polyesters having recurring units derived from diols and diacids and recurring units derived from p-hydroxybenzoic acid is disclosed. Electrographic developer compositions comprising toner particles containing the polyesters are also disclosed.
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1. A polyester having recurring units derived from diols and diacids and recurring units derived from p-hydroxybenzoic acid characterized in that from about 15-60 mole percent of the recurring units of said polyesters are derived from p-hydroxybenzoic acid. diacids and diols selected from the group consisting of alkylene glycols and monocyclic diols and recurring units derived from p-hydroxybenzoic acid characterized in that from about 15-60 mole percent of the recurring units of said polyesters are derived from p-hydroxybenzoic acid.
2. A polyester having the following structure: ##STR2## wherein x is about 0 to 100 mole percent of the prepolymer diol component;
y is about 0 to 100 mole percent of the prepolymer diol component; m is about 20 to 100 mole percent of the prepolymer diacid component; and n is about 15 to 60 mole percent of the recurring prepolymer and p-hydroxybenzoic acid units of the polyester.
6. A polyester selected from the group consisting of
poly[poly(ethylene 1,4-cyclohexanedicarboxylate:terephthalate 23:77):1,4-oxybenzoate 75:25]; poly[poly(2,2-dimethyl-1,3-propylene:2,2'-oxydiethylene 80:20 terephthalate):1,4-oxybenzoate 75:25]; poly[poly(2,2-dimethyl-1,3-propylene:2,2'-oxydiethylene 75:25 terephthalate):1,4-oxybenzoate 75:25]; poly[poly(ethylene 1,4-cyclohexanedicarboxylate:terephthalate 29:71):1,4-oxybenzoate 75:25]; and poly[poly(2,2-dimethyl-1,3-propylene:2,2'-oxydiethylene 85:15 terephthalate):1,4-oxybenzoate 75:25].
7. A method of preparing a polyester having recurring units derived from diols and diacids and recurring units derived from p-hydroxybenzoic acid characterized in that from about 15-60 mole percent of the recurring units of said polyesters are derived from p-hydroxybenzoic acid comprising the steps:
(a) forming a prepolymer by (i) heating up to three diols and up to two diacid esters in the presence of a catalyst in an inert atmosphere at about 190°-280°C; (ii) applying vacuum at the temperature range of 260°-280° C.; (iii) continuing to heat under vacuum thereby building up the molecular weight of the prepolymer; and (iv) cooling and isolating the prepolymer (b) reacting the prepolymer with p-hydroxybenzoic acid in the presence of the catalyst used in step (ai) and (c) continuing the reaction until a inherent viscosity of at least 0.3 is reached.
3. The polyester of
5. The polyester in
8. The method of
y is about 0 to 100 mole percent of the prepolymer diol component; m is about 20 to 100 mole percent of the prepolymer diacid component; and n is about 15 to 60 mole percent of the recurring prepolymer and p-hydroxybenzoic acid units of the polyester. and the diols are selected from the group consisting ethylene glycol, 2,2'-oxydiethanol and 2,2-dimethyl-1,3-propanediol and the acids are selected from the group consisting of the esters of terephthalic acid.
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This is a division of application Ser. No. 398,138, filed July 14, 1982, now U.S. Pat. No. 4,416,965.
diols.
Monocyclic diols include 1,4-cyclohexanediol; 1,4-cyclohexanedimethanol; 1,4-cyclohexanediethanol; 1,4-bis(2-hydroxyethoxy)cyclohexane; 1,4-benzenedimethanol; 1,4-benzenediethanol and the like.
Polyalicyclic diols from which the prepolymer may be derived include norbornylene glycol and decahydro-2,6-naphthalenedimethanol.
Useful alkylene glycols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, neopentyl glycol, 2,2,4-trimethyl-1,16-hexanediol, 4-oxa-2,6-heptanediol, 2,2-dimethyl-1,3-propanediol and 2,2'-oxydiethanol.
Useful diacids for the prepolymer include alicyclic, and aromatic dicarboxylic acids or their derivatives, such as esters, and anhydrides, and acid halides. Such acids include succinic acid, sebacic acid; 2-methyladipic acid, diglycolic acid, thiodiglycolic acid, fumaric acid, 1,3-cyclohexane dicarboxylic acid, 1,4-cyclohexane, dicarboxylic acid, cyclopentane-1,3-dicarboxylic acid, 2,5-norbornanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, t-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 4,4'-oxydibenzoic acid, binaphthyldicarboxylic acid, and 9,10-triptycenedicarboxylic acid.
Examples of useful polymers include:
Poly[poly(ethylene 1,4-cyclohexanedicarboxylate:terephthalate 23:77):1,4-oxybenzoate 75:25];
Poly[poly(2,2-dimethyl-1,3-propylene: 2,2'-oxydiethylene 80:20 terephthalate):1,4-oxybenzoate 75:25];
Poly[poly(2,2-dimethyl-1,3-propylene: 2,2'-oxydiethylene 75:25 terephthalate):1,4-oxybenzoate 75:25];
Poly[poly(ethylene 1,4-cyclohexanedicarboxylate:terephthalate 29:71):1,4-oxybenzoate 75:25] and
Poly[poly(2,2-dimethyl-1,3-propylene: 2,2'-oxydiethylene 85:15 terephthalate):1,4-oxybenzoate 75:25].
Useful toner particles of the present invention have an average diameter between about 0.1 micron and about 100 microns, although present day office copy devices generally employ particles having an average diameter between about 1.0 and 30 microns. However, larger particles or smaller particles are useful where desired for particular methods of development or particular development conditions. For example, in powder cloud development such as described in U.S. Pat. No. 2,691,345, issued Oct. 12, 1954, extremely small toner particles on the order of about 0.01 micron are used.
Toner particles are prepared by a variety of known methods. One such method is melt-blending. Melt-blending involves melting a powdered form of the binder polymer and mixing it with other necessary or desirable addenda including colorants such as dyes or pigments. The polymer is melted on heated compounding rolls which are also useful to stir or otherwise blend the polymer and addenda so as to promote the complete intermixing of these ingredients. After thorough blending, the mixture is cooled and solidified. The resultant solid mass is then broken into small particles and finely ground to form a free-flowing powder of toner particles having the desired size.
A variety of colorant materials selected from dyestuffs and/or pigments are advantageously employed in the toner particles of the present invention. Such materials serve to color the toner and/or render it more visible. Of course, suitable toner materials having the appropriate charging characteristics can be prepared without the use of a colorant material where it is desired to have a developed image of low optical density. In those instances where it is desired to use a colorant, the colorants used can, in principle, be selected from the compounds mentioned in the Colour Index, Volumes 1 and 2, Second Edition.
Included among the vast number of useful colorants are such materials as Hansa Yellow G (C.I. 11680), Nigrosine Spirit soluble (C.I. 50415), Chromogen Black ETOO (C.I. 45170), Solvent Black 3 (C.I. 26150), Fuchsine N (C.I. 42510), C.I. Basic Blue 9 (C.I. 52015), etc. Carbon black provides a particularly useful colorant. The amount of colorant added varies over a wide range, for example, from about 1 to about 20 percent of the weight of the polyester binder. Particularly good results are obtained when the amount is from about 1 to about 10 percent.
Other modifying materials such as various long chain anionic or cationic surfactants, conductive materials, and magnetic materials are incorporated, if desired, in the toner particles of the invention. Still other toner additives which are optionally incorporated in the toner particles are materials such as those described in Jacknow et al U.S. Pat. No. 3,577,345, issued May 4, 1971.
The toners of this invention are useful in developing charge images with or without a carrier. When used with a carrier, the carriers are selected from a variety of materials. Suitable carriers useful in the invention include various non-magnetic particles such as glass beads, crystals or inorganic salts such as sodium or potassium chloride, hard resin particles, metal particles, etc. Magnetic carrier particles are also useful in accordance with the invention. Suitable magnetic carrier particles are particles of ferromagnetic materials such as iron, cobalt, nickel, and alloys and mixtures thereof. Other useful magnetic carriers are ferromagnetic particles overcoated with a thin layer of various film-forming resins, for example, the alkali-soluble carboxylated polymers described in Miller U.S. Pat. No. 3,547,822, issued Dec. 15, 1970; Miller U.S. Pat. No. 3,632,512, issued Jan. 4, 1972; McCabe U.S. Pat. No. 3,795,617, issued Mar. 5, 1974; Kasper U.S. Pat. No. 3,898,170, issued Aug. 5, 1975; Belgian Pat. No. 797,132, issued Sept. 21, 1973; and Kasper U.S. Pat. No. 3,795,618, issued Mar. 5, 1974. Other useful resin coated magnetic carrier particles include carrier particles coated with various fluorocarbons such as polytetrafluoroethylene, polyvinylidene fluoride, and mixtures thereof including copolymers of vinylidene fluoride and tetrafluoroethylene.
Another useful carrier comprises a mass of passivated, finely-divided particles of magnetic stainless steel. The carrier particles are prepared from magnetic stainless steel particles of at least 9 weight percent chromium content. The particles are passivated by reaction with nitric acid. This forms a chromium-rich, stable film on the particle surfaces. Before passivation the particles may also be treated, e.g., with hydrofluoric acid, to remove surface silicon. The passivated particles, preferably after thinly coating with a resin, e.g., poly(vinylidene fluoride), are mixed with toner powder for electrographic dry development.
A developer composition containing the above-described toner and carrier particles generally comprises from about 1 to about 40 percent by weight of particulate toner particles and from about 60 to about 99 percent by weight carrier particles. The carrier particles are larger than, or the same size as the toner particles. Carrier particles used in cascade or magnetic brush development have an average particle size on the order of from about 30 to about 1200 microns, preferably 60-300 microns.
The above-described toner and developer compositions are used to develop charge patterns on substrates. The development of charge patterns is carried out by a number of well-known methods. The charge pattern is carried on substrates such as a photoconductive element or a dielectric element. Suitable dry development processes include cascading a cascade developer composition across the electrostatic charge pattern as described in detail in U.S. Pat. Nos. 2,618,551; 2,618,552; and 2,638,416. Another process involves applying toner particles from a magnetic brush developer composition as described in U.S. Pat. No. 3,003,462. Still another useful development process is powder-cloud development wherein a gaseous medium such as air is used as a carrier vehicle to transport the toner particles to the electrostatic charge pattern to be developed. This development process is more fully described in U.S. Pat. No. 2,691,345 and U.S. Pat. No. 2,725,304. Yet another development process is fur brush development wherein the bristles of a brush are used to transport the toner particles to the electrostatic charge pattern to be developed. This development process is more fully described in Walkup U.S. Pat. No. 3,251,706.
As is apparent from the above discussion, the improved electrographic developers containing the toner particles of the present invention preferably comprise various types of carrier vehicles ranging from the conventional inorganic particles used in cascade developers and magnetic particles used in magnetic brush developers to gaseous media and fur brushes used in powder cloud and fur brush developers, respectively.
After development of the charge pattern with the toner particles of the invention, the developed charge pattern is fused as mentioned earlier herein to adhere the toned image to the substrate. If desired, the unfused image is transferred to another substrate such as a blank sheet of copy paper and then fused to form a permanent image thereon. Fixing is generally accomplished by heating the toned image at or above the onset of fusing temperature of the particular polymer from which the toner is formed. Heating of the toned image is carried out with fuser rollers or with radiant heat such as described in U.S. Pat. Nos. 3,666,247; 3,826,892 and 4,118,178. Other heating means such as flash fusing, hot air, or micro-wave are also useful for fusing the toners.
The following examples are provided to further demonstrate the utility and provide a better understanding of this invention. Unless otherwise specified in the examples, the following applies:
1. All inherent viscosities {η} were measured at a concentration of 0.25 g/dl at 25°C in a 1:1 by weight mixture of phenol:chlorobenzene; and
2. the thermal data were measured by differential thermal analysis (DTA) on a DuPont 900 apparatus at a heating rate of 10°C/min with the midpoint of specific heat interval taken as the glass transition temperature (Tg).
This preparation involved two steps. First the preparation of copolyesters without the 1,4-oxybenzoate moiety and then incorporation of 1,4-oxybenzoate units into the preformed polyester.
Step 1
A polyester poly(2,2-dimethyl-1,3-propylene:2,2'-oxydiethylene 50:50 terephthalate) was prepared according to the procedure described in Example 1 of U.S. Pat. No. 4,140,644, issued Feb. 20, 1979 to Sandhu et al., except that a mole ratio of 2,2'-oxydiethanol:2,2-dimethyl-1,3-propane diol of about 0.76:0.68 was used.
Step 2
To the molten solution of preformed poly(2,2'-dimethyl-1,3-propylene:2,2'-oxydiethylene 50:50 terephthalate), (176.4 g, 0.75 mole) I.V. 0.59 dl/g at 285°C under a blanket of nitrogen, with stirring to promote rapid mixing was added 45.0 g, 0.25 mole of p-acetoxybenzoic acid. With the evolution of acetic acid after 15 minutes, a vacuum was applied to the reaction in mixture. The reaction was continued at 285°C/0.05 mm Hg for 2 hours until stirring was very difficult. The reaction mixture on cooling under nitrogen gave a light amber polymer.
A procedure for the preparation of a preformed copolyester from two acids and one glycol and the modification of the preformed copolyester with p-acetoxybenzoic acid is described in this example.
Step 1
Poly(ethylene 1,4-cyclohexanedicarboxylate:terephthalate 29:71)
A mixture of dimethyl 1,4-cyclohexanedicarboxylate (88.1 g, 0.40 mole), dimethyl terephthalate (194.0 g, 1.0 mole), and ethylene glycol (147.7 g, 1.7 mole) in the presence of zinc diacetate dihydrate (0.0629 g) and antimony trioxide (0.158 g) was heated at 200°C under a slow stream of nitrogen overnight until the evolution of methanol ceased. The temperature was increased to 240°C, and the mixture was stirred under reduced pressure (0.025 mm Hg) for 3 hours until the stirring was difficult. The reaction mixture on cooling under nitrogen afforded a water white, amorphous polymer Tg 59°C, I.V. 0.58 dl/g).
Step 2
A reaction between preformed poly(ethylene 1.4-cyclohexanedicarboxylate:terephthalate 29:17)(144.0 g, 0.75 mole) and p-acetoxybenzoic acid (45.0 g, 0.25 mole) under the condition described in Example 1 yielded an off-white, amorphous polymer (Tg 68°C, I.V. 0.33 dl/g).
A series of polyester compositions prepared according to one of the two foregoing methods are set out in Table I.
| TABLE I |
| __________________________________________________________________________ |
| Prepolymer Content (Mole %) Mole % of |
| 100 - (x + y) |
| x y m 100 - m Complete Polymer* |
| Polymer |
| Ethylene |
| 2,2-Dimethyl- |
| 2,2'- Terephthalic |
| 1,4-Cyclohexane- |
| p-Hydroxy benzoic |
| No. Glycol 1,3-Propanediol |
| Oxydiethanol |
| Acid dicarboxylic Acid |
| Acid |
| __________________________________________________________________________ |
| Control 1 |
| 0 80 20 100 0 0 |
| Control 2 |
| 1 100 -- -- 83 17 25 |
| 2 100 -- -- 77 23 25 |
| 3 100 -- -- 71 29 25 |
| 4 100 -- -- 67 33 25 |
| 5 100 -- -- 62 38 25 |
| 6 -- 100 -- 100 -- 25 |
| 7 -- 90 10 100 -- 25 |
| 8 -- 85 15 100 -- 25 |
| 9 -- 80 20 100 -- 25 |
| 10 -- 75 25 100 -- 25 |
| 11 -- 70 30 100 -- 25 |
| 12 -- 60 40 100 -- 25 |
| 13 -- 50 50 100 -- 25 |
| 14 -- 20 80 100 -- 25 |
| 15 -- 50 50 100 -- 25 |
| 16 -- -- 100 100 -- 25 |
| __________________________________________________________________________ |
| *NOTE- |
| The polymers of Table I consist of a "prepolymer" further polymerized wit |
| Phydroxy benzoic acid. Hence, polymer composition on mole percent basis |
| equals total moles of prepolymer plus total moles of phydroxybenzoic acid |
The polymers of Table I were evaluated for inherent viscosity, glass transition temperature (Tg), and grindability. The onset of fusing and hot offset temperatures were also determined to establish fusing latitude.
Grindability was tested by feeding coarsely ground toner granules into a Trost TX Jet Mill (available from Garlock Co., Plastomer Div., Trost Mill Dept.) at a rate of about 15 grams per hour. The mill was operated at a pressure of about 70 lbs./sq. inch (4.92 Kg/cm2) with compressed air. Grindability of the material tested was considered acceptable if at least 75% of the ground particles possess a size of less than 25 microns. The toners were prepared according to the melt-blending procedure previously described herein.
The onset of fusing and the hot offset temperatures were determined as follows. Deposits of toner, applied to paper by means of a tissue or camel hair brush, were fixed to the paper by means of a roller fuser. The contact roller fuser consisted of an internally heated compliant fusing roll and a non-compliant pressure roll. The former was covered with about 50 mils of Eccosil® 4952 (Emerson-Cuming Co.), the latter with Teflon® FEP (DuPont). The two rolls were engaged at a pressure of 15 pounds per linear inch. The surface speed of the rolls was 10 inches per second. A very slight amount of Dow Corning DC 200 fluid (60,000 cp) was applied to the fuser roller. Images were fused in this system at varying temperatures to establish the minimum temperature for good fusing and the temperature at which hot offset occurred on the fuser roll. The minimum temperature (onset of fusing) for fusing is defined as the temperature at which the crack resulting from folding the paper in the toned area is less than 0.2 mm while the toner is not completely removed from the cracked area.
The following results were obtained.
| TABLE II |
| ______________________________________ |
| Onset of |
| Hot Fusing |
| Example |
| Polymer Grind- Fusing, |
| Offset, Latitude, |
| No. No. ability °F./°C. |
| °F./°C. |
| °F./°C. |
| ______________________________________ |
| Control |
| Control 1 no Not Not Not |
| Tested Tested Tested |
| 3 1 yes 275/135 |
| 325/163 50/28 |
| 4 2 yes 267/131 |
| 350/177 83/46 |
| 5 3 yes 250/121 |
| 325/163 75/42 |
| 6 4 yes 237/114 |
| 300/149 63/35 |
| 7 5 yes 250/121 |
| 300/149 50/28 |
| 8 6 yes Not Not Not |
| Tested Tested Tested |
| 9 7 yes 287/142 |
| 375/191 88/49 |
| 10 8 yes 275/135 |
| 400/204 125/69 |
| 11 9 yes 275/135 |
| 400/204 125/69 |
| 12 10 yes 262/128 |
| 400/204 138/76 |
| 13 11 yes 262/128 |
| 350/177 88/49 |
| 14 12 yes 237/114 |
| 350/177 113/63 |
| 15 13 yes 212/100 |
| 300/149 88/49 |
| ______________________________________ |
The data of Table II shows that Examples 3-15 of Table I possess acceptable grindability whereas the grindability of the control polymer is unacceptable. The data of Table II also shows that the polyesters of the present invention provide polyester materials which form toners having a good fusing latitude.
This invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.
Molaire, Michel F., Wright, John F., Sandhu, M. Akram
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