Resinous pipe joint

1. A resin pipe joint wherein said resin pipe joint has:

a synthetic resin-made joint body including an inner cylinder portion to which an end portion of a synthetic resin-made tube is externally fittable and attachable while being flared, and an external thread portion; and

a synthetic resin-made union nut including: an internal thread portion which is screwable with said external thread portion; a seal pressing portion which is actable on a small-diameter portion of a flaring changing region in a flared portion of said tube, said flared portion being externally fitted to said inner cylinder portion; a slipping-off prevention pressing portion which is actable on a large-diameter portion of said flaring changing region; and a pressing inner peripheral portion which is externally fittable to a flared straight portion of said flared portion, said flared straight portion surrounding a constant-diameter straight barrel cylinder portion, and

said resin pipe joint is set so that, by a screw advancement of said union nut in a direction of an axis of sad joint body, the screw advancement being caused by screwing said internal thread portion to said external thread portion in a state where said tube is externally fitted and attached to said inner cylinder portion and said flared portion is formed, said pressing inner peripheral portion is externally fitted to said flared straight portion, a portion of said large-diameter portion of said flaring changing region is pressed in the direction of the axis by said slipping-off prevention pressing portion, a diameter of said portion being larger than a diameter of said inner cylinder portion, and said small-diameter portion of said flaring changing region is pressed in the direction of the axis by said seal pressing portion, and

a pressing face is formed on the slipping-off prevention pressing portion, an inner diameter of the pressing face is formed to be larger than a maximum diameter of an outer peripheral face of the inner cylinder portion and smaller than a diameter of an inner peripheral face of the pressing inner peripheral portion, the pressing face being perpendicular to the axis.

2. A resin pipe joint according to claim 1 , wherein said inner cylinder portion is formed by an end-tapered cylinder portion which causes said tube to be gradually flared, and said straight barrel cylinder portion which is formed in succession to a large-diameter side of said end-tapered cylinder portion, and said flaring changing region of said tube is a portion which is put over said end-tapered cylinder portion.

3. A resin pipe joint according to claim 2 , wherein said straight barrel cylinder portion is extended to an end of said inner cylinder portion, said end being opposite to said end-tapered cylinder portion.

4. A resin pipe joint according to claim 3 , wherein both said joint body and said union nut are made of a fluorine resin.

5. A resin pipe joint according to claim 2 , wherein said inner cylinder portion has a small-diameter straight barrel cylinder portion which is formed in a side of said straight barrel cylinder portion in a state where a diameter is smaller than said straight barrel cylinder portion, said side being opposite to said end-tapered cylinder portion.

6. A resin pipe joint according to claim 5 , wherein both said joint body and said union nut are made of a fluorine resin.

7. A resin pipe joint according to claim 1 , wherein both said joint body and said union nut are made of a fluorine resin.

8. A resin pipe joint according to claim 2 , wherein both said joint body and said union nut are made of a fluorine resin.

9. A resin pipe joint wherein said resin pipe joint has:

a synthetic resin-made joint body including an inner cylinder portion to which an end portion of a synthetic resin-made tube is externally fittable and attachable while being flared, and an external thread portion; and

a synthetic resin-made union nut including: an internal thread portion which is screwable with said external thread portion; a seal pressing portion which is actable on a small-diameter portion of a flaring changing region in a flared portion of said tube, said flared portion being externally fitted to said inner cylinder portion; a slipping-off prevention pressing portion which is actable on a large-diameter portion of said flaring changing region; and a pressing inner peripheral portion which is externally fittable to a flared straight portion of said flared portion, said flared straight portion surrounding a constant-diameter straight barrel cylinder portion, and

said resin pipe joint is set so that, by a screw advancement of said union nut in a direction of an axis of said joint body, said screw advancement being caused by screwing said internal thread portion to said external thread portion in a state where said tube is externally fitted and attached to said inner cylinder portion and said flared portion is formed, said pressing inner peripheral portion is pressingly contacted with and externally fitted to said flared straight portion, said large-diameter portion of said flaring changing region is pressed in the direction of the axis by said slipping-off prevention pressing portion, and said small-diameter portion of said flaring changing region is pressed in the direction of the axis by said seal pressing portion, and

a pressing face is formed on the slipping-off prevention pressing portion, a an inner diameter of the pressing face is formed to be larger than a maximum diameter of an outer peripheral face of the inner cylinder portion and smaller than a diameter of an inner peripheral face of the pressing inner peripheral portion, the pressing face being perpendicular to the axis.

10. A resin pipe joint according to claim 9 , wherein said pressing inner peripheral portion is pressingly contacted with and externally fitted to said flared straight portion in a degree in which a radial gap is not formed between said pressing inner peripheral portion and said flared straight portion, and co-rotation of said flared portion due to fastening of said union nut does not occur.

11. A resin pipe joint according to claim 10 , wherein said inner cylinder portion is formed by an end-tapered cylinder portion which causes said tube to be gradually flared, and said straight barrel cylinder portion which is formed in succession to a large-diameter side of said end-tapered cylinder portion, and said flaring changing region of said tube is a portion which is put over said end-tapered cylinder portion.

12. A resin pipe joint according to claim 11 , wherein said straight barrel cylinder portion is extended to an end of said inner cylinder portion, said end being opposite to said end-tapered cylinder portion.

13. A resin pipe joint according to claim 12 , wherein both said joint body and said union nut are made of a fluorine resin.

14. A resin pipe joint according to claim 11 , wherein both said joint body and said union nut are made of a fluorine resin.

15. A resin pipe joint according to claim 10 , wherein both said joint body and said union nut are made of a fluorine resin.

16. A resin pipe joint according to claim 9 , wherein said inner cylinder portion is formed by an end-tapered cylinder portion which causes said tube to be gradually flared, and said straight barrel cylinder portion which is formed in succession to a large-diameter side of said end-tapered cylinder portion, and said flaring changing region of said tube is a portion which is put over said end-tapered cylinder portion.

17. A resin pipe joint according to claim 16 , wherein said straight barrel cylinder portion is extended to an end of said inner cylinder portion, said end being opposite to said end-tapered cylinder portion.

18. A resin pipe joint according to claim 17 , wherein both said joint body and said union nut are made of a fluorine resin.

19. A resin pipe joint according to claim 16 , wherein both said joint body and said union nut are made of a fluorine resin.

20. A resin pipe joint according to claim 9 , wherein both said joint body and said union nut are made of a fluorine resin.