JPH09118822A - Polyamide composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having lubricating properties by blending a poly-ε-caprolactam with a polyethylene wax and a modified polyethylene wax to uniformly disperse the blend. SOLUTION: This polyamide composition is obtained by blending (A) 100 pts.wt. of a poly-ε-caprolactam with (B) 1-12 pts.wt. of a polyethylene wax and (C) 0.1-5 pts.wt. of a modified polyethylene wax containing a hydroxyl group or an epoxide group at the end and/or side chain. For example, preferably the component B and the component C are added to (D) anhydrous ε- caprolactam and heated in the presence of an anionic polymerization derivative and a polymerization cocatalyst at a temperature equal to or higher than the melting point of the component D and equal to or lower than the melting point of the component A (generally 130-180 deg.C) to subject the component D to anionic polymerization.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyamide composition, and more particularly to a monomer-cast nylon composition having a lubricity obtained by uniformly dispersing and blending a wax in a polyamide resin.

[0002]

2. Description of the Related Art Polyamides, especially monomer-cast nylons, have a sliding property and are used as a sliding material in a lubricant-free state, but under the conditions of high speed, high load, etc., the polyamide itself has a lubricating property. Since it is not enough, it is proposed to add a lubricant. Wax or the like is used as the lubricant.

[0003]

When wax is used as a lubricant, ε-caprolactam is anionically polymerized,
When the polyamide resin is obtained, the molten ε-caprolactam and the lubricant may be separated due to the difference in specific gravity and the non-melting property, and the lubricant may be dispersed unevenly. When the dispersion of the lubricant becomes non-uniform, the degree of lubricity becomes partially non-uniform within the product itself, or a site having a different appearance is generated. Further, the degree of lubricity may vary among products of the same type, or products with different appearances may occur. Further, since the lubricant is easily separated, the molding conditions are restricted.

[0004]

[Means for Solving the Problems] The inventors of the present invention have made extensive studies to solve the above-mentioned problems of the prior art and to obtain a polyamide composition obtained by uniformly dispersing and blending a lubricant, and achieved this object. The present invention has been reached. That is, the gist of the present invention is that 100 parts by weight of poly-ε-caprolactam, 1 to 12 parts by weight of polyethylene wax and 0.1 to 5 parts of modified polyethylene wax having a hydroxyl group or an epoxide group at the terminal and / or side chains. It exists in a polyamide composition obtained by dispersing and blending in a proportion of parts by weight.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The polyethylene wax used in the present invention (hereinafter abbreviated as PE wax) has a relatively low molecular weight such as a molecular weight of 800 to 12000, and its melting point is usually 90 to 140 ° C. For example, it is obtained as a by-product when ethylene is polymerized to produce polyethylene, or by decomposition of ethylene or direct polymerization.

The modified polyethylene wax having a hydroxyl group or an epoxide group at the terminal and / or side chain used in the present invention (hereinafter, the modified polyethylene wax may be abbreviated as modified PE wax) has a molecular weight of about 800 to 12000 and a melting point. Is usually 90 to 140 ° C. The modified PE wax having these polar groups may be produced according to a method conventionally known as a polar group introduction / addition method. For example, to add a hydroxyl group, the end of PE wax is once replaced with ethylene oxide, and then it is further converted into a hydroxyl group. The addition of the epoxide group is
For example by treatment with peracetic acid. The PE wax obtained by these methods has about 1 to 3 hydroxyl groups or epoxide groups at the terminal or side chain.

In the present invention, the blending ratio of PE wax is 1 to 1 with respect to 100 parts by weight of poly-ε-caprolactam.
It is 2 parts by weight, preferably 2 to 6 parts by weight. This ratio is 1
If it is less than 10 parts by weight, the lubricating effect is poor, while if it exceeds 12 parts by weight, the mechanical strength of the composition decreases, which is not preferable as an engineering plastic. In the present invention, the proportion of the modified PE wax having a hydroxyl group or an epoxide group at the terminal and / or side chain is 0.1 to 5 parts by weight, preferably 100 parts by weight of poly-ε-caprolactam.
0.3 to 3 parts by weight. If this proportion is less than 0.1 parts by weight, the effect of dispersing the lubricant will be poor, while if it exceeds 5 parts by weight, the polymerization of ε-caprolactam will be impaired, and the mechanical strength of the composition will decrease.

The modified PE wax to be blended in the present invention has a hydroxyl group at the terminal and / or side chain, and also at the terminal and / or
Alternatively, those having an epoxide group in the side chain may be blended alone or in combination of both, or in addition to these blends, a modified PE wax having another polar group such as a carboxyl group may be added. The modified PE wax may be one having a polar group such as a hydroxyl group or an epoxide group at one end (or side chain), and may have another polar group at the other end (or side chain).

The composition of the present invention can be produced by a conventionally known anionic polymerization method. That is, anhydrous ε-caprolactam was added to PE wax and the above-mentioned modified P.
E wax is added and heated to a temperature not lower than the melting point of ε-caprolactam and not higher than the melting point of poly ε-caprolactam (usually 130 to 180 ° C.) in the presence of an anionic polymerization catalyst and a polymerization promoter to anionicly polymerize ε-caprolactam. The polymerization catalyst and the polymerization co-catalyst may be those usually used, and examples of the polymerization catalyst include alkali metals, alkaline earth metals or hydrides of these metals, hydroxides, oxides, and the like. For example, isocyanates, triazines and substituted ureas are usually used within the range of 0.05 to 2 mol%.

[0010]

EXAMPLES Examples of the present invention and comparative examples for comparison will be shown below, but the present invention is not limited to the following examples. In the following examples and comparative examples, for each composition, the limit PV value (unit is kg / cm ² · m
/ Min) and tensile strength (kg / cm ² ) were measured. The limit PV value indicates the evaluation of lubricity and wear resistance, and this value is a surface pressure (P) of a polyamide molded product and S-45C steel by a Suzuki type wear and friction tester manufactured by Toyo Ballwind Co., Ltd. 50
The maximum value of PV that does not cause abnormal wear for 3 minutes is shown, which is weighted for each (kg / cm ² ), and rubbed at a friction speed (V) of 5 (m / min). The shape and size of the mold for molding the composition is the inner diameter
A 50 mm, 1200 mm long steel tube with a bottom lid, installed vertically. The tensile strength is a value obtained by performing the ASTM standard D-638 method at room temperature.

Examples 1 to 11 and Comparative Examples 1 to 6 Stainless steel beaker with anhydrous ε-caprolactam 50
Take part by weight and adjust to 160 ° C. To this, 0.5 part by weight of tolylene diisocyanate as a polymerization co-catalyst was added, and further pre-melted PE wax (molecular weight 4000, melting point 132
1 to 3 at the end of one side of PE wax or at the side chain.
The modified wax having individual hydroxyl groups or epoxide groups introduced is added at a ratio of various parts by weight shown in Table 1 below and stirred uniformly. Anhydrous ε-in another stainless steel beaker
Take 50 parts by weight of caprolactam, and add 0.2 parts by weight of sodium hydride (63% oily) as a polymerization catalyst to 150 ℃. This was mixed with a mixture containing the above PE wax and the like to homogenize the system, and then the mixture was poured into a mold at 160 ° C. to obtain a cylindrical molded article of a poly ε-caprolactam composition in which a lubricant and the like were dispersed. Obtained.

In the obtained poly ε-caprolactam composition, the amount of PE wax (part by weight) blended in the production of the poly (ε-caprolactam) and the modified PE wax are divided into those having a hydroxyl group and those having an epoxide group. ,
Each compounding amount (part by weight) and the upper part (50 mm from the upper part of the molded product) and the lower part of the molded product of the obtained composition
Table 1 shows the limiting PV value (unit: kg / cm ² · m / min) and tensile strength (unit: kg / cm ² ) of (30 mm from the bottom of the molded product). In the table, Ex 1 indicates Example 1 and Ratio 1 indicates Comparative Example 1, which will be referred to hereinafter.

[0013]

[Table 1]

Examples 12 to 14 and Comparative Examples 7 to 12 100 parts by weight of ε-caprolactam preliminarily adjusted to 160 ° C. was taken in a glass graduated cylinder having a capacity of 100 CC.
PE wax (molecular weight 4000, melting point 132 ° C.) previously adjusted to 160 ° C. and modified PE wax in which 1 to 3 hydroxyl groups or epoxide groups were introduced into one end and / or side chain of the PE wax were added. The mixture was added at various parts by weight shown in Table 2 below, sealed, and shaken for 20 seconds to mix thoroughly, and then heated in an oven at 160 ° C for 10 seconds.
Immediately after standing for a minute, the separated PE wax and modified P
Table 2 shows the separated amount (parts by weight) of the mixture of both E waxes (referred to as total PE wax in Table 2 below).

[0015]

[Table 2]

The examples in Table 2 above all compare the total amount of PE wax collected during the production of the composition of the present invention. The separation amount of the PE wax is 0, whereas the separation amount of the total PE wax is large at the ratios outside the present invention. According to such a mixing ratio, the physical properties of the obtained composition are not uniform, which is not preferable. It can be called obvious. It should be noted that Comparative Example 12 is a reference example showing that no separation occurs even if a large amount of modified PE wax is blended. In addition, in Table 2, Ex. 12 is Example 12 and ratio 7
Represents Comparative Example 7, and is similarly displayed below.

An example of the embodiment of the present invention is as follows. (1) A polymer produced by a monomer casting method, wherein 100 parts by weight of poly-ε-caprolactam and P
1 to 12 parts by weight of E wax and 0. modified PE wax having a hydroxyl group or an epoxide group at the terminal and / or side chain.
A polyamide composition prepared by dispersing and blending at a ratio of 1 to 5 parts by weight. (2) A polyamide composition in which the PE wax to be blended has a molecular weight of 800 to 12000. (3) A polyamide composition in which the PE wax to be blended has a melting point of 90 to 140 ° C. (4) The modified PE wax to be blended has a molecular weight of 800 to 12000.
A polyamide composition. (5) A polyamide composition in which the modified PE wax to be blended has a melting point of 90 to 140 ° C.

[0018]

According to the present invention, it is difficult to disperse P by itself.
By blending E wax with a modified PE wax having a hydroxyl group or an epoxide group at the terminal and / or side chain, a polyamide composition in which the above blend is uniformly dispersed can be obtained.

Claims (1)

[Claims] 1. A ratio of 1 to 12 parts by weight of polyethylene wax and 0.1 to 5 parts by weight of modified polyethylene wax having a hydroxyl group or an epoxide group at the terminal and / or side chain per 100 parts by weight of poly-ε-caprolactam. A polyamide composition prepared by dispersing and blending with.