AU627251B2

AU627251B2 - Paper machine felts

Info

Publication number: AU627251B2
Application number: AU46396/89A
Authority: AU
Inventors: Sandra Krohto Barlow; Robert Bernard Davis; Charles Edwin Kramer
Original assignee: Albany International Corp
Current assignee: Albany International Corp
Priority date: 1988-11-28
Filing date: 1989-11-24
Publication date: 1992-08-20
Anticipated expiration: 2009-11-24
Also published as: DK100891A; ATE96480T1; ES2045469T3; AU4639689A; DK100891D0; CA2003910A1; NO911984D0; GB8827789D0; NO178469C; JPH04507267A; DE68910285T2; NO911984L; NO178469B; FI912554A0; EP0372769B1; WO1990006397A1; BR8907793A; FI92943C; FI92943B; DE68910285D1

Abstract

The present invention relates to an article of paper machine clothing formed from a fibrous material having a woven base and an optional batt layer attached thereto characterised in that said fibrous material comprises fibres of poly( undecanoamide) (polyamide 11) formed by the extrusion of a melt of polyamide 11 having an intrinsic viscosity of at least 1.0 dl/gram.

Description

E B. RICE CO PATENT ATTORNEYS This form is suilable for any type of PItent Application. No legalisation required.

I: I; I; OPI DATE 26/06/90 APPLN. ID 46396 89 PCI AOJP DATE 26/07/90 PCT NUMBER PCT/GB89/01410 INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 5 (11) International Publication Number! WO 90/06397 D21F 7/08 Al (43) International Publication Date: 14 June 1990 (14.06.90) (21) International Application Number: PCT/GB89/01410 (81) Designated s: B D Kj, J U (22) International Filing Date: 24 November 1989 (24.11.89) Published With international search report.

Priority data: 8827789.2 28 November 1988 (28.11.88) GB Applicant (for all designated States except US): ALBANY- RESEARCH LIMITED Gl,/OB], 40/'43 Claicery L n, L,n.n WC2A 1JQ (GB) (72) Inventors; and Inventors/Applicants (for US only) DAVIS, Robert, Bernard [US/US]; 3 Lavelle Lane, Framingham, MA 01701 KRAMER, Charles, Edwin [US/US]; 7 Metacomet Street, Walpole, MA 02081 BARLOW, Sandra, Krotho [US/US]; 6 Hopbrook Lane, Blackstone, MA 01504 (US).

(74)Agents: EVANS, David, Charles et al.; F.J. Cleveland I 1A Company, 40/43 Chancery Lane, London WC2A 1JQ

(GB).

(54) Title: PT 0 (54) Title: PAPER MACHINE FELTS (57) Abstract The present invention relates to an article of paper machine clothing formed from a fibrous material having a woven base and an optional batt layer attached thereto characterised in that said fibrous material comprises fibers of poly(undecanoamide)(polyamide 11) formed by the extrusion of a melt of polyamide 11 having an intrinsic viscosity of at least 1.0 dl/gram.

l WO 90/06397 PCT/GB89/01410 PAPER MACHINE FELTS

DESCRIPTION

This invention relates to paper machine felts. In a paper making machine, a slurry of paper making constituents referred to as "furnish" is deposited on a fabric or "wire" and the liquid constituents are drawn or extracted therethrough to produce a self-cohesive sheet which is then passed to the pressing and drying sections of the paper-making machine. In the pressing section, the paper sheet is transported by a felt to a pair of rollers where the felt and paper sheet pass between the nip of the rollers to dewater and to dry the paper sheet. The paper sheet itself may contain all types of chemical finishes and will be, at the same time, subjected to an elevated temperature to aid the dewatering and drying thereof. The paper making felt together with its sheet of paper tends therefore, to be subjected to immense pressure at elevated temperatures in a rigorous chemical environment.

II

PCT/cB 8 9/ 0 14 8 OctohT In 0I -2 Paper making felts are generally produced by needling batt fibre to a woven backing which then supports the forming paper sheet as it passes through the press. In the nip of the press rolls, the batt fibres are bent and deformed under great pressure and at great frequency and hence the mechanical properties of the batt fibre are of considerable importance in these processes.

Polyamide 6 and polyamide 66 (PA 6 and PA 66,) have been used extensively in the manufacture of paper machine felts, These polymers are readily formed as fibres and their fibre characteristics can be controlled to allow production into acceptable felts. Many prior art proposals for the use of polyamide materials in sheet and felt materials in general have been proposed.

For example, in British Patent Specification No.

1304732, there is a reference to the use of polyamide such as nylon 6, nylon 66, nylon 610, nylon 67, nylon 8, nylon 9, nylon 11 and nylon 12. The specification is concerned with the manufacture of fibrous sheet materials and is not specifically concerned with paper machine clothing.

U:;-ited Ki;ngdcm al-t Oc' TceITUE PCT International Appcation SUBSTITUTE SHEE t ,ll -j 3 1 O 1 4i 3 1 8 Octob),r 1090 3 British Patent Specification No. 1329132 again relates to a known woven fabric for use, for example, as an interlining. Again, there is reference to the use of polyamide such as nylon 6, nylon 11, nylon 12 and copolyamides such as nylon 66 and copolymers of nylon 6 and nylon 66 with nylon 11 and nylon 12.

Prior British Specification No. 1585632 has been concerned with the manufacture of artificial leather and like materials and again the use of nylon 6, nylon 66, nylon 10 and nylon 11 and nylon 12 are disclosed together with various copolymers of different variations and combinations thereof.

In each of these cases, the nylon materials are used primarily for their inherent strength in a clothing or decorative assembly and would not be subjected to the agressive physical and chemical environment of a paper making machine.

European Patent Specification No. 000708 relates to a paper making machine felt comprising a woven heat set belt which in the machine and transverse direction comprises thermoplastic filaments, in which belt the -1 r SUnited Kingdom Patant Offic e SPCT International Application SUBSTITUTE SHEET PCT/GB 89 014 1 83 Ocf~rr i;";O 1 10 -4 filaments in at least one of the machine and transverse directions are co-extruded and in which monofilaments have a core of polymer selected from nylon 66, polyethylene terephthalate and tetrapolymer of tera or isophthalic acid and a sheet of copolymer selected from nylon 11, nylon 12, nylon 6, nylon 610, nylon 612, polybutylene terephthalate and a large number of other materials.

In European Patent Specification No. 0070708, the materials are being employed primarily for their well known properties of strength and abrasion resistance.

Our co-pending European Application No. 88303201.3 shows that nylon 12 can be used in the construction of a felt for use in a paper making machine. Our researchers have shown quite surprisingly, that nylon 11 has properties which compare favourably with nylon 12 although this would not have been expected from the normal structure thereof. Polyamide 11 (polyundecanoamide) referred to in this specification as "PA 11" is well known in polymer technology and as an article of commerce.

Polyamide 11 was developed commercially for sources directed primarily to injection moulding applications.

United Kinrgdom Fatent Offce PCT .Jnterna;ional .Appcatinj SUBSTITUTE SHEET 18 October 1990 18 10 ,0 The polyamide 11 homopolymer without cross-linking additives may be extruded to form a large number of items and is ideally suited to the formation of monofilaments and fine denier continuous filament yarn.

While it would not be expected that this material would provide satisfactory properties required in a paper machine batt to provide the surface properties required, the present Applicants, unexpectedly, have found that batt materials of polyamide 11 when used in paper _.achine felts have superior durability and enhance recovery from compression and resistance to fibrillation compared with felt materials currently employed. In addition there is a superior chemical resistance to hydrolysis and resistance to degradation of physical properties by hypochlorite and other oxidation and we have found surprisingly that polyamide 11 can exhibit a 50-100% greater lifetime use in particularly hostile chemical and abrasive environments in paper making.

According to one aspect of the present invention, therefore, there is provided an article of paper machine clothing formed from a woven fibrous material, characterised in that said fibrous material comprises fibres of l polyamide 11 formed by j tnied Kt-nto f SUBSTITUTE SHEET j.PCT Internatio aiApI

P

PCT/GB 8 9 0 14 1 0 1 8 October 1990 8 i0 f9, -6 the extrusion of a melt of polyamide 11 having an intrinsic viscosity of at least 1.0 dl/g.

According to a different aspect of the present invention, there is provided an article of paper machine clothing formed from a fibrous material having a woven base and a batt layer attached thereto, characterised in that the fibrous material comprises fibres po lyud wiemide polyamide 11 formed by the extrusion of a melt of polyamide 11 having an intrinsic viscosity of at least 1.0 dl/g.

In some embodiments of the present invention the melt to be extruded may contain 0.2 to 1.0% by weight of an anti-oxidant and more preferably, 0.4 to 0.7% by weight.

The anti-oxidant may be selected from one or more of alpha-tocopherol, condensation products of diphenylamine and acetone and closely related structures derived from diphenylamine and compatible phenolic stablisers with amide functionality such, for example, as that made commercially available by Ciba Geigy under the trade name "IRGANOX 1098". Polyamide fibre containing approximately 0.5 to 0.6% by weight of anti-oxidant

:I

United Kingdom Patent Office SUBSTITUTE SHEEi PCT International Application L I 18 October 1990 18 T0 7 individually and separately or in combination results in a further enhancement of durability.

Polyamide 11 resin of the appropriate instrinsic viscosity may be compounded during extrusion of monofilament or continuous filament by the addition of selected anti-oxidants. Polyamide 11 monofilanent to be incorporated into a paper machine felt produced in accordance with the invention may be extruded at temperatures across the barrel between 220 0 C and 295°C. The spinneret may be maintained at temperatures of approximately 300 0 C. Monofilament may be extruded with the drawdown of between 2.0 X and in order to provide monofilaments of 0.1 0.25 mm for manufacturing of Fourdrinier or other forming fabrics. A particular utility for improved durability against abrasion, polyamide 11 monofilament may be also used advantageously as shute filament and/or warp filament in single, double or triple layer of press fabrics.

i Surprisingly, it has been found that the incorporation of polyamide 11 high molecular weight monofilaments may be employed in Fourdrinier forming fabrics as warp or United Kingdcm Patent OffCeB

U

PCT International Application SUBSTITUTE SHEET Ti i 1Y 8 machine direction monofilaments. It is thus possible in accordance with the invention to prepare high durability all polyamide forming fabrics and avoid a mix of material presently employed in which polyamide filaments must be alternatively inserted with polyester monofilaments in the shute direction in order to provide a measure of enhanced abrasion resistance without the existence of dimensional instability which normally results from the use of polyamide 6 or polyamide 66 material.

In a preferred form of the present invention, the article of paper machine clotting will have a fibre ranking after one million compressions less than 3.6 (refer example 3 below).

The paper machine felts produced in accordance with the present invention have a low moisture regain and are relatively insensitive to physical properties in the presence of water.

S* Monofilaments may be extruded with variations in the process to deliver this and other desirable tensile 20 properties for the weaving of base materials for needled nonwovens employed in the pressing section of a paper making machine. Monofilaments in large diameters may be employed in both the warp and shute directions in dryer 25 screen applications.

w J~ierl S~ a PCT/GB /0 1 4 1 0 18 October 1990 I rTn Qo -9 Fine denier monofilaments of high molecular weight polyamide 11 may be extruded with anti-oxidant employing barrel temperatures within the range 215 0 C to 277 0 C with a spinneret temperature of approximately 270 0 C. Continuous filament yarn of appropriate denier desirable for various layers of the batt of press felts can thus be extruded and later crimped and cut into staple fibre for batt manufacture and thereafter employed as a batt layer in press felts.

The advantage of the felts produced in accordance with the present invention is that such felts have superior durability due to enhanced resistance to fibre fibrillation and recovery from compression which result in compaction resistance. In addition to these advantages there is superior chemical resistance particularly resistance to hydrolysis and resistance to degradation of physical properties by hypochlorite and other oxidation. Such fibres in press felts exhibit superior durability against abrasion damage experienced with papers containing fillers especially including clay or crushed limestone. Such felts exhibit at least 50-100% greater lifetime in use in particularly hostile chemical and abrasive i S T 'i matet lofn.02. SUBSTITUTE SHEET -fr on ar 13 Oc0iobr 19 0 C I7 0 0 9a environments. These results are quite surprising and outstanding and would not have been expected from our previous experience with incumbent polyamide materials.

Following is a description by way of example only of methods and with reference to the accompanying drawings of carrying the invention into effect:- In the drawings:- Figure 1 is a photomicrograph of a compression test of a standard PA 66 fibre used in the manufacture of a paper machine felt.

Figure 2 is a photomicrograph of a fibre in accordance with the present invention.

S I1

PCT

SUBSTITUTE SHEET WO 90/06397 PCT/GB89/0141J EXAMPLE 1 Continuous filament of PA 11 was prepared according to the following procedure. Commercially available PA 11 was purchased as pellets from Rilsan Corp., New Jersey, having an intrinsic viscosity of 1.20 dl/g when determined in concentrated sulfuric acid. These polyamide pellets were vacuum dried at 80 0 C for 16 hours to a final vacuum measured outside the vacuum oven of 140 microns Hg. The pellets were transferred in a manner so as to avoid absorption of moisture from the air to a hopper of a single screw extruder. The extruder was equipped with a 2.5 cm diameter low compression screw. The extruder was fitted with a filter pack of 55 micron nominal porosity. Downstream of the filter the extruder was fitted with a Zenith gear pump metering the melt to a spinneret. The spinneret had 30 holes, each hole of diameter 0.5 mm. The extruder had a temperature profile ranging from 243 0 C at the hopper throat to 271 0 C at the pump with 5 zones of independent temperature monitoring and control. The spinneret was maintained at 270 0 C. Filaments were 1 extruded at approximately 195ft/min with a maximum draw-down such that the radial change was approximately 7-8/1 between spinneret and the first Godet. Yarn was WO 90/06397 PCT/GB89/01410 11 taken up on a cylinder attached to a Leesona winder after the Godet.

A typical fibre as-spun according to this procedure was drawn in two stages with a third stage of relaxation all with heat to provide an overall 2.3X draw ratio. The first temperature of drawing was at 110 0

C;

relaxation occurred in the 2nd stage at 160 0

C.

Fibre from such a process was prepared to be 12.8 dpf (denier per filament). Fibre thus prepared had 4.6 gpd tenacity with an initial modulus of 26 gpd and an elongation at break of 45%. The stress-strain curve exhibited a deflection at an elongation of 10% at gpd specific stress.

Such fibre was crimped in a heated stuffer box crimper to provide continuous yarn with a variable random crimp with approximately 4 crimps/cm. It was cut into staple of approximately 7.0 cm length. Such fibre was carded, lapped and needled into a press felt to provide a batt structure at an overall batt weight of approximately 1000 g/m 2 A felt having such a batt structure exhibited at least 50% increased life in comparison to similar PA 6 felts when challenged with the same furnish on the same position on a paper machine.

i' L EPT/GB 9 0 14 1 0 18 October 1990 18 10 qO 12 EXAMPLE 2 Fibres were prepared as described in Example 1 with the following exceptions. Prior to drawing, pellets were tumbled with powdered Irganox 1098 (Ciba-Geigy) at a loading such that the blend would be 0.7% wt/wt.

Pellets appeared to be uniformly coated with the powder antioxidant prior to transfer to the hopper. UV analysis of the as-spun fibre indicated a uniform concentration in several samples tested at a concentration of approximately 0.5% wt/wt.

EXAMPLE 3 Polyamide fibres produced in accordance with Example 1 were formed into a batt structure. Comparable filaments of a standard polyamide 66 currently used as an industry standard in the manufacture of paper machine clothing and commercially available under the trade reference T-100 supplied by DuPont was formed into a similar batt. Each of the batts was then incorporated by needling to the backing of a test felt to be run on a compression test machine. The felt containing the two batt samples was installed on the test machine and the machine was run to pass the felt between a pair of nip rollers with a predetermined nip loading. The test felt i"ng oI SUBSTITUTE SHEE j t lI: 18 October 1990 _13 was run on the compression tester for one million compressions. After the one million compressions, the felt was removed and the batt examined under an electron microscope.

The results are shown in Figures 1 and 2 of the accompanying drawings. The results were assessed on a scale of 1 to 5 by inspection and comparison against prepared standards and given a ranking accordingly. The DuPont polyamide 66 was given a ranking of 4.0 on a scale of 1 to 5 in which 5 is the worst. An examination of the photomicrographs will show extensive fibrillation and fracture of the flattened filaments. By comparison examination of the polyamide 11 candidate batt shows a marked lack of fibrillation of the fibres and with only flattening and some transverse fracture of some of the fibres. It was given a ranking of 3.3 on a similar scale as above.

The candidate fibre PA 11 was, therefore, in substantially better condition after a million compressions than the industry standard. This result was a significant improvement over and above that which would have been expected for polyamide 11 filaments.

iA' Kingcfn IPatent (Tffice, j P ApplicAtion SUBSTITUTE SHEET PCT/GB 3 014 13 October 1990 14- Samples of commercial PA 66 fibre of instrinsic viscosity 1.36; commercial PA 6 fibre of instrinsic viscosity 1.46; staple fibre of Examples 1 and 2 above with fibre instrinsic viscosities of 1.05 and 1.12 respectively were each subjected to 35% hydrogen peroxide aqueous solution at pH2 and at 60 0 C for 24 hours. Retained IV results were as follows: Candidates Example 1 PA 11 Example 2 PA 11/AO PA 6 PA 66 Initial IV 1.05 1.12 1.47 1.36 Final IV 0.87 0.97 0.49 0.62 Retained 83% 87% 31% 47% 'Inittd 4Krgdcm pat,,7" U fnternatki A SUBSTITUTE SHEET

Claims

1. An article or paper machine clothing formed from a woven fibrous material characterised in that said fibrous material comprises fibres of polyamide 11 formed by the extrusion of a melt of polyamide 11 having an intrinsic viscosity of at least 1.0 dl/gram.

2. An article of paper machine clothing formed from a fibrous material having a woven vase on a batt layer attached thereto characterised in that said fibrous material comprises fibres of polyamide 11 formed by the extrusion of a melt of polyamide 11 having an intrinsic viscosity of at least 1.0 dl/g.

3. An article as claimed in claim 1 or claim 2 characterised in that the melt on extrusion contains 0.2 to 1.0% by weight of an anti-oxidant.

4. An article as claimed in any one of claims 1, 2 or 3 'i characterised in that the anti-oxidant is selected from one or more of alpha-tocopherol, condensation products of *diphenylamine and acetone, condensation products of 20 diphenylamine and compatible phenolic stabilisers with amide functionality.

An article as claimed in claim 3 or claim 4 characterised in that the anti-oxidant is present in an amount of 0.4 to 0.7% by weight. 25

6. An article of paper machine clothing as claimed in claim 2 or any one of claims 3, 4 and 5 when appended to claim 2 wherein the fibrous material has a fibre ranking i after one million compressions in the compression test herein described of less than 3.6.

7. An article of paper machine clothing as hereinbefore described with reference to any one of the examples.