JPH03125139A - Packaging material - Google Patents

Abstract

PURPOSE:To obtain the packaging material which can freely control the adhesive strength of blocking by using a tackiness imparting agent and a polyolefin resin of a low degree of polymn. to the innermost layer of multilayered coextruded inflation films. CONSTITUTION:The innermost layers 2 have the laminated films of the vertically symmetrical structure formed by having the multilayered coextruded inflation films 3 of a thermoplastic resin compsn. contg. 0.05 to 10wt.% polyolefin resin of the low degree of polymn., 0.05 to 10wt.% tackiness imparting agent and 0.01 to 0.8wt.% antioxidant and adhering the innermost layers 2 of the inflation films to each other by the blocking B. Pseudo adhesion is caused by the blocking in a soft state to some extent in the blocking adhesion of the innermost layers 2 without using any adhesive agent at all, by which the physical strength is improved and curling is prevented. The adhesive strength by the blocking is freely controlled by the amt. of the polyolefin resin of the low degree of polymn. and tackiness imparting agent used. The packaging material which can be surely blocked over the entire surface is thus obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is suitable for packaging products with excellent pinhole resistance, impact puncture strength, and tear strength, and sharp edges, especially for packaging various photographic materials and heavy products. Concerning suitable packaging materials.

[Prior Art] In general, packaging materials for cutting-edge technology products, such as photosensitive materials, not only completely block light, but also have gas barrier properties, moisture proof properties, physical strength (tensile strength, tear strength, impact puncture strength, gelbo test). Satisfies various properties such as strength, abrasion resistance, etc.), heat sealability (heat seal strength, cut sealing properties, hot tack properties, contaminant sealing properties, etc.), antistatic properties, lubricity, low dust generation, flatness, etc. required to do so. It is extremely difficult to provide all of these properties in a single film material, and conventionally packaging materials consisting of multiple layers have been used.

The present inventor conducted extensive research to improve packaging materials for photosensitive materials, and developed a material with improved physical strength by combining a 2N uniaxially stretched film (Japanese Patent Laid-Open No. 57-675
Publication No. 4) was disclosed.

The innermost layers of the multilayer coextruded blown film are bonded together by blocking, and the physical strength is thick (,
An inexpensive packaging material with low curl is also disclosed. (Unexamined Japanese Patent Publication No. 6
4-22544), (JP-A-1-110952), (JP-A-1-133736) [Problem to be Solved by the Invention] However, the packaging material described in JP-A-57-6754 Since these are laminated with adhesive layers, if the adhesive strength is high, each layer will be completely integrated and hardened, resulting in a problem of low physical strength and high cost due to large assembly losses.

In addition, Japanese Patent Application Laid-Open Nos. 1982-22544, 1999-110952, and 1997-1, which solved the above problems,
In the packaging material described in Publication No. 33736, blocking is not performed on the entire surface due to the cooling conditions during inflation film molding and changes in indoor temperature in midwinter, wrinkles and voids occur unevenly, and blocking adhesive strength is generally poor. 10g
It was small, less than /15mm wide.

An object of the present invention is to solve the above-mentioned problems and provide a packaging material that can freely adjust the adhesive force due to blocking and can reliably block the entire surface without modifying the ring die or inflation equipment.

[Means to solve the problem]

The present invention has achieved the above object by using a tackifier and a low polymerization degree polyolefin resin in the innermost layer of a multilayer coextruded blown film, that is, the blocking adhesive layer.

That is, in the packaging material of the present invention, the innermost layer contains 0.05 to 10% by weight of a low polymerization degree polyolefin resin and 0.0% by weight of a tackifier.
05-10 wt% and antioxidant 0.01-0.8 wt%
The invention is characterized by comprising a multilayer coextruded blown film made of a thermoplastic resin composition including the above, and a laminated film having a vertically symmetrical structure in which the innermost layers of the blown film are adhered to each other by blocking.

The packaging material of the present invention has a laminated film in which the innermost layers of a multilayer coextruded blown film are pseudo-adhered to each other by blocking.

This innermost layer blocking adhesive is not completely bonded and fixed as one with adhesive, but is pseudo-bonded in a somewhat flexible state by blocking without using adhesive to improve physical strength. It improves hair and prevents curling.

The adhesive strength due to the above blocking can be freely adjusted by the amount of low polymerization degree polyolefin resin and tackifier used.
For example, in the case of only a laminated film, the amount of the above two components is reduced to reduce the blocking adhesive strength and increase the physical strength and flexibility, and when the laminated film is laminated with other flexible sheets, the amount of these two components is increased. Increase the blocking adhesive strength (for example, 10g/15mm width or more),
Prevents wrinkles and voids during lamination due to partial voids due to insufficient adhesive strength and peeling.

The multilayer coextruded blown film may consist of only two layers, an innermost layer and an outer layer, or an intermediate layer may be provided between the innermost layer and the outer layer.

The laminated film is formed by blocking and laminating the innermost layers of a multilayer coextruded blown film, so it has a vertically symmetrical structure. In order to pseudo-adhere the innermost layer of a multilayer coextruded blown film by blocking, for example, when forming a multilayer coextruded blown film by the multilayer coextrusion inflation method, a new pressure bond is added to the take-off nip roll or the downstream stage of the take-off nip roll. This is done by pressing the innermost layers of thermoplastic resin composition together using a roll. The round die (ring die) used in the round die method multilayer coextrusion/blown film forming machine can be roughly divided into three types: the inside die lamination method, the outside die lamination method, and the laminar flow feeding method. Although a round die with a die-in-hole lamination method is preferable because it has a high interlayer adhesion force.

The low polymerization degree polyolefin resin used in the present invention preferably has a number average molecular weight of 300 to 7,000, particularly preferably 500 to 6,000, and most preferably 1,000 to 4,000.
It is. Typical polyolefin resins include polyethylene resin, ethylene copolymer resin, polypropylene resin, ethylene-propylene copolymer resin, and propylene-α-olefin copolymer resin.

If the number average molecular weight is less than 300, film formability will be deteriorated, and over time it will bleed out onto the film surface and be transferred to photographic materials, causing various problems such as development inhibition and developer contamination. The physical strength of the film also decreases. This is because if the number average molecular weight exceeds 7,000, the effect of improving film formability, blocking adhesion, etc. will be reduced.

The low polymerization degree polyolefin resin is contained in the inner layer in an amount of 0.05 to 10% by weight.

If it is less than 0.05% by weight, the effect of improving film formability, blocking adhesion, lubricity, etc. will be small and the kneading cost will only increase. If it exceeds 10% by weight, the melt flow rate (hereinafter referred to as MFR) of the thermoplastic resin composition will decrease. ) becomes too large, the bubbles tend to sway during blown film forming, bleed-out increases, and it becomes too slippery to roll up properly, and the physical strength of the film also decreases.

Examples of the tackifier used in the present invention are described below.

Natural minerals and their derivatives 1, containing 91 ■ Terpene phenol) I411N 2, Contains no polar groups (pentaerythritol ester, etc.) ■ Charcoal 7: 4 types of shoes ... goji/i
Todoroki (ri 11 synthesis #ifgI effect 1, heavy i 1 left 11 field effect 2, kumaron indene special effect 2, Rendaji 71 pillar clear effect tackifier is 0.05 to 10 times percent in the innermost layer) If it is less than 0.05% by weight, the effect of adding the tackifier will not be apparent, and if it exceeds 10% by weight, the film molded product will deteriorate and the strength of the film will be reduced.

As the thermoplastic resin which is the main component of the innermost layer of the present invention, for example, polyolefin resin, polyamide resin, polyester resin, PVA resin, polystyrene resin, etc. can be used.

Polyolefin resins, especially various types of polyethylene resins, are preferable because they are thin and strong, have appropriate hardness, are easy to handle, have moisture resistance, water resistance, chemical resistance, and are inexpensive. A polymeric ethylene copolymer resin (LLDPE resin, etc.) is preferred.

In addition, the packaging material of the present invention can also be used for fish eyes and spots (
It is preferable to add an antioxidant in order to prevent the occurrence of non-uniform hardening failures.

Representative examples of antioxidants are described below.

(a) Phenolic antioxidant 6-t-butyl-3-methylphenyl derivative, 2.6
-di-butyl-P-cresol, 2,6-butyl-4-ethylphenol, 2,2゛-methylenebis-(
4-ethyl-6-t-butylphenol), 4・4°-
butylidene bis(6-t-butyl-m-cresol),
4,4-dihydroxydiphenylcyclohexane, alkylated bisphenol, styrenated phenol, 2,6
-di-t-butyl-4-methylphenol, n-octadecyl-3-(3° ・5°-di-t-butyl-4”-
Hydroxyphenyl)propinate, 2,2゛-methylenebis(4-methyl-6-t-butylphenol), 4
・4'-thiobis(3-methyl-6-t,-butylphenyl), 4,4'butylidenebis(3-methyl-6-t,-butylphenyl)
t-butylphenol), stearyl-β(3,5-di-4-butyl-4-hydroxyphenyl)propionate, 1,1,3-tris(2-methyl-4hydroxy-
5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4
Hydroxybenzyl) Benzene, Tetrakis [Methylene-3(3”・5”-di-1-butyl-4”-hydroxyphenyl)propionate Comethane(b)ketone Amine condensation antioxidant 6-Nitoxy 2.2.4- Polymer of trimethyl-1,2-dihydroquinoline, 2,2,4-trimethylto-2-dihydroquinoline, trimethyldihydroquinoline derivative (iii) Allylamine antioxidant phenyl-α-naphthylamine, N-phenyl-β- Naphthylamine, N-phenyl-N"-isopropyl-P
-Phenylene diamine, N-N'-Siferny P-phenyl diamine, N-N”-di-β-naphthyl-P-
Phenylene diamine, N-(3°-hydroxybutylidene)-1-naphthylamine (di)imidazole antioxidant 2-mercaptobenzimidazole, zinc salt of 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole (v)phos Phyto-based antioxidants Alkylated allyl phosphite, diphenylisodecyl phosphite, tris(nonylphenyl) phosphite Sodium phosphite, trinonylphenyl phosphite, triphenyl phosphite (he)thiourea-based antioxidants thiourea Derivatives, 1,3-bis(dimethylaminopropyl)-2-thiourea(t)Other air oxidation di-Useful antioxidants Dilauryl thiodipropionate Typical commercially available antioxidants are shown below.

(1) Phenolic antioxidant; (1)-1, Monophenolic antioxidant Antige B
IIT, DAH, DBII, SP, LP-
1 (Kawaguchi Chemical Industry), old osol A, same N (Osaka Kasei), 17 riser-MS-7, same sp, same 200, same M1
7 (Iriuchi Shinko Kagaku Kogyo), BIT Swanox, Stearer-Alha, Doki (Kanou Chemical), Sumilizer A1
BIIT, L (Jumin Chemical Industry), BHA-Wako
(Wako Pure Chemical), Yoshihax BIT,) Minox S
S (Yoshitomi Pharmaceutical), lrganox 1076 (Musashino Geigy), Amoco 533 Antioxida
nt (Amoco chem), Antioxida
nt KB (Bayer), Tenox BIT (
Easttaan chew) '[Eihyl'' A
nti.

xidant 698, 7011 703, 733
, 762 (1! iyl corp), Topan
ol 354, A1 01 0C (1, C, I),
Ionol, Ionol 99, Ionol 100 (Sh
ell cheII+), -UOP7, cheII19 (UO
P Chew), Naugard BHT, Na
ugawhite 434 (Uniroyal c
hen+), Age Rite 5uper (Va
(1)-2, bisphenol antioxidant ANTAGE R
e, W-300, W-400, W-500, Crystal 2LX (Kawaguchi Chemical Industry), Tsukurizer MS
-6, 300 (Iriuchi Shinko Kagaku Kogyo), Sundant 22
46 (Sandan Kagaku Kogyo), Steerer-BB, same BPS,
Same BPS-R, same 1! PP, MBP (Kekiko Chemical)
, Seenox BC5 (Shipro Kasei), Sumilizer B
BM, MDP.

Same-X, Same WX-R (Jumin Chemical Industry), Sufnox 4
25 (Maruzen Petrochemical), Yonnox 2246G, 2246R1 BB, SR, 425 (Yoshitomi Pharmaceutical)
, Plastanox 425, Plastanox 2246 (6m C
yanaiaid), Antioxidant BK
F (Bayer), “Eihyl” Antioxida
nt 702, 712, 720, 736 (1
! 1hyl Corp), Santwhite cr
y stalg < same 1 same MK, same posvder (
Monsant), Ionox 220, Ionox 901 (S
Hell Chew), Age Rite 5upe
rlite (Vanderbilt) (1)-3, polymeric phenolic antioxidant SECA/7
Kusu 201 (Osaka Sakka Kogyo), antioxidan
tHoechst TMOZ (Hoechst Japan)
, IrganoxlOlo, 565 (Musashino Geigy), Plastanox 80, 1729 (Am
, Cyanamide), Irganox191,
259, 858, 1093, 1222 (Cib
a-Geigy), “Eihyl” Antioxida
nt 796 (Eihyl Corp), Good
Rite 3114, Rite 3125 (Good rich
), TopanoICA (1,C,I), Ionox
330 (ShellChem) (2) Sulfur-based antioxidant Lasmit, SS (Daiichi Kogyo Seiyaku), Kyonox, DS (Shibro Kasei), Sumilizer TPS (Suminami Kagaku Kogyo), DLTP r Yoshitomi J, DMTP
r Yoshitomi J, DSTP r Yoshitomi' (Yoshitomi Pharmaceutical), Plastanox LTDP, Plastanox STDP (
Am, Cyanamide) (3) Phosphorous antioxidant JP360, 351, 355, 212, 30
8, 310, 504, 50B, JPPloo,
613M, 2000, JA805, HBP,
JPH3800, JPM311, JPM313 (Johoku Chemical Industry), Antige TNP (Kawaguchi Chemical Industry), Tsukurizer TNP (Iriuchi Shinko Chemical Industry), Chle
x C1° Same D2 Same Men, Same MD, Same 01 Same P1 Same T1 Same TO (Sakai Chemical Industry), Sumilizer TNP, Same TPP
, TPP-R, Mark 329, POP-8260
(Jumin Chemical Industry).

The antioxidant is preferably contained in the innermost layer in an amount of 0.01 to 0.8% by weight. If it is less than 0.01% by weight, the antioxidant effect will be low and resin burning will occur during blown film molding, and if it exceeds 0.8% by weight, it will bleed out to the outer surface of the film over time after film molding, causing various problems. cause In particular, when used as a photographic material, it is not preferable because it deteriorates the quality of the photographic material.

In the packaging material of the present invention, a light-blocking substance can be added to each layer of the multilayer coextruded blown film to ensure light-blocking properties.

As the light-blocking substance, conventionally known light-blocking substances are used.
Among these light-shielding substances, carbon black is preferred because it can reduce the amount of bleed-out, has the effect of preventing oxidation of the resin, is inexpensive, and has a large light-shielding ability.

Examples of particularly preferred classifications of carbon black materials include gas black, furnace black, channel black, anthracene black, acetylene black, ketchiene carbon black, thermal black, lamp black, oil smoke, powder smoke, animal black, and vegetable black. be. In the present invention, furnace carbon black is preferable for the purpose of improving light-shielding properties, cost, and physical properties, and acetylene carbon black and Ketchiene carbon black, which is a modified by-product carbon black, are preferable as light-shielding substances that are expensive but have antistatic effects. .

It is also preferable to mix the former and the latter according to the required characteristics, if necessary. When using Kettin carbon black as a packaging material for photographic light-sensitive materials, it is necessary to consider the amount of addition, venting, etc. of Kettin carbon black, which has a high content of heavy metals.

Especially pH 6.0-9.0, average particle size 10-120m
μ, volatile component 2.0% or less, oil absorption 1i50Inl/10
Furnace carbon black in an amount of 0 g or more is preferable because it does not give a bad shadow to photographic light-sensitive materials, has a large light-shielding ability, and is inexpensive.

In addition, various additives may be used in the present invention if necessary.

Next, typical examples of additives are described below, but the present invention is not limited thereto, and additives can be selected from all known additives.

(Additive type) (Representative example) (1) Plasticizer
; Phthalate ester, glycol ester, fatty acid ester, phosphate ester, etc. (2) Stabilizer; Lead-based, cadmium-based, zinc-based, alkaline earth metal-based, organotin-based, etc. (3) Antistatic agent; Cationic type Surfactants, anionic surfactants, nonionic surfactants, amphoteric surfactants, various carbon blacks, metal powders, graphite, etc. (4) Lubricants; silicone-based lubricants, fatty acid amide-based lubricants, alkylamine-based Lubricants, etc. (5) Flame retardants; phosphate esters, halogenated phosphate esters, halides, 88! (6) Fillers: alumina, kaolin, clay calcium carbonate, mica, talc, titanium oxide, silica, etc. (7) Reinforcers: glass roving, metal fiber, glass fiber, glass milled fiber, carbon fiber etc. (8) Blowing agents) Inorganic blowing agents (ammonia carbonate, sodium bicarbonate), organic blowing agents such as troso type, azo type), etc. (9) Vulcanizing agents; Vulcanization accelerators, accelerators, etc. (10) Anti-deterioration agents ; Ultraviolet absorbers, antioxidants, metal deactivators, peroxide decomposers, etc. (11) Coupling agents; Silane-based, titanate-based, chromium-based, aluminum-based, etc.; (12) Various thermoplastic resins; Rubber, etc. (13) Nucleating agent; organic nucleating agent (dibenzylidene sorbitol compound, etc.)
, inorganic nucleating agents (calcium carbonate, etc.), etc. The packaging material of the present invention can be used for photographic materials, foodstuffs, pharmaceuticals,
Suitable for chemical substances, etc.

It is particularly suitable for reinforced bags that require physical strength, antistatic properties, heat sealing strength, moisture proofing properties, pinhole resistance, drop strength, and suitability for bag making. When used as a packaging material containing a light-shielding substance or an antistatic agent, it is most suitable as a light-shielding bag for photographic materials.

When the packaging material of the present invention is applied to, for example, the above-mentioned photographic materials, - Vertical flat bags, double flat bags, self-standing bags, - heavy gusset bags, double gusset bags, laminated films, inner lining of moisture-proof boxes, bright room loading. It can be used for all known forms such as the inner lining of light-shielding magazines, inner bags, and leader paper.

The bag making method is based on conventionally known plastic film sealing methods such as heat sealing, fusing sealing, impulse sealing, ultrasonic sealing, and high frequency sealing, depending on the properties of the laminated film used. Note that it is also possible to make bags using an appropriate adhesive, adhesive, or the like.

[For production]

In the packaging material of the present invention, the low polymerization degree polyolefin resin and the tackifier in the innermost layer have a large influence on the blocking adhesive strength, and the blocking adhesive strength is adjusted by the amount of these additives.

〔Example〕

Examples of packaging materials according to the present invention are shown in FIGS. 1 to 7 below.
This will be explained based on the diagram.

1 to 7 are partial cross-sectional views showing the layer structure of the packaging material of the present invention.

The packaging material shown in FIG.
The outer thermoplastic resin layer 1 and the inner thermoplastic resin layer 2 are a two-layer coextrusion blown film 3 formed by a Marugui method two-layer coextrusion blown film molding machine.

The thermoplastic resin inner layers 2 and 2 are bonded together by blocking (blocking adhesive portion B), thereby forming a blocking laminated film 4.

The packaging material shown in FIG. 2 is the same as the packaging material shown in FIG. 1, except for the use of a thermoplastic resin inner layer 2a containing a light blocking substance.

The packaging material shown in FIG. 3 is the same as the packaging material in FIG. 1 except for the use of a thermoplastic resin outer layer 1a containing a light blocking substance.

The packaging material shown in FIG. 4 is the same as the packaging material shown in FIG. 1, except that an outer thermoplastic resin layer 1a containing a light-blocking substance and an inner thermoplastic resin layer 2a containing a light-blocking substance are used.

The packaging material shown in FIG. 5 is an aluminum vacuum-deposited biaxially oriented polyester film obtained by processing an aluminum vacuum-deposited layer 7 on a biaxially oriented polyester film 6 via an adhesive layer 5 on the blocking laminated film 4a shown in FIG. 8
It has a laminated structure.

The packaging material shown in FIG. 6 includes a thermoplastic resin outer layer 1°1,
It consists of six layers: an intermediate layer 6.6, and thermoplastic resin inner layers 2a and 2a containing a light-blocking substance, and these thermoplastic resin outer layer 1, middle layer 6, and thermoplastic resin inner layer 2a containing a light-blocking substance are This is a three-layer coextrusion blown film 9a molded using a Marugui method three-layer coextrusion blown film molding machine. Then, blocking adhesive is applied between the thermoplastic resin inner layers 2a and 2a containing a light-blocking substance,
A blocking laminated film 4a is configured.

The packaging material shown in FIG. 7 has a metal layer 10 laminated on the blocking laminated film 4a shown in FIG. It has a structure in which flexible sheets 11 are laminated with each other interposed therebetween.

Invention product I The layer structure corresponds to that shown in FIG.

The thermoplastic resin outer layer 1a has an MFR of 1.1 g/10 minutes,
15% by weight of high-density homopolyethylene resin with a density of 0.954g/cfflO, MFR of 2.4g/10 min, 6% by weight of high-pressure low-density homopolyethylene resin with a density of 0.923g/-, ° average particle size of 21mp 4% by weight of furnace carbon black, nonionic surfactant (trade name
Electro Stripper TS-3, manufactured by Kao ■) 0.1% by weight, MFR 2 containing 0.05% by weight of erucic acid amide
．． 1g/10 minutes, density 0.920g/cfl! This is a light-shielding ethylene copolymer-based resin film with a thickness of 12 μm, whose main resin is an ethylene/4-methylpentene-1 copolymer-based resin.

The thermoplastic resin inner layer 2a is made of a low molecular weight polyethylene resin with an average molecular weight of about 2000 manufactured by Mitsui Petrochemical Co., Ltd. (trade name: Mikata Hiwax 22) as a low polymerization degree polyolefin resin.
0MP) 2% by weight, used as a tackifier by Forestry Chemical ■
Alicyclic saturated hydrocarbon resin (product name Alcon P-9
0) 3% by weight, 3% by weight of furnace carbon black with an average particle size of 21 m μ, 0.05% by weight of monophenolic antioxidant, 0.05% by weight of polymeric phenolic antioxidant.
MFR containing 0.05% by weight is 2.1g/10min, density is 0.05% by weight.
92h/cd ethylene/4-methylpentene-1 copolymer resin manufactured by Mitsui Petrochemical ■ (trade name: Urtozex #)
It is a light-shielding ethylene copolymer-based resin film with a thickness of 13 μm and whose main resin is 2021L).

Blocking was performed using a nip roll of a commonly used two-layer coextrusion blown film forming machine to obtain a four-layer blocking laminate film with a total thickness of 50 μm.

This invention■ The layer structure corresponds to that shown in FIG.

The thermoplastic resin outer layer 1a has an MFR of 0.4 g/10 minutes,
Density is 0.965g/cn! This is a 10 μm thick light-shielding polyethylene resin film made of 97% by weight of high-density homopolyethylene resin and 3% by weight of acetylene carbon black (manufactured by Denki Kagaku).

The thermoplastic resin inner layer 2a is made of Mitsui Hiwax 220MP, which is the same as the product T of the present invention, as a low polymerization degree polyolefin resin.
3 weight%, 4% by weight of styrene resin (trade name FTR6080) manufactured by Mitsui Petrochemical ■ as a tackifier, 7% by weight of acetylene carbon black (mentioned above), 0.05% by weight of monophenolic antioxidant, MFR including 0.05% by weight of polymeric antioxidant is 1.0g/10min,
Ethylene-butene 1 copolymer resin manufactured by Union Carbide Co., Ltd. (trade name NUX) with a density of 0.890 g/cflf
-FLX-DEFD-1210, a 15 μm thick light-shielding ultra-low-density polyethylene resin film whose main resin is ultra-low-density polyethylene resin.

This two-layer coextruded blown film consisting of two layers was subjected to blocking adhesion in the same manner as Invention Product I to obtain a blocking laminate film having a four-layer structure and a total thickness of 50 μm. Inventive product ① The layer structure corresponds to that shown in FIG.

The thermoplastic resin outer layer 1a has a thickness of 12
It is a light-shielding ethylene copolymer resin film of μm.

N2a in the thermoplastic resin is a low molecular weight polyethylene resin with an average molecular weight of approximately 4000 manufactured by Mitsui Petrochemicals (trade name: Mitsui Hiwax 4) as a low polymerization degree polyolefin resin.
20P) 3% by weight, Mikata Petrochemical as a tackifier■
aliphatic hydrocarbon resin (product name Hilets T-11)
15) 3% by weight, 3% by weight of furnace carbon black with an average particle diameter of 21 mμ, 0.05% by weight of monophenolic antioxidant, 0.05% by weight of polymeric phenolic antioxidant, 0.0% by weight of antistatic agent. MFR containing 1% by weight
A light-shielding high-pressure homopolyethylene resin with a thickness of 13 μm, whose main resin is a high-pressure process low-density homopolyethylene resin (trade name: Novatek LP-1210) made by Mitsubishi Kasei ■, with a density of 0.8 g/10 minutes and a density of 0.924 g/rd. It is a polyethylene resin film.

This two-layer coextruded blown film consisting of two layers was subjected to blocking adhesion in the same manner as the product ① of the present invention to obtain a blocking laminate film having a four-layer structure and a total thickness of 50 μm.

Invention product ■ The layer structure corresponds to that shown in FIG.

The thermoplastic resin outer layer 1a containing a light-shielding substance is a light-shielding ethylene copolymer resin film having a thickness of 12 μm, which is the same as that of the product ① of the present invention.

The thermoplastic resin inner layer 2a is made of high-pressure low-density homopolyethylene resin (trade name: NOVATECOO LP-1) as the main resin.
This is a light-shielding EVA resin film having a thickness of 13 μm and having the same composition as the product of the present invention (2), except that an EVA resin (trade name: Evaflex #480) manufactured by Dupont Polychemical Cal (21E) is used instead of (21E).

This two-layer coextruded blown film consisting of two layers was subjected to blocking adhesion in the same manner as the product ① of the present invention to obtain a blocking laminate film having a four-layer structure and a total thickness of 50 μm.

Comparison product■ The layer structure is similar to that in FIG.

The product (2) of the present invention is completely the same as the product (2) of the present invention except that the low polymerization degree polyolefin resin and the tackifier are removed from the light-shielding ethylene copolymer resin film that is the thermoplastic resin inner layer 2a.

Comparison product■ The layer structure is similar to that in FIG.

In the product (■) of the present invention, the low polymerization degree polyolefin resin and the tackifier are removed from the light-shielding high-pressure homopolyethylene resin film that is the thermoplastic resin inner layer 2a.
is exactly the same.

The test results are shown in Table 1.

The evaluation is based on the following.

◎...Excellent ○...Excellent...Acceptable (within practical limits) Mu...Problems (improvement required) ×...Not practical*1 Blocking adhesion samples Using the two-layer coextrusion blown film forming machine described on page 29, under the film forming conditions,
Evaluation based on the adhesion state of the innermost layer when wound up into a roll as shown in the figure *2 When each sample of wrinkles and streaks was created using the two-layer extrusion blown film molding machine described on page 29 under the film molding conditions. Evaluate the degree of occurrence of wrinkles and streaks by visual inspection *3 Massive non-uniform failure When each sample is produced using a two-layer coextrusion blown film forming machine under the film forming conditions described on page 29, the difficulty in generating wrinkles. Evaluate the degree of film appearance by visual inspection *4 Film formability When each sample was created using the two-layer coextrusion blown film forming machine described on page 29 under the film forming conditions, the stability of the bubbles, the appearance of the roll, etc. More comprehensive evaluation [Effects of the Invention] By configuring the present invention as described above, the blocking adhesive force can be freely controlled, so even resins with a large Young's modulus can be blocked and bonded. It is possible to control the blocking adhesive strength to an appropriate level so that wrinkles, voids, etc. do not occur, and the physical strength is sufficient.

[Brief explanation of the drawing]

1 to 7 are partial cross-sectional views showing the layer structure of an example of the packaging material of the present invention. FIG. 8 is a diagram showing a situation in which a sample is wound up from a coextrusion molding machine. 1, la...Thermoplastic resin outer layer 2.28...Thermoplastic resin inner layer 3.3a...Two-layer coextruded film 4.4a...
... Blocking laminated film 5.5a ... Indicates that the three-layer coextruded film a contains a light-shielding substance. B shows the blocking adhesive part.

Claims (1)

[Claims] The innermost layer is a low polymerization degree polyolefin resin 0.05-10% by weight, a tackifier 0.05-10% by weight, and an antioxidant 0.
．． A packaging material comprising a multilayer coextruded blown film made of a thermoplastic resin composition containing 0.01 to 0.8% by weight, and a laminated film in which the innermost layers of the blown film are adhered to each other by blocking.