JPS6362739A - Capping device of ink jet recorder - Google Patents

Abstract

PURPOSE:To improve the solvent resistance, formability, and elasticity of the title capping device by preventing the drying and clogging of an orifice, by a method wherein the gas permeation coefficient of rubber material forming the cap for hermetically sealing the tip of an ink jet head is made not more than a specified valve and the portion of the rubber material forming the surface of the cap is made minutely uneven. CONSTITUTION:An capping rubber 2' equipped to the front of a head 1 is also so constructed as to be able to serve as a part of a head recovery system. That is, the gas bubble in the head together with ink can be extracted through a recovery system tube 5 by operation of a head recovering pump 4. When not operated, the capping rubber 2' becomes a close system by construction so as to isolate the inside of the head recovering pump from the open air and serves as a cap. The material quality of the capping rubber 2' is isobutylene- isoprene rubber and its gas permeation coefficient is made not more than 2.0X10<-15>m<4>/N.S. In order to make this surface finely uneven, which is prominent in releasability, it is treated by B-1 coating with a spray for approximately 5sec.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a capping device for an inkjet recording apparatus for preventing clogging and drying of an inkjet head.

[Conventional technology]

Conventionally, there are many methods for inkjet printers. These can be roughly divided into three types: ∎ Impulse type (on-demand type), ∎ Continuous injection type, and ∎ Electrostatic suction type.

The performance and characteristics of these are very different, but by using ink and fine nozzles,
Common problems include head clogging and drying.

Inkjet printers using these methods generally install a cap on the front side of the orifice of the head when not recording to prevent drying and clogging by blocking the inside of the head from outside air.

[Problems to be Solved by the Invention] Since the cap attached to the front of the head must not have a gap between it and the head, it is preferably soft and elastic, and rubber is generally used.

The rubber used for this cap must have excellent solvent resistance because it comes into contact with the ink. When it comes to rubbers with excellent solvent resistance, there are only a few types of rubbers that can be used, and they are limited to silicone rubber, fluororubber, butyl rubber, and the like.

However, although silicone rubber has excellent solvent resistance, its gas permeability coefficient (nitrogen) is only 20 x 10-"m'/
It is N-3 or higher and has extremely poor gas permeation resistance compared to other rubber materials. Therefore, as shown in FIG. 1, even if the capping rubber 2 is attached to the front surface of the head 1, if the rubber material is silicone rubber, the ink 3 tends to escape as vapor V to the outside. When ink is released to the outside, only the released gas (
Air) G may pass through the capping rubber and enter the inside of the head.

When air enters the inside of the head, it becomes bubbles and the on-demand inkjet recording head is unable to eject ink droplets. Even in continuous injection type or electrostatic suction type heads, if air enters the head, the head may dry out, and as a result, it may become clogged. For this reason, it has been impossible to use silicone rubber, which has a large gas permeability coefficient, as the capping rubber. Further, fluororubber cannot be used because it has poor moldability and relatively high hardness.

In addition, butyl rubber and chlorinated butyl rubber have a unique stickiness, so if they are stored for a long time while attached to the front of the head, they will stick to the head and become impossible to remove. Other rubbers have poor solvent resistance and are out of the question.

In this way, there is no general rubber material that fully satisfies the performance as capping rubber, so conventionally silicone rubber was used, and each time bubbles got into the head, a suction pump was used to remove the bubbles along with the ink. was going on.

[Means for solving problems]

The present invention is an attempt to solve the above-mentioned problems, and includes forming a cap for sealing the tip of an inkjet head from a rubber material, and increasing the gas permeability coefficient of the rubber material to 2. OX 10-"m' / N-S or less, and the rubber material that forms the surface of the cap has a finely uneven shape to prevent drying and clogging of the orifice, and improves solvent resistance, moldability, and elasticity. This is a capping installation with excellent properties.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, a capping rubber 2' attached to the front surface of the head 1 is constructed so that it can also serve as a part of the head recovery system.

That is, by operating the head recovery pump 4, air bubbles inside the head can be removed together with the ink 3 through the recovery system tube 5, and when the head recovery pump 4 is not operated, the inside of the head recovery pump is shut off from outside air. By doing so, the capping rubber 2' becomes a closed system and serves as a cap.

The material of the capping rubber 2' is butyl rubber (manufactured by Daikyo Rubber Co., Ltd.: N11713.B-1 coated product). A B-1 coating (Exxon Chemical Co., Ltd.) is sprayed on the surface for about 5 seconds to create fine irregularities with excellent mold releasability. Since the B-1 coat is a silicone-based resin, it has excellent releasability, and when coated with a spray, the capping rubber surface 6 becomes a fine uneven shape 7 due to the silicone resin, so this and the head front surface 8 Even if it comes into contact with the butyl rubber itself, which has strong adhesiveness, the contact area will be relatively small, so even if it continues to be in contact for a long time, it will not stick to itself. Rubber materials, including butyl rubber, have more or less adhesive properties. Further, the durability of the B-1 coat is very strong, and the coated portion hardly peels off from the butyl rubber surface in general usage. Butyl rubber itself has excellent solvent resistance,
Excellent moldability and elasticity, and gas permeability coefficient (nitrogen) of 0
．． Because it is extremely small at 002x 10-"m'/N-3, it is possible to perform normal ejection without introducing bubbles into the head even if it is left capped in an environment of 50°C/35% RH for a week. The coating is not limited to the B-1 coating, but may be other silicone resins, or resin compositions with excellent mold release properties such as polypropylene resins and aminoalkyd resins.

Furthermore, Table 1 shows the results of examining the characteristics of various rubber materials.

Butyl rubber and chlorinated butyl rubber coated with B-1 have gas permeation resistance, non-stick properties, solvent resistance,
Because it has excellent moldability and elasticity, it can completely satisfy the performance requirements as a capping rubber.

On the other hand, butyl rubber and chlorinated butyl rubber that are not coated with B-1 are highly adhesive and may adhere to the front surface of the head after long-term use.

Also, silicone rubber has a gas permeability coefficient of 2 x 10”m.
'/N-S, which is very large, so bubbles are taken into the head. NBR has problems with solvent resistance, and fluororubber has problems with moldability and flexibility, so the performance as a capping rubber is not satisfactory.

In addition, there are many rubbers other than butyl rubber and chlorinated butyl rubber that are sticky, and by applying B-1 coating to all of these rubbers, stickiness can be suppressed.

〔Effect of the invention〕

As detailed above, according to the present invention, the cap for sealing the tip of the inkjet head is formed of a rubber material, and the gas permeability coefficient of the rubber material is 2. OX
10-"m'/N・S or less, and the rubber material that forms the surface of the cap has a finely uneven shape to prevent drying and clogging of the orifice, and improves solvent resistance, moldability, and
A capping device with excellent elasticity etc. can be provided.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of a capping device, FIG. 2 is a configuration diagram of a capping device showing an embodiment of the present invention, and FIG. 3 is a detailed diagram showing a state of contact between a head and a cap. 1...Head, 2.2'...Capping rubber, 3
... ink, 4 ... pump, 5 ... recovery system tube, 6 ... capping rubber surface, 7 ... unevenness due to B-1 coating, 8 ... head surface.

Claims (3)

[Claims] (1) In a capping device for an inkjet recording device that seals the tip of an inkjet head with a cap, the cap is formed of a rubber material, and
The gas permeability coefficient of the rubber material is 2.0×10^-^1^6m
A capping device for an inkjet recording device, characterized in that the rubber material that forms the surface of the cap has a finely uneven shape. (2) A capping device for an inkjet recording apparatus according to claim 1, wherein the rubber material is butyl rubber. (3) The capping device for an inkjet recording apparatus according to claim 1, wherein the uneven shape is formed by B-1 coating.