JPH0129819B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In the area of fluorinated elastomer development, clear demands have become increasingly powerful in recent years.
Namely: - General improvement of the rheological properties and processability (workability) of mix materials for molding - Obtaining low hardness products of 55 IRHO or less - Possibility to easily extrude products with complex external shapes and fairly large dimensions. That's what sex is.

Such objectives have been pursued and achieved using molding aids of the plasticizer type or with various lubricants. However, polyesters, polyethylene,
The products that have been used for this purpose, such as pentaerythritol tetrastearate and waxes, are in each case not suitable, since they significantly weaken the typical properties of fluorinated elastomers. I couldn't say it.

In fact, in order to impart well-known properties such as heat resistance and fluid resistance to this elastomer, 200
An unavoidable condition is to carry out a "thermal stabilization" (post-balcanization) treatment at a temperature range of 250 °C to 250 °C for about 24 hours.

During the above operations, standard plastics (eg, various glycols, stearates, organophosphates, oleic acids, phthalates, etc.) evaporate and decompose or otherwise decompose. As a result of this, the mechanical properties of the final processed product are significantly impaired, in particular: - an excessive increase in hardness - a weakening of the resistance to permanent compression set ("compression strain") - elastic properties (low elongation and high modulus of elasticity values) - This results in low heat resistance that prevents use under harsh usage conditions (high temperatures of 180°C or higher).

To summarize the above, it can be said that the benefits obtained in the processing stage also become unwelcome drawbacks in the final processed product.

In this way, the plasticity used and the amount of lubricant used also vary.
It is used only in a small amount (1 to 3 parts by weight) that does not change the final properties of the vulcanized product, but on the other hand, this amount is insufficient to meet the above requirements. be.

In particular, perfluorosilicone oil is difficult to mix into fluorocarbon rubber, but when used, it is possible to lower the hardness of the product by 4 to 5 points to the minimum limit of 50 IRDH. Are known.

Furthermore, the vulcanization rate decreases, and the compressive strain value and heat resistance deteriorate.

In particular, the use of very low molecular weight fluorinated polymers with a waxy consistency, such as DuPont's Viton LM, to impart improved rheological properties to molecules, especially during extrusion processing. was held. In this way, it becomes possible to obtain an extrusion molded product with large dimensions and a complicated external shape.

However, when such a "plasticizer" is used in an amount of 10 to 20 parts by weight per 100 parts of fluorine rubber, the following problems occur. That is: - This is possible only using conventional vulcanization systems based on polyamines, compared to those based on bisphenols, vulcanization accelerators, etc., mixed into fluorocarbon rubber. unsuitable for modern vulcanization systems - causes slowdown of the vulcanization operation and therefore requires extended residence time in the forming press. However, it has been found that the above-mentioned drawbacks that occur when conventionally known molding aids for fluorine rubber mixes are used can be avoided by using perfluoropolyether polyamides. Such polyamides are derived from aliphatic and aromatic difunctional amines and have the formula -COCF ₂ O (CF ₂ O) _o - (CF ₂ CF ₂ O) _n - CF ₂ -
It has a structure formed by a group of repeating or cyclic units represented by CO-NR-A-NR-.

Note that in the formula, CF ₂ O and CF ₂ CF ₂ O are oxyperfluoroalkylene units, and it has been found that they exist simultaneously and are statistically distributed along the molecular chain. The indicators n and m are both integers from 2 to 100, the sum of n and m is a number in the range from 5 to 200, preferably from 15 to 100, and n to m
The ratio is between 0.2 and 1.5, preferably between 0.3 and 1.2. A has 2 carbon atoms which may have an alkyl substituent having 1 to 6 carbon atoms in the main chain;
to 20, preferably 6 to 12 alkenyl radicals b 5 to 10 carbon atoms optionally carrying an alkyl substituent having 1 to 6 carbon atoms
Cycloalkenyl groups c Heterocyclic groups having a ring with 5 or 6 atoms d O, S atoms or -CO-, -SO-, -NH
-, -SO ₂ -, an organic diarylene group selected from arylene or alkylarylene groups having one or several benzene rings, each of which may be linked by an alkenyl group having 1 to 3 carbon atoms, etc. and R is selected from hydrogen-containing groups or alkyl or phenyl groups.

The above polyamides obtained from perfluorinated ether derivatives are described in detail in Italian Patent No. 956237, filed in the name of the present applicant.

In this patent, difunctional amines are defined by the formula HOOC-CF ₂ O (CF ₂ CF ₂ O) _n - (CF ₂ O) _o -
By mixing and polycondensing polyoxyperfluoroalkanedioic acid of CF ₂ COOH with a certain amount of corresponding monocarboxylic acids containing inert end groups of the type -OCF ₃ , -OCF ₂ Cl, the polyamide of the present invention can be produced. A method for preparing the same is described.

The mixture has a degree of functionality ranging from 1.4 to 1.99.

The above-mentioned fluorinated polyamides are used as processing aids for fluorinated elastomers in an amount of 5 to 15 parts by weight per 100 parts of the elastomer.

The most suitable fluorinated polyamides for this purpose are:
In a mixed solvent of 1,1,2-trichloro-trifluoroethane and dimethylformamide at 20°C using a Deslieux-Bischjotz free fall viscometer.
It has an intrinsic viscosity of 0.1 to 0.6 [-dl/g] as measured in a 0.3% polyamide solution. This intrinsic viscosity is

Claims (1)

[Scope of Claims] 1. Fluorinated elastomer 100, which is based on a copolymer elastomer of vinylidene fluoride and fluorinated or chlorinated fluorinated olefins or fluorinated vinyl ethers, and is used as a molding mix processing aid. Per part by weight, formula - COCF ₂ O (CF ₂ O) _o - (CF ₂ CF ₂ O) _n - CF ₂ CO
-NR-A-NR- [In the formula, the CF ₂ O and CF ₂ CF ₂ O units are present in a statistical distribution along the molecular chain, the indicators n and m are integers from 2 to 100, and the n and m The total is in the range of 5 to 200, the n to m ratio is 0.2 to 1.5, and A is a divalent group selected from alkenyl groups, cycloalkenyl groups, arylene groups, alkylarylene groups, and heterocyclic groups. The group R is selected from hydrogen or a group containing an alkyl or phenyl group, and the fluorinated polyamide represented by this formula has an intrinsic viscosity [dl/g] measured as described in the Detailed Description of the Invention. ] 0.1 to 0.6 ] A vulcanizable composition comprising 5 to 15 parts by weight of a fluorinated polyamide having a structure constituted by repeating units represented by [0.1 to 0.6]. 2 Per 100 parts by weight of fluorinated elastomer, formula Or the formula X―O―(CF ₂ CF ₂ O) _p ―(CF ₂ O) _q ―
Y [wherein, X and Y are perfluoroalkyl groups, n
is an integer from 30 to 100, m is an integer from 1 to 5 p
is an integer between 60 and 1600, q is an integer between 100 and 2700, and the viscosity in the above formula is between 1000 and 2700.
10000c. Stokes, later formula 500 or
30,000 c.Stokes] containing 1 to 7 parts by weight of a mixture of 15 to 40% by weight of polytetrafluoroethylene and 85 to 60% by weight of perfluoropolyether. The vulcanizable composition described in . 3. The vulcanizable composition according to claim 1, comprising a bisphenol type vulcanizing agent and a vulcanization accelerator. 4 Based on a copolymer elastomer of vinylidene fluoride and fluorinated or chlorinated olefins or fluorinated vinyl ethers, as a molding mix processing aid, per 100 parts by weight of the fluorinated elastomer, formula: - COCF ₂ O (CF ₂ O) _o - (CF ₂ CF ₂ O) _n - CF ₂ CO
-NR-A-NR- [In the formula, the CF ₂ O and CF ₂ CF ₂ O units are present in a statistical distribution along the molecular chain, the indicators n and m are integers from 2 to 100, and the n and m The total is in the range of 5 to 200, the n to m ratio is 0.2 to 1.5, and A is a divalent group selected from alkenyl groups, cycloalkenyl groups, arylene groups, alkylarylene groups, and heterocyclic groups. The fluorinated polyamide represented by this formula, in which the group R is selected from a group containing hydrogen, an alkyl group, or a phenyl group, has an intrinsic viscosity [dl/g] measured as described in the "Detailed Description of the Invention". A vulcanized fluorinated elastomer obtained by starting from a vulcanizable composition comprising 5 to 15 parts by weight of a fluorinated polyamide having a structure constituted by repeating units having 0.1 to 0.6]. Molded product used as a base. 5 The vulcanizable composition is a fluorinated elastomer 100
Per part weight formula Or the formula X―O―(CF ₂ CF ₂ O) _p ―(CF ₂ O) _q ―
Y [wherein, X and Y are perfluoroalkyl groups, n
is an integer from 30 to 100, m is an integer p from 1 to 5
is an integer between 60 and 1600, q is an integer between 100 and 2700, and the viscosity in the above formula is between 1000 and 2700.
10000c. Stokes, later formula 500 or
30,000 c. A molded product based on the vulcanized fluorinated elastomer described in 1.