Resin composition

Abstract

To provide a resin composition that can provide a molding having excellent heat resistance and also excelling in flexibility (maximum point elongation in a bending test).SOLUTION: A resin composition has thermosetting resin and polyethylene glycol-modified lignin. Since the resin composition has thermosetting resin and polyethylene glycol-modified lignin, it can provide a molding having excellent heat resistance and also excelling in flexibility (maximum point elongation in a bending test).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a resin composition, and more particularly to a resin composition containing a thermosetting resin. [Background technology]

[0002] 2. Description of the Related Art Thermosetting resins have been widely used in various industrial fields, such as electrical parts, automobile parts, building materials, and daily necessities.

[0003] Such thermosetting resins are required to have improved physical properties, such as the mechanical properties (strength, etc.) of the molded product, heat resistance, electrical insulation, etc., depending on the application. In order to satisfy the required physical properties, the addition of various additives to thermosetting resins has been considered.

[0004] Moreover, in recent years, from the viewpoint of environmental conservation, there has been a demand for effective use of plant-derived materials as additives to be added to thermosetting resins. Specifically, for example, a lignin-added thermosetting resin containing a thermosetting resin and herbaceous lignin has been proposed (see, for example, Patent Document 1).

[0005] Such a lignin-added thermosetting resin can ensure excellent mechanical properties, heat resistance, and electrical insulation.

[0006] In recent years, in order to further improve the physical properties, it has been proposed to use modified lignin as the lignin to be mixed with the thermosetting resin. More specifically, a resin composition containing a thermosetting resin and lignin modified with a carboxylic acid has been proposed (for example, see Patent Document 2). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2012-082255 A [Patent Document 2] International Publication No. WO2015 / 178103 Summary of the Invention [Problem to be solved by the invention]

[0008] On the other hand, for thermosetting resins, depending on the application, there are cases where further improvement in heat resistance and improvement in flexibility are required.

[0009] The present invention relates to a resin composition capable of giving a molded article having excellent heat resistance and flexibility (maximum elongation in a bending test). [Means for solving the problem]

[0010] The present invention [1] includes a resin composition containing a thermosetting resin and lignin modified with polyethylene glycol.

[0011] The present invention [2] includes the resin composition according to the above [1], in which the lignin is a coniferous lignin.

[0012] The present invention [3] includes the resin composition according to the above [1] or [2], in which the thermosetting resin is a novolac-type phenolic resin.

[0013] The present invention [4] includes the resin composition according to any one of the above [1] to [3], in which the content of the lignin modified with polyethylene glycol is 100 parts by mass or more per 100 parts by mass of the thermosetting resin. Effect of the Invention

[0014] The resin composition of the present invention contains a thermosetting resin and lignin modified with polyethylene glycol. Therefore, the resin composition of the present invention can provide a molded product having excellent heat resistance and flexibility (maximum elongation in a bending test). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The resin composition of the present invention contains a thermosetting resin and lignin modified with polyethylene glycol (PEG) (hereinafter, may be referred to as PEG-modified lignin).

[0016] The thermosetting resin is not particularly limited, and examples thereof include known thermosetting resins, such as phenolic resins (novolac-type phenolic resins, resol-type phenolic resins, etc.), epoxy resins, melamine resins, urea resins, unsaturated polyester resins, urethane resins, and benzoguanamine resins.

[0017] These thermosetting resins can be used alone or in combination of two or more kinds.

[0018] As the thermosetting resin, from the viewpoint of improving flexibility (maximum elongation in a bending test), preferably, a phenol resin is used, and more preferably, a novolac type phenol resin is used.

[0019] In addition, a curing agent can be blended into the resin composition depending on the type of thermosetting resin. More specifically, for example, when a phenolic resin is used as the thermosetting resin, a phenolic resin curing agent can be blended into the resin composition.

[0020] The phenol resin curing agent is not particularly limited, and any known curing agent can be used, such as hexamethylenetetramine, methylolmelamine, and methylolurea.

[0021] These phenolic resin curing agents can be used alone or in combination of two or more kinds.

[0022] As the phenol resin curing agent, preferably, hexamethylenetetramine is used.

[0023] The mixing ratio of the phenolic resin curing agent is appropriately set depending on the purpose and application.

[0024] In the PEG-modified lignin, the polyethylene glycol (PEG) is appropriately selected depending on the physical properties required for the resin composition.

[0025] The number average molecular weight of polyethylene glycol, from the viewpoint of achieving both flexibility (maximum elongation in a bending test) and impact resistance, is, for example, 100 or more, preferably 200 or more, more preferably 300 or more, and even more preferably 400 or more, and for example, 1000 or less, preferably 900 or less, more preferably 800 or less, and even more preferably 600 or less.

[0026] The number average molecular weight can be determined as a polyethylene glycol-equivalent molecular weight by a known gel permeation chromatography method.

[0027] In PEG-modified lignin, lignin is a polymeric phenolic compound consisting of a basic skeleton such as guaiacyl lignin (G type), syringyl lignin (S type), and p-hydroxyphenyl lignin (H type), and is found in plants as a natural product (natural lignin).

[0028] Known examples of natural lignin extracted industrially include soda lignin, sulfite lignin, and kraft lignin, which are contained in the waste liquid (black liquor) discharged when pulp is produced from raw plant material (lignocellulose) by the soda process, sulfite process, kraft process, or other methods.

[0029] Specific examples of lignin include lignin derived from woody plants and lignin derived from herbaceous plants.

[0030] Examples of lignin derived from woody plants include coniferous lignin contained in coniferous trees (such as cedar), and broadleaf lignin contained in broadleaf trees.

[0031] Lignin derived from woody plants does not contain the basic H-type structure.

[0032] More specifically, among lignins derived from woody plants, coniferous lignin does not contain an S-type basic skeleton, but has a G-type basic skeleton, while hardwood lignin has both a G-type basic skeleton and an S-type basic skeleton.

[0033] Examples of lignins derived from herbaceous plants include rice lignins contained in grass plants (wheat straw, rice straw, corn, bamboo, etc.).

[0034] Lignin derived from herbaceous plants has all the basic skeletons of H-type, G-type and S-type.

[0035] These lignins can be used alone or in combination of two or more kinds.

[0036] From the viewpoint of homogeneity of the PEG-modified lignin, the lignin is preferably a woody plant-derived lignin that does not contain an H-type basic skeleton, more preferably a coniferous lignin that does not contain an S-type basic skeleton and has a G-type basic skeleton, and particularly preferably a coniferous lignin derived from cedar.

[0037] The PEG-modified lignin is not particularly limited, but can be produced, for example, in accordance with the method described in JP 2017-197517 A.

[0038] More specifically, for example, a plant material (lignocellulose) serving as the raw material for lignin can be digested with polyethylene glycol to obtain PEG-modified lignin.

[0039] The digestion method is not particularly limited, but for example, a plant material that is the raw material for lignin, polyethylene glycol, and an inorganic acid (for example, hydrochloric acid, sulfuric acid, etc.) as an acid catalyst are mixed and reacted.

[0040] The mixing ratio of polyethylene glycol per 100 parts by mass of the plant material that is the raw material for lignin is, for example, 200 parts by mass or more, preferably 300 parts by mass or more, and for example, 1,000 parts by mass or less, preferably 600 parts by mass or less.

[0041] The mixing ratio of the inorganic acid is, for example, 0.1 part by mass or more, preferably 0.2 part by mass or more, and for example, 2 parts by mass or less, preferably 1 part by mass or less, per 100 parts by mass of polyethylene glycol (100% conversion).

[0042] The reaction conditions are as follows: under normal pressure, the reaction temperature is, for example, 120° C. or more, preferably 130° C. or more, and for example, 180° C. or less, preferably 150° C. or less, and the reaction time is, for example, 60 minutes or more, and for example, 240 minutes or less, preferably 120 minutes or less.

[0043] After the reaction is completed, a known alkali (eg, ammonia, sodium hydroxide, etc.) is added in an appropriate ratio to adjust the pH, and the PEG-modified lignin is extracted into the solution.

[0044] The adjusted pH is, for example, 8 or more, preferably 10 or more, more preferably 10.5 or more, and for example, 14 or less.

[0045] By such a method, pulp is obtained as a solid component, and PEG-modified lignin is obtained as a solution component (pulp waste liquor).

[0046] Next, in this method, the solid component (pulp) is separated from the reaction product by a known separation method such as filtration, pressing, or centrifugation, and the solution component (pulp waste liquor) is recovered.

[0047] Furthermore, in this method, if necessary, the solid component (pulp) can be washed and the solution (PEG-modified lignin) impregnated into the solid component can be recovered.

[0048] In this method, an inorganic acid (eg, hydrochloric acid, sulfuric acid, etc.) is then added to adjust the pH to precipitate and cause the PEG-modified lignin to precipitate.

[0049] The pH after adjustment is, for example, 1.5 or more, and for example, 5 or less, preferably 3 or less, and more preferably 2 or less.

[0050] This allows the PEG-modified lignin to precipitate, and the resulting precipitate can be collected by a known method such as filtration, pressing, or centrifugation to obtain the PEG-modified lignin as a solid content.

[0051] Then, the thermosetting resin and the PEG-modified lignin are mixed (kneaded) to obtain a resin composition.

[0052] From the viewpoint of improving heat resistance and flexibility (maximum elongation in a bending test), the blending ratio (content ratio) of these is, based on the mass of the solid content, for example, 10 parts by mass or more, preferably 50 parts by mass or more, and more preferably 100 parts by mass or more of PEG-modified lignin per 100 parts by mass of thermosetting resin, and for example, 1,000 parts by mass or less, preferably 500 parts by mass or less, more preferably 400 parts by mass or less, even more preferably 300 parts by mass or less, and particularly preferably 200 parts by mass or less.

[0053] From the viewpoint of heat resistance, the amount of the PEG-modified lignin is more preferably 150 parts by mass or more, even more preferably more than 150 parts by mass, and particularly preferably 180 parts by mass or more, relative to 100 parts by mass of the thermosetting resin, and is, for example, 1000 parts by mass or less, preferably 500 parts by mass or less, and particularly preferably 250 parts by mass or less.

[0054] Also, from the viewpoint of flexibility, it is more preferable that the amount of PEG-modified lignin is 150 parts by mass or less, even more preferably less than 150 parts by mass, and particularly preferably 120 parts by mass or less, relative to 100 parts by mass of the thermosetting resin, and for example, 10 parts by mass or more, preferably 50 parts by mass or more, and particularly preferably 80 parts by mass or more.

[0055] The kneading method is not particularly limited, and for example, a known kneader such as a single screw extruder, a multi-screw extruder, a roll kneader, a kneader, a Henschel mixer, or a Banbury mixer can be used.

[0056] The kneading conditions are such that the kneading temperature is 80° C. or more, preferably 90° C. or more, more preferably 100° C. or more, and 180° C. or less, preferably 170° C. or less, more preferably 160° C. or less. The kneading time is, for example, 3 minutes or more, preferably 5 minutes or more, and for example, 30 minutes or less, preferably 20 minutes or less.

[0057] This results in a resin composition containing a thermosetting resin and a PEG-modified lignin.

[0058] In the resin composition, the content of the PEG-modified lignin is, relative to 100 parts by mass of the thermosetting resin, for example, 10 parts by mass or more, preferably 50 parts by mass or more, more preferably 100 parts by mass or more, and for example, 1,000 parts by mass or less, preferably 500 parts by mass or less, more preferably 400 parts by mass or less, even more preferably 300 parts by mass or less, and particularly preferably 200 parts by mass or less.

[0059] From the viewpoint of heat resistance, the amount of the PEG-modified lignin is more preferably 150 parts by mass or more, even more preferably more than 150 parts by mass, and particularly preferably 180 parts by mass or more, relative to 100 parts by mass of the thermosetting resin, and is, for example, 1000 parts by mass or less, preferably 500 parts by mass or less, and particularly preferably 250 parts by mass or less.

[0060] Also, from the viewpoint of flexibility, it is more preferable that the amount of PEG-modified lignin is 150 parts by mass or less, even more preferably less than 150 parts by mass, and particularly preferably 120 parts by mass or less, relative to 100 parts by mass of the thermosetting resin, and for example, 10 parts by mass or more, preferably 50 parts by mass or more, and particularly preferably 80 parts by mass or more.

[0061] In addition, the resin composition may contain additives in addition to the thermosetting resin and the PEG-modified lignin.

[0062] Examples of additives include known additives added to thermosetting resin compositions, such as fillers (wood flour, pulp, glass fiber, etc.), colorants, plasticizers, stabilizers, and release agents (metal soaps such as zinc stearate, etc.).

[0063] These additives can be used alone or in combination of two or more kinds.

[0064] As the additive, preferably, a filler is used, and more preferably, wood flour and glass fiber are used.

[0065] From the viewpoint of improving mechanical properties and water resistance, glass fiber is more preferable, and from the viewpoint of improving heat resistance and electrical insulation, wood flour is more preferable.

[0066] From the viewpoint of improving various physical properties in a well-balanced manner, more preferably, wood flour and glass fiber are used in combination. When wood flour and glass fiber are used in combination, their mixing ratio is not particularly limited, and the glass fiber is, for example, 20 parts by mass or more, preferably 50 parts by mass or more, and for example, 300 parts by mass or less, preferably 200 parts by mass or less, per 100 parts by mass of wood flour.

[0067] The content of the additives is appropriately set depending on the purpose and application, within a range that does not impair the excellent effects of the present invention.

[0068] For example, when a filler is added, the mixing ratio of the filler per 100 parts by mass of the thermosetting resin is, for example, 10 parts by mass or more, preferably 20 parts by mass or more, and for example, 300 parts by mass or less, preferably 200 parts by mass or less.

[0069] In addition, the additive may be added to the thermosetting resin and / or the PEG-modified lignin in advance, may be added simultaneously when the thermosetting resin and the PEG-modified lignin are blended, or may be added to a mixture of the thermosetting resin and the PEG-modified lignin.

[0070] Such a resin composition contains a thermosetting resin and lignin modified with polyethylene glycol, and therefore, the resin composition can provide a molded product having excellent heat resistance and flexibility (maximum elongation in a bending test).

[0071] Furthermore, such a resin composition can give molded products that are excellent in various physical properties such as mechanical properties (such as bending properties) other than heat resistance and flexibility (maximum elongation in a bending test), impact resistance, and electrical insulation.

[0072] Therefore, the above resin composition is used for producing a molded article.

[0073] More specifically, the above-mentioned resin composition is molded by a known molding method for thermosetting resins, such as transfer molding or compression molding.

[0074] The molding conditions are such that the molding temperature is, for example, 120° C. or more, preferably 150° C. or more, and for example, 250° C. or less, preferably 200° C. or less. The molding time is, for example, 1 minute or more, preferably 5 minutes or more, and for example, 30 minutes or less, preferably 15 minutes or less.

[0075] In this method, the resulting molded product can be cured, if necessary.

[0076] The curing conditions are such that the curing temperature is, for example, 120° C. or more, preferably 150° C. or more, and for example, 250° C. or less, preferably 200° C. or less. The curing time is, for example, 30 minutes or more, preferably 60 minutes or more, and for example, 300 minutes or less, preferably 150 minutes or less.

[0077] This allows the production of molded products with excellent heat resistance and flexibility (maximum elongation in bending tests), which can be used in a wide range of industrial fields, including electrical parts, automobile parts, building materials, and daily necessities. EXAMPLES

[0078] Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited to the following examples. Note that "parts" and "%" are based on mass unless otherwise specified. In addition, the specific numerical values ​​of the blending ratio (content ratio), physical property values, parameters, etc. used in the following description can be replaced with the upper limit value (numerical value defined as "less than or equal to" or "less than") or lower limit value (numerical value defined as "more than or equal to" or "exceeding") of the corresponding blending ratio (content ratio), physical property values, parameters, etc. described in the above "Form for carrying out the invention".

[0079] Production Example 1 (Mn200-PEG modified lignin) Lignin modified with polyethylene glycol having a number average molecular weight of 200 (hereinafter, Mn200-PEG-modified lignin) was produced by the following method.

[0080] That is, 230 parts by mass of commercially available polyethylene glycol (PEG200) having a number average molecular weight of 200 and 0.69 parts by mass of sulfuric acid as an acid catalyst (0.3 part by mass relative to 100 parts by mass of PEG200) were placed in a reaction vessel and stirred.

[0081] Next, 46 parts by mass of bone-dried cedar wood flour was added to the reaction vessel, the temperature was raised to 140° C. under normal pressure, and the mixture was reacted for 90 minutes with stirring.

[0082] Next, the reaction vessel was cooled, and after it was confirmed that the temperature had reached 40° C. or lower, 280 parts by mass of sodium hydroxide (0.2 mol / L) was added and stirred for 30 minutes.

[0083] Next, the resulting solid component (pulp) was removed using a filter press, and the solution component was recovered.

[0084] Next, sulfuric acid was added to the obtained solution component to adjust the pH to 2.0, thereby obtaining a suspension of Mn200-PEG-modified lignin.

[0085] The Mn200-PEG modified lignin was then collected by centrifugation.

[0086] Production Example 2 (Mn400-PEG modified lignin) An Mn400-PEG-modified lignin was obtained in the same manner as in Production Example 1, except that polyethylene glycol having a number average molecular weight of 400 (hereinafter, Mn400-PEG) was used instead of polyethylene glycol having a number average molecular weight of 200.

[0087] Production Example 3 (Mn600-PEG modified lignin) An Mn600-PEG-modified lignin was obtained in the same manner as in Production Example 1, except that polyethylene glycol having a number average molecular weight of 600 (hereinafter, Mn600-PEG) was used instead of polyethylene glycol having a number average molecular weight of 200.

[0088] Production Example 4 (Unmodified Lignin) The alkaline pulp wastewater (black liquor) of wheat straw was neutralized and filtered to obtain unmodified lignin as a solid fraction.

[0089] Production Example 5 (Acetic Acid Modified Lignin) 100 parts by mass of corn stover was mixed with 1000 parts by mass of 95% acetic acid and 3 parts by mass of sulfuric acid, and reacted under reflux for 4 hours. After the reaction, the pulp was removed by filtration, and the pulp waste liquid was recovered. Next, the acetic acid in the pulp waste liquid was removed using a rotary evaporator, and the liquid was concentrated to 1 / 10 in volume, after which 10 times the amount (by mass) of the concentrated liquid was added and filtered to obtain acetic acid-modified lignin as a solid content.

[0090] Reference examples 1~3, Examples 4 to 13 and Comparative Examples 1 to 5 According to the formulations shown in Tables 1 and 2, novolac-type phenolic resin (manufactured by Asahi Organic Chemicals Co., Ltd.), lignin from Production Examples 1 to 5, wood flour (manufactured by Asahi Organic Chemicals Co., Ltd.) as a filler, hexamethylenetetramine (manufactured by Lignite Corporation) as a curing agent, and zinc stearate (manufactured by Wako Pure Chemical Industries, Ltd.) as a release agent were sequentially blended and kneaded with two heated rolls at 100°C for 5 minutes to obtain a resin composition.

[0091] <Evaluation> Each reference example, The resin compositions obtained in each Example and Comparative Example were subjected to transfer molding at 170° C. for 15 minutes. , each reference example In each example, the specimens were further heat-cured at 180° C. for 2 hours to obtain rectangular test pieces for bending tests, U-notch test pieces for Charpy impact tests, and 75 mmφ disk-shaped test pieces for other tests. The obtained molded pieces were evaluated by the following methods.

[0092] (1) Glass transition temperature (heat resistance, Tg) The solid dynamic viscoelasticity was measured using Rheogel-E4000 (manufactured by UBM) (frequency 1 Hz, heating rate 2°C / min). The peak temperature of the obtained tan δ curve was determined as the glass transition temperature (Tg).

[0093] (2) Maximum elongation In accordance with JIS K6911 (1995), a three-point bending test was performed at a crosshead speed of 3 mm / min and a span of 100 mm to measure the maximum elongation. The maximum elongation is the strain (maximum elongation) when the specimen is bent until it breaks, and was calculated using the following formula:

[0094] Maximum point elongation (ε)=[6T / L 2 ] × ΔL (T: sample thickness, L: support distance, ΔL: bending deflection)

[0095] [Table 1]

[0096] [Table 2]

[0097] <Consideration> Each reference example and The molded articles obtained using the resin compositions of each Example are superior in heat resistance (glass transition temperature) and flexibility (maximum elongation in bending test) to the molded articles obtained using the resin compositions of each Comparative Example. Reference Examples 1 to 3 and Example 4 As shown in 13, the flexibility (maximum elongation in a bending test) is improved as the number average molecular weight of PEG in the PEG-modified lignin is relatively higher.

[0098] Furthermore, as shown in Comparative Examples 2 and 3, generally, when the amount of lignin in a resin composition increases, the heat resistance (glass transition temperature) decreases, and the molded product becomes brittle and the flexibility (maximum elongation in a bending test) decreases. Reference Examples 1 to 3 and Example 4 As shown in Figures 1 to 13, when the PEG-modified lignin is used, even if the amount of the PEG-modified lignin in the resin composition is increased, the molded product does not become embrittled, and the flexibility (maximum elongation in a bending test) is improved, and further, the heat resistance (glass transition temperature) is also improved.

[0099] <Evaluation 2> (3) Flexural strength and flexural modulus In accordance with JIS K6911 (1995), a three-point bending test was performed at a crosshead speed of 3 mm / min and a span of 100 mm to measure the bending strength and bending modulus.

[0100] (4) Charpy impact strength The Charpy impact strength was measured using an impact tester (manufactured by Toyo Seiki Seisakusho) in accordance with JIS K6911 (1995).

[0101] (5) Dielectric constant The dielectric constant at a frequency of 1 GHz was measured by the capacitance method using an impedance analyzer E4991A (Agilent Technologies).

[0102] [Table 3]

[0103] [Table 4]

[0104] <Consideration> Each reference example and The molded articles obtained using the resin compositions of each Example are superior in various physical properties (mechanical properties (e.g., bending properties), impact resistance, electrical insulation, etc.) other than heat resistance (glass transition temperature) and flexibility (maximum elongation in bending test) compared to the molded article obtained using the resin composition of Comparative Example 1. In particular, Reference Examples 1 to 3 and Example 4 As seen from References 1 to 13, the higher the number average molecular weight of PEG in the PEG-modified lignin, the more excellent the various physical properties are.

Claims

1. A thermosetting resin; Polyethylene glycol modified lignin and Contains the thermosetting resin is a novolac phenolic resin, A resin composition, characterized in that the polyethylene glycol has a number average molecular weight of 400 or more.

2. The resin composition according to claim 1 , wherein the lignin is a softwood lignin.

3. For 100 parts by mass of thermosetting resin, The resin composition according to claim 1 or 2, wherein the content of the lignin modified with polyethylene glycol is 100 parts by mass or more.

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