JP2007070488A - Cap having biodegradability - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cap having an unsealing property equivalent to that of a pull open cap made of polyethylene which has conventionally be used or higher than that of the pull open cap and having excellent biodegradability under natural environment and under composting conditions, etc. and to improve scattering of a content fluid at the time of unsealing which became a problem in the conventional biodegradable cap made of resin. <P>SOLUTION: The cap is molded by using a composition obtained by formulating a biodegradable aliphatic polyester resin with a triethylene glycol monomethyl ether fatty acid ester used as a plasticizer in a specific ratio as a raw material. As a result, the pull open cap excellent in unsealing property is obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a synthetic resin cap having biodegradability, and more particularly to a pull-open cap having biodegradability.

Conventionally, caps are manufactured by known molding means such as injection molding and compression molding using synthetic resins such as polypropylene and polyethylene, but in recent years, caps are formed using biodegradable resins that decompose in natural environments. It has been proposed to do. (For example, refer to Patent Document 1) Capability required for the cap includes hermeticity, tamper evidence, unsealing property, etc. As a cap excellent in these performances, a pull having a breakable thin portion Open caps are widely used.

JP 2003-301096 A

The pull-open cap here refers to a cap having a cut-off area partitioned by a thin portion that can be broken on the top wall of the cap body, and having a finger hook in the cut-out area of the top wall. A cap having a column extending upward from a cut region of the top wall and a pull ring connected to the column is exemplified, and the cap is mainly formed using polyethylene resin. In this type of cap, it is a well-known and commonly used technique to set the thickness of the breakable thin portion near 0.25 mm, but the thickness of the breakable thin portion using a biodegradable aliphatic polyester resin is known. Is set near 0.25 mm, there is a problem that it is difficult to open. Further, if the pull ring is pulled strongly at the time of opening, there is a problem that the breakable thin portion is torn off vigorously, and the content liquid adhering to the cut area is scattered and adheres to the user's clothes and the like.

The present invention provides a cap having an openability equal to or higher than that of a conventionally used polyethylene pull-open cap and having excellent biodegradability under composting conditions in a natural environment. Another object of the present invention is to improve the scattering of the content liquid at the time of opening, which has been a problem with conventional biodegradable resin caps.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained a cap using a composition in which triethylene glycol monomethyl ether fatty acid ester as a plasticizer is blended in a specific ratio as a plasticizer with the biodegradable aliphatic polyester resin. It has been found that a pull-open cap having excellent openability can be obtained by molding, and has led to the present invention.

According to the present invention, the cap is made of a biodegradable aliphatic polyester resin, and the cap includes a top wall in which a cut region is defined by a breakable thin portion, and a finger hook portion provided in the cut region. The biodegradable aliphatic polyester resin contains triethylene glycol monomethyl ether fatty acid ester in a specific ratio. The blending amount of the triethylene glycol monomethyl ether fatty acid ester with respect to the biodegradable aliphatic polyester resin is 2 to 40 parts by weight per 100 parts by weight of the biodegradable aliphatic polyester. In the present invention, the blending amount is preferably in the range of 10 to 25 parts by weight per 100 parts by weight of the biodegradable aliphatic polyester, from the viewpoint of openability.
The biodegradable aliphatic polyester resin used for the cap of the present invention is characterized by being a polyalkylene alkanoate, a copolymer thereof, or a mixture thereof. The biodegradable aliphatic polyester resin used for the cap of the present invention is characterized by being polybutylene succinate or a copolymer thereof, or a mixture thereof. The copolymer of polybutylene succinate used in the cap of the present invention is polybutylene succinate adipate. The biodegradable aliphatic polyester resin used for the cap of the present invention is characterized in that it has a high molecular weight using a chain extender. The copolymer of the biodegradable aliphatic polyester resin used for the cap of the present invention is polybutylene adipate terephthalate. The biodegradable aliphatic polyester resin mixture used for the cap of the present invention is characterized by comprising at least two selected from polybutylene succinate, polybutylene succinate adipate, and polybutylene adipate terephthalate. . The biodegradable aliphatic polyester resin used in the cap of the present invention contains 0.01 to 5 parts by weight of fatty acid, or fatty acid amide, or a mixture of fatty acid and fatty acid amide per 100 parts by weight of the biodegradable aliphatic polyester. It is characterized by blending. The biodegradable aliphatic polyester resin used for the cap of the present invention is characterized by blending 1 to 10 parts by weight of an antiblocking agent per 100 parts by weight of the biodegradable aliphatic polyester. The biodegradable aliphatic polyester resin used in the cap of the present invention is characterized by blending 0.1 to 10 parts by weight of a hydrolysis inhibitor per 100 parts by weight of the biodegradable aliphatic polyester. The finger hook portion of the cap of the present invention is characterized by comprising a support column extending upward from the cutout region and a pull ring connected to the support column.

According to the present invention, by adding triethylene glycol monomethyl ether fatty acid ester to a biodegradable aliphatic polyester resin, it is possible to achieve good openability while maintaining sealability without impairing biodegradability. In addition, it is possible to prevent the content liquid from splashing when opened.

The present invention will be described in detail below.
In the present invention, the cap is made of a biodegradable aliphatic polyester resin, and the cap has a top wall in which a cut region is defined by a breakable thin portion, and a finger hook portion provided in the cut region. The biodegradable aliphatic polyester resin contains triethylene glycol monomethyl ether fatty acid ester, and the triethylene glycol monomethyl ether fatty acid ester is an ester of triethylene glycol monomethyl ether and fatty acid. The cap is characterized in that the fatty acid constituting the ester is enanthic acid, octylic acid, or isononanoic acid. When triethylene glycol monomethyl ether fatty acid ester is added to the biodegradable aliphatic polyester resin, the blending amount of triethylene glycol monomethyl ether fatty acid ester with respect to the biodegradable aliphatic polyester per 100 parts by weight of the biodegradable aliphatic polyester, By setting the amount to 2 to 40 parts by weight, excellent openability can be imparted to the cap. When the blending amount of the triethylene glycol monomethyl ether fatty acid ester with respect to the biodegradable aliphatic polyester is larger than the above range, the possibility that the liquid triethylene glycol monomethyl ether fatty acid ester bleeds out during use increases. Moreover, when the compounding quantity of the triethylene glycol monomethyl ether fatty acid ester with respect to biodegradable aliphatic polyester is smaller than the said range, the effect as a plasticizer of a triethylene glycol monomethyl ether fatty acid ester will fade, and it does not contribute to the improvement of openability. Preferably, the blending amount of the triethylene glycol monomethyl ether fatty acid ester with respect to the biodegradable aliphatic polyester is set to 10 to 25 parts by weight per 100 parts by weight of the biodegradable aliphatic polyester. Furthermore, the cap which improved the scattering of the content liquid at the time of opening can be obtained.

The biodegradable aliphatic polyester resin used in the composition of the present invention is obtained by condensing one or more of the following aliphatic polyhydric alcohols and aliphatic polybasic acids (or derivatives thereof). Can be used arbitrarily. In the present invention, the “biodegradable aliphatic polyester resin” includes those synthesized from cycloaliphatic compounds.

Examples of the aliphatic polyhydric alcohol that is one of the raw materials of the biodegradable aliphatic polyester resin used in the present invention include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,8- Examples include octylene glycol, 1,10-decamethylene glycol, and 1,4-cyclohexanedimethanol. Among these, ethylene glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol are preferable in view of physical properties of the resulting biodegradable aliphatic polyester resin.

Examples of the aliphatic polybasic acid (or a derivative thereof) that is one of the raw materials of the biodegradable aliphatic polyester resin used in the present invention include succinic acid, succinic anhydride, adipic acid, sebacic acid, and dodecanedicarboxylic acid. Examples include 1,4-cyclohexanedicarboxylic acid. Among these, succinic acid and adipic acid are preferable in view of physical properties of the resulting biodegradable aliphatic polyester resin. Moreover, you may use together aromatic polybasic acids, such as a terephthalic acid, as a copolymerization component.

Biodegradable aliphatic polyester resins suitable for the present invention include polybutylene succinate, which is a dehydration condensate of 1,4-butanediol and succinic acid, 1,4-butanediol and succinic acid, and adipic acid. Examples thereof include polybutylene succinate adipate which is a dehydration condensate. These biodegradable aliphatic polyester resins are preferably those having a high molecular weight using a chain extender such as lactic acid, polyvalent isocyanate, or acid anhydride. Moreover, a mixture of polybutylene adipate terephthalate obtained by dehydration condensation of 1,4-butanediol, adipic acid, and terephthalic acid, and the polybutylene succinate and polybutylene succinate adipate is exemplified. In addition, other biodegradable resins such as polylactic acid and starch can be used by mixing with the biodegradable aliphatic polyester resin exemplified above or a mixture thereof. As a method for mixing the mixture, known mixing means such as dry blending of pellets, melt kneading using an extruder or the like can be used.

As the fatty acid constituting the triethylene glycol monomethyl ether fatty acid ester exemplified as a preferred compound in the present invention, enanthic acid, octylic acid, isononanoic acid and the like are used. As a method for mixing the biodegradable aliphatic polyester resin or a mixture thereof and triethylene glycol monomethyl ether fatty acid ester, a known mixing means such as direct blending of resin pellets and a plasticizer, melt kneading using an extruder, or the like is used. Can do.

In the cap of the present invention, it is desirable to blend 0.01 to 5 parts by weight of a lubricant per 100 parts by weight of the biodegradable aliphatic polyester for the purpose of improving the releasability at the time of molding the resin. When molding by injection molding using a cold runner, it is necessary to consider not only the mold releasability of the mold part forming the molded product but also the mold releasability from the sprue. For this reason, in the cap of this invention, the mold release property at the time of shaping | molding can be improved and a moldability can be improved by mix | blending the said specific amount of lubricant.

Further, as an advantage of containing a lubricant, it is possible to improve the biting property of the resin into the screw during molding. When a specific amount of lubricant is included when the resin is introduced into the molding machine, the resin flows smoothly through the screw. However, if a lubricant exceeding the specified range is added, the bite property is adversely affected, resulting in molding failure.

As the lubricant, a so-called internal lubricant for imparting internal lubricity and an external lubricant for imparting external lubricity can be used together, and these can be used in combination. As the lubricant used in the present invention, all those generally used for resin molding can be applied. However, particularly when the resin composition of the present invention is used for food packaging, as a food additive. It is desirable to use one that has been approved for use.
Specifically, fatty acids such as stearic acid proposed in JP-A-8-27363, erucic acid amide, methylene bis-stearic amide, ethylene bis-stearic amide, ethylene bis-palmitic acid amide, ethylene bis-oleic acid Fatty acid amides such as amides, or a mixture of the above fatty acids and fatty acid amides can be used.

In addition to the above-mentioned lubricant, it is necessary to improve the moldability by forming irregularities on the surface of the molded product of the cap, increasing the surface roughness, and adjusting the resin biting property to improve the moldability. The antiblocking agent is preferably added in an amount of 1 to 10 parts by weight per 100 parts by weight of the biodegradable aliphatic polyester. A conventionally well-known antiblocking agent can be used as an antiblocking agent, A talc particle can be used suitably.

The above-mentioned lubricant and antiblocking agent may be added by preparing a masterbatch containing these at a relatively high concentration, and may be an internal addition in which this masterbatch is blended, or an external addition in which an antiblocking agent is directly added to the pellet particles. good.

Further, in the present invention, for the purpose of suppressing hydrolysis, it is preferable to add 0.1 to 10 parts by weight of a hydrolysis inhibitor per 100 parts by weight of the biodegradable aliphatic polyester. Since the cap is frequently used for packaging a food seasoning solution containing water, hydrolysis resistance is required. In the present invention, by adding the specific amount of hydrolysis inhibitor, hydrolysis resistance can be improved without impairing the biodegradability inherent in the biodegradable aliphatic polyester resin. The type of the hydrolysis inhibitor is not particularly limited as long as hydrolysis can be suppressed.

Examples of the hydrolysis inhibitor include carbodiimide compounds, surface-treated inorganic fillers, synergistic silicates, hydrophobic waxes, hydrophobic plasticizers, and olefinic resins proposed in Japanese Patent No. 3514736 and Japanese Patent Application Laid-Open No. 2003-165917. At least one of the groups is selected.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.

A cap as shown in FIG. 1 was molded with an injection molding machine. Thereafter, the pull-open strength was measured, and the presence or absence of liquid leakage due to the pinhole in the breakable thin portion was examined. Furthermore, the scattering of the content liquid at the time of opening was confirmed by actually pull-opening. In addition, the triethylene glycol monomethyl ether fatty acid ester used as the plasticizer in this example is “Lactosizer GP-4001” manufactured by Arakawa Chemical Industries, Ltd.

(cap)
As shown in FIGS. 1 and 2, the pull-open cap A is connected to the top wall 3 in which the cutout region 2 is partitioned by the breakable thin portion 1, the column 5 extending upward from the cutout region 2, and the column 5. The pull ring 4 is provided. The cap A has an engaging projection 8 on the inner surface of the outer cylinder wall 7 that engages with an annular protrusion provided on the outer periphery of the mouth tube portion of the container (not shown), and the mouth tube portion is sealed with a stopper. Installed. In addition, it replaces with the said pull ring 4, A well-known finger hook part can be employ | adopted, such as providing a press protrusion so that a cutting area can be fractured | ruptured by a press. Further, the entire cut region may be cut off, or may be cut off with a part of the unbroken portion remaining. Moreover, the pouring hole formed by breaking the breakable thin wall portion can adopt a known shape as appropriate. However, as shown in FIG. 2a can also be narrowed. The mounting of the cap on the container is not limited to the above-described means, and a known means such as mounting with a screw can be employed.

(Measurement of pull open strength)
Using a tensile tester, the pull open strength was measured by the following procedure. After fixing a measurement sample that has passed 24 hours or more after molding with a jig, pull the pull ring at a speed of 300 mm / min in a direction 90 degrees above the top wall surface, and the initial peak value in the fracture process of the thin-walled portion ( Maximum) was recorded. As for the unsealing properties, those having a pull-open strength of less than 60N are good, those having a pull-open strength of 60N or more and less than 80N are acceptable, and those having a pull-open strength of 80N or more are impossible.

(Confirmation of liquid splash)
The content liquid was confirmed to be scattered when opened. A cap was attached to the container containing the content liquid, and the container was shaken up and down 10 times, and then the pullable ring was pulled to tear the breakable thin-walled portion to remove the cut region. At this time, a liquid with no liquid splash or a liquid with almost no liquid splash was good, a liquid with a slight liquid splash was allowed, and a liquid with a liquid splash was not allowed.

(Leakage test)
Using a desiccator, the presence or absence of liquid leakage due to pinholes in the breakable thin wall portion was confirmed under reduced pressure.
The test procedure is as follows.
A glass container is filled with 50% aqueous ethanol solution in which a methylene blue solution is dissolved, and then a cap is attached to the container. The cap has an engagement projection on the inner surface of the outer cylinder wall that engages with an annular protrusion provided on the outer periphery of the mouth tube portion of the glass container, and the cap is liquid-tight on the container mouth tube portion by a stopper. Installed. A container equipped with a cap is laid down for 20 minutes in a desiccator set to an internal pressure of 200 hPa, and then the presence or absence of liquid leakage is confirmed. Caps that did not leak were good, and caps that leaked were not.

Example 1
Using a resin consisting of 100 parts by weight of polybutylene succinate adipate, 25 parts by weight of triethylene glycol monomethyl ether fatty acid ester and 0.5 parts by weight of erucic acid amide, a cap having a ruptureable thin part having a thickness of 0.25 mm is injection molded. did. A leak test was performed in the desiccator, but no liquid leak from the thin breakable part was observed. When the pull-open strength was measured, it was 20 N, and the openability was good. Regarding the splattering of the liquid at the time of opening, the liquid hardly splattered and was good.

(Example 2)
Using a resin consisting of 100 parts by weight of polybutylene succinate adipate, 18 parts by weight of triethylene glycol monomethyl ether fatty acid ester and 0.5 parts by weight of erucamide, a cap having a ruptureable thin part having a thickness of 0.25 mm is injection molded. did. A leak test was performed in the desiccator, but no liquid leak from the thin breakable part was observed. When the pull-open strength was measured, it was 25 N, and the openability was good. About the splash of the content liquid at the time of opening, the liquid hardly scattered and was good.

(Example 3)
Using a resin consisting of 100 parts by weight of polybutylene succinate adipate, 11 parts by weight of triethylene glycol monomethyl ether fatty acid ester and 0.5 parts by weight of erucamide, a cap having a ruptureable thin part having a thickness of 0.25 mm is injection molded. did. A leak test was performed in the desiccator, but no liquid leak from the thin breakable part was observed. When the pull-open strength was measured, it was 48 N, and the openability was good. About the splash of the content liquid at the time of opening, the liquid hardly scattered and was good.

Example 4
Using a resin composed of 100 parts by weight of polybutylene succinate adipate, 5 parts by weight of triethylene glycol monomethyl ether fatty acid ester and 0.5 parts by weight of erucamide, a cap having a ruptureable thin part having a thickness of 0.25 mm is injection molded. did. A leak test was performed in the desiccator, but no liquid leak from the thin breakable part was observed. When the pull-open strength was measured, it was 65 N, and the openability was acceptable. About the splash of the content liquid at the time of opening, the splash of the liquid was slight and was possible.

(Example 5)
Using a resin consisting of 100 parts by weight of polybutylene succinate adipate, 30 parts by weight of triethylene glycol monomethyl ether fatty acid ester and 0.5 parts by weight of erucamide, a cap having a breakable thin part thickness of 0.30 mm is injection molded. did. A leak test was performed in the desiccator, but no liquid leak from the thin breakable part was observed. When the pull open strength was measured, it was 24 N, and the unsealing property was good. About the splash of the content liquid at the time of opening, the liquid hardly scattered and was good.

(Comparative Example 1)
Using a resin consisting of 100 parts by weight of polybutylene succinate adipate and 0.5 parts by weight of erucamide that does not contain triethylene glycol monomethyl ether fatty acid ester, a cap having a ruptureable thin part of 0.25 mm in thickness is injection molded. did. A leak test was performed in the desiccator, but no liquid leak from the thin breakable part was observed. When the pull-open strength was measured, it was 90 N, and the openability was not possible. About the splash of the content liquid at the time of opening, there was a splash of the liquid, and it was impossible.

(Comparative Example 2)
Using a resin consisting of 100 parts by weight of polybutylene succinate adipate, 50 parts by weight of triethylene glycol monomethyl ether fatty acid ester and 0.5 parts by weight of erucic acid amide, a cap having a ruptureable thin part having a thickness of 0.25 mm is injection molded. However, since the bleed-out was remarkable and the molded product was unsuitable for use, the experiment was canceled.
The results are shown in Table 1.

＊ポリブチレンサクシネートアジペート１００重量部あたりの配合量(重量部)を示す。

* Indicates the blending amount (parts by weight) per 100 parts by weight of polybutylene succinate adipate.

As is apparent from the above results, the cap is made of a biodegradable aliphatic polyester resin, and the cap is provided on the top wall in which the cut region is defined by a breakable thin portion and the cut region. In the cap having a finger part, the blending amount of the triethylene glycol monomethyl ether fatty acid ester with respect to the biodegradable aliphatic polyester is 2 to 40 parts by weight, preferably biodegradable fat, per 100 parts by weight of the biodegradable aliphatic polyester. By using a resin composition that is 10 to 25 parts by weight per 100 parts by weight of the polyester, it is possible to achieve good opening while maintaining sealing performance, and to prevent the contents from being scattered at the time of opening. be able to.
By blending 0.01 to 5 parts by weight of a fatty acid, or a fatty acid amide, or a mixture of a fatty acid and a fatty acid amide as a lubricant per 100 parts by weight of the biodegradable aliphatic polyester, the releasability can be improved. . Moreover, a moldability can be improved more by using together 1-10 weight part antiblocking agent per 100 weight part of biodegradable aliphatic polyester. Moreover, hydrolysis resistance can be improved by mix | blending 0.1-10 weight part hydrolysis inhibitor with respect to 100 weight part of biodegradable aliphatic polyester.

It is a partial cross section side view of the pull open cap used for the Example of this invention. It is a bottom view of the cap shown in FIG. 1 of this invention. It is a reference view (bottom view) of a pull open cap having a cutout region having a shape suitable for the present invention.

Explanation of symbols

A Pull open cap 1, 1a Breakable thin part 2, 2a Cut-out area 3 Top wall 4 Finger hook (pull ring)
5 Strut 6, 6a Strut connection 7 Outer cylinder wall 8 Engagement protrusion

Claims (16)

A cap made of a biodegradable aliphatic polyester resin, the cap having a top wall in which a cut-out region is defined by a breakable thin-walled portion, and a finger hook provided in the cut-out region, The biodegradable aliphatic polyester resin is compounded with a compound represented by the following general formula (1).

(R ⁰ is an alkyl group having 4 to 12 carbon atoms, R ¹ , R ² , R ³ and R ⁴ are hydrogen atoms or methyl groups, R ⁵ is an alkyl group having 1 to 8 carbon atoms, and l and l ′ are 0 to 0. An integer of 6, m and m ′ are integers of 0 to 6, (where 1 ≦ l + m ≦ 6, 1 ≦ l ′ + m ′ ≦ 6), n and n ′ are integers of 0 to 5 (where 1 ≦ n + n Represents' ≦ 5).) The cap according to claim 1, wherein a compound obtained by reacting (a) a fatty acid having 5 to 13 carbon atoms and (b) a compound represented by the following general formula (2) is blended.

(Wherein R1, R2, R3 and R4 are hydrogen atoms or methyl groups, R5 is an alkyl group having 1 to 8 carbon atoms, l and l ′ are integers of 0 to 6, m and m ′ are integers of 0 to 6) (However, 1 ≦ l + m ≦ 6, 1 ≦ l ′ + m ′ ≦ 6), n and n ′ represent integers of 0 to 5 (where 1 ≦ n + n ′ ≦ 5). The cap according to claim 1, wherein the component (a) of the compound is enanthic acid, octylic acid, or isononanoic acid. The cap according to any one of claims 1 to 3, wherein the component (b) of the compound is triethylene glycol monomethyl ether. The blending amount of triethylene glycol monomethyl ether fatty acid ester into the biodegradable aliphatic polyester resin is 2 to 40 parts by weight per 100 parts by weight of the biodegradable aliphatic polyester. Cap. The blending amount of triethylene glycol monomethyl ether fatty acid ester into the biodegradable aliphatic polyester resin is 10 to 25 parts by weight per 100 parts by weight of the biodegradable aliphatic polyester. Cap. The cap according to any one of claims 1 to 6, wherein the biodegradable aliphatic polyester resin is a polyalkylene alkanoate, a copolymer thereof, or a mixture thereof. 8. The cap according to claim 7, wherein the biodegradable aliphatic polyester resin is polybutylene succinate, a copolymer thereof, or a mixture thereof. The cap according to claim 8, wherein the copolymer of polybutylene succinate is polybutylene succinate adipate. 10. The cap according to any one of claims 1 to 9, wherein the biodegradable aliphatic polyester resin or a copolymer thereof has a high molecular weight using a chain extender. The cap according to claim 7, wherein the copolymer of the polyalkylene alkanoate is polybutylene adipate terephthalate. 12. The biodegradable aliphatic polyester resin mixture comprises at least two selected from polybutylene succinate, polybutylene succinate adipate, and polybutylene adipate terephthalate. A cap according to any one of the above. The biodegradable aliphatic polyester resin is characterized in that 0.01 to 5 parts by weight of a fatty acid, a fatty acid amide, or a mixture of a fatty acid and a fatty acid amide is blended per 100 parts by weight of the biodegradable aliphatic polyester. The cap according to any one of claims 1 to 12. 14. The biodegradable aliphatic polyester resin contains 1 to 10 parts by weight of an antiblocking agent per 100 parts by weight of the biodegradable aliphatic polyester. Cap. 15. The biodegradable aliphatic polyester resin is blended with 0.1 to 10 parts by weight of a hydrolysis inhibitor per 100 parts by weight of the biodegradable aliphatic polyester. Cap as described in. The cap according to claim 1, wherein the finger hook portion includes a support column extending upward from the cut region and a pull ring connected to the support column.

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