JPH0367639A - Manufacture of transparent polyamide molded - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a transparent molded product, which is characterized in that a molded product made of a specific polyamide is treated in a hot water or steam atmosphere, and then dried at a certain temperature or higher. This invention relates to a method for producing polyamide molded products. More specifically, the present invention relates to a method for producing a polyamide molded article that maintains an excellent appearance such as transparency even after being treated for purposes such as sterilization, and also has excellent gas barrier properties.

[Conventional technology]

BACKGROUND ART Conventionally, plastic containers have been widely used in various fields due to their hygienic properties, fragrance retention, light weight, and low cost.

Among them, materials with excellent transparency include polyethylene, polyvinyl chloride, polyethylene terephthalate, polycarbonate, and the like.

However, containers made of polyethylene and polyvinyl chloride have extremely low heat resistance. Furthermore, containers made of polyethylene terephthalate do not have the heat resistance to withstand boiling water, and also have insufficient gas barrier properties. Furthermore, containers made of polycarbonate have sufficient heat resistance but extremely low gas barrier properties.

On the other hand, polyamide (referred to as aromatic polyamide (A)) consisting of aliphatic diamine, isophthalic acid, and terephthalic acid has transparency, heat resistance, and gas barrier properties that were not possible with conventional technology. It was developed as a material (Special Publication Showa Xis-λ1l16), and its excellent properties are used to make injection molded parts for automobile parts, electrical equipment parts, etc., film for food packaging, etc., and bottles for various containers, etc. It became possible.

[Problems to be solved by the present invention]

However, aromatic polyamide (A) has poor hot water resistance, and when immersed in hot water or kept in a steam atmosphere for purposes such as sterilization, it whitens and loses its appearance, which limits its field of use. .

[Means to solve the problem]

The inventors of the present invention have made extensive studies to obtain molded products that are free from whitening caused by such treatments as hot water immersion, and have found that by heat-treating molded products made of a specific polyamide at temperatures of 50°C or higher after whitening, excellent transparency can be obtained. The inventors have discovered that it is possible to obtain a molded article that also has heat resistance and gas barrier properties, and have arrived at the present invention.

That is, the present invention provides a polyamide-forming component consisting of an aliphatic diamine and isophthalic acid and/or terephthalic acid!
polyamide-forming component consisting of 0-700% by weight, lactam or aliphatic diamine and aliphatic dicarboxylic acid go
Thickness of polyamide (A) formed by polymerizing -o wt % or a composition formed by mixing the polyamide (A) to 50 wt % and aliphatic polyamide (Boo-go wt %!r) The present invention relates to a method for producing a transparent polyamide molded product, which comprises immersing a -500 pm molded product in hot water or treating it in a steam atmosphere, and then drying it at a temperature of 50° C. or higher.

The whitening phenomenon of plastics has been known for various plastics, but it has never been considered that once the whitening phenomenon occurs, it becomes transparent again. The effect of this invention is that aromatic polyamide (A)
For certain plastics, preferably above j O℃! This is something that can only be obtained by drying under special conditions of S° C. or higher, and it is different from conventional techniques.

The present invention will be explained in detail below.

Polyamide (A) constituting the polyamide molded article of the present invention
is a polymerization or co-polymerization of a semi-aromatic polyamide-forming component (component a) from an aliphatic diamine and isophthalic acid and/or terephthalic acid, and a lactam or an aliphatic polyamide-forming component (component b) from an aliphatic diamine and an aliphatic dicarboxylic acid. It polymerizes.

Specifically, the aliphatic diamines used in the present invention include straight chain aliphatic diamines such as ethylene diamine, tetramethylene diamine, hexamethylene diamine, octamethylene cyanine, decamethylene diamine, and methylated thereof;
Contains derivatives such as ethylation and halides,
One or more of them can be used in the polymerization.

Specifically, the lactam that can be used in the present invention includes caprolactam, lauryllactam, etc., and one or more of them can be used in the polymerization.

Aliphatic dicarboxylic acids that can be used in the present invention specifically include succinic acid, glutaric acid, adipic acid, pimelic acid, superric acid, azelaic acid, sebacic acid, and derivatives thereof such as methylated, ethylated, and halogenated substances. In the polymerization, one type or two or more types thereof can be used.

The ratio of isophthalic acid and terephthalic acid used in component a is arbitrary, but preferably the weight ratio is isophthalic acid:terephthalic acid = 20:10 to 10 = 20, particularly preferably Sθ:Sθ to 0:20. Moreover, it is preferable that the amount of component a is equal to or greater than the weight of S based on the total polyamide component.

In other words, if the a component is less than S weight%, the gas barrier property
Heat resistance etc. become insufficient.

The polyamide used in the present invention is usually produced by the so-called melt polymerization method by adding lactam to a nylon salt consisting of diamine and dicarboxylic acid or an aqueous solution thereof, if necessary, but depending on the composition of isophthalic acid and terephthalic acid, the polyamide or manufactured by interfacial polymerization method. If necessary, during polymerization, polymerization terminal terminators such as monocarboxylic acids and monoamines, heat stabilizers such as phosphoric acid esters, surfactants, antifoaming agents, antioxidants, antiblocking agents, pigments, etc. may be added. Can be mixed.

Examples of the aliphatic polyamide (B) constituting the polyamide molded article of the present invention include nylon 6, nylon-6, A, nylon-6, IO, nylon Otsu/Otsu, Otsu copolymer, and nylon-Al4.10 copolymer. Examples include combination.

Next, the mixing ratio of component (A) and component (B) is 100-! ; 0% by weight, component (B) is O to 50% by weight
and preferably component (A) is 100 to gO wt%,
Component (B) is 0 to 20% by weight. (A) Ingredients are 0.
If the amount is less than 2% by weight, the transparency after drying treatment will not be sufficient.

Polyamide (A) containing aromatic groups and aliphatic polyamide (
The mixing method (B) is usually a method of sufficiently mixing each nitrogen or melting and kneading the same one or more times using an extruder or the like, but is not particularly limited to these methods.

If necessary, heat stabilizers such as phosphate esters, surfactants, antioxidants, anti-blocking agents, pigments, etc. may be added when mixing polyamide (A) and polyamide (B) or during molding. I can do it.

The molded article in the present invention has a thickness of 5 mm and is molded by various known methods such as injection molding, extrusion molding, blow molding, and compression molding.

It is a μm molded product. If the thickness is less than S μm, it is difficult to mold, and if it is thicker than 50 μm, the whitening phenomenon is not noticeable, so the effect of the present invention is insufficient.

Specific examples of molded products include three-dimensional molded products, films, sheets, pipes, containers, etc., but the effects of the present invention are particularly large on films with a large specific surface area, blown containers, etc. Among these, the effect is particularly great for films.In this case, there are no particular limitations on the film forming method, and the solution casting method, melt extrusion method, calendar method, etc. that are generally used as resin film forming methods can be used. It is. Alternatively, a stretched film obtained by stretching these by a known method may be used.

Further, if necessary, at least one side of the film may be made of other resin such as polyamide, polyolefin, polyester, modified polyolefin, etc. by coextrusion or lamination.

The immersion treatment in hot water as used in the present invention is carried out for the purpose of sterilization, removing curls from multilayer films, etc., and usually means immersion in hot water of IAO'C or higher for 10 seconds or more. Treatment in a steam atmosphere is also carried out for the same purpose,
Normally atmosphere VCi above 110°C and gOXRH
It means to hold for o seconds or more.

In the present invention, drying treatment at a temperature of 5so℃ or higher means blowing a gas such as air at a temperature of 50℃ or higher onto a molded product, treatment with hot air to maintain the molded product at a temperature of 50℃ or higher, or molding into a closed container. After adding the product, the temperature of the molded product should preferably be at least so'c! ! It is important to keep the temperature above °C; the effects of the present invention cannot be obtained simply by applying heat at a low temperature.

In addition, since unnecessarily increasing the temperature will lead to deterioration of the physical properties of the molded article, the temperature is preferably lower than the Tg of the molded article by at least S'C.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

The measurement items in the examples were carried out by the following methods.

(1) ηrel Measured using an Ostwald viscosity tube according to JIS K-t, gto.

(2) Tg (glass transition temperature) determined by differential scanning calorimetry.

(3) Haze Measured using a haze meter according to JIS K-t, qtlI.

(4) Oxygen permeation amount Modern Contro1 0XTRAN TW
Using IN, 23℃, 9! r91;RH,! ;crA
Measured at

Example 1 A hexamethylene diamine aqueous solution (theta
wtX ) /, 7.9 Kg, isophthalic acid 9. gf
.

Terephthalic acid a and qKy were added, stirred and dissolved uniformly, and acetic acid S3f was added, followed by charging into an autoclave 7. λ
,-! While maintaining the pressure at 1-Kf/-, water is distilled out until the concentration of nylon salt becomes 20% by weight, and then tJK
After increasing the pressure to y/cd, further water is distilled out to bring the internal temperature to 23
Once the temperature reaches 0°C, slowly release the internal pressure and the final temperature is 70θ.
After polymerization was carried out under reduced pressure of torr for 1 hour, it was extruded into chips. The polymer thus obtained is η
rel, 2. ．． 2. Tgl was 7°C. This polyamide (A) was coated at a barrel temperature of 25
A transparent film (A) having a thickness of 50 μm was obtained by forming a film under the conditions of 0° C., a die temperature of 2Sθ° C., and a take-up speed of sm/min. This film (A) was used to obtain a film (B) with a 10cm angle. After removing the jig, this film (B) was placed in a hot air open air atmosphere at 6θ°C and dried for 10 minutes to obtain a transparent film (C).

Example: Polyamide (A) go weight (X) obtained in the same manner as in Example 1 and 20% by weight of nylon 6 (manufactured by Mitsubishi Kasei, trade name Novamid 1O3QCA) as polyamide (B) were made into chips in a V-shaped tumbler. - was mixed with polyamide (A) in the same manner as in Example 1, and films (D), (E), and (F) were used in place of films (A), (B), and (C), respectively. ) was obtained.

Example 3 Polyamide (4) obtained in the same manner as in Example 1 was molded using a single-layer blow molding machine (manufactured by Japan Steel Works, Model NB, 7B-B50) at a resin temperature of 21.0°C and an extrusion amount of kg. / h r
I pushed out the parison. By putting this parison into a mold and blowing it with air, it is possible to create a mold with a thickness of 100μ and an internal volume of lθ.
A container of θθd was molded. A square with an iocm angle was cut out from this container to obtain a bottle (A). Example 1
The film (B) was processed in the same manner as the film (A).
, bottle (B), bottle (C) instead of film (C)
) I got it.

Example TeiInstead of drying in an atmosphere of 6θ℃ in Example 1, gO
A similarly transparent film (G) was obtained instead of film (C) by processing in an atmosphere of .degree.

Comparative Example 1 Instead of drying in a 60°C atmosphere in Example 1,
Drying treatment was carried out in an atmosphere of 0.degree. C. to obtain a film (H) that remained white instead of film (C).

Comparative Example Example 2 The same process as in Example 2 was carried out except for mixing polyamide (A) l o wt % polyamide (s) b o wt %, and instead of film (D) (E) (F). Films (1) (J) (K) were obtained. Film (I), transparent film (J), and film (K) were both whitened to some extent, and there was no difference in appearance.

Comparative Example 3 The same treatment as in Example 1 was carried out using the polyamide (B) of Example 2 instead of the polyamide (A) of Example 1, and the film (A) (B) (C) was replaced with the film ( L
) (M) (N) were obtained.

Films (L), (M), and (N) all showed slight whitening, but there was no significant difference between them.

Table 1 shows the results of measuring the haze of the films or bottles obtained in Example/-+ and Comparative Examples/--3 above.

In addition, the film after drying, that is, the film of Example 1 (
C) The results of measuring the amount of oxygen permeation of the film of Actual M Example (F), the film of Actual TLX Example (G), the film of Comparative Example (K), the film of Comparative Example 3 (N) are shown in the same table. Shown below.

[Effects of the Invention] According to the manufacturing method of the present invention, a transparent polyamide molded product having both heat resistance and gas barrier properties can be obtained. In particular, since the whitening phenomenon after sterilization is eliminated, it is suitable for packaging materials for foods, medicines, etc. that require sterilization and transparency.

Claims (1)

[Claims] (1) By polymerizing 50 to 100% by weight of a polyamide forming component consisting of an aliphatic diamine, isophthalic acid and/or terephthalic acid, and 50 to 0% by weight of a polyamide forming component consisting of a lactam or an aliphatic diamine and an aliphatic dicarboxylic acid. polyamide (A) or the polyamide (A) 1
Thickness: 5-500μ consisting of a composition formed by mixing 0-50% by weight of 0-50% by weight of aliphatic polyamide (B) and 0-50% by weight of aliphatic polyamide (B)
The molded product of m is immersed in hot water or treated in a steam atmosphere, and then dried at a temperature of 50°C or higher,
Method for manufacturing transparent polyamide molded products.