JP5356736B2 - Thermoplastic resin composition containing liquid plasticizer, method for producing the same, and biodegradable extruded sheet or film using the thermoplastic resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic resin composition containing a liquid plasticizer that is used in molding a biodegradable sheet or film containing a polylactic acid and has substantially uniformly mixed components, to provide a process for producing the thermoplastic resin composition, and to provide a biodegradable extrusion-molded sheet or film using the thermoplastic resin composition. <P>SOLUTION: The thermoplastic resin composition comprises (A) a thermoplastic resin, (B) an inorganic filler having a weight-average particle diameter of not less than 0.1 &mu;m to not more than 10 &mu;m, the product of the weight average particle diameter (&mu;m) and the specific surface area (m<SP>2</SP>/g) of 10 or more and a boiled linseed oil absorption of not less than 40 ml/100 g and (C) a liquid plasticizer and is prepared so that the component (A) is composed of a polylactic acid at a blending ratio of not less than 10 wt.% to not more than 100 wt.%, a biodegradable aliphatic polyester at a blending ratio of not less than 10 wt.% to not more than 90 wt.% and a biodegradable aliphatic/aromatic polyester at a blending ratio of not less than 0 wt.% to not more than 90 wt.%; the ratio (B):(C) of pts.wt. of the component (B) to the component (C) is 99:1 to 50:50; and the blending ratio of the component (C) is not less than 5 pts.wt. to not more than 50 pts.wt. based on 100 pts.wt. of the polylactic acid in the component (A). <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention relates to a thermoplastic resin composition containing a liquid plasticizer, a method for producing the thermoplastic resin composition, which is used when a biodegradable sheet or film containing polylactic acid is formed by an extrusion molding method, and The present invention relates to a biodegradable sheet or film extruded using the thermoplastic resin composition. More specifically, the present invention relates to a thermoplastic resin composition including a thermoplastic resin composed of polylactic acid or other biodegradable resin, a liquid plasticizer, and an inorganic filler.

In recent years, interest in environmental problems has increased, and the demand for molded products using biodegradable resins has increased. Among them, polylactic acid has attracted much attention as a biomass-derived resin, and it is desired to provide a film or sheet containing polylactic acid.

However, aliphatic polyesters such as polybutylene succinate, which is another biodegradable resin, and aliphatic aromatic polyesters such as polybutylene adipate terephthalate, can be molded into a flexible resin molded product without the addition of a plasticizer. On the other hand, polylactic acid can form only a molded product that is hard and unsuitable for bending or the like when a plasticizer is not used. Therefore, various attempts have been made to produce flexible resin molded products using polylactic acid.

For example, the following Patent Document 1 discloses a polylactic acid resin composition containing a lactic acid polyester and a plasticizer prepared by adjusting a lactic acid component and a polyester component to have a specific weight ratio, and a film and the like using the same. Is disclosed. Patent Document 2 below discloses an invention of a polylactic acid film comprising a polymer containing polylactic acid, a biodegradable aliphatic polyester having a glass transition point of 0 ° C. or less, and a plasticizer. As described in Patent Document 1 or 2, it has been attempted to impart flexibility to a polylactic acid-containing resin molded product by blending a resin capable of forming a flexible molded product with polylactic acid. .

  Furthermore, in Patent Document 3, molding is performed using a resin composition comprising polylactic acid, a biodegradable aliphatic-aromatic copolymer polyester having a glass transition temperature of 0 ° C. or less, a plasticizer, and an inorganic filler. An invention of a polylactic acid-based film is disclosed. In the invention described in Patent Document 3, polylactic acid is blended with other biodegradable polyester to give flexibility, and a plasticizer is used, and a general inorganic filler is further contained. It has the characteristics.

JP 2007-138187 A JP 2000-273207 A JP 2002-327107 A

By the way, there are various methods for molding a resin molded product, but the extrusion molding method is a very general method, and there is a demand for molding a polylactic acid-containing resin molded product with a general-purpose extrusion molding apparatus. high. In such a case, the resin composition is generally prepared in advance by using a mixer or the like, and this is put into a hopper of an extruder.

However, when a compound is prepared using the polylactic acid-containing resin composition disclosed in Patent Documents 1 to 3, there are the following problems.

  That is, in Patent Document 1 or 2, a plasticizer is further used after blending a resin capable of imparting flexibility to a molded product and polylactic acid. The plasticizer used in such a case is generally liquid. However, when the content of the liquid plasticizer exceeds about 5% in the resin composition, stickiness occurs during compounding of the resin composition, and the resin There was a tendency for them to bind together and form a lump. In addition, the resin in a lump may cause clogging or adhesion to the apparatus at the introduction part or inside of the mixer, or the liquid plasticizer may not be well mixed with the resin and separated to cause a liquid pool. was there. In addition, in a sticky state, the resin and the liquid plasticizer are difficult to be mixed uniformly, and in the resin melt kneading step in compounding, there is a problem that the components of the resin composition such as the liquid plasticizer are difficult to be mixed uniformly. For this reason, the molten resin pressure is not constant, which is a cause of poor moldability. In addition, there was a problem that the workability of compounding was poor.

  In addition, as disclosed in Patent Document 3, even when a general inorganic additive is contained in a polylactic acid-containing resin composition, the components of the resin composition are mixed at the time of compounding the resin composition. When they are mixed, they tend to harden in the form of clay and have the same problems as described above.

  And, as described above, due to poor mixing during compounding of the resin composition, the obtained compound (that is, the resin composition after mixing) has an uneven composition, and the resin molded using this compound This has caused variations in physical properties and shapes of molded products.

  As another trial, for example, using a method disclosed in Japanese Patent Publication No. 47-40852 or Japanese Patent Publication No. 46-10998, a side feed device is provided in the extrusion molding apparatus, and the hopper is inserted into the extrusion molding apparatus. It is also conceivable that a resin material is masterbatched in an extrusion molding apparatus by adding a liquid plasticizer from the side feed apparatus to the supplied resin and mixing them.

  However, in the above-described method, a special extrusion molding apparatus including a side feed device is required, and as a result, the cost for the apparatus increases. As a result, the price of the obtained molded product has to be increased, which is a problem in terms of cost.

  The present invention has been made in view of the above problems. More specifically, the present invention relates to a thermoplastic resin composition containing a liquid plasticizer used when a biodegradable sheet or film containing polylactic acid is molded. There are provided a thermoplastic resin composition in which constituent components are substantially uniformly mixed, a method for producing the thermoplastic resin composition, and a biodegradable extruded sheet or film using the thermoplastic resin composition. It is for the purpose.

  When mixing the thermoplastic resin component containing polylactic acid and the liquid plasticizer, the inventor further uses a specific inorganic filler, and by mixing these simultaneously, the liquid plasticizer and The present inventors have found that a thermoplastic resin composition in which constituent materials of a resin composition such as a thermoplastic resin are mixed substantially uniformly can be obtained, and the present invention has been completed.

That is, the present invention
(1) (A) a thermoplastic resin and (B) a weight average particle diameter of 0.1 μm or more and 10 μm or less, and a product of the weight average particle diameter (μm) and specific surface area (m ² / g) is 10 or more, And boiled linseed oil absorption amount of 40 ml / 100 g or more, an inorganic filler in which the particle surface is composed of irregular irregularities and has a petal shape or a spot shape, and (C) a liquid plasticizer. And the above (A) is a polylactic acid of 10% by weight to 100% by weight, a biodegradable aliphatic polyester of 0% by weight to 90% by weight, and a biodegradable aliphatic aromatic polyester of 0% by weight to 90% by weight. It is comprised by the following compounding ratios, The ratio of the weight part of said (B) and said (C) is (B) :( C) = 99: 1 thru | or 50:50, and said (A ) With respect to 100 parts by weight of polylactic acid in (C) a thermoplastic resin composition containing a liquid plasticizer, wherein the blend ratio is 50 parts by weight or more 5 parts by weight of,
(2) The above (A) is composed of polylactic acid and an aliphatic polyester and / or an aliphatic aromatic polyester. The polylactic acid is 10% by weight to 90% by weight, and the aliphatic polyester is 10% by weight to 90%. A thermoplastic resin composition containing the liquid plasticizer according to (1) above, wherein the thermoplastic resin composition is composed of a blending ratio of 10% by weight or more and 90% by weight or less of an aliphatic aromatic polyester,
(3) The thermoplastic resin composition containing the liquid plasticizer according to (1) or (2), wherein the inorganic filler is calcium carbonate,
(4) A thermoplastic resin composition is produced by simultaneously mixing (A), (B) and (C) described in any one of (1) to (3) above. A method for producing a thermoplastic resin composition containing a liquid plasticizer,
(5) A biodegradable extruded sheet or film having a tensile elastic modulus of 1200 MPa or less, formed using the resin composition containing the liquid plasticizer according to any one of (1) to (3) above ,
Is a summary.

  The present invention relates to a liquid plasticizer that is added to give flexibility to a resin molded product molded using a resin composition containing polylactic acid by blending a specific inorganic filler into the resin composition. Even when the resin composition is present, the occurrence of stickiness during compounding of the resin composition can be satisfactorily prevented. Therefore, problems such as poor mixing of the resin composition at the time of compounding, adhesion to the mixing apparatus, clogging or liquid pool in the mixing apparatus, which has been a problem in the past, can be satisfactorily prevented. Therefore, the workability in compounding is very good, the cleaning of the system of the apparatus used for compounding is very easy, and the switching work for molding different resin molded products is performed efficiently. .

  In addition, as described above, the resin composition of the present invention enables substantially uniform mixing in compounding. Therefore, in a resin molded product molded using the obtained compound, the resin composition is caused by poor mixing of the resin composition. There is no risk of variations in physical properties and shapes.

And since the liquid plasticizer is well added and dispersed in the resin composition containing polylactic acid, in addition to the strength derived from polylactic acid, it provides molded products such as films and sheets that have favorable flexibility. can do. The film or sheet can exhibit very excellent flexibility with respect to a conventional polylactic acid-containing biodegradable resin molded product.

In addition, according to the present invention, as the particles of the specific inorganic filler, the particle surface is composed of irregular irregularities and has a rose petal shape or a garnet shape, which has an advantageous effect. Play. That is, according to the present invention, as the specific inorganic filler, a particle surface having irregular irregularities and having a rose petal shape or a corrugated shape is used, and the compounding of the resin composition The uneven portions of the inorganic filler particles are crushed by the shearing force of mixing in the melt mixing step at this time, and are further finely dispersed in the molten resin. As a result, the liquid plasticizer absorbed in the inorganic filler particles is dispersed more uniformly in the molten resin. By molding a resin molded product using a compound in which the liquid plasticizer is very well dispersed and mixed in this way, it is possible to provide a very high quality resin molded product with no unevenness in physical properties and shape.

  In particular, as the inorganic filler in the present invention, the one made of calcium carbonate is advantageous from the viewpoint of its handleability, availability, cost, etc. Among them, the calcium carbonate particles have irregular irregularities on the surface. It is desirable to use an inorganic filler composed of

In addition, the method for producing the thermoplastic resin composition of the present invention does not require the components of the resin composition to be mixed in several steps, and does not require the use of an expensive apparatus having a side feed. By mixing the components at once using a general-purpose mixing apparatus, the components can be uniformly mixed and a non-sticky compound can be produced. And the molded product shape | molded using the said compound in an extrusion molding apparatus does not have a composition nonuniformity, and shows a favorable physical property.

  The best mode of the thermoplastic resin composition containing the liquid plasticizer of the present invention (hereinafter also simply referred to as “resin composition of the present invention”) will be described below for each constituent material.

(Thermoplastic resin)
The thermoplastic resin used in the present invention is composed of polylactic acid as an essential component, and appropriately blended with a biodegradable aliphatic aromatic polyester or a biodegradable aliphatic polyester as necessary.

  The polylactic acid used in the present invention is a polymer formed by polymerizing lactic acid through an ester bond. In particular, those having a number average molecular weight of about 80,000 to 150,000 are preferably used. Lactic acid has one asymmetric carbon, and there are two types, L and D, so polylactic acid is poly L lactic acid obtained by polymerizing L lactic acid, and poly D lactic acid obtained by polymerizing D lactic acid. There is poly DL lactic acid obtained by copolymerizing L-form and D-form lactic acid. The polylactic acid of the present invention can be used in any of the above types, and may be used in combination. In particular, so-called stereocomplex polylactic acid mixed with poly L lactic acid and poly D lactic acid can exhibit higher heat resistance in the obtained molded product. On the other hand, poly DL lactic acid is known to have low crystallinity. Therefore, in the present invention, it is desirable to appropriately select and use the above polylactic acid in consideration of the properties required for the final product.

  Examples of the biodegradable aliphatic aromatic polyester used in the present invention include polybutylene adipate terephthalate (hereinafter also referred to as “PBAT”), polyethylene terephthalate, polybutylene succinate terephthalate, and polytetramethylene adipate terephthalate.

  Examples of the biodegradable aliphatic polyester used in the present invention include polybutylene succinate (hereinafter also referred to as “PBS”), polybutylene succinate adipate, polyethylene succinate, polyhydroxybutyric acid, polybutylene succinate carbonate, Examples include polycaprolactone.

  As the thermoplastic resin in the present invention, 100% by weight of the above polylactic acid can be used, or polylactic acid, a biodegradable aliphatic aromatic polyester and / or a biodegradable aliphatic polyester can be appropriately blended. Also good. More specifically, the biodegradable aliphatic polyester is 0% by weight to 90% by weight and / or the biodegradable aliphatic aromatic polyester is 0% by weight to 90% by weight with respect to 10% by weight to 100% by weight of polylactic acid. The said thermoplastic resin can be comprised by the mixture ratio of the weight% or less.

  In particular, when a resin molded product is molded using the resin composition of the present invention in which polylactic acid is used in an amount of more than 90% by weight and not more than 100% by weight as the above-mentioned thermoplastic resin, it is flexible enough to be molded. A molded article having high strength can be obtained. For this reason, it is possible to form a film or sheet that can be used as a material for the exterior of an electrical appliance. Moreover, since the thermoplastic resin contained in the resin composition of the present invention is composed of biodegradable polylactic acid or other biodegradable resin in addition to this, it is obtained by the present invention after use of the product. It can be disposed of by biodegradation, such as by embedding a film or sheet in the soil.

On the other hand, the composition is composed of a blending ratio of 10% by weight to 90% by weight of polylactic acid, 10% by weight to 90% by weight of aliphatic polyester, and 10% by weight to 90% by weight of aliphatic aromatic polyester. It is preferable in that a biodegradable film or sheet to which properties are imparted can be easily provided. That is, if the resin composition of the present invention obtained by blending polylactic acid and a plasticizer and further blending 10% by weight or more of another biodegradable resin with high flexibility, good flexibility It is possible to easily form a film or sheet showing Moreover, since the biodegradation rate differs between polylactic acid and other biodegradable resins, it is possible to adjust the biodegradation period according to the purpose by mixing these biodegradable resins. . Therefore, a film or sheet formed by using the resin composition of the present invention in which polylactic acid is mixed with biodegradable aliphatic polyester and / or biodegradable aliphatic aromatic polyester is used for a certain period of time, for example. It can be used very suitably for agricultural films (or sheets) that are desired to be biodegraded later.

  In the present invention, “biodegradation” strictly refers to decomposition into carbon dioxide and water over a certain period by microorganisms in the soil. The time until this decomposition depends on the molecular structure of the resin constituting the substrate, and it is generally known that a resin having a linear structure is decomposed in a shorter time. In addition, “biodegradable aliphatic aromatic polyester” or “biodegradable aliphatic polyester” means that when a resin molded product is molded using the resin, the molded product is embedded when buried in soil. It means to show degradability.

(Inorganic filler)
The inorganic filler used in the present invention can be selected from known inorganic fillers that can be used in resin molding, such as calcium carbonate and talc. However, it is limited to the following conditions.

It is important that the inorganic filler used in the present invention has a product of a weight average particle diameter (μm) and a specific surface area (m ² / g) of 10 or more. The present inventor investigated the correlation between the reciprocal of the weight average particle diameter (μm) and the specific surface area of calcium carbonate as an example in the research process for achieving the object of the present invention. Found a relationship. That is, spherical calcium carbonate with no irregularities on the surface, which is widely used as a filler, and almost no pores, shows the correlation between the reciprocal of its weight average particle diameter (μm) and the specific surface area, in the first quadrant. Formula 1 below
(Formula 1) y = 2.613x + 0.3823
Are substantially present on a straight line indicated by and are proportional to each other. On the other hand, some special calcium carbonate did not follow this straight line, but existed in the first quadrant above the straight line, that is, in a region having a large specific surface area value. In the figure, spherical general-purpose calcium carbonate having no irregularities on the surface and almost no pores is shown by a black diamond plot, and special calcium carbonate is shown by a white diamond plot.

  In other words, in the graph of FIG. 1, the general-purpose calcium carbonate existing in a straight line has a product of a weight average particle diameter and a specific surface area of about 2.0 to 2.3, and is expressed by Equation 1. The product of the weight average particle diameter and the specific surface area of special calcium carbonate existing in a region exceeding the straight line was more than 2 while it was substantially assembled on a straight line.

  As a result of further study on the product of the weight average particle size and the specific surface area, the present inventor has found that the product of the weight average particle size and the specific surface area is 10 or more, especially the boiled linseed oil absorption is 40 ml / 100 g. It was found that the above absorbability was very high. And if it is this inorganic filler, when it mixes with the thermoplastic resin mentioned above and a liquid plasticizer simultaneously, while the liquid plasticizer is fully absorbed in an inorganic filler, the inorganic filling which absorbed the liquid plasticizer Since the agent adheres to the surface of the thermoplastic resin and is well dispersed throughout the composition, the resulting thermoplastic resin composition does not become sticky. Therefore, when the compound of the thermoplastic resin composition is put into the hopper of the extrusion molding apparatus, the thermoplastic resins in the thermoplastic resin composition are not bound to each other and the hopper outlet is not clogged, and the liquid plasticizer A part of the liquid is not separated and a liquid pool is not formed. As a result, when pellets are formed by extrusion molding using the compound of the thermoplastic resin composition, very good extrusion moldability is exhibited, and compound pellets with no composition unevenness can be obtained.

  The boiled linseed oil absorption is measured according to the boiled linseed oil method defined in JIS K5101. The boiled linseed oil absorption amount of the inorganic filler that can be used in the present invention is 40 ml / 100 g or more, preferably 45 ml / 100 g or more, and more preferably 50 ml / 100 g or more.

  Further, in particular, by selecting an inorganic filler whose particle surface is composed of irregular irregularities, the product of the weight average particle diameter and the specific surface area is 10 or more, and the boiled linseed oil absorption amount is It turned out that the inorganic filler which can be used in this invention which shows 40 ml / 100g or more can be obtained easily.

  Of the inorganic fillers having a product of the weight average particle diameter and the specific surface area of 10 or more and boiled linseed oil absorption of 40 ml / 100 g or more, the particle surface is particularly composed of irregular irregularities. According to the use of the agent, in addition to the effect of obtaining a compound of a thermoplastic resin composition having no stickiness and excellent extrudability, there is an additional effect from its special shape. That is, when the compound of the thermoplastic resin composition of the present invention is fed into the screw part in the extrusion molding device, the inorganic filler is broken and melted by shearing stress so that at least a part of the inorganic filler having irregularities is crushed. More easily dispersed in the thermoplastic resin. At this time, since the liquid plasticizer is absorbed in the inorganic filler, as a result of the inorganic filler being dispersed in the molten resin, the liquid plasticizer is also dispersed at the same time. Excellent physical properties and shape are shown.

  Here, the inorganic filler whose particle surface is composed of irregular irregularities does not matter whether or not the particles are porous. Irregular irregularities on the particle surface can also be expressed as, for example, “rose petal” or “garlic”. For example, as commercially available products, porous calcium carbonate “CALLITE KT” manufactured by Shiroishi Calcium Co., Ltd., or precipitated calcium carbonate “ALBACAR 5970” manufactured by Pfematech Co., Ltd., etc., has irregular irregularities on the particle surface in the present invention. It can be used as an inorganic filler composed of

  The weight average particle diameter of the inorganic filler that can be used in the present invention is 0.1 μm or more and 10 μm or less. The preferable range of the weight average particle diameter was determined in consideration of good dispersibility in the thermoplastic resin composition, availability thereof, and the like. In particular, if the above-mentioned inorganic filler has a weight average particle size of 0.1 μm or more, it is large enough to achieve the object of the present invention and is not economically disadvantageous, and has a weight average particle size. When the thickness is 10 μm or less, the presence of particles on the surface of the molded product is not noticeable when the molded product is a film or sheet.

(Liquid plasticizer)
The liquid plasticizer in the present invention can be appropriately selected and used as long as it is a liquid additive at room temperature used for imparting flexibility to the thermoplastic resin. However, when a molded product molded using the thermoplastic resin composition of the present invention is biodegraded, the liquid plasticizer contained in the molded product is released into the environment. For example, it is desirable to use a highly safe liquid plasticizer. Examples of liquid plasticizers include glyceryl triacetate, glyceryl diacetomonolaurate, diisononyl adipate, poly (1,3-butanediol) adipate, benzyl = 2 (2-methoxyethoxy) ethyl = adipate, tributyl acetylcitrate And epoxidized soybean oil. The liquid plasticizer may be a single additive or a combination of two or more additives.

(About the blending ratio of the thermoplastic resin composition)
In the thermoplastic resin composition of the present invention, the blending ratio of the constituent components is specified as follows (A) the thermoplastic resin, (B) the inorganic filler, and (C) the liquid plasticizer. Is done. That is, the ratio by weight of (B) inorganic filler and (C) liquid additive is (B) :( C) = 99: 1 to 50:50, and (A) in the thermoplastic resin The blending ratio of (C) liquid plasticizer is 5 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of polylactic acid.

In the above blending ratio, even if the blending amount of the (C) liquid plasticizer is 5 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the polylactic acid in the (A) thermoplastic resin, ) When the ratio by weight of inorganic filler and (C) liquid additive is out of the range of (B) :( C) = 99: 1 to 50:50, (C) liquid plasticizer and absorb this (B) The balance with the inorganic filler is poor and the liquid plasticizer may be separated or the inorganic filler may not adhere well to the surface of the thermoplastic resin. It causes a defect.

Further, when the blending amount of (C) is less than 5 parts by weight with respect to 100 parts by weight of polylactic acid in (A) thermoplastic resin, there is a possibility that sufficient flexibility cannot be imparted to polylactic acid. On the other hand, if it exceeds 50 parts by weight, the liquid plasticizer may bleed. In addition, when mixing and using 2 or more types of liquid plasticizers, it adjusts so that the sum total of the weight may become the preferable mixture ratio of the (C) liquid plasticizer mentioned above.

  Moreover, you may add a desired additive to the thermoplastic resin composition of this invention according to the objective in the range which does not deviate from the meaning of this invention. Examples of the additive include a colorant, an ultraviolet absorber, an antioxidant, a light stabilizer, an antistatic agent, a hydrolysis inhibitor, an organic filler, and an inorganic filler. However, when these additives are used as a liquid material, the handling thereof shall be handled as the liquid plasticizer in the present invention described above. That is, the liquid plasticizer should be used within a preferable blending amount in the thermoplastic resin composition.

(About the manufacturing method of the thermoplastic resin composition of this invention)
The greatest feature of the method for producing a thermoplastic resin composition containing the liquid plasticizer of the present invention, that is, the method for producing a compound, is at least using a general-purpose mixing device or an extrusion molding device that can be used for producing a compound. The thermoplastic resin containing polylactic acid, the specific inorganic filler described above, and the liquid plasticizer can be mixed at the same time. In the present invention, the meaning of “mixing simultaneously” means that mixing can be performed in a single mixing step without dividing the mixing step of mixing the constituent materials of the resin composition into several times.

  The polylactic acid, biodegradable aliphatic aromatic polyester or biodegradable aliphatic polyester used as the thermoplastic resin in the present invention may be in the form of pellets or powder. In general, however, the thermoplastic resin is often in the form of pellets.

  Here, the pellet-shaped thermoplastic resin refers to a resin molded into a granular shape exceeding the dimension generally understood as a powder. The shape may be an arbitrary shape such as a substantially spherical shape, an elliptical shape, or a cylindrical shape. Also, the size is not particularly limited, but the maximum diameter is generally about 2 mm to 6 mm.

  As an apparatus used for mixing a thermoplastic resin having a pellet shape, the above-described specific inorganic filler, and a liquid plasticizer, these can be melt-mixed to produce a compound having a desired shape. Any suitable apparatus can be appropriately selected and used. For example, a generally used mixing apparatus such as a tumbler mixer or a Henschel mixer, or an extrusion apparatus that can also be used for producing a compound is used.

In the apparatus described above, the mixing temperature in the apparatus when mixing the thermoplastic resin, the liquid plasticizer, and the inorganic filler is sufficiently mixed even when the mixing temperature is about room temperature, and uniform thermoplasticity is achieved. A resin composition can be obtained. By adjusting the temperature to about 50 ° C. to 80 ° C., the liquid plasticizer is well absorbed by an inorganic filler such as calcium carbonate, and the inorganic filling absorbs the liquid plasticizer. The agent is preferable because it adheres well to the surface of the pellet-shaped resin composition. In the method for producing a resin composition of the present invention, as described above, the components of the resin composition are mixed at a temperature equal to or lower than the melting temperature of the thermoplastic resin, and the inorganic filler that has absorbed the liquid plasticizer is dispersed well throughout, Moreover, it is excellent in that a non-sticky compound can be produced simply by adhering to the surface of the pellet-shaped resin composition.

  Further, in the method for producing a thermoplastic resin composition of the present invention, the temperature in the mixing apparatus is adjusted to be equal to or higher than the melting temperature of the thermoplastic resin used, and the thermoplastic resin is once melted in the apparatus. By stirring in the state, the inorganic filler that has absorbed the liquid plasticizer can be kneaded into the resin and formed into a pellet shape again. More specifically, first, the constituents of the resin composition are stirred and mixed in advance using a Henschel mixer, a tumbler mixer, etc., and the liquid filler is absorbed by the inorganic filler, and the inorganic filler is mixed with a resin composition such as a pellet. Adhere to objects. Next, as described above, the pellets with the inorganic filler adhered to the surface are put into a melt-mixable apparatus such as an extrusion molding apparatus, the resin composition is melted, and the inorganic filler that has absorbed the liquid plasticizer is used as the resin. Compound pellets of the resin composition can be produced by kneading the mixture into the desired pellet shape.

In the present specification, a compound obtained by mixing the constituent materials of the thermoplastic resin composition of the present invention is called a compound, but the constituent materials of the thermoplastic resin composition of the present invention are mixed, melted and extruded. In some cases, the product formed into a pellet shape is sometimes called a “compound pellet”.

In the method for producing a thermoplastic resin composition of the present invention, the mixing time is appropriately determined depending on the total amount to be mixed, or the type of composition, temperature, type of mixing apparatus, and the like. Further, the stirring speed in the case of stirring using a screw, a stirring blade or the like at the time of mixing is also appropriately determined as described above. Moreover, it is arbitrary whether the obtained compound is continuously used for a drying process.

  The thermoplastic resin composition containing the liquid plasticizer of the present invention obtained as a compound as described above can be used as a material for molding a biodegradable resin molded product by an extrusion molding method. As the extrusion molding apparatus, any of extrusion molding apparatuses such as generally used injection molding apparatuses, T-die apparatuses, and inflation apparatuses can be used. The thermoplastic resin composition of the present invention has a composition in which the liquid plasticizer is sufficiently absorbed by the inorganic filler, and the inorganic filler that has absorbed the liquid plasticizer adheres to the surface of the pellet-shaped thermoplastic resin. Since the liquid plasticizer and the inorganic filler are kneaded and dispersed in the resin composition, when this is put into the hopper of an extrusion molding apparatus, the thermoplasticity In the resin composition, pellets do not adhere to each other and clog the exit portion of the hopper, and a part of the liquid plasticizer may be separated from the thermoplastic resin composition and accumulated in the hopper. There is no. Therefore, the extrusion moldability is good.

  In the biodegradable extruded sheet or film of the present invention described above (hereinafter, the sheet or film is generically referred to simply as “sheet”), as described above, each constituent component is well dispersed and uniform. Therefore, there is no possibility of variations in physical properties and shapes of molded products due to unevenness of compound components. In addition, the sheet is made of a biodegradable thermoplastic resin containing polylactic acid, and since a liquid plasticizer is preferably used, it contains a polylactic acid having a very high tensile elasticity with a tensile modulus of 1200 MPa or less. The biodegradable extruded sheet can be provided.

  The tensile elastic modulus described in the biodegradable extruded sheet of the present invention is a sheet having a thickness of 5 mm / min in a normal temperature environment using a test piece having a thickness of 1 mm according to JIS K7113 (plastic tensile test method). It means the tensile elastic modulus measured by pulling in the extrusion direction.

  The tensile modulus of the biodegradable extruded sheet of the present invention is 1200 MPa or less, and can be adjusted by the amount of polylactic acid used, the amount or type of liquid plasticizer and inorganic filler, In particular, even when 100% by weight of polylactic acid is used as the thermoplastic resin, the tensile elastic modulus can be reduced to 550 MPa or less. Further, when the amount of polylactic acid used as the thermoplastic resin is 50% by weight or less, it is possible to provide a sheet having higher flexibility, specifically, very excellent flexibility of 300 MPa or less. Sheet can be provided.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
First, (A) a thermoplastic resin, (B) an inorganic filler, and (C) a liquid plasticizer using the materials and proportions (parts by weight) shown in Table 1 as Example 1, and at the same time in a Henschel mixer at room temperature. The mixture was mixed for 10 minutes at a stirring speed of 350 rpm to prepare Example Mixture 1 in which the constituent materials of the thermoplastic resin composition were stirred and mixed. Example mixture 1 was prepared in such a state that (C) the inorganic filler which absorbed the liquid plasticizer (B) was adhered to the pellet surface of (A) the thermoplastic resin.

Next, the above-mentioned Example mixture 1 was put into the hopper of a biaxial extrusion molding apparatus (hopper outlet inner diameter: 5 cm, feed apparatus: single screw) having a screw diameter of 30 mm, and melt extrusion was performed at a temperature of 200 ° C. and a discharge speed of 10 kg / h. And a pellet-shaped compound pellet was produced, and Example 1 was obtained. Example 1 was produced in a state where (C) an inorganic filler that absorbed a liquid plasticizer (B) was kneaded into a compound pellet.

(Examples 2 to 10)
Example mixtures 2 to 10 were prepared in the same manner as Example mixture 1 using (A) thermoplastic resin, (B) inorganic filler, and (C) liquid plasticizer shown in Table 1 as Examples 2 to 10. Then, compound pellets were prepared in the same manner as in Example 1 except that Example Mixtures 2 to 10 were used.

(Comparative Examples 1-6)
Comparative Examples 1 to 6 were prepared in the same manner as Example Mix 1 using (A) thermoplastic resin, (B) inorganic filler, and (C) liquid plasticizer shown in Table 2 as Comparative Examples 1 to 6. Then, compound pellets were prepared in the same manner as in Example 1 except that Comparative Examples Mixtures 1 to 6 were used, which were referred to as Comparative Examples 1 to 6, respectively.

  The details of (A) thermoplastic resin, (B) inorganic filler, and (C) liquid plasticizer shown in Tables 1 and 2 are as follows.

(A) Thermoplastic resin <PLA> Lacia H400 (polylactic acid: manufactured by Mitsui Chemicals, Inc.)
<PBS> Bionore # 1001 (Polybutylene succinate: Showa Polymer Co., Ltd.)
<PBAT> Ecoflex (Polybutylene adipate terephthalate: manufactured by BASF Japan Ltd.)

(B) Inorganic filler <Kallite KT> Porous calcium carbonate whose particle surface is composed of irregular irregularities (inorganic filler, manufactured by Shiraishi Calcium Co., Ltd., weight average particle diameter 2.3 μm, specific surface area 35 m ² / g, product of weight average particle diameter and specific surface area: 80.5, oil absorption 70 ml / 100 g)
<ALBACAAR 5970> Precipitated calcium carbonate whose particle surface is composed of irregular irregularities (inorganic filler, manufactured by Pfematech Co., Ltd., weight average particle size 1.9 μm, specific surface area 7 m ² / g, weight average particle size And the specific surface area: 13.3, the oil absorption is 50 ml / 100 g, and the particle surface is in the shape of rose petals)
<Vigot 10> Light spherical calcium carbonate having a substantially spherical shape (inorganic filler, manufactured by Shiraishi Kogyo Co., Ltd., weight average particle size 0.17 μm, specific surface area 13.5 m ² / g, product of weight average particle size and specific surface area: 2 .3, Oil absorption 28ml / 100g)
<NS2300> amorphous heavy calcium carbonate (inorganic filler, manufactured by Nitto Flour Chemical Co., Ltd., weight average particle size 0.97 μm, specific surface area 2.3 m ² / g, product of weight average particle size and specific surface area : 2.2, oil absorption 34.5ml / 100g)
In addition, the oil absorption amount of the inorganic filler mentioned above is a value measured by the boiled linseed oil method in JIS K5101.

(C) Liquid plasticizer <Triacetin> Glyceryl triacetate (Liquid plasticizer: manufactured by Daihachi Chemical Industry Co., Ltd.)
<Riquemar PL012> Glyceryl diacetate monolaurate (liquid plasticizer, manufactured by Riken Vitamin Co., Ltd.)

(Evaluation)
In the process of producing each of Examples 1 to 10 and Comparative Examples 1 to 6, the moldability was evaluated as follows. The evaluation results of Examples 1 to 10 are shown in Table 1, and the evaluation results of Comparative Examples 1 to 6 are shown in Table 2, respectively.

(Formability evaluation 1)
The example mixture (or comparative example mixture) was put into a hopper of an extrusion molding apparatus, and the state of being fed into a screw part in the extrusion molding apparatus was evaluated as follows.

○: Example mixture (or comparative example mixture) was smoothly fed from the hopper to the screw part.
(Triangle | delta): A part of example mixture (or comparative example mixture) couple | bonded together and it became the lump shape, and clogging occurred in the hopper exit occasionally.
X: The example mixture (or comparative example mixture) was bound to each other and solidified at the hopper outlet, and the feeding from the hopper to the screw portion was completely stopped, and extrusion molding could not be performed.

(Formability evaluation 2)
The example mixture (or comparative example mixture) put into the hopper was fed into the screw part in the extrusion molding apparatus, and the molten resin pressure at the time of melt extrusion molding was observed and evaluated as follows. In addition, the molten resin pressure shown below is a pressure measured immediately before the molten resin passes through a screen mesh installed at the screw tip (die side) in the extrusion molding apparatus.

○: The molten resin pressure was stable from the start to the end of the process of forming the compound pellets by the extrusion molding apparatus.
X: The molten resin pressure was different at the start and end of the process of molding the compound pellets with the extrusion molding apparatus, or the molten resin pressure during the molding process was not stable.

  From the results of the above molding evaluation 1, in Examples 1 to 10, no self-adhesion of the example mixture occurs, and a part of the liquid plasticizer separates from the example mixture and accumulates in the hopper. There was no inconvenience. As a result, Example Mixtures 1 to 10 were smoothly fed from the hopper to the screw portion in the extrusion molding apparatus. From the above results, in the example mixture, the liquid plasticizer causing stickiness was sufficiently absorbed by the inorganic filler specified by the present invention, and the inorganic filler adhered to the surface of the pellet-shaped thermoplastic resin. However, it was shown that it was put into the hopper and then fed into the screw part without stickiness or liquid separation.

  And in shaping | molding evaluation 2, when all were melt-mixed and extruded in the extrusion molding machine, Examples 1-10 showed the stable molten resin pressure. This is thought to be due to the fact that the example mixture is not sticky, and that there is no unevenness in its composition. Therefore, it is understood that Examples 1-10 which are the obtained compound pellets are high-quality pellets having no composition unevenness.

On the other hand, in the step of molding Comparative Example 1 using Comparative Example Mixture 1 that does not use any inorganic filler, in Molding Evaluation 1, a part of Comparative Example Mixture 1 binds to each other in the hopper and is agglomerated. Thus, clogging was occasionally observed at the hopper outlet, and a part of the liquid plasticizer was separated from the comparative example mixture 1 and accumulated in the lower part of the hopper. This is probably because the liquid plasticizer causes stickiness of the mixture, and the thermoplastic resin and the liquid additive are not mixed well, and a part of them separates to form a liquid pool.
Moreover, as a result of the stickiness of the comparative mixture 1 and part of the mixture adhering to the wall surface of the extrusion molding apparatus or liquid pooling, poor mixing and compositional irregularities occurred, and in Molding Evaluation 2, a stable molten resin in the extrusion molding apparatus. No pressure was indicated.

Comparative Example 2 and Comparative Example 3 are not the inorganic filler specified by the present invention in Comparative Example Mixture 2 or 3 used for the production thereof, and the product of the weight average particle diameter and the specific surface area is much less than 10, and Further, an inorganic filler having an oil absorption of less than 40 ml / 100 g was used. Therefore, in the molding steps of Comparative Example 2 and Comparative Example 3, the liquid plasticizer is not sufficiently absorbed by the inorganic filler, and the Comparative Example mixture charged in the hopper is extremely sticky, and the resins are bound to each other and clay. It was observed that it became a lumpy mass. Then, the hopper outlet was clogged, and the feeding from the hopper to the screw portion was completely stopped.
Moreover, since the comparative example mixture 2 or 3 was not sent into the extrusion molding apparatus, the molding evaluation 2 was not able to be evaluated.

The comparative example 4 used the inorganic filler which satisfy | fills the product of the weight average particle diameter and specific surface area which this invention specifies, and the oil absorption amount in the comparative example mixture 4 used for the preparation. However, the ratio of the ratio of the inorganic filler to the liquid plasticizer specified in the present invention was outside the range of 99: 1 to 50:50, and the ratio of the liquid plasticizer was high. As a result, in the molding process of Comparative Example 4, as in Comparative Examples 2 and 3, the Comparative Example mixture charged in the hopper was extremely sticky, and the resins were bonded together to form a clay-like lump. Was observed. As a result, the hopper outlet was clogged, and the feeding from the hopper to the screw portion was completely stopped.
Moreover, since the comparative example mixture 4 was not sent into the extrusion molding apparatus, the molding evaluation 2 could not be evaluated.

In Comparative Example 5 and Comparative Example 6, the inorganic filler satisfying the conditions of the product of the weight average particle diameter and specific surface area specified by the present invention and the oil absorption amount in Comparative Example Mixture 5 or 6 used for the production thereof. Used. However, the blending ratio of the liquid plasticizer exceeded 50 parts by weight with respect to 100 parts by weight of polylactic acid used as the thermoplastic resin. As a result, in molding evaluation 1, the comparative mixture 5 or 6 charged into the hopper is easily clogged at the hopper outlet, and a part of the inorganic filler that has absorbed the liquid plasticizer is separated from the comparative mixture 5 or 6. A state of accumulation at the bottom of the hopper was observed.
As a result of clogging at the hopper outlet and partial separation of the inorganic filler that has absorbed the liquid plasticizer, mixing failure and composition unevenness occur, and in molding evaluation 2, the extrusion pressure of the resin composition is from the beginning to the end of extrusion. Was not stable.

(Measurement of tensile modulus of thermoplastic resin sheet)
Next, the compound pellets of Examples 1 to 10, Comparative Examples 1 to 6, and Reference Example 1 (made in the same manner as in Example 1 except that the inorganic filler and the liquid plasticizer were not used) were used. Each of the above compound pellets was put into a hopper of a T-die extruder (screw diameter: 40 mm, die width: 40 cm), and melt extrusion was performed at an extrusion temperature of 180 ° C. and a discharge speed of 10 kg / h to form a sheet having a thickness of 1 mm. The obtained sheets were referred to as Example sheets 1 to 10, Comparative example sheets 1 to 6, and Reference example sheet 1, respectively.

  Next, using Example Sheets 1 to 10 obtained above, Comparative Example Sheets 1 to 6, and Reference Example Sheet 1, tensile modulus was measured according to JIS K7113 (plastic tensile test method). The measurement results are shown in Table 1 for Example Sheets 1 to 10, and in Table 2 for Comparative Example Sheets 1 to 6 and Reference Example Sheet 1.

It is a graph which shows the correlation of the reciprocal number of the average particle diameter of a calcium carbonate particle, and a surface area.

Explanation of symbols

Black diamond plot The measurement results of spherical general-purpose calcium carbonate having no irregularities on the surface and almost no pores are shown.
Open diamond plot Shows the measurement results of special calcium carbonate.

Claims (5)

(A) a thermoplastic resin;
(B) The weight average particle diameter is 0.1 μm or more and 10 μm or less, the product of the weight average particle diameter (μm) and the specific surface area (m ² / g) is 10 or more, and the boiled linseed oil absorption is 40 ml / 100 g or more. An inorganic filler in which the particle surface is composed of irregular irregularities and is in the form of rose petals or burrs ;
(C) a liquid plasticizer;
Including
The (A) is a polylactic acid of 10% by weight to 100% by weight, a biodegradable aliphatic polyester of 0% by weight to 90% by weight, and a biodegradable aliphatic aromatic polyester of 0% by weight to 90% by weight. It is composed by the mixing ratio,
The ratio of parts by weight of (B) and (C) is (B) :( C) = 99: 1 to 50:50.
And
A thermoplastic resin composition containing a liquid plasticizer, wherein the blending ratio of (C) is 5 to 50 parts by weight with respect to 100 parts by weight of polylactic acid in (A). (A) is composed of polylactic acid and aliphatic polyester and / or aliphatic aromatic polyester,
The polylactic acid is composed of 10 wt% to 90 wt%, aliphatic polyester 10 wt% to 90 wt%, and aliphatic aromatic polyester 10 wt% to 90 wt%. A thermoplastic resin composition comprising the liquid plasticizer according to Item 1. The thermoplastic resin composition containing a liquid plasticizer according to claim 1 or 2, wherein the inorganic filler is calcium carbonate . A liquid plasticizer characterized by producing a thermoplastic resin composition by simultaneously mixing (A), (B) and (C) described in any one of claims 1 to 3. The manufacturing method of the thermoplastic resin composition to contain . A biodegradable extruded sheet or film having a tensile elastic modulus of 1200 MPa or less, formed using the resin composition containing the liquid plasticizer according to any one of claims 1 to 3.

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