JPH0455593B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a polypropylene film having a low water vapor permeability, that is, excellent water vapor barrier properties, and excellent antistatic properties and printability. [Prior art] Polypropylene is mixed with petroleum resin or terpene resin, and the glass transition temperature Tg is 10 to 50°C.
It is already known that a polypropylene film having an excellent water vapor barrier property with a water vapor transmission rate of 0.8 (g/m ² ·day/100 μm) or less can be obtained by using a polypropylene film with -213037). Furthermore, biaxially oriented polypropylene in which a hydrogenated petroleum resin and an amphoteric antistatic agent are added to polypropylene is already known (Japanese Unexamined Patent Publication No. 28076/1983). However, these films still lack sufficient antistatic agents, and suffer from print omissions and print bleeds (whiskers) due to static electricity, resulting in poor printability. In addition, if dust is attached due to static electricity and the film becomes clean, or if it is processed into a bag,
It becomes difficult to open the bag. [Problems to be Solved by the Invention] The present invention solves the above-mentioned drawbacks of polypropylene films having water vapor barrier properties, and improves antistatic properties, blocking resistance, printability, chemical resistance, adhesive coating suitability, and petroleum resins. It is an object of the present invention to provide a polypropylene film that is excellent in suppressing scattering of terpene resins, antistatic agents, and the like. [Means for Solving the Problems] The polypropylene film of the present invention contains 100 parts by weight of polypropylene, 5 to 70 parts by weight of petroleum resin or terpene resin, 0.04 to 0.2 parts by weight of an amphoteric antistatic agent, and a non-ionic antistatic agent. Composed of a mixture of 0.3 to 0.95 parts by weight, the surface resistivity is 1×
10 ¹⁵ Ω or less, and glass transition temperature Tg is 10 to 50℃
It is characterized in that polyolefin layers having a thickness of 20% or less of the total thickness are laminated on both sides of the polypropylene layer. The polypropylene used in the film of the present invention is not particularly limited, but has an isotactic index ( ) of 90% or more and an intrinsic viscosity [η] measured in tetralin of 0.8 to 4.0.
(dl/g), particularly preferably in the range of 1.0 to 2.2 (dl/g). A second component other than propylene, such as ethylene or butene, may be copolymerized, but
Although a homopolymer is preferable in view of the gist of the present invention, it may be copolymerized within a range that does not significantly impede crystallinity. Petroleum resin refers to resins that are directly made from petroleum-based unsaturated hydrocarbons, and includes both those whose main raw materials are cyclopentadiene-based and those whose main raw materials are higher olefin-based hydrocarbons. The petroleum resin used in the present invention has a glass transition temperature Tg of 50
℃ or higher is preferable, and 70℃ or higher is more preferable. Furthermore, the petroleum resin used in the present invention is preferably a hydrogenated petroleum resin to which hydrogen has been added, and in that case, the hydrogenation rate is preferably 80% or more, more preferably 95% or more. As a typical petroleum resin that can be used in the present invention, structural formula: Hydrogenated alicyclic petroleum resins as shown in the following can be exemplified. Terpene resin refers to a resin obtained from terpenes (hydrocarbons with a composition of (C ₅ H ₈ ) _o) . Typical examples of terpenes include pinene, carene, myrcene, ocimene, limonene, terpinolene, terpinene, sabinene, tricyclene, bisabolene, zingiberene, santarene, kanholene, mirene,
Examples include Totaren. The terpene resin used in the present invention is preferably hydrogenated to a hydrogenation rate of 80% or more, more preferably 90% or more, especially alicyclic resins such as hydrogenated β-pinene resin and hydrogenated dipentene resin. Group saturated hydrocarbon resins are preferred. Note that the petroleum resin and terpene resin used in the present invention preferably have substantially no polar groups. The polar group refers to a hydroxyl group, an aldehyde group, a ketone group, a carboxyl group, a halogen group, a sulfon group, and the like. If the polypropylene film has a polar group, its water vapor barrier properties will deteriorate even if the Tg of the polypropylene film is high. As the amphoteric antistatic agent, imidazoline derivatives, carboxylic acid derivatives, etc. are used, and betaine type carboxylic acid derivatives represented by general formula () and amino acid type represented by general formula (2) are particularly preferred. (However, R is a hydrocarbon group having 6 to 22 carbon atoms, preferably a hydrocarbon group having 12 to 22 carbon atoms, and R ₁ to R ₅ are the same or different lower alkylene groups, preferably having 1 to 4 carbon atoms.) lower alkylene groups, X ₁ and X ₂ are
Either CONH ₂ groups, COOH group, or OH group,
Preferably OH group, X ₃ is the same as X ₂ or COONa
Group) These amphoteric antistatic agents are used alone or in mixtures. As the nonionic antistatic agent, well-known ones such as fatty acids, fatty acid amides, ethylene oxide adducts of aliphatic amines, glycerides and the like can be used, but compounds represented by the general formulas () and () are particularly preferred. (However, R ₆ is a linear or branched alkyl group, oxyalkyl group, alkenyl group, or oxyalkenyl group having 12 to 22 carbon atoms, R ₇ is a hydrogen atom, -
(CH ₂ CH ₂ O) _n H (m is 1 or 2) or same as R ₆ ,
( _R8 is an alkyl group or alkenyl group having 11 to 21 carbon atoms) These nonionic antistatic agents may be used alone or as a mixture. The polypropylene film of the present invention is prepared by mixing 100 parts by weight of polypropylene with 5 to 70 parts by weight, preferably 10 to 60 parts by weight of petroleum resin or terpene resin. 70% petroleum resin or terpene resin
If the amount exceeds the weight part, the film becomes brittle and cannot be molded. On the other hand, if it is less than 5 parts by weight, the water vapor barrier properties cannot be improved and the moldability cannot be improved either. In addition, the polypropylene film of the present invention may be a mixture of only one of a petroleum resin and a terpene resin, or may be a mixture of both. The polypropylene film of the present invention is made by mixing polypropylene with petroleum resin or terpene resin, but within the range of not losing the effects of the present invention,
Furthermore, other resins may be mixed. If other resins are added, their amount is preferably less than 20% by weight, more preferably less than 15% by weight. Examples of other resins include polyolefins other than polypropylene. The amount of the amphoteric antistatic agent mixed with 100 parts by weight of polypropylene is 0.04 to 0.2 parts by weight, and the amount of the nonionic antistatic agent is 0.3 to 0.95 parts by weight. If the amphoteric antistatic agent is less than 0.04 parts by weight, the antistatic effect will be insufficient, and the nonionic antistatic agent will
If the amount is less than 0.3 parts by weight, the antistatic effect will be slow to develop. If the amount of the amphoteric antistatic agent or nonionic antistatic agent exceeds the above range, the film will tend to block, become sticky or colored. The proportion of the amphoteric antistatic agent in the total amount of added antistatic agent is preferably 2 to 50% by weight, more preferably 5 to 35% by weight, and even more preferably 10% by weight.
~25% by weight. In the present invention, the effects of adding a mixture of an amphoteric antistatic agent and a nonionic antistatic agent are as follows. In other words, in a polypropylene film layer that contains a petroleum resin or terpene resin that provides water vapor barrier properties, even if only one type of antistatic agent is added, the antistatic agent generally does not interact with the petroleum resin or terpene resin. Because of its high affinity, it is retained by petroleum resins, terpene resins, etc. with large molecular weights, making it difficult for the antistatic agent to bleed out onto the film surface, resulting in poor antistatic properties. On the other hand, in a mixture of an amphoteric antistatic agent and a nonionic antistatic agent, the amphoteric antistatic agent, which has a particularly high affinity with petroleum resins, etc., is held in the petroleum resin, so that the mixture has a relatively low affinity. This further reduces the possibility that the nonionic antistatic agent will be retained in petroleum resin or the like. As a result, the nonionic antistatic agent bleeds out onto the film surface more easily than when it is added alone, and the antistatic properties are further improved. The polypropylene film of the present invention has a glass transition temperature Tg of 10°C or more and 50°C or less, preferably 12°C or more and 50°C or less. If the Tg exceeds 50°C, the moldability will not be improved and it will not be suitable for this purpose. Furthermore, if the Tg is less than 10°C, molding is possible, but the water vapor barrier property does not improve. The polypropylene film of the present invention is at least uniaxially stretched, preferably biaxially stretched, and has a heat shrinkage rate (R) of (R)≧0.
This is the result. Further, the crystallinity is preferably 50% or more, more preferably 60% or more.
The thickness of the film is not particularly limited, but is preferably 5 to 250 μm, more preferably 10 to 100 μm. The polypropylene film of the present invention may further contain other additives as long as the effects of the present invention are not lost. Examples of other additives include known crystal nucleating agents, antioxidants, heat stabilizers, slip agents, antiblocking agents, fillers, viscosity modifiers, and color inhibitors. Next, a method for producing a polypropylene film according to the present invention will be described, but the method is not limited to the following method. Add petroleum resin or terpene resin to polypropylene, pelletize it (resin temperature should be at the following temperature), add an antistatic agent, and increase the resin temperature to a temperature not exceeding 240℃, preferably a maximum of 180 to 220℃. After melting and uniformly mixing at a temperature, the polypropylene film of the present invention is obtained by discharging from a die and casting on a cooling drum. If the resin temperature exceeds 240° C., not only will it not be possible to obtain a film with the excellent properties aimed at by the present invention, but also the resin will thermally decompose or scatter, which is not preferable. In addition, the surface temperature of the cooling drum varies depending on the relationship with subsequent processes, but
120°C is preferable, and 70-110°C is more preferable. In addition, an even more excellent polypropylene film of the present invention can be obtained by uniaxially, biaxially, or multiaxially oriented the above-cast film, or by subjecting it to heat treatment. In this case, the method for providing orientation may be any known method,
For example, roll stretching, rolling, tenter stretching, disk stretching, belt stretching, or a combination thereof can be used. At this time, it is preferable to make the orientation as highly oriented as possible; for example, in the case of sequential biaxial stretching, the initial longitudinal stretching ratio is 4 to 10 times,
The next transverse stretching ratio is preferably as high as 8 to 18 times. That is, in the step of imparting orientation, it is desirable to increase the degree of orientation of crystal and amorphous chains, tension the molecular chains, and set the refractive index in the thickness direction to 1.495 or less, preferably 1.494 or less. Furthermore, it is also desirable to select orientation conditions such as high-temperature stretching conditions such that the degree of crystallinity is as high as possible, and it is desirable that the degree of crystallinity be 50% or more, preferably 60% or more. Furthermore, by laminating on both sides of the polypropylene film of the present invention a polyolefin layer to which no petroleum resin or terpene resin is added, especially a polypropylene layer having a thickness of 20% or less of the total thickness, chemical resistance can be improved. This not only significantly improves printability and adhesive coating suitability, but also suppresses scattering of petroleum resins or terpene resins, antistatic agents, and other additives during extrusion, improving productivity. It is highly effective in improving the working environment. Additionally, inorganic particles (e.g.
Zeolite, kaolin, silica, etc.) from 0.09 to
It is more preferable to add 0.5 wt%, more preferably 0.11 to 0.3 wt%, from the viewpoint of blocking resistance and slipperiness during high-temperature processing. Furthermore, the polypropylene film of the present invention is subjected to a corona discharge treatment under air, carbon dioxide gas, or nitrogen gas to increase the wettability index to about 36 dyne/cm or more, thereby promoting the development of antistatic properties and improving surface adhesion. Better to improve. Regarding the measurement method of the terms used in the present invention, the following is
explain. (1) Water vapor transmission rate...40℃, according to JIS Z-0208,
Value measured at 90%RH, g/ ^m2・day/100μm
Expressed in units. (2) Intrinsic viscosity [η]…According to ASTM D1601,
Measured in Tetralin and expressed in dl/g. (3) Surface specific resistance: This value is 18.8 times the value measured by applying a potential between the guard electrode and the main electrode and grounding the counter electrode using an electrode that measures volume specific resistance according to JIS-C2330. (4) Glass transition temperature: 10 mg of the sample was set in a scanning calorimeter DSC-type (manufactured by Perkin Elmer), and the temperature was increased at a rate of 40°C/min under a nitrogen stream.
Start at 20℃, draw a thermograph, and calculate the arithmetic mean value of the temperature at which the endothermic peak deviates from the baseline and the temperature at which it returns.
Let it be Tg. This method is used even if the sample is a composite film. (5) Wetting index...Measured in accordance with JIS-K6768. (6) Blocking shear force (evaluation of blocking resistance)...A sample film of 3 cm width x 10 cm length was
After stacking them over 1 cm and leaving them in an atmosphere of 40℃ and 80%RH for 24 hours under a load of 40g/ ^cm2 ,
Measure the force required for shear peeling using a tensile tester. The smaller the value, the better the blocking resistance. (7) Printability evaluation: A pattern was printed using nitrocellulose ink using a gravure method, and the printing appearance (ink omission due to static electricity, ink flow) was evaluated. ○: Good △: Fairly good ×: Bad (8) Slip coefficient: Two samples that have been conditioned for 24 hours in a room at 20℃ and 65% RH are placed on a heated plate with opposite sides stacked on top of each other. on that film
A sample was moved at a speed of 150 mm/min with a load of 200 g on it, and its resistance value was read and expressed as a calculated value of resistance value (g)/200 g. [Example] Examples 1 to 3 and Comparative Examples 1 to 4 As the polypropylene, "Mitsui Noblen" J4H (intrinsic viscosity [η] = 1.35, isotactic index = 98%) manufactured by Mitsui Toatsu Co., Ltd. was used. As the petroleum resin, non-polar "Escoretsu" 5320 manufactured by Etsuso Chemical Co., Ltd. was used. To 100 parts by weight of the polypropylene, 25 parts by weight of "ESCOLETS" 5320 was uniformly blended and pelletized. An amphoteric antistatic agent and a nonionic antistatic agent shown below were added to the pellets as shown in Table 1 to obtain a raw material (). Amphoteric antistatic agent; Nonionic antistatic agent; C ₁₈ H ₃₇ −N(CH ₂ CH ₂ OH) ₂ + stearic acid monoglyceride (ratio 5:
1) Furthermore, as the raw material (), [η] = 1.0, =
95% ultra-low viscosity polypropylene (zeolite 0.12
% addition), feed the raw materials () and raw materials) to separate extruders, and process ()/()/().
A three-layer laminated film consisting of the following was coextruded at 210°C and then cast onto a casting drum kept at 85°C to obtain an unstretched film. The film was immediately introduced into a longitudinal stretching roll maintained at 128°C, stretched 7 times in the longitudinal direction, and then heated to 158°C.
Stretched 10 times in the width direction in a tenter heated to
Heat treatment was carried out at 161° C. for 10 seconds while allowing 5% relaxation in the lateral direction to obtain a biaxially oriented polypropylene film consisting of a three-layer laminate. Both sides of the film were subjected to corona discharge treatment to determine the wettability index.
It was set to 38dyne/cm. The thickness of the film is ()
The layer is 1μm, the () layer is 23μm, and the total is 25μm.
It was hot. The properties of the obtained film are shown in Table 1. As is clear from Table 1, the films of Examples 1 to 3 to which appropriate amounts of amphoteric antistatic agent and nonionic antistatic agent were added had low surface resistivity, no ink shedding, no ink flow, The film had excellent printability, excellent blocking resistance, and low water vapor permeability. Comparative Example 1 in which only an amphoteric antistatic agent was added, Comparative Example 2 in which only a nonionic antistatic agent was added, and Comparative Example in which both types of antistatic agents were added, but the amount added was outside the range of the present invention. In Example 4, the surface resistivity was high, the printability was poor, and ink omission occurred. Furthermore, Comparative Example 4 was a film with high blocking.

[Table] Example 4 and Comparative Example 5 In Example 1, the petroleum resin "Escoretsu"
Example 1 was carried out in the same manner as in Example 1, except that instead of 5320, another petroleum resin or terpene resin shown in Table 2 was used. The properties of the obtained film are shown in Table 2. As is clear from the results in Table 2, the film
When Tg decreases, the surface resistivity, blocking resistance, and printability are satisfactory, but the water vapor barrier performance deteriorates.

[Table] Example 5 The same procedure as in Example 1 was carried out except that zeolite was not added to the raw material (). The obtained film had almost the same water vapor permeability, surface resistivity, and printability as the film of Example 1. However, as shown in Table 3, the film of Example 1 was superior in terms of blocking shear force. Further, the film of Example 1 was excellent in slippage at high temperatures.

〔Effect of the invention〕

The polypropylene film of the present invention has the following excellent properties. (1) Shows excellent barrier properties with a water vapor permeability of 0.8 (g/m ² ·day/100 μm) or less. (2) No printing missing or running due to static electricity;
Shows excellent printability. (3) The film is free from dust and has a clean appearance. (4) The film has excellent blocking resistance and slip properties. (5) The film has excellent chemical resistance. (6) The film has excellent adhesive coating properties. (7) The film is excellent in suppressing scattering of petroleum resins, terpene resins, antistatic agents, etc.

Claims (1)

[Claims] 1 100 parts by weight of polypropylene, 5 to 70 parts by weight of petroleum resin or terpene resin, 0.04 parts by weight of amphoteric antistatic agent
~0.2 parts by weight and 0.3 to 0.95 parts by weight of nonionic antistatic agent
It has a composition in which parts by weight are mixed, has a surface resistivity of 1×10 ¹⁵ Ω or less, and has a glass transition temperature Tg.
A polypropylene film characterized in that a polyolefin layer having a thickness of 20% or less of the total thickness is laminated on both sides of a polypropylene layer having a temperature of 10 to 50°C.