JPH04122756A - Ethylene-vinyl copolymer composition - Google Patents

Abstract

PURPOSE:To prepare the title compsn. improved in flexibility, fabricability, molded appearance, etc., by compounding an ethylene-vinyl alcohol copolymer with an olefin copolymer modified with a vinylsilane compd. to give a compsn. having a specified acid content, etc. CONSTITUTION:An ethylene-vinyl alcohol copolymer contg. 20-65mol% ethylene is compounded with an olefin copolymer modified with 0.005-5mol% vinylsilane compd. in a wt. ratio of the former to the latter copolymer of (5:95) to (95:5), giving the title compsn. having a Ca and/or an Na content (Met) satisfying formula I and an acid content (HAc) satisfying formula II.

Description

DETAILED DESCRIPTION OF THE INVENTION A-1 The present invention relates to a resin composition in the field of food packaging that significantly improves the moldability during packaging, the appearance quality after packaging, and has high gas barrier properties.

Ethylene-vinyl alcohol copolymer (EVOH) is
It is recognized for its high gas barrier properties and is widely used in the food packaging field, etc. Due to its crystallinity, it has poor flexibility and is used in food packaging (secondary packaging). Z-zushi is also not satisfactory in terms of suitability (processing), appearance quality after packaging, performance (drop strength, pinhole resistance, etc.), and as a result, it has poor reliability, such as variations in gas barrier properties. Stay where improvements are desired.

To solve these problems, EVOH is made of ethylene-vinyl acetate copolymer (EVA) and polyamide (PA).
), attempts have been made to blend various nilastomers, and a method in which a vinylsilane-modified polyolefin is blended (Japanese Patent Application Laid-open No. 15541-1983)
2) In either case, the current situation is whether the product satisfies all of the above-mentioned suitability for secondary processing, appearance quality after packaging, and performance.

In other words, by blending EV OH with EV, AS, or maleic anhydride EVA, is there any improvement in flexibility, appearance quality (decrease in transparency), and suitability for secondary processing compared to EVOH compounds? (Whitening during stretching, occurrence of vinyl poles)
There are problems in terms of

The E V OH composition, which is made by bulleting PA into EVO)l, has a good appearance quality and a small improvement effect on flexibility.
When recycled and used, coloring and gels are likely to occur.

However, when EVOH is pelleted with vinylsilane-modified polyolefin, the effect of improving the flexibility of the EVOH composition is either slightly observed or not necessarily sufficient, and worse, when blended or recycled, it causes discoloration and There is a problem that gels are likely to occur.

Problems to be solved by C and R The present invention provides flexibility to EV OH, suitability for secondary processing, appearance quality, and performance (drop strength, pinhole resistance, etc.)
and high gas barrier property E that greatly improves recovery and usability.
An object of the present invention is to provide a VOH resin composition.

D Solving the Problem 7': Island 1 The present inventors have created an EVOH composition in which E V A (A) is blended with various thermoplastic resins in a saponified solution, or EVOH is blended with various thermoplastic resins in a saponified manner. Did E
The V OH composition was formed into a film, and the flexibility (normal temperature and high iA
) and appearance (gel, bubble, snow and transparency).
My rating is 1.

First, various thermoplastic resins such as polyvinyl acetate (PVAc), ionomer (10
) etc. were blended and saponified in solution to form a film of 7:EνOH composition. As a result, the flexibility at room temperature (20'C) was relatively good, but the transparency and appearance of the film were poor.

First, we evaluated film formation by blending EVOH with modified polyethylene containing a vinylmethoquinonolane compound.

So, as a result of a rough study, the present inventors surprisingly found that a vinyl 7-run modified olefin copolymer (B) was blended with EV A (A') under solution and saponified.
: When the EV OH composition (C) was formed into a film, the flexibility was good, and in some cases, a film was obtained that was transparent with few bumps and had a good appearance. Furthermore, as a result of intensive studies, it was discovered that when the EVOH composition satisfies the following (1) to (U), a film with a very good appearance can be obtained,
f2 to complete the present invention.

5≦Met≦500 (
I) 10≦HAc≦1000
(II) Calcium and/or Met in the composition contain sodium! (ppm) The acid component content (ppm) in the HAc composition and the vinyl silane-modified polyolefin (B
) is blended under melting conditions. When EVA (A') and resin (B) before saponification are solution-blended and saponified, the EVOH composition is prepared by blending the
3). The groups preferentially react with the -〇H group of EVA (Ao) generated in the saponification reaction without self-condensation, thickening, or gelation! A gel-free composition with good temple transparency and flexibility is obtained. This is also clear from the examples described below.

The present invention will be further described in detail below.

In the present invention, EVA (A') is an ethylene-vinyl acetate copolymer, and the ethylene content is 20 to 65
mol %, preferably 25 to 58 mol %. If the ethylene content is less than 1120 mol %, the EV○H composition after saponification will have poor melt moldability, while if it exceeds 65 mol %, the gas barrier properties of the saponified EV OH composition will be insufficient.

One of the more preferable requirements is that the EVA(,'l') or the vinylane compound is 0005 to 05 mol%, preferably 0.
EVA (,4'
) to use L). By using such EvA(A'), the improvement effect becomes more noticeable.

Second, the EVOH (A), EV A (A') may be used with other monomers, such as propylene, butylene, unsaturated carboxylic acid or ester thereof ((meth) ) acrylic acid, (meth)acrylic ester (methyl, ethyl)), vinylpyrrolidone (
(N-vinyl-2-pyrrolidone, etc.) may be copolymerized with the following (X), (Y) and (2). The compounds shown are preferred.

HRffi CH2=C(CHI), Si R'+31+
Pa・(X)R3F! 'R6゜CHz"CC-\-R' SI R'+3-ml
... ()“)R3R8yuCH, = C-Si-(○c R9) (3-m)
... (Z) [where n is 0 to 1,
m is 0 to 2, R1 is a lower alkyl group, an allyl group, or a lower alkyl group having an allyl group, R2 is a carbon number of 1 to 4
0, and any oxygen-containing substituent may be added to the alkokynol group. R3 is hydrogen, R4 is a hydrogen atom or a lower alkyl group, R5 is an alkyl group, and f2 is a chain carbon atom or oxygen. residue, R6 is hydrogen, halogen, lower alkyl group, allyl group, f2 is a lower alkyl group having an allyl group, R7 is an alkokyl group or an anoquinol group (here, an alkokyl group or an anoquinol group) may have a substituent containing oxygen or nitrogen). ), R8 is hydrogen,
A halogen, a lower alkyl group, an allyl group, or a lower alkyl group having an allyl group, R9 is a lower alkyl group. ] More specifically, R1 is a lower alkyl group having 1 to 5 carbon atoms, an allyl group having 6 to 18 carbon atoms, or a lower alkyl group having 1 to 5 carbon atoms having an allyl group having 6 to 18 carbon atoms; R4 represents a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, and R5 represents an alkyl group having 1 to 5 carbon atoms, or a chain carbon atom or a divalent organic residue bonded to each other for oxygen or nitrogen. and R6 is hydrogen, halogen, a lower alkyl group having 1 to 5 carbon atoms, an allyl group having 6 to 18 carbon atoms, or a C 1 having an allyl group having 6 to 18 carbon atoms.
~5 lower alkyl group, R7 is an alkokynol group or anloquinol group (herein, the alkokynol group or anoloquinl group may have a substituent containing oxygen or nitrogen), R8 is hydrogen, halogen , carbon number 1~
R9 represents a lower alkyl group having 1 to 5 carbon atoms, an allyl group having 6 to 18 carbon atoms, or a lower alkyl group having 1 to 5 carbon atoms having an allyl group having 6 to 18 carbon atoms, and R9 represents a lower alkyl group having 1 to 5 carbon atoms. show. Vinylsilane compounds (X), (Y), (2
) Specific examples of the compound f2 include vinyltrimethoxysilane, vinyltriethquinolane, vinylmethylnomethquinsilane, and γ-methacryloquinobrobylmethquinonolano. Among them, vinyltrimethoxysilane and vinyltriethoxysilane are preferably used.

Next, the vinylsilane-modified olefin copolymer (B) will be described. The resin (B) used in the present invention is an L-olefin copolymer obtained by copolymerizing a vinyl silane compound and making a similar craft. More specifically, the formula (X),
It is a nolan-modified olefin copolymer modified with vinylsilane represented by (Y), (Z), etc. More specifically, examples include vinyltrimethoquinonolane, vinyltriethoquinonolane, and vinyltriasecoquino-7rane. It is also possible to blend an unmodified olefin copolymer (which may be the same or different from the 7-run modified olefin copolymer) with the nolano-modified olefin copolymer.

A method for obtaining the vinylanolan-modified olefinic copolymer (B) by copolymerization is disclosed in JP-A-55-9611, etc. /am'
Copolymerization is carried out at a temperature of 100 to 400°C using a radical polymerization initiator and, if necessary, in the presence of a chain transfer agent. In this case, a third monomer such as vinyl acetate, acrylic acid, methacrylic acid, and their esters may be copolymerized.

On the other hand, as a method for introducing a noryl group by grafting, there is a method disclosed in JP-A-4L-1711. For example, the vinyl 7 run compound and radical generator are fed to an olefin copolymer into an extruder, and 180
This is a method of extrusion at a Norinoder temperature of ~240°C. In this case, the Rancar generator is dicumyl peroxide,
Suitable examples include organic peroxides such as benzoyl peroxide.

The content of the vinylsilane compound in the copolymerized or grafted 1-niolefin copolymer is 0.0005 to 5 mol%, preferably 0.01 to 4 mol%, more preferably 0.01 to 5 mol%.
It is 2 mol%. The content of vinyl silane compounds is 0.
If the amount is less than 0.005 mol %, a product with good transparency cannot be obtained, while if it is more than 5 mol %, gels and bumps may occur frequently during film formation.

As the olefin copolymer which is the base material of the olefin-modified olefin copolymer (B), the olefin is 67 to 10
Those containing 0 mol% are preferably used, specifically polyethylene and polypropylene, especially those containing 3% to ethylene.
9 mol% or less, preferably 3 to 39 mol% propylene,
A resin obtained by copolymerizing at least one of vinyl acetate, acrylic acid, methacrylic acid, and esters thereof is suitable. Among these, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid ester (methyl ester, ethyl ester) copolymer are more suitable.

By the way, in the present invention, the blending method of E, VA (A-) and the vinylsilane-modified olefin copolymer (B) is important. Solvents in which both are uniformly dissolved at the temperature of used. (A
) solution and (B) solution, or (A) and (B)
) is mixed in a stirrer, static mixer, twin-screw kneading extruder, or bubbling in a distillation column tray. It is. EVA(A'
) and the vinylanlan-modified olefin copolymer (B), the weight ratio is (A')/(B) or 5.
/95-9515, preferably 30/70-94/6,
More preferably, it is 50/50 to 93/7. (A'
)/(B) is less than 5/95, EVOH after saponification
The gas barrier properties of the composition are insufficient, and on the other hand, if it exceeds 9515, the effect of improving flexibility will be insufficient.

Furthermore, after saponifying EVA (A'), E V OH (
The blend ratio of A) and (B) is the ratio of the weight of EVOH reduced by saponification to the weight of (B).

The above mixed solution is mixed with an acid (e.g. sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid) or an alkali (e.g. caustic soda, caustic potash, lithium hydroxide, etc.) catalyst against the resin.
001 to 5 mol% is added and saponified at a temperature of 60 to 200°C. At this time, it is important to limit the amount of catalyst added in order to prevent coloring of the resin, and for this purpose it is important to remove by-products generated during saponification, such as methyl acetate, from the reaction system as quickly as possible. . Furthermore, in order to avoid precipitation of the above-mentioned raw materials or their saponified products during the reaction, it is important to keep the reaction temperature as high as possible.

The average saponification degree of the vinyl acetate component in the composition obtained by saponifying the mixed solution is 90% or more, preferably 95% or more, and more preferably 97% or more. Saponification degree is 90%
If it is less than that, gas barrier properties and thermal stability will deteriorate.

The solution of the saponified composition is solidified by cooling as it is or by replacing the solvent with water, etc., and then draining it into alcohol-water, acetic acid-water, distilled water, or water to remove impurities such as the solvent, catalyst, and oligomer contained therein. and further, the above formula (
Sodium and 7/ to satisfy I) to (II)
Or immersed in a solution containing calcium metal salt and acid, then dehydrated and dried at 60 to 150°C,
The composition is obtained.

The composition is used as it is or after being made into a melt pellet.

By the way, M e t of the above formulas (I) and (II) is 5pp
If II is less than 1, and/ma f2 is HA c is 1
When it is more than 1000 pp, not only the transparency of the film deteriorates, but also the appearance of gels, blurs, and streaks increases. On the other hand, N
et or more than 500ppm and/or HAc is 10p
If it is less than pm, not only the transparency deteriorates but also the film becomes too colored to be usable. Therefore, the formula (1
) and (II) must be satisfied at the same time, preferably 10≦Met≦400.20≦HAc≦800,
More preferably 20≦Net≦3 (1350≦HAc≦5
It is 00.

Met is a compound of sodium compounds present in EVOH compounds, sodium and/or calcium in calcium compounds, and two iron compounds such as sodium phosphate, sodium acetate, sodium carbonate, and caustic soda. I can give you strength. Calcium compounds include calcium chloride, calcium phosphate,
Calcium acetate and calcium hydroxide are often mentioned.

M is the content of acid present in the E V OH composition, where the acid can be an inorganic acid or an organic acid, preferably acetic acid.

The composition includes, to the extent that the purpose of the present invention is not hindered,
Plasticizers, heat stabilizers, ultraviolet absorbers, antioxidants, colorants, fillers, and other resins (polyamide, partially humanized ethylene-vinyl acetate copolymer, etc.) may be blended freely.

Also, a suitable melt index (MT) of the composition
(190℃, under 2160g load) is 01~50g/1
0 m1n, optimally 0.5-20 g/10 m1n.

In the present invention, the EVOH composition (C) can be used as a single layer, or it is usually used in a multilayer structure such as a polyolefin resin layer or a Norland layer.

Therefore, for multi-layering, the adhesive resin used is one that firmly adheres to the EVOH composition (C) layer, polyolefin resin, or Norland layer.
Although not particularly limited, unsaturated carboxylic acids or their anhydrides (such as maleic anhydride) can be used in olefinic polymers or copolymers [polyethylene f low density polyethylene (LDPE), linear low density polyethylene ( LLDPE
), very low density polyethylene (SLDPE)), ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid ester (methyl ester) copolymer].

Methods for obtaining a multilayer structure, such as a multilayer film, include extrusion lamination, dry lamination, coextrusion lamination of the EVOH composition (C), a polyolefin resin, a wetted resin, etc. via an adhesive resin,
Examples include methods for obtaining a laminate by a coextrusion notebook molding method, a coextrusion vibe molding method, a co-injection molding method, a solution coating method, and the like.

There are no particular limitations on the method for collecting and reusing scraps such as trim and defective containers generated during molding.

A method in which the scrap is pulverized, dried if it has absorbed moisture, and then triblended with a raw material polyolefin resin; a method in which the pulverized scrap is made into pellets and then triblended with a raw material resin; There is a method of making a blend pellet from the above. The blending ratio of raw resin and scrap is not particularly limited either, and is usually blended at a ratio of about 2 to 80%. At this time, maleic anhydride-modified polyolefins, maleic anhydride-modified polyolefin-polystyrene copolymers, etc. ,
It may be preferable to add one or more metal soaps, hydrotalcite compounds, etc.

Furthermore, there are no particular limitations regarding the thickness structure of the multilayer film.When considering moldability, cost, etc., the total layer thickness is usually 10 to 5000μ,
It is preferably 15 to 2000μ, and the EV for the total thickness is
The thickness ratio of the OH composition (C) layer is 1 to 40%, more preferably 2 to 30%. 12) The structure of the multilayer film is EV OH (C) layer/adhesive resin layer/polyolefin resin layer, polyolefin resin layer/adhesive resin layer/EV OH (C) layer/adhesive resin layer/ Polyolefin resin layer, EVOH (C) layer/adhesive resin layer 7 layer collection, EVOH (C) layer/adhesive resin layer 7 layer collection/polyolefin resin layer, polyolefin resin layer 7 layer collection/adhesiveness Resin layer / EV○H (C) layer / Adhesive resin layer / Polyolefin resin layer, polyolefin resin layer 7 collection / Adhesive resin layer / EV OH (C) layer / Adhesive resin layer 7 collection / Polyolefin resin layer, recovery layer/adhesive resin layer/
Typical examples include EV OH (C) layer/adhesive resin layer/polyolefin resin layer, recovery layer/adhesive resin layer/EV OH (C) layer/adhesive resin layer, etc. When providing polyolefin resin layers on both outer layers,
The resins may be different or the same. Generally, a Norland layer is provided on one side (the innermost layer is the outermost layer) or both sides (the innermost layer and the outermost layer) of the multilayer body, either directly or via an adhesive resin layer.

The present invention will be explained in detail below using Examples, but the present invention is not limited thereto.

Knee IL disturbance Example 1 EVA (A')80 with 1144 mol% ethylene content and 0012 mol% vinyltrimethoxy7-norane content
parts by weight and 20 parts by weight of a nolan-modified ethylene-vinyl acetate copolymer (B) containing 70 mol% of ethylene and 0.55 mol% of vinyl methquine 7 run were dissolved in methyl sulfokind under heating (concentration: 20% by weight). ), the two were mixed and sufficiently homogenized with a stirrer, and then 120 g of 10 parts of a methanol solution of Q concentration was added dropwise under pressure and stirring at 150°C, and the by-product (acetic acid) was removed using methanol vapor. methyl, etc.).

After 1 hour, the solution was cooled to 60°C, and after 1 hour, it was poured into cold water with stirring, and the EVOH composition (C) was added. The composition was thoroughly washed with a large amount of acetic acid water having an Ig/Q concentration, and then further washed with distilled water.

Next, 0.1g/r2-noacetic acid and 0.07g/1IC
I) Sodium acetate and 0.04 g of acetic acid were dissolved and the composition was immersed in an aqueous solution for 4 hours, then the liquid was removed and dried in a hot air dryer at 110°C for 24 hours.

At this time, the Ml of the EVOH composition at 190°C and under a load of 2160 g was 1.5 g/10 m1n, (A),
The degree of saponification of the vinyl acetate component in (B) is 98.8%, and the composition contains Ca'- and Na! (Met) is 58ppm
, and the acid (acetic acid) component content (HAc) in the composition is 9
It's 0ppm.

The EV OH composition (C) was passed through a 40φ extruder, N, bottom,
The composition (C) was pelletized at 180°C, dried under reduced pressure at 50°C for 16 hours, and then the composition (C) was coated with ethylene-vinyl acetate copolymer (EVA) (Evaflex EV manufactured by Mitsui Polychemical Co., Ltd.) as the Norland layer. 460) and a maleic anhydride-modified ethylene-vinyl acetate copolymer (Atomer VF600 manufactured by Mitsui Petrochemicals) as the adhesive resin, a composition (C)/adhesive resin/
A multilayer film of Norland configuration was obtained. The thickness of the film at this time was set at 5/IO/35μ, respectively.

To measure the properties of the film, a film with a width of 15 mm and a length of 1
It was cut into 0 cm pieces and tested at 20°C and 120°C using a tensile testing machine with a constant temperature shaker (AG-500A manufactured by Shimadzu Corporation).
So, the chuck interval is 50n+m, and the pulling speed is 100mm/m.
Tensile strength and elongation were measured at in. Mafoko, 20°C
- To measure oxygen gas barrier properties under 60% RH (measuring device manufactured by Mocon). The results are shown in Table 1.

Examples 2 to 5, Comparative Examples 1 to 8 The same conditions as in Example 1 were used except as shown in Table 1. The results are shown in Table 1.

Margin F below Effects of the Invention The present invention has excellent flexibility and has greatly improved appearance.
This is a high-casbarrier EVOH composition.

Claims (1)

Scope of Claims: (1) An olefin modified with an ethylene-vinyl alcohol copolymer (A) having an ethylene content of 20 to 65 mol% and a vinyl silane compound and having a content of 0.005 to 5 mol%. An ethylene-vinyl alcohol copolymer composition comprising a copolymer (B) and satisfying the following formulas (I) to (II). 5≦Met≦500 (I) 10≦HAc≦1000 (II) However, Met: content of calcium and/or sodium in the composition (ppm) HAc: content of acid components in the composition (ppm) (2 )(A
2. The ethylene-vinyl alcohol copolymer composition according to claim 1, wherein said ethylene-vinyl alcohol copolymer is an ethylene-vinyl alcohol copolymer modified with a vinylsilane compound and whose content is 0.0005 to 0.5 mol%. (3) An ethylene-vinyl acetate copolymer (A') having an ethylene content of 20 to 65 mol%, modified with 5 to 95% by weight and a vinyl silane compound, and having a content of 0.005 to 65% by weight.
5 mol% olefin copolymer (B) 5-95% by weight
2. An ethylene-vinyl alcohol copolymer composition obtained by saponifying a mixed solution of
An ethylene-vinyl alcohol copolymer composition that satisfies I) to (II). (4) The ethylene-vinyl alcohol copolymer according to claim 3, wherein (A) is an ethylene-vinyl acetate copolymer modified with a vinylsilane compound and having a content of 0.0005 to 0.5 mol%. Coalescing composition.