Patent Application
20170106582
The present invention relates to a transparent plastic container, and a method for producing the same. In particular, the invention relates to a transparent plastic container that may be laser-welded even though the transparent plastic container does not contain a significant quantity of laser absorber and has excellent transparency, and a method for efficiently producing the transparent plastic container.
Recently, when various molded articles such as an automobile part, an electricity part, an electronic part, a machine part, a building part, a household part, etc. are configured, a black-based resin molded article formed using a laser welding method in place of ultrasonic welding, an adhesive, etc. has been proposed.
For example, a black-based secondary fabrication resin product has been proposed, and the resin product is formed by irradiating a surface of a resin component containing a laser-absorbent black colorant with predetermined laser through a resin product containing a laser-transmitting black colorant, and laser-welding a bonding surface (for example, see Patent Documents 1 and 2).
That is, Patent Document 1 discloses a black-based laser welding composite, etc. that can be laser-welded by containing a black dye to absorb most of an emitted laser beam.
More specifically, the laser welding composite is a laser welding resin composite containing a resin and a laser beam-absorbent colorant, and is a laser welding composite characterized in that, when laser transmittance with respect to 940 nm laser light in a state of containing a laser beam-absorbent black colorant is set to Tlaser-absorbent black resin, and laser transmittance with respect to 940 nm laser light with a resin alone is set to Tnatural resin, Tlaser-absorbent black resin/Tnatural resin is within a range of 0 to 0.2, and the laser beam-absorbent black colorant contains a mixture of carbon black and a nigrosine dye.
In addition, Patent Document 2 discloses a thermo-plastic resin composite which appears black and may transmit a laser beam in a wavelength within an infrared region.
More specifically, the resin composite is a laser welding resin composite containing a resin and a laser beam-transmitting colorant, and is a laser welding resin composite in which, when laser transmittance with respect to 940 nm laser light in a state of containing a laser beam-transmitting black colorant is set to Tlaser-transmitting black resin, and laser transmittance with respect to 940 nm laser light with a resin alone is set to Tnatural resin, Tlaser-transmitting black resin/Tnatural resin is within a range of 0.5 to 1.2, and the laser beam-transmitting black colorant contains an anthraquinone dye or a monoazo complex dye.
In addition, Patent Document 3 discloses a laser welding method capable of reliably sealing a container and a cover in a short time.
More specifically, in a sealing method using laser welding of the container and the cover, the sealing method is characterized in that one side includes a laser-transmittable thermo-plastic resin, the other side includes a resin composite in which a pyrogenic substance that generates heat by absorbing a laser is contained in a thermo-plastic resin, laser beam emitted from a laser irradiation device is a rectangular beam having a uniform light intensity distribution, an upper limit of a temperature that rises by laser irradiation on a welding interface between the container and the cover falls within a range above or equal to a melting point of the thermo-plastic resin and below a thermal decomposition start temperature, and an upper temperature limit is reached in a heating time t (msec) represented by Equation (1) below.
t(msec)=L/S (1)
(In the Equation, L denotes a length (mm) of the rectangular beam in a scan direction, and S denotes a scan speed (mm/msec) of a laser below or equal to 1.65 mm/msec.)
Patent Document 1: JP 404063 B1 (Claims)
Patent Document 2: JP 4734303 B1 (Claims)
Patent Document 3: JP 2013-203052 A (Claims)
However, the black-based resin molded article, which is disclosed in Patent Document 1, including a combination of a resin that can be laser-welded, etc. lacks decorativeness, and has a problem that the black-based resin molded article is prone to be restrictively used as a cosmetics container, a medical container, etc. which require a certain level of transparency such that content is visually recognized.
In addition, the black-based resin molded article of Patent Document 2 uses a combination of an anthraquinone dye and a monoazo dye as a black dye, and has problems that a colorful container of green, blue, red, purple, etc. may not be obtained, and, in particular, the black-based resin molded article is prone to be restrictively used as a cosmetics container, a medical container, etc. which require transparency.
Further, with regard to the sealing method using laser welding of the container and the cover disclosed in Patent Document 3, a predetermined quantity of a pyrogenic substance that generates heat by absorbing a laser needs to be contained, and there is a problem that the sealing method is prone to be restrictively used for a cosmetics container, a medical container, etc. which require transparency.
In this regard, as a result of a keen examination, the inventors have found that a predetermined portion, which may correspond to a combination of a main body/cover of a transparent plastic container made of a transparent resin, may be stably laser-welded in a short time without mixing a significant quantity of a laser absorber by considering a wavelength, etc. of a laser to be used, and completed the invention.
In other words, an object of the invention is to provide a transparent plastic container formed by laser welding even though the transparent plastic container has excellent transparency, and a method for efficiently producing the transparent plastic container.
According to the invention, a transparent plastic container including a cover portion made of a transparent polyester resin and a main plastic container body made of a transparent polyester resin, wherein the cover portion is welded to the main plastic container body by a long-wavelength laser having a wavelength of above or equal to 1.0 μm is provided, and the above-described problems may be solved.
In other words, when a long-wavelength laser having a predetermined wavelength is used, it is possible to provide a transparent plastic container obtained by being strongly laser-welded even though the transparent plastic container does not contain a significant quantity of laser absorber and has excellent transparency.
In addition, when the transparent plastic container of the invention is configured, it is preferable that the cover portion has a protrusion pressed against an inner wall of the main plastic container body, and the protrusion is welded to a portion of the inner wall of the main plastic container body by condensed light of the long-wavelength laser.
When a shape of the cover portion, etc. is considered, and a light condensing property of the long-wavelength laser is considered as described above, it is possible to obtain an excellent laser welding property while preventing occurrence of blistering or deformation in a laser welding portion.
In addition, when the transparent plastic container of the invention is configured, it is preferable that a long-wavelength laser transmittance is set to a value below or equal to 30% in the transparent polyester resin included in the cover portion and the transparent polyester resin included in the main plastic container body, or in one of the transparent polyester resins.
When a long-wavelength laser transmittance in the transparent polyester resin is considered as described above, it is possible to obtain a predetermined laser welding property while preventing occurrence of blistering or deformation in the laser welding portion.
In addition, when the transparent plastic container of the invention is configured, it is preferable that the transparent polyester resin included in the cover portion and the transparent polyester resin included in the main plastic container body, or one of the transparent polyester resins contains at least one of polycyclohexanedimethylene terephthalate, alcohol-modified polycyclohexanedimethylene terephthalate, and glycol-modified polycyclohexanedimethylene terephthalate as a main component.
When a type of the transparent polyester resin is considered as described above, it is possible to further enhance the laser welding property in the cover portion and the main plastic container body when compared to another polyester resin, etc.
In addition, another aspect of the invention is a method for producing a transparent plastic container including a cover portion made of a transparent polyester resin and a main plastic container body made of a transparent polyester resin, the method including a process (1) of preparing the cover portion made of the transparent polyester resin and the main plastic container body made of the transparent polyester resin, and a process (2) of irradiating a welding-scheduled portion of the cover portion and the main plastic container body with a long-wavelength laser having a wavelength of above or equal to 1.0 μm to weld the welding-scheduled portion.
In other words, when a long-wavelength laser having a predetermined wavelength is used, it is possible to efficiently produce a laser-welded transparent plastic container even though the transparent plastic container does not contain a laser absorber and has excellent transparency (high visible light transmittance).
In addition, when the method for producing the transparent plastic container of the invention is implemented, it is preferable that the long-wavelength laser is emitted while the cover portion and the main plastic container body are rotated in a press-fitting state.
When the long-wavelength laser is emitted in a rotated state as described above, it is possible to obtain a predetermined laser welding property while preventing occurrence of blistering or deformation in a laser welding portion.
In addition, when the method for efficiently producing the transparent plastic container of the invention is implemented, it is preferable that the long-wavelength laser is emitted through a condensing lens.
When the long-wavelength laser is emitted through the condensing lens as described above, it is possible to control a laser absorbing property in the welding-scheduled portion, and to obtain a predetermined laser welding property while preventing occurrence of blistering or deformation.
In addition, when the method for efficiently producing the transparent plastic container of the invention is implemented, it is preferable that the long-wavelength laser is emitted while being condensed, and a focal position of the long-wavelength laser is formed behind the welding-scheduled portion.
When the focal position of the long-wavelength laser is considered, it is possible to control a laser absorbing property in the welding-scheduled portion, and to obtain a predetermined laser welding property while preventing occurrence of blistering or deformation.
As illustrated in
Hereinafter, a detailed description will be given of the transparent plastic container 10 of the first embodiment formed by being welded using a long-wavelength laser having a predetermined wavelength for each constituent element.
1. Cover Portion
(1) Shape
A shape of the cover portion 14 illustrated in
More specifically, as illustrated in
In addition, an annular flange portion 14b is provided immediately above the annular protrusion 14a to extend in a horizontal direction, and is preferably configured to come into contact with an upper surface 12e of the cylindrical main plastic container body 12.
Therefore, a wall portion 14c extending in a perpendicular direction (vertical direction) is included immediately above the annular flange portion 14b as illustrated in
In other words, a reason therefor is that, when the cover portion 14 is configured as described above, excessive deformation or non-uniform welding of a laser welding portion may be effectively prevented without performing pressing using a jig, etc. from the outside at the time of performing laser welding as illustrated in
As illustrated in
Besides, it is preferable to provide a spray head 14′, or an inside plug or an inner lid (not illustrated) made of olefin resin between the cover portion 14 and the cap 16 in order to improve usability of the transparent plastic container 10.
(2) Transparent Polyester Resin
In addition, the transparent polyester resin contained in the cover portion 14 illustrated in
Herein, the predetermined polyester resin preferably corresponds to one or a combination of two or more of polycyclohexanedimethylene terephthalate (PCT), alcohol-modified polycyclohexanedimethylene terephthalate (PCTA), glycol-modified polycyclohexanedimethylene terephthalate (PCTG), etc.
A reason therefor is that these polyester resins having a cyclic ring structure may further increase a laser welding property between the cover portion and the main plastic container body when compared to another polyester resin, etc.
Another reason therefor is that, when these polyester resins are used, a cover portion having high transparency and more luxurious feeling may be provided even when a non-carbon black-based black pigment is mixed as a colorant.
Still another reason therefor is that, when these polyester resins are used, mechanical strength, durability, etc. of the cover portion may be significantly improved.
PCT is a polyester resin, in which thermal crystallization is suppressed, formed by allowing dicarboxylic acid containing terephthalic acid as a main component to react with a diol component containing 1,4-cyclohexanedimethanol (CHDM) as a main component. Examples of an article on the market thereof include a polycyclohexylene dimethylene terephthalate (or a thermx polyester resin (trademark) manufactured by Eastman Chemical Company), etc.
In addition, PCTA is a polyester resin, in which thermal crystallization is suppressed, formed by allowing dicarboxylic acid containing terephthalic acid and isophthalic acid as main components with a diol component containing 1,4-cyclohexanedimethanol (CHDM) as a main component. Examples of an article on the market thereof include EastarAN014 and AN004 manufactured by Eastman Chemical Company, etc.
Further, PCTG is a polyester resin, in which thermal crystallization is suppressed, formed by allowing dicarboxylic acid containing terephthalic acid as a main component with a diol component containing 1,4-cyclohexanedimethanol (CHDM) and ethylene glycol as main components. Examples of an article on the market thereof include EastarDN011 and DN004 manufactured by Eastman Chemical Company, etc.
(3) Visible Light Transmittance
In addition, even though the transparent polyester resin contained in the cover portion 14 is basically transparent, the transparent polyester resin preferably has a predetermined visible light transmitting property by appropriately adjusting a type, a mixed amount, etc. of the colorant to assign luxurious feeling.
Therefore, visible light transmittance (a value measured in accordance with JIS R 3212, for example, a wavelength of 500 nm) is preferably above or equal to 70%, more preferably set to a value within a range of 80 to 99.9%, and even more preferably set to a value within a range of 90 to 99%.
Further, when the visible light transmittance is controlled within the above-described range, an absorption rate of a long-wavelength laser (for example, a wavelength of 1.0 to 2.2 μm) may be indirectly controlled to a value above or equal to 70%.
More specifically, a specimen may be set on a spectrophotometer (manufactured by JASCO Corporation, item number: V-570 type), light transmittance of the specimen (thickness: 2 mm) may be measured in a wavelength range of λ=1.2 to 2.2 μm, and a laser absorption rate may be conveniently calculated from transmittance in a wavelength of 2.0 μm.
(4) Additive
In addition, it is preferable to mix various additives with the transparent polyester resin contained in the cover portion 14 on the assumption that a predetermined visible light transmittance may be maintained.
More specifically, examples of the additive include one or a combination of two or more of an ultraviolet absorbing agent, an anti-oxidizing agent, a dehydrating agent, a filler, a conductive material, a heat-conductive material, a plasticizer, anhydrous silica, amide wax, isoparaffin, a flame retardant, a functional oligomer, a coupling agent, etc.
In addition, when an additive is added, even though a mixed amount thereof depends on a type of the additive, the mixed amount is preferably set to a value within a range of 0.01 to 20 parts by weight, more preferably set to a value within a range of 0.05 to 8 parts by weight, and even more preferably set to a value within a range of 0.1 to 1 part by weight with respect to 100 parts by weight of the polyester resin.
Moreover, it is found that a laser welding property between the main plastic container body and the cover portion may be controlled when a predetermined amount of an ultraviolet absorbing agent such as 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, etc. is mixed, and the ultraviolet absorbing agent is a suitable additive.
2. Main Plastic Container Body
(1) Shape 1
In addition, even though a shape of the main plastic container body 12 illustrated in
Further, in order to maintain the external shape such as the cylindrical shape, etc., and obtain an excellent laser welding property, a wall thickness of a side wall is preferable set to a value within a range of 0.3 to 5 mm, more preferable set to a value within a range of 0.8 to 3 mm, and even more preferable set to a value within a range of 1 to 2 mm.
In addition, as illustrated in
A reason therefor is that, when the hollow thick portion 12c in the conic shape is provided on the bottom portion 12d corresponding to the lowest surface of the main plastic container body 12, it is possible to exhibit spindle effect, remarkably improve stability of the main plastic container body 12, and effectively prevent falling down even when content is accommodated.
Another reason therefor is that, when the hollow thick portion 12c in the conic shape is included, and when content is taken out, the content may be taken out without leaving residue using a nozzle, etc.
Moreover, when the hollow thick portion 12c in the conic shape is included, light entering the inside of the main body is complicatedly reflected, decorative effect is enhanced, and luxurious feeling as in glass is created.
Therefore, a thickness (t) of the thick portion is preferably set to a value within a range of 8 to 20 mm, more preferably set to a value within a range of 10 to 18 mm, and even more preferably set to a value within a range of 12 to 15 mm.
(2) Shape 2
In addition, as illustrated in
In other words, it has been confirmed that resin expands to some extent when transparent polyester resins are laser-welded together, and it is preferable to provide a shape in which the inner wall of the main plastic container body 12 extending in the perpendicular direction is inclined from an inner side to an outer side, that is, a reverse tapered inclined plane, and to include a space portion that absorbs expansion of the transparent polyester resin.
Therefore, based on the reverse tapered inclined plane, as illustrated in
(3) Transparent Polyester Resin
In addition, the transparent polyester resin included in the main plastic container body 12 preferably contains, as a main component, one or a combination of two or more of polycyclohexanedimethylene terephthalate, alcohol-modified polycyclohexanedimethylene terephthalate, glycol-modified polycyclohexanedimethylene terephthalate, etc.
A reason therefor is that a laser welding property may be remarkably improved when the same type of suitable polyester resin contained in the cover portion is used.
As described in the foregoing, another reason therefor is that, when a polyester resin having the cyclic ring structure is used, the laser welding property between the cover portion and the main plastic container body may be further enhanced when compared to another polyester resin, etc.
Still another reason therefor is that, when the polyester resin is used, a more colorful main plastic container body having high transparency may be provided even when a colorant is mixed. Further, when the polyester resin is used, mechanical strength, durability, etc. of the main plastic container body may be remarkably improved.
(4) Visible Light Transmittance
In addition, the transparent polyester resin included in the main plastic container body 12 illustrated in
Therefore, the visible light transmittance of the transparent polyester resin is preferably set to a value above or equal to 70%, more preferably set to a value within a range of 80 to 99.9%, and even more preferably set to a value within a range of 90 to 99%.
Further, when the visible light transmittance is controlled within the above-described range, an absorption rate of a long-wavelength laser (for example, a wavelength of 1.0 to 2.2 μm) may be indirectly controlled to a value above or equal to 70%.
(5) Additive
In addition, it is preferable to mix various additives similar to those in the cover portion 14 with the transparent polyester resin included in the main plastic container body 12 in a range in which visible light transmittance may be maintained.
In addition, when an additive is added, even though a mixed amount thereof depends on a type of the additive, the mixed amount is preferably set to a value within a range of 0.01 to 20 parts by weight, more preferably set to a value within a range of 0.05 to 8 parts by weight, and even more preferably set to a value within a range of 0.1 to 1 part by weight with respect to 100 parts by weight of the polyester resin.
Moreover, it is found that a laser welding property between the main plastic container body and the cover portion may be controlled when a predetermined amount of an ultraviolet absorbing agent such as 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, etc. is mixed, and the ultraviolet absorbing agent is a suitable additive.
3. Transparent Plastic Container
(1) Shape
In addition, even though a basic shape of the transparent plastic container 10 including the predetermined cover portion 14 and the main plastic container body 12 is not particularly restricted, the shape is roughly a cylindrical shape having a lid as illustrated in
In addition, it is preferable to form a shape having a spiral pattern on the inner surface of the main plastic container body, etc. or to form a shape having a stripe pattern on the inner surface of the main plastic container body, etc. in order to further improve luxurious feeling or decorativeness.
Further, although not illustrated, it is preferable to provide an organic decoration layer, a metal decoration layer, a hot stamp layer, a delustering surface layer, a light reflection layer, etc. to cover the laser welding portion in order to further improve luxurious feeling or decorativeness as the transparent plastic container.
(2) Laser Welding Portion
In addition, the laser welding portion (welding-scheduled portion) 12′ illustrated in
More specifically, the laser welding portion 12′ illustrated in
Herein, a reason for using the long-wavelength laser 50′ having the wavelength of above or equal to 1.0 μm will be described by mentioning
In other words, a horizontal axis of
As a characteristic curve in
However, when the wavelength of the long-wavelength laser is excessively large, stable power of the long-wavelength laser is difficult to obtain, a type of a constituent material of the long-wavelength laser is excessively restricted, and thus the long-wavelength laser is difficult to be manufactured at a low price.
Therefore, the wavelength of the long-wavelength laser may be preferably set to a value within a range of 1.2 to 2.5 μm, and more preferably set to a value within a range of 1.8 to 2.2 μm.
It has been confirmed that a similar tendency is obtained even when the vertical axis of
A second embodiment is a method for producing the plastic container 10 including the cover portion 14 made of the transparent polyester resin and the main plastic container body 12 made of the transparent polyester resin illustrated in
(1) Process of preparing the cover portion 14 made of the transparent polyester resin and the main plastic container body 12 made of the transparent polyester resin
(2) Process of irradiating the welding-scheduled portion of the cover portion 14 and the main plastic container body 12 with the long-wavelength laser having the wavelength of above or equal to 1.0 μm to weld the welding-scheduled portion
Hereinafter, the method for producing the transparent plastic container 10 as the second embodiment will be described in detail while appropriately omitting content overlapping the first embodiment.
1. Process (1)
Process (1) is a process preparing the cover portion 14 made of the transparent polyester resin and the main plastic container body 12 made of the transparent polyester resin illustrated in
In more detail, it is preferable to use a conventionally known injection molding machine, normally set an injection temperature of an injection molding device to a range of 250 to 300° C. and an injection pressure thereof to a range of 200 to 800 kgf/cm2, and injection-mode the cover portion and the main plastic container body made of the transparent polyester resin, thereby preparing the cover portion and the main plastic container body.
2. Process (2)
(1) Wavelength/Power/Irradiation Time of Long-Wavelength Laser
Process (2) is a process of irradiating the welding-scheduled portion of the cover portion and the main plastic container body with the long-wavelength laser having the wavelength of above or equal to 1.0 μm to weld the welding-scheduled portion.
In addition, as illustrated in
Conversely, a long-wavelength laser having a wavelength of below 1.0 μm has difficulty in performing practical laser welding between transparent polyester resins even when an irradiation time or power is appropriately changed.
In addition, the welding-scheduled portion is preferably laser-welded using the predetermined long-wavelength laser irradiation device 50 illustrated in FIGS. 2(a) to 2(c) by normally setting long-wavelength laser power to a range of 5 to 40 W and a long-wavelength laser irradiation time to a range of 5 to 30 seconds.
A reason therefor is that, when long-wavelength laser power is below 5 W, laser welding between transparent polyester resins is practically difficult even when irradiation is performed for a long time.
In addition, a reason therefor is that, when long-wavelength laser power is above 40 W, stable power of the long-wavelength laser is difficult to be obtained, a type of a constituent material of the long-wavelength laser is excessively restricted, and thus the long-wavelength laser is difficult to be manufactured at a low price in some cases.
Meanwhile, a reason therefor is that, when an irradiation time of the long-wavelength laser is below 5 seconds, laser welding between transparent polyester resins is insufficient unless long-wavelength laser power is considerably increased.
In addition, a reason therefor is that, when an irradiation time of the long-wavelength laser is above 30 seconds, stable power of the long-wavelength laser is difficult to be obtained, or the welding-scheduled portion is difficult to be uniformly laser-welded in some cases.
Therefore, it may be more preferable to set power of the long-wavelength laser to a value within a range of 6 to 20 W, and set a long-wavelength laser irradiation time to a value within a range of 6 to 25 seconds when transparent polyester resins are laser-welded.
Moreover, it is preferable to incorporate a fiber laser as a long-wavelength laser oscillator, and repeat amplification and oscillation while a laser beam passes through an optical fiber including a core and cladding.
A reason therefor is that, when the fiber laser is used, power is easily adjusted merely by changing a length thereof. For example, when the length is set to a range of 10 mm to 300 mm, power in a wide range of 5 to 40 W is easily obtained. Further, the fiber laser is easily treated when compared to another gas laser, etc.
As an example, a type of the optical fiber is preferably set to a single mode having a collimator. Further, a diameter of the optical fiber is preferably set to a value within a range of 2 to 20 mm, and a length of the optical fiber is preferably set to a value within a range of 10 mm to 300 mm.
In addition, more preferably, the diameter of the optical fiber is set to a value within a range of 80 μm to 10 mm, and the length of the optical fiber is set to a value within a range of 10 cm to 5 m.
Besides, when the fiber laser is used, it is possible to continuously emit a long-wavelength laser, or to emit a pulse-type long-wavelength laser turned ON/OFF at a switching time of 10 to 500 μsec.
(2) Long-Wavelength Laser Irradiation Method
Next, a long-wavelength laser irradiation method will be described while mentioning
In more detail, the long-wavelength laser irradiation device 50 may be prepared above a support member 64, and the transparent plastic container 10 may be attached to a holder 60 in the perpendicular direction while the main plastic container body 12 is pressed against an inner wall of the cover portion 14, thereby finishing preparation.
Subsequently, only the welding-scheduled portion 12′ may be laser-welded using a pinpoint, and set as a laser welding portion by irradiating the transparent plastic container 10 from a side thereof with a long-wavelength laser having a predetermined wavelength of above or equal to 1.2 μm from the long-wavelength laser irradiation device 50, for example, a semiconductor laser device (also including the fiber laser) or a vertical-cavity surface-emitting laser (VCSEL) while rotating the transparent plastic container 10 attached to the holder 60 at 5 to 50 revolutions per minute (rpm) using a rotating motor 62.
Herein, when a voltage is applied, GaInNAsSb, InGaAsP/InP, GaInNAs/GaAs, erbium YAG, holmium YAG, etc. is suitable as a semiconductor material that oscillates a long-wavelength laser.
Further, in the case of the fiber laser, a semiconductor material containing a semiconductor material (glass material) as a main agent and a three-level element such as erbium, neodymium, ytterbium, etc. as a doping agent is suitable for a core portion that oscillates a long-wavelength laser.
For example, it has been confirmed that a long-wavelength laser having a wavelength of 1.55 μm may be obtained in the case of a semiconductor material doped with erbium.
Further, it has been confirmed that a long-wavelength laser having a wavelength of 1.08 μm may be obtained in the case of a semiconductor material doped with ytterbium.
In addition, in the case of the long-wavelength laser irradiation device 50, it is preferable to adjust a position of a laser irradiation unit 52 using an XY table 58 to which the long-wavelength laser irradiation device 50 is attached such that a focal position of a laser beam corresponds to a predetermined place, and to visually check a state of the laser beam and a state of an irradiation surface of the laser beam using a CCD camera 54 attached to a monitor/PC control device 56.
Therefore, as illustrated in
Meanwhile, as illustrated in
(3) Rotation Driving
In addition, as illustrated in
A reason therefor is that, when a long-wavelength laser is emitted while the transparent plastic container 10 is in a rotated state as described above, a laser beam is uniformly emitted, and a predetermined laser welding property may be obtained while effectively preventing occurrence of blistering or deformation in the laser welding portion.
More specifically, it is preferable to prepare the long-wavelength laser irradiation device 50 above the support member 64 illustrated in
(4) Light Condensing Property
In addition, when a long-wavelength laser is emitted, it is preferable to emit the long-wavelength laser through the condensing lens 20 illustrated in
A reason therefor is that, when a long-wavelength laser 50″ is emitted through the condensing lens 20, a laser absorbing property in a welding-scheduled portion corresponding to a laser welding portion may be controlled, and a predetermined laser welding property may be obtained while preventing occurrence of blistering or deformation.
More specifically, as illustrated in
Although not illustrated, it is preferable to fix the condensing lens 20 onto an operation table, and allow the operation table to move in a three-dimensional (3D) direction corresponding to XYZ directions in order to adjust a focal position, etc.
(5) Focal Position
In addition, as illustrated in
A reason therefor is that, when the focal position of the long-wavelength laser is considered, a laser absorbing property in the laser welding portion may be controlled, and a predetermined laser welding property may be obtained while preventing occurrence of blistering or deformation.
More specifically, as illustrated in
Hereinafter, the invention will be described in more detail using Examples. However, the invention below illustratively describes the invention, and the invention is not restricted to the description.
1. Production of Transparent Plastic Container
(1) Process (1)
EastarAN014 (manufactured by Eastman Chemical Company) corresponding to PCTA as a polyester resin was mixed using an injection molding device, and the cover portion 14 illustrated in
In more detail, an injection temperature of the injection molding device was set to 280° C., and an injection pressure thereof was set to 500 kgf/cm2 to manufacture the cover portion made of the transparent polyester resin (visible light transmittance in wavelength of 1.9 μm: 99%, laser absorption rate: 70%) illustrated in
In addition, similarly, the main plastic container body (external diameter: 44.5 mm, volume: 120 ml) illustrated in
In more detail, an injection temperature of the injection molding device was set to 280° C., and an injection pressure thereof was set to 500 kgf/cm2 to produce the main plastic container body made of a colored transparent polyester resin (visible light transmittance in wavelength of 1.9 μm: 99%, laser absorption rate: 70%) illustrated in
(2) Process (2)
Subsequently, the protrusion of the cover portion was irradiated with a long-wavelength laser beam in a predetermined condition through a portion of the inner wall of the main plastic container body using the laser irradiation device illustrated in
In more detail, as illustrated in
Subsequently, the transparent plastic container 10 was irradiated with a long-wavelength pulse laser beam (wavelength: 1.9 μm, laser power: 10 W) turned ON/OFF at an interval time of 100 μsec for 15 seconds from the laser irradiation unit 52 of the laser irradiation device 50 while being rotated at 12 rpm by the rotating motor 62. In other words, the transparent plastic container 10 was obtained using laser welding while the welding-scheduled portion 12′ was disposed to be positioned between the focal position (A) of the long-wavelength laser and the condensing lens 20.
In addition, in the case of the laser irradiation device 50, a position of the irradiation unit 52 was adjusted using the XY table 58 of the laser irradiation device 50 such that the focal position (A) of the long-wavelength laser beam is present behind the laser welding portion corresponding to the welding-scheduled portion 12′, and a state of the laser beam and a state of an irradiation surface of the laser beam was visually checked using the CCD camera 54 attached to the monitor/PC control device 56.
2. Evaluation of Transparent Plastic Container
(1) External Appearance
The laser welding portion (welding-scheduled portion) of the obtained transparent plastic container was visually observed, and an external appearance thereof was evaluated using a criterion below.
⊙ (Very good: VG): bubble or deformation is not observed at all
◯ (Good: G): bubbles or deformation is rarely observed
Δ (Fair: F): bubbles or deformation is slightly observed
x (Bad: B): a lot of bubbles or noticeable deformation is observed
(2) Laser Welding Property 1 (Leak Pressure)
Compressed air was inserted into the obtained transparent plastic container using a compressor such that a set pressure is obtained every 10 kPa, the set pressure is reached in 5 seconds, and the set pressure is maintained without change for 10 seconds until an internal pressure becomes 560 kPa.
In addition, the internal pressure obtained when a pressure difference between a pressure (pressure 1), which is obtained after 10 seconds from when a compressing valve led from the compressor is blocked, and a pressure (pressure 2), which is obtained after 30 seconds from when the compressing valve is blocked, becomes ±40 kPa was set to a leak pressure, and then a laser welding property was evaluated based on a criterion below.
⊙ (Very good: VG): leak pressure is above or equal to 500 kPa
◯ (Good: G): leak pressure is above or equal to 480 kPa
Δ (Fair: F): leak pressure is above or equal to 460 kPa
x (Bad: B): leak pressure is below 460 kPa
(3) Laser Welding Property 2 (Destructive Test)
Compressed air was inserted into the obtained transparent plastic container using the compressor such that the internal pressure changes from 100 kPa to 560 kPa, a pressure (maximum: 560 kPa) was measured until the laser welding portion was damaged, and then a laser welding property was evaluated based on a criterion below.
⊙ (Very good: VG): laser welding portion is not damaged even when pressure is above or equal to 560 kPa
◯ (Good: G): laser welding portion is not damaged even when pressure is above or equal to 500 kPa
Δ (Fair: F): laser welding portion is not damaged even when pressure is above or equal to 450 kPa
x (Bad: B): laser welding portion is damaged when pressure is below 450 kPa
In Example 2, a transparent plastic container was produced using laser welding similarly to Example 1 except that an irradiation time of the long-wavelength laser device was set to 10 seconds, and a laser welding property, etc. was evaluated. An obtained result is shown in Table 1.
In Example 3, a transparent plastic container was produced using laser welding similarly to Example 1 except that power of the laser device was set to 7 W, and an irradiation time was set to 15 seconds, and a laser welding property, etc. was evaluated. An obtained result is shown in Table 1.
In Example 4, a transparent plastic container was produced using laser welding similarly to Example 1 except that power of the laser device was set to 5 W, and an irradiation time was set to 15 seconds, and a laser welding property, etc. was evaluated. An obtained result is shown in Table 1.
In Examples 5 to 8, a plastic container was produced using laser welding similarly to Examples 1 to 4 except that a wavelength of an emitted long-wavelength laser was decreased to 1.2 μm or 1.4 μm from 1.9 μm, and laser power and an irradiation time were changed, and a laser welding property, etc. was evaluated. An obtained result is shown in Table 1.
In Comparative Example 1, a plastic container was produced using laser welding similarly to Example 1 except that carbon particles were mixed with the transparent polyester resin included in the cover portion such that the carbon particles correspond to 1 wt. % with respect to the whole amount, and a laser welding property, etc. was evaluated. An obtained result is shown in Table 1.
In Comparative Example 2, a plastic container was produced using laser welding similarly to Example 1 except that a wavelength of an emitted long-wavelength laser was decreased to 0.8 μm from 1.9 μm, and a laser welding property, etc. was evaluated. An obtained result is shown in Table 1.
In Comparative Example 3, a plastic container was produced using long-wavelength laser welding similarly to Example 1 except that a wavelength of an emitted long-wavelength laser was decreased to 0.2 μm from 1.9 μm, and a laser welding property, etc. was evaluated. An obtained result is shown in Table 1.
According to a transparent plastic container and a method for producing the same of the invention, even a combination of a plastic container/cover made of a transparent polyester resin may be stably laser-welded in a short time without mixing a significant quantity of a laser absorber by considering a wavelength, etc. of a laser to be used.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-166336 | Aug 2014 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2015/072014 | 8/4/2015 | WO | 00 |
