JPS5855179B2 - How to strengthen thermoplastic resin - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for strengthening thermoplastic resins.

Thermoplastic resins are used in various fields, but in recent years, they have been used in fields that require so-called strength, such as building materials such as window frames and decking materials, automobiles, other vehicle-related, electrical, and mechanical parts and tools. There is a noticeable increase in the trend toward

However, when thermoplastic resins are used in such fields, the resin alone has a limit in terms of strength, and the range of use has to be considerably limited.

Therefore, it is natural that materials are required to have stronger physical properties.

Therefore, it is desired to expand the range of applications or uses by strengthening the resin in some way, and one method is to strengthen it with fillers.

The present inventors have studied methods for strengthening and modifying various thermoplastic resins using fillers, and have discovered an extremely excellent inorganic compound as a filler for reinforcing thermoplastic resins.

The present inventors have conducted repeated studies to develop this inorganic compound as a filler for thermoplastic resins, and have thus arrived at the present invention. The objective is to improve the mechanical properties or thermal properties of the resin.

The filler will be explained in detail below. The filler falls under the category of inorganic crystalline material called restadite.

The mineral commonly called elestadite is found in natural marble or calcite ore, and has a Ca5
((s+, s, p, C) 04) (CI, F
, OH).

However, elestadite (hereinafter referred to as synthetic elestadite), which was newly developed by the present inventors as a filler, is slightly different from that of natural minerals, and its structural formula is 6CaO.
・3SiCL, ・3C'aS04・nH2O.

The shape of synthetic elestadite is a white hexagonal columnar crystal as shown in the photograph, and the crystal length is about 5 μm.

The present inventors investigated various conditions for synthesizing this synthetic elescudite as a filler for reinforcing synthetic resins, and succeeded in producing a large amount of crystalline material as shown in the photograph.

Raw materials are calcium oxide (Cab), silica stone (Si02),
and 6-positive (Ca SO,i .2H20), and if a mixture (slurry) of these is subjected to a hydrothermal reaction in an autoclave, synthetic elestadite can be obtained.

The reaction temperature is set between 1306C and 230C,
The raw material ratio is S102 is 35 when CaO is 100.
~75, CaSO4.2H20 is adjusted between 100 and 200 (all weight ratios).

The crystal length, aspect ratio, surface area, etc. will vary slightly depending on the settings of the above synthesis conditions, but if the purpose is to be a filler, the crystal length should be 3 to 10 μm, the aspect ratio should be 10 or more, and the surface area should be 1 to 3 m'. /g.

By filling a thermoplastic resin with the synthetic nireshudite obtained in this way and compounding it, the excellent reinforcing effect seen in the examples can be obtained.

The reason why synthetic niresfudite is excellent as a filler for reinforcing synthetic resins is that it has an acicular or columnar shape and a large aspect ratio.

A further feature of synthetic nireshudite is that when it is filled into a resin, it does not suffer from poor processability or poor dispersion, which is common with needle-shaped or columnar fillers.

This is because synthetic niresfudite is not formed as aggregated particles, but
This is because it is obtained in the form of primary particles, and its bulk specific volume is not as large as synthetic acicular fillers such as xonotlite and potassium titanate, but it is extremely small as in crushed natural minerals. This is because it is within an affordable range.

Synthetic niresfudite has a bulk specific volume that is about the same as, for example, vinyl chloride resin powder, so it has extremely good miscibility with resin, and these properties as a powder are very important when used as a filler. It is.

In addition to mechanical properties, the filling effect of synthetic nireshudite also makes an extremely large contribution to thermal properties, such as reducing the coefficient of thermal expansion and increasing the softening temperature.

Therefore, it is effective in imparting dimensional stability during processing, and is particularly useful as a multipurpose filler for irregularly shaped extruded products such as window frames.

The method for filling the thermoplastic resin with synthetic nireshudite may be the same as that for general calcium carbonate, whether it is a roll cross-wire method, an extrusion molding method, or an injection molding method.

In consideration of processability and dispersibility, it is naturally desirable to treat with a fatty acid such as stearic acid or its salts, a titanium coupling agent, or the like.

However, unlike calcium carbonate, synthetic niresfudite binds with a silane coupling agent, so if the purpose is to strengthen it, surface treatment with about 1% of a coupling agent can achieve excellent mechanical effects. You can get it.

The effect of filling a thermoplastic resin with synthetic niresfudite will be described below based on Examples.

Example 1 Vinyl chloride resin (Nippon Zeon 103EP, average degree of polymerization 1
050) 25 to 100 parts by weight of synthetic elestadite shown in the photograph, 3 to 4 parts by weight of a stabilizer (tin-based), and 1.5 to 2 parts by weight of a lubricant were blended into 100 parts by weight, and kneaded with a roll.

Roll temperature: 165°C, rolling time: 5 minutes.

The obtained sheets were stacked and press-molded into a plate shape with a thickness of 3 mm.

Press temperature 170℃, press pressure 100 kg/crr
Dumbbell-shaped and rectangular test pieces were cut from t0 and mechanical properties were measured.

All tests were conducted at 23°C and 50RH%.

The results are shown below as Table 1. As seen in Table 1, the contribution to the bending Young's modulus is large, and the drop in impact strength is relatively small.

Therefore, it is possible to increase the bending Young's modulus and reduce elasticity (that is, impart dimensional stability) without reducing impact resistance.

Example 2 The thermal expansion coefficient and thermal softening temperature (Vicat method) of the sample in Example 1 were measured.

The results are shown in Table 2.

When filled, the coefficient of thermal expansion is halved and the softening temperature increases by about 20'C or more, although this varies depending on the amount filled.

Example 3 Polypropylene resin (Tokuyama Soda PN240) 100
20 parts by weight and 40 parts by weight of synthetic elestadite were added to the parts by weight, and pellets were produced using a -axis extruder.

This was injection molded into each test piece mold, and the mechanical properties were measured in the same manner as in Example 1.

The results are shown in Table 3.

Example 4 For the same sample as in Example 3, the thermal expansion coefficient and thermal softening temperature (Vicat method) were measured according to the method in Example 2.

The results are shown in Table 4. As seen in Tables 3 and 4, excellent filling effects such as reinforcing effects and reduction of thermal expansion coefficient can be seen for polypropylene as well.

[Brief explanation of drawings]

The photograph is a scanning electron micrograph of synthetic elestadite according to the present invention.

Claims (1)

[Claims] 1 5 parts by weight or more of columnar or acicular crystalline synthetic elestadite in thermoplastic resin per 100 parts by weight of resin
A method for strengthening thermoplastic resin characterized by filling up to the weight part.