JPS61296009A - Production of liquid prepolymer - Google Patents

Abstract

PURPOSE:To obtain the titled prepolymer, preservable at room temperature for a long period and having a low viscosity without coloring, by polymerizing an unsaturated monomer consisting essentially of a specific compound in a solvent of an ester. CONSTITUTION:(A) 100pts.wt. unsaturated monomer obtained by incorporating (i) an alkylene glycol bis(allyl carbonate) as a principal component with (ii) <=50mol% copolymerizable unsaturated monomer, e.g. vinyl acetate, is mixed with (B) preferably 10-2,000pts.wt. polymerization solvent of an ester, e.g. methyl acetate, and, e.g. a radical polymerization initiator such as benzoyl peroxide, is added thereto to give a saturated conversion at 50-150 deg.C. The solvent is then removed by distilling away or washing with water to afford the aimed prepolymer.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a method for producing an unsaturated liquid prepolymer containing alkylene glycol bis(allyl carbonate) as a main component. The present invention relates to a method for producing a liquid prepolymer that can be stored at room temperature for a long period of time without worrying about.

[Conventional technology]

Alkylene glycol bis(allyl carbonate), typified by diethylene glycol bis(allyl carbonate), is used as a monomer for transparent plastics. Polymers with excellent optical and mechanical performance can be obtained by polymerization, and are particularly useful for organic glasses (lenses). ) is widely used as Moreover, these alkylene glycol bis(allyl carbonate) polymer molded products are generally produced by a cast polymerization method after adding a radical initiator to the corresponding hexamer. However, when attempting to obtain a polymer molded article having sufficient hardness for practical use, these alkylene glycol bis(allyl carbonate) monomers cause large polymerization shrinkage during polymerization. For example, diethylene glycol bis(allyl carbonate) undergoes as much as about 14% shrinkage during polymerization. Therefore, it is difficult to obtain sufficient molding precision in cast polymerization, which is a common polymerization method for alkylene glycol bis(allyl carbonate).

For this reason, several methods have been proposed to reduce the vertical shrinkage rate of alkylene glycol bis(allyl carbonate). For example, there is a method of producing a liquid prepolymer by adding a small amount of a radical initiator to diethylene glycol bis(allyl carbonate) and then polymerizing it by heating. However, in this case, the three-dimensional crosslinking reaction proceeds and gelation occurs when the monomer polymerization rate reaches about 17%, so that the shrinkage rate during polymerization can only be improved to about 12%.

[Problem that the invention seeks to solve]

For this reason, the present inventors added a small amount of radical initiator to alkylene glycol bis(allyl carbonate) in a specified solvent such as benzene or toluene, and by distilling off the solvent during heating polymerization, We have already proposed a method to obtain a prepolymer with improved shrinkage during polymerization. (Patent Application II@59-186473). That is, according to this method, gelation does not occur even when the polymerization rate of the unsaturated monomer is 17% or more, and a low-viscosity liquid prepolymer can be produced. However, the alkylene glycol bis(allyl carbonate) resin obtained by molding this liquid prepolymer has a yellow coloration.
There is a problem in that the excellent optical properties of colorless and transparent properties of alkylene glycol bisallyl carbonate (alkylene glycol bisallyl carbonate) resins are impaired. This is presumed to be because the benzene, toluene, etc. used as the solvent undergoes oxidation and substitution reactions by the radical initiator and remains in the prepolymer, causing the prepolymer to be colored yellow.

[Means to solve the problem]

Therefore, the present inventors have solved the above-mentioned coloring problem while reducing the large polymerization shrinkage rate, which is a drawback of resins whose main component is alkylene glycol bis(allyl carbonate) (hereinafter abbreviated as AGAC). As a result of further research, we discovered that the desired objective could be achieved by polymerizing an unsaturated monomer mainly composed of ACAC in an ester solvent and removing the solvent. This invention led to the provision of the invention. That is, according to the present invention, when producing a prepolymer, an unsaturated upper
Even if the polymerization rate exceeds 17%, the three-dimensional crosslinking reaction does not proceed, there is no risk of gelation, and the product has the desired polymerization rate and is a colorless and transparent liquid with low viscosity and no yellow coloring. A prepolymer can be produced, which can be stored at room temperature for a long period of time, and by further polymerizing the prepolymer, an excellent colorless and transparent polymer can be obtained.

Examples of AGAC used in the present invention include ethylene glycol bis(allyl carbonate), diethylene glycol bis(allyl carbonate), triethylene glycol bis(allyl carbonate), propylene glycol bis(allyl carbonate), and dipropylene glycol bis(allyl carbonate). allyl carbonate).

These include polyoxyalkylene polyol bis(allyl carbonate).

Further, it is also possible to use an unsaturated monomer copolymerizable with A, OA, and C as described above, generally within a range of 50 mol % or less, which does not impair the desirable physical properties of the AGAC. Such a combination of 1 ((combinable unsaturated upper and lower
The final target AGA (") is selected as appropriate depending on the polymer molded article, and is used to impart various improved properties such as a high refractive index, excellent mechanical properties, or to reduce the polymerization rate when obtaining the polymer. In order to obtain AGAC polymer moldings (lenses) with a particularly high refractive index, copolymerizable unsaturated monomers with a homopolymer refractive index of 15 or more are used6). The copolymerizable unsaturated monomers preferably used in the present invention generally include vinyl compounds, allyl compounds, etc. Typical examples include vinyl acetate, #A vinyl, vinyl alcohol, and styrene. Vinyl compounds such as , chlorstyrene, methylstyrene; methyl methacrylate, methyl acrylate, ethylene glycol dimethacrylate.

Ethylene glycol bisglycidyl methacrylate, 2
-Hydroxyethyl methacrylate, phenyl methacrylate, bisphenol A dimethacrylate), 2.2-
Methacrylic acid esters and acrylic acid esters such as bis(4-methacryloxyethoxyphenyl)propane, dichlorosulphthalate, diallyl terephthalate, diallyl isophthalate, diallyl tartrate, diallyl epoxysuccinate, diallyl maleate, trilyl isocyanurate .

Examples include allyl compounds such as allyl salicylate and allyl phenyl carbamate.

In the present invention, selective use of polymerization solvents, particularly esters, is extremely important in order to obtain the desired desired liquid prepolymer. Incidentally, when aromatic hydrocarbons such as toluene and benzene are used instead of esters, the obtained prepolymer is colored yellow, which is not preferable. Representative examples of esters preferably used in the present invention include fatty acids such as methyl acetate, ethyl acetate, propyl acetate, phenyl acetate, ethyl formate, ethyl propionate, ethyl butyrate, ethyl valerate, and methyl malonate. Aromatic carboxylic acid esters such as methyl benzoate; Lactones such as γ-lactone and δ-lactone; Carbonic acid esters such as dimethyl carbonate, diethyl carbonate, and ethylene carbonate. It is possible to use a mixture of more than one type of solvent.

Although the amount of the polymerization solvent used as described above cannot be determined unconditionally,
The amount is generally 10 to 2000 parts by weight per part by g.

That is, if the amount of the solvent used is less than the above 10 parts by weight, the polymerization rate of the prepolymer increases and the viscosity increases significantly, making it difficult to put it into practical use and in some cases causing gelation. Prepolymer production becomes impossible. Also.

If the solvent is more than 2000 parts by weight, seven months
In order to sufficiently increase the polymerization rate, a large amount of radical initiator is required, making it unsuitable for industrially producing prepolymers.

The polymerization reaction of the present invention is generally carried out in the presence of a radical polymerization initiator. The polymerization reaction proceeds only by heating, but it can also be carried out by irradiation with actinic rays such as ultraviolet rays and radiation. The above-mentioned radical/l' polymerization initiator is not particularly limited, and known ones can be used. Examples of typical radical polymerization initiators include benzoyl peroxide, P-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, and decanoyl peroxide.

Diacyl peroxides such as lau≠yl peroxide and acetyl peroxide, diisopropyl peroxydicarbonate, and dibutyl peroxide dicarbonate.

These include bar carbonates such as di-2-ethylhexyl peroxydicarbonate, alkyl peresters such as t-butylperoxy 2-ethylhexanate and t-butylperoxypivalate, and azo compounds such as azobisisobutyronitrile. The amount of the radical polymerization initiator to be used varies depending on the type of polymerization solvent, ii, etc., and cannot be determined unconditionally, but in general, it is possible to use 0.05 to 10 parts by weight per 100 parts by weight of unsaturated monomers containing AGAC. preferable.

In the polymerization method of the present invention, 50 to 15
A liquid prepolymer can be produced by heating at a temperature of 0° C. until a substantially saturated polymerization rate is reached, and then removing the solvent by retaining or washing with water. In addition, depending on the type of solvent used during the polymerization, it is also possible to carry out the polymerization in a pressurized case or under reduced pressure. Polymerization temperature has a large impact on the storage stability of the produced prepolymer. Although it depends on the type of radical initiator used, in general, at temperatures below 50°C, the decomposition rate of the radical initiator is slow, and it takes a very long time to complete polymerization, and the heating time is insufficient. Radical species may remain in the prepolymer produced, and viscosity may increase and gelation may occur during storage. Also, 15
A temperature of 0° C. or higher is not preferable because the produced prepolymer may be colored or thermal polymerization may proceed.

Furthermore, in carrying out the method of the present invention, the monomers containing the radical initiator of the desired device are heated in the solvent, and after reaching a saturated polymerization rate, the monomers are heated at that temperature for at least 1 hour. It is preferable to further heat the above to decompose traces of the radical initiator. Furthermore, since the polymerization reaction does not proceed with this heating treatment, the quality of the obtained polymer is almost always determined. Never.

Generally, in order to obtain a suitable liquid Brevo UV-, it is necessary to quench the polymerization before the blue-polymer obtained by low polymerization of monomers gels. Furthermore, when a liquid prepolymer is subjected to cast polymerization, it is preferable to increase the polymerization rate of the liquid prepolymer in order to prevent leakage from the mold, to prevent swelling of the gasket, to prevent shrinkage due to one-piece assembly, and the like. On the other hand, in order to facilitate degassing after cast polymerization of the liquid prepolymer, it is preferable that the viscosity of the liquid prepolymer be low. Therefore, the desired liquid bleed poly v G
In general, it is desirable to adjust the viscosity to 15 to 250 centipoise.

〔effect〕

According to the present invention, there is no fear of coloring or gelation even if the polymerization rate is increased, and a desired colorless and transparent liquid prepolymer can be easily obtained. Further, the liquid prepolymer obtained by the present invention does not gel even if left at room temperature for several months, is stable with almost no increase in viscosity, and can be stored extremely well for a long period of time. Furthermore, by subjecting the liquid prepolymer obtained by the present invention to cast polymerization, swelling from the mold,
Polymerization shrinkage.

Polymerization distortion is solved, and a good colorless and transparent AGAC polymer molded product can be obtained.

〔Example〕

EXAMPLES In order to explain the present invention more specifically, Examples will be given below, but the present invention is not limited to these Examples. The immobility of the prepolymers obtained in the examples was measured by the following test method.

(1) Viscosity (abbreviated as η) The viscosity at 25°C was measured using a Cannon-Fenske viscosity analyzer.

(2) Specific gravity (dA omitted) The specific gravity at 20°C was measured using a standard ratiometer.

Further, the obtained prepolymer containing AGAC as a main component was molded into a plate having a fin thickness of 78 fins by cast polymerization. The physical properties of the obtained molded product were measured by the following test method.

(3) Hardness (abbreviated as H2) The value on the L scale was measured using a Rockwell hardness meter.

(4) Yellowness (abbreviated as YI) Measurement was performed on a molded product with a thickness of 78 m using an SM color computer model 5M-4 manufactured by Suga Test Instruments.

Examples 1-4 Diethylene glycol bis(allyl carbonate) 24
0g was dissolved in Solvent 3001 shown in Table 1, 12g of diisoprobyl peroxycarpocarbonate was added, and after polymerization for 3 hours at the polymerization temperature shown in Table 1, the solvent was distilled off under reduced pressure. A prepolymer was obtained. The properties of the obtained prepolymer are shown in Table 1 along with the viscosity after standing at 30° C. for one month. 'Furthermore, 24% by weight of diisopropyl peroxycarbonate as a radical polymerization initiator was added to the above prepolymer and thoroughly mixed. This mixed solution was poured into a mold consisting of a glass plate with a diameter of 73 mm and a gasket made of ethylene-vinyl acetate copolymer, and cast polymerization was performed. Polymerization was carried out at 30°C using an air oven.
The temperature was gradually raised from then until it reached 80°C in 20 hours. Polymerization was further carried out at 80°C for 2 hours.

After the polymerization was completed, the mold was taken out of the air furnace, the gasket was removed, and after cooling, the polymer was peeled off from the glass mold to obtain a colorless and transparent resin having a thickness of 7.8 m. Table 1 shows the yellowness of the molded product obtained.

Comparative Example 1 The same procedure as in Examples 1 to 5 was carried out except that toluene was used as the solvent. Table 1 shows the physical properties of the obtained prepolymer and molded product.

Examples 5-7 Diethylene glycol bis(allyl carbonate) 24
09 was dissolved in 150 g of ethyl acetate, the radical initiator shown in Table 2 was added in the amount shown in Table 2, and the mixture was polymerized at 77° C. for 3 hours. The solvent was distilled off under reduced pressure to obtain a prepolymer.

The obtained prepolymer was molded into a molded product having a thickness of 7.8 mm in the same manner as in Example 1. The properties of the obtained prepolymer and molded product are shown in Table 2.17) Example 8 Propylene glycol bis(allyl carbonate))24
Dissolve 0.9 in acid ethyl 150 resistant and add diisobrobil baroxydicarbonate 1.2.9 121.7
After polymerizing at 7°C for 3 hours, the solvent was distilled off under reduced FL to obtain a prepolymer.

The obtained prepolymer was colorless and transparent, and had a specific gravity (also a2) of 1.175. The viscosity (η25) was 8 (lOI 18).

Claims (2)

[Claims] (1) A method for producing a liquid prepolymer, which comprises polymerizing an unsaturated monomer mainly composed of alkylene glycol bis(allyl carbonate) in an ester solvent, and then removing the solvent. (2) The manufacturing method according to claim 1, in which diethylene glycol bis(allyl carbonate) is used as the alkylene glycol bis(allyl carbonate).