Provided herein are organic solvent-based processes for the removal of rubber from non-Hevea plants such as guayule shrubs. By the use of the processes, solid purified rubber can be obtained that contains 0.05-0.5 weight % dirt, 0.2-1.5 weight % ash, and 0.1-4 weight % resin (when it has been dried so as to contain 0.8 weight % volatile matter).

Provided herein are organic solvent-based processes for the removal of rubber from non-Hevea plants such as guayule shrubs. By the use of the processes, solid purified rubber can be obtained that contains 0.05-0.5 weight % dirt, 0.2-1.5 weight % ash, and 0.1-4 weight % resin (when it has been dried so as to contain 0.8 weight % volatile matter).

Disclosed herein are process for removing color bodies from an organic solution comprising guayule resin. The processes include the use of activated carbon.

Provided are a rubber composition for tires that shows a balanced improvement in properties such as fuel economy, processability, heat aging resistance, abrasion resistance, wet-grip performance, performance on snow and ice, and handling stability, and a pneumatic tire formed from the rubber composition. The present invention relates to a rubber composition for tires, containing: a highly purified, modified natural rubber having a pH adjusted to 2-7; carbon black and/or a white filler; and a silane coupling agent represented by the following Formula (S1): ##STR00001##
wherein R.sup.1001 represents a monovalent group selected from —Cl, —Br, —OR.sup.1006, —O(O═)CR.sup.1006, —ON═CR.sup.1006R.sup.1007, —ON═CR.sup.1006R.sup.1007, —NR.sup.1006R.sup.1007, and —(OSiR.sup.1006R.sup.1007).sub.h(OSiR.sup.1006R.sup.1007R.sup.1008), wherein R.sup.1006, R.sup.1007, and R.sup.1008 are the same as or different from one another and each represent a hydrogen atom or a C1-C18 monovalent hydrocarbon group, and h represents a number whose average value is 1 to 4; R.sup.1002 represents R.sup.1001, a hydrogen atom, or a C1-C18 monovalent hydrocarbon group; R.sup.1003 represents R.sup.1001, R.sup.1002, a hydrogen atom, or the group: —[O(R.sup.1009O).sub.j].sub.0.5— wherein R.sup.1009 represents a C1-C18 alkylene group, and j represents an integer of 1 to 4; R.sup.1004 represents a C1-C18 divalent hydrocarbon group; R.sup.1005 represents a C1-C18 monovalent hydrocarbon group; and x, y, and Z are numbers satisfying the following relationships: x+y+2z=3, 0≦x≦3, 0≦y≦2, and 0≦z≦1.

Provided are a rubber composition for tires that shows a balanced improvement in properties such as fuel economy, processability, heat aging resistance, abrasion resistance, wet-grip performance, performance on snow and ice, and handling stability, and a pneumatic tire formed from the rubber composition. The present invention relates to a rubber composition for tires, containing: a highly purified, modified natural rubber having a pH adjusted to 2-7; carbon black and/or a white filler; and a silane coupling agent represented by the following Formula (S1): ##STR00001##
wherein R.sup.1001 represents a monovalent group selected from —Cl, —Br, —OR.sup.1006, —O(O═)CR.sup.1006, —ON═CR.sup.1006R.sup.1007, —ON═CR.sup.1006R.sup.1007, —NR.sup.1006R.sup.1007, and —(OSiR.sup.1006R.sup.1007).sub.h(OSiR.sup.1006R.sup.1007R.sup.1008), wherein R.sup.1006, R.sup.1007, and R.sup.1008 are the same as or different from one another and each represent a hydrogen atom or a C1-C18 monovalent hydrocarbon group, and h represents a number whose average value is 1 to 4; R.sup.1002 represents R.sup.1001, a hydrogen atom, or a C1-C18 monovalent hydrocarbon group; R.sup.1003 represents R.sup.1001, R.sup.1002, a hydrogen atom, or the group: —[O(R.sup.1009O).sub.j].sub.0.5— wherein R.sup.1009 represents a C1-C18 alkylene group, and j represents an integer of 1 to 4; R.sup.1004 represents a C1-C18 divalent hydrocarbon group; R.sup.1005 represents a C1-C18 monovalent hydrocarbon group; and x, y, and Z are numbers satisfying the following relationships: x+y+2z=3, 0≦x≦3, 0≦y≦2, and 0≦z≦1.

Provided are a method for preparing a nitrile-based rubber having an amount of ethylenically unsaturated nitrile of 34 wt % or less including preparing a polymer by performing a polymerization reaction by adding an ethylenically unsaturated nitrile-based monomer in two or more portions to a conjugated diene-based monomer, and coagulating the polymer by adding a sulfur-based coagulant to the polymer, and a nitrile-based rubber thus prepared having improved mechanical properties as well as excellent processability and low temperature characteristics.

Provided are a method for preparing a nitrile-based rubber having an amount of ethylenically unsaturated nitrile of 34 wt % or less including preparing a polymer by performing a polymerization reaction by adding an ethylenically unsaturated nitrile-based monomer in two or more portions to a conjugated diene-based monomer, and coagulating the polymer by adding a sulfur-based coagulant to the polymer, and a nitrile-based rubber thus prepared having improved mechanical properties as well as excellent processability and low temperature characteristics.

Provided herein are organic solvent-based processes for the removal of rubber from non-Hevea plants such as guayule shrubs. By the use of the processes, solid purified rubber can be obtained that contains 0.05-0.5 weight % dirt, 0.2-1.5 weight % ash, and 0.1-4 weight % resin (when it has been dried so as to contain 0.8 weight % volatile matter).

Provided herein are organic solvent-based processes for the removal of rubber from non-Hevea plants such as guayule shrubs. By the use of the processes, solid purified rubber can be obtained that contains 0.05-0.5 weight % dirt, 0.2-1.5 weight % ash, and 0.1-4 weight % resin (when it has been dried so as to contain 0.8 weight % volatile matter).

A cup lump natural rubber devoid of impurities with a size of greater than 0.5 mm and having a plasticity retention index of greater than 80 is provided. The use of such a natural rubber in a line for manufacturing a semi-finished product based on natural rubber makes it possible to ensure an improved compromise of performances which are the productivity of a line for manufacturing semi-finished products and the quality of the semi-finished products resulting from this production line.