JP7253331B2 - Molded sheet of thermoplastic starch/olefin resin composition and method for producing same - Google Patents

Description

The present invention relates to a molded sheet of a thermoplastic starch/olefinic resin composition and a method for producing the same. More specifically, the present invention relates to a molded sheet of a thermoplastic starch/olefin-based resin composition which has no decrease in mechanical strength, is excellent in secondary workability such as vacuum molding, and has suppressed coloring, and a method for producing the same. be.

From the viewpoint of reducing carbon dioxide emissions that contribute to global warming, the possibility of using reproducible plant-derived components such as cellulose and starch has been investigated in various technical fields. In the field of resin molding technology, it has long been practiced to add plant-derived components as fillers to general-purpose thermoplastic resins such as polyolefins. However, simply mixing a plant-derived component causes a problem that the mechanical strength such as the impact strength of the thermoplastic resin is lowered, and the resin may be colored or deteriorated due to heat during processing. For example, Patent Document 1 discloses calender molding a polyolefin resin composition containing cornstarch. However, Patent Document 1 does not refer to improvement of the impact strength of the polyolefin resin composition.

As one method for improving the impact strength of thermoplastic resins, a method using a polymer alloy using thermoplastic starch (TPS) has been proposed in recent years. As means for improving the mechanical properties of thermoplastic resins using TPS, Patent Document 2 discloses a resin composition comprising starch, polyolefin resin, polyhydric alcohol which is liquid at room temperature, surfactant and compatibilizer. disclosed. It is described that the composition is processed by a known processing method to obtain a thermoplastic resin composition molded article having good mechanical properties. However, Patent Document 2 does not mention a method for solving the problem of coloring during processing of the resin composition.

On the other hand, the calender molding method is a sheet molding method with a higher yield than the T-die molding method, and is frequently used for the production of soft polyvinyl chloride resin sheets. However, it has been difficult to apply the calender molding method to the olefin-based resin because it is difficult to control the releasability of the olefin-based resin due to its winding or biting into the roll during processing. In order to deal with this problem, Patent Documents 1 and 3 propose the use of polyolefin-based resin compositions with limited composition and resin physical properties, but the scope of application is narrow and insufficient.

JP-A-2002-302582 JP 2016-210824 A JP-A-2000-143933

Under such circumstances, the problem to be solved by the present invention is to provide a molded sheet of an olefin-based resin composition containing thermoplastic starch, which suppresses coloration during sheet molding and has improved moldability and durability. and to provide a method for producing the same.

In view of the actual situation, the present inventors have made intensive studies and found that an olefin resin composition containing thermoplastic starch in a specific ratio is suitable for calendering, and that calendering can improve thermoplasticity. The inventors have found that it is possible to solve the drawbacks of olefinic resin compositions containing modified starch, such as discoloration due to shear heat during molding, deterioration of mechanical strength, and deterioration of vacuum moldability, and completed the present invention.

That is, the present invention is a sheet obtained by calender molding an olefinic resin composition (I) containing 20 to 70% by weight of a thermoplastic starch (II).
Further, the present invention provides a molded sheet obtained by calender molding an olefinic resin composition (I) containing a starch (A), a polyhydric alcohol (B) and an olefinic resin (C), wherein the starch (A) and the polyhydric alcohol (B) in a weight ratio (B/A) of 10/90 to 40/60.
Further, in the present invention, starch (A), polyhydric alcohol (B) and olefinic resin (C) are melt-kneaded to form an olefinic resin composition, and the olefinic resin composition is supplied to calender rolls. , a method for producing a formed sheet, including the step of rolling into a sheet shape.

FIG. 1 is a drawing showing an example of a calendering machine used in the calendering method. FIG. 2 is a drawing showing another example of a calendering machine used in the calendering method.

One embodiment of the present invention is a molded sheet obtained by calender molding an olefinic resin composition (I) containing 20 to 70% by weight of a thermoplastic starch (II). The olefinic resin composition (I) used in the molded sheet of the embodiment is obtained by mixing thermoplastic starch (hereinafter sometimes referred to as "TPS") (II) and an olefinic resin. composition. Starch consists of amorphous amylose, which is a long-chain molecule with a molecular weight of several tens of thousands, and amylopectin, which has a semi-crystalline structure with a molecular weight of several hundred thousand and a granular structure. Starches do not develop thermoplastic properties until temperatures leading to thermal denaturation. By heating and kneading starch together with a plasticizer, the granular structure is destroyed, the homogeneity is improved and the degree of crystallinity is lowered, and TPS enables thermoplastic processing in the same manner as general-purpose thermoplastic resins. A method for manufacturing TPS is described in, for example, the above-mentioned Patent Document 2.

In the olefinic resin composition (I) used in one embodiment of the present invention, the TPS content is 20-70% by weight, preferably 25-65% by weight, more preferably 30-60% by weight. If this proportion is 70% by weight or more, the mechanical properties of the olefin-based resin composition molding may be insufficient. As described above, TPS is a hydrophilic polymer composition containing a water-soluble plasticizer and has poor water resistance. This drawback can be overcome by blending with a highly hydrophobic polyolefin resin, but if it is blended in an olefin resin composition at a high blending ratio of 70% by weight or more, problems may occur in the water resistance of the composition. be. On the other hand, if the blending ratio of TPS in the olefinic resin composition is 20% by weight or less, calendar moldability becomes insufficient. It causes a problem in moldability in calender molding, and is not preferable from the viewpoint of utilization of plant-derived components. In calender molding, various properties are required such as winding, biting, and releasability of the resin composition around the roll. In general, polyolefin resins are not suitable for calender molding because their melt viscosities are highly dependent on temperature and their fluidity tolerance is low. As in the embodiment, the calender moldability can be improved by adding TPS to the polyolefin resin. The reason for this is not clear, but the flow characteristics suitable for calender molding are obtained by blending the highly polar, highly cohesive TPS melt with the polyolefin resin melt, which is highly hydrophobic and has low cohesive force. is assumed to be obtained.

On the other hand, the olefinic resin composition (I) used in the embodiment is a resin composition comprising starch (A), polyhydric alcohol (B) and olefinic resin (C). Olefin-based resin composition (I) may contain a surfactant (D), if necessary. Examples of the commercially available olefin resin composition (I) used in the embodiment include NEOPLA S-SERIES manufactured by Shiraishi Biomass Co., Ltd., and the production method thereof is described in Patent Document 2.

The melt flow rate (MFR) of the olefin-based resin composition (I) used in the embodiment is, from the viewpoint of preventing poor appearance of the molded article and reduction in impact strength, and maintaining secondary workability such as vacuum molding, It is preferably 0.01 to 10 g/10 minutes, more preferably 0.05 to 5 g/10 minutes, still more preferably 0.1 to 3 g/10 minutes. The MFR is a value measured at 190° C. under a load of 2.16 kg according to JIS K7210-1.

The melting point (Tm) of the olefin-based resin composition (I) used in the embodiment is preferably 90 from the viewpoint of improving the appearance of the molded product and increasing the mechanical strength such as rigidity and impact strength. ~155°C, more preferably 100 to 145°C, more preferably 105 to 140°C.

Here, the melting point (Tm) is the peak temperature of the peak with the maximum endothermic amount in the melting endothermic curve measured according to the following method.
Using a differential scanning calorimeter (for example, differential scanning calorimeter DSC6200 manufactured by Hitachi High-Tech Science Co., Ltd.), 5 mg of the specimen was heated in advance at 180 ° C. for 10 minutes in a nitrogen atmosphere to melt the specimen. The temperature is lowered to 30°C at a temperature lowering rate of °C/min. Thereafter, the temperature is raised at a rate of 10° C./min, and the peak temperature of the maximum endothermic amount in the obtained melting endothermic curve is defined as the melting point (Tm). The point at which the melting of indium (In) starts measured at a heating rate of 10°C/min using this measuring instrument was 156.2°C.

As the starch (A) used in the embodiment, any industrially distributed starch can be used, and either naturally occurring starch or modified starch can be used. Examples of naturally occurring starches include cornstarch, wheat starch, potato starch, sweet potato starch, and tapioca starch, but cornstarch is preferably used because of its large distribution and stable quality. Examples of modified starch include acetylated starch, phosphorylated starch, oxidized starch, hydroxypropyl starch, etc. Among these, phosphorylated starch having a phosphorus content of 0.5% or less is preferably used.

A polyhydric alcohol (B) can be used as a starch plasticizer when producing the TPS used in the embodiments. Preferred are polyhydric alcohols that are liquid at room temperature (preferably have a melting point lower than 25°C and a boiling point higher than 25°C), which have a large effect of plasticizing starch. Polyhydric alcohols that are liquid at room temperature for producing the TPS used in the embodiments include glycerin, diglycerin, polyglycerin, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (molecular weight: 200, molecular weight: 300, molecular weight: 400, molecular weight 600), 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentanediol. It is particularly preferred to use glycerin. One of these polyhydric alcohols can be used, or a mixture of multiple polyhydric alcohols can be used. If necessary, a polyhydric alcohol that is liquid at normal temperature and a polyhydric alcohol that is solid at normal temperature can be used together. Examples of polyhydric alcohols that are solid at room temperature include glucose, fructose, sorbitol, sucrose, trehalose, maltose and the like, with sorbitol being particularly preferred.

In the production of TPS used in the embodiment, the blending ratio of starch (A) and polyhydric alcohol (B) is such that the weight ratio (B/A) of component (B) to component (A) is 10/90 to 40. /60 is preferable. If the blending ratio of the polyhydric alcohol (B) is less than 10% by weight, the disintegration of the crystal granules during the production of TPS may be insufficient, and the plasticization of the obtained TPS may be insufficient. On the other hand, if the blending ratio of the polyhydric alcohol is more than 40% by weight, the strength of the molded product of the TPS-containing olefin resin composition may decrease and the surface may become sticky.

The olefinic resin (C) used in the embodiment is a resin composed of a homopolymer of one olefin or a copolymer of two or more olefins. The olefinic resin (C) does not include resins modified with unsaturated carboxylic acids or unsaturated carboxylic acid derivatives. The olefin-based resin (C) includes propylene-based resin (E) and ethylene-based resin (F). These polyolefin-based resins may be used alone, or two or more of them may be used in combination. Preferably, the propylene-based resin (E) and the ethylene-based resin (F) are mixed and used.

The propylene-based resin (E) used in the embodiment includes a propylene homopolymer, a propylene-ethylene random copolymer, a propylene-α-olefin random copolymer, and a copolymer obtained by homopolymerizing propylene and then copolymerizing ethylene and propylene. propylene block copolymers obtained by

The melting point (Tm) of the propylene-based resin (E) used in the embodiment is preferably 90 to 160 from the viewpoint of improving the appearance of the molded product and increasing the mechanical strength such as rigidity and impact strength. °C, more preferably 100 to 155°C, more preferably 105 to 155°C.
The melting point (Tm) is the peak temperature at which the endothermic amount is maximum in the melting endothermic curve measured according to the method described above.

The propylene-based resin (E) used in the embodiment can be produced by a solution polymerization method, a slurry polymerization method, a bulk polymerization method, a gas phase polymerization method, or the like. Moreover, these polymerization methods may be used alone, or two or more of them may be used in combination. As a method for producing the propylene-based resin (E), for example, "New Polymer Production Process" (edited by Koji Saiki, Industrial Research Institute (published in 1994)), JP-A-4-323207, JP-A-61-287917 Polymerization methods described in JP-A-2003-206464 can be mentioned.

A commercially available resin can be used as the propylene-based resin (E) used in the embodiment. Commercially available propylene-based resins (E) include Novatec PP, Wintec, Wellnex, and Waymax manufactured by Japan Polypropylene Corporation, Prime Polypro manufactured by Prime Polymer Co., Ltd., and Noblen and Excelen manufactured by Sumitomo Chemical Co., Ltd. etc.

Examples of the ethylene-based resin (F) used in the embodiment include, for example, high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, and α-olefins having 4 or more carbon atoms. and an α-olefin resin as an important component. The melting point (Tm) of the ethylene-based resin (F) used in the embodiment is preferably 60 to 160 from the viewpoint of improving the appearance of the molded product and increasing the mechanical strength such as rigidity and impact strength. °C, more preferably 70 to 150°C, even more preferably 80 to 140°C. The melting point (Tm) is the peak temperature at which the endothermic amount is maximum in the melting endothermic curve measured according to the method described above.

The ethylene-based resin (F) used in the embodiment can be produced by the same method as the above-described method for producing the propylene-based resin (E). A commercially available resin can be used as the ethylene-based resin (F) used in the embodiment. Commercially available ethylene-based resins (F) include Nippon Polyethylene Co., Ltd., Novatec, Harmolex, Kernel, Prime Polymer Co., Ltd. Evolue, Evolue H, Hi-Zex, UltoZex, and Sumitomo Chemical Co., Ltd. Examples include Excellen and Sumikasen.

The olefin-based resin (C) used in the embodiment can be used by appropriately adjusting the compounding ratio of the propylene-based resin (E) and the ethylene-based resin (F) according to the properties required for the secondary molded product. can.

The olefinic resin (C) used in the embodiment is preferably mixed with a modified olefinic resin (G) as a compatibilizer to improve compatibility with TPS.

The modified olefin resin (G) is obtained by modifying an olefin resin with at least one compound selected from the group consisting of unsaturated carboxylic acids and unsaturated carboxylic acid derivatives. Here, the olefinic resin that is the raw material of the modified olefinic resin (G) is a resin composed of a homopolymer of one kind of olefin or a copolymer of two or more kinds of olefins. In other words, the modified olefin resin (G) is selected from the group consisting of a homopolymer of one kind of olefin or a copolymer of two or more kinds of olefins and unsaturated carboxylic acids and unsaturated carboxylic acid derivatives. The resin is a resin produced by reacting at least one kind of compound, which has a partial structure derived from an unsaturated carboxylic acid or an unsaturated carboxylic acid derivative in the molecule. Examples of the modified olefin resin (G) include the following modified olefin resins (Ga) to (Gc). As the modified olefin resin (G), these modified olefin resins may be used alone, or two or more of them may be used in combination.

(Ga) A modified olefin resin obtained by graft polymerization of at least one compound selected from the group consisting of unsaturated carboxylic acids and unsaturated carboxylic acid derivatives onto an olefin homopolymer.
(Gb) Obtained by graft-polymerizing at least one compound selected from the group consisting of unsaturated carboxylic acids and unsaturated carboxylic acid derivatives to a copolymer obtained by copolymerizing two or more olefins. Modified olefin resin.
(Gc) At least one compound selected from the group consisting of unsaturated carboxylic acids and unsaturated carboxylic acid derivatives is added to a block copolymer obtained by homopolymerizing an olefin and then copolymerizing two or more olefins. Modified olefin resin obtained by graft polymerization.

The content of structural units derived from at least one compound selected from the group consisting of unsaturated carboxylic acids and unsaturated carboxylic acid derivatives contained in the modified olefin-based resin (G) affects impact strength, fatigue properties, rigidity, etc. From the viewpoint of mechanical strength, it is preferably 0.1 to 10% by weight. The content of structural units derived from at least one compound selected from the group consisting of unsaturated carboxylic acids and unsaturated carboxylic acid derivatives can be determined by infrared absorption spectrum or NMR spectrum. It can be determined by quantifying absorption based on at least one compound selected from the group consisting of acid derivatives.

As the modified olefin-based resin (G), a commercially available modified olefin-based resin may be used, including trade name Modiper (manufactured by NOF Corporation), trade name Blenmar CP (manufactured by NOF Corporation), and trade name Bond. Fast (manufactured by Sumitomo Chemical Co., Ltd.), trade name Bondine (manufactured by Sumitomo Chemical Co., Ltd.), trade name Rexpearl (manufactured by Japan Polyethylene Co., Ltd.), trade name Admer (manufactured by Mitsui Chemicals, Inc.), trade name Modic AP (manufactured by Mitsubishi Chemical Co., Ltd.), trade name Polybond (manufactured by Crompton Co., Ltd.), trade name Yumex (manufactured by Sanyo Kasei Co., Ltd.), and the like.

When the olefin resin (C) and the modified olefin resin (G) are mixed and used, the content of the modified olefin resin (G) in the olefin resin composition (I) is 0.5 to 10% by weight. , preferably 1 to 5% by weight.

In embodiments, a surfactant can be used for the purpose of lowering the interfacial tension between the olefinic resin and the TPS to improve the melt-kneadability. Any of anionic, cationic, amphoteric and nonionic surfactants can be used as the surfactant (D) in the embodiment. From the viewpoint of improving the heat resistance of the olefin resin composition, it is preferable to use an anionic, amphoteric or nonionic surfactant. Moreover, it is also possible to mix and use a plurality of types of surfactants. From the viewpoint of improving compatibility between the olefin resin and TPS, it is particularly preferable to use a nonionic surfactant having an HLB value of 3-9.

The blending amount of the surfactant (D) is 0.5 to 7% by weight, preferably 1.0 to 5% by weight, based on the olefinic resin (C) used in the embodiment. When the amount is less than 0.5% by weight, it is difficult to obtain the effect of improving the mechanical properties by improving the compatibility. Stickiness may develop.

In addition, the olefin resin composition (I) used in the embodiment may contain known substances that are generally added to olefin resins, such as antioxidants, heat stabilizers, neutralizers, and ultraviolet absorbers, depending on the purpose. Stabilizers such as agents, anti-foaming agents, flame retardants, flame retardant aids, dispersants, antistatic agents, lubricants, anti-blocking agents such as silica, coloring agents such as dyes and pigments, plasticizers, nucleating agents and crystals You may mix|blend an accelerator.

Plate-like or powder-like inorganic compounds such as glass flakes, mica, glass powder, glass beads, talc, clay, alumina, carbon black and wolsnite, and whiskers may also be added.

Moreover, one or more elastomers may be blended as necessary. Elastomers include ethylene/α-olefin random copolymers, ethylene/α-olefin/non-conjugated polyene random copolymers, hydrogenated block copolymers, other elastic polymers, and mixtures thereof. .

The olefin-based resin composition (I) used in the embodiment is produced by adding starch (A), polyhydric alcohol (B), olefin-based resin (C), and optionally surfactant (D) and other additives. The ingredients may be added together, in order, or separately into a Banbury mixer, kneader, Henschel mixer, single-screw or multi-screw extruder, and melt-kneaded at 80°C to 230°C. can. Through this process, the plasticizer enters the inside of the starch granules and destroys their regular structure, resulting in a homogeneous and heat-fluid TPS, and the olefinic resin and TPS are melt-kneaded to form a homogeneous olefinic resin composition (I ) is formed.

In the method used in the production of the molded sheet of the embodiment, the olefin resin composition (I) is melt-kneaded with a Banbury mixer, kneader, single-screw extruder, twin-screw extruder, or the like, and then supplied to calendar rolls, It is a calender forming method that rolls into a sheet of a predetermined thickness. The roll arrangement system includes a series type, an inclined type, an L type, an inverted L type, a Z type and an inclined Z type. and Z-type, more preferably inverted L-type.

As an example of the calendering method used in the production of the molded sheet of the embodiment, there is a method using a calendering machine 10A shown in FIG. In FIG. 1, the calendering machine 10A is an inverted L calendering machine having four rolls (roll 11a, roll 11b, roll 11c, and roll 11d) arranged in an inverted L shape. The three rolls (roll 11a, roll 11b, roll 11c, and roll 11d) are rotated in the directions of the arrows shown in FIG. 1 by driving devices (not shown). Further, each of the rolls 11a and 11b has a driving device (not shown), and the inter-roll distance d1 can be set to an arbitrary distance. Further, each of the rolls 11b and 11c has a driving device (not shown), and the inter-roll distance d2 can be set to an arbitrary distance. Further, each of the rolls 11c and 11d has a driving device (not shown), and the distance d3 between the rolls can be set to an arbitrary distance. The four rolls (roll 11a, roll 11b, roll 11c, and roll 11d) can each be set to a predetermined temperature by a heating device (not shown). The calender molding machine 10A can mold the melt-kneaded material melt-kneaded by the melt-kneading device 12 (Banbury kneader) into a sheet. Note that the melt-kneading device 12 does not have to be a Banbury kneader, and any melt-kneading device can be used.

Another example of the calender forming method used in manufacturing the formed sheet of the embodiment is the method using the calender forming machine 10B shown in FIG. In FIG. 2, the calendering machine 10B is a so-called two-roll type having a pair of rolls (roll 11e, roll 11f). A pair of rolls (roll 11e, roll 11f) are arranged horizontally. A pair of rolls (roll 11e, roll 11f) are rotated in opposite directions by driving devices (not shown). Moreover, a pair of rolls (roll 11e, roll 11f) is provided with a driving device (not shown), respectively, and the inter-roll distance d4 can be set to an arbitrary distance. Further, the temperature of the surface of each of the pair of rolls (roll 11e, roll 11f) can be set to a predetermined temperature by a heating device (not shown). The calendering machine 10B can melt-knead the raw material put on a pair of rolls (roll 11e, roll 11f) and form the melt-kneaded material 13 into a sheet.

The calendering machine used in manufacturing the molded sheet of the embodiment is not limited to the calendering machines illustrated in FIGS. 1 and 2 . For example, the calendering machine may have two rolls, three rolls, or four or more rolls. Also, the calendering machine can use rolls of any diameter. Further, the calender molding machine 10B of FIG. 2 may be provided with a melt-kneading device 12 for melt-kneading the raw materials. 1 and 2 (calendar molding machine 10A, calender molding machine 10B) may be provided with a raw material crushing device. 1 and 2 (calender forming machine 10A, calender forming machine 10B) may be equipped with a cooling device such as a cooling roll.

In the calendar molding used in the production of the molded sheet of the embodiment, the resin temperature is preferably 100 to 200° C., more preferably 120 to 180° C., from the viewpoint of good moldability and good appearance and color of the sheet. and more preferably 130 to 160°C.

In the calender molding method used in the production of the molded sheet of the embodiment, the temperature of the cooling roll is preferably 5 to 100° C., more preferably 10 to 90° C., from the viewpoint of good sheet appearance and productivity. °C, particularly preferably 15 to 80°C. In addition, it is preferable to install several cooling rolls after the calender roll, so that the resin can be gradually cooled step by step, so that adhesion of the resin can be effectively prevented.

In the calender molding method used in the production of the molded sheet of the embodiment, the calender molding speed is preferably 5.0 to 80 m/min. and more preferably 10 to 50 m/min. and particularly preferably 15 to 30 m/min. is.

In the calender molding method used in the production of the molded sheet of the embodiment, the width of the sheet is preferably 200 to 2000 mm, more preferably 300 to 1500 mm, in terms of efficiency of sheet production and ease of secondary processing. , particularly preferably 500 to 1300 mm.

In the calender molding method used in the production of the molded sheet of the embodiment, the thickness of the sheet is preferably 0.1 to 2.0 mm, more preferably 0, from the efficiency of sheet production and ease of secondary processing. .2 to 1.2 mm, particularly preferably 0.4 to 1.0 mm.

The present invention will now be described with reference to examples and comparative examples. A method for manufacturing evaluation samples used in Examples or Comparative Examples is described below.

(1) TPS-blended olefin resin composition for evaluation NEOPLA-S-157(a-1) manufactured by Shiraishi Biomass Co., Ltd. manufactured by the method described in Patent Document 2 was used. The outline of NEOPLA-S-157(a-1) is as follows.
・Melting point: 117.7°C,
・MFR: 0.2 g/10 minutes (190°C, 2.16 kg load)
・TPS content: 51% by weight

(2) Example 1: Calender molding method for evaluation samples Using a 24-inch inverted L-type four calendar manufactured by Nippon Roll Co., Ltd., NEOPLA-S-157 (a-1) was formed under the following conditions. 1 sample was prepared.
Seat width: 580mm
Roll temperature: No. 1, No. 2 rolls 150°C
No. 3, No. 4 rolls 140°C
Cooling roll temperature: 10-25°C
Line speed: 16 m/min Sheet thickness: 0.8 mm

(3) Comparative Example 1: T-die extrusion molding method for evaluation samples Using the following Hitachi Zosen molding machine, under the following conditions, the NEOPLA-S-157 (a-1) of (1) above was subjected to a T-die. Comparative Example 1 samples were produced by extrusion.
Extruder: T-die extruder manufactured by Hitachi Zosen, screw diameter: 120 mm
Screw type: Full flight Molding conditions: Air knife method Cylinder setting temperature: 180°C
First roll set temperature: 30°C
Take-up speed: 3m/min Sheet width: 580mm
Sheet thickness: 0.8mm
Evaluation methods for the samples of Example 1 and Comparative Example 1 are shown below.

(1) Yellowness YI (unit: -)
A plate (cardboard: white, YI: 0.79) was placed on the back surface of the sample, and the tristimulus value of each sheet was measured by reflection measurement to calculate YI (ASTM D1925).
Apparatus: Photometer SQ-300H manufactured by Nippon Denshoku Kogyo Co., Ltd.
Light source: C/2
Color system: XYZ color system (2) Vacuum formability A sheet was formed under the following conditions and evaluated.
Molding conditions: The sheets obtained in Example 1 and Comparative Example 1 were preheated at 250° C. for 30 seconds and then shaped by vacuum molding.
Tray shape: A tray with four recesses of 287 mm long x 91 mm wide and 50 mm deep in a 310 mm long and 410 mm wide Criteria:
Good: No thickness unevenness, twists, or tears were observed Poor: Thickness unevenness, twists, or tears were observed

The TPS-blended olefinic resin composition could be formed into a sheet by either the calendar molding method or the T-die molding method. However, the sheet formed by the T-die molding method of Comparative Example 1 had a high degree of yellowness. Further, it was found that the sheet of Comparative Example 1 was difficult to be vacuum-formed. In contrast, the sheet of Example 1 produced by the calendering method had a low degree of yellowness and good vacuum formability.

Claims (5)

Olefin-based resin (C) containing 20 to 70% by weight of thermoplastic starch (II), which is a mixture of propylene-based resin (E) selected from propylene-ethylene random copolymers and ethylene-based resin (F) ), and has a melt flow rate of 0.1 to 3 g/10 minutes measured under a load of 2.16 kg at 190°C according to JIS K7210-1, and a melting point of 90 to 155°C. ) is formed by calender molding. The molded sheet according to claim 1, wherein the olefinic resin composition (I) further contains a surfactant (D). Starch (A), polyhydric alcohol (B) and propylene-ethylene random copolymer containing olefin-based resin (C) which is a mixture of propylene-based resin (E) and ethylene-based resin (F), According to JIS K7210-1, the olefin resin composition (I) having a melt flow rate of 0.1 to 3 g/10 minutes measured under a load of 2.16 kg at 190°C and a melting point of 90 to 155°C is calendered. A molded sheet formed by
The molded sheet, wherein the weight ratio (B/A) of the starch (A) and the polyhydric alcohol (B) is 10/90 to 40/60. Claim 3, wherein the olefin resin composition (I) further comprises a surfactant (D), and the surfactant is contained in an amount of 0.5 to 15% by weight relative to the olefin resin (C). Molded sheet as described. An olefin resin (C) which is a mixture of a propylene resin (E) selected from starch (A), a polyhydric alcohol (B), and a propylene-ethylene random copolymer and an ethylene resin (F) is melt-kneaded. Then, according to JIS K7210-1, an olefin resin composition (I) having a melt flow rate measured at 190°C under a load of 2.16 kg of 0.1 to 3 g/10 minutes and a melting point of 90 to 155°C. to form
supplying the olefin-based resin composition to calender rolls arranged in an inverted L-shape or Z-shape;
Cooling with a cooling roll at a temperature of 5 to 100 ° C.,
5.0-80 m/min. Forming at a calendering speed of and rolling into a sheet shape,
A method of manufacturing a formed sheet, comprising steps.

Images