JP2001002126A - Window pasting case - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the automatic case manufacturing adaptability by opening a window pasting case of a laminate formed of a paper and an oriented film composed of a polylactic polymer, having the shrinkage factor at a specified temperature/specified min. in a specified range and the haze of a specified percentage or less and providing a window seeing through the interior of the case. SOLUTION: A window 3 is so opened as to see through a content inside on a paper packaging case for packaging a commodity or the like, and a film is pasted on the window. The whole surface laminate 2 is composed of a polylactic polymer and formed of a laminate formed of a paper and an oriented film having the 0.5-5% shrinkage factor at 80 deg.C/10 min. and 10% or less haze, and provided with the window 3 seeing through the interior of the case. As the shrinkage factor is in the range of 0.5-5%, the film is made to shrink slightly when being laminated to form a window pasting case with a film section stuck on the window and free from the generation of looseness, surge and creases, and the automatic manufacturing adaptability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to window boxes, and more particularly to a biodegradable window box.

[0002]

2. Description of the Related Art At present, a box with a window is often used so that goods in the box can be seen. In a box with an empty window, the product inside may get dirty, and depending on the shape of the product, the product may come out of the box through the window. Boxes are used. Paper has the problems of low water resistance, oil and grease resistance, tear strength, etc.To solve those problems, the window sticking box should not be made of plastic material only for the window, It is common to compound a plastic material over the entire paper box.

[0003] As a plastic material, polypropylene is generally used, but a window-attached box obtained by combining a polypropylene film and paper is not suitable for an automatic box making machine (a folded box does not stand with an automatic box making machine). Therefore, they were assembled by hand. Furthermore, when manufacturing a window box using these plastic materials, when the window part after pasting on paper is observed, it shows wavy, loose, wrinkles, etc., which is not good in terms of finish. It was difficult. In addition, since a plastic material generally remains without being decomposed in a natural environment, there has been a problem that a composite window box does not have a natural collapse property.

On the other hand, biodegradable plastics, which are decomposed when left in a natural environment as plastic materials, have been receiving attention in recent years. One of them is a polylactic acid-based plastic material. As a composite of a polylactic acid-based material and paper, a base material containing vegetable fibers coated with polylactic acid or a derivative thereof (JP-A-4-334448), a copolymer of polylactic acid or lactic acid and oxycarboxylic acid A decomposable laminated paper composed of paper and a thermoplastic decomposable polymer whose main component is (JP-A-4-336246) is being studied. Further, a laminate obtained by laminating a specific oriented polylactic acid-based film and paper (Japanese Patent Laid-Open No. 8-252895) and the like have been studied. However, JP-A-4-334448, JP-A-4-33
Since the film used in No. 6246 is brittle, there is a problem that the portion attached to the window is easily broken. Furthermore,
The film described in 8-252895 has improved brittleness and exhibits good characteristics with respect to lamination properties with paper, but does not disclose the characteristics in manufacturing a window box, and does not disclose a window. It is not easy to suppress the occurrence of looseness, wrinkles, undulations, and the like in the portion, that is, the portion not in contact with the paper, and to achieve a clean finish.

[0005]

SUMMARY OF THE INVENTION A window box having good suitability for an automatic box making machine, free from looseness, wrinkles, waving, etc. of a portion stuck on a window, having a good finish, and having decomposability in a natural environment. Was sought.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, have completed the present invention. That is, the gist of the present invention is that a polylactic acid-based polymer has a shrinkage rate of 0.5 to 5% at 80 ° C./10 min.
And a stretched film (A) having a haze of 10% or less.
And a paper (B) laminated body, and the inside of the box is a window-attached box having a transparent window. As a preferred embodiment of the present invention, the above window-attached box wherein the average roughness Ra of the surface of the stretched film (A) is more than 0.01 and 0.08 or less;
The above-mentioned window box and the stretched film (A) in which at least one surface of the stretched film (A) is corona-treated.
The window box above, where both surfaces are corona treated
The surface wettability index of the stretched film (A) is 40 to 55 dyn
/ Cm, and the above-mentioned window box obtained by laminating the stretched film (A) and the paper (B) at 60 to 80 ° C.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

FIGS. 1 and 2 show a window-adhered box according to the present invention.
And, as in the example shown in FIG. 3, in a paper packaging box of a product or the like, a window is opened so that the contents can be seen through,
It takes a form in which a film is stuck on it. The size and number of the windows are not particularly limited, and the positions of the windows may be within one surface of the box, or may be over two, three, or four adjacent surfaces.

The polylactic acid-based polymer used in the present invention is a polymer containing L-, D- or DL-lactic acid units as a main component, and contains other hydroxycarboxylic acid units as a small copolymerization component. And may contain small amounts of chain extender residues.

As the polymerization method, known methods such as a condensation polymerization method and a ring-opening polymerization method can be employed. For example, in the polycondensation method, polylactic acid having an arbitrary composition can be obtained by directly dehydrating polycondensation of L-lactic acid or D-lactic acid or a mixture thereof.

In the ring-opening polymerization method (lactide method), lactide, which is a cyclic dimer of lactic acid, is obtained by using a selected catalyst while using a polymerization regulator or the like as necessary to obtain polylactic acid. be able to.

The preferred range of the weight average molecular weight of the polylactic acid polymer used in the present invention is 60,000 to 70.
10,000, more preferably 80,000 to 400,000, particularly preferably 100,000 to 300,000. If the molecular weight is too small, practical physical properties such as mechanical properties and heat resistance are hardly exhibited, and if it is too large, the melt viscosity is too high and molding processability is poor.

The monomers copolymerized with polylactic acid include optical isomers of lactic acid (D-lactic acid for L-lactic acid and L-lactic acid for D-lactic acid), glycolic acid,
3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-methyllactic acid, 2-hydroxycaproic acid and the like Lactones such as bifunctional aliphatic hydroxycarboxylic acid, caprolactone, butyrolactone, and valerolactone are exemplified.

For the purpose of adjusting various physical properties, heat stabilizers, light stabilizers, light absorbers, lubricants, plasticizers, inorganic fillers, coloring agents,
Pigments and the like can be added.

The stretched film includes a uniaxially stretched film and a biaxially stretched film, and the latter is preferred from the viewpoint of physical properties and the like.

In the production of a uniaxially stretched film, there are a stretching in a longitudinal direction only by a roll method and a stretching in a lateral direction only by a tenter method.

In the production of a biaxially stretched film, a sequential biaxial stretching method in which longitudinal stretching is performed by a roll method and a transverse stretching is performed by a tenter method, and a simultaneous biaxial stretching method in which longitudinal and horizontal stretching are simultaneously performed by a tenter are common.

The stretching conditions are 1.5 to 6 in the longitudinal direction.
And 1.5 to 6 times in the horizontal direction. In particular, from the viewpoint of the strength of the film and the thickness accuracy, it is preferably at least 3 times for uniaxial stretching and at least 2 times for longitudinal and transverse stretching in biaxial stretching. It is preferable that the ratio be 0.5 times or more.

In the uniaxial stretching method, the stretching temperature is 70 to 9
At 0 ° C., in the sequential biaxial stretching method, the longitudinal stretching temperature is 70 ° C.
It is preferable that the stretching temperature is in the range of 70 to 80 ° C in the sense that the simultaneous biaxial stretching method is included in the sequential biaxial stretching method. Stretching is preferred. When the stretching ratio and the stretching temperature are not in the above ranges, the thickness accuracy of the obtained film is remarkably reduced, and this tendency is particularly remarkable in a film which is heat-treated after stretching. Such thickness fluctuations, when printing a film, or laminating with another film or metal thin film, paper, or even in secondary processing such as bag making, cause a bad appearance of a product such as wrinkles and undulations. It becomes such a factor.

In the present invention, it is important to control the shrinkage of the film. That is, the preferable shrinkage ratio is 0.5 to 5% at 80 ° C./10 minutes. If the shrinkage is too low, after lamination with paper with a hole that becomes a window, observing the window part, the film shows
Loose, wavy, wrinkled, etc., and cannot be finished cleanly. If the temperature is too high, the heat applied at the time of lamination causes the film to shrink significantly, causing wrinkles and curling of the laminate with the laminated paper. When the shrinkage ratio is in the above range, the film slightly shrinks during lamination, and a window-attached box having a good finish without looseness, waving, and wrinkles of a portion of the film stuck to the window. More preferable shrinkage rate is 80 ° C./10 min.
Is 1 to 3%.

In lamination between a film and paper, it is important to have good slippage in consideration of the suppression of the generation of static electricity in the process and the finish without wrinkles. In order to improve the slip of the film, the method of applying a wax-like substance to the film surface is the simplest method, but this is not a preferable method because it reduces the adhesive strength between the film and the paper. The second method is a method in which inert inorganic particles are mixed into a polylactic acid-based polymer, and are projected on the film surface in a stretching process to roughen the surface. Thereby, the contact area between films or paper or the like is reduced, and the slip is improved. As a measure of the roughness, JIS
It is measured by the method described in B0601. Specifically, the average roughness Ra is more than 0.01 and 0.08 or less. If the average roughness Ra is too small, the surface of the film is not substantially roughened, the coefficient of friction increases, and the slipperiness is low. Conversely, if the average roughness Ra is too large, the scattering of light on the film surface will increase, and the transparency will decrease. In terms of transparency, the object of the present invention is a window-attached box through which the contents can be seen through, and the haze is preferably 10% or less, preferably 5% or less. A film having a haze of more than 10% allows the contents to be seen through, but does not remove the cloudiness and lacks sharpness.

In order to suppress the thermal shrinkage of the film, it is necessary to perform a heat treatment while holding the film. Normally, in the roll method, the film is stretched and then heat-treated by contacting with a heating roll. In the tenter method, the film is stretched in a state where the film is gripped by a clip, so that the film is immediately heat-treated. Although the heat treatment temperature depends on the melting point of the polylactic acid-based polymer to be used, heat treatment is performed at 110 to (melting point −10) ° C. for 3 seconds or more. Below this range, the heat shrinkage of the resulting film is high, and problems such as shrinkage of the film during processing are likely to occur in the film laminating process described above.
When the heat treatment temperature is (melting point−10) ° C. or higher, the surface of the film becomes significantly rough during the heat treatment, and the film is whitened and the transparency is impaired. Above the melting point, the film melts and breaks.

The stretched film (A) used in the present invention
Is, in view of out clearly corner of the box, it is preferable that the elastic modulus is 200 to 500 kgf / mm ^2, more preferably 250~450kgf / mm ^2. To make the corners of the box clear, as shown in Fig. 3, when the laminate with paper is folded in the form of a box, where the window spans the two sides of the box, the film itself will be squared. . It says that the horn is neatly folded and becomes a line. With a flexible film, squaring cannot be performed, and bumps and undulations are observed in this area. This concerns the self-support of the film.

The stretched film (A) used in the present invention
Is preferably corona-treated before being combined with paper.
By performing the corona treatment, the wettability of the film surface can be improved, and the adhesive force after applying the adhesive and bonding to the paper can be improved. A film without corona treatment will peel off the paper with a slight force. The corona treatment can be used with a conventionally known device. The surface of the film to be corona treated is the surface used for lamination with paper. However, the laminated body bonded to the paper is punched into a mold as shown in a development view of FIG. The inside of the paper and the margin portion are connected by applying or dipping an adhesive to a margin as shown in the figure so as to wrap the laminate as shown in the developed view. This margin is the opposite side of the film pasted to the paper. Therefore, since the adhesive is applied on the film, if an external force is applied even once pasted, for example, in a state where the product is put in a box, the film and the adhesive can be easily applied by the impact of an accidental drop. Separation at the interface with the metal may occur. Therefore, if stronger adhesion is desired, it is preferable to improve the wettability on this surface, and it is better to perform corona treatment.

The stretched film (A) used in the present invention has a surface wetting index of 4 from the viewpoint of the above adhesiveness.
It is preferably from 0 to 55 dyn / cm. More preferably, it is 45 to 55 dyn / cm.

The paper (B) in the present invention is not particularly limited, and examples thereof include kraft paper, printing paper, imitation paper, and paperboard.

The stretched film (A) in the present invention can be laminated with the paper (B) by a known method such as dry lamination, wet lamination or hot melt lamination. As described above, it is preferable to laminate at 60 to 80 ° C. from the viewpoint of enhancing the beauty of the film in the window-attached portion. If the temperature during lamination is too low, shrinkage of the film will not be obtained, and if the temperature during lamination is too high, the shrinkage will be too high.

The stretched film (A) may be bonded to the paper (B) with an adhesive or a pressure-sensitive adhesive. Examples of adhesives and pressure-sensitive adhesives to be used include vinyl-based, acrylic-based, polyamide-based, rubber-based, urethane-based, and biodegradable substances. The amount of the adhesive and pressure-sensitive adhesive used is very small when viewed from the entire window box, but it is preferable that these are also biodegradable. Examples of biodegradable ones include carbohydrates such as starch, proteins such as glue, gelatin and casein, and unvulcanized natural rubber.

The layer structure of the window box material of the present invention has a two-layer structure of stretched film (A) / paper (B) and a three-layer structure of stretched film (A) / paper (B) / stretched film (A). Although a structure etc. are mentioned, it is not specifically limited.

The laminate consisting of the laminated film and paper is punched out, for example, as shown in the exploded view shown in FIG. 1, and then boxed by an automatic box making machine or manually. In the use of the automatic box making machine, an adhesive is applied to a margin from the developed view shown in FIG. 1 and bonded to form a two-fold state as shown in FIG. 4, and then the upper and lower sides are sucked as shown in FIG. Standing and filling the contents. However, the suitability for automatic box production differs depending on the condition of the standing leg, and the angle θ shown in FIG.
If it is close to °, it will be in a favorable state. The standard for suitability for automatic box making is 20 ° or less, preferably 10 ° or less.

[0031]

The present invention is not limited by the following examples. The measurement and evaluation shown in the examples were performed under the following conditions.

Evaluation method (1) Melting point Using Perkin Elmer DSC-7, JIS-K71
The melting point was measured based on 21. That is, after conditioning 10 mg of a test piece from a film in a standard state, an endothermic peak was obtained from a DSC curve drawn while the temperature was raised to 200 ° C. at a nitrogen gas flow rate of 25 ml / min and a heating temperature of 10 ° C./min. Was read, and the temperature at that time was taken as the melting point.

(2) Heat Shrinkage A film sample was cut out in the longitudinal direction (MD) and in the direction perpendicular to the direction (TD) into 140 mm (width 10 mm), and a surface line of 100 mm was inserted between the cut pieces. After immersion for 5 minutes, the dimension between the evaluation lines was measured, and the heat shrinkage was calculated according to the following equation 1.

[0034]

(Equation 1) (3) Haze Measured according to JIS K7105. The smaller the value, the higher the transparency.

(4) Surface Roughness The measurement was performed based on the method described in JIS B0601. Kosaka Laboratory Co., Ltd.
-3F), the center line average roughness Ra and the ten-point average roughness (Rz) were determined. The stylus tip radius of the measuring instrument was 2 μm, the load was 30 mg, the measurement length was 8 mm, and the cutoff value was 0.08 mm.

(5) Surface Wetting Index Measurement was carried out in accordance with JIS K 6788.

(Sending Materials) (6) Suitability for Laminating The adhesive was uniformly applied to A3 size cardboard having small windows at predetermined positions, and then the film cut into A3 was pressed with a manual roller. The adhesive used was Takerac A-991 / Takenate A-19 (mixed at a ratio of 15/1) (manufactured by Takeda Pharmaceutical Co., Ltd.). Immediately, the laminate was kept in an oven at 60 ° C. for 1 minute and dried. Thereafter, the appearance of the film and the adhesive strength between the paper and the film were observed. Those with wrinkles due to shrinkage, those with curling of the laminate, and those that easily peeled were marked with x, and those without were marked with o.

(7) Finishing of the window-attached part After the evaluation of (6), the window-attached part was observed,
Those with undulations and wrinkles were marked with x, and those without were marked with ○.

(8) Suitability for automatic box making The laminated body prepared in (6) and aged at 38 ° C. for 48 hours or more was punched out as shown in the developed view of FIG. And folded in two. The adhesive used was the same as that used in (6), and was aged at 38 ° C. for 48 hours or more. Then, as shown in FIG. 6, the user raises and lowers the hand, stands up, and then crushes it over a square as shown in FIG. Then, the standing condition of the box when no load is applied is changed by the angle θ as shown in FIG.
Was measured and evaluated. When this numerical value was 20 ° or less, it was expressed as ○ in a good state, and otherwise, as x.

(9) Drop Test A log weighing 150 g was placed in the box prepared in (8) and sealed. This was dropped on a concrete floor from a height of 1 m. Observation was made of the deformation of the box due to the impact after dropping, especially the bonded part. A sample where complete peeling was observed at the marginal portion was indicated by x, a case where the connection was slightly stopped was indicated by Δ, and a sample with almost no abnormality was indicated by ○.

Example 1 Polylactic acid having a molecular weight of about 200,000 and having a ratio of L-lactic acid component to D-lactic acid component of 95: 5, and granular dioxide having an average particle size of about 2.5 μm manufactured by Fuji Silysia Chemical Ltd. Silicon (silica)
(Product name: Sylysia 430) After drying 1 part by weight of each to remove water sufficiently, it is put into a Φ40 mm co-axial twin screw extruder, set to about 200 ° C., melt-mixed, extruded into strands and extruded. The mixture was cut into pellets while cooling. The pellets were used as a master batch, dried again, and mixed with 10% of the above-mentioned polylactic acid, which was dried again.
Put into a 40 mm co-rotating twin screw extruder and set temperature 210 ° C
Then, the mixture was extruded into a sheet and quenched and solidified by a rotating cooling drum to obtain a substantially amorphous sheet. The obtained sheet is heated in combination with an infrared heater while being in contact with a hot water circulating roll, and is heated at 75 ° C. in the longitudinal direction between the peripheral speed difference rolls.
0 times, and then guided the stretched sheet to a tenter while holding the clip with a clip, and set at 75 ° C. in the vertical direction of the film flow.
After stretching 3.0 times, it was heat-treated at 120 ° C. for about 15 seconds to produce a film having a thickness of 15 μm.

The obtained film was subjected to a surface treatment in air so as to have a wetting index shown in Table 1 with a corona treatment machine as required. As shown in Table 1, the corona treatment on the surface was performed on both surfaces and performed only on one surface.

Example 2, Comparative Examples 2 to 5 Films shown in Table 1 were produced in the same manner as in Example 1.

In Comparative Example 2, the average particle size of the granular silicon dioxide (silica) was 6.0 μm (Fuji Silysia Chemical Ltd.)
(Trade name: Sylysia 770).

Example 3 Polylactic acid having a molecular weight of about 220,000 and having a ratio of L-lactic acid component to D-lactic acid component of 98: 2, and granular dioxide having an average particle size of about 2.5 μm manufactured by Fuji Silysia Chemical Ltd. Silicon (silica)
(Product name: Sylysia 430) After drying 1 part by weight of each to remove water sufficiently, it is put into a Φ40 mm co-axial twin screw extruder, set to about 200 ° C., melt-mixed, extruded into strands and extruded. The mixture was cut into pellets while cooling. The pellets were used as a master batch, dried again, and mixed with 10% of the above-mentioned polylactic acid, which was dried again.
Put into a 40 mm co-rotating twin screw extruder and set temperature 210 ° C
Then, the mixture was extruded into a sheet and quenched and solidified by a rotating cooling drum to obtain a substantially amorphous sheet. The obtained sheet was heated together with an infrared heater while being in contact with a hot water circulation type roll, and was heated at 77 ° C. in the longitudinal direction between peripheral speed difference rolls.
6 times, and then guide the longitudinally stretched sheet to a tenter while holding it with a clip.
After stretching 2.8 times, the film was heat-treated at 135 ° C. for about 15 seconds to produce a film having a thickness of 15 μm.

Comparative Example 1 A film shown in Table 1 was produced in the same manner as in Example 3.

[0047]

[Table 1]

[0048]

According to the present invention, the suitability for an automatic box making machine is good,
It is possible to provide a window-attached box that is free from looseness, wrinkles, and undulations in a portion attached to a window, has a good finish, and is decomposable in a natural environment.

[Brief description of the drawings]

FIG. 1 is a development view of a window box.

FIG. 2 is a view of a window box assembled from the developed view of FIG. 1;

FIG. 3 is a view of a window-attached box in which a window covers two sides of the box.

FIG. 4 is a view in which the developed view of FIG. 1 is punched out, an adhesive is applied to a glue, and the two are folded together.

FIG. 5 is a diagram in which the two-folded state shown in FIG. 4 is sucked up and down to stand and fill the contents.

FIG. 6 is a diagram showing an experiment method for suitability for automatic box making.

[Explanation of symbols]

 1 Glue 2 Laminate (Film) 3 Window (Film) 4 Suction direction 5 Raise direction 6 Load direction

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B29C 55/02 B29C 55/02 B29K 67:00 B29L 22:00 F-term (Reference) 3E067 BA06A BB01A BB14A BB18A BB25A BC06A CA11 CA23 CA30 EE20 4F100 AA20H AK41A BA02 BA03 BA06 CA19 CA23 DD07 DG10B EJ37A EJ55A GB16 JA03A JB04A JC00 JK15A JN01A YY00A 4F210 AA24 AC03 AD06 Q08 AQ03 Q01 Q03 A03Q01 Q03 A AD08 AD32 AG01 AG03 AH56 SA07 SC06 SC07 SD01 SD17 SG01 SH06 SH24 SJ31 SN02

Claims (6)

[Claims] 1. A polylactic acid-based polymer at 80 ° C./1
A window-attached box comprising a laminate of a stretched film (A) and paper (B) having a shrinkage of 0.5 to 5% at 0 min and a haze of 10% or less, and having a transparent window inside the box. . 2. The average roughness R of the surface of the stretched film (A)
The window-attached box according to claim 1, wherein a is more than 0.01 and not more than 0.08. 3. The window-attached box according to claim 1, wherein at least one surface of the stretched film (A) is corona-treated. 4. The window-attached box according to claim 1, wherein both surfaces of the stretched film (A) are corona-treated. 5. The stretched film (A) has a surface wetting index of 4
2. The pressure is 0 to 55 dyn / cm.
The window-attached box according to any one of Items 1 to 4. 6. The stretched film (A) and the paper (B) are
2. The laminate according to claim 1, wherein the laminate is formed at a temperature of from about 80.degree.
6. The window-attached box according to any one of items 1 to 5.