JP3384460B2 - Polypropylene film with improved slip properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene film, and more particularly to a polypropylene film having excellent slip properties.

[0002]

2. Description of the Related Art Polypropylene, especially a propylene-ethylene random copolymer film, is excellent in transparency and has a certain degree of heat sealability, so that it can be widely used for various packaging. Used. However, polypropylene film is inferior in slip property, especially when stored at a high temperature of 45 ° C. or higher, or when subjected to heat treatment, the slip property is reduced, and when performing secondary processing such as printing and laminating step In addition, there is a problem that trouble is likely to occur when packaging.

Accordingly, a polypropylene film having improved slip properties is obtained by melt-extrusion from a composition comprising 0.07 to 1.0 part by weight of a lubricant having a melting point of 100 to 125 ° C. per 100 parts by weight of crystalline polypropylene. [A] with a melting point of 100-125 ° C and a lubricant with a melting point of 70-90 ° C with respect to 100 parts by weight of the film and crystalline polypropylene
(B) and a film obtained by melt extrusion from a composition added so that the total amount is 0.05 to 1.0 part by weight (JP-A-62-265335 and JP-A-62-265336). ).

[0004] The above film has an initial slip property of 0.7 or less and a slip property after heat treatment at 60 ° C of 1.0 or less, and is excellent in slip property. However, the film does not have sufficient initial slip properties and slip properties after heat treatment, after storage at high temperature and after lamination, and there is a problem that the initial slip properties are not particularly good. Therefore, in order to impart sufficient lubricity to the above-mentioned film immediately after film formation, after heat treatment, after high-temperature storage, and after lamination, it is necessary to set the blending amount of the lubricant at a relatively large amount. There are problems such as bleed-out and reduction in laminate strength.

Accordingly, an object of the present invention is to provide a polypropylene film exhibiting excellent slip properties immediately after film formation, after heat treatment, after high-temperature storage and after lamination.

[0006]

Means for Solving the Problems As a result of intensive studies in view of the above-mentioned objects, the present inventors have found that when high-density polyethylene is blended with a propylene-ethylene random copolymer, the compatibility and surface transfer rate of the slip agent change. However, it has been found that the degree of the change differs depending on the type of the slip agent. In addition, the present inventors have added a slip agent having a melting point of 70 to 90 ° C to a resin component obtained by mixing a predetermined amount of high-density polyethylene with a propylene-ethylene random copolymer,
When two types of slip agents having a melting point of 125 ° C. are added in a predetermined amount, the timing of leaching of both slip agents to the surface is determined by the initial slip property, the slip after heat treatment, after high temperature storage and after lamination. A surprising effect of significantly improving all of the properties was found. The present invention has been made based on the above findings.

That is, the polypropylene film of the present invention comprises 100 parts by weight of a resin component comprising 99 to 10% by weight of a propylene-ethylene random copolymer having an ethylene content of 2 to 10% by weight and 1 to 10% by weight of a high-density polyethylene. On the other hand, a slip agent (a) having a melting point of 70 to 90 ° C.
Parts by weight of a slip agent having a melting point of 100 to 125 ° C (b)
It is characterized by comprising a composition containing 0.03 to 0.20 parts by weight.

[0008] The present invention will be described in detail below. The polypropylene film of the present invention is a propylene-ethylene random copolymer having an ethylene content of 2 to 10% by weight, and a slip agent (a) having a melting point of 70 to 90 ° C with respect to a resin component consisting of high-density polyethylene. And a slip agent (b) having a melting point of 100 to 125 ° C.

Hereinafter, the components of the polypropylene film of the present invention will be described in detail. Propylene-ethylene random copolymer Propylene-ethylene random copolymer is obtained by copolymerizing propylene and ethylene in the coexistence. Ethylene is 2 to 10% by weight, preferably 3 to 8% by weight. It is a copolymer containing. The melt flow rate (MFR, 230 ° C., 2.16 kg load) of the above propylene-ethylene random copolymer is preferably 4 to 30 g / 10 min, particularly 6 to 15 g / 10 min.
Minutes are preferred.

High Density Polyethylene High density polyethylene (HDPE) is derived from ethylene.
Is the main polymer component and has a density of 0.940 g / cm
³ or more polymers. In the present invention, the density
There 0.945 ~0.960 g / cm ³ of density polyethylene (HDPE)
It is preferred to use. High density polyethylene (HDP
E) melt index (MI, 190 ° C, 2.16kg load)
Is preferably 5 to 30 g / 10 minutes, and particularly preferably 8 to 20 g / 10 minutes. High-density polyethylene (HDPE) can be obtained, for example, by polymerizing ethylene by a low-pressure method in the presence of a Ziegler catalyst or the like.

The mixing ratio of the resin component is 100 to 100% by weight of the total of the propylene-ethylene random copolymer and the high-density polyethylene, and the mixing ratio of the propylene-ethylene random copolymer is 99 to 90%. %, Preferably 98 to 92% by weight, and high density polyethylene 1 to 10% by weight, preferably 2%.
８8% by weight. If the high-density polyethylene is less than 1% by weight (the propylene-ethylene random copolymer exceeds 99% by weight), the slip property immediately after film formation or the slip property after heat treatment or lamination is reduced. Exceeds 10% by weight (less than 90% by weight of the propylene-ethylene random copolymer), the transparency, tear strength and impact strength of the film decrease.

Slip agent (a) The slip agent (a) has a melting point of 70 to 90 ° C. If the melting point of the slip agent (a) is less than 70 ° C., the slip property at high temperatures is significantly reduced, and if it exceeds 90 ° C., the initial slip property is significantly reduced. The slip agent having the melting point (a), it is possible to use unsaturated fatty acid amides and their derivatives C ₁₈ -C _22. Specifically, oleic acid amide, erucic acid amide, elaidic acid amide,
N-stearyl erucamide and derivatives thereof. Of these, erucamide and oleamide are particularly preferred. The above slip agents may be used alone or in combination.

The compounding amount of the slip agent (a) is determined based on the resin component.
The amount is 0.03 to 0.25 parts by weight, preferably 0.03 to 0.20 parts by weight, based on 100 parts by weight of (propylene-ethylene random copolymer + high-density polyethylene) in total. Slip agent
If the compounding amount of (a) is less than 0.03 parts by weight, the effect of improving the slip property by the compounding is not sufficient, and if it exceeds 0.25 parts by weight, a large amount of slip agent is bleached out to the film surface, and secondary processing and It becomes difficult to use for packaging and the like.

[0014] Slip agents (b) a slip agent (b) are those having a melting point of 100 to 12 5 ° C.. If the melting point of the slip agent (b) is less than 100 ° C., the slip property at a high temperature is significantly reduced, and if it exceeds 125 ° C., it becomes difficult to develop the slip property. As the slip agent (b) having the above melting point, C ₁₆ -C ₂₂ saturated fatty acid amides and derivatives thereof can be used. Specific examples include stearic acid amide, palmitic acid amide, behenic acid amide, N- (2-hydroxymethyl) stearic acid amide, and derivatives thereof. Of these, stearic acid amide and behenic acid amide are particularly preferred. The above slip agents may be used alone or in combination.

The compounding amount of the slip agent (b) is determined based on the resin component.
The amount is 0.03 to 0.20 parts by weight, preferably 0.03 to 0.16 parts by weight, based on 100 parts by weight of (propylene-ethylene random copolymer + high-density polyethylene) in total. Slip agent
If the compounding amount of (b) is less than 0.03 parts by weight, the effect of improving the slip property by the compounding is not sufficient, and if it exceeds 0.20 parts by weight, a large amount of the slip agent (b) is bleached out to the film surface, and It becomes difficult to use it for the next processing and packaging.

In addition to the above-described components, other additives such as a heat stabilizer, an antioxidant, a light stabilizer, a flame retardant, and an antistatic agent are added for the purpose of modifying the components. be able to.

The thickness of the polypropylene film of the present invention is preferably from 15 to 60 μm, and particularly preferably from 20 to 40 μm. If the film thickness is less than 15 μm,
Film formation becomes difficult, and if it exceeds 60 μm, the heat sealability of the film is undesirably reduced.

The polypropylene film of the present invention comprising the above-mentioned components can be produced by a usual film forming method such as a T-die method and an inflation method. For example, the polypropylene film is produced by the following cast film method. Is preferred.

First, a propylene-ethylene random copolymer, high-density polyethylene, a slip agent (a) and a slip agent (b) are melt-kneaded at 220 to 250 ° C.

Next, a composition melt-kneaded at 220 to 250 ° C. is extruded from a flat T-die so as to have a desired film thickness, and is formed by a cast film method.

The above-mentioned polypropylene film of the present invention can be subjected to a heat treatment (aging) at 30 to 50 ° C. and 12 to 24 hours as needed.

The polypropylene film of the present invention is prepared by applying a urethane-based adhesive, an acrylic-based adhesive or the like to one surface, and biaxially stretching a polypropylene film (OPP film) or a polyethylene terephthalate film (PET) by a dry lamination method or the like. Film). The adhesive may be applied to a film such as a biaxially stretched polypropylene film (OPP film) or a polyethylene terephthalate film (PET film).

Such a polypropylene film of the present invention has a surface friction coefficient (JIS 7218) of 1.
0 or less, preferably 0.9 to 0.7, and the friction coefficient after heat treatment such as aging is 0.4 or less, preferably 0.15 to 0.1.
3 In addition, the value of the coefficient of friction is generally
It is preferably 1.0 or less, and after the heat treatment, it is preferably 0.4 or less because secondary processing and packaging are performed. The polypropylene film of the present invention has a sufficient slip property satisfying the above requirements.

[0024]

The polypropylene film of the present invention is obtained by adding a slip agent having a melting point of 70 to 90 ° C to a resin component obtained by mixing a predetermined amount of high density polyethylene with a propylene-ethylene random copolymer, and a slip agent having a melting point of 100 to 125 ° C. Since the composition is formed by adding two kinds of slip agents having a melting point in a predetermined amount, the initial slip property and the slip property after heat treatment, after high-temperature storage and after lamination are extremely improved.

Although the reason why such an effect is obtained is not necessarily clear, by adding high-density polyethylene to the propylene-ethylene random copolymer, the resin components of the slip agents (a) and (b) can be reduced. The compatibility and the surface transfer rate change, and accordingly, the time required for each slip agent to exhibit the slip property, the effect of improving the slip property, the durability and the like change. In the present invention, the compounding ratio of the high-density polyethylene, the slip agent (a)
The slip agent (b) exhibits a slip property immediately after film formation, and when the slip property starts to decrease, the slip agent (b) is in a range such that it exhibits a good slip property. Moreover, the slip agent (b) has excellent heat resistance. As a result, the slip properties of the slip agents (a) and (b) are optimal for exhibiting the slip properties required in each case immediately after film formation, after heat treatment, after high-temperature storage, and after lamination. It is considered that this is because

[0026]

The present invention will be described in more detail with reference to the following examples. The following resins and slip agents were used as raw materials. [1] Propylene-ethylene random copolymer RPP: [Melt flow rate (MFR, 230 ° C., 2.16 kg load) 9 g / 10 min, ethylene content 3.6% by weight] [2] High-density polyethylene HDPE: [Melt index ( MI, 190 ° C, 2.16kg
Load) 12 g / 10 min, density 0.958 g / cm ³ ] [3] Slip agent (a) Erucamide: EA [melting point 83.5 ° C] Oleic amide: OA [melting point 73 ° C] [4] Slip agent (b) Behenic acid amide: BA [melting point 112.0 ° C] Stearic acid amide: SA [melting point 102 ° C]

Examples 1-4 and Comparative Examples 1-3 Propylene-ethylene random copolymer (RPP), high density polyethylene (HDPE), slip agent (a) and slip agent (b) As shown in the table, the mixture was melt-kneaded at 240 ° C and 100 rpm with a 40mmφ extruder, and extruded at a temperature of 240 ° C with an extrusion temperature of 25 ° C and a take-up speed of 30m / min using a T-die molding machine. Thus, a polypropylene film having a thickness of 25 μm was obtained.

The slip property (coefficient of friction) of the obtained polypropylene film was measured and the bleed-out property was evaluated. The results are shown in Table 2.

Next, this film was subjected to a heat treatment (aging) at 40 ° C. for 24 hours, and thereafter, the slip property was measured and the bleed-out property was evaluated. The results are shown in Table 2.

Further, a biaxially oriented polypropylene film (OPP film) coated with a urethane-based adhesive was dry-laminated at 50 ° C. on one surface of the aged film. Subsequently, a heat treatment was performed at 40 ° C. for 72 hours, and thereafter, the slip property of the lamination film on the polypropylene film side and the evaluation of the lamination adhesive strength were evaluated. The results are shown in Table 2.

Table 1 Composition (parts by weight) Example 1 Example 2 Example 3 Example 4 RPP 95 95 97 95 HDPE 55 35 5 Slip agent (a) EA 0.05 0.03 0.05 -OA---0.04 slip Agent (b) BA 0.05 0.06 0.06-SA---0.06

Table 1 (continued) Composition (parts by weight) Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 RPP 100 95 95 100 100 HDPE -55-- Slip Agent (a) EA 0.05 0.10-0.30- Slip agent (b) BA 0.05-0.10-0.30

Table 2 Physical properties Example 1 Example 2 Example 3 Example 4 Slip property ⁽¹⁾ Immediately after film formation 0.81 0.88 0.86 0.87 After heat treatment 0.18 0.20 0.25 0.28 After dry lamination + heat treatment 0.17 0.14 0.23 0.37 bleed Out property evaluation ⁽²⁾ Transparency immediately after film formation 2.4 2.5 2.5 2.5 Whitening degree after heat treatment +0.2 +0.1 +0.2 +0.3 Evaluation of lamination adhesive strength after dry lamination ⁽³⁾ 250 270 245 245

Table 2 (continued) Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Slip property ⁽¹⁾ Immediately after film formation 1.14 0.63 1.17 0.35 0.61 After heat treatment 0.30 0.10 0.23 0.06 0.35 Dry lamination + heating After processing 0.28 0.73 0.12 0.10 0.40 Evaluation of bleed-out characteristics ⁽²⁾ Transparency immediately after film formation 2.5 2.6 2.6 2.8 2.7 Degree of whitening after heat treatment -0.2 +0.5 +1.0 +2.5 +2.7 After dry lamination Evaluation of laminating adhesive strength ⁽³⁾ 250 260 240 80 55

(1) Slip property: According to JIS 7218, friction coefficient test, immediately after production, after heat treatment at 40 ° C. for 24 hours,
The film is biaxially oriented polypropylene film (OPP)
Film) and then heat-treated at 40 ° C for 72 hours. (2) Evaluation of bleed-out characteristics: Bleed-out characteristics were evaluated based on changes in the transparency of the film. In other words, first, the transparency of the film immediately after film formation conforms to JIS K7105.
(Haze) was measured, then the haze after the heat treatment was measured, and the difference between the haze value immediately after the film formation and the haze value after the heat treatment was indicated as the degree of whitening. (3) Evaluation of lamination adhesive strength after dry lamination:
90 ° at a peeling speed of 500 m / min using an autograph tensile tester for the film (15 mm width) after dry lamination
Measure the strength when peeled (unit: g / 15 mm width).

As is clear from Table 2, the polypropylene film of the present invention had good bleed-out characteristics immediately after film formation and good lamination adhesive strength after dry lamination. This is because the coefficient of friction immediately after film formation is
This is considered to be because the coefficient of friction after heat treatment and the coefficient of friction after dry lamination and heat treatment were all 0.4 or less. In contrast, the polypropylene films of Comparative Example 1 and Comparative Example 3 had a coefficient of friction immediately after film formation.
Since it exceeds 1.0, the processability during film formation is inferior, and the polypropylene film of Comparative Example 2 has a coefficient of friction after dry lamination of more than 0.4. It was easy to occur and was inferior in practicality. Furthermore, the polypropylene films of Comparative Examples 4 and 5 were inferior in bleed-out characteristics, had a high degree of whitening, and had a lamination adhesive strength of 100 g / 15 mm or less in width, making them difficult to use.

[0037]

As described in detail above, the polypropylene film of the present invention has a temperature of 70 to 90 ° C. with respect to a resin component obtained by mixing a predetermined amount of high-density polyethylene with a propylene-ethylene random copolymer. Agent having a melting point of
(a) and a slip agent (b) having a melting point of 100 to 125 ° C., which is composed of a predetermined amount, so that it has extremely excellent slip properties immediately after film formation, after high-temperature storage, and even after dry lamination. Demonstrate. Such a polypropylene film of the present invention is suitable for various types of packaging.

Continuation of the front page (51) Int.Cl. ⁷ identification code FI C08L 23:04) (58) Investigated field (Int.Cl. ⁷ , DB name) C08L 23/16 C08J 5/18 CES B32B 27/32 B32B 27/36

Claims (7)

(57) [Claims] 1. A resin component 100 comprising 99 to 90% by weight of a propylene-ethylene random copolymer having an ethylene content of 2 to 10% by weight and 1 to 10% by weight of a high-density polyethylene.
Slip agent with a melting point of 70-90 ° C based on parts by weight
A polypropylene film comprising a composition containing (a) 0.03 to 0.25 parts by weight and a slip agent having a melting point of 100 to 125 ° C (b) 0.03 to 0.20 parts by weight. 2. The polypropylene fill according to claim 1,
Wherein the slip agent (a) is a C ₁₈ -C ₂₂ unsaturated
Selected from the group consisting of fatty acid amides and their derivatives
Even without a kind, and the slip agent (b) is C ₁₆ ~
From the group consisting of saturated fatty acid amides and their derivatives C ₂₂
A polyp characterized by being at least one selected
Lopylene film. 3. Polypropylene according to claim 1 or 2
In a film, the high-density polyethylene melt
Index is 5 ~ 30g / 10min
Polypropylene film. 4. An ethylene content of 2 to 10% by weight,
And a melt flow rate of 4 to 30 g / 10 minutes
99-90% by weight of len-ethylene random copolymer, high density
Resin component consisting of 1 to 10% by weight polyethylene
Slip agent having a melting point of 70 to 90 ° C based on parts by weight
(a) having a melting point of 100 to 125 ° C with 0.03 to 0.25 parts by weight
Composition containing slip agent (b) 0.03 to 0.20 parts by weight
A polypropylene resin composition comprising: 5. The polypropylene resin set according to claim 4,
In the composition, the slip agent (a) is a C ₁₈ -C ₂₂ unsaturated
Selected from the group consisting of fatty acid amides and their derivatives
Even without a kind, and the slip agent (b) is C ₁₆ ~
From the group consisting of saturated fatty acid amides and their derivatives C ₂₂
A polyp characterized by being at least one selected
Lopylene resin composition. 6. Polypropylene according to claim 4 or 5
In a resin composition, a melt of the high-density polyethylene
The index is 5 ~ 30g / 10min
Polypropylene resin composition. 7. A biaxially stretched polypropylene film or polyester.
Riechirentere phthalate film to claims 1-3 Neu
The polypropylene film described in somewhere is laminated
A lamination film characterized by being laminated.