JP6823860B2 - Polyamide resin composition, its production method, and a molded product comprising the same. - Google Patents

Description

The present invention relates to a polyamide resin composition, a method for producing the same, and a molded product comprising the same.

Polyamide resin is a crystalline thermoplastic resin having properties such as excellent mechanical strength, thermal stability, moldability, and chemical resistance, and its molded product is in the fields of automobiles, daily necessities, electronic appliances, etc. Widely used in.
In recent years, due to modularization and the like, a resin molded body having a more complicated shape has been required, and at the same time, a shape having a larger number of weld portions has been required for one molded body.

When a polyamide resin composition containing a reinforcing material for improving mechanical strength is molded into a molded body having a welded portion, the mechanical strength is improved in the non-welded portion, but the molten resin compositions are made of gold. In the weld portions that collide with each other in the mold, there is a problem that the strength of the weld portions of the molded product of the polyamide resin alone without the reinforcing material is lower than the strength of the weld portions.
By the way, in recent years, a large molding machine has been used in order to mass-produce a molded body. In the molding of a small molded product using a large molding machine, the molten resin stays in the molding machine for a long time. Due to the long-term residence in this molten state, a part of the resin is decomposed, and the generated gas causes a problem that the strength of both the non-welded portion and the welded portion of the molded product is lowered.

In order to solve the problem that the strength of the weld portion is lowered, for example, Patent Documents 1 to 3 disclose a method of blending a higher fatty acid metal salt into a resin composition, and a short molding cycle using a small molding machine is disclosed. In the molding of the above, the desired weld strength is obtained. However, when the resin composition is molded by being retained in a molding machine for a long time, there is a problem that the amount of gas generated is large and the strength of the non-welded portion and the welded portion of the molded product is lowered.

Japanese Unexamined Patent Publication No. 2008-266497 Japanese Unexamined Patent Publication No. 11-42666 Japanese Unexamined Patent Publication No. 2011-195790

The problem of the present invention is that the mechanical strength can be improved by blending the reinforcing material even in the weld portion, and even when the molten resin stays in the molding machine for a long time, the decrease in the strength of the weld portion is suppressed. Is to provide a polyamide resin composition which can be used.

As a result of intensive studies to solve the above problems, the present inventors have found that the polyamide resin composition containing the reinforcing material contains a polyamide having a mass reduction rate during heating within a specific range. Further, they have found that the above problems can be solved by containing a specific amount of talc, and have reached the present invention.
That is, the gist of the present invention is as follows.
(1) A polyamide resin composition containing 100 parts by mass of polyamide (A), 0.1 to 100 parts by mass of reinforcing material (B), and 0.1 to 5 parts by mass of talc (C).
Ri mass reduction rate of the polyamide (A) is 3.0% by mass or less when the polyamide resin composition was heated for 60 minutes at 0.99 ° C. / min at 330 ° C. After the temperature was raised to 330 ° C.,
The polyamide resin composition, an inert gas atmosphere, a polyamide resin composition which tensile strength of the weld portion is characterized in der Rukoto than 75MPa injection molded test piece with a residence time of 300 seconds.
(2) The polyamide resin composition according to (1), wherein the weight reduction rate of the polyamide (A) is 2.0% by mass or less.
(3) A method for producing the polyamide resin composition according to (1) above.
Polymerization of the polyamide (A) and melt-kneading of the polyamide (A), the reinforcing material (B) and the talc (C) were carried out in an inert gas atmosphere.
In the melt-kneading of polyamide (A), reinforcing material (B) and talc (C), one or more side feeders are installed in the melt-kneader, and the amount of talc (C) added per side feeder is determined by the polyamide (A). A) A method for producing a polyamide resin composition, which comprises adding talc (C) from a side feeder so as to be 1 part by mass or less with respect to 100 parts by mass.
(4) In the melt-kneading of the polyamide (A), the reinforcing material (B) and the talc (C), the reinforcing material (B) is added from a plurality of locations excluding the base of the melt-kneader (3). The method for producing a polyamide resin composition according to the above .
(5 ) A molded product obtained by molding the polyamide resin composition according to (1) or (2) above.
( 6 ) A welded portion-containing molded product obtained by molding the polyamide resin composition according to (1) or (2) above.
( 7 ) A sliding member including the weld portion-containing molded body according to ( 6 ) above.
( 8 ) A machine tool provided with the sliding member described in ( 7 ) above.

According to the present invention, the mechanical strength of the weld portion is improved by blending the reinforcing material, and even when the molten resin is retained in the molding machine for a long time, the decrease in the strength of the weld portion is suppressed. You can get a body. The molded product of the polyamide resin composition of the present invention can be used for mechanical parts having high weld strength and machines having sliding portions using the same.

Hereinafter, the present invention will be described in detail.
The polyamide resin composition of the present invention contains a polyamide (A), a reinforcing material (B) and a talc (C).
In the present invention, the polyamide (A) preferably has a low melting point. When the melting point of the polyamide (A) exceeds 350 ° C., the decomposition temperature of the amide bond is about 350 ° C., so that carbonization and decomposition proceed during the melt processing, and the retention stability and the strength of the weld portion are significantly lowered. There is.

Examples of the polyamide (A) include aliphatic polyamides, semi-aromatic polyamides, alicyclic polyamides, and copolymers thereof according to the classification of the monomer components.
Specific examples of the aliphatic polyamide include polyamide 6, polyamide 66, and polyamide 46.
Examples of the semi-aromatic polyamide include a polyamide composed of an aromatic dicarboxylic acid component and an aliphatic diamine component, and specific examples thereof include polyamide 4I (I: isophthalic acid), polyamide 6I, and polyamide 7T (T: terephthalic acid). ), Polyamide 8T, Polyamide 9T, Polyamide 10T, Polyamide 11T, Polyamide 12T and the like.
Specific examples of the alicyclic polyamide include polyamide 6C (C: 1,4-cyclohexanedicarboxylic acid), polyamide 7C, polyamide 8C, polyamide 9C, polyamide 10C, polyamide 11C, and polyamide 12C.
Further, as the copolymer, for example, when the number of carbon atoms of the diamine is 6, PA6T / 6, PA6T / 12, PA6T / 66, PA6T / 610, PA6T / 612, PA6T / 6I, PA6T / 6I / 66, PA6T / M5T (M5: Methylpentadiamine), PA6T / TM6T (TM6: 2,2,4- or 2,4,4-trimethylhexamethylenediamine), PA6T / MMCT (MMC: 4,4'-methylenebis (2-methyl) Cyclohexylamine)) and the like.
As the polyamide (A), these polyamides may be used alone, or a copolymer or a mixture of two or more kinds of polyamides may be used.
In the present invention, as the polyamide (A), polyamide 46, polyamide 6T, polyamide 9T, polyamide 10T, and copolymers thereof are mentioned as suitable examples because of their high industrial versatility. Further, the polyamide 6T, the polyamide 9T, the polyamide 10T, and their copolymers can be applied to the mechanical parts which are the intended uses of the polyamide from the viewpoint of high heat resistance and high strength. Of these, polyamide 10T and its copolymer are particularly preferable.

In the present invention, the polyamide (A) preferably contains a monocarboxylic acid component as a constituent component. By containing the monocarboxylic acid, the polyamide (A) can keep the amount of free amino groups at the terminals low, and the decomposition gas of the polyamide due to thermal deterioration and oxidative deterioration when receiving heat can be suppressed. As a result, there is an effect of improving the retention stability and the strength of the welded portion, and eventually improving the strength of the sliding member.

The content of the monocarboxylic acid component is preferably 0.3 to 4.0 mol%, preferably 0.3 to 3.0 mol%, based on all the monomer components constituting the polyamide (A). Further preferably, it is more preferably 0.3 to 2.5 mol%, and particularly preferably 0.8 to 2.5 mol%. By containing the monocarboxylic acid component within the above range, the polyamide (A) can suppress decomposition gas due to thermal deterioration and oxidative deterioration when it receives heat, and can reduce the molecular weight distribution during polymerization. The mold releasability during molding is improved, and discoloration during disassembly can be suppressed. On the other hand, when the content of the monocarboxylic acid component of the polyamide (A) exceeds the above range, the mechanical properties of the polyamide (A) may deteriorate. In the present invention, the content of the monocarboxylic acid refers to the ratio of the residue of the monocarboxylic acid in the polyamide (A), that is, the monocarboxylic acid desorbed from the terminal hydroxyl group.

In the present invention, the molecular weight of the monocarboxylic acid component is preferably 140 or more, and more preferably 170 or more. When the molecular weight of the monocarboxylic acid of the polyamide (A) is 140 or more, decomposition gas due to thermal deterioration and oxidative deterioration when receiving heat is suppressed, mold releasability is improved, and discoloration during decomposition is achieved. It can be suppressed and the molding fluidity can be improved.
Examples of the monocarboxylic acid component include aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, and aromatic monocarboxylic acids, and among them, aliphatic monocarboxylic acids are preferable.
Examples of the aliphatic monocarboxylic acid having a molecular weight of 140 or more include caprylic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid. Of these, stearic acid is preferable because of its high versatility.
Examples of the alicyclic monocarboxylic acid having a molecular weight of 140 or more include 4-ethylcyclohexanecarboxylic acid, 4-hexylcyclohexanecarboxylic acid, and 4-laurylcyclohexanecarboxylic acid.
Examples of aromatic monocarboxylic acids having a molecular weight of 140 or more include 4-ethylbenzoic acid, 4-hexylbenzoic acid, 4-laurylbenzoic acid, 1-naphthoic acid, 2-naphthoic acid and derivatives thereof. ..
The monocarboxylic acid component may be used alone or in combination. Further, a monocarboxylic acid having a molecular weight of 140 or more and a monocarboxylic acid having a molecular weight of less than 140 may be used in combination.
In the present invention, the molecular weight of the monocarboxylic acid refers to the molecular weight of the raw material monocarboxylic acid.

In general, it is known that a polymer has a crystalline phase and an amorphous phase, and crystal properties such as melting point are determined solely by the state of the crystalline phase. Since the terminal groups in the polymer are present in the amorphous phase, the melting point of the polyamide does not change depending on the presence or absence and type of the terminal groups. Since the monocarboxylic acid bonded to the end of the polyamide chain is also present in the amorphous phase, the melting point of the polyamide does not decrease due to the inclusion of the monocarboxylic acid.

In the present invention, the melt flow rate (MFR) of the polyamide (A) is preferably 1 to 150 g / 10 minutes, more preferably 1 to 50 g / 10 minutes, and 5 to 15 g / 10 minutes. Is even more preferable. The MFR can be used as an index of molding fluidity, and the higher the MFR value, the higher the fluidity. If the MFR of the polyamide (A) exceeds 150 g / 10 minutes, the mechanical properties of the obtained resin composition may deteriorate, and the amount of volatile substances may also increase. On the other hand, if the MFR of the polyamide (A) is less than 1 g / 10 minutes, the fluidity is extremely low and melt processing may not be possible.

The polyamide (A) can be produced by using a conventionally known method of heat polymerization method or solution polymerization method. Among them, the heat polymerization method is preferably used because it is industrially advantageous. The polymerization of the polyamide (A) is preferably carried out in an inert gas atmosphere by enclosing an inert gas such as nitrogen, carbon dioxide or argon in a polymerization kettle. This has the effect of suppressing the generation of gas generated during heating due to thermal deterioration and oxidative deterioration of the polyamide during polymerization, and at the same time, suppressing the generation of volatile low molecular weight products in the process after polymerization.

In the production of the polyamide (A), a polymerization catalyst may be used to increase the efficiency of polymerization. Examples of the polymerization catalyst include phosphoric acid, phosphite, hypophosphorous acid or salts thereof, and the amount of the polymerization catalyst added is usually 2 mol% or less based on the total mol of dicarboxylic acid and diamine. Is preferable.

The polyamide resin composition of the present invention needs to contain a reinforcing material (B).
As the reinforcing material (B), for example, fibrous reinforcing materials such as glass fiber, potassium titanate fiber, alumina fiber, silica fiber, zirconia fiber, silicon carbide fiber, ceramic fiber, wallastnite, sepiolite, and attapulsite, and clay minerals. Examples thereof include plate-shaped reinforcing materials such as silica, alumina, and granular reinforcing materials such as glass beads. Among them, from the viewpoint of improving mechanical strength, fibrous reinforcing material is preferable, glass fiber, potassium titanate fiber, wallastnite, sepiolite, and attapulsite are more preferable, and glass fiber and potassium titanate fiber are used in combination with glass fiber. The combined use of wallastnite is preferable.
The glass fiber is preferably surface-treated with a silane coupling agent. Further, it may be surface-treated with a sizing agent in which a silane coupling agent is dispersed. Examples of the silane coupling agent include vinylsilane-based, acrylicsilane-based, epoxysilane-based, and aminosilane-based ones. Aminosilane-based ones are used because the adhesion effect between the polyamide (A) and the glass fiber can be easily obtained. preferable.
The fiber length of the reinforcing material (B) is preferably 0.1 to 7 mm, more preferably 0.5 to 6 mm. The fiber diameter is preferably 3 to 20 μm, more preferably 5 to 13 μm. The reinforcing material (B) having a fiber length of 0.1 to 7 mm and a fiber diameter of 3 to 20 μm can efficiently reinforce the resin composition without adversely affecting the moldability.
The content of the reinforcing material (B) needs to be 1 to 100 parts by mass, preferably 10 to 60 parts by mass, and 20 to 50 parts by mass with respect to 100 parts by mass of the polyamide (A). Is more preferable. If the content of the reinforcing material (B) is less than 1 part by mass, the mechanical strength improving effect may not be obtained, while if it exceeds 100 parts by mass, the reinforcing efficiency of the mechanical strength may decrease. In some cases, workability during melt-kneading may decrease, it may be difficult to obtain pellets of the resin composition, and the amount of decomposed gas may increase due to the shear heat generation effect during kneading.

The polyamide resin composition of the present invention needs to contain talc (C).
The talc (C) may be surface-treated for neutralization, reduction of agglutination action, and improvement of wettability with the polyamide (A). Examples of the surface treatment agent include organic acids such as epoxy-based, amino-based, silicon-based, and fatty acid-based.
The form of talc (C) is not particularly limited, and examples thereof include plate-like, scaly, scaly, and flaky. The average particle size of talc is preferably 0.5 to 60 μm, more preferably 0.5 to 20 μm. If the average particle size is less than 0.5 μm, agglomerates are likely to occur due to poor dispersion, and a uniform molded product may not be obtained and the mechanical properties may deteriorate. On the other hand, if the average particle size exceeds 60 μm, the surface of the molded product may become rough.
Talc can be obtained from Japan Talc, Hayashi Kasei, Fujikura Applied Chemicals, Asada Flour Milling, etc.

The content of talc (C) needs to be 0.1 to 5 parts by mass and preferably 0.1 to 2.0 parts by mass with respect to 100 parts by mass of polyamide (A). When the content of talc (C) is less than 0.1 parts by mass, the strength of the weld portion of the obtained molded product may be low, while when it exceeds 5 parts by mass, the strength of the weld portion and retention Although it is excellent in stability, the mechanical strength of the non-welded portion may be insufficient in the molded product having a short residence time.

The polyamide resin composition of the present invention may further contain an antioxidant.
The content of the antioxidant is preferably 0.05 to 5 parts by mass, and more preferably 0.2 to 5 parts by mass with respect to 100 parts by mass of the polyamide (A). If the content of the antioxidant is less than 0.05 parts by mass, the effect of suppressing decomposition during heating such as during melt kneading and molding is small, and if it exceeds 5 parts by mass, the mold is easily soiled during molding. Molding defects may occur or the decomposition gas of the antioxidant may reduce the strength.
Examples of the antioxidant include phosphorus-based antioxidants, hindered phenol-based antioxidants, hindered amine-based antioxidants, triazine-based compounds, sulfur-based compounds, and phosphinates, and examples thereof include phosphorus-based antioxidants and hinders. Dophenol-based antioxidants and sulfur-based compounds are preferable.

The polyamide resin composition of the present invention needs to have a mass reduction rate of the polyamide (A) of 3.0% by mass or less when heated to 330 ° C. at 150 ° C./min and then heated at 330 ° C. for 60 minutes. It is preferably 2.0% by mass or less. Since the polyamide (A) constituting the polyamide resin composition has a low mass reduction rate due to heating and less generation of decomposition gas due to heating, the weld portion of the obtained molded product is suppressed from being lowered in strength. The strength can be improved by the reinforcing material contained. Further, even when the molten resin stays in the molding machine for a long time, it is possible to suppress a decrease in the weld strength.

As a method for producing the polyamide resin composition of the present invention, a method of blending polyamide (A), reinforcing material (B) and talc (C), other additives and the like, and melt-kneading is preferable.
Examples of the melt-kneading method include a method using a batch kneader such as lavender, a Banbury mixer, a Henschel mixer, a helical rotor, a roll, a single-screw extruder, a twin-screw extruder and the like.
The melt-kneading temperature is selected from the region where the polyamide (A) melts but the polyamide (A) does not decompose. If the melt-kneading temperature is too high, organic components such as polyamide (A), various additives, and surface treatment agents for various additives may decompose, and the strength of the welded and non-welded parts of the obtained molded product may decrease. There is. Assuming that the melting point of the polyamide (A) is Tm, the melt-kneading temperature is preferably (Tm-20 ° C.) to (Tm + 50 ° C.).

In the present invention, talc (C) is added during melt-kneading of the polyamide (A) and the reinforcing material (B) and further melt-kneaded to increase the mass reduction rate of the polyamide (A) during heating. Can be a range.
In the batch type melt kneading, the amount of talc (C) added at one time is 1 part by mass or less with respect to 100 parts by mass of the polyamide (A), and in the continuous type melt kneading, the melt kneader is used. One or more side feeders are installed, and talc (C) is added from the side feeders so that the amount added per side feeder is 1 part by mass or less.
By adding talc in this way, talc can be mixed with good dispersibility to the extent that heat is not generated. When the amount of talc (C) added at one time or at one place exceeds 1 part by mass, the polyamide (A) is likely to undergo thermal decomposition, and the mass reduction rate at the time of heating tends to be high. In the continuous melt-kneading, the side feeder to which talc is added is preferably installed downstream of the kneading portion of the screw in the melt-kneading machine.

Further, the reinforcing material (B) is also divided into a plurality of times or a plurality of places in the polyamide (A) being melt-kneaded so that the amount of the reinforcing material (B) added at one time or at one place is small, similarly to the talc (C). It is preferable to add it. When the reinforcing material (B) is added to the polyamide (A) at once during the melt-kneading of the polyamide (A), the viscosity of the resin composition during the kneading rises sharply because the temperature temporarily drops sharply. Furthermore, a large amount of shear will be applied. As a result, the actual temperature of the resin composition becomes higher than the set temperature of the apparatus, organic components may be decomposed, and volatile substances may be generated in the system.
As a method of adding the reinforcing material (B) to the polyamide (A) in a plurality of times, for example, when a batch type mixer is used as a melt kneader, a method of supplying the reinforcing material (B) in a plurality of times can be mentioned. When a continuous twin-screw extruder is used as the melt-kneader, a method of adding from a plurality of side feeders other than the base (top feeder) of the melt-kneader can be mentioned.

As described above, by adding the talc (C) or the reinforcing material (B) to the polyamide (A) by reducing the amount added at one time or at one place, the actual temperature of the resin composition becomes excessive. It is possible to suppress the increase and the generation of volatile substances due to thermal deterioration and oxidative deterioration during melt kneading.

In the melt-kneading of the polyamide resin composition, an inert gas such as nitrogen, carbon dioxide, or argon is sealed in the entire machine from the raw material supply section to the heating section, and melt-kneaded in an inert gas atmosphere. Is preferable. As a result, decomposition of the polyamide (A) during melt-kneading and organic components such as various surface treatment agents due to oxidative deterioration can be suppressed, and at the same time, decomposition in the steps after melt-kneading can be suppressed.

Examples of the method for processing the polyamide resin composition of the present invention into various shapes include a method of extruding the molten mixture into a strand shape into a pellet shape, a method of hot-cutting and underwater-cutting the molten mixture into a pellet shape, and a method of forming a pellet shape. Examples thereof include a method of extruding into a sheet and cutting, and a method of extruding into a block and pulverizing to form a powder.

Examples of the method for producing a molded product by molding the polyamide resin composition of the present invention include an injection molding method, an extrusion molding method, a blow molding method, and a sintering molding method, which improve mechanical properties and moldability. The injection molding method is preferable because it has a large effect.
The injection molding machine is not particularly limited, and examples thereof include a screw in-line type injection molding machine and a plunger type injection molding machine. The polyamide resin composition heated and melted in the cylinder of the injection molding machine is weighed for each shot, injected into the mold in a molten state, cooled and solidified in a predetermined shape, and then molded from the mold. Taken out. The resin temperature at the time of injection molding is preferably heat-melted at a temperature equal to or higher than the melting point (Tm) of the polyamide (A), and more preferably lower than (Tm + 50 ° C.).
When the polyamide resin composition is heated and melted, it is preferable to use sufficiently dried polyamide resin composition pellets. If the amount of water contained is large, the resin may foam in the cylinder of the injection molding machine, making it difficult to obtain an optimum molded product. The water content of the polyamide resin composition pellets used for injection molding is preferably less than 0.3 parts by mass and more preferably less than 0.1 parts by mass with respect to 100 parts by mass of the polyamide resin composition.

Even during molding, it is preferable that an inert gas such as nitrogen, carbon dioxide, or argon is sealed in the entire area from the raw material supply section to the heating section of the machine base, and the machine is molded in an inert gas atmosphere. As a result, decomposition of the organic components such as the polyamide (A) and various surface treatment agents during molding due to thermal deterioration and oxidative deterioration can be suppressed, and at the same time, decomposition can be suppressed in the steps after the molding step.

The polyamide resin composition of the present invention has excellent low volatility and retention stability when heated, and the molded product obtained by molding the polyamide resin composition has excellent weld strength. The mechanical parts provided with the molded body of the present invention have high strength and can be suitably used for mechanical parts such as machine tools.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

1. 1. Measuring Method The characteristics of the polyamide (A) and the polyamide resin composition were measured and evaluated by the following methods.

(1) Melting point Using a differential scanning calorimeter DSC-7 (manufactured by PerkinElmer), the temperature is raised to 350 ° C at a heating rate of 20 ° C / min, held at 350 ° C for 5 minutes, and the temperature is lowered to 20 ° C / min. The temperature was lowered to 25 ° C., and the temperature was further maintained at 25 ° C. for 5 minutes, and then the top of the heat absorption peak when the temperature was raised again at a heating rate of 20 ° C./min was defined as the melting point (Tm).

(2) Melt flow rate (MFR)
According to JIS K7210, the measurement was carried out at a temperature (melting point + 15 ° C.) and a load of 1.2 kgf.
The MFR can be used as an index of molding fluidity, and the higher the MFR value, the higher the fluidity.

(3) Weight reduction rate The obtained polyamide resin composition was placed in a crucible and heated in a heating furnace at 600 ° C. for 12 hours to incinerate, and the ash content (mass%) of the residue was determined.
Further, the obtained polyamide resin composition was subjected to a differential thermogravimetric simultaneous measurement device (manufactured by SII Nanotechnology, "TG / DTA 7200") at 30 ° C. to 330 ° C. under a nitrogen atmosphere of 200 mL / min. The temperature was raised to 150 ° C./min and TGA measurement was performed. After holding at 330 ° C. and heating for 60 minutes, the reduced mass was determined.
From the mass of the polyamide resin composition used for the TGA measurement, the reduced mass determined by the TGA measurement, and the value of the ash content, the mass reduction rate was determined by the following formula.
Mass reduction rate (%) = (mass reduced in TGA measurement) / {(mass of polyamide resin composition used in TGA measurement) x (1-ash content / 100)}

(4) Mechanical properties Using an injection molding machine S2000i-100B (manufactured by FANUC), the polyamide resin composition was subjected to cylinder temperature (melting point + 15 ° C), mold temperature (melting point-185 ° C), no nitrogen filling, A test piece (dumbbell piece) having a length of 150 mm, a width of 10 mm, and a thickness of 3 mm was produced by injection molding with a two-point gate from both ends under the condition of a residence time of 30 seconds.
Using the obtained test piece, the tensile strengths of the welded portion and the unwelded portion were measured according to ISO527-1.
Since the tensile strength of the weld portion of the polyamide molded product not containing the reinforcing material (B) is 80 MPa (Comparative Example 1), the polyamide resin molded product containing the reinforcing material (B) has a weld portion. The tensile strength is preferably 80 MPa or more, and more preferably 90 MPa or more.
Compared with the tensile strength (180 MPa) of the non-welded portion of the molded product (Comparative Example 2) of the resin composition containing the polyamide (A) and the reinforcing material (B) (ratio 1), the tensile strength of the welded portion (75 MPa) ) (Ratio 2), respectively, the effect of containing talc (C) in the resin composition was evaluated.
Further, a test piece was prepared by changing the residence time of 30 seconds during injection molding to 300 seconds, the tensile strength thereof was measured, and the resin composition was obtained from "ratio 1" and "ratio 2" in the same manner as above. The effect of containing talc (C) in the product was evaluated.

2. 2. Raw Materials The raw materials used in Examples and Comparative Examples are shown below.

(1) Polyamide (A)
-Polyamide (A-1)
4.70 kg of powdered terephthalic acid (TPA) as a dicarboxylic acid component, 0.32 kg of stearic acid (STA) as a monocarboxylic acid component, and 9.3 g of sodium hypophosphate monohydrate as a polymerization catalyst. The mixture was placed in a ribbon blender type reactor, sealed with nitrogen, and heated to 170 ° C. with stirring at a rotation speed of 30 rpm. Then, while keeping the temperature at 170 ° C. and the rotation speed at 30 rpm, 4.98 kg of 1,10-decanediamine (DDA) heated to 100 ° C. as a diamine component using a liquid injection device was added to 2 . Addition was carried out continuously (continuous liquid injection method) over 5 hours to obtain a reaction product. The molar ratio of the raw material monomer is TPA: DDA: STA = 48.5: 49.6: 1.9 (the equivalent ratio of the functional groups of the raw material monomer is TPA: DDA: STA = 49.0: 50.0). : 1.0).
Subsequently, the obtained reaction product was polymerized by heating it in the same reactor under a nitrogen stream at 250 ° C. and a rotation speed of 30 rpm for 8 hours to prepare a polyamide powder.
Then, the obtained polyamide powder was formed into strands using a twin-screw kneader, the strands were passed through a water tank to be cooled and solidified, and the strands were cut with a pelletizer to obtain polyamide (A-1) pellets.

-Polyamide (A-2) to (A-4)
Polyamides (A-2) to (A-4) were obtained in the same manner as the polyamide (A-1) except that the resin composition was changed as shown in Table 1.

-Polyamide (A-5): Polyamide 46 (TW300 manufactured by DSM)
-Polyamide (A-6): Polyamide 66 (A125J manufactured by Unitika Ltd.)

Table 1 shows the resin composition and characteristic values of the above-mentioned polyamides (A-1) to (A-6).

(2) Reinforcing material (B)
B-1: Glass fiber (03JAFT692 manufactured by Asahi Fiber Glass), average fiber diameter 10.5 μm, average fiber length 3 mm
B-2: Milled glass fiber (EPH80MD-10A manufactured by Nippon Electric Glass Co., Ltd.), average fiber diameter 10.5 μm × fiber length 80 μm

(2) Talc (C)
-C-1: Talc (D-800 manufactured by Japan Talc), average particle size 0.8 μm
-C-2: Talc (MW HS-T manufactured by Hayashi Kasei Co., Ltd.), average particle size 4.75 μm

Example 1
100 parts by mass of polyamide (A-1) is weighed using a loss-in weight type continuous fixed quantity feeder (CE-W-1 type manufactured by Kubota Co., Ltd.), and a screw diameter 26 mm, L / C50 isodirectional twin-screw extruder. It was supplied to the main supply port (base) of (Toshiba Machine Co., Ltd. TEM26SS type) and melt-kneaded. Then, 1.0 part by mass of talc (C-1) and 42 parts by mass of glass fiber (B-1) were supplied from the side feeder, and further kneading was performed. The side feeder was installed on the downstream side of the first kneading portion for melting the polyamide (A-1) in the twin-screw extruder in the same direction. In addition, nitrogen gas was conducted from the fixed quantity supply device, the main supply port of the extruder, and the side feeder to maintain the oxygen concentration at 1% or less. The polyamide resin composition was taken into a strand shape from the die, passed through a water tank to be cooled and solidified, and cut with a pelletizer to obtain pellets of the polyamide resin composition. The barrel temperature of the extruder was set (melting point −5 to + 15 ° C.), screw rotation speed 250 rpm, and discharge rate 25 kg / h.

Examples 2-10 , 14-17 , Comparative Examples 1-11 , Reference Examples 1-3
The same operation as in Example 1 was carried out to obtain polyamide resin composition pellets, except that the composition of the polyamide resin composition and the conditions at the time of melt-kneading were changed as shown in Table 2.

Various evaluation tests were carried out using the obtained polyamide resin composition pellets. The results are shown in Table 2.

In the polyamide resin compositions of Examples 1 to 10 and 14 to 17, the mass reduction rate of polyamide was low, and the tensile strength of the weld portion of the obtained molded product was determined by the polyamide-only molded product (Comparative Example 1) or The tensile strength of the weld portion was reduced by the addition of the reinforcing material, which was higher than the tensile strength of the molded product (Comparative Example 2), and in the examples in which nitrogen was sealed during melt kneading or molding, the residence time was as long as 300 seconds. Even so, the decrease in the tensile strength of the welded portion was suppressed, and the retention stability was excellent.
The resin compositions of Examples 1, 6 and 8 containing the polyamides (A-1), (A-2) and (A-4) containing a monocarboxylic acid having a molecular weight of 140 or more have a molecular weight of less than 140. Compared with the resin composition of Example 7 containing the polyamide (A-3) containing a monocarboxylic acid, the mass reduction rate of the polyamide was small, and the obtained molded product had a high tensile strength at the weld portion.
The resin composition of Example 1 containing the polyamide (A-1) containing an aliphatic monocarboxylic acid is the resin composition of Example 7 containing the polyamide (A-3) containing an aromatic monocarboxylic acid. The mass reduction rate of polyamide was smaller than that of the above, and the obtained molded product had high tensile strength at the welded portion.
The resin composition of Example 1 containing the polyamide (A-1) containing 1,10-decanediamine is the resin composition of Example 6 containing the polyamide (A-2) containing 1,9-nonanediamine. It had better mechanical properties than the thing.

The polyamide-only molded product of Comparative Example 1 has the same tensile strength in the non-welded portion and the welded portion. In the molded product of Comparative Example 2 formed by adding a reinforcing material to polyamide, the tensile strength of the non-welded portion was remarkably improved, but the tensile strength of the welded portion was decreased.
In the production of the polyamide resin composition, Comparative Examples 3 and 6 in which talc was added from the base (main supply port), Comparative Example 4 in which talc was added from the base and the side feeder, and the amount of talc added per side feeder. The resin compositions of Comparative Examples 5 and 7 in which the amount of talc exceeded 1 part by mass, Comparative Example 8 in which the amount of talc added exceeded 5 parts by mass, and Comparative Example 9 in which the reinforcing material was added from the base were all polyamides. The tensile strength of the welded portion of the obtained molded product was lower than that of Comparative Examples 1 and 2, and the tensile strength of the welded portion could not be improved.

Claims (8)

A polyamide resin composition containing 100 parts by mass of polyamide (A), 0.1 to 100 parts by mass of reinforcing material (B), and 0.1 to 5 parts by mass of talc (C).
Ri mass reduction rate of the polyamide (A) is 3.0% by mass or less when the polyamide resin composition was heated for 60 minutes at 0.99 ° C. / min at 330 ° C. After the temperature was raised to 330 ° C.,
The polyamide resin composition, an inert gas atmosphere, a polyamide resin composition which tensile strength of the weld portion is characterized in der Rukoto than 75MPa injection molded test piece with a residence time of 300 seconds. The polyamide resin composition according to claim 1, wherein the weight reduction rate of the polyamide (A) is 2.0% by mass or less. A method for producing the polyamide resin composition according to claim 1.
Polymerization of the polyamide (A) and melt-kneading of the polyamide (A), the reinforcing material (B) and the talc (C) were carried out in an inert gas atmosphere.
In the melt-kneading of polyamide (A), reinforcing material (B) and talc (C), one or more side feeders are installed in the melt-kneader, and the amount of talc (C) added per side feeder is determined by the polyamide (A). A) A method for producing a polyamide resin composition, which comprises adding talc (C) from a side feeder so as to be 1 part by mass or less with respect to 100 parts by mass. The polyamide according to claim 3, wherein in the melt-kneading of the polyamide (A), the reinforcing material (B), and the talc (C), the reinforcing material (B) is added from a plurality of locations excluding the base of the melt-kneading machine. A method for producing a resin composition. A molded product obtained by molding the polyamide resin composition according to claim 1 or 2. A welded portion-containing molded product obtained by molding the polyamide resin composition according to claim 1 or 2. A sliding member including the weld portion-containing molded body according to claim 6 . A machine tool comprising the sliding member according to claim 7 .