JP7175757B2 - Inkjet recording head and manufacturing method thereof - Google Patents

Description

The present invention relates to an ink jet recording head using an epoxy resin molded product and a manufacturing method thereof.

An electromechanical transducer such as a piezo element is used as an energy generating element that generates energy for ejecting ink from ejection openings of a recording head of an inkjet recording apparatus. In addition, there is known a device in which an electromagnetic wave such as a laser is irradiated to generate heat, and ink droplets are ejected by the effect of this heat generation, and a device in which liquid is heated by an electrothermal conversion element having a heating resistor.

Among them, a recording head that uses thermal energy to eject ink droplets (inkjet method) can arrange ejection openings at a high density, so high-resolution printing is possible. Furthermore, among them, a recording head using an electrothermal conversion element as an energy generating element can easily be miniaturized. Furthermore, recording heads using electrothermal conversion elements can fully utilize the advantages of IC technology and microfabrication technology, which have seen remarkable advances in technology and improved reliability in the field of semiconductors in recent years, and facilitate high-density mounting. It is also advantageous because the manufacturing cost is low.

In order to perform recording with even higher definition, a method of manufacturing nozzles for ejecting ink with high precision using a photolithography technique has been used. In recent years, in order to print high-definition images at even higher speeds, there has been a demand for a print head with a longer print width. Specifically, recording heads with a length of 4 inches to 12 inches are also required.
In order to realize a recording head with such a long recording width, Japanese Patent Application Laid-Open No. 2002-200000 discloses that a plurality of recording element substrates having an appropriate number of nozzles and having an appropriate length are arranged on a base plate. A configuration has been proposed that realizes a recording head with a long recording width as a whole. In this case, the base plate member that mounts the ejection pressure generating element and adds the flow path and the like is required to have a high flatness and a small linear expansion coefficient that does not generate stress with the Si substrate. Also, the base plate member is required to have high ink resistance. This is because if impurities or the like dissolve into the ink, they adversely affect the ejection performance, and in the worst case, deposits are generated to clog the nozzles.
Alumina is a representative material having these properties.
However, molding large parts with alumina tends to be very expensive.
Therefore, in order to make the base plate member at a low cost, when the resin molding materials described in Patent Documents 2 and 3, etc., are used instead of alumina, the obtained ink jet recording head has a problem in terms of linear expansion and elution. was not always satisfactory.
Considering chemical resistance, epoxy resin was used as the material, and a liquid composition was used in order to incorporate a large amount of filler. had to increase. However, since the material becomes fine granules or powder, it is impossible to uniformly mix the epoxy resin and the filler. In addition, even if the amount of filler added is reduced and the material is uniformly mixed without becoming powdery, the liquid resin is used. goes down. As a result, the resin and the filler were separated from each other, resulting in a rough surface, making it impossible to ensure surface precision.

JP-A-5-24192 JP 2011-173970 A JP 2009-155370 A JP 2015-206009 A

Patent Document 4 describes the use of a molding material made of liquid resin in order to solve the above problem, but inkjet heads are required to have further long-term reliability and improved productivity for industrial applications. When immersed in ink under extreme conditions such as long-term ink storage or pressure cooker tester (PCT), the thin skin on the filler peels off, the filler is exposed, and the filler is eluted, or in severe cases, it falls off. Sometimes.
SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an ink jet recording head in which a material that achieves both long-term ink resistance and a small coefficient of linear expansion is used for a flow path member.

One aspect of the present invention is
An inkjet recording head having a channel member, wherein the channel member is a thermoset product of a solid epoxy resin composition containing an epoxy resin that is solid at room temperature and a phenolic resin that is solid at room temperature, and an alumina filler. The present invention relates to an ink jet recording head characterized by being formed of
Another aspect of the present invention is a method for manufacturing an inkjet recording head, wherein the flow path member is composed of a solid epoxy resin composition containing an epoxy resin that is solid at room temperature and a phenolic resin that is solid at room temperature; The present invention relates to a method for manufacturing an ink jet recording head characterized by injection molding a thermosetting molding material containing a filler.

According to the present invention, it is possible to provide an ink jet recording head in which a material capable of achieving both long-term ink resistance and a small coefficient of linear expansion is used for a flow path member.

FIG. 1A is a side view and a bottom view showing an example of an inkjet recording head. FIG. 1B is an exploded perspective view showing an example of an inkjet recording head. FIG. 2 is a schematic diagram showing an injection molding machine used in Examples.

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings for an ink jet recording head of the present invention and a method for manufacturing the same.
<Inkjet recording head>
FIG. 1A is a side view and a bottom view showing an example of an inkjet recording head 1000 to which the present invention can be applied. FIG. 1(b) is an exploded perspective view showing the component configuration of the ink jet recording head 1000 of FIG. 1(a).
In the inkjet recording head 1000, nozzle rows are formed in a range that covers the maximum width of the sheet that is assumed to be used. This recording head is an inkjet full-line recording head capable of wide recording without scanning the inkjet recording head.

The inkjet recording head 1000 has a recording element substrate 1100 made of Si, a liquid supply slit 1210, and a base plate 1200 for supporting the recording element substrate. The inkjet recording head 1000 further includes an electric wiring board 1300 for electrically connecting the recording element substrate and the recording apparatus, a liquid reservoir 1510 , and an ink supply member 1500 joined to the base plate 1200 . A plurality of printing element substrates 1100 have ejection openings 1105 and are arranged with high precision in a direction (Y direction) intersecting the printing medium conveying direction (X direction) on a main surface 1200a of the base plate 1200 . In FIG. 1B, the plurality of printing element substrates 1100 are alternately arranged in two rows so that the ends 1109 of the ejection port groups overlap each other. An ink supply member 1500 is arranged on the surface 1200b opposite to the main surface 1200a. The electric wiring board 1300 includes electrode terminals 1320 and openings 1330 .

Since the base plate 1200 forms part of the flow path, it must be highly resistant to liquids such as ink. For example, if even a few ppm of the material of the base plate is eluted into a liquid such as ink, the liquid such as ink evaporates in the vicinity of the ejection port, and deposits adhere to the vicinity of the ejection port. As a result, the ejected liquid droplets may be twisted, resulting in poor printing. The base plate 1200 is bonded to the recording element substrate 1100 made of Si or the like with an adhesive or the like, and high dimensional accuracy is required.
Therefore, in the present invention, the flow path member such as the base plate 1200 is a thermosetting molding material containing a solid epoxy resin composition containing an epoxy resin that is solid at room temperature, a phenolic resin that is solid at room temperature, and an alumina filler. It is formed from hardened material.
The material according to the present invention has a small linear expansion coefficient, excellent moldability, little elution into liquid such as ink, and can be used for injection molding.

In the present invention, by making the resin component solid, a granular molding material can be obtained, and the filler can be highly filled. Especially when an injection molding machine is used, the combination of solid epoxy resin and solid phenolic resin has a relatively low melt viscosity and high wettability to alumina, so the screw in the injection molding machine allows the filler surface to blend well with the resin. can let In particular, when polyfunctional resins are used as the solid epoxy resin and the solid phenol resin, the cross-linking density becomes higher and the filler is adhered more firmly, so that it is difficult to fall off. In addition, by using alumina as the filler, elution from the filler is less likely to occur even if the resin thin film is partially peeled off. Furthermore, by using a solid epoxy resin and a solid phenol resin, the melt viscosity is lowered, and even if the filler content is increased, the fluidity during molding is good.
Hereinafter, the thermosetting molding material for molding the thermosetting material according to the present invention and the components thereof will be described.

The solid epoxy resin composition includes an epoxy resin that is solid at normal temperature (hereinafter also referred to as solid epoxy resin), a phenol resin that is solid at normal temperature as a curing agent (hereinafter also referred to as phenol curing agent), a curing accelerator, and a silane agent. etc. The base solid epoxy resin and phenolic hardener should be solid, but the other additives may be liquid or solid. Epoxy resins, which are generally added for the purpose of modification as necessary, may be either liquid or solid. The solid epoxy resin composition may be solid at room temperature, and preferably has a melting point of 50° C. or higher in consideration of storage stability and handling.

The solid epoxy resin is preferably solid at room temperature (15 to 35°C) and has a melting point in the range of 50 to 120°C. Solid epoxy resins include naphthalene skeleton type, cresol novolak type, triphenyl type, biphenyl type, dicyclopentadiene type, naphthol skeleton type, bisphenol novolac type, glycidylamine type, phenolbiphenylene type, and alicyclic epoxy. be done. One of these epoxy resins may be used, or two or more thereof may be used in combination.
Among solid epoxy resins, polyfunctional epoxy resins can be preferably used from the viewpoint of ink resistance, adhesion to filler, and molding tact. Among them, triphenyl-type epoxy resin has a high glass transition point when combined with a phenolic curing agent, and can form a molded product with excellent ink resistance, so it can be used optimally as a flow channel member. can.

The solid phenolic resin used as the curing agent is preferably solid at room temperature (15 to 35°C) and has a melting point in the range of 50 to 120°C. Examples of solid phenolic resins include phenolic novolak type, xylylene novolak type, bis A novolak type, triphenylmethane novolak type, biphenyl novolac type, dicyclopentadiene type phenolic resins, and the like. These phenol resins may be used alone or in combination of two or more.
Among solid phenolic resins, polyfunctional epoxy resins can be preferably used from the viewpoint of ink resistance, adhesion to filler, and molding tact. In the present invention, by using a phenolic resin as a curing agent, the wettability of the solid epoxy resin composition with respect to the alumina filler is improved, and the epoxy resin composition and the alumina filler are strongly adhered to each other, resulting in reliability in long-term ink storage. is obtained.

In the thermosetting molding material according to the present invention, if phenolic hydroxyl groups remain in the molded article after the thermosetting reaction, the ink resistance is lowered, so it is necessary to increase the amount of epoxy. Therefore, the content of the solid epoxy resin and the solid phenolic resin is such that the molar ratio of the epoxy group of the solid epoxy resin to the phenolic hydroxyl group of the solid phenolic resin is in the range of 1.0:0.7 to 1.0:0.98. and more preferably in the range of 1.0:0.90 to 1.0:0.98.
The total content of solid epoxy resin and solid phenol resin in the thermosetting molding material is preferably 8-30% by mass, more preferably 9-15% by mass.

Solid phenolic resins, which are curing agents, generally have low reactivity and are preferably used in combination with curing accelerators. Moreover, by adding a curing accelerator, the reaction of epoxy groups that have not reacted with phenolic hydroxyl groups can also proceed. Therefore, the molded article does not contain unreacted components, and has good ink resistance. Such curing accelerators include imidazoles such as 2-ethyl-4-methylimidazole, 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole imidazoles, tertiary amines, and triphenylphosphines. etc.
Also, the content of the curing accelerator in the thermosetting molding material is preferably 0.01 to 0.5% by mass, more preferably 0.1 to 0.3% by mass.

In the present invention, an alumina filler is used because it suppresses elution into the ink and has a small coefficient of linear expansion. The alumina filler is preferably spherical in order to suppress linear expansion and achieve high packing, and it is preferred to combine alumina fillers having different particle sizes in order to achieve the closest packing. For close packing, the particle size of the alumina filler with the larger average particle size is preferably 3 to 5 times the particle size of the alumina filler with the smaller average particle size. The particle size of the alumina filler having the larger average particle size is preferably 15 to 50 μm, and the particle size of the alumina filler having the smaller average particle size is preferably 3 to 15 μm. The weight ratio of the alumina filler having a large average particle size and the alumina filler having a small average particle size is preferably large:small=9:1 to 6:4. The average particle size of the whole is preferably 50 μm or less, and if it is larger than this, the fillability of details may be deteriorated, and the flowability during molding may be deteriorated. On the other hand, when the particle size is less than 5 μm, the specific surface area increases and the curing properties become better, but the fluidity during molding decreases. Therefore, the average particle diameter of the alumina filler as a whole is particularly preferably 10 to 30 μm. In addition, the average particle diameter here means a number average particle diameter.
The filling amount of the alumina filler in the thermosetting product should be as large as possible in consideration of ink resistance, coefficient of linear expansion, and thermal conductivity. more preferred.

The alumina filler is preferably treated with a silane coupling agent in order to improve adhesion to the resin component. In this case, the amount of the silane coupling agent used is preferably 0.01 to 0.06 parts by mass, more preferably 0.02 to 0.04 parts by mass, with respect to 100 parts by mass of the alumina filler. Silane coupling agents include γ-glycidoxypropyltrimethoxysilane, β-(3,4 epoxycyclohexyl)-ethyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and the like. be done. A titanate-based or aluminate-based coupling agent may also be used. One of these silane coupling agents may be used, or two or more thereof may be used in combination.

Next, the molding material according to the present invention will be described with reference to examples and comparative examples. Unless otherwise specified, "parts" are units of mass.

<Manufacture of molding material>
Molding materials 1 to 11 listed in Tables 1 and 2 were prepared. Specifically, the solid epoxy resin shown in Tables 1 and 2, the solid phenolic resin as a curing agent, the curing accelerator (curing catalyst), and the flow improver were mixed in the amounts shown in Tables 1 and 2. After that, the mixture was stirred while adding the filler little by little. The materials were mixed by a mixer, hot-melted and mixed by hot rolls and a kneader, cooled and solidified, pulverized, and filtered so as to have a uniform particle size to obtain a molding material. The molding material was evaluated as follows. The results are also shown in Tables 1 and 2.
The treatment of the alumina filler used as the filler with the silane coupling agent was carried out as follows.
10 kg of alumina filler is put into a Henschel mixer, and while stirring at 700 rpm, a solution consisting of 3 g of a silane coupling agent (product name: A-187, manufactured by Momentive Performance Materials) and 400 g of ethanol is added. Add and stir for 5 minutes. After confirming that the whole is a uniform viscous solution, steam is added. Then, when the solvent was evaporated by steam, the rotation speed of stirring was set to 1400 rpm, and after holding at 100° C. for 5 minutes, the alumina filler was treated with the silane coupling agent by cooling.

<Injection moldability evaluation>
Each of the obtained molding materials was injection molded using the injection molding machine shown in FIG. 2, and the injection moldability during the injection molding was evaluated.
A molding material is charged from the hopper 21 . The charged material is extruded toward the mold 27 by the screw 22 . Heated by a heater 23 while being pressed, the material changes from a solid 24 to a sticky state 25 to a liquid state 26 and is extruded into a hot mold 27 where it cures into a molded article 28 .
In the injection molding process described above, the injection moldability was evaluated by observing whether or not each molding material could be injection molded as usual. The results are shown in Table 1 or Table 2. The properties after kneading in the table were confirmed by visual inspection and finger touch.
The setting conditions of the injection molding machine are as follows. Using an injection molding machine (product name: EC75SXR, manufactured by Toshiba Machine Co., Ltd.), a flat plate of 40 mm×40 mm×3 mm was molded at 175° C. for 2 minutes.

<Ink resistance evaluation>
The molded article molded by the injection moldability evaluation was subjected to additional heat curing at 180° C. for 8 hours, and the ink resistance test was performed as follows. Resin compositions 9 to 11 of Comparative Examples could not be injection-molded, so compression molding was performed and the obtained molded articles were evaluated. Ink resistance can also be evaluated on molded products immediately after molding, but phenol curing agents have relatively low curing reactivity, and it is assumed that the reaction of the constituent components of the molded product is not complete. Therefore, additional heating was performed in consideration of long-term ink resistance.

The resulting molded product was immersed in a transparent ink for distribution (distribution ink for inkjet printers) (trade name: F850, manufactured by Canon) and heated at 121° C. for 10 hours using PCT. After air-cooling to room temperature, the presence or absence of elution of filler (inorganic matter) from the molded article into the ink was confirmed by an ICP emission spectrometer, and the presence or absence of dropout of the filler from the molded article was observed. Molded articles for which no elution or detachment was observed were again heated at 121° C. for 250 hours in the PCT, and the presence or absence of elution of filler and the presence or absence of detachment of filler were observed in the same manner. Results are shown in Tables 1 and 2.

The molding materials 1 to 7 of Examples and the molding material 8 of Comparative Example could be molded by injection molding as usual.
On the other hand, the molding materials 9 to 11 of Comparative Examples were in a sticky state, and when the materials were put into the injection molding machine, the hopper 21 was clogged with the materials, and molding could not be performed under normal conditions.

Since the molding materials 1 to 7 of Examples use a polyfunctional material and a solid material, they show good ink resistance without filler elution or falling off at 121° C. for up to 10 hours. In the molding materials 3 and 4 of Examples, a polyfunctional epoxy resin having a triphenyl skeleton is used as the epoxy resin, and the Tg is 185° C., which is 20 to 40° C. higher than the other molding materials. Since the curing temperature of the mounting material used during manufacturing is 180° C. at the highest, the molding materials 3 and 4 of Examples are not subjected to stress due to the difference in linear expansion during manufacturing and have a high crosslink density. , ink resistance is good. Furthermore, the molding materials 3 and 4 of Examples showed less filler drop-out compared to other resin compositions when observing the results of 250 hours at 121°C. In particular, in molding material 4, since the alumina filler was subjected to silane coupling treatment to improve adhesion to the resin component, no filler drop-off was observed, and the ink resistance was particularly excellent.

In this example, the alumina filler is contained as much as 90% by mass, and the thermal conductivity is also about 5 W/mK. Since the recording element substrate generates heat during printing, it is necessary to let the heat escape. In particular, in the case of an industrial ink jet head, since a large number of recording element substrates are arranged, the resin composition of this embodiment is effective in this respect. characteristics.
In the molding material 8 of the comparative example, since the alumina filler was not contained and the filler was filled with a large amount of fused quartz, a small amount of silica protruding from the surface was eluted. If the amount of elution is large, it may re-precipitate or react with the ink components to form a solid matter, which may cause uneven ejection or non-ejection.
Further, in the molding materials 9 to 11 of the comparative examples, the filler fell off because they were not sufficiently adhered to the alumina. The fallen filler is carried together with the ink and stays in the ink flow path to increase the flow resistance, and in the worst case, clog the ejection port, causing non-ejection.

1000 Inkjet recording head 1100 Recording element substrate 1105 Ejection port 1109 End of ejection port group 1200 Base plate 1210 Ink supply slit 1300 Electric wiring board 1320 Electrode terminal 1330 Opening 1500 Ink supply member 1510 Ink reservoir 21 Hopper 22 Screw 23 Heater 24 Materials A.
25 Material B
26 Material C
27 mold 28 molded product

Claims (10)

An inkjet recording head having a channel member, wherein the channel member is a thermoset product of a solid epoxy resin composition containing an epoxy resin that is solid at room temperature and a phenolic resin that is solid at room temperature, and an alumina filler. An inkjet recording head characterized by being formed of 2. An ink jet recording head according to claim 1, wherein said epoxy resin and said phenolic resin are polyfunctional. 3. An ink jet recording head according to claim 1, wherein said epoxy resin and said phenol resin each have a melting point of 50[deg.] C. or higher. 4. The ink jet recording head according to claim 1, wherein said alumina filler is treated with a silane coupling agent. 5. The ink jet recording head according to claim 1, wherein the flow path member is a base plate for supporting the recording element substrate. The ink jet recording head according to any one of claims 1 to 5, wherein the epoxy resin is a triphenyl type epoxy resin. 7. The method according to any one of claims 1 to 6, wherein the molar ratio of the epoxy group of the epoxy resin and the phenolic hydroxyl group of the phenolic resin is in the range of 1.0:0.7 to 1.0:0.98. The ink jet recording head described. The inkjet recording head according to any one of claims 1 to 7, wherein the content of said alumina filler is 70 to 92% by mass. The ink jet recording head according to any one of claims 1 to 7, wherein the content of said alumina filler is 85 to 91% by mass. 10. The method for manufacturing an ink jet recording head according to claim 1, wherein the flow channel member is a solid epoxy resin composition containing an epoxy resin that is solid at room temperature and a phenolic resin that is solid at room temperature. A method for manufacturing an ink jet recording head, characterized by forming by injection molding a thermosetting molding material containing an alumina filler and an alumina filler.

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