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Publication numberUS3661700 A
Publication typeGrant
Publication dateMay 9, 1972
Filing dateMar 18, 1970
Priority dateMar 20, 1969
Also published asDE2012636A1
Publication numberUS 3661700 A, US 3661700A, US-A-3661700, US3661700 A, US3661700A
InventorsGianfranco Zilio
Original AssigneeMontedison Spa
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Coated reinforced paper and process for preparing same
US 3661700 A
Abstract
Coated reinforced papers having excellent mechanical and other characteristics are obtained by coating a net-like support obtained from a longitudinally oriented film of polypropylene consisting essentially of isotactic polypropylene with a composition formed of cellulosic or other fibers, mineral and/or organic fillers and/or pigments, and binders.
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Description  (OCR text may contain errors)

0 United States Patent 1 51 3,661,700 Zilio 1 May 9, 1972 [S4] COATED REINFORCED PAPER AND [56] References Cited PROCESS FOR PREPARING SAME UNITED STATES PATENTS [72] In entor: Gi nfr n Zlli Mil n. I ly 3,l29,466 4/1964 LHommedieu ..l62/l08 x [73] Assignee: Montecatinl Edison S.p.A., Milan, Italy 2'148'490 2/1939 Mmspaugh 100,436 3/1870 Newton l62/l08 {22] Filed: Mar. 18, 1970 [21] App.- No: 20,846 Primary Examiner-Howard R, Caine Attorney-P. Q. Peake and Stevens, Davis, Miller & Mosher [30] Foreign Application Priority Data [57] ABSTRACT 1969 "14323 Coated reinforced papers having excellent mechanical and other characteristics are obtained by coating a net-like sup- [52] US. Cl ..l62/l03, 162/i04, ll6622//ll0284, p obtained from a longitudinally oriented m of polypropylene consisting essentially of isotactic (5 1] Int. Cl. ..B32b 5/20, D21d 3/00 r [58] Field oiSearch ..l62/103, 104, I08, 124 pdypmpylenc other fibers, mineral and/or organic fillers and/or pigments, and binders.

8 Claims, No Drawings THE PRIOR ART It is known to reinforce paper by coating it with compositions based on mineral pigments and binders, or by mixing the mineral pigments and binders with the cellulosic fibers before the paper is formed.

In general, the mineral pigments used include kaolin, titaniurn dioxide, talc, zinc sulphide, lithopone, calcium and magnesium oxides and carbonates, barium sulphate, and the like.

Binders used include, in general, natural, animal or vegetable glues or synthetic glues, in particular casein, gelatines and the like.

In order to obtain coated papers having particularly glossy surfaces, waxes and soaps, such as, for instance, camauba wax, paraffins and the like, have been included in the coatings.

It is also known to prepare papers, wholly or partially, from synthetic fibers. For instance, in patents and patent applications originating with our group there are described papers and fibrous paper-like structures consisting of cellulosic fibers reinforced by very short fibers of a propylene polymer having a fine count.

THE PRESENT INVENTION One object of this invention was to provide a new coated paper adapted to a variety of uses, and having excellent resistance to stresses of different kinds, such as to tearing, wetting, bursting and so on.

This and other objects of the invention are accomplished by this invention in accordance with which a composition consisting of cellulosic and/or other fibers, mineral and/or organic fillers, and binders is coated onto a support comprising a special fibrous polypropylenic material which is net-like and obtained from a longitudinally oriented film of polypropylene consisting essentially of isotactic macromolecules and having, preferably, a melt index comprised between 0.5 and 20.

The supports can be prepared by starting with a polypropylene film, which may be a blown film, orienting it in the longitudinal direction, and then converting it to a net-like structure. One preferred method for effecting the conversion consists in cutting up the oriented film, by means of rollers fitted with staggered pins. The rollers can be ofthe type specified in the published Japanese Patent Application of M. Niwa No. 22,048/64, filed May 15, I962. The cutting up of the oriented polypropylene film can also be effected by means of other processes and devices ofa similar kind. The oriented polypropylene film may be of any desired thickness as long as it can be converted in a net like structure; convenient thickness have been been found to be comprised between 0.001 and 0.4 mm for many uses, and preferably between 0.01 and 0.25 mm.

In the net-like structures which are particularly suitable for use in practicing this invention, the meshes of the net have sides which measure from 0.1 to 3.0 cm.

As indicated, the coating applied to the net-like structures to obtain the reinforced paper of the invention is formed of a conventional composition which is a mixture of cellulosic and/or other fibers, with mineral and/or organic pigments or fillers, and binding agents.

The coating is applied to the net-like polypropylene support by conventional devices, followed by drying and calandering of the coated support.

The following examples are given to illustrate the invention and are not intended to be limiting.

EXAMPLE I A. Preparation of support A support having a net-like structure was prepared by extruding polypropylene consisting essentially of isotactic polypropylene melt index, 2; residual ash content, 0.00l percent; residue of extraction with n-heptane, 97 percent), to form a film, stretching the film in the longitudinal direction, and cutting up the film longitudinally by means of a roller fitted with staggered pins, to produce a net the meshes of which have sides of 0.2 cm.

B. Preparation of the coating A coating paste was prepared by mixing together: 5

sulphite cellulose 3 barium sulphate 2 casein 0. water 50 C. Preparation of the paper Using conventional equipment, the coating paste was ap plied to both faces of the polypropylene net.

Thereupon the coated support was dried and calandered (with a resting time on the calender of 5 seconds and a temperature of the calander rollers of l$5 C).

D. Characteristics weight (g./sq.m.)

longitudinal breaking load (kg./sq.mm.) longitudinal elongation at break resistance to longitudinal tearing (g./2$p.) bursting pressure (kg./sq.cm.)

EXAMPLE 2 A. Preparation of the support A support having a net-like structure was prepared by extruding polypropylene consisting essentially of isotactic polypropylene melt index 2; residual ash content 0.00l percent; residue of extraction with n-heptane, 97 percent), to obtain a film, stretching the film longitudinally, and cutting up 30 the stretched film in a longitudinal direction by means of a roller fitted with pins arranged in a staggered position, such as to produce a net the meshes of which have sides of0.4 cm.

B. Preparation of the coating A coating paste was prepared by mixing together:

sulphite cellulose 2.8 kg. kaolin 2.2 kg. gelatine 0.5 kg. water 50 l.

teristics:

weight (g./sq.mt) l00 longitudinal breaking load (kg/mm) 1.4 longitudinal elongation at break (9%) 22 longitudinal tear resistance (g./25y.) 25

bursting pressure (kg./sq.cm.) 1.5

EXAMPLE 3 A. Preparation of the support A support with a net-like structure was prepared by extruding polypropylene consisting essentially of isotactic polypropylene melt index, 0.5; residual ash content, 0.00l percent; residue of extraction with n'heptane, 97 percent) to obtain a film, by then subjecting the film to a longitudinal stretching, and finally by cutting up the film in a longitudinal direction by means of rollers fitted with staggered pins such as to produce a net the meshes of which have sides of 0.25 cm.

B. Preparation of the coating There was prepared a coating paste by admixing the following substances:

sulphite cellulose 3.l kg. lithopone [.9 kg. gelatine 0.5 kg. water 50 l.

C. Preparation of the coated paper The support, consisting of the polypropylene net-structure, was coated with the coating paste by means of a conveyor belt permitting application of the coating to both faces of the support. Thereafter, the treated support was dried and then passed through a calander with a resting time in the calander of 5 seconds, and temperature of the calander-rollers of 155 C.

D. Characteristics The coated paper thus obtained showed the following characteristics:

weight (g./sq.m.)

longitudinal breaking load (kg/mm!) longitudinal elongation at break (5%) longitudinal tearing resistance [g./25p.) bursting pressure (kg./sq.cm.)

The coating applied to the polypropylene net may contain fibers different from cellulosic fibers, in whole or in part. Artificial or synthetic fibers can be used, including viscose fibers and fibers of propylene homopolymers and copolymers such as fibers of heteroblock copolymers the macromolecules of which are made up of blocks of propylene units and blocks of units of other monomers. particularly ethylene and/or butenel.

Polypropylene consisting essentially of isotactic polypropylene, that is of polypropylene made up of macromolecules having substantially isotactic structure, is disclosed in Natta et al. US. Pat. No. 3,112,300.

As will be apparent, changes in details may be made in practicing this invention without departing from its spirit. There fore, we indent to include in the scope of the appended claims all modifications which will be obvious to those skilled in the art from the description and working examples given herein.

What is claimed is:

l. Coated paper and similar fibrous structures consisting of a net obtained from a longitudinally oriented film of polypropylene and a coating on the net formed of a mixture of cellulosic fibers, at least one member selected from the group consisting of organic and mineral fillers and pigments, and at least one binder.

2. Coated paper and similar fibrous structures according to claim 1, characterized in that the net is obtained from a film of polypropylene consisting essentially of isotactic polypropylene and having a melt index of from 0.5 to 20, the net having meshes the sides of which are of the same or different length offrom 0.1 to 3.0 cm.

3. Coated paper and similar fibrous structures according to claim 2, and further characterized in that the net is obtained from a blown film of polypropylene.

4. Coated paper and similar fibrous structures according to claim 2, further characterized in that the coating contains natural, artificial and synthetic fibers.

5. Coated paper and similar fibrous structures according to claim 2, further characterized in that the binder in the coating is at least one member selected from the group consisting of natural, animal, vegetable and synthetic glues.

6. Coated paper and similar fibrous structures according to claim 5, further characterized in that the binder is at least one member selected from the group consisting of casein and gelatine.

7. A process for preparing coated paper and similar fibrous structures which comprises applying, to both faces of a supporting net obtained from a longitudinally oriented film of polypropylene consisting essentially of isotactic polypropylene, a coating consisting of cellulosic fibers, at least one member selected from the group consisting of mineral and organic fillers and pigments, and at least one binder, drying the coated net, and passing it through a heated calander.

8. The process according to claim 7, characterized in that the calander is maintained at a temperature of from about C to about C.

* I I i

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US100436 *Mar 1, 1870 Improvement in the manufacture of combined cloth and paper fabric
US2148490 *Apr 25, 1936Feb 28, 1939Sandusky Foundry & Machine ComMethod of manufacturing reinforced paper
US3129466 *Sep 19, 1958Apr 21, 1964Johnson & JohnsonReinforced nonwoven fabrics and methods and apparatus of making the same
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3880706 *Aug 29, 1973Apr 29, 1975Williams Harold Malcolm GordonSecurity paper containing fused thermoplastic material distributed in a regular pattern
US5449200 *Oct 19, 1993Sep 12, 1995Domtar, Inc.Security paper with color mark
EP0393254A1 *Apr 19, 1989Oct 24, 1990Vendor Holding B.V.A packet of toweling for single use adapted to be dispensed for hand drying
Classifications
U.S. Classification162/103, 162/124, 162/104, 162/108
International ClassificationD21H19/52, D21H13/14, C08J7/04
Cooperative ClassificationC08J2323/12, D21H13/14, C08J7/047, C08J2489/00, D21H19/52
European ClassificationC08J7/04L, D21H19/52, D21H13/14