JP2001097412A - Resin cap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin cap for securely closing a cap section of a polyester resin bottle and to be immediately crushed and reused while being installed on the cap section of the separated and recovered polyester resin bottle. SOLUTION: A resin cap is constituted of a cap man body composed of a polyester resin A and a cap packing composed of a polyester resin B, and the elasticity modulus of the polyester resin A is 7000-30000 kg/cm2, while the elasticity modulus of the polyester resin B is 1000-15000 kg/cm2, and the relation represented by the elasticity modulus of the polyester resin A > the elasticity modulus of the polyester resin B is satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

[0001]

[0001] The present invention relates to a resin cap. More specifically, the present invention relates to a resin cap for closing a plug portion of a bottle (bottle).

[0002]

2. Description of the Related Art Conventionally, bottle-shaped containers are excellent in strength, portability, workability at the time of carrying out, and the like, and are used in large quantities as storage containers for transporting liquid substances. Glass is often used as a material for bottle-shaped containers.
Synthetic resins have come to be used in place of excellent properties such as strength such as transparency and impact resistance, ease of coloring, moldability and hygiene. Synthetic resins for the production of bottle-shaped containers include polyolefin-based resins, polyvinyl chloride-based resins, polyester-based resins, and polycarbonate-based resins, and bottle-shaped containers are used for detergents, shampoos, cosmetics, and other fragrances. Containers for storing beverages such as cosmetics, water, milk, juices, teas, carbonated beverages, and the like.

[0003] Among various types of resin bottles, PET resin bottles are different from other resin bottles in terms of transparency, high strength, oxygen barrier property, fragrance retention, safety and hygiene, and moldability. In particular, the bottle size has been put to practical use from a medium capacity of about 300 ml to a large capacity of 2000 ml, and its usage is overwhelming compared to other resin bottles. Often.

[0004] In recent years, the amount of resin bottles including PET bottles has rapidly increased, and most of these resin bottles are discarded after use. Therefore, environmental pollution becomes a problem. From the viewpoint of resources, recycling of container and packaging materials is obligatory, and the recovery rate is gradually increasing. However, as described above, there are many types of resins for manufacturing resin bottles, and the biggest problem in reusing the collected resin bottles is that different resin bottles are mixed with each other. That is, in the collected resin bottle,
If different resin bottles having incompatibility are mixed, the recovered resin bottle cannot be reused for other purposes. The problem that different resin bottles are mixed with each other is that a so-called separation and collection method is adopted in which the type of resin is checked and separated by engraving a symbol indicating the type of resin on the resin bottle. , To some extent, was avoided.

[0005]

[Problems to be Solved by the Invention] Conventionally, as a cap for closing the plug portion of a resin bottle including a PET bottle, mainly, it has moderate rigidity, slipperiness, heat resistance and moldability. Good polypropylene resin (hereinafter "P
P ") or a metal cap. The PP cap has a resin odor peculiar to polyolefin, and there is a case where odor transfer to bottle filling is a problem. Further, since the gas barrier property is inferior to that of the polyester resin, there is a disadvantage that the thickness must be increased.

[0006] Further, what is collected with the cap of the bottle closed by the cap may not be removed as it is and may be mixed into the polyester resin of the bottle body component. Is poorly compatible with the polyester resin of the bottle material, which causes contamination and lowers the quality of the recycled polyester resin, making it impossible to reuse it, etc. There is a disadvantage that the operation is complicated.

Further, as another method for preventing the cap resin component from being mixed into the resin component of the bottle body, the cap for closing the plug portion of the polyester resin bottle is manually removed before the polyester resin bottle is crushed. Have been done, but they are inefficient. The recovered olefin resin cap accounts for about 6 to 12% by weight of the bottle weight and cannot be overlooked, but is currently discarded without being reused. On the other hand, an aluminum cap, polyethylene and paper lamination film may be used as a seal packing for this purpose. The bottle collection problem is the same as above.

The above problem is caused by the fact that the bottle body and the cap are made of different materials, and if the bottle body and the cap are made of the same kind of material, the above-mentioned problem may occur. It is believed that the problem can be solved. In order to solve this problem, a hermetically sealed container lid made of polyester has been proposed (for example, see Japanese Patent Publication No. 61-20572). However, since the polyester resin container lid proposed here is crosslinked, there is a drawback that it cannot be reused after being ground together with the container body made of the polyester resin.

Further, a non-crosslinked PET cap may be used as the cap for closing the plug portion of the PET bottle. However, PET has a low crystallization rate and is difficult to manufacture by injection molding. It has not been put to practical use.
That is, when the cap is manufactured by the injection molding method, a PET cap molded product can be obtained by setting the mold temperature to a low temperature of about 30 ° C.

However, since the cap molded product is not crystallized and is in an amorphous state and has poor heat resistance, a high-temperature filling method is used when filling the bottle with a liquid, or a heat treatment of the bottle filling (content). Not only does the sterilization process cause whitening of the caps and changes in dimensions, but also when closing the bottle cap with the cap, there is no surface slipperiness, so it is difficult to screw it in or open it. Can not be sealed. In addition, when the high-temperature filling method is used in the filling step, when the temperature of the filling decreases, the pressure of the bottle is reduced, the outside air may be sucked, the deterioration of the filling, and aerobic bacteria may propagate. There is. In addition, if the temperature of the filling rises in the distribution step or the like, the filling may leak from the plugging portion, and there are many problems in practical use, especially in the case of a liquid food.

Under these circumstances, the inventors have conducted intensive studies to provide a resin cap which has solved the above-mentioned problems at once, and have completed the present invention.
That is, the objects of the present invention are as follows. 1. Provided is a resin cap capable of reliably closing a plug portion of a PET bottle. 2. Provided is a resin cap which can be used for pulverization and reuse without having to remove the cap even if the cap remains attached to the separated and collected PET bottle.

[0012]

[Means for Solving the Problems] In order to solve the above problems,
The present invention provides a cap body made of polyester resin A,
In the resin cap composed of the polyester resin B cap packing, the elastic modulus of the polyester resin A is 7000 to 30,000 kg / cm ² , and the elastic modulus of the polyester resin B is 1,000 to 15,000 kg / cm.
^{(2) The} resin cap is characterized by satisfying the following relationship: elastic modulus of polyester resin A> elastic modulus of polyester resin B.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The polyester resin in the present invention refers to a resin obtained by subjecting a dicarboxylic acid component and a glycol component to a condensation reaction. As the dicarboxylic acid component constituting the polyester resin, terephthalic acid, isophthalic acid,
2,6-dinaphthalenedicarboxylic acid, 1,5-dinaphthalenedicarboxylic acid, bis (4,4′-carboxyphenyl) methane, anthracenedicarboxylic acid, and 4,
Aromatic dicarboxylic acids such as 4′-diphenyl ether carboxylic acid, 1,4-cyclohexanedicarboxylic acid,
Examples include alicyclic dicarboxylic acids such as 4,4'-dicyclohexyldicarboxylic acid, aliphatic carboxylic acids such as adipic acid, sebacic acid, azelaic acid and dimer acid, and ester derivatives thereof. In the dicarboxylic acid component, the ratio of the aromatic dicarboxylic acid is determined by mechanical properties,
From the viewpoint of gas barrier properties and heat resistance temperature, preferably 70
Mol% or more, preferably 90 mol% or more.

The glycol component constituting the polyester resin preferably contains tetramethylene glycol and / or polytetramethylene oxide glycol as a main component, and further contains an aliphatic or alicyclic diol having 2 to 20 carbon atoms. And bisphenol derivatives. Specifically, ethylene glycol, propylene glycol, trimethylene glycol, 1,5-pentadiol, 1,6-hexanediol, neopentyl glycol, decamethylene glycol, cyclohexanedimethanol, 4,4′-dicyclohexylhydroxypropane, Examples include ethylene oxide addition diols of bisphenol A, polyethylene oxide glycol, polypropylene oxide glycol, and mixtures thereof. Further, a small amount of triol such as glycerin and trimethylolpropane may be mixed.

The glycol component is preferably tetramethylene glycol, polytetramethylene oxide glycol or a mixture of both, and the ratio of the mixture to the total glycol component is preferably 70 to 100 mol%, more preferably 90 to 100 mol%. １００100 mol%.

The cap body according to the present invention is made of a polyester resin A. Polyester resin A
Is a resin obtained by subjecting the dicarboxylic acid component and the glycol component to a condensation reaction. Among them, a polytetramethylene terephthalate-based material having a tetramethylene terephthalate unit of 70 mol% or more, preferably 80 mol% or more in consideration of heat resistance, gas barrier properties, moldability, food hygiene, recyclability, etc. Resins (abbreviated as PBT-based resins). Specific examples include polytetramethylene terephthalate, a 5 mol% copolymerized PBT resin with isophthalic acid, and a molecular weight of 1
000 polytetramethylene oxide glycol (PT
MG) 1 mol% copolymerized PBT resin, polyethylene glycol 1 mol% copolymerized PBT resin having a molecular weight of 2,000, and the like. PBT-based resins have a glycol component of tetramethylene glycol (abbreviated as TMG) and PTM.
When G is used in combination, the flexibility of the resin can be freely adjusted, the crystallization speed is high, the moldability is good, and the heat resistance is excellent.

The polyester resin A has a flexural modulus of 7
It is in the range of 000-30000 kg / cm ² . If the flexural modulus is less than 7000 kg / cm ² , the rigidity is insufficient and the cap may be deformed when the cap is closed with the cap, or the contents may leak due to creep deformation during long-term storage. In the worst case, it will come off and the packing will leak. If the flexural modulus exceeds 30,000 kg / cm ² , a gap may be formed between the screw of the cap part and the screw part of the plug part of the bottle body, or the plug part of the bottle may be broken if it is tightened too strongly. is there. The flexural modulus of the polyester resin A is preferably 8,000 to 28,000.
kg / cm ² .

The cap packing of the resin cap according to the present invention is made of a polyester resin B. Like the polyester resin A, the polyester resin B is also a polymer obtained by performing a condensation reaction between the dicarboxylic acid component and the glycol component. Among them, as a preferable material, terephthalic acid is 70 mol% or more, preferably 80 mol% in the dicarboxylic acid component.
As described above, polytetramethylene terephthalate-based resins in which the total amount of tetramethylene glycol and polytetramethylene oxide glycol in the glycol component is 70 mol% or more, preferably 80 mol% or more. Specific examples include a PTMG 2.5 mol% copolymerized PBT resin having a molecular weight of about 1000, a PTMG 5 mol% copolymerized PBT resin having a molecular weight of about 1000, an isophthalic acid 5 mol% and a PTMG 5 mol% terpolymerized PBT resin having a molecular weight of about 1000. And a polyethylene glycol 5 mol% copolymerized PBT resin having a molecular weight of about 2,000.

The polyester resin B has a flexural modulus of 1
The range is from 000 to 15000 kg / cm ² . If the flexural modulus is less than 1000 kg / cm ^2, it is too soft and twists when sealing with a cap, making it impossible to reliably seal and cannot be used. When the flexural modulus exceeds 15000 kg / cm ² ,
It is not preferable because it does not function as a cap packing due to little deformation at the time of tightening. The flexural modulus of the polyester resin B is preferably 2000-13000 kg / cm.
²

The polyester resin A and the polyester resin B need to have a flexural modulus satisfying a relationship of flexural modulus of the polyester resin A> flexural modulus of the polyester resin B. When this relationship is satisfied, the resin cap made of the polyester resin A is harder than the cap packing made of the polyester resin B, and the resin cap is deformed when the cap portion of the bottle is closed with the cap. Instead, only the cap packing is deformed, so that the plug portion of the bottle can be reliably sealed. The relationship between the flexural modulus of the polyester resin A and the flexural modulus of the polyester resin B is preferably 2000 kg / cm ² or more, and more preferably 3000 kg / cm ² or more.

The polyester resin A and the polyester resin B may be added with a crystal nucleus material such as talc or kaolin if necessary for improving the molding processability, or polyethylene wax for improving the releasability. , A higher fatty acid ester, a higher fatty acid metal salt and the like can be added in small amounts. In order to improve the thermal stability during processing of both resins, a thermal stabilizer such as hindered phenol may be added.
In any case, since the resin cap is used for foods such as drinking water and seasonings, the type of these processing aids is selected from materials approved by the Food Sanitation Law.

In order to manufacture the resin cap according to the present invention, (1) First, the cap packing manufactured in another process is fixed to the cavity of the injection mold, and the resin is injected into the cavity of the mold cavity. (Integral molding method), and (2) a method of manufacturing the cap body by injection molding and inserting the cap packing into the cap body to form a resin cap. The former method (1) is more efficient.

The polyester resin constituting the cap portion and the packing portion for the cap is made of PET which serves as a bottle body.
(Melting point: 250 to 265 ° C.), it is necessary that it does not react to generate a gelled product or to cause uncontrollable transesterification.
It is necessary that the temperature is lower than the melting temperature of T. The polyester resin A and the polyester resin B for producing the resin cap according to the present invention are compatible with PET for the bottle main body, do not react even when melt-mixed, and have a melting temperature of PET. Below about 235 ° C. Therefore, what is separated and collected can be crushed together with the bottle main body and reused while being closed without removing the cap from the cap portion of the bottle main body.

[0024]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

In the examples described below, the materials used are shown in the following Table 1, and various physical properties were evaluated by the following methods.

[0026]

[Table 1]

(1) Measurement of elastic modulus: The flexural modulus of the polyester resin A and the polyester resin B was measured according to ASTM-D7.
The measurement was performed in an environment at a temperature of 23 ° C. and a relative humidity of 50% in accordance with No. 90. (2) Sealing degree test: The capacity of the resin cap manufactured as a trial was 1.
Affixed to the mouth of a 5 liter carbonated beverage bottle (hereinafter abbreviated as "carbonated bottle") or a 2 liter natural water bottle (hereinafter abbreviated as "water bottle") Is a gas leak from a bottle after three cycles of cooling and heating (cooling from room temperature to -10 ° C and then rising to a high temperature) from -10 ° C to 80 ° C for water bottles. A method of visually observing the presence or absence of air, the presence or absence of external air suction, and the like. (3) Recyclability evaluation: carbonated bottles used for sealing test,
The water bottle is washed well with water, and the resin cap is crushed with a crusher and dried at a temperature of 120 ° C. for 5 hours. A method of stretching and comparing the spinnability, and visually observing the presence or absence of foreign matter (foreign matter) in the strand.

[Example 1] (Manufacture of resin cap) First, polyester resin B
Using a polyester resin-2 as a raw material, a cap packing was molded using an injection molding machine (model: PS40) manufactured by Nissei Plastics Co., Ltd. at a cylinder temperature of 230 ° C. and a mold temperature of 40 ° C. Then, the cap packing was set in a mold cavity for cap molding at a mold temperature of 80 ° C. as shown in a schematic longitudinal sectional view in FIG.
As a result, a cap was molded using polyester resin-1 to obtain a cap molded product in which packing was closely adhered as shown in a schematic longitudinal sectional view in FIG.

(Evaluation of Performance of Resin Cap) The caps of the carbonated bottle and the water bottle were closed with the cap molded product obtained by the above method, and a sealing test was performed. Even after repeating three times, the filling did not leak out, and no trace of the outside air being sucked into the carbonated bottle or the water bottle was found. In addition, evaluation of recyclability showed that even when the discharged strand was manually stretched, no uneven drawing was observed, the spinning property was good, the strand was transparent and uniform, and no bumps were observed.

[Comparative Examples 1 and 2] Caps originally attached to caps of a carbonated bottle (Comparative Example 1) and a water bottle (Comparative Example 2) (cap body: polypropylene, sealing material: polyethylene) Was carried out in the same manner as in Example 1 using the same method as in Example 1. As a result, no leakage of the filler was found in any case, and traces of external air being sucked into the carbonated bottle and the water bottle were obtained. I couldn't. However, in the evaluation of recyclability, the resin of the bottle body and the resin of the cap originally attached are not compatible, the strands become cloudy, and when stretched out by hand, lumps are recognized, and there is a problem with recycling use. confirmed.

[Examples 2 to 4, Comparative Examples 3 to 5] (Production of Resin Cap) First, polyester resin B
As, using the polyester resin described in Table 2,
A cap packing was manufactured by the method described in Example 1. Then, these cap packings are set in a mold cavity for cap molding as shown as a schematic longitudinal section in FIG.
Example 1 was prepared using the polyester resin described in Table 1.
The cap was molded by the method described in (1) to obtain a cap molded product in which the packing was closely adhered as shown in FIG.

(Evaluation of Performance of Resin Cap) The caps of the carbonated bottle and the water bottle were closed with the cap molded product obtained by the above method, and the sealing test was conducted in the same manner as in Example 1. , And the recyclability were evaluated. Table 2 shows the evaluation results.

[0033]

[Table 2]

From Table 2, the following becomes clear. (1) In the resin cap satisfying the requirements of the present invention, no filling or gas leakage was observed in the sealing test, and no foreign matter was found in the strands even in the recyclability evaluation (see Examples 1 to 4). ). (2) On the other hand, if the mouthpiece of the carbonated bottle and water bottle is closed with the originally attached cap, no filling or gas leakage is observed in the sealing test, but in the recyclability evaluation. In the sample, foreign matter was found to be mixed in the strand (see Comparative Examples 1 and 2). (3) Further, when the elastic modulus of the polyester resin A and the elastic modulus of the polyester resin B do not satisfy the requirements of the present invention, even if the plug part is closed with a cap molded product in close contact with the packing, it is sealed. Insufficient gas leakage was observed during heating (see Comparative Examples 3 to 5).

[0035]

As described in detail above, the present invention has the following particularly advantageous effects, and its industrial value is extremely large. 1. In the resin cap according to the present invention, when the cap body is made of a polyester resin A having a large elastic modulus and the packing for the cap is made of a polyester resin B having a small elastic modulus, the cap portion of the bottle is removed. The plug can be reliably closed. 2. In the resin cap according to the present invention, since the cap body and the cap packing are made of a polyester resin, when the bottle (bottle) body is made of PET, the resin cap is removed from the separately collected bottle. It is not necessary and can be immediately used for crushing and reuse.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a mold cavity for forming a cap.

FIG. 2 is a schematic longitudinal sectional view of an example of a resin cap according to the present invention.

[Explanation of symbols]

 1: Male mold 2: Female mold 3: Cavity 4: Cap body 5: Packing for cap

Continuing from the front page (72) Inventor Katsuhiko Sugiura 5-6-1 Higashi-Hachiman, Hiratsuka-shi, Kanagawa F-term in the Technology Center of Mitsubishi Engineering-Plastics Corporation (Reference) 3E084 AA04 AA12 AA24 AB01 BA01 CA01 CC03 DA01 DB12 DC03 FA09 FB01 GA04 GB04 HA02 HB03 HC03 HD01

Claims (5)

[Claims] 1. A resin cap comprising a polyester resin A cap body and a polyester resin B cap packing, wherein the elastic modulus of the polyester resin A is 7000 to 30,000 kg / cm ² , The elastic modulus of resin B is 1000-15000kg
/ Cm ² and the elastic modulus of the polyester resin A>
A resin cap, which satisfies the following relationship: the elastic modulus of the polyester resin B. 2. The resin cap according to claim 1, wherein the polyester resin A is a polytetramethylene terephthalate resin having a tetramethylene terephthalate unit content of at least 70 mol%. 3. The polyester resin B is a polytetramethylene terephthalate in which terephthalic acid is 70 mol% or more in the dicarboxylic acid component and the total amount of tetramethylene glycol and polytetramethylene oxide glycol in the glycol component is 70 mol% or more. The resin cap according to claim 1, wherein the cap is resin. 4. The resin cap according to claim 1, wherein the cap body and the cap packing are produced by an integral molding method. 5. A polyester resin bottle with a resin cap, wherein the resin cap according to claim 1 is used as a stopper for a polyester resin bottle.