CN100540575C - Modified polytetrafluoroethylene and its manufacturing method - Google Patents

Abstract

The invention provides the manufacture method that film-forming properties is superior, can form modified Teflon, its aqueous dispersion, aqueous dispersion composition and the above-mentioned modified Teflon of the superior overlay film of the transparency.Described modified Teflon is polymerizing tetrafluoroethylene and comonomer and the modified Teflon that obtains, it is characterized in that, the comonomer unit that described comonomer forms accounts for the 0.1 quality %～1.0 quality % of described modified Teflon, the average primary particle diameter of described modified Teflon is 220nm～500nm, and described comonomer is R 1216, perfluor (alkyl vinyl ether) and/or vinylidene.

Description

Modified polytetrafluoroethylene and its manufacturing method

technical field

The present invention relates to modified polytetrafluoroethylene, a method for producing the modified polytetrafluoroethylene, a modified polytetrafluoroethylene aqueous dispersion, and a modified polytetrafluoroethylene aqueous dispersion composition.

Background technique

Conventionally, an aqueous dispersion composition containing polytetrafluoroethylene (PTFE) resin particles is impregnated into glass fiber, carbon fiber, Kevilla port fiber, etc. to manufacture impregnated bodies such as roofing materials. In addition, high-frequency printed circuit boards, In applications such as conveyor belts and packaging, the composition is applied to a coating object and fired to form a film.

In the conventional aqueous dispersion composition containing PTFE resin particles, if the amount of immersion and application per one time exceeds a certain film thickness, cracks will occur in the film and there is a problem that the quality will be deteriorated. In order to solve this problem, a method of repeating dipping or coating steps has been used when thick-film processed products are required, but this method has problems of increased production cost and occurrence of cracks.

As a method for producing PTFE, a method of adding all the emulsifier in batches during emulsion polymerization (for example, refer to Patent Document 1), a method of intermittently adding an emulsifier during emulsion polymerization (for example, refer to Patent Document 2), and A method of polymerizing at a pressure of less than 4 kg/cm ² in the first stage of polymerization and at a pressure of 6 kg/cm ² to 30 kg/cm ² in the second stage (for example, refer to Patent Document 3).

As a method for producing PTFE, a method has also been proposed. Polymerize at a certain temperature. After polymerizing at least 30% by weight of the total amount of tetrafluoroethylene (TFE) to be polymerized, change the polymerization temperature. The amorphous index of the polymer obtained when the same amount of tetrafluoroethylene is polymerized at the above-mentioned certain temperature is at least 0.01 higher than the amorphous index of the polymer obtained by polymerizing tetrafluoroethylene at the above-mentioned certain temperature (for example, refer to the patent Document 4).

However, only changes from 40°C to 18°C, from 70°C to 90°C, or from 70°C to 92°C are described for temperature changes during the polymerization. In addition, Patent Document 4 does not specifically describe modified PTFE, and is a technique for obtaining fine powder for slurry extrusion molding.

As a method of changing the temperature during the polymerization of PTFE, the following method has also been proposed. The polymerization start temperature is 60°C or less, preferably 55°C or less, more preferably 50°C, and the polymerization is completed at a temperature higher than 55°C. The end temperature is at least 5°C higher than the above start temperature, preferably at least 10°C higher (for example, refer to Patent Document 2).

Patent Document 2 describes only an example in which polymerization starts at 40°C and terminates at 80°C for modified PTFE. In addition, Patent Document 2 describes that there is a temperature rise caused by heat of reaction and that the temperature is raised linearly, intermittently or continuously from the start to the end of the polymerization. This method requires the presence of a liquid stabilizer such as paraffin wax when the polymerization is terminated, and it is preferable that the liquid stabilizer cannot exist at a low polymerization initiation temperature.

As an aqueous dispersion composition containing PTFE resin particles, it is known that when an aqueous dispersion composition containing modified PTFE resin particles is processed into a coating such as a paint, a transparent coating can be obtained.

As modified PTFE, for example, the following modified PTFE is disclosed: modified PTFE containing 0.001 mol% to 2 mol% of chlorotrifluoroethylene as a comonomer and having an average particle diameter of about 0.2 μm to 0.5 μm (for example, refer to Patent Document 5), containing 0.04% by weight to 0.25% by weight of chlorotrifluoroethylene in the outer shell and 0.01% to 0.15% by weight in the core as comonomers, has an average particle diameter of about Modified PTFE of 0.1 μm to 0.6 μm (for example, refer to Patent Document 6).

However, these modified PTFEs use chlorotrifluoroethylene as an essential monomer, and have a disadvantage of insufficient heat resistance for some applications.

As a modified PTFE fine powder using perfluoro(alkyl vinyl ether) [PAVE] as a comonomer of modified PTFE, an average particle diameter of about 0.05 μm to 0.02% by weight and 0.3% by weight of PAVE has been proposed. 0.6 μm (for example, refer to Patent Document 7), PAVE is 0.02% to 0.3% by weight and the average particle size is about 0.05 μm to 0.5 μm (for example, refer to Patent Document 8).

However, these modified PTFEs actually have very few comonomer units or have a small average particle size, resulting in insufficient crack limit film thickness and poor transparency of the resulting film.

[Patent Document 1] Japanese Patent Publication No. 46-14466

[Patent Document 2] JP-A-2000-143707

[Patent Document 3] JP-A-60-76516

[Patent Document 4] JP-A-52-112686

[Patent Document 5] JP-A-51-36291

[Patent Document 6] JP-A-63-56532

[Patent Document 7] JP-A-64-1711

[Patent Document 8] JP-A-10-53624

Contents of the invention

In view of the above-mentioned present situation, the object of the present invention is to provide a modified polytetrafluoroethylene that is excellent in film-forming properties and capable of forming a film with excellent transparency, an aqueous dispersion thereof, an aqueous dispersion composition, and a composition of the above-mentioned modified polytetrafluoroethylene. Manufacturing method.

The modified polytetrafluoroethylene of the present invention is a modified polytetrafluoroethylene obtained by polymerizing tetrafluoroethylene and comonomers, and is characterized in that the comonomer units formed by the above-mentioned comonomers account for the proportion of the above-mentioned modified polytetrafluoroethylene 0.1% to 1.0% by mass of vinyl fluoride, the average primary particle diameter of the modified polytetrafluoroethylene is 220 to 500 nm, and the comonomer is hexafluoropropylene, perfluoro(alkyl vinyl ether) and/or Vinylidene fluoride.

The method for producing modified polytetrafluoroethylene of the present invention is a method for producing modified polytetrafluoroethylene by polymerizing tetrafluoroethylene and a comonomer in an aqueous polymerization medium (hereinafter sometimes It is called modified PTFE manufacturing method (P)), and it is characterized in that, above-mentioned polymerization comprises step (1) and step (2), and in step (1), after above-mentioned polymerization begins until relative to every liter of above-mentioned aqueous polymerization During the period when the above-mentioned tetrafluoroethylene of 1 g or more is consumed in the medium, the polymerization reaction is carried out at a polymerization pressure of 0.3 MPa or less; Polymerization was carried out under pressure.

The method for producing modified polytetrafluoroethylene of the present invention is a method for producing modified polytetrafluoroethylene by polymerizing tetrafluoroethylene and a comonomer in an aqueous polymerization medium (hereinafter sometimes It is called modified PTFE production method (Q)), it is characterized in that, above-mentioned polymerization comprises step (i) and step (ii), and in step (i), after above-mentioned polymerization starts up to every liter of above-mentioned aqueous polymerization During the period when the above-mentioned tetrafluoroethylene of 1 g or more is consumed in the medium, the polymerization reaction is carried out at the polymerization temperature X°C (55<X<70); in step (ii), after the above step (i), the polymerization temperature is Polymerization is carried out at Y°C (Y≥X+3, X is the same as above).

The modified polytetrafluoroethylene of the present invention is characterized in that it is produced by the above-mentioned modified PTFE production method (P) and modified PTFE production method (Q). The modified polytetrafluoroethylene aqueous dispersion of the present invention is characterized in that particles formed of the above-mentioned modified polytetrafluoroethylene are dispersed in an aqueous medium. The modified polytetrafluoroethylene aqueous dispersion composition of the present invention is a modified polytetrafluoroethylene aqueous dispersion composition containing a modified polytetrafluoroethylene aqueous dispersion and a surfactant added after polymerization, and its characteristics In that, the modified polytetrafluoroethylene aqueous dispersion is the above-mentioned modified polytetrafluoroethylene aqueous dispersion.

The present invention will be described in detail below.

The modified PTFE of the present invention is not particularly limited, and can be used as a powder for molding materials, but is suitable for coating compositions as resin particles constituting an aqueous dispersion composition. When used as a coating composition, by coating the coating composition on the object to be coated or immersing it in the object to be impregnated, it is possible to form on the object to be coated or on the surface of the object to be impregnated. PTFE coating.

In this specification, the concept that may include both the above-mentioned object to be coated and the object to be impregnated may be referred to as a "base material". Coating and impregnation generally refer to an operation including the steps of applying the above-mentioned coating composition on the object to be painted or immersing it in the object to be impregnated (in this specification, as a concept that may include coating and impregnation, it is sometimes referred to as "Application"), if necessary, drying by heating or the like, and then firing at a temperature equal to or higher than the melting point of the modified PTFE.

The modified polytetrafluoroethylene (modified PTFE) of the present invention is obtained by polymerizing tetrafluoroethylene (TFE) and comonomers.

The aforementioned comonomers are hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE) and/or vinylidene fluoride (VdF).

In this specification, the above "HFP, PAVE and/or VdF" may be any of the following cases: the case of using HFP without PAVE and VdF, the case of using PAVE without HFP and VdF, the case of using VdF But not using HFP and PAVE, Using HFP and PAVE but not VdF, Using VdF and PAVE but not HFP, Using VdF and HFP but not using PAVE, Using VdF, HFP and PAVE In any of these cases, when PAVE is used, one, two, or more than two types of PAVE can be used.

As the above-mentioned comonomer, PAVE and/or HFP are preferred, and PAVE is more preferred in view of the excellent transparency of the obtained film.

Examples of the above-mentioned PAVE include perfluoro(methyl vinyl ether) (PMVE), perfluoro(ethyl vinyl ether) (PEVE), perfluoro(propyl vinyl ether) (PPVE), etc., and particularly preferred PMVE and/or PPVE.

In the modified PTFE of the present invention, the comonomer unit formed from the above-mentioned comonomer is 0.1% by mass to 1.0% by mass of the modified PTFE.

For the modified PTFE of the present invention, when the comonomer unit is less than 0.1% by mass of the modified PTFE, a molded body and a film with excellent transparency cannot be formed; when it exceeds 1.0% by mass, the properties of polytetrafluoroethylene will be damaged. traits.

In the present specification, the above-mentioned "comonomer unit" is a part of the molecular structure of modified PTFE, and refers to a part formed of a comonomer. For example, when the comonomer is PPVE, the comonomer unit is a moiety represented by -[CF ₂ -CF(-OC ₃ F ₇ )]- formed from PPVE in the molecular structure of the modified PTFE.

The preferred upper limit of the comonomer unit contained in the above-mentioned modified PTFE is 0.7% by mass. In order to make the coating film obtain transparency compatible with the amount of comonomer used, the more preferred upper limit is 0.5% by mass, and more preferably The upper limit of is 0.35% by mass, and a particularly preferable upper limit is 0.3% by mass.

For the modified PTFE of the present invention, the average primary particle size is 220 nm to 500 nm.

A preferable lower limit of the average primary particle diameter is 230 nm, a more preferable lower limit is 280 nm, a preferable upper limit is 400 nm, and a more preferable upper limit is 350 nm. In this specification, the term "average primary particle diameter" refers to the average particle diameter of primary particles in the aqueous dispersion after the completion of polymerization described later.

For the modified PTFE of the present invention, since the average primary particle size is within the above-mentioned large range, especially when used in a coating composition, it can simultaneously reduce mud cracks and Reduces shrinkage cracks caused by shrinkage of the resin as it cools after firing, and greatly increases the crack limit film thickness of one coating or dipping, enabling thicker films even with one coating or dipping (thick coating sex).

In this specification, the above-mentioned property of reducing the occurrence of cracks and forming a film is sometimes referred to as "film-forming property".

For the modified PTFE of the present invention, if the average primary particle size is less than 220 nm, the above-mentioned film-forming property is poor when it is prepared and used as a coating composition; if the average primary particle size exceeds 500 nm, it is prepared as an aqueous dispersion composition When , the sedimentation of the particles formed by the modified PTFE is obvious, and the stability of the composition is poor.

Although the modified PTFE of the present invention is a modified PTFE as described above, its average primary particle size is large, and the average primary particle size can be maintained even if the ratio of comonomer units is as large as the above-mentioned range. Therefore, although the modified PTFE of the present invention has a certain thickness, it is possible to form a molded article and a film that are excellent in crack resistance and excellent in transparency.

The modified PTFE of the present invention (hereinafter sometimes referred to as "the modified PTFE (a) of the present invention") can be suitably produced by the production method of the modified PTFE of the present invention described later. In this specification, when only "modified PTFE production method" is mentioned without adding (P) or (Q), it does not distinguish from the above-mentioned modified PTFE production method (P) or modified PTFE production method (Q). , which is used as a term to summarize the two production methods.

The modified PTFE (a) of the present invention can also be produced by the following method: when carrying out the polymerization of TFE and comonomers in the presence of an emulsifier in an aqueous polymerization medium, the emulsifier is added batchwise or continuously (in this specification Sometimes called "emulsifier continuous addition method"). The above-mentioned aqueous polymerization medium will be described later.

In the above method of continuously adding the emulsifier, the initial addition amount of the emulsifier is preferably 1.0×10 ^-4 to 5.0×10 ^-2 parts by mass relative to 100 parts by mass of the aqueous polymerization medium. When it is less than 1.0×10 ^-4 parts by mass, the emulsification of the polymerization reaction system may be insufficient; when it exceeds 5.0×10 ^-2 parts by mass, the average primary particle size of the particles formed by the obtained modified PTFE may become small . A more preferable lower limit of the initial addition amount of the emulsifier is 1.0×10 ^-3 parts by mass, and a more preferable upper limit is 3.0×10 ^-2 parts by mass relative to 100 parts by mass of the aqueous polymerization medium. The "initial addition amount of the emulsifier" mentioned above is the amount of the emulsifier present in the polymerization reaction system at the start of the polymerization reaction.

Examples of the emulsifier include fluorocarbon-based emulsifiers and hydrocarbon-based emulsifiers. Fluorocarbon-based emulsifiers are preferred, and perfluorocarbon-based emulsifiers having 8 to 12 carbon atoms are more preferred.

The added amount of the above-mentioned emulsifier is preferably 1.0×10 ⁻⁴ mass% to 1.0 mass% in total of the above-mentioned aqueous polymerization medium.

When the above-mentioned emulsifier continuous addition method is used, it is not necessary to strictly control the polymerization pressure in the modified PTFE production method (P) of the present invention described later. For example, the polymerization reaction can be carried out under a certain polymerization pressure from the start to the end of the polymerization. . In the method (P) for producing modified PTFE of the present invention, the method of continuously adding the emulsifier is preferably carried out, for example, at a polymerization temperature of 50° C. to 90° C. and a polymerization pressure of 0.5 MPa to 3 MPa.

In addition, by setting the initial addition amount of the emulsifier to a low value when performing the continuous addition method of the emulsifier, the average primary particle size of the obtained modified PTFE can be further increased.

The following describes the common matters of the modified PTFE production method (P) and the modified PTFE production method (Q) of the present invention, and describes the modified PTFE production method of the present invention.

The modified PTFE manufacturing method of the present invention is to manufacture modified PTFE by carrying out tetrafluoroethylene (TFE) and comonomers in an aqueous polymerization medium.

The above-mentioned aqueous polymerization medium refers to an aqueous reaction medium in which TFE and comonomers are polymerized.

Examples of the above-mentioned aqueous polymerization medium include water, a mixed solution of water and a known water-soluble solvent, and the like, and water is preferred. In this specification, the quality of the above-mentioned aqueous polymerization medium does not include the quality of the polymerization initiator or any other additives described later.

As said water-soluble solvent, water-soluble alcohols, such as methanol, ethanol, propanol, etc. are mentioned, for example.

The above-mentioned comonomer is not particularly limited, and examples thereof include HFP, PAVE, VdF, chlorotrifluoroethylene (CTFE), and the like, and industrially, HFP, PAVE, and/or VdF are preferable. The above-mentioned "HFP, PAVE and/or VdF" is the same concept as the above-mentioned case in the modified PTFE of the present invention.

In the method for producing modified PTFE of the present invention, known polymerization initiators, other additives, and the like can be suitably added for polymerization.

Examples of the polymerization initiator include persulfates such as ammonium persulfate (APS) and potassium persulfate, organic peroxides such as disuccinic acid peroxide (DSP), and the like.

When the above-mentioned polymerization is carried out by setting the polymerization pressure under the conditions described below, other conditions can be appropriately set according to the target modified PTFE composition, production amount, and the like.

In the above-mentioned production method of modified PTFE, it is also possible to perform polymerization by appropriately adding a known liquid stabilizer. Paraffin wax is mentioned as said liquid stabilizer. The liquid stabilizer may be present at the start of the polymerization, or may be added after the start of the polymerization.

As a polymerization method in the method for producing modified PTFE of the present invention, for example, emulsion polymerization is preferable.

In the modified PTFE manufacturing method (P) of the present invention, the polymerization includes step (1) and step (2). In step (1), after the polymerization starts, there is more than 1 liter of the above-mentioned aqueous polymerization medium. During the period when 1g of tetrafluoroethylene is consumed, the polymerization reaction is carried out at a polymerization pressure less than or equal to 0.3MPa; in step (2), after the above step (1), polymerization is carried out at a polymerization pressure of 1MPa to 3Mpa reaction.

In the above step (1), the preferred lower limit of the polymerization pressure is 0.10 MPa, the more preferred lower limit is 0.20 MPa; the preferred upper limit is 0.28 MPa, and the more preferred upper limit is 0.25 MPa.

In this specification, the polymerization pressure of "1 MPa to 3 MPa" in the above step (2) includes the concept of 1.00±0.05MPa to 3.00±0.05MPa.

In the above step (2), the preferred lower limit of the polymerization pressure is 1.3MPa, the more preferred lower limit is 1.5MPa; the preferred upper limit is 2.8MPa, and the more preferred upper limit is 2.5MPa.

In general, when the polymerization pressure is high when producing modified PTFE, the copolymerizability of the comonomer decreases, and the average primary particle diameter of the obtained resin particles tends to decrease. But, for the modified PTFE manufacturing method (P) of the present invention, owing to carry out the step (1) of carrying out polymerization reaction with above-mentioned specific low pressure before carrying out the step (1) of carrying out polymerization reaction with above-mentioned specific high pressure, thereby can be in Modified PTFE with a large average primary particle size is produced without impairing the copolymerizability of the comonomer.

The modified PTFE production method (P) of the present invention includes the above-mentioned step (2), thereby shortening the polymerization time and improving productivity.

In the modified PTFE manufacturing method (Q) of the present invention, the polymerization includes step (i) and step (ii), in step (i), after the polymerization starts until there is more than 1 liter of the above-mentioned aqueous polymerization medium During the period when TFE equal to 1g is consumed, the polymerization reaction is carried out at the polymerization temperature X°C (55<X<70); in step (ii), after the above step (i), the polymerization temperature is Y°C (Y≥X +3, X is the same as above) for polymerization.

In the above-mentioned modified PTFE production method (Q), it is not necessary to strictly control the polymerization pressure, for example, the polymerization reaction may be carried out under a constant polymerization pressure from the start to the end of the polymerization. In the above step (ii), the above polymerization pressure is preferably a relatively high pressure, more preferably greater than or equal to 1 MPa.

In the above-mentioned step (i), the above-mentioned polymerization temperature X°C is preferably higher than 60°C, more preferably 62-68°C. In step (i) above, preferably the polymerization temperature is maintained at X°C throughout step (i). In the polymerization reaction, the temperature tends to rise due to the heat of reaction, but since the polymerization is carried out in an aqueous polymerization medium, temperature management is easy.

In the above-mentioned step (ii), except that the polymerization temperature is changed to Y°C, the polymerization reaction can usually be carried out under the polymerization conditions of the above-mentioned step (i). That is, in the above-mentioned step (ii), if the polymerization temperature is changed to Y°C, the polymerization reaction in the step (i) can usually be continued as it is. Therefore, the polymerization reaction in the above step (ii) is usually carried out in an aqueous polymerization medium.

The above-mentioned polymerization temperature Y°C is a temperature at least 3°C higher than the above-mentioned polymerization temperature X°C. When the polymerization reaction in step (ii) is carried out in an aqueous polymerization medium, the upper limit of the above-mentioned polymerization temperature Y°C is preferably 100°C, more preferably 95°C, and still more preferably 90°C.

As for the temperature increase range from the polymerization temperature X°C in the above step (i) to the polymerization temperature Y°C in the above step (ii), as long as the polymerization temperature Y°C is within the above range, it is preferably less than 40°C, more preferably 30°C or less. °C, more preferably less than 20 °C, particularly preferably less than or equal to 15 °C, most preferably less than 5 °C. For the modified PTFE production method of the present invention, even if the range of temperature increase from the polymerization temperature X°C in the above step (i) to the polymerization temperature Y°C in the above step (ii) is as small as the above range, the present application can be realized. purpose of the invention.

In the above step (ii), it is preferred to maintain the polymerization temperature at Y°C throughout the whole step (ii). In the polymerization reaction, the temperature tends to rise due to the heat of reaction, but since the polymerization is carried out in an aqueous polymerization medium, temperature management is easy.

As mentioned above, the modified PTFE production method (Q) of the present invention starts polymerization with the above-mentioned specific range of polymerization temperature in step (i), and the polymerization temperature of the polymerization reaction in step (ii) is higher than that of the above-mentioned step (i) The polymerization temperature of the medium polymerization reaction is at least 3°C higher, so it is possible to produce modified PTFE with a large average primary particle size without impairing the copolymerizability of the comonomer.

For the modified PTFE production method (Q) of the present invention, even if the range of temperature increase from the polymerization temperature in the above-mentioned step (i) to the polymerization temperature in the above-mentioned step (ii) is as small as the above-mentioned range, it is also possible to realize the present application. The object of the invention, thus high energy efficiency, can also increase productivity.

In the method for producing modified PTFE of the present invention, modified PTFE is produced by polymerizing TFE and comonomers in an aqueous polymerization medium, which includes a first polymerization step and a second polymerization step, and the first polymerization step is carried out during the following period Polymerization reaction: from the start of the polymerization until 1 g or more of the above-mentioned TFE is consumed per 1 liter of the above-mentioned aqueous polymerization medium; in the second polymerization step, the polymerization reaction is carried out after the first polymerization step. If the polymerization reaction of the second polymerization step is carried out at a polymerization pressure of 1 to 3 MPa, it can also be understood as (p) carrying out the polymerization reaction of the above-mentioned first polymerization step at a polymerization pressure of 0.3 MPa or less, or (q) The polymerization reaction in the above-mentioned first polymerization step is carried out at a temperature at least 3° C. lower than the polymerization temperature at which the polymerization reaction is carried out in the second polymerization step.

Modified PTFE produced by the modified PTFE production method of the present invention (hereinafter sometimes referred to as "modified PTFE (b) of the present invention") is also one of the present invention. The modified PTFE (b) of the present invention is preferably the above-mentioned modified PTFE (a) of the present invention, but the modified PTFE produced by the production method of the modified PTFE of the present invention is not necessarily the same as the modified PTFE (a).

Hereinafter, when the modified PTFE (a) and the modified PTFE (b) of the present invention are collectively referred to, (a) or (b) are not added, and only referred to as "modified PTFE of the present invention". According to the above-mentioned modified PTFE manufacturing method of the present invention, the modified PTFE (b) of the present invention is manufactured in the form of a resin dispersed in a modified PTFE aqueous dispersion (sometimes referred to as "polymerization-terminated aqueous dispersion") , the modified PTFE aqueous dispersion is obtained by polymerizing tetrafluoroethylene and comonomers in an aqueous polymerization medium. The above-mentioned aqueous polymerization medium exists as an "aqueous medium" in the above-mentioned modified PTFE aqueous dispersion.

The aforementioned modified PTFE aqueous dispersion (polymerization-terminated aqueous dispersion) is a dispersion system in which particles (primary particles) formed of modified PTFE are dispersed in the aforementioned aqueous medium.

The above-mentioned modified PTFE aqueous dispersion can have the following purposes: (A) the modified PTFE aqueous dispersion concentrate that has improved the polymer concentration is prepared by adding a surfactant; (B) the above-mentioned modified PTFE aqueous dispersion is (C) Prepare modified PTFE powder by adding surfactant and required additives to the above-mentioned modified PTFE aqueous dispersion or the above-mentioned modified PTFE aqueous dispersion concentrate, etc. Aqueous PTFE dispersion composition.

In addition, the coagulation of the above (B) causes the primary particles dispersed in the polymerization-terminated aqueous dispersion to aggregate to form secondary particles.

In this specification, the above-mentioned "modified PTFE aqueous dispersion" does not add the surfactant described in (A) and (C) after polymerization. There is a different concept of "proper PTFE aqueous dispersion composition".

Since the modified PTFE (b) of the present invention is a modified PTFE, it can form a molded article or a film excellent in transparency.

The average primary particle size of the modified PTFE (b) of the present invention is usually in the range of 220 nm to 500 nm. Therefore, the modified PTFE (b) of the present invention is excellent in film-forming properties.

The modified PTFE aqueous dispersion of the present invention is a dispersion in which the above-mentioned modified PTFE particles of the present invention are dispersed in an aqueous medium.

In the modified PTFE aqueous dispersion of the present invention, it is preferable that the amount of the solid content of the modified PTFE resin accounts for 20% by mass to 40% by mass of the modified PTFE aqueous dispersion.

In this specification, the above-mentioned modified PTFE resin solid content is a numerical value obtained as follows: at a temperature of 380 ° C, 10 g of a modified PTFE aqueous dispersion or a modified PTFE aqueous dispersion composition is dried for 45 minutes to obtain a residue, Calculate the percentage of the mass of the obtained residue to the mass ratio of the above-mentioned modified PTFE aqueous dispersion or modified PTFE aqueous dispersion composition before drying.

The modified PTFE aqueous dispersion of the present invention is usually obtained by the above-mentioned method for producing modified PTFE of the present invention, and in this case is a polymerization-terminated aqueous dispersion.

Since the modified PTFE aqueous dispersion of the present invention contains the modified PTFE of the present invention, it has excellent film-forming properties and can form a film with excellent transparency, and thus can be suitably used as a coating material.

When the modified PTFE aqueous dispersion of the present invention is used as a coating material, it can be prepared into the above-mentioned modified PTFE aqueous dispersion concentrate, modified PTFE powder, modified PTFE aqueous dispersion composition, etc. according to the application.

Since the modified PTFE aqueous dispersion of the present invention contains the modified PTFE of the present invention, it has excellent chemical resistance, heat resistance, etc., and can be prepared as a modified PTFE powder and processed into a molded body.

The modified PTFE aqueous dispersion composition of the present invention contains a modified PTFE aqueous dispersion and a surfactant added after polymerization, and the modified PTFE aqueous dispersion is the above-mentioned modified PTFE aqueous dispersion of the present invention.

In the modified PTFE aqueous dispersion composition of the present invention, the above-mentioned surfactant added after polymerization may be the same as or different from the surfactant contained in the modified PTFE aqueous dispersion.

The above-mentioned surfactant added after polymerization is not particularly limited, but known hydrocarbon-based surfactants are preferred, and surfactants containing polyoxyalkylene alkyl ethers represented by the following general formula (I) are more preferred,

ROA ¹ -H (I)

In the formula, R is a linear or branched alkyl group having 8 to 19 carbon atoms, preferably 10 to 16 carbon atoms, and ^A1 is a polyoxyalkylene chain having 8 to 58 carbon atoms. The aforementioned ^A1 preferably has a polyoxyalkylene chain having 4 to 20 oxyethylene units and 0 to 6 oxypropylene units.

The modified PTFE aqueous dispersion composition of the present invention may contain 1 type, 2 types, or 2 or more types of the above-mentioned surfactants added after polymerization.

In the modified PTFE aqueous dispersion composition of the present invention, the total amount of the surfactant added after polymerization is preferably 3 to 20 parts by mass relative to 100 parts by mass of the solid content of the modified PTFE resin. The lower limit of the total amount of the surfactant added after polymerization is more preferably 5 parts by mass, and the upper limit is more preferably 16 parts by mass relative to 100 parts by mass of the solid content of the modified PTFE resin.

In this specification, the total amount of the above-mentioned surfactant can be obtained by the amount of the surfactant that is mixed when the above-mentioned modified PTFE resin solid component and the PTFE aqueous dispersion composition are prepared (also includes the compounding amount when the PTFE aqueous dispersion is prepared) ), obtained by the compounding amount of the surfactant in the mass % of the solid content of the modified PTFE resin; it can also be obtained by the following method: at a temperature of 100° C., 10 g of the PTFE aqueous dispersion composition was dried for 60 minutes to obtain The residue was obtained, and the residue was extracted with hexane, and then the hexane was volatilized to obtain a residue, which was obtained as a percentage of the mass ratio of the residue to the mass of the modified PTFE resin before drying.

In the modified PTFE aqueous dispersion composition of the present invention, the above-mentioned modified PTFE aqueous dispersion is the above-mentioned modified PTFE aqueous dispersion of the present invention.

In the modified PTFE aqueous dispersion composition of the present invention, the above-mentioned modified PTFE aqueous dispersion can account for the range of 30% by mass to 75% by mass of the modified PTFE aqueous dispersion composition in which the solid content of the modified PTFE resin To cooperate.

In the modified PTFE aqueous dispersion composition of the present invention, the preferred lower limit of the amount of modified PTFE resin solids is 40% by mass of the modified PTFE aqueous dispersion composition, and the preferred upper limit is the modified PTFE aqueous dispersion composition 65% by mass of the substance.

The modified PTFE aqueous dispersion composition of the present invention further preferably contains a film-forming improving agent.

In the present specification, the above-mentioned "film-forming improving agent" may be used as long as the film-forming property can be improved by compounding the improving agent, compared with the case where the improving agent is not compounded.

In the film obtained by applying the modified PTFE aqueous dispersion composition of the present invention to the base material, the surfactant of the modified PTFE aqueous dispersion composition is filled in the gaps between the modified PTFE resin particles , the film-forming improver is a substance used to supplement this filling situation to improve the film-forming property.

In the present invention, the above-mentioned film-forming modifier is not particularly limited, and is preferably an acrylic resin, a silicone-based surfactant, a nonionic surfactant with a decomposition residue of 5% or more at 380° C., and/or a dry Retardant.

In this specification, one of the above four types of "acrylic resin, silicone-based surfactant, nonionic surfactant having a decomposition residue of 5% or more at 380°C, and/or a drying retarder" can be used. species, 2 species or more than 2 species.

The above-mentioned acrylic resin is not particularly limited, but a polymer composed of a methacrylate monomer is preferable.

Examples of the methacrylate-based monomer include methyl methacrylate, ethyl methacrylate, propyl methacrylate, dimethyl propyl methacrylate, butyl methacrylate, pentyl methacrylate, and Esters etc.

The above-mentioned acrylic resin is preferably prepared and used as an aqueous dispersion.

The above-mentioned acrylic resin can be prepared into a stable aqueous dispersion even if it is a homopolymer, but from the point of view of ease of preparing a stable aqueous dispersion, copolymerization using a monomer having a carboxyl group or a hydroxyl group as a suitable comonomer is preferable. thing. When the above-mentioned acrylic resin is prepared and used as an aqueous dispersion, a nonionic surfactant may be added to the aqueous dispersion if necessary in order to further improve stability.

In terms of the film-forming properties of the obtained aqueous dispersion composition, it is preferable that about 25% by mass to 50% by mass of the acrylic resin before heating remains in the temperature range of 300°C to 320°C, About 10 mass % - 20 mass % before heating remains.

Examples of the aforementioned silicone-based surfactants include those represented by the following general formula,

R ¹ ₃ SiO-(SiR ¹ ₂ O) _n -(SiR ¹ R ² O) _m -SiR ¹ ₃

In the formula, n represents an integer of 0 to 20, m represents an integer of 0 to 20, n+m>1; R ¹ is the same or different, representing an alkyl group with 1 to 30 carbon atoms, and an alkyl group with 6 to 30 carbon atoms aryl group, alkoxy group with 1 to 30 carbon atoms, aryloxy group with 6 to 30 carbon atoms or hydrogen atom; R ² is represented by -R ³ -(C ₂ H ₄ O) _q -(C ₃ H ₆ O) a substituent represented by _r -Y, R ³ represents an alkylene group with 1 to 30 carbon atoms, Y represents an alkyl group with 1 to 30 carbon atoms, q and r are the same or different, and represent 0 An integer of ˜20, q+r>1.

Some manufacturers sell the compound having the above general formula as a modified silicone oil, but it is treated as a silicone-based surfactant in this application.

Examples of the nonionic surfactant having a decomposition residue of 5% or more at 380° C. include known polyethylene oxide derivatives and the like.

In this specification, "the decomposition residue at 380° C. is 5% or more" means that the residue after heating at 380° C. for at least 10 minutes is 5% by mass or more of that before the heating.

The above-mentioned drying retardant may be generally recognized as a "drying retardant" by those skilled in the art, and examples thereof include solvents having a boiling point of about 200°C to 300°C, and more preferably water-soluble solvents.

Such solvents are preferably glycerin, diethylene glycol monoethyl ether (ethyl carbitol), diethylene glycol monobutyl ether (butyl carbitol), triethylene glycol, ethylene glycol, and 1,3-propanediol. , 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 2-butene-1,4-diol, 2-ethyl-2-hydroxymethyl-1, 3-propanediol, etc.

It is generally believed that the modified PTFE aqueous dispersion composition of the present invention is applied to a substrate to obtain a coating, and after the obtained coating is dried or heated to reduce or remove water, surfactants, etc., the above-mentioned drying retarder remains unchanged. Existing in the above-mentioned coating plays a role of filling the gap between the particles formed by the modified PTFE, thereby improving the film-forming properties.

Among the drying retardants, diethylene glycol monoalkyl ether has the effect of dissolving the acrylic resin, so the film-forming property can be further improved by using it with the acrylic resin.

In the modified PTFE aqueous dispersion composition of the present invention, it is particularly preferable to contain an acrylic resin, a silicone-based surfactant, or a nonionic surfactant having a decomposition residue of 5% or more at 380° C. as the above-mentioned film-forming improving agent. , more preferably contains an acrylic resin.

When the acrylic resin used as a film-forming modifier in the present invention is fired after coating and drying the modified PTFE aqueous dispersion composition of the present invention, it can slowly decompose while maintaining the adhesive effect on the modified PTFE. Thus, shrinkage cracks can be prevented.

In the modified PTFE aqueous dispersion composition of the present invention, the above-mentioned film-forming improver can be suitably set according to its type compounding amount, relative to 100 parts by mass of modified PTFE resin solid components, the compounding amount of the film-forming improver Preferably it is 10 mass parts or less.

With respect to the modified PTFE resin solid component of 100 mass parts, the more preferred upper limit of the above-mentioned film-forming modifier is 5 parts by mass, and the lower limit is not particularly limited, but in terms of the effect produced by the above-mentioned film-forming modifier can be obtained, preferably The lower limit of is 0.1 parts by mass.

In the modified PTFE aqueous dispersion composition of the present invention, in addition to the above-mentioned modified PTFE aqueous dispersion, surfactant and film-forming modifier, it can also be suitably within the range of not impairing the properties of the modified PTFE of the present invention. Add known additives.

Examples of the above-mentioned additives include pigments, fillers, antifoaming agents, desiccants, thickeners, smoothing agents, buffers (Hajiki inhibitors), stabilizers, and the like.

The modified PTFE aqueous dispersion composition of the present invention is not particularly limited, for example, the modified PTFE aqueous dispersion of the present invention can be added with surfactants and required film-forming modifiers and other additives while stirring. Mix to prepare the composition.

The conditions for each operation of stirring, adding, and mixing can be appropriately set according to the type and amount of the composition used, and are preferably performed at a temperature of 5°C to 40°C.

The modified PTFE aqueous dispersion composition of the present invention has the above-mentioned constitution, so in addition to improving the crack resistance and thick coatability as mentioned above, it can also greatly increase the crack limit film thickness of one application. The crack-limited film thickness for this application has conventionally been only about 2 μm, but according to the present invention, it can reach, for example, about 10 μm or more, and further can be 15 μm or more.

In this specification, the above-mentioned crack limit film thickness is measured as follows. The modified PTFE aqueous dispersion composition (5 ml) is dropped on an aluminum plate of 20 cm × 10 cm × 1.5 mm, and the coating feeder (manufactured by Yasuda Seiki Co., Ltd.) is used. ) is coated with the film thickness continuously changing between more than 0 μm and less than or equal to 30 μm, then dried at 100°C for 10 minutes and then fired at 380°C for 15 minutes, at which time the maximum film thickness without cracks is measured.

The modified PTFE aqueous dispersion composition of the present invention can obtain a thick film coating, and surprisingly, the coating has transparency and high light transmittance. Part of the light incident on the sample is reflected, and the rest of the light is transmitted. Furthermore, part of the transmitted light is diffused, and the other light goes straight. Here, transparency refers to the ratio of straight light to total transmitted light. In addition, light transmittance refers to the ratio of total transmitted light to incident light.

Since the modified PTFE of the present invention has the above-mentioned constitution, it is suitable as a material of the modified PTFE aqueous dispersion composition of the present invention.

Since the method for producing modified PTFE of the present invention has the above-mentioned constitution, the modified PTFE of the present invention can be easily prepared.

Since the modified PTFE aqueous dispersion of the present invention and the modified PTFE aqueous dispersion composition of the present invention have the above-mentioned constitution, they can be processed into a film having excellent film-forming properties, transparency, and light transmission.

Detailed ways

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples and comparative examples.

The measurement performed in each Example was performed by the following method.

(1) Modified PTFE resin solid components

At a temperature of 380°C, dry 10 g of the modified PTFE aqueous dispersion or the modified PTFE aqueous dispersion composition for 45 minutes to obtain a residue, and calculate the mass of the obtained residue to account for the above-mentioned modified PTFE aqueous dispersion or modified The percentage of the mass ratio of the neutral PTFE aqueous dispersion liquid composition, thereby obtains the content of described solid component.

(2) Average primary particle size

The average primary particle diameter is determined from the transmittance using a calibration curve based on the transmittance and the average particle diameter. The transmittance is the transmittance of projecting the projected light of 550nm to the unit length of the polytetrafluoroethylene (PTFE) aqueous dispersion adjusted to 0.22% by mass of the solid content concentration; The average particle size determined from the orientation diameter in electron micrographs.

(3) Comonomer unit amount of perfluoro(propyl vinyl ether) (PPVE)

The unit amount was obtained by multiplying the ratio of the absorbance at 995 cm ⁻¹ to the absorbance at 2360 cm ⁻¹ in the infrared absorption spectrum band by 0.95 using the powder obtained by coagulating, washing, and drying the PTFE aqueous dispersion.

(4) Comonomer unit amount of perfluoro(methyl vinyl ether) (PMVE)

The unit amount was obtained by measuring the residual amount in the reaction system with a gas chromatograph, and calculating the consumption amount from the relationship with the charged amount.

(5) Comonomer unit amount of hexafluoropropylene (HFP)

The unit amount was obtained by multiplying the ratio of the absorbance at 983 cm ⁻¹ to the absorbance at 935 cm ⁻¹ in the infrared absorption band by 0.3 using a powder obtained by coagulating, washing, and drying the PTFE aqueous dispersion.

(6) Surfactant dosage

From the modified PTFE resin solid content obtained by the above (1) and the compounding amount of the surfactant when preparing the modified PTFE aqueous dispersion composition (also including the compounding amount when the modified PTFE aqueous dispersion is prepared), the surface The blending amount of the activator was calculated based on the mass % of the solid content of the modified PTFE resin.

(7) Crack limit film thickness

Drop 5ml of the modified PTFE aqueous dispersion composition on a 20cm×10cm×1.5mm aluminum plate, and use a coating feeder (manufactured by Yasuda Seiki Co., Ltd.) to continuously change the film thickness between more than 0 μm and less than or equal to 30 μm On the other hand, it applied once, dried at 100 degreeC for 10 minutes, and baked at 380 degreeC for 15 minutes. Cracks will occur in the part with a thicker film thickness, and the maximum film thickness without cracks is taken as the crack limit film thickness.

(8) Transparency and light transmission

The film produced when evaluating the above-mentioned crack limit film thickness was peeled off from the aluminum plate, and the total light transmittance and haze value at a film thickness of 5 μm were measured using a direct-reading haze meter (manufactured by Toyo Seiki Seisakusho Co., Ltd.).

The total light transmittance indicates the ratio of light transmission, and the larger the value, the better the light transmittance. The haze value indicates the ratio of diffused light in transmitted light, and a smaller value indicates better transparency.

Example 1

Add 3,600 g of deionized water, 180 g of paraffin wax with a melting point of 56° C., and 3.6 g of perfluorooctanoic acid ammonium into a stainless steel autoclave with a stainless steel paddle-type stirring paddle and a temperature-regulating sleeve, and an inner capacity of 6 L, and replace it with nitrogen three times , and replaced with tetrafluoroethylene (TFE) gas twice to remove the oxygen in the system, pressurized TFE gas to make the internal pressure 0.05MPa, stirred at 160rpm and kept the internal temperature at 70°C.

Then, press 2g of perfluoro(propyl vinyl alcohol) (PPVE) with TFE, and then press with TFE the aqueous solution formed by dissolving 65mg of ammonium persulfate (APS) in 10g of water, so that the internal pressure is 0.25MPa and Stop adding TFE and start step (1). Subsequently, as the reaction proceeds, the internal pressure will decrease, and TFE will be added when it is reduced to 0.20MPa, and the internal pressure will rise to 1.50MPa, and step (2) will start.

During the reaction, while maintaining the internal temperature at 70°C and the stirring rate at 160 rpm, step (2) was continued, and TFE was continuously supplied to keep the internal pressure at 1.50±0.05 MPa.

After the addition of APS, when the TFE consumed in the reaction reached 1500 g (the reaction time is 4.8 hours: the total reaction time of step (1) and step (2), the same applies hereinafter), the stirring and supply of TFE were stopped, and the gas in the autoclave was released. Up to normal pressure, thereby obtaining the modified PTFE aqueous dispersion. In the obtained modified PTFE aqueous dispersion, the solid content of the modified PTFE resin is about 30%, the average primary particle size is 329nm, and the comonomer unit of the modified PTFE is 0.11% by mass of the modified PTFE.

To 1000 g of the obtained modified PTFE aqueous dispersion, 40 g of surfactant TDS-80C (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., polyoxyethylene alkyl ether) and 160 g of pure water were added, and the modified PTFE was left to stand at 70°C to obtain modified Modified PTFE water-based dispersion concentrated product with solid content of PTFE resin greater than or equal to 65%. Surfactant TDS-120 (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., polyoxyethylene alkyl ether) and pure water were added thereto to obtain a modified PTFE resin with a solid content of 53% by mass and a surfactant dose of 13% by mass of the modified PTFE. % modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 14 μm, the total light transmittance was 94.6%, and the haze value was 11.3%.

Example 2

Except adding 4g PPVE, implement the same operation with embodiment 1, obtain modified PTFE aqueous dispersion in 5.4 hours with the reaction time. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 283 nm, and the comonomer unit of the modified PTFE was 0.25% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. The obtained modified PTFE aqueous dispersion composition had a crack limit film thickness of 11 μm, a total light transmittance of 96.3%, and a haze value of 8.4%.

Example 3

Except adding 8g PPVE, implement the same operation with embodiment 1, be 8.0 hours to obtain modified PTFE aqueous dispersion with the reaction time. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 234 nm, and the comonomer unit in the solid content of the modified PTFE resin was 0.48% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 6 μm, the total light transmittance was 98.1%, and the haze value was 6.8%.

Example 4

Except adding 2g perfluorinated (methyl vinyl ether) (PMVE) instead of 2g PPVE, implement the same operation as in Example 1, obtain the modified PTFE aqueous dispersion in 5.8 hours with the reaction time. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 305 nm, and the comonomer unit of the modified PTFE was 0.13% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. The obtained modified PTFE aqueous dispersion composition had a crack limit film thickness of 14 μm, a total light transmittance of 94.0%, and a haze value of 13.1%.

Example 5

Except adding 4g PMVE instead of 2g PPVE, implement the same operation as in Example 1, obtain the modified PTFE aqueous dispersion in 6.5 hours with the reaction time. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 258 nm, and the comonomer unit of the modified PTFE was 0.29% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 10 μm, the total light transmittance was 95.4%, and the haze value was 11.4%.

Example 6

Except adding 8g PMVE instead of 2g PPVE, implement the same operation as in Example 1, obtain the modified PTFE aqueous dispersion in 9.4 hours with the reaction time. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 221 nm, and the comonomer unit of the modified PTFE was 0.64% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 6 μm, the total light transmittance was 98.0%, and the haze value was 7.2%.

Example 7

Except adding 3g hexafluoropropylene (HFP) instead of 2g PPVE, implement the same operation as in Example 1, obtain the modified PTFE aqueous dispersion in 4.8 hours with the reaction time. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 298 nm, and the comonomer unit of the modified PTFE was 0.12% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. The obtained modified PTFE aqueous dispersion composition had a crack limit film thickness of 13 μm, a total light transmittance of 94.0%, and a haze value of 13.4%.

Example 8

Except adding 4g HFP instead of 2g PPVE, implement the same operation as in Example 1, obtain the modified PTFE aqueous dispersion in 5.2 hours with the reaction time. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 290 nm, and the comonomer unit of the modified PTFE was 0.15% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 12 μm, the total light transmittance was 94.4%, and the haze value was 12.8%.

Example 9

Except adding 8g HFP instead of 2g PPVE, implement the same operation as in Example 1, obtain the modified PTFE aqueous dispersion in 7.1 hours with the reaction time. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 228 nm, and the comonomer unit of the modified PTFE was 0.28% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 7 μm, the total light transmittance was 95.1%, and the haze value was 11.5%.

Example 10

Except that adding 4g PPVE, internal pressure is 1.00 ± 0.05MPa under continuation of step (2), implement the same operation as Example 1, obtain modified PTFE aqueous dispersion in 7.4 hours with the reaction time. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 301 nm, and the comonomer unit of the modified PTFE was 0.28% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 12 μm, the total light transmittance was 96.1%, and the haze value was 8.0%.

Example 11

Except that adding 4g PPVE, internal pressure is 2.70 ± 0.05MPa under continuation step (2), implement the same operation with embodiment 1, be 3.5 hours to obtain modified PTFE aqueous dispersion with the reaction time. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 237 nm, and the comonomer unit of the modified PTFE was 0.20% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 8 μm, the total light transmittance was 95.7%, and the haze value was 8.9%.

Example 12

Add 3,600 g of deionized water, 180 g of paraffin wax with a melting point of 56° C., and 0.1 g of perfluorooctanoic acid ammonium into a stainless steel autoclave with a stainless steel paddle-type stirring paddle and a temperature-regulating sleeve, and an inner capacity of 6 L, and replace it with nitrogen three times , and replaced with TFE gas twice to remove oxygen in the system, pressurized TFE gas to make the internal pressure 0.05MPa, stirred at 160rpm and kept the internal temperature at 70°C.

Then, press 6g PPVE with TFE, then press the aqueous solution formed by dissolving 65mg of APS in 10g water with TFE, so that the internal pressure is 2.0MPa, and start step (2).

During the reaction, the internal temperature was kept at 70°C and the stirring speed was 160 rpm, and the step (2) was continued, and TFE was continuously supplied to keep the internal pressure at 2.00±0.05 MPa. In addition, ammonium perfluorooctanoate was continuously supplied at a rate of 0.1 g of ammonium perfluorooctanoate/43 g of consumption of TFE.

After adding APS, when TFE consumed during the reaction reached 1500 g (reaction time: 3.9 hours), stirring was stopped and supply of TFE was stopped. The amount of ammonium perfluorooctanoate added is 3.6 g in total including the amount added before the reaction. The gas in the autoclave was vented to normal pressure to obtain an aqueous dispersion of modified PTFE having a solid content of the modified PTFE resin of about 30% by mass. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 293 nm, and the comonomer unit of the modified PTFE was 0.26% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 10 μm, the total light transmittance was 95.8%, and the haze value was 9.1%.

Example 13

Except adding 6g PMVE instead of 6g PPVE, implement the same operation as in Example 12, obtain the modified PTFE aqueous dispersion in 4.8 hours with the reaction time. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 280 nm, and the comonomer unit of the modified PTFE was 0.32% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 10 μm, the total light transmittance was 95.7%, and the haze value was 11.0%.

Example 14

Except adding 6g HFP instead of 6g PPVE, implement the same operation as in Example 12, obtain the modified PTFE aqueous dispersion in 3.8 hours with the reaction time. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 301 nm, and the comonomer unit of the modified PTFE was 0.18% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 13 μm, the total light transmittance was 94.9%, and the haze value was 12.3%.

Example 15

Except adding 1g PPVE, implement the same operation with embodiment 1, be 4.1 hours to obtain modified PTFE aqueous dispersion with reaction times. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 350 nm, and the comonomer unit of the modified PTFE was 0.07% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 16 μm, the total light transmittance was 93.8%, and the haze value was 15.4%. The numerical value of the crack limit film thickness was good, but compared with Example 1, the light transmittance was inferior.

Example 16

Except adding 1g PMVE instead of 2g PPVE, implement the same operation as in Example 1, obtain the modified PTFE aqueous dispersion in 5.0 hours with the reaction time. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 327 nm, and the comonomer unit of the modified PTFE was 0.09% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 14 μm, the total light transmittance was 93.5%, and the haze value was 16.3%. The numerical value of the crack limit film thickness was good, but compared with Example 4, the light transmittance was inferior.

Example 17

Except adding 1g HFP instead of 2g PPVE, implement the same operation as in Example 1, obtain the modified PTFE aqueous dispersion in 3.3 hours with the reaction time. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 354 nm, and the comonomer unit of the modified PTFE was 0.03% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 18 μm, the total light transmittance was 92.8%, and the haze value was 17.9%. The numerical value of the crack limit film thickness was good, but compared with Example 7, the light transmittance was inferior.

Example 18

Except adding 5.4g ammonium perfluorooctanoate and 10g PPVE, implement the same operation as in Example 1, obtain the modified PTFE aqueous dispersion in 5.8 hours with the reaction time. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 197 nm, and the comonomer unit of the modified PTFE was 0.64% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. In the obtained modified PTFE aqueous dispersion composition, the crack-limited film thickness was less than 5 μm.

Example 19

Except adding 4g PPVE, making internal pressure constant to be the scope of 0.80 ± 0.05MPa and continue polymerization reaction, implement the same operation as Example 1, obtain the modified PTFE aqueous dispersion in 10.2 hours with the reaction time. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 308 nm, and the comonomer unit of the modified PTFE was 0.30% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 12 μm, the total light transmittance was 96.4%, and the haze value was 7.8%.

The numerical values of the crack limit film thickness and light transmittance were good, but the polymerization time was extremely long compared with Example 2.

Example 20

Add 4g PPVE, then use TFE to press into the aqueous solution formed by dissolving 65mg APS in 10g water, stop adding TFE when the internal pressure is 0.40MPa, start the first polymerization step, add TFE when the internal pressure is reduced to 0.35MPa, Except that the second polymerization step was continued at an internal pressure of 1.50±0.05 MPa, the same operation as in Example 1 was carried out, and a modified PTFE aqueous dispersion was obtained with a reaction time of 4.4 hours.

In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 204 nm, and the comonomer unit of the modified PTFE was 0.18% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. In the obtained modified PTFE aqueous dispersion composition, the crack-limited film thickness was less than 5 μm.

Example 21

Add 3,600 g of deionized water, 180 g of paraffin wax with a melting point of 56° C., and 0.1 g of perfluorooctanoic acid ammonium into a stainless steel autoclave with a stainless steel paddle-type stirring paddle and a temperature-regulating sleeve, and an inner capacity of 6 L, and replace it with nitrogen three times , and replaced with tetrafluoroethylene (TFE) gas twice to remove oxygen in the system, pressurize TFE gas to make the internal pressure 0.05MPa, stir at 160rpm and keep the internal temperature at 65°C.

Then, press 4.0g PPVE with TFE, then press the aqueous solution formed by dissolving 18mg APS in 10g water with TFE, so that the internal pressure is 2.7MPa, and start step (i). After 30 minutes the internal temperature was raised to 68°C and step (ii) was started.

During the reaction, while maintaining the internal temperature at 68°C and the stirring speed at 160 rpm, the step (ii) was continued, and TFE was continuously supplied to keep the internal pressure at 2.70±0.05 MPa. In addition, ammonium perfluorooctanoate was continuously supplied at a rate of 0.1 g of ammonium perfluorooctanoate/43 g of TFE consumption, and PPVE was continuously supplied at a rate of 0.1 g of PPVE/150 g of TFE consumption.

After adding APS, when the TFE consumed in the reaction reaches 1500g (reaction time is 4.6 hours), stop stirring and supply TFE, the addition amount of perfluorooctanoic acid ammonium includes the addition amount before reaction is 3.6g altogether, the addition amount of PPVE includes the addition amount before reaction The amount of addition is 5.0g in total. The gas in the autoclave was vented to normal pressure to obtain an aqueous dispersion of modified PTFE having a solid content of the modified PTFE resin of about 30% by mass. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 248 nm, and the comonomer unit of the modified PTFE was 0.11% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 8 μm, the total light transmittance was 94.0%, and the haze value was 11.6%.

Example 22

Add 3,600 g of deionized water, 180 g of paraffin wax with a melting point of 56° C., and 0.1 g of perfluorooctanoic acid ammonium into a stainless steel autoclave with a stainless steel paddle-type stirring paddle and a temperature-regulating sleeve, and an inner capacity of 6 L, and replace it with nitrogen three times , and replaced with tetrafluoroethylene (TFE) gas twice to remove oxygen in the system, pressurize TFE gas to make the internal pressure 0.05MPa, stir at 160rpm and keep the internal temperature at 65°C.

Next, press 5.0g PPVE with TFE, then press the aqueous solution formed by dissolving 25mg APS in 10g water with TFE, so that the internal pressure is 2.7MPa, and start step (i). After 30 minutes the internal temperature was raised to 70°C and step (ii) was started.

During the reaction, the internal temperature was kept at 70° C. and the stirring speed was 160 rpm, and the step (ii) was continued, and TFE was continuously supplied to keep the internal pressure at 2.70±0.05 MPa. In addition, ammonium perfluorooctanoate was continuously supplied at a rate of 0.1 g of ammonium perfluorooctanoate/43 g of consumption of TFE.

After adding APS, when the TFE consumed in the reaction reached 1500 g (the reaction time was 2.7 hours), the stirring and supply of TFE were stopped, and the amount of ammonium perfluorooctanoate added was 3.6 g in total including the amount before the reaction. The gas in the autoclave was vented to normal pressure to obtain an aqueous dispersion of modified PTFE having a solid content of the modified PTFE resin of about 30% by mass. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 260 nm, and the comonomer unit of the modified PTFE was 0.11% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 10 μm, the total light transmittance was 94.4%, and the haze value was 12.1%.

Example 23

Add 3,600 g of deionized water, 180 g of paraffin wax with a melting point of 56° C., and 0.1 g of perfluorooctanoic acid ammonium into a stainless steel autoclave with a stainless steel paddle-type stirring paddle and a temperature-regulating sleeve, and an inner capacity of 6 L, and replace it with nitrogen three times , and replaced with tetrafluoroethylene (TFE) gas twice to remove oxygen in the system, pressurize TFE gas to make the internal pressure 0.05MPa, stir at 160rpm and keep the internal temperature at 65°C.

Next, press 5.0g PPVE with TFE, then press the aqueous solution formed by dissolving 18mg APS in 10g water with TFE, so that the internal pressure is 2.7MPa, and start step (i). After 30 minutes the internal temperature was raised to 70°C and step (ii) was started.

During the reaction, the internal temperature was kept at 70° C. and the stirring speed was 160 rpm, and the step (ii) was continued, and TFE was continuously supplied to keep the internal pressure at 2.70±0.05 MPa. In addition, ammonium perfluorooctanoate was continuously supplied at a rate of 0.1 g of ammonium perfluorooctanoate/43 g of consumption of TFE.

After adding APS, when the TFE consumed in the reaction reached 1500 g (the reaction time was 3.9 hours), the stirring and supply of TFE were stopped, and the amount of ammonium perfluorooctanoate added was 3.6 g in total including the amount before the reaction. The gas in the autoclave was vented to normal pressure to obtain an aqueous dispersion of modified PTFE having a solid content of the modified PTFE resin of about 30% by mass. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 271 nm, and the comonomer unit of the modified PTFE was 0.11% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. For the obtained modified PTFE aqueous dispersion composition, the crack limit film thickness was 11 μm, the total light transmittance was 94.3%, and the haze value was 11.8%.

Example 24

Add 3,600 g of deionized water, 180 g of paraffin wax with a melting point of 56° C., and 0.1 g of perfluorooctanoic acid ammonium into a stainless steel autoclave with a stainless steel paddle-type stirring paddle and a temperature-regulating sleeve, and an inner capacity of 6 L, and replace it with nitrogen three times , and replaced with tetrafluoroethylene (TFE) gas twice to remove the oxygen in the system, pressurized TFE gas to make the internal pressure 0.05MPa, stirred at 160rpm and kept the internal temperature at 70°C.

Next, 5.0 g of PPVE was injected with TFE, and then an aqueous solution obtained by dissolving 18 mg of APS in 10 g of water was injected with TFE, so that the internal pressure was 2.7 MPa, and the polymerization step was started.

During the reaction, the polymerization step was continued while maintaining the internal temperature at 70°C and the stirring rate at 160 rpm, and TFE was continuously supplied so that the internal pressure was always kept at 2.70±0.05 MPa. In addition, ammonium perfluorooctanoate was continuously supplied at a rate of 0.1 g of ammonium perfluorooctanoate/43 g of consumption of TFE.

After adding APS, when the TFE consumed in the reaction reached 1500g (the reaction time was 3.4 hours), the stirring and supply of TFE were stopped, and the amount of ammonium perfluorooctanoate added was 3.6g in total including the amount before the reaction. The gas in the autoclave was vented to normal pressure to obtain an aqueous dispersion of modified PTFE having a solid content of the modified PTFE resin of about 30% by mass. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 216 nm, and the comonomer unit of the modified PTFE was 0.12% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. In the obtained modified PTFE aqueous dispersion composition, the crack-limited film thickness was less than 5 μm.

Example 25

Add 3,600 g of deionized water, 180 g of paraffin wax with a melting point of 56° C., and 0.1 g of perfluorooctanoic acid ammonium into a stainless steel autoclave with a stainless steel paddle-type stirring paddle and a temperature-regulating sleeve, and an inner capacity of 6 L, and replace it with nitrogen three times , and replaced with tetrafluoroethylene (TFE) gas twice to remove oxygen in the system, pressurize TFE gas to make the internal pressure 0.05MPa, stir at 160rpm and keep the internal temperature at 65°C.

Next, 5.0 g of PPVE was injected with TFE, and then an aqueous solution obtained by dissolving 18 mg of APS in 10 g of water was injected with TFE, so that the internal pressure was 2.7 MPa, and the polymerization step was started.

During the reaction, the polymerization step was continued while maintaining the internal temperature at 65°C and the stirring rate at 160 rpm, and TFE was continuously supplied to keep the internal pressure at 2.70±0.05 MPa from time to time. In addition, ammonium perfluorooctanoate was continuously supplied at a rate of 0.1 g of ammonium perfluorooctanoate/43 g of consumption of TFE.

After the addition of APS, it took 2.1 hours for the TFE consumed in the reaction to reach 500 g, and it took a longer time to obtain about 30% by mass of the solid content of the modified PTFE resin. There was a problem in productivity, so the stirring and supply of TFE were stopped.

Example 26

Add 3,600 g of deionized water, 180 g of paraffin wax with a melting point of 56° C., and 0.1 g of perfluorooctanoic acid ammonium into a stainless steel autoclave with a stainless steel paddle-type stirring blade and a temperature-regulating sleeve, and an inner capacity of 6 L, and replace it with nitrogen three times , and replaced with tetrafluoroethylene (TFE) gas twice to remove the oxygen in the system, pressurized TFE gas to make the internal pressure 0.05MPa, stirred at 160rpm and kept the internal temperature at 70°C.

Next, 5.0 g of PPVE was pressed in with TFE, and an aqueous solution formed by dissolving 18 mg of APS in 10 g of water was pressed in with TFE, so that the internal pressure was 2.7 MPa, and the first polymerization step was started. After 30 minutes, the internal temperature was raised to 75°C, and the second polymerization step was started.

During the reaction, the second polymerization step was continued while maintaining the internal temperature at 75°C and the stirring rate at 160 rpm, and TFE was continuously supplied to keep the internal pressure at 2.70±0.05 MPa at all times. In addition, ammonium perfluorooctanoate was continuously supplied at a rate of 0.1 g of ammonium perfluorooctanoate/43 g of consumption of TFE.

After adding APS, when the TFE consumed in the reaction reached 1500 g (the reaction time was 2.7 hours), the stirring and supply of TFE were stopped, and the amount of ammonium perfluorooctanoate added was 3.6 g in total including the amount before the reaction. The gas in the autoclave was vented to normal pressure to obtain an aqueous dispersion of modified PTFE having a solid content of the modified PTFE resin of about 30% by mass. In the obtained modified PTFE aqueous dispersion, the average primary particle diameter was 209 nm, and the comonomer unit of the modified PTFE was 0.14% by mass of the modified PTFE.

This modified PTFE aqueous dispersion was concentrated in the same manner as in Example 1 to obtain a modified PTFE aqueous dispersion composition. In the obtained modified PTFE aqueous dispersion composition, the crack-limited film thickness was less than 5 μm.

Possibility of industrial application

Since the modified PTFE of the present invention has the above-mentioned constitution, it is suitable as a material of the modified PTFE aqueous dispersion composition of the present invention.

Since the method for producing modified PTFE of the present invention has the above configuration, the modified PTFE of the present invention can be easily prepared.

Since the modified PTFE aqueous dispersion of the present invention and the modified PTFE aqueous dispersion composition of the present invention have the above-mentioned constitution, they can be processed into a film having excellent film-forming properties, glossiness, and transparency.

Claims (3)

1. A modified polytetrafluoroethylene aqueous dispersion composition, characterized in that it is a modified polytetrafluoroethylene aqueous dispersion containing a modified polytetrafluoroethylene aqueous dispersion and a surfactant added after polymerization Composition, the modified polytetrafluoroethylene aqueous dispersion is formed by dispersing particles formed by modified polytetrafluoroethylene in an aqueous medium, and the modified polytetrafluoroethylene is polymerized tetrafluoroethylene and copolymerized Modified polytetrafluoroethylene obtained from a monomer, wherein the comonomer unit formed by the comonomer accounts for 0.1% to 1.0% by mass of the modified polytetrafluoroethylene, and the modified polytetrafluoroethylene The average primary particle diameter of ethylene is 220nm-500nm, and the comonomer is hexafluoropropylene, perfluoro(alkyl vinyl ether) and/or vinylidene fluoride. 2, a kind of manufacture method of modified polytetrafluoroethylene aqueous dispersion composition, it is the manufacture method of the modified polytetrafluoroethylene aqueous dispersion composition described in claim 1, and the manufacture method is characterized in that, Said modified polytetrafluoroethylene is manufactured by carrying out the polymerization of tetrafluoroethylene and comonomer in aqueous polymerization medium, said polymerization comprises step (1) and step (2), in step (1), in Carry out the polymerization reaction at a polymerization pressure of less than or equal to 0.3Mpa after the start of the polymerization until the tetrafluoroethylene of 1 g or more is consumed relative to 1 liter of the aqueous polymerization medium; in step (2) In the method, after the step (1), the polymerization reaction is carried out at a polymerization pressure of 1Mpa to 3Mpa. 3. A manufacturing method of a modified polytetrafluoroethylene aqueous dispersion composition, which is a manufacturing method of the modified polytetrafluoroethylene aqueous dispersion composition according to claim 1, and the manufacturing method is characterized in that the Said modified polytetrafluoroethylene is produced by carrying out the polymerization of tetrafluoroethylene and comonomer in aqueous polymerization medium, said polymerization comprises step (i) and step (ii), in step (i), in During the period after the start of the polymerization until 1 g or more of the tetrafluoroethylene is consumed per 1 liter of the aqueous polymerization medium, the polymerization reaction is carried out at a polymerization temperature of X°C, wherein 55<X<70; in the step In (ii), after the step (i), the polymerization reaction is carried out at the polymerization temperature Y°C, wherein Y≧X+3, and X is the same as above.