JP2781617B2 - Container lid with gasket - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a container lid with a gasket using a novel vinyl chloride resin composition, and particularly to a composition containing a predetermined amount of a carboxyl-modified vinyl chloride resin. The present invention relates to a container lid having excellent sealing properties at the mouth of the container and excellent adhesion of the gasket to the inner surface of the container lid base by using the gasket for a sealing gasket.

(Prior Art) In container lids such as various caps, it is necessary to provide some kind of sealing material in order to ensure sealing with a container mouth such as a bottle mouth. A plastisol in which a vinyl chloride resin is dispersed in a plasticizer can be applied to a container lid of any shape in a fluid state, and easily becomes a gasket for sealing by heating and gelling, and furthermore, like a disc-like packing. Since it is not necessary to perform the troublesome operation of punching out the packing and applying it to the container lid one by one, it is widely used as a gasket for sealing the container lid.

In the plastisol used for forming the sealing gasket, an adipate-based plasticizer such as dioctyl adipate, and a phthalate-based plasticizer such as dioctyl phthalate are generally used. As shown in JP-A-59-74148, it is also known to use a mixed fatty acid glyceride of a lower fatty acid and a higher fatty acid.

However, known plastisol compositions comprising a vinyl chloride resin and a plasticizer are not suitable for certain specific container lid applications, for example, when the skirt of the container lid is a bead with a bottle mouth. In the case of a container lid that is engaged with the bottle opening only by being wrapped around the container, the rotational torque of the container lid is too low, and the container lid rotates by hand, and the predetermined sealing performance cannot be obtained. Have.

This problem is attributable to the fact that most of the plasticizers used in plastisols have, to a greater or lesser extent, their action as lubricants, in particular with excellent hygienic properties. In the case of mixed fatty acid glycerides, since the lubricating property is excellent, the sealing performance is significantly reduced.

Further, another problem when the known plastisol composition is applied to applications such as container lids is a decrease in adhesive strength over time. That is, a gasket or the like formed by heating and gelling a plastisol shows a tendency that the bonding strength decreases over time even if it is relatively firmly bonded to a coating film such as a metal cap in the initial stage of formation. This is considered to be because the plasticizer or the lubricant in the soft vinyl chloride resin migrates to the bonding interface between the two with the passage of time, and acts to weaken the bonding strength.

Therefore, an object of the present invention is to obtain a predetermined sealing performance,
Further, it is an object of the present invention to provide a gasket-equipped container lid which does not cause the gasket to have poor adhesion over time.

(Means for Solving the Problems) According to the present invention, in the container lid comprising a container lid shell and a sealing gasket of a vinyl chloride resin composition provided in the lid shell, the sealing gasket is provided. The vinyl chloride-based resin composition comprises at least a carboxyl-modified vinyl chloride-based resin and a plasticizer, and the carboxyl-modified vinyl chloride-based resin has a carboxyl group concentration of the sealing gasket. Is provided in an amount of 2 to 20 mmol / 100 g with respect to the total composition of the above, and a mixed fatty acid ester is used as the plasticizer.

(Action) The present inventor has found that a composition comprising a carboxyl-modified vinyl chloride resin and a plasticizer provides a sealing gasket for a container lid that moderately suppresses lubricity and has little decrease in adhesive strength with time. Was.

The carboxyl-modified vinyl chloride resin used in the present invention is a carboxyl-modified vinyl chloride resin obtained by modifying an unsaturated carboxylic acid or an anhydride thereof with a vinyl chloride resin by copolymerization, graft polymerization, block polymerization or the like. And a blend of the carboxyl-modified vinyl chloride resin with an unmodified vinyl chloride resin. In each case, the carboxyl group of the modified product is 2 to 20 mmol / mole relative to the total composition. Contains 100g.

A composition containing such a carboxyl-modified vinyl chloride-based resin, a plasticizer, and optionally other components,
In particular, when a plastisol is applied to a container lid, molded and used for a gasket for sealing, the rotational torque can be maintained at an appropriate value to improve the sealing property of the container, and the adhesiveness with the base decreases over time. Can be suppressed.

In the present invention, the action of suppressing the unusual decrease in the opening torque of the vinyl chloride resin composition, or the effect of suppressing the time-dependent decrease in the adhesive strength is observed only when the above-mentioned carboxyl-modified vinyl chloride resin is used. However, ordinary vinyl chloride resins and other copolymers cannot achieve the above-mentioned effects at all.

The above-mentioned specific action and effect have been found as phenomena as a result of a number of experiments, and the reason has not yet been fully elucidated. However, the carboxyl group ( -COOH) is thought to suppress the migration of the plasticizer contained in the resin to the surface during gelation.

It is important that the resin composition of the present invention contains a carboxyl group of 2 to 20 mmol / 100 g, particularly 5 to 15 mmol / g, based on the whole composition. If the content of the carboxyl group is below the above range, the effect of suppressing the reduction in rotational torque and the effect of improving the sealing performance and the adhesive force over time cannot be sufficiently obtained. The tendency (adhesion tendency) increases and the opening performance decreases, and the tendency to absorb the moisture in the contents of the container increases.

(Preferred Embodiment of the Invention) As the carboxyl-modified vinyl chloride resin, a monomer having a carboxyl group is introduced into the main chain or a side chain of the vinyl chloride resin by means of random copolymerization, graft polymerization, block copolymerization or the like. And a modified product such as an unsaturated carboxylic acid and a derivative thereof or an epoxy carboxylic acid obtained by random copolymerization, graft copolymerization or block copolymerization in the presence of a radical initiator such as peroxide or radiation. Can be

Specific modifying monomers include acrylic acid, methacrylic acid, citraconic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, unsaturated carboxylic acids such as tetrahydrophthalic acid, maleic anhydride, itaconic anhydride, citraconic anhydride. Acids, dicarboxylic anhydrides such as tetrahydrophthalic anhydride, and unsaturated carboxylic esters such as methyl acrylate, methyl methacrylate, dimethyl maleate, diethyl fumarate, monomethyl maleate, dimethyl itaconate, and diethyl tetrahydrophthalate anhydride Can be exemplified. However, the derivative is used after the ester bond is hydrolyzed.

The carboxyl-modified vinyl chloride resin may contain, in addition to the vinyl chloride unit and the unit of the ethylenically unsaturated carboxylic acid or a derivative thereof, a vinyl monomer unit copolymerizable therewith. Examples thereof include vinyl acetate, styrene, (meth) acrylate, and vinylidene chloride.

Vinyl chloride resins for plastisols are produced by emulsion polymerization or suspension polymerization of vinyl chloride monomers. When an ethylenically unsaturated carboxylic acid or a derivative thereof is present in the initial stage, the final stage, or any of these intermediate stages of the polymerization, emulsion polymerization particles of a vinyl chloride polymer modified with a carboxyl group or Suspension polymerized particles are obtained. In this case, the carboxyl group may be uniformly present in the particles, or may be preferentially present only on the surface. The content of the carboxyl group-containing monomer per vinyl chloride resin is 2 to 20 mmol / 1.
A range of 00 g is appropriate.

Alternatively, the carboxyl group-modified vinyl chloride resin is, for example, a paint resin or an adhesive such as a vinyl chloride-maleic acid copolymer, a vinyl chloride-vinyl acetate-maleic acid polymer, or a vinyl chloride-acrylic acid copolymer. Since these resins are commercially available as resins for use, these resins can be blended with a vinyl chloride resin not modified with a carboxyl group and used for forming a plastisol. The blending can be performed by a dry method, a wet method, or a kneading method.

As a carboxyl-unmodified vinyl chloride resin,
In addition to vinyl chloride homopolymers, vinyl chloride and small amounts of comonomers, such as vinyl acetate, vinylidene chloride, styrene,
Copolymers with acrylic esters, methacrylic esters, and butadiene can also be used. The average degree of polymerization of these vinyl chloride resins is not particularly limited, and is generally 500 to 300.
A value of 0 is convenient. These vinyl chloride resins can be used in the resin composition of the present invention, even those having a relatively fine particle diameter by an emulsion polymerization method, those having a relatively large particle diameter by a suspension polymerization method, and mixtures thereof. .

The plasticizer used in the present invention is a mixed fatty acid glyceride, in particular, of the formula In the formula, ^one of R ¹ , R ² and R ³ is an acyl group derived from a saturated or unsaturated fatty acid having 6 to 24 carbon atoms and an even number of carbon atoms, and among R ¹ , R ² and R ³ Two are acyl groups derived from acetic acid or butyric acid. Examples thereof include mixed fatty acid esters represented by the following formulas, for example, diacetyl monolauryl glyceride, diacetyl stearyl glyceride, diacetyl palmityl glyceride, diclatyl monolauryl glyceride and the like. The effect of the present invention is particularly remarkable when a glycerin ester having two acetyl groups and one higher fatty acyl group (particularly a uralyl group) is used.

The plasticizer is 45 to 200 parts by weight, especially 50 to 150 parts by weight per 100 parts by weight of the total of the modified vinyl chloride resin and the vinyl chloride resin.
It is preferred to use it in parts by weight.

The vinyl chloride-based resin composition of the present invention may contain known additives such as a stabilizer, a filler, a pigment, and a foaming agent as optional components for forming a liner according to a known formulation.

For example, as a stabilizer, a metal soap-based stabilizer, an organic tin-based stabilizer, an organic phosphate stabilizer, and as a filler, calcium carbonate, finely divided silica, magnesium carbonate, talc, calcined clay, etc. Examples thereof include titanium white, carbon black, etc., and azodicarbonamide, 4,4-oxybis (benzenesulfonyl) hydrazide, etc., as foaming agents, and microcrystalline wax, paraffin wax, polyethylene wax as lubricants. , Silicone oils, fatty acid amide plasticizers and the like.

The composition of the present invention is preferably used in the form of a so-called plastisol having various components dispersed in a plasticizer and exhibiting fluidity and fluidity. An example of a suitable plastisol formulation is shown below.

Modified and unmodified vinyl chloride resin 30-70% by weight Plasticizer 30-70 〃 Stabilizer 1-5 充填 Filler 0-20 〃 Pigment 0-5 〃 Blowing agent 0-5 滑 Lubricant 0-5 プ ラ ス Plastisol By rotating the container lid shell and injecting it into the shell with a nozzle, it is applied to a portion that needs to be sealed with the container mouth. Of course, if necessary, the plastisol may be pressed by a heated press die to form a predetermined gasket shape.

The plastisol applied to the container lid and shell is then heated to cause gelation and, if necessary, foaming to obtain an unfoamed or foamed gasket.

When using a foam gasket, its apparent specific gravity should be 0.4
It is desirably in the range of 1.2 to 1.2. The production of the container lid shell can be easily carried out by subjecting the coated metal material to means known per se, for example, punch press molding and scoring.

As the metal material for forming the container lid shell, a sheet-shaped or foil-shaped untreated surface steel (black plate), surface-treated steel, or a light metal such as aluminum is used. As the surface-treated steel, chemical treatment such as phosphoric acid treatment and chromic acid treatment; chemical conversion treatment such as electrolytic chromic acid treatment; electrolytic plating treatment such as electrolytic tin plating, electrolytic zinc plating and electrolytic chromium plating; Plating treatment: A treatment which has been subjected to a hot-dip plating process such as a hot-dip tin plating process may be mentioned.

At least the surface of the metal material which is to be the inner surface of the lid is coated with a protective paint. Suitable examples of coatings include thermosetting resin coatings such as phenol-formaldehyde resin, furan-formaldehyde resin, xylene-formaldehyde resin, ketone-formaldehyde resin, urea-formaldehyde resin, melamine-formaldehyde resin, alkyd resin, unsaturated polyester. Resin, epoxy resin, bismaleimide resin, triallyl cyanurate resin, thermosetting acrylic resin, silicone resin, oily resin, or thermoplastic resin paint, for example, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer Merging partially saponified product,
Vinyl chloride-maleic acid copolymer, vinyl chloride-maleic acid-vinyl acetate copolymer, acrylic acid polymer, saturated polyester resin and the like. These fatty paints may be used alone or in combination of two or more.

These paints preferably have thermal adhesion to the soft resin of the present invention constituting the gasket, and paints containing a vinyl chloride resin component or an acrylic resin component are particularly suitable.

The application amount of the plastisol of the resin composition of the present invention differs depending on whether the plastisol is foamed or unfoamed, or the shape of the gasket, but it is generally preferable to apply the plastisol to the sealing portion with a thickness of 0.3 to 4 mm. The gelation of plastisol is 160
The heating is preferably performed at a temperature of about 280 ° C. for about 10 seconds to about 3 minutes.

The resin composition of the present invention can also be extruded into the form of a pellet, a preform, or the like in a container lid shell, and then pressed with a plunger or the like to produce a container with a gasket. In this case too, many of the advantages described above are achieved.

The container lid of the present invention is particularly effective for a type in which the sealing is performed by the lower end of the skirt of the container lid shell being wound under the bead of the container mouth. Also, when used for a roll-on cap or the like, the advantage that the opening torque can be increased and the sealing performance can be improved can be achieved.

The present invention is also useful as a plastisol or resin composition for sealing containers, various structures, various sheet packings, and the like.

(Effects of the Invention) According to the present invention, a composition comprising a carboxyl-modified vinyl chloride resin and a plasticizer or an unmodified vinyl chloride resin for adjusting the amount of carboxyl group modification in some cases was used as a container lid gasket. Therefore, it is possible to suppress the excessive slippage as seen in the abnormal decrease in the rotational torque, to improve the sealing performance, and to prevent the deterioration of the adhesive force with the base over time.

Example 1 A 0.2 mm thick aluminum plate was coated with an epoxy phenolic paint as a primer and a vinyl phenolic paint as a paint for bonding to a liner material at a temperature range of 160 ° C to 220 ° C.
The resultant was baked and dried sequentially for 10 minutes, and a cap having a diameter of 38 mm was punched out so that the surface coated with the paint became the inner surface of the cap, thereby producing a rimple cap shell. 100 parts by weight of vinyl chloride resin as a cap liner material,
After weighing 90 parts by weight of acetylated glycerin fatty acid ester as a plasticizer, 0.4 parts by weight of azodicarbonamide as a foaming agent, 5 parts by weight of titanium oxide as a filler, and 3.5 parts by weight of a stabilizer, the mixture was further added as shown in Table 1. As a carboxyl group-containing PVC resin of the present invention, Nippon Zeon Co., Ltd. 400-110A, carboxyl group concentration PVC
The plastisol was added by adding 0 to 25 mmol / 100 g per compound. Put this sol in the cap 40
Apply 0mg each in a ring, and immediately in a gas oven at 220 ° C
It was baked and dried for 1 minute, and the experimental examples 1-1 to 1-7 shown in Table 1 were performed.
(Experimental Examples 1-1 to 1-4 are examples of the present invention), and the following performance tests were performed.

1. Measurement of rotational torque value of cap A glass bottle having a capacity of 180 cc is filled with hot water of 90 ° C. so that the head space becomes 7 cc, and the cap is provided with a liner material of the composition of the examples and comparative examples shown in Table 1. Was capped, allowed to cool, allowed to stand at room temperature for one week, and the torque value when the cap was rotated was measured with a torque meter.

2. Adhesive force of baking-dried liner material To confirm the adhesive force of the ring-shaped liner material applied to the inner surface of the cap, the liner material was forcibly peeled off, and the adhesion between the liner material and the cap was observed.

3. Evaluation of openability The cap of the test product capped in the same manner as in the test item 1 was opened, and the ease of opening when opening the cap was confirmed.

4. Leak after rotation of cap (decrease in vacuum) Test sample cap is capped every second as in test item 1.
The cap was rotated at a rate of 10 kgfcm for 10 seconds, and thereafter, it was examined whether the degree of vacuum in the bottle was lower than before rotation.

From the above test results, the carboxyl group concentration was 2.0 to 2
In the range of mmol / 100 g, the rotational torque value of the cap is increased, and the adhesive force with the cap of the liner material is increased,
Even when the cap was rotated, the amount of rotation was small and there was no leakage. In the cap of the comparative example, the rotation torque value was not high, the rotation amount of the cap was large, and leakage was confirmed. When the content of the carboxyl group was large, the shape of the liner material after baking and drying was poor, the surface unevenness was remarkable, and the performance as a cap was poor.

Example 2 In the same manner as in Example 1, an epoxyphenol-based paint as a primer and a vinylphenol-based paint as a paint for bonding to a liner material were applied to an aluminum plate having a thickness of 0.2 mm from 160 ° C to 220 ° C.
Each was baked and dried in a temperature range of 10 ° C. for 10 minutes, and a cap having a diameter of 38 mm was punched out so that the surface coated with the paint became the inner surface of the cap, thereby producing a rimple cap shell. 100 parts by weight of vinyl chloride resin as a liner material for caps, 90 parts by weight of each of acetylated glycerin fatty acid ester, acetyl tributyl citrate, epoxidized soybean oil, and dioctyl phthalate as various plasticizers, and azodicarbon amide 0.4 as a foaming agent As shown in Table 2, the basic composition obtained by adding 5 parts by weight of titanium oxide as a filler and 3.5 parts by weight of a stabilizer was further added, as shown in Table 2.
400-110A of the composition of the present invention was added, and the carboxyl group concentration was 10.0 mmol / 100 g per PVC compound.
To give a plastisol. As a comparative example, a plastisol having a composition not added was also prepared. 400 mg of this sol was applied to the cap in a ring shape, and immediately baked and dried at 220 ° C. for 1 minute in a gas oven to obtain caps of Experimental Examples 2-1 to 2-8 in Table 2 (Experimental Example 2-1 was used). (Which is an example of the present invention), and the same performance test as in Example 1 was performed.

As a result, the cap provided with a gasket of a carboxyl group-containing PVC compound containing a mixed fatty acid ester (acetylated glycerin fatty acid ester) as a plasticizer according to the present invention has a higher rotational torque than the other plasticizers. The up rate was remarkably high, indicating that the effect was remarkable.

Example 3 A 38 mm rimple cap was prepared in the same manner as in Example 1. 100 parts by weight of vinyl chloride resin as a cap liner material, 90 parts by weight of acetylated glycerin fatty acid ester as a plasticizer, and azodicarbon amide 0.
8 parts by weight, titanium oxide 5 parts by weight as a filler, stabilizer 5.5
After weighing out parts by weight, further add 400-110A, add so that the concentration of the carboxyl group is in the range of 0 to 20 mmol / 100 g per PVC compound, stir with a Hensyl mixer, and pelletize with an extruder. did. The pellets were heated and melted by an extruder, cut into 600 mg pieces, pushed into a cap, and molded into a fixed shape with a mold (in-shell mold) to form a cap liner. Further, the pellet was formed into a sheet having a thickness of 1.0 mm by a sheet extruder, punched out with a punch having a diameter of 37.5 mm, inserted into a cap, and then thermocompression-bonded to remove the cap (Experimental Examples 3-1 to 3-8). Created. Example 1 of the cap
The test was carried out in the same manner as described above. As a result, similar to Example 2,
When 400-110A was added, the rotational torque of the cap was increased, and it was good without leakage.

Experimental examples 3-1 to 3-3 and 3-5 to 3-7 are examples of the present invention.

Example 4 Paint was applied to a tin plate and an aluminum plate having a thickness of 0.23 mm in the same manner as in Example 1 and sequentially baked and dried. Then, a screw having a diameter of 48 mm was applied to the tin plate so that the coated surface became the inner surface of the cap. A cap and a rug cap with a diameter of 63 mm were punched, and an aluminum plate was made of a PP cap shell with a diameter of 38 mm. As a liner material for the cap, as in Example 1, 100 parts by weight of a vinyl chloride resin, and acetylated glycerin fatty acid as a plasticizer. After weighing 90 parts by weight of an ester, 0.4 parts by weight of azodicarbonamide as a foaming agent, 5 parts by weight of titanium oxide as a filler, and 3.5 parts by weight of a stabilizer, 400-110A was added, and the concentration of the carboxyl group was determined per PVC compound. A plastisol was made to be 10 mmol / 100 g. A sol without addition of 400-110A was also prepared as a comparative column. After applying the sol in a ring shape to the cap, it was immediately baked and dried in a gas oven at 220 ° C.
To 4-6 (Experimental Examples 4-1 to 4-3 are examples of the present invention), and the same performance test as in Example 1 was performed. The bottle used for capping had a capacity of 220 cc and had a cap size suitable for the type of bottle. After filling with 90 ° C. hot water, it was kept at 90 ° C. for 5 minutes, and then cooled to obtain a test sample. As a result of the test, regardless of the type of the cap, the one in which 400-110A was added showed a good opening torque value.

Continued on the front page (72) Inventor Sumio Watanabe 2-12 Nagatoro, Hiratsuka-shi, Kanagawa Japan Inside the Hiratsuka Plant of Kuraun Cork Co., Ltd. (72) Inventor Fumio Mori 2-12 Nagatoro, Hiratsuka-shi, Kanagawa Japan Nippon Kuraun Cork Co., Ltd. Hiratsuka In the factory (56) References JP-A-1-226564 (JP, A) JP-B-48-43318 (JP, B1) (58) Field surveyed (Int. Cl. ⁶ , DB name) B65D 39/00- 55/16 C08L 27/06

Claims (1)

(57) [Claims] A container lid comprising a container lid shell and a sealing gasket of a vinyl chloride resin composition provided in the lid shell, wherein the vinyl chloride resin composition constituting the sealing gasket is: At least a carboxyl-modified vinyl chloride resin and a plasticizer are contained, and the carboxyl-modified vinyl chloride resin has a carboxyl group concentration of 2 to 20 mmol / 100 g per the entire composition of the sealing gasket. A container lid with a gasket, wherein the mixed fatty acid ester is used as the plasticizer.