JP5592696B2 - Aliphatic polyester resin composition - Google Patents

Description

  The present invention relates to an aliphatic polyester resin composition comprising a blend containing an aliphatic polyester resin and cellulose fibers, and relates to a resin composition applied in various fields such as the automobile field.

Resin composition products (for example, automobile cable casings) applied in various fields as well as in the automotive field are generally those using fossil-derived materials. When it became a target for disposal due to its life, etc., it was simply disposed of by landfilling. However, final disposal sites related to landfilling tend to decrease year by year, and countermeasures are desired. As a countermeasure, a method of using the product as an incineration process or thermal energy has been studied. However, since this method requires a combustion process, there is a possibility that various harmful substances or CO ₂ may be discharged. is there.

  Thus, in recent years, attempts have been made to apply resin compositions using non-fossil-derived materials. For example, since a resin composition using an aliphatic polyester resin such as polylactic acid known as a plant-derived material has biodegradability, for example, even when disposed by landfill treatment or the like as described above It is attracting attention as a relatively small environmental load and can contribute to environmental conservation.

  Aliphatic polyester-based resins such as polylactic acid are crystalline polymer components, but the crystallization speed is slower than that of fossil-derived materials, and the resin obtained by simply molding the aliphatic polyester-based resin The crystallinity of the composition will be low. In general, resin compositions with low crystallinity are considered to have poor properties such as productivity (moldability), heat resistance, impact resistance, and hydrolysis resistance. It is considered important.

  Therefore, a technique has been adopted to increase the crystallization speed by blending an aliphatic filler such as glass fiber or talc as a crystal nucleating agent with an aliphatic polyester-based resin. Attempts have been made to apply and further contribute to environmental conservation. For example, an aliphatic polyester resin composition containing cellulose fibers as a crystal nucleating agent is known (for example, Patent Document 1).

JP 2007-21111 (paragraphs [0004], [0014], etc.).

  As described above, the cellulose fiber is used as a crystallization agent to contribute to environmental conservation, and the average particle size (or length) of the cellulose fiber is adjusted to increase the crystallization speed. In order to make the characteristics of the aliphatic polyester resin composition having a relatively low crystallization rate more satisfactory, it is required to further improve the crystallization rate.

  The present invention is a technical idea created to solve the above-described problems. Specifically, one aspect of the aliphatic polyester resin composition according to the present invention is at least an aliphatic polyester resin, a flat cellulose. It is characterized by crystallizing a compound containing a system fiber.

  Polylactic acid can be used as the aliphatic polyester resin. Further, as the cellulosic fiber, a fiber having a fiber length of several hundreds μm can be used, and a fiber having a fiber width of several tens of μm and a fiber thickness of several μm can be used.

  In general, in the field of resin compositions, in order to adjust the shape of the fiber as a crystallization agent, a technique of reducing fiber hardness through a process such as acid hydrolysis treatment in advance has been adopted. A simple cellulosic fiber (for example, a fiber having a substantially circular cross section; hereinafter referred to as a linear fiber) that has been cut into a predetermined size through a flat fiber cell is applied. In the examples, there was no idea of applying flat fibers), that is, fibers having an unshaped shape, and it was not even studied.

  On the other hand, when flat cellulosic fibers are applied, the surface area is large compared to conventional linear fibers, so when blended with aliphatic polyester resins, the aliphatic polyester resins and The area of the interface with the cellulosic fiber also increases.

  As described above, according to the present invention, it is possible to contribute to environmental conservation, and it is possible to ensure a sufficient crystallization rate (for example, sufficient as compared with linear cellulosic fibers), and an aliphatic polyester resin composition. It can also contribute to the improvement of various properties.

Fiber length distribution (S1, H1) of cellulosic fibers used in this example. The chemical structure figure in a cellulosic fiber. The wide spectrum figure (S1, H1) in the cellulosic fiber used in the present Example. The wide spectrum figure (S2, H2) in the cellulosic fiber used in the present Example. The narrow spectrum figure (S1, H1) in the cellulosic fiber used in the present Example. The narrow spectrum figure (S2, H2) in the cellulosic fiber used in the present Example. The specific surface area result figure (S1-H2) in the cellulosic fiber used in the present Example. The SEM photograph figure (S1, H1) in the cellulosic fiber used in the present Example. The SEM photograph figure (S2, H2) in the cellulosic fiber used in the present Example. The isothermal crystallization rate result figure (S1-H2) by the cellulose fiber used in the present Example.

  The aliphatic polyester resin composition of the present embodiment is obtained by blending at least a flat cellulosic fiber as a crystal nucleating agent with an aliphatic polyester resin, and crystallizing the blend. Depending on the product to be applied (for example, the case of a cable for an automobile cable, etc.), various additives may be used as appropriate in addition to the aliphatic polyester resin and cellulose fiber as shown below. Well-known manufacturing methods in the field can be applied as appropriate.

[Aliphatic polyester resin]
Examples of the aliphatic polyester resin include a polymer mainly composed of an aliphatic hydroxycarboxylic acid, or a polymer mainly composed of an aliphatic polycarboxylic acid and an aliphatic polyhydric alcohol. For example, polymers having aliphatic hydroxycarboxylic acid as a main constituent include polylactic acid resins, polyglycolic acid, poly-3-hydroxybutyric acid, poly-4-hydroxybutyric acid, poly-4-hydroxyvaleric acid, poly-3-hydroxy. Examples include hexanoic acid and polycaprolactone. Examples of the polymer mainly composed of an aliphatic polycarboxylic acid and an aliphatic polyhydric alcohol include polyethylene adipate, polyethylene succinate, polybutylene adipate, and polybutylene succinate.

[Cellulose fiber]
Cellulosic fibers include artificially extracted and synthesized cellulose, lignocellulose, and fibers obtained from cellulosic biomass containing at least one of these celluloses and lignocelluloses. The flat thing cut | judged to the predetermined length according to a resin composition is applied.

  Cellulose biomass containing cellulose includes pulverized wood pulp, cotton linter (for example, obtained from cottonseed), cotton flock, human silk flock (for example, human silk cut). Cellulosic biomass containing lignocellulose includes lignocellulosic fibers and lignocellulose. Specific examples include wood pulp, refiner grand pulp (RGP), paper pulp, waste paper, crushed wood pieces, wood flour, saw dust, canna waste, bamboo flour, bagasse, fruit shell flour, and the like.

  Such a cellulosic fiber not only acts as a reinforcing filler for the aliphatic polyester resin by being blended in the aliphatic polyester resin composition, but also when the aliphatic polyester resin solidifies from a molten state. It also acts as a crystal nucleating agent that promotes crystallization.

  As a method for obtaining a flat cellulosic fiber as in the present embodiment, for example, a method of simply cutting the cellulosic fiber without performing the acid hydrolysis treatment as described above may be mentioned. In the case of this method, the cellulosic fiber is cut while applying a shearing force (pressing force) in the cross-sectional direction, so that the intended flat fiber can be easily obtained. Conventionally, when cellulosic fibers are used as a crystal nucleating agent for an aliphatic polyester resin composition, it is considered necessary to apply a linear fiber having a relatively uniform shape. Although the technique of reducing the hardness of the system fiber and facilitating cutting into a linear shape has been adopted, in the case of this embodiment, the acid hydrolysis treatment is not required.

  The size of the flat fibers can be appropriately set according to the target resin composition, but is cut to a fiber length of, for example, several hundreds of μm (in the examples, about 140 μm to 200 μm). A fiber having a fiber width of several tens of μm (in the embodiment, about 20 μm level) and a fiber thickness of several μm (in the embodiment, about 1.5 μm to 2.5 μm level). And those having a larger dimension in the fiber thickness direction than in the width direction).

  The blending amount can be appropriately set according to the target resin composition. For example, about 10 to 900 parts by weight is blended with 100 parts by weight of the aliphatic polyester resin. If the blending amount of the cellulosic fibers is too small, it becomes difficult to obtain a desired crystallization rate. If the blending amount is excessive, uniform dispersibility when the aliphatic polyester resin and the cellulosic fibers are kneaded. May decrease.

[Other ingredients]
In addition to the above aliphatic polyester resins and cellulose fibers, polybasic acid anhydrides, organic peroxides, modified aliphatic polyester resins, inorganic crystal nucleating agents, etc., depending on the intended resin composition May be blended as appropriate.

<Polybasic acid anhydride, organic peroxide>
The polybasic acid anhydride is added to the aliphatic polyester resin composition mainly composed of aliphatic polyester resin and cellulose fiber as necessary. These polybasic acid anhydrides include maleic anhydride, succinic anhydride, phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, dichloromaleic anhydride, itaconic anhydride, tetrabromophthalic anhydride, het anhydride , Trimetic anhydride, pyromellitic anhydride, and the like. As a compounding quantity of these polybasic acid anhydrides, compounding in 0.1-20 weight part with respect to 100 weight part aliphatic polyester-type resin is mentioned.

  An organic peroxide polymerizes the blended polybasic acid anhydride to an aliphatic polyester resin. Examples of the organic peroxide include benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (peroxybenzoate) hexyne-3,1,3- Bis (t-butylperoxyisopropyl) benzene, lauroyl peroxide, t-butylperoxyphenyl acetate and the like can be mentioned. Such an organic peroxide can also be used individually by 1 type, and can also use 2 or more types together. As a compounding quantity of these organic peroxides, it is mentioned to mix | blend in the range of 0.001-2 weight part with respect to 100 weight part aliphatic polyester-type resin.

  As described above, the polybasic acid anhydride and the organic peroxide are blended and chemically reacted with the aliphatic polyester resin, whereby a polar group having affinity with the cellulosic fiber is provided in the aliphatic polyester resin. It will be. As a result, the compatibility between the aliphatic polyester resin and the cellulosic material is improved, and the cellulosic material is easily dispersed finely and uniformly in the matrix of the aliphatic polyester resin. As described above, since the finely and uniformly dispersed cellulose fiber acts as a crystal nucleating agent, the aliphatic polyester resin tends to have a high crystallization rate when cooled and solidified after being heated and melted. .

<Modified aliphatic polyester resin>
The modified aliphatic polyester resin is added to the aliphatic polyester resin composition as necessary. This modified aliphatic polyester resin can be used together with the polybasic acid anhydride and organic peroxide, or in place of the polybasic acid anhydride and organic peroxide. This modified aliphatic polyester resin is obtained by modifying an aliphatic polyester resin with a modifier (compound) having at least one polar group selected from a carboxyl group and an acid anhydride group.

  The modified aliphatic polyester resin is not limited to one obtained by modifying the same compound as the aliphatic polyester resin that is the main component of the aliphatic polyester resin composition, but other different aliphatic polyesters. What modified | denatured the system resin compound may be used. Specific examples of the modifying agent having a carboxyl group include aliphatic carboxylic acids such as maleic acid, oxalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, carbaryl acid, cyclohexanedicarboxylic acid, and cyclopentanedicarboxylic acid. And aromatic carboxylic acids such as acid, terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, trimesic acid, trimellitic acid, and pyromellitic acid. Specific examples of the modifier having an acid anhydride group include maleic anhydride, itaconic anhydride, pyromellitic anhydride, cis-4-cyclohexane-1,2-dicarboxylic anhydride, 1,2,4, Examples include 5-benzenetetracarboxylic dianhydride and 5- (2,5-dioxytetrahydroxyfuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic-dicarboxylic anhydride.

  When the modified aliphatic polyester resin as described above is blended, the compatibility between the aliphatic polyester resin and the cellulosic fiber is improved, and the cellulosic material is made fine and uniform in the matrix of the aliphatic polyester resin. Can be dispersed. Cellulose fibers finely and uniformly dispersed in this way act as a crystal nucleating agent, and therefore aliphatic polyester resins tend to increase in crystallization speed when cooled and solidified after heating and melting. .

<Inorganic crystal nucleating agent>
The inorganic crystal nucleating agent is blended in combination with the polybasic acid anhydride and the organic peroxide added to the aliphatic polyester resin composition. Alternatively, the inorganic crystal nucleating agent is blended in combination with the modified aliphatic polyester resin added to the aliphatic polyester resin composition.

  Specific examples of such an inorganic crystal nucleating agent include talc, silica, montmorillonite, kaolinite, clay, mica, titanium oxide, magnesium oxide, calcium carbonate and the like, and talc is particularly preferable. In addition, it is not particularly limited as long as it is generally used as a polymer crystal nucleating agent, and these crystal nucleating agents include various types in order to improve affinity and dispersibility with a resin. A titanate coupling agent, a silane coupling agent, an unsaturated carboxylic acid, a fatty acid, or a surface treated with a derivative thereof may be used.

The size of the inorganic crystal nucleating agent is, for example, an average particle size (average particle size obtained from a particle size value of a cumulative amount of 50% by weight read from a particle size cumulative distribution curve measured by a laser diffraction scattering method) 0.001 μm in the range of ～3.0Myuemu, and a specific surface area include those in the range of 15m ² / g~1000m ² / g. Moreover, as a compounding quantity, it is mentioned as the range of 0.01-50 weight part with respect to 100 weight part of aliphatic polyester-type resin.

  By blending the inorganic crystal nucleating agent in this way, crystallization of the aliphatic polyester resin composition tends to be promoted.

<Others>
If necessary, various materials well known in the field of aliphatic polyester resin compositions, such as plasticizers, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, hydrolysis inhibitors, antistatic agents, Release agents, fragrances, lubricants, flame retardants, foaming agents, pigments, colorants, various fillers, fillers, reinforcing materials, antibacterial and antifungal agents, and various additives for starch substances such as rice In this case, it may be blended appropriately.

[Production method]
The aliphatic polyester resin composition of the present embodiment can be produced by various methods well known in the field of the aliphatic polyester resin composition. For example, the aliphatic polyester resin, cellulose fiber and the like are predetermined. It can be carried out by mixing at a ratio, putting it in a hopper of a molding machine, and melting it. The molten polyester resin composition thus melted may be immediately molded to form a molded body.

  Moreover, the arbitrary combination of each said component which comprises an aliphatic polyester resin composition may be melt-mixed, once pelletized, and then it may be remelted and shape | molded as needed. In order to mix uniformly, the method of once pelletizing is mentioned.

  The melt extrusion temperature and reaction melting time of the aliphatic polyester resin composition at the time of molding the molded product can be appropriately selected in consideration of the melting point of the aliphatic polyester resin used and the mixing ratio of other components, for example, For example, the melt extrusion temperature is set to about 100 to 250 ° C., and the reaction melting time is set to about several tens of minutes. The method for adding the inorganic crystal nucleating agent is not particularly limited, but may be premixed in the pellet, or may be added and mixed when the pellet is remelted.

  As a molding method of the molded article of the aliphatic polyester resin composition according to the present embodiment, a molding method known in the field of general aliphatic polyester resin compositions can be applied, and specific examples include injection molding, Gas injection molding, extrusion molding, blow molding, inflation molding, saddle extrusion molding, injection blow molding, vacuum pressure molding, compression molding and the like can be mentioned. As a method for obtaining a molded article having good moldability and appearance, a method of filling a molten product of an aliphatic polyester resin composition into a mold and crystallizing it as it is in the mold, or cooling to form a molded article. After taking out, it can be considered to crystallize the molded article by, for example, a method of holding and crystallizing at a crystallization temperature for a certain time.

  The temperature for crystallization is a temperature not lower than the glass transition point and not higher than the melting point, and specifically includes a range of about 60 ° C. to 160 ° C. The crystallized molded body can be molded into various shapes by various methods, and is a film, a sheet, an injection molded body, a blow molded body, an extruded molded body, a vacuum / pressure molded body, and a laminated structure. It can be used as containers, foams, fibers, woven fabrics, non-woven fabrics, etc. in various fields such as the automobile field, electrical / electronic field, packaging field, agricultural field, fishery field, medical field, and other general goods.

  Examples of applications of the molded body according to the present embodiment include, in the automobile field, cables (housing, etc.), bumpers, radiator grills, side moldings, garnishes, wheel covers, aero parts, instrument panels, door trims, seat fabrics, doors. It can be used for interior and exterior parts such as handles and floor mats.

  In home appliances and electronic applications, personal computer housings and internal parts, CRT display and LCD housings and internal parts, printer housings and internal parts, mobile phone housings and internal parts such as mobile phones, mobile personal computers, handheld types, recording media ( CD, DVD, MD, FD, etc.) Useful for housings and internal parts of drives, housings and internal parts of copiers, facsimiles, etc., as well as housings and internal parts of electronic and home appliances such as VTRs, digital cameras, TVs, refrigerators, and air conditioners Can be used.

  In the packaging field, various packaging is possible as a foaming buffer, a packaging film, and a sheet. In the medical field, it can be used as sanitary materials such as medical materials and sanitary products. In addition, it is also useful for leisure goods, cards such as IC cards, trays, plastic cans, containers, containers such as containers, tanks, baskets, baskets, chairs, tables, etc.

  Next, based on the aliphatic polyester resin composition of the present embodiment, the crystallization rate was verified using an aliphatic polyester resin and cellulose fiber as shown below.

  As the aliphatic polyester resin, polylactic acid PLA (hereinafter referred to as resin PLA) manufactured by Nature Works was used. The cellulosic fibers are KC flocs manufactured by Nippon Paper Industries Co., Ltd., and flat fibers (hereinafter referred to as flat fibers H1, H2) cut without being subjected to acid hydrolysis treatment as shown in Table 1 below. ) And two types of linear fibers cut by acid hydrolysis (hereinafter, linear fibers S1, S2) were used.

  In addition, when the fiber length, fiber width, and fiber thickness of each fiber were examined based on ISO / FDIS16065-2, as shown in Table 2 below, the flat fiber H1, the linear fiber S1, and the flat shape It can be seen that the fiber H2 and the linear fiber S2 have substantially the same fiber length, but have a difference in fiber width and fiber thickness.

  Further, when the fiber length distribution in the flat fibers H1 and the linear fibers S1 was examined by a fiber length / shape measuring machine (manufactured by L & W Fiber Tester Lorentzen and Wettre), they were substantially the same as shown in FIG. Can be read. It was confirmed that the fiber length distributions of the flat fibers H2 and the linear fibers S2 were substantially the same as each other, like the flat fibers H1 and the linear fibers S1.

  That is, the flat fibers H1 and the linear fibers S1 and the flat fibers H2 and the linear fibers S2 have substantially the same fiber length, and the difference is in the shape (difference between flat or linear). ) Only turned out to be.

[Surface functional group of cellulosic fiber]
First, regarding the surface functional groups of the flat fibers H1 and H2 and the linear fibers S1 and S2, carbon atoms surrounded by solid-line circles in the chemical structural formula shown in FIG. Equivalent), focusing on carbon atoms surrounded by dotted circles (corresponding to symbol T in FIGS. 5 and 6), observation was made with an X-ray photoelectron spectrometer (AXIS-165), and the results are shown in FIG. 4A (linear fibers S2) and B (flat fibers H2), and FIG. 5A (linear fibers S1) and B (flat fibers). H1) and FIG. 6A (linear fibers S2) and B (flat fibers H2) are shown in narrow spectrum diagrams.

In the results of FIGS. 3 to 6, when compared with the presence or absence of acid hydrolysis treatment, the flat fibers H1 and the linear fibers S1 and the flat fibers H2 and the linear fibers S2 have the same spectral characteristics. You can see what is shown. That is, as shown in each spectral characteristic, although C1 _S and O1 _S were detected, the S component and Cl component that were expected to be detected by acid hydrolysis treatment (treatment with sulfuric acid, hydrochloric acid, etc.) It was not detected in this observation.

  Therefore, in the cellulosic fiber, it can be considered that the surface functional group does not change with or without acid hydrolysis treatment, and the acid hydrolysis treatment itself does not affect the crystallization rate. found.

[Specific surface area of cellulose fiber]
The specific surface areas of the flat fibers H1, H2 and the linear fibers S1, S2 were observed by the BET adsorption method (using equipment manufactured by NOVA-4200e Quatachrome), and the results are shown in FIG. As a result, the flat fibers H1 and the linear fibers S1, and the flat fibers H2 and the linear fibers S2 are substantially the same in the flat fibers H1 than the linear fibers S1, although the fiber lengths are substantially the same. It can be seen that the specific surface area is large, and the flat fiber H2 has a larger specific surface area than the linear fiber S2.

  Therefore, when the flat fibers H1 and H2 and the linear fibers S1 and S2 were observed with a SEM (S-3400N manufactured by Hitachi High-Technology Corporation) photograph, FIG. 8A (linear fibers S1) and B (flat fibers) H1) and FIG. 9A (linear fibers S2) and B (flat fibers H2), although the fiber lengths are substantially the same, there is a difference between the linear shape and the flat shape, It was confirmed that there was a difference in fiber width and fiber thickness.

  Therefore, it has been found that in the case of cellulosic fibers, even if the fiber length is substantially the same, the flat one has a larger specific surface area than the linear one.

[Crystalization rate]
First, any of flat fibers H1, H2 and linear fibers S1, S2 is blended with the above-mentioned resin PLA, and kneaded with a batch kneader (labor plast mill manufactured by Toyo Seiki Seisakusho Co., Ltd.) to form a pellet. Each of the composition samples was prepared. And about each composition sample, the isothermal crystallization speed | velocity | rate was observed with DSC method (equipment made from TA company), and the result was shown in FIG. As observation conditions, 40 ° C. to 200 ° C. (temperature increase rate 10 ° C./min) was held for 10 minutes, and then 90 ° C. to 130 ° C. (temperature decrease rate 45 ° C./min) was held for 30 minutes.

  As shown in FIG. 10, regardless of which fiber H1, H2, S1, or S2 is used, the crystallization peak time appears even though the crystallization peak time appears around 105 ° C. It can be seen that there is a difference in itself.

  That is, the crystallization peak time is shorter in the sample using the flat fibers H1 than in the sample using the linear fibers S1, and the sample using the flat fibers H2 is shorter than the sample using the linear fibers S2. It can be seen that the crystallization peak time is shortened (each crystallization peak time is shortened by about 20%).

  Therefore, in the case of cellulosic fibers, the crystallization peak time can be shortened by using a flat fiber as compared with the case of using a linear fiber, and the crystallinity of the aliphatic polyester resin composition can be improved. It turns out that it can contribute.

  Although the present invention has been described in detail only for the specific examples described above, it is obvious to those skilled in the art that various changes and modifications are possible within the scope of the technical idea of the present invention. Such variations and modifications are naturally within the scope of the claims.

H1, H2 ... flat fibers S1, S2 ... linear fibers

Claims (3)

A composition obtained by crystallizing a blend containing at least an aliphatic polyester resin and a flat crystal nucleating agent,
The crystal nucleating agent is obtained by cutting the cellulosic fibers not subjected to acid hydrolysis treatment to the fiber length of 140Myuemu～200myuemu, fiber 140Myuemu～200myuemu the cellulosic fibers from being subjected to acid hydrolysis treatment aliphatic polyester resin composition, which is a straight cellulosic fibers and flat cellulosic fibers fiber width is smaller larger fiber thickness compared obtained by cutting the length.   The aliphatic polyester resin composition according to claim 1, wherein the aliphatic polyester resin is polylactic acid.   The aliphatic polyester resin composition according to claim 1 or 2, wherein the flat cellulosic fiber has a fiber width of 20 µm and a fiber thickness of 1.5 to 2.5 µm.