JPS595607B2 - Method for producing transparent and flexible synthetic resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing transparent and flexible resin.

There are few resins that are flexible and transparent.

Vinyl chloride resin is one of these few resins. However, vinyl chloride resins exhibit sufficient flexibility only when a plasticizer is added, and they do not exhibit sufficient flexibility unless a plasticizer is added. However, when plasticizing is added, the plasticizer oozes out onto the resin surface and adheres to objects it comes in contact with.
This may cause problems such as the surfaces of the molded bodies sticking together. In particular, some of the plasticizers that leach out are harmful. Therefore,
It has been desired to develop a transparent and flexible resin free from defects such as surface oozing and surface adhesion. To meet this demand, attempts have been made to copolymerize vinyl chloride with other monomers, or to graft-polymerize vinyl chloride with other polymers or copolymers.

One of the methods was to graft-polymerize vinyl chloride onto an ethylene/vinyl acetate copolymer. However, through such attempts, the graft polymers obtained so far have been found to be unsuitable for this purpose because, although they are flexible, they have poor transparency. Additionally, in order to meet the above-mentioned demands, attempts have been made to add a polymeric plasticizer with low migration properties to vinyl chloride polymers.

As one of these, a terpolymer consisting of ethylene, vinyl acetate, and carbon monoxide was used as a polymer plasticizer, and this was mixed with a vinyl chloride resin. However, although the composition obtained by this method has good transparency, it has poor thermal stability and poor gelling properties, so it cannot meet the above objectives. Ta. The inventor has discovered that a polymer meeting the above requirements can be produced by graft polymerizing vinyl chloride to a terpolymer of ethylene, vinyl acetate, and carbon monoxide.

However, the inventor found that a polymer obtained by graft-polymerizing only vinyl chloride onto a terpolymer still lacks flexibility depending on the application.Thus, as a result of further research, the inventor found that When the original copolymer is graft-polymerized with vinyl chloride and other monomers at a certain ratio, the resulting graft polymer is the same as that obtained by graft-polymerizing only vinyl chloride onto the terpolymer. It is more flexible than
It was found that other properties were also not inferior. In other words, the polymer obtained by graft polymerizing vinyl chloride and other monomers onto a terpolymer exhibits sufficient flexibility without the addition of a plasticizer, is transparent, and is heat resistant. It was found that the stability and gelation properties were also good. This invention was made based on such knowledge. This invention is
Vinyl chloride is added in a proportion of 20 to 300 parts by weight to 100 parts by weight of a copolymer consisting of 50 to 70 parts of ethylene, 20 to 40 parts of vinyl acetate, and 5 to 20 parts of carbon monoxide, and copolymerized with vinyl chloride. The present invention relates to a method for producing a transparent and flexible synthetic resin, which comprises graft polymerizing 2 to 100 parts by weight of another polymerizable monomer.

The resin obtained by this invention (hereinafter referred to as the graft polymer of this invention) is one of the few resins in that it is flexible and transparent even without the addition of a plasticizer.

In terms of transparency and flexibility, the graft polymer of the present invention is almost as good as a composition obtained by adding a vinyl chloride resin to the above-mentioned copolymer of ethylene, vinyl acetate, and carbon monoxide. Although they have similar characteristics, they are superior in terms of thermal stability and ease of processing. In particular, since the graft polymer of the present invention is obtained as a uniform composition from the beginning, it is natural that it is easier to process than the composition obtained by mixing two types of polymers as described above. be. Thus, the graft polymer of the present invention has both flexibility and transparency, as well as good thermal stability and processability. This resin is unique in that it exhibits neither plasticizer leaching nor surface tackiness. The method of this invention is characterized in that vinyl chloride and other monomers are simultaneously graft-polymerized to a specific terpolymer at a constant ratio.

In that case, the terpolymer consists of 50 to 70 parts by weight of ethylene, 20 to 40 parts of vinyl acetate, and 5 to 20 parts of carbon monoxide. Hereinafter, this copolymer will be referred to as a terpolymer, and the terpolymer is already known as described in JP-A-48-26228. Additionally, some of these terpolymers are commercially available. In the method of this invention, this commercially available copolymer can be used as is. In order to carry out the method of the present invention, a mixture of vinyl chloride and other monomers may be graft-polymerized onto the terpolymer in a fixed ratio according to a known method.

As the polymerization method, a suspension polymerization method or an emulsion polymerization method can be used. A specific method for graft polymerizing vinyl chloride onto the terpolymer is as follows.

After adding water, a dispersant, and a terpolymer to an autoclave equipped with a stirrer, vacuum suction is applied to remove oxygen present in the autoclave. Next, vinyl chloride and other monomers copolymerizable with vinyl chloride are added with stirring, and the terpolymer is dissolved in the monomer mixture over a period of 0.5 to 3 hours. Thereafter, a polymerization initiator is added, and the temperature is raised while stirring is continued. The temperature inside the autoclave is 50 to 80℃.
and maintain this temperature for 5 to 15 hours.
During this time, the monomer mixture is graft-polymerized onto the terpolymer as a backbone to form a graft polymer.
In order to help disperse the monomer mixture in which the terpolymer is dissolved, partially saponified polyvinyl alcohols, methylcellulose, hydroxymethylcellulose,
Cellulose derivatives such as carboxymethylcellulose, polyvinylpyrrolidone and other surfactants can be used. The type of polymerization initiator to be added differs depending on whether suspension polymerization or emulsion polymerization is performed. To perform suspension polymerization, organic peroxides such as benzoyl peroxide, lauroyl peroxide, di-2-ethylhexyl peroxydicarbonate, etc. are used. Moreover, ammonium persulfate, potassium persulfate, etc. are used to perform emulsion polymerization. These polymerization initiators are used in an amount of 0.02 to 0.3% by weight based on the total amount of vinyl chloride and other monomers. The total amount of the terpolymer, vinyl chloride, and other monomers used during polymerization and the weight ratio of the aqueous medium are:
A ratio of 1:1, 2 or 1:3 is chosen. Other monomers that can be copolymerized with vinyl chloride include vinyl esters such as vinyl acetate and vinyl stearate, olefins such as ethylene and propylene, and vinyl ethers such as ethyl vinyl ether, n-propyl vinyl ether, and 2-ethylhexyl vinyl ether. , ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate, and maleic esters such as dibutyl maleate and di-(2-ethylhexino) maleate.

Among these, preferred monomers are olefins other than vinyl esters, vinyl ethers, acrylic esters, and maleic esters. This preferred monomer can be said to be one whose homopolymer glass transition point is −20° C. or lower when it is polymerized to form a homopolymer. Vinyl chloride and the other monomers mentioned above are 20 to 300 parts by weight of vinyl chloride and 2 parts by weight of other monomers based on 100 parts by weight of the terpolymer.
These monomers are added in slight excess so as to graft polymerize by 100 parts by weight.

It is already known that when adding monomers, if there is a large difference in the copolymerizability ratio between vinyl chloride and other monomers, it is necessary to Be careful not to add larger monomers later so that only one monomer polymerizes, leaving the other monomers behind. The end point of polymerization is
This is estimated and determined from the relational expression between the internal pressure of the polymerization vessel and the grafting amount of the monomer mixture, which was obtained in advance through experiments.

After the polymerization is completed, unreacted monomers are removed, and then the suspension or emulsion in the autoclave is filtered to remove water to obtain polymer particles.

Next, the polymer particles are washed with water and dried to form a product. In the method of this invention, the terpolymer is limited to a terpolymer containing 50 to 70 parts of ethylene, 20 to 40 parts of vinyl acetate, and 5 to 20 parts of carbon monoxide by weight. This is because such a composition is suitable for making the obtained graft polymer transparent and flexible. In addition, the reason why the ratio of vinyl chloride to be graft-polymerized to this terpolymer was set to 20 to 300 parts by weight to 100 parts by weight of the former is that vinyl chloride is 20 to 300 parts by weight.
If the amount is less than 300 parts by weight, the resulting graft polymer will have poor properties as a vinyl chloride polymer and will be unsatisfactory.On the other hand, if the amount exceeds 300 parts by weight, the resulting graft polymer will have poor flexibility. This is because it becomes lacking in sexuality and cannot be completely satisfying. Furthermore, the reason why the amount of other monomers is limited to 2 to 100 parts by weight with respect to 100 parts by weight of the terpolymer is that if the amount of other monomers is less than 2 parts by weight, the resulting graft polymer will not have sufficient flexibility. On the other hand, if it exceeds 100 parts by weight, the resulting graft polymer will lose its excellent properties as a vinyl chloride polymer. Among these, particularly preferred is 50 to 150 parts by weight of vinyl chloride per 100 parts by weight of the terpolymer;
This is a polymer obtained by graft polymerization with 20 to 100 parts by weight of another monomer having a homopolymer glass transition point of -20° C. or lower.

The method of this invention is excellent in that a transparent and flexible synthetic resin can be obtained.

That is, the resin is made without adding plasticizer to it.
When this is kneaded while heating, it becomes a resin that can be easily molded without causing thermal decomposition. This resin can be easily formed into a desired molded product by various molding methods such as extrusion molding, injection molding, and calendar molding. The molded product thus obtained is a very unique resin in that it is flexible and transparent even without the addition of a plasticizer. Moreover, since this molded article does not contain a plasticizer, the plasticizer does not migrate or ooze out, so it has the advantage that it can be safely used in areas that come into contact with food or the human body. Next, the characteristics of the graft polymer according to the present invention will be explained in more detail with reference to Examples and Comparative Examples.

However, in the following Examples and Comparative Examples, parts simply represent parts by weight. Example 1 100 parts of a terpolymer consisting of 64 parts of ethylene, 24 parts of vinyl acetate, and 12 parts of carbon monoxide, 500 parts of water, and 3 parts of partially saponified polyvinyl alcohol were placed in an autoclave equipped with a stirrer, and degassed under reduced pressure. Later, 120 parts of vinyl chloride,
25 parts of ethylene was charged.

Thereafter, the temperature was raised to 64° C., and after stirring for 1 hour, 0.1 part of lauroyl peroxide was added to initiate polymerization.
Polymerization was stopped 7 hours after the start of polymerization, and unreacted vinyl chloride and ethylene were recovered, followed by filtering, washing with water, and drying to obtain graft polymer particles. When this graft polymer particle was analyzed, it was found that the weight of vinyl chloride was 46? , 4% by weight of ethylene, and 50% by weight of the terpolymer were graft polymerized.

When we measured the transparency and flexibility of these particles, we found that
The results are shown in Table 1 below, and all were found to be excellent. Note that transparency and flexibility were measured by the following methods. Transparency: Add 2 parts of TUS#1400 (dibutyltin mercapto stabilizer manufactured by Nitto Kasei Co., Ltd.) as a stabilizer to 100 parts of the graft polymer, and knead with a roll.
Thickness 0.5W! A 1 sheet was prepared, and its transparency was measured with the naked eye.

Flexibility: A sheet made with the above formulation is pressed to a thickness of 1.
0m7! The flexibility temperature of this board was measured using the Kratschberg Softness Temperature Measurement Method.

In addition, flexibility was separately measured by measuring shore hardness at 20°C and 0°C. Example 2 As a terpolymer, 55 parts of ethylene, 32 parts of vinyl acetate
parts, 100 parts of a copolymer consisting of 13 parts of carbon monoxide, 5 parts of water.
00 parts and 0.4 parts of partially saponified polyvinyl alcohol were placed in an autoclave equipped with a stirrer, and degassed under reduced pressure.
120 parts of vinyl chloride was charged.

Thereafter, the temperature was raised to 64°C, and after stirring for 1 hour, 0.1 part of lauroyl peroxide and 5 parts of 2-ethylhexyl acrylate were added to initiate polymerization. During 5 hours after the start of polymerization, 25 parts of 2-ethylhexyl acrylate was successively added to advance the polymerization. The polymerization was stopped 6 hours after the start of polymerization, and unreacted vinyl chloride and 2-ethylhexyl acrylate were recovered, followed by filtering, washing with water, and drying.
Graft polymer particles were obtained. Analysis of the graft polymer particles revealed that vinyl chloride was 38% by weight and 2% by weight.
Ethylhexyl acrylate - 2% by weight, terpolymer 5
Graft polymerization was carried out at a ratio of 0% by weight.

When the transparency and flexibility of the particles were measured, the results were as shown in Table 1 below, and both were found to be excellent. Comparative Example 1 In this comparative example, 100 parts of a binary copolymer containing no carbon monoxide, that is, a binary copolymer of 72 parts of ethylene and 28 parts of vinyl acetate, was used instead of the terpolymer. A graft polymer was obtained by carrying out polymerization in exactly the same manner as in Example 1 except for using the following.

This graft polymer contains 46 parts of vinyl chloride and 4 parts of ethylene.
50 parts of the binary copolymer.

When the transparency and flexibility of this graft polymer were measured by the method described in Example 1, the sheet obtained from the polymer had a milky white color, which did not meet the purpose in terms of transparency. . Comparative Example 2 In this comparative example, the amount of vinyl chloride was 80 parts by weight, and 2
- except that ethylhexyl acrylate was not used.
Polymerization was carried out in exactly the same manner as in Example 2 to obtain graft polymer particles.

Claims (1)

[Claims] 1 50 to 70 parts by weight of ethylene, 20 parts of vinyl acetate
20 to 30 parts of vinyl chloride to 100 parts by weight of a copolymer consisting of 5 to 20 parts of carbon monoxide and 5 to 20 parts of carbon monoxide
A method for producing a transparent and flexible synthetic resin, which comprises graft polymerizing 0 part by weight of another monomer copolymerizable with vinyl chloride and 2 to 100 parts by weight.