KR102446657B1 - Apparatus containing air tunnel for manufacturing foam sheets - Google Patents

Abstract

The present invention relates to a foam sheet manufacturing apparatus having an airing tunnel in a cooling unit, wherein the foam sheet manufacturing apparatus directly injects a cooling gas in the direction of the outer circumferential surface of the mandrel through the airing tunnel, but the temperature of the extruder and the inside temperature of the cooling unit By maintaining the deviation at a certain level, it is possible to form a skin layer containing non-foaming or micro-foaming cells on the surface of the foaming layer containing uniform foamed cells inside without a separate process, so that the manufacturing process of foam sheets can be simplified. There is an advantage.

Description

Apparatus containing air tunnel for manufacturing foam sheets

The present invention relates to a foam sheet manufacturing apparatus having an airing tunnel in a cooling unit.

Polyester resins with crystallinity such as polyethylene terephthalate (PET) have superior mechanical properties compared to polyethylene-based resins or polypropylene-based resins, and have excellent heat resistance and chemical resistance, and are used in various fields requiring light weight and high physical properties. This is possible. These polyester resins have excellent mechanical and chemical properties, and thus have many applications, for example, conventionally for drinking water containers and medical, food packaging, food containers, sheets, films, and automobile molded products. It has been applied in fields such as

In particular, a foam sheet containing a polyester resin has a foaming layer composed of a resin composition containing a polyester resin, so it is excellent in light weight and strength, so that it can be used as a sheet-shaped molded article as it is, and three-dimensional, such as thermoforming It can be molded into a molded body having a typical shape.

On the other hand, the polyester foam sheet can be manufactured through an extrusion foaming method in which a polyester resin is melt-kneaded into an extruder, a physical foaming agent such as butane is press-injected, and the tip of the extruder pushes the melt-kneaded material from a die to foam, The foam seat prepared in this way has the advantage that the foamed cells are uniform.

However, the foam sheet has an uneven surface due to the foamed cells, or has high fluid permeability such as gas, so that a process of separately forming a non-foamed or small-sized skin layer located on the surface for commercialization is required. there are many

Republic of Korea Registered Utility Model Publication No. 10-0132770

Accordingly, an object of the present invention is to provide an apparatus for manufacturing a foam sheet capable of forming a skin layer including non-foaming or fine foam cells on the surface of the foam layer containing uniform foam cells therein when manufacturing the foam sheet without a separate process is doing

In order to solve the above-mentioned problem,

The present invention in one embodiment,

a hopper that feeds the resin melt;

an extruder having a die for extrusion molding into a foam sheet while discharging the resin melt supplied from the hopper; and

and a cooling unit having a mandrel disposed at the front end of the die.

The cooling unit provides an apparatus for manufacturing a foam sheet including an airing tunnel for injecting cooling gas in the direction of the outer circumferential surface of the mandrel.

In this case, the airing tunnel may have an injection hole for injecting a cooling gas on an inner peripheral surface, and the injection hole may be disposed at a position spaced apart from the outer peripheral surface of the mandrel by 5 to 20 cm.

In addition, in the airing tunnel, 3 to 10 injection holes form an air ring in the inner circumferential direction, and 2 to 10 air rings may be spaced apart from each other in the longitudinal direction of the airing tunnel.

In addition, the air ring tunnel may selectively operate a plurality of air rings to control the internal temperature of the cooling unit.

Specifically, the foam sheet manufacturing apparatus may be controlled to satisfy the following Equation 1:

[Equation 1]

_{┃T cooling} -T extruding ┃ ≥ 200℃

In Equation 1,

The T _cooling represents the temperature of the cooling unit,

The T _extruding indicates the temperature of the extruder.

At this time, the average temperature of the cooling gas dispersed in the airing tunnel of the cooling unit may be -20 to 5 ℃.

In addition, in the airing tunnel, the ratio of the area to which the cooling gas is injected and the area to which the cooling gas is not injected may satisfy 0.05 to 0.5.

In addition, the surface temperature of the mandrel may be -10 to 20 ℃.

Furthermore, the foam sheet manufacturing apparatus may further include a cutter for cutting the foam sheet passing through the cooling unit.

The foam sheet manufacturing apparatus according to the present invention directly sprays the cooling gas in the direction of the outer circumferential surface of the mandrel through the airing tunnel, but maintains the deviation between the temperature of the extruder and the internal temperature of the cooling unit at a certain level, thereby uniformly foaming the inside without a separate process Since it is possible to form a skin layer including non-foaming or fine foamed cells on the surface of the foaming layer including cells, there is an advantage in that the manufacturing process of the foamed sheet can be simplified.

1 is a structural diagram showing the configuration of a foam sheet manufacturing apparatus according to the present invention.
2 is a cross-sectional view showing the structure of a cooling unit according to the present invention.

Since the present invention can have various changes and can have various embodiments, specific embodiments will be described in detail in the detailed description.

However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

In the present invention, terms such as "comprises" or "have" are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, but one or more other features It is to be understood that this does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

In the present invention, "cell" means a microstructure expanded by foaming in a polymer.

Hereinafter, the present invention will be described in more detail.

Foam sheet manufacturing equipment

The present invention in one embodiment,

a hopper that feeds the resin melt;

an extruder having a die for extrusion molding into a foam sheet while discharging the resin melt supplied from the hopper; and

and a cooling unit having a mandrel disposed at the front end of the die.

The cooling unit provides an apparatus for manufacturing a foam sheet including an airing tunnel for injecting cooling gas in the direction of the outer circumferential surface of the mandrel.

The foam sheet manufacturing apparatus according to the present invention includes a hopper, an extruder and a cooling unit, and the cooling unit includes a mandrel and an airing tunnel located at a predetermined distance from the mandrel outer peripheral surface.

1 is a structural diagram showing a foam sheet manufacturing apparatus 100 of the present invention. Hereinafter, the foam sheet manufacturing apparatus 100 will be described with reference to FIG. 1 .

The foam sheet manufacturing apparatus 100 according to the present invention includes a hopper 110 positioned at the tip of the extruder 120 to supply the raw material of the foam sheet 1 .

The hopper 110 may supply a raw material of the foam sheet 1, for example, a polyethylene terephthalate (PET) chip together with an additive and a foaming agent.

Here, the hopper 110 may be heated to the melting point of the raw material, specifically, may be heated to a temperature of 90 ℃ to 300 ℃, more specifically 120 ℃ to 290%.

In addition, the hopper 110 may further include a deaerator (not shown) for the process of removing moisture from the raw material. For example, the hopper 110 may be heated to 90° C. to 110° C. to vaporize water present in the polymer resin as a raw material, wherein the vaporized water is a deaerator provided in the hopper 110 . (undisclosed) can be removed.

In addition, the raw material supplied through the hopper 110 is subjected to a foaming process while passing through the die 121 of the extruder 120, at this time, the temperature of the extruder 120 may be 240 ℃ to 280 ℃. .

In addition, the die 121 positioned at the rear end of the extruder 120 may be applied as a T-die commonly used in the art, but preferably an annular die may be applied.

When the annular die 121 is used, the annular die 121 extrudes and foams the resin melt in which the raw material is melted into a cylindrical body to manufacture a cylindrical body, and then gradually expands the diameter of the manufactured cylindrical body, and then the mandrel 131 ), through the process of supplying the resin melt can be foamed.

At this time, the ratio of the outer diameter (outer diameter) of the annular die 121 to the inner diameter (inner diameter) of the mandrel 131 located at the rear end of the annular die 121, that is, the blow-up ratio is preferably 2.5 to 3.5. .

In addition, in the foam seat manufacturing apparatus according to the present invention, the cooling unit 130 for cooling the foamed resin melt is a cylindrical mandrel 131 and an air ring for directly injecting a cooling gas 134 to the outer peripheral surface of the mandrel 131 . a tunnel 132 .

Here, the airing tunnel 132 may include an injection hole 133 for injecting the cooling gas 134 on the inner peripheral surface, and the injection hole 133 may be spaced apart from the outer peripheral surface of the mandrel 131 by 5 to 20 cm. and specifically 5 to 15 cm; 5 to 100 cm; 10 to 20 cm; It may also be spaced apart from 12 to 18 cm.

In addition, 3 to 10 injection holes 133 are disposed in the inner circumferential direction of the airing tunnel 132 , for example, in the circumferential direction of the mandrel 131 to form an air ring surrounding the mandrel 131 , such an air ring 2 to 10 pieces may be spaced apart in the longitudinal direction of the silver airing tunnel 132 .

As an example, 5 to 8 injection holes 133 are arranged in the inner circumferential direction of the airing tunnel 132 to form an air ring, and 4 to 8 air rings are spaced apart in the longitudinal direction of the airing tunnel 132 . can be placed.

As another example, 4 to 6 of the injection holes 133 are arranged in the inner circumferential direction of the airing tunnel 132 to form an air ring, and the air ring has 2 to 5 in the longitudinal direction of the airing tunnel 132 . may be spaced apart.

In addition, the airing tunnel 132 may selectively operate a plurality of air rings spaced apart in the longitudinal direction, and through this, the cooling unit 130, specifically, the airing tunnel 132 through which the foamed resin melt passes. The temperature between the inner peripheral surface and the outer peripheral surface of the mandrel 131 can be easily controlled.

As an example, the foam sheet manufacturing apparatus 100 of the present invention may be controlled so that the temperature of the cooling unit 130 and the extruder 120 satisfies the following Equation 1 by selectively operating a plurality of air rings:

[Equation 1]

_{┃T cooling} -T extruding ┃ ≥ 200℃

In Equation 1,

The T _cooling represents the temperature of the cooling unit 130,

The T _extruding indicates the temperature of the extruder 120 .

Equation 1 means that the temperature deviation of the cooling unit 130 and the temperature of the extruder 120 is 200 ℃ or more, the foam sheet manufacturing apparatus 100 according to the present invention 100 is 200 ℃ or more, 220 ℃ or more in Formula 1 , 240 °C or higher, 200 °C to 300 °C, or 200 °C to 250 °C can be controlled to satisfy.

At this time, the temperature of the cooling gas 134 injected from the airing tunnel 132 may be -20°C to 5°C, specifically, -10°C to 5°C or -5°C to 0°C.

The foam sheet manufacturing apparatus 100 according to the present invention selectively operates a plurality of air rings to control the temperature of the cooling unit 130 and the extruder 120 to satisfy Equation 1, thereby extruding and foaming from the annular die 121 Non-foaming or a skin layer including fine foamed cells may be formed on the surface of the resin melt. Here, the skin layer may be formed on the surface where the cooling gas 134 injected from the injection hole 133 of the airing tunnel 132 touches, for example, the upper surface of the foam sheet.

On the other hand, the surface temperature of the mandrel 131, that is, the temperature of the outer peripheral surface of the mandrel 131 is -10 to 20 ℃, specifically -5 to 15 ℃; -5 to 10°C; or 0 to 10°C. In this way, when the surface temperature of the mandrel 131 is adjusted within the above range, non-foamed or micro-foamed cells are formed on the surface where the cooling gas 134 injected from the injection port in contact with the surface of the mandrel 131 does not directly contact. It is possible to form a skin layer including, the foam sheet 1 manufactured through this may have a skin layer or a micro-foaming layer on both sides.

In addition, in the airing tunnel 132 , the ratio of the area in which the cooling gas 134 is injected to the area in which the cooling gas 134 is not injected, that is, the area in which the injection hole 133 is disposed and the area in which the injection hole 133 is not disposed in the airing tunnel 132 . The ratio may satisfy 0.05 to 0.5, specifically, 0.05 to 0.3; 0.05 to 0.1; 0.1 to 0.4; Or 0.1 to 0.25 may be satisfied.

In the present invention, by providing the airing tunnel 132 as described above on the outer circumferential surface of the mandrel 131, when the extruded resin melt moves while foaming, the cooling unit 130, specifically, the mandrel 131 outer circumferential surface and air ring The temperature of the space between the inner peripheral surfaces of the tunnel 132 may be adjusted to satisfy the condition of Equation 1 above.

Furthermore, the foam sheet manufacturing apparatus 100 according to the present invention may further include a cutter 140 for cutting the foam sheet 1 that has passed through the cooling unit 130 . Specifically, the resin melt extruded from the annular die 121 passes through the cooling unit 130 in a form surrounding the mandrel 131 at the same time as foaming to form the hollow foam seat 1 . The hollow foam seat 1 manufactured in this way may be expanded by cutting the side by the cutter 140 located at the rear end of the mandrel 131 .

As described above, the foam sheet manufacturing apparatus 100 according to the present invention directly injects the cooling gas in the direction of the outer circumferential surface of the mandrel through the airing tunnel, but the temperature of the extruder 120 and the temperature inside the cooling unit 130 . By maintaining it at a certain level, it is possible to form a skin layer containing non-foamed or fine foamed cells on the surface of the foaming layer containing uniform foamed cells therein without a separate process, so the manufacturing process of the foamed sheet 1 can be simplified. there is an advantage

foam sheet

In addition, the present invention in one embodiment,

Manufactured by the foam sheet manufacturing apparatus of the present invention,

polyester foam layer; And it provides a foam sheet comprising a skin layer located on one side or both sides of the polyester foam layer.

The foam seat according to the present invention has a structure including a skin layer on one or both sides of a polyester foam layer including uniformly foamed cells, wherein the skin layer is formed on the surface of the foam layer when the polyester foam layer is foamed. Since it is generated through rapid cooling, it may be composed of the same components as the foam layer, and may include non-foaming or fine foam cells.

In this case, the polyester foam layer may be uniformly foamed and the average size of the cells may be 100 to 300 μm. Specifically, the cell size of the foam layer may be an average of 120 to 225 μm, 150 to 250 μm, or 170 to 220 μm. It is possible to have excellent strength and heat resistance by having a cell of the same size as described above.

In addition, the size of the unfoamed or foamed cells of the skin layer may be remarkably small. Specifically, the cell size of the skin layer may be an average of 100 μm or less, and more specifically, an average of 0.1 to 100 μm, 5 to 80 μm, 10 to 50 μm, or 50 μm or less. The skin layer can improve the surface uniformity of the foam sheet by controlling the cell size as described above, and at the same time lower fluid permeability such as gas.

As an example, the foam sheet of the present invention may have a centerline surface roughness (Ra) of 0.1 µm to 1.5 µm, specifically 0.2 µm to 1.4 µm, 0.5 µm to 1.2 µm, or 0.8 µm to 1.1 µm . As an example, the center line roughness (Ra) of the foam sheet may be 0.8㎛ to 1.1㎛. In the present invention, through the centerline surface roughness value within the above range, it can be seen that the foam seat of the present invention has a skin layer uniformly formed on the surface.

Although the above has been described with reference to the preferred embodiment of the present invention, those skilled in the art or those having ordinary knowledge in the technical field will not depart from the spirit and technical scope of the present invention described in the claims to be described later. It will be understood that various modifications and variations of the present invention can be made without departing from the scope of the present invention.

Accordingly, the technical scope of the present invention is not limited to the content described in the detailed description of the specification, but should be defined by the claims.

1: Foam sheet
100: foam sheet manufacturing device
110: hopper
120: extruder
121: die
130: cooling unit
131: mandrel
132: airing tunnel
133: nozzle
134: cooling gas
140: cutter

Claims (9)

a hopper that feeds the resin melt;
an extruder having a die for extrusion molding into a foam sheet while discharging the resin melt supplied from the hopper; and
Containing; and
The airing tunnel injects cooling gas having an average temperature of -20°C to 5°C, the ratio of the area to which the cooling gas is injected and the area not injected satisfies 0.05 to 0.5, and selectively operates a plurality of air rings to control the internal temperature of the cooling unit,
The temperature of the cooling unit and the extruder satisfies Equation 1 below,
The manufactured foam sheet is a crystalline polyester foam sheet manufacturing apparatus having a structure in which a skin layer including non-foamed or micro-foamed cells is formed on the surface of a polyester foam layer containing uniform foam cells:
[Equation 1]
_{┃T cooling} -T extruding ┃ ≥ 200℃
In Equation 1,
The T _cooling represents the temperature of the cooling unit,
The T _extruding indicates the temperature of the extruder.
According to claim 1,
The airing tunnel is provided with an injection port for injecting a cooling gas on the inner peripheral surface,
The injection hole is a foam sheet manufacturing apparatus spaced apart from the outer peripheral surface of the mandrel 5 to 20 cm.
3. The method of claim 2,
In the airing tunnel, 3 to 10 injection holes form an air ring in the inner circumferential direction,
The air ring is a foam sheet manufacturing apparatus in which 2 to 10 are spaced apart in the longitudinal direction of the air ring tunnel.
delete delete delete delete According to claim 1,
The surface temperature of the mandrel is -10 to 20 ℃ foam sheet manufacturing apparatus.
According to claim 1,
The foam sheet manufacturing apparatus further comprises a cutter for cutting the foam sheet passing through the cooling unit.

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