JP5926024B2 - Polyamide resin composition and method for producing polyamide resin composition - Google Patents

Description

  The present invention relates to a polyamide resin composition having improved mechanical properties and heat resistance, and a method for producing the resin composition.

  Resin compositions in which polyamide resin is reinforced with an inorganic filler such as glass fiber or carbon fiber are widely known. However, these reinforcing materials have a problem that mechanical properties and heat resistance are not improved unless they are blended in a large amount, and a problem that the mass of the resulting resin composition increases due to high specific gravity. In addition, there was a lack of affinity with polyamide.

  Moreover, the molded object which consists of a resin composition obtained using glass fiber, carbon fiber, etc. as a reinforcing material has a problem that warpage becomes large.

  In recent years, cellulose has been used as a reinforcing material for resin materials. Cellulose includes those obtained from trees, those obtained from non-wood resources such as rice, cotton, kenaf and hemp, and bacterial cellulose produced by microorganisms. Cellulose is present in large quantities on the earth. . Cellulose is excellent in mechanical properties. By containing this in the resin, an effect of improving the properties of the resin composition is expected.

  As a method for incorporating cellulose into the thermoplastic resin, a method of melt-mixing the resin and cellulose is common. However, in this method, it is impossible to obtain a resin composition in which cellulose is mixed in a resin in a state where the cellulose is aggregated and cellulose is uniformly dispersed. For this reason, the characteristic of a resin composition cannot fully be improved.

  For example, Patent Document 1 discloses a composite material including cellulose pulp fibers in a thermoplastic plastic, and a polyamide resin is also described as the thermoplastic plastic. In this invention, in order to make it easy to mix a cellulose pulp fiber with a polymer material, it is described that it is granulated using a rotary knife cutter or the like. However, Patent Document 1 describes that when the fiber length is shortened by making it granular, the reinforcing force by adding cellulose pulp fibers is reduced, and therefore the average length of cellulose pulp fibers is 0.1 to 6 mm. Preferred is described.

Furthermore, in the invention described in the cited document 1, cellulose pulp fibers are mixed in a large amount in a thermoplastic plastic, and in the examples, cellulose pulp fibers are added in a large amount of 30% by mass.
And in invention of the cited reference 1, when mixing a cellulose pulp fiber with a polymer material, after making a cellulose pulp fiber dry, it melt-mixes.
From the above, in the invention described in Cited Document 1, the problem of aggregation of cellulose pulp fibers has not been solved, and since the amount of cellulose pulp fibers added is large, a temperature of 230 to 240 ° C. at the time of injection molding Then, the problem of coloring due to decomposition of cellulose also occurred.

Patent Document 2 describes a thermoplastic plastic containing 0.01 to 20 parts by weight of cellulose fiber in 100 parts by weight of plastic. It is described that the cellulose fiber is a viscose fiber, and preferably has a fiber length of 50 μm to 5 mm or a fiber diameter of 1 to 500 μm. In the invention described in Patent Document 2, although the cellulose fiber content is smaller than that of the invention described in Patent Document 1, the fiber length and fiber diameter of the cellulose fiber are large, and a method of containing the cellulose fiber Only the method of melt mixing is shown.
Therefore, even in the invention described in Patent Document 2, the above-described problem of aggregation of cellulose fibers has not been solved.

Patent Document 3 describes a composite composition containing a fibrous filler and a flaky inorganic material. Further, it is described that the composite composition may contain a thermoplastic resin as another constituent component.
However, in the invention described in the cited document 3, only specific examples of the composite composition consisting only of the fibrous filler and the flaky inorganic material are shown, and the composite composition in the case of containing a thermoplastic resin is shown. Neither manufacturing method nor characteristic value is disclosed at all.

JP-T-2002-527536 Japanese National Patent Publication No. 9-505329 JP 2010-285573 A

  The present invention solves the above problems, and the polyamide resin composition in which the cellulose fibers and the layered silicate are uniformly dispersed without aggregation in the polyamide resin, and the mechanical properties and heat resistance are improved. It aims at providing the manufacturing method of a resin composition.

The inventors of the present invention have arrived at the present invention as a result of intensive studies to solve the above problems. That is, the gist of the present invention is as follows.
(1) 0.01-100 parts by mass of cellulose fibers and 0.01-100 parts by mass of layered silicate with respect to 100 parts by mass of polyamide resin , wherein the layered silicate is a swellable fluoromica A polyamide resin composition.
(2) The polyamide resin composition as described in (1) whose average fiber diameter of a cellulose fiber is 10 micrometers or less.
(3) The linear expansion coefficient in the MD direction (which calculates an average value in the region of 20 to 150 ° C.) is 45 × 10 ⁻⁶ (1 / ° C.) or less, according to (1) or (2) Polyamide resin composition.
(4) A method for producing the polyamide resin composition according to any one of (1) to ( 3) , comprising a monomer constituting the polyamide resin, an aqueous dispersion of cellulose fibers, and a layered silicate. A method for producing a polyamide resin composition comprising mixing and conducting a polymerization reaction.
(5) A method for producing the polyamide resin composition according to any one of (1) to ( 3) , wherein a monomer constituting the polyamide resin, an aqueous dispersion of cellulose fibers, and a layered silicate are mixed. And a method for producing a polyamide resin composition, wherein the polymerization reaction is carried out in a state where 0.001 to 5 mol% of an acid having a pKa of 0 to 6 is present with respect to a monomer constituting the polyamide resin.

The polyamide resin composition of the present invention contains cellulose fibers and layered silicate, and the cellulose fibers and layered silicate are uniformly dispersed in the resin composition without agglomeration. Mechanical properties such as expansion coefficient and heat resistance are improved. For this reason, the polyamide resin composition of the present invention can obtain various molded articles by molding methods such as injection molding, extrusion molding, and foam molding, and can be used for various applications.
In addition, since the cellulose fiber and the layered silicate are not contained in the polyamide resin in an aggregated state by the production method of the polyamide resin composition of the present invention, the cellulose fiber and the layered silicate are uniformly dispersed. The polyamide resin composition of the invention can be obtained. For this reason, it becomes possible to improve the mechanical characteristics and heat resistance of the polyamide resin composition even if the content of the cellulose fiber and the layered silicate is relatively small.

Hereinafter, the present invention will be described in detail.
The polyamide resin used in the present invention refers to a polymer having an amide bond formed from an amino acid, lactam or diamine and a dicarboxylic acid.

Examples of monomers that form such a polyamide resin include 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, paraaminomethylbenzoic acid, and the like.
Examples of the lactam include ε-caprolactam and ω-laurolactam.

  Examples of diamines include tetramethylene diamine, hexamethylene diamine, nonane methylene diamine, decane methylene diamine, undecamethylene diamine, dodecane methylene diamine, 2,2,4- / 2,4,4-trimethylhexamethylene diamine, and 5-methyl. Nonamethylenediamine, 2,4-dimethyloctamethylenediamine, metaxylylenediamine, paraxylylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethyl Cyclohexane, 3,8-bis (aminomethyl) tricyclodecane, bis (4-aminocyclohexyl) methane, bis (3-methyl-4-aminocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl) propane, Bis (aminopropyl) Perazine, and an amino ethyl piperazine.

  Dicarboxylic acids include adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5- Examples include sodium sulfoisophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, and diglycolic acid.

  More specifically, the polyamide resin used in the present invention includes polycaproamide (nylon 6), polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), polyhexamethylene sebaca. Mido (nylon 610), polyhexamethylene dodecane (nylon 612), polyundecane methylene adipamide (nylon 116), polyundecanamide (nylon 11), polydodecanamide (nylon 12), polytrimethylhexamethylene terephthalamide (Nylon TMHT), polyhexamethylene terephthalamide (nylon 6T), polyhexamethylene isophthalamide (nylon 6I), polyhexamethylene terephthalamide / isophthalamide (nylon 6T / 6I), polybis (4-aminocyclohexane) Syl) methane dodecamide (nylon PACM12), polybis (3-methyl-4-aminocyclohexyl) methane dodecamide (nylon dimethyl PACM12), polymetaxylylene adipamide (nylon MXD6), polynonamethylene terephthalamide (nylon 9T) , Polydecamethylene terephthalamide (nylon 10T), polyundecamethylene terephthalamide (nylon 11T), polyundecamethylene hexahydroterephthalamide (nylon 11T (H)), and these copolymers and mixtures. May be. Among them, particularly preferred polyamide resins are nylon 6, nylon 66, nylon 11, nylon 12, and copolymers and mixtures thereof.

  Next, the cellulose fiber in this invention is demonstrated. Cellulose fibers include those derived from wood, rice, cotton, hemp, kenaf, abaca, bagasse and the like, as well as those derived from organisms such as bacterial cellulose, valonia cellulose, and squirt cellulose. Also included are regenerated cellulose, cellulose derivatives and the like.

  By including cellulose fibers, the polyamide resin composition of the present invention is improved in mechanical properties such as strength and linear expansion coefficient and heat resistance. In order to sufficiently improve the mechanical properties and heat resistance of the resin composition, it is necessary to uniformly disperse the cellulose fibers in the resin without aggregating the cellulose fibers. For that purpose, the dispersibility of the cellulose fiber to the polyamide resin and the affinity between the polyamide resin and the cellulose fiber are important. Further, in order to make the cellulose fiber have properties such as hydroxyl groups as much as possible, it is important to increase the surface area of the cellulose fiber. For this reason, it is preferable to use cellulose fibers as fine as possible.

  Therefore, in the present invention, it is preferable to use a cellulose fiber having an average fiber diameter of 10 μm or less, among which the average fiber diameter is preferably 500 nm or less, more preferably 300 nm or less. Preferably it is 100 nm or less. Cellulose fibers having an average fiber diameter exceeding 10 μm cannot increase the surface area of the cellulose fibers, and it becomes difficult to improve the dispersibility and affinity for the polyamide resin and the monomers forming the polyamide resin. The lower limit of the average fiber diameter is not particularly limited, but is preferably 4 nm or more in consideration of the productivity of cellulose fibers.

  As such cellulose fibers having an average fiber diameter of 10 μm or less (hereinafter sometimes referred to as cellulose fibers (A)), those obtained by microfibrillation by tearing cellulose fibers are preferable. Various pulverizing apparatuses such as a ball mill, a stone mill, a high-pressure homogenizer, and a mixer can be used as means for microfibrillation. As a cellulose fiber, what is marketed can use "Serish" by Daicel Finechem, for example.

  Moreover, the aggregate of the cellulose fiber taken out as a waste thread can also be used in the manufacturing process of the textiles using a cellulose fiber as a cellulose fiber (A). The production process of the textile product includes spinning, woven fabric, nonwoven fabric production, and other textile product processing. Since these cellulose fiber aggregates are scrap fibers after the cellulose fibers have undergone these steps, the cellulose fibers are refined.

  Further, as the cellulose fiber (A), bacterial cellulose produced by bacteria can be used, and for example, those produced using an Acetobacter group acetic acid bacterium as a producing bacterium can be used. Plant cellulose is the one in which molecular chains of cellulose converge and is formed by bundling very thin microfibrils, whereas cellulose produced from acetic acid bacteria originally has a width of 20 to 50 nm. It is in the form of a ribbon, and forms an extremely fine network compared to plant cellulose.

In this invention, the measuring method of the average fiber diameter of the cellulose fiber contained in the resin composition is as follows. Using a frozen ultramicrotome, a 100 nm-thick section was collected from the resin composition (or a molded article made of the resin composition), stained with OsO ₄ (osmium tetroxide), and then transmission electron microscope (JEOL). Observation is performed using JEM-1230). The length in the direction perpendicular to the longitudinal direction of the cellulose fiber (single fiber) is measured from the electron microscope image. At this time, the maximum length in the vertical direction is taken as the fiber diameter. Similarly, the fiber diameter of 10 cellulose fibers (single fibers) is measured, and the average value of 10 fibers is calculated as the average fiber diameter.
In addition, about the thing with a large fiber diameter of a cellulose fiber, a stereomicroscope (OLYMPUS SZ-) which cut | disconnected the 10 micrometers section | slice with the microtome, or left the resin composition (or molded object which consists of resin compositions) as it is. 40), the fiber diameter is measured from the obtained image in the same manner as described above, and the average fiber diameter is obtained.

Moreover, the length of the cellulose fiber contained in the resin composition in the present invention can be determined when measuring the average fiber diameter as described above, and the cellulose fiber (single fiber) in the electron microscope image can be obtained. The length in the longitudinal direction. Then, similarly to the fiber diameter, the length of 10 cellulose fibers (single fibers) is measured, and the average value of 10 is calculated as the average fiber length.
The cellulose fiber in the present invention preferably has an aspect ratio (average fiber length / average fiber diameter) which is a ratio of the above-described average fiber diameter and average fiber length of 10 or more, particularly 50 or more, more preferably 100 or more. Preferably there is. When the aspect ratio is 10 or more, the mechanical properties of the polyamide resin composition are easily improved, the strength is higher, and the linear expansion coefficient can be reduced.
The polyamide resin composition of the present invention can be uniformly dispersed in the resin even when the cellulose fiber (A) has an aspect ratio of 100 or more by being obtained by the production method of the present invention as described later. Is possible.

And content of the cellulose fiber in the polyamide resin composition of this invention needs to be 0.01-50 mass parts with respect to 100 mass parts of polyamide resins, and 0.05-30 mass parts especially It is preferable that it is 0.1-20 mass parts, More preferably, it is 0.1-10 mass parts. When the content of the cellulose fiber is less than 0.01 parts by mass with respect to 100 parts by mass of the polyamide resin, the effect of containing the cellulose fiber as described above, that is, the effect of improving mechanical properties and heat resistance is achieved. I can't.
On the other hand, when the content of the cellulose fiber exceeds 50 parts by mass with respect to 100 parts by mass of the polyamide resin, it becomes difficult to contain the cellulose fiber in the resin composition, or the obtained resin composition is injection molded. If heat treatment is performed at a high temperature during molding, discoloration occurs.

  By obtaining the polyamide resin composition of the present invention by the production method of the present invention as described later, even if the cellulose fiber content is small, it is uniformly dispersed in the polyamide resin. The composition can provide sufficient mechanical properties and an effect of improving heat resistance. That is, even if the cellulose fiber content is in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the polyamide resin, the obtained polyamide resin composition has high strength and low linear expansion coefficient. In addition to excellent mechanical properties, it also has excellent heat resistance.

  Next, the layered silicate in the present invention will be described. In the present invention, by including the layered silicate in the polyamide resin, mechanical properties such as strength and linear expansion coefficient and heat resistance are improved. In order to sufficiently improve the mechanical properties and heat resistance of the resin composition, it is necessary to uniformly disperse the layered silicate in the resin without aggregation. For this purpose, the dispersibility of the layered silicate with respect to the polyamide resin and the affinity between the polyamide resin and the layered silicate are important.

Examples of the layered silicate used in the present invention include natural smectite, vermiculite, and synthetic swellable fluoromica. Of these, swellable fluorine mica is preferable because of its excellent dispersibility and affinity in the polyamide resin.
Examples of smectites include montmorillonite, beidellite, hectorite, and saponite. Examples of the swellable fluorine mica include Na-type fluorine tetrasilicon mica, Na-type teniolite, Li-type teniolite, and the like.

The swellable fluorine mica as described above is represented by the following formula.
αMF · β (aMgF ₂ · bMgO) · γSiO ₂
Here, M represents sodium or lithium, α, β, γ, a and b each represents a coefficient, 0.1 ≦ α ≦ 2, 2 ≦ β ≦ 3.5, 3 ≦ γ ≦ 4, 0 ≦ a ≦ 1, 0 ≦ b ≦ 1 and a + b = 1.

  The swellable fluoromica in the present invention is preferably obtained by using talc as a starting material and intercalating alkali ions therein. In this method, alkali silicofluoride or alkali fluoride is mixed with talc and heat-treated in a magnetic crucible at 700 to 1200 ° C. for a short time to obtain a swellable fluorine mica. The swellable fluoromica used in the present invention is particularly preferably produced by this method.

  The amount of alkali silicofluoride or alkali fluoride to be mixed with talc is preferably 10 to 35% by mass of the mixture, and if it is out of this range, the production rate of swellable fluorine mica decreases.

  In order to obtain the swellable fluorine mica, the alkali metal of alkali silicofluoride or alkali fluoride is preferably sodium or lithium. These alkali metals may be used alone or in combination. Among alkali metals, potassium is not preferred because swellable fluorinated mica cannot be obtained, but it can be used in combination with sodium or lithium, and for the purpose of adjusting swellability in a limited amount. is there.

  In the present invention, the swelling property means that the fluorine mica absorbs polar molecules or cations such as aminocarboxylic acid, nylon salt, water molecule, etc. between the layers, so that the distance between layers is increased, or further, the swelling is cleaved, resulting in ultrafineness. It means the property of forming particles, and the fluorine mica represented by the above formula exhibits such swelling properties.

  In addition, since swellable fluoromica is excellent in dispersibility and affinity in polyamide resin, the side thickness is 101 μm or less, the thickness is 0.1 μm or less, and the layer thickness in the C-axis direction measured by the X-ray powder method Is preferably 9 to 20 mm.

And the layered silicate in the polyamide resin composition of this invention needs to contain 0.01-100 mass parts with respect to 100 mass parts of polyamide resins, and 0.1-20 mass parts especially Furthermore, it is preferable that 1-10 mass parts is contained.
When the content with respect to 100 parts by mass of the polyamide resin is less than 0.01 parts by mass, the effect of improving the mechanical properties and heat resistance cannot be achieved. On the other hand, when the content with respect to 100 parts by mass of the polyamide resin exceeds 100 parts by mass, it becomes difficult to add and polymerize the layered silicate, and a resin composition cannot be obtained. Moreover, even if it is obtained by melt-kneading with a polyamide resin, the resulting resin composition has a large decrease in toughness.

Since the polyamide resin composition of the present invention contains a specific amount of cellulose fibers and layered silicate, the effects of each of the cellulose fibers and layered silicate are further combined with mechanical properties such as strength and linear expansion coefficient. And heat resistance is further improved.
The polyamide resin composition of the present invention preferably has a number average molecular weight of 10,000 to 100,000. When the number average molecular weight is less than 10,000, the mechanical properties of the resin composition are lowered, which is not preferable. On the other hand, when the number average molecular weight exceeds 100,000, the moldability of the resin composition is rapidly lowered, which is not preferable. The number average molecular weight is a value determined in terms of PMMA at 40 ° C. using hexafluoroisopropanol as an eluent using a gel permeation chromatography (GPC) apparatus equipped with a differential refractive index detector.

Cellulose fibers have a very high affinity with water, and the smaller the average fiber diameter, the better the dispersion state with respect to water. Further, when water is lost, cellulose fibers are strongly aggregated by hydrogen bonding, and once aggregated, it becomes difficult to achieve a dispersion state similar to that before aggregation. In particular, this tendency becomes more prominent as the average fiber diameter of the cellulose fibers decreases.
Therefore, the cellulose fiber is preferably combined with the polyamide resin in a state containing water.

  Moreover, by polymerizing the monomer in the presence of the monomer constituting the polyamide resin and the layered silicate, the swellable fluorine mica is sufficiently finely dispersed in the polyamide, and the effects of the present invention are remarkably exhibited.

  Therefore, as a method for producing the polyamide resin composition of the present invention, when the polyamide resin is obtained by a polymerization reaction, a monomer constituting the polyamide resin, an aqueous dispersion of cellulose fibers, and a layered silicate are mixed, and a polymerization reaction is performed. It is preferable to adopt the method of performing. By such a production method, it becomes possible to obtain a polyamide resin composition in which cellulose fibers and layered silicate are uniformly dispersed without agglomeration. In particular, a resin composition having improved mechanical properties and heat resistance can be obtained. it can. And even if the content of cellulose fiber and layered silicate is small, since it is uniformly dispersed in the polyamide resin in a sufficiently dispersed state, the polyamide resin composition has sufficient mechanical properties. And heat resistance can be improved. That is, even if the content (total amount) of the cellulose fiber and the layered silicate is in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the polyamide resin, the polyamide resin composition is strong and elastic. In addition to excellent mechanical properties such as rate and linear expansion coefficient, it also has excellent heat resistance.

  Therefore, the polyamide resin composition of the present invention is preferably obtained by mixing a monomer constituting the polyamide resin, an aqueous dispersion of cellulose fibers, and a layered silicate, and performing a polymerization reaction. .

  Moreover, there exists heat deformation temperature as a parameter | index which shows that the polyamide resin composition of this invention is excellent in heat resistance. The polyamide resin composition of the present invention preferably has a heat deformation temperature of 150 ° C. or higher at a load of 1.8 MPa, more preferably 155 ° C. or higher, and more preferably 160 ° C. or higher. When the heat distortion temperature at a load of 1.8 MPa is less than 150 ° C., the heat resistance is not sufficient and it is difficult to use for various applications.

  The polyamide resin composition of the present invention preferably has a heat distortion temperature of 200 ° C. or higher at a load of 0.45 MPa, more preferably 202 ° C. or higher, and more preferably 204 ° C. or higher. If the heat distortion temperature at a load of 0.45 MPa is less than 200 ° C., it does not have sufficient heat resistance and becomes difficult to use for various applications.

  In addition, the thermal deformation temperature in this invention is measured based on ASTM D648 using the same thing as the test piece produced when measuring the bending strength and bending elastic modulus mentioned later. At this time, the load is measured at 1.8 MPa and 0.45 MPa.

  The polyamide resin composition of the present invention is also excellent in mechanical properties. As an index indicating mechanical properties, there are a linear expansion coefficient and strength.

The polyamide resin composition of the present invention preferably has a coefficient of linear expansion in the MD direction of 40 × 10 ⁻⁶ (1 / ° C.) or less, particularly 38 × 10 ⁻⁶ (1 / ° C.) or less. More preferably, it is preferably 35 × 10 ⁻⁶ (1 / ° C.) or less. When the linear expansion coefficient in the MD direction exceeds 40 × 10 ⁻⁶ (1 / ° C.), the dimensional stability tends to be inferior and it is difficult to use for various applications.

  In addition, the linear expansion coefficient in this invention is measured based on JIS K7197 using the thing similar to the test piece produced when measuring bending strength and bending elastic modulus mentioned later, and is 20-150 degreeC. The average value in the area is calculated. Further, the flow direction of the resin at the time of molding is defined as MD direction, and the direction perpendicular to the flow is defined as TD direction.

  The polyamide resin composition of the present invention preferably has a bending strength of 150 MPa or more, more preferably 155 MPa or more, and more preferably 160 MPa or more. If the bending strength is less than 150 MPa, it does not have sufficient strength, and it becomes difficult to use it for various purposes.

  Furthermore, the polyamide resin composition of the present invention preferably has a flexural modulus of 4.0 GPa or more, more preferably 4.5 GPa or more, and even more preferably 5.0 GPa or more. If the flexural modulus is less than 4.0 GPa, the flexibility is poor and the rigidity becomes too strong, so even if the bending strength is within the above range, the versatility is poor and it is not practically preferable.

The bending strength and the flexural modulus in the present invention are measured at 23 ° C. based on ASTM D790 using a test piece obtained under the following injection molding conditions.
(Injection molding conditions)
The polyamide resin composition is molded by using an injection molding machine (IS-80G type, manufactured by Toshiba Machine Co., Ltd.) using an ASTM standard 1/8 inch three-point bending test piece mold, and length x width x A specimen having a thickness of 127 mm (5 inches) × 12.7 mm (1/2 inch) × 3.2 mm (1/8 inch) is obtained.

Next, the manufacturing method of the polyamide resin composition of this invention is demonstrated.
In the method for producing a polyamide resin composition of the present invention, a monomer constituting the polyamide resin, an aqueous dispersion of cellulose fibers, and a layered silicate are mixed to perform a polymerization reaction. The aqueous dispersion of cellulose fibers in the production method of the present invention is obtained by dispersing cellulose fibers in water, and the content of cellulose fibers in the aqueous dispersion may be 0.01 to 50% by mass. preferable. Such an aqueous dispersion can be obtained by stirring purified water and cellulose fibers with a mixer or the like.

  And the aqueous dispersion of cellulose fiber, the monomer which comprises a polyamide resin, and layered silicate are mixed, and it is set as a uniform dispersion by stirring with a mixer etc. Thereafter, the dispersion is heated, and the temperature is raised to 150 to 270 ° C., followed by a polymerization reaction by stirring. At this time, water in the aqueous dispersion can be discharged by gradually discharging water vapor when the dispersion is heated. And after completion | finish of a polymerization reaction, after paying out the obtained resin composition, it is preferable to cut | disconnect and pelletize.

  When bacterial cellulose is used as the cellulose fiber, an aqueous dispersion of cellulose fiber that is obtained by immersing bacterial cellulose in purified water and replacing the solvent may be used. When using a solvent-substituted bacterial cellulose, after the solvent replacement, the concentration is adjusted to a predetermined level, and then mixed with the monomer constituting the layered silicate and the polyamide resin, and the polymerization reaction proceeds in the same manner as described above. preferable.

Thus, in the manufacturing method of this invention, a cellulose fiber will be used for a polymerization reaction in a state with favorable dispersibility by using for a polymerization reaction with an aqueous dispersion. Furthermore, the cellulose fibers subjected to the polymerization reaction are improved in dispersibility by agitation with the monomer and water during the polymerization reaction and by stirring at the above temperature conditions, and the fibers aggregate. It is possible to obtain a resin composition in which cellulose fibers having a small average fiber diameter are well dispersed. As described above, according to the production method of the present invention, the dispersibility of the cellulose fiber is improved, so that it is contained in the resin composition after the completion of the polymerization reaction, rather than the average fiber diameter of the cellulose fiber added before the polymerization reaction. The cellulose fiber that is present may have a smaller average fiber diameter or fiber length.
Further, in the production method of the present invention, the step of drying the cellulose fiber is not necessary, and the production can be performed without the step of causing the scattering of fine cellulose fibers, so that the polyamide resin composition can be obtained with good operability. It becomes possible. In addition, since it is not necessary to replace water with an organic solvent for the purpose of uniformly dispersing the monomer, the layered silicate, and cellulose, it is possible to excel in handling and to suppress the discharge of chemical substances during the manufacturing process.

Furthermore, in the production method of the present invention, during the polymerization reaction, a monomer constituting the polyamide resin, an aqueous dispersion of cellulose fibers and a layered silicate are mixed, and an acid having a pKa of 0 to 6 is used as a monomer constituting the polyamide resin. It is preferable to carry out the polymerization reaction in a state of 0.001 to 5 mol% based on the amount. Thereby, an ion exchange reaction between a cation and a monomer contained in the layered silicate clay is performed, and there is an effect that nano-dispersion in polyamide is promoted.
At this time, a predetermined amount of an aqueous solution of layered silicate and acid (dissolved in water used as a polymerization initiator to form an aqueous solution) is added to the monomer constituting the polyamide, under conditions according to the normal polymerization of polyamide. What is necessary is just to superpose | polymerize. When swellable fluoromica is used as the layered silicate, it is not necessary to carry out the swelling treatment in advance, and it may be added to the monomer as it is. The pressure at the time of polymerization does not need to be high, and the pressure at the time of suppression may be about 10 kg / cm ² at the highest.

  The acid used in the present invention has a pKa in the range of 0-6. An acid having a pKa of more than 6 has a small amount of proton emission, so that the above effect is poor. On the other hand, when the pKa is less than 0, there is a problem such as corrosion of the polymerization kettle during continuous production, which is inappropriate. The acid having a pKa in the range of 0 to 6 may be an inorganic acid or an organic acid. Specifically, benzoic acid, sebacic acid, formic acid, acetic acid, nitrous acid, phosphoric acid, phosphorous acid, etc. Derivatives acting as these acids such as chloroacetic acid, trichloroacetic acid, trifluoroacetic acid and the like can be mentioned.

  The addition amount of the acid is 0.001 to 5 mol% with respect to the nylon monomer, and preferably 0.1 to 2.0 mol%. When the amount is less than 0.001 mol%, the above effect becomes poor. On the other hand, when the addition amount of the acid exceeds 5 mol%, it becomes difficult to obtain a polymer having a high degree of polymerization.

  The molar amount of the acid to be added is obtained by dividing the difference between the acid equivalent of the whole system and the amine equivalent by the valence of the acid to be added.

  In the polyamide resin composition of the present invention, the pigment, heat stabilizer, antioxidant, weathering agent, plasticizer, lubricant, mold release agent, antistatic agent, impact agent, A flame retardant, a compatibilizing agent and the like may be contained.

  Further, the polyamide resin composition of the present invention may contain a polymer other than the polyamide resin as long as the characteristics are not significantly impaired. Examples of other polymers include polyolefins, polyesters, polycarbonates, polystyrenes, polymethyl (meth) acrylates, poly (acrylonitrile-butadiene-styrene) copolymers, liquid crystal polymers, and polyacetals.

  In addition, the polyamide resin composition of this invention can be made into various molded objects by molding methods, such as injection molding, blow molding, extrusion molding, and foam molding. That is, a molded body formed by injection molding, or a film or sheet formed by extrusion molding, a molded body processed from these films or sheets, or a hollow body formed by blow molding, and the hollow body A molded body processed from the above, a fiber obtained by melt spinning, and the like.

  Specific examples of these molded products include personal computer casing parts and casings, mobile phone casing parts and casings, other office equipment casing parts, resin parts for electrical appliances such as connectors; bumpers, instrument panels, Resin parts for automobiles such as console boxes, garnishes, door trims, ceilings, floors, panels around engines, etc., agricultural materials such as containers and cultivation containers, and plastic parts for agricultural machinery; Resin parts; Tableware and food containers such as dishes, cups and spoons; Medical resin parts such as syringes and drip containers; Resin parts for drains, fences, storage boxes, construction switchboards, etc .; Resin parts for greening materials such as bricks and flower pots; Resin parts for leisure and miscellaneous goods such as cooler boxes, fan fans and toys; ballpoint pens, rulers, clicks Stationery resin component and the like; fibers knitting weaving to obtain woven or knitted fabric or nonwoven fabric, and the like.

Hereinafter, the present invention will be described more specifically with reference to examples. In addition, the measuring method of the various characteristic values in an Example is as follows.
[Bending modulus, bending strength]
Using the obtained polyamide resin composition (pellet), the measurement was performed by the method described above.
[Heat deformation temperature (HDT)]
Using the obtained polyamide resin composition (pellet), the measurement was performed by the method described above.
[Linear expansion coefficient]
Using the obtained polyamide resin composition (pellet), the measurement was performed by the method described above.
[Average fiber diameter of cellulose fibers]
The average fiber diameter of the cellulose fiber in the obtained polyamide resin composition was measured and calculated by the above method.

Example 1
As an aqueous dispersion of cellulose fibers, serisch KY100G (manufactured by Daicel Finechem Co., Ltd .: containing 10% by mass of cellulose fibers having an average fiber diameter of 125 nm) was added to this, and purified water was added thereto, followed by stirring with a mixer. An aqueous dispersion having a fiber content of 3% by mass was prepared.
Further, as the layered silicate, swellable fluorine mica (manufactured by Corp Chemical Chemical Co., Ltd .: ME-100) was used.
170 parts by mass of an aqueous dispersion of cellulose fibers, 254 parts by mass of ε-caprolactam, 2.5 parts by mass of layered silicate (swelling fluoromica) and 0.25 parts by mass of phosphorous acid (0 with respect to ε-caprolactam .14 mol%) was stirred and mixed with a mixer until a uniform solution was obtained. Subsequently, the mixed solution was heated to 240 ° C. with stirring, while gradually releasing the water vapor to be boosted from 0 kgf / cm ² to a pressure of 7 kgf / cm ^2. Thereafter, the pressure was released to atmospheric pressure, and a polymerization reaction was carried out at 240 ° C. for 1 hour. When the polymerization was completed, the resin composition obtained was dispensed and cut into pellets. The obtained pellets were treated with hot water at 95 ° C., scoured and dried.
The injection molding conditions for obtaining a test piece used for measuring the bending strength and the like were a cylinder temperature of 260 ° C. and a mold temperature of 80 ° C.

Example 2
A polyamide resin composition was obtained in the same manner as in Example 1 except that the addition amount of the swellable fluorine mica was 5.1 parts by mass.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Example 3
A polyamide resin composition was obtained in the same manner as in Example 1 except that the amount of swellable fluoromica added was 10.2 parts by mass.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Example 4
A polyamide resin composition was obtained in the same manner as in Example 1 except that the addition amount of the swellable fluorine mica was 2.5 parts by mass and the addition amount of the aqueous dispersion of cellulose fibers was 425 parts by mass.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Example 5
A polyamide resin composition was obtained in the same manner as in Example 4 except that the amount of the swellable fluoromica added was 5.1 parts by mass.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Example 6
A polyamide resin composition was obtained in the same manner as in Example 2 except that the amount of the cellulose fiber aqueous dispersion added was 850 parts by mass.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Example 7
A polyamide resin composition was obtained in the same manner as in Example 2 except that the amount of the cellulose fiber aqueous dispersion added was changed to 1700 parts by mass.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Example 8
A polyamide resin composition was obtained in the same manner as in Example 1 except that the addition amount of the swellable fluoromica was 25.5 parts by mass.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Example 9
A polyamide resin composition was obtained in the same manner as in Example 1 except that the amount of the swellable fluorine mica added was 51 parts by mass.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Example 10
As cellulose fibers, serisch KY100G (manufactured by Daicel Finechem Co., Ltd .: containing 10% by mass of cellulose fibers having an average fiber diameter of 125 nm) was freeze-dried and then pulverized to obtain powdered cellulose.
For 100 parts by mass of nylon 6 (Unitika BRL number average molecular weight 17000), 2 parts by mass of the obtained powdery cellulose and layered silicate [swelling fluorinated mica (Coop Chemical Chemical Co., Ltd .: ME-100) are used. did. ] 1.0 parts by mass blended, supplied to a twin screw extruder (PCM-30 manufactured by Ikegai Co., Ltd.) having a screw diameter of 30 mm and an average groove depth of 2.5 mm, barrel temperature of 240 ° C., screw rotation speed of 120 rpm, Melt kneading was conducted at a residence time of 2.7 minutes. The resin composition obtained by melt kneading was dispensed and cut into pellets. The obtained pellets were molded as they were and various physical properties were measured.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Example 11
Pellets were obtained by melt-kneading in the same manner as in Example 10 except that the amount of swellable fluorine mica added was 2.0 parts by mass.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Example 12
Pellets were obtained by melt-kneading in the same manner as in Example 10 except that the amount of the swellable fluorine mica added was 4.0 parts by mass.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Comparative Example 1
A polyamide resin composition was obtained in the same manner as in Example 1 except that neither the layered silicate nor the aqueous dispersion of cellulose fiber was added.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Comparative Example 2
A polyamide resin composition was obtained in the same manner as in Example 1 except that the layered silicate was not added and the content of the aqueous dispersion of cellulose fibers was 85 parts by mass.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Comparative Example 3
A polyamide resin composition was obtained in the same manner as in Example 1 except that the layered silicate was not added and the content of the aqueous dispersion of cellulose fibers was 170 parts by mass.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Comparative Example 4
A polyamide resin composition was obtained in the same manner as in Example 1 except that the layered silicate was not added and the content of the aqueous dispersion of cellulose fibers was 340 parts by mass.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Comparative Example 5
A polyamide resin composition was obtained in the same manner as in Example 1 except that the aqueous dispersion of cellulose fiber was not added.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Comparative Example 6
A polyamide resin composition was obtained in the same manner as in Example 2 except that the aqueous dispersion of cellulose fiber was not added.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Comparative Example 7
A polyamide resin composition was obtained in the same manner as in Example 3 except that the aqueous dispersion of cellulose fibers was not added.
The injection molding conditions for obtaining a test piece used for measurement of bending strength and the like were the same as in Example 1.

Comparative Example 8
The same procedure as in Example 1 was conducted except that the addition amount of the aqueous dispersion of cellulose fiber was 4250 parts by mass and the addition amount of phosphorous acid was 4.25 parts by mass (0.14 mol% with respect to ε-caprolactam). Attempts were made to polymerize the polyamide resin composition, but the cellulose was agglomerated, making stirring difficult, and white spots could be visually confirmed, and polymerization was not possible.

Comparative Example 9
Polymerization of the polyamide resin composition was attempted in the same manner as in Example 1 except that the amount of the swellable fluorine mica added was 267 parts by mass. However, stirring was difficult and polymerization was not possible.

  Table 1 shows the results of measuring the characteristic values of the polyamide resin compositions obtained in Examples 1 to 12 and Comparative Examples 1 to 9.

As is clear from Table 1, the polyamide resin compositions obtained in Examples 1 to 9 were prepared by mixing a cellulose fiber, an aqueous dispersion of layered silicate, and a monomer constituting the polyamide resin, and performing a polymerization reaction. Since it was obtained, fine cellulose fibers and layered silicate were uniformly dispersed in the polyamide resin without agglomeration. For this reason, the polyamide resin compositions obtained in Examples 1 to 9 are all excellent in heat resistance, have high bending elastic modulus and bending strength, and have a low MD coefficient of linear expansion and excellent mechanical properties. It was. In particular, with respect to the linear expansion coefficient, a higher effect was observed when they were used together during polymerization than when each was added alone.
Moreover, since the polyamide resin composition obtained in Examples 10-12 is what the cellulose fiber and layered silicate were contained in the polyamide resin by melt-kneading, the polyamide resin obtained in Examples 1-9 Compared to the composition, the heat resistance, linear expansion coefficient, bending strength, and flexural modulus were all inferior. However, it was superior in all these performances to the polyamide resin compositions obtained in Comparative Examples 5 to 7 containing no cellulose fiber.
On the other hand, since the polyamide resin composition obtained in Comparative Example 1 did not contain both cellulose fibers and layered silicate, the heat resistance, linear expansion coefficient, bending strength, and bending elastic modulus were inferior. . Moreover, since the polyamide resin composition obtained in Comparative Examples 2 to 7 contained only one of cellulose fibers and layered silicate, it was more heat resistant than the resin compositions of Examples containing both. , Linear expansion coefficient, flexural modulus, and bending strength were all inferior. Moreover, in Comparative Examples 8-9, since there was too much addition amount of a cellulose fiber or a layered silicate, the viscosity raise remarkably, it became difficult to stir and it was not able to superpose | polymerize.

Claims (5)

A polyamide comprising 0.01 to 50 parts by weight of cellulose fibers and 0.01 to 100 parts by weight of a layered silicate with respect to 100 parts by weight of a polyamide resin , wherein the layered silicate is a swellable fluoromica Resin composition. The polyamide resin composition of Claim 1 whose average fiber diameter of a cellulose fiber is 10 micrometers or less. 3. The polyamide resin composition according to claim 1, wherein a linear expansion coefficient in the MD direction (which calculates an average value in a region of 20 to 150 ° C.) is 45 × 10 ⁻⁶ (1 / ° C.) or less. It is a method for manufacturing the polyamide resin composition in any one of Claims 1-3 , Comprising: The monomer which comprises a polyamide resin, the aqueous dispersion of a cellulose fiber, and layered silicate are mixed, Polymerization reaction A process for producing a polyamide resin composition characterized by comprising: It is a method for manufacturing the polyamide resin composition in any one of Claims 1-3 , Comprising: The monomer which comprises a polyamide resin, the aqueous dispersion of a cellulose fiber, and layered silicate are mixed, pKa is 0. A method for producing a polyamide resin composition, wherein the polymerization reaction is carried out in a state in which 0.001 to 5 mol% of an acid of -6 is present with respect to a monomer constituting the polyamide resin.