WO2019232147A1

WO2019232147A1 - Novolac resins, methods of making, and uses in rubber compositions

Info

Publication number: WO2019232147A1
Application number: PCT/US2019/034549
Authority: WO
Inventors: Michael C. Walkup; Toshiaka MIYATAKE; Tamon Itahashi; Koichiro Tajima
Original assignee: Sumitomo Chemical Co Ltd; Sumika Electronic Materials Inc; Sumitomo Chemical Advanced Technologies LLC
Current assignee: Sumitomo Chemical Co Ltd; Sumika Electronic Materials Inc; Sumitomo Chemical Advanced Technologies LLC
Priority date: 2018-05-31
Filing date: 2019-05-30
Publication date: 2019-12-05
Anticipated expiration: 2020-11-30

Abstract

A solid RF (novolac) resin comprises reacting a resorcinolic compound and an aldehyde or ketone in the presence of an organic solvent, such as methyl isobutyl ketone, and water. The resultant solid RF resin may be characterized as having less than 2 wt.% water, less than 2 wt. % free (unreacted) resorcinol, and greater than 65 mole % 4,4'-linkage content.

Description

NOVOLAC RESINS, METHODS OF MAKING, AND USES IN RUBBER COMPOSITIONS

CROSS-REFERENCE TO RELATED APPLICATIONS

[001] This application claimed the benefit of ETS Provisional Patent Application No. 62/678,496, filed May 31, 2018, the disclosure of which is hereby incorporated by reference.

FIELD OF THE INVENTION

[002] Embodiments of the present invention provide unique solid resorcinolic- formaldehyde resins and methods for making the same. Other embodiments are directed toward the use of these solid resorcinolic-formaldehyde resins in vulcanizable rubber compositions.

BRIEF DESCRIPTION OF THE PRIOR ART

[003] Resorcinol-formaldehyde resins, also referred to as RF resins or novolac resins, are the reaction product of resorcinol and formaldehyde (or any aldehyde or ketone) in the presence of excess resorcinol. These resins have many uses including use as an adhesive in rubber. In this paper, the term“resorcinolic resins” is also used to convey these same resins, with the understanding that such resins can also be made with aldehydes or ketones other than formaldehyde, and with modified resorcinolic compounds other than resorcinol per se.

[004] Solid RF resins may be used to enhance rubber properties. In this use, the solid RF resin can be compounded with rubber. The solid RF resins are typically obtained by isolating the resin from the reaction mixture, which mixture includes water that results from the reaction (i.e. condensation reaction). Typically, the reaction occurs as the water is refluxed at or around l00°C. Additionally, these RF resins may be used to coat fabrics that are used as rubber reinforcements to thereby increase the compatibility between the rubber and the fabric. The fabrics are typically treated by dipping or otherwise coating the fabric with an aqueous latex suspension containing the RF resin, which compositions are also referred to as an RFL dip.

[005] Resorcinolic resins are often produced with excess resorcinol; i.e. the resins generally have 10 to 20% unreacted or free resorcinol. The amount of free resorcinol can be a critical factor when balancing important properties. For example, if the amount of free resorcinol is reduced, which can be accomplished by increasing the relative amount of aldehyde, the softening point of the resin is increased which thereby creates difficulty when compounding with rubber at conventional compounding temperatures.

[006] The presence of free resorcinol, however, can be problematic. For example, free resorcinol can volatilize during rubber mixing, such volatilization is often referred to as fuming, and thereby creates added issues to the rubber mixing process. Further, the presence of the free resorcinol contributes to the hygroscopicity of the resorcinolic resin, which in turn creates storage and handling problems.

[007] Efforts have been made to reduce the amount of free resorcinol within these RF resins by modifying or adding substituents to the resorcinol during the manufacture of the resin. This modification reduces the amount of free resorcinol available for fuming, but also reduces the number of reactive sites on the resorcinol molecule from three positions (2, 4, and 6) to two or less. The modified resorcinolic resin is also less likely to absorb moisture. Thus, by modifying the resorcinol, RF resins having low fuming and low hygroscopicity have been produced. These modified compounds, which are often referred to as styrenated resorcinolic resins, are conventionally produced by employing modified resorcinolic compounds that are formed by reacting styrene with resorcinol at a molar ratio of about 0.4: 1. For example, U.S. Pat. No. 5,049,641 teaches the synthesis of resorcinolic resins using modified resorcinol that is formed by reacting styrene with resorcinol at a molar ratio of at least 0.25: 1. Related thereto, U.S. Patent No. 5,021,522 teaches improved vulcanizable rubber compositions prepared with aralkylated phenolic resins that are used as methylene acceptors.

[008] Also, when free resorcinol is reduced by styrenation, the resulting resin often has lower reactivity, and the resin softening point may be affected, causing difficulty in use, that is, too high to mix with the rubber or too low to handle easily. Therefore, it is necessary to balance the competing factors of free resorcinol, reactivity and softening point.

SUMMARY OF THE INVENTION

[009] Aspects of the present invention provide a process for making a solid resorcinolic resin comprising the steps of forming a mixture including a resorcinolic compound, water, an organic solvent, and, optionally, an acid catalyst; adding an aldehyde to the mixture to thereby react the aldehyde with the resorcinolic compound and form a reaction mixture including a resorcinolic resin, unreacted resorcinolic compound, the organic solvent, and water; substantially removing the water from the reaction mixture to thereby produce an organic composition containing the resorcinolic resin, the organic solvent, and optionally unreacted resorcinolic compound; and removing the organic solvent from the organic composition to provide the solid resorcinolic resin.

[0010] In some embodiments, the unreacted resorcinolic compound includes free resorcinol and, in the step of substantially removing water, the water substantially lowers the amount of the free resorcinol remaining in the organic composition produced from the reaction mixture. It will be appreciated that some water and some unreacted resorcinolic compound will remain in the solid resorcinolic resin, but much lower amounts, essentially de minimus amounts, of free resorcinol will remain in the resultant solid RF resins. In some other embodiments, the resorcinolic compound includes an aralkyl-substituted resorcinol, wherein the unreacted resorcinolic compound includes aralkyl-substituted resorcinol, and where the solid resorcinolic resin includes aralkyl-substituted resorcinol. In still other embodiments, the step of providing includes the step of reacting resorcinol with styrene monomer to form a styrenated resorcinol. Accordingly, in at least one embodiment, the resorcinolic compound is a styrenated resorcinol.

[0011] In at least one embodiment, the reaction mixture is maintained at a temperature of less than 80 °C. In other embodiments, the temperature may be less than 60 °C, in other embodiments, the temperature may be less than 50 °C, and in other embodiments, less than 45 °C prior to the step of substantially removing water

[0012] In some embodiments, the process further includes the step of adding an aldehyde to the reaction mixture. In other embodiments, the process further includes the step of maintaining the reaction mixture under reaction conditions prior to said step of substantially removing the water, where said step of maintaining extends for greater than 15 minutes, preferably greater than 30 minutes, and more preferably, greater than 60 minutes, and where the reaction mixture is maintained at a temperature of less than 80 °C, preferably less than 60 °C, preferably less than 50 °C, and more preferably, less than 45 °C prior to said step of substantially removing water.

[0013] In some embodiments, the organic solvent is selected from the group consisting of methyl isobutyl ketone (MIBK), methyl tert-butyl ether, cyclopentyl methyl ether, and ethyl acetate. In some embodiments, the acid catalyst is selected from the group consisting of inorganic acids, heteropoly acids, and combinations thereof. In some embodiments, the acid catalyst is selected from the group consisting of phosphoric acid, sulfuric acid, hydrochloric acid, phosphotungstic acid, phosphomolybdic acid, and silicomolybdic acid. In some embodiments, the aldehyde is formaldehyde. In some embodiments, the mixture includes greater than 25 parts by weight organic solvent and greater than 25 parts by weight water per 100 parts by weight resorcinolic compound. In some embodiments, the mixture includes greater than 25 parts by weight organic solvent and greater than 25 parts by weight water per 100 parts by weight resorcinolic compound.

[0014] In some embodiments the process step of adding aldehyde includes adding an aqueous solution including an aldehyde. It will be appreciated that, in at least one embodiment of the process, the step of subsequently mixing the aldehyde includes the step of reacting the aldehyde and the resorcinolic compound in the presence of water and the organic solvent at a reaction temperature less than 80°C, such that a two-phase system is provided. The two-phase system includes a first phase generally containing the organic solvent and the formed resorcinolic resin. More particularly, the first phase is provided by the reaction of the resorcinol and aldehyde, wherein the resorcinolic resin is generally formed (e.g., dissolved or solvated) within the organic solvent. The second phase generally includes the water and unreacted, unsubstituted resorcinol (i.e., free resorcinol), most of which is dissolved or solvated in the water.

[0015] In some embodiments, the step of substantially removing water removes greater than 75 wt %, preferably 85 wt %, preferably 90 wt %, preferably 95 wt %, and preferably 97 wt % of any free resorcinol within the reaction mixture.

[0016] In some embodiments, the process further includes the step of washing the solvent- containing composition to remove unreacted resorcinolic compound.

[0017] In some embodiments, the molar ratio of aldehyde to resorcinolic compound is less than 1 : 1. In some embodiments, the solid resorcinolic resin includes less than 2 wt %, preferably less than 1 wt %, preferably less than 0.5 wt %, and preferably less than 0.25 wt % free resorcinol. In some embodiments, the solid resorcinolic resin comprises greater than 60 mol%, and preferably, greater than 65 mol% 4,4’ -linkage content. In some embodiments, the solid resorcinolic resin has a pentamer or higher oligomer content of less than 55% according to GPC using a polystyrene standard. .

[0018] Other aspects of the present invention are provided in a solid resorcinolic resin formed by the reaction of a resorcinolic compound with formaldehyde in the presence of water, methyl isobutyl ketone and, optionally, a catalyst selected from phosphoric acid or sulfuric acid, the solid resorcinolic resin comprising a resin including units defined by the formula (I)

where Rl is a hydrogen atom or an aralkyl group, at least one of R2 and R3 is an alkylene bridge, and the other of R2 and R3 is an alkylene bridge or a hydrogen atom; and includes less than 2 wt.% water and has greater than 60 mol % 4,4'-linkage content. In some embodiments, the solid resorcinolic resin will have a pentamer or higher oligomer content of less than 55%. In some embodiments, the solid resorcinolic resin will have less than 2 wt.% free resorcinol remaining in the resin. In some embodiments, the solid resorcinolic resin will have a lower softening point as compared to conventional solid resorcinolic resins prepared with a resorcinolic compound reacted with formaldehyde in the presence of water and a p-toluene sulfonic acid catalyst without any organic solvent present. In some embodiments, the solid resorcinolic resin will have less than 0.5 wt.% water. In some embodiments, the solid resorcinolic resin will have a Mw of greater than 600 and less than 1500 g/mol.

[0019] Other aspects of the invention provide a vulcanizable rubber composition comprising a vulcanizable rubber; a curative; and a solid resorcinolic resin prepared by the process above, wherein the solid resorcinolic resin includes less than 2 wt.% water, and has greater than 60 mole % 4,4'-linkage content. In one or more embodiments, less than 1 wt. % free resorcinol remains. In other embodiments, less than 0.5 wt. % free resorcinol remains, and in still other embodiments, less than 0.25 wt. % free resorcinol remains. Likewise, in some embodiments, less than 1 wt. % water remains. In other embodiments, less than 0.5 wt. % water remains, and in still other embodiments, less than 0.25 wt. % water remains.

[0020] Other aspects of the invention are provided by vulcanizable rubber compositions prepared as described above. Advantageously, in some embodiments, the vulcanizable rubber compositions includes a resorcinolic resin having a softening point lower than conventionally prepared resorcinolic resins, but the vulcanizable composition, when vulcanized, unexpectedly has a cure time (T’90) essentially the same as the vulcanizable rubber composition prepared with conventional resorcinolic resins. Also, in some embodiments, the vulcanizable rubber compositions, when vulcanized, exhibit better adhesion as determined by unaged pull force, then vulcanized compositions containing conventional resorcinolic resins.

[0021] Furthermore, and advantageously, will be appreciated that solid resorcinolic resins made according to the concepts of the present invention can be made at lower temperatures using an organic solvent such as methyl isobutyl ketone (MIBK), wherein the resultant solid resorcinolic resins exhibit less water in them that conventional products, exhibit less free resorcinol in them than conventional products, and exhibit a lower softening point than conventional products, all without affecting cure times upon vulcanization.

DETAILED DESCRIPTION

[0022] The present invention is based, at least in part, on the discovery of a process for preparing a solid resorcinolic-formaldehyde (RF) resin having relatively high 4,4'-linkage content microstructure, a relatively low molecular weight correlating to a relatively low pentamer and higher oligomer content, a low water content, and/or a low free resorcinol content. When compounded into vulcanizable rubber compositions, these solid RF resins have given rise to unexpected results including, among other things, improvements in one or more of cure speed, mechanical properties of the cured rubber (e.g. cord pull-out strength), and dynamic properties of the cured rubber (e.g. higher G’). Additionally, while the solid resins of the prior art generally show direct relationships between free resorcinol and cure speed (i.e. the higher the free resorcinol, the faster the cure speed), the resins of one or more embodiments advantageously provide relatively fast cure speeds at very low levels of free resorcinol.

[0023] The present invention is able to provide this unique resorcinolic-formaldehyde resin by providing a new process for the preparation thereof. The new process is unique in that it combines the resorcinolic compound and aldehyde in the presence of both water and an organic solvent, with the understanding that the organic solvent is provided prior to the addition of the aldehyde so that the reaction of the resorcinolic compound and aldehyde can take place at temperatures (e.g., less than 80°C, and for formaldehyde, at about 40°C) well below what is typically used (e.g., refluxed at l00°C) for such reactions. Furthermore, it is believed that, because the organic composition formed as a result the reaction of the resorcinolic compound and aldehyde is solvated in the organic solvent, substantial amounts of free resorcinol are solvated in the water layer, meaning as the water layer is substantially removed, the amount of free resorcinol remaining in the organic composition is substantially lower. However, it has been found that the resultant solid resin, once the solvent is removed, has very low water content and very low free resorcinol content, while still providing essentially the same or better properties when used to prepare a rubber vulcanizable composition.

Resin Composition

[0024] The resorcinolic-formaldehyde (RF) resins prepared according to the present invention include two or more resorcinol groups bonded through respective methylene bridges. As the skilled person appreciates, the methylene bridge can bond to the resorcinol unit or group at the 2, 4, and 6 position of the resorcinol group (i.e. on the ring).

[0025] As suggested above, aspects of the invention benefit from the solid nature of the RF resins. Accordingly, the RF resins of the present invention can be characterized by the absence of or limited amounts of water present within the resorcinolic resin. In one or more embodiments, the solid RF resins of the present invention include less than 3 wt.%, in other embodiments less than 2 wt.%, in other embodiments less than 1 wt.%, in other embodiments less than 0.5 wt.%, in other embodiments less than 0.25 wt.%, and in other embodiments less than 0.10 wt.% water relative to the total weight of the solid resin. In one or more embodiments, the RF resins of the present invention are substantially devoid of water, which refers to that amount of water or less that would otherwise have an appreciable impact on the resins or their use. In particular embodiments, the RF resins of the present invention are devoid of water. As the skilled person appreciates, the amount of water in the resin can be determined by a variety of methods including, but not limited to, Karl Fischer titration methods. In particular embodiments, the amount of water is determined using a modified version of ASTM E 203, where the method is modified by replacing the injection septum with a stopper and the pulverized resin is added through this port.

[0026] The solid RF resins of the present invention are characterized by a relatively high 4,4'-linkage content. As the skilled person appreciates, this linkage content refers to the location of the methylene units bonded to the neighboring resorcinolic units. As shown in the following formula, the methylene units (also referred to as methylene bridges) are shown at the 4 and 4' positions on the neighboring resorcinolic units.

[0027] The 4,4'-linkage content can be described as a mole percent, which refers to the moles of resorcinolic units, relative to the total moles of the resorcinolic units within a particular sample, that include the 4,4'4inkage microstructure. The mole percentage can be determined experimentally by employing known techniques, such as nuclear magnetic resonance (NMR). In one or more embodiments, the solid RF resins of the present invention are characterized by including greater than 60 mole %, in other embodiments greater than 65 mole %, in other embodiments greater than 70 mole %, and in other embodiments greater than 75 mole %, 4,4'- linkage content. In one or more embodiments, the solid RF resins of the present invention are characterized by including from about 60 to about 100 mole %, in other embodiments from about 60 to about 95 mole %, in other embodiments from about 60 to about 90 mole %, and in other embodiments from about 65 to about 85 mole % 4,4'-linkage content.

[0028] It will be appreciated that the higher 4,4’-linkage content is attributable to the fact that most, if not all, of the water in the process of producing the RF resin is removed. Due to the two phase system used in the present invention, most, if not all, of the unreacted resorcinol that would remain in the solid RF resin is removed with the water, as the unreacted resorcinol is generally dissolved or solvated with the water, while the solid RF resin is generally dissolved or solvated in the organic solvent.

[0029] The solid RF resins of the present invention are characterized by a low molecular weight. As the skilled person will appreciate, the molecular weight of RF resins can be determined using several methodologies, and the molecular weight is typically reported in terms of weight average molecular weight (Mw) or number average molecular weight (Mn). Useful techniques for determining the molecular weight of solid RF resins include gel permeation chromatography using polystyrene standards (GPC) or vapor phase osmometry. [0030] In one or more embodiments, the solid RF resin compositions of the present invention may be characterized by weight average molecular weight (Mw), which may be determined by GPC using a polystyrene standard. In one or more embodiments, the Mw of the resin is greater than 600, in other embodiments greater than 700, in other embodiments greater than 800, in other embodiments greater than 900, and in other embodiments greater than 1000 g/mole. In these or other embodiments, the Mw of the resin is less than 1500, in other embodiments less than 1400, in other embodiments less than 1250, in other embodiments less than 1200, and in other embodiments less than 1150 g/mole. In these or other embodiments, the solid RF resin of the present invention may be characterized by a Mw that is from about 600 to about 1500, in other embodiments from about 800 to about 1500, and in other embodiments from about 1000 to about 1500 g/mole.

[0031] In correlation to the molecular weight, the solid RF resin compositions of the present invention also are characterized as having a low pentamer or higher oligomer content. This can be expressed in several ways. However, the first of two approaches used for this invention provide for a comparison of pentamer or higher oligomer content via GPC using a polystyrene standard. Generally, a pentamer or higher oligomer is considered under GPC analysis to be any oligomer found to have a weight average molecular weight of more than 1000 g/mol. Generally, the amount of pentamer or higher oligomer content in the solid RF resins of the present invention is less than 55%. Moreover, when compared to conventional RF resins having a like amount of resorcinol, the pentamer content is well below that the conventional RF resins, typically by more than 10%.

[0032] The second approach is to provide a ratio of dimer and trimer to tetramer and pentamer and higher oligomers. Compared to conventional RF resin, the dimer and trimer to tetramer and pentamer ratio is 50% or higher.

[0033] In one or more embodiments, the solid RF resin compositions of the present invention may be characterized by a softening point that is greater than 90°C, in other embodiments greater than l00°C, in other embodiments greater than H0°C, and in other embodiments greater than l20°C. In these or other embodiments, the solid RF resin of the present invention may be characterized by a softening point that is from about 90°C to about 140 °C, in other embodiments from about 95°C to about 135 °C, and in other embodiments from about l00°C to about l30°C. The softening point of the resins can be determined according to the following method with reference to the latest edition of ASTM E 28 and ASTM D 6090, which are incorporated by reference herein in their entirety. This method can employ a Mettler softening point apparatus, which may include a control unit Model FP-90 or equivalent, a furnace Model FP-83 or equivalent, and cartridge assemblies, a timer, porcelain evaporating dishes (about 3” in diameter), and a hot plate. The method may employ cups of pitch type drilled to 0.257” opening (F drill), and a 440 stainless steel ball (0.2500” in diameter and must pass through cups). The apparatus may be calibrated according to ASTM D 6090. A resin sample (-15 grams) can be melted in a porcelain or aluminum evaporating dish on the surface of a hot plate at 600 - 650 °F, for approximately 4 minutes. After melting, the sample can be poured into cups that had been preheated to at least the temperature of the molten resin. The quantity of resin sample poured into the cups should be such that after solidification, the excess can be removed with a heated spatula or putty knife. The sample can then be cooled to room temperature in a desiccator, the cartridge can then be assembled so that the ball rests on the top of the resin. The assembled cartridge is then placed in the furnace, which can be preset to 85 °C or 10-15 °C below the expected softening point. The heating rate can be set at 1 °C/min. The cartridge can then be turned until it is locked into position. After 30 seconds, the operation of softening point apparatus can be initiated, thereby yielding the completed softening point measurement.

[0034] As suggested above, the RF resins of the present invention can be characterized by low levels of free resorcinol, which refers to the amount of unreacted, unsubstituted resorcinol remaining with the resin. In this context,“free resorcinol” refers to resorcinol not reacted with the aldehyde in the RF resin and that remains free of any other substituents. This is to be distinguished from the term“resorcinolic compound” that includes both free resorcinol and aralkyl-substituted resorcinol, such as styrenated resorcinol, as described above. Essentially any resorcinol or substituted resorcinol compound used prior to the reaction with aldehyde will be included in the term“resorcinolic compound.” In contrast,“free resorcinol” it essentially limited to only unsubstituted resorcinol that remains unreacted in the reaction mixture.

[0035] In one or more embodiments, the solid RF resins of the present invention include less than 3 wt.%, in other embodiments less than 2 wt.%, in other embodiments less than 1 wt.%, in other embodiments less than 0.5 wt.%, in other embodiments less than 0.25 wt.%, and in other embodiments less than 0.10 wt.% free resorcinol relative to the total weight of the solid resin. In one or more embodiments, the RF resins of the present invention are substantially devoid of free resorcinol, which refers to that amount of resorcinol or less that would otherwise have an appreciable impact on the resins or their use. In particular embodiments, the RF resins of the present invention are devoid of free resorcinol. As the skilled person appreciates, the amount of free resorcinol (i.e. unreacted, unsubstituted resorcinolic compounds not bound within the solid RF resin) can be determined by liquid chromatography. The term“resorcinolic compound” has been used to include not only unsubstituted resorcinol, but also to include aralkyl-substituted resorcinol, such as styrenated resorcinol.

Preparation of RF Resin

[0036] In one or more embodiments, the RF resins of the present invention are generally prepared by reacting a resorcinolic compound with an aldehyde or ketone in the presence of an organic solvent and water. As the skilled person appreciates, and as noted above, resorcinolic compounds include, but are not limited to, resorcinol, which is also referred to as dihydric phenol or 1, 3-dihydroxy benzene, or free resorcinol. Generally, resorcinolic compounds also include aralkyl-substituted resorcinol, which include styrene-substituted resorcinol produced by charging resorcinol and heating it to 120 °C - 135 °C, adding a standard catalyst such as p-toluene sulfonic acid to the resorcinol, and then reacting styrene, typically stream-wise, over a period of about 15 to 100 minutes while the temperature was maintained at 120 °C - 135 °C. After adding all of the styrene, the temperature may then be increased to 150 °C - 155 °C and maintained at 150 °C - 155 °C for at least another 15 minutes.

[0037] Once the desired resorcinolic compound is produced, water, an organic solvent, and, optionally, a catalyst made be charged to form a mixture with the resorcinolic compound. Subsequently, aldehyde may then be charged (typically stream-wise) to the mixture at a temperature less than 80°C, (for formaldehyde, about 40 °C) over a period, in at least one embodiment, of at least 15 minutes, in another embodiment, at least 30 minutes, and in another embodiment, at least 60 minutes. In one or more embodiments, the aldehyde may be added over a period of about 15 to 90 minutes. After all of the aldehyde was charged, the reaction mixture was maintained at a temperature less than 80°C, and more preferably, at about 40°C for, in at least one embodiment, for a period greater than 15 minutes. In other embodiments the reaction may be maintained at less than 80°C, and for formaldehyde, about 40°C, for a period greater than 30 minutes, and in another embodiment for a period greater than 60 minutes. In other embodiments, the reaction may be maintained for between 15 minutes to 2 hours. Afterward, the water layer is substantially removed, and the organic layer was washed several times with water. Then, sodium hydroxide solution may be added. The organic solvent is then removed, as for example, by vacuum distillation to 155 °C. Generally, when a temperature of 155 °C was reached, the vacuum can be released and the resultant solid RF resin can be obtained.

[0038] The molar ratio of aldehyde or ketone to resorcinol is less than 1 : 1. In other embodiments, less than 0.8: 1, and in other embodiments, less than 0.7: 1. In some embodiments, the molar ratio of aldehyde/ketone to resorcinol may vary from about 0.50: 1 to 1 : 1, in other embodiments from about 0.52: 1 to about 0.80: 1, in other embodiments from about 0.54: 1 to about 0.76: 1, in other embodiments from about 0.56: 1 to 0.72: 1, and in other embodiments from about 0.57: 1 to about 0.70: 1. The skilled person appreciates that the conventional ingredients for forming RF resins include resorcinol and formaldehyde. Accordingly, reference within the specification has been made to resorcinol and formaldehyde, as well as RF resins. The skilled person will appreciate, however, that these teachings can be extended to various resorcinolic compounds and to various aldehydes or ketones without undue experimentation or calculation. Stated differently, reference to resorcinol and formaldehyde, as well as RF resins, is made for convenience, but does not limit the scope or applicability of the inventions described herein. Further, the term“resorcinolic resin” is used interchangeably herein with“RF resins.”

[0039] In one or more embodiments, the aldehyde or ketone may be selected from the group consisting of formaldehyde, methyl formed, acetaldehyde, propionaldehyde, butyraldehyde, crotonaldehyde, cinnamaldehyde, benzaldehyde, furfural, acetone, and methyl ethyl ketone. In particular embodiments, the aldehyde or ketone is formaldehyde or methyl formed.

[0040] In one or more embodiments, in lieu of resorcinol, aralkyl-substituted resorcinolic compounds may be employed. In one or more embodiments, the aralkyl-substituted resorcinolic resin includes one or more resorcinolic units defined by the Formula (I)

where Rl is a hydrogen atom or an aralkyl group, at least one

is an alkylene bridge, and the other of R^ and

is an alkylene bridge or a hydrogen atom. The structure employed in formula (I) is intended to represent the fact that the methylene bridge(s) can be bonded to the 2, 4, or 6 position on the aromatic ring. Also, the substituent Rl, especially where R * is an aralkyl group, may be located at the 2, 4, or 6 position. The skilled person will appreciate that any carbon atom within the aromatic ring that is not bonded to a hydroxyl group, Rl, R^, or R^ will include a hydrogen atom. In one or more embodiments, the resorcinolic compounds may be defined by the Formula (II)

where Rl is a hydrogen atom or an aralkyl group.

[0041] In one or more embodiments, the aralkyl group is the residue of reacting an aralkyldienyl compound with resorcinol. In particular embodiments, the aralkyldienyl compounds include styrene, alpha-methyl styrene, beta-methyl styrene, and p-methyl styrene. As the skilled person will appreciate, where styrene is reacted with resorcinol, a resorcinolic compound defined by Formula (III) may result:

where the aralkyl-substituent (i.e. -C(CH3)(H)(CgH5)) may be referred to as a styryl substituent or styryl group. The skilled person appreciates that the styryl substituent or group is the residue of styrene following reaction with resorcinol. Accordingly, the resorcinolic compound of Formula (III) may be referred to as 4-styryl resorcinol or more generally as styryl resorcinol. In a similar fashion, where the aralkyl substituent instead derives from alpha-methyl styrene, beta- methyl styrene, or p-methyl styrene, the substituent may instead be referred to generically as a methyl styryl substituent or group, and the compound may be referred to as methyl styryl resorcinol. The skilled person appreciates that the styryl substituent (or the methyl styryl substituents) can also be bonded to the other locations on the resorcinol ring, such as the 2 or 6 position.

[0042] The condensation reaction of the resorcinol with the aldehyde or ketone may be carried out in the absence of a catalyst or in the presence of a catalyst. Useful catalysts include conventional acid catalysts. Examples of suitable acid catalysts include inorganic acids such as phosphoric acid, hydrochloric acid, and sulfuric acid. Further examples of suitable acid catalysts include heteropoly acids such as phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, and silicomolybdic acid. It will be appreciated, however, that certain catalysts may have a different effect on the resultant RF resins. Thus, in some embodiments, improvements to the RF resin, such as better adhesion, can be found by combining a phosphoric acid as the catalyst with a styrenated resorcinolic compound and methyl isobutyl ketone as the organic solvent prior to reacting with formaldehyde. In other embodiments, improvements to the RF resin, such as a lower softening point, can be found by combining sulfuric acid as a catalyst with an unsubstituted resorcinol and an organic solvent (i.e., MIBK) prior to reacting with formaldehyde.

[0043] According to aspects of the invention, the reaction of the resorcinol (or resorcinolic compound) with the aldehyde or ketone is carried out in the presence of an organic solvent. In one or more embodiments, the solvent is chosen based upon its ability to form a heterogeneous mixture with water, separate (relatively well) from the water layer, dissolve the resin polymer, not dissolve the unreacted unsubstituted resorcinol (i.e., free resorcinol), and not react with any other constituents in the formulation (i.e., it is inert with the respect to composition or reaction mixture). Also, the organic solvent should have a reasonably low boiling point so that distillation techniques can be used to separate the solvent from the reaction mixture. In one or more embodiments, the organic solvent is a polar solvent. Examples of suitable organic solvents include, but are not limited to, methyl isobutyl ketone (MIBK), methyl tert-butyl ether, cyclopentyl methyl ether, and ethyl acetate. In one embodiment, MIBK is preferably used.

[0044] In one or more embodiments, the reaction (formation of the resin) may be carried out in the temperature range of 30 to 100 °C, and in other embodiments from about 35 to about 60 °C. In one embodiment, the reaction temperature is less than 80°C, in another embodiment, the reaction temperature is less than 60°C, in another embodiment, the reaction temperature is less than 50°C, and in other embodiment, the reaction temperature is less than 45°C. In one or more embodiments, the reaction temperature is about 40°C.

[0045] In one or more embodiments, the reaction of the resorcinolic compound with the aldehyde or ketone takes place in the presence of threshold amounts of the organic solvent. Specifically, the amount or organic solvent present during the reaction can be described with reference to the amount of resorcinol charged to the reaction (i.e. in the initial mixture). In one or more embodiments, the initial mixture in which the reaction takes place includes greater than 25 parts by weight, in other embodiments greater than 50 parts by weight and in other embodiments greater than 75 parts by weight organic solvent per 100 parts by weight resorcinol. In these or other embodiments, the mixture (prior to aldehyde addition) in which the reaction takes place includes greater less than 450 parts by weight, in other embodiments less than 350 parts by weight, and in other embodiments less than 250 parts by weight organic solvent per 100 parts by weight resorcinol. In one or more embodiments, the mixture in which the reaction takes place includes from about 25 to about 450, in other embodiments from about 50 to about 350, and in other embodiments from about 75 to about 250 by weight organic solvent per 100 parts by weight resorcinol.

[0046] The skilled person can readily determine the appropriate level of catalyst that should be used. The amount of catalyst introduced to the mixture (i.e. acid catalyst prior to aldehyde addition) and be described with reference to the amount of resorcinol initially present. In one or more embodiments (e.g. where phosphoric acid is employed), the initial mixture in which the reaction takes place includes greater than 10 parts by weight, in other embodiments greater than 25 parts by weight, in other embodiments greater than 50 parts by weight, in other embodiments greater than 100 parts by weight, in other embodiments greater than 150 parts by weight, in other embodiments greater than 200 parts by weight, and in other embodiments greater than 250 parts by weight catalyst per 100 parts by weight resorcinol. In these or other embodiments, the mixture in which the reaction takes place includes greater less than 450 parts by weight, in other embodiments less than 350 parts by weight and in other embodiments less than 300 parts by weight catalyst per 100 parts by weight resorcinol. In one or more embodiments, the mixture in which the reaction takes place includes from about 10 to about 450, in other embodiments from about 25 to about 350, and in other embodiments from about 50 to about 300 parts by weight catalyst per 100 parts by weight resorcinol.

[0047] The skilled person can readily determine the appropriate level of water that should be used. The amount of water introduced to the mixture (i.e., prior to aldehyde addition) and be described with reference to the amount of resorcinol initially present. In one or more embodiments, the initial mixture in which the reaction takes place includes greater than 10 parts by weight, in other embodiments greater than 20 parts by weight, in other embodiments greater than 40 parts by weight, in other embodiments greater than 80 parts by weight, in other embodiments greater than 160 parts by weight, in other embodiments greater than 320 parts by weight and in other embodiments greater than 640 parts by weight catalyst per 100 parts by weight resorcinol. In these or other embodiments, the mixture in which the condensation reaction takes place includes less than 900 parts by weight, in other embodiments less than 800 parts by weight and in other embodiments less than 700 parts by weight catalyst per 100 parts by weight resorcinol. In one or more embodiments, the mixture in which the reaction takes place includes from about 10 to about 900, in other embodiments from about 20 to about 800, and in other embodiments from about 40 to about 700 parts by weight catalyst per 100 parts by weight resorcinol.

Isolation and Drying of RF Resin

[0048] Following the condensation reaction between the resorcinolic compound and the formaldehyde, which reactions produces the RF resins of the present invention, the resin material is separated from the other constituents within the reaction mixture.

[0049] Generally, the reaction proceeds in two phases (i.e. heterogeneously) where the resorcinol resin reaction product is dissolved or solvated in the organic solvent phase and the unreacted resorcinolic compound is dissolved or solvated in the water phase. During the reaction, the solvents are mixed. When the reaction is completed (or near completed), water is removed by draining. In some instances, the remaining organic layer is washed with water thereby removing the unreacted resorcinol. Multiple washings may be used. The organic solvent is then removed by appropriate techniques (e.g. distillation or thin-film evaporation) leaving a product as a hot molten resin, which is then removed from the vessel and cooled to form a solid resin. The solid resin can then be fabricated into various forms including, but not limited to, flakes, prills, pastilles, etc. for use. It will be appreciated that, because of the use of the organic solvent in the reaction of the resorcinolic compound and the aldehyde, far less water is needed to produce the reaction, and thus, far less water is then required to be removed.

Vulcanizable Compositions

[0050] As suggested above, the RF resins of the present invention are useful in vulcanizable rubber compositions. Besides the use of the RF resins of the present invention, the vulcanizable compositions may otherwise be conventional in nature. Accordingly, the rubber compositions may include a vulcanizable rubber, a curative, a filler, and the RF resins of the present invention.

[0051] With regard to the rubber compositions of the present invention, the rubber compositions may include a rubber component that may include any natural rubber, synthetic rubber or combination thereof. Examples of synthetic rubber include but are not limited to styrene butadiene copolymer, polyisoprene, polybutadiene, acrylonitrile butadiene styrene, polychloroprene, polyisobutylene, ethylene-propylene copolymer and ethylene-propylene-diene rubber.

[0052] The rubber compositions may also include one or more of the normal additives used in such compositions. Examples of such additives include carbon black, cobalt salts, stearic acid, silica, silicic acid, sulfur, peroxides, zinc oxide, fillers, antioxidants and softening oils.

[0053] Aspects of the present invention relate to the amount or loading of the solid RF resins of the present invention within the vulcanizable compositions. In one or more embodiments, the vulcanizable compositions of the present invention include greater than 0.5, in other embodiments greater than 1.0, in other embodiments greater than 1.5, and in other embodiments greater than 2.0 parts by weight solid RF resin (i.e. the solid RF resin of the present invention having high 4,4'-linkage content) per 100 parts by weight rubber. In these or other embodiments, the vulcanizable compositions of the present invention include less than 7.0, in other embodiments less than 6.0, in other embodiments less than 5.0, and in other embodiments less than 4.0 parts by weight of the solid RF resin per 100 parts by weight rubber. In one or more embodiments, the vulcanizable compositions of the present invention include from about 0.5 to about 7.0, in other embodiments from about 1.0 to about 6.0, in other embodiments from about 1.5 to about 5.0, and in other embodiments from about 2.0 to about 4.5 parts by weight of the RF resin per 100 parts by weight rubber.

[0054] The rubber composition may also include one or more of a methylene donor component. The methylene donor component is any compound that generates formaldehyde upon heating during the vulcanization. Examples of such compounds are set forth in U.S. Pat. No. 3,751,331, which is incorporated herein by reference. Preferred methylene donor compounds are hexamethylenetetramine, di-methylol melamine, tri-methylol melamine, tetra- methylol melamine, penta-methylol melamine, hexa-methylol melamine, and mixtures thereof. The methylol melamines may be completely or partially etherified or esterified such as hexamethoxymethylol melamine. The methylene donor may be present in concentrations from about 0.1 to 15 parts per one hundred parts rubber or in other embodiments from 0.1 to 10 parts per one hundred parts rubber. The ratio of methylene donor to solid RF novolac resin may be from 1 : 10 to 10:1.

[0055] As should be appreciated, the rubber component, additives, reinforcing materials and methylene donor compounds are known. In addition, the method of vulcanizing the compositions is known. The improvements of the present invention are related to solid RF novolac resins.

[0056] The rubber compositions are prepared and used in the conventional manner of preparing and using such compositions. Namely, the compositions can be prepared by solid- state mixing.

Industrial Applicability

[0057] The rubber compositions produced according to the present invention may be used for various rubber applications or rubber goods. The uncured and cured rubber compositions of this invention may be used in tire applications or used to prepare portions of a tire, such as tire treads, belt skim stock, sidewalls, bead compounds, carcasses, or other areas of a tire. Other applications include rubber products that are useful for engine mounts and bushings. Still other examples of applications in which the uncured and cured rubber compositions of this invention may be used or used to prepare include technical or mechanical rubber goods such as hoses, pneumatic belts, and conveyor belts.

EXAMPLES

[0058] In order to demonstrate the practice of the present invention, the following examples have been prepared and tested. The examples should not, however, be viewed as limiting the scope of the invention. The claims will serve to define the invention.

SRF Resin Example 1.

[0059] 150.0 g of resorcinol was charged to a flask and heated to 120 °C - 135 °C. 0.46 g of p-toluene sulfonic acid was then added and mixed for 10 minutes. 11.8 g of styrene was then charged to the flask stream-wise over a period of about 15 minutes while the temperature was maintained at 120 °C - 135 °C. After all of the styrene was charged, the temperature was increased to 150 °C - 155 °C and was maintained at 150 °C - 155 °C for 15 minutes. Styrene- substituted resorcinol (i.e., the resorcinolic compound) was thus formed. Then, 75 .0 g of water, 300.0 g of methyl isobutyl ketone, and 155.5 g of a 85% phosphoric acid aqueous solution was charged to form a mixture with the resorcinol. Subsequently, 62.6 g of a 37% formaldehyde aqueous solution was charged stream-wise to the mixture at about 40°C over a period of 60 minutes. After all of the aldehyde was charged, the reaction mixture was maintained at about 40°C for another 1 to 2 hours. Afterward, the water layer was substantially removed, and the organic layer was washed several times with water. Then, 0.5 g of 25% sodium hydroxide solution was added. Solvent was then removed by vacuum distillation to 155 °C. When a temperature of 155 °C was reached, the vacuum was released and the resin was discharged from the flask.

SRF Resin Example 2

[0060] 200.0 g of resorcinol was charged to a flask and heated to 120 °C - 135 °C. 0.61 g of p-toluene sulfonic acid was then added and mixed for 10 minutes. 31.5 g of styrene was then charged to the flask stream -wise over a period of about 30 minutes while the temperature was maintained at 120 °C - 135 °C. After all the styrene was charged, the temperature was increased to 150 °C - 155 °C and maintained for 15 minutes. A styrene- substituted resorcinol (i.e., the resorcinolic compound) was thus formed. Then, 350.0 g of water, 200.0 g of methyl isobutyl ketone, and 226.1 g of a 78% sulfuric acid aqueous solution was charged to form a mixture with the resorcinol, Subsequently, 91.6 g of 37% formaldehyde in aqueous solution was charged stream-wise to the mixture at about 40 °C over a period of 60 minutes. After all of the formaldehyde was charged, the reaction mixture was maintained at about 40°C for another 1 to 2 hours. Afterward, the water layer was substantially removed. Then, 0.6 g of 28% sodium hydroxide solution was added. Solvent was then removed by vacuum distillation to 155 °C. When a temperature of 155 °C was reached, the vacuum was released and the resin was discharged from the flask.

SRF Resin Example 3

[0061] 150.0 g of resorcinol was charged to a flask and heated to 120 °C - 135 °C. 0.46 g of p-toluene sulfonic acid was then added and mixed for 10 minutes. 23.6 g of styrene was then charged to the flask stream -wise over a period of about 30 minutes while the temperature was maintained at 120 °C - 135 °C. After all the styrene was charged, the temperature was increased to 150 °C - 155 °C and maintained for 15 minutes. A styrene-substituted resorcinol (i.e., the resorcinolic compound) was thus formed. Then, 75 .0 g of water, 300.0 g of methyl isobutyl ketone, and 155.5 g of a 85% phosphoric acid aqueous solution was charged to form a mixture with the resorcinol. Subsequently, 68.9 g of a 37% formaldehyde in aqueous solution was charged stream-wise to the mixture at about 40°C over a period of 60 minutes. After all of the aldehyde was charged, the reaction mixture was maintained at about 40°C for another 1 to 2 hours. Afterward, the water layer was substantially removed, and the organic layer was washed several times with water. Then, 0.5 g of 25% sodium hydroxide solution was added. Solvent was then removed by vacuum distillation to 155 °C. When a temperature of 155 °C was reached, the vacuum was released and the resin was discharged from the flask.

SRF Resin Example 4

[0062] 150.0 g of resorcinol was charged to a flask and heated to 120 °C - 135 °C. 0.46 g of p-toluene sulfonic acid was then added and mixed for 10 minutes. 38.0 g of styrene was then charged to the flask stream-wise over a period of about 40 minutes while the temperature was maintained at 120 °C - 135 °C. After all the styrene was charged, the temperature was increased to 150 °C - 155 °C and maintained for 15 minutes. A styrene-substituted resorcinol (i.e., the resorcinolic compound) was thus formed. Styrene- substituted resorcinol (i.e., the resorcinolic compound) was thus formed. Then, 75 .0 g of water, 300.0 g of methyl isobutyl ketone, and 155.5 g of a 85% phosphoric acid aqueous solution was charged to form a mixture with the resorcinol. Subsequently, 68.9 g of a 37% formaldehyde aqueous solution was charged stream- wise to the mixture at about 40°C over a period of 60 minutes. After all of the formaldehyde was charged, the reaction mixture was maintained at about 40°C for another 1 to 2 hours. Afterward, the water layer was substantially removed, and the organic layer was washed several times with water. Then, 0.5 g of 25% sodium hydroxide solution was added. Solvent was then removed by vacuum distillation to 155 °C. When a temperature of 155 °C was reached, the vacuum was released and the resin was discharged from the flask.

SRF Resin Example 5

[0063] 150.0 g of resorcinol was charged to a flask and heated to 120 °C - 135 °C. 0.45 g of p-toluene sulfonic acid was then added and mixed for 10 minutes. 88.5 g of styrene was then charged to the flask stream-wise over a period of about 100 minutes while the temperature was maintained at 120 °C - 135 °C. After all the styrene was charged, the temperature was increased to 150 °C - 155 °C and maintained for 15 minutes. A styrene-substituted resorcinol (i.e., the resorcinolic compound) was thus formed. Then, 262.3 g of water, 150.0 g of methyl isobutyl ketone, and 169.6 g of 97% sulfuric acid was charged to form a mixture with the resorcinol. Subsequently, 68.9 g of a 37% formaldehyde aqueous solution was charged stream-wise to the mixture at about 40°C over a period of 60 minutes. After all of the formaldehyde was charged, the reaction mixture was maintained at about 40°C for another 1 to 2 hours. Afterward, the water layer was substantially removed, and the organic layer was washed several times with water. Then, 3.0 g of 25% sodium hydroxide solution was added. Solvent was then removed by vacuum distillation to 155 °C. When a temperature of 155 °C was reached, the vacuum was released and the resin was discharged from the flask.

SRF Resin Example 6

[0064] 150.0 g of resorcinol was charged to a flask and heated to 120 °C - 135 °C. 0.46 g of p-toluene sulfonic acid was then added and mixed for 10 minutes. 88.5 g of styrene was then charged to the flask stream-wise over a period of about 90 minutes while the temperature was maintained at 120 °C - 135 °C. After all the styrene was charged, the temperature was increased to 150 °C - 155 °C and maintained for 15 minutes. A styrene-substituted resorcinol (i.e., the resorcinolic compound) was thus formed. Then, 75 .0 g of water, 300.0 g of methyl isobutyl ketone, and 155.5 g of a 85% phosphoric acid aqueous solution was charged to form a mixture with the resorcinol. Subsequently, 68.9 g of a 37% formaldehyde aqueous solution was charged stream-wise to the mixture at about 40°C over a period of 60 minutes. After all of the aldehyde was charged, the reaction mixture was maintained at about 40°C for another 1 to 2 hours. Afterward, the water layer was substantially removed, and the organic layer was washed several times with water. Then, 0.5 g of 25% sodium hydroxide solution was added. Solvent was then removed by vacuum distillation to 155 °C. When a temperature of 155 °C was reached, the vacuum was released and the resin was discharged from the flask.

RF Resin Example 7

[0065] 150.0 g of resorcinol, 800.0 g of water, 300.0 g of methyl isobutyl ketone, and 300.0 g of a 97% sulfuric acid aqueous solution was charged, followed by 76.6 g of 37% formaldehyde in aqueous solution at 40 °C over a period of 60 minutes. After all of the formaldehyde was charged, the reaction mixture was maintained at about 40°C for another 1 to 2 hours. Afterward, the water layer was substantially removed, and the organic layer was washed several times with water. Then, 1.3 g of 25% sodium hydroxide solution was added. Solvent was then removed by vacuum distillation to 155 °C. When a temperature of 155 °C was reached, the vacuum was released and the resin was discharged from the flask.

RF Resin Example 8

[0066] 150.0 g of resorcinol, 75.0 g of water, 300.0 g of methyl isobutyl ketone, and 155.5 g of an 85% phosphoric acid aqueous solution was charged, followed by 76.6 g of a 37% formaldehyde aqueous solution at 40 °C over a period of 60 minutes. After all of the formaldehyde was charged, the reaction mixture was maintained at about 40°C for another 1 to 2 hours. Afterward, the water layer was substantially removed, and the organic layer was washed several times with water. Then, 0.5 g of 25% sodium hydroxide solution was added. Solvent was then removed by vacuum distillation to 155 °C. When a temperature of 155 °C was reached, the vacuum was released and the resin was discharged from the flask. [0067] TABLE I below provides a general description of the ingredients used in the formation of the resorcinolic resin, whether it be a styrenated RF resin (SRF Resin) or a RF Resin. It will be appreciated that either phosphoric acid (H3P04) or sulfuric acid (H2S04) was used as the catalyst in these examples. The various physical properties and chemical analysis of the solid RF or SRF resin are also provided. It will be appreciated that, in evaluating the resin properties, the softening point of the resins was determined using the procedure described above, the free resorcinol was determined by liquid chromatography, the methylene bridge distribution, which is the ratio of the 4,4'4inkage content to the 2-position content of the resorcinol (2,4’- and 2,2’-linkage), was determined by 1H-NMR, and the molecular weight and oligomer distribution was determined by GPC analysis. The resultant rubber performance based upon the preparation of a vulcanized rubber as set forth below is also provided in TABLE I. It will be appreciated that T’90 was measured with the Alpha Technologies MDR Rheometer (MDR2000) at l50°C, 0.5° arc and 1.6 Elz according to ASTM D-5289. The rubber compounds were cured at 150 °C, 10 tons pressure, according to parameters obtained from the MDR2000 rheometric test data. Unaged pull out force was measured according to ASTM D-2229.

[0068] TABLE I - Composition, properties, and rubber performance of Examples 1-8

[0069] In order to provide a full analysis of the improvements provided by the uniquely prepared RF and SRF resins above, comparative examples were prepared and tested for essentially the same properties and rubber performance characteristics. Such comparative examples were prepared as follows.

Comparative Example 1. SRF Resin

[0070] 150.0 g of resorcinol was charged to a flask and heated to 120 °C - 135 °C. 0.46 g of p-toluene sulfonic acid was then added and mixed for 10 minutes. 11.8 g of styrene was then charged to the flask stream-wise over a period of about 15 minutes while the temperature was maintained at 120 °C - 135 °C. After all of the styrene was charged, the temperature was increased to 150 °C - 155 °C and was maintained at 150 °C - 155 °C for 15 minutes. 62.6 g of 37% formaldehyde solution was then charged to the reactor stream -wise over a period of 60 minutes, during which time the temperature dropped and reflux occurred. After all the formaldehyde was added, the mixture was held at reflux for 5 minutes. Then, 0.4 g of a 25% solution of sodium hydroxide was added. Water was then removed by atmospheric distillation to 145 °C. Vacuum was applied and distillation continued to 155 °C. When a temperature of 155 °C was reached, the vacuum was released and the resin was discharged from the flask.

Comparative Example 2 SRF Resin

[0071] 150.0 g of resorcinol was charged to a flask and heated to 120 °C - 135 °C. 0.45 g of p-toluene sulfonic acid was then added and mixed for 10 minutes. 38.0 g of styrene was then charged to the flask stream-wise over a period of about 40 minutes while the temperature was maintained at 120 °C - 135 °C. After all of the styrene was charged, the temperature was increased to 150 °C - 155 °C and was maintained at 150 °C - 155 °C for 15 minutes. 68.9 g of 37% formaldehyde solution was then charged to the reactor stream -wise over a period of 60 minutes, during which time the temperature dropped and reflux occurred. After all the formaldehyde was added, the mixture was held at reflux for 5 minutes. Then, 0.4 g of a 25% solution of sodium hydroxide was added. Water was then removed by atmospheric distillation to 145 °C. Vacuum was applied and distillation continued to 155 °C. When a temperature of 155 °C was reached, the vacuum was released and the resin was discharged from the flask.

Comparative Example 3 SRF Resin

[0072] 150.0 g of resorcinol was charged to a flask and heated to 120 °C - 135 °C. 0.45 g of p-toluene sulfonic acid was then added and mixed for 10 minutes. 88.5 g of styrene was then charged to the flask stream-wise over a period of about 40 minutes while the temperature was maintained at 120 °C - 135 °C. After all of the styrene was charged, the temperature was increased to 150 °C - 155 °C and was maintained at 150 °C - 155 °C for 15 minutes. 68.9 g of 37% formaldehyde solution was then charged to the reactor stream -wise over a period of 90 minutes, during which time the temperature dropped and reflux occurred. After all the formaldehyde was added, the mixture was held at reflux for 5 minutes. Then, 0.4 g of a 25% solution of sodium hydroxide was added. Water was then removed by atmospheric distillation to 145 °C. Vacuum was applied and distillation continued to 155 °C. When a temperature of 155 °C was reached, the vacuum was released and the resin was discharged from the flask.

Comparative Example 4 RF Resin

[0073] 150.0 g of resorcinol was charged to a flask and heated to 120 °C - 135 °C. 76.6 g of

37% formaldehyde solution was then charged to the reactor stream-wise over a period of 90 minutes, during which time the temperature dropped and reflux occurred. After all the formaldehyde was added, the mixture was held at reflux for 5 minutes. Water was then removed by atmospheric distillation to 145 °C. Vacuum was applied and distillation continued to 155 °C. When a temperature of 155 °C was reached, the vacuum was released and the resin was discharged from the flask.

Comparative Example 5 RF Resin [0074] 150.0 g of resorcinol, 155.5 g of 85% phosphoric acid and 76.6g of 37% formaldehyde solution were charged to a flask and heated to 98 °C - 102 °C. The mixture was held at reflux for 6 hours. Afterward, 300. Og of methyl isobutyl ketone was added and the water layer was removed and the organic layer was washed several times with water. Then, 2.0g of 25% sodium hydroxide solution was added. Solvent was removed by vacuum distillation to l55°C. When a temperature of 155 °C was reached, the vacuum was released and the resin was discharged from the flask.

[0075] TABLE II below provides a general description of the ingredients used in the formation of the comparative examples, whether they be a styrenated RF resin (SRF Resin) or a RF Resin. It will be appreciated that the standard catalyst, namely, /^-toluene sulfonic acid, was used as the catalyst all of these comparative examples except Comparative Example 5, which uses phosphoric acid. The various physical properties and chemical analysis of the solid RF or SRF resin comparative examples are also provided. Finally, the rubber performance based upon the preparation of a vulcanized rubber as set forth below is also provided in TABLE II.

[0076] TABLE II - Composition, properties and rubber performance of Comp. Exs. 1-5

Rubber Compound Examples.

[0077] Rubber compounds containing the resorcinolic resins described in the examples and in TABLE I as well as those resorcinolic resins described in the comparative examples and in TABLE II were prepared according to the composition shown in TABLE III.

TABLE III: Formulation (parts by weight).

[0078] In comparison between the resorcinolic resins of the present invention and those of the comparative examples, it will be appreciated that the resorcinolic resins of the present invention have significantly less free resorcinol remaining compared to the comparative examples. Likewise, the water (moisture) content is significantly lower as compared to the comparative examples.

[0079] Furthermore, the resultant vulcanizate of the vulcanizable rubber compositions made with the resorcinolic resins of the present invention have significantly better adhesion than the comparative examples. By“better adhesion” it is meant that the unaged pull out force, in newtons, is significantly higher for each of the SRF and RF resins of the present invention as compared to the conventionally prepared comparative examples. [0080] Also, it will be appreciated that those styrenated RF resins of the present invention (Examples 1-6) have a lower softening point that their comparative conventionally prepared counterpart compositions.

[0081] Still further, the resorcinolic resins of the present invention have significantly less pentamer and higher oligomer content that do the comparative examples. In the present invention, the pentamer and higher oligomer content is less than 55%, while in the comparative examples, the content is greater than 55% in each example.

[0082] Various modifications and alterations that do not depart from the scope and spirit of this invention will become apparent to those skilled in the art. This invention is not to be duly limited to the illustrative embodiments set forth herein.

Claims

CLAIMS What is claimed is:

1. A process of making a solid resorcinolic resin comprising:

forming a mixture including a resorcinolic compound, water, an organic solvent, and, optionally, an acid catalyst;

adding an aldehyde to the mixture to thereby react the aldehyde with the resorcinolic compound and form a reaction mixture including a resorcinolic resin, unreacted resorcinolic compound, the organic solvent, and water;

substantially removing the water from the reaction mixture to thereby produce an organic composition containing the resorcinolic resin, the organic solvent, and optionally unreacted resorcinolic compound; and

removing the organic solvent from the organic composition to provide the solid resorcinolic resin.

2. The process of claim 1, where the unreacted resorcinolic compound includes free resorcinol, and where said step of substantially removing water substantially lowers the amount of the free resorcinol remaining in the organic composition produced from the reaction mixture.

3. The process of any of the preceding claims, where the reaction mixture is maintained at a temperature of less than 80 °C, preferably less than 60 °C, preferably less than 50 °C, and more preferably, less than 45 °C prior to said step of substantially removing water.

4. The process of any of the preceding claims, where the resorcinolic compound includes an aralkyl-substituted resorcinol, where said unreacted resorcinolic compound includes aralkyl-substituted resorcinol, and where the solid resorcinolic resin includes aralkyl- substituted resorcinol.

5. The process of any of the preceding claims, further comprising the step of adding an aldehyde to the reaction mixture.

6. The process of any of the preceding claims, further comprising the step of maintaining the reaction mixture under reaction conditions prior to said step of substantially removing the water, where said step of maintaining extends for greater than 15 minutes, preferably greater than 30 minutes, and more preferably, greater than 60 minutes, and where the reaction mixture is maintained at a temperature of less than 80 °C, preferably less than 60 °C, preferably less than 50 °C, and more preferably, less than 45 °C prior to said step of substantially removing water.

7. The process of any of the preceding claims, wherein the organic solvent is selected from the group consisting of methyl isobutyl ketone (MIBK), methyl tert-butyl ether, cyclopentyl methyl ether, and ethyl acetate.

8. The process of any of the preceding claims, wherein the acid catalyst is selected from the group consisting of inorganic acids, heteropoly acids, and combinations thereof.

9. The process of any of the preceding claims, wherein the acid catalyst is selected from the group consisting of phosphoric acid, sulfuric acid, hydrochloric acid, phosphotungstic acid, phosphomolybdic acid, and silicomolybdic acid.

10. The process of any of the preceding claims, wherein the aldehyde is formaldehyde.

11. The process of any of the preceding claims, where said step of adding aldehyde includes adding an aqueous solution including an aldehyde.

12. The process of any of the preceding claims, where the mixture includes greater than 25 parts by weight organic solvent and greater than 25 parts by weight water per 100 parts by weight resorcinolic compound.

13. The process of any of the preceding claims, where said step of substantially removing water removes greater than 75 wt %, preferably 85 wt %, preferably 90 wt %, preferably 95 wt %, and preferably 97 wt % of any free resorcinol within the reaction mixture.

14. The process of any of the preceding claims, further including the step of washing the solvent-containing composition to remove unreacted resorcinolic compound.

15. The process of any of the preceding claims, where the molar ratio of aldehyde to resorcinolic compound is less than 1 : 1.

16. The process of any of the preceding claims, where the solid resorcinolic resin includes less than 2 wt %, preferably less than 1 wt %, preferably less than 0.5 wt %, preferably less than 0.25 wt % free resorcinol.

17. The process of any of the preceding claims, wherein the solid resorcinolic resin comprises greater than 60 mol%, and preferably, greater than 65 mol% 4,4’-linkage content.

18. The process of any of the preceding claims, wherein the solid resorcinolic resin has a pentamer or higher oligomer content of less than 55% according to GPC using a polystyrene standard.

19. The process of any of the preceding claims, wherein the organic solvent is methyl isobutyl ketone, the catalyst is phosphoric acid, and the aldehyde is formaldehyde, and wherein the solid resorcinolic resin has a lower softening point as compared to conventional solid resorcinolic resins prepared with a resorcinolic compound reacted with formaldehyde in the presence of water and a p-toluene sulfonic acid catalyst without any organic solvent present.

20. A solid resorcinolic resin formed by the reaction of a resorcinolic compound with formaldehyde in the presence of water, methyl isobutyl ketone and, optionally, a catalyst selected from phosphoric acid or sulfuric acid, the solid resorcinolic resin comprising: a resin including units defined by the formula (I)

where Rl is a hydrogen atom or an aralkyl group, at least one of R2 and R3 is an alkylene bridge, and the other of R2 and R3 is an alkylene bridge or a hydrogen atom; and includes less than 2 wt.% water and has greater than 60 mol % 4,4'-linkage content.

21. The solid resorcinolic resin of claim 20, having a pentamer or higher oligomer content of less than 55%.

22. The solid resorcinolic resin of claim 20 or 21, having less than 2 wt.% free resorcinol.

23. The solid resorcinolic resin of claims 20-22, having a lower softening point as compared to conventional solid resorcinolic resins prepared with a resorcinolic compound reacted with formaldehyde in the presence of water and a p-toluene sulfonic acid catalyst without any organic solvent present.

24. The solid resorcinolic resin of claims 20-23, having less than 0.5 wt.% water.

25. The solid resorcinolic resin of claims 20-24, having a Mw of greater than 600 and less than 1500 g/mol.

26. A vulcanizable rubber composition comprising:

a. A vulcanizable rubber;

b. A curative; and

c. Solid resorcinolic resin prepared by the process of claim 1 and/or according to claim 21, and including less than 2 wt.% water, and greater than 60 mol % 4,4'- linkage content.

27. The vulcanizable rubber composition of claim 26, wherein the solid resorcinolic resin includes less than 1 wt.%., preferably less than 0.5 wt.%, free resorcinol.

28. The vulcanizable rubber composition of claim 26 or 27, wherein the solid resorcinolic resin includes less than 1 wt.%, and preferably less than 0.5 wt.%, water.

29. The vulcanizable rubber composition of claims 26-28, wherein the resorcinolic resin has a softening point lower than conventionally prepared resorcinolic resins, but the vulcanizable composition, when vulcanized, has a cure time (T’90) essentially the same as the vulcanized rubber composition prepared with conventional resorcinolic resins.

30. The vulcanizable rubber composition of claims 26-29, where the vulcanizable composition, when vulcanized, exhibits better adhesion as determined by unaged pull out force, than vulcanized compositions containing conventional resorcinolic resins.

31. A vulcanized rubber prepared from the vulcanizable composition of claim 26.