TW202100619A - Composition comprising fluororesin and methods of producing the composition and a fluororesin dispersion - Google Patents

Abstract

A composition, a method of producing the composition and a method of producing a fluororesin dispersion from the composition are provided, wherein the composition comprises: (i) a fluororesin having an average particle diameter of 1 μm or more and 5 μm or less and a maximum particle size of 10 μm or less; (ii) a dispersant; and (iii) an organic solvent, wherein percentage by mass of the organic solvent in the composition is 0.2% or less.

Description

Composition containing fluororesin and method for producing the composition and fluororesin dispersion

The present invention relates to a composition containing a fluororesin, and a method for producing the composition and a fluororesin dispersion.

Fluorine resins are used as coatings because they have the characteristics of chemical resistance, heat resistance, low coefficient of friction and electrical insulation. Specifically, fluororesin is used as a coating in high-frequency circuit boards due to its excellent dielectric properties. In a typical process for manufacturing high-frequency circuit boards, fluororesin is processed into fine particles, which are dispersed in a dispersion medium containing a matrix resin, and then laminated with conductors such as copper foil and the like. Then, the resulting panel is further processed by etching and similar processes to form a high-frequency circuit board.

Since the matrix resin commonly used in the above manufacturing process is soluble in a hydrocarbon solvent, the fluororesin must be dispersed in the hydrocarbon solvent first. However, due to its low interfacial tension, the fluororesin has poor wettability to hydrocarbon media and is difficult to disperse in the media.

Moreover, considering the relatively high specific gravity of the fluororesin, it is actually difficult to avoid separation in the fluororesin dispersion. Conventionally, industrial response must be performed, for example, continuous stirring is used to maintain the dispersed state, and the pot life after the dispersion is set.

This separation problem is particularly noticeable during transportation. Another problem that may arise during the transportation of the fluororesin dispersion is that the handling of organic solvents is usually dangerous, which not only increases transportation costs, but also increases transportation time.

Various methods for the dispersion technology of fluororesin have been proposed.

JP-A-2017-193655 discloses a fluororesin dispersion liquid, which contains a dispersant having a thermally decomposable group of a specific oxyalkylene chain, fluororesin particles, and water or organic solvent .

JP-A-1987-121700 discloses a fluororesin dispersion liquid characterized by dispersing fluororesin powder having a particle size of 2 μm or less in an organic solvent.

Japanese Patent No. 2516241 discloses a technique of dispersing fluorine-containing resin powder having a particle diameter of 2 μm or less in an aqueous medium in the presence of a nonionic surfactant and a thickening agent.

Japanese Patent No. 4255169 discloses a dispersant with an organosiloxane structure that uniformly disperses fibrillated PTFE.

Japanese Patent No. 5195425 discloses a technique of bringing a solution in which a fluororesin is substantially dispersed in an aqueous medium to an ion exchange resin, adding an electrolyte and an anionic emulsifier, and then performing phase separation and concentration to obtain an aqueous fluororesin solution .

JP-A-1998-176002 discloses a technique in which polymer particles insoluble in organic solvents are dispersed by a polymer having an acrylic skeleton and a fluoroalkyl group in the side chain.

US 2013/0149540 discloses a charging roll composition (charging roll composition) for improving the copy quality of a dry copier, and in an example discloses a polymerization roll composition having an acrylic skeleton and a fluoroalkyl group in the side chain The technology to disperse polytetrafluoroethylene resin particles.

WO 2018070420 discloses a composition by mixing a water-containing fluoropolymer having specific sulfonic acid groups and carboxyl groups in its structure with water, and performing mesh filtration with a mesh size of 20 μm to obtain dispersion 50% of the composition. It is disclosed that the powder is dried with a work amount of 200 W or less.

As mentioned above, Japanese Patent No. 2516241 and Japanese Patent No. 5195425 disclose the use of water as a dispersion medium. However, since the latent heat of water evaporation is great, using water as a dispersion medium increases the time it takes to apply the fluororesin coating to the substrate. Furthermore, the presence of dispersing agents and thickeners for stabilizing the aqueous dispersion can cause the fluororesin to lose its dielectric properties.

JP-A-1998-176002 and US 2013/0149540 disclose a technique for manufacturing a non-aqueous dispersion by using a polymer having an acrylic skeleton and a fluoroalkyl group in the side chain. However, in the presence of non-fluorine parts in the polymer, in the application of high-frequency integrated circuits, it is possible that the properties of the fluororesin may be disturbed.

WO 2018070420 discloses an ion exchange resin having a sulfonic acid group or a carboxyl group, which has a high affinity for water as the dispersion solvent itself, but cannot be used in high-frequency circuit boards that require electrical insulation. The possibility of dispersing the ion exchange resin in an organic solvent other than water is also suggested, but an example is not shown.

According to an example of the present disclosure, a fluororesin-containing composition, a method for producing the composition, and a method for producing a fluororesin dispersion are provided as claimed in the independent claim. Some optional features are defined in the subsidiary request item.

Examples of the composition and the method of producing the composition and the method of producing the fluororesin dispersion from the composition are as follows.

Figure 1A illustrates the steps of forming an example of the composition 104 of the present disclosure. The composition 104 in this case is a fluororesin composition. In this example, the fluororesin composition 104 is a dry solid. First, in step 1, the following ingredients are mixed together: (a) fluororesin powder, (b) dispersant, (c) solvent, and (d) dispersed beads to form a mixture 101. In addition to dispersing beads, other suitable dispersing aids can also be used. In step 2, regarded as the dispersion step, the fluororesin powder in the mixture 101 is dispersed by mechanical action. Dispersion by mechanical action may include the use of a paint shaker to shake the mixture. After that, in step 3, the dispersed beads are filtered and removed by using a suitable filter 102 (in the example described in the following example section, see the example of such a filter) to form the first fluororesin dispersion liquid 106. Finally, in step 4, the first fluororesin dispersion 106 is dried to form the dry solid fluororesin composition 104 of this example.

The drying process in step 4 can be a continuous drying process with check points during the process to confirm that the mass percentage of the organic solvent in the composition 104 is 0.2% or less. In another example, the drying process may be a process in which the first fluororesin dispersion 106 is dried more than once at the same temperature or fluctuating temperature, and there is a stopping point or a stopping point between the more than one drying. Check points to confirm that the mass percentage of the organic solvent in the composition 104 is 0.2% or less. A solvent of 0.2% or less ensures that the composition 104 is dry enough. The confirmation step at each stopping point or check point to ensure that the mass percentage of the solvent in the composition 104 is 0.2% or less may be: performing a heating process on the composition 104, and determining the composition before and after the heating process The quality of 104 is in the form of verifying that the percentage change in the quality of the composition 104 is 0.2% or less. After the drying process, it is found that the mass percentage change of the composition 104 is 0.2% or less, and it can be concluded that the mass percentage of the solvent in the composition 104 is 0.2% or less.

In the example of forming the composition 104 as shown in Figure 1A, in step 1, each component is added with the following part per mass: 1 to 40 parts by mass of fluororesin; 1 to 10 parts by mass of dispersant; and 50 to 98 parts by mass of the first organic solvent, So that the total parts by mass of the ingredients total 100.

Then, for every 100 parts of the mixture of the fluororesin, the dispersant, and the first organic solvent, 10 to 20 parts by mass of the dispersed beads are added.

FIG. 1B illustrates the steps of preparing a second fluororesin dispersion from the dried solid fluororesin composition 104 manufactured in the example of FIG. 1A. In step A, the second solvent 204 is first added to the dry solid fluororesin composition 104 in FIG. 1A to form a mixture 201. In step B, the mixture 201 is subjected to a redispersion step by mechanical action to redisperse the fluororesin in the mixture 201 to form the second fluororesin dispersion 202.

In the example of manufacturing the second dispersion 202 as shown in Figure 1B, in step A, the components are added in the following parts by mass: 20 to 40 parts by mass of composition 104; and 60 to 80 parts by mass of the second organic solvent, The total mass parts of the composition and the second organic solvent is 100.

The composition 104 in Figure 1A means that the composition includes a fluororesin having an average particle diameter of 1 μm or more and 5 μm or less, and a maximum particle size of 10 μm or less, a dispersant, and a fluororesin having a mass percentage of 0.2% by mass or less of organic solvents or residual organic solvents. The composition 104 of Figure 1A may be in the form of a cake-like material, or more specifically, in the form of a dried or hardened solid block. In another example, the composition 104 in Figure 1A may be in powder form and not aggregate to form a cake-like material.

One of the advantages of the composition 104 of FIG. 1A is that transportation problems can be avoided because harmful organic solvents in the fluororesin dispersion are removed or substantially removed.

Another advantage of the composition 104 in Figure 1A is that it can easily return to the dispersed state again through steps A and B in Figure 1B. The size of the fluororesin powder after redispersion in step B of Fig. 1B is 10 μm or less. Another advantage is that the redispersion of the composition 104 in step A is performed without using dispersing beads. In addition, a suitable but different (different from the first organic solvent) solvent can be used in step A of Figure 1B. The organic solvent used for redispersion of the composition 104 is not limited to the first organic solvent.

One of the applications of the composition according to the example of the present disclosure is to manufacture high frequency circuit boards. Therefore, the fluororesin in the composition 104 in FIG. 1A can be a perfluoro fluororesin with higher dielectric properties. Specifically, the fluororesin may be tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer. Tetrafluoroethylene-hexafluoropropylene (tetrafluoroethylene-hexafluoropropylene) is another choice for fluororesin because it melts during the heating process. Therefore, the fluororesin may be one or two selected from the group consisting of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and tetrafluoroethylene-hexafluoropropylene copolymer.

In another example of the present disclosure, in order to improve the function of the high-frequency circuit board, the fluororesin in the composition 104 in FIG. 1A may contain 10 mol% or less of monomer. For example, fluororesin may contain itaconic anhydride and 5-norbornene-2,3-dicarboxylic anhydride (5-norbornene-2,3-dicarboxylic anhydride) to improve the effect of matrix resin on such high-frequency circuits. Adhesion of the board to the substrate.

According to an example of the present disclosure, the size of the fluororesin powder (after redispersion) in the second fluororesin dispersion 202 in FIG. 1B is 10 μm or less. When it is 10 μm or more, it may have some negative effects on the smoothness of the substrate of the high-frequency circuit board, and may affect the dielectric characteristics of the substrate. This in turn can affect the performance of high-frequency circuits. Especially in a multilayer board with a plurality of laminated substrates, this problem of affecting the performance of the high-frequency circuit becomes significant. In order to obtain a redispersed state of not more than 10 μm, it is required that the average particle diameter in the composition 104 of Fig. 1A is 1 to 5 μm or less, and the maximum particle diameter is 10 μm or less. When the average particle diameter is 1 μm to 5 μm, the amount of the dispersant and the organic solvent used to redisperse the second fluororesin dispersion liquid 202 does not adversely affect the electrical characteristics.

Regarding the organic solvent used in the first fluororesin dispersion 106 in Figure 1A, an example is to use the organic solvent to volatilize under normal pressure or reduced pressure until the mass percentage of the organic solvent in the composition 104 is 0.2% or less. In the case of application to a high-frequency circuit board, an organic solvent is usually used based on the solubility in the matrix resin. Illustrative examples of this organic solvent include MEK (methyl ethyl ketone), toluene, xylene, DMF (dimethylformamide), NMP (NMP (N -Methylpyrrolidone (N-methylpyrrolidone), DMAC (dimethylacetamide), CAN (cyclohexanone) and the like.

As for the dispersant in the composition 104 in Figure 1A, one example is an oligomer of hexafluoropropene. Therefore, the dispersant may be a hexafluoropropylene trimer. The dispersant may contain one or more surfactants. The addition amount of the dispersant varies depending on the organic solvent used, but it can usually be about 1 to 10 parts by mass per 100 parts of fluororesin.

Regarding the dispersion beads used to disperse the first fluororesin dispersion liquid 106 of FIG. 1A, glass, ceramic beads, and oxide beads can be used.

example

Preparation of the dispersion in Example 1 (Ex. 1)

Combine 25 g of tetrafluoroethylene-perfluoroalkylether copolymer (particle diameter D50: 2.1 µm) (fluororesin), and 1 g of hexafluoropropylene trimer surfactant (dispersant) , 75 g of methyl ethyl ketone (MEK) solvent (organic solvent) and 12.5 g of zirconia (Zr) beads (diameter 2 mm) as dispersed beads were added to a 300 ml capacity glass jar. Seal the glass jar with the inner lid and the lid. The sealed glass jar was placed in a paint shaker (Collomix AGIA 200) and shaken for 60 minutes. Then, the mixture in the tank is filtered once through a 185 micron filter screen (an example of the filter 102 in Figure 1A) to remove the zirconia beads. The particle size of the dispersion obtained is determined by a grinder to be less than 10 µm.

Preparation of the dispersion in Example 2 (Ex. 2)

Except for using acetone as the organic solvent instead of MEK, the dispersion was prepared as described in Example 1. The particle size of the dispersion obtained is determined by a grinder to be less than 10 µm.

Preparation of the dispersion in Example 3 (Ex. 3)

This example is intended as a comparative example. A dispersion liquid was prepared as described in Example 1, except that zirconia beads were not added as the dispersion beads. The particle size of the dispersion obtained is determined by a grinder to be greater than 10 µm.

Preparation of the dispersion in Example 4 (Ex. 4)

This example is intended as a comparative example. The dispersion was prepared as described in Example 1, except that the shaking time was 45 minutes instead of 60 minutes. The particle size of the dispersion obtained is determined by a grinder to be greater than 10 µm.

Table 1 shows a summary of the results of Examples 1 to 4. The expected results were found in Examples 1 and 2 (ie, the particle size was less than 10 µm), while Examples 3 and 4 were comparative examples that did not produce the expected results. Table 1. Summary of the results of Examples 1 to 4 example 1 2 3 4 Solvent MEK acetone MEK MEK Surfactant Have Have Have Have Disperse beads Zirconium beads Zirconium beads no Zirconium beads Solvent ratio (that is, the mass of solvent content is higher than the mass of fluororesin content) 3:1 3:1 3:1 3:1 Shaking time 60 minutes 60 minutes 60 minutes 45 minutes Particle size > 10 µm > 10 µm > 10 µm > 10 µm

Preparation of the redispersion in Example I

The dispersion liquid obtained in the above example 1 was exposed to environmental conditions (25° C.) for 7 days to dry, and the glass bottle was not sealed in an exhaust cabinet to obtain a cake-like material. It is confirmed that the cake-like material has been dried by heating the cake-like material and verifying that the mass change percentage of the cake-like material is 0.2% or less. Add 20 g of pastry-like materials and 60 g of acetone to a 300 ml glass jar. The mass of the redispersion solvent is 3:1 compared with the mass of the pastry-like materials. Seal the glass jar with the inner lid and the jar lid. The sealed glass jar was placed in a paint shaker (Collomix AGIA 200) and shaken for 60 minutes. The particle size of the dispersion obtained is determined by a grinder to be less than 10 µm.

Preparation of the redispersion solution in Example II

The redispersion liquid was prepared as described in Example I, except that MEK was used as the redispersion solvent. The particle size of the dispersion obtained is determined by a grinder to be less than 10 µm.

Preparation of the redispersion solution in Example III

Except that the pastry-like material used was obtained by drying from Example 2 and MEK was used as the redispersion solvent, the redispersion liquid was prepared as described in Example 1. The particle size of the dispersion obtained is determined by a grinder to be less than 10 µm.

Preparation of the redispersion solution in Example IV

This example is intended as a comparative example. Except for using dimethylacetamide as the redispersion solvent, the redispersion liquid was prepared as described in Example I. The particle size of the dispersion obtained is determined by a grinder to be greater than 10 µm.

Preparation of the redispersion in Example V

This example is intended as a comparative example. Except for using toluene as the redispersion solvent, the redispersion liquid was prepared as described in Example 1. The particle size of the dispersion obtained is determined by a grinder to be greater than 10 µm.

Preparation of the redispersion solution in Example VI

This example is intended as a comparative example. Except that toluene was used as the redispersion solvent and the mass ratio of the redispersion solvent was increased to 4:1 for the "cake-like material", the redispersion liquid was prepared as described in Example 1. The particle size of the dispersion obtained is determined by a grinder to be greater than 10 µm.

Preparation of the redispersion in Example VII

This example is intended as a comparative example. The redispersion liquid was prepared as described in Example 1, except that toluene was used as the redispersion solvent and the redispersion method used was to stir for 60 minutes with a paint shaker. The particle size of the dispersion obtained is determined by a grinder to be greater than 10 µm.

Table 2 below shows the successful redispersion results by using a redispersion solvent different from the first dispersion solvent. Successful results are defined as redispersion to particle sizes below 10 µm. Examples of successful redispersion were found in Examples I and III, and Examples II and IV to VII are comparative examples. Table 2. Summary of the results of Examples I to VII example I II III IV V VI VII Dry (cake-like) ingredients From Ex. 1 From Ex. 1 From Ex. 2 From Ex. 1 From Ex. 1 From Ex. 1 From Ex. 1 Solvent acetone MEK MEK DMAC Toluene Toluene Toluene Solvent ratio (that is, the mass of solvent content is higher than the mass of dry material) 3:1 3:1 3:1 3:1 3:1 4:1 3:1 Redistribution Paint shaker Paint shaker Paint shaker Paint shaker Paint shaker Paint shaker Paint mixer time 60 minutes 60 minutes 60 minutes 60 minutes 60 minutes 60 minutes 60 minutes Particle size > 10µm > 10µm > 10µm > 10µm > 10µm > 10µm > 10µm

Details of the chemicals used chemical grade manufacturer Tetrafluoroethylene-perfluoroalkyl ether Fluon PW10 AGC Inc. Hexafluoropropylene trimer surfactant Ftergent 710FM Neos Company Limited Zirconia beads 2.0 mm diameter Methyl ethyl ketone (MEK) N, N-Dimethylacetamide (DMAC) Toluene

In the specification and the scope of the patent application, unless the context clearly indicates otherwise, the term "comprising" has the non-exclusive meaning of the word in the sense of "including at least", rather than "comprising only by ...The exclusive meaning in the meaning of "consisting only of". The same logic applies to grammatical changes in other forms of words, such as "comprise", "comprises", etc.

Although the present invention has been described in this disclosure in combination with several embodiments and implementations, the present invention is not limited thereto, but covers various obvious modifications and equivalent arrangements that fall within the scope of the appended patent application. Although the features of the present invention are expressed in certain combinations in the scope of the patent application, it is expected that these features can be arranged in any combination and order.

101,201: Mixture 102: filter 104: composition 106, 202: dispersion 204: second solvent

Figure 1A illustrates the steps of forming the composition according to an example of the present disclosure. Fig. 1B illustrates the steps of producing a fluororesin dispersion from the fluororesin composition of Fig. 1A.

101: Mixture

102: filter

104: composition

106: dispersion

Claims (13)

A dry solid composition comprising: (i) A fluororesin having an average particle diameter of 1 μm or more and 5 μm or less and a maximum particle size of 10 μm or less; (ii) a dispersant; and (iii) an organic solvent, wherein the mass percentage of the organic solvent in the composition is 0.2% or less, The dry solid composition is dried from a first fluororesin dispersion and used for redispersion to form a second fluororesin dispersion. The dry solid composition according to claim 1, wherein the fluororesin is selected from the group consisting of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and tetrafluoroethylene-hexafluoropropylene copolymer. Both. The dry solid composition according to claim 1 or 2, wherein the fluororesin includes 10 mol% or less of a monomer. The dry solid composition according to claim 3, wherein the single system is selected from the group consisting of itaconic anhydride and 5-norbornene-2,3-dicarboxylic anhydride. The dry solid composition according to claim 1 or 2, wherein the dispersant is an oligomer. The dry solid composition according to claim 5, wherein the oligomer is a hexafluoropropylene trimer. The dry solid composition according to claim 1 or 2, wherein the organic solvent is selected from the group consisting of MEK (methyl ethyl ketone) and acetone. The dry solid composition according to claim 1 or 2, wherein the fluororesin composition is in the form of a powder or a cake-like material. A method of manufacturing the dry solid composition according to claim 1 or 2, the method comprising: (i) A mixing step, mixing a fluororesin, a dispersant, an organic solvent and a dispersing aid to form a mixture; (ii) A dispersing step, dispersing the fluororesin in the mixture to form a dispersion; (iii) a filtration step to remove the dispersion aid in the dispersion; and (iv) A drying step, removing the organic solvent in the filtered dispersion so that the mass percentage of the organic solvent in the composition is 0.2% or less. The method according to claim 9, wherein the mixing step includes: (a) Mix the fluororesin, the dispersant and the organic solvent in the following parts by mass: 1 to 40 parts by mass of the fluororesin; 1 to 10 parts by mass of the dispersant; and 50 to 98 parts by mass of the organic solvent, So that the total parts by mass total 100; (b) For every 100 parts of the fluororesin, the dispersant and the organic solvent, add 10 to 20 parts by mass of the dispersion aid. A method of manufacturing a fluororesin dispersion, the method comprising: (i) A mixing step, mixing a second solvent to the fluororesin composition as described in claim 1 or 2 to form a mixture; and (ii) A dispersing step, dispersing the fluororesin in the mixture without using a dispersing aid to form the fluororesin dispersion, The fluororesin in the fluororesin dispersion liquid has an average particle diameter of 1 μm or more and 5 μm or less and a maximum particle size of 10 μm or less. The method according to claim 11, wherein the mixing step includes: 20 to 40 parts by mass of the fluororesin composition and 60 to 80 parts by mass of the second solvent are added so that the total mass parts of the fluororesin composition and the second solvent is 100. The method according to claim 11 or 12, wherein the second solvent is selected from the group consisting of MEK (methyl ethyl ketone) and acetone.

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