JP2005042283A - Method for producing aliphatic polyester composition, pulp used for the same, and cellulosic fiber, and method for microfibrillating the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a highly rigid and strong fiber/biodegradable resin composite material by uniformly and minutely dispersing a fiber component into a resin component by conventional means without requiring pretreatment of the resin component. <P>SOLUTION: The aliphatic polyester composition is produced by melting and kneading 1-99.9 pts.wt. resin component comprising 1-100 wt.% aliphatic polyester (A) and 99-0 wt.% polylactic acid (B), and 99-0.1 pt.wt fiber component comprising pretreated pulp by injuring primary walls and secondary outer walls and/or cellulose-based fiber (C) in the presence of a cellulose noncrystalline region-swelling agent (D). The fiber component is microfibrillated during melting and kneading and uniformly and minutely dispersed in the resin component. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is used in fields such as household goods and packaging materials, and after being discarded, it is biologically decomposed by microorganisms in a natural environment such as soil, and finally completely decomposed into carbon dioxide and water. An environmentally friendly biodegradable aliphatic polyester composition, a method for industrially advantageously producing a high-strength, high-rigidity aliphatic polyester composition, pretreated pulp and / or The present invention relates to a cellulosic fiber and a method for microfibrillation thereof.

  As high-rigidity and high-strength biodegradable composite materials, composite materials of plant fibers and biodegradable resins have been studied. For example, in JP-A Nos. 06-345944 and 2002-292608, a biodegradable composite material having excellent rigidity can be obtained by dispersing pulp or cellulosic fibers in a biodegradable resin. It describes what you can do.

Incidentally, in a composite material composed of a thermoplastic resin and a fiber, it is known that characteristics such as mechanical strength are controlled by the aspect ratio of the fiber dispersed in the material. In order to obtain a high-aspect-ratio cellulosic fiber, Japanese Patent Publication No. 48-6641 and Japanese Patent Publication No. 50-38720 disclose a microfibril-forming method using the hydrophilicity characteristic of pulp or cellulosic fiber. The microfibril cellulose fibers are obtained by highly repeatedly grinding or beating the pulp with a refiner, a homogenizer or the like.
Japanese Patent Laid-Open No. 06-345944 JP 2002-292608 A Japanese Patent Publication No. 48-6641 Japanese Patent Publication No. 50-38720

  It is difficult to finely disperse pulp or cellulosic fibers in a biodegradable resin. In order to uniformly disperse these in a biodegradable resin, the biodegradable resin raw material is pulverized or finely fibered in advance. It is necessary to make it. That is, without making the biodegradable resin into a fine powder or fine fiber beforehand, a composite material in which pulp or cellulosic fibers are finely dispersed cannot be obtained. A complicated pretreatment of pulverizing or finely forming the biodegradable resin composite material is always required.

  In addition, the production of such a plant fiber / biodegradable resin composite material requires a complicated process such as a wet kneading process, a wet compression molding process, and a subsequent drying process. The apparatus and the molding process cannot be applied. As a result, much labor energy is consumed, and the resulting composite material is expensive, so that there is a problem that it is difficult to put into practical use.

  Therefore, the present invention does not require complicated pretreatment of the biodegradable resin and fine fiberization of the pulp, and by adopting a general-purpose kneading means, the fiber component is uniformly finely dispersed in the resin component to obtain a microfiber. It is an object of the present invention to provide a method for producing a high-strength and high-rigidity biodegradable aliphatic polyester composition as fibrillated cellulose fibers, and pulp and cellulosic fibers used therefor, and a method for microfibrillation thereof.

  The method for producing an aliphatic polyester composition of the present invention comprises (a) an aliphatic diol and (b) an aliphatic polyester (A) obtained by reacting an aliphatic dicarboxylic acid and / or a derivative thereof (1 to 100 weights). %, From 1 to 99.9 parts by weight of a resin component consisting of 99% to 0% by weight of polylactic acid (B), pretreated pulp and / or cellulosic fibers (C) that have damaged the primary wall and the secondary wall outer layer. 99 to 0.1 parts by weight of the resulting fiber component is melt kneaded in the presence of the cellulose amorphous region swelling agent (D) (however, the total of the resin component and the fiber component is 100 parts by weight) And).

  In the present invention, “aliphatic” means “aliphatic” in a broad sense including “alicyclic”. The aliphatic polyester (A) reacts (a) an aliphatic diol, (b) an aliphatic dicarboxylic acid and / or a derivative thereof, and (c) a bifunctional aliphatic hydroxycarboxylic acid and / or a derivative thereof. It may be obtained.

  As a result of intensive studies to solve the above problems, the present inventors have used a resin component obtained by pretreating pulp and / or cellulosic fibers and damaging the outer wall of the primary wall and the secondary wall. Without the need for pre-treatment of the components, the fiber component can be uniformly and finely dispersed in the resin component by a general-purpose melt-kneading method to obtain a microfibril-like cellulose fiber. The present inventors have found that a high-strength composite material can be obtained and completed the present invention.

  As described above, in the conventional plant fiber / biodegradable resin composite member, the biodegradable resin is pulverized or made into fine fibers in advance for uniform fine dispersion of the fiber component in the biodegradable resin. The pretreatment for this required a lot of labor. In addition, complicated operations are required for kneading, molding, and subsequent drying.

  On the other hand, in order to uniformly disperse the fiber component in the thermoplastic resin, the fiber component is microfibrillated by highly repeatedly grinding or beating the fiber component. In addition, complicated operations in the presence of moisture and a great amount of labor are required, and the microfibrillated fibers are in a slurry state, which makes it difficult to handle and is not always easy to supply to the kneader. Absent. In addition, the fibers that have been microfibrillated in advance tend to form frogs (solids) during kneading with the resin, and are not likely to become high aspect ratio fibers.

  The present inventors do not spend a great deal of effort on such pretreatment operations, only simple pretreatment, and without the need for special kneading means. As a result of intensive investigations on a method for uniformly finely dispersing fiber components in the pulp, and / or cellulosic fibers that have been subjected to a simple pretreatment that damages the outer wall of the primary wall and the secondary wall, the presence of a cellulose amorphous region swelling agent It has been found that by melting and kneading the resin component below, the fiber component can be defibrated and microfibrillated during the melt kneading and can be uniformly finely dispersed in the resin component. That is, pulp and / or cellulosic fibers whose primary wall and secondary wall outer layer have been damaged by pretreatment are easily defibrated during melt-kneading, and are easily defibrated and uniformly finely dispersed in the molten resin. . Moreover, the pulp and / or cellulosic fibers in which only the primary wall and the secondary wall outer layer are damaged are easy to handle and can be kneaded smoothly.

  The pulp and cellulosic fiber of the present invention are suitably used in, for example, such a method for producing an aliphatic polyester composition, and are characterized by damaging the primary wall and the secondary wall outer layer.

  Moreover, the microfibrillation method of the pulp and / or cellulosic fiber of the present invention comprises a pulp and / or cellulosic fiber (C) formed by damaging the outer wall of the primary wall and the secondary wall with a cellulose amorphous region swelling agent (D The fiber component is defibrated by kneading in the presence of).

  According to the method for producing an aliphatic polyester composition of the present invention, the resin component is obtained by general-purpose kneading means only by performing simple pretreatment on the fiber component without requiring a complicated pretreatment step of the resin component. A fiber component can be uniformly and finely dispersed therein to produce a highly rigid and high strength fiber / biodegradable resin composite material.

  According to the present invention, a general-purpose thermoplastic resin kneading means and a molding means can be used to produce a high-strength, high-rigidity fiber / biodegradable resin composite molded product. It can be applied to extrusion molding equipment such as injection molding, film, and sheet, so that production efficiency can be improved and production cost can be reduced.

  Hereinafter, embodiments of the method for producing the aliphatic polyester composition of the present invention, pulp and cellulosic fibers used therefor, and a method for microfibrillation thereof will be described in detail.

[Aliphatic polyester (A)]
The aliphatic polyester (A) used in the present invention comprises (a) an aliphatic diol, (b) an aliphatic dicarboxylic acid and / or a functional derivative thereof, and (c) if necessary. It is obtained by reacting a bifunctional aliphatic hydroxycarboxylic acid and / or a derivative thereof, and preferably obtained by carrying out this reaction in the presence of a germanium catalyst.

<(A) Aliphatic diol>
The (a) aliphatic diol (including alicyclic diol) used in the present invention is a compound having two hydroxyl groups, and a preferred specific example thereof is represented by the following general formula (I).

HO—R ¹ —OH (I)

In the general formula (I), R ¹ is a divalent aliphatic hydrocarbon group, preferably an aliphatic hydrocarbon group having 2 to 11 carbon atoms, particularly preferably 2 to 6 carbon atoms. R ¹ may have a branched chain or a cycloalkylene group. R ¹ is preferably — (CH ₂ ) n — (where n is an integer of 2 to 11, preferably an integer of 2 to 6).

  The (a) aliphatic diol that can be used in the present invention is not particularly limited, and specific examples thereof include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, , 6-hexanediol, 1,4-cyclohexanediol, 1,6-cyclohexanedimethanol and the like. These may be used alone or as a mixture of two or more.

  In view of the physical properties of the resulting aliphatic polyester (A), the (a) aliphatic diol is particularly preferably 1,4-butanediol.

<(B) Aliphatic dicarboxylic acid and / or derivative thereof>
(B) Aliphatic dicarboxylic acids (including alicyclic dicarboxylic acids) and / or derivatives thereof used in the present invention are those represented by the following general formula (II), or those having 1 to 4 carbon atoms lower And alkyl esters or anhydrides thereof.

^{HOOC-R 2 -COOH ... (II} )

In general formula (II), R ² is a direct bond or a divalent aliphatic hydrocarbon group, preferably a divalent aliphatic hydrocarbon group having 2 to 11 carbon atoms, particularly preferably 2 to 6 carbon atoms. . R ² may have a branched chain or a cycloalkylene group. R ² is preferably — (CH ₂ ) m — (where m represents an integer of 0 or 1 to 11, preferably 0 or an integer of 1 to 6).

  Preferable specific examples of the aliphatic dicarboxylic acid include oxalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, suberic acid, dodecanedioic acid and the like, and functional derivatives thereof include these acid anhydrides. It is done.

  These may be used alone or as a mixture of two or more. That is, you may use together within each group and / or between each group.

  From the viewpoint of physical properties of the resulting aliphatic polyester (A), (b) the aliphatic dicarboxylic acid and / or its derivative is preferably succinic acid or succinic anhydride, or a mixture of these with adipic acid. .

<(C) Bifunctional aliphatic hydroxycarboxylic acid and / or derivative thereof>
(C) The bifunctional aliphatic hydroxycarboxylic acid (including alicyclic hydroxycarboxylic acid) and / or its derivative bifunctional aliphatic hydroxycarboxylic acid usable in the present invention includes one hydroxyl group in the molecule. Although it will not specifically limit if it has one carboxylic acid group, The aliphatic hydroxycarboxylic acid corresponding to the aliphatic hydroxycarboxylic acid unit of the following general formula (III) is suitable, As a derivative, Those lower alkyl esters having 1 to 4 carbon atoms or their intramolecular esters are preferred.

^{HO-R 3 -COOH ... (III} )

In the general formula (III), R ³ is a divalent aliphatic hydrocarbon group, preferably a C 1-11 carbon atom, particularly preferably a C 1-6 divalent aliphatic hydrocarbon group. R ³ may be a cycloalkylene group, but is preferably a chain hydrocarbon group. The “chain” includes not only “linear” but also “branched”.

  (C) The bifunctional aliphatic hydroxycarboxylic acid and / or derivative thereof is more preferably one in which a hydroxyl group and a carboxyl group are bonded to one carbon atom and represented by the following general formula (IV) Is preferred. The use of a bifunctional aliphatic hydroxycarboxylic acid represented by the following general formula (IV) or a derivative thereof is particularly preferable because the polymerization rate increases.

（一般式（IV）中、ａは０又は１以上の整数、好ましくは０又は１〜１０、より好ましくは０又は１〜５の整数である。）

(In general formula (IV), a is 0 or an integer of 1 or more, preferably 0 or 1 to 10, more preferably 0 or an integer of 1 to 5.)

  Specific examples of the bifunctional aliphatic hydroxycarboxylic acid include lactic acid, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2- Examples include those obtained by ring-opening lactones such as hydroxy-3-methylbutyric acid, 2-methyllactic acid, 2-hydroxycaproic acid, or caprolactone. These may be used alone or as a mixture of two or more. In addition, when an optical isomer exists in these, any of D-form, L-form, or a racemic form may be sufficient, and a solid, liquid, or aqueous solution may be sufficient as a shape. In particular, lactic acid and an aqueous solution thereof are particularly preferred since the increase in the polymerization rate during use is particularly remarkable and is easily available. Lactic acid is generally commercially available in 50%, 70%, and 90% aqueous solutions, and is easily available. Moreover, the compatibility between the aliphatic polyester (A) and the polylactic acid (B) is enhanced by using lactic acid.

<Aliphatic polyester (A) and production thereof>
The aliphatic polyester (A) used in the present invention comprises the above components (a), (b) and, if necessary, the component (c) under the conditions for forming the polyester, preferably in the presence of a catalyst comprising a germanium compound. Manufactured by reacting method.

  (A) The amount of the aliphatic diol used is substantially equimolar to (b) the aliphatic dicarboxylic acid and / or its derivative, but it is distilled during the esterification reaction in the actual production process. Therefore, (a) the aliphatic diol is used in an excess of 1 to 50 mol, preferably 5 to 30 mol, per 100 mol of (b) the aliphatic dicarboxylic acid and / or its derivative.

  When the component (c) is used, the amount of the (c) bifunctional aliphatic hydroxycarboxylic acid and / or derivative thereof used is generally 0.04 to 100 mol per 100 mol of the (b) aliphatic dicarboxylic acid and / or derivative thereof. 60 mol, preferably 1 to 20 mol, more preferably 3 to 10 mol. (C) When the bifunctional aliphatic oxycarboxylic acid and / or its polymer is less than this range, the effect of improving the polymerization reactivity due to the use thereof is less likely to appear, making it difficult to obtain a high molecular weight aliphatic polyester, If it exceeds this range, the heat resistance and strength will be insufficient.

  (C) The addition time of the bifunctional aliphatic hydroxycarboxylic acid and / or derivative thereof is not particularly limited as long as it is before the polyester formation reaction. For example, the catalyst is used in advance as the catalyst (c) aliphatic hydroxycarboxylic acid and / or derivative thereof. A method in which the raw material is added in the solution or in the esterification reaction in a state dissolved in a solution, or a method in which a catalyst is added at the same time as the raw material is added, is preferable.

  The production of the aliphatic polyester (A) used in the present invention is generally carried out in the presence of a germanium compound-based catalyst.

  The germanium compound-based catalyst used may be composed of only one kind of germanium compound, may be composed of two or more kinds, and is known as one or more kinds of germanium compounds. It can also be used in combination with any catalyst that can be used for the production of polyester, for example, a metal compound catalyst soluble in the reaction system such as titanium, antimony, tin, magnesium, zinc, calcium and the like. As the germanium compound, for example, an organic germanium compound such as tetraalkoxygermanium, or an inorganic germanium compound such as germanium oxide or germanium chloride is particularly preferable. In view of price and availability, germanium oxide, tetraethoxygermanium, tetrabutoxygermanium, and the like are particularly preferable. The amount of these catalysts used is generally 0.001 to 3% by weight, more preferably 0.005 to 1.5% by weight, based on the amount of monomers used, that is, the total amount of components (a) to (c). is there. The catalyst addition time is not particularly limited as long as it is before the production of the polyester, but it may be added when the raw materials are charged, or may be added at the start of pressure reduction. As described above, (c) the bifunctional aliphatic hydroxycarboxylic acid and / or its derivative is added at the same time as charging the raw materials, or (c) the catalyst is added to the bifunctional aliphatic hydroxycarboxylic acid and / or its derivative or its aqueous solution. It is particularly preferable to add after dissolving.

Conditions such as temperature, time, and pressure when producing the aliphatic polyester (A) are not particularly limited as long as the target aliphatic polyester (A) is obtained, but the temperature is 150 to 260 ° C. Preferably it is 180-230 degreeC, superposition | polymerization time is 1 hour or more, Preferably it is 2-15 hours, The pressure reduction degree at the time of a polycondensation reaction is 1.33 * 10 < ³ > Pa or less, More preferably, it is 0.27 * 10 < ³ > Pa or less. It is preferable to select from a range.

  The aliphatic polyester (A) thus obtained has the (a) component and the (b) component as main polyester members, and if the raw materials are blended at the blending ratio as described above in the production thereof, In general, the molar ratio of (a) the aliphatic diol unit and (b) the aliphatic dicarboxylic acid (functional derivative) unit is substantially equal, and the moles of all constituent components of the aliphatic polyester copolymer When the number is 100 mol, (c) the bifunctional aliphatic hydroxycarboxylic acid unit is preferably 0.02 to 30 mol. In particular, when the (c) bifunctional aliphatic hydroxycarboxylic acid component is lactic acid, the compatibility between the aliphatic polyester (A) and the polylactic acid (B) is improved by introducing the component (c) within such a range. Is highly preferred.

  The number average molecular weight Mn of the aliphatic polyester (A) used in the present invention is generally 10,000 to 300,000, and usually 30,000 to 300,000.

  In addition, (d) other copolymerization components can be introduce | transduced to the aliphatic polyester (A) used for this invention, unless the effect is impaired. (D) Addition of trifunctional or higher polyhydric hydroxycarboxylic acid, polyhydric carboxylic acid, polyhydric alcohol and the like as other copolymerization components is preferable because the melt viscosity can be increased. Specific examples of such components include malic acid, trimethylolpropane, glycerin, pentaerythritol, trimellitic acid and the like. From the physical properties of the resulting aliphatic polyester (A), malic acid, Trimethylolpropane, glycerin and the like are particularly preferable. The proportion of such other copolymerization component (d) is preferably 0.001 to 3 moles when the number of moles of all components of the aliphatic polyester copolymer is 100 moles.

[Polylactic acid (B)]
The polylactic acid (B) used in the present invention is not particularly limited, but the number average molecular weight necessary for having sufficient strength is 30,000 or more, preferably 100,000 or more. The upper limit of the number average molecular weight of polylactic acid (B) is not particularly limited, but is usually 1,000,000 or less, preferably 500,000 or less. From the physical properties of the resulting polylactic acid (B), the molar ratio of the L-form and D-form constituting the polylactic acid (B) can be used in all compositions where L / D is 100/0 to 0/100. In order to obtain a high product, the L form is preferably 95 mol% or more. The production method of polylactic acid (B) is not particularly limited, and examples thereof include a ring-opening polymerization method via lactide or a direct polycondensation method of lactic acid.

[Pretreated pulp and / or cellulosic fiber (C) with damaged primary wall and secondary wall outer layer]
<Pulp and / or cellulosic fiber>
Pulp and / or cellulosic fibers used in the present invention include kraft pulp, chemically treated pulp of wood such as sulfite pulp, regenerated pulp regenerated from waste paper, artificial cellulose fiber, bacterial cellulose fiber by acetic acid bacteria, Examples thereof include cellulose fibers derived from animals such as sea squirts, and those obtained by chemically modifying these, and these may be used alone or in combination of two or more. Among these, from the viewpoint of cost and global environment, pulp obtained from plant-derived wood, waste paper or the like is preferable. In addition, there exist acetylation, cyanoethylation etc. as a typical chemical modification method of a pulp and / or a cellulose fiber.

<Pretreatment of pulp and / or cellulosic fibers>
As shown in FIG. 2, the pulp and the cellulosic fiber have a laminated structure including a primary wall 1, a secondary wall outer layer 2, a secondary wall middle layer 3, and a secondary wall inner layer 4. In FIG. 1, fine lines in each layer indicate the orientation direction of cellulose microfibrils. The primary wall 1 of the pulp and the outer layer 2 of the secondary wall function as a sheath-shaped shell of the inner layers 3 and 4 in the secondary wall that occupies 70 to 90% of the laminated structure, and the inner layer 3 in the secondary wall. 4 is firmly bound.

  In conventional thermoplastic resin-based composite materials, in order to completely unravel the sheath-like shell and make the cellulose fibers of the aggregate into microfibrils, repeated grinding and beating with dozens of refiners and high-pressure homogenizers are performed. However, in the present invention, the above-described pulp and / or cellulosic fiber is subjected to a mild pretreatment that damages the outer wall of the primary wall and the secondary wall, so that the outermost sheath is easily broken down. Is used.

  Examples of the pretreatment method include known refiner treatment, medium stirring mill treatment, vibration mill treatment, stone mill treatment, and the like, but refiner treatment is preferred.

  In addition, although the semichemical pulp which processed the pulp mechanically with the refiner, the grinder, etc. is generally provided, if the water retention rate mentioned later is satisfy | filled, this semichemical pulp can also be utilized as a pre-processing pulp.

  The condition of scratches on the primary wall and the secondary wall outer layer due to such pretreatment is grasped by observing the morphology of the pretreated pulp and / or cellulosic fibers with a microscope and the water retention rate of the pretreated pulp and / or cellulosic fibers. be able to. The water retention is a weight percentage of (water content / solid content) × 100% after a slurry having a solid content of 2% by weight is treated with a centrifugal separator at 1000 G for 15 minutes, and pulp and cellulosic fibers without pretreatment The water retention rate is usually 100 to 120%. In the present invention, it is preferable to use pulp and / or cellulosic fibers having a water retention rate of 150 to 600%, particularly 200 to 400% by pretreatment.

  The pretreated pulp and / or cellulosic fiber (C) is an aggregate of cellulose fibers having an average diameter of several tens of μm to several tens of μm. For example, melt kneading with a resin component by a twin screw extruder described later Accordingly, microfibrillated cellulose having an average diameter of several μm to 0.005 μm and a length / diameter ratio (aspect ratio) of 10 or more, for example, 20 to 200, is branched (defibrated) from the aggregate of cellulose fibers. In the resin component, it is finely dispersed uniformly as if it were a spider web.

  Further, the pulp and / or cellulosic fibers formed by damaging the primary wall and the secondary wall outer layer are kneaded without a resin component in the presence of a cellulose amorphous region swelling agent (D) described later, whereby the fiber component is mixed. It can be fibrillated and microfibrillated, and the pulp and / or cellulosic fibers thus obtained can be used effectively not only for aliphatic polyester compositions but also for various applications.

[Cellulose amorphous region swelling agent (D)]
The cellulose amorphous region swelling agent (D) used in the present invention is a low molecular compound having hydrogen bonding ability with cellulose fibers, and is a cellulose fiber aggregate or a pretreated pulp and / or cellulosic fiber (C). It is a compound that can be impregnated and diffused into the amorphous region of cellulose fiber.

  Specific examples of the cellulose amorphous region swelling agent (D) include water, ethylene glycol, butylene glycol, methyl alcohol, ethyl alcohol, and the like, and water, ethylene glycol, and methyl alcohol are preferable. These cellulose amorphous region swelling agents (D) may be used alone or in combination of two or more.

[Aliphatic polyester composition]
<Formulation of aliphatic polyester composition>
In the present invention, the blending ratio of the aliphatic polyester (A), the polylactic acid (B) blended as necessary, the pretreated pulp and / or the cellulose fiber (C) is aliphatic polyester (A): 100-1 % By weight and polylactic acid (B): 99 to 0.1 weight of pretreated pulp and / or cellulosic fiber (D) with respect to 1 to 99.9 parts by weight of resin component comprising a mixture of 0 to 99 weight% Part.

  The aliphatic polyester (A) is inferior in rigidity and heat resistance to the polylactic acid (B), but preferably has a fine dispersibility of the pretreated pulp and / or cellulosic fiber (C). The polylactic acid (B) is 0 to 60% by weight with respect to 100 to 40% by weight of the aliphatic polyester (A), and more preferably the polylactic acid (B) is 0 to 40% with respect to 100 to 60% by weight of the aliphatic polyester (A). % By weight. The form of the aliphatic polyester (A) and polylactic acid (B) may be granular, powdery, or fibrous, but is preferably granular from the viewpoint of operability.

  The ratio of the fiber component (pretreated pulp and / or cellulosic fiber (C)) to 1 to 99.9 parts by weight of the resin component (total of aliphatic polyester (A) and polylactic acid (B)) is 99 to 0.00. 1 part by weight. For a high-rigidity, high-strength composite material, it is desirable to blend a large amount of fiber component. However, in this case, the flowability at the time of molding is lowered, which is a problem. A preferable blending ratio is 95 to 3 parts by weight of the fiber component with respect to 5 to 97 parts by weight of the resin component, more preferably 65 to 5 parts by weight of the fiber component with respect to 35 to 95 parts by weight of the resin component (however, 100 parts by weight in total with the fiber components).

  In addition, in the aliphatic polyester composition by the manufacturing method of this invention, unless the effect of this invention is impaired, aliphatic polyester (A), polylactic acid (B), a pre-processing pulp, and / or a cellulose type as needed. It goes without saying that components other than the fiber (C), for example, lubricants, waxes, colorants, stabilizers, and other various additives may be blended.

  The cellulose amorphous region swelling agent (D) used in the melt-kneading may be used in a fiber component, that is, the pretreated pulp and / or cellulosic fiber (C) in an amount equal to or higher than the water retention rate of the fiber component. From the refinement | purification effect in the dispersion | distribution process of this, and subsequent separability, it is preferable that it is 100 to 600 weight% of the pretreatment pulp and / or cellulosic fiber (C), especially 200 to 500 weight%.

<Manufacture of aliphatic polyester composition (melt kneading)>
In the present invention, the fiber component is melted and kneaded by using a twin screw extruder, preferably in the presence of the cellulose amorphous region swelling agent (D), so that the fiber component is defibrated and the resin component An aliphatic polyester composition is produced by uniformly finely dispersing fiber components.

  Here, the twin screw extruder used is an apparatus used for mixing, plasticizing, and extruding general-purpose thermoplastic resins, and the rotation direction of the two screws may be either different or same direction. Screw engagement includes a complete engagement type, an incomplete engagement type, and a non-engagement type, but a complete engagement type is preferable from the viewpoint of dispersibility of fiber components. The screw length / screw diameter ratio may be 20 to 70. Specific examples of the twin screw extruder include “TEX” manufactured by Nippon Steel Works, “TEM” manufactured by Toshiba Machine Co., Ltd., and “ZSK” manufactured by Krupp Weller.

  The melt-kneading according to the present invention is preferably carried out by using such a twin-screw extruder, for example, through the following steps (1) or (2) by combining the screw configurations.

  (1) A resin component, a fiber component and a cellulose amorphous region swelling agent are supplied to a twin screw extruder, and the fiber component is defibrated into the resin component in the presence of the cellulose amorphous region swelling agent in the twin screw extruder. A fibrillation / dispersion step to disperse, a melt / dispersion step to melt the resin component and further defibrate and finely disperse the fiber component in the molten resin component, and then separate the cellulose amorphous region swelling agent. Cellulose amorphous region swelling agent separation and extrusion process for extruding the kneaded product.

  In this case, the temperature of the defibrating and dispersing step is preferably 30 to 90 ° C., and the temperature of the melting / dispersing step is preferably 120 to 200 ° C. The extrusion process preferably has a temperature of 120 to 200 ° C. Further, the number of screw rotations is preferably in the range of 50 to 400 rpm in all steps, and in order to prevent hydrolysis of the aliphatic polyester (A) due to long-term residence, the smaller screw length / screw diameter ratio is required. Is preferable, and 25-50 are preferable.

  (2) Supplying the resin component to the twin screw extruder and melting the resin component in the twin screw extruder, and then pressurizing the mixture of the fiber component and the cellulose amorphous region swelling agent to the twin screw extruder A melting, defibrating, and dispersing step in which the fiber component is defibrated and finely dispersed in the resin component in the presence of the cellulose amorphous region swelling agent, and then the cellulose amorphous region swelling agent is separated and kneaded. Cellulose amorphous region swelling agent separation / extrusion process.

  In this case, the melting step is preferably performed at a temperature of 120 to 200 ° C., and the melting, defibrating and dispersing step is preferably performed at a temperature of 120 to 180 ° C. The extrusion process preferably has a temperature of 120 to 200 ° C. and a pressure of atmospheric pressure to vacuum. Moreover, it is preferable that a screw rotation speed is the range of 50-400 rpm in all the processes. In the melting / defibration / dispersing step, the mixture of the cellulose amorphous region swelling agent (D) and the fiber component is injected into the molten resin component at a pressure of atmospheric pressure to several MPa using a pump. In addition, it is preferable to further perform melting, defibration, and fine dispersion without separating the cellulose amorphous region swelling agent (D). In this case, the screw length / screw diameter ratio is preferably 30 to 70.

  In any of the above methods (1) and (2), the cellulose amorphous region swelling agent (D) may be injected into the twin-screw extruder, premixed with the fiber component, and supplied in a liquid pump. If necessary, the cellulose amorphous region swelling agent (D) may be supplied alone in a liquid state. In addition, in order to shorten the fiber component, the melt-kneading step can be used as a pressurizing condition to prevent transpiration of the cellulose amorphous region swelling agent (D). Further, if necessary, the cellulose amorphous region swelling agent (D) can be added to the resin component melting step by a pressure pump. After melt-kneading, the cellulose amorphous region swelling agent (D) can be separated by releasing the pressure and further reducing the pressure.

  Thus, the extruded and granulated aliphatic polyester composition does not require a drying step, and can be subjected to a molding process only by preliminary drying for separation of water adhering to the surface before the molding process essential for the polyester resin. it can.

  The characteristics of the resulting aliphatic polyester composition, that is, the composite material in which the fiber component is uniformly and finely dispersed in the resin component largely depend on the form of the fiber component dispersed in the resin component, and It is preferable to form microfibrils rather than aggregates. In the present invention, as described above, when the resin component and the fiber component are melt-kneaded in the presence of the cellulose amorphous region swelling agent (D), preferably using a twin screw extruder, an aliphatic resin component Polyester (A) and polylactic acid (B) can be mixed and kneaded as a kneading medium, and the fiber component can be defibrated and uniformly finely dispersed in the resin component under good mixing and kneading properties. In the melt-kneading step, the cellulose amorphous region swelling agent (D) reduces the cohesive force between the cellulose microfibrils, facilitates the fibrillation of the cellulose fiber aggregate, It has the function of preventing aggregation of the microfibrillated cellulose that has been fibrillated, and has the effect of improving uniform fine dispersibility. However, it is difficult to completely microfibrillate an aggregate of cellulose fibers, and the fiber component in the aliphatic polyester composition produced according to the present invention includes a microfiber fibrillated from the aggregate of cellulose fibers. Not only fibrillated cellulose but also aggregates of cellulose fibers exist.

<Molding method of aliphatic polyester composition>
As a method for molding the aliphatic polyester composition produced by the method of the present invention, any method similar to the method for molding a normal thermoplastic resin composition can be applied. Specifically, injection molding, extrusion molding, hollow molding, foam molding and the like can be employed.

  Since the aliphatic polyester composition according to the present invention has sufficient rigidity and mechanical strength and can be subjected to various molding processes such as extrusion molding and injection molding, it can be used in a wide range of applications such as household goods and various packaging materials. It can be used suitably for a molded product, and after use and disposal, it is biodegraded, which is effective for reducing the amount of waste and protecting the environment.

  EXAMPLES Specific examples of the present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to these examples unless it exceeds the gist.

The characteristic values in the following examples are measured by the following method.
(1) Number average molecular weight (Mn)
It measured by the gel permeation chromatography (GPC) method. The sample was dissolved in chloroform and measured by polystyrene conversion using a GPC apparatus (manufactured by Tosoh Corporation, HLC-8120 type). The column used was TSKgel SuperHM-M (manufactured by Tosoh Corporation).
(2) Flowability: Melt flow ratio (MFR)
Measurement was performed at 190 ° C. under a load of 2.16 kg in accordance with JIS K7210.
(3) Three-point bending rigidity and breaking strength The injection molded product was conditioned at 23 ° C., 50% relative humidity and 24 hours, and the three-point bending rigidity and breaking strength were measured according to JIS K 7203.
(4) Appearance of injection-molded product The injection-molded product was visually observed to evaluate the uniformity depending on the presence or absence of fiber aggregates.
(5) Photo of the form of the fiber In the case of pulp only: A part of the mixture of pretreated pulp or untreated pulp and water is freeze-dried
The images were taken with a scanning electron microscope.
In composition: Dissolve the composition in chloroform and add distilled water to pulp or fiber
Is extracted to the water layer side, and a part of the extract is lyophilized and placed in a scanning electron microscope.
I took a picture.

  As the aliphatic polyester (A), the aliphatic polyester (A) produced in Production Example 1 below was used.

Production Example 1 Production of Aliphatic Polyester (A) In a reaction vessel having a capacity of 300 ml equipped with a stirrer, a nitrogen introduction tube, a heating device, a thermometer, and an auxiliary agent addition port, 118.1 g of succinic acid (b), 4-butanediol (a) 99.1 g, 6.3 g of a 90% lactic acid (c) aqueous solution in which 1% by weight of germanium oxide was dissolved in advance (6.3 mol with respect to 100 mol of succinic acid), and malic acid (d ) 0.2 g (0.15 mol with respect to 100 mol of succinic acid) was added and reacted in a nitrogen atmosphere at 180 ° C. for 0.5 hour, then heated to 220 ° C. and reacted for 0.5 hour. It was. Subsequently, a polymerization reaction was performed for 2.5 hours under a reduced pressure of 0.07 × 10 ³ Pa. The obtained polyester was milky white, the number average molecular weight Mn was 75,300, and the melting point was 110 ° C. The introduction rate of lactic acid by ¹ H-NMR was 6.3 mol with respect to 100 mol of succinic acid.

  Moreover, the following were used as polylactic acid (B) and a pulp, and water was used as a cellulose amorphous area | region swelling agent (D).

[Polylactic acid (B)]
Product name “Lacty # 5400” manufactured by Shimadzu Corporation (number average molecular weight Mn: 88000, MFR: 4.5 g / 10 min., Melting point 173 ° C.)

[pulp]
Pretreated pulp (C): Kraft pulp refiner treated (water retention rate = 390
%, The fiber form photograph is as shown in FIG. 2 (a), the primary wall and
It can be seen that the outer layer of the secondary wall is damaged. )
Pulp without pretreatment: Kraft pulp without refiner treatment (water retention = 100%, fiber
The morphological photograph is as shown in FIG. 2 (b), and the surface is not damaged.
I understand that. )

Examples 1 and 2
Aliphatic polyester (A), polylactic acid (B), pulp, and water as a cellulose amorphous region swelling agent were kneaded by the twin-screw extruder with the formulation shown in Table 1. The specifications of the twin screw extruder used are as follows.

[Twin screw extruder]
Nippon Steel Works Co., Ltd. twin screw extruder “TEX30”
Screw diameter = 30mm
Screw length / screw diameter ratio = 42
Screw meshing = complete meshing type Screw rotation speed = 100 rpm
Processing capacity = 5 kg / hr as final composition amount

First, granules of aliphatic polyester (A) and polylactic acid (B) were blended and fed to a twin screw extruder with a gravimetric feeder. In the twin-screw extruder, three steps of a melting step, a melting / defining / dispersing step, and a water separation / extrusion step were set in the extrusion direction depending on the screw configuration. The set temperature of each process is as follows.
Melting process = 180 ° C
Melting / defibration / dispersion process = 150 ° C.
Water separation / extrusion process = 150 ° C

  Pulp is premixed with water as a cellulose amorphous region swelling agent at a predetermined ratio to make a mixed solution, and this mixed solution is a twin screw extruder at the boundary between the melting step and the melting / defibrating / dispersing step by a high-pressure pump. Injected into.

  The melt / defibration / dispersion step was performed at a pressure of 1.5 MPa by a screw configuration, and the pressure in the water separation / extrusion step was set at 53.2 kPa by a vacuum pump.

  The obtained composition was injection molded with an injection molding machine having the following specifications, and the obtained molded product was evaluated. The results are shown in Table 1.

  In addition, the form photograph of the fiber in the composition obtained in Example 2 is shown to Fig.3 (a).

[Injection molding machine]
"IT55T" injection molding machine manufactured by Toshiba Machine Co., Ltd.
Clamping pressure = 55t
Mold = ASTM
Mold temperature = 40 ℃
Barrel temperature setting = 170 ° C
Injection / holding time = 10 seconds

Examples 3 and 4
In Example 1, an aliphatic polyester composition was obtained in the same manner except that polylactic acid (B) was not used and the composition shown in Table 1 was used, and injection molding was performed in the same manner. It is shown in Table 1.

Comparative Example 1
In Example 1, an aliphatic polyester composition was obtained in the same manner except that pulp and water were not used, and injection molding was performed in the same manner, and the evaluation results of the injection molded product are shown in Table 1.

Comparative Example 2
In Example 2, an aliphatic polyester composition was obtained in the same manner except that untreated pulp was used in place of the pretreated pulp (C), and injection molding was performed in the same manner. It is shown in Table 1.

  A photograph of the morphology of the fibers in the composition obtained in Comparative Example 2 is shown in FIG.

Comparative Example 3
In Example 3, an aliphatic polyester composition was obtained in the same manner except that no water was used and water separation was not performed in a twin screw extruder, and injection molding was performed in the same manner. It is shown in Table 1.

Comparative Example 4
In Comparative Example 3, an aliphatic polyester composition was obtained in the same manner except that the pretreated pulp (C) was not used, and injection molding was performed in the same manner. The evaluation results of the injection molded product are shown in Table 1.

  2 (a), (b), FIGS. 3 (a), (b), and Table 1 reveal the following. That is, in the composition of Example 2 using the pulp in which the primary wall and the secondary wall outer layer were scratched by pretreatment, the pulp was uniformly finely dispersed in the form of microfibrils, whereas no pretreatment was performed. In the composition of Comparative Example 2 using pulp, the pulp is not defibrated and is scattered in a broken state. If the composition is a composition in which the pulp is uniformly finely dispersed in the form of microfibrils, a highly rigid and high strength fiber / biodegradable resin composite molded product can be obtained.

It is a typical perspective view which shows the laminated structure of a pulp and a cellulose fiber. FIG. 2A is an electron micrograph showing the form of the pretreated pulp used in the examples, and FIG. 2B is an electron micrograph showing the form of the untreated pulp used in the comparative example. 3 (a) is an electron micrograph showing the form of the fiber component in the composition obtained in Example 2, and FIG. 3 (b) is the form of the fiber component in the composition obtained in Comparative Example 2. It is an electron micrograph which shows.

Explanation of symbols

1 Primary wall 2 Secondary wall outer layer 3 Secondary wall middle layer 4 Secondary wall inner layer

Claims (10)

  Pulp made by damaging the outer wall of the primary wall and secondary wall.   Cellulosic fiber formed by damaging the outer wall of the primary wall and the secondary wall.   The fiber component is defibrated by kneading pulp and / or cellulosic fibers (C) that damage the outer wall of the primary wall and the secondary wall in the presence of the cellulose amorphous region swelling agent (D). A method for microfibrillation of pulp and / or cellulosic fibers. 1 to 99.9 parts by weight of a resin component comprising an aliphatic polyester (A) obtained by reacting (a) an aliphatic diol and (b) an aliphatic dicarboxylic acid and / or a derivative thereof;
Melting 99 to 0.1 parts by weight of a fiber component composed of pretreated pulp and / or cellulosic fibers (C) with damaged primary and secondary wall outer layers in the presence of a cellulose amorphous region swelling agent (D) A method for producing an aliphatic polyester composition, comprising kneading. From (a) aliphatic diol and (b) aliphatic polyester (A) obtained by reacting an aliphatic dicarboxylic acid and / or a derivative thereof, 1% by weight or more and polylactic acid (B) 99% by weight or less 1 to 99.9 parts by weight of the resin component
Melting 99 to 0.1 parts by weight of a fiber component composed of pretreated pulp and / or cellulosic fibers (C) with damaged primary and secondary wall outer layers in the presence of a cellulose amorphous region swelling agent (D) A method for producing an aliphatic polyester composition, comprising kneading.   The method for producing an aliphatic polyester composition according to claim 4 or 5, wherein the pretreated pulp and / or the cellulosic fiber (C) is further chemically modified.   The aliphatic polyester (A) according to any one of claims 4 to 6, wherein the aliphatic polyester (A) comprises (a) an aliphatic diol, (b) an aliphatic dicarboxylic acid and / or a derivative thereof, and (c) a bifunctional aliphatic. A method for producing an aliphatic polyester composition, which is obtained by reacting a hydroxycarboxylic acid and / or a derivative thereof.   8. The melt kneading treatment according to claim 4, wherein the melt-kneading process supplies the resin component, the fiber component, and the cellulose amorphous region swelling agent to a twin-screw extruder, and the cellulose A defibrating / dispersing step in which the fiber component is defibrated and dispersed in the resin component in the presence of a crystal region swelling agent, and then the resin component is melted and the fiber component is further defibrated and finely dispersed. A method for producing an aliphatic polyester composition, comprising: a dispersion step; and thereafter, a cellulose amorphous region swelling agent separation / extrusion step of separating the cellulose amorphous region swelling agent and extruding the kneaded product.   In any one of Claims 4 thru | or 8, the said melt-kneading process supplies the said resin component to a twin-screw extruder, the melting process which fuse | melts this resin component in this twin-screw extruder, and then said Melting / disaggregation in which a fiber component and a cellulose amorphous region swelling agent are injected under pressure into the twin-screw extruder, and the fiber component is defibrated and finely dispersed in the resin component in the presence of the cellulose amorphous region swelling agent. A method for producing an aliphatic polyester composition comprising: a fiber-dispersing step; and thereafter, a cellulose amorphous region swelling agent separating / extruding step of separating the cellulose amorphous region swelling agent and extruding the kneaded product.   The method for producing an aliphatic polyester composition according to any one of claims 4 to 9, wherein the water retention of the pretreated pulp and / or cellulosic fiber (C) is 150 to 600%.

Images