KR200403676Y1 - flexible tube - Google Patents

Abstract

The present invention is in the manufacture of a flexible tube consisting of a thin aluminum plate and plastic material used for tube containers such as toothpaste, cosmetics, food, pharmaceuticals, etc., the laminated structure of the present invention is injection of the injection hole using the insert mold mold It is a laminated structure to prevent the damage (cracking) of the aluminum thin plate generated by high heat and high pressure during molding, and also minimizes the thickness of the aluminum thin plate in the longitudial seam of the tube body, thereby inducing high frequency induction heating and ultrasonic friction heat. It is a laminated structure to selectively apply the joint.

Description

Flexible tube

The present invention relates to a sheet structure in the form of a flexible tube commonly used for filling paste products, a manufacturing method, and a circular joint of a tube body. It consists of inner and outer heat adhesive layer, adhesive resin layer and inner barrier layer, and the base of inner barrier layer is used for the purpose of preventing ultraviolet ray blocking, gas permeation, moisture permeation, etc. by laminating aluminum sheet in single layer.

In the sheet structure of the flexible tube as shown in Fig. 1, the inner barrier layer was laminated with an aluminum thin plate alone, and a plurality of polymers were laminated with the inner surface layer 10 (polyethylene) / first adhesive resin layer ( 20) A flexible sheet in which (ethylene acrylic acid copolymer) / inner blocking layer 30 (aluminum thin plate) / second adhesive resin layer 40 (ethylene acrylic acid copolymer) / outer surface layer 50 (polyethylene) is laminated It is commonly used.

The circular joining method (b) of the tube body (a) includes an external heating method using a heating heater bar and an internal heating method using high frequency induction heating or ultrasonic frictional heating, but is generally bonded by an internal heating method. After the sealing method is to seal the inner surface layer by a high frequency induction heating method or hot-air (hot-air) to exhibit the function of the tube container.

As described above, the high-frequency induction heating bonding in the circular joining of the tube body heats the aluminum sheet, which is a metal layer, to melt the adhesive resin layer and the polyethylene film, which is heat-bonded layer, and pressurizes the tube to press the tube. In general, the thickness of the laminated base material is determined in consideration of adhesive strength.

Ultrasonic frictional heat bonding, on the other hand, generates ultrasonic friction at the polyethylene interface of the inner and outer surface layers to generate frictional heat, and at the same time, pressurizes and applies a constant pressure to obtain adhesive strength.

In the injection mold of the opening using the tube body and the insert mold mold, the injection pressure using the polyethylene resin is 28 to 50 Kgf / cm 2, and the temperature of the injection resin is 260 to 310 ° C. When the inner surface layer of the melt is integrated by the injection heat, there is a problem that damage (crack) of the aluminum thin plate is caused by the injection pressure. In other words, the polyethylene surface of the inner surface layer bonded to the aluminum sheet and the ethylene acrylic acid copolymer resin of the adhesive resin layer have a softening point of 100 ° C. or less, which leads to loss of rigidity due to the heat of the injection resin and cracking of the aluminum sheet due to the injection pressure. have.

As described above, it is common to solve the problem by the strength (heat treatment change, alloy) and thickness of the aluminum thin plate as an example for preventing the damage of the thin aluminum sheet in the injection molding having a plurality of insert molds. As an example of an insert mold mold for producing a plurality of tubes, as in the case of Korea Patent Publication No. 10-0363996 registered a mold mold structure for producing a plurality of tubes, this is a plurality of tube forming mold for mass production purposes It is a structure commonly used for the manufacture of tube containers using metal molds.

In the sheet structure of a tube body used in the manufacture of a conventional flexible tube container, a phenomenon as shown in <Table 1> can be confirmed by comparing the bonding relationship between the injection pressure and the tube body with the thickness of the aluminum thin plate.

<Table 1>

The results of <Table 1> show that the high frequency induction heating bonding does not damage the aluminum sheet in the welding method of the tube body, but in the case of the ultrasonic bonding, cracking occurs due to the thickness difference (BCD type) of aluminum. In case of type A, the cut portion exposed to the outer layer was precipitated in an aqueous solution of sodium hydroxide, and as a result, it was confirmed that the resin film layer was partially formed on the cut surface of the sheet and the aluminum sheet was eroded.

In the tube body welding as described above, in order to obtain a constant bond strength (0.3kg) in the state of overlapping the upper and lower overlapping portion of the joining part 2mm overlap, the joining pressure should be pressurized to 3.0Kgf / ㎠ level, the compressibility is 20 ~ 30% Maintaining this level can prevent leakage and achieve a certain burst strength.

In addition, in the production method using a plurality of insert mold molds for the purpose of mass production as shown in <Table 1>, it can be confirmed that cracks are generated due to the injection pressure as shown in <Table 1> by the strength or thickness of the aluminum sheet. That is, the polyethylene of the inner surface layer laminated with the aluminum thin plate and the ethylene acrylic acid copolymer of the first and second adhesive layers decrease in strength due to the softening phenomenon caused by the injection temperature during injection molding, and thus the heat transfer portion of the injection resin of the tube body. On the boundary line of (e) it can be confirmed that the aluminum sheet is cracked by the injection pressure.

As described above, the flexible tube is composed of a thin aluminum sheet as an inner barrier layer and laminated with a plurality of polymers, and is an example of a tube for improving chemical resistance, bending stability, gas barrier, moisture barrier, etc., Korean Patent Publication No. 1991 -08844 (Application No. 1984-0001766) discloses a multilayer flexible substrate in the form of a flexible tube commonly used to fill paste-like products and the use of these substrates. Utility Model Publication No. 2004-0348800 discloses a flexible tube sheet structure for an ultrasonic welding method.

In the case of forming a gas barrier layer using a single layer of aluminum sheet, it can be seen that there are many problems in storage resistance in the manufacturing process due to the change of injection molding and welding method, which has a detrimental effect on lowering productivity and increasing production cost. To provide.

The present invention is suitable for mass production using a plurality of insert mold molds in the manufacture of a flexible tube laminated with a thin aluminum sheet and a plastic substrate, and provides a single sheet capable of high frequency induction heating bonding and ultrasonic friction heat bonding in a welding method. It is. In the manufacture of the tube using the sheet, a sheet having a laminated structure suitable for preventing the cracking of the aluminum sheet in the bonding process and the injection molding process, satisfying the gas barrier effect which is the highest object of laminating the aluminum sheet, and suitable for storage resistance To do it.

The flexible tube sheet of the present invention for realizing the above object is normally joined by an internal heating method in a tube body joining process, so that high frequency induction heating joining and ultrasonic friction heat joining are possible. The present invention provides a sheet having a laminated structure which not only prevents cracking of an aluminum sheet by external heating but also prevents cracking of an aluminum sheet due to injection pressure due to the shape of a mold mold in injection molding.

The laminated structure of the sheet for realizing the object of the present invention is a multi-layered sheet structure having two outer surface layers and a plurality of inner blocking layers, and the sheet structure is shown in Fig. 2 above to be suitable for circular bonding. Similarly, the stacking order of the sheets has a lamination structure in the order of the inner surface layer 10 / the first adhesive resin layer 20 / the inner blocking layer 30 / the second adhesive resin layer 40 / the outer surface layer 50.

The inner blocking layer 30 of the flexible tube of the present invention is made of aluminum thin plate 301 / adhesive 302 / plastic film 303 / adhesive 304 / adhesive plastic film 305 as shown in <Fig. 3>. ) Is made of a multilayer composite substrate sequentially laminated using a dry lamination method. Peeling strength is maintained at 8 N / 15mm or more in the bonding of the aluminum thin plate 301 and the plastic film 303.

The action of the plastic film 303 laminated on the inner blocking layer 30 is in the circular joint (b) of the tube body (a), the crack of the aluminum sheet due to the pressure (2.5 ~ 3.5Kgf / ㎠) during ultrasonic welding In addition, softening of the inner surface layer and the adhesive resin layer due to the heat of the injection resin (280 to 310 ° C.) during injection molding causes the aluminum sheet due to the injection pressure to be formed on the boundary between the injection resin and the tube body (e). Laminate for the purpose of reinforcement to prevent cracking. In order to realize this, the basic properties of the plastic film 303 are ideally laminated with a film having a tensile strength of 1,000 kg / cm 2 or more, an elongation of 130% or less, and a softening point of 150 ° C. or more. It is preferable to selectively use a film that satisfies the conditions.

<Table 2>

The action of the adhesive plastic film 305 laminated on the inner barrier layer 30 is the adhesion between substrates (bonding by the plastic film 303 and the dry lamination method, bonding by the outer surface layer 50 and extrusion laminate), Due to frictional heat generated during ultrasonic welding, lamination is prevented due to the difference in thermal strain stress between substrates (dilamination phenomenon) and laminated for the purpose of forming a printed layer when applying a gravure printing method. In order to achieve this, the adhesive plastic film 305 may preferably use a polyethylene film having a softening point / melting point higher than that of the adhesive resin 40. For this purpose, in the present invention, a linear low density polyethylene (LLDPE.C-6) film or a low density Laminate polyethylene (LDPE) film.

The adhesive of the internal barrier layer 302.304 is characterized by using a polyurethane-based adhesive having a heat resistance at 240 ℃ or more. This is to prevent the adhesive separation (delamination phenomenon) by heat of the injection resin during injection molding, and also to prevent the adhesive separation (delamination phenomenon) by the temperature of the heating element (190 ℃) during the high frequency induction heating bonding of the tube body. to be.

The inner surface layer 10 and the outer surface layer 50 of the present invention preferably use linear low density polyethylene (LLDPE-C6) among polyethylene resins excellent in heat-sealing strength and excellent in oil resistance and chemical resistance. In order to diversify, the polyethylene laminated on the outer surface layer 50 is preferably laminated with an inflation film obtained by co-extrusion of high density polyethylene and linear low density polyethylene in order to maintain dimensional stability.

In the adhesive resins 20 and 40 of the present invention, it is preferable to use a resin having a lower melting point than the polyethylene of the surface layers 10 and 50. In this case, the softened adhesive resin is pushed out to form the molten resin and the resin film of the surface layers 10 and 50 by the pressure at the time of the circular joining of the tube body. This is to allow the resin film to surround the cut portion and to prevent erosion of the aluminum sheet.

As the method of extrusion bonding the adhesive resin, a method of extrusion bonding with an inflation film and a method of coextrusion and coating a bonding resin and a polyethylene resin may be applied. The extrusion bonding resin of the aluminum thin plate layer 301 and the polyethylene of the first heat-adhesive layer 10 uses an ethylene acrylic acid copolymer adhesive resin 20 to exert an ionic bond (hydrogen bond) by high temperature. In addition, in order to bond the polyethylene film of the adhesive plastic film 305 layer with the polyethylene of the second thermal adhesive layer 50, the polyethylene resin 40 is used to exert crosslinking at high temperature.

As described above, the present invention relates to a stacking structure and a manufacturing method of a sheet for preventing cracking of an aluminum sheet in joining and injection molding of a tube body in order to manufacture a flexible tube in which an aluminum sheet and a plastic are laminated.

Hereinafter, the configuration and effects of the present invention will be described in more detail with reference to Examples 3, but the scope of the present invention is not limited to the following examples.

<Table 3>

In the above embodiment, the internal barrier layer is laminated by a dry laminate method, and the polyethylene inflation films (LLDP, C6) are extruded and laminated on the inner and outer surface layers. In the embodiment of <Table 3>, the plastic film 303 formed in the internal barrier layer exhibits a function of preventing cracking of the aluminum thin plate and improving the resilience of the tube. Example B can be selected as the best lamination structure, and another method is to laminate the inner barrier layer by dry lamination method, and to coat the inner and outer surface layers by coextrusion coating of adhesive resin and polyethylene resin. As in the embodiment, the sheet of the final flexible tube had a gas barrier effect of 0.000 cm 3 / m 2, 24hrs, atm and a moisture permeability of 0.00g / m 2, 24hrs.

In another embodiment, the inner barrier layer 30 is laminated by a dry lamination method as in the stacking structure of <Table 3>, and the inner surface layer 10 and the aluminum thin layer layer 301 are extruded and laminated with ethylene acrylic copolymer resin. And bonded by high frequency induction heating or ultrasonic friction heat, and selectively applying polyethylene and polypropylene resin to the surface of the adhesive plastic layer 305 using an extrusion coating machine as shown in <Fig. 4>. d) and cut to the practical standard according to the drawing direction. The extruded coated tube body completes the process of forming the opening, bonding the lead seal, and sealing the cap to complete the tube.

In the laminated structure, the thickness of the adhesive plastic layer 305 is most ideally laminated at a thickness of 300 to 350% of the thickness of the aluminum thin plate 301 / adhesive 302 / plastic film 303 laminated. This is for the purpose of preventing the erosion of the aluminum thin plate cut part by melting the interface of the adhesive plastic layer and forming a resin film on the sheet cut part.

The flexible tube sheet constructed and operated as described above is suitable for mass production using a plurality of insert mold molds, and provides a single sheet capable of high frequency induction heating bonding and ultrasonic friction thermal bonding in a welding method. This minimizes the thickness of the aluminum thin plate to improve the restoring force, and also to prevent the degradation of the contents retention due to the pinhole generation of aluminum due to bending of the tube body.

In particular, the existing flexible tube sheet (aluminum thin plate: 40㎛) capable of ultrasonic friction thermal joining and the sheet according to the present invention can guarantee the same performance in terms of functionality, while significantly reducing the amount of expensive aluminum sheet used in terms of manufacturing cost. It offers economic benefits that can be saved.

1. Circular junction cross section of flexible tube

2. Cross section of the laminated structure of the sheet according to the present invention.

3. Sectional drawing which shows the Example which comprises the internal blocking layer of the sheet which concerns on this invention.

4. Sectional drawing which showed the Example which extrusion-coated polyethylene resin to the tube body which joined the sheet | seat according to this invention.

<Description of the code | symbol about the principal part of drawing>

a: tube body b: circular joint of tube body

c: over-lap d: extrusion coating of polyethylene resin

e: boundary between injection resin and tube

10: inner surface layer 20: first adhesive resin layer

30: internal barrier layer 40: second adhesive resin layer

50: outer surface layer

301: aluminum thin layer of the internal barrier layer

302: adhesive layer of the internal barrier layer

303: plastic film layer of the internal barrier layer

304: adhesive layer of the internal barrier layer

305: adhesive plastic film layer of the internal barrier layer

Claims (5)

The first thermal adhesive layer 10 of the inner surface layer constituting the inner surface of the flexible tube and the second thermal adhesive layer 50 of the outer surface layer constituting the outer surface, an internal barrier layer 30 that prevents gas permeation into the tube, and the surface layer In the flexible tube of the sheet consisting of adhesive resin layers (20, 40) for adhering the internal barrier layer, The substrate of the first and second thermal adhesive layers is laminated with polyethylene, The resin of the first adhesive layer 20 is laminated with an ethylene acrylic acid copolymer, The resin of the second adhesive layer 40 is laminated ethylene copolymer or polyethylene, The inner blocking layer 30 is formed by sequentially laminating an aluminum thin plate 301, an adhesive layer 302, a plastic film 303, an adhesive layer 304, and an adhesive plastic film 305. Flexible tube of sheet to say. An outer surface layer 50 forming an outer surface and a first thermal adhesive layer 10 of an inner surface layer forming an inner surface of the flexible tube, an inner blocking layer 30 that prevents gas permeation into the tube, and an inner surface layer and an inner blocking layer. In the flexible tube of the sheet consisting of an adhesive resin layer 20 for bonding the The base of the first heat adhesive layer is laminated with polyethylene, The outer surface layer 50 is laminated with polyethylene or polypropylene by extrusion coating, The resin of the first adhesive layer 20 is laminated with an ethylene acrylic acid copolymer, The inner blocking layer 30 is formed by sequentially laminating an aluminum thin plate 301, an adhesive layer 302, a plastic film 303, an adhesive layer 304, and an adhesive plastic film 305. One sheet of flexible tube. The flexible tube of a sheet according to any one of claims 1 to 2, which is joined by high frequency induction heating or ultrasonic frictional heat for the tube body joining (b) of the flexible tube. The flexible tube of the sheet according to any one of claims 1 to 2, wherein the adhesive plastic film of the inner blocking layer is laminated with an inflation film of linear low density polyethylene or low density polyethylene. The flexible tube of the sheet according to any one of claims 1 to 2, wherein the plastic film of the inner barrier layer is any one of a biaxially stretched polyester film, a biaxially stretched nylon film, and a biaxially stretched polypropylene film. .