JP7176822B2 - Easy-peelable resin composition and sealing material comprising the same - Google Patents

Description

The present invention relates to novel resin compositions. More particularly, it relates to a resin composition that exhibits excellent sealing properties and easy opening properties for various plastic containers.

BACKGROUND ART Plastic containers with easy-to-open lids are widely used as containers for various foods and drinks such as instant noodles, jelly, yogurt, and tofu, as well as pharmaceuticals. Various polymer compositions have been used for the sealing layer of such easy-open lid materials. For example, compositions of ethylene/vinyl acetate copolymers or ethylene/ethyl acrylate copolymers and tackifying resins, and compositions obtained by blending these with polyethylene or low-crystalline ethylene/α-olefin copolymers, It is known to be an excellent sealing material having sealing properties and easy opening properties (easy peel properties). However, ethylene/vinyl acetate copolymers and ethylene/ethyl acrylate copolymers generally have low softening points and may lack heat resistance. On the other hand, compositions containing resins with high softening points such as high-pressure polyethylene and linear low-density polyethylene may exhibit poor low-temperature sealability when the density is high, and may cause stickiness when the density is low. became. In recent years, polyester-based resins (hereinafter referred to as PET resins), which have good transparency and excellent fragrance retention, have been widely used. There were problems such as insufficient strength.

In Patent Document 1, 30 to 95 parts by weight of an ethylene copolymer component (A) of which at least half is copolymerized in the presence of a single-site catalyst, and 0 to 55 parts by weight of a crystalline olefin (co)polymer component (B). An ethylene copolymer composition composed of parts by weight and 5 to 30 parts by weight of a tackifying resin (C) has been proposed. There were drawbacks.

As described above, it has been very difficult to select a sealing material that satisfies the requirements of being heat-sealable to various containers at low temperatures, having good peeling feeling, and having good cold resistance.

In particular, for containers or sheets made of PET resin, there were no compositions containing ethylene-based copolymers as a main component that satisfied the adhesive strength and peeling feeling.

JP-A-10-147672

Therefore, the present inventors have investigated a polymer composition that can serve as an excellent easy-open sealing material for various materials. As a result, we have found that a polymer composition comprising a specific ethylene copolymer, a specific tackifying resin, a polybutene resin and/or an ethylene/α-olefin copolymer rubber as components can achieve such objects. We have arrived at the present invention. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a novel resin composition suitable as an easy-open sealing material.

The present invention comprises an ethylene/α-olefin copolymer (A) having a density of 880 to 920 kg/m ³ and a melt flow rate of 1 to 100 g/10 min. % by weight, polybutene resin with a melt flow rate of 0.5 to 3 g/10 min 5 to 30 wt %, polybutene resin (C) with a melt flow rate of 0.1 to 20 g/10 min and/or ethylene/α-olefin The present invention relates to a resin composition containing 5 to 30% by weight of a copolymer rubber (D) and having a melt flow rate of 1 to 100 g/10 minutes, and a sealing material comprising the same.

INDUSTRIAL APPLICABILITY The sealing material of the present invention can be heat-sealed to various containers at a low temperature, has good peeling feeling, and has physical properties such as good cold resistance, and can be used as an easy-open sealing material.

The ethylene/α-olefin copolymer (A) used in the present invention has a density of 880 to 920 kg/m ³ and a melt flow rate of 1 to 100 g/10 min, preferably 1 to 50 g/10 min. - is an olefin copolymer. The α-olefin to be copolymerized with ethylene preferably has 3 to 20 carbon atoms, such as 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-pentene, octadecene and the like. Among these α-olefins, 1-hexene, 1-octene, 1-heptene and 4-methyl-1-pentene are preferably used.

If the density is higher than the above range, the low-temperature sealability is poor, and if the density is lower than the above range, the heat resistance is poor and stickiness and blocking are likely to occur. If the melt flow rate is out of the above range, the workability is lowered and stable production cannot be performed.

The ethylene/α-olefin copolymer is not particularly limited, but includes those polymerized in the presence of a single-site catalyst or a multi-site catalyst such as a Ziegler-Natta catalyst. ethylene/α-olefin is preferred because of its excellent low-temperature sealability. Further, it is preferable to mix the ethylene/α-olefin polymerized by the single-site catalyst with the ethylene/α-olefin produced in the presence of the multi-site catalyst because the heat resistance is improved. Examples of α-olefins include α-olefins having about 3 to 8 carbon atoms such as propylene, 1-butene, 1-pentene, 1-hexene and 1-octene. Furthermore, for example, 1,4-hexadiene, 5-methyl-1,5-hexadiene, 1,4-octadiene, cyclohexadiene, cyclooctadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, 5-butylidene-2 Ternary or higher copolymers obtained by copolymerizing non-conjugated dienes such as -norbornene and 2-isopropenyl-5-norbornene may also be used.

Polybutene (C) is a homopolymer of 1-butene or copolymerized with 1-olefin other than 1-butene such as ethylene and propylene. It is preferable to contain polybutene because the knocking peeling at the time of opening is improved. The MFR of polybutene ranges from 0.1 to 20 g/10 min, preferably from 0.3 to 10 g/10 min, most preferably from 0.5 to 5 g/10 min. If the MFR is outside the range of 0.1 to 20 g/10 minutes, the appearance of peeling deteriorates, which is not preferable.

The ethylene/α-olefin copolymer rubber (D) consists of a copolymer of ethylene and α-olefin, and has a density of less than 880 kg/m ³ , preferably 850 to 879 kg/m ³ . Examples thereof include α-olefins having about 3 to 8 carbon atoms such as propylene, 1-butene, 1-pentene, 1-hexene and 1-octene. Furthermore, for example, 1,4-hexadiene, 5-methyl-1,5-hexadiene, 1,4-octadiene, cyclohexadiene, cyclooctadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, 5-butylidene-2 Ternary or higher copolymers obtained by copolymerizing non-conjugated dienes such as -norbornene and 2-isopropenyl-5-norbornene may also be used. The α-olefin content is preferably 5 to 70% by weight, particularly preferably 10 to 60% by weight. Specific examples include ethylene-propylene copolymers, ethylene-1-butene copolymers, Examples include ethylene-propylene-1,4-hexadiene copolymer, ethylene-propylene-dicyclopentadiene copolymer, ethylene-propylene-5-ethylidene-2-norbornene copolymer and the like. The inclusion of ethylene/α-olefin copolymer rubber is preferable because it can improve knocking peeling at the time of opening and improve low-temperature adhesion. The MFR of the ethylene/α-olefin copolymer rubber is preferably 0.5 to 10 g/10 min because of its high effect of suppressing knocking and flaking.

The tackifying resin (B) that can be used in the present invention is not particularly limited, but aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, aromatic hydrocarbon resins, polyterpene resins, rosins, Those used in the field of ordinary hot-melt adhesives, such as styrene resins, can be mentioned. Polyterpene resins, which are effective in improving adhesive strength to polyester resins, are particularly desirable. Examples of polyterpene resins include homopolymers and copolymers of α-pinene, β-pinene and dipentene, hydrogenated terpene resins obtained by hydrogenating these, and terpene-phenol resins. One or more of these polyterpene resins can be used, and polymers of α-pinene and β-pinene are preferred from the viewpoint of adhesiveness. The copolymerization ratio of the polymer is not particularly specified. The softening temperature of the polyterpene resin is desirably 90° C. to 140° C. in terms of adhesion and blocking properties.

In the resin composition of the present invention, the ethylene/α-olefin copolymer (A) is 40 to 90% by weight, preferably 50 to 80% by weight, and the tackifier resin (B) is 5 to 30 parts by weight, preferably 10% by weight. up to 20 parts by weight, and the total amount of polybutene resin (C) and/or ethylene/α-olefin copolymer rubber (D) is 5-30% by weight, preferably 10-25% by weight. When the polybutene resin (C) is added, it is preferable that the compounding ratio is 5 to 30% by weight, because the effect of improving the knocking peeling and the formability of films and the like are excellent. When the ethylene/α-olefin copolymer rubber (D) is added, the compounding ratio is preferably 5 to 30% by weight, since the anti-knocking peeling effect is high.

If necessary, the resin composition of the present invention may contain additives such as antioxidants, neutralizers, antiblocking agents, surfactants, slip agents, and the like, which are commonly used for polyolefins. In addition, other thermoplastic resins such as polyolefin may be added as long as the effects of the present invention are not impaired.
The resin composition of the present invention can be produced by a commonly used resin mixing apparatus. Examples thereof include single-screw extruders, twin-screw extruders, Banbury mixers, pressure kneaders, melt-kneading devices such as rotary rolls, Henschel mixers, V-blenders, ribbon blenders, and tumblers. When a melt-kneading apparatus is used, the melting temperature is preferably from the melting point of the ethylene/α-olefin copolymer to about 350°C.

The sealing material of the present invention comprises the above resin composition.

The sealing material of the present invention can be used as an easy-open sealing material for various materials. When used as an easy-open sealing material, it is often used in the form of being laminated on a substrate. As the base material, various materials such as paper, aluminum, polyester, polyethylene, polypropylene, aluminum deposited film, silica deposited film, etc. can be used. The substrate need not be a single layer, and may be a laminate of two or more layers.

In order to laminate the sealing material of the present invention on a substrate, a single layer or a coextruded film with low-density polyethylene or the like is prepared in advance from the sealing material by a casting method or an inflation method, and the film is laminated to the substrate by a dry lamination method. A method of extrusion laminating an outer sealing material onto the low density polyethylene surface of a multi-layer substrate obtained by applying an anchor coating agent to the substrate and extrusion laminating a low density polyethylene thereon, and applying the sealing material directly onto the substrate. A method of extrusion coating, a method of laminating an adhesive layer by sandwich lamination using polyethylene or the like as an adhesive layer, co-extrusion of the substrate and the composition, and the like can be employed.

When the sealing material of the present invention is used, examples of materials to be sealed include containers and sheets using polypropylene, polystyrene, impact-resistant polystyrene, polyesters such as polyethylene terephthalate, polycarbonate, polyvinyl chloride, and the like. However, polyester is most preferred because of its excellent sealing strength and transparency. Such materials may be in the form of foams. Typical of these materials are containers of various shapes, and the sealing material of the present invention can be used as an easily peelable sealant for container lids.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Preparation of sealing material Raw materials (A), (B), (C) and/or (D) are put into a tumbler in advance, mixed uniformly for 10 minutes, and then resin is produced using a twin-screw kneading extruder (screw diameter 30 mmφ). The mixture was melt-kneaded at a temperature of 180° C., extruded into a rod shape, and cut into pellets.

Preparation of Laminate An anchor coating agent (urethane-based AC agent) was applied to a biaxially stretched polyester film (thickness of 12 μm), and low-density polyethylene (MFR: 8 g/10 min, density: 919 kg/m ³ ) was applied thereon. A laminated base material was prepared by extrusion lamination at a resin temperature of 310° C. and a thickness of 25 μm.

The sealing material of the present invention was subjected to extrusion lamination on the laminated base material at a resin temperature of 240° C. to a thickness of 20 μm to prepare a composition for evaluation.

[Adhesion performance evaluation]
The sealing material surface of the evaluation structure was superimposed on a PP sheet (thickness 0.35 mm) and an A-PET sheet (thickness 0.3 mm), and bonded with a heat sealer to prepare a sample for measuring seal strength.

Sealing conditions: sealing pressure 0.2 MPa, sealing time 1.0 seconds, sealing temperature 100-180°C
A seal strength measurement sample was cut into a width of 15 mm perpendicular to the sealing direction, and the peel strength was measured with a tensile tester. A sealing material having a peel strength of 15 N/15 mm or more at 160° C. was judged to have good adhesion.

Peel strength measurement conditions: peel angle of 180 degrees, peel speed of 300 mm/min [determination of the presence or absence of knocking peel]
The chart at the time of peel strength measurement was checked, and knocking peeling was determined to have occurred when the maximum value of the difference between adjacent strength peaks of fluctuating peel strength was 1 N/15 mm or more.
[Low temperature adhesion]
A sample having an adhesive strength of 5 N/15 mm or more at a heat sealing temperature of 120° C. was considered to have good low-temperature adhesiveness.
[cold resistance]
The sample for seal strength measurement used for adhesion evaluation was placed at 4° C. for 1 hour, and the peel strength was measured within 1 minute after taking it out. Those having a peel strength of 10 N/15 mm or more were evaluated as good.

[Example 1]
As the ethylene/α-olefin copolymer (A), an ultra-low density polyethylene (Lumitac BL600K manufactured by Tosoh Corporation), which is an ethylene/butene copolymer produced by a single-site catalyst, has a density of 898 kg/m ³ and an MFR of 21 g/10 min. , hereinafter referred to as PE-1) is 65% by weight, and terpene-based tackifier (a copolymer of α-pinene and β-pinene, softening point 115 ° C., hereinafter referred to as TK-1) as a tackifier (B) is 15%. Using 20% by weight of polybutene (hereinafter referred to as PB-1) having an MFR of 1 g/10 minutes as the polybutene resin (C), a pellet-like sealing material was produced with a twin-screw extruder. Adhesion performance, presence or absence of knocking peeling, and low-temperature adhesion were evaluated, and the results are shown in Table 1.

[ Reference example 1 ]
Instead of PB-1 described in [Example 1], the ethylene/α ^- olefin copolymer rubber (D) is an ethylene-propylene copolymer (hereinafter referred to as EPR -1) was used, and the results are shown in Table 1.

[Example 3]
Instead of PB-1 described in [Example 1], 15% by weight of PB-1 and 5% by weight of EPR-1 used in [Example 2] were evaluated in the same manner, and the results are shown. 1.

[Example 4]
In place of PB-1 described in [Example 1], polybutene (hereinafter referred to as PB-2) with an MFR of 20 g/10 minutes was used, and evaluation was performed in the same manner, and the results are shown in Table 1.

[Example 5]
35% by weight of PE-1 described in [Example 1] and an ethylene-butene copolymer (density 905 kg/m ³ , MFR 8 g/10 min, hereinafter referred to as PE-2) produced by a multisite catalyst. Evaluation was performed in the same manner except that 30% by weight was used as the ethylene/α-olefin copolymer (A), and the results are shown in Table 2.

[Example 6]
35% by weight of PE-1 described in [Example 1] and an ethylene-butene copolymer produced by a multisite catalyst (density 910 kg/m ³ , MFR 20 g/10 min, hereinafter referred to as PE-3) Evaluation was performed in the same manner except that 30% by weight was used as the ethylene/α-olefin copolymer (A), and the results are shown in Table 2.

[Example 7]
30% by weight of PE-1 described in [Example 5], 20% of TK-1, and 10% by weight of PB-1 and 10% by weight of EPR-1 were used instead of PB-1. and the results are shown in Table-2.

[Comparative Example 1]
Instead of PE-1 described in [Example 1], an ethylene-butene copolymer (density 925 kg/m ³ , MFR 8 g/10 min, hereinafter referred to as PE-4) produced by a multisite catalyst was used. Others were evaluated in the same manner as [Example 1]. Table 3 shows the results.

[Comparative Example 2]
Evaluation was performed in the same manner except that PB-1 described in [Example 2] was not used, and 85% by weight of PE-1 and 15% by weight of TK-1 were used. Table 3 shows the results.

[Comparative Example 3]
TK-1 and PB-1 described in [Example 3] were not used, and 70% by weight of ethylene/α-olefin copolymer (A) and 30% by weight of EPR-1 were used. evaluated to Table 3 shows the results.

Claims (3)

40 to 90% by weight of an ethylene/α-olefin copolymer (A) having a density of 880 to 920 kg/m ³ and a melt flow rate of 1 to 100 g/10 min;
5 to 30% by weight of tackifying resin (B),
Polybutene resin (C) with a melt flow rate of 0.1 to 20 g/10 minutes 5 to 30% by weight
(A total of (A), (B), and (C) is 100% by weight), the resin composition has a melt flow rate of 1 to 100 g/10 min, and the adherend is made of a polypropylene or polyester resin. A sealing material characterized by being a container or a sheet . 40 to 90% by weight of an ethylene/α-olefin copolymer (A) having a density of 880 to 920 kg/m ³ and a melt flow rate of 1 to 100 g/10 min;
5 to 30% by weight of tackifying resin (B),
Polybutene resin (C) having a melt flow rate of 0.1 to 20 g/10 min and ethylene/α-olefin copolymer rubber (D) having a density of less than 880 kg/m ³ in a total amount of 5 to 30% by weight.
(The total of (A), (B), (C) and (D) is 100% by weight) and is made of a resin composition having a melt flow rate of 1 to 100 g / 10 minutes, and the adherend is polypropylene or A sealing material characterized by being a container or a sheet made of a polyester resin . The tackifying resin (B) according to claim 1 or 2 is a resin composition characterized by being a terpene resin having a softening point of 100 ° C. to 140 ° C., and the adherend is a polypropylene or polyester resin. A sealing material characterized by being a container or a sheet .