JPH0711049A - Thermoplastic resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition having excellent impact strength, particularly falling weight impact strength, and high dispersibility by adding a specific amount of columnar or needle calcium carbonate having the lateral length and aspect ratio distributing in prescribed ranges, respectively, to a thermoplastic resin. CONSTITUTION:100 pts.wt. of a thermoplastic resin such as polyvinyl chloride resin are added with 0.5 to 50 pts.wt. of columnar or needle calcium carbonate having 0.5 to 5mum lateral length and 5 to 50 aspect ratio, and in addition, mixed with an organic thermal stabilizer, a lubricant comprising fatty acid ester and polyethylene wax, acrylic reinforcement and processing auxiliary in a supermixer at 120 deg.C to form into a compounded material to give the objective thermoplastic resin composition giving molded products of high impact strength, particularly falling weight impact strength, and improved surface properties on extrusion or injection molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin composition excellent in impact resistance, which is obtained by mixing a thermoplastic resin with calcium carbonate having a specific particle shape.

[0002]

2. Description of the Related Art In order to improve the impact resistance of thermoplastic resins, mixing of various inorganic fillers has been studied so far. For example, in JP-A-56-67365, the combined use of talc and calcium carbonate as an inorganic filler improves the tensile strength and bending strength, reduces the anisotropy, and reduces the impact strength. A thermoplastic resin composition is disclosed.

Further, Japanese Patent Laid-Open No. 1-282421 discloses a technique for improving the flexural modulus of vinyl chloride resin by devising a mixing ratio of mica and calcium carbonate having a limited aspect ratio.

In order to improve various physical properties such as thermal properties, mechanical properties and electrical properties by mixing an inorganic filler with a thermoplastic resin, the shape of the inorganic filler may be fibrous, needle-shaped, or flaky. It is said that the shape is preferable. Further, as the inorganic filler, for example, glass fiber, clay, talc, mica, gypsum fiber and the like are known.

However, when these inorganic fillers are mixed, there is a drawback that the impact strength of the thermoplastic resin, particularly the strength against falling weight impact, is extremely lowered. It is considered that this is because the inorganic filler in the thermoplastic resin is poorly dispersed and aggregates. Further, when these inorganic fillers are mixed, the thermoplastic resin has a drawback that it tends to be oriented when it is molded by extrusion molding, injection molding or the like, and the physical properties are remarkably different in the direction orthogonal to the orientation direction.

By the way, even if calcium carbonate is mixed alone, the effect as an inorganic filler as described above cannot be obtained. For example, since ground calcium carbonate has an indefinite shape and a large particle size, the effect of improving the physical properties cannot be expected, and the impact strength is disadvantageously decreased with an increase in the addition amount.

[0007] Light and colloidal calcium carbonate has improved impact strength, but its effect is small, and since it is fine particles, a large amount of surface treatment agent is required, and plate-out occurs during molding such as extruder and injection molding. It also had a drawback that the surface condition of the product deteriorated.

[0008]

In view of the above-mentioned drawbacks, the present invention provides a thermoplastic resin composition which is excellent in impact strength of thermoplastic resin, particularly in falling weight impact strength.

[0009]

The thermoplastic resin composition of the present invention comprises 100 parts by weight of a thermoplastic resin and 0.5 to 50 parts by weight of calcium carbonate having a specific particle shape.

Here, the specific particle shape means a columnar shape or a needle shape having a lateral length of 0.5 to 5 μm and an aspect ratio of 5 to 50. Here, the aspect ratio means a ratio between the length and the thickness, whichever is larger in the vertical direction or the horizontal direction.

Calcium carbonate includes glass fiber, clay,
Like talc, mica, gypsum fiber, etc., it generally has a needle shape or a spindle shape, but calcium carbonate constituting the thermoplastic resin composition of the present invention is characterized by a small aspect ratio, As a result, the remarkable effect of the present invention is that orientation does not occur even when molding by an extruder or injection molding.

According to the present invention, dispersibility with a thermoplastic resin can be maintained without using a large amount of a surface treatment agent such as general light or colloidal calcium carbonate.

The present invention is constituted by adding calcium carbonate having the above particle shape to a thermoplastic resin. With the thermoplastic resin composition of the present invention, it is possible to obtain a molded article having extremely excellent impact strength without orientation and without plate-out.

The thermoplastic resin to which the present invention can be applied is not particularly limited. For example, when applied to a crystalline thermoplastic resin such as high-, medium- or low-density polyethylene, polypropylene or nylon resin, good impact strength can be obtained.

The present invention is also preferably applied to an amorphous thermoplastic resin because it can obtain a better impact strength by being applied to an amorphous thermoplastic resin.

Examples of the amorphous thermoplastic resin to which the present invention can be applied include polystyrene, polyethylene, polypropylene, AS resin, ABS resin, polyvinyl chloride resin and the like. Further, two or more kinds of these resins may be mixed and applied.

In particular, it has been found that the effect of the present invention becomes extremely large when the calcium carbonate having the particle shape of the present invention is added to the polyvinyl chloride resin. Examples of the polyvinyl chloride resin include polyvinyl chloride resin, polyvinylidene chloride resin, vinyl chloride-vinyl acetate copolymer, vinyl chloride-ethylene copolymer, chlorinated polyvinyl chloride resin and the like, and in the present invention, , These alone or 2
It is also possible to apply a mixture of two or more species.

Further, an impact resistance improver such as MMA resin, MBS resin and chlorinated polyethylene may be mixed.

As the compounding agent, general-purpose polyvinyl chloride additives such as tin-based, Ca / Zn-based, and lead-based heat stabilizers, lubricants and processing aids may be used. If necessary, other fillers can be used together in a small amount.

The particle shape of the calcium carbonate according to the present invention is required to have a lateral length in the range of 0.5 to 5 μ, and more preferably 1 to 4 μ. Also,
The aspect ratio must be in the range of 5 to 50,
More preferably, it is 10 to 20.

When the particle length direction becomes 0.5 μ or less,
The dispersibility is poor and the impact strength does not develop. Further, when the lengthwise direction of the particles is 5 μm or more, the particles become large and impact strength is not exhibited.

When the aspect ratio of the calcium carbonate according to the present invention is 5 or less, the impact strength does not appear like the general-purpose calcium carbonate. When the aspect ratio is 50 or more, the orientation becomes easy, and the physical properties are remarkably different in the direction perpendicular to the orientation direction.

In the present invention, the calcium carbonate of the present invention is added in an amount of 0.5 to 100 parts by weight of the thermoplastic resin.
It is necessary to add it in the range of 50 parts by weight, but more preferably 0.5 to 30 parts by weight. If the amount of calcium carbonate added is 0.5 parts by weight or less, the effect will not be exhibited because it is too small. Also, the amount of calcium carbonate added is 5
If the amount is 0 parts by weight or more, the impact strength will decrease.

The calcium carbonate applied to the present invention can be used after being surface-treated with a silane coupling agent, an organic titanate, a fatty acid, etc., if necessary. In the present invention, the molding method of the thermoplastic resin composition is not particularly limited, and any conventionally known molding method can be adopted. For example, an extrusion molding method, an injection molding method, a calender molding method and the like can be mentioned.

[0025]

EXAMPLES The present invention will be described in more detail with reference to Examples of the present invention. Example 1 The composition shown in Table 1 and the inorganic filler shown in Table 2 were compounded at 120 ° C. using a super mixer. The blended composition thus obtained was subjected to the following evaluations, and the measurement results are shown in Table 3.

1) Charpy impact test (JISK-71
11) 20 mm at a resin temperature of 190 ° C with a 50 mm twin-screw different direction extruder
The A pipe was extruded. The parison was cut open and cooled with water to form a sheet. A test piece was cut out in the extruding direction (MD) and in the transverse direction (TD) and measured at 23 ° C.

2) Drop weight impact test A 20 mmφ pipe with a wall thickness of 3 mm was molded at a resin temperature of 190 ° C. with a 50 mm biaxial extruder, and this pipe was
It was cut to a length of 0 mm and expressed as a 50% crack height of 1 Kg weight at 0 ° C.

3) Plate Out A 30 mm single extruder was used for 2 hr extrusion with a resin temperature of 200 ° C. and an extrusion rate of 5 kg / hr using a 5 × 25 mm slit die. After that, the slit die was disassembled, and it was visually determined whether or not the white matter remained. The judgment method is the following 2
Expressed in rank.・ There is white matter on the whole surface ○ ・ There is no white matter ×

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

[0032]

The composition of the thermoplastic resin composition of the present invention is as described above, and it is possible to obtain a thermoplastic resin molded article having excellent impact resistance, particularly falling weight impact strength. Further, even if the surface treatment agent is not used in a large amount, the dispersibility with the thermoplastic resin is excellent, and a molded product having an excellent surface condition can be obtained without plate-out during molding such as extrusion molding and injection molding. .

Claims (1)

[Claims] 1. A columnar or acicular calcium carbonate having a lateral length of 0.5 to 5 μm and an aspect ratio of 5 to 50,
A thermoplastic resin composition obtained by adding 0.5 to 50 parts by weight to 100 parts by weight of a thermoplastic resin.