Preparation method of beads for evanescent mode casting and expandable resin obtained by using preparation method

Abstract

The invention relates to a preparation method of beads for evanescent mode casting, comprising the following steps: S1, dissolving a monomer methyl methacrylate, an initiator, a dispersant and a secondary dispersant into water, polymerizing at the temperature of 75-85 DEG C to obtain an intermediate product; and S2, dissolving the intermediate product, a foaming agent, the dispersant and the second dispersant into water, and dipping at the temperature of 100-150 DEG C at the pressure of 0.5-1.5 MPa to obtain expandable beads. The invention also relates to an expandable resin obtained by the preparation method disclosed by the invention. According to the invention, the initiator is added in the step S1, and the foaming agent is added in the step S2, thus radically eliminating the inhibitory effect of the foaming agent on polymerization reaction of free radicals and improving yield and quality of beads.

Description

technical field

[0001] The invention relates to beads for lost foam casting, more particularly to a method for preparing beads for lost foam casting and the expandable resin obtained therefrom. Background technique

[0002] Lost foam casting is a new type of casting technology developed in recent years, known as the casting technology of the 21st century. In the lost foam casting process, the performance of the mold material is a key factor affecting the quality of the casting.

[0003] The earliest mold material used was expandable polystyrene (EPS). However, when using this mold material for pouring, there are the following problems: due to the difficulty in thermal decomposition of EPS, it is decomposed in a disordered fracture mode, and it is easy to produce asphalt-like substances, which will cause wrinkles on the surface of the casting, cooling scars, surface depressions, and surface defects. Slag inclusions, etc., seriously affect the quality of castings; in additio...

Examples

preparation example Construction

[0020] The preparation method of beads for lost foam casting according to the present invention includes two steps, wherein the first step is carried out in a normal pressure reactor, and the second step is carried out in a stainless steel autoclave, as mentioned in the US patent application US4790367A For devices that require nitrogen protection such as shot-add tanks, the equipment of the present invention is simple and requires less investment, and is easy to operate and is suitable for small-scale production, especially for industries with small market demand for beads for lost foam casting. In addition, the intermediate products obtained in the first step can be sold separately, which is more flexible and convenient for small enterprises.

[0021] In the first step, the monomer methyl methacrylate, initiator, dispersant, and auxiliary dispersant are dissolved in water, and polymerized at 75-85 degrees to obtain an intermediate product. This step is carried out in a normal...

Embodiment 1

[0027] In a normal-pressure reactor, dissolve 100 parts of monomer methyl methacrylate, 0.5 parts of initiator benzoyl peroxide, 0.5 parts of dispersant tricalcium phosphate, and 0.01 part of assistant dispersant sodium dodecylbenzenesulfonate In 300 parts of water, polymerize at 75 degrees to obtain an intermediate product.

[0028] The intermediate product was sieved.

[0029] In the autoclave, dissolve 100 parts of intermediate product, 5 parts of blowing agent isopentane, 0.5 part of dispersant tricalcium phosphate, and 0.1 part of auxiliary dispersant sodium dodecylbenzene sulfonate in 100 parts of water. and 0.5MPa to obtain expandable beads.

Embodiment 2

[0031] In a normal-pressure reactor, dissolve 100 parts of monomer methyl methacrylate, 2 parts of initiator benzoic acid peroxide, 5 parts of dispersant magnesium hydroxide, and 0.1 part of assistant dispersant sodium dodecylbenzenesulfonate in 900 parts of water, polymerized at 85 degrees to obtain an intermediate product.

[0032] The intermediate product was sieved.

[0033] In the autoclave, 100 parts of the intermediate product, 10 parts of the mixture of the blowing agent n-pentane and isopentane with a mass ratio of 1:4, 5 parts of the dispersant magnesium hydroxide, and 1 part of the auxiliary dispersant dodecyl Sodium benzenesulfonate was dissolved in 300 parts of water, and soaked at 150 degrees and 1.5MPa to obtain expandable beads.

technical field

[0001] The invention relates to beads for lost foam casting, more particularly to a method for preparing beads for lost foam casting and the expandable resin obtained therefrom. Background technique

[0002] Lost foam casting is a new type of casting technology developed in recent years, known as the casting technology of the 21st century. In the lost foam casting process, the performance of the mold material is a key factor affecting the quality of the casting.

[0003] The earliest mold material used was expandable polystyrene (EPS). However, when using this mold material for pouring, there are the following problems: due to the difficulty in thermal decomposition of EPS, it is decomposed in a disordered fracture mode, and it is easy to produce asphalt-like substances, which will cause wrinkles on the surface of the casting, cooling scars, surface depressions, and surface defects. Slag inclusions, etc., seriously affect the quality of castings; in additio...

Examples

preparation example Construction

[0020] The preparation method of beads for lost foam casting according to the present invention includes two steps, wherein the first step is carried out in a normal pressure reactor, and the second step is carried out in a stainless steel autoclave, as mentioned in the US patent application US4790367A For devices that require nitrogen protection such as shot-add tanks, the equipment of the present invention is simple and requires less investment, and is easy to operate and is suitable for small-scale production, especially for industries with small market demand for beads for lost foam casting. In addition, the intermediate products obtained in the first step can be sold separately, which is more flexible and convenient for small enterprises.

[0021] In the first step, the monomer methyl methacrylate, initiator, dispersant, and auxiliary dispersant are dissolved in water, and polymerized at 75-85 degrees to obtain an intermediate product. This step is carried out in a normal...

Embodiment 1

[0027] In a normal-pressure reactor, dissolve 100 parts of monomer methyl methacrylate, 0.5 parts of initiator benzoyl peroxide, 0.5 parts of dispersant tricalcium phosphate, and 0.01 part of assistant dispersant sodium dodecylbenzenesulfonate In 300 parts of water, polymerize at 75 degrees to obtain an intermediate product.

[0028] The intermediate product was sieved.

[0029] In the autoclave, dissolve 100 parts of intermediate product, 5 parts of blowing agent isopentane, 0.5 part of dispersant tricalcium phosphate, and 0.1 part of auxiliary dispersant sodium dodecylbenzene sulfonate in 100 parts of water. and 0.5MPa to obtain expandable beads.

Embodiment 2

[0031] In a normal-pressure reactor, dissolve 100 parts of monomer methyl methacrylate, 2 parts of initiator benzoic acid peroxide, 5 parts of dispersant magnesium hydroxide, and 0.1 part of assistant dispersant sodium dodecylbenzenesulfonate in 900 parts of water, polymerized at 85 degrees to obtain an intermediate product.

[0032] The intermediate product was sieved.

[0033] In the autoclave, 100 parts of the intermediate product, 10 parts of the mixture of the blowing agent n-pentane and isopentane with a mass ratio of 1:4, 5 parts of the dispersant magnesium hydroxide, and 1 part of the auxiliary dispersant dodecyl Sodium benzenesulfonate was dissolved in 300 parts of water, and soaked at 150 degrees and 1.5MPa to obtain expandable beads.