FR2834730A1 - Water-based antislip composition, useful for making pallet security paper, comprises a thermoplastic core-shell polymer emulsion and heat-expandable microspheres - Google Patents

Abstract

Water-based antislip composition comprises: (a) 50-99 parts of an emulsion of a thermoplastic core-shell polymer in which the core has a lower glass transition temperature than the shell; and (b) 1-50 parts heat-expandable microspheres. An Independent claim is also included for water-resistant antislip substrates coated with the composition.

Description

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ANTI-SLIP COMPOSITION WITH WATER BARRIER
USEFUL IN PRESS STICKER ON PAPER MACHINE
AND ANTI-SLIDER MEDIA THUS OBTAINED
The invention relates to a composition in aqueous form for the manufacture of anti-slip media on a paper machine using a conventional gluing press, having a water barrier and without bonding between the sheets.

State of the art
The production of anti-slip media has been known for a long time; the anti-slip effect is generally obtained by coating or spraying off the machine. Three families of products obtained by these techniques are known: a. The products obtained by coating with paraffins. These products whose effectiveness is obtained by the poing effect of paraffins exhibit a phenomenon of bonding between the sheets very accentuated which limits the use of these products for manual use. b. The products obtained by coating or spraying colloidal silicas with very relative efficiency that only give satisfaction by friction on themselves. c. The products obtained by coating latex compositions and microspheres that expand under the influence of heat. To allow the expansion of these microspheres, the emulsion polymers used must have a glass transition temperature Tg of less than 35 ° C.
When the Tg is greater than 35 C the polymer film obtained after drying is too hard to allow expansion of the microspheres.
When the Tg of the polymers is less than 35 C, the coating obtained is very soft, and causes gluing problems between the sheets, particularly at high temperature and / or high humidity. A typical symptom of these collage phenomena is the difficulty of separating the sheets from one another in a pile. The addition of adjuvants to limit this phenomenon, such as: mineral or organic fillers, paraffins, waxes, starch, etc. does not solve these problems satisfactorily, and alters the values of the coefficient of friction as well as the resistance to water. On the other hand, these aqueous compositions can only be used in off-machine coating processes (flexographic or screen printing, roll coating, Mayer bars, air knife, etc.) and can not be used in a gluing press. on a paper machine because of the low value of the Tg.

 To these various products, it is necessary to add the sheets of expanded polystyrene which have the disadvantage of not being used in automatic sheet-making systems, because of their lack of rigidity.

 Patent FR 2395141 describes a conventional papermaking coating in which hollow and deformable microspheres have been incorporated, without specifying the values of Tg.

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 US Patent 2,643,048 discloses discontinuous coating of colloidal silica particles on sacks.

 JP 88 146 945 describes supports coated with crosslinkable adhesives having a Tg of less than 30 C onto which expandable microspheres are coated.

 US Pat. No. 4,753,831 describes a corrugated board coated on one or both sides with a mixture of latex and microspheres, after the manufacture of the corrugated board, without the method of coating being specified.

 JP 88 0322 897 discloses a coating comprising an adhesive (EVA, methacrylates or SBR) expandable microspheres and colloidal silica particles as antiblocking agent.

 JP 203 4671 discloses a corrugated board on which is coated with a core / shell type emulsion acrylic polymer, wherein the core Tg is greater than the Tg of the shell. The Tg of the nucleus being between 20 and 90 C; while the Tg of the envelope is between 20 and 10 C.

 JP 85 0928 discloses a nonwoven laminated with a plastic film coated with a composition comprising a latex and microspheres.

 FR 9105028 discloses a support having anti-slip properties on one side, obtained by coating a latex and microspheres, and having adhesive properties on the other side.

 EP 0 668 396 A1 discloses a process for obtaining an anti-slip corrugated board obtained by coating the covering papers with compositions comprising latexes and microspheres; the microsphere is expanded on the corrugated machine.

 JP 96, 143 610 discloses a slip composition comprising an acrylic latex, colloidal silica and alumina.

 JP 96 127,627 discloses a composition comprising a styrene acrylic latex and colloidal silica.

 JP 96 120,194 discloses a corrugated board coated with a composition comprising a styrene acrylic copolymer and silica.

 JP 927 9500 discloses an emulsion polymer having anti-slip properties obtained by copolymerization of a quaternary ammonium salt having a polymerizable double bond with an ethylenic monomer.

 JP 100 53742 discloses an anti-slip composition comprising a chlorinated vinyl emulsion polymer and / or an emulsion acrylic polymer having a film formation temperature (MFT) of -10 to 20 C with an SBR or NBR latex having a Tg of -50 C to -15 C. The composition may also contain colloidal silica (0.5 to 5%).

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 The patent application EP 1016 756 A1 describes a papermaking process with anti-slip properties using a composition comprising a latex, starch, microspheres and fillers or waxes.

This process involves coating paper on both sides, then coating the paper on a coater, and passing the paper over a fluted cylinder. The high proportion of starch relative to the latex promotes the water sensitivity of the product obtained.

 The patent JP 99 53,109 describes a mouse pad having an anti-slip surface obtained by coating a latex and microspheres.

 JP 2000 220,094 discloses a nonstick anti-slip composition comprising a SBR latex, a wax emulsion and hollow inorganic pigments having a particle size of between 5 and 200 μm.

 FR 279 10 39 discloses a corrugated anti-slip plate comprising at least one fluted layer, one side is coated with a flat sheet of paper cover and the other side is uncovered.

 JP 102 047 97 discloses a water barrier anti-slip paper coated with a water barrier composition of an emulsion polymer, ferrosilicate and microspheres.

 JP 129 271 discloses a non-sticking anti-slip composition for corrugated board comprising a copolymer obtained by copolymerization of a vinylsilane with an unsaturated ethylenic monomer, and a colloidal silica.

 The patent JP 90 13010 describes an anti-slip composition comprising an anti-slip resin (acrylic, EVA, etc.) and a sodium alginate. This composition may contain colloidal silica.

 JP 608 0953 discloses a non-tacky anti-slip composition consisting of a vinyl emulsion polymer and a terpene copolymer vinyl polymer having a Tg less than 50 C.

 JP 405 1912 discloses a paper glass in which the outer face and / or the base of the glass has anti-slip properties obtained by coating latex and microspheres.

 JP 731 6469 discloses a non-slip and non-tacky composition for pre-printed blanket of corrugated board comprising a copolymer obtained by copolymerization of an unsaturated ethylenic monomer and methacrylamide, and colloidal silica.

thermoplastique ayant une Tg 0 C et la seconde couche étant constituée d'une résine thermoplastique ayant une Tg > 90 C, de préférence mélangée à de la silice colloïdale. JP 234 997 discloses a non-slip composition used in two successive layers, the first layer being made of a resin

thermoplastic having a Tg 0 C and the second layer consisting of a thermoplastic resin having a Tg> 90 C, preferably mixed with colloidal silica.

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 JP 6248199 discloses a slip composition for printed corrugated board, comprising a copolymer obtained by copolymerization of a vinyl silane with an ethylenic monomer, and a colloidal silica treated with aluminate ions.

 JP 825 2880 discloses a corrugated board having anti-slip and hydrophobic properties, comprising a cover sheet coated with an emulsion polymer (acrylic, styrenic resin, polyurethane, vinyl or mixture thereof) and silica particles.

 JP 6313 130 discloses a printable anti-slip composition consisting of an acrylic copolymer or a polyvinyl ether and expandable microspheres.

 JP 626,4002 discloses a slip composition comprising microspheres having a density of 0.01 to 0.5 and an adhesive having a viscosity of at least 200 cps.

 EP 0549 948 A1 discloses a substrate having anti-slip properties obtained by coating a latex mixture having a Tg not less than -30 C and microspheres.

 US Patent 3,864,181 discloses a composition and method for making foam polymers comprising a solvent polymer solution and microspheres. This composition can be used for anti-slip bedding, carpet, tool handles, and athletic equipment.

 The inventor has discovered a new class of polymers of the core / shell type, which makes it possible to obtain high-performance, water-barrier anti-slipping supports and having a very good resistance to bonding between the sheets; these polymers also permitting the coating of paper in gluing press, under the normal conditions of papermaking; thus eliminating a sleeping step off machine.

 The term "core / shell polymer" means a polymer whose elementary particles comprise in their structure at least two different Tg.

 Core / shell polymers are described in Journal of Macromelocular Science-chem. A7 (3), pages 623-646 (1973) by D. J. Williams et al.

 The measurements of Tg are performed by dsc (differential scanning calorimetry).

 In the case of polymer blending, the Tg is calculated according to the Fox equation.

 A technique different from that described by D.J. Williams, for obtaining envelopes having a different Tg of the core is to use polymeric active voltages as stabilizers of the emulsion polymerization process, which graft onto the elementary particles, to form the envelope. This gives a core / shell type polymer having a very thin envelope which has the

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 peculiarity of having a film formation temperature close to the Tg of the nucleus; while conventional core / shell polymers have a film-forming temperature close to the Tg of the shell.

 It is this category of polymer that has been used in the examples described.

As a result, it is not necessary to use coalescing agents. The very low temperature of film formation, furthermore allows the formation of a thermoplastic film immediately after evaporation of the water which retains the microspheres, reinforcing the cohesion between the thermoplastic film and the microspheres, thus avoiding the dusting phenomenon, sometimes observed. The smaller amount of microspheres required also limits these dusting phenomena.

 The absence or the small amount of charges necessary, as well as the absence of starch or other substances sensitive to water, makes it possible to obtain a slip-resistant support having good water resistance.

 These anti-slip supports are used as pallet spacers and placed directly on the pallets and between the cartons. Pallets often have a very high moisture content, and this humidity rises in the packing boxes. The barrier to water obtained with the products described, avoids this phenomenon, because on the automatic packaging lines, it is not possible to manually insert a protective plastic film between the pallets and cartons of packaging.

The products obtained according to the invention therefore have a dual function:
1-Anti-slip to stabilize products during transport
2-Protection of packaging against moisture.

que la température de transition vitreuse Tg du noyau est inférieure à V > celle de l'enveloppe. b. Des microsphères expansibles à la chaleur consistant en des particules sphériques à base de PVdC ou PVdC/acrylonitrile encapsulant un gaz. Summary of the invention
The invention relates to a coating composition for coating water-resistant non-slip substrates without interspirical bonding, and for coating paper in a papermaking machine, this composition comprises: a. A core / shell type emulsion polymer characterized by the fact

that the glass transition temperature Tg of the core is less than V> that of the envelope. b. Heat expansive microspheres consisting of spherical particles based on PVdC or PVdC / acrylonitrile encapsulating a gas.

Detailed Description of the Invention The aqueous compositions of the invention comprise: 1-A core / shell type emulsion polymer. The polymer constituting the core having a Tg lower than that of the envelope. The
Tg of the core is preferably chosen between -540C and 20 C. The Tg of the envelope is preferably chosen between 40 C and 120 C.

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 When the Tg of the envelope is lower than 35 C the composition becomes too soft, and causes problems of bonding between the sheets, especially at high temperature and / or high humidity.

 The very low Tg of the core, and the very thin envelope of the polymers used also gives the latex non-slip properties without sticking, even with a large Tg of the envelope, which gives a synergistic effect between the latex and the microspheres. The Tg of the envelope must, however, be limited to 120 ° C because, beyond this, the synergistic effect observed is lost.

 It has also been observed that the tendency to stick between sheets depends on the acid number of the polymers used; the higher the acid number and the lower the blocking, the resistance to water varies in the opposite direction. The best compromise is to choose polymers having an acid number between 40 and 150.

 The presence of a low Tg core allows on the other hand, the rapid expansion of the microspheres.

sphères creuses varie de 5 à 17 microns et ont une densité réelle de 1000 3 à 1300 kg/m3. Quand elles sont chauffées, le gaz à l'intérieur augmente la pression et l'enveloppe thermoplastique ramollit, résultant en une augmentation du volume des microsphères. Elles sont préférées aux

agents gonflantes traditionnels, car elles gonflent à plus basse température. e
La fabrication de ces microsphères est décrite dans les brevets US
4,287, 308 et US 3,615, 972. 2-microspheres which consist of a polymer envelope encapsulating a gas (butane, isobutane, propane ...). The diameter of cases

hollow spheres range from 5 to 17 microns and have a real density of 1000 3 to 1300 kg / m3. When heated, the gas inside increases the pressure and the thermoplastic shell softens, resulting in an increase in microsphere volume. They are preferred to

traditional swelling agents because they swell at a lower temperature. e
The manufacture of these microspheres is described in US Patents
4,287,308 and US 3,615,972.

 3-additives favoring the coating according to the type of coating used (thickening water retainers, defoamers, lubricants, dispersants, surfactants, fillers, colorants, etc ...).

 4-Possibly crosslinking agents which harden the polymeric film obtained after drying, further limiting the risks of sticking, such as urea formaldehyde resins, ZnO, styrene maleic anhydride oligomers (SMA), polyfunctional azidines, resins melanin formaldehyde, isocyonates, multifunctional epoxies, alkoxysilanes, aminosilanes, vinyl silanes, methacrylalkoxysilanes, epoxy silanes or zirconium salts.

 These crosslinking agents which completely eliminate the risk of sticking further improve the water barrier properties.

 The slip compositions thus compound comprise: a. From 50 to 99 parts by weight of a thermoplastic emulsion polymer of core / shell type and whose core Tg is less than the Tg of the shell. b. From 1 to 50 parts by weight of heat-expandable microspheres.

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 c. Additives promoting the coating. d. Crosslinking agents.

 The core / shell type polymers such as those previously described, and whose core Tg is very low (<-10 ° C.), have anti-slip properties by themselves, for coating thicknesses of the order of 8 to 10. u. m.

 The cost of these coatings being too high and such polymer thicknesses can not be applied in paper machine gluing press, it has appeared useful to add microspheres to reduce the amount of latex required. The anti-slip effect obtained by the microspheres creates a synergistic effect with the core / shell polymers; which reduces the amount of latex, and also the amount of. microspheres compared to formulations not using core / shell polymers, this is illustrated by the examples cited.

 The amount of microspheres required is also lower than in the case of using conventional latexes, which can not be used in gluing press.

Without being limiting, the monomers used for the manufacture of core / shell polymers are as follows:

régler les différents Tg des polymères utilisés. <Tb>
<tb> Monomers <SEP> Tg <SEP> C
<tb> Methyl <SEP> Methacrylate <SEP> 105
<tb> Butyl <SEP> methacrylate <SEP> 65
<tb> Butyl <SEP> acrylate-54
<tb> Styrene <SEP> 100
<tb> Ethyl-Hexy <SEP>! <SEP> acrylate-50
<tb> Acid <SEP> acrylic <SEP> 106
<tb><SEP> methacrylic acid <SEP> 228
<tb> Hydroxyethyl <SEP> acrylate-15
<tb> Hydroxyethyl <SEP> methacrylate <SEP> 55
<Tb>
It is the choice of these different monomers and their ratio which makes it possible to

adjust the different Tg of the polymers used.

film proche de la Tg de l'enveloppe, alors que les polymères noyau/enveloppe de t > l'invention ont une température de formation de film proche de la Tg du noyau. t > IZ>
Polymers of this type have been used for transparent protective coatings for the production of electrophotographic or xerographic films (Patent WO 96/16357) or for heat-sensitive recording media with a protective layer (Patent FR 2 742 380) allowing obtain soft varnishes without residual tack, with the difference that the core / shell polymers used in these patents have a temperature of formation of

film close to the Tg of the envelope, whereas the core / shell polymers of the invention have a film formation temperature close to the Tg of the core. t>

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The following examples are given by way of illustration, and do not limit the scope of the invention described in the claims. The anti-slip values were measured by the inclined plane method, by applying a weight of 220 g to the treated paper, itself applied to a varnished cardboard. The Cobb measurements were performed according to standard NF 20535-ISO 535 with a contact time of 60 seconds. The blocking tests were carried out in the following manner: about fifty R / V treated anti-slip sheets are stacked and subjected to a pressure of 2 kg / cm 2 at 500 ° C. for 24 hours; the bonding is observed after reconditioning at room temperature.

en émulsion 1000 1 Extrait sec = 15 % Viscosité = 80 cps Poids déposé humide = 25 g/m2.

or M2 Poids déposé en sec = 3. 75 g/m2 dont 0. 5 g/m2 de microsphères et 1.9 g/m2 de latex EXEMPLE 2

Un papier de couverture pour carton ondulé de 150 g/m2 est couché sur les Z : D deux faces hors machine à l'aide d'une coucheuse lame d'air avec la composition suivante :
Eau 635 1
Silice FK 320 15 kgs (Degussa) EXAMPLE 1
A 150 g / m2 corrugated paper cover paper is coated on both sides off machine using an air knife coater with the following composition:
Water 685 1
Silica FK 320 15 kgs (Degussa)
Latex SBR 150 1 dry extract = 50% by weight (Tg 20 C)
Microspheres 820 WU 50 1 Dry extract = 40% by weight (Expancel)
Microcrystalline wax 100 1 Dry extract = 40% by weight

in emulsion 1000 1 Dry extract = 15% Viscosity = 80 cps Wet deposited weight = 25 g / m2.

Gold M2 Weight deposited in dry = 3. 75 g / m2 including 0. 5 g / m2 of microspheres and 1.9 g / m2 of latex EXAMPLE 2

A 150 g / m2 corrugated paper cover is laid on the Z: D two off-machine sides using an air knife coater with the following composition:
Water 635 1
Silica FK 320 15 kgs (Degussa)

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Latex SBR 150 1 dry extract = 50% by weight (Tg 20 C)
Microspheres 820 wu 100 1 Dry extract = 40% by weight (Expancel)
Microcrystalline wax 100 1 Dry extract = 40% by weight
1000 1
Dry extract = 17%
Viscosity = 80 cps
Wet weight = 25 g / m2
Dry weight = 4.25 g / m2 including 1 g / m2 of microspheres and 1.9 g / m2 of latex
EXAMPLE 3
A 150 g / m2 corrugated paper cover paper is coated on both sides off machine using an air knife coater with the following composition:
Water 335 1
Acrylic Latex 660 1 Dry Extract = 50% by Weight Core Envelope
Joncryl 2640 (Johnson Polymer) Core Tg = - 380C
Tg of the envelope = 115 C
Acid number 65 Epoxysilane A-187 0.5 1 Dry extract = 100% by weight (OSI SPECIALTIES)
1000 liters
Dry extract = 31. 7%
Viscosity = 100 cps
Wet weight = 25 g / m2
Dry weight deposited = 8 g / m2
EXAMPLE 4
A blanket of 150 g / m2 corrugated board is laid on both sides off-machine using an air knife coater with the following composition:

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Dont 1. 8 g/m2 de latex t > et 0. 5 g/m2 de microsphères
EXEMPLE 5
Un papier de couverture pour carton ondulé de 150 g/m2 est couché sur les deux faces hors machine à l'aide d'une coucheuse lame d'air avec la composition suivante :
Eau 785 1
Latex noyau/enveloppe 150 1 Extrait sec = 48 % en poids
Joncryl 2647 (Johnson Polymer)
Indice d'acide 65 Tg du noyau = - 330C
Tg de l'enveloppe = 116 C
Indice d'acide 65
Silice colloïdale 15 kgs Extrait sec = 30 % en poids
Klebosol 30R50 (Hoechst)
Microsphère 820 WU 50 1 Extrait sec = 40 % en poids (Expancel)
1000 litres Water 795 1 Latex acrylic 150 1 Dry extract = 48% by weight core / shell Joncryl 2640 (Johnson Polymer) Tg of the core = - 380C Tg of the shell = 115 C Acid number 65 Epoxysilane A-187 0.5 1 Dry extract = 100% by weight (OSI SPECIALTIES) Microspheres 820 WU 50 1 Dry extract = 40% by weight (Expancel)
1000 liters Dry extract = 9.25% Viscosity = 55 cps Dry weight deposited = 235 g / m2

Of which 1.8 g / m 2 of latex and 0.5 g / m 2 of microspheres
EXAMPLE 5
A 150 g / m2 corrugated paper cover paper is coated on both sides off machine using an air knife coater with the following composition:
Water 785 1
Latex core / shell 150 1 Dry extract = 48% by weight
Joncryl 2647 (Johnson Polymer)
Acid value 65 Tg of the core = - 330C
Tg of the envelope = 116 C
Acid number 65
Colloidal silica 15 kgs Dry extract = 30% by weight
Klebosol 30R50 (Hoechst)
Microsphere 820 WU 50 1 Dry extract = 40% by weight (Expancel)
1000 liters

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Tg du noyau =-33 C ZD Tg de l'enveloppe = 116 C Indice d'acide 55 Polycrylate RT5 Coatex 5 1 Extrait sec = 45 % en poids Antimousse TEGO 5 1 Foamex 805 (Tego Chemie GmbH) ZnO Solution 1 25 1 Extrait sec = 15 % en poids (Johnson Polymer) Ammoniaque pour pH 9 9.5 Silice colloïdale 30R50 50 1 Extrait sec = 30 % en poids (Hoechst) Microsphère 820 WU 150 1 Extrait sec = 40 % en poids (Expancel)
1000 litres Extrait sec = 32,6 % Viscosité = 80 cps Dry extract = 9. 25%
Viscosity = 65 cps
Wet weight = 25 g / m2
Of which 1. 8 g / m2 of latex and 0.5 g / m2 of microspheres
EXAMPLE 6
A 150 g / m2 corrugated paper covering paper is coated on a paper machine using a vertical glue press during paper making. The support paper is bonded in the mass in a known manner using an alumina / rosin sulphate mixture so as to obtain a support having a Cobb 1 mm of 25 g / m 2 before entering the sizing press, and a humidity rate of less than 8%. The following composition is then introduced into the gluing press:
Water 265 1
Latex core / shell 150 1 Dry extract = 48% by weight
Joncryl 2640 (Johnson Polymer)

Tg of core = -33 C ZD Tg of shell = 116 C Acid number 55 Polycrylate RT5 Coatex 5 1 Dry extract = 45% by weight Antifoam TEGO 5 1 Foamex 805 (Tego Chemie GmbH) ZnO Solution 1 25 1 Extract dry = 15% by weight (Johnson Polymer) Ammonia for pH 9 9.5 Colloidal silica 30R50 50 1 Dry extract = 30% by weight (Hoechst) Microsphere 820 WU 150 1 Dry extract = 40% by weight (Expancel)
1000 liters Dry extract = 32.6% Viscosity = 80 cps

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The support is coated on both sides, with a wet deposit of 8 g / m 2 per side and dried post-drying conventionally.

Dry weight deposited latex = 1. 9 g / m2
Dry weight of microspheres = 0. 48 g / m2
Although the latex has a Tg of -33 for the core, an average Tg of -18 C and a film formation temperature of less than -5 C, this composition is perfectly usable in gluing press, without sticking on the presses, with a very low charge rate.

 A conventional latex used under these conditions would have irretrievably led to gluing on the presses, rendering the process unusable.

 It is the very high temperature (116 C) of the Tg of the envelope which makes this composition usable in gluing press.

EXAMPLE 7
A 300 g / m2 corrugated paper cover paper is coated on a paper machine using a vertical gluing press during paper making. The support paper is bonded in the mass in known manner with alkyl ketene dimer (Aquapel &commat; 315 Hercules-AKD) so as to obtain a support having a Cobb 1 mm 25 g / m 2 before entry into size-press and a moisture content of less than 8%. The following composition is then introduced into the sizing press.

Water 215 1
Kernel / shell latex 520 1 Dry extract = 48% by weight
Joncryl 2640 (Johnson Polymer) Core Tg = - 380C
Tg of the envelope = 115 C
Acid number 55
Polyvinyl Alcohol 5 1 OVAL 117 (Kuravay)
Antimousse TEGO 5 1
Foamex 805 (Tego Chemie GmbH)
ZnO Solution 1 20 Dry extract = 15% by weight (Johnson Polymer)
Ammonia for pH 9 9.5 CaC03 in slurry 150 1 Dry extract = 75% by weight

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Microsphere 007 WU 85 1 Dry extract = 74% (Expancel)
1000 liters
Dry extract = 43.75%
Viscosity = 90 cps
Wet deposited weight = 8 g / m2 / face
Of which 2 g / m 2 of latex and 0.5 g / m 2 of microspheres
The support is then dried post drying in a conventional manner.

EXAMPLE 8
A 150 g / m2 corrugated paper cover paper is coated on a paper machine using a size press under normal papermaking conditions. The paper is pasted as in the previous example.

 The same formula as in Example 7 was introduced into the gluing press, in which the Joncryl 2640 latex was replaced by the Joncryl 8051 acrylic latex in which the core Tg is -23 C, the Tg of the envelope 110 C and the acid number 74.

The results of these different examples are summarized in the following table:

<Tb>
<tb> Nature <SEP> of <SEP> latex <SEP> Tg C <SEP> Weight <SEP> Weight <SEP> deposited <SEP> Angle <SEP> of <SEP> Cobb <SEP> Paste
<tb> deposited <SEP> mierosphere <SEP> slid <SEP> g / m2 <SEP> between <SEP>
<tb> latex <SEP> g / m2 <SEP> degrees <SEP> leaves
<tb> g / m2
<tb> Example <SEP> 1 <SEP> SBR <SEP> 20 <SEP> 1. <SEP> 9 <SEP> 0. <SEP> 5 <SEP> 30 <SEP> 30 <SEP> YES
<tb> 1 <SEP> Example <SEP> 2 <SEP> SBR <SEP> 20 <SEP> 19 <SEP> 1 <SEP> 43 <SEP>: <SEP> 15 <SEP> YES
<tb> Exempt <SEP> 3 <SEP> Acrylic <SEP> Core = <SEP> -38 <SEP> 8 <SEP> 0 <SEP> 36 <SEP> 2 <SEP> NO
<tb> Core / Envelope <SEP> Envel <SEP> = <SEP> 115
<tb> Exempt <SEP> 4 <SEP> Acrylic <SEP> Core <SEP> = <SEP> - <SEP> 38 <SEP> 1. <SEP> 8 <SEP> 0. <SEP> 5 <SEP> 45 <SEP> 4 <SEP> NO
<tb> Core / Envelope <SEP> Envel <SEP> = <SEP> 115
<tb> Example <SEP> 5 <SEP> Acrylic <SEP> Core = <SEP> -33 <SEP> 18 <SEP> 05 <SEP> 42 <SEP> 6 <SEP> NO
<tb> Core / Envelope <SEP> EnveL = <SEP> 116
<tb> Example <SEP> 6 <SEP> Acrylic <SEP> Core <SEP> = -38 <SEP> 1. <SEP> 9 <SEP> 05 <SEP> 45 <SEP> 5 <SEP> NO
<tb> Core / Envelope <SEP> Envel. <SEP> = <SEP> 115
<tb> Example <SEP> 7 <SEP> Acrylic <SEP> Core <SEP> = -38 <SEP> 2 <SEP> 0. <SEP> 5 <SEP> 43 <SEP> 6 <SEP> NO
<tb> Core / Envelope <SEP> Envel. <SEP> = <SEP> 115
<tb> Example <SEP> 8 <SEP> Acrylic <SEP> Core <SEP> = -23 <SEP> 2 <SEP> 0. <SEP> 5 <SEP> 43 <SEP> 7 <SEP> NO
<tb> Core / Envelope <SEP> Envel. <SEP> = <SEP> 110
<Tb>

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 The following conclusions can be drawn from these various examples: a) The conventional latices currently used for the manufacture of anti-slip substrates necessarily have a Tg <35 C. This type of latex causes problems of bonding at high temperature and / or high humidity. .

de poudrage rencontrés lorsque le rapport pondéral microsphères/liant est c plus important. La formation du film polymérique à basse température avec les microsphères, limitant encore le poudrage, qui pose des problèmes d'hygiène et sécurité dans les ateliers, et des problèmes d'impression. d) Pour des formules comparables, il a été observé que la résistance à l'eau est d'autant meilleure, que l'indice d'acide est plus faible, comme le montre la différence entre les exemples 7 et 8. e) L'utilisation de polymères en émulsion de type noyau/enveloppe avec un noyau ayant une Tg inférieure à la Tg de l'enveloppe permet l'utilisation de ces compositions en presse encolleuse conventionnelle sur machine à papier dans les conditions normales de fabrication du papier, le séchage des couches et l'expansion des microsphères étant réalisés dans le poste de post-sécherie. Seule la vitesse de production est légèrement ralentie. The addition of adjuvants to limit this phenomenon does not solve these problems fully satisfactory because of the low value of the Tg, there is migration of adjuvants in the thermoplastic layer and all the more so that the temperature is higher. b) On the other hand, the adjuvants used to limit the bonding between sheets (starch, mineral fillers, etc.) increases the sensitivity to water, as shown by the Cobb values of Examples 1 and 2. Examples 3 to 8 demonstrate that the use of core / shell type latex solves bonding problems, even with low or no charge levels as in Example 4. c) The core / shell latices used show a synergistic effect of the properties anti-slip, which allows to lower the amount of microspheres necessary to have a good anti-slip level, as shown by the difference between Example 1 and Examples 3 to 8. In addition to the economic aspect, the smallest amount of microspheres limits the problems

when the weight ratio microspheres / binder is greater. The formation of low temperature polymeric film with microspheres, further limiting dusting, which poses health and safety problems in the workshops, and printing problems. d) For comparable formulas, it has been observed that the water resistance is all the better, as the acid number is lower, as shown by the difference between Examples 7 and 8. e) L The use of core / shell type emulsion polymers with a core having a Tg less than the Tg of the shell allows the use of these compositions in conventional papermaker sizing press under normal papermaking conditions. drying of the layers and the expansion of the microspheres being carried out in the post-drying station. Only the speed of production is slightly slowed down.

 These core / shell polymers also make it possible to limit the amount of adjuvants necessary to avoid sticking on the size-press cylinders, which also makes it possible to obtain supports having a good resistance to water.

 It is thus possible to produce a more efficient product in terms of anti-slip properties, water barrier and resistance to sticking at a lower cost.

Claims (16)

1) An antislip composition in aqueous form, which can be used for the production of anti-slip paper using a conventional gluing machine on paper machine, water barrier and without bonding between the sheets comprising: a) From 50 to 99 parts of a thermoplastic emulsion polymer of core / shell type, and whose core Tg is less than the Tg of the envelope. b) From 1 to 50 parts of heat-expandable microspheres. 2) An anti-slip composition according to claim 1 wherein the Tg of the core is less than 35 C, and the Tg of the envelope is greater than 50 C. 3) An anti-slip composition according to claim 1 wherein the Tg of the core is preferably between -540C and 20C, and the temperature of the envelope preferably between 40 and 120 C. 4) An anti-slip composition according to claim 1 wherein the acid number of the thermoplastics used is between 40 and 150. 5) An anti-slip composition according to claim 1 wherein the monomers used for the manufacture of core / shell polymers used are preferably methyl methacrylate, butyl methacrylate, butyl acrylate, styrene, ethyl hexyl acrylate, acrylic acid. , methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate. 6) An anti-slip composition according to claim 1 wherein the microspheres used consist of a thermosplastic envelope encapsulating a gas. 7) An anti-slip composition according to claim 1 wherein the diameter of the microspheres varies between 5 and 20 microns. 8) An anti-slip composition according to claim 1 wherein are added conventional coating-promoting additives such as thickeners, water retainers, defoamers, lubricants, dispersants, surfactants, fillers, agents and the like. antistatic, or dyes. 9) An anti-slip composition according to claim 1 comprising a crosslinking agent based on ZnO. 10) anti-slip composition according to claim 1 comprising a cross-linking agent based on oligomers styrene maleic anhydride (SMA). <Desc / Clms Page number 16>  11) anti-slip composition according to claim 1 comprising a crosslinking agent based on polyfunctional azidines or products based on urea formaldehyde, melamine formaldehyde, isocyanates, multifunctional epoxy, alkoxysilanes, amino silanes, vinyl silanes, methacryl alkoxysilanes, epoxy silanes, or zirconium salts. 12) anti-slip composition according to claim 1 comprising a water retainer of the acrylate type, CMC, PVA, alginate hydroxyethylcelluloses or natural polymers. 13) anti-slip composition according to claim 1 comprising silica, modified or not.

14) anti-slip composition according to claim 1 comprising mineral tD loads such as kaolin, CaCO 3, TiO 2, BaSO 4. 15) Water-resistant anti-slip substrates coated with the composition according to any one of claims 1 to 14. 16) Papers, in that they have been treated with a papermachine press according to any one of claims 1 to 14.