JP2007175920A - Method for molding structure and nozzle plate for liquid discharging head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for molding a minute structure efficiently at a low cost. <P>SOLUTION: The method for molding a structure having a transferred cavity shape by packing a molten molding material which is cured by cooling in the cavity of a mold and by cooling the material includes: a mold heating process for heating a first mold, a second mold, and a minute mold which forms the cavity of the mold by intruding into a space formed by clamping the first and second molds to a temperature of at least the thermal deformation temperature of the molding material; a molding material packing process for packing the molding material in a space which is larger than the cavity formed by the retreat of the minute mold to a first position; a minute mold moving process for moving the minute mold from the first position to a second position forming the cavity; and a cooling process for cooling the molding material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for forming a structure and a nozzle plate for a liquid discharge head formed using the method.

  In recent years, there has been an increasing demand for fine processing in all fields. Among them, there is a demand for a technique for providing fine holes in a film-like or thin-plate-like resin for the purpose of generating fine droplets. For example, an ink jet recording head that is an example of a liquid discharge head generally includes fine ink discharge holes, an ink flow path, and a discharge energy generating element provided in a part of the ink flow path. A film-like or thin-plate-like member constituting this ink jet recording head is formed by arranging a plurality of nozzles that have ink discharge holes on one end and the other end leading to an ink flow path. It is called.

  As a method of forming the nozzle of the nozzle plate, for example, in an ink jet recording head in which a chamber plate having nozzles and ink chambers is manufactured by injecting resin into a mold, an elastic member is formed at a nozzle hole forming portion of the mold. There is a method of performing injection molding after abutting an abutting mold made of the material (see, for example, Patent Document 1).

In addition, in an ink jet head having an ink jet nozzle and using an ink using a glycol-based derivative as a solvent, the material is any of liquid crystal polymer, polyacetal, polyphenylene sulfide, polyphenylsulfone, and polyphthalamide. There is a method in which a nozzle plate is molded by an injection molding method using such a material, and an ink ejection port is formed by an excimer laser (for example, see Patent Document 2).
JP 2000-71459 A JP-A-6-344563

  However, in the prior art in Patent Document 1, when the mold of the elastic member and the nozzle hole forming portion of the opposite mold are in contact with each other, the elastic member is elastically deformed so that no gap is generated between the molds. The mold may be damaged quickly because it must be given a certain pressure. When the mold is damaged, it is necessary to manufacture the mold each time, and the work becomes complicated. Further, even when the nozzle diameter is made smaller (for example, about 10 μm), it is necessary to press the elastic member, and the nozzle forming portion that becomes thinner and more brittle than before is easily damaged. Furthermore, when an injection molding machine is used, if the nozzle hole diameter becomes as small as about 10 μm, a high injection pressure is required to allow the resin to flow into the nozzle details. There is a problem that the nozzle forming portion is damaged by high pressure. In particular, it becomes difficult to meet the demand for a high-density nozzle head in which a plurality of rows having a plurality of minute nozzles are provided.

  Further, in Patent Document 2, an excimer laser processing apparatus used for processing an ink ejection port of a nozzle is a very expensive apparatus, and the production cost is high because the energy consumption is very large.

  This invention is made | formed in view of said subject, The place made into the objective is to provide the shaping | molding method which manufactures a microstructure efficiently at low cost.

  Said subject is solved by the following structures.

1. In a molding method of a structure having a shape in which a molding material in a molten state that is cured by cooling is filled in a void of a molding die, and the molding material is cooled to transfer the shape of the void.
The first mold, the second mold, and the space between the first mold and the second mold are inserted into the space formed by clamping, thereby forming the gap of the molding mold. A mold heating step for heating the fine mold to a temperature equal to or higher than the thermal deformation temperature of the molding material;
A molding material filling step of filling a molding material into a space wider than the gap formed by the fine mold retracting to the first position;
A fine mold moving step of moving the fine mold from a first position to a second position forming the gap;
A cooling step for cooling the molding material;
A method for forming a structure, comprising:

  2. 2. The method of forming a structure according to 1, further comprising a fine mold retreating step of retracting the fine mold from the second position in the direction of the first position after the cooling step.

  3. The method for molding a structure according to 1 or 2, wherein the molding material is any one of a thermoplastic resin, glass, or metal.

4). The structure has a plate shape having holes in the thickness direction of the structure,
The tip of the fine mold that enters the space to form the hole is a plane,
The mold surface of the first mold or the second mold with respect to the tip of the fine mold is a plane,
The tip and the mold surface at the second position of the fine mold are in contact with or have a gap,
A nozzle plate for a liquid discharge head, which is formed by the method for forming a structure according to any one of 1 to 3.

  5. 5. The nozzle plate for a liquid ejection head according to 4, wherein the hole has a diameter of 1 μm or more and 30 μm or less.

  In the first aspect of the invention, after the molten molding material is injected and filled into the space formed by the first mold, the second mold, and the retreating fine mold, the fine mold By intruding into the previous space, a void is formed, and a structure in which the shape of the void is transferred is formed.

  When the molding material is filled, each mold is heated to a temperature higher than the heat deformation temperature of the molding material. Therefore, the molding material filled in the molten state does not impair the fluid state in the space inside the mold. Can be easily filled.

  In addition, since the fine mold is retracted, the fine mold is hardly subjected to the force of the injected resin, and therefore is not damaged, and the usage period of the fine mold can be extended. . In addition, since the fine mold is retracted, the molding material to be injected can be easily and uniformly filled because the fine mold does not prevent the inflow into the space.

  Furthermore, by cooling the first mold, the moving mold, and the fine mold, the molded structure is cooled and cured to a state where it is easy to handle without causing inconvenient deformation at the time of removal. Can do.

  Therefore, it is possible to provide a molding method for efficiently molding the structure at a low cost.

  In the invention described in claim 4, in addition to the above-mentioned effect, when forming a plate-like structure having holes in the thickness direction, the tip of the fine mold for forming the holes is a flat surface, and the gold against the tip is formed. The mold surface is also a flat surface, and the tip of the fine mold at the second position and the previous mold surface are in contact with each other or have a gap. Therefore, the tip of the fine mold for forming the hole is not brought into contact with the corresponding mold surface, so that it is not damaged and the service life of the fine mold can be extended. Moreover, the hole which has the opening as the planar shape of the front-end | tip of a fine metal mold | die can be provided.

  Accordingly, it is possible to provide a nozzle plate for a liquid discharge head that is efficiently formed at low cost.

  An example of an embodiment according to the present invention will be described below by taking as an example the manufacture of a nozzle plate in the ink jet recording head (hereinafter referred to as recording head) shown in FIG.

  First, the configuration of the recording head will be described with reference to FIG. The recording head A includes a nozzle plate 1, a body plate 2, and a piezoelectric element 3.

  A plurality of nozzles 11 for discharging ink are arranged on the nozzle plate 1. Further, the nozzle plate 1 is bonded to the body plate 2 so that the pressure chamber groove 24 serving as a pressure chamber, the ink supply path groove 23 serving as an ink supply path, the common ink chamber groove 22 serving as a common ink chamber, and the ink. A supply port 21 is formed.

  And the flow path unit M is formed by bonding the nozzle plate 1 and the body plate 2 so that the nozzle 11 of the nozzle plate 1 and the pressure chamber groove 24 of the body plate 2 correspond one-to-one. Hereafter, the reference numerals of the pressure chamber groove, the supply path groove, and the common ink chamber groove used in the above description are also used for the pressure chamber, the supply path, and the common ink chamber, respectively.

  The recording head A is completed by adhering the piezoelectric element 3 to the flow path unit M on the back surface of the bottom portion of each pressure chamber 24 opposite to the surface to which the nozzle plate 1 of the body plate 2 is adhered. A driving pulse voltage is applied to each piezoelectric element 3 of the recording head A, and vibration generated from the piezoelectric element 3 is transmitted to the bottom of the pressure chamber 24, and the pressure in the pressure chamber 24 is changed by the vibration of the bottom. Ink droplets are ejected from the nozzle 11.

  Here, FIG. 2 shows one pressure chamber 24 in the cross section at the position of YY ′ of the nozzle plate 1 and XX ′ of the body plate 2 in the recording head A and the vicinity of the nozzle 11 communicating therewith. Is schematically shown. The shape of the nozzle 11 includes a cylindrical portion 11a and a conical portion 11b. The shape of the nozzle 11 is not particularly limited and may be any shape that can be easily released during molding. For example, the nozzle 11 may have a cylindrical shape or a shape having a taper as described above. Further, the cross-sectional shape of the nozzle 11 need not be limited to a circle, and may be a polygon or the like instead of a circle. The diameter when the cross-sectional shape is not a circle is the diameter when the cross-sectional area of the target cross-section is replaced with a circle having the same area.

  The forming of the nozzle plate 1 having a plurality of nozzles 11 shown in FIG. 2 will be described. FIG. 3 is a view schematically showing a mold used for molding the nozzle plate 1 by injection molding and its periphery.

  The mold is composed of a fixed mold 302 as a first mold, a movable mold 301 as a second mold, and a fine mold 303. For the molding material filled into the cavity 310 through the gate 307, the plate shape of the nozzle plate is formed by the fixed mold 302 and the movable mold 301, and the nozzle 11 is formed by the fine mold 303 extruded into the cavity 310. It is supposed to be. The movable mold 301 and the fine mold 303 are movable. When the movable mold 301 is moved, the movable mold 301 is moved together with the fine mold 303, and the fine mold 303 is movable independently. ing.

  Here, the state shown in FIG. 3 shows a state immediately before the molding material is injected into the cavity 310. From this state, the molding material is filled into the cavity 310 through the gate 307, and then the retracted fine mold 303 is advanced to compress the molding material filled in the cavity 310. As the molding material, a thermoplastic resin, glass or metal is used. Moreover, the material of the molding die used when these are used as the molding material is not particularly limited, and may be appropriately selected according to the molding material.

  Hereinafter, the molding material will be described as a thermoplastic resin. As specific thermoplastic resins (hereinafter referred to as resins), for example, PP (polypropylene), PET (polyethylene terephthalate), PMMA (polymethyl methacrylate), PC (polycarbonate), PE (polyethylene), PVC (polychlorinated) Vinyl).

  The diameter (hereinafter referred to as the nozzle diameter) of the end surface of the cylindrical portion 11a (see FIG. 2) of the nozzle 11 from which droplets such as ink formed by the nozzle forming portion 303a provided in the fine mold 303 are ejected. ) Is preferably 1 μm or more and 30 μm or less. By setting the nozzle diameter to 1 μm or more and 30 μm or less, the nozzle plate 1 having this nozzle diameter can cope with high-definition recording and can be manufactured at low cost with good productivity.

  FIG. 4 schematically shows a process of injection-molding the nozzle plate 1 using the molding die composed of the fixed die, the movable die and the fine die shown in FIG. FIG. 4A shows the state immediately before the resin as the molding material is injected, focusing on the mold part, omitting the periphery of the mold and the gate, as in the state shown in FIG.

Each of the fixed mold 302, the movable mold 301, and the fine mold 303 is heated, and the temperature at which these molds are heated is the melt injected into the cavity 310. It is preferable that the temperature be equal to or higher than the heat distortion temperature of the resin in the state. Here, the thermal deformation temperature is specified by JIS K7207 (load 4.5 × 10 ⁵ Pa deflection temperature). In addition, the upper limit temperature at which the mold is heated is practically preferably not higher than the melting point of the injected resin.

  The method for heating the mold is not particularly limited, and for example, known water, oil, steam, or the like may be used. By setting these molds to a state heated above the heat deformation temperature, the injected resin 320 does not decrease in fluidity to a state where it is difficult to flow in the cavity 310 inside the mold. It is easily injected and filled into the cavity 310 (FIG. 4B).

  When the resin 320 is injected and filled at a high injection pressure, as shown in FIG. 4B, the fine mold 303 is retracted to a position where it is difficult to receive the resin injection pressure. Since the fine mold 303 is retracted in this way, the nozzle molding portion 303a of the fine mold 303 is hardly damaged by the injected resin, and thus is not damaged. Therefore, the fine mold 303 can be used for a long time.

  In addition, since the nozzle molding portion 303 a of the fine mold 303 is retracted, the injected resin 320 can be easily filled into the cavity 310 without being hindered from flowing into the cavity 310. As shown in FIG. 4B, the position where the fine mold 303 is retracted does not necessarily need to be such that the nozzle molding portion 303a is completely retracted from the cavity 310, and the shape of the nozzle, What is necessary is just to decide suitably by the molding material injected, the injection pressure of a molding material, etc.

  Next, molten resin is injected and filled into the cavity 310 formed by the movable mold 301 and the fixed mold 302, and the fine mold 303 is further advanced into the cavity 310 (FIG. 4C). By compressing and molding the filled resin, the shape of the nozzle forming portion 303a is transferred to the filled resin (FIG. 4D)). Since the movable mold 301, the fixed mold 302, and the fine mold 303 are heated to a temperature higher than the thermal deformation temperature of the filled resin, the fine mold 303 can easily advance into the cavity 310. It can be.

  It is preferable that the tip of the nozzle molding portion 303a where the fine mold 303 moves forward to form a nozzle is a flat surface, and the surface of the fixed mold 302 facing the tip is a flat surface. Is more preferable.

  Further, the gap between the tip of the nozzle forming portion 303a formed by stopping the fine mold 303 and the fixed mold 302 is preferably about 0 to 10 μm depending on the material to be injected. For example, in the case of PET (polyethylene terephthalate), it is preferably 0 μm or more and 2 μm or less, and in the case of PP (polypropylene), it is preferably 0 μm or more and 2 μm or less. This gap may be caused, for example, by providing a position control device in the movement mechanism (extrusion mechanism) of the fine mold 303, or the movable mold 301 on the opposite side of the cavity 310 when the fine mold 303 is pushed out. Alternatively, a gap adjusting plate 304 may be provided between the metal mold 303 and the fine mold 303, and the thickness of the gap adjusting plate 304 may be adjusted (contact surface adjustment). When the advance amount of the fine mold 303 is adjusted at the contact surface, a spring 331 or the like is provided between the fine mold 303 and the moving mechanism 330 that moves the fine mold 303 in order to prevent deformation of the fine mold 303 shown in FIG. It is preferable to provide an elastic member.

  The mechanism through which the nozzle penetrates in a state where a gap is provided between the tip of the fine mold 303 and the fixed mold 302 is not clear, but a very thin film is formed in the gap. Perforation starts from the point where the thin film seems to be weakest, and the range extends outward, and finally extends to the entire range where a very thin film is formed, which is equivalent to the planar shape of the tip of the nozzle It is thought that the micropores of the shape are penetrated.

  Next, the fixed mold 302, the movable mold 301, and the fine mold 303 are cooled using, for example, cooling water. By this cooling, the filled and molded resin 320b is cooled, and can be cured to a state where it can be easily handled without causing an unfavorable deformation at the time of taking out.

  Next, the nozzle plate 320b, which is a molded resin, is taken out. Examples of the procedure for taking out the nozzle plate 320b include the following.

  First, the fine mold 303 is moved backward so that the nozzle plate 320b is held in the cavity 310 between the fixed mold 302 and the movable mold 301 (FIG. 4 (e1)). Next, by opening the fixed mold 302 and the movable mold 301 (FIG. 4 (f1)), for example, an eject mechanism that pushes out an ejector (not shown) without affecting the nozzle plate 320b on the fine mold. Can be easily taken out (FIG. 4G). In this case, since the fine mold 303 has a force to be pulled out only from the resin in the cavity 310 in which the nozzle is formed in the direction in which the nozzle molding portion 303a protrudes, for example, it is perpendicular to the nozzle-shaped mold portion. An external force that pushes the direction down is not applied, and the fine mold 303 is preferable because it is less likely to break and can be used for a longer period of time.

  Further, the movable mold 301 is moved back together with the fine mold 303 along with the nozzle plate 320b (FIG. 4 (e2)). Next, the fine mold 303 is retracted (FIG. 4 (f2)). By retracting the fine mold 303, the nozzle plate 320b can be easily taken out by using an eject mechanism or the like without affecting the fine mold 303 (FIG. 4G). In this case, since the fine mold 303 has a force to be pulled out only from the resin in the cavity 310 in which the nozzle is formed in the direction in which the nozzle molding portion 303a protrudes, for example, it is perpendicular to the nozzle-shaped mold portion. The fine mold 303 is preferable because the external force that pushes down the method is not applied, and the possibility that the fine mold 303 is more damaged is reduced and can be used for a longer period of time.

  In the present embodiment, the nozzle plate for an ink jet recording head is formed as an example. However, the forming method of the present invention is not limited to this, and can be modified without departing from the gist thereof. It has a structure such as a hole having a diameter of about μm to several mm and a groove having the same width and depth. Is possible.

Example 1
The shape of the nozzle is made of polypropylene, which is a thermoplastic resin as a molding material, and a cylindrical portion (nozzle diameter: 10 μm, length: 30 μm) and a tapered portion (length: 170 μm, taper angle: about 5 degrees) as shown in FIG. An example in which 100 nozzle plates having a size of 5 mm × 20 mm and a thickness of 0.2 mm having five nozzles to be formed will be described below. The molding process was in accordance with FIG. 4 (including (e1), (f1), and (g)).

The contact surface gap was adjusted so that the gap between the tip of the nozzle molding portion 303a and the fixed mold 302 when the fine mold 303 was advanced was 0 or more and 3 μm or less, and the result was 1 μm.
The fixed mold 302 and the movable mold 301 were closed, and both molds and the retracted fine mold 303 were heated to 120 ° C. (FIG. 4A). This temperature was determined from the fact that the thermal deformation temperature of the polypropylene used was 95 ° C. to 105 ° C. (catalog value).

  While maintaining the above mold temperature, polypropylene melted at 190 ° C. is injected into the cavity 310 at an injection speed of 30 mm / s and a maximum pressure of 80 MPa (FIG. 4B). did.

  Next, the fine mold 303 was advanced at a maximum pressure of 5 MPa into the cavity 310 at a speed of 0.2 mm / s (FIG. 4C) and stopped at the contact surface (FIG. 4D).

  While the fine mold 303 was stopped, the polypropylene was cured by cooling the mold temperature to 80 ° C. Thereafter, the fine mold 303 is retracted (FIG. 4 (e1)), the fixed mold 302 and the movable mold 301 are opened (FIG. 4 (f1)), and the nozzle plate 320b is taken out from the molding apparatus ( FIG. 4 (g)).

  When the nozzle plate 320b was visually observed at room temperature and the nozzle portion was visually observed using a microscope, a good nozzle hole was formed in the nozzle portion with no non-penetrating portion or partial penetration. In addition, as a result of assembling a recording head using 10 nozzle plates 320b and observing the ink ejection state, there were no inconveniences that caused problems such as unevenness in the interval between ejected droplets and unevenness in the ejection amount of ink.

(Example 2)
100 nozzle plates were manufactured in exactly the same way as in Example 1, except that the nozzle plate to be molded was 2 μm in nozzle diameter, 3 μm in cylinder length, and 197 μm in taper length.

  As with Example 1, the nozzle plate 320b taken out was visually observed with a microscope. As a result, the nozzle portion did not show a non-penetrating portion or a state of partial penetration, and a good nozzle hole was formed. It was. In addition, as a result of assembling a recording head using 10 nozzle plates 320b and observing the ink ejection state, there were no inconveniences that caused problems such as unevenness in the interval between ejected droplets and unevenness in the ejection amount of ink.

It is a figure which shows the structure of the inkjet recording head which has a nozzle plate as an example of embodiment. FIG. 2 is a diagram schematically showing one pressure chamber of the ink jet recording head shown in FIG. 1 and the vicinity of a nozzle communicating with the pressure chamber. It is a figure which shows typically the metal mold | die used in order to shape | mold the nozzle plate which is an example of embodiment by injection molding, and its periphery. It is a figure which shows typically the process of shape | molding a nozzle plate by injection molding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nozzle plate 2 Body plate 3 Piezoelectric element 11 Nozzle 21 Ink supply port 22 Common ink chamber (groove)
23 Ink supply path (groove)
24 Pressure chamber (groove)
11a Cylindrical part 11b Cone part 302 Fixed mold 301 Movable mold 303 Fine mold 303a Nozzle molding part 304 Space adjustment plate 307 Gate 310 Cavity 330 Fine mold moving mechanism 331 Spring A Inkjet recording head M Channel unit

Claims (5)

In a molding method of a structure having a shape in which a molding material in a molten state that is cured by cooling is filled in a void of a molding die, and the molding material is cooled to transfer the shape of the void.
The first mold, the second mold, and the space between the first mold and the second mold are inserted into the space formed by clamping, thereby forming the gap of the molding mold. A mold heating step for heating the fine mold to a temperature equal to or higher than the thermal deformation temperature of the molding material;
A molding material filling step of filling a molding material into a space wider than the gap formed by the fine mold retracting to the first position;
A fine mold moving step of moving the fine mold from a first position to a second position forming the gap;
A cooling step for cooling the molding material;
A method for forming a structure, comprising: 2. The method of forming a structure according to claim 1, further comprising a step of retracting the fine mold from the second position in the direction of the first position after the cooling step. . The method for molding a structure according to claim 1 or 2, wherein the molding material is any one of a thermoplastic resin, glass, or metal. The structure has a plate shape having holes in the thickness direction of the structure,
The tip of the fine mold that enters the space to form the hole is a plane,
The mold surface of the first mold or the second mold with respect to the tip of the fine mold is a plane,
The tip and the mold surface at the second position of the fine mold are in contact with or have a gap,
A nozzle plate for a liquid discharge head, which is formed by the structure forming method according to claim 1. 5. The nozzle plate for a liquid discharge head according to claim 4, wherein a diameter of the hole is 1 μm or more and 30 μm or less.

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