JP4060690B2 - Method for producing molded body for preventing cracking and whitening of surface pattern layer in heat-molded stretched part, plastic sheet for molding, plastic molded body - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a molded body that prevents cracking and whitening of a surface pattern layer in a thermoformed stretched part of a plastic molded body.
[0002]
[Problems to be solved by the invention]
When a resin is applied to the surface of the base sheet to form a surface pattern layer, and then the base sheet is thermoformed to form recesses, protrusions, etc. in the sheet surface, The surface texture layer (printed portion) may be cracked or whitened, resulting in a decrease in design properties.
[0003]
Therefore, the present invention is intended to provide a method for producing a molded body that prevents cracking and whitening of a surface pattern layer (particularly, a printing layer) in a thermoformed stretched part of a plastic molded body.
[0004]
[Prior art]
Although not directly related to the present invention, the following methods can be cited as conventional techniques worthy of reference.
[0005]
In Patent Document 1, printing ink containing phthalic acid diester is printed only on a specific portion of a base material, and further, an unsaturated polyester is applied, and a concave portion is formed in the printed portion by utilizing a repellency phenomenon between a printing portion and a resin component. A method of forming is disclosed.
[0006]
Patent Document 2 discloses that a paint surface having a different wettability with respect to an electron beam or a photocurable paint from the material surface is formed on the material surface in a pattern, and further an electron beam curable paint or an unsaturated polyester resin-based photocurable paint. A method is disclosed in which a wettable portion is depressed, a wettable portion is raised, and then an uneven surface formed by electron beam or light irradiation is cured as it is.
[0007]
Patent Document 3 discloses a printing coating in which an undercoat ink or a clear paint is applied on a material, and an overcoat paint made of an electron beam or an ultraviolet curable clear paint is applied on the undercoat ink or the clear paint. In the product, by setting the surface tension of the undercoat ink or the clear paint to be smaller than the surface tension of the top coat paint, the top coat paint is cured to form a concavo-convex pattern 55 on the portion where the ink or clear paint is applied. Disclosed is a method of forming a surface-finished printed coating.
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 48-58068 [Patent Document 2]
Japanese Patent Publication No. 51-26937 [Patent Document 3]
JP-A-6-278354
[Means for Solving the Problems]
The present invention includes a step of forming a surface pattern layer by laminating a resin on a substrate, and heat-molding a portion where the surface pattern layer is formed (for example, vacuum forming, pressure forming, pressure forming). In the method for producing a molded body, an overprint varnish (OP varnish) or a base forming resin containing a resin having better molding stretchability than OP varnish is laminated on at least a portion of the base material that is to be stretched during heat molding. By forming a base resin layer and laminating a pattern forming resin on the base resin layer in a planar view sea island shape to form a surface pattern layer (for example, a printing layer), The manufacturing method of the molded object characterized by preventing whitening is proposed.
[0010]
The present invention is also a plastic sheet for molding provided with a portion that is to be stretched during thermoforming (for example, vacuum forming, pressure forming, pressure vacuum forming, etc.), and at least on the base material that is to be stretched during heat forming. Overprint varnish (OP varnish) or a base resin containing a resin that has better molding stretch followability than OP varnish is formed to form a base resin layer, and the pattern forming resin is planarized on the base resin layer. Proposed are a plastic sheet for molding provided with a structure in which a surface pattern layer (for example, a printing layer) is formed by laminating in a visual sea island shape, and a plastic molded body formed by thermoforming the plastic sheet for molding.
[0011]
The molding plastic sheet having such a configuration is also an intermediate in the method for manufacturing the molded body, and can be suitably used for the method for manufacturing the molded body, such as vacuum, compressed air, or compressed air vacuum molding. Even if it heat-forms, the molded object provided with the surface pattern layer (for example, printing layer) without a crack and whitening can be provided.
[0012]
In the method for producing a molded body and the plastic sheet for molding according to the present invention, as a method of laminating a pattern forming resin on the base forming resin in a sea-view shape in plan view, a method utilizing a repelling phenomenon between the base forming resin and the pattern forming resin Adopting a method that uses the difference in surface tension between the base resin and the pattern resin, a method that uses ink mixed with the pattern resin, and a method that uses the difference in wettability between the base resin and the pattern resin Among them, a method using a difference in surface tension between the base forming resin and the pattern forming resin is preferable.
[0013]
As the pattern forming resin at this time, it is preferable to use a resin having a surface tension of about 10 μN / cm or more larger than that of the base forming resin. Above all, when such a pattern forming resin is applied to the above production method, it is a resin that can be laminated in the shape of a sea island in plan view when uniformly coated with a thickness of about 0.2 to 20 μm on the OP varnish surface. Is preferred.
[0014]
The term “stretching” in claims 1 and 4 does not particularly limit the stretching ratio, but when stretched to about 110% or more, the surface pattern layer is liable to crack or whiten, so about 110% or more. In particular, when the film is stretched to about 150% or more, the effects of the present invention can be further enjoyed.
In addition, the meaning of “including” in “·· underlying resin including a resin having more excellent mold stretching followability” in claims 1 and 4 includes at least 50% or more of such a resin as a main material, and mold stretching It means that other substances of the resin may be included as long as the followability is not impaired.
In the present invention, “molding / drawing followability” means a physical property indicating the degree of easiness of elongation when the substrate is stretched following molding and stretching, and the elongation (%) according to JIS K 7113 after coating. ) On the basis of.
In the present invention, “stacking the pattern-forming resin in the shape of a sea island in a plan view” means that a pattern unit having an appropriate size / appropriate shape is adjacent to a pattern unit so as not to form a pattern unit having a certain size or more. It means that they are independently arranged so as not to be connected to each other, and preferably includes the intention of independently arranging pattern units of arbitrary shapes having an area smaller than a square of about 1 mm × 1 mm.
The “molded body” in the present invention is a molded plastic sheet as an intermediate body (formed into a molded body when further molded by heating) by molding a plastic sheet for molding to form a recess or a projection in the sheet surface. Is also included.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
First, the structure and manufacturing method of the plastic sheet for molding will be described, and then the manufacturing method of a molded body using the same will be described.
[0016]
(Plastic sheet for molding)
As shown in FIGS. 1 and 2, the plastic sheet 10 for molding is formed on at least a portion 1A that is likely to be stretched at the time of heat molding of the base material 1A rather than overprint varnish (OP varnish) or OP varnish. The base resin layer 2 is formed by laminating a base forming resin containing a resin excellent in molding stretch followability, and the pattern forming resin is laminated on the base resin layer 2 in a sea island shape in plan view. The structure formed by forming is provided. Since it is “at least”, the surface pattern layer 3 is formed by laminating the base resin layer 2 on the entire surface of the base material 1 and laminating the pattern forming resin on the base resin layer 2 in the shape of a sea island in plan view. May be formed.
Further, the structure of the surface pattern layer 3 other than the portion that is planned to be stretched at the time of thermoforming or a portion that may possibly be stretched is arbitrary.
[0017]
For the substrate 1, various resin (plastic) sheets or films are preferably used. Among these, a transparent resin sheet or film is preferable in that it can provide a packaging material with high design properties.
[0018]
As the transparent resin sheet or film, for example, a sheet or film made of polylactic acid, polyethylene terephthalate, polypropylene, polyethylene, polyacrylic ester, polyether ketone, polyimide, polycarbonate, polysulfone, polystyrene, polyether or other amorphous resin is used. Can be mentioned. Of these, polyethylene terephthalate, polypropylene, polystyrene, and the like are preferable in consideration of moldability and folding resistance. Among them, polyethylene terephthalate (PET), for example, amorphous PET (“A-PET”) is particularly preferable in terms of transparency and rigidity. Is also preferred.).
[0019]
The surface of the base material 1 may be subjected to surface treatment such as frame treatment, corona discharge treatment, chemical treatment, primer treatment, etc., so as to enhance the adhesion of the base resin layer 2.
[0020]
The base resin layer 2 can be formed using OP varnish or a resin having better molding stretchability than OP varnish.
[0021]
Further, the surface tension of the base forming resin according to JIS K-6768 is preferably about 320 μN / cm or less, more preferably about 300 μN / cm or less. The lower limit at this time is actually about 200 μN / cm in the current technical level, but the lower limit is theoretically not determined.
In addition, the contact angle of the base forming resin is preferably about 70 to 90 °, and particularly preferably about 75 to 90 °.
[0022]
The type is not limited as long as it satisfies these conditions and can be attached to the substrate 1, and in addition to OP varnish, for example, acrylic acid and its ester, methacrylic acid and its ester, styrene, ethylene, Resin obtained by polymerizing at least one monomer such as vinyl acetate or vinyl chloride, chlorinated polypropylene resin, chlorinated rubber, saturated polyester resin alone or mixed with 2 to 4 kinds of toluene, xylene, ethyl acetate, methyl acetate, Resin (varnish) dissolved in a solvent such as npropyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, acetone, xylene, methyl acetate, isopropyl alcohol, ethanol, etc., or a resin dissolved or dispersed in water or alcohol alone or in a mixed solvent (Varnish) with hydrocarbon compounds, silicone compounds, Oil repellent, such as silicon compound or the like can be used resin was added.
It should be noted that other substances may be included as long as molding stretchability is not impaired.
[0023]
The thickness of the base resin layer 2 is not particularly limited, but is preferably about 0.2 to 20 μm from the viewpoint of mold drawing followability.
[0024]
As shown in FIG. 1, the surface pattern layer 3 is not connected to the adjacent pattern units 3A and 3A so that the pattern unit 3A having an appropriate size and shape is not connected to each other so that a pattern unit having a predetermined size or more does not occur. It forms in the shape of a sea island in plan view.
At this time, the size of the pattern unit 3A is preferably smaller than the square of about 1 mm × 1 mm. If the pattern unit 3A has this size, it is possible to prevent the surface pattern layer 3 from being cracked or whitened even if it is stretched to about 150% or more during heat molding.
[0025]
The pattern forming resin constituting the surface pattern layer 3 is a resin having a surface tension according to JIS K-6768 of about 10 μN / cm or more, particularly about 20 μN / cm or more, especially about 40 μN / cm or more, greater than that of the base forming resin. Is preferred. The upper limit at this time is actually about 400 μN / cm in the current technical level, but the upper limit is theoretically not determined.
If it is a pattern-forming resin having such a surface tension, the pattern-forming resin is laminated on the base resin layer 2 in the shape of a sea island in plan view simply by coating the base resin layer 2 uniformly. be able to.
The absolute value of the surface tension of the pattern forming resin is not particularly limited, but the surface tension according to JIS K-6768 is preferably about 240 μN / cm or more, and more preferably about 300 μN / cm or more. The upper limit at this time is actually about 200 μN / cm as the lower limit in the current technical level, but theoretically does not determine the upper limit.
The surface tension can be adjusted by using a surface conditioner such as silicon or acrylic.
Further, the contact angle of the pattern forming resin is preferably about 10 to 85 °, and particularly preferably about 30 to 80 °.
[0026]
The pattern forming resin may have any of the above physical properties, but from the viewpoint of production efficiency, an energy ray curable resin, that is, an electromagnetic wave or charged particle beam having an energy quantum capable of polymerizing or crosslinking molecules, for example, Resins that can be cured by irradiation with visible light, ultraviolet light (near ultraviolet light, vacuum ultraviolet light, etc.) X-rays, electron beams, ion beams, and the like can be preferably used.
[0027]
The thickness of the surface pattern layer 3 is not particularly limited, but is preferably about 0.2 to 20 μm.
[0028]
(Manufacturing method of plastic sheet for molding)
First, the base resin layer 2 is formed by applying a base forming resin uniformly at an appropriate thickness on the surface of at least a portion 1A (or the entire surface) to be stretched at the time of thermoforming of the base material 1.
Next, the pattern forming resin is applied almost uniformly on the base resin layer 2 with a thickness of about 0.2 to 20 μm, and after a predetermined time has elapsed, the pattern forming resin is cured as necessary to form the surface pattern layer 3. To do. At this time, the pattern forming resin moves and gathers naturally at appropriate intervals, and a plurality of pattern units 3A can be dispersed in the shape of sea islands in plan view. That is, a plurality of pattern units 3A having an appropriate size and an appropriate shape can be in an independently dispersed state with an appropriate interval from the adjacent pattern unit 3A. The base resin layer 2 is exposed between the adjacent pattern units 3A and 3A.
[0029]
As a method of laminating the base resin layer 2 on the substrate 1, various methods such as a method of applying the base forming resin can be adopted, but a method of applying the base forming resin is preferable. Specifically, gravure coat, gravure reverse coat, gravure offset coat, Mayer bar coat, air knife coat, spinner coat, roll coat, reverse roll coat, kiss coat, wheeler coat, silk screen solid coat, flow coat, spray coat, etc. The known coating means can be used, and among these, a method of coating a resin using a roll having a transfer portion having a predetermined shape is suitable.
[0030]
Moreover, as a method of applying the pattern forming resin, the methods mentioned as the coating method of the base forming resin can be employed.
The pattern forming resin is preferably applied to a thickness of about 0.2 to 20 μm, particularly about 0.5 to 10 μm. Even if it is less than about 0.2 μm or more than about 20 μm, it is difficult to disperse the pattern units 3A in a plan view sea-island shape simply by applying the pattern-forming resin almost uniformly.
[0031]
The pattern forming resin may be applied after the base forming resin is sufficiently dried, or may be applied before drying.
In order for the pattern-forming resin to move naturally and gather for each pattern unit, warm the pattern-forming resin or increase the time until irradiation with ultraviolet rays as much as possible, that is, a part of the pattern-forming resin. It is preferable to irradiate with ultraviolet rays after a period of natural movement.
[0032]
The pattern-forming resin curing treatment to be performed as necessary is performed by using an apparatus capable of irradiating energy rays such as ultraviolet rays and γ rays when an energy ray-curable resin is used as the pattern-forming resin. Good.
[0033]
When the surface pattern layer 3 is formed by such a method, the base resin layer 2 is laminated on the base material 1, and the pattern forming resin is applied almost uniformly on the base resin layer 2. If necessary, the pattern forming resin curing treatment is performed. By simply performing the process, the pattern-forming resin naturally gathers for each pattern unit, and can be made into a sea island shape in plan view.
[0034]
(Method for producing molded body)
The molded plastic sheet 10 can be manufactured by subjecting it to heat forming such as vacuum forming, pressure forming, or pressure forming.
At this time, even if there is a portion that is stretched to 150% or more, since it is formed as described above, the surface pattern layer 3 of the molded stretched portion is not cracked or whitened.
At this time, any currently known method can be adopted as the heat forming method.
[0035]
【Example】
OP varnish (OP varnish containing acrylic acid prepolymer and acrylic acid oligomer) on the entire surface of amorphous PET (“A-PET” haze 0.8%) with a thickness of 0.3 mm as a base-forming resin; Dainippon Ink & Chemicals, Inc. Manufactured by Dicure RT-8, JIS K-6768 with a surface tension of 300 μN / cm or less and a contact angle of 85 ° with a thickness of 1 μm, and UV curable resin ink (acrylic acid prepolymer and acrylic acid oligomer) on the entire surface. Ultraviolet curable resin ink contained: Dai Nippon Ink Chemical Co., Ltd. Dicure Clear UV-1601EM, surface tension 340 μN / cm according to JIS K-6768, contact angle 74 °) was applied almost uniformly to a thickness of 3 μm, and 20 mm SEC after coating. Thereafter, ultraviolet rays were irradiated with an ultraviolet irradiation device to obtain a plastic sheet for molding.
[0036]
On the surface of the obtained plastic sheet for molding, as shown in FIG. 1, a plurality of circular or oval pattern units 3A having a diameter of about 0.3 mm are dispersed at intervals of about 0.1 to 0.2 mm in the front, rear, left and right directions. And it became a sea island shape in plan view.
[0037]
The molding plastic sheet was thermoformed at 120 ° C. with a thermoforming machine, and a recess having a width of 20 mm, a length of 60 mm, and a depth of 10 mm was formed in the sheet surface to obtain a molded plastic sheet.
Thereafter, although observed over time, no cracking or whitening occurred on the surface of the base resin layer of the molded stretched portion.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a part of an example of a plastic sheet for molding according to an embodiment of the present invention.
2 is a cross-sectional view of a part of the molding plastic sheet of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Base material 2 Base resin layer 3 Surface pattern layer 3A Pattern unit 10 Plastic sheet for shaping | molding

Claims (7)

In a method for producing a molded body comprising a step of forming a surface pattern layer by laminating a resin on a base material, and thermoforming the portion on which the surface pattern layer is formed, at least a base of a portion to be stretched during thermoforming Overprint varnish (OP varnish) or a base forming resin containing a resin having better molding stretch followability than OP varnish is laminated on the material to form a base resin layer, and the pattern forming resin is formed on the base resin layer. A method for producing a molded body characterized by preventing the cracking and whitening of the surface pattern layer in the thermoformed stretched part by forming a surface pattern layer by laminating in the shape of a sea island in plan view. Laminating a pattern-forming resin in the shape of a sea island in a plan view means that each pattern unit is independently connected so that adjacent pattern units are not connected to each other in a circular or oval pattern unit having a smaller area than a 1 mm × 1 mm square. The method for producing a molded body according to claim 1, wherein the molding is arranged. The pattern-forming resin has a surface tension of 10 μN / cm or more larger than that of the base-forming resin, and has a thickness of 0 . The method for producing a molded body according to claim 1, which is a resin that can be laminated in a planar view sea-island shape when uniformly coated at 2 to 20 μm. A plastic sheet for molding with a portion that is to be stretched during heat molding, and at least on the base material of the portion that is to be stretched during heat molding, and more conformable to stretch and stretch than overprint varnish (OP varnish) or OP varnish A structure in which a base resin layer including an excellent resin is laminated to form a base resin layer, and a surface pattern layer is formed on the base resin layer by laminating a pattern forming resin in a plan view sea island shape. Plastic sheet for molding. Laminating a pattern-forming resin in the shape of a sea island in a plan view means that each pattern unit is independently connected so that adjacent pattern units are not connected to each other in a circular or oval pattern unit having a smaller area than a 1 mm × 1 mm square. The plastic sheet for molding according to claim 4, wherein the plastic sheet is arranged. The plastic sheet for molding according to claim 4 or 5, wherein the pattern forming resin is a resin having a surface tension of 10 µN / cm or more larger than that of the base forming resin. A plastic molded body obtained by heat-molding the plastic sheet for molding according to any one of claims 4 to 6.

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