JPH07108951B2 - Polyphenylene sulfide resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyphenylene sulfide resin composition that can be used for sliding parts such as sliding bearings, cams and bearing cages. More specifically, the present invention relates to a polyphenylene sulfide resin composition having excellent heat resistance and friction / wear properties, and having little damage to the metal of the mating material and having a well-balanced mechanical strength.

(Prior Art) Recently, a large amount of injection-moldable heat-resistant plastic materials have been used for sliding parts such as bearings in terms of weight reduction and productivity. Polyphenylene sulfide (hereinafter referred to as PPS) is known as a thermoplastic resin having excellent heat resistance and chemical resistance. In addition to this, fibrous materials such as glass fiber and carbon fiber, polytetrafluoroethylene (hereinafter referred to as PTFE) In some cases, a composition for a sliding material containing a fluororesin, a lubricant such as graphite / molybdenum disulfide, or a lubricating oil such as mineral oil / synthetic oil is well known. However, when the composition is used for a bearing or the like, the mating material may be damaged by the fibrous material, resulting in a rough wear behavior, a high friction coefficient, and abrasion on the plastic side may be significantly accelerated. These undesired phenomena are particularly remarkable when a soft metal such as stainless steel or aluminum is used as the mating material. In addition, the combination of solid lubricants and lubricating oils is not sufficient in terms of frictional characteristics, and can only be used under low PV values.

On the other hand, a composition comprising PPS, oxybenzoyl polyester and a fluororesin as disclosed in JP-A-57-167348 is a composition in which the above problems are improved. This is obtained by adding 30 to 300 parts by weight of PPS to 100 parts by weight of a composition containing an oxybenzoyl polyester and a fluororesin in a weight ratio of 10:90 to 90:10, and It has excellent wear characteristics and hardly damages soft materials.

(Problems to be Solved by the Invention) However, PPS used in the composition is commercially available as Ryton (registered trademark) from Philippe Petroleum Co. in the United States, and heat treatment at high temperature or By intentionally adding a cross-linking agent or a branching agent, a cross-linking or branching structure is partially introduced into the molecular structure (hereinafter referred to as a branched PPS resin).
That is, a relatively low molecular weight PPS is subjected to a heat treatment in air or an oxygen-containing gas at a high temperature for 1 to 24 hours to cause a crosslinking reaction to give a high molecular weight product, or a trivalent or higher polyhaloaromatic compound is used as a crosslinking agent High molecular weight is used as a branching agent.

For this reason, even if the melting point of PPS (about 290 ° C) does not result in a molten state and granular oxybenzoyl polyester or PTFE, which does not show a reinforcing effect like fibrous substances, is added to branched PPS, the amount added At the same time, the mechanical strength is significantly reduced. The wear properties of the composition improve with the amount of oxybenzoyl polyester added, and the friction properties improve with the amount of PTFE added (lower friction coefficient). In particular, when the amount of PTFE added exceeds 30% by weight, the friction characteristics become good. However, when the total amount of the oxybenzoyl polyester and PTFE added exceeds 50% by weight, the composition becomes extremely brittle, resulting in extremely poor moldability, and sliding parts produced from this are extremely fragile. It is easily damaged and
Even if it is not damaged, there is a problem in that a part of the sliding portion is lost during sliding, which promotes wear of the sliding surface.

An object of the present invention is to improve the brittleness of a composition comprising PPS, oxybenzoyl polyester and a fluororesin having excellent friction and wear characteristics, and to provide a composition having more excellent friction and wear characteristics. .

(Means for Solving Problems) As a result of diligent studies on the above problems, the present inventors have found that PP having a linear molecular chain grown to a high molecular weight in the polymerization stage.
Using S (hereinafter referred to as linear PPS), this linear PPS30
It has been found that a resin composition consisting of ˜85 wt%, oxybenzoyl polyester 5˜30 wt% and fluororesin 10˜60 wt% can solve the above problems.

That is, the present invention is a linear polyphenylene sulfide resin having a melt viscosity of 1000 poise or more measured at 310 ° C. and a shear rate of 200 (sec) ⁻¹ , 30 to 85% by weight, oxybenzoyl polyester, 5 to 30% by weight, and a fluororesin. A polyphenylene sulfide resin composition comprising 10 to 60% by weight.

The linear PPS used in the present invention is manufactured by the method disclosed in JP-A-617332, JP-A-61-66720, etc., and heat treatment at high temperature after polymerization or 1000 when the melt viscosity, which is a measure of the molecular weight, is measured at a shear rate of 200 (sec) ^-1 at 310 ° C without adding a cross-linking agent or branching agent.
It has more than a poise. Such PPS is "Fortron (registered trademark) KPS" from Kureha Chemical Industry Co., Ltd.
Can be obtained as.

The oxybenzoyl polyester used in the present invention generally has a repeating unit represented by the following formula (I).

As a method for producing these polyesters, Japanese Patent Publication No. 46-67
No. 96, Japanese Patent Publication No. 47-47870, a method of using a high boiling point solvent as a polymerization medium and JP-A No. 54-46.
There is a bulk polymerization method in which a solvent is not substantially used in a polymerization system as seen in Japanese Patent Application Laid-Open No. 287 and Japanese Patent Application Laid-Open No. 54629/1979. This is Econol (registered trademark) E101 (manufactured by Sumitomo Chemical Co., Ltd.). ) Is marketed under the brand name.

Examples of the fluororesin used in the present invention include polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer, polytrichlorofluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and the like. Yes, but PTFE is particularly preferred. Among PTFE, lubricant grade PTFE powder having an average particle size of less than 20 μm is preferable, and examples of commercially available products include Fluon (registered trademark) L169 and L17.
0, L171 (manufactured by ICI); Lubron (registered trademark) L-2, L
-5, LD-1 (manufactured by Daikin Industries, Ltd.); Teflon (registered trademark) TLP-10, TLP-10F-1 (manufactured by DuPont) and the like.

The compounding amount is linear PPS 30-85% by weight, oxybenzoyl polyester 5-30% by weight, and fluororesin 10-
It is effective to add 60% by weight (15 to 70% by weight of the total resin composition as the total amount of oxybenzoyl polyester and fluororesin). Particularly, the oxybenzoyl polyester content is 10 to 25% by weight, and the fluororesin content is 20%.
When the content is up to 50% by weight, the friction and wear characteristics are excellent and preferable.

That is, when the total amount of the oxybenzoyl polyester and the fluororesin exceeds 70% by weight of the total resin composition and the PPS is less than 30% by weight, the mixing is insufficient and a uniform composition cannot be obtained. Loses its fluidity and makes molding difficult.
Further, when the total amount of the oxybenzoyl polyester and the fluororesin is less than 15% by weight of the total resin composition, the friction and wear characteristics are not sufficient.

Even if the total amount of oxybenzoyl polyester and fluororesin is 15 to 70% by weight, when the amount of oxybenzoyl polyester is less than 5% by weight, abrasion resistance and creep resistance are not sufficient, Even if compounded in excess of 30% by weight, in terms of wear resistance and creep resistance, the effect of 5 to 30% by weight or more is not observed and the formability and surface condition deteriorate. on the other hand,
When the amount of the fluororesin is less than 10% by weight, the frictional properties are insufficient, and when it exceeds 60% by weight, melt-kneading becomes difficult, and a uniformly dispersed composition cannot be obtained.

The mixing means of the raw material resin component of the resin composition of the present invention is not particularly limited. It is possible to supply PPS, oxybenzoyl polyester and fluororesin separately to the melt mixer, and to pre-mix these raw material resin components with a Henschel mixer, ribbon blender, etc. before supplying them to the melt mixer. You can also do it.

Incidentally, for the resin composition of the present invention, within a range that does not impair the object of the present invention, processing stability, for the purpose of improving the surface properties and coloring, an appropriate amount of a stabilizer, a fluidity improving agent as necessary. , Surface modifiers, colorants, and other resins may be added as appropriate.

(Function) Even if the oxybenzoyl polyester or PTFE, which does not become a molten state even at the melting point of PPS and does not show a reinforcing effect like a fibrous substance, is added to the linear PPS, the decrease in mechanical strength is small, and The reason why it is not as brittle as when using a branched PPS is that linear PPS has a larger entanglement between molecular chains than a branched PPS with the same molecular weight, and is itself tough. it is conceivable that.

(Examples) Examples of the present invention will be shown below, but the present invention is not limited thereto.

Example 1, Comparative Example 1 A thrust wear test was carried out by preparing test pieces of the compositions having the proportions shown in Table 1 below.

Each composition is a straight-chain PPS resin by Kureha Chemical Industry Co., Ltd.
"Fortron (registered trademark) KPS T-230"
"Ryton (registered trademark) R-6" manufactured by Philippe Petroleum Co., Ltd. as PPS resin, "Teflon (registered trademark) TLP-10" manufactured by Mitsui DuPont Fluorochemical Co., Ltd., which is PTFE resin powder as fluororesin, and oxybenzoyl polyester. Sumitomo Chemical Co., Ltd.'s "Econol (registered trademark) E-101 (S type)" is used, and each resin is manufactured by HAAKE-BUCHLER INSTRUMENT INC. At a ratio shown in Table 1. Kneading machine HAAKE-RHEOCORD SYSTEM 40
It was obtained by kneading for 20 minutes at 300 ° C. The obtained resin composition is heated and pressed at 300 ° C. to have a diameter of 8 mm and a thickness of 1 mm.
The above disc-shaped test piece was compression-molded. Since the composition of Comparative Example 1-B was brittle, a test piece could not be molded.

Thrust wear tests were performed on the test pieces of Examples 1-A, 1-B, 1-C and Comparative Example 1-A using a thrust wear tester manufactured by NSK Ltd. Thrust wear test
Each test piece was fixed stationary and the SUS416 shaft was rotated at 49
The test piece was pressed against each test piece at 0 rpm, a load of 300 g · f, and unlubricated, and the wear depth (μm) from the end surface on the pressing surface side was measured. The shaft has a diameter of 6 mm and a length of 66 mm, and the pressing tip has a curved surface of 2.5 mm sphere, and the surface roughness of this curved surface is Ra = 0.05 to 0.07 μm.

FIG. 1 shows the thrust test results for each test piece except Comparative Example 1-B in which the test piece could not be produced, and is a plot of the relationship between the test time and the wear depth (μm).

In FIG. 1, Comparative Example 1 which is a branched PPS resin composition
-A reaches a wear depth of 38 μm for 50 hours, but it is less than 30 μm even in 1000 hours in Examples 1-B and 1-C which are linear PPS resin compositions. Example 1-
From the comparison between A and Comparative Example 1-A, it can be seen that the wear characteristics are also improved by using the linear PPS resin. Linear
Since the PPS resin does not have branched chains or crosslinked parts, entanglement between molecular chains is also efficient, and it is considered that brittleness is suppressed even if PTFE resin or filler is introduced due to its high toughness. . In addition, PTFE is 30% by weight for branched PPS resin
If it is added in excess of 30%, the moldability becomes poor and it cannot be used in practice. However, in the case of the linear PPS resin, if it is added in excess of 30% by weight, the moldability is not affected and the wear characteristics are remarkably improved.

Example 2 and Comparative Example 2 Specimens were prepared from the compositions in the proportions shown in Table 2 below, and friction / wear tests were conducted.

The test piece was obtained by kneading the same material as in Example 1 by the same method and then compression-molding it at 300 ° C. by hot pressing. The test piece was formed into a disk shape having a diameter of 30 mm and a thickness of 2 mm. The composition of Comparative Example 2-B is similar to Comparative Example 1-B in that it is brittle, but the thickness of the test piece is 2 mm, which is twice as large as that of Comparative Example 1-B. It was

Using each test piece, a friction / wear test was carried out by a commonly-used Suzuki / Matsubara friction and wear tester (MODEL-III-E) manufactured by Toyo Baldwin Co., Ltd. The test shaft was made of bearing steel (SUJ-2). Shaft outer diameter 25 mm, inner diameter 2
It has a cylindrical shape of 0 mm and a height of 15 mm, and has a quenching and tempering hardness HV> 700.
After heat treatment to nickel plating treatment
Finished to 0.5 μm. The test conditions are: thrust surface pressure of shaft 11.8kgf / cm ² , sliding speed 1.25m / min., Temperature 130
It was ℃.

The dynamic friction coefficient, the wear coefficient, and the wear amount of the mating material were measured 50 hours after the start of the test. The amount of wear of the mating material was measured as the dimensional reduction amount (μm) in the height direction of the shaft.
The measurement results are also shown in Table 2 above.

Example 2-A and Comparative Example 2-A, Example 2-B and Comparative Example 2
Comparing -B with each other, it can be seen that the composition using the linear PPS resin is superior in the dynamic friction coefficient, the wear coefficient, and the wear depth of the mating material. In addition, the amount of PTFE resin powder is 30
In Example 2-B in which the content exceeds the weight%, the friction and wear characteristics are remarkably improved.

Further, comparing Example 2-B with Example 2-C, when the addition amount of oxybenzoyl polyester, which is an abrasion resistance component, is reduced to 5% by weight, the addition amount of the linear PPS resin having an abrasion resistance effect is large. Nevertheless, the wear coefficient increased, showing a value close to that of Comparative Example 2-A using a branched PPS resin in the matrix. Therefore, unless the lower limit of the amount of oxybenzoyl polyester added is at least 5% by weight, the wear resistance improving effect of the linear PPS resin composition of the present invention is sufficient as compared with the conventional branched PPS resin composition. I see that it doesn't appear in.

Example 3, Comparative Example 3 A test piece was injection-molded from the composition in the proportions shown in Table 3 below, and a friction / wear test was conducted.

The same material as in Example 1 was kneaded and extruded into pellets by a twin-screw extruder (MODEL PCM-30) manufactured by Ikegai Iron Works Co., Ltd., and then an injection molding machine (MODEL SI manufactured by Technoplus Co., Ltd.).
M4749) injection molded into a static friction test piece with an outer diameter of 16 mm, an inner diameter of 12 mm and a length of 10 mm (hereinafter referred to as test piece X),
A test piece for friction and wear (hereinafter referred to as test piece Y) having an outer diameter of 25 mm, an inner diameter of 20 mm and a length of 10 mm was prepared. The composition of Comparative Example 3-B could not be injection molded.

The static friction test was performed using a tilt table static friction measuring instrument manufactured by NSK Ltd. with an SUS304 shaft having an outer diameter of 11.9 mm and a surface roughness of 0.2 μmHmax as a mating material. The shaft was inserted into the inner hole of the test piece X, and a static friction coefficient was measured by applying a pressure of 62.5 g · f / cm ^{2 to} the contact surface, which is a sliding surface. That is, the shaft is inserted into the inner diameter of the test piece X, and the weight of the outer diameter is 75.0
After inserting the cylindrical weight of g, gradually incline it from the horizontal state, and calculate the static friction coefficient from the inclination angle when the shaft begins to slide.

On the other hand, the dynamic friction coefficient and the wear coefficient of the test piece Y were measured using the Suzuki-Matsubara friction and wear tester described in Example 2. As the mating material, a sleeve made of aluminum (A-5056) having the same dimensions as the test piece Y was finished to have a surface roughness of 1 μmHmax and used. The test conditions were a thrust surface pressure of 3.5 kg · f / cm ² , a sliding speed of 10 m / min., And a temperature of 130 ° C. The dynamic friction coefficient and wear coefficient of the test piece Y were measured 20 hours after the start of the test.

Table 3 also shows the measurement results of the static friction coefficient of the test piece X, the dynamic friction coefficient and the wear coefficient of the test piece Y.

From the test results shown in Table 3, it can be seen that the friction and wear characteristics of Example 3-B in which 40% by weight of the PTFE resin powder is added are remarkably improved.

Further, in Example 3-C in which the added amount of oxybenzoyl polyester, which is an abrasion resistant component, was reduced to 5% by weight, the abrasion coefficient was increased, and the added amount of oxybenzoyl polyester was at least 5% by weight or more as in Example 2. Without it, it can be confirmed that the wear resistance improving effect of the linear PPS resin composition of the present invention does not sufficiently appear as compared with the conventional branched PPS resin composition.

Example 4, Comparative Example 4 A test piece was injection-molded from the composition in the proportions shown in Table 4 below, and an annular crushing test was conducted.

The composition was kneaded in the same manner as in Example 3 and injection-molded to prepare a cylindrical test piece having an outer diameter of 16 mm, an inner diameter of 12 mm and a length of 10 mm.

Each test piece was subjected to an annular crushing test by applying a load to the side surface of the test piece by a push-pull stand (H-12 type) manufactured by Imada Seisakusho, and the annular crushing load value at break was measured. It is also shown in Table 4. The test condition is a deformation rate of 8 mm /
min., temperature was 25 ° C.

Comparing Example 4-A with Comparative Example 4-A and Example 4-B with Comparative Example 4-B, the composition using the linear PPS resin was better at any annular crush load value. It turns out to be excellent.

Furthermore, comparing Example 4-B with Comparative Example 4-A, the linear PPS was used although the ratio of [matrix / filler (PTFE resin powder + oxybenzoyl polyester resin powder)] was small. It can be seen that the composition exhibits even higher ring crush values than compositions using branched PPS resin with a larger [matrix / fill] ratio.

Example 5, Comparative Example 5 A test piece was injection-molded from the composition in the proportions shown in Table 5 below, and a shear fracture test on the collar portion was performed.

The test piece was kneaded using the same material as in Example 3 by the same method, and was molded by injection molding into a cylindrical shape with a single-sided flange.
The test piece had an outer diameter of 14 mm, an inner diameter of 10 mm, a length (including a collar portion) of 10 mm, a collar portion outer diameter of 17 mm, and a collar portion thickness of 2 mm.

Each test piece was fixed to the push-pull stand (H-12 type) described in Example 4 so that the collar surface was on the upper side, and the sleeve portion was made of an aluminum sleeve having an outer diameter of 17 mm, an inner diameter of 15 mm, and a length of 10 mm. Then, the collar was subjected to a shear fracture test so that the load was uniformly applied around the collar of the test piece. The test conditions were a deformation rate of 8 mm / min and a temperature of 25 ° C., and the load at the time of shear failure of the flange portion of the test piece was measured. The measurement results are shown in Table 5 above.
Also described in.

Comparing Example 5-A with Comparative Example 5-A, it can be seen that the composition using the linear PPS resin is superior in the shear fracture load on the collar portion.

Further, from the comparison between Example 5-B and Comparative Example 5-A, it was found that
In the case of a composition using PPS resin, the ratio of [matrix / filling (PTFE resin powder + oxybenzoyl polyester resin powder)] is as small as 1/1, but it is larger than 3/2 [matrix / filling]. It can be seen that the composition exhibits a sufficiently higher shear shear load value than that of the composition using the branched PPS resin having a specific ratio.

Example 6, Comparative Example 6 A test piece was injection molded from the composition in the proportions shown in Table 6 below, and a shear fracture test on the collar portion was performed.

The test piece was kneaded by the same method using the same material as in Example 3 and was molded by injection molding into a cylindrical shape with a single-sided flange.
Test piece shape is 9mm outer diameter, 6mm inner diameter, length (including the collar)
The outer diameter was 6 mm, the outer diameter of the collar was 12 mm, and the thickness of the collar was 1.5 mm.

Each test piece was fixed to the push-pull stand (H-12 type) described in Example 4 so that the collar surface was on the upper side, and the sleeve portion was made of an aluminum sleeve having an outer diameter of 12 mm, an inner diameter of 10 mm, and a length of 5 mm. Then, the collar was subjected to a shear fracture test so that the load was uniformly applied around the collar of the test piece. The test conditions were a deformation rate of 8 mm / min and a temperature of 25 ° C., and the load at the time of shear failure of the flange portion of the test piece was measured. The measurement results are shown in Table 6 above.
Also described in.

From the comparison between Example 6-A and Comparative Example 6-A, and Example 6-B and Comparative Example 6-A, it was found that the composition using the linear PPS had higher collar shear fracture strength in the same composition. Indicates
Moreover, in the composition using linear PPS, [matrix /
Even if the ratio of the filler (PTFE resin powder + oxybenzoyl polyester resin powder)] is reduced, the brim is still sufficiently higher than the composition using the branched PPS resin having a [matrix / filler] ratio of 1.5 times larger. It can be seen that the partial shear fracture load value is shown. This result is exactly the same as the result of Example 5 described above.

As described above, in any of Examples 4 to 6, the linear PPS resin composition of the present invention was carried out on the assumption that the mechanical properties of the linear PPS resin composition can be kept equal to or higher than those of the branched PPS resin composition. As shown in Examples 1 to 3, it has been confirmed that the composition of the present invention having excellent friction and wear characteristics can be provided.

(Effects of the Invention) The polyphenylene sulfide resin composition of the present invention is a fluororesin for improving friction characteristics and an oxybenzoyl polyester for improving abrasion characteristics by using a linear polyphenylene sulfide resin as a base resin. With the branched PPS resin, it is now possible to add evenly large amounts, which is unthinkable, so the friction and wear characteristics are significantly improved. In addition, since the standard linear polyphenylene sulfide resin is rich in toughness, even if a large amount of fluororesin or oxybenzoyl polyester is added, the mechanical properties are not significantly deteriorated, and excellent friction and wear characteristics, It has become possible to manufacture strong sliding members that also have mechanical properties.

[Brief description of drawings]

The figure is a diagram in which the results of the wear test shown in Example 1 and Comparative Example 1 are plotted.

Continuation of front page (56) Reference JP 61-266451 (JP, A) JP 57-167348 (JP, A) JP 57-105442 (JP, A) JP 60-127933 (JP , A) JP-A-57-51739 (JP, A) JP-A-58-160626 (JP, A) JP-A-62-549 (JP, A)

Claims (1)

[Claims] 1. A linear polyphenylene sulfide resin 30.
A polyphenylene sulfide resin composition consisting of ˜85 wt%, oxybenzoyl polyester 5˜30 wt% and fluororesin 10˜60 wt%, wherein the linear polyphenylene sulfide resin is 310 ° C. and the shear rate is 200 (seconds). ^A polyphenylene sulfide resin composition having a melt viscosity of 1,000 poise or more measured by ^-1 .