JP2014023443A - Laminate paper for biodegradable binding tape and binding tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide laminate paper for a binding tape having excellent mechanical strength and suitable weather resistance and capable of performing biodegradation in soil.SOLUTION: The laminate paper for a binding tape is obtained by laminating lactic acid aliphatic polyester containing 0.7 to 10 wt.% of a lactic acid component on both surfaces of a waterproof paper material with a thickness of 12 to 35 μm. A binging tape is composed of the laminate paper.

Description

  The present invention relates to a laminate paper and a binding tape for a binding tape having biodegradability, and in particular, even when used for attracting plants that take a long time until harvesting, the necessary strength is maintained until just before harvesting. The present invention relates to a laminated paper and a binding tape that provide a binding tape that can be used.

In plantation cultivation of vegetables, fruit trees, flowers, etc. in alleys and greenhouses etc., to support and attract these plants with pillars, nets, strings, etc., support plant stems, branches, vines, etc. Bundling work is being carried out. For such support and attraction, a string called an attracting string has been used in the past, but in recent years a ribbon-like binding tape (generally made of a synthetic resin film such as polyethylene and coated with an adhesive on one side) (Also called attracting tape), which can be used to bind the support and the plant semi-automatically using a tape binding machine.
However, when a synthetic resin film such as polyethylene is used as the binding tape, the binding tape must be cut with scissors to remove the plant from the support during or after harvesting. Since it becomes necessary to collect and clean up, there is a problem that these troubles are complicated.

  In order to solve such a problem, a binding tape made of a photo-disintegrating synthetic resin is used. According to this, although high intensity | strength is hold | maintained for a fixed period (about 2-3 months), after that, it will deteriorate with sunlight and intensity | strength will become low, and it will be able to remove with small force. However, when a photo-disintegrating resin is used, the required strength can only be maintained for about 2 to 3 months. Therefore, in crops that require a longer period before harvesting, the strength is required. However, the binding tape has already deteriorated and the strength is low, and there is a problem that it cannot play the role of the binding tape.

Moreover, the tape made from a film which consists of aliphatic polyester which has biodegradability is proposed (patent document 1). According to this, since the used tape can be decomposed in the soil, it is not necessary to remove it after use and collect it or the like. However, a tape made of aliphatic polyester has insufficient mechanical strength, and there is a problem that, for example, tearing or the like is likely to occur from a portion stopped with a staple needle during use.
In order to improve this, there is an example in which a film obtained by stretching a sheet of biodegradable aliphatic polyester is used as a binding tape (Patent Document 2). However, the tensile strength is temporarily improved by stretching, but the strength is lowered due to the deterioration of weather resistance, which may be easily broken.
On the other hand, a decomposable adhesive film using an adhesive layer on one side of a base film made of a lactic acid-based polymer such as a lactic acid hydroxycarboxylic acid copolymer is known (Patent Document 3). Not reached.

JP 7-47599 A JP-A-9-266729 JP-A-6-330001

  The present invention has sufficient strength to support and attract plants, and has sufficient weather resistance to maintain necessary strength until harvesting even when used for plants that take a long time to harvest, and harvesting. The strength decreases so that it can be easily shredded with a small force, and when it is buried in the soil, it decomposes naturally, so there is no need to clean up and it is suitable for use as a binding tape that has little impact on the environment. Another object is to provide a laminated paper and a binding tape using the laminated paper.

  The present invention has been made to achieve the above object, and the first feature is that a lactic acid-based aliphatic polyester containing 0.7 to 10% by weight of a lactic acid component is formed on both sides of a water-resistant paper substrate. It is a laminated paper for binding tapes laminated to a thickness of ˜35 μm.

  The second feature of the present invention is that the residual ratio of the wet tensile strength to the dry tensile strength of the water-resistant paper base material measured by a method according to JIS P8135 is 30% or more. The content is laminated paper for binding tape.

A third feature of the present invention is the laminated paper for a binding tape, wherein the basis weight of the water-resistant paper base is 40 to 90 g / m ² .

  A fourth feature of the present invention is the above-described laminated tape laminate paper obtained by melt-extruding a lactic acid-based aliphatic polyester onto a water-resistant paper base.

  A fifth feature of the present invention is a binding tape formed by cutting the laminated paper.

  A sixth feature of the present invention is a binding tape in which an adhesive or a pressure-sensitive adhesive is provided on one surface.

The laminated paper for bundling tape of the present invention is excellent in mechanical strength because the layer made of lactic acid-based aliphatic polyester is reinforced with paper fibers, preventing troubles such as tearing and tearing during bundling and use Is done.
In addition, since it is composed of a lactic acid-based aliphatic polyester and a paper base material, it is decomposed by microorganisms when buried in soil after use, so that it is environmentally friendly, and the trouble of cleaning up after use can be reduced.
Further, since a water-resistant paper substrate is used, the weather resistance is excellent, and it is difficult to be decomposed in normal air and is not easily deteriorated with time by sunlight. Accordingly, since the strength does not decrease much even after being exposed to sunlight after being fixed with a binding tape, the support tool and the plant can be suitably bound until harvest time.
If an adhesive layer or a pressure-sensitive adhesive layer is provided on one surface of a binding tape obtained by cutting such a laminated paper, the labor of the binding operation is simplified and the binding tape is excellent in usability.

The laminated paper for a binding tape of the present invention is formed by laminating a lactic acid-based aliphatic polyester containing 0.7 to 10% by weight of a lactic acid component to a thickness of 12 to 35 μm on both surfaces of a water-resistant paper substrate. Features.
The binding tape of the present invention is obtained by cutting the laminated paper, and is characterized in that an adhesive layer or a pressure-sensitive adhesive layer is provided on one surface of the binding tape.
In the present invention, the binding tape is used as a term including a support / attraction tape.

As a lactic acid-based aliphatic polyester containing lactic acid used in the present invention, the lactic acid unit is based on the weight of an aliphatic polyester composed of another dibasic acid and a diol (hereinafter sometimes simply referred to as polyester). , 0.7 to 10% by weight, preferably 0.8 to 8% by weight.
Examples of the lactic acid component include lactide and polylactic acid in which two molecules of lactic acid are cyclized, and lactic acid or lactide is preferable.
The polyester component consists of a dibasic acid and a diol. Examples of the dibasic acid component include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, and cyclohexanedicarboxylic acid. Two or more species may be used in combination. Of these, the preferred dibasic acid is succinic acid.
Examples of the diol include ethylene glycol, propylene glycol, 1,4-butylene glycol, 1,3-butylene glycol and the like, and these may be used alone or in combination of two or more. Of these, the preferred diol is 1,4-butylene glycol.

The ratio of the polyester component and the lactic acid component used is that the dibasic acid and the diol, which are polyester components, are easily equimolar to obtain a polymer resin. A lactic acid-based aliphatic polyester as a unit is preferably used.
For example, in the case of a lactic acid-based aliphatic polyester composed of succinic acid, 1,4-butanediol, and lactic acid, a polybutylene succinate resin having 2 units of lactic acid (2 mol%: 0.86 wt%) is synthesized with polyolefin, etc. Commercial products that have been confirmed to meet the voluntary standards (PL) for resin food containers and packaging are known. On the other hand, the upper limit of lactic acid is preferably 20 units (20 mol%: 7.96 wt%).
Moreover, the dibasic acid and the diol are known as lactic acid-based polyesters having an equimolar ratio to about 1.5 molar equivalents of excess diol. When this is applied to a lactic acid-based aliphatic polyester comprising succinic acid, 1,4-butanediol, and lactic acid, the amount of lactic acid is preferably about 0.7 to 10% by weight based on the units of dibasic acid and diol. About 8 to 8% by weight is more preferable. When the content of lactic acid in the lactic acid-based aliphatic polyester is out of the above range, the adhesiveness with a water-resistant paper substrate is deteriorated.

  In order to produce lactic acid-based polyester, dibasic acid, diol, lactic acid or lactide are mixed in a required amount and heated to distill off the water produced while refluxing the lactic acid component. In a more preferred method, dibasic acid and glycol are heated and mixed under a nitrogen stream, and water formed is distilled off to obtain an aliphatic polyester. This is a method for obtaining a lactic acid-based polyester by distilling off water produced by heating the obtained aliphatic polyester and the required lactide in the presence of toluene. Heating should be increased stepwise to promote water distillation, and finally stirred under reduced pressure. At this time, a small amount of lead acetate, titanium tetraisopropoxide, titanium tetrabutoxide, tin octoate, zinc octoate or the like can be added as a transesterification catalyst. The obtained lactic acid-based aliphatic polyester is a polymer having a polystyrene-reduced weight average molecular weight using GPC of preferably 5000 or more, more preferably 10,000 or more, and still more preferably 100,000 or more.

  In the lactic acid-based aliphatic polyester used in the present invention, it is possible to add usual additives used for modifying the resin. For example, an antioxidant such as 2,6-di-t-butyl-4-methylphenol and butylhydroxyanisole, and a heat stabilizer such as phosphate ester, isocyanate and carbodiimide can be added. In addition, processing aids such as metal soaps such as zinc stearate, magnesium stearate, calcium stearate, liquid paraffin, and lubricants such as ethylene bisstearyl amide can be used.

  The lactic acid-based aliphatic polyester obtained as described above is laminated on both sides of a paper substrate having water resistance. The thickness of the resin layer of the lactic acid aliphatic polyester to be laminated is 12 to 35 μm, preferably 15 to 30 μm. When the thickness of the resin layer is less than 12 μm, the adhesiveness to the paper substrate becomes insufficient. On the other hand, when the thickness exceeds 35 μm, it is unsuitable for bundling from the viewpoint of production cost.

  The properties when the laminated paper of the present invention is used for agricultural cultivation are required to have weather resistance as well as biodegradability. Ideally, it should have sufficient strength to induce binding during plant growth, and it must be easy to remove because it has deteriorated and deteriorated during harvesting. Although this differs depending on the environmental conditions to be used, specifically, with a tensile strength of 20 N or more in an accelerated weathering test of 160 hours (equivalent to about 8 months of outdoor exposure) for a width of 11 mm initially used as a binding tape. It is necessary to be present, and after that, it is preferable to decrease to about 1/2 in about one year of outdoor exposure. Such weather resistance of the laminated paper can be achieved by the water resistance of the paper substrate.

  General paper base materials such as kraft paper, fine paper, and glossy paper are inferior in strength when wet. Even when such a paper base material has a lactic acid-based aliphatic polyester resin layer laminated on both sides, weather resistance is required for outdoor use exposed to sunlight or wind and rain. The water resistance of the paper substrate can be increased by devising sizing such as coating or impregnation of wax or emulsion, or by providing a barrier layer.

  As a water resistance scale of the paper base that can be used in the present invention, wet tensile strength defined in JIS P8135 can be used. In JIS P8135, a paper base sample is usually immersed in water for 1 hour, and the ratio of the tensile strength immediately after immersion to the tensile strength in the dry state before immersion (hereinafter, this ratio is referred to as the residual ratio of tensile strength). Water resistance. For example, as an attractive binding tape when the period until harvest is about 8 months, a binding tape having suitable weather resistance can be obtained when the residual rate is preferably 20% or more, more preferably 30% or more. .

  Note that with the laminated paper in which both sides of the paper base material are laminated with lactic acid aliphatic polyester, the residual rate of the paper base material alone cannot be measured by the above method. Soaked into the paper substrate through the laminate layer or the cut surface of the sample, and then wet-peeled when one side of the laminate layer is fixed with an adhesive or adhesive and the other side is peeled off at an angle of 180 ° The residual ratio (ratio of wet peel strength to dry peel strength) can be measured from the strength and the peel strength when the dry sample laminate layer is peeled off in the same manner.

The thickness of the water-resistant paper base is expressed by basis weight, and the basis weight is not particularly limited in the present invention. However, in order to obtain an appropriate strength as a binding tape, usually 40 to 90 g / m ² is appropriate. It is.

  As a method of laminating a lactic acid-based aliphatic polyester on a paper substrate, the lactic acid-based aliphatic polyester is heated and melted with a uniaxial or biaxial screw extruder, extruded from a T die on a slit, and extruded into a curtain shape. The lactic acid-based aliphatic polyester is placed on the paper base fed out from the feeding roll, and the paper base and the lactic acid-based aliphatic polyester are both kept at a constant temperature and a rubber touch. The method of pinching with a roll can be illustrated.

  In order to laminate on both sides, it may be divided into two steps for each side, but using a line where the paper base is inverted from the melted resin extruded in a curtain form from two extruders by the so-called tandem method. May be separately sandwiched between rolls and laminated.

  In order to use the laminated paper obtained as described above as a binding tape, the laminated paper may be cut into an appropriate width and length. Preferably, it is in the form of a long tape having a width of about 0.5 to 5 cm and a length of about 5 to 100 m, which is wound around a paper core or the like to form a roll product. It may be cut into pieces.

An adhesive layer or a pressure-sensitive adhesive layer can also be provided on one surface of the binding tape of the present invention. Since such a binding tape is firmly bound by bonding together with an adhesive layer or an adhesive layer, the usability is excellent and the workability of binding is improved.
A release paper or a release film is laminated on the adhesive layer or the pressure-sensitive adhesive layer as necessary.

  The binding tape of the present invention can be favorably used as a support / attractive binding tape for agricultural and horticultural use to tie plant stems, branches, vines, etc. to a support in horticultural cultivation of vegetables, fruits, flowers, etc. In addition to such usage, harvested vegetables, fruits, flowers and the like can be bundled and used as various packaging materials.

  In addition, if supporting tools such as supporting nets are also made of a biodegradable material, the plant after harvesting fruits and the like is buried in the soil without separating these supporting tools and binding tape. It can be decomposed naturally or composted, and the labor of the work can be greatly reduced.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. In addition, this invention is not limited at all by these Examples.

Example 1
MOLZA water-resistant paper (basis weight 45 g / m ² , manufactured by MOLZA Co., Ltd.) was fed out from a paper base feeding machine. On the other hand, lactic acid-based aliphatic polyester (Mitsubishi Chemical Co., Ltd .: GSPla FZ91PN) was melt-extruded on both sides of the paper with a T-die having a die width of 400 mm of two 40 mm extruders and a slit interval of 0.8.
The extrusion temperature is set to 270 ° C., and the paper substrate is pressed with a cooling roll having a temperature of 20 ° C. and a rubber touch roll, and a resin layer (laminate layer) having a thickness of 20 μm is laminated at a processing speed of 25 m / min. The body was applied to both sides to obtain a double-sided laminated paper.
The physical properties of the paper substrate used and the resulting laminated paper were determined by the following method. The results are shown in Table 1.

Wet tensile strength test method:
According to JIS P8135,
(1) A paper substrate is cut into a sample having a width of 11 mm and a length of 150 mm.
(2) Immerse the sample in water for 1 hour.
(3) After removing the sample from the water, place it on the blotting paper, place another blotting paper on the sample, lightly press to remove excess water, and stack three sheets.
(4) Three layers are measured by the same method as the usual tensile strength measurement method.
(5) Separately, the tensile strength of the dried paper base material before immersion was measured by the same method as in (4) above, and the ratio of the wet tensile strength measured in (4) to the tensile strength of the dry paper base material Is calculated, and this percentage is expressed as a percentage to obtain the residual ratio.

Weather resistance test method:
(1) A laminate paper is cut into a width of 11 mm and a length of 150 mm to obtain a sample.
(2) The sample is immersed in water for 1 hour.
(3) The sample is subjected to a weather resistance test under the following exposure conditions using a sunshine carbon arc lamp type weather resistance tester.
Arc voltage: DC voltage 50V Arc current: AC voltage 60A
Black panel temperature: 63 ± 3 ° C Humidity: 50% RH
Rain spray time: 18 minutes / 120 minutes Rain spray pressure: 1.0 kg / cm ²
Rain spray amount: 2100 ± 100cc / min Irradiation time: 160 hours (equivalent to about 8 months of outdoor exposure)

Tensile strength measurement method:
The sample after the weather resistance test (after 160 hours and after 240 hours) is set so that the distance between the air chucks is unified to 10 cm, pulled at a test speed of 300 mm / min, and the load at break is measured.

Degradation test in soil:
The sample after the weather resistance test is buried in the soil of the horticultural field for 2 months, and then the decomposition state is observed to evaluate whether the sample can be collected (undecomposed) or not (decomposed).

Comparative Example 1
A double-sided laminated paper was produced in the same manner as in Example 1, except that the water-resistant paper base material was changed to a cur-packed WS processed kraft paper (basis weight 73 g / m ² , manufactured by Chuetsu Pulp Industries).
The physical properties of the used paper substrate and the obtained laminated paper were determined in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2
A double-sided laminated paper was produced in the same manner as in Example 1 except that the water-resistant paper substrate was changed to unbleached kraft paper (basis weight 50 g / m ² , manufactured by Chuetsu Pulp Industries).
The physical properties of the used paper substrate and the obtained laminated paper were determined in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 3
A double-sided laminated paper was produced in the same manner as in Example 1 except that the water-resistant paper base material was changed to single gloss bleached kraft paper (basis weight 50 g / m ² , manufactured by Daio Paper).
The physical properties of the used paper substrate and the obtained laminated paper were determined in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 4
Single-sided laminated paper was produced in the same manner as in Example 1 except that the resin layer was applied only to one side of the paper substrate and the thickness of the resin layer was changed to 40 μm.
The physical properties of the used paper substrate and the obtained single-sided laminated paper were determined in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 5
A double-sided laminated paper was produced in the same manner as in Example 1 except that the resin layer was changed to LDPE (manufactured by Dow Chemical Company: NUC8009).
The physical properties of the used paper substrate and the obtained laminated paper were determined in the same manner as in Example 1. The results are shown in Table 1.

According to the results in Table 1, when a water-resistant paper substrate having a residual rate of 20% or more is used, the tensile strength after a 160-hour weather resistance test (equivalent to 8 months after outdoor exposure) is 20 N / 11 mm or more, and until the harvest period It can be seen that the strength is maintained and biodegradation in the soil occurs.
On the other hand, when a paper base with poor water resistance with a residual rate of less than 20% is used, or when resin is laminated on only one side, biodegradation in the soil occurs, but the strength remains until the harvesting season. It cannot be kept or is insufficient.
Moreover, the laminated paper made of polyethylene was inferior in weather resistance and soil degradation.

  As described above, the laminated paper and the binding tape for the binding tape according to the present invention are laminated with the lactic acid aliphatic polyester laminated on both surfaces of the water-resistant paper base material, so that the mechanical strength is excellent and appropriate. It has excellent weather resistance and can be biodegradable in soil, and is useful as a laminated paper for a binding tape and a binding tape.

Claims (6)

  A laminated paper for a binding tape, wherein a lactic acid-based aliphatic polyester containing 0.7 to 10% by weight of a lactic acid component is laminated to a thickness of 12 to 35 μm on both surfaces of a water-resistant paper substrate.   The binding tape according to claim 1, wherein the residual ratio of the wet tensile strength to the dry tensile strength of the water-resistant paper base material measured by a method according to JIS P8135 is 30% or more. Laminated paper. 3. The laminated paper for binding tape according to claim 1, wherein the basis weight of the water-resistant paper base is 40 to 90 g / m ² .   The laminated paper for a binding tape according to any one of claims 1 to 3, wherein the lactic acid-based aliphatic polyester is melt-extruded on a water-resistant paper substrate.   A binding tape obtained by cutting the laminated paper according to any one of claims 1 to 4.   6. The binding tape according to claim 5, wherein an adhesive layer or a pressure-sensitive adhesive layer is provided on one surface.