JP6093653B2 - Cellulose-containing container - Google Patents

Description

 The present invention relates to a cellulose-containing container.

In recent years, in the field of synthetic resin molded products, as one of environmental measures, composite materials containing cellulose and synthetic resin contained in biomass (wood flour, bamboo flour, rice flour, etc.) have been used.
Among these composite materials, materials having a cellulose content of 50% by mass or more are commercialized as building materials such as wood decks and furniture, and materials having a cellulose content of less than 50% by mass are chopsticks, plates, and toys. It has been commercialized as daily necessities. These molded articles are molded by extrusion molding or injection molding.

 Conventionally, a container formed by press-molding a paper sheet obtained by using pulp or other natural or regenerated fibers as cellulose and processing the material containing 5 to 20% by mass of an olefin resin into a sheet has been disclosed. (For example, refer to Patent Document 1).

JP-A-6-239334

 However, it is difficult to use a composite material having a cellulose content of 50% by mass or more for blow molding, and it is difficult to form a bottle-shaped molded product by blow molding. The reason for this is that when a composite material having a high cellulose content is used, the cellulose is burnt by heat during molding, resulting in poor appearance and bad odor. In addition, when a composite material having a high cellulose content is used, there is a problem in that the adhesiveness between cellulose and the synthetic resin is poor, the composite material cannot withstand stretching during blow molding, and blow molding cannot be performed.

 The present invention has been made in view of the above circumstances, and prevents the occurrence of poor appearance and bad odor due to heat during molding of a composite material containing cellulose, and enables the molding by blow molding The purpose is to provide a container.

The cellulose-containing container of the present invention includes a container main body formed by melt-molding a composite material containing cellulose and polypropylene, and the container main body has a three-layer configuration of an inner layer / intermediate layer / outer layer, the inner layer and the The outer layer is composed of the polypropylene, the intermediate layer is composed of the composite material, and the polypropylene has a melting start temperature of 90 ° C. or less and a melting peak temperature of 140 ° C. or less, as measured by a differential scanning calorimeter (DSC), The melting enthalpy is 80 mJ / mg or less, and the cellulose content is 50 mass% or more.

 According to the present invention, it is possible to provide a cellulose-containing container that can prevent a poor appearance and bad odor from being generated by heat during molding of a composite material containing cellulose and can be molded by blow molding.

It is a schematic side view of the cellulose containing container shown as 1st embodiment of this invention. It is a schematic sectional drawing of the cellulose containing container shown as 2nd embodiment of this invention. It is a graph which shows the result of the differential scanning calorimetry of Experimental example 1, 4 and 5. It is a graph which shows the result of the differential scanning calorimetry of Experimental example 2 and 3.

An embodiment of the cellulose-containing container of the present invention will be described.
Note that this embodiment is specifically described in order to better understand the gist of the invention, and does not limit the present invention unless otherwise specified.

(1) First Embodiment FIG. 1 is a schematic side view of a cellulose-containing container shown as a first embodiment of the present invention.
The cellulose-containing container 1 according to the present embodiment is, for example, a container filled with a food such as a beverage or a seasoning, or a drug such as a detergent or a medicine, and formed in a bottomed cylindrical shape. The main body 2 is generally configured.

 The container body 2 is a molded product obtained by molding a composite material containing cellulose and polypropylene (hereinafter sometimes abbreviated as “PP”) by blow molding such as extrusion blow molding or injection stretch blow molding.

As the cellulose, those contained in biomass (wood flour, bamboo flour, rice flour, etc.) are used.
Moreover, as cellulose, in order to avoid scorching due to heat at the time of melt molding, it is preferable to remove lignin that causes scorching.
Moreover, in order to improve the dispersibility with respect to PP, it is preferable that the fiber length of a cellulose is 1-10 micrometers, and it is preferable that a fiber diameter is 2.5-5 micrometers.

 As the PP, based on Japanese Industrial Standard: JIS-K-7121 “Method for Measuring Transition Temperature of Plastic” and Japanese Industrial Standard: JIS-K-7122, “Method for Measuring Transition Temperature of Plastic”, a differential scanning calorimeter (DSC: As a measurement condition, measurement was performed at a temperature increase rate of 10 ° C./min in a measurement temperature range of 30 ° C. to 210 ° C., and the melting start temperature at that time was 90 ° C. or less and the melting peak temperature was 140 ° C. Those having a melting enthalpy of 80 mJ / mg or less, a melting start temperature of 75 to 90 ° C., a melting peak temperature of 120 to 140 ° C., and a melting enthalpy of 60 to 80 mJ / mg or less are preferred.

 Using PP with melting start temperature, melting peak temperature, and melting enthalpy within the above ranges can prevent the appearance of bad appearance and bad odor of cellulose-containing containers due to heat during melt molding, and molding by blow molding is possible. It becomes. In other words, by using PP having a melting start temperature of 90 ° C. or less and a melting peak temperature of 140 ° C. or less, the molding temperature at the time of melt molding of the composite material (temperature at which PP is melted) is difficult to burn the cellulose. Since it can be 160 degrees C or less, it can prevent that a cellulose burns with the heat | fever at the time of melt molding, and that the external appearance defect and malodor of a cellulose containing container generate | occur | produce. In addition, by using PP having a melting enthalpy of 80 mJ / mg or less, PP molecules are easily dispersed in the gaps between the cellulose fibers, so that the moldability is improved by finely dispersing cellulose, and the inclusion of cellulose in the composite material Even if the rate is increased, blow molding is possible.

 On the other hand, if any one of PP melting start temperature, melting peak temperature and melting enthalpy is not within the above range, the appearance and bad odor of the cellulose-containing container 1 may occur due to heat during melt molding. Cannot be prevented, and molding by blow molding is also impossible.

Examples of such PP include those having a low molecular weight, a narrow molecular weight distribution, a low melting point, and low crystallinity. Specifically, metallocene polypropylene (trade names: WINTEC WMX03, WSX02, WFX4 manufactured by Nippon Polypro Co., Ltd.). , WFX4T).
In the present specification, the above PP may be referred to as a low melting point PP.

The cellulose content in the cellulose-containing container 1 (here, the container body 2) is 50% by mass or more, and more preferably 51 to 70% by mass.
If the content rate of the cellulose in the cellulose containing container 1 is 50 mass% or more, the content rate of a cellulose will become high compared with PP, and the addition to an environment can be reduced.
Moreover, when the cellulose containing container 1 consists only of the container main body 2, since the content rate of the cellulose in the cellulose containing container 1 can be 70 mass%, the addition to an environment can be reduced more.

Next, an example of the manufacturing method in the extrusion blow molding of the cellulose containing container 1 comprised as mentioned above is demonstrated.
In the following description, a straight line passing through the center of the cross section of the cellulose-containing container 1 is referred to as a container axis O, and a direction orthogonal to the container axis O is referred to as a radial direction.
First, the composite material is heated and melted at 160 to 180 ° C. to extrude a tube-like so-called parison, and the tube-like parison is sandwiched between blow molding dies.
Subsequently, the cellulose-containing container 1 is shape | molded by blowing air in the inside in the state which heated said parison, and blow-molding.

The lateral magnification (blow magnification in the radial direction) in the extrusion blow molding is preferably 1.1 to 1.9 times.
At this time, if the lateral magnification exceeds 1.9 times, a hole may be formed in the container body 2 or a tear may occur, which is not preferable.

 According to the cellulose-containing container 1 of the present embodiment, it is provided with a container body 2 formed by melt-molding a composite material containing cellulose and PP, and PP is Japanese Industrial Standard: JIS-K-7121 “Plastic transition temperature. Measured by a differential scanning calorimeter (DSC) based on “Measuring method” and Japanese Industrial Standards: JIS-K-7122 “Measurement method of plastic transition temperature”. As a measurement condition, the heating rate is 10 ° C./min. Measured in the range of 30 ° C. to 210 ° C., the melting start temperature at that time is 90 ° C. or lower, the melting peak temperature is 140 ° C. or lower, the melting enthalpy is 80 mJ / mg or lower, and the cellulose content is 50% by mass or higher. Therefore, it is possible to prevent poor appearance and bad odor from being generated by heat during melt molding such as blow molding, and molding by blow molding is possible. That.

(2) Second Embodiment FIG. 2 is a schematic cross-sectional view of a cellulose-containing container shown as the second embodiment of the present invention.
The cellulose-containing container 10 according to the present embodiment is generally configured from a container body 14 having a three-layer configuration of an inner layer 11 / an intermediate layer 12 / an outer layer 13, the inner layer 11 and the outer layer 13 are configured from PP, and the intermediate layer 12 is the above It is comprised from the composite material which made the content rate of the cellulose of 70 mass%.

 As PP which comprises the inner layer 11 and the outer layer 13, the thing similar to PP which comprises the intermediate | middle layer 12 is used. However, the resin used for the inner layer 11 and the outer layer 13 is not limited to the PP. In the present embodiment, the same PP as the intermediate layer 12 is used for the inner layer 11 and the outer layer 13 because the melting point is equivalent to that of the composite material forming the intermediate layer 12 and the blow moldability is improved. . Therefore, the resin constituting the inner layer 11 and the outer layer 13 is not limited to PP.

The thickness of the inner layer 11 is not particularly limited and is appropriately adjusted according to the container shape, capacity, etc., and is, for example, 100 μm to 300 μm.
The thickness of the outer layer 13 is not particularly limited, and is appropriately adjusted according to the container shape, capacity, etc., and is, for example, 100 μm to 200 μm.

 The cellulose-containing container 10 includes an inner layer 11 and an outer layer 13. Since the inner layer 11 and the outer layer 13 do not contain cellulose, the cellulose content in the cellulose-containing container 10 as a whole is 50% by mass or more, 51 More preferably, it is -70 mass%.

Next, an example of the manufacturing method in the extrusion blow molding of the cellulose containing container 10 comprised as mentioned above is demonstrated.
First, a so-called parison, which is composed of three layers, an inner layer made of PP / an intermediate layer made of composite material / an outer layer made of PP, heated and melted at 160 to 180 ° C. is extruded, and the tube-like parison is blown. Insert it with a mold.
Subsequently, the cellulose containing container 10 is shape | molded by blowing air inside the said parison in the heated state, and blow-molding.

According to the cellulose-containing container 10 of the present embodiment, it is composed of a container body 14 having a three-layer structure of inner layer 11 / intermediate layer 12 / outer layer 13, the inner layer 11 and outer layer 13 are composed of PP, and the intermediate layer 12 is cellulose. Since the content ratio of 70% by mass is composed of a composite material, the odor of cellulose contained in the composite material constituting the intermediate layer 12 is prevented from being transferred to the contents filled in the cellulose-containing container 10. it can.
Further, by using PP contained in the composite material constituting the intermediate layer 12 as a material constituting the inner layer 11 and the outer layer 13, the cellulose-containing container 10 of the present embodiment can be blow-molded and blown. It is possible to prevent appearance defects and bad odors from being generated by heat during melt molding such as molding.

 In addition, in the range which does not deviate from the meaning of this invention, it is possible to replace suitably the component in said embodiment with a well-known component, and you may combine the above-mentioned modification suitably.

 EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

[Experiment 1]
Based on Japanese Industrial Standards: JIS-K-7121 “Plastic Transition Temperature Measurement Method” and Japanese Industrial Standards: JIS-K-7122 “Plastic Transition Temperature Measurement Method” (trade name: EXSTAR, DSC6220) , Manufactured by SIINT), was subjected to differential scanning calorimetry analysis of low melting point PP (trade name: WINTEC WMX03, manufactured by Nippon Polypro). The measurement conditions were a temperature increase rate of 10 ° C./min and a measurement temperature range of 30 ° C. to 210 ° C.
The results are shown in FIG.

[Experiment 2]
In the same manner as in Experimental Example 1, differential scanning calorimetry of homo PP (trade name: J160MG, manufactured by Prime Polymer Co., Ltd.) was performed.
The results are shown in FIG.

[Experiment 3]
In the same manner as in Experimental Example 1, a differential scanning calorimetry analysis of random PP (trade name: J246M, manufactured by Prime Polymer Co., Ltd.) was performed.
The results are shown in FIG.

[Experimental Example 4]
In the same manner as in Experimental Example 1, differential scanning calorimetry of high density polyethylene (HDPE, trade name: Hizex 2100J, manufactured by Prime Polymer Co., Ltd.) was performed.
The results are shown in FIG.

[Experimental Example 5]
In the same manner as in Experimental Example 1, differential scanning calorimetry analysis of linear low density polyethylene (LLDPE, trade name: Neozex 40300J, manufactured by Prime Polymer Co., Ltd.) was performed.
The results are shown in FIG.

[Example 1]
First, low melting point PP (trade name: WINTEC WMX03, manufactured by Nippon Polypro Co., Ltd.) and cellulose (trade name: UFC-100, manufactured by Rettenmeier Co., Ltd.) in a mass ratio of 30:70 (mass%: mass%) The resulting mixture was kneaded to produce composite material pellets composed of low melting point PP and cellulose.
For the kneading of the low melting point PP and cellulose, a biaxial kneading extruder (screw diameter (D) 35.5 mm, screw length (L) 1526.5 mm, L / D = 43) rotating in the same direction is used. Was discharged at a resin temperature of 170 ° C. and the screw speed was 100 rpm.
The obtained pellet was not burnt and had a normal shape.
Using this pellet of composite material, an extrusion melting temperature was set to 165 ° C., and a cellulose-containing container composed of a container body formed into a bottomed cylinder was obtained by extrusion blow molding.
The results are shown in Table 2.

[Comparative Example 1]
Using the same twin-screw kneading extruder as in Example 1, Homo PP (trade name: J160MG, manufactured by Prime Polymer Co.) and cellulose (trade name: UFC-100, manufactured by Rettenmeier) by mass ratio It knead | mixed so that it might be set to 30:70 (mass%: mass%), and preparation of the pellet of the composite material comprised from homo PP and a cellulose was tried. The setting conditions at this time were a resin temperature of 190 ° C. and a screw rotation speed of 100 rpm when the melt-kneaded resin was discharged.
As a result, the pellets could not be produced due to the burning of the cellulose and the extrusion failure during the pellet processing.
The results are shown in Table 2.

[Comparative Example 2]
Using the same twin-screw kneading extruder as in Example 1, random PP (trade name: J246M, manufactured by Prime Polymer Co., Ltd.) and cellulose (trade name: UFC-100, manufactured by Rettenmeier) were used in a mass ratio. The mixture was kneaded so as to have a mass ratio of 30:70 (mass%: mass%) to prepare a composite material pellet composed of random PP and cellulose. The setting conditions at this time were a resin temperature of 175 ° C. and a screw rotation speed of 100 rpm when the melt-kneaded resin was discharged.
The obtained pellet was not burnt and had a normal shape.
Using this composite material pellet, the extrusion melting temperature was set to 185 ° C., and extrusion blow molding was performed. As a result, it burst at the barrel of the container and could not be molded normally.
The results are shown in Table 2.

[Comparative Example 3]
Using the same twin-screw kneading extruder as in Example 1, high-density polyethylene (HDPE, trade name: Hizex 2100J, manufactured by Prime Polymer) and cellulose (trade name: UFC-100, manufactured by Rettenmeier) The mixture was kneaded so that the mass ratio was 30:70 (mass%: mass%), and an attempt was made to produce a pellet of a composite material composed of high-density polyethylene and cellulose. The setting conditions at this time were a resin temperature of 175 ° C. and a screw rotation speed of 100 rpm when the melt-kneaded resin was discharged.
As a result, extrusion failure occurred during pellet processing, and the pellet could not be produced.
The results are shown in Table 2.

[Comparative Example 4]
Using the same biaxial kneading extruder as in Example 1, linear low density polyethylene (LLDPE, trade name: Neozex 40300J, manufactured by Prime Polymer Co., Ltd.) and cellulose (trade name: UFC-100, manufactured by Rettenmeier) ) In a mass ratio of 30:70 (mass%: mass%) to produce composite material pellets composed of low density polyethylene and cellulose. The setting conditions at this time were such that the resin temperature when the melt-kneaded resin was discharged was 170 ° C. and the screw rotation speed was 100 rpm.
The obtained pellet was not burnt and had a normal shape.
When the extrusion melting temperature was set to 165 ° C. using this composite material pellet and extrusion blow molding was performed, the blowability of the extruded parison was poor and the moldability was partially broken, and the blow molding could not be performed normally. .

In Table 2, when the pellet was processed normally, the pellet processability was indicated as “◯”, and when the pellet was not processed normally, the pellet processability was indicated as “x”.
In Table 2, when extrusion blow molding was performed, extrusion blow moldability was indicated as “◯”, and when extrusion blow molding was not possible, extrusion blow moldability was indicated as “x”.
From the results of Table 2, in Example 1 using the low melting point PP, good results were obtained in pellet processability and extrusion blow moldability.
On the other hand, when materials other than the low melting point PP were used, good results were not obtained in pellet processability or extrusion blow moldability.

[Example 2]
Inner layer composed of low melting point PP (trade name: WINTEC WMX03, manufactured by Nippon Polypro Co., Ltd.) / Intermediate layer composed of composite material prepared in Example 1 / Outer layer composed of low melting point PP (trade name: WINTEC WMX03, manufactured by Nippon Polypro Co., Ltd.) The tube-shaped parison that is heated and melted at 160 to 180 ° C. is extruded, the tube-shaped parison is sandwiched between blow molding dies, air is blown into the interior while the parison is heated, and the extrusion is performed. By carrying out blow molding, a cellulose-containing container comprising a container body composed of a three-layer structure of an inner layer of 136 μm thickness / an intermediate layer of 949 μm thickness / an outer layer of 246 μm thickness was obtained.
The results are shown in Table 3.

In Table 3, when multilayer extrusion blow molding was performed, the multilayer extrusion blow moldability was indicated as “◯”.
From the results of Table 3, in Example 2 using the low melting point PP, good results were obtained in the multilayer extrusion blow moldability.
Further, in Example 2 where the container body is composed of an inner layer made of low-melting point PP / an intermediate layer made of the composite material prepared in Example 1 / an outer layer made of low-melting point PP, the woody odor is suppressed more than in Example 1. It was confirmed.

 INDUSTRIAL APPLICABILITY The present invention prevents appearance defects and bad odors from being generated due to heat during molding of a composite material containing cellulose, and enables molding by blow molding.

DESCRIPTION OF SYMBOLS 1 Cellulose containing container 2 Container main body 10 Cellulose containing container 11 Inner layer 12 Middle layer 13 Outer layer 14 Container main body

Claims (1)

A container body formed by melt molding a composite material containing cellulose and polypropylene,
The container body has a three-layer structure of inner layer / intermediate layer / outer layer,
The inner layer and the outer layer are composed of the polypropylene, the intermediate layer is composed of the composite material,
The polypropylene has a melting start temperature of 90 ° C. or lower, a melting peak temperature of 140 ° C. or lower, and a melting enthalpy of 80 mJ / mg or lower as measured by a differential scanning calorimeter (DSC).
A cellulose-containing container, wherein the cellulose content is 50% by mass or more.

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