JP7806783B2 - Resin composition, hot melt molded product, and molding method - Google Patents

Description

The present invention relates to a resin composition, a hot-melt molded product, and a molding method. More specifically, the present invention relates to a resin composition containing a cellulose resin that has excellent hot-melt moldability and is capable of retaining the good physical properties of the cellulose resin in the resulting hot-melt molded product, a hot-melt molded product, and a molding method.

Cellulose resins have been used for a long time, and because of the abundance of biological resources available as raw materials, they are considered promising biomass resins. However, cellulose resins are generally highly crystalline, which means that their thermal decomposition temperature and melting point are close to each other. Furthermore, their low melt fluidity makes them poorly thermoformable, making them difficult to use for modern mass-produced objects using manufacturing methods such as injection molding.

For example, triacetyl cellulose (generally with a degree of substitution of about 2.9), a type of cellulose ester that excels in optical properties and heat resistance among cellulose resins, is highly crystalline and has a melting point of around 300°C, which is close to the decomposition temperature of the cellulose skeleton. Therefore, when used in thermoforming, partial thermal decomposition causes discoloration of the resin and a decrease in molecular weight, making it essentially unusable as a thermoplastic resin.

To address this issue, triacetyl cellulose has been hydrolyzed to a degree of substitution of around 2.5, reducing its crystallinity, and a thermoplastic grade has been commercialized by adding a large amount of plasticizer. However, the large number of hydroxyl groups causes problems with moisture absorption and expansion/contraction due to changes in humidity, and the addition of plasticizers also reduces the excellent physical properties of cellulose resins, such as mechanical strength.

For example, Patent Document 1 describes a method in which a resin composition containing a specific compound having a fluorene skeleton as a plasticizer and a specific amount of a stabilizer is used for cellulose ester, and the melt-kneading temperature is lowered to 240-290°C to pelletize the resin composition, followed by injection molding. However, the method described in Patent Document 1 does not sufficiently lower the temperature during molding of the resin composition, and further improvements are needed in terms of moldability and the physical properties of the resulting molded product.

JP 2015-86254 A

The present invention was made in consideration of the above problems and circumstances, and its objective is to provide a resin composition containing a cellulose resin that has excellent hot-melt moldability and is capable of retaining the good physical properties of the cellulose resin in the resulting hot-melt molded product. It also aims to provide a hot-melt molded product that retains the good physical properties of the cellulose resin, and a molding method for the same.

In order to solve the above-mentioned problems, the inventors, in the course of investigating the causes of the above-mentioned problems, discovered that by using an additive, in a mixture obtained by adding 10 parts by mass of additive to 90 parts by mass of crystalline cellulose resin, together with crystalline cellulose resin, a resin composition can be obtained which has excellent hot-melt moldability and is able to retain the good physical properties of the cellulose resin in the resulting hot-melt molded product, and thus arrived at the present invention.
That is, the above-mentioned problems of the present invention are solved by the following means.

1. A resin composition for hot melt molding containing a crystalline cellulose resin as a main component,
Contains an additive that satisfies the following formula (1):
the additive is any one of the following compounds RAa-1, RAa -9, and RB-3,
The resin composition is characterized in that the crystalline cellulose resin is a crystalline cellulose ester resin, in which the degree of substitution of hydrogen atoms for hydroxy groups in the crystalline cellulose ester resin is 2.7 or more, and the degree of substitution of acetyl groups in the crystalline cellulose ester resin is 2.7 or more.
Formula (1) T2≦T1×0.93
In formula (1), T2 represents the melting point [°C] of a mixture in which 10 parts by mass of the additive is added to 90 parts by mass of the crystalline cellulose resin, and T1 represents the melting point [°C] of the crystalline cellulose resin alone.

2. The resin composition according to item 1, wherein the difference between T1 and T2 is 25°C or more.

3. The resin composition according to item 1 or 2, wherein the additive satisfies the following (i), (ii), or (iii) in the following formula ( 2 ):
(i) Vu/V1<1.0 and χ<3
(ii) 1.0≦Vu/V1<1.5 and χ<6
(iii) 1.5≦Vu/V1 and χ<8
Formula (2) 1/Tm-1/Tm ⁰ = (R/△Hu)×(Vu/V1)×(ν ₁ −χν ₁ ² )
In formula (2), the symbols have the following meanings.
Tm: melting point (absolute temperature) of a mixture obtained by adding 10 parts by mass of the additive to 90 parts by mass of the crystalline cellulose resin
Tm ⁰ : melting point (absolute temperature) of the crystalline cellulose resin alone
R: gas constant ΔHu: heat of fusion per mole of repeating unit forming the crystalline cellulose resin V1: molar volume of the additive Vu: molar volume of repeating unit forming the crystalline cellulose resin ν ₁ : volume fraction of the additive in a mixture obtained by adding 10 parts by mass of the additive to 90 parts by mass of the crystalline cellulose resin χ: parameter indicating the interaction between the crystalline cellulose resin and the additive

4. A hot melt molded article of the resin composition according to any one of items 1 to 3 .

5. A molding method for hot melt molding the resin composition according to any one of items 1 to 3 , comprising:
The molding method comprises carrying out the hot melt molding under conditions that satisfy the following formula (3):
Formula (3) T3≦T1×0.75+20
In formula (3), T3 represents the maximum temperature [°C] of the resin composition during hot melt molding.

6. The molding method according to item 5 , which is injection molding, extrusion molding, or fused deposition modeling.

The above-mentioned means of the present invention make it possible to provide a resin composition containing a cellulose resin that has excellent hot-melt moldability and is capable of retaining the good physical properties of the cellulose resin in the resulting hot-melt molded article. It is also possible to provide a hot-melt molded article that retains the good physical properties of the cellulose resin, and a molding method for the same. The mechanism of action or manifestation of the effects of the present invention is speculated to be as follows.

As mentioned above, improving the hot melt moldability of crystalline cellulose resin requires that the melting point of the crystalline cellulose resin be lower than its decomposition temperature and that the difference between the two be large. Decomposition reactions of cellulose derivatives include the elimination of side chains due to heating, the cleavage of glycosidic bonds, and the ring-opening and elimination reactions of pyranose rings, which are the structural units of cellulose. Since these reactions are largely dependent on the structure of the polymer material, it is difficult to achieve a high decomposition temperature by improving this process itself.

In addition, a method is known for lowering the melting point of crystalline cellulose resin by adjusting the substituents that replace the hydrogen atoms of the three hydroxyl groups present per β-glucose residue, the structural unit of cellulose, and the degree of substitution during molecular design of the crystalline cellulose resin. However, it is difficult to find a method for lowering the melting point to the desired range while maintaining productivity, physical properties, etc.

Meanwhile, a method is known in which additives such as plasticizers are added to crystalline cellulose resin to lower the melting point of the mixture of crystalline cellulose resin and the additive, thereby improving hot melt moldability. Examples of such additives in practical use include phthalate esters, trimellitate esters, glycerin, aliphatic esters of dicarboxylic acids, and phosphate esters. Also known is a compound with a fluorene skeleton, as described in Patent Document 1.

As a result of extensive research into additives to be used with crystalline cellulose resin, the inventors have discovered that by using an additive that satisfies the above formula (1), a composition containing crystalline cellulose resin and said additive has a melting point that is sufficiently lower than the decomposition temperature of the crystalline cellulose resin and has excellent hot melt moldability.

Conventionally, plasticizers used for cellulose resins consist of a strongly polar portion, such as an ester group, as mentioned above, and a relatively large non-polar portion consisting of a long-chain alkyl group. The polar portion of the plasticizer orients itself to the polar portion of the cellulose resin, and the large non-polar portion increases the spacing between the polymer chains, facilitating molecular motion of the polymer chains and lowering the glass transition temperature (Tg) and melting point.

In compositions containing a polymer compound and a plasticizer, Tg decreases in proportion to the volume fraction ratio of the polymer compound (Tg1) to the plasticizer (Tg2, where Tg1 > Tg2), whereas the decrease in melting point is small, with a melting point decrease of approximately 0.95 as defined in this invention (see definition below). It is believed that additives satisfying formula (1) according to the present invention operate using a mechanism completely different from conventional mechanisms. Furthermore, this previously unknown mechanism reduces the degree of decrease in the quality of hot-melt molded products, which normally decreases with a decrease in melting point, and enables the resulting hot-melt molded products to maintain the good physical properties of the crystalline cellulose resin.

The resin composition of the present invention is a resin composition for hot melt molding containing a crystalline cellulose resin as a main component, and is characterized by containing an additive that satisfies the above formula (1). This characteristic is a technical feature common to all of the following embodiments.

In an embodiment of the resin composition of the present invention, from the viewpoints of ease of processing and the mechanical properties of the resulting hot-melt molded product, it is preferable that the crystalline cellulose resin is a crystalline cellulose ester resin.

Furthermore, when the crystalline cellulose resin is a crystalline cellulose ester resin, it is preferable that the degree of substitution of hydrogen atoms of hydroxy groups in the crystalline cellulose ester resin is 2.7 or more, and the degree of acetyl group substitution is 2.5 or more. Furthermore, it is more preferable that the degree of acetyl group substitution of the crystalline cellulose ester resin is 2.7 or more.

The "degree of substitution of hydrogen atoms of hydroxy groups" in a crystalline cellulose ester resin refers to the number of esterified hydroxy groups, three in number per cellulose structural unit, or in other words, the average number of hydroxy group hydrogen atoms substituted with acyl groups for the entire resin, and is expressed as a value between 0 and 3. The "degree of substitution of hydrogen atoms of hydroxy groups" in a crystalline cellulose ester resin is also referred to as the "degree of acyl group substitution." When two or more types of acyl groups substitute hydrogen atoms in a crystalline cellulose ester resin, the sum of the degrees of substitution for each acyl group is the degree of acyl group substitution.

When the degree of substitution of acetyl groups in crystalline cellulose ester resins among the acyl groups is high, the melting point is closer to the decomposition temperature of the cellulose skeleton, and there is a strong demand for improved hot melt moldability. Therefore, when a crystalline cellulose ester resin has a degree of substitution of hydrogen atoms in hydroxyl groups, i.e., an acyl group substitution degree, of 2.7 or more and an acetyl group substitution degree of 2.5 or more, the effects of the present invention achieved by using an additive satisfying the above formula (1) are more pronounced. Furthermore, when the acetyl group substitution degree is 2.7 or more, the effects of the present invention are particularly pronounced.

In an embodiment of the resin composition of the present invention, from the viewpoint of realizing the effects of the present invention, it is preferable that the difference between T1 and T2 is 25°C or more.

In an embodiment of the resin composition of the present invention, the additive preferably satisfies the following (i), (ii), or (iii) in the above formula (2):
(i) Vu/V1<1.0 and χ<3
(ii) 1.0≦Vu/V1<1.5 and χ<6
(iii) 1.5≦Vu/V1 and χ<8

The above formula (2) is a formula described in a literature (P.J. Flory, Principles of Polymer Chemistry (1953)) based on a statistical thermodynamic interpretation by Flory, Haggins, et al. Note that in this literature, formula (2) is described as a formula that shows the relationship between polymeric materials and additives, not just the relationship between crystalline cellulose resin and additives.

In equation (2), χ is a parameter that indicates the interaction between the crystalline polymer and the additive. In principle, the above equation is derived under the assumption that there is no difference between the interactions between the repeating units that form the crystalline polymer, the interactions between additives, and the interactions between the repeating units that form the crystalline polymer and the additives. Therefore, the ideal state is for χ to be 0, but in reality, there are interactions between crystalline polymers, between additives, and between the crystalline polymer and the additives, so it often shows a value other than 0.

In the crystalline cellulose resin of the present invention, χ>0 indicates a direction in which, relative to the ideal state, the interaction between the crystalline cellulose resin and the additives is weaker than the interactions between other crystalline cellulose resins and between the additives, making mixing difficult. χ<0 indicates a direction in which, relative to the ideal state, the interaction between the crystalline cellulose resin and the additives is stronger than the interactions between other crystalline cellulose resins and between the additives, making it easier for the additive to mix into the crystalline cellulose resin.

In an embodiment of the resin composition of the present invention, the smaller the value of χ, the greater the effect of the present invention. Specifically, χ is preferably less than 8, more preferably 3 or less, and even more preferably 0 or less.

The required range of χ varies depending on the value of Vu/V1 in formula (2). In formula (2), Vu/V1 represents the ratio of the molar volume (Vu) of the repeating units forming the crystalline cellulose resin to the molar volume (V1) of the additive. When Vu/V1 is 1.0 or greater but less than 1.5, χ is preferably less than 6 (condition (ii) above); when Vu/V1 is less than 1.0, χ is preferably less than 3 (condition (i) above); and when Vu/V1 is 1.5 or greater, χ is preferably less than 8 (condition (iii) above). From the opposite perspective, a larger Vu/V1 is preferable because it broadens the range of usable χ and broadens the range of additive choices.

By satisfying condition (i), condition (ii), or condition (iii), additives tend to be more easily mixed into the crystalline cellulose resin, and it is expected that compositions containing these will have better hot-melt moldability.

In an embodiment of the resin composition of the present invention, from the viewpoint of realizing the effects of the present invention, it is preferable that the additive contains a compound having a structure represented by the above general formula RAa, general formula RAb, or general formula RB.

The hot-melt molded product of the present invention is characterized by being hot-melt molded using the resin composition of the present invention described above.

The molding method of the present invention is a molding method for hot-melt molding a resin composition, characterized in that the hot-melt molding is carried out under conditions that satisfy the above formula (3). The molding method of the present invention is preferably an injection molding method, an extrusion molding method, or a fused deposition modeling method.

The present invention, its components, and modes and aspects for implementing the present invention are described in detail below. In this application, the use of "to" means that the numerical values before and after it are included as lower and upper limits. In this specification, the terms "contain as a main component" and "consist mainly of" mean that the main component in question accounts for 50% by mass or more of the whole.

[Resin composition]
The resin composition of the present invention is a resin composition for hot melt molding containing a crystalline cellulose resin as a main component, and is characterized by containing an additive satisfying the following formula (1). Hereinafter, the additive satisfying formula (1) will also be referred to as additive (A).
Formula (1) T2≦T1×0.93
In formula (1), T2 represents the melting point [°C] of a mixture in which 10 parts by mass of the additive is added to 90 parts by mass of the crystalline cellulose resin, and T1 represents the melting point [°C] of the crystalline cellulose resin alone.

In this specification, the term "crystalline cellulose resin" is used as a general term for resins made of cellulose derivatives that have a melting point. A resin having a melting point means that it exhibits a clear endothermic peak rather than a stepwise endothermic change in differential scanning calorimetry (DSC). Specifically, a clear endothermic peak means a peak in which the half-width of the endothermic peak upon melting is within 30°C when measured in DSC, for example, at a heating rate of 10°C/min.

The melting point of the crystalline cellulose resin alone, T1 [°C], can be measured using a DSC device. Specifically, T1 is the peak temperature [°C] of the endothermic peak obtained by DSC.

The melting point T2 [°C] of a mixture (hereinafter also referred to as mixture (S)) in which 10 parts by mass of additive (A) is added to 90 parts by mass of crystalline cellulose resin can be measured using a DSC device in the same manner as above, using mixture (S) instead of crystalline cellulose resin alone.

Specifically, mixture (S) is prepared as follows: 90 parts by mass of crystalline cellulose resin is dissolved in 1,900 parts by mass of a mixed solvent of methylene chloride and methanol (mixing ratio (by mass): methylene chloride:methanol = 9:1), to which 10 parts by mass of additive (A) is added and mixed. The solvent is then removed using an evaporator, and the resulting solid is dried at 110°C, resulting in mixture (S).

The resin composition of the present invention has excellent hot-melt moldability because the relationship between the melting point T1 of the crystalline cellulose resin alone and the melting point T2 of the mixture (S) satisfies formula (1), and the resulting hot-melt molded product is able to retain the good physical properties of the cellulose resin.

The resin composition of the present invention may optionally contain other components in addition to the crystalline cellulose resin and additive (A), provided that the effects of the present invention are not impaired. Examples of other components include resins other than the crystalline cellulose resin, and additives other than additive (A). Each component contained in the resin composition of the present invention is described below.

(Crystalline cellulose resin)
The resin composition of the present invention contains a crystalline cellulose resin as a main component. The content of the crystalline cellulose resin in the resin composition of the present invention is 50% by mass or more, preferably 60% by mass or more, and more preferably 70% by mass or more. The components contained in the resin composition of the present invention are broadly classified into resins and additives. The resin may be composed of only crystalline cellulose resin, or may be composed of a combination of crystalline cellulose resin and other resins. The other resins will be described later. The proportion of the crystalline cellulose resin relative to the total amount of resin is, for example, preferably 55 to 100% by mass, more preferably 70 to 100% by mass, and more preferably 100% by mass, while maintaining the content of the crystalline cellulose resin as a main component in the resin composition.

Specific examples of crystalline cellulose resins include crystalline cellulose ester resins and crystalline cellulose ether resins. Crystalline cellulose ester resins are preferred from the standpoints of ease of processing and the mechanical properties of the resulting hot-melt molded products.

For crystalline cellulose ester resins, an acyl group substitution degree of 2.7 or higher is preferred, as it is less susceptible to the effects of moisture. The acyl group substitution degree is more preferably in the range of 2.8 to 3.0.

The acyl group in the crystalline cellulose ester resin is not particularly limited as long as it is an acyl group represented by R-C(=O)- (R is a monovalent hydrocarbon group). For example, the acyl group is preferably an acyl group in which R is an aliphatic hydrocarbon group having 1 to 5 carbon atoms. More preferred are acetyl groups in which R is a methyl group, propionyl groups in which R is an ethyl group, and butyryl groups in which R is a propyl group, with acetyl groups being particularly preferred. Furthermore, the degree of acetyl group substitution in the crystalline cellulose ester resin is preferably 2.5 or more, and more preferably 2.7 or more.

The acyl group contained in the crystalline cellulose ester resin may be of one type or two or more types. The acyl group contained in the crystalline cellulose ester resin is preferably of one type, and from the standpoint of cost and physical properties, this type is preferably an acetyl group. The degree of substitution of acyl groups in the crystalline cellulose ester resin can be measured in accordance with ASTM-D817-96.

The weight average molecular weight (Mw) of the crystalline cellulose ester resin is preferably within the range of 10×10 ³ to 1000×10 ³ , more preferably within the range of 50×10 ³ to 500×10 ^3. The number average molecular weight (Mn) of the crystalline cellulose ester resin is preferably within the range of 10×10 ³ to 1000×10 ³ , more preferably within the range of 10×10 ³ to 500×10 ^3. The ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the crystalline cellulose ester resin is preferably within the range of 1 to 5.

If the molecular weight characteristics of the crystalline cellulose ester resin are within the above range, this is preferable in terms of the hot melt moldability of the resin composition and the physical properties of the resulting hot melt molded product.

The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of crystalline cellulose ester resin can be measured, for example, using gel permeation chromatography (GPC). The measurement conditions are as follows:

Solvent: methylene chloride Column: Shodex K806, K805, K803G (manufactured by Showa Denko K.K.; three columns connected together)
Column temperature: 25°C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (GL Sciences)
Pump: L6000 (Hitachi, Ltd.)
Flow rate: 1.0 ml/min. Calibration curve: A calibration curve was prepared using 13 samples of standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) with Mw = 1,000,000 to 500. The 13 samples were used at approximately equal intervals.

Crystalline cellulose ester resins can be produced by known methods. Typically, raw cellulose is mixed with a specific organic acid (acetic acid, propionic acid, butyric acid, etc.), an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride, etc.), and a catalyst (sulfuric acid, etc.) to esterify the cellulose and allow the reaction to proceed until a cellulose triester is produced. In the triester, the three hydroxy groups of the glucose unit are replaced with an acyl acid from the organic acid. Using two types of organic acids simultaneously allows for the production of mixed ester cellulose acylates, such as cellulose acetate propionate and cellulose acetate butyrate.

Next, the cellulose triester is hydrolyzed as needed to synthesize a crystalline cellulose ester resin with the desired degree of acyl group substitution. After that, the crystalline cellulose ester resin is obtained through processes such as filtration, precipitation, washing with water, dehydration, and drying.

In the above, the raw material cellulose may be wood pulp or cotton linter, and the wood pulp may be either softwood or hardwood, but softwood is preferred. Cotton linter is preferred from the standpoint of releasability during molding. Crystalline cellulose ester resins made from these may be used alone or in appropriate mixtures.

For example, the ratios of cotton linter-derived cellulose acylate:wood pulp (coniferous)-derived cellulose acylate:wood pulp (broadleaf)-derived cellulose acylate can be 100:0:0, 90:10:0, 85:15:0, 50:50:0, 20:80:0, 10:90:0, 0:100:0, 0:0:100, 80:10:10, 85:0:15, and 40:30:30.

Furthermore, the crystalline cellulose ester resin may be, for example, a cellulose acylate produced by the above-mentioned method, in which the degree of acyl group substitution and the degree of acetyl group substitution are adjusted by mixing two or more types of cellulose acylate with different degrees of acyl group substitution.

When 1 g of the crystalline cellulose ester resin of the present invention is added to 20 ml of pure water (electrical conductivity of 0.1 μS/cm or less, pH 6.8) and stirred at 25°C for 1 hour under a nitrogen atmosphere, it is preferable that the pH is in the range of 6 to 7 and the electrical conductivity is in the range of 1 to 100 μS/cm.

The crystalline cellulose ester resin of the present invention can be synthesized by specifically referring to the methods described in JP-A-10-45804 and JP-A-2017-170881.

The crystalline cellulose ester resin used in the present invention may be a commercially available product. Examples of commercially available products include LT-35 (manufactured by Daicel Corporation), L-30 (manufactured by Daicel Corporation), CA3205 (manufactured by Eastman Corporation), and CAP482-20 (manufactured by Eastman Corporation).

(Other resins)
The resin composition of the present invention may contain, as necessary, other resins in addition to the crystalline cellulose resin, as long as the effects of the present invention are not impaired.

Other resins include, specifically, amorphous cellulose resin, polyolefin resin, polystyrene resin, polyamide resin, polyimide resin, polyester resin, acrylic resin, polyurethane resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, phenolic resin, melamine resin, polycarbonate resin, polyacetal resin, polyphenylene ether resin, polyphenylene sulfide resin, polysulfone resin, styrene-acrylonitrile copolymer (AS resin), styrene-(meth)acrylic acid copolymer, styrene-methyl methacrylate copolymer, acrylonitrile-butadiene-styrene copolymer (ABS resin), methyl methacrylate-butadiene-styrene copolymer (MBS resin), etc.

Other resins that may be used include biomass-derived polylactic acid (PLA), polybutyl succinate (PBS), polybutyl succinate adipate (PBSA), and polyhydroxyalkanoic acid (PHA, e.g., polyhydroxybutyric acid (PHB)). These biomass-derived resins are particularly preferred from the perspective of utilizing biomass resources.

The content of other resins in the resin composition is preferably 45% by mass or less, more preferably 30% by mass or less, of the total amount of crystalline cellulose resin and other resins, and it is particularly preferable that none are contained.

(Additive (A))
The additive (A) is a compound that satisfies the above formula (1) in relation to the crystalline cellulose resin contained in the resin composition. Specifically, the additive (A) is a compound that can adjust the melting point T2 [°C] of a mixture (hereinafter also referred to as mixture (X)) obtained by mixing the crystalline cellulose resin and the additive (A) in a mass ratio of 9:1 to 0.93 times or less the melting point T1 [°C] of the crystalline cellulose resin alone.

Equation (1) is expressed as T2≦T1×0.93. Rearranging this gives T2/T1≦0.93. Hereinafter, the value (T2/T1) obtained by dividing the melting point T2 of the mixture (S) by the melting point T1 of the crystalline cellulose resin alone is referred to as the melting point depression degree of additive (A) relative to the crystalline cellulose resin. The melting point depression degree of additive (A) relative to the crystalline cellulose resin is preferably 0.91 or less, and more preferably 0.89 or less. Although this depends on the composition of the resin composition, the lower the melting point depression degree of additive (A) relative to the crystalline cellulose resin, the more excellent the hot-melt moldability of the resulting resin composition.

The difference between the melting point T1 of the crystalline cellulose resin alone and the melting point T2 of the mixture (S) is preferably 25° C. or more. That is, it is preferable that the following formula (4) is satisfied.
Formula (4) T1-T2≧25 [℃]
In formula (4), T1-T2 refers to the melting point difference between the crystalline cellulose resin and the mixture (S). The melting point difference between the crystalline cellulose resin and the mixture (S) is more preferably 30°C or more. Although it depends on the composition of the resin composition, the greater the melting point difference between the crystalline cellulose resin and the mixture (S) of the additive (A), the more excellent the hot melt moldability of the resin composition obtained.

The additive (A) preferably satisfies the following (i), (ii) or (iii) in the following formula (2):
(i) Vu/V1<1.0 and χ<3
(ii) 1.0≦Vu/V1<1.5 and χ<6
(iii) 1.5≦Vu/V1 and χ<8
Formula (2) 1/Tm-1/Tm ⁰ = (R/△Hu)×(Vu/V1)×(ν ₁ −χν ₁ ² )

In formula (2), the symbols have the following meanings.
Tm: melting point (absolute temperature [K]) of a mixture obtained by adding 10 parts by mass of the additive to 90 parts by mass of the crystalline cellulose resin
Tm ⁰ : Melting point of the crystalline cellulose resin alone (absolute temperature [K])
R: gas constant ΔHu: heat of fusion per mole of the repeating unit forming the crystalline cellulose resin [J/mol]
V1: molar volume of the additive; Vu: molar volume of the repeating unit forming the crystalline cellulose resin; ν ₁ : volume fraction of the additive in a mixture in which 10 parts by mass of the additive are added to 90 parts by mass of the crystalline cellulose resin; χ: parameter indicating the interaction between the crystalline cellulose resin and the additive.

Tm [K] and Tm ⁰ [K] in formula (2) are the absolute temperatures of T2 [°C] and T1 [°C] in formula (1), respectively. Tm [K] and Tm ⁰ [K] can be determined by conversion from T2 [°C] and T1 [°C] measured using a DSC device as described above. In this specification, although units may not be added to these symbols, the units of Tm and Tm ⁰ are [K], and the units of T2 and T1 are [°C].

R is the gas constant, and 8.31 [J/K mol] was used. ΔHu is the heat of fusion [J/mol] per mole of repeating units forming the crystalline cellulose resin, and was measured using a DSC device. That is, the heat of fusion per mole of crystalline cellulose resin (J/mol) determined from the area of the endothermic peak upon melting of the crystalline cellulose resin alone measured using a DSC device, divided by the number of units constituting the crystalline cellulose resin, was used as ΔHu. V1, Vu, and _v1 can each be calculated from literature values, etc.

The values other than χ in formula (2) are determined as described above and inserted into formula (2) to determine χ. χ is a parameter that indicates the interaction between the crystalline cellulose resin and additive (A). As explained above, in embodiments of the resin composition of the present invention, the smaller the value, the better. Specifically, χ is preferably less than 8, more preferably 3 or less, and even more preferably 0 or less.

Note that χ can be adjusted appropriately depending on the value of Vu/V1 in equation (2), dividing into cases (i), (ii), and (iii).

When Vu/V1 is less than 1.0, it is preferable that χ is less than 3 due to condition (i). Furthermore, when Vu/V1 is 1.0 or greater but less than 1.5, it is preferable that χ is less than 6 due to condition (ii). When Vu/V1 is 1.5 or greater, it is preferable that χ is less than 8 due to condition (iii).

In equation (2), when the left-hand side of the formula is the same, the larger Vu/V1 is, the larger χ tends to be. The left-hand side of equation (2) becomes larger the smaller the degree of melting point depression, in relation to equation (1). When additive (A) is used, the left-hand side of equation (2) can be increased, and the value of χ can be reduced even if Vu/V1 is relatively large.

The structure of additive (A) is not limited as long as it is a compound that satisfies formula (1). However, common structures of additive (A) that can satisfy formula (1) include structures having multiple amino groups, hydroxy groups, or carboxy groups within the molecule, and structures having nitrogen-containing heterocycles. These structures include ammonium groups in which amino groups are quaternized, onium groups, ester groups in which multiple amino groups, hydroxy groups, or carboxy groups are condensed within the molecule, amide groups, acid anhydrides, imide groups, etc. It is also preferable that additive (A) have an aromatic ring within the molecule.

Preferred examples of additive (A) include amino alcohols having a structure represented by the following general formula RAa or RAb, and nitrogen-containing aromatic heterocyclic five-membered ring compounds having a structure represented by the following general formula RB. Hereinafter, compounds having a structure represented by general formula RAa may be abbreviated as "compound RAa." Compounds having structures represented by other general formulas may also be abbreviated in the same manner. Compound RAa and compound RAb will be collectively referred to as "compound RA."

In the formula, R ¹ and R ² each independently represent a divalent linking group. R ³ each independently represent a hydrogen atom or a substituent. R ⁴ represents a hydrogen atom, a substituted or unsubstituted alkyl group, or an aryl group. X ⁻ represents an organic or inorganic monovalent anion.

In the formula, A represents a nitrogen-containing aromatic heterocyclic 5-membered ring. ^R5 is an atom or group bonded to a ring-constituting atom of A and represents a hydrogen atom or a substituent. n represents the total number of atoms or groups bonded to the ring-constituting atoms of A. When n is 2 or more, multiple ^R5s may be the same or different, or may be bonded to each other to form an aromatic ring structure. ^R5 bonded to the heteroatom may have an onium salt structure, in which case the counter anion is an organic or inorganic anion.

Compounds that are not included in Compound RA or Compound RB but have a structure that is preferred as the additive (A) above are referred to as "Compound RC." Compound RC includes compounds that have a structure containing multiple amino groups, hydroxy groups, and carboxy groups in the molecule, but do not have the structure of Compound RA or Compound RB. Specific examples of Compound RC include Compounds R-1 to R-11, whose structures are represented by R-1 to R-11 below, respectively.

Additive (A) may be used alone or in combination with two or more types. When two or more types are used in combination, the mixture of the two or more types satisfies formula (1). Of these, compound RA and compound RB are preferred as additive (A). Compound RA and compound RB are described in more detail below.

<Compound RA>
Of the compounds RA, the compound RAa is a primary, secondary or tertiary amino alcohol, and the compound RAb is a quaternary amino alcohol.

In general formula RAa and general formula RAb, R ¹ and R ² each independently represent a divalent linking group. Specific examples of ^{R 1} and R ² each independently include a substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms, which may have a nitrogen atom between carbon atoms, and which is linear or branched and may have a cyclic structure. Examples of the substituent in the divalent hydrocarbon group include a hydroxy group and an amino group, with a hydroxy group being preferred.

^R1 and ^R2 each have a branched chain, and the branched chains may be bonded to each other to form a nitrogen atom-containing heterocycle having 4 to 7 members. In this case, the heterocycle is preferably a 5-membered ring.

Examples of R ¹ and R ² include -C _n H _2n - (n is an integer of 1 to 10, and preferably 2 or 3; _{C n} H _2n may be branched), -C _m H _2m -N(-C _s H _2s -OH)-C _t H _2t - (m, s, and t are each independently an integer of 1 to 10, and preferably m is 2 or 3; s and t are preferably 1 to 3; C _m H _2m , C _s H _2s , and C _t H _2t may be branched), and the like.

In general formulae RAa and RAb, ^R3 represents a hydrogen atom or a substituent. When R3 is a substituent, examples of ^R3 include a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, which may be linear or branched and have a cyclic structure. Examples of ^R3 include an aryl group having 4 to 10 carbon atoms, a heteroaromatic ring group, or an alkyl group having 1 to 10 carbon atoms, which may have a substituent. Examples of the substituent on the aryl group, heteroaromatic ring group, or alkyl group include a halogen atom such as F, Cl, or Br, a hydroxy group, an aryl group bonded via an amide bond, an ester bond, or an ether bond, an aralkyl group, an alkyl group, an alkenyl group, or an alkynyl group. Examples of the aryl group include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group.

In general formula RAb, ^R4 represents a hydrogen atom, a substituted or unsubstituted alkyl group, or an aryl group. Specific examples of ^R4 can be the same as those of ^R3 . ^X- represents an organic or inorganic monovalent anion. Examples of the monovalent anion include halogen ions such as ^F- , ^Cl- , and ^{Br- ,} and organic anions such as _{CH3COO- and} ^CF3COO- .

Specific examples of compound RAa include compounds RAa-1 to RAa-9, whose structures are represented below in RAa-1 to RAa-9, respectively. Specific examples of compound RAb include compounds RAb-10 to RAb-11, whose structures are represented below in RAb-10 to RAb-11, respectively.

<Compound RB>
Compound RB is a nitrogen-containing aromatic heterocyclic five-membered compound having a structure represented by the general formula RB. In the formula, A represents a nitrogen-containing aromatic heterocyclic five-membered ring. Ring A can have 1 to 3 nitrogen atoms, preferably 1 or 2. Ring A may have another heteroatom other than the nitrogen atom. Examples of the other heteroatom include an oxygen atom and a sulfur atom.

Examples of ring A include a pyrrole ring, imidazole ring, pyrazole ring, triazole ring, thiazole ring, oxazole ring, oxadiazole ring, thiadiazole ring, dioxazole ring, dithiazole ring, and tetrazole ring.

^R5 is an atom or group bonded to a ring-constituting atom of A and represents a hydrogen atom or a substituent. n represents the total number of atoms or groups bonded to the ring-constituting atoms of A. When n is 2 or more, multiple ^R5s may be the same or different, and may be bonded to each other to form an aromatic ring structure.

When ^R5 is a substituent, for example, it can be a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, which can be linear or branched and optionally have a cyclic structure. Examples of ^R5 include an aryl group having 4 to 10 carbon atoms, a heteroaromatic ring group, or an alkyl group having 1 to 10 carbon atoms, which can have a substituent. Examples of the substituent on the aryl group, heteroaromatic ring group, or alkyl group can include a halogen atom such as F, Cl, or Br, an aryl group bonded via an amide bond, an ester bond, or an ether bond, an aralkyl group, an alkyl group, an alkenyl group, or an alkynyl group, etc. Examples of the aryl group can include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, etc.

When multiple ^R5s are bonded to each other to form an aromatic ring structure, it is preferable that two adjacent ^R5s are bonded to each other. The aromatic ring formed in this manner is referred to as ring B. Ring B preferably has 5 to 7 members and may have 1 to 3 heteroatoms. The heteroatoms in ring B may be in positions shared with ring A, or may be in positions that are not shared. The heteroatoms in ring B are preferably selected from a nitrogen atom, an oxygen atom, and a sulfur atom.

Ring B may have a substituent, and examples of the substituent include halogen atoms such as F, Cl, and Br, as well as aryl, aralkyl, alkyl, alkenyl, or alkynyl groups bonded via an amide bond, ester bond, or ether bond, as described above.

^R5 bonded to the heteroatom may have an onium salt structure, in which case the counter anion is an organic or inorganic anion. When the heteroatom is a nitrogen atom, the counter anion is a monovalent anion. Examples of monovalent anions include halogen ions such as F ^- , Cl ^- , and Br ^{- ,} and organic anions such as CH ₃ COO ^- and CF ₃ COO ^- .

Specific examples of compound RB include compounds RB-1 to RB-9, whose structures are represented below as RB-1 to RB-9, respectively.

Additive (A) is selected appropriately depending on the type of crystalline cellulose resin, within the range satisfying formula (1), preferably within the range satisfying formula (4), or within the range satisfying conditions (i), (ii), or (iii).

A preferred combination of the crystalline cellulose resin and additive (A) in the resin composition of the present invention is, for example, a combination in which the crystalline cellulose resin is a crystalline cellulose ester resin having an acetyl substitution degree of 2.7 or more, and the additive (A) is Compounds R-1 to R-11, RA, or RB. In this combination, the additive (A) is preferably Compound RA or RB, and more preferably Compound RAa-1, RAa-9 , RB-3, or RB-6.

The resin composition of the present invention containing additive (A) is a resin composition for hot melt molding, and is used by heating the resin composition to near its melting temperature during molding. Therefore, it is preferable that additive (A) has properties that prevent substantial evaporation or sublimation when heated during molding. Specifically, the boiling point of additive (A) is preferably 200°C or higher, and more preferably 230°C or higher.

The content of additive (A) in the resin composition of the present invention is preferably 5 to 30 parts by mass, and more preferably 10 to 25 parts by mass, per 100 parts by mass of the total amount of crystalline cellulose resin and additive (A). By keeping the content of additive (A) within the above range, the hot melt moldability of the resin composition is improved, and the good physical properties of the cellulose resin can be fully maintained in the resulting hot melt molded product.

(Other additives)
The resin composition of the present invention may contain, as necessary, additives other than the additive (A) as additives to the resin, within the range that does not impair the effects of the present invention.

Other additives include plasticizers, heat stabilizers, antioxidants, release agents, UV absorbers, dyes and pigments, flame retardants, antistatic agents, anti-fogging agents, lubricants/anti-blocking agents, flow improvers, dispersants, deodorizers, and antibacterial agents.

Known plasticizers can be used as long as they do not impair the effects of the present invention. Specific examples of plasticizers include polyester compounds, polyhydric alcohol ester compounds, polycarboxylic acid ester compounds (including phthalate ester compounds), glycolate compounds, and ester compounds (including fatty acid ester compounds and phosphate ester compounds). These may be used alone or in combination of two or more types.

The diol constituting the polyester compound is an aromatic diol, an aliphatic diol, or an alicyclic diol, preferably an aliphatic diol, and more preferably a diol having 1 to 4 carbon atoms. The diol may be one type or a mixture of two or more types.

In particular, the polyester compound preferably contains repeating units obtained by reacting at least a dicarboxylic acid containing an aromatic dicarboxylic acid with a diol having 1 to 4 carbon atoms, and more preferably contains repeating units obtained by reacting a dicarboxylic acid containing an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid with a diol having 1 to 4 carbon atoms.

Both ends of the polyester compound molecule may or may not be sealed, but from the standpoint of reducing the moisture permeability of the hot-melt molded product, it is preferable that they are sealed.

The polyester compound is preferably a compound having a structure represented by the following general formula (I) or (II), where n is an integer of 1 or greater.

General formula (I)
B-(G-A) _n -G-B
General formula (II)
C-(A-G) _n -A-C
In general formulas (I) and (II), A represents a divalent group derived from an alkylene dicarboxylic acid having 3 to 20 carbon atoms (preferably 4 to 12), a divalent group derived from an alkenylene dicarboxylic acid having 4 to 20 carbon atoms (preferably 4 to 12), or a divalent group derived from an aryl dicarboxylic acid having 8 to 20 carbon atoms (preferably 8 to 12).

Examples of the divalent group for A derived from an alkylene dicarboxylic acid having 3 to 20 carbon atoms include divalent groups derived from 1,2-ethanedicarboxylic acid (succinic acid), 1,3-propanedicarboxylic acid (glutaric acid), 1,4-butanedicarboxylic acid (adipic acid), 1,5-pentanedicarboxylic acid (pimelic acid), 1,8-octanedicarboxylic acid (sebacic acid), etc. Examples of the divalent group for A derived from an alkenylene dicarboxylic acid having 4 to 20 carbon atoms include divalent groups derived from maleic acid, fumaric acid, etc. Examples of the divalent group for A derived from an aryl dicarboxylic acid having 8 to 20 carbon atoms include divalent groups derived from benzene dicarboxylic acids such as 1,2-benzenedicarboxylic acid (phthalic acid), 1,3-benzenedicarboxylic acid, and 1,4-benzenedicarboxylic acid, and naphthalene dicarboxylic acids such as 1,5-naphthalene dicarboxylic acid.

A may be a single type or a combination of two or more types. Among these, a combination of an alkylene dicarboxylic acid having 4 to 12 carbon atoms and an aryl dicarboxylic acid having 8 to 12 carbon atoms is preferred.

G in general formulas (I) and (II) represents a divalent group derived from an alkylene glycol having 2 to 20 carbon atoms (preferably 2 to 12), a divalent group derived from an aryl glycol having 6 to 20 carbon atoms (preferably 6 to 12), or a divalent group derived from an oxyalkylene glycol having 4 to 20 carbon atoms (preferably 4 to 12).

Examples of divalent groups derived from alkylene glycols having 2 to 20 carbon atoms in G include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), and 2,2-diethyl-1,3-propanediol. divalent groups derived from 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylol pentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylol heptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-octadecanediol, etc.

Examples of divalent groups in G derived from aryl glycols having 6 to 20 carbon atoms include divalent groups derived from 1,2-dihydroxybenzene (catechol), 1,3-dihydroxybenzene (resorcinol), 1,4-dihydroxybenzene (hydroquinone), etc. Examples of divalent groups in G derived from oxyalkylene glycols having 4 to 20 carbon atoms include divalent groups derived from diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, etc.

G may be one type or a combination of two or more types. Among these, it is preferable that G is an alkylene glycol having 2 to 12 carbon atoms.

B in general formula (I) is a monovalent group derived from an aromatic ring-containing monocarboxylic acid or an aliphatic monocarboxylic acid.

In the monovalent group derived from an aromatic ring-containing monocarboxylic acid, the aromatic ring-containing monocarboxylic acid is a carboxylic acid that contains an aromatic ring within the molecule, and includes not only those in which the aromatic ring is directly bonded to the carboxy group, but also those in which the aromatic ring is bonded to the carboxy group via an alkylene group or the like. Examples of monovalent groups derived from an aromatic ring-containing monocarboxylic acid include monovalent groups derived from benzoic acid, para-tert-butylbenzoic acid, orthotoluic acid, meta-toluic acid, para-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal-propylbenzoic acid, aminobenzoic acid, acetoxybenzoic acid, phenylacetic acid, 3-phenylpropionic acid, etc.

Examples of monovalent groups derived from aliphatic monocarboxylic acids include monovalent groups derived from acetic acid, propionic acid, butanoic acid, caprylic acid, caproic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid, etc. Of these, monovalent groups derived from alkyl monocarboxylic acids in which the alkyl portion has 1 to 3 carbon atoms are preferred, with an acetyl group (a monovalent group derived from acetic acid) being more preferred.

C in general formula (II) is a monovalent group derived from an aromatic ring-containing monoalcohol or an aliphatic monoalcohol.

Aromatic ring-containing monoalcohols are alcohols that contain an aromatic ring within the molecule, and include not only those in which the aromatic ring is directly bonded to an OH group, but also those in which the aromatic ring is bonded to an OH group via an alkylene group or the like. Examples of monovalent groups derived from aromatic ring-containing monoalcohols include monovalent groups derived from benzyl alcohol, 3-phenylpropanol, etc.

Examples of monovalent groups derived from aliphatic monoalcohols include monovalent groups derived from methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, isopentanol, hexanol, isohexanol, cyclohexyl alcohol, octanol, isooctanol, 2-ethylhexyl alcohol, nonyl alcohol, isononyl alcohol, tert-nonyl alcohol, decanol, dodecanol, dodecahexanol, dodecaoctanol, allyl alcohol, oleyl alcohol, etc. Among these, monovalent groups derived from alcohols having 1 to 3 carbon atoms, such as methanol, ethanol, propanol, and isopropanol, are preferred.

The weight-average molecular weight of the polyester compound is preferably in the range of 500 to 3,000, and more preferably in the range of 600 to 2,000. If the weight-average molecular weight is within the above range, the polyester compound is more likely to meet the bleed-out resistance requirements of the hot-melt molded article of the present invention. The weight-average molecular weight can be measured by gel permeation chromatography (GPC) as described above.

The polyhydric alcohol ester compound is an ester compound (alcohol ester) of a dihydric or higher aliphatic polyhydric alcohol with a monocarboxylic acid, and is preferably a di- to 20-hydric aliphatic polyhydric alcohol ester. The polyhydric alcohol ester compound preferably has an aromatic ring or a cycloalkyl ring in the molecule.

Preferred examples of aliphatic polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, trimethylolpropane, pentaerythritol, trimethylolethane, xylitol, etc. Of these, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, xylitol, etc. are preferred.

The monocarboxylic acid is not particularly limited and may be an aliphatic monocarboxylic acid, an alicyclic monocarboxylic acid, or an aromatic monocarboxylic acid. To increase the moisture permeability and reduce volatility of the hot-melt molded product, an alicyclic monocarboxylic acid or an aromatic monocarboxylic acid is preferred. The monocarboxylic acid may be a single type or a mixture of two or more types. Furthermore, all of the OH groups contained in the aliphatic polyhydric alcohol may be esterified, or some may remain as OH groups.

The aliphatic monocarboxylic acid is preferably a fatty acid having a straight or branched chain and 1 to 32 carbon atoms. The number of carbon atoms in the aliphatic monocarboxylic acid is more preferably 1 to 20, and even more preferably 1 to 10. Examples of aliphatic monocarboxylic acids include saturated fatty acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethylhexanoic acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, heptacosanoic acid, montanic acid, melissic acid, and lacteric acid; and unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid. Among these, acetic acid or a mixture of acetic acid and other monocarboxylic acids is preferred in order to enhance compatibility with cellulose acetate.

Examples of alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, etc.

Examples of aromatic monocarboxylic acids include benzoic acid; benzoic acid with one to three alkyl or alkoxy groups (e.g., methoxy or ethoxy groups) introduced into the benzene ring (e.g., toluic acid); and aromatic monocarboxylic acids with two or more benzene rings (e.g., biphenylcarboxylic acid, naphthalenecarboxylic acid, tetralincarboxylic acid), with benzoic acid being preferred.

Specific examples of polyhydric alcohol ester compounds include the compounds described in paragraphs [0058] to [0061] of JP-A No. 2006-113239.

The polycarboxylic acid ester compound is an ester compound of a divalent or higher polycarboxylic acid, preferably a divalent to 20-valent polycarboxylic acid, and an alcohol compound. The polycarboxylic acid is preferably a divalent to 20-valent aliphatic polycarboxylic acid, a trivalent to 20-valent aromatic polycarboxylic acid, or a trivalent to 20-valent alicyclic polycarboxylic acid.

Examples of polycarboxylic acids include aromatic polycarboxylic acids with a valence of three or more, such as trimellitic acid, trimesic acid, and pyromellitic acid, or derivatives thereof; aliphatic polycarboxylic acids, such as succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid, maleic acid, and tetrahydrophthalic acid; and oxypolycarboxylic acids, such as tartaric acid, tartronic acid, malic acid, and citric acid. Oxypolycarboxylic acids are preferred in order to suppress volatilization from hot-melt molded articles.

Examples of alcohol compounds include linear or branched aliphatic saturated alcohol compounds, linear or branched aliphatic unsaturated alcohol compounds, alicyclic alcohol compounds, and aromatic alcohol compounds. The number of carbon atoms in the aliphatic saturated alcohol compounds or aliphatic unsaturated alcohol compounds is preferably 1 to 32, more preferably 1 to 20, and even more preferably 1 to 10. Examples of alicyclic alcohol compounds include cyclopentanol and cyclohexanol. Examples of aromatic alcohol compounds include benzyl alcohol and cinnamyl alcohol.

There are no particular restrictions on the molecular weight of the polycarboxylic acid ester compound, but it is preferably in the range of 300 to 1,000, and more preferably in the range of 350 to 750. From the perspective of suppressing bleed-out, a larger molecular weight of the polycarboxylic acid ester plasticizer is preferable; from the perspective of moisture permeability and compatibility with cellulose acetate, a smaller molecular weight is preferable.

Examples of polycarboxylic acid ester compounds include triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl tribenzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, tributyl trimellitate, tetrabutyl pyromellitate, etc.

The polycarboxylic acid ester compound may be a phthalate ester compound. Examples of phthalate ester compounds include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, and dicyclohexyl terephthalate.

Examples of glycolate compounds include alkylphthalyl alkyl glycolates. Examples of alkylphthalyl alkyl glycolates include methylphthalyl methyl glycolate, ethylphthalyl ethyl glycolate, propylphthalyl propyl glycolate, butylphthalyl butyl glycolate, octylphthalyl octyl glycolate, methylphthalyl ethyl glycolate, ethylphthalyl methyl glycolate, ethylphthalyl propyl glycolate, methylphthalyl butyl glycolate, ethylphthalyl butyl glycolate, butylphthalyl methyl glycolate, butylphthalyl ethyl glycolate, propylphthalyl butyl glycolate, butylphthalyl propyl glycolate, methylphthalyl octyl glycolate, ethylphthalyl octyl glycolate, octylphthalyl methyl glycolate, and octylphthalyl ethyl glycolate, with ethylphthalyl ethyl glycolate being preferred.

Ester compounds include fatty acid ester compounds, citrate ester compounds, phosphate ester compounds, etc.

Examples of fatty acid ester compounds include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate. Examples of citrate ester compounds include acetyltrimethyl citrate, acetyltriethyl citrate, and acetyltributyl citrate. Examples of phosphate ester compounds include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, biphenyl diphenyl phosphate, trioctyl phosphate, and tributyl phosphate, with triphenyl phosphate being preferred.

Of these, polyester compounds, polyhydric alcohol ester compounds, and glycolate compounds are preferred, with polyester compounds and polyhydric alcohol ester compounds being particularly preferred.

The content of the plasticizer is preferably in the range of 1 to 30 parts by mass, and more preferably in the range of 1.5 to 15 parts by mass, per 100 parts by mass of the total of the resin and additive (A) in the resin composition of the present invention. When the content of the plasticizer is within the above range, the effect of imparting plasticity can be exerted, and the resistance to exudation of the plasticizer from the hot-melt molded product is also excellent.

Examples of heat stabilizers include phosphorus-based compounds. Any conventionally known phosphorus-based compound can be used. Specific examples include phosphorus oxoacids such as phosphoric acid, phosphonic acid, phosphorous acid, phosphinic acid, and polyphosphoric acid; metal acid pyrophosphates such as sodium acid pyrophosphate, potassium acid pyrophosphate, and calcium acid pyrophosphate; phosphates of Group 1 or Group 2 metals such as potassium phosphate, sodium phosphate, cesium phosphate, and zinc phosphate; organic phosphate compounds, organic phosphite compounds, and organic phosphonite compounds.

The content of the above phosphorus-based compound is typically 0.001 to 1 part by mass, preferably 0.01 to 0.7 parts by mass, and more preferably 0.03 to 0.5 parts by mass per 100 parts by mass of the resin and additive (A) in the resin composition of the present invention.

Antioxidants are also called anti-degradants. Hindered phenol compounds are preferably used as antioxidants, such as 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butyla N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tris-(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, and the like.

2,6-di-t-butyl-p-cresol, pentaerythrityl tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], and triethylene glycol bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate] are particularly preferred. Hydrazine-based metal deactivators such as N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine and phosphorus-based processing stabilizers such as tris(2,4-di-t-butylphenyl)phosphite may also be used in combination.

The release agent may be at least one compound selected from the group consisting of aliphatic carboxylic acids, esters of aliphatic carboxylic acids and alcohols, aliphatic hydrocarbon compounds with a number-average molecular weight of 200 to 15,000, and polysiloxane-based silicone oils. The content of the release agent is typically 0.001 to 2 parts by mass, and preferably 0.01 to 1 part by mass, per 100 parts by mass of the resin and additive (A) in the resin composition of the present invention combined.

Examples of UV absorbers include inorganic UV absorbers such as cerium oxide and zinc oxide, as well as organic UV absorbers such as benzotriazole compounds, benzophenone compounds, and triazine compounds. Among these, organic UV absorbers are preferred. In particular, at least one selected from the group consisting of benzotriazole compounds, 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]phenol, 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)phenol, 2,2'-(1,4-phenylene)bis[4H-3,1-benzoxazin-4-one], and [(4-methoxyphenyl)-methylene]-propanediic acid dimethyl ester is preferred. The content of the ultraviolet absorber is usually 0.01 to 3 parts by mass, preferably 0.1 to 1 part by mass, per 100 parts by mass of the total of the resin and additive (A) in the resin composition of the present invention.

Dyes and pigments include inorganic pigments, organic pigments, and organic dyes. Examples of inorganic pigments include sulfide-based pigments such as carbon black, cadmium red, and cadmium yellow; silicate-based pigments such as ultramarine; oxide-based pigments such as titanium oxide, zinc white, red iron oxide, chromium oxide, iron black, titanium yellow, zinc-iron brown, titanium-cobalt green, cobalt green, cobalt blue, copper-chromium black, and copper-iron black; chromate-based pigments such as yellow lead and molybdate orange; and ferrocyanide-based pigments such as iron blue. The content of the dye or pigment is typically 5 parts by mass or less, preferably 3 parts by mass or less, and more preferably 2 parts by mass or less, per 100 parts by mass of the combined total of the resin and additive (A) in the resin composition of the present invention.

Examples of flame retardants include halogenated flame retardants such as halogenated bisphenol A polycarbonate, brominated bisphenol epoxy resin, brominated bisphenol phenoxy resin, and brominated polystyrene; phosphate ester flame retardants; organometallic salt flame retardants such as dipotassium diphenylsulfone-3,3'-disulfonate, potassium diphenylsulfone-3-sulfonate, and potassium perfluorobutanesulfonate; and polyorganosiloxane flame retardants, with phosphate ester flame retardants being preferred. The content of the flame retardant is typically 1 to 30 parts by mass, preferably 3 to 25 parts by mass, and more preferably 5 to 20 parts by mass per 100 parts by mass of the combined total of the resin and additive (A) in the resin composition of the present invention.

In addition, commercially available products such as Adeka Cizer O-130P (manufactured by ADEKA Corporation, epoxy-based plasticizer) and Irgaphos 168 (manufactured by BASF Japan; tris(2,4-di-t-butylphenyl)phosphite) may also be used as the various additives mentioned above.

Various fillers can also be added. There are no particular restrictions on the fillers used, as long as they are commonly used in resin compositions for hot melt molding. Powdered, fibrous, granular, and plate-like inorganic fillers are preferred, as are resin-based fillers and natural fillers. Inorganic or organic fine particles are preferably used as fillers.

Examples of inorganic fine particles include fine particles of silicon dioxide (silica), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate. Of these, silicon dioxide fine particles and zirconium oxide fine particles are preferred, and silicon dioxide fine particles are more preferred.

Examples of silicon dioxide microparticles include Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600, and NAX50 (all manufactured by Nippon Aerosil Co., Ltd.), and Seahoster KE-P10, KE-P30, KE-P50, and KE-P100 (all manufactured by Nippon Shokubai Co., Ltd.). Of these, Aerosil R972V, NAX50, and Seahoster KE-P30 are particularly preferred as they reduce the coefficient of friction.

The primary particle diameter of the microparticles is preferably in the range of 5 to 50 nm, and more preferably in the range of 7 to 20 nm. A larger primary particle diameter is more effective in increasing the slipperiness of the resulting molded product, but is more likely to reduce transparency. Therefore, the microparticles may be contained as secondary aggregates with particle diameters in the range of 0.05 to 0.3 μm. The size of the primary particles or secondary aggregates of the microparticles can be determined by observing the primary particles or secondary aggregates with a transmission electron microscope at a magnification of 500,000 to 2,000,000 times, and calculating the average particle diameter of 100 primary particles or secondary aggregates.

The content of the microparticles is preferably in the range of 0.05 to 1.0 parts by mass, and more preferably in the range of 0.1 to 0.8 parts by mass, per 100 parts by mass of the total of the resin and additive (A) in the resin composition of the present invention.

(Production of resin composition)
The resin composition of the present invention is obtained by appropriately mixing the essential components, crystalline cellulose resin and additive (A), and the above-mentioned optional components. In order to fully exhibit the effects of the present invention when used in hot melt molding, it is preferable that the components are sufficiently mixed at the molecular level.

Specific examples of methods for producing a resin composition include dissolving the crystalline cellulose resin, additive (A), and optional components in a solvent capable of dissolving at least the crystalline cellulose resin and additive (A) (dispersing any optional components that are not soluble), thoroughly mixing the components, and then removing the solvent to obtain a mixture (resin composition).

Alternatively, a solution of additive (A) and other optional additives dissolved or dispersed in a solvent, or additive (A) and other optional additives, when used with crystalline cellulose resin or optionally other resins, may be added to the crystalline cellulose resin and other resins (hereinafter simply referred to as "resin components") and mixed in a mixer. Examples of mixers that can be used include a Banbury mixer, a roll mixer, and a Brabender mixer.

In the above method, additive (A) and other additives may be added to the resin components in several batches to prevent localized high concentrations of additive (A) and other additives. Furthermore, mixing at a temperature of 50°C to 200°C is preferred, using a mixer that is kept warm or that utilizes kinetic energy during mixing.

In order to prevent decomposition of the crystalline cellulose resin, it is preferable that the temperature during mixing be no more than T1 x 0.75 + 20°C, as in the case of hot melt molding, which will be described later. If the mixing temperature rises due to the kinetic energy of mixing, it is preferable to prevent the temperature of the mixture from exceeding T1 x 0.75 + 20°C by cooling with cooling water, air cooling, or by stopping the mixing operation and allowing it to cool naturally.

Furthermore, during the above mixing, additive (A) and other additives may be thoroughly mixed together and added to the resin component as an additive mixture. It is also preferable to add additive (A) to crystalline cellulose resin to form a composition with a lowered melting point (hot melt processing temperature) and mix it.

The resin composition of the present invention may be obtained, for example, by mixing the above-mentioned components using a mixer according to the above-mentioned method, followed by further melt-kneading. The mixer may be the same as the mixer described above, and melt-kneading may be performed using a single-screw kneading extruder, twin-screw kneading extruder, kneader, or the like. It is also possible to melt-knead the components without pre-mixing them, or by pre-mixing only some of the components and feeding them into an extruder using a feeder.

The temperature during melt-kneading (melt-kneading temperature) is set appropriately depending on the type and composition of the crystalline cellulose resin and additive (A). The melt-kneading temperature does not need to be equal to or higher than the melting temperature of the resin composition; for example, from the perspective of suppressing decomposition of the crystalline cellulose resin, it is preferable to carry out the melt-kneading at a temperature equal to or lower than T1 x 0.75 + 20°C, as described above.

In melt kneading, the kneaded material is extruded into strands, and the strand-shaped kneaded material can then be processed into pellets, flakes, or other shapes.

The resin composition of the present invention can take various forms, such as powder, granules, tablets, pellets, flakes, fibers (filaments), and liquid.

[Hot melt molded products]
The hot melt molded article of the present invention can be obtained by hot melt molding the resin composition of the present invention. As the hot melt molding method, any known hot melt molding method using a general thermoplastic resin composition can be applied without any particular limitation. As a preferred molding method, the molding method of the present invention described below can be mentioned.

When producing hot melt molded products, for example, the resin composition can be hot melted in various molding machines and molded into the desired shape. Molding methods commonly used for thermoplastic resins can be used. Examples include general injection molding, ultra-high speed injection molding, injection compression molding, two-color molding, gas-assisted and other hollow molding methods, molding using insulated molds, molding using rapidly heated molds, foam molding (including supercritical fluids), insert molding, IMC (in-mold coating) molding, extrusion molding, compression molding, blow molding, calendar molding, inflation molding, sheet molding, thermoforming, rotational molding, laminate molding, press molding, and fused deposition modeling.

Moulding methods using the hot runner system can also be used. Sheet or film-shaped products obtained by extrusion moulding and calendar moulding can also be subjected to secondary moulding such as vacuum moulding and pressure moulding.

Suitable molding methods for the resin composition of the present invention include injection molding, extrusion molding, and fused deposition modeling. Extrusion molding includes melt spinning, in which a molten resin composition is extruded into fibers using a melt extrusion spinning machine. Fused deposition modeling, also known as FDM (Fused Deposition Modeling), is a molding method based on three-dimensional printing (also known as "3D printing") technology and performed using a 3D printer.

The hot-melt molded article of the present invention is obtained by hot-melt molding at a temperature significantly lower than the decomposition temperature of the crystalline cellulose resin using the resin composition of the present invention. As a result, in the hot-melt molded article of the present invention, decomposition of the crystalline cellulose resin during hot-melt molding is suppressed, and the properties inherent to the crystalline cellulose resin used as the molding raw material, such as transparency, rigidity, and toughness, are maintained.

The degree of suppression of decomposition of the crystalline cellulose resin during hot melt molding can be evaluated, for example, by the ratio (Mw _after / Mw _before ) of the weight average molecular weight of the crystalline cellulose resin in the hot melt molded product to the weight average molecular weight (Mw _before ) of the crystalline cellulose resin in the resin composition. The weight average molecular weight (Mw _{after )} of the crystalline cellulose resin in the hot melt molded product can be determined by subjecting a sample scraped off in the same manner as above to GPC. According to the hot melt molded product of the present invention, Mw _after / Mw _before is preferably approximately 0.6 or more, more preferably 0.7 or more, and even more preferably 0.8 or more.

The rigidity of the hot-melt molded article of the present invention can be evaluated using the flexural modulus measured in a bending test conducted in accordance with JIS K7171 as an index. The test specimen used in the bending test is a scaled test specimen prepared in accordance with JIS K7139. According to the hot-melt molded article of the present invention, the flexural modulus is preferably 3.0 GPa or more, more preferably 3.5 GPa or more, and even more preferably 4.5 GPa or more.

The toughness of the hot melt molded article of the present invention can be evaluated using the Charpy impact strength measured in a Charpy impact test performed in accordance with JIS K7110 as an index. Test specimens used in the Charpy impact test are strip test specimens prepared in accordance with JIS K7139 and notched using a notching machine (e.g., a Toyo Seiki notching machine). According to the hot melt molded article of the present invention, the Charpy impact strength is preferably 10 kJ/ ^m2 or more, more preferably 12 kJ/ ^m2 or more, and even more preferably 14 kJ/ ^m2 or more.

When the hot-melt molded product of the present invention is a fiber, its physical properties can be evaluated by the strength and elongation at break measured in a tensile test conducted in accordance with JIS L1015. The strength at break of the fiber is preferably 0.5 cN/dtex or more, more preferably 0.9 cN/dtex or more, and even more preferably 1.3 cN/dtex or more. The elongation at break of the fiber is preferably 30% or more, more preferably 40% or more, and even more preferably 45% or more.

The hot melt molded products of the present invention are useful for a variety of applications, including electrical and electronic devices and their parts, office automation equipment, information terminal equipment, machine parts, home appliances, vehicle components, medical equipment, building materials, various containers, leisure goods and miscellaneous items, and lighting equipment, and are particularly expected to be applicable to electrical and electronic devices, vehicle components, and medical equipment.

Examples of housings, covers, keyboards, buttons, and switch components for electrical and electronic devices, office automation equipment, and information terminal devices include display devices such as personal computers, game consoles, and televisions, as well as printers, copiers, scanners, fax machines, electronic organizers and PDAs, electronic desk calculators, electronic dictionaries, cameras, video cameras, mobile phones, recording medium drives and readers, mice, numeric keypads, CD players, MD players, portable radios, and portable audio players.

Vehicle components include headlamps, helmet shields, etc. Interior components include interior door handles, center panels, instrument panels, console boxes, luggage floor boards, and display housings for car navigation systems, etc.

Medical devices include applications in prosthetic limbs and artificial limbs.

[Hot melt molding method]
The molding method of the present invention is a molding method for hot melt molding the resin composition of the present invention, characterized in that the hot melt molding is carried out under conditions that satisfy the following formula (3):
Formula (3) T3≦T1×0.75+20
In formula (3), T3 represents the maximum temperature [°C] of the resin composition during hot melt molding.

The molding method of the present invention can be the same as the molding method for the hot-melt molded product of the present invention described above, and among these, injection molding, extrusion molding, or fused deposition modeling are preferred.

When hot melt molding is performed, it is preferable to do so at a temperature as low as possible below the decomposition temperature of the crystalline cellulose resin. By performing hot melt molding at a temperature equal to or lower than the above T1 x 0.75 + 20°C, decomposition of the crystalline cellulose resin can be sufficiently suppressed. T3 is preferably a temperature equal to or lower than T1 x 0.75 + 10°C.

The resin composition of the present invention has a melting point sufficiently lower than that of the crystalline cellulose resin it contains, allowing it to be hot-melt molded at a low temperature of T1 x 0.75 + 20°C or lower. Furthermore, when hot-melt molding is performed using a molding method that applies strong shear forces, such as injection molding, extrusion molding, or fused deposition modeling, T3 can be further reduced due to the influence of shear forces.

As mentioned above, the maximum temperature when processing the resin composition of the present invention into various forms, such as pellets, can be set to a low temperature of no more than T1 x 0.75 + 20°C. In other words, in the present invention, the crystalline cellulose resin as a resin component can be processed into hot-melt molded products without being exposed to temperatures higher than T1 x 0.75 + 20°C in all steps from the resin composition production stage to hot-melt molding. This suppresses decomposition of the crystalline cellulose resin, allowing for the production of hot-melt molded products with good physical properties.

T3 is the maximum temperature of the resin composition during hot melt molding. While it depends on the hot melt molding method and equipment, in most cases it is the temperature of the resin composition immediately after it emerges from a die or nozzle. For example, in the case of injection molding, T3 is the temperature of the resin composition immediately after it emerges from the die through which the resin composition is injected from the kneader into the mold. In the case of extrusion molding and fused deposition modeling in 3D printing, T3 indicates the temperature of the resin composition immediately after it is extruded from the die or nozzle, respectively.

The molding method of the present invention can be any general melt molding method, with no particular restrictions, as long as the resin composition of the present invention is used and melt molding is performed under conditions that satisfy formula (3). Fused deposition modeling and melt spinning are described below, but the molding method is not limited to these.

(Fused Deposition Modeling)
The fused deposition modeling can be performed using, for example, a 3D printer. In addition to the fused deposition modeling, the 3D printer can also perform fusion molding using an inkjet method, a stereolithography method, a plaster powder lamination method, a laser sintering method (SLS method), etc.

3D printers generally have a chamber that contains a heatable base, an extrusion head mounted in a gantry structure, a heat melter, a resin composition (kneaded material) guide, and a raw material supply section that includes a resin composition cartridge installation section. Some 3D printers have an integrated extrusion head and heat melter.

The extrusion head is mounted on a gantry structure, allowing it to be moved arbitrarily on the X-Y plane of the base. The base is a platform on which the desired three-dimensional object or support material is constructed, and it is preferable that it be designed so that it can be heated and kept warm to ensure adhesion with the laminated material and improve the dimensional stability of the resulting resin object as the desired three-dimensional object. Typically, at least one of the extrusion head and base is movable in the Z-axis direction, which is perpendicular to the X-Y plane.

3D printer molding filament is unwound from the raw material supply section and fed to the extrusion head by a pair of opposing rollers or gears, where it is heated and melted and extruded from the tip nozzle. The temperature of the resin composition immediately after being extruded from the tip nozzle is T3, and is set to a temperature of T1 x 0.75 + 20°C or less, preferably T1 x 0.75 + 10°C or less.

Here, for example, signals sent based on a CAD model cause the extrusion head to move its position while supplying and depositing the resin composition onto the substrate. After this process is complete, the deposited layer is removed from the substrate, and the desired three-dimensional object can be obtained by peeling off support materials and cutting off excess parts as needed.

Examples of means for continuously supplying a resin composition to an extrusion head include a method of feeding the resin composition, a method of feeding powder or liquid from a tank or the like via a metering feeder, and a method of extruding pellets or granules that have been plasticized using an extruder or the like, but from the standpoint of process simplicity and supply stability, a method of feeding the resin composition is most preferred.

(Melt spinning method)
The melt spinning method according to the present invention is a method in which the resin composition of the present invention is heated and melted in a known melt extrusion spinning machine, extruded through a nozzle, spun, and if necessary, drawn and wound up. In this case, the temperature of the resin composition immediately after being extruded through the nozzle is the spinning temperature T3.
The spinning temperature is set to a temperature equal to or lower than T1 x 0.75 + 20°C, preferably 180 to (T1 x 0.75 + 20)°C, and more preferably 190 to (T1 x 0.75 + 20)°C. A spinning temperature of 180°C or higher is preferred because it reduces the melt viscosity and improves melt spinnability. Furthermore, by setting the spinning temperature to T1 x 0.75 + 20°C or lower, thermal decomposition of the crystalline cellulose resin in the resin composition can be suppressed.

To obtain fibers with good mechanical properties, the spinning speed is preferably 300 to 3000 m/min, more preferably 300 to 2500 m/min, and even more preferably 300 to 2000 m/min.

There are no particular restrictions on the cross-sectional shape of the fibers used in the hot melt molded products obtained by the melt spinning method of the present invention, and they may have a circular cross section, or irregular cross sections such as multi-lobal, flat, elliptical, W-shaped, S-shaped, X-shaped, H-shaped, C-shaped, square-shaped, or hollow. They may also be composite fibers such as core-sheath composite, eccentric core-sheath composite, side-by-side composite, or mixed fineness fibers.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these. In the examples, the terms "parts" and "%" are used, but unless otherwise specified, they represent "parts by mass" or "% by mass."

[Crystalline cellulose resin]
As the crystalline cellulose resin, four types of crystalline cellulose ester resins shown in Table I were prepared, each substituted with an Ac group (acetyl group) or with an Ac group and a Pr group (propionyl group). The molecular weight is the weight average molecular weight calculated as a standard polystyrene equivalent, determined by GPC using the method described above. The degrees of Ac group substitution and Pr group substitution were determined using NMR in accordance with ASTM-D817-96, based on the integral ratio of the hydroxy group and each substituent. The degree of acyl group substitution is the sum of the degrees of Ac group substitution and the degree of Pr group substitution.

The melting point T1 [°C] of the crystalline cellulose resin and the heat of fusion per mole of repeating units forming the crystalline cellulose resin △Hu [J/mol] were determined using DSC (DSC7000X (Hitachi High-Tech Science Corporation)).

[Additives]
The additives shown in Table II were prepared. The abbreviations for the additives were the same as those for the compounds. Compounds Cf1, Cf2, and Cf3 are additives outside the scope of the present invention and used for comparison, with the structures shown below. Compounds R-4, RAa-1, RAa- 9, and RB-3 are additives corresponding to Additive (A) having the structure above.

For these additives, T2 was measured as follows using the crystalline cellulose resins shown in Table I to confirm whether they satisfied various conditions such as equation (1).

90 parts of crystalline cellulose resin was dissolved in 1,900 parts of a mixed solvent of methylene chloride and methanol (mixing ratio (mass ratio): methylene chloride:methanol = 9:1), and 10 parts of additive was mixed into the solution. The solvent was then removed using an evaporator, and the solid was then dried at 110°C to obtain a solid. The melting point (T2) of the resulting solid was determined using DSC, and the results shown in Table II were obtained.

Table II shows the melting point depression (T2/T1), melting point difference (T1-T2), Vu/V1, and χ. If the melting point depression (T2/T1) is 0.93 or less, the additive falls within the category of additive (A) of the present invention, which satisfies formula (1). T1-T2 is preferably 25°C or higher. The relationship between Vu/V1 and χ preferably satisfies condition (i), (ii), or (iii).

[Production of injection molded products 1]
The crystalline cellulose resins in Table I and the additives shown in Table II were combined as shown in Table III and injection molded by the following method to produce hot melt molded products 1 to 12. In Table III, the "weight average molecular weight" in the column below the crystalline cellulose resin number indicates the weight average molecular weight of the crystalline cellulose resin x ^103. The same applies to Tables IV to VI.

(1) Preparation of Resin Composition The crystalline cellulose resin and additives were dissolved and mixed in a mixed solvent of methylene chloride and methanol (mixing ratio (mass ratio): methylene chloride:methanol = 9:1) in an amount 20 times the total mass of the crystalline cellulose resin and additives. The solvent was then removed using an evaporator, and the resulting solid was scraped off to obtain a powder (resin composition) for hot melt processing.

(2) Injection Molding Each resin composition obtained above was kneaded and injection molded at various temperatures using a small kneader, and the lowest temperature at which kneading and injection molding were possible was designated as the molding temperature T3 [°C] (maximum temperature during molding) in Table III. Each resin composition was injection molded at the temperature T3 to prepare JIS K7139 scaled test pieces and JIS K7139 rectangular test pieces.

(3) Evaluation The flexural modulus, Charpy impact strength, coloring, and weight average molecular weight of the resin constituting the molded article after molding were measured by the following methods. The results are shown in the lower column of Table III.

3-1: Flexural Modulus A flexural test was carried out in accordance with JIS K7171 using a JIS K7139 scale test piece to determine the flexural modulus.

3-2: Charpy Impact Strength After notching a JIS K7139 rectangular test piece with a Toyo Seiki notching machine, a Charpy impact test was carried out in accordance with JIS K7110 to determine the Charpy impact strength.

3-3: Coloring Coloring was evaluated by placing a JIS K7139 scaled test piece on a white piece of paper, visually observing the coloring, and judging according to the following criteria.
(Evaluation criteria)
◯: Almost no coloring is noticeable.
△: Slight coloring, but no practical problem.
×: Discoloration is evident and there is a problem in practical use.

3-4: Weight average molecular weight after molding A part of the JIS K7139 scale test piece was cut off, and the molecular weight was determined by GPC in the same manner as in the case of the crystalline cellulose resin alone, and expressed as a weight average molecular weight.

[Production of injection molded products 2]
The crystalline cellulose resins in Table I and the additives shown in Table II were combined as shown in Table IV to prepare pellets (resin compositions) for hot melt processing by the following method, and then injection molded to produce hot melt molded products 201 to 206.

(1) Mixing 8 kg of crystalline cellulose resin 100, 50 g of stabilizer 1 ("Irgaphos 168" manufactured by BASF), and 50 g of stabilizer 2 ("Adeka Cizer O-130P" manufactured by ADEKA) were mixed for 5 minutes using a mixer FM40 manufactured by Nippon Coke Co., Ltd. at a jacket temperature of 40°C and 1000 rpm.

After that, 2 kg of additive RAa-9 was added every minute in five 400 g portions while stirring at 1000 rpm. During this time, the internal temperature was maintained at 40-50°C. After the addition of additive RAa-9 was completed, stirring continued at 1000 rpm, and the jacket temperature was raised at 10°C/min. Once it reached 90°C, stirring continued at 1000 rpm for 30 minutes. After that, while stirring at 100 rpm, the jacket temperature was raised to 20°C, and mixing was stopped when the internal temperature reached 30°C. This resulted in a powder mixture containing the above components.

(2) Preparation of Pellets (Resin Composition) The powder obtained above was subjected to a Laboplastomill (manufactured by Toyo Seiki Seisakusho Co., Ltd.) equipped with a twin-screw segment extruder and a cold cutter pelletizer, and operated under the following conditions to prepare pellets.
Rotation speed: 100 rpm
Discharge amount: 150g/min
Kneading temperature: 210℃
Die temperature: 220°C

(3) Injection Molding Using the pellets (resin composition) prepared above, after drying at 80°C for 12 hours, injection molding was carried out under the following conditions to prepare test pieces of hot melt molded product 201 having the same shape as that molded in the above-mentioned Production of Injection Molded Product 1. The injection molding temperature corresponds to the temperature of the resin composition immediately after it comes out of the die through which the resin composition is injected from the kneader into the mold, and is the maximum temperature (T3) during molding.
Injection molding temperature 220℃
Mold temperature: 60°C
Injection molding pressure: 80 MPa

As with the above-mentioned hot melt molded product 201, hot melt molded products 202, 203, 204, and 206 were produced by changing some of the conditions as shown in Table IV. Note that with hot melt molded product 205, mixing during injection molding was not possible, and an injection molded product could not be produced.

In the production of hot melt molded products, the maximum temperature during injection molding is shown in Table IV as T3. For hot melt molded product 206, the maximum temperature during pellet (resin composition) production was higher than T3, so the T3 column in Table IV lists the maximum temperature during processing. This is the maximum temperature during pellet (resin composition) production.

(4) Evaluation The flexural modulus, Charpy impact strength, coloration, and weight average molecular weight of the resin constituting the molded article after molding were measured in the same manner as in the evaluation of the molded article in the above-mentioned Production of Injection Molded Article 1. The results are shown in the lower column of Table IV.

[Manufacturing of fused molded products by fused deposition modeling]
The crystalline cellulose resin in Table I and the additives shown in Table II were combined as shown in Table V, and hot melt molded articles 301 to 305 were produced by the fused deposition modeling method using a 3D printer by the following method.

(1) Preparation of filament (resin composition) A powder was prepared as a mixture of crystalline cellulose resin 100, stabilizer 1, stabilizer 2, and additive RAa-9 in the same manner as in the hot melt molded product 201. The obtained powder was kneaded and extruded in a twin-screw kneader in the same manner as in the hot melt molded product 201, and pulled to a diameter of 1.75 mm with a cold cutter unit, without using a cutter, to prepare a filament (resin composition) for 3D printer molding.

(2) Hot melt molding by 3D printer (fused deposition modeling) The 3D printer molding filament obtained above was supplied to the raw material supply section of the 3D printer Raise3D Pro2 (manufactured by RAISE3D). The 3D printer molding filament is heated and melted in the extrusion head, extruded from the tip nozzle, and fused and laminated. The nozzle temperature (corresponding to the temperature of the resin composition immediately after extrusion from the nozzle) is the maximum temperature (T3) during molding. A test piece of a hot melt molded product 301 having the same shape as those molded in the injection molded product production 1 and 2 was produced by the fused deposition modeling using the above 3D printer. In this case, the x-axis direction was the length direction of the test piece, the y-axis direction was the width direction, and the z-axis was the thickness direction.

(3D printer conditions)
Nozzle temperature: 220°C
Bed temperature: 100°C
Layer pitch: 0.3 mm
Output speed: 50 mm/s

As with the above-mentioned hot melt molded product 301, hot melt molded products 302, 303, and 304 were produced by changing some of the conditions as shown in Table V. Note that hot melt molded product 305 could not be extruded using a 3D printer, and a hot melt molded product could not be produced.

(3) Evaluation The flexural modulus, Charpy impact strength, coloration, and weight average molecular weight of the resin constituting the molded article after molding were measured in the same manner as in the evaluation method for the molded article in the above-mentioned Production of Injection Molded Article 1. The results are shown in the lower column of Table V.

[Melt-spun fiber production]
The crystalline cellulose resins shown in Table I and the additives shown in Table II were combined as shown in Table VI, and hot melt molded articles 401 to 405 were produced as melt-spun fibers using a single-screw melt spinning machine by the following method.

(1) Preparation of pellets (resin composition) A powder was prepared as a mixture of crystalline cellulose resin 100, stabilizer 1, stabilizer 2 and additive RAa-9 in the same manner as in the preparation of the hot melt molded product 201. The obtained powder was kneaded and extruded in a twin-screw kneader in the same manner as in the hot melt molded product 201, and pelletized in a cold cutter pelletizer to prepare pellets.

(2) Melt Spinning The pellets (resin composition) prepared above were melted using a single-screw melt spinning machine at a melter temperature of 210°C and extruded (spun) at a discharge rate of 5.9 g/min through a die having six die holes of 0.23 mmφ x 0.30 mmL and a pack temperature of 220°C. The pack temperature corresponds to the temperature of the resin composition immediately after being extruded from the die holes and is the maximum temperature (T3) during molding.

The spun yarn was cooled by chimney air at 25°C, oiled, and converged. It was then taken up by a first godet roller rotating at 450 m/min, passed through a second godet roller rotating at the same speed as the first godet roller, and wound on a winder rotating at a speed that provided a winding tension of 0.1 cN/dtex. The resulting fiber was called hot-melt molded product 401.

Similar to the above-mentioned hot melt molded product 401, hot melt molded products 402, 403, and 404 were produced by changing some of the conditions as shown in Table VI. Note that with hot melt molded product 405, spinning from the spinneret was not possible, and a hot melt molded product (fiber) could not be produced.

(3) Evaluation The mechanical properties of the hot melt molded articles (fibers) obtained above were evaluated by the strength and elongation at break measured in a tensile test carried out in accordance with JIS L1015 as follows. The results are shown in the lower column of Table VI.

(Strength and elongation)
Tensilon UCT-100 manufactured by Orientec Co., Ltd. was used to carry out a tensile test under the conditions of a sample length of 20 cm and a tensile speed of 20 cm/min, and the stress at the point showing the maximum load was taken as the fiber strength (cN/dtex). The elongation at break was taken as the fiber elongation (%).

The hot-melt molded product 401 had extremely good spinnability, with no broken yarns observed. The resulting fiber had a strength of 1.0 cN/dtex and an elongation of 38%. Furthermore, the single yarn fineness, evaluated in accordance with JIS L1095, was 21.9 dtex and the U% was 0.7%. An attempt was made to knit a fabric using the resulting fiber (hot-melt molded product 401) on a cylindrical knitting machine (MR1 type cylindrical knitting machine, 27 gauge, manufactured by Maruzen Sangyo Co., Ltd.), and the knitting was good, resulting in a knitted fabric with a soft texture.

The above results show that the resin composition of the present invention has excellent hot melt moldability and retains the good physical properties of the cellulose resin in the resulting hot melt molded products.

The present invention provides a resin composition containing a cellulose resin that has excellent hot-melt moldability and is capable of retaining the good physical properties of the cellulose resin in the resulting hot-melt molded product. It also provides a hot-melt molded product that retains the good physical properties of the cellulose resin, and a molding method for the same.

Claims (6)

A resin composition for hot melt molding containing a crystalline cellulose resin as a main component,
Contains an additive that satisfies the following formula (1):
the additive is any one of the following compounds RAa-1, RAa -9, and RB-3,
The resin composition is characterized in that the crystalline cellulose resin is a crystalline cellulose ester resin, in which the degree of substitution of hydrogen atoms for hydroxy groups in the crystalline cellulose ester resin is 2.7 or more, and the degree of substitution of acetyl groups in the crystalline cellulose ester resin is 2.7 or more.
Formula (1) T2≦T1×0.93
In formula (1), T2 represents the melting point [°C] of a mixture in which 10 parts by mass of the additive is added to 90 parts by mass of the crystalline cellulose resin, and T1 represents the melting point [°C] of the crystalline cellulose resin alone.
The resin composition according to claim 1, wherein the difference between T1 and T2 is 25°C or more. The resin composition according to claim 1 or 2, wherein the additive satisfies the following (i), (ii), or (iii) in the following formula (2):
(i) Vu/V1<1.0 and χ<3
(ii) 1.0≦Vu/V1<1.5 and χ<6
(iii) 1.5≦Vu/V1 and χ<8
Formula (2) 1/Tm-1/Tm ⁰ = (R/△Hu)×(Vu/V1)×(ν ₁ −χν ₁ ² )
In formula (2), the symbols have the following meanings.
Tm: melting point (absolute temperature) of a mixture obtained by adding 10 parts by mass of the additive to 90 parts by mass of the crystalline cellulose resin
Tm ⁰ : melting point (absolute temperature) of the crystalline cellulose resin alone
R: gas constant ΔHu: heat of fusion per mole of repeating unit forming the crystalline cellulose resin V1: molar volume of the additive Vu: molar volume of repeating unit forming the crystalline cellulose resin ν ₁ : volume fraction of the additive in a mixture obtained by adding 10 parts by mass of the additive to 90 parts by mass of the crystalline cellulose resin χ: parameter indicating the interaction between the crystalline cellulose resin and the additive A hot-melt molded product made from the resin composition described in any one of claims 1 to 3. A molding method for hot melt molding the resin composition according to any one of claims 1 to 3,
The molding method comprises carrying out the hot melt molding under conditions that satisfy the following formula (3):
Formula (3) T3≦T1×0.75+20
In formula (3), T3 represents the maximum temperature [°C] of the resin composition during hot melt molding. The molding method according to claim 5, which is injection molding, extrusion molding, or fused deposition modeling.