Phloroglucinol resin, preparation method and use in rubber composition

Abstract

A solid phloroglucinol resin comprises reacting a phloroglucinol compound with a ketone in the presence of an acid catalyst. The solid phloroglucinol resin formed comprises a plurality of phloroglucinol units defined by formula (I), wherein at least one of R1, R2 and R3 is combined with a second phloroglucinol unit to form a disubstituted methylene bridge, wherein a second of R1, R2 and R3 is a hydrogen atom or is combined with a third phloroglucinol unit to form another disubstituted methylene bridge, and wherein a third of R1, R2 and R3 is a hydrogen atom.

Description

Technical Field

[0001] The present invention relates to a solid phloroglucinol resin and a method for preparing the same. The solid phloroglucinol resin can be used in a vulcanizable rubber composition. Background Art

[0002] Resorcinol-formaldehyde resins, also known as RF resins or resorcinol-based resins, which are formed as the reaction product of resorcinol and formaldehyde, have been widely used in various applications including rubber compounding. In rubber mix formulations, solid RF resins have long been used to enhance rubber properties, such as adhesion properties between rubber and reinforcement materials and dynamic properties in articles such as tires, belts, and hose products.

[0003] Resorcinol resins typically have 10-20% unreacted or free resorcinol. The amount of free resorcinol can be a critical factor when balancing important properties. However, the presence of free resorcinol can create problems. For example, free resorcinol can volatilize during rubber mixing, which is often referred to as fuming, thereby causing additional problems in the rubber mixing process. In addition, the presence of free resorcinol contributes to the hygroscopicity of resorcinol-based resins, which in turn can cause storage and handling problems.

[0004] For many years, formaldehyde has been used in the production of resorcinol-formaldehyde resins. Given its widespread use, toxicity, and volatility, formaldehyde presents potential health and environmental concerns. In 2011, the US National Toxicology Program described formaldehyde as a known human carcinogen.

[0005] Therefore, there is a need to produce environmentally friendly adhesives that do not use resorcinol and formaldehyde (or other aldehydes). Unfortunately, to date, all known prior art adhesive resins that do not contain resorcinol and formaldehyde have been found to generally have low reactivity, which leads to unsatisfactory rubber properties and / or processing problems. For example, the softening point of the resin can be adversely affected, resulting in difficulties in use and processing. That is, too high a softening point can lead to difficulties during mixing with the rubber compound, while too low a softening point can lead to handling problems. Therefore, there is a need to balance the competing factors of reactivity and softening point.

[0006] The use of phloroglucinol in aqueous adhesive compositions is well known. For example, in U.S. Patent Application Publication No. US 2014 / 0235125, it is noted that the aqueous adhesive composition comprises a phenol / aldehyde resin and an unsaturated elastomer latex. The phenol / aldehyde resin is based on at least one of the following: an aromatic polyaldehyde with at least two aldehyde functional groups and including at least one aromatic nucleus; and phloroglucinol.

[0007] In U.S. Patent Application Publication No. US 2019 / 0119535, an aqueous adhesive composition comprises a thermosetting resin and an unsaturated elastomer latex. The thermosetting resin may include an aromatic compound with at least two functional groups, one of which is a hydroxymethyl functional group and the other is an aldehyde functional group or a hydroxymethyl functional group. In general, although phloroglucinol is disclosed in both references, it is noted that both compositions are aqueous (not solid) and preferably contain aldehydes (not ketones). Summary of the invention

[0008] At least one aspect of the present invention provides a solid phloroglucinol resin comprising a reaction product of a phloroglucinol compound (preferably phloroglucinol) and a ketone. In various embodiments, the ketone may be selected from the group consisting of: acetone, methyl ethyl ketone, diethyl ketone, ethyl butyl ketone, diisobutyl ketone, methyl isopropyl ketone, diisopropyl ketone and methyl isobutyl ketone. In other embodiments, the ketone may be selected from the group consisting of: acetone, methyl ethyl ketone and methyl isobutyl ketone. In at least one embodiment, the ketone is acetone. In another embodiment, the ketone is methyl ethyl ketone. In yet another embodiment, the ketone is methyl isobutyl ketone.

[0009] To produce a solid phloroglucinol resin, the phloroglucinol compound is reacted with a ketone in the presence of an acid catalyst. In at least one embodiment, the acid catalyst is selected from a mineral acid, an acidic cation exchange resin, and a combination thereof. In at least one embodiment, the mineral acid is thioglycolic acid (thioglycolic acid). In at least another embodiment, the acidic cation exchange resin comprises sulfuric acid or hydrochloric acid.

[0010] Other aspects of the present invention provide a vulcanizable rubber composition comprising a vulcanizable rubber; a curing agent; and a solid phloroglucinol resin comprising a reaction product of a phloroglucinol compound and a ketone. In addition and advantageously, it will be appreciated that the vulcanizable rubber composition of the present invention exhibits favorable rubber properties (such as adhesion, hardness, and dynamic properties) compared to conventional products without affecting the curing time during vulcanization.

[0011] In general, it will be appreciated that the present invention provides a solid phloroglucinol resin comprising a plurality of phloroglucinol units defined by formula (I):

[0012]

[0013] wherein at least one of R1, R2 and R3 is combined with a second phloroglucinol unit to form a disubstituted methylene bridge, wherein a second one of R1, R2 and R3 is a hydrogen atom or is combined with a third phloroglucinol unit to form another disubstituted methylene bridge, and wherein a third one of R1, R2 and R3 is a hydrogen atom.

[0014] More specifically, the present invention also provides the above solid phloroglucinol resin further defined by formula (II):

[0015]

[0016] wherein n is an integer from 1 to 20, wherein R1 in the first phloroglucinol unit on the left has been substituted at the 2-position with a disubstituted methylene bridge, and R3 in the second phloroglucinol unit on the right has been substituted at the 6-position with the same disubstituted methylene bridge; wherein R3 on the first phloroglucinol unit on the left and R1 on the second phloroglucinol unit on the right form a single disubstituted methylene bridge or may be a hydrogen atom, and R2 is a hydrogen atom, and wherein R4 and R5 may be the same or different and are alkyl groups.

[0017] In some embodiments based on the above resins, the solid phloroglucinol resin may have R4 and R5 both being methyl, wherein the disubstituted methylene bridge formed is an isopropylidene bridge. In other embodiments based on the above resins, R4 may be ethyl and R5 may be methyl, wherein the disubstituted methylene bridge formed is a 2,2 disubstituted butane bridge. In other embodiments based on the above resins, R4 may be isopropyl and R5 may be methyl, wherein the disubstituted methylene bridge formed is a 2,2 disubstituted 4-methylpentane bridge.

[0018] Another aspect of the present invention provides a solid phloroglucinol resin, which comprises the reaction product of phloroglucinol and a ketone in the presence of an acid catalyst. For this resin, the ketone can be selected from the group consisting of: acetone, methyl ethyl ketone (MEK), diethyl ketone, ethyl butyl ketone, diisobutyl ketone, methyl isopropyl ketone, diisopropyl ketone and methyl isobutyl ketone (MIBK). In some embodiments, the ketone can be selected from the group consisting of: acetone, methyl ethyl ketone and methyl isobutyl ketone. In some embodiments, the acid catalyst is selected from the group consisting of: an inorganic acid and an acidic cation exchange resin.

[0019] In one or more embodiments based on the above resin, the molar ratio of ketone to phloroglucinol may be greater than 1:1 and less than 20:1. In one or more embodiments based on the above resin, the resin may contain less than 40wt% of unreacted phloroglucinol. In one or more embodiments based on the above resin, the resin may have a weight average molecular weight (Mw) greater than 400 and less than 700g / mol. In one or more embodiments based on the above resin, the resin may have a softening point greater than 80°C. In one or more embodiments based on the above resin, the resin may contain less than 1.5wt% of water. In one or more embodiments based on the above resin, the resin may have a content of pentamers or higher oligomers less than 55% according to GPC using polystyrene standards.

[0020] Another aspect of the present invention provides a vulcanizable rubber composition, which comprises a vulcanizable rubber, a curing agent and the solid phloroglucinol resin as described above. In another aspect, a vulcanized rubber prepared from the vulcanizable composition can be provided. DETAILED DESCRIPTION

[0021] The present invention is based at least in part on the discovery that solid phloroglucinol resins can replace solid RF resins when compounded into vulcanizable rubber compositions. Such solid phloroglucinol resins do not use resorcinol or aldehydes (such as formaldehyde). Instead, the solid phloroglucinol resins include a plurality of phloroglucinol units generally defined by formula (I):

[0022]

[0023] wherein at least one of R1, R2 and R3 is bonded to a second phloroglucinol unit to form a disubstituted methylene bridge, wherein the second of R1, R2 and R3 is a hydrogen atom or is bonded to a third phloroglucinol unit to form another disubstituted methylene bridge, and wherein the third of R1, R2 and R3 is a hydrogen atom. The structure employed in formula (I) is intended to represent the fact that the disubstituted methylene bridge of R1, R2 or R3 can be bonded to the 2, 4 or 6 position on the aromatic ring. In addition, the hydrogen atom of R1, R2 or R3 is also located at the 2, 4 or 6 position. The skilled person will understand that any carbon atom in the aromatic ring that is not bonded to the hydroxyl group can be bonded to R1, R2 or R3 and will include a hydrogen atom or be part of a disubstituted methylene bridge.

[0024] Typically, the disubstituted methylene bridge includes a methylene bridge with at least two C1 to C10 alkyl groups extending from the methylene bridge. In another embodiment, the methylene bridge includes at least two C1 to C5 alkyl groups extending therefrom. In yet another embodiment, the methylene bridge includes at least two C1 to C4 alkyl groups extending therefrom. In yet another embodiment, the methylene bridge includes at least two C1 to C3 alkyl groups extending therefrom. In another embodiment, the methylene bridge includes at least two C1 to C2 alkyl groups extending therefrom.

[0025] More specifically, the phloroglucinol resin of the present invention can be described as shown in formula (II):

[0026]

[0027] Wherein, n is an integer from 1 to 20, wherein R1 in the phloroglucinol unit on the left has been substituted with a disubstituted methylene bridge at position 2 as shown, and R3 in the phloroglucinol unit on the right has been substituted at position 6; R3 on the left and R1 on the right may also be the same disubstituted methylene bridge as shown herein or may be a hydrogen atom, while R2 may be a hydrogen atom in the embodiment shown here. R4 and R5 may be the same or different and are alkyl groups. In one embodiment, R4 and R5 may both be methyl groups, wherein the disubstituted methylene bridge formed is an isopropylidene bridge. In another embodiment, R4 may be an ethyl group and R5 may be a methyl group, wherein the disubstituted methylene bridge formed is a 2,2 disubstituted butane bridge. In yet another embodiment, R4 may be an isopropyl group and R5 may be a methyl group, wherein the disubstituted methylene bridge formed is a 2,2 disubstituted 4-methylpentane bridge. In some embodiments, n is an integer from 1 to 8, and in other embodiments, n is an integer from 1 to 5.

[0028] As described above, various aspects of the present invention benefit from the solid nature of the phloroglucinol resin. Thus, the phloroglucinol resin of the present invention may be characterized in that there is no water or a limited amount of water in the phloroglucinol resin. Relative to the total weight of the solid resin, the solid phloroglucinol resin of the present invention contains less than 3wt% in one or more embodiments, less than 2wt% in other embodiments, less than 1wt% in other embodiments, less than 0.5wt% in other embodiments, less than 0.25wt% in other embodiments, and less than 0.10wt% of water in other embodiments. In one or more embodiments, the phloroglucinol resin of the present invention is substantially free of water, which refers to an amount of water or less that does not have a significant effect on the resin or its use. In a specific embodiment, the phloroglucinol resin of the present invention is free of water. As will be appreciated by those skilled in the art, the amount of water in the resin can be determined by a variety of methods, including but not limited to the Karl Fischer titration method. In a specific embodiment, the amount of water is determined using a revised version of ASTM E 203, wherein the method is revised by replacing the injection septum with a stopper and adding the crushed resin through this port.

[0029] The solid phloroglucinol resin of the present invention is characterized by low molecular weight. As will be appreciated by those skilled in the art, the molecular weight of the phloroglucinol resin can be determined using several methods, 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 the solid phloroglucinol resin include gel permeation chromatography or gas phase osmotic pressure determination using polystyrene standards (GPC).

[0030] In one or more embodiments, the solid phloroglucinol resin composition of the present invention can be characterized by a weight average molecular weight (Mw) determined by GPC using a polystyrene standard. The Mw of the resin is greater than 270 g / mol in one or more embodiments, greater than 290 g / mol in other embodiments, greater than 310 g / mol in other embodiments, greater than 350 g / mol in other embodiments, and greater than 400 g / mol in other embodiments. The Mw of the resin is less than 900 g / mol in these or other embodiments, less than 800 g / mol in other embodiments, and less than 700 g / mol in other embodiments. The solid phloroglucinol resin of the present invention can be characterized by Mw being about 270 to about 900 g / mol in these or other embodiments, about 310 to about 900 g / mol in other embodiments, about 350 to about 800 g / mol in other embodiments, and about 400 to about 700 g / mol in other embodiments.

[0031] The solid phloroglucinol resin compositions of the present invention may be characterized by a softening point of greater than 90° C. in one or more embodiments, greater than 100° C. in other embodiments, greater than 110° C. in other embodiments, greater than 120° C. in other embodiments, greater than 130° C. in other embodiments, greater than 140° C. in other embodiments, greater than 160° C. in other embodiments, and greater than 180° C. in other embodiments. The solid phloroglucinol resins of the present invention may be characterized by a softening point of from about 80° C. to about 180° C. in these or other embodiments, from about 95° C. to about 140° C. in other embodiments, and from about 100° C. to about 130° C. in other embodiments. The softening point of the resin may be determined according to the following method with reference to the latest edition of ASTM E 28 and ASTM D 6090, the entire contents of which are incorporated herein by reference. This method may 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 a cartridge assembly, a timer, a ceramic evaporating dish (approximately 3" in diameter), and a hot plate. The method may employ a pitch-type cup drilled to a 0.257" opening (F drill) and a 440 stainless steel ball (0.2500" in diameter and must pass through the cup). The apparatus may be constructed in accordance with ASTM D 6090 is calibrated. A resin sample (about 15 grams) can be melted in a porcelain or aluminum evaporating dish on a hot plate surface at 600-650°F for about 4 minutes. After melting, the sample can be poured into a cup that has been preheated to at least the temperature of the molten resin. The amount of resin sample poured into the cup should be such that after curing, excess resin sample can be removed with a heated scraper or putty knife. The sample can then be cooled to room temperature in a desiccator, and then the cylinder can be assembled so that the ball rests on top of the resin. The assembled cylinder is then placed in a furnace, which can be preset to 85°C or 10-15°C below the expected softening point. The heating rate can be set to 1°C / min. The cylinder can then be turned until it is locked in place. After 30 seconds, the operation of the softening point device can be started, thereby achieving a complete softening point measurement.

[0032] Depending on the ketone used with the phloroglucinol compound, the bridge structure developed is very similar to the methylene bridge structure shown in known RF resins. More specifically, when a ketone is combined with a phloroglucinol compound (such as phloroglucinol), a solid phloroglucinol resin having a disubstituted methylene bridge structure and a relatively low molecular weight is produced. Importantly, this new phloroglucinol resin does not use resorcinol and formaldehyde.

[0033] More specifically, in one or more embodiments, the phloroglucinol resin of the present invention is generally prepared by reacting a phloroglucinol compound with a ketone in the presence of an acid catalyst. That is, the phloroglucinol resin comprises a reaction product of phloroglucinol and a ketone in the presence of an acid catalyst. As will be appreciated by those skilled in the art, and as described above, the phloroglucinol compound includes, but is not limited to, phloroglucinol (which is also known as trihydric phenol or 1,3,5-dihydroxybenzene) or free phloroglucinol. The chemical formula of phloroglucinol is shown in the following formula (III):

[0034]

[0035] The molar ratio of ketone to phloroglucinol may vary from 1:1 to 20:1. In some other embodiments, the molar ratio may vary from greater than 1:1 to less than 20:1. In other embodiments, the molar ratio may vary from 1.5:1 to 16:1, and in other embodiments, the molar ratio may vary from greater than 1.5:1 to less than 15:1. In other embodiments, the molar ratio may vary from 2:1 to 16:1, and in other embodiments, the molar ratio may vary from greater than 2:1 to less than 15:1. In other embodiments, the molar ratio of ketone to phloroglucinol may vary from about 1.5:1 to about 10:1, in other embodiments from about 1.5:1 to about 8:1, and in other embodiments from about 2:1 to about 6:1.

[0036] In one or more embodiments, the ketone can be selected from the group consisting of acetone, methyl ethyl ketone, diethyl ketone, ethyl butyl ketone, diisobutyl ketone, methyl isopropyl ketone, diisopropyl ketone and methyl isobutyl ketone. In specific embodiments, the ketone is acetone. In other embodiments, the ketone is methyl ethyl ketone, and in other embodiments, the ketone is methyl isobutyl ketone.

[0037] The condensation reaction of phloroglucinol with ketone can be carried out in the presence of a catalyst. Useful catalysts include conventional acid catalysts. Examples of suitable acid catalysts include mineral acids (such as phosphoric acid, hydrochloric acid and sulfuric acid) and acidic ion exchange resins (such as acidic cation exchange resins). Other catalysts can also be used. Such catalysts include inorganic acid catalysts (e.g., thioglycolic acid).

[0038] According to aspects of the present invention, the reaction of phloroglucinol (or phloroglucinol compound) and ketone is carried out in the presence of an organic solvent. The example of a suitable organic solvent includes a polar solvent and a non-polar solvent. In one or more embodiments, the solvent can be selected from acetone, methyl isobutyl ketone (MIBK), methyl tert-butyl ether, cyclopentyl methyl ether, ethyl acetate, methanol, ethanol, isopropanol, n-propanol, acetonitrile, dimethyl sulfoxide, dimethylformamide and tetrahydrofuran, chlorobenzene, dichlorobenzene, pentane, hexane, toluene and dimethylbenzene. In one embodiment, acetone and toluene are preferably used.

[0039] The reaction (resin formation) may be carried out in one or more embodiments at a temperature range of 10° C. to 150° C. and in other embodiments at about 25° C. to about 130° C. In one embodiment, the reaction temperature is greater than 30° C., in another embodiment, the reaction temperature is greater than 40° C., in another embodiment, the reaction temperature is greater than 50° C., and in other embodiments, the reaction temperature is greater than 60° C.

[0040] In one or more embodiments, the reaction of the phloroglucinol compound with an aldehyde or ketone is carried out in the presence of a threshold amount of an organic solvent. Specifically, the amount of organic solvent present during the reaction can be described with reference to the amount of phloroglucinol added to the reaction (i.e., in the initial mixture). The initial mixture in which the reaction occurs includes more than 30 parts by weight in one or more embodiments, more than 50 parts by weight in other embodiments, and more than 70 parts by weight of organic solvent per 100 parts by weight of phloroglucinol in other embodiments. The mixture in which the reaction occurs (before the addition of the aldehyde) includes less than 500 parts by weight in these or other embodiments, less than 400 parts by weight in other embodiments, and less than 300 parts by weight of organic solvent per 100 parts by weight of resorcinol in other embodiments. The mixture in which the reaction occurs includes about 30 to about 500 parts by weight in one or more embodiments, about 50 to about 400 parts by weight in other embodiments, and about 70 to about 300 parts by weight of organic solvent per 100 parts by weight of resorcinol in other embodiments.

[0041] Those skilled in the art can easily determine the appropriate level of the acid catalyst to be used. The amount of the acid catalyst is introduced into the mixture and described with reference to the amount of the phloroglucinol initially present. The initial mixture in which the reaction occurs includes an inorganic catalyst per 100 weight parts of phloroglucinol greater than 0.1 weight part in one or more embodiments, greater than 0.2 weight part in other embodiments, greater than 0.5 weight part in other embodiments, greater than 1 weight part in other embodiments, greater than 2 weight parts in other embodiments, and greater than 5 weight parts in other embodiments. The mixture in which the reaction occurs includes an inorganic catalyst per 100 weight parts of phloroglucinol less than 50 weight parts in these or other embodiments, less than 40 weight parts in other embodiments, and less than 30 weight parts in other embodiments. The mixture in which the reaction occurs includes an inorganic catalyst per 100 weight parts of phloroglucinol of about 0.1 to about 50 weight parts in one or more embodiments, about 1 to about 40 weight parts in other embodiments, and about 5 to about 30 weight parts in other embodiments.

[0042] The initial mixture in which the reaction occurs includes greater than 10 parts by weight, greater than 25 parts by weight, and greater than 50 parts by weight of an acidic cation exchange catalyst per 100 parts by weight of phloroglucinol in one or more embodiments. The mixture in which the reaction occurs includes less than 500 parts by weight, less than 400 parts by weight, and less than 200 parts by weight of an inorganic catalyst per 100 parts by weight of phloroglucinol in these or other embodiments. The mixture in which the reaction occurs includes about 10 to about 500 parts by weight, about 25 to about 400 parts by weight, and about 50 to about 200 parts by weight of an acidic cation exchange catalyst per 100 parts by weight of phloroglucinol in one or more embodiments, about 50 to about 200 parts by weight, and less than 50 parts by weight of an inorganic catalyst per 100 parts by weight of phloroglucinol in other embodiments.

[0043] Those skilled in the art can easily determine the appropriate level of any mercaptan or sulfide that should be used as a co-catalyst with the acid catalyst in the reaction. The co-catalyst will enhance the reaction rate by using the acid catalyst and the phloroglucinol compound together. In one or more embodiments, the co-catalyst can be selected from the group consisting of sodium sulfate, sodium thiosulfate, sodium bisulfite, mercaptoethanol, sodium dithionite, thioglycolic acid, sodium sulfide and ethanethiol. In a specific embodiment, the co-catalyst is thioglycolic acid.

[0044] The amount of the cocatalyst is introduced into the mixture and described with reference to the amount of phloroglucinol initially present. The initial mixture in which the reaction occurs includes greater than 0.01 parts by weight in one or more embodiments, greater than 0.5 parts by weight in other embodiments, and greater than 1 part by weight of an inorganic catalyst per 100 parts by weight of phloroglucinol. The mixture in which the reaction occurs includes less than 30 parts by weight in these or other embodiments, less than 20 parts by weight in other embodiments, and less than 10 parts by weight of an inorganic catalyst per 100 parts by weight of phloroglucinol. The mixture in which the reaction occurs includes about 0.01 to about 30 parts by weight in one or more embodiments, about 0.5 to about 20 parts by weight in other embodiments, and about 1 to about 10 parts by weight of an inorganic catalyst per 100 parts by weight of phloroglucinol in other embodiments.

[0045] Turning to the production of a specific phloroglucinol resin, it will be appreciated that when acetone is combined with a phloroglucinol compound such as phloroglucinol, a phloroglucinol resin having an isopropylidene bridge structure and a relatively low molecular weight is produced. The reaction is more specifically shown in Scheme I below.

[0046]

[0047] It will be understood that each isopropylidene bridge structure is a disubstituted methylene bridge having a methyl group as a substituent group.

[0048] Similarly, when methyl ethyl ketone is used and combined with a phloroglucinol compound such as phloroglucinol, a phloroglucinol resin having a 2,2-disubstituted butane bridge structure is produced. The reaction is shown more specifically in Scheme II below.

[0049]

[0050] It is understood that each 2,2-disubstituted butane bridge structure is a disubstituted methylene bridge having one ethyl and one methyl group extending from the methylene bridge as substituent groups.

[0051] Furthermore, when methyl isobutyl ketone is used and combined with a phloroglucinol compound such as phloroglucinol, a phloroglucinol resin having a 2,2-isopropyl, 4-methylpentane bridge structure is produced. The reaction is more specifically shown in Scheme III below.

[0052]

[0053] It is understood that each 2,2-disubstituted 4-methylpentane bridge structure is a disubstituted methylene bridge having one isopropyl and one methyl group extending from the methylene bridge as substituent groups.

[0054] After removal of the solvent, the resulting product is a solid phloroglucinol resin. Importantly, these solid phloroglucinol resins, when compounded into vulcanizable rubber compositions, produce unexpected results including improvements in the physical properties of the cured rubber (e.g., Shore A hardness) and the dynamic properties of the cured rubber (e.g., higher G'), and have been found to have adequate processing characteristics (e.g., adequate cure times) that have not previously been found in alternative resins that do not contain resorcinol.

[0055] As mentioned above, phloroglucinol resin of the present invention can be used for vulcanizable rubber composition.Except using phloroglucinol resin of the present invention, vulcanizable composition can be conventional in nature.Therefore, rubber composition can comprise vulcanizable rubber of the present invention, curing agent, filler and phloroglucinol resin.

[0056] Regarding the rubber composition of the present invention, the rubber composition can include a rubber component, and the rubber component can include any natural rubber, synthetic rubber or a combination thereof. Examples of synthetic rubbers include, but are not limited to, styrene butadiene copolymers, polyisoprene, polybutadiene, acrylonitrile butadiene styrene, polychloroprene, polyisobutylene, ethylene-propylene copolymers and ethylene-propylene-diene rubber.

[0057] The rubber composition may also contain one or more conventional additives for such compositions. Examples of these additives include carbon black, cobalt salts, stearic acid, silicon dioxide, silicic acid, sulfur, peroxides, zinc oxide, fillers, antioxidants, and softening oils.

[0058] Aspects of the present invention relate to the amount or loading of the solid phloroglucinol resin of the present invention in a vulcanizable composition. The vulcanizable composition of the present invention comprises greater than 0.5 parts by weight in one or more embodiments, greater than 1.0 parts by weight in other embodiments, greater than 1.5 parts by weight in other embodiments, and greater than 2.0 parts by weight of solid phloroglucinol resin per 100 parts by weight of rubber in other embodiments. The vulcanizable composition of the present invention comprises less than 7.0 parts by weight in these or other embodiments, less than 6.0 parts by weight in other embodiments, less than 5.0 parts by weight in other embodiments, and less than 4.0 parts by weight of solid phloroglucinol resin per 100 parts by weight of rubber in other embodiments. The vulcanizable composition of the present invention comprises about 0.5 to about 7.0 parts by weight in one or more embodiments, about 1.0 to about 6.0 parts by weight in other embodiments, about 1.5 to about 5.0 parts by weight in other embodiments, and about 2.0 to about 4.5 parts by weight of phloroglucinol resin per 100 parts by weight of rubber in other embodiments.

[0059] The rubber composition can also include one or more methylene donor components. The methylene donor component is any compound that generates formaldehyde when heated during vulcanization. Examples of such compounds are shown in US Patent No. 3,751,331, which is incorporated herein by reference. Preferred methylene donor compounds are hexamethylenetetramine, dimethylol melamine, trimethylol melamine, tetramethylol melamine, pentamethylol melamine, hexamethylol melamine and mixtures thereof. Methylol melamine can be completely or partially etherified or esterified (such as hexamethoxymethylol melamine). The methylene donor can be present in a concentration of about 0.1 to 15 parts per 100 parts of rubber or in other embodiments in a concentration of 0.1 to 10 parts per 100 parts of rubber. The ratio of methylene donor to solid phloroglucinol resin can be from 1:10 to 10:1.

[0060] As will be appreciated, the rubber components, additives, reinforcing materials and methylene donor compounds are known. Furthermore, methods of vulcanizing the compositions are known. The improvements of the present invention relate to solid phloroglucinol resins.

[0061] The rubber composition is prepared and used in the conventional manner for preparing and using such compositions. That is, the composition can be prepared by solid state mixing.

[0062] According to the foregoing, it should be understood that the rubber composition produced according to the present invention can be used for various rubber applications or rubber articles. Uncured and cured rubber composition of the present invention can be used for tire applications or for preparing parts (such as tire treads, belt layer rubber materials, sidewalls, bead compounds (bead compounds), carcasses or other regions of tires) of tires. Other applications include rubber products for engine mountings and bushings. Uncured and cured rubber composition of the present invention can be used or other examples of applications for preparation include technical or mechanical rubber articles, such as hoses, pneumatic belts and conveyor belts.

[0063] Example

[0064] To demonstrate the practice of the present invention, the following examples have been prepared and tested. However, these examples should not be considered to limit the scope of the present invention. The claims will be used to define the present invention. The abbreviation PG refers to "phloroglucinol".

[0065] PG resin example 1

[0066] 25.2 g of phloroglucinol, 47.0 g of acetone, 50.4 g of toluene, 1.1 g of thioglycolic acid and 1.2 g of 98% sulfuric acid were charged into a flask and heated to 80° C. The reaction mixture was kept at about 80° C. for 9 hours. Then, 3.8 g of 25% sodium hydroxide solution was added. The 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] PG resin example 2

[0068] 30.3 g of phloroglucinol, 69.7 g of acetone, 1.3 g of thioglycolic acid and 20.0 g of an acidic cation exchange catalyst (DIAION PK212LH, Mitsubishi Chemical Corporation) were charged into a flask and heated to 70° C. The reaction mixture was maintained at about 70° C. for 22 hours. Then, 0.8 g of a 25% sodium hydroxide solution was added. The 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.

[0069] PG resin example 3

[0070] 25.2 g of phloroglucinol, 24.4 g of acetone, 63.1 g of toluene, 1.1 g of thioglycolic acid and 20.0 g of an acidic cation exchange catalyst (DIAION PK212LH, Mitsubishi Chemical Corporation) were charged into a flask and heated to 82° C. The reaction mixture was maintained at about 82° C. for 22 hours. Then, 1.2 g of a 25% sodium hydroxide solution was added. The 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.

[0071] PG resin example 4

[0072] 80.0 g of phloroglucinol, 114.3 g of acetone and 63.5 g of an acidic cation exchange catalyst (DIAION PK212LH, Mitsubishi Chemical Corporation) were charged into a flask and heated to 70° C. The reaction mixture was maintained at about 70° C. for 24 hours. Then, 0.1 g of a 25% sodium hydroxide solution was added. The 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.

[0073] PG resin example 5

[0074] 80.0 g of phloroglucinol, 114.3 g of acetone and 63.5 g of an acidic cation exchange catalyst (DIAION PK212LH, Mitsubishi Chemical Corporation) were charged into a flask and heated to 70° C. The reaction mixture was maintained at about 70° C. for 5 hours. Then, 0.1 g of a 25% sodium hydroxide solution was added. The 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.

[0075] PG resin example 6

[0076] 25.2 g of phloroglucinol, 44.7 g of methyl ethyl ketone and 20.0 g of an acidic cation exchange catalyst (DIAIONPK212LH, Mitsubishi Chemical Corporation) were charged into a flask and heated to 80° C. The reaction mixture was kept at about 80° C. for 24 hours. Then, 0.1 g of a 25% sodium hydroxide solution was added. The 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.

[0077] PG resin example 7

[0078] 50.0 g of phloroglucinol, 72.6 g of methyl ethyl ketone and 40.0 g of an acidic cation exchange catalyst (DIAIONPK212LH, Mitsubishi Chemical Corporation) were charged into a flask and heated to 85° C. The reaction mixture was maintained at about 85° C. for 24 hours. Then, 0.1 g of a 25% sodium hydroxide solution was added. The 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.

[0079] PG resin example 8

[0080] 50.0 g of phloroglucinol, 57.0 g of methyl ethyl ketone and 40.0 g of an acidic cation exchange catalyst (DIAIONPK212LH, Mitsubishi Chemical Corporation) were charged into a flask and heated to 85° C. The reaction mixture was maintained at about 85° C. for 24 hours. Then, 0.1 g of a 25% sodium hydroxide solution was added. The 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.

[0081] PG resin example 9

[0082] 25.2 g of phloroglucinol, 61.2 g of methyl isobutyl ketone and 20.0 g of an acidic cation exchange catalyst (DIAIONPK212LH, Mitsubishi Chemical Corporation) were charged into a flask and heated to 117° C. The reaction mixture was kept at about 117° C. for 22 hours. Then, 0.1 g of a 25% sodium hydroxide solution was added. The 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.

[0083] Table 1 below provides a general description of the ingredients used to form the phloroglucinol resin. It should be understood that sulfuric acid (H2SO4) or a cation exchange catalyst was used as the acid catalyst in these examples, and some examples further used a co-catalyst (such as thioglycolic acid).

[0084] Table 1.

[0085]

[0086]

[0087] It will be appreciated that in order to provide a comprehensive analysis of the improvements provided by the above uniquely prepared solid phloroglucinol resins, the solid phloroglucinol resins available under the trade name RESIN B-19-SC was a resorcinol formaldehyde resin obtained from Sumitomo Chemical as a comparative RF resin. Thus, rubber mixes containing the phloroglucinol resins described in the Examples and Table 1 and the comparative RF resins also provided in Table 1 were prepared according to the rubber compositions shown in Table 2.

[0088] Table II: Preparation (parts by weight)

[0089] Natural rubber 100 Carbon black (HAF Black N326) 55 Zinc Oxide 8 Stearic acid 1 N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine 2 Polymerization of 1,2-dihydro-2,2,4-trimethylquinoline 1 Resin 3 Cobalt salt (22% Co) 0.45 Insoluble sulfur (20% oil) 5 N,N-Dicyclohexyl-2-benzothiazole sulfoxide amide 1 Methylene donor (HMMM, 72% active) 2.78

[0090] The rubber compositions containing each of the five phloroglucinol resins were then tested against a rubber composition containing a comparative RF resin (Example 6 - Comparative) also listed in Table 1. The rubber compositions were then tested for substantially the same properties and rubber performance characteristics.

[0091] Various physical properties and chemical analysis of solid phloroglucinol resin are provided in Table 3 below. It should be understood that when evaluating resin performance, the softening point of the resin is determined using the above-mentioned procedure, and the molecular weight and oligomer distribution are determined by GPC analysis. The resulting rubber properties based on the preparation of the vulcanized rubber as described below are also provided in Table 3. It is understood that according to ASTM D-5289, at 150°C, 0.5° radian and 1.6Hz, T'90 is measured using an Alpha Technologies MDR rheometer (MDR2000). According to the parameters obtained from the MDR2000 rheological test data, the rubber compound is cured at 150°C and 10 tons of pressure. Under lHz and 60°C conditions, G' and tanδ (an indicator of compound hysteresis or heat accumulation) are measured using a TA instrument rheometer (ARES) at 2.0% torsional shear strain, and Shore A hardness is measured according to ASTM D-2240. Unaged pull-out force and humidity aging (21 days, 85°C / 90RH) were measured according to ASTM D-2229.

[0092] Table 3 - Composition, properties and rubber properties of Examples 1-9

[0093]

[0094]

[0095]

[0096] In the comparison between the phloroglucinol resin of the present invention and the phloroglucinol resin of the comparative example, it is understood that the phloroglucinol resin of the present invention improves the mechanical properties of the cured rubber compound and provides better adhesive properties compared to the conventional resorcinol formaldehyde resin.

[0097] Furthermore, the phloroglucinol resin of the present invention has a significantly smaller Mw range compared to the comparative examples. In the present invention, the Mw is greater than 400 and less than 700 g / mol, while for the comparative examples, the Mw is greater than 700 g / mol.

[0098] Various modifications and alterations will become apparent to those skilled in the art without departing from the scope and spirit of the invention.The present invention should not be properly limited to the illustrative embodiments set forth herein.

Claims

1. Use of a solid phloroglucinol resin in the preparation of vulcanized rubber, wherein the solid phloroglucinol resin comprises a reaction product of phloroglucinol and a ketone in the presence of an acid catalyst, and the solid phloroglucinol resin comprises a resin defined by formula (II): in, n is an integer from 1 to 20; wherein R 1 and R 3 are the same or different and each form a disubstituted methylene bridge or are each a hydrogen atom, wherein R 2 is a hydrogen atom, and R 4 and R 5 are the same or different and are alkyl, The solid phloroglucinol resin has an Mw of greater than 400 g / mol and less than 700 g / mol, and a molar ratio of ketone to phloroglucinol is 2:1 to 5:

1.

2. The use according to claim 1, wherein R 4 and R 5 are all methyl groups, and wherein the disubstituted methylene bridge formed is an isopropylidene bridge.

3. The use according to claim 1, wherein R 4 is ethyl and R 5 is methyl, and wherein the disubstituted methylene bridge formed is a 2,2 disubstituted butane bridge.

4. The use according to claim 1, wherein R 4 is isopropyl and R 5 is methyl, wherein the disubstituted methylene bridge formed is a 2,2 disubstituted 4-methylpentane bridge.

5. The use according to claim 1, wherein The ketone is selected from the group consisting of acetone, methyl ethyl ketone (MEK), diethyl ketone, ethyl butyl ketone, diisobutyl ketone, methyl isopropyl ketone, diisopropyl ketone and methyl isobutyl ketone (MIBK).

6. The use according to claim 5, wherein The ketone is selected from the group consisting of acetone, methyl ethyl ketone and methyl isobutyl ketone.

7. The use according to claim 1, wherein The acid catalyst is selected from the group consisting of: an inorganic acid and an acidic cation exchange resin.

8. The use according to claim 1, wherein The solid phloroglucinol resin contains less than 40 wt % of unreacted phloroglucinol.

9. The use according to claim 1, wherein The solid phloroglucinol resin has a softening point greater than 80°C.

10. The use according to claim 1, wherein The solid phloroglucinol resin contains less than 1.5 wt % of water.

11. The use according to claim 1, wherein The solid phloroglucinol resin has a total pentamer and higher oligomer content of less than 55% according to GPC using polystyrene standards.

12. A solid phloroglucinol resin comprising a reaction product of phloroglucinol and a ketone in the presence of an acid catalyst, wherein the solid phloroglucinol resin comprises a resin defined by formula (II): in, n is an integer from 1 to 20; wherein R 1 and R 3 are the same or different and each form a disubstituted methylene bridge or are each a hydrogen atom, wherein R 2 is a hydrogen atom, and R 4 and R 5 are the same or different and are alkyl, The solid phloroglucinol resin has an Mw of greater than 400 g / mol and less than 700 g / mol, and a molar ratio of ketone to phloroglucinol is 2:1 to 5:

1.

13. A vulcanizable rubber composition comprising: a. Vulcanizable rubber; b. a curing agent; and c. The solid phloroglucinol resin according to claim 12.

14. A vulcanized rubber prepared from the vulcanizable rubber composition of claim 13.

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