JPH0788452B2 - Resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention improves the deterioration of various performances presumed to be due to poor mixing and dispersibility in a composition of ethylene-vinyl alcohol copolymer and olefin resin. By doing
An object of the present invention is to provide a resin composition extremely useful in various packaging material fields.

B. Conventional technology Conventionally, ethylene-vinyl alcohol copolymer (EVOH)
Various technologies have been proposed for the use of a blend of olefin resin and olefin resin by making use of the excellent performance of both. For example, blending EVOH to improve or adjust the gas permeation resistance of the olefin resin, or blend EVOH to improve the heat retention of the olefin polymer film, or flexible to EVOH, Blending olefin resin to impart impact resistance, blending EVOH to improve solvent resistance of olefin resin, or blending olefin resin to improve various moldability of EVOH. Have been proposed.

However, EVOH and olefin resin originally have low affinity,
Probably because of poor dispersibility in the blended product of both, the molded product and film made of the blended product of both are remarkably impaired in certain mechanical performance, or the transparency is greatly lowered, and a satisfactory packaging material or the like cannot be provided.

C. Problems to be Solved by the Invention The present invention has the above-mentioned drawbacks, that is, in a blend of EVOH and an olefin resin, without significantly impairing some mechanical performance and without significantly reducing transparency, It is intended to provide a resin composition that can be utilized as a useful packaging material and the like by making the best use of the performance of both.

D. Means for Solving the Problems As a result of intensive studies by the present inventors, in a blend of EVOH and an olefin resin, an RS group at the terminal (where R is a hydrocarbon having 2 to 30 carbon atoms, S Is a sulfur atom) having an ethylene-vinyl alcohol-based copolymer (REVOH) or a mixture of the copolymer and EVOH, which is presumed to be based on poor mixing dispersibility of EVOH and olefin resin. It has been found that the drawbacks of are improved.

E. More Detailed Description of the Invention As described above, the REVOH of the present invention has a terminal RS group (provided that R
Is an ethylene-vinyl alcohol copolymer having a hydrocarbon having 4 to 30 carbon atoms, S is a sulfur atom), and specific examples of R are i-butyl, t-butyl, n-hexyl, n- Octyl, n-decyl, n-dothesyl, n-tetradecyl, n-hexadecyl, n-octadecyl, n
-Icosyl and the like. Of these, those having 6 to 18 carbon atoms are particularly preferably used.

REVOH is generally manufactured by the following method. That is, when performing radical copolymerization of ethylene, vinyl acetate, and optionally a small amount of other olefinic unsaturated compound, the mercaptan represented by R-SH is present, and the RS group is terminated by a so-called chain transfer method ( It can be produced by producing an ethylene-vinyl acetate copolymer introduced at one end) and saponifying it by a conventional method. The content of RS groups in all terminals of REVOH thus obtained is 30
It is at least mol%, preferably at least 40 mol%. In this case, one RS group is considered to be one monomer of the polymer component regardless of whether the terminal RS group is R or not.

The ethylene content of REVOH and EVOH mixed with it is 20 to 60 mol%, preferably 25 to 55 mol%, and the saponification degree of the vinyl acetate component is preferably 90 mol% or more. When the ethylene content is less than 20 mol%, the moldability deteriorates. When the ethylene content exceeds 60 mol%, and when the saponification degree is less than 90 mol%, the EVOH's original characteristics of gas permeation resistance and oil resistance. Properties, solvent resistance, heat retention and the like are deteriorated, which is not preferable.

From the manufacturing method of REVOH, it is inevitable that the degree of polymerization will decrease, but if REVOH having a low degree of polymerization is blended and the required performance is satisfied, blending of REVOH alone is sufficient. However, if the required performance is not satisfied even if only REVOH having a low degree of polymerization is blended with the olefin resin, for example, if it is desired to impart better impact strength, then EVV with a high degree of polymerization is added to REVOH to prevent this. It is desirable to use a mixture. In this case, the ethylene content and saponification degree of both can be arbitrarily selected within the above range, but the ethylene content and the saponification degree are preferably close to each other, for example, the difference in ethylene content is 20 mol%. Below, the difference in saponification degree is 5
It is preferably not more than mol%. REVOH melt index (MI) g / 10 minutes (measured at 190 ° C under a load of 2160 g)
Is selected from the range of 0.1 to 500, and MI of EVOH is 0.1 to 50.
Selected from the range.

The mixing ratio of EVOH to REVOH can be arbitrarily selected depending on the application, and surprisingly, EVOH has a mixing ratio of only 5 to 5.
Only by including 10% of REVOH, it is possible to prevent the performance deterioration estimated to be based on the poor dispersibility with the olefin resin. In this case, olefin resin and REVOH are mixed and dispersed beforehand,
The method of blending this composition with EVOH can be extremely effective.

The olefin resin (B) to be blended with REVOH or a mixture of REVOH and EVOH (B) can be arbitrarily selected according to its application, and examples thereof include low density, medium density, high density polyethylene, polypropylene, ethylene- Examples thereof include a propylene copolymer, a propylene-butene-1 copolymer, an ethylene-vinyl acetate copolymer, an ion-crosslinked olefin copolymer, or a mixture of two or more of these.
The mixing ratio of (A) and (B) is appropriately determined depending on the application, and can be arbitrarily selected within the range of 95: 5 to 5:95 by weight ratio. For example, for the purpose of improving the gas permeation resistance and solvent resistance of a polyethylene container,
(A): (B) is mainly used within the range of 5:95 to 45:55, and for the purpose of imparting impact resistance and flexibility to EVOH, (A): (B) is 55: Mainly used in the range of 45 to 95: 5. As the blending method, known methods such as a Banbury mixer method and a melt blending method using a single-screw or twin-screw extruder can be adopted. Further, in the case of this blending, other additives such as an antioxidant, an ultraviolet absorber, a lubricant, within a range that does not impair the action and effect of the present invention,
A plasticizer, an antistatic agent, a coloring agent and the like can be added.

The resin composition of the present invention thus obtained can be easily molded by a well-known melt molding method, and can be molded into an arbitrary molded product such as a film, a sheet, a tube or a bottle. It is also used as a multi-layer laminate with other thermoplastic resins such as polyethylene, polypropylene, polyethylene terephthalate, polyamide, polystyrene, etc., and is formed by a known method such as multi-layer coextrusion, co-injection, extrusion coating, and various packaging materials. Used for etc. As the multilayer laminate, when the resin composition of the present invention is E and the thermoplastic resin is P, P / E, P / E / P, P / E / P / E / P, E / P / E, E / P /
The layer structure such as E / P can be mentioned. In this case, an interlayer adhesive may be provided between the layers, if necessary.

Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to these examples.

F. Examples Example 1, Control Example 1 Ethylene-vinyl alcohol of melt index 10 having an ethylene content of 29 mol% and a saponification degree of 99 mol% and having n-dodecylthiyl group at 45 mol% of one end thereof. After mixing 20 parts by weight and 80 parts by weight of low-density polyethylene (density 0.921, melt index 1.5), the mixture is supplied to an extruder having a uniaxial full flight type screw, pelletized at a temperature of 220 ° C., and then the pellet is T- The film was supplied to an extrusion film-forming machine equipped with a die to produce a film having a thickness of 40 μm under the following conditions.

Extruder: 40mm diameter screw: Full flight type, L / D = 28, compression ratio 4.0 dy: T-die 300mm width Film forming temperature: Cylinder, 180 ℃, 210 ℃, 220 ℃ die, 220 ℃ Collection speed: As a control example, ethylene-vinyl alcohol having an ethylene content of 29 mol%, a saponification degree of 99 mol% and a normal end of melt index 10 was used, and a mixing operation with polyethylene was performed in the same manner as above. A 40 μ film of the resin composition was obtained. Table 1 shows the results of measuring the main physical properties of both films. Significant differences were observed in terms of tensile strength at break and elongation and transparency.

Examples 2 to 5 and Control Examples 2 to 5 Using REVOH used in Example 1, films of compositions with various olefin resins were produced in the same manner as in Example 1.
As a control, EVOH used in Comparative Example 1 was used to obtain a film of a composition with various olefin resins, and Example 1 was used.
Similarly, the physical properties were compared. The results are shown in Table 2.

Example 6, Control Example 6 20 parts by weight of ethylene-vinyl alcohol in a melt index 65 having an ethylene content of 34 mol% and a saponification degree of 97 mol% and having an n-octadecylthiyl group at 86 mol% of one end thereof. And 28 parts by weight of vinyl acetate and 80 parts by weight of an ethylene-vinyl acetate copolymer are mixed and pelletized in advance. Next, ethylene content 34 mol%, saponification degree 99 mol%,
30 parts by weight of the above mixed pellets were mixed with 70 parts by weight of ethylene-vinyl alcohol pellets having a melt index of 2.6 and having a normal end, and a film having a thickness of 60 .mu.m was obtained using the same apparatus as in Example 1.

As a control, 76 parts by weight of the above-mentioned usual ethylene-vinyl alcohol pellets were mixed with 24 parts by weight of the above ethylene-vinyl acetate copolymer pellets to obtain a film having a thickness of 60 .mu.m.

As a result of measuring the physical properties of both films, significant differences in impact strength and haze were observed. The results are shown in Table 3.

Examples 7 to 8 In Example 6, the type of REVOH was changed, and the other operations were the same, to obtain a film having a thickness of 60 μm. These physical properties were measured as in Example 6. The results are shown in Table 4.

G. Action and effect REVOH or a mixture of REVOH and EVOH according to the present invention, a film, a sheet, a container, etc. using a composition of an olefin resin are significantly more than those of a conventional composition of EVOH and an olefin resin. It has excellent mechanical performance and transparency, and is widely and suitably used in various packaging material fields.

Claims (2)

[Claims] 1. An ethylene-vinyl alcohol-based copolymer having an RS group at the terminal (wherein R is a hydrocarbon having 4 to 30 carbon atoms, S is a sulfur atom), or an RS group at the terminal with the copolymer. A resin composition comprising an ethylene-vinyl alcohol copolymer mixture (A) and an olefin resin (B), and the weight ratio of (A) to (B) is 95: 5 to 5:95. 2. (A) is an ethylene-containing terminal RS group
The mixture of a vinyl alcohol copolymer and an ethylene-vinyl alcohol copolymer having no RS group at the terminal, the weight ratio of which is 95: 5 to 5:95. Resin composition.