JP3021139B2 - Laminated paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated paper excellent in slipperiness and moisture proofness used for packaging and the like.

[0002]

2. Description of the Related Art As a laminated paper used for packaging and the like, conventionally, a high-pressure polyethylene obtained by extrusion laminating a paper base material has been often used. This is because the laminate layer has a good balance of physical properties such as adhesive strength, water resistance, moisture resistance, heat sealability, and abrasion resistance, and is excellent in molding workability during extrusion lamination.

[0003]

However, extrusion-laminated high-pressure polyethylene on a paper substrate has poor sliding properties and requires improvement in moisture resistance. An object of the present invention is to provide a laminated paper having excellent adhesion between a paper base material and a resin layer, and excellent in slipperiness and moisture resistance.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems. As a result, the paper base material has (A) a melt flow rate of 1 to 50 g / 10 minutes and a density of 0.1 to 0.5 g. 8
20 to 80% by weight of a copolymer of ethylene and α-olefin of 80 to 0.940 g / cm ³ , a melt flow rate of 0.5 to 50 g / 10 min, and a density of 0.915 to
High pressure method polyethylene 80 of 0.935 g / cm ³
20% by weight of an ethylene polymer composition, and (B)
60 to 95% by weight of a propylene polymer having a melt flow rate of 2 to 100 g / 10 min, a melt flow rate of 0.5 to 50 g / 10 min, and a density of 0.915 to 0.9
A propylene polymer composition having a melt flow rate of 5 to 80 g / 10 minutes, comprising 40 to 5% by weight of a high-pressure polyethylene having a pressure of 35 g / cm ³ , so that the composition (A) is on the paper substrate side, and The ratio of the thickness of the layer made of the composition (A) to the thickness of the layer made of the composition (B) is 0.1 to 0.5.
It has been found that by performing coextrusion lamination molding so that the ratio is 0.9 to 0.5, a laminated paper that solves the problem can be obtained.

[0005] That is, laminated paper using a propylene-based polymer is considered to be one means for solving the problems of the present invention because of its excellent slipperiness and moisture-proofing properties. Has disadvantages. However,
By using the composition (A) and the composition (B) according to the present invention, the adhesiveness to a paper substrate is also improved while maintaining the advantages of a propylene-based polymer such as slipperiness and moisture resistance. It became possible to do.

The copolymer of ethylene and α-olefin according to the present invention includes ethylene and propylene, butene-1,
Hexene-1, octene-1,4-methyl-pentene-
A copolymer with 1 or the like or a mixture thereof, having a melt flow rate of 1 to 50 g / 10 min and a density of 0.880 to
0.940 g / cm ³ . This copolymer can be obtained by a production method called a medium-low pressure method using a Ziegler catalyst or the like.

[0007] The melt flow rate (hereinafter abbreviated as MFR) is measured according to condition 4 of JIS-K-7210. When the MFR is less than 1 g / 10 minutes, there is a disadvantage that the motor load at the time of extrusion lamination molding is increased and the production amount is reduced. Further, when the MFR exceeds 50 g / 10 minutes, neck-in of the molten film during extrusion lamination molding [In the extrusion lamination molding, a phenomenon in which the width of the molten film coming out of the T die becomes narrower in the space until it comes into contact with the base material. , (Difference between the width of the molten film at the exit of the T-die and the width of the laminated film laminated on the substrate)]. Preferably 3.5 to 20
g / 10 minutes.

If the density is less than 0.880 g / cm ^3, it is difficult to manufacture. On the other hand, when the density exceeds 0.940 g / cm ³ , there is a disadvantage that the motor load during extrusion lamination molding is increased, the production amount is reduced, and the adhesion to the paper base material is reduced. Preferably 0.910 to 0.935
g / cm ³ .

[0009] The high-pressure polyethylene which forms an ethylene polymer composition together with the above-mentioned copolymer of ethylene and an α-olefin is obtained by polymerizing ethylene under a high pressure of 1000 to 3000 kg / cm ³ . The high pressure polyethylene according to the present invention has an MFR of 0.5 to 50 g / 10 min and a density of 0.915 to 0.935 g / cm ³ .

If the MFR is less than 0.5 g / 10 minutes, there is a drawback that the load on the motor during extrusion lamination molding becomes large and the production amount is reduced. In addition, the MFR is 50 g / 10
If the amount exceeds the above range, there is a disadvantage that the neck-in of the molten film is large at the time of extrusion lamination, and the extrusion lamination is difficult. Preferably it is 1 to 20 g / 10 minutes.

If the density is less than 0.915 g / cm ^3, it is difficult to manufacture. Further, even if the density exceeds 0.935 g / cm ³ , production becomes difficult.

The ethylene polymer composition according to the present invention comprises:
The above copolymer of ethylene and α-olefin 20 to 80
% By weight and 80 to 20% by weight of the high-pressure polyethylene. If the copolymer of ethylene and α-olefin is less than 20% by weight, the adhesion to the propylene-based polymer composition is poor. There is a disadvantage that lamination molding is difficult. Preferably 20-6
0% by weight.

Next, the propylene polymer composition (B) according to the present invention will be described. The propylene polymer which is a component of the propylene-based polymer composition (B) is obtained by polymerizing propylene using a so-called Ziegler-Natta catalyst, and may contain a small amount of ethylene. MFR (JIS-
(Measured under the condition 14 of K-7210) is 2 to 10
0 g / 10 minutes. If the MFR is less than 2 g / 10 minutes,
The drawback that the draw-down property during extrusion lamination molding (meaning the extensibility of the molten film or the thin-film formability in extrusion lamination, which is indicated by (maximum take-off speed at which the molten film does not break at a constant extrusion rate)) is poor. There is. on the other hand,
When the MFR exceeds 100 g / 10 minutes, there is a disadvantage that the neck-in of the molten film is large at the time of extrusion lamination molding and the extrusion lamination is difficult. Preferably 10 to 50 g
/ 10 minutes.

The high-pressure polyethylene, which is another component of the propylene polymer composition (B), is MFR (provided that JIS-K
(Measured according to condition 4 of -7210) is 0.5 to 50
g / 10 min, density 0.915 to 0.935 g / cm ³
It is.

[0015] If the MFR is less than 0.5 g / 10 minutes, there is a disadvantage that the load on the motor during extrusion lamination molding becomes large and the production amount decreases. In addition, the MFR is 50 g / 10
If the amount exceeds the above range, there is a disadvantage that the neck-in of the molten film is large at the time of extrusion lamination, and the extrusion lamination is difficult. Preferably it is 1 to 20 g / 10 minutes.

If the density is less than 0.915 g / cm ^3, it is difficult to manufacture. Further, even if the density exceeds 0.935 g / cm ³ , production becomes difficult.

The propylene polymer composition (B) comprises 60 to 95% by weight of a propylene polymer and high pressure polyethylene 4
0 to 5% by weight, MFR (however, JIS-K-7
210 as measured under condition 14) of 5 to 80 g / 1
It must be 0 minutes.

If the propylene polymer is less than 60% by weight,
Laminated paper has the disadvantage of poor slipperiness and moisture resistance. On the other hand, if it exceeds 95% by weight, the neck-in of the molten film becomes large at the time of extrusion lamination molding, and a surging phenomenon (pulsation phenomenon of the molten film thickness) appears, which makes it difficult to perform stable extrusion lamination molding.

On the other hand, if the MFR is less than 5 g / 10 minutes, the drawdown property at the time of extrusion laminating becomes poor, and the MF
If R exceeds 80 g / 10 minutes, there is a drawback that the neck-in of the molten film is large during extrusion lamination molding, making extrusion lamination difficult. Preferably 10 to 40 g / 10
Minutes.

In the present invention, the ethylene polymer composition (A) is disposed on the paper substrate side, the propylene polymer composition (B) is disposed on the outside, and the thickness of the layer comprising the composition (A) B) The ratio of the thickness of the layer made of the composition is from 0.1 to 0.1.
It is necessary to co-extrude the laminate so that the ratio is 5 to 0.9 to 0.5. If the thickness ratio of the layer comprising the composition (A) is less than 0.1, the adhesiveness of the laminate film to the paper substrate will be poor. On the other hand, when the ratio exceeds 0.5, the moisture-proof property of the laminated paper decreases.

The co-extrusion laminate molding according to the present invention comprises:
In a method using a general co-extruder and a laminator, for example, on at least one surface of a substrate supplied at 50 to 350 m / min, using a two-layer, two-layer co-extruder, the ethylene-based polymer composition and propylene Melt co-extrusion so that the layer composed of the ethylene-based polymer composition is bonded to the substrate, and pressure-bonded between a cooling roll and a pressing roll,
After cooling and solidifying the molten film along the cooling roll surface,
Examples of the method include winding into a roll.

When the above-mentioned two-type two-layer co-extruder is used as the co-extrusion apparatus, the joining method of the layer composed of the ethylene-based polymer composition and the layer composed of the propylene-based polymer composition is as follows. Either the inner or outer die can be used, but the die pre-joining method is particularly preferable from the viewpoint of coextrusion laminating moldability and the cost of the apparatus.

The temperature of the two-layer, two-layer co-extruded molten film is 230 to 330 ° C. immediately below the die, especially 250 to 3 ° C.
20 ° C. is preferred. When the temperature of the two-type two-layer co-extruded molten film is 23
If the temperature is less than 0 ° C., the draw-down property of the molten film is poor, so that extrusion lamination is difficult to perform, and the adhesion of the laminated film to the paper substrate is poor. Further, when the temperature of the two-type two-layer co-extruded molten film exceeds 330 ° C., there is a disadvantage that the neck-in of the molten film is large and extrusion lamination is difficult.

In the present invention, the temperature of each of the two types of two-layer co-extruded molten films of the ethylene polymer composition layer and the propylene polymer composition layer need not be the same. The temperature difference may be positively set. For example, in order to enhance the adhesion between the layer composed of the ethylene-based polymer composition and the substrate, the layer composed of the ethylene-based polymer composition is higher than the layer composed of the propylene-based polymer composition. A method of increasing the neck-in of the layer co-extruded molten film such that the layer made of the propylene-based polymer composition is lower than the layer made of the ethylene-based polymer composition may be used as necessary.

Further, in the present invention, the two-layer two-layer co-extruded molten film extruded from the die is bonded to the base material until it is bonded.
Ozone gas or the like may be sprayed on the surface of the two-layer, two-layer co-extruded molten film made of the ethylene-based polymer composition between the so-called air gaps to increase the adhesion to the substrate. Alternatively, in order to enhance the adhesion to the substrate, a tackifier such as a terpene resin, an ionomer, or ethylene-acrylic acid may be added to the layer of the two-layer, two-layer co-extruded molten film composed of the ethylene-based polymer composition. An adhesive resin such as an ester copolymer or an acid-modified polyethylene may be added.
Further, in order to enhance the adhesiveness with the layer made of the ethylene-based polymer composition, the base material may be subjected to a pretreatment such as an anchor coat treatment, a corona discharge treatment, and a flame treatment.

The cooling roll used in the present invention may have any surface finish, such as a mat, a semi-mat, and a mirror, but a mat finish roll is particularly preferable from the viewpoint of ensuring slipperiness.

[0027]

The present invention will be described below with reference to examples. The evaluation of the physical properties in the examples was based on the following methods. A) Neck-in The neck-in of the co-extruded laminate film was measured. 〇 has a neck-in of 65 mm or less, and there is little unevenness in thickness near both ends. Δ indicates that the neck-in was 85 mm or less and the thickness was uneven near both ends. × is 85 for neck-in
mm, and the thickness unevenness near both ends is remarkable. In the case of Δ and ×, not only the product width of the laminated paper becomes too narrow, but also the winding tension becomes non-uniform in the width direction, and there is a risk that slack or breakage occurs. It is also possible to trim (cut off) a portion having an uneven thickness, but this is not preferable because loss is large and uneconomical. It must be the result of 〇.

B) Adhesiveness The laminated paper was torn by hand, and the laminated film was peeled off. The behavior of the laminated film was observed and the sensory evaluation was performed.は indicates a state in which the lamination film in the tearing portion has little stringiness or no interfacial peeling, is difficult to peel off, and is accompanied by destruction of the paper substrate. △ indicates a state in which the lamination film in the tearing portion has a large amount of stringing or elongation or peeling at the interface, and if the film is carefully peeled, it can be partially peeled without destruction of the paper substrate. X indicates a state in which the laminate film at the tearing portion is well stretched or interfacial peeling occurs, and the paper substrate can be peeled off relatively easily without destruction. Δ and × are not preferred because there is a risk of peeling of the laminated film during use of the laminated paper as a packaging material. It must be the result of 〇.

C) Sliding property The coefficient of friction between the laminated film surface of the laminated paper and the high-quality paper (basis weight 52.3 g / m ² ) was measured in accordance with ASTM-D-1894. Vertical load 625g, tensile speed 50
mm / min, measured in a measurement environment of 23 ° C.-65% RH. If the coefficient of kinetic friction exceeds 0.4, the use of laminated paper as a packaging material will make it difficult to take out the packaged object,
Alternatively, the slipperiness of the surface of the packaged object is deteriorated. It is necessary that the dynamic friction coefficient is 0.4 or less.

D) Moisture Proof Based on JIS-Z-0280, the moisture permeability of the laminated paper was measured using a digital water vapor permeability tester (humidity sensor type) manufactured by Lissi. The measurement was performed at 40 ° C. and 90% RH with the laminate film surface on the humidified side. However, the laminate film thickness is 20 μm. In moisture permeability 16g / m ² · ²
If it exceeds 4 hrs.atm, when the laminated paper is used as a packaging material, it absorbs a large amount of moisture to the packaged object, and the protection of the packaged object is poor, which is not preferable. In moisture permeability 16g / m ² · 24
hrs · atm or less.

Example 1 40% by weight of an ethylene-hexene 1 copolymer having a MFR of 8 g / 10 min and a density of 0.930 g / cm ³ and an MFR of 12 g /
After mixing with 60% by weight of high pressure polyethylene having a density of 0.917 g / cm ³ for 10 minutes with a tumbler mixer,
The mixture was melt-mixed using a 0 mm extruder, MFR 9 g / 10 min,
An ethylene resin composition having a density of 0.922 g / cm ³ was obtained.

On the other hand, MFR 18 g / 10 min, density 0.9
80 g / cm ³ of propylene polymer 80% by weight and MFR
1 g / 10 min, 20 wt% of high pressure polyethylene having a density of 0.920 g / cm ³ were mixed with a tumbler mixer.
Melt and mix using a 40 mm diameter extruder, MFR 15 g /
A propylene-based resin composition having a density of 0.905 g / cm ³ for 10 minutes was obtained.

The above-mentioned ethylene resin composition has 6
high-quality paper (weight: 30 m / m ² or more) which was co-extruded so that the propylene-based resin composition became 14 μm on the surface of the laminated paper, and was subjected to a corona discharge treatment supplied at a speed of 100 m / min. 52.3 g / m ² ) to obtain a co-extruded laminated paper consisting of [quality paper / ethylene-based resin composition / propylene-based resin composition]. The co-extrusion laminator has a diameter of 90 mm (L / D = 2
9) and a die pre-joining co-extruder equipped with two extruders having a diameter of 65 mm (L / D = 28). The T-die has a straight manifold, a lip gap of 0.8 mm and an inner deckle. To adjust the width to 750 mm. The cooling roll had a matte finish, and the pressing roll used neoprene rubber. In the corona discharge treatment, a high voltage was applied between the gap between the aluminum electrode and the insulating roll to generate a corona discharge, in which a paper substrate passed along the insulating roll. Here, the processing amount (w minute / m ² ) = output (w) ÷ electrode width (m) ÷ through acceleration (m / min). Table 1 shows the evaluation results of the obtained co-extruded laminated paper.
It was shown to. Neck-in, adhesion, slippage, and moisture-proof properties were all satisfactory.

Example 2 10 μm of the ethylene resin composition of Example 1 was applied to the paper substrate side.
m, except that the propylene-based resin composition was co-extruded on the surface of the laminated paper so as to have a thickness of 10 μm. Table 1 shows the evaluation results of the obtained co-extruded laminated paper.
It was shown to. Neck-in, adhesion, slippage, and moisture-proof properties were all satisfactory.

Example 3 The ethylene resin composition of Example 1 was 2 μm thick on the paper substrate side.
The propylene resin composition has 18
The same operation was carried out except that co-extrusion was performed so as to have a thickness of μm.
Table 1 shows the evaluation results of the obtained co-extruded laminated paper. Neck-in, adhesion, slippage, and moisture-proof properties were all satisfactory.

Comparative Example 1 The co-extrusion of Example 1 was repeated using only the propylene resin composition.
The same procedure was carried out except for extruding a single layer of 0 μm. Table 1 shows the evaluation results of the single-layer extruded laminated paper comprising the obtained [high quality paper / propylene resin composition]. Although slipperiness and moisture resistance were good, the results were unsuitable as wrapping paper due to poor adhesion to paper.

COMPARATIVE EXAMPLE 2 The coextrusion of Example 1 was carried out using only the ethylene resin composition for 20 times.
The same operation was carried out except for extruding a single layer of μm. Table 1 shows the evaluation results of the obtained single-layer extrusion-laminated paper made of the high-quality paper / ethylene-based resin composition. Although the adhesion to paper was good, the results were poor for slippage and moisture-proof properties and unsuitable as packaging paper.

Comparative Example 3 The ethylene-based resin composition of Example 1 was used in an MFR of 8 g / 10
Minute, ethylene-hexene having a density of 0.930 g / cm ³
40% by weight of 1 copolymer, 60% by weight of high-pressure polyethylene having a MFR of 12 g / 10 min and a density of 0.917 g / cm ³
Was mixed with a tumbler mixer, and then melt-mixed using an extruder having a diameter of 40 mm to obtain an MFR of 9 g / 10 min and a density of 0.92.
An ethylene resin composition of 2 g / cm ³ was obtained.

[0039]

[Table 1]

[0040]

According to the present invention, a laminated paper having a small neck-in during the co-extrusion lamination molding, having excellent adhesion between the paper base material and the resin layer, and having excellent slipperiness and moisture-proof properties was obtained.

Continuation of the front page (72) Inventor Katsuji Ohira 3-2 Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Showa Denko KK Kawasaki Resin Laboratory (56) References JP-A-60-35728 (JP, A) JP-A-61-197239 (JP, A) JP-A-51-105411 (JP, A) JP-A-4-269530 (JP, A) JP-A-58-33459 (JP, A) JP-A-57-88545 (JP, A) , U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 B65D 65/40 D21H 1/00-27/42

Claims (1)

(57) [Claims] 1. A paper base having (A) a melt flow rate of 1 to 50 g / 10 min and a density of 0.880 to 0.940 g
/ Cm ³ of 20 to 80% by weight of a copolymer of ethylene and α-olefin and a melt flow rate of 0.5 to 50
g / 10 min, density 0.915 to 0.935 g / cm ³
(B) a propylene polymer having a melt flow rate of 2 to 100 g / 10 min.
5% by weight and melt flow rate of 0.5 to 50 g / 10
A propylene polymer composition having a melt flow rate of 5 to 80 g / 10 min, comprising 40 to 5% by weight of a high-pressure polyethylene having a density of 0.915 to 0.935 g / cm ³ and a composition of (A). Is on the paper substrate side, and the ratio of the thickness of the layer made of the composition (A) to the thickness of the layer made of the composition (B) is 0.1 to 0.5 to 0.9 to 0.5. 5. A laminated paper obtained by coextrusion laminating as described in 5.