JPH08199032A - Cleaning blade for coil application roller - Google Patents

Abstract

PURPOSE: To obtain a cleaning blade for an oil application roller, which has nonstickiness and a property of not damaging a mating material on which it slides, is excellent in sliding properties and abrasion resistance and can allow an image former to provide a good image for a long time. CONSTITUTION: A cleaning blade which comes in contact with the oil application roller of an electrophotographic device, wherein the whole cleaning blade or its area which comes into contact with the roller is made of a composition essentially consisting of an injection-moldable thermoplastic fluororesin desirably a fluororubber having a number-average molecular weight of 1×10<5> to 2.5×10<5> , more desirably, a tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer and a fluoropolymer having a molecular weight as low as 50000 or below.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning blade for an oil applying roller which contacts a fixing roller of an image forming apparatus such as an electrophotographic apparatus.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus utilizing an electrostatic process such as a copying machine or an electrostatic printer, an oil applying roller is brought into contact with a fixing roller to apply a releasing oil such as silicone oil, It prevents the toner from adhering to the fixing roller and deteriorating the image.

When the oil application roller in such an image forming apparatus comes into contact with the fixing roller, toner softened by the heat roller facing the fixing roller adheres to contaminate the transfer material such as paper or the heat roller again. So it needs to be cleaned. Therefore, the edge of the cleaning blade is brought into contact with the peripheral surface of such an oil application roller to wipe off excess releasing oil, toner and other foreign matter.

As a conventional cleaning blade for an oil application roller, one in which a part or the whole including an edge portion is formed of so-called fluororubber is known. This fluororubber contains a fluoroalkyl group in the molecular structure, and commercially available products of DuPont: Viton, Ausimont: Technoflon, Daikin Industries: Daiel, etc. are used. Is weather resistance,
It is excellent in chemical resistance, non-adhesiveness, and non-damage to the mating material in sliding contact.

[0005]

However, the above-mentioned conventional cleaning blades for oil-applying rollers are inferior in sliding characteristics and abrasion characteristics to those made of fluororesin, and the cleaning characteristics are stable over time. There is a problem not to do.

Usually, in order to stabilize the cleaning property, means for adjusting the edge pressure contact force of the cleaning blade with respect to the oil application roller is adopted. However, if the pressure contact force is increased, friction increases and edge wear becomes more severe.
Such adjustment is difficult because a low pressure contact force does not provide a sufficient wiping function.

Therefore, the object of the present invention is to solve the above-mentioned problems and to provide a cleaning blade for an oil coating roller with non-adhesiveness and non-damage to a mating material which makes sliding contact, and also has sliding characteristics and wear characteristics. What is also excellent is that it has an excellent cleaning property that can provide a good image to the image forming apparatus for a long period of time.

[0008]

In order to solve the above-mentioned problems, in the present invention, in a cleaning blade which is in contact with an oil applying roller of an electrophotographic apparatus, a portion which is in contact with the oil applying roller or the entire cleaning blade is made of fluororubber. A cleaning blade for an oil-applying roller is formed from a composition containing an injection-moldable thermoplastic fluororesin and a low molecular weight fluoropolymer having a molecular weight of 50,000 or less as essential components.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION
A polymer or copolymer of unit monomers containing one or more fluorine atoms on average, which has a glass transition point of room temperature or lower and has rubber-like elasticity at room temperature, and is particularly limited. However, a wide range can be exemplified.

Fluorine rubber is bulk-polymerized at the manufacturing stage.
Polymerization methods such as suspension polymerization, emulsion polymerization, solution polymerization, catalyst polymerization, ionizing radiation polymerization and redox polymerization may be adopted. The number average molecular weight of such fluororubber (Mn) of preferably usually 5 × 10 ⁴ or more of, and from the those of the high molecular weight to obtain good results as possible, Mn7 × 10 ⁴ or more, particularly Desirably 1 × 10 ⁵ ~
It is more preferable to use one having a density of 2.5 × 10 ⁵ .

Commercially available fluororubbers satisfying the above conditions are tetrafluoroethylene-propylene copolymers manufactured by Asahi Glass Co., Ltd .: Aflas, vinylidene fluoride-hexafluoropropylene copolymers DuPont / Showa Denko. Made: Viton, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer made by Ausimont Co .: Technoflon, fluorosilicone elastomer Dow Corning made: Silastic LS, phosphazene firestone made of fluororubber Company: PNF, a perfluoro type fluororubber manufactured by Daikin Industries, Ltd .: Daier Perflo and the like.

Examples of the injection-moldable thermoplastic fluororesin (abbreviated in parentheses) in the present invention include tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene-perpolymer. Fluoroalkyl vinyl ether copolymer (EPE), tetrafluoroethylene-
Hexafluoropropylene copolymer (FEP), tetrafluoroethylene-ethylene copolymer (ETFE), trifluorochloroethylene polymer (CTFE), trifluorochloroethylene-ethylene copolymer (ECTF)
It is preferably one or more polymers selected from the group consisting of E), polyvinyl fluoride (PVF) and polyvinylidene fluoride (PVDF).

For the above-mentioned thermoplastic fluororesin, various polymerization methods such as catalyst emulsion polymerization, suspension polymerization, catalyst solution polymerization, gas phase polymerization and ionizing radiation irradiation polymerization can be adopted in the production stage. The molecular weight (Mn) is preferably 5 × 10 ⁴ or less, and particularly preferably 5 × 10 ³ to 2 × 10 ⁴ .

As a typical example corresponding to the above conditions, P
FA manufactured by Mitsui DuPont Fluorochemicals: PFA
MP10, FEP manufactured by Mitsui DuPont Fluorochemical Co .: Teflon FEP100, ETFE manufactured by Asahi Glass Co., Ltd .: Aflon COP, CTFE manufactured by Daikin Kogyo Co., Ltd .: Neoflon CTFE, PVDF manufactured by Kureha Chemical Co., Ltd .: KF polymer, PVF. Made by DuPont: Ted
lar and the like.

The composition obtained by mixing the above-mentioned fluororubber and the thermoplastic fluororesin which can be injection-molded has properties as an elastic body, and in the present invention, a low molecular weight content is added in order to impart further excellent sliding properties. A fluoropolymer is blended.

Here, the low molecular weight fluoropolymer is a fluoroolefin polymer such as tetrafluoroethylene (TFE) or tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and a main structural unit --C _n F _2n-.
Fluoropolyether having O- (n is an integer of 1 to 4), or a polyfluoroalkyl group-containing compound (having 2 to 2 carbon atoms) having a main structural unit represented by the following chemical formula 1.
20) and having a molecular weight (Mn) of 5 × 10 ⁴ or less, but those having a molecular weight of 5 × 10 ³ or less are particularly preferable in order to impart more excellent sliding characteristics.

[0017]

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Of these, (CF ₂ CF ₂ )
A TFE low-order polymer having an average particle size of 5 μm or less represented by _n is most preferable, and commercially available products thereof include Dudax AR manufactured by DuPont and Fluon Lubricant L169 manufactured by Asahi Glass Co., Ltd.
And so on.

The above-mentioned fluoropolyether having an average molecular weight of 5 × 10 ⁴ or less and having a main structural unit of —C _n F _2n —O— (n is an integer of 1 to 4) is represented by the following chemical formula 2. Can be illustrated.

[0020]

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Such a polymer has a structural unit containing a functional group such as an isocyanate group, a hydroxyl group, a carboxyl group and an ester in order to improve the affinity (adhesion) with other compounding materials and additives. Is desirable.

Specific examples of such a fluoropolyether include those represented by the following chemical formula 3, and these may be used alone or in combination with those having no functional group.

[0023]

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Further, a fluoropolyether having a functional group containing activated hydrogen and an isocyanate compound having no polyfluoropolyether group may be used in combination,
Further, it is possible to adopt a method of using a fluoropolyether having an isocyanate group and a diamine, a triamine or a diol not containing a fluoropolyether group, or a triol, which does not contain various fluoropolyether groups. Good.

In particular, it is preferable to use a combination of fluoropolyethers in which functional groups react with each other to increase the molecular weight. Examples of such compounds include those having a unit containing an isocyanate group and a group containing a hydroxyl group. Combining with units having units is likewise preferred.

As the above-mentioned polyfluoroalkyl group-containing compound, there is, for example, a compound having a polyfluoroalkyl group represented by the following chemical formula 4 and having 2 to 20 carbon atoms.
Specific examples of the compound having a molecular weight (Mn) of 5 × 10 ⁴ or less are those represented by the following chemical formula 5 (a compound having a reactive group and a polyfluoroalkyl group, and an ethylenic group having a group that reacts with the reactive group). Polymers of a reaction product with an unsaturated compound (for example, fluoroalkyl acrylate), and a reaction product of a compound having the reactive group and the polyfluoroalkyl group and various polymers having a group that reacts with the reactive group Or a polycondensation product of the above compound).

[0027]

[Chemical 4]

[0028]

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Like the above-mentioned fluoropolyether, such a polyfluoroalkyl group-containing compound is a functional group having a high affinity for improving the affinity (adhesion) of other compounding materials and additives. For example isocyanate groups,
Hydroxyl group, mercapto group, carboxyl group, epoxy group,
A compound having a unit containing an amino group, a sulfone group or the like is preferable.

The polyfluoroalkyl group-containing compound may be used singly or in combination of two or more, and the polyfluoroalkyl group-containing compound having a reactive group having activated hydrogen and the polyfluoroalkyl group may be used. You may use together with the isocyanate compound which does not. Also,
Adopting a method such as combining a polyfluoroalkyl group-containing compound having an isocyanate group with various polyfluoroalkyl group-free diamines, triamines or various polyfluoroalkyl group-free diols, triols, etc. May be.

The combination of such functional groups is preferable also from the viewpoint of increasing the strength, and specifically, it has 2 to 20 carbon atoms.
In combination with a fluoropolymer having at least one selected from a hydroxyl group, a mercapto group, a carboxyl group and an amino group, or having a polyfluoroalkyl group having 2 to 20 carbon atoms. Then
In addition, a combination of a fluoropolymer having a unit containing an isocyanate group and a fluoropolymer having a unit having a polyfluoroalkyl group having 2 to 20 carbon atoms and further having a reactive group having activated hydrogen is used. Can be mentioned.

Particularly, when a fluoroolefin polymer or fluoropolyether is used among the above-mentioned low molecular weight fluoropolymers, excellent results are obtained in terms of lubricity, and particularly a tetrafluoroethylene polymer having an average particle size of 5 μm or less is obtained. Has been found to give the most desirable results.

In the present invention, the compounding ratio of the fluororubber, the injection-moldable thermoplastic fluororesin and the low molecular weight fluoropolymer is from 50:50 in terms of the weight ratio of the fluororubber and the injection-moldable thermoplastic fluororesin. The range of 97: 3 is preferable. This is because when the blending weight ratio of the thermoplastic fluororesin exceeds 3/100, the desired composition does not have sufficient elastic properties, and when it is less than 3/100, sufficient abrasion resistance cannot be obtained.

Further, the low molecular weight fluoropolymer 5 to 5 parts by weight based on 100 parts by weight of the fluororubber and the thermoplastic fluororesin in total.
50 parts by weight is preferred. This is because if the compounding ratio of the low molecular weight fluoropolymer is less than 5 parts by weight, sufficient sliding properties cannot be obtained, and if it exceeds 50 parts by weight, the rubber-like elastic properties are impaired.

Incidentally, various additives may be blended in addition to the above components within a range not impairing the object of the present invention. For example, as a vulcanizing agent for fluororubber, isocyanate, organic peroxide, etc., antioxidant or acid acceptor such as sodium stearate, magnesium oxide, calcium hydroxide, antistatic agent such as carbon, white carbon (silica), It goes without saying that a filler such as alumina, a metal oxide, a colorant, a flame retardant, etc. may be added for convenience.

The method of mixing the above various raw materials is not particularly limited, and is a method that is generally widely used, for example, an elastomer as a main raw material, other raw materials, individually or sequentially or simultaneously with a roll mixer or the like. It may be mixed with a mixer. At this time, it is desirable to provide a temperature controller to prevent heat generation due to friction. Further, when using a roll mixer, it is more preferable to tighten the roll interval to about 3 mm or less and perform thin threading for finishing mixing.

The cleaning blade for an oil coating roller of the present invention does not require any specially limited means in its molding step, and primary vulcanization (5 to 20 minutes at 140 to 170 ° C., Pressurized 5-15
kgf / cm ² ) and then secondary vulcanization (230-280 ° C.)
For 10 to 20 hours without applying pressure).

In this case, when the secondary vulcanization is carried out at a temperature of 230 ° C. or lower, the compression set characteristic of the composition is inferior and "edge" is generated at the edge portion which is the blade edge of the blade. Also, 2
When the secondary vulcanization is carried out at a temperature of 80 ° C. or higher, the low molecular weight fluorine-containing polymer begins to decompose slightly and mechanical strength is deteriorated, which is not preferable.

Usually, the sheet material may be molded under such conditions and then cut into a desired blade shape. Further, a composite material integrally formed with a metal such as phosphor bronze, stainless steel, or steel material as the material of the cleaning blade when the primary vulcanization may be cut into a blade shape. Further, one side part of the blade including an edge part to be the cutting edge of the blade may be molded with the composition containing the above-mentioned essential components, and the other side part of the blade may be composite-molded with synthetic rubber.

Examples of the synthetic rubber include nitrile rubber, chloroprene rubber, butadiene rubber, urethane rubber, styrene rubber, butyl rubber, acrylic rubber, silicone rubber, ethylene rubber, fluorinated rubber, and other vulcanized rubber, or urethane, polyester, polyamide, and chlorinated rubber. Examples thereof include thermoplastic elastomers such as vinyl, polybutadiene and soft nylon, and liquid elastomers such as liquid urethane and liquid butadiene.

The cleaning blade according to the present invention forms a recording pattern on a medium such as a photoconductor by an electric signal applied from the outside, and the electric quantity pattern formed on the medium becomes a visible pattern. Of course, the present invention can be applied to printers that employ various conversion methods. The printing method of such a printer includes an electrophotographic method, an inkjet method, a thermal method, an optical printer method, an electronic recording method, and the like. The types of electrophotography described above include the Carlson method, light / charge injection method, optical polarization method, photovoltaic method, charge transfer method, electrolytic electrophotography method, electrostatic latent image photography method, photoelectrophoresis method, thermostat method. The plastic method can be mentioned. Further, examples of the optical printer include a laser printer, an LED (light emitting diode) printer, a liquid crystal shutter printer, and a CRT printer. Also,
As the electronic recording method, an electrostatic recording method, an electrification recording method,
Electrolytic recording method, discharge recording method, direct method,
Indirect methods are also included.

Among these image forming methods, the cleaning blade of the present invention can be applied to the wet method of applying oils. As a specific apparatus in which the wet image formation is adopted, a toner image transfer type electrostatic copying machine (PPC), a laser beam printer (LBP), a liquid crystal shutter (LCD) printer, a facsimile printer, etc. Examples thereof include a light emitting diode (LED) and a printer (CRT) using a silver halide photography method. That is, the wet image forming method to which the cleaning blade according to the present invention can be applied is a concept that generally refers to the wet system adopted in the image forming apparatus.

[0043]

EXAMPLES The raw materials used in Examples and Comparative Examples are summarized below. The mixing ratio of each component is% by weight, but the raw materials shown in (1) to (7) are shown in parts by weight based on 100 total weight of the raw materials shown in (8) to (20).

(1) Fluorine rubber [AFLAS] Asahi Glass / Nippon Synthetic Rubber Co., Ltd .: AFLAS (2) Fluorine rubber [Technoflon] Ausimont: Technoflon FOR5351 (3) Fluorine rubber [Viton] DuPont: Viton B50 (4) Fluorine rubber [elastomer] Dow Corning Co., Ltd .: Silastic LS (5) Fluorine rubber [elastomer] Daikin Industries Co., Ltd .: Daier Perflo GA50 (6) Tetrafluoroethylene-ethylene copolymer [E
TFE] Asahi Glass Co., Ltd .: Aflon COP (7) Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer [PFA] (Mitsui DuPont Fluorochemical Co .: PF
A-MP10) (8) Low molecular weight fluoropolymer [low molecular weight TFE] Asahi Glass Co., Ltd .: Lubricant L169 (9) Low molecular weight fluoropolymer (fluoropolyether) [Low molecular weight FEP] Japan Enimont Corporation: Fon Bling Z-DOLL (10) High molecular weight PTFE (Mitsui-DuPont Fluorochemical Co., Ltd .: Teflon 7J) (11) Silicone resin (Toray Silicone Co., Ltd .: trefil) (12) Carbon (van der Wirth Co., Ltd .: MT carbon) (13) Sodium stearate (general industrial material) (14) Organic peroxide (α, α'-bis (t-butylperoxy) diisopropylbenzene) (15) Polyfunctional monomer [TAIC] (triallyl isocyanurate) ) (16) Magnesium oxide [MgO] (general reagent) (17) Calcium hydroxide [C (OH) _2] (General reagent) (18) white carbon [silica] Fuji Silysia Chemical Co., Ltd. SYLYSIA 320 (19) vulcanizing agent (Showa Denko-DuPont Co., Ltd. Curative # 20) (20) a vulcanizing agent ( Showa Denko / Dupont: Curative # 30).

[Examples 1 to 10 and Comparative Examples 1 to 7] Raw materials (1) to (5) were wound around a roll mixer adjusted to a roll interval of 5 to 10 mm, and the other raw materials were mixed in the proportions shown in Table 1. And kneaded. After that, roll interval is 1m
It was adjusted to m and masticated about 10 times. For the purpose of preventing frictional heat at this time, cooling water was constantly passed through the roll to keep the roll temperature at 60 ° C or lower. Next, cooling water was stopped, steam was passed through the rolls to adjust the rubber temperature to 70 ° C. or higher and 90 ° C. or lower, and then the roll interval was returned to about 5 to 10 mm, and raw materials (6) to (11)
Was added little by little and kneaded at the compounding ratio shown in Table 1. Then, the roll interval was again narrowed to 1 mm and mastication was performed about 10 times.

A sheet having a length of 400, a width of 300, and a thickness of 1 mm made of the compound obtained in the above steps was subjected to primary vulcanization (170 ° C., 10 minutes, press pressure 7 kgf / cm ² ) and then secondary vulcanization (230 C., 16 hours, free heating). As described above, the friction and wear characteristics, the non-adhesiveness, the elastic body characteristics, and the actual cleaning property of each test piece after the vulcanization were determined. Each test method is as follows.

(A) Friction and abrasion test: The obtained sheet was punched into an annular shape having an inner diameter of 17 mm, an outer diameter of 21 mm and a thickness of 1 mm, and this was used as an aluminum jig having an inner diameter of 17, outer diameter of 21 and a thickness of 10 mm. The ring-shaped friction and wear test pieces were adhered to each other. When measuring the friction coefficient, use a thrust type friction tester as the mating material with a silicone rubber of hardness 30,
Sliding speed of 1m under the condition that silicone oil is applied
/ Min, the friction coefficient at a surface pressure of 3 kgf / cm ² was measured.
The one with a little large variation over time is indicated by a triangle, and the one with a large variation over time is indicated by a cross.
It was shown to.

Further, the wear coefficient is such that the sliding speed is 30 m / min,
Under exactly the same conditions as the friction coefficient except that the surface pressure was 1 kgf / cm ² , the wear coefficient after 50 hours (× 10 ^-10 cm ³ / k
gf · m) was examined. The results are shown in Table 3.

(B) Non-adhesiveness evaluation test: The contact angle of each test piece with water was measured with a goniometer contact angle measuring instrument,
The larger the contact angle, the better the non-stickiness was judged, and the results are shown in Table 4.

(C) Elastic body property evaluation test: Based on JIS-K6301 for the obtained sheet-shaped test piece, general properties of the elastic body include tensile breaking strength, tensile breaking elongation and hardness (JIS-A). ) Was examined and the results are also shown in Table 4.

(D) Actual machine cleaning test: The obtained sheet was cut into 220 × 8 × 1 (mm) strips,
A 10 × 220 × 0.5 (mm) phosphor bronze plate material was bonded to obtain a test blade. 20 mm diameter with this test blade and surface made of silicone rubber (30 degree product)
The roller is heated up to 120 ° C by the axial heating method, the pressing force is 500 gf, the roller rotation speed is 100 rpm, and the silicone oil and the toner are periodically supplied under the condition of 50.
I drove for hours. Then, the scraping condition of the oil and the toner after 50 hours was evaluated in three grades of good (◯ mark), slightly bad (Δ mark) and poor (x mark), and the results are also shown in Table 4.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

[Table 3]

[0055]

[Table 4]

As is clear from the results of Tables 3 and 4, in Comparative Examples 1 to 7, the friction coefficient was large from the beginning of the test, and particularly in Comparative Examples 4 and 6, the coefficient of friction exceeded 0.5 from the beginning. It was These sliding states were unsatisfactory because the stick-slip was continuous rather than slipping and the friction amplitude was large.

On the other hand, in each of Examples 1 to 10, the change over time in the friction coefficient over 15 hours was stable at a low value of 0.14 to 0.19, and the wear coefficient was also a measure of wear resistance. It was 20 or less, which was good. Further, since Examples 1 to 10 have elastic body characteristics, they do not damage the oil application roller that makes sliding contact, and it is clear from the results of the actual machine cleaning test that they have excellent cleaning properties.

[0058]

As described above, according to the present invention, the portion of the cleaning blade that comes into contact with the oil application roller or the entire cleaning blade is made of fluororubber, a thermoplastic fluororesin such as PFA that can be injection-molded, and a molecular weight of 50.
Since it was formed from a composition containing a low molecular weight fluorine-containing polymer of 000 or less as an essential component, it has excellent non-adhesiveness, non-damage to the mating material in sliding contact, and excellent sliding and wear characteristics. Therefore, there is an advantage that the image forming apparatus has an excellent cleaning property capable of providing a good image for a long period of time.

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Claims (6)

[Claims] 1. A cleaning blade in contact with an oil application roller of an electrophotographic apparatus, wherein a portion in contact with the oil application roller or the entire cleaning blade contains fluororubber, an injection moldable thermoplastic fluororesin and a low molecular weight of 50,000 or less. A cleaning blade for an oil application roller, which is formed from a composition containing a fluoropolymer as an essential component. 2. The number average molecular weight of the fluororubber is 1 × 1.
The cleaning blade for an oil application roller according to claim 1, having a size of 0 ^{5 to} 2.5 × 10 ⁵ . 3. The injection-moldable thermoplastic fluororesin is tetrafluoroethylene-perfluoroalkylvinylether copolymer, tetrafluoroethylene-hexafluoropropylene-perfluoroalkylvinylether copolymer, tetrafluoroethylene-hexafluoro. Propylene copolymer, tetrafluoroethylene-ethylene copolymer, trifluorochloroethylene polymer,
The cleaning blade for an oil coating roller according to claim 1, which is one or more polymers selected from the group consisting of trifluorochloroethylene-ethylene copolymer, polyvinyl fluoride and polyvinylidene fluoride. 4. The oil coating according to claim 1, wherein the low molecular weight fluoropolymer is one or more polymers selected from the group consisting of fluoroolefin polymers, fluoropolyethers and polyfluoroalkyl group-containing compounds. Cleaning blade for rollers. 5. The cleaning blade for an oil coating roller according to claim 1, wherein the low molecular weight fluoropolymer is a tetrafluoroethylene low order polymer. 6. The weight ratio of the fluororubber to the injection-moldable thermoplastic fluororesin is in the range of 50:50 to 97: 3, and the total amount of the low molecular weight fluoropolymer is 5 to 50 per 100 parts by weight. The cleaning blade for an oil applying roller according to claim 1, which is part by weight.