JP3087919B2 - Laminate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminate of an ethylene-vinyl alcohol copolymer, and more particularly to a laminate having a regrind layer.

[0002]

2. Description of the Related Art Laminated products of polyolefin resins such as polyethylene and polypropylene and ethylene-vinyl alcohol copolymer (hereinafter abbreviated as EVOH) are widely used as containers, sheets and films. These laminates are laminated as a so-called three or more layer structure in which an EVOH layer is used as an intermediate layer and a polyolefin layer is provided on both surfaces thereof in order to utilize the characteristics of each resin. That is, the polyolefin resin is not only excellent in water resistance and mechanical properties, but also good in moldability and inexpensive, but the gas barrier property is extremely poor, while EVOH is poor in gas barrier property. Although it is excellent, its performance is significantly deteriorated in a high humidity atmosphere, so that it is often laminated so as to have the above configuration in order to compensate for the disadvantages of both the EVOH and the polyolefin resin.

[0003] The laminate is used for containers such as bottles and cups, sheets for packaging, films and the like by manufacturing methods such as vacuum forming, compression molding, blow molding and injection molding. In this manufacturing process, a regrind (scrap) is generated due to a scrap, an end portion, or a defective product of the product, and the occurrence rate may be 50% by weight or more, which is a problem.

As a countermeasure, a method of providing a regrind layer for the purpose of recycling scraps on a laminate is generally known. That is, when a laminate of EVOH and a polyolefin resin is produced using such a regrind layer, the laminate has at least a five-layer structure of a polyolefin resin layer / a regrind layer / an EVOH layer / a regrind layer / a polyolefin resin layer. It is used as a laminate. The regrind is re-melted to form a mixture of EVOH and polyolefin resin.
The compatibility between VOH and the polyolefin resin is poor, and depending on the composition of the regrind layer, defects such as peeling at the interface of the regrind layer, disorder of the layer, wavy pattern and the like, and furthermore, the rigidity of the product may occur in the five-layer laminate. And a decrease in strength.

As a countermeasure against this, a general formula M _x Al _y (OH) _{2x + 3y-2z} (E) _z · aH ₂ O (where M is M
A method of adding a hydrotalcite-based compound represented by g, Ca or Zn, E to CO ₃ or HPO ₄ , x, y, z to positive numbers, and a to 0 or positive numbers) to the regrind layer has also been studied. However, in this case, EVO in the regrind composition
There is a disadvantage that the effect is significantly reduced when the H content is increased. To solve these disadvantages, Japanese Patent Laid-Open No.
-269528 and Japanese Patent Application Laid-Open No. 1-275041 have been filed.

[0006]

However, in the former publication, it is necessary to provide a buffer layer between the outer layer and the regrind layer, and the number of layers must be increased as a whole, and the process becomes complicated. Further, in the latter publication, a measure is disclosed in which an amorphous ethylene-propylene copolymer is blended in a regrind layer for the purpose of improving the drop strength and rigidity (toughness) of the laminate (container), This aims to increase the drop strength with a stiff regrind layer, and achieves the above purpose, but has no effect of improving delamination, layer disorder and generation of wavy patterns, etc., and is still completed. At present, there is no method. An object of the present invention is to provide a laminate which is free from delamination, layer disturbance and wavy pattern of the laminate, and which is excellent in impact resistance.

[0007]

The object of the present invention is to provide a laminate in which a polyolefin resin layer / regrind layer / EVOH layer / regrind layer / polyolefin resin layer is laminated in this order. -Vinyl alcohol copolymer (B) polyolefin-based resin (C) polyolefin-based resin to which an ethylenically unsaturated carboxylic acid or a derivative thereof is subjected to a graft reaction, and further averaged
It comprises a composition of a graft polymer obtained by reacting a polyamide having a degree of polymerization of 200 or more (A) :( B) :( C) = 1: 1 to 1
This is achieved by using a composition that is 20: 0.01 to 2 (parts by weight). Hereinafter, the present invention will be described in detail.

The (A) EVOH in the EVOH layer and the regrind layer of the center layer of the laminate of the present invention is a saponified copolymer of ethylene and vinyl acetate and has an ethylene content of 20 to 60 mol%, preferably 25 to 50 mol%. It has a mole ratio of 55 mol% and a saponification degree of the vinyl acetate component of 95 mol% or more. If the ethylene content is less than 20 mol%, the oxygen barrier property at high humidity decreases, while if it exceeds 60 mol%, physical properties such as oxygen barrier property and printability deteriorate. On the other hand, if the saponification degree is less than 95 mol%, the oxygen barrier property and the moisture resistance are reduced.

The saponified copolymer may further contain a small amount of propylene, isobutene, α-octene, α-dodecene,
Α-olefins such as octadecene, unsaturated carboxylic acids or salts thereof, partially alkyl esters, fully alkyl esters, nitriles, amides, comonomer such as anhydrides or unsaturated sulfonic acids or salts thereof as copolymerizable components. Absent. In the present invention, JIS K is used as EVOH.
The melt index (referred to as MI) is 1 to 10 when measured at 210 ° C. under a load of 2160 g based on -6760.
Those having 0 g / 10 min, preferably 2 to 30 g / 10 min are suitably used.

The resin of the polyolefin resin layer of the outer layer of the laminate of the present invention and the polyolefin resin (B) in the regrind layer are linear low density / medium density / high density polyethylene, ionomer, ethylene-propylene copolymer. Coalescence, crystalline polypropylene, polybutene, ethylene-vinyl acetate copolymer with a relatively small vinyl acetate content, etc. are used, especially low-density polyethylene, medium-density polyethylene, high-density polyethylene, and isotactic polypropylene are practically important. is there. JI as polyolefin resin
210 ° C, 2160g load based on SK-6760
Has a melt index of 0.1 to 50 g /
Ten minutes are advantageously used.

In the present invention, the composition of the EVOH and the polyolefin resin of the regrind layer is such that (B)
Is in the range of 1 to 20 parts by weight, delamination and layer disorder,
Since a drawback such as a wavy pattern occurs, a compatibilizer (C) is blended in order to solve the drawback. (C) is a graft polymer obtained by subjecting a polyolefin resin to a graft reaction with an ethylenically unsaturated carboxylic acid or a derivative thereof, and further reacting the carboxylic acid or a derivative thereof with a polyamide. The graft polymer is obtained by dissolving or suspending the polyolefin resin in an appropriate solvent, or in a molten state, activating the polyolefin resin chain with a peroxide or diazo-based initiator to obtain an ethylenically unsaturated carboxylic acid. Alternatively, it is produced by graft-polymerizing a derivative thereof to obtain a polymer, and mixing the polymer and polyamide in a molten state.

The polyolefin resins mentioned above include linear low density / low density / high density polyethylene, ionomer, ethylene-propylene copolymer, crystalline polypropylene, polybutene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid Ester copolymers and the like can be mentioned. Particularly, linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, and crystalline polypropylene are practically important.

The ethylenically unsaturated carboxylic acid or its derivative to be grafted onto the backbone polymer is acrylic acid,
Methacrylic acid, crotonic acid, maleic acid, fumaric acid, unsaturated carboxylic acids such as itaconic acid or anhydrides thereof,
Half ester and the like. The polyamide is produced by a known method such as polyaddition of lactam, polycondensation of aminocarboxylic acid, and polycondensation of diamine and dicarboxylic acid.

Specific examples of the polyamide raw material include ε
Lactams such as caprolactam, enantholactam, capryllactam, lauryl lactam, α-pyrrolidone, α-piperidone, ω such as 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid -Amino acids, adipic acid, glutaric acid, pimelic acid, speric acid, azelaic acid, sebacic acid, undecandioic acid, dodecadionic acid, hexadecadionic acid, hexadecenedionic acid, eicosandioic acid, eicosadienedioic acid, diacid Glycolic acid, 2,
2,4-trimethyladipic acid, xylylenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, dibasic acids such as isophthalic acid, hexamethylenediamine, tetramethylenediamine, nonamethylenediamine, undecamethylenediamine, Diamines such as dodecamethylenediamine, 2,2,4 (or 2,4,4) -trimethylhexamethylenediamine, bis- (4,4′-aminocyclohexyl) methane, and metaxylylenediamine are exemplified. Monoamines such as laurylamine and oleylamine can also be used as appropriate for the purpose of controlling the molecular weight.

In the production of the graft polymer, a Brabender, a bus blender, a single screw extruder, a Weiner and a Friedler type twin screw extruder are used. The degree of polymerization of the polyolefin resin used is 350 to 4500
0, preferably about 500 to 10,000 are selected. Melt index (230 ° C, load 2160g)
As a practical example, about 0.1 to 50 g / 10 minutes is practical.

The reaction ratio between the polyolefin resin and the ethylenically unsaturated carboxylic acid or its derivative is 100 / 0.05 to 100/10, preferably 100/100, in terms of weight ratio.
0.3 to 100/3. If it is less than 100 / 0.05, the effect of improving the compatibility is insufficient, and if it exceeds 100/10, the viscosity during molding is remarkably increased and the practicality is poor. Also, the average degree of polymerization of the polyamide is required to be 200 or more,
1000 or less is practical , preferably about 200 to 500, and the reaction ratio is preferably 0.01 to 1 mol, preferably 0.05 to 0.9 mol per carboxyl group. Further, another resin such as polyamide may be further added to the above graft polymer, if necessary.

In the regrind layer of the present invention, (A)
The mixing ratio of (B) and (C) is (A) :( B) :( C) = 1: 1 to 2
It is essential that the ratio be 0.01: 2 to 2 (parts by weight), and preferably (A) :( B) :( C) = 1: 1 to 10: 0.05 to 0.5.
(Parts by weight). When the blending ratio of (B) is less than 1 part by weight, the processability such as stretchability is reduced, and the adhesion between the regrind layer and the outer polyolefin resin layer is deteriorated. , Impact resistance (fall strength) is significantly reduced. Conversely, if the blending ratio of (B) exceeds 20 parts by weight, the recycling rate of scrap decreases, which is not preferable.

If the compounding ratio of (C) is less than 0.01 parts by weight, the compatibility between (A) and (B) is reduced, and the effect of adding (C) is lost. Conversely, if the compounding ratio of (C) exceeds 2 parts by weight, a flow mark or a gel is generated during the production of the laminate, resulting in poor appearance and poor workability. Such a regrind layer
(A), (B) and (C) can be produced by melt molding.
Further, any of (A), (B), and (C) may be added to the scrap pulverized product to adjust the mixing ratio to form a regrind layer.

Further, (A),
As components other than (B) and (C), general formula M _x Al _y (OH)
_{2x + 3y-2z} (E) _z · aH ₂ O (where M is Mg, Ca or Z
n and E are CO ₃ or HPO ₄ , x, y, and z are positive numbers, and a is 0 or a positive number). By adding the hydrotalcite-based compound, a better long-run property can be obtained.

[0020] Illustrative of such compounds, for example, _{Mg 4. 5 Al 2 (OH} ) 13 CO 3 · 3.5H 2 O, Mg 5 Al
₂ (OH) ₁₄ CO ₃ .4H ₂ O, Mg ₆ Al ₂ (OH) ₁₆ CO _{3.
4H 2 O, Mg 8 Al 2} (OH) 20 CO 3 · 5H 2 O, Mg 10
Al ₂ (OH) ₂₂ (CO ₃ ) ₂ .4H ₂ O, Mg ₆ Al ₂ (OH) _{16
HPO 4 · 4H 2 O, Ca} 6 Al 2 (OH) 16 CO 3 · 4H
₂ O, Zn ₆ Al ₆ (OH) ₁₆ CO ₃ .4H ₂ O, and the like.

Further, the present invention is not limited to the above. For example, Mg ₂ Al (O
Even H) ₉ · 3H ₂ part of OH in O is more or those not shown explicitly in such formula is substituted with CO ₃ or HPO ₄ is what is the removal of crystal water (a = 0) The same effect can be expected. In particular, compounds in which M is Mg and E is CO ₃ show the most remarkable effects.

The compound has a total amount of (A), (B) and (C) of 10
0.005 to 5 parts by weight, preferably 0.
It is used in the range of 01 to 1 part by weight. When the amount of the compound is less than 0.005 parts by weight, the long-run processability decreases,
On the other hand, if it exceeds 5 parts by weight, the transparency, stretchability,
Flexibility is reduced. The compound may be present in the mixture of (A), (B) and (C) in any form, and there is no particular limitation on the timing of its addition. After that, a method of mixing with (A) and (C) is adopted.

As a method of forming a laminate using a regrind having such a composition, usually, extrusion is often performed.
Actually, a laminate of a polyolefin resin layer / EVOH layer / polyolefin resin layer ( adhesive resin layers such as carboxylic acid-modified olefin resin are provided on both sides of the EVOH layer as required to form a five-layer structure). Starting with molding,
The scrap generated during the forming process is sequentially crushed, and the component (C) is adjusted to the mixing ratio according to the present invention (if necessary, the component (Α) or (Β) is separately added). To obtain a laminate of the present invention. As a method for adding the component (C), a method in which the component (C) is previously added to a polyolefin-based resin layer or an EVOH layer is also useful.

At the time of such molding, a plasticizer (polyhydric alcohol, etc.), a stabilizer, a surfactant, a crosslinkable substance (epoxy compound, polyvalent metal salt, inorganic or organic polybasic acid or salt thereof, etc.) ), Fillers, coloring agents, and reinforcing agents such as fibers (glass fibers, carbon fibers, etc.) known in the art. In addition, other thermoplastic resins can be blended in an appropriate amount. Examples of such other thermoplastic resins include polyolefins that do not overlap with the resin component forming each layer or modified polyolefins obtained by craft-modifying these with unsaturated carboxylic acids or derivatives thereof. , Polyamide, polyvinyl chloride, polyvinylidene chloride, polyester, polystyrene, polyacrylonitrile, polyurethane, polyacetal, polycarbonate, melt-moldable polyvinyl alcohol resin, and EVOH.

In producing the laminate of the present invention,
Lamination is performed in the order of polyolefin-based resin layer / regrind layer / EVOH layer / regrind layer / polyolefin-based resin layer. Examples of the lamination method include not only the method of multi-layer simultaneous extrusion as described above, but also the above-described methods. (Film)
And a method combining the above two methods (for example, an EVOH sheet is laminated in a sandwich form using an adhesive with a regrind sheet,
Thereafter, a polyolefin-based resin is melt-extruded onto the laminate sheet to form a laminate, or a melt coating method.

In the case of production by multi-layer simultaneous extrusion, after melt kneading with an extruder corresponding to the resin of each layer, the resin can be extruded into a predetermined shape through a multi-layered multiple die such as a T-die and a circular die. In the laminating method, a known adhesive such as an organic titanium compound, an isocyanate compound, or a polyester compound is used.

Further, the laminate of the present invention comprises a polyolefin resin layer / regrind layer / EVOH layer / regrind layer /
It is essential to be laminated in the order of the polyolefin resin layer, but polyester, polyamide, copolymerized polyamide, polyvinyl chloride, polyvinylidene chloride, acrylic resin, styrene resin, on each layer or outside the laminate. Resin layers such as vinyl ester resins, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, chlorinated polypropylene, organic titanium compounds, isocyanate compounds, polyester compounds and linear low-density polyethylene, low-density polyethylene, high-density polyethylene, polypropylene, Adhesives such as compounds obtained by grafting an ethylenically unsaturated carboxylic acid or a derivative thereof to an olefin resin such as an ethylene-vinyl acetate copolymer, and a ternary copolymer compound of ethylene-ethyl acrylate-maleic anhydride There may be laminated, polyolefin resin layer of the present invention optionally, regrind layer and the EVOH layer or the like may be laminated again.

The shape of the laminate may be any shape, and examples thereof include a film, a sheet, a tape, a bottle, a pipe, a filament, and an extrudate having a modified cross section. The obtained laminate may be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making, deep squeezing, box processing, tube processing, split processing, etc. as necessary. It can be carried out. Further, the laminate of the present invention, in particular, a film sheet can be stretched as necessary to improve its physical properties.

The stretching may be either uniaxial stretching or biaxial stretching, and the effect of the present invention can be obtained by stretching as high as possible. In the case of uniaxial stretching, it is preferably at least 1.5 times, particularly preferably at least 2 times. In the case of biaxial stretching, the area ratio is 1.5 times or more, especially 2 times or more, and more preferably 4 times or more.
It is preferable that the number be twice or more. As a stretching method, in addition to a roll stretching method, a tenter stretching method, a tubular stretching method, a stretch blow method, and the like, a deep drawing method, a vacuum forming method, or the like having a high stretching ratio can be employed. In the case of biaxial stretching, any of a simultaneous biaxial stretching method and a sequential biaxial stretching method can be adopted. The film, sheet, container or the like obtained from the laminate of the present invention is useful as various packaging materials such as foods, pharmaceuticals, industrial chemicals, and agricultural chemicals.

[0030]

The laminate of the present invention has a five-layer structure of at least a polyolefin resin layer / regrind layer / EVOH layer / regrind layer / polyolefin resin layer, wherein (A) EVOH and (B) polyolefin. By using a regrind layer composed of a base resin and a specific graft copolymer (C), a molded product excellent in impact strength without peeling at the interface of the regrind layer, disorder of the layer, wavy pattern, etc. Can be obtained.

[0031]

Next, the present invention will be described specifically with reference to examples. Hereinafter, "%" is expressed on a weight basis unless otherwise specified. Sample preparation

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

In Table 3, the composition ratios of (c) / (b) (mo
Ratio) is different from the number of moles of the terminal amino groups of the polyamide (c).
It represents the ratio of the number of moles of the saturated carboxylic acid (II). Example 1
6 Using a regrind (scrap) material having the composition shown in Table 5, a laminate of the present invention was produced under the following conditions. The first layer structure of a laminate (1): a polyolefin resin second layer (2): regrind material third layer (3): adhesive * fourth layer (4): EVOH fifth layer (5): adhesion Agent * 6th layer ( 6 ): regrind 7th layer ( 7 ): polyolefin resin * Modified polyethylene (MI = 2.0) obtained by grafting 0.1% by weight of maleic anhydride to polyethylene ) Is (1) / (2) / (3) / (4) / (5)
/ (6) / (7) = 75/300/50/120/50
/ 300/75 7-layer laminate

Molding conditions and extruder: as shown in Table 4.

[Table 4]

Die: T-die with 4 types of 7-layer combining adapter, 450 mm width Extrusion temperature: Extruder for 1st, 7th layer, 2nd, 6th layer, 3rd, 5th layer C ₁ = 190 ° C. , C ₂ = 200 ° C. C ₃ = 210 ° C., C ₄ = 220 ° C. Extruder for fourth layer C ₁ = 180 ° C., C ₂ = 200 ° C. C ₃ = 220 ° C., C ₄ = 220 ° C. Combining adapter 220 ° C. T-die 220 ° C. The results are shown in Table 5.

Comparative Examples 1 to 4 Laminates were prepared under the same conditions as in Example 1 except that the EVOH, the polyolefin resin and the regrind component were changed as shown in Table 5.

[0038]

[Table 5]

1) Judgment by a surface roughness meter: When the total thickness fluctuates by 40% or more with respect to the average total thickness due to fluctuations in the thickness of the regrind layer. Case: △ 場合 When the value fluctuated less than 10%: ・ was evaluated.

2) A hollow container (diameter: 81.2 mm, depth: 70 mm, capacity: 230 cc) was prepared from the laminate (sheet).
The state of the hollow container was examined by filling it with water and letting it fall. Test method: Pour water up to 95% capacity into the above hollow container, place a lid of 50μ thick propylene copolymer with a 10μ thick aluminum foil, at 200 ° C, seal pressure 3.0kg.
/ Cm ² , the container mouth was sealed in 2 seconds. Then 20 ℃ ×
After standing at 65% RH for 24 hours, the container was dropped from a height of 1 m onto a concrete block to check the condition of the container. -Judgment criteria: No abnormality ... ○ Deformation of container ... △ Liquid leakage occurred, layer peeling occurred ×. As shown in the evaluation results in Table 5, the laminate film of the present invention is smooth, has no undulation or delamination, and exhibits physical properties excellent in impact strength.

[0041]

[Effect] The laminate of the present invention is very useful as a packaging material for various products such as foods, pharmaceuticals, industrial chemicals, agricultural chemicals, etc. because the surface of the laminate is smooth and has excellent impact resistance without waving or delamination. .

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-262640 (JP, A) JP-A 1-275041 (JP, A) JP-A-59-215864 (JP, A) 227347 (JP, A) JP-A-3-227346 (JP, A) JP-A-3-227345 (JP, A) JP-A-3-227344 (JP, A) JP-A-3-227339 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 1/00-35/00

Claims (2)

(57) [Claims] 1. A laminate in which a polyolefin resin layer / regrind layer / ethylene-vinyl alcohol copolymer layer / regrind layer / polyolefin resin layer is laminated in this order, wherein the regrind layer comprises (A) ethylene-vinyl Alcohol copolymer (B) Polyolefin-based resin (C) Polyolefin-based resin is further averaged by graft reaction of ethylenically unsaturated carboxylic acid or its derivative.
It comprises a composition of a graft polymer obtained by reacting a polyamide having a degree of polymerization of 200 or more (A) :( B) :( C) = 1: 1 to 1
20: 0.01 to 2 (parts by weight). 2. The laminate according to claim 1, wherein an adhesive layer is laminated between the regrind layer and the ethylene-vinyl alcohol copolymer layer.