JP2929297B2 - Forming cloth for paper industry - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a papermaking industry fabric made from synthetic plastic fibers.

BACKGROUND ART In a papermaking machine, a continuous sheet of paper or paper material is formed by pouring a water-based slurry of cellulose fibers into a rug belt that is conveying. Because the slurry is continuously moving on a belt, also known as a forming cloth or wire, it absorbs a large amount of the water contained in the initial slurry and transforms into a nearly self-supporting wet paper. Typical slurries delivered to the transfer molding cloth can contain about 0.5% by weight of cellulose fibers, can be at temperatures of about 30 to 85 ° C, and have a standard pH of 4 to 9. I am. The wet paper that passes the forming cloth through the press and dry sections can contain 80% by weight of water.

The wet web is passed to the press section after it has passed the wet end or past the forming section on the couch roll. Here, most of the residual moisture is removed by passing through a series of pressure dowels. As it passes the press section, the web passes through a heated drying section for final drying. Next, the dried paper web is polished to make the surface smooth, and finally wound up on a reel.

Wet slurries facilitate removal of water as it moves along the forming fabric through the use of hydrofoils, table rolls, and suction boxes.

The forming fabrics in the original Fourdrinier paper machines consisted of a structure woven of metal wires, and as a result, these forming fabrics became known as cordless papermaking wires. These cordless papermaking wires are also used in all types of paper machines and all paper types. While these cordless papermaking wires are effective, they are not without their drawbacks, especially when they contain abrasive fillers such as silica and calcium carbonate in cellulose fiber slurries. There seems to be.

Recently, these cordless papermaking wires have been replaced by molded fabrics made of synthetic plastic fibers, of which monofilaments are common. Since the final base of good quality paper depends on the forming cloth, the structure and properties of the forming cloth are particularly important. The main advantages of the synthetic fabric made of synthetic plastic monofilament over phosphor bronze wire are:
This is an improvement in abrasion resistance in which the service life is at least four times the average of a rope paper wire. However, these forming cloths remain prone to wear by the same type of fillers which causes problems with aged phosphor bronze wires. To successfully combine the forming fabric of a paper machine, it is desirable to have the following features.

(I) It has abrasion resistance due to frictional contact with mechanical parts and contact with solids in a cellulose fiber-water slurry.

(Ii) The structure of the molded fabric surface is stable and withstands stress applied during use.

(Iii) The machine is completely wet during the operation of the machine and dries when the machine is stopped for a long period of time. Therefore, even if moisture is absorbed by a wide range of moisture-absorbing components, the molded fabric surface is not changed in size.

(Iv) It is resistant to pulling even if it receives the pulling force applied by the power roller that feeds out the forming cloth in the paper machine.

(V) It should not be denatured by various substances present in the cellulose fiber-water slurry and the substances used for cleaning the molded cloth at the general use temperature.

Even existing formed fabrics, even long-lasting phosphor bronze cordless papermaking wires, do not have all these properties completely. For example,
As explained above, phosphor bronze wires do not have the required abrasion resistance. Even commercially available synthetic plastic monofilaments do not meet all the standards required by the paper industry. Synthetic polymers that are currently the most used acceptable monofilaments for the production of molded fabrics are polyesters, more specifically polyethylene terephthalate,
And polyamides, more particularly nylon-6 (polycaprolactam) and nylon-66 (polyhexamethylene adibic acid). These monofilaments have been mixed with other monofilaments such as polyethylene and polyester based on polybutylene terephthalate, but previously such cooling batteries were far from complete. In fact, the essential difference consists of two things:

(A) Polyethylene terephthalate has sufficient scientific stability and dimensional stability, is easy to weave, has good crimpability, and shows good heat setting behavior. There are many regrets about typical high-speed machines.

(B) Nylon-6 and Nylon-66 have sufficient abrasion resistance, but have very poor crimpability and insufficient heat setting behavior, so that weaving has serious drawbacks, and furthermore, it has a drawback in the papermaking environment. In the temperature range, the dimensional stability is poor and the resistance to some of the substances used for cleaning the molded cloth is not sufficient. In a humidity range such as a papermaking environment where nylon-6 and nylon-66 operate from completely wet to dry, the inherent dimensional instability limits the content ratio of nylon monofilament to polyethylene terephthalate monofilament.

This is disclosed in U.S. Patents 4,529,013 and 4,289,173.
Are mentioned in both. West German OS 2,502,466
However, it also shows a figure of 50%, and nylon filaments are at least 4% in diameter compared to polyethylene terephthalate monofilaments (recommended maximum value is
25%). For example, as described in European Patent Application No. 158,710, this question is addressed by improving the abrasion resistance of polyethylene terephthalate monofilaments while maintaining superior dimensional stability compared to nylon. Attempts to do so have not yet been fully successful. Similarly, Canadian Patent 1,23
As disclosed in 5,249, even though improving the wear resistance of nylon monofilaments, we did not do anything to reduce the dimensional instability of existing nylon, so we solved the limit of nylon monofilament content I can't. An alternative solution to the need for crimpless nylon is proposed in U.S. Pat. No. 4,709,732. However, here, the purpose is to increase the complexity of the molded cloth, not to the dimensional instability, and does not recognize an increase in the content of nylon.

As described above, in a molded cloth containing nylon and polyethylene terephthalate, an acceptable compromise can be made by limiting the amount of nylon used. Said molded fabrics appear to be resistant to the expected pH in use and may range from about 4 to 8 or 9. Polyethylene terephthalate fibers do not decompose much under these conditions, even at temperatures up to about 85 ° C found in modern paper machines.

OBJECTS OF THE INVENTION The present invention relates directly to the wet end or forming section of a paper machine, and also refers to a papermaking woven fabric known as a "formed cloth". These forming fabrics are used to remove the moisture content of the cellulose fibers at an early stage of dewatering to form a wet web.

The present invention also seeks to solve the problems associated with the use of nylon by using papermaking molding fabrics, including monofilaments based on polymer blends with the weaving and heat setting properties of polyethylene terephthalate. . This molding cloth will also take up at least the wear resistance of ordinary nylon-containing molding cloth. It is desirable to use polyethylene terephthalate monofilaments for the yarn remaining when the molded fabric is made, but the present invention uses the present polymer for the remaining molded fabric because other yarns or monofilaments are likely to be usable. It's not just about doing. Further, while the following discussion discusses the present invention by considering the monofilament as a molded fabric, it can also be used with molded fabrics woven from yarn and monofilament. The yarn used is preferably a monofilament.

EXAMPLES Accordingly, from a broad aspect, the present invention provides a forming fabric for a papermaking machine woven from:

(A) Any one of a warp and a weft woven in the primary direction, which is the first direction which is the flow direction of the forming woven fabric; (b) The secondary direction, which is the second direction which is the width direction of the forming woven fabric, for example, A set of yarns woven substantially perpendicular to the primary direction, consisting of at least 60% by weight to 90% by weight of polyethylene terephthalate and no more than 40% by weight to 10% by weight of thermoplastic polyurethane; Of a hydrolysis stabilizer.

In addition, whether the warp paper is along the flow direction of the forming woven fabric,
Alternatively, whether the forming woven fabric is along the width direction depends on the weaving method used.

That is, when the forming woven fabric is woven as a continuous continuous cloth, the warp is along the flow direction which is the longitudinal direction of the forming woven fabric, and the weft is along the width direction of the forming woven fabric.

Further, when the forming woven fabric is woven as a continuous loop by annular weaving, the weft is along the flow direction which is the longitudinal direction of the forming woven fabric, and the warp is along the width direction of the forming woven fabric.

That is, in a continuous stretch of cloth, the warp is in the flow direction as the longitudinal direction, and in the annular forming woven cloth, the warp is in the width direction.

The simplest fabric, for example, a plain weave commonly used for clothing fabrics, has a set of warps interlaced with a set of wefts. This weave is sometimes used for sagami cloth. However, in addition to this, several more complex types of cloth are used. It is well known to use two completely different sets of warps, with each set of warp weaving with one set of wefts to match the unique pattern of this warp.

Furthermore, in fabrics, each set of warps does not need to be made from the same polymer, as they are often not the same physical dimensions. As an example, one warp can be relatively thick and can be made from a wear-resistant monofilament such as the monofilament of the present invention, while the other warp can be relatively thin and
T can only be.

The thick warp contacts the support surface in the machine, while the thin PE
T support paper. 2 made of so-called binder yarn
It is well known to use two sets of warp and two sets of weft to weave as two nearly independent layers of fabric.

Such a cloth consists of five yarns, all of which can be of different sizes, and all five yarns need not be of the same polymer. Again, each set of warps and wefts is for a different purpose, one supporting the paper web and the other contacting the support surface of the machine.

This disclosure refers to references that describe the above forms of fabric construction. However, even a simple cloth having only one set of warp and weft does not require that either the warp or the weft be all the monofilament of the present invention. In other words, the yarn is incorporated by the fabric designer, giving the fabric the properties it needs to meet its application.

For the present fabric in a preferred embodiment, the yarns used in the primary and secondary directions are preferably monofilaments, and the yarns used in the primary direction are preferably polyethylene terephthalate with the remaining secondary direction yarns.

Thus, the use of the novel monofilaments of the present invention in the broadest embodiment is independent of the form of the forming fabric used. This includes single layer, two layer or double sided, and molded fabrics commonly known as composites. Additional descriptions of these common molded fabric types can be found in U.S. Patents 3,858,623 and 4,071,050, and in Canadian Patents 1,115,177.

For more specific embodiments, the invention essentially comprises
Synthetic monofilaments made from a blend of from 60% to 90% by weight of polyethylene terephthalate and from 40% to 10% by weight of a thermoplastic polyurethane, and about 5% by weight of a hydrolysis stabilizer for thermoplastic polyurethanes provide.

Preferably, the weight percentage of thermoplastic polyurethane is about 15%
And more preferably from 25% to about 35%, most preferably the amount of thermoplastic polyurethane is about 30%
It is.

For the preferred embodiment of the present forming fabric, the yarn used is a monofilament. For a further preferred embodiment, the yarns which make up the majority of the surface of the forming fabric and part of the machine side which is the back of the forming fabric are polyethylene terephthalate monofilaments.

From the following description, the term "machine direction" means that the forming fabric is essentially parallel to the direction of flow through the paper machine.
Similarly, the term "cross-sectional direction of the machine" means a direction on the forming fabric surface that is essentially perpendicular to the "machine direction".
In a molded cloth woven not as a continuous loop but rather as a regular length of the molded cloth (later joined to form a continuous loop), the "machine direction" corresponds to the warp and the "machine cross-sectional direction" Corresponds to the weft.

Thus, the molded fabric of the present invention is composed of two types of yarns, preferably one is a monofilament made of polyethylene terephthalate, and the other is a monofilament blended of polyethylene terephthalate and thermoplastic polyurethane.

Quite surprisingly, polyurethane was reduced from 10% to almost 40
% Blends provide abrasion resistance close to that of nylon monofilaments, but have been found to have no problems associated with the nylons caused by permanently impairing crimpability. In fact, certain polyethylene terephthalate-thermoplastic polyurethane blends exhibit better crimp and heatset behavior in the monofilament than do thermoplastic polyurethanes. This property is directly related to the weaving behavior of these monofilaments and is generally unpredictable. The use of the latter monofilament further simplifies the weaving structure because it provides sufficient abrasion resistance to the machine side, which is the back side of the forming cloth, without using the nylon monofilament often used in the cross-sectional direction of the machine. Is done. To suppress the dimensional instability of nylon due to the presence of water as is well known,
At best, other substitute yarns can be mixed into the weaving. Therefore, in the monofilament of the present invention, since a monofilament made of a blend of polyethylene terephthalate and thermoplastic polyurethane can be used alone as the only weft, there is no need to mix the weft.
This is because a monofilament blended with polyethylene terephthalate-thermoplastic polyurethane needs to be used only as the weft of the forming cloth on the machine side, so that the monofilament becomes a highly abraded surface. .

For blended monofilaments, there are several requirements that must be met by the polyethylene terephthalate component to provide a polymer blend with sufficient properties, as well as to provide a material that can be melt injected into the appropriate monofilament. . The molecular weight of the polyethylene terephthalate, in addition to the standard conditions of purity, no "stain" and in particular the absence of water (polyethylene terephthalate is relatively hydrophobic and contains at most 0.007% moisture) Must be the same as the resin normally used for warp and weft. Thus, the polymer must have an intrinsic viscosity in the range of 0.50 to 1.20 when measured according to the method described below. The range of the intrinsic viscosity is preferably 0.65 to 1.05. The following names (including trademarks)
The grade of polyethylene terephthalate available under the trade name has such properties.

DuPont "Merge 1934" (a Du Pont product sold under this name) Alnite A06-300 (trademark of Akzo) Vitaf 9504C (trademark of Goodyear) Tenite 10388 (trademark of Eastman) As a guide, these preferred viscosities are about From 1.5 × 10 ⁴
It corresponds to a number average molecular weight in the range of 5.2 × 10 ⁴ .

The intrinsic viscosity described below is measured with a solution in which polyethylene terephthalate is dissolved in a solvent in which phenol and (1,1,2,2) -tetrachloroethane are mixed at a weight ratio of 60:40. The measurement of the viscosity is performed at 30 ° C.

Looking at the proportion of thermoplastic polyurethane in the blend, the material used for processing into monofilaments by the usual melt injection method is essentially anhydrous, free of impurities as much as possible and free of "dirt". is necessary. Generally, there are two types of thermoplastic polyurethanes. That is, there are a polyethylene terephthalate derivative and a polyether derivative. It has been found that the use of a variant of polyethylene terephthalate is more effective and desirable for achieving the object of the present invention.

Preferably, the thermoplastic polyurethane is a relatively soft material, and the softness is measured according to the standard method described in ASTM method D.2240. The hardness should not exceed 95 when measured with an A-type durometer, or exceed 75 when measured with a D-type durometer.

The grades of thermoplastic polyurethanes available under the following names (trademarks) are suitable for the preparation of the polymer monofilament blends of the present invention.

Ester-based type: Dexin 445D (trademark of Mobay) Elastran C95 (trademark of BFSF) Peletan 2102-80AE (trademark of Dow Chemical) Ether-based type: Dexin 990A (trademark of Mobay) Peletan 2102- 80A (trademark of Dow Chemical) In the preceding description, 100% in total, mainly for simplicity
And Generally speaking, the other additions are only small amounts, and pigments such as TiO2 add up to 0.5% by weight to give the fibers the desired appearance. Certain conditions require the addition of a hydrolysis stabilizer. If the paper machine is operated below about 43 to 48 ° C., the hydrolysis of the blended monofilament in the present invention does not need to be emphasized. Many paper machines operate up to a higher temperature, 85 ° C. This is necessary because at this temperature the blended fibers would degrade faster than expected without the hydrolysis stabilizer. Although the tensile strength was affected only to some extent, abrasion resistance was found to be significantly reduced from testing, and it is believed that the thermoplastic polyurethane decomposes as shown below.

The amount of stabilizer used is from zero to a maximum of about 5% of the total weight
And further improvement is not recognized even if it is added more. When a stabilizer is used, no inhibition rate is observed below about 0.3%. Thus, it is desirable to use a stabilizer in the range of about 0.3% to 5.0%, with a more preferred range being from about 0.3% to about 3%. The stabilizer is conveniently incorporated into the blend by a "master patch" made of either thermoplastic polyurethane or polyethylene terephthalate.

Available stabilizers of the latter type which have been found to be effective include:

Starvacol KE7646 (trademark of Rain Chemie) Starvacolsol P100 (trademark of Rain Chemie) Hytrel 10MC (trademark of DuPont) Monofilaments are mixed with anti-static and anti-friction agents, for example, to facilitate handling and weaving. It is contemplated that a coat could be applied. Generally, the gradual coating is removed as soon as the formed fabric is used in a paper machine.

Examples In summary, the following abbreviations are used in the following examples: PET is used when referring to polyethylene terephthalate, and TPU is used when referring to thermoplastic polyurethane. Where necessary, TPU refers to ether-based to ester-based.

In the following example, PET is a DuPont product sold under the name "Merge 1934". Generally, this material is dried before use and can be post-condensed in a solid state to achieve an intrinsic viscosity within the specified range. Similarly, the substance TPU is dry before use. Nylon will be nylon in any case.

These examples also use monofilaments made from specialty polymers. Where relevant, the dimensions of these monofilaments are known. Generally, the monofilament used in the forming cloth has a size in the range of about 0.1 mm to about 0.9 mm, and is often used in the range of about 0.127 mm to about 0.4 mm.
mm range. It should be noted that the cross section of the monofilament need not be circular, but may be particularly square or ribbon shaped.

A. Abrasion of monofilament To know the abrasion resistance, weigh the monofilament of the strand length first and then wind it around one end of the polyethylene rod. A polyethylene terephthalate (PET) control monofilament is wrapped around the other end. Next, the polyethylene rod is attached under the vertical axis perpendicular to the polyethylene rod, and the winding is immersed in a slurry containing 57% by weight of sand of particle size 24. The shaft is rotated by a motor drive mechanism provided on the tank containing the slurry. After a set time, the strand is removed from the slurry, rewound, dried and weighed. Abrasion resistance is determined by calculating the percentage of the weight lost. To get the measurement result, select the time and the rotation speed of the shaft. After the monofilament coil is immersed in a solution whose pH and temperature are controlled to change the time, the abrasion resistance of the decomposed sample is determined by the same means.

The following results were obtained with a blend of PET-TPU with varying concentrations of TPU.

From this data, the abrasion resistance of the monofilament made from the blend of PET and TPU was slightly better than PET with 15% TPU, and the TPU concentration increased as the concentration increased to 45%. However, at a concentration of 45% TPU, monofilaments are difficult to control during injection and are too soft to be suitable for weaving and heat setting.

 The TPU used in these experiments is Dexin 445D.

The effect of the stabilizer on the degradation resistance of the blended monofilament in a pH 4.0 solution is shown in the following results.

From this data, the addition of the stabilizer to the PET-TPU blend showed a significant improvement in degradation resistance at all temperatures. The stabilizer in such a case is STABAXOL KE 7646, T
The PU was Lexin 445D.

 The effect of stabilizer concentration is shown in the following table.

Both stabilizing blends significantly improved degradation resistance, but higher concentrations of the stabilizer did not.

In these examples, the TPU was PERETANN80AE and the stabilizer was staboxil KE 7646.

In another test, the effect of stabilizer on abrasion on a blend that did not hydrolyze 65% PET and about 35% TPU was examined. The results are shown in the following table.

This data shows that the addition of the stabilizer does not adversely affect the abrasion resistance. In this experiment,
Dexin 445D for TPU and staboxil KE7 for stabilizer
464. PET used for all experiments from A1 to A19
Was DuPont Merge 1934, which was post-condensed in solid form.

B. Wear of forming cloth To determine the wear resistance of the forming cloth, the forming cloth specimen is fixed to the outer surface of the drum made of ceramic segments rotating in a horizontal plane while applying tension. . A water jet is constantly applied to the entrance nip of the forming cloth on the drum to wet the forming cloth and the ceramic surface.

The thickness of the molded fabric is measured at the start of the test and thereafter at a specified time after being applied to the surface of the rotating ceramic segment. The lost thickness is the rate of wear resistance.

One double-molded cloth sample was woven using a warp yarn having a diameter of 0.16 mm and a mesh number of 59 / cm. The machine side set, the lower or back side of the weft, was woven using a blend of PET, alternate PET / Nylon, and 75% PET / 25% PUT. The number of weft yarns was 51 / cm.

All of these specimens were 0.19 mm diameter paper side paper and 0.30 diameter
Weaved with mm machine side weft. Regarding the results of the abrasion test in which the machine side, which is the back side of
It is shown in the following table.

From these results, it was found that PET / Nylon substitute PET /
It can be seen that the formed cloth made of nylon weft and the formed cloth made of 75% PET / 25% TPU blended weft have better abrasion resistance than the formed cloth woven with PET weft. further,
Molded cloth using PET / TPU weft has better abrasion resistance than molded cloth using substitute PET / nylon.

In the second test, the abrasion resistance of a molded fabric specimen using a blended monofilament with various concentrations of PET and TPU was measured. 25 meshes on top
And the number of meshes in the lower part was 12.5 / cm.
0.11 each for upper and lower wefts of rectangular cross section
mm to 0.19 mm and 0.19 mm to 0.38 mm. In all cases, binder or tie strands of 0.14 mm PET weft were used. The lower layer of the forming cloth contacts the drum.

TPU used is Dexin 445D, PET is Dupont Merge 1934
The post-condensation was performed in the solid state of the blended monofilament.

In other words, post-condensation is a standard treatment that is often applied to polyethylene terephthalate resin before using the polyethylene terephthalate resin to make fibers, and in some cases, the producer may be required to May be applied to polyethylene terephthalate resin.

The solid polyethylene terephthalate resin is a small pellet, usually a small cylinder less than 1 centimeter in both length and diameter. Generally, polyethylene terephthalate resin in the form of pellets contains a certain amount of water, which is generated by the esterification reaction used to make polyethylene terephthalate. Also, this polyethylene terephthalate resin
It contains free hydroxyl groups and free carboxyl groups mainly at the polymer chain ends. In order to post-condense the polyethylene terephthalate resin, the resin is in a vacuum, at a temperature near the melting point of the resin, but not at a temperature near the melting point at which the pellets stick together and begin to adhere to each other.
Heat until Typically, the temperature is about 200 degrees Celsius for each grade of PET. Use a fairly high vacuum of less than about 10 mmHg.

As a result of this heat treatment, two things happen. First
In addition, the free water in the resin evaporates, thus drying the free water. Second, some degree of esterification occurs, which generates more water, which also evaporates and increases the molecular weight of the polymer, as indicated by the measured increase in inherent viscosity of the polymer. You.

The data show that the strand abrasion test findings show that the abrasion resistance of the fabric woven with the blended PET / TPU weft is better than that of the fabric woven with 100% PET weft, and that The abrasion is supported by the finding that the concentration of polyurethane increases with increasing concentration. 65% PET /
The 35% TPU specimen has better abrasion resistance than the substitute PET / Nylon-66 specimen.

C. Dimensional Stability Due to Wet and Dry Wet fabrics are often subjected to dry and wet processes. For example, after being sent to a paver mill and dried, it is saturated with water immediately after the papermaking operation of the paper machine. During the life of the molded cloth, the molded cloth may be dried out several times due to maintenance stoppages and weekends. The width of a formed cloth having a large percentage of nylon monofilaments in the cross-sectional direction of the machine varies. When PET and nylon monofilament are contained in two layers, there is a difference in the degree of expansion and contraction and the degree of contraction between the two layers. Due to such changes in the degree of expansion and contraction during the drying and wetting steps of the molded fabric, the paper volume of the nylon monofilament is limited to 50% of the fibers in the entire machine cross-sectional direction. Most molded fabrics are limited to 25% of the total. That is, 50% of the monofilament in the machine section direction on the machine side, which is the back surface, is nylon, and the remaining fibers on the machine side and the monofilament on the paper side are all PET. PET monofilaments have a nylon content of 25
%, The nylon monofilament and all molded fabrics significantly prevent expansion and contraction even at various water contents. Length measurements for the test were performed at room temperature immediately after wetting or drying.

Change in length from wet to dry (%) C1 +0.64 C2 +0.07 C3 +0.04 C4 +0.10 C5 +0.03 C6 +0.04 C7 +0.23 TPU: Dexin445D PET: DuPont Merge 1934 The results show that there is a well-known behavior between nylon and PET monofilament concentrated to an intrinsic viscosity of 1.02. It also shows that the monofilament from the blend according to the invention is very stable. Blended monofilaments begin to show dimensional instability at 45% TPU concentration.

D. Crimp The commonly used measure of crimp for the weft strands of a formed fabric is commonly referred to as differential crimp. The warp monofilaments in the final formed fabric tend to be straighter than the wefts which are bent up and down the warp slightly more easily.

Therefore, weft monofilaments tend to be superior on warp monofilaments, especially on the machine side, which is the back side of the molded fabric. However, if the weft is a very hard monofilament, the warp tends to bend, and therefore, when a very hard monofilament is used as the weft, it cannot be said that the warp is superior to the warp. By carefully measuring the thickness of the forming cloth, it is possible to measure how much the weft protrudes from the plane of the warp. Such a difference in the planes of the warp and the weft is called differential crimp. The higher the crimp of the weft monofilament, the higher the differential crimp for any woven construction.

The following table shows examples of differential crimps observed in specimens of a double-molded fabric having the same weaving structure, warp strands, number of meshes, and heat setting history in various weft strands.

It can be seen that the crimpability of the PTE-TPU monofilament is much higher than that of PET, and that the crimpability of nylon is low. PET and TPU by blending are the same as in Example E5 below.

E. Mechanical Stability The mechanical stability of the molded fabric is evaluated by measuring the elongation and the resistance to the reduction of the size.

Attach a 25.4 mm long, 50 mm wide cloth to an Intron ™ tensile tester. The load and elongation are recorded while increasing the tensile force of the specimen from zero to 7.16 kg / cm. Tension resistance is determined by measuring the slope of the load-elongation curve. It defines the elastic modulus of the fabric and ranges from about 1100 to about 2000 kg / cm for molded cloth.

For the reduction of eye resistance, the sample tensile force is reduced from zero to 7.16 kg.
The measurement is performed on the same specimen attached to the Instron, except that the decrease in width is accurately measured when increasing to / cm. The resistance reduction factor can be found by dividing the measured width change by the total tensile increase to give a percentage. The standard mesh reduction coefficient of molded fabric is 0.005% / kg / cm to 0.0050% / kg / cm
Between.

In other words, the reduction in eye resistance means that, while holding the two end edges of one piece of forming cloth and applying a tensile force to the forming cloth, the central part is narrowed even if the forming cloth is slightly expanded or contracted. I say the phenomenon. Then, the measured "reduction factor" is an arbitrary number and relates to the applied tensile force as a percentage of the total width along with the observed width change.

Such a high modulus of elasticity and a low coefficient of reduction in eye resistance reflect optimal mechanical stability.

In order to examine the effect on the mechanical stability of the weft, the plain weave / plain weave forming cloth used a warp with a rectangular cross section of 0.11 to 0.19 mm, the yarn passed 25 / cm through the top of the forming cloth, and Three pieces using a warp yarn having a rectangular cross section of 0.19 to 0.38 mm were woven. Three kinds of lower layer wefts having the same mesh number were woven, and the completed sample was heat-set under the same conditions. The following table shows the elastic modulus and the reduction factor of the three types of specimens. The data for specimens E1 and E2 show that nylon has an unfavorable effect on the modulus of elasticity and the coefficient of reduction of the formed fabric.

This behavior of nylon can be partially overcome by using high heatset tensile forces to force the nylon to a high level of permanent crimp, as shown in Example E3. Note that tensile strength can be improved using heatset tensile forces, but the reduction factor is adversely affected accordingly. Monofilaments made from blends of PET and TPU show more inherent crimp,
Improve mechanical stability. This is 75% PET / 25%
The following table shows the comparison between a molded cloth specimen, which is woven and heat-set in the same manner as the specimen described above using a TPU warp, and a specimen E1 containing a warp only with PET.

PET was DuPont Merge 1934, which was post-condensed in solid form and TPU was Dexin 445D.

F. Chemical Resistance In a papermaking environment, formed fabrics can be regularly cleaned, often with harsh acidic conditions. Washing with such a strong acid adversely affects the nylon monofilaments in the forming cloth, thus impairing the life of the forming cloth and impairing the promotion of abrasion resistance due to the presence of nylon in the forming cloth. Tests were performed in which coils of nylon, PET, and various blends of PET / TPU were immersed in 30% hydrochloric acid at 25 ° C. for various times. After 17 hours, the nylon was completely dissolved, but the blend of PET and PET / TPU was found to be adversely affected after 222 hours. This means that PET / TPU
Shows that the blend is much more resistant to harsh acid wash solutions than nylon.

G. Molecular weight of PET To determine whether the molecular weight of PET used for blending has any relationship with the abrasion resistance of the monofilament, except for changing the molecular weight of PET as measured from the intrinsic viscosity (I, V), 2 under the same polyurethane concentration
A blend of different monofilaments was injected. Next, the abrasion resistance of the monofilament was measured by a sand slurry test, and the results are shown in the following table.

* This is for single use PET, not for blending.

When blended using TPU from these figures, PET
It can be seen that if the molecular weight is large, the fiber becomes slightly better in abrasion resistance than low molecular weight PET. PET for both fibers
The abrasion resistance is significantly improved as compared with the control monofilament. Thus, the molecular weight of PET is unlikely to be an important factor in determining the abrasion resistance of PET-TPU blended monofilaments.

H. Comparison between ether-based and ester-based TPU In order to clarify whether ester-based TPU is more advantageous than ether-based TPU from the viewpoint of abrasion resistance, PET of the same molecular weight with an intrinsic viscosity of 1.02 is used. Was used to inject a series of blends under the same conditions. Next, the abrasion resistance of the monofilament was measured by a sand slurry test. The results are shown in the table below.

This data is based on ester-based TPU at certain TPU concentrations.
Indicates better abrasion resistance than ether-based TPU. The ester-based TPU used is Dexin 445D and the ether-based TPU is Dexin 990A
Met. The PET was DuPont Merge 1934, which was post-condensed while remaining solid.

I. Injection of monofilament In order to produce a monofilament made of a blend of PET and polyurethane, PET and polyurethane resin beads were first dried, then mechanically kneaded and filled into an injection hopper which was sent to a uniaxial extruder.

If a stabilizer is used, a predetermined amount of the stabilizer may be conveniently added to either the master patch or the PET as a concentrate. Add with stabilizer
The amount of PET or polyurethane is taken into account when determining the amount of the composition. Melting and kneading of the resin mixture occurs while the screw carries the molten mixture at about 275 ° C. through a heated cylindrical cylinder. The injection temperature may range from 260 ° C to 285 ° C, preferably from 265 ° C to 275 ° C.

After exiting the die, the monofilament is quenched in a water bath to form solid fibers. These have different draw ratios
Stretching is performed by raising the temperature to 100 ° C. between a pair of stretching rollers so that the ratio becomes 3.0: 1 to 4.5: 1. Most preferably, the maximum stretching ratio is 6.5: 1 and stretched at a high temperature of 250 ° C.,
Relax to a maximum of about 30% while heating in the relaxation stage. Next, the finished cooled monofilament is wound on a spool.

The monofilament of the invention is manufactured according to the previous process. A typical example is as follows.

Example I Post-condensation of I1 and I2 solids, 65% by weight of pellets of DuPont PET resin Merge 1934 having an intrinsic viscosity of 1.05, and Dexin 44 having a durometer hardness of 45 according to D scale.
A mixture obtained by uniformly mixing 35% by weight of pellets of 5D thermoplastic PET resin was put into a hopper of an injection molding machine and injection was performed. The injection conditions are not considered to be limited, but are as follows.

First heater zone temperature: 260 ° C Second heater zone temperature: 265 ° C Third heater zone temperature: 265 ° C Extruder die temperature: 265 ° C The extruder die has eight 0.80mm holes. I have. The final monofilament size was 0.30 mm. The monofilament was quenched 2.0 cm below the die in water at 66 ° C. The quenched monofilament is drawn in a hot air oven at a temperature of 74 ° C at a draw ratio of 3.36,
Further, the film was stretched in a hot air oven at a temperature of 230 ° C. at a final stretching ratio of 5.0 and relaxed at 280 ° C.
The finished monofilament was scooped and tested.
In a similar second run, a similar monofilament was made with the addition of 73% PET, 26% polyurethane, and 1% stabilizer.

For comparison, PET resin was injected into a monofilament using the same injection conditions as described for the PET-polyurethane blend.

Tests were conducted on the physical properties of the three types of materials, and the results are shown below.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Dale B. Johnson Canada, K2A, 1X2, Ontario, Ottawa, Fraser Avenue 512

Claims (11)

(57) [Claims] (1) a majority of polyethylene terephthalate in a weight ratio together with a hydrolysis stabilizer in a weight ratio of 0 to 5%;
A portion of the thermoplastic polyurethane by weight is mixed, the mixture is hot melt extruded from an extruder die, the extruded monofilament is quenched, and the quenched monofilament is hot drawn in at least one stage of drawing. , Relax the drawn monofilament at high temperature,
Thereafter, the polyethylene terephthalate is woven using a melt-extruded monofilament that has been cooled and then used as one of the warp and the weft of the forming cloth, and the polyethylene terephthalate is used in an amount of 60% to 90% by weight. And an intrinsic viscosity of at least 0.5 to 1.20 when measured in a solvent consisting of a mixture of phenol and 1,1,2,2-tetrachloroethane in a weight ratio of 60:40 at a temperature of 30 degrees Celsius and at a temperature of 30 degrees Celsius. In the blended monofilament, the polyurethane used is present in an amount of less than 40% to 10% by weight and has a durometer type A hardness of 95 or less or a durometer type D hardness of 75 or less. A molded fabric for the papermaking industry, characterized in that: 2. A papermaking fabric according to claim 1, which contains about 20% to 35% by weight of polyurethane. 3. The method of claim 1 wherein said blend comprises from about 0.3% to about 5% by weight.
The molded fabric for the paper industry according to claim 1, comprising a stabilizer of (1). 4. The papermaking molded fabric of claim 1, wherein said blend does not contain a stabilizer. 5. A paper fabric according to claim 1, wherein said polyurethane is a thermoplastic polyurethane based on ethers or esters. 6. A forming woven fabric used in a paper machine, wherein the forming woven fabric comprises: (a) one of a warp yarn and a weft yarn woven in a first direction which is a flow direction of the forming woven fabric; And (b) a yarn containing monofilaments woven in a second direction which is a width direction of the forming woven fabric substantially perpendicular to the first direction, and a forming woven fabric used for a paper machine woven from: The molded fabric for the paper industry according to claim 1, characterized in that: 7. A part of the monofilament constituting the surface of the forming woven fabric on which the cellulose fiber pulp slurry is laid is polyethylene terephthalate blended with thermoplastic polyurethane, and constitutes the back surface of the forming woven fabric. The papermaking molding fabric of claim 6, wherein the majority of the monofilaments are a blend of polyethylene terephthalate plus a thermoplastic polyurethane. 8. The forming woven fabric on which the cellulose fiber pulp slurry is laid is mostly monofilaments constituting polyethylene terephthalate and partially polyethylene terephthalate blended with thermoplastic polyurethane, wherein the forming is carried out. The papermaking industry forming fabric according to claim 7, wherein a part of the monofilament constituting the back surface of the woven fabric is polyethylene terephthalate, and most of the monofilament is a blend of polyethylene terephthalate and thermoplastic polyurethane. 9. The papermaking industry forming fabric according to claim 6, wherein most of the monofilaments, which are a blend of polyethylene terephthalate and thermoplastic polyurethane, are used in the width direction of the forming woven fabric. 10. The papermaking industry forming fabric according to claim 6, wherein the monofilament of the blend is used in the width direction of the forming woven fabric. 11. A multifilament yarn comprising a plurality of melt-extruded monofilaments, wherein at least a part of the monofilaments is the melt-extruded monofilament according to claim 1.