WO2018128557A1

WO2018128557A1 - Method for producing and applying hot-melt adhesives

Info

Publication number: WO2018128557A1
Application number: PCT/PT2018/050001
Authority: WO
Inventors: Denise Neves GAMEIRO
Original assignee: Gameiro Denise Neves
Priority date: 2017-01-06
Filing date: 2018-01-05
Publication date: 2018-07-12
Also published as: PT109838A

Abstract

The present invention relates to a method for producing and applying hot-melt adhesives, comprising the following steps: adding at least one polymer and one adhesion agent to a homogenizer/melter; mixing and heating the at least one polymer and one adhesion agent to a temperature above the melting point of the mixture to obtain a melted glue; transferring the melted glue to a melted-glue application mechanism; and applying the melted glue. The present invention also relates to the use of the method for producing and applying the melted glue in systems used for packaging, labelling, producing nappies, self-adhesive labels, laminating and the like.

Description

DESCRIPTION

PRODUCTION AND APPLICATION PROCESS OF TERMOFUSIVE IS ADHESIVES

FIELD OF INVENTION

The present invention relates to a process of producing and applying hot melt adhesives. This process can be applied in packaging systems, labeling, diaper production, self-adhesive labels, laminating, among others.

BACKGROUND OF THE INVENTION

The use of hot melt adhesives in the processes of wrapping, packaging, labeling and diaper production, lamination and others is well known.

Currently the method for producing hot melt adhesives comprises essentially two steps: a) melting and mixing all formulation ingredients in a mixer (equipped with heating, stirring and inert gas purge); (b) discharge of the homogenised mass produced in (a), followed by its cooling / shaping and packaging.

The type of cooling and packaging varies depending on the type of hot melt adhesive. Generally speaking, the most common hot melt adhesives are packing adhesives and pressure sensitive adhesives. In the case of packaging adhesives, these are usually cooled in the form of strips on stainless steel screens, cooled on the opposite side by water jets, the strips being cut into small portions after they have solidified and on leaving the screen, using for this purpose a cutter. Thus, small "mosaics" of hot melt glue are obtained. Another process involves producing these glues in the form of pearls (small balls) using a rotoformer and projecting the pearls into water where they are cooled, then collected, dried and packaged. In the case of pressure sensitive adhesives, the cooling screen may not be used and other methods such as pouring onto small silicon paper cubes or forming small pillows by casting onto film sleeves must be used. appropriate plastic and cooling under water, followed by cutting into small portions.

The above mixer may be replaced by an extruder, where the material is pressurized while frictionally heating and / or heat is supplied from the outside.

The material obtained by processes known in the prior art has as its main feature a homogeneous appearance.

Upon application, the material is introduced into a heated container, known as an oven, so as to melt and be applied. Known and currently used processes are time consuming and energy-intensive as they require repetition / addition of steps (melting, cooling, packaging). In addition, the properties and quality of the material obtained are partly affected by said additional steps.

Thus, there is a need in the art for a process of producing and applying hot melt adhesives that minimizes and simplifies the steps leading to obtaining the final material without changing its properties and performance.

Surprisingly, it has been found, after extensive research and experimentation, that the process of the present invention enables the necessary steps to be reduced, energy costs reduced and properties and performance ensured by the following process.

SUMMARY OF THE INVENTION

The present invention provides a process for the production and application of hot melt adhesives consisting of the steps of: a) adding at least one polymer and an adhesive to a homogenizer / melter; b) mixing and heating the at least one polymer and an adhesive to a temperature above the melt temperature of the mixture to obtain a molten glue; c) transferring the melt glue from step b) to a melt glue application mechanism; and d) apply the molten glue.

Preferably, the polymer is selected from an ethylene vinyl acetate copolymer (EVA), a styrene isoprene copolymer (SIS) and ethylene homopolymer produced by the metallocene catalyst.

Preferably, the tackifier is selected from rosin ester resins, C5, C9 hybrid, terpene or terpene-phenolic hydrocarbon resins.

In a preferred embodiment, the polymer and adhesive in step a) are, respectively, an EVA polymer and a rosin ester resin.

In another embodiment, in step a), components selected from the group comprising waxes, pigments, fillers, plasticizers and antioxidants are also added. In yet another embodiment, the waxes are selected from microcrystalline wax and Fisher-Tropsch wax, the pigments are titanium dioxide or titanium dioxide based, fillers are selected from the group comprising calcium carbonate, talc, magnesium hydroxide , natural and synthetic fibers, plasticizers are mineral oils obtained from petroleum products and antioxidants are pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate) (Irganox 1010), 3, Benzenopropionic acid 5-bis (1,1-dimethylethyl) -4-hydroxyoctadecylester or Î ±, Î ± -1,6-hexanidylbis (3,5-bis (1,1-dimethylethyl) -4-hydroxy) benzenopropanamide. In a preferred embodiment, the adhesive is in the form of a premix.

In a more preferred embodiment, the premix is selected from a premix consisting of a rosin ester, a microcrystalline wax and a Fisher-Tropsch wax and a premix consisting of a hydrocarbon resin and a Fisher-Tropsch.

In one aspect of the invention, the temperature in step b) is in the range 100-250 ° C, preferably 140-200 ° C and even more preferably 150-170 ° C.

In one embodiment, the transfer of glue from the homogenizer / melter to the delivery mechanism is automatic, semi-automatic or manual, in a continuous, semi-continuous or discontinuous manner.

The process of the invention may be used in systems comprising packaging, labeling, diaper production, self-adhesive labels and laminating systems.

DESCRIPTION OF INVENTION

The present invention relates to a process of producing and applying hot melt adhesives.

In the context of the present disclosure, the term "comprising" is to be understood as "including but not limited to". As such, that term should not be construed as "consisting solely of". Note that any X-value presented in the course of the present disclosure should be interpreted as an approximate value of the actual X-value, as such approximation to the actual value would be reasonably expected by one skilled in the art due to experimental and / or measurement conditions that introduce deviations from the actual value.

Unless otherwise indicated, the ranges of values set forth herein are intended to provide a simplified and technically acceptable way to indicate each individual value within its range. By way of example, the term "1 to 2" or "between 1 and 2" means any value within this range, for example 1.0; 1.1; 1,2; 1.3; 1.4; 1.5; 1.6; 1.7; 1.8; 1.9; 2.0. All values mentioned in the present description should be interpreted as approximate values, for example the reference to "160 ° C" means "about 160 ° C". By the present invention is meant "hot melt adhesives" adhesives which are hot applied. These adhesives are solvent free and therefore become fluid when heated, thus allowing their application to be hot and drying quickly by simple cooling to room temperature.

A hot melt glue consists of at least two components, a polymer and an adhesive. Depending on the desired characteristics of the hot melt glue, its formulation may further include additional components such as various types of waxes, pigments, fillers, plasticizers, antioxidants or other additives. The above components are solid at room temperature, except for most plasticizers. The solid materials come in granular, scale or powder form. The plasticizers may be liquid or, for example, pre-encapsulated.

In the context of the present invention, "near the place of application" means any place where it is expedient to supply the melt glue to the glue application equipment.

In the present invention, "fused glue" is meant to be the glue in its melted state. The following describes in detail the process of producing and applying hot melt adhesives of the present invention. The process of the present invention consists of the steps of: a) adding at least one polymer and an adhesive to a homogenizer / melter; b) mixing and heating the at least one polymer and an adhesive to a temperature above the melt temperature of the mixture to obtain a molten glue; c) transferring the melt glue from step b) to a melt glue application mechanism; and d) apply the molten glue. In the process of the present invention, the polymer has the essential and determining function of imparting mechanical strength (cohesion) to the glue. The most commonly used polymers may be selected from the group comprising: an ethylene vinyl acetate copolymer (EVA), a styrene isoprene copolymer (SIS) and ethylene homopolymer produced by the metallocene catalyst. The polymer is chosen according to the characteristics of the desired adhesive and also the other adhesive components to be used. The person skilled in the art, based on the teachings of the invention, may select the appropriate polymer. In the process of the present invention, the adhesive agent is intended to promote adhesion to the substrate. The absence of this compound results in drawbacks in the performance of the adhesive, namely substrate delamination. The tackifier used in the present invention may be selected from the group comprising: rosin ester resins (obtained by esterification of the rosin with glycerin, pentaerythritol and other alcohols or polyols), hydrocarbonic C5, C9 hybrid, terpene or terpene resins - phenolic. The person skilled in the art, based on the teachings of the invention, may select the appropriate adhesive agent.

In one embodiment, the polymer and adhesive in step a) are, respectively, an EVA polymer and a rosin ester resin. The preferred mode depends on the adhesive you wish to use and what functions it is intended for. For example, an Anglo-Saxon Pressure Sensitive Adhesive (PSA) usually does not use an EVA polymer because it does not give it the recognized good characteristics of a PSA.

In one embodiment, in step a) one or more components selected from the group comprising waxes, pigments, fillers, plasticizers and antioxidants are added.

These components, also referred to as additives, perform different functions in the mixture.

Waxes reduce the viscosity of the adhesive in the melt state and promote better contact / adhesion with the substrate by lowering viscosity. Preferably, the wax used is a microcrystalline wax consisting of low molecular weight aliphatic hydrocarbons which are quite branched and form microcrystals.

In most cases Fisher-Tropsch (FT) wax is used together with microcrystalline waxes. This is a synthetic wax with synergistic effect on microcrystalline wax, where the melting point of the mixture is higher than would be expected from the percentages / melting points. The melting point of the mixture moves to the melting point side of the (highest) FT wax. Moreover, the percentage of FT wax is used to control "open time". The higher the percentage of TF, the lower the "open time". "Open time" is defined as the time interval in which the gluing operation can be performed from the time of glue application. Once the open time expires it will no longer be possible to paste because the glue got hard. In general, the faster the "drying" the smaller the "open time". For example on a packaging line, if we want to increase the speed, we have to decrease the "open time" to prevent the boxes from reopening as soon as the machine releases the sticking pressure.

Pigments may also be added according to the desired color, provided they are resistant to the glue preparation and application temperature. For example, to obtain the white color, titanium dioxide or titanium dioxide based pigments which give a white and opaque color to the glue are used in the present invention.

In step a), charges may also be added to lower the cost and obtain a stiffer glue.

Preferably, the fillers are selected from the group comprising calcium carbonate, talc, magnesium hydroxide, natural and synthetic fibers.

Plasticizers are additives whose function is to increase the flexibility of mixtures, since they have high compatibility with polymers and can, by the molecular bonds they establish, increase the distance between molecules. Thus, the addition of plasticizers in step a), by making the glue more flexible, allows adhesion to the substrate at a lower temperature.

In one embodiment, the plasticizers used are mineral oils obtained from petroleum products. Antioxidants are a class of additives designed to inhibit the oxidation of other molecules, in this particular case protecting the glue from thermal oxidation as it is subjected to high temperature during application.

Preferably, a phenolic type antioxidant powder is used, for example pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate) (Irganox 1010), 3,5 - benzenopropionic acid bis (1,1-dimethylethyl) -4-hydroxy octadecylester or N, N '-1,6-hexanidylbis (3,5-bis (1,1-dimethylethyl) -4-hydroxy) benzenopropanamide.

In yet another embodiment of the present invention, the adhesive may be a premix consisting of a rosin ester, a microcrystalline wax and a Fisher-Tropsch wax or a premix consisting of a C5 hydrocarbon resin and a wax. Fisher-Tropsch The premixes can be in the form of scales, pearls (small grains), among others.

The use of these premixes may be advantageous since waxes are already included when the glue preparation begins. The ratio of the various components can be adjusted by the skilled person according to the hot melt glue to be obtained.

Addition of the components in step a) can be done in several ways: addition of each component by means of a dispenser, for example by withdrawing the required amounts from a bulk bag using a dosing cup; addition of components packed in one or more inclusive packages; adding packaged components in one or more non-inclusive packaging after opening the package.

Within the scope of the present invention, the term "inclusive package" means that the package in which one or more components have been packed is comprised of polymeric material which is consumed in step b), which allows the package containing the components to be packaged. added to the homogenizer / smelter, avoiding opening the package, with the consequent possible waste and waste production.

In the scope of the present invention, the term "non-inclusive packaging" means that this packaging has to be opened for addition of the components to the homogenizer / melter and the discarded packaging.

The components may be added to the homogenizer / melter as available on the market one by one or some of them premixed and / or pre-homogenized or all / some prepackaged in inclusive or non-inclusive packaging. Any combination mentioned above is possible, provided it has at least two inhomogeneous ingredients, for example a polymer and an adhesive, or a polymer and an adhesive pre-homogenized with a wax, or a polymer and a pre-dispersed pigment. in an adhesive, or a polymer an adhesive and an encapsulated plasticizer.

The homogenizer / melter must have a heating and mixing / homogenizing function so that the components melt at the desired temperature and form a homogeneous melt glue.

The function of the homogenizer / melter is to produce hot melt adhesives near the adhesive application site and deliver them still fused to the application mechanism.

The homogenizer / melter can be any equipment or set of equipment capable of processing any hot melt adhesive formulation.

The homogenizer / melter can be any piece of equipment or set of equipment that carries out melting (heating) and melt homogenization processes.

Continuous or semi-continuous operating homogenizer / melter.

The homogenizer / melter can operate completely automatically, semi-automatically or manually.

The ingredients can be fed to the homogenizer / melter automatically, semi-automatically or manually, continuously, semi-continuously or discontinuously.

In the present invention, and generally, the temperature in step b) is in the range 100-250 ° C, preferably 140-200 ° C and even more preferably 150-170 ° C. .

Delivery of the melt glue from the homogenizer / melter to the delivery mechanism can be accomplished by means of heated tubing or otherwise such as in containers suitable for handling melt adhesives.

In a preferred embodiment, delivery of the molten glue is made discontinuously.

Synchronization of homogenizer / melter glue delivery to the delivery mechanism may be automatic, semi-automatic or manual, in a continuous, semi-continuous or discontinuous manner.

Application of the molten glue may be by any application mechanism known to the person skilled in the art.

This process allows the melting of the components to occur only near the place of glue application, preserving the properties of the material obtained by avoiding the repetition of melting, packaging and cutting steps. The number of process steps is thus reduced as it eliminates the initial melting step as well as the packaging and cutting of the material.

Thus, the process of the invention proves to be an excellent improvement over the processes known and used in the art, for its simplicity of execution and for minimizing the necessary steps for its execution, as well as for energy saving. EXAMPLES

Example 1

To a homogenizer / melter was added 50% EVA polymer and 50% rosin ester resin.

The above components were heated and homogenized at a temperature of 170 ° C.

The melt glue was transferred to the melt glue application mechanism and used for packaging.

Example 2

47% EVA polymer, 52% of a premix of rosin ester, microcrystalline wax and Fisher-Tropsch wax and 1% Irganox 1010 previously packaged in an inclusive package were added to a homogenizer / melter.

It was heated and homogenized at a temperature of 170 ° C.

Example 3

To a homogenizer / melter were added 47% EVA polymer, 46% rosin ester resin, 3% microcrystalline wax, 3% Fisher-Tropsch wax and 1% Irganox 1010, previously packaged in a non-inclusive package.

It was heated and homogenized at a temperature of 170 ° C.

Example 4

46% EVA polymer, 43% rosin ester resin, 3% microcrystalline wax, 3% Fisher-Tropsch wax, 4% pre-dispersed rosin ester titanium dioxide were added to a homogenizer / melter. (as scales) and 1% Ν, Ν '-1,6-hexanidylbis (3,5-bis (1,1-dimethylethyl) -4-hydroxy) benzenopropanamide, previously packaged in a non-inclusive package.

It was heated and homogenized at a temperature of 180 ° C.

The melt glue was transferred to the melt glue application mechanism and applied to laminates.

Example 5

46% SIS polymer, 46% C5 hydrocarbon resin, 7% plasticizer Encapsulated mineral oil and 1% Irganox 1010, previously packaged in a non-inclusive package, were added to a homogenizer / melter. It was heated and homogenized at a temperature of 160 ° C.

The melt glue was transferred to the melt glue mechanism and applied to diaper production.

Example 6

39% PE-metallocene polymer, 29% C5 hydrocarbon resin, 30% Fisher-Tropsch wax and 2% N, N '-1,6-hexanidylbis (3,5-bis) were added to a homogenizer / melter. (1,1-dimethylethyl) -4-hydroxy) benzenopropanamide, previously packaged in a non-inclusive package.

It was heated and homogenized at a temperature of 200 ° C.

The melt glue was transferred to the melt glue application mechanism and applied in packaging.

Example 7

To a homogenizer / melter were added 39% PE-metallocene polymer, 59% from a premix consisting of C5 hydrocarbon resin and Fisher-Tropsch wax and 2% Irganox 1010.

It was heated and homogenized at a temperature of 200 ° C.

Claims

REINDICATIONS

Process for the production and application of hot melt adhesives characterized by the steps of: (a) adding at least one polymer and an adhesive to a homogenizer / melter; b) mixing and heating the at least one polymer and an adhesive to a temperature above the melt temperature of the mixture to obtain a molten glue; c) transferring the melt glue from step b) to a melt glue application mechanism; and d) applying the molten glue.

Process according to Claim 1, characterized in that the polymer is selected from an ethylene vinyl acetate copolymer (EVA), a styrene and isoprene copolymer (SIS) and an ethylene homopolymer produced by the metallocene catalyst.

Process according to Claim 1, characterized in that the adhesive is selected from rosin ester resins, hydrocarbonic C5, C9 hybrid, terpene or terpene-phenolic resins.

Process according to any one of claims 1 to 3, characterized in that the polymer and the adhesive are not step a) are, respectively, an EVA polymer and a rosin ester resin.

Process according to claim 1, characterized in that in step a) components selected from the group comprising waxes, pigments, fillers, plasticizers and antioxidants are also added.

Process according to Claim 5, characterized in that the waxes are selected from microcrystalline wax and Fisher-Tropsch wax.

Process according to Claim 5, characterized in that the pigments are titanium dioxide or based on titanium dioxide.

Process according to Claim 5, characterized in that the fillers are selected from the group comprising calcium carbonate, talc, magnesium hydroxide, natural and synthetic fibers.

Process according to Claim 5, characterized in that the plasticizers are mineral oils obtained from petroleum products.

Process according to Claim 5, characterized in that the antioxidants are pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate) (Irganox 1010), 3,5-bis (1,1-1 benzenopropionic acid dimethylethyl) -4-hydroxyoctadecylester or N, N '-1,6-hexanidylbis (3,5-bis (1,1-dimethylethyl) -4-hydroxy) benzenopropanamide.

Process according to Claim 1, characterized in that the adhesive is in the form of a premix.

Process according to Claim 11, characterized in that the premix is selected from a premix consisting of a rosin ester, a microcrystalline wax and a Fisher-Tropsch wax and a premix consisting of a resin. hydrocarbon and a Fisher-Tropsch wax.

Process according to Claim 1, characterized in that the temperature in step b) is in the range 100-250 ° C, preferably 140-200 ° C and even more preferably 150-170 ° C. ° C.

Process according to Claim 1, characterized in that the adhesive transfer from the homogenizer / melter to the application mechanism is automatic, semi-automatic or manual, in a continuous, semi-continuous or discontinuous manner.

Use of the process according to Claims 1 to 14, characterized in that it is applied in systems comprising packaging, labeling, diaper production, self-adhesive labels and laminating systems.