JPH01238671A - Toner for developing electrostatic image - Google Patents

Abstract

PURPOSE:To obtain a toner for developing electrostatic image having improved stability of durability, fixing effect, and offset resistance, reduced scattering tendency of the toner at high temp. and in high humidity, and to obtain a distinct image contg. no unevenness of black color in a solid part, by incorporating a specified nonlinear polyester into a binder. CONSTITUTION:A nonlinear polyester obtd. by a condensation reaction of a polymer component contg. a >=3 valent monomer as a component for the reaction, wherein a peroxide value of the polyester is <=10, is incorporated into a binder. Further, a parting agent having <=5 peroxide value is also incorporated. Suitable >= tervalent monomer is, for example, sorbitol, 1,4-sorbitan, 1,2,4-benzene tricarboxylic acid, etc. The >= tervalent monomer component is preferred to be contained by 0.1-80, more pref. 5-50mol.% basing on an alcohol component or acid component as a structural unit of a polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a toner for developing electrostatic images formed in electrophotography, electrostatic recording, electrostatic printing, or the like.

[Background of the invention]

As a conventional electrophotographic method, U.S. Patent No. 2,297,691
No. 2.357.809, etc.
An electrostatic charge image is formed on the surface of the photoreceptor, and the electrostatic charge image is made into a toner image using a dry developer made of colored fine powder.
After the toner image is transferred to a transfer sheet such as paper, it is permanently fixed by heating, pressure, etc. to form a copy image.

Recently, copying machines have been trending toward faster speeds and smaller sizes, and as a fixing process to meet these demands, a heated roller fixing system that has good thermal efficiency, a compact mechanism, and is capable of increasing speed has been preferably used.

However, in the heating roller fixing method, because the heating roller surface and the toner image surface come into contact, the so-called "offset phenomenon" occurs in which the toner is transferred to the heating roller surface and then transferred to the paper that is fed next, staining the image. Occur.

In order to prevent such offset phenomenon, especially hot offset, Japanese Patent Publication No. 51-23354 proposes to use a styrene-based cross-linked resin as a toner binder. The temperature rises, and under normal fixing conditions, the image becomes unfixed, causing stains due to low-temperature offset in the unfixed area.

In order to deal with the above hot offset and low temperature offset (poor fixing properties), Japanese Patent Publication No. 11902/1983 proposes the use of a polyester resin having a three-dimensional network structure as a toner binder.

In addition, as an attempt to use the above-mentioned non-linear polyester as a binder in combination with a mold release agent, an offset prevention agent (Japanese Patent Laid-Open Publication No. 1986-1992-1) was added to polyester containing 5% or more of chloroform-insoluble matter.
No. 11953), non-linear polyester with melt viscosity of 100
cp or less (Japanese Patent Application Laid-open No. 61-62052), non-linear polyester penetration rate of 4 or less (Japanese Patent Application Laid-Open No. 61-62)
There is a disclosure of a technique that applies a combination such as No. 2055).

However, the present inventors conducted a detailed study and discovered that there is a difference between production lots of such polyester resin.
The degree of oxidation causes large flaking, and although toners using these toners are somewhat satisfactory in terms of preventing the offset phenomenon and improving fixing properties, the image characteristics under high temperature and high humidity and It has been found that this often affects the durability of the roller fixing device.

Furthermore, it has been found that the above-mentioned tendency is more pronounced when the wax contains a considerable amount of free alcohol, fatty acids, or peroxides.

That is, since the esterification reaction of the non-linear polyester is carried out at a considerably high temperature, if a small amount of oxygen is mixed into the reaction system, oxidation proceeds and peroxides and other decomposition products are produced. On the other hand, in non-linear polyester, if a large amount of residual C0OH or OH groups or a large amount of peroxide is present, oxidation progresses during the toner kneading process, or decomposition due to ozone generated by corona discharge in the copying machine. The concentration of these functional groups increases further. Furthermore, when a mold release agent such as wax is contained in addition to the Hinta resin, if the mold release agent contains peroxide, the above-mentioned tendency will be aggravated, and the amount of moisture absorbed by the toner will increase.
This results in a decrease in the charge amount (Q/M) and softening point (Tsp) per toner.

Therefore, when copying is performed many times in an environment of high temperature and high humidity, the constancy of the image is lost, such as increased fogging, toner scattering, and occurrence of solid black problems where white background areas intersect with solid black images. Further, toner gradually adheres and accumulates on the surface of the heating roller of the heating roller fixing device, shortening the life of the fixing roller, and the toner accumulated on the heating roller transfers to the back side of the transfer paper, causing backside stains.

[Purpose of the invention]

The present invention addresses the above-mentioned problems, and an object of the present invention is to improve physical properties (Q/M) without inconveniences during toner formulation.
, Tsp, etc.) and provides a stable and highly durable toner.

Another object of the present invention is to provide an electrostatic image developing toner which has good fixing properties and anti-offset properties and is suitable for heating roller fixing.

Another object of the present invention is to provide static charge that does not cause fogging, toner scattering, or uneven solid black even after repeated use in high temperature and high humidity environments, has excellent durability, and provides clear image characteristics. An object of the present invention is to provide an image developing toner.

Another object of the present invention is to provide an electrostatic image developing toner which can significantly extend the life of the heating roller without causing heating roller stains or backside stains.

[Structure of the invention]

The object of the present invention is to provide a nonlinear polyester having a peroxide value of 10 or less, which is obtained by a condensation reaction of a monomer component containing a trivalent or higher polyvalent monomer as a reaction system component. This is achieved with an electrostatic image developing toner containing a non-linear polyester as a binder.

In addition, when a mold release agent is contained in the embodiment of the present invention, it is preferable that the peroxide value of the mold release agent is 5 or less.

The above-mentioned condensation reaction is a so-called esterification reaction, and the esterification reaction mainly involves condensation, but generally involves polymerization and addition reactions.

In addition, the peroxide value
POv (hereinafter referred to as POv) is a value that indicates the content of peroxide, which is unstable in the autoxidation of oils and fats, and the potassium iodide method is most commonly used. .

That is, it is based on a reaction in which iodine is liberated from potassium iodide in peroxide or glacial acetic acid, and the iodine content is quantified with sodium thiosulfate. For more details, please refer to the general analysis document.

In the present invention, it was measured by the following method.

A solution containing 0.1 to 0.159 of the sample is weighed and dissolved in benzene or chloroform 2 to 5 mρ. Add 1 m of saturated potassium iodide aqueous solution (1, 30 mQ of glacial acetic acid, replace with carbon dioxide, and leave in a dark place at room temperature for 10 to 15 minutes. Dilute with 30 to 50 mff of water from which dissolved oxygen has been removed through carbon dioxide. , free iodine is titrated with O, IN aqueous sodium thiosulfate using a starch indicator.

[Actions and effects of the present invention]

The polyester resin used in the binder of the toner of the present invention contains a trivalent or higher valent monomer, thereby giving the polyester resin a three-dimensional structure, improving the release agent during melting, and improving anti-offset properties. In addition, polyester resin easily melts even at low temperatures and has good melt penetration into paper at low temperatures, making it possible to prevent low-temperature offset.

However, in polyester resins that are given a three-dimensional structure by using the above-mentioned monomers with a valence of 3 or more, there is no opportunity for reaction due to steric hindrance, and unreacted -Coo)I from the monomers with a valence of 3 or more is not available. A large amount of groups or -OH groups remain.

If a considerable amount of peroxide is present in such a polyester resin, it may cause problems during toner manufacturing processes such as heating melting and kneading.
Alternatively, the concentration of terminal groups such as -COOH groups or -OH groups in the toner or on the toner surface further increases and progresses due to progress of oxidation due to ozone generated from the charger and transfer device in the copying machine. Therefore, when copying is performed many times using such a toner, the adsorption of moisture in the air to the toner surface gradually increases. When moisture adsorption becomes excessive, especially under high temperature and high humidity conditions, the charge on the toner surface tends to leak, reducing the amount of charge on the toner, resulting in increased fogging and static electricity between toner particles and carrier particles. Developability deteriorates due to toner scattering due to decreased adhesion, expansion of charge distribution (increase in low-charge toner particles), and decreased fluidity of toner particles due to moisture adsorption, resulting in solid black images and undeveloped white backgrounds. Areas appear and the uniformity of solid black is impaired.

Due to these factors, the durability of the developer is eventually lost.

Furthermore, in the heating roller fixing process, a portion of the toner tends to adhere to and accumulate on the heating roller surface due to a decrease in the softening point of the toner as oxidation progresses on the toner surface. When this phenomenon becomes excessive as the number of copies increases, toner accumulated on the upper roller of the heating roller transfers to the lower roller, contaminates the lower roller, and accumulates on the lower roller during fixing. The toner transfers to the surface of the transfer paper, causing stains on the back surface.

Therefore, the toner of the present invention was studied with a focus on preventing the progress of oxidation, which is considered to be the main cause of the above-mentioned problems.As a result, the POV of the polyester resin according to the present invention was
It has been discovered that the problem can be solved by selecting a POV of 10 or less and a POV of a mold release agent used in combination of 5 or less.

In other words, the non-linear polyester used in the present invention and the mold release agent used together prevent the progress of oxidation of the polyester resin, which is relatively easily oxidized during the kneading process in the manufacturing process, and prevent the toner surface from being affected by ozone generated in the copying machine. The progress of oxidation can be inhibited.

When such a toner is used, the progress of oxidation is avoided, which prevents excessive adsorption of moisture onto the toner surface, which prevents a decrease in the amount of charge on the toner and prevents fogging from increasing due to long-term use. It can prevent scattering. Further, since the spread of the charge amount distribution can be suppressed and the fluidity of the toner is not reduced, the developability is also stable and good, and a uniform solid black image can be provided.

Therefore, durability is also improved.

In addition, a decrease in the softening point of the toner is prevented, and the effect spreads to the prevention of toner adhesion and accumulation on the heating roller, the prevention of dirt on the lower roller, and the prevention of dirt on the back surface.

The binder used in the present invention contains a polyester resin, and the polyester is a monomer component containing a trivalent or higher polyhydric alcohol monomer and a monomer component containing a trivalent or higher polyhydric carboxylic acid monomer. Obtained by condensation with components.

Examples of trivalent or higher polyol monomers which are polyvalent monomers according to the present invention include sorbitol, 1.2, 3.
6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2
-Methylpropanetriol, 2-methyl-L2,4-
Mention may be made of butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene, and others.

Examples of trivalent or higher polycarboxylic acid monomers include 1,2,4-benzenetricarboxylic acid and (2).

2.5-benzenetricarboxylic acid, 1.2.4-chlorohexanetricarboxylic acid, 2,5.7-naphthalenetricarboxylic acid, 1.2.4-naphthalenetricarboxylic acid,
(2) 2゜4-butanetricarboxylic acid, L2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenepropane, tetra(methylenecarboxyl)methane, pyrromeliftic acid, 1. 2.
7.8-octanetetracarboxylic acid, cyclohexanetetracarboxylic acid, 1,2.5.6-hexanetetracarboxylic acid, Empol trimer acid, and acid anhydrides thereof,
or lower alkyl esters, and others.

Furthermore, among the less than trivalent monomers involved in the esterification reaction of polyester according to the present invention, examples of diols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol,
．． Diols such as 3-propylene glycol, ■, 4-butanediol, neopentyl glycol, and 1,4-butynediol, Hiss such as 1,4-bis(hydroxymethyl)cyclohexane, hisphenol A, and hydrogenated hisphenol A Phenols, polyoxypropylene (
2,2)-2,2-(4-hydroxyphenyl)propane, polyoquinopropylene (3,3)-2,2-his(
4-hydroxyphenyl)propane, polyoxyethylene(2,0)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene(2,0)-polyoxyethylene(2,0)-2,2 - His(4-hydroxyphenyl)propane, polyoxypropylene (6,0
)-2,2-his(4-hydroxyphenyl)propane and other etherified hisphenols, and other dihydric alcohol monomers.

Dicarboxylic acids include maleic acid, fumaric acid, succinic acid, adipic acid, sebacic acid, malonic acid, itaconic acid,
Examples include derivatives such as ntraconic acid, mesaconic acid, glutaconic acid, nclohexanedicarponic acid, heptatalic acid, isophthalic acid, terephthalic acid, and acid anhydrides or esters thereof.

In the present invention, a polyester resin made non-linear using a monomer having a valence of 3 or more is extremely preferable in terms of anti-offset property, but overall, a component made of a polyvalent monomer of a valence of 3 or more is , 0.1 to 80 mol% in each of the alcohol component or acid component as a structural unit in the polymer, preferably 5 to 80 mol%
The content is preferably 50 mol%. If it is too small, the durability will be poor, and if it is too large, the fixing performance will be poor.

Among the above-mentioned monomer components, benzenetricarboxylic acid is preferably used because it has excellent effects such as fixing properties, anti-offset properties, and triboelectric charging properties.

Further, it is preferable to use etherified phenols as the diol component since they are excellent in offset resistance and durability of the triboelectric developer.

The softening point of the polyester resin of the present invention is 100 to 1500
C is preferable, and if it is less than 100°C, the offset resistance will be poor and if it is more than 150°C, the fixing property will be poor.

Furthermore, the glass transition point of the polyester resin of the present invention is 55
The temperature is preferably 70°C to 70°C, and if it is less than 55°C, the blocking resistance will be poor, and if it exceeds 70°C, the fixing property will be poor.

Further, the acid value of the polyester resin of the present invention is preferably 50 or less, and if it exceeds 50, fogging, toner scattering,
The fixing roller may become heavily soiled.

The polyester resin of the present invention is prepared by mixing a polycarboxylic acid component and a polyol component in an inert gas atmosphere with a concentration of 100 to 250%.
It can be produced by esterification in the temperature range of °C, and dibutyltin oxide] to accelerate the reaction.
Catalysts such as zinc oxide, titanium oxide, tin oxide, etc. may also be used.

Examples of the fixability improver contained in the toner of the present invention include polyolefins, fatty acid metal salts, fatty acid esters and fatty acid ester waxes, partially fatty acidified fatty acid ester class fatty acids, higher alcohols, and liquid or solid paraffin. Wax, amide wax, polyhydric alcohol ester, silicone varnish, aliphatic fluorocarbon, etc. can be used. Among these mold release agents, those having a POV of more than 5 are not included. By using such a fixing property improving agent, the mold release properties are improved and the occurrence of paper clogging in the heat roller fixing device and fixing roller stains can be prevented.

The wax is added in an amount of 05 to 25 wt%, preferably l-10 wt%, based on l.nor.

The toner of the present invention may also contain other resins such as linear polyester, polyamide, polyurethane, Evoquine, styrene, etc.
It may contain a resin such as an acrylic copolymer, but it is preferable that the proportion thereof is 30% by weight or less of the resin.

In the present invention, toner components such as colorants, charge control agents, fixability improvers, magnetic particles, and other property improvers may be dispersed and contained in the toner particles.

All known colorants can be used in the toner of the present invention, such as carbon blank, benzidine yellow, quinacridone, and Locumin B1 phthalocyanine blue.

The magnetic particles used in the toner of the present invention include substances that are magnetized when placed in a magnetic field, such as powders of ferromagnetic metals such as iron, cobalt, and nickel, or magnetite, maghematite, and ferrite. There are compounds. When iron oxide magnetic material is used as a colorant, it may be contained in the toner in an amount of 10 to 80 wt%.

Further, the charge control agent used in the toner of the present invention includes:
Examples include metal complex dyes and nigrosine dyes.

An example of a preferred method for producing the toner of the present invention is to melt and knead the material resin of Hinta or toner components such as a colorant as needed in an extruder, and after cooling. The toner particles are finely pulverized using a jet mill or the like, and then classified to obtain a toner having a desired particle size.

Furthermore, in the toner of the present invention, it is preferable to use iron powder, ferrite powder, and particles whose surfaces are treated with resin, mixed with carrier particles, in order to stabilize triboelectrification. In particular, the use of resin-surface-treated particles as carrier particles is effective in improving the durability of the developer and stabilizing triboelectric charging against environmental changes.

The toner of the present invention further improves fluidity, developability,
It is preferable to mix and use inorganic fine particles that improve transferability.

The primary particle diameter of the inorganic fine particles is preferably from 5 mμ to 2 μm, particularly preferably from 5 mμ to 500 mμ.

In addition, the specific surface area according to the BET method is 2 (1-500 m2
/9 is preferable. The proportion of the inorganic fine particles used is preferably 0.01 to 5% by weight of the toner, particularly preferably 0.01 to 2.9% by weight.

Specific examples of inorganic fine particles include silica, alumina, titanium oxide, barium titanate, cerium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, Examples include cerium oxide, penka, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride. Particularly preferred is a fine powder with good warp strength.

As specific examples of fine silica powder, there are various commercially available products, and those having a hydrophobic group on the surface of the fine particles are particularly preferred.For example, "Aerosil R-972J, [Aerosil R-974J, 805J, Aerosil R-812J (manufactured by Aerosil), Taranox 500J (manufactured by Talco), etc. can be preferably used.

As a method for fixing the toner of the present invention, a hot roller fixing method is preferable, in which the upper roller of the fixing roller is coated with a fluorine-based resin, and the lower roller is made of silicone rubber or a fluorine-based resin coated on the silicone rubber. The relatively soft material is preferable in terms of fixing properties, anti-offset properties, prevention of paper jams, and durability of the roller.

[Synthesis examples and examples]

Next, synthesis examples of representative resins of the present invention and examples of the present invention will be described, but the present invention is not limited to these examples.

° Synthesis example: (1) Binder A ・Polyoxypropylene (2,2)-2,2-bis(4
'-Hydroxyphenyl)furopane 4439.Polyoxyethylene(2)-2,2-his(4'-hydroxyphenyl)propane 1769.Terephthalic acid
1209 Diisopropyl orthotitanate (esterification catalyst) 0.89 or higher was placed in a 1 c round bottom flask equipped with a thermometer, a stainless steel stirrer, a glass nitrogen gas inlet tube, and a falling condenser. Set the flask on a mantle heater, and introduce nitrogen gas from the nitrogen gas introduction tube to keep the inside of the flask in an inert atmosphere until the temperature reaches 23.
The temperature was raised to 0°C, and the reaction was carried out under stirring. When the water produced by the reaction stopped flowing out, the acid value was measured and found to be 1.5.

Furthermore, 1,2,4-benzenetricarboxylic acid anhydride 1399 was added and reacted for about 8 hours, and the reaction was terminated when the acid value reached 17.

The obtained resin is a pale yellow solid, and the softening point of this resin was measured using a flow tester CFT-500J (manufactured by Shimadzu Corporation).
The temperature was determined to be 125°C.

Moreover, pov was 4.5.

(2) Binder B ・Polyoxypropylene (2,2)-2,2-bis(4
'-Hydroxyphenyl)propane 482g, polyoxyethylene(2)-2,2-bis(4'-hydroxyphenyl)propane 126g, 1,6-hexanediol 24g, fumaric acid
174 g of diisopropyl orthotitanate (esterification catalyst) 0.8 g or more of the substance was reacted in the same manner as in the production of binder A, and further,
77 g of 1,2,4-benzenetricarboxylic acid anhydride was added and reacted for about 8 hours, and the reaction was terminated when the acid value reached 22.

The obtained resin is a pale yellow solid, and the softening point of this resin was measured using a flow tester CFT-500J (manufactured by Shimadzu Corporation).
The temperature was determined to be 125°C.

pov was 3.2.

(3) Binder C for comparison The same ingredients as the binder A were reacted under the same conditions, and the properties were different, with an acid value of 15, a softening point of 129°C, and a p o v1.
Binder C of 2.5 was obtained.

201 Examples 1 to 4 and Comparative Examples (1) to (3) (Production of toner) Based on the combinations listed in Table 1 below, 10.0 parts by weight of the binder resin of the synthesis example and carbon black [Mogal After mixing 10 parts by weight of LJ (manufactured by Capo Soto) and 3 parts by weight of 77x, heat at 100 to 130°C using two rollers.
The mixture is thoroughly melted and kneaded, then cooled, coarsely pulverized with a hammer mill, further finely pulverized with a jet mill, and then classified to have a particle size in the range of 3 to 30 μm and an average particle size of 10.0 μm. A sample toner was obtained.

*Polypropylene (manufactured by Sanyo Chemical Industries, Ltd.) (Preparation of developer) A developer was prepared by mixing 4 parts by weight of each of the sample toners and 96 parts by weight of carrier (spherical ferrite particles rF-150j manufactured by Nippon Tetsuko Co., Ltd.). .

The developers obtained in Examples 1 to 4 were referred to as "Developer L".
~ will be referred to as "Developer 4", and the developers obtained in Comparative Examples (1) to (3) will be referred to as "Comparative Developers (1) to (3)".

Photo-copying test> Selenium photoreceptor, magnetic brush developer, upper fixing roller whose surface layer is made of Teflon (polytetrafluoroethylene manufactured by DuPont), and whose surface layer is made of silicone rubber [KE-
1300RTVJ (manufactured by Shin-Etsu Chemical Co., Ltd.), an electrophotographic copying machine r U equipped with a heat roller fixing device consisting of a pull-up lower roller and a cleaning device.
-B 1x-5000J (manufactured by Konica Corporation) was used to conduct a photocopying test using the above developer to form copied images 100,000 times continuously at a temperature of 33°C and a relative humidity of 80%, and the following items were confirmed. Each = 23- <Characteristics measurement> (1) Fog Determined by measuring the relative density of the white background part of the original density of o and o to the copied image using a "Sakuraden/Tometer" (manufactured by Konica Corporation). . Note that the white background reflection density was set to 00. The evaluation is "○" when the relative concentration is less than 0.01.
The case of 0.01 or more and less than 0.03 was marked as "Δ", and the case of 0.03 or more was marked as "x".

(2) Solid black uniformity halftone dot analysis device "Sakura Area Adakku-100J Konica Corp. was used to measure and determine the white ground area ratio in the copied image area corresponding to the black ground area of the original image.

"○" if the white area ratio is less than 5%, 5% or more lO%
If it is less than 10%, mark it as “△”; if it is 10% or more, mark it as “x”.
child.

(3) Toner scattering Visually observe the inside of the copying machine and the copied image, and if there is no visible magnetic toner scattering and it is in good condition, it is marked as "○", and if toner scattering is slightly comparable but at a practical level, it is marked as "○". If there is a lot of toner scattering and there is a problem in practical use, it is marked as 1×.

(4) Visually observe the back side of the copy paper after staining on the back side. Significant stains were rated as ``rx'', those that were slightly stained were rated as ``△'', and those that were not observed at all were rated as ``○''.

(5) Fixing roller stain After 100,000 copies were completed, the heat roller constituting the fixing device was visually observed and determined. The rating is "x" if there is a lot of dirt on the heat roller and it is a practical problem, and "x" if the dirt on the heat roller is slightly comparable but is at a practical level.
△", and when there is almost no dirt on the heat roller, "○"
”.

Note that the melting point in the present invention is measured using a normal melting point measuring device.

In addition, the softening point (Tsp) in the present invention is measured using a 70-chista rCFT-500J (manufactured by Takasu Seisakusho), and the measurement conditions are: load 20, 9/cm2, nozzle diameter 1 mm,
Nozzle length 1 mm% Preheat at 40°C for 10 minutes.
Temperature increase rate 6°C! /min, sample amount 1 cm3
70 - tester plunger descent amount - obtained when measuring and recording (weight expressed as intrinsic specific gravity
The height of the S-curve in the temperature curve (softening flow curve) is h
This is the temperature at h/2.

The acid value in the present invention refers to the number of milligrams of potassium hydroxide required to neutralize the acid contained in Sample 19.

Claims (2)

[Claims] (1) In a non-linear polyester obtained by a condensation reaction of a monomer component containing a trivalent or higher polyvalent monomer as a reaction system component, the non-linear polyester whose peroxide value is 10 or less is used. An electrostatic image developing toner containing a binder. (2) The electrostatic image developing toner according to claim 1, further comprising the releasing agent having a peroxide value of 5 or less.