JP2662934B2 - Stereolithography simple mold and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simplified type used for producing a prototype and the like and a method for manufacturing the same.

[0002] The stereolithography referred to here includes, in addition to stereolithography in a narrow sense, an object having a predetermined shape obtained by irradiating light (visible light, laser light, ultraviolet light, etc.) with a resin to solidify the resin. Includes modeling systems that use a suitable fluid medium that cures in response to reactive energy, such as electron beams, x-rays, high energy particle beams, and the like. Furthermore, the present invention also includes a shaping system that uses a technique of accurately positioning and projecting a small unit of the reactive chemical substance onto a fluid medium which hardens in response to the reactive chemical substance. It also includes modeling systems that use so-called lithographic techniques to project such energy and materials through a mask.

[0003]

2. Description of the Related Art A method of stereolithography of a product master model is known (Japanese Patent Application Laid-Open No. 56-144478, Japanese Patent Publication No. 2-48).
422). It is also known to use this model to create a mold (such as a simplified mold) by a resin molding method or the like.

[0004] A conventional mold making process by a resin molding method will be described with reference to FIG. FIG. 2A shows a state in which the model 101 and the parting jig 103 are being combined, and FIG. 2B shows a state in which the two are combined.
This model 101 is formed by stereolithography. The parting jig 103 is formed by machining, hand finishing, or the like.

Next, as shown in FIGS. 2C and 2D, the periphery of the fitted model 101 and the parting jig 103 is surrounded by a wax 105 (an acrylic plate or the like).
The cavity mold 107 is formed and solidified on the parting surface 111 and the parting surface 131 of the parting jig 103 by a resin molding method (epoxy resin added with aluminum powder). Next, as shown in FIG. 2 (E), the waist is removed, and the part is turned upside down, and the parting jig 103 is removed. After that, a drill hole (a dowel hole 175) for alignment of the core mold and the cavity mold is formed on the parting surface 17 of the cavity mold 107.
Open on top of 1.

Next, as shown in FIGS. F and G,
An arm 105 is set around the combination of the model 101 and the cavity mold 107, and the inner surface 11 of the model 101 is
5. After applying a release agent to the parting surface 111, a core mold 108 is formed and solidified by a resin molding method. Then, the core mold 108 and the cavity mold 107 are separated from each other, the model 101 is removed, and as shown in FIG. The mold is completed.

[0007]

In the above-described conventional mold making process, only the master model is optically formed. The mold has been manufactured through a process of transferring a model (in addition to the resin molding described above, plaster casting, thermal spray deposit, etc.). This is because conventionally, since the photocurable resin was not so hard (strong), it was thought that the mold itself could not be produced by the photolithography process.

[0008] As described above, the conventional simple type is made through a transfer process, and thus has the following problems. A master model was needed and it took time to create it. When transferring from the master model to make a mold, the dimensional and shape accuracy became worse with the transfer.

[0009] It took time to transfer the master model. The transfer of the master model required the special skills of a skilled person. The special skills include, for example, determination of a parting surface, creation of a parting jig, temperature control of resin, mixing and defoaming. The mold making process was long due to master model creation and transfer work.

The present invention can be manufactured with low man-hours and low cost,
It is an object of the present invention to provide a simple type with a short delivery time and high accuracy, and a method for manufacturing the same.

[0011]

Means for Solving the Problems The present inventor has developed a new technical basic concept that breaks the conventional technical common sense, that is, the idea that "a master model can be created by an optical molding process, not a mold itself". And completed the present invention.

The simplified stereolithographic mold of the present invention comprises a photocured photocurable resin, and inorganic material-reinforced particles and whiskers dispersed and mixed in the photocurable resin. Has an average particle size of 3 to 70 μm,
The compounding ratio is 5 to 65% by volume, and the whisker has a diameter of 0.3 to 1 μm, a length of 10 to 70 μm, an aspect ratio of 10 to 100, and a compounding ratio of 5 to 30% by volume.
Wherein the total blending ratio of the inorganic material-reinforced particles and the whiskers is 10 to 70% by volume. Here, the particles mainly contribute to the improvement of the thermal conductivity and the surface hardness, and the whiskers mainly contribute to the improvement of the surface hardness and the flexural modulus.

[0013]

The stereolithography simple mold of the present invention differs from the absolute common sense in the conventional stereolithography process, and the mold itself is basically made of a photocurable resin. Therefore, a simplified model can be directly (without a model) created by a stereolithography process that can be linked to a so-called CAD / CAM system. Therefore, the conventional technology (model creation →
(Transfer) can solve the above-mentioned problems of the mold.

In the stereolithography simplified type of the present invention, it is desirable that the material forming the simplified type has a Rockwell surface hardness of M-30 or more and a flexural modulus of 400 kg / mm ² or more. With such mechanical properties, it is sufficient for a simplified type that can receive relatively low load. Examples of such simple molds include an aluminum plate press mold, a plastic injection mold, a foam mold, and a RIM (Reaction I).
njection Molding) molding molds and vacuum casting molds. Further, in order to increase the durability and molding accuracy of the mold, the hardness is preferably M-50 or more, and the flexural modulus is preferably 600 kg / mm ² or more.

In the stereolithography simplified type of the present invention, it is desirable that the material constituting the simplified type has a thermal conductivity of 0.3 kcal / m · Hr · ° C. or more. In particular, in a mold such as an injection molding mold that needs to release heat from the inside to the outside, it is desirable to provide such a thermal conductivity characteristic to a simple mold.
Further, in order to increase the molding speed, the thermal conductivity is set to 0.1.
It is preferably at least 4 Kcal / m · Hr · ° C.

[0016] The reinforcing particles dispersed formulated into easy easy type of the present invention are inorganic material particles, the average particle size of the particles is 3
And the compounding ratio of the particles is 5 to 70% by volume.
It may be.

[0017]

The reason why the average particle size of the reinforcing particles is preferably 3 to 70 μm will be described. When the average particle size is less than 3 μm, the viscosity of the uncured photocurable resin containing the reinforcing particles becomes too high, so that shaping (layer formation) becomes difficult.
When the average particle size exceeds 70 μm, irradiation energy (light or the like) for curing is scattered, and the accuracy of modeling is reduced.

The average particle size of the reinforcing particles is more preferably from 10 to 60 μm, and most preferably from 15 to 50 μm. The reason is that, in that range, the balance between the formability and the accuracy is good.

The compounding ratio of the reinforcing particles is 5 to 70% by volume.
The reason why (based on the total volume of the photocurable resin and the reinforcing particles) is preferable will be described. If it is less than 5%, the flexural modulus will not reach 400 kg / mm ² and the thermal conductivity will be low. 70%
If it exceeds 3, the viscosity of the compound in the uncured stage becomes too high, so that molding becomes difficult. The viscosity of the compound (resin + particles) after the uncured compounding is 5,000 to 100,000 CP.
S is preferable for production.

The mixing ratio of the reinforcing particles is more preferably from 20 to 65%, and most preferably from 30 to 60%. This is because, in that range, the balance between mechanical properties and formability is good.

Other properties of the reinforcing particles in the stereolithography simplified type of the present invention will be described. It is better to have translucency. However, it is not a required condition. The energy beam for curing is
This is because the particles also wrap around to the back side of the particles due to reflection or the like. The shape of the particles is preferably closer to a smooth sphere. This is because the fluidity of the blend is improved.

[0023]

Examples of the inorganic reinforcing particles include glass beads, talc particles, and SiO ₂ particles.

In the stereolithography simplified type of the present invention, a diameter of 0.3 to 1 μm and a length of 10 to 70 μm together with the reinforcing particles are used.
m, whiskers having an aspect ratio of 10 to 100 may be dispersed and blended in the photocurable resin in an amount of 5 to 30% by volume.

[0026]

The whiskers used in the present invention are preferably made of at least one of aluminum borate compounds, magnesium hydroxide sulfate compounds, aluminum oxide, titanium oxide compounds and silicon oxide compounds. Further, preferably, an aluminum borate-based compound,
It is a magnesium hydroxide-based compound, an aluminum oxide and a titanium oxide-based compound.

The diameter (or width) of the whiskers used in the present invention is preferably in the range of 0.3 μm to 1 μm, more preferably 0.3 μm to 0.7 μm. Also,
The length is preferably in the range of 10 μm to 70 μm, more preferably 20 μm to 50 μm. The aspect ratio is preferably in the range of 10 to 100, and more preferably 20 to 70.

When the aspect ratio of the whisker used in the present invention is smaller than 10, the effect of the present invention when the whisker is added, that is, the special effect of improving the mechanical strength is not obtained, and the viscosity of the resin is unnecessarily increased. It is only unfavorable because it only rises. On the other hand, if the aspect ratio of the whisker increases, the effect of improving the mechanical strength and decreasing the volume shrinkage is expected, but if the aspect ratio exceeds 100, the viscosity of the resin becomes too high, or the resin becomes too high. Not only the fluid elasticity becomes high and the shaping operation becomes difficult, but also the length of the whisker becomes longer and the side precision of the shaped object is reduced, so the size of the aspect ratio is limited, and the aspect ratio is preferably 100 or less,
More preferably, it is 70 or less.

The mixing ratio of the whiskers to the liquid photocurable resin used in the present invention is preferably 5 to 30% by volume. Further, it is preferably 7 to 20% by volume. When the mixing ratio of the whisker is less than 5% by volume, the effect of the present invention is not sufficiently exhibited, while the mixing ratio is
If it exceeds 30% by volume, the viscosity of the resin composition for optical three-dimensional modeling becomes too high, which causes not only difficulty in use but also impairs the penetration of light and involves difficulty in modeling.

When using inorganic material particles and whiskers, the compounding ratio of the reinforcing particles is 30 to 50%, the compounding ratio of the whiskers is 10 to 20%, and the total compounding ratio of both is 40 to 40%.
More preferably, it is 60%. This is because, in this range, the balance between mechanical properties and formability is good.

The liquid photocurable resin used in the present invention may be any of a polymerizable vinyl compound and an epoxy compound, and any monomer or oligomer of a monofunctional compound or a polyfunctional compound is used. These monofunctional compounds and polyfunctional compounds are not particularly limited, and typical examples of the liquid photocurable resin are given below.

[Polymerizable vinyl compound] 1) Monofunctional compounds include isobornyl acrylate, isobornyl methacrylate, zinclopentenyl acrylate, bornyl acrylate, bornyl methacrylate, 2-hydroxyethyl acrylate, and 2-hydroxyethyl acrylate. Examples include hydroxypropyl acrylate, propylene glycol acrylate, vinyl pyrrolidone, acrylamide, vinyl acetate, styrene and the like.

2) Polyfunctional compounds include trimethylolpropane triacrylate, EO-modified trimethylolpropane triacrylate, ethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, 1,4-
Butanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, dicyclopentenyl diacrylate, polyester diacrylate, diallyl phthalate and the like.

One or more of such monofunctional compounds and / or polyfunctional compounds can be used alone or in the form of a mixture.

As the polymerization initiator of the vinyl compound used in the present invention, a photopolymerization initiator and a thermal polymerization initiator are used. As the photopolymerization initiator, 2,2-dimethoxy-2-phenylacetophenone is used. , 1-hydroxycyclohexylphenyl ketone, acetophenone, benzophenone, xanthone, fluorenone, bezaldehyde, fluorene, anthrequinone, triphenylamine, carbazole, 3-methylacetophenone, Michler's ketone, and the like. However, these initiators can be used alone or in combination of two or more. If necessary, a sensitizer such as an amine compound can be used in combination.

Typical thermal polymerization initiators include benzoyl peroxide, t-butylperoxybenzoate, dicumyl peroxide, diisopropylperoxydicarbonate, t-butyl peroxide, azobisisobutyronitrile and the like. Can be mentioned. The amount of the polymerization initiator or the thermal polymerization initiator used in the present invention is preferably 0.1 to 0.1 parts per vinyl compound.
1 to 10% by weight.

[Epoxy Compounds] Typical examples thereof include hydrogenated bisphenol A diglycidyl ether, 3,4-epoxycyclohexylmethyl-3,4-
Epoxycyclohexanecarboxylate, 2- (3,
4-epoxycyclohexyl-5,5-spiro-3,4
-Epoxy) cyclohexane-m-dioxane, bis (3,4-epoxycyclohexylmethyl) adipate and the like. When these epoxy compounds are used, an energy-active cation initiator such as triphenylzulphonium hexafluoroantimonade is used.

The liquid photocurable resin used in the present invention may contain, if necessary, a leveling agent, a surfactant, an organic polymer compound, an organic plasticizer, a filler such as organic beads other than those described above, and a filler other than the above. And inorganic fillers such as glass beads. As the resin composition of the present invention, the vinyl-based compound and the epoxy-based compound may be used alone or in combination of two or more, and if necessary, other components may be blended. The mixing method is not particularly limited.

The reinforcing particles or whiskers of the stereolithography type according to the present invention are preferably surface-treated with at least one silane coupling agent of aminosilane, epoxysilane and acrylic silane. When reinforced particles or whiskers used in such a silane coupling agent are used, a preferable simple type having particularly excellent mechanical strength can be obtained.

It is preferable that the type of the silane coupling agent is appropriately selected depending on the liquid photocurable resin to be used. For example, when a vinyl-based unsaturated compound is used as the liquid photocurable resin, an acrylic silane-based silane coupling agent is most preferable. When an epoxy-based compound is used as the liquid photocurable resin, it is most effective to use an epoxysilane-based silane coupling agent.

In the method of manufacturing a stereolithography simplified mold according to the present invention, a step of constructing the shape data of the mold, a step of arranging the uncured photocurable resin in a stepwise manner, and a step of selecting using the shape data of the mold. Selectively exposing the photocurable resin layer at the site where the photocurable resin layer is located.

The above type data construction step is performed by a so-called CA
It is preferably performed using a D system. As a method of hierarchically arranging uncured photocurable resin (including a material in which reinforcing particles are dispersed and blended), a method of thinly pouring a flowable photocurable resin (JP-A-3-227222, JP-A-2-212131) And a method of stacking a sheet-like photocurable resin. In addition, Japanese Patent Application No. 5-25620 pertaining to the same applicant.
5. The method described in Japanese Patent Application No. 6-5519 can also be employed.

As a method for selectively exposing the photocurable resin layer, a laser scanning method or a mask method can be employed. The thickness of the photocurable resin layer at the time of exposure is not particularly limited, but can be selected in the range of about 75 μm to 0.5 mm in consideration of the shape accuracy and productivity of the mold.

[0045]

EXAMPLES Example 1 (with reinforcing particles and whiskers) Examples of the present invention will be described below. FIG. 1 is a view showing a structure of a simplified optical molding type for injection molding according to one embodiment of the present invention. (A) is a plan view of a core mold, and (B) is a cross-sectional view of a core cavity mold.

This simple mold is a mold for plastic injection molding. A core portion 11 is provided at the center of the lower surface of the core mold 1. A cavity 31 is provided at the center of the upper surface of the cavity mold 3. The gates 13 and 3 are provided on the core 11 and the cavity 31 from the right side of the figure.
The plastic is injected from the gates 13 and 33. Pin holes 15 and 35 for positioning are formed in squares of the core mold 1 and the cavity mold 3. Positioning pins (steel, not shown) are passed through the holes 15 and 35.

Next, a description will be given of a manufacturing process of the optical molding simplified type shown in FIG. (1) Design: The mold was designed using a three-dimensional CAD system. The CAD system used is capable of creating STL data to be input to the optical forming apparatus for the designed three-dimensional mold.

(2) Mixing of photo-curing resin and reinforcing particles: (2.1) Example of synthesizing photo-curing resin (Synthesis of urethane acrylate oligomer) After stirring, 5 liter of a cooling tube and a dropping funnel with a side tube were provided. Trimerized isophorone diisocyanate in a three-necked flask
1023 g of PDI terpolymer (manufactured by Sumitomo Bayer; Dismodule Z-4372) and 0.076 g of dibutyltin laurate are charged, and the internal temperature is adjusted to 65 ° C. in an oil bath.

420.1 g of polyneopentylene adipate (Adeka New Ace Y9-10, manufactured by Asahi Denka Co., Ltd.) is charged into a dropping funnel with a side tube which is kept at 50 ° C. in advance. The operation of reducing the pressure in the entire system and returning to normal pressure with nitrogen gas is repeated to perform degassing and nitrogen replacement. Make the whole system normal pressure,
In a nitrogen atmosphere, while maintaining the temperature of the contents of the flask at 65 ° C. and stirring the contents, polyneopenthylene adipate is added dropwise from the dropping funnel over 1 hour. After the addition, the content is maintained at 65 ° C. for another hour, and the reaction is continued with stirring.

After cooling the temperature of the contents of the flask to 50 ° C., 2-hydroxyethyl acrylate 2 was added to the dropping funnel.
A liquid obtained by uniformly dissolving and mixing 0.90 g of methylhydroquinone in 54.5 g was charged, and the temperature of the contents of the flask was 55 ° C.
Drop quickly within the range that does not exceed
Continue the reaction. The resulting urethane acrylate oligomer is taken out of the flask while the contents are warm. As a result of IR and elemental analysis, it was confirmed that the obtained urethane acrylate oligomer had the following structural formula.

[0051]

Embedded image

Here, n has an average value of 4, and R represents the following groups.

[0053]

Embedded image

(2.2) Preparation of Optical Molding Composition In a 5-liter three-necked flask equipped with a stirrer, a cooling tube and a dropping funnel equipped with a side tube, 1320 g of urethane acrylate synthesized in the synthesis example, polyethylene glycol 200 diacrylate ( Sartmar SR259) 1
080 g and ethoxy-modified trimethylolpropane triacrylate (manufactured by Somar; Sartomer SR454)
480 g was charged and the atmosphere was replaced by degassing under reduced pressure. 5 contents
The mixture was heated to 0 ° C. and stirred and mixed for about 1 hour.

In an environment where ultraviolet rays are cut off, 120 g of 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651 manufactured by Ciba Kaigie Co., Ltd.) is added, and the mixture is stirred until completely dissolved. 14 g of Superdyne V201 (manufactured by Takemoto Yushi Co., Ltd.) as a leveling agent and aluminum borate whisker (Arbolex Y) treated with an acrylic silane coupling agent were added to the obtained resin composition.
S-4; Shikoku Chemical Industry Co., Ltd.) (1600 g) was added, and the mixture was stirred at room temperature for 5 hours and defoamed. Glass beads 5 having an average particle size of 30 μm treated with an acrylic silane coupling agent
333 g (GP-731C manufactured by Toshiba Barotini) was added, and the mixture was further degassed by stirring at room temperature. The resulting clay of the stereolithography resin composition had a viscosity of 40,000 cps at 25 ° C.

(3) Lamination and Selective Exposure: Photocurable resin lamination and selective exposure were performed by the method of Japanese Patent Application No. 6-5519 filed by the present applicant (coating → laser scanning exposure) to form a mold. Various conditions at this time were as follows. Photocurable resin layer thickness: 0.15 mm Exposure conditions: argon laser (wavelength 368 μm), laser power 350 mW, scanning speed 6 m / sec

(4) Secondary curing: After the formed mold was washed with isopropyl alcohol, it was irradiated with ultraviolet rays (metal halide lamp, 4 KW) for 10 minutes.

(5) Mechanical Property Check: A test piece was taken from a part of the mold to check the mechanical properties of the mold. The results were as follows. Rockwell surface hardness: M-60 Flexural modulus: 692 kg / mm ² Thermal conductivity: 0.43 kcal / m · Hr · ° C

(6) Machining: Extrusion pins, gate holes, etc. were machined.

(7) Die set assembling: An optical molding simple mold was assembled into a die set and set in an injection molding machine.

(8) Injection molding: AB using a stereolithography simple mold
50 S resin products were injection molded. The molding condition is temperature 1
The temperature was 70 ° C. and the pressure was 95 kgf / cm ² . At this point, no damage or deformation of the mold was observed, and it was judged that molding of about 100 pieces was possible. Also, there were no burrs on the molded product. The dimensional accuracy was also about ± 0.1 mm with respect to the figure dimension of 30 mm. Overall, the simplified version was satisfactory. Each of the above steps could be performed sufficiently within one week.

[0062]

[0063]

[0064]

[0065]

In addition to the mold materials described in the above embodiments, the materials described in Japanese Patent Application Nos. Hei 5-196669 and Hei 5-196692 of the same applicant as the present application are also used for the simplified mold making of the present invention. Used for

[0067]

As is clear from the above description, the stereolithography simplified type of the present invention and the manufacturing method thereof exhibit the following effects. Since there is no need to create a master model or to transfer and create a mold, a mold with low man-hours and low cost can be obtained. Also, the delivery date is short. Since it can be manufactured without a transfer process, the dimensional and shape accuracy of the mold is good. The durability and productivity as a mold can be satisfied as a simple mold level.

[Brief description of the drawings]

FIG. 1 is a view showing a structure of a simplified optical molding type of injection molding according to an embodiment of the present invention.

FIG. 2 is a view showing a conventional model transfer type simplified manufacturing process.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Core mold 13, 33 Gate 3 Cavity mold 15, 33 Positioning pin hole 11 Core part 31 Cavity part

Claims (3)

(57) [Claims] 1. A photocurable resin comprising: a photocurable resin; and inorganic material-reinforced particles and whiskers dispersed and mixed in the photocurable resin, wherein the inorganic material-reinforced particles have an average particle size of 3 to 3. 70 μm, the compounding ratio is 5 to 65% by volume, and the whisker has a diameter of 0.3 to 1 μm, a length of 10 to 70 μm, and an aspect ratio of 10 to 100,
The stereolithography simple type, wherein the compounding ratio is 5 to 30% by volume, and the total compounding ratio of the inorganic material-reinforced particles and the whiskers is 10 to 70% by volume. Wherein the reinforcing particles or whiskers, aminosilane, epoxysilane, claim 1 stereolithography simplified according those which are surface treated with at least one or more kinds of silane coupling agents of acrylic silanes. 3. A step of constructing the shape data of the mold, a step of arranging the uncured photocurable resin in a hierarchical manner, and selecting the photocurable resin layer at the site selected using the shape data of the mold. 3. The method of manufacturing a stereolithography simple type according to claim 1, further comprising: