JPH02300252A - Vinyl chloride resin composition for molding - Google Patents

Abstract

PURPOSE:To improve both tension and elongation in a molten state and to obtain a corrugated pipe for wiring for electric power and telecommunication fields without fluctuation in strength by blow molding, by incorporating a melt tension improver in a vinyl chloride resin with a high degree of polymn. CONSTITUTION:A vinyl chloride resin compsn. for blow molding is provided by compounding 100 pts.wt. vinyl chloride resin with a high degree of polymn. (an average degree of polymn. of 900 or higher, most desirably 900-1,300) with 0.5-3 pts. molt tension improver (e.g. a methyl methacrylate polymer) and if necessary, 1-3 pts. auxiliary for improving impact strength (e.g. phthalates).

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vinyl chloride resin composition for molding,
In detail, the tension and elongation rate during heating and melting are high,
In particular, the present invention relates to a vinyl chloride resin composition with a high degree of polymerization that exhibits flow characteristics suitable for molding corrugated pipes in a molten state.

[Prior Art] Vinyl chloride resins have been widely put into practical use as materials for various commercial bottles, containers for alcohol and oils, etc., and blow molding is used to manufacture these containers. The most common vinyl chloride resin composition used as material for these containers is mainly polyvinyl chloride with a degree of polymerization of about 700 to 800. I! ! In addition to containing a small amount of MBS (methyl methacrylate-butadiene-styrene copolymer) as a strength-improving component, it also contains small amounts of tin-based stabilizers, melt viscosity modifiers, lubricants, etc., and improves blow moldability and the physical properties of product containers. I am also somewhat satisfied with this.

Recently, there have also been attempts to use vinyl chloride resin as a molding material for corrugated pipes for power communication wiring, etc., and to manufacture corrugated pipes by a combination of extrusion technology and blow molding technology.

However, when attempting to continuously blow mold corrugated pipes using vinyl chloride resin, various problems arise as shown below. For example, corrugated pipes for power communication wiring require a higher level of durability and strength than ordinary containers, so polyvinyl chloride with a high degree of polymerization (p
= about 900 or more), and such highly polymerized materials have high melt viscosity and low elongation in the molten state, making blow molding very difficult. Therefore, as a means to improve blow moldability, it may be possible to lower the melt viscosity by increasing the blending amount of a melt viscosity modifier, but this would not only cause the resin composition to become cylindrical, but also reduce its strength. , the melt tension of the composition decreases, the uniformity of material elongation during blow molding deteriorates, and the thickness of the blow molded product becomes non-uniform, resulting in uneven strength. In other words, there is an inverse relationship between the viscosity of a molten vinyl chloride resin composition (i.e., the ease of elongation during blow molding) and the resin tension, and this is a factor that deteriorates blow moldability and causes strength unevenness in molded products. It has become. When a vinyl chloride resin composition with a high degree of polymerization and high viscosity is used, the above-mentioned tendency becomes conspicuous in the form of difficulty in blow molding.

[Problems to be Solved by the Invention] The present invention has been made focusing on the above-mentioned circumstances, and its purpose is to improve both the tension and elongation during melting, and to increase the strength by blow molding etc. The object of the present invention is to provide a vinyl chloride resin composition with a high degree of polymerization that allows molded articles with uniform and excellent physical properties to be obtained.

[Means for Solving the Problems] The composition of the present invention that can solve the above problems is a resin composition for molding whose main component is a vinyl chloride resin having an average degree of polymerization of 900 or more. The gist is that 0.5 to 3 parts by weight of a melt tension improver is blended with 100 parts by weight of a vinyl chloride resin, or 1 to 3 parts by weight of an impact strength improving aid is blended together with this. It is.

[Function] The melt tension improver blended into the vinyl chloride resin composition for molding in the present invention has a unique action and effect compared to general-purpose additives such as plasticizers. When blended in an appropriate amount with a resin, it has the effect of increasing the melt tension and elongation of the resin, making it extremely suitable for blow molding and the like.

That is, in conventional vinyl chloride resin compositions, as mentioned above, elongation at melting and tension at melting are in a reciprocal proportional relationship, and it was not possible to satisfy both at the same time. However, when an appropriate amount of a melt tension improver is added, Both of the above two required properties have been improved, and the elongation of the molten resin has become better, making it easier to mold along the molding surface of the blow molding mold, as well as improving the uniformity of elongation of the material due to the improved melt tension. This allows blow molding to proceed extremely smoothly.

Furthermore, the elongation at melting and the tension at melting mentioned above are extremely important characteristics not only for blow molding but also for extrusion molding, pressure molding, etc., so the present invention is effective for molding processes other than blow molding. It can be used for

Figure 1.2 shows the expansion rate during blow molding when a polymethyl methacrylate melt tension improver was added to the vinyl chloride resin composition having the basic composition shown below, and when it was not added. Relationship of melt tension (Figure 1),
Figure 2 shows the relationship between resin temperature and elongation rate.By adding a melt tension improver, the melt tension (melt strength) relative to the expansion rate during blow molding can be improved by about 20 to 50%. Also, the elongation rate at m melting is 3
It has improved by about 50%.

(Resin composition) Polyvinyl chloride (r=1000) 100 parts by weight MBS
- 4 parts by weight tin stabilizer (dimethyltin mercaptide) 2I! Parts by weight Metal soap (calcium/magnesium stearate) 1.5 Parts by weight Lubricant (liethylene wax) 0.5 parts Impact strength improving aid (fatty acid ester) 2.0! Amount of stimulant melt tension improver 0 or 2.0! (Measurement method) As shown in FIG. The resin discharged from the machine is forcibly taken up and the tension at that time is measured by the load detector 4. The taking speed is increased in stages and the speed and tension when the discharged resin is cut are measured. The faster the cutting speed, the easier the resin stretches, and the higher the tension, the stronger the melt strength, and the easier it is to obtain uniform elongation.

Extruder: Different direction parallel type twin screw extruder (inner diameter 20ml) Screw: Full flight type, L/D-27 rotation speed 17
~18 rpm Die: 3fflφX22mL, Strand die setting temperature (℃) (r C2C3 die discharge rate: 1B, 1~16.5g/min Take-up condition: Increase the speed step by step at in/min intervals from a speed of 2m/min , take off for 5 minutes at each speed and repeat until the strand breaks.

Between nozzle and load cell 11t: 222.5a+i
The reason why the melt tension and melt elongation of vinyl chloride resin compositions are improved by the addition of a melt tension improver is not necessarily clear, but the melt tension improver It is thought that this increases the degree of entanglement (between polyvinyl chloride molecules) and increases the tension and elongation rate in the molten state.

The effect of such a melt tension improver is that vinyl chloride resin 1
00! It is effectively exhibited by containing it in an amount of 0.5 to 3 parts by weight. If it is less than 0.5 parts by weight, the above-mentioned improvement effect will hardly be exhibited, while if it exceeds 3 parts by weight, the heat distortion temperature will decrease, the impact resistance properties will decrease,
The material is sensitive to heat and easily breaks. The most common melt tension improver is a homopolymer or copolymer of acrylic ester or methacrylic ester (polymerization degree is about 20 to several million million), but in addition, small amounts of acrylamide, acrylonitrile, etc. may be copolymerized, or further may be copolymerized with a small amount of a vinyl compound, a styrene compound, or the like.

As mentioned above, one feature of the present invention is that a specific amount of a melt tension improver is blended into the vinyl chloride resin composition, but in addition to this, when an appropriate amount of an impact strength improver is included,
Plasticization of the vinyl chloride resin composition progresses, making it possible to further improve the impact resistance of the product. That is, as impact strength improving aids, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, di-n-octyl phthalate, di-
Phthalic acid esters such as isooctyl phthalate, diisodecyl phthalate, butylbenzyl phthalate, di-2-ethylhexyl adipate, di-2-ethylhexyl azelate.

Aliphatic dibasic acid esters such as di-2-ethylhexyl sebacate; tricresyl phosphate.

Phosphate esters such as trixylenyl phosphate, 2-ethylhexyldiphenyl phosphate, trimethyl phosphate, triphenyl phosphate; epoxidized vegetable oil; polyester plasticizer: nitrile synthetic rubber, etc. are used, but these are salt hibinyl resins. It penetrates into the inside of the resin and increases the fluidity (smoothness) of the resin and plasticizes it, and also improves the dispersibility of impact strength improvers such as MBS, which are separately blended, into the vinyl chloride resin, improving the final molded product. Demonstrates the effect of further increasing impact resistance. The preferred blending amount of the impact strength improving aid that exhibits these effects is in the range of 1 to 3 parts by weight per 100 parts by weight of the vinyl chloride resin, and if it is less than 1 part by weight, the impact strength improving effect will not be effectively exhibited. On the other hand, if the amount exceeds 31 parts, the entire resin composition becomes too plasticized, resulting in insufficient strength.

In addition, in the present invention, various compounding agents can be used for the purpose of improving the moldability of the composition and the physical properties of the molded article, and these will be briefly explained below.

1. Tsuji 2. First of all, polyvinyl chloride is a typical base vinyl chloride resin, but in addition, small amounts of copolymerized vinyl acetate, vinylidene chloride, acrylic esters, methacrylic esters, styrene, etc. A vinyl chloride copolymer copolymerized with a polyvinyl chloride can also be used. The preferred molecular weight of these vinyl chloride resins is appropriately selected depending on the properties required of the molded product, but the effects of the present invention are most effectively exhibited when the average degree of polymerization CP) is in the range of 900 to 1300. belongs to.

MBS Methyl methacrylate-butadiene is useful as a component for increasing the impact resistance of vinyl chloride resin molded products, and has a resistance of 3.
The effect can be effectively exhibited by adding up to 10 parts by weight.

It is formulated to suppress the dehydrochloric acid reaction that occurs when vinyl chloride resin is exposed to heat or light for a long time, and contains white lead, tribasic lead sulfate, dibasic lead phosphite, Lead salt stabilizers such as dibasic lead phthalate, tribasic lead maleate, lead silicate and their silica gel coprecipitates: lead, cadmium, barium, zinc, calcium, etc. and stearic acid, ricinoleic acid, naphthenic acid, Metal soap stabilizers such as 2-ethylhexoic acid; organotin stabilizers such as dibutyltin dilaurate, dibutyltin maleate, and dibutyltin mercaptide; triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, Examples include organic stabilizing aids such as trinonylphenyl phosphite; ultraviolet absorbers such as salicylic acid esters, hydroxybenzophenones, and benzotriazoles, and these may be used in combination of 2 f1 or more if necessary. The preferred blending amount is between 1 and 5 parts by weight per 100 parts by weight of the vinyl chloride resin.

In addition to increasing the fluidity of the molten resin and improving its moldability, it also has the effect of increasing the surface smoothness of the molded product while preventing it from sticking to the molding die and improving its releasability.Higher fatty acids and their derivatives, Examples include the aforementioned metal soaps that also serve as stabilizers, natural or synthetic waxes, etc., and the preferred blending amount is about 411 parts of O, S to 100 parts by weight of vinyl chloride resin. l Mainly has the effect of increasing the hardness, modulus, and bending rigidity of the molded body, and examples thereof include calcium carbonate, kaolin, clay, silica, diatomaceous earth, and carbon black.

As compounding agents other than those mentioned above, colorants, flame retardants, antistatic agents, foaming agents, fungicides, etc. may be used as necessary.

[Example] Molding vinyl chloride resin compositions having the component compositions shown in Table 1 were prepared, and the melt tension and take-off speed at break were examined for each according to the method shown in FIG. The results are summarized in Table 1.

From Table 1, it can be considered as follows.

Experiment Nos. 1.2, 3, and 4.8 are examples that meet the specified requirements of the present invention, and show high values for both melt tension and take-off speed at break, and have very good formability. I can see that it is something.

On the other hand, Experiment No. 5.6.7 is a comparative example that lacks the specified requirements of the present invention, and has the following problems in physical properties.

Experiment No. 5: This is a comparative example in which there is too much melt tension improver, resulting in a decrease in Charpy impact strength and insufficient impact resistance of the product.

Experiment No. 6: This is a comparative example in which the melt tension improver is insufficient, and the melt tension is poorer than that of the example, and it is clear that there will be a problem in uniformity during blow molding. The molding rate is also low, and there are likely to be restrictions on the conditions during blow molding.

Experiment No. 7: Impact-electrical direction 1., N, tl'+Ij
This is a comparative example with too much iM dyeing, and not only the melt tension is low, but also the tensile strength of the molded product is low, and the characteristics of using a high polymerization degree vinyl chloride resin are not effectively exhibited.

[Effects of the Invention] The vinyl chloride resin composition for molding of the present invention is constructed as described above, and as described above, this composition can be improved in tension and elongation during melting by adding an appropriate amount of a melt tension improver. As both properties have been improved, the elongation of the resin material is particularly good during molding, and its uniformity is also excellent.It spreads to every corner of the inner surface of the mold without causing thickness unevenness, and has uniform physical properties. Excellent molded products can be obtained. In particular, when applied to continuous blow molding of wiring corrugated pipes for electric power communications, etc., the excellent fluidity properties (tension and elongation) of the resin composition in the molten state are fully exhibited, and the physical properties and homogeneity of the product are improved. and productivity. Furthermore, since the impact resistance can be further increased by adding an impact strength improving agent, impact fracture during use can be suppressed, and highly reliable molded products can be obtained.

[Brief explanation of drawings]

Figure 1 shows the relationship between expansion rate and resin melt tension during blow molding, and Figure 2 shows the relationship between resin temperature and elongation during melting.
A graph showing a comparison between the resin composition of the present invention and a comparative composition,
FIG. 3 is an explanatory diagram showing a method for measuring physical properties.

Claims (2)

[Claims] (1) In a resin composition for molding mainly composed of a high polymerization degree vinyl chloride resin with an average degree of polymerization of 900 or more, 0.5 to 3 parts by weight of the resin is melted per 100 parts by weight of the vinyl chloride resin. A vinyl chloride resin composition for molding processing, characterized in that it contains a tension improver. (2) In a resin composition for molding whose main component is a high polymerization degree vinyl chloride resin with an average degree of polymerization of 900 or more, 0.5 to 3 parts by weight of the melted vinyl chloride resin is added to 100 parts by weight of the vinyl chloride resin. A vinyl chloride resin composition for molding, characterized in that it contains a tension improver and 1 to 3 parts by weight of an impact strength improving aid.