JP7442311B2 - Cap with slit valve - Google Patents

Description

The present invention relates to a cap with a slit valve.

BACKGROUND ART A cap with a slit valve is sometimes used for containers containing viscous foods or seasonings such as ketchup, honey, and mayonnaise. A cap with a slit valve usually has a configuration in which a cross-shaped, radial, etc. slit is formed in an elastically deformable film installed at the opening of the cap. A container fitted with a cap with a slit valve retains its contents under normal pressure, but when the container body is pressurized to increase the internal pressure, the slit valve's slit is pushed open by the pressure of the contents. Things are ejected. Then, when the pressurization of the container body is stopped, the slit of the slit valve is closed by elasticity, and the discharge of the contents is stopped.

Silicone resins have traditionally been widely used as materials for slit valves because they have appropriate elasticity and are difficult to react with the contents. On the other hand, caps are often made of polypropylene (PP). Silicone resin is difficult to fuse with PP, so in order to attach a silicone resin slit valve to a PP cap, it is necessary to fit multiple parts together, making the manufacturing process for caps with slit valves complicated. There is a certain inconvenience.

In this regard, Patent Document 1 describes that a cap with a slit valve consisting of two parts, a cap base and a slit valve, is manufactured by insert molding or two-color molding. Patent Document 2 states that from the viewpoint of food hygiene, a styrene-based or olefin-based thermoplastic elastomer is preferable as a constituent material of a slit valve that can be molded in two colors.

Japanese Patent Application Publication No. 2015-051789 Japanese Patent Application Publication No. 2018-177296

When a styrene-based or olefin-based thermoplastic elastomer is used as the constituent material of the slit valve, it has good adhesion with the cap material, but when it comes into contact with oil-based foods (e.g., mayonnaise, bread spread, etc.), the slit valve The valve may swell due to oil. When the slit valve swells with oil, problems arise, such as the expansion of the slit diameter, which impairs liquid drainage, the adhesive strength with the cap, and the deformation of the valve, which impairs the retention of contents.

The present invention has been made in view of the above circumstances. Therefore, an object of the present invention is to provide a cap with a slit valve that has excellent adhesion between the cap base and the slit valve and suppresses swelling due to oil even when it comes into contact with oily foods.

The present invention for solving the above problems is as follows.

<Aspect 1> A cap base,
A cap with a slit valve, the cap having a slit valve provided at the mouth opening of the cap base and having a slit that opens when the internal pressure of the container increases,
The cap base is made of a resin containing polypropylene as a main component, and
The slit valve is made of an ethylene-hexene copolymer with a density of 0.90 g/cm ³ or less and a tensile modulus of 100 MPa or less,
Cap with slit valve.
<Aspect 2> The cap with a slit valve according to aspect 1, wherein the ethylene-hexene copolymer constituting the slit valve has a tensile modulus of 60 MPa or less.
<<Aspect 3>> The cap with a slit valve according to Aspect 1 or 2, wherein the cap base includes a lid body connected via a hinge.
<Aspect 4> The cap with a slit valve according to any one of aspects 1 to 3, wherein the cap base and the slit valve are heat-sealed.
<Aspect 5> The cap with a slit valve according to any one of claims 1 to 3, wherein the cap base and the slit valve are integrally molded.
<<Aspect 6>> A method for manufacturing the cap with a slit valve according to Aspect 4, comprising:
Molding the cap base using a resin containing polypropylene as a main component;
Molding the slit valve using an ethylene-hexene copolymer having a density of 0.90 g/cm ³ or less and a tensile modulus of 100 MPa or less, and integrating the cap base and the slit valve by heat sealing. A method of manufacturing a cap with a slit valve, including:
<<Aspect 7>> A method for manufacturing the cap with a slit valve according to Aspect 5, comprising:
Molding the cap base using a resin whose main component is polypropylene, and by two-color molding, the opening of the mouth of the cap base has a density of 0.90 g/cm ³ or less and a tensile modulus of 100 MPa. A method for producing a cap with a slit valve, the method comprising molding the slit valve using the following ethylene-hexene copolymer.

According to the present invention, there is provided a cap with a slit valve that has excellent adhesion between the cap base and the slit valve and suppresses swelling due to oil even when it comes into contact with oily foods.

FIG. 1 is a schematic perspective view for explaining an example of an embodiment of a cap with a slit valve according to the present invention. FIG. 2 is a sectional view taken along the line AA in FIG. 1, and shows an example of the positional relationship between the cap base and the slit valve in the cap with a slit valve of the present invention. FIG. 3 is a schematic cross-sectional view showing another example of the positional relationship between the cap base and the slit valve in the cap with a slit valve of the present invention.

《Cap with slit valve》
The cap with a slit valve of the present invention is
a cap base;
A cap with a slit valve, the cap having a slit valve that is provided at the mouth opening of the cap base and that opens when the internal pressure of the container increases,
The cap base is made of a resin whose main component is polypropylene, and
The slit valve is made of an ethylene-hexene copolymer with a density of 0.90 g/cm ³ or less and a tensile modulus of 100 MPa or less,
It is a cap with a slit valve.

The cap base may include a lid connected via a hinge.

Hereinafter, the constituent materials of the cap base and the slit valve in the cap with a slit valve of the present invention will be explained in order, and then the structure of the cap with a slit valve will be explained.
<Materials of the cap base>
The cap base in the cap with a slit valve of the present invention is made of a resin whose main component is polypropylene. "Resin containing polypropylene as a main component" is a resin consisting only of polypropylene, or a resin containing polypropylene and other resins, and the polypropylene content in the resin is more than 50% by mass, This refers to cases where the content is 60% by mass or more, 70% by mass or more, 80% by mass or more, 85% by mass or more, 90% by mass or more, 95% by mass or more, 98% by mass or more, or 99% by mass or more.

The polypropylene constituting the cap base may be a propylene homopolymer or a copolymer of propylene and other monomers. As other monomers, olefins other than propylene can be preferably used. Specifically, α-olefins having 2 or 4 to 10 carbon atoms can be exemplified, and ethylene, 1-butene, 1-pentene, or 1-hexene are preferable.

When polypropylene is a copolymer of propylene and another monomer, the copolymerization form may be a block copolymer, a random copolymer, or a mixture thereof.

The crystal structure of polypropylene may be any of isotactic, syndiotactic, and atactic.

The polypropylene constituting the cap base is particularly preferably a random copolymer or a block copolymer of propylene and ethylene, and the polypropylene has an isotactic crystal structure.

When the cap base includes a lid, the lid and other parts of the cap base may be made of the same kind of material or may be made of different materials. However, it is preferable to construct these from the same kind of material from the viewpoint that the cap base with the lid body can be manufactured in one step.

<Materials of slit valve construction>
The slit valve in the cap with a slit valve of the present invention is made of an ethylene-hexene copolymer having a density of 0.90 g/cm ³ or less and a tensile modulus of 100 MPa or less.

Ethylene-hexene copolymers are copolymers of monomers containing ethylene and hexene (eg 1-hexene). The ethylene-hexene copolymer may be a binary copolymer obtained by copolymerizing ethylene and hexene, or a multicomponent copolymer obtained by copolymerizing a monomer mixture containing other monomers in addition to ethylene and hexene. It may also be a copolymer. As other monomers, olefins other than ethylene and hexene can be preferably used. Specifically, α-olefins having 3 to 5 or 7 to 10 carbon atoms can be exemplified, with propylene, 1-butene, 1-pentene, or 1-octene being preferred.

The form of the ethylene-hexene copolymer may be a block copolymer, a random copolymer, or a mixture thereof.

The ethylene-hexene copolymer has a density of 0.90 g/cm ³ or less and a tensile modulus of 100 MPa or less. This requirement indicates that a predetermined amount of hexene is copolymerized in the ethylene-hexene copolymer. That is, the ethylene-hexene copolymer specified in the present invention has a lower density and tensile modulus than polyethylene, which is a homopolymer of ethylene. This is thought to be because the ethylene chains in the ethylene-hexene copolymer were broken by hexene units, making it impossible to maintain polyethylene crystals with high density and high tensile modulus.

In such ethylene-hexene copolymers, it is thought that tertiary carbon derived from hexene units exists in the polymer chain in a certain proportion, and it is believed that tertiary carbon derived from hexene units exists in the polymer chain in a certain proportion, and it is also difficult to bond with polypropylene, which also has a large number of tertiary carbons in the polymer chain. It is thought that the performance has been improved.

Therefore, the slit valve of the present invention made of such an ethylene-hexene copolymer has excellent adhesion to the cap base made of a resin mainly composed of polypropylene, and can be integrally molded with the slit valve or It is presumed that heat seal adhesion is now possible.

Furthermore, the ethylene-hexene copolymer specified in the present invention has a low tensile modulus, and when used as a slit valve, has excellent content discharge and liquid drainage properties.

Furthermore, the ethylene-hexene copolymer specified in the present invention has a high affinity with oils (long-chain fatty acids containing linear long-chain alkenyl groups) contained in foods due to the presence of tertiary carbon in the polymer chain. has been reduced. Therefore, it is thought that swelling due to oil in the food is suppressed.

The density of the ethylene-hexene copolymer constituting the slit valve in the cap with a slit valve of the present invention is 0.90 g/cm ³ or less, 0.89 g/cm ³ or less, or 0.88 g/cm ³ or less. There may be. The density of the ethylene-hexene copolymer is a value measured in accordance with JIS K7112.

The tensile modulus of the ethylene-hexene copolymer constituting the slit valve in the cap with a slit valve of the present invention is 100 MPa or less, 90 MPa or less, 80 MPa or less, 70 MPa or less, 60 MPa or less, 50 MPa or less, 45 MPa or less, 40 MPa or less , 35 MPa or less, 30 MPa or less, 25 MPa or less, or 20 MPa or less. The tensile modulus of the ethylene-hexene copolymer may be 5 MPa or more, or 10 MPa or more from the viewpoint of ensuring the strength and hardness required as a slit valve material. The tensile modulus of the ethylene-hexene copolymer is the tensile modulus (Young's modulus) obtained by conducting a tensile test at a tensile speed of 300 mm/min in accordance with JIS K7161.

The water contact angle of the ethylene-hexene copolymer constituting the slit valve in the cap with a slit valve of the present invention may be 90° or more, 92° or more, 94° or more, 96° or more, or 98°C or more, It may be 110° or less, 108° or less, 106° or less, 104° or less, 102° or less, or 100° or less.

The oil contact angle of the ethylene-hexene copolymer constituting the slit valve in the cap with a slit valve of the present invention may be 15° or more, 18° or more, 20° or more, 22° or more, or 24°C or more, It may be 40° or less, 35° or less, 30° or less, 28° or less, or 26° or less.

In general, water contact angle and oil contact angle are considered to be indicators of the compatibility of a sample with water and oil. However, surprisingly, in the present invention, the relationship between the water contact angle and oil contact angle of the ethylene-hexene copolymer and the oil resistance performance of the slit valve is not very high. That is, the oil contact angle of the ethylene-hexene copolymer specified in the present invention may be, for example, 15° or more and 40° or less, a value that does not indicate very high oil repellency. By using the ethylene-hexene copolymer specified in the present invention, a slit valve with sufficiently high oil resistance can be obtained even if the oil contact angle is within this range.

The water contact angle and oil contact angle of the ethylene-hexene copolymer are determined by a liquid drop method in which 3 μL of a test liquid is dropped onto a copolymer sample formed into a sheet and the contact angle is measured. As the test liquid, pure water is used to measure the water contact angle, and salad oil is used to measure the oil contact angle.

《Configuration of cap with slit valve》
The cap with a slit valve of the present invention is
a cap base;
A cap with a slit valve, the cap having a slit valve that is provided at the mouth opening of the cap base and that opens when the internal pressure of the container increases,
The cap base and the slit valve are each made of the materials described above.

In the cap with a slit valve of the present invention, the cap base and the slit valve may be integrally molded or heat-sealed.

The cap with a slit valve of the present invention can take any shape as long as it satisfies the above requirements and can function as a cap with a slit valve. Hereinafter, the structure of the cap with a slit valve of the present invention will be explained by showing a non-limiting example.

FIG. 1 shows a schematic perspective view for explaining an example of the configuration of a cap with a slit valve according to the present invention.

The cap with a slit valve (100) in FIG. 1 includes a cap base (10) and a slit valve (50) provided at the opening (13) of the mouth (12) of the cap base (10).

The cap base (10) may have a cap base flat part (11) and a cap base suspension part (15) held by the cap base flat part (11).

The cap base (10) has a mouth (12) with an opening (13) for protruding the contents. When the cap base (10) has a cap base flat part (11), the mouth part (12) may be formed to protrude from the center of the cap base flat part (11).

The cap with a slit valve (100) is used by being connected to a container opening (not shown) on the back side of the cap base (10) (an area not shown surrounded by the cap base suspension part (15)). It is planned that The connection between the back side of the cap base (10) and the container opening may be arbitrary, and may be, for example, a screw-in type, a snap-fit type, a beyonet type, or the like.

The cap base (10) of the cap with slit valve (100) of FIG. 1 has a lid (30) connected via a hinge (20). The lid (30) can be opened and closed by swinging by the hinge (20). In FIG. 1, the cap (100) with a slit valve is shown with the lid (30) in an open state.

The lid body (30) may have a lid suspension part (31) rising from the hinge (20), and a lid flat part (32) held by the lid suspension part (31). The lid (30) forms a seal together with the mouth (12) when in the closed state. For example, the lid (30) may further include a lid sealing formation (35) for contacting the mouth (12) to form a seal when in the closed state. This lid sealing formation (35) may have, for example, rings, fins, pins, inserts, sleeves, skirts, etc. to form the seal.

In the cap (100) with a slit valve shown in FIG. 1, a slit valve (50) is provided in the opening (13) of the mouth (12) of the cap base (10). This slit valve (50) is provided with a slit, and the slit is closed under normal pressure and the contents are retained, but if the container body (not shown) is pressurized to increase the internal pressure of the container. The slit of the slit valve (50) is pushed open by the pressure of the contents, and the contents are discharged. Further, when the pressure on the container body (not shown) is stopped, the slit is closed by its elasticity and the discharge of the contents is stopped.

In the cap (100) with a slit valve shown in FIG. 1, the slit of the slit valve (50) is cross-shaped, but the shape of the slit may be arbitrary as long as the contents can be discharged, and may be radial, etc. Good too.

FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1, and shows an example of the positional relationship between the cap base (10) and the slit valve (50) in the cap (100) with a slit valve. In the cap with a slit valve (100), the slit valve (50) engages with a recess formed inside the mouth (12) of the cap base (10) and is arranged over the entire area of the opening (13). ing.

The positional relationship between the cap base (10) and the slit valve (50) in the cap with a slit valve (100) is not limited to the embodiment shown in FIG. 2, and may be in any other embodiment. . For example, in the cap (200) with a slit valve shown in FIG. 3, the cap (200) with a slit valve is disposed on the upper end of the mouth (12) of the cap base (10) so as to completely cover the mouth (12).

In the cap with a slit valve of the present invention,
The cap base (10) is made of a resin whose main component is polypropylene; and the slit valve (50) is made of an ethylene-hexene copolymer with a density of 0.90 g/cm ³ or less and a tensile modulus of 100 MPa or less. The requirement is that it consists of;
The cap base and the slit valve may be integrally molded or heat sealed.

The shape of the cap with a slit valve shown in FIG. 1 is only one example of the embodiment of the present invention, and the shape of the cap with a slit valve of the present invention is not limited to the shape shown in FIG. 1. The cap with a slit valve of the present invention can take any shape as long as it can function as a cap with a slit valve.

《Method for manufacturing cap with slit valve》
The cap with a slit valve of the present invention may be manufactured by any method as long as it has the above configuration. For example, it may be manufactured by any of the following methods.

Molding a cap base using a resin whose main component is polypropylene (cap base molding process);
Molding a slit valve using an ethylene-hexene copolymer with a density of 0.90 g/ ^cm3 or less and a tensile modulus of 100 MPa or less (slit valve molding process), and integrating the cap base and the slit valve by heat sealing. (heat sealing process)
A method for manufacturing a cap with a slit valve (first manufacturing method); or molding a cap base using a resin containing polypropylene as a main component (cap base molding step); and molding a cap base by two-color molding. Molding a slit valve using an ethylene-hexene copolymer with a density of 0.90 g/cm ³ or less and a tensile modulus of 100 MPa or less at the opening of the mouth (integral molding process).
A method for manufacturing a cap with a slit valve (second manufacturing method).

<First manufacturing method>
The first manufacturing method for manufacturing the cap with a slit valve of the present invention includes a cap base molding process, a slit valve molding process, and a heat sealing process. According to this first manufacturing method, the positional relationship between the cap base and the slit valve is as shown in FIG. It is suitable for manufacturing.

(Cap base forming process)
In the cap base molding step, the cap base is molded using a resin whose main component is polypropylene. The resin containing polypropylene as a main component may be appropriately selected depending on the desired composition of the cap. The cap base may be molded by a known method, for example, by an appropriate molding method such as injection molding, compression molding, vacuum molding, pressure molding, or the like.

(Slit valve molding process)
In the slit valve molding step, a slit valve is molded using a predetermined ethylene-hexene copolymer. The ethylene-hexene copolymer may be appropriately selected depending on the desired characteristics of the slit valve. The slit valve may be molded by a known method, for example, injection molding, compression molding, vacuum molding, air pressure molding, or any other appropriate molding method.

(Heat sealing process)
In the heat sealing step, the cap base obtained in the cap base forming step and the slit valve obtained in the slit valve forming step are integrated by heat sealing to obtain a cap with a slit valve. In this case, for example, after the slit valve is placed on the upper end of the mouth of the cap base, heat sealing may be performed by a known method, for example.

(Time of slit valve slit formation)
The slit of the slit valve may be formed at the same time as the slit valve is molded, after molding and before the heat sealing process, or after the heat sealing process. In the slit valve molding process, ethylene-hexene copolymer is molded into a sheet larger than the desired size of the slit valve, this is placed on the upper end of the opening of the cap base, and the sheet is heat-sealed. A preferred embodiment of the present invention includes cutting to size and simultaneously forming slits.

<Second manufacturing method>
The second manufacturing method for manufacturing the cap with a slit valve of the present invention includes a cap base molding step and an integral molding step. According to this second manufacturing method, the positional relationship between the cap base and the slit valve is such that the slit valve engages with the recess formed inside the mouth of the cap base, as shown in FIG. A cap with a slit valve, such as the one shown in FIG. 3, is suitable for manufacturing a cap with a slit valve, etc., in which the slit valve is disposed on the upper end of the mouth of the cap base.

(Cap base forming process)
In the cap base molding step, the cap base is molded using a resin whose main component is polypropylene. The resin containing polypropylene as a main component may be appropriately selected depending on the desired composition of the cap. The cap base molding step in the second manufacturing method may be performed in the same manner as the cap base molding method in the first manufacturing method.

(Integrated molding process)
Next, in the integral molding step, a slit valve is molded into the mouth opening of the cap base using a predetermined ethylene-hexene copolymer by two-color molding. As a result, a cap with a slit valve in which the cap base and the slit valve are integrated is obtained.

The two-color molding applied here is a technology that integrates multiple materials of different types, for example, by adding parts made of different materials to a base molded part and integrating them. good. In the present invention, for example, the cap base obtained in the cap base molding step is placed at a predetermined position in a mold, and a predetermined ethylene-hexene copolymer is placed in the mouth opening of the cap base in the mold. A method of forming a slit valve formed by combining may be used. The ethylene-hexene copolymer may be appropriately selected depending on the desired characteristics of the slit valve. Since the ethylene-hexene copolymer specified in the present invention has excellent adhesion to resins whose main component is polypropylene, this two-color molding provides a cap with a slit valve that has excellent adhesion between the cap base and the slit valve. be able to.

Two-color molding is also called insert molding, overmolding, double molding, etc. in the industry.

(Time of slit valve slit formation)
The slits of the slit valve may be formed during the integral molding process or may be formed after the integral molding. It is also a preferred embodiment of the present invention to form slits after the predetermined ethylene-hexene copolymer is integrally molded so that it is disposed as a sheet without slits at or near the upper end of the cap base opening. included.

《Example 1》
In Example 1, an ethylene-hexene copolymer produced by a metallocene high-pressure method manufactured by Japan Polyethylene Co., Ltd. under the trade name "Kernel KS560T" was used as the resin for the slit valve, and its various physical properties were evaluated.

(1) Evaluation of density The density of the resin for slit valves was measured in accordance with JIS K7112.

(2) Evaluation of contact angle 1.0 g of resin for slit valve was sandwiched between two sheets of peelable PET, and using a 0.1 mm SUS spacer, heat press was performed using a heat press testing machine manufactured by Imoto Seisakusho Co., Ltd. A sheet sample with a thickness of 0.1 mm was prepared. Using an automatic contact angle meter manufactured by Kyowa Interface Science Co., Ltd., product name "DM501Hi", 3 μL of the test liquid was dropped onto the obtained sheet sample to measure the contact angle. As the test liquid, pure water was used to measure the water contact angle, and salad oil manufactured by Nisshin Oilli Group Co., Ltd. was used to measure the oil contact angle.

(3) Evaluation of tensile modulus A sheet sample with a thickness of 0.1 mm was prepared by sandwiching 1.0 g of resin for a slit valve between two sheets of peeled PET and hot pressing using a 0.1 mm spacer made of SUS. This sheet sample was cut into test pieces with a width of 15 mm, and a tensile test was performed at a tensile speed of 300 mm/min in accordance with JIS K7161 to determine the tensile modulus (Young's modulus).

If the tensile modulus is 100 MPa or less, it can be evaluated that the usability as a slit valve is good, and if it is 60 MPa or less, it can be evaluated that the usability as a slit valve is excellent. The feeling of use as a slit valve refers to the ease with which the contents can be extruded and the ease with which liquid can be drained when extrusion of the contents is stopped.

(4) Evaluation of oil resistance 1 g of resin for a slit valve was sandwiched between two sheets of peelable PET, and a sheet sample with a thickness of 0.6 mm was produced by hot pressing using a 0.6 mm spacer made of SUS. This sheet sample was immersed in "Kewpie Mayonnaise" manufactured by Kewpie Corporation and allowed to stand at 40° C. for 7 days (168 hours). The mass of the sample before and after immersion was measured using an electronic balance, and the increase in mass was used as an index of oil resistance. If this mass increase is less than 1.0% by mass, preferably 0.9% by mass or less, it can be evaluated that the oil resistance is excellent.

(5) Evaluation of adhesion to cap base Random polypropylene (r-PP) was used as the material for the cap base, and the adhesion between the slit valve resin and the cap base was evaluated. A random PP sheet and a slit valve resin sheet each having a thickness of 0.3 mm were produced by sandwiching 3 g each of random polypropylene and slit valve resin between two sheets of peelable PET and heat pressing using a 0.3 mm SUS spacer. did.

Each of these sheets was cut into a rectangle of 50 mm x 100 mm, the two sheets were stacked on top of each other, and thermocompression bonding was performed for 30 seconds at 180° C. and 5 MPa to obtain a peel test sample. At this time, a grip portion for the tensile test was created by sandwiching the peeled PET over a length of 4 cm from the short side end of the stacked sheets in the long side direction.

The obtained peel test sample was subjected to a 180° peel test at a tensile rate of 300 mm/min in accordance with JIS Z0237 to examine its peel strength, and evaluated according to the following criteria.
When the peel strength was 10 N/25 mm or more: Adhesion "Good"
When the peel strength was less than 10N/25mm: Adhesion "Poor"

The results of all the above measurements are shown in Table 1.

《Example 2 and Comparative Examples 1 to 7》
Various evaluations were performed in the same manner as in Example 1, except that the resin for the slit valve was changed as shown in Table 1. The results are shown in Table 1.

In Table 1, the abbreviations of the names of the resins for slit valves have the following meanings.
KS560T: Manufactured by Japan Polyethylene Co., Ltd., ethylene-hexene copolymer produced by metallocene high pressure method, product name: "Kernel KS560T"
KS-340T: Manufactured by Japan Polyethylene Co., Ltd., ethylene-hexene copolymer produced by metallocene high pressure method, product name: "Kernel KS340T"
RBB6650-50: Manufactured by Dow Toray Industries, Inc., silicone resin, product name "Xiameter RBB6650-50"
AR-850C: Manufactured by Aron Kasei Co., Ltd., styrene elastomer, product name "AR-850C"
L1850K: Manufactured by Asahi Kasei Corporation, low density polyethylene, product name "Suntech L1850K"
TPX MX002: manufactured by Mitsui Chemicals, Inc., polymethylpentene, product name "TPX MX002"
SP2520: Made by Prime Polymer Co., Ltd., ethylene-hexene copolymer produced by metallocene method, product name "Evolu SP2520"
10100J: Made by Prime Polymer Co., Ltd., ethylene-butene copolymer, product name "Neozex 10100J"
r-PP: random polypropylene

According to Table 1, the silicone resin commonly used as a slit valve material had poor adhesion to the cap base material (Comparative Example 1). Furthermore, the styrene elastomer had a low tensile modulus and was excellent in the usability of the slit valve, but its oil resistance was poor (Comparative Example 2). Furthermore, although general polyolefins had excellent oil resistance, they had extremely high tensile modulus, resulting in poor usability for slit valves and poor adhesion to cap base materials (Comparative Examples 3 and 4). ).

Furthermore, even when the ethylene-hexene copolymer was used, if the density was higher than the range specified in the present invention, the tensile modulus was high and the adhesion to the cap base material was poor (Comparative Example 5). . The ethylene-butene copolymer also had a high tensile modulus and poor adhesion to the cap base material (Comparative Example 6).

Furthermore, although polypropylene had excellent adhesion to the cap base material, it had a significantly high tensile modulus and was considered to have poor usability as a slit valve material (Comparative Example 7).

In contrast, it is clear that in Examples 1 and 2, in which the ethylene-hexene copolymer satisfying the predetermined requirements of the present invention was used, the slit valve had excellent usability as well as excellent adhesion to the cap base material. It has been verified that these materials are suitable as slit valve materials.

10 Cap base body 11 Cap base plane part 12 Mouth part 13 Opening part 15 Cap base suspension part 20 Hinge 30 Lid body 31 Lid suspension part 32 Lid plane part 35 Lid sealing formation part 50 Slit valve 100, 200 Cap with slit valve

Claims (9)

a cap base;
A cap with a slit valve, the cap having a slit valve provided at the mouth opening of the cap base and having a slit that opens when the internal pressure of the container increases,
The cap base and the slit valve are bonded to each other at an outer peripheral end of the slit valve,
the slit is formed in the center of the slit valve;
The cap base is made of a resin containing polypropylene as a main component, and
The slit valve is made of an ethylene-hexene copolymer having a density of 0.89 g/cm ³ or less and a tensile modulus of 40 MPa or less,
Cap with slit valve. The cap with a slit valve according to claim 1, wherein the central portion of the slit valve is substantially flat. The cap with a slit valve according to claim 1 or 2, wherein the ethylene-hexene copolymer constituting the slit valve has a mass increase rate before and after the immersion test of less than 1.0% by mass. The cap with a slit valve according to any one of claims 1 to 3 , wherein the cap base includes a lid body connected via a hinge. The cap with a slit valve according to any one of claims 1 to 4 , wherein the cap base and the slit valve are heat-sealed. The cap with a slit valve according to any one of claims 1 to 4 , wherein the cap base and the slit valve are integrally molded. A method for manufacturing a cap with a slit valve according to claim 5 , comprising:
Molding the cap base using a resin containing polypropylene as a main component;
Molding the slit valve using an ethylene-hexene copolymer having a density of 0.90 g/cm ³ or less and a tensile modulus of 100 MPa or less, and integrating the cap base and the slit valve by heat sealing. A method of manufacturing a cap with a slit valve, including: A method for manufacturing a cap with a slit valve according to claim 6 ,
Molding the cap base using a resin whose main component is polypropylene, and by two-color molding, the opening of the mouth of the cap base has a density of 0.90 g/cm ³ or less and a tensile modulus of 100 MPa. A method for manufacturing a cap with a slit valve, the method comprising molding the slit valve using the following ethylene-hexene copolymer. The method for manufacturing a cap with a slit valve according to claim 7 or 8 , wherein the central portion of the slit valve is substantially flat.

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