JP2003073977A - Cellulosic fiber structure, laminate, composite container and method for producing the same composite container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite container which is excellent in readily disposable property, water resistance, heat resistance and hot water resistance and is readily produceable. SOLUTION: The composite container is produced by using a cellulosic fiber structure having a container shape in which whole of a fiber layer is impregnated with an isocyanate-based resin and which has one or more notches on one side and a plastic film having an adhesive resin layer on one side and turning the side having the adhesive resin layer of the plastic film on the side having notches of the cellulosic fiber structure and bonding the cellulosic fiber structure through the adhesive resin layer to the plastic film by vacuum forming.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a cellulose fiber structure, a laminate, a composite container, and a method for producing a composite container.

[0002]

2. Description of the Related Art In recent years, the seriousness of environmental problems due to an increase in waste has become a major social problem, and in order to solve this problem, containers and packaging materials need to be easily disposed of, and easily incinerated. The demand for containers and packaging materials that use recyclability or recycled materials is increasing.

There are great social demands for reducing the volume and recycling of garbage, and even in the packaging container market, it is possible to lightly incinerate instead of metal tubes, glass tubes, plastic bottles, wooden boxes, etc. and recycle them into recycled paper. In many cases, a container whose main material is a cellulosic fiber structure that can be used is used.

Pulp, which is the main raw material of the cellulose fiber structure, is a recyclable resource, and since the circulation period is significantly shorter than that of petroleum, a container using the cellulose fiber structure is desired in the market.

Here, the cellulosic fiber structure means a structure mainly composed of fibers containing cellulose as a main component. For example, paper is a cellulose fiber structure that is sheet-like in shape. Further, for example, a pulp mode formed into a three-dimensional shape is also a cellulose fiber structure.

By the way, when a cellulose fiber structure is used as a container for filling a liquid or the like, at least one plastic film is provided as an inner layer to form a composite container.

As one of the manufacturing methods for this composite container,
Some use vacuum molding to bond a cellulose fiber structure having excellent hot water resistance and a plastic film. As shown in FIG. 1, a container-shaped cellulose fiber structure is placed in a mold, a plastic film is heated by a heater to be softened, the adhesive resin provided on the plastic film is melted, and It is a manufacturing method in which a plastic film and a cellulose fiber structure are physically and chemically adhered to each other to be a composite container by drawing a negative pressure from a vacuum hole provided and transferring the cellulose fiber structure to a cellulose fiber structure.

[0008]

However, there is a problem that the adhesive strength is remarkably reduced due to a decrease in the amount of heat held by the plastic film during the time from the softening to the transfer to the cellulose fiber structure. .

When the thickness of the plastic film is reduced in order to reduce the amount of plastic used, the maximum amount of heat that the plastic film can hold decreases.

In vacuum forming, when the initial maximum amount of heat given to the plastic film is lowered because heat is radiated in the time after the plastic film is heated and before it is transferred to the cellulose fiber structure, the cellulose fiber structure and the plastic film are reduced. In some cases, the amount of heat required for bonding with the film cannot be maintained in the plastic film.

Generally, the larger the draw ratio obtained from the ratio of the inner surface area of the container to the upper opening area of the container, the longer the time required for transfer. In the case of comparing two types of a container having a constant opening area and having a shallow depth and a deep depth, it takes longer time to transfer the deeper one.

If the amount of heat given to the plastic film is made excessive in order to improve this, a part where the heat distribution is not stable and it becomes extremely thin when it is transferred to a container-shaped cellulose fiber structure, A defect called a pinhole occurs.

Further, in the case of a cellulose fiber structure impregnated with an isocyanate resin to impart water resistance, heat resistance and hot water resistance, it becomes more difficult to adhere a plastic film by vacuum forming. this is,
The reason is as follows.

Generally, a cellulose fiber structure has unevenness in surface condition and is inferior in water repellency as compared with a plastic film.

However, since the cellulose fiber structure impregnated with the isocyanate resin has water resistance and hot water resistance, the wettability thereof is close to that of plastic.

Further, since the paper grain is also filled by the impregnation, the anchoring effect cannot be expected for adhesion.

Although the isocyanate resin is on the surface of the cellulose fiber structure, the functional group reacts with moisture in the air and moisture in the cellulose fiber structure to form a urethane bond. It is difficult to use and bond with an adhesive.

In the hot water treatment, when the adhesive force of the adhesive resin for adhering the cellulose fiber structure and the plastic film is insufficient, the plastic film causes delamination (peeling) from the cellulose fiber structure due to air expansion.

The present invention has been made in view of the drawbacks of the prior art, and it is an object of the present invention to provide a composite container which is excellent in easy disposal, water resistance, heat resistance and hot water resistance and is easy to manufacture.

[0020]

In order to achieve the above-mentioned object in the present invention, first, in the invention of claim 1, all the fiber layers of the cellulose fiber structure are impregnated with an isocyanate resin, and one side is A cellulose fiber structure having one or more notches.

The invention of claim 2 provides the cellulose fiber structure according to claim 1, wherein the basis weight before impregnated with the isocyanate resin is in the range of 500 g / m ² or less. is there.

Further, in the invention of claim 3, the shape of the notch is a hole having a diameter of 0.1 mm or more, or a linear shape having a width of 0.1 mm or more, the cellulose fiber structure according to claim 1 or 2. It is a thing.

The invention according to claim 4 is characterized in that the depth of the cut is 0.05 mm or more.
The cellulose structure according to any one of 3 above.

Further, in the invention of claim 5, a plastic film is adhered to the side having the cut of the cellulose fiber structure according to any one of claims 1 to 4 through an adhesive resin layer. Is a laminated body.

According to a sixth aspect of the present invention, the weight of the cellulose fiber structure is greater than 50% of the total weight ratio, and the laminated body according to the fifth aspect is provided.

Further, in the invention of claim 7, the melting point of the adhesive resin is 90 ° C. or higher and 145 ° C. or lower, and the laminated body according to claim 5 or 6 is provided.

[0027] According to the invention of claim 8, there is provided a container using the cellulose fiber structure according to any one of claims 1 to 4, wherein a side having a cut of the cellulose structure is
A composite container is characterized in that a plastic film is adhered via an adhesive resin layer.

The invention of claim 9 provides the composite container according to claim 8, characterized in that the weight of the cellulose fiber structure is more than 50% with respect to the total weight ratio.

The invention of claim 10 provides the composite container according to claim 8 or 9, characterized in that the melting point of the adhesive resin is 90 ° C or higher and 145 ° C or lower.

According to the invention of claim 11, claims 1 to 4 are provided.
When the cellulose fiber structure according to any one of claims 1 to 4 is molded into a container shape, or when the cellulose fiber structure according to any one of claims 1 to 4 has a container shape,
This container-shaped cellulose fiber structure is a method for producing a composite container by adhering a plastic film having an adhesive resin layer on one side, by vacuum molding, on the side having a cut of the cellulose fiber structure, A method for producing a composite container is characterized in that a plastic film is adhered via a resin layer.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on an embodiment.

(Cellulose Fiber Structure) A cellulosic fiber structure such as general plain paper, corrugated paper, coated cardboard, cup base paper, or pulp molded body made from slurry pulp is the main material of the container. It can be preferably used.

For example, when making a container for food, a cup base paper of 100% virgin pulp and a paper thickness of 300 is used.
Those having a size of about μm are preferably used.

The basis weight of the cellulose fiber structure before being impregnated with the isocyanate resin also depends on the impregnation amount, and is 500 in view of processability, cost, rigidity performance and the like.
It is preferably g / m ² or less. Of course, the basis weight of the cellulose fiber structure before being impregnated with the isocyanate resin is larger than 0 g / m ² .

However, since it may be used for applications other than food applications, it is possible to use paper made from 100% virgin pulp, recycled paper made from recycled waste paper, or paper made in the papermaking process. It is also possible to use any of the base papers made by stacking the above papers as the main material of the container.

The cellulosic fiber structure as the main material of the container is not limited in material and constitution.

(Impregnation of isocyanate resin)
The isocyanate resin used as the impregnating agent acts by adhering to the joints between the fibers of the cellulose fiber structure which is the material to be impregnated, strengthens the joints, and external stress acts on the fiber structure. The effect of preventing fiber misalignment is extremely large. After that, in order to simplify the explanation,
The cellulose fiber structure impregnated with the isocyanate resin is also simply referred to as an impregnated product.

The isocyanate resin can be spread in the fiber layer to a certain depth and in the entire layer to change the concentration distribution of the isocyanate resin to be propagated in the fiber structure.

The type and amount of the isocyanate resin may be appropriately determined according to the purpose and level of use, and the amount of addition should be 10% or less of the absolute dry weight of the impregnated product and distributed in all layers of the fiber structure. The effect can be expressed.

By impregnating the isocyanate resin, the cellulose fiber structure is efficiently and heat-resistant,
Functions such as water resistance and hot water resistance can be imparted.

After use, it may be incinerated as paper, and when it is recycled, it can be separated by defibration with an alkali used in a normal paper recycling line.

(Form of Notch) As shown in FIG. 2, the notch formed on one side of the impregnated material may be a hole, a line (slit), or a lattice. good. Here, the one side is the side to which the plastic film is adhered.

In the case of a hole, it is desirable to make a few to several tens of cuts having a diameter of 0.1 mm or more and having a depth of 10 μm or more at locations where adhesion failure is likely to occur in vacuum forming. The upper limits of diameter and depth are undetermined and are not set in particular.

In the case of a linear (slit-shaped) cut, a cut having a width of 0.1 mm or more and a length of several mm and a depth of 10 μm or more may be made at a place where adhesion failure is likely to occur. The upper limits of width and depth are undetermined and are not set in particular.

There are no restrictions on the method of making the notches, the location, the number of notches, and the like.

Basically, in the step of forming into the shape of the container, the cutting edge may be provided with a notch with a needle or the like.

(Plastic Film) The plastic film is preferably a single-layer plastic film or a laminated plastic film having at least one adhesive resin layer on one side.

Basically, it is preferable to use a polyolefin resin having a good vacuum forming property.

It is necessary to provide at least one layer of adhesive resin on one side of the plastic film in order to provide adhesiveness to the cellulose fiber structure impregnated with the isocyanate resin.

In view of the required oxygen barrier property and the like, the layer structure of the plastic film is EV if the barrier property is required.
The configuration may be such that the OH layer is provided, or if the barrier property is not required, the configuration without the barrier layer may be employed.

However, the method and material used for imparting the barrier property are not limited to EVOH and the like. For example, it is also possible to deposit a barrier material on a container or to deposit a barrier material on paper to have it. The method and material are not limited. Further, the thickness and layer structure of the plastic film are not limited.

(Adhesion in Vacuum Forming) When a plastic film and an impregnated product are adhered by vacuum forming, which is one of the forming methods, as shown in FIG. 2, first, the impregnation is temporarily formed into a container shape. An object is placed in a mold, the plastic film is heated, and then a negative pressure is drawn from a vacuum hole provided in the mold to transfer the plastic film to the impregnated product side to form a composite container.

As described above, for adhesion, the plastic film must hold the amount of heat required for adhesion at the moment of transfer in order to melt the adhesive resin and adhere it to the cellulose fiber structure.

A cross-sectional view of the composite container is shown in FIG. The physical anchoring effect of the cuts made in the impregnant improves the bond strength between the plastic film and the impregnant.

As can be understood from the sectional view of FIG. 3, the composite container has the following layer structure. (Outside) Impregnated material / Adhesive resin / Plastic film (Inside)

When the composite container is used as a food container,
The part that comes into direct contact with food is the plastic film in the inner bag.

(Regarding Adhesive Resin) The melting point of the adhesive resin is required to be higher than the temperature for treating the composite container.
Because, if the melting point of the adhesive resin is lower than the processing temperature of the composite container, the adhesive resin lacks the adhesive force due to the treatment, and the plastic film causes delamination (peeling) from the impregnated material due to air expansion. Because.
Therefore, for composite containers, boil treatment at 100 ° C, 1
When performing retort treatment at 10, 125, 135 ° C,
In order to prevent delamination at each temperature, it is necessary for the adhesive resin to have a melting point above each temperature.

Although a general adhesive resin can be used, a modified polyolefin resin is preferably used.

By using an adhesive resin having a melting point of 135 ° C. or higher, the composite container has excellent water resistance and heat resistance and can withstand hot water treatment at 135 ° C.

[0060]

EXAMPLES First, items common to each example and each comparative example will be described.

(Regarding Paper) In Examples 1 to 3, the base paper used was a cup base paper having a basis weight of 300 g / m ² and an isocyanate resin of 10 g / m 2.
All layers were impregnated with a coating amount of ² . The thickness is about 300 μm. Hereinafter, for simplification of description, the cup base paper impregnated with the isocyanate resin is simply referred to as impregnated paper.

(About the vacuum forming machine) The vacuum forming machine is PL
An AVAC vacuum forming machine was used. The film heating portion heater output is 100% of 1400 W for molding, and the amount of heat applied to the film is adjusted by setting the heating time. During the evacuation time, the strength of the vacuum was constant and molding was performed.

(About the film) The film is Aroma TC160 160 μm (Showa Denko), layer structure
PP 130 μm / adhesive resin 30 μm, adhesive resin grade Adtex ER333F2 (Japan Polyolefin) Pace PP system, Tm 134 ° C. were used.

Each embodiment will be described below.

Example 1 The impregnated paper was processed into a paper container having the following dimensions, and a vacuum forming test was conducted. Frontage short side 50mm Frontage long side 60mm Bottom short side 40mm Bottom long side 50mm Depth 40mm

(Cuts) Shape Hole size Diameter 0.5 mm Depth 100 μm Arrangement Number arranged on one entire surface of impregnated paper Number (density) 9 pieces / cm ²

(Vacuum forming) Heating condition 7sec

(Evaluation results) The moldability was satisfactory for both pinholes and adhesion.

When the composite container prepared above was subjected to retort treatment at 125 ° C., the shape was maintained, there was no delamination (peeling) between the film and the impregnated paper, and no liquid leakage occurred.

Here, it was possible to perform tray molding having excellent hot water resistance in the above dimensions.

Example 2 The impregnated paper was processed into a paper container having the same dimensions as in Example 1 and subjected to a vacuum forming test.

(Notch) Shape Slit (Linear) Width 0.5 mm Depth 100 μm Arrangement Arranged on one side of the impregnated paper Number (density) 3 / cm ²

(Vacuum forming) Heating condition 7sec

(Evaluation results) The moldability was satisfactory for both pinholes and adhesion.

When the composite container prepared above was subjected to retort treatment at 125 ° C., its shape was maintained, neither delamination (peeling) between the film and the impregnated paper nor liquid leakage occurred.

Here, it was possible to carry out tray molding having excellent hot water resistance in the above-mentioned dimensions.

Example 3 The impregnated paper was processed into a paper container having the same dimensions as in Example 1 and a vacuum forming test was conducted.

(Cut) Shape Slit (Linear) Width 0.5 mm Depth 100 μm Arrangement Partially arranged on one side of the impregnated paper (arranged on the bottom of the container) Number (density) 3 pieces / cm ²

(Vacuum forming) Heating condition 7sec

(Evaluation Results) The moldability was satisfactory for both pinholes and adhesion.

When the above-prepared composite container was subjected to retort treatment at 125 ° C., the shape was maintained, there was no delamination (peeling) between the film and the paper, and no liquid leakage occurred.

Here, it was possible to perform tray molding having excellent hot water resistance in the above dimensions.

Each comparative example will be described below.

<Comparative Example 1> The impregnated paper was processed into a paper container having the same dimensions as in Example 1 and subjected to a vacuum forming test.

(Notch) None

(Vacuum forming) Heating condition 7sec

(Evaluation result) Formability has a problem in adhesion,
The side surface of the container had sufficient strength, but the bottom surface had insufficient adhesive strength. for that reason,
At the bottom of the retort treatment, peeling occurred at the interface between the film and the impregnated paper.

<Comparative Example 2> The impregnated paper was processed into a paper container having the same dimensions as in Example 1 and subjected to a vacuum forming test.

(Notch) None

(Vacuum forming) Heating condition 8sec

(Evaluation result) Although the adhesive strength was sufficient,
As for moldability, a pinhole was generated at the thinnest part of the film. Therefore, liquid leakage occurred when the liquid was filled.

Comparative Example 3 The impregnated paper was processed into a paper container having the following dimensions, and a vacuum forming test was conducted. Frontage short side 50mm Frontage long side 60mm Bottom short side 40mm Bottom long side 50mm Depth 20mm

(Notch) None

(Vacuum forming) Heating condition 7sec

(Evaluation results) The moldability was satisfactory for both pinholes and adhesion.

When the composite container prepared above was subjected to retort treatment at 125 ° C., the shape was maintained, there was no delamination (peeling) between the film and the impregnated paper, and no liquid leakage occurred.

With a bottom depth of 20 mm, it was possible to perform tray molding having excellent hot water resistance in the above dimensions. However, since the shape of the container is limited, the shape and size of the food material are also limited.

A list of the above examples and comparative examples
As shown in FIG.

[0099]

The invention described in each claim has the following effects.

Since the cellulose fiber structure according to the invention of claim 1 has a notch on one side, a composite container excellent in easy disposal, water resistance, heat resistance and hot water resistance can be easily formed by vacuum forming. It has the effect of being able to make it.

The cellulose fiber structure according to the second aspect of the present invention has a basis weight of 500 g / m ² before being impregnated with the isocyanate resin, and therefore, in view of processability, cost, rigidity performance and the like. It has the effect of being excellent.

In the cellulose fiber structure according to the invention as defined in claim 3, the shape of the notch is a hole having a diameter of 0.1 mm or more, or a linear shape having a width of 0.1 mm or more. When a plastic film is adhered via a resin, it has an effect of exerting an excellent anchoring effect.

In the cellulose fiber structure of the present invention as defined in claim 4, since the depth of cut is 0.5 mm or more,
When a plastic film is adhered to the cut side through an adhesive resin, it has an effect of exhibiting an excellent anchoring effect.

The laminate according to the invention of claim 5 is excellent in easy disposal, water resistance, heat resistance and hot water resistance, and has an effect that it can be easily manufactured by vacuum forming.

In the laminate according to the invention of claim 6, the weight of the cellulose fiber structure which can be discarded as paper is 50%.
Since it is larger than the above, there is an effect that the easy disposal property becomes particularly excellent.

Since the melting point of the adhesive resin is 90 ° C. or higher and 145 ° C. or lower in the laminate according to the invention of claim 7,
Since the plastic film can be easily peeled off from the cellulose fiber structure by sufficiently withstanding the hot water treatment and melting the adhesive resin at a temperature higher than the melting point, the effect that the easy disposability becomes particularly excellent is obtained. is there.

The composite container according to the invention of claim 8 is
It has excellent effects of easy disposal, water resistance, heat resistance, and hot water resistance, and can be easily manufactured by vacuum forming.

The composite container according to the invention of claim 9 is
Cellulose fiber structure that can be discarded as paper weighs 50
Since it is larger than%, there is an effect that the easy disposal property becomes particularly excellent.

Since the melting point of the adhesive resin is 90 ° C. or higher and 145 ° C. or lower, the composite container according to the invention of claim 10 is sufficiently resistant to hot water treatment, and the temperature is not lower than the melting point. By melting the, the plastic film can be easily peeled off from the cellulose fiber structure, so that there is an effect that the easy disposability becomes particularly excellent.

The method for producing a composite container according to the invention of claim 11 has an effect that a composite container excellent in easy disposal, water resistance, heat resistance and hot water resistance can be easily produced.

As described above, the present invention has the effect of providing a composite container which is excellent in easy disposal, water resistance, heat resistance and hot water resistance and which can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a diagram illustrating vacuum forming.

FIG. 2 is a diagram illustrating a shape of a cut provided in an impregnated material.

FIG. 3 is a sectional view of a composite container according to the present invention.

FIG. 4 is a diagram showing a list of examples and comparative examples.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // D06M 101: 06 D06M 101: 06 (72) Inventor Masao Nakajima 1-5-1 Taito, Taito-ku, Tokyo No. Topographic Printing Company F Term (Reference) 3E060 BC04 BC08 DA25 DA30 3E075 AA28 BA30 BB02 CA01 DC37 GA03 4F100 AJ04A AK01B AK01C AK07 AK51A BA03 BA07 BA10A BA10B DC13A DC15A DC16A EJ821 GB16 JA11C00A00J03C00L02 AC11 AC15 CA50

Claims (11)

[Claims] 1. In all the fiber layers of the cellulose fiber structure,
A cellulose fiber structure which is impregnated with an isocyanate resin and has one or more notches on one side. 2. The cellulose fiber structure according to claim 1, wherein the basis weight before being impregnated with the isocyanate resin is in the range of 500 g / m ² or less. 3. The cellulose fiber structure according to claim 1, wherein the shape of the cut is a hole having a diameter of 0.1 mm or more, or a linear shape having a width of 0.1 mm or more. 4. The cellulosic structure according to any one of claims 1 to 3, wherein the notch depth is 0.05 mm or more. 5. A laminate, wherein a plastic film is adhered to the side having the cut of the cellulose fiber structure according to any one of claims 1 to 4 through an adhesive resin layer. . 6. The weight of the cellulosic fiber structure is greater than 50%, based on the total weight ratio.
The laminate described. 7. The melting point of the adhesive resin is 90 ° C. or higher and 145 ° C.
It is the following, The laminated body of Claim 5 or 6 characterized by the above-mentioned. 8. A container using the cellulose fiber structure according to any one of claims 1 to 4, wherein a plastic film is provided on the cut side of the cellulose structure via an adhesive resin layer. A composite container characterized by being adhered. 9. The weight of the cellulosic fiber structure is greater than 50%, based on the total weight ratio.
The composite container described. 10. The melting point of the adhesive resin is 90 ° C. or higher and 145.
10. The composite container according to claim 8 or 9, wherein the temperature is not higher than ° C. 11. A case where the cellulose fiber structure according to any one of claims 1 to 4 is molded into a container shape, or the cellulose fiber structure according to any one of claims 1 to 4 is a container. A method for producing a composite container by adhering this container-shaped cellulose fiber structure to a plastic film having an adhesive resin layer on one side when the container has a shape, and forming a cellulose fiber structure by vacuum forming. A method for producing a composite container, comprising: adhering a plastic film to a side having a notch through an adhesive resin layer.