JPS59172533A - Production of reinforced resin composition - Google Patents

Abstract

PURPOSE:To obtain a reinforced resin composition having excellent properties and appearance of a molding in good workability, by feeding a thermoplastic resin in the form of, for example, granules and fibrous magnesium oxysulfate separately into the feed port of a mixer and melt-blending the both. CONSTITUTION:A thermoplastic resin in the form of pellets or granules, such as crystalline polypropylene, polyethylene, or vinyl chloride resin, and fibrous magnesium oxysulfate are fed separately into the material feed port of a mixer such as a Banbury mixer or a single-or twin-screw extruder, and the both are melt-blended. This makes it possible to prevent separation of the thermoplastic resin from the fibrous magnesium oxysulfate and to obtain the purpose uniform reinforced resin composition. The fibrous magnesium oxysulfate is obtained by dispersing magnesium oxide in an aqueous magnesium sulfate solution and reacting the mixture by heating.

Description

[Detailed description of the invention] The present invention relates to a method for producing a 2-reinforced resin composition.

More specifically, the present invention relates to a method for producing a resin composition containing fibrous magnesium oxysulfate.

Rigidity of thermoplastic resin 1 Mechanical strength, heat resistance.

The technique of blending inorganic substances for the purpose of improving various properties such as molding shrinkage rate 9 and dimensional stability is well known. Inorganic substances used for such purposes include particulate materials such as calcium carbonate, barium sulfate, and magnesium hydroxide, small plate-like or flake materials such as talc and mica, and glass fibers and asbestos. Fibrous substances such as these are well known.

Among these inorganic substances, nine particulate substances do not have a particularly strong reinforcing effect on thermoplastic resins, so thermoplastic resin molded products obtained by blending these particulate substances are suitable for applications that require high performance. In many cases, it cannot be used generally. On the other hand, small plate-like or flake-like materials and fibrous materials exhibit high two-dimensional or -dimensional reinforcing effects, respectively, and are therefore widely used as reinforcing materials for thermoplastic resins. However, these highly effective reinforcing materials also have various drawbacks, which may limit their use depending on the purpose. For example, thermoplastic resins containing small plate-like or flake-like materials generally have a lower level of rigidity in molded products than those containing fibrous materials such as glass fibers, and flow marks occur during molding. It has the disadvantage of being easy to use. On the other hand, when a fibrous substance is blended, the elongation of the molded product is low, silver streaks are likely to occur in the molded product, and the gloss is often poor.

Particularly when glass fiber is used, the disadvantage is that the molded product is susceptible to impact from falling balls. Therefore, when using these conventional reinforcing materials, it is necessary to take into account the drawbacks of each reinforcing material and select a material according to the intended use of the molded product.

Of course, the above-mentioned various drawbacks include the selection of the thermoplastic resin as the base material, the surface treatment of the inorganic material used as the modified reinforcing material, and the addition of appropriate third materials.

Or by methods such as examining molding processing conditions.

Although some improvements can be made, it is difficult to achieve a fully satisfactory improvement.

Therefore, the present inventors have discovered that the above-mentioned drawbacks can be improved by using fibrous magnesium oxysulfate as the inorganic substance, as disclosed in Japanese Patent Application Laid-Open No. 57-109846.

However, fibrous magnesium oxysulfate
Since the bulk specific gravity is extremely small, it is not easy to mix the thermoplastic resin in the form of pellets and granules, which are commonly used in ordinary processing.

Namely, 1. Due to the difference in shape and density of the two, 9. Normally used in the mixing operation of an inorganic substance and a thermoplastic resin, both are mixed in advance using a dry mixer such as a V-type blender or a ribbon mixer, and then melt-mixed. When feeding to a machine (tri-blend method).

Bridging (occlusion) and separation phenomena between thermoplastic resin and fibrous magnesium oxysulfate are likely to occur at the material supply port. For this reason, processability is poor when manufacturing the 1-reinforced resin composition, and it is difficult to obtain a uniform resin composition.
As a result, the physical properties and appearance of the molded product may be poor.

The inventors discovered that thermoplastic resin and fibrous magnesium
The present invention was completed as a result of extensive research into a method for producing a reinforced resin composition that does not have the above-mentioned drawbacks by mixing with oxysulfate.

In other words, the present invention provides a method for producing a reinforced resin composition, which is characterized in that a pelletized or granular thermoplastic resin and fibrous magnesium oxysulfate are separately supplied to a material supply port of a mixer and melt-kneaded. It is about the method.

According to the method of the present invention, a reinforced resin composition that provides a molded article with good physical properties and good appearance can be continuously produced with good processability.

The thermoplastic resin used in the present invention is not particularly limited as long as the processing temperature is 250° C. or lower, and includes crystalline polypropylene, polyethylene, vinyl chloride resin, polystyrene resin, and AB'S resin.

12 nylon, acrylic resin, etc.

In addition to crystalline propylene homopolymers, the crystalline polypropylene mentioned above may include crystalline copolymers of propylene and other α-olefins (especially crystalline nofropylene/ethylene block copolymers, modified or random copolymers). Any crystalline propylene-based polymer, such as polymers such as Among these, the most preferred is a crystalline propylene/ethylene block copolymer, which is excellent in practical performance such as a balance between rigidity and impact resistance. and.

Among these crystalline propylene/ethylene block copolymers, copolymers having an ethylene component content of 2 to 30% by weight and a melt flow index in the range of 0.5 to 401 i'/10 minutes are preferred. A more preferred copolymer has an ethylene component content of 6 to 15% by weight and a melt flow index of 1 to j5. r/, which is in the range of 10 minutes. Furthermore, modified crystalline polypropylene can also be used as the crystalline polypropylene if necessary.

Maleic anhydride is used as modified polypropylene.

Polymerizable vinyl monomers such as acrylic acid and glycidyl methacrylate, or organic silane compounds having unsaturated bonds such as vinylsilane and γ-methacryloxypropyltrimethoxysilane are used together with an organic peroxide to carry out a heating reaction. An example of this is polypropylene obtained by Also for crystalline polypropylene.

It is also possible to use a blend of other known polymers such as polyethylene, polybutadiene, ethylene-propylene rubber, etc. in small amounts.

Moreover, as the above-mentioned polyethylene, one having a density of 0.93 or more is preferably used.

The vinyl chloride resin mentioned above includes not only vinyl chloride homopolymers but also copolymers containing 50% or more of vinyl chloride.

As the polystyrene resin, non-crystalline polymers such as polystyrene, polybutadiene, graft polymers with SBR, and polymer blends are targeted.

As these thermoplastic resins, widely used granulated pellets or granules are used.

The fibrous magnesium oxysulfate used in the present invention is MgSO4-5My0.8H20 or MgSO
It is a synthetic inorganic substance that can be represented by the chemical formula 3-5My(OH)2.3H20. This fibrous magnesium oxysulfate can be produced by, for example, a method in which magnesium oxide or magnesium hydroxide is dissolved in an aqueous solution of magnesium sulfate and reacted by heating, or a method in which magnesium hydroxide is dispersed in a sulfuric acid solution and reacted by heating. can be manufactured.

For specific examples of the manufacturing method of fibrous magnesium oxysulfate and product properties, please refer to JP-A-56-1493.
It is described in detail in the specification of No. 18. 9 The general form of the fibrous magnesium oxysulfate used in the present invention has a true specific gravity of 2.0 to 2.5.
Fiber length) 10-100μ, diameter (fiber diameter) 0.3
~2μ (ratio of fiber length/fiber diameter, 3O-150), and can be described as an extremely bulky fibrous material with an acicular crystal structure having a bulk specific gravity of 0.05 to 0.2.

In the method of the present invention, the blending ratio of the thermoplastic resin in the form of pellets or granules and the fibrous magnesium oxysulfate is generally 30 to 95 parts by weight for the former, particularly 50 to 90 parts by weight, and 70 to 5 parts by weight for the latter. Parts by weight, especially 50~
Values in the range of 10 parts by weight are preferably employed. If the amount of fibrous magnesium oxysulfate is less than 5 parts by weight, the desired reinforcing effect will not be sufficient, while if it is more than 70 parts by weight, the processability of the composition will be poor and good molding will not be achieved. It becomes difficult to obtain goods.

Also, fibrous magnesium oki used in the present invention.

It is also possible to replace a portion of the nosulfate with known filler and/or reinforcing materials. Such filler or reinforcing materials include /71J, such as calcium carbonate;
Talc, mica, barium sulfate, magnenium hydroxide,
Examples include glass fiber and wollastonite. However, it is not appropriate to mix more than the same amount (same weight) of these filler materials and/or reinforcing materials with respect to the fibrous magnesium oxysulfate, and regardless of the amount of substitution, as mentioned above, The fibrous magnesium oxysulfate needs to be blended in an amount of 5 parts by weight or more based on the total composition.

In the method of the present invention, the above-mentioned pelletized or granular thermoplastic resin and fibrous magnesium oxysulfate are mixed in a mixing machine such as a -screw or twin-screw extruder, Banbury mixer, continuous mixer, or roll. It is necessary to separately supply the materials to the material supply ports and melt and knead them.

In the method of this invention, the number of material supply ports may be one or two. In the latter case, melt the thermoplastic resin in advance.

Preferably, fibrous magnesium oxysulfate is added therein.

The feeding device for separately feeding the thermoplastic resin in the form of pellets or granules and the fibrous magnesium oxysulfate to the material feeding port may include a screw feeder, a table feeder, a rotary feeder,
It is preferable to use a continuous metered feeding device such as a vibrating feeder or a belt conveyor set feeder. Still, during melt-kneading.

The effect of the present invention is further improved by performing a degassing operation (venting). This is because the fibrous magnesium oxysulfate is bulky and contains a large amount of air between the fibers, and there is water adhering to the surface.

By the way, the fibrous magnesium oxysulfate used in the present invention undergoes a dehydration reaction as shown in the following formula at high temperatures and releases its molecular water.

(a) Approx. 300℃ (b) Approx. 400℃ M% 04 ・5Mf0 ・5H20→MyS 04
・5MyO+ 5H20 (release) In particular, the first dehydration reaction releases three molecules of water.

Since the reaction initiation temperature is around 250°C, it is necessary to pay attention to the temperature when heat-processing this compound. Therefore, the kneading operation in the present invention is preferably carried out at a temperature not lower than the melting point (or softening point) of the thermoplastic resin used and not higher than 250°C, preferably 190 to 240°C (resin temperature). If kneading is performed above the dehydration start temperature, mixed materials (bellets) will form.

Cavities or pinholes may occur in the sheet, etc.

Undesirable.

As mentioned above, the present invention produces a composition mainly composed of a thermoplastic resin and fibrous magnesium oxysulfate, but this composition further contains a lubricant, a plasticizer,
Addition of surfactants, coupling agents, etc. will further improve processability and various strengths, so it is preferable to add these additives.

As a lubricant, hydrocarbons (such as paraffin wax),
Examples include higher fatty acids, higher fatty acid amides, higher fatty acid metal salts, and esters of higher fatty acids. Examples of plasticizers include phthalic acid esters, aromatic carboxylic acid esters, aliphatic dibasic acid esters, aliphatic ester derivatives,
Commonly known compounds include chlorinated paraffins, phosphoric acid esters, and epoxy fatty acid esters. Also, as a surfactant, it is an anionic type.

Although both cationic and nonionic types can be mentioned, long-chain aliphatic sulfonates and higher fatty acid esters of polyhydric alcohols are representative examples. Typical coupling agents include silane coupling agents, as well as titanate coupling agents, which are well known as processability and flexibility imparting agents.

Among these additives, it is particularly preferable to add higher fatty acid glyceride compounds, which are lubricants belonging to higher fatty acids or esters thereof.

What are the higher fatty acid glyceride compounds mentioned here?

It is an ester (glyceride) obtained from glycerin and higher fatty acids, and can be used in mono- or di-ester.

Any triglyceride may be used. Higher fatty acids include saturated acids such as lauric acid, myristic acid, palmitic acid, and stearic acid, and unsaturated acids such as oleic acid, linoleic acid, and liluic acid.

Linoleic acid (12-hydroxyoleic acid) and 12-
Hydroxy acids such as hydroxystearic acid can also be mentioned. Among these.

Stearic acid monoglyceride, oleic acid monoglyceride, stearic acid diglyceride, ricinoleic acid triglyceride, 12-hydroxystearic acid triglyceride, stearic acid, and the like can be suitably used. Especially when these higher fatty acid glyceride compounds are blended into the composition of the present invention.

The surface condition and impact strength of the resulting molded product are significantly improved.

The amount of these additives added is 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight, per 100 parts by weight of the total of the thermoplastic resin and fibrous magnesium oxysulfate. If the amount added is as small as 0.1 part by weight, the effect of the addition will not be sufficiently manifested. On the other hand, if the amount is more than 5 parts by weight, the rigidity and mechanical strength of the resulting molded product will actually decrease, which is unsuitable.

Furthermore, it is of course possible to add other additives for general plastic material compositions, such as colorants and flame retardants, to the composition of the present invention according to known techniques.

These additives can be added by pre-mixing them into the fibrous magnesium oxysulfate, by pre-mixing them into the thermoplastic resin, or by adding them to the thermoplastic resin and the fibrous magnesium oxysulfate. Any method of integral blending in which it is added during melt-kneading may be used.

The reinforced resin composition produced by the method of the present invention can be prepared using any known molding method such as injection molding, extrusion molding, blow molding, compression molding, vacuum molding, pressure molding, lamination molding, roll processing, stretching processing, stamp processing, etc. It can be made into a molded product.

Examples and comparative examples are shown below.

In addition, in the following text, "part" means "l bone part". The evaluation method is as follows.

Melt flow index (M)・・・ASTM
D-1238 tensile test...A
STM D-638 bending test...AS
TM D-790-66 Izot impact test...
・ASTM D-256-54T rotary hardness
...ASTM D-785 Example 1 Crystalline propylene-ethylene block copolymer pellets (length 2Nn, diameter 4mm) (M work: 92/10 minutes, ethylene content near weight) (hereinafter simply PP ) is processed into fibrous magnesium oxysulfate (fiber length 10-100
μ, fiber diameter 1 μ or less) (hereinafter sometimes simply abbreviated as MOS) are separately fed to the supply port of a 30-kaku twin-screw extruder using a table feeder with a vibration feeder, and melt-kneaded at a nozzle set temperature of 210°C. Then, pellets of a composition consisting of 80 parts of polypropylene and 20 parts of fibrous magnesium oxysulfate were obtained.

Using this pellet, the nozzle temperature was set at 200°C.

Injection molding was performed at a mold temperature of 60° C. to prepare test pieces for measuring various physical properties. Table 1 shows the results of physical property measurements and appearance observations.

Comparative Example 1 After 80 parts of PP and 820 parts of MO used in Example 1 were thoroughly mixed in a V-type blender, this mixture was fed into a twin screw extruder by a screw feeder. The results are shown in Table 1.

Example 2 8100 parts of MO used in Example 1 and 5 parts of stearic acid were thoroughly mixed in a V-type blender. Table 1 shows the results obtained in exactly the same manner as in Example 1 except that 21 parts of the above mixture of MO8 and stearic acid was used instead of 820 parts of MO.

Example 6 Table 1 shows the results obtained in exactly the same manner as in Example 2, except that forced degassing was performed from the vent hole of the twin-screw extruder during melt-kneading.

Example 4 Same as Example except that pp was changed from 80 parts to 70 parts, MOEI was changed from 20 parts to 60 parts, stearic acid was changed from 1 part to 1.5 parts, and the kneading temperature was changed from 210°C to 260°C. The results obtained are shown in Table 2.

Example 5 In Example B, PP was changed to crystalline propylene-ethylene block copolymer pellets (MI: 9/10 minutes, ethylene content near weight %).

Table 2 shows the results obtained in exactly the same manner except that the kneading temperature was changed from 210°C to 230°C.

Example 6 Table 2 shows the results obtained in exactly the same manner as in Example 4 except that PP was changed to PP used in Example 5.

Example 7 Results obtained in exactly the same manner as in Example B except that PP was changed to crystalline propylene-ethylene block copolymer pellets (MI: 1 ft/10 min, ethylene component content -7% by weight) are shown in Table 2.

Example 8 To 100 parts of the PP used in Example 7, 0.5 part of γ-methacryloxypropyltrimethoxysilane and 0.5 part of 1-butylperoxybenzoate were added.

After thoroughly mixing in a Henschel mixer, - using a shaft extruder to melt and heat the mixture at a nozzle setting temperature of 240°C,
Modified propylene-ethylene block copolymer pellets were obtained.

In Example 1, instead of 80 parts of P and P, this PP
Table 2 shows the results obtained in exactly the same manner except that 40 parts of the above-mentioned modified PP were used.

As is clear from the above Examples and Comparative Examples, the composition obtained by the production method of the present invention has better processability than compositions produced by conventionally known methods, and has improved various physical properties of molded products. The appearance is also good.

Patent applicant: Ube Industries Co., Ltd.

Claims (1)

[Claims] 1. A method for producing a reinforced resin composition, which comprises separately supplying a pellet-like or granular thermoplastic resin and a fibrous magnesium oxysulfate to an old feed port of a mixer and melt-kneading them.