JP6878902B2 - Nozzle plate, liquid discharge head, liquid discharge unit, liquid discharge device, manufacturing method of nozzle plate - Google Patents

Description

The present invention relates to a nozzle plate, a liquid discharge head, a liquid discharge unit, a device for discharging liquid, and a method for manufacturing a nozzle plate.

The liquid discharge head (droplet discharge head) for discharging the liquid is provided with a liquid repellent film on the surface on the liquid discharge surface side for discharging the liquid.

Conventionally, a fluororesin having an ether bond in a heterocyclic structure such as Teflon (registered trademark) AF is used as the liquid repellent film, and a dipping method, a transfer method, a spray coating method, etc. It is known that the spin coating method, the wire bar coating method, the thermal vapor deposition method, the meniscus coating method and the like are used, and that the film is heated at a temperature equal to or higher than the glass transition point after film formation.

Japanese Unexamined Patent Publication No. 4-21959 Japanese Unexamined Patent Publication No. 2008-188911 Japanese Unexamined Patent Publication No. 2010-5994 Japanese Unexamined Patent Publication No. 2010-260281 Japanese Unexamined Patent Publication No. 7-68765

By the way, the nozzle plate is wiped (wiping) by a wiping member (wiping member) in order to maintain and recover the liquid ejection performance, but if the liquid repellent film is peeled off or damaged by wiping, injection bending may occur.

Therefore, it is required to suppress jet bending by enhancing the adhesion of the liquid-repellent film and enhancing the wiping resistance while exhibiting sufficient liquid-repellent property. Therefore, the present inventors have diligently studied the liquid repellency and adhesion when a film containing a fluororesin having a fluorine-containing heterocyclic structure having an ether bond as a PTFE skeleton is used as a liquid repellent film, and liquid repellent. It was found that the Martens hardness and elastic work rate of the film affect the liquid repellency and adhesion.

The present invention has been made in view of the above problems, and an object of the present invention is to suppress injection bending.

In order to solve the above problems, the nozzle plate according to the present invention is
A nozzle plate having a nozzle for discharging a liquid and having a liquid-repellent film at least on the surface on the liquid discharge surface side.
The liquid-repellent film is a film containing a fluororesin having a fluorine-containing heterocyclic structure having an ether bond in a PTFE skeleton, and has a Martens hardness of 100 N / mm2 or more and an elastic power of 20% or more on the surface of the film. Fluorine
There is a relationship of c <d between the number average molecular weight c of the fluororesin at the interface with the substrate in the liquid-repellent film and the number average molecular weight d of the fluororesin on the outermost surface of the film. And said.

According to the present invention, injection bending can be suppressed.

It is a plane explanatory view of the nozzle plate which concerns on 1st Embodiment of this invention. Similarly, it is an enlarged cross-sectional explanatory view of one nozzle part. It is a plane explanatory view of the nozzle hole part which provides the explanation of the film thickness of a liquid repellent film. It is an enlarged cross-sectional explanatory view of one nozzle part of the nozzle plate which concerns on 2nd Embodiment of this invention. It is explanatory drawing which provides the explanation of an example of the manufacturing method of a nozzle plate. It is also an explanatory diagram provided for the explanation of vacuum vapor deposition. It is also an SEM photograph of a liquid-repellent film provided for explanation in the state before baking. It is also an SEM photograph of a liquid-repellent film provided for explanation in the state after baking. It is explanatory drawing explaining an example of the change of Martens hardness and elastic power with respect to annealing time. It is explanatory drawing of a Vickers indenter. It is explanatory drawing which provides the explanation of the measurement of the minute hardness. It is explanatory drawing of an example of the measurement profile of a microhardness. It is explanatory drawing which provides for the explanation of the change of the thin-film deposition film by baking. It is explanatory drawing which shows an example of the relationship between the bake temperature, the Martens hardness and the peeling load. It is explanatory drawing which shows an example of the relationship between baking temperature, elastic power and peeling load. It is explanatory drawing which shows the other example of the relationship of baking temperature, Martens hardness and peeling load. It is explanatory drawing which shows an example of the relationship between baking temperature, elastic power and peeling load. It is explanatory drawing which provides the explanation of the wiping resistance evaluation apparatus. It is sectional drawing in the direction orthogonal to the nozzle arrangement direction (the liquid chamber longitudinal direction) of the example of the liquid discharge head which concerns on this invention. It is sectional drawing in the nozzle arrangement direction (the liquid chamber short side direction) of the head. It is a plane explanatory view of the main part of an example of the apparatus which discharges a liquid which concerns on this invention. It is explanatory drawing of the main part of the apparatus. It is a plane explanatory view of the main part of another example of the liquid discharge unit which concerns on this invention. It is a front explanatory view of still another example of the liquid discharge unit which concerns on this invention. It is explanatory drawing explaining an example of the change of the ratio of the heterocyclic structure having an ether bond with respect to the heterocyclic skeleton having an ether bond, and the change of the glass transition point Tg.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a plan explanatory view of a nozzle plate according to the same embodiment, and FIG. 2 is an enlarged cross-sectional explanatory view of one nozzle portion.

The nozzle plate 1 includes a nozzle base material 20 in which a hole (hereinafter, referred to as “nozzle hole”) 21 serving as a nozzle 11 for discharging a liquid is formed, an intermediate layer 30 formed on the surface of the nozzle base material 20 and the like. It has a liquid repellent film 40 formed on the surface on the liquid discharge surface side.

The nozzle base material 20 is, for example, a metal flat plate member. A stainless steel metal flat plate member is used as the nozzle base material 20, but the nozzle base material 20 is not limited to this.

The intermediate layer 30 is composed of one or a plurality of layers such as a _{SiO 2 layer and a silane coupling agent layer, which are base layers.}

The liquid-repellent film 40 is a film containing a fluororesin (hereinafter, also simply referred to as “fluororesin”) having a fluororesin-containing heterocyclic structure having an ether bond in a PTFE skeleton. The fluororesin preferably has a glass transition point Tg of room temperature or higher.

The PTFE (polytetrafluoroethylene) skeleton is a main chain that repeats the structural unit of TFE (tetrafluoroethylene) represented by the following structural formula (1).

The liquid-repellent film 40 has a slope region 41 in which a slope 41a is formed on the outer peripheral portion of the nozzle 11 so as to be inclined in a direction in which the film thickness becomes thinner toward the edge 11a side of the nozzle 11. The slope 41a of the slope region 41 may be slanted in a straight line in cross-sectional shape, or may be slanted in a curved shape.

The film thickness of the region 42 other than the slope region 41 other than the slope region 41 of the liquid repellent film 40 is substantially constant and flat.

As described above, the liquid repellent film 40 has a slope region 41 that is inclined in the outer peripheral portion of the nozzle 11 in a direction in which the film thickness becomes thinner toward the edge side of the nozzle 11, so that the nozzle of the liquid repellent film 40 Since the edge on the 11 side comes to a position lower than the surrounding water-repellent film 40, the wiper member is less likely to interfere with the edge of the water-repellent film 40, so that the wiper member is caught on the edge of the liquid-repellent film 40. Can be reduced / prevented.

Thereby, the durability of the liquid repellent film 40 can be improved.

Here, the film thickness of the liquid repellent film 40 will be described with reference to FIG. FIG. 3 is a plan explanatory view of a nozzle hole portion provided for the same description.

As shown in FIG. 3, the film thickness was measured at 20 points on the circumferential CC 5 μm away from the nozzle center 11o on the normal line of the edge 11a from the edge 11a of the nozzle 11, and the following equation (2) was obtained. Let the arithmetic mean of the population of film thicknesses obtained in 1 be the average film thickness m.

Then, the quantity obtained by the following equation (3) is defined as the variance, and the positive square root σ of this variance is defined as the standard deviation of the population (thickness).

Here, the smaller the coefficient of variation "film thickness standard deviation σ / average film thickness m", the smaller the variation in film thickness with respect to the film thickness and the flatter it is.

The average film thickness a on the circumferential CC was measured by an ellipsometer with a spot diameter of φ10 μm at equal intervals on the circumferential CC.

When the presence or absence of liquid wiping residue on the surface after wiping was evaluated when this σ / m was changed, σ / m = 0.03: none, σ / m = 0.06: none, σ / m = 0. 09: No, but σ / m = 0.12: Yes, σ / m = 0.15: Yes. When there is no unwiped liquid, the ejected liquid does not bend.

Therefore, by setting σ / m <0.1, the injection bending can be reduced.

Further, the fluorine compound having a heterocyclic structure at the interface with the substrate in the liquid repellent film 40 has the same number average molecular weight c as the number average molecular weight c of the fluororesin having a fluorine-containing heterocyclic structure having an ether bond in the PTFE skeleton and the same on the outermost surface of the film. It is preferable that there is a relationship of c <d with the number average molecular weight d of the fluororesin.

That is, when the molecular weight is relatively low, the molecular motility becomes active in a high temperature environment, so that the bonding state with the substrate becomes good. On the other hand, when the molecular weight is high, the durability against physical wear is improved on the outermost surface of the film which comes into direct contact with the wiping member.

The magnitude of the molecular weight of the liquid-repellent film in the depth direction is achievable by controlling the temperature at the time of resin vapor deposition because it evaporates preferentially from the one having a low molecular weight by gradually increasing the temperature.

The average molecular weight of the resin in the liquid repellent film 40 was measured by GPC. The measurement results were c = 240,000 and d = 290,000.

Further, the intermediate layer 30 is preferably a silane coupling agent layer in which the underlying layer of the liquid repellent film 40 has an amino group.

As a result, high adhesion can be obtained by the interaction between the amino group and the liquid repellent material.

Further, the film thickness of the liquid repellent film 40 is preferably in the range of 1 μm or more and 3 μm or less.

Next, the second embodiment of the present invention will be described with reference to FIG. FIG. 4 is an enlarged cross-sectional explanatory view of one nozzle portion of the nozzle plate according to the same embodiment.

In the present embodiment, the nozzle plate 1 also forms an intermediate layer 30 on the inner wall surface of the nozzle hole 21 of the nozzle base material 20, and forms a liquid repellent film 40 on the inner wall surface of the nozzle 11.

Here, the film thickness t2 of the liquid-repellent film 40b on the inner wall surface of the nozzle 11 (corresponding to the wall surface of the nozzle hole 21 of the nozzle base material 20) is 1/10 of the film thickness t1 of the region 42 of the liquid-repellent film 40a. The following (t2 / t1 <0.1) is preferable.

The film thickness t2 of the liquid-repellent film 40a on the inner wall surface of the nozzle 11 increases in variation in nozzle diameter as the film thickness increases. Therefore, it is preferable that the film thickness t2 is thin in order to realize stable discharge. On the other hand, the thicker the film thickness t1 of the liquid repellent film 40a on the liquid discharge surface side, the better the durability.

The liquid-repellent film 40 having these contradictory film thicknesses can be obtained, for example, by forming a film using a vapor phase method.

The film thickness can be measured by exposing the nozzle cross section by ion polishing and observing by SEM.

The relationship between the film thickness t2 of the liquid-repellent film 40b on the inner wall surface of the nozzle 11 and the film thickness t1 of the region 42 of the liquid-repellent film 40a was evaluated. If the ratio of t2 / t1 exceeds 0.1, a water-repellent film is formed by the dip method, and then the dip liquid that has flowed into the nozzle is blown into the nozzle to open the nozzle. Samples were obtained by drying.

As a result, the presence or absence of injection bending was t2 / t1 <0.05: none, t2 / t1 <0.10: none, and t2 / t1 ≧ 0.3: yes. From this, if t2 / t1 <0.10, the injection bending can be reduced or prevented.

Next, the liquid repellent film in each of the above embodiments will be described.

The fluorine-containing heterocyclic structure having an ether bond is a structure of a 5- to 8-membered ring organic compound containing 1 to 2 oxygens as heteroatoms in the chemical structural formula.

From the viewpoint of liquid repellency (contact angle), it is preferable to use a fluororesin having a fluorine content of 50% by mass or more. The ratio of the ring structure in the main chain is preferably 20% by mass or more, more preferably 30% by mass, from the viewpoints of the strength of the target coating film, solubility in a solvent, adhesion to the nozzle substrate, and the like. % Or more is preferable.

Of the fluororesins, it is particularly preferable to use an amorphous fluororesin. Since the amorphous fluororesin is excellent in film strength, adhesion to a substrate, film uniformity, etc., the effect of the present invention can be further exhibited.

Examples of the structural unit having a fluorine-containing heterocyclic structure having an ether bond include those represented by the following structural formulas (2) to (6).

A fluororesin having a fluorine-containing heterocyclic structure having an ether bond of the structural unit represented by the structural unit (5) in the PTFE skeleton is produced by DuPont under the trade name of Teflon (registered trademark) AF. Teflon (registered trademark) AF is a copolymer [TFE / PDD: tetrafluoroethylene-perfluorodioxol copolymer] having a tetrafluoroethylene structure and a dioxol structure having a perfluoroalkyl group, and is liquid-repellent against various liquids. It is excellent and preferable in terms of sex.

The tetrafluoroethylene-perfluorodioxol copolymer is an amorphous fluororesin and is a transparent resin. As the tetrafluoroethylene-perfluorodioxol copolymer, an appropriately synthesized copolymer may be used, or a commercially available product may be used.

The tetrafluoroethylene-perfluorodioxol copolymer has a glass transition point as shown in FIG. 5 as the ratio of the perfluoroidioxol copolymer (PDD) component to the tetrafluoroethylene (TFE) component increases. Rise. Commercially available products are Teflon (registered trademark) AF1600 having a glass transition point of 160 ° C. and Teflon (registered trademark) AF2400 having a glass transition point of 240 ° C.

FIG. 25 is a diagram showing the relationship between the ratio of TFE and PDD in tetrafluoroethylene perfluorodioxol (TFE / PDD) and the glass transition temperature.

Further, a fluororesin having a fluorine-containing heterocyclic structure having an ether bond of the structural unit represented by the structural unit (2) in the PTFE skeleton is available from Solvay under the trade name of Hyflon.

Further, the fluororesin having a fluorine-containing heterocyclic structure having an ether bond of the structural unit represented by the above structural formula (6) in the PTFE skeleton is a Asahi Glass stock under the trade name of Cytop CTX-105 or Cytop CTX-805. It is issued by the company.

As described above, the average thickness of the liquid repellent film 40 (fluororesin layer) is preferably 1 μm to 3 μm.

In order to obtain a smooth surface without the unevenness provided on the nozzle base material 20 affecting the surface of the fluororesin layer forming the liquid repellent film 40, a film thickness of 1 μm or more is required, and the shape of the nozzle 11 From the viewpoint of maintaining the nozzle diameter and the nozzle diameter, a thinner one is preferable. When the average thickness of the liquid repellent film 40 is in the range of 1 μm to 3 μm, it is preferable from the viewpoint of wiping durability and the shape of the nozzle 11. The average thickness can be measured, for example, by cross-sectional SEM.

The arithmetic mean roughness Ra of the liquid repellent film 4 (fluororesin layer) is preferably 1.0 nm or less. When the average roughness Ra is 1.0 nm or less, the nozzle surface becomes extremely smooth, the amount of unwiped residue due to wiping is reduced, and the wear resistance is also excellent.

The arithmetic mean roughness Ra is defined as follows. In the section of length l, only the reference length is extracted from the roughness curve in the direction of the average line, the X axis is taken in the direction of the average line of the extracted portion, and the Y axis is taken in the direction of the longitudinal magnification. When the roughness curve is expressed by y = f (x), the value obtained by the following equation (1) is expressed in micrometers (μm).

The arithmetic mean roughness Ra was measured by the force tapping mode (in air) of an atomic force microscope (Dimension Icon manufactured by Bruker AEX Co., Ltd.). A low spring constant silicon cantilever (OMCL-AC240TS-C3 manufactured by Olympus Corporation) was used as the cantilever, and the measurement length was 10 μm.

Next, an example of the method for manufacturing the nozzle plate according to the present invention will be described with reference to FIG. FIG. 5 is an explanatory diagram for the same explanation.

In the base material preparation step of FIG. 5A, a mirror polishing step and a pre-cleaning step are performed on the metal flat plate member to be the nozzle base material 20.

The nozzle base material 20 is, for example, a metal flat plate member having a length of 30 mm, a width of 15 mm, and a thickness of 0.05 mm in which a nozzle hole 21 is opened by press working.

As the metal flat plate member, stainless steel as a typical example of an iron-based alloy can be used. As described in JIS G0203: 2000 No. 4201, the “stainless steel” is a steel having a Cr content of 10.5% or more, and various steel types can be used.

As the steel type, if it is an austenitic stainless steel, Cr: 10.5 to 35% by mass, preferably 11 to 30% by mass, Ni: about 5 to 30% by mass, and if it is a ferritic stainless steel, Cr: 10.5 to 35%. A steel grade of about mass%, preferably about 15 to 30% by mass can be adopted. For example, the steel grades specified in JIS G4305: 2005 and JIS G4312-1991 can be exemplified. Alternatively, stainless steel can be used in which other alloying elements are added based on these standard steel grades to improve various characteristics.

As the nickel-based alloy, a highly corrosion-resistant Ni—Cr—Fe alloy containing Cr: 12 to 27% by mass and Fe: 5 to 18% by mass can be used. This type of alloy is known as "Inconel alloy".

Then, a metal flat plate member is punched from the side opposite to the discharge surface, and burrs generated by the punching are removed by polishing or chemical etching.

Next, in the intermediate layer forming step of FIG. 5B, as the intermediate layer 30, an SIO ₂ film 31 is formed on the surface of the nozzle base material 20 by a sputtering method or the like, and tape is applied to the surface opposite to the liquid discharge surface side. After attaching 60, a silane coupling agent layer 32 is formed on the surface of the _{SIO 2 film 31.}

Here, as the silane coupling agent, a coupling agent having an amino group is preferable, and 3-aminopropyltriethoxysilane is particularly preferable. Specific examples thereof include KBE-903 (Shin-Etsu Chemical) and A1100 (Momentive Performance Materials). Any method such as a dipping method, a spin coating method, or a spray method may be used to form the silane coupling agent layer 32.

Since the coupling agent having an amino group has a good affinity between the ether portion of the heterocycle in the molecule of the fluororesin and the amino group, fluorine is provided by further providing a silane coupling agent having an amino group on the silica layer. The fixability of the resin is greatly improved.

After that, the film formation step of the liquid repellent film 40 shown in FIG. 5C is performed, and the liquid repellent material is vapor-deposited on the nozzle base material 20 by a vapor deposition method to form a film. At this time, the liquid-repellent film 40 is formed on the surface of the silane coupling agent layer 32 (the surface of the intermediate layer 30) on the nozzle base material 20.

The fluororesin having a fluorine-containing heterocyclic structure having an ether bond in the PTFE skeleton is heated to 350 to 420 ° C. under a high vacuum of ^{1.5 to 8.0 × 10 -3 Pa, and the thickness of the vapor deposition film is increased.} Vacuum vapor deposition is performed until the thickness on the nozzle substrate 20 facing the vapor deposition source is about 1 to 3 μm. For example, as shown in FIG. 6, vacuum vapor deposition is performed by arranging the vapor deposition source 501 and the nozzle base material 20 so as to face each other in the vacuum chamber 500.

Then, as shown in FIG. 5D, a flattening step by annealing (heat treatment) is performed.

The nozzle base material 20 is not particularly heated, and the film obtained by vapor deposition at a natural temperature is baked (annealed) at a temperature equal to or higher than the glass transition point Tg of the fluororesin.

The baking may be performed by any method such as a convection drying oven, a circulating ventilation type drying oven, a flash annealing device, a halogen lamp heater, and a vacuum dryer, but it is preferably carried out in a nitrogen atmosphere. The bake temperature is preferably 20 to 30 degrees higher than the glass transition point Tg. For example, when the glass transition point Tg is 160 degrees (Teflon (registered trademark) AF1600), heating at about 180 ° C. is preferable.

Fluororesin as a liquid-repellent film 40 having a slope region 41 that is dense, has a smooth surface, and becomes thinner as it approaches the nozzle 11 by baking (annealing) at a temperature equal to or higher than the glass transition point Tg of the fluororesin. It becomes a film.

For example, before baking, as shown in FIG. 7, pores 600 exist inside the film, and the film surface has a contact angle with pure water of 114 ° and Ra = 8 nm, whereas after baking, after baking, As shown in FIG. 8, there are no cavities inside the membrane, and the surface of the membrane has a contact angle with pure water of 129 ° and Ra of 1 nm or less.

Further, the surface of the fluororesin film had a tapered shape (slope shape) within a range of 40 nm from the edge 11a of the nozzle 11, and a flat surface outside the periphery of 40 nm.

The heat treatment (annealing) may be performed during the vapor deposition step instead of the heat treatment after the vapor deposition step (FIG. 5 (c)). By depositing the fluororesin while heating the nozzle base material 20, the surface of the fluororesin can be smoothed even by heat treatment at a temperature that does not reach the glass transition point Tg of the fluororesin.

Next, a method for forming a liquid-repellent film will be described.

The liquid-repellent film formed on the nozzle substrate by vapor deposition using a fluororesin having a fluorine-containing heterocyclic structure having an ether bond in the PTFE skeleton is different from the liquid-repellent film obtained by the liquid phase method (for example, dipping). It was found that the outermost surface became a minute uneven state. Further, as described above, there are pores inside the membrane.

Therefore, in the case of a liquid having a low surface tension, such as a liquid to which a surfactant is added or a liquid composed of an organic solvent, the original liquid repellency of the fluororesin provided on the nozzle surface cannot be ensured.

Therefore, in the above embodiment, the liquid-repellent film is made to flow by heating the liquid-repellent film after or during the vapor deposition, so that the surface of the film is smoothed and the pores inside the film are eliminated. There is.

Therefore, when the liquid-repellent film is heated after vapor deposition, the heat treatment is performed at a temperature equal to or higher than the glass transition point Tg of the fluororesin. On the other hand, heating at a temperature significantly higher than the glass transition point Tg melts and breaks the film shape with high dimensional accuracy obtained by the vapor phase method, so that the temperature is 20 to 30 degrees higher than the glass transition point Tg. It is preferable to heat-treat the liquid-repellent film after the film formation.

When heat treatment is performed during the vapor deposition process, the fluororesin is vapor-deposited while heating the nozzle base material 20. As a result, the liquid-repellent film immediately after being formed on the nozzle base material 20 is heated, so that the heat treatment can be performed at a temperature that does not reach the glass transition point Tg. In this case, a material having relatively low heat resistance can be selected as the material used for the nozzle base material and the intermediate layer.

Next, the Martens hardness and elastic power of the liquid repellent film 40 will be described.

As shown in FIG. 9, the Martens hardness and the elastic power increase with the progress of the annealing and do not change when the annealing is completed, so that they are indicators indicating that the annealing (baking) is properly completed. The Martens hardness and elastic power can be confirmed, for example, with a micro-hardness meter manufactured by Fisher Instruments, Picodenter HM-500.

Here, a method for measuring the minute hardness will be described with reference to FIGS. 10 and 11.

A Vickers indenter having the shape shown in FIG. 10 is used to measure the microhardness. Then, as shown in FIG. 11 (a), the indenter 800 is lowered with respect to the sample 801 (the vapor-deposited film 44 on the nozzle base material 20) at a predetermined speed, and as shown in FIG. 11 (b), the vapor-deposited film. It is pushed to a predetermined depth of 44, held for a predetermined time, and raised at a constant speed as shown in FIG. 11 (c).

For example, the Vickers indenter 800 is pushed in with a force of 9.8 [mN] for, for example, 10 seconds, held for 5 seconds, and pulled out with a constant force for 10 seconds.

A Vickers indenter having a shape defined by JIS Z 2244 can be used, but in this test, a quadrangular pyramid indenter having d1 = d2 = 50 [μm], h = 9.4 [μm], and a facing angle = 136 °. Was used

As a result, for example, as shown in FIG. 12, a profile of the integrated stress Wlast when the Vickers indenter is pushed in and the integrated stress Welast when the test load is unloaded can be obtained. Therefore, the Martens hardness and the elastic power are calculated from these profiles. Martens hardness is the hardness measured under a test load, and is obtained from the load-pushing depth when the load increases.

In this case, the Martens hardness is Fmax / (26.43 × (hmax) ² ), and the elastic power is Welast / (Welast + Wblast) × 100%, which is a characteristic value defined by the equation.

Fmax is the maximum pushing load, and hmax is the maximum pushing amount of the indenter. Further, Wlast: plastic deformation work amount and Welast: elastic deformation work amount.

The higher the elastic power, the smaller the hysteresis loss (plastic deformation), that is, the higher the rubber property, and the smaller the wear due to wiping. If the elastic power is too low, it will be closer to glass than rubber.

The Martens hardness of the present invention is 100 N / mm ² or more, more preferably 130 N / mm ² or more. The elastic power of the present invention is 20% or more, more preferably 25% or more.

In this way, the fluororesin is baked at the glass transition temperature Tg so that the Martens hardness of the liquid-repellent film is 100 N / mm ² or more and the elastic power is 20% or more, thereby improving the liquid repellency and adhesion. Can be improved.

That is, the "sparse" portion inside the vapor-deposited film 44 is sufficiently reduced, and the surface roughness of the liquid-repellent film 40 is reduced, so that the liquid-repellent film 40 exhibits high liquid-repellent properties. Further, by baking at a temperature equal to or higher than the glass transition point Tg, the movement of the molecular chains is activated, and the same molecular chains or the molecules of the underlying layer (nozzle base material 20 or intermediate layer 30) are entangled with each other. , Destruction inside and at the interface of the film when subjected to external stress is suppressed, and the abrasion resistance of the film (adhesion of the film) is improved.

Further, it is said that the "sparse" portion inside the vapor-deposited film 44 is sufficiently reduced by annealing the sparse portion 550 contained in the vapor-deposited film 44 immediately after vapor deposition, as shown in FIG. 13 (a). As shown in FIG. 13B, the amount is reduced and the surface of the liquid-repellent film 40 becomes flat.

Next, the relationship between the Martens hardness of the liquid-repellent film, the elastic power and the adhesion will be described with reference to Tables 1 to 3 and FIGS. 14 to 17.

The peeling load from the scratch test is used as an index of adhesion. Specifically, using an ultra-thin scratch tester (CSR-2000 manufactured by Reska), a stylus with a tip R = 15 μm is brought into contact with the film and pressurized from 0 mN to cause scratches or peeling on the film surface. The load is the peeling load. The larger the peeling load, the higher the adhesion. This index matches very well with the durability in the actual machine test.

Here, Teflon (registered trademark) AF2400 and AF1600 are used as fluororesins, and the measurement results of Martens hardness (HM) for each bake temperature are shown in Table 1, and the measurement results of elastic power (ηIT) for each bake temperature are shown in Table 1. (Calculation results) are shown in Table 2, and the measurement results of the peeling load are shown in Table 3.

The relationship between the Martens hardness and the peeling load for each bake temperature when Teflon (registered trademark) AF2400 is used is shown in FIG. 14, and the relationship between the elastic power and the peeling load for each bake temperature is also shown in FIG. There is.

Further, FIG. 16 shows the relationship between the Martens hardness and the peeling load for each bake temperature when Teflon (registered trademark) AF1600 is used, and FIG. 17 shows the relationship between the elastic power and the peeling load for each bake temperature. There is.

From these results, it can be seen that the Martens hardness and elastic power of the liquid-repellent film correlate with the adhesion.

When Teflon (registered trademark) AF1600 is used as the fluororesin, when the liquid-repellent film is baked at the glass transition temperature Tg (160 ° C.), the Martens hardness of the liquid-repellent film after baking is 128 N / mm ² , which is elastic. The work rate is 24%, and by baking at a temperature of Tg or more, the Martens hardness can be 100 N / mm ² or more, and the elastic work rate can be 20% or more.

When Teflon (registered trademark) AF2400 is used as the fluororesin, when the liquid-repellent film is baked at the glass transition temperature Tg (240 ° C.), the Martens hardness of the liquid-repellent film after baking is 135 N / mm ² , which is elastic. The work rate is 25%, and by baking at a temperature of Tg or more, the Martens hardness can be 100 N / mm ² or more, and the elastic work rate can be 20% or more.

Next, a specific example will be described.

[Nozzle base material]
A metal flat plate member made of SUS316L having a length of 30 mm, a width of 15 mm, and a thickness of 0.05 mm was punched from the side opposite to the liquid discharge surface. The punch used for drilling has a cylindrical tip having a length of 10 μm and a diameter of 20 μm. The burrs generated on the liquid discharge surface side were removed by polishing.

As a result, the diameter of the cylindrical portion 21a on the liquid discharge surface side is 20 μm, the diameter of the opening of the truncated cone-shaped portion 21b on the surface opposite to the liquid discharge surface is 40 μm, and the height of the cylindrical portion 21a is 10 μm. A nozzle base material 20 in which 384 pieces of 21 were formed was obtained.

[Liquid repellent film]
Tetrafluoroethylene perfluorodioxol copolymer (Teflon (registered trademark) AF2400: manufactured by DuPont) is placed on the liquid discharge surface side of the nozzle base material 20 in a high vacuum of ^{1.5 to 8.0 × 10 -3 Pa.} Below, it was heated to 350 to 420 ° C., and vacuum-deposited until the thickness of the vapor-deposited film was about 1 to 3 μm at the portion facing the vapor deposition source.

The obtained thin-film film 44 was baked at a temperature equal to or higher than the glass transition point Tg of the fluororesin to form a fluororesin film 40 that became a dense, smooth-surfaced liquid-repellent film 40.

Similarly, as shown in Table 1, the nozzle plates of Examples 1 to 9 and Comparative Examples 1 to 5 were produced by changing the material and the temperature (presence or absence of baking, temperature).

Then, the Martens hardness and elastic power were measured for each of the nozzle plates of Examples 1 to 9 and Comparative Examples 1 to 5. The results are shown in Table 1.

[Evaluation of wiping durability]
The wiping durability using the evaluation device shown in FIG. 18 was evaluated. Specifically, the nozzle plate 1 is fixed to the fixing jig 602, the wiper 611 is fixed to the fixing jig 612, and the nozzle plate 1 is wiped against the surface of the liquid-repellent film 40 in the container 601 containing the ink 610. (Wipe) operation was performed.

As the ink 610, GX Cartridge Black GC21K, which is an inkjet ink for RICOH GX-3000 manufactured by Ricoh Co., Ltd., was used.

<Injection bending evaluation>
A liquid discharge head including the nozzle plates 1 of Examples 1 to 9 and Comparative Examples 1 to 5 was configured and mounted on an IPSiO G515 manufactured by Ricoh Co., Ltd. to evaluate injection bending. The evaluation is made by printing the nozzle check pattern in the state before the wiping durability test (before the durability test) and after the wiping durability test is performed 10,000 times (after the durability test). The nozzle check pattern was visually observed to evaluate the presence or absence of injection bending.

The evaluation results are shown in Table 4. In Table 4, "Δ" means that the value is within a range that does not cause a problem in actual use, and "x" means that the bending is such that it cannot withstand actual use. “○” means that there is less injection bending than “△”, and “◎” means that there is less injection bending than “○”.

Next, an example of the liquid discharge head according to the present invention will be described with reference to FIGS. 19 and 20. FIG. 19 is a cross-sectional explanatory view of the head in a direction orthogonal to the nozzle arrangement direction (longitudinal direction of the liquid chamber), and FIG. 20 is a cross-sectional explanatory view of the head in the nozzle arrangement direction (short side of the liquid chamber).

In this liquid discharge head, the nozzle plate 101 according to the present invention, the flow path plate 102, and the diaphragm member 103 made of a thin film member as a wall surface member are laminated and joined. A piezoelectric actuator 111 that displaces the diaphragm member 103 and a frame member 120 as a common liquid chamber member are provided.

An individual liquid chamber 106 through which a plurality of nozzles 104 for discharging liquid are communicated by a nozzle plate 101, a flow path plate 102, and a diaphragm member 103, a fluid resistance unit 107 for supplying liquid to the individual liquid chamber 106, and a fluid resistance unit 107. It constitutes a liquid introduction unit 108 leading to the above.

Then, the liquid is supplied from the common liquid chamber 110 as the common flow path of the frame member 120 to the individual liquid chamber 106 through the supply port 109 formed in the diaphragm member 103, through the liquid introduction portion 108 and the fluid resistance portion 107. A filter may be provided at the supply port 109.

The diaphragm member 103 is a wall surface member that forms the wall surface of the individual liquid chamber 106 of the flow path plate 102. The diaphragm member 103 has a three-layer structure, and a deformable vibration region (diaphragm) 130 is formed in a portion corresponding to the individual liquid chamber 106 in one layer on the flow path plate 102 side.

Then, on the side of the diaphragm member 103 opposite to the individual liquid chamber 106, an actuator means for deforming the vibration region 130 of the diaphragm member 103 and a piezoelectric actuator 111 including an electromechanical conversion element as a pressure generating means are arranged. There is.

The piezoelectric actuator 111 has a plurality of laminated piezoelectric members 112 bonded on the base member 113 with an adhesive, and the piezoelectric members 112 are grooved by half-cut dicing to obtain a required number of piezoelectric members 112. The columnar piezoelectric elements (piezoelectric columns) 112A and 112B are formed in a comb-teeth shape at predetermined intervals.

The piezoelectric elements 112A and 112B of the piezoelectric member 112 are the same, but the piezoelectric element 112A that gives a drive waveform to drive the piezoelectric element 112A and the piezoelectric element 112B that is used as a mere column without giving a drive waveform.

Then, the piezoelectric element 112A is joined to the convex portion 130a, which is an island-shaped thick portion formed in the vibration region 130 of the diaphragm member 103. Further, the piezoelectric element 112B is joined to the convex portion 130b which is a thick portion of the diaphragm member 103.

The piezoelectric member 112 is formed by alternately stacking piezoelectric layers and internal electrodes. The internal electrodes are pulled out to their end faces to provide external electrodes, and the piezoelectric member 112 is flexible for giving a drive signal to the external electrodes of the piezoelectric element 112A. The FPC 115 as a wiring member is connected.

The frame member 120 is formed by injection molding with, for example, an epoxy resin or polyphenylene sulfide which is a thermoplastic resin, and a common liquid chamber 110 to which a liquid is supplied from a head tank or a liquid cartridge is formed.

In this liquid discharge head, for example, by lowering the voltage applied to the piezoelectric element 112A from the reference potential, the piezoelectric element 112A contracts, the vibration region 130 of the vibrating plate member 103 is pulled, and the volume of the individual liquid chamber 106 expands. As a result, the liquid flows into the individual liquid chamber 106.

After that, the voltage applied to the piezoelectric element 112A is increased to extend the piezoelectric element 112A in the stacking direction, and the vibration region 130 of the diaphragm member 103 is deformed in the nozzle 104 direction to contract the volume of the individual liquid chamber 106. As a result, the liquid in the individual liquid chamber 106 is pressurized, and the liquid is discharged (injected) from the nozzle 104.

Then, by returning the voltage applied to the piezoelectric element 112A to the reference potential, the vibration region 130 of the vibrating plate member 103 is restored to the initial position, the individual liquid chamber 106 expands, and a negative pressure is generated. The liquid is filled from the liquid chamber 110 into the individual liquid chamber 106. Therefore, after the vibration of the meniscus surface of the nozzle 104 is attenuated and stabilized, the operation for the next droplet ejection is started.

The driving method of this head is not limited to the above example (pull-pushing), and pulling or pushing may be performed depending on the driving waveform.

Next, an example of the device for discharging the liquid according to the present invention will be described with reference to FIGS. 21 and 22. FIG. 21 is a plan view of the main part of the device, and FIG. 22 is a side view of the main part of the device.

This device is a serial type device, and the carriage 403 is reciprocated in the main scanning direction by the main scanning moving mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, and the like. The guide member 401 is bridged over the left and right side plates 491A and 491B to movably hold the carriage 403. Then, the carriage 403 is reciprocated in the main scanning direction by the main scanning motor 405 via the timing belt 408 bridged between the drive pulley 406 and the driven pulley 407.

The carriage 403 is equipped with a liquid discharge unit 440 in which the liquid discharge head 404 and the head tank 441 according to the present invention are integrated. The liquid discharge head 404 of the liquid discharge unit 440 discharges liquids of, for example, yellow (Y), cyan (C), magenta (M), and black (K). Further, the liquid discharge head 404 is mounted by arranging a nozzle array composed of a plurality of nozzles in the sub-scanning direction orthogonal to the main scanning direction and directing the discharge direction downward.

The liquid stored in the liquid cartridge 450 is supplied to the head tank 441 by the supply mechanism 494 for supplying the liquid stored outside the liquid discharge head 404 to the liquid discharge head 404.

The supply mechanism 494 includes a cartridge holder 451 which is a filling portion for mounting the liquid cartridge 450, a tube 456, a liquid feeding unit 452 including a liquid feeding pump, and the like. The liquid cartridge 450 is detachably attached to the cartridge holder 451. Liquid is fed from the liquid cartridge 450 to the head tank 441 by the liquid feeding unit 452 via the tube 456.

This device includes a transport mechanism 495 for transporting the paper 410. The transport mechanism 495 includes a transport belt 412, which is a transport means, and a sub-scanning motor 416 for driving the transport belt 412.

The transport belt 412 attracts the paper 410 and transports it at a position facing the liquid discharge head 404. The transport belt 412 is an endless belt, and is hung between the transport roller 413 and the tension roller 414. Adsorption can be performed by electrostatic adsorption, air suction, or the like.

Then, the transport belt 412 orbits in the sub-scanning direction by rotationally driving the transport roller 413 via the timing belt 417 and the timing pulley 418 by the sub-scanning motor 416.

Further, on one side of the carriage 403 in the main scanning direction, a maintenance / recovery mechanism 420 for maintaining / recovering the liquid discharge head 404 is arranged on the side of the transport belt 412.

The maintenance / recovery mechanism 420 is composed of, for example, a cap member 421 that caps the nozzle surface (the surface on which the nozzle is formed) of the liquid discharge head 404, a wiper member 422 that wipes the nozzle surface, and the like.

The main scanning movement mechanism 493, the supply mechanism 494, the maintenance / recovery mechanism 420, and the transport mechanism 495 are attached to a housing including the side plates 491A and 491B and the back plate 491C.

In this device configured in this way, the paper 410 is fed onto the transport belt 412 and sucked, and the paper 410 is transported in the sub-scanning direction by the orbital movement of the transport belt 412.

Therefore, by driving the liquid discharge head 404 in response to the image signal while moving the carriage 403 in the main scanning direction, the liquid is discharged to the stopped paper 410 to form an image.

As described above, since this device includes the liquid discharge head according to the present invention, it is possible to stably form a high-quality image.

Next, another example of the liquid discharge unit according to the present invention will be described with reference to FIG. FIG. 23 is an explanatory plan view of a main part of the unit.

This liquid discharge unit includes a housing portion composed of side plates 491A, 491B and a back plate 491C, a main scanning movement mechanism 493, a carriage 403, and a liquid among the members constituting the device for discharging the liquid. It is composed of a discharge head 404.

A liquid discharge unit may be configured in which at least one of the above-mentioned maintenance / recovery mechanism 420 and the supply mechanism 494 is further attached to, for example, the side plate 491B of the liquid discharge unit.

Next, still another example of the liquid discharge unit according to the present invention will be described with reference to FIG. 24. FIG. 24 is a front explanatory view of the unit.

This liquid discharge unit includes a liquid discharge head 404 to which the flow path component 444 is attached, and a tube 456 connected to the flow path component 444.

The flow path component 444 is arranged inside the cover 442. A head tank 441 may be included instead of the flow path component 444. Further, a connector 443 that electrically connects to the liquid discharge head 404 is provided on the upper part of the flow path component 444.

In the present application, the liquid to be discharged may have a viscosity and surface tension that can be discharged from the head, and is not particularly limited, but the viscosity becomes 30 mPa · s or less at room temperature, under normal pressure, or by heating or cooling. It is preferable that it is a thing. More specifically, solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, resins, functionalizing materials such as surfactants, biocompatible materials such as DNA, amino acids and proteins, and calcium. , Solvents, suspensions, emulsions, etc. containing edible materials such as natural pigments, etc., for example, inks for inkjets, surface treatment liquids, constituents of electronic elements and light emitting elements, and formation of electronic circuit resist patterns. It can be used for applications such as liquids for three-dimensional modeling.

Piezoelectric actuators (laminated piezoelectric elements and thin-film piezoelectric elements), thermal actuators that use electrothermal conversion elements such as heat-generating resistors, and electrostatic actuators that consist of a vibrating plate and counter electrodes are used as energy sources for discharging liquid. Includes what to do.

The "liquid discharge unit" is a liquid discharge head integrated with functional parts and a mechanism, and includes an aggregate of parts related to liquid discharge. For example, the "liquid discharge unit" includes a combination of at least one of a head tank, a carriage, a supply mechanism, a maintenance / recovery mechanism, and a main scanning movement mechanism with a liquid discharge head.

Here, "integration" means, for example, a liquid discharge head and a functional component, a mechanism in which the mechanism is fixed to each other by fastening, adhesion, engagement, etc., or one in which one is movably held with respect to the other. Including. Further, the liquid discharge head, the functional parts, and the mechanism may be detachably attached to each other.

For example, as a liquid discharge unit, there is one in which a liquid discharge head and a head tank are integrated. In addition, there are some that are connected to each other by a tube or the like to integrate the liquid discharge head and the head tank. Here, a unit including a filter can be added between the head tank of these liquid discharge units and the liquid discharge head.

Further, as a liquid discharge unit, there is a liquid discharge head and a carriage integrated.

Further, as a liquid discharge unit, there is a liquid discharge head in which the liquid discharge head and the scanning movement mechanism are integrated by holding the liquid discharge head movably by a guide member forming a part of the scanning movement mechanism. In some cases, the liquid discharge head, the carriage, and the main scanning movement mechanism are integrated.

Further, as a liquid discharge unit, there is a carriage to which a liquid discharge head is attached, in which a cap member which is a part of the maintenance / recovery mechanism is fixed, and the liquid discharge head, the carriage, and the maintenance / recovery mechanism are integrated. ..

Further, as a liquid discharge unit, there is a liquid discharge unit in which a tube is connected to a head tank or a liquid discharge head to which a flow path component is attached, and the liquid discharge head and a supply mechanism are integrated. Through this tube, the liquid of the liquid storage source is supplied to the liquid discharge head.

The main scanning movement mechanism shall also include a single guide member. Further, the supply mechanism includes a single tube and a single loading unit.

The "device for discharging a liquid" includes a device provided with a liquid discharge head or a liquid discharge unit and driving the liquid discharge head to discharge the liquid. The device for discharging the liquid includes not only a device capable of discharging the liquid to a device to which the liquid can adhere, but also a device for discharging the liquid into the air or the liquid.

The "device for discharging the liquid" may include means for feeding, transporting, and discharging paper to which the liquid can be attached, as well as a pretreatment device, a posttreatment device, and the like.

For example, as a "device that ejects a liquid", an image forming apparatus that ejects ink to form an image on paper, and a three-dimensional object (three-dimensional object) are formed in layers in order to form a three-dimensional object. There is a three-dimensional modeling device (three-dimensional modeling device) that discharges the modeling liquid into the powder layer.

Further, the "device for discharging a liquid" is not limited to a device in which a significant image such as characters and figures is visualized by the discharged liquid. For example, those that form patterns that have no meaning in themselves and those that form a three-dimensional image are also included.

The above-mentioned "material to which a liquid can adhere" means a material to which a liquid can adhere at least temporarily, such as one that adheres and adheres, and one that adheres and permeates. Specific examples include paper, recording paper, recording paper, film, recording media such as cloth, electronic substrates, electronic components such as piezoelectric elements, powder layers (powder layers), organ models, and media such as inspection cells. Yes, including anything to which the liquid adheres, unless otherwise specified.

The material of the above-mentioned "material to which liquid can be attached" may be paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics or the like as long as the liquid can be attached even temporarily.

Further, the "device for discharging the liquid" includes, but is not limited to, a device in which the liquid discharge head and the device to which the liquid can adhere move relatively. Specific examples include a serial type device that moves the liquid discharge head, a line type device that does not move the liquid discharge head, and the like.

In addition, as a "device for ejecting a liquid", a treatment liquid coating device for ejecting a treatment liquid to a paper in order to apply the treatment liquid to the surface of the paper for the purpose of modifying the surface of the paper, etc. There is an injection granulation device that granulates fine particles of the raw material by injecting a composition liquid in which the raw material is dispersed in a solution through a nozzle.

In addition, image formation, recording, printing, printing, printing, modeling, etc. in the terms of the present application are all synonymous.

1 Nozzle plate 11 Nozzle 20 Nozzle base material 21 Nozzle hole 30 Intermediate layer 40 Liquid repellent film 101 Nozzle plate 102 Flow path plate 103 Vibrating plate member 104 Nozzle 106 Individual liquid chamber 110 Common liquid chamber 112 Hydraulic member 120 Frame member 403 Carrying 404 Liquid Discharge head 440 Liquid discharge unit

Claims (11)

A nozzle plate having a nozzle for discharging a liquid and having a liquid-repellent film at least on the surface on the liquid discharge surface side.
The liquid-repellent film is a film containing a fluororesin having a fluorine-containing heterocyclic structure having an ether bond in a PTFE skeleton, and has a Martens hardness of 100 N / mm2 or more and an elastic power of 20% or more on the surface of the film. Fluorine
There is a relationship of c <d between the number average molecular weight c of the fluororesin at the interface with the substrate in the liquid-repellent film and the number average molecular weight d of the fluororesin on the outermost surface of the film. A nozzle plate characterized by. The liquid-repellent film has a slope region in the outer peripheral portion of the nozzle that is inclined in a direction in which the film thickness becomes thinner toward the nozzle.
The nozzle plate according to claim 1, wherein the surface of the liquid-repellent film is flat in a region other than the slope region. The relationship between the average film thickness m of the film thickness of the liquid repellent film on the circumference 5 μm away from the edge of the nozzle in the direction opposite to the center of the nozzle on the normal line of the edge and the standard deviation σ of the film thickness is as follows. The nozzle plate according to claim 1 or 2, wherein σ / m <0.1. The nozzle plate according to any one of claims 1 to 3 , wherein the nozzle base material and the liquid repellent film are in close contact with each other via a silane coupling agent layer. The nozzle plate according to claim 4 , wherein the silane coupling agent layer is a silane coupling agent layer having an amino group. The nozzle plate according to any one of claims 1 to 5 , wherein the film thickness of the liquid-repellent film on the liquid discharge surface side is in the range of 1 μm or more and 3 μm or less. A liquid discharge head comprising the nozzle plate according to any one of claims 1 to 6. A liquid discharge unit including the liquid discharge head according to claim 7. A head tank that stores the liquid to be supplied to the liquid discharge head, a carriage on which the liquid discharge head is mounted, a supply mechanism that supplies the liquid to the liquid discharge head, a maintenance / recovery mechanism that maintains and recovers the liquid discharge head, and the liquid. The liquid discharge unit according to claim 8 , wherein at least one of the main scanning moving mechanisms for moving the discharge head in the main scanning direction is integrated with the liquid discharge head. Liquid discharge head according to claim 7, or apparatus that ejects a liquid, characterized in that it comprises a liquid discharge unit according to claim 8 or 9. The method for manufacturing a nozzle plate according to any one of claims 1 to 6.
A step of forming a film of the fluororesin on a metal nozzle base material provided with the nozzle holes by a vapor deposition method, and
A method for manufacturing a nozzle plate, which comprises a step of heat-treating the fluororesin film at a temperature equal to or higher than the glass transition point Tg.

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