JP4676791B2 - A sheet for fumigation of pine worms with high gas barrier properties - Google Patents

Description

  The present invention relates to a biodegradable resin sheet that uses a biodegradable resin and has a high gas barrier property, and is preferably used as a cover sheet for fumigation of pests such as pine worms.

In recent years, withering damage to forests such as pine forests by pine weevil such as pine weevil, pine beetle, and pine beetle is increasing, and pine growth is seriously damaged.
Also, when transporting various large products, etc., wood pallets are used for transportation by forklifts, but there are many cases where harmful pests lurk in these wood pallets, and the wood pallets are transported to other countries as they are. This results in the migration of such pests to other countries, and has problems that lead to the destruction of the country's natural environment. In particular, wood pallets for imported products transported from Japan and the United States often have pine worms mixed as such pests. It is desired.

  In order to prevent such damage caused by pine worms, the dead tree of pine trees damaged by pine worms is covered and enclosed with a plastic barrier sheet, and methyl isothiocyanate (MITC), an active ingredient for fumigation, is used. Processing with fumigant is carried out. Even in the case of disinfection of wood, in many cases, the wood just after cutting is piled up outdoors, covered with a plastic barrier sheet, hermetically enclosed, and MITC is fumigated.

  As such a fumigation barrier sheet, a polyethylene film or a polyvinyl chloride film is used. By the way, the fumigation of pests such as pine worms is over a long period of time of one month or more, and when the chemical fumigation is completed, the barrier sheet for fumigation is discarded. In many cases, chemical fumigation is carried out in forests with dead pine trees or forests where timber has been cut, so used fumigation sheets are incinerated on the spot. Therefore, incineration disposal is not preferable, and therefore, a fumigation sheet using a biodegradable resin is being adopted.

  For example, since the biodegradable resin single film has poor gas barrier properties against fumigant, a base paper having an air permeability of a certain value or more made of a cellulose component is used to compensate for the shortage. A coating sheet for fumigation disinfection in which a plastic resin layer is laminated has been proposed (Patent Document 1). However, the sheet laminated with this paper and biodegradable resin has a high gas barrier property, but easily breaks when caught on a tree branch or the like, and the sheet itself is not transparent, so that the coated interior cannot be confirmed. There is.

  In order to improve this point, a film made of only biodegradable resin without using a base paper has been proposed (Patent Document 2). As a biodegradable resin film, a biodegradable resin film having a high gas barrier property is described by a combination of an aliphatic aromatic polyester and an aliphatic polyester. , Using polybutylene adipate terephthalate (PBAT), which is a copolymer of 1,4-butanediol, adipic acid and terephthalic acid, and comprising only a combination of polybutylene succinate (PBS) as an aliphatic polyester, No biodegradable resin film based on a combination of other biodegradable resins has been studied, and no specific gas barrier property comparison has been made. Even aliphatic polyesters having biodegradability have different gas barrier properties depending on the resin, and are not all excellent.

In Patent Document 2, the gas barrier property of a biodegradable resin film using a combination of polybutylene adipate terephthalate (PBAT) and polybutylene succinate (PBS) is compared with that of a polyvinyl chloride (PVC) film. However, it is well known that a soft PVC film containing a large amount of plasticizer, such as a fumigation film, generally has a low gas barrier property. When compared with a widely used polyethylene film, the gas barrier property Is not necessarily high and does not have sufficient gas barrier properties.
Japanese Patent No. 3557370 JP 2003-284478 A

  In view of the above problems, the present invention provides a biodegradable resin sheet having extremely high gas barrier properties and sufficient physical properties and moldability as a resin sheet for fumigation of pine worms. The task is to do.

  In order to solve such problems, the present inventor has intensively studied, and as a result, an aliphatic aromatic polyester, a polyethylene succinate as an aliphatic polyester, and an aliphatic polyester having a long chain branch as a biodegradable resin. When combined, the permeability of methyl isothiocyanate (MITC) gas, which is a fumigant for pine worms, can be reduced, and a biodegradable resin film having extremely good gas barrier properties can be obtained. Also, the moldability as a fumigation sheet was good, and it was confirmed that the obtained fumigation sheet had sufficient physical properties, and the present invention was completed.

  Accordingly, the basic aspect of the present invention is blended in a composition ratio of 10 to 89 parts by weight of an aliphatic aromatic polyester, 10 to 89 parts by weight of a polyethylene succinate and 1 to 80 parts by weight of an aliphatic polyester having a long chain branch. It is a biodegradable pinworm fumigation sheet having a high gas barrier property, comprising a biodegradable resin and having a methyl isothiocyanate (MITC) gas permeability of 0.8 or less.

  That is, the present invention relates to an aliphatic aromatic polyester that is a polycondensate of a dicarboxylic acid component composed of an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid and a diol component composed of an aliphatic diol, an aliphatic dicarboxylic acid and an aliphatic diol. Among the aliphatic polyesters produced by melt polymerization of polyethylene, biodegradable resin obtained by mixing polyethylene succinate (PES) and aliphatic polyester having a long chain branch in combination, and forming such a mixed resin into a film The film is characterized in that it is a biodegradable resin film having extremely good gas barrier properties, good moldability, and satisfactory physical properties as a fumigation sheet.

The sheet for fumigation of pine worms provided by the present invention is not torn when the sheet is covered with wood, and the use of a biodegradable resin film makes it possible to recover the sheet after fumigation. The processing cost of the collected sheets can be reduced.
In addition, compared to conventional biodegradable resin sheets with poor gas barrier properties, the gas barrier properties are extremely high, and it has an extremely excellent effect in that it can prevent sublimation and escape of drugs during fumigation. Demonstrate. Therefore, the chemical fumigation work is performed efficiently, and the damage of the pine worms can be minimized.
Furthermore, the biodegradability is also good, and there is an advantage that a fumigating resin sheet that is friendly to the global environment and does not generate harmful gases due to incineration disposal is provided.
Furthermore, the biodegradable resin sheet of the present invention has extremely good moldability. For example, the biodegradable resin sheet can be easily processed into a sheet by a conventional inflation molding machine, and the processing speed can be increased. , Efficient production becomes possible.

  The biodegradable resin used in the biodegradable resin sheet for fumigation of pine worms provided by the present invention includes aliphatic aromatic polyesters, polyethylene succinates as aliphatic polyesters, and aliphatics having long chain branches It is a mixture of biodegradable resins in which polyester is combined at a constant composition ratio.

  The aliphatic aromatic polyester is an aliphatic aromatic polyester that is a polymerization condensate of a dicarboxylic acid component composed of an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid and a diol component composed of an aliphatic diol. For example, an aliphatic aromatic polyester obtained by polymerizing a polycondensate of a dicarboxylic acid component composed of adipic acid and terephthalic acid and a diol component composed of 1,4-butanediol with a polyfunctional isocyanate is preferable. Other diol components include 2,3-butanediol, 1,3-butanediol, 1,4-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 1,6-hexanediol, neo Examples include pentyl glycol, ethylene glycol, diethylene glycol and the like.

  Examples of other dicarboxylic acid components include succinic acid, suberic acid, sebacic acid, dodecanoic acid, succinic anhydride, and adipic anhydride. Two or more of these dicarboxylic acids may be used in combination.

  More specifically, examples of the aliphatic aromatic polyester include polybutylene adipate terephthalate (PBAT), polybutylene succinate adipate terephthalate, and polytetramethylene adipate terephthalate. Among them, polybutylene adipate terephthalate (PBAT) is preferable. Can be used for

  On the other hand, the polyethylene succinate used in the present invention is a high molecular weight polyethylene succinate obtained by esterifying succinic acid with an excess of ethylene glycol and then polycondensing at a high temperature.

  Specifically, first, succinic acid and ethylene glycol are esterified. Examples of the succinic acid used in the reaction include ester-forming derivatives such as succinic anhydride and dialkyl succinate, and other dicarboxylic acids such as oxalic acid, as long as the physical properties of the resulting polyethylene succinate are not impaired. An ester-forming derivative such as acid, adipic acid, glutaric acid, suberic acid, sebacic acid, dodecanoic acid and its acid anhydride, dialkyl ester and the like can also be used in combination.

  In addition, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid can be used in combination as long as the biodegradability is not impaired.

  Ethylene glycol also includes ester-forming derivatives such as ethylene oxide, and other diols such as 1,4-cyclohexanedimethanol, 1,4 within the range that does not impair the physical properties of the resulting polyethylene succinate. -Butanediol, neopentyl glycol, diethylene glycol, propylene glycol, triethylene glycol, neopentyl glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, or ester-forming derivatives thereof can be used in combination. Furthermore, oxycarboxylic acid, polyvalent carboxylic acid, polyhydric alcohol and the like can be used in combination.

  In preparation of the polyethylene succinate used in the present invention, it is necessary that the charging ratio of succinic acid and ethylene glycol is 2 mol or more of ethylene glycol with respect to 1 mol of succinic acid. Preferably, 2 to 5 moles of ethylene glycol are used per mole of succinic acid. If the ethylene glycol charge ratio is less than 2 mol, a high molecular weight polyethylene succinate cannot be obtained, and the effect does not change even if it exceeds 5 mol, but the amount of ethylene glycol recovered increases, which is preferable. is not.

  The esterification conditions are preferably 120 to 250 ° C. for 1 to 10 hours, particularly 180 to 240 ° C. for 2 to 5 hours, atmospheric pressure, inert gas flow, particularly nitrogen. It is better to react in a gas stream.

  After the esterification reaction is completed, it is then necessary to subject the obtained product to a polycondensation reaction at a high temperature of at least 280 ° C, and particularly preferably 280 to 350 ° C. If the temperature at this time is less than 280 ° C., the time required for polycondensation becomes long and the polycondensation does not proceed sufficiently, so that a high molecular weight polyethylene succinate cannot be obtained.

  The conditions for the polycondensation reaction are preferably 1 to 10 hours under a reduced pressure of 0.01 to 10 mmHg, more preferably 1 to 5 hours under a reduced pressure of 0.1 to 1 mmHg.

  In the polycondensation reaction, a phosphorus compound may be added. Examples of the phosphorus compound include phosphoric acid, phosphoric anhydride, polyphosphoric acid, metaphosphoric acid, pyrophosphoric acid, phosphorous acid, hypophosphorous acid, and tripolyphosphoric acid. Or their metal salts, ammonium salts, chlorides, ester compounds and the like. In addition, a spirophosphate compound typified by bis (2,4-dibutylphenyl) pentaerythritol diphosphate can also be used. Particularly preferred are phosphoric acid, polyphosphoric acid, metaphosphoric acid, bis (2,4-dibutylphenyl) pentaerythritol diphosphate, and pyrophosphoric acid. These may be used alone or in combination of two or more. . The addition amount of the phosphoric acid compound is preferably 0.001 to 1 part by weight, more preferably 0.01 to 1 part by weight per 100 parts by weight of the polyethylene succinate to be produced.

  On the other hand, the aliphatic polyester having a long chain branch used in the present invention has a melting point of 70 to 190 ° C., and mainly contains an aliphatic glycol (including a cyclo ring) and an aliphatic dicarboxylic acid (or an anhydride thereof). An aliphatic polyester having a long chain branch synthesized by condensation using a suitable polyfunctional coupling agent to a polyester prepolymer having a number average molecular weight (Mn) of 5000 or more, preferably 10,000 or more obtained as a main component. is there.

  Examples of such glycols include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, decamethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol and the like. Ethylene oxide can also be used. These glycols may use 2 or more types together.

  Examples of the aliphatic dicarboxylic acid (or its anhydride) include succinic acid, adipic acid, suberic acid, sebacic acid, dodecanoic acid, succinic anhydride, and adipic anhydride. Two or more of these aliphatic dicarboxylic acids (or their anhydrides) may be used in combination.

  Examples of the polyfunctional coupling agent include polyfunctional isocyanates, oxazolines, diepoxy compounds, and acid anhydrides. When a polyfunctional isocyanate is used as the polyfunctional coupling agent, the polyester prepolymer becomes a polyester that forms a long chain structure via a urethane bond. When an oxazoline, diepoxy compound, or acid anhydride is used as the polyfunctional coupling agent, the polyester prepolymer becomes a polyester that forms a chain structure via an ester bond.

  Examples of the polyfunctional isocyanate include trimethylolpropane / hexamethylene diisocyanate / adduct, hexamethylene diisocyanate cyclic trimer or hexamethylene diisocyanate / water / adduct.

  In the preparation of the polyester prepolymer, a trifunctional or tetrafunctional polyhydric alcohol or a trifunctional or tetrafunctional oxycarboxylic acid and / or a trifunctional or tetrafunctional polycarboxylic acid is added as a third component. Can do. Examples of such trifunctional or tetrafunctional polyhydric alcohols include trimethylolpropane, glycerin, and pentaerythritol. Trifunctional or tetrafunctional oxycarboxylic acid and / or trifunctional or tetrafunctional polyvalent carboxylic acid include trimesic acid, propanetricarboxylic acid, trimellitic anhydride, pyromellitic anhydride, benzophenone teracarboxylic acid anhydride And cyclopentanetetracarboxylic acid, malic acid, citric acid and tartaric acid.

  As a specific example of the biodegradable aliphatic polyester having a long chain branch used in the present invention, an aliphatic polyester “Bioleno # 1903” manufactured by Showa Polymer Co., Ltd. is preferable. As other biodegradable aliphatic polyester having a long chain branch, polycaprolactone or polylactic acid can also be used.

  In the biodegradable resin sheet for fumigation of pine worms provided by the present invention, as a biodegradable resin, an aliphatic aromatic polyester, a polyethylene succinate, and an aliphatic polyester having a long chain branch are in a certain composition ratio. A mixture of combined biodegradable resins is used. The composition ratio is 10 to 89 parts by weight of aliphatic aromatic polyester, particularly polybutylene adipate terephthalate (PBAT), 10 to 89 parts by weight of polyethylene succinate, and 1 to 80 parts by weight of aliphatic polyester having a long chain branch. Therefore, the permeability of the MITC gas, which is a fumigant for pine worms, can be reduced, the gas barrier property is extremely good, and the physical properties and moldability as a fumigation sheet are also obtained. A good biodegradable resin film can be obtained.

  When the polybutylene adipate terephthalate (PBAT) is less than 10 parts by weight, the tearable physical properties of the resulting biodegradable resin film are not improved and the film is easily broken, which is not preferable. Moreover, when the polyethylene succinate is less than 10 parts by weight, the improvement of gas barrier property of the obtained biodegradable resin film is not observed, and it is not preferable.

  Moreover, the addition of the aliphatic polyester having a long chain branch improves the processing characteristics when the mixture of biodegradable resins is processed into a sheet. Therefore, if the addition amount is less than 1 part by weight, the processability into a sheet shape is not improved.

  In the present invention, the gas barrier property of the biodegradable resin film thus obtained is extremely good, and the permeability of methyl isothiocyanate (MITC) gas, which is a fumigant for pine worms, is 0.8 or less. be able to.

  The permeability of methyl isothiocyanate (MITC) gas in the present invention means that two box-shaped containers each provided with a vent hole on one surface are connected to each other between the surfaces having holes, and a resin therebetween. After sandwiching the film and putting methyl isothiocyanate (MITC) in one container and leaving it in that state for 24 hours, the MITC gas concentration in both containers (drug-feeding tank and drug-permeating tank) was set to GC-FID. And the gas permeability obtained by the following equation.

  In the biodegradable pine worm fumigation resin sheet provided by the present invention, various additives can be appropriately blended within a range that does not impair the biodegradability. Examples of such additives include inorganic fillers, organic fillers, ultraviolet absorbers, plasticizers, pigments, antioxidants, lubricants, antifogging agents, antistatic agents, and light stabilizers. These additives can be appropriately selected in kind and amount in a range not impairing the biodegradability of the target resin sheet.

  In particular, the biodegradable resin sheet for fumigation of pine worms provided by the present invention is often used outdoors as a fumigation sheet. Therefore, in order to prevent decomposition by ultraviolet rays, an ultraviolet absorber is used. It is preferable to add it. Examples of such an ultraviolet absorber include an ultraviolet absorber that is generally added as an agricultural resin sheet.

  In addition, the inorganic filler added to the resin component is added to increase the melt tension with respect to the resin component and to make the sheet solid and to improve workability. Such inorganic fillers include those known as resin additives, specifically, calcium carbonate, magnesium hydroxide, aluminum hydroxide, barium sulfate, mica, talc, kaolin, feldspar, quartz, clay. , Silica, hydrotalcite and the like. These inorganic fillers can be used alone or in admixture of two or more. The amount added is about 0.1 to 10 parts, and if it is too large, the transparency of the resulting sheet is impaired, and the elongation at the time of melting of the resin becomes small, so that there is a possibility that it cannot be stretched. Moreover, when there is little addition amount, the target effect cannot be acquired.

  The antioxidant is added to prevent decomposition of the resin at that time because heat is applied during processing. That is, it is added in order to prevent molecular cutting of the resin component due to heat during processing and generation of a low molecular component and adhesion to the roll. As such an antioxidant, general antioxidants such as hindered phenol antioxidants and phosphate ester antioxidants can be used. The addition amount of the antioxidant is about 0.01 to 3 parts. If the amount added is large, the product will bloom, and if the amount is small, no effect will be obtained.

  In order to improve the releasability between the metal roll and the resin sheet, a more general lubricant can be added. As such a lubricant, any of those used for compounding a resin composition can be used. For example, barium stearate, calcium stearate, zinc stearate, aluminum stearate, magnesium stearate, Fatty acid metal salts (metal soap) such as sodium palmitate, waxes such as phosphoric acid esters, polyethylene wax, and montanic acid wax, fatty acid amides such as ethylenebisstearic acid amide and erucic acid amide, glycerin monostearate, sorbitan monooleate, etc. And fatty acid esters. Two or more of these lubricants may be used in combination.

  The biodegradable resin sheet of the present invention is based on a biodegradable resin composed of an aliphatic aromatic polyester, a polyethylene succinate, and an aliphatic polyester having a long-chain branch. Polyester may be added.

  The resin sheet for fumigation of pine worms provided by the present invention can be formed by a conventional film forming machine, such as polybutylene adipate terephthalate (PBAT) polyethylene succinate and long chain branching. It is possible to form a film on an inflation molding machine after dry blending an aliphatic polyester having a suitable resin additive if necessary. Also, molding by a T-die extruder or calendar method is possible. Furthermore, lamination with other resin films by a multilayer extruder or lamination is also possible if desired.

  The biodegradable pine worm fumigation resin sheet of the present invention thus obtained has a desired thickness of about 0.03 to 0.3 mm, but considering the handleability and biodegradability, it is 0.05 to A thickness of about 0.15 mm is preferred. Such a resin sheet, as a wood fumigation sheet for extermination of pine worms, has excellent gas barrier properties and quality, and is decomposed in a short period of time by microorganisms and the like present in the soil. Even if it is disposed of, it has excellent characteristics that it does not harm the natural environment.

  Hereinafter, the present invention will be described in more detail with reference to experimental examples, but the present invention is not limited to these examples.

Examples 1-5 / Comparative Examples 1-6
A biodegradable resin sheet having a thickness of 0.1 mm was obtained by an inflation molding machine using the resin blending components shown in Table 1 below.

  About each obtained sheet | seat, the MITC gas permeability and the tear strength of the film were evaluated. The results are summarized in Table 1.

* 1: Polybutylene adipate terephthalate: Ecoflex (manufactured by BASF)
* 2: Polyethylene succinate: Lunar SE-P5000 (Nippon Shokubai Co., Ltd.)
* 3: Long-chain branched polybutylene succinate: Bionore # 1903 (manufactured by Showa Polymer Co., Ltd.)
* 4: Polybutylene succinate (not long chain branch): Bionore # 1001 (Showa Polymer Co., Ltd.)
* 5: Low density polyethylene: Petrocene 176R (Tosoh Corporation)

* 6: Formability was evaluated according to the following criteria.
That is, in the inflation molding, the stability of bubbles was visually evaluated.
○: Stable.
X: Bubbles fluctuate and are unstable.

* 7: MITC gas permeability was measured by the following method.
Two box-shaped containers with vent holes on one side are connected to each other through holes, a resin film is sandwiched between them, and methyl isothiocyanate (MITC) is placed inside one container. After leaving in the state for 24 hours, the MITC gas concentration in both containers (drug supply tank and drug permeation tank) was measured by GC-FID, and the gas permeability was determined by the following equation.

* 8: The tear strength was evaluated by the following test.
A 10 mm incision was made in the longitudinal direction of the test film and it was torn by hand, and the tearing state was evaluated by the following evaluation items.
○: A force is required to tear, and the cut surface is wavy.
X: It tears easily and a cut surface is linear.

  As can be seen from the results shown in the table, it is understood that the biodegradable resin sheet for fumigation of pine worms of the present invention exhibits good high gas barrier properties. In addition, it is understood that the film has good moldability, and also has a high tear strength, which is particularly preferable when used outdoors.

  As described above, the biodegradable resin sheet for fumigation of pine worms provided by the present invention has a high gas barrier property compared to a conventional biodegradable resin sheet with poor gas barrier properties, Further, it has excellent moldability and physical properties as a fumigation sheet. Therefore, as a biodegradable resin sheet for wood fumigation, it is possible to prevent the sublimation and escape of chemicals at the time of fumigation.

Furthermore, since it is made of a biodegradable resin sheet, it is possible to save the labor of collecting the sheet after fumigation, and to provide a resin sheet that is friendly to the global environment and does not generate harmful gases due to incineration. Has advantages.

Claims (2)

  It is a biodegradable resin blended in a composition ratio of 10 to 89 parts by weight of an aliphatic aromatic polyester, 10 to 89 parts by weight of a polyethylene succinate and 1 to 80 parts by weight of an aliphatic polyester having a long chain branch. Biodegradable pine worm fumigation sheet with high gas barrier properties. 2. The biodegradable pinworm fumigation sheet having high gas barrier properties according to claim 1, wherein the permeability of methyl isothiocyanate (MITC) gas is 0.8 or less.