JPS5952917B2 - Manufacturing method for adhesive cans - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a bonded can having a side seam bonded portion that is strong and has stable bonding strength under high-speed, short-time can manufacturing bonding conditions.

In recent years, adhesive cans, which are made of tin-free steel that does not contain tin and whose side seams are joined with polymer adhesive, have become widely used for beverage cans for carbonated drinks, fruit juices, coffee, etc. It's here.

Such adhesive cans are made by fusing a film adhesive to both ends of a can body blank coated with a primer to be joined in a short period of time, and then bonding the ends of the blank to which the adhesive has been applied in a short period of time to form a can. A method of forming a can body, or by fusing adhesive or applying hot melt to one end of a can body blank coated with a primer, and then gluing the ends of the blank together for a short time to form a can body. Generally, the can manufacturing speed is 300 to 10
00 cans/min, and the adhesion time when forming can bodies by applying adhesive to the edges of can body blanks or bonding blank edges together is extremely short at 20 to 100 milliseconds. Therefore, the adhesive used must have good adhesion to each other and to the primer under such high-speed, short-time bonding conditions, and the resulting adhesive strength must be strong and stable. be done.

In addition, during the lid tightening process after the can body is formed, or the painting and baking process on the inside of the can that is carried out as necessary, the adhesion strength of the side seam may decrease or the side seam adhesion may become loose.
It is required that there is no peeling etc.

Furthermore, when filling such an adhesive can with carbonated drinks, 1
Since the double wrapping operation is performed at a relatively low temperature of 0℃ or less at high speed, the adhesive must be able to withstand rapid deformation at relatively low temperatures. The adhesive strength does not decrease during the hot bag or retort process, and micro-leakage does not occur over time due to the influence of can contents, especially contents containing acidic components, during long-term storage, and the quality of the contents is maintained. It is required that it does not reduce the

In this way, the adhesive used in adhesive cans has good short-term adhesion not only between the adhesives but also between the adhesive and the primer during the high-speed can-making process. It must satisfy a variety of physical and chemical properties required by the filling, lid-sealing process, relationship with the contents, etc.

Adhesives for adhesive cans, which require such diverse performance, have basic physical properties such that they rise above the melting point when heated in an extremely short period of time, have good wettability to the primer in the molten state, and are extremely stable when cooled below the melting point. Since it is necessary to crystallize in a short time and have strong adhesive strength, crystalline linear polyamide resins have traditionally been used as suitable materials. Japanese Patent Publication No. 50-37690, Japanese Patent Publication No. 51-18978, Japanese Patent Publication No. 1983-3
It is disclosed in Japanese Patent Publication No. 45-32359, Japanese Patent Publication No. 18096-1988, Japanese Patent Publication No. 37690-1987, Japanese Patent Publication No. 18-1988.
All of the techniques disclosed in Publication No. 978 focus on the composition and physical properties of crystalline linear polyamide resin as a means of improving adhesiveness during high-speed can manufacturing, and the techniques disclosed in Publication No. From the point of view of high-speed, short-time adhesion between a primer and a primer, the chemical properties of the polymer adhesive, which is an extremely important basic factor, have not been sufficiently investigated, and its settings are inappropriate. The adhesive strength during the can body forming process was low, and there were also problems with adhesive stability during the subsequent can inner coating baking process, lid tightening process, filling process, and long-term storage. Furthermore, JP-A No. 54-3133 relates to a hot melt adhesive in which the terminal groups of polyamide resin are controlled, and this technology is related to hot melt adhesive which requires a longer adhesion time than that used in high-speed can making. It is unclear whether it is practical as an adhesive for high-speed can manufacturing in which the adhesion time j is 100 milliseconds or less, such as in commercial can production lines.

In particular, as the demand for adhesive cans has increased in recent years, can manufacturing speeds have also become faster. There is a desire for something.

Under these circumstances, the present inventors have developed a bonded can that has highly stable adhesion in the high-speed can making process, with an adhesion time of 100 milliseconds or less in the can body forming process, and has excellent processability, heat resistance, and content resistance. In order to obtain an adhesive for high-speed can manufacturing with excellent can quality such as ω-laurolactam 85 is used as the adhesive for the side seam of the can body in the high-speed manufacturing of adhesive cans, in which the bonding time in the can body forming process is high and short, less than 100 milliseconds.
% by weight or more and 15% by weight or less of other aliphatic polyamide-forming components.
7, the terminal amino group concentration is 1.3 x 10-5 to 10.0
×10-5m01/g is formed into a film with a thickness of preferably 25 to 80μ under appropriate molding conditions, and used as an adhesive for high-speed can manufacturing. The body side seam has strong and stable adhesive strength, and there is no lifting, peeling, or cracking of the adhesive during the lid-sealing process, hot pack, retort process, etc., and there is no micro-leakage even after filling with contents and storing for a long time. The present invention was completed based on the discovery that an extremely excellent adhesive can can be obtained without any adhesive. The gist of the present invention is to form a can body by bonding edge joints of can body materials coated with a primer at high speed and in a short period of time using an adhesive. - Contains 85% by weight or more of laurolactam and 15% by weight or less of other components capable of forming an aliphatic polyamide, has a relative viscosity of 1.5 to 2.7, and has a terminal amino group concentration of 1.3 x 10-5 ~10.0×10-5m0
100 using crystalline linear polyamide resin that is 1/g
The present invention provides a method for manufacturing an adhesive can, which is characterized in that adhesive cans are adhered in milliseconds or less.

In the present invention, a specific crystalline linear polyamide resin as described above is used as an adhesive, but in such a polyamide resin, the terminal amino group concentration is particularly important in terms of high-speed can manufacturing adhesion and can content suitability. It plays a role.

Table 1 and Figure 1 illustrating it are the adhesive strength and can quality test results of crystalline linear polyamide resins with different concentrations of terminal amino groups under high-speed, short-time can manufacturing adhesive conditions and relatively long-term hot press adhesive conditions. Hail. As is clear from Table 1 and Figure 1, under hot press conditions where the adhesion time is relatively long, the terminal amino group concentration ranges over a wide range, and the dependence of the adhesive strength on the terminal amino group concentration is low. on the other hand,
Under high-speed, short-time can manufacturing bonding conditions, the dependence of the adhesive strength on the terminal amino group concentration is extremely large in the region where the terminal amino group concentration is low, and as the terminal amino group concentration increases, the adhesive strength increases rapidly, and the bond strength can be maintained for a long time. The value approaches the value of the bonding condition, and the variation in value is reduced and stabilized.

This tendency is noticeable under high-speed, short-time bonding conditions such as 100 milliseconds or less, and in high-speed can making where adhesives and primers or adhesives are bonded together, the concentration of terminal amino groups increases and stabilizes the bonding strength. However, it has an extremely large effect. This is similar to the can manufacturing process mentioned above.
The shorter the bonding time and the more unstable the bonding conditions, the more
This is thought to be because the chemical affinity of the adhesive is important among the basic properties involved in adhesion, such as self-diffusion of the polymer adhesive and wetting with the primer in the molten state, and its influence is large.

However, when the terminal amino group concentration is further increased in the above polyamide resin, the adhesive strength under high speed and short time conditions does not increase much, and on the contrary, the thermal stability of the adhesive deteriorates.
Adhesive strength decreases during can inner surface painting and baking processes after can body formation, and water resistance, acid resistance, etc. also decrease, resulting in poor content resistance. There is a suitable range for the concentration, which is practically 1.3 x 10-5 to 10.0 for the polyamide resin of the present invention.
x10-5 m01/g, which is narrower than the preferred range of hot melt adhesives disclosed in JP-A-54-3133 and the like, and is located in a relatively low amino group concentration region. Next, to explain the present invention in more detail, first, the polyamide resin composition used as the adhesive of the present invention includes ω-laurolactam alone or ω-laurolactam in an amount of 85% or more and 15% by weight of other aliphatic polyamide-formable components. % or less is preferable. If the amount of ω-laurolatatum is less than 85% by weight, the crystallinity is significantly inhibited, the melting point is lowered, and it not only takes a long time to cool down after heat bonding. It is not preferable as an adhesive for high-speed can manufacturing because the adhesive part of the side seam peels off during can inner surface correction coating after can body formation and oven drying, causing so-called shell breakage.

In addition, as the aliphatic polyamide-forming component that can be used in a range of 15% by weight or less, (a) carbon number 9
~13 ω-lactams other than laurolactam or ω-
Preferred ingredients include salts of aminocarboxylic acids or (b) aliphatic dicarboxylic acids having 6 to 36 carbon atoms and aliphatic diamines having 6 to 13 carbon atoms, or condensates thereof, and specifically, Examples of lactams or ω-aminocanolebonic acids having 6 to 13 carbon atoms include ω-caprolactam, lactofuryl lactam, 11-aminoundeganic acid, and aliphatic dicarboxylic acids having 6 to 36 carbon atoms. Examples of salts of aliphatic or aromatic diamines having 6 to 13 carbon atoms or condensates thereof include salts of adipic acid, sebacic acid, dimer acid, etc. with hexamethylene diamine, 1,11-undecane diamine, etc., or their condensates. Condensates can be mentioned.

Such polyamide-forming components are used to set the molecular weight, terminal amino group concentration, and crystallinity, transparency, melting point, etc. of the polyamide adhesive of the present invention within the preferred range of the present invention after shaping into a tape shape. , component (a) is 0 to 14% by weight,
Preferably 1 to 8% by weight, component (b) 1 to 15% by weight,
It is preferable to use it in a range of 2 to 10% by weight, and if it is used outside this range, the molecular weight, terminal amino group concentration, crystallinity, transparency,
This is not preferable because it becomes difficult to set the melting point etc. within an appropriate range and optimally exhibit adhesion, process suitability, and suitability for can contents in a high-speed can manufacturing process. Further, the relative viscosity of the crystalline linear polyamide resin of the present invention is preferably 1.5 to 2.7; if the relative viscosity is 11.5 or less, it lacks mechanical strength as an adhesive, and if it is 2.7 or more, the molecular weight is too large, the melt viscosity is too high and the adhesive strength is extremely low, which is not preferable.

In particular, the polyamide resin of the present invention has a terminal amino group concentration of 1.3
It is necessary to set it in the range of 10-5 to 10.0 x 10-5 m01/g, preferably 1.3 x 10-5 to 6.
0x10-5m01/g is suitable. 1.3×10-
If it is less than 5m01/g, the affinity for the primer painted on the stain-free steel surface will be poor, and the adhesion at high speed and in a short period of time will be poor, and in this range, the adhesive strength will be too low for practical use, causing problems. be.

Also, 6.0×10-5m01/g or more, especially 10×1
If it exceeds 0-5m01/g, it is difficult to produce such a polyamide resin stably and with good reproducibility, and the resulting polyamide adhesive also has poor thermal stability, water resistance, acid resistance, etc. If the contents are stored for a long period of time after being filled, the adhesive strength will decrease and the can may leak over time, which poses a practical problem. Known polymerization methods can be applied to produce the polyamide resin of the present invention having such characteristics, but by appropriately setting the polymerization degree regulator or polymerization reaction rate, etc., the terminal amino group concentration and relative viscosity can be adjusted to the level of the present invention. It is necessary to adjust it so that it falls within this range.

When synthesizing a polyamide with a high concentration of terminal amino groups, hexamethylene diamine, etc. can be used as a polymerization degree regulator, and when synthesizing a polyamide with a low concentration, adipic acid, etc. can be used. Polyamide with a desired relative viscosity can be synthesized by controlling the time. Furthermore, the polyamide resin of the present invention can also be produced by blending two or more types of polyamides, as long as the composition, terminal amino group concentration, and relative viscosity of the polyamide resin obtained by blending are within the scope of the present invention. Even if the composition, terminal amino group concentration, and relative viscosity of each raw material polyamide resin are outside the range of the present invention, there is no problem. If desired, it is also possible to blend a different polymer other than polyamide, such as ethylene-vinyl acetate copolymer, as a minor component, and the relative viscosity, terminal amino group concentration, etc. of the adhesive obtained from the blended resin may be As long as it is blended within the range specified by the present invention and is subsequently formed into a film, it can be used as it has preferable adhesive properties. In addition, the concentration of the terminal carboxyl group, which is the five terminal groups other than the terminal amino group of the polyamide resin, is not particularly limited, but if it becomes significantly high, the adhesion of the adhesive to the primer and water resistance will decrease, so the terminal carboxyl group concentration is not particularly limited. The base concentration is 20x10
-5 m01/g or less, preferably 10 x 10-5 m01
/g or less. Furthermore, as a method of using the crystalline linear polyamide resin of the present invention as an adhesive for high-speed can making, it is preferable to apply the polyamide resin to can body blanks. There are various methods such as applying the polyamide resin to the edges by melting it, or forming the polyamide resin into a film and adhering it to the edges of the can body blank. It is preferable to form the film into a shape and use it, and the film forming conditions at that time include appropriately setting the cooling conditions after melting the polyamide resin, and shaping the film so that the crystallinity of the film is 20 to 40%. In other words, it is desirable to use a crystalline linear polyamide resin and to cool and solidify it from a molten state to a thickness of 25 to 8 mm.
When creating a 0 μ film, if the cooling solidification temperature is high, the crystallinity of the resulting polyamide film will be high, the crystal size will be large, and the unevenness of the film surface will become large. In high-speed can making processes where films must be melted and bonded in a short period of time, bonding is performed before the crystals are sufficiently melted and activated, resulting in poor adhesion and large variations. This is not practical.

On the other hand, when the cooling solidification conditions are low, the crystallinity tends to be low, and in films with a crystallinity of 20% or less, the coefficient of static friction becomes large and the film's slipperiness deteriorates, so the film is wound. Wrinkles occur during removal, causing problems in the can manufacturing process and adhesive strength, which is not practical. Such crystallinity is also related to the transparency of the film, and in the present invention, the transparency of a 40μ thick film measured based on JIS-K-67171 is in the range of 83 to 95%, preferably 84 to 92%. By using a film, it is possible to exhibit excellent practical performance. The thickness of the film of the present invention is preferably 25 to 80 μm. If the film thickness is less than 25 μm, not only will it not be possible to obtain effective adhesive strength, but also the mechanical stress applied to the film tape during the pasting of the film tape in the above-mentioned can manufacturing process will be reduced. It is undesirable because it will succumb to the tension and stretch or break. Furthermore, if the film is over 80 μm, the film is too thick in such a high-speed can making process, and the film is not sufficiently melted due to insufficient heat being applied. Also in the seaming process, if the film is too thick, good seaming cannot be achieved and the microleak resistance decreases, which is undesirable. Next, in the present invention, metal coated with a primer, preferably stain-free steel coated with a primer, is used as the can body material, but various conventionally used primers can be used as the primer. Specifically, phenolic resin, epoxy resin, polyester resin, alkyd resin, vinyl chloride monovinyl acetate copolymer resin, polyurethane resin, acrylic resin, etc.
Among them, a thermosetting epoxy phenol resin is particularly preferred from the viewpoints of adhesion to the polyamide resin of the present invention, protective effect on metal substrates, suitability for can contents, etc. It has a suitable composition and a coating thickness of 20μ or less, preferably 0.05 to 10μ.

Such a primer has the effect of acting as an adhesion intervening layer between the adhesive of the present invention and the metal base, and at the same time has the effect of protecting the metal can stock. It is necessary to do so.

As a method for producing a can body using the can stock coated with such a primer and the polyamide adhesive of the present invention, conventionally known methods for manufacturing adhesive cans can be applied. Both ends of a can body blunter with an epoxy phenol resin primer coated on both sides of the steel are heated, a film adhesive is fused for a short time by roll pressure, etc., and the ends of the blunter with the adhesive pasted are then bonded together. After heating, the can body is compressed and cooled in a very short time using a can body forming machine to form a can body of a bonded can, or a film adhesive is fused for a short time to one end of a can body blank coated with a primer. Examples of methods include melting and applying an adhesive, then heating the ends of the blank, and then using a can body forming machine to compress and cool the can body in a very short time to form the can body of the adhesive can, but we are particular about this manufacturing method. It's not a thing.

In all of these manufacturing methods, the application of adhesive to the can body blank or the subsequent adhesion of the edges of the blanks using a can body forming machine is carried out at extremely high speed, and the time required for the adhesion in the can body forming process is 20 to 100 minutes. It takes an extremely short time of milliseconds, and the edges of the heated can body blanks are bonded together by pressure and cooling, and a side seam is formed.
The heating conditions for the edge of the blank in the can body forming process of high-speed can manufacturing may be any temperature condition that can melt the adhesive applied, and is usually 150 to 500°C, depending on the melting point of the polyamide resin of the present invention. It should be set appropriately within this range.

In addition, the pressure bonding cooling conditions are such that the adhesive on the edge of the blank and the primer or adhesive are sufficiently fused together under the above-mentioned short time conditions, and at the same time, the fused adhesive is rapidly cooled and solidified to have a strong bonding force. Any crimping cooling conditions are sufficient, and the optimum crimping force may be selected within the range of several kg/Cm2 to several 100 kg/Cnl, depending on the thickness of the can material used, can manufacturing speed, can shape, etc. It is desirable that sufficient consideration be given to the equipment so that such compression cooling can be carried out satisfactorily. The obtained can body is then blended and the bottom lid is sealed.
Then, if necessary, correction coating is applied to the inner surface of the can to obtain a can body.

The can body thus obtained had a relative viscosity of 1.5 to 2.7 using a polyamide resin containing 85% by weight or more of ω-laurolatatum as an adhesive, and a terminal amino group concentration of 1.3×1.
Because it uses a crystalline linear polyamide resin with a size of 0-5 to 10.0 x 10-5 m01/g, it has excellent adhesive strength with a high-speed bonding process of less than 100 milliseconds, and the can quality is also excellent. This makes it suitable for beverage cans, but it is also suitable for other uses such as food cans, cosmetic cans, and miscellaneous cans. The following description will be given with reference to examples, where parts are by weight. The terminal amino group is the value measured by a known measuring method, the relative viscosity (ηRel.) is the value of a 20.5% m-cresol solution at 25°C, and the crystallinity is determined by the known density method. This is the measured value. Example 1 94 parts of ω-laurolactam, 3 parts of ω-caprolactam, 3 parts of hexamethylenediamine adipate, 10 parts of water as polyamide raw materials A small amount of adipic acid or hexamethylenediamine as a polymerization degree regulator (in accordance with the present invention) In the comparative examples and examples, polyamide film numbers 1, 2, 3, 4
, 5, 6, respectively 0.25 part, 0.25 part, 0.20 part, 0.20 part, 0.05 part of adipic acid,
0.05 parts and film numbers 7, 8, 9, 10,
For No. 11, hexamethylene diamine was added to 0.
15 parts, 0.15 parts, 0.4 parts, 0.5 parts, 0.6 parts)
was placed in a high-pressure polymerization reaction vessel using nitrogen gas, and after purging with nitrogen gas, it was heated for 26 hours while depressurizing so that the pressure did not exceed 20 kg/Cm2.
The temperature was raised to 0-280°C.

After maintaining the same temperature for 4 hours under a pressure of 20 kg/Cm,
The pressure was released over time and returned to normal pressure.

Under nitrogen gas flow, the same temperature was maintained and polymerization was carried out so that the relative viscosity reached the target value. Table 1: Polymerization with different concentrations of terminal amino groups
, crystalline linear polyamide resins having film numbers 1 to 11 were produced. Then, it was melted and cooled using a press machine equipped with a T-die to form a film with a thickness of 40.0 μm. Next, coat a 0.17 mm thick stain-free steel plate with epoxy phenol so that the surface corresponding to the inner surface of the can has a film thickness of about 5 μm, and the surface corresponding to the outer surface of the can has a film thickness of about 2 μm. A 136.5 m can body material coated with a paint based on the coating and baked, and the above film adhesive was roll-bonded to the joints of both edges.
A can body blank with a size of m x 170.4 mm was created.
Next, both ends to which the adhesive has been applied are heated using a high-frequency heating method, formed into a cylinder using an ordinary can body forming machine, the ends are overlapped to a width of 5 mm, and crimped and cooled for 50 milliseconds. A can body was created under can manufacturing conditions. A 202-diameter aluminum lid was double-sealed to the resulting can body as a bottom lid, and a thermosetting vinyl chloride resin was further coated and baked on the inner surface of the can to produce a can body. This can body has a lid made from a can body material made of 0.26 mm thick tain-free steel, coated with epoxy/phenol paint and baked on the inner surface of the can body. %, and using an aqueous solution containing 3%,
Gas water with a carbon dioxide gas volume of 4.0 was double-sealed and filled to create a filled can for a time-lapse leakage test (microleak test). Using the obtained can bodies and filled cans, can body adhesive strength and microleak tests were conducted.

The storage period of the filled cans was 30 days at room temperature. Furthermore, hot press adhesive strength was measured using the above polyamide film and can body blank at a bonding time of 30 seconds and a temperature of 200°C and a pressure force of 40 kg/cm2, and compared with the adhesive strength in high-speed can manufacturing. These results are shown in Table 1 and Figure 1.

From this result, when using an adhesive made of this polyamide resin, films Nos. 1 and 2, which have a low concentration of terminal amino groups, had an abnormally low adhesive strength during high-speed can making in the can quality test (micro leak test 1). A defective can occurred. In addition, in films No. 3 to 9 of the present invention, as the terminal amino group concentration increases, the adhesive strength during high-speed can making rapidly improves, approaching the hot pressing conditions with long adhesion time, and the can quality test is also good. be.

However, film number 10,1 with a high concentration of terminal amino groups
1, it is difficult to increase the molecular weight in terms of resin production,
It is difficult to form into a film, and there are sticky eyes in the film. The adhesive strength of the resulting cans varies greatly. Micro-leak cans occur in can quality tests, and the adhesive stability during the can manufacturing process and the storage stability of filled cans are affected. It was inferior to films Nos. 3 to 9 of the present invention.

As described above, films Nos. 3 to 9 of the present invention had good practicality. Example 2 100 parts of ω-laurolactam was used as a polyamide raw material, and 0.4 parts and 0.4 parts of adipic acid were used as polymerization degree regulators, respectively.
Alternatively, a polymerization reaction was carried out in the same manner as in Example 1 except that 0.1 part was used, and then a film was formed to obtain a polyamide film having the terminal amino group concentration and relative viscosity shown in Table 2 Film No. 12 and 13. Ta.

Similarly, ω-laurolactam 9 was used as a polyamide raw material.
A polymerization reaction was carried out using 4 parts and 6 parts of ω-caprolactam, and 0.25 parts and 0.05 parts of adipic acid as a polymerization degree regulator, respectively, and then formed into a film, and the terminal amino group concentration and relative viscosity were expressed. -2 Polyamide films having values shown in film numbers 14 and 15 were obtained. Next, using these polyamide films, a can body was formed by high-speed can manufacturing in the same manner as in Example 1, and filled cans for micro-leak tests were prepared, and adhesive strength and micro-leak tests were conducted.

As a result, as shown in Table 2, polyamide films Nos. 13 and 15 of the present invention had good adhesive strength and can quality, but films Nos. 12 and 1 had a lower concentration of terminal amino groups.
Film No. 4 had lower adhesive strength than Film Nos. 13 and 15 of the present invention, and defective cans also occurred in the micro leak test.
Example 3 100 parts of ω-laurolactam was used as a polyamide raw material, 0.25 parts of adipic acid was used as a polymerization degree regulator, and the other procedures were the same as in Example 1, with a terminal amino group concentration of 1.0.
A homopolyamide with a relative viscosity of 2.2 x 10-5 m01/g was obtained.

Similarly, 80 parts of ω-laurolactam and 20 parts of ω-caprolactam were used, and 0.2 parts of adipic acid was used as a polymerization degree regulator.
A polymerization reaction was carried out using 5 parts, and the terminal amino group concentration was 1.0×
A copolyamide with a relative viscosity of 2.1 was obtained. Next, 85 parts of the homopolyamide and 1 part of the copolyamide
5 parts were melt-blended and then formed into a film with a thickness of 40μ, and the terminal amino group concentration was 1.0×10-5m01.
/g, relative viscosity 2.2, crystallinity 26%, transparency 89%
A polyamide film (film number 16) was obtained.

Similarly, using 100 parts of ω-laurolactam and 0.25 parts of adipic acid as a polymerization regulator, the terminal amino group concentration was 1.
A homopolyamide with a relative viscosity of 2.1 was obtained. Also, 80 parts of ω-laurolactam, 20 parts of ω-eprolactam, and 0.0 parts of adipic acid as a polymerization degree regulator.
Using 1 part, terminal amino group concentration 4.0 x 10-5 m01
A copolyamide with a relative viscosity of 1.9 was obtained. 85 parts of the homopolyamide and 15 parts of the copolyamide were melt-blended and formed into a film with a thickness of 40 μm and a terminal amino group concentration of 1.6×
A polyamide film (film number 17) having a crystallinity of 10-5 m01/g, a crystallinity of 26%, and a transparency of 89% was obtained. Similarly, using 100 parts of ω-laurolactam and 0.1 part of adipic acid as a polymerization degree regulator, a homopolyamide with a terminal amino group concentration of 2.7×10-5 m01/g and a relative viscosity of 1.9 was obtained. Ta.

In addition, a copolyamide with a terminal amino group concentration of 1.0 x 10-5 m01/g and a relative viscosity of 2.2 was prepared using 80 parts of ω-laurolatatum, 20 parts of ω-caprolactam, and 0.25 parts of adipic acid as a degree of polymerization regulator. Obtained.

After melt-blending 80 parts of the homopolyamide and 20 parts of the copolyamide, it was formed into a film having a thickness of 40μ, a terminal amino group concentration of 2.4×10-5 m01/g, a relative viscosity of 1.9, a degree of crystallinity of 26%, and a transparency of 89%. A polyamide film (film number 18) was obtained.

Similarly, a homopolyamide consisting of ω-laurolactam, having a terminal amino group concentration of 1.2×10 m01/g and a relative viscosity of 2.1, and 80 parts of ω-laurolactam and 20 parts of ω-caprolactam, Terminal amino group concentration4.
Using a copolyamide with a relative viscosity of 1.9 and a relative viscosity of 0x10-5 m01/g, 85 parts of homopolyamide and 15 parts of copolyamide were melt-blended and formed into a film with a thickness of 40μ and a terminal amino group concentration of 1.6x10- 5m01/g, crystallinity 26
A polyamide film (film number 17) with a transparency of 89% was obtained.

Similarly, it is made of ω-laurolactam, and has a terminal amino group concentration of 2.7 x 10-5 m01/g and a relative viscosity of 1.9.
After melt-blending 80 parts of a homopolyamide of , 20 parts of a copolyamide consisting of 80 parts of ω-laurolactam and 20 parts of ε-caprolactam with a terminal amino group concentration of 1.0×10-5 m01/g and a relative viscosity of 2.2, a film was prepared. thickness 4
0 μ, terminal amino group concentration 2.4 × 10-5 m01/g,
A polyamide film (film number 18) having a relative viscosity of 1.9, a crystallinity of 26%, and a transparency of 89% was obtained.

Next, using these polyamide films, a can body was formed under the same high-speed can making conditions as in Example 1, and filled cans for micro-leak tests were prepared, and adhesive strength and micro-leak tests were conducted. As a result, as shown in Table 2, polyamide films Nos. 17 and 18 of the present invention had better adhesive strength than Film No. 16, which had a lower concentration of terminal amino groups, and also performed well in the microleak test.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between adhesive strength, mitarolita generation rate, and terminal amino group concentration in Examples and Comparative Examples of the present invention. a...High-speed can making adhesive strength, b... Hot press adhesive strength, C... Micro leader occurrence rate of filled cans (micro leakage cans among the number of test cans) ratio).

Claims (1)

[Claims] 1. In a process for manufacturing adhesive cans in which the edge joints of can body materials coated with a primer are bonded at high speed and in a short time using an adhesive to form a can body, 85% by weight or more of ω-laurolactam and other adhesives are used as the adhesive. It consists of 15% by weight or less of an aliphatic polyamide-formable component, and has a relative viscosity of 1.5 to 2.
7, and the terminal amino group concentration is 1.3 x 10^-^
A method for manufacturing an adhesive can, characterized in that adhesive cans are bonded in 100 milliseconds or less using a crystalline linear polyamide resin having a content of 5 to 10.0 x 10^-^5 mol/g.