JPS6152174B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a novel modified polyamide resin with improved impact strength by condensing an olefin polymer having carboxyl groups. In general, polyamide has excellent heat resistance, mechanical strength, and rigidity, so it is widely used as an engineering resin for various mechanical parts materials.
There is a drawback that the strength against impact is poor, and improvement in this point is desired. As a method to meet such demands, for example, it has been proposed to blend an ethylene ionomer into polyamide (U.S. Pat. No. 3,845,163).
It is difficult to adjust the compounding conditions and it is difficult to obtain a sufficiently satisfactory effect, so it is not yet suitable for industrial implementation. The present inventors have conducted intensive research to develop polyamide resins that exhibit high impact resistance in addition to polyamide's good heat resistance, mechanical strength, and rigidity. It was discovered that the purpose could be achieved by modifying the polyamide by adding coalescence and causing a condensation reaction between the amino group of the former and the carboxyl group of the latter, and based on this knowledge, the present invention was made. It came to this. That is, according to the present invention, polyamide 60-95
% by weight and a mixture of 40 to 5% by weight of an olefinic polymer having a carboxyl group, or a mixture thereof
20~100 parts by weight of inorganic filler for reinforcement
After melt-mixing and granulating 200 parts by weight, the resulting granules are heated under vacuum or inert gas flow at the reaction temperature of the terminal amino group and carboxyl group, but at a temperature that does not exceed the melting point of the polyamide. By heating to perform a condensation reaction, a modified polyamide resin having excellent heat resistance, mechanical strength, rigidity, and impact resistance can be obtained. The modified polyamide resin obtained by the present invention is a novel substance with a structure in which the terminal amino group in the polyamide and the carboxyl group in the olefin polymer having a carboxyl group are condensed to form an amide bond between them. It is. The polyamide used in the method of the present invention has an amide bond

It refers to a polymer having the formula, such as nylon-6, nylon-66, nylon-610, nylon-12, and copolymers thereof such as nylon-6/66. Preferably, these polyamides have terminal amino groups of at least 30 milliequivalents/Kg. Further, examples of the olefin polymer having a carboxyl group used in the method of the present invention include a copolymer of an olefin and an unsaturated carboxylic acid,
This copolymer includes a copolymer whose carboxyl groups are partially neutralized with metal ions, an ethylene/vinyl acetate copolymer grafted with an unsaturated carboxylic acid, and a polypropylene grafted with an unsaturated carboxylic acid. I can do it. The unsaturated carboxylic acid unit contained in this olefinic polymer is 0.5
~15 mol%, preferably 1-10 mol%. The ratio of the polyamide component used in the method of the present invention to the olefinic polymer component having carboxyl groups depends on the purpose of use of the modified polyamide resin obtained, but the resistance of polyamide as a normal engineering resin is When the purpose is to improve impact resistance, the range of 60 to 95% by weight of polyamide and 40 to 5% by weight of olefinic polymer having carboxyl groups, especially 75 to 90% by weight of the former and 25 to 10% by weight of the latter.
A weight percent range is preferred. If the proportion of the olefinic polymer having carboxyl groups is less than 5% by weight, the effect of improving impact resistance will be insufficient, and this
If it exceeds 40% by weight, the heat resistance, mechanical strength, and rigidity, which are characteristics of polyamide, will be impaired, which is not preferable. To melt-mix the polyamide and the olefinic polymer having carboxyl groups, any means used for ordinary melt-mixing can be used, but both components can be melt-mixed using a screw extruder, especially a twin-screw extruder. It is industrially most advantageous to melt and mix the two. In the present invention, the thus melted and mixed mixture is granulated into an appropriate shape. Although the shape of the granules may be arbitrary, it is preferable that the granules have a particle size that allows them to be used as a release molding material as they are. Next, while maintaining the shape of the granules thus obtained, condensation is carried out between the terminal amino group of the polyamide and the carboxyl group of the olefinic polymer having a carboxyl group under vacuum or under an inert gas flow. Heat to the temperature at which the reaction occurs. This heating is advantageously carried out, for example using a rotary heating vessel, with vacuum degassing or by passing a preheated inert gas through. The heating temperature depends on the type of raw material,
Although it varies depending on the component composition, it is necessary to maintain the solid state at a temperature below the melting point of the polyamide, and the temperature is usually selected in the range of 120 to 220°C, preferably 160 to 210°C. Note that when a reinforcing inorganic filler is blended into the molten mixture, a higher temperature can be used as desired. Heating time is at least 30 minutes, usually 2 to 10 hours. In the present invention, as described above, the granules of the molten mixture are heated for a predetermined period of time, and this treatment causes a condensation reaction between the terminal amino groups of the polyamide and the carboxyl groups of the olefinic polymer having carboxyl groups to form an amide. A novel modified polyamide resin is produced in which the polyamide and the olefin polymer are chemically bonded to each other through the formation of groups. In the present invention, when a reinforcing inorganic filler is included in the molten mixture, a predetermined ratio of polyamide, an olefinic polymer having a carboxyl group, and the reinforcing inorganic filler are melt-mixed and reacted after granulation. is preferable. Of course, it is also possible to form a modified polyamide resin between a polyamide and an olefin polymer having a carboxyl group, and then add a reinforcing inorganic filler. Examples of reinforcing inorganic fillers used at this time include glass fibers, glass beads, calcium silicate such as wollastonite,
Magnesium silicate represented by talc, aluminum silicate represented by kaolin and clay,
Examples include diatomaceous earth, magnesium phosphate, titanium phosphate, calcium carbonate, calcium sulfate, calcium sulfite, and asbestos. Such a reinforcing inorganic filler can also be used by activating the surface by, for example, treatment with an organic silane compound or an organic borane compound, or by heat treatment. In this case, the usage ratio of each component is in the range of 20 to 200 parts by weight of the reinforcing inorganic filler per 100 parts by weight of the composition of 60 to 95% by weight of polyamide and 40 to 5% by weight of olefinic polymer having carboxyl groups. To be elected. The modified polyamide resin obtained by the present invention exhibits high impact strength without substantially deteriorating the excellent mechanical strength and other characteristics of polyamide. On the other hand, in a simple mixture of polyamide and an olefinic polymer having carboxyl groups, in order to obtain the desired impact resistance, it is necessary to increase the mixing ratio of the olefinic polymer. Strength and other properties will be significantly lower. On the other hand, as mentioned above, the novel modified polyamide resin obtained by the present invention has high impact strength without losing much of the excellent mechanical strength and other characteristics of polyamide because of the components of the olefin polymer. This is thought to be due to the relatively small proportion and the special structure of the modified polyamide resin itself. Generally, melt mixing of a polyamide and an olefinic polymer having a carboxyl group poses no particular problem experimentally, but when done industrially, it partially gels, making long-term continuous production impossible. Furthermore, when gel is generated, the quality of the product is reduced, which actually becomes a big problem. This phenomenon is greatly influenced by the mixing ratio of the olefin polymer having carboxyl groups. In the method of the present invention, as mentioned above,
Since the mixing ratio of the olefin polymer can be reduced, gelation problems hardly occur, and stable continuous production over a long period of time is possible. Thus, the present invention has the advantage that the manufacturing process can be carried out very easily. Next, the present invention will be explained in more detail with reference to Examples. Example 1 Nylon 66 having a formic acid relative viscosity (JIS-K-6810) of 52, a terminal amino group content of 53 milligram equivalents/Kg, and a terminal carboxyl group content of 55 milligram equivalents/Kg.
It is composed of 94.4 mol% ethylene and 5.6 mol% methacrylic acid, with some of the carboxyl groups converted to zinc salt (conversion 15.3 mol%), melt index (ASTM-D-1238, 190°C, 2.16 kg). )
A modified polyamide resin was produced using an ethylene ionomer having a yield of 1.9 g/10 minutes. In other words, nylon 66 particles (3 mm × 3 mm
^L ) 176Kg and ethylene ionomer particles (3mm
〓×3mm ^L )24Kg and 70mm〓(L/
After melt-mixing at a temperature of 280° C. using a screw extruder (D=30), the mixture was granulated into particles of 3 mm × 3 mm ^L (mixed composition 1-A). Next, 50 kg of particles of this mixed composition 1-A were placed in a rotary dryer (capacity:
100℃ for 7 hours at 190℃ and 240℃ of dry nitrogen.
Heated while flowing at a rate of / hour. For the product thus obtained (modified resin 1), Izot impact strength (ASTM-D-256)
and tensile yield strength (ASTM-D-638) were measured. Further, the above mixed composition 1-A was also measured in the same manner. On the other hand, Izot impact strength and tensile yield strength were measured for Mixed Composition 1-B obtained by melt-mixing 40 kg of the above nylon 66 and 10 kg of the above ethylene ionomer in the same manner. The above measurement results are shown in Table 1.

[Table] Example 2 Nylon 66 with formic acid relative viscosity (JIS-K-6810) 46, terminal amino group content 96 milligram equivalents/Kg, terminal carboxyl group content 36 milligram equivalents/Kg
It consists of 92.1 mol% of ethylene and 7.9 mol% of methacrylic acid, with some of the carboxyl groups converted to zinc salt (degree of conversion 44 mol%), melt index (ASTM-D-1238, 190℃, 2.16Kg )0.6
A modified polyamide resin was produced using an ethylene ionomer having a viscosity of 1.5 g/10 min. In other words, nylon 66 particles (3 mm × 3 mm
^L ) 176Kg and ethylene ionomer particles (3mm
〓×3mm ^L )24Kg and 70mm〓(L/
After melt-mixing at a temperature of 280° C. using a screw extruder (D=30), the mixture was granulated into particles of 3 mm × 3 mm ^L (mixed composition 2). Next, 50 kg of particles of this mixed composition 2 were placed in a rotary dryer (capacity 100) at 150°C for 5 hours.
Heated for 10 hours with dry nitrogen flowing at a rate of 240/hour. The products thus obtained (modified resins 2-A and 2-B) were measured for Izod impact strength (ASTM-D-256) and tensile yield strength (ASTM-D-638). Further, the above mixed composition 2 was also measured in the same manner. The above measurement results are shown in Table 2.

[Table] Example 3 Nylon 6 having a sulfuric acid relative viscosity (JIS-K-6810) of 2.4, a terminal amino group content of 50 milligram equivalents/Kg, and a terminal carboxyl group content of 70 milligram equivalents/Kg.
and a copolymer consisting of 82% by weight of ethylene and 18% by weight of vinyl acetate, with 8 parts by weight of acrylic acid per 100 parts by weight.
Melt index (ASTM-D-1238, 190℃, 2.16Kg) 2.5g/
Modified polyamide resin was manufactured using EVA graft polymer with 10 minutes. That is, particles of nylon 6 (3 mm × 3 mm
^L ) 176Kg and EVA graft polymer particles (3mm〓
×3mm ^L )24Kg and 70mm〓(L/D
= 30) screw type extruder at a temperature of 260°C, and then granulated into particles of 3 mm × 3 mm ^L (mixed composition 3). 50 kg of particles of this mixed composition 3 were then heated in a rotary dryer (capacity 100) at 190° C. for 7 hours while flowing dry nitrogen at a rate of 240°/hour. The product thus obtained (Modified Resin 3) has Izod impact strength (ASTM-D-256) and tensile yield strength (ASTM
-D-638) was measured. Further, the above mixed composition 3 was also measured in the same manner. The above measurement results are shown in Table 3.

【table】

Claims (1)

[Scope of Claims] 1. After melt-mixing 60 to 95% by weight of polyamide and 40 to 5% by weight of olefinic polymer having carboxyl groups and granulating the resulting granules, the resulting granules are subjected to vacuum or inert gas flow. Below, a method for producing a modified polyamide resin, which is characterized by carrying out condensation through a heating reaction at a temperature below the melting point of the polyamide. 2. The method according to claim 1, wherein the granules are heated and reacted at a temperature of 120 to 220°C for at least 30 minutes. 3. 20 parts by weight of a reinforcing inorganic filler for 100 parts by weight of a mixture consisting of 60-95% by weight of polyamide and 40-5% by weight of an olefinic polymer having carboxyl groups.
~200 parts by weight are blended, melt-mixed and granulated, and the resulting granules are subjected to a heating reaction under vacuum or inert gas flow at a temperature below the melting point of polyamide to perform condensation. A method for producing a reinforced modified polyamide resin characterized by: 4. The method according to claim 3, wherein the granules are heated and reacted at a temperature of 120 to 220°C for at least 30 minutes.