JPS6140326A - Method of blending polyvinyl chloride with high polymer plasticizer - Google Patents

Abstract

PURPOSE:In kneading polyvinyl chloride with a high polymer plasticizer, to obtain a kneaded resin for medical uses, having improved transparency, free from ungelatinized particles even by the use of a blender having low kneading power such as an extruder, etc., by blending the polyvinyl chloride with the high polymer plasticizer dividedly, kneading them. CONSTITUTION:In kneading polyvinyl chloride with a high polymer plasticizer (ethylene vinyl acetate carbon monoxide copolymer having preferably >=10,000 mol.wt.), the polyvinyl chloride is blended with part of the high polymer plasticizer (preferably 10-40pts.wt. plasticizer based on 100pts.wt. polyvinyl chloride resin), kneaded, and the blend in blended with the rest of the plasticizer and kneaded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for kneading pellets containing polyvinyl chloride and a polymeric plasticizer and having no ungelled content.

[Conventional technology]

Vinyl chloride resin has excellent physical and mechanical properties, so it has many uses such as hard, semi-hard, and soft.

In order to obtain vinyl chloride resin molded products that are flexible and elastic at low to room temperatures, vinyl chloride resin is generally mixed with a plasticizer such as phthalate ester, trimellitate ester, or polyester. Above all, when trying to obtain a soft polyvinyl chloride composition with excellent oil resistance and extraction resistance, external plasticization using a polymer plasticizer with a molecular weight of 10,000 or more is recommended. It is desirable because it has superior oil resistance and extraction resistance compared to external plasticization using a chemical agent.

By the way, when such a polymer plasticizer is blended with polyvinyl chloride obtained by a normal suspension polymerization method, there is a problem that poor kneading occurs.

This is because polyvinyl chloride forms a film on the particle surface, and it is presumed that this film acts as a barrier and prevents absorption of the plasticizer, thereby deteriorating the gelation properties during kneading. This tendency is remarkable when a polymer plasticizer with a molecular weight of 10,000 or more is blended. When polyvinyl chloride with a small film, that is, vinyl chloride, is suspended polymerized in an aqueous medium, (a) polymerization is initiated in the presence of lipophilic sorbitan higher fatty acid ester and/or hydrophilic polyoxyethylene sorbitan higher fatty acid ester. (b) When the polymerization conversion rate reaches 5 to 40%, polyvinyl chloride produced by adding a water-soluble cellulose derivative can be produced by kneading it with a polymeric plasticizer having a molecular weight of 10,000 or more. , the gelling properties are improved (Japanese Patent Application Laid-Open No. 16864/1986)
No. 4) actually requires a strong mixing machine such as a Banbury mixer.

However, kneading with such a strong kneading machine causes severe thermal deterioration of the resin, causing the problem that the product becomes discolored.

Furthermore, if a kneading machine with a weak kneading capacity such as a two-roll machine or an extruder is used, the problem of coloring of the product can be solved, but in reality, there is a problem that a lump remains due to insufficient kneading.

As a method to improve this problem, we proposed a method in which a vinyl chloride copolymer is further added to polyvinyl chloride and a polymeric plasticizer and kneaded (Patent Application No. 59-076442.59-0
76443.59-076444).

Kneading by this method improves the gelation properties, but since the vinyl chloride copolymer itself has poor transparency, transparent formulations have the disadvantage of insufficient transparency, which limits the use of the copolymer. Further improvements were desired.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a method for kneading polyvinyl chloride and a polymer plasticizer that has excellent gelling properties and transparency.

[Means for solving problems]

The inventors of the present invention have conducted intensive research to obtain a vinyl chloride resin with excellent gelling properties and transparency even with weak kneading machines such as two rolls and extruders. When kneading, the present invention was completed based on the discovery that by dividing the polymer plasticizer into two or more times and kneading, gelling properties and transparency were surprisingly improved.

That is, in kneading polyvinyl chloride and a polymer plasticizer, the present invention includes adding a part of the polymer plasticizer and kneading, and then adding and kneading the remaining polymer plasticizer. This is a method of kneading polyvinyl chloride and a polymeric plasticizer, which are characterized by excellent gelling properties and transparency.

In the present invention, preferably in the first kneading, polyvinyl chloride 1
Pelletization is carried out by adding 5 to 50 parts by weight, preferably 10 to 40 parts by weight, of a polymer plasticizer to 00 parts by weight,
During the second or subsequent kneading, the remaining polymer plasticizer is added and kneaded.

The first addition amount of polymer plasticizer is polyvinyl chloride 100
If it is less than 5 parts by weight, the polymer plasticizer will be insufficient and kneading will be difficult to achieve, resulting in uneven kneading.
Even after kneading for the second time, uneven kneading remains, which is undesirable because it causes variations in the quality of production. Further, if the amount of the polymer plasticizer added is 50 parts by weight or more, the melt viscosity of the resin becomes too low and the stickiness in the polyvinyl chloride is not eliminated, which is not preferable.

To obtain a non-plastic resin by the kneading method of the present invention, for example, polyvinyl chloride, a stabilizer, a lubricant, a pigment, and a polymeric plasticizer are placed in a Henschel mixer and blended to obtain a powder. This powder is tied/knotted in an extruder, blended with the remaining polymer plasticizer using a Henschel mixer, and then pelletized in the extruder again, resulting in excellent gelling properties and transparency. A non-migrating resin is obtained.

If necessary, fillers, gelling promoters, ultraviolet absorbers, modifiers, etc. may be added. Further, there is no problem in adding a conventional plasticizer to the extent that the non-migration property is not impaired.

The polyvinyl chloride used in the present invention is a homopolymer of vinyl chloride, such as nrubitan higher fatty acid ester, polyoxyethylene sorbitan higher fatty acid ester, water-soluble cellulose derivative, polyvinyl alcohol, polyvinylpyrolidone, gelatin, etc. is used in combination as a dispersant, and as a catalyst, for example, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, diisopropyl peroxydicarbonate, di(2-ethylhexyl) haloxydicarbonate, tert-butyl peroxybivalate, etc. organic peroxide; 2,2'-azobisinbutyronitrile; 2.
2'-azobis-2,4-dimethylvaleronitrile, 2
, 2'-azobis-4-methoxy-2,4-dimethylvaleronitrile and the like are preferably used alone or in combination to polymerize vinyl chloride.

Examples of polymer plasticizers used in the present invention include polyester polymer plasticizers, ethylene-vinyl acetate-based polymer plasticizers, and polymer plasticizers made of ethylene-vinyl acetate-carbon oxide copolymers. Mention may be made of molecular plasticizers and modified products thereof. In addition, from the viewpoint of problems such as bleeding, a molecular weight of 10.000 or more is desirable. Among these, a polymeric plasticizer having a molecular weight of 10,000 or more and consisting of a copolymer of ethylene/vinyl acetate/carbon oxide is particularly effective in obtaining a polyvinyl chloride composition having oil resistance and extraction resistance.

In the present invention, the object is achieved by first kneading a portion of the polymeric plasticizer with polyvinyl chloride and then kneading it again with the remaining polymeric plasticizer. Note that the remaining polymer plasticizer may be further divided and kneaded.

When carrying out the present invention, a kneading machine with a weak kneading capacity, such as a two-roll machine or an extruder, is used, but in consideration of productivity, workability, etc., it is preferable to employ an extruder.

As the extruder, single-screw, twin-screw, multi-screw, or conical types may be used alone or in combination of two or more.

The resin kneaded in the present invention is molded by known methods such as calendering, melt extrusion, and stamp injection, and then put into practical use.

The resin kneaded in the present invention has a smooth surface when molded because it has few ungelled particles, and has excellent transparency, so it is suitable for use in medical, industrial, and food applications. .

〔Example〕

The present invention will be explained below with reference to Examples.

Example-1 Polyvinyl chloride (
PVC) 15 to 9, stabilizer, 125 to 9, lubricant 0.3
9 was added to 45 and blended at high speed for 10 minutes.

Then, 6 kg of polymer plasticizer 11 Elvaloy 74211 (trademark) was added and blended with stirring, and after 3 minutes, it was discharged and the PVC
/ Elvaloy 742 blend was obtained.

This blend was kneaded and pelletized using a twin-screw extrusion machine Ikegai GT-110 under the conditions shown in Table 1.

In addition to this beret 11 Elvaloy 742” 6k
g, stirred for 3 minutes with a Henschel mixer, and
The mixture was kneaded and pelletized under the second conditions shown in the table.

This pellet was pressed at 180℃ to a thickness of 0.5111
A transparent sheet was obtained, and its transparency was visually inspected, and it was found that both properties were good.

Example-2 In addition to the pellet obtained in Example-1, 11 Elvaloy 742
6k!9 was placed in a Henschel mixer, stirred for 3 minutes at °C, and kneaded under the second conditions of Example 1 to form pellets. The pressed sheet of the pellets had good clarity and transparency.

Example 3 Kneading and pelletization were carried out in the same manner as in Example 1, except that the amount of '1 Elvaloy 742'' used was changed to 3 kg in the first time and 9 kg in the second time.

The press sheet of this pellet was good in both visibility and transparency.

Comparative Example-1 A blend was obtained in the same manner as in Example-1, except that the amount of Elvaloy 742'' was added at once, and the mixture was processed using a twin-screw extruder under the conditions shown in Table 1. The mixture was kneaded and made into pellets.The pressed sheet of the pellets had many lumps and poor transparency.

〔Effect of the invention〕

Since the present invention has the above-mentioned structure, the generation of lumps due to poor kneading, which has been a problem in the past, is prevented, and it is particularly useful for soft vinyl chloride resin molded products using transparent grade polymer plasticizers.

I had a high face all day.

Claims (1)

[Claims] 1. A gel characterized in that when kneading polyvinyl chloride and a polymer plasticizer, a part of the polymer plasticizer is added and kneaded, and then the remaining polymer plasticizer is added and kneaded. A method for kneading polyvinyl chloride and a polymer plasticizer with excellent chemical properties and transparency.