JPS5837181B2 - Bottle lid with gasket and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION CI) BACKGROUND OF THE INVENTION Technical Field The present invention relates to a bottle cap having a gasket consisting of cork grains bonded with thermoplastic resin.

The present invention involves installing a gasket on the inner surface of a bottle lid in-situ.
si'tu).

More specifically, the present invention relates to a method of forming a gasket on the inner surface of a bottle lid from a mixture of cork particles and thermoplastic resin.

PRIOR ART Bottle caps made primarily of metal with a gasket on the contact surface with the bottle mouth are, for example, well known as crowns;
Cork has conventionally been used as a gasket material in this case.

The cork gaskets currently in use are made by gluing cork grains together to form a disk.

That is, cork grains (with a maximum dimension of about 0.5 to 5) are mixed with a suitable adhesive (must be a hydrophilic polymer adhesive with strong polarity such as albumin, casein, or egg white). (Cork grains 80-90, adhesive 10-2
0 da), heat and compress it to form it into a round bar or plate shape (the diameter is slightly larger than that of a cork disc used as a gasket), age it (about 2 weeks), and then shape it to a specified diameter. Cut into thick discs.

The cork disc manufactured in this manner is an excellent gasket due to the good elasticity inherent to cork.

However, cork's elasticity is due to its cushioning properties due to the large amount of air it contains, and its rebound elasticity (
This is because the gasket is compressed at the mouth of the bottle during long-term use, and the stored air leaks out, and the cell walls adjust to the compressed shape and generate repulsive force. It has the disadvantage of being lost.

Irreversible deformation caused by long-term pressurization is generally a problem for gaskets, but it is a particularly serious problem from the point of view of maintaining gas pressure when the contents of the bottle contain high gas pressure, such as beer and carbonated drinks. becomes.

1. Since this gasket is made in advance as a cork disk, it is necessary to insert and glue it inside the lid after that. In addition to having to be crimped, it is not always easy to insert the disk concentrically into the inside of the lid.

Non-concentric insertion of the disc into the inside of the lid and another problem, deflection of the disc (which can occur when cutting the cork rod when using the manufacturing method described above), can lead to failure as a gasketed bottle lid. Preventing the occurrence of non-defective products and detecting the occurrence of non-defective products must be done manually, which poses a problem in the case of mass-produced products such as bottle caps.

In addition, corkscrews generate cork dust, the reaction between tannins and iron causes tannin iron to grow and turn black, and it is relatively more expensive than those manufactured in the above-mentioned manner. There are other problems.

Another example of gaskets for bottle lids is one that uses a method that involves placing a thermoplastic resin, such as low-density polyethylene, in a molten state inside the lid and pressing it against the inside of the lid to form a gasket inside the lid. There is.

According to this method, the gasket shape or material is handled in a fluid state and the gasket is placed "in situ" within the lid.
Equipment for inspection of J-type products (Insvector)
This solves the above-mentioned problems that were encountered when the cork disc was manufactured in advance and inserted into the lid and glued. Although one layer is usually provided on the inner surface of the lid, this layer can also be provided in the form of a metal plate (blank) for manufacturing the lid.

This method is also satisfactory in terms of odor, hygiene, cost, and consistency.

For this reason, this method is still in practical use today, and it is expected that it will be even more widely adopted in the future due to its characteristics suitable for mass production and the potential of cork as a natural resource. Several gasket forming apparatuses (lining machines) have already been proposed whose main elements are a thermoplastic resin extrusion apparatus and a pressing apparatus.

However, this method also has problems.

In other words, commonly used thermoplastic resins, such as low-density polyethylene, are hard as bottle lid gasket materials, so the mouths of glass bottles are easily damaged during capping, and the sealing performance is poor for bottles with poor shape. If the lid is subjected to an impact after capping (for example, if the bottle is dropped), the bottle mouth is likely to be damaged and/or leakage may occur.

[Summary of the old invention] The present invention aims to solve the above-mentioned problems, and provides a gasketed bottle in which a gasket made of a mixture of cork grains and thermoplastic resin is provided inside the bottle lid under limited conditions. Provide a lid, and place this broken gasket on the inside of the bottle lid (i
n situ ) formation.

Therefore, the bottle lid with a gasket according to the present invention consists of a bottle lid and a gasket formed inside the lid, and this gasket connects the cork grains with a maximum dimension of 5 or less, and the cork grains on the surface of the gasket. It is characterized by being formed from a thermoplastic resin that substantially covers the surface (and the cork grain content in this gasket forming material is 5 to 50% by weight). be.

1. The method for producing a gasketed bottle lid according to the present invention includes placing a predetermined amount of a gasket-forming composition made of a mixture of cork grains and a thermoplastic resin inside a bottle lid in a molten state, and applying this composition in a molten state. This composition is characterized in that the composition is pressed against the inner surface of the bottle cap to form a gasket on the inside of the bottle cap, and this gasket-shaped composition is defined as follows.

(1) The cork grains must have a maximum dimension of 5 mmJJ or less.

(2) The cork grain content in the gasket forming composition is 5
~50 weight.

(3) The surface of the cork grains on the gasket surface to be shaped should be substantially covered with the thermoplastic resin.

Effect: Using such a specific cork particle/thermoplastic resin mixture as a gasket forming material, a gasket is formed in-situ on the inner surface of the lid from its melt, so that the cork particles are substantially coated with the thermoplastic resin on the gasket surface. When a gasket is provided, the various problems found in the above-mentioned cork gaskets and thermoplastic resin in-situ gaskets are solved.

Although the gasket obtained by the present invention has elasticity that is understood to be due to cork, it has less irreversible deformation due to long-term pressurization, which is observed in cork gaskets (
(See Reference Example 2 below).

The fact that there is little irreversible deformation due to long-term pressurization is mainly due to the fact that the cork grains are embedded in the thermoplastic resin matrix and that the surface of the gasket surface is substantially covered with the thermoplastic resin. The gasket of the present invention, which is made of a thermoplastic resin disc with cork grains embedded therein, is understood to be due to this, but the gasket of the present invention, which is made of a thermoplastic resin disc with cork grains embedded therein, avoids the problems inherent in both gasket materials (too hard and irreversible deformation). It can be said that it was unexpected that there was one.

Cork granules in the present invention should not be considered simply as a filler for thermoplastic resins.

This is because cork grains have a low specific gravity, so the volume of the cork grains used in the present invention is considerably larger than the volume of the thermoplastic resin, and therefore, the produced gasket has cork grains dispersed in the thermoplastic resin matrix. Rather, it should be said that the cork grains are bound together using a thermoplastic resin as a binder.

Although the thermoplastic resin in the present invention functions as a binder, unlike the so-called hydrophilic polymer adhesive used in conventional cork disc manufacturing, the thermoplastic resin is not an adhesive for cork grains.

Typical thermoplastic resins used in the present invention are low density polyethylene and ethylene-vinyl acetate copolymers, but these both have little ability to bond cork granules to each other, and therefore are not suitable for use in the gasket form or in the present invention. If the composition contains cork grains of more than 50 weight width, the cork grains will not adhere to each other and will fall apart.

Disadvantages of forming a gasket in-situ from a thermoplastic resin melt include the high viscosity of the melt and the stringiness that occurs when cutting or weighing the melt into small pieces of a predetermined amount. (Unexamined Japanese Patent Publication No. 51-985
Publication No. 86).

However, the aggregate made of molten thermoplastic resin mixed with cork particles according to the present invention should rather be an aggregate made of a large amount of cork particles connected by molten thermoplastic resin,
Marks shear force during kneading and cutting. 7yo L, the problems of high viscosity and stringiness are almost never observed.

CI) Specific description of the invention 1. Cork grain The cork grain targeted by the present invention has a maximum particle size of 5i.
Emi or less than 5 ■.

The individual particles of cork grains are usually flake-like rather than spherical, so the maximum dimension of such particles is the diameter for spherical particles, but for flake particles it is the plate-like shape. This is the maximum dimension of the surface.

If the maximum size of the cork particles exceeds 5 mm, it becomes difficult to uniformly disperse the cork particles in the thermoplastic resin matrix, and it also becomes difficult to coat the cork particles on the surface of the produced gasket with the thermoplastic resin.

The lower limit of the maximum size of the cork particles is arbitrary as long as the resulting gasket has a desired elasticity.

Generally speaking, as the cork particles become finer, the amount of thermoplastic resin used to bind the particles increases, and therefore the resulting gasket becomes harder with less elasticity.

A preferable lower limit of the maximum dimension is about 0.5n.

The cork grains used in the present invention do not necessarily have to have a uniform particle size.

Furthermore, the cork grains used in the present invention may be the same as those used for conventional cork disc production.

In the present invention, cork grains can be used at -1x, but they can also be used after being subjected to appropriate pretreatment if necessary.

Waxing is one such pretreatment.

If the cork grains are treated (coated on the surface of the cork grains) with a small amount of wax, for example 10 parts by weight, the cork grains can be easily uniformly dispersed in the thermoplastic resin.

As waxes in this case, in addition to the typical fatty acids and higher monohydric mono- or dihydric alcohol tonoesters, montan wax, petroleum wax and others can be used.

In addition, when the lid to be manufactured is for a food bottle, the wax or other pretreatment agent should be selected with due consideration to its toxicity.

2. Thermoplastic resin As the thermoplastic resin with which the cork grains are bound to form the matrix, any suitable thermoplastic resin can be used.

Most preferred for use in the present invention are low density polyethylene and ethylene copolymers having a softness comparable to that of low density polyethylene.

Comonomers in the case of copolymers include α-olefins such as propylene, isoptene, etc., vinyl esters such as vinyl acetate, acrylic or methacrylates or esters, and the like.

Particularly suitable among these are low density polyethylene and ethylene-vinyl acetate copolymers (vinyl acetate content of 2 to 40% by weight).

In addition to such ethylene polymers, propylene polymers,
Vinyl chloride polymers, conjugated diene polymers (e.g., putadiene copolymers), and other resin materials that are thermoplastic to the extent that they can be melt extruded and pressure molded by themselves or by the use of plasticity can be used. .

The term "11 thermoplastic resin" as used in the present invention does not mean only a single resin, but also includes a mixture of multiple types of thermoplastic resins.

3. Gasket type composition 1) Components The gasket type composition used in the present invention is composed of a mixture of cork particles and a thermoplastic resin as described above.

The cork grain content in this composition is between 5 and 50% by weight or between 10 and 35% by weight.

If the cork grain content is less than 5% by weight, there will be variations in the location of the cork grains when pressing to form a gasket.
The surface of the gasket feels quite rough.

On the other hand, if the weight exceeds 50%, it becomes impossible to coat the surface of the cork grains with thermoplastic resin and bond them to each other.
When the thermoplastic resin is melted, the composition lacks viscosity and has poor moldability under pressure.

It would also be difficult to substantially coat the cork grain surface with thermoplastic resin on the shaped gasket surface.

In the present invention, "a mixture of cork grains and thermoplastic resin" refers to
In addition to cases where this composition consists only of these two components, it is also intended to include those containing various auxiliary materials (generally in small amounts) that thermoplastic resins may conventionally contain.

Such auxiliary materials include other thermoplastic resins (including foamable resins) that are compatible with the thermoplastic resin used;
These include blowing agents, crosslinking agents, fillers, lubricants, stabilizers, coloring agents, and others.

Depending on the intended use, these should also be used with toxicity in mind.

2) Form 1-A gasket-forming composition consisting of a mixture of cork grains and thermoplastic resin of the present invention is not only a simple mixture of the participating components, but also a mixture of two or all of them tightly combined in advance. This also includes cases where the shape is

A specific example of the latter case is one in which all the components involved are melted and mixed to form a plate, chip, or pellet.

Regardless of the form, the composition in the present invention is formed in a molten state on the inside of the bottle cap, so the difference in form is not essential.

1. Gasket Formation The gasket forming process according to the present invention is similar to the conventional in situ formation of gaskets from thermoplastic melts, except that the thermoplastic material for gasket formation is of a composition as described above. There is essentially no difference.

Therefore, for details, for example,
5588 can be referred to.

In summary, this process involves placing a predetermined amount of the gasket-forming composition in a molten state inside the bottle cap, and pressing this molten composition against the inner surface of the bottle cap to form a gasket inside the bottle cap. Consisting of

The term "bottle cap" here refers to the cap before the casket is formed, that is, the cap or "shell."

"This composition is in a molten state" refers to the state of the molten state when it is introduced into the shell (which is usually the case).
In addition to this, it also includes a state in which it is once solidified and then remelted.

In addition to having a predetermined printing surface on its outer surface, the shell usually has an anchor coat or primer layer on its inner side.

The anchor coat or primer is, for example, a heat-sensitive adhesive, and a preferred means of providing such a layer on the inside of the shell is to pre-impose this layer on the board (blank) before forming the shell.

An example of an anchor coating agent when the thermoplastic resin is an ethylene-vinyl acetate copolymer is, for example, NPC-60 (
Product name) (Daito Paint Co., Ltd.) (epoxy phenolic adhesive varnish).

Note that the shell is usually made of metal.

The gasket-forming composition is melt-kneaded in a suitable extruder and extruded from a discharge port, and a predetermined amount of the composition is dropped into the inside of the shell.

The melt can be made into small lumps of a predetermined amount (for example, 150 to 45 omy) by cutting the extruded parison into a predetermined length or by various other suitable methods.

The composition placed in the shell is pressed in a molten state with a punch to form a gasket.

The shape of the pressing surface of the punch has been in a yin and yang relationship with the surface shape of the gasket to be formed, but the shape can be a simple flat plate, a shape with concentric ridges, or other shapes suitable for use as a gasket. It can be of various types.

Appropriate heating can be applied to the shell during pressing and/or before pressing so that the gasket-forming composition has sufficient fluidity when pressed with the punch.

A composition containing cork grains and a thermoplastic resin is heated and compressed to form a round rod or plate shape, which is then cut into disk shapes, which are inserted into the inside of the bottle lid. The gasketed bottle cap of the present invention can also be manufactured by heating the disc-shaped composition to melt it and adhering it to the inside of the bottle cap.

5. Bottle lid with gasket The bottle lid with gasket thus obtained has a structure in which a gasket formed on the inner surface is bonded to cork grains using a thermoplastic resin.

That is, as mentioned above, since the specific gravity of cork is small, the volume ratio of thermoplastic resin per cork grain is small,
Therefore, this gasket is called ``Awaokoshi'', which is made by hardening millet grains with candy.
It has a structure like.

6. Experimental Example Reference Example 1 Packing elasticity was measured for a gasket formed on a beer crown according to the present invention from a mixture of cork grains and various ethylene polymers by a normal cork disc elasticity measuring method (as an anchor coat, rKPc -60
J (trade name, Daito Paint Co., Ltd.) was used).

Packing elasticity is gasket original thickness AC mm),
Regarding the contraction width B [my] when applying pressure (136 kg/height) and the restoration width C [mm] after 300 seconds of pressure application, the contraction rate B
/A C '%) and recovery rate C/B ['%]
Indicated by

The thickness A-C is determined by measuring the thickness of the crown metal plate with the gasket adhered to the crown, and then subtracting the thickness of the crown metal plate.

From the results shown in Table 1, cork grains and low density polyethylene (PE) 1 or ethylene-vinyl acetate copolymer (E
It can be seen that the elasticity of the gasket made of the mixture with VA) is not only far superior to PE and EVA, but also equal to or greater than that of conventional cork discs.

Reference Example 2 As a gasket for bottle caps, it is necessary that the elasticity changes little over time.

The results shown in the table below show that the crown of Reference Example 1 was processed using a normal capping machine (
The gasket thickness was determined by capping with a capping force of 300 kg (weight), opening the cap one week after capping, and measuring the gasket thickness.

From the results shown in Table 2, the elasticity (recovery rate), which takes into account the temporal factors that affect the practical value of gaskets, is as follows: It can be seen that this is much better than No. 10).

Example 1 1. Manufacture Adhesive varnish rKPc-60J manufactured by Daito Paint was applied to the back side of a printing plate for crown stoppers (printed tin plate) on an actual manufacturing line, and after drying, an empty crown was prepared using a press on the actual manufacturing line.

The empty crown was heated to 120°C on a hot plate.

EVA-10V (ethylene-vinyl acetate copolymer) manufactured by Mitsubishi Yuka ■ was similarly heated to 120°C, and cork grains manufactured by Tokyo Eiyu Kogyo, which had been previously waxed (145'F paraffin), were added and mixed.

Mixing was completed in 2-3 minutes. The mixing ratio is as follows (W/W%) (Wax treatment is performed to prevent cork dust.

) After mixing, place the mixture on a pre-warmed empty crown,
It was immediately formed into a disk shape using a punch.

The amount of resin was approximately 400 mg mixture/one crown.

2. Test A performance test was conducted on the crown stopper ■ manufactured as described above.

The results are as follows, and both the sealing performance (instantaneous pressure resistance) and rotational torque are superior to the current cork crown.

As controls, (1) a conventional cork crown stopper, (2) a commercially available vinyl chloride resin sol pouring type crown stopper, and (2) a commercially available vinyl chloride resin pressed type crown stopper were used.

(1) Sealing test (instantaneous pressure test) (At least 10 kg/ffl or more, 15 kg/i or more is required.

) Instantaneous pressure resistance is 1 6. 2 kg/m2, which is higher than the current cork crown stopper and is in good condition.

(2) Rotational torque measurement test (minimum 30kg-α, 40k9-α or more 1)
Yes.

) Measured after bottling.

The rotational torque is good at 46.5kg-α.

Claims (1)

[Scope of Claims] 1 Consists of a bottle lid and a gasket formed inside the lid, which gasket connects the cork grains with a maximum dimension of 5 cm or less, and the surface of the cork grains on the surface of the gasket. 1. A bottle lid with a gasket, characterized in that it is formed from a substantially covering thermoplastic resin (however, the content of cork grains in this gasket-forming material is 5 to 50% by weight). 2. The gasketed bottle lid according to claim 1, wherein the thermoplastic resin is selected from the group consisting of low density polyethylene and ethylene-vinyl acetate copolymer. 3. A predetermined amount of a gasket-forming composition consisting of a mixture of cork grains and a thermoplastic resin is put into the inside of the bottle lid in a molten state, and this assembly is pressed against the inside of the bottle lid in a molten state to form a gasket on the inside of the bottle lid. 1. A method for producing a bottle lid with a gasket, characterized in that the gasket-forming composition is defined as follows. (1) The cork grains must have a maximum size of 5 plates or less. (2) The cork grain content in the gasket forming composition is 5
~50 weight. (3) The surface of the cork grains on the surface of the gasket to be formed should be substantially covered with the thermoplastic resin. 4. The method of claim 3, wherein the thermoplastic resin is selected from the group consisting of low density polyethylene and ethylene-hinyl acetate copolymer. 5. The method according to claims 3 to 4, wherein the cork grains are wax-treated in advance.