RU2527468C1 - Method of producing highly filled polyvinyl chloride-based wood-polymer composition - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method of producing highly filled wood-polymer composition includes pretreatment of wood flour with an aqueous solution of a binding agent - silica sol, followed by thorough mixing and drying to constant weight at temperature of 100±2°C and further mixing of the treated wood flour, polyvinyl chloride (PVC), complex heat stabiliser and impact strength modifier. The PVC is pretreated with a binding agent containing 0.1-2.5 pts.wt silica sol, thoroughly mixed, dried to constant weight at temperature of 60±2°C, and the wood flour is treated with a binding agent containing 0.1-4.9 pts.wt silica sol. Content of the ingredients is as follows, pts.wt: PVC - 100, wood flour - 50-220, complex heat stabiliser - 4.5-7, impact strength modifier - 4.8-9, binding agent - 0.2-7.4.

EFFECT: wood-polymer materials based on the obtained highly filled PVC composition have an improved melt flow index, high tensile strength and thermal stability.

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Description

The invention relates to a technology for the production of polyvinyl chloride (PVC) compositions using wood flour as an organic filler for the manufacture of highly filled wood-polymer materials.

A known method of obtaining a wood-polymer composition comprising wood particles, a polyolefin and an inorganic silica additive. The preparation of the polymer composition is carried out as follows: the wood filler is metered into the paddle mixer and silicon dioxide is added with stirring and the particles of the thermoplastic polymer or their mixture are added in portions in 2-3 doses. Mixing is carried out until a homogeneous mixture is obtained. Further, various materials and products are made from the obtained polymer composition [RF Patent 2049662, cl. B27N 3/00, 2004].

The main disadvantage of the composition is the high melt viscosity during processing into products and low manufacturability, which limits the technology of processing composites into products only by pressing methods.

A known method of obtaining a wood-polymer composition based on a thermoplastic polymer binder, including dispersed wood filler, polyelectrolyte, a crosslinking agent, organic peroxide and target additives. According to the invention, ground wood filler, mainly wet, is treated with a polyelectrolyte and dried. Then the dry filler is impregnated with monomer, and the impregnation can be carried out at the final stage of drying the wood filler, for example, immediately before the precipitating cyclone or in the batcher of the dry chip bin. Next, the manufactured filler is mixed with the rest of the components of the mixture, also flowing through metering devices. If necessary, preliminary thermoplastic polymer is mixed with peroxide and target additives. The resulting composition is then processed by pressing and extrusion [RF Patent 2132347, cl. C08L 97/02, 1999].

The disadvantages are the complex technology for preparing the composition and the high cost of the introduced components, in particular a crosslinking agent.

Closest to the claimed method for producing a highly filled wood-polymer composition by the set of essential features is a method for producing a wood-polymer composition containing polyvinyl chloride, wood filler, a complex thermal stabilizer, impact modifier and a binding agent. According to the invention, wood flour is pre-impregnated with aqueous solutions of binders - silica sol or multilayer carbon tubes, thoroughly mixed and dried at 102 ± 3 ° C to constant weight, while the silica concentration in the wood flour is 0.01-10%, and the degree of filling of wood -polymer composition is 26-60 wt.% modified wood flour [RF Patent 2465292 C1, June 27, 2012].

The main disadvantage of the composition obtained by this method is the low melt flow rate.

The objective of the invention is to obtain highly filled (organic filler content of more than 50 wt.%) Wood-polymer compositions based on polyvinyl chloride and dispersed wood flour with an improved set of basic technological and operational characteristics.

EFFECT: improved melt flow rate of a highly filled PVC-based wood-polymer composition. The technical result is achieved in that in a method for producing a highly filled wood-polymer composition based on polyvinyl chloride, which consists in pretreating wood flour with an aqueous solution of a binding agent - silica sol, followed by thorough mixing and drying to constant weight at a temperature of 100 ± 2 ° C and further mixing processed wood flour, polyvinyl chloride, complex heat stabilizer and impact modifier, according to the invention, PVC is pre-treated with a binder they agent containing 0.1-2.5 pbw silica sol, thoroughly mixed, dried to constant weight at a temperature of 60 ± 2 ° C, and wood flour is treated with a binder agent containing 0.1-4.9 wt.h. silica sol and with the following ingredients (parts by weight):

PVC - 100;

Wood flour - 50-220;

Integrated thermal stabilizer - 4.5-7;

Impact modifier - 4.8-9;

The binding agent is silica sol - 0.2-7.4.

The analysis of the technique and the identification of sources containing information about analogues of the claimed invention made it possible to establish that no analogues were found that are characterized by signs that are identical to all the essential features of the claimed invention. Therefore, the claimed invention meets the condition of "novelty."

To obtain a wood-polymer composition based on PVC, components were used that satisfy the following requirements:

Suspension polyvinyl chloride grade C7058M (GOST 14332-78)

Integrated thermal stabilizer, for example, Interstab (certificate No. 99-00244)

Impact modifier, e.g. FM-22

Wood flour brand 180 (GOST 16361-87)

Silica sol (silica sol) is a colorless or slightly colored yellowish or grayish colloidal solution. The stability of the colloidal system is ensured by the content of sodium hydroxide in the solution; therefore, the solution has an alkaline reaction (pH = 10.3). The density of silica sol is 1.2 g / cm ³ , the concentration of silicon dioxide is 330-340 g / l, the concentration of sodium oxide is 0.34 g / l.

For studies of PVC compositions, samples were obtained in the form of films. A method of obtaining a highly filled wood-polymer composition based on PVC was carried out as follows. Wood flour was treated with an aqueous solution of a binding agent containing 0.1-4.9 wt.h. silica sol, thoroughly mixed and dried to constant weight at a temperature of 100 ± 2 ° C. Separately, PVC was treated with an aqueous solution of a binding agent containing 0.1-2.5 wt.h. silica sol was also thoroughly mixed and dried to constant weight at a temperature of 60 ± 2 ° C. Then, the obtained processed wood flour and PVC were mixed with a complex thermal stabilizer in an amount of 4.5-7 parts by weight. and impact modifier in the amount of 4.8-9 wt.h. per 100 parts by weight PVC Film samples were prepared by thermoplastication on laboratory rollers with a 1: 1.25 friction at a roll temperature of 140-180 ° C for 5-6 minutes, depending on the composition. Rolling was carried out with a thickness of the gap between the rollers of 8-13 microns.

To study the properties of the composition obtained by the claimed method, PVC compositions were prepared containing 100 parts by weight of treated PVC, impact modifier FM-22 - 7 parts by weight, complex thermal stabilizer - 5.5 parts by weight, processed wood flour (pine) - 50-220 parts by weight (compositions 1-5).

The properties of compositions with different degrees of filling are presented in table 1.

Table 1 Indicator Melt Flow Index (MFI), g / 10 min Filler (per 100 parts by weight of PVC) Thermostability, min Tensile strength, MPa No wood flour (control) 32 0.31 72 Raw wood flour (unprocessed): 50 parts by weight 32 0.21 81 70 parts by weight or 40 wt.% (max.) 26 0.16 85 Crafted. PVC (100 parts by weight). Processed Wood Flour: 1) 50 parts by weight 38 0.34 95 2) 80 parts by weight 36 0.23 105 3) 120 parts by weight 33 0,07 115 4) 160 parts by weight 28 0.03 120 5) 220 parts by weight (Max.) 21 0.02 132 Prototype: 40 parts by weight 36 0.32 86 80 parts by weight 34 0.18 one hundred 120 parts by weight thirty 0.03 110 160 parts by weight (Max.) 27 0.01 118

The maximum degree of filling of the proposed rigid PVC compositions compared to the prototype was increased from 160 to 220 parts by weight. wood flour per 100 parts by weight PVC At the same time, the melt flow rate, tensile strength and thermal stability are improved.

Claims (1)

A method of obtaining a highly filled wood-polymer composition based on polyvinyl chloride, which consists in pretreating wood flour with an aqueous solution of a binding agent - silica sol, followed by thorough mixing and drying to constant weight at a temperature of 100 ± 2 ° C and further mixing the treated wood flour, polyvinyl chloride, a complex thermal stabilizer and impact modifier, characterized in that the polyvinyl chloride is pre-treated with a binder, containing 0.1-2.5 mass. . silica sol, thoroughly mixed, dried to constant weight at a temperature of 60 ± 2 ° C, and wood flour is treated with a binder agent containing 0.1-4.9 wt.h. silica sol, and the following content of ingredients, parts by weight:
polyvinyl chloride one hundred wood flour 50-220 complex thermal stabilizer 4,5-7 impact modifier 4.8-9 binding agent - silica sol 0.2-7.4.