JPH02252536A - Moldings of resin and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain moldings of resin in which separation of inorganic fillers and resin does not occur by forming moldings of resin from composite materials composed of inorganic fillers, resins, and coupling agents at a specific ratio. CONSTITUTION:A molding of resin contains base resins composed of thermoplastic resins having a molecular weight of 50000-1000000, addition resins composed of resins having a molecular weight of 1000-50000, inorganic fillers, and coupling agents. The ratios between the components are such that 0.5-100 pts.wt. of addition resins to 100 pts.wt. of base resins, 0.1-10.0 pts.wt. of coupling agents to 100 pts.wt. of base resins, and 5-200 pts.wt. of inorganic fillers to 100 pts.wt. of total of base resins and addition resins. When injection molding is conducted using these materials, even in the case of short-time molding, separation of inorganic fillers and resins does not occur, resulting in obtaining uniform moldings of resins. When molecular weight of the base resins is smaller than 50000-1000000, strength of moldings can not be maintained and when said molecular weight is larger than said values, fluidity thereof becomes low. When molecular weight of the addition resins is smaller than 1000-50000, the resins are decomposed and when said molecular weight is larger than said values, fluidity of the composite materials is not improved, with the result that the inorganic fillers are separated on the surface of the molding.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resin molded article, particularly a magnetic tape cassette case with improved moldability.

[Conventional technology]

A magnetic tape cassette stores video tapes, audio tapes, etc. and can be used as is for recording and playback, and its case is molded from a resin material.

This cassette case is manufactured by so-called injection molding, in which resin is molten at high temperature and injected into a mold through a jet nozzle.

The cassette case manufactured in this manner not only requires mechanical strength, but also dimensional accuracy and dimensional stability such that the dimensions do not change even after long-term use.

As a resin material that satisfies such requirements, a composite material consisting of 4MHj such as polybrohylene and an inorganic filler such as calcium carbonate having a particle size of 2 to 3 μm is used.

[Problem to be solved by the invention]

However, when injection molding is performed using the above-mentioned composite material, shear stress is generated in the ejected material when the molten material of the composite material is ejected from the injection nozzle of the injection molding machine, and heat generation also occurs. If you try to increase the jet speed from the jet nozzle and mold in a short time, these will become significantly larger.
This makes it easy for the resin and the inorganic filler to separate, resulting in a phenomenon in which the inorganic filler is deposited on the surface of the molded article. When this happens, the material becomes non-uniform, making it impossible to increase mechanical strength, and also impairing dimensional accuracy and dimensional stability. In order to avoid this phenomenon, the molding speed must be slowed down, resulting in the problem that productivity cannot be improved.

On the other hand, recently, metal magnetic powder has come to be used in magnetic tapes, making it easier to record in the short wavelength range, so dimensional accuracy and stability are now being strictly required for magnetic tape cartridge cases. improvement is desired.

An object of the present invention is to provide a resin molded article in which an inorganic filler and a resin do not separate.

[Means to solve the problem]

In order to solve the above problems, the present invention has a molecular weight of 5o, o
Contains a base resin consisting of a thermoplastic resin with a molecular ill of 000 to 50,000, an inorganic filler, and a coupling agent, and the proportion of each of these components. is 0.5 to 100 parts by weight of additive resin to 100 parts by weight of base resin, 0.1 to 10.0 parts by weight of coupling agent, and 5 to 200 parts by weight of inorganic filler to 100 parts by weight of base resin and additive resin. An object of the present invention is to provide a resin molded article characterized by parts by weight. Further, injection molding using a composite material having the above composition is preferable because even if the molding is performed for a short time, there is no separation of the inorganic filler and the resin, and a uniform resin molded product can be obtained.

Next, the present invention will be explained in detail.

The base resin made of thermoplastic resin used in the present invention includes polyolefins such as polystyrene, polypropylene and polyethylene, vinyl polymers such as acrylic, AS (acrylonitrile-styrene copolymer), and ABS, as well as polyester, Polyamide etc. can also be used. Its molecular weight is so, oo.

~t, ooo, ooo, and if it is smaller than this range, the strength of the molded product cannot be maintained, and if it is larger than this, the fluidity of the composite material mixed with other inorganic fillers, additive resins, etc. during molding will deteriorate, Undesirable.

Further, examples of the additive resin used in the present invention include those of the same type as the above-mentioned base resin, phenolic resins, epoxy resins, and the like. The same type of base resin and additive resin may be used together, but they may also be used in combination. The molecular q of the additive resin is preferably 1,000 to 50,000, and if it is smaller than this range, molding Sometimes, during heat treatment, this added resin decomposes, making it difficult to obtain the effect of its addition. Also, if it exceeds this range, the fluidity of the composite material consisting of other base resins and inorganic fillers during molding may be affected. There is no improvement, and the inorganic filler tends to precipitate on the surface of the molded product.

The ratio of the base resin and the additive resin used is preferably 0.5 to 100 parts by weight of the latter to 100 parts by weight of the former.If the amount of the additive resin is less than 0.5 parts by weight, the mixture with inorganic fillers etc. When the composite material is melted and molded, the effect of improving fluidity is small, and the inorganic filler tends to separate on the surface of the molded product, and if the amount exceeds 100 parts by weight, the strength of the molded product decreases.

The inorganic filler used in the present invention includes CaCO3
, TiO2,5i02, ZnO, Fe2O3, Cr2O
3,41203, CrO2, Pb3O4%CuO, etc., and the average particle size thereof is preferably 0.1 to 10μ.

The ratio of the inorganic filler to the resin used is 5 to 200 parts by weight per 100 parts by weight of the base resin and additive resin; if it is less than this, the dimensional stability of the molded product may deteriorate; If the amount is more, the resin amount may be too small, which may reduce the bending and tensile strength of the molded product.

As the coupling agent used in the present invention, IM or two or more of a silane cuffing agent, a titanium coupling agent, and an aluminum coupling agent are used. Specifically, the following can be mentioned.

Silane cuffing agent Methyltrimethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-r-aminopropyltrimethoxysilane, T-glycidoxybrobyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane Examples include methoxysilane and hexamethyldisilazane.

Titanium coupling agents include isopropyl trioctanoyl titanate, isopropyl dimethacrylylisostearoyl titanate, isopropyl tri (dioctyl phosphate) titanate, isopropyl tri (N-aminoethylaminoethyl) titanate, and the like.

Aluminum coupling agents include aluminum triisopropylate, ethyl acetoacetate aluminum diisopropylate, aluminum tris (acetylacetonate), cyclic aluminum oxide isopropylate, and the like.

The amount of the coupling agent used is 0.1 to 10.0 parts by weight per 100 parts by weight of the base resin. If the amount is less than this range, the wettability of the inorganic filler to the resin cannot be improved, and the resin and the inorganic filler tend to separate when melting and molding a composite material consisting of the resin, inorganic filler, etc. Moreover, if the amount of the coupling agent is greater than the above range, the strength of the molded article will be lowered, which is not preferable.

Other components such as colorants, lubricants, etc. can also be used in the resin molded article of the present invention and the composite material used to obtain the same.
A masterbatch prepared by mixing colorant and resin in advance can also be used.

In order to produce the resin molded article of the present invention, the resin, an inorganic filler, a coupling agent, and other additives such as a coloring agent, if necessary, are added and then mixed. When mixing the coupling agent, it is also preferable to dissolve it in an organic solvent and then mix it with the inorganic filler, and then mix this mixture with the resin and other components.

A composite material obtained by mixing each component is molded, and examples of this molding method include injection molding.

In addition to magnetic tape cartridge cases, the resin molded product of the present invention can be used in molded products such as guide rollers of magnetic recording devices, tape guide bins, and cases used in precision equipment such as cameras, outer frames of watches, and speaker boxes. It is also used for items that require dimensional accuracy, dimensional stability, strength, etc.

[Effect]

By using a coupling agent in combination with a composite material consisting of an inorganic filler and a resin, the wettability of the inorganic filler to the resin is improved. This improves the dispersibility of the inorganic filler and improves the fluidity of the melt when the composite material is melted and molded.

When the melt is ejected from the ejection nozzle during injection molding, if the fluidity is good, stress generation and heat generation can be suppressed, and separation of the inorganic filler from the resin in the molded product can be suppressed.

In addition, by using a resin with a molecular weight of 1,000 to 50,000 in combination with a base resin with a molecular weight of 50,000 to 1,000,000, it is possible to improve the flow of the melt of the composite material consisting of the resin, inorganic filler, coupling agent, etc. The properties of the molded product can be further improved, the above-mentioned effects can be better exhibited, and the mechanical strength of the molded product can also be maintained.

〔Example〕

Next, the present invention will be explained in detail.

Example 1 Polystyrene (molecular weight 300,000) 80 f
fi parts polystyrene (molecular weight 20,000) 2
0 ffi amount leg calcium carbonate io
o parts by weight (CaCO3 average particle size 2μl 11) masterbatch 5 parts by weight (carbon and resin mixed at 20880) silane cuffing agent z parts by weight (parts by weight of Bi (part by weight of tiltrimethoxysilane)) by heating and melting at 200°C using an extruder. and kneaded to make pellets. The thus obtained pellets were used to mold an audio cassette tape half with an injection molding machine of 100 mm (II bottom) using an injection time of 3 seconds.

The thus obtained halves were subjected to visual inspection and strength tests.

In the appearance inspection, the entire surface of the half was visually inspected, and if even one non-uniform part was observed, the product was judged to have a semi-uniform appearance. In addition, in the strength test, a metal tape with a length of 135 m was installed in the half, and this was dropped from the height of the rim onto a concrete surface, and when damage such as cracks was visually observed, it was considered broken.

The test results for the 100 halves obtained above are shown in Table 1 as the number of pieces regardless of appearance and the number of damaged pieces.

As a result of Table 1, it can be seen that there were no products with half-uniform appearance, and there were no damaged products, and all items were good.

Example 2 Polystyrene (molecular weight 300,000) 80 parts by weight Polystyrene (molecular weight 20,000) 20
Parts by weight Calcium carbonate 100 parts by weight (CaCO5 average particle size 2μ resistant masterbatch 5 parts by weight (carbon and resin mixed at a ratio of 20:80) Silane coupling agent 0.1 parts ffi part part tiltrimethoxysilane) was processed in the same manner as in Example 1 above to obtain a half of 100 fi
These were also tested in the same manner as in Example 1, and the results are shown in Table 1.

As shown in Table 1, even when 0.1 part by weight of the coupling agent was used, all the tests showed good results as in Example 1.

Example 3 Polystyrene (molecular weight 300.000) 80 parts by weight Polystyrene (molecular weight 20.000) 20
Parts by weight Calcium carbonate 100M parts (CaCO5 average particle diameter 2μs) Masterbatch 5 parts by weight (carbon and resin mixed at a ratio of 20:80) Silane cuffing agent 10 parts by weight (methyltrimethoxysilane) Process in the same way as 1 and make half 10011?
! These were prepared and tested in the same manner as in Example 1, and the results are shown in Table 1.

The results in Table 1 show that even when 10 parts by weight of the silane coupling agent was contained, all items were good.

Example 4 Polystyrene (molecule [300,'000) 80
Part by weight polystyrene (molecular weight 20,000) 2
0 parts by weight Calcium carbonate 100 parts by weight (CaCO3 average particle size 2μ haze) Masterbatch 5 parts by weight (carbon and resin mixed at a ratio of 20:80) Silane coupling agent 1 part by weight (γ-aminobrobiltrie I xysilane) was treated in the same manner as in Example 1 above to produce 100 halves, and these were also tested in the same manner as in Example 1. The results are shown in Table 1.

The results in Table 1 show that all items were good even when different types of silane cuffing agents were used.

Example 5 Polystyrene (molecular weight 300.000) 80 parts by weight Polystyrene (molecular weight 20.000) 2
0 parts by weight Calcium carbonate 100 parts by weight (CaCO3 average particle size 2 μm) Masterbatch 5 parts by weight (carbon and resin mixed at 20880) Titanium coupling agent IM parts by weight Isopropyl!・Lioctanoyl titanate) was treated in the same manner as in Example 1 above to produce 100 halves (solidly manufactured), and these were also tested in the same manner as in Example 1. The results are shown in Table 1.

The results in Table 1 show that even when a titanium-based coupling agent is used, all items are good.

Example 6 Polystyrene (molecular weight 300,000) 80 parts by weight Polystyrene (molecular weight 20,000) 20
Parts by weight Calcium carbonate 100 parts by weight (CaCO3 average particle size 2μ1vI) Masterbatch 5 parts by weight (carbon and resin mixed at a ratio of 20:80) Aluminum coupling agent 1 part by weight (aluminum isopropylate) Process in the same way as 1 and make half 10011M
These were prepared and tested in the same manner as in Example 1, and the results are shown in Table 1.

As a result of Table 1, even if aluminum coupling agent is used,
It can be seen that all items are good.

Comparative Example 1 Polystyrene (molecular fi 300,000) 80
Parts by weight Calcium carbonate 100 parts by weight (CaCO3 average particle size 2 pm) Masterbatch 5 parts by weight (carbon and resin mixed at a ratio of 20:80) were treated in the same manner as in Example 1 above to prepare a half. Table 1 shows the results of testing in the same manner as in Example 1.

As shown in Table 1, in the comparative example, all 100 halves tested had an unreliable appearance, and local precipitation of inorganic filler was observed. This indicates that when injection molding is performed for a short time without adding a cambling agent, inorganic filler is deposited on the surface of the molded product.

Comparative Example 2 Polystyrene (molecular weight 300,000) 80 parts by weight Calcium carbonate 100 parts by weight (CaCO3 average particle size 2 pm) Masterbatch 5 parts by weight (carbon and resin mixed at 20 N 80) Silane cuff bling agent 15 parts by weight (Methyltrimethoxysilane) was treated in the same manner as in Example 1 to prepare a half, and this was also tested in the same manner as in Example 1. The results are shown in Table 1.

As shown in Table 1, in Comparative Example 2, 20 halves were damaged out of 100 halves tested. From this, it can be seen that too much cambling causes a practical problem in terms of strength.

(Hereinafter, the margins of this page) [Effects of the Invention] According to the present invention, since a resin molded body is molded from a composite material of an inorganic filler, a resin, and a coupling agent, the coupling agent improves the wettability of the inorganic filler. This improves the dispersibility in the resin, thereby improving the fluidity of the melt of the composite material and preventing the precipitation of inorganic filler in the molded product. Therefore, even if a mold for injection molding is filled with a melt of the composite material for a short time, precipitation of the inorganic filler can be prevented, and the productivity of molding can be improved.

Furthermore, since the resin used has a high molecular weight, the strength of the molded product can be maintained.

In addition, since a low molecular weight resin is used in combination with a high molecular weight resin, the fluidity of the melt of the composite material can be further improved, making it even more difficult for non-uniform parts to occur in the material of the injection molded product. .

In this way, it is possible to provide a cassette case that can ensure dimensional accuracy and dimensional stability and can meet the recent strict demands for these.

March 28, 1999

Claims (2)

[Claims] (1) Base resin consisting of a thermoplastic resin with a molecular weight of 50,000 to 1,000,000 and a molecular weight of 1,000 to 5
It contains an additive resin consisting of 0,000 parts of resin, an inorganic filler, and a coupling agent, and the ratio of each of these components is 0.5 to 100 parts by weight of the added resin to 100 parts by weight of the base resin.
A resin molded article characterized in that the amount of the inorganic filler is 5 to 200 parts by weight based on 0.1 to 10.0 parts by weight of the coupling agent and 100 parts by weight in total of the base resin and additive resin. (2) Base resin consisting of a thermoplastic resin with a molecular weight of 50,000 to 1,000,000 and a molecular weight of 1,000 to 5
It contains an additive resin consisting of 0,000 parts of resin, an inorganic filler, and a coupling agent, and the ratio of each of these components is 0.5 to 100 parts by weight of the added resin to 100 parts by weight of the base resin.
Parts by weight, 0.1 to 10.0 parts by weight of coupling agent, and 5 to 200 parts by weight of inorganic filler per 100 parts by weight of base resin and additive resin are injection molded. A method for producing a resin molded article.