JP2935939B2 - Polyester fabric for air bags - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyester fabric for an air bag. More specifically, the present invention relates to a polyester fabric for an air bag, in which the vehicle interior pollution due to fine particles generated during inflation is extremely small and a sufficient bag internal pressure is generated.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 64-70247 discloses a technique in which a woven fabric which is not coated or impregnated with a resin (hereinafter referred to as "non-coated woven fabric") is calendered to obtain the same properties as a coated fabric for an air bag. It is disclosed in the official gazette. However, the air permeability of the fabric described in this publication is as large as 0.5 cc/cm ² /sec/0.5 inchAq even in the fabric having a double-sided smooth structure by the double-sided calender in the examples, and the effect of preventing vehicle interior pollution is unsatisfactory. Is enough. Further, in this publication, it is not suggested at all that an air bag capable of preventing vehicle contamination and obtaining bag internal pressure similar to a coated fabric can be obtained by using a fabric having a non-smooth surface.

Further, in US Pat. No. 4,977,016 (Japanese Patent Laid-Open No. 4-2835), calendering is performed using a polyester having an air permeability of 0.5 cc/cm ² /sec/0.5 inchAq or less. An uncoated fabric for an air bag is disclosed. Also, in US Pat. No. 5,010,663 (Japanese Patent Laid-Open No. 4-2835), 1.5 cc/c
A similar fabric for an air bag of m ² /sec/0.5 inch Aq or less is disclosed.

The polyester fabrics disclosed in these documents are both double-sided smooth fabrics obtained by double-sided calendering. And, as for the woven fabric with the double-sided smooth structure obtained by the double-sided calendaring, its air permeability is large, and even in the description of the example, it exceeds 0.1 cc/cm ² /sec/0.5inchAq, and the inside of the vehicle is completely polluted. Cannot be prevented.

Further, US Pat. No. 4,921,735 (JP-A-1-122752) also discloses a calendered fabric for an air bag, the air permeability of which is 0 to 0.53 cc/cm. ^{A 2/} sec/0.5 inch Aq fabric is disclosed. However, no specific numerical value is described in the examples, and when the air permeability is 0, it is not suitable for an air bag. In addition, the details of calendar processing are not specified, and the problem of vehicle interior pollution is not recognized at all.

However, when these fabrics are actually applied to an air bag, a large amount of fine particles contained in the inflation gas is generated and the interior of the vehicle is considerably polluted, and the inflation inner pressure is low, which is not suitable for practical use. This is because with a double-sided smooth structure using a double-sided calender, the surface of the fabric is smooth and the bulkiness is poor, so it is not possible to filter fine particles on the fabric surface inside the bag. Due to the large size, fine particles pass out of the bag through the space between the fabrics, and similarly, since the air permeability is large, a large amount of gas passes through the fabric during inflation, and as a result, the internal pressure of the bag cannot reach the required internal pressure.

On the other hand, in a woven fabric having a one-sided non-smooth structure by a one-sided calender, although it has surface filtration performance, since the air permeability is still large, fine particles pass through the gaps between the fabrics, and the air permeability is large, so that the bag is blown during inflation. The internal pressure does not rise to the required internal pressure. When the inflation pressure is low, it is dangerous because the cushion effect cannot be sufficiently exerted when the occupant collides with the bag.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a non-coated fabric for an air bag, which is less likely to be contaminated in the vehicle by fine particles in inflation and easily reaches a necessary bag inner pressure.

[0009]

[Where a is the longest straight line perpendicular to the long axis connecting each point on the long axis of the flat cross section of the warp or weft on the non-smooth side to the point on the outer surface of the fabric in the cross section of the woven fabric. Of the longest straight line b'which is perpendicular to the long axis connecting the points on the long axis and the points on the inner surface of the fabric of the yarn. ), A is the longest of the straight lines perpendicular to the long axis connecting the points on the long axis of the flat cross section of the warp or weft on the smooth surface side with the points on the outer surface of the woven fabric in the shape of the cross section of the woven fabric. Is the length (μm) of the longest straight line B′ that is perpendicular to the long axis connecting the points on the long axis and the points on the inner surface of the fabric of the yarn. ) Is shown. ]

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 shows a cross-sectional structure of the polyester fabric for an air bag of the present invention. As shown in FIG. 1, the polyester fabric for an air bag of the present invention has one surface M having a smooth structure and the other surface N having a non-smooth structure. As described above, the double-sided smooth woven fabric is poor in bulkiness, so that the surface filtration performance of fine particles is small and the internal pressure of the bag is insufficient.
Since the surface M is smooth, low air permeability is obtained, and the non-smooth surface N has bulkiness and contributes to the surface filtration function.

However, with only the low air permeability of the surface M,
Since it is difficult to bring the internal pressure of the airbag to the required internal pressure at the time of collision with the occupant, the surfaces M and N have the structures represented by the formulas (1) to (3) in the uncoated state. First, it is necessary that a≧A. Here, a is as shown in FIG.
The length (μm) of the longest straight line a′ of the straight lines perpendicular to the long axis connecting each point on the long axis of the flat cross section of the warp or weft on the non-smooth side and the point on the outer surface of the fabric Show. On the other hand, A is
The length (μm) of the longest straight line A′ among the straight lines perpendicular to the long axis connecting each point on the long axis of the flat cross section of the warp or weft on the smooth surface side and the point on the outer surface of the woven fabric .. The major axes of both flat cross sections are substantially parallel to each other.

The fabric of the present invention is used in an air bag,
The non-smooth surface N is used inside the bag, and the smooth surface M is used outside the bag. In the above equation, when a is smaller than A, the bulkiness of the yarn facing the inside of the bag is small, and the surface filtration performance of fine particles is lowered during inflation, resulting in increased vehicle interior pollution. The surface filtration performance refers to a function of capturing fine particles between the single fibers on the surface of the woven fabric when the inflation gas collides with the inner surface of the bag and thereafter the gas passes along the inner surface. If the surface filtration performance is low, most of the fine particles in the inflation gas are not trapped between the single fibers on the inner surface of the bag but are discharged from the vent hole to the outside of the bag, which pollutes the inside of the vehicle.

Here, a is preferably in the range of 20 μm to 100 μm. When a is less than 20 μm, the bulkiness of the non-smooth surface N decreases, and the surface filtration performance of fine particles decreases during inflation, resulting in increased vehicle interior pollution. On the other hand, when it exceeds 100 μm, the bulkiness becomes too large,
The fine particles pass through the bulk of the single fiber, which also increases the pollution in the vehicle. More preferably, a is in the range of 30 to 80 μm.

Further, A is preferably in the range of 1 to 30 μm. When A is less than 1 μm, the bulkiness of the yarn forming the outside of the bag is so small that the tear strength of the woven fabric is lowered and the fabric is easily damaged by inflation. Meanwhile, 30
When the thickness exceeds μm, the air permeability increases, so that the amount of inflation gas passing vertically through the fabric increases, and the pollution in the vehicle also increases. Moreover, the internal pressure of inflation does not rise, which causes a safety problem. Also, facial abrasion is likely to occur. More preferably, A is in the range of 2 to 25 μm.

Next, it is necessary to satisfy the formula. (A+b)≧(A+B) In the formula, b is the longest straight line that is perpendicular to the long axis connecting each point on the long axis of the flat cross section on the non-smooth surface side and the point on the inner surface of the fabric of the yarn. The length (μm) of b′, B is the length of the longest straight line B′ of the straight lines perpendicular to the long axis connecting the points on the long axis on the smooth surface side and the points on the inner surface of the fabric of the yarn. (Μm) is shown.

When (A+B) is larger than (a+b), the air permeability of the fabric is increased, so that a large amount of inflation gas vertically passes through the fabric during inflation, resulting in increased pollution in the vehicle. Also, since the air permeability is large, the inflation internal pressure does not rise to the required internal pressure, which poses a safety problem.

Further, it is necessary to satisfy the formula. 0.10≦[a/(a+b)]≦0.50 When a/(a+b) is less than 0.10, the bulkiness of the yarn facing the inside of the bag is small, and the surface filtration performance of fine particles during inflation is insufficient. As a result, vehicle interior pollution increases. On the other hand, when it exceeds 0.50, the bulkiness of the yarn is so large that the fine particles pass through the bulk of the single fiber, and the pollution in the vehicle also increases. a/(a+b)
Is preferably in the range of 0.20 to 0.40.

Further, it is necessary to satisfy the condition of 0.01≦[A/(A+B)]≦0.30. A/(A+B) is 0.0
When it is less than 1, the yarns facing the outside of the bag have too low a bulkiness, so that the tear strength of the woven fabric is lowered and the yarn is easily damaged by inflation. On the other hand, if it exceeds 0.30, the air permeability will increase and the amount of inflation gas that passes vertically through the fabric will increase, so pollution inside the vehicle will also be significant, and the inflation pressure will not rise to the required pressure for safety. I have a problem. Further, there is a possibility that facial ablation may occur when the occupant collides. A/
(A+B) is preferably in the range of 0.02 to 0.20.

In the present invention, the values of a, b, A and B can be obtained by measuring the cross section of the constituent yarn in the cross section of the fabric photographed by an electron microscope.

Further, its air permeability is 0.1 cc/cm ² /sec/
It must be less than 0.5inchAq. When the air permeability of polyester fabric exceeds 0.1 cc/cm ² /sec/0.5inchAq, the amount of inflation gas that passes vertically through the fabric increases, which causes significant pollution of the interior of the vehicle due to fine particles that have passed through the fabric, and also inflation. The internal pressure does not rise to the required internal pressure, causing a safety problem. The preferred range of air permeability is 0.
It is less than 08cc/cm ² /sec/0.5inchAq.

The polyester fabric for an air bag of the present invention forms a non-smooth surface by imparting bulkiness due to the shrinkage of the fabric in the setting step after scouring and drying, and calendering only one surface in the subsequent calendar step. It can be obtained by forming a smooth surface.

That is, by performing roll-setting in at least two stages of low temperature and high temperature after scouring and drying, bulkiness due to uniform and good shrinkage can be imparted and a non-smooth surface can be formed. The preferable range of the set temperature is 130 to 170° C. for the low temperature roll and 160 for the high temperature roll.
~220°C. Due to the uniform shrinkage on the low temperature roll and the high shrinkage on the high temperature roll, preferable bulkiness of the non-smooth surface can be exhibited. It is difficult to obtain a uniform and high shrinkage ratio by a one-stage roll set. Further, in the case of setting with a tenter, since the flatness of the woven fabric is lost, calendar processing becomes difficult.

The polyester filament yarn capable of exhibiting preferable bulkiness has a dry heat shrinkage at 150° C. of 3 to 12% and a boiling water shrinkage of 1.5 to 6%.
Are preferred.

If the dry heat shrinkage percentage at 150° C. exceeds 12%, the shrinkage is too large in the set after scouring, so that the uniform shrinkage is hindered and the air permeability is low and a stable fabric cannot be obtained. On the other hand, if it is less than 3%, the shrinkage is too small to obtain a highly bulky fabric. A more preferable range of the dry heat shrinkage ratio at 150°C is 4 to 10%.

On the other hand, if the boiling water shrinkage exceeds 6%, the shrinkage is too large when drying or setting after scouring, and similarly, a fabric having low air permeability and stable cannot be obtained. On the other hand, if it is less than 1.5%, the shrinkage is too small to obtain a woven fabric having high bulkiness. A more preferable range of boiling water shrinkage is 2 to 5
%.

Furthermore, in the processing step, in order to obtain a non-smooth structure having good bulkiness, 1
~7%, more preferably 2-5%, 8-28 after setting
%, more preferably 10 to 23%.

Next, single-sided calendering in which a metal roll is selectively brought into contact with only one surface of the obtained processed surface having a non-smooth structure on both sides is performed. Thereby, it is possible to impart a smooth structure to the other surface while leaving the non-smooth structure on one surface of the woven fabric. Calendar processing is generally performed by a pair of upper and lower metal/elastic calendar rolls, and the surface processed by the metal roll has a smooth structure.

The preferred calendering conditions for obtaining a smooth surface which realizes the low air permeability of the present invention are that the surface temperature of the metal roll is 150 to 220° C., more preferably 160 to 2° C.
00° C., roll pressure is 500 to 900 kg/cm, more preferably 800 to 900 kg/cm, roll speed is 1
˜20 m/min, more preferably 2 to 10 m/min.

At this time, for example, a contact and/or non-contact type heater may be provided immediately before the calender to preheat the woven fabric, or if the fabric is processed at a low speed of 1 to 4 m/min, a better smooth surface can be obtained.

To make the opposite surface sufficiently non-smooth,
It is desirable that the surface temperature of the elastic roll or the metal roll on the non-smooth surface side is lower than the surface temperature of the metal roll on the smooth surface side by at least 30° C., more preferably by 40° C. or more.

The calendering is performed at least once on only one side of the fabric. However, it may be done more than once. When both sides are processed, both sides of the woven fabric become smooth, and the surface filterability on the inner surface of the air bag deteriorates.

The polyester filament yarn constituting the polyester woven fabric having the cross-sectional structure as described above, as well as the warp and weft yarns, needs to have a twist coefficient of 2,500 or less, preferably 2,100 or less. Twist factor 2.5
If it exceeds 00, the air permeability is not sufficiently lowered and the airtightness becomes poor. As a result, in-vehicle pollution occurs because the passage of fine particles during inflation cannot be suppressed. In addition, the bulkiness of the non-smooth surface is also reduced, and the surface filterability is reduced, which similarly causes a problem of vehicle interior pollution. Furthermore, the internal pressure of inflation also becomes low.

On the other hand, in the case of no twist, the surface filterability is most excellent, but the weavability is lowered, and as a result, it is difficult to obtain a high-density fabric, so that the air permeability is somewhat increased and the internal pressure of inflation is slightly lowered.

As the twisting coefficient conditions that weavability is good, air permeability is small, and surface filterability is good, the twisting coefficient of the warp is 1.
It is 300 to 2,500, and the case where the weft yarn is not twisted. The twist coefficient is represented by the product of the square root of the denier of the filament yarn and the twist number (t/m).

In the polyester woven fabric of the present invention, the filament yarn constituting the polyester woven fabric is preferably composed of 0.5 to 3.0 de single fibers. Single fiber denier is 0.
If it is less than 5 de, fluff is likely to occur, and it becomes difficult to weave a high-density fabric, and a fabric having a high air permeability is obtained, so that the vehicle interior is significantly contaminated. In addition, the inflation pressure does not rise, making it difficult to ensure safety. On the other hand, if it exceeds 3.0 de, even if it has a non-smooth structure, it becomes difficult to capture the fine particles, the surface filtration property is deteriorated, and the air permeability is increased, so that the inside of the vehicle is significantly contaminated and the inflation pressure is also increased. Not doing so reduces safety.
The more preferable range of the single fiber denier is 1.0 to 2.5 d.
It is e.

The number of filaments forming the filament yarn is preferably 140 to 840. If the number of filaments is less than 140, fine particles cannot be sufficiently captured between the single fibers, resulting in a decrease in surface filtration performance and an increase in vehicle interior pollution. If the number of filaments exceeds 840, weaving becomes difficult. The more preferable range of the number of filaments is 20
It is 0-600.

The denier of the filament yarn is 200
~600 de is preferred. 200 de filament yarn
If less than, the burst strength of the fabric is insufficient. On the other hand, when it exceeds 600 de, the crimp structure due to the shrinkage of the woven fabric in the setting step is not sufficiently developed, and the bulkiness of the non-smooth surface is lowered, so that the surface filterability is lowered and the vehicle interior pollution is increased. A more preferable range of yarn denier is 300 to 550 de.

What is not forgotten here is the cover factor of the fabric. The cover factors of the warp direction and the weft direction of the fabric are both after calendering,
It is preferably 1,050 to 1,300. In terms of fabric density, when polyester filaments having a yarn denier of 420 de are used, the warps and wefts each correspond to about 51 to 63 filaments/inch. The warp and weft densities are preferably the same.

The term "cover factor in the warp direction" as used herein means the product of the square root of de of the warp yarn and the warp density (pieces/inch). The cover factor in the weft direction means the product of the square root of the yarn denier of the weft and the weft density (pieces/inch). If the cover factor in the warp direction or the weft direction is less than 1,050, the air permeability will increase. On the other hand, if this value exceeds 1,300, the fabric becomes coarse and rigid, the texture is deteriorated, and the air permeability is not improved so much. At the same time, the bulkiness of the non-smooth surface decreases. The cover factor is more preferably 1,080 to 1,250.

In terms of fabric density, yarn denier is 420d.
When the polyester filament yarn of e is used, it is preferably about 51 to 63 yarns/inch, and 53 to 61 yarns/inch in both the history and the history.
Inches are even more preferred.

As the woven structure, 1/1 plain woven fabric and 2/2 mat woven fabric are preferable, but 2/1 or 2/
It may be a twill fabric or a ripstop fabric. However, the tissue with the lowest air permeability is plain weave.

In the present invention, examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyhexylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene-1,2-bis(phenoxy)ethane-4,4'-.
In addition to dicarboxylate, polyethylene isophthalate, polybutylene terephthalate/naphthalate,
Mention may be made of copolymerized polyesters such as polybutylene terephthalate/decane dicarboxylate. Among them, polyethylene terephthalate having a good balance of mechanical properties and fiber forming properties is particularly preferable.

[0043]

The polyester woven fabric according to the present invention has a low air permeability because one side has a smooth structure, and the other side has a non-smooth structure. Since the structure is bulky, it has an excellent surface filterability that collects fine particles in inflation gas, can prevent vehicle interior pollution, and can reach the internal pressure required during inflation, providing a sufficient cushion. It can be effective.

Further, it is a fabric having an extremely low air permeability of 0.1 cc/cm ² /sec/0.5 inchAq or less, which has been difficult to achieve by the conventional non-coated fabric, and prevents the in-vehicle pollution due to the vertical passage of the inflation fine particles through the fabric. The required inflation pressure can be achieved.

Further, by using the smooth surface on the side where the occupant comes into contact, that is, on the outside of the airbag, it is possible to prevent the occurrence of facial abrasion when the occupant is impacted, and by arranging the non-smooth surface on the inside, the fine particles are provided. Due to the surface filtration performance of the above, it is possible to effectively capture the inflation fine particles flowing along the inside of the bag and prevent the pollution in the vehicle.

The polyester fabric for an air bag of the present invention can be used for an air bag for driver seats and an air bag for passenger seats.

[0047]

EXAMPLES The present invention will be described in more detail with reference to examples. The physical properties of the fibers and the woven fabric and the evaluation of the air bag in the examples were performed according to the following methods.

Air permeability : Measured using FX3300 (manufactured by Textest, Switzerland) with a 100 cm ² orifice at a water column pressure of 0.5 inch (124 pa). a, A, b, B : The cross section of the woven fabric was photographed by an electron microscope and measured approximately.

Dry heat shrinkage : Calculated by the following formula after shrinking a polyester filament for 30 minutes at 150° C. without twisting. Dry heat shrinkage (%)=((L−L ₀ )/L)×100 (where L is the filament length before shrinking, L ₀ is the filament length after shrinking) Shrinkage of boiling water : No polyester filament It was obtained in the same manner as the calculation of the dry heat shrinkage ratio after shrinking in twisted water for 30 minutes as twisted.

Inflation internal pressure and surface filterability : A module containing a 60-liter air bag for driver's seat was equipped with a type 4 type inflator manufactured by Morton International, which was heated at 95° C. for 6 hours or more and immediately subjected to inflation. Was carried out. The internal pressure of the bag at this time was measured with a strain gauge (manufactured by Kyowa Denki Co., Ltd.), and the surface filterability of the non-smooth surface was determined from the degree of contamination inside the bag. Comprehensive evaluation : Determined by comprehensively judging the results of the inflation inner pressure value of the air bag and the surface filterability inside the bag.

Examples 1 to 7 and Comparative Examples 1 to 7 Polyester filament yarns shown in Tables 1 and 2 were used as warp yarns and weft yarns, a high density plain woven fabric was woven by a rapier loom, and then scouring and heat setting under various conditions. Then, single-sided calendaring was performed to prepare polyester woven fabrics shown in Tables 1 and 2. Next, using this woven fabric, a 60-liter airbag for a driver's seat was formed. At that time, inflation was carried out by arranging the smooth surface so as to be outside the bag. The obtained woven fabric properties and air bag performance are shown in Tables 1 and 2.

[0052]

[Table 1]

[0053]

[Table 2]

Comparative Examples 8 to 9 According to the comparative example described in Example 1 of US Pat. No. 4,977,016, only one side was calendered to obtain a fabric for an air bag. That is, 4 as warp
40 de/100 fil (twist number: 3.25 t/inch=
130t/m), weft 440de/100fil
2 using polyester filament yarn of (twist number: 0)
A x2 grid fabric was obtained and this fabric was 70 psi, 360°
Calendering on one side under the condition of F, 1.82C
FM air permeability (calendaring once), and 1.42C
A fabric for an air bag having an air permeability of FM (calendering twice) was obtained. When the characteristics of the obtained air bag fabric and air bag were evaluated, the results shown in Table 3 were obtained.

[0055]

[Table 3]

As shown in Table 3, the number of twists of the warp is large, and the calender condition is 70 psi (corresponding to 65-80 tons/70 inch width in the description, and linear pressure of 365-450 kg/cm). Therefore, even if calendering is performed twice on one surface, a sufficient one-sided smooth structure cannot be obtained. For this reason, the internal pressure of inflation was insufficient, and the generation of fine particles passing through the woven fabric was large.

[0057]

According to the present invention, it is possible to provide a polyester woven fabric for an air bag capable of sufficiently preventing the vehicle interior contamination due to the fine particles in the inflation gas and achieving the required inflation inner pressure even in the non-coated state. You can

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a polyester fabric for an air bag having one surface of the present invention having a non-smooth structure.

[Explanation of symbols]

M smooth surface of the fabric N non-smooth surface of the fabric a'a straight line perpendicular to the long axis connecting each point on the major axis of the flat cross section of the warp or weft on the non-smooth surface side and the point on the outer surface of the fabric of the thread The longest straight line b'The longest straight line A'which is perpendicular to the long axis connecting each point on the long axis and the point on the inner surface of the fabric of the yarn A'The length of the flat cross section of the warp or weft on the smooth surface side The longest straight line that is perpendicular to the long axis connecting each point on the axis to the point on the outer surface of the fabric of the yarn B', and the long axis connecting each point on the long axis to the point on the inner surface of the fabric of the yarn Longest straight line among vertical straight lines f Single fiber

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) D03D 1/02

Claims (4)

(57) [Claims] 1. A woven fabric comprising flat polyester filament yarn twisted with a twisting coefficient of 2,500 or less,
One surface thereof has a smooth structure and the other surface has a non-smooth structure, and in the non-coated state, the smooth or non-smooth structure is represented by the following formulas and the air permeability thereof is 0.1 cc/c.
A polyester woven fabric for an air bag, which has a m ² /sec/0.5 inch Aq or less. a≧A (a+b)≧(A+B) 0.10≦[a/(a+b)]≦0.50 0.01≦[A/(A+B)]≦0.30 [where a is a cross section of the woven fabric] , The length (μm) of the longest straight line a'of the straight lines perpendicular to the long axis connecting the points on the long axis of the flat cross section of the warp or weft on the non-smooth side and the points on the outer surface of the fabric B is the length (μm) of the longest straight line b′ of the straight lines perpendicular to the long axis connecting each point on the long axis and the point on the inner surface of the fabric of the yarn, and A is the warp on the smooth surface side. Or the length (μm) of the longest straight line A'of the straight lines perpendicular to the long axis connecting each point on the long axis of the flat cross section of the weft and the point on the outer surface of the fabric
B is the length (μm) of the longest straight line B′ of the straight lines perpendicular to the long axis connecting the points on the long axis and the points on the inner surface of the fabric of the yarn.
Indicates. ] 2. The polyester woven fabric for an air bag according to claim 1, wherein a is in the range of 20 to 100 μm. 3. A is in the range of 1 to 30 μm.
Or the polyester fabric for an air bag according to 2. 4. The filament denier of the filament yarn is 0.
5 to 3.0 denier and 14 filaments
The polyester fabric for an air bag according to any one of claims 1 to 3, wherein the polyester fabric is 0 to 840.