JP2010203002A - Base paper for process release paper, and process release paper using the base paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base paper for a process release paper to be used in producing a carbon fiber-reinforced resin material and excellent in dimensional stability to heat, and to provide a process release paper using the above base paper. <P>SOLUTION: The base paper for a process release paper is such that: at least one side of a substrate based on wood pulp is provided with one or more coating layers composed of an inorganic pigment and a binder. In the base paper, the fiber alignment ratio determined based on an ultrasonic wave transmission speedometer for the substrate is 1.20 or less, and the coating layer contains kaolin and a styrene-butadiene copolymer as major components. In the base paper, after heating the base paper at 150°C for 2 min, the lateral extension after 24 h at 23°C and RH 50% is 0.5% or less. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a base paper for process release paper excellent in dimensional stability by heat and a process release paper using the base paper for process release paper, and to a process release paper used for manufacturing a carbon fiber reinforced resin material. It is preferably used.

The base paper for release paper is widely used as a backing paper for adhesive paper or adhesive tape by applying a release agent such as silicone on the surface thereof. Since silicone is expensive, the base paper for release paper has high sealing performance against organic solvents (silicone sealing effect) so that as little silicone as possible can be applied to the base paper to effectively release it. ) Is required.
In addition, the process release paper used in the process of manufacturing sheet-like molded products such as synthetic resins and ceramics, holds a fluid raw material as a support, peels it from the product after various treatments, and removes it. It is what is done. Therefore, the support of the process release paper is required to have dimensional stability with respect to various processing steps in addition to the release performance. In particular, when undergoing a heat treatment step, if a dimensional change or curl occurs due to heat, a defect occurs in the molded product. Among the dimensional changes, particularly shrinkage becomes a problem in terms of quality including wrinkled surface defects. In addition, the curl causes not only quality problems such as product deformation but also deterioration of operability such as deterioration of peeling workability.

Conventionally, as a support for such process release paper, those based on polyethylene laminate paper, those based on glassine paper, and the like have been used. However, in the case of polyethylene laminated paper, there are many problems in heat resistance, and in the case of glassine paper, dimensional changes due to moisture absorption, curling, and surface smoothness reduction have been problems.

As the process paper having excellent dimensional stability due to heat, NBKP was contained in the pulp, and the paper surface of the base paper was adjusted to a pH of 5 or more and less than 8 at a freeness of 400 to 500 ml, and held at 200 ° C. for 2 minutes. There has been proposed a process paper having a shrinkage rate of 1.0% or less in the horizontal direction and 0.5% or less in the vertical direction (Patent Document 1).
Further, a base paper for release paper having a coating layer containing polyvinyl alcohol on one side or both sides of the base paper is described (Patent Documents 2 and 3), and the base paper is coated or impregnated with water-resistant polyvinyl alcohol. A base paper for process release paper has been proposed (Patent Document 4). Further, a base paper for release paper is proposed in which a coating layer having an inorganic pigment / styrene / butadiene copolymer weight mixing ratio of 7/3 to 3/7 is provided on at least one side of the base paper in an amount of 7 to 30 g / m ² per side. (Patent Document 5), however, the dimensional stability against heat of 120 ° C. or higher was insufficient.

JP 2008-248410 A JP 2005-314859 A Japanese Patent No. 3135651 JP 2007-9348 A Japanese Patent No. 3385219

The object of the present invention is to manufacture a reinforced resin material such as carbon fiber. In the process where the process release paper is cooled to room temperature or lower after heating at 120 to 150 ° C., product quality defects (carbon aligned in the vertical direction) The object is to provide a process release paper base paper having excellent dimensional stability against heat and a process release paper using the process release paper base paper.
The dimensional stability against heat is, in detail, how to suppress the behavior of the base paper to expand and contract due to moisture absorption and desorption by heating and cooling. In the dimensional stability of the present invention, the most important thing is to suppress the lateral elongation.

As a result of intensive studies to solve the above-mentioned problems, the present inventors set the fiber orientation ratio of the base paper mainly composed of wood pulp to 1.20 or less, and kaolin and styrene-butadiene copolymer on at least one side of the base paper. By providing a coating layer mainly composed of coalescence (hereinafter abbreviated as SBR), smoothness and silicone sealing effect are imparted, and there is no decrease in strength due to heat, and dimensional stability is improved. I found.
By using the above-mentioned means, the process release paper base paper was heated at 150 ° C. for 2 minutes, and the lateral elongation after 24 hours at 23 ° C. and 50% relative humidity was controlled to 0.5% or less. The process release paper which solved the said subject came to be able to be provided.

The present invention includes the following inventions.
(1) A base paper for process release paper, comprising at least one coating layer mainly composed of an inorganic pigment and a binder on at least one side of a base paper mainly composed of wood pulp, the ultrasonic wave of the base paper The fiber orientation ratio measured based on the propagation velocity measuring instrument is 1.20 or less, the coating layer is mainly composed of kaolin and styrene-butadiene copolymer, and the base paper for the process release paper is 150 ° C. A base paper for process release paper having a transverse elongation of 0.5% or less after 24 hours under the conditions of 2 minutes heating at 23 ° C. and 50% relative humidity.

(2) The base paper for process release paper as described in (1) which contains a bulking agent in the said base paper.

(3) The base paper for process release paper as described in (2) whose said bulking agent is a fatty acid polyamide-type compound and / or a hydrated silicate.

(4) The process according to any one of (1) to (3), wherein a mixing ratio of the inorganic pigment containing kaolin and SBR of the coating layer is 8/2 or more and substantially does not contain polyvinyl alcohol. Base paper for release paper.

(5) The base paper for process release paper of any one of (1)-(4) in which the said base paper contains glass fiber.

(6) Process release paper which provided the release agent layer on the coating layer of the base paper for process release paper of any one of (1)-(5).

The present invention relates to a process release paper base paper excellent in dimensional stability against heat and a process release paper using the process release paper base paper, and to a process release paper used for manufacturing a carbon fiber reinforced resin material. It is preferably used.

  In the present invention, the fiber orientation ratio measured based on the ultrasonic propagation velocity measuring instrument of the base paper needs to be 1.20 or less. Incidentally, when the fiber orientation ratio exceeds 1.20, it is insufficient to make the orientation of the fibers constituting the base paper random, and the elongation in the lateral direction becomes large.

  Here, the fiber orientation of the base paper refers to the tendency that the pulp fibers flow out onto the wire of the paper machine and are aligned in the outflow (longitudinal) direction in the process of dewatering and forming a paper layer. In other words, since the paper stock flows and dehydrates on the wire at high speed during paper making, there are many fibers oriented in the machine direction (the flow direction of the raw material on the paper machine), and the tensile strength and stiffness in the machine direction are transverse. It is considerably stronger or higher than (width direction). Presumably, such vertical and horizontal differences (non-uniformity) of the base paper increase the elongation in the horizontal direction and deteriorate the dimensional stability due to heat.

In general, examples of methods for measuring fiber orientation of paper and the like include thermal expansion method, mechanical breaking strength method, X-ray diffraction method, ultrasonic method, microwave method, NMR method, polarized fluorescence method, dielectric measurement method and the like. It is done. In the present invention, an ultrasonic method is employed, and for example, the ultrasonic propagation velocity (V _md ) in the vertical direction and the ultrasonic propagation velocity (V _cd ) in the lateral direction are measured using “SONIC SHEEET TESTER” manufactured by Nomura Corporation. The ratio (V _md / V _cd ) was used as an index for evaluating the randomness of fiber orientation using the fiber orientation ratio. When the fiber orientation ratio is 1.0, the fibers are completely random, but in the case of actual machine paper, it has some fiber orientation and cannot be made 1.0 or less.

On the other hand, since the fiber orientation ratio is determined by the papermaking conditions in the machine, it is necessary to make the operation on the machine appropriate. Possible means include optimization of machine speed, ratio of fiber suspension jet inflow speed to wire speed (J / W ratio), wire shake, homing board and weir board arrangement, dandy roll, and the like. In particular, when making paper while sliding the wire horizontally and perpendicularly to the flow direction using a wire shaking device that can freely change the frequency and amplitude in the wire part, the direction of the pulp fibers is randomly oriented. Therefore, it is preferable. Further, in the operation of the paper machine, the speed of the rear part is generally faster, and paper is made while pulling the paper toward the reel. When this speed difference is increased, the pulp fibers are oriented in the flow direction, so the ratio V _r / V _w of the reel rotation speed (V _r ) to the wire rotation speed (V _w ) is 1.02-1. It is preferably 07. It is possible to make the fiber orientation ratio 1.20 or less by combining one or more of these means, but it is necessary to achieve harmony with other properties such as paper texture Needless to say.

(Basic paper manufacturing method)
The base paper used in the present invention can be produced by controlling the fiber orientation ratio and making paper by the method described in detail below.

  The pulp is beaten by a beater such as a beater, Jordan, a deluxe refiner, or a double disc refiner (hereinafter referred to as DDR). The degree of beating is preferably about 350 to 550 ml in terms of Canadian Standard Freeness (hereinafter referred to as CSF). When the beating degree is coarser than 550 ml CSF, the formation of the base paper is deteriorated and the peel surface quality is adversely affected. When refining finer than 350 ml CSF, dimensional stability deteriorates, which is not preferable.

As such pulp, hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), mechanical pulp (MP), and deinked waste paper pulp can be appropriately blended and used. Examples of mechanical pulp include unexposed and semi-exposed such as Stone Grand Pulp (GP), Pressurized Stone Grand Pulp (PGW), Refiner Grand Pulp (RGP), Chemi Grand Pulp (CGP), and Thermomechanical Pulp (TMP). Or bleached pulp can be used.
In the pulp blending of the base paper, it is preferable to blend a large amount of LBKP (hardwood bleached kraft pulp) excellent in dimensional stability, and it is preferable to blend 70 to 100% by mass of 100% by mass of the total pulp.

As for the basic weight of the base paper in this invention, 50-90 g / m < ² > is preferable. When the basis weight is lower than 50 g / m ² , the tensile strength and the Gurley stiffness are lowered, which is not preferable. On the other hand, if the basis weight is higher than 90 g / m ² , the mass of the release paper discarded after use is not preferable.

In the present invention, various internal additives can be used as necessary. For example, sizing agents such as rosin, styrene-maleic acid, alkyl ketene dimer, alkenyl ketene dimer, alkenyl succinic anhydride, internal sizing agents for natural and synthetic papermaking, various paper strength enhancers, filter Water-proofing agents such as aqueous improvers, yield improvers, polyamide polyamine epichlorohydrin resins, antifoaming agents, fixing agents, fluorescent whitening agents, colored dyes, and the like can be used.
Furthermore, starch, oxidized starch, cationized starch, carboxymethylated starch, carboxymethylcellulose, polyvinyl alcohol, anionic, cationic or amphoteric polyacrylamide resins are used in the stock as an internal paper strength enhancer. be able to.

It is preferable to add a bulking agent to the base paper used for the process release paper of the present invention in order to create voids between pulp fibers and inhibit the transmission of fiber shrinkage. Examples of such bulking agents include organic bulking agents and inorganic bulking agents.

Organic bulking agents include polyhydric alcohol and fatty acid ester compounds, nonionic surfactants, oil-based nonionic surfactants, sugar alcohol-based nonionic surfactants, sugar-based nonionic surfactants, polyhydric alcohol types Nonionic surfactant, higher alcohol, fatty acid bisamide compound, condensate of fatty acid and polyvalent amine, polyoxyalkylene adduct of higher alcohol or higher fatty acid, polyoxyalkylene adduct of higher fatty acid ester, polyhydric alcohol and fatty acid These include polyoxyalkylene adducts of ester compounds, fatty acid polyamide compounds, fatty acid polyamide amine compounds, alkylene oxide oligomers, and the like, but fatty acid polyamide compounds are preferred from the viewpoint of heat-resistant dimensional stability.

Although the optimal addition amount of an organic type bulking agent changes with kinds of bulking agent, it is preferable to add 0.1-0.5 mass% with respect to a pulp. When the addition amount is less than 0.1% by mass, the effect of improving the dimensional stability cannot be obtained, and when it is more than 0.5% by mass, the strength is greatly lowered, which is not preferable.

  Examples of inorganic bulking agents include hydrated silicates and aluminosilicates, but hydrated silicates are preferred from the viewpoint of heat-resistant dimensional stability. In addition, it is preferable to use an organic bulking agent and an inorganic bulking agent in combination because the heat-resistant dimensional stability is further improved.

Hydrated silicate is a compound represented by the general formula xM ₂ O · ySiO ₂ , xMO · ySiO ₂ , xM ₂ O ₃ · ySiO ₂ , where M is Al, Fe, Ca, Mg, Na, K , Ti, or Zn (x and y are arbitrary positive numerical values).
Hydrated silicate is a bulky pigment with voids inside the particles compared to calcium carbonate, kaolin, and talc, which are commonly used for fillers, and is thought to penetrate between pulp fibers and inhibit fiber expansion and contraction. .

The hydrated silicate used in the present invention has a specific surface area of 15 to 160 m ² / g, an integrated capacity of pores having a pore diameter of 10 ⁵ mm or less, less than 4 cc / g, and a pore diameter of 0.10 to 0. .80 μm is preferable. When the specific surface area is less than 15 m ² / g, the particle size distribution becomes poor, the fine particles and coarse particles increase, and the internal bond strength decreases. If it exceeds 160 m ² / g, the bonding strength of the aggregated structure becomes weak, and it is not preferable because it tends to be crushed at the time of pulp slurry preparation and at the press pressure and calendar processing pressure, and the bonding area between fibers tends to increase.

When the cumulative capacity of pores with a pore diameter of 10 ⁵ mm or less is 4 cc / g or more, the cohesive strength of the agglomerated structure becomes weak, and it is easy to crush at the time of pulp slurry preparation and at the press pressure and calendar treatment pressure. This is not preferable because the bonding area tends to increase.
Moreover, if the pore diameter is less than 0.10 μm, the binding force of the aggregated structure is weakened, and is easily crushed at the time of pulp slurry preparation and at the press pressure and the calendering pressure, and the bonding area between fibers increases. When it exceeds 0.80 μm, the particle size distribution is deteriorated, fine particles and coarse particles are increased, and the internal bond strength is lowered.

Here, the specific surface area is the surface area of all the pores, assuming that the pore shape is a geometric cylinder, using a pore sizer 9320 (manufactured by Shimadzu Corporation), and is pressed into pressure within the measurement range. It is the value obtained from the relationship of the amount of mercury. The pore diameter is also a median pore diameter obtained from an integral specific surface area curve using a pore sizer 9320 (manufactured by Shimadzu Corporation). Furthermore, the cumulative volume of the pores is also a value when the pore sizer 9320 (manufactured by Shimadzu Corporation) is measured by a mercury intrusion method and integrated with a pore diameter of 10 ⁵ mm or less.

The hydrated silicate used in the present invention preferably has an average particle size of 10 to 40 μm. When the average particle size is less than 10 μm, the effect of improving the dimensional stability is poor, and when the average particle size exceeds 40 μm, coarse particles existing in the vicinity of the paper surface greatly reduce the smoothness of the paper, and after coating This is also undesirable because it affects the smoothness of the film.
In addition, the average particle diameter in the present invention is a value that is measured by a laser diffraction method using SALD2000J (manufactured by Shimadzu Corporation) and is 50% in volume integration. As the particle size distribution of the hydrated silicate, the standard deviation (σ) is preferably 0.350 or less. With such a particle size distribution, both coarse particles and fine particles are reduced, and when blended in paper, better surface strength and internal bond strength can be obtained.
The amount of hydrated silicate added is preferably 1 to 8% by mass in terms of ash in the paper. When the addition amount is less than 1% by mass, the effect of improving the dimensional stability cannot be obtained, and when it is more than 8% by mass, the strength is greatly lowered, which is not preferable.

In the present invention, it is preferable that the base paper further contains glass fiber in order to improve the heat-resistant dimensional stability. Glass fibers include cut fiber types cut to several millimeters in length, and milled fiber types in which the length is micro-ordered by grinding glass. It has the effect of inhibiting the transmission of stretching.
The glass fiber is not particularly limited, but a cut fiber having a diameter of 2 to 20 μm and a length of 1 to 3 mm is preferably used. Moreover, it is preferable that the addition amount of glass fiber is 8-15 mass% with respect to a pulp. When the addition amount is less than 8% by mass, the effect of improving the dimensional stability is small, and when it is more than 15% by mass, the effect of improving the dimensional stability is saturated, which is disadvantageous in terms of cost.

The base paper used for the process release paper of the present invention includes, in addition to the above bulking agent, heavy calcium carbonate, light calcium carbonate, calcium carbonate such as chalk, kaolin, calcined kaolin, pyrophyllite, sericite, Silicates such as talc, inorganic fillers such as titanium oxide, and organic fillers such as urea resin may be included. It is preferable to add the filler so that the total paper ash content of the filler is 2 to 20% by mass from the balance between strength and dimensional stability.

The paper made as described above can be subjected to a size press treatment, and as the chemicals used in the size press treatment, various conventionally used starches, polyvinyl alcohol, polyacrylamide resins and the like can be used. . In addition, although there is no restriction | limiting in particular about the adhesion amount in the case of performing a size press process, Generally 0.1 to 10 g / m < ² > is preferable at the dry adhesion amount of both surfaces total.

(About coating layer)
In the coating layer, kaolin as the main component contains 60% by mass or more of the total inorganic pigment. In addition to kaolin, inorganic pigments used in the coating layer include heavy calcium carbonate, light calcium carbonate, calcium carbonate such as chalk, calcined kaolin, phyllophyllite, sericite, talc and other silicates, titanium oxide However, kaolin and calcium carbonate are preferably used from the viewpoint of smoothness and silicone sealing effect.

In the binder used in the present invention, SBR contains 80% by mass or more of the total binder amount. SBR is excellent in film formability and advantageous in terms of cost. Besides SBR, conjugated diene copolymer latex such as methyl methacrylate-butadiene copolymer, polymer or copolymer of acrylic acid ester and methacrylic acid ester, polymer or copolymer of acrylic acid and methacrylic acid, etc. Acrylic copolymer emulsion, vinyl copolymer emulsion such as ethylene-vinyl acetate copolymer, and the like may be mixed as appropriate.

Moreover, a water-soluble resin can also be mixed and used as needed. For example, when the coating layer of the present invention is applied with a blade coater, it is preferable to add an appropriate amount of starch, cellulose derivative or the like in order to obtain optimum coating properties. In addition, examples of water-soluble resins include polyvinyl alcohol (hereinafter referred to as PVA), other modified PVA, modified starch such as polyvinyl pyrrolidone, oxidized starch, casein, and gelatin. PVA tends to deteriorate dimensional stability. Therefore, it is preferable not to add them. The reason why PVA deteriorates the dimensional stability is not clear, but PVA has a high film forming property, so it is presumed that the whole film is likely to shrink due to heat.

The coating layer is formed by using various coating apparatuses such as a blade coater, a bar coater, an air knife coater, a roll coater, a gravure coater, a slot die coater, and a curtain coater, at least on the base paper in an on-machine method or an off-machine method. One side is coated with a single layer or multiple layers. The coating apparatus is not particularly limited, but a blade coater is preferable because it is excellent in the smoothness of the coating layer and the silicone sealing effect.
The coating amount of the coating layer is not particularly limited, but a sufficient silicone sealing effect is exhibited if it is 10 to ²⁰ g / m ² per side. More preferably, it is 12-16 g / m < ² >.

The mixing ratio (solid content) of the inorganic pigment and SBR in the coating layer is preferably 8/2 or more. The mixing ratio of the inorganic pigment and SBR of 8/2 or more means that the blending amount of the inorganic pigment is 80% by mass or more of the total amount of the inorganic pigment and SBR. In order to improve the sealing effect of silicone, it is better that the mixing ratio of the inorganic pigment and SBR is low. However, in order to sufficiently exhibit the effects of the present invention, the coating layer is preferably formed by a blade coater. In this case, it is not preferable that the mixing ratio of the inorganic pigment and SBR is lower than 8/2 because the backing roll is easily soiled by the paint and the operation becomes difficult.
After forming the coating layer, it may be finished by passing it through a calendar to further improve the smoothness, but the dimensional stability is increased because the inter-fiber bonding area of the base paper tends to increase due to the calendar treatment. In order to increase, it is preferable not to perform the calendering after coating.

The base paper for process release paper needs to suppress the lateral elongation rate of the base paper for process release paper in the heating and cooling process. In order to eliminate the quality defect of the reinforced resin material, The lateral elongation after 24 hours under the condition of 50 ° C. and 50% relative humidity must be 0.5% or less. More preferably, it is 0.4% or less.
If the elongation percentage in the horizontal direction of the base paper for process release paper exceeds 0.5%, a gap occurs in the carbon fibers arranged in the vertical direction, resulting in a quality defect.

The process release paper of this invention provides the release agent layer on the coating layer of the above-mentioned process release paper base paper. The release agent layer is formed by applying a release agent layer coating solution on the coating layer of the base paper for process release paper and curing it. As the release agent, for example, a silicone resin, a fluorine resin, a long chain alkyl resin, or the like is used, and a silicone resin is preferably used in terms of release performance. Examples of the silicone resin include an addition reaction type, a condensation reaction type, an ultraviolet curable type, and an electron beam curable type. These include a solvent type silicone resin diluted in an organic solvent such as toluene and hexane, and an effective solid content of 100. Examples thereof include a solvent-free silicone resin of mass% and an emulsion type silicone resin in which a silicone resin is dispersed in water. Among these, addition reaction type, condensation reaction type, and ultraviolet curable solvent type silicone resins that are easy to design for quality such as adjustment of peeling force are preferably used.

  The addition reaction type silicone resin is preferably a resin obtained by heat-curing polydimethylsiloxane having a terminal vinyl group and / or hexenyl group and hydrogensiloxane using a platinum catalyst. Specific examples of the addition reaction type silicone resin preferably used include KS-776A, KS-839L, KS-847T, KS-779H, KS-837, KS-778, KS-830, and KS-3502 manufactured by Shin-Etsu Chemical Co., Ltd. , KS-774, KS-3703, KS-835, KS-847, KM-3951, KM-768, KNS-3501, KNS-303, KNS-320A, KNS-316, KNS-3300, KNS-3300, etc. SRX357, BY23-749, SD7333, BY24-179, SRX211, BY23-746, SRX345, BY24-4103, SD7320, SD7236, BY24-400, BY24-312, SD7226, LTC300B, LTC303E, LTC31 manufactured by Toray Dow Corning , LTC314, LTC350G, LTC450A, LTC371G, LTC750A, LTC760A, SP7015, SP7259, SP7020, SP7025, SP7248S, SP7268S, SP7030, SP7265S, LTC1005L, LTC1056L, TP XS56-B8656, XS56-C3223, XS56-A8012, XS56-C1467, TPR6700, XS56-A3749, TPR6710, TPR6712, XS56-A5730, XSR7029 (A), TPR6600, SL6625 and the like.

  Examples of the condensation reaction type silicone resin include those obtained by heat-curing polydimethylsiloxane having a hydroxyl group at the terminal and hydrogensiloxane using an organic tin catalyst. Specific examples of the condensation reaction type silicone resin preferably used include KS-723A / B, X-52-170, X-52-179 manufactured by Shin-Etsu Chemical Co., Ltd., SRX290, SRX244, SYL-OFF23 manufactured by Toray Dow Corning. SYL-OFF22A, YSR3022 by Momentive Performance Materials, XS56-A3075, and the like.

  Examples of the ultraviolet curable silicone resin include those in which vinyl siloxane undergoes a hydrosilylation reaction in the presence of a platinum catalyst. Specific examples of the silicone resin include X-62-5039, X-62-5040, X-62-7622, X-62-7502, KNS-5300, and KS-5508 manufactured by Shin-Etsu Chemical Co., Ltd. Examples of the ultraviolet curable silicone resin include those obtained by radical polymerization of a siloxane containing an alkenyl group and a siloxane containing a mercapto group using a photopolymerization catalyst. Specific examples include BY24-510 manufactured by Toray Dow Corning, BY24-510H, BY24-544, BY24-545, LTC851, BY24-561, BY24-562, and the like can be given. Furthermore, what carried out the photo-ring-opening polymerization of the epoxy group with the onium salt initiator is mentioned, and specific examples include TPR6500, TPR6501, TPR6502, UV9300, UV9315, UV9430, XS56-A2775, XS56 manufactured by Momentive Performance Materials. -A2982 etc. are mentioned.

The method for applying the release agent is not particularly limited, and a bar coater, an air knife coater, an offset gravure coater, a direct gravure coater, a micro gravure coater, a reverse gravure coater, a multistage roll coater, or the like is used. The coating amount of the release agent is 0.2 to ² g / m2.

The effect of dimensional stability in the present invention is largely determined by the base paper. In order to increase the dimensional stability of the base paper, it is effective to weaken the bond between the fibers of the base paper in addition to lowering the fiber orientation ratio as described above. If the bond between fibers is weakened, the internal bond strength, tensile strength, and elastic modulus of the base paper will decrease, so considering these strengths, the bulking agent, bulk filler, glass fiber, filler of the bulk paper added internally The blending amount and the linear pressure of the calendar may be determined appropriately.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to these Examples. Moreover, unless otherwise indicated, the part and% in an example show a mass part and mass%, respectively.

Example 1
(Manufacture of base paper)
Canada Standard Freeness (CSF) 450 ml softwood bleached chemical pulp (NBKP) slurry and 400 ml hardwood bleached chemical pulp (LBKP) slurry were mixed at 20/80 (solid content ratio), then 100 parts of absolutely dry pulp In addition, light calcium carbonate is added so as to be 4 parts, and further added so that 1.0 part of starch, 0.5 part of sulfuric acid band, and 0.02 part of yield improver (DR-1500, manufactured by Hymo Co., Ltd.) A paper stock was prepared. The paper stock is made by using a long paper machine to make a paper with a target basis weight of 80 g / m ² when air-dried and with a wire shaking device while sliding the wire so that the amplitude is 20 mm and the vibration frequency is 200 rpm. After dehydration, the sheet was dried by using a cylinder dryer. Thereafter, calendar treatment was performed at a linear pressure of 10 kg / cm to obtain a base paper.
(Formation of coating layer)
A pigment composed of 70 parts of fine kaolin (trade name: “Miragros OP”, average particle size: 0.25 μm, manufactured by Engelhard) and 20 parts of heavy calcium carbonate (trade name: “FMT90”, manufactured by Phimatech) Dispersed in water with a Coreless disperser to obtain a pigment slurry. To this slurry, 10 parts of SBR (trade name: “PA-9000”, manufactured by Nippon A & L Co., Ltd.) (solid content), 3.5 parts of pre-gelatinized oxidized starch (trade name: “ACE A”, manufactured by Oji Cornstarch Co., Ltd.) (Solid content), an antifoaming agent was added, and finally a coating solution having a solid content concentration of 64% was prepared. This coating solution was coated on both sides with a blade coater so that the dry coating amount per side was 15 g / m ² on the base paper produced as described above, and dried to produce base paper 1 for process release paper.

Example 2
In the production of the base paper of Example 1, 0.2 part of fatty acid polyamide compound (trade name: “Size Pine DL-FA20”, manufactured by Arakawa Chemical Co., Ltd.) as an organic bulking agent was added per 100 parts of absolutely dry pulp. Except for the above, a process release paper base paper 2 was prepared in the same manner as in Example 1.

Example 3
In the production of the base paper of Example 1, the same process as in Example 1 except that the hydrated silicate synthesized as described below was added to 4 parts per 100 parts of absolutely dry pulp. A base paper 3 was prepared.
(Synthesis of hydrated silicate)
357 parts of water, 427 parts of a 5% strength aqueous sodium sulfate solution and 347 parts of No. 3 sodium silicate as defined in JIS K 1408-1966 were sequentially added with stirring. The temperature was adjusted to 50 ° C. while stirring, and then the peripheral speed of the stirring blade was adjusted to 10 m / second, and 91 parts of sulfuric acid (concentration 20%) was added over 15 minutes to neutralize the first stage, and then The temperature was raised to 90 ° C. at a peripheral speed. Then, 20% sulfuric acid was added at this temperature while stirring until pH 5.5, and neutralization was performed in the second stage. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain a 12% hydrated silicate slurry.
The obtained hydrated silicate was measured with a laser diffraction particle size distribution meter (trade name: “SALD2000J”, manufactured by Shimadzu Corporation), and the particle diameter of the 50% volume integrated value was 15.5 μm. It was.

Example 4
In the production of the base paper of Example 1, the base paper for process release paper was the same as Example 1 except that 10 parts of cut fiber (diameter 5 μm, length 3 mm) was added as glass fiber per 100 parts of absolutely dry pulp. 4 was produced.

Example 5
In the production of the base paper of Example 1, a base paper 5 for process release paper was produced in the same manner as in Example 1 except that the pulp slurry used was only LBKP.

Example 6
A base paper 6 for process release paper was produced in the same manner as in Example 1 except that 100 parts of fine kaolin in the coating layer was used and no heavy calcium carbonate was added.

Example 7
On one side of the base paper 2 for process release paper prepared in Example 2, a coating liquid consisting of 10 parts of a heavy release silicone resin (trade name: KS-830, manufactured by Shin-Etsu Chemical Co., Ltd.) and 100 parts of toluene was completely dried. It was applied with a gravure coater so that the solid content was 1.0 g / m ² , dried and cured at 150 ° C.
Next, on the other side, a coating liquid consisting of 10 parts of a light release silicone resin (trade name: KS-847T, manufactured by Shin-Etsu Chemical Co., Ltd.) and 100 parts of toluene was prepared. It apply | coated so that it might become 0 g / m < ² >, it was made to dry and harden | cure, and the process release paper 1 of this invention was produced.

Example 8
A base paper 8 for process release paper was prepared in the same manner as in Example 1 except that 60 parts of fine kaolin, 20 parts of heavy calcium carbonate, and 20 parts of SBR were used in the coating layer.

Example 9
In the production of the base paper of Example 2, a base paper for process release paper was prepared in the same manner as in Example 2 except that a polyhydric alcohol type nonionic surfactant was added as an organic bulking agent instead of the fatty acid polyamide compound. 9 was produced.

Example 10
In the production of the base paper of Example 2, the hydrated silicate used in Example 3 was further added to 4 parts per 100 parts of absolutely dry pulp, and an organic bulking agent and an inorganic bulking agent were used in combination. Except for this, a base paper 10 for process release paper was produced in the same manner as in Example 2.

Comparative Example 1
A base paper for process release paper was produced in the same manner as in Example 1 except that the wire shaking device was stopped in Example 1 and the fiber orientation ratio of the base paper was set to 1.45.

Comparative Example 2
In Example 1, the wire-shaking device is stopped to set the fiber orientation ratio of the base paper to 1.45, the coating layer is increased to 50 parts fine kaolin, 20 parts heavy calcium carbonate, and 30 parts SBR. However, the coating was easy to adhere to the roll and continuous operation was difficult.

Comparative Example 3
In Example 1, except that the wire shaking device was vibrated to have an amplitude of 3 mm and a frequency of 50 rpm, the fiber orientation ratio of the base paper was 1.25, and the coating layer was changed as follows: Produced a base paper for process release paper in the same manner as in Example 1.
(Formation of coating layer)
A pigment composed of 70 parts of fine kaolin (trade name: “Miragros OP”, average particle size: 0.25 μm, manufactured by Engelhard) and 20 parts of heavy calcium carbonate (trade name: “FMT90”, manufactured by Phimatech) Dispersed in water with a Coreless disperser to obtain a pigment slurry. PVA (trade name: “PVA105”, manufactured by Kuraray Co., Ltd.) 10 parts (solid content), pre-gelatinized oxidized starch (trade name: “ACE A”, manufactured by Oji Cornstarch Co., Ltd.) 3.5 parts (solid content) ), An antifoaming agent was added, and finally a coating solution having a solid content of 25% was prepared. This coating solution was coated on both sides with a blade coater and dried so that the dry coating amount per side of the prepared base paper was 15 g / m ² .

The dimensional stability with respect to heat of the base paper for process release paper or the process release paper of Examples 1 to 10 and Comparative Examples 1 to 3 obtained as described above was evaluated by the following measurement method.
(Measurement method of dimensional stability)
A measurement sample conditioned at 23 ° C. and a relative humidity of 50% is cut to a length of 210 mm and a width of 15 mm so that the lateral direction of the base paper becomes the length direction. This is put in a 150 ° C. drier as it is, taken out immediately after being heated for 2 minutes, and read on the glass scale to the order of 0.01 mm. The length at this time is L ₀ .
Heated samples, 23 ° C., after 24 hours moisture under 50% relative humidity environment, reads the length of glass scale again, the length at this time is L _1. Elongation rate = (L ₁ −L ₀ ) / L ₀ was calculated and shown in Table 1. If this elongation is small, it is evaluated that the dimensional stability against heat is excellent.

In Examples 1 to 10, the fiber orientation ratio of the base paper is 1.20 or less, and the base paper for process release paper or the process release paper provided with a coating layer mainly composed of kaolin / SBR is 150 ° C. After heating for 2 minutes, the transverse elongation after 24 hours under the conditions of 23 ° C. and 50% relative humidity was 0.5% or less. Moreover, the elongation rate could be further suppressed by internally adding a bulking agent fatty acid polyamide compound, hydrated silicate, and glass fiber to the base paper.
In Comparative Examples 1 to 3, when the fiber orientation ratio of the base paper was higher than 1.20, the elongation was larger than 0.5%, and the dimensional stability was further deteriorated when the binder of the coating layer was PVA. Further, when the mixing ratio of the inorganic pigment and SBR in the coating layer was 8/2 or less, the coating was liable to adhere to the backing roll during blade coating, and continuous operation was difficult.

The process release paper base paper of the present invention and the process release paper using the process release paper base paper are excellent in dimensional stability against heat, and are preferably used for process paper used in the production of carbon fiber reinforced resin materials. Is.

Claims (6)

In a base paper for process release paper in which one or more coating layers mainly composed of an inorganic pigment and a binder are provided on at least one side of a base paper mainly composed of wood pulp, an ultrasonic propagation velocity measuring instrument for the base paper The fiber orientation ratio measured on the basis of 1.20 or less, the coating layer is mainly composed of kaolin and styrene-butadiene copolymer, and the process release paper base paper is heated at 150 ° C. for 2 minutes. A base paper for process release paper, wherein the elongation in the transverse direction after 24 hours under conditions of 23 ° C. and 50% relative humidity is 0.5% or less.   The base paper for process release paper according to claim 1, wherein the base paper contains a bulking agent. The base paper for process release paper according to claim 2, wherein the bulking agent is a fatty acid polyamide compound and / or a hydrated silicate. The mixing ratio of the inorganic pigment containing kaolin and the styrene-butadiene copolymer in the coating layer is 8/2 or more and substantially does not contain polyvinyl alcohol. The base paper for process release paper as described in the item. The base paper for process release paper according to any one of claims 1 to 4, wherein the base paper contains glass fibers. Process release paper which provided the release agent layer on the coating layer of the base paper for process release paper of any one of Claims 1-5.