JPH036246A - Crosslinking agent for polymer - Google Patents

Abstract

PURPOSE:To prepare a crosslinking agent which realizes a high crosslinking efficiency, yields no low-boiling compd., and prevents foaming of a molded item and worsening of a working environment by compounding a specific org. peroxide as the effective component into the crosslinking agent. CONSTITUTION:A crosslinking agent is prepd. by compounding a compd. of formula I (wherein R is pinanyl or 1-methylcyclohexyl) [e.g. 3-pinanylperoxy-3- phenylphthalid of formula II or 3-(1-methylcyclohexylperoxy)-3-phenylphthalid of formula III] as the effective component into the agent. When used to crosslink a polymer, the agent realizes a high crosslinking efficiency, yields no low- boiling compd., and prevents foaming of a molded item and worsening of a working environment.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides high crosslinking efficiency by using a specific organic peroxide when crosslinking a crosslinkable polymer using an organic peroxide. The present invention also relates to a crosslinking agent for polymers that suppresses the generation of low-boiling gases, thereby improving the mechanical strength of crosslinked products and suppressing foaming.

(Prior Art) Methods of using various organic peroxides when crosslinking polymers have been known.

Organic peroxides used for these purposes are generally dialkyl peroxides, bisalkyl peroxykecures,
Monoperoxy carbonates or alkyl peroxy esters, specifically dicumyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl 2,5-diL-butylperoxyhexane, 1.1-bisbutyl Peroxy 3,3.5-)limethylcyclohexane, isopropyl, monobutyl peroxy carbonate, and L-butyl peroxybenzoate are known.

(For example, Japanese Patent Publication No. 47-38057, Japanese Patent Publication No. 52
-31255 publication, JP-A-49-10947 publication,
(Japanese Patent Publication No. 63765703, etc.) (Problems to be Solved by the Invention) By the way, when crosslinking a polymer using the above-mentioned organic peroxide, the desired characteristics of the organic peroxide depend on the amount of the organic peroxide added. The crosslinking ratio (crosslinking efficiency) is high. In addition, various low-boiling compounds are produced as thermal decomposition products of organic peroxides. This low boiling point compound causes the polymer to foam, deforming the molded product and reducing mechanical strength. For example, JP-A-49
No. 10947 discloses a method in which an oligomer having an unsaturated bond in the main chain is used in rotation molding of polyethylene so that the molded product does not foam.

Furthermore, decomposition products often emit unpleasant odors and cause deterioration of the working environment.

There has been a demand for organic peroxides that do not have such adverse effects.

(Means for Solving the Problems) As a result of researching the problems of the above-mentioned conventional methods, the present inventors found that by using a specific organic peroxide, a compound with a higher crosslinking efficiency and a lower boiling point than before can be produced. The present invention has been completed by discovering a crosslinking agent for polymers that has significantly less oxidation.

That is, the method of the present invention is a crosslinking agent for a polymer containing a compound represented by the formula - (in the formula, R represents a vinyl group or a l-methylcyclohexyl group) as an active ingredient.

The organic peroxides used in the present invention include 3-vinanylperoxy-3-phenyl phthalide shown in 2 and 3-(1-methylcyclohexylperoxy)-3 shown in formula 3.
- phenyl phthalide.

Formula 2 Formula 3 The compounds shown in Formulas 2 and 2 can be obtained by synthesizing the corresponding hydroperoxides and 3-chloro-3-phenylphthalide in the presence of an alkali.

Examples of the crosslinked polymer used in the present invention include polyethylene, ethylene propylene copolymer (E
PM), ethylene brobylene chloride IJ 7-
(EPDM), ethylene vinyl acetate copolymer (
EVA), tetrafluoroethylene vinylidene fluoride hexafluoropropylene ternary copolymer, chlorosulfonated polyethylene, chlorinated polyethylene, polybutene-1, polyisobutyne, ethylene vinyl acetate copolymer, polybutadiene, polyisoprene, polychloroprene, butadiene styrene copolymer, natural rubber,
Examples include polyacrylate rubber, butadiene acrylonitrile copolymer, acrylonitrile butadiene styrene terpolymer, silicone rubber, polyurethane, and polysulfide.

Based on the polymer to be crosslinked, the peroxide is generally added in a range from 0.1 to 10% by weight, preferably from 1 to 3% by weight.

Also, various additives commonly used in crosslinking processes can be added to the polymer to be crosslinked, such as crosslinking coagents, antioxidants, pigments, UV stabilizers, fillers, plasticizers, etc.

In the present invention, the temperature at which the polymer and organic peroxide are mixed is generally 25 to 130°C.

The temperature for the subsequent crosslinking is generally 110 to 220°C, preferably 150 to 190°C.

(Effects of the Invention) The present invention, which uses a specific crosslinking agent, has the following characteristics.

That is, according to the present invention, when crosslinking a polymer, the crosslinking efficiency is high and low boiling point compounds are not generated, so that foaming of the molded product or deterioration of the working environment can be prevented.

(Example) Hereinafter, the present invention will be specifically explained with reference to Examples.

In addition, the abbreviations of organic peroxides used in the examples mean the following compounds.

BBPPOi 3-vinanylperoxy-3-phenylphthalide BBCPO; 3-(1-methylcyclohexylperoxy)-3-phenylphthalide DCP; dicumyl peroxide BCPO; t-butylcumyl peroxide HA25B
, 2,5-dimethyl-2,5-di-butylperoxyhexane HY25B; 2,5-dimethyl-2,5-di-butylperoxyhexane-3 BBPPO and BBCPO are produced as follows. did.

(Production of BBPPO) 12.5 g of 40% aqueous sodium hydroxide solution (0.0
, 125 mol), 25 g of benzene, and 75 g of dioxane were stirred, and while cooling with ice and keeping at 3 to 6°C, 22.6 g (0,125 mol) of pinane hydroperoxide and 3-chloro-3-phenyl were added. Phthalide 24.5
g (0.100 mol) was added. Then, at 5℃
The reaction was continued for 5 hours. The organic layer was taken out from the reaction mixture, washed twice with 10% sodium hydroxide, then two to three times with saturated brine, and then dried over anhydrous magnesium sulfate. Thereafter, the solvent was distilled off. 310 g of viscous liquid was obtained. This viscous liquid was recrystallized from methanol. 16.2 g of white crystals with a melting point of 120°C were obtained.

The active oxygen content of this crystal was determined by the iodine method and was 4.21%, with a purity of 99.3%. The obtained crystals were confirmed to be 3-vinanylperoxy-3-phenylphthalide by nmr.

(Production of BBCPO) In the production of BBPPO described above, the same operation was performed except that 16.3 g (0,125 mol) of 1-methylcyclohexyl hydroperoxide was used instead of vinylane hydroperoxide. 25.0 g of viscous liquid was obtained. The amount of active oxygen was 4.41% and the purity was 93.2%. It was confirmed by nmr to be 3-(1-methylcyclohexylperoxy)-3-phenylphthalide.

Parts 1-2 and... 1 Capacity 75! Henschel mixer (stirring blade: standard type) with an apparent specific gravity of 0.45 and a particle size of ASTM 30 mesh 9
20 kg of powdered polyethylene of 9.5% bath, Ml 30.5, density 0.956 and 0.2 g of organic peroxide shown in Table 1 were simultaneously charged and heated at about 75 Orpm for 2 minutes, 1
Mixed for 8 minutes at 500 rpm.

Using the obtained mixture, a product was obtained by a two-axis rotational molding method using a casting mold. The appearance and mechanical properties of the obtained product were as shown in Table 1.

3-4 and 2-5 0.01 equivalent of each organic peroxide and 100 g of low-density polyethylene (Sumiyokusen G401: trademark of Sumitomo Chemical Co., Ltd.) were mixed in a roll mill at 120-130''C for 3 minutes. The obtained polyethylene sheet was cut into pieces of about 1 mm square, 5 g was placed in an ampoule with an internal capacity of 15 mA, and the tube was sealed in vacuum.The ampoule was heated in an oil bath at 180°C for 30 minutes.The ampoule was cooled and placed in an ampoule. The gas components generated were analyzed using gas chromatography.Also, in order to measure the degree of crosslinking of the crosslinked polyethylene in the ampoule, about 0.3g of the sample was extracted in boiling xylene at 2000mj2 for 16 hours, and then It was dried in a drying bed at 170''C for 4 hours, and the gel fraction was measured. The results are shown in Table 2.

Table 2 The results are shown in Table 3.

0.01 equivalent of each organic peroxide and 100 g of EPDM (Explain 502; trademark of Sumitomo Chemical Co., Ltd.)
Mixed on a roll mill for 3 minutes at 0°C. Obtained EPD
The M sheet was cut into pieces of about 1 mm square, 5 g was put into an ampoule with an internal capacity of 15 d, and the tube was sealed in a vacuum.

The gas amount was analyzed using the same procedure as in Example 3 below. In addition, to measure the degree of crosslinking of the crosslinked EPDM in the ampoule, approximately 0.3 g of sample was extracted in boiling chloroform at 2000 d for 8 hours, then dried in a drying oven at 170'C for 4 hours, and the gel fraction was The rate was measured.

Tetrafluoroethylene/vinylidene fluoride/hexafluoropropylene (molar ratio 20150/30) copolymer 100 with a number average molecular weight of about 90,000 and having -Chl and -Cl (ZI (bonded iodine 10.18% by weight) at the molecular ends) parts by weight, 30 parts by weight of aluminum citrate,
4 parts by weight of triallylisocyanurate and BBPPO2,
0 parts by weight was roll kneaded. This kneaded material was press-crosslinked at 180°C for 10 minutes.

After cooling to room temperature, 5 g of the crosslinked material cut into pieces of approximately 1 mm square was placed in a glass ampoule and heated at 180° C. for 30 minutes. Thereafter, the ampoule was cooled to 20°C, and the gas in the ampoule was introduced into a measuring cylinder submerged in water to measure the amount of gas produced. The amount of generated gas was 0.1 m. Separately, the results of measuring the mechanical properties of the crosslinked material showed that the 100% tensile stress was 52 gf/c.
m", tensile strength of 105 Kgf/cm", and elongation at break of 580%.

In the main Example 7, the same operation as in Example 7 was carried out except that 2.0 g of BBCPO was used instead of BBPPOO as a crosslinking agent. As a result, the amount of gas produced was 0.2.

In addition, the results of measuring the mechanical properties of the crosslinked product were 100% tensile stress of 48 Kgf/cm" and tensile strength of 98 Kgf/cm".
cm”, and the elongation at break was 660%.

In place of BBPPOO as the crosslinking agent in Kitakin Chuuko Example 7,
The same operation as in Example 7 was performed except that 2.0 g of HA 25 B was used. As a result, the amount of gas produced was 4.3%. Analysis of the produced gas by gas mass spectroscopy revealed that the main components were methane and ethane. In addition, the results of measuring the mechanical properties of the crosslinked material were 100% tensile stress of 46 kg.
f/cm2, tensile strength of 95 Kgf/cvn'', and elongation at break of 690%.

Claims (1)

[Claims] 1. Polymer crosslinking agent whose active ingredient is a compound represented by the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R represents a pinanyl group or 1-methylcyclohexyl group.)