EP1311647A1

EP1311647A1 - Hot-melt glues for making pressure-sensitive adhesives

Info

Publication number: EP1311647A1
Application number: EP01960859A
Authority: EP
Inventors: Roland Givord; Eric Rozier; Fabienne Sweeting
Original assignee: "national Starch & Chemical Sa" SA
Current assignee: "national Starch & Chemical Sa" SA
Priority date: 2000-08-01
Filing date: 2001-08-01
Publication date: 2003-05-21
Also published as: FR2812650B1; WO2002010310A1; AU2001282255A1; FR2812650A1

Abstract

The invention concerns hot-melt glues for making pressure-sensitive adhesives, based on thermoplastic rubber, comprising 5 to 40 wt. % of thermoplastic rubber, 20 to 80 wt. % of so-called tacky resin, 0 to 30 wt. % of aromatic resin, 0.05 to 3 wt. % of plasticizing agent. The invention is characterised in that the glues have a content of 1 to 15 % of EPM or EPDM polymer.

Description

HOT MELT ADHESIVES FOR THE MANUFACTURE OF ADHESIVES

PRESSURE SENSITIVE

The present invention relates to the field of pressure-sensitive adhesives and more particularly to the field of pressure-sensitive adhesives without solvent, hot-melt known as "hot-melt".

These hot-melt adhesives are characterized by a sticky residue at room temperature and are intended for coating substrates, for example for the production of labels or adhesive tapes, of various kinds such as plasticized materials, textiles, foams or paper. The formulation of pressure-sensitive adhesives intended to be used by solubilization in solvent phase then drying after coating is well known and described see D. Satas, Handbook of Pressure Sensitive Adhesive Technology (Van Nostrand, NY (1989), but the Problems with energy consumption and ecology have made these implementation techniques less interesting.

The formulation of pressure-sensitive adhesives intended to be used by so-called solvent-free "hot-melt" techniques based on thermoplastic rubbers or ethylene-vinyl acetate copolymers is based on the mixture, in proportions varying according to the qualities desired adhesives and processing difficulties, from 5 to 40% by weight of thermoplastic rubber, from 20 to 80% by weight of so-called tackifying resin, from 0 to 30% by weight of aromatic resin and from 0.05 to 30 % by weight of plasticizer, to obtain an adhesive which will be coated by thermofusion on variable supports and will have a residual adhesive at room temperature.

In the present text, the proportions of the various constituents in the formulations are given unless otherwise indicated in percentage by weight relative to the total weight of the formulation.

By "thermoplastic rubber" is meant, for example, the copolymers comprising vinyl aromatic monomers such as styrene or 1, 3 dienes monomers such as butadiene or isoprene or such as ethylene-butylene or ethylene-propylene. say thermoplastic rubbers such as Styrene-lsoprene-Styrene (SIS), Styrene-Butadiene-Styrene (SBS), Styrene-Ethylene-Butylene-Styrene (SEBS) or Styrene (Ethylene-Propylene) Styrene (SEPS, SEEPS). By "tackifying resin" is meant a resin intended to improve the instant adhesive properties of the mixture, these resins are for example modified C5 or C5 type hydrocarbon resins, modified terpene and terpene resins, hydrocarbon resins of dicyclopentadiene type and resins of natural origin such as rosin esters and tail oil esters.

By "aromatic resin" is meant a resin intended to improve the internal cohesion of the mixture, these resins are for example resins derived from styrene, such as resins derived from alpha-methylstyrene.

By "plasticizer" is meant an additive intended to improve the plasticity of the polymers used, these products qualified as plasticizers are most often polymers or oils of low molecular weight see K.F. Heinisch, Dictionary of Rubber, John Wiley & Sons, N.Y, (1974) such as paraffinic, naphthenic or aromatic oils in general or their mixtures, but also liquid rubber.

Additives such as antioxidants O at 5% by weight, for example antioxidants of the phenolic, thioesters or phosphites type or as UV absorbers. can be added to the mixture as well as fillers such as for example calcium carbonate, Kaolin, calcium sulphate, talc, zinc oxide or glass microspheres.

Dyes or pigments can optionally be added to the adhesive obtained without altering the physico-chemical properties. The supports intended to be coated by hot-melt coating techniques are supports such as, for example, plastic supports in the form of film or plates, fibrous supports, foams or paper supports.

When these supports are plastic supports, they are likely to have been plasticized and therefore to contain plasticizers or plasticizing substances.

These plasticizing substances with respect to the constituents of the supports are also potential plasticizers of the glue previously coated on said support. As previously explained, the formulation of pressure-sensitive adhesives based on thermoplastic rubbers intended for to be implemented by so-called “hot-melt” techniques without solvent has led to resorting to improving the plasticity of these polymers with the use of products qualified as plasticizers.

These plasticizing substances with respect to the constituents of the adhesive are also potential plasticizers of the support previously coated with said adhesive.

These plasticizers which facilitate the implementation of thermoplastic rubbers are known to alter the adhesive performance and their content in the adhesives is the result of numerous formulation tests, which make it possible to obtain adhesives having satisfactory characteristics in terms of adhesiveness. while being plastic enough to be implemented without difficulty by hot-melt techniques.

In the same way, the plasticizer content of plastic supports is the result of formulation tests making it possible to obtain a support having particular characteristics and an addition of plasticizer will be likely to degrade it.

On supports such as paper or textile, any addition of plasticizer will cause degradations such as stains, halos, or even a degradation of the physical qualities of the support by swelling or soaking.

Among the defects listed by the manufacturers of pressure-sensitive adhesives, there are defects in the appearance of the substrates such as, for example, stains, halos, whitish deposits, or swelling. For glues, problems of creep, traces to the uprooting and excessive tackiness of the mass are reported.

Difficulties during cutting of the adhesives can also be encountered, resulting in fouling of the cutting tools, loss of material and appearance defects, for example during the manufacture of labels or during cutting for the production of tapes.

These defects can be consequences of migrations of plasticizers which destroy the equilibria of the glue formulations and / or alter the supports.

These migrations will take place as a function of the affinities of the compounds of the formulations with respect to plasticizers and of the compatibility of the compositions with the various plasticizers but also of the capacities of absorption of the supports and of the compatibility of the materials of the supports with the various plasticizers.

These migrations will have two possible effects:

- alteration of the properties of the adhesive mass with softening and a decrease in internal cohesion, and

- alteration of the properties of the support with formation of stains, halos and physical degradation by softening and / or soaking.

Surprisingly, the Applicant has solved this problem of plasticizer migration by the addition of elastomer of the type

Ethylene-Propylene copolymer or Ethylene-Propylene diene Terpolymer,

EPM or EPDM for example as additives in formulations intended for the preparation of hot-melt for hot-melt adhesives.

This addition of elastomer of the EPM or EPDM type from 1 to 15% by weight has enabled it to reduce or even eliminate these phenomena, while not altering the intrinsic properties of the adhesive mass thus modified.

The copolymers of ethylene and of propylene EPM or EPDM are obtained by polymerizing in suitable proportions ethylene, propylene and a diene, terpolymer for example. These copolymers have no characteristic of sticky raw but excellent resistance to aging, heat and they are known to accept large amounts of oil fillers.

These polymers are not used as thermoplastic polymers in conventional pressure-sensitive adhesive formulations, they are used in the composition of various plastic materials such as materials for waterproofing roofs and in sealants or glues.

EP-A-0 050 044 discloses adhesive compositions containing sulfonated EPDMs. These hot-melt adhesive compositions are glues that do not have residual tack and are not used as pressure-sensitive adhesives, moreover this document specifies that EPDMs have poor adhesive properties.

According to document EP-A-0 714 963, compositions for adhesive tapes which comprise at least one EPDM rubber and a tacky additive to improve the adhesiveness are described. These ribbons adhesives are used to joint rubber sheets for waterproofing roofs, these adhesive tapes have, thanks to their composition rich in EPDM, excellent resistance to aging by heat and good weather resistance. These adhesive tapes act as a seal.

These EPDM or EPM have never been used as additives in formulations intended for the manufacture of adhesives for pressure-sensitive adhesives and their compatibility with such formulations has never been verified. An object of the invention is the formulation of hot-melt adhesives, intended for the manufacture of pressure-sensitive adhesives, based on thermoplastic rubbers, characterized by a content of 1 to 15% of EPM or EPDM polymer.

More particularly, an object of the invention is the formulation of hot-melt adhesives, intended for the manufacture of pressure-sensitive adhesives, based on thermoplastic rubbers, comprising from 5 to 40% by weight of thermoplastic rubber, from 20 to 80 % by weight of so-called tackifying resin, from 0 to 30% by weight of aromatic resin, from 0.05 to 30% by weight of plasticizer, characterized by a content of 1 to 15% of EPM or EPDM polymer.

In the adhesive formulations according to the invention, surprisingly these EPDM or EPM meet specifications, which in addition to the possibility of absorbing large quantities of oil, a property known for these products, allows them to be miscible and compatible with the ingredients used in the formulations intended for the manufacture of pressure-sensitive adhesives without degrading their basic properties, to be implemented by the conventional processes used thanks to their suitable viscosity and above all to limit the migration of plasticizers and therefore stabilize the adhesive properties of the masses that contain them. Another object of the invention is the use, in all formulations of pressure-sensitive adhesives, of EPM or EPDM polymers as an additive intended to suppress the migration phenomena of plasticizers and their effects.

Another subject of the invention is the use of polymers of the EPM or EPDM type, as an additive in pressure-sensitive adhesive compositions used by thermofusion, to improve the cutting and / or eliminating the migration phenomena of plasticizers and their effects.

Another object of the invention is the use of polymers of the EPM or EPDM type, as an additive in pressure-sensitive adhesive compositions based on thermoplastic rubber used by thermofusion, to improve cutting and / or eliminate phenomena of plasticizers migration and their effects.

Another subject of the invention is the use of polymers of the EPM or EPDM type, as an additive in pressure-sensitive adhesive compositions based on thermoplastic rubber, comprising from 5 to 40% by weight of thermoplastic rubber, from 20 to 80% by weight of so-called tackifying resin, from 0 to 30% by weight of aromatic resin, from 0.05 to 30% by weight of plasticizer, used by thermofusion, to improve cutting and / or eliminate migration phenomena plasticizers and their effects.

Preferably, the modified EPDM, EPM or EPM used for the formulations according to the invention will be elastomers whose presentation and rheological properties are compatible with the formulation of hot-melt adhesives such as, for example, granular presentations and grades having a Mooney viscosity at 125 ° C between 5 and 30 (ASTM D1646-95 method: ML1 + 4 at 125 ° C).

In the context of the manufacture of pressure-sensitive adhesives, the composition according to the invention is coated on a support suitable for the desired grammage, according to techniques known to those skilled in the art according to a hot-melt process using a temperature between 1 10 ° C to 160 ° C.

The pressure-sensitive adhesives obtained by coating with glues according to the invention have an instantaneous adhesive power identical, or even superior, to the pressure-sensitive adhesives containing no EPDM or EPM as an additive, after coating on a plasticized support.

The adhesives obtained by coating adhesives according to the invention on plasticized supports of the plasticized EPDM type and bitumen plates retain their initial properties during accelerated aging in an oven, in particular the adhesive power and the cohesion of the adhesive. The pressure-sensitive adhesives obtained by coating adhesives according to the invention on an absorbent support do not reveal any stain or migration after accelerated thermal aging.

Another object of the invention is the pressure-sensitive adhesives obtained by coating with an adhesive characterized by a content of 1 to 15% of EPDM or EPM polymer.

Other advantages, characteristics and applications of the invention will be better understood on reading the description which follows of exemplary embodiments. All of these elements are in no way limiting but are given by way of illustration.

The characteristics of the adhesives according to the invention and the performance of pressure-sensitive adhesives resulting from the coating of adhesives according to the invention are tested and measured by the techniques described below.

These techniques make it possible to highlight the role of additives making it possible to act against the migration phenomena of plasticizers, EPDM or EPM polymers used in formulations of pressure-sensitive adhesives according to the invention.

Instant adhesive strength measurement:

This method makes it possible to control instant adhesion or “tack” and to compare the instant adhesion of different products.

This instantaneous adhesion is expressed as the force required to take off, at a given speed, a loop of the material of which a determined surface has been previously brought into contact with a standard substrate.

A traction machine with the possibility of going back and forth of the jaw at a vertical movement speed of 300 mm / minute with an accuracy of ± 2% is used to glue a strip of adhesive 25 mm wide on a plate. glass on a 25 mm x 25 mm section, then peel off after reversing the direction of movement of the said strip.

The force necessary for a complete release of the adhesive section is measured, it is expressed in Newton. Measuring the adhesive power (180 °) at 300 mm per minute:

This method quantifies the consistency of the adhesive power of pressure-sensitive adhesives.

The peel is defined as the force required to remove, a material coated with pressure-sensitive adhesive which has been applied under precise conditions to a standardized test plate, from this test plate at a defined angle and speed.

The adhesion strength is measured 20 minutes and 24 hours after application. This measurement is carried out with a dynamometer capable of peeling an adhesive complex at an angle of 180 ° with a separation speed of 300 mm per minute with an accuracy of ± 2%.

The adhesive power is expressed as being the average of the results of the strips tested in Newton per 25 mm of width.

Accelerated aging :

The formulations after coating are placed in an oven at different temperatures and the adhesive power is measured regularly, at predetermined time intervals, by peeling tests at 100 mm per minute, in comparison with pressure-sensitive adhesive formulations, sold, used as a control.

Cutting test: This method makes it possible to predict the ease of cutting a support coated with an adhesive mass by measuring the force necessary to break a layer of given thickness of adhesive mass coated between two sheets of precut paper, by measuring the extension of the mass before breaking and observing the tendency to form wires during the application of force. The force required to break is measured, it is expressed in Newton.

EXAMPLE 1:

A pressure-sensitive adhesive composition according to the invention is obtained by mixing 20% ± 5% of rubber of the type SIS (VECTOR 4113 [EXXON ⁰ or KRATON D1161 NS (SHELL)] with 6% ± 3% of polymer of EPDM type (Nordel IP 3720 - DUPONT de NEMOURS - viscosity 20 ± 4 - diene content 0.5%), 56 , 2% ± 10% C5 type resin [Wingtac Extra (GOOD YEAR)], 17.0% ± 5% naphthenic type oil [Nyflex 222B (NYNAS)] and 0.8% ± 0.7% antioxidants [IRGANOX 1010 (CIBA)].

An adhesive is obtained whose Brookfield viscosity modulates 27-20 t / minute is 10,000 mPa.s at 180 ° C.

Its softening point is 120 ° C (Mettler method).

After coating on a plasticized EPDM support, an adhesive tape is obtained, the adhesive power of which on glass is 40 N / 2.5 cm (adhesive power at 180 ° C.)

The results of resistance to aging obtained for a formulation according to Example 1 in comparison with a formulation of DUROTAK H1540 (NATIONAL STARCH) are collated in the table below.

EXAMPLE 2

A pressure-sensitive adhesive composition according to the invention is obtained by mixing 20% ± 5% of SIS type rubber (VECTOR 41 14 (EXXON ⁰ or KRATON D1163 (SHELL)) with 10% ± 5% of polymer of EPDM type (containing two phases, one ethylene propylene rubber phase and one semi-crystalline polypropylene phase) [HiFax CA60A (MONTELL POLYOLEFINS)], 40% ± 10% of resin type, C5 [Wingtac Extra (GOOD YEAR)], 10.0% ± 5% paraffin type oil [Enerpar M 1930 (BP Chemical)], 10.0% ± 5% rosin ester (Sylvalite RE 105S (ARIZONA) and 0.5% ± 0.5% phenolic antioxidant [IRGANOX 565 (CIBA)] and 0.5% ± 0.5% phosphite antioxidant [IRGAFOS 168 (CIBA)]. An adhesive is obtained whose Brookfield viscosity modulates 27-20 t / minute is 23,000 mPa.s at 160 ° C.

Its softening point is 116 ° C (Mettler method).

After coating on a plasticized EPDM support, an adhesive tape is obtained, the adhesive power of which on glass is 36 N / 2.5 cm (adhesive power at 180 ° C.) and the adhesive power at 300 mm per minute is 55 N (measurement at 20mn).

The peak obtained during the cutting test makes it possible to predict good cutting ability.

EXAMPLE NO.3

A pressure sensitive adhesive composition according to the invention is obtained by mixing 22.1% ± 5% of SIS type rubber [KRATON D1163 (SHELL)] and 16.6% ± 5% of rubber (EUROPRENE SOL1205) with 2 % ± 0.5% of EPDM type polymer (Nordel IP 3720 - DUPONT de NEMOURS), 40% ± 10% of aliphatic resin (ESCOREZ 5400), 19.5% ± 5% of paraffin type oil [Enerpar M1930 (BP Chemical)], 0.5% ± 0.5% antioxidant [IRGANOX 1010 (CIBA)] and 0.5% ± 0.5% phosphite antioxidant [IRGAFOS 168 (CIBA)].

The peak obtained during the cutting test makes it possible to provide very good cutting ability.

Claims

1. Hot-melt adhesives, intended for the manufacture of pressure-sensitive adhesives, based on thermoplastic rubbers, comprising from 5 to 40% by weight of thermoplastic rubber, from 20 to 80% by weight of so-called tackifying resin, from 0 to 30% by weight of aromatic resin, from 0.05 to 30% by weight of plasticizer, characterized by a content of 1 to 15% of EPM or EPDM polymer.

2. Hot-melt adhesives, intended for the manufacture of pressure-sensitive adhesives, according to claim 1, characterized in that the thermoplastic rubber is chosen from copolymers comprising vinyl aromatic monomers such as styrene, butadiene, isoprene, l ethylene butylene or ethylene propylene.

3. Hot-melt adhesives, intended for the manufacture of pressure-sensitive adhesives, according to claim 2, characterized in that the thermoplastic rubber is chosen from copolymers such as Styrene-Isoprene-Styrene, Styrene-Butadiene-Styrene, Styrene-Ethylene-Butylene-Styrene or Styrene (Ethylene-

Propylene) Styrene.

4. Hot-melt adhesives, intended for the manufacture of pressure-sensitive adhesives, according to claim 1, characterized in that the plasticizer is chosen from low molecular weight oils such as paraffinic, aromatic or naphthenic oils and their mixture.

5. Use of polymers of the EPM or EPDM type as an additive in pressure-sensitive adhesive compositions based on thermoplastic rubber, comprising from 5 to 40% by weight of thermoplastic rubber, from 20 to 80% by weight of so-called tackifying resin , from 0 to 30% by weight of aromatic resin, from 0.05 to 30% by weight of plasticizer, used by thermofusion, to suppress the migration phenomena of plasticizers.

6. Adhesive tape characterized in that it is obtained by coating an adhesive composition according to claims 1, 2, 3, or 4 on a support.

7. Use of polymers of the EPM or EPDM type, as an additive in pressure-sensitive adhesive compositions based on thermoplastic rubber used by thermofusion, to improve cutting.

8. Use of polymers of EPM or EPDM type, as an additive in pressure-sensitive adhesive compositions based on thermoplastic rubber, comprising from 5 to 40% by weight of thermoplastic rubber, from 20 to 80% by weight of so-called tackifying resin , from 0 to 30% by weight of aromatic resin, from 0.05 to 30% by weight of plasticizer, implemented by thermofusion, to improve cutting.