JP2863655B2 - Ink holder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink holder used for supplying ink to a print head.

[0002]

2. Description of the Related Art In recent years, there has been remarkable development of OA equipment. Among printers, in particular, from a wire-dot system or a thermal transfer system to an ink-jet system or a laser system.
The beam system is being replaced. Above all, in the ink jet system, the ink container is usually filled with an ink holder in order to uniformly hold the ink.

[0003]

The ink holding member is
Generally, urethane foam is used. However, when the urethane foam is not filled in the container, there is a disadvantage that the supply amount of ink varies depending on the remaining amount of ink, and it is difficult to obtain a stable ink supply. Was. In addition, in the case of a type in which printing is performed while the ink container is movable, the ink in the container always oscillates, and a stable supply of ink cannot be obtained. Sound is also generated.

For this reason, as described above, the ink container is filled with the ink holder. When an ester-based urethane foam is used as the ink holder, the form itself deteriorates depending on the type of ink. However, the decomposed product elutes into the ink, which lowers the surface tension of the ink and causes problems such as blurred printing. Further, in the case of urethane foam, since a foam cell film is formed, when this is filled in an ink container as it is, the ink film has a holding force of ink due to the cell film.
Alternatively, there has been a case where the ink supply capability varies.

[0005]

SUMMARY OF THE INVENTION The present invention provides an ink holder suitable for filling the above-mentioned ink-jet type ink container, in which the ink holding and supply are stabilized, and the ink is deteriorated by the ink. The present invention relates to a urethane foam which is most suitable for an ink holding member which does not cause the occurrence of a wrinkle.

That is, a first gist of the present invention is a urethane foam obtained by reacting a polyether-based polyol with a polyisocyanate in the presence of a catalyst, a foaming agent, a foam stabilizer and other auxiliaries. A styrene and / or acrylonitrile-grafted polymer polyol is used as a component of the polyol, and the polymer polyol is at least 20% (weight ratio) based on all polyol components, and the number of cells of the foam is 20 to 50. / Inch, it is a urethane foam ink holder filled in a container with a compression ratio of 1/2 to 1/10 (volume ratio).

A second gist of the present invention is a urethane foam obtained by reacting a polyether-based polyol and a polyisocyanate in the presence of a catalyst, a foaming agent, a foam stabilizer and other auxiliaries. A polymer polyol having styrene and / or acrylonitrile grafted thereon is used as a component of the polyol, and the polymer polyol accounts for 20% (weight ratio) based on the total polyol component.
When the number of cells of the foam is 50 cells / inch or more, the urethane foam ink holder is filled with a compression ratio of 1/1 to 1/5 (volume ratio) in the volume. is there.

A particularly preferred urethane foam is
This is a three-dimensional network skeleton form from which the form cell film has been removed. The method of removing the form cell film is to immerse the film in an alkaline aqueous solution or to introduce hydrogen gas and oxygen into the form to react them. There is a so-called explosion method, and the latter method is generally used.

Examples of polyols which can be used in the present invention include glycerin, trimethylolpropane, pentaerythritol, sorbitol, sucrose, ethylenediamine,
It is obtained by ring-opening addition polymerization of propylene oxide, ethylene oxide or the like with a polyhydroxyl compound such as diethylenetriamine using an alkali catalyst, and preferably has a hydroxyl value of 100 or less. Specifically, glycerin-based polypropylene glycol (molecular weight: 3000) can be mentioned.

[0010] The graft polyols particularly used in the present invention.
The polymer is obtained by graft-polymerizing one or both of polystyrene and polyacrylonitrile to the above-mentioned polyol, and specifically, V3940 manufactured by Dow Chemical Company.

Examples of usable polyisocyanates include aromatic polyisocyanates and aliphatic polyisocyanates containing two or more isocyanate groups in the same molecule.
Or modified products thereof, specifically, tolylene diisocyanate, diphenylmethane diisocyanate
, Isophorone diisocyanate, xylylene diisocyanate and the like. Hot press compression molding is mentioned as one of the compression methods of the foam. The compression molding conditions are 150 to 210 ° C. and 10 to 100 minutes, and a desired compression ratio is obtained by a spacer or the like. It is.

[0012]

The reason why the structure according to the present invention is effective has not been sufficiently studied, but it has been considered that the polymer-polymer
It is presumed that the use of the solvent can reduce the swelling of the holder due to the solvent contained in the ink, and as a result, the organic components in the holder are less likely to elute.

The present invention relates to the urethane foam ink holder as described above. In particular, since a polyether-based polyol is used as one of the raw materials, both ink components are deteriorated even if they are alkaline or acidic. The worry of becoming unnecessary. By using a specific polymer polyol for a part or all of the polyether-based polyol component, the amount of the polyether-based polyol component eluted into the ink is reduced and the surface tension of the ink is lowered. However, the hardness of the urethane foam is increased, and the drawbacks of deformation and wrinkling during direct compression filling in the container are eliminated.

In the case of a foam having less than 20 cells / inch, even if the foam is compressed to increase the density, since the cell diameter is large, the capillary phenomenon does not work so much.
This is unfavorable because the ink retention is reduced.
In addition, when filling into a container, it is usual to compress and fill the container. However, if the compression ratio is too low, it is difficult to uniformly compress the entire thickness of the foam, and therefore, the capillary phenomenon is less likely to occur. As a result, the ink holding ratio also decreases. On the other hand, if the compression ratio is too high, the ink supply capacity is undesirably reduced. In the present invention, from the above knowledge that the compression ratio of the foam to be filled in the container must be limited by the number of cells of the foam, further points such as ease of filling at the time of compression by the number of cells of the foam In consideration of the above, the compression ratio is optimized according to the number of cells of the form. For this reason, the capillary phenomenon of the foam is effectively exerted and the ink retention rate is excellent, so that a constant ink supply capacity is always provided.

[0015]

The present invention will be described in more detail with reference to the following examples. (Experiment 1) First, the difference between the polyols used for the production of the foam was examined. Experimental Example 1 is a conventional ink holder using a polyester polyol, which was subjected to a film treatment by an explosion method. Experimental Example 2 used a polyether polyol, Experimental Examples 3 and 4 used a styrene-grafted polymer polyol in combination, and Experimental Example 5 used a styrene-grafted polymer polyol. It is. The styrene-grafted polymer polyol actually used was Dow Chemical's V394.
0. Polyether polyol is glycerin-based polypropylene glycol (molecular weight 3000).
It was used. Further, the film treatment of the foam was performed by the same explosion method as in Experimental Example 1. Table 1 shows the properties of the obtained foam.

[0016]

[Table 1]

Test 1: A friction test was performed on the container wall when the ink cartridge was compressed and filled into the ink cartridge container.
In the test, the foam body was compressed to 25%, and the corner of the foam body was deformed (rolled up) when it was pressed into the container.
(Mm). The smaller the deformation, the better the filling in the container. Table 1 shows the results.

Test 2: Degree of elution of organic substances into ink In the test, the foam was immersed in the ink of pH = 10 for 3 weeks, and the weight loss rate (dry) of the foam (ink carrier) was measured. . Of course, the smaller the weight reduction rate, the better the ink holder. Table 1 shows the results.

As a result, no good result was obtained in any of the tests with the conventional ink holder of Experimental Example 1. Also, even when using polyetherpolyol,
In Experimental Example 2 in which no polymer polyol was used and when the amount was very small (Experimental Example 3), the result of Test 1 was not much different from that of the conventional ink holder, Although better results were obtained than the ink carrier of
The results were not satisfactory. On the other hand, Experimental Examples 4 to 5
In Examples 1 and 2 of the present invention, very good results were obtained in each test.

(Experiment 2) Next, with respect to the foam of Experimental Example 4, the number of form cells was adjusted, and a test of the ink holding power when the foam cell was compressed was conducted. The number of the form cells is 10 in the experimental example 6, 30 in the experimental example 7, 40 in the experimental example 8, 60 in the experimental example 9, and 70 in the experimental example 10 (each is a unit / inch). The compression ratio was tested at a compression ratio of 1/1 (original form) to 1/20.

Test 3: Test for ink holding power The test was performed under the following conditions. Height 50mm, bottom area 50mm x 30mm
Is filled with a foam sample, pure water is sufficiently contained in the sample, and 10 cc / min.
The primary pressure of the pump was measured while sucking water at the speed shown in FIG. The pressure immediately before the water in the form disappeared was defined as the ink holding force. Actually, the holding force is -5 to -1.
0 (cm · H ₂ O) is desirable. Above this level, it is difficult for the actual device to generate ink, whereas below this level, ink supply becomes excessive. Table 2 shows the results.

[0022]

[Table 2]

In Experimental Example 6, it can be seen that when the number of form cells is small (the form is coarse), the ink holding ability is not so large. From Experimental Examples 7 and 8, when the number of form cells is about 20 to 50, the compression ratio is preferably about 1/2 to 1/10. From Experimental Examples 9 to 10, when the number of form cells is 50 or more, It is understood that the compression ratio is preferably about 1/1 to 1/5.

[0024]

As described above, the present invention provides a foam using a specific polymer polyol as an ink carrier and having a preferable property as the ink carrier. Because of this, there is no deterioration of the ink,
In addition, stable supply of ink has become possible.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code FI C08L 75:04 (56) References JP-A-2-235646 (JP, A) JP-A-63-207808 (JP, A) JP-A 64-85213 (JP, A) JP-A-3-101971 (JP, A) JP-A-61-296042 (JP, A) JP-A-59-38243 (JP, A) JP-A-63-87242 (JP, A) JP, A) Japanese Utility Model Showa 58-78844 (JP, U) Tokuhyo Hei 4-501392 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 2/175 C08G 18/63 C08J 9/02 CFF C08G 18/63 C08G 101: 00 C08L 75:04

Claims (4)

(57) [Claims] 1. A urethane foam obtained by reacting a polyether-based polyol and a polyisocyanate in the presence of a catalyst, a foaming agent, a foam stabilizer and other auxiliaries, wherein styrene and styrene are used as components of the polyol. And / or a polymer polyol to which acrylonitrile is grafted, wherein the polymer polyol is at least 20% (weight ratio) with respect to the total polyol component and the number of cells of the foam is 20 to 50 cells / inch. Within 1 /
A urethane foam ink holder filled with a compression ratio of 2 to 1/10 (volume ratio). 2. A urethane foam obtained by reacting a polyether-based polyol with a polyisocyanate in the presence of a catalyst, a foaming agent, a foam stabilizer and other auxiliaries, wherein styrene and styrene are used as components of the polyol. And / or using an acrylonitrile-grafted polymer polyol, which polymer polyol is at least 20% (weight ratio) based on the total polyol component, and when the number of foam cells is at least 50 cells / inch, the volume within the volume is 1/1
A urethane foam ink holder filled with a compression ratio of about 1/5 (volume ratio). 3. The urethane foam ink holder according to claim 1, wherein the urethane foam is a three-dimensional network skeleton foam from which a foam cell membrane has been removed. 4. The urethane foam ink holder according to claim 1, wherein the compressed urethane foam is subjected to permanent compression deformation by a hot compression press after production.