JP6959629B2 - Injection molding container - Google Patents

Description

The present invention relates to an injection molded container.

Conventionally, as a container for medicines such as liquids and creams, quasi-drugs, cosmetics, etc., a tube container having a head composed of a mouth and shoulders and a body connected to the shoulders has been used. It is used.
Such a tube container is manufactured by extrusion molding from the viewpoint that a container having a desired shape can be easily formed.

As such an extrusion-molded tube container, a resin container derived from fossil fuel such as a polyolefin resin is mainly used from the viewpoint of ease of molding, cost, physical properties and the like.

Since the resin derived from the fossil fuel is specifically produced from fossil fuels such as oil, coal, and natural gas, fossils have been used for the purpose of suppressing an increase in the amount of _{CO 2 in the atmosphere in recent years.} Research is being actively conducted on the use of biomass-derived resins as a substitute for fuel-derived resins.

For example, as a tube container using a biomass-derived resin, Patent Document 1 discloses a tube container made of a resin composition containing a biomass-derived polyolefin obtained by polymerizing a monomer containing biomass-derived ethylene. There is. However, Patent Document 1 does not substantially disclose a tube container using low-density polyethylene derived from biomass having a relatively high melt flow rate.

Japanese Unexamined Patent Publication No. 2015-96431

In the tube container described in Patent Document 1, it is described that the head is formed by injection molding or the like using a composition containing a biomass-derived polyolefin, but it cannot be said that the injection moldability is good. ..

As the tube container, a container manufactured by injection molding is also known. The injection molded tube is formed by using a predetermined mold to form a molded body having a head portion including a mouth portion and a shoulder portion and a body portion connected to the shoulder portion, and then the head side of the body portion is formed. Formed by sealing the opposite end. It was found that in such an injection molded tube, cracks were generated in the end seal portion at an initial stage, and the cracks grew and led to leakage of the contents.
In particular, it was found that injection molding is difficult and cracks are likely to occur in an injection molded tube container having a body thickness of 0.8 mm or less and a body length of 10 cm or more.

The conventional injection-molded container does not have sufficient injection-molding property, and in particular, stress-cracking resistance (hereinafter, also referred to as “stucking resistance”) is not sufficient.
The present invention has been made in view of the above problems, and an object of the present invention is to provide an injection-molded container having excellent injection-molding property and stock-molding resistance.

As a result of diligent research to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by using a container containing low-density polyethylene derived from a specific biomass, and have completed the present invention.
A configuration example of the present invention is as follows.

[1] Containing low density polyethylene (A) derived from biomass and having a melt flow rate in the range of 20-50 g / 10 min measured under the conditions of 190 ° C. and 21.18 N load according to ASTM D1238, and
The weight ratio of the biomass-derived resin represented by the following formula (1) is 60 to 100%.
Injection molded container.
Weight ratio of biomass-derived resin = Weight of biomass-derived resin used to manufacture the container x Biomass degree (%) of the resin / Total weight of resin used to manufacture the container ... (1)

[2] The container according to [1], wherein the container is an injection molded tube container.
[3] The container is a tube container including a head portion including a mouth portion and a shoulder portion and a body portion connected to the shoulder portion.
The container according to [1] or [2], which is an injection-molded tube container in which the head and the body are integrally molded.
[4] The container according to [3], wherein the body has a thickness of 0.5 to 0.8 mm.

[5] The container according to any one of [1] to [4], further containing an ethylene-based elastomer (B).

[6] Of [1] to [5], further comprising low density polyethylene (C) having a melt flow rate of 50 to 150 g / 10 min as measured according to JIS K 6922-1 (190 ° C., 21.18N). The container described in either.

According to the present invention, a container having excellent injection moldability and stocking resistance can be easily obtained.
In particular, according to the present invention, it is easy to obtain an injection-molded tube container having an excellent injection moldability and stocking resistance while having a body thickness of 0.8 mm or less and a body length of 10 cm or more. Can be obtained.

FIG. 1 is a schematic view showing an example of a side view of a container (tube container) according to the present invention.

≪Container≫
The container according to the present invention (hereinafter, also referred to as “the present container”) has a melt flow rate (MFR) of 20 to 50 g measured under the conditions of 190 ° C. and 21.18 N (2.16 kg) load according to ASTM D1238. Contains low-density polyethylene (A) derived from biomass (hereinafter, also referred to as "component (A)"; the same applies to other resins) in the range of / 10 minutes, and
The weight ratio of the biomass-derived resin represented by the following formula (1) is 60 to 100%.
Weight ratio of biomass-derived resin = Weight of biomass-derived resin used to manufacture the container x Biomass degree (%) of the resin / Total weight of resin used to manufacture the container ... (1)
As a result of diligent studies by the present inventor, it is not clear why the biomass-derived low-density polyethylene having a relatively high MFR is used and the weight ratio of the biomass-derived resin is within the above range. It was found that an injection-molded container having excellent injection moldability and particularly excellent biomass resistance can be obtained.

The container is not particularly limited, but is more preferably an injection-molded tube container from the viewpoint of more effectively exerting the effects of the present invention.
As shown in FIG. 1, the injection-molded tube container is usually a tube container including a head portion including a shoulder portion 3 and a mouth portion 1 and a body portion 2 connected to the shoulder portion 3.

The thickness of the body portion may be appropriately selected depending on the desired application, but is preferably 0.8 mm or less, more preferably 0.5, from the viewpoint that the significance of using the component (A) is more exhibited. It is ~ 0.8 mm, particularly preferably 0.6 ~ 0.7 mm.
By using the component (A), an injection-molded tube container having such a thickness can be easily formed, and even if the body portion has such a thickness, injection-moldability and anti-stracula resistance can be easily formed. An injection-molded tube container having excellent properties can be obtained.

Further, the length of the body portion may be appropriately selected depending on the desired application, but is preferably 10 cm or more, more preferably 11 to 20 cm, from the viewpoint that the significance of using the component (A) is more exhibited. Especially preferably, it is 14 to 16 cm.
By using the component (A), an injection-molded tube container having such a length can be easily formed, and even if the body has such a length, injection-moldability and anti-stracula resistance can be easily formed. An injection-molded tube container having excellent properties can be obtained.

The use of this container is not particularly limited, but it can be used for the use, storage, transportation, etc. of pharmaceuticals, quasi-drugs, cosmetics, foods, building / civil engineering / agricultural materials, etc., such as liquids and creams. More preferably, there are applications such as using, storing, and transporting liquid foundations, creams, facial cleansing foams, and the like.

<Low density polyethylene derived from biomass (A)>
The present container is characterized by containing low-density polyethylene (A) derived from biomass, and may be a container substantially composed of only the polyethylene (A).
By using such polyethylene (A), it is _{preferable not only to suppress an increase in the amount of CO 2} in the atmosphere and to save petroleum resources, but also to easily obtain an injection-molded container having excellent stocking resistance. Can be done.
The polyethylene (A) contained in this container may be one type alone or two or more types.

The mass of the biomass-derived resin and the mass of the fossil fuel-derived resin ^{can be distinguished by the ratio of 14} C contained, and specifically, by ASTM-D6866-12. Is.

According to ASTM D1238 of polyethylene (A), the MFR measured under the condition of 190 ° C. and 21.18 N load is 20 to 50 g / 10 minutes, which makes it easy to obtain an injection molded container having excellent injection moldability and stockability resistance. From the viewpoint of being able to be obtained, it is preferably 20 to 40 g / 10 minutes, and more preferably 20 to 30 g / 10 minutes.

The density measured according to JIS K 7112 of polyethylene (A) is preferably 0.91 to ^{0.94 g / cm 3 and more preferably 0.91 from the viewpoint of obtaining a container having particularly excellent flexibility.} ~ 0.93 g / cm ³ .

The biomass is not particularly limited, but sugar cane (including bagasse), corn, starch, castor oil, crushed tatami mats (used waste tatami mats), wood chips, wood flour, sawdust, paper scraps, vegetation sorghum, and squeezed straw vegetables. Examples include vegetation such as bagasse and rice straw, coniferous tree materials, broadleaf tree materials, non-tree materials, and wastes of these materials.

The low-density polyethylene derived from biomass in the present invention is not particularly limited as long as it is a low-density polyethylene obtained from ethylene derived from biomass as a raw material, but specifically, alcohol obtained by fermenting a plant is used as a raw material. Examples thereof include plant-derived low-density polyethylene using synthetic ethylene.
More specifically, a conventionally known method is used to ferment a sugar solution or starch obtained from the biomass with a microorganism such as yeast to produce bioethanol, which is heated in the presence of a catalyst to carry out an intramolecular dehydration reaction. Using ethylene obtained by equalization and, if necessary, α-olefin (eg, 1-butene, 1-hexene) as a monomer, so-called Ziegler-Natta catalyst, etc., as in the synthesis of low-density polyethylene derived from fossil fuels, etc. Examples thereof include low-density polyethylene obtained by (co) polymerization by a high-pressure method using the above method, a polymerization method using a metallocene catalyst, or the like.

As the copolymer, in addition to the biomass-derived α-olefin, a fossil fuel-derived comonomer generally used in the synthesis of low-density polyethylene may be used. Specifically, it may be low-density polyethylene obtained by polymerizing a mixed monomer containing ethylene as a main component and α-olefin as a sub-component in the presence of a metallocene catalyst or the like. As the α-olefin, one or more α-olefins having 3 to 40 carbon atoms, preferably 4 to 35 carbon atoms, more preferably 4 to 30 carbon atoms are used, and for example, α-olefins having 3 to 8 carbon atoms are used. Can be used in combination with an α-olefin having 10 to 26 carbon atoms. When the low density polyethylene is a copolymer, the content of α-olefin is preferably 3 to 15 mol% with respect to the copolymer.

As the polyethylene (A), it may be obtained by synthesizing it by the above-mentioned method or the like, or a commercially available product may be used.

The content of polyethylene (A) with respect to 100% by weight of the total resin component contained in this container is preferably 70 to 70 to obtain an injection-molded container having an excellent balance due to injection moldability and stocking resistance. It is 100% by weight, more preferably 80 to 100% by weight, and particularly preferably 90 to 100% by weight.

The weight ratio of the biomass-derived resin represented by the following formula (1) _{suppresses the increase in the amount of CO 2 in} the atmosphere and also leads to the saving of petroleum resources. It is 60 to 100%, preferably 75 to 100%, and more preferably 85 to 100% from the viewpoint that a container can be easily obtained.
Weight ratio of biomass-derived resin = Weight of biomass-derived resin used to manufacture the container x Biomass degree (%) of the resin / Total weight of resin used to manufacture the container ... (1)

When two types of biomass-derived resins (resin (a) and resin (b)) are used as raw materials for this container, the above formula (1) is as shown in the following formula (1'). The same applies when three or more types of biomass-derived resins are used.
Weight ratio of resin derived from biomass = (weight of resin (a) x biomass degree (%) of resin (a) + weight of resin (b) x biomass degree (%) of resin (b)) / Production of the container Total weight of resin used in ... (1')

The biomass degree of the resin is the total weight of the biomass-derived raw material monomers used when synthesizing the resin with respect to the total weight of the raw material monomers used when synthesizing the resin.

<Ethylene elastomer (B)>
The present container may contain an ethylene-based elastomer (B) from the viewpoint that an injection-molded container having excellent flexibility, transparency and low-temperature sealing property can be easily obtained.
When the present container contains an elastomer (B), the elastomer (B) may be used alone or in combination of two or more.

The elastomer (B) is preferably an ethylene / α-olefin copolymer, and more preferably an ethylene / α-olefin random copolymer. Examples of the ethylene / α-olefin copolymer include a copolymer of ethylene and one or more types of α-olefin having 3 to 20 carbon atoms, preferably 3 to 10 carbon atoms.
The α-olefin content in the copolymer is usually 3 to 39 mol%, preferably 5 to 30 mol%, and more preferably 5 to 25 mol% with respect to the copolymer.

Specific examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 4-methylpentene-1, 1-octene, 1-decene, and 1-dodecene. However, among these, propylene, 1-butene, 1-hexene, and 1-octene are preferable.

Further, if necessary, a small amount of other dienes such as comonomer 1,6-hexadiene, 1,8-octadien, and cyclic olefins such as cyclopentene may be used.

Ethylene and α-olefins used in the synthesis of elastomer (B) _{suppress the increase in the amount of CO 2 in} the atmosphere and also lead to the saving of petroleum resources. It is preferable to use ethylene or α-olefin derived from biomass from the viewpoint that a molded container can be easily obtained.

As the elastomer (B), a resin compatible with polyethylene (A), and polyethylene (A) and (C) It is preferable to use a compatible resin.

The MFR (230 ° C., 21.18N) measured according to ASTM D1238 of the elastomer (B) is preferably 5 to 70 g / 10 minutes, more preferably 5 to 70 g / 10 minutes, particularly from the viewpoint of obtaining a composition having excellent injection moldability. 50-70 g / 10 minutes.

Density measured in accordance with ASTM D1505 elastomer (B) is in terms of such an injection molded container excellent in especially flexibility obtained is preferably 850~900kg / m ^3, more preferably 850~880kg / m ³ ..

The elastomer (B) may be obtained by synthesizing it by a conventionally known method using a vanadium-based catalyst, a titanium-based catalyst, a metallocene-based catalyst, or the like, or a commercially available product may be used.

When the container contains an elastomer (B), the content of the elastomer (B) is superior to the total 100% by weight of the resin component contained in the container in terms of flexibility, stocking resistance and transparency. It is preferably 5 to 20% by weight from the viewpoint of obtaining the above, and more preferably 5 to 10% by weight from the viewpoint of being more excellent in injection moldability.

<Low density polyethylene (C)>
This container has excellent injection moldability, and an injection molded tube container having a body thickness and length within the above range can be easily obtained. Therefore, the melt flow rate measured according to JIS K 6922-1. It may contain low density polyethylene (C) at (190 ° C., 21.18N) at 50-150 g / 10 min.
When the present container contains polyethylene (C), the polyethylene (C) may be used alone or in combination of two or more.

The MFR of polyethylene (C) is preferably 70 to 150 g / 10 minutes, more preferably 100 to 150 g / 10 minutes.
When the MFR is in the above range, a composition having excellent injection moldability can be obtained, which is preferable. Specifically, since the resin filling property when producing an injection-molded container is improved, a container having a desired shape can be formed more easily, the choice of molding conditions is increased, and the injection-molded container is produced. The load on the mold can be reduced.

The density of polyethylene (C) measured according to JIS K 6922-1 is preferably 0.91 to 0.94 g / cm ³ from the viewpoint of obtaining an injection-molded container having particularly excellent flexibility, which is more preferable. Is 0.91 to 0.93 g / cm ³ .

Polyethylene (C) is not particularly limited in its molecular weight, melting point, etc. as long as it satisfies the above conditions of MFR, but it does not need to be melted at a higher temperature when the resin is melted and molded, and practical heat is not required. The melting point (JIS K 6922-2) is preferably 90 to 115 ° C., more preferably 95 to 110 ° C. from the viewpoint that sufficient durability can be obtained.

Polyethylene (C) may be obtained by synthesizing by a conventionally known method, preferably by high-pressure radical polymerization, or a commercially available product may be used.

The high-pressure radical polymerization is not particularly limited, and examples thereof include a method of performing polymerization under high pressure using a radical generator such as peroxide or oxygen. The conditions for the polymerization are not particularly limited, and examples thereof include conditions of a temperature of 200 to 300 ° C. and a pressure of 1,000 to 2,000 atm.
In addition, a copolymer using a small amount of vinyl acetate, ethylene acrylate or the like together with ethylene may be used in the synthesis. Further, MFR can be adjusted by using a hydrocarbon such as hydrogen, methane or ethane which is a molecular weight modifier.

Polyethylene (C) may be a low-density polyethylene derived from biomass because it suppresses an increase in the amount _{of CO 2 in the atmosphere and also leads to saving of petroleum resources.} When low-density polyethylene derived from biomass is used, an injection-molded container having excellent stocking resistance can be easily obtained.

When this container contains polyethylene (C), the content of polyethylene (C) is excellent in balance due to injection moldability and stocking resistance with respect to 100% by weight of the total resin component contained in this container. It is preferably 5 to 20% by weight, more preferably 5 to 10% by weight, from the viewpoint of obtaining the above.

<Other ingredients>
If necessary, the container may contain components other than the components (A) to (C) as long as the effects of the present invention are not impaired.

Examples of the other components include stabilizers such as thermoplastic resins, antioxidants, heat-resistant stabilizers, light-resistant stabilizers, and weather-resistant stabilizers, ultraviolet scattering agents, anti-slip agents, anti-fog agents, colorants, and dispersants. , Fillers, antistatic agents, lubricants, fabric softeners, plasticizers, processing aids.
The present container may contain each of these other components alone or in combination of two or more.

According to the present invention, a container having excellent transparency can be obtained. Such a container is preferable from the viewpoint of excellent visibility of the contents.
A colored container may be required depending on the application and from the viewpoint of design, etc. In this case, a conventionally known colorant may be used. Since this container containing no colorant is excellent in transparency, it can be a transparent container having excellent visibility of the contents, or it can be easily colored with a colorant to a desired color.

<Container manufacturing method>
This container can be manufactured by injection molding the component (A).
When the components (B) to (C) and / or the other components are blended in addition to the component (A), these blended components are mixed to form a composition, or It can be produced by injection molding the composition while forming the composition.

The method for forming the composition is not particularly limited, but each component is melted using a conventionally known device, specifically, a single-screw extruder, a twin-screw extruder, a kneader, a mixer, a two-roll mill, or the like. The kneading method is preferable.

The MFR of the composition measured based on JIS K 7210 (190 ° C., 21.18 N load) is a composition having excellent injection moldability, and an injection molded container having excellent mechanical strength such as impact resistance can be obtained. From the above points, it is preferably 20 to 50 g / 10 minutes, more preferably 20 to 40 g / 10 minutes.

The present container is preferably an injection-molded tube container in which the head and the body are integrally molded, from the viewpoint that the effects of the present invention are more exerted. In the present invention, since the component (A) is used as a raw material, the injection moldability is particularly excellent, and a tube container can be manufactured by integral molding.
By integrally molding, the step of combining the head and the body can be omitted, complicated and complicated steps are not required, the cost can be reduced, and foreign matter adheres to the head. It is preferable because quality deterioration such as a decrease in welding strength between the body and the body is unlikely to occur.

Specifically, such an integrally molded injection-molded tube container can be manufactured by the following method.
Specifically, an injection-molded tube container integrally molded by injecting the component (A) or the composition using an injection-molded mold capable of integrally forming the mouth, shoulder and body. Obtainable.

At the time of the injection, it is preferable to inject the component (A) or the composition into the cavity through at least two sprues. By using two or more sprues, the composition can be injected with a uniform pressure, so that a tube container having a desired shape can be easily obtained.

The integrally molded body of the head and the body obtained as described above can be made into a tube container by welding the end of the body opposite to the head side.
As the welding method, conventionally known welding methods such as hot air, ultrasonic welding, and heat sealing can be adopted without limitation.

In addition, if necessary, this container may be embossed for the purpose of improving design, etc., enabling small lot production, eliminating the need for printing plates, and supporting a variety of designs. From the point of view, digital printing may be performed.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

In the following tests, commercially available products having the following physical characteristics were used.
-Biomass 1: MFR (ASTM D1238, 190 ° C., 21.18N); 30.0 g / 10 min, density (JIS K 7112); 915 kg / m ³ , biomass degree 95% or more-Biomass 2: MFR (ASTM D1238, 190) ℃ 21.18N); 8.1g / 10min, density (JIS K 7112); 918kg / m ³ , biomass degree 95% or more ・ Biomass 3: MFR (ASTM D1238, 190 ℃, 21.18N); 7.2g / 10 min, density (JIS K 7112); 959 kg / m ³ , biomass degree 94% or more ・ LDPE: density (JIS K 6922-1); 915 kg / m ³ , MFR (JIS K 6922-1, 190 ° C., 21. 18N); 145g / 10min, bending elasticity (JIS K 6922-2); 90MPa
Ethylene elastomer: MFR (ASTM D1238, 230 ° C., 21.18N); 65 g / 10 min, density (ASTM D1505); 870 kg / m ³

[Example 1]
Using an injection molding die capable of integrally forming the mouth, shoulder and body, the biomass 1 is injection molded at 200 ° C. using an injection molding machine, and the end of the body opposite to the head side. Was welded at 350 ° C. to obtain an injection-molded tube container in which the head and the body were integrally molded.
The thickness of the body of the obtained injection-molded tube container was 0.7 mm, and the length was 14.5 cm.

[Examples 2 to 11 and Comparative Examples 1 to 3]
An injection-molded tube container was obtained in the same manner as in Example 1 except that the raw materials shown in Table 1 were charged into the injection molding machine in the amounts shown in Table 1 instead of the biomass 1. The unit of the numerical value in the column of raw materials in Table 1 is the part by weight.

<Weight ratio of biomass-derived resin>
The weight ratio of the biomass-derived resin was calculated according to the following formula (1). The results are shown in Table 1.
Weight ratio of biomass-derived resin = Weight of biomass-derived resin used to manufacture the container x Biomass degree (%) of the resin / Total weight of resin used to manufacture the container ... (1)

<MFR>
Using the raw materials (compositions) shown in Table 1, MFR was measured under the conditions of 190 ° C. and a load of 21.18 N based on JIS K 7210. The results are shown in Table 1.

<Filling pressure>
When forming the injection molding tube container, the resin filling pressure (resin pressure in the cylinder) required to fill the mold in about 0.6 seconds was measured using a pressure sensor in the injection molding machine. The results are shown in Table 1.

<Transparency>
The central portion of the obtained injection-molded tube container was cut out to a size of 1 cm × 5 cm to prepare five samples. Using the cut-out sample, the haze was measured with a spectrophotometer (V-650 (manufactured by JASCO Corporation), and the average haze value was calculated. Based on the obtained average haze value, the following evaluation criteria were used. The transparency of the tube container was evaluated based on this. The results are shown in Table 1.
(Evaluation criteria)
S: Average haze value 0% or more and less than 15% A: Average haze value 15% or more and less than 30% B: Average haze value 30% or more and less than 45% C: Average haze value 45% or more and less than 60% D: Average haze value 60 %that's all

<Flexibility>
Using the obtained injection-molded tube container, a squeeze test was conducted by 10 subjects unrelated to the present invention.
Specifically, when the injection-molded tube container was crushed so as to extrude the contents, 10 subjects were asked to judge whether or not it was easy to crush the contents.
When the tube containers obtained in Examples 1 to 11 and Comparative Example 3 were used, all 10 subjects felt that it was easy to crush them (also evaluated as “OK”), and Comparative Examples 1 and 3 and When the tube container obtained in No. 2 was used, eight or more subjects felt that it was difficult to crush it (also evaluated as "impossible").

<Stress cracking resistance>
200 ml of a 1% benzalkonium chloride aqueous solution was placed in the tubes obtained in Examples and Comparative Examples, capped, and then stood in a constant temperature bath (40 ° C., 90% RH) with the cap up for 2 weeks. After that, it was taken out from the constant temperature bath and the crack of the tube was visually confirmed by hand. The test was performed using 10 tubes and evaluated based on the following evaluation criteria. The results are shown in Table 1.
(Evaluation criteria)
S: No cracks were found in any of the 10 tubes.
A: Cracks were confirmed in one or two tubes.
B: Cracks were confirmed in 3 to 5 tubes.
C: Cracks were confirmed in 6 to 9 tubes.
D: All 10 tubes broke.

1: Mouth 2: Body 3: Shoulder

Claims (4)

Biomass-derived low-density polyethylene (A) with a melt flow rate in the range of 20-50 g / 10 min measured under the conditions of 190 ° C. and 21.18 N load according to ASTM D1238.
Ethylene elastomer (B) with a density of 850-880 kg / m ³ or low density with a melt flow rate of 70-150 g / 10 min measured according to JIS K 6922-1 (190 ° C., 21.18 N). Contains polyethylene (C) and
The weight ratio of the biomass-derived resin represented by the following formula (1) is 60 to 100%.
Injection molded container.
Weight ratio of biomass-derived resin = Weight of biomass-derived resin used to manufacture the container x Biomass degree (%) of the resin / Total weight of resin used to manufacture the container ... (1) The container according to claim 1, wherein the container is an injection molded tube container. The container is a tube container including a head portion including a mouth portion and a shoulder portion and a body portion connected to the shoulder portion.
The container according to claim 1 or 2, which is an injection-molded tube container in which the head and the body are integrally molded. The container according to claim 3, wherein the body portion has a thickness of 0.5 to 0.8 mm.

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