JP5496811B2 - Laminates for paper packaging materials - Google Patents

Description

  The present invention relates to a laminate for paper wrapping material having excellent slip performance even when stored at a high temperature after lamination in a field where a film as a sealant material is used for a base material layer mainly composed of paper. is there.

  Conventionally, polyethylene has been used as a sealant film for paper packaging materials, and various lubricants such as higher hydrocarbons, higher fatty acids, ester derivatives, amide derivatives, organic or inorganic fine particles have been used to impart slip properties. Yes. This technology has made it possible to impart excellent slip properties to the sealant film. However, in the season when the temperature becomes high, the slip property over time cannot be maintained due to the high temperature, and there is a problem that it decreases.

  For example, a specific polyethylene film is used as a sealant layer for a base layer of a biaxially stretched nylon film (Patent Document 1). According to this document, an amide compound is used as a lubricant (slip agent) together with fine particles of an inorganic filler and an organic filler as an antiblocking agent in the sealant layer, but there is no mention of a base material layer mainly composed of paper. Moreover, the problem that the adhesiveness of a sealant layer changes with time is not pointed out.

  Next, for gas barrier films such as nylon and polyester, polyethylene is used as the sealant layer, and specific amounts of glycerin fatty acid ester, propylene glycol fatty acid ester and fatty acid bisamide are blended in the polyethylene, and excellent slip performance is achieved. It is supposed to be obtained (Patent Document 2). However, there is no reference to the base material layer mainly composed of paper, and the composition of the slip agent is also complicated. There is no point out that the adhesiveness of the sealant layer changes with time.

  In addition, blending unsaturated fatty acid amide, unsaturated fatty acid bisamide, and specific polymer fine particles in layer A of a two-layer polyethylene laminated film consisting of layer A and layer B with specified monomer composition and physical properties, provides slip resistance and blocking resistance. A film with improved mechanical suitability such as is known (Patent Document 3). This document describes that the B layer side is surface-treated and laminated on the base material layer, but it is described that the paper base material layer is laminated on the A layer with improved mechanical properties such as slip properties. Absent.

  As a laminate of a paper substrate and an ethylene-based resin, a predetermined amount of unsaturated fatty acid bisamide and unsaturated fatty acid amide are blended with an ethylene / α-olefin copolymer having a specific molecular weight distribution and composition distribution in the sealant layer. Films with improved mechanical suitability such as low-temperature heat sealability, anti-blocking properties and slipperiness are known (Patent Document 4, [Claim 5], amended in the procedure amendment dated September 6, 1996) [0061]). This document mentions that a paper material may be used as a base material for the laminate, but does not describe the problem that the slipperiness and adhesiveness of the sealant layer change with time.

JP 2004-250464 A JP 2001-200109 A JP-A-8-252894 Japanese Patent Laid-Open No. 9-59442

  An object of the present invention is to solve the above-mentioned conventional problems and to provide a laminate for paper packaging material having excellent slip properties even when stored at high temperatures.

  As a result of intensive studies to achieve the above object, the present inventors have obtained a laminate excellent in slipping property and adhesiveness even under high-temperature storage conditions by using a fatty acid amide and a fatty acid bisamide in combination. The inventors have found that the performance can be maintained and have reached the present invention.

That is, the gist of the present invention is that a base material layer mainly composed of paper having a basis weight of 5 to 50 g / m ² , a melt flow rate of 1 to 50 g / 10 minutes, and a density of 0.880 to 0. A sealant layer mainly composed of an ethylene-based resin at 940 g / cm ³ , and the sealant layer comprises 0.1 to 0.35 parts by weight of a fatty acid amide and 0.1 parts of a fatty acid bisamide with respect to 100 parts by weight of the ethylene-based resin. It exists in the laminated body for paper packaging materials characterized by mix | blending -0.35 weight part.

Furthermore, another gist of the present invention is that the ethylene-based resin is a high pressure radical polymerization polyethylene having a melt flow rate of 1 to 50 g / 10 min and a density of 0.900 to 0.930 g / cm ^3. It exists in the said laminated body for paper packaging materials characterized.

  Another gist of the present invention resides in the laminate for paper packaging material, wherein the fatty acid amide and the fatty acid bisamide have an unsaturated group.

  Furthermore, the other summary of this invention exists in the said laminated body for paper packaging materials characterized by carbon number of fatty acid amide and fatty acid bisamide being 16-30.

  Furthermore, another gist of the present invention resides in the laminate for a paper packaging material, wherein the blending ratio of the fatty acid amide and the fatty acid bisamide is in the range of 30/70 to 60/40 (weight ratio). .

  Furthermore, another gist of the present invention resides in the laminate for paper packaging material, wherein the laminate is formed by an extrusion lamination method.

  According to the present invention, even when stored at a high temperature, a laminate of an ethylene-based resin composition and paper having excellent slip properties and hand cutting properties can be provided. The laminate is useful as a laminate for paper packaging materials.

  The laminate for paper packaging material of the present invention comprises a base material layer mainly composed of paper and a sealant layer mainly composed of an ethylene-based resin. This sealant layer is sometimes called a heat seal layer.

  The ethylene-based resin used in the present invention has a melt flow rate (MFR) of 1 to 50 g / 10 minutes measured at 190 ° C. and a load of 2.16 kg in accordance with JIS K6922-2 (2005). When the MFR is less than 1 g / 10 min, the melt viscosity is high, so the moldability is inferior. When the MFR exceeds 50 g / 10 min, the melt viscosity is low, so the neck-in increases and the melt film stability is inferior. Preferably, the MFR is 5 to 20 g / 10 min.

The ethylene resin used in the present invention has a density measured according to JIS K7112 (1999) of 0.880 to 0.940 g / cm ³ , preferably 0.890 to 0.935 g / cm ³ , and particularly preferably. Is in the range of 0.900 to 0.930 g / cm ³ . When the density increases, the low temperature heat sealability deteriorates.

  The ethylene-based resin used in the present invention is polyethylene having the above MFR and density, and is a copolymer containing ethylene in addition to a homopolymer of ethylene. From the top of the manufacturing method, it is classified into the following two types. That is,

(1) High-pressure radical polymerization polyethylene or polyethylene copolymer obtained by using ethylene or a small amount of monomer capable of radical copolymerization with ethylene using a radical generator such as organic peroxide or oxygen Further, these are polyethylenes modified with maleic anhydride or α, β-unsaturated carboxylic acid by a known method, preferably high pressure radical polymerization polyethylene, ethylene homopolymer, ethylene-vinyl acetate copolymer. It is a coalescence.
(2) An ethylene / α-olefin copolymer obtained by copolymerizing ethylene and α-olefin in the presence of a catalyst such as a Ziegler catalyst, chromium oxide catalyst, molybdenum oxide catalyst, metallocene catalyst, etc. Examples thereof include polyethylene obtained using a catalyst.

The α-olefin used above is represented by the general formula R—CH═CH ₂ (wherein R represents an alkyl group having 1 or more carbon atoms). Specific examples thereof include propylene, 1- Examples include butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 4-methyl-1-hexene, 4,4-dimethyl-1-pentene, and octadecene. Among these α-olefins, the resulting laminate is excellent in tensile strength, tear strength, impact strength, heat seal strength, etc., so 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 4-methyl-1-hexene, and 4,4-dimethyl-1-pentene are preferred. The ethylene / α-olefin copolymer is obtained by copolymerizing at least one of these α-olefins with ethylene, specifically, ethylene / butene-1, ethylene / 1-hexene copolymer. , Ethylene / 1-heptene copolymer, ethylene / 1-octene copolymer, ethylene / 4-methyl-1-pentene copolymer, ethylene / propylene / 1-hexene terpolymer.

  For the polymerization catalyst, a Ziegler type catalyst (ie, based on a combination of a supported or unsupported halogen-containing titanium compound and an organoaluminum compound), a metallocene catalyst (ie, a combination of a supported or unsupported metallocene compound and an organoaluminum compound, particularly an alumoxane) Based on the Kaminsky catalyst).

  Other catalysts include a chromium catalyst component (Phillips catalyst) that is supported on an inorganic oxide carrier such as alumina, silica / alumina, and is fired in a non-reducing atmosphere so that at least a part of the chromium atoms are hexavalent. Is mentioned.

  An important feature of the present invention resides in that a predetermined amount of fatty acid amide and fatty acid bisamide are blended with the above-mentioned ethylene resin to form an ethylene resin composition, which is used as a sealant layer. Here, the fatty acid amide is a monoamide of a fatty acid and contains one equivalent of an amide group in one molecule, and the fatty acid bisamide contains two equivalents of an amide group in one molecule. The fatty acid may be a saturated fatty acid having no unsaturated group in the molecule or an unsaturated fatty acid having an unsaturated group, but it is possible to improve the lubricity of the sealant layer without impairing the adhesion to the laminated substrate. Therefore, unsaturated fatty acids are preferred.

Specifically, saturated fatty acid amides such as palmitic acid amide, stearic acid amide, behenic acid amide (behenic acid amide);
Unsaturated fatty acid amides such as oleic acid amide and erucic acid amide:
Methylene bis stearic acid amide, ethylene bis stearic acid amide, ethylene bis behenic acid amide, ethylene bis capric acid amide, ethylene bis lauric acid amide, ethylene bis hydroxy stearic acid amide, hexamethylene bis stearic acid amide, hexamethylene bis hydroxy acid Saturated fatty acid bisamides such as stearic acid amide, N, N′-bisstearyl adipic acid amide, N, N′-bisstearyl sebacic acid amide:
Unsaturation such as methylene bis oleic acid amide, ethylene bis oleic acid amide, ethylene bis erucic acid amide, hexamethylene bis oleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide Fatty acid bisamide is mentioned.
Here, the number of carbon atoms of the fatty acid is preferably 16 to 30, particularly 18 to 26.

  The blending amount of the fatty acid amide with respect to 100 parts by weight of the ethylene-based resin is selected from the range of 0.1 to 0.35 parts by weight, and the blending amount of the fatty acid bisamide is selected from the range of 0.1 to 0.35 parts by weight. When the amount is less than 0.1 part by weight, the slip property of the film after lamination, which is the object of the present invention, cannot be obtained. When the amount exceeds 0.35 part by weight, the adhesive strength between the film after lamination and the substrate is low. not enough.

  The blending ratio (weight ratio) of the fatty acid amide and the fatty acid bisamide of the present invention is preferably 30/70 to 60/40. Especially preferably, it is the range of 40 / 60-50 / 50. Fatty acid amides are excellent in slip properties, but when stored at high temperatures, they are adsorbed on the paper base material, slip properties decrease, and hand cutting properties decrease when the blending amount increases. Fatty acid bisamide is inferior in slipping property and hand cutting property to fatty acid amide, but when stored at a high temperature, it is difficult to be adsorbed on a paper base material and the slipping property is difficult to be lowered.

  The ethylene-based resin composition of the present invention contains an ethylene-based resin having a specific MFR and density, fatty acid amide, and fatty acid bisamide as essential components. Various additives such as absorbents, antiblocking agents, droplets, weathering agents, pigments, dyes, fillers, slip agents other than the claims, antistatic agents, etc. are blended within a range that does not impair the purpose of the present invention. May be.

  In order to obtain the ethylene-based resin composition of the present invention, the necessary components are mixed by, for example, a tumbler blender or a Henschel mixer, and after mixing, the components are further melt-kneaded by a single screw extruder, twin screw extruder, or the like. A granulation method or a melt kneading granulation method using a Banbury mixer or the like is used. Further, a method is adopted in which each of the fatty acid amide and the fatty acid bisamide of the present invention or a mixture thereof is mixed in advance with a certain amount of resin to create a master batch, and then mixed with the remaining resin and melt-kneaded for production. Also good.

On the other hand, examples of the base material layer mainly composed of paper constituting the laminate of the present invention include thin paper, fine paper, glassine paper and the like, and the basis weight is 5 to 50 g / m ² , preferably 10 to 30 g / m ² is used. When the basis weight is less than the lower limit, the strength is lowered, and when the basis weight is exceeded, the slip property is lowered. The base material layer is preferably subjected to surface treatment such as corona discharge treatment, ozone treatment, and low-temperature plasma treatment.

  As a method for producing a laminate by laminating the ethylene resin composition of the present invention as a sealant layer on a base material layer mainly composed of paper, a single laminate method, a tandem laminate method, a sandwich laminate method, a co-pressing laminate method, etc. Known methods such as an extrusion laminating method and a dry laminating method can be used. Similarly, the thickness of the sealant layer depends on the use of the packaging material, but is usually 5 to 30 μm, preferably 10 to 20 μm.

  EXAMPLES Next, the present invention will be specifically described by way of examples. However, the present invention is not limited by these unless it exceeds the gist. In addition, measurement of performance in Examples and Comparative Examples, and materials used (polyethylene, amide compound, paper) are shown below. Moreover, the part in an Example and a comparative example is a weight part.

[Measurement of performance]
(1) Melt flow rate (MFR):
Based on JIS K6922-2 (2005), it measured by 190 degreeC and the load 2.16kg.
(2) Density:
In accordance with JIS K7112 (1999), the density was measured using a density gradient tube kept at 23 ° C.
(3) Slip property:
The laminated film surfaces after lamination were attached to the slant test machine (made by HEIDON) thread (200 g) and a tilt plate, and then the tilt plate was tilted at a tilt angular velocity of 1.7 ° / sec. When the sled began to slide, the angle (θ) was read and the static friction coefficient (μS) was measured.
μS = tan θ (θ: angle at the start of sliding)
The slip property was measured after 7 days and 30 days after storing the laminate in an atmosphere at 45 ° C. The slip property value is acceptable if it is 0.30 or less, and preferably 0.20 or less.
(4) Hand cutting ability:
As a result of tearing the laminate by hand, the resin in the sealant layer is cut along with the paper, and the resin with good hand cutability and no resin elongation occurs. The result was indicated by Δ, and the adhesiveness between the paper and the resin was poor, only the paper was cut, and the resin was not cut by hand due to resin elongation.

[Materials used]
(1) High-pressure method low-density polyethylene Polyethylene homopolymer produced by high-pressure radical polymerization at a density of 0.919 g / cm ³ and MFR of 7.0 g / 10 min (manufactured by Nippon Polyethylene Co., Ltd., trade name Novatec LD LC600A)
(2) An ethylene / α-olefin copolymer (manufactured by Nippon Polyethylene Co., Ltd.) having a density of 0.913 g / cm ³ , MFR 8.0 g / 10 min and a comonomer of 1-hexene produced by an ethylene copolymer metallocene catalyst. Product name Harmolex NH745N)
(3) Unsaturated fatty acid amide erucic acid amide (Nippon Yushi Co., Ltd., Alflow P10)
(4) Unsaturated fatty acid bisamide ethylenebisoleic acid amide (Nippon Yushi Co., Ltd., Alflow AD281)
(5) Base layer paper thin paper (basis weight 23 g / m ² ) or fine paper (basis weight 70 g / m ² )

[Example 1]
Each component of the high pressure method low density polyethylene (1), erucic acid amide (3), and ethylenebisoleic acid amide (4) is mixed using a Henschel mixer with the compounding composition shown in Table 1, and is mixed with a 35 mmφ twin screw extruder. By melt-kneading, an ethylene resin composition was obtained.
The obtained resin composition was subjected to corona treatment on a paper substrate using a 90 mmφ laminator molding machine manufactured by Modern Machinery Co., Ltd., and then extruded under the conditions of a die width: 560 mm, a molding temperature: 320 ° C., and a processing speed of 180 m / min. Lamination was performed to obtain a laminate having a base material layer mainly composed of paper having a resin thickness (the thickness of the sealant layer) of 15 μm.
Table 1 shows the measurement results of the slip property and hand cutting property of the obtained extruded laminate.

[Example 2], [Comparative Example 1] to [Comparative Example 3]
A base material mainly composed of paper in the same manner as in Example 1 except that each component of erucic acid amide (3) and ethylenebisoleic acid amide (4) was changed to the composition shown in Table 1 in Example 1. A laminate having a layer was obtained.
Table 1 shows the measurement results of the slip property and hand cutting property of the obtained extruded laminate.

[Comparative Example 4]
In Example 2, a laminate was obtained in the same manner as in Example 2 except that the type of paper was changed.
Table 1 shows the measurement results of the slip property and hand cutting property of the obtained extruded laminate.

[Example 3]
Each component of ethylene-based copolymer (2), erucic acid amide (3), and ethylenebisoleic acid amide (4) produced by a metallocene catalyst is mixed using a Henschel mixer with the composition shown in Table 2. The mixture was melt-kneaded with a 35 mmφ twin-screw extruder to obtain an ethylene-based resin composition.
The obtained resin composition was subjected to corona treatment on a paper substrate using a 90 mmφ laminator molding machine manufactured by Modern Machinery Co., Ltd., and then extruded under the conditions of a die width: 560 mm, a molding temperature: 320 ° C., and a processing speed of 180 m / min. Lamination was performed to obtain a laminate having a base material layer mainly composed of paper having a resin thickness (the thickness of the sealant layer) of 15 μm.
Table 2 shows the measurement results of the slip property and hand cutting property of the obtained extruded laminate.

[Example 4], [Comparative Example 5] to [Comparative Example 7]
A base material mainly composed of paper in the same manner as in Example 2, except that the components of erucic acid amide (3) and ethylenebisoleic acid amide (4) were changed to the formulation shown in Table 2 in Example 3. A laminate having a layer was obtained.
Table 2 shows the measurement results of the slip property and hand cutting property of the obtained extruded laminate.

[Comparative Example 8]
In Example 4, a laminate was obtained in the same manner as in Example 4 except that the paper type was changed.
Table 2 shows the measurement results of the slip property and hand cutting property of the obtained extruded laminate.

  As is clear from Examples 1 to 4, a laminate composed of a base material mainly composed of paper of the present invention and a sealant layer in which a predetermined amount of fatty acid amide and fatty acid bisamide was blended in an ethylene-based resin was stored at a high temperature. Even in this case, it can be seen that the laminate has an excellent balance of slip and hand cutting properties.

  On the other hand, when the blending amount of fatty acid amide is 0.22 parts by weight (double blending amount with respect to Examples 1 to 4, but without blending of fatty acid bisamide) with respect to 100 parts by weight of the ethylene-based resin, It is inferior to slip property and hand cutting property (Comparative Examples 1 and 5).

  When the blending amount of only fatty acid amide is increased to 0.4 parts by weight without blending fatty acid bisamide, the slip property and hand cutting property are inferior (Comparative Examples 3 and 7).

  Moreover, when the blending amount of fatty acid bisamide is 0.22 parts by weight (double blending amount with respect to Examples 1 to 4, but without blending of fatty acid amide), the slip property is excellent, but it is easy to cut. Inferior (Comparative Examples 2 and 6).

When a slip agent is blended in the same manner as in Examples 2 and 4 and the basis weight of the paper wrapping material is increased to 70 g / m ² , the hand cutting property is improved, but the slip property is inferior (Comparative Examples 4 and 8).

Claims (6)

A base material layer mainly composed of paper having a basis weight of 5 to 50 g / m ² , an ethylene resin having a melt flow rate of 1 to 50 g / 10 minutes and a density of 0.880 to 0.940 g / cm ^3. The sealant layer is composed mainly of 0.1 to 0.35 parts by weight of fatty acid amide and 0.1 to 0.35 parts by weight of fatty acid bisamide with respect to 100 parts by weight of the ethylene-based resin. A laminate for paper packaging material, characterized in that The ethylene-based resin is polyethylene obtained by a high-pressure radical polymerization method having a melt flow rate of 1 to 50 g / 10 min and a density of 0.900 to 0.930 g / cm ^3. 2. Laminate for paper packaging material according to 1.   The laminate for paper packaging material according to claim 1 or 2, wherein the fatty acid amide and the fatty acid bisamide have an unsaturated group.   The laminated body for paper packaging materials according to any one of claims 1 to 3, wherein the fatty acid amide and the fatty acid bisamide have 16 to 30 carbon atoms.   The laminate for a paper packaging material according to any one of claims 1 to 4, wherein a blending ratio of the fatty acid amide and the fatty acid bisamide is in a range of 30/70 to 60/40 (weight ratio).   The laminate for a paper packaging material according to any one of claims 1 to 5, wherein the laminate is formed by an extrusion lamination method.