WO2001051563A1

WO2001051563A1 - Injection molding composition comprising paper and method for preparing the same

Info

Publication number: WO2001051563A1
Application number: PCT/KR2001/000048
Authority: WO
Inventors: Min-Soo Lee
Original assignee: Kgreenworld Co., Ltd.
Priority date: 2000-01-14
Filing date: 2001-01-12
Publication date: 2001-07-19
Also published as: AU2001227139A1; KR20010086308A

Abstract

The present invention relates to an injection molding composition, particularly to an injection molding comprising a paper or a pulp as a main material and a method for preparing the same. The present invention provides for an injection composition comprising a) a paper or a pulp; b) at least one aliphatic polyester compound represented by chemical formula (1), and c) a starch, and a method for preparing the same, wherein R1 and R2 are independently substituted or unsubstituted alkyl group with straight or branched type of 1 to 20 carbon numbers, n is repeating unit of polymerization.

Description

INJECTION MOLDING COMPOSITION COMPRISING PAPER AND METHOD FOR PREPARING THE SAME

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to an injection molding composition, more

particularly, to an injection molding composition comprising paper or pulp, and a

method for preparing an injection molded product comprising paper or pulp.

(b) Description of the Related Art

Earlier molded products comprising paper or pulp have been

manufactured by an extrusion molding process. However, since extrusion molding machines are expensive, production costs using this method are high.

A molded product comprising paper or pulp is preferably manufactured by an injection molding process for lowering manufacturing cost. Generally,

materials subject to the injection molding process should be soft and durable at

high temperatures. However, as paper or pulp is used as the main material, it is

difficult to obtain these molding properties, and since the injection molding

process is performed at high temperatures, paper and pulp are easily scorched

or deformed.

On the other hand, a golf tee is an implement for supporting a golf ball

and is cut when the golf ball is hit by a golf club. The cut golf tee becomes a

pollutant when not gathered from the golf field. Thus, it is necessary that the

golf tee is strong enough to support a golf ball and at the same time to be biodegradable. A conventional wooden golf tee has good supporting strength,

however it becomes a pollutant, taking about 1 to 3 years to erode. The

wooden golf tee also consumes, scarce natural resources during its production,

and as it is difficult to mass-produce, the costs of production are further

increased.

Thus, there is a need of an injection molded product that is quickly

decomposable and strong so as to be applicable for a golf tee.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an injection molding

composition comprising paper or pulp. It is another object to provide an

injection molded product mainly made from paper or pulp and a method for

manufacturing the same, which is durable, strong and quickly decomposable so

as to be applicable for a golf tee.

In order to achieve these objects, the present invention provides an

injection molding composition containing paper or pulp comprising:

a) paper or pulp;

b) an aliphatic polyester represented by the following Chemical

Formula 1 ; and

c) starch

[Chemical Formula 1]

wherein,

Ri and R₂ are respectively substituted or non-substituted linear or

branched C^Cao alkyl, and n is the degree of polymerization ranging from 3 to

20,000.

The present invention also provides a method of preparing an injection

molded product containing paper or pulp, comprising the steps of:

a) adding paper or pulp and starch into water and mixing them;

b) drying the mixture of step a);

c) grinding the dried mixture of step b);

d) adding an aliphatic polyester represented by the above Chemical

Formula 1 to the ground mixture of step c) and mixing the

combination; and

e) introducing the mixture of step d) into an injection molding machine

and injection molding the mixture.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following detailed description, only the preferred embodiment of

the invention has been shown and described, simply by way of illustration of the

best mode contemplated by the inventors in carrying out the invention. As will

be realized, the invention is capable of modification in various obvious respects, all without departing from the invention. Accordingly, the descriptions are to be

regarded as illustrative in nature, and not restrictive.

According to the present invention, in order to obtain an injection

molded product comprising paper or pulp by an injection molding, an aliphatic

polyester represented by the above Chemical Formula 1 is added during the

injection molding process.

Although other polymers such as polyethylene and polypropylene are

suitable for an injection molding because they can make a composition soft, since the injection molding process is performed at a high temperature, the

paper or pulp in the composition is burned or scorched, and these polymers

have characteristics of low decomposition and their incineration brings about pollution.

On the other hand, the aliphatic polyester represented by the above

Chemical Formula 1 is soft and thus has good molding properties, and enables the injection molding process to be performed at a low temperature under low

pressure. Furthermore, the aliphatic polyester erodes easily at a low

temperature and thus does not cause pollution in the case of natural

decomposition or incineration.

The injection molding composition according to the present invention

contains starch, which additionally improves molding properties and

decomposability. Wheat, potato, tapioca, and corn can be used as starch.

Starch can be added to water, or mixed with it after it is cooked. Generally, it is satisfactorily cooked after one to 10 minutes at a temperature ranging from 80

°C to 100 °C.

The injection molding composition of the present invention uses paper

or pulp as a main material. Common paper or pulp can be used, and waste

paper is preferable because using waste paper makes it more possible to cut

down the production cost and limit pollution to the environment.

The injection molding composition according to the present invention

may further comprises various inorganic fillers in order to additionally increase

strength. Preferably, inorganic fillers selected from a group consisting of

calcium carbonate, talc, titanium dioxide, silica powder, wollastonite, clay and a mixture thereof can be used, which can generally pass through a 200 mesh

sieve and even more preferably through a 325 mesh sieve. The average particle size of the inorganic filler is from 5 μm to 20 μm, and if the size exceeds

this range, it will be difficult to obtain a molded product having good

appearance.

To the injection molding composition according to the present invention,

it is desirable to add one or more compounds represented by the following

Chemical Formula 2.

[Chemical Formula 2]

wherein,

R₃ is hydrogen or substituted or non-substituted linear or branched

R₄is hydrogen or methyl; and m is the degree of polymerization ranging

from 3 to 20,000.

The injection molding composition according to the present

invention is desirable to be added together with vinyl acetate and ethyl acrylate

among the compounds represented by the above Chemical Formula 2.

Preferably, the injection molded product according to the present

invention comprises;

a) 100 weight parts of paper or pulp;

b) 2 to 70 weight parts of an aliphatic polyester represented by the

above Chemical Formula 1 ;

c) 2 to 50 weight parts of starch;

d) 2 to 20 weight parts of one or more kinds of inorganic fillers,

when it is needed; and

e) 2 to 70 weight parts of one or more compounds represented by

the above Chemical Formula 2 when it is needed The injection molded product comprising paper or pulp according

to the present invention is preferably prepared in the following manner.

First, starch is stirred with water, and paper or pulp is added.

After drying, the mixture is ground. The drying temperature is preferably 100 °C

5 to 150 °C. During the grinding step, the dried mixture is ground enough to be

mixed in a rudder, and it is preferable to grind the mixture such that the mixture

can pass totally through a 10 mesh sieve.

Further, an aliphatic polyester represented by the above Chemical

Formula 1 is added to the ground mixture, and the ground mixture is introduced 10 into the injection molding machine and undergoes the injection molding process

at a constant temperature, preferably ranging from 120 °C to 160 °C.

When paper or pulp is added, it is desirable to add the inorganic fillers. The compound represented by Chemical Formula 2 is preferably added

with starch. 15 The density of the injection molded product according to the

present invention can be controlled from 0.3 g/cm³ to 0.8 g/cm³ according to its

composition. Its bending strength is 15 MPa toward a longitudinal direction and

50 MPa toward a transverse direction, which is stronger than that of natural

wood which has bending strength of 10 MPa toward longitudinal direction and

20 60 MPa toward a transverse direction.

While the present invention has been described in detail with

reference to the preferred embodiments, those skilled in the art will appreciate that various modifications and substitutions can be made thereto without

departing from the spirit and scope of the present invention as set forth in the

appended claims.

[Examples]

Example 1

5 g of wheat starch, 5 g of talc, 20 g of vinylacetate, and 20 g of

ethylacrylate were put into 150 g of water, and stirred for about 60 minutes.

Then, 150 g of waste paper powder was added and stirred for about 30 minutes. After completely drying the mixture at a constant temperature ranging from 120

°C to 150 °C for about 6 hours, the mixture was placed under a Hammer Mill to

be ground, and it was ground enough to be passed totally through a 10 mesh

sieve. Then, 5 g of an aliphatic polyester(manufactured by Irae Chemical Corp.; Enpol) was added. The added mixture was then injected into a

conventional injection molding machine to be subject to the injection molding process at a temperature ranging from 120 °C to 160 °C.

The bending strength of the above injection molded product was 40

MPa.

In order to determine the period of decomposition of the injection

molded product according to the present invention, the injection molded product

was soaked in water. After 10 days, the injection molded product was

completely dissolved.

The injection molded product was mixed and stirred with soil and left at room temperature. As a result, decomposition was complete in 2 to 3 months

which is far faster than the period of decomposition of the conventional wooden

golf tee, which is 2 to 3 years.

Example 2

50 g of tapioca starch was put into 150 g of water and stirred for 60

minutes. The stirred resultant was then added to 150 g of waste paper powder,

and stirred for about 30 minutes.

After completely drying the mixture at a constant temperature ranging from 120°C to 150 °C for about 6 hours, the mixture was placed under a

Hammer Mill to be ground, and it was completely ground enough to be passed totally through a 10 mesh sieve.

30 g of an aliphatic polyester(manufactured by Irae Chemical Corp.;

Enpol) was added. The added mixture was then injected into a conventional

injection molding machine to be subject to the injection molding process at a temperature ranging from 120 °C to 160 °C.

The bending strength of the above injection molded product was 20

MPa.

In order to determine the period of decomposition of the injection

molded product according to the present invention, the injection molded product

was soaked in water. After 10 days, the injection molded product completely

dissolved.

which is far faster than the period of decomposition of the conventional wooden

golf tee, which is 2 to 3 years.

As described above, since the injection molded product comprising

paper or pulp is far stronger than conventional wood, it can prove to be an

alternate material to the conventional plastic injection molded product. In

addition, since the injection molded product has good decomposability, it can

be used in place of the conventional styrene foam, in packaging products, and so on.

Furthermore, the injection molded product according to the present invention is made mainly from paper or pulp and thus possess good

decomposability that is easily dissolved in water. In addition, since waste paper can be used instead of paper or pulp, it is very economical. Finally, mass-

production using the injection molding process is also economical, as the

injection molded product possess good molding properties.

While the present invention has been described in detail with reference

to the preferred embodiments, those skilled in the art will appreciate that

various modifications and substitutions can be made thereto without departing

from the spirit and scope of the present invention as set forth in the appended

claims.

Claims

WHAT IS CLAIMED IS:

1. An injection molding composition containing paper or pulp

comprising:

a) paper or pulp;

b) an aliphatic polyester represented by the Chemical Formula 1 ; and

c) starch

[Chemical Formula 1]

wherein,

Ri and R₂ are respectively substituted or non-substituted linear

or branched Ci-C_ao alkyl; and n is the degree of polymerization ranging from 3 to 20,000. 2. The injection molding composition according to claim 1 , wherein the

composition further comprises d) one or more kinds of inorganic fillers. 3. The injection molding composition according to claim 1 or 2, wherein

the composition further comprises e) one or more acrylate derivatives

represented by the following Chemical Formula 2:

[Chemical Formula 2]

wherein,

R₃ is hydrogen or substituted or non-substituted linear or

branched Ci-Cio alkyl,

R₄ is hydrogen or methyl, and

m is the degree of polymerization ranging from 3 to 20,000.

4. The injection molding composition according to claim 1 comprising:

a) 100 weight parts of paper or pulp;

b) 2 to 70 weight parts of an aliphatic polyester; and c) 2 to 50 weight parts of starch;

5. The injection molding composition according to claim 2, wherein the

amount of the d) inorganic filler is 2 to 20 weight parts.

6. The injection molding composition according to claim 2, wherein the

d) inorganic filler is selected from a group consisting of calcium carbonate, talc,

titanium dioxide, silica powder, wollastonite, clay and a mixture thereof.

7. The injection molding composition according to claim 3, wherein the

amount of the e) acrylate derivative is 2 to 70 weight parts.

8. The injection molding composition according to claim 3, wherein the e) acrylate derivative is vinylacetate or ethylacrylate.

9. The injection molding composition according to claim 1 , wherein the

a) paper is waste paper.

10. The injection molding composition according to claim 1 , wherein the

c) starch is selected from a group consisting of wheat, potato, tapioca, corn and

a mixture thereof.

11. A method for preparing an injection molded product containing

paper or pulp comprising the steps of:

a) adding paper or pulp and starch into water, and mixing them;

b) drying the mixture of step a); c) grinding the dried mixture of step b); d) adding aliphatic polyester represented by the following Chemical

Formula 1 to the ground mixture of c), and mixing them; and e) introducing the mixture of d) into an injection molding machine and

injection molding the mixture:

[Chemical Formula 1]

wherein,

Ri and R₂ are respectively substituted or non-substituted linear

or branched Ci~C₂₀ alkyl, and

n is the degree of polymerization ranging from 3 to 20,000.

12. The method according to claim 11 , wherein in step a), one or more

kinds of inorganic fillers are further added and mixed.

13. The method according to either claim 11 or claim 12, wherein in

step a), one or more compounds represented by the following Chemical

Formula 2 are further added and mixed:

[Chemical Formula 2]

wherein, R₃ is hydrogen; substituted or non-substituted linear or

branched Ci~C₁₀ alkyl, R₄ is hydrogen or methyl, and

m is the degree of polymerization ranging from 3 to 20,000.

14. The method according to claim 11 , wherein the particle size of the

ground mixture of step c) is 10 mesh or less.

15. The method according to claim 10, wherein the injection molding of

step e) is performed at a temperature of 120 °C to 160 °C.