JPH11207754A - Production of polyamide resin molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an polyamide resin molding which is light in weigh, can be used over a long period without supplying oil and demolded easily, reduces the shortage of polymerization and the generation of sink marks, and maintains bond strength between the resin and a reinforcing material. SOLUTION: A support base 13 is installed freely movably to the bottom surface 21 of a temperature-adjustable lower mold, and a reinforcing plate 2 is fixed on the support base 13. A polymerizable lactam liquid in which a substantially anhydrous ω-lactam is added with at least an anionic polymerization catalyst and an anionic polymerization initiator is packed in the lower mold to the full, after the lactam liquid being sealed with a shielding material 19 not to allow air to exist on the surface of the lactam liquid, an upper lid 16 is mounted for polymerization, and a molding 1 is demolded after the completion of polymerization.

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, and more particularly, to a polyamide resin molded article having a reinforcing material for gears, rollers, wheels and the like 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 molded article 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 method has been proposed in which only the boss portion is made of metal while taking advantage of the characteristics 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. Also, a method of cold-pressing the polyamide resin portion into a metal subjected to knurling, heating the metal, and fusing and integrating the polyamide resin portion and the metal,
It is disclosed in Patent No. 2622813.

[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 is weak, and a gap may occur between the metal boss portion and the polyamide resin portion in a short period of 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. Furthermore, when the molded article was released after the polymerization was completed, the mold was turned upside down.However, the molded article was sometimes hugged by the support, and it took time to remove the molded article. Was.

The present invention solves these problems, and makes use of the advantages of polyamide resins, is lightweight, can be used for a long time without lubrication, facilitates demolding of polyamide resin molded articles, and causes 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.

[0009]

According to a first aspect of the present invention, there is provided a method for manufacturing a polyamide resin molded article in which a polyamide resin is bonded to and integrated with a reinforcing plate around a reinforcing plate. It is movably installed with respect to the bottom of the mold, and the reinforcing plate is fixed to the above-mentioned support base, and the substantially anhydrous ω-
The lactam was filled with a polymerizable lactam liquid obtained by adding at least an anionic polymerization catalyst and an anionic polymerization initiator to the extent that it overflowed into the mold, and the shielding material was sealed so that air did not intervene on the liquid surface of the polymerizable lactam liquid. After that, polymerization is performed by installing an upper lid, and after the polymerization is completed, the molded product is released from the mold.

According to the present invention, since the supporting base for fixing the reinforcing plate is movably installed with respect to the bottom surface of the mold, the mold is turned upside down and the supporting base is moved by weight, thereby forming. As a result, the molded body can be released by its own weight, and the upper lid is installed after sealing the shielding material so that air does not intervene on the surface of the polymerizable lactam liquid. Due to polymerization, insufficient polymerization and sink marks on the surface can be prevented, and surface processing can be performed in a short time. Then, the obtained polyamide resin prevents the residual shrinkage stress generated during polymerization and uniformly shrinks, thereby satisfactorily embracing with the reinforcing plate and also being mechanically locked, so that the polyamide resin is removed from the reinforcing plate. It does not come off easily.

The invention according to claim 2 of the present application resides in a method for manufacturing a polyamide resin molded body in which a support stand is installed so as to be movable by a predetermined length only in a direction perpendicular to the bottom surface of a mold. Since the support does not move freely from the bottom surface of the mold during molding, it is possible to prevent the support from rolling when the molded product is released from the mold.

According to a third aspect of the present invention, there is provided a method of manufacturing a polyamide resin molded article in which a support stand can be fitted to a protrusion provided on a bottom surface of a mold, and the protrusion serves as a mark for an installation position of the support stand. , The support can be mounted instantly.

The invention according to claim 4 of the present application resides in a method for producing a polyamide resin molded article in which the reinforcing plate has one groove-shaped portion or a convex portion along the circumferential direction of the side surface. The resin prevents shrinkage stress generated during polymerization from remaining, and shrinks uniformly, so that it is well hugged with the reinforcing plate,
Further, since the polyamide resin is mechanically locked, the polyamide resin does not easily come off the reinforcing plate.

According to a fifth aspect of the present invention, there is provided a method for producing a polyamide resin molded article, wherein the reinforcing plates are provided at predetermined intervals along the circumferential direction and have notches for preventing rotation in the thickness direction. Yes, the polyamide resin does not easily come off the reinforcing plate, and the polyamide resin does not easily rotate from the reinforcing plate, so that the bonding strength between the polyamide resin and the reinforcing plate is high, and it can be applied to gears, rollers, wheels, etc. it can.

The invention according to claim 6 of the present application resides in a method for producing a metal-reinforced polyamide resin molded article provided with a liquid reservoir for recovering a polymerizable lactam liquid overflowing from a mold on the outer periphery of the mold. The polymerizable lactam liquid overflowing from the mold can be easily collected and does not pollute the working environment.

The invention according to claim 7 of the present application is a method for producing a polyamide resin molded article in which the inner wall surface of the mold is tapered so that the molded article can be easily removed from the molded article. Has become.

The invention according to claim 8 of the present application is a method for producing a metal-reinforced polyamide resin molded article in which the shielding material is a metal foil, and can be reliably sealed with the metal foil.

[0018]

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. FIG. 4 is a perspective view of a reinforcing plate used, and FIG. 4 is a perspective view of another reinforcing plate used in the polyamide resin molded article of the present invention.

The polyamide resin molded article 1 manufactured 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 as shown in FIG. One groove-shaped portion 5 is provided along the circumferential direction, and at a predetermined interval along the circumferential direction, and outside the metal reinforcing plate 2 having a cutout groove 6 for preventing rotation along the thickness direction. It has a structure in which a polyamide resin 9 is mounted. A tooth portion (not shown) is formed on the outer peripheral portion of the polyamide resin 9 by subsequent machining, and is used as a gear for high load. At the time of subsequent processing, the through hole 3 is attached to the grip portion of the lathe.

1. As the other reinforcing plate 2, as shown in FIG. 4, a through hole 3 is provided at the center, one convex portion 7 is provided along the circumferential direction of the side surface 4, and a predetermined portion is provided along the circumferential direction. It may be a shape having notches 6 at intervals and along the thickness direction for preventing rotation. The one groove portion 5 and the convex portion 7 prevent the residual of the shrinkage stress generated during the polymerization of the polyamide resin and uniformly shrink, whereby the polyamide resin is well hugged with the reinforcing plate 2 and is mechanically locked. Therefore, the polyamide resin 9 is
Does not escape easily from The notch 6 prevents the polyamide resin 9 from rotating from the reinforcing plate 2.

FIG. 5 is a cross-sectional view showing a reinforcing plate installed in a mold in the manufacturing method of the present invention, FIG. 6 is an enlarged view of a portion B in FIG. 5, and FIG. 7 is a polymerization cast in the manufacturing method of the present invention. FIG. 8 is a cross-sectional view in which the surface of the hydrophilic lactam liquid is sealed with a shielding material, FIG. 8 is a cross-sectional view in which polymerization is performed with an upper lid in the production method of the present invention, and FIG. FIG.

As shown in FIGS. 5 to 7, a mold 10 used for manufacturing the above-mentioned polyamide resin molded body 1 is provided in a cavity 12 of a lower mold 11 made of aluminum, iron or the like and having a high thermal conductivity. A support base 13 for inserting and fixing the through hole 3 of the reinforcing plate 2 is provided at the center, and a groove-shaped liquid reservoir 15 continuously arranged along the outer peripheral wall 14 overflows from the lower mold 11. The recovered polymerizable lactam liquid is collected to prevent contamination of the working environment. The upper lid 16 is installed on each head of the outer peripheral wall 14 and the support base 13.

The support table 13 is installed so as to surround a column 22 inserted and fixed to the bottom surface 21 of the outer mold 11. Then, a pair of protruding stoppers 23 provided on the bottom of the support 13 are fitted into two guide grooves 24 provided along the longitudinal direction of the column 22, and the support 13 is perpendicular to the bottom 21. It becomes movable by a predetermined width. At the upper limit position of the support 13, the stopper 23 comes into contact with the locking portion 25 and stops, and at the lower limit position, the support 13 comes into contact with the bottom surface 21. The wall thickness of the support base 13 and the outer peripheral wall 14 is 0.5 to
It has a 7 ° taper surface, making it easier to remove the polyamide resin molded article 1 from the mold. The support 13 can be fitted to a protrusion (not shown) provided on the bottom surface 21 of the lower mold 11, and the support 13 can be attached instantaneously using the protrusion as a mark.

Thus, the through hole 3 of the reinforcing plate 2 is
3 and the reinforcing plate 2 is stably installed on the lower mold 11,
Hot plate 1 in which lower mold 11 is temperature-controlled at 100 to 180 ° C
After that, the polymerizable lactam solution obtained by adding at least an anionic polymerization catalyst and an anionic polymerization initiator to substantially anhydrous ω-lactam is filled to the extent that it overflows into the lower mold 11. At this time, the overflowing polymerizable lactam liquid is stored in the liquid reservoir 15.

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

Subsequently, the shielding material 19 is sealed on the surface of the polymerizable lactam liquid so that no air is interposed therebetween.
6 is set and polymerized. The shielding material 19 used here is preferably a metal foil represented by an aluminum foil. When the polymerization is completed, the upper lid 16 is removed, and when the lower mold 11 is inverted, the polymerized polyamide resin molded body 1 moves together with the support 13 and separates from the lower mold 11 to drop. The unreacted liquid monomer did not remain on the upper surface 21 of the polyamide resin molded body 1, and the polyamide resin molded body 1 having a good appearance was obtained.

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

Further, the anionic polymerization catalyst used in the present invention includes sodium hydride, lithium hydride, sodium,
Known polymerization catalysts for ω-lactams such as potassium can be used, and the amount added is 0.1 to ω-lactam.
~ 2.0 mol%. Examples of the anionic polymerization initiator include N-acetyl-ε-caprolactam, isocyanate, diisocyanate, urea derivative, urethane, and isocyanurate derivative.
The range of 0.05 to 1.0 mol% with respect to the lactam is preferred.

In the above production method, the anionic polymerization catalyst
A method of adding and mixing an anionic polymerization initiator after or after adding and dissolving to a lactam, or a method of casting an ω-lactam containing an anionic polymerization catalyst and an ω-lactam containing an anionic polymerization initiator. Alternatively, it is adjusted by a method of adding and mixing after casting. Further, the polymerization of ω-lactam can be carried out at a temperature of 100 to 210 ° C., preferably 130 to 180 ° C.

In carrying out the method of the present invention, oils, waxes, zinc stearate, calcium stearate and the like, which do not inhibit polymerization, and reinforcing materials such as carbon fiber and glass fiber are added in addition to the above components. Is also possible.

[0031]

The present invention will be described in more detail with reference to the following examples. Example 1 After dehydration, ε-caprolactam in a dehydration tank was weighed and put into two casting tanks, and after putting 1,250 g into one casting tank and 1,250 g into the other casting tank, 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 solution was mixed while the temperature was raised to 125 ° C. while flowing nitrogen in the casting tank under atmospheric pressure.

An iron lower mold (with an inner diameter of 95 m) in which a support table as shown in FIG.
m, a depth of 23 mm) on a hot plate set at 170 ° C., a through hole in the center as shown in FIG. 3, one groove along the circumferential direction of the side surface, and a circumferential direction. And a reinforcing plate made of iron having four notch grooves for preventing rotation along the thickness direction was placed in the lower mold. Then, after pouring the mixed polymerizable lactam liquid into the lower mold until it overflows, after sealing the shielding material made of aluminum foil so that air does not intervene on the liquid surface of the polymerizable lactam liquid, install the upper lid. Polymerized.

When the polymerization was completed, the upper lid was removed, the lower mold was cooled to 100 ° C., and then the lower mold was turned over. When the lower mold was inverted, it was easily removed from the lower mold and the support base by the weight of the polyamide resin molded article. An unreacted liquid monomer did not remain on the upper surface of the molded product, and a polyamide resin molded product having a good appearance without any local sink was obtained.

Further, a test for removing a reinforcing plate from the molded polyamide resin molded article was performed. In the test for removing the reinforcing plate, the polyamide resin molded body was placed on a support stand of an autograph at environmental temperatures of -40 ° C, 20 ° C, and 100 ° C, and the reinforcing plate was removed while pressing the reinforcing plate. The amount and stress were determined, and the stress when the reinforcing plate came off was determined. As a result, the reinforcing plate did not come off at 50 kN at −40 ° C. and 20 ° C., but at 100 ° C., the polyamide resin came off without breaking at 40 kN. However, it was confirmed that all had good bonding strength.

Example 2 A recess provided on the support was fitted to a projection provided at the center of the lower mold, and the support was set on the lower mold.
After being placed on the hot plate set in the above, a through hole in the center as shown in FIG. 3, one groove-shaped portion along the circumferential direction of the side surface, and a predetermined interval along the circumferential direction, and An iron reinforcing plate having four notch grooves for rotation prevention along the thickness direction was installed in the lower mold. Then, after pouring the mixed polymerizable lactam solution into the lower mold until it overflows in the same manner as in Example 1, a shielding material made of aluminum foil is sealed on the liquid surface of the polymerizable lactam solution so that air does not intervene. ,
The top lid was placed and polymerization was carried out.

When the polymerization is completed, the upper lid is removed, the lower mold is cooled to 100 ° C., and then the lower mold is inverted. Demolded. An unreacted liquid monomer did not remain on the upper surface of the molded product, and a polyamide resin molded product having a good appearance without any local sink was obtained.

COMPARATIVE EXAMPLE 1 After a reinforcing plate was placed on an iron lower mold having a support fixed to the bottom surface, a polymerizable lactam solution was poured into the lower mold as in Example 1 until it overflowed, as in Example 1. The film was sealed with a shielding material made of aluminum foil, placed on the top lid, and polymerized. When the polymerization was completed, the upper lid was removed, and the lower mold was cooled to 100 ° C. When the lower mold was inverted, the polyamide resin molded body stuck to the support base and did not fall by its own weight.

Comparative Example 2 An iron lower die having a support fixed to the bottom was used. Example 1
The polymerizable lactam liquid was poured into the lower mold without overflowing into the lower mold containing the same reinforcing plate as described above, then sealed with a shielding material made of aluminum foil, and the upper lid was placed for polymerization. Unreacted liquid monomer remained on the upper surface of the obtained polyamide resin molded body, and a plurality of sink marks having a depth of about 10 mm were generated, resulting in poor appearance.

Comparative Example 3 A polymerizable lactam solution was poured into a lower mold containing a reinforcing plate similar to that of Example 1 in an overflowing state, and the upper lid was sealed without being sealed with a shielding material made of aluminum foil. Placed and polymerized. Unreacted liquid monomer remained on the upper surface of the obtained polyamide resin molded product, and again sink marks with a depth of about 10 mm occurred.

[0040]

As described above, according to the first aspect of the present invention, since the support base for fixing the reinforcing plate is movably installed with respect to the bottom surface of the mold, the mold is inverted and supported. By moving the platform by weight, the molded body is forcibly released from the mold, which allows the molded body to be released by its own weight, and further shields the liquid surface of the polymerizable lactam liquid from air. Since the material is sealed and the upper lid is set to perform polymerization, insufficient polymerization of the surface and generation of sink marks can be prevented, and surface processing can be performed in a short time. Then, the obtained polyamide resin prevents the residual shrinkage stress generated during polymerization and uniformly shrinks, thereby satisfactorily embracing with the reinforcing plate and also being mechanically locked, so that the polyamide resin is removed from the reinforcing plate. There are effects such as easy removal.

In the invention according to the second aspect of the present invention, the support base is installed so as to be movable by a predetermined width only in the vertical direction with respect to the bottom surface of the mold. Since it does not move freely from the mold, it is possible to prevent the support base from rolling when the molded body is released from the mold.

According to the third aspect of the present invention, since the support can be fitted to the protrusion provided on the bottom surface of the mold, the protrusion serves as a mark of the installation position of the support, and the support can be mounted instantaneously. Can be.

In the invention according to claim 4 of the present application, since the reinforcing plate has one groove portion or convex portion along the circumferential direction of the side surface, the obtained polyamide resin has shrinkage generated during polymerization. By preventing the residual stress and uniformly shrinking, the resin is firmly hugged with the reinforcing plate, and is mechanically locked, so that the polyamide resin does not easily come off from the reinforcing plate.

According to the fifth aspect of the present invention, since the reinforcing plate is provided at predetermined intervals along the circumferential direction and has cutout grooves for preventing rotation in the thickness direction, the polyamide resin can be removed from the reinforcing plate. The polyamide resin does not easily come off, and the polyamide resin hardly rotates from the reinforcing plate, so that the bonding force between the polyamide resin and the reinforcing plate is high, and the polyamide resin can be applied to gears, rollers, wheels, and the like.

The invention according to claim 6 of the present application resides in a method for producing a metal-reinforced polyamide resin molded article, wherein a liquid reservoir for recovering a polymerizable lactam liquid overflowing from a mold is provided on the outer periphery of the mold. The polymerizable lactam liquid overflowing from the mold can be easily collected and does not pollute the working environment.

The invention according to claim 7 of the present application is a method for producing a polyamide resin molded article in which the inner wall surface of the mold is tapered so that the molded article can be easily removed from the molded article. Has become.

The invention according to claim 8 of the present application is a method for producing a metal-reinforced polyamide resin molded article in which the shielding material is a metal foil, and can be reliably sealed with the metal foil.

[Brief description of the drawings]

FIG. 1 is a plan view of a polyamide resin molded article according to the present invention.

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

FIG. 3 is a perspective view of a reinforcing plate used in the polyamide resin molded article of the present invention.

FIG. 4 is a perspective view of another reinforcing plate used in the polyamide resin molded article of the present invention.

FIG. 5 is a cross-sectional view illustrating a state where a reinforcing plate is installed in a mold in the manufacturing method of the present invention.

FIG. 6 is an enlarged view of a portion B in FIG. 5;

FIG. 7 is a cross-sectional view in which the surface of a polymerizable lactam liquid cast in the production method of the present invention is sealed with a shielding material.

FIG. 8 is a cross-sectional view showing a state in which polymerization is performed with a top cover in the production method of the present invention.

FIG. 9 is a cross-sectional view showing a state where a molded body is released from a mold in the production method of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Polyamide resin molded body 2 Reinforcement plate 3 Through hole 5 Groove 6 Notch groove 10 Mold 11 Lower mold 12 Cavity 13 Support base 15 Liquid reservoir 16 Top lid 19 Shielding material 21 Bottom 22 Support 23 Stopper 24 Guide groove 25 Stop

Claims (8)

[Claims] 1. A method for producing a polyamide resin molded body in which a polyamide resin is bonded to and integrated around a reinforcing plate,
A support is movably installed with respect to the bottom surface of the mold whose temperature can be adjusted, a reinforcing plate is fixed to the support, and at least an anionic polymerization catalyst and an anionic polymerization initiator are added to substantially anhydrous ω-lactam. Fill the polymerizable lactam liquid to the extent that it overflows into the mold, seal the shielding material so that air does not intervene on the liquid surface of the polymerizable lactam liquid, install the top lid, polymerize, and complete the polymerization. A method for producing a polyamide resin molded article, comprising removing the molded article after the molding. 2. The method for producing a polyamide resin molded article according to claim 1, wherein the support base is installed so as to be movable by a predetermined length only in a direction perpendicular to a bottom surface of the mold. 3. The method for producing a polyamide resin molded article according to claim 1, wherein the support base can be fitted to a projection provided on the bottom surface of the mold. 4. The reinforcing plate has one groove-shaped portion or a convex portion along the circumferential direction of the side surface.
The method for producing a polyamide resin molded article according to the above. 5. The method for producing a polyamide resin molded article according to claim 4, wherein the reinforcing plate is provided at predetermined intervals along a circumferential direction and has cutout grooves for preventing rotation in the thickness direction. 6. The method for producing a polyamide resin molded article according to claim 1, wherein a liquid reservoir for recovering the polymerizable lactam liquid overflowing from the mold is provided on the outer periphery of the mold. 7. The method for producing a polyamide resin molded article according to claim 1, wherein an inner wall surface of the mold has a tapered surface so that the molded article can be easily removed from the molded article. 8. The method according to claim 1, wherein the shielding material is a metal foil.