JP2008150492A - Resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition good in moldability and giving a molded product of high heat distortion temperature. <P>SOLUTION: The resin composition compises (a) 100 pts.mass of polylactic acid, (b) 0.01-160 pts.mass of a cellulose fiber and (c) 0.01-20 pts.mass of a crystal nucleating agent. In this resin composition, it is preferable that the component (b) be such that a cellulose fiber assembly has been disassembled by a rotating blade-bearing mixer, and the component (c) consist of a phenylphosphonic acid salt. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resin composition having good moldability and improving the heat distortion temperature of a molded product.

  It is known that polylactic acid, when left in a wet state such as soil or seawater, significantly decreases in strength within a few weeks and disappears without retaining its original shape in about one to several years. . Furthermore, the degradation product of polylactic acid is characterized by lactic acid, carbon dioxide and water that are harmless to the human body.

  For this reason, resin compositions based on polylactic acid and their molded products have been developed, but polylactic acid has a significantly slower crystallization rate than existing thermoplastic resins, and the existing molding method uses a molding cycle. Becomes very long and cannot be commercialized in practice. Even if the molding is performed over a very long time, there is room for improvement because the use is limited in that the heat resistance (thermal deformation temperature) of the molded product is low.

In order to solve the above problems, the invention of the lactic acid-based polymer composition of Patent Document 1 attempts to solve the problem by adding an organic silicon compound and a crystal nucleating agent to the lactic acid-based polymer (polylactic acid). The talc disclosed as is not sufficient as a crystal nucleating agent by itself and is still unsuitable for practical use. Patent Document 2 describes that waste paper powder as an organic filler, crystallization accelerator (crystal nucleating agent) and talc as an inorganic filler can be added to polylactic acid resin, but plasticity is used as a crystallization accelerator. Since the agent is added, the rigidity decreases. In Patent Document 3, a plasticizer and a crystal nucleating agent are also added to improve the crystallization speed. However, since the rigidity is lowered, it is not suitable for practical use as an injection molded body other than a sheet.
JP 2004-352908 A Japanese Patent Laid-Open No. 2005-2174 Japanese Patent No. 3410075

  The present invention provides a resin composition and a molded product thereof that can be applied to new applications because the molding cycle during injection molding is short and the strength and heat distortion temperature when molded are improved. It is an issue to provide.

  As a result of intensive studies, the present inventors have found that the above problem can be solved by the synergistic action of the cellulose fiber and the crystal nucleating agent by including in the polylactic acid a combination of the cellulose fiber and the crystal nucleating agent. It was.

  As a means for solving the problems, the present invention comprises (b) 0.01 to 160 parts by mass of cellulose fiber and (c) 0.01 to 20 parts by mass of a crystal nucleating agent with respect to 100 parts by mass of polylactic acid. A resin composition and a molded product thereof are provided.

  In the resin composition of the present invention, the molding cycle is shortened, the resulting molded product has good rigidity, and the heat distortion temperature is high.

<(A) Polylactic acid>
The component (a) polylactic acid is a polymer mainly composed of L-lactic acid and / or D-lactic acid, and is a copolymer with other monomer copolymerizable with the lactic acid (preferably a copolymer). Other monomer units in it may be 30 mol% or less). Known polylactic acid can be used as the component (a), and for example, those described in Patent Documents 1, 2, and 3 can be used.

<(B) Cellulose fiber>
Examples of the cellulose fiber (b) include hemp fiber, bamboo fiber, cotton fiber, wood fiber, kenaf fiber, hemp fiber, jute fiber, banana fiber, coconut fiber, and the like. The cellulose fiber preferably has a high α-cellulose content from the viewpoint of high thermal stability, more preferably 80% by mass or more, still more preferably 85% by mass or more, and particularly preferably 90% by mass or more.

  The average fiber diameter of the cellulose fibers is preferably 0.1 to 1000 μm, more preferably 1 to 500 μm, still more preferably 5 to 200 μm, and particularly preferably 10 to 50 μm.

  The average fiber length of the cellulose fibers is preferably 0.01 to 100 mm, more preferably 0.01 to 50 mm, still more preferably 0.1 to 10 mm, and particularly preferably 0.1 to 5 mm.

  The aspect ratio (length / diameter) of the cellulose fiber is preferably 2 to 1000, more preferably 3 to 500, still more preferably 5 to 200, and particularly preferably 5 to 100.

The cellulose fiber may be surface-treated with a coupling agent (a silane coupling agent having a functional group such as an amino group, a substituted amino group, an epoxy group, or a glycidyl group). The cellulose fiber as the component (b) is a cellulose fiber. The aggregate is preferably defibrated with a mixer having rotating blades.

  The content of the cellulose fiber as the component (b) in the composition is 0.01 to 160 parts by mass, preferably 0.1 to 150 parts by mass with respect to 100 parts by mass of the polylactic acid as the component (a). More preferably, it is 1-140 mass parts.

<(C) Crystal nucleating agent>
As the crystal nucleating agent of the component (c), known organic crystal nucleating agents and inorganic crystal nucleating agents can be used.

  Inorganic crystal nucleating agents include talc, kaolin, montmorillonite, synthetic mica, clay, zeolite, silica, graphite, carbon black, zinc oxide, magnesium oxide, titanium oxide, calcium sulfide, boron nitride, calcium carbonate, barium sulfate, oxidation Examples thereof include aluminum, neodymium oxide, dibasic aluminum phosphate, tricalcium phosphate, and metal salts of phenylphosphonate. These inorganic crystal nucleating agents may be modified with an organic substance in order to enhance the dispersibility in the composition.

  Organic crystal nucleating agents include phenylphosphonic acid (salts) or derivatives thereof such as zinc phenylphosphonate, phenylphosphonic dichloride, dimethyl phenylphosphonate, melamine phosphate, bis (p-methylpentylidene) sorbitol, bis (p-Toluylidene) sorbitol and the like are preferable.

Other organic crystal nucleating agents include sodium benzoate, potassium benzoate, lithium benzoate, calcium benzoate, magnesium benzoate, barium benzoate, lithium terephthalate, sodium terephthalate, potassium terephthalate, calcium oxalate, Sodium laurate, potassium laurate, sodium myristate, potassium myristate, calcium myristate, sodium octacosanoate, calcium octacosanoate, sodium stearate, potassium stearate, lithium stearate, calcium stearate, magnesium stearate, barium stearate , Sodium montanate, calcium montanate, sodium toluate, sodium salicylate, potassium salicylate, zinc salicylate, Mini um dibenzoate, potassium dibenzoate, lithium dibenzoate, sodium β- naphthalate, organic carboxylic acid metal salts such as sodium cyclohexanecarboxylate,
organic sulfonates such as sodium p-toluenesulfonate and sodium sulfoisophthalate,
Carboxylic acid amides such as stearic acid amide, ethylenebislauric acid amide, palmitic acid amide, hydroxystearic acid amide, erucic acid amide, trimesic acid tris (t-butylamide),
Polymers such as low density polyethylene, high density polyethylene, polypropylene, polyisopropylene, polybutene, poly-4-methylpentene, poly-3-methylbutene-1, polyvinylcycloalkane, polyvinyltrialkylsilane, high melting point polylactic acid,
Sodium salt or potassium salt of a polymer having a carboxyl group such as sodium salt of ethylene-acrylic acid or methacrylic acid copolymer, sodium salt of styrene-maleic anhydride copolymer (so-called ionomer), benzylidene sorbitol and its derivatives,
Phosphorus compound metal salts such as sodium-2,2′-methylenebis (4,6-di-t-butylphenyl) phosphate and 2,2-methylbis (4,6-di-t-butylphenyl) sodium Can be mentioned.

  The content of the crystal nucleating agent as the component (c) in the composition is 0.01 to 20 parts by mass, preferably 0.05 to 10 parts by mass with respect to 100 parts by mass of the polylactic acid as the component (a). Yes, more preferably 0.1 to 5 parts by mass.

  The composition of the present invention includes carbon black, inorganic pigment, organic pigment, dye, auxiliary colorant, dispersant, stabilizer, plasticizer, modifier, ultraviolet absorber or light stabilizer, oxidation, if necessary. An inhibitor, an antistatic agent, a lubricant, a mold release agent, a crystal accelerator, an elastomer for improving impact resistance, and the like can be blended.

  The composition of the present invention is not limited in its production method as long as the contained cellulose has a fibrous shape. For example, for the polylactic acid (a), the cellulose fiber (b) And a crystal nucleating agent of the component (c) can be blended and manufactured by applying a known method such as melt kneading by an extruder. (B) The cellulose fiber of a component can use what was obtained by applying the 1st process of the manufacturing method shown below other than the well-known thing including a commercial item, for example.

  The composition of the present invention can also be obtained by applying a production method having the following first to third steps.

[First step]
In the first step, the cellulose fiber aggregate is put into a mixer having rotating blades as stirring means, and the cellulose fiber aggregate is defibrated by stirring at high speed.

  The mixer only needs to have rotating blades as stirring means, and preferably has heating means. For example, a Henschel mixer manufactured by Mitsui Mining Co., Ltd., FM20C / I (capacity 20 L), ( Kawata Supermixer SMV-20 (capacity 20 L) can be used.

  The rotating blades are usually composed of two upper blades and lower blades, or three upper blades, intermediate blades, and lower blades, but the number is not limited. Although there are no restrictions on the shape of the blade, for example, the kneading type is used for the upper blade, the high circulation / high load is used for the lower blade, and the melt is used when the intermediate blade is used.

  In the first step, it is preferable to stir in the range of the average peripheral speed of the rotating blades during stirring in the range of 10 to 100 m / second, more preferably the average peripheral speed is 10 to 90 m / second, and still more preferably the average peripheral speed is 10 Stir at ~ 80 m / sec.

  The treatment in the first step is not limited as long as the cellulose fiber aggregate can be sufficiently defibrated. For example, the point in time when the cellulose fiber aggregate has been visually confirmed to be cottony can be confirmed. The end of Since the average peripheral speed and stirring time of the rotating blades change depending on the type, shape, size, input amount, and the like of the cellulose fiber aggregate, the time point when it changes to cotton as described above may be used as a reference. Is preferred.

  Cellulose fiber aggregates are a combination of many cellulose fibers, which may be natural or industrial products, hemp fiber, bamboo fiber, cotton fiber, wood fiber, kenaf fiber, hemp fiber, jute fiber, banana Aggregates such as fibers and coconut fibers can be used.

  The cellulose fiber preferably has a high α-cellulose content from the viewpoint of high thermal stability, more preferably 80% by mass or more, still more preferably 85% by mass or more, and particularly preferably 90% by mass or more.

  As the cellulose fiber aggregate, a pulp sheet or a cut product thereof is preferable. The thickness, shape, and size of the pulp sheet or the cut product thereof are not particularly limited, and can be selected within a range in which the operation of adding to the mixer and the stirring operation can be performed smoothly.

  When the cellulose fiber aggregate is a sheet, for example, a sheet having a thickness of 0.1 to 5 mm, preferably 1 to 3 mm, a width of 1 to 50 cm, and a length of about 3 to 100 cm can be used.

  When the cellulose fiber aggregate is a cut product of a sheet, for example, a strip having a thickness of 0.1 to 5 mm, preferably 1 to 3 mm, a width of 2 mm to 1 cm, and a length of about 3 mm to 3 cm, or A rectangular shape having a side of about 2 mm to 1 cm is preferable.

  The moisture content of the cellulose fiber aggregate is preferably 20% by mass or less, more preferably 17% by mass or less, and still more preferably 15% by mass or less. A water content of 20% by mass or less is preferable because the temperature rise due to generation of frictional heat is facilitated in the next step, and the cellulose fiber aggregate is easily defibrated and no aggregate remains. The moisture content is determined by moisture measurement using the Karl Fuscher method.

  If necessary, organic fibers other than cellulose fibers can be used. In the total amount of cellulose fibers and organic fibers, the ratio of cellulose fibers is preferably 50% by mass or more, more preferably. It is 55 mass% or more. Examples of organic fibers other than cellulose fibers include nylon fibers, polyester fibers, and acrylic fibers.

[Second step]
In the second step, the polylactic acid (a) is added to the mixer in the mixer and stirred to melt the polylactic acid by the generated frictional heat so that the polylactic acid adheres to the fibrillated cellulose fibers. Get. The 1st process and the 2nd process can be made into one continuous process, without stopping stirring of a mixer.

  In the first step, since the cellulose fiber aggregate is defibrated in the mixer, a required amount of polylactic acid is added thereto and stirred at a high speed. This high-speed stirring generates frictional heat and raises the temperature in the mixer, so that the polylactic acid melts and adheres to the fibrillated cellulose fibers, thereby obtaining a mixture of cellulose fibers and polylactic acid.

  In the second step, it is preferable to stir in the range of the average peripheral speed of the rotating blades during stirring in the range of 10 to 100 m / second, more preferably the average peripheral speed is 10 to 90 m / second, and still more preferably the average peripheral speed is 10 Stir at ~ 80 m / sec. If stirring is continued, the temperature in the mixer will continue to rise, and the power of the motor will increase. It is preferable to reduce the rotational speed by gradually or decelerating the stirring speed in accordance with the increase in power and the temperature in the mixer so that the average peripheral speed falls within the above range.

  When stirring is continued in this state, the power increases again, so the mixture is discharged to the cooling mixer used in the next third step to be connected. At this time, in this mixture, the fibrillated cellulose fibers are almost uniformly attached to the polylactic acid.

  In the second step, the mixer can be heated by a heating means in order to assist the temperature increase in the mixer and facilitate the production of a mixture of cellulose fibers and polylactic acid. The temperature at this time is preferably about 120 to 140 ° C.

[Third step]
In the third step, the mixture obtained in the second step is stirred at a low speed while being cooled. By the treatment in this step, the mixture is solidified (granulated by solidification). In the third step, in order to increase the cooling efficiency of the mixer, it is preferable to use a mixer (preferably having a cooling means) different from the mixer used in the first step and the second step.

  In the third step, it is preferable to stir in the range of 1 to 30 m / sec of the average peripheral speed of the rotating blades during stirring, more preferably 2 to 25 m / sec, more preferably 3 to 3. Stir at ~ 25 m / sec. The stirring speed in the third step is smaller than the stirring speed in the first step and the second step.

  In the treatment in the third step, the treatment in the third step can be completed when the mixture of polylactic acid and cellulose fiber is solidified to such an extent that it can be handled as a molding material. In addition, since the polylactic acid once solidified will re-melt if the temperature in the mixer rises too much due to generation of frictional heat, it is preferable to manage the temperature in the mixer also in the third step.

[Fourth step]
By such treatment, a solidified product (granulated product) containing polylactic acid and cellulose fiber is obtained. The composition of the present invention can be obtained by blending the granulated product with the crystal nucleating agent of component (c) and optional components as required.

  The composition of the present invention can be molded into a desired shape by applying a known molding method such as an injection molding method. The molded product of the present invention may be an injection molded product, an extrusion molded product, a blow molded product, or the like as a molded product made of the resin composition of the present invention, and may also be used as a sheet, film, fiber, or the like. Can do. In addition, these molded products can be used for various applications such as electric / electronic parts (various housings, gears, gears, etc.), building members, civil engineering members, agricultural materials, automobile parts (interior / exterior parts, etc.) and daily necessities. it can.

Examples and Comparative Examples [First Step]
Heat the heater mixer (upper blade: kneading type, lower blade: high circulation / high load, with heater and thermometer, capacity 20L, Henschel mixer FM20C / I, manufactured by Mitsui Mining Co., Ltd.) to 140 ° C. Various cellulose fiber products shown in Table 1 were charged and stirred at an average peripheral speed of 50 m / sec. After about 2 minutes, the cellulose fiber product changed to cotton.

[Second step]
Subsequently, after the polylactic acid was charged into the heater mixer, stirring was continued at an average peripheral speed of 50 m / sec. The power of the motor at this time was 2.5 kW. When the mixer temperature reached 120 ° C., MPP was added and stirring was continued.

  At about 10 minutes, power started to increase. One minute later, the power increased to 4 kW, so the peripheral speed was reduced to a low speed of 25 m / sec. Furthermore, the power started to increase again due to the continued low speed stirring. After 1 minute and 30 lines from the start of low speed rotation, the current value reached 5 kW, so the outlet of the mixer was opened and discharged to the connected cooling mixer.

[Third step]
Cooling mixer [Rotating blade: Standard blade for cooling, with water cooling means (20 ° C) and thermometer, capacity 45L, product name cooler mixer FD20C / K, manufactured by Mitsui Mining Co., Ltd.) Start stirring at an average peripheral speed of 10m / sec. The stirring was terminated when the temperature in the mixer reached 80 ° C. By the treatment in the third step, the mixture of cellulose fibers and polylactic acid was solidified, and a granulated product having a diameter of about several mm to 2 cm was obtained.

[Fourth step]
A crystal nucleating agent (zinc phenyl sulfonate) in an amount shown in Table 1 was added to the obtained granulated product to obtain a composition shown in Table 1. The following tests were conducted using the obtained composition. The results are shown in Table 1.

[Use ingredients]
The detail of the component used by the Example and comparative example which are shown in Table 1 is as follows.

(A) Component Polylactic acid: LACEEA H440 Made by Mitsui Chemicals (b) Component Cellulose fiber (aggregate): LDPR Made by Nippon Paper Industries Co., Ltd. (c) Component Phenylsulfonic acid zinc salt: PPA-Zn, Nissan Chemical Co. melamine phosphate : Melapur200 / 70
Tricalcium phosphate (hydroxyapatite)
Bis (p-methylpentylidene) sorbitol, Bis (p-toluylidene) sorbitol: Gelol MD-LM30, manufactured by Shin Nippon Rika (Other components)
Antioxidant 1: Irganox 1010, manufactured by Ciba Special Co., Ltd. Antioxidant 2: IRGAFOS 168, manufactured by Ciba Special Co., Ltd.

〔Test method〕
(1) Flexural modulus: measured according to ISO178.

(2) Charpy impact strength
Measured according to ISO179. As the sample, both an injection molded specimen left in a room at 23 ° C. for one day after molding and an annealed specimen were used. For annealing, the test piece was placed in a 100 ° C. atmosphere for 3 hours with a hot air circulation dryer, and then conditioned in a 23 ° C. room for 24 hours and then tested.

(3) Deflection temperature under load (HDT)
Measured according to ISO75. As the sample, both an injection molded specimen left in a room at 23 ° C. for one day after molding and an annealed specimen were used. For annealing, the test piece was placed in a 100 ° C. atmosphere for 3 hours with a hot air circulation dryer, and then conditioned in a 23 ° C. room for 24 hours and then tested.

(4) Molding cycle (seconds)
The molding time was 200 ° C., the mold temperature was 40 ° C., the injection process was 20 seconds, and the mold was molded with a mold having the following shape with a 100-ton molding machine, and the minimum time (seconds) that could be released from the mold was measured. Molding was performed 10 times, and the average value was displayed.

  Mold shape: Use ISO standard mold. Length 17cm x parallel part width 1cm x thickness 4mm. Filled from the side gate.

Claims (4)

  (A) A resin composition containing 0.01 to 160 parts by mass of cellulose fiber and (c) 0.01 to 20 parts by mass of a crystal nucleating agent with respect to 100 parts by mass of polylactic acid.   The resin composition according to claim 1, wherein the cellulose fiber as the component (b) is a cellulose fiber aggregate that has been defibrated with a mixer having rotating blades.   The resin composition according to claim 1 or 2, wherein the crystal nucleating agent of component (c) comprises phenylphosphonic acid (salt) or a derivative thereof. The molded article obtained from the resin composition in any one of Claims 1-3.