JP2665603B2 - Method for producing modified polystyrene resin and modified polystyrene resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polystyrene resin modified by grafting polysiloxane and a composition thereof.

[Conventional technology]

Polystyrene resin is hard and has excellent high frequency electrical insulation.
Strong against acids and alkalis, softens from around 90 ° C, 13
Injection molding is easy because it becomes a viscous liquid at around 0 ° C. On the other hand, since the slidability such as the lubricity of the surface of the molded product is insufficient, there is a problem in mold releasability, wear resistance and lubricity during molding.

Conventionally, the aforementioned drawbacks of polystyrene resins have been improved by the following methods.

1) Spraying of a silicone oil such as polydimethylsiloxane onto a mold by spraying 2) Blending of a silicone oil such as polydimethylsiloxane 3) Coexistence of styrene and an olefin compound having a polydimethylsiloxane chain Polymerization 4) Blend of a copolymer of styrene and an olefin compound having a polydimethylsiloxane chain and a styrene resin having no other polysiloxane chain as a constitutional unit 5) Block copolymer having a polystyrene unit and a polysiloxane unit 6 ) Blend of block copolymer having polystyrene unit and polysiloxane unit and styrene resin not having other polysiloxane chain as a constitutional unit 7) Graft copolymerization of styrene monomer to polysiloxane chain 8) Polysiloxane chain Styrene mono A blend of a copolymer grafted with a mer and a styrene resin having no other polysiloxane chain as a constitutional unit [Problems to be Solved by the Invention] In the prior art, a method of spraying silicone oil onto a mold is Oil sprayed as a release agent remains on the surface of the product, and it is inefficient because it is necessary to spray the release agent frequently on the molding die, and it has improved slidability. Is useless for.

The polystyrene resin improved by blending silicone oil generally has poor compatibility with the resin, so the silicone oil is easy to separate at the time of molding or kneading, easily bleeds out, does not mix uniformly, It causes problems such as damage to storage, easy dust accumulation, and deterioration of physical properties.

A copolymer of styrene and an olefin compound having a polydimethylsiloxane chain is available from Yuhsuke Kawakami, RANMurt.
Thesis by hy and Yuya Yamashita (Die Makromolekul
It can be synthesized by radical or anionic copolymerization, including the method described in are Chemie Vol. 185, page 9 (1984)). Insufficient, and a large amount of homopolystyrene is produced as a by-product, which is difficult to remove, and industrially difficult to produce. Therefore, it is also difficult to blend this type of copolymer with other resins.

Methods for synthesizing block copolymers having polystyrene and polysiloxane units are described in JCSaan, DJ.
A paper by Gardon and S. Lindsay (Macromolecules, Vol. 3, page 1 (1970)), A. Marsiat and V. Gallot (Die Makromolekulare Chemie, Vol. 176, 1641 (1975)), JGZillox, JEL Roovers and SB.
Paper by ywater (Macromoleules, Vol. 8, p. 573 (19
75)) etc. and basic monofunctional initiators such as butyllithium, DSBrown, KUFulcher and
RE Wetton's paper (Journal of Polymer Science P
olymer Letter Eddition Volume 8 Page 659 (1970),
Paper by JW Dean (Journal of Polymer Science Pol
ymer Letter Eddition Volume 8 Page 677 (1970)), D.
Paper by J. Legrant (Journal of Polymer Science, Vol. 8, p. 195 (1970)), paper by HG Kim (Macrom
oleules Vol. 5, p. 594 (1972), C. Price, AGWar
Papers by Son and MT Chov (Polymer Volume 13 page 333 (1972)), Papers by FR Jones (Eurpean Polymer
A method using a bifunctional initiator such as sodium naphthalene or lithium naphthalene as described in Journal Vol. 10, p. 249 (1974), etc., P. Bajaj, SK Varshne.
Papers by y and A. Misra (Journal of Polymer Scien
ce Polymer Chemistry Eddition Volume 18 Pages 295 (198
(0)) using lithium biphenyl as an initiator, anionic polymerization of styrene followed by polymerization of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, etc. In addition to the above, it has the drawback of requiring a long reaction time, and since it is difficult to maintain proper reaction conditions, it is difficult to adjust the molecular weight of each polystyrene unit and polysiloxane unit, and to adjust the molecular weight of the final product.
The synthesizable polymer species are limited and it is difficult to obtain products of the intended composition, and thus it is also difficult to blend copolymers of this type with other resins. In addition, this type of block copolymer is described by A. Skoulios (Paper Macromolecules
It can also be obtained by condensation reaction between polystyrene whose both ends are modified with silanol and polysiloxane having a chlorinated functional group at both ends as described in Volume 4, page 268 (1971)). However, this method produces a different number of block moieties, and it is difficult to control the molecular weight of each polystyrene unit and polysiloxane unit and the molecular weight of the final product, and the types of polymers that can be synthesized are limited. Is difficult to obtain, and thus it is also difficult to blend this type of copolymer with other resins.

Graft copolymer of styrene monomer to polysiloxane chain has the possibility that this copolymer itself can be a material with good moldability, abrasion resistance and lubricity during molding. The traditional method of synthesis is by P. Bajaj, D.
Paper by C. Gupta and K. Varshung (Polymer Enginee
ing and Science, Volume 23, page 825 (1983) and JA Barr.
A paper by ie and K. Munday (Journal of Membrance S
cience Vol. 13, p. 175 (1983)), styrene is converted into radicals or ⁶⁰ Co from the vinyl group of polydimethylsiloxane-polymethylvinylsiloxane block copolymer or methylvinylsiloxane-dimethylsiloxane copolymer. It can be obtained by graft copolymerization that polymerizes by irradiation, but this also involves cross-linking reaction, so it is difficult to maintain appropriate reaction conditions, so it is necessary to adjust the molecular weight of each polystyrene unit and polysiloxane unit, Since it is difficult to control the molecular weight of the product, it is difficult to obtain a product having the intended composition, and the resulting graft copolymer has a molecular structure in which styrene is graft-polymerized onto the polysiloxane chain, so other polysiloxane chains When blended with a styrene resin that does not have a structural unit, compatibility may cause problems. There are disadvantages such as, releasability at the time of the final product resin molding, abrasion resistance, the expected effect is not obtained for lubricity and the like.

[Means for Solving the Problems]

It can be expected that the graft copolymer of polysiloxane to polystyrene chain can be obtained by graft-copolymerizing the polysiloxane chain to polystyrene resin by chemical treatment or the like. There is no report that a copolymer was obtained. However, when other polysiloxane chains of this type of graft copolymer are blended with a styrene resin that does not have a structural unit, the compatibility is good, and in particular, the addition of a trace amount selectively modifies only the resin surface. I can expect to be able to do it.

Therefore, if polysiloxane of specific molecular weight and molecular composition can be combined with polysiloxane of specific molecular weight and molecular composition without breaking each molecular chain, releasability, abrasion resistance and lubricity at the time of molding It should be possible to produce a polystyrene-based resin having excellent surface lubricity and improved wear resistance, which does not require a mold release agent during molding.

The present inventors have achieved the present invention as a result of earnestly studying modification of polystyrene-based resin, paying attention to the problem of surface characteristics of polystyrene-based resin as described above. That is, the present invention provides (1) a modified polystyrene resin characterized by comprising reacting a reactive polysiloxane having an amino group at one end with a styrene copolymer containing a maleic anhydride unit. Production method.

(2) The modified polystyrene according to item 1, wherein the styrene-based copolymer containing a maleic anhydride unit is a styrene-based copolymer having a maleic anhydride unit content of 0.01 to 20% by weight. Method for producing a base resin.

(3) The modified polystyrenic resin according to item 1 or 2, wherein the reactive polysiloxane having an amino group at one end is a reactive polysiloxane having a weight average molecular weight of 100,000 or less. Production method.

(4) When reacting a reactive polysiloxane having an amino group at one end with a styrene-based copolymer containing a maleic anhydride unit, a styrene-based copolymer containing a maleic anhydride unit of the reactive polysiloxane. The method for producing a modified polystyrene resin according to any one of items 1 to 3, wherein the ratio to the polymer is 0.05 to 70% by weight.

(5) A method for producing a modified polystyrene resin composition, which comprises mixing the modified polystyrene resin according to any one of items 1 to 4 with a styrene polymer.

(6) A modified polystyrene resin composition characterized in that a styrene polymer is blended with a styrene copolymer containing a maleic anhydride unit, and then a reactive polysiloxane having an amino group at one end is reacted. Method of manufacturing things.

(7) The modified polystyrene according to item 6, wherein the styrene-based copolymer containing a maleic anhydride unit is a styrene-based copolymer having a maleic anhydride unit content of 0.01 to 20% by weight. Method for producing a resin composition.

(8) The modified polystyrene resin composition according to item 6 or 7, wherein the reactive polysiloxane having an amino group at one end is a reactive polysiloxane having a weight average molecular weight of 100000 or less. Method of manufacturing things.

(9) The styrene-based polymer is one polymer selected from the group consisting of styrene polymers and styrene copolymers, or a mixture of two or more polymers, 5th to 8th features. A method for producing the modified polystyrene resin composition according to any one of 1.

It is.

It has previously been pointed out that polystyrene-based resin obtained by graft-copolymerizing polystyrene with polystyrene is effective for improving the wear resistance and lubricity of the surface and for improving the releasability during molding. . Nevertheless, these polystyrene-based resins have problems in the production of modifiers for polystyrene-based resins and in the modification of resins, and a technical method based on the unified principle has not been established yet. In particular, polystyrene resin was poor in reactivity and it was very difficult to carry out graft copolymerization. The advantages of the present invention are obtained by a method of reacting a reactive polysiloxane having an amino group at one end with a styrenic copolymer containing a maleic anhydride unit, which has a clearly controlled structure. The quality polystyrene resin solves this unsolved problem all at once, and makes it possible to improve and modify the releasability, abrasion resistance, and lubricity of the polystyrene resin during molding.

Polystyrene resin is low-priced, hard, has excellent water resistance, high-frequency electrical insulation, is not affected by acids and alkalis, and is easy to injection mold, so its application is extremely wide.
In carrying out the above-mentioned modifications and improvements to the polystyrene resin, it is necessary to be able to flexibly meet the variety of requirements.

The modified polystyrene resin of the present invention is obtained by reacting a styrene copolymer containing a maleic anhydride unit with a reactive polysiloxane having an amino group at one end. Both the polystyrene-based copolymer containing a maleic anhydride unit as a raw material and the reactive polysiloxane having an amino group at one end can be changed depending on the purpose at any time such as molecular composition, molecular weight, and molecular structure. Therefore, the modified polystyrene resin of the present invention is excellent in versatility, flexibility and easiness in designing a molecular composition, a molecular weight and a molecular structure according to requirements.

The styrene-based copolymer containing a maleic anhydride unit in the present invention is preferably a polystyrene-based copolymer containing 0.01 to 20% by weight of a maleic anhydride unit,
A particularly preferred range of the maleic anhydride unit content is 0.05.
~ 15% by weight. Content of maleic anhydride unit is 0.01
If it is less than 10% by weight, the reaction between the maleic anhydride unit and the reactive polysiloxane having an amino group on the piece of chopsticks becomes difficult,
It is difficult to form the graft copolymer. On the other hand, if it exceeds 10% by weight, unreacted acid anhydride groups will dissipate the modification function of the polysiloxane chain, reducing the sliding properties such as lubricity of the surface of the molded product, and the releasability and abrasion resistance during molding And lubricity may be adversely affected.

Further, the styrene-based copolymer is obtained by adding a mixture of a styrene monomer and a maleic anhydride monomer in a suitable molar ratio, a radical generator and a chain transfer agent to a ketone-based solvent such as acetone or methyl isobutyl ketone. It can be obtained by thermally polymerizing under a temperature condition of 75 to 140 ° C., and then precipitating the resulting polymer with a poor solvent such as petroleum benzine or methanol. Other monomers such as acrylonitrile, butadiene, methylmethacrylate, acrylamide, maleimide,
There is no problem in copolymerizing by adding maleic acid dialkyl ester or the like, and various additives such as heat stabilizers, ultraviolet absorbers, lubricants, colorants or antistatic agents, or various fillers such as You may mix talc, glass fiber, etc. Therefore, a commercially available maleic anhydride-containing polystyrene resin can be used without any problem.

The reactive polysiloxane having an amino group at one end in the present invention has an amino group-containing substituent only at one end and has a weight average molecular weight of 100,000 or less, preferably 50,000 or less. The lower limit of the weight average molecular weight of the polysiloxane is
1000 is desirable. When the weight average molecular weight is 100,000 or more, the reactivity with the polystyrene-based copolymer containing 0.01 to 20% by weight of maleic anhydride unit may be lowered.

When a reactive polysiloxane having amino groups at both ends is used, the maleic anhydride unit content is 0.01 to 20% by weight.
In the reaction with the polystyrene-based copolymer contained therein, remarkable three-dimensionalization occurs, the melting temperature rises, or the dispersibility decreases, which adversely affects the moldability and the final product.

The weight average molecular weight can be measured by gel permeation chromatography. The reactive polysiloxane may be produced by any method as long as it has an amino group-containing substituent at one end, but a living polymerized polysiloxane is used as a skeleton from the viewpoint of easy control of polymerization degree and molecular weight distribution. Is particularly preferable. Such a reactive polysiloxane is obtained by, for example, living polymerization of hexamethylcyclotrisiloxane in the presence of a lithium catalyst using trimethylsilanol or silanoldimethylsiloxane oligomers having both ends as an initiator, and then reacting with dimethylchlorosilane to produce Si at one end. By introducing a --H bond and utilizing a hydrosilylation reaction which is commonly used in silicon chemistry, one end can be converted to an amino group-containing substituent. When reacting a reactive polysiloxane having an amino group at one end with a styrene copolymer containing a maleic anhydride unit, a styrene copolymer containing a maleic anhydride unit of the reactive polysiloxane. The addition ratio is preferably 0.05 to 70% by weight, 0.1 to 5
It is particularly preferably 0% by weight. If the amount is less than 0.05% by weight, the surface lubricity and wear resistance of the final product will be insufficient, resulting in 70% by weight.
In the case of the above, the graft copolymer becomes grease-like, and the compatibility may be lowered, and bleeding may occur, and physical properties may be deteriorated, which may result in undesirable effects. The modified polystyrene resin of the present invention can be produced by any of various methods such as a known solution method and melting method.

When the modified polystyrene resin is produced by a solution method among these, the maleic anhydride-containing polystyrene resin and the reactive polysiloxane having an amino group at one end are stirred in a common solvent, The target product can be obtained only by removing the solvent, and if necessary, the target product is made into a fine powder and various additives such as a heat stabilizer,
It is possible to add UV absorbers, lubricants, colorants or antistatic agents, or various fillers, such as talc, glass fibers and the like. As the solvent used at this time,
For example, linear or cyclic ethers such as diisopropyl ether, di-n-propyl ether, dioxane, tetrahydrofuran, acetone, methyl ethyl ketone,
Aliphatic or aromatic ketones such as methyl isobutyl ketone, acetophenone and cyclohexanone, esters such as ethyl acetate, isobutyl acetate and acetic acid-n-butyl, aromatic hydrocarbons such as toluene and xylene. . Even if it is a solvent other than those exemplified here, it is economical or economical as long as it is a common solvent for the styrene copolymer containing a maleic anhydride unit and the reactive polysiloxane having an amino group at one end. As long as there is no problem from the viewpoint of safety and hygiene, any one can be used and there is no problem in using it as a mixed solvent of two or more kinds.

Although the reaction temperature may be room temperature, there is no problem in raising the temperature to a temperature at which the solvent boils.

When the modified polystyrene resin of the present invention is produced by a melting method, the above-mentioned maleic anhydride unit is contained by using a melt kneader used in the field of general synthetic resins, for example, an extruder. It can be obtained by reacting a styrene-based copolymer and a reactive polysiloxane having an amino group at one end while melt-kneading. At this time, the kneading temperature is preferably not lower than the melting point of the styrene-based copolymer containing the maleic anhydride unit used and not higher than 250 ° C. If the temperature exceeds 250 ° C, the stability of the reactive polysiloxane, which is one of the raw materials, may be impaired, and the stability of the other styrene-based copolymer containing a maleic anhydride unit may be impaired. At this time, various additives such as heat stabilizers, ultraviolet absorbers, lubricants, colorants or antistatic agents, and various fillers such as talc and glass fibers can be optionally added.

Next, the modified polystyrene resin composition of the present invention can be produced by any of the following two methods. The first method is to produce a modified polystyrene resin as a master batch by the above-mentioned method, and to produce a styrene polymer by a melting method under the same conditions as when producing the modified polystyrene resin. The above-mentioned various additives can be added at the time of blending.
The second method is a method of simultaneously producing a modified polystyrene resin and blending with a styrene polymer, which comprises a styrene copolymer containing a maleic anhydride unit and a reactive polymer having an amino group at one end. Siloxane and styrenic polymer are mixed / melted / reacted, for example, by the same melting method as described above, or it is disadvantageous in terms of cost, but in some cases, they are dissolved in a common solvent and then heated. The modified polystyrene resin composition of the present invention can also be obtained by a method of reacting and then removing the solvent if necessary. At this time, it is the same as in the first method that a large amount of additives can be added.

As the styrene-based polymer which is a constituent unit of the composition, polystyrene, high-impact polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-styrene-acryl which are generally commercially available. Rubber copolymer, acrylonitrile-styrene-EPDM (ethylene-propylene-diene terpolymer) copolymer,
Acrylonitrile-chlorinated polyethylene-styrene copolymer, methyl methacrylate-butadiene-styrene copolymer, styrene-butanediene-ethylene-styrene block copolymer and the like can be exemplified, but basically styrene as a polymerization unit. There is no particular restriction as long as it is a polymer containing, but a polymer having a small content of a highly reactive group such as an acid anhydride group such as a maleic anhydride group or a carboxyl group in a polymerized unit is preferable. preferable.
Further, two or more kinds of styrene-based polymers may be mixed and used without any problem.

〔Example〕

Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 3 Styrene-maleic anhydride copolymer (maleic anhydride content 8% by weight, melt index 2.2 measured according to ASTM-D128-73) and powdery polystyrene resin (JIS
Melt flow rate measured according to K 7210 is 21.6)
And a polysiloxane having a weight average molecular weight of 5000 measured by gel permeation chromatography of the following structural formula at the composition ratio shown in Table-1, and then the cylinder temperature was adjusted.
The mixture was extruded at 200 to 220 ° C. with an extruder. The obtained composition was molded by an injection molding machine with a cylinder temperature of 180 to 200 ° C. to give a test piece, and the physical properties were measured using this test piece. Table 1 shows the results.

Example 4 67 parts by weight of the same styrene-maleic anhydride copolymer used in Examples 1 to 3 was dissolved in 700 parts by weight of tetrahydrofuran, and 33 parts by weight of the same polysiloxane as those in Examples 1 to 3 was added. The mixture was reacted with stirring for a period of time, and then tetrahydrofuran was removed by a rotary evaporator. The residual solid was pulverized and further dried in vacuum to obtain a graft product.

9 parts by weight of this graft product and 91 parts by weight of the same polystyrene resin used in Examples 1 to 3 were used at a cylinder temperature of 20.
The mixture was kneaded and extruded with an extruder at 0 to 220 ° C. The physical properties of the obtained composition were measured in the same manner as in Example 1. Table 1 shows the results.

Example 5 Powdered styrene-maleic anhydride copolymer (maleic anhydride content 1% by weight, melt index 2.5 measured according to ASTM-D128-73) used in Examples 1-3. 3 parts by weight of the same polysiloxane as in Example 1 were mixed and then kneaded and extruded by an extruder having a cylinder temperature of 200 to 220 ° C. The physical properties of the obtained polymer were measured in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 1 The polystyrene resin used in Example 1 was used as a comparison target, and its physical properties were measured in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 2 5 parts by weight of a reactive polysiloxane having a weight average molecular weight of 5000 and having amino groups at both ends and having the following structural formula, and Example 1
Using 10 parts by weight of the same styrene-maleic anhydride copolymer and 85 parts by weight of powder polystyrene used in Examples 1 to 3, kneading and extrusion were attempted under the same conditions as in Examples 1 to 3, but extrusion was performed at a stage in the middle of the reaction. The viscosity of the resin increased abnormally in the machine cylinder, making kneading and extrusion impossible. Table of the results
Shown in 1.

The above physical properties are measured by the following methods.

1. Tensile test: ASTM D638 2. Bending test: ASTM D790 3. Dynamic friction coefficient: JIS K 7218A (mate material SUS304 speed 4 cm / s, load 2 kgf holding time 30 min) [Effect] For the first time with the modified polystyrene resin of the present invention,
While maintaining the original mechanical strength of polystyrene resin, sliding properties such as releasability during molding, abrasion resistance, lubricity, and lubricity of the surface of molded products were improved and modified.

By containing the modified polystyrene resin of the present invention, the styrene polymer retains the original mechanical strength of the polystyrene resin, mold releasability during molding, abrasion resistance, lubricity, lubrication of the surface of the molded product. It has become possible to improve and modify the slidability such as properties. This is because the modified polystyrene resin of the present invention has excellent compatibility with the styrene polymer and the mechanical strength is not lowered.

The modified polystyrene resin of the present invention is easier to control its structure, particularly the structure of the polysiloxane part, as compared with the conventional modification method. It is possible to make the ratio with the siloxane moiety an optimal structure, and it has become possible to flexibly respond to the variety of requirements that come from the wide range of uses of styrene-based polymers.

Claims (9)

(57) [Claims] 1. A method for producing a modified polystyrene resin, which comprises reacting a reactive polysiloxane having an amino group at one end with a styrene copolymer containing a maleic anhydride unit. 2. A styrene-based copolymer containing a maleic anhydride unit has a maleic anhydride unit content of 0.01 to 20% by weight.
2. The method for producing a modified polystyrene resin according to item 1, wherein the modified polystyrene resin is a styrene copolymer. 3. The modified polystyrene system according to claim 1, wherein the reactive polysiloxane having an amino group at one end is a reactive polysiloxane having a weight average molecular weight of 100,000 or less. Resin manufacturing method. 4. When reacting a reactive polysiloxane having an amino group at one end with a styrene-based copolymer containing a maleic anhydride unit, styrene containing a maleic anhydride unit of the reactive polysiloxane. The method for producing a modified polystyrene resin according to any one of items 1 to 3, characterized in that the proportion of the modified polystyrene resin is 0.05 to 70% by weight. 5. A method for producing a modified polystyrene resin composition, which comprises mixing the modified polystyrene resin according to any one of claims 1 to 4 with a styrene polymer. 6. A modified polystyrene resin characterized by reacting a styrene copolymer containing a maleic anhydride unit with a reactive polysiloxane having an amino group at one end in the presence of a styrene polymer. A method for producing a composition. 7. A styrene-based copolymer containing a maleic anhydride unit has a maleic anhydride unit content of 0.01 to 20% by weight.
7. The method for producing a modified polystyrene resin composition according to item 6, wherein the modified polystyrene resin composition is a styrene copolymer. 8. The modified polystyrene system according to claim 6 or 7, wherein the reactive polysiloxane having an amino group at one end is a reactive polysiloxane having a weight average molecular weight of 100,000 or less. A method for producing a resin composition. 9. The styrene-based polymer is one kind of polymer selected from the group consisting of styrene polymers and styrene copolymers, or a mixture of two or more kinds of polymers, which is characterized in that Item 9. A method for producing a modified polystyrene resin composition according to any one of items 8.