JPS623172B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a novel copolyamide resin.
More specifically, the present invention relates to 6-12 salts and carbon atoms having 6 to 6 carbon atoms.
This invention relates to a copolyamide resin obtained by copolymerizing 13 lactams or ω-aminocarboxylic acids in a weight ratio of 90 to 65:10 to 35. The copolyamide resin of the present invention has been found to be useful as an adhesive for metals, especially as an adhesive for the side seams of metal cans that require high-speed adhesive performance, but it is also expected to be applied to various other uses. obtain. [Prior art and problems] As is well known, there has been a shift from the traditional soldered seam, or tin can, to tin-free TFS (Tein Free Steel) cans, and at the same time, the seam method has changed from the traditional soldering to adhesive. We are forced to change to a seam method using adhesive bonding. Since the can manufacturing speed is high at 500 to 1000 cans/min, it is necessary to bond in a short time of around 100 milliseconds/can, and the resulting adhesive strength must be strong and stable. . Patent publications relating to adhesive compositions for achieving this purpose include, for example, the Patent Publication No. 45, which uses polylaurin lactam (hereinafter abbreviated as nylon 12 homopolymer) obtained by ring-opening polymerization of laurin lactam alone. Publication No. 32359, Tokko Sho, which blends 89 to 60 parts by weight of nylon 12 homopolymer with 11 to 40 parts by weight of a copolyamide copolymerized from laurin lactam and other polyamide-forming substances.
50-37690, or nylon 12 homopolymer with semicrystalline polyamide or amorphous polyamide (e.g. Versalon derived from dimer acid,
Japanese Patent Publication No. 18096/1989, which blends polyamide (commercially available under the trade name Versamide) at a weight ratio of 99-90:1-10, or 98-90 parts by weight of lauryl lactam and other substances capable of forming polyamides. There is Japanese Patent Publication No. 51-18978 regarding a crystalline polyamide copolymerized with 2 to 10 parts by weight. However, each of the above conventional techniques has its own advantages and disadvantages. In other words, when the nylon 12 homopolymer disclosed in Japanese Patent Publication No. 45-32359 mentioned above is used alone, in such high-speed adhesion, it is generally necessary to prevent the elution of iron from the contents and to prevent corrosion of the casing itself. For this purpose, a phenol or epoxy paint is applied by baking to the entire inner surface of the can, but because the adhesion to the painted surface is insufficient, high adhesive strength cannot be obtained, and the nylon 12 homopolymer film itself is relatively hard. Moreover, since the elongation of the film is not very large, cracks may occur in the film during the lid tightening step performed after side sealing, which is undesirable as it may cause leakage of the contents. In order to improve this shortcoming, the above-mentioned special public service
For example, as seen in Japanese Patent Publication No. 18096 and Japanese Patent Publication No. 50-37690 listed in 1983, for example, nylon 12 homopolymer is blended with a low melting point amorphous polyamide or a copolyamide of lauryl lactam and other polyamide-forming substances. , attempts have been made to improve the adhesive strength with paints. However, in both cases, it is difficult to blend uniformly and there are large variations in adhesive strength, and the high cohesive force of nylon 12 homopolymer is reduced, preventing uniform crystallization. If it is not lowered and cooled sufficiently, the seam part will float during the cooling process, resulting in a lack of high-speed adhesion performance. In addition, as seen in Japanese Patent Publication No. 51-18978, there is a crystalline nylon 12 copolymer made by slightly copolymerizing other polyamides in order to overcome the common drawbacks of the above blends, but it is true that The adhesive strength with the paint is high, but at the same time the melting point and crystallization temperature are lowered. A drying oven for the spray coating process (spray coating with lacquer made by dissolving copolymer resin)
The disadvantage is that the seams tend to peel off when dried with hot air at 160-170°C for approximately 5 minutes. [Means for solving the problem] As a result of intensive research efforts, the present inventors have discovered ()
6,12 salt (equimolar salt of hexamethylene diamine and dodecanedioic acid) and (2) other polyamide-forming substances other than 6,12 salt and having 13 or less carbon atoms in a weight ratio of 90 to 65:10. ~35, preferably 85-70:15
The copolyamide resin, especially the crystalline copolyamide resin, which is copolymerized to have a molecular weight of ~30% has extremely high and stable adhesion to paint, and there is no cracking of the adhesive film during the lid seaming process. Moreover, there is no phenomenon such as lifting or peeling of the seam in the drying oven after the inner surface is coated.
Moreover, it has been found that extremely high-speed adhesion is possible. That is, the present invention involves copolymerizing () 6-12 salt and () lactam or ω-aminocarboxylic acid having 6 to 13 carbon atoms in a weight ratio of 90 to 65:10 to 35, and The present invention provides a method for producing a copolyamide resin, characterized in that the copolyamide resin has a relative viscosity of 1.70 to 2.40 in a 0.5% m-cresol solution. Copolyamide resins of the present invention with a relative viscosity (η _reL value) of 1.70 or less, which indicates the degree of polymerization, lack mechanical strength as an adhesive, while those with a copolyamide resin of 2.40 or more have too high a molecular weight. The melt viscosity (η _n value) is too high and it lacks affinity with paint during adhesion, making it impossible to obtain high adhesive strength. Furthermore, the proportion of lactam or ω-aminocarboxylic acid having 6 to 13 carbon atoms in the copolyamide is preferably 10 to 35% by weight, preferably 15 to 30% by weight, and less than 10% by weight is preferable. If it exceeds 35% by weight, the melting point will drop significantly, resulting in a lack of heat resistance as an adhesive, which is not preferred. Examples of lactams or ω-aminocarboxylic acids having 6 to 13 carbon atoms include laurin lactam, caprolactam, capryllactam,
Examples include ω-aminocapric acid, ω-aminopelagoic acid, ω-aminoundecanoic acid, and ω-aminotridecanoic acid. The copolymerization reaction to obtain the copolyamide of the present invention is carried out by heating a monomer consisting of a 6-12 salt and a lactam or ω-aminocarboxylic acid having 6 to 13 carbon atoms together with water, and then removing the water. be exposed. That is, to these nylon monomers, lactams, or nylon salts, several percent to several tens of percent of water and optionally catalysts such as acids and alkalis, and molecular weight regulators such as acetic acid are added, and the mixture is heated at 200°C to 300°C for 1 hour. Heat for ~20 hours. Since the equilibrium between amine/carboxylic acid and amide/water is toward the amide/water side, relatively low molecular weight polymers are produced even in the presence of a large amount of water. Water vapor is then gradually released over several hours, and condensation is further carried out at a temperature of 200° C. to 300° C. for several hours under normal pressure or reduced pressure to obtain a polymer copolyamide. Phosphoric acid or the like can be used as a catalyst, and diamines such as hexamethylene diamine and acetic acid, as well as dibasic acids such as adipic acid and dodecanedioic acid can be used as molecular weight regulators. The copolyamide resin according to the present invention has a higher elongation at break and is more flexible than the prior art, so that no cracks occur during the process of tightening the lid. Moreover, it has an ideal melting point of 170 to 200°C, which is almost the same as that of the prior art, and is fully applicable to high-speed bonding, making it very useful as an adhesive. [Example] The present invention will be described below with reference to Examples and Application Examples, but the present invention is not limited to these Examples. Examples 1 to 3 and Comparative Example 1 Monomers in the amounts shown in Table 1, 400 g of water, 8 g of 1% phosphoric acid as a condensation polymerization catalyst, and 4 g of adipic acid as a molecular weight regulator were charged, and the pressure was reduced to 10 mmHg.
Nitrogen with a purity of 99.9999% or higher was repeatedly injected at 30 kg/cm ² , and finally the autoclave was replaced with nitrogen by equalizing atmospheric pressure. The temperature of the autoclave was raised to 230° C. over 3 hours, and the monomers, etc. were melted and dissolved during this time, and stirring was started when there was no longer any resistance to stirring. The autoclave was further heated to 280° C. over 2 hours, and during this time the pressure inside the autoclave was released to 25 kg/cm ² .
After maintaining the pressure of 25Kg/ ^cm2 at 280℃ for 15 hours,
The temperature was lowered to 250℃ while the pressure was released to atmospheric pressure over time, and the nitrogen was flowed at 100ml/min.
Stirring was continued for an additional 2 hours at °C. The polymer was drawn into strands through a hole at the bottom of the autoclave using nitrogen pressure and cut into pellets. The pellets were placed in a rotary vacuum dryer with an internal volume of 20, and after purging with nitrogen, the mixture was heated to 150° C., and while the vacuum dryer was rotating, nitrogen was continued to flow at 50 ml/min to carry out solid phase polymerization. Sampling was carried out approximately every 4 hours, and the relative viscosity in 0.5% m-cresol was measured at 25°C, and solid phase polymerization was stopped when the relative viscosity exceeded 1.90.

[Table] Table 2 shows the sample numbers, compositions, and thermal properties of adhesives prepared to compare various performances.

【table】

[Table] From Table 1, No. 1, ie, nylon 12 homopolymer, has thermal properties that are suitable for the purpose of high-speed adhesion of can side seams. No.2
has a low melting point and lacks heat resistance as an adhesive.
No. 3, No. 4 and No. 6, that is, examples according to the present invention, have the advantages of nylon 12 homopolymer in terms of thermal properties and are suitable for high-speed bonding. It shows. No. 5, a copolyamide consisting of 50 parts by weight of 6.12 salt and 50 parts by weight of laurin lactam, has a low melting point and cannot be used for this purpose due to its heat resistance. Application Example 1 Table 3 shows the values of breaking strength, breaking elongation, and elastic modulus of the five types of resins No. 1 to No. 5 listed in Table 2.

[Table] From Table 3, No. 1 and No. 2, that is, nylon 12 homopolymer, or No. 3 and No. 4, that is, 85 parts by weight of 6.12 salt and laurin lactam 15 The crystalline copolyamide according to the present invention comprising 70 parts by weight of 6·12 salt and 30 parts by weight of laurin lactam has a high elongation at break and a low modulus of elasticity. This has the advantage that cracks in the adhesive film are less likely to occur because, as mentioned above, the processability is excellent during the seaming process of the lid performed after side seaming. In addition, No. 5, that is, a mixture of 50 parts by weight of 6.12 salt and 50 parts by weight of laurin lactam, is no longer a crystalline copolyamide, but becomes an amorphous copolyamide, and the breaking strength and
Both the elongation at break and the modulus of elasticity are also reduced so much that the mechanical suitability deteriorates significantly, making it difficult to use. Application example 2 Using the five types of resin pellets shown in Table 2,
An 80 m film was produced using a 40 mm extruder equipped with a T-die. Next, a 0.27 mm thick TFS plate was coated with epoxy/phenolic resin to a dry thickness of 5 μm and baked at 200°C for 10 minutes, and each adhesion test was conducted between the coated TFS plates. Sandwich the film and use a hot plate press, pressure = 20
Kg/cm ² and time = 1.0 seconds were kept constant and the temperature was varied for hot melt bonding. Table 4 shows the T-peel strength and its variation in the normal state of these adhesive samples, and the T-peel strength after thermal history at 165℃ for 5 minutes.
- Indicates peel strength.

[Table] From Table 3, sample number 1, ie, nylon 12 homopolymer, has low adhesive strength, especially at low temperatures, and has large variations. Sample number 2: 96 parts by weight of laurin lactam and 4 parts by weight of caprolactam
Crystalline copolyamides consisting of parts by weight have a stable and high adhesive strength from low to high temperatures, but have the disadvantage that the adhesive strength decreases significantly after thermal history and lacks heat resistance. Sample numbers 3 and 4, that is, crystalline copolymerized by polymerizing 85 parts by weight of 6.12 salt and 15 parts by weight of laurin lactam, and 70 parts by weight of 6.12 salt and 30 parts by weight of laurin lactam, according to the examples of the present invention. Polyamide has a stable and high adhesive strength from low to high temperatures, and there is very little decrease in adhesive strength after heat history, making it an ideal adhesive for can side seams. Sample No. 5, a copolyamide polymerized from 50 parts by weight of 6.12 salt and 50 parts by weight of laurin lactam, has a stable and high adhesive strength from low to high temperatures, but the adhesive strength decreases after heat history. It is difficult to put it into practical use due to its heat resistance.

Claims (1)

[Claims] 1 () 6・12 salt and () lactam or ω-aminocarboxylic acid having 6 to 13 carbon atoms in weight ratio
Copolymerize in a ratio of 90-65:10-35 and heat at 25℃
A method for producing a copolyamide resin, characterized in that the copolyamide resin has a relative viscosity of 1.70 to 2.40 in a 0.5% m-cresol solution.