JPS6036941B2 - Method for manufacturing barrier multilayer molded product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In the production of a multilayer molded product containing a nitrile-containing resin and an olefin-based resin, the present invention uses polyisobutylene at the interface between the nitrile-containing resin and the olefin-based resin in order to provide strong adhesion between the two. Alternatively, it is characterized by melt-bonding an isobutylene copolymer.

BACKGROUND OF THE INVENTION Conventionally, olefin resins are generally highly flexible, have high impact resistance, and have good cold resistance, and are widely used as packaging materials in various molded forms such as blow molding, sheets, and films.

However, olefin resins have a high permeability to inorganic gases such as oxygen and carbon dioxide, and organic gases such as hydrocarbons, and are not used in packaging fields such as food, pharmaceuticals, and cosmetics that require gas barrier properties. The reality is that there is no such thing.

On the other hand, nitrile-containing resins with a nitrile-containing resin content of 5% by weight or more have extremely good gas barrier properties against inorganic gases and organic gases, but cannot be said to have sufficient barrier properties against water vapor compared to olefin resins.

Furthermore, molded products with high rigidity and thick walls generally lack flexibility and have insufficient impact resistance. Therefore, as a method of making use of the characteristics of both resins and compensating for their shortcomings, a method of laminating both resins in layers to form a composite may be considered.

However, such nitrile-containing resins and olefin resins have poor compatibility, and there is no known method for bonding these resins together under industrially satisfactory conditions.

In other words, for example, in the so-called lamination method, in which pre-formed layered products are bonded together using an adhesive, the form is limited to sheet film-like molded products, and the adhesive used has various performance limitations. In addition, the adhesive itself is expensive, and the bonding operation is complicated, which is disadvantageous in terms of manufacturing and cost.

On the other hand, the method of bonding resins in a molten state is generally simple and economically advantageous, but even if you attempt to bond a nitrile-containing resin and an olefin resin by hot melting, there will be insufficient bonding between the two resins. Melt adhesion methods such as co-melt extrusion could not be applied because sufficient adhesive strength could not be obtained. The present invention enables melt bonding of both resin layers by interposing a layer of polyisobutylene or isoptylene copolymer between the two resin layers when melt bonding a nitrile-containing resin and an olefin resin. Good processing and moldability of the resin are not impaired, multilayer molded products with good thermal stability and no coloration can be easily obtained, and have high barrier properties against gases such as inorganic gases, organic gases, and water vapor. We also found that it has high mechanical strength.

The present invention will be explained in detail below.

The nitrile-containing resin used in the present invention is one containing at least acrylonitrile, methacrylonitrile, or both as a resin constituent unit, and includes random copolymers, graft copolymers, flock copolymers, and alternating copolymers. Each of these polymers or a mixture of one or more of these copolymers.

In cases other than graft copolymers, the total amount of acrylonitrile and methacrylonitrile is 5% in the resin constituent units.
It is within the range of 0 to 85% by weight, and in the case of a graft copolymer, it is within the range of 50 to 85% by weight in the monomer to be grafted. This is because gas barrier properties are insufficient if the amount is less than 5% by weight, and if it is more than 85% by weight, the melt viscosity of the copolymer is high and it is difficult to mold the copolymer using normal processing methods. This is because co-melt extrusion with other resins is difficult.

When the nitrile-containing resin is a graft copolymer consisting of a rubber backbone polymer and a polymer grafted thereto, or a mixture of the graft copolymer and another copolymer, the amount of rubber is 2% in the nitrile-containing resin. % by weight or less, and known rubber components such as Jen rubber and acrylic acid ester rubber can be used as the rubber component.

This is because if the content exceeds 2% by weight, the barrier properties will be greatly reduced.

It goes without saying that the nitrile-containing resin may contain various additives in addition to the resin. The olefinic resin is a homopolymer of Q-olefin or a copolymer of Q-olefin and other polymerizable monomers.

Examples of Q-olefins include ethylene, proprene, and putene, and examples of monomers that can be copolymerized with 4 include vinylesters represented by the formula CH2=CHOOCR (R is an alkyl group having 1 to 18 carbon atoms);
2=Acrylic acid or acrylic acid ester represented by CHCOOR (R is hydrogen or an alkyl group having 1 to 4 carbon atoms). When this comonomer is a vinyl ester, a copolymer obtained by saponifying part or all of the vinyl ester,
For example, ethylene-pinyl alcohol copolymers are also included.

When the comonomer is acrylic acid or acrylic acid ester, so-called ionomers that are ionically crosslinked with metal ions such as alkali metals and alkali metals are also included. Next, the polyisobutylene or isoptylene copolymer layer that is co-melt extruded and exists in a layered form between the nitrile-containing resin layer and the olefin resin layer and firmly adheres the two resins is made of either polyisobutylene or isobutylene copolymer, or both. It is a mixture containing 1 part of SPudin.
The average molecular weight according to the Ger (Studinger) viscosity formula is 2.0×1 pi to 1.0×1 pi.

This polyisobutylene or isoptylene copolymer has extremely good thermal stability and does not become colored when heated, so it is suitable for co-melt extrusion. A suitable monomer to be copolymerized with isobutylene in the isobutylene copolymer is, for example, isobutylene.

This polyisobutylene or isoptylene copolymer has a molecular weight of less than 2.0
The melt viscosity of No. 1 is less than 1.0 The layer thickness is insufficient to provide sufficient adhesive strength between both resins.

On the other hand, when the molecular weight is 1.0 x 1 or more, the melt viscosity is 5.
0x1 pipoise or more, and the polyisobutylene or isobutylene copolymer itself does not have sufficient adhesive strength to bond the nitrile-containing resin and the olefin resin, or melt fractures occur during co-melt extrusion, resulting in adhesion. It is difficult to form a uniform layer between both resins, and a multilayer molded product that can be put to practical use cannot be manufactured. The thickness of the polyisobutylene or isobutylene copolymer layer present between the two resins to be bonded is preferably 5 mm or more, particularly 10 mm or more in order to provide sufficient adhesive strength.

Furthermore, a reagent that imparts adhesive strength to this polyisobutylene or isobutylene copolymer, such as terbene resin, terbene phenol resin, rosin and modified rosin, non-reactive alkylphenol resin, aliphatic hydrocarbon resin, etc., may be added and used. Can be done.

Adhesion between a nitrile-containing resin and an olefin resin can be easily achieved by the method of the present invention, and multilayer extrusion methods such as multilayer blow molding, multilayer inflation molding, and multilayer T-die extrusion can be used to form multilayer sheets, bottles, films, etc. Molded products can be manufactured.

These molded products are particularly used for packaging foods, medicines, cosmetics, etc., and have excellent gas barrier properties, aroma retention properties, and high practical strength. Any molded product can be manufactured, including flexible molded products that require squeezability.

Examples will be described in detail below. In addition, the part in the example,
% means parts by weight, weight %. Example 1 Polypropylene was used as the outermost layer and innermost layer, a copolymer consisting of 75 parts of acrylonitrile and 25 parts of methyl acrylate was used as the core layer, and the average molecular weight was 5 × 1 as an adhesive layer for adhering these, At 200 pm, five layers of polyisobutylene having a melt viscosity of 5×1 pipoise at a die cutting speed of 12 $ec-1 were extruded.

The resin temperature was 20,000, and these were melted and bonded, extruded from a die, and the parison was blown to have an internal volume of 500.
A cc bottle was formed.

The thickness of each layer is 0.15 side, 0.015 side,
It was 0.03 sail, 0.015 side, and 0.15 rib, and its physical properties were good as shown in Table 1.

[Table] [Kono] '1' Weight increase after filling a bolt with calcium chloride and sealing it in an atmosphere of 40°C and 90% RH.

■ Using MoconOX-Tranlo automatic oxygen permeability meter (manufactured by Modem Control)
Measured in an atmosphere of q0, 0% RH.

{3} This is the peel strength between the olefin resin layer and the nitrile-containing resin layer on the outside of the bottle body, and was measured at a cross-bed speed of 20 mm/min at 50% RH.

Comparative Examples 1 to 2 The nitrile-containing resin (Comparative Example 1) and polypropylene (Comparative Example 2) used in Example 1 were each used in Example 1.
A bottle having the same shape as the above but with a body thickness of 0.4 was molded.

These bottles were designated as Comparative Example 1 and Comparative Example 2, respectively, and Example 1
The physical properties were measured under the same conditions as shown in Table 1. Example 2 Three bases of acrylonitrile and 2 $ parts of methyl acrylate were graft-polymerized to a rubber with an average particle diameter of 0.2 mm consisting of 30 parts of butadiene, 17.5 parts of ethyl methacrylate, and 2.5 parts of styrene. A nitrile-containing resin was prepared by mixing 2 parts of a graft copolymer, 6 parts of acrylonitrile, and 8 parts of a random copolymer obtained by polymerizing 2 parts of ethyl acrylate, and the other parts were the same as in Example 1. The results shown in Table 1 were obtained.

Example 3 A nitrile-containing resin obtained by latex mixing the nitrile-containing resin 8 base part of Example 1 and the graft copolymer 2 anchor part of Example 2 was used, and the other conditions were carried out in the same machine as in Example 1. Table 1 The results shown are obtained.

Example 4 A copolymer of 75 parts of acrylonitrile and 25 parts of styrene was used in place of the nitrile-containing resin of Example 1, and only this was fed into the die at 210 qo, and the rest was carried out in the same manner as in Example 1. The results shown in 1 were obtained.

Examples 5 to 9 The same procedures as in Example 1 were carried out except that the olefin resin shown in Table 2 was used, the nitrile-containing resin was the same as in Example 3, and the rest was the same as in Example 1.

However, the thickness of each layer is 0.15 side, 0.02 side, 0.025 side, 0.02 rib, 0.15 willow in order from the inside, and Table 1
The results shown are obtained. These bottles have squeeze properties and are highly flexible. Table 2 Combinations of olefin resins (numbers are weight scales) *ASTM
D1238 Examples 10 to 13 and Comparative Example 3 The same procedure as in Example 3 was carried out except that the polyisobutylene and isobutylene copolymers shown in Table 3 were used, and the results shown in Table 1 were obtained.

Table 3 Combinations of adhesive resins
14-18 Adhesives The same procedure as in Example 3 was carried out except that the extrusion amount of the adhesive resin and the thickness of the adhesive layer were changed, and the results shown in Table 4 were obtained.

Table 4: Thickness of Adhesive Resin Layer The thickness of the adhesive resin layer may be 5 mm in order to have a practical peel strength, but preferably 10 mm or more.

Claims (1)

[Claims] 1. The average molecular weight between the nitrile-containing resin layer and the olefinic resin layer is 2.0 according to the Schutaudinger viscosity formula.
1. A method for producing a barrier multilayer molded article, which comprises co-melt extruding a polyisobutylene or isobutylene copolymer layer of x10^4 to 1.0 x 10^5.