JP2003118726A - Window-adhered box - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a window-adhered box which is well adapted for an automatic box making machine, has no baggy state, wrinkle and corrugation or the like at a portion adhered to its window part, shows a superior finished state and has a decomposing property in the natural environment. SOLUTION: This window-adhered box is comprised of a laminated member of a drawn film (A) made of a polymer of a polylactic acid type with a shrinkage rate of 0.5 to 5% at 80 deg.C/10 min and a haze of 10% or less and a paper (B), and this window-adhered box has a window through which an inside part of the box can be seen.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a window-coated box, and more particularly to a biodegradable window-mounted box.

[0002]

2. Description of the Related Art At present, boxes with windows are often used so that the products in the boxes can be seen. The product inside may be dirty in a box with only empty windows, or the product may go out of the box depending on the shape of the product.Therefore, a plastic material such as polypropylene is applied to the window part to attach the window. Boxes are used. Paper has the problems of low water resistance, oil and fat resistance, tear strength, etc., so in order to solve these problems, window pasting boxes do not use plastic materials only for the window part, but open windows It is common to combine a plastic material in the entire paper box.

Polypropylene is generally used as a plastic material, but a window box made of a composite of polypropylene film and paper is not suitable for an automatic box making machine (a folded box does not stand up in an automatic box making machine). Therefore, it was assembled by hand. Furthermore, when manufacturing a window box using these plastic materials, when observing the window part after sticking it on paper, waviness, looseness, wrinkles, etc. were seen, and it is said that it is good in terms of finish. It was difficult. Further, since the plastic material generally remains without being decomposed in the natural environment, there is a problem that the composite window sticking box does not have a natural disintegration property.

On the other hand, biodegradable plastics, which are decomposed when left in a natural environment as a plastic material, have been attracting attention in recent years. One of them is a polylactic acid type plastic material. As a composite of a polylactic acid-based material and paper, a base material containing plant fibers coated with polylactic acid or a derivative thereof (Japanese Patent Laid-Open No. 4-334448)
No. 4), degradable laminated paper composed of paper and a thermoplastic degradable polymer containing polylactic acid or a copolymer of lactic acid and oxycarboxylic acid as main components (JP-A-4-336246). In addition, a laminate of a specific oriented polylactic acid-based film and paper (Japanese Patent Application Laid-Open No. 8-252895).
No.) etc. are being considered. However, the above-mentioned JP-A-4
Since the films used in JP-A-334448 and JP-A-4-336246 are brittle, there is a problem that the portion attached to the window is easily broken. Further, JP-A-8-25289
The film described in No. 5 has improved brittleness and exhibits good characteristics for laminating with paper,
It does not disclose the characteristics of manufacturing a window-attached box, and it is not easy to finish it cleanly by suppressing the occurrence of looseness, wrinkles, waviness, etc. in the window portion, that is, the portion that does not come into contact with the paper.

[0005]

A window sticking box which has good suitability for an automatic box making machine, is free from dangling, wrinkling, waviness, etc. on the window and has a good finish and is degradable in a natural environment. It was wanted.

[0006]

The present inventors have completed the present invention as a result of intensive studies to solve the above-mentioned problems. That is, the gist of the present invention consists of a polylactic acid-based polymer and has a shrinkage ratio of 0.5 to 5% at 80 ° C./10 min.
And the haze is 10% or less, and the average roughness R of the surface is
It is composed of a laminate of stretched film (A) and paper (B) in which a is more than 0.01 and 0.08 or less, and a window through which the inside of the box can be seen has two, three or four sides adjacent to each other. The stretched film (A) is provided in a window-attached box with the window stretched over the two sides of the box. As a preferred embodiment of the present invention, the window sticking box in which at least one surface of the stretched film (A) is corona treated, and the window in which both surfaces of the stretched film (A) are corona treated. Sticking box, the above window sticking box in which the surface wetting index of the stretched film (A) is 40 to 55 dyn / cm, and the above window sticking in which the stretched film (A) and the paper (B) are laminated at 60 to 80 ° C. There is a box.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

The window-attached box in the present invention refers to FIGS.
And as in the example shown in FIG. 3, in a paper packaging box for products or the like, a window is opened so that the contents can be seen through,
The film is laminated on top of 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 adjacent surfaces, three surfaces or four 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 a small amount of other hydroxycarboxylic acid unit as a copolymerization component. It may also contain a small amount of chain extender residues.

As the polymerization method, known methods such as a condensation polymerization method and a ring-opening polymerization method can be adopted. For example, in the polycondensation method, L-lactic acid, D-lactic acid, or a mixture thereof can be directly dehydrated and polycondensed to obtain polylactic acid having an arbitrary composition.

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

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

Monomers copolymerized with polylactic acid include optical isomers of lactic acid (D-lactic acid for L-lactic acid, 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, etc. Examples thereof include bifunctional aliphatic hydroxycarboxylic acids and lactones such as caprolactone, butyrolactone and valerolactone.

For the purpose of adjusting various physical properties, a heat stabilizer, a light stabilizer, a light absorber, a lubricant, a plasticizer, an inorganic filler, a coloring agent,
A pigment or the like can also be added.

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

In the production of a uniaxially stretched film, there are stretching only in the longitudinal direction by the roll method and stretching only in the transverse direction by the 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 transverse stretching is performed by a tenter method, and a simultaneous biaxial stretching method in which longitudinal and transverse stretching is simultaneously performed by a tenter are general.

The stretching conditions are 1.5 to 6 in the machine direction.
Double and laterally in the range of 1.5 to 6 times. Particularly, from the viewpoint of film strength and thickness accuracy, it is preferable that the uniaxial stretching is 3 times or more and the biaxial stretching is 2 times or more in each of the longitudinal and lateral directions. Further, the area stretching ratio obtained by multiplying the longitudinal and lateral stretching ratios is 6 or more. It is preferably set to be 5 times or more.

In the uniaxial stretching method, the stretching temperature is 70-9.
In the sequential biaxial stretching method at 0 ° C., the longitudinal stretching temperature is 70.
To 90 ° C and the transverse stretching temperature is preferably in the range of 70 to 80 ° C. In the simultaneous biaxial stretching method, the stretching temperature is in the range of 70 to 80 ° C in the sense that it is included in the sequential biaxial stretching method. Stretching is preferred. When the stretching ratio and the stretching temperature are not within the above ranges, the thickness accuracy of the obtained film is remarkably reduced, and this tendency is particularly remarkable in the film which is heat-treated after stretching. Such a thickness deviation causes a wrinkle, a wavy appearance, etc. on the product in the secondary processing such as printing a film, lamination with another film or metal thin film, paper, and bag making. It becomes such a factor.

In the present invention, it is important to control the shrinkage rate of the film. That is, the preferable shrinkage rate is 0.5 to 5% at 80 ° C./10 minutes. If the shrinkage rate is too low, it will become a window, and after lamination with paper with holes, the film will show
Looseness, waviness, wrinkles, etc. are present and it does not finish cleanly. If it is too high, the heat applied during lamination causes the film to largely shrink, causing wrinkles, and a problem that the laminated body with the paper after laminating curls. When the shrinkage ratio is in the above range, the film slightly shrinks during lamination, and the window-attached box has a good finish without sticking, waving, or wrinkling of the film attached to the window. More preferable shrinkage rate is 80 ° C./10 min
Is 1 to 3%.

In the lamination of the film and the paper, it is important to have a good slippage in consideration of the suppression of static electricity generation in the process and the finish without wrinkles. The method of applying a wax-like material to the film surface is the simplest method for improving the slippage of the film, but this is not a preferable method because it lowers the adhesive force between the film and the paper. A second method is a method of mixing inert inorganic particles in a polylactic acid-based polymer and projecting the particles onto the film surface in the stretching process to roughen the surface. As a result, the contact area between the films or paper or the like is reduced, and slippage 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 is increased, and the slipperiness is low. On the other hand, if the average roughness Ra is too large, the light scattering on the surface of the film becomes severe, and the transparency decreases. With respect to transparency, the object of the present invention is to provide a window-attached box through which the contents can be seen, and a haze of 10% or less, preferably 5% or less. For films with haze over 10%,
Although it is possible to see through the contents, it does not have the sense of cloudiness and lacks clarity.

In order to suppress the heat shrinkage of the film, it is necessary to perform heat treatment while holding the film. Usually, in the roll method, the film is stretched and then heat-treated by being brought into contact with a heating roll, and in the tenter method, the film is stretched while a film is held by a clip, so that the film is immediately heat-treated. The heat treatment temperature depends on the melting point of the polylactic acid polymer used, but the heat treatment is carried out at 110 to (melting point −10) ° C. for 3 seconds or more. When it is below this range, the heat shrinkage rate of the obtained film is high, and problems such as shrinkage of the film during processing tend to occur in the above-mentioned film laminating step.
When the heat treatment temperature is (melting point −10) ° C. or higher, the surface of the film is remarkably roughened during the heat treatment, and the film is whitened to impair transparency. Above the melting point, the film melts, causing breakage.

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. Making the corners of the box clear means, as shown in FIG. 3, when the laminate with paper is folded in the shape of a box, the film itself is cornered where the window spans two sides of the box. .
Says that the corner is neatly folded into a line. With a flexible film, corners cannot be attached, and there is slackness and waviness in this area. This concerns the self-supporting nature of the film.

The stretched film (A) used in the present invention
Should be corona treated before being combined with paper.
By performing corona treatment, the wettability of the film surface can be improved, and an adhesive agent can be applied to improve the adhesive force after bonding with paper. A film without corona treatment will peel off from the paper with a slight force. The corona treatment can be used by a known device that has been used conventionally. The surface of the film to be corona treated is the surface used for bonding with paper. However, the laminate laminated with the paper is punched into a mold as shown in the development view of FIG. An adhesive is applied to the margin as shown in the figure or drip is applied to wrap the laminated body as shown in the development view so that the inside of the paper and the margin are connected. This margin is on the opposite side of the film that is attached to the paper. Therefore, since the adhesive is applied on the film, if external force is applied even if it is pasted, for example, with the product in the box, the film and the adhesive can be easily attached by the impact of an accidental drop. Peeling may occur at the interface with. Therefore, if a stronger adhesive force 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 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, paperboard and the like.

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, hot melt lamination and the like. As described above, it is preferable to laminate at 60 to 80 ° C. from the viewpoint of enhancing the beauty of the film on the window-attached portion. If the temperature during lamination is too low, the film will not shrink, and if the temperature during lamination is too high, the shrinkage ratio will be too high.

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

The layer structure of the material for the window-attached box of the present invention has a two-layer structure of stretched film (A) / paper (B), and three layers of stretched film (A) / paper (B) / stretched film (A). The structure and the like may be mentioned, but the structure is not particularly limited.

The laminated body composed of the laminated film and paper is punched out, for example, as in the development view shown in FIG. 1, and then made into a box by an automatic box making machine or manually. When using the automatic box making machine, apply adhesive to the margin from the development view shown in FIG. 1 and bond them together, and after making a folded state as shown in FIG. 4, suck up and down as shown in FIG. To stand up and fill the contents. However, the suitability for automatic box making differs depending on the standing condition, and the angle θ shown in FIG.
If it is close to °, it will be in a preferable state. As a measure of the suitability for automatic box making, it is 20 ° or less, preferably 10 ° or less.

[0031]

EXAMPLES Examples will be shown below, but the present invention is not limited thereto. The measurements and evaluations shown in the examples were carried out under the following conditions.

Evaluation method (1) Melting point Using DSC-7 manufactured by Perkin Elmer, JIS-K71
The melting point was measured based on 21. That is, after 10 mg of the test piece from the film was conditioned in a standard state, the endothermic peak was obtained from the DSC curve drawn during heating up 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 into 140 mm (width 10 mm) in the longitudinal direction (MD) and the orthogonal direction (TD), and a front line of 100 mm was inserted between them and placed in a hot water bath at 80 ° C. After soaking for 5 minutes, the dimension between the evaluation lines was measured, and the heat shrinkage rate was calculated according to the following formula.

[0034]

[Equation 1]

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

(4) The surface roughness was measured according to the method described in JIS B0601. Surface roughness measuring instrument (S
E-3F) was used to determine the center line average roughness Ra and the ten-point average roughness (Rz). The radius of the stylus tip 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 The measurement was performed according to JIS K 6788.

(6) Lamination Suitability An adhesive was evenly applied to A3 size cardboard with a small window formed at a predetermined position, and the film cut into A3 was then pressure-bonded with a manual roller. The adhesive used was Takelac A-991 / Takenate A-19 (mixed at a ratio of 15/1) (manufactured by Takeda Pharmaceutical Co., Ltd.). Immediately, this laminate was kept in an oven at 60 ° C. for 1 minute to be dried. Then, the appearance of this film and the adhesive force between the paper and the film were observed. Those having wrinkles due to shrinkage, those having a curled laminate and those easily peeled off were marked with "X", and those not so were marked with "O".

(7) After the finish (6) of the window-attached portion was evaluated, the window-attached portion was observed, and the
Waveforms and wrinkles were marked with an X, and those without a wrinkle were marked with a ○.

(8) A laminate produced by the automatic box-making suitability (6) and aged at 38 ° C. for 48 hours or more is punched out as shown in the development view of FIG. I stuck them together and folded them in half. 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 (a), it is raised and lowered by hand to stand on it, and further, as shown in FIG. 6 (b), it is crushed up to 45 ° by applying a load in reverse, over a square. After that, the standing condition of the box when the load is not applied is as shown in Fig. 6 (c).
Was measured and evaluated. When this numerical value was 20 ° or less, it was described as ◯ in a good state, and when not, it was described as x.

(9) Drop test A log of 150 g was placed in the box prepared in (8) and sealed. This was dropped onto a concrete floor surface from a height of 1 m. The box was deformed due to the impact after it was dropped, and in particular, the bonded portion was observed. The case where complete peeling is observed in the margin portion is indicated as ×, the case where the joint is slightly stopped is indicated as Δ, and the case where there is almost no abnormality is indicated as ○.

Example 1 Polylactic acid having a ratio of L-lactic acid component and D-lactic acid component of 95: 5 and a molecular weight of about 200,000, and granular dioxide manufactured by Fuji Silysia Chemical Ltd. having an average particle diameter of about 2.5 μm. Silicon (silica)
(Brand name: Sylysia 430) After drying 1 part by weight of each to sufficiently remove water, the mixture is put into a Φ40 mm same-direction twin-screw extruder, melt-mixed at about 200 ° C., and extruded into a strand. , While cooling, cut into pellets. These pellets are used as a masterbatch, dried again, mixed with the same dried polylactic acid as 10%, and Φ
Put into a 40mm same-direction twin-screw extruder and set temperature 210 ℃
Then, it was extruded into a sheet and rapidly cooled and solidified by a rotating cooling drum to obtain a substantially amorphous sheet. 2. The obtained sheet is heated in combination with an infrared heater while being in contact with a hot water circulation type roll, and 75 ° C in the longitudinal direction between the peripheral speed difference rolls.
0 times, then guide this longitudinally stretched sheet to a tenter while gripping with a clip, and in the vertical direction of the film flow at 75 ° C.
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 surface treatment in air by a corona treatment machine so that the wettability index shown in Table 1 was obtained, if necessary. As shown in Table 1, the corona treatment on the surface is performed on both sides or only on one side.

Example 2, Comparative Examples 2-5 The films 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.).
Manufactured, trade name: Sylysia 770) was used.

Example 3 Polylactic acid having a ratio of L-lactic acid component to D-lactic acid component of 98: 2 and a molecular weight of about 220,000, and granular dioxide manufactured by Fuji Silysia Chemical Ltd. having an average particle size of about 2.5 μm. Silicon (silica)
(Brand name: Sylysia 430) After drying 1 part by weight of each to sufficiently remove water, the mixture is put into a Φ40 mm same-direction twin-screw extruder, melt-mixed at about 200 ° C., and extruded into a strand. , While cooling, cut into pellets. These pellets are used as a masterbatch, dried again, mixed with the same dried polylactic acid as 10%, and Φ
Put into a 40mm same-direction twin-screw extruder and set temperature 210 ℃
Then, it was extruded into a sheet and rapidly cooled and solidified by a rotating cooling drum to obtain a substantially amorphous sheet. The obtained sheet is used in combination with an infrared heater while being brought into contact with a hot water circulation type roll, and is heated at 77 ° C. in the longitudinal direction between the peripheral speed difference rolls.
6 times, then guide this longitudinally stretched sheet to a tenter while gripping with a clip, and 72 ° C in the vertical direction of the film flow.
After stretching 2.8 times, it was heat-treated at 135 ° C. for about 15 seconds to produce a film having a thickness of 15 μm.

Comparative Example 1 The films in Table 1 were produced in the same manner as in Example 3.

[0048]

[Table 1]

[0049]

According to the present invention, the suitability for an automatic box making machine is good,
It is possible to provide a window-pasted box which is free from looseness, wrinkles, waviness, and the like on the window and has a good finish and is degradable in a natural environment.

[Brief description of drawings]

[Figure 1] Development view of a box with a window

FIG. 2 is a diagram of a window-attached box in which the development view of FIG. 1 is assembled.

[Fig. 3] A diagram of a window-attached box with windows extending over two sides of the box

FIG. 4 is a diagram in which the development view of FIG. 1 is punched out, adhesive is applied to the margin, and the sheets are stuck together and folded in two.

FIG. 5 is a diagram in which the upper and lower parts of the folded state of FIG.

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

[Explanation of symbols]

1 seaweed 2 Whole surface laminating (film pasting) 3 windows (paste film) 4 suction direction 5 Cause direction 6 load direction

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3E060 AA03 AB03 BA02 BC04 CB07                       CB16 DA22 DA25 DA30                 3E086 AA12 AB01 AC25 AD02 BA04                       BA14 BA15 BB90 DA01

Claims (5)

[Claims] 1. A polylactic acid-based polymer, 80 ° C./1
The stretched film (A) and paper (B) having a shrinkage ratio of 0 to 5% at 0 min, a haze of 10% or less, and an average surface roughness Ra of more than 0.01 and 0.08 or less. ), A window through which the inside of the box can be seen is provided across two, three or four sides of the box,
A window-attached box in which the stretched film (A) is cornered where the window extends over two sides of the box. 2. The window-attached box according to claim 1, wherein at least one surface of the stretched film (A) is corona-treated. 3. The window sticking box according to claim 1, wherein both surfaces of the stretched film (A) are corona treated. 4. The stretched film (A) has a surface wetting index of 4
It is 0-55 dyn / cm, It is characterized by the above-mentioned.
The window-attached box according to any one of 1 to 3. 5. The stretched film (A) and the paper (B) 60
Laminated at ~ 80 ° C.
The box with a window according to any one of 1 to 4.