JP2000127180A - Manufacture of polyamide resin molding with core material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a molding with little sinkage without insufficient polymerization by setting a core material in a mold, casting a polymerizable lactam liquid obtained by adding an anionic polymerization catalyst and an initiator to an anhydrous lactam in the mold, inserting a pressurizing piston into an opening, pressurizing, heating and polymerizing, and releasing the molding from the mold after completion. SOLUTION: A lengthy core material 2 is set at a center in a cavity 14 of a molding machine 10 in a thickness direction. A jacket 12 is preheated and regulated to a predetermined temperature, and a polymerizable lactam liquid 17 obtained by adding an anionic polymerization catalyst and an anionic polymerization initiator to an anhydrous lactam is substantially cast from an upper opening in the mold. A pressurizing piston 12 is inserted from the opening into the cavity 14 to pressurize the liquid 17 to complete its polymerization. Further the piston 13 is raised after cooling, only the jacket 12 is raised in the state that its bottom 11 is fixed. Then a mold released preform is cut in a predetermined size, thereby obtaining the molding. Thus, the molding having small sinkage or inner defect can be efficiently manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyamide resin molded article having a core material embedded therein, and more particularly to a core material for gears, rollers, wheels, etc. used under relatively high loads and high temperatures. The present invention relates to a method for producing a polyamide resin molded article in which demolding of a polyamide resin molded article having embedded therein is performed in a short time, and in which insufficient polymerization and sink marks are reduced.

[0002]

2. Description of the Related Art Polyamide molded articles are often used as substitutes for metal gears, rollers, wheels, etc. for the purpose of weight reduction, oil-free operation, noise reduction, and the like. However, when used under extremely high load conditions or when used under normal conditions for a long period of time, the limit may be exceeded, and breakage may occur from the key groove existing at the boundary between the polyamide resin portion and the shaft.

For this reason, a structure has been proposed in which only the boss portion is made of metal while taking advantage of the features that the polyamide resin is lightweight and maintenance-free and can be used for a long period of time. As a method of fixing the metal boss portion to the polyamide resin portion, a method of cold press-fitting, a method of press-fitting the heated and expanded polyamide resin portion into the metal boss portion (shrink fitting method), a method of mechanically fixing with a screw, etc. Was commonly done. Japanese Patent No. 2622813 discloses a method in which a polyamide resin portion is cold-pressed into knurled metal, and the metal is heated to fuse and integrate the polyamide resin portion and the metal.

[0004]

However, each of these methods has its own problems. First, in the cold press-fitting method and the shrink-fitting method, the fixing force between the metal boss portion and the polyamide resin portion is sometimes short in a short time.

Further, the holding force of the polyamide resin portion is reduced by thermal expansion of the polyamide resin at a high temperature and relaxation of stress due to long use, and the fixing force is further reduced. Concentration makes the polyamide resin part easily broken. In some cases, screws cannot be attached depending on the product shape.
To avoid this, if the press-fitting margin and shrink-fitting margin at the time of manufacture are set to be large, excessive distortion will occur on the resin side, and when processing to a predetermined size or when using as a part, the distortion will cause Sometimes it was destroyed.

Further, the method of cold-pressing a polyamide resin portion into a metal, heating the metal, and fusing and integrating the both has a problem that the number of processing steps is large and the product is expensive.

For this reason, as a low-cost method, a metal reinforcing material subjected to knurling is placed in a mold and then molded by pouring a polymerizable lactam liquid, but this occurs during the polymerization process. A gap is generated between the polymer and the metal reinforcing material due to shrinkage due to the shrinkage, and a sink occurs to cause a problem that a good product cannot be obtained.

Further, when the molded article is removed from the mold after the polymerization is completed, the mold is turned upside down. However, the molded article may be held on the support base, and it takes time to remove the molded article. I was

The present invention solves these problems, and makes use of the advantages of polyamide resin, is lightweight, can be used for a long time without lubrication, facilitates demolding of the polyamide resin molded article, and insufficient polymerization. It is an object of the present invention to provide a method for producing a polyamide resin molded article in which the occurrence of shrinkage and sink marks is reduced and the bonding strength between the polyamide resin and the reinforcing material is maintained.

[0010]

In order to achieve the above object, the present invention provides a method for manufacturing a core-containing polyamide resin molded article in which a core material is embedded in a molded article. A polymerizable lactam liquid obtained by adding at least an anionic polymerization catalyst and an anionic polymerization initiator to a substantially anhydrous lactam using a polymerization apparatus comprising a pressure piston inserted into the opening and a core material set in a mold. Is injected into a mold, a pressurizing piston is inserted into the opening, and pressurized and heated to polymerize, and after the polymerization is completed, the mold is released.

As described above, by fixing the core material in the mold and performing pressure polymerization, it is possible to efficiently produce a molded article having few sink marks and internal defects.

[0012] Claim 2 includes a step of cutting to a predetermined size after the mold is released. A long molded body is formed by pressure polymerization, and then cut to a required size. Efficiency can be increased and costs can be reduced.

According to a third aspect of the present invention, the mold is divided into a bottom portion and a jacket portion, and the jacket portion can be moved up and down, and after the polymerization is completed, the jacket portion is lifted to release the mold.

By dividing the bottom of the mold and the jacket so that the jacket can be moved up and down, the molded product can be easily removed from the mold and the production efficiency can be increased.

Next, in a fourth aspect, the core material is set using a core material guide which is fixed to the core material and abuts on the mold.

By setting the core material in the mold using a guide, the exact position of the core material in the polyamide can be ensured.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a plan view of a polyamide resin molded article obtained by the production method of the present invention, FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG. It is a perspective view of the core used.

The polyamide resin molded article 1 produced by the method of the present invention is, for example, a disk as shown in FIGS. 1 and 2, and has a through hole 3 in the center and a side face 4 as shown in FIG. One groove-shaped portion 5 is provided along the circumferential direction, and at the outer peripheral portion of the metal core material 2 having a notch 6 for preventing rotation at predetermined intervals along the circumferential direction and along the thickness direction. The teeth (not shown) are formed by later machining,
Used as a gear for high loads. At the time of subsequent processing, the through-hole 3 is attached to the grip portion of the lathe.

In addition, as the core material 2, a through hole 3 is formed in the center portion as shown in FIG.
And a shape having a notched groove 6 for preventing rotation at a predetermined interval along the circumferential direction and along the thickness direction.

The one groove portion 5 and the convex portion 7 prevent the residual shrinkage stress generated during the polymerization of the polyamide resin and uniformly shrink, thereby satisfactorily holding the core material 2 and mechanically. Is also locked, so that the polyamide resin 9 is
Does not escape easily from The notch 6 prevents the polyamide resin 9 from rotating from the core 2.

FIG. 5 is a cross-sectional view of a core material placed in a mold and cast in the manufacturing method of the present invention, FIG. 6 is a cross-sectional view of polymerization under pressure in the manufacturing method of the present invention, and FIG. 7 shows a cross-sectional view of a state where the molded body is removed from the mold.

As shown in FIG. 5, a molding apparatus 10 used for producing the above-mentioned polyamide resin molded article 1 has a cylindrical jacket portion 12 made of aluminum, iron or the like, having a high thermal conductivity and a cylindrical shape. The mold M includes a cylindrical bottom 11 having an outer diameter substantially the same as the inner diameter, and a pressurizing piston 13 also having an outer diameter substantially equal to the inner diameter of the jacket 12. 12 having a cavity 14 formed therein.
The jacket portion 12 is attached to be vertically movable independently of the bottom portion 11.

Further, the jacket portion 1 is opened from the upper opening.
The pressurizing piston 13 having the same outer diameter as the inner diameter of the piston 2 is inserted. The pressurizing piston 13 is connected to a pressurizing means such as a hydraulic cylinder, so that the inside of the cavity 14 can be pressurized. ing. A packing 15 is mounted around the bottom 11 and the pressure piston 13 so that the polymerizable lactam liquid does not leak.

The size of the cavity 14 of the molding apparatus 10 in the thickness direction of the molded body 1 is longer than the thickness of the molded body 1, and the intermediate molded body 16 obtained by polymerization is cut. A plurality of compacts 1 at once
You can get.

The polymerization method of the polyamide resin molded article of the present invention using the molding apparatus 10 will be described. Here, a procedure for molding a cylindrical molded body having a predetermined thickness used for gears will be described as an example.

First, a long core material 2 is set at the center of the cavity 14 of the molding apparatus 10 in the thickness direction. After preheating the jacket portion 12 and adjusting the temperature to 100 to 180 ° C, a polymerizable lactam liquid 17 obtained by adding at least an anionic polymerization catalyst and an anionic polymerization initiator to a substantially anhydrous lactam is cast from the upper opening ( (Fig. 5).

Here, the ω-lactam is dehydrated under reduced pressure in a dehydration tank to make it substantially anhydrous, and then replaced with an inert gas such as nitrogen. Ω- in the dehydration tank
The lactam is weighed into two casting tanks,
Thereafter, a predetermined amount of an anionic polymerization catalyst is charged into one casting tank containing ω-lactam, and a predetermined amount of anionic polymerization initiator is charged into the other casting tank containing ω-lactam. You may.

Subsequently, the pressure piston 13 is moved through the upper opening.
Is lowered and inserted into the cavity 14, and the lactam liquid 17
After reaching the surface of the lactam liquid 17
Is pressurized. The pressurization at this time is preferably performed at 2 MPa or more (FIG. 6).

After 80 to 160 minutes have passed under the pressurized condition, the polymerization is completed. After further cooling, the pressurizing piston 13 is raised and only the jacket portion 12 is raised with the bottom portion 11 fixed, thereby completing the polymerization. Intermediate molded body 16
Is released (FIG. 7).

After the mold is removed, the intermediate molded body 16 is cut into a predetermined size, whereby the molded body 1 for gears can be obtained. To actually make a gear, the polyamide resin portion around the core 2 is processed into a gear shape.

The pressurization of the polymerized lactam liquid by the pressurizing piston 13 is less than 2 MPa, which is not preferable because the pressurization is insufficient and shrinkage such as sink marks is liable to occur in the molded product.

The core material 2 is set in the cavity 14. A rod-shaped core material guide 18 is mounted near the upper end and lower end of the long core material 2 at right angles to the core material 2, and the inner wall of the jacket portion 12 is formed. Also, the concentricity of the core material 2 with respect to the polyamide resin can be ensured. The core material guide 18 is not limited to this form.
A method may be adopted in which the recess provided in 1 is used as a core guide, and the core is fixed by mounting the core in the recess. It is also possible to use both the method of mounting in the concave portion and the method of using a rod-shaped core material guide.

The lactam used in the present invention may be substantially anhydrous α-piperidone, ε-caprolactam, ω-laurolactam, ω-enantholactam, caprylactam, ω-decanolactam, ω-undecanolactam, or a mixture thereof. Industrially advantageous lactams, which are mixtures of two or more, are ε-caprolactam and ω-laurolactam.

The anionic polymerization catalyst used in the present invention includes sodium hydride, lithium hydride, sodium,
A known lactam polymerization catalyst such as potassium can be used, and its addition amount is 0.1 to 2.0 mol% based on the lactam.

The anionic polymerization initiator is, for example, N-acetyl-ε-caprolactam, isocyanate, diisocyanate, urea derivative, urethane, isocyanurate derivative, the amount of which is 0.05 to 1. A range of 0 mol% is preferred.

In the above-mentioned production method, a method in which an anionic polymerization catalyst is added to and dissolved in a lactam, and then an anionic polymerization initiator is added or mixed during or after casting, or a lactam containing an anionic polymerization catalyst and an anionic polymerization initiator are mixed. It is adjusted by a method of adding and mixing the lactam to be contained during or after the casting.

The lactam is polymerized at 100 to 210 ° C.
Temperature, but preferably from 130 to 18
0 ° C.

In carrying out the method of the present invention, it is also possible to add, besides the above components, oils which do not inhibit polymerization, waxes, swelling agents such as calcium stearate, and reinforcing materials such as carbon fibers and glass fibers. is there.

Hereinafter, a manufacturing apparatus which can be used in the present invention and a process using the same will be described in detail.

After dehydration, ε-caprolactam in the dehydration tank was weighed and placed in two casting tanks, 1.250 g in one casting tank and 1.250 g in the other casting tank.
After adding 250 g, 4.0 g of sodium hydride (63% oil) was added and dissolved in one casting tank, and 5.6 g of triphenylisocyanurate was added to the other casting tank. During this time, the polymerizable lactam liquid was mixed while the temperature was raised to 125 ° C. while flowing nitrogen in the casting tank under atmospheric pressure.

A manufacturing apparatus as shown in FIG. 5 has an inner diameter of 80 to 95 mm and a height of 1000 to 13 mm.
The outer diameter of the packing is 80-95 mm, the outer diameter of the packing is 80-95 mm, and the inner wall of the jacket is hollow so that heated oil can pass through. The temperature can be controlled by

Subsequently, a core material having a length of 900 mm and a rod-shaped core material guide mounted near the upper and lower ends in a direction perpendicular to the core material was formed by the bottom portion and the jacket portion such that the core material guide fits into a fixed portion inside the jacket. It is set in the cavity, and the polymerizable lactam liquid mixed from the upper opening of the cavity is cast to about 100 to 150 mm above the upper end of the core material.

Next, the pressurizing piston was lowered and inserted into the cavity, pressurized, and kept in that state for 80 to 160 minutes until the completion of polymerization. By raising the jacket together with the pressurizing piston, the intermediate molded body inside was released from the mold and cut to a predetermined thickness, thereby obtaining 40 molded bodies serving as gears.

[0044]

According to the first aspect of the present invention, there is provided a method for producing a core-containing polyamide resin molded article in which a core material is embedded in a molded article. Using a polymerization apparatus consisting of a pressure piston inserted, with the core material set in the mold, mold a polymerizable lactam liquid obtained by adding at least an anionic polymerization catalyst and an anionic polymerization initiator to substantially anhydrous ω-lactam. It is characterized in that it is poured into the inside, the pressurizing piston is inserted into the opening, and pressurized and heated to polymerize, and after the polymerization is completed, it is released from the mold.

By fixing the core material in the mold and performing pressure polymerization in this manner, a molded article with less sink marks and internal defects can be efficiently produced.

Claim 2 includes a step of cutting to a predetermined size after demolding. A long molded body is formed by pressure polymerization, and then cut to a required size. Efficiency can be increased and costs can be reduced.

According to the third aspect, the mold is divided into a bottom portion and a jacket portion, and the jacket portion can be moved up and down, and is demolded by raising the jacket portion after completion of the polymerization.

By dividing the bottom of the mold and the jacket so that the jacket can be moved up and down, the molded product can be easily removed from the mold and the production efficiency can be increased.

Next, in a fourth aspect, the core material is set using a core material guide which is fixed to the core material and abuts on the mold.

By setting the core in a mold using a guide, the exact position of the core in the polyamide can be ensured.

[Brief description of the drawings]

FIG. 1 is a plan view of a polyamide resin molded article obtained by a production method of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a perspective view of a core used for a polyamide resin molded body.

FIG. 4 is a perspective view showing another example of a core material.

FIG. 5 is a cross-sectional view of a manufacturing apparatus used in the manufacturing method of the present invention, in which a core is set and a lactam is cast.

FIG. 6 is a cross-sectional view showing a state where polymerization is performed by a manufacturing apparatus used in the manufacturing method of the present invention.

FIG. 7 is a cross-sectional view showing a state where the mold is removed from a manufacturing apparatus used in the manufacturing method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polyamide resin molded body 2 Core material 3 Through hole 5 Groove part 6 Notch groove 10 Manufacturing apparatus 11 Bottom part 12 Jacket part 13 Pressurization piston 14 Cavity 15 Packing 16 Intermediate molded body 17 Polymerizable lactam liquid 18 Core material guide

Continued on the front page F-term (reference) 4F202 AA29 AD18 AH04 AH12 AM34 CA01 CB01 CB12 CK41 CK52 CQ03 CQ05 4F204 AA29 AD18 AH04 AH12 AM34 EA03 EB01 EB12 EF01 EF27 EF37 EK10 EK13 EK24 AW29 AW18F18 AW29 AW18F WB01 WB18 WC02 WF05 WF27 WK01 WK03

Claims (4)

[Claims] 1. A method of manufacturing a core resin-containing polyamide resin molded article in which a core material is embedded in a molded article, wherein a polymerization apparatus including a mold having an opening on at least one side and a pressure piston inserted into the opening is used. With the core material set in, a polymerizable lactam liquid obtained by adding at least an anionic polymerization catalyst and an anionic polymerization initiator to a substantially anhydrous lactam is poured into a mold, and a pressurizing piston is inserted into the opening and pressurized. -A method for producing a core-containing polyamide resin molded product, comprising heating and polymerizing, and releasing after completion of the polymerization. 2. The method for producing a polyamide resin molded article according to claim 1, further comprising a step of cutting to a predetermined size after demolding. 3. The mold according to claim 1, wherein the mold is divided into a bottom portion and a jacket portion, and the jacket portion is movable up and down, and the mold is released by raising the jacket portion after completion of polymerization. A method for producing a polyamide resin molded article containing a core material according to the above. 4. The method for producing a polyamide resin molded product containing a core material according to claim 1, wherein the core material is set using a core material guide that is fixed to the core material and abuts on the mold.