WO2011043802A1

WO2011043802A1 - Methods of making solid epoxy resin

Info

Publication number: WO2011043802A1
Application number: PCT/US2010/002683
Authority: WO
Inventors: Leming Gu; Philip J. Carlberg; Bruce D. Hook; Charles L. Menefee; Eric B. Ripplinger; Thomas C. Young; David R. Brooks; David L. Burow; David H. West
Original assignee: Dow Global Technologies Inc.
Priority date: 2009-10-07
Filing date: 2010-10-05
Publication date: 2011-04-14
Also published as: JP2013507481A; EP2486076A1; KR20120112380A; CN102666632A; TW201134845A; BR112012007770A2

Abstract

Methods of making and compositions containing solid epoxy resin in discrete particulate form. The methods include condensing at least one polyphenols compound and at least one condensation compound selected from epichlorohydrin. l,3-dichloro-2-propanol, 2,3-dichloro-2-propanol, epoxy novolacs, and homologs thereof in a single phase homogeneous reaction mixture, where the single phase homogeneous reaction mixture includes a water miscible organic solvent, water, a catalyst, and a dispersant.

Description

METHODS OF MAKING SOLID EP OX Y RESIN

[001] The present disclosure relates to methods for making and compositions containing solid epoxy resin (SER). and in particular methods of making and compositions of SER in discrete particulate form by a condensation reaction.

[002] Epoxy is a thermosetting polymer formed from the reaction of an epoxy "resin" with a polyamine "hardener.'^" Epoxy has a wide, range of applications, including coatings, adhesives, fiber-reinforced plastic materials, composite materials, and electrical laminates. In general, epoxies are known for their adhesion, chemical and heat resistance, mechanical properties and electrical insulating properties.

[003] Commercially produced SER' s have been prepared in a variety of ways, including the condensation of a bisphenol and epichlorohydrin in water. Some approaches use a cellulosic based additive, e.g. , carboxylmethylcellullose sodium salt, to assist forming an epoxy suspension. However, this can lead to the formation of unwanted gel content due to the reactions between epoxides and the multiple primary hydroxyl groups on cellulose molecules. Additional drawbacks of the previous approaches can include residual of unwanted impurities, e.g., chloride ions (CI^") in the SER. Therefore, the SER may need to undergo additional steps after the SER is formed to reduce the impurities to within commercial standards. These additional steps require more time, materials and energy, which increases the cost of production.

[004] "Solid epoxy resin (SER)" refers to an epoxy resin whose physical form is in a solid state at ambient temperature within a range of from 23 decrees Celsius (°C) to 25 °C.

[005] "Discrete particulate form" refers to SER composed of distinct epoxy resin particles, e.g., powder.

[006] "As-made SER" refers to the precipitated SER in discrete particulate form before undergoing additional steps for the reduction of impurities.

[007] "Solution" refers to a polyphenolic compound dissolved in a water miscible organic solvent, water and a catalyst.

[008] "Single phase homogeneous reaction mixture" refers to the solution, a dispersant and a condensation compound in a liquid phase.

[009] "Two phase mixture" refers to the single phase homogeneous reaction mixture in the liquid phase and precipitated SER in a solid phase. [010] "Dispersant" refers to a substance that provides a stable suspension of a condensation compound in the single phase homogeneous reaction mixture.

[011] "Secondary alcohol" refers to an alcohol where the carbon atom to which the hydroxyl group is bonded, is bonded to two carbon atoms.

[012] "Tertiary alcohol" refers to an alcohol where the carbon atom to which the hydroxyl group is bonded, is bonded to three carbon atoms.

[013] "Molecule" refers to the smallest particle of a substance that retains the chemical and physical properties of the substance and is composed of two or more atoms.

[014] "Gel" refers to THF insoluble content and is formed by side reactions between the condensation compound and hydroxyl groups on cellulosic based additives.

[015] The present disclosure provides methods for making a SER in discrete particle form by condensing at least one polyphenolic compound and at least one condensation compound selected from epichlorohydrin, l,3,-dichloro-2-propoanol 2,3-dichloro-2-propanol, epoxy novolacs, and homologs thereof in a single phase homogeneous reaction mixture. The methods produce an as-made SER in discrete particulate form with a CI^" concentration within commercial standards, e.g. , less than or equal to (<) 100 parts per million (ppm) and with no detectable gel, e.g., less than (<) 0.01 wt% of gel.

[016] The methods include forming the solution. The amount of the water miscible organic solvent used in the solution is within a range of from 5 weight percent (wt%) to 20 wt% and preferably within a range of from 10 wt% to 15 wt%, based on the total weight of the single phase homogeneous reaction mixture. The water miscible organic solvent is selected from secondary or tertiary alcohols.

Examples of alcohols include 2-propanol, 2-butanol, t-butanol, 2-methyl-2butuanol. 2-pentanol, 3-pentanol, 2-methyl-2-pentanol, 4-methyl-2-pentanol and combinations thereof. Furthermore, the water miscible organic solvent can be selected from ethers. Examples of ethers include 1 -ethoxy-2-ethanol, l-ethoxy-2-ethanol, l-butoxy-2- ethanol, l-methoxy-2-propanol, l-ethoxy-2-propanol, 1 -isobutoxy-2-propanol, 1- phenoxy-2-propanol, 1 -methoxy-2butanol, 3-methoxy-lbutanol, 2-methoxy-2- methylbutanol, ethylene glycol monoisopropyl ether, ethylene glycol monoisobutyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-tert-butyl ether and combinations thereof. Primary alcohols, or alcohols with more than one primary hydroxyl group per molecule, are not suitable for use as the water miscible solvent, as their reaction with epoxides is unwanted and, in the case of diols, triols or polyols will lead to unwanted gel content.

[017] The catalyst includes substances that are capable of catalyzing the condensation of the polyphenolic compound and the condensation compound.

Catalysts include inorganic compounds. The inorganic compounds are dissolved in water forming an alkaline solution. Examples of inorganic compounds are oxides and hydroxides of metals such as lithium (Li), sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), zinc (Zn) and aluminum (Al). The catalyst is present in an amount that provides a molar ratio of the catalyst to the condensation compound that is within a range of from 0.5: 1 to 10: 1 and more preferably within a range of from 1 : 1 to 1.5: 1.

[018] The polyphenolic compound can be selected from diphenols, e.g. , bisphenols. Examples of bisphenols include bisphenol A, brominated bisphenol A, bisphenol F. bisphenol K, bisphenol S, hydroquinone, resorcinol and 1 ,1- cyclohexanebisphenol. Novolac resins may also be used, either alone or in

combination with one or more bisphenols. Non-phenolic polyhydroxy compounds such as l,4-bis(hydroxymethyl)benzene, l,3-bis(hydroxymethyl)benzene, 1,4- bis(hydroxymethyl)-cyclohexane, 1.3-bis(hydroxymethyl)cyclohexane hexanediol, and cyclohexanediol may also be present in the solution. The amount of the polyphenolic compound used is expressed in a molar ratio basis of the polyphenolic compound to the condensation compound. The molar ratio is within a range of from 1 : 1 to 1 : 10, more preferably within a range of from 1 :1 to 1 :2 and still more preferably within a range of from 1 : 1 to 1 : 1.5.

[019] The methods include adding a dispersant to the solution. The dispersant preferably contains < one hydroxyl group (or groups equivalent thereto) per molecule. The use of a dispersant with < one hydroxyl group per molecule minimizes side reactions between the condensation compound and the hydroxyl groups of the dispersant and forms as-made SER in discrete particulate form with gel within a range of from < 0.18 wt%, more preferably within a range of from < 0.12 wt%, and still more preferably < 0.01 wt%. The dispersant can be selected from methoxypolyethylene glycols (MPEGs). For example, CARBOWAX™ can be used as the dispersant. The MPEGs can have a molecular weight within a range of from 1000 to about 20000, preferably within a range of from 2000 to 10000 and still more preferably within a range of from 2000 to 4000. The dispersant can also be selected from ethylene oxide/propylene oxide di-block copolymers and ethylene

oxide/propylene oxide tri-block copolymers. Mixtures of the various dispersants can also be used. The amount of the dispersant is within a range of from 0.005 wt% to 2 wt%, more preferably within a range of from 0.01 wt% to 1 wt% and still more preferably within a range of from 0.02 wt% to 0.5 wt%, based on the total weight of the dispersant, polyphenolic compound and condensation compound.

[020] The methods include adding at least one condensation compound to the solution and the dispersant to form the single phase homogeneous reaction mixture. The condensation compound is suspended in the single phase homogeneous reaction mixture with the dispersant. The condensation compound can be^' selected from at least one of epichlorohydrin, l,3-dichloro-2-propanol, 2,3-dichloro-2-propanol, epihalohydrin and homologs of these compounds. Other condensation compounds can be used such as diepoxy compounds, e.g., cyclooctene diepoxide, divinylbenzene diepoxide, 1,7-octadiene diepoxide, 1,3-butadiene diepoxide, 1,5-hexadiene diepoxide and the diepoxide of 4-cyclohexenecarboxylate 4-cyclohexenylmethyl ester. Glycidyl ether derivatives of novolacs such as phenol novolac and cresol novolac may also be present. Mixtures of the various condensation compounds can also be used. The total amount of the condensation compound and the polyphenolic compound used in the single phase homogeneous reaction mixture is within a range of from 10 wt% to 90 wt%, preferably within a range of from 30 wt% to about 70 wt% and still more preferably within a range of from 30 wt% to 40 wt%.

[021] The single phase homogeneous reaction mixture may contain one or more additional substances. Examples of such substances include co-dispersants and emulsifiers such as quaternized or hydrophobically modified cellulose ethers. Water soluble polyethylene glycol copolymers, water soluble polyethylene glycols with functional end groups and water soluble polyethylene oxide copolymers are examples. Water insoluble inorganic salts such as, carbonates, phosphates, and sulfates of alkaline earth metals such as calcium phosphate (Ca₃P0₄), magnesium carbonate (MgC0₃), calcium carbonate (CaC0₃), barium carbonate (BaC0₃) and calcium sulfate (CaS0₄) are also examples. Various phase transfer agents may also be added, e.g., benzyl trimethyl ammonium chloride. These substances can be used within a range of from 0.02 wt% to 2 wt%, preferably within a range of from 0.02 wt% to 1 wt% and more preferably within a range of from 0.02 wt% to about 0.05 wt%, based on the total weight of the additional substances, polyphenolic compound, dispersant, and condensation compound.

[022] For the methods described above, the reaction temperature is within a range of from 30 °C to 150 °C, more preferably within a range of from 40 °C to 150 °C and still more preferably within a range of from 70 °C to 150 °C. The methods of this disclosure are performed at 1 standard atmosphere (atm) (101.3 kilopascal), but other pressures may be used, e.g. , up to 5 atm, or under vacuum.

[023] The as-made SER is precipitated from the single phase homogeneous reaction mixture and the single phase homogeneous reaction mixture becomes a two phase mixture. The as-made SER in discrete particulate form can be separated from the two phase reaction mixture by standard techniques, such as filtration, washing, neutralizing and drying. An example of a neutralizing agent for neutralizing excess catalyst is a 25 wt% sodium hypophosphate (NaH₂P0₄) solution.

[024] The as-made SER has a CI^" concentration of < 150 ppm and more preferably < 100 ppm, with no detectable gel. Greater than or equal to (>) 98 % of the particles of the as-made SER in discrete particulate form have a particle diameter size that is within a range of 10 micrometer (μηι) to 1000 μη . Advantageously, some particles are within a range of from 20 μηι to 900 μηα with a preferred size of < 800 μηι. The average particle size is within a range of from 10 μπι to 500 μπι.

Advantageously, the average particle size is within a range of from 50 μπι to 300 μηι and still more preferably < 200 μπι can also be achieved.

[025] The as-made SER in discrete particulate form has a number average molecular weight (Mn) within a range of from 1000 to 5000, preferably within a range of from 1800 to 4000, and still more preferably within a range of from 2000 to 3000. The weight average molecular weight (Mw) of the as-made SER in discrete particulate form is within a range of from 2000 to 9000, more preferably within a range of from 3500 to 7000 and still more preferably within a range of from 4500 to 6400. Molecular weight is a dimensionless number even though sometimes expressed in terms of Daltons or grams per mole.

Example (Ex) 1 (Comparative) [026] To a 1 Liter (L) round bottom flask equipped with an overhead stirring apparatus, a cooling condenser and a heating mantle, add 310 grams (g) of deionized water, 40 g 2-propanol (CAS# 67-63-0), 30.8 g of 50 wt% NaOH aqueous solution and 64.1 g of Bisphenol A (CAS# 80-05-7) to form a solution. Heat the solution to 40 °C while agitating at 570 revolutions per minute (rpm), under a continuous nitrogen purge. After the Bisphenol A completely dissolves, add 0.24 g of MPEG 2000 (Carbowax™, available from The Dow Chemical Company) to the solution. Agitate the flask contents for 5 minutes (min.) and then add 32.5 g of epichlorohydrin to the solution to form the single phase homogeneous reaction mixture. Heat the single phase homogeneous reaction mixture to 50 °C while stirring and once the flask contents turns turbid, add 0.09 g of cationic hydroxylethyl cellulose (CAS # 9004-65- 3) and 10 g of deionized water. Heat the two phase reaction mixture to 88 °C and maintain that temperature for 120 min.

[027] During the 120 minutes, take samples and test the phenolic OH concentration in the two phase reaction mixture. Once the phenolic OH concentration is < 500 ppm, cool the two phase reaction mixture to 40 °C, then drain the flask of its contents, and wash the flask with 800 g deionized water three times, adding the wash to the flask contents. Neutralize excess NaOH in the as-made SER in discrete particulate form with 25 wt% NaH₂P0 aqueous solution. Separate the as-made SER by filtration and vacuum dry at 20 °C for 10 hours. The resulting as-made SER is a fine white powder and has an average phenolic OH of 630 ppm, an average particle size of 71 μ^ηι and molecular weights of Mn=1710 and Μ_\ν=3130. The CI^" concentration in the as-made SER is 540 ppm. There is no detectable gel content. Ex 2 (Comparative)

[028] Repeat Ex 1 with the following changes. For the solution, change the amount of the 50% NaOH aqueous solution to 27.4 g. Replace the MPEG 2000 with MPEG 4000 in the same amount. For the single phase homogeneous reaction mixture, change the amount of epichlorohydrin to 29.1 g and change the amount of 1 wt% cationic hydroxylethyl cellulose aqueous solution to 3 g. Heat the two phase reaction mixture to 88 °C for 180 min. The resulting as-made SER has a phenolic OH concentration of 1190 ppm, an average particle size of 255 ,um and molecular weights of Mn=3010 and Mw=6070. The CI^" concentration in the as-made SER is 2880 ppm. The gel content is 0.12 wt%. Ex 3

[029] Repeat Ex 1 with the following changes. For the solution, change the amount of the 50 wt% NaOH aqueous solution to 37.0 g. Replace the MPEG 2000 with MPEG 4000 in the same amount. For the single phase homogeneous reaction mixture, change the amount of epichlorohydrin to 39.0 g and change the amount of the 1 wt% cationic hydroxylethyl cellulose aqueous solution to 3 g. Heat the two phase reaction mixture to 70 °C for 135 min. The resulting as-made SER has a phenolic OH concentration of 370 ppm, an average particle size of 255 μηι and molecular weights of Mn=940 and Mw=1650. The CI^" concentration in the as-made SER is 55 ppm. There is no detectable gel content.

Ex 4

[030] Repeat Ex 2 with the following changes. For the solution, change the amount of 2-propanol to 60.0 g. For the single phase homogeneous reaction mixture, change the amount of 1 wt% cationic hydroxylethyl cellulose aqueous solution to 1.5 g. Heat the two phase reaction mixture to 88 °C for 180 minutes. The resulting as- made SER in discrete particulate form has a phenolic OH concentration of 1 190 ppm, an average particle size of 227 μηι and molecular weights of Mn=2900 and

Mw=6240. The CI^" concentration in the as-made SER in discrete particulate form is 74 ppm.

Ex 5

[031] Repeat Ex 1 with the following changes. For the solution, change the amount of 2-propanol to 50 g. Replace the MPEG 2000 with MPEG 4000. For the single phase homogeneous reaction mixture, change the amount of 1 wt% cationic hydroxylethyl cellulose aqueous solution to 1.5 g. Heat the reaction mixture to 88 °C for 180 minutes. The resulting as-made SER has a phenolic OH concentration of 610 ppm, an average particle size of 220 μπι and molecular weights of Mn=1800 and Mw=3340. The CI^" concentration in the as-made SER in discrete particulate form is 120 ppm.

Ex 6 (Comparative)

[032] Repeat Ex 1 with the following changes. Combine 250.0 g of deionized water, 30.8 g of 50 wt% NaOH aqueous solution and 64.1 g of Bisphenol A. 2-propanol is not used in this example. Heat the flask contents to 50 °C. After the Bisphenol A completely dissolves, cool the flask contents to 40 °C, and add 75.0 g of 0.33 wt% hydroxypropylmethylcellulose aqueous solution (Methocel® F75M, The Dow Chemical Company) to the flask contents. Add 32.5 g of epichlorohydrin to the flask contents. Heat the flask contents to 95 °C while stirring and maintain that temperature for 65 minutes. Cool flask contents to 70 °C. then drain the flask of its contents, and wash the flask with 350 g of deionized water 3 times. The resulting as- made SER in discrete particulate form has a phenolic OH concentration of 1860 ppm, an average particle size of 254 μηι and molecular weights of Mn=1670 and

Mw=3120. The CI^" concentration in the as-made SER in discrete particulate form is 5750ppm. The gel content is 5.3 wt%.

Test Methods

[033] Track the phenolic OH concentration by a Shimadzu UV1201 UV-

Visspectrophotometer. Measure the CF concentration according to ASTM D512-04 with a modification of dissolving the as-made SER in discrete particulate form in acetone and performing a silver nitrate titration with methanol. Measure gel content by drying and weighing the gel residue and taking a ratio of the weight of the gel to the weight of the initial sample. Measure particle size with a Beckman Coulter dynamic image analyzer with RapidVue 2.006 software.

Claims

Claims What is claimed:

1. A method of making solid epoxy resin in discrete particulate form comprising, condensing at least one polyphenolic compound and at least one condensation compound selected from epichlorohydrin, l,3-dichloro-2-propanol, 2,3,-dichloro-l- propanol, epoxy novolacs and homologs thereof in a single phase homogeneous reaction mixture, where the single phase homogeneous reaction mixture includes a water miscible organic solvent, water, a catalyst, and a dispersant.

2. The method of claim 1. where the single phase homogeneous reaction mixture becomes a two phase mixture when the solid epoxy resin precipitates from the single phase homogeneous reaction mixture.

3. The method of claim 1. including selecting the water miscible organic solvent from the group consisting of secondary alcohols, tertiary alcohols, ethers and combinations thereof.

4. The method of any of the preceding claims, where the water miscible organic solvent is 2-propanol.

5. The method of any one of the preceding claims, where the dispersant is a methoxypolyethylene glycol.

6. The method of claim 1, where the method further includes carrying out the condensation in the presence of a co-dispersant that includes a modified cellulose ether.

7. The method of any one of the preceding claims, where the solution includes 20 weight percent or less of the water miscible organic solvent based on the total weight of the single phase homogeneous reaction mixture.

8. The method of any one of the preceding claims, where the dispersant contains one or less than one hydroxyl group per molecule.

9. A solid epoxy resin in a discrete particulate form formed from the method of claim 1, where the concentration of chloride ions in the solid epoxy resin in discrete particulate form is less than or equal to 150 parts per million and less than 0.01 weight percent gel.