JPH11320594A - Polylactic acid resin sheet and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polylactic acid resin sheet which shows outstanding metallic roll release properties and can be produced very economically and further can deal with an environmental problem, and a method for manufacturing the polylactic acid resin sheet. SOLUTION: This polylactic acid resin sheet is obtained by calender-molding a resin composition consisting of 0.05-2.95 pts.wt. each silicone and lubricant which fall within the range of the total 3.0 or less pts.wt. added to be blended with 100 pts.wt. polylactic acid resin. When calender-molding the blend, the moisture content of the polylactic acid resin and the resin composition is 2.0% or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polylactic acid resin sheet formed by calendering a resin composition which biodegrades in a natural environment and a method for producing the same. The present invention relates to a tray sheet for storing, transporting, and storing products, lenses, and the like, a carrier tape sheet for packaging electronic components, and a base sheet for a magnetic card and an IC card.

[0002]

2. Description of the Related Art Conventionally, sheets for trays for storing, transporting and storing OA equipment, AV equipment, household electric appliances, lenses, etc., sheets for carrier tape for wrapping electronic components, or for magnetic cards and IC cards As the base sheet, a thermoplastic resin sheet such as a polyvinyl chloride resin sheet, a polystyrene resin sheet, or a polyethylene terephthalate resin sheet has been used. Sheets or molded products made of these resins have physical properties as tray sheets that are suitable for storage, transportation, and storage during use due to environmental issues, and sheets that decompose naturally in a natural environment after use Requested.

[0003] In recent years, biodegradable resins that are naturally decomposed in natural environments such as soil, fresh water, and seawater have been proposed, and various studies have been made toward their practical use. For example, as a biodegradable resin, a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate, a polylactic acid resin, a polyhydroxyalkanoate resin such as a polycaprolactone resin, and polyethylene succinate;
And polyalkyl alkanoate resins such as polybutyl succinate and polybutyl succinate adipate.

[0004]

As a method for forming these biodegradable resins into a sheet, there are an extrusion molding method and a calender molding method. I have. This is because the processing by the calender molding method is difficult in sheet processing because the releasability of the molten resin from the calender metal roll is poor. In particular, when the thickness of the resin sheet to be obtained is reduced, the calendering method further deteriorates the releasability of the resin sheet from the metal roll, so that it is extremely difficult to process the thin resin sheet.

An object of the present invention is to provide a polylactic acid-based resin sheet which has excellent metal roll releasability when formed by a calendering method, can be produced extremely economically, and can cope with environmental problems. It is to provide a manufacturing method thereof.

[0006]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, by adding a specific amount of silicone and a lubricant to a polylactic acid-based resin, the object thereof has been achieved. The inventors have found what can be achieved, and have completed the present invention. That is, in the present invention, silicone and a lubricant are added and blended in a range of 0.05 to 2.95 parts by weight, and a total amount of 3.0 parts by weight or less, based on 100 parts by weight of the polylactic acid-based resin. Is a polylactic acid-based resin sheet obtained by subjecting a resin composition to calender molding.
Further, when the above resin composition is melted and calendered, the water content of the polylactic acid-based resin and the resin composition is set to 2.
By performing the treatment at 0% or less, hydrolysis of the ester bond between the polylactic acid-based resin and the resin composition is suppressed, and the strength of the molded product can be sufficiently maintained.

As described above, the polylactic acid-based resin sheet of the present invention is obtained by calender molding a polylactic acid-based resin composition containing a polylactic acid-based resin, silicone and a lubricant.
It is a sheet that has excellent mechanical properties, can be produced extremely economically, and has good biodegradability and is good for the natural environment.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The polylactic acid-based resin used in the present invention is an aliphatic polyester containing a lactic acid unit. These include polylactic acid, copolymers of lactic acid and other hydroxycarboxylic acids, lactic acid, aliphatic polyesters composed of aliphatic polycarboxylic acids and aliphatic glycols, and mixtures thereof.

The above-mentioned polylactic acid is obtained by dehydrating and condensing L-lactic acid, D-lactic acid or a mixture of L-lactic acid and D-lactic acid. Preferably, lactide which is a cyclic dimer of lactic acid is used. It is obtained by ring-opening polymerization. Physical properties,
From the viewpoint of heat resistance and availability, the content of the L-form is preferably 85% or more, and more preferably 95% or more. Lactide includes L-lactide which is a cyclic dimer of L-lactic acid, D-lactide which is a cyclic dimer of D-lactic acid, and meso-lactide in which D-lactic acid and L-lactic acid are cyclically dimerized. There is DL-lactide which is a mixture of polylactic acid. Polylactic acid is obtained by ring-opening polymerization of one or more of these. The reason that the ring-opening polymerization of lactide is preferable is that lactide is easily polymerized and a product having a high degree of polymerization is easily obtained. Polylactic acid has a weight average molecular weight of 20,000 to
1,000,000, especially 50,000-500,
000 is preferred. If the weight average molecular weight is less than 20,000, practical properties as a sheet cannot be obtained, which is not preferable. On the other hand, when the weight average molecular weight exceeds 1,000,000, the formability of the sheet is poor.

In the copolymer of lactic acid and another hydroxycarboxylic acid, other hydroxycarboxylic acids include, for example, glycolic acid, dimethyl glycolic acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, -Hydroxypropanoic acid, 3-hydroxypropanoic acid, 2-hydroxyvaleric acid, 3-hydroxyvaleric acid,
4-hydroxyvaleric acid, 5-hydroxyvaleric acid, 2-hydroxycaproic acid, 3-hydroxycaproic acid, 4-
Hydroxycaproic acid, 5-hydroxycaproic acid, 6
-Hydroxycaproic acid, 6-hydroxymethylcaproic acid and the like, and cyclic esters other than lactide include glycosides, β-methyl-δ-valerolactone,
γ-valerolactone, ε-caprolactone and the like. The molar ratio of lactic acid units contained in the copolymer is at least 50 mol%, preferably at least 80 mol%. If the molar ratio is less than 50 mol%, the sheet strength and biodegradability are undesirably reduced.

In the aliphatic polyester comprising lactic acid, aliphatic polycarboxylic acid and aliphatic glycol, examples of the aliphatic polycarboxylic acid include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, and azelaic acid. , Undecandioic acid, dodecandioic acid and the like and anhydrides thereof. As the aliphatic glycol, for example,
Ethylene glycol, diethylene glycol, 1,2-
Propanediol, 1,3-propanediol, 1,3
-Butanediol, 1,4-butanediol, 2,3-
Butanediol, 1,5-pentanediol, 1,6-
Hexanediol, neopentyl glycol, tetramethylene glycol, 1,4-cyclohexanedimethanol and the like can be mentioned.

[0012] The amount of residual monomer in the polylactic acid resin used in the present invention is 5,000 ppm or less, preferably 3,0 ppm or less.
It is not more than 00 ppm. This residual monomer is 5,000
If it exceeds ppm, it becomes difficult to peel off the resin sheet from the metal roll, which is not preferable. Since the polylactic acid-based resin is difficult to peel off from the calender roll, when forming a sheet, the silicone and the lubricant are each added in an amount of 0.05 to 2.95 parts by weight, preferably 0 to 100 parts by weight of the polylactic acid-based resin. 0.1 to 2.50 parts by weight, and the total amount thereof is 3.0 parts by weight or less.
If the proportion of each of these silicones and lubricants is less than 0.05 parts by weight, the effect of the addition is insufficient and sufficient releasability from the metal roll cannot be obtained, and it is difficult to form a sheet by a calender method. On the other hand, if the proportion of each of them exceeds 2.95 parts by weight, a bleeding phenomenon occurs in which the silicone and the lubricant float out, which adversely affects the appearance and the mechanical properties. On the other hand, if the total amount of the silicone and the lubricant exceeds 3.0 parts by weight, the melt-kneaded product is not transferred to the calender roll, and the sheet cannot be formed.

The silicones used here are silicones such as dimethyl silicone and methyl phenyl silicone and modified silicones. As modified silicone,
For example, methylstyryl-modified silicone, alkyl-modified silicone, methacrylic acid-modified silicone, polyether-modified silicone, higher fatty acid-modified silicone, fluorine-modified silicone, and the like. Alkyl-modified silicones are preferably employed. These exemplified silicones and modified silicones have a viscosity at 25 ° C. of 100 to 10,000 cSt when the Ostwald method is used as a viscosity measurement method.
Are used. This viscosity is 100 cS
When it is less than t, peeling from the calender roll becomes difficult, which is not preferable. On the other hand, if it exceeds 10,000 cSt, handling becomes difficult, which is not preferable.

Examples of the lubricant used in the present invention include fatty acids such as lauric acid, myristic acid, stearic acid, oleic acid and behenic acid, and those having 12 to 12 carbon atoms such as lead stearate, zinc stearate, calcium stearate and calcium hydroxystearate. 20 aliphatic metal salts, zinc stearate / barium stearate complex, lead stearate / calcium stearate complex,
Aliphatic amides such as oleic acid amide, stearic acid amide, erucic acid amide, lauric acid amide, palmitic acid amide, behenic acid amide, ricinoleic acid amide, pentaerythritol mono / diester, pentaerythritol-tetrastearate, dipentaerythritol hexa Stearate, pentaerythritol-adipic acid-stearate / complex ester (trade name: RIQUESTER E)
W-200, RIQUESTER EW-250, manufactured by Akishima Chemical Industry Co., Ltd.), dipentaerythritol-adipic acid-stearic acid complex ester (trade name: RIQUESTER EW-10)
0, manufactured by Akishima Chemical Industry Co., Ltd.).

According to the present invention, a polyalkylalkanoate resin, a polyhydroxyalkanoate resin, or a filler may be added in addition to the above components to such an extent that the mechanical properties of the polylactic acid resin sheet are not impaired. Good. The usable polyalkylalkanoate-based resin may be any resin that contains an aliphatic polycarboxylic acid or a derivative thereof and an aliphatic diol as components and has biodegradability. The weight average molecular weight of the polyalkyl alkanoate resin is 10
When the weight average molecular weight is less than 100,000, practical properties as a sheet cannot be obtained, which is not preferable. On the other hand, when the weight average molecular weight exceeds 300,000, production is difficult and not practical.

The aliphatic polycarboxylic acid, which is a component of the polyalkylalkanoate resin, includes:
For example, malonic acid, succinic acid, glutaric acid, adipic acid, pyromellitic acid, azelaic acid, sebacic acid, undecandioic acid, dodecanedioic acid, anhydrides and derivatives thereof, and at least one of these. Is selected.

Examples of the aliphatic diol include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, and 1,3-propanediol.
Butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, cyclohexamethylene glycol, and the like. At least one is selected. Both have 2 carbon atoms
Compounds having up to 20 alkylene, cyclocyclic or cycloalkylene groups, produced by condensation polymerization.
In order to improve the melt strength, an aliphatic carboxylic acid, alcohol or oxycarboxylic acid having three or more functional groups may be used for providing a long-chain branched structure in the molecular chain. Examples of the component having three or more functional groups include malic acid, tartaric acid, citric acid, trimellitic acid, pyromellitic acid, pentaerythritol, and trimethylolpropane.

As the polycaprolactone resin which is a polyhydroxyalkanoate resin, a resin obtained by ring-opening polymerization at room temperature using ε-caprolactone using active hydrogen such as alcohol as an initiator can be used. . The initiator preferably has two or three functional groups. The number average molecular weight of the polycaprolactone ranges from 5,000 to 200,000, preferably from 10,000 to 100,000. When the number average molecular weight is less than 5,000, practical physical properties as a sheet cannot be obtained, which is not preferable. On the other hand, production of polycaprolactone having a number average molecular weight exceeding 200,000 is difficult and impractical.

In addition, a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate can be added to the polylactic acid resin. This includes, for example, resins produced by microorganisms such as hydrogen bacteria (Alculigens eutrophus). The number average molecular weight of this resin is 5
In the range of 0.00-1,000,000, preferably 7
It is between 000 and 90,000. When the number average molecular weight is less than 50,000, practical physical properties as a sheet are hardly exhibited, and on the other hand, it is difficult to produce a resin exceeding 1,000,000. The weight ratio of 3-hydroxyvalerate is preferably in the range of 5 to 25 mol%.
Further, a long-chain hydroxyalkanoate may be copolymerized. The amount of the resin added is less than 100 parts by weight based on 100 parts by weight of the polylactic acid-based resin. When this addition amount is 10
If the amount is more than 0 parts by weight, the characteristics of the polylactic acid-based resin are lost, which is not preferable.

The filler added as necessary to the resin composition used in the present invention may be either an inorganic filler or an organic filler. Examples of the inorganic filler include oxides such as calcium oxide, magnesium oxide, barium oxide, aluminum oxide, boron oxide, titanium oxide, zirconium oxide, tin oxide, antimony oxide, heavy calcium carbonate, light calcium carbonate, and magnesium carbonate. ,
Carbonates such as barium carbonate, hydroxides such as magnesium hydroxide and calcium hydroxide, sulfates such as barium sulfate and aluminum sulfate, silicates such as hydrous aluminum silicate and hydrous magnesium silicate, Ketjen Black EC,
Examples include conductive fillers such as furnace black and acetylene black.

Examples of the organic filler include cereals such as wheat, corn, and rice; potato starch such as potato, sweet potato, and tapioca; and polysaccharides such as cellulose, chitin, and chitosan. These may be used alone or in combination of two or more, and may be used in combination of an inorganic filler and an organic filler.

These fillers are used for the purpose of improving the agglomeration of the particles and the affinity with the polylactic acid resin, for example, γ-glycidoxypropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane. Silane coupling agents such as methoxysilane, and titanate-based cups such as tetraoctyl-bis (ditridecylphosphite) titanate and tetra (2,2-diallyloxymethyl-1-butyl) -bis (di-tridecyl) phosphite titanate Ring agent, aluminate-based coupling agent such as acetoalkoxyaluminum diisopropylate, acetylene alcohol such as 3,5-dimethyl-1-hexyl-3-ol, 3,6-dimethyl-4-octyne-3,6- Diol, 2,4,7,9-tetramethyl-5-decyne-
4,7-diol, 2,4,7,9-tetramethyl-5
The surface may be modified by using a dry method, a wet method or an integral blend method using acetylene glycol such as -decine-4,7-diol (polyoxyethylene) ether.

The average particle diameter of the inorganic filler used in the present invention is in the range of 0.01 to 10 μm, preferably 0.05 to 10 μm.
5 μm. When the average particle size is less than 0.01 μm,
The dispersion of the filler in the polylactic acid resin is poor,
If it exceeds m, the toughness of the polylactic acid-based resin sheet may be reduced. The average particle size of the organic filler is 1 to 60 μm.
m, preferably 20 to 40 μm. If the average particle size is less than 1 μm, it is difficult to produce an organic filler, and if it exceeds 60 μm, the toughness of the sheet may be reduced, which is not preferable. The amount of these fillers to be added is 50 parts by weight or less, preferably 30 parts by weight or less based on 100 parts by weight of the polylactic acid-based resin. If the amount exceeds 50 parts by weight, the flexibility of the polylactic acid-based resin sheet is lost, and secondary processing such as vacuum forming, pressure forming or press forming becomes difficult.

Further, if necessary, pentaerythrityl-tetrakis [3] may be added to the polylactic acid-based resin sheet of the present invention.
-(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 3,9-bis [2- [3- (3
-T-butyl-4-hydroxy-5-methylphenyl)
-Propionyloxy] -1-dimethyl] -2,4.
Phenolic antioxidants such as 8,10-tetraoxaspiro [5,5] undecane, tris (2,6-di-butylphenyl) phosphite, cyclic neopentanetetrayl-bis (2,6-di- Phosphorus-based antioxidants such as butyl-4-methylphenyl) phosphite, surfactants such as glycerin fatty acid ester, polyglycerin fatty acid ester, di-2-ethylhexyl azelate, various pigments, various ultraviolet inhibitors and other additives. Agents can also be added.

When the polylactic acid-based resin composition is molded, the water content of the polylactic acid-based resin and the resin composition is 2.
0% or less, preferably 1.5% or less, more preferably 1.0% or less. When the water content exceeds 2.0%, the ester bond in the polylactic acid-based resin is decomposed by hydrolysis during melt-kneading, and the strength of the obtained polylactic acid-based resin sheet is reduced. Not preferred.

The polylactic acid-based resin sheet has a water content of 2.0
%, A polylactic acid-based resin, a silicone oil and a lubricant adjusted to not more than 10% are melt-kneaded in a pressure kneader, and then immediately melt-kneaded again with a mixing roll to produce a sheet-like molded product. This sheet-like molded product is pulverized with a pelletizer to obtain a pellet-shaped molded product (hereinafter, simply referred to as a pellet). Next, after adjusting the moisture content of the pellets to 2.0% or less, the pellets are melt-kneaded by an extruder and formed into a sheet by a calendering machine. The thickness of the polylactic acid-based resin sheet is usually 100 to 1,000 μm, preferably 300 to 1,000 μm.
It is selected within the range of 700 μm. When the thickness of the polylactic acid-based resin sheet is less than 100 μm or more than 1,000 μm, the rigidity of the molded product and the reproducibility of the mold after secondary molding such as vacuum molding, pressure molding and press molding are preferable. Absent.

[0027]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Each component shown in Table 1 (Examples 1 to 6) and Table 2 (Comparative Examples 1 to 6) comprising a polylactic acid-based resin, a polyalkylalkanoate-based resin, an inorganic filler, a silicone oil and a lubricant was heated to 180 ° C. After melt-kneading with a heated pressure kneader for 20 minutes, the mixture was immediately melt-kneaded with a mixing roll heated to 180 ° C. for 5 minutes to produce a sheet-like molded product. This sheet-like molded product is heated at room temperature for 7
After cooling to 0 ° C. or less, the mixture was pulverized using a pelletizer to form pellets. The pellets are heated at a cylinder temperature of 1
The mixture is fed to an extruder heated to 85 ° C., melt-kneaded, and then rolled at a roll temperature of 20 using a calendering machine.
0.3mm or 0.5mm thick, 800m wide at 0 ° C
m of the polylactic acid-based resin sheet was molded and evaluated by the following methods, and the results are shown in Tables 1 and 2.

The details of each component are as follows. <Polylactic acid-based resin> Polylactic acid: Lacty 1012 [manufactured by Shimadzu Corporation, trade name] <Polyalkyl alkanoate-based resin> Polybutylene succinate: Bionole 1001 [manufactured by Showa Polymer Co., Ltd.] <inorganic filler> Heavy calcium carbonate: Whiten S. B (average particle size 1.
4 μm) [trade name, manufactured by Shiraishi Calcium Co., Ltd.] <Silicone oil> Methylstyryl-modified silicone: KF-410 [trade name, manufactured by Shin-Etsu Chemical Co., Ltd.] Viscosity (Ostwald method; 25 ° C.) 888 cSt <Lubricant> Behenic acid: EXL 5 [Product name, manufactured by Asahi Denka Kogyo Co., Ltd.]

Further, the evaluation method of each evaluation item in Tables 1 and 2 is as follows. (1) Moisture content of polylactic acid-based resin, and composition composed of polylactic acid-based resin, silicone, and lubricant: Gravimetric titration-type water measuring device: temperature measured using Mitsubishi CA-06 type (manufactured by Mitsubishi Chemical Corporation, trade name). It was measured at 200 ° C. by the N ₂ purge method.

(2) Roll Peeling Property The peeling property of the sheet from the calender roll and the peeling stability for long-run production were evaluated as follows. ：: Easy peeling and stable for long run production. X: The peelability is poor, and stable production is difficult.

(3) Bleed test The polylactic acid-based resin sheet was left in an oven heated to 70 ° C., and the appearance change of the sheet after 24 hours was visually observed. ：: No bleed. X: There is bleed.

(4) Biodegradability of polylactic acid-based resin sheet A polylactic acid-based resin sheet is buried at a depth of 20 cm in soil, left for 6 months from April to September, taken out, and changed in appearance. Was visually observed, and evaluated as follows with o and x. ：: Appearance change was observed. X: No change in appearance was observed.

[0033]

[Table 1]

[0034]

[Table 2]

As a result of the evaluation, as shown in Table 1, the composition obtained by adding the silicone oil and the lubricant to the polylactic acid resin exhibited excellent calender roll releasability and no bleeding phenomenon was observed. Was. Further, a polymer alloy of a polylactic acid-based resin and polybutylene succinate and a composite material obtained by adding a filler (heavy calcium carbonate) to the polymer alloy are similarly prepared by adding a silicone oil and a lubricant to the sheet by a calender molding method. Molding was possible.
No bleeding phenomenon was observed in these sheets.

In Comparative Example 1 in which the silicone oil and the lubricant were not added, and in Comparative Examples 2 and 3 in which the silicone oil and the lubricant were not used, the melt-kneaded product of the polylactic acid-based resin was not peeled off from the roll. The polylactic acid resin sheet could not be formed. Comparative Examples 4 to 6 in which the addition amounts of the silicone oil and the lubricant were larger than the specified amounts
In No., the melt-kneaded product could not be transferred to a roll, and a sheet could not be formed.

Comparative Example 7 The pellets used in Example 3 were placed in a room at a constant temperature and humidity of 60 ° C. and a humidity of 95% RH.
The pellets having a water content of 2.6% obtained by allowing to stand for one day were formed into a sheet at a roll temperature of 200 ° C. using a calendering machine. The obtained sheet did not have the strength to withstand use.

[0038]

According to the present invention, a resin composition obtained by adding silicone and a lubricant to a polylactic acid resin can be formed into a sheet shape with good roll separation by a calendering method. No bleeding phenomenon is observed, and it can be decomposed under natural environment, which is suitable for environmental problems. Since the polylactic acid-based resin sheet of the present invention can be formed by a calender method, it can be produced economically,
Further, sheets for trays for storing, transporting, and storing OA equipment, AV equipment, home appliances, lenses, and the like, or sheets for carrier tape for packaging electronic components,
Since it can be used in various fields such as a magnetic card and a base sheet for an IC card, its industrial utility value is extremely high.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 67/04 C08L 67/04 // (C08L 67/04 83:04) B29K 67:00 B29L 7:00

Claims (2)

[Claims] 1. A polylactic acid-based resin (100 parts by weight)
A resin composition obtained by calender-molding a resin composition obtained by adding and blending silicone and a lubricant in an amount of from 0.05 to 2.95 parts by weight and a total amount of not more than 3.0 parts by weight. Lactic acid based resin sheet. 2. A polylactic acid, wherein the resin composition according to claim 1 is melted and calendered, wherein the polylactic acid-based resin and the resin composition are molded with a water content of 2.0% or less. A method for producing a resin sheet.