JPS59209876A - Liquid-supplying device - Google Patents

Abstract

PURPOSE:To enable to stably maintain for a long period of time the characteristic of supplying a liquid such as an ink, by a method wherein a surface region on a liquid-jetting part side of a cap member or a proximate region on the inside of the surface is constituted of an ester base urethane rubber. CONSTITUTION:A cap roll 10 comprises a metallic core 17 made of Al or the like at the periphery of a rotary shaft 16, and an elastic layer 18 consisting of an ester base urethane rubber is integrally provided around the entire periphery of the core 17. Since the surface layer 18 of the roll 10 consists of the ester base urethane rubber, a residual part of an ink column C ejected from a nozzle 6 can be easily attracted to the roll 10 side. In addition, since the roll has an appropriate surface hardness and appropriate elasticity, the roll 10 is elastically returned from a deformed condition to an original shape after parting from the nozzle 6, so that it can be sufficiently cleaned subsequently, and can sufficiently endure friction by a cleaning blade 12.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Field of Industrial Application The present invention relates to a liquid supply device, and particularly to an ink supply device suitable for an inkjet printer.

2. Prior Art Conventionally, an inkjet printer records desired characters or figures on a recording material such as recording paper without applying impact, and the nozzle opening of the recording ink jetting nozzle is closed with a cap roll when not in use. There are known printers that allow this. Unlike conventional impact-type recording devices, these inkjet printers obtain a desired information pattern by causing controlled recording ink droplets to collide with a recording material, and are used by an output recording device such as a computer or typewriter. It has reached the point where it has been put into practical use.

In such a printer, the nozzle (hereinafter, the unit including the nozzle is referred to as a print head, and the part that ultimately ejects recording ink is referred to as a nozzle) has an ink ejection opening (nozzle opening) that is in contact with the outside air. have. In this case, even if the nozzle is located inside the device,
It is inappropriate to leave it as it is when not recording.

This is because, if left in this state, dust particles may adhere to the nozzle portion, or air bubbles may form or dry in the nozzle portion, which may cause the recording operation to be interrupted.

In particular, if dust (fine particles) adheres to the nozzle opening, a portion of the ejected ink will collide with the dust, making it impossible to maintain the constant amount of ink during flight. Moreover, in an apparatus in which straightness of ejected ink is essential, the above-mentioned phenomenon has the undesirable effect of forming dots at unexpected locations on the recording material and destroying the recorded image. Further, the ejected ink that collides with the adhered dust travels over it and contaminates the front surface of the print head. In this case, if the print head is equipped with a plurality of nozzles (for example, seven nozzles in the vertical direction), the spacing between the nozzles is extremely small, which will adversely affect other nozzles. In other cases, the collided ink solidifies on the dust, and when it becomes large, it causes a condition in which the nozzle opening is blocked, making it no longer possible to perform a recording operation.

Next, the generation of bubbles and the undesirable consequences thereof will be discussed. Although the nozzle opening is extremely small, recording ink is made up of volatile substances whose main components are, for example, ethylene glycol, water, and pigments, so if non-recording operations are continued for a long time, they will vaporize little by little, causing the inside of the nozzle to leak. Air is introduced into the

Furthermore, air also enters the nozzle when environmental changes occur, especially temperature changes. For example, when the temperature decreases, the ink in the Nayanba provided in the print head (including the nozzle portion, of course) contracts as described above. At this time, since the opening of the print head exists only in the nozzle part, the ink surface inside the nozzle is pulled back inside the chamber,
As a result, air is introduced. Although this amount of contraction is small in absolute value, the volume of the nozzle is even smaller, so even the slightest change as described above will cause air to enter. The air that has entered the nozzle in this way is trapped by the movement of the ink and becomes bubbles. Also, when the ink inside the nozzle evaporates,
If some pigment is left behind in the nozzle and hardens, this causes bubbles to be generated during the next operation. Additionally, if the printhead is accidentally subjected to a sudden shock or vibration, ink may be ejected from the nozzles, also causing bubble formation. In any case, when a bubble generated for some reason reaches the chamber, the kinetic energy associated with the volume conversion for ink droplet ejection based on the aforementioned control signal is used to contract the bubble, and the ink is ejected. will no longer be able to contribute to It is understood without needing explanation that this is a fatal flaw.

In order to correct the above-mentioned problems, when the print head performs a recording operation, the print head is kept at a distance from the nozzle provided at the tip of the print head, and after the recording operation is completed, the print head stops at a predetermined position. By arranging camping means so as to be able to come into contact with the nozzle and cover its opening after the recording is performed, it is possible to prevent dust from landing on the nozzle part during non-recording time, and also to prevent dust from landing on the nozzle part due to changes in the environment. An inkjet printer has been proposed that can eliminate the occurrence of air bubbles from the nozzle.

As the cap means used in this printer, a cap roll made of an elastic material is known. This cap roll is pressed against the nozzle opening when not recording, and its elastic bite tightly closes the nozzle opening from the outside air, so it can achieve the above-mentioned advantageous effects, but it also has the following effects: It is necessary to have good performance at the same time.

(1) It must have appropriate elasticity to sufficiently close the nozzle opening.

(2) The roll surface is hydrophilic. That is, while the ink is hydrophilic, the nozzle is configured to be hydrophobic, so if the cap roll is hydrophobic, some of the ink will remain on the head side when the cap roll is removed from the nozzle.

Furthermore, when the cap roll is removed from the nozzle, the ink is repelled by the surface of the roll and falls.

(3) Must have durability. That is, the cap roll is separated from the nozzle after the nozzle opening is closed, and the ink adhering to the surface of the cap roll is scraped off by a cleaning unit (for example, a cleaning blade) as described later.

At this time, the cap roll is required to have creep resistance (no distortion such as permanent deformation) and abrasion resistance (to withstand wear caused by the cleaning member).

(4) The surface is a mirror surface. The surface of the cap roll must have excellent cleaning properties, that is, be mirror-finished so that no ink remains on the camp roll during the above-mentioned cleaning.

As a result of studies on conventional cap rolls, the inventor found that among the required performances (1) to (4) above, known cap rolls have particularly poor durability and insufficient hydrophilicity. I figured it out. For example, JP-A-54-
The camp roll made of polyurethane rubber disclosed in Japanese Patent No. 68633 has a lack of durability peculiar to polyurethane rubber, and the hydrophilicity of the urethane bonding portion is not very high.

3. OBJECTS OF THE INVENTION An object of the present invention is to provide an apparatus that can maintain stable supply characteristics of liquids such as ink over a long period of time and that satisfies all the performance requirements of camp shrines.

4. Structure of the Invention In other words, the liquid supply device according to the present invention includes a liquid ejection part (e.g., an ejection nozzle) that ejects and supplies liquid such as ink, and a liquid ejection part that presses the ejection port when the liquid ejection part is not in use. and a camp member which is closed by the user, and at least the surface area of the camp member on the side of the liquid jetting part, or at least the vicinity area inside the surface of the camp member is made of ester-based urethane rubber. .

5. Examples Hereinafter, the present invention will be described in detail with reference to examples.

FIG. 1 is a perspective view showing the configuration of the printer, and FIG. 2 is a sectional view thereof.

A recording paper P is wound around the platen 1. Further, the paper press roller 4 biased by the tension spring 2 and the paper press roller 5 biased by the tension spring 3 come into pressure contact with the platen 1 to bring the recording paper P into close contact with the platen 2. platen l
is rotated by a motor or the like (not shown) and conveys the recording paper P.

A print head 7, which has an ink jet nozzle surface 6, is mounted on a carriage 8 and is driven by a wire (not shown) and a motor (not shown) connected to the carriage 8.
Arrow A along carriage shafts 9a, 9b that mate with
, move in direction B.

Ink is ejected from the ink ejection nozzle surface 6 toward the recording paper P in accordance with a recording signal to perform printing on the recording paper P.

In order to obtain good printing on the paper P, it is necessary to perform ink jetting in a stable manner.
+ c It is obtained by holding this. For this reason, in this printer, the carriage 8 is
A gap roll 10 provided in the axial direction of the platen 1
The ink jet nozzle surface 6 and the outer circumferential surface of the camp roll 10 are brought into close contact with each other. FIG. 3 shows a cross-sectional view of this state.

In this case, the noteworthy structure is that the camp roll 10 has a core metal 17 made of AI or the like around the rotating shaft 16, and an elastic layer 18 made of ester-based urethane comb is integrally provided around the entire circumference of the core metal. That is what we are doing. Nozzle 6 as shown in Figure 3
When the nozzle 6 is not in use (not recording), the tip opening of the nozzle 6 (
In order to close the ink jet ports 19, the cap roll 10 is pressed as shown in an enlarged view in FIG.

At this time, since the roll surface layer is made of ester-based urethane rubber, it elastically bites into the nozzle 6 while being in close contact with the nozzle 6, completely blocking the injection port 19.

For example, the cap roll 1o is 300g for the nozzle 6.
/cm is pressed, and the amount of penetration at this pressing is 0.6m
It can be about m.

The urethane comb that is the constituent material of the elastic layer 18 differs from ordinary urethane combs in that it contains ester groups within its molecules.

Because it is an ester-based product, it not only has appropriate softness, but also has appropriate rubber hardness and hydrophilicity, which are factors that can fully meet the various performances required for cap rolls. . In particular, the rubber hardness maintains the mechanical strength or durability of the elastic layer 18, which can be achieved by appropriately selecting the constituent components of the polyurethane described below. Desirable rubber hardness is JIS standard (A)
The rubber hardness is 20 to 60, more preferably 25 to 55, and most effective 30 to 50. If the rubber hardness exceeds 60, the pressure applied to the head when pressing the head 6 will be unnecessarily large, and if it is less than 20, it will be too soft and difficult to harden during manufacturing. The camp roll 10 can be manufactured by placing a core metal 17 previously molded by die-casting or the like in a mold, injecting a urethane rubber component composition into the molding space, and curing it. in this case,
By applying an adhesive to the outer peripheral surface of the core bar 17 in advance or roughening the outer circumferential surface to an appropriate degree, the adhesive strength of the elastic layer 18 to the core bar 17 can be increased.

Further, the outer circumferential surface of the elastic layer 18 is preferably finished to have a surface roughness of 1.0 μs or less (preferably a mirror surface) in order to improve cleaning performance during cleaning, which will be described later. In order to achieve this, a band-shaped metal ring with a small surface roughness may be placed at a position corresponding to the outer peripheral surface of the elastic layer 18 during the above-described molding.

On the other hand, the ink ejection nozzle surface 6 is treated to be a surface that repels ink. For example, when using water-based ink, the ink ejection nozzle surface 6 may be subjected to a water-repellent treatment. When ink is ejected from the ejection nozzle surface 6, an ink column C is formed between the ink ejection nozzle surface 6 and the cap roll 10 as shown in FIG.

At this time, the overflowing ink flows into a purge nozzle 11 connected to a suction pump (not shown). Ink column C
is formed, turn the cap roll 10 counterclockwise (arrow)
When the ink column C is rotated in the direction, the ink column C moves to the lower side of the ink jet nozzle surface 6 and is attracted by the purge nozzle 11, so that the ink jet nozzle surface 6 becomes clean.

The ink that cannot be completely sucked into the purge nozzle 11 by these operations tends to adhere to the outer peripheral surface of the cap roll 10, which has good hydrophilicity, and the adhered ink is made of synthetic materials such as polyacetal that come into contact with the outer peripheral surface of the cap roll 10 as the roll 10 rotates. The ink scattered and scraped off by the resin doctor blade 12 is absorbed by the pad 13, and the outer peripheral surface of the cap roll 10 is cleaned.

If there is ink remaining on the outer peripheral surface of the camp roll 10, the ink dries and solidifies. This solidified ink clogs the ink ejection port 19 (see FIG. 4) of the ink ejection nozzle surface 6 and has an adverse effect. Therefore, the outer peripheral surface of the cap roll 10 must always be kept clean. For this purpose, the above-mentioned cleaning device consisting of the doctor blade 2 and the pad 13 has a structure in which the cleaning device is brought into pressure contact with the circumferential surface of the cap roll 10 by a compression spring 15 utilizing the wall surface of the roll cover 14.

As is clear from this l)1 cleaning device, the surface J-18 of the cap roll 1 ( ) is made of ester-based urethane comb, so the remaining part of the ink column C is removed from the nozzle 6 as shown in Figure 5. is easily adsorbed to the roll 10 side.Furthermore, since the roll 10 has appropriate surface hardness and elasticity, it elastically returns to its original shape from its deformed state after being separated from the nozzle 6. This allows the next cleaning to be carried out sufficiently, and the cleaning plate 12
The structure is designed to withstand wear and tear.

Next, examples of the ester-based urethane rubber that is the constituent material of the elastic layer 18 of the camp roll 10 described in "2" include those that can be synthesized by a reaction between a polyol and polyisocyanate-1. Examples of I″iJ-capable polyols used here include phthalic acid, adipic acid, trimerized lyluic acid,
Organic dibasic acids such as maleic acid, glycols such as ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, or 1-limerol propane, hexanetriol, glycerin,
h A polyester polyol synthesized by reacting two or more arbitrary polyols selected from polyhydric alcohols such as limethylolpropane, hexanetriol, chrycerin, trimethylolethane, and pentaerythritol with a carboxylic acid; or , S-prolactam, α-methyl-1-prolactam, S-me, Chiru 8
- There are rough polyester polyols synthesized from lactams such as caprolactam and γ-butyrolactam.

The carboxylic acids to form the polyester include malonic acid, maleic acid, succinic acid, adipic acid, glycuric acid,
Pimelic acid, sebacic acid, oxalic acid.

The above polyester polyols include tolylene diisocyanate-1 to hexamethylene diisocyanate, methylene diisocyanate, meta-xylylene diisocyanate.
It is reacted with isocyanate compounds such as 1., thereby synthesizing urethanized polyether polyurethane and polyether polyurethane. These polyurethanes are usually produced primarily by the reaction of polyisocyanate-1 with polyols and also in the form of urethane resins or urethane prepolymers containing free isocyanate groups and/or hydroxyl groups, or in the form of urethane prepolymers containing reactive end groups of these. (for example, in the form of a urethane elastomer).

Since polyurethane, urethane prepolymer, methods for producing urethane elastomer 7-, curing and crosslinking methods, etc. are well known, detailed explanation thereof will be omitted.

As mentioned above, the ester-based urethane rubber (polyurethane) can be synthesized from a polyol having two or more active hydrogens and a polyisocyanate 1- having two or more isocyanate groups, but by selecting each reaction component. The physical properties of the urethane rubber, such as hardness and elasticity, can be adjusted as appropriate, and the hydrophilicity of the rubber can also be controlled as desired by the ester moiety. This urethane rubber also contains polyfunctional active hydrogen compounds such as water, hydrogen sulfide, dimethyl captan, dicarboxylic acids, amino alcohols, glycols,
Crosslinking with diamine or the like further improves mechanical strength.

Moreover, as the above-mentioned ester-based urethane rubber, one obtained by a curing reaction of polycaprolactone ester and polyisocyanate can also be used. Although the polycaprolactone ester is not in a bonded state, if the polycaprolactone ester is represented by the general formula [1], it is considered to be as shown below.

General formula [1]: H〇-YuunX+Se-R-→Xtk-OH'.

(In the formula, Xl and X2 are cleavage residues of the caprolactone ring and may be the same or different from each other, m and n are positive real numbers, and R is a connecting group for Xl and X2 and is a divalent organic group. ) The caprolactone compound for forming the caprolactone ring-cleaved residue in the general formula (1) may be a compound having a 3- to 7-membered lactone ring and having 611111 carbon atoms, It also includes those in which a lower alkyl group such as a methyl group or an ethyl group is further bonded to the carbon atoms constituting the lactone ring. Specific examples of such caprolactone compounds include α-caprolactone, β-caprolactone, γ-caprolactone, δ-caprolactone, and ε-caprolactone.
caprolactone, α-methyl-ε-caprolactone, ε
-methyl-ε-caprolactone, β-methyl-ε-caprolactone, and ton.

It has been experimentally confirmed that the camp roll 18 made of ester-based urethane rubber according to the embodiment described above has the following remarkable effects compared to cap rolls made of other rubbers.

For example, as shown in Figure 4, camp rolls made of various materials are bitten into the nozzle (the biting depth is 0.3 m).
m and 0.5 mm), then roll the roll at 60℃ for 2
The depth of the dents remaining on the roll surface when left for a week (corresponding to permanent distortion) was measured. In addition, the cap roll was forcibly rubbed with a blade, and the time required for the roll to wear out (abrasion resistance) was measured. The results of the above tests are summarized in the table below.

According to these results, the cap roll made of ester-based urethane rubber based on the present invention has both creep resistance and abrasion resistance.
It is clear that this is a significant improvement over other rubber products.

Note that in the above embodiment, the cleaning blade 1
As 2, it is possible to use an ester-based urethane comb similar to the one described in 2, which is made of a rubber having relatively high hardness and sufficient hydrophilicity. In this case,
If the surface hydrophilicity of the blade (2) is made larger than the surface hydrophilicity of the cap roll 18, it is expected that the residual ink from the roll 18 can be cleaned more effectively.

Alternatively, for the same purpose, the plate 12 may be made of highly hydrophilic polyhinyl alcohol or the like.

Further, instead of the cleaning blade, a cleaning roll that comes into contact with the roll 18 may be used.

Further, although a roll-shaped cap member is used in the above embodiment, it is of course possible to use a cap portion +A having another shape. The cap member may be substantially entirely composed of the above-mentioned ester-based urethane rubber. In addition, at least the surface layer of the cap member is made of ester-based urethane rubber, and the surface is covered with a flexible film as a protective film, and at least the vicinity area inside the surface (i.e., the protective film is covered with a flexible film). The adjoining inner layer may also be made of ester-based urethane rubber. The present invention is applicable not only to dual inkjet printers but also to supplying liquids such as ink that are easily clogged.

6. Effects of the Invention As described above, the liquid supply device according to the present invention has at least the surface area of the cap member that presses and closes the liquid spout;
Alternatively, since at least the vicinity of the inside of the surface is formed of ester-based urethane rubber, the camp member can be provided with appropriate elasticity, hardness, and surface properties, and the presence of the ester portion in particular improves the hydrophilicity of the cap portion. This makes it possible to effectively remove unnecessary liquid portions from the liquid jetting section.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a perspective view of the main parts of an inkjet printer, Fig. 2 is a right side view of Fig. 1, and Fig. 3 is a print head and cap when not recording. A sectional view showing the positional relationship with the roll, 4th [WI (A) is an enlarged sectional view of the main part in FIG. 3, FIG. 4(B) is a longitudinal sectional view of the cap roll, and FIG. FIG. 3 is a cross-sectional view similar to FIG. 3; In addition, in the symbols shown in the drawings, 1-----Platen 6-------- Nostle (surface) 7-----Print head 10-----Camp roll 11-------Purge nozzle 12-.-Cleaning blade I El---Ester-based urethane rubber elastic layer 19-
---This is an ink ejection opening. Agent: Patent Attorney Hiroshi Aisaka (1 person) No. 10 A You Tatami B No. 2 @ 30 No. 40

Claims (1)

[Claims] (2) having a liquid ejecting part that injects and supplies liquid, and a camp member that presses and closes the ejection port when the liquid ejecting part is not in use; at least the surface of the cap member on the side of the liquid ejecting part; 1. A liquid supply device characterized in that a region or at least a neighboring region inside the surface is made of ester-based urethane rubber.