JPH0312579B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a thermoplastic elastomer composition, and more specifically, the surface of the molded product is flat, has excellent matte properties, has an extremely small residual strain rate due to applied external force, and is similar to ordinary vinyl chloride. The present invention relates to an improved vinyl chloride-based thermoplastic elastomer composition that can be processed using a molding machine. In general, vinyl chloride resins with a high average degree of polymerization,
It is well known that moldings with a soft, rubbery feel can be obtained by adding plasticizers. However, such soft vinyl chloride resin has a large creep property and therefore has a smaller restoring force after stress is applied compared to rubber.
Although it has the advantage of being easily molded by extrusion or injection, its use in products that require low compressive residual strain over a long period of time, such as packing, gaskets, or glass launch channels, is often limited. In addition, molded products made from vinyl chloride resin are generally glossy, and while this is used as an advantage, in recent years, matte electric wires with low reflection, parts for automobiles and home appliances with a high-class feel, etc. Matting performance is required for applications such as interior decoration products and sheets with excellent blocking resistance, and the resin itself has matting performance, so it can be matted without adding large amounts of fillers, processing at low temperatures, or embossing. Increasingly, products are required to be obtained. In order to meet these performance requirements, by increasing the degree of polymerization of vinyl chloride resins and copolymerizing vinyl chloride monomers with polyfunctional monomers, tetrahydrofuran (hereinafter referred to as
A method of manufacturing a resin that produces an insoluble gel (abbreviated as THF) and has the same effect as substantially increasing the average degree of polymerization, and a composition using a combination of these as a raw material resin have been proposed (Japanese Patent Publication No. 1983-
25346, Japanese Unexamined Patent Publication No. 57-111341). However, the resins or compositions obtained by these methods have high softening temperatures and extremely poor melt fluidity, resulting in poor moldability. The problem was that the desired physical properties could not be obtained unless appropriate processing machinery was used. As a method to solve these disadvantages and disadvantages, when producing the gel-containing vinyl chloride resin used, a suitable amount of a radically polymerizable polyfunctional oligomer or a polyfunctionally reactive low molecular weight polymer is added and copolymerized to produce a gel. A series of proposals have been made to use resins with adjusted gel densities and gel fractions as composition components (JP-A No. 58-47011, JP-A-Sho 56-
92024, Japanese Patent Publication No. 56-81328, Japanese Patent Publication No. 56-5843). By applying these methods, it is true that molding processability is significantly improved, but when copolymerizing polyfunctional monomers or reactive substances with vinyl chloride, even slight differences in polymerization reaction conditions can cause problems. The resulting gel density and gel fraction vary significantly, and therefore extremely strict control of polymerization conditions is required to obtain a composition with desired physical properties, making it impractical. The present inventors have discovered that without these difficulties, the surface of the molded product is flat, has good matte properties, and the residual strain rate due to applied external force is extremely small, and that it can be made from ordinary soft vinyl chloride. In order to obtain a composition to which a molding method for molding resin can be applied,
As a result of various studies, we found that a high polymerization degree polyvinyl chloride resin with an average polymerization degree of 2000 or more, a crosslinked polyvinyl chloride resin consisting of a substantially THF-insoluble gel, and a low polymerization degree polychloride resin with an average polymerization degree of 500 or less. The four essential ingredients are vinyl resin and plasticizer,
The present inventors have discovered that by preparing a composition in which stabilizers and fillers are added as necessary, it is surprisingly easy to obtain a composition that satisfies the above-mentioned physical properties, leading to the achievement of the present invention. That is, the present invention provides (a) a polyvinyl chloride resin with an average degree of polymerization (hereinafter simply referred to as average degree of polymerization) of 2000 or more as measured by the viscosity method of JIS K 6721;
Based on the weight part, (b) a polyfunctional monomer having two or more ethylenically unsaturated bonds in the molecule alone or a mixture, and vinyl chloride alone or a monomer mixture containing vinyl chloride as a main component (hereinafter referred to as vinyl chloride monomer) 20 to 90 parts by weight of a cross-linked polyvinyl chloride resin containing 80% by weight or more of THF-insoluble gel content obtained by copolymerizing (abbreviated); (c) low polymerization degree polyvinyl chloride with an average degree of polymerization of 500 or less based resin
In order to obtain a molded product with the desired hardness, (d) add 100 to 300 parts by weight of a plasticizer, and (e) add stabilizers, fillers, and coloring as necessary. Thermoplastic elasticity that produces molded products with a flat, matte surface and a low permanent deformation rate due to stress under the same conditions as when molding ordinary soft vinyl chloride resin with additives such as additives. Regarding body composition. The high polymerization degree vinyl chloride resin used in the present invention must be a polymer or copolymer mainly composed of vinyl chloride with an average degree of polymerization of 2,000 or more, and preferably an average degree of polymerization of 2,500 or more. good. If the degree of polymerization is less than 2000 and plasticized,
It is no different from ordinary soft vinyl chloride resin, and its elasticity and creep properties are different from those of rubber. There is no particular restriction on the upper limit of the degree of polymerization, but 6000
The following are preferably used. As mentioned above, the crosslinked vinyl chloride resin used in the present invention needs to contain a substantially THF-insoluble gel content of 80% by weight or more, more preferably 90% by weight or more. The resin is a vinyl chloride polymerization system containing diallyl adipate, diallyl azelate, diallyl sebacate,
Diallyl esters of ethylenically saturated and unsaturated dibasic acids such as diallyl maleate, diallyl fumarate, diallyl itaconate, diallyl esters of phthalic acid such as diallyl phthalate, diallyl isophthalate, diallyl terephthalate, diallyl carbinol, triaryl Lucyanurate, triallylisocyanurate, divinylbenzene,
Difunctional compounds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, glycerin triacrylate, glycerin trimethacrylate, polyethylene glycol diacrylate, polyethylene glycol methacrylate, 2,6-diacrylphenol, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, etc. It can be obtained by adding an appropriate amount of a functional or polyfunctional monomer and carrying out radical polymerization under conditions that will sufficiently produce a gel. With the coexistence of such crosslinking copolymer monomers, THF
Except for producing an insoluble gel, the polymerization method does not require any changes from the usual polyvinyl chloride polymerization method, and any polymerization method such as suspension polymerization, emulsion polymerization, or bulk polymerization may be used. . In the present invention, the use of a low polymerization degree vinyl chloride resin is the most important requirement for improving processability in the present invention, and the use of a vinyl chloride-based polymer or copolymer with an average degree of polymerization of 500 or less. It is necessary that there be. More preferably, it is 450 or less. When the degree of polymerization is 500 or more, the behavior during processing is not much different from that of commonly used vinyl chloride resins, and the object of the present invention cannot be achieved. Note that if the degree of polymerization of a low polymerization degree vinyl chloride resin is too low, it will be easily thermally decomposed, so the lower limit is preferably 400 or more. The high polymerization degree vinyl chloride resin, crosslinked vinyl chloride resin, and low polymerization degree vinyl chloride resin may be a copolymer mainly composed of vinyl chloride,
Examples of copolymerizable monomers include ethylene,
propylene, vinyl acetate, vinyl propionate,
Vinylidene halides, acrylic esters,
Examples include methacrylic acid esters, acrylonitrile, and alkyl vinyl ethers. Note that the vinyl chloride resin with a high degree of polymerization or a low degree of polymerization used in the present invention is not limited by its manufacturing method. The plasticizer used in the present invention is added to keep the molded product rubber-like at low temperatures and to adjust its hardness, and its type and amount are selected depending on the intended use of the molded product. Examples of plasticizers used include dibutyl phthalate, dioctyl phthalate, butylbenzyl phthalate, dioctyl adipate, dioctyl azelate, dioctyl sebacate, tricresyl phosphate, trioctyl trimellitate, tridecytrimeritate, and polyester plasticizers. agent, chlorinated paraffin, etc. The thermoplastic elastomer composition of the present invention may be used with the addition of stabilizers, fillers, colorants, processability improvers, etc., as required. Alternatively, it may be used by blending with other thermoplastic elastomer resins, rubbers, etc. Examples of processability improvers include liquid butadiene, chloroprene, isoprolene, 1,3-pentadiene, liquid silicone, etc., in addition to acrylic or methacrylic modified processing aids that are usually used as processing aids for vinyl chloride resins. Urethane rubber is also effective. Blends of ethylene/vinyl acetate copolymer, ABS, AS resin,
Chlorinated polyethylene, polyurethane, polyester, epoxy resin, EPDM, NBR, CR, CSM
etc. Hereinafter, the composition of the present invention will be explained in detail in Examples, but the present invention is not limited to these Examples unless the gist thereof is exceeded. Reference example: 50% stainless steel autoclave with 30% deionized water
After adding 12g of partially saponified polyvinyl alcohol, a polymerization initiator, and the polyfunctional monomer shown in Table 1, and completely removing the air inside, add 25kg of vinyl chloride monomer and bring to the specified temperature with stirring. The polymerization was carried out to form a crosslinked vinyl chloride resin. After drying and purifying the resulting crosslinked vinyl chloride resin, it was dissolved in THF, and the supernatant was separated using a high-speed centrifugal sedimentator with a centrifugal force of 20,000 g, and the dry weight fraction of the precipitated gel was determined. The results are also shown in Table 1.

[Table] Examples 1 to 4, Comparative Examples 1 and 2 Using 1 in Table 1 as the crosslinked vinyl chloride resin,
A high polymerization degree vinyl chloride resin, a low polymerization degree vinyl chloride resin, and a plasticizer were mixed as shown in Examples 1 to 4 in Table 2, and a Ca-Zn composite stabilizer (Tokyo Fine TMF362) was prepared.
Add 4 parts by weight, 3 parts by weight of epoxidized soybean oil, 10 parts by weight of calcium carbonate (Shiraishi Kogyo Shiroenka CC), and 7 parts by weight of coloring carbon (HMF, Tokai Electrode Seast 3), and mix in a Heensiel mixer with a volume of 9.
Dry-up was carried out at 80°C to obtain a thermoplastic elastomer composition. This composition was subjected to an extrusion test using a test device consisting of a 3/4'' screw manufactured by HAAKE in the United States, a test extruder Rheomex, and an ASTM Garvey type die, and the extrudability of method A according to ASTM D 2230 was evaluated. (The extrusion temperature was appropriately adjusted to a temperature different from that of this ASTM method.) Also, from the pellets of the strand cut of this extruder, test pieces were prepared according to the compression set test of JIS K 6301, and the values were measured. are as shown in Table 2. As a comparative example, Table 2 also shows the same characteristics of the present composition in which the crosslinked vinyl chloride resin or the low degree of polymerization vinyl chloride resin was removed.

[Table] These results show that the composition of the present invention has excellent moldability, the surface of the molded product is flat, and the compression set is good. Examples 5 to 8, Comparative Examples 3 and 4 Extrusion tests were conducted on compositions having the formulations in Table 3 in exactly the same manner as in Examples 1 to 3, except that 3 in Table 1 was used as the crosslinked vinyl chloride resin. As a comparative example, one using crosslinked vinyl chloride as shown in Table 1 2 is shown.

[Table] From these results, the composition of the present invention has good moldability and
It can be seen that the matte appearance is excellent. The high polymerization degree vinyl chloride resin is ethylene-vinyl chloride copolymer resin with a polymerization degree of 2800 (ethylene content approximately 2% by weight), and the low polymerization degree resin is ethylene-vinyl chloride copolymer resin with a polymerization degree of 430. The resin (ethylene content approximately 2% by weight) was prepared using dioctyl phthalate as plasticizer.

Claims (1)

[Claims] 1 (a) A polymer of vinyl chloride alone or a monomer mixture containing vinyl chloride as the main component, which meets JIS K
For 100 parts by weight of a highly polymerized vinyl chloride resin with an average degree of polymerization measured by the viscosity method of 6721 of 2000 or more, (b) vinyl chloride alone or a monomer mixture containing vinyl chloride as the main component and ethylenically unsaturated A cross-linked vinyl chloride resin 20 to 90, which is a copolymer of polyfunctional monomers having two or more of the following in the molecule, and contains 80% by weight or more of a gel content insoluble in tetrahydrofuran.
parts by weight, and (c) a polymer of vinyl chloride alone or a monomer mixture containing vinyl chloride as a main component,
The average degree of polymerization measured by the viscosity method of JIS K 6721 is
Low polymerization degree vinyl chloride resin of 500 or less 20 to 150
(d) 100 to 300 parts by weight of plasticity, and (e) additives if necessary.