JPS649943B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyamide laminated sheet that has excellent properties as a packaging material. Various sheet-like molded products of polyamide resin (including so-called films, and also those stretched after molding; in the present invention, the term "sheet" includes all of these) are used as packaging materials. However, although the most commonly used all-aliphatic polyamide-based materials exhibit excellent properties such as water resistance and pinhole resistance, they have the drawback of insufficient gas barrier properties. On the other hand, as a sheet with good gas barrier properties,
m-xylylene diamine or meta/para mixed xylylene diamine and α having 6 to 12 carbon atoms,
A sheet made from polyamide containing xylylene groups obtained from ω-aliphatic dicarboxylic acid (hereinafter referred to as polyamide It has the disadvantage of being inferior. Although sheets made from mixtures of fully aliphatic polyamides and polyamide X exhibit fairly good properties, they are still not satisfactory in terms of gas barrier properties. The present inventors focused on the excellent properties of the above two types of polyamides, and as a result of repeated research aimed at providing a sheet with high physical properties that combines these advantages using these as raw materials, the following results were discovered. This led to the invention of a sheet with a laminated structure. That is, the laminated sheet according to the present invention is made of polyamide X containing 10 to 35% by weight of the above polyamide
and a fully aliphatic polyamide, and an intermediate layer made of polyamide X or a polyamide mixture containing polyamide X in an amount of 65% by weight or more. In the laminate sheet of the present invention, polyamide . Since the two types of polyamides that are the raw materials for the laminated sheet of the present invention as described above are already well known, detailed explanations of their manufacturing methods will be omitted, and specific examples of those particularly preferred in the present invention will be described below. show. Polyamide (m-xylylene/p-xylylene sebaamide) Fully aliphatic polyamide: nylon 6, nylon 66,
Nylon 6/10, Nylon 10, Nylon 12 These raw polyamides have a relative viscosity of 1.5~
3.5 is desirable. In order to manufacture the laminated sheet of the present invention from these raw material polyamides, first, a mixture of 10 to 35% by weight of polyamide X and the rest entirely aliphatic polyamide is prepared as a raw material resin for forming the surface layer. A particularly preferred composition is one containing 15 to 30% by weight of polyamide X. In this case, two or more resins may be used in combination for one or both of polyamide X and fully aliphatic polyamide. Furthermore, the compositions of the raw materials for the two surface layers may be made different, if necessary. On the other hand, polyamide
Although it is desirable to use only polyamide, other polyamides may be included as long as they are less than 35% by weight. The raw material resin for each layer also includes pigments and
Optional additives such as stabilizers, antistatic agents, lubricants, and small amounts of organic polymers can be blended. Molding can be carried out according to the usual method for manufacturing this type of laminated sheet, but the raw resin for forming each layer is melted in separate extruders, and the resulting molten resin flows are combined in a distributor. If a co-extrusion method is used in which a laminar flow is extruded through a T-die to obtain a laminated structure at once, a laminated sheet with particularly excellent performance can be obtained since there is no need for an interlayer adhesive. After forming, if the sheet is stretched at a temperature higher than the glass transition temperature of the raw material resin, a sheet with particularly excellent mechanical properties such as impact resistance and pinhole resistance can be obtained. It is desirable to stretch in both the vertical and horizontal directions.
The appropriate stretching ratio is about 6 to 15 times. Generally, biaxial stretching of a laminated sheet is often difficult, but the laminated sheet of the present invention has extremely good stretching properties. The thickness of the surface layer and the intermediate layer in the laminated sheet of the present invention is not particularly limited, but in the case of a sheet used for general packaging materials, it is desirable that the thickness be within the following range. Surface layer Intermediate layer Unstretched sheet 30-100μ 50-200μ Biaxially stretched sheet 2-15μ 5-25μ The laminated sheet of the present invention as described above has a high degree of gas barrier by making good use of the features of the two types of polyamide resins. It has excellent mechanical properties such as water resistance, pinhole resistance, and is easy to perform secondary forming processes such as stretching and deep drawing, so it can be used alone or further as needed. It is an excellent product that can be widely used as a high-performance packaging material by laminating it with other plastic sheets. Next, the present invention will be explained with reference to Examples. The evaluation of the sheet properties shown in the Examples was based on the following criteria. Gas barrier oxygen permeability [cc/ ^m2・24Hr・atm] ◎...30 or less〇...30-50 △...50-100 ×...100 or more Water resistance When immersed in water at 20℃ for 24 hours Observe changes in 〇... Slightly softened △... Softened ×... Significantly softened Stretchability Observe the behavior when stretched 3 times in the length direction at 110°C and then 2.5 times stretched in the width direction at 190°C. ◎... Smoothly stretched 〇... Can be stretched △... Uneven stretching ×... Cutting secondary formability during widthwise stretching Formed into a cup shape with a depth of 35 mm and a diameter of 50 mm using a deep drawing machine. Observe the behavior when 〇...Can be formed△...Some defective products may occur, but it can be formed for the time being ×...It can be torn and cannot be formed Pinhole resistant A load of 5 kg/cm ² is applied to a sheet that has been folded multiple times with the fold lines crossing each other. Check for pinholes that occur when adding 〇...No pinholes x...Pinholes occur Example 1 Poly(m-xylylene/p-xylylene adipamide) (copolymerization ratio of m-form and p-form 90:10, below)
PXAM) and nylon as raw materials,
Three-layer laminate sheets of various configurations were manufactured. Molding was performed by coextrusion, and the molding temperature was 250°C. The structure and properties of the obtained laminated sheet are shown in Table 1, and only those within the scope of the present invention exhibited overall excellent properties.

[Table] Examples 2 and 3 Poly(m-xylylene adipamide) (hereinafter
PmXAM) and nylon 6 as raw materials,
A three-layer laminated sheet was produced. Molding was carried out by coextrusion, and the molding temperature was 255°C. The structure and properties of the obtained laminated sheet are shown in Table 2.

【table】

[Table] Example 4 Poly(m-xylylene sebaamide) (hereinafter
PmXSM) and nylon 6 as raw materials,
A three-layer laminated sheet was produced. The molding was carried out using a coextrusion method, and the molding temperature was 240°C. Table 3 shows the structure and properties of the obtained laminated sheet. Table 3 1st layer Nylon 6 (%) 85 PmXSM (%) 15 Thickness (μ) 85 2nd layer Nylon 6 (%) 15 PmXSM (%) 85 Thickness (μ) 160 3rd layer Nylon 6 (%) 85 PmXSM (%) 15 Thickness (μ) 75 Sheet properties Gas barrier properties Γ Water resistance ◎ Stretchability ○ Secondary formability ○ Pinhole resistance ○

Claims (1)

[Claims] 1 70 mol% or more of the diamine component is m-xylylene diamine or mixed meta/para xylylene diamine, and 70 mol% or more of the dicarboxylic acid component is an α, ω-aliphatic dicarboxylic acid having 6 to 12 carbon atoms. A surface layer consisting of a mixture of xylylene group-containing polyamide and fully aliphatic polyamide in a weight ratio of 10:90 to 35:65;
1. A laminated sheet comprising an intermediate layer made of a polyamide mixture containing at least % by weight.