Disposable stone paper foamed tableware produced by gypsum powder and preparation method

DISPOSABLE STONE PAPER FOAMED TABLEWARE PRODUCED
BY GYPSUM POWDER AND PREPARATION METHOD
SUMMARY
The invention provides a disposable stone paper foamed tableware produced with gypsum powder and
a preparation method thereof. It is composed of the following components in parts by weight: 77 to 90%
of gypsum powder, 7 to 13% of polypropylene, 0.5 to 1.5% of surface modifier, 0.5 to 2.5% of foaming
agent, degradation Agent 0.5-1.5%, compatibilizer 0.5-1.5%, processing aid 1-3%. It is prepared
through the steps of surface modification, mixing and molding of gypsum powder. The disposable stone-
paper foamed tableware prepared by the invention has good water resistance, strong oil resistance,
good thermal insulation effect, high strength, light specific gravity, good load-bearing ability, and can be
environmentally degraded within 15 to 90 days. The product is degraded Later it can also be used as
soil conditioner and fertilizer. It is the newest environmentally degradable stone paper packaging
material.
1. A disposable stone-paper foamed tableware produced with gypsum powder, characterized in that it
consists of the following weight percentages composition:
Gypsum powder 77～90%
Polypropylene 7～13%
Surface modifier 0.5～1.5%
Foaming agent 0.5～2.5%
Degrading agent 0.5～1.5%
Compatibilizer 0.5～1 .5%
Processing aid 1～3%,
The sum of the above components is 100%.
2. The production of disposable stone-paper foamed tableware with gypsum powder according to claim
1, wherein the gypsum powder is food grade gypsum powder calcined at a high temperature of 400 to
1100°C, with a particle size of 325 Mesh ~ 1250 mesh.
1, wherein the polypropylene is injection-grade polypropylene or extrusion-grade polypropylene.
1, wherein the surface modifier is a silane coupling agent, a titanate coupling agent, and an aluminate
coupling agent. One or more of the following agents, compound coupling agents or stearic acid.
5. The disposable stone-paper foamed tableware produced from gypsum powder according to claim 1,
wherein the foaming agent is azodicarbonamide.
6. The disposable stone-paper foamed tableware produced with gypsum powder according to claim 1,
wherein the degradation agent is dicumyl peroxide.
WUHAN VISIGHT INTERNATIONAL CO., LTD
Page 1 of 10 www.vi-sight.com

1, wherein the compatibilizer is one of PP～g～MAH, PP～g～HDPE graft copolymer Kind or several.
8. The production of disposable stone paper foamed tableware with gypsum powder according to claim
1, wherein the processing aid is one or more of chlorinated paraffin, zinc stearate, zinc oxide, etc.
9. A preparation method of disposable stone paper foamed tableware produced with gypsum powder,
characterized in that the following steps are carried out:
(1) Prepare materials according to the following percentages by weight:
The sum of the above components is 100%;
(2) Surface modification of gypsum powder: dry the gypsum powder in step (1) at 150-300°C for 2 to 4
hours, and surface modification
The agent is mixed and modified at 120～180℃ for 5～8 minutes to obtain the surface modified material;
(3) Mixing: Add polypropylene and compatibilizer to the surface modification material of step (2) and
mix for 10 minutes to obtain a mixture; then add the mixture, foaming agent, degrading agent, and
processing aid Perform banburying at 100-160°C for 10-15 minutes, then melt-extrusion pelletizing at
120-180°C to obtain pellets;
(4) Molding: The pellets obtained in step (3) are injection molded at an injection temperature of 270-
300°C, an injection pressure of 90-120 MPa, and a mold temperature of 60-90°C to obtain disposable
stone-paper foamed tableware; or, The pellets obtained in step (3) are fed into a conventional extruder
with extruder temperature 180-200°C, die temperature 190-220°C, and cooling temperature 30-70°C
for melt extrusion to obtain stone paper foamed sheets Then, the obtained stone-paper foamed sheet
is conventionally punched or blister-shaped to obtain a disposable stone-paper foamed tableware.
TECHNICAL FIELD
[0001]
The present invention belongs to the technical field of stone papermaking, and specifically relates to a
disposable stone paper foamed tableware produced with gypsum powder and a preparation method
thereof.
BACKGROUND TECHNIQUE
[0002]
China has abundant reserves of natural gypsum mineral resources, with a total reserve of nearly 60
billion tons, ranking first in the world. Gypsum is a monoclinic mineral, and its main chemical component
is calcium sulfate (CaSO4) hydrate. As a widely used industrial material and building material, through

the efforts of domestic researchers, gypsum has been widely used in cement retarders, gypsum building
products, model making, medical food additives, sulfuric acid production, paint fillers, gypsum whiskers,
etc. In the field, the application prospects of gypsum are quite broad, and further research and
development of the application areas of gypsum resources are needed.
[0003]
According to incomplete statistics, my country currently consumes approximately 15-50 billion
disposable tableware every year. Among them, PS disposable foam tableware is mainly used, and some
are PP disposable tableware, disposable paper tableware and degradable disposable tableware.
Foreign research results show that the polystyrene polymer in disposable PS foam tableware is in the
process of synthesis. If it is not completely polymerized, it will cause the dissolution of styrene
monomers, dimers, and trimers. If absorbed by the human body for a long time, it will cause damage to
the liver and kidneys. Styrene, the monomer of polystyrene, has strong irritation. It can also produce
anesthesia at high concentrations, and cause adverse effects and harm to the central and peripheral
nervous system, and it isn't easy to degrade. The state has explicitly prohibited it. PP disposable blister
tableware is not easy to foam due to the influence of PP melt strength. Compared with PS foam
tableware, it has low strength, insufficient hardness, and high cost, which cannot fully meet the market
demand. Although disposable paper tableware does not harm the environment, its low strength and
high price affect its sales in the market. Due to the high cost of degradable disposable tableware, market
promotion is more complicated.
[0004]
Stone paper is a new type of packaging material that has been developed in my country in recent years
and is characterized by low carbon, energy saving, and recyclability. Stone paper has the dual
characteristics of ordinary fiber paper and plastic products, and can be widely used in food, medicine,
stationery, toys, electronic products, disposable tableware and other outer packaging fields. Application
Publication No. CN104710685A discloses a stone paper tableware and a preparation method thereof,
including the following components by weight: 60-80 parts of calcium carbonate, 18-43 parts of
polyethylene, 18-43 parts of polypropylene, 0.5-1 part of antioxidant, 0.5 to 1.5 parts of resin ACR
adhesive, 1.5 to 2.5 parts of composite stabilizer modifier, 25 to 35 parts of wood fiber powder; its
preparation method includes:
(1) Put the raw materials into the mixer in a certain proportion for high-speed mixing;
(2) Modification: The mixing machine will fully disperse and knead the matched raw materials into strips
or sheets;
(3) Granulation: Use a granulator to make the obtained strips or sheets into pellets, which is convenient
for transportation and can provide raw materials for multiple parallel production lines to improve
production efficiency;
(4) The pellets are extruded and blown into the desired product. Although the stone paper tableware
produced by this method has certain advanced characteristics, the stone paper produced by using
calcium carbonate powder and wood fiber powder as the main material and using polyethylene and
polypropylene as auxiliary materials is only a physical blending modification. The difference in the
process is only to use calcium carbonate powder and wood fiber powder to crush it, which is an

incompletely degradable material. In addition, the produced stone paper has a large proportion and a
high price, which cannot be compared with the price of PS disposable foam tableware, which affects its
promotion and application to a certain extent.
SUMMARY OF THE INVENTION
[0005]
The purpose of the present invention is to overcome the above-mentioned drawbacks. The present
invention provides a disposable stone paper foamed tableware produced with gypsum powder and a
preparation method thereof.
[0006]
The technical scheme of the present invention is realized as follows: a disposable stone paper foamed
tableware produced with gypsum powder, which is composed of the following components by weight
percentage:
The sum of the above components is 100%.
[0007]
The gypsum powder is a food-grade gypsum powder obtained by calcination at a high temperature of
400 to 1100° C., with a particle size of 325 mesh to 1250 mesh, and the color is preferably white.
[0008]
The polypropylene is injection-grade polypropylene or extrusion-grade polypropylene. The melt flow
rate MFR of injection molding grade polypropylene is controlled at 4-22g/10min (100℃, 2160g), and the
melt flow rate MFR of extrusion grade polypropylene is controlled at 2-5g/10min (100℃, 2160g).
[0009]
The surface modifier is one or more of silane coupling agent, titanate coupling agent, aluminate coupling
agent, composite coupling agent or stearic acid.
[0010]
The blowing agent is azodicarbonamide (AC).
[0011]
The degradation agent is dicumyl peroxide (DCP).

[0012]
The compatibilizer is one or more of graft copolymers such as PP~g~MAH, PP~g~HDPE.
[0013]
The processing aid is one or more of chlorinated paraffin, zinc stearate, zinc oxide and the like.
[0014]
The second object of the present invention is to provide a preparation method of disposable stone-
paper foamed tableware produced with gypsum powder, through the following steps:
(2) Surface modification of gypsum powder: dry the gypsum powder in step (1) at 150-300°C for 2 to 4
hours, and send it to a high-speed mixer to mix and modify the surface modifier at 120-180°C for 5 to 8
minutes to get the surface modified material;
(3) Mixing: Add polypropylene and compatibilizer to the surface modification material of step (2) and
mix for 10 minutes to obtain a mixture; then add the mixture, foaming agent, degrading agent, and
processing aid Perform banburying in an internal mixer at 100-160°C for 10-15 minutes, and then send
it to the extruder at 120-180°C for melt extrusion granulation to obtain pellets;
(4) Molding: The pellets obtained in step (3) are injection molded in a conventional injection molding
machine at an injection temperature of 270-300°C, an injection pressure of 90-120MPa, and a mold
temperature of 60-90°C to obtain a disposable stone paper foam Tableware; or, the pellets obtained in
step (3) are sent to a conventional extruder at 180-200°C, die temperature 190-220°C, and cooling
temperature 30-70°C for melt extrusion to obtain Stone-paper foamed sheet, and then the obtained
stone-paper foamed sheet is punched or blister-formed in a conventional manner to obtain disposable
stone-paper foamed tableware.
[0015]
Compared with the prior art, the present invention has the following beneficial effects:
The disposable stone paper foamed tableware prepared by the invention has good water resistance,
strong oil resistance, good thermal insulation effect, high strength and light specific gravity (compared
with the current unfoamed stone paper, the weight is reduced by 15-30 %). It has good load-bearing
capacity and can be environmentally degraded within 15 to 90 days. After the product is degraded, it
can also be used as a soil amendment and fertilizer. It is a newest environmentally degradable stone
paper packaging material.

[0016]
1. In the present invention, modified food grade calcium sulfate is used as the main raw material, and
then blended and modified with polypropylene and a compatibilizer to produce disposable tableware.
Not only has the amount of inorganic powder added has been greatly increased, and the weight
percentage per 1,000 kg has reached 77-90%, which greatly reduces the production cost and can be
promoted and applied in the market.
[0017]
2. The present invention uses gypsum powder to improve product hardness, elastic modulus,
dimensional stability and thermal deformation temperature. The disposable stone paper foamed snack
box prepared by the present invention contains 100 ℃ hot water, 150 The edible oil is soaked in ℃
for 1 hour, the deformed weight is ≥1000 kg, does not leak, does not deform, and the load is 1000 kg
without deformation, making it a highly competitive and practical tableware.
[0018]
3. The present invention uses the microporous structure of gypsum to form a loose network structure
inside the stone paper through the action of a foaming agent, which not only increases the strength of
the stone paper, but also reduces the specific gravity of the stone paper.
[0019]
4. The present invention takes advantage of the strong hygroscopicity of gypsum and is conducive to
improving soil structure. Through the introduction of DCP azodicarbonamide, the use of organic
peroxides will generate a large number of free radicals when heated. It can attack the tertiary carbon
atoms of polypropylene, accelerate the breaking of macromolecular chains, and promote the
degradation of polypropylene. The use of the present invention to prepare disposable foamed stone
paper tableware can be environmentally degraded within 15 to 90 days, and the degradation products
not only return Nature can also be used as soil conditioner and fertilizer. It is a newest environmentally
degradable stone paper packaging material.
DESCRIPTION OF THE DRAWINGS
[0020]
Figure 1 is a schematic diagram of the process flow of the present invention.

DETAILED DESCRIPTION
[0021]
The present invention will be described in detail through the following examples. It is necessary to point
out that the following examples are only used to further illustrate the present invention and cannot be
understood as limiting the scope of protection of the present invention. Those skilled in the art are based
on the above-mentioned present invention. SUMMARY OF THE INVENTION Some non-essential
improvements and adjustments made to the present invention still belong to the protection scope of the
present invention.
[0022]
Example 1
Gypsum powder 90%
Injection grade polypropylene 7%
Silane coupling agent 0.5%
Azodicarbonamide 0.5%
Dicumyl peroxide 0.5%
Surface Modification of Gypsum Powder
Mixing
Extrusion Granulation
One-Step (Injection Molding) Two-Step (Extrusion Pull Tab)
Stamping Blister Molding

PP～g～MAH 0.5%
Zinc stearate 1%,
The gypsum powder is a food-grade gypsum powder calcined at a high temperature of 400°C, with a
particle size of 325 mesh;
(2) Surface modification of gypsum powder: Dry the gypsum powder in step (1) at 150°C for 4 hours,
and send it to a high-speed mixer to mix and modify the surface modifier at 120°C for 8 minutes to
obtain a surface modified material ；
(3) Mixing: Add polypropylene and compatibilizer to the surface modification material of step (2) and mix
for 10 minutes to obtain a mixture; then add the mixture, foaming agent, degrading agent, and
processing aid Perform banburying in an internal mixer at 100°C for 15 minutes, and then send it to the
extruder to melt, extrude and pelletize at 120°C to obtain pellets;
(4) Molding: the pellets obtained in step (3) are injection-molded in a conventional injection molding
machine at an injection temperature of 300°C, an injection pressure of 120MPa, and a mold temperature
of 60°C to obtain disposable stone-paper foamed tableware.
[0023]
Example 2
Gypsum powder 84%
Extrusion grade polypropylene 10%
Surface modifier 1%
Azodicarbonamide 1%
Dicumyl peroxide 1%
PP～g～HDPE 1%
Processing aid 2%,
The gypsum powder is a food-grade gypsum powder obtained by calcination at a high temperature of
600°C, with a particle size of 1000 mesh and a white color; the surface modifier is a titanate coupling
agent and an aluminate coupling agent; The processing aids are zinc stearate and zinc oxide.
(2) Surface modification of gypsum powder: the gypsum powder in step (1) is dried at 200°C for 3 hours,
then fed into a high-speed mixer and mixed with a surface modifier at 160°C for 6 minutes to obtain a
surface Modified material
(4) Forming: The pellets obtained in step (3) are fed into a conventional extruder and melted and
extruded at a temperature of 180-200°C, a die temperature of 195°C, and a cooling temperature of 30°C
to obtain a stone paper foam Then, the obtained stone-paper foamed sheet is punched or blister-molded
according to the conventional method to obtain a disposable stone-paper foamed tableware.

[0024]
Example 3
Gypsum powder 77%
Extrusion grade polypropylene 13%
Surface modifier 1.5%
Azodicarbonamide 2.5%
Dicumyl peroxide 1.5%
Compatibilizer 1.5%
Processing aid 3%,
The gypsum powder is a food-grade gypsum powder calcined at a high temperature of 1100°C, with a
particle size of 1250 mesh; the surface modifier is a composite coupling agent and stearic acid; the
compatibilizer is PP～g ~MAH and PP~g~HDPE; the processing aids are chlorinated paraffin and zinc
oxide.
(2) Surface modification of gypsum powder: the gypsum powder in step (1) was dried at 300°C for 2
hours, then fed into a high-speed mixer and mixed with a surface modifier at 180°C for 5 minutes to
obtain a surface Modified material
(4) Forming: The pellets obtained in step (3) are fed into a conventional extruder at 180～200℃, die
temperature 220℃, cooling temperature 60℃ for melt extrusion to obtain stone paper foam Then, the
obtained stone-paper foamed sheet is punched or blister-formed in a conventional manner to obtain a
disposable stone-paper foamed tableware.
[0025]
Example 4
Same as Example 1, only replace step (4) with: the pellets obtained in step (3) are injection molded in
a conventional injection molding machine at an injection temperature of 270°C, an injection pressure of
90MPa, and a mold temperature of 90°C to obtain a disposable stone Paper foam tableware.
[0026]
Example 5 is the same as Example 3, except that step (4) is replaced with: the pellets obtained in step
(3) are fed into a conventional extruder with an extruder temperature of 180°C, a die temperature of
190°C, and cooling Melt and extrude at a temperature of 70°C to obtain a stone paper foamed sheet,
and then the obtained stone paper foamed sheet is subjected to conventional punching or blister
molding to obtain a disposable stone paper foamed tableware.
[0027]
Comparative Example 1: Conventional PS foam snack box.

[0028]
Comparative Example 2: The stone paper tableware disclosed in the application publication number
CN104710685A.
[0029]
Example 1, Example 2, and Example 3 were made into stone-paper foamed tableware of the same
specifications (length × width × depth = 190 × 130 × 45mm), and the performance comparison with
comparative examples 1 and 2 The following table
Performance
CMPR
1
CMPR
2
EXAM
1
EXAM
2
EXAM
3
Deformation temperature (°C) ≤70 100 125 123 120
Water resistance (@100°C water) Good Good Good Good Good
Oil resistance (@150°C vegetable oil 1h) Good Good Good Good Good
Deformation weight (g) 500 1000 1050 1100 1150
Heat preservation Good General Good Good Good
Harm to people Yes No No No No
Degradation time (d)
No
degraded
Partial
Degraded
15 25 18

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