WO2015115631A1

WO2015115631A1 - Multi-layer non-oriented polyolefin film

Info

Publication number: WO2015115631A1
Application number: PCT/JP2015/052786
Authority: WO
Inventors: 直彦倉本; 三輪　和弘; 健二勘田; 陽介村越; 佐藤　豪一
Original assignee: サン・トックス株式会社
Priority date: 2014-01-29
Filing date: 2015-01-26
Publication date: 2015-08-06
Also published as: CN105848896B; CN105848896A; TWI613080B; JP6281950B2; KR20160114603A; TW201538326A; JP2015163461A

Abstract

　Provided is a multi-layer non-oriented polyolefin film having a high fusion-sealing strength and minimal variation therein, outstanding optical properties such as haze, luster and image sharpness, and exhibiting an excellent anti-static effect, even with a minimal quantity of anti-static agent contained.　This multilayer non-oriented polyolefin film comprises a layer A which is the outermost layer, a layer B which is an intermediate layer, and a layer C which is the outermost layer, laminated in that order, and characterized in that layer A and layer C are respectively formed from a polypropylene resin containing a propylene-ethylene random copolymer obtained by polymerization using a metallocene catalyst; layer B is formed from a polyolefin resin containing long-chain branched LLDPE, LLDPE, polypropylene resin and an anti-static agent, and that the film is used in fusion-sealing applications.

Description

Polyolefin-based unstretched multilayer film

The present invention relates to a polyolefin-based unstretched multilayer film used for fusing sealing. More specifically, the present invention relates to a polyolefin-based unstretched multilayer film that has a strong fusing seal strength, little variation, excellent optical characteristics and antistatic effects, and is suitably used for fusing seal applications.

Polyolefin film is widely used as a material for packaging various products.
Although various forms are known as a form of packaging, bag-shaped packaging materials are frequently used. As a technique for processing a packaging material into a bag shape, a bag making method using a fusing seal is widely used. Bag making by fusing sealing is a method in which, for example, the ends of two films or two folded films are cut simultaneously with a heated fusing blade and simultaneously welded to form a bag.
The polyolefin film to which the fusing seal is applied is a non-stretched polyolefin because there is little difference in the fusing seal strength between the MD direction and the TD direction, and a constant fusing seal strength can be obtained even if the fusing seal is performed in any direction. System films are widely used.
In the past, it has been pointed out that an unstretched polyolefin film is inferior in film strength, for example, when compared with, for example, a biaxially stretched polyolefin film. However, attempts have been made to overcome the above-mentioned drawbacks by multilayering the film (see JP-A-2-141238 and JP-A-62-44447). JP-A-2-141238 relates to a multilayer film comprising three layers including a blend layer of polyethylene and propylene resin;
JP-A-62-44447 relates to a multilayer film composed of three layers of propylene resins having different compositions. However, according to the technique of Japanese Patent Laid-Open No. 2-141238, it is pointed out that problems such as blocking between films and whitening of the film due to aging occur, although a certain improvement in strength is observed.
According to the technique of JP-A-62-44447, when a bag is made after corona discharge treatment for the purpose of improving printability, there is a problem that the fusing seal strength at the opening of the bag is inferior. Improvement is also required.
By the way, since the polyolefin-based film has a property of generating static electricity by friction and peeling, it is widely practiced to add an antistatic agent to the film in order to prevent static electricity.

When an unstretched polyolefin-based multilayer film is applied to a fusing seal, it has been found that there are the following difficulties.
(1) Inferior optical properties such as transparency, haze, image clarity (image clarity),
(2) Fusing seal strength is insufficient,
(3) When an antistatic agent is blended, a processing machine such as a roll is soiled, and the processed product after the wrinkle is contaminated.
The present invention has been made in order to overcome the above situation.
Therefore, the object of the present invention is to maintain the advantage of the polyolefin-based unstretched film that there is little difference in the fusing seal strength between the MD direction and the TD direction, while being excellent in optical characteristics and fusing seal strength, and to reduce the blend amount of the antistatic agent An object of the present invention is to provide a polyolefin-based unstretched film that can exhibit an excellent antistatic effect even in a small amount and can be suitably applied to a fusing seal.
According to the present invention, the above objects and advantages of the present invention are:
A polyolefin-based unstretched multilayer film in which an outermost layer A layer, an intermediate layer B layer and an outermost layer C layer are laminated in this order,
Each of the A layer and the C layer is formed from a polypropylene resin containing 50% by weight or more of a propylene-ethylene random copolymer polymerized using a metallocene catalyst,
B layer
Long chain branched LLDPE 15-75 wt%,
25 to 85% by weight of LLDPE (excluding the above-mentioned long chain branched LLDPE), and 30% by weight or less of the propylene propylene resin, provided that the total of the long chain branched LLDPE, LLDPE and polypropylene resin is 100% by weight As well as a polyolefin-based resin containing an antistatic agent,
The long chain branched LLDPE has the following conditions (1) to (3):
(1) The ratio Mw / Mn of the weight average molecular weight Mw in terms of polystyrene and the number average molecular weight Mn measured by gel permeation chromatography is 7.5 to 15.0.
(2) The amount of amorphous components measured by the temperature rising elution fractionation method is 1 to 4% by weight.
And (3) The number of branches having 8 or more carbon atoms measured by ¹³ C-NMR is 1.5 to 5.0 per 1,000 carbon atoms.
Is achieved by the multilayer film, characterized in that it is used for fusing and sealing applications.

The polyolefin-based multilayer film of the present invention is a multilayer film in which an outermost layer A layer, an intermediate layer B layer and an outermost layer C layer are laminated in this order.
<A layer and C layer>
In the polyolefin multilayer film of the present invention, the outermost layers A and C are each formed from a polypropylene resin containing 50 wt% or more of a propylene-ethylene random copolymer polymerized using a metallocene catalyst. Is done. The A layer and the C layer may be composed of only a propylene-ethylene random copolymer (metallocene propylene-ethylene copolymer) polymerized using a metallocene catalyst, and the range is 50% by weight or less. If so, it may contain other resins.
The composition of the polypropylene resin for forming the A layer and the polypropylene resin for forming the C layer may be the same or different.
[Metalocene propylene-ethylene copolymer]
The metallocene propylene-ethylene copolymer is a random-type propylene-ethylene copolymer polymerized using a metallocene catalyst. The use of this metallocene-based propylene-ethylene copolymer is preferable in that the resulting multilayer film exhibits a high degree of blocking resistance and exhibits excellent optical properties when formed into a multilayer film.
The metallocene-based catalyst is a catalyst comprising a metallocene-type transition metal compound having at least one, preferably two, substituted or unsubstituted cyclopentadienyl ligands and a promoter. Examples of the cocatalyst include organoaluminum compounds; complexes of organoboron compounds and cations; ion-exchange silicates and the like, and one or more selected from these can be used. . The metallocene catalyst may be supported on a suitable inorganic substance. Metallocene catalysts are already known in the art, and those skilled in the art can appropriately select and use an appropriate metallocene catalyst according to the purpose.
The metallocene propylene-ethylene copolymer has a molecular weight distribution Mw / Mn represented by a ratio of a weight average molecular weight Mw in terms of polystyrene and a number average molecular weight Mn measured by gel permeation chromatography of 1.5 to 3. 5 is preferable. The value of Mw / Mn is more preferably 1.8 to 3.2, still more preferably 2.0 to 3.0. If Mw / Mn of the metallocene-based propylene-ethylene copolymer is less than 1.5, the melt tension becomes too low, so that the film forming property is inferior. On the other hand, it is preferable that Mw / Mn is 3.5 or less from the viewpoint of securing blocking resistance when a multilayer film is formed and securing optical properties in the multilayer film and the composite film. The metallocene propylene-ethylene copolymer preferably has a Mw of 450,000 to 100,000, more preferably 400,000 to 200,000.
The metallocene propylene-ethylene copolymer preferably has a melt flow rate MFR of 1 to 30 g / 10 minutes measured at 230 ° C. under a load of 2.16 kg in accordance with JIS K 7210. This value is more preferably 5 to 15 g / 10 min. When the MFR is less than 1 g / 10 minutes, the melt viscosity is too high, and thus the pressure in the film forming machine (for example, an extruder) becomes excessively high during the production of the multilayer film, and the productivity may decrease. Further, it may cause poor appearance such as non-uniform film thickness and melt fracture. On the other hand, if the MFR exceeds 30 g / 10 min, the outer layer may have a non-uniform film thickness due to an excessive difference in melt viscosity with the intermediate layer resin. In addition to this, the blocking resistance when a multilayer film is formed may be impaired.
The metallocene propylene-ethylene copolymer preferably has a melting point of 120 to 145 ° C, more preferably 120 to 140 ° C, and still more preferably 120 to 135 ° C. A metallocene propylene-ethylene copolymer exhibiting a melting point at a temperature within this range is preferred in that it provides an excellent balance between heat resistance when producing a multilayer film and transparency when formed into a multilayer film. The melting point refers to the peak top temperature (Tm) of the maximum endothermic peak in the differential scanning calorimeter (DSC) chart (the same applies hereinafter).
The content ratio of ethylene units in the metallocene propylene-ethylene copolymer is preferably 1 to 10 mol%, more preferably 2 to 5 mol%. By setting the content ratio of the ethylene unit within this range, the resulting multilayer film can exhibit excellent blocking resistance without impairing transparency, which is preferable.
[Other resins]
Other resins that can be used with the metallocene propylene-ethylene copolymer as described above to form the A layer and the C layer of the polyolefin-based multilayer film of the present invention include, for example, a metallocene propylene-ethylene copolymer. Mention may be made of polypropylene resins other than polymers (polypropylene resin (a)). The polypropylene resin (a) preferably has a melting point in the range of 120 to 170 ° C., and has a melt flow rate MFR of 1 to 30 g measured at 230 ° C. and a load of 2.16 kg in accordance with JIS K 7210. It is preferably in the range of / 10 minutes.
Examples of the polypropylene resin (a) include a homopolymer of propylene and a copolymer of propylene and a copolymer component. As the copolymer component, for example, ethylene and α-olefin are preferable, and specifically, for example, ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene. 4-methyl-1-pentene can be used, and one or more selected from these can be used. The proportion of the copolymer component in this polypropylene resin is preferably 10 mol% or less, more preferably 5 mol% or less, and even more preferably 3 mol% or less.
[Optional ingredients]
The polypropylene resin for forming the A layer and the C layer of the polyolefin multilayer film of the present invention contains the metallocene propylene-ethylene copolymer as an essential resin, and optionally includes a polypropylene resin (a). In addition to these, as long as they do not inhibit the effects of the present invention, those generally used as additives for resins may be further contained as optional additives. Examples of such optional additives include heat stabilizers, processing stabilizers, lubricants, nucleating agents, antifogging agents, antiblocking agents, antioxidants, ultraviolet absorbers, and pigments.
These optional additives may be added by a method of directly blending with any of the resins constituting the polypropylene resin for forming the A layer and the C layer, or a master containing these additives in a high concentration. You may add by the method of mix | blending as a batch. As the base resin for the masterbatch, the metallocene propylene-ethylene copolymer and the polypropylene resin (a) when used can be used.
[Use ratio of each component in polypropylene resin for forming A layer and C layer]
The layers A and C of the polyolefin-based multilayer film of the present invention are made of a polypropylene resin containing 50% by weight or more of the metallocene propylene-ethylene copolymer as described above, where the total of polypropylene resins is 100% by weight. It is formed. By using a polypropylene resin containing a metallocene propylene-ethylene copolymer at such a ratio, excellent transparency, excellent image clarity, etc. can be ensured in the resulting multilayer film. This value is preferably 55 to 95% by weight, more preferably 60 to 90% by weight.
The polypropylene resin for forming the A layer and the C layer of the polyolefin multilayer film of the present invention comprises only the metallocene propylene-ethylene copolymer and the polypropylene resin (a), and other types of resins are used. It is preferable not to contain.
The content of the optional additive in the polypropylene resin for forming the A layer and the C layer is preferably 5 parts by weight or less with respect to 100 parts by weight in total of the polypropylene resin, and 3 parts by weight or less. Preferably there is. However, it is preferable that the polypropylene resin for forming the A layer and the C layer does not contain an antistatic agent.
<B layer>
B layer which is an intermediate layer of the polyolefin-based multilayer film of the present invention,
Long chain branched LLDPE 15-75 wt%,
LLDPE (excluding the above-mentioned long-chain branched LLDPE) is 25 to 85% by weight, and a polypropylene resin is 30% by weight or less, and a polyolefin resin containing an antistatic agent. Here, the total of the long-chain branched LLDPE, LLDPE and the polypropylene resin is 100% by weight.
[Long-chain branched LLDPE]
The long-chain branched LLDPE is a low-density polyethylene having a branch, and is common to LLDPE (linear low-density polyethylene, described later) and LDPE (low-density polyethylene) in the prior art. However, the long-chain branched LLDPE in the present invention differs from the LLDPE and LDPE in the prior art in at least Mw / Mn, the amount of non-crystalline components and the content of long-chain branches. That is, the long-chain branched LLDPE in the present invention satisfies all of the following conditions (1) to (3).
(1) The ratio Mw / Mn (molecular weight distribution) of polystyrene-equivalent weight average molecular weight Mw and number average molecular weight Mn measured by gel permeation chromatography is 7.5 to 15.0.
(2) The amount of amorphous components measured by the temperature rising elution fractionation method is 1 to 4% by weight.
And (3) The number of branches having 8 or more carbon atoms measured by ¹³ C-NMR is 1.5 to 5.0 per 1,000 carbon atoms.
The long-chain branched LLDPE in the present invention has a ratio Mw / Mn (molecular weight distribution) of a weight average molecular weight Mw and a number average molecular weight Mn in terms of polystyrene measured by gel permeation chromatography (GPC) of 7.5 to 15.0. It is. This value is preferably 8.5 to 14.5, and more preferably 9.5 to 13.5. By using LLDPE having such a molecular weight distribution, the multilayer film of the present invention exhibits an excellent antistatic effect even when the blending amount of the antistatic agent is small, and the multilayer film is fused. When sealing, it is possible to obtain an advantage that the fusing seal strength is high and the variation thereof is small.
The long-chain branched LLDPE in the present invention has a polystyrene-equivalent weight average molecular weight Mw measured by GPC of preferably 80,000 to 150,000, and more preferably 90,000 to 140,000.
The long-chain branched LLDPE in the present invention has an amorphous component amount of 1 to 4% by weight measured by a temperature rising elution fractionation method.
In the temperature rising elution fractionation method, a solution obtained by dissolving a polymer sample in a predetermined solvent at a high temperature is supplied to a TREF (Temperature Rising Elution Fractionation) column, and then cooled to precipitate and adsorb the polymer sample in the column. Then, the column temperature is gradually raised and the eluted fraction is analyzed. In the present invention, after the column after the sample is supplied is cooled to 0 ° C., the supply of the solvent is started, and the fraction eluted during the period in which the column temperature is maintained at 0 ° C. is used as an amorphous component. Is evaluated as the amount of non-crystalline component. The amount of the amorphous component of the long chain branched LLDPE is preferably 1.5 to 3.0% by weight.
Such a temperature rising elution fractionation method can be performed, for example, using an appropriate temperature rising elution fractionation (TREF) apparatus such as a special TREF apparatus manufactured by Senshu Kagaku Co., Ltd.
By using the long-chain branched LLDPE having the crystallinity as described above, it is possible to obtain the advantage of ensuring the blocking resistance and the back feeling (elasticity) of the multilayer film of the present invention.
In the long-chain branched LLDPE in the present invention, the number of branches having 8 or more carbon atoms measured by ¹³ C-NMR is 1.5 to 5.0 per 1,000 carbon atoms. This value is preferably 2.0 to 5.0, and more preferably 2.5 to 4.5. By using LLDPE having such a long chain branch, the multilayer film of the present invention can stably exhibit high fusing seal strength regardless of the surrounding environment (for example, temperature, humidity, etc.) at the fusing seal. This is preferable.
LLDPE in the prior art is dominant when the number of carbon atoms in the branch is 6 or less, and even if there are branches having 8 or more carbon atoms, the amount is small, usually 1 or less per 1,000 carbon atoms. And stays at most 2 or less.
On the other hand, LDPE has more than 5.0 branches per 10,000 carbon atoms in the measurement of ¹³ C-NMR.
Therefore, the long-chain branched LLDPE (B1) in the present invention can be distinguished from LLDPE and LDPE in the prior art by the amount of branching having 8 or more carbon atoms measured by ¹³ C-NMR.
The following describes how the content of the long chain branching of the long chain branching LLDPE in the present invention is measured. Here, C ₈ branch (1-decene structure) is considered as a branch of long chain branch LLDPE, and C ₆ branch (1-octene structure) is considered as a branch of LLDPE in the prior art.
Methylene carbon present in the main chain of polyethylene is observed at ¹³ C-NMR at a chemical shift δ = 30 ppm. Methyl carbon branched end are both of _{C 8} branched and _{C 6} branched, appearing at a chemical shift δ = 14.06ppm. However, second and third chemical shift of each methylene carbon of the branched end is in a C ₈ branched and C ₆ branched, than differs as in Table 1 below.

In the present invention, paying attention to the second methylene carbon from the branch end of these, whether or not the number of carbons in the branch is 8 or more is determined by the chemical shift.
In actual calculation, the relative value of the peak area appearing at the chemical shift δ = 22.87 ppm to the peak area appearing at the chemical shift δ = 30 ppm attributed to the methylene carbon of the main chain is evaluated.
The measurement of ¹³ C-NMR as described above can be performed under the following conditions using an appropriate nuclear magnetic resonance analyzer such as “JNM-ECS400” manufactured by JEOL Ltd.
Solvent: Mixed solvent of trichlorobenzene / heavy benzene (75/25% by volume)
Sample concentration: 80 mg / 2.5 mL solution Measurement mode: 1H-complete decoupling Measurement temperature: 120 ° C.
Pulse width: 90 degree pulse Pulse repetition time: 9 seconds Integration number: 9,000 times The content of long chain branching in the present invention is:
The peak area of the second carbon from the end of the C ₈ branch (chemical shift δ = 22.87 ppm) is
It is expressed as a relative value when the peak area of methylene carbon (chemical shift δ = 30 ppm) constituting the polymer chain is 1,000. The unit is (pieces / 1,000 C).
For reference, the various parameters described above are compared in Table 2 below for typical polyethylenes.

The long-chain branched LLDPE in the present invention as described above may be synthesized by any method as long as it satisfies the above requirements. For example, it can be produced by a method using a known Ziegler-Natta catalyst, preferably with an appropriate donor compound; a method using a Phillips catalyst; a method using a metallocene catalyst. Among these, the method using a metallocene catalyst is preferable in that a polymer having the above characteristics can be easily obtained. In this case, the same metallocene catalyst as described above for the metallocene catalyst for synthesizing the metallocene propylene-ethylene copolymer can be used.
[LLDPE]
The LLDPE is an LLDPE other than the above long-chain branched LLDPE, and it is sufficient to use the LLDPE in the prior art.
In order to distinguish this LLDPE from the above long-chain branched LLDPE, for example, the following parameters can be exemplified.
This LLDPE is preferably a copolymer of ethylene and an α-olefin other than ethylene. In this case, the α-olefin is preferably an α-olefin having 3 to 12 carbon atoms, specifically, for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1- Pentene, 1-decene, 1-dodecene and the like;
The polystyrene-equivalent molecular weight distribution Mw / Mn measured by GPC is preferably 1.5 to 5.0,
The amount of non-crystalline components measured by the temperature rising elution fractionation method is preferably 1 to 5% by weight, and the number of branches having 8 or more carbon atoms measured by ¹³ C-NMR is 1 per 1,000 carbon atoms. The number is preferably not more than 1, and more preferably not more than 2. The measurement method of these parameters is the same as in the case of long-chain branched LLDPE.
With respect to the LLDPE, the MFR measured at 190 ° C. and a load of 2.16 kg in accordance with JIS K 7210 is preferably 0.5 to 20 g / 10 min.
Such LLDPE can be obtained by a known method. For example, it can be synthesized by a chromium catalyst alone or a catalyst system using a chromium catalyst and a Ziegler-Natta catalyst in combination.
[Polypropylene resin]
Examples of the polypropylene resin include metallocene propylene-ethylene copolymers and polypropylene resins (a) used to form the A layer and the C layer, and one kind selected from these. The above can be preferably used.
[Other resins]
The polyolefin resin used for forming the layer B in the polyolefin multilayer film of the present invention contains the long chain branched LLDPE, LLDPE and polypropylene resin as described above, but within the range not impairing the effects of the present invention. In addition to these, other resins may be contained.
Examples of other resins that can be used here include polyethylene resins other than those described above.
It is preferable that the polyolefin resin used for forming the B layer in the multilayer film of the present invention does not contain other resins other than the long-chain branched LLDPE, LLDPE, and the polypropylene resin.
[Antistatic agent]
The polyolefin resin used for forming the B layer in the polyolefin multilayer film of the present invention contains an antistatic agent.
Examples of the antistatic agent used herein include ester compounds, amine compounds, amide compounds, fatty acids, aliphatic alcohols, and the like, and preferably one or more selected from these are preferably used. Can do.
The ester compound is preferably a fatty acid ester of glycerin, specifically, for example, glycerin monolaurate, glycerin monomyristate, glycerin monopalmitate, glycerin monostearate, glycerin monobehenate, glycerin monooleate, glycerin mono- Monoglycerol fatty acid esters such as dilaurate, glycerol mono-dipalmylate, glycerol mono-distearate, glycerol mono-dibehenate, glycerol mono-diolate, glycerol di-trioleate, glycerol di-tristearate;
Diglycerin fatty acid esters such as diglycerin laurate, diglyceryl stearate, diglycerin oleate, diglycerin caprylate;
Examples thereof include polyglycerin fatty acid esters such as tetraglycerin stearate, tetraglycerin oleate, hexaglycerin stearate, decaglycerin stearate, and the like, and one or more selected from these can be used.
Examples of the amine compounds include lauryl diethanolamine, myristyl diethanolamine, palmityl diethanolamine, stearyl diethanolamine, oleyl diethanolamine, linol diethanolamine, linolenic ethanolamine, stearol diethanolamine, stearyl diethanolamine monostearate, stearyl diethanolamine distearate, stearyl diethanolamine monomethylene. State, stearyl diethanolamine monopalmitate, palmityl diethanolamine monopalmitate, N, N-bis (2-hydroxyethyl) fatty amine, and the like can be used, and one or more selected from these can be used. it can.
Examples of the amide compounds include myristyl diethanolamide, palmityl diethanolamide, stearyl diethanolamide, oleyl diethanolamide, arachidyl diethanolamide, etc., and one or more selected from these may be used. Can do.
Examples of the fatty acid include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachin And acid, gadrenic acid, behenic acid, erucic acid, lignoceric acid, ceracoleic acid, serotic acid, montanic acid, melissic acid, celloplastic acid, ricinoleic acid, 12-hydroxystearin, and the like. One or more can be used. As the fatty acid, it is preferable to use a higher fatty acid having 14 to 20 carbon atoms.
Examples of the aliphatic alcohol include stearyl alcohol and oleyl alcohol, and one or more selected from these can be used.
As the antistatic agent in the present invention, it is preferable to use an ester compound and an amine compound of the above in combination,
Use only ester compounds and amine compounds, or ester compounds and amine compounds,
It is preferable to use a mixture of at least one selected from the group consisting of fatty acids and aliphatic alcohols.
The antistatic agent may be added by a method of directly blending with any of the resins constituting the polyolefin resin for forming the B layer, or may be blended as a master batch containing these additives in a high concentration. You may add by a method. As the base resin for the master batch, it is preferable to use one of the resins constituting the polyolefin resin.
[Optional ingredients]
The polyolefin-based resin for forming the B layer of the polyolefin-based multilayer film of the present invention is a range that does not impair the effects of the present invention. Furthermore, you may contain. Examples of such optional additives include heat stabilizers, processing stabilizers, lubricants, nucleating agents, antifogging agents, antiblocking agents, antioxidants, ultraviolet absorbers, and pigments.
These optional additives may be added by a method of directly blending with any of the resins constituting the polypropylene resin for forming the B layer, or blended as a masterbatch containing these additives at a high concentration. You may add by the method of doing.
[Use ratio of each component in polyolefin resin for forming layer B]
The content of each resin in the polyolefin resin for forming the B layer of the polyolefin multilayer film of the present invention is as follows, with the total of the long chain branched LLDPE, LLDPE and polypropylene resin being 100% by weight. is there.
Long-chain branched LLDPE: 15 to 75% by weight, preferably 20 to 70% by weight
LLDPE: 25 to 85% by weight, preferably 30 to 80% by weight
Polypropylene resin: 30% by weight or less, preferably 20% by weight or less By setting the content of long-chain branched LLDPE and LLDPE in the above range, a multilayer film having an excellent balance between fusing seal strength and transparency can be obtained. it can.
The content of the antistatic agent in the polyolefin resin for forming the B layer is preferably 0.1 to 3.0 parts by weight with respect to a total of 100 parts by weight of the long-chain branched LLDPE, LLDPE and the polypropylene resin. Yes, more preferably 0.1 to 2.0 parts by weight, still more preferably 0.1 to 1.0 parts by weight.
In the present invention, the effect of adding an antistatic agent is great. That is, when compared with the prior art polyolefin film,
When the same amount of antistatic agent is blended, the resulting antistatic effect is greater,
A smaller amount of antistatic agent is sufficient to obtain the same level of antistatic effect. In the present invention, even when the amount of the antistatic agent in the polyolefin resin for forming the B layer is, for example, 0.7 parts by weight or less, preferably 0.6 parts by weight or less, a good antistatic effect can be obtained. Can do.
The content of the optional additive in the polyolefin-based resin for forming the B layer is preferably 5 parts by weight or less with respect to 100 parts by weight of the total of the long-chain branched LLDPE, LLDPE and the polypropylene-based resin. More preferably, it is at most parts.
<Thickness of each layer in polyolefin-based unstretched multilayer film>
The A to C layers in the polyolefin-based multilayer film of the present invention are each formed from the resin as described above.
The total thickness of the polyolefin-based multilayer film of the present invention is preferably 20 to 200 μm, and more preferably 30 to 150 μm, from the viewpoints of practicality as a package and suitability for a fusing sealer.
The ratio of the thickness of the B layer to the total thickness of the polyolefin-based multilayer film of the present invention is preferably 30 to 80% from the viewpoint of the balance between physical properties such as impact resistance and optical properties, and is preferably 33 to 70%. % Is more preferable.
<Method for producing polyolefin-based unstretched multilayer film>
The polyolefin-based unstretched multilayer film of the present invention can be produced by any method as long as the method does not substantially involve stretching. Here, “substantially without stretching” does not mean that even a slight orientation occurs in the film manufacturing process, but means that the film does not go through an explicit stretching process. To do. Therefore, for example, when an extrusion process under the conditions normally employed is employed, it is allowed that some orientation occurs in the extrusion direction.
As a method for producing the multilayer film of the present invention, an appropriate method such as an extrusion method or a casting method can be employed. Since all the resins constituting each layer of the multilayer film of the present invention have an appropriate MFR and are highly compatible with a melt-type film forming machine, it is possible to adopt the extrusion method of the above. This is preferable in that the effect can be maximized. As the die for the extrusion method, a T die, an annular die, or the like can be used. However, from the viewpoint of precisely controlling the thickness of the layer to obtain excellent optical characteristics, it is not preferable to use an annular die, and it is preferable to use a T die or the like.
The multilayer film of the present invention has a multilayer structure composed of three layers A to C. As a method for multilayering the film, a known method such as a co-extrusion method or an in-line laminating method can be employed. Examples of the coextrusion method include a multi-manifold method and a feed block method. Of these, the coextrusion method is preferably used because the thickness of each layer can be controlled uniformly in the width direction.
The multilayer film of the present invention is scheduled to be melt-sealed and applied as a melt-sealed bag. Therefore, printing may be performed on the outermost layer surface in order to clearly indicate the origin of the product or to develop a design effect. In such a case, surface treatment may be performed inline or offline on the outermost layer surface (the surface of the A layer or the C layer) for the purpose of improving the affinity or adhesion with the printing ink. Examples of the surface treatment include corona discharge treatment and flame (flame) treatment.
<Fusing seal bag>
Using the polyolefin-based unstretched multilayer film as described above, a fusing seal bag can be produced.
A fusing seal bag can be manufactured by a well-known method using a commercially available side welder (fusing machine). The fusing conditions recommended when producing a fusing seal bag using the multilayer film of the present invention are, for example, as follows.
Seal blade temperature: 260 ~ 360 ℃
Bag making speed: 60-180 shots / minute

Hereinafter, the present invention will be described with reference to examples and comparative examples, but the present invention is not limited to these examples.
Each evaluation in the following examples and comparative examples was performed on both the multilayer film that had not been subjected to the double-sided corona treatment and the multilayer film that had been subjected to the single-sided corona treatment by the following procedure.
<Evaluation of multilayer film>
(1) Haze As a transparency index, a haze meter (model number: NDH5000) manufactured by Nippon Denshoku Industries Co., Ltd. was used, and haze was measured based on JIS K7136.
(2) Glossiness Glossiness was measured according to JIS K 7105 using a gloss meter (model number: UGV-5D) manufactured by Suga Test Instruments Co., Ltd. as an index of glossiness. The glossiness was evaluated for both the A layer side surface and the C layer side surface of the multilayer film.
(3) Image sharpness As an index of image clarity, Suga Test Instruments Co., Ltd., image clarity measuring instrument (model number: ICM-1DP) is used, and the slit width of the optical comb is defined according to JIS K 7105. The image definition was measured at 0.125 mm.
(4) Surface resistivity The surface resistivity was measured for the A layer surface and the C layer surface using a high resistance meter (model number: HP4339B) manufactured by Nippon Hewlett-Packard Co., Ltd. The test piece size was 120 mm × 120 mm, and the resistance value after applying a DC voltage of 500 V for 2 minutes was measured.
The evaluation results of Table 4, "nE + m" indicates that the surface resistivity is "n × 10 ^m Ω". For example, “8E + 11” indicates that the surface specific resistance value was “8 × 10 ¹¹ Ω”.
(5) Fusing seal strength Using a fusing seal machine (model number: PP504AC, seal width 300 mm) manufactured by Kyoei Co., Ltd., bag making is performed at a seal blade temperature of 320 ° C. and a speed of 120 shots / min. Got. A sample was cut out in a strip shape having a length in the direction perpendicular to the sealing direction of 150 mm and a width of 15 mm from the obtained fusing seal bag. Here, the sample was cut out so that the fusing seal portion was located at the end of the strip shape.
About this strip sample, it opened 180 degree | times so that a fusing seal part may be located in the center, both ends were pinched | interposed into the chuck | zipper, and the tension test was done so that a fusing seal part might peel. As the tensile tester, Shimadzu Corporation model number: AG500 was used, the test was conducted at a tensile speed of 100 mm / min, and the strength when the fusing seal part broke was determined as fusing seal strength (unit: N / 15 mm). It was.
According to the above procedure, 30 fusing seal bags were measured, and the maximum value, minimum value, and variation (difference between the maximum value and the minimum value) were examined.
Example 1
<Manufacture of multilayer film>
From a total of three extruders, one single-screw extruder with a screw diameter of 75 mm for the intermediate layer (B layer) and two single-screw extruders with a screw diameter of 50 mm for both outer layers (A layer and C layer) Resin was supplied to each extruder as follows using the three-type three-layer T-die film forming apparatus.
Extruder for layer A; PP-1 (manufactured by Nippon Polypro Co., Ltd., product number: WFX4TA, melting point = 126 ° C., MFR = 7.0 g / 10 min (230 ° C.), Mw / Mn = 3.0) 70 parts by weight And PP-2 (manufactured by Nippon Polypro Co., Ltd., product number: FW3GT, melting point = 148 ° C., MFR = 7.0 g / 10 min (230 ° C.), Mw / Mn = 5.3) 30 parts by weight for layer B Extruder; b-LLDPE-1 (manufactured by Sumitomo Chemical Co., Ltd., product number: CU7004, melting point = 108 ° C., MFR = 3.0 g / 10 min (190 ° C.), Mw / Mn = 11.9, density = 0.0.0. 924 g / cm ³ , amorphous component = 2.5% by weight, long chain branch content = 4.12 / 1,000 C) and LLDPE-1 (Ube Maruzen Polyethylene Co., Ltd., product number: 2040FC) Melting point = 118 ° C., MFR = 3.7 g / 10 (190 ℃), Mw / Mn = 5.0, density = 0.919 g / cm ^3, a non-crystalline component = 0.6% by weight, the long-chain branch content = 1.31 pieces / 1,000C) 50 Weight Mixer in which 5 parts by weight of antistatic agent masterbatch MB-A is blended with respect to 100 parts by weight of the total part C-layer extruder; PP-1 (manufactured by Nippon Polypro Co., Ltd., product number: WFX4TA, melting point = 126 C, MFR = 7.0 g / 10 min (230 ° C.), 70 parts by weight of Mw / Mn = 3.0 and PP-2 (manufactured by Nippon Polypro Co., Ltd., product number: FW3GT, melting point = 148 ° C., MFR = 7 0.0 g / 10 min (230 ° C.), Mw / Mn = 5.3) 30 parts by weight of mixture For all the above three extruders, the resin temperature was 220 ° C., the residence time was 1 min, and the T-die temperature was 230 ° C. Extruded from each T-die, and 3 layers were combined and cooled at 25 ° C To obtain a multi-layer film through a roll. This multilayer film had a three-layer structure, the total thickness was 50 μm, and the three-layer thickness structure was an A layer of about 10 μm, a B layer of about 30 μm, and a C layer of about 10 μm. The multilayer film in this state was aged at 40 ° C. for 24 hours to obtain a multilayer film that had not been subjected to double-sided corona treatment.
The multilayer film obtained above was subjected to corona discharge treatment so that the wetting index of the surface on the A layer side of the multilayer film obtained was 42 mN / m, and further aged for 24 hours at 40 ° C. A film was obtained.
The evaluations (1) to (5) were performed using these two types of multilayer films. The evaluation results are shown in Table 4.
Examples 2 to 16 and Comparative Examples 1 to 15
In Example 1 above, a multilayer film was produced in the same manner as in Example 1 except that the type and amount of resin supplied to the extruder for each layer and the thickness of each layer were as shown in Table 3. And evaluated each.
The evaluation results are shown in Table 4.
In addition, the abbreviation of each component in the said Table 3 has the following meaning, respectively.
<Raw resin>
b-LLDPE-1; manufactured by Sumitomo Chemical Co., Ltd., product number: CU7004
b-LLDPE-2; manufactured by Sumitomo Chemical Co., Ltd., product number: GT140
b-LLDPE-3; manufactured by Sumitomo Chemical Co., Ltd., product number: GH051
LLDPE-1; manufactured by Ube Maruzen Polyethylene Co., Ltd., product number: 2040FC
LLDPE-2; manufactured by Ube Maruzen Polyethylene Co., Ltd., product number: 1540F
PP-1; manufactured by Nippon Polypro Co., Ltd., product number: WFX4TA (propylene-ethylene random copolymer polymerized using a metallocene catalyst)
PP-2; manufactured by Nippon Polypro Co., Ltd., product number: FW3GT
<Antistatic agent>
A: Mixture of glycerin fatty acid ester and stearyl diethanolamine B: Mixture of glycerin fatty acid ester, diethanolamine stearate and stearyl alcohol C: Mixture of glycerin fatty acid ester, N, N bis (2-hydroxyethyl) fatty amine and higher fatty acid All of the inhibitors are LLDPE-1 (manufactured by Ube Maruzen Polyethylene Co., Ltd., product number: 2040FC, melting point = 118 ° C., MFR = 3.7 g / 10 min (190 ° C.), Mw / Mn = 5 as a base resin. 0.0, density = 0.919 g / cm ³ , non-crystalline component = 0.6% by weight, long chain branching content = 1.31) 10 parts by weight of antistatic agent were mixed with 90 parts by weight. Formulated as a pelletized masterbatch.
Each resin supplied to the extruder is a resin having the characteristics shown in Table 5 below.
The content of long chain branches shown in the “long chain branch” column is the number of carbon atoms per 1,000 carbon atoms, calculated according to the following formula (1) from the results of ¹³ C-NMR measured under the following conditions: The number of branches of 8 or more.
[ ^13C -NMR measurement conditions]
Measuring device: Model “JNM-ECS400” manufactured by JEOL Ltd.
Solvent: Mixed solvent of trichlorobenzene / heavy benzene (75/25% by volume)
Sample concentration: 80 mg / 2.5 mL solution Measurement mode: 1H-complete decoupling Measurement temperature: 120 ° C.
Pulse width: 90 degree pulse Pulse repetition time: 9 seconds Integration number: 9,000 times Long chain branch content (pieces / 1000C) = A ÷ B × 1,000 (1)
(In Formula (1), A is a peak area of chemical shift δ = 22.87 ppm, and B is a peak area of chemical shift δ = 30 ppm.)
In the temperature rising elution fractionation method under the following conditions, the amorphous component content is measured during the period in which the column supply after the sample supply is cooled to 0 ° C. and then the supply of the solvent is started and the column temperature is maintained at 0 ° C. This is the weight ratio of the fraction eluted in the total fraction.
[Conditions for temperature rising elution fractionation]
Measuring equipment: Model number "TREF equipment special type", manufactured by Senshu Kagaku Co., Ltd.
Column: Internal diameter 10mm x 300mm
Filler: Chromosolv P NAW (manufactured by GL Sciences, 30/60 mesh)
Sample solution concentration: 5 mg / mL
Sample solution injection volume: 2 mL
Solvent: Orthodichlorobenzene Flow rate: 1 mL / min
Sample injection temperature: 140 ° C
Temperature drop rate: 5 ° C / h
Cooling arrival temperature: 0 ° C
Maintenance time at cooling temperature: 30 minutes Temperature increase rate: 5 ° C / h
Detector: Infrared detector Measurement wave number: 3.42 μm

Effects of the Invention According to the present invention,
High fusing seal strength and less variation
Excellent optical properties such as haze, gloss and image clarity;
There is provided a polyolefin-based unstretched multilayer film that can exhibit an excellent antistatic effect even when the blending amount of the antistatic agent is small.
The polyolefin-based unstretched multilayer film of the present invention can be suitably used for fusing and sealing applications. The fusing seal bag manufactured from the film has high fusing seal strength, little variation in the sealing strength, excellent contents visibility, and is hardly charged.
Further, even when the polyolefin-based unstretched multilayer film of the present invention is subjected to, for example, corona discharge treatment, the strength of the gusset portion is not impaired. It is also possible.
Therefore, the fusing seal bag manufactured from the polyolefin-based unstretched multilayer film of the present invention is a package of shampoo, hair conditioner, body soap, detergent, etc. for refilling; a package of clothing; a package of documents and cards It can be used for applications such as body.

Claims

A polyolefin-based unstretched multilayer film in which an outermost layer A layer, an intermediate layer B layer and an outermost layer C layer are laminated in this order,
Each of the A layer and the C layer is formed from a polypropylene resin containing 50% by weight or more of a propylene-ethylene random copolymer polymerized using a metallocene catalyst,
B layer
Long chain branched LLDPE 15-75 wt%,
25 to 85% by weight of LLDPE (excluding the above-mentioned long chain branched LLDPE), and 30% by weight or less of the propylene propylene resin, provided that the total of the long chain branched LLDPE, LLDPE and polypropylene resin is 100% by weight As well as a polyolefin-based resin containing an antistatic agent,
The long chain branched LLDPE has the following conditions (1) to (3):
(1) The ratio Mw / Mn of the weight average molecular weight Mw in terms of polystyrene and the number average molecular weight Mn measured by gel permeation chromatography is 7.5 to 15.0.
(2) The amount of amorphous components measured by the temperature rising elution fractionation method is 1 to 4% by weight.
And (3) The number of branches having 8 or more carbon atoms measured by 13 C-NMR is 1.5 to 5.0 per 1,000 carbon atoms.
The multilayer film is characterized by satisfying all of the above and being used for fusing and sealing applications.
The content of the antistatic agent in the polyolefin resin for forming the B layer is 0.1 to 3 parts by weight with respect to 100 parts by weight of the total of the long-chain branched LLDPE, LLDPE and polypropylene resin contained in the resin. The multilayer film according to claim 1, wherein
The multilayer film according to claim 1, wherein the polypropylene resin used to form the A layer and the C layer does not contain an antistatic agent.
The total thickness of the multilayer film is 20 to 200 μm,
The multilayer film according to any one of claims 1 to 3, wherein the ratio of the thickness of the B layer to the total thickness of the multilayer film is 30 to 80%.
A fusing-seal bag manufactured from the multilayer film according to any one of claims 1 to 4.