JP2006169430A - Thermoformed article and process for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoformed article that is excellent in heat resistance and impact resistance and has biodegradability and to provide a process for producing the thermoformed article. <P>SOLUTION: The thermoformed article is produced by thermoforming a thermoforming sheet formed from a resin composition comprising a biodegradable aromatic/aliphatic polyester resin A having a melting point Tm of 170-240°C and a biodegradable aromatic/aliphatic polyester resin B having a melting point Tm of 100-130°C wherein the initiation temperature of thermal deformation is a temperature exceeding 150°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

   The present invention relates to a thermoformed article having biodegradability and excellent heat resistance and impact resistance, and a method for producing the same.

  Today, convenience stores and supermarkets sell a wide variety of prepared foods such as side dishes and bento boxes. These prepared foods are made of polystyrene resin, polypropylene resin, aromatic polyester resin ( For example, it is provided and sold after being stored in a food container formed by thermoforming a synthetic resin sheet such as polyethylene terephthalate) into a desired shape.

  And the person who purchased the cooked food is often heated using the microwave while the food is stored in the food container because the food is cold in the purchased state. After that, the food container is often used as tableware.

  However, among the food containers described above, particularly when polystyrene is used as a raw material, there is a problem that if the food container is heated with a microwave oven, the food container cannot withstand the heating temperature and deforms. It was.

  If the food container is left uneaten or unsold at the store, the food is discarded as raw garbage, while the food container is washed and collected by the manufacturer. It is carried out. Therefore, there has been a problem that a large amount of labor is required for the operation of separating the food container from the food and the operation of cleaning the dirty food container.

  Furthermore, recycling is being promoted as part of the protection of the global environment, and food left over is decomposed using microorganisms and reused as fertilizer. The above food containers are made of polystyrene resin. Because it is made of synthetic resin that does not have biodegradability, such as polypropylene resin and aromatic polyester resin, it has to be done after separating leftover food from food containers. was there.

  On the other hand, aliphatic polyester-based resins such as polylactic acid-based resins are naturally degradable by microorganisms, that is, biodegradable. Due to its low heat resistance, it has not been widely used.

  Therefore, in Patent Document 1, a biodegradable sheet obtained by pre-crystallizing a sheet made of a resin composition containing a polylactic acid-based resin having a biodegradable product and a polyester having a glass transition temperature and a melting point within a predetermined range. In addition, food containers using this biodegradable sheet have been proposed.

  However, since the heat resistance of the food container obtained using the biodegradable sheet is about 80 ° C., as described above, the food container is deformed or melted when heated using a microwave oven. There was a problem such as.

  Moreover, since the biodegradable sheet is preliminarily crystallized, the elongation at the time of molding is poor and the moldability is inferior, and a food container having a desired shape cannot be obtained satisfactorily.

  Patent Document 2 discloses 20 to 80% by weight of a biodegradable polyester resin having a Tg temperature of 40 to 70 ° C. composed of a semiaromatic polyester unit and an aliphatic polyester unit, a semiaromatic polyester unit and an aliphatic polyester unit. A biodegradable resin composition for molding comprising 40 to 10% by weight of a biodegradable polyester resin having a Tg temperature of −10 to −50 ° C. and 10 to 40% by weight of an inorganic moldability modifier. And the thermoforming method of the sheet | seat which consists of this resin composition is proposed.

  However, the sheet made of the biodegradable resin composition for molding is pre-heated at a temperature lower than the crystallization temperature of the biodegradable polyester resin having a Tg temperature of 40 to 70 ° C. and then thermoformed with a mold at room temperature. Therefore, the crystallization of the polyester resin is insufficient, and the heat resistance of the resulting thermoformed product is about 90 ° C. When the food container is heated using a microwave oven as described above, the food container may be deformed. Or, problems such as melting occurred.

  In recent years, a wide variety of frozen foods that can be stored in a frozen state for a long period of time while being heated, cooked and eaten in a short time using a microwave oven have been sold and used.

  For such frozen foods, a plurality of frozen foods are packed in a transport case while maintaining a frozen state of −20 ° C. or less, particularly around −30 ° C., and then a store such as a convenience store from a manufacturing factory. It is transported using a vehicle. During this transportation, frozen foods are frequently subjected to impacts associated with transportation, and the impact force may damage food containers. To prevent such damage, food products used for frozen foods Containers are required to have impact resistance at low temperatures.

In addition, when taking frozen food from the store to the home, the temperature rises due to contact with the outside air, and impact resistance at this temperature is also required, and a wide temperature range from the low temperature in the frozen state to the high temperature close to the outside temperature. Impact resistance is required over a range, and frozen foods are also heated and cooked in a short time using a microwave oven from the frozen state as described above, so heat resistance is also required. Therefore, there has been a demand for a food container that has both impact resistance and heat resistance in a wide temperature range from low temperature to high temperature.
JP 2003-147177 A JP 2004-131621 A

  The present invention provides a thermoformed article having excellent heat resistance and impact resistance and biodegradability, and a method for producing the same.

  The thermoformed product of the present invention comprises a biodegradable aromatic aliphatic polyester resin A having a melting point Tm of 170 to 240 ° C. and a biodegradable aromatic aliphatic polyester resin B having a melting point Tm of 100 to 130 ° C. A thermoformed product obtained by thermoforming a thermoforming sheet comprising a resin composition, wherein the heat deformation start temperature is higher than 150 ° C. In the following, the biodegradable aromatic aliphatic polyester resin A may be simply abbreviated as “polyester resin A”, and the biodegradable aromatic aliphatic polyester resin B may be simply abbreviated as “polyester resin B”. is there.

  The biodegradable aromatic aliphatic polyester resin used in the present invention is a copolymer of an aromatic ester and an aliphatic ester, and has an almost intermediate property between the aromatic polyester resin and the aliphatic polyester resin. have.

  The biodegradable aromatic aliphatic polyester resin differs depending on what is used as a component of the aromatic ester and the aliphatic ester, or at what ratio the aromatic acid and the aliphatic acid are mixed. The biodegradable aromatic aliphatic polyester resin having an aromatic acid ratio of 5 to 96 mol% and an aliphatic acid ratio of 4 to 95 mol% is excellent in biodegradability, Practical and preferred.

  Specifically, in such a biodegradable aromatic aliphatic polyester resin, a dicarboxylic acid in which an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid are mixed and a divalent aliphatic alcohol form an ester bond. This is a resin obtained.

  Here, as the divalent aliphatic alcohol constituting the biodegradable aromatic aliphatic polyester resin, for example, ethylene glycol, diethylene glycol, propylene glycol, 2-methyl-1,3-pentanediol, 1,6- Examples include hexanediol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 1,4-butanediol, ethylene glycol, propylene glycol, 1,4- Butanediol is preferred.

  Moreover, the dicarboxylic acid which comprises a biodegradable aromatic aliphatic polyester-type resin contains both aromatic dicarboxylic acid and aliphatic dicarboxylic acid. Examples of such aromatic dicarboxylic acids include 1,4-terephthalic acid, 1,3-terephthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and ester-forming derivatives thereof. 1,4-terephthalic acid and 1,3-terephthalic acid are preferable.

  Furthermore, examples of the aliphatic dicarboxylic acid include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, fumaric acid, 2,2-dimethylglutaric acid, suberic acid, 1,3. -Cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, diglycolic acid, itaconic acid, maleic acid, and ester-forming derivatives thereof, such as succinic acid, glutaric acid, adipic acid, pimelic acid, azelain Acid and sebacic acid are preferred.

  And, when the biodegradable aromatic aliphatic polyester resin has a large amount of aromatic dicarboxylic acid, the heat resistance and mechanical strength increase, whereas when the amount of the aliphatic dicarboxylic acid increases, the biodegradability tends to increase. .

  The present invention relates to a biodegradable aromatic aliphatic polyester resin A having a high heat resistance and a melting point Tm of 170 to 240 ° C., and a biodegradable aromatic aliphatic polyester having a high biodegradability and a melting point Tm of 100 to 130 ° C. The resin B is used in combination.

  The dicarboxylic acid constituting the biodegradable aromatic aliphatic polyester resin A having a melting point Tm of 170 to 240 ° C. in the resin composition constituting the thermoforming sheet is 50 to 96 mol% of the aromatic dicarboxylic acid. And what consists of 4-50 mol% of aliphatic dicarboxylic acid is preferable, and 0-7 mol% of sulfonate compounds may be contained.

  As the sulfonate compound, a commonly used sulfonate compound containing an alkali metal or alkaline earth metal salt of a dicarboxylic acid containing a sulfonate group or an ester-forming derivative thereof can be used. An alkali metal salt of sulfoisophthalic acid or a mixture thereof, particularly preferably a sodium salt.

  The biodegradable aromatic aliphatic polyester resin A may contain a filler in advance in order to improve the heat resistance and strength of the thermoformed product. Examples of such fillers include calcium carbonate, magnesium carbonate, calcium hydroxide, calcium oxide, magnesium oxide, aluminum oxide, silicon oxide, iron oxide, boron nitride, titanium oxide, talc, wax stone clay, and silica powder. Powder, calcium carbonate, mica, sericite, bentonite, perlite, zeolite, wollastonite, fluorite, dolomite, quicklime, slaked lime, kaolin, chlorite, diatomaceous earth and the like. By containing an appropriate amount of these fillers, the heat resistance and strength of the thermoformed product can be improved.

  For the biodegradable aromatic aliphatic polyester resin A, a pigment, an antioxidant, an antistatic agent, a matting agent, a coloring agent, an aromatic agent, an anti-degradation agent, a fluorescent brightening agent, and an ultraviolet ray absorbing agent are preliminarily provided as necessary. Auxiliary components such as an agent, an ultraviolet stabilizer, a slip agent, a filler, carbon black, a thickener, a chain extender, a crosslinking agent, a plasticizer, a stabilizer, a viscosity stabilizer, and a flame retardant may be contained.

  The biodegradable aromatic aliphatic polyester resin A having a melting point Tm of 170 to 240 ° C. is commercially available, for example, from DuPont under the trade name “Biomax”, and in particular, the trade name “Biomax WA100F”. What is marketed by "is used suitably. This “Biomax WA100F” includes a filler and auxiliary components as described above.

  And when melting | fusing point Tm of the said biodegradable aromatic aliphatic polyester-type resin A is low, while the heat resistance of a thermoformed product will fall, when high, the biodegradability of a thermoformed product will fall, 170- It is limited to 240 ° C. and is preferably 180 to 220 ° C.

  Furthermore, if the glass transition temperature Tg of the biodegradable aromatic aliphatic polyester-based resin A is low, the heat resistance of the thermoformed product may be lowered. Since the biodegradability of the product by microorganisms may be lowered, 20 to 70 ° C. is preferable.

  The dicarboxylic acid constituting the biodegradable aromatic aliphatic polyester resin B having a melting point Tm of 100 to 130 ° C. in the resin composition constituting the thermoforming sheet is 5 to 65 aromatic dicarboxylic acid. What consists of 35-95 mol% of aliphatic dicarboxylic acid is preferable, and 0-7 mol% of sulfonate compounds may be contained.

  As the sulfonate compound, a commonly used sulfonate compound containing an alkali metal or alkaline earth metal salt of a dicarboxylic acid containing a sulfonate group or an ester-forming derivative thereof can be used. An alkali metal salt of sulfoisophthalic acid or a mixture thereof, particularly preferably a sodium salt.

  The biodegradable aromatic aliphatic polyester resin B may contain a filler in advance in order to improve the heat resistance and strength of the thermoformed product. Examples of such fillers include calcium carbonate, magnesium carbonate, calcium hydroxide, calcium oxide, magnesium oxide, aluminum oxide, silicon oxide, iron oxide, boron nitride, titanium oxide, talc, wax stone clay, and silica powder. Powder, calcium carbonate, mica, sericite, bentonite, perlite, zeolite, wollastonite, fluorite, dolomite, quicklime, slaked lime, kaolin, chlorite, diatomaceous earth and the like. By containing an appropriate amount of these fillers, the heat resistance and strength of the thermoformed product can be improved.

  For the biodegradable aromatic aliphatic polyester resin B, pigments, antioxidants, antistatic agents, matting agents, coloring agents, fragrances, deterioration inhibitors, fluorescent whitening agents, ultraviolet absorptions are preliminarily provided as necessary. Auxiliary components such as an agent, an ultraviolet stabilizer, a slip agent, a filler, carbon black, a thickener, a chain extender, a crosslinking agent, a plasticizer, a stabilizer, a viscosity stabilizer, and a flame retardant may be contained.

  Examples of the biodegradable aromatic aliphatic polyester resin B having a melting point Tm of 100 to 130 ° C. include, for example, the product name “Ecoflex” from BASF and the product name “Easter Bio / Easter BIO” from Eastman Chemical. In particular, commercially available products under the trade name “ENPOL / ENPOL” from Ile Chemical Co., in particular under the trade name “ECOFLEX F BX7011” from BASF Corp. are preferably used.

  And when melting | fusing point Tm of the said biodegradable aromatic aliphatic polyester-type resin B is low, while the heat resistance of a thermoformed product falls or the releasability from the shaping | molding die of a thermoformed product falls, it is high. And since the biodegradability and impact resistance of a thermoformed product fall, it is limited to 100-130 degreeC, and 105-125 degreeC is preferable.

  Furthermore, if the glass transition temperature Tg of the biodegradable aromatic aliphatic polyester resin B is high, the impact resistance of the thermoformed product may be lowered. Since the heat resistance of the molded product and the releasability from the mold may be lowered, −10 to −50 ° C. is more preferable.

  In the present invention, the glass transition point Tg and melting point Tm of the biodegradable aromatic aliphatic polyester resin are those measured in the following manner. Using a differential scanning calorimeter device, 10 to 20 mg of a sample is filled in a measurement container, and the sample is heated at a rate of 10 ° C./min from the end of the melting peak of the resin with a nitrogen gas flow rate of 30 ml / min. Heat and melt to 30 ° C higher temperature and hold at that temperature for 10 minutes, then cool the sample at a rate of 10 ° C / min to at least about 50 ° C below the glass transition temperature of the resin. Again, the sample was heated to a temperature 20-30 ° C. higher than that at the end of the melting peak of the resin at a rate of temperature increase of 10 ° C./min, and the glass transition temperature was measured. Extrapolated glass transition specified in JIS K7121: 1987 was started. While the temperature was the glass transition temperature Tg, the peak top temperature specified in JIS K7121: 1987 was the melting point Tm. As the differential scanning calorimeter, the T.C. A. What is marketed with the brand name "DSC2010" from Instruments can be used.

  If the content of the biodegradable aromatic aliphatic polyester resin A in the resin composition is small, the heat resistance of the thermoformed product may be lowered. May fall, 50 to 95 weight% is preferable and 75 to 90 weight% is more preferable. For the same reason, the content of the biodegradable aromatic aliphatic polyester resin B in the resin composition is preferably 5 to 50% by weight, and more preferably 10 to 25% by weight.

  Furthermore, the resin composition may contain a polylactic acid resin within a range that does not impair the heat resistance of the thermoformed product. This polylactic acid resin is a resin obtained by polymerizing or copolymerizing naturally occurring lactic acid. Lactic acid rarely means β-hydroxypropionic acid, but usually refers to α-hydroxypropionic acid, and this α-hydroxypropionic acid has an asymmetric carbon atom in the molecule. Are optically active, and there are three types of racemates: D-form, L-form, and D-form and L-form mixed in equal amounts.

  Therefore, polylactic acid obtained by polymerizing lactic acid can have various properties by adjusting the mixing ratio and polymerization method of the above three types of lactic acid. There are a wide variety from crystalline to amorphous, and the melting point or softening point varies.

  As the polylactic acid resin, L-lactic acid and / or D-lactic acid is polymerized, or one or two or more lactides selected from the group consisting of L-lactide, D-lactide and DL-lactide are used. In addition to polylactic acid obtained by ring-opening polymerization (see “Chemical Formula 1” below), a copolymer of L-lactic acid and / or D-lactic acid and hydroxycarboxylic acid can be used.

  When producing a polylactic acid-based resin, when L-lactic acid or D-lactic acid alone is used as a monomer, or L-lactic acid and D-lactic acid are used in combination as monomers without containing a copolymer component such as hydroxycarboxylic acid In this case, when either L-lactic acid or D-lactic acid is used in a large amount compared to the other, the resulting polylactic acid resin becomes crystalline, while L-lactic acid and D-lactic acid are used as monomers. When used in substantially the same amount, the resulting polylactic acid resin is non-crystalline, but from the viewpoint of excellent heat resistance and mechanical strength, in the present invention, a crystalline polylactic acid resin is used. It is preferable to use it.

  Examples of the hydroxycarboxylic acid include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, and 6-hydroxycaproic acid.

  Also, if the content of the polylactic acid resin in the resin composition is small, the effect of blending the polylactic acid resin may not be manifested, whereas if it is large, the heat resistance of the thermoformed product may be reduced. Therefore, with respect to 100 parts by weight of the total amount of the biodegradable aromatic aliphatic polyester resin A having a melting point Tm of 170 to 240 ° C. and the biodegradable aromatic aliphatic polyester resin B having a melting point Tm of 100 to 130 ° C. 50 parts by weight or less is preferable, 30 parts by weight or less is more preferable, and 5 to 30 parts by weight is particularly preferable.

  The resin composition is a resin composition containing two types of biodegradable aromatic aliphatic polyester resins A and B having the predetermined melting point, and may contain a polylactic acid resin. This is as described above. The biodegradable aromatic aliphatic polyester resin and polylactic acid resin are also as described above.

  Further, the resin composition may contain a small amount of a resin other than the polyester resins A and B and the polylactic acid resin as long as the heat resistance of the thermoformed product is not impaired. Examples of such resins include aromatic polyester resins, aliphatic polyester resins, polyolefin resins, and polystyrene resins.

  Further, the resin composition may further contain a filler as necessary within a range not impairing the effects of the present invention. Examples of the filler include calcium carbonate, magnesium carbonate, calcium hydroxide, calcium oxide, magnesium oxide, aluminum oxide, silicon oxide, iron oxide, boron nitride, titanium oxide, talc, wax stone clay, and silica powder. Calcium carbonate, mica, sericite, bentonite, perlite, zeolite, wollastonite, fluorite, dolomite, quicklime, slaked lime, kaolin, chlorite, diatomaceous earth and the like. By containing an appropriate amount of these fillers, the heat resistance and strength of the thermoformed product can be improved.

  In the resin composition, if necessary, pigments, antioxidants, antistatic agents, matting agents, coloring agents, fragrances, deterioration inhibitors, fluorescent brighteners, ultraviolet absorbers, ultraviolet stabilizers, slips You may contain auxiliary components, such as an agent, a filler, carbon black, a thickener, a chain extender, a crosslinking agent, a plasticizer, a stabilizer, a viscosity stabilizer, a flame retardant.

  The method of adding a resin other than the polyester resins A and B, a filler, and an auxiliary component to the resin composition containing the polyester resins A and B is not particularly limited, and the polyester resins A and B are mixed. It may be added later, or may be added in advance to the biodegradable aromatic aliphatic polyester resin A or the biodegradable aromatic aliphatic polyester resin B.

  The thermoformed article of the present invention is obtained by thermoforming a thermoforming sheet comprising a resin composition containing two types of biodegradable aromatic aliphatic polyester resins A and B having the predetermined melting point Tm. As a thermoforming method, a general-purpose method can be conventionally used as a sheet forming method. For example, plug-assist molding, plug ring molding, back pressure molding such as air cushion molding, direct vacuum molding, etc. , Drape molding, plug assist molding, snapback molding, plug ring molding, air slip ring molding and other vacuum molding, pressure molding, press molding and other molding methods.

  In thermoforming the above thermoforming sheet, it is preferable to heat soften the thermoforming sheet, and to improve the thermoformability of the thermoforming sheet by heat softening the thermoforming sheet in advance. Can be made.

  Furthermore, it is preferable that the thermoforming sheet is heat-softened and then brought into contact with the shaping surface of the mold to be thermoformed. In addition, even if a shaping | molding die is a shaping | molding die with a flat shaping surface, it may consist of either a female type | mold or a male type | mold, and may consist of a female type | mold and a male type | mold.

  In addition, the heat-softened thermoforming sheet is squeezed along the shaping surface of either the female mold or the male mold, or both, and brought into contact with the shaping surface of either the female mold or the male mold. It is preferable to perform thermoforming.

  In this way, the thermoforming sheet is heat-softened after being heat-softened, or the thermoforming sheet is squeezed along the shaping surface of either the female mold or the male mold, or thermoformed. As a result, the thermoformed product has further excellent heat resistance and impact resistance.

  Furthermore, if the heat deformation start temperature of the thermoformed product is low, the thermoformed product may be deformed when the thermoformed product is heated using a microwave oven, so the temperature is limited to a temperature exceeding 150 ° C. or more. A temperature exceeding 200 ° C. is preferred.

  Here, the heat deformation start temperature of the thermoformed product refers to that measured in the following manner. The thermoformed product is manufactured by thermoforming a thermoforming sheet, but when the thermoforming product is subjected to the following heat treatment, the most narrowed part when thermoforming the thermoforming sheet is This is the lowest temperature at which deformation occurs when the dimensional change rate exceeds 5%.

In the heat treatment, first, the squeezed dimension L ₀ of the portion most deeply squeezed during thermoforming of the thermoforming sheet is measured. Next, the set temperature is set to 60 ° C., and the thermoformed product is supplied into a thermostat bath that is held. After 10 minutes have passed since the thermostat bath is held at 60 ° C., the thermoformed product is removed from the thermostat bath. Take out.

Subsequently, after the thermoformed product is allowed to stand in an atmosphere of 23 ° C. and the thermoformed product is sufficiently cooled, the dimension L ₁ after heating in the portion where the squeezing dimension L ₀ is measured is measured, The dimensional change rate is calculated based on
Dimensional change rate (%) = 100 × (L ₀ −L ₁ ) / L ₀

  Further, after changing the set temperature in the thermostat from 60 ° C. to 220 ° C. every 5 ° C., the above procedure was repeated for each set temperature, and the dimensional change rate was calculated for each set temperature. A new thermoformed product is used every time the set temperature in the thermostat is changed. And among the set temperature in a thermostat when the said dimensional change rate exceeds 5%, let minimum temperature be heating deformation start temperature.

  For example, when the thermoformed product is a container including a bottom surface portion and a peripheral wall portion extending upward from the outer peripheral edge of the bottom surface portion, the thermoformed product is most narrowed down when the thermoforming sheet is thermoformed. The squeezed dimension of the portion refers to the maximum height in the vertical direction from the upper surface of the bottom surface to the upper edge of the peripheral wall.

  Next, the manufacturing method of the said thermoformed product is demonstrated. First, a resin composition containing the biodegradable aromatic aliphatic polyester resin A and the biodegradable aromatic aliphatic polyester resin B is molded into a thermoforming sheet using a general-purpose method. Examples of the method for forming the resin composition into a thermoformed sheet include a method of producing a thermoforming sheet by supplying the resin composition to an extruder, melt-kneading, and extruding from a T-die.

And until the temperature T ₁ at the end of the preheating of the thermoforming sheet reaches a temperature satisfying the formula 1, preferably the temperature T ₁ at the end of the preheating reaches a temperature satisfying the formula 3, more preferably the preheating. Preheating and softening are performed until the temperature T ₁ at the end of heating reaches a temperature satisfying Equation 4. The time for preheating the thermoforming sheet (preheating time) refers to the time from the start to the end of preheating of the thermoforming sheet, and the temperature of the thermoforming sheet is the heat. The surface temperature of the molding sheet.
Glass transition temperature Tg + 30 ° C. of biodegradable aromatic aliphatic polyester resin A
≦ T ₁ ≦ Melting point of biodegradable aromatic aliphatic polyester resin A Tm−10 ° C. Formula 1
Glass transition temperature Tg + 35 ° C. of biodegradable aromatic aliphatic polyester resin A
≦ T ₁ ≦ Melting point of biodegradable aromatic aliphatic polyester resin A Tm−60 ° C. Formula 3
Glass transition temperature Tg + 65 ° C. of biodegradable aromatic aliphatic polyester resin A
≦ T ₁ ≦ Melting point of biodegradable aromatic aliphatic polyester resin A Tm−70 ° C. Formula 4

  This is because the temperature of the thermoforming sheet at the end of the preheating does not reach 30 ° C. higher than the glass transition temperature Tg of the biodegradable aromatic aliphatic polyester resin A. This is because when the heating is completed, the moldability is deteriorated due to insufficient softening of the thermoforming sheet.

  On the other hand, when the temperature of the thermoforming sheet at the end of preheating exceeds 10 ° C. lower than the melting point Tm of the biodegradable aromatic aliphatic polyester resin A, the thermoforming sheet is excessively softened, As a result, a drawdown occurs and the thermoformability of the thermoforming sheet decreases, or the thermoforming sheet cannot withstand stretching during thermoforming, and the thickness of the thermoformed product becomes uneven or This is because tearing occurs in the thermoformed product.

The temperature of the sheet for thermoforming during the preheating, it is sufficient temperature T ₁ of the sheet for thermoforming at preheating end satisfies Expression 1, may optionally repeatedly rising and falling but, thermoforming Since it is difficult to adjust the crystallization of the resin composition constituting the sheet for heat treatment, the heat resistance and impact resistance of the resulting thermoformed product may be lowered. It is preferable to heat and adjust so as to rise or to arbitrarily repeat the rise and the equilibrium at the same temperature.

Next, the thermoforming sheet preheated and softened as described above is brought into contact with a mold heated and held at a temperature T ₂ satisfying Equation ₂ , preferably at a temperature T ₂ satisfying Equation 5. A thermoformed product can be obtained by thermoforming. At this time, the preheated and softened thermoforming sheet is preferably kept at the heating temperature at the end of the preheating until it is brought into contact with the mold and thermoforming is started. In addition, the temperature of a shaping | molding die means the surface temperature of the part which the sheet | seat part for thermoforming which forms a thermoformed product contacts, ie, the surface temperature of the shaping surface of a shaping | molding die.
Glass transition temperature Tg + 40 ° C. of biodegradable aromatic aliphatic polyester resin A
≦ T ₂ ≦ Melting Point Tm of Biodegradable Aromatic Aliphatic Polyester Resin A Formula 2
Glass transition temperature Tg + 55 ° C. of biodegradable aromatic aliphatic polyester resin A
≦ T ₂ ≦ Melting point of biodegradable aromatic aliphatic polyester resin A Tm−40 ° C. Formula 5

  When the temperature at the time of thermoforming the mold used for thermoforming the thermoforming sheet is less than 40 ° C. higher than the glass transition temperature Tg of the biodegradable aromatic aliphatic polyester resin A, This is because the resin composition constituting the molding sheet is insufficiently crystallized and the heat resistance of the thermoformed product is lowered.

  On the other hand, when the temperature during thermoforming of the mold used for thermoforming the thermoforming sheet exceeds the melting point Tm of the biodegradable aromatic aliphatic polyester resin A, the thermoforming sheet is melted. Because it ends up.

  The thermoforming sheet is thermoformed by bringing it into contact with a mold that is heated and held in the above-mentioned temperature range. The time for thermoforming the thermoforming sheet by contacting the mold (thermoforming time). Is short, the resin composition constituting the thermoforming sheet is insufficiently crystallized and the heat resistance of the thermoformed product is reduced, so it is limited to 1.5 seconds or more, and if too long, Since crystallization of the resin proceeds excessively and the impact resistance of the thermoformed product may be lowered, 3 to 10 seconds is preferable, and 3 to 6 seconds is more preferable.

  Here, the time for thermoforming the thermoforming sheet in contact with the forming die (thermoforming time) is the first time that the thermoforming sheet portion forming the thermoformed product is on the forming die (the shaping surface of the forming die). It means the time required from the contact until the thermoforming of the thermoforming sheet is completed and the thermoformed product is released from the mold.

  The thermoformed product thus obtained has a wide range of temperatures from low to high, since the biodegradable aromatic aliphatic polyester resin constituting it is crystallized with an appropriate degree of crystallinity. It has excellent impact resistance over a range and also has excellent heat resistance.

  The thermoformed product of the present invention comprises a biodegradable aromatic aliphatic polyester resin A having a melting point Tm of 170 to 240 ° C. and a biodegradable aromatic aliphatic polyester resin B having a melting point Tm of 100 to 130 ° C. It is a thermoformed product obtained by thermoforming a thermoforming sheet comprising a resin composition, and has a biodegradability because the heat deformation starting temperature is a temperature exceeding 150 ° C. It can be decomposed by microorganisms and is excellent in terms of protecting the global environment.

  Furthermore, the thermoformed product of the present invention has excellent heat resistance, can be heated without being deformed using a microwave oven, and has excellent impact resistance over a wide range from low temperature to high temperature. , Can be developed for various uses. And when the thermoformed product of this invention is shape | molded in the container, it can use suitably as a container for accommodating various articles | goods.

  And when this thermoformed product is used as a food container, it can be easily cooked using a microwave oven as described above, and after use, food left over in the food container can be removed. Without separation, the food can be decomposed with microorganisms. And since the said thermoformed goods are excellent in the impact resistance in low temperature especially, it can be used suitably also as a food container for frozen foods.

  Furthermore, in the above thermoformed product, when the heat deformation start temperature is higher than 200 ° C., it has heat resistance capable of withstanding heating by an oven in addition to heating by a microwave oven. Can be used in a wide range of applications.

  And in the said thermoformed article, when a resin composition consists of 50 to 95 weight% of biodegradable aromatic aliphatic polyester-type resin A and 5 to 50 weight% of biodegradable aromatic aliphatic polyester-type resin B The thermoformed product has better heat resistance.

  In addition, in the above thermoformed product, when the polylactic acid resin is contained in an amount of 50 parts by weight or less with respect to 100 parts by weight of the total amount of the polyester resin A and the polyester resin B, the thermoformed product has further excellent biodegradability. Have.

And the manufacturing method of the thermoformed product of this invention is the biodegradable aromatic aliphatic polyester-type resin A whose melting | fusing point Tm is 170-240 degreeC, and biodegradable aromatic aliphatic polyester whose melting | fusing point Tm is 100-130 degreeC. The thermoforming sheet comprising the resin composition containing the resin B is preheated and softened until the temperature T ₁ at the end of the preheating reaches a temperature satisfying the above formula 1, and then the preheated thermoforming is performed. The sheet for heating is heated to a temperature T ₂ satisfying the above-mentioned formula 2 and is thermoformed by contacting with a holding mold for 1.5 seconds or more. First, the sheet for thermoforming is brought to a predetermined temperature. Preheating and softening so as not to impair the formability of the thermoforming sheet, so that in the subsequent thermoforming of the thermoforming sheet using the mold, the thermoforming sheet can be easily and accurately Thermoforming the desired shape Shapes can be easily obtained. The obtained thermoformed article has excellent heat resistance as described above and excellent impact resistance in a wide temperature range from low temperature to high temperature, and can be developed for various applications.

  Further, in the method for producing a thermoformed article, the resin composition is 50 to 95% by weight, more preferably 75 to 90% by weight of the biodegradable aromatic aliphatic polyester resin A, and the biodegradable aromatic aliphatic polyester. When the resin B is composed of 5 to 50% by weight, more preferably 10 to 25% by weight, the obtained thermoformed product has further excellent heat resistance.

Further, in the manufacturing method of the heat molded article, when the temperature T ₁ of the time of preheating ends thermoforming sheet is preheated to a temperature satisfying the above equation 3, the heat molded product obtained is further Excellent impact resistance, especially impact resistance at low temperatures.

Then, in the above-described method for manufacturing thermoformed articles, if the temperature T ₁ of the time of preheating ends thermoforming sheet is preheated so as to satisfy the above equation 4, the molding of the sheet for thermoforming after preheating The thermoforming sheet can be more accurately and easily thermoformed into a desired shape using a mold.

Further, in the method for producing a thermoformed product, when the temperature T ₂ of the mold is heated and maintained at a temperature satisfying the above formula 5, the obtained thermoformed product has further excellent heat resistance and impact resistance. Have.

  And in the manufacturing method of the said thermoforming goods, when making a thermoforming sheet | seat contact a shaping | molding die for 3 to 10 second, thermoforming the thermoforming sheet | seat more accurately, and the thermoforming article which has a desired shape is obtained. In addition, when the thermoforming sheet is brought into contact with the mold for 3 to 6 seconds, the resulting thermoformed product is more accurately molded and has excellent impact resistance. .

  Moreover, in the manufacturing method of the said thermoforming goods, when the resin composition contained 50 weight part or less of polylactic acid-type resin with respect to 100 weight part of total amounts of the polyester-type resin A and the polyester-type resin B, it was more excellent. A thermoformed product having biodegradability can be obtained.

(Examples 1-18, Comparative Examples 1-9)
Biodegradable aromatic aliphatic polyester resin A (trade name “Biomax WA100F” manufactured by DuPont) and biodegradable aromatic aliphatic polyester resin B (trade name “Ecoflex / manufactured by BASF Japan Ltd.”) Ecoflex F BX7011) and 100 parts by weight of a polyester resin having a blending ratio shown in Tables 1 to 3, and a predetermined amount of polylactic acid shown in Tables 1 to 3 (trade name “Lacia H, manufactured by Mitsui Chemicals, Inc.). -440 ") was supplied to a stirrer and mixed uniformly to prepare a forming raw material.

  Then, the raw material for molding is supplied to a single screw extruder, melted and kneaded, extruded from a T die attached to the tip of the extruder, and the extruded sheet is cast on a rotary cooling roll maintained at 20 ° C. While cooling and solidifying, a substantially unstretched thermoforming sheet having a thickness of 400 μm was obtained. In addition, while adjusting the barrel temperature of an extruder so that it might become high sequentially in an extrusion direction in the temperature range of 200-220 degreeC, the temperature of T-die was hold | maintained at 215 degreeC.

  Next, the thermoforming sheet is attached to a transfer clamp base and supplied to the heating zone, and the temperature shown in Table 1 is adjusted while adjusting the temperature of the thermoforming sheet from beginning to end (in the table, “preliminary heating”). Pre-heated and softened for a period of time). In addition, the temperature of the sheet | seat for thermoforming at the time of completion | finish of preheating (it represented with "preheating temperature" in the table | surface) was shown to Tables 1-3.

  Subsequently, the pre-heated and softened thermoforming sheet is immediately put on the female mold so that the temperature does not decrease, and the inside of the female mold is decompressed, so that the thermoforming sheet and the female mold face each other. The space between the surfaces is depressurized to a vacuum state, and the thermoforming sheet is squeezed into the female mold, closely attached to the shaping surface of the female mold and thermoformed (direct vacuum forming), and then released, and the Thomson blade Trimming was performed to obtain a dish-shaped thermoformed product C. The time required from the time when the thermoforming sheet first contacts the shaping surface of the female mold until the thermoformed product is released from the female mold, that is, the “thermoforming time” is shown in the table. Further, during the direct vacuum forming, the shaping surface of the female mold was kept at the “mold temperature” shown in Table 1 throughout.

  As shown in FIG. 1, the dish-shaped thermoformed product C is slanted upward from the entire periphery of the outer peripheral edge of the bottom surface portion of a substantially horizontally long rectangular shape of 88 mm in length × 118 mm in width. It consists of a peripheral wall portion 2 extending outward and a square frame-shaped flange portion 3 having a width of 8 mm extending horizontally from the entire periphery of the upper end edge of the peripheral wall portion, and an upper end opening edge of the peripheral wall portion Was formed in a substantially horizontally long rectangular shape with a length of 109 mm × width of 139 mm, and the height from the upper surface of the bottom surface portion 1 to the upper edge of the peripheral wall portion was 30 mm.

  The heat resistance, microwave oven heat aptitude, strength, impact resistance, moldability and releasability of the thermoformed product C obtained as described above were measured in the following manner, and the results were shown in Tables 1 to 3. It was shown to. However, in Comparative Examples 2 to 4, 7, a thermoformed product C capable of performing the above evaluation could not be obtained.

(Heat-resistant)
First, as shown in FIG. 2A, the squeezed dimension of the portion most deeply squeezed during thermoforming of the thermoforming sheet, that is, from the upper surface of the bottom surface portion 1 of the thermoformed product C to the upper end of the peripheral wall portion 2. The maximum vertical height H ₀ to the edge was measured. Next, the thermoformed product C is supplied into a constant temperature bath set at a set temperature of 60 ° C., and after 10 minutes have passed since the inside of the thermostat bath is held at 60 ° C., the thermoformed product C is kept at a constant temperature. Removed from tank.

Subsequently, after the thermoformed product C is allowed to stand in an atmosphere of 23 ° C. and the thermoformed product C is sufficiently cooled, the vertical height H ₁ of the portion where the maximum height H ₀ is measured (FIG. 2). (See (b)) was measured, and the dimensional change rate was calculated based on the following formula. Note that the flange portion 3 may be warped in the vertical direction after heating, but is not affected when the height H ₁ is measured (see FIG. 2B).
Dimensional change rate (%) = 100 × (H ₀ −H ₁ ) / H ₀

  Further, after changing the set temperature in the thermostat from 60 ° C. to 220 ° C. every 5 ° C., the above procedure was repeated for each set temperature, and the dimensional change rate was calculated for each set temperature. In addition, whenever the preset temperature in a thermostat was changed, the new thermoformed product C was used.

  And the heat resistance of the thermoformed product C was evaluated based on the following reference | standard, making the minimum temperature into the heat deformation start temperature among the setting temperature in a thermostat when the said dimensional change rate exceeded 5%. In addition, the heating deformation start temperature was described in parentheses in the “heat resistance” column of Tables 1 to 3.

A: Heat deformation start temperature exceeds 200 ° C. ○: Heat deformation start temperature exceeds 150 ° C. and 200 ° C. or less Δ: Heat deformation start temperature exceeds 100 ° C. and 150 ° C. or less X: Heat deformation start temperature 100 ° C. Less than

(Suitability for microwave oven heating)
First, similarly to the measurement of heat resistance, the squeezed dimension of the portion most squeezed during thermoforming of the thermoforming sheet, that is, the vertical from the upper surface of the bottom surface portion 1 of the thermoformed product C to the upper edge of the peripheral wall portion. The maximum height H ₀ in the direction was measured. Next, after putting 100 g of salad oil in the thermoformed product C, the thermoformed product C is put into a 500 W microwave oven, and the heating time is set to 30 seconds, and the thermoformed product C is heated using the microwave oven. The thermoformed product C was taken out of the microwave oven, and the temperature of the salad oil in the thermoformed product C was immediately measured.

Subsequently, the thermoformed product C is allowed to stand in an atmosphere of 23 ° C. and cooled until the salad oil in the thermoformed product C reaches 30 ° C., and then the maximum height is measured in the same manner as when measuring heat resistance. The height H ₁ in the vertical direction of the measured portion was measured, and the dimensional change rate was calculated based on the same formula as that for measuring the heat resistance.

  Further, after changing the heating time from 30 seconds to 600 seconds every 30 seconds, the above procedure was repeated for each heating time, and the dimensional change rate was calculated for each heating time. Each time the heating time was changed, a new thermoformed product C was used.

And the minimum temperature was made into deformation temperature among the temperature of the salad oil when the said dimensional change rate exceeded 5%, and the microwave heating aptitude of the thermoformed product C was evaluated based on the following reference | standard. In addition, the deformation temperature was described in parentheses in the column of “Adjustability for microwave oven heating” in Tables 1 to 3.
Dimensional change rate (%) = 100 × (H ₀ −H ₁ ) / H ₀

◎: Deformation temperature exceeds 200 ° C ○: Deformation temperature exceeds 150 ° C and 200 ° C or less △: Deformation temperature exceeds 100 ° C and 150 ° C or less ×: Deformation temperature is 100 ° C or less

(Strength)
The strength of the thermoformed product C was measured using a Tensilon universal testing machine (trade name “RTC-130A” manufactured by Orientec Co., Ltd.). Specifically, the thermoformed product C is erected in a state where the short side of the upper end opening edge is directed in the vertical direction, and between the center portions of the opposing long side outer peripheral edges in the flange portion 3 of the thermoformed product C. Was sandwiched between the pair of compression jigs 4 and 4 of the universal testing machine (see FIG. 3A). The contact width W between the compression jig 4 and the outer peripheral edge of the flange portion 3 of the thermoformed product C was 15 mm.

  Thereafter, as shown in FIG. 3B, the space between the pair of compression jigs 4 and 4 of the universal testing machine is narrowed by 10 mm, so that the thermoformed product C is shortened on the short side of the flange portion. Compressed in the direction at a compression speed of 400 mm / min. And the compression stress at the time of the maximum compression of the thermoformed product C was measured, and intensity | strength was evaluated based on the following reference | standard. In addition, the compressive stress was described in brackets in the “strength” column of Tables 1 to 3.

○: Compressive stress exceeds 1.47N △: Compressive stress exceeds 0.98N and 1.47N or less ×: Compressive stress is 0.98N or less

(Impact resistance)
120 g of water was put into the thermoformed product C, and left in a freezing room at −20 ° C. for one day or more to freeze the water. On the other hand, as shown in FIG. 4, a polyvinyl chloride inclined plate 6 having a constant thickness formed on both sides of a smooth surface on an iron horizontal plate 5 having a thickness of 20 mm on the upper surface. A test apparatus was prepared in which the upper surface was disposed in an upright state with an angle of 75 ° with respect to the horizontal plate 5.

Thereafter, the thermoformed product C containing ice is placed on the upper surface of the inclined plate 6 so that the opening of the thermoformed product C becomes the inclined plate 6, the long side direction of the bottom surface portion 1 is directed to the falling direction, and the flange portion. 3 was arranged so that the height H ₂ (fall height) of the outer peripheral edge in the dropping direction was 30 cm and held by hand.

  Next, release the hand gently and let the thermoformed product C containing ice fall naturally while sliding on the inclined plate 6, causing the thermoformed product C to collide with the horizontal plate 5. It was visually observed whether or not. The series of measurements was performed in an atmosphere at −20 ° C.

Then, the above procedure is performed for 20 thermoformed products C, and the ratio of the containers in which cracks occur in any of the 20 thermoformed products C (cracking rate) is calculated based on the following formula. The impact resistance was evaluated according to the following criteria. In addition, the crack occurrence rate was described in brackets in the column of “impact resistance” in Tables 1 to 3.
Crack generation rate (%) = 100 × number of cracked containers / 20

A: Crack occurrence rate is 0%
○: Crack generation rate exceeds 0% and 50% or less Δ: Crack generation rate exceeds 50% and less than 100% ×: Crack generation rate is 100%

(Formability)
The thermoformed product C was visually observed, and it was evaluated based on the following criteria whether it was molded according to the female mold.
(Double-circle): The thermoformed product C as a female type | mold was obtained, and a deformation | transformation was not confirmed.
○: Slight deformation was confirmed.
Δ: Deformation was confirmed but within the practical range.
X: Remarkable deformation was confirmed.

(Releasability)
The surface of the thermoformed product C was visually observed, and wrinkles generated when the thermoformed product C was released from the female mold were visually observed and evaluated based on the following criteria. The length of the ridge was measured with a caliper.
A: No wrinkle was generated.
○: One wrinkle having a length of less than 10 mm occurred.
Δ: One wrinkle having a length of 10 mm or more occurred.
X: Two or more wrinkles having a length of 10 mm or more were generated.

It is the plane part and sectional drawing of the thermoformed product C obtained in the Example. It is the schematic cross section which showed the point which measures heat resistance. It is the schematic diagram which showed the point which measures intensity | strength. It is the schematic diagram which showed the point which measures impact resistance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bottom part 2 Perimeter wall part 3 Flange part C Thermoformed product

Claims (18)

Thermoforming comprising a resin composition comprising a biodegradable aromatic aliphatic polyester resin A having a melting point Tm of 170 to 240 ° C. and a biodegradable aromatic aliphatic polyester resin B having a melting point Tm of 100 to 130 ° C. A thermoformed product obtained by thermoforming a sheet for heating, wherein the heat deformation starting temperature exceeds 150 ° C. The thermoformed product according to claim 1, wherein the heat deformation starting temperature is higher than 200 ° C. The resin composition is composed of 50 to 95% by weight of biodegradable aromatic aliphatic polyester resin A and 5 to 50% by weight of biodegradable aromatic aliphatic polyester resin B. Item 3. The thermoformed product according to Item 2. The resin composition contains 50 parts by weight or less of a polylactic acid resin with respect to 100 parts by weight of the total amount of the biodegradable aromatic aliphatic polyester resin A and the biodegradable aromatic aliphatic polyester resin B. The thermoformed product according to any one of claims 1 to 3. The thermoformed product according to any one of claims 1 to 4, wherein the thermoformed product is a container including a bottom surface portion and a peripheral wall portion extending upward from an outer peripheral edge of the bottom surface portion. The thermoformed product according to claim 5, wherein the thermoformed product is a food container. Thermoforming comprising a resin composition comprising a biodegradable aromatic aliphatic polyester resin A having a melting point Tm of 170 to 240 ° C. and a biodegradable aromatic aliphatic polyester resin B having a melting point Tm of 100 to 130 ° C. after the use sheet temperature T ₁ of the time of preheating ends to soften preheated until a temperature satisfying the following equation 1, the preheated thermoformed sheet, the temperature T ₂ satisfying the following formula 2 A method for producing a thermoformed product, comprising: thermoforming by contacting a heated and held mold for 1.5 seconds or more.
Glass transition temperature Tg + 30 ° C. of biodegradable aromatic aliphatic polyester resin A
≦ T ₁ ≦ Melting point of biodegradable aromatic aliphatic polyester resin A Tm−10 ° C. Formula 1
Glass transition temperature Tg + 40 ° C. of biodegradable aromatic aliphatic polyester resin A
≦ T ₂ ≦ Melting Point Tm of Biodegradable Aromatic Aliphatic Polyester Resin A Formula 2 The resin composition comprises 50 to 95% by weight of biodegradable aromatic aliphatic polyester resin A and 5 to 50% by weight of biodegradable aromatic aliphatic polyester resin B. Method for manufacturing thermoformed products. Method for producing a thermoformed article of claim 7 or claim 8, characterized in that the thermoforming sheet temperature T ₁ of the time of preheating terminates preliminarily heated until the temperature which satisfies the following equation 3.
Glass transition temperature Tg + 35 ° C. of biodegradable aromatic aliphatic polyester resin A
≦ T ₁ ≦ Melting point of biodegradable aromatic aliphatic polyester resin A Tm−60 ° C. Formula 3 Method for producing a thermoformed article of claim 7 or claim 8, characterized in that the temperature T ₁ of the time of preheating ends thermoforming sheet is preheated so as to satisfy the following equation 4.
Glass transition temperature Tg + 65 ° C. of biodegradable aromatic aliphatic polyester resin A
≦ T ₁ ≦ Melting point of biodegradable aromatic aliphatic polyester resin A Tm−70 ° C. Formula 4 Method for producing a thermoformed article as claimed in any one of claims 7 to 10, characterized heating temperature T ₂ of the mold to a temperature which satisfies the following equation 5, to hold.
Glass transition temperature Tg + 55 ° C. of biodegradable aromatic aliphatic polyester resin A
≦ T ₂ ≦ Melting point of biodegradable aromatic aliphatic polyester resin A Tm−40 ° C. Formula 5 The method for producing a thermoformed article according to any one of claims 7 to 11, wherein the thermoforming sheet is brought into contact with the mold for 3 to 10 seconds. The method for producing a thermoformed product according to any one of claims 7 to 12, wherein the thermoforming sheet is brought into contact with the forming die for 3 to 6 seconds. The resin composition contains 50 parts by weight or less of a polylactic acid resin with respect to 100 parts by weight of the total amount of the biodegradable aromatic aliphatic polyester resin A and the biodegradable aromatic aliphatic polyester resin B. The method for producing a thermoformed product according to any one of claims 7 to 13. The thermoformed article according to any one of claims 1 to 6, wherein the thermoformed article is obtained by thermoforming a heat-softened thermoforming sheet. The thermoformed product according to claim 15, which is a thermoformed product obtained by thermoforming a heat-softened sheet for thermoforming brought into contact with a shaping surface of a mold. 17. The thermoformed product obtained by thermoforming a heat-softened sheet for thermoforming that is squeezed along either or both of the shaping surfaces of the female mold and the male mold. Thermoformed product. The heat-softened sheet for thermoforming is squeezed along the shaping surface of one or both of the female mold and the male mold, and brought into contact with the shaping surface of either the female mold or the male mold or both. The method for producing a thermoformed article according to any one of claims 7 to 14, wherein the forming is performed.

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