Item of seating furniture, in particular an office chair

1. An item of seating furniture, comprising:

a horizontal seat member;

a seat carrier for supporting said horizontal seat member;

a vertical backrest;

a backrest carrier for supporting said vertical backrest, said backrest carrier constructed in a substantially U-shaped manner with two vertically orientated members and a horizontal upper member, said vertically oriented members having seat-side free ends;

horizontally aligned retention arms extending from said seat-side free ends and extending below said horizontal seat member and at least partially laterally engaging around said seat carrier, said backrest carrier and said horizontally aligned retention arms produced as a unitary part from a deformable material which is elastic so as to be bendable; and

rotary joints including a first rotary joint and a second rotary joint disposed along at least one rotation axis extending below said horizontal seat member, said rotary joints allowing a lateral tilting movability of said vertical backrest with respect to said seat carrier, said first and second rotary joints are disposed spaced apart from each other along the rotation axis.

2. The item of seating furniture according to claim 1 , further comprising a rocker arm disposed between said vertically oriented members, said rocker arm being directed transversely relative to the rotation axis.

3. The item of seating furniture according to claim 2 , wherein said rocker arm is formed from two half-shells which are stacked vertically one over the other.

4. The item of seating furniture according to claim 3 , wherein said half-shells of said rocker arm are screwed to each other.

5. The item of seating furniture according to claim 4 , further comprising a positioned covering shell, a screwing of said half-shells is concealed by means of said positioned covering shell.

6. The item of seating furniture according to claim 2 , wherein said rocker arm is secured to said seat carrier.

7. The item of seating furniture according to claim 1 wherein:

said first rotary joint is a ball joint;

said horizontally aligned retention arms have a joint-socket-shaped receiving member; and

said seat carrier having a joint-head-shaped continuation which engages in said joint-socket-shaped receiving member of said horizontally aligned retention arms.

8. The item of seating furniture according to claim 2 wherein:

said second rotary joint is a hinge joint;

said rocker arm has a groove-shaped receiving member; and

said horizontally aligned retention arms each have a roller-shaped continuation which is surrounded in each case by said groove-shaped receiving member of said rocker arm.

9. The item of seating furniture according to claim 2 , further comprising an actuatable blocker for impeding or blocking the lateral tilting movability of said backrest carrier.

10. The item of seating furniture according to claim 9 , wherein said actuatable blocker is constructed to block a movability of said second rotary joint.

11. The item of seating furniture according to claim 9 ,

further comprising a resiliently loaded blocking block; and

wherein said actuatable blocker is disposed in said rocker arm and has a blocking pin which is coupled to said second rotary joint in a pivotably secure manner and which can be moved into in a forming-locking engagement with said resiliently loaded blocking block.

12. The item of seating furniture according to claim 1 , wherein the item of seating furniture is an office chair.

13. The item of seating furniture according to claim 1 , further comprising a rocker arm disposed between said horizontally aligned retention arms, said rocker arm being directed transversely relative to the rotation axis.