JP2003520284A - Composition based on ethylene-vinyl alcohol copolymer and polypropylene - Google Patents

Abstract

  (57) [Summary] PROBLEM TO BE SOLVED: To provide a composition based on an ethylene-vinyl alcohol copolymer and polypropylene having a barrier property against gas, especially oxygen gas. Useful as packaging material. A composition comprising (1) 55 to 99.5 parts by weight of an EVOH copolymer, and (2) 0.5 to 45 parts by weight of a polypropylene (A) and a compatibilizer (B), wherein (A) The ratio (A) / (B) of (B) is 1 to 5, and the ratio of EVOH MFI to polypropylene MFI (melt flow index) is 5 or more.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION

The present invention relates to a composition based on ethylene-vinyl alcohol copolymer (EVOH) and polypropylene.

[0002]

[Prior art]

EVOH copolymers have barrier properties to many gases, especially oxygen gas. Many food packaging materials have a layer of EVOH film. Compositions based on EVOH and polyolefins with a high proportion of EVOH have excellent barrier properties. The compositions of the present invention are used to make barrier films for food packaging materials.

EVOB copolymers generally have various excellent properties such as oxygen impermeability, mechanical strength,
It has other properties and has many uses as they are, such as films, sheets, raw materials for containers, fibers and the like. However, this copolymer has the disadvantage of varying the product thickness during the film or sheet forming process, thus reducing the commercial viability of the product. Furthermore, due to lack of stretchability and flexibility, deep drawing in drawing process or non-uniform elasticity when drawing process will cause pinholes during use of the product, greatly limiting its use as a packaging material. To be done. By adding the polyolefin to EVOH, the resulting mixture has better flexibility and better moldability. However, 20% or more cannot be added to maintain the barrier.

The oxygen barrier properties of EVOH copolymers decrease significantly with increasing relative humidity (RH). In contrast, the mixture of EVOH and polyolefin is not sensitive to relative humidity. This is another reason for adding polyolefins to EVOH. Another reason to add polyolefins to EVOH is that polyolefins are generally less expensive than EVOH.

European Patent EP 418 129 describes a mixture based on EVOH with 9.5 to 14.25% polypropylene and 5% compatibilizer. This mixture can be easily molded and the resulting film is used as a packaging material. EP 441 662 also discloses the same mixture, but the film obtained from this mixture is more resistant to hot water and steam than the pure EVOH film, and therefore the packaging material containing this film is Has excellent resistance to sterilization. This effect is important in the case of food packaging materials. In the above two patents, the ratio of EVOH MFI to polypropylene MFI is equal to 3 (M
FI is measured at 230 ° C and under a load of 2.16kg). The applicant of this patent tried to increase the proportion of polypropylene in the mixture, but then could not be formed into a film.

European Patent EP 440 559 discloses a mixture of EVOH, a polyolefin and a compatibilizer. Comparative Example 4 shows a mixture (weight ratio) of 60% EVOH, 35% polypropylene and 55% compatibilizer. The ratio of the amount of polypropylene to compatibilizer in this case is equal to 7. The resulting film has no oxygen barrier. European Patent EP 444 977 also discloses mixtures of EVOH, polyolefins and compatibilizers. Comparative Example 4 shows a mixture (weight ratio) of 55% EVOH, 20% polypropylene and 25% compatibilizer. That is, the ratio of the amount of polypropylene to compatibilizer is equal to 0.8. The resulting film has no oxygen barrier. Moreover, the ratio of MOH of EVOH to MFI of polypropylene in this mixture is 0.29.

The present inventor selects the ratio of polypropylene such that the ratio of MFI of EVOH to MFI of polypropylene is 5 or more, and the ratio of the amount of polypropylene to the compatibilizer is 1 to 5. It was discovered that by choosing the ratio of compatibilizers, a mixture of EVOH, polypropylene and compatibilizer up to 45% polypropylene was obtained. This mixture can be easily molded and has an excellent oxygen barrier property. Other effects are shown below.

[0008]

[Problems to be Solved by the Invention]

It is an object of the present invention to provide an EVOR-based composition containing as much polypropylene as possible while retaining the barrier.

[0009]

[Means for Solving the Problems]

The present invention provides a composition comprising (1) 55 to 99.5 parts by weight of an EVOH copolymer, and (2) 0.5 to 45 parts by weight of a polypropylene (A) and a compatibilizer (B). (B)
The ratio (A) / (B) of 1 to 5 is 1 to 5, and the ratio of MFI of EVOH to MFI (melt flow index) of polypropylene is 5 or more.

[0010]

Embodiments

EVON copolymers are also called saponified ethylene-vinyl acetate copolymers. The saponified ethylene-vinyl acetate copolymer used in the present invention is a copolymer having an ethylene content of 20 to 60 mol%, preferably 25 to 55 mol%, and the degree of saponification of the vinyl acetate component is at least 95 mol%. If the ethylene content is less than 20 mol%, the oxygen impermeability under high humidity conditions will be lower than the required value. On the other hand, when the ethylene content exceeds 60 mol%, the oxygen impermeability is deteriorated, and the printability and other physical properties are deteriorated. The degree of saponification or hydrolysis is 95mo
Below l%, oxygen impermeability and wet strength are sacrificed. This saponified copolymer having a melt flow index of 0.5 to 100 g / 10 min is particularly useful. With the ratio of polypropylene to MFI being satisfied, MFI is 10 to 30 (g / 10 minutes, 230 ° C / 2.16kg
It is preferred to choose between).

This saponified copolymer is an α-olefin such as propylene, isobutene, α-octene, α-dodecane, α-octadecene, etc., an unsaturated carboxylic acid or a salt thereof, a partial alkyl ester, a complete alkyl ester. , Nitriles, amides, acid anhydrides of the above acids and other comonomer components including unsaturated sulfonic acids or salts thereof can be included in small proportions. The oxygen permeability of the EVOH copolymer film is measured according to ASTM D 3985 and is expressed in cm ³ of volume of oxygen passing through a thickness of 25 μm per 24 hours with a pressure difference of 1 bar. In the present specification, it is referred to as O ₂ GTR for entertaining. This O ₂ GTR changes in inverse proportion to the film thickness. O ₂ GTR in O ₂ GTR is 0.72,75% RH at 0% RH of EVOH containing 38 mol% of ethylene units
Is 3.1.

EVOH containing 29 mol% ethylene units has an O ₂ GTR of 1.41 at 75% RH and 0.1 at 0% RH. The above grades are commercially available. These grades are used in various thicknesses according to the required barrier properties (type of article to be stored, storage time, etc.). Polypropylene (A) is a homopolymer or a copolymer, and the copolymer may be a block copolymer or a random copolymer. The comonomer of the copolymer can be selected from α-olefins having up to 30 carbon atoms. Examples of α-olefins include 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl
-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decane, 1-dodecane, 1-
Tetradecane, 1-hexadecene, 1-octadecene, 1-eicocene,
Mention may be made of 1-decocene, 1-tetracocene, 1-hexacocene, 1-octacocene and 1-triacontene. These α-alpha olefins can be used alone or as a mixture of at least two. The comonomer may be a diene.

Polypropylene (A) may be blended with EPR (ethylene-polypropylene rubber or elastomer) or EPDM (ethylene-polypropylene-diene elastomer). Polypropylene (A) contains at least 50 mol% propylene, preferably 75 m
It is preferably a mixture of a plurality of polymers containing ol%. MFI of polypropylene (A) is 0.5 to 3 (g / 10 minutes, 230 ° C / 2.16kg), preferably 1 to 2
It is preferably 0.5. However, it is necessary to satisfy the condition of the above ratio of MFI to EVOH. The MFI used in the calculation of the EVOH MEl to polypropylene MFI ratio is measured under the same temperature conditions and under the same load. The measurement is preferably carried out at 230 ° C. under a load of 2.16 kg. In the preferred embodiment, this ratio is between 5 and 25, preferably between 8 and 15. twenty five
As mentioned above, values of 30 to 40 may be used, but in this case, the corresponding composition based on EVOH cannot be reproducibly obtained.

The compatibilizer (B) is also any polymer capable of dispersing polypropylene in EVOH. Examples are functionalized polyolefins, such as ethylene homopolymers or maleic anhydride grafted copolymers, propylene homopolymers or maleic anhydride grafted copolymers, maleic anhydride grafted EPR or EPDM elastomers. Can be mentioned. The compatibilizer (B) is preferably polyethylene having a polyamide graft chain or polypropylene having a polyamide graft chain.

Polyethylene having a polyamide graft chain is (i) a copolymer of ethylene (
Obtained by reaction of B1) with the grafted unsaturated monomer X or (ii) copolymerization with polyamide (B2). The copolymer (B1) can be a copolymer of ethylene and unsaturated monomer X, or a polyethylene grafted with unsaturated monomer X. X
Is any unsaturated monomer having a functional group capable of copolymerizing with ethylene, grafting to polyethylene and chemically reacting with polyamide. This functional group can be a carboxylic acid, a dicarboxylic acid anhydride, an epoxy, etc.

Examples of the monomer X include (meth) acrylic acid, maleic anhydride, unsaturated epoxides such as glycidyl (meth) acrylate, and maleic anhydride is preferably used. The polyethylene grafted with X can be a homopolymer or copolymer of polyethylene.

The comonomers may include: (1) α-olefins, preferably those having 3 to 30 carbon atoms, especially polypropylene, (2) unsaturated carboxylic acid esters such as alkyl (meth). Acrylates (alkyl carbon atoms up to 24), especially alkyl acrylates, examples of (meth) acrylates include methyl methacrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate and 2-ethylhexyl acrylate. .
(3) Vinyl esters of saturated carboxylic acids, such as vinyl acetate or vinyl propionate, (4) Dienes such as 1,4-hexadiene, (5) Polyethylene (which may contain multiple comonomers)

The polyethylene is preferably a mixture of polymers, with at least 50 mol%, preferably 75 mol% ethylene and a density of 0.86 to 0.98 g / cm ³ . MFI (19
The viscosity index at 0 ° C / 2.16 kg) is preferably 1 to 1000 g / 10 minutes. Examples of polyethylene include: 1) low density polyethylene (LDPE), 2) high density polyethylene (HDPE), 3) linear low density polyethylene (LLDPE), 4) ultra low density polyethylene (VLDPE),

5) Polyethylene obtained by metallocene catalysis, ie ethylene and α-alpha olefins such as propylene, butene, in the presence of a monosite catalyst generally consisting of zirconium or titanium atoms and two alkyl cyclic molecules bound to the metal. Polymers obtained by copolymerization with, hexene or octene. The metallocene catalyst generally consists of two metal-bonded cyclopentadiene rings.
This catalyst is generally used together with an aluminoxane as cocatalyst or activator, preferably methylaluminoxane (MAO). Hafnium to which cyclopentadiene is bonded can also be used as a metal. Other metallocene catalysts are in the periodic table
It can include Group IVA, VA and VIA transition metals. Lanthanide series metals can also be used.

6) EPR elastomer (ethylene-propylene-rubber), 7) EPDM elastomer (ethylene-propylene-diene), 8) a mixture of polyethylene and EPR or EPDM, 9) ethylene-alkyl (meth) acrylate copolymer (( (Meth) acrylate is 60% by weight or less, preferably 2 to 40% by weight).

Grafting methods are known. In the copolymer of ethylene and monomer X, that is, the copolymer of ethylene grafted with X, X and the other optional monomer can be selected from the above comonomers described for the ethylene copolymer grafted with X. Preferably, ethylene-maleic anhydride, ethylene-alkyl (meth) acrylate-maleic anhydride copolymer is used. The copolymer consists of 0.2-10 wt% maleic anhydride and 0-40 wt% alkyl (meth) acrylate. This MFT is 1-50
It is between (190 ℃ -2.16kg). The alkyl (meth) acrylate is as described above.

Polyamide (B2) means the following condensation products: (1) one or more amino acids, eg aminocaproic acid, 7-aminoheptanoic acid, 11
-Aminoundecanoic acid and 12-aminododecanoic acid or one or more lactams such as caprolactam, enanthlactam and lauryllactam, (2) salts or mixtures of one or more diamines such as hexamethylenediamine,
Dodecamethylenediamine, metaxylylenediamine, bis (p-aminocyclohexylmethane and trimethylhexamethylenediamine and diacids such as isophthalic acid, terephthalic acid, adipic acid, azelaic acid, suberic acid, sebacic acid and dodecanedicarboxylic acid, ( 3) A mixture of monomers that form a copolyamide.

It is also possible to use mixtures of polyamides. Preferably PA-6, PA-11, PA-12,
A copolyamide containing 6 and 12 units (PA-6 / 12), a copolyamide based on caprolactam, hexamethylenediamine and adipic acid (PA-6 / 6.6) is used. (B2) is a polyamide or a polyamide oligomer. Polyamide oligomers are described in European Patent EP 342066. Polyamide (B2) can have acid, amine or monoamine end groups. In the case of polyamides with monoamines it is possible to use chain limiters of the formula:

[0024]

[Compound 1]

(Wherein R ₁ is hydrogen or a linear or branched alkyl group having 20 or less carbon atoms, and R ₂ is a linear or branched alkyl group or alkenyl group having 20 or less carbon atoms, saturated or Unsaturated cycloaliphatic groups, aromatic groups or combinations thereof) The chain limiter can be, for example, laurylamine or oleylamine.

(B2) is preferably PA-6, PA-11 or PA-12. In another advantageous embodiment of the invention (B2) is a monoaminated oligomer of PA-6, preferably of molecular weight 1
It is an oligomer between 000 and 3500. The weight ratio of (B2) in B1 + B2 is preferably 0.1 to 60%. The reaction between (B1) and (B2) is preferably carried out in a molten state. For example, (B1) and (B2) are mixed in an extruder at a temperature of 230 to 250 ° C. The average residence time of the melt in the extruder is between 10 seconds and 3 minutes, preferably 1-2 minutes.

Polypropylene (B) having a polyamide graft chain is obtained by reacting (i) a homopolymer or copolymer (B3) of propylene having a grafted or copolymerized unsaturated monomer X with (ii) a polyamide (B2). Can be obtained at. The raw material for the production of (B3) can be a copolymer of propylene and unsaturated monomer X, or a polypropylene grafted with unsaturated monomer X. Is X copolymerizable with propylene?
Any unsaturated monomer having a functional group that can be grafted to polypropylene and that can chemically react with polyamide. This functional group is as defined above. In the case of grafted polypropylene, homopolymers or copolymers of propylene, such as (
Graft X onto polyethylene-propylene based propylene (in moles).
This grafting method is known. In the case of X grafted (B3), X is grafted in the first zone of the extruder and then compound (B2) is introduced in the second and third zones further downstream of the same extruder. (B2) is as defined above. The reaction between (B3) and (B2) is carried out under the same conditions as the reaction between (B1) and (B2). The weight ratio of (A) and (B) is
It is preferably between 2 and 4.

The mixture of the present invention can be made by melt mixing in an extruder (single screw or twin screw), a Bus kneader, a Brabender kneader and generally a device for blending thermoplastics. The composition according to the invention may further comprise at least one additive selected from the following: 1) dyes, 2) pigments, 3) brighteners, 4) antioxidants, 5) UV stabilizers.

The invention further relates to a film comprising the above composition. The present invention relates to a multilayer structure having this film or a layer made of the above composition, and a packaging material having this structure. In one embodiment of the present invention, there is provided a film having at least one layer of the composition of the present invention and at least one polypropylene layer adjacent thereto. The adhesion between these two layers is excellent. This film can be made by coextrusion.

Polypropylene is a homopolymer or copolymer of polypropylene. The comonomers may include: 1) α-olefins, preferably α-olefins having 4 to 30 carbon atoms, 2) dienes. The polypropylene may be a block copolymer of polypropylene. Examples include: 1) homopolymers of polypropylene, 2) blends of polypropylene with EPDM or EPR (about 1-20% of polypropylene).
Can include polyethylene). Polypropylene is a mixture of polymers (propylene is at least 50 mol%,
It is preferably 75 mol%). Polypropylene can have, for example, an MFI of 20-40 g / 10 min (230 ° C / 2.16 kg).

[0031]

【Example】

The following raw materials were used: EVOH E: MFI (210 ° C / 2.16kg) 18, melting point 183 ° C, crystallization temperature 160
Ethylene containing 38 mol% of ethylene having a Tg (glass transition temperature) of 61 ° C.
Vinyl alcohol copolymer. EVOH D: MFI (210 ℃ / 2.16kg) 15, melting point 188 ℃, crystallization temperature 163 ℃
And an ethylene-vinyl alcohol copolymer containing 29 mol% ethylene with a Tg (glass transition temperature) of 62 ° C. EVOH DC: MFI (210 ℃ / 2.16kg) 16, melting point 188 ℃, crystallization temperature 163 ℃
And an ethylene-vinyl alcohol copolymer containing 32 mol% of ethylene and having a Tg (glass transition temperature) of 62 ° C.

PP 3020 GN 3: Random weight of polypropylene supplied under the name of Appryl® with a melting point of 148 ° C. (10 ° C./min) and an MFI (210 ° C./2.16 kg) of 1.8. Coalescing. PP 3010 GN 5: A polypropylene block copolymer supplied under the name Appryl® with a melting point of 163 ° C (10 ° C / min) and an MFI (210 ° C / 2.16 kg) of 1.4. VESTOLEN P9000 (registered trademark): Hul with MFI (210 ℃ / 2.16kg) of 2 (Hul
s) Polypropylene supplied by the company. MOPLEN: Random polypropylene with an MFI of 2 (210 ° C / 2.16kg) containing 3% ethylene. COMP 1: Compatibilizer of ethylene-polypropylene copolymer containing 88 mol% polypropylene, grafted with 1% maleic anhydride and then condensed with oligomer of monoaminated polyamide-6 having a molecular weight of 2500. COMP 2: Compatibilizer of ethylene-polypropylene copolymer containing 88 mol% polypropylene, graphed with 1% maleic anhydride. Each mixture was kneaded with a bath (Buss, registered trademark) 15D kneader. The results are shown in [Table 1]. Is the ratio a weight ratio?

[0033]

[Table 1]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 23/08 C08L 23/08 51/06 51/06 // (C08L 23/08 C08L 23:10 23: 10) (C08L 29/04 23:10) (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL , PT, SE), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, MZ, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, B B, BG, BR, BY, BZ, CA, CH, CN, CR, CU, CZ, DE, DK, DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU , ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA , ZWF F term (reference) 3E086 AB01 AD30 BA04 BA15 BB05 CA01 DA08 4F071 AA15X AA20 AA29X AA33X AA36X AA54 AA76 AA77 AA88 AF08 AH04 BC01 4F100 BB69 BB69BB02 BB69J02BA01B01J0115A15A01A30A04A15A02B01B01B01B01J0115A01B01B01B01J0215A01B01B01B01B01B01B01J0115A15A15A15A15A15A15A01A15A01A01B01B01B01J0115A0A15A0A5A0A5A0A0A5A0A5A0A5A0A5A0A5A0A5A0A5A0A5A0A5A0A5A0A0A0A0A0A4

Claims (14)

[Claims] 1. A composition comprising (1) 55 to 99.5 parts by weight of an EVOH copolymer and (2) 0.5 to 45 parts by weight of polypropylene (A) and a compatibilizing agent (B). The ratio (A) / (B) of (B) and (B) is 1 to 5, and the ratio of MFI of EVOH to MFI (melt flow index) of polypropylene is 5 or more. 2. The composition according to claim 1, wherein the MFI of (A) is 0.5 to 3 (g / 10 minutes, 230 ° C./2.16 kg). 3. The composition according to claim 1, wherein the ratio of MFI of EVOH to MFI of polypropylene measured at 230 ° C. under a load of 2.16 kg is 5 to 25. 4. The composition of claim 3, wherein the ratio of MFI is 8-15. 5. The composition according to claim 1, wherein the weight ratio of (A) / (B) is 2-4. 6. (B) a polyethylene having a polyamide graft chain obtained by the reaction of (i) a copolymer (B1) obtained by grafting or copolymerizing an unsaturated monomer X to ethylene and (ii) a polyamide (B2). 6. The composition of any one of claims 1-5. 7. An ethylene-maleic anhydride copolymer and an ethylene-alkyl (meth) acrylate-anhydride, wherein (B1) is 0.2 to 10% by weight of maleic anhydride and 0 to 40% by weight of alkyl (meth) acrylate. 7. The composition of claim 6, selected from among maleic acid copolymer copolymers. 8. (B) is a graft of a polyamide obtained by the reaction of (i) a homopolymer or copolymer (B3) of propylene grafted or copolymerized with an unsaturated monomer X (B3) and (ii) a polyamide (B2). A polypropylene having a chain.
The composition according to any one of 1 to 5. 9. The composition according to claim 8, wherein (B3) is polyethylene-propylene grafted with maleic anhydride and containing propylene as a main component (in moles). 10. (B2) is based on PA-6, PA-11, PA-12, a copolyamide (PA-6 / 12) containing 6 and 12 as a unit, caprolactam, hexamethylenediamine and adipic acid. 6. A copolyamide (PAN6 / 6.6) selected from
10. The composition according to any one of 9. 11. (B2) is a monoaminated oligomer of PA-6.
The composition according to any one of 6 to 9. 12. A film comprising the composition according to any one of claims 1 to 11. 13. The film of claim 12 having at least one polypropylene layer. 14. A multilayer structure comprising the film according to claim 12 or 13, and a packaging material having this structure.