JPH0335032A - Production of vulcanized molded body of fluorine-containing elastomer having modified surface - Google Patents

Abstract

PURPOSE:To impart excellent nontackiness and low frictional properties in a short time and stably suppress increase in hardness and deterioration in tensile physical properties for a long period by impregnating a vulcanizable molded body with a polyhydroxy compound and specific compound from the surface thereof and then vulcanizing the resultant impregnated molded body. CONSTITUTION:A fluorine-containing elastomer vulcanizable molded body is impregnated with (A) a polyhydroxy compound and (B) at least one selected from organo-quaternary ammonium hydroxides, organophosphonium hydroxides and bis(organophosphine)iminium hydroxides from the surface thereof and then vulcanized. The fluorine-containing elastomer may be an elastomer vulcanizable with the polyhydroxy compound and, e.g. vinylidene fluoride-hexafluoropropylene copolymer, etc., are used.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a novel method for producing a surface-modified fluorine-containing elastomer vulcanized product. In more detail,
The present invention relates to a method for producing a fluorine-containing elastomer vulcanized molded article, which has a vulcanized density that gradually decreases from the surface toward the inside, and exhibits stable non-adhesion and low friction properties over a long period of time.

BACKGROUND ART Conventionally, fluorine-containing elastomer vulcanized products have been widely used, for example, in fields such as automobiles, industrial machinery, and chemical plants. When this fluorine-containing elastomer vulcanized product is used for parts that come into contact with other objects, such as automobile intake and exhaust systems, fuel system control valves, other mechanical pulps, O-rings, gaskets, cables, and copying machine fixing rolls, It is necessary that the surface be non-stick.

So far, methods for modifying the surface of such rubber elastic bodies include methods using fluorine gas or secondary amines, or treatment with metallic sodium in liquid ammonia to make the surface non-adhesive and low-friction. A method is known (Japanese Unexamined Patent Publication No. 61-247744).

However, in the former method, the surface of the molded mass often hardens and its properties as a rubber are impaired, and in the latter method, highly dangerous liquid ammonia and metallic sodium are used. Above, -70~-
Since it is necessary to work in an ultra-low temperature atmosphere of 35° C., it is not practical in terms of equipment and handling.

On the other hand, known physical surface treatment methods include, for example, a seven-layer resin coating method, a high-energy etching method, and a deposit method.

However, among these methods, neither the high-energy etching method nor the deposit method has yet achieved sufficiently satisfactory results in terms of non-adhesive surfaces and low friction properties. In addition, in the fluororesin coating method, although non-adhesiveness and low friction can be achieved to some extent, the resulting treated surface may deteriorate if used for a long period of time.
Not only does this have the disadvantage of causing peeling, but it also inevitably increases processing costs.

On the other hand, there is a method of impregnating the surface of a fluorine-containing elastomer vulcanized body with a polyhydroxy compound and a vulcanization accelerator used as desired, and then vulcanizing it again to modify the surface of the body. It has been proposed (Japanese Unexamined Patent Publication No. 63-29
Publication No. 1930). This method can be said to be a preferable method because it can achieve non-adhesion and low friction to some extent without impairing rubber elasticity. However, recently there has been an increasing demand for fluorine-containing elastomer molded products that exhibit excellent non-stick properties even under more extreme usage conditions, and in order to meet these demands, this method
It is necessary to perform the impregnation treatment under more extreme conditions, but in this case, new problems arise, such as an increase in hardness and a risk of a decrease in physical properties.

Problems to be Solved by the Invention The present invention improves the drawbacks of such conventional methods,
A fluorine-containing material that provides excellent non-adhesion and low friction properties with a shorter immersion treatment, minimizes increases in hardness and decreases in tensile properties, and maintains these properties stably over a long period of time. This was made for the purpose of providing an elastomer vulcanized molded product.

Means for Solving the Problems The present inventor has conducted intensive research to develop a surface-modified fluorine-containing elastomer vulcanized product having the above-mentioned preferable properties, and as a result, from the surface of the fluorine-containing elastomer vulcanized product, It was discovered that the object could be achieved by impregnating a polyhydroxy compound with a specific compound and then vulcanizing it, and based on this knowledge, the present invention was developed.

That is, the present invention provides a method for detecting the inside of (A) a polyhydroxy compound and (B) organo quaternary ammonium hydroxide, organophosphonium hydroxide, and bis(organophosphine) iminium hydroxide from the surface of a fluorine-containing elastomer vulcanized product. The present invention provides a method for producing a surface-modified fluorine-containing elastomer vulcanized product, which comprises impregnating it with at least one selected from the following and vulcanizing it.

The present invention will be explained in detail below.

The fluorine-containing elastomer vulcanized product used in the method of the present invention is prepared by blending a vulcanizing agent and a vulcanization accelerator with a fluorine-containing elastomer, and optionally a vulcanization accelerator and activator.
It is vulcanized and molded with carbon black, metal oxides, metal hydroxides, anti-aging agents, lubricants, etc.
- It may be a secondary vulcanized molded product or a second vulcanized molded product. Further, the fluorine-containing elastomer is not particularly limited as long as it can be polyhydroxy vulcanized. Examples of such fluorine-containing elastomers include vinylidene fluoride-propylene hexafluoride copolymer, vinylidene fluoride-propylene hexafluoride copolymer, and vinylidene fluoride-propylene hexafluoride-tetrafluoroethylene terpolymer. and bromine- or iodine-containing copolymers thereof. These fluorine-containing elastomers may be used alone or in combination of two or more.

The main vulcanization methods for the fluorine-containing elastomer include polyhydroxy vulcanization, diamine vulcanization, and peroxide vulcanization. Agents, vulcanization aids, etc. differ depending on the vulcanization method. For example, in the polyhydroxy vulcanization method, polyhydroxy compounds such as bisphenol AF, bisphenol A, and hydroquinone are used as the vulcanizing agent. Further, as the vulcanization accelerator, organo-quaternary ammonium halide, organophosphonium halide, bis[organophosphine]iminium halide, etc. are used, and typical examples thereof include 8-benzyl-1,8-diaza- Bicyclo(5,4,0)-7-
Examples include unzocenium chloride (DBUB'C), benzyltriphenylphosphonium chloride (BTPPC), bis(benzyldiphenylphosphine)iminium chloride (BDP rc), and the like.

Furthermore, sulfones and sulfoxides are used as vulcanization accelerating activators that may be added as necessary, and representative examples include dimethylsulfone, 4,4'-dichlorodiphenylsulfone, and dimethylsulfoxide. It will be done.

Further, in the diamine vulcanization method, as a vulcanizing agent, for example, N,N'-dicinnamylidene-1,6-hexanediamine, triethylenetetramine, ethylenediamine carbamate, etc. are used. On the other hand, examples of the vulcanizing agent in the peroxide vulcanization method include dicumyl peroxide, 2,5-dimethyl-2,5-di(1-butylperoxy)hexane, and benzoyl peroxide. It is usually used in combination with a heptanomer such as triallylisocyanurate, polyfunctional methacrylate, and N,N'-m-phenylene dimaleimide.

In addition, there are no particular restrictions on carbon black that can be added as necessary, but generally MTlSRF, FEF%
Carbon such as FT is used. Furthermore, examples of metal oxides include magnesium oxide, calcium oxide,
Lead oxide or the like is used, and examples of the metal hydroxide include calcium hydroxide and magnesium hydroxide.

Furthermore, the lubricant that can be added as needed is easily microdispersed in the fluorine-containing elastomer compound.
There is no particular restriction as long as it does not repel the treatment liquid during the surface treatment described below.

In the method of the present invention, from the surface of the fluorine-containing elastomer vulcanized rod, the vulcanizing agent (A) polyhydroxy compound and the vulcanization accelerator (B) organoquaternary ammonium hydroxide, organophosphonium hydroxide, and bis(organophosphine)iminium hydroxide, and then impregnated with at least one selected from the group consisting of
Vulcanization treatment is applied. Examples of the polyhydroxy compound of the processing agent component (A) include bisphenol AF.

Examples include bisphenol A1 hydroquinone, and these may be used alone or in combination of two or more.

In addition, examples of the organo-quaternary ammonium hydroxide of the treatment agent component (CB) include tetramethylammonium hydroxide, triethylbenzylammonium hydroxide, 8-benzyl-1,8-diaza-bicyclo(5,4,0)- 7-unzocenium hydroxide (
Examples of organophosphonium hydroxides include triph2nylethylphosphonium hydroxide, benzyltriphenylphosphonium hydroxide (BTPPH), and bis(organophosphine)iminium hydroxides. Examples include bis(triphenylphosphine)iminium hydroxide and bis(benzyldiphenylphosphine).These (B) treatment agent components may be used in 111, or two or more types may be used in combination; ) It may substantially form a salt with the polyhydroxy compound of the processing agent component, or it may be in a dissociated state.

Next, to explain one example of a preferred embodiment of the present invention, first, (A) a polyhydroxy compound as a treatment agent component, (B) a treatment agent component and a vulcanization accelerator such as dimethyl sulfone used as necessary. After dipping the fluorine-containing elastomer-added VT molded product into a treatment solution prepared by dissolving an activator in a suitable organic solvent and impregnating the surface with these agents,
Remove and dry.

Regarding the organic solvent used in the treatment liquid, it dissolves (A) the polyhydroxy compound of the treatment agent component and (B) the treatment agent component, and swells the fluorine-containing elastomer vulcanized molded product, and also allows the treatment liquid to be used during removal. There is no particular restriction as long as it does not flick. Preferred solvents include, for example, acetone, methyl ethyl ketone, methanol, and ethanol, and these may be used alone or in combination of two or more.

The treatment agent component (B) can be obtained by, for example, dissolving the halide type vulcanization accelerator mentioned above in an organic solvent and passing this solution through a strongly basic ion exchange resin column, or adding sodium to the solution. It can be obtained in the form of an organic solvent solution by adding an organic solvent solution containing alcolade, potassium alcolade, sodium hydroxide, potassium hydroxide, etc. and removing the precipitated sodium halide and potassium halide by means such as filtration. can. Therefore, a treatment liquid can be prepared by dissolving the polyhydroxy compound (A) as a treatment agent component in this. When preparing this surface treatment liquid, there is no problem even if it contains some water.

The concentrations of (A) the polyhydroxy compound of the treatment agent component and (B) the treatment agent component in the treatment liquid are determined in order to increase the vulcanization density of the surface layer and to increase the non-adhesion and low friction properties. , it is better to increase its concentration. Further, the temperature and time of immersion are appropriately selected depending on the swelling property and concentration of the solvent, but if the immersion time is not long, the vulcanization density increases to the inside, which impairs the rubber elasticity, which is not preferable. Therefore, a high concentration and short time impregnation treatment is desirable.

Specifically, the concentration of the polyhydroxy compound (A) as the treatment agent component in the treatment solution is usually 1 to 50% by weight, and the concentration of the treatment agent component (B) is usually selected in the range of 0.1 to 20% by weight. The immersion temperature is preferably in the range of 0-180°C, and the immersion time is short if the fluorine-containing elastomer has a low fluorine content because the swelling speed is fast, but if the fluorine content is high, the immersion time is the opposite. Since the swelling speed is slow, it is desirable to soak for a long time, usually from 1 minute to 24 minutes.
Selected within a time range. In addition, it is also important to uniformly adhere the treatment agent to the surface during the drying process after immersion in order to provide non-stick properties.

Next, the molded body that has been subjected to the soaking and drying treatment in this manner is subjected to a vulcanization treatment. Although there are no particular restrictions on this vulcanization treatment, the fluorine-containing elastomer, vulcanizing agent, vulcanization accelerator, etc. Depending on the type of material, select the temperature and time appropriately to volatilize and decompose excess vulcanizing agent and vulcanization accelerator,
It is preferable to avoid deterioration of compression set and heat aging characteristics at higher temperatures.

By such a method, a surface-modified fluorine-containing elastomer vulcanized product having a high vulcanization density in the surface layer portion and a vulcanization density that gradually decreases toward the inside can be obtained. If the vulcanization density of the surface layer is too much higher than that of the inside, the surface layer will become too hard and will not elongate, so there is a risk that the performance as an elastomer will not be fully exhibited. Further, it is preferable that the state of decrease in the vulcanized density is continuous; if this state becomes discontinuous, it becomes easy to peel off during long-term use.

There are no particular restrictions on the hardness of the surface-modified fluorine-containing elastomer vulcanized product obtained by the method of the invention, but JIS A
It is desirable that the hardness is in the range of 50 to 95. If the hardness is too low, the non-adhesive properties will be insufficient, and if the hardness is too high, the sealing properties will be poor, there will be no elongation, and the material will become brittle, which is not preferable.

The surface-modified fluoroelastomer vLIR shape that satisfies these conditions has no peeling on the surface layer or cracking during tension, has excellent rubber elasticity, and has low tensile strength, elongation, and compression set. It has extremely excellent non-adhesive properties and low friction properties.

Effects of the Invention According to the method of the present invention, a molded article having excellent non-adhesive properties and low friction properties can be easily obtained without impairing the physical properties inherent to the fluorine-containing elastomer.
This product is suitable for applications that require the above performance, such as control valves, oil seals, diaphragms, gaskets, O-rings, and blade cables, as well as rolls such as fuser rolls for copying machines that require toner offset prevention. is also suitably used.

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

Note that the adhesive strength was measured according to the following method.

That is, a rubber sheet (35x35x2) is pasted on a smooth table with heat-resistant double-sided tape, and a flat ring made of reins (JIS S-45C) with a weight holder and a hanging device is attached to the rubber sheet. Place it in contact with the sheet (the size of the ring is 25 mm in outer diameter and 19 mm in inner diameter, and the surface that will come into contact with the rubber sheet is polished with #1000 abrasive paper). Next, a weight is placed on the weight holder of the ring so that the total load on the rubber sheet is 6099/cm".The whole is placed in an open air at 120°C and left for 20 hours, then taken out and Leave to cool for an hour. When the temperature has dropped to 23°C, remove the weight, attach the ring to the rubber sheet with it stuck to a tensile testing machine containing a load cell using the above-mentioned hanging device, and perform a tensile test at a tensile speed of 50+*i+/win. Measure tensile adhesion.

Examples 1 to 5 After kneading with a 6-inch roll at the compounding ratio shown in Table 1, secondary vulcanization was performed using a hot press under the conditions shown in Table 2 to form a 90 x 160 x 2 mm (7 ) created a sheet.

Next, BDPIH, BTPPH, D with the composition shown in Table 2
First, the surface treatment liquid containing the respective accelerators of BUBH and the vulcanizing agent bisphenol AF was applied to BDPIC and BTPPC.
.

A methanol solution containing an equimolar amount of sodium methylate is poured into each high concentration solution of DBUBG and mixed, the precipitated sodium chloride is filtered and washed, and bisphenol AF is dissolved in the washing solution along with the remaining solvent to obtain a predetermined concentration. It was prepared as a solution of methanol/acetone-1/1 (volume ratio).

The vulcanized sheet was immersed in this treatment solution under the conditions shown in Table 2, air-dried overnight, and further dried at 120° C. for 60 minutes.

Next, secondary vulcanization was performed in an oven under the conditions shown in Table 2, and adhesive strength and other physical properties were determined.

The results are shown in Table 2.

Comparative Examples 1 to 6 Vulcanized sheets were prepared in the same manner as Examples 1 to 5 using the formulations shown in Table 1.

A surface treatment solution containing a vulcanization accelerator for BDPIC, BTPPC, and DBUBC and bisphenol AF as a vulcanizing agent was prepared by dissolving them in methanol/acetone-1/1 (volume ratio) to a predetermined concentration. .

Next, for Comparative Example 1, leave it as is, Comparative Examples 2 to 6
After surface treatment was performed in the same manner as in Examples 1 to 5 under the conditions shown in Table 2, secondary vulcanization was performed.

These results are shown in Table 2.

As is clear from the comparison of Example 112 and Comparative Examples 1 to 3, the comparison of Example 3 and Comparative Example 4, the comparison of Example 4 and Comparative Example 5, and the comparison of Example 5 and Comparative Example 6, vulcanization When using a hydroxide type accelerator, the same level of non-stickiness can be achieved in a shorter immersion time than when using a conventional halide, in this case a chloride type, and the physical properties (tensile strength and elongation) deteriorate less. I know it will happen. Shortening the soaking time will reduce the swelling of the fluororubber product during soaking, and in the case of vulcanized adhesive products with metals, it will also help maintain the adhesive strength.

Claims (1)

[Claims] 1 From the surface of the fluorine-containing elastomer vulcanized product, (A
) a polyhydroxy compound and (B) at least one selected from organo quaternary ammonium hydroxide, organophosphonium hydroxide and bis(organophosphine)iminium hydroxide, and then vulcanization. A method for producing a surface-modified fluorine-containing elastomer vulcanized product.