JP7107706B2 - Polyolefin composition and laminate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyolefin composition having excellent adhesion to polyolefins and ethylene-vinyl alcohol copolymers, as well as adhesiveness with excellent appearance, and a laminate using the same.

BACKGROUND ART Conventionally, polypropylene has been widely used as a thermoplastic molding material that is excellent in rigidity, heat resistance, transparency, and the like. Since this polypropylene is inferior in flexibility, when it is used as an adhesive resin composition, it is usually blended with a soft rubber component in order to increase flexibility and low-density polyethylene in order to increase cohesive strength of the adhesive resin. When a soft rubber component or low-density polyethylene is mixed with polypropylene in this manner, a polypropylene-based adhesive resin composition having improved adhesiveness can be obtained, but on the other hand, there is a problem that transparency and appearance deteriorate. rice field.

The poor appearance referred to here is referred to as streak or orange peel, and refers to streak-like appearance defects or mosaic-like appearance defects on the surface of the seat or cup. The deterioration of transparency and appearance is thought to be due to the difference in refractive index between polypropylene, which constitutes the sea phase, and the soft rubber component or low-density polyethylene, which constitutes the island phase, in the sea-island structure of the adhesive resin composition. be done. Patent Document 1 describes an adhesive resin composition containing 20 parts by weight of ethylene-butene-1 copolymer and 10% by mass of linear low-density polyethylene in order to achieve both adhesive strength and transparency. However, nothing is said about appearance.

Japanese Patent Application Laid-Open No. 2001-294836

Recently, there has been a growing demand for improving the transparency, appearance and adhesion of adhesive resin compositions. An object of the present invention is to provide an adhesive resin composition which has excellent adhesion to polyolefins and ethylene-vinyl alcohol copolymers and is capable of forming an adhesive resin layer having excellent transparency and appearance. Another object of the present invention is to provide a laminate including a layer comprising the adhesive resin composition and having excellent transparency, appearance and interlayer adhesion. Another object of the present invention is to provide a food cup formed from the laminate.

The present inventors arrived at the present invention as a result of earnest research in order to solve the above problems. That is, the present invention
(A) A copolymer containing propylene and an α-olefin having 2 to 20 carbon atoms (excluding propylene), when the total constituent components in the copolymer are 100 mol%, other than propylene 65 to 94% by mass of a propylene/α-olefin copolymer containing 5 mol% or less of constituent components derived from
(B) 1 to 20% by mass of at least one modified propylene-based (co)polymer selected from the following (b-1) and (b-2) graft-modified with an ethylenically unsaturated monomer;
(b-1) Propylene homopolymer (b-2) A copolymer of propylene and an α-olefin having 2 to 20 carbon atoms (excluding propylene) containing 10 moles of constituent components derived from the α-olefin % or less propylene/α-olefin random copolymer,
(C) Density is 0.86 g/cm ³ or more and 0.94 g/cm ³ or less, and is at least one selected from (c-1) and (c-2) below. 5 to 15% by mass of coalescence,
(c-1) Linear low-density polyethylene (c-2) Ethylene/α-olefin random copolymer having a molar ratio of ethylene and an α-olefin having 3 to 20 carbon atoms of 99.5/0.5 to 35/65 A polyolefin composition containing coalesced (provided that the total of (A), (B), and (C) is 100% by mass).
The present invention also provides a laminate having at least one layer containing the polyolefin composition.

The polyolefin composition of the present invention is excellent in adhesiveness, transparency and appearance. Furthermore, when the polyolefin composition of the present invention is used as an adhesive resin layer to form a laminate with other resin layers, it is possible to obtain a molded product with excellent interlayer adhesion, and at the same time, molding that requires high transparency and excellent appearance. products can be provided.

Embodiments of the present invention will be described below, but the present invention is not limited to these.
The polyolefin composition of the present invention contains a propylene/α-olefin copolymer (A), a modified propylene-based (co)polymer, and an ethylene-based (co)polymer (C).

<Propylene/α-olefin copolymer (A)>
The propylene/α-olefin copolymer (A) used in the present invention contains 5 mol % or less of α-olefin relative to propylene.
The α-olefin is not limited as long as it is other than propylene, but preferably includes ethylene having 2 carbon atoms and/or α-olefin having 4 to 20 carbon atoms. They may be used alone or in combination of two or more. Preferred α-olefins in the present invention are ethylene having 2 carbon atoms and α-olefins having 4 to 10 carbon atoms. Among them, ethylene having 2 carbon atoms and α-olefins having 4 to 8 carbon atoms are particularly preferable. .

The method for producing the propylene/α-olefin copolymer (A) is not particularly limited, and it can be produced by a known method using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. can. Moreover, a crystalline polymer can be preferably used, and it may be a random copolymer or a block copolymer. Furthermore, stereoregularity and molecular weight are not particularly limited as long as they satisfy moldability and have strength enough to withstand use when formed into a molded product. It is also possible to use a commercially available resin as it is. Such a propylene/α-olefin copolymer (A) is used in the composition of the present invention in an amount of 65 to 94% by mass, preferably 70 to 94% by mass.

From the standpoint of moldability, the 1/2 crystallization time of the propylene/α-olefin copolymer (A) at 110° C. is preferably 150 seconds or less, preferably 140 seconds or less.
The 1/2 crystallization time (t _1/2 ) is the time to reach 50% of the heat quantity when the area between the DSC heat quantity curve and the baseline in the isothermal crystallization process is taken as the total heat quantity. [See New Polymer Experiment Lecture 8 Physical Properties of Polymers (Kyoritsu Shuppan Co., Ltd.)]

Half crystallization time (t _1/2 ) measurements are made as follows. About 5 mg of the sample is packed in a dedicated aluminum pan, and using DSCPyris1 or DSC7 manufactured by PerkinElmer, the temperature is raised from 30 ° C. to 230 ° C. at 320 ° C./min, and after holding at 230 ° C. for 5 minutes, the temperature (230 ° C. ) to each isothermal crystallization temperature at a rate of 320° C./min, and the 1/2 crystallization time (t _1/2 ) is determined from the DSC curve obtained by holding at the isothermal crystallization temperature. When the crystal does not crystallize at 110°C, several measurements are made at an isothermal crystallization temperature of 110°C or lower for convenience, and the half crystallization time (t _1/2 ) is obtained from the extrapolated value.

<Modified propylene-based (co)polymer (B)>
The modified propylene-based (co)polymer (B) graft-modified with an ethylenically unsaturated monomer used in the present invention is a propylene-based polymer grafted with an ethylenically unsaturated monomer. The grafting amount is preferably 0.01 to 10% by mass, more preferably 0.1 to 5% by mass. In the case of such a graft amount, the adhesiveness to the base material, which is another resin layer constituting the laminate, is good, which is preferable.

The propylene-based polymer that is the base of the modified propylene-based (co)polymer of the present invention is a propylene homopolymer (b-1), or a random copolymer of propylene and other α-olefins (b -2). The propylene/α-olefin random copolymer (b-2) contains 10 mol% or less, preferably 7% or less of α-olefins other than propylene based on the total number of moles of propylene and other α-olefins. It is a random copolymer. α-olefins other than propylene are usually α-olefins having 20 or less carbon atoms, specifically ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, , 1-tetradecene, 1-octadecene and the like are used, each of which may be used alone or in combination of two or more.

Examples of ethylenically unsaturated monomers include unsaturated carboxylic acids or derivatives thereof, unsaturated nitriles, unsaturated epoxies, unsaturated amines, and the like. Of these, unsaturated carboxylic acids or derivatives thereof are preferred. Examples of the unsaturated carboxylic acid or derivative thereof include acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, nadic acid (trade name) (endosys-bicyclo[2,2 ,1]hept-5-ene-2,3-dicarboxylic acid), or derivatives thereof such as acid halides, amides, imides, anhydrides, esters, etc. Specifically, Examples include malenyl chloride, maleimide, maleic anhydride, citraconic anhydride, monomethyl maleate, dimethyl maleate, glycidyl maleate and the like. Among these, unsaturated dicarboxylic acids and their acid anhydrides are preferred, and maleic acid, nadic acid and their acid anhydrides are particularly preferred. Ethylenically unsaturated monomers may be used singly or in combination of two or more.

Various conventionally known methods can be employed to produce the modified product (B) by graft-copolymerizing the unsaturated ethylenic monomer with the propylene-based polymer. For example, there is a method in which a propylene-based polymer is melted, a graft monomer is added, and graft copolymerization is performed, or a method in which the polymer is dissolved in a solvent, a graft monomer is added, and graft copolymerization is performed. In any case, the reaction is preferably carried out in the presence of a radical initiator in order to efficiently graft-copolymerize the graft monomer. The grafting reaction is usually carried out at a temperature of 60-350°C. The ratio of the radical initiator to be used is usually in the range of 0.001 to 1 part by weight per 100 parts by weight of the polypropylene polymer before modification.

Radical initiators include organic peroxides, organic peresters such as benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(peroxidobenzoate)hexyne- 3,1,4-bis(tert-butylperoxyisopropyl)benzene, lauroyl peroxide, tert-butylperacetate, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3,2,5- Dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl perisobutyrate, tert-butyl per-sec-octoate, tert-butyl perpivalate , cumyl perpivalate and tert-butyl perdiethyl acetate, as well as other azo compounds such as azobisisobutyronitrile, dimethylazoisobutyrate. Among these are dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-di(tert- Dialkyl peroxides such as butylperoxy)hexane, 1,4-bis(tert-butylperoxyisopropyl)benzene, and the like are preferred. Such modified propylene-based (co)polymer (B) is used in the composition according to the present invention in an amount of 1 to 20% by weight, preferably 3 to 15% by weight. It is preferable that the amount of the modified propylene-based (co)polymer (B) is within this range because the adhesion is good.

<Ethylene-based (co)polymer (C)>
In the present invention, linear low-density polyethylene (c-1) and/or ethylene/α-olefin copolymer (c-2) are used as the ethylene-based (co)polymer (C).
The ethylene-based (co)polymer (C) used in the present invention has a density of 0.860 g/cm ³ or more and 0.940 g/cm ³ or less, preferably 0.860 to 0.930 g/cm ³ . It is in. When the density is within the above range, the effect of improving the transparency and adhesive strength of the composition is excellent, and when the density is within the preferred range, the above properties are further improved.

Linear low-density polyethylene (c-1) and ethylene/α-olefin copolymer (c-2) are homopolymers of ethylene or random copolymers of ethylene and α-olefins having 3 to 20 carbon atoms. It is a coalescence, and when all the constituent components in the copolymer are 100 mol%, the ethylene content is 99.5 to 35 mol%, preferably 99.0 to 40 mol%, and the α-olefin content is 65 to 0.5 mol %, preferably 60 to 1.0 mol %. When the content of the monomer is within the above range, a composition having excellent effects of improving transparency, appearance and adhesion can be obtained.

Examples of α-olefins to be copolymerized with ethylene in the linear low-density polyethylene and/or ethylene/α-olefin copolymer (C) include propylene, 1-butene, 3-methyl-1-pentene, 4-methyl- Examples include α-olefins having 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms such as 1-pentene, 1-hexene, 1-octene, 1-decene, 1-tetradecene and 1-octadecene. These α-olefins can be used singly or in combination of two or more.

The ethylene-based (co)polymer (C) can be obtained by a known method, usually by copolymerizing ethylene alone or ethylene and α-olefin in the gas phase or liquid phase in the presence of a transition metal catalyst. Obtainable. There are no particular restrictions on the catalyst, polymerization method, etc. for production, for example, Ziegler type catalyst, Phillips type catalyst, metallocene type catalyst, etc. are used, and polymerization is performed by a polymerization method such as a gas phase method, a solution method, or a bulk polymerization method. be able to. Such an ethylene-based (co)polymer (C) is used in the composition according to the invention in an amount of 5-15% by weight, preferably 5-13% by weight. When the amount of the ethylene-based (co)polymer (C) is within this range, the adhesiveness, transparency and appearance are good, which is preferable.

The polyolefin composition of the present invention preferably has a 1/2 crystallization time at 110° C. of 100 seconds or less, preferably 80 seconds or less, from the standpoint of moldability. Since other components are contained, the crystallization time may usually be shorter than 1/2 of the propylene/α-olefin copolymer (A) used, but the difference depends on the constituent components. , is not particularly limited.

<Other ingredients>
In addition, the polyolefin composition of the present invention may contain known process stabilizers, heat stabilizers, weather stabilizers, antistatic agents, pigments, dyes, rust inhibitors, and pressure-sensitive adhesives as long as the objects of the present invention are not impaired. etc. can also be added. Examples of adhesives include rosin derivatives, terpene resins, petroleum resins, and hydrides thereof. Among these, hydrogenated terpene resins and hydrogenated petroleum resins are preferred.

<Preparation of polyolefin composition>
The method for preparing the polyolefin composition of the present invention is not particularly limited, but the propylene/α-olefin copolymer, modified propylene-based (co)polymer (B), and ethylene-based (co)polymer (C) In various known methods, for example, a Henschel mixer, a v-blender, a ribbon blender, a method of mixing with a tumbler blender, or after mixing, a single-screw extruder, a twin-screw extruder, a kneader, a Banbury mixer, etc. After melt-kneading, granulation. Alternatively, a pulverization method may be employed.

<Laminate>
The polyolefin composition of the present invention is suitably used as an adhesive resin layer for laminates. Various thermoplastic resins such as polyolefins, polyesters, polyamides, and ethylene-vinyl alcohol copolymers can be used as resins for the thermoplastic resin layers constituting the layers other than the adhesive resin layer, which constitute the laminate. Among them, a polyolefin resin layer and an ethylene-vinyl alcohol copolymer-containing layer are preferably used. The ethylene/vinyl alcohol copolymer-containing layer is not particularly limited as long as it contains 51 to 100% by mass of the ethylene/vinyl alcohol copolymer as a main component. Moreover, examples of the resin that may be contained in the content layer include the aforementioned polyolefins, polyesters, polyamides, and the like.

As the ethylene/vinyl alcohol copolymer, a copolymer containing 20 to 50 mol %, preferably 25 to 48 mol %, of polymerized units derived from ethylene is desirable. These can be produced by saponifying the corresponding ethylene/vinyl acetate copolymer by a conventional method.

The laminate of the present invention preferably has an ethylene/vinyl alcohol copolymer layer laminated on at least one side of the polypropylene-based composition layer. The number of layers of the laminate is not particularly limited and is appropriately selected according to the purpose, and the laminate may be a laminate obtained by repeatedly laminating partial laminates.

The laminate of the present invention can be produced, for example, by melting the composition or resin of each layer and laminating them in a molten state. Other layers to be laminated are not particularly limited as long as they include the laminate structure.

The laminate can be produced by a known coextrusion method. Specifically, it can be produced by a known co-extrusion molding method such as inflation molding, cast molding, extrusion coating molding and the like. The laminate of the present invention can be suitably used as films for packaging foods, daily necessities, cups, bottles, packaging materials, and the like. Since the propylene composition of the present invention has high transparency, the contents can be visually recognized from the outside, and the appearance is also excellent.

EXAMPLES The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples. In the examples, the adhesive strength (N/15 mm) was measured according to the method described in JIS K6854 (test piece: sheet, width of test piece: 15 mm).

(various measurement methods)
In the present examples and the like, measurements were carried out according to the following methods.
[Melt flow rate (MFR)]
Measurements were performed at 230° C. under a load of 2.16 kg according to ASTM D1238.
[density]
Density was measured according to JIS K7112.
[Crystallization speed]
Crystallization rate was measured at 110° C. 1/2 crystallization time.
Polyolefins used in Examples and Comparative Examples are shown below. Unless otherwise specified, all were prepared by polymerization according to a conventional method.
PP-1: Polypropylene (melt flow rate 2.0 g/10 minutes, density 0.90 g/cm ³ , 1/2 crystallization time 150 seconds, ethylene content 3.6 mol %)
PP-2: polypropylene (melt flow rate 2.0 g/10 minutes, density 0.90 g/cm ³ , 1/2 crystallization time 190 seconds, ethylene content 6.6 mol %)
Modified PP-1: Maleic anhydride-modified polypropylene (MAH-PP)
(Melt flow rate 100 g/10 minutes, density 0.90 g/cm ³ , ethylene content 5.0 mol %)
LLDPE-1: polyethylene (melt flow rate 2.0 g/10 min, density 0.90 g/cm ³ , hexene content = 6.0 mol%)

(Example 1)
<Production of polyolefin composition>
PP-1: 85% by mass, modified PP-1: 5% by mass, and LLDPE-1: 10% by mass are melt-kneaded at 230 ° C. using a twin-screw kneader (manufactured by Japan Steel Works, TEX-30), A polyolefin composition for adhesion was obtained. The resulting composition had a melt flow rate of 2.4 g/10 minutes and a density of 0.90 g/cm ³ . The 1/2 crystallization time at 110°C was 75 seconds.

<Production of 5-layer laminate>
A five-layer sheet was formed by co-extrusion of layers having the constitution shown below under the following conditions.
[inner layer, outer layer]
Commercially available polypropylene (F113G manufactured by Prime Polymer Co., Ltd., MFR=1 g/10 min) was extruded at 230° C. using a screw of 40 mm and L/D=28 as the inner and outer layers.

[Middle layer]
A commercially available ethylene/vinyl alcohol copolymer (Kuraray J171B, MFR=8.0 g/10 min) was extruded as an intermediate layer at 220° C. using a screw of 30 mm and L/D=24.

[Adhesive resin layer]
As an adhesive resin layer, the above polyolefin composition was extruded at 220° C. using a screw of 40 mm and L/D=28.

[Laminate molding conditions]
The extruded resins for the outer layer, inner layer, intermediate layer, and adhesive layer are laminated in the feedblock in the order of inner layer, adhesive layer, intermediate layer, adhesive layer, and outer layer. The die temperature is 220° C., and the laminate of each resin co-extruded into a film having a thickness of about 850 μm is taken up at a speed of 1 m/min while being cooled by a chill roll. The thickness of each layer was outer layer/adhesive layer (1)/intermediate layer/adhesive layer (2)/inner layer=350/50/50/50/350 μm. Table 1 shows the interlayer adhesion of the adhesive layer (1)/intermediate layer of the molded laminate.

(Example 2)
<Production of polyolefin composition>
A polyolefin composition and a laminate were produced in the same manner as in Example 1 according to the formulation shown in Table 1. Table 1 shows the results of interlayer adhesion of the obtained laminate.
(Comparative Examples 1 to 3)
A polyolefin composition and a laminate were produced in the same manner as in Example 1 according to the formulation shown in Table 1. Table 1 shows the results of interlayer adhesion of the obtained laminate.
The appearance of the film was evaluated with ○ when the appearance was good and x when the appearance was bad.

Claims (5)

(A) A copolymer containing propylene and an α-olefin having 2 to 20 carbon atoms (excluding propylene), when the total constituent components in the copolymer are 100 mol%, other than propylene 65 to 94% by mass of a propylene/α-olefin copolymer containing 5 mol% or less of constituent components derived from
(B) 1 to 20% by mass of at least one modified propylene-based (co)polymer selected from the following (b-1) and (b-2) graft-modified with an ethylenically unsaturated monomer;
(b-1) Propylene homopolymer (b-2) A copolymer of propylene and an α-olefin having 2 to 20 carbon atoms (excluding propylene) containing 10 moles of constituent components derived from the α-olefin % or less propylene/α-olefin random copolymer,
(C) Density is 0.86 g/cm ³ or more and 0.94 g/cm ³ or less, and is at least one selected from (c-1) and (c-2) below. 5 to 15% by mass of coalescence,
(c-1) Linear low-density polyethylene (c-2) Ethylene/α-olefin random copolymer having a molar ratio of ethylene and an α-olefin having 3 to 20 carbon atoms of 99.5/0.5 to 35/65 A polyolefin composition containing coalescence (where the total of (A), (B), and (C) is 100% by mass),
A polyolefin composition, wherein the 1/2 crystallization time of the polyolefin composition at 110°C is 100 seconds or less . 2. The polyolefin composition according to claim 1, wherein the ethylenically unsaturated monomer of the modified propylene-based (co)polymer (B) is an unsaturated carboxylic acid or derivative thereof. 3. The polyolefin composition according to claim 1, wherein the propylene/α-olefin copolymer (A) has a 1/2 crystallization time at 110° C. of 150 seconds or less. A laminate obtained by laminating an adhesive resin layer containing the polyolefin composition according to any one of claims 1 to 3 and at least one layer selected from a polyolefin resin layer and an ethylene-vinyl alcohol copolymer-containing layer. A food cup comprising the laminate of claim 4 .