WO2014100865A1

WO2014100865A1 - Primer composition for a gluing process, process of gluing an expanded eva component to a substrate, expanded eva component, use of the primer composition and expanded eva component, and product

Info

Publication number: WO2014100865A1
Application number: PCT/BR2012/000547
Authority: WO
Inventors: Vagner Giam DA ROSA REIS; Jenifer RITTER; Ana Cristina FONTES MOREIRA; Mauro alfredo SOTO OVIEDO; Camilo DELFINO; Raquel BECKER
Original assignee: Braskem S.A.; Kiling S/A Tintas E Adesivos; Dannemann, Siemsen, Bigler & Ipanema Moreira
Priority date: 2012-12-28
Filing date: 2012-12-28
Publication date: 2014-07-03
Also published as: AR094267A1

Abstract

The present invention describes a modified ethylene copolymer having polar monomers that can be used for producing an expanded ethylene-vinyl acetate-based component for the shoe sector which, along with a primer that also contains a modified copolymer, allows adhesives to be used directly on said material for gluing same to other substrates in the shoe industry, simplifying the gluing process and making same more economical and sustainable. More specifically, the present invention relates to a primer composition that can be used in the gluing process and to the use thereof, as well as to an expanded EVA component and process for gluing said EVA component to a substrate.

Description

DETAILED DESCRIPTION REPORT FOR "PRIMER COMPOSITION FOR COLLING PROCESS, COLLING PROCESS OF AN EXPANDED EVA COMPONENT, EXPANDED EVA COMPONENT, USE OF EXPANDED EVA COMPONENT, AND PRODUCT".

FIELD OF INVENTION

The present invention describes a polar monomer-modified ethylene copolymer for producing an expanded ethylene-vinyl acetate footwear segment component which, with a primer also containing a modified copolymer, enables the direct use of adhesives on said material to bonding to other substrates in the footwear industry, making the bonding process simplified, economical and sustainable.

DESCRIPTION OF TECHNICAL STATE

In the footwear industry, ethylene vinyl acetate polymer

(EVA) is widely used in the manufacture of expanded plates, braids, unisoles and footwear, as it has significant impact resistance and elongation at break, providing more comfort to consumers and reducing footwear weight.

The adhesion of the expanded EVA component to other parts of the shoe requires great care and attention, as the durability of a shoe depends directly on the quality of the adhesion process of its components.

Expanded EVA midsoles or unisoles can be prepared via plate pressing or injection. In these processes, the surface of the material is very smooth and uniform, especially in the product obtained by the injection process. This surface makes it difficult to bond, but specifically the adhesion and cohesion of EVA to other substrates, such as rubbers used in soles, leathers and / or synthetic components used in the manufacture of shoe leather.

In general, shoes fall into three main categories, depending on how the upper is fitted with the midsole. The largest category, and the most important in the footwear segment, includes shoes that are bonded by adhesives (over 50% of the total produced); the second category includes seam-linked shoes; and the last category is vulcanized shoes. Adhesive materials therefore represent a group of materials of great importance in shoe manufacturing.

In general, the most commonly used sole adhesives are polyurethanes (PU) dissolved in organic solvents or dispersed in water and may contain hardeners and various other compounds which, once mixed, become a single product. Thus, these materials are capable of joining two surfaces through adhesion force and internal cohesion without significantly modifying the structures of these bodies. They are largely responsible for the integrity of the entire structure of a shoe, as they maintain the cohesion or bonding between its various constituent elements.

Adhesion is understood to be the ability of an adhesive to wet and affinity to one or more substrates. The bonding force is based on the forces of attraction between the adhesive molecules and the surfaces to be bonded.

By cohesion is meant the internal strength of the materials themselves (primer, substrate and adhesive), ie the stronger the intermolecular forces, the greater the cohesion and hence the greater the peel strength.

In shoe manufacturing, the use of these two concepts (adhesion and cohesion) facilitates and speeds up the detection of glue failure, such as: (i) sole adhesion problems, (ii) leather adhesion problems, (iii ) leather-sole bonding problems and (iv) raw material problems in the leather and / or sole.

The performance of the PU-based adhesive is dependent on the w / 7 mer used, which comprises a liquid compound that is applied to a substrate prior to application of the adhesive or sealant, forming the intermediate layer between the substrate and the adhesive. The reasons for using the primers are varied and may include, alone or in combination, (i) protect surfaces after treatment (may be used to extend the time between bonding surface preparation and adhesive application); (ii) adjusting surface free energy, providing a surface that is more easily wetted than the substrate; (iii) dissolve low levels of organic contamination; (iv) promote the chemical reaction between the adhesive and the adhering surface (substrate); and (v) serve as an intermediate layer to improve physical properties by providing greater bonding strength. In addition, primers are used to penetrate porous or rough surfaces to provide better interlocking mechanics between the substrate and the adhesive as they have lower viscosity than adhesives. Therefore, priming is an essential step in the bonding process.

One of the first processes used for adhesion of expanded EVA midsole / unisole parts was to sand the surface of the part so that, with increasing roughness, a cold primer (without chemical surface change) could be applied and adhered. with PU-based adhesive could be made. It is worth noting that this procedure has several disadvantages, since sanding the substrate generates dust and industrial residues, in addition to increasing the failure rate of the glue, since the quality of the finish varies according to the ability of the substrate. worker who performs the process.

Currently in the shoe industry, ultraviolet (UV) curing primers and PU-based adhesives are used, especially for the preparation of conventional EVA resins. Such adhesion process comprises the steps of (1) cleaning the EVA, midsole / unisola (aqueous base or organic solvent); (2) application of UV primer (dipping or brush); (3) curing (activating) the primer by UV radiation (transforming the liquid formulation into a solid, dry, insoluble and infusible polymer by UV-activated polymerization and crosslinking reactions); (4) application of adhesive (PU base); and (5) shoe bonding (inter-joining / unisola-leather joint). In this process, one uses a primer that has UV-Activated Numbers and Primers With polymerization of the monomers, a thin film is formed and strongly interacts with the EVA surface. More specifically, the monomers penetrate the surface of the EVA component and, when polymerized with UV radiation, form tangled polymers in the EVA surface chains, resulting in high adhesion between the layers and allowing high performance bonding of the EVA component. EVA expanded with other footwear components after application of PU-based adhesive.

Despite offering excellent adhesion performance, this process depends on equipment that needs constant maintenance to ensure the intensity of UV radiation (need for periodic replacement of lamps due to their average lifetime, as well as accumulation of EVA dust on lamps), increasing the production cost of the footwear. Another disadvantage is that the high energy of UV radiation can cause color loss of colored substrates or cause yellowing of the EVA piece and the substances present in the primer, as well as the adhesive used in gluing the footwear. In addition, UV radiation can be harmful to equipment operators, either by direct exposure to light or ozone, which is formed when oxygen molecules in the air come into contact with highly irritating and toxic UV light, especially to the human respiratory system.

In addition to all of the above, it must also be considered that the adhesion process includes the costs associated with its steps and the fulfillment of quality control requirements, which is often the most critical issue. It is noteworthy that for EVA and PU type polymeric substrates, the UV-curing primer protects the substrate surface only until the adhesive is applied due to the dynamic and mobile nature of the polymeric molecule, as the treated surface molecules can return to the bulk of the polymer, rendering the adhesion process ineffective.

It is evident, therefore, that there is a constant concern to improve the technique of adhesion and cohesion between the EVA component ex- pandido and the different substrates (components) present in the footwear industry. However, from a commercial point of view, the state of the art does not disclose any competitive solution that guarantees an efficient bonding process for the good performance of the footwear and at the same time safe for the workers who perform this process.

In general, several methods are used for the EVA resin to present more similar polarity to PU, such as copolymerization of ethylene with other polar monomers, via polymerization or reactive extrusion process. Copolymerization of the monomers may be performed in tubular or autoclave reactor, bulk polymerization processes, or by emulsion polymerization.

Accordingly, GB 1443394 discloses a multi-stage tubular reactor ethylene copolymerization process for producing reactor copolymers, terpolymer and blends. More specifically, the copolymerization of ethylene and / or ethylene vinyl acetate copolymer is described with various comonomers such as maleic anhydride, butyl acrylate, methyl methacrylate, acrylonitrile, butyl methacrylate, N-isopropylacrylamide, N phenylmethacrylamide, among others.

JP60208946 describes a polar monomer (7-t-butyl fumarate) which can be copolymerized via radical polymerization with butadiene, ethylene and vinyl acetate, which is more reactive than maleic diesters. From this monomer it is then possible to obtain terpolymers of ethylene, vinyl acetate and the described monomer, thus making the resulting polymer more polar compared to an EVA polymer. Further, US3904571 and EP266994 which describe the preparation of a high adhesive resin composed of ethylene vinyl acetate copolymer resin, unsaturated dicarboxylic anhydrides, carboxylic acid esters and, if necessary, organic peroxide may be cited. . More specifically, these documents describe reactive extrusion processes of an EVA resin with anhydrides or unsaturated acids, whereby the polarity of the resin can be increased. US 3904571A describes the preparation of a higher tack resin, composed of ethylene vinyl acetate copolymer resin, unsaturated dicaboxylic anhydrides, carboxylic acid esters and if necessary organic peroxide. This patent relates to the reactive extrusion process of an EVA resin with unsaturated anhydrides or acids, whereby the polarity of the base polymer can be increased. EP266994A2 describes more specifically and in greater detail the process of EVA graftization with polar monomers.

Patent document CN102002182A claims the formulation of an expanded EVA for sports shoe midsole which has high adhesive strength. The formulation contemplates different grades of EVA polymers, ethylene octene copolymer and a maleic anhydride graft polymer in its composition. The bonding strength against rubber is greater than 30 N / cm, however, it is not described which bonding process is used in this patent.

In turn, patent documents KR2010072965A and KR1078354B1 describe the preparation of expanded EVA midsoles further using ethylene-acrylic copolymers or acrylic-derived graphitized copolymers which, when subjected to plasma processing, result in improved adhesion strength to the other components. used in footwear. However, it is known that the plasma process has a high energy consumption when compared to the conventional process by UV radiation, and may result in gluing imperfections, as the soles and / or midsoles may have surfaces that are not exposed to treatment due to the design of the increasingly anatomical part.

Patent document KR 1165803 describes the preparation of acrylic rubber EVA midsole, further utilizing in the formulation an adhesion promoting agent based on modification of inorganic fillers, allowing bonding of the material without the use of UV radiation. However, this document does not describe the amount of bond strength achieved when compared to the conventional bonding system. The inter- The developed EVA base has density and hardness properties outside the requirements needed for its application in sports shoes. Thus, the document does not identify the industrial application of the system.

In turn, patent document KR1104252 has the same purpose as document KR1165803, however, in its composition uses poly (lactic acid) as adhesion promoting agent and a primer, presenting deficiencies in performance-related information after aging tests. (temperature and hydrolysis).

Patent document KR2004046685 describes the preparation of shoe molded EVA which does not require the use of UV radiation in the bonding process. In the method proposed by the technique in question, an expanded EVA component is prepared and a thermosetting adhesive is applied thereto. Subsequently, the part is inserted into a mold where pressure is applied and thermoforming is performed. Particularly, the thermoformable adhesive is obtained by the addition of organic solvent and a modified EVA resin solution and a curing agent. Thus, the EVA piece is ready for bonding to other substrates without the use of UV radiation. The bonding is performed by applying a primer and subsequent application of the PU adhesive. Said document differs from the present invention in that it does not require thermoforming step (which is an additional process step), being possible the direct application of the first expanded EVA component and subsequent application of the adhesive.

In turn, patent document KR561652 discloses an adhesion method in which a PU is used as a polarity modifying agent in the midsole composition to increase the resistance of aggression. However, the use of PU in said composition compromises the component (piece) with respect to hydrolysis resistance, reducing the durability of the shoe.

Based on the state-of-the-art survey, it can be observed that the search for bonding solutions for expanded EVA substrates is constant, and so far no solution has been revealed. indeed replace the UV-bonding process safely and with competitive advantages.

Obtaining a modified ethylene-based copolymer, for example, is widely discussed in the state of the art. However, the use of this type of resin in the footwear industry for obtaining footwear components (such as midsole and / or sole) is unprecedented. In addition, it is also innovative to use a modified ethylene-based copolymer in the composition of a primer for bonding footwear components to other substrates without the need for UV primer activation or part roughing, thus ensuring performance. suitable for industrial application as presented hereinafter.

Thus, the present invention differs from the other solutions found in that it is a solution which has a simplified, economical and sustainable process, ensuring a high level of adhesion quality.

Among the advantages attributed to the technology disclosed in the present patent application is the elimination of the need for the use of UV radiation generating equipment and also the elimination of solid waste generated by the sanding of the shoe component when this process becomes necessary.

OBJECTIVES OF THE INVENTION

The present invention aims to provide a sizing process primer composition comprising at least one modified copolymer. More specifically, the composition of the present invention comprises a polar monomer-modified ethylene-vinyl acetate copolymer.

It is also an object of the present invention to provide a process of bonding an expanded EVA component to a substrate comprising the following steps:

a) obtain an expanded EVA component;

b) clean the surface of the expanded EVA component; c) applying the primer composition to the surface of the expanded EVA component;

d) applying an adhesive to the surface of the expanded EVA component;

e) heating the expanded EVA component adhered to the adhesive;

f) pressing the expanded EVA piece adhered to the adhesive;

Further, the present invention aims to provide an expanded EVA component comprising melt index between 0.1 and 50 g / 10 minutes and 10 to 60% (w / w) vinyl acetate, and 0 to 90% of modified copolymer.

Additionally the present invention aims to use the primer composition together with the expanded EVA component, both disclosed herein, for bonding shoe parts.

Finally, the present invention is directed to a product comprising the primer composition and expanded EVA component disclosed in the present patent application.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a process of bonding an expanded EVA component to various substrates such as rubbers, polyvinyl chloride (PVC), leathers, PU, thermoplastic elastomers, synthetic components, among others. More specifically, the present invention describes the use of a primer comprising modified copolymer in its composition for use in an expanded EVA component bonding process.

The primer of the present invention comprises one or more modified copolymers dissolved in organic solvents. This primer is applied to the surface of the expanded EVA component, forming a film after solvent evaporation. This film has polarity similar to the polarity of the PU adhesives used in the footwear industry, allowing the bonding of this modified copolymer to other substrates of other footwear components. In a preferred embodiment, at least one modified copolymer is used in the production of the expanded EVA component, resulting in a material having greater polarity compared to the polarity of PU adhesives, which in turn are commonly used. in the footwear industry in bonding components.

Accordingly, the use of an expanded EVA component, preferably comprising the modified copolymer of the present invention, and surface preparation of this expanded material with a modified primer, enables the direct use of adhesives in bonding them to other substrates without the need for adhesion. conventional prior art preparation step.

In the present invention, the modified copolymer is a polar monomer-modified ethylene copolymer that has a higher polarity character compared to conventional ethylene and vinyl acetate copolymer. In this sense, the increase in polarity can be achieved from known synthetic routes, such as the autoclave copolymerization process, in a tubular reactor or via reactive extrusion in a double screw extruder.

In the polymerization process in an autoclave reactor, the reactor has thick walls, usually surrounded by a cooling jacket, equipped with an agitator internally connected to an external motor. The reaction mixture is stirred in the reactor, the temperature being essentially constant, where monomers, initiators and transfer agents may be added at different reaction steps.

In the polymerization process in tubular reactor, the reactor consists of tubes with cooling jacket for temperature control. The diameter of each tube typically ranges from 25 to 64 mm, and the length to diameter ratio can be as high as 40,000, depending on the diameter, copolymerization recipe and desired yield. Tubular reactors are generally separated into successive functional zones, where initiation, cooling, and the copolymerization zone can be divided into several subzones. Temperatures in the zones are maintained regardless pending, and initiators and monomers may be added at various points. The reaction mixture is cooled and discharged from the reactor to separate from unreacted monomers.

In the reactive extrusion process, the ethylene vinyl acetate copolymer is modified in its molten state with polar monomers in the presence of peroxides, which method can be verified in US3904571. The amount of polar monomer used in the invention cited ranges from 0.2 to 30% polar monomer insertion by mass compared to the mass of ethylene and vinyl acetate monomers, more specifically from 0.3 to 10% polar monomer. .

In the present invention, polar monomers are any and all substances having double terminal bonding and electronegative atoms such as oxygen, nitrogen and fluorine in their composition. Examples include: maleic anhydride, itaconic anhydride, citaconic anhydride, alphaamethyl glutaconic anhydride; carboxylic acid esters such as acrylate, methacrylates, 2-methylene glutarates, methylenesuccinates and phthalates; the acrylates and methacrylates being able to include esters of mono or polyhydroxy alcohols such as alkoxy monoalcohols, glycols, triols and tetraols, acrylic or methacrylic acid, fumaric acid, 2-propene 1,2-dicarboxylic acid, maleic acid, undecenoic acid or any other unsaturated carboxylic acids. Other esters include methoxy polyethylene glycol acrylates, ethoxy polyethylene glycol acrylates, ethylene glycol diacrylate, ethylene glycol dimethacrylate, polypropylene glycol diacrylate, polypropylene glycol dimethacrylate, 1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethylacetate diacrylate, neopentyl glycol dimethacrylate, trimethylol ethane triacrylate, trimethylol ethane trimethacrylate, trimethylol propane triacrylate, trimethylol propane trimethacrylate and tetramethylol methane tetracrylate. Among the esters listed, methacrylates are preferred because they have a lower odor and are also less harmful. Methylenosuccinates include, for example, all esters with alkyl or hydrogen bonded groups. Of the 2-methylene glutarates of the esters mentioned, esters with alkyl or hydrogen bonded groups, more preferably methylene-2-dimethyl glutarate, methylene ηο-2-diethyl glutarate, methylene-2-dibutyl glutarate, methylene-2-diallyl glutarate, methylene-2-monomethyl glutarate and methylene-2-monoethyl glutarate. For the addition of the modified copolymer, organic and / or inorganic additives may be used as absorbent agents for polar substances such as silica, molecular sieves, talc, zeolite, among others, with or without modification.

In view of the importance of primer in the shoe bonding process, the inventors of the present patent application have studied the modification of the ethylene vinyl acetate copolymer with other components, achieving a different bonding strength compared to conventional processes. . In other words, it was observed that the addition of modified copolymers in a primer favors excellent adhesion and cohesion between the expanded EVA component and substrates, thus eliminating the need for the primer cure (activation) step through radiation. with UV light.

In a preferred embodiment, the preparation of the primer composition consists of dissolving one or more modified copolymers in organic solvents, adding adhesion promoting additives, synthetic polymers, inorganic acids, among others. In addition, the primer composition has an amount of dissolved solid materials of 0.5% to 15%; more preferably from 1% to 10%.

The modified copolymers used in the primer may be one or more of which the disclosure is described in the present invention, used in a weight ratio of 0.05 to 15%, more preferably from 1% to 8%, based on the total mass of the primer. The solvents used in the present invention are mixtures of ketones, organic esters, glycol esters, and other organic solvents such as propanone, butanone, methyl isobutyl ketone, diisobutyl ketone, ethyl acetate, methyl acetate, butyl acetate, tert-butyl, isoamyl acetate, 2-ethylhexyl acetate, cyclohexyl acetate, methoxypropyl acetate, butylglycol, ethylglycol, n-hexane, cyclohexane, methylcyclohexane, methylcyclopentane, cyclohexanone, alpha and beta pyenes, limonene, bisabolene and zingiberene, methyl benzene, compounds of dimethyl benzene may have ortho, meta and para structural molecular configuration at a ratio of 75 to 99.95% more preferably 90 to 99.5%. For complete dissolution of the components, heating of the mixture may be necessary depending on the combination of the components used.

Adhesion promoters may be selected from chlorine-containing rubber copolymers in their chemical structure, such as polychloroprene, chlorobutyl rubber, chlorosulfonated polyethylene, PVC, chlorinated polyolefin, vinylidene polychloride and mixtures thereof in proportion. 1 to 10% by weight, more preferably 0.05 to 5%.

In addition, the primer composition may contain inorganic and organic acids such as: phosphorous, hypophosphorous, diphosphoric, tripolyphosphoric and phosphoric acid, butanedioic acid, butenedioic acid, propanedioic acid and 1,6-hexanedioic acid in parenchymal mixtures. 1 to 10%, more preferably 0.05 to 5%.

In the present invention, the expanded EVA component of the footwear (sole and / or midsole) has in its formulation a conventional EVA resin having a melt index between 0, 1 and 50 g / 10 minutes and from 10 to 60% (m / m) of vinyl acetate, and from 0 to 90% modified copolymer, preferably from 1 to 80%, based on the total mass of the expanded EVA component. The formulation may also comprise other common and / or inherent additives to the EVA expansion process, such as blowing agents comprising azodicarbonamide, inorganic fillers, expansion activators, organic peroxides, plasticizers, thermoplastic resins, elastomers, pigments and crosslinked EVA. recycled (shavings).

For the preparation of the expanded EVA component of the present invention, expanded EVA is used as per conventional expansion process. Initially, all components are weighed on an analytical balance and mixed in an open or internal roller mixer at a temperature of 90 to 120 ° C, sufficient to plasticize the polymeric materials and mix them with the components. more components (additives). After the mixing step, the formulation is cooled and kept at room temperature for further crosslinking and expansion as described in the literature.

Once the expanded EVA component (sole and / or midsole) is finished, its surface should be cleaned with organic solvents, water (pure or detergent), or other solutions for the removal of mold release and impurities, which may interfere with the process of adhesion and penetration of the primer on the workpiece surface. In this step, the organic solvents may be ketones, organic esters, glycol esters, and other organic solvents such as propanone, butanone, methyl isobutyl ketone, diisobutyl ketone, ethyl acetate, methyl acetate, butyl acetate, acetate tert-butyl acetate, isoamyl acetate, 2-ethylhexyl acetate, cyclohexyl acetate, methoxypropyl acetate, butylglycol, ethylglycol, n-hexane, cyclohexane, methylcyclopentane, cyclohexanone, alpha and beta pinenos, limonene, bisabolene, z methyl benzene, dimethyl benzene compounds which may have ortho, meta and para structural molecular configuration, more preferably propanone, butanone or mixtures thereof.

After cleaning the expanded EVA component, the primer is applied to the surface of the expanded EVA component via the complete immersion process of the part or by applying it via brush. Complete evaporation of solvents depends on the solvents chosen, and the appropriate evaporation time may vary from 2 to 30 minutes, depending on ambient temperature and relative humidity, more specifically from 5 to 20 min. Subsequently, on the surface of the workpiece is applied PU-based adhesive which may be in solid (powder or granule) or liquid form, and when in liquid form the adhesive is dissolved in organic solvents or dispersed in aqueous medium.

After applying the adhesive, the volatiles should be allowed to evaporate completely if solvent or water is present. Evaporation time may vary from 3 to 30 minutes. Also, in the case of PUs dissolved in solvents, their quantity must be 5 to 25% by mass of total composition of the adhesive, more preferably from 12 to 19%. In the case of PU dispersed in water, its amount should range from 35% to 65% by mass of the total adhesive composition, more preferably from 40 to 55%. On the other hand, for the preparation of the final footwear, a surface treatment of the leather / sole should be performed before its bonding in the EVA sole and / or midsole (expanded EVA component), and this treatment will depend on the composition of the shoe. leather and sole, but specifically cleaning them with organic solvent or water (pure or detergent).

After complete evaporation of volatiles, if present, the expanded EVA component (sole and / or midsole) should be heated by hot air flow, infrared radiation or heat radiation lamp, reaching a temperature between 55 and 70 ° C. ° C according to the melting point of the PU used in the adhesive composition. After fusion, the pieces (sole and / or midsole and leather) are joined and brought to a press. Then the pieces are properly bonded. The bonding strength of materials is greater than or equal to 30 N / cm, maintained after heat treatment and hydrolysis, and reaches its maximum after 72 hours, the average time required for complete crystallization of the PU adhesive at room temperature after melting. The methodology used to assess adhesion strength is described in ASTM D-1876, Standard Test Method for Pee Resistance of Adhesives (T-Peel Test).

The bond strength varies according to the formulation of the expanded EVA component. It can be mentioned as factors of influence, the size of the gas cells that promotes the expansion of this EVA. The larger the size of this cell, the greater the porosity of the expanded EVA, and hence the lower the density of this material, and the greater its degree of expansion. The higher the porosity of the material, the greater the possibility of penetration of the solid base polymer chains dissolved in organic primer solvents, allowing greater interaction with the material, resulting in higher bond strength results. Another important factor is the cohesion of the formulation of the VAS component ex- pandido. If the formulation has low cohesion, the bond strength is limited to the value of the internal cohesive forces of the expanded EVA material, and thus the material is torn, and the bonding interface is not affected. In cases where material cohesion is high, the bond strength increases substantially, however, there is no disruption of the expanded EVA cohesive structure.

For a better understanding of the present invention and the improvements obtained, the following are some embodiments which should not be construed as limiting the scope and scope of the invention.

To allow a better understanding of the present invention and to clearly demonstrate the technical advances obtained, the results of Examples 1 to 3, comprising compositions formulated within what is described and claimed herein, and a comparative example using the traditional sizing process used in the present invention are now presented. footwear industry.

EXAMPLES

The expanded EVA primer for various substrates was prepared by the addition of 80% acetone, 10% ethyl acetate and 5% modified copolymer containing 26% vinyl acetate, 67% ethylene and 7% acid 2. 1,2-Dicarboxylic propylene, with subsequent heating and stirring for complete dissolution of the solid components.

In preparing the compositions illustrating the present invention, the following polymeric materials were used for the composition of an expanded EVA midsole for sports shoes:

· Engage 8200: elastomeric polyolefin (ethylene octene copolymer), melt index 5 g / 10 min (2.16 kg / 190 ° C, ASTM D1238).

• EVA 3019PE: EVA with 19% (w / w) acetate content and melt index 2.5 g / 10 min (2.16 kg / 190 ° C, ASTM D1238).

• HM 728: EVA with 28% w / w acetate and 6 g / 10 min melt index (2.16 kg / 190 ° C, ASTM D1238).

• Modified copolymer used in expanded EVA: copolymer with 80.5% ethylene 19.0% vinyl acetate and 0.5% acid 2- 1,2-Dicarboxylic propene, with melt index 2.5 g / 10 min (2.16 Kg / 190 ° C, ASTM D1238).

Table 1 shows the amounts in parts of input per 100 parts of resin (phr) of each material in the example formulations. Examples include compositions formulated from some qualitative and quantitative variations of the different components involved within what is described and claimed herein.

Table 1 - Expanded EVA midsole component compositions.

The expanded EVA was prepared according to the sequential addition of the cooled and granulated mixing roll components at 85 ° C in a single screw extruder. The samples obtained in the form of granules were then added to the 10 mm thick plate mold press, and then pressed at 175 ° C for 10 minutes, yielding the expanded midsole EVA component of a footwear. sportive.

The expanded midsole EVA component of sports shoes was cleaned with a mixture of acetone and ethyl acetate, and then the primer was applied. After 10 minutes of drying the primer solvent, the aliphatic polyurethane adhesive dissolved in acetone with 3% crosslinking agent (polyisocyanate dissolved in ethyl acetate) was applied. on the surface of the midsole. The rubber sole was sanded, prepared with trichloroisocyanuric acid primer dissolved in ethyl acetate. Drying was performed for 20 minutes and then the aliphatic polyurethane adhesive dissolved in acetone with 3% crosslinking agent (polyisocyanate dissolved in ethyl acetate) was applied. After 15 minutes, the solvent evaporated from the adhesives. The midsole and rubber sole were brought to a hot air circulating furnace in the range of 60 to 65 ° C, the polyurethane melting and then the midsole and the sole being joined for bonding. The pieces were pressed at 80 Ibf / in ² for 15 seconds to increase contact between the pieces and ensure greater bonding efficiency.

Table 2 shows the hardness of the expanded EVA component (midsole) and the bonding strength of this component to the rubber substrate (sole). In this Table it can be seen that the results of the new technology developed in the present invention is comparable to the traditional technology used by the footwear segment (Comparative Example).

In addition, another requirement that was met with the new proposal was no delamination at the interface, as there is a delamination of the material, rubber (substrate). In other words, there was a rupture of the substrate, thus indicating that there is excellent adhesion and cohesion between the EVA piece and the substrate, according to the technical requirements of the footwear segment. This behavior is due to the higher number of thermolecular forces between the EVA chains of the expanded EVA component (EVA base and modified copolymer), primer (modified copolymer base) and PU base adhesive. Therefore, the modified copolymer present in both the expanded EVA component formulation and the primer gives a different chemical composition (increase of surface energy) in relation to the traditional chemical composition of an EVA component, being responsible for promoting strong molecular interactions with the EVA component. modified copolymer primer, as well as a greater diffusion thereof within the polymer matrix of the expanded EVA component and thus greater anchorage. Thus, greater security in the gluing process is gained. reducing energy in the production process of a shoe.

It was also verified that after hydrolysis process (50 ° C to 95% humidity for 7 days) and thermal aging (seven days in a greenhouse at 50 ° C) there was no decay of bonding strength between midsole and rubber sole. . Thus, it can be concluded that there was no migration of formulation components to the surface (a fact that could compromise the bonding).

Table 2 - Pasting Properties.

Note: ( ^* ) Bonding strength after subjecting sample to 50 ° C with 95% humidity for 7 days; ( ^** ) Bonding strength after subjecting sample to 50 ° C for 7 days; ( ^{* 1} ) VAS substrate delamination has occurred.

Claims

Priming composition for the sizing process comprising at least one modified copolymer.

Composition according to Claim 1, characterized in that the copolymer is a polar monomer-modified ethylene-vinyl acetate copolymer.

Composition according to Claim 2, characterized in that the monomers are substances having double terminal bonding and electronegative atoms such as oxygen, nitrogen and fluorine in their composition.

Composition according to Claim 3, characterized in that the monomers are selected from the group comprising maleic anhydride, itaconic anhydride, citaconic anhydride, alpha-methyl glutaconic anhydride, carboxylic acid esters, acrylate, methacrylates, 2-methylene glutarates, methylenesuccinates and phthalates;

Composition according to Claim 4, characterized in that the acrylates and methacrylates are selected from the group comprising esters of mono or polyhydroxy alcohols, alkoxy monoalcohols, glycols, triols and tetraols, acrylic or methacrylic acid, fumaric acid , 2-propene 1,2-dicarboxylic acid, maleic acid, undecenoic acid and unsaturated carboxylic acids.

Composition according to Claim 4, characterized in that the esters are selected from the group comprising methoxy polyethylene glycol acrylates, ethoxy polyethylene glycol acrylates, ethylene glycol diacrylate, ethylene glycol dimethacrylate, polypropylene glycol diacrylate, polypropylene glycol dimethacrylate 1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, trimethylol ethane triacrylate, trimethylol ethane trimethacrylate, trimethylol propane triacrylate, trimethylol propane tetramethacrylate

Composition according to any one of the claims

1 to 6, characterized in that the copolymer is modified by autoclave, tubular reactor or extrusion copolymerization process reactive double screw extruder.

Composition according to any one of Claims 1 to 7, characterized in that the copolymer has a mass ratio of 0.05 to 15% based on the total mass of the primer.

Composition according to any one of the claims

1 to 8, characterized in that the copolymer is dissolved in a solvent mass ratio of 75 to 99.95% based on the total mass of the primer.

Composition according to Claim 9, characterized in that the solvents are selected from the group comprising mixtures of ketones, organic esters, glycolic esters, propanone, butane, methyl isobutyl ketone, diisobutyl ketone, ethyl acetate, methyl, butyl acetate, tert-butyl acetate, isoamyl acetate, 2-ethylhexyl acetate, cyclohexyl acetate, methoxypropyl acetate, butylglycol, ethylglycol, n-hexane, cyclohexane, methylcyclohexane, methylcyclopentane, cyclohexa ninth, alpha and beta pinenes, limonene, bisabolene and zingiberene, methyl benzene, dimethyl benzene compounds comprising ortho, meta and para structural molecular configuration.

Composition according to any one of Claims 9 to 11, characterized in that the dissolution of the copolymer in solvent is heated.

Composition according to Claim 1, characterized in that the composition comprises adhesion promoters in the weight ratio of 1 to 10% based on the total mass of the primer.

Composition according to Claim 13, characterized in that the adhesion promoters are selected from the group comprising chlorine-containing rubber copolymers in their chemical structure.

Composition according to Claim 14, characterized in that the copolymers are selected from the group comprising polychloroprene, chlorobutyl rubber, chlorosulfonated polyethylene, PVC, chlorinated polyolefin, vinylidene polychloride and mixtures thereof.

Composition according to Claim 1, characterized in because the composition comprises 1 to 10% inorganic and organic acids based on the total mass of the primer.

Composition according to Claim 15, characterized in that the inorganic and organic acids are selected from the group comprising phosphorous, hypophosphorous, diphosphoric, tripolyphosphoric and phosphoric acid, butanedioic acid, butenedioic acid, propanedioic acid, acid. ethanedioic acid and 1,6 hexanedioic acid in partial or complete mixtures.

Process of bonding an expanded EVA component to a substrate having the primer composition as defined in claims 1 to 16, characterized in that it comprises the following steps:

a) obtain an expanded EVA component;

b) clean the surface of the expanded EVA component;

c) applying the primer composition to the surface of the expanded EVA component;

d) applying an adhesive to the surface of the expanded EVA component;

e) heating the expanded EVA component adhered to the adhesive;

f) pressing the expanded EVA piece adhered to the adhesive;

Process according to Claim 17, characterized in that in step d) the adhesive is in solid or liquid form.

Process according to Claim 21, characterized in that the adhesive in liquid form is dissolved in organic solvents or dispersed in aqueous medium.

Process according to claim 17, characterized in that in step e) the heating occurs by means of hot air flow, infrared radiation or heat radiation lamp.

Process according to Claim 23, characterized in that the heating takes place at a temperature between 55 and 70 ° C.

Process according to Claim 17, characterized in that the bonding strength is greater than or equal to 30N / cm.

Process according to Claim 17, characterized in that the substrate is selected from the group of rubbers, polyvinyl chloride, leather, PU, thermoplastic elastomers and synthetic components.

Expanded EVA component used in the process as defined in claims 17 to 23, characterized in that it comprises a melt index between 0.1 and 50 g / 10 minutes and 10 to 60% (w / w) acetate vinyl, and from 0 to 90% modified copolymer

Component according to claim 24, characterized in that it comprises blowing agents, azodicarbonamide, inorganic fillers, blowing activators, organic peroxides, plasticizers, thermoplastic resins, elastomers, pigments and recycled cross-linked EVA.

Use of the primer composition as defined in claims 1 to 16 together with the expanded EVA component as defined in claims 24 and 25, characterized in that it is for bonding shoe parts.

Product comprising the primer composition as defined in claims 1 to 16 and the expanded EVA component as defined in claims 24 and 25.

Invention, characterized by any of its embodiments or claim categories encompassed by the subject matter initially disclosed in the patent application or examples herein.