JP3378950B2 - High sliding rubber-modified styrenic resin composition - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a rubber-modified styrene resin composition having a high sliding property. Styrene-based polymers are one of the thermoplastic resins that have a wide range of uses, but the biggest drawback of these resins is that they are poor in slidability. The present invention is a resin composition having a high slidability (low friction coefficient, low wear amount) obtained by containing a polyorganosiloxane in a rubber-modified styrene resin composition in which rubber particles within a specific particle size range are dispersed. It is about things. INDUSTRIAL APPLICABILITY According to the present invention, it is possible to replace an expensive engineering plastic resin, improve scratch resistance of a product, and have a great value as an economical resin capable of cost reduction. In addition, the resin composition according to the present invention is suitable for use in the field of light electrical appliances such as home appliances.
It can be widely used as a rotating device for equipment A, a hub material for VTR tape, a shell material for micro floppy disks, foods, containers in the field of sundries, gears for rotating parts, and the like.

[0002]

2. Description of the Related Art Rubber-modified styrene resins are used in a wide range of fields such as daily necessities, miscellaneous goods, and light electric appliances, because they have excellent impact resistance in addition to moldability. In recent years, by incorporating polyorganosiloxane into such a rubber-modified styrene-based resin, a rubber-modified styrene-based resin having excellent abrasion resistance has been obtained. For example, in order to obtain a resin composition having excellent abrasion resistance, JP-A-2-145635 discloses that a polyorganosiloxane having a specific viscosity of 0.5 to 1.5 parts by weight as a silicon content and a specific alcohol. 0.05 with a compound having a hydroxyl group
A rubber-modified styrene-based resin composition having excellent slidability, which is contained by up to 2.0 parts by weight, is disclosed. Further, in JP-A-2-49049, 2.2 to 3.2 parts by weight of polydimethylsiloxane having a specific viscosity (0.8 to 0.5 as a silicon content) is used.
1.2 parts by weight), and 0.1 to 1.5 parts by weight of a high degree of polymerization polydimethylsiloxane having a specific molecular weight (0.04 to 0.6 parts by weight as a silicon content). A rubber-modified styrenic resin composition having excellent properties is disclosed. In Japanese Patent Publication No. 3-68060, a rubber-modified styrenic resin having a specific rubber particle size is used, and a polyorganosiloxane having a specific viscosity is contained as a silicon component in an amount of 0.25 to 1.25 parts by weight, which is abrasion resistance. Of excellent rubber-modified styrenic resin composition is disclosed. These conventional resin compositions have excellent sliding properties and are widely used as substitutes for expensive engineering plastic resins.

[0003]

However, while these resin compositions found in the prior art are excellent in abrasion resistance, they contain a large amount of polyorganosiloxane, which causes a phenomenon of poor appearance in molding. It had a drawback that silver strips, which is one, are easily generated. The occurrence of this silver strip depends on the type of molding machine used, but in general,
It tends to occur in molding machines with strong shearing force. Further, when the content of polyorganosiloxane is high, there has been a problem that the color of the molded product becomes lighter than the original color and it is difficult to adjust the color in the coloring step. By the way, since polyorganosiloxane is expensive, it is not preferable to use a large amount of polyorganosiloxane because the cost is economically increased. Therefore, with a small content of polyorganosiloxane, it has sufficient slidability,
There has been a strong demand for the development of a rubber-modified styrene-based resin having economically high slidability, which does not cause a problem in the appearance of the molded product.

[0004]

Therefore, the present inventors have
As a result of extensive studies to solve such a problem, it was found that the above problems can be solved by a composition comprising a rubber-modified styrene resin having a specific rubber particle diameter and an organic polyorganosiloxane. That is, the present invention is

In the rubber-modified styrenic resin composition in which the rubber-like polymer is dispersed in the form of particles, the weight average particle diameter of the dispersed particles (A) is in the range of 1.5 to 3.5 microns,
(B) In 100 parts by weight of the composition, a polyorganosiloxane having a viscosity of 100 to 30,000 centistokes at 25 ° C. is more than 0.2 as a weight part of silicon,
The present invention relates to a rubber-modified styrenic resin having high slidability achieved by containing an amount of less than 0.25.

The rubber-modified styrenic resin used in the present invention can be produced by a bulk polymerization method, a suspension polymerization method, an emulsion polymerization method or the like in which an aromatic monovinyl monomer is polymerized in the presence of a rubber-like polymer. it can. The rubber-modified polystyrene-based resin having a specific rubber particle diameter as referred to in the present invention can be produced by controlling the state of stirring in the polymerization step, the mixed state at the time of producing rubber particles, and the like.

Examples of the aromatic monovinyl monomer used in the present invention include styrene and o-methylstyrene, p-methylstyrene, m-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, p-tert-butylstyrene and the like. Nuclei alkyl-substituted styrene, α-methylstyrene, α
An α-alkyl-substituted styrene such as -methyl-p-methylstyrene is used. The rubber-like polymer may be polybutadiene, styrene-butadiene copolymer, or the like. As the polybutadiene, both high-cis polybutadiene having a high cis-bond content and low-cis polybutadiene having a low cis-bond content can be used. In order to obtain a rubber-modified polystyrene resin having a particularly high slidability (low friction coefficient, low wear amount), 70% by weight or more of the rubber-like polymer contains cis-1,4 bonds in a proportion of 90 mol% or more. ,
A rubber-modified polystyrene resin using high-cis polybutadiene is preferable.

The rubber-modified polystyrene-based resin produced according to the present invention has a rubber-like polymer dispersed in particles,
It is necessary that the weight average particle diameter is in the range of 1.5 to 3.5 microns, preferably 1.5 to 3.0 microns. When the weight average particle diameter is smaller than 1.5 μm, not only the impact strength is lowered but also the cause is unknown, but the friction coefficient is increased, which is not preferable. On the other hand, 3.
When it is larger than 5 μm, although it is effective in reducing the friction coefficient, the elastic modulus is lowered and an excellent resin cannot be obtained.

The term "weight average particle size" as used in the present invention means a Coulter counter (Coulter Multisizer II) equipped with an aperture tube having a diameter of 30 microns.
Type). As the method, 2 to 3 pellets of the rubber-modified styrenic resin are dissolved with a mixed solvent of methyl ethyl ketone / acetone to dissolve only the polystyrene portion forming the matrix, and then the undissolved rubber particle portion in a centrifuge is used. It is separated and then dispersed in a dimethylformamide electrolyte solution at an appropriate concentration for measurement.

The polyorganosiloxane used in the present invention is represented by the following general formula (1). [Si (R) ₃ ] -O- [Si (R ') (R ") O] _m- [Si (R) ₃ ] General formula (1) (wherein R in the formula is an alkyl group, a haloalkyl group, An aryl group or a haloaryl group, and R ′ and R ″ represent a phenyl group or an alkyl group of C _{1 to} C ₆ ,
It is assumed that m is a natural number representing a polysiloxane unit that should maintain the liquid state of this polyorganosiloxane. )

Typical of the polyorganosiloxanes used in the present invention are various types such as polydimethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, trichloropropylmethylsiloxane, trichlorophenylmethylsiloxane or methylphenyldimethylsiloxane. Examples thereof include copolymers. Among these, polydimethylsiloxane is particularly preferable from the viewpoint of the effect of reducing the friction coefficient and the amount of wear. These may be used alone or in combination of two or more.
A viscosity at 5 ° C of 100 to 30,000 centistokes, preferably 500 to 15,000 centistokes is suitable. When the viscosity is 100 centistokes or less, it becomes difficult to obtain the effect of reducing the friction coefficient and the wear amount, which are the objects of the present invention, and conversely, 300
When it is greater than 00 centistokes, the amount of wear increases, which is not preferable. The content of the polyorganosiloxane is 1 of the rubber-modified styrene resin.
The content of silicon is more than 0.2 and less than 0.25 with respect to 00 parts by weight. This content is 0.2
If the amount is less than the weight part, the effect of substantially high slidability cannot be expected, and if the amount is more than 0.25 part by weight, silver strips are liable to appear in the molded product, and the appearance, colorability and dimensional stability of the molded product are hindered. Both of them are not preferable because they occur.

The method for producing the resin composition of the present invention is not particularly limited, and for example, polyorganosiloxane may be added to styrene monomer to carry out polymerization, or rubber-modified polystyrene and polyorganosiloxane may be used. Melt mixing may be performed using an extruder or the like. further,
A molded product may be obtained by producing master pellets having a high polyorganosiloxane concentration from polyorganosiloxane and polystyrene and mixing the master pellets and rubber-modified polystyrene. In addition, the resin composition of the present invention is a dye / pigment, a lubricant, a filling reinforcing agent, a release agent, a plasticizer, an antistatic agent,
Additives such as antioxidants and flame retardants can be added as necessary.

[0013]

The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto.

The physical properties and slidability were evaluated according to the following methods. (1). Form a disk with a friction coefficient of 101.6 mm outer diameter and 3.2 mm thickness,
Using a friction measuring device, a steel ball having a diameter of 3 mm was brought into contact with the disc, and the measurement was performed under the conditions of a load of 500 g and a moving speed of 1.0 mm / s. (2). Abrasion amount The surface of a steel rod having a diameter of 12 mm was applied to the surface of the above disc, and the measurement was performed under a load of 2 kg, a rotation speed of 25 cm / s, and an abrasion time of 60 minutes. (3). Rigidity (flexural modulus) It was determined according to JIS K7203. (4). IZOD impact strength It was determined according to JIS K 7110 (with notch). (5). Appearance Square 160x160mm, 3mm thick flat plate is molded,
The presence or absence of visual defects such as silver strips and burns was visually evaluated.

Example 1 In the polymerization apparatus, one 10-liter complete mixing tank reactor (first reactor), three 18-liter piston flow type reactors (second to fourth reactors), and A device was used in which two volatilization devices were connected in series and combined. 80 parts by weight of styrene monomer, 20 parts by weight of ethylbenzene, and 70% by weight or more of the rubbery polymer have 90% cis-1,4 bond.
A mixed solution with 5 parts by weight of high-cis polybutadiene rubber, which is contained at a ratio of mol% or more, is used as a raw material, and is continuously supplied to the polymerization device from the first reactor at 8 liters / hour, and 122 °
Polymerization was carried out at a temperature of C. Further, the rotation speed of stirring in the second reactor was set to 110 rpm, and the weight average particle diameter of the rubber-like component was adjusted. The polymerization temperature in the second to fourth reactors is 130 ° C to 16 ° C along the flow direction of the polymerization liquid.
The temperature rise was adjusted to 5 ° C. After removing the volatile components from the polymer with a devolatilizer, a rubber-modified polystyrene resin containing 6.5 wt% of a rubber component in the form of pellets was obtained. Next, 100 parts by weight of the rubber-modified polystyrene resin was added to polydimethylsiloxane (viscosity 100
0 cst. / 25 ° C, Toray Dow Corning Silicone Co., Ltd., SH-200 oil) was added so that the silicon content was 0.23 parts by weight, and the mixture was kneaded with an extruder to obtain the resin composition. Got This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Example 2 The stirring rotation speed in the second reactor in Example 1 was 85 rpm.
As the above, the resin composition was prepared in the same manner as in Example 1 except that the weight average particle diameter of the rubber component was adjusted.
This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Example 3 Stirring speed 128 rp in the second reactor in Example 1
As m, the resin composition was prepared in the same manner as in Example 1 except that the weight average particle diameter of the rubber-like component was adjusted.
This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Example 4 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was mixed with polydimethylsiloxane (viscosity 500
cst. / 25 ° C, Toray Dow Corning Silicone Co., Ltd., SH-200 oil) was added so that the silicon content was 0.23 parts by weight, and the mixture was kneaded with an extruder to obtain the resin composition. Got This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Example 5 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was mixed with polydimethylsiloxane (viscosity 150
00cst. / 25 ° C, Toray Dow Corning Silicone Co., Ltd., SH-200 oil) was added so that the silicon content was 0.23 parts by weight, and the mixture was kneaded with an extruder to obtain the resin composition. Got This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Example 6 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was added to polydimethylsiloxane (viscosity 100
0 cst. / 25 ° C, Toray Dow Corning Silicone Co., Ltd., SH-200 oil) was added so that the silicon content was 0.245 parts by weight, and the mixture was kneaded with an extruder to obtain the resin composition. Got This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Example 7 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was added to polydimethylsiloxane (viscosity 100
0 cst. / 25 ° C, Toray Dow Corning Silicone Co., Ltd., SH-200 oil) was added so that the silicon content was 0.205 parts by weight, and the mixture was kneaded with an extruder to obtain the resin composition. Got This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Example 8 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was added to a polyalkyl-modified siloxane (viscosity 1
200 cst. / 25 ° C, Toray Dow Corning
The silicon content of SH-203 oil manufactured by Silicone Co., Ltd. was added so as to be 0.23 parts by weight, and kneaded with an extruder to obtain the resin composition. This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Example 9 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was mixed with polymethylphenylsiloxane (viscosity 120 cst./25°C, Toray Dow Corning.
The silicon content of SH-550 oil manufactured by Silicone Co., Ltd. was added so as to be 0.23 parts by weight, and the mixture was kneaded with an extruder to obtain the resin composition. This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Example 10 Polydimethylsiloxane (viscosity 1000 cst./25°C, manufactured by Toray Dow Corning Silicone Co., Ltd., SH-200 oil) was added to the mixed solution of the raw materials in Example 1. Finally, the silicon content of the pelletized polydimethylsiloxane was adjusted to be 0.23 parts by weight to obtain the resin composition. This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Example 11 3 of the rubber-like polymer in the mixed solution of the raw materials in Example 1
The resin composition was prepared in the same manner as in Example 1 except that 5 parts by weight of low cis polybutadiene rubber containing 0% by weight or less of cis-1,4 bonds in a proportion of 90 mol% or more was adjusted. This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Example 12 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 11 was added with polydimethylsiloxane (viscosity 50
0 cst. / 25 ° C, Toray Dow Corning Silicone Co., Ltd., SH-200 oil) was added so that the silicon content was 0.23 parts by weight, and the mixture was kneaded with an extruder to obtain the resin composition. Got This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Example 13 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 11 was mixed with polydimethylsiloxane (viscosity 10
00cst. / 25 ° C, Toray Dow Corning Silicone Co., Ltd., SH-200 oil) was added so that the silicon content was 0.205 parts by weight, and the mixture was kneaded with an extruder to obtain the resin composition. Got This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Comparative Example 1 Agitation rotation speed of 70 rpm in the second reactor in Example 1
As the above, a resin composition was prepared in the same manner as in Example 1 except that the weight average particle diameter of the rubber-like component was adjusted. This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Comparative Example 2 Stirring speed 150 rp in the second reactor in Example 1
As m, a resin composition was prepared in the same manner as in Example 1 except that the weight average particle diameter of the rubber-like component was adjusted. This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Comparative Example 3 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was mixed with polydimethylsiloxane (viscosity 10 c).
st. / 25 ° C, Toray Dow Corning Silicone Co., Ltd., SH-200 oil) was added so that the silicon content was 0.23 parts by weight, and the mixture was kneaded with an extruder to obtain the resin composition. Got This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Comparative Example 4 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was mixed with polydimethylsiloxane (viscosity 600).
00cst. / 25 ° C, Toray Dow Corning Silicone Co., Ltd., SH-200 oil) was added so that the silicon content was 0.23 parts by weight, and the mixture was kneaded with an extruder to obtain the resin composition. Got This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Comparative Example 5 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was added to polydimethylsiloxane (viscosity 100
0 cst. / 25 ° C, Toray Dow Corning Silicone Co., Ltd., SH-200 oil) was added so that the silicon content was 0.095 parts by weight, and the mixture was kneaded with an extruder to obtain the resin composition. Got This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Comparative Example 6 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was mixed with polydimethylsiloxane (viscosity 100
0 cst. / 25 ° C, Toray Dow Corning Silicone Co., Ltd., SH-200 oil) was added so that the silicon content was 0.19 parts by weight, and the mixture was kneaded with an extruder to obtain the resin composition. Got This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Comparative Example 7 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was mixed with polydimethylsiloxane (viscosity 100
0 cst. / 25 ° C, Toray Dow Corning Silicone Co., Ltd., SH-200 oil) was added so that the silicon content was 0.265 parts by weight, and the mixture was kneaded with an extruder to obtain the resin composition. Got This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

Comparative Example 8 100 parts by weight of a rubber-modified polystyrene resin obtained in the same manner as in Example 1 was mixed with polydimethylsiloxane (viscosity 100
0 cst. / 25 ° C, Toray Dow Corning Silicone Co., Ltd., SH-200 oil) was added so that the silicon content was 0.36 parts by weight, and the mixture was kneaded with an extruder to obtain the resin composition. Got This resin composition was injection molded, and the physical properties and slidability of the molded product were measured. The results are shown in Table 1.

[0036]

[Table 1]

[0037]

The slidable rubber-modified styrene resin composition of the present invention is excellent in slidability, rigidity and impact resistance and has good molding stability. It is used for rotating OA equipment in the field, hub material for VTR tape, and shell material for micro floppy disk.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-2-245051 (JP, A) JP-A-4-185662 (JP, A) JP-A-62-119250 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C08L 51/04

Claims (2)

(57) [Claims] 1. A rubber-modified styrenic resin composition in which a rubber-like polymer is dispersed in a particle form, wherein the (A) dispersed particles have a weight average particle diameter in the range of 1.5 to 3.5 μm. B) 100 parts by weight of the composition contains polyorganosiloxane having a viscosity of 100 to 30,000 centistokes at 25 ° C. in an amount of more than 0.2 and less than 0.25 as a weight part of silicon. A high-sliding rubber-modified styrene resin composition containing 2. The high-sliding rubber according to claim 1, wherein 70% by weight or more of the rubber-like polymer is high cis polybutadiene containing cis-1,4 bonds in a proportion of 90 mol% or more. Modified styrene resin composition.