JPH0533143B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention particularly relates to a propylene copolymer laminated film that has significantly improved slipperiness after high-temperature aging of a multilayer film, and has good transparency and heat sealability. [Prior Art] In general, unstretched polypropylene films are made of polypropylene, which has excellent properties such as transparency, heat resistance, moisture resistance, mechanical properties, and gloss, as well as excellent smoothness. Because of this, it is widely used in the packaging field as a single-layer film or multi-layer film. This multilayer film includes a film in which a propylene copolymer resin is laminated as a heat seal layer on the surface of a polypropylene base material using a coextrusion method, and a polypropylene base film and a propylene copolymer resin surface layer film are laminated by melt extrusion of polyethylene. There are films in which layers are laminated, and films in which biaxially stretched polypropylene or nylon is used as a base film and a propylene copolymer resin film is dry laminated using an adhesive. The first quality required for such an unstretched polypropylene film is that it has low-temperature heat sealability. With the recent increase in packaging speed due to high-speed automatic packaging, sealing temperature control has become particularly important when laminating with highly heat-shrinkable films. The second reason is that the film is highly slippery. If the film's slipperiness is insufficient, it not only slows down the processing speed in high-order processing processes such as bag making, but also makes it difficult to handle the processed product due to poor opening of the bag, which greatly impairs work efficiency. Therefore, slipperiness is one of the important required properties. In addition, good anti-blocking properties and no deterioration in transparency due to changes over time are listed. Conventionally, known methods for imparting slipperiness to propylene polymers for films include adding organic fatty acid amides such as stearic acid amide and erucic acid amide, and adding inorganic compounds such as silica and talc. ing. By adding these compounds, the slipperiness of the film is greatly improved, often reaching a practical level. [Problems to be Solved by the Invention] However, poor slip properties often occur in multilayer films, especially dry laminated films. That is, in the case of dry lamination, for example, a solution containing an adhesive is applied to a base material layer such as a biaxially oriented polypropylene film, and after drying the solvent, an unoriented propylene polymer film is adhered to the coated surface. A multilayer film is manufactured using the following steps. At this time, it is preferable to perform aging at a high temperature to shorten drying time and increase adhesive strength.
Since aging significantly deteriorates slipperiness, the current temperature must be limited to 35°C or less. Therefore, improvement in this respect is strongly desired. [Means for Solving the Problems] The present invention was made based on the discovery that the above-mentioned drawbacks can be solved by using a composition for films in which a specific lubricant is blended in a fixed amount with a specific propylene copolymer resin. It is something that That is, the present invention provides ``100 parts by weight of a propylene-α-olefin copolymer resin having a melting peak temperature of 145°C or less by the DSC method, and 0.01 to 0.5 parts by weight of an aliphatic amide having a solubility in 100 g of ethyl acetate of 0.8 g or less. This is a propylene copolymer laminate film characterized in that an unstretched film made of the blended composition is laminated with a base film via an adhesive layer. [Function] The propylene-α olefin copolymer used in the present invention The polymer resin has a melting peak temperature of 145 by the DSC method.
℃ or below. Here, α-olefin is
Ethyl, butene-1, pentene-1, 4-methylpentene-1, hexene-1, octene-1, etc., with a carbon number of 10 or less, and one or more types as a copolymerization component with the majority of the weight of propylene. can be used. Preferred copolymer resins include a propylene-ethylene random copolymer and a propylene-ethylene-butene-1 random copolymer, which have appropriate heat sealability. The melt flow rate (MFR) of these copolymer resins may be as long as they can be molded, but usually 0.5 to 100 g/10 minutes, especially 1 to 50 g/10 minutes,
Particularly preferred is 3 to 30 g/10 minutes. In addition, those whose melting peak temperature exceeds 145℃,
Low-temperature heat sealability is poor and it cannot be put to practical use. Next, the fatty acid amide used in the present invention has a solubility of 0.8 g or less in 100 g of ethyl acetate. Here, solubility is measured by the following method. That is, put 100g of ethyl acetate in an Erlenmeyer flask,
After adding 20g of amide compound, cover with a rubber stopper and heat at 30℃.
The mixture was immersed in a constant temperature bath for 3 hours, and shaken during that time. Thereafter, the excess amide compound remaining undissolved was separated, and the liquid was concentrated, and the weight of the residue was defined as the solubility. Aliphatic amides with solubility exceeding 0.8 g determined by the above measurement method may provide sufficient film slipperiness, but when high temperature aging is performed after dry lamination, the slipperiness becomes markedly poor, resulting in a product that cannot withstand practical use. That cannot be true. Specific examples of the aliphatic amide used in the present invention include behenic acid amide, N-stearyl stearic acid amide, N-stearyl behenic acid amide, N-oleyl behenic acid amide, and N-stearyl erucic acid amide. preferable. especially,
N-oleylbehenic acid amide and N-stearyl erucic acid amide are preferred because they have stable film slipperiness and slipperiness after high-temperature aging.
In addition, it is not limited to these compounds,
In addition to using only these aliphatic amides, a mixture of two or three or more other aliphatic amides may be used, and the effects of the present invention can be achieved as long as the solubility is 0.8 g or less. The amount of fatty acid amide used in the present invention is 0.01 to 0.5 parts by weight based on 100 parts by weight of the above-mentioned propylene-α-olefin copolymer. If the amount of fatty acid amide is less than 0.01 parts by weight, it is impossible to impart slipperiness to the film, and if it exceeds 0.5 parts by weight, although sufficient slipperiness is provided, the bleeding of the fatty acid amide may cause the film to become slippery. This is not preferable because it impairs transparency. The amount to be added may be set within the above range depending on the use of the film and the type of the propylene copolymer. As for the addition method, mixing may be performed for a predetermined time using a commonly used mixer such as a Henschel mixer, a V blender, or a ribbon blender. Usually, the composition is prepared using a general kneading machine prior to film forming. In addition, the blending ratio of the fatty acid amide may be determined by blending the desired amount at once, or by blending the fatty acid amide in a larger amount than the desired amount and diluting it with a propylene copolymer during film molding to form a so-called master batch. Furthermore, in the present invention, in addition to the above-mentioned essential components, stabilizers used for ordinary polyolefins, processing aids, and inorganic compounds such as silica and talc can be added for the purpose of improving the blocking and slipping properties of the film. . As a film forming method, conventional forming methods are applied, and the T-die method is generally used. Suitable base films used for lamination include biaxially oriented polypropylene films, biaxially oriented nylon films, biaxially oriented polyester films, etc. as shown in Examples below. Examples of the lamination method include a method of laminating a melt-extruded layer of polyethylene or the like as an adhesive layer, and a method of dry laminating using a commercially available adhesive.
The present invention exhibits more remarkable effects in a lamination method using dry lamination. In addition, in the dry lie meat method, adhesive is applied to the base film using a roll such as a gravure roll, and after drying the solvent in a drying oven,
A common method is to bond unstretched films together on a heated metal roll. At this time, the adhesive used is, for example, vinyl, acrylic, polyamide, epoxy, urethane, or the like. [Example] Evaluation method (1) Transparency: Measured by stacking four films in accordance with ASTM-D1003. (2) Blocking property: Two films were stacked so that the contact area was 10 ^m2 , sandwiched between two glass plates, and a load of 50 g/ ^cm2 was applied, left at 40°C for 8 days, and then subjected to a shovel type test. Machine tensile speed 500
Evaluated by the maximum load when peeled off at mm/min. (3) Slip property: Compliant with ASTM-D1894 static friction coefficient measurement method. (4) Melting peak by DSC method: Using PerkinElmer DSC, take a sample amount of 5.0 mg,
After holding at 190°C for 3 minutes, crystallize at a cooling rate of 10°C/min to 50°C, and then melt at a heating rate of 10°C/min. Evaluate by the melting peak temperature. (5) Heat-sealability: Using a 5mm x 200mm heat-sealing bar, cut out a 15mm-wide sample from the sample that was heat-sealed under the conditions of heat-sealing pressure 1Kg/cm ² and heat-sealing time 1.0 seconds at each set temperature. Peel it off at a pulling speed of 500mm/min using a shovel type testing machine, and read the maximum load for evaluation. Examples 1 to 5, Comparative Examples 1 to 4 Propylene-ethylene random copolymer (ethylene content 4.5% by weight, melting peak temperature 137.5°C,
MFR6.0g/10min) 100 parts by weight, 2,6-di-t-butyl-p-cresol as an antioxidant
0.15 parts by weight of hydrochloric acid, 0.05 parts by weight of calcium stearate as a capping agent, 0.25 parts by weight of synthetic silica as an antiblocking agent, and 0.1 parts by weight of various fatty acid amides shown in Table 1 were mixed and pelletized. The obtained pellets were extruded through a 35 mm diameter T-die at a molding temperature of 250° C. to produce an unstretched single-layer film with a thickness of 30 μm. One side of this film was subjected to corona discharge treatment at a treatment rate of 50 W·min/m ² and aged for 2 days in an atmosphere at 40°C. Next, a 40μ biaxially stretched polypropylene film was used as the base layer film, and a urethane-based
After applying the liquid-reactive adhesive, dry lamination was performed with the corona discharge treated surface of the single-layer film obtained earlier, and aging was performed in an atmosphere at 45° C. for 6 days. Slip properties were measured on the single-layer film before dry lamination, which was aged at 40°C for 2 days, and the multilayer film, which was dried at 40°C for 6 days after dry lamination, and which was not subjected to corona discharge treatment. did. Regarding transparency, we tested the single layer film immediately after molding and the 80°C film in an atmosphere of 40℃ without dry laminating.
The transparency of single layer films aged for 1 day was compared. A small change indicates that bleeding of fatty acid amide is small and transparency is not inhibited. Blocking properties were measured between the corona discharge treated surface and the non-corona discharge treated surface of the single layer film. As shown in Table 1, fatty acid amides with a solubility of 0.8 g or less have little change in slipperiness, transparency,
It can be seen that the blocking properties are also satisfactory.

[Table] Examples 6-7, Comparative Example 5 Propylene-ethylene-butene-1 as resin
Random copolymer (ethylene content 2.0% by weight,
Butene-1 content 12.5% by weight, melting peak temperature
The experiment was conducted in the same manner as in Example 1, except that the temperature was 131.0°C, MFR 5.5 g/10 minutes), and the type and amount of fatty acid amide shown in Table 2 were used. The heat sealability of the laminated films was also evaluated. Comparative Example 6 An experiment was carried out in the same manner as in Comparative Example 2, except that a propylene homopolymer (melting peak temperature 159.5°C, MFR 10.4 g/10 minutes) was used as the resin. In the case of a propylene homopolymer, even without using the fatty acid amide of the present invention, there is little deterioration in slipperiness after dry lamination. Comparative Example 7 Propylene-ethylene random copolymer (ethylene content 1.5% by weight, melting peak temperature
The experiment was conducted in the same manner as in Example 6, except that 153.2° C. and MFR of 9.2 g/10 minutes were used.

【table】

[Table] Examples 8 to 9, Comparative Example 8 The resin was a propylene-ethylene random copolymer (ethylene content 5.3% by weight, melting peak temperature
134.0℃, MFR7.0g/10min), except that 0.10 parts by weight of fatty acid amide shown in Table 3 was added.
An unstretched film was produced under the same conditions as in Example 1. Next, a biaxially oriented nylon film (15μ) and a biaxially oriented polyester film (12μ) were used as the base material layer for dry lamination, and dry lamination was performed and evaluated.

〔Effect of the invention〕

The present invention is particularly advantageous in that there is no significant decrease in slipperiness after high-temperature aging treatment of multilayer films, and
There are no limitations on aging temperature, such as:
It is a composition that can achieve practical adhesive strength between multiple layers in a short period of time, and has good transparency and heat sealability.

Claims (1)

[Claims] 1 0.01 to 0.5 parts by weight of a fatty acid amide having a solubility in 100 g of ethyl acetate of 0.8 g or less in 100 parts by weight of a propylene-α-olefin copolymer resin having a melting peak temperature of 145°C or less as determined by the DSC method. 1. A propylene copolymer laminate film, characterized in that an unstretched film made of the above composition is laminated with a base film via an adhesive layer. 2. The laminated film according to claim 1, wherein the propylene-α-olefin copolymer resin is a propylene-ethylene random copolymer resin or a propylene-ethylene-butene-1 random copolymer resin. 3. Claim 1, wherein the fatty acid amide is at least one amide selected from behenic acid, N-stearyl stearic acid, N-stearyl behenic acid, N-oleyl behenic acid, and N-stearyl erucic acid. The laminated film described.