KR20150140980A - Insulating mold for injection molding - Google Patents

Abstract

The present invention relates to a heat-insulating mold for injection molding, and more particularly, to a mold for injection molding in which an inner portion of a core is filled with a molten resin to form an injection-molded article, wherein a heat insulating layer is formed on one side or both sides of the mold, The present invention relates to a heat-insulating mold for injection molding capable of precisely molding a fine pattern on a product by improving moldability and moldability of the mold even at a low mold temperature by providing a mold for injection molding laminated with a high heat- will be.

Description

[0001] INSULATING MOLD FOR INJECTION MOLDING [0002]

The present invention relates to a heat-insulating mold for injection molding, and more particularly, to a mold for injection molding in which a high heat-resistant polymer laminated with a fine pattern is formed, thereby improving moldability and moldability even at a low mold temperature, To a heat-insulating mold for injection molding capable of precisely molding a fine pattern.

In recent years, as the thickness of a light guide plate (LGP) used in a backlight unit (BLU) for a liquid crystal display has become thinner, a limit to a conventionally used injection molding metal has been a problem.

The light guide plate functions to uniformly illuminate the backlight unit and functions to uniformly disperse the light emitted from the lamp in the entire area of the screen.

Generally, the light guide plate is manufactured by injection molding, in particular, injection compression molding, and an optical pattern must be formed on the surface. Polymethyl methacrylate (PMMA) is mainly used as a material of the light guide plate, but polycarbonate (PC) may be used in some cases.

The light guide plate is classified into a planar light guide plate having a thicker light entrance portion, a thin light guide plate having a thin light guide portion and a light guide plate having the same thickness as the whole light guide plate. In recent years, the thickness of a backlight unit has become thinner as a light source has been miniaturized. It needs to be minimized.

However, as shown in FIG. 1, since the surface layer 10 is instantaneously formed and solidified to a thickness of about 10 to 100 μm due to a thermal shock due to a high thermal conductivity of the mold on the surface of the injection molded article, There is a problem that it is difficult to secure the thickness of the core layer 20 required in the adiabatic system by the surface layer.

Therefore, there is a need for a technique for more precisely manufacturing a thin shaped article, in particular, a sample having a fine pattern formed on its surface.

The above products may include all kinds of thin type articles used in ordinary injection fields such as thin films, various sensors such as temperature sensors, and optical articles such as lenses for mobile phones and cameras, no.

Techniques for improving the fillability and moldability in the injection molding process include mold technology and molding process technology. There are techniques such as the use of a hot runner and the increase of the diameter of a gate in the mold technology. However, there is a problem that it is difficult to mold a thin plate or a fine pattern due to limitations on material and mold processing.

Molding process technology is a technology that improves filling property and moldability by changing process conditions without modification of mold. For this purpose, it is important to reduce the heat flux between the injection mold and the mold.

The heat flux means the amount of heat energy transferred through the unit area per unit time, and can be expressed by the following equation (1).

q = h *? T (1)

Here, q (W / m ² ) is the heat flux, h (W / Km ² ) is the heat transfer coefficient, and ΔT (K) is the temperature difference.

Increasing the mold temperature in the molding fixation technique reduces the temperature difference between the article and the mold according to equation (1) to reduce the heat flux. However, when the mold temperature is increased, the final cooling temperature of the product is also increased, and there is a problem that a trace of an eject pin is generated when the mold is demoulded.

In order to improve the moldability, Korean Patent Laid-Open Publication No. 10-2012-0086518 discloses a molding apparatus using a thin film heater. However, a plurality of films that generate heat by power supplied from an external power supply unit separately There is a limitation in that a heater is necessarily included.

It is an object of the present invention to provide a method of manufacturing a laminate by laminating a heat insulating layer having a fine pattern formed thereon without a separate heater device to the inner surface of the mold to reduce the heat transfer coefficient between the article and the mold, And to provide a heat-insulating mold for injection molding.

In order to achieve the above object, a mold for injection molding according to the present invention is a mold for injection molding in which an inside of a core is filled with a molten resin to form an injection mold, wherein a heat insulating layer is formed on one side or both sides of the mold .

The heat insulating layer of the injection mold according to the present invention preferably has a predetermined fine pattern formed on its surface.

Further, it is preferable that a heat insulating layer having a predetermined fine pattern is formed on one side of the mold for injection molding according to the present invention, and a non-patterned heat insulating layer is formed on the other side.

It is preferable that the heat insulating layer of the mold for injection molding according to the present invention is a laminate layer formed by laminating.

Further, it is preferable that the mold for injection molding according to the present invention further includes an adhesive layer positioned between the heat insulating layer and the mold.

Further, the heat insulating layer of the mold for injection molding according to the present invention is preferably made of a high heat resistant polymer resin.

The high heat-resistant polymer resin of the mold for injection molding according to the present invention is preferably polyimide.

In addition, it is preferable that the injection mold formed by the injection mold according to the present invention is formed by injection compression molding.

The molded article formed by the injection molding die according to the present invention is preferably a light guide plate, a thin film, a sensor, or an optical product.

According to the present invention, it is possible to manufacture a thin shaped article by reducing the heat flux between the article and the mold to minimize the generation of a skin layer of the article due to thermal shock.

Further, since the laminate layer itself has a fine pattern formed thereon, it is possible to form a finished product requiring a fine pattern on the surface like a light guide plate.

Further, it is possible to perform injection molding at a low mold temperature, thereby reducing the residual stress of the injection molding.

In addition, the present invention can be applied to manufacture of all kinds of thin products such as light guides, thin films, various sensors such as temperature sensors, and optical products such as lenses for mobile phones and cameras.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a cross-sectional view of an injection-molded article having a surface layer formed thereon. FIG.
2A to 2C are cross-sectional views of a heat-insulating mold for injection molding according to a first embodiment of the present invention.
3A and 3B are cross-sectional views of a heat-insulating mold for injection molding according to a second embodiment of the present invention.
4A to 4P are a photograph of a surface and an enlarged view of a sample having nanopatterns formed using a general mold as a comparative example.
5A to 5P are photographs of a surface and an enlarged view of a sample having nanopatterns formed using the heat-insulating mold according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to facilitate a person skilled in the art to easily carry out the technical idea of the present invention. . In the drawings, the same reference numerals are used to designate the same or similar components throughout the drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The mold for injection molding is usually made of a material having excellent thermal conductivity, such as general steel or aluminum alloy, or coated with such a material. Therefore, after the molten resin is filled, the mold is rapidly radiated to the surface of the mold during cooling, thereby forming a solidified layer on the surface.

When a solidified layer is formed on the surface of the article to be printed, the transferability and moldability for transferring the pattern are lowered, and it is impossible to obtain a thin article or an article to form a desired level of pattern.

A mold according to an embodiment of the present invention aims at minimizing a heat flux between an injection mold and a mold in a mold for injection molding in which an injection molding is formed by filling a molten resin into a core.

By minimizing the heat flux, it is possible to delay the formation of the solidified layer to the maximum extent, so that it is easy to produce thin-walled articles, and problems such as defective transfer can be solved.

For this purpose, it is required to reduce the temperature difference between the molten resin and the mold or to reduce the heat transfer coefficient. The present invention aims to reduce the heat transfer coefficient as described above.

Since the heat transfer coefficient is related to the interface characteristics between the molten resin and the mold, the heat flux can be minimized by forming a heat insulating layer on one side or both sides of the mold by using an insulating material having a low thermal conductivity.

Considering the high-temperature environment of the mold, the material of the heat insulating layer can be a high heat-resistant polymer having excellent thermal characteristics, and it is preferable to use a Teflon material or an aromatic polymer, especially a polyimide resin.

Polyimide is a polymer containing imide groups in repeating units. It has strong chemical bond due to imide group, strong structure, resonance stabilization, and normal angular structure, and exhibits high softening point and glass transition temperature , Exhibits mechanical properties even at high temperatures, and has excellent thermal stability, such as resistance to thermal decomposition.

2A to 2C are cross-sectional views of a heat-insulating mold for injection molding according to a first embodiment of the present invention.

A mold according to a first embodiment of the present invention relates to a mold for injection molding in which molten resin is filled in a core to form an injection mold, and a heat insulating layer is formed on one side or both sides of the mold.

The injection mold has a first mold 100 having a predetermined area and a predetermined thickness and a second mold 200 coupled to the first mold 100 to form a cavity or core (not shown) ).

When the first mold 100 and the second mold 200 are coupled to each other, a core or cavity, which is a space between the first mold 100 and the second mold 200, is formed, and the molten injection resin material to be injected is injected into the core.

In the present invention, the molten resin is injected into the core through the inlet port 110 formed in the first mold 100, but the method of injecting the raw resin in the core is not limited thereto.

In the injection mold, FIG. 2A shows a heat insulating layer formed on the inner surface of the first mold facing the core corresponding to the mold, FIG. 2B shows the heat insulating layer on the inner surface facing the core of the second mold, And Fig. 2C shows a heat insulating layer formed on both sides of the first mold and the second mold.

The heat insulating layer according to the embodiment of the present invention is characterized in that a predetermined fine pattern is implemented on the surface.

As described above, the heat insulating layer formed on the inner surface of the mold minimizes the heat flux between the mold and the molten resin, thereby improving the filling property and the moldability to enable production of thin film articles. In the present invention, fine patterns are formed on the heat insulating layer itself , And an article of manufacture in which a nano-sized pattern is formed can be easily formed.

A heat insulating layer may be formed on one side of the mold composed of the first mold 100 and the second mold 200 or a heat insulating layer may be formed on both sides according to a desired pattern formation position of the article to be printed.

That is, when a predetermined fine pattern is to be formed on one side of the injection mold, when a molten resin is injected into a heat-insulating mold having a heat insulating layer formed on one side of the mold and a heat insulating layer is formed on both sides of the mold The molten resin is injected into the adiabatic mold.

There is no limitation on the shape of such a fine pattern, and various sizes can be applied in nanometers to micrometers depending on the size of the unit pattern and the characteristics of the product.

3A and 3B are cross-sectional views of a heat-insulating mold for injection molding according to a second embodiment of the present invention.

A mold according to a second embodiment of the present invention relates to a mold for injection molding in which molten resin is filled into a core to form an injection mold, and a heat insulating layer 300 having a predetermined fine pattern is formed on one side of the mold And a non-pattern insulation layer 400 is formed on the other side of the mold.

Unlike the heat insulating layer 300 in which fine patterns are formed on the surface, the non-pattern insulating layer 400 includes both a heat insulating layer on which no intentional pattern is formed or a heat insulating layer on which no pattern forming treatment is performed.

The heat insulating mold 300 in which the heat insulating layer 300 having the fine pattern formed on one side of the mold and the heat insulating layer is not formed on the other side is used to prevent the formation of the solidification layer or the surface layer on the surface of the injection mold corresponding to the other side of the mold during injection However, since the mold according to the second embodiment of the present invention is formed with the non-pattern thermal insulation layer 400 on which the pattern is not formed on the other side of the metal mold, it is possible to produce a thinner film having a thinner thickness.

The heat insulating layer may be a coating layer formed by coating, but in the present invention, it is preferably a laminate layer formed by laminating.

The laminate layer refers to a laminate film made of a resin material such as polyimide or the like. Unlike a coating layer on which a pattern is not easily formed on a surface, the laminate layer has an advantage of being easily patterned.

Such a laminate layer is attached to the inner surface of the mold and has adhesiveness by itself when injected, but it is possible to further improve the bonding strength between the mold and the laminate layer by forming an adhesive layer between the heat insulating layer and the mold using an adhesive material desirable.

A laminate film made of a high heat resistant polymer resin such as polyimide serves as a heat insulating layer that minimizes heat transfer between the mold and the molten resin and a pattern is formed on the film surface itself, A pattern corresponding to the pattern formed on the substrate is formed.

The heat insulating mold according to the present invention may be an injection molding, especially an injection compression molding mold.

Injection compression molding is an extension of traditional injection molding. Unlike filling a predetermined amount of molten resin into a mold space and then pressurizing the molten resin through a gate or runner, the molding force or the core in the mold is used The residual stress of the molded article is relaxed and a uniform molded article can be obtained.

In particular, since the heat insulating mold according to the present invention includes a heat insulating layer having a fine pattern formed on one side or both sides of a mold, it is easy to apply to a light guide plate in which a fine pattern is essentially formed on the surface, A thin light guide plate can be manufactured.

In addition to the light guide plate, there is an effect that it is possible to precisely manufacture all kinds of thin type articles to be applied in ordinary injection fields such as various sensors such as thin films, temperature sensors, and optical products such as lenses for mobile phones and cameras.

In order to manufacture the heat-insulating mold according to the present invention, it is essential to form a laminate layer having a pattern on the inner surface of the mold.

Specifically, it is possible to attach a laminate layer in which a fine pattern is implemented to a metal mold or to attach a laminate layer to a metal mold to form a fine pattern.

Such a laminate layer is formed on the inner side of the mold by laminating a film made of a high heat-resistant polymer such as polyimide or the like, and it is also possible to use an adhesive component as needed during the laminating process.

When the mold having the heat insulating layer on which the fine pattern is formed is completed, the molten resin is injected into the mold cavity and cured to produce an injection mold having the same pattern as the fine pattern embodied in the heat insulating layer.

Then, the mold is separated, and the injection product is separated and extracted from the mold through the eject pin.

Hereinafter, the heat-insulating mold for injection molding according to the present invention will be described in more detail with reference to embodiments of the present invention. However, these examples are for illustrative purposes only, and the scope of the present invention is not limited to these examples.

In order to confirm the moldability and filling property of the heat-insulating mold for injection molding according to the present invention, a conventional article having fine patterns formed using a conventional heat-insulating mold is manufactured, and a heat- After making the entries, the formed fine patterns were compared.

A method of manufacturing a finished article having a fine pattern using a conventional heat-insulating mold is well known, and a detailed description thereof will be omitted.

The injection product having fine patterns according to various sizes was injection-finished using a general mold, and then a pattern formed on the surface was observed.

4A to 4P are photographs showing the surface of a sample having a nano pattern formed using a general mold as a comparative example.

Specifically, Figs. 4A to 4D show a surface pattern of a nanopattern formed by using a general mold, a nanopattern having a size of about 500 nm, Figs. 4E to 4H, 400 nm, 4I to 4L, and 300 nm, And an enlarged photograph.

On the other hand, a mold formed by laminating a polyimide layer having fine patterns according to the present invention on the inner side of the mold was manufactured through the above-described method, injection products were injection-finished using the mold, and patterns formed on the surface were observed.

5A to 5P are photographs showing the surface of a sample having nanopatterns formed using the heat insulating mold according to the present invention as an example.

Specifically, Figs. 5A to 5D show a nanopattern having a size of about 500 nm, Figs. 5E to 5H about 400 nm, Figs. 5I to 5L about 300 nm, and Figs. 5M to 5P about 200 nm in size, It is a surface photograph and an enlarged photograph of an exhibit.

As shown in the figure, in the case of using a general mold, heat transfer to the mold wall surface is drastically promoted, so that the transferability is degraded and the pattern is distorted. It can be seen that the smaller the pattern size, the worse the degree.

However, in the case of using the heat-insulating mold according to the present invention, it is possible to precisely transfer fine patterns, particularly nano-sized patterns, by minimizing the heat fluxes of the mold and the molten resin, and even when the pattern size is reduced to about 200 nm, .

As described above, an optimal embodiment has been disclosed in the drawings and specification. Although specific terms have been employed herein, they are used for purposes of illustration only and are not intended to limit the scope of the invention as defined in the claims or the claims. Therefore, those skilled in the art will appreciate that various modifications and equivalent embodiments are possible without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

10: surface layer 20: core layer
100: first mold 110: inlet port
200: a second mold 300: a heat insulating layer in which a fine pattern is implemented
400: Non-patterned insulating layer

Claims (9)

1. A mold for injection molding in which an inside of a core is filled with a molten resin to form an injection product,
Wherein a heat insulating layer is formed on one side or both sides of the mold. The method according to claim 1,
Wherein the heat insulating layer is formed with a predetermined fine pattern on the surface thereof. 3. The method of claim 2,
Wherein a heat insulating layer having a predetermined fine pattern is formed on one side of the mold and a non-pattern insulating layer is formed on the other side of the mold. The method according to claim 2 or 3,
Wherein the heat insulating layer is a laminate layer formed by laminating. 5. The method of claim 4,
And an adhesive layer disposed between the heat insulating layer and the mold. ≪ RTI ID = 0.0 > 11. < / RTI > 5. The method of claim 4,
Wherein the heat insulating layer is made of a high heat resistant polymer resin. The method according to claim 6,
Wherein the high heat-resistant polymer resin is polyimide. 5. The method of claim 4,
Wherein the injection mold is formed by injection compression molding. ≪ RTI ID = 0.0 > 18. < / RTI > 9. The method of claim 8,
Wherein the molded article is a light guide plate, a thin film, a sensor, or an optical product.

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