HK1061864B - Method for treatign a mineral filler with a polydialkylsiloxane and a fatty acid, resulting hydrophobic fillers and uses thereof in polymers for breathable films - Google Patents

Description

Method for treating mineral fillers with polydialkylsiloxanes and fatty acids, hydrophobic fillers thus obtained and their use in polymers for breathable films

The present invention relates to the technical field of treated mineral fillers, in particular treated carbonates, especially calcium carbonate, and their use in industry.

More particularly, the invention relates to the treatment of such fillers to render them hydrophobic and to the incorporation of them into polymers, for example for the manufacture of films, in particular "breathable" films, which are themselves incorporated, for example, into articles such as disposable diapers and similar products.

In order to achieve industrial applications in the above mentioned fields, it is necessary to produce mineral fillers, in particular calcium carbonate, which have excellent hydrophobicity and excellent repellency to water and aqueous liquids, which can be mixed or "compounded" in suitable polymers, usually polyolefins or mixtures or compositions of polyolefins.

So-called "breathable" films in the above-mentioned applications and their desired properties are well known to those skilled in the art.

It is particularly known that: they must have very good water vapour transmission properties (which correspond to their so-called "breathable" film properties). It is believed that: the filler incorporated during stretching, particularly mono-or biaxial, helps to form micropores which may enhance the "breathability" characteristics. Thus, the filler plays a major role in the finished product obtained and its properties.

In this connection, the aspect ratio (ratio between length and mean diameter) of the filler particles must be close to 1. The filler must be free of coarse particles, in particular particles having a size greater than about 10 μm and a particle size analysis "top cut" of less than 10 μm, and the filler must contain only a small fraction of particles having an equivalent spherical diameter of less than 0.5. mu.m, i.e. the BET specific surface area of the filler must be less than 6m²/g。

Of course, the process of the design must be consistent with current regulations.

In almost all applications to which such articles are directed, the fillers incorporated cannot impair the suitability of the uniaxially or biaxially stretched or oriented plastic films. The flow properties of the filler must also be good in order not to cause predictable compounding problems during the introduction of the polymer. Of course, the filler must also be able to mix easily with the polymer and disperse uniformly in the polymer matrix, otherwise the final film will be non-uniform. The treated filler cannot release gaseous species during the introduction of the polymer, as this would create hazy and mechanically inhomogeneous regions in the film.

The treatment also does not affect the uniformity of the colour of the film obtained, i.e. a film free from specks can be obtained.

It can be seen that: the problems and requirements associated with handling such fillers are numerous and complex and often contradictory.

Calcium carbonate treated with stearic acid is known in the art in question. For example, R.Rothon, "Particulate-Filled Polymer composites", Longman, Harlow, 1995, Chapter 4, may be cited.

Fillers treated with silanes are also known (e.p. plueddemann, silaecoutting Agent, Plenum Press, new york, 1982).

Fillers treated with organopolysiloxanes having H-SiO-bonds are also known (patent EP0,257,423), but they do not make it possible to obtain fillers which can be used in the field of so-called breathable films.

Fillers treated with stearic acid and then with silicone are also known, but use is quite different.

However, current treatments with silanes result in methanol release.

Thus, the article "NMR Spectroscopic Investigations on the hydrolysics of Functional Trialcosylites" published on Zeitur Naturforschung, 54b, 155- & 164(1999) describes the release of methanol.

Patent WO 99/61521 describes carbonates that have been treated on the surface to obtain better hydrophobicity. This treatment uses stearic acid, as in patent WO 99/28050.

Patent WO 96/26240 describes flame-retardant fillers treated with fatty acids alone or with fatty acids and silicone derivatives. The polymers used in the art must be non-flammable.

Patent JP 57,182,364 describes fillers for use as facade coatings for building materials, said coatings being impermeable to water, comprising a synthetic resin and a filler treated with a flame retardant. These resins are derivatives of vinyl acetate or acrylate-vinyl acetate copolymers which are not suitable for mono-or biaxial orientation and are not designed for breathable films. The filler must have a very high particle size, up to 100 μm. An exemplary treatment of stearic acid and methylcellulose on acrylic resin is given.

Patent WO98/29481, which describes breathable films and incorporates calcium carbonate as filler, is also known. Reference is made to this document for the general overview relating to the characteristics of so-called breathable films. For fillers, the patent only shows: it may be treated "with a fatty acid such as stearic acid or behenic acid to promote bulk flow and dispersion in the polymer matrix.

Patent JP5239377 describes the use of glyceryl stearate for the preparation of fillers, but this is in order to obtain better physical properties of the resin matrix.

Patent WO 00/12434 describes the use of desiccants, in particular CaO, for the preparation of fillers to obtain breathable films suitable for the user.

Thus, the prior art on breathable films has adopted treatment with stearic acid or desiccant products of the CaO type. Stearic acid is also used to treat fillers, but the use is quite different. A combination of fatty acids and silanes is also used.

Thus, there is no outstanding trend in the prior art, except that the filler is treated with fatty acid alone or by a combination of fatty acid and silane to form a "coating".

Therefore, there is a long-felt need, and therefore a consensus, for improving breathable films, particularly films that are free of specks and free of empty spaces, and for improving the treated fillers contained in such films.

The invention relates to a method for treating mineral fillers in order to impart to them hydrophobic properties, making them suitable for incorporation into polymers for the manufacture of so-called "breathable" films, in particular polyolefin films, characterized in that the surface treatment of the fillers is carried out in two steps, the first step (pretreatment) comprising a treatment with at least one polydialkylsiloxane and the second step comprising a treatment with at least one fatty acid containing more than 10 carbon atoms, which steps can be carried out simultaneously.

Thus, as mentioned above, the present invention relates to a method of treating mineral fillers which surprisingly combines a pre-treatment first with a polydialkylsiloxane and then a treatment with a fatty acid such as stearic acid.

The two treatments combined in this order resulted in specific properties with a synergistic effect between the two treatments, as shown below.

In practice, the polydialkylsiloxane is added first, immediately followed by the fatty acid.

In some cases, however, it is possible to add both substances simultaneously, but it must be ensured that the fatty acid is never brought into contact with the filler first.

In general, it is preferred to work in two distinct steps, namely the addition of the polydialkylsiloxane and then the addition of the fatty acid.

Thus, throughout the remainder of the present application, for a two-step process, the applicant refers to a process in which: the two compounds are added in separate steps in time, even at short intervals, or substantially simultaneously, provided that the fatty acid does not come into contact with the filler prior to the polydialkylsiloxane.

More particularly, the invention is best suited for heavy calcium carbonates such as marble and calcite or mixtures thereof.

However, the invention is also suitable for fillers such as precipitated calcium carbonate, talc, kaolin, magnesium hydroxide, fillers of the various types consisting of clay, silica, alumina, barium sulfate, mica, calcium oxide or hydroxide, aluminum oxide, mixtures thereof and the like.

On the other hand, chalk does not produce good results, which clearly shows that: the likelihood of success of the present invention is absolutely not speculative.

According to a preferred embodiment, polydialkylsiloxanes having the formula: (R)₃-Si-O-[(R)₂-Si-O-]_n-Si-(R)₃Wherein the alkyl R is C1-C4.

In a particularly preferred method, Polydimethylsiloxane (PDMS) is used, wherein the R group is a methyl group.

According to a preferred embodiment, a polydimethylsiloxane having a kinematic viscosity of 50 to 100,000 centipoise (cSt), preferably 300-.

About 700-1300cSt can achieve optimal hydrophobicity.

As fatty acids, fatty acids having more than 10 carbon atoms can be used, and in a completely preferred method stearic acid, palmitic acid, behenic acid and mixtures thereof are used.

According to a preferred but non-limiting embodiment, the process of the invention is carried out according to the following steps:

-using a high-speed mixer, placing the ground filler therein,

adding the polydialkylsiloxane at about 100 ℃ over 5 minutes, at the end of these 5 minutes,

-adding a fatty acid.

In this respect, it should be noted that: the polydialkylsiloxane has the advantage of imparting non-stick properties to the mixture, the mixture does not stick to the walls of the mixer (but when the polydialkylsiloxane is not used, the mixture sticks).

Preferably, the above process is applied with marble or calcite or a mixture thereof as filler, with polydimethylsiloxane as polydialkylsiloxane and glyceryl stearate (a mixture of about 65% stearic acid and 35% palmitic acid) as fatty acid with carbon atoms greater than 10.

According to another preferred embodiment, 100-2000ppm, preferably 200-1000ppm, polydialkylsiloxane will be used relative to the weight of dry filler, and in a fully preferred process, about 500 ppm.

According to yet another preferred embodiment, 0.6-1.4%, preferably 0.8-1.2% of fatty acid relative to dry weight of dry filler will be used.

The invention also relates to the above filler, characterized in that it has been treated by the method of the invention.

The invention relates more particularly to a filler of this type, characterized in that: they have high flowability and a BET specific surface area of 2 to 6m²(iv)/g, top-cut particles of less than 10 μm, preferably less than 8 μm.

For fillers with high flowability, the applicant refers to fillers having an inclination (inclination angle) determined by the method hereinafter called "stacking method" (ratio between the inclination of the treated filler and the inclination of the untreated filler) lower than or equal to 0.98.

In practice, the tilt angle indicating the flowability of the powder is determined by weighing 150 grams of powder. The powder was then placed in a 45cm long vibratory feeder. By steady state vibration of the feeder, adjusted to 8 steps, the powder is fed forward and past the edges of the film, forming a pile of powder, which is the function of the filler. Then, the inclination angle α is calculated by the following formula: tan α -powder pile height/powder pile radius.

The smaller the angle, the better the flowability of the powder.

The invention relates more particularly to said fillers, which are characterized in that they have a high hydrophobicity, i.e. they have a turbidity index ranging from 0.9 to 1 and a foam index ranging from 0.7 to 1, both indices being determined by the method described below, known as the "spin-off method"; and they have a low moisture absorption, i.e. a moisture absorption of less than or equal to 0.42mg/m²Which is measured by a method called the amount of moisture absorption described below.

In order to measure the hydrophobicity of the filler of the invention, the so-called spin-off method consists of the following steps: 0.5 g of a sample whose hydrophobicity is desired to be determined is introduced into a vibrating test tube containing 3 ml of demineralized water. After stirring at 2000 rpm for 5 seconds, the haze determined using a UV and visible spectrometer was rated as 0 to 1. A turbidity index of 0 corresponds to a turbid supernatant and a turbidity index of 1 corresponds to clear water without any turbidity.

In the second step, 0.5 ml of 18% strength by weight hydrochloric acid was added to the diluted sample and stirred at 2000 rpm for 5 seconds.

Carbon dioxide is then evolved due to acid attack. At one end of the standard scale, strong acid attack will cause a large release of carbon dioxide, resulting in the presence of a large amount of foam, which corresponds to a foam index of 0 and zero hydrophobicity, while at the other end of the standard scale, a completely hydrophobic product does not cause carbon dioxide release, nor any foam, the foam index is 1.

The method described below, which is referred to as the hygroscopy method, is based on measuring the weight gain of a powdery sample to be tested, which is first placed in an atmosphere at a relative humidity of 10% for 5 hours at room temperature and then in an atmosphere at a relative humidity of 90% for 2 hours.

Knowing the BET specific surface area of the test specimen, the water absorption per unit surface is then determined, in g/m²。

The invention also relates to the use of all these treated fillers in any industrial sector, in particular in sectors where hydrophobic properties of the filler are required.

Advantageously, the filler treated according to the invention may be incorporated into a polyolefin alone, or in a mixture thereof, selected from, but not limited to, low density linear polyethylene, low density polyethylene, high density polyethylene and polypropylene and mixtures thereof.

The treated filler is introduced into the polyolefin or suitable polyolefin mixture in known equipment by methods known to those of ordinary skill in the art.

Reference may likewise be made to WO98/29481, which relates to the same general application, for the production of breathable films with fillers, in particular uniaxially or biaxially stretched.

In practice, the invention also relates to a process for the manufacture of so-called polyolefin "breathable" films containing at least one mineral filler of the type described above, characterized in that said filler has also been treated by the above-mentioned process.

According to the invention, the masterbatch or "batch" produced contains 20 to 80% by weight, preferably 45 to 60% by weight, in particular about 50% by weight, of the treated filler relative to the total weight.

According to a preferred embodiment, said film is subjected to mono-or biaxial stretching (or "orientation").

The invention also relates to articles comprising at least one layer of such a film, in particular products which absorb water or aqueous liquids, such as disposable diapers and similar products.

The manufacture of such products is well known to those skilled in the art because of the film stretching process.

The invention also relates to the films thus obtained in an unstretched or mono-or biaxially stretched state.

The invention also relates to a masterbatch or "batch" of polyolefin and filler treated according to the invention, i.e. before forming into a film form.

The invention relates more particularly to said masterbatches or "batches" characterized in that they have a melt volume-flow rate (MVR) greater than 6cm³10min (temperature 190 ℃, load 5 kg, die diameter 2.095 mm), measured according to ISO 1133, and they have a high thermal stability, i.e. a thermal stability, expressed by the length of the non-faded bars, greater than or equal to 20cm, according to the method called strip method below.

The thermal stability was determined by placing the batch in the form of granules into an extruder to extrude rods. The batch bar was placed in an oven set at 220 ℃ (Mathis Thermotester sold by Werner Mathis AG^TM) In (1). Once the rod was placed in the oven, it was immediately moved towards the outside of the oven at a speed of 0.833 mm/min.

The length of the bar without color change was then determined. The longer this length, the better the thermal stability of the batch.

Finally, the invention relates to the film itself, which contains at least one filler treated according to the invention.

The invention relates more particularly to said film, characterized in that: they are breathable films having a mottle index of less than 10, measured according to a method known as the "mottle viewer" method, described below.

This mottle index is defined as a dimensionless number that measures flaws on the surface of the sample structure. A low value of the spot index indicates a very homogeneous structure of the surface.

To this end, a sample of the film to be tested (20cm long, 15cm wide, 20 μm thick) is fixed with adhesive to a piece of black paper having a dot index of 2.01 in accordance with DIN A4.

The sample thus prepared was placed in a color scanner (UMAX)^TMPowerLook from Systems GmbH^TMIII) to obtain image data of the sample surface. It should be noted that: the sample must first be displayed on a screen to select areas without creases so as not to skew results for samples that are not well prepared.

The image data is then transferred to a SVGA graphics system and PapEye equipped with data from ONLY Solutions GmbH^TMIn the computer of the image analyzer to give a blob index value.

The invention also relates to all polyolefin articles, even in the form other than films, containing at least one such filler.

The invention also relates to all the uses of these films and articles in any industrial sector, in particular in sectors requiring fillers with hydrophobic properties and good redispersibility.

The invention will be better understood from a reading of the following description and of the following non-limiting examples.

Example 1:

this example relates to a method of treating a marble according to the invention, said marble having an average diameter of 1.8 μm, a top cut of less than 8 μm and a BET specific surface area of 4m for tests 1 to 7²/g。

For this reason, for the different tests of the present example, the following measurements were carried out according to the method described above.

-for mineral fillers, measuring the fluidity, hydrophobicity and moisture absorption

For the batch, MVR and thermal stability were measured

-measuring the mottle index for the film.

Test 1

This test is a comparative test using untreated marble.

The untreated filler had a pitch of 40 °, haze index of 0, foam index of 0, and moisture absorption of 0.95mg/m²。

The masterbatch or batch contained 50% by weight of mineral filler, 49.7% by weight of linear low density polyethylene and 0.3% by weight of heat stabilizer, the linear low density polyethylene having an MVR of 15.4cm, measured according to ISO 1133³/10min。

The MVR of the batch obtained was 5.2cm³10min, length of 10cm representing thermal stability. The obtained batch was used to prepare films on a "cast film" line.

The temperature of the extruder cylinder was about 240 ℃ to 250 ℃ and the temperature of the stretching device was 80 ℃.

The film was fed at a speed of 20 m/min on the first roll of the stretching apparatus and 40 m/min on the last roll of the stretching apparatus.

The mottle index of the obtained film was 31.2.

Test 2

This test illustrates the prior art and uses a marble of the type: average diameter of 1.8 μm, top cut of less than 8 μm, BET specific surface area of 4m²Per g, treated with 1% by weight of glyceryl stearate.

The filler treated had a dip angle of 45 °, haze index of 1, foam index of 0.8, and moisture absorption of 0.45mg/m²。

The masterbatch or batch contained 50% by weight of mineral filler, 49.7% by weight of the same polymer as in test 1 and 0.3% by weight of the same stabilizer as in test 1, and had a MVR of 9.3cm³Per 10min, the length representing the thermal stability was 23 cm.

Using the batch obtained, the film produced using the same equipment as in test 1 under the same operating conditions as in test 1 had a mottle index of 21.1.

Test 3

This test illustrates a reference and uses a marble of the type: average diameter of 1.8 μm, top cut of less than 8 μm, BET specific surface area of 4m²Per gram, treated with 500ppm by weight of hexadecyltrimethoxysilane.

The treated filler had a haze index of 0, a foam index of 0, and a moisture absorption of 0.88mg/m²。

The masterbatch or batch contained 50% by weight of mineral filler, 49.7% by weight of the same polymer as in test 1 and 0.3% by weight of the same stabilizer as in test 1, and had an MVR of 6.2cm³Per 10min, length of 6cm indicating thermal stability.

Using the batch obtained, the film produced using the same equipment as in test 1 under the same operating conditions as in test 1 had a mottle index of 33.3.

Test 4

This test illustrates the prior art and uses a marble of the type: average diameter of 1.8 μm, top cut of less than 8 μm, BET specific surface area of 4m²Per g, first treated with 1% by weight of glyceryl stearate and then with 500ppm of the same silane as used in the previous test.

The treated filler had a haze index of 1, a foam index of 0.75 and a moisture absorption of 0.43mg/m²。

The masterbatch or batch contained 50% by weight of mineral filler, 49.7% by weight of the same polymer as in test 1 and 0.3% by weight of the same stabilizer as in test 1, and had a MVR of 9.5cm³Per 10min, the length representing the thermal stability was 23 cm.

Using the batch obtained, the film produced using the same equipment as in test 1 under the same operating conditions as in test 1 had a mottle index of 21.0.

Test 5

This test illustrates a reference and uses a marble of the type: average diameter of 1.8 μm, top cut of less than 8 μm, BET specific surface area of 4m²Per g, treated with 500ppm by weight of a polydimethylsiloxane having a kinematic viscosity of 1000 cSt.

The treated filler had a haze index of 0, a foam index of 0, and a moisture absorption of 0.80mg/m²。

The masterbatch or batch contained 50% by weight of mineral filler, 49.7% by weight of the same polymer as in test 1 and 0.3% by weight of the same stabilizer as in test 1, and had an MVR of 6.1cm³Per 10min, length of 6cm indicating thermal stability.

Using the batch obtained, the film produced using the same equipment as in test 1 under the same operating conditions as in test 1 had a mottle index of 29.7.

Test 6

This test illustrates the invention and uses a marble of the type: average diameter of 1.8 μm, top cut of less than 8 μm, BET specific surface area of 4m²Per g, treated with 500ppm of a polydimethylsiloxane having a kinematic viscosity of 1000cSt and then with 1% of glycerol stearate.

The filler thus treated had an inclination of 36 °, an R-ratio of 0.9, a haze index of 1, a foam index of 0.8 and a moisture absorption of 0.39mg/m²。

The masterbatch or batch contained 50% by weight of mineral filler, 49.7% by weight of the same polymer as in test 1 and 0.3% by weight of the same stabilizer as in test 1, and had a MVR of 9.2cm³Per 10min, the length representing the thermal stability was 23 cm.

Using the batch obtained, the film produced using the same equipment as in test 1 under the same operating conditions as in test 1 had a mottle index of 7.6.

Test 7

This test illustrates the invention and uses a marble of the type: average diameter of 1.8 μm, top cut of less than 8 μm, BET specific surface area of 4m²Per g, treated simultaneously with 500ppm of a polydimethylsiloxane having a kinematic viscosity of 1000cSt and 1% of glycerol stearate.

The filler thus treated had an inclination of 36 °, an R-ratio of 0.9, a haze index of 1, a foam index of 0.9 and a moisture absorption of 0.42mg/m²。

The masterbatch or batch contained 50% by weight of mineral filler, 49.7% by weight of the same polymer as in test 1 and 0.3% by weight of the same stabilizer as in test 1, and had a MVR of 9.4cm³Per 10min, the length representing the thermal stability was 20 cm.

Using the batch obtained, the film produced using the same equipment as in test 1 under the same operating conditions as in test 1 had a mottle index of 7.8.

Test 8

This test illustrates the invention and uses a marble of the type: an average diameter of 1.8 μm, a top cut of 10 μm, a BET specific surface area of 2.4m²Per g, using 300ppm of polydimethylsiloxane having a kinematic viscosity of 1000cSt and treated with 0.6% glyceryl stearate.

The filler thus treated had an inclination of 34 °, an R-ratio of 0.85, a haze index of 0.9, a foam index of 0.8, and a moisture absorption of 0.42mg/m²。

The masterbatch or batch contained 50% by weight of mineral filler, 49.7% by weight of the same polymer as in test 1 and 0.3% by weight of the same stabilizer as in test 1, and had a MVR of 9.7cm³Per 10min, the length representing the thermal stability was 20 cm.

Using the batch obtained, the film produced using the same equipment as in test 1 under the same operating conditions as in test 1 had a mottle index of 9.9.

Test 9

This test illustrates the invention and uses such precipitated calcium carbonate: an average diameter of 1.4 μm, a top cut of 7 μm, a BET specific surface area of 5.3m²Per g, treated with 500ppm of polydimethylsiloxane having a kinematic viscosity of 1000cSt and with 1.3% of glycerol stearate.

The filler thus treated had an inclination of 36 °, an R-ratio of 0.9, a haze index of 0.95, a foam index of 0.9, a moisture absorption of 0.37mg/m²。

The masterbatch or batch contained 50% by weight of mineral filler, 49.1% by weight of the same polymer as in test 1 and 0.3% by weight of the same stabilizer as in test 1, and had a MVR of 9.1cm³Per 10min, the length representing the thermal stability was 22 cm.

Using the batch obtained, the film produced using the same equipment as in test 1 under the same operating conditions as in test 1 had a mottle index of 9.1.

Test 10

This test illustrates the invention and uses a marble of the type: average diameter of 1.8m, top cut of less than 8 μm, BET specific surface area of 4m²Per g, with 500ppm kinematic viscosity 1000cStPolydimethylsiloxane, and treated with 1.2% behenic acid.

The filler thus treated had an inclination of 36 °, an R-ratio of 0.9, a haze index of 1, a foam index of 0.9, and a moisture absorption of 0.40mg/m²。

The masterbatch or batch contained 50% by weight of mineral filler, 49.7% by weight of the same polymer as in test 1 and 0.3% by weight of the same stabilizer as in test 1, and had a MVR of 9.2cm³Per 10min, the length representing the thermal stability was 23 cm.

Using the batch obtained, the film produced using the same equipment as in test 1 under the same operating conditions as in test 1 had a mottle index of 8.4.

It should be noted that: unlike runs 6-10 of the present invention, run 3, which used silane without stearic acid, caused a large methanol release (in an amount greater than 1500ppm per volume).

In test 4, which combines stearic acid and silane, the same methanol release was observed.

Use of Drager according to the use guidelines of Drager Sicherheitstechnik GmbH, Lubeck, Germany, month 11 1999 (fifth edition)^TMTube 8101631 measures the amount of methanol released during the treatment.

All results obtained in these tests are listed in table 1 below.

TABLE 1

		Comparison of	Prior Art	Comparison of	Prior Art	Comparison of	The invention	The invention	The invention	The invention	The invention
												Test of		1	2	3	4	5	6	7	8	9	10
Method of producing a composite material	Treatment of	-	1% glyceryl stearate	0.05% silane	1% glyceryl stearate + 0.05% silane	0.05％PDMS	0.05% PDMS + 1% glyceryl stearate	0.05% PDMS + 1% glyceryl stearate, with	0.03% PDMS + 0.6% glyceryl stearate	0.05% PDMS + 1.3% glyceryl stearate	0.05% PDMS + 1.2% behenic acid
												Filler material	"spin-off method": a) index of turbidity	0.0	1.0	0.0	1.0	0.0	1.0	1.0	0.9	0.95	1.0
b) Index of foam	0.0	0.8	0.0	0.75	0.0	0.8	0.9	0.8	0.9	0.9
											Moisture absorption amount (mg/m)2)		0.95	0.45	0.88	0.43	0.80	0.39	0.42	0.42	0.37	0.40
Batch	MVR(cm2/10min)	5.2	9.3	6.2	9.5	6.1	9.2	9.4	9.7	9.1													9.2
											Thermal stability (cm)	10	23	6	23	6	23	20	20	22	23
	Film(s)	Index of spots	31.2	21.1	33.3	21.0	29.7	7.6	7.8	9.9												9.1	8.4

PDMS: polydimethylsiloxane

The results in table 1 show that: only the test of the present invention can produce films with a speck index of less than 10 and high hydrophobicity (i.e., haze index of 0.9-1, foam index of 0.7-1), low moisture pick-up (i.e., moisture pick-up of less than 0.45mg/m as measured by the method described above)²) And also to prepare a volume flow index (MVR) measured according to ISO 1133 of greater than 9cm³A masterbatch of/10 min (temperature 190 ℃, load 5 kg, die diameter 2.095 mm) and high thermal stability (i.e. a thermal stability of 20cm or more, expressed as the length of the colorfast strip, according to the method described above).

The invention also covers all embodiments and all uses which would be directly understood by one of ordinary skill in the art upon reading this application, based on his own knowledge and possibly also simple routine tests.

Claims (37)

1. A method for treating mineral fillers with the aim of imparting hydrophobic properties to them so as to render them suitable for incorporation into the production of so-called "breathable" films, said fillers being marble, calcite, precipitated calcium carbonate or mixtures thereof, characterized in that the surface treatment of the fillers is carried out in two steps, a first step of pretreatment by addition of at least one polydialkylsiloxane and a second step of treatment by addition of at least one fatty acid containing more than 10 carbon atoms.

2. A process for treating mineral fillers with the aim of imparting hydrophobic characteristics to the mineral fillers so as to render them suitable for incorporation into the production of so-called "breathable" films, said fillers being marble, calcite, precipitated calcium carbonate or mixtures thereof, characterized in that the surface treatment of the fillers is carried out by simultaneous addition of at least one polydialkylsiloxane and at least one fatty acid containing more than 10 carbon atoms.

3. A process according to claim 1, characterized in that the two additions are carried out simultaneously, but with the proviso that the fatty acids never come into contact with the filler first.

4. A process according to claim 3, characterised in that the polydialkylsiloxane can be added first and then the fatty acid immediately.

5. A process according to any one of claims 1 to 4, characterized in that a polydialkylsiloxane having the following structural formula is used: (R)₃-Si-O-[(R)₂-Si-O-]_n-Si-(R)₃Wherein R is a C1-C4 alkyl group, and n has a value such that the kinematic viscosity of the polydimethylsiloxane is from 50 to 100,000 centipoise.

6. A process according to claim 5, characterized in that R is methyl.

7. The process according to claim 5, characterized in that the kinematic viscosity is 300-.

8. A process according to claim 7, characterized in that the kinematic viscosity is 1000 centipoise.

9. A process according to any one of claims 1 to 4, characterized in that the treatment is carried out using stearic acid, palmitic acid, behenic acid or mixtures thereof as fatty acid.

10. A method according to claim 1, characterized in that the method is carried out as follows:

-using a high-speed mixer, placing the ground filler therein,

adding the polydialkylsiloxane at about 100 ℃ over 5 minutes, and at the end of these 5 minutes,

-adding a fatty acid.

11. A process according to any one of claims 1 to 4, characterized in that marble or calcite or a mixture thereof is used as filler, polydimethylsiloxane as polydialkylsiloxane and glyceryl stearate as fatty acid having a number of carbon atoms greater than 10.

12. Process according to any one of claims 1 to 4, characterized in that 100 and 2000ppm of polydialkylsiloxane, based on the weight of dry filler, are used.

13. Process according to claim 12, characterized in that 200-1000ppm of polydialkylsiloxane, based on the weight of dry filler, are used.

14. A process according to claim 13, characterised in that 500ppm of polydialkylsiloxane, based on the weight of dry filler, is used.

15. A process according to any of claims 1 to 4, characterised in that 0.6 to 1.4% by weight of fatty acid based on the weight of dry filler is used.

16. A process according to claim 15, characterized in that 0.8-1.2% by weight of fatty acid based on the weight of dry filler is used.

17. Mineral fillers, characterized in that they have been treated with a method according to any one of claims 1 to 16.

18. Mineral fillers according to claim 17, characterized in that they have a high flowability, i.e. an inclination angle ratio, measured by the method known as "stacking method", lower than or equal to 0.98; in that they have a specific surface area of 2 to 6m²(iv)/g, top cut particle analysis less than 10 μm.

19. Mineral filler according to claim 18, characterized in that the analysis of the top-cut particles is less than 8 μm.

20. The mineral filler according to claim 17, characterized in that they have a high hydrophobicity, i.e. they have a turbidity index of 0.9 to 1 and a foam index of 0.7 to 1, both indices being determined by the so-called "spin-off method"; in that they have a low moisture absorption, i.e. a moisture absorption of less than or equal to 0.42mg/m²This is measured by the known moisture absorption method.

21. Use of the treated filler of claim 20 in any industrial sector where a filler with hydrophobic properties is desired.

22. Use of the treated filler of claim 20 in the manufacture of a so-called breathable film.

23. A process for the manufacture of a so-called polyolefin "breathable" film comprising at least one mineral filler, characterized in that said filler is a filler according to claim 20.

24. The method according to claim 23, characterized in that the polymer matrix is selected from polyolefins, alone or in a mixture, said polyolefins being selected from the group consisting of low density linear polyethylene, low density polyethylene, high density polyethylene and polypropylene.

25. A process according to claim 23 or 24, characterised in that a masterbatch or batch is produced containing 20-80% by weight, relative to the total weight, of treated filler.

26. A process according to claim 25, characterised in that a masterbatch or batch is produced containing 45-60% by weight, relative to the total weight, of treated filler.

27. A process according to claim 26, characterised in that a masterbatch or batch is produced containing 50% by weight of treated filler relative to the total weight.

28. A method according to claim 23 or 24, characterized in that said polymer is expressed in the form of a film and in that said film is subjected to mono-or biaxial stretching or orientation.

29. Films, characterized in that they are obtained with a process according to any one of claims 23 to 28, in an unstretched state, or in a mono-or biaxially stretched state.

30. Films according to claim 29, characterized in that they have a mottle index of less than 10, measured according to the method known as "mottle viewer" method.

31. Articles, characterized in that they contain at least one film according to claim 30.

32. Masterbatch or batch of polyolefin and filler, characterized in that they are obtained according to the implementation of the process of claim 25.

33. Masterbatch or batch of polyolefin and filler according to claim 32, characterized in that they have a melt volume-flow rate MVR of more than 9cm³10min, measured according to ISO 1133 at a temperature of 190 ℃, a load of 5 kg and a die diameter of 2.095 mm; and they have a high thermal stability, i.e. according to a process known as the decolorization processThe length of the non-faded bars indicates a thermal stability of greater than or equal to 20 cm.

34. Use of a masterbatch according to claim 32 or 33 in the manufacture of a so-called breathable film.

35. Process for the manufacture of so-called polyolefin "breathable" films according to claim 23 or 24, characterized in that the filler is a filler according to claim 20 and the masterbatch is a masterbatch according to claim 33.

36. Polyolefin articles containing at least one filler according to any of claims 18 to 20.

37. Use of the film of claim 29 or 30 or the article of claim 36 in any industrial sector where a filler is required to have hydrophobic properties.