CN111171408A

CN111171408A - Low-content polycyclic aromatic hydrocarbon rubber compound and preparation method thereof

Info

Publication number: CN111171408A
Application number: CN202010092357.2A
Authority: CN
Inventors: 许茂祥
Original assignee: Changxin Rubber Industry Shanghai Co ltd
Current assignee: Changxin Rubber Industry Shanghai Co ltd
Priority date: 2020-02-14
Filing date: 2020-02-14
Publication date: 2020-05-19
Anticipated expiration: 2040-02-14
Also published as: CN111171408B

Abstract

The invention relates to the technical field of rubber application, in particular to a low-content polycyclic aromatic hydrocarbon rubber compound and a preparation method thereof. In the rubber compound, the content of benzo (a) pyrene is less than 0.1mg/kg, and the content of benzo (e) pyrene is less than 0.1 mg/kg. The applicant provides a rubber compound, which can reduce the content of polycyclic aromatic hydrocarbon in the rubber compound and ensure safety by selecting proper preparation raw materials, and can be used for materials which are directly or indirectly contacted with a human body, such as toys, tableware, office supplies and the like; in addition, the applicant can effectively relieve the reduction of tensile strength, elasticity and flexing resistance caused by using an effective sulfur vulcanization system by selecting proper preparation raw materials, thereby improving the overall performance and the use stability of the rubber compound.

Description

Low-content polycyclic aromatic hydrocarbon rubber compound and preparation method thereof

Technical Field

The invention relates to the technical field of rubber application, in particular to a low-content polycyclic aromatic hydrocarbon rubber compound and a preparation method thereof.

Background

Polycyclic Aromatic Hydrocarbons (PAHs) are hydrocarbons formed by bonding two or more benzene rings, and are harmful substances generated from fuels such as petroleum and coal, and wood and combustible gases under incomplete combustion or high-temperature treatment conditions. It is commonly present in petrochemicals, rubber, plastics, lubricating oil, rust preventive oil, incompletely combusted organic compounds, and is one of the important carcinogenic substances in the environment. In addition, human activities such as automobile exhaust gas, residential heating systems, waste combustion, hot cracking of petroleum, factory boiler combustion emissions, etc. are also major sources of PAHs.

The rubber is widely applied in production and life of people, for example, tableware, office supplies, toys and the like are frequently contacted with the skin or oral cavity of a human body, if too many PAHs exist in the rubber, the health of the human body is easily damaged, and detailed requirements are made on the PAHs in GS certification of German product safety Committee (AfPS), wherein the maximum total content of polycyclic aromatic hydrocarbons of 1 type of materials (the contact time is more than 30s) of materials which are put in the mouth or materials which are contacted with the skin on the toys is limited to 1mg/kg, and the maximum content of benzo (a) pyrene is limited to 0.2 mg/kg. The preparation of rubber mixtures with a low polycyclic aromatic hydrocarbon content is therefore currently of importance.

Disclosure of Invention

In order to solve the above problems, the first aspect of the present invention provides a low-content polycyclic aromatic hydrocarbon rubber composition containing benzo (a) pyrene in an amount of less than 0.1mg/kg and benzo (e) pyrene in an amount of less than 0.1 mg/kg.

According to a preferable technical scheme, the preparation raw materials of the rubber compound comprise, by weight, 90-120 parts of nitrile rubber, 55-75 parts of filler, 8-13 parts of plasticizer, 0.1-0.8 part of sulfur, 2-5 parts of vulcanization accelerator, 0.1-2 parts of softener and 0.1-2 parts of anti-aging agent.

As a preferable technical scheme of the invention, the Mooney viscosity ML1+4 of the nitrile rubber at 100 ℃ is 40-50, and the content of acrylonitrile is 25-30 wt%.

In a preferred embodiment of the present invention, the filler is one or more selected from carbon black, talc, kaolin, zinc oxide, graphene, white carbon black, kaolin, calcium carbonate, graphite, sericite powder, and illite.

As a preferable technical scheme of the invention, the filler comprises carbon black and zinc oxide, and the weight ratio is (10-15): 1.

as a preferable technical scheme of the invention, the average particle size of the carbon black is 40-60 nm, and the specific surface area is 34-55 m²/g。

As a preferable technical scheme of the invention, the plasticizer comprises short-chain saturated fatty acid ester and long-chain saturated fatty acid ester, and the weight ratio of the short-chain saturated fatty acid ester to the long-chain saturated fatty acid ester is 1: (0.01-0.1).

In a preferred embodiment of the present invention, the vulcanization accelerator is one or more selected from the group consisting of sulfonamide vulcanization accelerators, thiuram vulcanization accelerators, guanidine vulcanization accelerators, dithiocarbamate vulcanization accelerators and thiazole vulcanization accelerators.

In a preferred embodiment of the present invention, the softening agent is one or more selected from mineral oil, animal and vegetable oil, and fatty acid.

In a second aspect, the present invention provides a method for preparing a low polycyclic aromatic hydrocarbon compound as described above, comprising the steps of:

premixing: mixing the nitrile rubber, the filler, the plasticizer and the anti-aging agent to obtain a premix;

mixing: adding sulfur, a vulcanization accelerator and a softening agent into the premix, mixing and vulcanizing to obtain the rubber compound.

Compared with the prior art, the invention has the following beneficial effects: the applicant provides a rubber compound, which can reduce the content of polycyclic aromatic hydrocarbon in the rubber compound and ensure safety by selecting proper preparation raw materials, and can be used for materials which are directly or indirectly contacted with a human body, such as toys, tableware, office supplies and the like; in addition, the applicant can effectively relieve the reduction of tensile strength, elasticity and flexing resistance caused by using an effective sulfur vulcanization system by selecting proper preparation raw materials, thereby improving the overall performance and the use stability of the rubber compound.

Detailed Description

The disclosure may be understood more readily by reference to the following detailed description of preferred embodiments of the invention and the examples included therein. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control.

The term "prepared from …" as used herein is synonymous with "comprising". The terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

The conjunction "consisting of …" excludes any unspecified elements, steps or components. If used in a claim, the phrase is intended to claim as closed, meaning that it does not contain materials other than those described, except for the conventional impurities associated therewith. When the phrase "consisting of …" appears in a clause of the subject matter of the claims rather than immediately after the subject matter, it defines only the elements described in the clause; other elements are not excluded from the claims as a whole.

When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or as a range of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4", "1 to 3", "1 to 2 and 4 to 5", "1 to 3 and 5", and the like. When a range of values is described herein, unless otherwise stated, the range is intended to include the endpoints thereof and all integers and fractions within the range.

The singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. "optional" or "any" means that the subsequently described event or events may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

Approximating language, as used herein throughout the specification and claims, is intended to modify a quantity, such that the invention is not limited to the specific quantity, but includes portions that are literally received for modification without substantial change in the basic function to which the invention is related. Accordingly, the use of "about" to modify a numerical value means that the invention is not limited to the precise value. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value. In the present description and claims, range limitations may be combined and/or interchanged, including all sub-ranges contained therein if not otherwise stated.

In addition, the indefinite articles "a" and "an" preceding an element or component of the invention are not intended to limit the number requirement (i.e., the number of occurrences) of the element or component. Thus, "a" or "an" should be read to include one or at least one, and the singular form of an element or component also includes the plural unless the stated number clearly indicates that the singular form is intended.

The present invention is illustrated by the following specific embodiments, but is not limited to the specific examples given below.

The invention provides a polycyclic aromatic hydrocarbon compound with low content, wherein the content of benzo (a) pyrene in the compound is less than 0.1mg/kg, and the content of benzo (e) pyrene in the compound is less than 0.1 mg/kg.

In a preferred embodiment, the raw materials for preparing the rubber compound comprise, by weight, 90-120 parts of nitrile rubber, 55-75 parts of filler, 8-13 parts of plasticizer, 0.1-0.8 part of sulfur, 2-5 parts of vulcanization accelerator, 0.1-2 parts of softener and 0.1-2 parts of anti-aging agent.

In a preferred embodiment, the raw materials for preparing the rubber compound of the present invention comprise, by weight, 100 parts of nitrile rubber, 65 parts of filler, 10.5 parts of plasticizer, 0.6 part of sulfur, 3 parts of vulcanization accelerator, 1 part of softener and 1 part of antioxidant.

Sulfur

Sulfur is also called sulfur, colloidal sulfur, sulfur block. The appearance is light yellow brittle crystal or powder, and has special odor. The molecular weight was 32.06, the vapor pressure was 0.13kPa, the flash point was 207 ℃, the melting point was 118 ℃, the boiling point was 444.6 ℃, and the relative density (water ═ 1) was 2.0. Sulfur is insoluble in water, slightly soluble in ethanol and ether, and easily soluble in carbon disulfide. Sulfur is widely used in the rubber field as a vulcanizing agent for rubber. The sulfur can be prepared or purchased by self without specific limitation. In a preferred embodiment, the sulfur of the present invention is available from Zhongya chemical Co.

Vulcanization accelerator

Vulcanization accelerators are referred to as accelerators for short. A substance capable of promoting vulcanization. Can shorten the vulcanizing time, reduce the vulcanizing temperature, reduce the consumption of vulcanizing agents, improve the physical and mechanical properties of rubber and the like. The vulcanization accelerator is not particularly limited in the present invention.

In one embodiment, the vulcanization accelerator of the present invention is selected from one or more of sulfonamide vulcanization accelerators, thiuram vulcanization accelerators, guanidine vulcanization accelerators, dithiocarbamate vulcanization accelerators, and thiazole vulcanization accelerators.

As examples of the sulfonamide vulcanization accelerators, there are included, but not limited to, N-t-butyl-2-benzothiazolesulfenamide (TBBS), 2-Mercaptobenzothiazole (MBT), sodium or zinc salt of 2-mercaptobenzothiazole (ZMBT), benzothiazole-2-Dicyclohexylsulfenamide (DCBS), benzothiazole disulfide (MBTS), tetrabenzylthiuram disulfide (TBzTD), N-cyclohexyl-2-benzothiazolesulfenamide (CZ); in a preferred embodiment, the sulfonamide vulcanization accelerator of the present invention is N-cyclohexyl-2-benzothiazolesulfenamide; in a more preferred embodiment, the N-cyclohexyl-2-benzothiazolesulfenamide of the present invention is purchased from Zhengzhou double strength chemical products, Inc.

Examples of the vulcanization accelerators of the thiuram type include, but are not limited to, tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), bis (1, 5-pentamethylene) thiuram tetrasulfide (DPTT); in a preferred embodiment, the thiuram-based vulcanization accelerator of the present invention is tetramethylthiuram disulfide; in a more preferred embodiment, the tetramethylthiuram disulfide of the present invention is available from Zhengzhou double strength chemical products, Inc.

As examples of guanidine vulcanization accelerators, there are included, but not limited to, Diphenylguanidine (DPG), Triphenylguanidine (TPG), diorthotolylene tetralone (DOTG), Orthotolylbiguanide (OTBG), guanidine salts (nitrate, carbonate, acetate, thiocyanate, sulfate), and derivatives thereof.

Examples of the dithiocarbamate vulcanization accelerator include, but are not limited to, zinc dimethyldithiocarbamate (PZ), Zinc Diethyldithiocarbamate (ZDC), zinc dibutyldithiocarbamate (BZ), zinc ethylphenyldithiocarbamate (PX).

Examples of thiazole vulcanization accelerators include, but are not limited to, accelerator M, accelerator DM, accelerator MZ.

Preferably, the vulcanization accelerator comprises a sulfonamide vulcanization accelerator and a thiuram vulcanization accelerator, and the weight ratio is (2-3): (2-3); further, the weight ratio of the sulfonamide vulcanization accelerator to the thiuram vulcanization accelerator is 1: 1.

the applicant finds that by using low-dosage sulfur and high-dosage accelerator as an effective sulfur vulcanization system, the sulfur dosage of the vulcanization system is very small, so that the single-sulfur or double-sulfur cross-linking bond generated in the vulcanized rubber structure accounts for absolute advantages, generally reaches more than 90%, the vulcanization reversion phenomenon does not occur after over-vulcanization, and the obtained vulcanized rubber has excellent heat resistance, compression deformation resistance and aging resistance of the vulcanized rubber and small heat generation. However, compared with the common sulfur vulcanization system with more sulfur, the vulcanized rubber vulcanized by the effective vulcanization system has poor tensile strength, elasticity and fatigue resistance, such as poor yield resistance and flexibility, due to the factors of low content of polysulfide crosslinking bonds and the like.

Filler material

Filler generally refers to a material filled in other objects. In chemical products, the filler is also called filler, which is a solid material for improving processability and mechanical properties of products and/or reducing cost.

In one embodiment, the filler of the present invention is selected from one or more of carbon black, talc, kaolin, zinc oxide, graphene, white carbon, china clay, calcium carbonate, graphite, sericite powder and illite.

Preferably, the filler comprises carbon black and zinc oxide, and the weight ratio is (10-15): 1; further, the weight ratio of the carbon black and the zinc oxide is 12: 1.

carbon black, also known as carbon black, is an amorphous carbon. Light, loose and extremely fine black powder with very large surface area ranging from 10 to 3000m²The carbon-containing substance is a product obtained by incomplete combustion or thermal decomposition of a carbon-containing substance (coal, natural gas, heavy oil, fuel oil, etc.) under the condition of insufficient air. The structural properties of carbon black are expressed by the degree of chain-like or grape-like aggregation among carbon black particles. The higher the carbon black structure, the more easily a space network channel is formed and the less easily it is destroyed. The high-structure carbon black has fine particles, closely packed reticular chains, large specific surface area and more particles per unit mass. The carbon black of the present invention may be purchased or manufactured by oneself; in a preferred embodiment, the carbon black of the present invention is obtained from Cabot's LP series carbon black, such as Spheron SO-LP (average particle size of 40 to 60nm, specific surface area of 34 to 55 m)²(g), Spheron 4000-LP (the average particle diameter is 61-100 nm, and the specific surface area is 20-33 m)²(g), Vulcan 6-LP (average particle diameter of 20-25 nm, specific surface area of 109-123 m)²(iv)/g); in a more preferred embodiment, the carbon black of the present invention is Spheron SO-LP.

The average particle diameter is an average particle diameter of an actual particle group consisting of particles having different sizes and shapes, and is referred to as a spherical particle diameter if the overall lengths of the particle diameters are the same as compared with a hypothetical particle group consisting of uniform spherical particles. Can be tested according to methods well known in the art.

The specific surface area refers to the total area per unit mass of the material. The unit is m²(ii) in terms of/g. Book (I)The specific surface area is measured by the CTAB method.

Zinc oxide is an oxide of zinc. Is insoluble in water and soluble in acid and strong base. Zinc oxide is a commonly used chemical additive, and is widely applied to the manufacture of products such as plastics, silicate products, synthetic rubber, lubricating oil, paint, coating, ointment, adhesive, food, batteries, flame retardant and the like. The invention does not limit the zinc oxide specifically, and can be made by oneself or purchased; in a preferred embodiment, the zinc oxide of the present invention is available from Nks132, national island nacartane new materials technology ltd.

More preferably, the carbon black has an average particle diameter of 40 to 60nm and a specific surface area of 34 to 55m²/g。

The applicant has found that the use of carbon black and zinc oxide as fillers, in particular carbon black and zinc oxide of a certain particle size and specific surface area, is advantageous for increasing the tensile strength, elongation at break and flexibility resistance of the vulcanizate, possibly because the addition of carbon black and zinc oxide can act as a reinforcement, on the one hand, the smaller particle size and the larger specific surface area of carbon black facilitate the contact between carbon black and rubber, increase the physical adsorption between rubber and carbon black, and, on the other hand, because the surface of carbon black contains some active sites with greater activity, which can chemically adsorb rubber, and, on the other hand, by using zinc oxide, it can act as a filler and, together with a softening agent such as stearic acid, promote the crosslinking density, and the combination of the two fillers, forming a physically and chemically crosslinked network with a more suitable density, which, when subjected to tensile forces or repeated flexing, the nitrile rubber molecular chain is easy to slip, and simultaneously, the chemical sites can be utilized to transfer stress, so that brittle fracture is reduced.

However, it should be noted that, compared with the common sulfur vulcanization system mainly having the S-S bond breakage under the action of tensile force, the effective vulcanization system mainly has the C-S bond breakage, and compared with the S-S bond with lower bond energy, the C-S is not easily broken and also not easily generated, so that the force of the broken part cannot be transferred to other chains during repeated flexing, and the reinforcing effect of carbon black and zinc oxide cannot be well embodied.

In addition, applicants have found that when a suitable carbon black, such as the LP series carbon black of cabot, is selected, the compounds prepared have a lower polycyclic aromatic content than conventional carbon blacks, such as ASTM N650, N683, N539, or N550 carbon blacks, and meet the requirements for environmentally friendly products, especially for use in products such as toys that may be included in the mouth, and increased safety. The applicant found that when carbon black having a larger specific surface area or a smaller particle size and zinc oxide are used as fillers, the flex resistance, tensile strength and elasticity are not further increased, which may be caused by the adsorption of too much nitrile rubber around the carbon black.

Softening agent

The softener is an assistant for improving the processing performance and the use performance of rubber, can increase the plasticity of rubber, reduce the viscosity of the rubber and the temperature during mixing, improve the dispersibility and the mixing property, and improve the tensile strength, the elongation and the wear resistance of vulcanized rubber.

In one embodiment, the softener of the present invention is selected from one or more of mineral oil, animal and vegetable oil, and fatty acid.

Examples of the mineral oil include, but are not limited to, paraffinic mineral oil, naphthenic mineral oil, and aromatic mineral oil.

Examples of animal and vegetable oils include, but are not limited to, rapeseed oil, castor oil, cottonseed oil, linseed oil, soybean oil, sesame oil, corn oil, safflower oil, palm oil, coconut oil, peanut oil, wood wax, rosin, pine tar, tall oil.

As examples of fatty acids, including, but not limited to, stearic acid, palmitic acid, lauric acid, lignoceric acid, arachidic acid; in a preferred embodiment, the fatty acid of the present invention is stearic acid; in a more preferred embodiment, the stearic acid of the present invention is purchased from PALMATA 1801 of indolylbox.

Nitrile rubber

The nitrile rubber is prepared from butadiene and acrylonitrile by an emulsion polymerization method, is mainly produced by a low-temperature emulsion polymerization method, and has the advantages of excellent oil resistance, higher wear resistance, better heat resistance and strong bonding force. The disadvantages are poor low temperature resistance, ozone resistance, poor insulation properties and slightly low elasticity. The acrylonitrile-butadiene rubber contains 42-46% acrylonitrile, 36-41% acrylonitrile, 31-35% acrylonitrile, 25-30% acrylonitrile, 18-24% acrylonitrile and the like. The more the acrylonitrile content, the better the oil resistance, but the cold resistance is decreased accordingly. It can be used in 120 deg.C air or 150 deg.C oil for a long period. In addition, it has excellent water resistance, air tightness and excellent adhesion performance. The rubber is widely used for manufacturing various oil-resistant rubber products, various oil-resistant gaskets, sleeves, flexible packages, flexible rubber tubes, printing and dyeing rubber rollers, cable rubber materials and the like, and becomes an indispensable elastic material in the industries of automobiles, aviation, petroleum, copying and the like. The nitrile rubber can be purchased or manufactured by self; in a preferred embodiment, the nitrile rubber according to the invention is selected from one or more of the Perbunan series nitrile rubber, Krynac series nitrile rubber, Baymod series nitrile rubber, Therban series nitrile rubber, langen series nitrile rubber, germany; in a more preferred embodiment, the nitrile rubber of the present invention is a Perbunan series nitrile rubber.

Examples of Perbunan series nitrile rubbers include, but are not limited to, 2255VP, 2845F, 2870F, 2895F, 3430F, 3470F, 3945F, 3965F, 1846F, 4456F; in a more preferred embodiment, the Perbunan series nitrile rubbers according to the present invention are selected from 1846F (mooney viscosity ML1+4 at 100 ℃ is 46, acrylonitrile content is 18 wt%), 2845F (mooney viscosity ML1+4 at 100 ℃ is 45, acrylonitrile content is 28 wt%), 2870F (mooney viscosity ML1+4 at 100 ℃ is 70, acrylonitrile content is 28 wt%), 3945F (mooney viscosity ML1+4 at 100 ℃ is 45, acrylonitrile content is 39 wt%); in a more preferred embodiment, the Perbunan series nitrile rubber of the present invention is 1846F.

Mooney viscosity, also known as rotational (Mooney) viscosity, is a value measured by Mooney viscometer, and can basically reflect the degree of polymerization and molecular weight of synthetic rubber, and rubber materials with high Mooney viscosity are not easy to be uniformly mixed and extruded, and have high molecular weight and wide distribution range. The rubber material with low Mooney viscosity is easy to stick to the roller, and has low molecular weight and narrow distribution range. Too low a Mooney viscosity results in a cured article having low tensile strength. Can be tested according to methods well known in the art, such as ISO289/ASTM D1646.

The acrylonitrile content is the weight percentage of acrylonitrile in the nitrile rubber and can be determined according to methods known in the art, and can be listed as SH/T1157, GB 4486.

In one embodiment, the nitrile rubber of the present invention has a Mooney viscosity ML1+4 at 100 ℃ of 40 to 50 and an acrylonitrile content of 25 to 30 wt%; further, the Mooney viscosity ML1+4 at 100 ℃ of the nitrile rubber of the invention is 45, and the content of acrylonitrile is 28 wt%.

The applicant finds that when the acrylonitrile-butadiene rubber with specific viscosity and acrylonitrile content and the carbon black and the zinc oxide act together, the reinforcing effect of the carbon black and the zinc oxide is further exerted, which is probably because when the acrylonitrile-butadiene rubber with the Mooney viscosity of 40-50, namely with proper molecular weight and fluidity, is used, the uniform dispersion between the acrylonitrile-butadiene rubber and the filler is facilitated, the brittle fracture caused by the uneven dispersion of the filler is reduced, in addition, the molecular weight of acrylonitrile and butadiene monomers in the acrylonitrile-butadiene rubber is controlled, so that the content of carbon-carbon double bonds and nitrile groups in the acrylonitrile-butadiene rubber is controlled, the proper polarity and crosslinking sites are obtained, a uniform chemical crosslinking system can be formed with a vulcanization system, the carbon black and the like, the formation of cavities is reduced, the reinforcement of the carbon black and the zinc oxide is promoted, in addition, the lower content of acrylonitrile is used, the large relaxation time caused by the large intermolecular force of the acrylonitrile-butadiene rubber under stress is, the impact on elasticity and repeated flexing performance, and the acrylonitrile branched chain in the nitrile rubber is also beneficial to increasing the physical and even chemical adsorption of broken C-S bonds and high-polarity acrylonitrile when breakage is formed by repeated flexing, increasing the branching and passivating degree of the breakage, reducing apparent breakage and increasing flexing resistance.

The Applicant has found that if nitrile rubbers with too high a viscosity or too high an acrylonitrile content are used, the elasticity and the flexural resistance of the mixtures according to the invention are adversely affected by too high a crosslinking density or by polarity.

Plasticizer

The plasticizer is added into the polymer material to increase the plasticity of the polymer, so that the performance of the polymer material can be improved, the production cost is reduced, and the production benefit is improved. The plasticizer mainly has the effects of weakening the secondary valence bonds among resin molecules, increasing the mobility of the molecular bonds of the resin, reducing the crystallinity of the resin molecules, increasing the plasticity of the resin molecules, enhancing the flexibility of the resin molecules, being easy to process, being legally applicable to industrial application, and being widely existed in food packaging, cosmetics, medical devices and environmental water. Such as cling film, food packaging, toys, etc. Plasticizers include saturated fatty acid esters, phthalates (dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), dioctyl phthalate (DOP), Butyl Benzyl Phthalate (BBP), di-2-ethyl hexyl phthalate (DEHP), dioctyl phthalate (DOP), diisononyl phthalate (DINP), benzene polyesters, benzoates, polyol esters, chlorinated hydrocarbons, epoxies, citrates, polyesters, and the like. Wherein the long-term contact of the phthalate ester can cause chronic poisoning to human body, especially can affect the endocrine system and reproductive system of human, therefore, nowadays, the countries in Europe and America have gradually made strict regulations or direct forbidding on toys, food, daily necessities, medical supplies, textiles and the like which are added with the phthalate ester plasticizer.

In one embodiment, the plasticizer of the present invention is a fatty acid ester plasticizer.

The aliphatic dibasic acid ester plasticizer has the advantages of excellent low-temperature performance, high plasticizing efficiency and good viscosity performance, but has poor compatibility, oil resistance and electrical insulation performance compared with phthalate, and is expensive, and most of the aliphatic dibasic acid ester plasticizer is used as a plasticizer aid. The aliphatic dibasic acid esters are classified into saturated fatty acid dibasic acid esters and unsaturated fatty acid dibasic acid esters. The unsaturated fatty acid dibasic acid ester can be copolymerized with vinyl monomers due to the double bond contained in the molecule, and can be used as an internal plasticizer, such as di (2-ethyl) hexyl adipate (DOA), so that the plasticizing efficiency is high, the thermal discoloration is small, and the good low-temperature flexibility and light resistance can be endowed to products; the disadvantages are high volatility, poor water resistance, migration resistance and electric insulation and high price. In a preferred embodiment, the plasticizer of the present invention is a saturated fatty acid ester plasticizer.

Preferably, the plasticizer comprises short-chain saturated fatty acid ester and long-chain saturated fatty acid ester, and the weight ratio of the short-chain saturated fatty acid ester to the long-chain saturated fatty acid ester is 1: (0.01 to 0.1); further, the weight ratio of the short-chain saturated fatty acid ester to the long-chain saturated fatty acid ester is 1: 0.05.

the short-chain saturated fatty acid ester is a saturated fatty acid ester with a chain length of less than or equal to 25, and comprises but is not limited to succinate, glutarate, adipate, suberate, azelate and sebacate, and in a preferred embodiment, the short-chain saturated fatty acid ester is selected from one or more of di (2-ethyl) adipate (DOA), di (2-ethyl) adipate (DOS), di-sec-octyl sebacate (DCS) and dibutyl sebacate (DBS); in a more preferred embodiment, the short chain saturated fatty acid ester of the present invention is di (2-ethyl) hexyl adipate, available from Shangyng Shanghai chemical Co., Ltd.

The long-chain saturated fatty acid ester is a saturated fatty acid ester with a chain length of more than 25, and includes, but is not limited to, WB222, WB212, WB42 and WA48 of struktol; in a more preferred embodiment, the long chain saturated fatty acid ester of the present invention is struktol's WB 222.

The applicant has surprisingly found that when short-chain saturated fatty acid esters and long-chain fatty acid esters are used as dispersants, the dispersion of the nitrile rubber and the filler is promoted, and the tensile strength and elasticity are promoted while the increase in the yield resistance is also facilitated. This is probably because, by adding short-chain saturated fatty acid ester, such as diisooctyl adipate and long-chain saturated fatty acid ester, such as WB222, on one hand, the short-chain saturated fatty acid ester, such as isooctyl adipate, has a shorter alkyl chain and is compatible with nitrile rubber, and the ester group and the alkyl chain in the molecule can respectively isolate the nitrile group and the molecular chain in nitrile rubber, and on the other hand, the long-chain saturated fatty acid ester, such as WB222, shields the nitrile group in nitrile rubber, and simultaneously, the low-polarity long alkyl chain forms micelles, and through the shielding and micelle effects of the two, the acting force between nitrile rubbers can be further reduced, so that the viscosity is further reduced, the flow of nitrile rubber is promoted, the dispersion between nitrile rubber and filler is promoted, thereby promoting the exertion of the filler reinforcing effect, and increasing the tensile strength and the elongation at break; in addition, in the repeated flexing process, compared with nitrile rubber, the fatty acid ester plasticizer with lower molecular weight can move smoothly in the flexing process, so that abrasion caused by interaction between molecular chains in the flexing process is reduced, and because of larger polarity difference of saturated fatty acid ester, particularly long-chain saturated fatty acid ester and nitrile rubber, the long-chain saturated fatty acid ester tends to be adsorbed on the surfaces of carbon black and zinc oxide, the separation between the zinc oxide and a nitrile rubber matrix in the repeated flexing process is reduced, and the increase of flexing resistance is facilitated.

Anti-aging agent

the rubber and its products are gradually sticky, hardened, brittle or cracked under the action of heat, oxygen, ozone, valence-changing metal ions, mechanical stress, light, high-energy rays, other chemical substances, mold and the like during long-term storage and use, and the physical and mechanical properties and elasticity of the rubber and its products are gradually reduced to completely lose the use value as the aging process progresses and develops, therefore, certain chemical substances are added into the rubber and its products to improve the resistance to the above destructive effects, and the aging process is delayed or inhibited, so that the storage period and the service life of the rubber and its products are prolonged, and the substances are called anti-aging agents.

In one embodiment, the antioxidant of the present invention is antioxidant RD.

The anti-aging agent RD is suitable for natural rubber and synthetic rubber such as butyronitrile, butylbenzene, ethylene propylene, chloroprene and the like, has excellent effect of preventing aging caused by heat and oxygen, but has poor effect of preventing flex aging. In a preferred embodiment, the antioxidant RD of the present invention is obtained from Zhengzhou double strength chemical products, Inc.

In a preferred embodiment, in the vulcanization of the present invention, primary vulcanization and secondary vulcanization are sequentially carried out; further, the temperature of primary vulcanization is 160-180 ℃, and the time is 4-6 min; furthermore, the temperature of the secondary vulcanization is 130-150 ℃, and the time is 50-80 min.

Examples

The present invention will be specifically described below by way of examples. It should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and that the insubstantial modifications and adaptations of the present invention by those skilled in the art based on the above disclosure are still within the scope of the present invention.

A1: nitrile rubber

The nitrile rubber is 1846F from the Langshan Perbunan series of Germany.

A2: nitrile rubber

The nitrile rubber is 2845F of the Langshan Perbunan series of Germany.

A3: nitrile rubber

The nitrile rubber is 2870F of the langerhans Perbunan series of germany.

B1: filler material

The filler was carbon black, available from Spheron SO-LP of Cambot.

B2: filler material

The filler was carbon black, available from Spheron 4000-LP of Cambot.

B3: filler material

The filler was carbon black, available from Vulcan 6-LP of cabot.

B4: filler material

The filler was zinc oxide, available from Nks132, national island nacarton new materials science and technology ltd.

C1: plasticizer

The plasticizer is adipic acid di (2-ethyl) hexyl ester and is purchased from Shangying Shanghai Shandong Shanghai Kagaku Kogyo Co.

C2: plasticizer

The plasticizer is bis (2-ethyl) hexyl sebacate, and is purchased from Shangying Shanghai Shandong Shanghai Kagaku Kogyo Co.

C3: plasticizer

The plasticizer is WB222 from struktol.

C4: plasticizer

The plasticizer is Struktol WB 212.

D: sulfur

The sulfur was purchased from Zhongya chemical Co., Ltd.

E1: vulcanization accelerator

The vulcanization accelerator is N-cyclohexyl-2-benzothiazole sulfonamide and is purchased from Zhengzhou double-strength chemical products Co.

E2: vulcanization accelerator

The vulcanization accelerator is tetramethyl thiuram disulfide, which is purchased from Zhengzhou double-strength chemical products Co.

F: softening agent

The softener is stearic acid, available from PALMATA 1801 of indolylboro.

G: anti-aging agent

The anti-aging agent is an anti-aging agent RD purchased from Zhengzhou double-strength chemical products Limited company.

TABLE 1

Examples	1	2	3	4	5	6	7
								A1	100	90	120	100	100	100	100
A2
								A3
B1	60	50	70	65			50
								B2					60
B3						60
								B4	5	5	5		5	5	15
C1	10	8	12	10	10	10	10
								C2
C3	0.5	0.5	0.5	0.5	0.5	0.5	0.5
								C4
D	0.6	0.6	0.6	0.6	0.6	0.6	0.6
								E1	1.5	1.5	1.5	1.5	1.5	1.5	1.5
E2	1.5	1.5	1.5	1.5	1.5	1.5	1.5
								F	1	1	1	1	1	1	1
G	1	1	1	1	1	1	1

Attached table 1

Examples 1-13 provide low polycyclic aromatic hydrocarbon compounds having the formulations shown in Table 1, in parts by weight.

Embodiments 1 to 13 provide a low polycyclic aromatic hydrocarbon compound, including the following steps:

mixing: and adding sulfur, a vulcanization accelerator and a softening agent into the premix, mixing, and then sequentially carrying out primary vulcanization and secondary vulcanization to obtain the rubber compound, wherein the temperature of the primary vulcanization is 170 ℃, the time is 5min, and the temperature of the secondary vulcanization is 140 ℃, and the time is 60 min.

Evaluation of Performance

1. Polycyclic aromatic hydrocarbon content: the low content polycyclic aromatic hydrocarbon compound provided in examples 1-3 was prepared according to AfPS GS 2014: 01PAK method test, 18 kinds of aromatic hydrocarbons are analyzed by GC-MS, wherein MDI is the detection limit of the method, ND is not detected, namely < MDI, "-" is not specified, 18 kinds of aromatic hydrocarbons are not detected when the MDL is 0.1mg/kg, which indicates that the content of the 18 kinds of aromatic hydrocarbons is less than 0.1mg/kg, and meets the standard of 1 kind of materials in the GS certification of AfPS, wherein Table 2 is the detection result of the mixed rubber provided by example 1, MDI is the detection limit of the method, ND is not detected, namely < MDI, "-" is not specified.

TABLE 2 polycyclic aromatic Hydrocarbon test results

2. Tensile strength: the low-content polycyclic aromatic hydrocarbon compounds provided in the examples were subjected to tensile strength tests in accordance with GB T528-1992 and rated in terms of tensile strength, wherein 1 is a tensile strength of more than 10MPa and not more than 12MPa, 2 is a tensile strength of more than 12MPa and not more than 14MPa, 3 is a tensile strength of more than 14MPa and not more than 16MPa, and 4 is a tensile strength of more than 16MPa, as shown in Table 3.

3. Elongation at break: the low-content polycyclic aromatic hydrocarbon compounds provided in the examples were tested for elongation at break according to GB T528-1992 and rated, with a rating of 1 being 200% or less, a rating of 2 being greater than 200% and 240% or less, a rating of 3 being greater than 240% and 270% or less, a rating of 4 being greater than 270% and 300% or less, and a rating of 5 being greater than 300% and the results are given in Table 3.

4. Flex resistance: the low-content polycyclic aromatic hydrocarbon compounds provided in the examples were subjected to a flex resistance test in accordance with GB/T13934-1992, and the degree of cracking was measured at 15 ten thousand flex times, the results being shown in Table 3.

TABLE 3 mechanical Properties test

Examples	Tensile strength	Elongation at break	Flexibility of bending resistance
				1	4 stage	Grade 5	Level 1
2	4 stage	Grade 5	Level 1
				3	4 stage	Grade 5	Level 1
4	Stage 2	Grade 3	Grade 3
				5	Grade 3	Grade 5	Grade 5
6	4 stage	4 stage	Stage 2
				7	Grade 3	Grade 3	Grade 5
8	Grade 3	Stage 2	4 stage
				9	Grade 3	Grade 3	Grade 6
10			Grade 3
				11			Grade 5
12			Stage 2
				13			Stage 2

5. And (3) performance characterization test: the hardness, tensile strength, elongation at break, tear strength, stress at elongation at break of 100%, 200% and 300%, density, primary vulcanization shrinkage and secondary vulcanization shrinkage of the low-content polycyclic aromatic hydrocarbon compound as provided in example were measured, and the results are shown in Table 4.

Table 4 characterization test of properties

The test results in table 2 show that the low-content polycyclic aromatic hydrocarbon rubber compound provided by the invention has low polycyclic aromatic hydrocarbon content, meets the AfPS GS detection standard, and can avoid harm of polycyclic aromatic hydrocarbon to human body; in addition, as can be seen from the results in tables 3 and 4, by using appropriate raw materials and preparation processes, it is also advantageous to improve the mechanical properties and the like, to obtain a rubber compound with good comprehensive properties, and to further expand the application range.

The foregoing examples are merely illustrative and serve to explain some of the features of the method of the present invention. The appended claims are intended to claim as broad a scope as is contemplated, and the examples presented herein are merely illustrative of selected implementations in accordance with all possible combinations of examples. Accordingly, it is applicants' intention that the appended claims are not to be limited by the choice of examples illustrating features of the invention. Also, where numerical ranges are used in the claims, subranges therein are included, and variations in these ranges are also to be construed as possible being covered by the appended claims.

Claims

1. A low-content polycyclic aromatic hydrocarbon rubber compound is characterized in that the content of benzo (a) pyrene in the rubber compound is less than 0.1mg/kg, and the content of benzo (e) pyrene in the rubber compound is less than 0.1 mg/kg.

2. A low-content polycyclic aromatic hydrocarbon compound according to claim 1, wherein the compound is prepared from 90 to 120 parts by weight of a nitrile rubber, 55 to 75 parts by weight of a filler, 8 to 13 parts by weight of a plasticizer, 0.1 to 0.8 part by weight of sulfur, 2 to 5 parts by weight of a vulcanization accelerator, 0.1 to 2 parts by weight of a softener and 0.1 to 2 parts by weight of an antioxidant.

3. A low-content polycyclic aromatic hydrocarbon compound according to claim 2, wherein said nitrile rubber has a Mooney viscosity ML1+4 at 100 ℃ of 40 to 50 and an acrylonitrile content of 25 to 30% by weight.

4. A low polyaromatic content rubber compound according to claim 2, wherein the filler is selected from one or more of carbon black, talc, kaolin, zinc oxide, alexane, white carbon, china clay, calcium carbonate, stone black, sericite and illite.

5. A low polycyclic aromatic hydrocarbon compound as claimed in claim 4, wherein the filler comprises carbon black and zinc oxide in a weight ratio of (10 to 15): 1.

6. a low-content polycyclic aromatic hydrocarbon compound according to claim 4, wherein the carbon black has an average particle diameter of 40 to 60nm and a specific surface area of 34 to 55m²/g。

7. A low polycyclic aromatic hydrocarbon compound according to any one of claims 2 to 6, wherein the plasticizer comprises a short-chain saturated fatty acid ester and a long-chain saturated fatty acid ester in a weight ratio of 1: (0.01-0.1).

8. A low polycyclic aromatic hydrocarbon compound in accordance with claim 2, wherein the vulcanization accelerator is one or more selected from the group consisting of sulfonamide vulcanization accelerators, thiuram vulcanization accelerators, guanidine vulcanization accelerators, dithiocarbamate vulcanization accelerators and thiazole vulcanization accelerators.

9. A low polycyclic aromatic hydrocarbon compound in accordance with claim 2, wherein the softening agent is selected from one or more of mineral oil, animal and vegetable oil, and fatty acid.

10. A method for preparing a low polycyclic aromatic hydrocarbon compound according to any one of claims 1 to 9, comprising the steps of: