CA2048362A1 - Polyvinyl chloride resin-based composition - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
An improved polyvinyl chloride resin-based molding compo-sition is proposed which has good workability in molding and capa-ble of giving rigid shaped articles having high flexural elastic modulus, good heat resistance and excellent impact strength. The composition comprises: (a) 100 parts by weight of a polyvinyl chlo-ride resin having an average degree of polymerization in the range from 1000 to 2300; (b) from 6 to 17 parts by weight of a chlorinated polyethylene of a specified chlorine content, a partially crosslinked acrylonitrile-butadiene copolymeric rubber, of which the content of soluble fraction in tetrahydrofuran isa 30% to 50% by weight, or a combination thereof; and. (c) from 2 to 7 parts by weight of a buta-diene-styrene copolymeric rubber.

Description

POLYVINYL C~ILORIDE RESIN-BASED COMPOSITION

BACKGROUND OF THE INVENTION
The present invention relates to a polyvinyl chloride resin-based composition or, more particularly, to a polyvinyl chloride resin-based composition suitable for molding of various kinds of rigid shaped articles such as building materials, e.g., eave troughs and window sashes, furniture, interior decorations, signboards and the like for which good workability in molding, high elastic modu-lus in bending, excellent impact resistance and the like are essen-tial.
As is well known, many rigid shaped articles including build-ing materials such as eave troughs, window sashes and the like are prepared by molding a polyvinyl chloride resin-based composition because these resin-molded articles can be prepared at a relatively low cost and have beautiful appearance. Applicantion fields of polyvinyl chloride resins as a material of rigid shaped articles are rapidly expanding in recent years to include various interior and outdoor structural bodies, furniture and the like having a very complicated structure.
One of the disadvantages in these resin-molded rigid articles is that their impact resistance is low so that they are readily bro-ken when an impact force is added thereto. Japanese Patent Kokai No. 60-179443 teaches that the resin composition can be improved in this regard by compounding with a chlorinated polyethylene.

20~8362 Though not ineffective, the improvement obtained by this method is under limitation rather with a disadvantage due to a decrease in the flexural elastic strength. The resin composition as a material of complicated structural bodies mentioned above is required to have good workability in molding and high flexural elastic modu-lus while the improvement in this regard obtained by compound-ing with a chlorinated polyethylene is not high enough.

SUMMARY OF THE INV~3NTION
The present invention accordingly has an object to provide a novel polyvinyl chloride resin-based composition or molding com-pound having excellent workability in molding such as ~lowability of the composition at an elevated temperature and capable of giv-ing rigid shaped articles such as interior and outdoor structural bodies, furniture and the like having high flexural elastic modulus and excellent impact strength and heat resistance.
Thus, the polyvinyl chloride resin-based composition of the invention comprises, as a blend:
(a) 100 parts by weight of a polyvinyl chloride resin having an average degree of polymerization in the range from 1000 to 2300;
(b) from 6 to 17 parts by weight of a chlorinated polyethylene, of which the content of chlorine is in the range from 25 to 45% by weight, a partially crosslinked acrylonitrile-butadiene copolymer-ic rubber, of which the content of soluble fraction in tetrahydro-furan is in the range from 20% to 50% by weight, or a combination thereof; and 20483~2 (c) from 2 to 7 parts by weight of a butadiene-styrene copolymeric rubber.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As is described above, the essential ingredients in the inven-tive resin composition include the components (a), (b) and (c), of which the basic ingfredient is the component (a) which is a poly-vinyl chloride resin having a specified average degree of polymer-ization. The polyvinyl chloride resin here implied includes not only homopolymers of vinyl chloride but also copolymers of vinyl chlo-ride with other comonomers copolymerizable therewith such as the copolymers of vinyl chloride and maleimide, ethylene, vinyl ace-tate, vinylidene chloride and the like provided that the weight fraction of the vinyl chloride moiety therein is at least 50% as well as chlorinated polyvinyl chloride resins. The average degree of polymerization of the resin should be in the range from 1000 to 2300. When the average degree of polymerization of the resin is too small, the shaped articles prepared by molding the resin compo-sition of such a polyvinyl chloride resin would be poor in the rigid-ity charactèristics such as impact strength, tensile strength, flex-ural elasticity and the like while, when it is too large, sufficient flowability of the resin composition in molding can be obtained only by unduly increasing the temperature eventually to cause thermal decomposition of the resin and decrease in the physical properties of the shaped articles prepared from the resin composi-tion.

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~4- 2~83~2 The component (b) is a chlorinated polyethylene, a partially crosslinked copolymeric rubber of acrylonitrile and butadiene or a combination thereof. The chlorinated polyethylene as the compo-nent (b) should preferably contain from 25 to 45% by weight of chlorine. Chlorinated polyethylenes to satisfy this requirement can be commercially obtained. When the component (b) is the par-tially crosslinked copolymeric rubber of acrylonitrile and butadi-ene, the content of the fraction soluble in tetrahydrofuran should not e~ceed 50% by weight or, preferably, in the range from 20% to 50% by weight. When the content of the soluble fraction in the co-polymeric rubber is too large, no sufficient improvement could be obtained in the impact strength of the shaped articles prepared from the resin composition. Commercial products of partially crosslinked copolymeric rubber of acrylonitrile and butadiene to satisfy this requirement are available on the market.
The above mentioned soluble fraction in the partially cross-linked copolymeric rubber can be determined in the following manner. Thus, a 1 g portion of the rubber in a finely divided form is taken in a colorimetric tube of 100 ml capacity together with 180 ml of tetra~iydrofuran. The tube is stoppered and shaken for 5 rnin-utes at 75 to 85 C followed by cooling to room temperature. A por-tion of fresh tetrahydrofuran is added to the tube to make up a to-tal volume of 100 ml and then the tube is again stoppered and vigo-rously shaken. After standing of the stoppered tube for 24 hours, a 10 ml portion of the supernatant liquid is taken by using a pipette and dried by evaporating the solvent to leave a solid matter which .~. :

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20~8362 is the soluble fraction in the partially crosslinked copolymeric rubber.
The amount of the component (b) in the inventive resin com-position is in the range from 6 to 17 parts by weight per 100 parts by weight of the polyvinyl chloride resin as the component (a).
When the amount of the component (b) is too small, no sufficient improvement can be obtained in the impact strength of the shaped articles prepared *om the resin composition by molding. When the amount of the component (b) is too large, on~ the other hand, a de-crease is~caused in the flowability of the resin composition at an elevated temperature for molding and the shaped articles prepared from the resin composition would have poor rigidity characteris-tics with a low flexural elastic modulus. In a preferable embodi-ment of the invention, the component (b) is a combination of the chlorinated polyethylene and the partially crosslinked copolymer-ic rubber in amounts of from 6 to 10 parts by weight~and from 2 to 7 parts by welght, respectively, per 100 parts by weight of the com-ponent (a). ~ ;
The camponent (c) is a copolymeric rubber of styrene and bu-, tadiene or a so-called SBR which is not particuiarly limitative to a specific type. A preferable copolymeric rubber, however, is a so-called S-B-S type rubber having a block-wise molecular structure consisting of a sequence of the styrene moiety S, butadiene moiety B and styrene moiety S. The copolymeric ratio of styrene and buta-diene therein is in the range from 25:75 to 50:50 by weight or, pre-ferably, from 35:65 to 45:55 by weight. Further, the copolymeric -, ,.:-- . ~ -: - ~. :, . - - . :
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-6- 20~8362 rubber should have a melt index of at least 1 per 10 minutes or, preferably, at least 20 per 10 minutes at 200 C under a load of 5 kg in order to exhibit good flowability in molding.
The amount of the component (c) in the inventive resin com-position is in the range from 2 to 7 parts by weight per 100 parts by weight of the polyvinyl chloride resin as the component (a). When the amount of the component (c) is too small, no sufrlcient im-provement can be obtained in the flowability of the resin compo-sition at an elevated temperature for molding. When the amount thereof is too large, on the other hand, an undue decrease is caused in the impact strength of the shaped articles obtained by molding the resin composition.
Although the essential ingredients in the inventive resin composition are the above described components (a), (b) and (c)~ it is usual that the resin composition is compounded with a stabilizer exemplified by metal soap stabilizers such as dibasic lead stearate, barium stearate, calcium stearate, zinc stearate and the like, orga-nic tin-containing stabilizers such as dibutyl tin dilaurate, dioctyl tin maleate, dibutyl tin dilauryl mercaptide and the like and lead-bas-ed stabilizers such as tribasic lead sulfate, lead silicate, dibasic lead phosphite and the like either alone or as a combination of two kinds or more according to need.
It is further optional according to need that the inventive res-in composition is compounded with various kinds of known addi-tives conventionally used in polyvinyl chloride resin-based compo-sitions including auxiliary stabilizers such as epoxy compounds, , , : .

- 20~83~i2 lubricants such as polyethylene waxes, fatty acid amides, esters of a fatty acid and a polyhydric alcohol and the like, inorganic fillers such as calcium carbonate or, in particular, precipitated light cal-cium carbonate and the like, mold-release agents, coloring agents, antioxidants, ultraviolet absorbers and so on each in a limited amount.
The inventive poly~inyl chloride resin-based composition can be prepared by uniformly blending the above described essential and optional ingredients each in a specified amount by using a suitable resin processing machine such as high-speed mixers and the like and converting the blend into particles of powder or pellets which can be molded into shaped articles by a conventional mold-ing method such as calendering, extrusion molding, injection molding, blow molding and the like.
In the following, the polyvinyl chloride resin-based composi-tion of the present invention is described in more detail by way of examples which, however, never limit the scope of the invention in any way. The term of "parts" given below always refers to "parts by weight".
Example 1;
A resin composition was prepared by uniformly blending and kneading, on a 6-inch two-roller mill for 5 minutes at 170 C:
100 parts of a polyvinyl chloride resin having an average degree of polymerization of 1700 (TK-1700, a product by Shin-Etsu Chemical Co.);
10 parts of a chlorinated polyethylene containing 20483~2 31.5% by weight of chlorine (Elathrene 301A, a product by Showa Denko Co.);
3 parts of a straight-chain S-B-S type styrene-butadiene block-copolymeric rubber of which the styrene:butadiene weight ratio was 40:60 and the melt index was 50 perlO minutes (Cariflex TRK~ 1383, a product by Shell Petroleum Co.);
l part of an organic tin-containing stabilizer (T-17NJ, a product by Katsuda Kako Co.), referred to as the stabilizer A hereinbelow;
0.7 part of calcium stearate, referred to as the stabilizer B hereinbelow;
6 parts of calcium carbonate filler ( Whiton SB, a product by Shiraishi Kogyo Co.); and 0.5 part of a polyethylene wax (AC-6A, a product by Allied Chemical Co.) as a lubricant.
The resin composition was subjected to the test of flowability and shaped into a sheet having a thickness of 1 mm which was sub-jected to the tests of the impact strength, heat resistance and flex-ural bending for evaluation. The testing procedures were as given below and the results are shown in Table 1.

Flowability of the resin composition Measurements were undertaken by using a Koka-Type Flow Tester at 200 C under a load of 200 kg/cm2.
Impact stren~th "
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204s362 Pieces of the above prepared 1 mm thick sheet were pressed together and integrated by pressing at 175 C for 5 minutes into a plate having a thickness of 3 mm, of which the Izod impact test was conducted according to the procedure specified in JIS K 7110.
Heat resistance The above prepared 3 mm thick plate was subjected to the measurement of the Vicat softening point.
Flexural elasticitY
A 4 mm thick plate prepared from the 1 mm thick sheets in a similar manner to the above was subjected to. the measurement ac-cording to the procedure specified in JIS K 7203.

Example 2.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 1 except that the amount of the styrene-butadiene copolymeric rubber was increased to 5 parts instead of 3 parts. The results of the testings are shown also in Ta-blel.
Example 3.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 1 except that the amount of the chlorinated polyethylene was decreased to 7 parts instead of 10 parts. The results of the testings are shown also in Table 1.
Example 4.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 3 except that the polyvinyl - - ~ . . - . . . .
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204836~

chloride resin (TK-1300, a product by Shin-Etsu Chemical Co.) us-ed here had an average degree of polymerization of 1300 instead of 1700. The results of the testings are shown also in Table 1.
Example ~.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 3 except that the polyvinyl chloride resin (TK-2000, a product by Shin-Etsu Chemical Co.) us-ed here had an average degree of polymerization of 2000 instead of 1700. The results of the testings are shown also in Table 1.
Exam~le 6.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 3 except that the styrene-butadiene copolymeric rubber was replaced with the same amount of another straight-chain S-B-S type styrene-butadiene block-co-polymeric rubber of which the styrene:butadiene weight ratio was 30:70 and the melt index was smaller than 1 per 10 minutes (Cari-flex TR 1101, a product by Shell Petroleum Co.). The results of the testings are shown also in Table 1.
Example 7.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 1 except that 10 parts of the chlorinated polyethylene Elathrene 301A was replaced with 7 parts of another chlorinated polyethylene (Elathrene 401~, a pro-duct of the same company as Elathrene 301~) containing 39.5% by weight of chlorine. The results of the testings are shGwn also in Table 1.

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Comparative Examplel The formulation of the resin composition and the testing pro-ceedures were the same as in Example 3 excepting omission of the styrene-butadiene copolymeric rubber. The results of the testings are shown also in Table 1.
Comparative Example 2.
The formulation of the resin composition and the testing pro-ceedures were the same as in Example 1 except that the amount of the styrene-butadiene copolymeric rubber was increased to 10 parts instead of 3 parts. The results of the testings are shown also in Table 1.
Comparative Example 3.
The formulation of the resin composition and the testing pro-ceedures were the same as in Example 1 except that the amount of the chlorinated polyethylene was decreased to 5 parts instead of 10 parts. The results of the testings are shown also in Table 1.
Comparative Example 4.
The formulation of the resin composition and the testing pro-ceedures were the same as in Example 1 except that the amount of the chlorirlated polyethylene was increased to 20 parts instead of 10 parts. The results of the testings are shown also in Table 1.
Comparative Example 5.
The formulation of the resin composition and the testing pro-ceedures were the same as in Example 3 except that the polyvinyl chloride resin (TK-800, a product by Shin-Etsu Chemical Co.) us--12- 20~83~2 ed here had an average degree of polymerization of 800 instead of 1700. The results of the testings are shown also in Table 1.
Example 8.
~ resin composition was prepared, in substantially the same manner as in Example 1, from:
100 parts of the same polyvinyl chloride resin as used in Example l;
3 parts of the same styrene-butadiene copolymeric rubber as used in Example l;
10 parts of a partially crosslinked acrylonitrile-butadiene copolymeric rubber, containing 31% by weight of a fraction soluble in tetrahydrofuran (Hycar 1411, a product by Nippon Zeon Co.), referred to as NBR hereinbelow;
1 part of the same tin-containing stabilizer as used in Example l;
1 part of calcium stearate;
5 parts of the same calcium carbonate filler as used in Example l; and 0.5 part of the same lubricant as used in Example 1.
The testing procedures of this resin composition were just the same as in Example 1 to give the results shown in Table 1.
Example 9.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 8 except that the polyvinyl chloride resin (TK-2000, a product by Shin-Etsu Chemical Co.) us-, .
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2~83B2--13--ed here had an average degree of polymerization of 2000 instead of 1700. The results of the testings are shown also in Table 1.
Example 10.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 8 except that the polyvinyl chloride resin (TK-1300, a product by Shin-Etsu Chemical Co.) us-ed here had an average degree of polymerization of 1300 instead of 1700. The results of the testings are shown also in Table 1.
Comparative Example 6.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 8 excepting omission of the styrene-butadiene copolymeric rubber. The results of the testings are shown also in Table 1.
Comparative Example 7.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 8 except that the amount of the styrene-butadiene copolymeric rubber was increased to 10 parts instead of 3 parts. The results of the testings are shown also in Table 1.
ComParative Example 8.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 8 except that the amount of the NBR was decreased to 5 parts instead of 10 parts. The results of the testings are shown also in Table 1.

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-` 20~8362 Compara~ti~e Example 9.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 8 except that the polyvinyl chloride resin (TK-700~ a product by Shin-Etsu Chemical Co.) us-ed here had an average degree of polymerization of 700 instead of 1700. The results of the testings are shown alsn in Table 1.
Comparat_e Example 10.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 8 except that the polyvinyl chloride resin (TK-2500, a product by Shin-Etsu Chemical Co.) us-ed here had an average degree of polymerization of 2500 instead of 1700. The resuits of the testings are shown also in Table 1.
Comparative Example 11.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 8 except that the amount of the NBR was increased to 30 parts instead of 10 parts..The results of the testings are shown also in Table 1.
Example 11.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 8 except that the amount of the calcium carbonate ~lller was increased to 6 parts instead of 5 parts, the amount of the NBR was decreased to 5 parts instead of 10 parts and 7 parts of the same chlorinated polyethylene as used in Example 1 were additionally added. The results of the testings are shown also in Table 1.

20~8362 Example 12.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 11 except that the amount of the styrene-butadiene copolymeric rubber was increased to 5 parts instead o~ 3 parts. The results of the testings are shown also in Table 1.
Exam~le 12.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 11 except that the amount of the chlorinated polyethylene was increased to 10 parts instead of 7 parts. The results of the testings are shown also in Table 1.
Example 14.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 11 except that the amount of the NBR was decreased to 3 parts instead of 5 parts. The results of the testings are shown also in Table 1.
Example 15.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 11 except that the amount of the NBR was increased to 10 parts instead of 5 parts. The results of the testings are shown also in Table 1.
Example 16.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 11 except that the polyvinyl chloride resin (TK-1300, a product by Shin-Etsu Chemical Co.) us-, 20483~2--16 ed here had an average degree of polymerization of 1300 instead of 1700. The results of the testings are shown also in Table 1.
Exam~le 17.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 11 except that the polyvinyl chloride resin (TK-2000, a product by Shin-Etsu Chemical Co.) us-ed here had an average degree of polymerization of 2000 instead of 1700. The results of the testings are shown also in Table 1.
Comparative Example 12.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 11 except that the amount of the chlorinated polyethylene was increased to 20 parts instead of 7 parts. The results of the testings are shown also in Table 1.
Comparative Example 13.
The formulation of the resin composition and the testing pro-cedures were the same as in Example 11 except that the amount of the NBR was increased to 20 parts instead of 5 parts. The results of the testings are shown also in Table 1.
Comparative Exaniple 14.
The f~rmulation of the resin composition and the testing pro-cedures were the same as in Example 11 except that the polyvinyl chloride resin (TK-2500, a product by Shin-Etsu Chemical Co.) us-ed here had an average degree of polymerization of 2500 instead of 1700 and the amount of the chlorinated polyethylene was decreas-ed to 5 parts instead of 7 parts. The results of the testings are shown also in Table 1.

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20~83~2 Table 1 Flowability Izod impact Vicat soften- Flexuralo~resin com- strength, ing point, C elastic modu-position, ml/ kg/cm2 lus, kg/mm2 second X 10-2 Example 3.14 113 92.6 198 2 3.71 88 90.7 188 3 2.61 95 92.9 220 4 3.31 76 90.5 220 2.43 110 95.1 241 6 1.92 96 93.2 235 7 2.51 92 95.5 232 Comparative Example 1.04 20 92.9 240 2 4.88 51 89.7 ~68 3 2.03 25 93.8 237 4 5.11 *) 88.2 153 3.96 10 88.5 215 Example 8 2.85 101 91.5 208 9 2.01 110 92.3 208 3.00 85 90.9 185 Comparative Example 6 1.00 6 92.1 194 7 2.95 38 86.2 156 8 3.10 18 92.4 248 9 3.21 12 85.7 178 1.21 125 93.0 215 11 0.91 *) 85.6 115 -2~4~3~2 T a b l e 1 (continued) Flowability Izod impact Vicat soften- Flexural of resin com- strength, ing point, C elastic modu-position, ml/ kg/cm2 lus, kg/mm second X 1o-2 Example 11 2.13 145 89 209 12 2.57 129 88 195 13 2.59 156 86 187 14 2.50 138 91 217 1,72 1~7 87 lso 16 2.~5 120 88 204 17 1.94 149 93 221 Comparative Example 12 3.8~ *) 77 139 13 0.94 *) 79 141 14 0.87 14 95 223 *) test specimen not broken . . .

Claims (5)

1. A polyvinyl chloride resin-based composition which compris-es, as a blend:
(a) 100 parts by weight of a polyvinyl chloride resin having an average degree of polymerization in the range from 1000 to 2300;
(b) from 6 to 17 parts by weight of a chlorinated polyethylene, of which content of chlorine is in the range from 25% to 45% by weight, a partially crosslinked acrylonitrile-butadiene copolymer-ic rubber, of which the content of soluble fraction in tetrahydro-furan is in the range from 20% to 50% by weight, or a combination thereof; and (c) from 2 to 7 parts by weight of a butadiene-styrene copolymeric rubber.

2. The polyvinyl chloride resin-based composition as claimed in claim 1 in which the component (b) is a combination of from 6 to 10 parts by weight of the chlorinated polyethylene and from 2 to 7 parts by weight of the partially crosslinked acrylonitrile-butadi-ene copolymeric rubber.

3. The polyvinyl chloride resin-based composition as claimed in claim 1 in which the copolymerization ratio of styrene and butadi-ene in the partially crosslinked acrylonitrile-butadiene copolym-eric rubber is in the range from 25:75 to 50:50 by weight.

4. The polyvinyl chloride resin-based composition as claimed in claim 1 in which the partially crosslinked acrylonitrile-butadiene copolymeric rubber has a melt index of at least 1 per 10 minutes at 200 °C under a load of 5 kg.

5. The polyvinyl chloride resin-based composition as claimed in claim 1 which further comprises a stabilizer.