KR20180121301A - Method for manufacturing eco-friendly cellulose acetate compound - Google Patents

Abstract

A method for manufacturing an eco-friendly cellulose acetate compound according to the present invention includes: a process of adding a plasticizer and an additive to cellulose acetate to produce a cellulose acetate composition; and a process of molding pellets by using the cellulose acetate composition. An object of the present invention is to provide a method for manufacturing a cellulose acetate compound which does not generate toxic gas or the like by replacing a conventional phthalate plasticizer having toxicity.

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing an eco-friendly cellulose acetate compound,

The present invention relates to a process for preparing a cellulose acetate compound, and more particularly, to a process for producing an environmentally friendly cellulose acetate compound without adding a phthalate plasticizer.

Cellulose acetate (CA) is made of cellulose, which is a natural material extracted from unfolded or cotton. It has excellent regeneration and biodegradability. It is not harmful to the human body and can produce various patterns. It is a soft, high-quality natural material that is not broken and is being applied in various products along with fashion products such as eyeglass frames and accessories.

Cellulose acetate shows a certain degree of thermal formation due to the blockade of hydroxyl groups compared to cellulose, but the use of plasticizers for melt extrusion due to the strong hydrogen bonding between the rigid molecular chains inherent in the main chain and the molecular chains due to the remaining hydroxy groups It is inevitable. Generally, the method of forming cellulose acetate is disadvantageous in that it is difficult to reuse the solvent by a solution extraction method using a solvent, so that the environmental load is large and the productivity is low.

To overcome this disadvantage, the Drzal group of Michigan State University used glass transition temperature (Tg) of cellulose acetate as a plasticizer using dibutyl phthalate (DBP), diethyl phthalate (DEP), dibutyl sebacate (DBS) Tg), which is the most commonly used method.

Because of these properties, the cellulose acetate product is generally softened using a plasticizer to prepare a blend containing various additives and pigments, and then used as a method of forming a desired product by primary molding in various sheet form. The plasticizers used here are used for the purpose of increasing flexibility, workability and expandability of CA. Although there are various kinds of plasticizers, more than 80% of products use phthalate plasticizers. The phthalate plasticizers used in CA are a kind of environmental hormones harmful to humans and the environment, and they are currently being restricted in use all over the world. It is necessary to study eco-friendly CA composition and processing / molding technology to relax these regulations and to soften the intermolecular attraction of CA to give flexibility.

In the process of producing the CA sheet by press, the process of mixing the plasticizer is complicated, and most of the process must be performed by hand, so that the efficiency is lowered and it is difficult to manufacture a product having the same shape. In the case of the sheet produced by the extrusion method, the process was somewhat improved. There is a problem that not only the working environment is weak due to toxic gas generated during the work, but also only sheets of one color or multicolor layer can be manufactured. In addition, these two processes have a factor that hinders the worker's safety due to the hazardous environment caused by the gas generated by the vaporization of the phthalate plasticizer.

It should be understood that the foregoing description of the background art is merely for the purpose of promoting an understanding of the background of the present invention and is not to be construed as adhering to the prior art already known to those skilled in the art.

It is an object of the present invention to provide a cellulose acetate compound which can produce a sheet material suitable for an injection process without toxic gas or the like in place of a conventional phthalate plasticizer having toxicity, And a method for producing the same.

In order to accomplish the above object, a method for producing a cellulose acetate compound according to an embodiment of the present invention includes the steps of preparing a cellulose acetate composition by adding a plasticizer and an additive to cellulose acetate, and preparing the cellulose acetate composition into a pellet form .

And drying the cellulose acetate to lower the moisture content of the cellulose acetate before the plasticizer and the additive are added.

The plasticizer may include at least one selected from glycol-based, adipate-based, phosphate-based, polyester-based and adipic acid polyester-based plasticizers.

The content of the plasticizer may be 10 to 40 parts by weight based on 100 parts by weight of the cellulose acetate.

The viscosity of the plasticizer may range from 16 to 300 cps.

The additive may include at least one selected from heat stabilizers, processing aids, lubricants, fillers, pigments, and viscosity modifiers.

The content of the additive is preferably 0.5 to 1.5 parts by weight of a heat stabilizer, 1 to 3 parts by weight of a processing aid, 0.5 to 3 parts by weight of a lubricant, 5 to 10 parts by weight of a filler, 0.01 to 0.5 parts by weight of a pigment, And 5 to 10 parts by weight of a viscosity adjusting agent.

The viscosity modifier may be lactic acid or acrylic oligomer as a viscosity modifier.

The process for producing the pellet may be performed by melt mixing, extruding, and then cutting through an extruder.

The die temperature of the extruder may range from 210 to 220 ° C, and the rotation speed of the extruder screw may range from 250 to 300 RPM.

The L / D value of the extruder may be 20 or less.

The method for producing a cellulose acetate compound according to the present invention has the following effects.

First, since the processability can be secured while reducing the content of the phthalate plasticizer that generates the environmental hormone, an injection plate for manufacturing an eyeglass frame, etc. used for a human body can be manufactured.

Second, the vaporization of the plasticizer generated during the manufacturing process can be minimized and the deterioration factor due to overheating can be reduced by increasing the deterioration temperature rather than the melting point.

Third, additives such as a heat stabilizer, a processing aid, a lubricant, a filler, a pigment, and a viscosity adjuster can be used not only for the addition of a simple plasticizer but also for improving stability, workability, productivity and the like.

Fourth, by using the injection process, the post-processing of the plate material is unnecessary, and the waste of the material can be reduced, so that the productivity can be improved.

1 is a process diagram of a method for producing a cellulose acetate compound according to an embodiment of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms as used herein include plural forms as long as the phrases do not expressly express the opposite meaning thereto. Means that a particular feature, region, integer, step, operation, element and / or component is specified, and that other specific features, regions, integers, steps, operations, elements, components, and / And the like.

Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Commonly used predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

Hereinafter, a method for producing a cellulose acetate compound according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a process diagram of a method for producing a cellulose acetate compound according to an embodiment of the present invention. Referring to FIG. 1, a method for producing a cellulose acetate compound according to an embodiment of the present invention includes a cellulose acetate composition preparation step (S10) and a pellet processing step (S20).

A plasticizer and an additive are mixed with cellulose acetate to prepare a cellulose acetate composition (S20).

First, cellulose acetate is prepared. It is preferable that the cellulose acetate is in powder form to remove water. Moisture removal can typically be removed at a temperature below the processing temperature in a drying oven. If the drying is insufficient during the extrusion operation in the future, water vapor will be generated, resulting in foaming phenomenon, and the powder may adhere to the inside of the hopper, resulting in a problem that the raw material is not properly supplied. Therefore, it is preferable to dry the cellulose acetate at 80 DEG C for about 1 hour.

Prepared cellulose acetate has a high melting temperature due to intramolecular strong hydrogen bonding. In order to prevent pyrolysis of CA in the melting process, it is dissolved by using a solvent such as CS ₂ or H ₂ SO ₄ . When the non-substituted -OH group is controlled, the processability can be secured.

The cellulose acetate used in the present invention has a substituent content of about 39 to 50% by weight. As the substituent, acetyl, butyryl, and propionyl can be used. The higher the substituent content, the more flexible and elastic. For use as an injection molding material, the substitution degree should be about 1.8 or more, and a product having a molecular weight of about 50,000 to 70,000 is suitable.

The composition is prepared by mixing the necessary plasticizer and additives at room temperature for about 24 hours.

In the present invention, the cellulose acetate composition refers to a state in which cellulose acetate is mixed with a plasticizer and an additive.

Plasticizers are materials added to improve the processability of rubber or plastics while at the same time imparting flexibility to the product. The van der Waals force acts between the molecules of the polymer, and the extent of the Brownian motion of the molecule is determined according to the magnitude of the force, and the extent of the elastic bulge is determined. Therefore, plasticizers have good compatibility with rubber or plastic, and are required to have low volatility, thermal stability, low-temperature flexibility, and leakage resistance. The plasticizing efficiency is represented by the mass% of the plasticizer, which represents the elongation (100%) of the daily maintenance under a constant load.

The relationship between the structure and properties of the plasticizer is as follows: 1) the higher the molecular weight, the lower the transparency and volatility, but 2) the plasticization efficiency and flexibility are reduced. 3) Plasticizers with large polar structures such as ether groups or halogens in the phthalate structure are less flexible and have poor cold resistance. 4) They have improved solubility and excellent extractability of aliphatic solvents. 5) The higher the linearity of Alkyl Chain, the better the low temperature flexibility and plasticity. 7) The larger the distance between the ester groups (Ap / Po constant), the better the solubility and the plasticization rate. 8) Dibasic acid ester has higher solubility, compatibility, and plasticity than ester of dihydric alcohol of same chain length.

In the present invention, any one or more selected from among glycol-based, adipate-based, phosphate-based, polyester-based and adipic acid polyester-based plasticizers may be included, excluding the use of phthalate-based plasticizers that cause environmental hormones.

More preferably, it may include at least one of polyethylene glycol (PEG 300), diisononyl adipate (DINA), and adipic acid polyester (OLI-20N).

The plasticizer preferably has a flash point of 230 ° C or more, a viscosity of 16 cps or more, and a specific gravity of 0.9 to 1.2. The content of the plasticizer is preferably 10 to 40 parts by weight based on 100 parts by weight of the cellulose acetate. When the content of the plasticizer is less than 10 parts by weight, plasticization efficiency is lowered and the product may be stiff because of its low flexibility, and there is no effect of workability and lowering of the melting temperature. When the content of the plasticizer exceeds 40 parts by weight, the migration appears, and the required strength can not be achieved due to the lowering of the viscosity. Further, during the extrusion and injection molding, the liquid plasticizer is coated on the screw through the surface migration of the plasticizer, which hinders the movement of the resin, making it impossible to produce a proper composition. The viscosity of the plasticizer is preferably 16 to 300 cps. In this range, cellulose acetate can be mixed at room temperature, but when the viscosity is high, the plasticizer can be uniformly mixed without raising the temperature of the plasticizer to about 50 ° C.

Various additives may be further added to the cellulose acetate composition. The additive to be added at this time can be selected variously according to each application. For example, heat stabilizers, processing aids, lubricants, fillers, pigments and viscosity control agents may be used.

The heat stabilizer is added to suppress the chain decomposition reaction, and it is preferable to add 0.5 to 1.5 parts by weight of the heat stabilizer.

The processing aid is added so as to lower the processing temperature in order to compensate the impact strength depending on the application or to improve the workability, and it is preferable to add 1 to 3 parts by weight.

The lubricant is added in order to improve fluidity at the time of molding or to prevent sticking to the surface of the processing machine, and it is preferable to add 0.5 to 3 parts by weight of the lubricant.

The filler is added to improve cost reduction and touch feeling, and it is preferable to add 5 to 10 wt%.

The pigment is added to give the color of the injection product, and it is preferable to add 0.01 to 0.5 parts by weight of the pigment. When the addition amount is large, viscosity change of the composition may be caused and the physical properties of the final product may be changed. Therefore, it is more preferable to use less than 0.1 part by weight.

In addition to the plasticizer, the viscosity controlling agent is added to control the viscosity, and lactic acid or an acidic oligomer may be used. The viscosity adjusting agent is preferably added in an amount of 5 to 10 parts by weight. When the viscosity controlling agent is added, the processing time can be shortened and the plasticizing effect can be increased. If the addition amount of the viscosity adjusting agent is less than 5 parts by weight, the action effect thereof is insignificant. If the amount is more than 10 parts by weight, the instantaneous viscosity variation width increases and deterioration due to temperature increase during processing may occur.

The additives may be used singly or in combination of two or more, and may be added in the course of preparing a composition of cellulose acetate. The additives used can be used to improve processability, complement property, or inhibit decomposition. It is also used for the absorption rate at which the plasticizer is absorbed into the resin and for the ease of melting the composition.

The prepared cellulose acetate composition is melted and mixed and processed into pellets (S30). At this time, they may be melted and mixed by using a twin-screw extruder to be produced in the form of pellets. The die temperature of the twin-screw extruder is preferably about 210 to 220 占 폚. When the die temperature is high, discoloration may occur due to thermal decomposition of the cellulose acetate composition after passing through the extrusion die. The rotational speed of the screw is preferably 250 to 300 RPM.

Since cellulose acetate is a powder type, it may remain inside the general hopper and supply may not be constant. Therefore, it is possible to supply the raw material to the extruder screw more constantly when using the side feeder.

As the residence time of the screw becomes longer, the temperature deviation is not uniform and the transparency of the produced pellet is lowered and the color is discolored to brown when the extruder is melted. Therefore, it is necessary to control the retention time and the L / D value to prevent discoloration. The L / D value is preferably 20 or less.

The cellulose acetate compound prepared through the extruder screw is made into pellets through a cutter in the die head.

Cellulose acetate compounds made in pellet form can be molded into products through a variety of processing machines. It is also possible to form the plate material through the injector. The internal moisture content of the cellulose acetate compound pellets produced is about 0.7-1.47%. It is necessary to determine the maximum moisture content by comparing the moisture content reduced by drying with the appearance of the actual injection molding. In order to secure the injection molding property, it is necessary to control the water content in the cellulose acetate compound to be 0.5% or less.

The present invention will be described in more detail by way of examples. To evaluate the processing characteristics of the cellulose acetate composition, the CA compound was prepared in the form of pellets through an extruder

[Example 1]

In Example 1, 100 g of CA398-30 and 10 g of CDP were mixed and extruded at an extruder temperature (adapter-die-cylinder-screw) of 215-210-210-210 ° C, respectively, and then extruded into pellets using a cutting machine . At this time, the speed of the main screw, the speed of the feeder screw, and the speed of the cutting screw were 283, 21 and 8 rpm, respectively. As a result of the preparation through Example 1, it was difficult to control the speed per screw at the beginning, and when the time to stay on the screw was prolonged, discoloration occurred with time. When no discoloration occurred, the gloss was maintained when it was relatively transparent.

[Example 2]

In Example 2, 100 g of CA398-30, 10 g of CDP, pigment and heat stabilizer (BZ-170T 2 g) were mixed and extruder temperature (adapter-die-cylinder-screw) was adjusted to 215-210-210-210 캜 After molding, pellets were prepared using a cutting machine. At this time, the speed of the main screw, the speed of the feeder screw, and the speed of the cutting screw were 290, 20 and 8 rpm, respectively. The thermal decomposition inhibition effect of the heat stabilizer was confirmed through Example 2. The extrusion characteristics were good, the stretching was possible, and the overall uniform shape was maintained.

[Example 3]

In Example 3, 100 g of CA398-30, 10 g of CDP, pigment, and viscosity adjusting agent (Lactic acid 5 g) were mixed and extruder temperature (adapter-die-cylinder-screw) was adjusted to 215-210-210-210 캜, And then pelletized using a cutting machine. At this time, the speed of the main screw, the speed of the feeder screw, and the speed of the cutting screw were 290, 20 and 10 rpm, respectively. The viscosity control effect was confirmed by adding Lactic acid as a viscosity controlling agent through Example 3. It was confirmed that the addition of lactic acid changed the viscosity and cut irregularity and die wellring occurred.

[Example 4]

In Example 4, 100 g of CA398-30 and 10 g of PEG 300 were mixed and extruded at an extruder temperature (adapter-die-cylinder-screw) of 215-210-210-210 ° C, and then extruded using a cutting machine to prepare pellets Respectively. At this time, the speed of the main screw, the speed of the feeder screw, and the speed of the cutting screw were 290, 19, and 11 rpm, respectively. Through Example 4, the PEG plasticizing effect was confirmed. Extrusion characteristics were excellent, transparency was the best among formulations, and gloss was maintained.

[Example 5]

In Example 5, 100 g of CA398-30, 7 g of PEG 300, 7 g of CDP and 2 g of heat stabilizer (BP-50NE) were mixed and extruder temperature (adapter-die-cylinder-screw) was adjusted to 210-205-205-205 ° C Extruded, and then molded into pellets using a cutting machine. At this time, the speed of the main screw, the speed of the feeder screw, and the speed of the cutting screw were 300, 19 and 12 rpm, respectively. Through Example 5, properties of the composite plasticizer were evaluated. Discoloration occurred, but processing was good, and the product was confirmed to be broken without breakage.

[Example 6]

In Example 6, 100 g of CA398-30, 7 g of PEG 300, 1 g of a heat stabilizer (BZ-170T) and 3 g of a viscosity adjusting agent (Lactic acid) were mixed and extruder temperature (adapter- Extruded at 205-205 ° C, and then molded into pellets using a cutting machine. At this time, the speed of the main screw, the speed of the feeder screw, and the speed of the cutting screw were 300 rpm, 19 rpm and 10 rpm, respectively. Through Example 6, viscosity control effect was confirmed by adding Lactic acid as a viscosity controlling agent. Lactic acid resulted in viscosity difference, and mixing of plasticizer and additive was somewhat uneven and partial color difference was observed.

[Example 7]

In Example 7, 100 g of CA398-30, 5 g of PEG 300 and 5 g of a viscosity modifier (acrylic oligomer) were mixed and extruded at an extruder temperature (adapter-die-cylinder-screw) of 210-205-205-205 ° C Using a post-cutter. At this time, the speed of the main screw, the speed of the feeder screw, and the speed of the cutting screw were 300, 19 and 8 rpm, respectively. Through Example 6, the plasticizing effect and the workability improving effect of the acrylic oligomer were confirmed. The acrylic oligomer was used for the volatilization, but the color difference of the pellet occurred due to the partial concentration difference during the primary mixing due to the viscosity difference.

[Embodiment 8]

In Example 8, 100 g of CAP482-20 and 100 g of DINA were mixed and extruded at an extruder temperature (adapter-die-cylinder-screw) of 200-200-190-180 ° C, respectively, and then extruded into pellets using a cutting machine . At this time, the speed of the main screw, the speed of the feeder screw, and the speed of the cutting screw were 235 to 240, 19 and 15 rpm, respectively. Through Example 8, the cellulose acetate was changed to confirm whether or not the processability was improved. The melting temperature was lower than that of CA, and the pellets were stably produced. The transparency was excellent and the gloss was excellent. Although the extrusion characteristics are comparatively excellent, the composition ratio of the initial extrudate is expected to be stabilized.

[Example 9]

In Example 9, 100 g of CAP482-20 and 10 g of OLI-20N were mixed and extruded at an extruder temperature (adapter-die-cylinder-screw) of 200-200-190-180 ° C, and then extruded into pellets using a cutting machine . At this time, the speed of the main screw, the speed of the feeder screw, and the speed of the cutting screw were 235 to 240, 19 and 15 rpm, respectively. Through the example 9, the plasticizer was changed in order to maximize the plasticizing effect, and it was confirmed whether or not the workability was improved. Excellent extrusion characteristics, excellent transparency and gloss. Due to the viscosity of the plasticizer, the primary mixing is somewhat difficult, and the viscosity is controlled by heating the plasticizer so that the dispersibility in the primary mixing is increased.

As described above, in the present invention, the plasticizer and the additive are used to lower the melting point, and the cellulose acetate compound having the injection moldability can be produced by controlling the retention time and the melting temperature. Through which it can be used for the production of injection sheets and eyeglass products.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention .

Claims (11)

A step of adding a plasticizer and an additive to cellulose acetate to prepare a cellulose acetate composition; And
Preparing the cellulose acetate composition in the form of pellets;
≪ / RTI > by weight of the cellulose acetate compound.
The method according to claim 1,
And drying the cellulose acetate compound to lower the moisture content of the cellulose acetate before adding the plasticizer and the additive.
The method according to claim 1,
Wherein the plasticizer comprises at least one selected from the group consisting of glycol, adipate, phosphate, polyester and adipic acid polyester plasticizers.
The method of claim 3,
Wherein the content of the plasticizer is 10 to 40 parts by weight based on 100 parts by weight of the cellulose acetate.
The method of claim 3,
Wherein the viscosity of the plasticizer is 16 to 300 cps.
The method of claim 3,
Wherein the additive comprises at least one selected from the group consisting of heat stabilizers, processing aids, lubricants, fillers, pigments, and viscosity modifiers.
The method of claim 6,
The content of the additive is preferably 0.5 to 1.5 parts by weight of a heat stabilizer, 1 to 3 parts by weight of a processing aid, 0.5 to 3 parts by weight of a lubricant, 5 to 10 parts by weight of a filler, 0.01 to 0.5 parts by weight of a pigment, And 5 to 10 parts by weight of a viscosity controlling agent.
The method of claim 6,
Wherein the viscosity modifier is lactic acid or an acrylic oligomer as a viscosity controlling agent.
The method according to claim 1,
Wherein the step of preparing the pellet is performed by melt mixing and extruding through an extruder, followed by cutting the cellulose acetate compound.
The method of claim 9,
Wherein the die temperature of the extruder is in the range of 210 to 220 ° C, and the rotation speed of the extruder screw is in the range of 250 to 300 RPM.
The method of claim 9,
Wherein the L / D value of the extruder is 20 or less. ≪ RTI ID = 0.0 > 21. < / RTI >

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