacetate, dioctyltin dilaurate, organometallic compounds, amine compounds and aminosilanes and N-β-(aminoethyl)-γ- aminopropyltrimethoxysilane, dialkylhydroxylamines, guanidyl containing silanes, or combination thereof.

12. The woodworking adhesive composition as claimed in claim 1, wherein the one or more additives comprises at least one selected from a group consisting of anticoagulant, reinforcing fibres, fragrances, ultraviolet stabilizers, fungicides, heat stabilizers, fire retardants, and hindered amine light stabilizers (HALS) or a combination.

13. The woodworking adhesive composition as claimed in claim 1, wherein the viscosity of the adhesive composition is in the range of 40000 to 90000 centipoise (cps).

14. The woodworking adhesive composition as claimed in claim 1, wherein shore A hardness of the adhesive composition is in the range of 30 to 50.

15. The woodworking adhesive composition as claimed in claim 1, wherein the tensile strength of the adhesive composition is in the range of 0.1 to 3 Mpa.

16. A laminated board, comprising:a laminate selected from a group consisting of paper laminate, acrylic laminate, PVC laminate, charcoal sheet, PVC louver, asbestos sheet, veneer sheet, aluminum composite panel, corean sheet; a board selected from a group consisting of plywood, blockboard, particle board, high density high moisture resistance board (HDHMR), medium density fiber board (MDF), high density fiber board (HDF), wood-plastic composite board (WPC), polyvinyl chloride (PVC) foamboard, fiber-cement board and natural fiber polymer composite board; and the spreadable hybrid woodworking adhesive composition as claimed in claims 1 to 15, imposed between the laminate and the board.