| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | October 31, 2000 |
| PATENT TITLE |
Chlorinated vinyl chloride resin composition |
| PATENT ABSTRACT |
A chlorinated vinyl chloride resin composition, which is suitably used for the production of extruded pipes, containing a chlorinated vinyl chloride resin which has a polymerization degree of from 600 to 1500 prior to chlorination and a chlorination degree of from 62 to 70 wt. %, methyl methacrylate-butadiene-styrene copolymer particles having a butadiene content of less than 60 wt. % and a styrene content of larger than 30 wt. % in the whole particles, and a chlorinated polyethylene having a chlorine content of from 10 to 50 wt. %, in which the methyl methacrylate-butadiene-styrene copolymer particles have an average dispersed particle size of 2,000 angstroms or less in an extruded pipe produced from the composition. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | December 22, 1998 |
| PATENT FOREIGN APPLICATION PRIORITY DATA | This data is not available for free |
| PATENT REFERENCES CITED | Database WPI; Derwent Publications Ltd.; Class A14; AN 96-272832; XP002098296; JP 08 113685; (Sekisui Chem Ind Co Ltd.); May 7, 1996. |
| PATENT CLAIMS |
What is claimed is: 1. A chlorinated vinyl chloride resin composition for use in the production of an extruded pipe comprising 100 wt. parts of a chlorinated vinyl chloride resin which has a polymerization degree of from 600 to 1500 prior to chlorination and a chlorination degree of from 62 to 70 wt. %, 3 to 15 wt. parts of methyl methacrylate-butadiene-styrene copolymer particles having a butadiene content of less than 60 wt. % and a styrene content of larger than 30 wt. % in the whole particles, and 1 to 5 wt. parts of a chlorinated polyethylene having a chlorine content of from 10 to 50 wt. %, wherein said methyl methacrylate-butadiene-styrene copolymer particles have an average dispersed particle size of 2,000 angstroms or less in an extruded pipe produced from said composition. 2. A chlorinated vinyl chloride resin composition according to claim 1, wherein said methyl methacrylate-butadiene-styrene copolymer particles have a Vicat softening point of at least 60.degree. C. under a load of 1 kg. 3. A chlorinated vinyl chloride resin composition according to claim 1, wherein said chlorinated polyethylene has a chlorine content of from 30 to 40 wt. %. 4. A chlorinated vinyl chloride resin composition according to claim 1, wherein the amount of said methyl methacrylate-butadiene-styrene copolymer particles is from 4 to 12 wt. parts per 100 wt. parts of said chlorinated vinyl chloride resin. 5. A chlorinated vinyl chloride resin composition according to claim 1 which further comprises 1.5 to 5 wt. parts of a stabilizer and 1.5 to 4 wt. parts of a lubricant, per 100 wt. parts of said chlorinated vinyl chloride resin. 6. A method for the production of a pipe of a chlorinated vinyl chloride resin comprising extruding a chlorinated vinyl chloride resin composition of claim 1 to form the pipe. |
| PATENT DESCRIPTION |
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chlorinated vinyl chloride resin composition. In particular, the present invention relates to a chlorinated vinyl chloride resin composition suitable for the production of extruded pipes. 2. Prior Art Shaped articles of chlorinated vinyl chloride resin compositions have characteristics such as high heat resistance and are used at relatively high temperatures at which conventional vinyl chloride resin compositions cannot be used due to thermal deformation. For example, the shaped articles of chlorinated vinyl chloride resin compositions are used in the form of a pipe for hot water by making use of the high thermal deformation temperature which is 20 to 40.degree. C. higher than that of the shaped articles of vinyl chloride resin compositions. Furthermore, when pipes are produced, chlorinated vinyl chloride resins can be shaped with a conventional extruder for vinyl chloride resins. The use of such an extrusion method is one reason for that the chlorinated vinyl chloride resin can be widely used. However, chlorinated vinyl chloride resins have a drawback that they have inferior thermal stability to vinyl chloride resins, and thus they tend to be burnt in a shaping process. For example, a chlorinated vinyl chloride resin is colored when it is extrusion molded to produce a pipe for hot water, or in some cases, it is burnt during extrusion molding. Thus, such a produced pipe may not be commercially sold. In addition, when a chlorinated vinyl chloride resin is extruded in the form of a pipe for hot water, the die pressure and extrusion torque of an extruder increase, and the resin is burnt. To prevent burning, with a conventional extruder for vinyl chloride resins, the discharge amount of chlorinated vinyl chloride resins should be decreased in comparison with vinyl chloride resins to reduce the die pressure and extrusion torque. That is, when extruded pipes are produced from chlorinated vinyl chloride resins, the discharge amount of the resins is low, and thus the productivity of the pipes decreases. SUMMARY OF THE INVENTION One object of the present invention is to provide a chlorinated vinyl chloride resin composition suitable for the production of extruded pipes, which has good thermal stability, and can increase the discharge amount of the composition during extrusion and thus improve the productivity. Accordingly, the present invention provides a chlorinated vinyl chloride resin composition for use in the production of an extruded pipe comprising 100 wt. parts of a chlorinated vinyl chloride resin which has a polymerization degree of from 600 to 1500 prior to chlorination and a chlorination degree of from 62 to 70 wt. %, 3 to 15 wt. parts of MBS (methyl methacrylate-butadiene-styrene copolymer) particles having a butadiene content of less than 60 wt. % and a styrene content of larger than 30 wt. % in the whole particles, and 1 to 5 wt. parts of a chlorinated polyethylene having a chlorine content of from 10 to 50 wt. %, wherein said MBS particles have an average dispersed particle size of 2,000 angstroms (.ANG.) or less in an extruded pipe produced from said composition. DETAILED DESCRIPTION OF THE INVENTION A vinyl chloride resin (prior to post-chlorination) has a polymerization degree of from 600 to 1500, preferably from 600 to 1300. The chlorination degree of the chlorinated vinyl chloride resin is from 62 to 70 wt. %, preferably from 65 to 70 wt. %. When the polymerization degree of a vinyl chloride resin as the raw material of a chlorinated vinyl chloride resin is less than 600, sufficient mechanical strength cannot be attained. When this polymerization degree exceeds 1500, the processing of the resin composition is not easy. When the chlorination degree of a chlorinated vinyl chloride resin is less than 62 wt. %, a resin composition does not have sufficient heat resistance. When the chlorination degree exceeds 70 wt. %, the resin has a high melt viscosity, and thus the processing of a resin composition undesirably encounters technical problems. Herein, "vinyl chloride resins" include vinyl chloride homopolymers, and also copolymers of vinyl chloride with 20 wt. % or less of at least one other copolymerizable monomer (e.g. ethylene, propylene, vinyl acetate, allyl chloride, allyl glycidyl ether, acrylate esters, vinyl ethers, etc.). The MBS particles used in the present invention has a butadiene content of less than 60 wt. % and a styrene content of larger than 30 wt. %, in the whole particles. When the butadiene content in the MBS particles is 60 wt. % or more, a die pressure and an extrusion torque increase during the extrusion of the composition to produce pipes. Therefore, a feeding amount should be suppressed to decrease a discharge amount, and thus the productivity of the pipes deteriorates. The styrene content in the MBS particles should be larger than 30 wt. % to improve the flowability of the chlorinated vinyl chloride resin and thus increase the discharge amount of the composition. The amount of MBS particles is from 3 to 15 wt. parts per 100 wt. parts of the chlorinated vinyl chloride resin. When the amount of MBS particles is less than 3 wt. parts, the impact resistance of the pipes deteriorates. When the amount of MBS particles exceeds 15 wt. parts, the heat resistance inherent in the chlorinated vinyl chloride resins tends to decrease. The amount of MBS particles is preferably from 4 to 12 wt. parts from the viewpoint of the balance between the impact resistance and heat resistance of the produced pipes. The MBS particles in the extruded pipes have an average dispersed particle size of 2,000 .ANG. or less, preferably 1,800 .ANG. or less to improve the impact resistance of the pipes. The lower limit of the average dispersed particle size of the MBS particles is not limited, but is usually 1,000 .ANG.. The average dispersed particle size of the MBS particles can be measured by a conventional method. For example, a composition mass is cut in the form of a sample piece of about 5 mm square, and dyed by an osmic acid dyeing method (dipping the sample piece in a 1 wt. % aqueous solution of osmic acid). Then, the sample piece is very thinly sliced and observed with a transmission electron microscope. The MBS particles are seen as black circles, and their diameters are measured and averaged. It is preferable to use MBS having a Vicat softening point of at least 60.degree. C. under a load of 1 kg to increase a discharge amount by increasing a feed amount while suppressing a die pressure and an extrusion torque during the extrusion process of pipes. The Vicat softening point of MBS usually does not exceed 90.degree. C. According to the present invention, the chlorinated vinyl chloride resin composition contains 1 to 5 wt. parts of a chlorinated polyethylene having a chlorine content of from 10 to 50 wt. %, per 100 wt. parts of the chlorinated vinyl chloride resin, to increase a discharge amount through the decrease of a die pressure and an extrusion torque during the extrusion process of pipes. When the chlorine content of the chlorinated polyethylene is outside the above range, the compatibility of the chlorinated polyethylene with the chlorinated vinyl chloride resin as a base resin deteriorates, and thus the extruded pipes tend to have insufficient impact strength. The chlorinated polyethylene preferably has a chlorine content of from 30 to 40 wt. % to improve the impact strength of the extruded pipes. When the amount of the chlorinated polyethylene is less than 1 wt. parts, it is difficult to achieve the effect to increase a discharge amount through the suppression of a die pressure and an extrusion torque. When the amount of the chlorinated polyethylene exceeds 5 wt. parts, the heat resistance inherent in the chlorinated vinyl chloride resin deteriorates. The chlorinated vinyl chloride resin composition of the present invention may preferably contain stabilizers and/or lubricants, in addition to the MBS particles and the chlorinated polyethylene. Stabilizers may be any conventional stabilizers for chlorinated vinyl chloride resins such as tin-base stabilizers, lead-base stabilizers, etc. Among them, tin-base stabilizers are preferable. Preferable examples of tin-base stabilizers are alkyltin compounds (e.g. methyltin, butyltin, octyltin, mixed metal alkyltin, dialkyltin dicarboxylate salts, etc.). Other examples of tin-base stabilizers are mercaptomethyltin, mercaptooctyltin, mercaptobutyltin, dialkyltinbis (alkylmercaptocarboxylate salt), di-n-octyltin-S,S'-bis(isooctylmercaptoacetate), butyltin maleate polymer, butyltin maleate ester, octyltin maleate polymer, octyltin maleate ester, etc. The amount of a stabilizer is preferably from 1.5 to 5 wt. parts per 100 wt. parts of a chlorinated vinyl chloride resin. When the amount of a stabilizer is less than 1.5 wt. parts, the thermal stability of a chlorinated vinyl chloride resin composition may not be improved. When the amount of a stabilizer exceeds 5 wt. parts, the effect to improve the thermal stability reaches the limit, and thus the thermal stability will not be improved in a degree comparable to the added amount of the stabilizer. Lubricants may also be any conventional ones. Examples of lubricants are polyglycerol of di- or trioleate, polyethylene, oxidized polyethylene, high molecular weight paraffin waxes, etc. Among them, polyethylene waxes are preferable. The amount of a lubricant is preferably from 1.5 to 4 wt. parts per 100 wt. parts of a chlorinated vinyl chloride resin. When the amount of a lubricant is less than 1.5 wt. parts, the composition has a high melt viscosity, and thus its extrusion precessability deteriorates. When the amount of a lubricant exceeds 4 wt. parts, the lubricity of the resin against metals becomes too high, and thus the composition may pulsate when it is discharged in the extrusion processing process. The chlorinated vinyl chloride resin composition of the present invention may optionally contain other additives, which are compounded in conventional chlorinated vinyl chloride resin compositions, in addition to the above additives. Examples of the other additives are fillers (e.g. titanium dioxide, calcium carbonate, etc.), colorants, and the like. The chlorinated vinyl chloride resin composition of the present invention may be prepared by compounding and kneading the above essential and optional components with any conventional mixing and kneading apparatuses. The chlorinated vinyl chloride resin composition of the present invention is used particularly to produce extruded pipes, although it may be used to produce other shaped products which are produced from conventional chlorinated vinyl chloride resins. |
| PATENT EXAMPLES | available on request |
| PATENT PHOTOCOPY | available on request |
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