JP6532204B2 - Polyamide resin composition - Google Patents

Description

  The present invention relates to a polyamide resin composition and surface treated calcium carbonate.

  Conventionally, calcium carbonate is compounded in resin for various purposes. For example, Patent Document 1 discloses a polyamide composition using calcium carbonate as an inorganic filler for improving the mechanical physical properties of polyamide.

  Further, in Patent Document 2, calcium carbonate having an average particle diameter in the range of 0.1 to 0.5 μm and an alkylaryl sulfonic acid or a salt thereof surface-treated is blended in a polyamide to obtain impact resistance, etc. It is disclosed to improve the characteristics of

JP, 2011-68871, A JP, 2013-79346, A

  On the other hand, in the polyamide resin composition, there is a demand to improve the friction and wear characteristics.

  An object of the present invention is to provide a surface-treated calcium carbonate which can be blended with a polyamide resin composition and a polyamide resin composition having improved friction and wear characteristics to improve the friction and wear characteristics.

The polyamide-based resin composition of the present invention is a polyamide-based resin composition containing 10 to 25% by volume of surface-treated calcium carbonate, and the surface-treated calcium carbonate contains 80% by mass or more of saturated fatty acid having 16 or more carbon atoms. Surface treatment with fatty acid, BET specific surface area is 20 to 60 m ² / g, and the treatment amount (parts by mass) of the surface treating agent with respect to 100 parts by mass of calcium carbonate is 1 m ² / g of BET specific surface area of calcium carbonate before surface treatment It is characterized in that it is within the range of 0.12 to 0.25.

The surface-treated calcium carbonate of the present invention is surface-treated with a fatty acid containing 80% by mass or more of a saturated fatty acid having 16 or more carbon atoms, and has a BET specific surface area of 20 to 60 m ² / g. Is characterized in that the amount (parts by mass) of is within the range of 0.12 to 0.25 per 1 m ² / g of BET specific surface area of calcium carbonate before surface treatment.

  It is preferable that content of the unsaturated fatty acid contained in the said fatty acid is 10 mass% or less.

  According to the present invention, the friction and wear characteristics of the polyamide resin composition can be improved.

It is a figure which shows the relationship of the compounding quantity of the surface treatment calcium carbonate in the polyamide-type resin composition of an Example and a comparative example, and a friction coefficient. It is a figure which shows the relationship between the compounding quantity of the surface treatment calcium carbonate in the polyamide-type resin composition of an Example and a comparative example, and a specific abrasion rate.

  Hereinafter, the present invention will be described in more detail.

(Calcium carbonate)
The calcium carbonate used in the present invention is not particularly limited, and conventionally known calcium carbonate can be used. Specific examples of calcium carbonate include synthetic calcium carbonate, natural calcium carbonate (heavy calcium carbonate) and the like. In the present invention, synthetic calcium carbonate is preferably used.

  The synthetic calcium carbonate is not particularly limited. As synthetic calcium carbonate, for example, precipitated (colloidal) calcium carbonate, light calcium carbonate and the like can be mentioned. In the present invention, precipitated calcium carbonate is preferably used.

  Synthetic calcium carbonate can be produced, for example, by reacting calcium hydroxide with carbon dioxide gas. Calcium hydroxide can be produced, for example, by reacting calcium oxide with water. Calcium oxide can be produced, for example, by calcining limestone ore with coke or the like. In this case, since carbon dioxide gas is generated at the time of firing, calcium carbonate can be produced by reacting the carbon dioxide gas with calcium hydroxide.

The BET specific surface area of calcium carbonate before the surface treatment is preferably such a value that the BET specific surface area of calcium carbonate after the surface treatment is 20 to 60 m ² / g. Specifically, the BET specific surface area of calcium carbonate before the surface treatment is preferably in the range of ^{20 to} 70 m ² / g.

(Surface treated calcium carbonate)
The surface-treated calcium carbonate of the present invention can be obtained by surface-treating the above-mentioned calcium carbonate with a fatty acid containing 80% by mass or more of a saturated fatty acid having 16 or more carbon atoms. By using a fatty acid in which the content of the saturated fatty acid having 16 or more carbon atoms is 80% by mass or more, the friction and abrasion properties of the polyamide resin composition can be remarkably improved.

  It is preferable that it is 10 mass% or less, and, as for content of the unsaturated fatty acid contained in the said fatty acid, it is more preferable that it is 5 mass% or less. By using such a fatty acid, generation of volatile gas of unsaturated fatty acid at the time of melt-kneading and molding can be suppressed, and contamination of the processing machine can be prevented.

The BET specific surface area of the surface-treated calcium carbonate of the present invention is in the range of 20 to 60 m ² / g. By setting it in such a range, it is possible to remarkably improve the friction and wear characteristics of the polyamide resin composition containing surface treated calcium carbonate. More preferably, the BET specific surface area of the surface-treated calcium carbonate is in the range of 22 to 45 m ² / g. By being in such a range, the friction and wear characteristics can be further improved.

The treatment amount (parts by mass) of the surface treatment agent with respect to 100 parts by mass of calcium carbonate of the present invention is in the range of 0.12 to 0.25 per 1 m ² / g of BET specific surface area of calcium carbonate before the surface treatment. It is inside. By setting it in such a range, it is possible to remarkably improve the friction and wear characteristics of the polyamide resin composition containing surface treated calcium carbonate. Even if the surface treatment amount exceeds 0.25, the effect associated with the increase in the surface treatment amount can not be obtained, which is not preferable from the economical point of view. The more preferable surface treatment amount is in the range of 0.15 to 0.24, and more preferably in the range of 0.18 to 0.22. By being in these ranges, the friction and wear characteristics can be further improved.

  The surface treatment method may be wet treatment in which a surface treatment agent is added to an aqueous suspension (slurry) of calcium carbonate, or calcium carbonate powder and the surface treatment agent are mixed by stirring. It may be dry processing.

  In the case of wet treatment, it is generally preferred to treat the surface treatment agent by adding it to the calcium carbonate water suspension in the form of an alkali metal salt such as Na salt or K salt or in the form of an acid. Therefore, it is preferable to add in the form of Na salt or K salt of fatty acid, or in the form of fatty acid.

  In the case of dry processing, it is generally preferred to add in the form of an acid. Therefore, it is preferable to add as a fatty acid. At the time of addition, it may be diluted with a solvent or the like and added.

(Polyamide resin)
As the polyamide-based resin used in the present invention, conventionally known polyamide-based resins can be used. Specific examples of the polyamide resin include 6 nylon, 66 nylon, 11 nylon, 12 nylon, aromatic nylon, 4T nylon, 6T nylon, 9T nylon and the like.

(Polyamide resin composition)
The polyamide resin composition of the present invention contains 10 to 25% by volume of the above surface-treated calcium carbonate. By setting the content of the surface-treated calcium carbonate in the polyamide resin composition to such a range, excellent friction and wear characteristics can be obtained. If the content of the surface-treated calcium carbonate exceeds 25% by volume, it may be difficult to blend the surface-treated calcium carbonate into the polyamide resin, and the excellent friction and wear characteristics may not be obtained. . The content of surface-treated calcium carbonate is preferably 10 to 20% by volume. By being in such a range, the friction and wear characteristics can be further improved.

  The method for producing the polyamide resin composition of the present invention is not particularly limited. As a method of producing the polyamide resin composition of the present invention, for example, a method of mixing a polyamide resin and surface treated calcium carbonate and heat curing it, dissolving the polyamide resin in a solvent and then surface treating calcium carbonate And a method of mixing surface-treated calcium carbonate with a heated melt of a polyamide-based resin, a method of adding surface-treated calcium carbonate as a master batch, and the like.

  When the polyamide resin is melt-kneaded in the method for producing a polyamide resin composition of the present invention, a kneader generally used can be used. For example, a single-screw or multi-screw kneading extruder, a roll, a Banbury mixer, a pressure kneader, etc. can be used. Among these, a twin-screw extruder equipped with a side feeder equipment is most preferably used. The kneading conditions are not particularly limited. The kneading temperature may be, for example, a temperature higher by 1 ° C. to 100 ° C. than the melting point or the softening point determined by differential scanning calorimetry (DSC) measurement according to JIS K7121.

  The polyamide resin composition of the present invention may contain appropriate known additives as long as the object of the present invention is not impaired. As such additives, for example, antioxidants, heat stabilizers, weathering (light) stabilizers, releasing (lubricant) agents, crystal nucleating agents, inorganic fillers, conductive agents, thermoplastic resins, thermoplastic elastomers And pigments.

  Hereinafter, specific examples according to the present invention will be described, but the present invention is not limited to these examples.

<Production of surface-treated calcium carbonate>
Example 1
As calcium carbonate, synthetic calcium carbonate having a BET specific surface area of 25 m ² / g was used. The shape of this synthetic calcium carbonate is a substantially cubic shape, and the crystal form is a calcite crystal. The synthetic calcium carbonates of the following examples and comparative examples are the same in shape and crystal form.

  A 10% by mass aqueous suspension (slurry) of this calcium carbonate was prepared, and mixed fatty acid sodium A (sodium stearate 66% by mass, sodium palmitate 31% by mass, sodium mytilylate) was prepared in this aqueous calcium carbonate suspension. 2% by mass, 1% by mass of unsaturated fatty acid (oleic acid sodium) 1% by mass) was added to a treatment amount of 5 parts by mass with respect to 100 parts by mass of calcium carbonate.

After the addition, the mixture was stirred for 15 minutes, then filtered and dried to obtain surface-treated calcium carbonate. The BET specific surface area of the obtained surface-treated calcium carbonate was 22 m ² / g. Therefore, the processing amount (parts by mass) of the surface treatment agent was 0.20 per 1 m ² / g of BET specific surface area of calcium carbonate before the surface treatment.

(Example 2)
As calcium carbonate, synthetic calcium carbonate having a BET specific surface area of 25 m ² / g was used.

  A 10% by mass aqueous suspension (slurry) of this calcium carbonate is prepared, and to this calcium carbonate aqueous suspension, 3.2 parts by mass of the same fatty acid as in Example 1 with respect to 100 parts by mass of calcium carbonate Was added to achieve a throughput of

After the addition, the mixture was stirred for 15 minutes, then filtered and dried to obtain surface-treated calcium carbonate. The BET specific surface area of the obtained surface-treated calcium carbonate was 23 m ² / g. Therefore, the processing amount (parts by mass) of the surface treatment agent was 0.13 per 1 m ² / g of BET specific surface area of calcium carbonate before the surface treatment.

(Example 3)
As calcium carbonate, synthetic calcium carbonate having a BET specific surface area of 55 m ² / g was used.

  A 10% by mass aqueous suspension (slurry) of this calcium carbonate is prepared, and the same fatty acid as in Example 1 is treated with this calcium carbonate aqueous suspension in 11 parts by mass with respect to 100 parts by mass of calcium carbonate. It added so that it might become quantity.

After the addition, the mixture was stirred for 15 minutes, then filtered and dried to obtain surface-treated calcium carbonate. The BET specific surface area of the obtained surface-treated calcium carbonate was 51 m ² / g. Therefore, the processing amount (parts by mass) of the surface treatment agent was 0.20 per 1 m ² / g of BET specific surface area of calcium carbonate before the surface treatment.

(Comparative example 1)
As calcium carbonate, synthetic calcium carbonate having a BET specific surface area of 18 m ² / g was used.

  A 10% by mass aqueous suspension (slurry) of this calcium carbonate is prepared, and to this calcium carbonate aqueous suspension, 1.5 parts by mass of the same fatty acid as in Example 1 with respect to 100 parts by mass of calcium carbonate Was added to achieve a throughput of

After the addition, the mixture was stirred for 15 minutes, then filtered and dried to obtain surface-treated calcium carbonate. The BET specific surface area of the obtained surface-treated calcium carbonate was 17 m ² / g. Therefore, the processing amount (parts by mass) of the surface treatment agent was 0.08 per 1 m ² / g of BET specific surface area of calcium carbonate before the surface treatment.

(Comparative example 2)
As calcium carbonate, synthetic calcium carbonate having a BET specific surface area of 18 m ² / g was used.

  A 10% by mass aqueous suspension (slurry) of this calcium carbonate is prepared, and to this calcium carbonate aqueous suspension, the same fatty acid as in Example 1 is added in an amount of 3.6 parts by mass with respect to 100 parts by mass of calcium carbonate. Was added to achieve a throughput of

After the addition, the mixture was stirred for 15 minutes, then filtered and dried to obtain surface-treated calcium carbonate. The BET specific surface area of the obtained surface-treated calcium carbonate was 16 m ² / g. Therefore, the processing amount (parts by mass) of the surface treatment agent was 0.20 per 1 m ² / g of BET specific surface area of calcium carbonate before the surface treatment.

(Comparative example 3)
As calcium carbonate, synthetic calcium carbonate having a BET specific surface area of 25 m ² / g was used.

  A 10% by mass aqueous suspension (slurry) of this calcium carbonate is prepared, and to this calcium carbonate aqueous suspension, the same fatty acid as in Example 1 is treated with 2 parts by mass with respect to 100 parts by mass of calcium carbonate. It added so that it might become quantity.

After the addition, the mixture was stirred for 15 minutes, then filtered and dried to obtain surface-treated calcium carbonate. The BET specific surface area of the obtained surface-treated calcium carbonate was 23 m ² / g. Therefore, the processing amount (parts by mass) of the surface treatment agent was 0.08 per 1 m ² / g of BET specific surface area of calcium carbonate before the surface treatment.

(Comparative example 4)
As calcium carbonate, synthetic calcium carbonate having a BET specific surface area of 75 m ² / g was used.

  A 10% by mass aqueous suspension (slurry) of this calcium carbonate is prepared, and to this calcium carbonate aqueous suspension, the same fatty acid as in Example 1 is treated with 14 parts by mass with respect to 100 parts by mass of calcium carbonate. It added so that it might become quantity.

After the addition, the mixture was stirred for 15 minutes, then filtered and dried to obtain surface-treated calcium carbonate. The BET specific surface area of the obtained surface-treated calcium carbonate was 67 m ² / g. Therefore, the processing amount (parts by mass) of the surface treatment agent was 0.20 per 1 m ² / g of BET specific surface area of calcium carbonate before the surface treatment.

(Comparative example 5)
As calcium carbonate, synthetic calcium carbonate having a BET specific surface area of 25 m ² / g was used.

  A 10% by mass aqueous suspension (slurry) of this calcium carbonate was prepared, and mixed fatty acid sodium B (sodium stearate 34%, sodium palmitate 29% by mass sodium mytilylate) was prepared in this aqueous calcium carbonate suspension. 7% by mass, 15% by mass of sodium laurate and 15% by mass of unsaturated fatty acid (oleic acid sodium) were added to a treatment amount of 5 parts by mass with respect to 100 parts by mass of calcium carbonate.

After the addition, the mixture was stirred for 15 minutes, then filtered and dried to obtain surface-treated calcium carbonate. The BET specific surface area of the obtained surface-treated calcium carbonate was 22 m ² / g. Therefore, the processing amount (parts by mass) of the surface treatment agent was 0.20 per 1 m ² / g of BET specific surface area of calcium carbonate before the surface treatment.

<Preparation of Polyamide Resin Composition>
The polyamide-based resin composition was prepared by adding the surface-treated calcium carbonates of the examples and comparative examples obtained above to the polyamide resin as follows.

  Surface-treated calcium carbonate is contained in a polyamide resin (polyamide 66, manufactured by DuPont, grade: Zytel 101L) so that the content of surface-treated calcium carbonate is 1% by volume, 5% by volume, 10% by volume and 20% by volume The four resin compositions formulated in Specifically, a polyamide resin and calcium carbonate are mixed in a predetermined ratio, vacuum dried at 90 ° C. for 12 hours, and then melt-kneaded at 270 ° C. at a screw speed of 85 rpm using a twin-screw extrusion kneader A polyamide resin composition containing treated calcium carbonate was prepared.

<Measurement of friction coefficient and specific wear rate>
Using the injection molding machine, the polyamide resin composition prepared by the above method was used to prepare a test piece of 30 × 30 × 3 mm. The injection molding conditions were a temperature of 270 ° C., a mold temperature of 100 ° C., and an injection rate of 6 cm ³ / sec. Before molding, the polyamide resin composition was dried at 90 ° C. for 12 hours using a vacuum dryer.

  For measurement of the coefficient of friction and the specific wear rate, a ring on plate type sliding wear tester (FEM-III-E: manufactured by ORIENTEC Co., Ltd.) was used. As the measurement conditions, a ring having an inner diameter of 20 mm and an outer diameter of 25.6 mm made of S45C was used as a mating material, and the sliding speed was 0.5 m / s, the test load was 100 N, and the sliding distance was 3000 m.

The measurement results are shown in Table 1. The unit of the coefficient of friction is mu, the unit of the specific wear rate is _{^{X10 -5 V S (mm 3 /}} N · m).

  Moreover, the result of Table 1 is shown in FIG.1 and FIG.2.

As shown in Table 1 and FIGS. 1 and 2, the polyamide resin composition containing 10 to 25% by volume of surface-treated calcium carbonate of Examples 1 to 3 according to the present invention has a low coefficient of friction and a low specific wear rate. It can be seen that it exhibits excellent friction and wear characteristics.

Claims (2)

A polyamide resin composition comprising 10 to 25% by volume of surface-treated calcium carbonate,
The surface-treated calcium carbonate is surface-treated with a fatty acid containing 80% by mass or more of a saturated fatty acid having 16 or more carbon atoms, and has a BET specific surface area of 20 to 60 m ² / g. The polyamide resin composition whose quantity (parts by mass) is in the range of 0.12 to 0.20 per 1 m ² / g of BET specific surface area of calcium carbonate before surface treatment. The polyamide-based resin composition according to claim 1, wherein the content of unsaturated fatty acid contained in the fatty acid is 10% by mass or less.

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