JPS63256644A - Thermoplastic polyester resin filled with metal or the like excellent in dimensional stability and its production - Google Patents

Abstract

PURPOSE:To make it possible to form a thermoplastic polyester resin composition which can give a high-precision molding which does not decrease in strength even upon absorption of moisture, by mixing a surface-treated metal powder or the like with a mixture of a thermoplastic polyester resin with a rubber graft styrene resin. CONSTITUTION:This resin composition is formed from 80-92wt.% surface- treated metal or metal oxide powder and 20-8wt.% mixture (95:5-20:80wt.%) of a thermoplastic polyester resin with a rubber graft styrene resin. As said thermoplastic polyester resin, polybutylene terephthalate is desirable. Examples of said metal powders include iron powder, copper powder, brass powder and zinc powder. Examples of said metal oxide powders include iron oxide powder, etc. As said surface treating agents, a silane coupling agent and a zircoaluminate coupling agent are desirable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Al Industrial Field of Application) The present invention relates to a high specific gravity composition filled with a high concentration of metal powder, etc., and a method for producing the same. Flywheels used for etc.
It is used for parts of micro motors, etc.

(b) Conventional technology Iron powder and brass powder are used at higher concentrations (e.g., weight ratio 70~
High specific gravity compositions containing iron oxide (80%) exist and are molded into parts such as flywheels by injection molding, and compositions containing high concentrations of iron oxide are magnetized during or after the injection molding process. It is used in parts of micro motors, etc.

The plastic components used in such molding materials are mostly polyamide resins (nylon 6, nylon 66).
, nylon LL nylon 12, etc.) are used.

However, the disadvantage of using nylon 6 and nylon 66 is that the resin has a high water absorption rate, so although it maintains high strength in a dry state, it gradually absorbs moisture during actual use and absorbs moisture from the atmosphere. In the equilibrium state, the tensile strength decreases to less than half.

In order to improve these drawbacks, other polyamide resins such as nylon 11 and nylon 12, which have low water absorption rates, are sometimes used, but these materials are extremely expensive and cannot be applied to industrial parts that are used in large quantities. It's difficult.

In order to improve the drawbacks of using nylon resin,
Attempts have been made to use thermoplastic polyester resins, particularly polybutylene terephthalate, as the resin component, and the mechanical strength of the composition exhibits stable behavior unaffected by moisture absorption.

However, since polybutylene terephthalate has a high degree of crystallinity, it is extremely difficult to obtain a highly accurate molded product due to deformation and warpage of the molded product due to differences in molding shrinkage rate depending on the direction of the molded product.

The above-mentioned drawbacks of conventional materials significantly restrict the industrial adoption of this type of material, and therefore there has been a strong demand for improvement of these drawbacks.

(C) Problems to be Solved by the Invention As mentioned above, compositions containing high concentrations of metal powder in the prior art have low strength when moisture is absorbed with polyamide resin, and high-precision molded products can be obtained with polybutylene terephthalate resin. It was difficult.

This invention was made with the aim of improving the above-mentioned drawbacks of the prior art and developing a high-performance metal powder-filled composition with a high concentration, and this invention has been completed.

(d) Means for Solving the Problems The structure of the thermoplastic polyester composition filled with metal powder etc. and the method for producing the same according to the present invention will be explained in detail below.

The composition according to the present invention consists of: (1) 80 to 92% by weight of metal powder or metal oxide powder whose surface has been treated with a silane coupling abrasion or zircoaluminate coupling agent; (9515% by weight of thermoplastic polyester resin and rubber-grafted styrene resin) % to 20/80% by weight of a mixture of 20 to 8M.

As the metal powder used in the composition according to the present invention, reduced iron powder (pulverized), atomized iron powder, or atomized copper powder is used for high specific gravity molded products such as flywheel molded products.
For plastic magnets, oxides of iron group elements called ferrites are generally used.

A requirement of the present invention is that the metal powder or metal oxide powder is first surface-treated to improve its affinity with the resin. For this purpose, organosilane compounds such as γ-aminopropyltriethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N
-phenyl-γ-aminopropyltrimethoxysilane,
A silane coupling agent such as γ-glycitoxypropyltrimethoxysilane or a zircoaluminate camping agent having an organic ligand such as carboxy, aliphatic or methacryloxy as an organic functional group can be used. Among these, aliphatic zircoaluminate coupling agents are particularly effective.

Power, 7 Pulling agent is 0.001 to 2 for metal powder etc.
, 0% by weight, preferably 0.01 to 1.0% by weight is particularly effective.

If the amount is less than this, the effect will be poor, and if more than this is added, the cost will only increase and no improvement in the effect will be seen.

A typical thermoplastic polyester resin used in the present invention is polybutylene terephthalate (PBT). This is terephthalic acid and butylene glycol (also known as 1
・It is obtained by polycondensation with 4-butanediol) and is widely available on the market.

The polybutylene terephthalate used in the present invention includes not only simple polymers but also those blended with various modifiers. An example of this modifier is an impact modifier, and it is known that a modified polyolefin in which an unsaturated carboxylic acid is grafted onto an ethylene or ethylene-propylene copolymer is used. Furthermore, polybutylene terephthalate contains 20 to 50 mol%, preferably 30 to 40 mol%, of a chain tribasic acid component, such as azelaic acid, sebacic acid, dimer acid, cyclohexanedicarboxylic acid, based on the starting material terephthalic acid. A copolyester obtained by copolymerizing the following can be blended. The effect is that this copolyester softens at a lower temperature than PBT, improves the dispersion state of metal powder, lowers the viscosity of the molten material, and improves processability.

The blending ratio is 0 to 10% by weight, preferably 0.5 to 2.
It is 0 weight it%. If the blending ratio is higher than this, the strength and rigidity of the composition will decrease.

The rubber grafted styrenic resin used in the present invention includes styrene-acrylonitrile grafted polybutadiene resin,
Alternatively, styrene-methyl methacrylate grafted polybutadiene resin is representative.

This graft polymer is produced by first producing polybutadiene emulsilane by emulsion polymerization of butadiene, then adding a mixed monomer of styrene and acrylonitrile or a mixed monomer of styrene and methyl methacrylate, stirring,
Continuing heating, these monomers are graft-polymerized onto polybutadiene.

As the rubber component, butadiene-styrene rubber can also be used. In addition, various substituted styrene derivatives such as α-methylstyrene, p-methylstyrene, and 0-chlorostyrene can be used for all or part of the styrene. or,
In addition to acrylonitrile and methyl methacrylate, vinyl monomers that copolymerize with styrene include methyl acrylate, 2-hydroxyethyl methacrylate, acrylic acid,
Examples include methacrylic acid, maleic anhydride, vinyl acetate, and 2-chlorovinyl ether, and two or more of these can be used simultaneously.

Thermoplastic polyester and rubber-grafted styrene thread axis (in order to bring out the characteristics of each fat and achieve maximum performance as a composite resin system, thermoplastic polyester should be used as a continuous phase and rubber-grafted styrene-based resin should be used as a dispersed phase. It is preferable to mix them so that

This is achieved by blending the thermoplastic polyester and the rubber-grafted styrenic resin in a ratio of 9515 to 20/80% by weight, preferably 90/10 to 40/60% by weight.

The morphology of the thermoplastic polyester and rubber-grafted styrene resin mixture was simply confirmed by immersing the molded product in a solvent. When molded products were immersed for 1 hour in acetone, where thermoplastic polyester does not dissolve but styrene resin dissolves, it was found that when the blending ratio of thermoplastic polyester/styrene resin was between 95/20 and 40/60, the molded products did not dissolve. The behavior of the molded product was substantially the same as that of a molded product made of a pure thermoplastic polyester resin.

Therefore, it can be said that the thermoplastic polyester constitutes the continuous phase. When this ratio is between 30/70 and 20/80, the molded product will be softer than a molded product made from a pure composition, but will not melt and lose its shape like a rubber grafted styrene resin. It is therefore clear that the thermoplastic polyester still constitutes the continuous phase.

In such a dispersion system, the anisotropy of molding shrinkage is alleviated due to the effect of the rubber-grafted styrene resin in the dispersed phase, which is effective in producing molded products with good dimensional accuracy and less warpage. Furthermore, as mentioned above, since the thermoplastic polyester is a continuous phase, the heat resistance, lubricity, and oil resistance can maintain the same performance as thermoplastic polyester.

The composition according to the present invention may be added with an antioxidant, for example, a phenolic antioxidant such as tetraester-type hindered phenol, or tetrakis(2,4-di-t-butylphenol)-4,4''- 0.01 to 5% by weight of phosphorous antioxidants such as biphenylene phosphite,
Preferably, it is blended in an amount of 0.1 to 2% by weight to prevent thermal deterioration during molding and actual use.

Furthermore, in order to prevent deterioration of polybutylene terephthalate due to metal powder, a heavy metal deactivator can be added.

Examples of the heavy metal deactivator include 3 (N-salicyloyl)amino 1,2.4) lyazole, or N.

By blending 0.01 to 5%, preferably 0.1 to 2%, of N-bis(3-(3,5-di-t-butyl-4-hydroxylphenyl)propionyl)hydrazine to the resin, significant A stabilizing effect can be obtained.

In addition, a lubricant or a mold release agent may be added to this composition in order to control material deterioration due to excessive shear heat generation during the plasticization and kneading process and to improve the releasability of the molded product from the mold. I can do it.

For this purpose, lubricants such as stearic acid, methylene bis stearamide, montan acid wax, and low molecular weight polyethylene are added to the composition in an amount of 0.01 to 2 Bi%, preferably 0.05 to 0.5iii. % is effective.

In addition, depending on the required performance of the product made from the composition, lubricants and antifriction agents such as silicone oil, graphite, molybdenum disulfide, and polytetrafluoroethylene powder may be added to the composition.
．． It can also be blended in an amount of 1 to 20% by weight, preferably 2 to 10% by weight.

The composition according to the present invention is melt-kneaded using a single-screw extruder, a twin-screw extruder, an extruder equipped with a kneading mechanism, etc. in a conventional manner, formed into pellets, and then formed into pellets using an injection molding machine in a conventional manner. It can be molded using

As another method for producing the composition according to the present invention, the present composition is mixed at high speed with a high-speed mixer such as a Henschel mixer, and the copolyester in the blend is melted by frictional heat generation, and the copolyester is mixed with metal powder etc. By creating a mixture in which PBT and ABS powder are uniformly mixed and fused together, and then melting and mixing this in an injection molding machine and injection molding, a plastic molded product filled with a high concentration of metal powder or metal oxide is manufactured. This is the way to do it.

In carrying out this method, an ordinary screw in-line type injection molding machine can be used, but a structure in which the screw has a dispersion function, such as a pin type or a gear set structure, can also give better effects.

Furthermore, the mechanism described in Japanese Patent No. 1104727 can also provide extremely good results.

In the injection molding of the composition according to the present invention, a material supply device that operates in conjunction with the screw of the injection molding machine is attached, and the material is adjusted to be supplied into the cylinder of the molding machine in a starvation state. First, it is preferable to mold it.

This effect is due to the fact that the material is sufficiently aerated and the high viscosity material during the melting process does not hinder the advance of the screw during injection, so the screw moves within the set stroke. This is because it is extremely effective in manufacturing precision molded products by smoothly advancing according to the combination of position and injection speed.

However, the composition itself according to the present invention is of course not limited by this manufacturing method.

te1 effect The present invention improves strength and dimensions by using a polybutylene terephthalate resin in which rubber-grafted styrene resin is dispersed as a matrix in a thermoplastic polyester resin composition containing a high concentration of metal powder or metal oxide powder. It has the effect of providing molded products with excellent precision. By blending the copolyester resin into the present composition, the blending and molding processes are facilitated, and highly accurate molded articles can be molded.

Furthermore, the present invention has also developed a method for producing molded articles of the composition with high dimensional accuracy.

(flExample) The structure of the present invention will be specifically explained with reference to Examples below.

Example 1 (1) Iron powder with an average particle size of 200 mesh made by the atomization method (K I P2O3A manufactured by Kawasaki Steel, specific gravity 7.
85) While mixing 5000 g at low speed in a high-speed mixer (Super Mixer manufactured by Kawasaki Steel Corporation), add a zircoaluminate coupling agent (CA manufactured by CAVDONCHEM).
VCOMOD F) 25g and denatured alcohol 125g
A mixed solution was added thereto, and mixing was continued for 30 minutes at 750 r/n+, and the temperature was raised to 100° C. to bring out the alcohol content to obtain treated iron powder.

(2) Continue with powdered polybutylene terephthalate resin (
Duranex 2002 manufactured by Polyplastics (pulverized product) 530g, ABS resin (Sevian 300 powder manufactured by Daicel Chemical Industries, Ltd.) 350g, hindered phenol type antioxidant (AO-6 manufactured by Adeka Argus)
0) 5g, heavy metal deactivator (mark ODA-1, manufactured by Adeka Argus), 5g, and 15g of copolyester resin (Vylon 103, manufactured by Toyobo Co., Ltd.) were added and 750r/
Mixed for 30 minutes at m. The temperature of the mixture rose to 150° C. and the copolyester resin melted.

(3) Continue cooling the mixer jacket with water for 10 minutes.
Continue mixing at 0r/m for 20 minutes to mix iron powder, PBT, and ABS.
A granular mixture of fused powder was obtained.

(4) Transfer this mixture to an injection molding machine equipped with a melt kneading mechanism described in Japanese Patent No. 1104727 from a screw feeder interlocking with a screw so that the supply section in the molding machine cylinder is in a starved state. The mixture was fed and molded.

Comparative Example 1 A mixture was made in the same manner as in Example 1, except that no ABS resin was added, the amount of polybutylene terephthalate resin was increased to 880 g, and the mixture was molded in the same manner.

Table 1 shows the molding conditions for the materials of Example 1 and Comparative Example 1. The molds used for molding were ASTM D6384 type tensile test pieces and ASTM D790 bending test pieces (wall thickness 3.21 mm).

Table 1. As shown in Table 2, the material of Example 1 is superior in both tensile strength and bending strength.

Table 2. Physical property measurement results Dimensional accuracy test The same injection molding machine as in section (3) was used, and the mold was a disk-shaped mold with a diameter of 47 wmφ and an average wall thickness of 6.0+++m, with a bottle hole (2.5 msφ) in the center. The gate is a three-point pin gate arranged symmetrically around the center. The molding conditions are shown in Table 3. Table 4 shows the measurement results of 10 arbitrary shots out of 50 continuous shots.

The measurement was carried out after adjusting the tq of the molded product at 23° C. and 50% RH.

Example 1 has much better dimensional accuracy than Comparative Example 1.

Table 3 Molding conditions fg) Effects of the invention This invention was developed as a resin composition filled with a high concentration of total bending powder, etc., to solve the deformation and warpage of molded products, which are the drawbacks of polybutylene terephthalate resin. Series resin 9515 to 20/8
This is a significant improvement by using a mixture of 0.0% by weight, and its industrial value is great.

Furthermore, an efficient method for producing the composition has also been completed.

Claims (12)

[Claims] (1) Surface-treated metal powder or metal oxide powder 8
0 to 92% by weight, and 20 to 8% by weight of a 95/5 to 20/80% by weight mixture of thermoplastic polyester resin and rubber-grafted styrene resin. (2) The composition according to claim 1, wherein the metal powder is iron powder, copper powder, brass powder, or zinc powder. (3) The composition according to claim 1, wherein the metal oxide powder is iron oxide powder. (4) The composition according to claim 1, wherein the thermoplastic polyester is polybutylene terephthalate. (5) The composition according to claim 1, wherein the rubber-grafted styrene resin is an ABS resin. (6) The composition according to claim 1, wherein the rubber-grafted styrenic resin is an MBS resin. (7) Thermoplastic polyester resin is 20 to 50 mol%
The composition according to claim 1, which is a composition containing 0 to 10% by weight of a copolyester obtained by copolycondensation of a chain dibasic acid component. (8) The composition according to claim 1, wherein the metal powder or metal oxide powder is surface-treated with a silane coupling agent. (9) The composition according to claim 1, wherein the metal powder or metal oxide powder is surface-treated with a zircoaluminate coupling agent. (10) A method for producing a plastic composition filled with a high concentration of metal powder, etc., which comprises molding a powder mixture using a screw-in-line injection molding machine when producing the composition according to claim 1. (11) The method for producing a composition according to claim 10, wherein the injection molding machine is a molding machine equipped with a kneading mechanism described in Japanese Patent No. 1104727. (12) The mixed material according to claim 10 is characterized in that a material supply device that operates in conjunction with a screw of the injection molding machine supplies the mixed material so that the feed section of the molding machine cylinder is starved. Method for producing the composition.