JP2017136708A - Method for creating mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To create a mold formable on-demand, reduced in a load upon release and also high in dimensional accuracy.SOLUTION: Provided is a method for creating a mold, using a polymer solution having a sol-gel transition temperature, formed on a stage 20 in which the polymer solution is not spread. Through a step where a polymer solution held to a temperature lower than a sol-gel transition temperature is discharged to the stage 20 using a droplet discharge mechanism 10, a step where the temperature of the polymer solution discharged to the stage 20 is held to the one higher than the sol-gel transition temperature, and it is gelled, a step where the droplet discharge mechanism 10 and the stage 20 are relatively moved to form a layer of gel with a shape of the locus of the relative movement on the stage 20, and a step where a polymer solution is further discharged to the surface of the layer of the gel by the droplet discharge mechanism 10, the gel is laminated and molded to create a mold.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a mold.

There are two problems when a three-dimensional structure (referred to as a molded product) of a fragile material such as hydrogel or biomaterial is molded with a conventional mold made of metal or plastic.
The first problem is that the on-demand property is low. In order to form a mold, a process of machining a metal or plastic material by cutting or the like is first required. Further, when the shape of the gel to be molded changes, it is necessary to newly manufacture the mold by cutting.
The second problem is that a load due to mold release is applied to the molded product. That is, when removing the molded gel from the mold, there is a possibility that friction occurs between the inner wall of the mold and the molded product, and the molded product is destroyed.

As a method for obtaining a molded product by laminating a temperature-responsive sol-gel transition material, a method described in Patent Document 1 (Japanese Patent Publication No. 2013-542728) is known.
However, in the method disclosed in Patent Document 1, since only a temperature-responsive sol-gel transition material having a high viscosity can be used, a step is generated between the layers due to lamination. Therefore, when used as a mold, the step is transferred to the molded product. Therefore, a mold cannot be created by the method disclosed in Patent Document 1.

  The present invention has been made in view of the above-described conventional problems, and its purpose is to use a temperature-responsive sol-gel material, which can be formed on demand, with a small load at the time of mold release, and dimensional accuracy. Is to make a high mold.

  The present invention uses a polymer solution having a sol-gel transition temperature that is solated at a temperature lower than the sol-gel transition temperature and gels at a temperature higher than the sol-gel transition temperature, and the polymer solution does not wet and spread. The mold is formed on a stage made of a substrate having a contact angle of 5 ° C. under a temperature environment in which the stage or atmosphere is higher than the sol-gel transition temperature, and the temperature is lower than the sol-gel transition temperature. A step of discharging the retained polymer solution to the stage by a droplet discharge mechanism, a step of gelling the polymer solution discharged to the stage while maintaining the temperature at a temperature higher than a sol-gel transition temperature, and the liquid A step of relatively moving the droplet discharge mechanism and the stage so as to form a gel layer on the stage in the shape of the locus of the relative movement; It includes a step of discharging the solution, and that is a template creation method characterized by lamination molding a gel.

  According to the present invention, it is possible to provide a mold that can be formed on demand using a temperature-responsive sol-gel material, has a small load during mold release, and has high dimensional accuracy.

It is a figure which shows roughly the additive manufacturing apparatus which enforces the preparation method of the casting_mold | template concerning the 1st Embodiment of this invention. It is a top view of the casting_mold | template produced with the additive manufacturing apparatus of FIG. It is sectional drawing which cut the casting_mold | template by the line of AB in FIG. It is sectional drawing of the casting_mold | template produced using the polymer solution of higher viscosity than the case of FIG. It is a figure which shows a mode that the polymer solution was discharged on the PET base material whose contact angle is 110 degrees, and a line was drawn by the polymer solution not spreading. It is a figure which shows a mode that the polymer solution was discharged on the base material which a polymer solution spreads in the same discharge conditions as the case of FIG. 5, and the line was drawn. It is a figure which shows roughly the additive manufacturing apparatus which enforces the preparation method of the casting_mold | template concerning the 3rd Embodiment of this invention.

Embodiments of the present invention will be described with reference to the accompanying drawings.
The method for producing a mold according to the present embodiment differs depending on whether the sol-gel transition temperature of the sol-gel transition material used for the mold is higher than the room temperature of the space using the layered manufacturing apparatus described later or lower than the room temperature.
As the room temperature around the apparatus for forming the mold, it is generally assumed that the room temperature range is 20 ± 15 ° C. The room temperature using the additive manufacturing apparatus described later is preferably about 15 to 25 ° C.
Here, the room temperature using the additive manufacturing apparatus is set to 20 ° C.

First Embodiment FIG. 1 is a diagram schematically showing an additive manufacturing apparatus that performs a mold making method according to a first embodiment of the present invention.
The additive manufacturing apparatus 1 includes a droplet discharge mechanism 10 for discharging a polymer solution, a stage 20 for landing the discharged polymer solution, and a drive for relatively moving the droplet discharge means 12 of the droplet discharge mechanism 10 and the stage 20. Unit 30, heating mechanism 22 for heating and polymerizing the discharged polymer solution on stage 20, discharge solution cooling means (here, for example, a Peltier cooling device) 32 for cooling the polymer solution before discharge, and the like Prepare.

Examples of the droplet discharge mechanism 10 include, but are not limited to, a pneumatic dispenser, an ink jet, and a syringe pump. Here, a case where the pneumatic dispenser 35 is used will be described. In this case, for example, a syringe is used as the droplet discharge means 12.
The stage 20 has a flat top surface (including a substantially flat shape).
As the material of the stage 20, it is preferable to use a base material that does not wet the polymer solution and has a contact angle of 90 ° or more. As the substrate, a plastic substrate, a metal subjected to a liquid repellent treatment, or a glass substrate subjected to a liquid repellent treatment is particularly desirable. Examples of the plastic substrate include PET (polyethylene terephthalate), polyimide, PTFE (polytetrafluoroethylene), and the like. However, it is not limited to these.

The heating mechanism 22 is a heater that heats the stage 20, and can maintain the temperature of the upper surface of the stage 20 at or above the sol-gel transition temperature of the polymer solution. Examples of the heating mechanism 22 include, but are not limited to, a conductive heater and a heat exchanger.
The drive unit 30 moves at least one of the droplet discharge means 12 and the stage 20 to relatively move the droplet discharge means 12 and the stage 20 in a three-dimensional direction, and includes a motor, a pneumatic cylinder, and the like. However, it is not limited to this.
The discharge solution cooling means 32 is a means for cooling the polymer solution of the droplet discharge means 12 to a temperature lower than the sol-gel transition temperature to form a sol. Examples of the configuration include, but are not limited to, a Peltier element, ice, a refrigerant, a heat exchanger, and the like.
When the sol-gel transition temperature of the polymer solution to be used is higher than room temperature, the discharge solution cooling means 32 may be omitted. Further, when the sol-gel transition temperature of the polymer solution to be used is lower than room temperature, the heating mechanism 22 may be omitted.

Next, the polymer solution to be discharged will be described.
In the present embodiment, the material forming the mold 40 (FIG. 2) has a sol-gel transition temperature that is solated at a temperature lower than the sol-gel transition temperature and gelled at a temperature higher than the sol-gel transition temperature. A polymer solution is used.
Examples of polymers having a sol-gel transition temperature include 8-arms PEG-block-PLLA-cholesterol conjugate disclosed in Patent Document 2 (Patent No. 5019851) and Patent Document 3 (Patent No. 5264103). Poly [(Glc-Asp) -r-DL-LA] -g-PEG shown in Japanese Patent Publication), PLGA-PEG-PLGA shown in Non-Patent Document 1, and Pluronic (registered trademark) F127. There is a poloxamer 407. However, it is not limited to these.

Here, poloxamer 407 is desirable as a polymer having a sol-gel transition temperature.
Poloxamer 407 (hereinafter referred to as poloxamer) has an example that has been researched and developed for use in a drug delivery system, and is readily available.
The lower the viscosity of the polymer solution is, the higher the dimensional accuracy of the mold 40 is. The viscosity at the time of discharge is preferably 500 mPa · s or less, and particularly preferably less than 150 mPa · s.

If the viscosity at the time of discharging the polymer solution is 500 mPa · s or less, the accuracy of the mold 40 is improved, but the fluidity of the polymer solution is high, and it is difficult to form a layer by spreading on the substrate. . Therefore, a base material having a contact angle of 90 ° or more, which does not allow the polymer solution to wet and spread, is required.
Moreover, if it is 150 mPa * s or less, a precision will improve further, but the fluidity | liquidity of a polymer solution will become still higher. In order to stabilize the flowing amount of the polymer solution when modeling the mold 40, it is necessary to devise a method for keeping the temperature of the atmosphere constant.
In the case of a polymer solution having a high viscosity, particularly when the viscosity at the time of ejection is greater than 500 mPa · s, gelation occurs almost without flowing after ejection, so that wetting and spreading to the substrate is not remarkable. However, a step difference between the layers 42 (FIG. 3) due to stacking described below is a problem, and is not desirable as a material of the mold 40.

In a polymer solution having a high viscosity, since the shape is maintained from when it is discharged until it gels, it gels while maintaining the curvature immediately after discharge. Therefore, a step between the layers 42 due to the lamination remains on the inner wall.
In addition, as a method of discharging a polymer solution having a high viscosity, a dispenser 35 is mainly used. However, when a high-viscosity liquid is discharged by the dispenser 35, it is difficult to discharge a small droplet compared to a low-viscosity liquid. The amount increases. Therefore, when the width of the line to be ejected is the same, the height of the liquid tends to be higher than when a low-viscosity polymer solution is used. .
Therefore, in order to prevent the step from being transferred to the molded product, the viscosity of the polymer solution to be used is preferably 500 mPa · s or less, particularly 150 mPa · s or less.

Next, a method for forming a gel laminate (three-dimensional structure) will be described.
A droplet discharge means 12 containing a sol polymer solution is prepared. Further, the stage 20 made of a base material on which the polymer solution does not spread out is maintained at a temperature equal to or higher than the sol-gel transition temperature of the polymer solution. Then, the following steps are executed. That is,
Step 1. A sol polymer solution is discharged from the droplet discharge means 12 using the droplet discharge mechanism 10.
Step 2. The discharged polymer solution is held on the stage 20 at a temperature equal to or higher than the sol-gel transition temperature and gelled.
Step 3. Using the drive unit 30, the droplet discharge means 12 and the stage 20 are relatively moved in the horizontal direction.

Step 4. A gel layer in the shape of a relative movement locus is formed on the stage 20.
A step of relatively moving a droplet discharge mechanism and the stage to form a gel layer in the shape of the locus of relative movement on the stage;
Step 5. While moving the drive unit 30, the polymer solution is further discharged onto the formed gel layer, and the gel layer is stacked. When the gel layer is formed, a layer including a portion where the gel is not formed is formed by securing a region where the polymer solution is not discharged inside the outer periphery of the layer.
By repeating the step 5, the operation of overlapping the gel layers of the polymer solution is repeated to form a gel molding including a cavity structure.

The discharged polymer solution maintains fluidity until gelation. Therefore, when the polymer solution is further discharged from the top of the gel layer in step 5, the discharged polymer solution flows into the concave / convex concave portions of the gel layer or the edge of the peripheral portion of the gel layer and then the gel. Turn into.
As a result of the examination, it was found that the gelation time suitable for filling the steps between the layers is preferably about 1 second to 1 minute.

Next, a description will be given of the time from when the polymer solution is discharged to gelation, and again from the top until the polymer solution is discharged.
In the present embodiment, the polymer solution gels after a time required for fluidization after being discharged. As described above, the gelation time suitable for filling the unevenness between the layers is preferably about 1 second to 1 minute. That is, if the discharged polymer solution is discharged again from above before gelation, the shape of the gel layer may collapse. For this reason, when the polymer solution is discharged from above onto the same point, it is desirable to leave time for the lower layer to gel. As a result of the examination, the time interval for discharging to the same point is preferably at least 5 seconds. However, the above time may inevitably occur due to the time required for the operation of the apparatus. In this case, it is not necessary to explicitly create a waiting time when stacking.
By the above method, the casting mold 40 having a sol-gel transition temperature is prepared.

Next, the shape of the mold 40 will be described by taking the case where the cylindrical mold 40 is created as an example.
FIG. 2 is a top view of the mold 40. FIG. 3 is a cross-sectional view of the mold 40 taken along the line AB in FIG. 2. In this state, the step shape between the layers 42 due to lamination is removed, and the mold 40 can be used as the mold 40. FIG. 4 is a view similar to FIG. 3, but here is a cross-sectional view of a mold 40 made using a polymer solution having a higher viscosity than that of FIG.
Here, a method for evaluating the level difference of the created mold 40 will be described.
The level difference of the created mold 40 is calculated by, for example, the following processes 1 to 4. That is,
Step 1. A glass scale is applied to the side of the created mold 40, and a photograph is taken with a digital camera from the horizontal direction with respect to the mold 40.
Step 2. The photograph taken is analyzed by a computer, and the number of pixels at the depth of the concave portion of the step formed by the lamination on the side surface of the mold 40 is measured.
Step 3. The number of pixels corresponding to 1 mm of the glass scale in the photograph taken is compared with the number of pixels of the depth of the recess, and the depth of the recess is calculated.
Step 4. Steps 2 to 3 are repeated to calculate the depth of the 10 recesses, and the average value is calculated.

(Specific example 1)
Using a poloxamer 407 aqueous solution whose viscosity at the time of ejection was adjusted to 400 mPa · s, a cylindrical substrate having an inner diameter of 18 mm, an outer diameter of 23 mm, and a height of 17 mm was applied to a PET substrate having a contact angle of 110 ° by a pneumatic dispenser 35. The mold 40 was layered.
As a result, a mold 40 having a depth of a recess of a step between the layers 42 generated by the lamination of 0.38 mm could be produced.

Next, the discharge result of the polymer solution by the base material in which the polymer solution spreads and the base material in which the polymer solution does not spread will be shown.
FIG. 5 is a diagram showing a state in which a line L having a width of 1 cm and a length of 10 cm is drawn by discharging the polymer solution onto a PET base material having a contact angle of 110 ° where the polymer solution is not wetted and spread. FIG. 6 is a diagram illustrating a state in which a line is drawn by discharging the polymer solution onto the base material of the stage 20 where the polymer solution spreads under the same discharge conditions. Here, stainless steel was used as a base material on which the polymer solution spreads. The contact angle was 40 °.
When the polymer solution is discharged onto the substrate spreading wet, the polymer solution spreads irregularly without being proportional to the shape of the drawn line L. Therefore, the first gel layer 42 cannot be formed when trying to laminate-mold the mold 40. For this reason, the mold 40 cannot be formed using a base material on which the polymer solution spreads.
When the polymer solution was discharged on the PET base material and the stainless steel base material under the same discharge conditions, a line that could be formed with a width of 1.0 mm on the PET base material had a width of 3. It was 2 mm.

Next, the case where it shape | molds using the polymer solution with the viscosity at the time of discharge larger than 500 mPa * s is demonstrated.
(Specific example 2)
Here, a cylindrical gel laminate having an inner diameter of 18 mm, an outer diameter of 23 mm, and a height of 17 mm was modeled from an aqueous poloxamer 407 solution having a viscosity at the time of ejection of 1500 mPa · s in the same experimental system as that at 400 mPa · s.
As a result, a gel laminate was obtained in which the depth of the concave portion of the step between the layers 42 caused by the lamination was 1.5 mm.

(Specific example 3)
A poloxamer 407 aqueous solution having a viscosity at the time of discharge of 900 mPa · s was formed into a cylindrical gel laminate having an inner diameter of 18 mm, an outer diameter of 23 mm, and a height of 17 mm in the same experimental system as that at 400 mPa · s.
As a result, the depth of the recessed portion of the step between the layers generated by the lamination became a shaped article having a thickness of 1.2 mm.
According to the study by the present applicant, in order to prevent the step between the layers 42 caused by the lamination from being transferred to the molded product, the viscosity of the polymer solution is preferably 500 mPa · s or less, and the polymer solution In order to form a gel layer, it was found that selecting a base material that does not allow the polymer solution to wet and spread for stage 20 is an essential condition.

Second Embodiment Using the additive manufacturing apparatus 1 shown in FIG. 1, a mold 40 was modeled using the stage 20 as a PTFE base material.
(Concrete example)
That is, a cylindrical mold 40 having the same discharge conditions as in the first embodiment, a viscosity of 400 mPa · s, an inner diameter of 18 mm, an outer diameter of 23 mm, and a height of 17 mm was layered.
As a result, a mold 40 having a contact angle of 130 ° and a depth of the recess of the step between the layers generated by the lamination of 0.38 mm could be produced.
Further, the PTFE base material has a larger contact angle than that of PET, and the first layer base could be finely shaped.
When a single line was drawn on the PET substrate and the PTFE substrate under the same discharge conditions, the width was 1.0 mm on the PET substrate and 0.91 mm on the PTFE substrate.
From the above, it was found that the base of the first layer can be formed finely in the PTFE base material.

Third Embodiment As the polymer material has a lower viscosity, the dimensional accuracy can be improved, but it tends to flow after ejection, and the amount of flow affects the dimensional accuracy.
When the stage 20 is heated as a heating means for gelling the discharged polymer solution, the temperature of the upper layer part tends to be lower than that of the lower layer part. Therefore, when the stack (three-dimensional structure) becomes higher by continuing the stacking, the upper layer portion has a longer time from the discharge of the polymer solution to the gelation, that is, the time for stacking one layer. There is a problem that becomes longer. In this case, the amount of flow of the polymer solution increases.

Therefore, in order to stabilize the time for laminating one layer and stabilize the flowing amount, it is preferable to create the mold 40 with the layered manufacturing apparatus 1 using the following constant temperature bath 50 as the heating mechanism 22. is there.
FIG. 7 is a diagram schematically showing an additive manufacturing apparatus 1 that implements the mold making method according to the third embodiment of the present invention.
In the present embodiment, a thermostatic chamber 50 that makes the atmosphere a temperature environment higher than the sol-gel transition temperature is used.
The additive manufacturing apparatus 1 includes a droplet discharge mechanism 10 for discharging a polymer solution, a stage 20 for landing the discharged polymer solution, and a drive for relatively moving the droplet discharge means 12 of the droplet discharge mechanism 10 and the stage 20. The unit 30 includes a discharge solution cooling means 32 for cooling the polymer solution before discharge, a thermostat 50, and the like.
The thermostat 50 is a device that keeps the temperature of the internal space constant. The set temperature of the thermostatic chamber 50 is set to be higher than the sol-gel transition temperature of the polymer solution and maintained.

The droplet discharge mechanism 10, the stage 20, the drive unit 30, and the discharge solution cooling unit 32 are the same as those in the first embodiment, but in this embodiment, at least the stage 20, the drive unit 30, the discharge solution cooling unit 32, and the liquid The droplet discharge means 12 of the droplet discharge mechanism 10 is accommodated in the constant temperature bath 50.
The means for forming the gel molding is the same as in the first embodiment.
That is, the polymer solution cooled by the discharge solution cooling means 32 is discharged onto the stage 20. Since the space temperature in the stage 20 and the thermostat 50 is higher than the sol-gel transition temperature, the discharged polymer solution gels.

In the present embodiment, since the shaped object is heated using the thermostatic chamber 50, there is no problem that the temperature of the upper layer portion becomes low at the time of stacking, and the waiting time for stacking for one layer can be made constant even if the stacking continues to be high.
(Concrete example)
Using an aqueous solution of poloxamer 407 having a viscosity of 150 mPa · s, a concave part of a step between layers generated by lamination as a result of laminating a cylindrical mold 40 having an inner diameter of 18 mm, an outer diameter of 23 mm, and a height of 17 mm on a PTFE substrate with a dispenser 35 A mold 40 having a depth of 0.27 mm could be produced.

As mentioned above, although embodiment of this invention was described, the effect is summarized and described below. That is, in this embodiment,
(1) Since the mold is formed on a stage where the polymer solution is not wetted and spread, the foundation is stable and the dimensional accuracy of the mold is increased.
(2) When the viscosity of the polymer solution is 500 mPa · s or less, the fluidity is enhanced and the smoothness of the mold is enhanced.

(3) Since the base material for the stage is plastic, liquid-repellent-treated glass, liquid-repellent-treated metal, or a combination thereof, the polymer solution does not spread on the stage, the base is stable, the mold Dimensional accuracy increases.
(4) Discharge after the polymer solution in the lower layer has gelled by leaving a time interval of 5 seconds or more after discharging the polymer solution on the stage until discharging the polymer solution from above to the same point. Thus, the gel layer can be layered in the upward direction.
(5) By mold-molding the mold in an environment where the temperature distribution inside the thermostatic chamber is constant, the gelation time of the discharged polymer solution is constant regardless of the height of the stack, and the dimensional accuracy of the formed mold is improved. improves.

  DESCRIPTION OF SYMBOLS 1 ... Laminate shaping apparatus, 10 ... Droplet discharge mechanism, 12 ... Droplet discharge means, 20 ... Stage, 22 ... Heating mechanism (heater), 30 ... Drive part, 32 ... Discharge solution cooling means, 35 ... dispenser, 40 ... mold, 42 ... layer, 50 ... constant temperature bath.

Special table 2013-542728 gazette Patent No. 5019851 Patent No. 5264103

Doo Sung Lee, Macromol. Rapid Commun. 2001, 22, 587.

Claims (6)

Using a polymer solution having a sol-gel transition temperature that is solated at a temperature lower than the sol-gel transition temperature and gelled at a temperature higher than the sol-gel transition temperature, a predetermined contact angle at which the polymer solution does not wet and spread On a stage made of a base material to be formed, the stage or atmosphere is formed in a temperature environment higher than the sol-gel transition temperature.
A step of discharging a polymer solution held at a temperature lower than the sol-gel transition temperature onto the stage by a droplet discharge mechanism;
Maintaining the polymer solution discharged to the stage at a temperature higher than the sol-gel transition temperature and gelling;
Relatively moving the droplet discharge mechanism and the stage to form a gel layer on the stage in the shape of the locus of relative movement;
And a step of further discharging a polymer solution onto the gel layer by the droplet discharge mechanism, wherein the gel is layered and formed. In the manufacturing method of the casting_mold | template described in Claim 1,
A method for producing a mold, wherein the viscosity of the polymer solution discharged in the step of discharging the polymer solution to the stage is less than 500 mPa · s. In the manufacturing method of the casting_mold | template described in Claim 1,
A method for producing a mold, wherein the surface of the substrate is made of plastic or glass subjected to a liquid repellent treatment, a metal subjected to a liquid repellent treatment, and a combination thereof. In the manufacturing method of the casting_mold | template described in Claim 1,
In the step of forming the gel layer having the shape of the locus of relative movement on the stage, the time interval from the time when the polymer solution is discharged onto the stage to the time when the polymer solution is discharged from above onto the same point is 5 seconds. A method for producing a mold characterized by the above. In the manufacturing method of the casting_mold | template described in Claim 1,
Each of the above steps is performed in a thermostatic chamber. In the manufacturing method of the casting_mold | template described in Claim 1,
The predetermined contact angle is 90 ° or more.

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