Aqueous dispersion composition

Abstract

1. A method for preparing an aqueous dispersion composition made using an extruder-based continuous process, comprising: (A) providing an extruder; (B) feeding a mixture of (i) at least one vinyl acetate copolymer, (ii) at least one compatibilizer, and a dispersing agent to the extruder; (C) feeding a first water addition to the mixture of step (B) in the extruder to provide a polymer continuous dispersion; (D) feeding at least one base to the mixture of step (C) in the extruder to neutralize any available acid present in the mixture of step (C); and (E) feeding a second water addition to the mixture of step (D) in the extruder to provide a phase inversion to form a water continuous dispersion.

Description

Technical Field

[0001] The present invention relates to an aqueous dispersion composition useful as a heat seal coating (HSC), and more specifically, the present invention relates to an aqueous dispersion composition useful as an HSC produced by a continuous extruder-based phase inversion process.

Background Art

[0002] In the food and industrial packaging industries, polymer packaging is typically heat sealed at low temperatures (e.g., less than 150 degrees Celsius [<]) using an adhesive composition, and at low temperatures, the adhesive composition (1) is stable, (2) has a suitable particle size and particle size distribution, (3) can be easily applied to a substrate and has viscosity and rheological properties such that it can be coated on the substrate to provide a uniform heat seal coating, (4) is environmentally considerate, and (5) meets food contact regulatory requirements so as to be suitable for food packaging.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Heretofore, various emulsification processes under various process conditions (e.g., high temperature and high pressure) have been used to prepare low-temperature heat-seal compositions for use as emulsion adhesive products, such as those disclosed in CN108084370A, CN108148215A, and CN108102472A. Further, a continuous extruder-based direct dispersion process has been used to prepare aqueous ethylene-vinyl acetate copolymer (EVA copolymer)-based heat-seal products, where the polymer melt blend contacts an aqueous stream containing a neutralizing agent, water, and a surfactant in the emulsification zone of the extruder to form a dispersion. However, the above direct emulsification process has suffered from one or more of the problems, such as, for example, the emulsion produced by this process having a broad particle size distribution, which can cause yellowing, potential reduction in storage life stability, non-uniform particle composition between particles, etc. In view of the above existing problems with prior art emulsions and processes, it would be desirable to provide a dispersion composition that can be used as a heat-seal coating that does not have the above problems.

[0004] The present invention relates to a novel aqueous vinyl acetate copolymer dispersion composition useful as an HSC. According to one preferred embodiment of the present invention, the vinyl acetate copolymer can include, for example, an ethylene vinyl acetate (EVA) copolymer dispersion composition. In another preferred embodiment, the dispersion composition can include the following components: (a) at least one vinyl acetate copolymer, (b) at least one compatibilizer, (c) at least one alkyl carboxylic acid as a dispersant after neutralization, (d) a first addition of water to provide a polymer continuous dispersion, (e) at least one base added to neutralize available acids other than the water addition that continues to provide a polymer continuous system, and (f) a second addition of water to provide an inversion to a water continuous dispersion.

[0005] In another embodiment, the present invention includes a method for producing an aqueous vinyl acetate copolymer dispersion composition useful as an HSC, the method including producing the dispersion using a continuous extruder-based phase inversion process. The method is advantageous because it can produce a dispersion having a smaller particle size and a narrower particle size distribution with a smaller amount (e.g., < 1.5 weight percent [wt%]) of surfactant than a direct emulsification process using a continuous extruder. The use of an increased amount (e.g., > 2 wt%) of surfactant can have an adverse effect on the application performance of the resulting dispersion product, such as a decrease in water resistance and durability performance due to surface migration of the surfactant.

[0006] In yet another embodiment, the present invention includes an HSC prepared from the above dispersion composition and a substrate containing the HSC on at least a portion of the surface of the substrate.

[0007] In still another embodiment, the present invention includes food and industrial packaging materials heat-sealed with the above HSC, and heat-sealed articles prepared with the above HSC composition.

Embodiments for Carrying Out the Invention

[0008] As used herein, a "compatibilizer" means a resin having a viscosity of > 1 Pascal second (Pa·s) at 170 °C, an acid value of 50 milligrams of potassium hydroxide (KOH) (mg KOH / g resin) to 200 mg KOH / g resin per gram of resin, and a melting point above 100 °C.

[0009] As used herein, a "dispersant" means a fatty acid, a soap formed in situ.

[0010] As used herein, a "neutralizing agent" means a compound used to neutralize an acid such as the alkyl carboxylic acid described herein. Examples of neutralizing agents include, for example, KOH, ammonia, NaOH, amines, and mixtures thereof.

[0011] The water in this specification means deionized (DI) water that is suitable for use in preparing the aqueous dispersion of the present invention.

[0012] In a broad embodiment, the dispersion composition of the present invention comprises: (a) at least one vinyl acetate copolymer, such as EVA; (b) at least one compatibilizer; (c) at least one dispersant; (d) a first addition of water to provide a polymer continuous dispersion; (e) at least one base added to neutralize available acids other than the water addition that continues to provide a polymer continuous system; and (f) a second addition of water to provide an inversion to a water continuous dispersion.

[0013] The vinyl acetate copolymer compounds used to prepare the dispersion composition of the present invention include, for example, one or more vinyl acetate copolymer compounds known in the art. For example, the copolymer compounds include ethylene vinyl acetate copolymer (EVA), vinyl acetate ethylene copolymer (VAE), vinyl acetate acrylate copolymer, and other vinyl acetate copolymers such as vinyl acetate - ethylene - styrene copolymer, and mixtures thereof.

[0014] The amount of the copolymer compound used to prepare the dispersion composition of the present invention is, for example, 50 wt% to 90 wt% of the total solids content in one embodiment, 80 wt% to 90 wt% in another embodiment, and 85 wt% to 90 wt% in yet another embodiment.

[0015] Some examples of the advantageous properties exhibited by the vinyl acetate copolymer compound can include better adhesion to polyethylene terephthalate (PET), foil, and other substrates.

[0016] In another embodiment, the copolymer is produced, for example, by using a monomer containing an oxygen element as one of the monomers (i.e., a comonomer with vinyl acetate comonomer). For example, the comonomer is selected from one or more of the following compounds in addition to alkenes such as ethylene: vinyl acetate, acrylate, methacrylate, acrylonitrile, etc., and mixtures thereof.

[0017] When used with vinyl acetate comonomer, the amount of the comonomer compound is, for example, 5 wt% to 70 wt% in one embodiment, 10 wt% to 50 wt% in another embodiment, 15 wt% to 40 wt% in yet another embodiment, and 15 wt% to 30 wt% in still another embodiment.

[0018] The compatibilizer compounds used to prepare the dispersion composition of the present invention include, for example, one or more compatibilizer compounds known in the art. For example, in one embodiment, the compatibilizer compounds include rosin acid, rosin ester, terpene phenol, pure monomer resin, and phenolic resin, or mixtures thereof.

[0019] Generally, the compatibilizer compound has a viscosity of >1 Pa·s at 170°C in one embodiment, 1 Pa·s to 20 Pa·s in another embodiment, and 5 Pa·s to 8 Pa·s in yet another embodiment. The viscosity of the compatibilizer is measured by any well-known means, such as using a conventional viscometer, for example, a Brookfield thermocell.

[0020] Generally, the compatibilizer compound has an acid value of 10 mg KOH / g resin to 250 mg KOH / g resin in one embodiment, 50 mg KOH / g resin to 200 mg KOH / g resin in another embodiment, 100 mg KOH / g resin to 200 mg KOH / g resin in yet another embodiment, 125 mg KOH / g resin to 200 mg KOH / g resin in still another embodiment, and 140 mg KOH / g resin to 180 mg KOH / g resin in yet another embodiment. The acid value of the compatibilizer can be measured by any conventional titration method.

[0021] The melting points of the compatibilizer compounds include, for example, in one embodiment, above 40°C, in another embodiment, 50°C to 200°C, in yet another embodiment, 100°C to 200°C, and in still another embodiment, 120°C to 180°C. The melting point of the compatibilizer can be measured by any well-known means. For example, the melting point of the compatibilizer of the present invention is measured by the conventional differential scanning calorimetry (DSC) method.

[0022] The amount of the compatibilizer compound used to prepare the dispersion composition of the present invention includes, for example, in one embodiment, 5% to 30% by weight of the total solid content, in another embodiment, 9% to 20% by weight, in yet another embodiment, 9% to 15% by weight, and in still another embodiment, 9% to 12% by weight.

[0023] Some of the advantages of using the compatibilizer compound include, for example, that the compatibilizer provides an easy interaction between the EVA polymer and the dispersant, and the compatibilizer provides an easy interaction between the EVA polymer and the substrate, and as a result, an improvement in the bonding performance can occur.

[0024] The dispersant or dispersant compound used to prepare the dispersion composition of the present invention includes, for example, one or more dispersants known in the art. For example, in one embodiment, the dispersant includes alkyl carboxylic acids, oleic acid (fatty acid, soap formed in situ), dimer acids, other alkyl carboxylic acids having >12 to <20 carbon atoms per acid, and mixtures thereof.

[0025] The concentration of the dispersant used to prepare the dispersion composition of the present invention includes, for example, in one embodiment, <2% by weight solids of the formulation, in another embodiment, <1.5% by weight, in yet another embodiment, <1% by weight, in still another embodiment, 0.66% to 1% by weight, and in still another embodiment, 0.66% to 0.75% by weight.

[0026] Some examples of the advantageous properties exhibited by a dispersant when the dispersant is appropriately selected and is in an appropriate amount include: (1) providing stability to the polymer particles in the dispersion, and (2) providing a balance between the surface tension and the wetting ability of the dispersion on a substrate.

[0027] The method for making the dispersion composition of the present invention may include one or more additions of water to the composition. For example, in one preferred embodiment, a first water addition is added to the composition in an amount sufficient to form a polymer continuous dispersion.

[0028] For example, the amount of the first water addition is, based on the total solids and water, in one embodiment 3.5 wt% to 6 wt%, in another embodiment 3.5 wt% to 5 wt%, and in yet another embodiment 3.5 wt% to 4.5 wt%.

[0029] The dispersion composition of the present invention includes another base for neutralizing the available acid in the composition and for continuing to provide a polymer continuous system. The base compounds used to prepare the dispersion composition of the present invention include, for example, one or more bases known in the art. For example, the neutralizing agent or base compound includes aqueous potassium hydroxide (KOH), sodium hydroxide (NaOH), ammonia, and mixtures thereof. In one preferred embodiment, the base compound is, for example, KOH having a concentration of 10 wt% to 90 wt%, in another embodiment 20 wt% to 90 wt%, and in yet another embodiment 40 wt% to 50 wt%.

[0030] The amount of the base used to prepare the dispersion composition of the present invention is, for example, in one embodiment, neutralization of 70 percent (%) to 130% of the theoretical acid value of the components, in another embodiment 80% to 120%, in yet another embodiment 90% to 110%, and in still another embodiment 90% to 100%.

[0031] Some examples of the advantageous properties exhibited by the base may include neutralization for stabilizing the polymer particles.

[0032] As described above, the method for preparing the dispersion composition of the present invention involves one or more additions of water to the composition. In a preferred embodiment, a second water addition is made to the composition in an amount sufficient to phase invert, for example, into a water continuous dispersion.

[0033] For example, the amount of the second water addition is, in one embodiment, > 3.5 wt%, in another embodiment 20 wt% - 90 wt%, in yet another embodiment 30 wt% - 70 wt%, and in still another embodiment 40 wt% - 60 wt%, based on (1) the total solids, (2) the first water addition, and (3) the second water addition.

[0034] The dispersion composition of the present invention may also contain other additional optional compounds or additives, and such optional compounds can be added to the composition in combination with one or more of components (a) to (f). Optional additives or agents that can be used to prepare the dispersion composition of the present invention include, for example, one or more optional compounds known in the art for their use or function. For example, optional additives include, but are not limited to, defoamers, rheology modifiers, wetting agents, and mixtures thereof.

[0035] When used to prepare the dispersion composition of the present invention, the amount of the optional compound includes, for example, 0 wt% - 5 wt% in one embodiment, 0.001 wt% - 3 wt% in another embodiment, 0.01 wt% - 2 wt% in yet another embodiment, and 0.1 wt% - 1 wt% in still another embodiment.

[0036] In a general embodiment, a method for preparing the dispersion composition of the present invention includes the steps of mixing (a) at least one vinyl acetate copolymer, such as EVA, (b) at least one compatibilizer, (c) at least one dispersant, (d) a first addition of water to provide a polymer continuous dispersion, (e) at least one base added to neutralize available acids other than the water addition that continues to provide a polymer continuous system, and (f) a second addition of water to provide a phase inversion to a water continuous dispersion, for example, by melt blending.

[0037] Generally, the process equipment and auxiliary equipment useful in the present invention for forming a homogeneous melt blend can include any means and any conditions typically used for melt blending thermoplastic resins, and are known to those skilled in extruder-based processes. For example, the equipment that can be used in the present invention includes heat exchangers, back pressure regulators, melt pumps, gear pumps, kneaders, BANBURY (registered trademark) mixers, rotor stator mixers, single screw extruders, twin screw extruders, multi-screw extruders, and the like.

[0038] Furthermore, various schemes for setting up the process equipment can be used. For example, in one embodiment, a first mixing device is used in combination with a second mixing device. For example, in some embodiments, the first mixing device is, for example, a kneader, a BANBURY (registered trademark) mixer, a single screw extruder, or a multi-screw extruder, and the second mixing device is an extruder such as a twin screw extruder having a plurality of heating zones. For example, in other embodiments, the first mixing device is an extruder such as a twin screw extruder, and the second mixing device is a rotor stator mixer.

[0039] In another embodiment, a twin-screw extruder having a plurality of heating zones with a single extruder, for example, auxiliary equipment such as a back pressure regulator, a melt pump, or a gear pump, is used to produce the aqueous dispersion composition of the present invention. For example, in various embodiments, the extruder may have various zones including, for example, (1) a conveying, melting, and mixing zone, (2) an emulsifying zone, and (3) a dilution zone, and the different zones may be operated at a predetermined temperature. In some embodiments, the conveying, melting, and mixing zone portion of the extruder may have a barrel with a length "L" and a diameter "D", and the length-to-diameter ratio (L / D) used is, for example, in one preferred embodiment, 12 to 1 or more, for example, 12 to 1 to 60 to 1. In some preferred embodiments, the above-described extruder-based process used in the present invention is described in more detail, for example, in U.S. Provisional Patent Application No. 62 / 579,354 filed on October 31, 2017 by Escobar Marin et al.

[0040] In another embodiment, the aqueous dispersion composition is prepared using, for example, an extruder-based continuous process by the following general method: The components (a) to (f) of the composition of the present invention are fed into an extruder using, for example, a feeder at a controlled rate. As described above, any conventional extruder can be used in the present invention. In one embodiment, the extruder includes, for example, a twin-screw extruder with a diameter of 25 millimeters (mm) having an L / D ratio as described above. The feed rate in grams per minute (g / min) of components (a) to (f) is, for example, 60 g / min to 150 g / min in one embodiment. The components of the present invention are sent through the extruder and melted to form a liquid melt material.

[0041] The temperature profile of the extruder can be raised to a predetermined temperature. For example, the rising temperature is 70°C to 240°C in one embodiment and 120°C to 150°C in another embodiment. Next, water is supplied to the extruder at a predetermined rate, for example, at a rate of 1.0 g / min to 2.0 g / min in one embodiment. Following the water supply, a neutralizing agent is supplied to the extruder at a predetermined rate, for example, at a rate of 1.4 g / min to 2.4 g / min in one embodiment, using a second introduction site of the extruder. The phase-inverting water is supplied to the extruder through the inlet position of the extruder after the neutralizing agent, and water is supplied to the extruder at a predetermined rate, for example, at a rate of 1.0 g / min to 8.0 g / min in one embodiment. Dilution water is also supplied to the extruder at a predetermined rate, for example, at a rate of 20 g / min to 90 g / min in one embodiment, using two separate pumps at one or two inlet positions (the first and second inlet positions) of the extruder. The temperature profile of the extruder is cooled back to a temperature, for example, below 100°C near the end of the extruder. At the extruder outlet, a back pressure regulator is used to adjust the pressure in the extruder barrel to a pressure adapted to reduce steam formation. Generally, in one embodiment, the pressure in the extruder barrel is, for example, 2 megapascals [MPa] to 4 MPa.

[0042] After the above method steps, the resulting aqueous dispersion product exits the extruder. Next, in one preferred embodiment, the aqueous dispersion is filtered through a 200 micron (μm) filter. The resulting filtered aqueous dispersion has a solids content measured in weight percent (wt%), and the solid particles of the dispersion have a volume average particle size measured in microns. For example, the solids content of the dispersion is 30 wt% to 50 wt% in one embodiment, and the particle size of the particles in the dispersion is 0.9 μm to 2.0 μm in one embodiment. In some embodiments, the particle size mode can also be recorded. The solids content of the aqueous dispersion is measured using conventional equipment, such as an Ohaus® MB45 infrared solids analyzer (available from Ohaus Corporation), and the particle size of the solid particles of the aqueous dispersion is also measured using conventional equipment, such as a Coulter® LS-230 particle size analyzer (available from Beckman Coulter Corporation). In one preferred embodiment, the solids content of the dispersion and the average particle size (PS) of the solid particles are as described in Table IV of the examples.

[0043] In one embodiment, the aqueous dispersion composition is, for example, an aqueous dispersion composition that does not contain wax. In a preferred embodiment, the wax-free aqueous dispersion composition is prepared, for example, using an extruder-based continuous process. The method steps are, for example, (A) A method step of providing an extruder, and (B) (i) At least one vinyl acetate copolymer, (ii) at least one compatibilizer, and a method step of feeding a mixture of a dispersant to the extruder, and (C) A method step of supplying a first water addition to the mixture of step (B) in the extruder to provide a polymer continuous dispersion, and (D) A method step of supplying at least one base to the mixture of step (C) in the extruder to neutralize any available acid present in the mixture of step (C), and (E) A method step of supplying a second water addition to the mixture of step (D) in the extruder to provide a phase inversion that forms a water continuous dispersion, and includes.

[0044] In another embodiment, step (B) of the above method can be separated into two steps. For example, (i) at least one vinyl acetate copolymer and (ii) at least one compatibilizer are first mixed together to form a mixture, and then the mixture is fed as a stream into an extruder, and at least one dispersant is fed into the extruder as a separate stream.

[0045] The dispersion composition of the present invention prepared according to the above method has several beneficial properties, for example, including small particle size and narrow particle distribution, and such properties advantageously result in, for example, good coating appearance, good coating uniformity, better storage stability, and a preferred solids content.

[0046] For example, the solids content of the dispersion of the present invention is 20% solids to 80% solids in one embodiment, from 30% solids to 70% solids in another embodiment, and from 35% solids to 55% solids in yet another embodiment. The solids content of the dispersion can be measured, for example, by an Ohaus MB45 infrared moisture analyzer (available from Ohaus Corporation) or by a hot oven. In a preferred embodiment, the solids content of the dispersion is measured by the above moisture analyzer.

[0047] For example, the viscosity characteristics of the dispersion of the present invention are from 10 millipascal seconds (mPa·s) to 100 mPa·s in one embodiment, from 20 mPa·s to 60 mPa·s in another embodiment, and from 30 mPa·s to 50 mPa·s in yet another embodiment. The viscosity characteristics of the dispersion are measured, for example, using a Brookfield DV-II+ (available from Brookfield).

[0048] For example, in one embodiment, the particle size of the particles in the dispersion of the present invention is from 0.2 microns (μm) to 6 μm, in another embodiment from 0.3 μm to 4 μm, and in yet another embodiment from 0.4 μm to 2 μm. The particle size of the dispersion can be measured by any well-known particle size measuring instrument. In one embodiment, the particle size of the dispersion is measured using, for example, a Beckman Coulter LS13 320 instrument.

[0049] In addition to the above characteristics, the performance of the dispersion composition is evaluated, for example, from the perspective of storage stability and tested under accelerated temperature aging at 45°C and refrigeration conditions. For example, the storage stability of the dispersion of the present invention is evaluated by recording the weekly phase separation and viscosity of the dispersion by aging in (1) a refrigerated (4°C) environment and (2) a heated (45°C) oven. If the dispersion precipitates and separates into two layers, or there is a significant change in viscosity exceeding 100%, or it becomes gelatinous (i.e., gelation occurs), the storage stability of the dispersion is unstable.

[0050] Next, the overall stability of the dispersion can be compared with commercially available products produced using a batch process. In one embodiment, the dispersion is evaluated to have, for example, "good" storage stability or "worse" storage stability compared to batch process products. For example, "good" storage stability means that the performance of the dispersion is the same as or better than that of commercially available products of the batch process, and "worse" storage stability means that the performance of the dispersion is worse than that of commercially available products of the batch process.

[0051] As described above, when the dispersion composition of the present invention is prepared, the dispersion composition can be used as an HSC for various applications. For example, in one embodiment, an HSC can be formed on a substrate such as a film for food packaging using the HSC dispersion composition, and then the film substrate can be heat-sealed.

[0052] The HSC dispersion composition can be applied to a substrate using various conventional coating methods such as gravure coating, Meyer rod coating, curtain coating, air knife coating process, flexographic printing process, and offset printing process.

[0053] The dispersion composition of the present invention provides an HSC that can be advantageously used for various applications such as heat-sealing food and industrial packaging. The HSC of the present invention also exhibits several beneficial properties including, for example, good coating appearance, high bond strength, and high hot tack, and no yellowing.

[0054] For example, in one embodiment, the appearance of a coating formed from the HSC dispersion of the present invention is evaluated by visually observing the coating of the present invention and comparing the HSC coated on a PET film with a batch process HSC. The appearance of the HSC can be reported, for example, according to the following evaluation system: HSC having a "good" coating appearance as determined by visual observation versus HSC having an "oily" coating appearance as determined by visual observation. An HSC having a "good" coating appearance is a coating that has been observed to have a gloss within an acceptable range and a good smooth coating, and an "oily" coating appearance is an HSC that has been observed to have an ugly oily appearance and is not within the acceptable range. Further, HSCs made using a conventional batch process may also not have the appearance of "yellowing", but instead may have an undesirable "yellow" color or may appear unclear when compared to HSCs made according to the present invention that have been observed to have a clear coating.

[0055] For example, in one embodiment, the sealing performance of the HSC of the present invention is better than that of the batch process in terms of bonding strength. For example, the bonding strength of the HSC of the present invention is 20% to 300% better than that of the batch process in one embodiment, 50% to 200% better than that of the batch process in another embodiment, 60% to 150% better than that of the batch process in yet another embodiment, and 70% to 100% better than that of the batch process in still another embodiment. The sealing characteristics of the HSC are measured, for example, by a bonding test as described in the following examples of this specification.

[0056] For example, in one embodiment, the hot tack characteristics of the HSC of the present invention are better than those of the batch process. For example, the hot tack characteristics of the HSC of the present invention are 10% to 200% better than those of the batch process in one embodiment, 20% to 150% better than those of the batch process in another embodiment, 25% to 100% better than those of the batch process in yet another embodiment, and 30% to 80% better than those of the batch process in still another embodiment. The hot tack characteristics of the HSC are measured, for example, using a temperature-controlled Instron testing instrument operated at a speed of 200 millimeters per second (mm / sec) in accordance with ASTM F1921, Test Method B.

[0057] As described above, the dispersion composition can be used to produce HSCs for food packaging articles. Other uses for which the dispersion composition can be used include, for example, industrial skin packaging and medical packaging applications. The invention described in the original claims of the present application is appended below. [1] A method for producing an aqueous dispersion composition produced using an extruder-based continuous process, comprising: (A) providing an extruder; (B) feeding a mixture of (i) at least one vinyl acetate copolymer, (ii) at least one compatibilizer, and a dispersant to the extruder; (C) supplying a first addition of water to the mixture of step (B) in the extruder to provide a polymer continuous dispersion; (D) supplying at least one base to the mixture of step (C) in the extruder to neutralize any available acid present in the mixture of step (C); (E) supplying a second addition of water to the mixture of step (D) in the extruder to provide an inversion to form a water continuous dispersion. [2] The method according to [1], wherein each of the components (i) at least one vinyl acetate copolymer, (ii) at least one compatibilizer, and (iii) at least one dispersant is separately fed to the extruder. [3] The method according to [1], wherein the components (i) at least one vinyl acetate copolymer, (ii) at least one compatibilizer, and (iii) at least one dispersant are fed to the extruder together. [4] The method according to [1], wherein the extruder has a first feed zone near the front end of the extruder, a second feed zone near the middle of the extruder, and a third feed zone near the rear end of the extruder. [5] The method according to [1], wherein the temperature of the first feed zone is 90°C to 150°C. [6] The method according to [1], wherein the temperature of the second feed zone is 90°C to 150°C. [7] The method according to [1], wherein the temperature of the third feed zone is 80°C to 150°C. [8] The method according to [1], wherein the dispersion produced by the method has a storage stability of more than one year at room temperature and a particle size of less than 2 microns. [9] The method according to [1], wherein the at least one vinyl acetate copolymer is an ethylene vinyl acetate copolymer and is fed to the extruder at a concentration of 50% to 90% by weight of the total solids.

[10] The method according to [1], wherein the at least one compatibilizer is highly dimerized rosin acid and is supplied to the extruder at a concentration of 5 wt% to 30 wt% of the total solids.

[11] The method according to [1], wherein the at least one dispersant is oleic acid and is supplied to the extruder at a concentration of 0.1 wt% to 5 wt% of the total solids.

[12] The method according to [1], wherein the amount of water supplied to the extruder for the first water addition is 3.5 wt% to 6 wt% of the total solids and the first water addition.

[13] The method according to [1], wherein component (e), which is the at least one base, is potassium hydroxide and is supplied to the extruder at a concentration of 80% to 120% neutralization of the theoretical acid value of the component.

[14] The method according to [1], wherein the amount of water supplied to the extruder for the second water addition is 3.5 wt% or more of the total solids, the first and the second water additions.

[15] The method according to [1], wherein the aqueous dispersion composition does not contain wax.

[16] A heat-seal coating for food packaging or industrial packaging, comprising the dispersion composition produced by the method according to [1].

Example

[0058] The following examples are presented to explain the present invention in more detail, but should not be construed as limiting the scope of the claims. All parts and percentages are by weight unless otherwise indicated.

[0059] The various terms and designations, as well as the raw materials or components, used in the following Invention Examples (Inv. Ex.) and Comparative Examples (Comp. Ex.) of the present invention are listed in Table I.

Table 1

Table 2

Table 3

Table 4-1

Table 4-2

[0060] Comparative Examples A - D General Procedure for Preparing the Dispersion In Comparative Examples A - D, an aqueous dispersion was prepared using the following general procedure. Components 1 to 3 listed in Table IV were fed into a twin-screw extruder with a diameter of 25 mm using a feeder at a controlled speed, and a feed rate in units of g / min was used as described in Table IV. Components 1 to 3 were passed through the extruder and melted to form a liquid molten material.

[0061] The extruder temperature profile was raised to the temperature described in the "Polymer Melting Zone" column of Table IV. Water and / or a neutralizing agent were mixed together and fed into the extruder at the feed rate described in Table IV for neutralization at the initial water introduction site. Next, dilution water was fed into the extruder at the feed rate described in Table IV using two separate pumps at one inlet position or two separate inlet positions (the first and second inlet positions). The temperature profile of the extruder was cooled back to a temperature below 100 °C near the end of the extruder. At the extruder outlet, a back pressure regulator was used to adjust the pressure inside the extruder barrel to a pressure adapted to reduce steam formation.

[0062] An aqueous dispersion product exited the extruder. The aqueous dispersion was filtered through a 200 μm filter. The resulting filtered aqueous dispersion had a solids content measured in weight percent (wt%), and the solid particles of the dispersion had a volume average particle size (V 平均 PS) and were recorded in Table IV. In some cases, the particle size mode was also recorded. The solids content of the aqueous dispersion was measured using an infrared solids analyzer, and the particle size of the solid particles of the aqueous dispersion was measured using a Coulter LS-230 particle size analyzer (available from Beckman Coulter Corporation). The solids content of the dispersion and the average particle size (PS) of the solid particles are described in Table IV.

[0063] Examples 1 and 2, and Comparative Examples E to I In the examples of the present invention and 2, as well as Comparative Examples E to I, after raising the temperature profile of the extruder to the temperature described in the "Polymer Melt Zone" column of Table IV, an aqueous dispersion was prepared using the general procedure for preparing the dispersions described in Comparative Examples A to D above, except that water and the neutralizing agent were separately supplied to the extruder. Water was supplied to the extruder at the rate described in Table IV, and subsequently, the neutralizing agent was supplied at the rate described in Table IV at the second introduction site. After the neutralizing agent, inverse-phase water was supplied to the extruder at the inlet position of the extruder.

[0064] Characteristic Measurement Solid Content Measurement The solid content of the dispersion was measured using an Ohaus MB45 infrared moisture analyzer. The analyzer was set to 150 °C, and the measurement completion was set to a loss of <1 milligram (mg) in 90 seconds (s).

[0065] Viscosity Measurement The viscosity of the dispersion was tested using a Brookfield DV-II+. Measurements were taken at 20 revolutions per minute (RPM) and 25 °C using an RV spindle.

[0066] Particle Size Measurement The particle size of the dispersion was measured using a Beckman Coulter LS 13 320 instrument. A universal liquid module containing DI water was attached to the instrument, and the data was analyzed using an optical model with a fluid refractive index of 1.332 and a sample refractive index of 1.5 real and 0 imaginary.

[0067] Performance Evaluation Test All the performance of the dispersion composition was evaluated by comparing the performance of the dispersion with that of a commercially available product produced by a batch process. The "commercially available product of the batch process" is available as Adcote 37JD1198 from The Dow Chemical Company.

[0068] The dispersion sample was manually coated onto the substrate using a Meyer rod drawdown bar and the drawdown method, and the dry coating weight was approximately 5.5 - 6.0 g / m 2It was adjusted to. After the drawdown, the wet coating was dried in an oven at 90 °C for about 2 minutes (min).

[0069] Storage stability The storage stability of the dispersion was evaluated by recording the weekly phase separation and viscosity in (1) a refrigerated (4 °C) environment and (2) a heated (45 °C) oven aging. The overall stability of each of the dispersions was compared with a commercially available product of the batch process, and the results were reported according to the following evaluation system: A dispersion having "good" storage stability means that the performance of the dispersion is the same as that of a commercially available product of the batch process, and "worse" storage stability means that the performance of the dispersion is worse than that of a commercially available product of the batch process.

[0070] Appearance of the coating The appearance of the HSC formed from the dispersion on the PET film was visually observed and compared with Adcote37JD1198. The appearance of the coating was reported according to the following evaluation system: An HSC having a "good" coating appearance was observed to have a gloss within the allowable range and a good smooth coating, and an "oily" coating appearance was observed to have an ugly oily appearance and was not within the allowable range.

[0071] Heat-sealing substrate The heat-sealing substrate was prepared by heat-sealing the primer substrate to the second substrate using the following method.

[0072] The primer substrate included commercially available 92 g PET and the pre-laminated PET-aluminum foil side.

[0073] The second substrate included commercially available 92 g PET, a 4-mil polyvinyl chloride (PVC) sheet, a 4-mil polyethylene terephthalate glycol (PETG) sheet, a 4-mil low-density polyethylene (LDPE) sheet, and an aluminum (Al) foil.

[0074] The dispersion composition of the present invention was coated on the surface of a primer substrate using a hand-drawdown procedure. Next, the primer substrate coated with the wet dispersion composition was brought into contact with a second substrate. The wet-coated primer substrate and the second substrate were dried in an oven at 90 °C for about 2 minutes. The coating weight to be dried was adjusted to 5.5 g / m 2 ~6.0 g / m 2 .

[0075] Bonding test of heat-seal substrate The bonding test of the heat-seal substrate was carried out at a pressure of 2.76 bar, a time of 1.0 second, and two different temperatures (93.33 °C and 121.11 °C).

[0076] The bonding test was carried out at a speed of 254 mm / min using a strip of the sealed area of 25.4 × 25.4 mm 2 . Three strips were tested for each sample and the average value was reported.

[0077] Hot tack of heat-seal substrate The hot tack measurement of the heat-seal substrate was carried out using a temperature-controlled Instron® instrument (available from Instron) at a speed of 200 mm / sec according to the method described in ASTM F1921, Test Method B.

[0078] Stability of shelf life To evaluate the stability of the shelf life, samples were stored at 4 °C (in a refrigerator) and at 45 °C (in an oven) for various periods. The stability of the shelf life of the samples was tested by visual observation, and the results of the test are summarized in Table V.

Table 5

[0079] The stability of the shelf life regarding the viscosity of the dispersion after storing the samples at 4 °C (in a refrigerator) and at 45 °C (in an oven) for various periods is summarized in Table VI.

Table 6

[0080] Samples of Comparative Example H and Comparative Example I produced a hazy oily coating appearance, so no further bond strength tests were performed on the samples of Comparative Example H and Comparative Example I.

Table 7

Table 8

Table 9

Claims

1. A method for producing an aqueous dispersion composition produced using an extruder-based continuous process, comprising: (A) providing an extruder; (B) feeding into the extruder a mixture of (i) at least one vinyl acetate copolymer, (ii) at least one compatibilizer, and a mixture with at least one dispersant; (C) feeding a first addition water to the mixture of step (B) in the extruder to provide a polymer continuous dispersion (first water addition step); (D) feeding at least one base to the mixture of step (C) in the extruder to neutralize any available acid present in the mixture of step (C); (E) feeding a second addition water to the mixture of step (D) in the extruder to provide an inversion to form a water continuous dispersion (second water addition step).

2. The method according to claim 1, wherein each of the components (i) at least one vinyl acetate copolymer, (ii) at least one compatibilizer, and (iii) at least one dispersant is separately fed to the extruder.

3. The method according to claim 1, wherein the components (i) at least one vinyl acetate copolymer, (ii) at least one compatibilizer, and (iii) at least one dispersant are fed to the extruder together.

4. The method according to claim 1, wherein the extruder has a first feed zone near the front end of the extruder, a second feed zone near the center of the extruder, and a third feed zone near the rear end of the extruder.

5. The method according to claim 4, wherein the temperature of the first feed zone is 90°C to 150°C.

6. The method according to claim 4, wherein the temperature of the second feed zone is 90°C to 150°C.

7. The method according to claim 4, wherein the temperature of the third feed zone is 80°C to 150°C.

8. The method according to claim 1, wherein the aqueous dispersion composition produced by the method has a storage stability of more than one year at room temperature and a particle size of less than 2 microns.

9. The method according to claim 1, wherein the at least one vinyl acetate copolymer is an ethylene vinyl acetate copolymer and is fed to the extruder at a concentration of 50% to 90% by weight of the total solids.

10. The method according to claim 1, wherein the at least one compatibilizer is highly dimerized rosin acid and is supplied to the extruder at a concentration of 5 wt% to 30 wt% of the total solids.

11. The method according to claim 1, wherein the at least one dispersant is oleic acid and is supplied to the extruder at a concentration of 0.1 wt% to 5 wt% of the total solids.

12. The method according to claim 1, wherein the amount of water supplied to the extruder in the first water addition step is 3.5 wt% to 6 wt% of the total weight of the total solids and the first added water.

13. The method according to claim 1, wherein the at least one base is potassium hydroxide and is supplied to the extruder at a concentration of 80% to 120% neutralization of the theoretical acid value.

14. The method according to claim 1, wherein the amount of water supplied to the extruder in the second water addition step is 3.5 wt% or more of the total weight of the total solids, the first added water and the second added water.

15. The method according to claim 1, wherein the aqueous dispersion composition does not contain wax.

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