JPS6235849A - Ink jet recording method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an inkjet (liquid jet) that performs recording by forming droplets of recording liquid (ink) and adhering them to a recording material such as paper. Regarding the recording method, in detail, we will discuss an inkjet recording method in which the volume of ejected droplets is temperature-compensated.

[Conventional technology]

The inkjet (liquid jet) recording method, which performs recording by forming droplets of recording liquid (ink) and adhering them to a recording material such as paper, produces extremely low noise that can be ignored during recording. This recording method has many advantages, such as being capable of high-speed recording and not requiring special processing called fixing.

A recording device used in this inkjet recording method converts an applied electric signal (ejection signal) into the energy necessary to eject the recording liquid from an orifice using an ejection energy generating element, and converts the applied electric signal Accordingly, it is common to have an inkjet recording head that includes a droplet forming means for ejecting recording liquid from an orifice to form droplets of the recording liquid.

On the other hand, when recording with an inkjet recording apparatus, a water-based recording liquid is usually used from the viewpoint of recording properties, safety, and the like. This aqueous recording liquid is generally formed from a recording agent component such as a pigment or dye, and water for dissolving or dispersing the recording agent component, or a solvent component whose main components are water and a water-soluble organic solvent.

[Problems to be Solved by the Invention] However, when recording is performed using a recording liquid having such a composition and an inkjet recording apparatus as described above, the recording apparatus W is operated under the same driving conditions. However, depending on the temperature conditions during recording, there may be differences in the recorded image density, and good image reproducibility may not be obtained, or the amount of recording liquid attached to the recording material may be too large. Inconveniences have been recognized, such as bleeding in the image and poor ejection of the recording liquid such as the recording liquid not being ejected, resulting in a decline in the functionality of the recording device that is affected by the temperature of the installation environment.

This is because the physical properties of the recording liquid change greatly depending on temperature, and the recording head itself has recording characteristics that depend on the temperature of the installation environment.As a result, even if the same driving voltage is applied to the recording head, This is because the characteristics of the ejected recording liquid deviate from the speed at which a good droplet ejection condition can be obtained, depending on various temperature conditions that are affected by the installation environment temperature of the printing device in the print head. It is.

In particular, according to a program corresponding to the image to be recorded, the voltage of the ejection signal applied to the print head is changed to control the size of the ejected droplets to be ejected, recording is performed while changing the dot diameter, and the recorded image is In the inkjet recording method for recording high-quality images by expressing midtones in gradations consisting of subtle changes in shading, the dot diameter is as specified by a predetermined program.
For example, an essential condition for good image formation is that it can always be obtained within a wide temperature range from low to high temperatures in the environment in which the recording head is installed. Therefore, the influence of temperature on ejected droplet formation as described above, in which a predetermined dot diameter cannot be obtained for a predetermined ejection signal voltage depending on the temperature conditions inside the recording head, significantly reduces image reproducibility. This was a major problem that needed to be resolved.

As a means for solving such problems, it is known that the recording apparatus is provided with a temperature compensation means for eliminating the influence 11F on the function of the recording apparatus due to temperature.

This temperature compensation means typically detects the temperature inside the recording head with a temperature detector, and operates a heating means such as a heater according to the output from the detector, so that the recording liquid can be discharged with good physical properties. One method is to sequentially adjust the temperature inside the recording head so that it is maintained within the range required to obtain the desired condition, and the other is to detect the temperature of the recording liquid inside the recording head with a temperature detector, and to adjust the temperature to the output from the detector. There is a method of adjusting the voltage of the ejection signal applied to the recording head as appropriate.

However, the method of temperature compensation using heating means,
In particular, it is necessary to further install a part that constitutes a heating means such as a heater in the recording device, resulting in an increase in the size of the recording device, an increase in power supply capacity, and an accompanying increase in the cost of the device or during use. There are problems with the recording characteristics of the device, such as generation of gas dissolved in the recording liquid when the temperature of the recording liquid rises due to rapid heating, causing printing defects.

On the other hand, the method of adjusting the voltage of the ejection signal applied to the recording head makes it possible to save power, reduce costs, and downsize the device compared to the method using the heating means described above.
It has various advantages such as high reliability, and its practical application is attracting attention. However, depending on the type of recording liquid used, the installed temperature compensation means may not function well, which is a problem that needs to be solved.

In view of these problems, the inventors of the present invention conducted extensive research and found that a recording liquid having the property that its viscosity can be maintained within a predetermined range within the temperature range within the temperature-compensated inkjet recording head. The present invention has been completed based on the discovery that by using the above, the temperature compensation means based on the method of adjusting the voltage of the ejection signal described above can be made to function well.

The purpose of the present invention is to make the temperature compensation system function well,
An object of the present invention is to provide an inkjet recording method that performs temperature compensation by adjusting the voltage of an ejection signal, which allows recording to be performed with good reproducibility without being affected by the temperature environment.

Another object of the present invention is to make it possible to apply a temperature compensation means based on a method of adjusting the voltage of an ejection signal to an inkjet recording method for recording high-quality images, thereby reducing power consumption and reducing power consumption.
It is an object of the present invention to provide a method for recording high-quality images with good reproducibility using a low-cost, miniaturized inkjet recording table W1.

[Means to solve problems]

The above objects can be achieved by the following invention.

That is, the present invention detects the temperature within a droplet forming means for forming ejected droplets of recording liquid according to an applied electric signal, and detects the temperature within a droplet forming means for forming ejected droplets of recording liquid by a temperature detecting means, and By adjusting the electric signal applied to the forming means by the ejection signal adjusting means, the volume of the ejected droplet is temperature-compensated and recording is performed, and the inside of the droplet forming means is temperature-compensated during recording. This is an inkjet recording method characterized by using a recording liquid having a viscosity of 3 to 30 cp at a temperature range of .

The method of the present invention can be suitably applied to recording using an inkjet recording apparatus 118 that uses a temperature compensation system based on the following principle.

That is, in an on-demand inkjet recording device, the relationship between drive voltage and ejected droplet volume can be expressed as in the following equation (2).

Z=to -V+b ・・・・・・・・・■2: Discharged liquid volume V: Driving voltage, b: Constant Here, b is a constant, and b has temperature dependence. The reference temperature in the relationship between drive voltage (V) and ejected droplet volume (Z) is set to T.

(''K), and the temperature inside the print head at the time of printing plan is T, l (TI#T・), then the relationship between the drive voltage (V) and the ejected droplet volume (Z) at each temperature is as follows. become that way.

ZT, = kt, ・Vt, + by, ””・-
■Zr, = kt, ・VT, +bT, +++++＊+m ■Here, the ejected droplet volume is temperature compensated so that the ejected droplet volume is the same as at T. even at temperatures other than To (TI). Therefore, from the relationship between the following formulas 〇 and ◯, we can obtain the relationship between vT and Vr as shown in the following formula ◯.

Vt, −(kt, /kt,) ・Vt, + (by
, /kr, ) - (by, /kt, )...■ On the other hand, the main factor for the temperature dependence of the relationship between the drive voltage and the ejected droplet volume is the temperature effect of the viscosity of the recording liquid. , which is known to be the -dimensional number of el/Tdk2. Here, k r, /k T,, b in formula ■
y, /kr, can be respectively expressed as follows.

k・/kt, = e (gin・) “9・) (L+, L2, M+, M2, are constants unrelated to temperature) Therefore, by rewriting the formula ■ as the following formula ■, -(b
t,/kt,) = ■ Here, by, /kt, is a constant that can be obtained experimentally.

In this way, the driving voltage (Vt,) that is actually applied to the ejection energy generating element of the print head when printing is performed under an arbitrary temperature condition (T,) deviating from the reference temperature.
can be determined from 20 using the value of vT at the reference temperature.

However, when temperature compensation is performed based on such a principle, the relationship expressed by the equation (2) expressed as a -order number is incorrectly expressed between the drive voltage (V) and the ejected droplet volume (Z). It must be established.

However, depending on the recording liquid used, the relationship shown in equation (2) may not hold, and good temperature compensation cannot be achieved.After various studies, the inventors of the present invention found that the reason for this depended on the temperature conditions. They discovered that it depends on the viscosity of the recording liquid.

That is, as will be shown later in the Honorary Examples, for recording liquids whose viscosity is always within the range of 3 to 30 cp, good droplet ejection conditions can be obtained as shown in Table 1, and as shown in FIG. As shown in , the relationship between ■ and 2 is always expressed as a linear function shown by the above equation (■). Therefore, if these recording liquids are used, good temperature compensation is always possible. Also,
If a material outside this range is used, good droplet ejection conditions may not be obtained or ejection may become impossible, and a good temperature compensation function will not be exhibited.

The viscosity of the recording liquid used in the method of the present invention is adjusted so that it is always within the range of 3 to 30 cp under temperature-compensated temperature conditions. An inkjet recording device fl! having such a temperature compensation means can function effectively. (
The one you use is particularly suitable.

The recording liquid used in the present invention is basically composed of a dye or pigment as a recording agent component, and a solvent containing water or wood and a water-soluble solvent.

As the recording agent component used in this recording liquid, dyes that are generally used in recording liquids for inkjet recording can be used.

The concentration of the dye as a recording agent component in the recording liquid used in the method of the present invention is usually appropriately selected from the range of 0.1 to 4.0% by weight.

The viscosity of the recording liquid used in the method of the present invention and its temperature characteristics (
As described above, the viscosity at the temperature at which temperature compensation is performed is adjusted by the temperature compensating means so that it is always within the range of 3 to 30 cρ.

The viscosity and temperature characteristics of the recording liquid according to the present invention can be determined by appropriately selecting the composition of the water-soluble solvent mainly contained, or by using a viscosity modifier such as polyvinyl alcohol, cellulose, or water-soluble resin. ! The above can be adjusted within the above range by adding an appropriate Jl to the recording liquid. Note that these methods may be used in combination.

This water-soluble solvent, which can adjust the viscosity of the recording liquid by changing its composition, is a component of the dye solvent and also acts as a wetting agent to prevent clogging of the droplet ejection opening (orifice). . Examples of such water-soluble solvents include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol,
n-butyl alcohol, 5eC-butyl alcohol,
Alkyl alcohols with 1 to 4 carbon atoms such as tert-butyl alcohol and isobutyl alcohol; Amides such as dimethylformamide and dimethylacetamide; Ketones or ketone alcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane. Nitrogen-containing heterocyclic ketone neck such as N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone:
Polyalkyl glycols such as polyethylene glycol polybrobylene glycol: ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1.2.6-hebosantriol, thiodiglycol, hexylene glycol, diethylene glycol
Alkylene glycols in which the alkylene group has 2 to 6 carbon atoms, such as kohl: Glycerin: Polyhydric alcohols such as ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether, etc. Examples include lower alkyl ethers.

The content of the above-mentioned water-soluble solvent in the recording liquid used in the method of the present invention is generally 5 to 5% by weight based on the total amount of the recording liquid.
95%, preferably within the range of 10 to 80%, and within this range, the recording liquid has the above-mentioned characteristics:
What is necessary is just to select suitably the content which has.

In addition, those which can be effectively used as the above-mentioned water-soluble solvent and the above-mentioned viscosity modifier include 2-dololidones, polyalkylene glycols, monoethers of polyalkylene glycol, polyoxyethylene alkylphenyl ethers, etc. can be mentioned.

Recording liquids consisting of the basic components mentioned above already have recording properties (signal response, droplet formation stability, ejection stability, long-term continuous recording performance, ejection stability after long-term recording pauses).
The storage stability, dissolution stability of the recording agent, fixation to the recording material, and the light resistance, weather resistance, water resistance, and alcohol resistance of the recorded image are all well-balanced and excellent. The viscosity is adjusted so that the viscosity at the temperature at which temperature compensation is performed by the temperature compensation means is always within the range of 3 to 30 cp, and if this recording liquid is used when performing inkjet recording, the driving voltage and ejection liquid The relationship expressed by equation (2), which is a linear function explained earlier, is always satisfied between the droplet volume and the temperature compensation means, so that the temperature compensating means can perform its function well.

The recording liquid 1 used in the method of the present invention may contain various additives such as a surfactant, a pH adjuster, a resistivity adjuster, etc. in order to further improve its recording properties, storage stability, fixing properties to recording members, etc. Agents may be added and contained as necessary.

〔Example〕

The present invention will be explained in more detail below using reference examples and examples.

As an example dye, C,1, Direct Ye 0-86 was used,
After preparing each component as shown below, stir and mix until the dye is almost completely dissolved, and then filter under pressure using a Pro 0 Bore Filter (Sumitomo Electric) with a pore size of 1.0- The filtrate was obtained as Recording Liquid A.

Recording liquid A (composition) C,! , Direct Yellow 86 0.7 parts by weight Diethylene glycol 10 N-methyl-2-pyrrolidone 18 Acetinol EHO, 18n Water 60 Further, in the same manner, recording liquid 8 was prepared so as to have each composition shown below.
, C, O and E were adjusted.

Recording liquid date (composition) c, r, direct yellow 86 0.7 weight J1g
B Diethylene glycol 22 N-methyl-2-gorolidone 18 Acetinol EH0118// Water 60 Recording liquid C
(Composition) c, r, Direct Ye 0-86 0.7 parts by weight diethylene glycol 37 Polyethylene glycol (#300) N ttN-methyl-2
-pyrrolidone +2 uacetinol EHO
,18ti water 40
Recording liquid D (composition) c, r, Direct Yellow 86 0.7 parts by weight polyethylene glycol (#300) 73 II water
27 Recording liquid E (composition) C, 1, Direct Yellow 86 0.7 parts by weight polyethylene glycol (well 300)'? a water
22. The viscosity and surface tension at 25°C of each of the recording liquids thus adjusted (
a is shown in Table 1.

Table 1 Next, a cylindrical nozzle type on-demand inkjet recording head with an orifice diameter of 50 mm and equipped with a cylindrical piezoelectric element as an energy generating element was used to drive the recording liquids A to H separately. A recording liquid ejection test was carried out under a temperature condition of 25° C. by continuously changing the voltage from 30 to 80 V, and the ejected droplet volume at each drive voltage was measured.

FIG. 1 shows the relationship between the drive voltage and the ejected droplet volume when recording liquids B, C, and D were used. When these recording liquids were used, good droplet ejection conditions were obtained (Table 1).
, and as shown in FIG. 1, the relationship between the drive voltage and the ejected droplet volume satisfied the linear function relationship expressed by the above equation (2).

On the other hand, when recording liquid A is used, a normal ejection state from the orifice cannot be obtained, and the relationship between the drive voltage and the ejected droplet volume does not satisfy the linear function relationship expressed by the above formula (■). There wasn't. Furthermore, when recording liquid E was used, the recording liquid could not be ejected, and recording itself could not be performed.

Example 1 A recording liquid was prepared in the same manner as in the above reference example except that the following components were used.

Recording liquid composition C, 1, Food black 2 2 Parts by weight N-methyl-2-pyrrolidone 12 Ethylene glycol 25 Diethylene glycol
23〃Acetinol EHO,0211 Thu 40//
This recording liquid had a viscosity of 5.5 cp and a surface tension of 50 dyne/cn+ at 25°C.

The viscosity of this recording liquid was measured under temperature conditions that gradually changed from 5°C to 40°C, and the viscosity was 3.5 to 13. It changed to OCρ.

Furthermore, a recording device using this recording liquid, equipped with a temperature compensation system configured as shown in the block diagram of FIG. Using M, the same image was recorded at each predetermined temperature while the temperature inside the recording head was gradually increased from 5° C. to 40° C.

The configuration and operation method of the temperature compensation system shown in FIG. 2 are as follows.

1-1 is a discharge signal control means, and a converter 1-1-a
and an arithmetic unit 1-1-1). Reference numeral 1-2 denotes an inkjet recording means, and the volume of ejected recording liquid droplets is controlled by drive voltage data based on the output 1-8 from the control means 1-1. 1-3 is a temperature detection means;
-2 temperature is detected by a sensor, converted into an electrical signal, and outputted to the calculation section as a temperature signal 1-C.

The data l-A regarding the driving voltage corresponding to the ejected droplet volume of the recording liquid necessary for printing is converted by the converting section 1-1-a l into an output voltage signal necessary for ejecting at a reference temperature, and the data is sent to the calculating section 1. -1-b. On the other hand, temperature detection means 1-
3 detects the temperature inside the recording means 1-2 and uses this data as an electric signal 1-C to calculate f! ! 8l-1-b Input this. The two types of signals inputted to the calculation unit 1-1-b in this way are processed by the calculations explained earlier in the text using formulas 1 to 2, and an output voltage signal corresponding to the temperature in the recording means 1-2 is output. It is input to the recording means 1-2 as 1-8.

In this way, temperature compensation processing is performed in accordance with the temperature within the recording means, and the data I-
Printing is performed by ejecting recording droplets having a predetermined volume that exactly corresponds to A.

In recording with such an apparatus using the recording liquid obtained in this example, the temperature compensation system as described above always works well within the temperature range of 5°C to 40°C.
At any temperature within these temperature ranges, excellent image quality could be recorded with good reproducibility, for example, without any difference in image density between images recorded at each temperature.

In addition, using the same device and temperature conditions in the recording head as above, the voltage of the ejection signal applied to the recording head is changed to control the size of the droplet to be ejected, thereby recording while changing the dot diameter. However, when we recorded a high-quality image that expressed halftones in gradation consisting of subtle changes in shading, we were able to reproduce and reproduce high-quality images at any temperature within the above temperature range. I was able to get a good deal.

Example 2 A recording liquid was prepared in the same manner as in Example 1, except that the composition of the recording liquid was changed as follows, and then inkjet recording was performed.

Recording liquid (composition) C, 1, Food black 2 2 Parts by weight N-methyl-2-biolidone 12 Ethylene glycol 37 Polyethylene glycol (well 300) II // Acetinol EHO, 01 II Water 40 This record The viscosity of the liquid at 25° C. was 7.5 cp, and the surface tension was 51 dyne/cm.

The viscosity of this recording liquid under a temperature condition of 5° C. to 40° C. was 4.4 to 17.4 cp.

Even when using the recording liquid obtained in this example, the temperature compensation system always works well within the temperature range of 5°C to 40°C, and excellent image quality is achieved at any temperature within these temperature ranges. It was possible to record with good reproducibility.

Furthermore, when high-quality images were recorded, high-quality images could be obtained with good reproducibility at any temperature within the above temperature range.

Comparative Example A recording liquid was prepared in the same manner as in Example 1, except that the composition of the recording liquid was changed as follows, and then inkjet recording was performed.

Recording liquid (composition) C, 1, Food black 2 2 Parts by weight Tomethyl-2-dorolidone Ig // Diethylene glycol 22 Acetinol εHO, 03
//Wed 60
〃The viscosity of this recording liquid at 25°C is 3. Ocp
, the surface tension was 50 dyne/cm.

Further, the viscosity of this recording liquid under a temperature condition of 5°C to 40°C is 1.7 to ? , tcp.

When the recording liquid obtained in this comparative example was used, the viscosity of the recording liquid was 1.7 to 3.5°C when the inside of the recording head was under a temperature condition of 25 to 40°C. Ocp, the driving voltage and ejected droplet volume explained earlier deviate from the range necessary to satisfy the linear function relationship of the above equation (2), and a good temperature compensation function is not exhibited in this temperature range. At each temperature within this temperature range, there were differences in image density, and depending on the temperature conditions, images of good quality could not be obtained.

[Effects of the Invention] According to the method of the present invention described above, in an inkjet recording method that performs temperature compensation by adjusting the voltage of the ejection signal, temperature compensation of the ejected droplet volume of the recording liquid can always function well. becomes possible.

Therefore, the present invention makes it possible to apply a temperature compensation system based on a method of adjusting the voltage of an ejection signal to an inkjet recording method for recording high-quality images, thereby reducing power consumption, cost, and size. It has become possible to print high-quality images with good reproducibility, unaffected by temperature environments, using a modern inkjet printing apparatus.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the drive voltage and the ejected droplet volume when recording liquids B, C, and D prepared in Reference Example 1 are used individually, and FIG. 7099 showing the configuration of the temperature compensation system of
It is a diagram. 1-1 Control means 1-1-a Conversion section 1-1-b Arithmetic section 1-2 Inkjet recording means 1-3 Temperature detection means 1-A Data +-8 output voltage signal 1-C temperature signal

Claims (1)

[Claims] 1) The temperature within the droplet forming means for forming ejected droplets of the recording liquid is detected by the temperature detecting means according to the applied electric signal, and the temperature within the droplet forming means is detected according to the output from the temperature detecting means. By adjusting the electric signal to be applied by the ejection signal adjustment means, the volume of the ejected droplet is temperature-compensated and recorded, and within the temperature range within the droplet forming means that is temperature-compensated during recording. , 3~30c
An inkjet recording method characterized by using a recording liquid having a viscosity of p.