DE3128677A1 - METHOD FOR THE PRODUCTION OF FILMS OR PLATES THAT INCLUDE ARE SUITABLE FOR DISCONNECTING BATTERIES FROM SULFURIC ACID ACCUMULATORS. - Google Patents

Description

PATENT LAWYERS

dr. V. SCHMIED-KOWARZiK · dr. P. WEINHOLD ■ Munich DIPL ..- INO. G ^ DANNENBERC} · dr. D. GUDEL · dipl-inc. S. SCH U BERT-Frankfurt

SIEGFRIEDSTRASSE ΘΟΟΟ MUNICH

PHONE! (089) 335024 + 335025 TELEX: 5215679

SK / SK

FE.2889

Montedison S.p.A. Foro Buonaparte Milan / Italy

Process for the production of foils or plates, which are used, among other things, as Ti partition walls for batteries of sulfuric acid accumulators are suitable

O IAOO / /

The present invention relates to a method for producing films or sheets with high ion permeability and small-diameter pores used as a partition wall for batteries of sulfuric acid storage batteries can be turned.

. It is known that such battery partitions are microporous Elements between plates of opposite polarity

.10 can be inserted. These partitions must provide effective electrical insulation, good ion conductivity and contribute to the general good mechanical resistance of the structure.

On the basis of the above considerations, it is necessary that the partition walls consist of materials with excellent resistance to sulfuric acid and oxidizing agents such as PbO ₂ , do not release organic acids or chlorine and provide satisfactory electrical insulation in order to prevent short circuits between plates To prevent polarity. In addition, they must also have good ion permeability in order to allow electrolyte exchange. "

Next, it is very important that the partition walls have a very have high total porosity and that the pores at the same time have the 'smallest possible average diameter in of the order of only a few microns to prevent extremely small particles from migrating through eiα gradually reduce their conductivity and cause an undesired discharge.

The partition walls commonly used for batteries currently consist of cellulose cards impregnated with 20 to 40% phenolic resin, or of micro-foamed PVC sheets. They are provided with vertical ribs (spacers), the main purpose of which is that of metal particles that

Detach themselves from the plates during operation of the accumulators and fall into the lower part of the accumulator can.

New partitions have recently been developed based on the use of large quantities (60 to 80 %) of synthetic fibrils with a large surface area mixed with cellulose (40 to 20 %) . These fibrils,., Which preferably consist of high-density polyethylene, can, however, also be polypropylene nitriles, and are melted in the film by heat treatment at a temperature a few degrees above the melting point. This process causes a strong structural modification of the fibrils themselves. Their surface area, which is initially very high (from 1 to

more than 10 m / g), drops to 0, and wettability goes lost. In order to avoid this last-mentioned disadvantage, the mixture intended for the production of the partition walls usually larger or smaller amounts of special surfactants are added to the partitions as well after melting the synthetic component a very give good wettability. These new types of partitions have an average pore diameter from 20 to 30 microns, which is below that of normal partitions, and their overall porosity is slightly higher than that from usual partitions. Your resistance to sulfur acidity is clear that of cellulose-based partitions, superior (the latter tending to become brittle over time); this is an extension of the allows average battery life, but these partitions have the disadvantage of less to be firm.

It has now been found that you can use foils or plates for Used as partitions in batteries of sulfuric acid accumulators are suitable, pores of a very small diameter, a high overall porosity and a satisfactory Ion permeability can be obtained by

IZ.UU / /

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highly refined mixtures of cellulose fibers with olefinic polymer fibrils with a surface area of at least 1 m / g and inorganic mineral fillers made of powders that are particularly resistant to sulfuric acid are used for their production. .Lien this material show particularly after a residence time in 3O-9oiger sulfuric acid at 71 ⁰ C for 72 hours, a solubility of below 5 wt -.%.

In these mixtures is the weight ratio of Cellulose fibers to polyolefinic fibrils between 20:80 and. 40:60. The degree of refinement of these blends is between 40 ° and 75 ° shopper bar (SR). The pens is are in amounts between 20 to 55 wt .-%, based on the Total weight of the film or sheet, present.

These foils or plates are produced in the manner customary for the production of paper, starting from a dispersion of the mixture loaded with the fillers in water using customary papermaking machines.

In order to improve the water wettability of the finished product, it is advantageous to use the aqueous dispersion To add a wetting agent to fibrils and the fillers mentioned, which can be ionic or non-ionic, namely, in amounts between 0.01 and 0.3% by weight of the dry product, based on the total weight of the solids present in the dispersion.

After their formation, the wet films or sheets are pressed and then dried. The drying may be followed, for example, the * of the paper machine can be carried out on rollers before winding a dry pressing. The dry weight of the board is preferably between 100 and 250 g / m ² , while its density is between 0.35 and 0.6 g / cm ⁵ .

* on. the machine smoother (calendering machine)

CrO * ι

• * Ad ο »ο

-7-

Then the plate or film dried in this way is subjected to a solidification or consolidation process, which in addition to increasing their dimensional stability also their causes special resistance to moisture. This The process consists in heating the sheet or foil to a temperature at least equal to the melting point of the Polymer that forms the high surface area fibrils in the plate around at least a portion of it Melting polymers.

This heating occurs in the practical absence of Pressure on the plate or foil and can be carried out by passing them over the surface of a heated cylinder or into a hot air tunnel or with IR radiation irradiated. In any case, the The pressure applied to the film or plate did not exceed 0.01 kg / cm when heating by passing the foil through takes place between a pair of rollers. ' .

According to the invention has further been found ,, that avoid the above-mentioned heat treatment and yet can erzielön same effect of dimensional stability and moisture resistance of the plates, with the further advantage is that the formation of pores having small ¹ Diameter favored and a higher total porosity is obtained if a certain amount of a synthetic polymer in the dispersed state or in the form of a latex is added to the aqueous dispersion of fibers and fillers used for the production of the films, belonging to the class of vinyl or vinylidene polymers, ethylene / propylene copolymers and copolymers of vinylr or vinylidene monomers with ethylene containing copolymerized ethylene up to 50 mol%.

Such a polymer can then be coagulated by acidification in the aqueous fiber dispersion before the film is formed will.

The amount of polymer to be added to the aqueous dispersion of fibers and fillers is between 0 and 50% by weight, based on the dry polymer on a weight basis of the solids present in the dispersion. The polymer will preferably added in an amount between 10 and 20% by weight based on the weight of these solids.

Further, it was found according to the invention, that films may be obtained having good hardness in spite of the high filler content, when poly of the fiber output dispersion also.The the fillers mentioned above, and possible "mentioned above includes mers, glass fibers in an amount up to 50 wt. - %, preferably between 10 and 20% by weight, based on the weight of the mixture of cellulose fibers and polyolefinic fibrils in the dispersion, The glass fibers used for this purpose have, as an essential characteristic, a diameter not exceeding 15 microns and their length is not critical, although this is preferably between 1 »5 and 12 mm.

The aim of the present invention is therefore to provide a process for the production of foils or plates, which are used as partition walls for batteries of sulfuric acid accumulators can be used, which includes the following stages:

(I) Production of a film with a dry weight of 100 to 250 g / m 2, starting from an aqueous dispersion the end:

(a) a mixture of cellulose barrels and fibrils of at least one olefinic polymer with an upper

2 '/

area of at least 1 η / g · in a weight ratio of cellulose fibers. to polyolefinic fibrils between 20:80 and 40:60, the mixture having been refined to a value between 40 ° and 75 ° SR is;

. (b) 20 to 55% by weight, based on the weight of the solids present in the dispersion, of a powdery material of the inorganic mineral type, characterized in that this material has a solubility in 30% strength sulfuric acid at a temperature of 71 ⁰ C and, after a residence time in this acid of 72 hours, below 5% by weight ;.

(c) 0 to 50 wt .-%, based on the weight of the under (a) ■ defined fiber mixture, of glass fibers with · a Diameter not more than 15 "eaea pm;

(d) 0 to 50 wt -%, based on the weight of solids in the dispersion. a polymer in dispersed form from the group of vinyl or vinylidene polymers, ethylene / propylene copolymers and copolymers of vinyl or vinylidene monomers with ethylene with an ethylene content of up to 50 mol-Jij ■

(e) 0.01 to 0.3% by weight , based on the weight of the solids present in the dispersion, of a wetting agent, (II) drying the film or plate and, if the dispersion is not the polymer mentioned under (d) , heating the film or plate in the practical absence of pressure to a temperature at least equal to the melting temperature of the olefinic polymer forming the fibrils in order to melt at least a portion of these fibrils.

The films or plates obtained by step (I) can consist of only one layer or of a multitude of layers of different composition and according to the be produced in the usual processes in papermaking, starting from aqueous dispersions of the composition defined above.

After drying and / or heat treatment of the films or Plates according to stage (II) can be provided with the necessary spacers, e.g. by filaments from a thermoplastic polymers with suitable dimensions extruded directly onto their surface. .

When the films or sheets are subjected to a heat treatment to melt the polyolefinic fibrils contained therein may have been subjected to the attachment of the spacers take place during the heat treatment mentioned above, by, for example, filaments made of low-density polyethylene containing fillers such as talc and carbon black according to the process the Italian patent application 22,799 A / 79 of the same applicant is welded to its surface by heat.

Partition walls in the form of small pockets or sleeves can be used if "with those produced by the process according to the invention Foils or plates obtained by hot welding of the edges.

Inorganic materials that show the above-defined solubility in sulfuric acid and in the aqueous fiber dispersion can be used with which the films or sheets are produced are, for example, silica and Talc. A silica available under the trademark "Ultrasil VN-2" has proven to be particularly useful Degussa company proved. The particle size distribution or size of these inorganic materials is usually in the range below 30, preferably between 0.02 and 20 microns.

The polymers as defined under (d) are then in the fiber dispersion is mixed in in the form of an aqueous solution or a latex. Such suitable polymers are e.g. polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, polystyrene, polyvinylidene chloride, polyacrylic acid or Polymethacrylic acid methyl, ethyl, propyl, isopropyl, butyl and isobutyl esters, polyacrylonitrile, copolymers of the acrylic and methacrylic esters mentioned with acrylonitrile, acrylic acid or methacrylic acid, acrylamide or mixtures thereof, ethylene copolymers with the vinyl and / or vinylidene monomers corresponding to the vinyl or vinylidene polymers and ethylene / propylene copolymers mentioned with a content of copolymerized ethylene up to

ί I 25

: 30

30 Mol-Jß.

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The fibrils of olefinic polymers with a surface area of at least 1 m / g are products that are used in technology as a partial or complete replacement for cellulose in the manufacture of paper and similar products are known. They can be produced by various processes, such as those described in GB PS 868 651, 891 943, 891, .945 ,. 1,355,912 and 1,355,913 in U.S. Patent 3 770 856, 3 750 383 and 3 808 091, in FR-PS 2 176 858 in German patent application 2 343 543 and in IT PS 947 919 and 1 030 809. These fibrils generally have a length between about 1 and 10 mm, an average diameter between 1 and 50 Micron; according to the invention, they can incorporate inorganic fillers such as talc, kaolin, silica, titanium dioxide Barium sulfate in amounts up to 60 wt .- # ■, .- based on the Total weight of filled fibrils.

Olefinic polymers from which the above fibrils can be obtained are, for example, high and low density polyethylene, polypropylene, which predominantly consists of isotactic Consists of macromolecules, poly-4-methylpentene-i, the ethylene / propylene copolymers and blends of these polymers and copolymers.

The possible heat treatment of the foil or plate according to Step (II) to melt at least part of these Fibrils are expediently carried out at a temperature which is at least 5 to 10 ° C. above the melting temperature of the polymer i constituent or - if these fibrils consist of J consist of different polymers or mixtures of the same - of the polymer with the lowest melting temperature. J

35

• B * ·

When the film or sheet is made from dispersions containing a latex of the polymers described above, it is desirable to avoid heat-melting treatment of the fibrils. In such a case it is in fact sufficient to dry the film or plate at a temperature usually between 60 and 115 ° C in order to obtain the advantages of the presence of such a polymer in the film.
10

As cellulose fiber ^ one can use the fiber types commonly used in the manufacture of ordinary paper or similar products, preferably used mixtures of cellulose fibers from conifers and

Latifoliae. '. . ·

The following examples illustrate the present invention.

example ±

A mixture of 24.5 kg polyethylene fibrils with high density (melting temperature 135 ° C) and with a surface area of 6 m / gm, an average length "of 3 mm and an average!"

μνη

licher diameter) of 16 - ε-o as 1.0.5 kg cellulose fibers of Bianchita conifera in water- became in one

[conical refining plant at a concentration of

2.5 wt% up to 74 ° S.R. refined. Then this one

j Mixture 10 kg of glass fibers with a diameter of about

·! . Micron and a length of 6 mm and 40 kg of silica

• j3o ("Ultrasil VN-2») added.

After homogenization, the mixture was then " diluted with water" to a solids content of 0.6 % by weight

30 kg of "DR-1465" (50 wt .- # ig: er latex from a Tetra-35 polymer from butyl acrylate, styrene, a methyl derivative \ from methacrylamide and methacrylic acid, manufactured by Montedison S ^ pA) and 2 kg "Teepol PG" (anionic

It q φ fr * * * -

f Ö t> β 3d α «» «

«.Fr I) It * -Λ» ** ·.

surface-active agent from Shall) added. The dispersion was then acidified to pH 4.5 with a saturated aluminum sulfate solution and then further diluted to 0.2% by weight. A film was then produced from such a dispersion on a continuous papermaking machine equipped with a wet press3 operating at a pressure of 5.5 kg / cm. This gave a film which, after drying at about 90 ^° C., had a spec. Weight of 160.5 g / m showed. Their other properties were as follows
thickness

spec. Density. · Load at break when dry

"" Wet "residual strength when wet Bendtsen porosity i: i air maximum pore diameter average pore diameter

0.306 mm 0.525 g / cm ³ 84.54 kg / cm ² 23.30 kg / cm ² 27.56 % 35

5.5 ioro x 4.1

cm / min

electrical resistance after immersion in the bath for 20 min

Total porosity surface area stiffness

example

1.52 milliohms / dm ² .68%
12 m ^;
88 g / cm

12 m ² / g

The preparation of Example 1 was repeated, except that the film was added before being wound up in the wet press glazed at a pressure of 5.5 cg / cm. The properties the slide were as follows:;

Weight thickness spec. Dense breaking load when dry

"" Wet "residual strength when wet Bendtsen porosity ■ maximum pore diameter in air average Pore diameter

162.3 g / m ^z 0.277 mm 0.586 g / cnr 94.11 kg / cm ² 24.08 kg / cm ² 25.59 % 20

4.0 - .- / i-m 3.2 m / 4 m

cm / min

electrical resistance after immersion in the bath for 20 minutes, total porosity stiffness

Example

1.55 milliohms / dm '65 %
80 g / cm

The production was carried out as in Example 1, but with No latex used and the film in one print

of 5.5 kg / cm was glazed, then dried and ^{heat-treated in the absence of pressure at 175 0} C in order to melt at least part of the polyethylene fibrils present.

The film showed the following properties:

Weight thickness spec. Dense breaking load when dry

"" wet "

residual strength when wet Bendtsen porosity in air maximum pore diameter average Pore diameter

electrical resistance after immersion in the bath for 20 minutes, total porosity stiffness

example

159.7 g / m ² 0.267 mm 0.577 g / cm ³ 95.39 kg / cm ² 52.17 kg / cm ² 54.69 % 35 cm ^ min 4.9 3.7

2.1 milliohm / dm ⁴ 60 %
81 g / cm

An aqueous mixture of 32 kg high. · Dense polyethylene. fibrils according to Example 1 and 14 kg of bleached coniferous cellulose was at a concentration in a conical ^! Refining plant refined up to 70 ° SR. 54 kg of silica ("Ultrasil VN-2") were added to the mixture thus obtained, and the mixture was then diluted to 0.6% by weight with water.

Then 4 kg of "Teepol PG" were added, the pH was adjusted to 5 with aluminum sulfate, and the Suspension was with a continuous pressure of the

2
Naßpre.sse of 2 kg / cm processed into a film. To :

the drying was heated in the absence of pressure at 175 ⁰ C in order to melt at least a portion of the synthetic fibrils. The properties of the film obtained

were as follows:

weight

thickness

density

B'endtsen porosity in thin air maximum pore diameter avg. Pore diameter

171.7 g / m ² 0.410 mm 0.419 g / cm ³ 190 cm '/ min 10 6.7 ρ

• electrical resistance after being immersed in the bath for 20 minutes.

Total porosity
stiffness

1.45 milliohms / dm 65 %
89 g / cm

example

An aqueous mixture of 27 kg of polyethylene fibrils according to Example 1 and 12 kg of bleached coniferous cellulose was refined in a conical refining device at a concentration of 2.5 % up to 70 ° SR * 47 kg of silica ("Ultrasil VN-2 Then 28 kg latex of an acrylic copolymer ("DR-1465" from Montedison according to Example 1) and 2 kg "Teepol PG" were added. After acidification with aluminum sulfate to pH 4 , 5, a film was produced from this dispersion, which had been further diluted to 0.2% by weight, in a continuous wet press under a pressure of 3 kg / cm, which was then dried at about 95 ° C. The properties of dry

30 slides were as follows:

Weight 174.3 g / m ²

Thickness 0.390 mm

Density 0.447 g / cm ³

45 cm ^ min

Bendtsen porosity in air 35 maximum pore diameter avg. Pore diameter

6.2 n 4.1 Miei »e»

I Δ. \ J \ J I I

electrical resistance after 20 min immersion in the bath total por o sity example 6

1.3 milliohms / dm ² 67%

Starting from 25 kg of fibrils and 11 kg of cellulose fibers such as in example 5 a mixture was prepared. After refining on. 70 ° S «R. 9 kg of glass fibers were added to the mixture

• around . with a diameter of 10 and a length of 6 mm and then 41 kg of silica ("ültrasil VN-2") were added. After the dispersion had been diluted to 0.6 % with water, 28 kg of latex of the acrylic polymer ("DR-1465" from Montedison according to Example 1) and 2 kg of "Teepol PG" were further added.

The dispersion was brought to pH 4.5 with a saturated aluminum sulfate solution. Then, at a final concentration the dispensing of 0.2% produced a film on a wet press under a pressure of 5 »5 kg / cm, their properties after drying. about 95 ° C were as follows:. '. "' '■ -

Weight Thickness Density Bendtsen porosity in air maximum pore diameter average Pore diameter

electrical resistance after being immersed in the bath for 20 minutes

Total porosity B e is ρ ie 1 7 -

167 g / πΤ 0.346 mm 0.483 g / cm ⁵ 50 cm / min

6.4

4.5 ·

1.17 milliohms / dm '60 %

In a conical refining plant, an aqueous mixture with 2.5 % dry matter was refined from 43 kg of polyethylene fibrils according to Example 1 and 19 kg of bleached coniferous cellulose to 67 ° SR. This mixture was diluted to a concentration of 0.6 % , and 22.5 kg of white talc powder and 31 µg latex of the acrylic copolymer "DR-1465" used in Example 1 were added. To

ο * a «S *

Adding 2.75 kg of "Teepol PG" to the dispersion was the pH brought to 4.5 with a saturated aluminum sulfate solution.

The film was produced on the wet press of a continuous machine at a pressure of 1 kg / cm. The dry film properties were as follows: Weight "** - ^A ~ ²

163 g
0.310 mm 0.525 g / cm ³ 20 cm / min 5.6 - f * 4.0 / 4

Thick, dense Bendtsen porosity in air maximum pore diameter average pore diameter

electrical resistance after immersion in bath 2 for 20 minutes, C

Total porosity 65 %

■ Example

The preparation of Example 7 was carried out using Repeated "Ultrasil VN-2" silica instead of the talc powder. The product obtained showed the following

Properties: 'Weight Thickness Density Bendtsen porosity in air maximum pore diameter through Pore diameter

154 g / nr 0.330 mm 0.468 g / cm x ⁵ 45 cm / min 5.4 / Am-4.2-yum

electrical resistance after immersion in the bath for 20 min. Total porosity Example

1.05 milliohms / dm ² 70%.

An aqueous mixture of 24.5 kg of polyethylene fibrils according to Example 1, but with an incorporated silica content of 30 %, and 10.5 kg of coniferous cellulose was brought to 70 ° SR.

After diluting the fiber dispersion to 0.6 % your

/ Jim

17.35 kg glass fibers of 10 x diameter and 6 mm length were added, then immediately 32.65 kg "Ultrasil VN-2" silica and 30 kg latex of the acrylic polymer used in Example 1 with 50 % solids content were added. After adding 2 kg of "Teepol PG", the dispersion was acidified to pH 4.5 with an aluminum sulfate solution. The mixture was diluted to 0.2% and used to produce a film which, after drying, exhibited the following properties:
weight
thickness
density

Bendtsen porosity in air maximum pore diameter avg. Pore diameter

158.9 g / nr 0.404 mm
0.393 g / cm ³ 260 cm ^ min 11.3 8.4 / *

electrical resistance after immersion in the bath for 20 min

Total porosity example "JiO

1.39 milliohms / dm "61 %.

The preparation of Example 1 was repeated, but using 30 kg of polyvinyl chloride latex ("Diofan 193d" from BASF) as the polymeric latex. The properties achieved showed only a slight increase in the electrical resistance of the film, namely a value of 1.65 milliohms / dm ² .

example

11

The preparation of Example 1 was repeated again, However, the fibrils being polypropylene fibrils with a specific surface area of 2 m / g, an average Fibril length of 3 mm and an average

° μη
borrowed diameters of 18 e were used. The .

The properties found were practically the same as those of the films or sheets produced according to Example 1 Except for a density of 0.5 g / cnr and a specific surface area of 6 m / g.

- vr -49-

example

12th

In order to increase the production speed due to the low values of the water excretion ability of the mixtures of the preceding examples "is limited, A panel for partition walls was made using a continuous three flat machine Tables. The flat tables of the continuous machine were coated with a fiber dispersion of the same composition, charged as the dispersion of Example 1. In the plate produced in this way, the outer layers showed a spec. Weight of 50 g / m, while the inner layer has a spec. Had a weight of 60 g / m. The properties of the product obtained showed essentially the same values as in the film produced in Example 1 with the exception of the spec. Density (increased to 0.540 g / cnr) and the porosity in

Air (reduced to 28 cnr / min).

The. Manufacturing costs were compared to the machine with

reduced by 15% in only one molding table. Be is ρ ie 1 15

Using a continuous machine with three tables, a panel for partitions was made, made up of three layers with the following composition

duration:

Polyethylene fibrils according to example 1 bleached cellulose Glass fibers according to Example 1 "Ultrasil VN-2» silica Acrylic copolymer according to Example 1 ("DR-1465") in the dry state

Outside Inside layer layer 35.5 % 15.0 % 12.9 % 8.5% 8.6 % 11.0 % 21.5 % 56.0 %

21.5 %

9.5

The spec. The weight of the individual layers was around 53.5 g / m. Working in this way resulted in better retention of the filler (silica) in the plate, which increased from 88 % to 93 % . The properties of the j plate were practically the same as those of the plate j according to Example 1 with the exception of the electrical resistance; of 1.4 milliohms / dm. |

Some of the sheets or plates made in the above examples were used to make complete partitions used by providing them with spacers according to the direct extrusion process described above.

If the plates had been subjected to a heat treatment to melt the fibrils, they were attached the spacer by heat welding the latter in place during the heat treatment. In In each case, the spacers were made of low-density polyethylene with a heavy load of talcum powder, and small amounts of soot.

With the plates obtained in Examples 4, 5, 7 and 13 Furthermore, envelopes were produced taking advantage of the heat-weldability. The liability was greater in all cases than the tear strength of the material.

Claims (5)

P a t e nt a η s ρ τ u c h e - Process for the production of foils or plates which can be used, inter alia, as partitions ' luv batteries of sulfuric acid accumulators, characterized in that (I) a foil or plate which in the dry state has a spec. Weight between 100 and 250 g / m produces, whereby one of an aqueous dispersion consisting of (A) a mixture of cellulose fibers with FibrilLen of at least one olefinic polymer with a spec Surface area; of at least 1 m / g in a weight ratio from cellulose fibers to polyolefinic FibrilLen between 20:80 and 40s60, the mixture is refined to an SR value between 40 ° and 75 °, (b) 20 to 55 wt .-%, based on the weight of solids in the dispersion, a powdery material is one inorganic mineral "the strength in 30- $ sulfuric acid at a temperature of 71 ⁰ C and after a 'Vern residence time in . the acid of 72 hours, a solubility of less than ¹ wt J ■ -% has; (c) 0 to 50 % by weight, based on the weight of the fiber mixture defined under (a), of glass fibers with a diameter not exceeding 15 microns; (d) 0 to 50 wt .-%, based on the weight of the solids contained in the dispersion, of a polymer of the class of vinyl or vinylidene polymers, ethylene / propylene copolymers and copolymers of vinyl or vinylidene monomers and ethylene with a content Bn copolymerized. Ethylene up to 50 mol% in dispersed form; (e) 0.01 to 0.3 wt .- ^, based on the punched in the Solids contained in the dispersion, a wetting agent goes out and (II) the film or plate dries, and - if the dispersion contains no polymer defined under Cd) -. the foil or plate in the practical absence of Pressure heated to a temperature that is at least equal the melting temperature of the olefinic polymer forming the fibrils is so at least a part of this Fibrils to melt. 2.- The method according to claim 1, characterized in that the under (d) defined polymer in an amount between 10 and 20 weight percent based on the weight of the solids present in the dispersion. . 3.- The method according to claim 1 and 2, characterized in that that the glass fibers in the film or plate in an amount between 10 and 20 wt .-? £, based on the weight ■ ίο der.Mixture of cellulose fibers and polyolefinic fibrils in the dispersion. 4. Method according to one of the preceding claims 1 to 3, characterized in that the film or plate consists of at least two layers of different composition consists. 5.-The use of the prepared according to claim 1-4 Materials for making bags or covers. The patent attorney: ¹ 25