RU2366671C1 - Oil resistant thermoplastic rubber - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: rubber composition consists of, wt %: polypropylene - 3-21, butadiene-nitrile rubber - 22-55, olefin rubber - 2.5 -9.5, modificator, cross-linking agent for rubbers - 1.5-3.5, activator - 0.18-0.3, plasticiser - 3.0-7.5, mineral oil - 8-40. The composition contains polyisocyanate containing not less than two isocyanate groups (0.05-2.3 wt %) as a modificator and polypropylene with 1-6% of grafted maleic anhydride or maleic acid - 6-20 wt %. Plasticiser solubility parametre of is not less than 18 (kJ/m³)^1/2.

EFFECT: oil resistance enhancing, decrease of relative residual elongation and melt flow index.

1 tbl, 9 ex

Description

The invention relates to thermoplastic rubber (TPR) with increased resistance to hydrocarbon oils, which can be used for the manufacture of various elastic rubber products by extrusion, injection molding and blow molding, such as hoses, seals, gaskets, automobile elastic products, corrugated elastic products , and other elastic products working in contact with petroleum products.

Known oil-resistant thermoplastic rubber, consisting of crystalline polyolefin, polar rubber, filler and vulcanizing agent (US Pat. RF 2138522, IPC ⁵ C08L 23/12 from 10.07.97).

This TPR has a high relative residual elongation after rupture (140-180% after rupture) and a low melt flow rate (0.02-0.8 g / 10 min at 190 ° C and a load of 10 kg).

Known oil-resistant thermoplastic rubber consisting of polypropylene, nitrile butadiene rubber, a vulcanizing agent and a modifier, which is a grafted copolymer of polypropylene and nitrile butadiene rubber (US Pat. US 4355139, IPC C08F 8/00).

This TPR has an unsatisfactory high relative residual elongation after rupture (240-480%) and a low melt flow rate (0.02-0.8 g / 10 min).

The closest in essence and technical level is oil-resistant thermoplastic rubber, consisting of polypropylene, nitrile butadiene rubber, olefin rubber, a vulcanizing agent and a modifier, which is a grafted copolymer of polypropylene and nitrile butadiene rubber with terminal amino groups (US Pat. 9/02).

This TPR has a high relative residual elongation after rupture (190-380%) and oil absorption (19.7-48.2%).

The objective of the invention is to obtain a thermoplastic rubber based on crystalline polyolefin and nitrile rubber, combining low oil absorption (increased oil resistance), low relative elongation and increased melt flow rate.

The technical problem is solved in that the oil-resistant thermoplastic rubber obtained from a composition consisting of polypropylene, nitrile butadiene rubber, olefin rubber, a modifier, a vulcanizing agent for rubbers - alkyl phenol-formaldehyde resin and a vulcanization activator - tin chloride or aluminum chloride, differs as a modifier contains a polyisocyanate containing at least two isocyanate groups, and PP with a content of 1-6% grafted maleic anhydride or maleic acid, and additionally о contains mineral oil and a plasticizer, characterized by a solubility parameter of at least 18 (kJ / m ³ ) ^1/2 , with the following ratio of components (wt.%):

polypropylene 3-21 nitrile butadiene rubber 22-55 olefin rubber 2.5-9.5 polyisocyanate containing at least two isocyanate groups 0.05-2.3 polypropylene with a content of 1-6% grafted maleic anhydride or maleic acid 6-20 mineral oil 8-40 specified plasticizer 3-7.5 specified curing agent 1,5-3,7 vulcanization activator 0.18-0.35,

which allows to obtain a TPR with low oil absorption (7.4-18.6%) and residual elongation (49-93%).

Table 1 shows the compositions, and in table 2 the characteristics of the proposed TPR.

Substances used

As polypropylene, polypropylene or a copolymer of propylene and ethylene with an ethylene content of 2-8%, for example polypropylene according to TU 2211-3136-05766801-2006 (Plastics. Properties and applications. Reference book. // Katsnelson M.Yu., Balaev G .A. L.: Chemistry, 1978, 382 p.).

As a nitrile butadiene rubber, a statistical copolymer of butadiene and acrylic acid nitrile with an acryl acid nitrile content of 18 to 42 wt.% Can be used (Handbook of rubber worker. Materials of rubber production. / P.I. Zakharchenko et al. M .: Chemistry, 1971, 606 p.).

As the olefin rubber obtained by copolymerization of olefins and diene, a copolymer of ethylene with propylene and dicyclopentadiene, a copolymer of ethylene with propylene and ethylidene norbornene, for example, SKEPT brand (TU 2294-022-05766801-2002), an isobutene copolymer, can be used isobutylene with butadiene, for example butyl rubber (BK) (TU 2294-021-48158319-2001) (Handbook of rubber worker. Materials of rubber production. / P.I. Zakharchenko et al. M .: Chemistry, 1971, 606 p.).

As the polyisocyanate, any aliphatic or aromatic polyisocyanate containing at least two isocyanate groups in one molecule can be used, for example phenylenediisocyanate (PDI), toluene diisocyanate (TDI), hexamethylene diisocyanate (HMDI), diphenylmethanediisocyanate (MDI) trimers of the listed isocyanates, mixtures of the listed isocyanates of their dimers and trimers (Gorbatenko V.I., Zhuravlev E.Z., Samorai L.I. Isocyanates. Synthesis methods and physicochemical properties of alkyl, aryl and ge eril isocyanates Handbook Kiev:.. Naukova dumka, 1987, 448)..

As PP grafted with maleic anhydride or maleic acid, any PP containing 1.0-6.0% grafted maleic anhydride or maleic acid, for example Polybond 3000 or Polybond 3200 manufactured by Chemtura Corporation, can be used. PP with grafted maleic anhydride or maleic acid is obtained by mixing the appropriate amounts of PP with maleic acid or maleic anhydride in the presence of organic peroxide at a temperature above the melting point of PP, for example, according to the method described in US Pat. USA 3483276, 1969

As the oil, paraffin, naphthenic or aromatic hydrocarbon oil of mineral origin can be used, used as a softener or plasticizer in rubbers, for example, PM grade (TU 38.401172-90), MP-75 grade (TU 38.101952-83), Stabiloil-18 brand (TU 38.101367-78) and others. (Handbook of rubber worker. Materials of rubber production. / P.I. Zakharchenko and others. M .: Chemistry, 1971, 606 p.).

Any plasticizer with a solubility parameter (δ) of at least 18 (kJ / m ³ ) ^1/2 (9 (kcal / m ³ ) ^1/2 ) can be used as a plasticizer (Handbook of Physical Chemistry of Polymers. Volume 1. Kiev : Naukova Dumka, 1984, p. 188), e.g. dibutyl phthalate (δ = 19.75 (kJ / m ³ ) ^1/2 ), dihexyl phthalate (δ = 19.11 (kJ / m ³ ) ^1/2 ), dimethyl phthalate ( δ = 22.05 (kJ / m ³ ) ^1/2 ), diethyl phthalate (δ = 20.9 (kJ / m ³ ) ^1/2 ), tributyl phosphate (δ = 18.1 (kJ / m ³ ) ^1/2 ), tricresyl phosphate (δ = 20.37 (kJ / m ³ ) ^1/2 ), tritolyl phosphate (δ = 20.58 (kJ / m ³ ) ^1/2 ), triphenyl phosphate (δ = 21.84 (kJ / m ³ ) ^1/2), trichloroethyl (δ = 22,9 (kJ / ^{m3) 1/2),} triethyl phosphate (δ = 20,25 (kJ / ^{m3) 1/2).}

Any alkyl phenol formaldehyde resin (AFPS) with vulcanization activators, for example, n-tert-butyl phenol formaldehyde resin, n-tert-octyl phenol formaldehyde resin, is used as a vulcanizing agent (Rubber Handbook. Rubber Production Materials. / P.I. Zakharchenko and others. M .: Chemistry 1971. 606 p .; G.A. Bloch Organic rubber vulcanization accelerators (L. Chemistry, 1972). As activators of vulcanization, tin chloride or aluminum chloride is used (Schwartz A.G., Dinzburg B.N. Combining rubbers with plastics and synthetic resins. M: Chemistry, 1972, p. 158).

In addition, well-known additives commonly used for such polymeric materials, such as fillers, antioxidants, lubricants that improve processability into products, and anti-azonates, can be included in the composition.

The invention is illustrated by the following examples of specific performance.

Example 1. In a Brabender mixer at a temperature of 180 ° C for 7 min, 21% of Balen 01030 grade PP, 35.5% of nitrile butadiene rubber grade BNKS-40, 7% of grade Polybond 3200 grade 1 containing PP are mixed , 2% grafted maleic anhydride, 3.5% olefin rubber, grade CEPT, 0.85% toluene diisocyanate, 24.5% mineral oil, grade PM, 4.94% plasticizer, tricresyl phosphate. Then, 2.48% butylphenol-formaldehyde resin and 0.23% tin dichloride dichloride are added to the mixer and mixing is continued for 4 minutes to effect the curing process of the elastomer. It turns out thermoplastic rubber (TPR), which is subjected to tests. The properties of the TPR are shown in table 2.

Methods of testing samples. Deformation-strength properties TPD (Tensile strength - σ _y, the elongation at break - ε, relative residual elongation after fracture - ε _ost) was determined according to GOST 270-75. The melt flow rate (MFR) was determined according to GOST 11645-73 with a load of 10 kg and a temperature of 190 ° C. Oil resistance (oil absorption - α) was determined according to GOST 9.030-74 at 23 ° C by swelling for 168 hours in oil SZHR-1. Shore A hardness was determined according to GOST 263-75 over a period of 5 s.

Examples 2-7. Perform in the same order and under the same modes as example 1. Examples differ only in composition. The composition and properties of thermoplastic rubber compounds are given in tables 1 and 2.

Examples 8, 9 (prototype). Perform in the same order and under the same modes as example 1. Examples differ only in composition. The composition and properties of thermoplastic rubber compounds are given in tables 1 and 2.

As can be seen from the data in table 2, the claimed TPR has lower values of the relative residual elongation after rupture (ε _ost = 49-93%), weaker swells in oil (α = 8.5-18.6%), it has a high melt flow rate ( 2.3-7.2 g / 10 min) than the TPR of the prototype (ε _ost = 190-320%, α = 21.2-26.7%, PTR = 0.3-1.9 g / 10 min )

Increased relative residual elongation of the material according to the prototype leads to the fact that the product from it after deformation does not restore its original dimensions to the right extent and remains largely deformed. This does not allow the use of materials with high relative residual elongation for the manufacture of rubber products. It’s not even important that the absolute value of the relative residual elongation is more important, the value that characterizes how many times the material is compressed after it breaks under tension, determined by the ratio ε _p / ε _rest , is more important. The greater this ratio, the more fully the product recovers its shape after deformation. As follows from table 2, the materials according to the proposed recipe are several times better at restoring their dimensions after deformation (ε _p / ε _ost = 5.2-9.1) than the materials according to the prototype (ε _p / ε _ost = 1.91- 2.47).

In addition, the TPR according to the proposed composition have a higher oil resistance, since they swell to a lesser extent in oil (table 2). This expands the scope of the proposed thermoplastic rubber.

It is important to note that the proposed TPR have a higher melt flow rate (MFR), which expands the number of methods for their processing into products and facilitates this processing. Materials with a low MFI (less than 2 g / 10 min) cannot be processed by injection molding.

Thus, the thermoplastic rubber according to the proposed formulation has a reduced residual elongation, less swelling in the oil and a higher melt flow rate than the thermoplastic rubber of the prototype.

table 2 Properties of Oil Resistant Thermoplastic Rubber No. ε _ost ,% PTR, g / 10min α,% N, conv. σ _y , MPa ε _p ,% ε _p / ε _ost one 2 3 four 5 6 7 8 one 83 6.9 8.5 85 15,2 430 5.2 2 93 7.2 18.6 64 9.3 520 5,6 3 84 5.8 11,2 70 10.8 510 6.1 four 69 3.8 9.1 76 12.7 500 7.2 5 62 3.6 10.3 72 11.5 480 7.8 6 54 2,3 7.4 88 16,2 410 7.6 7 49 3.2 16,2 60 8.3 450 9.1 Prototype Samples 8 190 0.3 26.7 91 15.9 470 2.47 9 320 1.9 21,2 96 24.5 610 1.91 δ _ost - relative residual elongation after fracture, α - oil absorption, MFR - melt flow index, H - hardness Shore A, σ _y - Tensile strength, δ _p - elongation at break.

Claims (1)

Oil-resistant thermoplastic rubber obtained from a composition consisting of polypropylene, nitrile butadiene rubber, olefin rubber, a modifier, a vulcanizing agent for rubbers - an alkyl phenol formaldehyde resin and a vulcanization activator - tin chloride or aluminum chloride, characterized in that it contains a modifier containing at least two isocyanate groups, and polypropylene containing 1-6% grafted maleic anhydride or maleic acid and additionally contains mineral th oil and plasticizer, characterized by a solubility parameter of at least 18 (kJ / m ³ ) ^1/2 , with the following ratio of components (wt.%):
polypropylene 3-21 nitrile butadiene rubber 22-55 olefin rubber 2.5-9.5 polyisocyanate containing at least two isocyanate groups 0.05-2.3 polypropylene with a content of 1-6% grafted maleic anhydride or maleic acid 6-20 mineral oil 8-40 specified plasticizer 3.0-7.5 specified curing agent 1,5-3,7 vulcanization activator 0.18-0.35