JP3005345B2 - PEEK hot pressed felt and fabric - Google Patents

Abstract

The present invention relates to a fabric for a paper making machine which fabric comprises a woven substrate carrying batt fibre on the surface thereof characterised in that at least one of the batt fibre and the substrate comprises a polyetherketone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber and a fabric used for press felt used in a high temperature environment.

[0002]

2. Description of the Related Art Recent proposals in the papermaking art have disclosed that dewatering of paper sheets in the press section of a paper machine results in very high dry values when the press section is heated to a temperature above the boiling point of water. are doing. This method is generally used for impulse drying.
is called. The best results, ie the highest sheet drying, are obtained at press roll temperatures above 150 ° C.
The application of such impulse drying to conventional commercial paper machines, typically including roll presses and shoe presses, results in a more energy efficient process and improved paper quality. The difficulty with such a proposal is that the fabric normally used to convey the paper sheet through the press and assist in dewatering the sheet requires the combination of high temperature and mechanical pressure currently proposed for impulse drying as shown above. That is, I can't stand it well.

[0003] Commercial pressed fabrics generally consist of synthetic polyamide fibers. These materials have excellent impact, abrasion, and hydrolytic stability and provide excellent life in commercial operation at temperatures between ambient and about 80 ° C. However, at temperatures above the above, conventional polyamide fabrics fuse into compressed chunks that are not useful for dewatering the paper sheet.

The emergence of a new technology for high temperature dewatering involves the formation of fibers that do not deform or lose quality when exposed to high temperatures and mechanical pressure and that maintain useful dewatering properties over the life of the press fabric. Requires pre-fabric.

[0005] Many high temperature fibers have recently been developed that require use in space exploration and industrial processes. Representative fibers are materials from the comprehensive class of polyaramids, polybenzimidazoles, polyetherimides, polysulfones, polyphenylene sulfides, and polyarylates. While all of these materials have high temperature serviceability, most do not have suitable physical properties useful for use for pressed fabrics. Many materials, such as polysulfones and polyetherimides, are amorphous materials that tend to deform under load at temperatures above their glass transition temperature and undergo irreversible deformation through repeated press nips. receive. Other materials, such as polyaramids, polybenzimidazoles, and polyarylates, are semi-crystalline polymers, but are generally highly aromatic, hard materials that are pressed after relatively few compression cycles. Subject to brittle fracture in the nip.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a fabric used in a papermaking dewatering step, which is suitable for use under high temperature and mechanical pressure.

[0007]

SUMMARY OF THE INVENTION Surprisingly, we
Polyetherketones have been found to be semi-crystalline and highly aromatic, but do not exhibit brittle fracture at normal or elevated temperatures when manufactured to have a particular fiber structure.

Therefore, according to the present invention, a bat (ba)
tt) A fabric for a paper machine, comprising a woven, knitted, braided or non-woven base having fibers, wherein at least one of the bat fibers and the base comprises polyetherketone. I do.

[0009] The present invention also provides a method for providing a paper-making component and dewatering the feed to produce a coherent sheet.
Introducing the feed into a dewatering device, followed by pressing at an elevated temperature, wherein the paper is transported by a continuous fabric, the method comprising pressing the sheet in at least a portion of the process. It is characterized in that the drying is carried out at 100 ° C. or higher, and furthermore, at least the part of the fabric has a bat fiber on its surface, and is made of a woven, knitted, braided or non-woven fabric base material. Also included is a method for making paper, characterized in that at least one of the batt fibers and the substrate is comprised of polyetherketone.

In a specific embodiment of the present invention, the polyetherketone is polyetherketone, polyetherketone (PEK), polyetheretherketone (P
EEK), polyetherketoneketone (PEKK), and polyetheretherketoneketone (PEEKK)
A fabric selected from one or more of the following.

In another aspect of the invention, the polyetherketone may include an effective proportion of an antioxidant. The fibers used in the present invention are trade names "Victrex P"
Manufactured from commercially available polyetherketones, such as those commercially available under the trademark "EK" or "Victrex PEEK", both of which are currently available from ICI,
Although primarily intended as injection molded materials, they can be formed into fine fibers or monofilaments.

In another aspect of the invention, the polyether ketones retain a relatively lower fabric surface temperature after passing through a heated press environment than the other materials evaluated, while at the same time forming a sheet. Improves desorption characteristics. At high fabric temperatures (near the lignin tack point), the paper sheet tends to stick to the pressed fabric, making sheet detachment difficult. Generally, a cold pressed fabric surface facilitates sheet detachment.

[0013] For press fabrics, the polymer molecular weight is preferably high, and the optimum properties in molding and retention of molecular weight during subsequent use are obtained by mixing a proportion of antioxidant with the resin prior to molding. Was found. Typical antioxidants suitable for use in the present invention are phenolic antioxidants and / or antioxidants based on α-tocopherol.

In a further aspect of the invention, the fiber morphology of the PEEK fibers for impulse drying is medium (mo).
requires that the fiber be moderately drawn with orientation and crystallinity and not be extremely low or high in orientation or crystallization, thus providing excellent mechanical properties for impulse drying I found that. Fibers with low or high orientation and crystallinity result in more rapid undesirable mechanical failures, such as planarization and fibrillation. In a preferred aspect of the invention, the orientation and crystallinity are between 30 and 75%, preferably between 40 and 70%, between the low and high extremes of each of these properties.
It is in.

In another aspect of the invention, the crystallinity of the polyetherketone is in the range of 50-65% of the extremes of crystallinity of the polyetherketone used.

In another aspect of the invention, the polyether ketone is PEEK fiber and has a viscosity of 0.20 g
It has a contraction force of d or less.

In another aspect of the present invention, polyether ketones having at least one yield point of 3.0 gpd or less are used.

The following is an embodiment.

[0019]

EXAMPLE 1 A polyetheretherketone resin commercially available from ICI under the name Victrex PEEK 380G, hereinafter referred to as PEEK-a, is extruded by a standard melt extrusion spinning process and yields about 17 denier per filament. Of the multifilament yarn. The fibers made had medium orientation and medium crystallinity. The fibers were crimped and cut into 3 inch staples. The properties of the resulting fiber were 3.1 g / den tenacity, 31% elongation at break, and 26
g / dens initial modulus (intia1 m
odus). The fiber is made into a web by using a card, and a needle (ne
edle). In order to evaluate the fiber performance of the press fabric, a test was performed in a press section of a test machine. For comparison, PM
Card web samples of conventional polyamide fibers commonly used for C, and PBI polybenzimidazole, Ryto
n polyphenylene sulfide, Nomex polyamide,
Samples of representative high temperature fibers such as and Kevler polyaramid were needled into the same test fabric. The fabric was tested under the following conditions.

Speed-1000 m / min Linear pressure-100 KN / m Felt tension-3 KN / m Suction vaccum-40 kPa Water temperature-60-65 ° C Total compression number -10⁶  Total experiment time-265 hr

A sample of each fiber is 10 ⁵ , 2 × 10
⁵ , 3 × 10 ⁵ , 4 × 10 ⁵ , 5 × 10 ⁵ , 7.5 × 1
Removed after 0 ⁵ and 10 ⁶ compression cycles. PE
The EK fiber works equally well with the best commercial polyamide fibers, but other high temperature fibers are found to be significantly damaged (planarization and fibrillation), 2 × 10 ⁵ and 3 ×.
After ¹⁰⁵ cycles is determined that no longer perform its function.

Example 2 Two samples of commercially available PEEK resin were made into staple fibers and finally into carded vats for evaluation on test press fabrics (Example 1).
As described in). One of the fiber samples was PEEK-a described in Example 1 and the other fiber sample, referred to as PEEK-h, was an 80 mm staple length crimped fifteen dtex fiber manufactured by a Hoechstactien Gesell shaft. Both PEEK-a and PEEK-h have the same molecular weight but differ in fiber morphology. The PEEK-h fiber has the following properties, as shown by DSC, DMA and shrinkage studies:
It has a higher level of orientation and crystallinity.

Each layer of PEEK fiber was needled in another area on the surface of the test press fabric. The fabric was tested on a test press under the following wet press conditions.

Machine speed: 1000 m / min Linear pressure: 100 KN / m Fabric tension: 3 KN / m Suction vacuum: 40 kPa Water spray temperature: 64-72 ° C. Total compression number: 1,000,000

The test results are shown in FIGS. 1 and 2 of the accompanying drawings. FIG. 1 is a photomicrograph of PEEK-h. It can be seen that the fibers are significantly flattened and fibrillated. As a result, the dewatering capacity of this sample is significantly impaired. In contrast to the sample of PEEK-a shown in FIG. 2 after ¹⁰⁶ compressed in much better condition. The fiber has undergone some flattening, but the fiber remains intact,
The dehydration properties of the structure remain intact. Thus P
EEK-h fibers are flattened and fibrillated to unacceptably high levels. The performance ranking given to each fiber is shown below. It should be noted that small numbers on a scale of 1-5 indicate better performance, and a ranking difference of 0.5 is significant.

PEEK-a ranking-3.3 PEEK-h ranking-4.8

The results of the erratic study are shown in the table below. DS
C 1st heating cycle data shows that both endothermic melting temperature and endothermic peak area PEEK-
h indicates that it is high. DMA result is PEEK-h
The tan delta maximum temperature is higher at lower values than PEEK-a, indicating a higher level of orientation. E 'value (storage modulus) is Tg or more and P
Higher for PEEK-h fibers than for EEK-a fibers,
This also supports higher orientation in PEEK-h fibers. E 'values for both fibers were reported at two temperatures. The selected temperature is the highest tan delta temperature for each fiber,
Corresponds to 182 ° C and 193 ° C. The shrink force data further confirms the higher orientation and crystallinity of the PEEK-h fibers. The shrinkage value is PEEK-h from PEEK-a fiber.
Regardless, it is great without contradiction. 8 shows the data of the contraction force at 80 ° C. and 150 ° C. 80 ° C. indicates the temperature of the water used in current wet pressing technology, and a temperature of 150 ° C. indicates the temperature for typical impulse drying.

[0028]

[Table 1]

Example 3 Referring to FIGS. 3 and 4 of the accompanying drawings, a sample PEEK-a was used.
And the difference in form between PEEK-h and PEEK-h will be described.

FIG. 3 is a graph in which the abscissa indicates the temperature expressed in ° C. and the abscissa indicates the contraction force measured in grams / denyl (gpd). The low orientation property of the sample PEEK-a can be clearly understood from the lower contraction force curve as compared with PEEK-h. The lower crystallinity of the PEEK-a sample can be seen in FIG. 4 where the elongation% is plotted on the horizontal axis and the specific stress as applied force expressed in gpd on the vertical axis. The curve for more crystalline PEEK-h is smooth, while the curve for sample PEEK-a shows many distinct yield points as indicated by the steep and abrupt changes in slope on the curve. See, for example, A and B.

Example 4 A needled nonwoven was prepared by needled together a continuous card web layer of the same PEEK fiber as described in Example 1.
Each butt weighing about 120 g / m ²
t) was cross-wrapped at a 90 ° angle before needling. All fabric products consisted of 8 batt layers and weighed about 1000 g / m ² . The same fabric was made from commercial polyamide 6,6 fibers, representative of the fibers used in commercial paper machine crossing fabrics. Each fabric is available from Lavery, H .; P. CPAA Annual Meeting Preprint, 73B: 121-
126 (January 29, 1987) was used in an experiment to dewater a 25% solids paper sheet with an impulse dryer similar to that described. The PEEK sample successfully removed moisture from the paper to a high level of drying without any apparent physical damage. The polyamide sample in the same test fused into an impermeable mass during the first impact. Holing plate (fa11ing plate)
e) The temperature is maintained at 300 ° C. and the peak pressure is 600 p.
si, and the equivalent nip stay time was 4.5 ms.

Example 5 Another PE spun from a commercially available resin
EK fiber samples were evaluated in a test impulse dryer.
This PEEK fiber, termed PEEK-i, is 13.3
It has a dtex and 80 mm fiber length, is manufactured by ICI under the trademark ZYEX, and spun into a fiber form similar to PEEK-a (medium orientation and crystallinity). PEEK-i is a multi-candid
ate) Part of the evaluation of the test fabric. Press roll temperatures as high as 205 ° C. were tried throughout the impulse drying test, at which point the PEEK-i sample had excellent temperature resistance and sheet handling with acceptable dewatering performance. Two other high temperature fibers were evaluated for comparison. An aromatic aliphatic polyamide spun from a fiber sample called fiber U13, which is a fiber spun (at AIRESCO) from Ultramid T resin grade KR4351 from BASF, and BX
C, metaphenylene insalamide (isothal)
amid). PEEK-i, U13, and BX
All C fibers were high temperature fiber materials, but fibers U13 and BXC were inferior in sheet handling. Fiber U13
And the BXC surface was very sticky and did not release the paper sheet after passing through the heated press nip.
PEEK-i had excellent sheet detachability.

Example 6 PEEK-i was evaluated on another impulse drying pilot paper machine that included a heated long nip press. PEEK-i fibers were prepared into test sized needled fabrics with a roll temperature of 202.
℃, machine speed 2000 fpm and roll pressure 67
Evaluation was performed using a 00 pl pilot machine. Throughout this test, the PEEK-i fabric had excellent sheet release properties and good dewatering performance. The surface temperature of the fabric measured throughout the test was relatively low. We believe that keeping the fabric surface temperature low is important for good sheet release. Other fibers that were tested on the same equipment and did not release the paper sheet were determined to be very tacky or to have a "hotter" fabric surface temperature. The surface temperature of the post nip fabric of PEEK-i was about 60 ° C. This was promising when compared to another fabric candidate having a sheet contact surface of polytetrafluoroethylene (PTFE) with a post nip fabric surface temperature of about 93 ° C, experiencing the problem of sheet detachment.

[Brief description of the drawings]

FIG. 1 is a photomicrograph of a sample PEEK-h fiber of Example 2.

FIG. 2 is a micrograph of a sample PEEK-a fiber of Example 2.

FIG. 3 is a plot of shrink force versus temperature for the sample of Example 2.

4 is a plot of applied stress versus percent elongation for the sample of Example 2. FIG.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Charles Edwin Cramer Metacomet Street, Walpole, Mass., United States 7 (72) Inventor Sandra Crot Barlow Blackton, Massachusetts, USA Hop Brook Lane 8 (72) Inventor Francis Devonport North Hill Drive, Ballston Lake, New York, USA 29 (56) References JP-A-1-52897 (JP, A) JP-A-63-78098 (JP, U) JP-A-62-231016 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) D01F 6/76 D21F 7/08 D21F 3/00-3/02

Claims (13)

(57) [Claims] 1. A fabric comprising a woven, knitted, braided or nonwoven-type substrate having bat fibers on its surface, wherein at least one of said bat fibers and substrate comprises polyether ketone, A fabric for a paper machine, wherein both the orientation and the crystallinity of the ketone are from 30 to 75%. 2. The fabric of claim 1, wherein the polyether ketone is selected from one or more of polyether ketone, polyether ether ketone, polyether ketone ketone, and polyether ether ketone ketone. 3. The fabric according to claim 1, wherein the polyether ketone contains an effective proportion of an antioxidant. 4. The fabric according to claim 3, wherein the antioxidant is selected from phenolic antioxidants and / or α-tocopheral. 5. The composition according to claim 1, wherein both the orientation and the crystallinity are 40 to 70.
%, The fabric according to any one of claims 1 to 4. 6. The fabric according to claim 1, wherein said quality is 50 to 65%. 7. The fabric according to claim 1, wherein the polyether ketone is a polyether ether ketone fiber having a contraction force at 150 ° C. of 0.2 gpd or less. 8. The fabric according to claim 1, wherein the polyether ketone has a tensile stress property of not more than 3.0 gpd and having one or more yield points. 9. Use of a post nip surface temperature of at least 15 degrees Celsius in the press where the sheet contact surface is lower than the temperature of a comparative fabric having a sheet contact surface of polytetrafluoroethylene when compared under the same pressing conditions. The fabric according to any one of claims 1 to 8, comprising the polyether ketone shown therein. 10. A method for feeding paper-making ingredients, introducing said feed as a layer into a dewatering position, dehydrating the feed to form a coherent sheet, and then pressing at 150 ° C. Is transported by a continuous fabric, wherein the pressing and drying of the sheet in at least a part of the process is performed at 150 ° C. or more, and the fabric in at least the part of the process is A method for producing paper, comprising a woven, knitted, braided or nonwoven-type substrate having bat fibers on its surface, wherein at least one of the bat fibers and the substrate comprises polyetherketone. . 11. The method of claim 10, wherein the fabric is in a wet press section at a dewatering location. 12. The method according to claim 10, wherein the fabric is used in a drying section of the process. 13. The fabric according to claim 2, wherein the fabric is a fabric according to claim 2.
The method according to claim 12.