JPH0340724B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel vinyl pivalate copolymer, and more particularly to a copolymer comprising units based on vinyl pivalate and trifluorochloroethylene.

Conventionally, vinyl pivalate is a vinyl ester with a somewhat special structure having a plurality of methyl groups in its side chain, and only a few examples of its homopolymers and copolymers are known. In particular, as a copolymer with a fluorine-containing monomer, a three-component molecular copolymer with ethylene tetrafluoride, vinylidene fluoride, or vinyl fluoride by FBStilmer and HL Jackson has been slightly mentioned as a coating material. Only. (U.S.
Pat.3449305, Ger Offen.2213129) As a result of various studies on copolymers consisting of a combination of a vinyl pivalate monomer and a fluorine-containing vinyl monomer, the present inventors found that vinyl pivalate units and trifluorocarbon We have now discovered a new and useful copolymer consisting of ethylene chloride units, and have now completed the present invention. In other words, this copolymer is unparalleled in its chemical and physical properties, with particularly high oxygen selective permeability, visible light transmittance, mechanical strength, and chemical stability. This is sufficient to suggest the various usefulness of this copolymer. Specific application fields showing the usefulness of this copolymer include, for example, oxygen-enriching membranes, plastic lenses, coating materials, and weather-resistant films.

The structure of this copolymer may vary depending on the content ratio of the constituent monomers, molecular weight, etc., but it is essential that it essentially contains vinyl pivalate units and trifluorochloroethylene units. The content ratio of the constituent monomers is not particularly limited, but in order to make a sufficient contribution from each component, the units based on vinyl pivalate and ethylene trifluorochloride should be 10%
It is desirable that the molar ratio is 90-90/10, preferably 25/75-75-25. In addition, it is also possible to copolymerize a specific third or more component as necessary, which improves, for example, crosslinking properties, substrate adhesion,
Flexibility etc. can be imparted. Other comonomers introduced for this purpose include fluoroolefins such as ethylene tetrafluoride, vinyl fluoride, and vinylidene fluoride; vinyl esters such as vinyl acetate, vinyl benzoate, and vinyl butyrate; ethylene; Examples include α-olefins such as propylene and isobutylene, and vinyl ethers such as ethivinyl ether, butyl, vinyl ether, and hydroxyalkyl vinyl ether. The preferred molecular weight of the copolymer is not particularly limited as it varies depending on the application, but it is generally not desirable to have a molecular weight that is too small from the viewpoint of mechanical strength. A number average molecular weight of 3,000 or more, particularly 5,000 or more is preferably used for various purposes.

As a method for producing the present copolymer, a method known as a method for polymerizing vinyl monomers is suitably employed.
That is, it is a method of polymerizing in bulk or in water or an organic medium in the presence of a radical initiation source. As the polymerization method in the medium, emulsion polymerization, solution polymerization, suspension polymerization, etc. are preferably employed. When carrying out emulsion polymerization, various types of persulfates can be used as common water-soluble radical initiators alone or in combination with appropriate reducing components as a so-called redox system. Also, radical initiation sources other than persulfates may be employed, and it is also possible to use ionizing radiation sources. The actual base for such emulsion polymerization includes commonly used emulsion stabilizers, PH buffers,
It is also suitable to use a PH regulator, a chain transfer agent, a polymerization accelerator, and other additives. As the emulsifier, a fluorine compound can also be used in addition to the usual hydrocarbon emulsifier. The polymerization temperature may be appropriately selected depending on the initiator system used, and is not particularly limited, but is generally 0 to 150°C.
Degrees of degrees Celsius are used. Further, the pressure is not particularly limited as it can be changed appropriately depending on the amount of monomers charged and the temperature, but generally about 0 to 100 atmospheres is practical. On the other hand, in the case of solution polymerization, there are no particular limitations on the solvent, initiation source, PH buffer, etc. used. Solvents range from t-butanol, which has little chain transfer, to xylene, which has easy chain transfer.
It can be adopted for various purposes. Various radical initiation sources can be used, such as azo compounds, organic peroxides, and ionizing radiation. As with emulsion polymerization, the polymerization temperature and pressure can be appropriately selected depending on the type of initiator and the concentration of the monomer used, but generally 0-100°C, 0-100°C
A preferred example is about 100 atm. When employing these various polymerization methods, the proportion of monomers introduced into the reaction vessel is appropriately selected depending on the desired composition of the desired copolymer. Batch or continuous polymerization is also possible, and various commonly used methods such as charging monomers according to the composition of the monomers to be consumed can be employed.

The present copolymer obtained by such a method has, for example, an oxygen permeability number of 1.0×10 ^-10 cc·cm/cm ² ·sec·cmHg or more, an oxygen/nitrogen permeability ratio of 3.5 or more, and a visible light transmittance of 80% or more (400 ~700nm), tensile strength 200Kg/ ^m2
As described above, it is a stable polymer that exhibits useful properties such as an elongation of 1.0% or more and a Rockwell hardness of M or more.

The composition of the obtained copolymer was determined using conventional methods such as infrared absorption spectroscopy and NMR elemental analysis. In addition, various physical properties were measured according to JIS or conventional methods. That is, hardness was measured using a Rockwell hardness tester, tensile properties were measured using a Tensilon (manufactured by Toyo Baldwin, tensile speed 50 mm/m), and visible light transmittance was measured using a spectrophotometer (HIRAMA RIKA).
The refractive index was measured using an Atsube refractometer (manufactured by KENKYUJO), and the gas permeability was measured at room temperature using a Seikaken-type gas permeation measuring device (manufactured by Rika Seiki).

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 65.5 g of t-butanol, 22.4 g of vinyl pivalate (VPv), 60.9 g of chlorotrifluoroethylene (CTFE), and azobisisobutyronitrile were placed in a stainless steel autoclave with an internal volume of 260 c.c. equipped with a stirrer.
Prepare 0.038g and 0.39g of potassium carbonate,
Freeze solidify and degas with liquid nitrogen. The reaction vessel is placed in a constant temperature bath and heated, and the polymerization reaction is carried out while stirring while maintaining the temperature inside the vessel at 65°C. After 3 hours have elapsed, stirring is stopped, the reaction vessel is taken out and rapidly cooled.
The polymer solution in the reaction vessel is passed through a glass filter and then poured into filtered methanol with stirring to precipitate the polymer. After thoroughly washing the precipitated polymer with methanol, it was incubated under reduced pressure at room temperature for 16 hours, and then
By drying at 50° C. for 1.5 hours, 31.9 g of hard resinous polyvinyl pivalate was obtained. The intrinsic viscosity of the polymer at 30°C in tetrahydrofuran is
It was 1.56. The composition of the polymer determined by elemental analysis was VPv/CTFE=53.9/46.1 (molar ratio).

The copolymer was dissolved in ethyl acetate, cast on a glass plate using an applicator, dried, and peeled off from the glass surface to obtain a film with a thickness of 29 μm. The permeability coefficient of oxygen and nitrogen (P
[O ₂ ] and P[N ₂ ]) are each P[O ₂ ]6.4×
10 ^-10 , P [N ₂ ] 1.39×10 ^-10 cc・cm ² /cm・sec・cm
Hg (STP), and the ratio of P[O ₂ ]/P[N ₂ ] (α)
was extremely large at 4.6. This polymer was also dissolved in trifluorotrichloroethane.
When one drop of the 0.5% solution was dropped onto water, a good casting thin film was obtained. Therefore, this polymer is a new material that is extremely useful as a material for oxygen enrichment membranes.

Example 2 A VPv/CTFE copolymer was synthesized in the same manner as in Example 1. However, the amount of preparation is vinyl pivalate (VPv)
44.8g and trifluorochloroethylene 40.7g.

The obtained copolymer has a VPv/CTFE molar ratio=
58.6/41.4, and the intrinsic viscosity was 1.46. The infrared absorption spectrum of the polymer is shown in FIG.

The spectrum of the outer polymer shows a different pattern than the superposition of the homopolymer spectra of each component.

The physical properties, chemical properties, and oxygen permeability of this polymer are shown in Table 1, and the hydrolysis resistance is shown in Table 2.

Table-1 Physical properties Density (g/cm ² ) 1.249 Hardness (Rockwell) M38 Tensile strength (Kg/cm ² ) 410 Elongation at break (%) 4.0 Optical properties Visible light transmittance 372 nm 86% 460 90 (Sample 620 91 Gas permeable oxygen cc・cm/cm ²・sec・cmHg7.6×10 ^-10 Table-2 Immersion conditions Test results (IR analysis) PH=1 aqueous solution RT×12 days No change PH＞ 1 aqueous solution RT x 12 days 〃 36% HCl RT x 1 night 〃 0.5N NaOH 80℃ x 13 days 〃 20% NaOH 80℃ x 13 days 〃 Optical property measurement samples were press-molded at 120℃,
Although the thickness was 2.13 mm, a sample with an extremely transparent and smooth surface was obtained. Based on the above characteristics, the copolymer is considered suitable as a material for plastic lenses, contact lenses, and the like.

Example 3 A VPv/CTFE copolymer was synthesized in the same manner as in Example 1. However, the copolymerization reaction was carried out for 3.0 hours with the charged amounts of VPv9.0g and CTFE73.1g.

The obtained copolymers contained VPv and CTFE, respectively.
It was a copolymer containing 40.7 mol% and 59.3 mol%, and an intrinsic viscosity of 1.02.

The copolymer is dissolved in ethyl acetate to form a 15% polymer solution, which is then cast onto a bright aluminum plate using an applicator. After air drying, the gloss of the aluminum plate coated with the polymer was
When measured with a 60°-60° reflection gloss meter, it was 145. When this coating film was subjected to an accelerated weathering test using a Sunshine Weatherometer, it showed a gloss retention rate of 90% after 4000 hours, indicating good weather resistance. These results suggest the usefulness of this copolymer as a resin for weather-resistant paints.

Example 4 A stainless steel autoclave with a capacity of 2 was charged with 830 c.c. of ion-exchanged water, 83.1 g of t-butanol, 9.2 g of sec-butanol, 4.6 g of sodium lauryl sulfate, 5.5 g of potassium carbon, and 0.92 g of ammonium persulfate. After charging 345.3g of the autoclave, close the flange of the autoclave. After repeating deaeration and nitrogen gas pressurization (3 Kg/cm ² ) three times, 318.0 g of trifluorochloroethylene was charged after deaeration. The autoclave was heated with stirring and the reaction was carried out at 50°C for 3 hours. The reaction pressure decreases from 5.6Kg/cm ² to 4.3Kg/cm ² . While cooling the reaction vessel, unreacted
After purging the CTFE, open the flange and collect the latex. After the latex is coagulated using methanol, the precipitated polymer is over-recovered. The polymer yield after drying was 505 g.

The composition of this polymer is VPv/CTFE=58.2/
41.8, and the intrinsic viscosity was 1.56.

[Brief explanation of drawings]

FIG. 1 is an infrared absorption spectrum of a copolymer according to the present invention.

Claims (1)

[Claims] 1 The molar ratio of units based on vinyl pivalate and units based on trifluorochloroethylene is 10/90 to 90/
10 and a number average molecular weight of at least 3000.