JPS5915922B2 - Production method of thermoplastic cellulose ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the production of thermoplastic cellulose ester, and an object of the present invention is to provide a method for producing cellulose ester that has excellent thermoplasticity and practical mechanical strength.

First, the terms MS and DS used in the present invention will be explained.

In the present invention, MS is the average number of molecules of modifier bound per anhydroglucose unit constituting cellulose.

In the present invention, DS means the average number of 0-substituted hydroxyl groups among the three hydroxyl groups including the hydroxyl group generated by binding of a modifier per anhydroglucose unit constituting cellulose.

Cellulose is a natural polymer that exists abundantly in nature, and unlike oil and coal, it is a universal resource that can be reproduced, so the use of cellulose as a raw material for plastics is highly desirable from a resource standpoint. In addition, cellulose is strong and has an excellent feel, and like cellophane, it has good transparency and gloss, and has excellent properties. There are also high expectations.

However, cellulose itself lacks thermoplasticity and cannot be turned into plastic.

In order to use cellulose as a plastic, it is necessary to replace at least a portion of the hydroxyl groups it contains,5 and cellulose derivatives that have already been put into practical use as plastics include, for example, cellulose acetate, cellulose acetate propionate, etc. nate, cellulose acetate butyrate, and ethyl cellulose.

(2) These existing cellulose-based plastics generally exhibit excellent properties such as toughness, transparency, gloss, feel, and weather resistance, but on the other hand, they lack thermoplasticity and require a considerable amount of plasticizer for molding.

For example, cellulose acetate does not exhibit the necessary thermoplasticity for processing in the absence of a plasticizer and cannot be processed into molding. However, in general, the presence of plasticizers is unfavorable from a physical standpoint, and some plasticizers are questionable from a safety standpoint.If possible, it is best not to use plasticizers or to use a small amount of plasticizers. It is hoped that cellulose-based plastics that can be molded will emerge.

Benzylcellulose has been known as a cellulose derivative that has sufficient thermoplasticity without the use of plasticizers, but it has poor weather resistance and has not been put to practical use. M.S.
Hydroxypropyl cellulose, which has a . - Generally, when used in molding materials, films, coating materials, etc., it is necessary not only to have thermoplastic properties but also to have excellent mechanical properties. Through intensive research, we have arrived at the present invention.

That is, the present invention is directed to modified cellulose which is modified by addition of an epoxy compound and whose amount is 0.1 MS × 2 as the average number of molecules of the epoxy compound bound per anhydroglucose unit constituting the cellulose. by esterifying with at least one type of lower saturated organic acid or its acid anhydride or acid chloride, the degree of ester substitution DS (sum of 5 MS is 1.5 and DS + MS < 5). This is a method for producing cellulose ester.According to the present invention, a cellulose ester that has excellent thermoplasticity and has practical mechanical strength can be obtained.

The starting material used in the present invention has an MS of 0.1 M
It is a modified cellulose that is Sku2.

Here, modified cellulose refers to cellulose modified by addition of an epoxy compound, and other groups may be bonded to the cellulose residue. These modified celluloses are easily produced by treating cellulose or a cellulose derivative with the following epoxy compound as a modifying agent according to a known method.

Epoxy compounds used in the present invention include monoepoxy compounds such as ethylene oxide, propylene oxide, butylene oxide, epoxy alkanes, styrene oxide, cyclohexene monooxide, epichlorohydrin, butyl glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, and cresyl. Examples include glycidyl ether, glycidyl metatarylate, glycidyl acrylate, eboxidized soybean oil, eboxidized linseed oil, and epoxy stearate.

Modified cellulose can be obtained by allowing these to act on cellulose or cellulose derivatives. The degree of modification of the modified cellulose used in the present invention, that is, M
S is 0.1 MS<2, particularly preferably 0.2
It is MS〈2.

In general, the smaller the MS, the smaller the amount of modifier required during modified cellulose production, which is economical, but MS<0
．． In No. 1, the thermoplasticization effect due to esterification is not significant.

When MS>0.1, the thermoplasticization effect due to esterification becomes remarkable, and especially when MS>0.2, it is remarkable. Also, MS〉2
However, although the thermoplasticization effect due to esterification is remarkable, on the other hand, the mechanical strength decreases, making it impractical.

To explain in more detail, cellulose itself lacks thermoplasticity, and the modified cellulose used in the present invention with an MS of 0.1<MS>2 also lacks thermoplasticity or has very little thermoplasticity. be.

For example, even hydroxypropylcellulose, which is known to have good thermoplasticity among hydroxyalkylcelluloses, is known to be thermoplastic with an MS of about 3 or more; It has poor thermoplasticity. On the other hand, even if cellulose is simply esterified, the thermoplasticization effect is small; for example, cellulose acetate (acetyl DS 2.4, degree of polymerization 150) in the absence of a plasticizer at 230°C and under a load of 51<g. Melt index (according to ASTM D1238-57T).

(hereinafter abbreviated as MI) is O and does not exhibit thermoplasticity. However, the present inventors have found that thermoplasticity is dramatically improved by esterifying modified cellulose with an MS of 0.1 or more, and when using modified cellulose with an MS of 2 or less, it is not practical. It was discovered that it has mechanical strength, leading to the present invention.

The remarkable thermoplasticization effect, which is a feature of the present invention, can only be obtained by esterifying modified cellulose, and conversely cannot be obtained when cellulose ester is modified with an epoxy compound. , M.S. and D.
Even if S is the same, the cellulose ester modified with an epoxy compound has
Its thermoplasticity is very small.

US Pat. No. 2,828,305 discloses a method for modifying cellulose esters with epoxy compounds, but this method is unsuitable for obtaining thermoplastic products.

Further, US Pat. No. 3,824,085 discloses that hydroxypropylcellulose is acetylated or laurylated and used as a gluing agent for organic solvents.

However, in this case, since hydroxypropylcellulose with an MS of 2 to 8 is used as a raw material, the mechanical strength of the resulting product is significantly low with such a high MS, and it is difficult to use for general purpose materials such as plastics and coating agents. It is not suitable for this purpose. Next, esterification will be explained.

The ester group introduced by esterification is an ester consisting of one or more organic acids, and may further be partially esterified with an inorganic acid.

However, polybasic acid esterification as disclosed in Japanese Patent Publication Nos. 48-19391 and 19552 is not preferred because it causes crosslinking of the product and also results in poor water resistance.

Particularly preferred are esters of one or more of lower saturated organic acids, such as acetic acid, propionic acid, butyric acid, and the like.

Higher saturated organic acids or unsaturated organic acids may be introduced for purposes such as coating agents or other special uses.

In short, an appropriate ester group may be selected depending on the properties of the desired product. The DS of the esterified product can be changed arbitrarily depending on the reaction conditions within the range of O<DS.

From the viewpoint of thermoplasticity, the preferred range of DS is 1.5 MS + DS, particularly 1.5 MS + DS 5, although it is not possible to specify the range of DS alone because the thermoplasticity of the product is dominated by both MS (5 DS). .7〈MS+DS〉5 is preferred.

MS+DS〈1.5 has poor thermoplasticity, and MS+DS
>5, the mechanical strength decreases.

As the esterification method, a method generally used for esterification of cellulose and cellulose derivatives can be used, and no special method is required.

Note that during esterification, the MS of the modified cellulose is usually maintained unchanged. According to the present invention, cellulose can be easily and widely thermoplasticized using common industrially available raw materials, has practical mechanical properties, and has a plasticizer added thereto. It is possible to obtain thermoplastic products that can be molded without molding.

Currently, questions are being raised about some plasticizers from safety concerns.
This is of great significance, and the present invention opens up a new way to utilize cellulose as a plastic. Of course,
Naturally, the molding conditions can be relaxed by adding a small amount of plasticizer. Hereinafter, specific examples of the present invention will be explained with reference to Examples.

Reference Example 1 Synthesis of cellulose acetate modified with epoxy compound (modifier: phenyl glycidyl ether) Cellulose acetate (acetyl group DSl.9Ol [η] 1.17
, 30 groups C) 409 in acetone in 600 ml of dioxane
Phenyl glycidyl ether 1209 and boron trifluoride etherate 49 were added, and the mixture was reacted at room temperature for 5 hours.

Precipitate with a large amount of methanol, separate by filtration,
After washing and drying, a product (acetyl group DSL 49, phenyl glycidyl ether MSO 32) was obtained. The analysis of acetyl group DS was conducted according to ASTM D871-63 (the same applies to the following examples). In addition, for phenyl glycidyl ether MS, dissolve the product in a methylene chloride rimethanol mixed solvent (9:1), and
μ) Measured from absorption. Example 1 Acetylation of the product of Reference Example 1 Acetic acid 5409 was added to the product 309 of Reference Example 1 and heated to 70 to 80'G with stirring to dissolve it.

Thereafter, the mixture was cooled to room temperature, and acetic anhydride 9,69 was added thereto, and while stirring vigorously, 3 ml of a solution of 7001) perchloric acid diluted 10 times with acetic acid was added, and the mixture was reacted for 30 minutes at room temperature. The product is precipitated with a large amount of methanol, filtered, washed, and dried to obtain the acetylated product (acetylated DS2.O6, phenyl glycidyl ether MSO.3l, [η]1.1
0) was obtained. M was measured as an index of thermoplasticity, and the results are shown in Table 1.

Comparative Example 1 MS and DS are almost the same as in Example 1, but the order is reversed, and the esterified product is modified with an epoxy compound.

Cellulose acetate (acetyl group DS2.48, [η
] 1.14, 30℃ in acetone) 30f1 was dissolved in dioxane 400ml, phenyl glycidyl ether 1
009 and boron trifluoride etherate 49 were added and reacted at room temperature for 24 hours.

Isolation, production, and drying of the product were carried out in the same manner as in Example 1, and the product (acetylated DS 2.1O, phenyl glycidyl ether MSO
．． 33, [η] 1.06) was obtained.

M is shown in Table 1. Comparative Example 2 Non-esterified modified cellulose (modifier: phenyl glycidyl ether) The product of Reference Example 1 was mixed with 6% Na
Saponification was performed for 24 hours using an OH aqueous solution to obtain a product.

Under these conditions, the hydroxyalkyl group remains unchanged. The MI was measured and the results compared with Example 1 are shown in Table 1. Although the products of Example 1 and Comparative Example 1 have almost the same composition, their MIs differ by more than 100 times. It was shown that the effect was very small even when cellulose ester was modified with an epoxy compound.

In addition, the thermoplastic (MI) of a simple esterified product and a modified product with an epoxy compound is Cell 4 of Reference Example 1 and Comparative Example 1.
As seen in the 0-base acetate and the PGE-modified cellulose of Comparative Example 2, even though the DS and MS were comparable to those of Example 1, they were zero. Reference example 2 Synthesis of modified cellulose (modifier: propylene oxide)
Add 70 ml of 5% NaOH aqueous solution to cellulose (degree of polymerization 150) 509, mix well, add propylene oxide 4009, keep at 0 to 5°C for 1 hour while stirring well, and then raise the temperature to 35 to 36°C. Allowed time to react.

The contents were separated by F, and a precipitate was collected. Warm water was added to the precipitate to form a suspension, which was neutralized with an aqueous phosphoric acid solution, and then dropped into acetone to precipitate a reaction product.

After separation by filtration and repeated washing three times with acetone/H2O (9:1), the product was vacuum dried at about 80°C to obtain a product (propylene oxide MSl.l). In addition, M.S.
Measurements were made in accordance with ASTM D2363-69. Example 2 Dimethylformamide 80 was added to the product 409 of Reference Example 2.
0m11 pyridine 40m11 acetyl chloride 39.
2 g was added and reacted at 100°C for 1 hour.

Thereafter, the reaction solution cooled to room temperature was added to a large amount of water to precipitate the product, which was filtered, washed with water and washed with methanol repeatedly, and then dried under vacuum at about 80°C to form the reaction product (propylene oxide MSI. l, acetyl group DS2.34,
[η] 1.10 (30°C in acetone) was obtained. The Ml is shown in Table 2.

Further, the film formed from the acetone solution had a tensile strength of 4331<9/CTil and an elongation of 9.6%. Table 2
Therefore, even if cellulose is simply hydroxypropylated, M
Sl. It can be seen that 1 is not thermoplastic, but when it is acetylated, it becomes highly thermoplastic.

Table 1 shows that simple acetylated products are not thermoplastic.
As shown. Examples 3 to 4 Acetylation was carried out in the same manner as in Example 2 using hydroxypropyl cellulose with MS of 0.8 (Example 3) and 1.8 (Example 4).

Table 3 shows the composition, MI and tensile strength of the obtained product.

Comparative Example 3 Hydroxypropylcellulose having an MS of 2.4 was acetylated in the same manner as in Example 2.

Table 3 shows the composition, MI and tensile strength of the obtained product. It has high thermoplasticity but low tensile strength.

Reference Example 3 Synthesis of modified cellulose (modifying agent: styrene oxide) 50 g of cellulose (degree of polymerization 400) was mixed with 18% N
After being immersed in an aOH aqueous solution at 20° C. for 4 hours, it was pressed to obtain 1509, which was charged into an autoclave with styrene oxide 6009, heated to 100° C., and reacted for 6 hours.

After the reaction was completed, the product was separated by filtration, washed successively with benzene, methanol, and water, and then dried under vacuum at about 80°C to obtain a product. Example 5 Mixed esterification (acetylation/propionylation) of the product of Reference Example 3 After adding acetic acid 409 to the product 409 of Reference Example 3 and keeping it at 30°C for 1 hour, propionic acid 409, propionic anhydride 1609 and 3.2 f1 of sulfuric acid was added and reacted at 35 to 40°C for 4 hours.

After neutralizing the sulfuric acid by adding magnesium acetate, the product was poured into a large amount of water to precipitate the product.

Separated by filtration, washed with water repeatedly, washed with methanol, and dried under vacuum at about 80°C to obtain esterified products (styrene oxide MSO.26, acetyl group DSO.23).
, propionyl group DSl. 86) was obtained. Note that styrene oxide MS was measured by dissolving the product in a methylene chloride rimethanol mixed solvent (9:1) and measuring ultraviolet absorption (258 mμ). Furthermore, acetyl group DS and propionyl group DS were measured according to ASTM D817. MI(23
0° C., load 5 kg) was 41.

Incidentally, the MI of the product of Reference Example 3 was O. Example
Dimethylformamide 600Tn1 to 6MS1.4 hydroxypropyl cellulose 409! , pyridine 20m
1. Add stearyl chloride 149 and react at 100°C for 1 hour to form an esterified product (propylene oxide MSl.
4. Stearyl DSO. 2) was obtained.

Claims (1)

[Claims] 1. Modified cellulose is modified by adding an epoxy compound, and the amount of the added amount is 0.1<MS<2 as the average number of molecules of epoxy compounds bound per anhydroglucose unit constituting the cellulose. By esterifying with at least one type of acid, its acid anhydride, or acid chloride, the degree of ester substitution DS and MS
A method for producing a thermoplastic cellulose ester, characterized in that the sum of 1.5<DS+MS<5.