Recording apparatus and ink employing biodegradable substance

RECORDING APPARATUS AND INK
EMPLOYING BIODEGRADABLE
SUBSTANCE

This application, is a division of application Ser. No. 08/203366,'filedMar. 1,1954, new U.S. Pat No, 5,579,038.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a recording apparatus which intends to prevent environmental pollution, particularly to a biodegradable waste-ink absorbent of the environment protection type which will not cause environmental pollution, and is effective in absorbing a. waste aqueous dye-containing ink in ink-jet recording apparatus such as printers, copying machines, and plotters for recording letters and images.

The present invention also relates to an ink-jet: recording apparatus employing the above waste-ink absorbent

Trie present invention farmer relates to an ink which will not cause environmental pollution and is useful for writing tools such as felt-tip pens, ball-point pens, and line-markers; printers for recording letters and images, copying machines, facsimile machines, plotters, and particularly ink-jet recording apparatus.

The present invention former relates to an apparatus employing the above ink.

2. Related Background Art

Hitherto, in ink-jet recording and related technical fields employing an aqueous dye-containing ink, improvement of weatherability of the ink such as lightfastness, water resistance, and ozone resistance have been studied to prevent natural deterioration of inks. Therefore, various efforts have been made to improve weamerability of the dye itself for the ink, namely the coloring matter of the ink.

For example, the number of soiubllizing groups (e.g., —OH, —S03, —COOH, etc.) in a dye molecule is decreased to raise water fastness of the dye. Such dyes are stable in a relatively high pH range because of their lower water-solubility, but tend to deposit at a pH of environmental water (pH=5.8 to 8.6). Accordingly, the dye, if discharged to the environment, is liable to deposit and accumulate in the soil, or bottoms of rivers, lakes or seas and color the ecosystem therein.

On the other hand, with increasing volumes of color image recording in recent years, high color-developing inks ace coming to be consumed in a larger quantity. The consumption of water-based color inks is increasing year by year particularly in ink-jet recording and in general writing. Especially, high color-developing dyes, which give high quality recorded images, are expected to be used a greater extent Ideally, the aforementioned aqueous ink charged in the recording apparatus is to be used only for recording. Practically, however, not all of ink is consumed entirely by the recording, but the ink is partly recovered by a built-in mechanism called a recovery system to secure the reliability of the recording apparatus.

This recovery system serves at the start of recording to suck out a part of ink from the recording head and replace it: with fresh ink to facilitate the start of recording after a long term, of standing of the recording head. The ink sucked out by this step is sent through a waste ink transfer path and stored as a waste ink in a container having an ink absorbent The absorbent which has absorbed the waste ink to its full capacity is discarded or burnt, by itself or together with the

container. With increased use of the ink-jet recording; system, the amount of the discarded waste-ink absorbent and the discarded container thereof is expected to further increase.

5 Few of the color-recorded materials prepared with the aforementioned coke ink are preserved for a long; term, but most of them typically are used only for temporary purposes. In other words, most of the recorded matters are discarded into the environment The water-based color ink which has

10 been discharged into the environment rarely deposits in the soil or on the bottom of bodies of water. The ink discharged onto the soil will cause coloring and contamination of underground water. The ink discharged into waters also will cause coloring and contamination which decreases light

15 transmittance of the waters and destroys the fishery ecosystem by causing water-bloom growth.

SUMMARY OF THE INVENTION

,20 The present invention intends to provide a biodegradable ink absorbent, and is effective in environmental protection to meet the increasing amount of the discarded waste-ink absorbent which may he thrown away into the environment. The present invention also intends to provide an ink-jet

25 recording apparatus which employs the above ink absorbent The present: invention further intends to provide an ink containing a biodegradable dye which will be degraded by inicroorganisms into safe substances with decolonization, and has excellent recording properties and high water fast

30 ness.

The present: invention still further intends to provide an ink-jet recording method, and an ink-jet recording apparatus employing the above ink. According to an aspect of the present: invention, there is ,3'5 provided a waste-ink absorbent to be mounted on an ink-jet recording apparatus, comprising a composition containing a biodegradable polymer and. a microorganism growth nutrient.

w According to another aspect of the present invention, there is provided an ink-jet recording apparatus equipped with a waste-ink absorbent, wherein the waste-ink absorbent is comprised of a composition containing a biodegradable polymer and a microorganism growth nutrient.

45 According to still another aspect of the present invention, there is provided an ink containing a recording agent: and a liquid, medium for dissolving or dispersing the recording agent, the recording agent comprising a composition containing a biodegradable polymer linked to a solobilizing

sn group of a water-soluble dye by cocjrdination bonding. The biodegradable polymer in the ink may be an organic acid salt of cationic chitosan or cationic starch, Further, the biodegradable polymer may be contained in an amount of from 1 to 30% by weight based on the water-soluble dye.

55 According to a further aspect of the present invention, there is provided an. ink-jet: recording method which conducts recording by ejecting droplets of an ink containing a recording agent and a liquid medium for dissolving or dispersing the recording agent through an ejection orifice of

6o a recording head in correspondence with recording signals, the recording agent comprising a composition containing a biodegradable polymer linked to a solubilizing group of a water-soluble dye by coordination, bonding. According to a further aspect of the present invention,

65 there is provided a recording unit equipped with an ink container holding an ink therein and a head far ejecting droplets of the above-mentioned ink.

3

According to a Anther aspect of the present invention, there is provided an ink cartridge equipped with an ink container holding lite above-mentioned ink.

According to a Anther aspect of the present invention, there is provided an ink-jet recording apparatus equipped with a recording unit having an ink container holding an ink therein and a head for ejecting droplets of the abovementioned ink.

According to a further aspect of the present invention, there is provided an ink-jet recording apparatus equipped with a head for ejecting an ink as droplets, an ink cartridge having an ink container holding the ink therein, and an ink supplying device for supplying the above-mentioned ink from the ink cartridge to the head

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of an ink-jet recording head along an ink flow path direction.

FIG. 2 is a front view of the ink-jet recording head at the cross-section A-B.

FIG. 3 is a perspective view of an example of an entire ink-Jet recording apparatus.

FIG. 4 is. a cross-sectional view of an example of an ink cartridge.

FIG. 5 is a perspective view of an integral construction of an ink-jet recording head and an ink cartridge.

FIG. 6 illustrates schematically the state of biodegradation of a specimen of a waste ink absorbent

FIG. 7 illustrates schematically flue test method in Examples 5 to 9 of the present invention and Reference Examples 1 to 2,

FIG. 8 is a graph showing the evaluation results in Examples 5 to 9 of the present invention and Reference Examples 1 to 2.

DETAILED DESCRIPTION OF THE
PREFERRED EMBODIMENTS

The ink- jet recording apparatus of the present invention is characterized by the ink absorbent which comprises a composition containing a biodegradable polymer and a microorganism growth nutrient The present invention .is further characterized in that not only the biodegradable substance is utilized by itself but also the biodegradation is intentionally made to proceed advantageously from the start of the use in consideration of the long period, several months to several years, required for the biodegradation.

In other words, the ink absorbent of the present invention, is especially characterized in that the absorbent and the ink absorbed thereto begin to decompose due to growth of microorganisms at the time when they axe used in the apparatus.

Furthermore, the present invention is also characterized by an ink-absorbent container which is constructed from a plastic material containing a minimum amount of an antimicrobial agent to prevent decomposition and collapse of the waste ink absorbent during the time when the absorbent is mounted on the apparatus and the function of title apparatus is utilized.

The present invention pnovid.es an ink which contains a recording agent and a liquid medium for dissolving or dispersing the agent, the recording agent comprising a composition having a biodegradable polymer linked by coordination bonding with a solubilizing group of the watersoluble dye, and provides also an ink-jet recording method, and an apparatus employing the ink.

4

The waste-ink absorbent employing a biodegradable polymer, which is a first embodiment of the present: invention, is described first

'The biodegradable polymer employed in the present 5 invention; which will decompare in a light-intercepting ink absorbent: container, is suitably a. biodegradable synthetic polymer. The effective biodegradable synthetic polymer includes:

(1) starch-compounded polymers,

(.2) modified starch-compounded polymers,

(3) micronized cellulose-compounded polymers, and

(4) microorganism-produced synthetic polymers.

In some cases, polymers mentioned below may be used 15 although fhey are somewhat less biodegradable:

(5) polycaprolactone-conipounded polymers, and

(6) PEG, PVA, polyurethanes, and polyesters.

The antimicrobial agent to be incorporated in the container of the waste-ink absorbent is suitably a usual imldew

20 proofing agent for plastics, specifically including preventole ^-fluorc4icUoromemylmiophthalimide), thiabendazole, Na-omadine, dioxin, and so forth.

The microorganism-growth nutrient to be mixed with the biodegradable polymer is required, to become useful as a

25 nutrient for the microorganism only when it is brought into contact with water which is a main constituent of the ink. The suitable niicroorganisam-growth nutrient includes powdery solid foodstuff's, starch, sugars, and the like. Such a powdery natter is incorporated into the aforementioned

30 absorbent constituted of a biodegradable polymer to cause growth of microorganisms.

No evaluation method is clearly defined for the biodegradabllity of the ink absorbent having the above constitution. One example of applicable evaluation methods therefor

35 is a method shown in ASTM G21-70. In this evaluation method, the growth degree of microorganism (mildew) is raited, on grades by comparison with a polystyrene resin, and. a polyethylene resin as .reference samples. In this evaluation, the growth degrees on the reference resins (polystyrene and.

40 polyethylene) correspond to the first grades and the second grades, and the growth degree on the test sample which is defined to have biodegradability corresponds to the third or fourth grade.

Another method of reflecting generally the biodegradabil

45 ity in a natural environment in a. broad sense is the microorganism-degradation test (so-called MtTI test) of various chemical substances based on "Law Concerning the Examination and Regulation of Manufacture, etc. of Chemical Substances'" enforced iin Japan in 1974. In title MtTI test,

so activated sludge is employed which participates in. natural cleaning. For the intention, of the present invention, it is considered suitable to apply the evaluation method of the above ASTM G21-70 test' From the standpoint of environmental pollution

55 prevention, not only the ink absorbent, but also other parts including the outer case of the recording apparatus, the ink container, and other material, which have previously been constructed from a non-rotting substance, are desirably constructed from a biodegradable or photodegradable mate

60 rial as far as possible.

In an example of ink-jet recording apparatus employing the aqueous ink of the present invention, thermal energy is applied to the ink, and droplets of the ink are ejected, by bubbling caused by the thermal energy to conduct recording.

65 An ink-jet recording head which is a main part of 1he apparatus has a construction, for example, as shown in FIG. 1 and FIG. 2. FIG. 1 is a sectional view of the .ink-jet recanting head along an ink flow path direction. FIG. 2 is a front view of the head.

In FIG. 1, the head 1.3 is constructed by bonding a plate of glass, ceramics, or plastics having grooves 14 for ink flow

21 with a head base plate 15 having a heat-generating 5 portion. The base plate IS of the heat-generating head is constituted of a protection layer 16 formed of silicon oxide or the like, electrodes 17 made of aluminum or the like, a heat-generating resistance layer 18 made of hafnium boiide

or me like, a heat accumulating layer 19 made of silicon 10 oxide or the like, and substrate plate 20 made of alumina or the like.

On application of an electric signal to the electrodes 17 of the head, the region denoted by a symbol "h" on the head base plate 15, namely the heater region, generates heat is abruptly to form bubbles in the ink 23 in contact with the beater region, and ink droplets 24 are ejected from an ejection nozzle 22 by the pressure of the bubbles. The ink droplets ejected from, the head are projected toward a recording medium 25 to form a recorded image. The ink-jet 20 recording head 13 may have a plurality of ejection nozzles

22 in correspondence with the intended recording density. FIG. 3 illustrates an example of the Ink-jet recording

apparatus having such a head mounted thereon. In FIG. 3, a blade 61 as a wiping member is held at one end by a 25 blade-holding member, forming a fixed end in the shape of a cantilever. 'The blade 61 is placed at a position, adjacent to the recording region of the recording head, and is constituted such that it moves in the direction perpendicular to the direction movement of the recording head to come into 30 contact with the ejection nozzle face to cap the nozzles.

An ink absorbent 63 is placed at a position adjacent to the blade 61, and is held so as to protrude into the path of motion of the recording head in a manner similar to that of the blade 61. The ink absorbent 63 is connected through a tube or the 35 like to a waste-ink absorbent 99. The blade 61, the cap 62, and the absorbent 63 serve to remove water, dost, and the like from the face of the ink ejection nozzle.

A recording head 65 has an energy-generating means for the e jection, and conducts recording by ejecting the ink onto 40 a recording medium, opposite to the ejection nozzle face. A carriage 66 is provided for supporting and moving the recording head 65. The carriage 66 is engaged sHdably with, a guide rod 67. A portion of the carriage 66 is connected (not shown in the drawing) to a belt 69 driven by a motor (58, so 45 that the carriage (5* is movable along the guide rod 67 to the recording region of the recording head. 65 and the region adjacent thereto.

A paper delivery portion 51 for delivery of a recording medium and a paper delivery roller 52 driven by a motor 50 (not: shown in the drawing) delivers a recording medium to the position opposite to the ejection nozzle face of the recording head, and the recording medium is delivered with the progress of the recording to a paper discharge portion provided, with paper-discharging rollers 53. 55

In the above constitution, when the recording head 65 retains to the home position on completion of recording, the cap 62 of the head-recovery portion 64 is positioned out of the path of movement of the recording head 65, and the blade 61 is allowed to protrude into the path of movement 60 Thereby, the ejection nozzle face of the recording head 65 is wiped. To cap the ejection face of the recording head 65, the cap 62 protrudes toward the path of the recording head to come into contact with the ejection nozzle face.

When the recording head 65 is made to move from the 65 home position to the record-starting position, the cap 62 and the blade 61 are at the same position as in the above:

6

mentioned wiping step, so that the ejection nozzle face of title recording head, is wiped also in this movement The recording head, is moved to the home position not only at the end of the recording and at the time of ejection recovery, but also at predetermined intervals during recording in the recording region. The nozzle is wiped by such movement

FIG. 4 is a sectional view of an example of the ink cartridge 45 which holds an ink to be supplied through an ink supplying member such as a tube. The ink container portion 40, far example an ink bag, contains an ink to be supplied, and has a rubber plug 42 at: the tip. Insertion of a needle (not shown in the drawing) into the plug 42 enables supply of the ink from, the ink bag. A waste ink absorbent 44 serves to absorb a waste ink. The liquid-contacting surface of the ink container portion is preferably made of poly olefin, particularly preferably made of polyethylene.

The ink-jet recording apparatus used, in the present invention is not limited to the above-mentioned one which has a head separate from an ink cartridge. Integration thereof as shown in FIG. 5 may suitably be employed. In FIG. 5, a recording unit 70 houses an ink container portion including an ink absorbent, and the inkin the absorbent is ejected from a head 71 having a plurality of orifices. An aircommunication opening 72 is provided to communicate the interior of the cartridge with the open ak. The recording unit 70 may be used, in place of the recording head shown in FIG. 3, and. is made to be readily mountable to and demountable from the carriage 66.

The ink containing a biodegradable polymer, which is a. second embodiment of the present invention, is described below.

The ink of the present invention comprises a composition containing a biodegradable polymer linked to a watersoluble dye at the solubilizmg group of the dye by coordination bonding.

The water-soluble dye generally has a structure in which two or more naphthalene rings car benzene rings are linked through am azo group or azo groups, and a hydroxy group, an amino group, a sulfo group, or the like is linked thereto, for example, as shown, below.