The present invention relates to a new paper material with improved mechanical and chemical proper¬ ties, said material containing both paper fibers and textile fibers. Flexible sheet materials of textile fibers are strong, but expensive and therefore not suited for disposible coverings. Paper is on the other hand in¬ expensive, but lacks the draping properties and feel of textile material and has poor mechanical properties, i.e. poor tensile and tear strength, especially when produced in thin sheets.

The purpose of the present invention is to achieve a new flexible sheet material, which combines the feel and strength of textile material with the low price of paper.

It has now been surprisingly found out that a material which is both inexpensive and strong can be obtained by combining paper and textile material. The combination can be achieved by a composite structure of textile-reinforced paper, which is produced by wet- or dry-laying.

The material according to the invention is in¬ expensive at the same time as it has good mechanical properties by virture of reinforcement with yarn. The paper functions as a carrier, as a filler and absorbent material and as a stabilizer, which preserves an other¬ wise instable textile thread structure. The reinforce¬ ment can suitably be a fabric with a primarily tricot- knitted structure, providing the yarn structure with a zigzag appearance on one side and an essentially parallel thread pattern on the other side. Usable types of yarn which have been tried are for example 167 dtex textured polyester yarn, 9^0 dtex polyester and nylon filament yarn, 360 dtex split fiber yarn, 9^0 dtex polypropylene filament yarn and 100/150 dtex melt fiber

yarn. Possible structures are for example fringe, tricot and combinations thereof. The possibilities for reinforcement and yarn type selection for weft inser¬ tion in this production technique are extensive. The material according to the invention can be used for example as: Coating substrate For manufacture of materials for

- protective clothing - tarpaulins

- tents

- roofing paper

- wall coverings

- roller blinds Hospital and hygiene articles

- diaper covers

- operation coats

- bandages Other products - wall coverings

- wiping cloths

- filter media

- packaging material.

In the following, examples of material will be described which have been manufactured and tests done on some of the materials. Reference will be made to the drawings of which Fig 1 shows different structures used and Figs 2 and 3 show stress-strain diagrams for a composite material according to the invention. In the following description and claims the abbreviations PA, PES, PP- and PVC designate polyamide, polyester, polypropylene and polyvinyl chloride, respectively. When a plastic-coated product is mention¬ ed, it refers to a product which is either painted or laminated with plastic. The machine used for producing the test materials was bought from Karl Mayes Textil- maschinen GmbH, Obersthausen, West Germany, and is of

the Raschel type designated RS 4 MSU-V-N. The Raschel machine has four guide bars, needles of two-component type and is provided with a paper feed. Three beams (with the possibility of installing a fourth) provide the hole needles on the guide bars with yarn. The guide bars are controlled separately by a control chain and can be moved behind the needles in the desired number of steps, providing a so-called guide sequence. The outer guide bar, No 1, was used for the main structure and guide bar No 2 for the reinforcing yarn, which is laid in the machine direction. In order to provide reinforcement transverse to the machine direction, the machine is provided with a device for weft insertion. From a free-standing yarn stand, on which 48 yarn spools can be placed, 24 yarns are guided via indivi¬ dually controlled IRO-suppliers to a guide machine which places the weft threads between fork bands which transport the weft threads so that they are moved in • parallel to the needles (the knitting location). The warp och weft inserts (the reinforcements) are there¬ after bound by the main yarn which forms stitches after the needles have penetrated the fed-in paper. The machine has a knitting width of I960 mm. The machine has been rebuilt to a spacing of 9 needles/ inch since the original 18 spacing proved to be too close. The change gave good results, both as regards the product and in yarn savings. An air-formed paper

2 of 72 g/m was used as a basic material, and the reinforcement both longitudinally and transversely to the machine consisted of 940 dtex multifila ent PES- yarn. The main yarn, which binds the two reinforcing yarns to the paper, consisted of 167 dtex textured PES.

A tricot structure was used. 30 m of fabric was knitted with this structure with each of 14 different reinfor- cing variants. 5 m of each structure was glued together with an extender fabric to a length of 100 m which was then laminated with plastic both on one side and on

both sides. These materials can be considered to be suited to production of tarpaulins and rain clothing, for wall coverings in wet rooms, for example.

The machine was converted once more to a spacing of 4 1/2 needles/inch. The products had a completely different appearance and better porosity. With this . machine spacing, fabric was manufactured in many diffe¬ rent combinations. The structure, a combination of fringe and tricot, further accentuated the porosity of the fabric.

Various papers have been used. Twelve paper

2 materials with weights of between 35 and 150 g/m were used.

The reinforcing yarns varied from 40 dtex up to 940 dtex. Yarns of PA, PES and PP were used, both untextured and textured. Tests have also been done with split fiber yarns as reinforcement.

The basic material of both dry- and wet-formed ^* paper was primarily fed-in as single sheets, but tests have been performed with 2- and 8-sheet paper. Inser¬ tion of loose material between two tissue layers was also performed. Paper weights used range from 35-150

2 and 8x64 g/m .

The paper fed into the machine is given a completely changed character relative to the originally fed-in material, both in feel and appearance.

Table I - Paper used as base for the composite products

B dry-laid latex-bounded paper c wet-laid paper containing viscose rayon fibers

D 70% paper, 30% viscose

E paper fibers, viscose, PP melt-bounded

F 65% paper, 35 viscose, binder

G multi-sheet paper

The number of types of structures which can be used is essentially unlimited, both separately to each

guide bar and in combinations between the guide bars. The structures affect the final products so that both a wave-square pattern as well as a smooth surface can be obtained. The changes in appearance can be further accentuated by using yarns with special characteris¬ tics, for example shrink yarns.

Two main structures have been used: A open fringe, B tricot. The structure B was used in producing materials 1, 14 and 19. The structure C is a combina- tion of A and B.

A series of composite materials with 14 reinfor¬ cement variants was made, 1-14. In the main structure on the front beam, 167 dtex textured polyester yarn was used in all cases. This was combined with reinforcing yarns of different fineness, type and density.

Furthermore, 11 different composite materials were made, where the basic_ materials, the reinforcing materials and the' reinforcement density was varied.

Table 2 - Summary of prepared combinations of paper products, structures, spacings and reinforcements

Paper Struc- Spacing Composite Reinforcement combi¬ ture N.p.i. product combinations nation No. A

B B 9 1-14 1 2 3 4 5

2/1 2/2 2/4 2/8 4/2

6 7 8 9 10

4/2 4/4 4/8 8/1 8/2

11 12 13 14

8/4 8/8 16/8 16/12

C 4 1/2 15-18 14 1/2 15 16 17 18 1/1 1/2 1/4 1/8 1/4

C C 4 1/2 20 20 1/4

B 9 19 19

8/2

D C 4 1/2 21 21_

1/2 F C 4 1/2 22-24 22_ 23_ 24_

1/2 1/1 1/1 G C 4 1/2 25 25_

1/2

* Close reinforcement (roofing paper) ** Reinforcement transverse to the machine direction is 360 dtex split fiber

*** Reinforcement transverse to the machine direction is 940 dtex PA (roofing paper)

Tests of properties have been made on composite materials, where the carrier material is dry-laid paper reinforced with warp knit and produced on a Raschel machine. *The paper was reinforced with PES yarn (167 dtex textured), single bar tricot structure, needle ' density 9 needles/inch. The stitch density was about 3,5 stitches/cm. PA yarn (940 dtex 60 Z) was laid-in in the warp and weft directions with varying density. The reinforcement thus consisted of three thread systems. The material had a pronounced paper side and a pronounced yarn side. This carrier material had also been coated to make the material usable for ready made clothing purposes (rain clothes, protective clothing - coated on one side) and truck covers, lighter tarpaulins - coated on two sides. The coating material was plasticized PVC.

14 different qualities were produced for coating.

The goal of the coating tests was that the weight of the final product, coated on one side, would

2 be about 300-400 g/m and for material coated on two

2 sides about 500-600 g/m , (the weight of the

2 composite material was about 150 g/m ).

When producing the single-coated and double- coated products, a laminating process was used, whereby

2 a PVC-sheet (weight approximately 250 g/m ) was laid on the reinforced paper. The single-coated quality was laid on the yarn side to prevent the reinforcing threads from unravelling.

The water-repellent properties of the single- coated product proved to be poor due to the thin coating. The coating did not cover the crossing points of the 940 dtex threads. The water-repellent properties of the double-coated product were, however, completely satisfactory. For certain qualities of single-coated material, the paper was treated with the hydrophobisi- zing agent SCOTCHGUARD FC 326, which was sprayed on the uncoated side. The weight increase was about 1% .

Since the coating proved to be too thin, an additional application of various qualities of acrylic enamel was made. This enamel was used primarily for coated articles intended for ready-made clothing or furnishing (for example car seat covers). The purpose of the treatment is to provide a softer article.

2

Approximately 25 g/m of acrylic enamel was applied to the coated surface of qualities Nos 7 and 12. By PVC-coating of the reinforced cellulose material, the loosely and sparsely connected thread system was fixed. The paper makes coating possible.

The following methods of measurement were used: a) Definition of material: weight per unit area SS 25 12 69 thickness SS 25 12 65 b) Mechanical properties: tensile strength SS 25 12 67 tear strength TEFO-method 33-73 flexural rigidity SIS 65 00 43 draping BS 5058:1973

c) Other properties: adhesion TEFO-method 36-74 air permeability SIS 65 00 16- water resistance SIS 65 00 10 water tightness SIS 65 00 06 fire resistance SIS 65 00 82 wear FSD 3282 water absorption SIS 25 12 28

In the following tables of results 3-11, the uncoated qualities are only indicated by the quality number. Single-coated products have the letter B i-n front of the quality number. Double-coated products are designated DB+No. The distance between the 940 dtex reinforcement threads is for quality 2 5 mm

7 10 mm

12 . 20 mm and the same,in both directions for these qualities.

Table 3 - Weight by area, g/m2

Q u a 1 i t y

2 7 12

Only paper 77 77 77

Uncoated reinforced product 131 116 108 Single-coated product 285 370 350 Double-coated product 500 650

When coating, it is usually necessary to run about 100 m of the carrier material through the coating machine to achieve the desired coating weight, In this test, quality 2 was at the beginning of the process before the coating weight became stabilized, which explains the lower total weight per area.

Table 4 - Thickness, mm

12

Only paper 0,43 0,43 0,43

Uncoated reinforced product 0,70 0,64 0,70 Single-coated product 0,54 0,58 0,59 Double-coated product 0,62 0,77

The variation width for the uncoated reinforced qualities (14) was 0,62-0,78 mm. -

Table 5 - Tensile strength (N/cm)

Quality Warp Weft paper 2,8 2,2 uncoated reinforced product:

2 ^• 118 91

7 85,6 65,4

12 58,4 27 coated product:

B2 123 97,8

B7 72,4 52

B12 60 27

DB7 109 62

DB12 93 40

The tear strength was only determined for three qualities of coated products. The tear strength cannot be determined for uncoated materials.

Quali -ty Warp Weft

B2 defect tearing 475 N

B7 It tt 275 N

B12 tt tt 160 N

DB7 M tt 225 N

DB12 tt tt 150 N

10

Table 6 - Flexural rigidity (Nm 10-51

Quality Warp Weft paper 1,3 1,0 uncoated reinforced product:

2 2,0 1,5

7 1,5 0,9

12 1,2 Q,9 coated product:

B2 11,2 3,9

B7 12,9 4,4

B12 13,7 3,5

DB7 31,0 10,8

DB12 30,2 18,8

Table 7 - Draping, %

Quality paper 66,5 uncoated reinforced product:

2 64 ^{' "} " 58

12 58 coated product:

B2 70,5

B7 67,5 B12 65

DB7 82

DB12 84

Adhesion, air permeability, water resistance, water tightness, fire resistance and wear were tested for the coated materials only.

Table 8 - Adhesion (ace, to TEFO-method 36-74), N/cm Quality A-A B-B DB8 10 5

A-A = yarn side against yarn side B-B = paper side against paper side

Table 9 - Air P'ermeιabjLI: tty

Quality cc/s liter/min

B2 0,3 0,015

B7 0,06 0,01

B12 0,06-5 0

Gl 42

G2 0,05

Notes: Gl and G2 are Gore-Tex materials Gl - weight 208 g/m ² G2 - weight 316 g/m

Since the water resistance of the single-coated product was quite poor, tests were done with hydro- phobisizing and extra coating.

Table 10 - Water tightness, cm water column

^Q uality _ __ ^* <=

B7 ^• 14 15,5 B12 16 17,5

Gl 11 11

G2 100 100

1 = 1st drop 2 = 4th drop

Notes: B7 and B12 are treated with Scotchguard.

For the double-coated product the water column was 2 ml

Table 11 - Water resistance

Quality % absorbed water

B7 not hydrophobisized 60

B7 hydrophobisized 5

B7 enamelled 6l B12 not hydrophobisized 66

B12 hydrophobisized 2,1

B12 enamelled 59

The coated product burns but not any more readily than any other coated textile with no flame¬ proof finish.

Wear was tested on DB12 (double-coated product) according to defence standard FSD 3282 Taber Abraser, wear disc CS-10 load 250 g.

After 1500 revolutions no break through was detected.

The test shows that the PVC-coated reinforced papers produced have a good tear strength relative to the tensile strength. The tear strength of 160-475 N for the single-coated qualities B2-B12 is high in comparison with common materials for protective and rain clothing, which usually have a tear strength of at most 100 N.

These -new materials have a lower flexural rigi¬ dity (i.e. are softer) and have better draping proper¬ ties than conventionally produced cpated products.

Tests with asphalt coating of two materials were made with good results to form "roofing paper".

^" The possibility of using textile reinforced paper as wiping cloths has been investigated. For this purpose samples were produced containing 1, 2, 3 and 4 layers of basic material made of paper and rayon fibers. Two different polyester yarns were used as reinforcing threads in the samples. The absorption rate, maximum water absorption and strength in wet state were measured for these materials.

"Wiping cloths"

Table 12 - Breaking force and breaking extension in dry and wet state

Not reinforced Textile reinforced

Dry Wet Dry Wet N/cm % N/cm % N/cm % N/cm %

DL 8,2 10 5,6 20 19,0 26 17,8 27

WL 11,2 25 3,2 10 20,0 26 17,2 29

DL = dry-laid paper WL = wet-laid paper Reinforcing thread 167 dtex PES

Table 13 - Maximum water absorption ace to SIS 25 12 28 (for textile reinforced and non-reinforced paper) No. of Dry weight Wet weight Water absorption ^• layers G G ^■ % at equilibrium of paper A B A B A B_

1 0,55 0,44 3,25 2,1 591 466

2 0,97 0,91 4,97 4,25 514 467

3 1,47 1,31 6,85 5,95 466 453

4 1,94 1,78 8,62 8,1 446 454

A = textile reinforced B = not reinforced

There are two properties which might need improvement in the new materials. They are the ^* water resistance of the single-coated product (for the double-coated product it was good) and the adhesion of the double-coated product.

In order to make the single-coated qualities (intended for ready-made clothing) water-resistant, the paper must be hydrophobisized. The extra enamel applied was of no use in this context. An additional step should be calendering the carrier material, enabling a smoother surface to be coated. The adhesion of the double-coated product was poorest on the paper side. This could be a result of the fact that the paper cohesion was poor or that the adhesion between the PES- threads and the PVC-paper was too low. In the former case, it can be remedied by adding SBR-latex to the paper, and in the latter case by other common adhesives of isocyanate type.

Hydrophobisizing and latex treatment can be carried out in connection with calendering of the carrier material.

For tarpaulins, the weight is usually about 700 g/m . The double-coated product in this test had a weight of between 600 and 650 g/m .

The tensile strength is determined by the heavy

PA-reinforcement <940 dtex threads) and should not be significantly affected by the coating. The differences can depend on the fact that the carrier material shrinks when coated and that the reinforcement is so sparse that it has a great effect on the tensile strength values measured according to the strips method. The flexural rigidity of the single-coated product was in the range of about 11-13 Nm 10 , which is at the level of coated knitted material for rain clothing (a-bout ^' 10) and bett'er than for coated woven material (about- 20) for ^* the same purpose. The flexural rigidity of the double-coated product is much lower than what is normal for tarpaulin products. The drape is good for these coated papers and is better than the average for comparable materials on the market. The tear strength of the reinforced product is affected by the density of the textile reinforcement. The tear strength increases significantly even for very sparse textile reinforcement. The tear strength is at the level of coated flexible sheet material for ready-made products.

In summary, it can be said that the materials produced have good tear strength relative to the tensile strength, good draping properties and low flexural rigidity, good wear resistance and poor adhesion. The water resistance is good for the double- coated product and satisfactory for the single-coated product, if the paper has been hydrophobisized. The

untreated material has good absorption of liquids, for example water and oil, and good wet strength.

By virtue of the- present invention, paper can be used at the same time as expensive textile fibers are saved. In this way, inexpensive disposible products with improved hang and mechanical properties can be obtained. Sheet material according to the invention is also suited to be used as a substrate for plastic- or rubber-coating. All types of textile fibers, both in woven and knitted state, can be used, and especially synthetic fibers.