JPH04288364A - Polyamide composition - Google Patents

Abstract

PURPOSE:To obtain a polyamide composition improved in injection molability by depositing a specified copolymer and then a higher fatty acid salt of a group I-III metal of the periodic table on the surface of a polyamide chip. CONSTITUTION:The title composition is obtained by depositing 0.01-0.5wt.% normally liquid propylene oxide/ethylene oxide block or random copolymer having an absolute viscosity (at 30 deg.C) of 10-1000cP and an ethylene oxide content of 20-60wt.% on the surface of a polyamide chip (e.g. nylon 6 chip) in the form of a cylinder of a diameter of 1.5-3.0mm and a height of 1.5-3.0mm or a plate of a depth of 1.5-3.0mm, a width of 1.5-3.0mm and a height of 1.5-3.0mm and further depositing thereon 0.01-0.5wt.% higher fatty acid salt of a group I-III metal of the periodic table (e.g. magnesium stearate).

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to new polyamide compositions, and more particularly to polyamide compositions with improved injection moldability.

0002

BACKGROUND OF THE INVENTION In recent years, there has been a growing trend toward continuous or unmanned operation of injection molding. Therefore, as well as improving the performance of injection molding machines, polyamide chips with improved moldability are required. In other words, it is stably supplied to the injection molding machine, is easy to release from the mold, does not form a bridge at the chip inlet of the molding machine's hopper, and has a shorter plasticization time and less variation. There is a demand for polyamide compositions with excellent moldability. Such polyamide compositions can be improved to some extent by increasing the molding temperature, but this has an adverse effect on the quality of the molded article.

Furthermore, in order to improve the injection moldability of polyamide, it has been proposed to use higher fatty acids or their metal salts as surface lubricants and internal lubricants for polyamide chips. However, conventionally used lubricants are powder-like solids under normal conditions (handling temperature), and there is a limit to the amount that can be stably attached to the surface of polyamide chips, and there is a limit to the amount that can be stably attached to the surface of polyamide chips. It is also difficult to improve the injection moldability of polyamide to a satisfactory level.

0004

[Problems to be Solved by the Invention] Therefore, the present invention provides a plasticizer that can be stably supplied to an injection molding machine, has a uniform and short plasticizing time even at low molding temperatures, and is free from warping, distortion, etc. during mold release. The objective of this project was to develop a polyamide composition that has excellent moldability and is suitable for injection molding.

[0005]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present inventors have conducted intensive research and study, and as a result, have finally completed the present invention. That is, the present invention involves attaching a block or random copolymer of propylene oxide and ethylene oxide, which is normally liquid, to the surface of a polyamide chip in an amount of 0.01 to 0.5 wt% with respect to the chip. After that, a higher fatty acid salt of a metal belonging to Groups I to III of the periodic table was attached to the chip in an amount of 0.01 to 0.5 wt%, resulting in extremely excellent injection moldability. The present invention provides a polyamide composition having the following properties.

The polyamides used in the present invention include nylon 6, nylon 6,6, nylon 11, and nylon 1.
2, nylon 6,10, nylon 6,12, etc., but are not limited to these. It is used in the form of a chip, and its shape and size are not particularly limited, but it is usually cylindrical with a diameter and height of 1.5 mm to 3.0 mm, or a cylindrical shape with a length, width, and height. It is preferable to use a plate-shaped chip with a diameter of 1.5 mm to 3.0 mm.

[0007] A block or random copolymer of propylene oxide and ethylene oxide that is normally liquid and used in the present invention (hereinafter referred to as block or random copolymer)
is represented by the following general formula (I), and can be used as a type of polymeric nonionic surfactant in which the polypropylene oxide group at the center is a hydrophobic group and the polyethylene oxide groups at both ends are hydrophilic groups. In the invention, the absolute viscosity (30°C) is 1
It is preferable that the ethylene oxide has a range of 0 centipoise to 1000 centipoise and the weight percent of ethylene oxide in the whole molecule is about 20 to 60. HO-(C2H4O)n-(C3H6O
)m -(C2H4O)n -H (I) These block or random copolymers have good dispersibility, heat resistance, and external lubricity, so they can be uniformly attached to the polyamide chip surface with a small amount of use, and It also has an excellent ability to retain higher fatty acid metal salts that are subsequently attached.

Further, the higher fatty acid metal salt is a salt of a higher fatty acid having 9 to 25 carbon atoms, such as lauric acid, palmitic acid, or stearic acid, and a metal belonging to groups I to III of the periodic table, and is an effective and preferred metal salt. is calcium, magnesium,
These include zinc and aluminum.

In the present invention, the block or random copolymer and higher fatty acid metal salt are used in an amount of 0.01 to 0.5 wt % based on the polyamide chip. If the amount used is less than the lower limit above,
It becomes difficult to obtain the effects of the present invention, and if the amount exceeds the above upper limit, molding problems such as poor penetration of the composition may occur when using a screw type molding machine.
Furthermore, there is a possibility that the quality of the molded product will be adversely affected.

[0010] There are no particular restrictions on the method of attaching the block or random copolymer and higher fatty acid metal salt to the polyamide chips. A method can be adopted in which a block or random copolymer is attached to the surface, the chip surface is moistened, and then a higher fatty acid metal salt is attached.

The polyamide composition of the present invention is particularly suitable for injection molding, but can also be applied to other known molding methods such as extrusion molding and compression molding. The polyamide composition of the present invention may also contain appropriate amounts of known lubricants, antistatic agents, flame retardants, colorants, crystal nucleating agents, fillers, reinforcing agents, heat resistant agents, weather resistant agents, and the like.

0012

EXAMPLES Next, the present invention will be specifically explained using Examples and Comparative Examples, but the present invention is not limited thereto. The physical properties in each example were determined as follows.

Physical Property Tests Tests were conducted on the polyamide compositions in each example to determine the plasticization time, length of spiral flow, and mold release force using an injection molding machine under the molding conditions shown below. (1) Molding conditions for determining plasticization time Cylinder temperature: 220-235-250-250 (℃), (hopper side) (nozzle side) Injection-cooling-intermediate time: 2-60-0 (seconds), back pressure :6
0 (kg/cm2) Measurement: Actual measurement 65 (mm)/Full stroke measurement 130 (
mm) Screw rotation speed: 66 (rpm) Number of shots: 50 shots (2) Molding conditions for determining the length of spiral flow Resin temperature: 250 (℃), Mold temperature: 80 (℃), Injection (
1st) Pressure: 1200 (kg/cm2) Injection - Cooling -
Intermediate time: 5-5-10 (seconds), measurement: actual measurement 40 (m
m)/Full stroke measurement 130 (mm) Screw rotation speed: 143 (rpm) Spiral cross-sectional dimensions: (trapezoid) 3 x 3 x 5 (mm) (3
) Conditions for determining mold release force Resin temperature: 250 (℃), Mold temperature: 30 (℃) Injection pressure: (Primary pressure) 360 (kg/cm2) - (Secondary pressure) 480 (kg/cm2) Injection - Cooling - Intermediate time (seconds): 20-30-10 (seconds)
Measurement: Actual measurement 45 (mm) / Full stroke measurement 130 (
mm) Mold required for evaluation: (box type) 75 x 100 x 30 (mm)
) Thickness: 3 (mm) The force applied to the ejector pin during mold release was measured.

Examples 1 to 4, Comparative Example 1 100 parts by weight of polyamide chips (nylon 6) were added with Newpol PE manufactured by Sanyo Chemical Co., Ltd. as a block copolymer.
-62 in the amounts shown in "Table 1" using a V-type blender, and then magnesium stearate in the amounts shown in "Table 1" were added and mixed to obtain a polyamide composition. The results are also listed in "Table 1". Comparative Examples 2 and 3 In place of the block copolymer in Example 4, Comparative Example 2
So, polyoxyethylene sorbitan fatty acid ester is 0
．． A polyamide composition was obtained in the same manner as in Example 4, except that 0.03 parts by weight of castor oil was used in Comparative Example 3. The results are also listed in "Table 1". Comparative Example 4 A polyamide composition was obtained in the same manner as in Example 1, except that magnesium stearate was not used. The results are also listed in "Table 1". Comparative Example 5 0.03 parts by weight of the same block copolymer as in Example 1 was applied to 100 parts by weight of polyamide chips (nylon 6) using a V-type blender, and then 0.03 parts by weight of magnesium stearate was added.
2 parts by weight were added and mixed, extruded using a screw extruder, and pelletized to obtain a polyamide composition. The results are also listed in "Table 1". Comparative Example 6 0.03 parts by weight of oleyl alcohol was applied to 100 parts by weight of polyamide chips (nylon 6) using a V-type blender, and then 0.2 parts by weight of magnesium stearate was added and mixed to obtain a polyamide composition. The results are also listed in "Table 1".

[0015]

[Table 1]

[0016]

Effects of the Invention As is clear from Table 1 above, the polyamide composition of the present invention has, for example, a polyamide composition in which a solid lubricant such as a higher fatty acid metal salt is blended. The ability to penetrate into the screw of the injection molding machine has been greatly improved, the plasticization time and its dispersion have also been greatly reduced, and the mold releasability from the mold is also good, so injection molding can be performed very efficiently. It is a great contribution to industry.

Claims (1)

[Claims] 1. A block or random copolymer of propylene oxide and ethylene oxide, which is normally liquid, is applied to the surface of a polyamide chip at a rate of 0.01%.
After adhering in a range of ~0.5 wt%, higher fatty acid salts of metals belonging to Groups I to III of the periodic table were further deposited on the chip in a range of 0.01 to 0.5 wt%. A polyamide composition characterized by: