JP7237630B2 - Resin composition, resin molded product, and method for producing resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a resin composition that has a low environmental load when discarded, and various resin molded products such as daily necessities, kitchen utensils, office utensils, interior goods, and civil engineering and construction materials formed from the resin composition. It is.

BACKGROUND ART Various synthetic resins are widely used as raw materials for manufacturing various products such as daily necessities, kitchen utensils, office utensils, interior utensils, and materials for civil engineering and construction. For example, packaging bags made of synthetic resin films are often used as packaging materials for packaging and containing various liquids and powders such as foods, medicines and cosmetics (Patent Document 1).

On the other hand, in recent years, _CO2 emitted when burning discarded synthetic resin has become an environmental problem. It is difficult to say that the environmental load at the time of disposal is small because it sometimes emits a large amount of CO ₂ . Therefore, as in Patent Document 2, a wood material such as bamboo, which has a carbon-neutral property (a property that does not affect the increase or decrease of CO ₂ in the atmosphere even when burned), is added to the synthetic resin that is the main raw material. Techniques for producing synthetic resin films from resin compositions have also been developed.

JP 2017-88180 A JP 2016-23282 A

However, conventional wood-containing synthetic resin films such as those disclosed in Patent Document 2 are manufactured by simply adding particles made of bamboo to synthetic resin, which is the main raw material. There are problems such as poor compatibility, easy occurrence of voids and cracks in the molded product, and poor dispersibility of the wood particles in the synthetic resin, which makes it difficult to express the original characteristics of the synthetic resin.

The object of the present invention is to solve the problems of the resin composition, which is the raw material for forming the conventional resin molded product, and to contain a substance having carbon-neutral properties, so that the environmental load at the time of disposal of the molded product is reduced. To provide a resin composition that, despite its small size, has good compatibility with synthetic resin, does not easily form voids and cracks during molding, and can be molded into a molded product that exhibits the inherent characteristics of synthetic resin. to provide. Another object of the present invention is to provide a molded article formed from the resin composition that has a small environmental impact when discarded and that can exhibit the inherent properties of the synthetic resin.

Among the present invention, the invention described in claim 1 is a resin composition obtained by mixing a synthetic resin and particles of a plant-derived material, wherein the synthetic resin is a polyolefin resin, and the plant-derived material are acetylated bean husk particles, and the mixing ratio of the bean husk particles and the polyolefin resin represented by the following formula 1 is 10% or more and 70% or less . .
(Mixing ratio of bean husk particles and polyolefin resin) = (mass of bean husk particles) / [(mass of bean husk particles) + (mass of polyolefin resin)] Formula 1

The invention described in claim 2 is the invention described in claim 1, characterized in that the mixing ratio of the bean shell particles and the polyolefin resin is 10% or more and 30% or less. .

The invention described in claim 3 is the invention described in claim 1 or claim 2, using a method in accordance with JIS K6921-1 at a temperature of 190°C, a load of 2.16 kg, and a unit of g/10 min. The melt flow rate (MFR) measured under the conditions of is adjusted to 5 or more and 25 or less.

The invention recited in claim 4 is characterized in that, in the invention recited in any one of claims 1 to 3, the average particle diameter of the bean husk particles is 5 μm or more and 200 μm or less.

The invention recited in claim 5 is characterized in that, in the invention recited in any one of claims 1 to 3, the average particle diameter of the bean husk particles is 50 μm or more and 3 mm or less.

The invention recited in claim 6 is the invention recited in any one of claims 1 to 5, characterized in that the polyolefin resin includes one subjected to acid modification treatment.

The invention recited in claim 7 is a spoon or fork characterized by being formed from the resin composition recited in any one of claims 1 to 3, 5, and 6 .

According to an eighth aspect of the invention, there is provided a film or sheet formed of the resin composition according to any one of the first to fourth and sixth aspects .

The invention according to claim 9 is a method for producing the resin composition according to any one of claims 1 to 6, wherein a drying step of drying the bean paste husk particles and the bean paste dried by the drying step It is characterized by having a surface treatment step of acetylating the shell particles, and a kneading step of adding the acetylated bean paste husks acetylated by the surface treatment step to the melted polyolefin resin and kneading them. .

Since the resin composition according to the present invention contains particles of bean paste husks, which are a plant-derived material having carbon-neutral properties, the environmental impact when discarding the molded article is small. In spite of this, because the bean husk particles and the synthetic resin blend well, there are few voids and cracks, and a molded product that can express the original characteristics of polyolefin resin (high strength, rigidity, etc.) can be molded. be able to. Furthermore, the resin composition according to the present invention can impart a unique texture and texture derived from bean hulls to a molded product. Therefore, the resin composition according to the present invention can be widely used in various applications such as synthetic resin films, tableware, spoons, forks and other daily necessities, kitchen utensils, office utensils, interior utensils, and materials for civil engineering and construction. can.

In addition, since the spoon and fork according to the present invention have a unique texture and texture derived from bean paste husks, they can be suitably used as eating utensils for Japanese cuisine. and other characteristics are not impaired, it is less likely to be damaged and can be used for a long period of time. Furthermore, the spoon and fork according to the present invention can provide a unique and smooth texture derived from bean paste husks when used.

On the other hand, the film/sheet according to the present invention has a unique texture and texture derived from bean husks, and exhibits a color different from that of ordinary synthetic resin films/sheets. can also express good designability. Furthermore, since the film or sheet according to the present invention does not lose the high strength, rigidity, and other properties inherent in polyolefin resins, it is less likely to break and can be used for a long period of time.

On the other hand, according to the method for producing a resin composition according to the present invention, a resin composition that can be molded into a molded product that has a small environmental impact when the molded product is discarded and that can exhibit the inherent characteristics of polyolefin resin is It can be manufactured efficiently in a short time.

It is explanatory drawing which shows the manufacturing process of a resin composition.

Preferred embodiments of the present invention are described in detail below. In the following description, "~" in relation to the properties, content, and addition amount of each component basically means the numerical value on the left side or more and the numerical value on the right side or less.

The resin composition according to the present invention is obtained by adding bean paste, which is a plant-derived material, in a predetermined proportion to a polyolefin resin. The polyolefin-based resin referred to here is a resin mainly composed of polyolefin having a polyolefin ratio of approximately 80% by mass. Polypropylene, medium-density polyethylene, and high-density polyethylene can be used alone as the polyolefin, or two or more of them can be used in combination. In addition, as the polyolefin-based resin, if a graft-modified polyolefin such as maleic acid-modified polyethylene or maleic acid-modified polypropylene is used alone or a mixture of two or more of them is used, the polyolefin in the resin composition It is preferable because the affinity (compatibility) between the system resin and the particles of the bean paste husk becomes good, and voids and cracks are less likely to be formed when molding the molded product. As a combination of two or more resins, a non-modified resin and a maleic acid-modified resin can be kneaded, which is preferable from the viewpoint of strength and cost. For example, modified polypropylene and maleic acid modified polypropylene can be mixed, and the mixing ratio can be 1:10 to 10:1, preferably 1:3 to 3:1.

In addition, the bean husk as used in the present invention refers to the seed coat portion of adzuki beans, kidney beans, etc., and is removed when producing bean paste from adzuki beans and kidney beans (beans for white bean paste). Bean skins can be preferably used. In order to add the bean paste husks to the polyolefin resin, it is necessary to pulverize the bean paste husks into particles using a pulverizing device such as a classifying pulverizer.

The size of the bean paste husk particles is not particularly limited, but when the resin composition is used as a raw material for molding three-dimensional molded products such as eating utensils such as tableware, spoons and forks, kitchen utensils, and interior utensils. Therefore, adjusting the average particle size (particle diameter) to 50 μm to 3 mm facilitates the preparation of the resin composition and does not impair the properties of the molded product (that is, the original strength and rigidity of the polyolefin resin). It is preferable because it makes it easier to give the texture and texture peculiar to the bean husk to the molded product.

On the other hand, when the resin composition is used as a raw material for molding a two-dimensional molded product such as a film or sheet, voids and cracks can be prevented by adjusting the average particle size (particle diameter) to 5 to 200 μm. It is preferable because it is possible to obtain a film, a sheet, or the like capable of exhibiting the original strength and rigidity of the polyolefin resin. The particle diameter can be obtained by microscopic image analysis as the number average diameter, and the average value of the diameters of 100 particles (longer diameter if the particles are not circular) can be adopted. In addition, when using particles whose surface has been acetylated (immersion treatment in acetic acid, etc.) as the bean paste shell particles, the compatibility with polyolefin resin is further improved, and voids and cracks in the molded product are improved. It is preferable because it becomes more difficult to do. In addition, as the main raw material of the resin composition according to the present invention, when using a normal polyolefin-based resin instead of using an acid-modified polyolefin-based resin such as maleic acid-modified polyethylene or maleic acid-modified polypropylene, bean shell It is essential in the preparation of the resin composition to use particles whose surfaces are acetylated.

Also, the method for preparing the bean paste husk particles is not particularly limited, but it is preferable to employ a method of pulverizing after drying, since particles with a small variation in particle size can be obtained. FIG. 1 shows an example of a method for preparing bean paste husk particles that employs such a method of pulverizing after drying. In such a preparation method, after the primary drying treatment _T1 in which the bean paste husks are dried at a predetermined temperature (about 60 to 150 ° C.) for a predetermined time (1 hour to 3 days), the bean husks are coarsely pulverized (the average particle size is Coarse pulverization treatment _T2 for pulverizing to about 3 mm to 5 mm) is performed, and acetylation treatment (surface treatment) _T3 for acetylating the bean hulls is further performed. Furthermore, after the acetylation treatment (surface treatment) T ₃ , a secondary drying treatment T ₄ is performed to dry the bean hulls at a predetermined temperature (about 60 to 150° C.) for a predetermined time (1 to 10 hours). Afterwards, a fine pulverization treatment _T5 is performed to finely pulverize the bean paste hulls (pulverize them to an average particle size of about 5 μm to 3 mm). In the coarse pulverization process _T2 and the fine pulverization process _T5 , it is possible not only to simply finely crush particles, but also to remove (classify) large particles. Such a preparation method in which acetylation treatment _T3 is carried out after coarse pulverization treatment _T2 and then fine pulverization treatment _T5 is carried out is particularly preferable because particles with extremely small variations in particle size can be obtained. In addition, the adjustment method described above can omit some steps, for example, the acetylation step of _T3 can be omitted. In addition, a step of squeezing and removing water from the bean hulls may be provided before the primary drying step of _T1 .

On the other hand, the bean paste husk particles should be contained at a rate of 1 to 70% by mass with respect to the polyolefin resin (the entire raw material). If the content (addition amount) of the bean paste husk particles is less than 1%, the unique texture of the bean paste husk cannot be expressed, which is not preferable. On the other hand, if the content of the bean husk particles exceeds 70%, the inherent properties of the polyolefin resin become difficult to manifest, and phenomena such as reduced strength and rigidity of the molded product tend to occur, which is undesirable. The content of bean paste husk particles is more preferably 2% or more and 30% or less, and particularly preferably 5% or more and 20% or less. In addition, the resin composition made of the polyolefin resin to which the bean paste husk particles have been added forms a molded product when adjusted to have a melt flow rate within the range of 5.0 or more and 25.0 or less. It is preferable because the handleability (molding processability) is improved and it becomes possible to mold efficiently, and it is more preferable that the melt flow rate is 10.0 or more and 15 or less.

In addition, the method of adding the bean husk particles to the polyolefin resin is not particularly limited. A method of polymerizing the raw material monomer after adding the particles can be preferably used. In addition, when the method of adding bean husk particles to the melted polyolefin resin is used, the dispersibility of the bean husk particles in the polyolefin resin is improved, and the resin composition has less variation in physical properties during molding. It is preferable because it is easy to obtain things.

In addition, when forming a film or sheet from the resin composition according to the present invention, a substrate layer, an adhesive layer, a sealant layer, a printing layer, a barrier layer (oxygen barrier layer, water vapor barrier layer, layer, etc.), an adhesive layer, an anchor coat layer, etc., to form a laminated film or laminated sheet.

Hereinafter, the resin composition according to the present invention, the method for producing the resin composition, and the resin molded product will be described in detail by way of examples, but the present invention is not limited to the embodiments of these examples. Modifications can be made as appropriate without departing from the gist of the present invention. Methods for evaluating physical properties and characteristics in Examples and Comparative Examples are as follows.

<Melt flow rate (MFR)>
Using a melt indexer F-F01 manufactured by Toyo Seiki Seisakusho, measurement was performed according to JIS K6921-1 under the conditions of temperature: 190° C., load: 2.16 kg, unit: g/10 min.

<Environmental impact>
Evaluated in the following two stages according to the amount of raw materials with carbon-neutral properties (properties that do not affect the increase or decrease of _CO2 in the atmosphere even when burned) contained in the resin compositions obtained in Examples and Comparative Examples. bottom.
○: The content of the raw material having carbon-neutral properties is 10% by mass or more ×: The content of the raw material having carbon-neutral properties is less than 10% by mass

<Appearance design (texture)>
The design properties of the resin molded articles (synthetic resin films and spoons) obtained in the examples and comparative examples were visually evaluated sensorily in the following three grades.
◎: It has a unique texture and texture that is different from ordinary resin molded products (such as those produced from plant-derived materials), and the surface is matte, so it is almost non-sticky ○: Slight texture and texture In addition, the surface is slightly matted, and it does not dry out much.

<Surface tactile sensation>
The tactile sensation of the surfaces of the resin molded articles (synthetic resin films and spoons) obtained in Examples and Comparative Examples was sensory evaluated in the following three stages.
◎: Strong sense of rough texture peculiar to bean paste shells (appropriate unevenness and smoothness)
○: A rough texture peculiar to bean shells is felt △: No tactile sensation other than that of resin (it is not smooth and feels like a fingertip is caught)

<Tensile strength>
The synthetic resin films produced in Examples 1 to 4 and Comparative Example 2 were sampled in a length of 150 mm and a width of 15 mm, and the humidity was conditioned for 24 hours in an atmosphere of 23° C. and 50% relative humidity. After that, under the conditions of a temperature of 23 ° C. and a relative humidity of 50%, in accordance with JIS K-7127, using an Autograph AG-100E manufactured by Shimadzu Corporation, a humidity-conditioned synthetic resin film was placed at a distance of 100 mm. It was held between two chucks and pulled at a tensile speed of 200 mm/min, and the ratio of tensile stress within the tensile proportional limit to the corresponding strain was calculated as the tensile modulus. Then, the calculated numerical value of the tensile modulus was evaluated in the following three stages.
◎: 2.0 GPa or more ○: 1.0 GPa or more and less than 2.0 GPa △: less than 1.0 GPa

[Example 1]
<Production of bean paste husk particles>
Bean hulls (skins of red beans after boiling which are removed when producing red bean paste from red beans) were squeezed to remove moisture, and then dried at 80° C. for 3 hours. Thereafter, the dried bean paste hulls were coarsely pulverized by a classifying pulverizer so that the average particle size (number average particle size) was about 3 mm. Furthermore, after drying the bean paste husk particles pulverized as described above at 100° C. for 3 hours, they are pulverized and classified again by a classifying pulverizer so that the average particle size (number average particle size) is 10 μm. Bean husk particles (average particle size = 10 µm) were thus obtained.

<Preparation of resin composition>
Maleic acid-modified polypropylene, which is a modified polyolefin resin, is melted at about 200° C., and 60% by mass of the bean shell particles (number average particle diameter=10 μm) are added to the molten resin to obtain a resin composition. was prepared. Then, the melt flow rate (MFR) of the obtained resin composition was measured by the method described above.

<Production of resin molded products>
As described above, the resin composition was extruded into a sheet at a temperature of 200° C. and biaxially stretched at a predetermined temperature to obtain a synthetic resin film having a thickness of 100 μm. Then, the properties of the synthetic resin film were evaluated by the methods described above. Table 1 shows the evaluation results of the properties of the synthetic resin film of Example 1 together with the properties of the resin composition.

[Example 2]
A 1:1 mixture of polyethylene resin and maleic acid-modified polypropylene, which is a modified polyolefin resin, is melted at about 200° C. In the molten resin, bean shell particles obtained in the same manner as in Example 1 (number average A resin composition of Example 2 was prepared by adding 10% by mass of 10% by mass of a particle size of 10 μm. Then, the melt flow rate of the obtained resin composition was measured by the method described above. Further, a synthetic resin film having a thickness of 100 μm was obtained in the same manner as in Example 1 using the resin composition obtained in Example 2. Then, the properties of the synthetic resin film were evaluated by the methods described above. Table 1 shows the evaluation results of the properties of the synthetic resin film of Example 2 together with the properties of the resin composition.

[Example 3]
Bean husk particles were obtained in the same manner as in Example 1, except that the average particle size (number average particle size) of the bean paste husk particles was adjusted to 100 μm. Then, the bean husk particles (number average particle size = 100 µm) were melted at about 200 ° C. and added to the same modified polyolefin resin (maleic acid-modified polypropylene) as in Example 1 at 50% by mass. was prepared, and the melt flow rate of the resulting resin composition was measured by the method described above. Further, a synthetic resin film having a thickness of 100 μm was obtained in the same manner as in Example 1 using the resin composition obtained in Example 3. Then, the properties of the synthetic resin film were evaluated by the methods described above. Table 1 shows the evaluation results of the properties of the synthetic resin film of Example 3 together with the properties of the resin composition.

[Example 4]
After coarsely pulverizing the bean paste husk particles in the same manner as in Example 1, the bean husk particles were immersed in 1N acetic acid at a temperature of 25° C. to acetylate the surface of the bean paste husk particles. After drying the hardened bean husk particles at 100 ° C. for 3 hours, the bean husks are re-pulverized and classified by a classifying grinder so that the average particle size (number average particle size) is 10 μm. Particles were obtained. Then, 50% by mass of the bean paste husk particles (number average particle size = 10 µm) was added to a polyolefin resin (polypropylene) melted at about 200 ° C. to prepare a resin composition of Example 4. The melt flow rate of the resulting resin composition was measured by the method described above. Further, a synthetic resin film having a thickness of 100 μm was obtained in the same manner as in Example 1 using the obtained resin composition of Example 4. Then, the properties of the synthetic resin film were evaluated by the methods described above. Table 1 shows the evaluation results of the properties of the synthetic resin film of Example 4 together with the properties of the resin composition.

[Example 5]
Bean husk particles (number average particle size = 100 µm) obtained in the same manner as in Example 3 were melted at about 200 ° C. and added to the same modified polyolefin resin (maleic acid-modified polypropylene) as in Example 1. The resin composition of Example 5 was prepared by adding and the melt flow rate of the resulting resin composition was measured by the method described above. Further, using the obtained resin composition of Example 5, injection molding was performed at a temperature of 200 ° C. to obtain a spoon as a resin molded product (length of the grip part x maximum width x thickness of 180 mm x 10 mm x 2.0 mm and the storage capacity is 10 cc). The properties of the spoon were then evaluated by the methods described above. Table 1 shows the evaluation results of the properties of the spoon of Example 5 together with the properties of the resin composition.

[Example 6]
Bean husk particles were obtained in the same manner as in Example 1, except that the average particle size (number average particle size) was adjusted to 3 mm (= 3,000 µm) in the preparation of the bean husk particles. Then, the bean husk particles (number average particle size = 3,000 µm) were melted at about 200 ° C. and added 20% by mass to the same modified polyolefin resin (maleic acid-modified polypropylene) as in Example 1. The resin composition of Example 6 was prepared and the melt flow rate of the resulting resin composition was measured by the method described above. Moreover, a spoon was formed in the same manner as in Example 5 using the obtained resin composition of Example 6. The properties of the spoon were then evaluated by the methods described above. Table 1 shows the evaluation results of the properties of the spoon of Example 6 together with the properties of the resin composition.

[Comparative Example 1]
A resin composition of Comparative Example 1 was prepared and obtained in the same manner as in Example 1, except that the amount of bean paste husk particles added to the modified polyolefin resin (maleic acid-modified polypropylene) was changed to 80% by mass. The melt flow rate of the resin composition was measured by the method described above. Also, using the obtained resin composition of Comparative Example 1, an attempt was made to form a synthetic resin film having a thickness of 100 μm by the same method as in Example 1. I couldn't do it.

[Comparative Example 2]
The same modified polyolefin resin (maleic acid-modified polypropylene melt flow rate = 20) as in Example 1 was extruded into a sheet at a temperature of 200°C, and biaxially stretched at a predetermined temperature to form a synthetic resin film having a thickness of 100 µm. got Then, the properties of the synthetic resin film were evaluated by the methods described above. Table 1 shows the evaluation results of the properties of the synthetic resin film of Comparative Example 2 together with the properties of the resin composition.

[Comparative Example 3]
Bean husk particles (number average particle size = 100 µm) obtained in the same manner as in Example 3 were melted at about 200 ° C. and added to the same modified polyolefin resin (maleic acid-modified polypropylene) as in Example 1. A resin composition of Comparative Example 3 was prepared by adding the above, and the melt flow rate of the resulting resin composition was measured by the method described above. Also, an attempt was made to form a spoon having the same shape as in Example 5 by injection molding the obtained resin composition of Comparative Example 3 at a temperature of 200° C., but the resin composition was fragile. It was not possible to form a tall, usable spoon.

[Comparative Example 4]
A spoon was formed in the same manner as in Example 5 using the same modified polyolefin resin (maleic acid-modified polypropylene melt flow rate=20) as in Example 1. The properties of the spoon were then evaluated by the methods described above. Table 1 shows the evaluation results of the properties of the spoon of Comparative Example 4 together with the properties of the resin composition.

From Table 1, it can be seen that all of the resin compositions of Examples 1 to 6 not only have a small environmental burden when discarding molded articles, but also have good moldability. In addition, the films formed from the resin compositions of Examples 1 to 4 have a texture, texture, and touch unique to bean husks, and are excellent in designability. It can be seen that the tensile strength is about the same as that of polyolefin resin. On the other hand, the spoons molded from the resin compositions of Examples 5 and 6 have the texture, texture, and tactile sensation peculiar to bean paste shells, and are found to be excellent in design.

On the other hand, the resin compositions of Comparative Examples 1 and 3 have a small environmental load when discarding the molded products, but the moldability is poor, and the resin compositions of Comparative Examples 2 and 4 are discarded. It can be seen that the environmental load is large when doing so, and the design is poor.

Since the resin composition according to the present invention exhibits excellent effects as described above, it can be suitably used as a raw material for molding various resin moldings. In addition, resin molded articles formed from the resin composition can be suitably used for various applications such as daily necessities, kitchen utensils, office utensils, interior utensils, civil engineering and construction materials, and the like.

Claims (9)

A resin composition obtained by mixing a synthetic resin and particles of a plant-derived material,
The synthetic resin is a polyolefin resin, and the particles of the plant-derived material are acetylated bean shells,
A resin composition characterized in that the mixing ratio of bean paste husk particles represented by the following formula 1 and a polyolefin resin is 10% or more and 70% or less.
(Mixing ratio of bean husk particles and polyolefin resin) = (mass of bean husk particles) / [(mass of bean husk particles) + (mass of polyolefin resin)] Formula 1 2. The resin composition according to claim 1, wherein the mixing ratio of the bean paste husk particles and the polyolefin resin is 10% or more and 30% or less. A claim characterized in that the melt flow rate measured under the conditions of temperature: 190°C, load: 2.16 kg, and unit: g/10 min by a method in accordance with JIS K6921-1 is adjusted to 5 or more and 25 or less . 3. The resin composition according to claim 1 or 2. 4. The resin composition according to any one of claims 1 to 3, wherein the average particle size of the bean paste husk particles is 5 µm or more and 200 µm or less. 4. The resin composition according to any one of claims 1 to 3, wherein the average particle size of the bean paste husk particles is 50 µm or more and 3 mm or less. 6. The resin composition according to any one of claims 1 to 5, wherein the polyolefin resin includes an acid-modified resin. A spoon or fork characterized by being formed from the resin composition according to any one of claims 1 to 3, 5 and 6 . A film or sheet formed of the resin composition according to any one of claims 1 to 4 and 6 . A method for producing a resin composition according to any one of claims 1 to 6 ,
A drying step of drying the bean paste husk particles,
a surface treatment step of acetylating the dried bean paste husk particles in the drying step ;
and a kneading step of adding the bean paste hulls acetylated by the surface treatment step to a melted polyolefin resin and kneading them.

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