CZ35745U1 - Porous polymer material with recycled content - Google Patents

Description

In the registration procedure, the Industrial Property Office does not determine whether the subject of the utility model meets the conditions for eligibility for protection pursuant to Section 1 of Act no. No. 478/1992 Coll.

CZ 35745 UI

Porous polymer material with recycled content

Field of technology

The technical solution relates to the preparation of a porous polymer mass which contains recycled materials and which can be used in the production of die casting molds for sanitary ware.

State of the art

Sanitary ceramics are produced by casting ceramic tiles into porous molds. The original porous molds were gypsum, casting was carried out at atmospheric pressure, the production cycle was long and the molds usually had to be replaced after about 80 pieces of castings. For the purposes of series production, gypsum molds are increasingly being replaced by molds made of porous polymer mass, on which ceramic products are pressed at high pressures. The acquisition costs of polymer molds are significantly higher, but more than 15,000 castings can be produced on them without any problems.

The composition of porous polymeric materials for die casting, their production processes and their applications are described in a number of patents and publications. One of the basic patents is DE 1928026 A1, which describes a porous material produced by curing a water-in-oil emulsion containing polymerizable vinyl monomers. The main components of this material are:

(a) water which forms pores in the final mass;

b) powdered homopolymers and copolymers of esters of methacrylic acid, styrene, vinyl acetate, vinyl chloride and the like, or mixtures thereof;

c) liquid water-emulsifiable polymerizable monomers, such as methyl methacrylate, styrene and the like, or mixtures thereof with unsaturated polyesters, the polymerization of which solidifies and solidifies the whole mass;

d) nonionic surfactants with wetting agent to facilitate dispersion of the polymer powders;

e) nonionic surfactants with emulsifier function based on a poloxamer triblock copolymer (polyethylene glycol - block - polypropylene glycol - block polyethylene glycol or PEG-PPG-PEG) with a polyethylene glycol (PEG) content of 20 to 70% for the preparation of a water-in-oil emulsion ; and

f) an initiator of the polymerization of the monomers mentioned under c) on the basis of a combination of an organic peroxide, e.g. benzoyl peroxide, with an accelerator, usually a tertiary amine, e.g. N, N-dimethyl-p-toluidine.

The formulations and mass production processes described in DE 1928026 A1 are the basic principle on which the current technological processes for the production of commercially available die-casting materials with a typical pore size in the range of 5 to 40 mm are based.

Other patents describe various modifications of recipes or processes which make it possible to set specific properties of the porous material and, if necessary, to influence its price.

E.g. According to EP 0516224 B1, the pore size in the range of 1 to 5 [mu] m can be regulated by the addition of sodium tetraborate decahydrate and the shrinkage of the mold during curing can be significantly reduced by the addition of short glass fibers with a length of 1 to 6 mm. With this pore size, which is approximately in the region of the pore size of the gypsum, the molds can be used for the production of ceramics both at atmospheric pressure and for pressing at elevated pressure up to 6 * 10 ⁵ Pa. The patent also claims the application of granular fillers with spherical or spheroidal particles, such as glass or ceramic, solid and hollow microspheres, polymer granules, and the application of multifunctional crosslinking agents, such as divinylbenzene or diacrylates or dimethacrylates, which allow insoluble polymer networks to form during mass curing.

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According to the utility model CZ 32336 UI, it is possible to control the pore size, and thus the permeability of polymer materials for die casting of sanitary ceramics, by a suitable combination of two emulsifiers based on triblock copolymers of the poloxamer type with different composition.

EP 2583995 A1 describes the preparation of porous polymeric compositions using polar comonomers such as epoxy methacrylate or ethylene glycol methacrylate and with the addition of metal powders, mainly aluminum, as fillers which have a mean pore radius in the range of 0.1 to 10 .mu.m.

In the production of porous polymer molds for die casting of sanitary ceramics, cured polymeric wastes are generated. These wastes have the same chemical composition and the same or similar physical and mechanical properties as the cured mass of the polymer mold. The sources of waste are: residues from the cleaning of the equipment in which the mixture was mixed, chips from mechanical processing - milling - hardened molds and possibly produced non-functional molds, ie whole molds that do not meet the quality requirements for the application.

These wastes belong to the category of hazardous waste and require special disposal procedures, which further increases the cost of mold production.

Another and at the same time the largest source of waste porous polymeric materials are end-of-life molds, which have been decommissioned from the ceramics press, usually due to irreversible clogging of the pores.

The proposed technical solution makes it possible to partially recycle the waste in question as fillers in the production of new porous polymer molds, thus contributing to the reduction of material production costs and to the reduction of the environmental impacts of the production of porous polymer molds.

In none of the available patents is the application of recycled mold production waste in the production of new molds claimed.

The essence of the technical solution

Polymeric material with defined pore size and containing recyclates suitable for the production of porous molds for die casting of sanitary ceramics, produced by curing a water-in-oil emulsion, is characterized in that it contains as main components:

(a) a mixture of polymer powders based on polymethyl methacrylate (PMMA) or copolymers of methyl methacrylate;

b) a liquid mixture of polymerizable vinyl monomers;

c) a nonionic emulsifier for preparing a water-in-oil emulsion and for facilitating wetting of polymer powders;

d) free radical polymerization initiator;

e) water;

f) water-soluble inorganic salts; and

g) solid powdered recycled polymer.

Polymeric powders ad a) are produced by suspension or emulsion polymerization of methyl methacrylate or its copolymerization with other vinyl monomers, such as ethyl acrylate, butyl acrylate, butyl methacrylate, styrene or others, their particles have a spherical or spheroidal shape with an average size of 20 to 700 μm and their content in the polymer mass is 45 to 59% by weight.

The liquid mixture of polymerizable vinyl monomers ad b) contains methyl methacrylate and styrene, or further contains multifunctional vinyl monomers such as divinylbenzene, ethylene glycol dimethacrylate and others, which allow the formation of insoluble polymer networks during

-2GB 35745 UI curing. The content of the liquid mixture of polymerizable vinyl monomers ad b) in the polymer mass is usually 16 to 19% by weight.

The nonionic emulsifier ad c) comprises one or a mixture of several polypropylene glycol (PPG) and polyethylene glycol (PEG) poloxamer copolymers with a total polyethylene glycol content of at least 20% by weight. The emulsifier is further characterized in that the relative molecular weight of the polypropylene glycol block in all the block copolymers used is at least 2,700 g / mol and the total content of emulsifier in the polymer mass is usually higher than 0.25% by weight.

The free-radical polymerization initiator ad d) consists of a mixture of dibenzoyl peroxide and a tertiary amine, e.g. N, N-dimethyl-p-toluidine, in customary amounts in the range from 0.10 to 0.30% by weight. for peroxide and 0.05 to 0.15 wt. for a tertiary amine.

Water ad e) can be demineralized or potable, preferably with a low content of dissolved minerals. The total water content of the polymer is usually 22 to 26% by weight. The water may further comprise the addition of a wetting agent in a total amount in the polymer mass of 0.01 to 0.1% by weight, which will allow easier wetting and dispersion of the polymer powders ad a). Conventional nonionic surfactants with an HLB of 3 to 12 or, preferably, the same nonionic emulsifier according to ad c) can be used as wetting agents.

The water may further contain dissolved inorganic salts ad f) such as chlorides, bromides, sulfates, phosphates, and others, in amounts up to 0.1% by weight. in the polymer mass, which affect the viscosity of the polymer mass during casting and allow the pore size and water permeability to be regulated through the cured polymer mass.

Solid recyclates ad g) consist of a hardened polymeric mass for the production of porous molds for die casting of sanitary ceramics, which were prepared from residues after cleaning of containers used for casting new molds or from residues after mechanical processing of new mold or from non-functional mold or from unpolluted part of mold end-of-life by milling from the original block, with possible subsequent grinding and / or sieving. The solid recyclates are further characterized in that they have a particle size in the range of 0.01 to 1.0 mm and their total content in the mixture is 0.1 to 13 wt.

The process for producing the porous material, the mixing conditions and casting processes, and the further processing of the cured mold are not different from the usual practices established in the art. Curing of the water-in-oil emulsion is achieved by free-radical polymerization of the reactive vinyl monomers present in the liquid mixture.

It has been shown that recycled material from the residues of porous polymer molds for die casting of sanitary ware can be used in the production of new porous polymer molds as a partial replacement for the original polymer powders. Molds made with the addition of recycled material have an overall porosity, pore size and mechanical properties suitable for die casting sanitary ware.

For the possibility of application on an operational scale in the casting of large molds, it is crucial to achieve suitable flow properties of the mixed casting mass. The flow properties of the casting material are favorably influenced by the content of the crosslinked fraction in the recycled material. Recyclates with a low gel content of up to 2% by weight have been shown to be. up to a content of 5% by weight can be applied in the formulation of the polymer casting compound for the production of the porous mold, recyclates with a gel content of more than 28% by weight can be applied. can be dosed into the casting polymer mass up to a content of 13% by weight.

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Examples of technical solutions

Example 1 (reference) - Casting polymer mass for the production of porous molds for die casting sanitary ware without the addition of recycled material

0.06 g (0.025% by weight) of anhydrous sodium sulfate and 0.05 g (0.021% by weight) of PEG-PPG poloxamer EM-1 emulsifier are dissolved in 57.6 g (23.9% by weight) of demineralized water. -PEG with a PEG content of 40% and a molar mass of approximately 5900 g / mol. Then 37 g (15.3% by weight) of the original PMMA-1 powder with an average particle size of 100 mm and 56.6 g (23.5% by weight) of the original PMMA-2 powder with an average particle size of 45 mm are added. The mixture is homogenized for 20 minutes while cooling to 15-17 ° C. This will create premix No. 1.

In the second vessel, premix No. 2 is prepared as follows. 0.14 g (0.058%) was dissolved in a mixture of 31.4 g (13.0% by weight) of methyl methacrylate, 7.8 g (3.23% by weight) of styrene and 1.6 g (0.663% by weight) of ethylene glycol dimethacrylate. ) N, N-dimethyl-p-toluidine and 0.63 g (0.261% by weight) of an EM-1 emulsifier of the poloxamer type PEG-PPG-PEG with a PEG content of 40% and a molar mass of approximately 5900 g / mol. The mixture is cooled to 15-17 ° C. 0.3 g (0.124% by weight) of benzoyl peroxide (75% purity) is added to this solution, which dissolves with stirring for 120 s. Immediately thereafter, 48 g (19.9% by weight) of the original powder are added. PMMA-1 with an average particle size of 100 mm and stirring is continued for another 60 s. After this time, aqueous premix No. 1 is added to the resulting dispersion and the resulting mixture is dispersed for another 60 s. A homogeneous stable dispersion is formed, which is immediately poured into molds and allow to cure for 75 minutes. The resulting porous mass is washed with water.

The formulation and the resulting properties of the cast and cured porous masses such as flowability, apparent porosity, mean pore radius, water permeability through the mass and compressive stress value at a relative deformation of 5% are given in Table I (Example 1, formulation A).

Example 2 - Casting polymer mass for the production of porous molds for die casting of sanitary ceramics with the addition of recycled REC-1, which is characterized by a low gel content

0.06 g of anhydrous sodium sulfate and 0.05 g (0.025% by weight) of PEG-PPG-PEG poloxamer EM-1 emulsifier containing PEG 40 are dissolved in 57.6 g (23.9% by weight) of demineralized water. %. The original PMMA-1 and PMMA-2 powders and REC-1 recycled powder with a mean particle size of 320 mm and a gel content of 1% are then added. The mixture is homogenized for 20 minutes while cooling to 15-17 ° C. This creates a premix no.

In the second vessel, premix No. 2 is prepared as follows. 0.14 g (0.058%) was dissolved in a mixture of 31.4 g (13.0% by weight) of methyl methacrylate, 7.8 g (3.23% by weight) of styrene and 1.6 g (0.663% by weight) of ethylene glycol dimethacrylate. N, N-dimethyl-p-toluidine and 0.63 g (0.261% w / w) PEG-PPG-PEG poloxamer EM-1 emulsifier with a PEG content of 40%. The mixture is cooled to 15-17 ° C. 0.3 g (0.124% by weight) of benzoyl peroxide (75% purity) is added to this solution and it dissolves with stirring for 120 s. Immediately thereafter, the required dose of the original PMMA powder OP-1 is added and stirring is continued for further After this time, the entire aqueous premix No. 1 is added to the resulting dispersion and the resulting mixture is stirred vigorously for another 30 seconds. A homogeneous stable dispersion is formed, which is immediately poured into molds and allowed to cure for 75 minutes. The resulting porous mass is washed with water.

The formulations and the resulting properties of the cast and cured porous materials are given in Table I (Example 2, formulations B to E). The hardened materials achieve properties suitable for application in the production of porous molds for die casting of sanitary ceramics, however, due to decreasing fluidity with increasing recycled content, only recipes with recycled content REC-1 up to 5% by weight can be applied in practice (recipes B and C).

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Example 3 - Casting polymer mass for the production of porous molds for die casting of sanitary ceramics with the addition of recycled REC-2, which is characterized by a high gel content

The formulations and the preparation procedure are the same as in Example 2. Only instead of recycled REC-1, recycled REC-2 is used, which has a mean particle size of 220 mm and a gel content of 31% by weight.

The formulations and the resulting properties of the cast and cured porous materials are given in Table II (Example 3, formulations F to I). The hardened materials achieve properties suitable for application in the production of porous molds for pressure casting of sanitary ceramics, in addition, they are characterized by excellent flowability in the entire tested range of recycled REC-2.

Example 4 - Casting polymer mass for the production of porous molds for die casting of sanitary ceramics with the addition of recycled material at the level of 9.9% while maintaining the permeability to water

The preparation procedure is the same as in Example 2. REC-2, characterized by a high gel content, is used as the recycle and partial modifications of the recipe are made.

The formulation and the resulting properties of the casting and curing porous mass are given in Table II (Example 4, formulation J). A casting composition is obtained which can be applied in the pressure casting of sanitary ware and which is characterized by water permeability at the level of the recycled-free mass (Example 1, recipe A).

Example 5 - Casting polymer mass for the production of porous molds for die casting of sanitary ceramics with the addition of recycled material at the level of 9.9%> while maintaining the mechanical properties

The preparation procedure is the same as in Example 2. REC-2, characterized by a high gel content, is used as the recycle and partial modifications of the recipe are made.

The formulation and the resulting properties of the casting and curing porous mass are given in Table II (Example 5, formulation K). A casting composition is obtained which can be applied in the pressure casting of sanitary ware and which is characterized by a compressive stress value at 5% deformation at the level of the recycled-free mass (Example 1, recipe A).

Example 6 - Casting polymer mass for the production of porous molds for die casting of sanitary ceramics by recycled additive at the level of 9.9% with an alternative emulsifier

The preparation procedure is the same as in Example 2. Only instead of the EM-1 emulsifier, an alternative EM-2 emulsifier of the PEG-PPG-PEG poloxamer type with a PEG content of 30% and a molar mass of approximately 5800 g / mol is used. REC-2, characterized by a high gel content, is used as the recycle and partial modifications of the recipe are made.

The formulation and the resulting properties of the casting and curing porous mass are given in Table II (Example 6, formulation L). A casting composition is obtained which can be applied in the pressure casting of sanitary ware and which has similar properties to the composition produced on the basis of the EM-1 emulsifier (Example 4, recipe J).

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Table I (Examples 1 and 2)

Example 1 2 Recipe AND B C D E Premix No. 1 Demineralized water (% by weight) 23.9 23.9 23.9 23.9 23.9 Sodium sulphate (% by weight) 0.025 0.025 0.025 0.025 0.025 EM-1 emulsifier (% by weight) 0.021 0.021 0.021 0.021 0.021 EM-2 emulsifier (% by weight) - - - - - Original PMMA-1 powder (% by weight) 15.3 13.8 10.3 5.22 3.73 Original PMMA-2 powder (% by weight) 23.5 22.5 21.5 19.5 18.5 Recycled powder REC-1 (% by weight) - 2.49 4.98 9.95 12.4 REC-2 recycled powder (% by weight) - - - - - Premix No. 2 Methyl methacrylate (% by weight) 13.0 13.0 13.0 13.0 13.0 Styrene (% by weight) 3.23 3.23 3.23 3.23 3.23 Ethylene glycol dimethacrylate (% by weight) 0.663 0.663 0.663 0.663 0.663 EM-1 emulsifier (% by weight) 0.261 0.261 0.261 0.261 0.261 EM-2 emulsifier (% by weight) - - - - - N, N-dimethyl-p-toluidine (% by weight) 0.058 0.058 0.058 0.058 0.058 Dibenzoyl peroxide (% by weight) 0.124 0.124 0.124 0.124 0.124 Original PMMA-1 powder (% by weight) 19.9 19.9 19.9 19.9 19.9 Properties of matter Mixture flow (%) ^a) 96.9 95.8 95.4 71.5 61.1 Apparent porosity (% vol.) ^B) 28.1 29.5 30.5 30.7 30.8 Pore radius (pm) ^c) 7.5 8.2 8.4 8.4 8.7 Water flow ^d) 0.075 0.074 0.094 0.082 0.094 Deformation pressure (MPa) ^e) 27.9 28.7 27.5 22.4 22.2

Explanations:

^(a) the percentage of casting material which flows out of a 32 ml beaker through an opening 6 mm in diameter between 30 and 180 s from the mixing of the mixture; for successful application on an operational scale, the parameter "Flowability of the mixture" must reach at least 90% ^b) according to ČSN EN 993-1 ^c) mercury porosimetry ^d) in kg / min through a layer of material with an area of 1 cm ² and a thickness of 1 cm; at the value of pressure loss before and after the layer 1 * 10 ⁵ Pa ^e) value of compressive stress at relative deformation 5%

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Table II (Examples 3, 4, 5 and 6)

Example 3 4 5 6 Recipe F G H AND J TO L Premix No. 1 Demineralized water (% by weight) 23.9 23.9 23.9 23.9 24.9 22.9 24.9 Sodium sulphate (% by weight) 0.025 0.025 0.025 0.025 0.025 0.025 0.025 EM-1 emulsifier (% by weight) 0.021 0.021 0.021 0.021 0.021 0.021 - EM-2 emulsifier (% by weight) - - - - - - 0.012 Original PMMA-1 powder (% by weight) 13.8 10.3 5.22 3.73 4.11 10.4 5.22 Original PMMA-2 powder (% by weight) 22.5 21.5 19.5 18.5 18.9 14.1 18.4 Recycled powder REC-1 (% by weight) - - - - - - - REC-2 recycled powder (% by weight) 2.49 4.98 9.95 12.4 9.95 9.95 9.94 Premix No. 2 Methyl methacrylate (% by weight) 13.0 13.0 13.0 13.0 13.8 14.3 14.6 Styrene (% by weight) 3.23 3.23 3.23 3.23 3.48 3.57 3.68 Ethylene glycol dimethacrylate (% by weight) 0.663 0.663 0.663 0.663 0.373 0.373 0.414 EM-1 emulsifier (% by weight) 0.261 0.261 0.261 0.261 0.261 0.261 - EM-2 emulsifier (% by weight) - - - - - - 0.248 N, N-dimethyl-p-toluidine (% by weight) 0.058 0.058 0.058 0.058 0.058 0.058 0.116 Dibenzoyl peroxide (% by weight) 0.124 0.124 0.124 0.124 0.124 0.124 0.248 PMMA OP-1 powder (% by weight) 19.9 22.0 24.0 24.0 24.1 24.0 22.3 Properties of matter Mixture flow (%) ^a) 96.9 96.7 95.7 93.2 93.4 96.6 96.6 Apparent porosity (% vol.) ^B) 29.3 28.7 30.1 29.8 31.1 28.9 30.2 Pore radius (pm) ^c) 8.2 7.8 7.2 6.7 7.2 7.3 - Water flow ^d) 0.079 0.068 0.058 0.058 0.069 0.050 0.082 Deformation pressure (MPa) ^e) 29.6 27.3 25.4 22.6 24.9 27.1 23.4

Explanations:

$ the percentage of the casting mass which flows out of the 32 ml spout cup through a hole at a diameter of 6 mm between 30 and 180 s from the mixing of the mixtures; for a successful application on an operational scale, the parameter "Mixture fluidity" must reach at least 90% according to ČSN EN 993-1 ^h) mercury porosimetry ^υ in kg / min through a layer of material with an area of 1 cm ² and a thickness of 1 cm; at the value of pressure loss before and after the layer 1 * 10 ⁵ Pa ů value of compressive stress at relative deformation 5%

Industrial applicability

The porous polymer material containing recycled material can be used industrially for the production of molds for pressure casting of sanitary ceramics such as washbasins or toilet bowls, or as a frit for the production of filter materials. The proposed solution with the addition of recycled material contributes to the reduction of material costs and to the reduction of the environmental impacts of the production of porous polymer molds.

CZ 35745 UI

Claims (4)

PROTECTION REQUIREMENTS A polymeric composition containing recycled polymer recycled material, suitable for the production of porous molds for die casting of sanitary ceramics, characterized in that it comprises: a) 45 to 59% by weight mixtures of two polymer powders based on polymethyl methacrylate with different average particle sizes; b) 16 to 19 wt. liquid mixtures of polymerizable vinyl monomers; c) 0.25 to 0.30 wt. a polyethylene glycol-block polypropylene glycol-block-polyethylene glycol triblock copolymer containing 30 to 40% polyethylene glycol and a molar mass of 5800 to 5900 g / mol; d) mixtures of 0.1 to 0.2 wt. of dibenzoyl peroxide and 0.05 to 0.15 wt. N, N-dimethyl-p-toluidine as a radical polymerization initiator; e) 22 to 26% by weight of water; f) 0.02 to 0.03 wt. anhydrous sodium sulfate; and g) recycled polymeric recycled material derived from cured waste polymeric materials from the production or application of porous polymeric molds for die casting sanitary ware. Recycled polymeric composition according to Claim 1, characterized in that the recycled polymeric composition contains less than 2% of gel and its amount in the polymer composition is 0.1 to 5% by weight. Recycled polymeric composition according to Claim 1, characterized in that the recycled polymeric composition contains more than 28% of gel and its amount in the polymer composition is 0.1 to 13% by weight. Recycled polymeric composition according to Claim 1, characterized in that a mixture of methyl methacrylate, styrene and ethylene glycol dimethacrylate is used as the liquid mixture of polymerizable vinyl monomers, the ethylene glycol dimethacrylate content of this mixture being 2 to 4% by weight. and the weight ratio of methyl methacrylate to styrene is 4: 1.