JP5299818B2 - Offset printing paper and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide printing paper excellent in ink color developability, inking property, opacity, and whiteness and off-set printing suitability, despite being lightweight non-coated paper highly compounded with deinked pulp, and to provide a method for producing the printing paper. <P>SOLUTION: The offset printing paper is such as to meet the following requirements (1) to (10): (1) the whiteness is &ge;60%; (2) the opacity is &ge;85%; (3) the flatness is &ge;30 s and the smoothness difference between the obverse and reverse surfaces is &le;5 s; (4) the oil absorption is &ge;50 s and the oil absorption difference between the obverse and reverse surfaces is &le;10 s; (5) the basis weight is 35-50 g/m<SP>2</SP>; (6) the mechanical pulp accounts for 20-60 mass% of the total pulp; (7) the ash content is 5-10%; (8) white carbon is contained in terms of ash at 0.5-2.5%; (9) the oil absorption of the filler contained per cm<SP>3</SP>paper is 0.035-0.070 cc; and (10) a starch-based surface treatment agent is coated for one side in an amount of 0.2-1.0 g/m<SP>2</SP>. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

The present invention relates to an offset printing paper having a low basis weight, a high whiteness, and a good ink coloring property during printing, and a method for producing the same.

Paper is used in most cases, such as newspapers, books, magazines, posters, calendars, pamphlets, wrapping paper, etc., and the types and characteristics of printing paper vary depending on various printing methods and applications. For example, the offset printing method creates an oleophilic image area (the area to be printed) and a hydrophilic non-image area on the printing plate, and thinly applies water called fountain solution, then ink. When ink is applied, the ink adheres only to the image area where water is repelled, and this is transferred to the blanket and the ink is transferred from the blanket to the paper. Since dampening water is used, the surface strength of the paper is important so that it will not adhere to the blanket and be removed as paper dust when wet. In addition, the gravure printing method is a method in which ink is transferred to the paper in the depressions on the plate, so that the plate and the paper are in uniform contact with each other so that there is no minute dot on the surface (speckle). It is required to have no irregularities and high smoothness.

Printing paper used for flyers such as supermarkets and home centers is mainly fine-coated paper having a basis weight of 49.0 to 54.2 g / m ² . The finely coated paper is a coating liquid containing pigment and adhesive that improves ink fillability. The printability required for flyer applications with a small coating amount compared to ordinary coated paper. Is given. Printing paper used for this flyer is usually printed by a rotary offset printing press.
In recent years, there has been a noticeable trend toward lowering costs, and there is a move to downgrade paper. Specifically, the basis weight has been lowered, the quality paper has been changed to medium quality paper and lower grade paper, and the coated paper has been changed to non-coated paper. In flyer applications, there is a movement to change from finely coated paper to non-coated paper. Here, uncoated paper refers to printing paper that has not been coated with pigments. Advanced printing paper and intermediate printing in the “Category classification table for paper and board” in the Japan Paper Association “Paper and Paper Statistics” Paper and paper classified as lower grade printing paper.
However, since non-coated paper is inferior in ink colorability to fine-coated paper, it cannot be expected to have a beautiful print finish that attracts consumers and is required for leaflets. In particular, when non-coated paper is used for a multi-colored flyer, the ink coloring property is worse than when finely coated paper is used, and the difference in printed finish becomes remarkable. Therefore, improvement of ink color development in non-coated paper has been a problem.

One type of printing paper is called super calendered paper (commonly called SC paper: Super Calendered Paper). In Europe and the United States, it has recently been used for color printing by offset printing or gravure printing as magazines, promotional flyers, catalogs, etc. Has been. This super calendar paper is a non-coated paper that is located between the non-coated paper such as normal newsprint and printing paper and the fine coated paper. Paper with gloss and smoothness.

Super calender paper passes through the nip between many rolls under linear pressure in order to be lightweight and have high gloss, and it is inevitable that the paper will be crushed. High opacity and high stiffness (rigidity) Hard to get. Moreover, usually, the main raw material is mechanical pulp such as ground pulp or thermomechanical pulp that tends to increase in paper thickness, and it is difficult to blend old paper in high amounts.

There are the following applications as techniques for improving the whiteness, opacity, and printability of uncoated paper.
Uses light calcium carbonate and light calcium carbonate-silica composite. (Patent Document 1) Spindle-aggregated light calcium carbonate or needle-aggregated light calcium carbonate is blended as a filler and processed with a soft nip calender of 6 nips or more. (Patent Document 2) Water is applied to the surface of the metal roll treated surface before and / or during the treatment with a hot soft nip calender having two or more nips. (Patent Document 3) In addition, as a low-medium-price printing paper excellent in printability and bookbinding suitability, specify the friction coefficient, shrinkage, oil absorption amount of filler, absorption amount of internal filler contained in 1 g of paper, etc. There is what I did. (Patent Document 4)
However, none of the ink color development properties has been sufficiently studied.

Recently, so-called free papers and free magazines, the number of copies of free information magazines and various advertisements that specify the target readers based on advertising revenue according to gender and age group has increased. Although demands for gloss and printing effects are not as strong as paper, demand for paper that is lightweight and superior in print quality compared to conventional uncoated paper is expected to increase in the future.

JP 2008-248451 A JP 2008-274517 A JP 2008-274518 A Japanese Patent No. 4052083

An object of the present invention is to provide a non-coated paper containing a high amount of waste paper pulp, which is lightweight and has excellent ink colorability and offset printing suitability suitable for flyer applications, and a method for producing the same. It is to be.

As a result of examining the relationship between the ink color developability and the ink absorption ability of the filler appearing on the paper surface, the present inventors have found that the whiteness, opacity, smoothness, oil absorption, basis weight, and mechanical pulp content of the printing paper. It has been found that the above-mentioned problems can be solved by setting the rate, ash content, the type and content of filler used, the oil absorption amount, and the coating amount of the surface treatment agent within a certain range.

The invention according to claim 1 is a non-coated paper for offset printing that satisfies the following conditions (1) to (1 1 ).
(1) Whiteness 60% or more (2) Opacity 85% or more (3) Smoothness 30 seconds or more, smoothness front / back difference 5 seconds or less (4) Oil absorption 50 seconds or more, oil absorption front / back difference 10 seconds or less (5 ) Basis weight 35-50g / m ²
(6) 20 to 60% by mass of newspaper waste paper deinked pulp ( 7 ) 20 to 60% by mass of mechanical pulp in total pulp ( 8 ) Ash content of 5 to 10%
( 9 ) Contains 0.5 to 2.5% of white carbon as ash ( 10 ) Oil absorption amount of filler contained per ³ cm3 of paper is 0.035 to 0.070 cc
(11) The invention according to starch-based surface treatment agent to one surface 0.2 to 1.0 g / ^{m 2} coating according to claim 2, formulated 20-60% by weight of waste newspaper deinked pulp, all in-pulp mechanical pulp Is a method for producing an offset printing paper, in which paper slurry is made from a pulp slurry containing 20 to 60% by mass, containing 0.5 to 2.5% of white carbon as ash, and containing a filler excluding white carbon And producing an uncoated paper for offset printing, characterized in that the oil absorption of the filler contained per cm ^{3 of} paper is 5 to 10% ash and 0.035 to 0.070 cc. It is a method.

According to the offset printing paper and the method for producing the same of the present invention, it is possible to provide an offset printing paper having a low basis weight, a high whiteness, and a good ink coloring property during printing.

Embodiments of the present invention will be described below.
For the production of the printing paper of the present invention, a paper machine comprising each process of a wire part, a press part, a dryer part, and a reel part is used. The type of the paper machine is not particularly limited, and a long net paper machine, a twin wire paper machine, etc. can be used as appropriate, but an on-top type or a gap former type twin wire paper machine is desirable, especially a gap former type that dehydrates from both sides. A paper machine is preferred. By making paper with a gap former type paper machine, the filler is distributed on the surface layer of the paper, and the ink is held by the surface layer filler during printing and the penetration into the inside of the paper layer is suppressed, so that the ink coloring property is improved. In the case of a long net type paper machine, there is a difference in the front and back of pulp fibers and fillers, so that a difference in front and back in printability tends to occur.

In the printing paper according to the present invention, kraft pulp, waste paper pulp, mechanical pulp, and the like can be used as raw material pulp. As kraft pulp, softwood bleached kraft pulp (NBKP), hardwood bleached kraft pulp (LBKP) and the like can be used. In addition, as waste paper pulp, waste paper deinking pulp (DIP) such as newspaper waste paper deinking pulp and high-quality waste paper deinking pulp can be used. As the mechanical pulp, stone ground pulp (SGP), pressurized stone ground pulp (PGP), refiner ground pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), or the like can be used.

The printing paper concerning this invention contains 20-60 mass% of mechanical pulp in all the pulps. By setting it as the content rate of 20-60 mass%, bulkiness can be obtained, rigidity can be made high and high opacity can be obtained. It is preferable that the Canadian standard freeness (CSF) of the mechanical pulp to be blended is adjusted to 80 to 150 ml. When the freeness is lower than 80 ml, high rigidity cannot be obtained, and when the freeness is higher than 150 ml, the number of binding fibers increases and the ink deposition property is inferior.
Moreover, it is preferable that the printing paper concerning this invention contains the waste paper pulp, and the compounding ratio should have many, but when printability and rigidity are considered, it is preferable to set it as 20-60 mass%.
The content of mechanical pulp can be controlled within the range by adjusting the blend of mechanical pulp and the blend of DIP. Since DIP is manufactured from newspaper waste paper, magazine waste paper, high-quality waste paper, etc., chemical pulps such as NBKP and LBKP and the above-mentioned mechanical pulps are mixed. However, since the mass ratio of each pulp in DIP is almost constant, the mass ratio of mechanical pulp can be predicted and adjusted even if DIP is blended.

In the printing paper of the present invention, a filler is added for the purpose of improving the ink coloring property, the ink setting property, the opacity and the whiteness. In particular, white carbon having high oil absorption is added so as to contain 0.5 to 2.5% as ash. If the white carbon content is less than 0.5%, it is necessary to increase the content of the filler having a low oil absorption amount in order to set the oil absorption amount of the filler contained in the paper cm ³ described later to a specific range. In this case, it is easy to cause piling problems. Further, when the white carbon content is larger than 2.5%, white carbon having a small apparent specific gravity tends to weaken the bond between fibers, and in this case as well, it tends to cause a problem of piling.
The type of filler other than white carbon is not particularly limited, and fillers generally used for printing paper can be used. Specifically, inorganic fillers such as calcium carbonate, titanium dioxide, talc, clay and silica, plastic pigments, and the like can be used.
The ash content (JISP8251) of the printing paper of the present invention is preferably 5 to 10%. When the ash content is lower than 5%, opacity and whiteness are insufficient.

And by containing white carbon and other fillers, the oil absorption amount (according to JISK5101-13-2: 2004 boiled sea urchin oil method) possessed by the filler contained in the paper cm ³ is 0.035 to 0.070 cc. It is trying to become. By setting it as such a range, the ink which contacted with the filler is immediately absorbed by the filler which exists in the paper surface layer, and stays in the paper surface layer, Therefore The ink color development property becomes favorable. If the oil absorption amount of the filler contained per cm ^{3 of} paper is less than 0.035 cc, the ink is not sufficiently absorbed by the filler present on the paper surface layer and penetrates into the paper layer, resulting in poor ink color development. Even if the oil absorption amount of the filler contained per cm ^{3 of} paper is larger than 0.070 cc, the ink coloring property is not greatly improved, and there are the following problems.
That is, in order to increase the oil absorption amount of the filler contained in the paper cm ^3, it is necessary to increase the content of the filler having a small oil absorption amount or to use a filler having a large oil absorption amount. In the former case, the presence of the filler reduces the fiber-to-fiber bond, and tends to cause a problem of piling. In the latter case, a filler having a large oil absorption has a small apparent specific gravity and a strong tendency to weaken the bond between fibers, so that it is likely to cause a problem of a pile even at a relatively low content.

In the present invention, the reason for specifying the oil absorption amount of the filler contained per cm ^{3 of} paper is that this value is an index of the ink absorption ability by the filler appearing on the paper surface layer, and is per unit volume of paper. This is because the ink absorption ability can be expressed without depending on the basis weight. Although it may be per unit area, in this case, conversion by basis weight is required.
In the case of coated paper, the quality of ink color development depends on the ink absorption capacity of the coated layer, but in the case of non-coated paper, it is considered to depend on the ink absorption capacity of the filler that appears on the paper surface. It is done.

In the present invention, a sulfate band, a sizing agent, a bulk improver, a paper strength enhancer and the like can be added to the raw material pulp. As the sizing agent, a sizing agent such as rosin sizing agent, alkyl ketene dimer, alkenyl succinic anhydride can be used. As the paper strength enhancer, cationic starch, polyacrylamide resin and the like can be used. In addition, additives such as a wet paper strength enhancer, a slime control agent, a pitch control agent, an antifoaming agent, and a dye can be used as necessary.

In the present invention, a surface treatment agent containing no pigment is applied.
The surface treatment agent is preferably coated with a starch-based surface treatment agent at 0.2 to 1.0 g / m ² on one side for the purpose of improving the surface strength. If the coating amount of the starch-based surface treatment agent is less than 0.2 g / m ² on one side, the surface strength is insufficient and piling occurs. Even if it exceeds 1.0 g / m ² , the effect of improving the surface strength is not greatly changed, which is uneconomical. The coating amount of the surface treatment agent is preferably the same on the front and back.
The oil absorption (former JISP3001) is preferably 50 seconds or more, and the difference between the front and back of the oil absorption is preferably 10 seconds or less. If the oil absorption is less than 50 seconds, the ink absorption speed is fast, so that the ink penetrates into the paper layer, and the breakthrough becomes noticeable.
If the difference in front and back of the oil absorption exceeds 10 seconds, the ink colorability on the front and back sides may be different, which may give an unnatural appearance.
The oil absorption can be adjusted by the oil absorption amount and addition rate of the filler to be used, the coating amount of the surface treatment agent, the calendar treatment conditions, and the like.

As a coating apparatus for coating the surface treatment agent, a roll coater such as a 2-roll size press coater or a gate roll coater can be used. As the surface treatment agent to be applied, cationized starch, oxidized starch, polyacrylamide, polyvinyl alcohol, carboxymethyl cellulose, styrene maleic acid copolymer, styrene acrylic acid copolymer and the like can be used.

In producing the printing paper of the present invention, the paper is dried by a dryer and then smoothed by a calendar device. As such a calendar device, a commonly used calendar device such as a chilled calendar, a soft calendar, or a gloss calendar can be used. Depending on the required smoothness, the number of nips, nip pressure, roll temperature, roll material, roll hardness, etc. are set. In order to obtain ink fillability, the smoothness (JISP8119) is 30 seconds or more, the smoothness The difference between the front and back is preferably 5 seconds or less.

The printing paper of the present invention has a basis weight (JISP 8124) of 35 to 50 g / m ² . If the basis weight is less than 35 g / m ² , the rigidity is insufficient. Larger basis weight is more advantageous for rigidity, but 50 g / m ² or less is preferable from the viewpoint of resource saving. The printing paper thus obtained has a whiteness (JISP8148) of 60% or more and an opacity (JISP8149) of 85% or more.

Hereinafter, the effects of the present invention will be specifically described by Examples and Comparative Examples. In addition, unless otherwise indicated,% represents the mass%, and the addition amount represents the solid content or the active ingredient with respect to the absolutely dry pulp.

Example 1
White carbon (oil absorbing oil) is used as a filler in a pulp dispersion composed of 25 parts by mass of LBKP (350 ml CSF), 35 parts by mass of thermomechanical pulp (110 ml CSF), and 40 parts by mass of newspaper waste ink deinked pulp (230 ml CSF, 45% by mass of mechanical pulp content). Amount 200cc / 100g) is added to 2.2% by mass and light calcium carbonate (oil absorption 85cc / 100g) is added to 5.0% by mass, and a yield improver (trade name: ND260, manufactured by Hymo Co., Ltd.) is added to the pulp. Paper was made by adding 200 ppm. Use a gate roll coater with the same coating amount on the front and back so that the coated amount of oxidized starch (trade name: Oji Ace A, manufactured by Oji Cornstarch Co., Ltd.) is 0.50 g / m ² per side as a surface treatment agent in the dryer part Application and drying were performed to obtain an offset printing paper having a basis weight of 49.0 g / m ² and a moisture content of 6.0%. Tables 1 and 2 show the evaluation results of the obtained printing paper.
In addition, the oil absorption amount (cc) of the filler contained per cm ^{3 of} paper is obtained by the following equation.
Paper density [g / cm ³ ] × ((100−moisture [%]) / 100) × (ash content [%] / 100) × filler oil absorption [cc / 100 g] / 100

(Example 2)
An offset printing paper was obtained in the same manner as in Example 1 except that 1.5% by mass of white carbon and 5.0% by mass of light calcium carbonate were added as fillers and paper was made. Tables 1 and 2 show the evaluation results of the obtained printing paper.

(Example 3)
An offset printing paper was obtained in the same manner as in Example 1 except that 1.0% by mass of white carbon and 7.0% by mass of light calcium carbonate were added as fillers to make paper. Tables 1 and 2 show the evaluation results of the obtained printing paper.

Example 4
Addition of 1.0% by weight of white carbon as filler and 5.0% by weight of light calcium carbonate to make paper, and the coating amount of oxidized starch as a surface treatment agent in the dryer part is 0.25 g / side. An offset printing paper was obtained in the same manner as in Example 1 except that m ² was set. Tables 1 and 2 show the evaluation results of the obtained printing paper.

(Example 5)
Addition of 1.0% by weight white carbon as filler and 7.0% by weight light calcium carbonate to make paper, and the coating amount of oxidized starch as a surface treatment agent in the dryer part is 0.75 g / side. An offset printing paper was obtained in the same manner as in Example 1 except that m ² was set. Tables 1 and 2 show the evaluation results of the obtained printing paper.

(Example 6)
An offset printing paper was obtained in the same manner as in Example 1 except that the basis weight was 43.0 g / m ² . Tables 1 and 2 show the evaluation results of the obtained printing paper.

(Example 7)
An offset printing paper was obtained in the same manner as in Example 2 except that the basis weight was 43.0 g / m ² . Tables 1 and 2 show the evaluation results of the obtained printing paper.

(Example 8)
An offset printing paper was obtained in the same manner as in Example 3 except that the basis weight was 43.0 g / m ² . Tables 1 and 2 show the evaluation results of the obtained printing paper.

Example 9
An offset printing paper was obtained in the same manner as in Example 4 except that the basis weight was 43.0 g / m ² . Tables 1 and 2 show the evaluation results of the obtained printing paper.

(Example 10)
The basis weight was 37.0 g / m ² , white carbon was added as a filler, 2.5% by mass, light calcium carbonate was added so as to contain 5.0% by mass, paper was made, and oxidized starch as a surface treatment agent in the dryer part. An offset printing paper was obtained in the same manner as in Example 1 except that the coating amount was 1.0 g / m ² per side. Tables 1 and 2 show the evaluation results of the obtained printing paper.

(Comparative Example 1)
An offset printing paper was obtained in the same manner as in Example 1 except that 0.5% by mass of white carbon and 5.0% by mass of light calcium carbonate were added as fillers and paper was made. Tables 1 and 2 show the evaluation results of the obtained printing paper.

(Comparative Example 2)
An offset printing paper was obtained in the same manner as in Example 1 except that 1.0% by mass of white carbon and 12.0% by mass of light calcium carbonate were added as fillers and paper was made. Tables 1 and 2 show the evaluation results of the obtained printing paper.

(Comparative Example 3)
An offset printing paper was obtained in the same manner as in Example 1 except that white carbon was added as a filler in an amount of 2.7% by mass and light calcium carbonate was added in an amount of 5.0% by mass. Tables 1 and 2 show the evaluation results of the obtained printing paper.

(Comparative Example 4)
An offset printing paper was obtained in the same manner as in Comparative Example 1 except that the basis weight was 43.0 g / m ² . Tables 1 and 2 show the evaluation results of the obtained printing paper.

(Comparative Example 5)
An offset printing paper was obtained in the same manner as in Comparative Example 2 except that the basis weight was 43.0 g / m ² . Tables 1 and 2 show the evaluation results of the obtained printing paper.

(Comparative Example 6)
An offset printing paper was obtained in the same manner as in Comparative Example 3 except that the basis weight was 43.0 g / m ² . Tables 1 and 2 show the evaluation results of the obtained printing paper.

The test method and evaluation method are as follows.
(Basis weight) JISP8124: 1998 Paper and board - basis weight measurement method (thickness) JISP8118: 1998 Paper and board - Test method (oil absorption) of thickness and density oil absorption with the filler contained per paper cm ³ ( cc / cm ³ ) was calculated for each filler by the following formula and totaled. The oil absorption amount of the filler is based on JISK5101-13-2: 2004 boiled sea urchin oil method.
Paper density [g / cm ³ ] × ((100−moisture [%]) / 100) × (ash content [%] / 100) × filler oil absorption [cc / 100 g] / 100
(Ash) JISP8251: 2003 paper, paperboard and pulp-Ash content test method-525 ° C combustion method (whiteness) JISP8148: 2001 paper, paperboard and pulp-ISO whiteness (diffuse blue light reflectance) measurement method (opacity) JISP8149: 2000 paper and paperboard-Opacity test method (backing of paper)-Diffuse irradiation method (smoothness) JISP8119: 1998 Paper and paperboard-Smoothness test method (oil absorption) by Beck smoothness tester Old JISP3001: 1995 Measured according to newspaper rolls.
(Evaluation of Ink Coloring and Piling) Using an offset rotary printing press, four-color printing was performed at a printing speed of 700 rpm and a paper surface temperature of 120 ° C. (process ink for off-wheel ink, red, indigo and yellow), and 5,000 copies were printed.
The ink coloring property was evaluated in three stages: excellent, good, and poor.
Piling was evaluated in the following four stages by observing the blanket and the printed surface.
A: The blanket was good with no occurrence of piling.
○: Piling occurred slightly in the blanket, but there was no problem on the printed surface.
Δ: Piling occurred on the blanket, and scum was observed on the printed surface.
X: Piling occurred on the blanket and the printed surface was severely damaged.

As shown in Tables 1 and 2, in Examples 1 to 10 of the present invention, it can be seen that both ink color development evaluation and piling evaluation are good.
In Comparative Example 1, the oil absorption per cm ^{3 of} paper is as low as 0.031 cc / cm ^3, and the ink color development evaluation is poor.
In Comparative Example 2, since the oil absorption per cm ^{3 of} paper is as high as 0.074 cc / cm ³ and the ash content is as high as 14.8%, the ink coloring property evaluation is good, but the piling evaluation is poor.
In Comparative Example 3, the white carbon content is as high as 2.7%, and the piling evaluation is poor.
In Comparative Example 4, the oil absorption per cm ^{3 of} paper is as low as 0.033 cc / cm ^3, and the ink coloring property evaluation is poor.
In Comparative Example 5, since the oil absorption per cm ^{3 of} paper is as high as 0.076 cc / cm ³ and the ash content is as high as 14.8%, the ink coloring property evaluation is good, but the piling evaluation is poor.
In Comparative Example 6, the white carbon content is as high as 2.7%, and the piling evaluation is poor.

The offset printing paper of the present invention is suitably used for flyer applications, and can also be used as free paper or free magazine paper .

Claims (2)

Non-coated paper for offset printing that satisfies the following conditions (1) to (1 1 ).
(1) Whiteness 60% or more (2) Opacity 85% or more (3) Smoothness 30 seconds or more, smoothness front / back difference 5 seconds or less (4) Oil absorption 50 seconds or more, oil absorption front / back difference 10 seconds or less (5 ) Basis weight 35-50g / m ²
(6) 20 to 60% by mass of newspaper waste paper deinked pulp ( 7 ) 20 to 60% by mass of mechanical pulp in total pulp ( 8 ) Ash content of 5 to 10%
( 9 ) Contains 0.5 to 2.5% of white carbon as ash ( 10 ) Oil absorption amount of filler contained per ³ cm3 of paper is 0.035 to 0.070 cc
(11) one surface of the starch-based surface treatment agent 0.2 to 1.0 g / ^{m 2} coating A method for producing offset printing paper, in which 20-60 mass% of waste newspaper deinked pulp is blended and pulp slurry containing 20-60 mass% of mechanical pulp in the total pulp is used as a raw material, with white carbon as ash Including 0.5 to 2.5% and a filler excluding white carbon, the oil absorption amount of the filler contained per 5 cm of ash and ³ cm of paper is 0.035 to 0.070 cc. A method for producing non-coated paper for offset printing, characterized in that the adjustment is performed as follows.