JP3259588B2 - Heat and moisture proof film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat and moisture resistant film having both heat resistance and moisture resistance and suitable for packaging.

[0002]

2. Description of the Related Art It has been known that the addition of petroleum resin and terpene resin to polypropylene improves Young's modulus and moisture resistance (Japanese Patent Publication No. 1-25033, Japanese Patent Publication No. 3-31347). It is also known that metal vapor deposition and polyvinylidene chloride-based resin are laminated on a film obtained by adding a petroleum resin and a terpene resin to polypropylene to further improve the moisture-proof property (Japanese Patent Publication No. Hei 2 (1994)).
-27940, Japanese Patent Publication No. 5-1138, etc.).

[0003]

However, when a petroleum resin and a terpene resin are added to polypropylene, the Young's modulus and moisture resistance are improved. However, since the petroleum resin and the terpene resin have a low softening point, the film to which these are added cannot be used. It is inferior in dimensional stability, and when the film is wound into a roll, tightening occurs and the flatness deteriorates. In addition, there is a problem that the process stability during processing is inferior due to a large heat shrinkage.

Further, when a metal is vapor-deposited on the film to give it a further moisture-proof property, the film is shrunk by heat at the time of vapor deposition, cracks are formed on the metal-deposited surface, and the moisture-proof property is not improved. was there.

Further, when a polyvinylidene chloride-based resin is coated to further impart moisture-proof properties, the film shrinks due to the heat of drying after coating, causing cracks in the coating resin layer, and polypropylene. There was a problem that the interfacial adhesive strength with the film was lowered and the moisture resistance was not improved.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional disadvantages, and has excellent heat resistance, moisture resistance and thickness unevenness during film formation, and excellent dimensional stability during printing and vapor deposition. The purpose is to provide a film.

[0007]

In order to achieve the above object, the heat and moisture resistant film of the present invention has an isothermal crystallization time at 125 ° C. of 3.5 minutes or less and an isotactic index of 98.5% or more. , Melt flow index is 2
4 g / 10 minutes of crystalline polypropylene 70 to 95% by weight
A film in which at least one kind of a petroleum resin substantially free of a polar group and a terpene resin substantially free of a polar group is mixed at 5 to 30% by weight, and heated at 120 ° C. for 15 minutes. The thermal contraction rate in the direction is 5% or less, and the water vapor transmission rate is 1.0 (g / m ² · 24 hr / 0.1 mm) or less.

Further, the heat and moisture resistant film according to the present invention comprises:
A crystalline polypropylene having an isotactic index of 98% or less is laminated on at least one surface of the heat-resistant and moisture-proof film (hereinafter sometimes referred to as a layer A) (hereinafter sometimes referred to as a layer B). Characterized by the following.

The crystalline polypropylene of the layer A of the present invention comprises:
The isothermal crystallization time at 125 ° C. (hereinafter sometimes abbreviated as t- ／) is 3.5 minutes or less, and the isotactic index (hereinafter sometimes abbreviated as II).
Should be 98.5% or more. t-1 / 2
If it exceeds 3.5 minutes and II is less than 98.5%, the crystallinity of the film does not increase, and the heat shrinkage in the longitudinal direction at 120 ° C. for 15 minutes becomes 5% or more, which is not preferable. It is not preferable because the organic solvent resistance is also deteriorated. When the melt flow index (MFI) is in the range of 2 to 4 g / 10 minutes, the dispersibility of the petroleum resin and / or the terpene resin is improved, and the film forming property and the moisture resistance are also improved. Further, a small amount of a second component other than propylene, for example, ethylene, butene, hexene or the like may be randomly copolymerized. In addition, known additives such as a crystal nucleating agent, an antioxidant, a heat stabilizer, a slipping agent, an antistatic agent, an antiblocking agent, a filler, a viscosity modifier, and a coloring inhibitor may be contained in appropriate amounts.

In the present invention, the petroleum resin which does not substantially contain a polar group and is mixed with the crystalline polypropylene has a polar group comprising a hydroxyl group, a carboxyl group, a halogen group, a sulfone group and a modified product thereof. No petroleum resin, that is, a resin that is mainly made of a cyclopentadiene-based hydrocarbon or a higher olefin-based hydrocarbon directly using a petroleum unsaturated hydrocarbon as a raw material.

The glass transition temperature (hereinafter abbreviated as Tg) of a petroleum resin substantially free of such a polar group is 60
It is preferable that the temperature is not lower than ° C. When Tg is less than 60 ° C,
The effect of improving the moisture resistance is small.

A hydrogenated petroleum resin obtained by adding hydrogen to such a petroleum resin and having a hydrogenation ratio of 90% or more, preferably 99% or more, is particularly desirable for the heat and moisture resistant film of the present invention. Typical hydrogenated petroleum resins include, for example, Tg
High Tg completely hydrogenated alicyclic petroleum resins such as polydicyclopentadiene having a hydrogenation ratio of 99% or more at 70 ° C. or more can be given.

The term "terpene resin containing substantially no polar group" refers to a terpene resin having no polar group, such as a hydroxyl group, an aldehyde group, a ketone group, a carboxyl group, a halogen group, a sulfone group or a modified form thereof. , Ie (C
₅ H ₈₎ is a hydrocarbon and now modified compound derived composition of n. n is a natural number of about 2 to 20.

The terpene resin is sometimes referred to as a terpenoid, and typical compounds include pinene, dipentene, karen, myrcene, osimene, limonene, terpinolene, terpinene, sabinene, tricyclene, bisabolene, zingiperene, santalen, camphorene, There are millen and totalene, and in the case of the film of the present invention, hydrogen is added and the hydrogenation rate is 90% or more, preferably 9%.
9% or more, particularly β-pinene, hydrogen β
-Pinene, hydrogenated β-dipentene and the like are preferred.

As described above, the use of at least one of a petroleum resin substantially free of a polar group and a terpene resin substantially free of a polar group is important in the present invention. Is preferably 5 or less, more preferably 1 or less.

The amount of at least one of the petroleum resin substantially free of the polar group and the terpene resin substantially free of the polar group contained in the film of the present invention is 70 to 95% by weight of the crystalline polypropylene. % To 5% by weight. In particular, it is preferably from 10 to 20% by weight. If the amount of the resin is less than 5% by weight, the moisture-proof property is not improved, and if it exceeds 30% by weight, not only the heat resistance is deteriorated, but also the resin bleeds out to the surface layer, and the adhesive strength of the laminated resin and metal It is not preferable because the adhesion of the deposition is reduced.

The film of the present invention has a temperature of 120.degree.
The heat shrinkage in the longitudinal direction after heating for 5 minutes needs to be 5% or less, preferably 3% or less. When the heat shrinkage in the longitudinal direction exceeds 5%, when the film is wound into a roll, the film is tightened and the flatness is deteriorated. Also, since the heat shrinkage is large, the pitch deviation of the print after printing, Wrinkles occur during application of the adhesive or lamination, resulting in poor process stability.

Further, when a film is deposited on the film to give a further moisture-proof property, the film shrinks due to the heat during the deposition, and the film shrinks due to the heat when extruded and laminated on the metal deposition surface. As a result, cracks are formed on the metal-deposited surface, and the moisture resistance is not improved.

Furthermore, when a polyvinylidene chloride-based resin is coated to further impart moisture-proof properties, the film shrinks due to the heat of drying after the coating, causing cracks in the coating resin layer and / or polypropylene. The interfacial adhesion to the film is reduced, and the moisture resistance is not improved.

The film of the present invention must have a water vapor transmission rate of 1.0 (g / m ² · 24 hr / 0.1 mm) or less. Water vapor transmission rate of 1.0 (g / m ² · 24h
(r / 0.1 mm), when the film is used for moisture-proof packaging that requires moisture-proof properties such as dry matter and potato chips, the content is moist and the content-protection is poor.
Further, in applications requiring moisture resistance, it is necessary to increase the film thickness of metal vapor deposition and the coating thickness of polyvinylidene chloride resin, which inevitably leads to an increase in price and coloring.

The film of the present invention is unstretched, uniaxially stretched,
Although any of biaxially stretched films may be used, biaxially stretched films are preferred from the viewpoints of mechanical properties, optical properties, thermal properties, moisture resistance and the like.

Next, the heat- and moisture-proof film of the present invention (layer A)
Is a crystalline polypropylene having an isotactic index (II) of 98% or less. I of crystalline polypropylene in layer B
When I exceeds 98%, the crystallization is increased, the roughness of the film surface is increased, the external haze is increased, and the transparency is deteriorated. In addition, adhesion of metal vapor deposition and polyvinylidene chloride-based resin is also deteriorated.

Further, a small amount of a second component other than propylene, for example, ethylene, butene, hexene or the like may be randomly copolymerized with the crystalline polypropylene of the layer B. Further, known additives such as a crystal nucleating agent, an antioxidant, a heat stabilizer, a sliding agent, an antistatic agent, an antiblocking agent, a filler, a viscosity modifier, and a coloring inhibitor may be contained.

The thickness of the laminated B layer is 1
To 50 μm, more preferably 2 to 30 μm
It is. If the thickness is less than 1 μm, not only the moisture resistance and the hydrogenated petroleum resin or hydrogenated terpene resin bleed out to the surface layer, but also the adhesion of metal vapor deposition and polyvinylidene chloride resin decreases, It is not preferable because oil resistance for preventing oil seepage at the time of packaging of oils is reduced.
On the other hand, when the thickness exceeds 50 μm, the heat shrinkage increases, heat resistance deteriorates, and moisture resistance deteriorates.

The layer B to be laminated may be any of unstretched, uniaxially stretched and biaxially stretched. However, from the viewpoint of mechanical properties, optical properties, thermal properties and moisture resistance, the heat and moisture resistant film ( The biaxially stretched film is preferably co-extruded with the resin of layer A).

When the film of the present invention is printed, coated, vapor-deposited, or the like, it is preferable to perform a corona discharge treatment or a plasma treatment on the film surface in order to increase the adhesive strength. A known method can be used for the corona discharge treatment, but air, carbon dioxide gas, nitrogen gas, and a mixed gas thereof are preferable as the atmosphere gas at the time of the treatment. The plasma treatment includes a method in which various gases are kept in a plasma state to chemically modify the film surface, for example, a method described in JP-A-59-98140.

Further, when the metal vapor deposition and the polyvinylidene chloride-based resin are coated on the heat- and moisture-proof film of the present invention to further improve the moisture-proof property, the film thickness and the coating thickness of the vapor-deposited film and the coating thickness are reduced as compared with ordinary propylene film. It can be made thin and can be a low-cost ultra-moisture-proof film.

The metals to be deposited are aluminum, zinc,
Metals such as silicon, gold, silver and the like, and one or more metal compounds thereof and metal oxides thereof. Among them, aluminum is preferable because of its low cost and good economy.

The polyvinylidene chloride-based resin is not particularly limited, and includes a homopolymer of vinylidene chloride and a copolymer of vinylidene chloride.

Next, an example of the method for producing the heat and moisture resistant film of the present invention will be described. The crystalline polypropylene at 125 ° C. has a t-1 / 2 of 3.5 minutes or less, II of 98.5% or more, and a melt flow index of 2 to 4 g / 10 minutes. An A-layer resin composed of a mixture of a specific range of a petroleum resin and a terpene resin substantially free of a polar group was supplied to an extruder and melt-mixed at a resin temperature of 200 ° C or higher, preferably 220 ° C to 280 ° C. Thereafter, the sheet is extruded from a T-shaped die into a sheet, and the sheet is subjected to a draft ratio (lip gap of die / thickness of film) of 1.2 or more, preferably 1.5 to 3.0.
It is wound around a drum at a temperature of 0 to 100 ° C., preferably 50 to 80 ° C., cooled and solidified.
The sheet is preheated by passing it through an oven kept at 150 ° C., and then the sheet is kept at a temperature of 80 ° C. to 150 ° C. and passed between rolls provided with a peripheral speed difference, and stretched 2 to 6 times in the longitudinal direction. Cool to room temperature. Subsequently, the stretched film is guided to a tenter, and a temperature of 170 ° C. or less, preferably 140 ° C.
The film is stretched 5 to 10 times in the width direction at a temperature of １６165 ° C., and then relaxed by 2 to 20% in the width direction,
It is heat-set at a temperature of 0 ° C. and wound. In addition, for lamination of the B layer resin of crystalline polypropylene having II of 98% or less, the resin of the B layer is supplied to another extruder and melted at a temperature of 220 to 280 ° C., and then is formed by a multilayer molding die. After merging in a die so as to have a structure of B layer / A layer or B layer / A layer / B layer, it is formed into a laminated sheet. Further, as another laminating method, after the A-layer resin and the B-layer resin are merged in a short pipe upstream of the die, they are formed into a sheet shape with a T-type die, or in the longitudinal direction in the film forming step. A method is used in which the resin of layer B is extrusion-laminated on the stretched stretched film, the laminated film is guided to a tenter, and stretched in the width direction.
Specifically, the resin of layer B is supplied to an extruder, and
After being melted at a temperature of 80 ° C., it is melt-extruded into a sheet by a crow mouth-type die, and the molten sheet is stretched in the longitudinal direction between a cooling roll and a rubber roll at a temperature of 5 to 50 ° C. Bond and crimp.

Next, a film obtained by vapor-depositing a metal on the heat-resistant and moisture-proof film of the present invention can be obtained, for example, by laminating a metal to a desired film thickness using a vacuum vapor deposition machine.

The coating of the polyvinylidene chloride resin is carried out by a usual method such as a roll coater, a gravure roll, a rod coater, a spray coater and the like. Drying depends on the line speed. And dried.

The film of the present invention may be coated with additives such as an antistatic agent, a weathering agent, an antifogging agent, a slipping agent, etc., depending on the purpose. Further, a known treatment such as a corona discharge treatment may be performed in an air atmosphere, an inert gas atmosphere, or the like for the purpose of surface modification.

The film of the present invention can be used after embossing, printing, extrusion lamination, laminating with another resin film, paper, cloth or the like according to the purpose.

[Method of measuring characteristics and method of evaluating effects]
The method for measuring the characteristic values and the method for evaluating the effects of the present invention are as follows. (1) Intrinsic viscosity [η] 0.1 g of a sample was completely dissolved in 100 ml of tetralin at 135 ° C., and this solution was measured in a thermostat at 135 ° C. with a viscometer. Ask. The unit is dl / g. [Η] = (S / 0.1) × (1 + 0.22 × S)

(2) Isotactic index (I
I) The measurement may be performed individually in the raw material state. In the case of the composite film, the sample is first extracted with n-heptane at a temperature of 60 ° C. or less for 2 hours to remove additives to propylene.
Thereafter, vacuum drying is performed at 130 ° C. for 2 hours. From now on weight W
Take (mg) sample, place in Soxhlet extractor and extract with boiling n-heptane for 12 hours. Next, the sample is taken out, sufficiently washed with acetone, vacuum-dried at 130 ° C. for 6 hours, and then cooled to room temperature, the weight W ′ (mg) is measured, and it is determined by the following equation. II (%) = (W ′ / W) × 100 For the composite layer, the surface layer may be scraped off and measured by the same method as described above.

(3) Glass transition temperature (Tg) and isothermal crystallization time (t-1 / 2) In the state of the raw material, the measurement may be performed individually. In the case of the composite film, the sample is first heated to a temperature of 60 ° C. or less. For 2 hours to separate propylene from petroleum resin and terpene resin. Then, propylene is vacuum dried at 130 ° C. and petroleum resin and terpene resin are dried at 60 ° C. for 2 hours. Then, for each sample, a differential scanning calorimeter (DSC-
2 type, manufactured by PerkinElmer Co., Ltd.)
When the temperature was raised from room temperature at a rate of 20 ° C./min, the change in specific heat accompanying the second-order transition type was defined as the glass transition temperature (Tg), and then to the melting holding temperature of 280 ° C. After raising the temperature and holding for 5 minutes, the mixture was cooled at a cooling rate of 20 ° C./min. When the temperature was held at 125 ° C., the start time and end time of the peak of the latent heat accompanying crystallization were recorded. Half the time was taken as the isothermal crystallization time (t-1 / 2). In addition, about a composite layer, what is necessary is just to scrape a surface layer, and to measure by the same method as the above.

(4) Melt flow index (MF)
I) 230 ° C., 2.16 according to ASTM-D-1238
It was measured under the condition of kg.

(5) Bromine value Measured according to JIS-K2543-1979. It is represented by the number of g of bromine added to the unsaturated component in 100 g of the sample oil.

(6) Heat Shrinkage The heat shrinkage is sampled at a test length of 260 mm and a width of 10 mm, and a mark is placed at a position of 200 mm as the original size (L ₀ ). A load of 3 g was applied to the lower end of the sample, and 12
Heat treatment is performed for 15 minutes in an oven at 0 ° C., after which the length (L ₁ ) marked on the sample is measured. This heat shrinkage (R) is obtained by the following equation. Heat shrinkage (R) (%) = [(L ₀ −L ₁ ) / L ₀ ] × 1
00

(7) Water Vapor Permeability A value measured under the conditions of 40 ° C. and 90% RH in accordance with JIS-Z0208 and expressed in g / m ² · 24 hr / 0.1 mm.

(8) Film thickness The film thickness was measured using a dial gauge type thickness meter (JIS-B7509).

(9) Lamination Thickness The film cross-sectional structure was observed using a field emission scanning electron microscope (FE-SEM), and the thickness was measured.

(10) Gloss (JIS-Z8741, Method 2, 60 ° Mirror Gloss) Gloss at 60 ° reflection is measured using a gloss meter (Model VG107, manufactured by Nippon Denshoku Industries Co., Ltd.). I asked.

(11) Printing processability When gravure printing is performed on a film having a thickness of 20 μm and a length of 1000 m, a printing pitch shift due to shrinkage of the film,
The occurrence of wrinkles and the like of the film was evaluated.

(12) Resistance to Organic Solvents A sample was sampled at a test length of 200 mm and a width of 10 mm, and a mark was placed at a position of 100 mm as the original size (l ₀ ). This sample was immersed in toluene at 25 ° C. for 1 minute, and thereafter, a load of 3 g and 100 g was applied to the lower end of the sample, and 80 g of
Heat treatment in an oven at 1 ° C. for 1 minute, and then measure the length (l ₁ ) marked on the sample. The dimensional change (L) at this time is obtained by the following equation. Dimensional change rate (L) (%) = [(l ₀ −l ₁ ) / l ₀ ] ×
100 Those having a dimensional change (L) of less than ± 2% were evaluated as organic solvent resistance: ○, and those having ± 2% or more were evaluated as organic solvent resistance: x.

(13) Evaporation processability Aluminum was evaporated to a film thickness of about 60 nm with a film thickness of 20 μm and a length of 1000 m at a degree of vacuum of about 1.33 × 10 ⁻⁵ Pa using a vacuum evaporation machine, and was wound. Thereafter, the deposited surface was observed using a field emission scanning electron microscope (FE-SEM), and the occurrence of cracks on the deposited surface was observed.

(14) PVDC coating property PVDC is applied to a film having a thickness of 20 μm and a length of 1000 m.
Was coated in a thickness of 3 μm, dried in an oven at 80 ° C. and wound up. The coated surface was observed using a field emission scanning electron microscope (FE-SEM) to check the occurrence of cracks on the coated surface.

[0049]

The present invention will be described below based on examples and comparative examples. Examples 1 and 2, Comparative Examples 1 and 2 Crystalline polypropylene (PP) (t-1 / 2: 97 sec.)
c, II: 98.7%, MFI: 3.5 g / 10 min), and the extruder was supplied with a layer A resin composition in which a specific hydrogenated nonpolar petroleum resin was mixed with the resin in the ratio shown in Table 1. Melted at a temperature of 240 ° C., while as a laminated resin of layer B, II: 97.
0% crystalline polypropylene is supplied to another extruder (II), melted at a temperature of 260 ° C., and co-extruded into three layers by a multilayer die composed of B layer / A layer / B layer and extruded into a sheet. It was molded, wound around a drum at a draft ratio of 2.0 and at a temperature of 60 ° C., and cooled and solidified into a sheet. The sheet is preheated by passing it through an oven maintained at 140 ° C., then stretched 5.0 times in the longitudinal direction through four rolls maintained at 130 ° C. and provided with a peripheral speed difference, and immediately cooled to 40 ° C. did. Next, the stretched sheet is guided to a tenter and preheated to a temperature of 165 ° C.
Subsequently, the film was stretched 10 times in the width direction at a temperature of 155 ° C., then subjected to a heat treatment at a temperature of 165 ° C. while giving 5% relaxation in the width direction, and then cooled and wound up. The film properties were as shown in Table 2. The film in the range of the present invention has a small heat shrinkage and excellent heat resistance, and also has a small water vapor transmission rate and excellent moisture proofing property, and also has excellent secondary processing properties such as printability and organic solvent resistance and vapor deposition property. It was a film. Further, the film deviating from the scope of the present invention is inferior in either heat resistance or moisture resistance, and is inferior in secondary workability such as printability, organic solvent resistance and vapor deposition, and is an object of the present invention. No film was obtained.

Comparative Examples 3 and 4 In Comparative Examples 3 and 4, the MFI of the crystalline polypropylene of the layer A in Example 1 was 5.0 g / 10 min and 1.0 g, respectively.
A film was produced in exactly the same manner as in Example 1 except that the time was / 10 minutes.

Example 3, Comparative Examples 5 and 6 In Example 3, crystalline polypropylene (t-1 / 2: 1) was used.
12 sec, II: 99.0%) A specific hydrogenated non-polar terpene resin is mixed with the resin in an amount of 15% by weight, supplied to the extruder (I), melted at a temperature of 240 ° C., and guided to a T-type die. A film was produced in exactly the same manner as in Example 1 except that the film was extruded. In Comparative Example 5, t-1 / 2: 225 s was used instead of the crystalline polypropylene of the layer A in Example 1.
ec, II: 97.3% crystalline polypropylene;
In Comparative Example 6, an unhydrogenated polar group (carboxyl group -COO) was used instead of the specific hydrogenated nonpolar petroleum resin of Example 1.
A film was produced in exactly the same manner as in Example 1 except that the petroleum resin having H) was used, and the crystalline polypropylene of the layer B was II: 98.5% crystalline polypropylene.
The film properties were as shown in Table 2. The film in the range of the present invention has a small heat shrinkage and excellent heat resistance, and also has a small water vapor transmission rate and excellent moisture proofing property, and also has excellent secondary processing properties such as printability and organic solvent resistance and vapor deposition property. It was a film. Further, the film deviating from the scope of the present invention is inferior in either heat resistance or moisture resistance, and is inferior in secondary workability such as printability, organic solvent resistance and vapor deposition, and is an object of the present invention. No film was obtained.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

As described above, the heat and moisture resistant film of the present invention is a film in which a specific petroleum resin and / or a specific terpene resin is added to a specific high crystalline polypropylene and mixed. It produces excellent effects. (1) It has a small water vapor transmission rate and excellent moisture resistance, and is suitable for use in packaging, particularly for packaging foods and pharmaceuticals. (2) It has excellent heat resistance and organic solvent resistance required for secondary processing, and has good properties for printing, adhesive tapes, and vapor deposition bases. (3) Since it is excellent in heat resistance and moisture resistance, it can be made thinner and the cost of the packaging material can be reduced.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI // C08L 23/12 C08L 23/12 B29K 23:00 B29K 23:00 55:00 55:00 B29L 7:00 B29L 7:00 9:00 9:00 (56) References JP-A-7-157573 (JP, A) JP-A-58-213037 (JP, A) JP-A-3-255137 (JP, A) JP-A-4-272937 (JP, A) JP-A-8-253633 (JP, A) JP-A-7-76641 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 5/00-5 / 02 C08J 5/12-5/22

Claims (2)

(57) [Claims] 1. Isothermal crystallization time at 125 ° C. of 3.5 minutes or less, isotactic index of 98.5% or more, melt flow index of 2 to 4 g / 10 min. A film in which at least one kind of a petroleum resin substantially free of a polar group and a terpene resin substantially free of a polar group is mixed at 5 to 30% by weight, and heated at 120 ° C. for 15 minutes. Direction heat shrinkage is 5% or less and water vapor transmission rate is 1.0 (g
/ M ² · 24 hr / 0.1 mm) or less. 2. The heat- and moisture-proof film according to claim 1, wherein at least one surface has an isotactic index of 98.
% Or less of a crystalline polypropylene.