Tackifier for rubber compositions

Abstract

A tackifier contains a resin with repeating units of formula I

##STR00001##

wherein R.sup.1 is a linear or branched alkylene group with 1 to 10 carbon atoms and R.sup.2 is a linear or branched, saturated or unsaturated aliphatic hydrocarbon group with up to 20 carbon atoms. The tackifier also contains an amino resin with on average at least two hydroxy or ether groups per molecule.

Claims

1: A tackifier, comprising: a resin with repeating units of formula I ##STR00006## wherein R.sup.1 is a linear or branched alkylene group with 1 to 10 carbon atoms and R.sup.2 is a linear or branched, saturated or unsaturated aliphatic hydrocarbon group with up to 20 carbon atoms, and an amino resin with on average at least two hydroxy or ether groups per molecule.

2: The tackifier according to claim 1, wherein R.sup.1 in formula I is CH.sub.2, HC—CH.sub.3, or H.sub.2C—CH.sub.2.

3: The tackifier according to claim 1, wherein R.sup.2 in formula I is a linear or branched, saturated or unsaturated aliphatic hydrocarbon group with 4 to 10 carbon atoms.

4: The tackifier according to claim 1, wherein the resin with repeating units of formula I is a resin which is obtainable by reacting acetylene and para tertiary butyl phenol.

5: The tackifier according to claim 1, wherein the amino resin is an amino resin with on average at least two ether groups per molecule.

6: The tackifier according to claim 1, wherein the amino resin is an amino resin with on average at least two methyl ether groups per molecule.

7: The tackifier according to claim 1, wherein the amino resin is a melamine-formaldehyde resin.

8: The tackifier according to claim 7, wherein the melamine-formaldehyde resin comprises on average 1 to 3 melamine rings per molecule.

9: The tackifier according to claim 1, wherein the tackifier comprises 0.5 to 30 parts by weight of the amino resin per 100 parts by weight of the resin with repeating units of formula I.

10: The tackifier according to claim 1, wherein the tackifier comprises a plasticizer.

11: The tackifier according to claim 10, wherein the plasticizer is selected from the group consisting of a linear or branched, saturated or unsaturated aliphatic hydrocarbon; an oligomer obtained by reacting an unsaturated aliphatic hydrocarbon with an unsaturated dicarboxylic acid, a dicarboxylic acid anhydride, or a dicarboxylic acid amide; a saturated or unsaturated fatty alcohol; a saturated or unsaturated fatty acid; an ester of a saturated or unsaturated fatty alcohol with a mono-, di-, tri- or tetra carboxylic acid, including a saturated or unsaturated fatty acid; an ester of a saturated or unsaturated fatty acid with an alcohol other than a saturated or unsaturated fatty alcohol; and a saturated or unsaturated fatty acid anhydride or amide.

12: The tackifier according to claim 10, wherein the tackifier comprises 0.1 to 50 parts by weight of the plasticizer per 100 parts by weight of the resin with repeating units of formula I.

13: A rubber composition, comprising the tackifier according to claim 1.

14: The rubber composition according to claim 13, wherein the rubber composition comprises 0.1 to 50 parts by weight of tackifier per 100 parts by weight of rubber.

Description

EXAMPLES

Materials Used:

[0117] Resin with Repeating Units of Formula I

Koresin® of BASF

[0118] Koresin is a resin which is obtainable by reacting acetylene and para tertiary butyl phenol.

SP 1068:

[0119] An alkyl-phenol-formaldehyde resin obtained by reacting para tertiary butyl phenol and para tertiary octyl phenol with formaldehyde (marketed by SI Group)

PF 7001:

[0120] An alkyl-phenol-formaldehyde resin obtained by reacting para tertiary butyl phenol with formaldehyde (marketed by Shandong Laiwu Runda)

SC 204:

[0121] An alkyl-phenol-formaldehyde resin obtained by reacting para tertiary butyl phenol with formaldehyde

Amino Resin:

[0122] The following melamine-formaldehyde resins (shortly MF resins) have been used:

MF 1:

[0123] a melamin-formaldehyde resin with 5.7 methylol groups per melamine, whereby 4.7 methylol groups per melamine are etherified with methanol

MF 2:

[0124] a melamin-formaldehyde resin with 4.1 methylol groups per melamine, whereby 3.0 methylol groups per melamine are etherified with methanol

[0125] For comparison, paraformaldehyde was used as an alternative to melamine-formaldehyde resins

Plasticizer

[0126] 1-Octadecanol (shortly “Octa” in some tables) has been used as plasticizer.

Preparation of the Tackifier:

[0127] Koresin® (200 g), optionally the plasticizer 1-octadecanol and the melamine-formaldehyde resin were placed in a flask equipped with a condenser and mechanical stirrer and heated to 180° C. The Mixture was then stirred for one hour and then cooled down. After the melt had cooled down and solidified the material was removed and analyzed via GC (to determine the content of tertiary butylphenol, shortly tBP), GPC (to determine the number average molecular weight Mn, the weight average molecular weight Mw and the polydispersity PD, tetrahydrofuran used as solvent) and DSC (Differential scanning calorimetry, heating rate 10K/min up to 200° C.). The glass-transition temperatures (Tg) were derived from the DSC data.

Tackifiers 1-4

[0128] Further tackifiers 2 to 4 have been prepared and analyzed according to the procedure described above. Tackifier 1 is simply Koresin.

[0129] Table 1 shows the compositions of the tackifiers and table 2 some analytical data of the tackifiers

TABLE-US-00001 TABLE 1 compositions of the tackifiers Koresin 1-octadecanol MF 1 tackifiers parts by weight parts by weight parts by weight 1 100 2 100 7 3 3 100 10 6 4 100 10 9

TABLE-US-00002 TABLE 2 analytical data of the tackifiers content of Mn, Mw, Tg, tackifiers tBP % g/mol g/mol PD ° C. 1 1.33 1222 2016 1.7 99 2 0.21 1654 3046 1.8 98.3 3 0.09 1832 4495 2.5 98.3 4 0.04 2108 7507 3.6 108.6

Determination of Tackiness

[0130] A rubber formulation with the following composition (in parts by weight) was used:

TABLE-US-00003 SBR rubber 100 Process oil 13 Carbon black 45 Talc 17 Polybutadiene 17

[0131] The above rubber formulation was compounded on a roller mill with 5 parts by weight of the samples od table 1. After the addition of the tackifier the temperature of the mixture was raised to 120° C. for 3 minutes to ensure a homogenous dispersion of the resin.

[0132] Test samples prepared from the finished compound were stored at 23° C. and a relative humidity of 50% for the times given in Table 2.

[0133] The tack of the test samples was determined after different storage times as listed in Table 3.

[0134] In particular, the tack of these samples was measured with a “Ketjen Tackmeter”. Two test samples which had the form of strips are pressed together with a force of 20 N/cm.sup.2 for 30 seconds. Between the samples there was a Teflon foil with a window to ensure a defined contact area. After release of the force and another 10 seconds for relaxation the strips were separated. The force to separate the two rubber strips from each other was measured in newton (N). A high force corresponds to a high tackiness of the test samples.

TABLE-US-00004 TABLE 3 tack Storage tackifier 1 (days) (Tage) (Koresin, Only) tackifier 2 tackifier 3 tackifier 4 0 21.70 18.35 26.30 19.30 1 35.85 33.00 30.10 32.40 3 23.65 17.10 19.50 22.50 6 16.48 16.60 17.70 15.90 10 13.05 12.30 13.40 10.40

Tackifiers 5 to 11

[0135] Further tackifiers 5 to 11 have been prepared and analyzed according to the procedure described above; however, Koresin has been replaced by other commercially available resins with repeating units of formula I.

TABLE-US-00005 TABLE 4 composition and analytical data of the tackifiers composition alkylphenol- Octa MF 1 formaldehyd parts parts tBP Tg Tackifier resin by weight by weight % tOP Mn Mw PD ° C. 5 SP 1068 3.7 870 1428 1.6 52.0 6 SP 1068 7 6 0.07 1.75 1652 4033 2.4 57.6 7 PF 7001 1.8 1165 1850 102.0 8 PF 7001 9 5 0.14 1580 3540 2.2 90.2 9 SC 204 3.07 84.0 10 SC 204 9 5 0.54 1414 2259 1.6 101.1 11 SC 204 9 9 0.39 3442 3442 1.9 112.5 tOP: tertiary octyl phenol TBP: tertiary butyl phenol The parts by weight of Octadecanol and MF 1 are based on 100 parts by weight of the alkylphenol-formaldehyde resin

Tackifiers 12 to 16

[0136] Further tackifiers 12 to 16 have been prepared and analyzed according to the procedure described above. However, no plasticizer (1-octadecanol) has been used and the components have been heated to 200° C. instead of 180° C. All tackifiers are based on Koresin; the parts by weight of the amino resin is based on 100 parts by weight of Koresin.

TABLE-US-00006 TABLE 5 composition and analytical data of the tackifiers Koresin, Parts by weight parts by Amino resin of amino resin Tg tackifiers weight or other resin or other resin tBP % ° C. 12 100 MF1 3 0.27 131.0 13 100 MF1 5 0.09 138.5 14 100 MF1 7 0.05 150.4 15 100 MF2 3 0.40 124.6 16 100 Para- 5 0.83 132.3 formaldehyd

Tackifiers 17 to 23

[0137] Further tackifiers 17 to 23 have been prepared and analyzed according to the procedure described above. However, the reaction temperature has been varied between 180 and 230° C. and the reaction time has been varied between 1 and three hours.

TABLE-US-00007 TABLE 6 composition and analytical data of the tackifiers Reaction Reaction tack- Temp time Octadecanol MF1 tBP Tg ifier (° C.) (h) (%) (%) % ° C. 17 200 1 3 5 0.07 129.0 18 230 2 3 5 0.25 98.0 19 200 1 5 5 0.08 116.9 20 230 3 5 5 0.25 110.3 21 200 1 5 7 0.04 118.3 22 230 3 5 7 0.25 106.5 23 180 1 7 9 0.02 105.9

[0138] Tackifiers 1, 5, 7, 9 and 16 are for comparison.