Claims:We Claim:

1. Polyvinyl acetate based polymeric emulsion/adhesive comprising polymeric emulsion of cross linker free copolymer particle of monomers including vinyl acetate monomer, di-functional monomer, silane functional monomer, Isobornyl methacrylate monomer together with hydrolyzed polyvinyl alcohol, said copolymer particle having Isobornyl methacrylate monomer based moiety protruding outside of or on the surface of said polymer particle enabling wet adhesive strength upto 1.5 N/m2.

2. The polyvinyl acetate based polymeric emulsion/adhesive as claimed in claim 1 wherein said polymeric emulsion of cross linker free copolymer particle of monomers includes by wt. of the emulsion 33-50 wt% vinyl acetate monomer, 0.01-0.024 wt.% di-functional monomer, 0.25-0.75 wt.% Isobornyl methacrylate monomer, 0.08-0.12 wt.% silane functional monomer together with polyvinyl alcohol that is fully hydrolyzed in the levels of 2.8-4.2 wt.% said hydrolyzed polyvinyl alcohol having a degree of hydrolysis ranging from 93 mol% to 99 mol% and viscosity between 22 mPa·s to 32 mPa·s at 20-25 ?C.

3. The polyvinyl acetate based polymeric emulsion/adhesive as claimed in claims 1 or 2 wherein said polymeric emulsion of external cross linker free copolymer particle comprises metal catalyst free emulsion copolymerized copolymer particle free of external crosslinkers including aluminum chloride, aluminum nitrate, zirconium nitrate, zirconium chloride, glyoxal, glutaraldehyde.

4. The polyvinyl acetate based polymeric emulsion/adhesive as claimed in claims 1-3 that is fortified with the attributes of said wet adhesive strength as per D3 criteria of EN 204 testing even in being free of any metal/ other catalysts and external cross linkers; and is storage stable passing accelerated stability test at 55?C for 30 days.

5. The polyvinyl acetate based polymeric emulsion/adhesive as claimed in claims 1-4 wherein said di-functional monomer includes diallyl phthalate, ethylene glycol dimethacrylate, diacetone-acrylamide, acetoacetoxyethyl methacrylate; and silane functional monomers includes vinyl trimethoxy silane, vinyl triethoxy silane, 3-methacryloxpropyl trimethoxysilane, 3- methacryloxypropyl triethoxysilane.

6. A process for the synthesis of polyvinyl acetate based polymeric emulsion/adhesive as claimed in claim 1-5 comprising providing monomers including vinyl acetate monomer, di-functional monomer, silane functional monomer, Isobornyl methacrylate monomer together with hydrolyzed polyvinyl alcohol, as monomer charge free of any external cross linkers and emulsion polymerizing the monomer charge free of any metal catalysts with delayed incorporation of Isobornyl methacrylate as monomer during emulsion polymerizing the monomer charge such as to obtain polymer particles of polyvinyl acetate based copolymer having said Isobornyl methacrylate monomer based moiety protruding outside of or on the surface of the copolymer particle.

7. The process for the synthesis of polyvinyl acetate based polymeric emulsion/adhesive as claimed in claim 6 wherein
said delayed addition involves power feed technique in emulsion polymerization process, with addition of Isobornyl methacrylate into monomer mix happening after completion of 240 minutes addition of monomer charge into the reactor for emulsion polymerization and wherein rest 60 minutes of monomer addition takes place by involving isobornyl methacrylate monomer for 100 gms emulsion batch size, thereby favouring Isobornyl methacrylate monomer based moiety to be protruding outside the polymer particle with the particle surface having more of Isobornyl methacrylate, thereby providing for improved adhesive strength of such polymer emulsion/adhesive free of external crosslinkers free of metal catalysts.

8. The process for the synthesis of polyvinyl acetate based polymeric emulsion/adhesive as claimed in claims 6 or 7 wherein said process comprises the steps of

Providing in a glass reactor a reactor charge of de-mineralised water, polyvinyl alcohol (PVOH) that is heated to 85-90°C for 1-1.5 hours under continuous stirring at 150-160 RPM for dissolution;
Providing in a separate vessel in sequence monomers including vinyl acetate, di-functional monomer, silane functional monomer and mixing them;
Preparing HPO (Hydrogen peroxide), and tartaric acid solution, sodium acetate solutions in separate vessels for addition in seeding stage;
Post dissolution of PVOH the reactor was cooled to 65°C and seeding was carried out by sequentially adding sodium acetate, tartaric acid, HPO solution together with part of vinyl acetate monomer, in dissolved PVOH with simultaneous addition of initiator for generation of seed polymers;
Post generation of seed polymers in the reactor, monomer mix addition including monomers vinyl acetate, di-functional monomer, silane functional monomers was continued over a period of 5 hours with separate and simultaneous addition of initiator, tartaric acid solution and HPO solution into the reactor at uniform rate by maintaining temperature throughout at 70°C, which involves an intermediate step of a further monomer addition; said intermediate step being addition of isobornyl methacrylate monomer in the reactor after 240 minutes or 4 hours of monomer mix addition that was continued for another 1 hour of the total 5 hours of monomer mix addition in the reactor involving simultaneously added HPO solution and tartaric acid solution;
Digesting the reactor charge at temperature of 70°C for 1 hour followed by cooling the reactor to 30°C and adding additives and mixing again for 5 minutes and filtering to obtain said polymeric emulsion/adhesive.

9. The process for the synthesis of polyvinyl acetate based polymeric emulsion/adhesive as claimed in claims 6 or 7 wherein said initiator include ammonium persulphate-Sodium metabisulphite, tertiary butyl hydroperoxide-sodium formaldehyde sulphoxylate, hydrogen peroxide-tartaric acid, potassium persulphate.

Dated this the 25th day of March, 2022 Anjan Sen
Of Anjan Sen and Associates
(Applicants Agent)
IN/PA-199

, Description:FIELD OF THE INVENTION

The present invention provides for improved polyvinyl acetate based adhesive with improved wet adhesive strength free of external crosslinkers and a process for obtaining the same based on emulsion polymerization free of any metal catalyst and said external crosslinkers.

BAKGROUND ART

Polyvinyl acetate based adhesives being highly water sensitive poses the risk of performing poor adhesion under wet conditions. Prior art indicates the polymer to be crosslinked using external crosslinkers viz; metal catalyst etc.

Reference is drawn to the following prior patents:

CN107383265 teaches a kind of water-fast grades to meet EN204 D3 standard one-component carpenter adhesive preparation process; this method is using acetoacetylate modified polyvinylalcohol as protecting colloid, including defoaming agent, electrolyte, redox initiation system, emulsifier, vinylacetate, function monomer, preservative and water etc.

US3284280 teaches an aqueous adhesive composition comprising a mixture of an emulsion of a water-insoluble partially hydrolyzed polyvinyl acetate together with trimethylol phenol; wherein said partially hydrolyzed polyvinyl acetate contains from about 7 to about 21% of hydroxyl groups, as based on the original number of acetate groups in the polymer.

US 7,585,915 B2 teaches aqueous dispersion adhesive based on a polymer dispersion comprising at least one emulsion polymer containing crosslinkable N-methylol groups, derived through the incorporation of up to 2.0% by weight, based on the total monomer amount, of N-methylol-containing co-monomers into the emulsion polymer, at least one protective colloid, and at least one crosslinking agent containing N-methylol groups fully or partly etherified with one or more alkanols and/or other hydroxyl groups fully or partly etherified with one or more alkanols, selected from the group consisting of hydroxymethylated cyclic ethyleneureas, hydroxymethylated cyclic propyleneureas, hydroxymethylated bicyclic glyoxal diureas, hydroxymethylated bicyclic malonaldehyde diureas, and combinations thereof.

US 2010/0179272A1 is directed to compositions containing an aqueous dispersion of selected polymers and selected polyaldehydes as crosslinking agents are described enabling adhesives having very high resistance to boiling water can be produced from these formulations.

US5545684 directs to aqueous emulsion adhesives having a pH from 2 to 6 which comprise homo- or copolymeric polyvinyl esters, polymeric protective colloids, water-soluble compounds which can be complexed with the polymeric protective colloids, and at least partially masked polyaldehydes having at least 3 carbon atoms from which aldehyde groups can be released in a controlled manner in acidic media are suitable for bonding porous and semiporous substrates.

WO2013057214 A1 discloses a dispersion of a formaldehyde free vinyl homopolymer or copolymer with a high molecular weight, including at least one modified polyvinyl alcohol with a high degree of hydrolysis (>95%) suitable to formulate non-structural thermoplastic wood adhesives with high water resistance according to EN-204/205, heat resistance according to standard EN-14257 exceeding 7 N/mm2, and shelf life exceeding 3 months.

CN104403608 teaches water-tolerant polyvinyl acetate wood adhesive and a preparation method thereof. The water-tolerant polyvinyl acetate wood adhesive comprises the following compositions in parts by mass: 2-4 parts of polyvinyl alcohol, 45-49 parts of vinyl acetate, 0.08-0.2 part of an oxidizing agent in a redox initiator, 0.08-0.18 part of a reducing agent in a redox initiator, 0.09-0.15 part of a buffering agent, and 50 parts of water. The polyvinyl acetate adhesive prepared by using the method is prepared by employing a redox initiation system, the preparation process can be efficiently performed at a lower temperature, and the preparation technology is simple. Compared with common 1788 and 1799 protective adhesives, the prepared polyvinyl acetate wood adhesive has the water resistance reaching Europe D3 standard and good water resistance.

JP2015189811 describes involving vinyl alcohol containing acetoacetylated polyvinyl alcohol as a protective colloid, vinyl acetate monomer emulsion polymerized, or vinyl acetate resin emulsion copolymerized vinyl acetate monomer and acetoacetyl monomer, compounded with metal compound A water-based adhesive characterized by being formed.

Reference is also invited to CN 109337621B that teaches low-deformation, moisture-free water-based adhesive comprises (in parts by mass) deionized water 30-45, protective colloidal polyvinyl alc. 3-10, nonionic emulsifier 0.5-2, buffer 0.1-0.5, persulfate initiator 0.5-0.8, vinyl acetate 20-35, acrylate monomer 10-25, crosslinker 0.5-1, methoxypolyethylene glycol acrylate 510, moisturizer 3-10, defoamer 0.1-0.3, wetting agent 0.1-0.3, preservative 0.1-0.3 and plasticizer 5-10. Principal claim 1 therein scopes low deformation exempts from to take out wet water base mount book glue which characterized in that: the feed is prepared from the following raw materials in parts by weight: 30.0 to 45.0 portions of deionized water Protective colloid polyvinyl alcohol 3.0-10.0 parts 0.5 to 2.0 portions of non-ionic emulsifier 0.1 to 0.5 portion of buffering agent 0.5-0.8 part of persulfate initiator 20.0-35.0 parts of vinyl acetate Monomer 10.0-25.0 parts 0.5 to 1.0 portion of cross-linking agent 5.0-10.0 parts of methoxy polyethylene glycol acrylate
Humectant 3.0-10.0 parts 0.1 to 0.3 portion of defoaming agent 0.1 to 0.3 portion of etting agent 0.1 to 0.3 portion of preservative 5.0-10.0 parts of a plasticizer; the monomer is at least one of methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, n-octyl crylate, isooctyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, isooctyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, allyl glycidyl ether and isobornyl methacrylate.

US 2005/0215700 A1 teaches stable, heat resistant colloid stabilized water based bicomponent wood adhesive based on vinyl acetate and N-methylolacrylamide as a cross-linking agent and also including an aromatic and/or cyclo aliphatic monomer, such as 2-phenoxy ethyl acrylate and/or isobornyl methacrylate, and methyl methacrylate. The colloid system contains a high molecular weight partially hydrolyzed polyvinylalcohol and one or more intermediate hydrolyzed polyvinyl alcohols.

While a plethora of work has been done on polyvinyl acetate based adhesives to improve its wet adhesive strength as would be apparent from the state of the art reveled above, there still remains a need for its improvement to attain alternative polyvinyl acetate based adhesive with improved wet adhesive strength and stability that is free of any external cross-linkers and would be formed free of any metal catalysts causing less inventory management and hence attainable through a more facile process.

OBJECTS OF THE INVENTION

It is thus the primary object of the present invention to provide for polyvinyl acetate based adhesive with improved wet adhesive strength that is free of any external cross-linkers.

Another object of the present invention is to provide for a facile process for preparing polyvinyl acetate based adhesive with improved wet adhesive strength that is free of any external cross-linkers and metal catalysts in its process of preparation that is based on the involvement of hydrophobic monomer Isobornyl methacrylate in the process by employing power feed technique.

Yet another object of the present invention is to provide for said polyvinyl acetate based adhesive that is stable and less water sensitive under wet conditions.

SUMMARY OF THE INVENTION

Thus according to the basic aspect of the present invention there is provided polyvinyl acetate based polymeric emulsion/adhesive comprising polymeric emulsion of cross linker free copolymer particle of monomers including vinyl acetate monomer, di-functional monomer, silane functional monomer, Isobornyl methacrylate monomer together with hydrolyzed polyvinyl alcohol, said copolymer particle having Isobornyl methacrylate monomer based moiety protruding outside of or on the surface of said polymer particle enabling wet adhesive strength upto 1.5 N/m2.

According to a preferred aspect of the present invention there is provided polyvinyl acetate based polymeric emulsion/adhesive wherein said polymeric emulsion of cross linker free copolymer particle of monomers includes by wt. of the emulsion 33-50 wt% vinyl acetate monomer, 0.01-0.024 wt.% di-functional monomer, 0.25-0.75 wt.% Isobornyl methacrylate monomer, 0.08-0.12 wt.% silane functional monomer together with polyvinyl alcohol that is fully hydrolyzed in the levels of 2.8-4.2 wt.% said hydrolyzed polyvinyl alcohol having a degree of hydrolysis ranging from 93 mol% to 99 mol% and viscosity between 22 mPa·s to 32 mPa·s at 20-25 ?C.

Preferably in said polymeric emulsion of external cross linker free copolymer particle comprises metal catalyst free emulsion copolymerized copolymer particle free of external crosslinkers including aluminum chloride, aluminum nitrate, zirconium nitrate, zirconium chloride, glyoxal, glutaraldehyde.

Advantageously said polyvinyl acetate based polymeric emulsion/adhesive is fortified with the attributes of said wet adhesive strength as per D3 criteria of EN 204 testing even in being free of any metal/ other catalysts and external cross linkers; and is storage stable passing accelerated stability test at 55?C for 30 days.

Preferably said di-functional monomer in the emulsion/ adhesive includes diallyl phthalate, ethylene glycol dimethacrylate, diacetone-acrylamide, acetoacetoxyethyl methacrylate; and silane functional monomers includes vinyl trimethoxy silane, vinyl triethoxy silane, 3-methacryloxpropyl trimethoxysilane, 3- methacryloxypropyl triethoxysilane.

According to another aspect of the present invention there is provided a process for the synthesis of polyvinyl acetate based polymeric emulsion/adhesive comprising providing monomers including vinyl acetate monomer, di-functional monomer, silane functional monomer, Isobornyl methacrylate monomer together with hydrolyzed polyvinyl alcohol, as monomer charge free of any external cross linkers and emulsion polymerizing the monomer charge free of any metal catalysts with delayed incorporation of Isobornyl methacrylate as monomer during emulsion polymerizing the monomer charge such as to obtain polymer particles of polyvinyl acetate based copolymer having said Isobornyl methacrylate monomer based moiety protruding outside of or on the surface of the copolymer particle.

Preferably in said process for the synthesis of polyvinyl acetate based polymeric emulsion/adhesive wherein
said delayed addition involves power feed technique in emulsion polymerization process, with addition of Isobornyl methacrylate into monomer mix happening after completion of 240 minutes addition of monomer charge into the reactor for emulsion polymerization and wherein rest 60 minutes of monomer addition takes place by involving isobornyl methacrylate monomer for 100 gms emulsion batch size, thereby favouring Isobornyl methacrylate monomer based moiety to be protruding outside the polymer particle with the particle surface having more of Isobornyl methacrylate, thereby providing for improved adhesive strength of such polymer emulsion/adhesive free of external crosslinkers free of metal catalysts.

More preferably, a process for the synthesis of polyvinyl acetate based polymeric emulsion/adhesive is provided wherein said process comprises the steps of

Providing in a glass reactor a reactor charge of de-mineralised water, polyvinyl alcohol (PVOH) that is heated to 85-90°C for 1-1.5 hours under continuous stirring at 150-160 RPM for dissolution;
Providing in a separate vessel in sequence monomers including vinyl acetate, di-functional monomer, silane functional monomer and mixing them;
Preparing HPO (Hydrogen peroxide), and tartaric acid solution, sodium acetate solutions in separate vessels for addition in seeding stage;
Post dissolution of PVOH the reactor was cooled to 65°C and seeding was carried out by sequentially adding sodium acetate, tartaric acid, HPO solution together with part of vinyl acetate monomer, in dissolved PVOH with simultaneous addition of initiator for generation of seed polymers;
Post generation of seed polymers in the reactor, monomer mix addition including monomers vinyl acetate, di-functional monomer, silane functional monomers was continued over a period of 5 hours with separate and simultaneous addition of initiator, tartaric acid solution and HPO solution into the reactor at uniform rate by maintaining temperature throughout at 70°C, which involves an intermediate step of a further monomer addition; said intermediate step being addition of isobornyl methacrylate monomer in the reactor after 240 minutes or 4 hours of monomer mix addition that was continued for another 1 hour of the total 5 hours of monomer mix addition in the reactor involving simultaneously added HPO solution and tartaric acid solution;
Digesting the reactor charge at temperature of 70°C for 1 hour followed by cooling the reactor to 30°C and adding additives and mixing again for 5 minutes and filtering to obtain said polymeric emulsion/adhesive.

According to another preferred aspect of the process for the synthesis of polyvinyl acetate based polymeric emulsion/adhesive said initiator include ammonium persulphate-Sodium metabisulphite, tertiary butyl hydroperoxide-sodium formaldehyde sulphoxylate, hydrogen peroxide-tartaric acid, potassium persulphate.

DETAILED DESCRIPTION OF THE INVENTION

As discussed hereinbefore, the present invention provides for improved polyvinyl acetate based adhesive with improved wet adhesive strength free of external crosslinkers and a process for obtaining the same based on emulsion polymerization.

According to one embodiment of the present invention during synthesis of emulsion polymer by emulsion polymerization towards preparation of the adhesive, addition of hydrophobic monomer Isobornyl methacrylate into monomer mix happens by employing power feed technique, especially after completion of 240 minutes addition of monomer mix into the reactor depending on the 100 gms total reactor charge while preparing said emulsion polymer by emulsion polymerization, with the rest 60 minutes of 300 minutes procedure, Isobornyl methacrylate monomer is added enabling the Isobornyl methacrylate moiety to be protrouding outside the polymer particle and the particle surface having more of Isobornyl methacrylate.
The present invention thus could build adhesive type polymer particles out of polyvinyl acetate emulsion polymer with improved wet adhesive strength free of external crosslinkers based on particular sequence of addition of hydrophobic monomer Isobornyl methacrylate during its synthesis that is important to derive the properties/ attributes of increasing wet adhesive strength of the system under consideration.

EXAMPLES and PROCESS description:

To the glass reactor add De-mineralised water, polyvinyl alcohol and heat it to 85-90°C for 1-1.5 hours under continuous stirring at 150-160 RPM.
To a separate vessel (PE/monomer vessel), add in sequence the ingredients, mentioned in monomer addition. Mix them well.
Prepare Hydrogen Peroxide – Tartaric acid solution in separate vessels as mentioned in seeding stage. Prepare sodium acetate solution in another vessel. After dissolution of PVOH, cool the reactor to 65°C and add ingredients in sequence as mentioned in seeding stage.
Start the monomer mixture addition over a period of 5 hours and maintain temperature throughout at 70°C. Prepare tartaric acid solution and add into the reactor Prepare HPO solution separately and feed it simultaneously in reactor at uniform rate over a period of 5 hours.
Add isobornyl methacrylate monomer in rest monomer mixture and mix well. Continue the addition (Isobornyl methacrylate addition stages are varying with examples).
After completion of monomer addition, add HPO solution and tartaric acid solution prepared separately in two different vessels as mentioned in digestion catalysts.
Maintain the temperature at 70°C for digestion for 1 hour
Cool the reactor to 30°c and add the ingredients mentioned in additives stage, mix it for 5 minutes and filter it with nylon cloth of 80 mesh size
Similar experiments were carried out for IBOMA (Isobornyl methacrylate) addition through monomer mixture at different stages.
TABLE NO: 1
R.M. Description Exp 01
IBOMA throughout Exp 02
IBOMA in seed only Exp 03
IBOMA After seed Exp 04 IBOMA After 1 hour Exp 05 IBOMA After 2 hours Exp 06 IBOMA After 3 hours Exp 07 IBOMA After 4 hours Exp 08 wihout IBOMA
Reactor charge-I (85 deg 1.5 hr)
Fully hydrolysed Poly vinyl alcohol 2.8-4.2 2.8-4.2 2.8-4.2 2.8-4.2 2.8-4.2 2.8-4.2 2.8-4.2 2.8-4.2
DM Water 33-50 33-50 33-50 33-50 33-50 33-50 33-50 33-50
Sodium acetate 0.1-0.15 0.1-0.15 0.1-0.15 0.1-0.15 0.1-0.15 0.1-0.15 0.1-0.15 0.1-0.15
DM Water 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
Seeding stage
10% Tartaric acid solution (dump) 0.6-1.0 0.6-1.0 0.6-1.0 0.6-1.0 0.6-1.0 0.6-1.0 0.6-1.0 0.6-1.0
5% HPO solution (dump) 0.4-0.6 0.4-0.6 0.4-0.6 0.4-0.6 0.4-0.6 0.4-0.6 0.4-0.6 0.4-0.6
Vinyl acetate (Feed in 10 minutes) 3.0-5.0 3.0-5.0 3.0-5.0 3.0-5.0 3.0-5.0 3.0-5.0 3.0-5.0 3.0-5.0
Addition stage of IBOMA Throughout mix for 5 hr Mix In seed only After seed mix in monomer After 1 hr mix in monomer After 2 hr mix in monomer After 3 hr in monomer mix After 4 hr in monomer mix N/A
ISO BORNYL METHACRYLATE 0.25-0.75 0.25-0.75 0.25-0.75 0.25-0.75 0.25-0.75 0.25-0.75 0.25-0.75 0.0
Initiator simultaneous addition for 5 hours
10% Tartaric acid solution (Dump) 0.13-0.2 0.13-0.2 0.13-0.2 0.13-0.2 0.13-0.2 0.13-0.2 0.13-0.2 0.13-0.2
1% HPO (Feed-II)-continuous feed 2.0-3.2 2.0-3.2 2.0-3.2 2.0-3.2 2.0-3.2 2.0-3.2 2.0-3.2 2.0-3.2
DMW 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00
Monomer addition for 5 hrs For 4 hrs For 4 hrs For 4 hrs For 4 hrs For 4 hrs For 4 hrs For 4 hrs
Vinyl acetate (Feed-I) 30-45 30-45 30-45 30-45 30-45 30-45 30-45 30-45
Di-functional monomer 0.01-0.024 0.01-0.024 0.01-0.024 0.01-0.024 0.01-0.024 0.01-0.024 0.01-0.024 0.01-0.024
Addition stage
Throughout mix for 5 hr After 4 hrs After 4 hrs After 4 hrs After 4 hrs After 4 hrs After 4 hrs After 4 hrs
Vinyl acetate 3.1-4.7 3.1-4.7 3.1-4.7 3.1-4.7 3.1-4.7 3.1-4.7 3.1-4.7 3.1-4.7
Silane functional monomer 0.08-0.12 0.08-0.12 0.08-0.12 0.08-0.12 0.08-0.12 0.08-0.12 0.08-0.12 0.08-0.12
Digestion catalyst
10% Tartaric acid solution 0.1-0.2 0.1-0.2 0.1-0.2 0.1-0.2 0.1-0.2 0.1-0.2 0.1-0.2 0.1-0.2
5% HPO solution 0.08-0.12 0.08-0.12 0.08-0.12 0.08-0.12 0.08-0.12 0.08-0.12 0.08-0.12 0.08-0.12
Additives
In-can preservative 0.15-0.25 0.15-0.25 0.15-0.25 0.15-0.25 0.15-0.25 0.15-0.25 0.15-0.25 0.15-0.25
Defoming agent 0.08-0.12 0.08-0.12 0.08-0.12 0.08-0.12 0.08-0.12 0.08-0.12 0.08-0.12 0.08-0.12
DM Water 0.4-0.6 0.4-0.6 0.4-0.6 0.4-0.6 0.4-0.6 0.4-0.6 0.4-0.6 0.4-0.6
TOTAL 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00

The wt.% levels and the monomers and reagents together with the variants scoped are all tested to provide for the desired results.
Preparation of adhesives:
Adhesives samples were prepared using above eight emulsion polymers as binder as follows:
TABLE NO: 2
Raw Material description Exp
Reactor charge, Add under agitation at 150-160 RPM
DMW 5.9-8.9
Fully hydrolysed Poly vinyl alcohol 1.5-2.5
Heat to 90°C & wait for 90 minutes
Add
Defoamer 0.2
Mix for 20 minutes
Mix separately
Polysaccharide powder 0.6-1.0
DMW 0.8-1.2
Add into reactor & mix for 15 minutes, cool to 70°C then add,
VAE emulsion polymer 8-12
Mix for 15 minutes, cool to 60°C then add,
PVAc emulsion in accordance with the present invention 60-85
Mix for 30 minutes, then add
Anti-freezing agent 0.08-0.12
Mix for 15 minutes then add,
Plasticizing agent 0.4-0.6
Wetting agent 0.15-0.25
Mix for 10 minutes, cool & add below 45°C
In-can preservative 0.25-0.35
Anti-fungal agent 0.08-0.12
Mix for 20 minutes, then add
Wetting agent 1 0.08-0.12
Wetting agent 2 0.25-0.35
Coalescing solvent 0.8-1.2
Total 100

Conventional adhesive preparing process was involved by employing VAE (vinyl acetate/ ethylene) emulsion polymer together with the Polyvinyl acetate of the present invention, as in the above table.
The variants scoped have been tested in the laboratory to meet the requirements of the present invention.
Lap shear strength of adhesives checked on Tinius UTM instrument as per EN 204 test method for D2 and D3 criteria on beach wood panels. Wood specimen used are of beach wood with dimension 20 mm*80 mm*06 mm

TABLE NO: 3
IBOMA addition stage Lap shear strength tested for adhesives as per EN 204 (N/m2)
7 days dry in STD atmosphere 7 days dry in STD atmosphere + 4 days in water at (20+/-5) °C 7 days dry in STD atmosphere + 4 days in water at (20+/-5) °C + 7 days dry in STD atmosphere
Throughout 11.0 1.064 8.55
In seed only 11.1 0.605 4.31
After seed 12.0 0.693 8.44
After 1 hour 11.7 1.17 6.00
After 2 hours 11.7 1.22 7.23
After 3 hours 12.7 1.32 7.34
After 4 hours 15.2 1.49 11.2
Without IBOMA 12.0 0.707 8.35

Mainly the select monomers of the reactor charge involved in the process for the synthesis of polyvinyl acetate based polymeric emulsion/adhesive based on power feed technique whereby during synthesis of emulsion polymer, addition of Isobornyl methacrylate into monomer mix when happens especially after completion of 240 minutes addition of monomer mix and rest 60 minutes of monomer mix is added containing Isobornyl methacrylate of the 300 minutes procedure for 100 gms emulsion polymer batch size, all contributes towards the Isobornyl methacrylate monomer based moiety to remain protruding outside the polymer particle with the polymer particle surface having more of Isobornyl methacrylate, thereby providing improved adhesive strength to such polymer emulsion/adhesive without any external crosslinkers as well as metal catalysts.

In demonstrated examples, at initial stage, the reactor charge does not involve Isobornyl Methacrylate. It is added after completion of 240 minutes of monomer mix addition into reactor. This process of delayed addition of Isobornyl methacrylate in monomer mix during emulsion polymerization & performance characteristic of improved adhesive strength of the adhesive thus attained of the present emulsion polymer clearly goes to show under Table 3 above, that improved adhesive strength could be only attained of the emulsion polymer where the addition of Isobornyl methacrylate in monomer mix was delayed to after 4 hrs and continued for 1 more hour of total 5 hours addition of the monomer mix to thereby result in polyvinyl acetate based polymeric emulsion/adhesive comprising polymeric emulsion of cross linker free copolymer particle of monomers including vinyl acetate monomer, di-functional monomer, silane functional monomer, Isobornyl methacrylate monomer together with hydrolyzed polyvinyl alcohol, with said copolymer particle having Isobornyl methacrylate monomer based moiety protruding outside of or on the surface of said polymer particle displaying wet adhesive strength upto 1.5 N/m2.

It is thus possible for the present advancement to provide for improved polyvinyl acetate based adhesive with improved wet adhesive strength free of external crosslinkers based on a process as disclosed again based on emulsion polymerization free of any metal catalyst and said external crosslinkers.