JP2010023275A - Polycarbonate resin/cellulose fiber laminate and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a composite material with high transparency, high elasticity, a low linear expansion coefficient and good balance of characteristics such as impact resistance, and also good in productivity by making a laminate of a polycarbonate resin layer and a cellulose fiber layer. <P>SOLUTION: This laminate comprising a polycarbonate resin layer and a cellulose fiber layer comprises a polycarbonate resin layer whose thickness is ≥1.4 time to that of the cellulose fiber layer, and is produced by laminating the cellulose fiber layer and the polycarbonate resin layer and fusing the laminate by heating. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polycarbonate resin / cellulose fiber laminate having a polycarbonate resin layer and a cellulose fiber layer, and in particular, by integrating and integrating the polycarbonate resin layer and the cellulose fiber layer, highly transparent, highly elastic, low wire The present invention relates to a polycarbonate resin / cellulose fiber laminate that realizes a composite that has a good balance of properties such as impact resistance and expansion coefficient and good productivity. The present invention also relates to a method for producing such a polycarbonate resin / cellulose fiber laminate.

  Conventionally, transparent, low linear expansion coefficient, and high elasticity composites made by impregnating cellulose nanofiber sheets with polycarbonate resin have been provided. However, it is difficult to control the impregnation state and the production yield of the composite is poor. there were.

  In addition, for the purpose of improving transparency, a method is known in which polystyrene film or polyethylene terephthalate film is heat-sealed with a cellulose nanofiber sheet. However, when a polystyrene film is used, there is a problem in mechanical properties and a low linear expansion coefficient although the obtained composite has high transparency. In other words, polystyrene has a poor affinity with cellulose due to its structure, and the bonding at the interface with cellulose is weak, so the adhesion when stress is applied is weak, so the characteristics of cellulose are not reflected and linear expansion There was a concern that the coefficient would be high. Also, when polyethylene terephthalate film is used, when heat-sealing to cellulose nanofiber sheet, it will crystallize at high temperature, and high transparency cannot be maintained. There is a concern that the adhesion will deteriorate.

Patent Document 1 describes that the surface of a cellulose fiber aggregate is coated with an organic polymer material to obtain a transparent composite material having a low coefficient of linear expansion, and there is also an example of a polycarbonate resin as a material used for coating. However, in this composite material, a thinner coating layer is better for maintaining the physical properties of cellulose. However, it is expected that physical properties such as impact resistance and flexibility cannot be obtained with a composite material having a thin coating layer.
JP 2008-24778 A

  The present invention solves the above-mentioned conventional problems, and by making a laminate of a polycarbonate resin layer and a cellulose fiber layer, it is highly transparent, highly elastic, has a low coefficient of linear expansion, and has a good balance of properties such as impact resistance. The purpose is to provide a composite with good productivity.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have a laminated structure of a polycarbonate resin layer and a cellulose fiber layer, and the thickness of the polycarbonate resin layer is increased to a predetermined value or more with respect to the thickness of the cellulose fiber layer. Thus, the inventors have found that the above problems can be solved, and have reached the present invention.

  The gist of the present invention is as follows.

[1] A laminate comprising a polycarbonate resin layer and a cellulose fiber layer, wherein the polycarbonate resin layer has a thickness of 1.4 times or more of the thickness of the cellulose fiber layer.

[2] The polycarbonate resin / cellulose fiber laminate according to [1], wherein the cellulose fiber layer is sandwiched between polycarbonate resin layers.

[3] The polycarbonate resin / cellulose fiber laminate according to [1] or [2], wherein an average fiber diameter of the cellulose fibers constituting the cellulose fiber layer is 200 nm or less.

[4] The polycarbonate resin / cellulose fiber laminate according to any one of [1] to [3], wherein the cellulose fiber layer has a porosity of 35 vol% or less.

[5] The polycarbonate resin / cellulose fiber laminate according to any one of [1] to [4], wherein the cellulose fibers constituting the cellulose fiber layer are chemically modified.

[6] The method for producing a polycarbonate resin / cellulose fiber laminate according to any one of [1] to [5], including a step of laminating a cellulose fiber layer and a polycarbonate resin layer and heat-sealing them.

[7] The method for producing a polycarbonate resin / cellulose fiber laminate according to [6], in which the cellulose fiber layer and the polycarbonate resin layer are laminated and heat-sealed after the primer treatment is performed on the laminated surface of the cellulose fiber layer.

[8] The method for producing a polycarbonate resin / cellulose fiber laminate according to [6] or [7], in which after the cellulose fiber is chemically modified, the cellulose fiber layer and the polycarbonate resin layer are laminated and heat-sealed.

[9] The method for producing a polycarbonate resin / cellulose fiber laminate according to any one of [6] to [8], wherein heat fusion is performed under reduced pressure.

  According to the present invention, a laminated structure of a polycarbonate resin layer and a cellulose fiber layer is used regardless of the conventional impregnation or coating of the polycarbonate resin, and the thickness of the polycarbonate resin layer is greater than a predetermined value with respect to the thickness of the cellulose fiber layer. By doing so, it is possible to provide a composite having high transparency, high elasticity, a low coefficient of linear expansion, a good balance of properties such as impact resistance, and excellent productivity.

  Hereinafter, embodiments of the polycarbonate resin / cellulose fiber laminate and the method for producing the same according to the present invention will be described in detail. Is not limited to these contents.

[Polycarbonate resin / cellulose fiber laminate]
The polycarbonate resin / cellulose fiber laminate of the present invention comprises a polycarbonate resin layer and a cellulose fiber layer, wherein the thickness of the polycarbonate resin layer is 1.4 times or more with respect to the thickness of the cellulose fiber layer. .

{Polycarbonate resin layer}
As the polycarbonate resin layer, a film of polycarbonate resin can be used, and examples of the polycarbonate resin include aromatic polycarbonate resins and aliphatic (including alicyclic) polycarbonate resins.

  As an aromatic polycarbonate resin, it is produced by reacting one or more bisphenols that can contain polyhydric phenols having three or more valences as copolymerization components with carbonate esters such as bisalkyl carbonate, bisaryl carbonate, and phosgene. In order to make aromatic polyester carbonates as required, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid or derivatives thereof (for example, aromatic dicarboxylic acid diesters and aromatic dicarboxylic acids) Acid chlorides) may be used.

  Examples of the bisphenols include bisphenol A, bisphenol C, bisphenol E, bisphenol F, bisphenol M, bisphenol P, bisphenol S, and bisphenol Z (for the abbreviations refer to the Aldrich reagent catalog). (Where the central carbon participates in the cyclohexane ring) is preferred, and bisphenol A is particularly preferred.

  Examples of copolymerizable trihydric phenols include 1,1,1- (4-hydroxyphenyl) ethane and phloroglucinol.

  Examples of the aliphatic polycarbonate resin include a copolymer produced by a reaction between an aliphatic diol component and / or an alicyclic diol component and a carbonic ester such as bisalkyl carbonate and phosgene. Examples of the alicyclic diol include cyclohexanedimethanol and isosorbite.

  There is no particular limitation on the molecular weight of the polycarbonate resin, and the weight average molecular weight Mw measured by GPC (gel permeation chromatography) is usually preferably 10,000 to 500,000. From the viewpoint, the weight average molecular weight Mw is preferably 15,000 to 200,000, more preferably 20,000 to 100,000.

  Moreover, the glass transition point Tg of polycarbonate resin is 120-190 degreeC normally, Preferably it is 130-180 degreeC from a viewpoint of heat resistance and melt fluidity, More preferably, it is 140-180 degreeC.

  The polycarbonate resin may be used alone or in combination of two or more as a polymer blend.

  The thickness of the polycarbonate resin film used for forming the polycarbonate resin layer of the polycarbonate resin / cellulose fiber laminate of the present invention is not particularly limited, but if it is excessively thin, the polycarbonate resin layer / Since it may be difficult to satisfy the thickness ratio of the cellulose fiber layer, it is usually 14 μm or more, preferably 50 μm or more, and usually 3 mm or less, preferably 1.5 mm or less.

{Cellulose fiber layer}
The cellulose fiber layer is a layer formed from a nonwoven fabric mainly composed of cellulose fibers (hereinafter referred to as “cellulose nonwoven fabric”), and is an aggregate of cellulose fibers. The cellulose nonwoven fabric can be obtained by a method of forming a cellulose dispersion by papermaking or coating, or a method of drying a gel film.

<Thickness>
The thickness of the cellulose nonwoven fabric forming the cellulose fiber layer is not particularly limited, but is preferably 10 μm or more and 1 mm or less, more preferably 20 μm or more and 500 μm or less, and particularly preferably 30 μm or more and 300 μm or less. The thickness of the cellulose nonwoven fabric is preferably 50 μm or more from the viewpoint of production stability and strength, and is preferably 250 μm or less from the viewpoint of productivity and uniformity.
In addition, the thickness of this cellulose nonwoven fabric is calculated | required according to the measuring method of the thickness of a cellulose nonwoven fabric in the term of the description of the porosity of a cellulose nonwoven fabric.

<Fiber diameter>
The fiber diameter of the cellulose fiber forming the cellulose fiber layer is preferably thin. Specifically, it is preferable not to include those having a diameter of 1500 nm or more, more preferably not including fibers having a diameter of 1000 nm or more, particularly preferably not including fibers having a diameter of 500 nm or more. It is preferable. If the nonwoven fabric does not contain a fiber having a fiber diameter of 1500 nm or more, when it is combined with a resin, a nonwoven fabric with high transparency and low linear expansion coefficient can be obtained.
In addition, the fiber diameter of a cellulose fiber can be confirmed by SEM observation.

  Moreover, it is preferable that the cellulose fiber diameter of the cellulose nonwoven fabric observed from SEM is 4 to 200 nm on average. If the average fiber diameter of the cellulose fibers exceeds 200 nm, it is not preferable because it approaches the wavelength of visible light and refraction of visible light tends to occur at the interface with the matrix material, resulting in a decrease in transparency. Further, fibers having a fiber diameter of less than 4 nm cannot be substantially produced. From the viewpoint of transparency, the average fiber diameter of the cellulose fibers is more preferably 4 to 100 nm.

<Fiber length>
Although it does not specifically limit about the fiber length of a cellulose fiber, 100 nm or more is preferable on average. If the average length of the cellulose fiber is shorter than 100 nm, the strength may be insufficient.

<Raw material>
Examples of the raw material of the cellulose nonwoven fabric include woody materials such as conifers and hardwoods, bacterial cellulose produced by bacteria, cotton such as cotton linter and cotton lint, seaweeds such as valonia and clover, and sea squirt sac. These natural celluloses are preferable because of their high crystallinity and low linear expansion. Bacterial cellulose is easily obtained with a fine fiber diameter, but it is not preferable because it has a flat crystal structure in the lateral direction and forms a branched fiber form, which easily causes light scattering. Cotton is also preferable in that it can be easily obtained with a fine fiber diameter, but it is not economically preferable because the production amount is low compared to wood. On the other hand, woody materials such as conifers and broad-leaved trees have a very fine microfibril diameter of about 4 nm and have a linear fiber form without branching. In addition, because it is the largest biological resource on earth, and is a sustainable resource that is produced in an amount of about 70 billion tons per year, it contributes significantly to the reduction of carbon dioxide that affects global warming. Both economically and economically.

<Porosity>
The cellulose nonwoven fabric preferably has a porosity of 20 vol% or less, more preferably 15 vol% or less, and particularly preferably 13 vol% or less.

  When the porosity of the cellulose fiber layer formed of the cellulose nonwoven fabric is large, the transparency is deteriorated, and bubbles are left when the laminate is formed. Therefore, scattering occurs at the interface and haze increases, which is not preferable. Moreover, when the porosity of a cellulose nonwoven fabric is high, when it is set as a laminated body, since the sufficient reinforcement effect by a fiber is not acquired and a linear expansion coefficient becomes large, it is unpreferable. Therefore, the porosity of the cellulose nonwoven fabric is preferably as small as possible.

The porosity here refers to the volume ratio of the voids in the cellulose nonwoven fabric. The porosity can be calculated from the area, thickness, and weight of the nonwoven fabric according to the following formula. In the following, the porosity is determined on the assumption that the density of cellulose is 1.5 g / cm ³ .
Porosity (vol%) = {1-B / (1.5 × A × t)} × 100
Here, A is the area (cm ² ) of the nonwoven fabric, t is the thickness (cm) of the nonwoven fabric, and B is the weight (g) of the nonwoven fabric.

In addition, the thickness of a cellulose nonwoven fabric is measured by 10 points | pieces about various positions of a nonwoven fabric using a film thickness meter (Mitutoyo Co., Ltd. IP65), and is calculated | required by the average value.
Moreover, when calculating | requiring the porosity of the cellulose nonwoven fabric in a composite_body | complex, ie, a cellulose fiber layer, a porosity can also be calculated | required by carrying out image analysis of spectral analysis and SEM observation of the cross section of a composite_body | complex.

<Chemical modification>
The cellulose fiber forming the cellulose fiber layer may be chemically modified. The chemical modification is a functional group introduced by reacting a hydroxyl group in cellulose with a chemical modifier.

(Type of functional group)
As functional groups to be introduced into cellulose by chemical modification, acetyl group, acryloyl group, methacryloyl group, propionyl group, propioroyl group, butyryl group, 2-butyryl group, pentanoyl group, hexanoyl group, heptanoyl group, octanoyl group, nonanoyl group, Decanoyl group, undecanoyl group, dodecanoyl group, myristoyl group, palmitoyl group, stearoyl group, pivaloyl group, benzoyl group, naphthoyl group, nicotinoyl group, isonicotinoyl group, furoyl group, acyl group such as cinnamoyl group, 2-methacryloyloxyethylisocyanoyl Isocyanate group such as a group, methyl group, ethyl group, propyl group, 2-propyl group, butyl group, 2-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, noni Group, decyl group, undecyl group, dodecyl group, myristyl group, palmityl group, an alkyl group such as a stearyl group, an oxirane group, an oxetane group, a thiirane group, or the like thietane group. Among these, an acyl group having 2 to 12 carbon atoms such as an acetyl group, an acryloyl group, a methacryloyl group, a benzoyl group and a naphthoyl group, and an alkyl group having 1 to 12 carbon atoms such as a methyl group, an ethyl group and a propyl group are preferable. .

(Modification method)
The modification method is not particularly limited, and there is a method of reacting cellulose with a chemical modifier as described below. Although there are no particular limitations on the reaction conditions, a solvent, a catalyst, or the like may be used, or heating, decompression, or the like may be performed as necessary.

  As a kind of chemical modifier, 1 type, or 2 or more types chosen from the group which consists of cyclic ethers, such as an acid, an acid anhydride, alcohol, a halogenating reagent, isocyanate, alkoxysilane, and an oxirane (epoxy), are mentioned.

  Examples of the acid include acetic acid, acrylic acid, methacrylic acid, propanoic acid, butanoic acid, 2-butanoic acid, and pentanoic acid.

  Examples of the acid anhydride include acetic anhydride, acrylic anhydride, methacrylic anhydride, propanoic anhydride, butanoic anhydride, 2-butanoic anhydride, and pentanoic anhydride.

  Examples of the alcohol include methanol, ethanol, propanol, and 2-propanol.

  Examples of the halogenating reagent include acetyl halide, acryloyl halide, methacryloyl halide, propanoyl halide, butanoyl halide, 2-butanoyl halide, pentanoyl halide, benzoyl halide, and naphthoyl halide.

  Examples of the isocyanate include methyl isocyanate, ethyl isocyanate, propyl isocyanate, and the like.

  Examples of the alkoxysilane include methoxysilane and ethoxysilane.

  Examples of cyclic ethers such as oxirane (epoxy) include ethyl oxirane and ethyl oxetane.

Among these, acetic anhydride, acrylic acid anhydride, methacrylic acid anhydride, benzoyl halide, and naphthoyl halide are particularly preferable.
These chemical modifiers may be used alone or in combination of two or more.

(Chemical modification rate)
The chemical modification rate of the cellulose fiber defined below is preferably 8 mol% or more, more preferably 15 mol% or more, based on the total hydroxyl groups of the cellulose fiber. The chemical modification rate is preferably 65 mol% or less, more preferably 50 mol% or less, based on the total hydroxyl groups of the cellulose fiber.

  If the chemical modification rate is too low, it may be colored when heated in the lamination process. On the other hand, if the chemical modification rate is too low, the hydrophilicity of the non-woven fabric increases and the water absorption increases, which is not preferable. On the other hand, if the chemical modification rate is too high, the cellulose structure is destroyed and the crystallinity is lowered, so that the resulting laminate has a large linear expansion coefficient, which is not preferable.

<Definition>
The chemical modification rate refers to the proportion of all hydroxyl groups in cellulose that have been chemically modified, and is measured by the following method.

これを解いていくと、以下の通りである。

<Measurement method>
The chemical modification rate can be determined by the following titration method.
0.05 g of cellulose nonwoven fabric is precisely weighed, and 6 mL of methanol and 2 mL of distilled water are added thereto. After stirring this at 60-70 ° C. for 30 minutes, 10 mL of 0.05N aqueous sodium hydroxide solution is added. The mixture is stirred at 60 to 70 ° C. for 15 minutes and further stirred at room temperature for one day. Titrate with 0.02N aqueous hydrochloric acid using phenolphthalein.
Here, from the amount Z (mL) of the 0.02N hydrochloric acid aqueous solution required for the titration, the number of moles Q of the substituent introduced by the chemical modification is obtained by the following formula.
Q (mol) = 0.05 (N) × 10 (mL) / 1000
−0.02 (N) × Z (mL) / 1000
The relationship between the number of moles Q of the substituent and the chemical modification rate X (mol%) is calculated by the following formula (cellulose = (C ₆ O ₅ H ₁₀ ) _n = (162.14) _n , repetition Number of hydroxyl groups per unit = 3, molecular weight of OH = 17). In the following, T is the molecular weight of the substituent.

Solving this, it is as follows.

<Method for producing cellulose nonwoven fabric>
Although the manufacturing method of a cellulose nonwoven fabric is not specifically limited, For example, it can manufacture as follows.

  In the production of the nonwoven fabric, the cellulose raw material is refined or refined as necessary, and then the cellulose dispersion (usually an aqueous dispersion of cellulose) is formed by filtration or coating to form a gel film. After film formation, it is dried to make a nonwoven fabric.

  The chemical modification may be performed after film formation on a nonwoven fabric, or may be performed on cellulose before film formation on the nonwoven fabric, but the former is preferable. After the chemical modification is completed, it is preferable to thoroughly wash with water and then dry.

  The method for producing such a nonwoven fabric will be described in more detail.

(Manufacture of non-woven fabric)
For the production of the nonwoven fabric, refined cellulose fibers are used.
When bacterial cellulose is used as a cellulose raw material, cellulose fibers can be obtained by culturing bacteria that produce cellulose. By removing this product from the medium and removing it by washing it with water or treating it with alkali, for example, water-containing bacterial cellulose containing no bacteria can be obtained. Since bacteria produce fine cellulose, they can be used as they are without being refined.

  Woods such as conifers and hardwoods, and cottons such as cotton linters and cotton lint are refined by bleaching with general chlorine, extraction with acids, alkalis, and various organic solvents, and then refined cellulose to obtain refined cellulose. obtain. Further, seaweeds such as valonia and squirrel and squirts of sea squirts are refined to obtain refined cellulose.

  As a disperser for refining cellulose, it is preferable to use a blender type disperser, a high-pressure homogenizer, an ultrahigh-pressure homogenizer, a counter impact disperser such as Massomizer X (manufactured by Masuko Sangyo Co., Ltd.), or the like. In particular, the ultra-high pressure homogenizer is effective for uniformly refining cellulose.

  It is preferable that the cellulose concentration of the cellulose dispersion at the time of refining is 0.05% by weight or more, preferably 0.1% by weight or more, and more preferably 0.3% by weight or more. If the cellulose concentration is too low, it takes too much time to filter and apply. The cellulose concentration is preferably 10% by weight or less, preferably 3% by weight or less, and more preferably 2% by weight or less. If the cellulose concentration is too high, the viscosity becomes too high or uniform fine cellulose cannot be obtained.

  When a nonwoven fabric is obtained by filtration, the concentration of the cellulose dispersion is preferably 0.01% by weight or more, preferably 0.05% by weight or more, and more preferably 0.1% by weight or more. If the concentration is too low, filtration takes an enormous amount of time, which is not preferable. The concentration of the cellulose dispersion is 1.5% by weight or less, preferably 1.2% by weight or less, more preferably 1.0% by weight or less. If the concentration is too high, a uniform nonwoven fabric cannot be obtained.

In addition, as a filter cloth at the time of filtration, it is important that fine cellulose does not pass through and the filtration rate is not too slow. Such a filter cloth is preferably a nonwoven fabric, a woven fabric, or a porous membrane made of an organic polymer. The organic polymer is preferably a non-cellulose organic polymer such as polyethylene terephthalate, polyethylene, polypropylene, polytetrafluoroethylene (PTFE) or the like.
Specifically, a porous film of polytetrafluoroethylene having a pore diameter of 0.1 to 5 μm, for example, 1 μm, polyethylene terephthalate or polyethylene fabric having a pore diameter of 0.1 to 5 μm, for example, 1 μm, and the like can be given.

(Chemical modification of nonwoven fabric)
As described above, the chemical modification of the non-woven fabric may be performed after the non-woven fabric is manufactured and after the non-woven fabric is dried, or may be performed without drying. Therefore, it is preferable. In the case of drying, it may be blown dry, dried under reduced pressure, or dried under pressure. Moreover, you may heat. The drying conditions in this case can employ the same conditions as the drying conditions described later.

  The chemical modification of the non-woven fabric can take a normal method. That is, chemical modification can be performed by reacting cellulose of the nonwoven fabric with a chemical modifier according to a conventional method. At this time, if necessary, a solvent or a catalyst may be used, or heating, decompression, or the like may be performed. As the catalyst, it is preferable to use a basic catalyst such as pyridine, triethylamine, sodium hydroxide or sodium acetate, or an acidic catalyst such as acetic acid, sulfuric acid or perchloric acid.

  As the temperature condition, if it is too high, there are concerns about yellowing of cellulose, a decrease in the degree of polymerization, and the like. The reaction time is several minutes to several tens of hours depending on the chemical modifier and the chemical modification rate.

  After performing chemical modification in this way, it is preferable to wash thoroughly with water in order to terminate the reaction. If the unreacted chemical modifier remains, it is not preferable because it causes coloring later or becomes a problem when laminated with the polycarbonate resin film.

(Dry)
In the production of the cellulose nonwoven fabric, the nonwoven fabric is finally dried. The drying may be air drying, drying under reduced pressure, or pressure drying. Moreover, you may heat. In the case of heating, the heating temperature is preferably 50 ° C to 250 ° C. If the heating temperature is too low, drying may be insufficient, and if the heating temperature is too high, the cellulose may be colored or decomposed. When pressurizing, 0.01-5 MPa is preferable. If the applied pressure is too low, the cellulose nonwoven fabric may be wrinkled. If the applied pressure is too high, the cellulose nonwoven fabric cannot be dried uniformly and may be crushed or decomposed.

{Laminate}
Next, the physical properties of the laminate of the present invention obtained by laminating and integrating the polycarbonate resin layer and the cellulose fiber layer of the present invention will be described.

<Thickness ratio>
When the thickness of the polycarbonate resin layer is smaller than the thickness of the cellulose fiber layer, the impact resistance of the laminate is insufficient. For this reason, in the polycarbonate resin / cellulose fiber laminate of the present invention, the thickness of the polycarbonate resin layer is 1.4 times or more, preferably 1.5 times or more, more preferably 1.7 times the thickness of the cellulose fiber layer. Double or more. The upper limit of the thickness ratio is not particularly limited, but there is a problem that the linear expansion coefficient increases if the polycarbonate resin layer is too thick. For this reason, the thickness of the polycarbonate resin layer is preferably 30 times or less, particularly 20 times or less, with respect to the thickness of the cellulose fiber layer.

  In addition, in this invention, the thickness of a cellulose fiber layer is the total thickness of the cellulose fiber layer which comprises a polycarbonate resin / cellulose fiber laminated body, and when it has several cellulose fiber layers in a laminated body, The thickness refers to the total thickness of the plurality of cellulose fiber layers. Similarly, the thickness of the polycarbonate resin layer is the total thickness of the polycarbonate resin layer constituting the polycarbonate resin / cellulose fiber laminate. When the laminate has a plurality of polycarbonate resin layers, the thickness of the polycarbonate resin layer is And the total thickness of the plurality of polycarbonate resin layers.

  The thickness per one layer of the cellulose fiber layer constituting the laminate of the present invention is substantially the same as the thickness per sheet of the cellulose nonwoven fabric used for the production of the laminate. Moreover, the thickness per layer of the polycarbonate resin layer which comprises the laminated body of this invention is substantially equivalent with respect to the thickness of the polycarbonate resin film used in order to form the said layer.

<Layer structure>
The layer structure of the laminate of the present invention is not particularly limited as long as it has a polycarbonate resin layer and a cellulose fiber layer, and preferably has a structure in which the cellulose fiber layer is sandwiched between polycarbonate resin layers. That is, a sandwich structure in which polycarbonate resin layers are laminated via a cellulose fiber layer is preferable from the viewpoint of improvement in water resistance, improvement in transparency, and improvement in mechanical properties.

  This laminated structure is not limited to the three-layer laminated structure of polycarbonate resin layer / cellulose fiber layer / polycarbonate resin layer, but polycarbonate resin layer / cellulose fiber layer / polycarbonate resin layer / cellulose fiber layer / polycarbonate resin layer, or further, polycarbonate resin layer. And a laminated structure in which cellulose fiber layers are alternately laminated and the outermost layer is a polycarbonate resin layer. The number of laminated layers is preferably 3 to 500 layers, particularly 3 to 50 layers in total of the polycarbonate resin layer and the cellulose fiber layer. Increasing the number of layers increases the strength. However, if the number is too large, the transparency is lowered and the practicality is lost. In any case, the outermost layer is preferably a polycarbonate resin layer in order to improve water resistance, transparency, and mechanical properties.

  In addition, although the laminated body of this invention may have layers other than a polycarbonate resin and a cellulose fiber layer, it is normally set as the laminated body of a polycarbonate resin layer and a cellulose fiber layer.

<Cellulose fiber layer ratio>
The content ratio of the cellulose fiber layer in the laminate of the present invention (cellulose fiber content ratio) is 10 wt% or more and 80 wt% or less, and the content ratio of the resin other than the cellulose fiber layer, that is, the polycarbonate resin is 20 wt%. The content is preferably 90% by weight or less. A more preferable range is a content ratio of the cellulose fiber layer of 15% by weight or more and 70% by weight or less, a content ratio of the resin other than cellulose is 30% by weight or more and 85% by weight or less, and a further preferable range is the content of the cellulose fiber layer. The ratio is 20% by weight or more and 60% by weight or less, and the content ratio of the resin other than cellulose is 40% by weight or more and 80% by weight or less. Here, the content ratio of the resin or cellulose fiber can be determined from the weight of the cellulose fiber layer before lamination and the weight of the laminate after lamination. Moreover, it can also obtain | require from the weight of the cellulose fiber which dipped the laminated body in the solvent in which resin is soluble, removed only resin, and remained. In addition, there are a method for obtaining from the specific gravity of the resin and a method for obtaining by quantitatively determining the functional groups of the resin and cellulose using NMR and IR.

<Thickness>
The thickness (total thickness) of the laminate of the present invention is preferably 20 μm or more and 10 cm or less. Strength can be maintained by using a laminate having such a thickness. The thickness of the laminate is more preferably 50 μm to 6 cm, and still more preferably 80 μm to 5 cm.

<Haze>
The laminate of the present invention can be made into a laminate having high transparency, that is, low haze, by using cellulose fibers having a fiber diameter smaller than the wavelength of visible light for the cellulose fiber layer.
In this case, the haze value (50 μm thickness haze) at a thickness of 50 μm of the laminate is preferably 20 or less, more preferably 10 or less, and preferably 1 or less when used as various transparent materials. .

  The haze of the laminate can be measured, for example, with a haze meter manufactured by Suga Test Instruments, and the value of C light is used.

<Total light transmittance>
The total light transmittance (50 μm thickness total light transmittance) at a thickness of 50 μm of the laminate of the present invention is preferably 60% or more, particularly 70% or more, particularly 80% or more, and particularly preferably 90% or more. If the total light transmittance of 50 μm thickness is less than 60%, the laminate may be translucent or opaque, making it difficult to use it in applications where transparency is required.

  The total light transmittance of the laminate can be measured, for example, using a Suga Test Instruments haze meter, and the value of C light is used.

<Linear expansion coefficient>
The laminate of the present invention is a laminate having a low linear expansion coefficient. The linear expansion coefficient of the laminate of the present invention is preferably 1 to 50 ppm / K, more preferably 40 ppm / K or less, and particularly preferably 35 ppm / K or less. When the linear expansion coefficient of the laminate exceeds 50 ppm / K, the object of the present invention of providing a composite having a low linear expansion coefficient cannot be achieved.
In addition, the linear expansion coefficient of a laminated body is measured by the method described in the term of the below-mentioned Example.

<Porosity>
Even if the gap of the cellulose fiber layer portion of the laminate of the present invention is a laminate, the gap of the cellulose nonwoven fabric used for forming the cellulose fiber layer is basically maintained. Therefore, the porosity of the cellulose fiber layer of the laminate of the present invention is more preferably 20 vol% or less, and further preferably 15 vol% or less. It is especially preferable that it is 13 vol% or less.
As described above, the porosity of the cellulose fiber layer in the laminate can be measured, for example, by spectroscopic analysis, image analysis of SEM observation or TEM observation of the cross section of the laminate, and is used for manufacturing the laminate used. It is equivalent to the porosity of the cellulose nonwoven fabric.

<Bending strength>
The bending strength of the laminate of the present invention is preferably 40 MPa or more, more preferably 100 MPa or more. When the bending strength is lower than 40 MPa, sufficient strength cannot be obtained, which may affect the use of a structural material or the like to which a force is applied.
In addition, the bending strength of a laminated body is measured according to the method described in the term of the below-mentioned Example based on JIS specification K7171.

<Bending elastic modulus>
The flexural modulus of the laminate of the present invention is preferably 0.2 to 100 GPa, more preferably 1 to 50 GPa. If the flexural modulus is lower than 0.2 GPa, sufficient strength cannot be obtained, which may affect the use in applications where force is applied such as structural materials.
In addition, the bending elastic modulus of a laminated body is measured according to the method described in the term of the below-mentioned Example based on JIS specification K7171.

<Fracture strain>
The bending fracture strain of the laminate of the present invention is preferably 0.5% or more, more preferably 1% or more. The higher the bending fracture strain, the better, but usually it is 20% or less.
In addition, the bending fracture strain of the laminate is measured according to the method described in the section of Examples described later in accordance with JIS standard K7171.

<Storage elastic modulus E '>
The storage elastic modulus E ′ of the laminate of the present invention is preferably 2.6 to 20 GPa, particularly 3.0 to 15 GPa. When the storage elastic modulus E ′ is lower than 2.6 GPa, the storage elastic modulus E ′ is the same as that of the polycarbonate resin layer alone, and a sufficient mechanical property cannot be obtained. The higher the storage elastic modulus E ′, the better, but the upper limit is usually 20 GPa or less, which is the storage elastic modulus E ′ of the cellulose nonwoven fabric.
In addition, the storage elastic modulus E ′ of the laminate is measured according to the method described in the section of Examples described later in accordance with JIS K7198.

[Manufacturing method of laminate]
The production method of the laminate of the present invention is not particularly limited, but preferably, the polycarbonate resin film and cellulose nonwoven fabric described above are used according to the production method of the present invention, and these are laminated in a predetermined laminated structure and heat-sealed. It is manufactured by doing.

In this heat fusion, pressurization may be performed, or heat fusion may be performed under reduced pressure conditions.
If the heating temperature at the time of heat fusion is too low, the adhesion between the polycarbonate resin layer and the cellulose fiber layer is insufficient, and if it is too high, the polycarbonate resin layer and the cellulose fiber layer may be thermally deteriorated. It is preferable to set it as ° C, especially 200-250 ° C.

  Further, if the pressure is too low, the adhesion between the polycarbonate resin layer and the cellulose fiber layer is insufficient, and if it is too high, the thickness of the laminate may be reduced. It is preferable to set it as 3 MPa.

  In addition, it is preferable that the atmosphere at the time of heat-sealing is set to a vacuum or a reduced pressure condition, so that an effect that a laminate without bubbles can be produced is produced. As decompression conditions in this case, the degree of vacuum is preferably 2 hPa or less.

  Specific methods of heat fusion include injection molding such as hot press molding and insert injection molding, and extrusion molding such as coextrusion and extrusion coating.

  As a more specific method of hot press molding, heat fusion between the polycarbonate resin film and the cellulose nonwoven fabric reached a vacuum degree of 1.7 hPa or less using a vacuum heater press machine (Mikado Technos Co., Ltd.) or the like. Thereafter, preheating is performed at 180 to 250 ° C. for about 1 to 30 minutes, and then pressurization is performed at 0.1 to 5 MPa for about 20 seconds to 5 minutes.

  Prior to heat fusion between the polycarbonate resin film and the cellulose nonwoven fabric, the surface of the cellulose nonwoven fabric may be primed. Examples of the primer treatment include a method of applying a primer treatment solution such as an acrylic primer to a laminated surface of a cellulose nonwoven fabric with a polycarbonate resin film, a method of immersing a cellulose nonwoven fabric in such a primer treatment solution and impregnating the solution. It is done.

  Furthermore, prior to heat-sealing the polycarbonate resin film and the cellulose nonwoven fabric, the cellulose fibers of the cellulose nonwoven fabric may be surface-treated. Examples of the surface treatment include the following.

[Usage]
The laminate of the present invention comprising a polycarbonate resin layer and a cellulose fiber layer is described later by making use of properties such as strength, low water absorption, low colorability, low linear expansion, high elasticity, and high strength. Although it is applicable to various uses, depending on the use, other members may be further laminated, other layers may be laminated, and various treatments may be performed. You may laminate | stack films | membranes, such as a fluorine film and a hard coat film, and an impact-resistant and light-resistant raw material as needed.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

[Evaluation methods]
The physical properties and the like of samples prepared in the following examples and comparative examples were measured by the following evaluation methods and measurement methods.

これを解いていくと、以下の通りである。

<Chemical modification rate of polycellulose nonwoven fabric>
The chemical modification rate was determined by the following method.
0.05 g of cellulose nonwoven fabric was precisely weighed, and 6 mL of methanol and 2 mL of distilled water were added thereto. After stirring this at 60-70 ° C. for 30 minutes, 10 mL of 0.05N aqueous sodium hydroxide solution was added. This was stirred at 60 to 70 ° C. for 15 minutes and further stirred at room temperature for one day. The solution was titrated with 0.02N hydrochloric acid aqueous solution using phenolphthalein.
Here, from the amount Z (ml) of the 0.02N hydrochloric acid aqueous solution required for the titration, the number of moles Q of the substituent introduced by chemical modification is obtained by the following formula.
Q (mol) = 0.05 (N) × 10 (ml) / 1000
−0.02 (N) × Z (ml) / 1000
The relationship between the number of moles Q of the substituent and the chemical modification rate X (mol%) is calculated by the following formula (cellulose = (C ₆ O ₅ H ₁₀ ) _n = (162.14) _n , repetition Number of hydroxyl groups per unit = 3, molecular weight of OH = 17). In the following, T is the molecular weight of the substituent.

Solving this, it is as follows.

<Thickness of cellulose nonwoven fabric>
The thickness of the cellulose nonwoven fabric was measured at 10 points for various positions of the nonwoven fabric using a film thickness meter (IP65 manufactured by Mitutoyo Co., Ltd.), and the average value was obtained.

<Porosity of cellulose nonwoven fabric>
The porosity of the cellulose nonwoven fabric was calculated from the area, thickness and weight of the nonwoven fabric according to the following formula. In the following, the porosity is determined on the assumption that the density of cellulose is 1.5 g / cm ³ .
Porosity (vol%) = {1-B / (1.5 × A × t)} × 100
Here, A is the area (cm ² ) of the nonwoven fabric, t is the thickness (cm) of the nonwoven fabric, and B is the weight (g) of the nonwoven fabric.

<Haze of laminate>
Based on JIS standard K7136, the haze value by C light was measured using the haze meter by Suga Test Instruments.

<Total light transmittance of laminate>
Based on JIS standard K7105, the total light transmittance by C light was measured using the haze meter by Suga Test Instruments.

<Linear expansion coefficient of laminate>
The laminate was cut into 3 mm width × 30 mm length with a laser cutter. This was pulled in a pull mode using a TMA120 manufactured by SII at a chucking distance of 20 mm, a load of 10 g and a nitrogen atmosphere at room temperature to 120 ° C. at a rate of 5 ° C./min, from 120 ° C. to 25 ° C. at a rate of 5 ° C./min, 25 The linear expansion coefficient was determined from the measured values from 60 ° C. to 100 ° C. during the second temperature increase when the temperature was increased from 5 ° C. to 120 ° C. at 5 ° C./min.

<Bending elastic modulus, bending strength, fracture strain of laminate>
The laminate was cut into 25 mm width × 40 mm length with a laser cutter. This was tested in accordance with JIS standard K7171 at a fulcrum distance of 20 mm and a test speed of 1 mm / min, and bending elastic modulus, bending strength, and fracture strain were determined from the measured values.

<Storage elastic modulus E 'of laminate>
The laminate was cut into 5 mm width × 40 mm length with a laser cutter. From a measured value around 23 ° C. when the temperature was raised from −10 ° C. to 50 ° C. in a nitrogen atmosphere in a tensile mode using a SII DMS6100 in a tensile mode of 20 mm between chucks, frequencies of 1 Hz and 10 Hz, and a tension amplitude of 10 Hz. The storage elastic modulus E ′ was determined.

<Thickness of laminate>
The total thickness of the laminate was measured at 10 points at various positions of the laminate using a film thickness meter (IP165 manufactured by Mitutoyo Co., Ltd.), and the average value was obtained. Moreover, the thickness ratio of each layer which comprises a laminated body calculated | required each thickness by the method similar to total thickness measurement before laminating | stacking, and calculated thickness ratio from it.

[Production Example 1: Preparation of cellulose nonwoven fabric precursor solution]
Rice pine wood flour (Miyashita Wood Co., Ltd.) was degreased with a 2% by weight aqueous solution of sodium carbonate at 80 ° C. for 6 hours. After washing with demineralized water, lignin was removed by dipping in 0.66 wt% sodium chlorite and 0.14 wt% acetic acid aqueous solution at 80 ° C. for 5 hours. After washing with desalted water and filtering, the recovered purified cellulose was washed with desalted water and then immersed in a 5 wt% aqueous potassium hydroxide solution for 16 hours to remove hemicellulose. After washing with desalted water, a 0.5% by weight aqueous suspension was obtained, and a fine dispersion treatment was performed with an ultra-high pressure homogenizer (Ultimizer; manufactured by Suginoma Machine Co., Ltd.) to obtain a cellulose dispersion. The treatment conditions were 10 times at a pressure of 245 MPa.

[Example 1]
The cellulose dispersion obtained in Production Example 1 was diluted with water to a concentration of 0.14% by weight, and 800 g was put into a 120 mm diameter filter using PTFE having a pore diameter of 1 μm. The cellulose nonwoven fabric was obtained by press drying at 120 ° C. and 1 MPa for 5 minutes. The average fiber diameter of the cellulose fibers constituting this cellulose nonwoven fabric was 10 nm.
This cellulose nonwoven fabric was impregnated with 200 mL of acetic anhydride and heated at 60 ° C. for 7 hours. Thereafter, it was thoroughly washed with distilled water and press dried at 120 ° C. and 1 MPa for 5 minutes to obtain an acetylated cellulose nonwoven fabric having a thickness of 83 μm. The chemical modification rate of this nonwoven fabric was 17 mol%. The porosity was 13 vol%.

This non-woven fabric is sandwiched between two polycarbonate resin films (Iupilon: Mitsubishi Engineering Plastics Co., Ltd., thickness 100 μm) and reaches a vacuum degree of 1.7 hPa using a vacuum heater press (Mikado Technos Co., Ltd.). After that, it was preheated at 210 ° C. for 10 minutes, and then pressed with 10 KN (pressurized surface: 150 × 150 mm) for 1 minute to produce a laminate.
The evaluation results of the obtained laminate are shown in Table 1. In addition, the cellulose fiber content rate of this laminated body was 31 weight%.

[Example 2]
An acetylated cellulose non-woven fabric produced by the same method as in Example 1 was impregnated with an acrylic primer solution and air-dried overnight, and then two polycarbonate resin films (Iupilon: Mitsubishi Engineering Plastics Co., Ltd.) as in Example 1. The laminate was manufactured by sandwiching the film between the company and a thickness of 100 μm) under the same conditions.
The evaluation results of the obtained laminate are shown in Table 1.

[Comparative Example 1]
The cellulose dispersion obtained in Production Example 1 was diluted with water to a concentration of 0.14% by weight, and 800 g was put into a 120 mm diameter filter using PTFE having a pore diameter of 1 μm, so that the solid content became about 5% by weight. When 2-propanol was added, it was replaced with water. Then, it press-dried at 120 degreeC and 2 Mpa for 5 minutes, and obtained the cellulose nonwoven fabric.
This cellulose nonwoven fabric was impregnated with 200 mL of acetic anhydride and heated at 60 ° C. for 7 hours. Thereafter, it was thoroughly washed with distilled water and press-dried at 120 ° C. and 1 MPa for 5 minutes to obtain an acetylated cellulose nonwoven fabric having a thickness of 54 μm. The chemical modification rate of this nonwoven fabric was 17 mol%. The porosity was 39 vol%.

  This non-woven cellulose surface is dissolved in a solution obtained by dissolving polycarbonate resin (Novalex 7020AD2: manufactured by Mitsubishi Engineering Plastics Co., Ltd.) in dichloromethane (special grade reagent, manufactured by Junsei Chemical Co., Ltd.) at a concentration of 10% by weight. Dipped 4 times perpendicular to The dip time was 5 seconds and the dip interval was 5 minutes. Then, after air-drying for 3 hours, after making it vacuum-dry at 160 degreeC overnight, after reaching | attaining vacuum degree 1.7hPa using a vacuum heater press machine (made by Mikado Technos Co., Ltd.) for 10 minutes at 210 degreeC. Preheating was performed, and then pressure was applied at 10 KN (pressure surface: 150 × 150 mm) for 1 minute to prepare a double-sided polycarbonate resin-coated cellulose nonwoven fabric.

In addition, this method is a method of impregnating the voids of the cellulose nonwoven fabric with the polycarbonate solution, and the productivity is poor.
Table 1 shows the evaluation results of the obtained polycarbonate resin-impregnated cellulose nonwoven fabric.

  This polycarbonate resin-impregnated cellulose nonwoven fabric has a total thickness of 100 μm, in which a cellulose nonwoven fabric having a thickness of 54 μm is impregnated with a polycarbonate resin.

[Example 3]
The cellulose dispersion obtained in Production Example 1 was diluted with water to a concentration of 0.13% by weight, charged in 4043 g into a 300 mm diameter filter using PTFE having a pore diameter of 1 μm, and press-dried at 120 ° C. and 1 MPa for 5 minutes. Thus, a cellulose nonwoven fabric was obtained.
This cellulose nonwoven fabric was impregnated with 3000 mL of acetic anhydride and heated at 60 ° C. for 7 hours. Thereafter, it was thoroughly washed with distilled water and press-dried at 120 ° C. and 1 MPa for 5 minutes to obtain an acetylated cellulose nonwoven fabric having a thickness of 65 μm. The chemical modification rate of this nonwoven fabric was 17 mol%. The porosity was 13 vol%.

This acetylated cellulose nonwoven fabric was cut into 5 sheets of 50 mm × 100 mm square, impregnated with an acrylic primer solution and allowed to air dry overnight, and then six polycarbonate resin films (Iupilon: Mitsubishi Engineering Plastics) (Alternatively, 100 μm in thickness), and laminated by heating and fusing under the same conditions as in Example 1.
Table 2 shows the evaluation results of the obtained laminate.

[Example 4]
A cellulose nonwoven fabric was obtained in the same manner as in Example 3 except that 4959 g of cellulose dispersion was added to a 300 mm diameter filter, and acetylated and heat-sealed with a polycarbonate resin film in the same manner to produce a laminate. The resulting acetylated cellulose nonwoven fabric had a thickness of 82 μm, a chemical modification rate of 17 mol%, and a porosity of 13 vol%.
Table 2 shows the evaluation results of the obtained laminate.

  From Tables 1 and 2, it can be seen that according to the present invention, a composite having high transparency, high elasticity, a low linear expansion coefficient, and a good balance of properties such as impact resistance can be provided with high productivity.

  The laminate of the present invention comprising a polycarbonate resin layer and a cellulose fiber layer has high transparency, can realize a laminate having high strength, low water absorption, low coloration, low linear expansion coefficient and low haze, and optical Because of its excellent characteristics, it is suitable as a display, substrate, or panel for liquid crystal displays, plasma displays, organic EL displays, field emission displays, rear projection televisions, and the like. Moreover, it is suitable for substrates for solar cells such as silicon-based solar cells and dye-sensitized solar cells. Moreover, it can be used suitably for window materials for automobiles, window materials for railway vehicles, window materials for houses, window materials for offices and factories, and the like.

  Furthermore, the laminate of the present invention can be used as a structural material other than the transparent material by utilizing characteristics such as a low linear expansion coefficient, high elasticity, and high strength. In particular, it is suitably used as automotive materials such as glazing, interior materials, outer plates and bumpers, personal computer casings, home appliance parts, packaging materials, building materials, civil engineering materials, marine products, and other industrial materials.

Claims (9)

  A laminate comprising a polycarbonate resin layer and a cellulose fiber layer, wherein the polycarbonate resin layer has a thickness of 1.4 times or more of the thickness of the cellulose fiber layer.   The polycarbonate resin / cellulose fiber laminate according to claim 1, wherein the cellulose fiber layer is sandwiched between polycarbonate resin layers.   The polycarbonate resin / cellulose fiber laminate according to claim 1 or 2, wherein an average fiber diameter of cellulose fibers constituting the cellulose fiber layer is 200 nm or less.   The polycarbonate resin / cellulose fiber laminate according to any one of claims 1 to 3, wherein the porosity of the cellulose fiber layer is 35 vol% or less.   The polycarbonate resin / cellulose fiber laminate according to any one of claims 1 to 4, wherein cellulose fibers constituting the cellulose fiber layer are chemically modified.   The method for producing a polycarbonate resin / cellulose fiber laminate according to any one of claims 1 to 5, further comprising a step of laminating the cellulose fiber layer and the polycarbonate resin layer and heat-sealing.   The method for producing a polycarbonate resin / cellulose fiber laminate according to claim 6, wherein after the primer treatment is performed on the laminated surface of the cellulose fiber layer, the cellulose fiber layer and the polycarbonate resin layer are laminated and heat-sealed.   The method for producing a polycarbonate resin / cellulose fiber laminate according to claim 6 or 7, wherein the cellulose fiber layer and the polycarbonate resin layer are laminated and heat-fused after chemically modifying the cellulose fiber.   The method for producing a polycarbonate resin / cellulose fiber laminate according to any one of claims 6 to 8, wherein the heat fusion is performed under reduced pressure.